maleic anhydride
DESCRIPTION
a small project on maleic anhydrideTRANSCRIPT
MANUFACTURE OF MALEIC ANHYDRIDE
(100 TON PER DAY)
Submitted
In partial fulfillment for the award of the degree of
BACHELOR OF TECHNOLOGY
IN
CHEMICAL ENGINEERING
By
G. SAI SOUNDARYA
ROLL NO.1008-11-802-032
Under the esteemed guidance of
Prof. Dr V. RAMESH KUMAR
Department of Chemical Engineering
University College of Technology
Osmania University, HYD – 500007 (T.S)
University College of TechnologyOsmania University
CERTIFICATE
This is to certify that thesis entitled “Manufacture Of Maleic Anhydride” being
submitted by Ms.G.Sai Soundarya bearing the Roll No: 1008-11-802-032 , for the
award of the degree of Bachelor of Technology in Chemical Engineering at University
College of Technology, Osmania University, is a record of bonafide work carried out by
her independently during the academic year 2014-15.
Signature of guide
Signature of Head of the Department Signature of principal
Date of viva-voce examination
Signature of internal examiner Signature of external examiner
DECLARATION
I hereby declare that this is the bonafied record of project work ,
entitled “MANUFACTURE OF MALEIC ANHYDRIDE” done under the
supervision of Prof. V. Ramesh Kumar, as a part of partial fulfillment of the
requirements for the award of B. Tech. degree in Chemical Engineering at
College of Technology, Osmania University, Hyderabad.
To the best of my knowledge, the matter embodied in the report has
not been submitted to any other University/Institute for the award of any
Degree/Diploma.
Date:
G.SAI SOUNDARYA
1008-11-802-032
ACKNOWLEDGEMENT
I am very much indebted to Dr V.Ramesh Kumar, professor of
chemical engineering, College of Technology, Osmania University, Hyderabad
for his invaluable suggestions, constructive advice, and guidance throughout
the project work. He was very supportive throughout the project and was
always ready to help.
I am also thankful to all the staff members of College of
Technology, for their cooperation and coordination during the period of my
study and project work.
Special thanks are due to all the members of my family for their
role in successful completion of my study.
G.Sai Soundarya
ContentsABSTRACT.......................................................................................................1
1.Introduction:...................................................................................................2
2.Processes For Manufacture:........................................................................14
3.Process Description:.....................................................................................23
4.Material Balances:.......................................................................................25
5.Energy Balance.............................................................................................32
6.Process Equipment Design..........................................................................40
7.Instrumentation & Process Control...........................................................89
8.Materials of Construction............................................................................96
9. Plant Layout..............................................................................................100
10. Economic Analysis..................................................................................106
11.Safety And Health Hazards & pollution Control..................................109
12. References:...............................................................................................117
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ABSTRACT
The increasing demand of current world production for Maleic Anhydride
emphasizes the need to focus on the techno-economic analysis of the existing technologies.
Manufacturing of anhydride from Butane are chosen for technical analysis followed by cost
estimation and economic assessment.
The technical part involves the development of flow sheets, process design, carrying
out of calculations as well as estimation of raw materials, labor, utilities, and process
equipment by sizing and other sub-components. The economic part comprises the
estimation of working capital, fixed capital investment, total capital investment, and total
production costs. The results obtained from technical analysis and economical feasibility
studies show that the this process based technology has clear advantages in terms of raw
material consumption and economic competitiveness.
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1. Introduction:
Maleic Anhydride is a multifunctional cyclic organic chemical compound and as
the name suggests , anhydride of maleic acid. It is a major intermediate product
manufactured and consumed in large scale all over the world and has vast importance in
nearly every field of industrial chemistry.
It is an important raw material that is being extensively used in the manufacture
of pthalic type alkyd and unsaturated polyester resins, surface coatings, lubricant additives,
plasticizers and stabilizers, copolymers, food additives, preservative for oils and fats,
paper, vulcanising and modifying agents, for, rubber, synthetic polymers, permanent press
resins used in textiles and agricultural chemicals such as pesticides.
Chemical formula: C2H2(CO)2O
Structure of Maleic Anhydride:
Maleic anhydride is a 5-membered ring compound. The anhydride is a stable
compound containing two acid carbonyl groups and a double bond in α and β positions.
Nomenclature of the compound :
Maleic anhydride is a common name given to the compound based on naturally
occuring malic acid.The compound has other names based on nomenclature .the compound
is also called 2,5-Furandione , dihydro-2,5-dioxofuran,toxilic anhydride or cis-butenedioic
anhydride.
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History Of Maleic Anhydride:
Maleic Anhydride was initially amalgamated in 1830s but was not industrially
manufactured till 1933.The National Aniline And Chemical Co..,Inc ., in 1933
manufactured maleic anhydride industrially for commercial purposes, by oxidising benzene
using a vanadium oxide catalyst.
Properties Of Maleic Anhydride:
Physical Properties:
Property Maleic Anhydride
Formula C4H2O3
Molecular Weight 98.06
Physical State Solid
Colour White to colourless
Odour Chocking,irritating
Boiling point οC 202
Melting Point οC 52.85
Specific Gravity @60οC 1.31
Specific Gravity ,solid 1.43
Specific Gravity,Vapour/Air 13.38
Flash Point,οC 110
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Autoignition TemperatureοC 447
Heat Of Combustion,Kcal/mole 333.9
HeatOfFormation,solid,Kcal/mole 112.2
Heat Of Fusion,Kcal/mole 3.26
Heat Of Hydration,Kcal/mole 8.33
Heat Of Vapourisation,Kcal/mole 13.1
Dipole Moment 10-30C.m 13.2
Appearance Free flowing white solid and exists in the form of, needles,
crystals, flakes or pellets
Crystalline Form Orthorhombic
Heat Of Neutralisation KJ/mole4 126.9
Heat Capacity,KJ/(K Mol)4
Solid
Liquid
0.1199
0.164
Solubiity Data Of Maleic Anhydride:
Maleic Anhydride is soluble in organic solvents such as acetone,bezene,toulene,kerosene ,etc..,
Solvent at 25οC Maleic Anhydride
Acetone 227
Benzene 50
Toulene 23.4
o-Xylene 19.4
Kerosene .25
Chloroform 52.5
Carbon Tetrachloride 0.6
Ethyl Acetate 112
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Maleic Anhydride is a nearly planar molecule with the ring oxygen atom lying 0.003nm
out of molecular plane accorind to the data from single crystal X-Ray diffraction data . A twofold
rotation axis bisects the doublebond and passes through the ring oxygen atom.
Chemical Properties:
The broad industrial applications for this compound is due to its reactivity of the
double bond in conjugation with the two carbonyl oxygens.
Alkylation:
Maleic Anhydride reacts with alkenes activated by α-β unsaturation or an
adjacentaromatic resonance to produce succinic anhydride derivatives .the reaction
conditions are 150 to 300 C and upto 2Mpa pressure.
polyAlkenyl succinic anhydrides are prepared under these conditions by the reaction of
polyalkenes in a nonaqueous dispersion of maleic anhydride ,mineral oil and surfactant.
N-Alkylpyrroles react with maleic anhydride to give electrophilic substitution.
Acid Halide Formation:
Maleic Anhydride when treated with various reagents such as
phosgene,phthaloyl chloride or bromide ,phosphorus pentachloride ,or thionyl chloride or
thioyl halide gives 5,5-dichloro-2furanone .Maleic anhydride reacts with carbon tetra
chloride or tetra bromide at 220οC over activated carbon to form Noncyclic maleyl chloride
or bromide(6).
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Amidation :
Reaction of maleic anhydride with ammonia,primary and secondary amines
produce mono and di-amides and the reaction is known as amidation.
Maleic anhydride reacts with ammonia to form maleamic acid.
It reacts with primary amines to form amic acids that can be dehydrated to
imides ,polyimides,or isoimides depending on the reaction conditions.Amines and pyridines
decompose maleic anhydride often in a violent reaction and carbon-di-oxide is usually a
biproduct.
Miscellaneous Reactions:
1.
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2.
3. Maleic anhydride dimerizes in a photochemical reaction to form cyclobutane tetracarboxylic
dianhydride (CBTA).
4.
5.
6. Diels –Alder reaction:
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7.
Uses and World Wide consumption:
Maleic anhydride has two types of chemical functionality making it uniquely
useful in chemical synthesis and applications.The derivatives of maleic anhydride has
worldwide consumers and each structure has its own commercial interest.The majority of
maleic anhydride produced is used in unsaturated polyester resin . The other fields in which
maleic anhydride is employed is in prodction of plasticisers and stabilizers , additives and
agricultural chemicals.
1. Unsaturated polyester resins are the most commonly used thermoset resins in the
world. More than 2 million tonnes of unsaturated polyester resins are utilised
globally for the manufacture of a wide assortment of products, including sanitary-
ware, pipes, tanks, gratings and high performance components for the marine and
automotive industry. They are formulated from aromatic dibasic acid such as
phthalic anhydride, an unsaturated dibasic acid such as maleic anhydride and glycol
such as propylene glycol. The polyester chains are then cross linked through the
double bond with vinyl cross linking agents such as styrene . Reinforcement in the
form of glass fibers or other reinforcement fibers maybe added to provide the
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strength requirement of the end product .The exact unsaturated polyester formulation
,its cross linking agent and reinforcement fiber are selected to optimize the
performance of the end product.
Their versatility in use allows unsaturated polyester resins to be used in a
myriad of composite applications. Composite parts can be made at temperatures as
low as 15°C to as high as 150°C depending on the processing requirement of the
application .Unsaturated polyester resins also have excellent service temperatures.
They have good freeze-thaw resistance and can be designed for use in many low to
moderate temperature applications ranging from refrigerated enclosures to hot water
geysers.
When it comes to weight for cost comparisons, unsaturated polyester
resins are much favoured over their metallic counterparts. With the current fuel and
processing costs, the increasing prices of steel and aluminium are pushing more
fabricators to use unsaturated polyester resin composites instead. Another major
advantage is the increased productivity potential. While metals involve the use of
specific smelters, expensive tooling and processing requirements, unsaturated
polyester resins are far cheaper and afford the use of low cost tooling. An
unsaturated polyester resin can be moulded at ambient temperature whereas metals
need to be heated to well over 2000°C before they are melted and poured into mould
cavities. Although the perception is that metals are generally structurally superior,
there has been much advancement in the development of technologies for producing
higher strength composites made from unsaturated polyesters resins.
Collectively there is an ever increasing potential for unsaturated polyester
resins. Their low cost, ease of use and weight advantages make them prime
candidates for a wide variety of structural and decorative applications.
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2. Fumaric acid , succinic acid and malic acid are produced from maleic anhydride.
The primary use of fumaric acid is in manufacture of paper sizing products and is
also used as food acidulant. Malic acid is particularly desirable acidulant in certain
beverage selections , specifically those sweetened with artificial sweetener
aspartame. lube oil additives represent another important market segment for maleic
anhydride derivatives ,the molecular structure of importance being adducts of
polyalkenyl succinic anhydrides.
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3. Maleic anhydride is used in a multitude of applications in which a vinyl copolymer
is produced by the copolymerisation of maleic anhydride with other molecules
having a vinyl functionality.Typical copolymers are styrene maleic ,di-isobutylene
maleic ,acrylic acid maleic,butadiene maleic and C18 alpha olefin-maleic
(emulsification agent and paper coating).
4. Agricultural chemicals such as maleic hydrazide ,endothal, captan, have a wide
range of consumers.they are used for plant growth regulation,fungicides,isecticides,
and herbicides.
