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CPD NR 3264 Conceptual Process Design

Process Systems Engineering

DelftChemTech - Faculty of Applied Sciences Delft University of Technology

Subject

Production of Chitin and Chitosan from Shrimp Shells

Authors Telephone A.A.Khan (Atif) H.Shibata (Hiro) M.T.A.P.Kresnowati (Penia) S.L.Tai (Tai)

06-12058509 06-14662045 06-14380408 06-15447975

Keywords Shrimp shell, chitin, chitosan,lactic acid fermentation, Enzymatic deprotenization, demineralization, Chemical deacetylation

Assignment issued : 01-10-01 Report issued : 21-12-01 Appraisal :

St-4931 Conceptual Process Design Production of Chitin and Chitosan from Shrimp Shells

CPD 3264 -i-

Summary The purpose of this report is to introduce with detailed guidance the possibility of extracting chitin and chitosan from shrimp shells via enzymatic routes. Discovered in 1811 by Professor Henri Braconnot, chitin has gain an outstanding reputation in the recent decades as a renewable natural product. Chitin is deacetylated into derivates like chitosan and these compounds are generally non-toxic, non-soluble in water and most organic solvents. Currently, there are less than fifteen (15) major processors of chitin and chitosan worldwide. Of these major processors, only one is located in the United States, two are in Canada, two in Scandinavia, and the balance in Asia. There are numerous small processors throughout Asia. Many of these small processors are located in small remote villages, making transportation of the end product rather difficult and production quantity and quality unreliable. A medium sized chitosan plant produces about 500 tonnes per year. Hence, only about 5 % of shrimp shells produced worldwide are considered for chitin/chitosan production. World production of shrimp shells is 1.7 million tones per year, and chitosan 85,000 tonnes per year. This plant is built in Morrocco and has the capacity of 780 tonnes per year, a medium sized plant. The plant is run 335 days continuously in a year, taking 10 % of the year for plant over haul. Here it covers maintenance, start-up and shut down processes as well as when emergency arises. Chitosan produced in this plant is of medical grade, which will be able to fetch € 453 per kilogram; a large return for a raw material (shrimp shells) which is waste of shrimp industry. The plant design via enzymatic routes is novel and currently there are no plants running in the world using this technology. Current plants work chemically with highly concentrated HCl and NaOH, which is an environment threat. The basis of the plant design was done from experimental data done in lab scale and transferred into a theoretical large scaled process. Lactic acid produced by lactic acid bacteria in a fermentor is used to demineralize and deprotenize the shrimp shells and later using mild HCl, purified chitin is produced. Chitosan is produced by means of NaOH, but not enzymatic routes as research for chitosan production via enzymatic routes is still in developing stages. It is known that for the chitin production via in-situ lactic acid fermentation process, there is a pilot scaled plant already running in the Asian Institute of Technology in Thailand. The total investment costs is € 9.512 million. Plant construction takes 2 years and the lifetime of the plant is 15 years. Cash flow from this project is estimated at € 340 million, with the Pay-Out-Time of 10 days. In terms of sensitivity, a fluctuation in product or raw material prices of +/-10 % will give little effect on the Pay-Out-Time. Even if the production costs multiplies to double it doesn’t make much effect on the economics. So the process is insensitive to variations. In conclusion, this process is mainly very profitable and feasible. Chitosan has a bright future as a biopolymer in many industries. This industry has much potential to grow as chitosan has gain much attention in recent years in the medical and wastewater industry. It is suggested that more research and pilot plants studies should be done to get the complete reaction kinetics and missing properties before introducing enzymatic process to produce chitosan. It may be a suggested that when designing an enzymatic plant, the use of concentrated NaOH or HCl separately should be avoided as waste produced would be too alkaline or acidic. The plant should be designed fully enzymatic or fully chemical.


CPD 3264 ii

Table of ContentsChapter and Title

Summary 1 Introduction 2 Process, Options and Selection

2.1 Process Concept Chosen 2-12.2 Creative Decision Making Process 2-4

3 Basic of Design 3-13.1 Description of the Design 3-13.2 Process Definition 3-1

3.2.1 Process Concept Chosen 3-13.2.1.1 Reaction Stoichiometry 3-23.2.1.2 Kinetics 3-2

3.2.2 Block Schemes of Chitosan Production 3-53.2.3 Thermodynamic and Pure Component Properties 3-6

3.3 Basic Assumptions 3-93.3.1 Plant Capacity and Location 3-93.3.2 Battery Limit 3-9

3.3.2.1 Main Units Description 3-93.3.2.2 Facilities 3-103.3.2.3 Shrimp Shell Properties and Product Specification 3-11

3.3.3 Input Output Streams and Diagram 3-123.4 Economic Evaluation 3-14

4 Thermodynamics 4-14.1 Thermodynamics General Concept 4-14.2 Thermodynamics Model 4-14.3 Validation of Property Method 4-2

4.3.1 Properties Comparison 4-24.3.2 Operating Windows 4-3

4.4 VLE and Solubility 4-34.4.1 Ethanol - water VLE 4-34.4.2 Benzoic Acid-Ethanol-Water Solubility 4-4

4.5 Heat of Reaction 4-44.5.1 Demineralization, Deacetylation, and Neutralization 4-44.5.2 Deproteinization 4-4

5 Process Structure and Description 5-15.1 Criteria and Selections 5-1

5.1.1 Lactic Acid Fermentation 5-15.1.2 Shrimp Shell Pretreatment 5-1

5.1.2.1 Shrimp Shell Size Reduction 5-15.1.2.2 Impurity Separator 5-2


CPD 3264 iii

Table of Contents (cont'd)Chapter and Title

5.1.3 Enzymatic Deproteinization and Demineralization + Chitin Purification 5-35.1.3.1 Reactors 5-45.1.3.2 Filtration 5-45.1.3.3 Mixing Tank 5-5

5.1.4 Chitin Deacetylation 5-55.1.4.1 Mixing Tank 5-55.1.4.2 Deacetylation Reactor 5-55.1.4.3 Filtration 5-55.1.4.4 Drying 5-55.1.4.5 Grinder 5-6

5.1.5 Pump Selection 5-65.2 Process Flow Scheme (PFS) 5-65.3 Utilities 5-85.4 Process Yields 5-9

6 Process Control 6-16.1 Section 1: Lactic Acid Fermentation 6-1

6.1.1 R101 a/b Lactic Acid Fermentor 6-16.1.2 S101 a/b Microfilter 6-26.1.3 T101 Lactic Acid Buffer Tank 6-2

6.2 Section 2: Shrimp Shell Pretreatment 6-26.2.1 C201 Ethanol evaporator 6-26.2.2 T201 Ethanol Buffer Tank 6-26.2.3 S201 Benzoic Acid Extractor 6-3

6.3 Section 3: Enzymatic Deprotenization and Demineralization + Chitin Purification 6-36.3.1 R301 a/b Enzymatic Deprotenization and Demineralization Reactors 6-36.3.2 S301 and S302 Vacuum Drum Filters 6-36.3.3 R302 Chitin Purification Reactor 6-3

6.4 Section 4: Chitin Deacetylation 6-46.4.1 R401 Deacetylation reactor 6-46.4.2 S401 Vacuum Drum Filter 6-46.4.3 D401 Product Dryer 6-4

7 Mass and Heat Balances 7-17.1 Practical Aspects 7-17.2 Balance for Total Streams 7-17.3 Balance for Stream Components 7-1


CPD 3264 iv

Table of Contents (cont'd)Chapter and Title

8 Process and Equipment Design 8-18.1 Integration by Process Simulation 8-1

8.1.1 Component settings 8-18.1.2 Thermodynamics Model 8-38.1.3 Reactions 8-38.1.4 Feed 8-48.1.5 Setting of Units 8-4

8.2 Equipment Selection and Design 8-88.2.1 R101 a/b Lactic acid Fermentor and S101 a/b Microfilters 8-88.2.2 R301 a/b, R302 and R401 Reactors 8-10

8.2.2.1 Reactor Configuration 8-108.2.2.2 R301 a/b Chitin Demineralization and Deproteinization 8-138.2.2.3 R302 Chitin Purification with HCl 8-158.2.2.4 Chitin Deacetylation and Deprotenization with NaOH 8-158.2.2.5 Material of Construction 8-16

8.2.3 S301, S302 and S401 Vacuum Rotary Drum Filters 8-178.2.3.1 Design of the filters 8-18

8.2.4 A201 Shrimp Shell Crusher and A401 Chitosan Grinder 8-198.2.4.1 A201 Shrimp Shell Crusher 8-198.2.4.2 A401 Chitosan Grinder 8-21

8.2.5 Heat Exchangers and Evaporators 8-228.2.5.1 C201 Ethanol Evaporator 8-228.2.5.2 Heat Integration and Heat Exchanger 8-24

8.2.6 Vessels 8-278.2.6.1 S201 Benzoic Acid Extractor 8-278.2.6.2 D401 Product Dryer 8-298.2.6.3 T101 & T201 Buffer Tanks 8-328.2.6.4 V301 & V401 Mixing Tanks 8-32

8.2.7 Pipes and Pumps 8-328.2.7.1 Pressure Drop, Line Size and Pumps 8-33

8.3 Equipment Data Sheets 8-349 Waste

9.1 Introduction and Definition of Waste 9-19.2 Identifying and Classifying Waste 9-2

10 Process Safety 10-110.1 Hazop 10-1

10.1.1 R401 Deacetylation 10-110.1.2 C201 Ethanol Evaporator 10-3

10.2 Dow Fire and Explosion Index (FEI) 10-511 Economy 11-112 Conclusions and Recommendations 12-1

List of Symbols Reference


CPD 3264 v

Appendices Table of ContentNumber Title

A Base of Design A-1 A.1 Basic Assumptions A-2 A.2 Kinetics A-3

A.2.a Demineralization (Lactic acid) A-3A.2.b Enzymatic Deproteinization A-5A.2.c Chemical Demineralization (Hydrochloric acid) A-6A.2.d Chemical Deproteinization A-7A.2.e Chemical Deacetylation A-8

A.3 Shrimp Shell Compositions A-9B Thermodynamics B-1C Process Structure, Description, and Balances C-1

C.1 Process Flow Scheme Diagram C-2C.2 Utilities Summary C-7C.3 Process Stream Summary C-10

D Equipment Design D-1D.1 Integration by Process Simulation D-2D.2 Lactic Acid Fermentation (R101 a/b) D-11

D.2.a Stoichiometry D-12D.2.b Mass Balance of Fermentation D-13D.2.c Reaction Condition Optimization D-14D.2.d Fermentation Simulation D-15D.2.e Dimensioning of Fermentor D-18D.2.f Cooling Requirement D-19D.2.g Microfilter Design D-19D.2.h Superpro Designer Simulation D-19

D.3 Reactor Simulation (R301 a/b, R302, R401) D-22D.3.a Mean Conversion and Total Reactor volume for CSTRs in N series D-23D.3.b Residence Time Distribution D-23D.3.c Impeller D-25

D.4 Rotary Drum Filter (S301, S302, S401) D-27D.4.a Sample Calculation (S301) D-28D.4.b Comparison to Aspen Plus Simulation D-32

D.5 Shrimp Shell Crusher (A201) and Chitosan Grinder (A401) D-33D.5.a A201 Shrimp Shell Crusher Design D-34

D.5.a.a Energy Utilization for Size Reduction D-34D.5.a.b Equipment Design D-34

D.5.b A401 Chitosan Grinder D-37D.5.b.a Vessel Design D-38

D.6 Evaporators and Heat Exchangers D-39D.6.a C201 Ethanol Evaporator D-40

D.6.a.a Design of the Vessel D-40


CPD 3264 vi

Appendices Table of Content (cont'd)Number Title

D.6.b Heat Integration and Heat Exchanger D-48D.6.b.a Design Heat Exchanger for Sterilization D-48D.6.b.b Design Heat Exchanger for Ethanol Evaporation System D-50

D.7 Extractor, Dryer, Buffer and Mixing Tanks D-57D.7.a Benzoic Acid Extractor (S201) D-58

D.7.a.a Number of Stages D-58D.7.a.b Equipment Design D-60

D.7.a.b.a Mass Transfer in Leaching Operations D-60D.7.b Product Dryer D-64D.7.c Buffer Tanks (T101 and T102) D-66D.7.d Mixing Tanks (V301 and V401) D-67

D.8 Pump and Line Calculation D-69D.9 Equipment Data Summary Sheets and Specification Sheets D-81

E Waste Streams E-1F Economics F-1


CPD 3264 vii

Symbols Symbol Description Units Symbol Description Units

A area m2 N number of CSTRs -A amount of HCl N·l/kg P power requirement W

Across cross sectional area of tube m2 P protein fraction kg/kg

Atube tube area m2 qp product specific rate h-1

b effective thickness m qs substrate specific rate h-1

B amount of NaOH N·l/kg Q heat kJ/sc concentration of solute kmol/s Qin Vol. flowrate in m3/h-1

CAO feed concentration kmol/m3 Qp Flow rate pump m3/day

Cp product concentration kg/m3 r specific resistance m-2

CP Specific heat capacity kJ/kg C rA reaction rate kmol/sCS substrate concentration kg/m3 S specific surface of

particlesm-1

Cx biomass concentration kg/m3 t time sd pipe diameter m t temperature Cdi inner tube diameter m tA time for specification sdo outer tube diameter m tB time for 10 % less sdoptimum optimum pipe diameter m mean residence time sD dilution factor h-1 T temperature KD diameter m u velocity m/sDc Column diameter m Uo overall heat transfer

coefficientW/m2 K

Ds shell diameter m ut velocity in tubes m/se voidage - V volume m3

E energy consumption kWh/ton Vw vapour flow rate in evaporator

kg/s

E activation energy kJ/kmol x mass fraction -E(t) Residence time distribution - x1 feed particle size mmEi Bond work index kWh/ton x2 product particle size mmf friction factor - xAf conversion of outlet -F correction factor - xAO conversion of feed -F vol. flow rate m3/minF(t) cumulative residence time -g mass flow rate kg/s Greek Description SI UnitG gravitational acceleration m/s2

h heat transfer coefficient W/m2 K degree of polynomial -hev enthalpy of evaporation kJ/kg degree of polynomial -H height m % biomass not recycled -Hcond enthalpy of condensation kJ/kg Gcat Gibbs free energy for

catabolic reactionkJ/mol

Hevap enthalpy of evaporation kJ/kg GGibbs Gibbs free energy kJ/molk reaction constant s-1 Greact Gibbs free energy for

reactionkJ/mol

k’ diffusion coefficient m2/s -P pressure drop kPa/mK reaction equilibrium constant - tm mean logaritmic CKS specific affinity coefficient on

substrate Cmol/m3 T temperature difference C or K

l vapour space m TLMTD mean logaritmic temperature difference

K

L length m L vol. liquid flow rate m3/hL lactic acid concentration kg/m3 heat transfer efficiency -m mass flow rate kg/s viscosity Ns/m2

mGibbs maintenance coefficient on Gibbs free energy

kJ/C-mol h-1 max maximum growth rate

ms maintenance coefficient on substrate

h-1 L liquid density kg/m3

M mass flow rate kg/h v vapour density kg/m3

M mineral fraction kg/kg residence time min

it


CPD 3264 viii

References: Chapter 1 [1] http://www.st.nmfs.gov/st1/fus/fus98/world/w-specie.pdf [2] www.ill.cri.nz , March 2001 [3] www.sigma-aldrich.com [4] L. Henry Larry, Biomaterial, A forecast for the future, Biomaterials 19, 1998 [5] Hall, G.M. Silva,S.D. Biotechnology 1994, pp.633 - 638 [6]Baustita, J. Jover, M., Process Biochemistry, 37, 2001, pp. 229 - 234 [7] Tsigous , I. Martinou, A., Trends in Biotechnology, Vol. 18, 2000, pp.305 – 312 [8] No, H.K. Cho, Y.I., Journal of Agricultural and Food Chemistry, Vol. 48, No. 6, 2000, pp.2625–2627 Chapter 2 [1] Seidell,A. Solubilities of Organic Compounds, 3rd ed. Vol. II, 1941, pp.510 [2] Roberts, G.A.F., Chitin Chemistry, MacMillan, 1992 [3] Wang, S.L., Chio, S.H. Enzyme and Microbial Technology, 22, 1998, p.629 – 633 [4] Gilberg, A. Stenberg, E. Process Biochemistry, 36, 2001, p.809 – 812 [5] Legarreta, I.G. Zakaria, Z., Hall, G.M., Lactic Acid Fermentation of Prawn Waste; Comparison of

Commercial and Isolated Starter Culture, EUCHIS I, Drest, 1995 [6] Baustita, J. Jover, M., Process Biochemistry, 37, 2001, pp. 229 - 234 [7] Zakaria, Z. Hall, G.M., Shama, G. Process Biochemistry, 33, 1998, pp.1 – 6 [8] Shirai, K. Legaretta, I.G., Serrano, G.R. Aspect of Protein Breakdown during the lactic acid fermentation of

prawn waste, EUCLIS 2, 7th ICCC, Lyon, 1997 [9 ] www.astaxanthin.org, April 2001 [10] Tsigous , I. Martinou, A., Trends in Biotechnology, Vol. 18, 2000, pp.305 – 312 [11] Kolodziejska, I. Woojtasz-Pajak, A., Ogonowska, G., Sikorski, Z.E., Bulettin of The Sea Fisheries Institute,

2(150), 2000, pp.15-23 [12]Kolodziejska, I. Malesa-Ciecwierz, M., Lerska,A., Sikorski, Z.E, Journal of Food Biochemistry, 23, 1999,

pp.45-47 [13] No, H.K. Cho, Y.I., Journal of Agricultural and Food Chemistry, Vol. 48, No. 6, 2000, pp.2625–2627 [14] Cho,Y.I., No,H.K., Journal of Chitin and Chitosan, 4(3), 1999, pp.152-155 Chapter 3 [1] J.Bautista, M.Jover, Process Biochemistry, 37, 2001, pp229-234 [2] No,H.K., Hur,E.Y., Journal of Agricultural and Food Chemistry, 46(9), 1998, pp. 3844-3846

[3] Chang,k.L. Tsai,G., Journal of Agriculutral and Food Chemistry, 45, 1997, pp.1900-1904

[4] I Kolodziejska, A Wojtasz-Pajak, Bulletin of The Sea Fisheries Institute, 2 (150), 2000, 15-24 [5] Yaurs,C.L. Chemical Properties Handbook, McGraw Hill, 1999

[6] Lide,D.R. CRC Handbook of Chemistry & Physics, 81st ed. 2000-2001

[7] Chemiekaarten

[8] Sax’s Dangerous Properties of Industrial Materials

[9]No, H.K.,Hur, E.Y., Journal of Agricultural and Food Chemistry, 48, 2000, p. 2625 - 2627 [10] www.chitin.org, 2001

Chapter 4 [1] http://sty.cc.yamaguchi-u.ac.jp/~speleo/Solution-Caves.html [2] http://www.encyclopedia.com/printablenew/04238.html [3] Solubilities of Organic Compounds, Atherton Seidell, 3rd Vol2 1941 [4] http://wwwbmcd.nist.gov:8080/enzyme/ename.html


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Chapter 5 [1] www.membranegroup.kt.dtu.dk [2] Table 10.13 in Coulson & Richardson Vol 6 3rd Edition, p 464 [3] Robert H. Perry, “Perry’s Chemical Engineers’ Handbook, 7th Edition”, p 18-105, Table 18-11 [4] Coulson and Richardson, “Chemical Engineering Vol 6”, 2nd Edition [5] A.S. Mujumdar & Menon, “Handbook of Industrial Drying” 2nd Edition, Vol 1, 1995 [6] C.M. van’t Land, “Industrial Drying Equipment, Selection & Application” Marcel Dekker 1991 [7] www.americanlewa.com [8] www.edsonpumps.com Chapter 6 - Chapter 7 - Chapter 8 [1] http://www.chemicalogic.com/co2tab/product_information.htm [2] C. Akerberg, et.al. Applied Microbiology and Biotechnology. 1998. 49 : 682 – 690 [3] Conceptual Design of Chemical Processes , J.M. Douglas [4] Ke Liand B Cheng, Response Surface Optimization and Kinetics of Isolating Chitin from Pink Shrimp Shell

waste, Taiwan [5] Sinnott “Coulson & Richardson Vol 6”, 2nd Edition p 478 [6] Robert H. Perry, “Perry’s Chemical Engineers’ Handbook, 7th Edition”, Chapter 20 [7] Coulson and Richardson, “Chemical Engineering Vol 6”, 2nd Edition, p 499 [8] Robinson, R.K. Encyclopedia of Food Microbiology vol.2 2000 p.681 [9] Bennett & Myers, Momentum, heat and Mass Transfer p 501 [10] Sinnott, R.K, Coulson & Richardson Chemical Engineering, Vol 6., 3rd Edition, Butterworth-

Heinemann,1999 [11]Warring, R.H, Pump: Selection, system and Application, 2nd Edition, Gulf publishing Co, 1984 [12] Perry, R.H, Perry’s Chemical Engineer’s Handbook, 7th Edtion, McGraw-Hill Int’l ,1998 Chapter 9 [1] R.Bahu, B. Crittenden, J. O’Hara, Management of Process Industry Waste,1997 [2] H.J. Pasman, S.M. Lemkowitz, Chemical Risk Management, TU Delft 2001 Chapter 10 - Chapter 11 [1] Sinnott, R.K, Coulson & Richardson Chemical Engineerig, Vol 6., 3rd Edition, Butterworth-

Heinemann,1999 [2] Timmerhaus, K.D, Plant Design and Economics for Chemical Engineers, 4th Edition, McGraw-Hill Intl,

1991 [3] www.process-heating.com [4] www.brewtechinc.com [5] Perry, R.H, Perry’s Chemical Engineer’s Handbook, 7th Edtion, McGraw-Hill Int’l ,1998


CPD 3264 1-1

Chapter 1. Introduction

This assignment on Conceptual Process Design concerns the production of chitin and chitosan from the exo-skeleton of crustaceans (shrimp shells). 20.8 % of the shrimp shells consist of chitin, while the rest are of protein, minerals and carbohydrates. Table 3.3.3 shows the composition of shrimp shells. Currently, most shrimp shells are discarded as waste, and only a small percentage are used to produce chitosan. The world market of shrimp shells is 1.7 million tones/yr, and only about 5 % is used for chitin and chitosan production[1]. This makes the world market of chitosan to be about 85,000 tonnes/year. Chitosan is much preferred as the end product to chitin because chitin has poor solubility and this is a major limiting factor in its utilization. Furthermore the price of chitosan is approximately 1.5 times the price of chitin[2]. The market price of Chitosan is estimated at €453 per kg[3]. Overall the process produces 780 tones of Chitosan, which sells at € 453 per kg. Chitosan will be sold in packages of 10 or 25 kilograms to mainly biomedical, cosmetic and biotechnology customers. The cash flow is € 340 million per year, and the Pay-Out-Time amazingly just in 10 days. The huge margin of € 340 million is due to the fact that the main raw material is a waste of shrimp industry and is available free of cost.

Chitosan is derived from chitin by deacetylation. Chitin is one of the most attractive biopolymer because of its unique physiochemical and biological properties, such as the ability to form films, polyoxysalt formation, chelation of metal ions and optical structural characteristics [4]. It is one of the most abundant, easily obtained and renewable polysaccharide, second only to cellulose. Utilization of chitin and chitosan is very promising in various fields including medicine, pharmacology and the food industry as a result of their biological activity, biocompatibility and biodegradability in combination with low toxicity.

Currently, chitin and chitosan are used in wastewater treatment for removal of metal ions and flocculants (i.e. protein, dye and amino acids), food industry as a preservative, colour stabilization and animal feed additive. Chitosan is used largely in the biomedical field for bandages, blood cholesterol control, controlled released of drugs, skin burns and the development of contact lenses. The cosmetic industry has benefited from chitin and chitosan because of its hydrating power, while in biotechnology and membrane development, chitosan shows promising properties in enzyme and cell immobilization, protein separation, cell recovery, and chromatography. Future developments have also been investigated in the fields of mainly biomedical. To name a few, chitin and chitosan are suggested for application in treatment of tumours (Leukemia) and aiding bone formation.

Chitosan quality is mainly defined by its solubility; Chitosan is higher in quality when solubility in weak acids increases. This can be attained by using mild conditions during deacetylation or by using technology that requires low contact time.

In the recovery of chitin from shrimp shells, the removal of proteins and associated minerals normally requires the use of hydrochloric acid (HCl) and sodium hydroxide (NaOH). These methods involve alternate hydrochloric acid and alkali treatment stages to remove calcium carbonate and protein respectively, followed by a bleaching stage with chemical reagents to obtain a colorless product. An alternative to these harsh chemical treatments is the use of weak acids and proteolytic enzymes present in the shrimp shells. It has been reported that the reaction of crustacean shells with lactic acid bacteria lowered the pH of the medium to approximately 5.5, facilitating the hydrolysis of proteins and minerals while leaving the associated chitin intact [5]. A bleaching process is not required for this enzymatic process because of the mild conditions.


CPD 3264 1-2

The main reason for choosing lactic acid fermentation is so that the recovery of the protein and mineral fraction is possible, and also that the chitin produced is of good quality. The chosen species for lactic acid bacteria is lactobacillus sp. B2, which is a homo-fermentative bacterium, i.e. it only produces lactic acid as a product. Hetero-fermentative bacteria on the other hand like lactobacillus pentosus produce side products like ethanol, acetate and CO2, therefore reducing the yield of lactic acid. Proteolytic enzymes are obtained from the existing enzymes present in the shrimp shells which are released during lactic acid treatment.

Chitosan is produced through deacetylation of chitin. Chitin from shrimp shells is naturally partially deacetylated at about 20-30 %[6]. Generally this step occurs under severe conditions using caustic soda at high concentrations and high temperature, which will degrade the quality of chitosan produced. An alternative to this step is also the use of enzymes but the technology available is still in the developing stages and also a preliminary chemical treatment is compulsory for all such process [7]. The treatment chosen for effective deacetylation with the production of high grade chitosan is by using high concentrations of NaOH at autoclaving conditions (15 psig, 121 C). By this method chitin is about 90% deacetylation and chitosan is not degraded in the process[8]. The choice of process used is discussed in Chapter 2.

The objective of the project is to make a conceptual process design for the production of chitosan from shrimp shells. The design will be based on enzymatic production of chitin. Chitosan will be produced chemically from chitin with an effort to utilize minimum caustic soda usage. Refer to the block scheme on Figure 3.2.2. The emphasis will be on meeting the product specification. For chitosan these are: degree of deacetylation, viscosity and particle size. Refer to Table 3.3.4 for product specifications.

The plant will be build in Morocco, Tangier as shrimps caught in the North Sea in the Netherlands are transported to Morocco to be peeled and packed before shipped back again for commercial use. About 1 % Benzoic acid is added to the shrimps as a preservative and generally 200 tones of shrimp shells are produced weekly. On this basis, the shrimp waste are crushed to about 1 mm and washed with ethanol to remove the benzoic acid. Crushing is required so that the size of the shells are reasonable for effective demineralization and deproteinization as well as to normalize the product size at the end of the process. Benzoic acid has to be removed in order to sell the protein fraction extracted from the shells as farm feedstock. After benzoic acid removal, chitin will be isolated by reactions with lactic acid. After separating chitin by filtration, purification of the chitin is carried out. The purification step is essential to allow deacetylation of chitin to be carried out to a greater extent and hence, increases the quality of the product. In this last phase, concentrated caustic soda will be applied to achieve the required specifications. Finally chitosan produced will be about 90 % deacetylated. The chitosan will be washed and filtered (NaOH rich filtrate) and then dried to give the high grade chitosan. Finally, the chitosan flakes are sieved and crushed to a product size of about 40-60 mesh. Product specifications are listed on Table 3.3.4. The Chitosan produced will be of medical grade and have very high economical value. The whole process is continuous.