5. There are many bio degradable polymers produced from maleic anhydride such as
poly aspartic acid , which is employed in water treatment,detergent builders
etc..,.sulfosuccinic acid esters serve as surface active agents .Alkyd resins are used
as surface coatings.Chlorendricanhydride is used as a flame resistant
compoent.Tetraydropthalic acid and hexahydropthalic anhydride have resin
applications.poly malic anhydride is used as a scale preventer and corrosion inhibitor
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.Maleic anhydride forms polymer with mono-O-methyl –oligoethylene glycol vinyl
ethers ,that are esterified for biomedical and farmaceutical uses.
6.Kvamer process technology licenses a process for production of 1,4-butanediol from
maleic anhydride .This technology can be used to produce a product mix of three
molecules as needed by the producer.
World Maleic Anhydride Capacity By Region
Data in: kilotonnes per annum
Region 2002 2012
North America 235 311
South & Central America 44 41
Western Europe 168 456
Central & Eastern Europe 64 58
Asia 315 483
Africa 10 10
Total 836 1359
Source: Kirk & Othme
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The market for the maleic anhydride was around 3841.1 kilo tons per
annum in 2011 . A steady growth in both the revenue and demand for the maleic
anhydride has been observed in the following years . The graph below predicts the
growth in demand and profit of maleic anhydride in world market based on the
consensus observed and analysed.
Major Producers of Maleic Anhydride in the world (Source: Kirk & Othmer)
Company Location
Bartek Ingredients Inc. Canada
Sasol-Huntsman Germany
DSM NV The Netherlands
Flint Hills Resources LP USA
Huntsman Corporation USA
Huntsman Performance Products USA
Lanxess Corporation USA
Lonza Group AG Switzerland
Marathon Petroleum Company LLC USA
Mitsubishi Chemical Corporation Japan
Mitsui Chemicals, Inc Japan
Mitsui Chemicals Polyurethanes, Inc. Japan
Nippon Shokubai Co., Ltd Japan
NOF Corporation Japan
Polynt SpA Italy
Suzhou Synthetic Chemical Co, Ltd. China
Thirumalai Chemicals Ltd. India
TCL Industries Malaysia Sdn. Bhd. Malaysia
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2.Processes For Manufacture:
Maleic Anhydride is manufactured initially in 1930 by vapour phase
oxidation of benzene and the use of benzene as the feed for manufacture of benzene
continued till early 1980s. several processes have been employed in converting the benzene
to maleic anhydride .
Later after extensive researc into the properties of anhydride and its derivaties
various processes have been designed to obtain the anhydride of high purity at low cost.
Although, not much of economic importance these days, oxidation of butene/isobutylene, to
MA, was looked at, with interest, in 70's. A fewplants were also in operation.
Various manufacturing processes involved in the manufacture of Maleic Anhydride are
1.Manufacture of anhydride from benzene
2.Manufacturing of anhydride from Butane
3. By dehydration of Maleic Acid(very rarely employed in direct manufacture)
4.As a byprodct in the manufacture of Pthalic Anhydride.
In the manufacture of maleic anhydride from hydrocarbons like benzene and butane
various technologies such as catalyst technology, fixed bed process and fluidized bed
process technology are employed based on the requirement of the quality of product and the
economics .
1.Manufacture of maleic Anhydride using Benzene:
The primary reaction is one in which benzene is partially oxidized
to form maleic anhydride (Equation 1). There are three undesired side reactions, the
subsequent combustion of maleic anhydride (Equation 2), the complete combustion of
benzene (Equation 3), and the formation of the by-product, quinone (Equation 4).
C6H6(g)+4.5O2(g) C4H2O3(g)+2CO2+2H20 (1)
C6H6(g)+7.5O2(g) 6C02(g)+3H20(g) (2)
C4H203(g)+3O2(g) 4C02(g)+H20(g) (3)
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C6H6(G)+1.5O2(g) 6H402(g)+H20(g) (4)
(a)Catalyst Based Technology:
The catalyst for the conversion of benzene to maleic anhydride consists of
supported vanadium pentoxide .the support is sually an inert oxide such as
kieselguhr, alumina,or silica and is of low surface area as high surface area adversly
effects the conversion o benzene.The Vanadium Oxide on the surface of the support
is often modified with molybdenum oxide such the catalyst has 70% vanadium
oxide.The molybdenumOxide is said to form either a solid solution or compound
oxide with the vanadium oxide and thus increase the activity of the catalyst.
(b)Fixed Bed Process Technology:
The reactions in the fixed bed reactor are as mentioned above .The benzene
concenntrations used are about 1.5mol% or just below the lower flammable limit of
benzene in air.The reactor operates at conversions greater than 95% and molar yields
greater than 70%.The benzene oxidation reaction runs a little cooler than having
typical reactor temperatures of 350 to 400οC range.The reactor gas is cooled by one
or more heat exchanger and sent to the collection and refining section of the
plant.unreacted benzene and by-products are incinerated.
2.Manufacture Of Anhydride Using Benzene:
The manufature of maleic anhydride by butane as feed stock is similar to
benzene process except the processing conditions and catalyst.Butane is oxidised
using the oxygen in the air .The following reactions occur in the reactor during the
production of maleic anhydride. The oxidation of butane is an exothermic reaction &
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from the reactions mentioned , carbon –di-oxide and cabon-mono-oxide are the
major byproducts obtained during the conversion.
C4H10(g)+3.5O2(g) C4H2O3(g)+4H20 (1)
C4H10(g)+5.5O2(g) 2C02(g)+5H20(g)+2CO (2)
C4H10(g)+3.5O2(g) C02(g)+3H20(g)+C3H4O2 (3)
C4H10(G)+6O2(g) CH202(g)+4H20(g)+3CO2 (4)
(a)Catalyst Based Technology:
The catalyst used in the manufacture of maleic anhydride is vanadium
phosphorus oxide.During the conversion of butane to maleic anhydride there is a
complexity in the reaction.The eight hydrogen atoms must be extracted from butane
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and three oxygen atoms has to be inserted and a ring closure has to occur.The 14
elctrn oxidations occurs extensively on the surface of catalyst. Hence ,eventhough
many catalyst based manufacturing processes are employed the catalyst used is
VPO in all processes.
(b)Fixed Bed Process Technology:
Air is compressed to modest pressures, typically 100 to 200 kPa with either a
centrifugal or axial compressor, and mixed with superheated vaporized butane. Static mixers
are normally employed to ensure good mixing. Butane concentrations are often limited to
less than 1.7 mol % to stay below the lower flammable limit of butane . Operation of the
reactor at butane concentrations below the flammable limit does not eliminate the
requirement for combustion venting, and consequently most processes use rupture disks on
both the inlet and exit reactor heads. The highly exothermic nature of the butane-to-maleic
anhydride reaction and the principal by-product reactions require substantial heat removal
from the reactor. Thus the reaction is carried out in what is effectively a large multitubular
heat exchanger which circulates a mixture of 53% potassium nitrate, KNO3; 40% sodium
nitrite , NaNO2; and 7% sodium nitrate , NaNO3.
Reactor temperatures are in the range of 390 to 430οC. Despite the rapid
circulation of salt on the shell side of the reactor, catalyst temperatures can be 40 to 60οC
higher than the salt temperature. The butane to maleic anhydride reaction typically reaches
its maximum efficiency (maximum yield) at about 85% butane conversion. Reported molar
yields are typically 50 to 60%. Efficient utilization of waste heat from a maleic anhydride
plant is critical to the economic viability of the plant. Often site selection is dictated by the
presence of an economic use for by-product steam. The steam can also be used to drive an
air compressor, generate electricity, or both. Alternatively, an energy consuming process,
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such as a butanediol plant, can be closely coupled with the maleic anhydride plant. Several
such plants have been announced . Design and integration of the heat recovery systems for a
maleic anhydride plant are very site specific. Heat is removed from the reaction gas through
primary and sometimes secondary heat exchangers. In addition to the heat recovered from
the reactor and process gasheat exchangers, additional heat can be recovered from the
destruction of unreacted butane, the carbon monoxide by-product, and other by-products
which cannot be vented directly to the atmosphere. This destruction is done typically in a
specially designed thermal oxidizer or a modified boiler. Reactor operation at 80 to 85%
butane conversion to produce maximum yields provides an opportunity for recycle
processes to recover the unreacted butane in the stream that is sent to the oxidation reactor.
Patents have been issued on recycle processes both with and without added oxygen.
Pantochim has announced the commercialization of a partial recycle process . Mitsubishi
Chemical Corporation has announced plans to add butane recovery from the offgas of their
fluid bed process through the use of BOC Gases’ proprietary selective hydrocarbon
separation system (PETROX) . This technology is particularly well suited to use in fluid bed
processes where the hydrocarbon to air ratio is relatively high and in world areas where
butane has a high value relative to its energy content. Operation of the butane to maleic
anhydride process in a total recycle configuration can produce molar yields that approach
the reaction selectivity which is typically 65 to 75%, significantly higher than the 50 to 60%
molar yields from a single pass, high conversion process. The Du Pont transport bed process
achieves its high reported yields at least partially through implementation of recycle
technology. Recovery of the fuel value of the
butane in the offgas from a single pass configuration plant reduces the economic
attractiveness of recycle operation.
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(C) Fluidized-Bed Process Technology:
Fluidized-bed processes offer the advantage of excellent control of hot spots by rapid
catalyst mixing, simplification of safety issues when operating above the flammable limit,
and a simplified reactor heat-transfer system. Some disadvantages include the effect of back
mixing on the kinetics in the reactor, product destruction and by-product reactions in the
space above the fluidized bed, and vulnerability to large-scale catalyst releases from
explosion venting. Compressed air and butane are typically introduced separately into the
bottom of the fluidized-bed reactor. Heat from the exothermic reaction is removed from the
fluidized bed through steam coils in direct contact with the bed of fluidized solids.
Fluidized-bed reactors exploit the extremely high heat-transfer coefficient between the bed
of fluidized solids and the steam coils. This high heat-transfer coefficient allows a relatively
small heattransfer area in the fluid-bed process for the removal of the heat of reaction
compared to the fixed-bed process. Gas flow patterns in a commercial scale fluid-bed
reactor are generally backmixed, which can lead
to maleic anhydride destruction.
Fluidized-bed reactors require a significant amount of space above the catalyst
level to allow the solids to separate from the gases. This exposure of the product to high
temperatures at relatively long residence times can lead to side reactions and product
destruction. Fluidized-bed processes are operated at high butane concentrations but at longer
gas residence times than fixed-bed processes. The product stream contains gases and
solids. The solids are removed by using either cyclones, filters, or both in combination.
Cyclones are devices used to separate solids from fluids using vortex flow. The product gas
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stream must be cooled before being sent to the collection and refining system. The ALMA
process uses cyclones as a primary separation technique with filters employed as a final
separation step after the off-gas has been cooled and before it is sent to the collection and
refining system . As in the fixed bed process, the reactor off-gas must be incinerated to
destroy unreacted butane and by-products before being vented to the atmosphere. Fluidized-
bed reaction systems are not normally shut down for changing catalyst. Fresh catalyst is
periodically added to manage catalyst activity and particle size distribution. The ALMA
process includes facilities for adding back both catalyst fines and fresh catalyst to the
reactor.
3.By Dehydration of Maleic Acid:
Maleic anhydride can also be obtained by dehydration of maleic acid that is a
byproduct of petroleum industry. This is a rarely used industrial process but is a process
mostly employed at lab scale.The high process conditions and the reactivity of acid to form
acid derivatives and also the economics involved in the dehydration process are the main
reasons for not employing this process industrially on a large scale. The dehydration occurs
in the presence of phosphorus pentoxide to form the anhydride and water.
4. Byproduct Of Pthalic Anhydride Production:
Maleic anhydride is, also, formed as a by-product, from phthalic anhydride
process. From the, present, six phthalic anhydride plants,with an installed capacity of 55,000
TPA, about 2,000 TPA of MA is recoverable.
C6H4(CH3)2 + 3 O2 → C6H4(CO)2O + 3 H2O
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The reaction proceeds with about 70% selectivity. About 10% of maleic anhydride is also
produced
C6H4(CH3)2 + 7.5 O2 → C4H2O3 +4 H2O + 4 CO2
(II) Recovery and Purification:
All processes for the recovery and refining of maleic anhydride must deal with
the efficient separation of maleic anhydride from the large amount of water produced in the
reaction process. Recovery systems can be separated into two general categories: aqueous-
and nonaqueous-based absorption systems. Solvent-based systems have a higher recovery of
maleic anhydride and are more energy efficient than water-based systems.
The Huntsman solvent-based collection and refining system will be used as a
generic model for solventbased recovery systems .The reactor exit gas is cooled in two heat
exchangers for energy recovery. The cooled gas product stream is passed to a solvent
absorber where a proprietary solvent is used to absorb, almost completely, the maleic
anhydride contained in the product stream. The solvent stream, coming from the bottom of
the absorber with a high concentration of maleic anhydride, known as rich oil, is sent to a
stripper where the rich oil is heated and maleic anhydride is vacuum stripped from the
solvent. The vacuum-stripped maleic anhydride is typically greater than 99.8% purity, and is
sent to the purification section of the plant where it is batch distilled to produce extremely
pure maleic anhydride. A small slip stream of the solvent which has had the maleic
anhydride removed by stripping is sent to the solvent purification section of the plant where
impurities are removed. The Scientific Design water-based collection and refining system is
in broad use throughout the world in butane-based and benzene-based plants . The reactor
off-gas is cooled from reaction temperatures in a gas cooler with generation of steam. The
off-gas is then sent to a tempered water-fed aftercooler where it is cooled below the dew
point of maleic anhydride. The liquid droplets of maleic anhydride are separated from the
off-gas by a separator. The condensed crude is pumped to a crude tank for storage. The
maleic anhydride remaining in the gas stream after partial condensation is removed in a
water scrubber by conversion to maleic acid which accumulates in the acid storage section
at the bottom of the scrubber. The acid solution is converted to crude maleic anhydride in a
dual purpose dehydrator/refiner. Xylene is used as an azeotropic agent for the conversion of
maleic acid to maleic anhydride. Water from the dehydration step is recycled to the
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scrubber. When the conversion of the acid solution to crude maleic anhydride is complete,
condensed crude maleic anhydride is added to the still pot and a batch distillation refining
step is conducted. The UCB collection and refining technology also depends on
partial condensation of maleic anhydride and scrubbing with water to recover the maleic
anhydride present in the reaction off-gas. The UCB process departs significantly from
the Scientific Design process when the maleic acid is dehydrated to maleic anhydride. In the
UCB process the water in the maleic acid solution is evaporated to concentrate the acid
solution. The concentrated acid solution and condensed crude maleic anhydride is converted
to maleic anhydride by a thermal process in a specially designed reactor. The resulting crude
maleic anhydride is then purified by distillation.
(iii)Merits Of Butane Over Benzene for The Manufacture of Anhydride:
Benzene, although easily oxidized to maleic anhydride with high selectivity,
is an inherently inefficient feedstock since two excess carbon atoms are present in the raw
material. The price of benzene and its hazardous properties are other factors that
overshadow the yield obtained in the process and hence butane based production has been
replacing the benzene based technologies .
In 1983, Monsanto started up the world's first butane-to-maleic anhydride
plant, incorporating an energy efficient solvent-based product collection and refining
system. This plant was the world's largest maleic anhydride production facility in 1983 at
59,000t/yr capacity, and through rapid advances in catalyst technology has been
debottlenecked to a current capacity of 105,000t/yr (1999). Advances in catalyst technology,
increased regulatory pressures, and continuing cost advantages of butane over benzene have
led to a rapid conversion of benzene- to butane-based plants. By the mid-1980s in the
United States 100% of maleic anhydride production used butane as the feedstock.
Coincident with the rapid development of the butane-based fixed-bed process, several
companies have developed fluidized-bed processes. Two companies, Badger and Denka,
collaborated on the development of an early fluid-bed reaction system which was developed
through the pilot-plant stage but was never commercialized. Three fluid-bed, butane-based
technologies were commercialized during the latter half of the 1980s by Mitsubishi Kasei,
Sohio (British Petroleum), and Alusuisse. A second fluidized-bed technology for the
oxidation of butane to maleic anhydride, known as transport bed, has been developed by Du
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Pont. A world-scale plant in Spain for the production of THF by the hydrogenation of
maleic acid using this technology began production in 1996 . Europe has largely converted
from benzene-based to butane-based maleic anhydride technology with the construction of
several new butane based facilities by CONDEA-Huntsman, Pantochim and Lonza.
3.Process Description:
Pure butane, Stream 2, and compressed air, Stream 3, are mixed and fed to
R-101, an adiabatic reactor, where butane reacts with oxygen to form maleic anhydride.
The reaction is exothermic, therefore, one could consider either a fluidized bed reactor or a
packed bed reactor with heat removal to stay close to isothermal. The reactor effluent is
cooled and sent to T-101, a packed bed absorber, where it is contacted with water, Stream 7,
to remove the light gases and all of the maleic anhydride reacts to form maleic acid. The
vapor effluent, which consists of non- condensables , Stream 8, must be sent to an after-
burner to remove any carbon monoxide prior to venting to the atmosphere. This is not
shown here. The liquid effluent, Stream 9, is then cooled and flashed at 101 kPa and 120°C
in V-101. The vapor effluent from V-101, Stream 11, is sent to waste treatment. Stream 12,
the liquideffluent, is sent to R-102 where maleic acid is broken down to maleic anhydride
and water. The reactor effluent is then sent to distillation column, T-102, where maleic
anhydride and water are separated. The distillate, Stream 14, is sent to waste treatment.
Stream 15, the bottoms, consists of 99-wt.% maleic anhydride.
The conversion of butane is assumed to be 82.2%. The selectivity for each reaction is as
follows [2]:
(1) maleic anhydride 70.0%
(2) carbon dioxide 1.0%
(3) acrylic acid 1.0%
P a g e | 24
(4) formic acid 1.0%
Data that may provide reaction kinetics can be found in US patent 4,317,778.
FLOW SHEET FOR THE MANUFACTURING PLANT
Equipment Summary:
C-101 Air Compressor
E-101 Heat Exchanger
E-102 Heat Exchanger
E-103 Condenser
E-104 Reboiler
P-101A/B Reflux Pump
R-101 Packed Bed Reactor
R-102 Maleic Acid Reactor
P a g e | 25
T-101 Absorption Tower
T-102 Distillation Column
V-101 Flash Vessel
V-102 Reflux Vessel
4.Material Balances:
4.1- Reactor
Air entering at 25 0C and assume the Humidity is 65% from the Psychometer chart
H= 0.018kg water/kg dry air
=0.03 kgmol water/kgmol dry air.
Basis:
120 ton of maleic anhydride per day.
According to US Patent # 4317778 air is provided in this reaction is
Bu : O2
1 : 8.65 (in mol fraction )
From Encyclopedia
Butane unreacted = 17% of entering
Butane converted to maliec anhydride = 53% of entering
Butane converted to Acrilic acid = 1.1% of entering
Butane converted to formic acid = 1.07% of entering
Butane entering = 116 ton/day
= 1829 Kgmol/day
O2 required = 1829*8.65
= 15820.85 kgmol/day
= 553.6 ton/day
N2 required = 15820.85*0.79/0.21
P a g e | 26
= 59516.7 kgmol/day
= 1822.26 ton/day
Hence ,total dry air = 75337.55 kgmol/day
H2O with air = 75337.55*0.03
= 2260.1kgmol/day
= 44.48 ton/day
So butane coming out = 0.17*1829
= 310.83kgmol/day
= 19.72 ton/day
Butane converted to
maliec anhydride = 0.53*1829
= 969.37 kgmol/day
= 103.88 ton/day
Acrilic acid = 0 .011*1829
= 20.119kgmol/day
= 1.584ton/day
formic acid = 0.0107*1829
= 19.57kgmol/day
= 0.9844ton/day
Total butane in-butane consumed = butane coming out of reactor
1829-(969.37+20.119+19.57+x) = 310.93
x=amount of butane consume in cox = 509.01kgmol/day
From the reactions given by stochiometry
P a g e | 27
O2 Balance:
O2 consumed in reaction (1) = 3.5*969.37
= 3392.79
kgmol/day
O2 consumed in reaction (2) = 5.5*509.01
= 2799.56 kgmol/day
O2 consumed in reaction (3) = 3.5*20.119
= 70.42 kgmol/day
O2 consumed in reaction (4) = 6*19.57
= 117.42
kgmol/day
Total O2 consumed = 6380.19 kgmol/day
O2 leaving un reacted = O2 entering -O2 consumed
= 15820-6380.19
= 9439.81 kg mol/day
= 330.342 ton/day
CO2Balance
CO2 produced in reaction in (2) = 2*509.01
= 1018.02
kgmol/day
CO2 produced in reaction in (3) = 1*20.119
= 20.119
kgmol/day
CO2 produced in reaction in (2) = 3*19.57
= 58.71 kgmol/day
Total CO2 produced = 1096.85kg mol/day
= 52.77 ton/day
CO Balance
P a g e | 28
CO produced in reaction in (2) = 2*509.01
= 1018.02 kgmol/day
Total CO produced = 1018.02kgmol/day
= 31.17 ton/day
H2O Balance:
H2O produced in reaction (1) = 4*969.37
= 3777.48 kgmol/day
H2O produced in reaction (2) = 5*509.01
= 2545.05 kgmol/day
H2O produced in reaction (3) = 3*20.119
= 60.357 kgmol/day
H2O produced in reaction (4) = 4*19.57
= 18.57 kgmol/day
Total water produced = 6567.17 kgmol/day
Water with air = 2260.1 kgmol/day
Total H2O outlet = 8821.29 kgmol/day
= 173.63 ton/day
4.2 Material Balance around absorber:
The solubility of Butane in water is 0.0098 kgmol butane/kgmol water at 60 oc and the
solubility of CO, CO2, N2and O2 is negligible.
Water required for absorption = 310.93/0.0098
=31727.55 kgmol/day
= 625 ton/day
P a g e | 29
4.3 Balance around flash vessel:
Stream entering in flash vessel is given below
H2O=778.788 t/d
C3H4O2=1.548 t/d
CH2O=0.9844 t/d
C4H4O4= 103.88 t/d
C4H10=19.33t/d
Total moles entering =40880.53 kgmol/day
Zj=mol fraction in feed
Xj=mol fraction in liquid in outlet
Yj=mol fraction in vapour in outlet
V/F= vapour to feed ratio
Pj=vapour pressure of component supposed
P=Total pressure
By hit and trail method
At 120 oC and
V/F=0.95
Components
Zj Pj
KPa
PPj
1 1 PP FV
Z X i j j
j j X PP Yi
C4H10 0.0076 2068.5 20.41 0.000391 0.00797
CH2O 0.00047 179.27 1.769 0.000272 0.00048
C3H4O2 0.0005 51.7125 0.51 0.000935 0.000477
C4H4O3 0.024 0.06895 0.00068 0.4738 0.000322
H2O 0.967 193.06 1.91 0.5198 0.9905
P a g e | 30
Total 1.000 0.996 0.999
components Liquid stream
kgmol
L*Xj
vapour stream
kgmol
V*Yj
C4H10 0.799 303.91
CH2O 0.55 19.02
C3H4O2 1.83 18.291
C4H4O4 969 0.37
H2O 1072.34 38494.42
4.4 Balance around maleic acid reactor:
By the ref
At 135 oc maliec acid rapidly decomposes into maliec acid and water according to the
reaction
C4H4O4 C4H2O3+H2O
So, H2O produced =969 kgmol /day
Total H2O =969+1072.34=2041.34 kgmol /day=40.18ton/day
Maliec acid produced =969 kgmol/day=103.841ton/day
Maliec acid reactor:
H2O=21.11 t/d C3H4O2=0.144 t/d CH2O=0.0276 t/d C4H4O4= 122.91 t/d C4H10=0.051t/d
H2O=40.18 t/d C3H4O2=0.144 t/d CH2O=0.0276 t/d C4H2O3= 103.8411 t/d C4H10=0.051t/d
4.5 Balance around distillation column :
P a g e | 31
As Butane, Formic acid and Acrylic acid are so small that they can be neglected.