This process is relatively a clean process, i.e. it does not produce hazardous materials. The only problem encountered is the disposal of highly alkaline NaOH. Chapter 9 discusses issues with waste streams. Almost all waste produced are recycled off site. Even NaOH is recycled, by means of electrolysis or electrochemical membranes. Generally, solvents are recycled, benzoic acid crystallized and acids neutralized.


CPD 3264 1-3

During the design of the plant, major obstacles were faced. They are mainly to determine the shrimp shell composition, the kinetics of the reactions in each reactor and finding the pure component and thermodynamic properties of chitin, chitosan, proteins, lipids and Astaxanthin. The shrimp shell composition is based on averaged values from various journals (Appendix A.3). The shrimp shell composition is a major factor in determining the reaction and size of the whole plant. Hence, it must be noted that a more thorough investigation should be done on the analysis of shrimp shell composition if a pilot plant were to be built. We have estimated the kinetics from lab scaled investigations. The order of reaction, activation energy and rate constants are determined from experimental data. The properties of chitin are estimated by ASPEN functional group, proteins are taken as leucine, lipids and Asthaxanthin as stearic acid.


CPD 3264 1-4

REFERENCES

[1] http://www.st.nmfs.gov/st1/fus/fus98/world/w-specie.pdf [2] www.ill.cri.nz , March 2001 [3] www.sigma-aldrich.com [4] L. Henry Larry, Biomaterial, A forecast for the future, Biomaterials 19, 1998 [5] Hall, G.M. Silva,S.D. Biotechnology 1994, pp.633 - 638 [6]Baustita, J. Jover, M., Process Biochemistry, 37, 2001, pp. 229 - 234 [7] Tsigous , I. Martinou, A., Trends in Biotechnology, Vol. 18, 2000, pp.305 – 312 [8] No, H.K. Cho, Y.I., Journal of Agricultural and Food Chemistry, Vol. 48, No. 6, 2000, pp.2625–2627


CPD 3264 2-1

Chapter 2. Process Options & Selection

2.1 Process concept chosen

1. Pretreatment

The crude shrimp shells are first pretreated. The shells are crushed to produce smaller particles and also washed with ethanol to wash off benzoic acid (preservative). Crushing is needed, to about 1 mm, to enhance effective demineralization and deproteinization process and to normalize the product size at the end of the process. Benzoic acid is removed using ethanol because of its high solubility and ease of separation. The recovery of ethanol is done with an evaporator at 1 atm and 87oC. This pressure and temperature is chosen as the minimum conditions for good separation based on a model in ASPEN PLUS 10.2. Because of water and ethanol azeotrope, the ethanol used in the extraction process is of 75 % purity, for the ease of solvent recovery. Thermodynamic properties are listed in Chapter 4. An alternative to ethanol would be ethyl ether, which shows high solubility of benzoic acid [1]. However this material is highly toxic, flammable and explosive.

2. Enzymatic Conversion of shrimp shells to chitin

Chitin is purified from shrimp shells by demineralization and deproteinization of the shells. There are basically four main methods to convert shrimp shells to chitin. Other than chemical treatment, this can be done either by the aid of bacteria, fungi or purified enzymes. Table 2.1.1 shows the advantages and disadvantages of each process.

With the main concern of a product quality, cost and the environment, modified enzymatic process via bacteria fermentation is chosen. The other processes are phased out because purified enzyme process is too expensive, conventional method too harsh and the fungi fermentation too novel. The bacteria strain used is Lactobacillus sp.B2. This bacteria is chosen because of its homo-fermentative feature; meaning it only produces one product, i.e. lactic acid. Many other strains of Lactobacillus bacteria are hetero-fermentative, which means they produce other side products like ethanol, acetate and CO2. This would lower the yield of lactic acid based on glucose as the carbon source.

The main strategy is acidification by lactic acid produced during fermentation. But, instead of using in-situ fermentation and deproteinization demineralization concept [7,9], separate fermentation and demineralization reaction concept is introduced here. With reference to the setup on Figure 3.2.2, lactic acid is first produced in a fermentor. The lactic acid produced will be separated from biomass by a microfilter and transported to a storage tank, before continuously fed to shrimp shells for demineralization and deproteinization. Lactic acid reacts with minerals (CaCO3) producing Calcium lactate, which is soluble, and also controls the pH of the reaction. [7]. Deproteinization is carried out with proteolytic enzymes naturally presents in the shells (marine proteases) [2]. Astaxanthin, a carotenoid pigment found in shrimp shells is recovered with the protein hydrolysate. This pigment is very valuable mainly in the medical field, and hence has a high sale value [3].

The chitin from the fermentation section is then further purified with weak HCl to dissolve more minerals and protein from the solid chitin.


CPD 3264 2-2

Table 2.1.1: Advantages and Disadvantages of various chitin preparation processes Advantages Disadvantages Reference Chemical Treatment HCl and NaOH solutions 100C, pH 1-13

1.Easy 2.Full developed (proven)

1.Harsh conditions reduces the quality of chitin

2.Consumes large amounts of acids and alkali

3.Environmental unfriendly 4. Protein recovery is impossible

[4]

Fungi fermentation e.g. Aspergillus niger and Pseudomonas maltophilia 37C, pH 7

1.Reduction of acid and alkali usage

2.Chitin based fungi contributes to more chitin produces

3.Use of hydrolyzed proteins as a nitrogen source

4.Quality of chitin retained 5.Recovery of astaxanthin

1.Novel process–little knowledge is known

2.Chitin from fungi have different properties than from shrimp shells, further treatment is required

3. pH sensitive

[5]

Purified enzymes e.g. protease (Alcalase) 40C, pH 4-5


2.Recovery of protein hydrolysate and astaxanthin

3.Quality of chitin is retained

1. Purification of enzymes from microorganism culture or purchasing the enzymes is very expensive

2. Further treatment with acids and alkali is required for a purer chitin

3. pH sensitive 4.Separate process for

deproteinization and demineralization

[6]

Bacteria fermentation e.g. lactobacillus sp B2 , lactobacillus plantarum 30C, pH 4.5-6


2.Recovery of protein hydrolysate and astaxanthin

3.Quality of chitin is retained 4. Well established process with

successful pilot plants running 5.Demineralization and deproteini-

zation simultaneously

1. pH sensitive 2. Further treatment with acids and

alkali is needed for purer chitin

[7], [8], [9]

3. Chitin deacetylation

In chitin deacetylation, there are few possibilities including enzymatic routes. Table 2.1.2 shows the main advantages and disadvantages of these methods.

For this section, chemical treatment under autoclaving conditions is chosen because of the advantages listed below. The conventional method is phased out because this process degrades chitosan quality and as for Chitin deacetylase (CDA) process, the isolation of CDA from microorganisms is expensive and time consuming.


CPD 3264 2-3

Table 2.1.2: Advantages and Disadvantages of various chitin deacetylation processes Advantages Disadvantages Reference Conventional chemical treatment with concentrated HCl/NaOH 100 C, 12-14 pH

Developed process 1.Degradation of chitosan quality from hash conditions

2.Large amounts of concentrated acids and alkali are needed

3.Environmental unfriendly 4.Consumes large amount of

energy

[4]

Chitin deacetylase (CDA) e.g. from Mucor rouxii, Absidia coerulea, Aspergillus nidulans, Colletotrichum sp. 50 C, 4.5 pH

1.Reduced use of acids and alkali compared with the conventional method 2.High grade chitosan produced (high solubility)

1.Product inhibition 2.Pre-deacetylation with conc.

NaOH or extensive pre-treatment of chitin is needed for effective deacetylation by CDA

3.Isolation of CDA is expensive and time consuming

4. pH sensitive

[10], [11], [12]

Chemical treatment under autoclaving conditions (15 psi/121 C, 12-14 pH)

1. Reduced use of acids and alkali compared with the conventional method 2. No significant degradation of chitosan 3. Simple and cheap

1. Use of concentrated NaOH [13], [14]

After deacetylation of chitin to about 90 % in autoclaving conditions, the chitosan produced will be filtered to remove NaOH, washed with water to remove further impurities and finally dried to produce chitosan of particle size of 40-60 mesh. Final grinder unit is installed to insure the uniformity of particle size. The complete equipments and plant layout can be seen on the Process Flow Scheme (PFS) in Chapter 5 or a simplified version in the block scheme, Figure 3.2.2.

The whole process will be run continuously for ease of operation and economic reasons. Product quality, process controllability, safety, and flexibility are the main consideration. The main advantages are increased economical operation, less time is needed for start-up and shutdown, and often less maintenance is needed. Because the operating conditions are constant, fewer operators may be needed, and automatic control is more readily applied. It may be also more feasible to increase the scale of a continuous system, thus improving unit economy. Furthermore there is better quality control, as once the operating parameters are properly set, the continuous system will provide a more consistent product. However, a couple of disadvantages of continuous process is the increase in complexity of equipment and the need for more thorough planning, usually requiring pilot-scale testing.

Investigations for heat integration is carried out for sections where heating and cooling of process streams are required. Since most of the process streams are at 25C, only two streams needs consideration for heat integration. From the PFS, stream <206>, the input stream to C201 Ethanol Evaporator and stream <408> the output from R401 deacetylation reactor should be considered. Stream <206> needs to be heated from 25C to 77C while stream <408> needs to be cooled from 121C to about 25C. Heat integration in detailed can be seen in Chapter 8.2.5.2.


CPD 3264 2-4

[1] Seidell,A. Solubilities of Organic Compounds, 3rd ed. Vol. II, 1941, pp.510 [2] Shirai, K. Legaretta, I.G., Serrano, G.R. Aspect of Protein Breakdown during the lactic acid fermentation of prawn waste, EUCLIS 2, 7th ICCC, Lyon, 1997

[3 ] www.astaxanthin.org, April 2001 [4] Roberts, G.A.F., Chitin Chemistry, MacMillan, 1992

[5] Wang, S.L., Chio, S.H. Enzyme and Microbial Technology, 22, 1998, p.629 – 633

[6] Gilberg, A. Stenberg, E. Process Biochemistry, 36, 2001, p.809 – 812

[7] Legarreta, I.G. Zakaria, Z., Hall, G.M., Lactic Acid Fermentation of Prawn Waste; Comparison of Commercial and Isolated Starter Culture, EUCHIS I, Drest, 1995

[8] Baustita, J. Jover, M., Process Biochemistry, 37, 2001, pp. 229 - 234

[9] Zakaria, Z. Hall, G.M., Shama, G. Process Biochemistry, 33, 1998, pp.1 – 6

[10] Tsigous , I. Martinou, A., Trends in Biotechnology, Vol. 18, 2000, pp.305 – 312 [11] Kolodziejska, I. Woojtasz-Pajak, A., Ogonowska, G., Sikorski, Z.E., Bulettin of The Sea Fisheries Institute, 2(150), 2000, pp.15-23

[12]Kolodziejska, I. Malesa-Ciecwierz, M., Lerska,A., Sikorski, Z.E, Journal of Food Biochemistry, 23, 1999, pp.45-47

[13] No, H.K. Cho, Y.I., Journal of Agricultural and Food Chemistry, Vol. 48, No. 6, 2000, pp.2625–2627

[14] Cho,Y.I., No,H.K., Journal of Chitin and Chitosan, 4(3), 1999, pp.152-155


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Chapter 3 : Basis of Design

3.1 Description of the design

In this design, chitin that is naturally 25 % deacetylated is extracted from shrimp shells and then deacetylated further to 90 % to produce high grade chitosan. The shrimp shells are first crushed to a specific particle size of about 1mm and then washed with ethanol-water mixture to remove 99 % of benzoic acid. Lactic acid, produced by fermentation in the process, is introduced to the shrimp shells and demineralization and deproteinization take places. Approximately 90 % of demineralization takes place in this first reactor. Crude chitin particles are purified with hydrochloric acid (HCl) for further demineralization (calcium carbonate) before deacetylation of chitin is carried out with concentrated sodium hydroxide (NaOH). 90 % of deacetylation is achieved in this unit with simultaneous deproteinization takes place. The 90% deacetylated chitosan particles are washed, filtered and dried. As the last step, dried particles are grinded to very small particles of about 50 mesh (50 micron). Ethanol used to remove benzoic acid is recovered while NaOH and HCl used are considered as waste stream that need to be treated before disposal. The benzoic acid slurry can be further purified and sold as a side product. However, the treatment of the waste streams will not be considered in the design. Please refer Table A.1.1, Appendix A.1 for summary of basic assumptions and design specifications.

3.2 Process Definition

3.2.1 Process Concepts Chosen

After the crushing of the shrimp shells, 75 % ethanol is used to extract benzoic acid from the shrimp shells in an extractor. Ethanol is recovered using an evaporator at 1 atm, 87 ºC. In lactic acid fermentation, lactic acid is first produced in at 1 atm, 30 ºC, separated from the biomass by micro filter and stored. Lactic acid is sent to chitin demineralization and deproteinization reactor at 1 atm 30 ºC. Chitin demineralization and deproteinization take place at 25 ºC and 1 atm. The proteolytic enzymes present in shrimp shells which catalyzes deprotenization reaction are heat sensitive therefore these reactions are carried out at low temperatures (25 ºC) is used. Purification of chitin is carried out with 0.5 N HCl at 1 atm adiabatically. Finally, the purified chitin is deacetylated using 45 % NaOH at a ratio of 10:1 weight per volume of solids. This NaOH also helps in the final deproteinization which occur simultaneously in deacetylation reactor. The product from this reactor is cooled, washed and filtered and dried at 40 ºC. Finally the particles are grinded to specific mesh size by grinder.


CPD 3264

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3.2.1.1 Reaction Stoichiometry

Complete reaction stoichiometry and catalysts used are presented in Table 3.2.1.

Table 3.2.1: Reaction Stoichiometry and Catalysts Employed Reaction Stoichiometry Catalyst Notes

Lactic Acid Fermentation

8.16 CH2O (aq) + 0.2 NH4+ (aq)

Glucose Ammonium CH1.8O0.5N0.2 (s) + 7.11 CH5/3O –1/3 (aq) + 2.62 H+ (aq) Biomass Lactic acid Hydrogen ions + 0.05 HCO3

- (aq) + 0.4 H2O (l) Bicarbonate Water

Lactobacillus sp. B2

Calculation in Appendix D.2

Lactic Acid demineralization

2 C3H6O3 (aq) + 1 CaCO3 (aq) 1 Ca (C3H5O3)2 (aq) Lactic acid Calcium carbonate Calcium lactate + H+ (aq)+ HCO3

- (aq) Hydrogen Bicarbonate

Calculation in Appendix A.2.a

Enzymatic deproteinization

n 2(Protein) (aq)+(n-1)H O(l) n Protein (l) Intestinal protease

Calculation in Appendix A.2.b

Chemical demineralization

2 HCl (aq) + 1 CaCO3 (s) 1 CaCl2 (aq) + H+ (aq) + HCO3

- (aq) Calculation in

Appendix A.2.c

Chemical deproteinization

n 2(Protein) (aq)+(n-1)H O(l) n Protein (l) NaOH Calculation in Appendix A.2.d

Chitin deacetylation

C8H13NO5 (s) + H2O (l) C6H11NO4 (s) +CH3COOH (aq) Chitin Water Chitosan Acetic acid

NaOH Calculation in Appendix A.2.e

3.2.1.2 Kinetics

3.2.1.2.1 Demineralization (Lactic acid)

Demineralization from shrimp shell takes place by reaction with lactic acid. [1]

3 3 3 2 2 2( ) 2 ( ) ( ) ( ) ( ) ( )CaCO s CH HCOHCOOH aq Ca CH HCOHCOO aq CO g H O aq (3.2.1)

Demineralization depends on concentration of lactic acid and fraction of minerals in the reactor. Therefore reaction rate can be described by

dM

k L Mdt

(3.2.2)

In which L represents lactic acid concentration [kg/m3], M is mineral fraction based on initial mineral mass in chitinous material [kg-mineral/kg-mineral initial], k is the rate constant, and are the degree of polynomial of lactic acid and mineral respectively.

Three different periods are observed from the experimental data. After a relatively short lag period of 6 hours, demineralization proceeded at a relatively steady rate until around 40 hours,


CPD 3264

3-3

and then reaction continued slowly towards the end of the experiment. Therefore we assume three periods (three different stages) exist for demineralization of chitinous material. k, , and is calculated in Appendix A.2.a. Then the reaction rates are described as follows.

First stage

0.3100 0.033742.71 10 dM

L Mdt

(3.2.3)

Second stage

0.4567 0.584041.27 10 dM

L Mdt

(3.2.4)

Third stage

1.7440.0126 dM

Mdt

(3.2.5)

3.2.1.2.2 Enzymatic Deproteinization

Deproteinization takes place by hydrogenation of protein, which is catalyzed by proteases. Tryptic like proteases, which exist in shrimp shells, are known to react with the protein by cutting the peptide link near the lysine.

General protein hydrolysis is described generally as follows. n 2(Protein) (aq)+(n-1)H O(l) n Protein (l) (3.2.6)

It is assumed that this reaction is depending on protein fraction. Further calculation is shown in Appendix A.2.b. Reaction kinetics is described as follows.

4.2910.0070

dPP

dt (3.2.7)

In which P is the fraction of protein based on mass in the chitinous material initially. Refer to Appendix A.2.b for calculation.

3.2.1.2.3 Chemical Demineralization (Hydrochloric acid)

Demineralization from shrimp shell is accomplished by extraction of calcium carbonate with dilute hydrochloric acid to form calcium chloride. [2]

3 2 2 2( ) 2 ( ) ( ) ( ) ( )CaCO s HCl aq CaCl aq CO g H O l (3.2.8)

Pseudo first-order reaction kinetics in terms of mineral fraction in is observed. The rate of reaction can be described as:


CPD 3264

3-4

23800-43.31 10 RT

dMA M e

dt

(3.2.9)

Where M represents mineral fraction [kg-mineral/kg-mineral initial] based on initial mineral mass, and A represents amount of HCl [N·l-solution/kg-solid]. Calculations are described in Appendix A.2.c.

3.2.1.2.4 Chemical Deproteinization (Co-currently with deacetylation in Sodium hydroxide)

Sodium hydroxide solution is used to remove protein from shrimp shell. Several possible covalent bonds might be involved in the chitin-protein link. Deproteinization from shrimp shell appears to have a two-stage first-order reaction kinetics. The considerable decline in deproteinization rate suggests that there is a change in mechanisms during deproteinization. The change in reaction rates occurs when the protein concentration becomes low. The inflection point is located between 6.4% -10.4 %, hence the protein concentration above 7% is taken as the first stage and below 7 % is taken as the second stage [3]. Refer to Appendix A.2.d for further calculations.

First Stage 35800

37.7 RTdP

B P edt

(3.2.10)

Second Stage 24760

-33.63 10 RTdP

B P edt

(3.2.11)

Where P represents fraction of protein based on mass in the chitinous material initially, and B represents amount of NaOH [N·ml-solution/g-solid].

3.2.1.2.5. Chemical Deacetylation

Chitosan is produced by deacetylation of chitin. These 2 polymers, chitosan and chitin, do not refer to uniquely defined compound but rather to belong a family of copolymers with various fractions of acetylated units of glucosamines. Chitosan is defined as having degree of deacetylation (D) higher than 60 %. Chitin is treated with a hot, concentrated solution of NaOH, and chitosan is produced as an insoluble precipitate [4].

Chitin Chitosan

Figure 3. 2.1 Chitin deacetylation


CPD 3264

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Overall reaction is simplified as hydrolysis of the acetyl group with production of acetic acid.

8 13 5 2 6 11 4 2 4 2( ) ( ) ( ) ( )C H NO s H O l C H NO s C H O aq (3.2.12)

The deacetylation of the chitin also behaves a pseudo first order reaction in terms of the number of acetyl group. (Due to abundant amount of water and NaOH, the reaction rate is described as function of D, which is degree of deacetylation.) Calculations are shown in Appendix A.2.e.

71700

64.10 10 (1 ) RTdD

D edt

(3.2.13)

3.2.2 Block Schemes of Chitosan Production

Figure 3.2.2 Process scheme diagram of chitosan production

45% NaOH 1:10 w/v

Fermentation broth

Water

N-source

Innoculum

Water

Shrimpshells

Ethanol

<10>

<15>

<17>

0.5 N HCl

1:5 w/v

Benzoic acid slurry

Chitosan

Waste water

(HCL)

Waste water (NaOH rich)

<1> <2> <3> <4>

<5>

<6>

<9>

<7>

<11>

<14>

<12>

<16>

<18>

<27>

<26>Crusher1 atm 25 C

S

Lactic AcidFermentor

1 atm 30 CL-S

Filtration.0.6 atm 25 C

L-S

Deacetylation2.3 atm 121 C

L-S

Washing : Extractor1 atm 25 C

L-S

Dryer0.05 atm 40 C

L-S

Ethanol Recovery:Distillation

1 atm 87 CL-S-V

Filtration &Wash

1 atm 25 CL-S

Filtration1 atm 25 C

L-S

Chitin Purification0.6 atm 25 C

L-S-V

<29>

<31>

<33>

<30>

S : Solid L: Liquid L-S: Liquid-Solid mixture L-S-V: Liquid-Solid-Vapor mixture

t/a : tonnes per year t/t : tonnes per 1 tonne of product

4555 t/a

0 t/a

120 t/a

10050 t/a 10050 t/a 9970 t/a

455 t/a

335 t/a

535 t/a

30070 t/a

200 t/a

3480 t/a

15085 t/a

26435 t/a

3635 t/a

18680 t/a

22550 t/a

3365 t/a

15315 t/a

1610 t/a

830 t/a

780 t/a

Deproteinization&

DemineralizationReactor1 atm 30 C

L-S-V

Lactic AcidStorage1 atm 30 C

L<19>

<24>

1

2

3

4

Microfilter1 atm 30 C

L

Grinder1 atm 25 C

S

780 t/a<8>

25915 t/a

<25>510 t/a

<28>40t/a

<13>

<20>28560 t/a

<22>20610 t/a

20610 t/a

<23>7950t/a

<32>27785t/a

Glucose16080 t/a

<21>25 t/a CO2 purge

CO2 purge

CO2 purge

5.8 t/t

21 t/t

0 t/t

0.15 t/t

13 t/t

19 t/t

4.5 t/t

29 t/t

36 t/t

1.1 t/t

20 t/t

0.25 t/t

0.05 t/t

34 t/t

0.65 t/t

0.03 t/t


CPD 3264

3-6

Arrows describe the streams and the main streams are drawn by bold arrow, which begin with shrimp shell and end up with chitosan. Blocks in figure show the operating units in the process and large box with dot shows battery limit of our project. In our projects mainly 14 units, which are drawn in block scheme, are inside battery limit. Besides these 15 units, pumps, heat exchangers, conveyers, pipes are involved in our design. Four Circles with numbers show sections of process. Sections can be described as follows.

1. Lactic acid production 2. Pretreatment (Crushing and benzoic acid extraction) 3. Demineralization and deproteinization 4. Chitin deacetylation and treatment for manufacturing

The streams on left side of the diagram are feed and those on right side are outlet of the process. Shrimp shells are sent from shrimp peeling industry. The rest of the raw materials are purchased.

Chitosan is our main product, and it is manufactured to be medical grade in this process.

Benzoic acid slurry is further purified to obtain benzoic acid. Benzoic acid can be used in the shrimp industry as preservative again or sold. Filtrate from the first filter, which contains lactic acid, proteins, carbohydrates, calcium lactate, lipids plus asthaxanthin, has potential to be farm feed stock. Therefore it is also sent to another purification process and can be sold as farm feedstock.

CO2 gas is generally not toxic nor hazardous, hence treatment for this component is not needed. Acidic water and alkaline water are combined together to neutralize. However amount of alkaline material is much larger than the acidic material, therefore combining stream need further treatment, such as dilution, neutralization. As an option, alkaline material, NaOH, is recovered to the process through special treatment. Please refer to Chapter 9, waste treatment.

3.2.3 Thermodynamic and pure component properties

As it is mentioned in Chapter 1, it is difficult to get the thermodynamic and pure component properties of chitin and chitosan. These data are estimated by ASPEN functional group. Carbohydrates, protein, and lipids are generic names of the components, and they do not have exact structure. The properties of these components are estimated by substituting components with conventional ones. Carbohydrates are represented by glucose, proteins are taken as leucine, which has closest molecular weigh to average of 9 major amines, lipids and asthaxanthin as stearic acid. These properties are also simulated from ASPEN by representing components as mentioned above. NRTL is chosen as main properties method. Please refer to Chapter 4, thermodynamics, and Chapter 8.1, integration with ASPEN.

Thermodynamic properties and pure component properties from literature are listed in Table 3.2.1 and Table 3.2.2. Comparison of literature data and simulated data are described at Chapter 4.3.