It is assumed that 98% of water is in distillate and 99% maleic acid in bottom.
Feed stream:
H2O= 2041.35 kgmol/day
C4H2O3=969 kgmol/day
C4H10=0.85kgmol/day
CH2O=0.546 kgmo/day
C3H4O2=1.829kgmol/day
Overall balance :
F=D+W --------------1
D+W=3010.35
Maliec acid balance :
0.02*D+0.98*W=966.32---------2
By solving equation 1&2
D= 2063.93 kgmol/day
W=946.42 kgmol/day
Residue:
Maliec acid = 0.98*946.42=927.48kgmol/day=100ton/day
H2O=0.02*946.42=18.93 kgmol/day
Acrylic acid=0.9148 kgmol/day
Formic acid=0.011 kgmol/day
Distillate:
Maliec acid = 41.32 kgmol/day
H2O= 2025.43kgmol/day
P a g e | 32
Acrylic acid= 0.9145kgmol/day
Formic acid=05377 kgmol/day
Butane=0.8047 kgmol/day
5.Energy Balance
5.1 Energy Balance around Air Compressor:
Inlet flow rate =77597.65 Kmol/day= 0.898 kmol/s
Inlet volumetric flowrate:
Where
n=0.898kmol/s
R=0.0821 m3atm/kmol K
P= 1 atm
T=298 K
On substitution,
V=21.97 m3/s
From fig 3.6 of Coulson & Richardson- vol 6, for this flow rate centrifugal compressor
would be used with efficiency EP=75%.
V = nRT/P
P a g e | 33
Outlet temperature for Air:
where
T1=25 oC =298K
P1=101.325Kpa
P2=300 Kpa
m=(γ-1/γEP )
For Air, γ=1.4
On substitution,
m= 0.38
T2=177.6οC=450.6K
Work required per Kmol:
Where
n=(1/1-m)=1.61
Z1=1 (at 25 oC and 1 atm from Perry Handbook)
R=8.314 kJ/KmolK
On substituting
W=3326.56KJ/Kmol
Power requirement:
On substituting
P=3.983MWatt
5.2 Energy Balance around Butane Compressor:
Inlet flow rate =1829 Kmol/day= 0.021 kmol/s
T2= T1*(P2/P1)m
W=Z1T1R1(n/n-1)[(P2/P1)(n/n-1) -1]
P= (W ×0.898Kmol/s)/EP
P a g e | 34
Inlet volumetric flowrate:
Where
n=0.021kmol/s
R=0.0821 m3atm/kmol K
P= 1 atm
T=298 K
On substitution,
V=0.51m3/s
From fig 3.6 of Coulson & Richardson- vol 6, for this flow rate centrifugal compressor
would be used with efficiency EP=67%.
Outlet temperature for Air:
where
T1=25 oC =298K
P1=101.325Kpa
P2=300 Kpa
m=(γ-1/γEP )
For Butane, γ=1.135
On substitution,
m= 0.177
T2=88.32οC=361.32K
Work required per Kmol:
Where
n=(1/1-m)=1.216
Z1=0.98(from fig 3.8 Coulson & Richardson vol 6)
R=8.314 kJ/KmolK
V = nRT/P
T2= T1*(P2/P1)m
W=Z1T1R1(n/n-1)[(P2/P1)(n/n-1) -1]
P a g e | 35
Here,
Tc=425.1 K,
Pc=37.96 bar
We know,
Tr=Tc/T1=0.701,
Pr=P1/Pc=0.0263
On substituting
W=2906.72KJ/Kmol
Power requirement:
On substituting
P=0.091MWatt
5.3 Energy Balance around Mixing Tee:
For a mixer,
Where
ni = no. of moles of ith component
Cpi = heat capacity of ith component
T1 = reference temperature
P= (W ×.021Kmol/s)/EP
Q=∑niʃCPidT (from T1 to T2)
T=?
Butane
T2=88.32 οC
Air
T2=177.14 οC
P a g e | 36
T2= final temperature
For Air,
T1=25οC
T2 = 177.14oC
For Butane,
T1 = 25o C
T2 = 88.32oC
Qin = QA +QB
On Substituting,
Qin= 3.6* 108 kJ/day
We know,
Qin = Q out
On substituting,
T4= 155oC
Q H f P H f R
W=Q/CP∆T
5.4 Around reactor:-
Inlet feed temperature = T1 =155 oC
Out let product temperature T2= 410 oC
Inlet cooling water temperature=t1= 25 oC
Outlet cooling water temperature=t2= 70 oC
Sensible energy
Is given by eq.
where
ni = no. of moles of ith component
Q1=∑niʃCPidT (from T1 to Tref)
P a g e | 37
Cpi = heat capacity of ith component
T1 = reference temperature=25 oC
where
ni = no. of moles of ith component
Cpi = heat capacity of ith component
T1 = reference temperature=25 oC
Q = Q2 -Q1
On Substituting,
Q= 6.5* 108 kJ/day
Heat of reaction
is given by following equation
Q H f P H f R
=-3.19*109 +7.75 * 10 8
= -2.4*109 kJ/day
Q evolved = Q + Q2
= -1.76*109 kj/day
Where ‘–ve’ sign shows that heat is evolved
Amount of water required:-
W=Q2/CP∆T
where
Cp = 4.184 KJ/kg oC
W= 9.3* 106 KJ / day
5.5 Around heat exchanger (E-101)
Inlet temperature =T1=410oC
Q2=∑niʃCPidT (from T1 to Tref)
P a g e | 38
Out let temperature =T2=90 oC
Q=8.2*108KJ/day
5.6 Around absorber
Feed inlet temperature=T2 =90oC
Water inlet temperature=25 oC
Outlet temperature =T=?
where
T1= ref temperature =25oC
Qin =1.59*108 kJ/day
We know,
QIN=QOUT
On substituting
T=90oC
5.7 Around heat exchanger (E-102)
Inlet temperature =T1=90oC
Out let temperature =T2=120 oC
Q=4.9*107KJ/day=574 kJ/s
5.8 Around heat exchanger (E-103)
Inlet temperature =T1=120oC
Out let temperature =T3=160 oC
Reaction temperature T2=135 oC
Q=∑niʃCPidT (T1 to T2)+∆HR+∑niʃCP dt (T2 to T3)
Q=∑niʃCPidT (from T1 to T2)
QIN=∑niʃCPidT (from T1 to T2)
Q=∑niʃCPidT (from T1 to T2)
P a g e | 39
=1.2*106+3.4*107+2.86*106
=1.7*108KJ/day
Q=2019.35KJ/s
5.9Around distillation column
Condenser
Energy balance equation of condenser is
H1Vn=[Lnhd+Dhd]+Qc
H1=∑Hliyni at Ti
= 0.979*2886.91+0.0199*1878.34
=2864 KJ/Kmol
hd=∑hdixdi
=0.979*2564.78+0.0199*1568.64
= 2542.14 KJ/Kmol
Qc=71392 KJ/hr =19.83 kJ/s
latent heat of water =λ1= 40683KJ/Kmol
m λ1=0.979*221.5*40683
=8822047.5 KJ/hr
=2450.6Kwatt
latent heat of malice anhydride = λ2= 54800KJ/Kmol
m λ2=0.0199*221.5*57800
=241550.2 KJ/hr
=67Kwatt
Qact=Qc+m λ1+m λ2
=2537.43KWatt
Around reboiler
Temperature =185 oC (isothermal)
Vapour required =m=96Kmol/hr
Q=m λ=1452.23KJ/s
P a g e | 40
Since the feed enters and leaves isothermally at 185 oC
So sensible heat is zero
5.10 Condenser after Flash Vessel
Qi=∑niʃCPidT+ m λ
where
T1= inlet temperature =120oC
T2=outlet temperature = 100oC
λ = latent heat of vapourization
Qt = 1.69*109 KJ/day
6.Process Equipment Design6.1 Fixed Bed Catalytic Reactors
Introduction:
Fixed-bed catalytic reactors have been aptly characterized as the workhorses of me
process industries. For economical production of large amounts of product, they are usually
the first choice, particularly for gas-phase reactions. Many catalyzed gaseous reactions are
amenable to long catalyst life (1-10 years); and as the time between catalyst change outs
increases, annualized replacement costs decline dramatically, largely due to savings in
shutdown costs. It is not surprising, therefore, that fixed-bed reactors now dominate the
scene in large-scale chemical-product manufacture.
Types of Fixed Bed Reactor:
Fixed-bed reactors fall into one of two major categories:
Adiabatic or
Non-adiabatic.
P a g e | 41
A number of reactor configurations have evolved to fit the unique requirements of
specific types of reactions and conditions. Some of the more common ones used for gas-
phase reactions are summarized in Table (4.1) and the accompanying illustrations. The table
can be used for initial selection of a given reaction system, particularly by comparing it with
the known systems indicated.
Fixed-Bed Reactor Configurations for Gas-Phase Reactions:
Classification Use Typical Applications
Single adiabatic bed
Moderately exothermic Mild hydrogenation
or
endothermic non-
equilibrium
limited
Radial flow Where low AP is Styrene from
essential ethylbenzene
and useful where
change
in moles is large
Adiabatic beds in series High conversion, SO2 oxidation
with intermediate equilibrium Catalytic reforming
cooling or heating limited reactions Ammonia synthesis
Hydrocracking Styrene
from ethylbenzene
Multi-tabular Highly endothermic or Many hydrogenations
non-adiabatic exothermic reactions Ethylene oxidation to
requiring ethylene oxide,
P a g e | 42
close temperature formaldehyde
control to by methanol oxidation,
ensure high selectivity phthalic anhydride
production
Direct-fired Highly endothermic, Steam reforming
non-adiabatic high temperature
reactions
1. SELECTION OF REACTOR TYPE
After analyzing different configuration of fixed bed reactors we have concluded that
for our system the most suitable reactors is multi tube fixed bed reactor. Because oxidation
of butane is highly exothermic reaction, so cooling will be required otherwise the
temperature of reactor will rise and due to rise in temperature the catalyst activity and
selectivity will be affected and in turn, the formation of by-products will increase which is
direct loss of productions.
As reaction temperature is already high 410 oC if we keep the process adiabatic temperature
of reactor will rise and the structure of the catalyst will be changed and catalyst will be
damaged. For such a situation the best reactor is multi-tube fixed bed reactor .
2. CONSTRUCTION AND OPERATION OF MULTI-TUBE FIXED BED REACTOR
Because of the necessity of removing or adding heat, it may not be possible to use
a single large-diameter tube packed with catalyst. In this event the reactor may be built up
of a number of tubes encased in a single body, as illustrated in Fig. The energy exchange
with the surroundings is obtained by circulating, or perhaps boiling, a fluid in the space
between the tubes. If the heat effect is large, each catalyst tube must be small (tubes as small
as 1.0-in. diameter have been used) in order to prevent excessive temperatures within the
reaction mixture. The problem of deciding how large the tube diameter should be, and thus
how many tubes are necessary, to achieve a given production forms an important problem in
the design of such reactors.