CPD 3264

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Table 3.2.1 List of Thermodynamics Properties [5,6]

Component Name Technological Data

Cas-No Formula pKa Cp values (J/mol K) Heats of formation (kJ/mol)

Design 25 C Cp = A + BT + CT2+ DT3 + ET4 Hf = A + BT + CT2

A B C D E A B C

Acetic acid 64-19-7 C2H4O2 4.734 -18.944 1.0971 -2.89E-03 2.93E-06 0 -422.584 -4.84E-02 2.33E-05

Ammonium sulfate 7783-20-2 (NH4)2SO4 n/a 103.554 2.81E-01 0 0 0 -1174.3 (aq) 25 C

Astaxanthin 472-61-7 C40H54O4 n/a n/a n/a

Benzoic acid 65-85-0 C7H6O2 4.2 -158.917 2.3735 -4.83E-03 3.69E-06 0 -266.14 -9.36E-02 4.17E-05

Calcium chloride 10043-52-4 CaCl2 n/a 72.867 at 25 C -877.1 (aq) 25 C

Calcium carbonate 471-34-1 CaCO3 n/a 104.516 2.19E-02 -2.59E-06 0 0 -1220.0 (aq) 25 C

Calcium lactate 814-80-2 C6H10CaO6 n/a n/a n/a

Chitin 1398-61-4 C8H13NO5 n/a n/a n/a

Chitosan 9012-76-4 C6H11NO4 n/a n/a

Carbon dioxide 124-38-9 CO2 6.352 27.437 4.23E-02 -1.96E-05 4.00E-09 -2.99E-13 -393.523 (gas) 25 C

Ethanol 64-17-5 C2H6O 15.5 59.342 3.64E-01 -1.22E-03 1.80E-06 0 -2.17E+02 -6.96E-02 3.17E-05

Glucose 50-99-7 C6H12O6 12.28 n/a -1264 (aq) 25 C Hydrochloric acid 7647-01-0 HCl -6.2 73.993 -1.29E-01 -7.90E-05 2.64E-06 0 -167.2 (aq) 25 C

Sulfuric acid 7664-93-9 H2SO4 83.68 at 25 C -735.12 (s) 25 C

Lactic acid 50-21-5 C3H6O3 3.858 n/a -604.002 -6.80E-02 3.55E-05

Lipids (Stearic acid) 57-11-4 C18H36O2 501.55 at 25 C -947.2 (l) 25 C Sodium chloride 7647-14-5 NaCl 50.50 at 25 C -411.1 (s) 25 C

Sodium hydroxide 1310-73-2 NaOH n/a 87.639 -4.84E-04 -4.54E-06 1.19E-09 0.00E+00 -469.61 (aq) 25 C

Nitrogen 7727-37-9 N2 28.87 at 25 C 0

Oxygen 7782-44-7 O2 28.91 at 25 C 0

Protein(Leucine) 61-90-5 C6H13NO2 2.223 191 at 25 C -648.9 (s) 25 C

Water 7732-18-5 H2O 13.995 92.053 -4.00E-02 -2.11E-04 5.35E-07 0 -286.410 (aq) 25 C


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Table 3.2.2 List of Pure Component Properties [7,8]

Technological Data Medical Data

Formula Mol. Boiling Melting Density MAC LD50 NotesDesign Weight Point Point of Liquid value Oral

Systematic (1) (1) (2) (3)g/mol oC oC kg/m3 mg/m3 g/kg

Acetic acid C2H4O2 60.052 117.9 16.6 1044.6 25 3.53

Ammonium sulfate (NH4)2SO4 132.16 n/a 280 1769 n/a 2.8

Astaxanthin C40H54O4 596.8 n/a 178 n/a n/a 5 (6)

Benzoic acid C7H6O2 122.12 249.2 122.4 1265.9 15n/a 2

Calcium chloride CaCl2 110.986 1600 782 2160 n/a 0.05-1

Calcium carbonate CaCO3 100.087 n/a 825-1330 2710-2830 10 0.05-6.45

Calcium lactate C6H10CaO6 218.221 n/a 120 640 10 n/a

Chitin C8H13NO5 203.194 n/a n/a 100-400 n/a 16

Chitosan C6H11NO4 161.157 n/a 1727 500-690 n/a 10

Carbon dioxide CO2 44.01 -78.4 -56.6 1530 9000 n/a

Ethanol C2H6O 46.07 78.3 -114.1 789 1000 7.06

Glucose C6H12O6 180.16 4352 150 1562 18n/a 35

Hydrochloric acid HCl 36.461 -85 -114.2 1490 8 0.9Sulfuric acid H2SO4 98.08 280 3 1840

Lactic acid C3H6O3 90.079 122 17 1201 n/a 3.543

Lipids (Stearic acid) C18H36O2 284.48 361 69.3 847Sodium chloride NaCl 58.44 1413 801 2165

Sodium hydroxide NaOH 39.997 1388 323 2130 2 0.14-0.34 Nitrogen N2 28.012 -195.86 -209.95 0.967

Oxygen O2 18.02 -183.17 -218.4 1.1053

Protein(Leucine) C6H13NO2 123.54 sublime n/a 1371.5 n/a 5.8075 (5)

Water H2O 18.02 100 0 995 n/a n/aIons

Hydrogen ions H+ 1.0079 n/a n/a n/a n/a n/a

Sulphate ions SO42- 96.0576 280 3 1.8 1 2.14

Bicarbonate HCO3- 61.0171 n/a n/a n/a n/a n/a

Protein properties top 9 amino acid)Alanine C3H7NO2 89.09 - 297 1437 n/a n/a (7)

Arginine C6H14N4O2 174.2 805 244 - n/a n/a (7)

Isoleucine C6H13NO2 131.17 - 284 - n/a 6.8 (7)

Glutamic acid C5H9NO4 147.13 175 sub 160 1538 n/a n/a (7)

Glycine C2H5NO2 75.07 - 290 1161 n/a 7.93 (7)

Leucine C6H13NO2 131.17 sublime 293 1293 n/a 5.4

Lysine C6H14N2O2 146.19 - 224 - n/a n/a (7)

Serine C3H7NO3 105.09 150 sub 228 1600 n/a n/a (7)

Threonine C4H9NO3 119.12 - 256 - n/a 3.1 (7)

valine C5H11NO2 117.15 sublime 315 1230 n/a n/aAverage - 123.54 - 259.1 1371.5 n/a 5.8075Notes :

N/a (4)

(1) (5)(2)

(3) (7)

Density at 25 oC, unless specified otherwise (6) Properties of beta-carotene

Oral in g 's for a rat Decompose at melting point

not applicable Properties of Glucose

At 101.3 kPa Average value of amino acids

Component Name

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

1

Ions

Protein properties (top 9 amino acid)

(6)


CPD 3264 3-9

3.3 Basic Assumptions

3.3.1 Plant Capacity and Location

All shrimp shells used in this process are supplied from the biggest shrimp peeling industry in Morocco that generates about 200 ton/week of shrimp shell as waste. The capacity of the proposed plant is 10,050 tonnes of shrimp shells per year, hence 780 tonne of chitosan is produced per year, based on our assumptions. Location of plant is Tangier, in Morocco, where the peeling industry is located.

3.3.2 Battery Limit

3.3.2.1 Main units description

Battery limit is set as it is shown as box in Block scheme, Figure 3.2.2, hence 14 main units are involved in our battery limits. The main conditions of main units inside battery limits are listed in Table 3.2.1. Please refer Chapter 5 for process structure and description.

Table 3.3.1 Main Units

Unit Pressure Temperature Valid states Process flowscheme number

[atm] [ºC]

1 Lactic acid fermentor 1 30 L-S R101, R102

Biomass recycle microfilter 1 30 L-S S101, S102

Lactic acid buffer tank 1 30 L T101

2 Shrimp shell crusher 1 25 S A201

Benzoic acid extractor 1 25 L-S S201

Ethanol recovery distillation 1 87 V-L-S C201

3 Chitin deproteinization demineralization

1 25 V-L-S R301

Chitin purification 1 25-40 V-L-S R302

Drum filter 1 1 25 L-S S301

Drum filetr 2 1 40 L-S S302

4 Chitin deacetylation 2.3 121 L-S R401

Chitin drum filter 0.6 25 L-S S401

Product dryer 0.05 40 V-L-S D401

Chitosan grinder 1 25 S A401


CPD 3264 3-10

3.3.2.2 Facilities

Following facilities are assumed to be available from outside the battery limit. Their prices are listed in Table 3.3.2. As reference, product prices are also listed in this Table.

Feed stock: Shrimp waste, glucose, ethanol, hydrochloric acid, sodium hydroxide, ammonium sulphate, water.

Utility: MP steam (3 atm 133 C), LP steam (10 atm, 180 C), cooling water (25-30 C),

chilled water (5-13 C), electricity

Lactobacillus sp. B2 is used as catalyst of the fermentation to produce lactic acid. Lactobacillus sp. B2 is assumed to be prepared in laboratory. This laboratory is not in our battery limit, however cost for this laboratory is considered. Please refer chapter 11 for further details.

Table 3.3.2 List of Component and Prices

Price €/ton

Feedstock Shrimp waste -

Glucose 453.8

Ethanol 1,064.10

Hydloric acid 198.1

Sodium hydroxide 360.8

Ammonium sulphate 25.6

Process Water 0.7

Product Chitosan 453,000

Fermentation broth (Calcium lactate + Protein

hydrolysate)

480

Catalyst Lactobacillus sp. B2 (Considered in laboratory cost)

Utility MP Steam 31.613

LP Steam 27.227

Cooling Water 0.045

Chilled Water 0.907

Electricity 0.046€ / kWh


CPD 3264 3-11

3.3.2.3 Shrimp shell properties and product specification

The raw material used is shrimp shells from cold water shrimps, which are caught in North Sea. Generally cold water shrimp contains more proteins and chitin compared with tropical water shrimps. Our process design is based on average shrimp shell properties. Refer to Appendix A Table A.3.1 for the list of shrimp shell components from some sources. Shrimp shell properties are described as Table 3.3.3. Concentrations of chitin, protein, minerals and other solids are described in dry basis.

Table 3.3.3 Shrimp Shell Properties

Water 60 % Bounded 50 % Free 50 % Benzoic acid 1 % Prawn shells/solids 39 % Protein 40.2 % Chitin (25 % deacetylated) 20.8 % Minerals/Ash 34.0 % Other Carbohydrates 2 % Astaxanthin 0.06 %

Lipids 2.94 %

Chitosan quality is determined by viscosity, degree of deacetylation and particle size distribution. The higher the molecular weight and molecular mass, and the more soluble chitosan is, the more applications exist in industry. Design product specification is described in Table 3.3.3 with commercial specifications. As it is mentioned in chapter 1, high grade chitosan is aim to be produced in our design. Design specifications are determined from the laboratory experiment of deacetylation. [9]

Table 3.3.4 Product Specification Commercial specification

(technical grade) [10] Commercial

Specification [9] Design product specification [9]

Degree of deacetylation 80 – 100% 87.6% 90% Molecular mass 1304 kDa 1560 kDa Viscosity 5 – 500 cP 143 cP 2025 cP Nitrogen content 7.40 % 7.42 % Particle size 25 – 100 mesh 50 mesh


CPD 3264 3-12

3.3.3 Input Output Streams and Diagram

Stream conditions and flow rates are summarized in Table 3.3.5. Input and output diagram across the battery limit is shown in Figure 3.3.1.

Table 3.3.5 Input Output Diagram of Chitin and Chitosan Synthesis Process

Stream Number

Stream Label Stream Condition

Flow rate (tonnes/year)

Yield (tonnes/

tonne-product)

Input <1> Shrimp shell 25 C, 1 atm 10050 13

<12> Ethanol* 25 C, 1 atm 120 0.15

<17> N-source* 30 C, 1 atm 4555 5.8

<18> Glucose* 25 C, 1 atm 16080 21

<19> Innoculum 25 C, 1 atm 0 0

<27> Water, hydrochloric acid* 25 C, 1 atm 15085 19

<30> Water 25 C, 1 atm 3480 4.5

<31> Water, sodium hydroxide* 25 C, 1 atm 22550 29

Product <11> Chitosan 25 C, 1 atm 780 1

<26> Fermentation broth* 25 C, 1 atm 26435 34

Waste <16> Benzoic acid slurry 87 C, 1 atm 200 0.25

<21> CO2 Purge 25 C, 1 atm 25 0.03

<25> CO2 Purge 25 C, 1 atm 510 0.65

<28> CO2 Purge 25 C-40 C, 1 atm

40 0.05

<29> Waste water, HCl 25 C, 1 atm 15315 20

<33> Evaporated water 60 C, 1 atm 830 1.1

<32> Waste water, NaOH rich 100 C, 1 atm 27785 36

Utility - MP Steam 180 C, 10 atm 705.3 0.90

- LP Steam 133 C, 3 atm 1479.1 1.9

- Cooling Water 25-30 C, 1atm 98864.9 130

- Chilled Water 5-15 C, 1 atm 104688 130

- Electricity - 364420 kWh/a 470 k Wh

*These streams are consists of water and other components, and they effects on the economic calculation. The compositions of these streams are listed below in Table 3.3.6.

Ethanol feed is determined as 75 % purity, which supply enough extraction of benzoic acid. Refer to Appendix D.7 for details. Concentration of ammonium sulphate in determined by simulation of fermentation. 20 % is considered as safety factor, therefore 20 % more ammonium sulphate is fed than requirement (stoichiometry). Ratio of water to ammonium sulphate is set to be high to ensure that ammonium sulphate is soluble into the water. Concentration of glucose is determined by consumption. It is set that 99.9 % of glucose consumption by the reaction. Refer to Chapter 8.2.1 and Appendix D.2 for details. Concentration of hydrochloric acid is set as 0.5 N, which is required for


CPD 3264 3-13

chitin demineralization reaction. Concentration of sodium hydroxide is set to be 45 wt%. This is due to the reaction restriction for deacetylation of chitin.

Table 3.3.6 Solution Compositions

Stream Stream Label Components Flow rate Yield (tonnes/

Number (tonnes/year) tonne-product)

<12> Ethanol Water 40 0.05

Ethanol 80 0.1

<17> N-source Water 4380 5.6

Ammonium sulphate 175 2.2

<18> Glucose Water 13140 17

Glucose 2940 3.8

<27> Water, hydrochloric acid Water 14810 19

Hydrochloric acid 275 0.35

<31> Water, sodium hydroxide Water 12400 16

Sodium hydroxide 10150 13

<26> Fermentation broth Water 20285 26

Fermentation broth 6150 8

Figure 3.3.1 Input Output Diagram

Waste water N

aOH

ri ch < 32>W

aste water NaO

H

ri ch < 32>M

P SteamM

P Steam

Cool ing waterCool ing water

Electrici tyElectrici ty

Evaporated w ater

< 33>Evaporated w ater

< 33>

Innoculum <19>

Glucose <18>

Ethanol <12>

Shrimp shells <1>

Water, hydrochloric acid <27>

Water, sodium Hydroxide <31>

Chitosan <11>Chitosan <11>

<26>Fermentation broth <26>Fermentation broth

Chitin and Chitosan

Synthesis

Water <30>

N-source <17>

Benzoic aci d sl urry <16Benzoic aci d sl urry <16

CO2 purge <21 <25 > <2 8>>

CO2 purge <21 <25 > <2 8>>

Waste water, H

CL <29>W

aste water, HCL <29>

LP SteamLP Steam

Chil led waterChil led water


CPD 3264 3-14

3.4 Economic Evaluation

Margin is total value (products, OUT)-total value (Feedstock’s, process chemicals, IN). Feedstock’s, process chemicals, IN, and products, OUT, are summarized in Table 3.4.1.

Table 3.4.1 Material Balances and Economic Evaluation

RAW MATERIALS FROM PFS-MATERIAL BALANCES

IN/OUT Name Stream No Tons/a Price million € per

annum €/ton

IN Feed Stocks Shrimp Shells <1> 10,050 - -

Glucose <18> 2,940 454 1.33

Ammonium Sulphate <17> 176 26 0.005

Ethanol <12> 83 1,064 0.088

HCL <27> 275 198 0.054

NaOH <31> 10,147 361 3.66

Process Water <18><27> <30><31>

482,448 0.7 0.033

Total IN 71,915 5.2

OUT Product Chitosan <11> 780 453,000 353

Fermentation broth <26> 6,151.00 480 2.95

Waste CO2 <21><25><28> 575

Benzoic Acid stream <16> 200

Water (with hydrolysate)

<26> 20,285.40

Waste water, HCl <29> 15,314.50 Waste water, NaOH

rich <32> 27,783.20

Evaporated water <31> 829.6

Total OUT 71,915 356.3

IN-OUT 0 351.1

Margin of our process is calculated as 351 million € per annum. It was 279 million € per annum in the BOD for the review meeting. It is summarized in Table 3.4.2.


CPD 3264 3-15

Table 3.4.2 Margin Comparison

*BOD is the first BOD review meeting report, and Final represents this report.

The reason of this difference is mainly from change in assumption for shrimp shells compositions. Some sources, which cannot be added up to 1, are normalized to 1, and calculation is based on average. Chitin content was 17.5 % for BOD and is 20.5 % for final report. Because of this change feed stocks cost have increased significantly. Proteins, and minerals contents also have increased, from 34.6 % and 32.4 % to 40.2 % and 34 %, respectively. Owing to this changes in assumption, the requirements of hydrochloric acid and sodium hydroxide, which counts for raw materials, have been also increased.

This process has very high margin, therefore the effect of capital costs are almost negligible. Please refer Chapter 11 for details calculation of economics. Main reason for this big margin is raw material, shrimp shells, is assumed to be supplied free of charge.

Feed Stocks Cost million €

per annum

Raw Materials million €

per annum

Margin million € per

annum BOD* 284 4.7 279 Final 356 5.2 351


CPD 3264 3-16

REFERENCES

[1] J.Bautista, M.Jover, Process Biochemistry, 37, 2001, pp229-234 [2] No,H.K., Hur,E.Y., Journal of Agricultural and Food Chemistry, 46(9), 1998, pp. 3844-3846

[3] Chang,k.L. Tsai,G., Journal of Agriculutral and Food Chemistry, 45, 1997, pp.1900-1904

[4] I Kolodziejska, A Wojtasz-Pajak, Bulletin of The Sea Fisheries Institute, 2 (150), 2000, 15-24 [5] Yaurs,C.L. Chemical Properties Handbook, McGraw Hill, 1999

[6] Lide,D.R. CRC Handbook of Chemistry & Physics, 81st ed. 2000-2001

[7] Chemiekaarten

[8] Sax’s Dangerous Properties of Industrial Materials

[9]No, H.K.,Hur, E.Y., Journal of Agricultural and Food Chemistry, 48, 2000, p. 2625 - 2627 [10] www.chitin.org, 2001


CPD 3264 4-1

Chapter 4 : Thermodynamics 4.1 Thermodynamics general concept In our designing process, some components exist as solid, e.g. chitin, chitosan, calcium carbonate, benzoic acid, insoluble protein, and glucose. Chitin, chitosan, and protein are polymers. Chitin and chitosan are insoluble to the water, whereas chitosan becomes soluble only when water is mild acidic. Therefore in this project, it is assumed that the solubilities of chitin and chitosan are negligible. It means that chitin and chitosan exist as solids in whole the process. Hence, only heat of formations and heat capacities are the required properties for chitin and chitosan, because they are not separated under any chemical equilibrium, such as solubility or melting point. In general, properties of solid, such as porosity and particle size, effect on reaction rate. However the reaction kinetics is also overall kinetics, which involves the solidness of the material. The kinetics was interpreted from articles; the experiments of which had been done through the reaction of particles. Moreover, we are unable to find further kinetics information that might help to consider solidness. By using this reaction kinetics, it is not necessary to consider further solidness, such as porosity, particle size, in ASPEN simulation. Therefore in the main simulation, we treat all the components as liquid, and also because ASPEN shows difficulty to estimate components as solids. Chitin, chitosan, protein, and other carbohydrates are polymers. In our simulation, they are treated as the assembly of the segments, because total mass is more essential than chain length of polymer. Chain length of polymer is important factor to illustrate chitin/chitosan product quality, but we do not take into account the decomposition of polymer in our project. To get the thermodynamics data, such as heat of formation, or heat capacity, it is sufficient to simulate them as assembly of segments, which exist as liquid. While solidness of the components is necessary to simulate the filter, which is solid and liquid separation, sub simulations are carried out for the filters. The results are transferred to the main simulation. Refer to Chapter 8.1. 4.2 Thermodynamics Model In our process, there are polar and non-polar components. Therefore, the activity coefficient model should be used, which is applicable for highly non-ideal mixture. The activity coefficient method is a combination of two different methods, one to describe liquid phase and the other to calculate vapor phase. Non Random Two Liquid method (NRTL), which is one of the activity coefficient models, can handle any combination of polar and non-polar compounds, up to very strong non-ideality. It is recommended for highly non-ideal chemical systems, and can be used for vapor-liquid equilibrium (VLE) and liquid-liquid equilibrium (LLE) applications. The NRTL model can describe VLE and LLE of strongly non-ideal solutions. The model requires binary parameters. Many binary parameters for VLE and LLE, from literature and from regression of experimental data, are included in the Aspen Plus databanks. The only restriction of this method is that parameters should be fitted in the temperature, pressure, and composition range of operation, and no components should be close to its critical temperature. Our process operation conditions are not severe, therefore this method is proper to apply.


CPD 3264 4-2

We have tried several property methods in ASPEN plus simulation, such as Wilson or Van Laar, however they have less data in ASPEN plus databanks and gave us errors. From these practical problems of other methods, NRTL is preferred. For vapor phase, it is treated by ideal gas method. No complexes are formed therefore it is not necessary to introduce other method. Non-condensables, such as N2, CO2, do not exist as a pure liquid and therefore it is not possible to use as activity coefficient model when such a component is present. However, non-condensables, such as N2, CO2, are minor components in our process and NRTL is the most suitable method for the rest of components. In NRTL, the solubility of CO2 is estimated rather higher than the literature data. [1] Therefore, the solubility of CO2 is compensated by manually applying these data in simulation. Extra component separation units are introduced in ASPEN simulation to apply these data manually. Please refer to Chapter 8.1 for integration of simulation. 4.3 Validation of Property Method 4.3.1 Properties Comparison It is suggested to check boiling point if the pure component against values from literature. Simulated boiling points are listed in Table 4.3.1, with data from literature.

Table 4.3.1 Comparison of boiling point Except the polymers, such as chitin, chitosan, and glucose, the results are rather comparable.

Boiling point Boiling point ºC (Literature) ºC (ASPEN)

Acetic acid 117.9 117.9 Ammonium sulfate - 68.75

Benzoic acid 249.2 249.25 Calcium chloride 1600 1935.45

Calcium carbonate - 46.44 Calcium lactate - 539.43

Chitin - 366.84 Chitosan 1727 351.58

Carbon dioxide -78.4 -78.45 Ethanol 78.3 78.29 Glucose - 343.85 Water 100 100

Hydrochloric acid -85 -85 Sulfuric acid 280 336.85 Lactic acid 122 216.85

Lipids (Stearic acid) 284.5 375.2 Sodium chloride 1413 1465

Sodium hydroxide 1388 1556.85 Nitrogen -183 -195.806 Oxygen -218.4 -182.962

Protein (Leucine) 293 280.69


CPD 3264 4-3

In our simulation, there are no phase changes for these polymers, because our maximum operating temperature is 121 ºC. (Some of them become soluble but it is not phase change) Further comparisons are done in Appendix B. Please refer Table B.1, Appendix B for heat of formation and Table B.2 for heat capacity. For the major components, results are relevant but some components shows large deviations from literature. These differences may cause some errors in calculation of heat duties. However, water is the main components for almost all the streams which are heat exchanged. Hence ASPEN plus can simulate the properties of water relevantly with NRTL, heat duty errors are estimated are not so large. 4.3.2 Operating Windows Operating windows of binary parameters of ASPEN are listed in Table 4.3.2.

Table 4.3.2 Operating Window

BENZACID ETHANOL ACETACID ACETACID CO2 Water Water Ethanol Water Water

Tlower (ºC) 64 25 35 20 0 Tupper(ºC) 116 100 116 230 200

The distillation of ethanol-water-benzoic acid is operated at 87 ºC. Therefore it is in the operating window of this property method. 4.4 VLE and solubility 4.4.1 Ethanol - water VLE We have chosen the NRTL method for the simulation of this system. Therefore ethanol and water are simulated as ideal gas. Ethanol, water binary VLE curve is drawn in Figure 4.4.1.

Figure 4.4.1 Ethanol Water VLE

Ethanol Massfraction

Tem

pera

ture

K

0 0.2 0.4 0.6 0.8 1

355

360

365

370

375

T-x 1.0 atm

T-y 1.0 atm


CPD 3264 4-4

From the literature we have the following sentence. ‘Ethanol forms a constant-boiling mixture, or azeotrope, with water that contains 95% ethanol and 5% water and that boils at 78.15°C; since the boiling point of this binary azeotrope is below that of pure ethanol, absolute ethanol cannot be obtained by simple distillation.’ [2] This result from ASPEN plus is comparable with this literature. 4.4.2 Benzoic acid–ethanol-water solubility Solubility of benzoic acid to water and ethanol is shown in Table 4.4.1. [3]

Table 4.4.1 Solubility of Benzoic Acid in Aqueous Solutions of Ethyl Alcohol at 25 C

Ethanol wt% Density of solvent Solubility Solubility

in solvent [kg/m3] [kg/m3-solvent] [kg/kg-solvent]

0 1000 3.4 0.0034 18.8 952.13 8.6 0.0090 31.5 922.31 73.8 0.0800 56.2 869.34 194.2 0.2234 75 832.94 299.7 0.3598

93.8 799.46 333.0 0.4165

As it is mentioned, we treat benzoic acid as liquid components in ASPEN simulation. Therefore these data are applied to ASPEN simulation manually. Please refer to Chapter 8.1 for integration of simulation. 4.5 Heat of reaction 4.5.1 Demineralization, deacetylation, and neutralization For these three reactions, heats of reactions are calculated in ASPEN plus.

Table 4.5.1 Heat of reaction Reaction Heat of reaction

J/kmol 1.Chemical Demineralization

CaCO3+2HCl>>CaCl2+CO2+H2O -8.96E+07 2.Enzymatic Demineralization

CaCO3+Lactic acid>Calcium Lactate+CO2+H2O -3.48E+09 3.Chemical Deacetylation

Chitin+H20>>Chitosan+Acetic Acid -7.48E+05 4.Neutralization

HCl+NaOH>>NaCL+H2O -2.52E+08 4.5.2 Deproteinization Protein hydrolysis is described generally as follows. n 2(Protein) (aq)+(n-1)H O(l) n Protein (l) (4.4.1)


CPD 3264 4-5

Lysine is one of the protein, and the hydrolysis of lysine takes place with the aid of enzyme, trypsin. n 2(L-lysine) (aq) + (n-1) H O(l) = n L-lysine(aq) (4.4.2) Heat of reaction is reported as –1340 J/mol at 298 K and pH 7.6. [4]


CPD 3264 4-6

1 http://sty.cc.yamaguchi-u.ac.jp/~speleo/Solution-Caves.html 2 http://www.encyclopedia.com/printablenew/04238.html 3 Solubilities of Organic Compounds, Atherton Seidell, 3rd Vol2 1941 4 http://wwwbmcd.nist.gov:8080/enzyme/ename.html


CPD 3264 5-1

Chapter 5 : Process Structure and Description 5.1 Criteria and Selections Explanation about unit operation types used, process conditions, and chemicals used will be presented here, as grouped in sections. 5.1.1 Lactic acid fermentation In this section, lactic acid that will be used as chemicals for shrimp shells demineralization, is produced. Fermentation method is chosen, utilizing Lactobacillus sp. B2, with glucose as substrate. Sequence of units is considered here, to ensure high production of lactic acid. The sequence consists of sterilizer, fermentor, microfilter, and storage tank. Sterilizer is a plate type heat exchanger, heating the medium until 140°C and then cooling it down to fermentation temperature. This step is necessary to kill harmful microorganism potentially inhibit the main process. Plate heat exchanger is chosen for ease of cleaning, as stream media has high viscosity and potentially clogs into the heat exchanger. Plate type also ensures high efficiency of heat transfer and requires more area and space compared to other type of heat exchanger. Basically, the ‘work horse’ chemostat (CSTR) is chosen for the fermentor. Continuous process at constant-controlled pH and T is chosen for the ease of operation, service, and control. Fermentation will be conducted at pH 5.5, 40°C as the result of process simulation optimization, which was done in Matlab (Appendix D.2). For ease of downstream process and to ensure high production of lactic acid, biomass is recycled back to the fermentor. Unit chosen for this duty is microfilter, which works on microfiltration membrane separation process. On the basis of different sizes between biomass and other dissolved material, biomass will be retained and recycled back to the fermentor. Molecular size of biomass is relatively big, (order of micron[1]) therefore for the microfilter, low-pressure drop membrane process will be sufficient for the process. Even though the whole section is continuous, it is necessary to stop the fermentation every 40 days to maintain aseptic process. Therefore 2 parallel units will be installed and storage or a buffer tank will be necessary. 5.1.2 Shrimp shell pretreatment Main idea of this section is to prepare the raw material for chitin and chitosan production process. Two main considerations are shrimp shells size as it influencing ease of process and product quality and the removal of impurities especially process inhibitors. Therefore two main units are essentially here: size reduction unit and impurity separator. 5.1.2.1 Shrimp Shells Size Reduction There are various size reduction unit available in the market, i.e. grinding, crushing and milling machines. The choice of which equipment to use is based on various criteria, which mainly are hardness of the material, product size class and feed size input. From [2], shrimp shells are considered as fibrous, low abrasion and possibly tough materials. Typical materials in this class include wood and asbestos. For a flow rate of about 1.25 tons/hr the possible equipments are presented below:


CPD 3264 5-2

Table 5.1.1 Size Reduction Equipment Selection Equipment Specification Remarks Ball, pebble, rod and cone mills

Tumbling mills Cylindrical or conical shell, rotating on a horizontal axis, charged with a grinding medium such as balls of steel, flint or porcelain or with steel rods.

Commonly used Simple operation Cheap

Tube mills Similar to ball mills but generally long in comparison with its diameter and uses smaller balls, and produces finer product.

Similar to ball mills

Roller mills Pair of rollers rotating in different speeds in opposite direction.

-

Cage mills Also known as the Stedman disintegrator Cages of one to eight rows, with bars of special alloy steel, revolving in opposite directions

-

Impact breakers Heavy-duty hammer crushers and rotor impact breakers.

-

Vibration mills Two horizontal tubes mounted on springs and given a circular vibration by rotation of a counterweight

Not recommended for continuous operation

Rotary cutters and dicers Use of blades and knife in disintegrating solids - Wet grinding is preferred as in practice it is found that finer size can be achieved rather than by dry grinding. We have chosen ball mill as the unit operation for shrimp shells size reduction considering its ease of operation and low cost. The process will be carried out as wet grinding. 5.1.2.2 Impurity Separator Main ‘hazardous’ impurity in shrimp shells is benzoic acid. It is used on food for preservation. By removing benzoic acid from the shells we can produce a valuable side products: protein hydrolysate and asthaxanthin (-carotene derivative substance). These side products are not saleable with benzoic acid in its compositions. Benzoic acid is leached by ethanol. Ethanol is chosen because of its high solubility and ease of separation. The extraction process is conducted at 25oC, atmospheric pressure. The extractor has to be designed to leach the benzoic acid that is mixed with the shrimp shells. It would be suggested that the vessel mixes the solvent and solids together in a tank and then the spent solids separated from the liquid phase. Few instruments for mixing is possible like a mixer-settler or a rotating disc extractor. However, these unit operations require more than one vessel to accomplish the results. Furthermore the spent solids need to dry when leaving the system and both the mentioned equipments do not have the ability to do so. Hence, the extractor used is based on the concept of the Kennedy extractor. It comprises a nearly horizontal chamber through which in the solids being leached are moved by a slow impeller enclosed in the section. There is opportunity for drainage between the stages when the impeller lifts the solids above the liquid level before dumping them into the solids removal area by the aid of a scraper. The impeller is fitted with a mesh to enable sufficient drainage.(Appendix D.7, Figure D.7.3).


CPD 3264 5-3

Furthermore, ethanol recovery system is considered. By doing this, we can recycle the solvent used and have benzoic acid as saleable side product. Ethanol recovery is done in an single stage evaporator, at 1 atm and 87oC, as an optimization result of ASPEN PLUS 10.2 simulation, with solvent used composed of 75% ethanol and 25% water. During recovery, benzoic acid will precipitate because of the lost of solvent into the vapour phase. Different types of evaporators are available, and below are the available choices: Table 5.1.2 Evaporator choice Evaporator Description Note Forced-circulation Best application for crystalline, corrosive and viscous

products Relative freedom from salting, scaling, and fouling

Chosen

Short-tube vertical Inexpensive, low headroom Unsuitable for crystalline products

Rejected

Long-tube vertical Good heat transfer, low holdup, low cost Unsuitable for crystalline products

Rejected

Horizontal tube Low cost, good heat transfer Unsuitable for salting products

Rejected

The forced-circulation evaporator is chosen because it can handle the benzoic acid slurry with little problem. Since not 100% of the solvent recovered, additional fresh solvent is necessary. Mixing of recovered and fresh solvent is performed in a buffer tank. It is merely a simple storage tanks, essential for regulating the right amount of solutions that needs to be added to the respective tanks for reaction. 5.1.3 Enzymatic deprotenization and demineralization + chitin purification The third section performs the main reaction to ‘extract’ chitin from the shrimp shells and remove other impurities. This operation is conducted in two reactors : the first is conducted enzymatically while the second is conducted chemically. Further separation units will be required to separate the removed impurities from shrimp shells. Therefore this sequence is proposed : Enzymatic reactor – filtration – mixing tank – chemical reactor – filtration. 5.1.3.1 Reactors The first reactor performs enzymatic deproteinization of chitin and demineralization with the help of lactic acid. The reaction is exothermic and the operating temperature is controlled at 25°C to ensure good performance of the enzyme. The second reactor performs chemical demineralization with the help of HCl to complete the demineralization process. Therefore this step is called chitin purification. The reaction is exothermic and is performed adiabatically, to accelerate the reaction rate and for reduction of utility usage. Simulation results shows that maximum temperature achieved are around 40°C, which is still in safe operation conditions. Considering the reaction conditions and the nature of flow, all reactors are of the same design. Choice of reactor type is presented below. Uniformity of the produced chitosan is the main concern of our process. Our aim is to produce uniform products. To produce uniform chitosan, the residence time of each particle


CPD 3264 5-4

in the reactors should be kept in a certain range, because each particle can be assumed as one small batch system.

In terms of the residence time distribution, batch reactor or plug flow reactor have advantages in residence time uniformity. As it is mentioned in chapter 3, batch reactor needs extra operating time and cost for refilling. Extra storages are also required before and after the batch reactor. Plug flow reactor has disadvantages in mixing. In our process, residence time of each reactor is relatively long, from 1 hour to 10 hours (depending on the reactor configurations). Therefore flow rates in a plug flow reactor is extremely slow and it causes less mixing without extra agitation. Moreover chitin and chitosan are hardly soluble in water, hence they exist as particles through the process. The particles may settle at the bottom without good mixing.

There are some options to give good mixing for plug flow reactors (or tube reactor), such as rotating coils, rotating drum reactors, or stirs with baffles. Rotating drum is not favored because of the mechanical difficulties and high utility cost for operation. Due to extremely slow flow rates, baffles are necessary, otherwise back mixing will cause high-distributed products. Baffles and rotating coils are difficult to coexist mechanically. Therefore stirrers with baffles are chosen for our reactors.

Carbon dioxide is formed through demineralization reaction. Therefore it is advisable to position the tube reactor horizontally and install purge for each compartment. Moreover solid particles may have different sedimentation velocities. When a reactor is positioned vertically like a column, different sedimentation velocities may differentiate the residence time of particles and solvent.

Rotating impellers on a horizontal shaft are chosen for the tube reactor. As an option, impellers can be installed vertically for each compartment. However this option needs many motors for each impeller, therefore economically it is not feasible.

5.1.3.2 Filtration

Two filtration units will be installed here. The first one after the enzymatic reactor to separate chitin from the fermentation broth and the second after the second reactor to separate chitin from HCl.

The separation task is quite easy with only separation of solids from liquid. The choice of filter used in this operation is a vacuum rotary drum filter. This is because the rotary drum filter is versatile and simple to use. And importantly, it can be operated continuously. Furthermore rotary drum filters are the most commonly used filters, which makes it cheap to maintain, operate and manufacture.

A rotary drum filter is also suitable for this operation as the solids are the important compounds, and by operation under vacuum, sensitive materials like chitin and chitosan are not exposed to high temperature gradients and harsh conditions. The characteristics of the cake formed are also not of a slurry type, meaning a clarifying filter will not be suitable. Drum filters form a cake layer on the drum and is then scraped by a knife from the drum. The best filter for continuous operation when the scale is small (approximately 1 m3/hr), continuous, and the solids recovered are either washed or untreated, is by using a bottom-fed drum, i.e. a rotary drum filter [3]. With the solids being very fine particles in the suspended liquid solution, the rate of setting would probably be low (<0.1 cm/s) or medium rate ( 0.1-5 cm/s). This would also suggest a rotary drum filter would be suitable for this operation.


CPD 3264 5-5

5.1.3.3 Mixing tank In this section mixing tank plays an impotant role to mix chitin cake with aqueous HCl, forming homogenous-pumpable liquid. It is simple tank, equipped with an impeller. 5.1.4 Chitin deacetylation The last section mainly converts chitin to chitosan. Several steps are added for product finishing. The unit operations sequence is mixing tank – deacetylation reactor – filtration – drying – grinding. 5.1.4.1 Mixing tank Chitin produced in the previous section are in cake form. Usually solid handling is more difficult than liquid. Therefore the cake is mixed with aqueous NaOH, forming homogenous-pumpable liquid which is easier to be heated. The operation is performed in a simple tank, equipped with an impeller. 5.1.4.2 Deacetylation reactor High pressure and temperature is necessary for fast deacetylation process. The reaction will be performed at 121°C, 2 bar. This reaction is catalyzed by alkaline condition stimulated by NaOH. The reactions are performed in the same type of reactor as the previous two reactors with the same consideration.(Chapter 5.1.3.1) 5.1.4.3 Filtration After the reaction is completed, separation between product and the catalyst is necessary. Because it mainly separate between solid and liquid phase, filtration process will be sufficient. Rotary drum filter with vacuum conditions will be applied here, the same consideration as already discussed in 5.1.3.2. To produce high quality product total NaOH removal is necessary and extra washing stage in the unit is applied. Process water is added for this purpose. 5.1.4.4 Drying Final purification step is needed to reduce water content in product, for ease of storing and maintain high product quality (life time). Most of the water content (93%) is already removed in the filtration unit, the remaining will be removed here. There are various drying equipment in the market. The choice of which equipment to use is based on various criteria: heat sensitivity of the product, solid handling characteristics (slurry, paste, solution or solid) solid moisture of equilibrium. Basic consideration is that chitosan is heat sensitive material, above certain temperature its color will darken, and that the feed to the dryer system is filtration cake. Types of dryer suitable for heat sensitive material [4] are drum, tunnel belt screen, spray, flash or fluidized bed dryer. Types of dryer suitable for cake from filtration type of feed [5] are flash, fluidized bed, rotary or tray dryer. Other reference [6] suggests that rotating dryer will be sufficient for both requirements. We have chosen vacuum rotary dryer as the unit operation for its ease of operation (control temperature) and economic of process operation. Operating condition was chosen to be at 0.05 bar, 40°C.


CPD 3264 5-6

5.1.4.5 Grinder One important aspect of product quality is size uniformity. Although we already applied a size reduction unit in the pretreatment section, another grinder will be installed here for ensuring size uniformity. For the same consideration as the first grinder, we have chosen ball mill as the unit operation for its ease of operation and low cost (refer to 5.1.2.1). The operation will be carried out in a dry condition, as the product needs to be dry when sold. 5.1.5 Pump Selection The most commonly used pump in the chemical process industry is the single-stage, horizontal, overhung, centrifugal pump. The pump selection is based on the flow rate and the head required together with other consideration like presence of solid, corrosion etc. The centrifugal pumps are used for normal applications but processes which contain solids or corrosive substances etc, these pumps are not recommended[4,7,8]. As for our case we have both the solids and substances, which are quite corrosive, like HCl and NaOH. Taking into consideration the head required, flow rate, solids and corrosion, the diaphragm pumps turn out to be the choice. Following are the points considered during specification of pumps. 1. The flow rates and head required in our process are quite for most cases and control is not

easy with centrifugal pumps. Also the efficiency of centrifugal pumps goes to very low value for small flows.

2. Most of the streams contain solids. 3. Corrosive substances like HCl and NaOH are present. 4. The head required for most cases are relatively quite small.

5.2 Process Flow Scheme (PFS).

Fully equipped Process Flow Scheme of this project is shown in Figure 5.2.1. The section scheme is also made available in Appendix C.1. A brief explanation will be presented below. Total process is devided into 4 section (plant unit): Section 1: U1000 Lactic Acid Fermentation Section 2: U2000 Shrimp Shells Pretreatment Section 3: U3000 Enzymatic Deproteinization and Demineralization + Chitin Purification Section 4: U4000 Chitin Deacetylation


CPD 3264 5-7

For PFS


CPD 3264 5-8

Every stream and equipment numbers starts with the section number, i.e. stream <101>-<118> in U1000 and E201-E203 in U2000. Main streams are presented in thick line, other streams in normal (full) line, dash and dot line for control connection, and dot line for periodic stream (i.e. innoculum streams). Equipment list with their explanations are available in the bottom part of the figure. Section 1: U1000 Lactic Acid Fermentation Innoculum stream <101> goes directly into Lactic acid fermentor (R101a/b), only used at start up process. Glucose feed stream <102> goes to glucose sterilization unit (E101), then splits up to R101a/b. N-source feed stream <107> goes to N-source sterilization unit (E102), then splits up to R101a/b. Fermentation product <113a/b> goes to biomass recycle microfilter (S101a/b), where biomass is recycled back to R101a/b and the filtrate sent to the lactic acid buffer tank (T101). CO2 produced in the fermentation process <112a/b> is dispersed through a stack. Section 2: U2000 Shrimp Shells Pretreatment Shrimp shells feed <201> are sent to a shrimp shell crusher (A201) for size reduction. The particles are then sent to benzoic acid extractor (S201) to remove benzoic acid. Free benzoic acid shells <204> are sent to the next section. Used solvent <205> is recovered in a ethanol evaporator (C201) after preheated in E201 and E202, producing benzoic acid stream <210> and recycled solvent <213>. Recycled solvent is mixed with fresh solvent <214> in the Ethanol buffer tank (T201), before sent back to S201. Section 3: U3000 Enzymatic Deproteinization and Demineralization + Chitin Purification Lactic acid stream <118> from T101 and pre-treated shrimp shells <204> are sent to the Enzymatic deproteinization-demineralisation reactor (R301 a/b), which are two reactors in series. Gas produced goes to the gas stream <301> while others go to the fermentation broth drum filter (S301) to separate chitin <306> from the fermentation broth <305> which mainly contains protein hydrolysates, lipid, and unused N-source. The chitin cake <306> is mixed with HCl <307> in the HCl chitin mixer (V301) before purified in the Chitin purification reactor (R302). Again gas produced is separated <311> while the rest is sent to the chitin drum filter (S302) to separate the chitin cake <316> from the waste water <315>. Section 4: U4000 Chitin Deacetylation Purified chitin <314> is mixed with the NaOH stream <401> in the NaOH chitin mixer (V401) before preheated in E401 and E402 for deacetylation reaction in the Deacetylation reactor (R401). Chitosan produced here <407> is further cooled in E401 and E403, which then is washed in the Chitosan drum filter (S401). The solid fraction <414> is sent to the dryer (D401) while the waste liquid <412> sent to the waste water treatment facilities. D401 produces water <415> and dry product <416> which will be sent to the chitosan grinder (A401). Chitosan <417>, in uniform size is produced.

5.3 Utilities

As already indicated earlier in Chapter 3, utilities required for the process is steam (low and medium pressure), cooling and chilled water, and electricity. Process simulation and optimisation are done to have all low pressure (LP) steam utilization. Unfortunately, sterilization process has to be conducted at higher pressure and temperature than LP steam specifications for ensuring shortest residence time and maintaining material quality.


CPD 3264 5-9

Process simulation and optimization are also done to enable utilization of cooling water in the whole process. Expect for one process, the enzyme deproteinization and demineralization, to ensure the good performance of enzyme, chilled water is required for controlling the reaction temperature. Utility summary is presented in Table 5.3.1. Detailed utility consumption is presented in Appendix C.2.

Table 5.3.1 Utility Summary Name kg/h kW MP steam 88 LP Steam 184 CW 11883 Chilled water 13021 Electricity 39

5.4 Process Yields

Process yield is presented for components and utilities. The stream yields are explained in Table 5.4.1 and Utilities yields are explained in Table 5.4.2. Utilities summary is present in Figure 5.2.

Table 5.4.1 Process Stream Yields Process Streams

Name Ref. Stream

ton/day t/t product IN OUT IN OUT

Innoculum <101> Glucose <102> 47.9975 20.66 N-source <103> 13.59941 5.85 gas <120> 0.078817 0.03 Shrimp shells <201> 30 12.91 benzoic acid slurry <209> 0.59769 0.26 ethanol <212> 0.357 0.15 gas <302> 1.511213 0.65 fermentation broth <304> 78.91466 33.97 HCl <305> 45.03 19.38 gas <307> 0.12226 0.05 Waste water <310> 45.71482 19.68 NaOH <401> 67.31 28.97 water <408> 10.38 4.47 Waste water <410> 82.93494 35.70 wet gas <412> 2.476381 1.07 Product <413> 2.323126 1.00 Total 214.67 214.67 92.41 92.41


CPD 3264 5-10

ber : CPD3264 e : Dec-01

Chitin Chitosan Production from Shrimp Shells

Shrimp shells

30.0 t/d; (12.91 t/t)

Innoculum

-

Glucose

48.0 t/d; (20.66 t/t)

N-source

15.6 t/d; (5.85 t/t)

Ethanol

0.4 t/d; (0.15 t/t)

HCl

45.0 t/d; (19.38 t/t)

NaOH

67.3 t/d; (28.97 t/t)

water

10.4 t/d; (4.47 t/t)

Chitosan

2.3 t/d; (1 t/t)

Gas

1.7 t/d; (0.73 t/t)

Wet gas

2.5 t/d; (1.06 t/t)

Waste water

128.6 t/d;(55.58 t/t)

Benzoic acid slurry

0.6 t/d; (0.26 t/t)

Fermentation broth

78.9 t/d; (33.97 t/t)

MP steam

2.10 t/d; (0.90 t/t)

LP steam

4.42 t/d; (1.90 t/t)

Cooling water

473.1 t/d;(203.67t/t)

Chilled water

312.50t/d;(134.52t/t)

Electricity

39kWd/d;(16.58kW/t)


CPD 3264 5-11

Table 5.4.2 Utilities Yields

Utilities

kg/h kW ton/d kWd/d t/t product kWh/t

product MP steam 88 2 0.91 LP Steam 184 4 1.90 Cooling Wwater 11883 285 122.76 Chilled water 13021 313 134.52 Electricity 39 39 16.58


CPD 3264 5-12

1 www.membranegroup.kt.dtu.dk 2 Table 10.13 in Coulson & Richardson Vol 6 3rd Edition, p 464 3 Robert H. Perry, “Perry’s Chemical Engineers’ Handbook, 7th Edition”, p 18-105, Table 18-11 4 Coulson vol. 6 5 Mujumdar & Menon 6 C.M. van’t Land 7 www.americanlewa.com 8 www.edsonpumps.com


CPD 3264 6-1

Chapter 6 : Process Control A process requires a number of events to take place in a particular sequence in the most efficient and economical method. These events take place efficiently only if the results of a preceding event are always predictable and repetitive, thereby requiring the least effort to run the subsequent step in an optimum way. In an ideal process, all inputs are constant in quality (e.g., composition, temperature and pressure) and in quantity (flow rate, for example). Every process step has fixed and constant parameters, such as constant heating rates, constant flow-splitting characteristics and so on. The process runs smoothly and produces even quality and quantity products. In reality, processes are never ideal and do not run in a steady state for any appreciable length of time. There are all sorts of upsets in the process operating conditions – feed stream compositions or flow rates, climatic conditions, and so on – that subject it to dynamic variations, which cause the final product to fluctuate from its desired properties more or less widely. Hence, process control is introduced to the system for efficient control of quality and quantity as much as possible in a dynamic situation. Process control is also used as a tool to ensure safe operation of the system, which inherently would be the most important factor in determining the control system of a unit operation. In this section, process control will be discuss based on the various sections in the PFS diagram (Figure 5.2.1) in Chapter 5. The sections are: Section 1 : Lactic acid fermentation Section 2 : Shrimp shell pretreatment Section 3 : Enzymatic deprotenization and demineralization + chitin purification Section 4 : Chitin deacetylation 6.1 Section 1: Lactic acid fermentation 6.1.1 R101 a/b Lactic acid Fermentor The fermentor is controlled based on the following:

a. The outflow of the reactor is controlled based on a ratio controller (RC) for the two input streams of glucose and N-source. The input streams are installed with flow controllers (FC). This ensures the reaction takes place in a controlled flow. In addition to this control, a level controller (LC) is also installed. This controller acts as the master controller over RC (Slave controller). LC will overwrite the orders of RC when the level of the tank reaches too low or too high. Safety then becomes a priority.

b. The flow rate of cooling water is controlled by a temperature controller (TC) measuring the reactor temperature. This keeps the exothermic reaction under control and the production of lactic acid within range.

c. The reactor is purged with N2 gas to ensure an anaerobic condition in the vessel. A pressure controller (PC) is installed to ensure that the pressure is always kept constant at a positive pressure by regulating the flow of nitrogen into the reactor.

d. A density indicator (I) is installed to measure the density of the mixture because of the growth of biomass. This is to check if the cells are still growing or dying because of unfavourable conditions.


CPD 3264 6-2

e. Since in the reaction strong acids are produced, and the reaction needs to be controlled at pH 5.5, a pH controller (pHC) is incorporated to regulate the pH by adding buffer alkaline solutions.

6.1.2 S101 a/b Microfilter The microfilter separates solids from liquids by the driving force of pressure difference. Hence, the higher the inlet pressure the quicker the microfilter would filter. However, control of the microfilter may not be done as this would conflict with the controls of the fermentor. To regulate control, a pressure controller (PC) needs to be installed on stream 114 a/b to control the pump power of P105 a/b. However, on line 113 a/b, the flow is already controlled by the controls of R101 a/b. Since the fermentor is the more important equipment, only a pressure indicator (PI) is installed for safety purposes. 6.1.3 T101 Lactic acid buffer tank This tank is an intermediate tank that is required for lactic acid storage before it can be introduced in to R301. Hence, a level controller (LC) is installed for safety measurements. This controller is the master controller in the cascade control of flow stream 118. When the level of the tank is too high or low, it will set a new set point on the FC on stream 118, which will eventually cause the RC to regulate the speed of conveyer X301 and the flow rate of 118. 6.2. Section 2 : Shrimp shell pretreatment 6.2.1 C201 Ethanol Evaporator The controls of the evaporator are:

a. The temperature of the vessel controls (TC) the steam flow rate. Temperature of the vessel is directly related to the steam flow rate, and hence gives fast and efficient response.

b. The pressure of the tank is controlled by the vapour flow rate by a valve. The pressure of the vessel is mainly contributed by the evaporate produced as the change in phase causes an increase in volume, and might cause a built up in pressure if the vapour flow rate is not regulated.

c. A level control is installed as well to ensure that the level of liquid does not go below the heat exchanger. If the level drops below the heat exchanger, and the heating is exposed to the vapour phase, a hot spot may develop as heat transfer is less efficient in air. Therefore it is essential to maintain the level of the vessel by regulating the flow of stream 209.

6.2.2. T201 Ethanol Buffer tank The primary reason for control here is for safety. A level controller (LC) is installed to maintain the level of the vessel, especially not to let the tank overflow as ethanol is a highly flammable material. The level of the tank is controlled by regulating the incoming fresh ethanol feed (stream 215). The fresh ethanol feed is also controlled by the amount of recycled feed into T201. If the recycle increases, the controller will reduce the amount of fresh ethanol needed. Hence, the flow controller on stream 213 acts as the slave controller while the LC is the master controller in this cascade control.


CPD 3264 6-3

6.2.3 S201 Benzoic acid extractor This vessel on itself requires no specific control. According to Chapter 5.1, equipment selection, the level of the tank is self regulating. Solvent flows into the vessel and leaves because of height difference (Appendix D.7, Figure D.7.3). The only required controls are the inflow of shrimp shells and the amount of ethanol fed into the vessel. A ratio controller can do this by taking the flow measurements of the incoming ethanol feed (stream 216) and the mass and conveyer speed (FC) of X202. By setting a set point for the ratio between these two streams, stream 216 is regulated by a valve. 6.3 Section 3 : Enzymatic deprotenization and demineralization + chitin purification 6.3.1 R301 a/b Enzymatic deproteinization and demineralization reactors The flow into the reactor is controlled mainly by a ratio controller. The ratio controller receives inputs from the flow rate of line 118 (lactic acid) and 204 (shrimp shells). Again, with a ratio set, stream 118 is regulated by a valve. However, this regulating mechanism is overwritten when tank T101 needs level correction. The LC (master controller) of T101 then resets the set point of FC (slave controller), and hence causes the valve of 118 to either close or open more. The change of stream 118 flow rate will then change the speed of X301 conveyer, i.e. to keep the same ratio needed for the feed into R301 a/b. The reaction in R301 a/b is exothermic. Hence, cooling water is introduced to keep the rate of reaction constant. The temperature of the reactor plays the main role in controlling the rate of reaction. Hence, the temperature is controlled by regulating the amount of cooling water required for the reactor. 6.3.2 S301 and S302 Vacuum Drum Filters The drum works on the driving force of vacuum produced by a vacuum pump. A pressure controller (PC) is installed on the vacuum line, which will control the power of the vacuum pump (not on PFS diagram). A flow indicator is installed for safety and maintenance reasons. The filtrate flow can indicate if there is a crack in the filter or if the filter is clogged. The feed line is fitted with a pressure indicator for safety purposes. This allows the user to know the pressure difference between the vacuum line and the feed. If the pressure of the feed changes too much, the set point for the pressure controller on the filtrate line can be manipulated. 6.3.3 R302 Chitin Purification reactor Unlike R301 a/b, this reactor is an adiabatic reactor. There are no utilities for this vessel to keep the temperature under control. The tank is allowed to freely increase in temperature because of the heat produced during reaction. However, there is a risk of runaway if the temperature of the vessel is not regulated. The only way to regulate the temperature (TC) of the tank is to control the flow rate of the inlet feed. Reducing the total mass flow will reduce the amount of reaction and hence, reduce heat produced. The inlet to the reactor is also regulated by a Ratio controller (RC). This RC is needed to maintain the right ratio between the chitin fraction and HCl. The amount of HCl is controlled in this case to keep the chitin flow continuous and undisturbed.


CPD 3264 6-4

Prior to the reactor is a mixing tank V301. This tank is fitted with a level indicator for safety purposes. If the level is too high or low, it will sound an alarm, and hence, manual manipulation can be done. 6.4 Section 4 : Chitin deacetylation 6.4.1 R401 Deacetylation reactor As with R301 a/b, the reaction is controlled by a temperature controller (TC) by regulating the cooling water utility. The inlet feed as with R302, is controlled by a ratio controller (RC). NaOH flow rate is regulated by a valve based on the set point of the RC, which receives information of flowrate of stream 402 and conveyer X401 speed. The mixing tank V401 is also fitted with a level indicator (LI) for safety purposes. 6.4.2 S401 Vacuum drum filter Refer 6.3.2 for details. 6.4.3 D401 Product dryer Finally, the product dryer, which works under vacuum, the pressure of the vessel is controlled by a pressure controller (PC) which regulates the vacuum pump. On the other hand, the temperature of the vessel is controlled by a temperature controller (TC), which controls the flow of steam into the vessel. By this arrangement, the product quality can be maintained, and the system kept under control.


CPD 3264 7-1

Chapter 7 : Mass and Heat Balances This chapter presents heat and energy balance simulation result. Only brief summary will be presented here, while lengthy table (stream summary in Appendix C.3) and detailed calculation method will be presented in Appendix (Appendix D.1 for Aspen simulation and D.2 for fermentation simulation). 7.1 Practical Aspects Simulation results of balance mass and energy calculation, are presented in Table 7.1 and Table 7.2. Difficulty arises as two different simulators, Aspen and SuperPro, plus manual calculation were used. This is due to the incapability of Aspen for handling fermentation system. Different data and standards used between simulators and lack of accurate data, especially for biological systems may result in imbalance system. Special attention is paid for heat balance as the tendency of imbalance is higher. However, the problem was successfully overcome by parallel iterative simulation and optimisation, although very little imbalance in heat balance (0.4%) is still unavoidable (Table 7.3). 7.2 Balance for Total Streams Balance for total stream to check the ‘zero difference’ consistency across each unit is presented in Table 7.1. The table consists mainly of 4 part: - input of total plant : where stream or heat enters the plant; stream across battery limit - input of specific equipment : where stream or heat are entering equipment - output of specific equipment : where stream or heat are leaving the plant, stream across

battery limit - output of total plant : where stream or heat are leaving equipment For each stream total mass and heat are indicated. Units chosen here are tonnes/day and kW as they are more representable and give more insight about the stream. Positive heat in to the plant means heating is required while positive heat out of the plant mean cooling is required. In the last part of Table 7.1 we find that total mass and heat across the plant is balanced. 7.3 Balance for Stream Components Balance for stream component is presented in Table 7.2. As reactions are occurred in the process, difference between input and output for every component is not zero. However the difference between total input stream and total output stream remains zero. For consistency of heat balance, the difference between stream enthalpy entering and leaving the plant should be equal to the difference between heating and cooling requirements. Heat balance check is presented in Table 7.3.