P a g e | 43
A disadvantage of this method of cooling is that the rate of heat transfer to the fluid
surrounding the tubes is about the same all along the tube length, but the major share of the
reaction usually takes place near the entrance. For example, in an exothermic reaction the
rate will be relatively large at the entrance to the reactor tube owing to the high
concentrations of reactants existing there. It will become even higher as the reaction mixture
moves a short distance into the tube, because the heat liberated by the high rate of reaction is
greater than that which can be transferred to the cooling fluid. Hence the temperature of the
reaction mixture will rise, causing an increase in the rate of reaction. This continues as the
mixture moves up the tube, until the disappearance of reactants has a larger effect on the
rate than the increase in temperature. Farther along the tube the rate will decrease. The
smaller amount of heat can now be removed through the wall with the result that the
temperature decreases. This situation leads to a maximum in the curve of temperature versus
reactor-tube length.
EFFECT OF VARIABLES ON MULTI-TUBE FIXED BED
REACTOR
Particle Diameter
The overall heat transfer coefficient declines with decrease in particle size in the
usual practical range. Redial gradients increase markedly with decrease in particle size.
Small size, however, may improve rate or selectivity in some case by making catalyst inner
surface more accessible.
P a g e | 44
Tube Diameter
Reducing tube diameter reduces the radial profile. Heat transfer area per unit volume
is inversely proportion al to the tube diameter and reaction temperature is affected by a
change in this area.
Outside Wall Coefficient
Improvement up to the point where this resistance becomes negligible is worthwhile.
Boiling liquids are advantageous because of the high heat transfer coefficient.
Heat of Reaction and Activation Energy
Accurate values should be used since calculated temp. is sensitive to both of these,
particularly to the value of energy of activation. This roust be determined carefully over the
range of interests, but calculated results should be obtained based on different activation
energies over the probable range of accuracy for the data so that final equipment sizing can
be done with a feel for uncertainties.
Particle Thermal Conductivity
One of the mechanisms of radial heat transfer in a bed, conduction through the solid
packing which must quite logically depend on the thermal conductivity of the bed, can be
reasoned to have some dependence on the thermal conductivity of the solid. But since it
only affects one of the several mechanisms, the proportionally cannot be direct. Differences
in effective conductivity and the wall heat transfer coefficient h between beds of packing
P a g e | 45
having high and low solid conductivity may be in the range of a factor of 2-3. The largest
difference will occur at lower Reynolds numbers. Most catalyst carriers have low
conductivities, but some such as carbides have high conductivities.
Design Procedure for Multi-Tubular Fixed Bed Reactor
To calculate weight of catalyst required
If space time is know then
By the knowledge of bulk density of catalyst and weight of catalyst calculate volume
of reactor
Decide the dimensions of tube; keeping in mind that
Calculate volume of one tube and then number of tubes required
Calculate Shell Dia
Calculate Pressure Drop
Dia of tube/dia of catalyst particle>10
Volume of reactor = weight of catalyst / bulk density of catalyst
space time = Volume of reactor/Volume of flow rate
W/FA0=∫X A3
X A 2
dX A/-rA
No. of tubes = Volume of Reactor / Volume of one tube
NT=[[(Ds-k1 )2 π4
+k2 ]-Pt(Ds-k1)(nk3-k4)]/1.223(Pt)2
∆ PL
= (1−ε
ε¿( G
D ρC )¿]
P a g e | 46
Calculate heat transfer co efficient
i. Shell Side
ii. Tube Side
iii. Calculate overall heat transfer coefficient
Calculate area required for heat transfer
Calculate area available for heat transfer
*Area available should be greater than required area
Design Calculations for Multi-Tubular Fixed Bed Reactor
Volume of Reactor
Volumetric flow rate of feed to reactor = Vo = 19.04 m3/s
Space time = τ = 0.15s Ref [US Patent #4317778]
Volume of reactor =V= τVo =2.86 m3
Type and volume of Catalyst
Vanadium Phosphorus Oxide (VPO) catalyst of 0.48 cm in the form of pellet is used
Bed void fraction =φ = 0.4
From the appendix table 1.1
h0=150 (1+0.011 t b )¿¿
hp d
k=3.50(
d pG
μ)e
−4.6d p
d
P a g e | 47
volume of catalyst = (1-φ )V= 1.72 m3
weight of catalyst
Bulk density of VPO =ρc=2836 Kg/m3 Ref [www.chemistry periodic table .htm.]
Weight of catalyst = Vcρc= 4103.92 Kg
Tube length and diameter
Take length and diameter of tube to prevent deviation from plug flow assumption.
From appendix table 1.2 Dt/Dp > 10 & L/Dp>100
Where
Dt = diameter of tube
Dp = diameter of particle
L=length of tube
Take L=250 cm ,Dt=5cm
Dt/Dp=10.48 & L/Dp=520.83( Satisfactory )
Number of Tubes
Volume of one tube = Vt = /4 Dt2 L
Dt = 0.05m L = 2.5 m
Vt = 0.006 m3
Total number of tubes = Nt=V/Vt
V = reactor volume =2.86 m3
Nt = 584
Tube layout
Tube layout is triangular.
P=1.25Do
Where P= tube pitch
Do=outside tube diameter
Do= 6 cm
P = 7.5
Number of tubes at bundle diameter
P a g e | 48
ND = number of tubes at bundle diameter
Nt= total number of tubes = 584
On Substituting, ND =28
Where P= tube pitch
ND = number of tubes at bundle diameter
Di = shell diameter
On Substituting, Di = 2.1 m
Shell Height
Length of tube = 2.5 m
Leaving 20 % spacing above and below
So height of shell = 2 (0.2 2.5) + 2.5 = 3.5 m
Pressure Drop
Tube Side
= bed void fraction = 0.4
DP = particle diameter = 4.8 mm = 0.48 cm
ρf= feed density = .00269 g/cm3
G = mass velocity = 0.274 g/cm2 Sec
μ = viscosity of feed = 0.00022 g/cm. Sec
gc = 980.67 cm2/sec
L = length = 2.5 m = 250 cm
Putting values in above eq. gives
N D=¿
Di=P [N D+1]
∆ PL
= (1−ε
ε¿( G
D ρC )¿]
P a g e | 49
ΔP = 267.5 gm/cm2
And 1033.074 g/cm2 = 1 atm
So ΔP = 0.25 atm
Shell side pressure drop
Mass flow rate = mw=107 kg/s = 235.4 lb/s
Flow area
Where
Ds=shell inside diameter= 82.656 in
Nt=total number of tubes = 584
Dot=tube outside diameter= 2.375 in
Ac= 2778.65 in2= 1.79 m2
Wetted primeter =π Nt Dot
= 4357.4 in
De= (4*flow area)/wetted primeter
Where De= Equivalent diameter= 2.55 in = 0.21 ft
G= mw/Ac
Where G= mass velocity =19.2 lb/ft2/s
Reynolds Number
De=equivalent diameter=0.21ft
μ=viscosity=0.000403 lb/ft/s
Re=10004.96
From appendix fig.1.1
Friction factor for tube side = f = 0.00025
Ac=π4
¿]
Re=GDe
μ
∆ PS=fGS
2 ln
5.22× 1010 D e φ
P a g e | 50
Where
∆Ps= pressure drop
Gs= shell side mass velocity= 43920 lb/ft2/hr
L= length of tube = 8.2ft n= number of passes=1
De=Equivalent diameter=0.21ft
S= specific gravity=1
Ps=0.00036 psi (Negligible )
Calculations of Heat Transfer Co-efficient:
Shell side
tb = average water temperature; oF
= 117.5 oF
De=Equivalent Diameter, in
De = 2.55 in
Now to calculate V’ = velocity of water in fps
Mass velocity = G = 19.92 lb/ft2/s
Water density =ρW =62.3lb/ft3
Water Velocity=V’=0.031fps
On Substituting,
hο=184.09 Btu/ hr. ft2 oF
Wall
ΦS=¿
h0=150 (1+0.011 t b )¿¿
V=GρW
hw=XDi
K w Dm
P a g e | 51
X=tube wall thickness=0.154 in
Di=tube outside diameter =2.375 in
Dm=tube mean diameter=2.22 in
Kw=Thermal conductivity=25 Btu/ hr. ft2 oF
hw=0.00066 Btu/ hr. ft2 oF
Tube Side
An equation proposed by LEVA to find heat transfer co-efficient
inside the tubes filled with catalyst particles
G = tube side mass velocity=2017 lb/hr. ft2
μ = viscosity of tube side fluid=0.073 lb/hr. ft
k = 0.0265 Btu/hr. ft oF
Dp = diameter of particle = 0.0157 ft
D = diameter of tube = 0.164 ft
On Substituting,
hi = 25.51 Btu/hr. ft2 oF
Inside dirt coefficient
From appendix table 1.3 for air
hid = 500 Btu/hr. ft2 ℉
Outside dirt coefficient
From appendix table 1.3 for water
hid = 333.33 Btu/hr. ft2 ℉
Over all H.T. Coefficient
hp d
k=3.50(
d pG
μ)e
−4.6d p
d
1U d
=1hi
do
d i
+d o
h id
+Xdo
kw dm
+ 1hod
+ 1ho
P a g e | 52
do= tube outside diameter =2.375 in
dm= tube mean diameter
UD=overall heat transfer
By putting the values
UD=16.99 Btu/hr. ft2 ℉
Area required for Heat Transfer
Q = 6.8*106 Btu/hr
LMTD = 389℉
Area required for Heat Transfer
A=1028.88 ft2 = 95.63 m2
Area Available for Heat Transfer
Length of tube = Lt = 2.5 m
Outer Dia of tube = Dot = 0.06 m
Surface area of one tube = πDotLt
= 3.14 × 0.06 ×2.5
= 0.47 m2
Total surface area available = 584 × 0.47
= 274.48 m2
So, sufficient area is available for heat transfer.
A=Q
UD LMTD
P a g e | 53
SPECIFICATION SHEET
Identification
Item
Item No.
No. required
Reactor
R-1
1
Function: Production of malice anhydride via butane
Operation: Continuous
Type: Catalytic
Multi tube, fixed bed
Chemical Reaction:
Catalyst:
Shape: Spherical
Size: 4.8 mm
Tube side: Tubes:
Material handled Feed Product No. 709
P a g e | 54
(kg/hr) (kg/hr) Length 2.438 m
C2H5OH 86326 432.58 O. D 63.5 mm
H2O 45.44 214.35 Pitch 79.37 mm pattern
CH3CHO ----- 412.8 Material of construction = copper
O2 635.28 484.96
N2 2090.82 2090.82
Temp (oC) 550 550
Shell side
ShellFluid handled = cooling water Dia = 2.66 m
Temperature 25oC to 45oC
Material of construction = Carbon steel
Heat transfer area required = 77.67 m2
6.2Design of Absorber
Absorptions
The removal of one or more component from the mixture of gases by using a
suitable solvent is second major operation of Chemical Engineering that based on mass
transfer.
In gas absorption a soluble vapours are more or less absorbed in the solvent from its
mixture with inert gas. The 'purpose of such gas scrubbing operations may be any of the
following;
a) For Separation of component having the economic value.
b) As a stage in the preparation of some compound.
c) For removing of undesired component (pollution).
Types of Absorption
P a g e | 55
1) Physical absorption,
2) Chemical Absorption.