CPD 3264 7-2

Table 7.1 Total Stream Mass and Heat Balance IN OUT

Plant EQUIPMENT EQUIPM. EQUIPMENT Plant

Mass Heat Mass Heat Stream IDENTIF. Stream Mass Heat Mass Heattonnes/day kW tonnes/day kW Nr. Nr. tonnes/day kW tonnes/day kW

47.997 -7937 47.997 -7937 <102> P101 <103> 47.997 -7937 0.000 0 47.997 -7937 Total 47.997 -7937 0.000 0

47.997 -7937 <103> <104> 47.997 -7900 37 37 E101

0.000 0 47.997 -7900 Total 47.997 -7900 0.000 0

47.997 -7900 <104> P103 <105> 47.997 -7900 0.000 0 47.997 -7900 Total 47.997 -7900 0.000 0

13.599 -2401 13.599 -2401 <107> P102 <108> 13.599 -2401 0.000 0 13.599 -2401 Total 13.599 -2401 0.000 0

13.599 -2401 <108> <109> 13.599 -2389 12 12 E102

0.000 0 13.599 -2389 Total 13.599 -2389 0.000 0

13.599 -2389 <109> P104 <110> 13.599 -2389 0.000 0 13.599 -2389 Total 13.599 -2389 0.000 0

0.000 0 0.000 0 <101> <112a/b> 0.079 -8 0.079 -8 47.997 -7900 <106a/b> <113a/b> 85.256 -13958 13.599 -2389 <111a/b> 23.738 -3601 <115a/b> 0 R101a/b 77 77

0.000 0 85.334 -13889 Total 85.334 -13889 0.000 0

0 85.256 -13958 <113a/b> P105a/b <114a/b> 85.256 -13958 0.000 0 85.256 -13958 Total 85.256 -13958 0.000 0

85.256 -13958 <114a/b> <115a/b> 23.738 -3601 S101a/b <116a/b> 61.518 -10357

0.000 0 85.256 -13958 Total 85.256 -13958 0.000 0

61.518 -10357 <116a/b> <117> 61.518 -10396 T101 39 39

0.000 0 61.518 -10357 Total 61.518 -10357 0.000 0

0 61.518 -10396 <117> P106 <118> 61.518 -10396 0.000 0 61.518 -10396 Total 61.518 -10396 0.000 0

30.000 -3886 30.000 -3886 <201> A201 <202> 30.000 -3886 0.000 0 30.000 -3886 Total 30.000 -3886 0.000 0

30.000 -3886 <202> <204> 29.759 -3879 1.354 -132 <203> S201 <205> 1.595 -138

0.000 1 31.354 -4018 Total 31.354 -4017 0.000 0

1.595 -138 <205> P201 <206> 1.595 -138 0.000 0 1.595 -138 Total 1.595 -138 0.000 0

1.595 -138 <206> <207> 1.595 -135 0.997 -79 <211> E202 <212> 0.997 -82

0.000 0 2.592 -217 Total 2.592 -217 0.000 0


CPD 3264 7-3

Table 7.1 continued IN OUT


Mass Heat Mass Heat Stream IDENTIF. Stream Mass Heat Mass Heat tonnes/day kW tonnes/day kW Nr. Nr. tonnes/day kW tonnes/day kW

1.595 -135 <207> <208> 1.595 -135 0 0 E201

0.000 0 1.595 -135 Total 1.595 -135 0.000 0

1.595 -135 <208> <209> 0.598 -41 <211> 0.997 -79 14 14 C201

0.000 0 1.595 -121 Total 1.595 -121 0.000 0

0.598 -41 <209> P204 <210> 0.598 -41 0.598 -410.000 0 0.598 -41 Total 0.598 -41 0.000 0

0.997 -82 <212> <213> 0.997 -95 0 E203 12 12

0.000 0 0.997 -82 Total 0.997 -82 0.000 0

0.357 -37 0.357 -37 <214> P202 <215> 0.357 -37 0.000 0 0.357 -37 Total 0.357 -37 0.000 0

0.997 -95 <213> <216> 1.354 -132 0.357 -37 <215> T201

0.000 0 1.354 -132 Total 1.354 -132 0.000 0

1.354 -132 <216> P203 <203> 1.354 -132 0.000 0 1.354 -132 Total 1.354 -132 0.000 0

61.518 -10396 <118> <301> 1.511 -156 1.511 -156 29.759 -3879 <204> <302> 89.766 -14232 0 R301a/b 114 114

0.000 0 91.277 -14275 Total 91.277 -14275 0.000 0

89.766 -14232 <302> P301 <303> 89.766 -14232 0.000 0 89.766 -14232 Total 89.766 -14232 0.000 0

89.766 -14232 <303> <304> 78.915 -12911 S301 <306> 10.852 -1321

0.000 0 89.766 -14232 Total 89.766 -14232 0.000 0

78.915 -12911 <304> P303 <305> 78.915 -12911 78.915 -129110.000 0 78.915 -12911 Total 78.915 -12911 0.000 0

45.030 -8141 45.030 -8141 <307> P302 <308> 45.030 -8141 0.000 0 45.030 -8141 Total 45.030 -8141 0.000 0

10.852 -1321 <306> <310> 55.882 -9462 45.030 -8141 <308> V301

0.000 0 55.882 -9462 Total 55.882 -9462 0.000 0

55.882 -9462 <309> P304 <310> 55.882 -9462 0.000 0 55.882 -9462 Total 55.882 -9462 0.000 0

55.882 -9462 <310> <311> 0.122 -13 0.122 -13 0 R302 <312> 55.759 -9450

0.000 0 55.882 -9462 Total 55.882 -9462 0.000 1

55.759 -9450 <312> P305 <313> 55.759 -9450 0.000 0 55.759 -9450 Total 55.759 -9450 0.000 0


CPD 3264 7-4

Table 7.1 continued IN OUT


Mass Heat Mass Heat Stream IDENTIF. Stream Mass Heat Mass Heat tonnes/day kW tonnes/day kW Nr. Nr. tonnes/day kW tonnes/day kW

55.759 -9450 <313> <316> 10.044 -1260 S302 <314> 45.715 -8189

0.000 0 55.759 -9450 Total 55.759 -9450 0.000 0

45.715 -8189 <314> P306 <315> 45.715 -8189 45.715 -81890.000 0 45.715 -8189 Total 45.715 -8189 0.000 0

67.310 -9255 67.310 -9255 <401> P401 <402> 67.310 -9255 0.000 0 67.310 -9255 Total 67.310 -9255 0.000 0

10.044 -1260 <314> <403> 77.354 -10515 67.310 -9255 <402> V401

0.000 0 77.354 -10515 Total 77.354 -10515 0.000 0

77.354 -10515 <403> P402 <404> 77.354 -10515 0.000 0 77.354 -10515 Total 77.354 -10515 0.000 0

77.354 -10515 <404> <405> 77.354 -10384 77.354 -10374 <408> E401 <409> 77.354 -10506

0.000 0 154.709 -20889 Total 154.709 -20889 0.000 0

77.354 -10384 <405> <406> 77.354 -10358 25 25 E402

0.000 0 77.354 -10358 Total 77.354 -10358 0.000 0

77.354 -10358 <406> <407> 77.354 -10374 0 R401 15 15

0.000 0 77.354 -10358 Total 77.354 -10358 0.000 0

77.354 -10374 <407> P403 <408> 77.354 -10374 0.000 0 77.354 -10374 Total 77.354 -10374 0.000 0

77.354 -10506 <409> <410> 77.354 -10521 E403 15 15

0.000 0 77.354 -10506 Total 77.354 -10506 0.000 0

77.354 -10521 <410> <414> 4.800 -641 10.380 -1905 10.380 -1905 <411> S401 <412> 82.935 -11785 0.000 0 87.734 -12426 Total 87.734 -12426 0.000 0

82.935 -11785 <412> P404 <413> 82.935 -11785 82.935 -117850.000 0 82.935 -11785 Total 82.935 -11785 0.000 0

4.800 -641 <414> <415> 2.476 -384 2.476 -384 <416> 2.323 -186 71 71 D401

0.000 0 4.800 -570 Total 4.800 -570 0.000 0

2.323 -186 <416> A401 <417> 2.323 -186 2.323 -1860.000 0 2.323 -186 Total 2.323 -186 0.000 0

214.674 -33401 Total 214.674 -33401

OUT - IN : 0.000 0

Project ID Number : CPD3264 Completion Date : Dec 2001


CPD 3264 7-5

Table 7.2 Overall Component Mass Balance & Stream Heat balance

IN OUT OUT-IN

STREAM Nr. :

<101>,<102>,<107> <201>,<214>

<307> <401>, <411>

<112a>,<112b> <210>

<301>,<305>,<311>,<315><413>,<415>,<417>

Name : Total Plant Total Plant Total Plant

COMP MW tonnes/day kmol/day tonnes/day kmol/day tonnes/day kmol/day

Acetic Acid 60.052 0.000 0.000 0.464 0.008 0.464 0.008

Ammonium sulphate 132.16 0.526 0.004 0.053 0.000 -0.473 -0.004

Benzoic Acid 122.12 0.300 0.002 0.300 0.002 0.000 0.000

Calcium carbonate 100.087 0.000 0.000 0.024 0.000 0.024 0.000

Calcium Cloride 110.986 3.978 0.036 0.417 0.004 -3.561 -0.032

Calcium Lactate 218.221 0.000 0.000 7.801 0.036 7.801 0.036

Carbon dioxyde 44.01 0.000 0.000 1.818 0.041 1.818 0.041

Chitin 203.194 1.825 0.009 0.257 0.001 -1.569 -0.008

Chitosan 161.157 0.608 0.004 1.852 0.011 1.244 0.008

Ethanol 46.07 0.247 0.005 0.247 0.005 0.000 0.000

Glucose 180.16 9.011 0.050 0.241 0.001 -8.770 -0.049

Hydrocloric Acid 36.461 0.820 0.022 0.523 0.014 -0.297 -0.008

Lactic Acid 90.079 0.000 0.000 1.201 0.013 1.201 0.013

Lipid 284.48 0.351 0.001 0.351 0.001 0.000 0.000

Lactobacillus sp. 24.6 0.000 0.000 0.881 0.036 0.881 0.036

Nitrogen 14.01 0.000 0.000 0.000 0.000 0.000 0.000

Oxygen 32 0.000 0.000 0.000 0.000 0.000 0.000

Protein 123.54 4.703 0.038 4.703 0.038 0.000 0.000

Sodium Hydroxide 39.997 30.290 0.757 30.265 0.757 -0.025 -0.001

Sodium Cloride 58.44 0.000 0.000 0.037 0.001 0.037 0.001

Sulphuric Acid 98.0734 0.000 0.000 0.351 0.004 0.351 0.004

Water 18.02 162.014 8.991 162.888 9.039 0.874 0.049

Total 214.674 9.920 214.674 10.014 0.000 0.094

Enthalpy [kW] -33562.1 -33674.09 -111.9893

Project ID Number : CPD3264 Completion Date : Dec 2001

Table 7.3 Heat Balance Check input output difference

Utilities [kWatt] 160 272 -112stream enthalpy [kWatt] -33562 -33674 112

total 0

-0.4%


CPD 3264 8-1

Chapter 8 : Process and Equipment Design From the block diagram (Fig 3.2.2) in Chapter 3 and the Process Flow Scheme (Figure 5.2.1.) in Chapter 5, each equipment within the battery limits are further designed for their specifications, i.e. the size, utility consumption and internal specifications. Each unit operation is designed based on the design criteria, and hence certain assumptions for required performance are fixed, e.g. split ratios, extent of reaction, pressure drop, efficiency, utility temperatures, etc. For ease of design, ASPEN PLUS simulation is used for primary sizing of all the unit operations except the equipments in the lactic acid fermentation section. ASPEN PLUS is further used for optimization of reactors of R301, R302 and R401. ASPEN PLUS also initially designs the heat exchangers and evaporator C201 for heat duties. As for fermentor R101 a/b, the design is done on MATLAB and a spreadsheet (Microsoft Excel). This unit involves various biological components and criterias of wash out, dilution factor, product and substrate specific rates and growth rates which are unavailable in ASPEN PLUS. A check is then done on SUPERPRO DESIGNER for the fermentor. After the initial sizing of each equipment, the data is transferred on a spreadsheet for detailed specifications. 8.1 Integration by Process Simulation ASPEN PLUS is used as the primary simulation tool. However, certain problems were encountered with this tool, e.g. availability of physical and chemical properties and the existence of solids in the system. 8.1.1 Components settings Group 1) Components, the properties of which exist in ASPEN databanks Following components, which are listed below, are in ASPEN databanks.

Acetic acid, Ammonium sulfate, Benzoic acid, Calcium chloride,

Calcium carbonate, Calcium lactate, Carbon dioxide, Ethanol, Water,

Sulfuric acid, Hydrogen chloride, Lactic acid, Nitrogen, Sodium hydroxide,

Oxygen

However, some data, such as heat of generation, are missing for calcium carbonate and calcium lactate, therefore some properties are estimated by general functional groups. In molecular structure general sheet, the molecular connectivity for one pair of atoms is specified through indicating atom type and type of bond that connects the two atoms. Unique number is assigned to each atom except hydrogen atoms. Missing data are estimated by Aspen, which uses this information to build the required functional groups for all estimation methods used in the run. Water, which is bounded to shrimp shell, is expressed as ‘H2O- Bound’, and it is treated as solid. Water, which exists as liquid and forms aqueous phase, is expressed as ‘H2O-Free’.


CPD 3264 8-2

Group 2) Components, which do not have specific structure Carbohydrates, protein, and lipids are generic names of the components, and they do not have exact structure. However, they can be represented by some specific components, which have data in ASPEN. Therefore the properties of certain components are estimated by substituting components as follows.

Glucose (Carbohydrates): Dextrose (C6H12O6) Protein: Leucine (C6H13NO2) Lipids: Stearic Acid (C18H36O2)

While some data are missing for dextrose and leucine, general function groups are applied to estimate these missing values. In our process, solid protein in the shrimp shell becomes soluble through the reaction, which is deproteinization. Solid protein and soluble protein are defined as ‘Protein (S)’, and ‘Protein (L)’, in which ‘S’ and ‘L’ represent solid phase and liquid phase respectively. Group 3) Rest of the components Following components’ properties are not in ASPEN databanks.

Chitin (C8H13NO5) Chitosan (C6H11NO4)

Their properties are estimated through general function group, which is mentioned above. Moreover these components are solids and Joback and vanKrev functional groups are applied to get all the properties we need. The properties are shown in Table 4.1 Chapter 4 and Appendix B. In our designing process, some components exist as solid, e.g. chitin, chitosan, calcium carbonate, benzoic acid, insoluble protein, and glucose. However, most of the units are treated (separated) without phase equilibriums or partition coefficients, which strongly depends on the phase conditions of components. The reaction kinetics is also overall kinetics, which involves the solidness of the material. In general, properties as solid, such as porosity and particle size, effect strongly on reaction rate. However the kinetics was interpreted from the articles, the experiments of which had been done through the reaction in solid phase. Moreover, we could not get further kinetics information that might help us to consider solidness. By using this kinetics, it is not necessary to consider further solidness, such as porosity, particle size, in ASPEN simulation. Therefore in main simulation, we treat all the components as liquid, also because ASPEN shows difficulty to estimate solid components’ parameters. However solidness of the components is necessary to simulate the filter, which is solid and liquid separation. Hence, sub simulations are took place for the filters and the results are interfered to the mail simulation. As mentioned before, we experienced problems with Aspen simulation when chitin and chitosan were specified as solids components. But for simulating filter it is necessary to specify chitin and chitosan as solid components. To overcome this problem, filters were simulated separately using polymer plus in Aspen. As chitin and chitosan are basically natural polymers, there were specified as generic polymers providing the functional groups of chitin and chitosan monomers utilizing Vankrev model. The degree of polymerization was set as 100. Aspen generates the polymer and calculate the specified properties. In this way filters were simulated for chitin and chitosan polymers and results were compared with designed filters. The results fits well with


CPD 3264 8-3

calculated values. This simulation was not proceeded for other units due to the fact that Aspen assumes the molecular weight of generic polymers as 1. 8.1.2 Thermodynamics Model In our process, there are polar and non-polar components. Non Random Two Liquid method (NRTL) can handle any combination of polar and non-polar compounds, up to very strong non-ideality. It is recommended for highly non-ideal chemical systems, and can be used for vapor-liquid equilibrium (VLE) and liquid-liquid equilibrium (LLE) applications. The NRTL model can describe VLE and LLE of strongly non-ideal solutions. The model requires binary parameters. Many binary parameters for VLE and LLE, from literature and from regression of experimental data, are included in the Aspen Plus databanks. The only restriction of this method is that parameters should be fitted in the temperature, pressure, and composition range of operation, and no component should be close to its critical temperature. Please refer chapter 4 for further information about thermodynamics 8.1.3. Reactions All the reactions are expressed in power law in ASPEN. Enzymatic demineralization, deproteinization

3 2 22CaCO LacticAcid CalciumLactate CO H OFree (EnzDM)

( ) ( )Protein S Protein L (EnzDP) Chemical demineralization 3 2 2 22CaCO HCl CaCl CO H OFree (ChemDM) Chemical deacetylation

2Chitin H OFree Chitosan AceticAcid (ChemDA) Chemical deproteinization first step

( ) ( )Protein S Protein L (ChemDP1) Chemical deproteinization second step

( ) ( )Protein S Protein L (ChemDP2)

Neutralization

2HCl NaOH NaOH H O (Neutral)

Table 8.1.1 Summary of reactions in ASPEN k [1/s] E [kJ/kmol] Exponent

EnzDM 0.0001268 0 CaCO3: 0.4567 Lactic Acid: 0.584 EnzDP 0.007 0 Protein(S): 4.219 EnzDG 0.007 0 Glucose(S): 4.219

ChemDM 0.001655 11800 CaCO3: 1 ChemDA 4100000 71774 Chitin: 1 ChemDP1 7483 35800 Protein(S): 1 ChemDP2 0.719861 24760 Protein(S): 1 Neutral 0.05 0 HCl: 1


CPD 3264 8-4

The summary of reactions in ASPEN is described in Table 8.1.1. k [1/s] is rate constant and E [kJ/kmol] is activation energy. Pseudo first order reactions are estimated for chemical reactions. Please refer to Appendix A for further kinetics analysis. 8.1.4 Feed The feed input are given on Table D.1.1, Appendix D.1. 8.1.5 Setting of units Reactors Enzymatic deproteinization and demineralization (R301) In this reactor, enzymatic reactions (EnzDM, EnzDP) take place. For chitin deproteinization and demineralization, 5 ‘RCSTR’s are used in ASPEN simulation. Please refer the section “Test simulation for reactors.” It is rigorous continuous stirred tank reactor with rate controlled reactions based on know kinetics. In these reactors, temperature is set as 25 ºC and pressure is set as 1 atm. Valid phase of reactor is ‘Vapor-Liquid’, because carbon dioxide is generated through the demineralization. ‘Design Spec’ is used to calculate volume of the last reactors in series. It is a function in ASPEN that is used to set a process variable, which is normally calculated during the simulation. To use this function, it is necessary to specify which model variables must be fixed, what values they must be fixed at, and which model input variables can be manipulated. Those model variables are specified with target values and tolerances, and are adjusted by changing the manipulated variable. Specification of this reactor was 90 % of deproteinization, and manipulated variable was volume of the reactor, which placed last in series. By trial and error, changed volume of the other reactors to get equal reactor volume including last reactor. As a result, total working reactor volume is calculated as 14.21 m3. Please refer to Table D.1.2, Appendix D.1 for design specification and Table D.1.3, Appendix D.1 for simulated results. Chitin purification (R302) In this reactor, chemical demineralization (ChemDM) takes place. As same with the chitin deproteinization and demineralization reactor, 5 ‘RCSTR’ are used for chitin purification in ASPEN simulation. This unit is operated adiabatically. Pressure is set 1 atm and heat duty of the reactor set to be 0. Valid phase is vapor- liquid. Chemical reaction with hydrogen chloride, ChemDM, takes place in these reactors. Using ‘Design Spec’ function and total reactor volume is calculated as 1.55 m3 with 15 % safety factor for design. Temperature increases from 25 ºC to 40 ºC, from first reactor to last reactor in series, due to the heat of reaction. Please refer to Table D.1.4, Appendix D.1. Chitin Deacetylation (R401) In this reactor, chemical deacetylation (ChemDA) and chemical deproteinization (ChemDP1 and ChemDP2) take places. Moreover, neutralization (Neutral) with hydrochloric acid and sodium hydroxide takes place. As same with the other two reactors mentioned above, 5 ‘RCSTR’ are used to represent tube reactor with baffles. Chemical deacetylation occur in all ‘RCSTR’s. While chemical deproteinization has two steps, in the first reactor the first step of deproteinization (ChemDP1) takes place until it is reached 95 % of deproteinization based on inlet concentration


CPD 3264 8-5

of protein (S). ‘Design Spec’ is used for the first reactor to determine volume to specify 95 % of deproteinization. From the second ‘RCSTR’ to last ‘RCSTR’ in series, second step of deproteinization (ChemDP2) takes place. Reactor volume is determined by degree of deacetylation and it is specified by ‘Design Spec’ to meet 90 % of deacetylation based on the total sum of chitin and chitosan. Neutralization (Neutral) is applied only first reactor, because this reaction is so fast. Please refer to Table D.1.5, Appendix D.1. Test simulation for reactors As it is described in Chapter 5, tube reactors with baffles are chosen for all the reactors. One tube reactor is divided into 16 compartments by 15 baffles, and each section has 3 impellers to ensure good mixing. It is proper to estimate them as CSTRs in series. In ASPEN simulation all the reactors work as ideal reactors, therefore the residence time distribution is not taking into account. Relationships between reactor working volume and number of CSTRs in series for first order reactions are shown in Figure 8.1.1. Working volume is normalized based on one CSTR. According to the Figure 8.1.1, total reactor required volume decrease, when increase number of CSTRs in series. When a reactor is designed, it is better to have extra volume, such as 15-20 % of the working reactor volume for safety factor of design. The reactor working volume of 5 CSTRs in series is 15-20 % larger than that of 16 CSTRs in series. To simplify the simulation, we used 5 CSTRs in series instead of using 16 CSTRs in series, in main simulation. Then, the total working volume for 5 CSTRs in series, which is calculated from the simulation, is taken as the design volume of reactor with 15 % of safety factor for design.

Figure 8.1.1 Reactor working volume and number of CSTRs

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 2 4 6 8 10 12 14 16 18 20Number of CSTRs

Rea

ctor

Vol

ume

(Bas

ed o

n 1

CS

TR

)[-]

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 2 4 6 8 10 12 14 16 18 20Number of CSTRs

Rea

ctor

Vol

ume

(Bas

ed o

n 1

CS

TR

)[-]


CPD 3264 8-6

Separators (Extractor, Distillation, Filter, Dryer) Benzoic Acid extractor (S201) In this extractor, 1.00 tonne/day of ethanol and 0.33 tonne/day of water, which are 40 % excess amount of the equilibrium, are used to extract benzoic acid from shrimp shell. As our design assumption, 5 % of extract (ethanol and water) is lost through operation and flow with shrimp shell solid particles. As explained in the detailed calculation in chapter 5, 99 % of benzoic acid is assumed to be extracted from the shrimp shell due to the high solubility of benzoic acid to ethanol. In ASPEN, we use “Sep”, which is component separation that separates components based on specified flows split fractions. Please refer to Table D.1.6, in Appendix D.1 for design specification. Ethanol Evaporator (C201) Through this flash operation, benzoic acid precipitates following evaporation of ethanol and water. Therefore slurry flow, which consists of half benzoic acid and half solvent (ethanol and water), is formed in the bottom of this flash distillation column. To make slurry flow from bottom, in total 25 percent of extract (water and ethanol) stays as liquid and form slurry with benzoic acid. In ASPEN, “Flash2” is used, which is two out-let flash that models flash drums, evaporators, and so forth using rigorous vapor-liquid equilibrium. Pressure is set as 1 atm and vapor fraction is set as 0.70 by trial and error simulation through ASPEN to meet the flow rate mentioned above. Please refer to chapter 8.2.5.1. for detail calculation and design. Drum Filter 1 and 2 (S301 and S302)

As it is mentioned above, detail simulations for designing the filters are done by sub simulations. In this main simulation component separator ‘Sep’ is used. Please refer to Table D.1.6, Appendix D.1 for the split fractions. It is assumed that amounts of bounded water and glucose are proportional to amount of another solid components such as chitin, chitosan, calcium carbonate, and protein (S). Therefore following demineralization and deproteinization, bounded water and glucose are also released to the liquid phase. Liquid fraction in cake is assumed as 20 % in mass basis. This 20 % of liquid is calculated based on all the solid materials including bounded water and glucose. Therefore the rest of the liquid components are separated proportionally based on the total amount of liquid in the cake. Also 1 % loss of solid materials is estimated at filters. Drum Filter 3 (S401)

Drum filter 3 (S401) consists of 2 separate parts. As first step, sodium hydroxide rich liquid phase is separated from cake, which consists of chitosan particles. This first step is simulated based on the same assumption for drum filter 1 and 2. Second step is washing cake/particles by water. In volume base, 3 times of water to the solid is used for further washing. It is assumed that 99 % of liquid components are washed out in this process except free water. Liquid fraction in cake is set as 20 % following same assumption that used for other filters. For both steps, ‘Sep’ is used in ASPEN. Please refer to Table D.1.6, Appendix D.1 for split fractions. CO2 Purge (Purge1 and Purge2) CO2 is formed through the demineralization reaction. Therefore purge of CO2 gas is needed in enzymatic demineralization and deproteinization reactor, and chitin purification (chemical demineralization) reactor. In ASPEN purge is installed after the reactors for the simulation convenience, while in the real reactor designing purge pipe are installed for all the sections in reactors. Solubility of CO2 at 25 ºC is 9.98×10-4 kg-CO2/kg-water and at 40 ºC is 1.139×10-3 kg-CO2/kg-wate. [1] In ASPEN ‘Sep’ is used for this unit based on solubility of CO2 in water. Please refer to Table D.1.6, Appendix D.1 for design specification.


CPD 3264 8-7

Product Dryer (D401)

‘Sep’ is used for the product dryer. 100 % H2O-Free of and 90 % of H2O-Bound is assumed to be dried out through this dryer. To estimate the temperature of the dryer, ‘Flash’ unit is used in ASPEN for test dryer. Please refer to section ‘Test product dryer’. Vacuum drying with 0.05 atm takes place in this unit. Temperature is estimated to meet the specification mentioned above. However in the flash calculation, ASPEN cannot distinguish the difference with H2O-Free and H2O-Bound. Therefore by trial and error, the operating temperature is chosen when the total amount of water (H2O-Free and H2O-Bound) staying with particle in flash calculation equivalent to 10 % of H2O-Bound which is assumed to be with particle. Please refer to Table D.1.6, Appendix D.1 for design specification. Cooler, heater and pump (E201, E202-3, E402, E403, P402, EDryer1, EDryer2)

For cooler, heater and pressurization pump, ‘Heater’ is used in ASPEN simulation. ‘Heater’ is thermal and phase state changer. Specifications of the units are described in Table D.1.7, Appendix D.1. E201 Pressure is set as 1 atm and vapor fraction is set as 0 for E201. To minimize the heat duty of ethanol flash distillation (C201), heat exchange is attempted before the stream is fed into ethanol flash distillation (C201). For fear of deposition of benzoic acid, which might be caused by the vaporization of solvent (water and ethanol), temperature is set as 77 ºC, which is lower than boiling points of ethanol. E202-3 and E403 E202-3 and E403 are cooled by cooling water, which is 25 ºC. Because of the restriction about the minimum temperature deference of heat exchange, temperatures are set as 35 ºC, which is 10 ºC higher that that of cooling water. Heat duties are described in Table SS. P402 The chitin deacetylation reactor (R401) is operated at 2.3 atm. P402 is the pressurization pump before this reactor. The feed stream should have higher pressure; therefore pressure is se t as 2.5. E403 The chitin deacetylation reactor (R401) is operated at 121 atm, hence temperature of E403 is set as 121 ºC. EDryer1 and EDryer2 EDryer1 and EDryer2 are operated in 0.05 atm and 37 ºC. These conditions are determined through the test simulation for dryer. Please refer next section, which is about this test simulation. Please refer to Table D.1.7, Appendix D.1 for design specification. For the ASPEN stream summary, please refer to Table D.1.8 a/b/c/d, Appendix D.1. Note that the stream numbers here do not correspond to the streams in the block diagram or PFS diagram. Refer to Figure D.1.1 for corresponding stream names.


CPD 3264 8-8

8.2 Equipment Selection and Design The calculation details will be divided into groups, i.e. sections for reactors, filters, grinders, heat exchangers, vessels and pumps. 8.2.1 R101 a/b Lactic Acid Fermentor and S101 a/b Microfilters

Figure 8.2.1 Chemostat for fermentation

Fermentation will be done continuously in a chemostat (CSTR), Fig 8.2.1 equipped with Temperature controller (for constant temperature operation) and pH controller (for constant pH operation). The reactor size is mainly determined by the dilution factor. From Appendix D.2, equations D.2.11 to D.2.14, the mass balance is given as:

max

0

(8.2.1)

( )(8.2.2)

(8.2.3)

SS

S Sx

S

XP P

K DC

D

D C CC

q

CC q

D

(Meaning of symbols can be found in Appendix D.2) By solving the above equations simultaneously, the reactor volume can be determined from

LDV

. However, before the dilution rate can be determined, the reaction conditions need to be

determined. The reaction conditions considered are the pH and the operating conditions. These two factors will determine the stoichiometry of the reactions, as Gcat and Greac needs to be corrected for each pH range. The maintenance and specific growth rates are a function of temperature. From the equations below, Appendix D.2 Table D.2.1 is obtained for reaction conditions at different pH and temperatures. From this table, it is concluded that fermentation will be done at pH = 5.5 and T = 40C. Further increase in temperature or pH does not give sufficient benefits to outweigh the cost of operation and a decrease in pH or temperature does not give a high product efficiency.

1

5

2

3

Cooling water in

Innoculum

N2 in

N2 out

Cooling water out

4


CPD 3264 8-9

Gcat,

(pH new)cat (pH new) cat (pH = 7)

(pH=7)

KG = G + RT ln

K (8.2.4)

Greac

(pH new)react (pH new) react (pH = 7)

(pH=7)

KG = G + RT ln

K (8.2.5)

maintenance

GibbsS Gibbs

cat new

m 69000 1 1 = ; m 4.5 exp - -

G 8.314 T 298m

(8.2.6)

specific growth

catmax

Gibbs new

3 - G 4.5 69000 1 1 = exp - -

G 8.314 T 298

(8.2.7)

but as this process is a substrate level phosphorylation process, the calculation will under estimate max. Therefore max from reference will be taken as standard, max = 0.4 /hour at pH = 6 and T = 30C [2]. The list of symbols can be found in Appendix D.2.

The final stoichiometry is:

1.36 C6H12O6 + 0.1 (NH4)SO4 CH1.8O0.5N0.2 + 2.370 C3H6O3 + 0.1 H2SO4 + (8.2.8) 0.05 CO2 + 0.45 H2O From the stoichiometry, the required input can be determined based on the required lactic acid needed for demineralization and deproteinization, i.e. 10.660 kC-mol/hour. Matlab simulation is then carried out to determine Cs, Cx and Cp. From Fig D.2.1 in Appendix D.2, it can be seen that Cs and Cp does not change much until after dilution factor increases above 0.7 hours. After this dilution factor, washing out of biomass occurs and production rate decreases. Hence it is decided that D = 0.6 h would give the highest conversion, smallest volume and within safety range of microorganism washout. Next a recycle of the unused substrate and biomass is determined. From Fig D.2.2 in Appendix D.2, the best recycle fraction without increasing the volume of reactor by a substantial amount would be at about 80 %. At this recycle fraction, product concentration also increases. Finally the dimensions of the reactor are carried out.

Fermentor volume = %

inQ D

working volume number of fermentor

(8.2.9)

Taking 75 % as working volume, fermentor volume is 3.41 m3 with D = 1.425 and H = 1.5 D. Cooling requirements is by using cooling water at in = 20 C and out = 30 C. Superpro designer simulation is carried out to determine the accuracy of the calculation and also the power requirements for impeller. It is notice that the calculated results are similar to the run in Superpro Designer simulation.


CPD 3264 8-10

Calculation details can be found in Appendix D.2, Chapter D.2.j. R101 and R102 contains mild acids of lactic acid and H2SO4. Hence, the material used for construction should be of anti-corrosive materials. The suggested material is Stainless steel 304. This material is able to resist corrosiveness at the minimum cost. As for the microfilters, the design is based on 80 % biomass recycle needed for the fermentor. The area requirements are calculated using Superpro Designer (Appendix D.2. Chapter D.2.j). The microfilter is a membrane filter based on the following dimensions:

a. Hollow fiber membrane with 1.5 mm diameter fiber at 1 m length b. 3000 hollow fibers in one tube

From these specifications, the total area provided by one tube can be determined, and hence the number of tubes required is established. From the detailed calculations in Appendix D.2., each microfilter consist of 4 tubes. The microfilter vessel is also constructed with SS304, with the same reasoning with the fermentors.

8.2.2 R301a/b, R302 and R401 Reactors

8.2.2.1 Reactor configuration

Tube reactor with stirrers and baffles can be assumed as CSTRs in series. To design a tube reactor with baffles, it is necessary to know the required number of baffles for uniform residence time distribution. In CSTRs, the flow patterns are not idealized plug or mixed flow but tend to involve channeling of liquid, and the existence of stagnation, dead zones in the reactor. As alternative, we may simply increase the size of reactors to ensure the product convergences. However it is not an option, because of the fear of chitin and chitosan polymer decomposing in strong acid or base conditions. Therefore it is necessary to design in proper scale. In scale-up, it is possible to determine the reactor performance by quantifying the non-ideality of the flow. This is done by evaluating the exit age distribution function, E, also referred to as the residence time distribution, or RTD. To design the reactor configuration, we set our product specification as follows.

‘90 % of the particles have their conversions in the range of 10 % deviated from the specifications. The specifications are 90 % demineralization is R301 a/b, 95 % demineralization in R302 and 90 % deacetylation in R401.’ Two analyses are taken to design the configuration of reactor with first order reaction. Two analyses are followings.

1. Reacting time (residence time) and conversion in batch system 2. Residence time distribution for CSTRs in N series

8.2.2.1.1 Reacting time (residence time) and conversion in batch system


CPD 3264 8-11

As it is mentioned, each particle can be assumed as a small batch system. Relation between conversion and reacting time (residence time of each particle) is described as follows. For instance, if first order reaction is applied for this calculation, the relationship between reaction time and conversion is described as equation 8.2.10 and is drawn as Figure 8.2.2. Time is normalized based on the time needed for 99 % conversion.

0

0

Af

A

x

AA

Ax

dxt C

r

(8.2.10)

In which, t is reacting time [s], xA0 [-]is conversion of feed, xAf [-]is conversion of outlet, CA0 is feed concentration [kmol/m3], and rA is reaction rate [kmol/s].

Figure 8.2.2 Reacting time against conversion Our specifications of reactors R301 a/b and R401 are 0.90 conversion and R302 is 0.95 conversion. To reach 0.90 conversion, 0.50 t99 is needed, and to reach 0.95 conversion 0.65 t99 is required. As it is mentioned, 10 % deviation from the specifications are allowable in our design. To reach 0.81 conversion, which is 10 % deviated from 0.90 conversion, 0.35 t99 is required. Results are summarize for 0.90 and 0.95 in Table 8.2.1.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Conversion [-]

Rea

ctin

g tim

eN

orm

aliz

ed b

y 0.

99 c

onve

rsio

n [-

]


CPD 3264 8-12

Table 8.2.1 Reacting time specifications

Specification tA. Required time for specification

tB. Required time for 10 % less conversion

tB/tA

0.90 0.50 t99 0.35 t99

(0.81 conversion)

0.70

0.95 0.65 t99 0.41 t99

(0.85 conversion)

0.63

If we design our reactor based on specification, tA is set as mean residence time of the reactor. 90 % of the particles should stay longer than tB to have conversion in the range of 10 % deviated from the specification. 8.2.2.1.2 Residence Time Distribution for CSTRs in N series Residence time distribution of CSTRs in series can be described as follows.

( 1)1 1

( ) exp( 1)!

N

i i i

t tE t

Nt t t

(8.2.11)

In which t represents time, N is the number of CSTRs, it is mean residence time of each reactor.

Figure 8.2.3 Residence time distribution in CSTRs Residence time distributions of CSTRs in series are drawn as in Figure 8.2.3. In Figure 8.2.3, residence times are normalized for each case. This figure shows that with increasing number of CSTRs in series, the residence time distributions becomes more uniform and less distributed.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 0.5 1 1.5 2 2.5 3

N=1

N=2

N=3

N=5

N=10

N=20

N=15

Mean Residence Time

E(t)

time

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 0.5 1 1.5 2 2.5 3

N=1

N=2

N=3

N=5

N=10

N=20

N=15

Mean Residence Time

E(t)

time


CPD 3264 8-13

As it is mentioned, 90 % of the particle should stay longer than tB. Based on this criteria and cumulative residence time, F (t), 16 sections is needed to ensure the product uniformity. Please refer to Appendix D.3 for further details. 8.2.2.2 R301 a/b Chitin Demineralization and Deproteinization Enzymatic demineralization and enzymatic deproteinization take places in this first reactor. The temperature is kept at 25 C, because of the concern of enzymes (proteases in shrimp shell) for deproteinization. The shrimps are caught in North Sea, therefore it is not advisable to set temperatures too high for the fear of denaturing the proteases. The concentration of lactic acid is operated higher than 3 kg/m3 to in order for demineralization to proceed effectively. Under these conditions the second stage of the enzymatic demineralization kinetics can be applied. In our plant 7.65 tonne/day of lactic acid is fed into the reactor to maintain high enough concentration of lactic acid through the reactor. Initially lactic acid concentration is 88 kg/m3, and it is consumed by demineralization reaction until 17 kg/m3. This reactor is operated at ambient pressure (1 atm), because the reactions take place in liquid-solid phase, which have few effects of pressure on reaction acceleration. Based on these considerations, operating conditions are set as 25 C, 1 atm with 88 kg /m3 initial lactic acid concentration. This reactor is designed to meet the specification for demineralization. The specification is set 90 % of demineralization, which is based on the initial concentration of minerals. Reactor configuration is determined through the residence time distribution analysis. Tube reactor with 15 baffles (16 sections) is chosen. The reactor size is estimated by ASPEN simulation, and it is calculated as 14.2 m3 including 15 % safety factor for design. In this reactor, carbon dioxide gas is generated through the demineralization reaction. Free space (safety factor space) and the purge of gas are needed for each section, because of the carbon dioxide generation through demineralization. Each section of this tube reactor can be estimated as a CSTR, hence the diameter and height ratio of each section (D/L) is set as 1.5. This ratio, 1.5, is recommended for the tank reactor. [3] Diameter of the reactor is calculated as 0.91 m, length of one section is 1.37 m, and total length of reactor is 21.8 m. Because of the ease of maintenance and geometrically hugeness, this reactor is designed to separate into two parts. They are connected in series, and the length of each part is 10.9 m. Figure 8.2.4 shows the reactor design.


CPD 3264 8-14

Figure 8.2.4 R301 a and R301 b PFR reactors

Safety factor for design is set as 15 %, and it means that hold up of each section is 85 %. The vertical cross-section images of the reactor are shown in Figure 8.2.5.

Figure 8.2.5 Cross-sectional image of R301 a/b

Impeller diameter is one-third of the reactor diameter, D. Vapor phase fills 21 % of the reactor diameter from top (based on 85 % hold up). Therefore the impellers rotate in liquid phase not in vapor phase and the medium can be mixed effectively. Calculation of the empty space is shown in Appendix D.3. Impeller duty is calculated in Appendix D.3. As it is mentioned above, heat exchange is necessary to keep temperature constant at 25 C (operating isothermally). Cooling duty of this reactor is -114 kWatt and it is equivalent to heat of reaction, which is exothermic.

0.91 m

10.9 mFeed

Outlet

0.91 m

10.9 mFeed

Outlet

D 1/3 D

Dehydrater

Residence part Baffle

0.21 D

D 1/3 D

Dehydrater

Residence part Baffle

0.21 D


CPD 3264 8-15

8.2.2.3 R302 Chitin purification with hydrochloric acid

Chemical demineralization, which hydrogen chloride reacts with calcium carbonate, takes place after the enzymatic chitin demineralization and deproteinization. This reactor is operated adiabatically, without any heat exchange. It is because of no significant effect of temperature on reaction rate is observed in chemical demineralization [4]. Temperature increases slightly from the beginning toward the end of the reactor, due to chemical demineralization, which is an exothermic reaction. The optimum condition for chemical demineralization is reported as 1.7 N hydrogen chloride, with solution-solid ratio of 9 ml/g (dry basis) [4]. The reactor is designed to operate at 0.5 N hydrogen chloride, with solution-solid ratio of 5 ml/g in wet basis. As it is mentioned in Appendix A, 5 ml/g in wet basis can be expressed as 10 ml/g solution-solid ratio in dry basis. Therefore the amount of hydrogen chloride in the reactor is 5 [N·l-solution/kg-solid], which is 0.5 N multiplied with 10 ml/g solution-solid ratio in dry basis. Same reactor configuration with chitin demineralization and deproteinization is applied for this reactor, which is plug flow reactor with 15 baffles (16 sections) based on the residence time distribution analysis. Design specification for this reactor is 95% of demineralization based on inlet mineral concentration. Total reactor volume is calculated as 1.55 m3 with 15 % safety factor for design through ASPEN simulation. The reactor diameter is calculated as 0.43 m, the length of one section between baffles is 0.65 m, and total length is 10.4 m. According to the ASPEN simulation, temperature increases from 25 ºC to 40 ºC, from first section to last section in reactor, due to the heat of reaction. 8.2.2.4 Chitin deacetylation and deproteinization with sodium hydroxide As the final step of reactions, chitin deacetylation and deproteinization, with sodium hydroxide, occur after chitin purification with hydrogen chloride. Chitosan is generally prepared by treating chitin with 50 % sodium hydroxide solution, usually at 100 C or higher to effectively remove the acetyl groups. During acetylation, conditions must, in a reasonable time, sufficiently deacetylate chitin to yield a final chitosan specification of 90 % degree of deacetylation. It was reported that deacetylation was effectively achieved by treatment of chitin under elevated temperature and pressure with 45 % sodium hydroxide for 30 min and solution-solid ratio of 10:1 under autoclaving conditions, which is 121 C and 15 psig (1.02 atmg). Therefore this reaction is operated at 121 C and 2.3 atm with 45 % sodium hydroxide solution. Pressure is set 10% higher than the autoclave experiment to prevent water boiling certainly. Deproteinization also takes place in this reactor. The optimal deproteinization condition was reported as 75 C, 2.5 N of sodium hydroxide with a minimal solution to solid ration of 5:1 (dry basis) to maintain fluidity during deproteinization. [4] In this reactor the concentration of sodium hydroxide is 45 weight %, which is 19.8 N of sodium hydroxide. 2.5 N is the maximum concentration that they [4] have examined, therefore it is drawn in that higher concentration of sodium hydroxide accerelates the reaction. It is assumed that the kinetics of deproteinization is proportionally depending on the concentration of sodium hydroxide. Same reactor configuration is applied for this reactor, which is plug flow reactor with 15 baffles (16 sections) based on the residence time distribution analysis. This reactor is designed to meet the specification that is 90 % degree of deacetylation. Total reactor volume is simulated as 2.34 m3 with 5 “RCSTR” in ASPEN. This reactor volume is determined as reactor volume with 15 % safety factor for tube reactor with 15 baffles. In this reactor, deproteinization proceeds until 97.8 %. Hence, the reactor diameter is calculated as 0.50 m, the length of one section between baffles


CPD 3264 8-16

is 0.75 m, and total length is 12.0 m. In this reactor, no gas is generated therefore purges are not necessary.

Figure 8.2.6 R401 Deacetylation Reactor

8.2.2.5 Material of construction R301 a/b and R401 are constructed with stainless steel 304, because of the contact with mild acids and alkaline solution. R302 on the other hand contains chlorinated compounded which would be advisable to use stainless steel 316, a higher-grade stainless steel that can withstand more corrosive conditions.

Feed

Outlet

0.50 m

12 m

Feed

Outlet

0.50 m

12 m


CPD 3264 8-17

8.2.3. S301, S302 and S401 Vacuum Rotary Drum filters The drum filters work as separators for liquids from solids. In our design, the solids which contain chitin and chitosan are the important components, and hence, special care is taken when handling with the solids. Essentially, a multi-compartment drum type vacuum filter consists of a drum rotating about a horizontal axis, arranged so that the drum is partially submerged in the trough into which the material to be filter is fed. The periphery of the drum is divided into compartments, each of which is provided with a number of drain lines; these pass through the inside of the drum and terminate as a ring of ports covered by a rotary valve, through which vacuum is applied. The surface of the drum is covered with a filter fabric, and the drum is arranged to rotate at low speeds, usually in the range of 0.1 to 0.25 rpm. As the drum rotates, each compartment undergoes the same cycle of operations, the duration of each of these being determined by the drum speed, the submergence of the drum and the arrangement of the valve. The normal cycle of operations consists of filtration, drying and discharge. However it is also possible to introduce a wash to the filter cake where purity of the cake is important. For the first two filters, S301 and S302, washing is not required. Only the last filter, S401, washing is included. (Figure D.4.2 in Appendix D.4) Below are the general operating filter specifications. Table 8.2.2: Filter Specifications Filter S301 Filter S302 Filter S401 Rotation speed, rpm 0.25 0.25 0.2 Percentage area submerged 37.5 37.5 37.5 Pressure drop, -P N/m2 4104 4 104 4 104 Time per rotation, s 240 240 300 Zoning, % Filtering Washing Dewatering

37.5

- 62.5

37.5

- 62.5

37.5 31.25 31.25

Assumptions made:

1. Incompressible cake 2. The resistance to flow of a given volume of cake is not appreciably affected either by the

pressure difference across the cake or by the rate of deposition of material 3. Constant filtrate rate 4. Recovery of solids is 99 % 5. Porosity of cake is 40 % and liquid fraction is 20 %. 6. Values of filtrate and cake volumetric flow rate are taken from ASPEN PLUS. 7. Solids and liquid densities are taken from ASPEN PLUS simulation.


CPD 3264 8-18

8.2.3.1 Design of the filters The filter is designed based on a constant filtrate rate.

For a filtration at constant rate 2 ( )

t rV

V A P

(8.2.12)

where, t = time of filtration, day V = Volume of filtrate A = Area of filtration -P = Pressure drop across the filter = viscosity of filtrate

= volume of cake deposited by unit volume of filtrate

and 2 2

3

5(1 )e Sr

e

(8.2.13)

where, r = specific resistance, m-2 S = Specific surface of particles, m-1 e = voidage

From these equations, A, the total filtration area can be calculated for the process for one day. However, because the drum is rotating, the total area will be reduced based on the speed of rotation per day. If the rotation speed is 0.25 rpm, a total of 360 rotations are done in a day and hence, the total area can be reduced by 360 times. Optimal drum dimensions are usually with L = 2D. For calculation details, refer to Appendix D.4. For pump power requirements, two pumps need to be installed. One filtrate pump to pump the filtrate from vacuum conditions to atmospheric conditions, and one to create the vacuum (Figure D.4.1 Appendix D.4).

Pump efficiencypP Q

Power

(8.2.14)

Pump efficiency is estimated at 50 %. [5] Summary of the filter specifications can be found on Table D.4.2 in Appendix D.4. Material of construction of each filter is different due to the changing corrosiveness of the streams being filtered. For S301, the presence of mild H2SO4 and lactic acid would suggest a basic SS304. S302 is in contact with concentrated HCl. The chlorinated stream is highly corrosive and hence SS316 is required. Finally, S401 is in contact with concentrated NaOH. Carbon steel is resistant to corrosion in specific environments like with NaOH. Hence S401 can be constructed with carbon steel.


CPD 3264 8-19

8.2.4 A201 Shrimp shell crusher and A401 Chitosan grinder 8.2.4.1 A201 Shrimp shell crusher The shrimp shells are initially crushed in order to reach a larger surface area and uniformed particle size that will eventually determine the size and quality of the product. It is assumed that the shrimp shells have an average length of 3 cm, for which the shells will be crushed to approximately 1 mm (16 mesh) in size.

Energy consumption is calculated by Bond law, for intermediate particle sizes:

2 1

1 1100 iE E

x x

(8.2.15)

where E is the energy consumption, kWh/ton

Ei is the Bond work index, kWh/ton x1 is the feed particle size, mm x2 is the product particle size, mm

Calculation details are seen in Appendix D.5, Chapter D.5.a.a.

As for the design of A201, the structure of the crusher is of a ball mill. The size reduction of the feed from 30 mm to 1 mm is of large order of reduction. Hence, in order to optimize the size of the ball mill, the Hardinage mill is used. This mill is composed of balls of different sizes that segregate themselves according to size. The main portion of the mill is cylindrical, like the ordinary ball mill, but the outlet end is conical and tapers towards the discharge point. The large balls collect in the cylindrical portion while the smaller balls, in order of decreasing size, locate themselves in the conical portion as shown in Fig 8.2.7. The material is therefore crushed by the action of successively smaller balls, and the mill is thus similar in characteristics to the compound ball mill. The balls are initially mixed, but eventually the large ones will attain a slightly higher falling velocity and therefore strike the sloping surface of the mill before the smaller ones, and then run down towards the cylindrical section. The Hardinage mill gives uniform and fine products with a lower consumption of power.


CPD 3264 8-20

Figure 8.2.7 : The Hardinage Mill

The ball sizes are calculated from, 0.46919.931Ball size Feed size , where ball and feed size is in

mm. The residence time is taken as 22 mins, based on experimental data in [6]. The proportion of feed is estimated as 85 %, 10 % and 5 % in Zones 1,2 and 3 respectively and the ratio of balls to feed volume is estimated as 35, 150 and 200 in the respective zones. Hence, the volume of balls can be calculated with the above criteria. Taking the percentage of balls in the vessel of 50 %, the total vessel volume, V =43.5 m3 is determined.

The speed of rotation is taken from 65 % of the critical rotational speed which is defined as:

Critical rotational speed =42.3

Drpm, (8.2.16)

where, D is the diameter of cylindrical section in m

Calculation details in Appendix D.5, Chapter D.5.a.b. The final dimensions of the vessel can be seen in Fig D.5.1, Appendix D.5.

The crusher vessel is made of normal carbon steel as the inner layer is lined with rubber. Rubber is chosen as the inner liner as this material gives good absorbance impact when the balls fall during rotation and hence reduce the wear and tear of the balls and the vessel. Rubber materials also give the balls a good surface friction, and hence the balls are carried higher before submitting to gravitational forces. This gives a higher impact and better crushing. Steel balls are chosen as it is the hardest and cheapest material for internal materials.

Feed (30 mm)

Solids: 20.7 t/day

Water: 9.3 t/day

Product (1 mm)

Solids : 20.7 t/day

Water : 9.3 t/day

Zone 1

Proportion of feed : 85 %

Feed size : 30 mm

Ball size : 98 mm

Zone 2


Feed size : 10 mm

Ball size : 59 mm

Zone 3

Proportion of feed : 5%

Feed size : 3 mm

Ball size : 35 mm

Feed (30 mm)

Solids: 20.7 t/day

Water: 9.3 t/day

Product (1 mm)

Solids : 20.7 t/day

Water : 9.3 t/day

Feed (30 mm)

Solids: 20.7 t/day

Water: 9.3 t/day

Product (1 mm)

Solids : 20.7 t/day

Water : 9.3 t/day

Zone 1


Feed size : 30 mm

Ball size : 98 mm

Zone 2


Feed size : 10 mm

Ball size : 59 mm

Zone 3

Proportion of feed : 5%

Feed size : 3 mm

Ball size : 35 mm


CPD 3264 8-21

8.2.4.2 A401 Chitosan Grinder

After the dryer, the product is sieved through a mesh and only particle with sizes below 40-60 mesh are accepted. The particles that have larger sizes are sent to be grinded for one final time before sieved again. Fig 8.2.8 shows the process.

Figure 8.2.8: Fine grinding

A ball mill is used for this process. Again, the ball mill is suitable for this operation to reduce the particles to very small particles of about 50 mesh (50 micron).

Assumptions made:

1. The average feed size to the fine grinder is 100 mesh (100 micron). 2. Percentage of solids above required product size is 70 % 3. Percentage of solids from the fine grinder that needs to be crushed again is 10 % 4. Residence time of solids in the ball mill is 10 minutes 5. Percentage of balls in vessel is 50 % the vessel volume 6. The speed of rotation is 65 % from its critical rotational speed 7. Ratio of volume of balls to feed volume is 250

The same design method and formulas employed for A201 is used for the design of A401. The only difference is that A401 is a typical ball mill in cylindrical shape with one ball size. Calculation details can be seen in Appendix D.5.b. The same materials are use for A401 as with A201 and with the same reasoning.

Feed <1905 kg/day>

Fine Grinder

<1470 kg/day>

40-60 mesh

Chitosan product <1905 kg/day>

Feed <1905 kg/day>

Fine Grinder

<1470 kg/day>

40-60 mesh

Chitosan product <1905 kg/day>


CPD 3264 8-22

8.2.5 Heat Exchangers and evaporators

8.2.5.1 C201 Ethanol Evaporator

The evaporator design consist of two parts, the vessel for evaporation and the heat exchanger to generate the energy to evaporate the ethanol for recovery.

Vessel for evaporation

The column diameter is based on the velocity of the vapour. Based on Souders and Brown equation, Lowenstein (1961), the maximum allowable superficial vapour velocity, umax[7]:

2( 0.171 0.27 0.047) ( )max

u l lL v v

(8.2.17)

where, l = vapour space, m L = liquid phase density, kg/m3 v = vapour phase density, kg/m3

Vapour space l = 0.5 m is assumed, and vapour velocity, u is taken as 10 % umax. From this, the column diameter, Dc is calculated from:

4 wc

v

VD

u (8.2.18)

where, Vw = Vapour mass flow rate, kg/s

Dc is calculated as 0.3 m, and the height, H = 2Dc.

Heat Exchanger

The heat exchanger used is a 1-pass tube and shell heat exchanger. Low pressure steam at 3 bara is used as the heat exchanger media, which is introduced from the tubes.

Heat duty from ASPEN PLUS is Q = 14090 W. The amount of steam required is calculated from:

Q = MCpT + Mhev (8.2.19)

where, Q = heat duty, kJ/s M = Mass flowrate of steam, kg/s Cp = Specific heat capacity, kJ/kg C T = Temperature difference of steam in and out, C hev = Enthalpy of evaporate, kJ/kg

Steam properties are given in Appendix D.6.a, Table D.6.1.


CPD 3264 8-23

Heat exchanger design for a shell and tube exchanger is done as described in the text of Coulson and Richardson Volume 6.

Figure 8.2.9 : Calculation procedure for heat exchanger design

Estimate di and L of tubes Across =

2

4id

Guess U, Overall heat transfer coefficient

Calculate A, Area required for heat

transfer

Known Steam vol. flowrate, m3/s

Velocity in tubes, ut

No of tubes required

Atube = 2do cross

Volumetric flowrate of steam

A no. of tubes

Shell inside diameter Ds = 0.02(8/0.215)1/2.207 + 10

Tube side P 2

8 2.52

m

tt p f

i w

uLP N j

d

NO

Shell side P (Kern’s Method) 0.142

82

s ss f

e B w

D uLP j

d l

Guess Baffle spacing

NO

OK

Check guessed U

ln1 1 1 1 1

2

oo

i o o

o o od w i id i i

dd

d d d

U h h k d h d h

OK

FINAL DESIGN ACCEPTED OKNO


CPD 3264 8-24

Calculation details can be found in Appendix D.6 and the final evaporator design on Fig D.6.3. The material of construction of the vessel is SS304 as the is the presence of benzoic acid, which may be corrosive. The tubes used are also constructed with SS304. 8.2.5.2 Heat Integration and Heat Exchanger Chitosan production process is such a big and complex process. All main reactions are exothermic. Some of them require a constant high-temperature or the product released is in high temperature or even the feed needs preheating. There is also the sterilization of fermentation raw material and evaporation system for ethanol recovery that requires quite a big amount of energy. Considering the environmental effect of high-energy consumption and since energy cost is a significant factor in operating cost, energy saving by application of heat integration techniques becomes an interesting alternative to be considered. Table 8.2.3 Potential candidates for heat integration

System Stream numbers Process condition

Sterilization 102 – 104 107 - 109

Sterilization condition : 140°C, 3 bar maintained for 2’ minutes

Ethanol evaporation 207 – 213 Evaporation at 87°C, 1 bar

Chitin deacetylation 404 – 410 121°C, 2 bar

8.2.5.2.1 Sterilization system Sterilization can be divided into media sterilization and apparatus sterilization. Apparatus sterilization (fermentor, piping, filter, etc) should be done at every start up of operation. While to maintain sterilization during the process operation, it is important to do media sterilization and to do the operation aseptically. The goal of media sterilization process is to kill or to clean the fermentation media from any unwanted microorganisms. In this plant aqueous media sterilization will be done by wet heat (steam) while the gas sterilization will be done by filtration (depth filter filtration system). General guide for wet heat sterilization is shown in Table 8.2.4.