Physical Absorption
In physical absorption mass transfer take place purely by diffusion and physical
absorption is governed by the physical equilibria.
Chemical Absorption
In this type of absorption as soon as a particular component comes in contact with
the absorbing liquid a chemical reaction take place. Then by reducing the concentration of
component in the liquid phase, which enhances the rate of diffusion.
Types of Absorbers
There are two major types of absorbers which are used for absorption purposes:
Packed column
Plate column
Comparison between Packed and Plate Column
1) The packed column provides continuous contact between vapour and liquid phases
while the plate column brings the two phases into contact on stage wise basis.
2) SCALE: For column diameter of less than approximately 3 ft. It is more usual to
employ packed towers because of high fabrication cost of small trays. But if the column is
very large then the liquid distribution is problem and large volume of packing and its
weight is problem.
3) PRESSURE DROP: Pressure drop in packed column is less than the plate column. In
plate column there is additional friction generated as the vapour passes through the liquid
on each tray. If there are large No. of Plates in the tower, this pressure drop may be quite
high and the use of packed column could effect considerable saving.
P a g e | 56
4) LIQUID HOLD UP: Because of the liquid on each plate there may be a Urge quantity
of the liquid in plate column, whereas in a packed tower the liquid flows as a thin film
over the packing.
5) SIZE AND COST: For diameters of less than 3 ft. packed tower require lower
fabrication and material costs than plate tower with regard to height, a packed column is
usually shorter than the equivalent plate column.
From the above consideration packed column is selected as the absorber, because in our
case the diameter of the column is approximately 0.8 meter which is less than 3 ft. As the
solubility is infinity so the liquid will absorb as much gases as it remain in contact with
gases so packed tower provide more contact. It is easy to operate.
PACKING
The packing is the most important component of the system. The packing provides
sufficient area for intimate contact between phases. The efficiency of the packing with
respect to both HTU and flow capacity determines to a significance extent the overall size of
the tower. The economics of the installation is therefore tied up with packing choice.
The packings are divided into those types which are dumped at random into the tower
and these which must be stacked by hand. Dumped packing consists of unit 1/4 to 2 inches
in major dimension and are used roost in the smaller columns.The units in stacked packing
are 2 to about 8 inches in size, they are used only in the larger towers.
The Principal Requirement of a Tower packing are:
1) It must be chemically inert to the fluids in the tower.
2) It must be strong without excessive weight.
3) It must contain adequate passages for both streams without excessive liquid hold up or
pressure drop.
4) It must provide good contact between liquid and gas.
5) It must be reasonable in cost.
P a g e | 57
Thus most packing are made of cheap, inert, fairly light materials such as clay, porcelain, or
graphite. Thin-walled metal rings of steel or aluminum are some limes used.
Common Packings are:
a) Berl Saddle.
b) Intalox Saddle.
c) Rasching rings.
d) Lessing rings.
e) Cross-partition rings.
f) Single spiral ring.
g) Double - Spiral ring.
h) Triple - Spiral ring.
Design Calculations of Packed Absorption Tower
98 % of the n-Butane (entering the tower at 12.948 Kgmol/h), 100 % of the Maleic
Anhydride (entering the tower at 40.388 Kgmol/h), 100 % of the Formic Acid (entering the
tower at 0.826 Kgmol/h), and 100% of the Acrylic Acid (entering the tower at 0.833
Kgmol/h) is to be absorbed. The absorption takes place at 170 kN/m2 and 373K.
Basis: 1 hour of operation
Compositions of Components in Gas Mixture at Entrance
Component Mol. Formula Mol. Wt. Kg/h Kgmol/h Mol%
Acrylic Acid C3H4O2 72 60 0.833 0.024
N-Butane C4H10 58 751 12.948 0.4
Carbon Dioxide CO2 44 2110 47.954 1.42
Carbon Monoxide CO 28 1188 42.428 1.25
Formic Acid HCOOH 46 38 0.826 0.024
Maleic Anhydride C4H2O3 98 3958 40.388 1.200
Nitrogen N2 28 69436 2480.000 73.237
P a g e | 58
Oxygen O2 32 12587 393.344 11.616
Water H2O 18 6616 367.556 10.829
Compositions of Components in Liquid Mixture at Exit
Component Mol. Formula Mol. Wt. Kg/h Kgmol/h Mol%
Acrylic Acid C3H4O2 72 60 0.833 0.04
N-Butane C4H10 58 736 12.689 0.60
Carbon Dioxide CO2 44 0 0.000 0.00
Carbon Monoxide CO 28 0.000 0.00
Formic Acid HCOOH 46 38 0.826 0.04
Maleic Acid C4H2O3 98 3958 40.388 1.91
Nitrogen N2 28 69436 0.000 0.00
Oxygen O2 32 12587 0.000 0.00
Water H2O 18 37120 2062.222 97.41
Compositions of Components in Gas Mixture at Exit
Component Mol. Formula Mol. Wt. Kg/h Kgmol/h Mol%
Acrylic Acid C3H4O2 72 0 0.000 0.00
N-Butane C4H10 58 15 0.260 0.01
Carbon Dioxide CO2 44 2110 47.954 1.62
Carbon Monoxide CO 28 1188 42.428 1.43
Formic Acid HCOOH 46 0 0.000 0.00
Maleic Anhydride C4H2O3 98 0 0.000 0.00
Nitrogen N2 28 69436 2480.000 83.66
Oxygen O2 32 12587 393.344 13.28
P a g e | 59
Water H2O 18 0 0.000 0.00
1) Selection of Solvent
The solubility data of these compounds shows that Formic acid, Acrylic and Maleic
Anhydride acid are very soluble in water. The least soluble component of the four
components, which are to be absorbed, is n-Butane. Therefore, we based the design of our
packed absorption tower on the solubility of n-Butane in water.
2) Selection of Packing
Our system, is corrosive, therefore, ceramic material is needed. The mass transfer
efficiency of Intalox Saddles is more than the Raching Rings and Berl Saddles. We have
selected this packing for the efficient operation. It is expensive than Raching Rings and Berl
Saddles. To avoid environmental pollution and to recycle n-Butane to the reactor we have to
absorb n-Butane as much as possible. Intalox Saddles (2 inch) of ceramic material is the best
choice for our required conditions.
3) Calculation of Column Diameter
Most methods for determining the size of randomly packed towers are derived from
the Sherwood correlation, which is used here to find out the diameter of the absorber. The
physical properties of gas can be taken as that of air at 60 0C and 170kN/m2 because
concentration of n-Butane is very small in gas mixture and average molecular weight of gas
mixture = 29. The flow rate of water to absorb the n- Butane has been optimized in the
context of calculation of height of absorber, which is 31230 Kg/h.
The abscissa of Fig.2.1 =( LG )¿).5
L = Flow rate of water 31230 Kg/h
G = Flow rate of gas 85956 Kg/h
ρV = Density of gas at 60 0C and 170kN/m2
ρL= Density of Water at 60 0C and 170kN/m2
ρV = PM / RT
P = 170kPs = 170kN/m2 = 1.7atm
M = 29 Kg / Kgmol
P a g e | 60
R = 0.082(atmKgmol/m3K)
T = 600C = 333K
ρV = (1.7atm* 29 Kg/Kgmol) / (0.082 atmKgmol/m3K)* 333K
= 2 Kg/m3
ρL= 988Kg/m3 at 60 0C
Therefore abscissa of the Fig.2.1¿( LG )¿).5 =0.02
For 42 mmH2O/m of packing height, from Fig.2.1
K4 = 2
From table 2.1, Fp = 22.3m-1
μL is viscosity of water at 60℃= 0.5 cp \
G* = 7.6 (Kg/m2s)
G = Flow rate of gas 85956 Kg/h
G = Flow rate of gas 23.90 Kg/s
A = Cross-sectional area of the column
A = G / G*
A = 23.90 / 7.6
= 3.14 m2
=2 m
4) Calculation of the Column Height
i. Calculations of Number of Transfer Units
The solubility data of these compounds shows that Formic acid, Acrylic and Maleic
Anhydride acid are very soluble in water. The least soluble component of the four
components, which are to be absorbed, is n-Butane. Therefore, we based the design of our
packed absorption tower on the solubility of n-Butane in water.
Assumptions:
1) Absorption takes place isothermally at 373K
G¿=¿
D = [4∗A /π ¿¿0.5
P a g e | 61
2) Carbon dioxide, Carbon monoxide, Oxygen, and Nitrogen are insoluble in water at this
temperature
3) n-Butane is our key component
Equilibrium Curve
As the concentration of solute is very small, the flow of gas and the liquid will be
essentially constant throughout the column, and the operating line as well as the equilibrium
curve for our system is straight lines. According to solubility data of n-Butane the
equilibrium curve of n-Butane-Water System (Fig.1) is straight line with a slope of 0.47 at
170 kN/m2 and 373K. Hence the equation of equilibrium curve for n-Butane-Water System
at 170 kN/m2 and 373K is:
Y * = 0.47*X----------------- (1)
Optimum Flow Rate
m = 0.47, Gm = 0.262 Kgmol/m2s then from fig.2.2
mGm/Lm 0.7 0.75 0.80 0.85 0.9
NOG 8 9 11 13 16
Opt = 0.75 which gives the optimum water flow rate Lm = 0.153 Kgmol/m2s.
Operating Line
We have to remove n-Butane from an inert gas stream of 2964 Kgmol/h in a packed
column. The inlet gas contains 0.38-mole percent n-Butane and the outlet
P a g e | 62
gas stream can contain 0.02-mole percent n-Butane. A pure inert water stream enters the
packed tower at a rate of 1735 Kg mol/h.
Taking a point in the absorption tower where Mol.fr.of n-Butane is X, Y in the liquid
and gas respectively, then by n-Butane material balance across this point and the top of the
absorption tower we have:
Inert gas flow rate G = 2964 Kgmol/h, Inert liquid flow rate L = 1735 Kg mol/h.
G (Y – Y2) = L (X – X2)
2964(Y – 0.0001) = 1735 (X – 0)
Y = 0.6*X + 0.0001-------------(2)
X = 1.7*(Y-0.0001) ------------- (3)
These two equations represent the operating line of the absorption of n-Butane.Now we
assumed different values of Y and calculated their corresponding values of X and Y * using
(3) and (1) respectively which are tabulated in the following table
Y (Assumed) X (Calculated) Y *
0.004 0.00663 0.003116
0.003513 0.00580125 0.002727
0.003025 0.0049725 0.002337
0.002538 0.00414375 0.001948
0.00205 0.003315 0.001558
0.001563 0.00248625 0.001169
0.001075 0.0016575 0.000779
0.000588 0.00082875 0.00039
1e-04 0 0
The plot of the X VS. Y graph and X VS. Y * is shown in Fig. (2). As we have plotted the
operating line and equilibrium curve on the same graph, therefore the number of transfer
units are stepped off by using McCabe-And-Thiele Method as shown in fig (2).