Table 8.2.4 Wet Heat Sterilization Condition [8] T (°C) Minimal Time required

(min) 121 15 126 10 134 3 140 0.67

It is also important to separate separation process of sugar (glucose etc) from nitrogenous material to prevent the occurrence of Maillard reaction between carbonyl groups from carbohydrate and amine groups. Therefore we separate these two stream, and add 75% of water to glucose stream and 25% of water to N-source.


CPD 3264 8-25

In this design the latest operating condition is used, heating up until 140°C, maintain the temperature during 2 minutes, and cooling down until fermentation operating temperature. For energy saving system heat integration possibility is reviewed (Figure 8.2.10). Graphical scheme of heat exchanger network design is presented in figure 8.2.10.

Figure 8.2.10 Heat exchanger network for sterilization system Sterilization is performed on plate heat exchanger. Detailed calculation is presented in Appendix D.6.b.a. The exchanger is calculated based on:

Number of Tansfer Unit (NTU) = = i o

m

t t UA

t mCp

-=

D (8.2.20)

ti = input temperature of fluid to = ouput temperature of fluid tm = mean logaritmic temperature difference = tLMTD x correction factor (F) U = overall heat transfer coefficient A = heat transfer area m = mass flow rate of fluid Cp = specific heat of fluid Because the exchangers are used for sterilization, the material of construction is stainless steel 304. This is to ensure a clean and sterile condition. 8.2.5.2.2 Ethanol evaporation system Evaporation is one of energy intensive system. This process is conducted at 87oC and 1 bar. It was design that the feed is preheated until 70C. And further heating is done in the evaporator, by the means of steam (low pressure). Afterwards top product of this unit is condensed and cooled down until 35C and mixed with fresh ethanol. There is a chance to exchange heat between top product to be condensed and feed to be preheated. Heat integration calculation results are presented as heat exchanger network design in figure 8.2.11.

HE 1 HE 2

Steam,

25oC 120°C 140oC

140oC

43°C

Holding : 2 min


CPD 3264 8-26

Figure 8.2.11 Heat exchanger network design for ethanol evaporation system

Type of heat exchanger used is double pipe heat exchanger, because the heat duty for each exchanger is quite small. Detailed calculation is presented in Appendix D.6.b.b. Double tube calculations are based on:

LMTDQ m Cp T U A T F (8.2.21) Q = heat duty M =mass flow Cp=specific heat T=delta temperature TLMTD =logaritmic mean temperature different U=overall heat transfer coefficient A=heat exchanger area F=correction factor for double pipe heat exchanger, F = 1 The heat exchanger system is neither in any extreme conditions nor mild acidic conditions. Hence carbon steel may be used for construction. 8.2.5.2.3 Chitin Deacetylation system Chitin deacetylation system is one of the most important part of the process, it converts chitin to chitosan. This process is conducted at 121oC and 2 bar. Because the reaction occurs quite in a short time, the feed should be preheated first until 121C. Further to prevent damage to environment the reactor output should be cooled down first to a reasonably acceptable temperature. In this heat network, we are using the heat available in the reactor output stream to preheat the feed and in the same time, cooled down the product stream. Heat integration calculation result were presented as heat exchanger network design in figure 8.2.12.

E201

E203

E202

77oC

25oC 87.2oC

87.2oC

72.2oC

Cooling water

35oC

LP steam


CPD 3264 8-27

Figure 8.2.12 Heat exchanger network design for chitin deacetylation system Considering quite big amount of heat transferred, type of heat exchanger used here is shell and tube, with 1 shell pass and 2 tubes pass in E402 and E403 and 3 shell pass and 6 tube pass in E401 to perform high heat transfer efficiency. Detailed calculation are presented in Appendix D.6.b.c. Calculations for shell and tube exchanger is based on:

LMTD

QA

U T F

(8.2.22)

A = Area of heat exchanger, m2 Q = Heat duty of heat exchanger, W U = Overall heat transfer coefficient, W/m2 C TLMTD = Log mean temperature difference, C F = Correction factor, - The presence of concentrated NaOH prevents corrosion. Hence carbon steel is used as the material of construction. 8.2.6 Vessels On the plant there are mainly 5 main vessels other than the reactors. These include S201 Benzoic acid extractor, D401 product dyer, T101 Lactic acid buffer tank, T201 Ethanol Buffer tank, V301 HCl chitin mixer and V401 NaOH chitin mixer. 8.2.6.1 S201 Benzoic acid extractor Leaching is concerned with the extraction of soluble constituent from a solid by means of a solvent. In this process, 1 % Benzoic acid is removed from shrimp shells. A solution of ethanol 75 %, water 25 % is used as a solvent. The extraction is carried out at 25 C at 1 atm.

Basic assumptions 1. Benzoic acid is not part of the shrimp shells, but mixed well with the shells. The size of

the shells are approximately 1 mm, the size of the crushed shells from the crusher. 2. The effective thickness of the liquid film surrounding the particles is 1 micron. 3. The diffusion coefficient, k’ is 1.21 109 m2/s [9] 4. Solid fraction is insoluble in solvent

E402

E403

E401

121oC 25oC

43.8oC 121oC

106oC

Cooling water

25oC

LP steam


CPD 3264 8-28

5. Density of solids is 1165 kg/m3 (ASPEN PLUS) 6. 99 % Benzoic acid recovery 7. H20 that accompanies the solids enters and leaves with the solids. It does not separate into

the solvent stream. 8. 5 % of the solvent is lost with the solids

Table 4.4.1 gives the basic properties of the solvent. Here, the density is taken as 830 kg/m3 and the solubility of benzoic acid of 299.7 kg-Benzoic acid/m3-solvent. From the solubility, to remove 300 kg of benzoic acid, 1 m3 of solvent is required. i.e. approximately 750 kg-ethanol and 250 kg-H20 solvent mix. To ensure that the system is not working on its limits, extra solvent is used. Solvent is about 40 % in excess to ensure saturation is not reached. Before the dimensions of the equipment can be investigated, the number of stages required for the extraction is calculated.

The number of stages, n is calculated from:

1log 1 ( 1)

1log

Rf

nR

(8.2.23)

where, Amount of solvent discharged in the overflow

Amount of solvent discharged in the underflowR

, given S is the solute in kg, n is leaving with the feed and o enteringn

o

Sf

S

Details can be seen in Appendix D.7.a.a. With the number of stages established, the design of the vessel can be done. The basis of determining the mass transfer rate, t is based on the mass transfer of benzoic acid into the solvent.

'ln s o

s

c c k At

c c Vb

(8.2.24)

where A is the area of the solid-liquid interface b is the effective thickness of the liquid film surrounding the particles c is the concentration of the solute in the bulk of the solution at time t cs is the concentration of the saturated solution in contact with the particles co is the concentration of solute at t = 0. k’ is the diffusion coefficient (this is approximately equal to the liquid phase diffusivity) V is the volume of solvent With the assumptions stated above, the solid residence time of 1 minute, and the ratio of solvent to feed in the vessel of one, the solvent and vessel volumes can be determined. The solvent volume is then used to calculate the mass transfer rate. From Appendix D.7.a.b.a, it is noted that the mass transfer only takes 1.1 second. The solvent residence time is calculated from:

ji i

j i j

FV

F V

, where i = solvent phase, and j = Solid phase (8.2.25)

where, = residence time, minutes


CPD 3264 8-29

V = Volume, m3 F = Volumetric flow rate, m3/min The vessel is of cubical shape (Appendix D.7 Figure D.7.3)., with the width x, length y, and depth z, are in ratio of 1:1:1. The working volume is 40 % of the vessel and to keep the residence time of solids for one minute, the speed of rotation is kept at 0.5 rpm. The container that holds the liquid is of hemispherical shape. Calculation details in Appendix D.7.a.b.a. The material of construction is SS304. Again, because of the presence of benzoic acid, a mild acidic solution may be corrosive. 8.2.6.2 D401 Product Dryer Drying step is necessary to bring the product into desired moisture. The required moisture is usually related to the quality, packing, and life-time of the product. Refer to the high quality product specification [Bautista], we set the moisture content of our product to be 7% of total weight.

The cake produced in the drum filter is highly moisture. The water content is 58.5% in which 72.5% of it is bounded water. Our goal is to reduce the water content to 7%.

Heating provided by the steam flows in the jacket (indirect system). Mixing and bulk transport of solids are promoted by the helical faced blades mounted on the agitator shaft. Center tube and paddle arms are also heated to provide more heat transfer area and shorten the drying time. Vacuum condition is necessary to lower the operating temperature and prevent coloring of products. Dimension of vacuum rotary dryer available in the market are between 0.6 – 1.9 m (diameter) and 1.2 – 10.97 m (length).

Figure 8.2.13 Cross section of vacuum horizontal rotary dryer Basic assumption used:

1. effective heating surface = 60% of total area available. 2. extra effective heating surface provided by paddle = 5 – 8 %. total effective heating area = 65% of total area available. 3. volume capacity or working volume = 60% of total volume 4. Heat transfer coefficient = 17 BTU/h ft2 F = 347.5 kJ/h m2 C (usually in between 5 – 55

BTU/h ft2 F) 5. heat transfer efficiency is taken as 1.0 6. evaporation rate = 50 kg H2O/h m3 (typical value is 30 – 80 kg H2O/h m3 ) 7. operating condition :

Steam jacket

paddle

as

Extra heating surface


CPD 3264 8-30

Table 8.2.5 Operating Condition of dryer Parameter Typical condition

Pressure 5 kPa (0.95 bar vacuum) 0.924 – 0.956 bar vacuum Temperature 40°C 35 – 65°C Steam pressure 3 bar Steam temperature 133.54C Heat of condensation 2163.271 kJ/kg

8. Drying period is defined as :

20

25

30

35

40

45

0.0 0.2 0.4 0.6 0.8 1.0L/Ltot

T

1st period: heating up the material until boiling temperature of water at operating pressure 2nd period: evaporation of free water + intial capillary drying 3rd period: heating up of material until wall temperature, capillary drying 4th period: capillary drying at operating temperature Flow Scheme of the drying equipment is as seen in Figure 8.2.14. The product that leaves the dryer goes through a series of separating equipment. The first settler produces the chitosan product (Dry dust collector). The remaining is carried into the wet dust collector, where some solids are lost in this step. The wet gas is then finally condensed in a barometric condenser and released as water.

Figure 8.2.14 Drying flow scheme

2 3

4

1

Rotary vacuum dryer

Wet dust

collector

Barometric condenser

Dry dust

collector

Feed in

Product discharge

to vacuum system

Hot well


CPD 3264 8-31

The dryer dimensions are based on the amount of water needed for evaporation. mwater

feed productw feed w productx m x m (8.2.26)

where m = mass flow rate in kg/h x = mass fraction of water in respective part The energy balance is given by Q = 40 32.9840 25 32.89 25bounded water water evaporation water evaporationm Cp H Cp H (8.2.27)

where, Q = heat duty, kg/hr

m = mass flow rate inkg/h Cpwater = specific heat capacity, kJ/kg C Hevaporation = Enthaply heat of evaporation at respective temperature Water has a saturation temperature of at 32.98 C under 5 kPa pressure. From Appendix D.7, Chapter D.7.b, Q = 254 808 kJ/h. The amount of steam required is defined as

steam condensation steamcondensation

QQ m H m

H

(8.2.28)

where = heat tranfer efficiency Hcondensation = enthalpy heat of condensation, kJ/kg msteam = mass flow rate of steam, kg/hr Flow rate of steam required is 117.8 kg/h and amount of water evaporated is 103.18 kg/h. The volume of the vessel is defined by

V =60%

water

evap

m

r (8.2.29)

Where, mwater = mass flow rate of water evaporated, kg/h revap = evaporation ratem, taken as 50 kg H2O/h m3 Working volume is 60 % of the vessel size. The vessel dimension is taken as H = 4D. Refer to Appendix D.7, Chapter D.7.b for details. The amount of area required for heat exchange is also calculated from heat transferQ U A T .

From the calculation details Aheat transfer = 7.35 m2, while effective area of the dryer is 9.08 m2. Sufficient area is provided for heat transfer. Power requirement for dryer is defined as :

0.2P L D (8.2.30) where P, power in HP, L , length of dryer and D, diameter of dryer in feet.


CPD 3264 8-32

Calculation details in Appendix D.7, Chapter D.7.b. 8.2.6.3 T101 & T201 buffer tanks Both T101 Lactic acid buffer tank and T201 Ethanol buffer tank are designed based on storage for 1 day. This is to ensure sufficient amount of lactic acid and ethanol are in resource when either the lactic acid fermentor is under maintenance or if fresh ethanol supply is unavailable. Effective working volume is taken as 75 % for T101 and 80 % for T201. Height to diameter ratio is taken as 2:1. Calculation details can be seen in Appendix D.7.c. The material of construction of T101 is SS304 because of mild acidic conditions while Carbon Steel (CS) is used for T201 as only ethanol is present. 8.2.6.4 V301 & V401 mixing tanks V301 HCl Chitin mixing tank and V401 NaOH mixing tank are designed with the basis of a 5 minute residence time. This will ensure proper mixing of solids and liquids without an extensive period that would give significant effect on chitin reaction.

Effective working volume are taken as 75 % for V301 and V401. Height to diameter ratio is taken as 2:1. Impeller calculations are similar to R301, R302 and R401. The rotation speed is assumed as 0.5 rps. Refer to 8.2.1.2 for calculation details. Calculation details can be seen in Appendix D.7.d. The material of construction of V301 is SS316 because of the presence of chlorinated compounds. V401 on the other hand can be constructed with Carbon steel as concentrated NaOH renders corrosiveness with carbon steel. 8.2.7 Pipes and Pumps Pumps are required on all pipes that carry liquids because of pressure drop. In order to determine the power of the pump, first the pipe size has to be determined. Power of the pump is determined from the pressure drop, which increases if the pipe length is longer. Hence, a plant layout is established. The plant layout can be seen in Appendix D.8. Here, the layout has been employed that minimum crossing of pipes is required and sufficient space in between sections is available. The cross sectional view of the plant, also seen in Appendix D.8 shows that the equipments are separated onto 2 floors. Again this reduces space requirement and also piping. With the plant layout created, the pumps can be designed.


CPD 3264 8-33

8.2.7.1 Pressure Drop, Line Size and Pumps First of all we will give a small description of these topics. 8.2.7.1.1 Economic Pipe Diameter The most economic pipe diameter would be the one which gives the lowest operating costs. The Capital cost of pipe run increases with diameter while the pumping cost decreases with increasing diameter. The formula’s given below were basically generated by Genereaux (1937). [10] Economic pipe diameters for two most widely used materials are Carbon Steel Pipe:

0.52 -0.37, 260 d optimum G (8.2.31) Where G = mass flow rate in Kg/s = Density of fluid in Kg/cum Stainless steel pipe:

0.52 -0.37, 260 d optimum G (8.2.32)

8.2.7.1.2 Pressure Drop and Reynolds Number.

To calculate the pressure drop the pipe friction factor needs to be known. This is a function of Reynolds number.

For turbulent flow

The relationship proposed by Genereaux in clean commercial steel pipes was used.

10 1.84 0.16 1 4.84 4.13 10 P G d (8.2.33)

Where P = Pressure drop in kPa/m

= Viscosity in N s/sqr m d = Pipe diameter in mm G = Mass flow rate in Kg/s = Density of fluid in Kg/cum


CPD 3264 8-34

For Laminar flow Darcy equation was used to calculate the pressure drop in laminar flow regime[11,12].

9.81 . .

2

L uP f

d g

(8.2.34)

Where , 64 / Refriction factor f

P = Pressure drop in kPa/m 9.81 = Conversion factor for kPa/m L = Length in meter

1u = Velocity in m/s g = Acceleration due to gravity in m/sqr s d = pipe diameter in m

Calculations are done on a spreadsheet on a pump and line calculation sheet shown in Table D.8.1, Appendix D.8. The methods used will be illustrated by doing the detailed calculation of Pump P305 (Appendix D.8). A summary of pipe size can be seen on Table D.8.2. The choice of material for all piping is stainless steel, because most streams contain chlorinated compounds and mild acids. The pump house is made of mild steel while the pump rotor and shaft are constructed with high tensile steel. 8.3 Equipment Data Sheets Equipment data summary sheets are provided for quick reference for all the unit operations in the battery limits, while equipment data specification sheets contains more details for the basis of equipment ordering. These sheets are found in Appendix D.9.


CPD 3264 8-35

1 http://www.chemicalogic.com/co2tab/product_information.htm 2 C. Akerberg, et.al. Applied Microbiology and Biotechnology. 1998. 49 : 682 – 690 3 Conceptual Design of Chemical Processes , J.M. Douglas 4 Ke Liand B Cheng, Response Surface Optimization and Kinetics of Isolating Chitin from Pink Shrimp Shell waste, Taiwan 5 Sinnott “Coulson & Richardson Vol 6”, 2nd Edition p 478 6 Robert H. Perry, “Perry’s Chemical Engineers’ Handbook, 7th Edition”, Chapter 20 7 Coulson and Richardson, “Chemical Engineering Vol 6”, 2nd Edition, p 499 8 Robinson, R.K. Encyclopedia of Food Microbiology vol.2 2000 p.681 9 Bennett & Myers, Momentum, heat and Mass Transfer p 501 10 Sinnott, R.K, Coulson & Richardson Chemical Engineerig, Vol 6., 3rd Edition, Butterworth-Heinemann,1999 11 Warring, R.H, Pump: Selection, system and Application, 2nd Edition, Gulf publishing Co, 1984 12 Perry, R.H, Perry’s Chemical Engineer’s Handbook, 7th Edtion, McGraw-Hill Int’l ,1998


CPD 3264 9-1

Chapter 9 : Waste 9.1 Introduction and definition of waste Waste is an emotive topic and the reaction ‘Not In My Back Yard’ (NIMBY) is all too common. Public concerns and pressure groups are affecting company policy as in particular the chemical industry to strive to improve its image. Since, this project is proposed in Morocco, legislations from the European Community (EC) are employed. Although Morocco is not part of the EC, environmental laws from the EC are considered strict and acceptable for almost any country that do not have a specific law for the environment. So, what is waste? The Council of the European Communities issued the 1991 EC Directive 91/156, which defines waste as[1]:

1. Production or consumption residues not otherwise specified in this table 2. Off-specification products 3. Products whose date for appropriate use has expired 4. Materials spilled, lost or having undergone other mishap, including any materials,

equipment etc., contaminated as a result of the mishap 5. Materials contaminated or soiled as a result of planned actions – for example, residues

from cleaning operations, packing materials, containers 6. Unusable parts – for example, reject batteries, exhausted catalyst 7. Substances which no longer perform satisfactorily – for example, contaminated acids,

contaminated solvents, exhausted tempering salts 8. Residues of industrial processes – for example, slags, still bottoms 9. Residues from pollution abatement processes – for example, scrubber sludges, baghouse

dusts, spent filters 10. Machining or finishing residues – for example, lathe turning, mill scales 11. Residues from raw materials extraction and processing – for example, mining residues 12. Adulterated materials – for example – oils contaminated with PCBs 13. Any materials, substances or products whose use has been banned by law 14. Products for which the holder has no further use – for example, agricultural, household,

office, commercial and shop discards 15. Contaminated materials, substances or products resulting from remedial action with

respect to land 16. Any materials, substances or products which are not contained in the above categories

In this chapter, only direct waste are considered, that are waste is gaseous, liquids or solids produced directly from the process design plant. Based on the above criterias, all streams exiting the site that are not the main product (Chitosan), are considered waste streams. Waste can generally be treated or discarded directly into the environment. If the waste is hazardous, there are five primary methods for management:

1. Recycling materials off-site or to other on-site processes 2. Reuse as fuel 3. Incineration 4. Physical, chemical, and biological treatment of aqueous wastes 5. Land treatment and disposal


CPD 3264 9-2

9.2 Identifying and classifying waste The waste streams based on the PFS (Fig 5.2.1) are: a. Stream 112a + 112b, 301 & 311 (CO2 gas streams)

These streams are the gaseous waste streams from reactors R101 a/b, R301a/b and R302. The only product in this stream is CO2; a greenhouse gas. The total amount of CO2 produced is 573 tonnes/year.

Table 9.2.1: CO2 gas emission

Stream No. Amount (tonnes/day)

Effects on environment Notes

112a + 112b 0.08 Greenhouse gas – global warming Released into environment by stack 301 1.51

311 0.12

CO2 gas is generally not toxic nor hazardous, hence treatment for this component is not needed. However, emission should be controlled, based on agreements of the Kyoto Treaty to reduce the amount of greenhouse gases. The effluent is released into the environment at an average of 30 C. Dispersion is governed by permissible limits on ground level concentrations. The design of stacks therefore depends on topography, meterology and contaminant properties. Models like the Gaussian plume model can be carried out to determine the concentration of CO2 in the air, x distance from the stack.

The program of Gaussian plume model can be found on

http://www.shodor.org/master/environmental/air/plume/

The stack height can be determined, based on the assumption that:

a. Stack diameter of 1 meter b. Temperature of gas release is averaged at 30 C and ambient temperature is 25 C. c. The three streams are connected and dispersed in one stack.

From the mass balances, 19.8 g/s of CO2 is released, and with a stack diameter of 1 meter, the exit velocity of gas is 0.014 m/s. Detailed calculation on exit velocity is in Appendix E.

Based on the limits of MAC for CO2 at 9000 mg/m3, at any point downstream of the stack, concentrations should not exceed this value.


CPD 3264 9-3

Table 9.2.2: CO2 concentration at ground level downstream of wind direction

Different wind velocity are tested, with wind velocity of 1 m/s being the worst case possible. Conditions of the flow are determined from Pascuill stability classification system[2]. From the table, it can be concluded that at any stack high, the concentrations of CO2 will always be below 9 106 mmg/m3 as the amount released is relatively small. Hence, for structural wise, the stack of 15 m in height is taken.

b. Stream 210 – Benzoic acid slurry The main components in this stream are Benzoic acid, ethanol and water. Temperature of the stream is about 87 C.

Table 9.2.3 Stream 210 main components Component Amount

(tonnes/day) Effects on environment Notes

Benzoic acid

0.30 Acidic Harmful to living organisms in large quantities Preservative – prevents microorganism growth

Partially solids

Ethanol 0.20 Flammable material Toxic in large amounts

Liquid

Water 0.10 None Aqueous This stream has potential as raw materials on other plants. Hence, it is suggested that the stream be further purified off-site to obtain separately benzoic acid and the solvent mixture of ethanol and water. The solvent mixture can be reused on-site and the benzoic acid sold back to the shrimp industry as preservative. In order to separate benzoic acid, precipitation or crystallization of the remaining benzoic acid dissolved in the solvent is required. This can be done in a crystallizer. The amount of benzoic acid needed to be crystallized is 60 kg/day. (Calculation details in Appendix E)

0 0.5 0.8 1.5 5 10 25 50 100

1 Stable 10 0 16227 12331 5569 1151 540 245 151 995 Neutral 10 0 1279 605 221 37 15 5 2 1

10 Unstable 10 0 133 53 16 2 0 0 0 01 Stable 15 0 4532 6600 4486 1083 519 238 148 965 Neutral 15 0 1136 569 215 37 15 5 2 1

10 Unstable 15 0 131 53 16 2 0 0 0 01 Stable 20 0 760 2751 3314 994 491 229 143 935 Neutral 20 0 963 523 208 37 15 5 2 1

10 Unstable 20 0 127 52 16 2 0 0 0 0

VelocityEffective

Stack Height

Condition Concentrations (mmg/m3) at ground level distance (m) from stack


CPD 3264 9-4

c. Stream 305 – Protein Hydrolysate This stream contains the liquid fraction of the enzymatic demineralization and deproteinization reaction plus some solids lost from the filter. The main components are H20, lactic acid, proteins, carbohydrates, calcium lactate, lipids plus asthaxanthin and the unused fermentation broth (glucose and ammonium sulphate). There are trace elements of dissolved CO2, ethanol from the extraction of benzoic acid and sulphuric acid. Some chitin as well as chitosan are also lost in this stream.

Table 9.2.4 Stream 305 main components Component Amount


H20 65.7 None Aqueous

Lactic acid 1.17 Acidic Liquid Proteins, Glucose, liqids and asthaxanthin

3.10 Eutrophication if released into rivers and lakes

Aqueous suspension

Calcium lactate 7.60 None Aqueous H2SO4 0.34 Acidic

Corrosive Aqueous

Trace elements Dissolved CO2, ethanol and fermentation broth

0.17 Small quantities – insignificant effect

Aqueous

Chitin and chitosan 0.03 None Solids The pH of the stream is approximately 5.5. The pH is buffered or controlled in fermentor and by the production of calcium lactate that is slightly basic. Part of the stream components can be separated. The aqueous suspension and solids can be separated and used as farm feedstock. The protein hydrolysate is a good source of protein and the pigment asthaxanthin makes a good feedstock for salmon fishes, as the pigment can give the salmon fish the redness it requires. Separation can be done in a centrifuge or cyclone. Since stream 413 is highly alkaline, it is advised to neutralize this stream by combining the streams together.


CPD 3264 9-5

d. Stream 315 - Chemical purification waste stream

Table 9.2.5: Stream 315 main components Component Amount

(tonnes/day)Effects on environment Notes


HCl 0.52 Acidic Corrosive

Aqueous

CaCl2 0.40 Toxic Aqueous Calcium lactate 0.20 None Aqueous Trace elements Lactic acid, H2SO4, protein, lipids, glucose, CO2


Aqueous suspension

Chitin, Chitosan 0.03 None Solids The main problem in this stream are the acidity caused by HCl and the toxicity by CaCl2. The pH of the stream is 0.50 (Appendix E). As with Stream 305, this stream can be neutralized with Stream 413. CaCl2 can be precipitated by addition of NH3, separated and sold as a raw material for other industries, e.g. ice melting and water treatment. However, this may not be economical as CaCl2 is not an expensive commodity. Disposing CaCl2 into the sea directly may not be much of a problem as well, as the sea is filled with chloride and it will take a significant amount of chloride ions to cause a huge imbalance in the ecosystem. e. Stream 413 – NaOH waste stream

Table 9.2.6: Stream 413 main components Component Amount



NaOH 30.26 Alkaline Corrosive

Aqueous

Acetic acid 0.46 Acidic Aqueous Proteins 1.95 None Aqueous suspension Trace elements NaCl, glucose, chitosan, CaCl2, calcium lactate


Aqueous + solids

Main problem is alkalinity of the stream. It has been suggested that streams 305 and 315 are combined with this stream to reduce the alkalinity and to solve the problem of disposing acids.


CPD 3264 9-6

After combining the streams, the pH still remains 14 (Calculation details in Appendix E). Hence, it is suggested that the stream is neutralized, diluted or recovered. With such a large amount of alkaline materials, it would not be suggested to neutralize nor dilute the stream as it will require a huge amount of acids or H2O and this would be uneconomical. The option chosen is to recovery NaOH. Few methods that can be used are:

i. Electrolysis ii. Electrochemical membrane

After separation, the NaOH is recycled while the rest will be disposed as a waste stream. The waste stream does not contain significant amount of hazardous, flammable or toxic materials. f. Stream 415 (H2O)

Table 9.2.7 : Stream 415 Component Amount


H20 2.5 None Water vapour This stream only contains water. It can be released directly into the environment. This stream can be combined with discharge stream streams and released through the stack. Figure 9.2.1 shows the summary of the waste streams.

Figure 9.2.1: Summary of Waste streams

CO2 and air

415

311

301

112a + 112b

210 Crystallizer

Ethanol & H2O recovery

Benzoic acid crystals

Dispersed by stack (15 m)

On-site Off-site

305 Centrifuge/

cyclone

Protein, carbohydrates, lipids, asthaxanthin, chitin & chitosan (farm feedstock)

315H2SO4, calcium lactate, trace elements, H2O

HCl, H2O, CaCl2, Ca lactate, trace elements

413 Neutralizing vessel

NaOH recovery

NaOH, H2O

Waste water for discharge

NaOH, H2O, acetic acid, proteins, trace elements

H2O

CO2 and air

415

311

301

112a + 112b

210 Crystallizer

Ethanol & H2O recovery

Benzoic acid crystals

Dispersed by stack (15 m)

On-site Off-site

305 Centrifuge/

cyclone

Protein, carbohydrates, lipids, asthaxanthin, chitin & chitosan (farm feedstock)

315H2SO4, calcium lactate, trace elements, H2O

HCl, H2O, CaCl2, Ca lactate, trace elements

413 Neutralizing vessel

NaOH recovery

NaOH, H2O

Waste water for discharge

NaOH, H2O, acetic acid, proteins, trace elements

H2O


CPD 3264 9-7

1 R.Bahu, B. Crittenden, J. O’Hara, Management of Process Industry Waste,1997 2 H.J. Pasman, S.M. Lemkowitz, Chemical Risk Management, TU Delft 2001


CPD 3264 10-1

Chapter 10 : Process Safety

Safety and reliability in the design of plant initially relies upon the application of various codes of practice, or design codes and standards. These represent the accumulation of knowledge and experience of both individual experts and the industry as a whole. Such application is usually backed up by the experience of the engineers involved, who might well have been previously concerned with the design, commissioning or operation of similar plant.

However, it is considered that although codes of practice are extremely valuable, it is important to supplement them with an imaginative anticipation of deviations which might occur because of, for example, equipment malfunction or operator error. In addition, most companies will admit to the fact that for a new plant, design personnel are under pressure to keep the project on schedule. This pressure always results in errors and oversights. The Hazop Study (HAZOP) and the DOW Fire and Explosion Index (FEI) are opportunities to correct these before such changes become too expensive, or 'impossible' to accomplish.

Although no statistics are available to verify the claim, it is believed that the HAZOP and FEI methodologies are perhaps the most widely used aids to loss prevention. The reason for this can most probably be summarized as follows:

They are easy to learn.

They can be easily adapted to almost all the operations that are carried out within process industries.

No special level of academic qualification is required. One does not need to be a university graduate to participate in a study.

10.1 HAZOP Hazard & Operability (HAZOP) Analysis is recognized as one of the most powerful tools for identifying potential accidents in processes involving hazardous chemicals, and for developing a course of action to minimize the risks of these accidents. It may also be used to enhance process efficiency In this plant, the critical equipment that require the most attention are R401 Deacetylation reactor , because of its high operating temperature and C201 Ethanol Evaporator where ethanol a flammable substance is present. 10.1.1 R401 Deacetylation Main materials in: Chitin, NaOH Guide Word Deviation Possible Causes Consequences Action Required Not, No No Flow 1) No NaOH

available in storage tank

2) NaOH pump

fails (motor fault, loss of drive, impeller corroded away etc.)

1. Chitin production rather than Chitosan.

2. Same as (1).

1 Ensure good communication with storage tank operator. Install low level alarm at storage tank LIC

2 As for 1.


CPD 3264 10-2

3) Line blockage,

isolation, valve closed in error or LCV fails shut.

4) Line fracture 5) Conveyer not

working ( shrimps flow problem)

3. As for (1),

pump overheats

4. As for (1),

NaOH discharged at the site. Floor becomes slippery and very hazardous for labor.

5. As for 1. No

conversion of Chitin to Chitosan. Loss of caustic

3 Install kickback on

pump. Check design of pump strainers

4 Institute regular

patrolling and inspection of transfer line. Install additional line

5 Install additional

conveyer.

More More Flow 6) LCV fails open or LCV bypass in error

6. Reactor overfills. Incomplete deacetylation of Chitin

6 Institute locking of f procedure for LCV bypass when not in use

More Temperature 7) Thermal

expansion in an isolated valved section due to fire or strong sunlight.

8) High

temperature of Incoming NaOH.

7. Line fracture or flange leak. High pressure in transfer line and reactor. Product might get pale.

8. High Reactor temperature. Product may get pale.

7 Install thermal expansion relief on valved section (relief discharge route to be decided later in the study.

8 Install a TI on

NaOH line.

Less Less Flow 9) Leaking flange or valve

9 Low rate of production

9 Covered by 3.

As well as Acids, and other impurities

10) Disturbance upstream in reactors or in filtration.

10. Increased rate of corrosion of reactor and lines. Impure product specification. Lower rate of reaction.

10 Check suitability of materials on construction.


CPD 3264 10-3

Part of Higher concentration of protein and other solids.

11) Incomplete demineralization and deprotenization of shrimp shells.

11. Impure product specification. Lower rate of reaction.

11 Check that the design of reactor and associated equipment will cope with sudden ingress of these impurities.

Other than Maintenance 12) Equipment

failure flange leak , conveyer failure etc.

12. Line closed. Processing stopped.

12 Install bypass of pumps and lines. Arrangement of additional conveyer etc.

10.1.2 C201 Ethanol Evaporator Main materials in : Ethanol, water, Benzoic acid Guide Word Deviation Possible Causes Consequences Action Required Not/No No flow 1) No feed to

Distillation Column.

2) Pump fails

(motor fault, loss of drive, impeller corroded away etc.)

3) Line blockage,

isolation, valve closed in error or LCV fails shut.

4) Line fracture

1. Nothing to separate. Loss of heat.

2. As for 1 3. As for 1. Pump

heat up. 4. Ethanol water

mixture discharged into the factory area.

1 1 Check ethanol flowing in. Ensure good communication with Ethanol water storage opearator. Install low level alarm distillation column LIC.

2 As for 1. 3 Install kickback

on pump. Check design of pump strainers

4 Institute regular

patrolling and inspection of transfer line

More More Flow 5) LCV fails open

5. Not perfect

separation. Ethanol losses from the bottom.

5 Install high level alarm on LIC and check sizing of relief opposite liquid over-filling.


CPD 3264 10-4

More Temperature 6) Thermal expansion in an isolated valved section due to fire or strong sunlight.

6. Line fracture or flange leak. More water going from top. Disturbance in other units.

6 Install thermal expansion relief on valved section.

Less Less Flow 7) Leaking flange or valve

7. Material loss in the field

7 Covered by 4. Check line, flange ratings and reduce stroking speed of LCV if necessary.

Part of High water or

ethanol concentration in stream

8) Problem upstream in make up ethanol flow to extractor.

8. Lower or high extraction efficiency because of more water or lower content in top product.

8 Covered in 4 and 7. Check that the design of distillation column will cope with sudden ingress of ethanol and water.


CPD 3264 10-5

10.2 Dow Fire and Explosion Index (FEI) The Fire and Explosion Risk Analysis Program is a realistic evaluation of the realistic fire, explosion, and reactivity potential of process equipment and its contents. The evaluation of the chitin and chitosan production plant is carried out. The calculation is set out on the special form shown in Table 10.2.2. Notes on the decision taken and the factors used are given below. Material factor: for ethanol, from Dow Guide, MF = 16.0 Note: Ethanol is considered the most flammable/explosive material on the plant. From the Dow Guide, ethanol’s properties are given as below: Table 10.2.1 Ethanol properties for FEI Compound MF Hc

BTU/lb. 10-3

NFPA Classification Flash Point oF

Boiling Point oF Nh Nf Nr

Ethanol 16 11.5 0 3 0 55 173 Units: Units that handle ethanol are the S201 Benzoic acid extractor and C201 Ethanol evaporator. 1. General process hazards:

A. No reactions occur. Ethanol is used as a solvent and recovered from the solute. Factor = 0.0

B. No reactions occur. Not applicable. C. Storage of ethanol with Nf = 3 receives a penalty of 0.85. D. Plant is located indoors. Flammable liquid ethanol handled at temperatures above its

flash point in an enclosed area receives a penalty of 0.30. E. Adequate access would be provided, factor = 0.0. F. Adequate drainage would be provided, factor = 0.0.

2. Special process hazards A. Ethanol has a Nh = 0, meaning there is no risk of toxicity. Factor = 0.0 B. Not applicable C. Operation in flash tank has ethanol always within flammable limits, factor = 0.8. D. Not applicable E. Operating pressures are at atmospheric conditions. Not applicable. F. Not applicable G. Ethanol is present in a circulation at the pretreatment of the plant to remove benzoic acid.

Amount present, 2200 lbs.

Heat of combustion = 11.5 103 BTU/lb Potential energy release = 2200 (11.5 103) = 2.53 107 BTU Which is too small to register from the Dow Guide, factor = 0.0.

H. Corrosion resistant materials of construction would be specified, but external corrosion is possible, allow minimum factor = 0.1.

I. Welded joints would be used on ethanol service and mechanical seals on pumps. Use minimum factor as full equipment details are not known at the flowsheet stage, factor = 0.1.

J. Not applicable K. Not applicable L. Ethanol is not in contact with heavy duty compressors and pumps. Factor = 0.0.

The index works out at 86. The Unit Hazard Factor (F3) is calculated as 5.38, which is within the normal range of 1 to 8. The hazards are of normal operating conditions. The measures taken should be


CPD 3264 10-6

implemented to keep the plant within safe operation. Proper drainage and accessibility should be provided to avoid concentrating the dangers or increasing the probability of an accident occurring. Table 10.2.2 Fire and Explosion Index form

FIRE AND EXPLOSION INDEX

DATETangier, Morocco 28-Nov-01

PLANT PROCESS UNIT EVALUATED BY REVIEWED BYChitin and Chitosan whole plant

MATERIALS IN PROCESS UNITEthanol, water, benzoic acid, shrimp shellsSTATE OF OPERATION BASIC MATERIAL(S) FOR MATERIAL FACTOR[ ] START UP [ ] SHUT DOWN [x] NORMAL OPERATION Ethanol

MATERIAL FACTOR 16

1. GENERAL PROCESS HAZARDS PENALTYUSED

BASE FACTOR 1.00 1.00A. EXOTHERMIC CHEMICAL REACTIONS (FACTOR 0.30 TO 1.25) 0.00B. ENDOTHERMIC PROCESS (FACTOR 0.20 TO 0.40) 0.00C. MATERIAL HANDLING AND TRANSFER (FACTOR 0.25 TO 1.05) 0.85D. ENCLOSED OR INDOOR PROCESS UNITS (FACTOR 0.25 TO 0.90) 0.30E. ACCESS 0.35 0.00F. DRAINAGE AND SPILL CONTROL (FACTOR 0.25 TO 0.50) 0.00

GENERAL PROCESS HAZARDS FACTOR (F1) 2.15

2. SPECIAL PROCESS HAZARDS

BASE FACTOR 1.00 1.00A. TOXIC MATERIALS (FACTOR 0.20 TO 0.80) 0.00B. SUB-ATMOSPHERIC PRESSURE (<500 mmHg) 0.50 0.00

INERTED

NOT INERTED

1. TANK FARMS STORAGE FLAMMABLE LIQUIDS 0.50 0.50 2. PROCESS UPSET OR PURGE FAILURE 0.30 0.00 3. ALWAYS IN FLAMMABLE RANGE 0.80 0.80D. DUST EXPLOSION (FACTOR 0.25 TO 2.00) 0.00E. PRESSURE OPERATING PRESSURE: 1 atm 0.00 RELIEF SETTING: 1.2 atm

F. LOW TEMPERATURE (FACTOR 0.20 TO 0.30) 0.00G. QUALITY OF FLAMMABLE/UNSTABLE MATERIAL:

QUANTITY: 2200 lb HC 11.5 x 103 BTU/lb

1. LIQUIDS, GASES AnD REACTIVE MATERIALS IN PROCESS 0.00 2. LIQUIDS OR GASES IN STORAGE 0.00 3. COMBUSTIBLE SOLIDS IN STORAGE DUST IN PROCESS 0.00H. CORROSION AND EROSION (FACTOR 0.10 TO 0.75) 0.10I. LEAKAGE-JOINTS AND PACKING (FACTOR 0.10 TO 1.50) 0.10J. USE OF FIRED HEATERS 0.00K. HOT OIL HEAT EXCHANGE SYSTEM (FACTOR 0.15 TO 1.50) 0.00L. ROTATING EQUIPMENT 0.50 0.00

SPECIAL PROCESS HAZARDS FACTOR (F2) 2.50

UNIT HAZARD FACTOR (F1 X F2 = F3) 5.38

FIRE AND EXPLOSION INDEX (F3 X MF-F AND EI) 86

C. OPERATION IN OR NEAR FLAMMABLE RANGE

LOCATION

MATERIAL AND PROCESS

PENALTY


CPD 3264 11-1

Chapter 11 : Economy

All Chemical plants are built to make profit, and an estimate of the investment and production costs are necessary before the economic evaluation of the process can be done. Following tables contains estimation of investment costs, production costs, and economic evaluation. Investment costs are evaluated utilizing Lang factorial method. Table 11.1 Capital Investment CostsCAPITAL INVESTMENT COSTS EQUIPMENT COSTS @ 2001[1,2,3,4] €Crusher and Grinder Filters Reactors Buffer Tanks Extractor Dryer Evaporator Heat Exchangers Mixers Pumps Conveyers

137,100205,600485,900

67,4007,400

102,800274,100

22,60022,900

280,900118,900

PURCHASE EQUIPMENT COSTS @ 2001 1,725,600 Total Direct Capital Costs, million € @ 2001 -Lang Factor, Process type “Fluids-Solids” : 3.15 Indirect Capital Costs, million € @ 2001 -Lang Factor, Process type “Fluids-Solids” : 0.40 FIXED CAPITAL COSTS, million € @ 2001 -Total Direct + Indirect Capital Costs -Lang Factor, Process Type “Fluids : 1.40

5.436

2.174

7.610

Table 11.2 Total Investment Costs

TOTAL INVESTMENT COSTS million € TOTAL INVESTMENT COSTS, million € @ 2001 -Fixed Capital Capital Costs divided by : 0.80 License Costs, million € @ 2001 -Total Investment Costs multiplied by : 0.14 WORKING CAPITAL COSTS, million € @ 2001 -Total Investment Costs multiplied by : 0.06

9.512

1.332

0.571

The values given in the above tables were converted to be used in 2001 by applying index correction of 7 % per year. The following conversion rates were used throughout this economic evaluation. 1 US $ = 1.085 € 1 UK £ = 1.612 € 1 € = 2.20371NLG

Plant Life = 15 years Operating hours per year = 8040 hrs


CPD 3264 11-2

PRODUCTION (OPERATION COSTS)

Table 11.3 Raw Material Cost RAW MATERIALS FROM PFS-MATERIAL BALANCES

IN/OUT Name Stream No kg/hr Tons/a Price €/ton[5]

million € per annum

IN

OUT

Shrimp Shells Glucose Ammonium Sulphate Ethanol HCL NaOH Process Water

201 102 107 213 307 401

102,107,213 307,401,411

1250 365.7 21.9 10.3 34.2 1262

6,000.6

10,050.0 2,940.2

176.2 82.7

274.7 10,147.1

482,447.8

- 453.8 25.6

1,064.1 198.3 360.8

0.7

-1.3340.0050.0880.0543.6610.033

Total IN 71,915.8 5.175 CO2 Benzoic Acid stream Water (with hydrolysate) Protein hydrolysate Filter2 waste stream Filter 3 waste stream Dryer Gas Chitosan

112,301,311

209 305 305 315 413 415 417

71.3 24.9

2,523.1 765.0

1904.8 3,455.6

103.2 96.8

573.6

200.23 20,285.4 6,151.0

15,314.5 27,783.2

829.6 778.2

TOTAL OUT 71,915.8 5.175

IN-OUT = RAW MATERIAL COST 5.175

Table 11.4 Utilities

UTILITIES FORM PFS

IN/OUT Name kg/hr Tons/annum € /ton € per annum

IN MP Steam LP Steam Cooling Water Chilled Water

88 184

11,799 13,021

705.3 1,479.1

98,864.9 104,688.0

31.613 27.227 0.045 0.907

9,601.040,270.54,304.8

95,010.7 kW kWh/annum € / kWh

Electricity 39 364,420.0 0.046 16,801.3

TOTAL = UTILITIES 165988.3

Electricity : kW(shaft)/0.85 required from the net LABOUR COSTS Table 11.5 Total Operating Labour

COST DATA RESULTS

Number of Operators/Shift Number of Shifts Number of Operators in total Cost per Operator € @2001

125

6049089.4

Total Operating Labour million € /a @ 2001 2.945


CPD 3264 11-3

Table 11.6 Production Cost SUMMARY OF PRODUCTION COSTS

Variable Costs Costs, million € per annum % Production Costs 1 2 3 4

Raw Materials Miscellaneous Materials Utilities Shipping and Packaging

5.175 0.057 0.166

31.7130.3501.017

Sub-total A

5.398 33.080

Fixed Costs

5 6 7 8 9 10 11 12 13

Maintenance Operating Labor Laboratory Costs Supervision Plant Overheads Capital Charges Insurance Local Taxes Royalties

0.571 2.945 0.633 0.589 1.473 1.141 0.076 0.152 0.076

3.49718.0483.8803.6109.0246.9950.4660.9330.466

Sub-total B

7.657 46.920

Direct Production Costs A + B 13.055 80.000

13 14 15

Sales Expense General Overheads Research and development

3.264 20.000

Sub-total C

3.264 20.000

Annual Production Cost= A + B + C

16.319

Production Costs Dfl/ton = cos

Annual production t

Annual production rate=21.0


CPD 3264 11-4

GROSS INCOME, CASH FLOW, ECONOMIC CRITERIA Table 11.7 Pay-Out-Time ITEM

UNIT RESULT REMARKS

Chitosan–Sales Sales Price

Tons/annum € / ton

778.24 453.78

=A

Hydrolysate-Sale Sales price

Tons/annum € / ton

6,151.01 0.48

GROSS INCOME Production Costs Cash Flow

million € per annum million € per annum million € per annum

356.08

16.32

339.76

CAPITAL INVESTMENT

million €

9.51

= B

PAY-OUT-TIME (POT)

Years

0.028

=B/A

Total Capital Investment = 9.51 million € The following assumptions were made

1. Constant Product and Raw materials costs. 2. Constant Sales Price of Products 3. Total product manufactured each is sold. 4. Construction in Two years

Year 1 = 4.76 million € (Design + Construction) Year 2 = 4.76 million € (Construction + Working Capital)

Discounted Cash flow (time value of money): The Net present worth is given by

1

( ) ( )

(1 )

(int ) /100

(1 )

n

n t

nn

Estimated net cash flow in year n NFWNet present worth NPW

r

of cash flow in year n

Where r is the discount rate erest rate per cent and

NFWTotal NPW of the project

r

t

, life of project years

Discount rate chosen = 13 % (as it is roughly equal to the current interest rate that the money could earn if invested.) NPW (at 13 %) = 1711.61 million € For detailed calculation see Appendix F.


CPD 3264 11-5

Rate of Return: The rate of return provides a way of measuring the performance of the capital invested. ROR is given by

100

5086.97

9.51

15

5086.97 100

9.51 15

Cumulative net cash flow at the end of projectROR per cent

Life of project original investment

Cumulative income

Investment

Life of project

ROR p

3565.1 %er cent

For detailed calculation see Appendix F. Discounted Cash Flow Rate of Return (DCFRR) Discounted cash flow analysis (time value of money) is sensitive to interest rate chosen. In DCFRR we calculate NPW, we find the interest rate at which the cumulative net present worth at the end of project is zero. This particular rate is a measure of the maximum rate that the project could pay and still break even by the end of the project life.

0(1 )1

n t NFWnrn

0'(1 )1

' - - 751 %

n t NFWnrn

The value of r found by trial and error calculation is

For detailed Calculation see appendix F Discussion: The production and sales cost of the product are Production cost per kg = 21 € Sales cost per kg = 453 € By comparing these values, it is clear the margin per kg of product is really huge. In fact this is reason for such, ROR = 3651 % DCFROR = 751 % POT = 0.028 year Values. The margin is so high that it pays off the total capital investment within the few months of running the plant. This is also shown by the project cash flow diagram given below. The break-even point is almost at years showing that as soon as the plant starts it pays off the total capital investment.


CPD 3264 11-6

Project Cash Flow Diagram

-1000

0

1000

2000

3000

4000

5000

6000

0 2 4 6 8 10 12 14 16

Time, years

Cu

mu

lati

ve c

ash

flo

w, m

illio

n €

NFW

NPW at 15 %

NPW at 100 %

NPW at 500 %

NPW at 751 %

Fig 11.1 Project Cash Flow Diagram

Cost Review: Table 11.8 Purchase Equipment Cost

CAPITAL INVESTMENT COSTS % PEC EQUIPMENT COSTS @ 2001 € Crusher and Grinder 137,100 7.94 Filters 205,600 11.91 Reactors 485,900 28.16 Buffer Tanks Extractor Dryer Evaporator Heat Exchangers Mixers Pumps Conveyers

67,400 7,400

102,800 274,100

22,600 22,900

280,900 118,900

3.90 0.42 5.96

15.88 1.31 1.33

16.28 6.89

PURCHASE EQUIPMENT COSTS @ 2001 1,725,600 100 By review the above table, we found that there are few components which contributes more to the purchase equipment costs. Namely these are reactors, evaporator, pumps, and filters. Reactors and filters are the main components and a slight change in their efficiency can have quite adverse effect on the process. Besides this costs accounts for three filters and three reactors so the cost per components is not much. All the pumps used in this process are diaphragm. These pumps are costly but can handle solids and low flow rates. Centrifugal pumps could be another choice for cost reasons but will need more operating costs. Same is the case with evaporator, if chose for typical flash drum then the losses of ethanol would be higher. This process has very high margin, therefore the effect of reducing these cost is approximately none.


CPD 3264 11-7

Sensitivities: This process has a very high margin therefore +/- 10 % variation in any cost doesn’t effect the process at all. Even if the production costs multiplies to double it doesn’t make much effect on the economics. So the process is insensitive to small variations. Product cost per Kg = 21 € Sale Price Chitosan = 453 €


CPD 3264 11-8

1 Sinnott, R.K, Coulson & Richardson Chemical Engineerig, Vol 6., 3rd Edition, Butterworth-Heinemann,1999 2 Timmerhaus, K.D, Plant Design and Economics for Chemical Engineers, 4th Edition, McGraw-Hill Intl, 1991 3 www.process-heating.com 4 www.brewtechinc.com 5 Perry, R.H, Perry’s Chemical Engineer’s Handbook, 7th Edtion, McGraw-Hill Int’l ,1998


CPD 3264 12-1

Chapter 12 Conclusions and Recommendations On the whole, the process has been a success in producing a good economic evaluation. Economically, the plant has a cash flow of € 340 million and a POT of 10 days. Furthermore, this process is seen as a green process as it utilizes less hazardous and toxic chemicals than the current chitin/chitosan plants in operation. The use of enzymatic reactions also allows the recovery of the protein hydrolysate portion of the shrimp shells, which can be sold as animal feed, e.g. salmon industry. The recovered protein hydrolysate also contains a small fraction of very expensive component asthaxanthin, which when purified can be of great value. However, the plant also has its weaknesses. There has been a slight problem with the use of concentrated NaOH, as the waste stream produced from the deacetylation reaction shows that the stream is highly caustic. In a chemical process chitosan plant, there is the presence of concentrated HCl (substituted by lactic acid in this process) which can be used to neutralize this stream, but in this plant design, only mild HCl is used and hence, NaOH needs to be recovered which may be non-economical. Hence it may be suggested that if concentrated NaOH is used, concentrated HCl should also be used. So it is not a good idea to combine half the process done enzymatically (production of chitin) and half chemically (production of chitosan). The reliability of the design may be of an issue. Data were collected from journals and reaction kinetics are based on lab scaled experiments. Furthermore the whole process is a combination of a few individual lab experiments, and this may result inaccuracy. Scaling up for R301 a/b, R302 and R401 with reaction kinetics of lab scaled may produce some errors, as behaviour of flow and contact time may differ. In order to improve the design, pilot plant studies should be done to investigate the reactions. It should also be pointed out that the basis of shrimp composition in this design is based on an average of reported findings. This basis alone defines the design of the process. Hence, careful investigation on the shrimp shell composition needs to be done before attempting to make this plant design a reality. An alternative way of doing the enzymatic deproteinization and demineralization is by combining the lactic acid fermentation and the deproteinization/demineralization step into one unit operation. However, by doing so, the process becomes semi-batch. There would be a need to clean the fermentor/lactic acid reactor and hence storage is required before and after this reactor. However by doing so, there is the benefit of reducing the amount of complex unit operations on site, such as microfilters. Finally it may be said that further investigation on information, i.e. reaction kinetics and shrimp shell compositions should be done to make this plant design more reliable. Optimization of the operating conditions can also be done on varying the temperatures and pressures of the reactors if proper experimental results can be obtained.


CPD 3264 2-4

2.2 Creative Decision Making Process

Figure 2.2.1 Decision Tree

Selected Process : Enzymatic Deprotenization by inherently present enzymes in shrimp shells

: Chemical Demineralization by Lactic Acid and purfication by HCL

: Chemical Deacetylation under autoclaving conditions

Chemical

Not environmental

friendly

Chitin and Chitosan ProductionShrimp Shells

Process

Harsh condition

Autoclavemedium

condition

Enzymatic

still in research

state

Enzymatic + Chemical

Stop Stop

Stop

Lactic acid

Acetic acid

Strong Chemical

HCL

Deacetylation

Chemical

Enzymatic Deprotenization

Demineralization

Enzyme addition

Utilizing shell

enzymes

Stop Stop As purification step after lactic acid

Stop

In-situ fermentation

Sep. fermentation

still in research

state

Stop

Enzymatic

Selected Process : Enzymatic Deprotenization by inherently present enzymes in shrimp shells

: Chemical Demineralization by Lactic Acid and purfication by HCL

: Chemical Deacetylation under autoclaving conditions

Chemical

Not environmental

friendly

Chitin and Chitosan ProductionShrimp ShellsShrimp Shells

Process

Harsh condition

Autoclavemedium

condition

Enzymatic

still in research

state

Enzymatic + Chemical

StopStopStop StopStopStop

StopStopStop

Lactic acid

Acetic acid

Strong Chemical

HCL

Deacetylation

Chemical

Enzymatic Deprotenization

Demineralization

Enzyme addition

Utilizing shell

enzymes

StopStopStop StopStopStop As purification step after lactic acid

StopStopStop

In-situ fermentation

Sep. fermentation

still in research

state

StopStopStop

Enzymatic


CPD 3264 2-5

Figure 2.2.1 continued

Selected Process

Design Simulation

Aspen : Chemical

Matlab : Fermentation

Super pro : Fermentation

Pretreatment DeacetylationFermentation Deprotenization

Demineralization

Benzoic acid removal by solvent

Size reduction

Solvent recovery

Basis : Shrimp Shell Composition

Heat integration

Control

Economics Integration

Selected Process

Design Simulation

Aspen : Chemical



SimulationSimulation

Aspen : Chemical



Pretreatment DeacetylationFermentation Deprotenization

Demineralization

Benzoic acid removal by solvent

Size reduction

Solvent recovery

Basis : Shrimp Shell CompositionBasis : Shrimp Shell Composition

Heat integration

Control

Economics Integration

Heat integration

Control

Economics IntegrationIntegration

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