NOG = 9, which is the same as obtained from the Fig.2
P a g e | 63
Fig 2
CALCULATION OF HOG
For two inch Ceramic Intalox Saddles HG = 0.5, HL = 0.6 (table 2.2)
HOG = Height of transfer units, based on overall gas film, co-efficient in m
HOG = HG + (m Gm/Lm)* HL = 0.95 m
Gm = Molar flow rate of gas in lbmol / h ft 2= 0.262 Kgmol / m2s
Lm = Molar flow rate of liquid in lbmol / h ft 2
= 0.153 Kgmol / m2s
Therefore height of the Packing, Z = HOG * NOG = 0.95*9 = 8.55m
Allowance for the Liquid distribution = 1.2 m
Allowance for the Liquid distribution = 1.2 m
Hence the total height of the Column = 3.73 +1.2 +1.0 = 10.95m
Height of column can be taken as = 11 m
5) Calculation of Pressure Drop (∆P)
In Operating Region
P a g e | 64
This bed should be in two sections; thereby requiring one intermediate combined
packing support and redistribution plate. It requires one bottom support plate only:
Pressure drop due to one redistributor and one bottom plate = 2 in H2O
Total pressure drop = 8.55*3.28*0.5 + 2
= 16.022in H2O = 16.022*0.250 = 4 kN/m2
At Flooding Region
∆P = 3.0 in. of H2O / ft of packing (from table 2.1)
= 3* 8.55 * 3.28 +2= 86.13 in H2O = 86.13*0.250 = 21.53 kN/m2
6) Evaluation of Operating Conditions
Calculation of Operating Velocity
Reading the abscissa of Fig.2.3 at value
The abscissa of Fig.2.3 = = 0.02
The value of ordinate = 0.035
Therefore, operating velocity for the gas from:
G 2 Fμ L 0.1/ ρV( ρL ρV )gc = 0.035,
G = 5 ft/s = 1.52 m/s
Calculation of Flooding Velocity
Reading the abscissa of Fig.2.3 at value
The abscissa of Fig.1=( LG )¿).5 =0.02
Ordinate for flooding line = 0.19 (for dumped packings for the same abscissa)
Therefore, flooding velocity for the gas from:
G 2 Fμ L 0.1/ ρV( ρL ρV )gc = 0.19,
G = 9.25 ft/s = 2.82 m/s
P a g e | 65
Operating velocity as %age of the flooding velocity
= (1.52/2.82)*100 = 54 %.
Calculation of Percent Flooding of Velocity
Reading the abscissa of Fig.2.3 at value
The abscissa of Fig.5
( LG )¿).5 = 0.02
G 2 Fμ L 0.1/ ρV( ρL ρV )gc = 0.035,
Ordinate for flooding line = 0.19 (for dumped packings for the same abscissa)
% Flooding = [0.035/0.19] 100 =18.42%
Pressure drop at flooding region = 21.53 kN/m2
Pressure drop at operating region = 4 kN/m2
Therefore, % flooding of liquid = (4 /21.53)*100 = 18.6 %
Calculation of Liquid Hold up and Support Load
Liquid hold up (htw):
htw = 0.0004(L / dp) 0.6
L = superficial mass flow rate of water, lb/hr.ft2 = 2027 lb/hr.s
dp = Equivalent dia of the packing, ft from table 2.3 = 0.115 ft
Therefore, the liquid hold up is:
htw = 0.14 ft3 of water / ft3 of column volume
Calculation of Number of Streams for Liquid Distribution at the Top of
Packing
Number of liquid distribution streams at the top of the packing
D = Diameter of the absorption column in inches = 59inch
Ns= (D / 6) 2
P a g e | 66
Putting values in above equations, we get, Ns = 100
Caluclation of Wetting Rate (LP)
Lp = Liquid flow rate per unit cross-sectional area / Specific area of packing
= 2.80*10-3 m3/m2s
Sp.area of packing from table 4 = 11 m2/m3,
Lp = 2.76*10-3/11 = 2.5* 10 –4 (m3 / m s)
SPECIFICATION SHEET
Identification
Item: Packed Absorption Column
Item No.T-101
No. required 01
Function: To absorb n-Butane, maleic anhydride, formic acid and acrylic acid in water.
Operation: Continuous
P a g e | 67
Entering gas Exit gas Liquid Liquid leaving
Kg/hr(Kgmol/hr) Kg/hr(Kgmol/hr) entering Kg/hr(Kgmol/hr)
Kg/hr
96744(3386) 82992(2964) 31230(1735) 123935(2117)
Design Data
No. of transfer units = 9
Height of transfer units = 0.95 m
Height of packing section = 8.55 m)
Total height of column = 11m
Inside diameter = 2 m
Flooding velocity = 9.25m/sec
Maximum allowable gas velocity = 5.0 m/sec
Pressure drop = 42 mmH2O/m of packing
Internals
Size and type = 50.8 mm, Intalox saddle
Material of packing: Ceramic
Method of packing: (wet) float into tower filled with water.
Packing arrangement: dumped
Type of packing support: simple grid & perforated support
6.3 Distillation Column
In industry it is common practice to separate a liquid mixture by distillating the
component, which have lover boiling points when they are in pure
condition from those having higher boiling points. This process is accomplished by partial
vaporization and subsequent condensation.
Here in our project “production of Maleic Anhydride from n-butane”
Maliec anhydride is separated from water.
P a g e | 68
The choice between plate and packed column
Vapour liquid mass transfer operation may be carried either in plate column or packed
column. These two types of operations are quite different. A selection scheme considering
the factors under four headings.
i) Factors that depend on the system i.e. Scale, foaming, fouling factors, corrosive systems,
heat evolution, pressure drop, liquid holdup.
ii) Factors that depend on the fluid flow moment.
iii) Factors that depends upon the physical characteristics of the column and its internals i.e.
Maintenance, weight, side stream, size and cost.
iv) Factors that depend upon mode of operation i.e. Batch distillation, continuous
distillation, turndown, intermittent distillation.
The relative merits of plate over packed column are as follows:
i) Plate column are designed to handle wide range of liquid flow rates without flooding.
ii) If a system contains solid contents, it will be handled in plate column, because solid will
accumulate in the voids and coating the packing materials and making it ineffective.
iii) Dispersion difficulties are handled in plate column when flow rate of liquid are low as
compared to gases.
iv) For large column heights, weight of the packed column is more than plate column.
v) If periodic cleaning is required, main holes will be provided for cleaning. In packed
columns packing must be removed before cleaning.
vi) For non-foaming systems the plate column are preferred.
vii) Design information for plate column are more readily available and more reliable that
that for packed column.
viii) Inter stage cooling can be provide to remove heat of reaction or solution.
ix) When temperature change is involved, packing may be damaged.
P a g e | 69
For particular process, “Maliec Anhydride and water system”, we have
selected plate column due to:
i) System is non-foaming.
ii) Temperature change is high (75o c).
iii) The column diameter is greater than 0.6 m
iv) The vapour flow rate is high as compared to liquid flow rate so if packed column is used
due to low liquid flow rate liquid and vapour contact would not be good so efficiency will
decrease.
CHOICE OF PLATE TYPES
There are four main tray types, the bubble cap, sieve tray, ballast or valve trays and the
counter flow trays. I have selected sieve tray because:
i) They are lighter in weight, less expensive. It is easier and cheaper to install.
ii) Pressure drop is low as compared to bubble cap trays.
iii) Peak efficiency is generally high.
iv) Maintenance cost is reduced due to the ease of cleaning.
v) Since sieve trays rely on vapour flow rate, the vapour flow rate is high so no weeping
occurs.
P a g e | 70
DISTILLATION COLUMN DESIGN
Feed Composition & Flow Rates (F)
Component Mass Flow Molar Flow Mol. Fraction
Rate Rate (Kmol/hr)
(Kg/hr)
H2O 1531 85.056 0.677
Maleic Anhydride 3957.24 40.38 0.321
Butane 1..914 0.033 .000267(negligible)
Formic acid .0228 0.0228 0.000182(negligible)
Acrylic acid 5.472 0.076 0.000607(negligible)
5495.6 125.5 1.00
Top Product Composition and Flow Rate(D)
Component Mass Flow Molar Flow Mol. Fraction
Rate Rate(Kmol/hr)
Kg/hr
H2O 1519 84.39 0.979
Maleic Anhydride 168.7 1.722 0.0199
Butane 1.931 0.0333 0.000389(negligible)
P a g e | 71
Formic acid 1.012 0.022 0.00026(negligible)
Acrylic acid 2.736 0.038 0.000442(negligible)
Total 1693.4 86.2 1.00
Bottom Product Composition & Flow Rates (B)
Component Mass Flow Molar Flow Mol. Fraction
Rate Rate(Kmol/hr)
Kg/hr
H2O 14.36 0.789 0.0199
Maleic Anhydride 3786.72 38.64 0.979
Butane 0 0 0
Formic acid 0.0211 0.00046 0.0000116(negligible)
Acrylic acid 2.736 0.038 0.000965(negligible)
Total 3803.83 39.47 1.00
ASSUMPTION
Binary distillation (H2O & maleic anhydride)
Ideal gas behaviour of vapours.
1. BOTTOM TEMPERATURE (TB) Bubble point calculations:-
PT = 1.2atm, T=185 oC (Assume)
Components Xb=Xi V.P(psia) Ki=V.P/PT Yi= KiXi
Maleic anhydride 0.979 11.76 0.8 0.7832
Water 0.0199 1.80 12.24 0.2435
Total 1.00 1.02
2.Top Temperature:-
Dew Point Temperature
PT = 1.2atm
TD =110 oC (Assume)
P a g e | 72
Components Yi=XF V.P(psia) Ki=V.P/PT Xi= Yi/ Ki
Maleic anhydride 0.0199 0.7 0.048 0.41
Water 0.979 23 1.56 0.615
Total 1.00 1.025
3.Temperature of Feed(TF):-
TF =160 oC
4. Feed Conditions:-
Dew point calculations:-
T=160.5℃
Components XF=Yi V.P(psia) Ki=V.P/PT Xi= Yi/Ki
Water 0.677 100 6.8 0.0929
Maleic anhydride 0.322 5.17 0.325 0.91
Total 1.00 1.0029
Since the dew point of feed is same as feed temperature so feed is at its dew point.
5. Calculation for α (Relative Volatility)
TF = Feed Temperature (oC) =160
Light key component (LK) =water
Heavy key component (HK) =malice anhydride
Component Top Bottom Average
Ki DiKi/KHK Ki BiKi/KHK α
Maleic 0.048 1 0.8 1 1
Anhydride
Water 1.56 32 12.24 15 21.7
6.Minimum Number of Plates (Nm)
P a g e | 73
Fensky Equation
S = still, (αAB)av = α = 21.7
Nm = 3
7.Caluclation of Rm(Minimum Reflux Ratio)
As feed is at its dew point so q = 0
By trial θ = 12.3
α A
xfA
α
B x
fB1 q
α A θ α B θ
P a g e | 74
Using eq. of min. reflux ratio
α A
xfA
α B
xfB R 1
α A θ α B θm
A = water, LK B = malice anhydride, HK
D = distillate
XfA=mol fraction of component corresponding to light key in feed.
XfB=mol fraction of component corresponding to heavy key in feed.
Rm = 1.26
8. Reflux Ratio (R)
R=1.25(Rm)
=1.57
9. Actual Number of theorical stages
From “Kirk bride” relation
N=8
10. Column Efficiency
Where
μ1=viscosity of liquid at mean tower temperature
μw=viscosity of water at 293 k
Xf = mol fraction of components in feed
N−Nm
N+1=0.75 [1−( R−Rm
R+1
0.566)]
E=0.17−0.616 log10 ∑[ x f ( μ1
μw)]
P a g e | 75
Mean tower temperature = 147.5 0C= 420.5 K
μ1= 0.174 cp
μw= 0.83 cp
Xf = 0.677
For maleic anhydride
μ1= 0.485 cp
μw= 0.83 cp
xf = 0.321
On Calculating
E = 0.48
11. ACTUAL NUMBER OF PLATES
Taking reboiler as a stage.
where
Na = actual number of plates
N = theoretical plates
E = efficiency
Na = 15
12.Feed Plate Location
Where
Nr = number of stages above the feed, including any partial condenser,
Ns = number of stages below the feed, including the reboiler,
B = molar flow bottom product,
D =molar flow top product,
Na=N−1
E
P a g e | 76
xf,HK = concentration of the heavy key in the feed,
xf,LK =concentration of the light key in the feed,
xd,HK = concentration of the heavy key in the top product,
xb,LK = concentration of the light key if in the bottom product.
B=39.47 Kmol/hr
D=86.2Kmol/hr
ND/NB= 0.9928
Na-NB=0.9928NB
NB=8
ND=7
So feed enters the column at 8th stage.
13. Column Pressure Drop
Assume 170 mm. water pressure drop per plate
∆Pt = 9.81ht *10-3 ρL Na
Where
∆Pt = total pressure drop (pa)
ht =Total plate pressure drop(mm liquid)
ρL = Density of liquid(H2O) at 25 o C
Na =actual no. of plates
By putting Values in above eq.
∆Pt = 25015.5 pa
Top pressure = 121.6*103 pa
Estimated bottom pressure = 146615.5 pa=1.44 atm
14. Liquid Vapour Flow Factor
Where
FLV =( Lm
T m)¿
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Lm=liquid flow rate (kg/sec)
Vm=vapour flow rate (kg/sec)
For top:-
Balance around condenser
Vn = Ln+ D
Vn = 221.5 kmol/hr
=1.21 kg /sec
Ttop=110℃
Av. Mol. Wt.=19.6 kg/k.mol
ρ v= 0.75kg/m3
ρL= 963.95 kg/m3 (From Perry)
So
FLVtop=0.016
For bottom:-
Balance around reboiler
Lm = Vm +B
135.3=Vm+39.47
Vm = 96 Kmol/hr
=0.422Kg/sec
Tbottom = 185o C
Av.mol wt=96.3
ρ v=3.7 Kg/m3
ρL=1302.2 Kg/m3 (table 3.1)
On Substituting,
FLV bottom =0.075
15. FLOODING VELOCITIES:-
U f=K1 √ ρL−¿ ρV
ρV
¿
P a g e | 78
U f= flooding vapour velocity
K1* = constant from fig 3.1
Whereσ =surface tension
By “sudgenparachor” method
where
σ = surface tension
pCh= sudgen’sparachors constant
M = mol.wt
At top:-
From fig 3.1 ,
K1* = 0.095
pCh= 54.2
σ top = 50 mJ/m2 = 5*10 -2 N/m
K1 = 0.114
Uf = 4.08 m/s
At bottom:-
From fig 3.1,
K1* = 0.090
pCh = 216.6
σ bottom = 21.7*10 -3 N/m
K1 = 0.0912
Uf = 2.58 m/s
Designing at 85% flooding at maximum flow rate
Corrected K1 =K1*¿
σ=¿
P a g e | 79
Top UV = 0.85 * Uf = 3.47 m/s
Bottom UV = 0.85 * Uf = 2.2 m/s
16.Maximum Volumetric Flow Rate :-
Top:-
Vn = 221.5 kmol /hr =0.0615 Kmol /sec
Max Volumetric flow rate = Vn ×Μ.wt /ρV
=1.6m3/sec
Bottom:-
Vm = 96 kmol /hr =0.027 Kmol /sec
Max Volumetric flow rate = Vm ×Μ.wt / ρV
=0.72 m3/sec
Net Area Required:-
A top = 0.51m2
A bottom =0.32 m2
Column Cross-Sectional Area :-
Taking down comer area as 12% of total
ACTop = Α T op/0.88
= 0.51 m2
AC Bottom = Abottom/ 0.88
=0.36 m2
19. Column Diameter
A=max . vol flow rateUV
P a g e | 80
DTop = 0.86 m
Dbottom = 0.68m
20. Liquid Flow Pattern
Where
Ln =Liquid Flow rate (k mol/hr)
ρL= Density of Liquid (Kg/m3)
On Substituting,
Ln =135.3 k mol/hr
ρL=963.95 Kg/m3
M=19.6
So max.Volumetric Flow rate = 2.78* 10-3 m3/sec
From fig. 3.2 it is clear that cross flow single Plate is used.
21. Provisional Plate Designing
Sieve plate is selected
Column Dia = Dc = 0.86 m
Column Area = Ac = 0.51 m2
Downcomer Area = Ad = 0.12 Ac = 0.0612m2 (12% of Ac)
Net Area = An = Ac – Ad = 0.448 m2
Active Area = Aa = Ac – 2Ad = 0.387 m2
D=√ 4 AC
π
Max. Volumetric flow Rate=Ln× M . Wt
3600 × ρL
P a g e | 81
Ah = hole area (total) = Aa 0.1 = 0.0387 m2 (10% of Aa)
From fig (3.3)
lw /Dc = 0.76
lw = weir length
lw = 0.654m
Take weir height = hw = 50 mm
Hole diameter = dh = 5mm
Plate thickness = 5 mm
22. Check Weeping :-
Where
LM =Liquid Flow rate below feed plate (k mol/hr)
On Substituting,
LM =135.3 k mol/hr
M. wt =96.3
Max. Liquid flow Rate = 3.62 kg/sec
Max. Liquid flow Rate at 70% turndown = 0.7*3.62 = 2.53 kg/sec
Weir Liquid Crest:-
Where
lw=weir length
how= weir crest, (mm liquid)
Lw= liquid flow rate, kg/sec
Max. Volumetric flow Rate=Ln× M . Wt
3600 × ρL
how=750¿
P a g e | 82
ρL=liquid density at bottom kg/m3
For minimum
On Substituting,
lw=0.654m
Lw= 2.53 ,kg/sec
ρL=1302.2 kg/m3
so ,
how= 15.5, (mm liquid)
For maximum
Substitute,
lw=0.654m
Lw= 3.62, kg/sec
ρL =1302.2 kg/m3
so ,
how= 19.7, (mm liquid)
At minimum rate
hw+how = 65.5 mm liquid
how= 15.5, (mm liquid)
23. Weep Point:
a) Minimum vapour velocity through holes:
ρ v= vap. density at base, kg/m3
dh= hole dia ,mm
U h=[k2−0.90 (25.4−dh)]
¿¿
P a g e | 83
k 2 = const. Fig. 3.4
put
ρ v= 3.7 kg/m3
dh = 5 mm
k 2 = 30.3
so
U h= 6.2 m/s
b) Actual minimum vapour flow velocity:
=0.7×0.702/0.0387
=12.7 m/sec
Since the total minimum vapour rate is above weep point. so no weeping
occurs.
24. Plate Pressure Drop:-
a) Maximum vapour velocity through holes:-
=1.6/0.0387
=41.3 m/sec
b) Pressure Drop Through Dry plate:
Where,
Co = const. from fig 3.5
U a=min. vap flow rate
Ah
hd=51¿
P a g e | 84
At plate thickness/hole dia=5mm/5mm=1 & Ab
Aa
=¿0.1
Co= 0.87
Put
ρV = 0.75 kg/m3
ρL= 963.95 kg/m3
hd=89 mmliq
c) Residual head:
=12.96 mm liq
d)Total pressure drop:-
ht = hd + (hw + how) + hr
Where
hd =pressure drop through dry plate
hw =weir height
how =weir liquid crest (max)
hr =residual head
putting values
ht =171.6 mmliq
This is close to the assumed value of pressure drop, so it is accepted.
25. Down Comer Backup:-
a) Down comer pressure loss:-
Take
hap= hw – 10
Where hw = weir height
hr=125× 103
ρL
P a g e | 85
hap = 40mm
b) Area Under apron:-
Aap = hap lw
Where
hap = height of bottom edge of apron above plate
Lw = weir length
So Aap = 0.026 m2
b) Head loss in downcomer :-
Where
hdc=head loss in down comer (mm)
Lwd= Liquid flow rate in down comer
Am = either the down comer or Area for Clearance Area under down comer Aap
whichever is small
Put
Lwd= 3.62 kg/s
ρL= 963.95 kg/m3
Am = 0.0612m
So
hdc= 0.625 mm
c) Backup in downcomer;-
hbc = hdc + (hw + how max) + h t
Put
hw = 50mm
hdc =0.625 mm
hdc=166¿
P a g e | 86
how max =19.7 mm
ht =190.6 mm
so,
hbc =261 mm = 0.261 m
0.261 < ½ ( plate spacing + weir height)
0.261 < 0.275
so our plate spacing 0.5 m is acceptable
26. Down Comer Residence Time;-
Where
t r= down comer residence time sec
hbc= dead liquid backup m
Lwd= liquid flow rate in Down -comer
ρL= liquid density
hbc = 0.261 m
Lwd= 3.62 kg/s
ρL= 963.95 kg/m3
So
t r= 4.25 sec (>3 (satisfactory))
27. CHECK ENTRAINMENT;-
Where
Un = actual velocity based upon net area
t r=[Ad hbc ρL
Lwd
]
% flooding=[U n
U f
¿
P a g e | 87
Uf = flooding Velocity
put values
Max.volumetric Flow rate =1.6
An = 0.51
Un= 3.14 m/s
Since Uf = 4.08 m/s
% flooding = 77%
from Fig. 3.6 at Flv = 0.016
percent entrainment i.e. = 0.097
28. Number of Holes
Dia of hole ( D) = 50 mm = 0.05 m
Area of Single whole ( A1 ) = π /4D2 = 1.96 * 10 -5 m 2
Total no. of Holes = Ah / A1 = 1975
29. Height of Distillation Column
No. of Plates = 15
Tray Spacing = 0.5 m
Distance between 15 plates = 15 * 0.5 = 7.5 m
Take
top Clearance = 0.5 m
Bottom Clearance = 0.5 m
Plate Thickness = 5mm / plate = 5*10 -3 m / plate
Total thickness of plates = 5* 10 -3 * 15
Un= max.Volumetric flow rate/net area required
P a g e | 88
= 0.075 m
= 75 mm
Total column height = 7.5 m + 0.5 +0.5 m +0.075m = 8.6 m
30. Mechanical Design
Shell material = carbon steel
Sieve plate material = stainless steel 316
Operating pressure =1.2 atm
Taking design pressure 40% more than operating pressure then
Design pressure = 1.68 atm
= 0.168 MPa
shell diameter =0.86 m
shell Height = 8.6 m
Shell thickness =
Where
P= design pressure =0.168 MPa
j= joint efficiency = 0.85
C = corrosion allowance for carbon steel = 2mm = 2*10-3 m/yr
f = allowable stress = 96.26 MPa
Di = internal diameter
ts = 0.046 m = 46 mm
SPECIFICATION SHEET
Identification:
Item Distillation column
Item No. T-102
No. required 1
Tray type Sieve tray
t s=( P2 fj−P )× Di+C
P a g e | 89
Function: separation of maleic anhydride from water
Operation: Continuous
Material handled
Feed Top Bottom
Quantity 125.5 Kgmol/hr 86.2 Kgmol/hr 39.47 Kgmol/hr
5495.6 Kg/hr 1693.4 Kg/hr 3803.83Kg/hr
Composition of 32.2 % 2% 98 %
Maleic Anhydride
Temperature 160 oC 110 o C 185 oC
Design Data
No. of trays = 15 Pressure = 1.2 atm Height of column = 8.6 m
Diameter of column = 0.86 m
hole area/active area = 0.10
weir length = 0.654 m
weir height = 50 mm
reflux ratio = 1.57:1
Hole size = 5 mm
Tray thickness = 5 mm
Flooding = 77 %
tray spacing = 0.5 m No. of holes = 1975
P a g e | 90
7.Instrumentation & Process Control7.1 Instruments
Instruments are provide to monitor the key process variables during plant
operation. They may be incorporated in automatic control loops or used for the manual
monitoring of the process operation. They may also be part of an automatic computer data
logging system. Instruments monitoring critical process variables will be fitted with
automatic alarms to alert the operators to critical and hazardous situations.
It is desirable that the process variable to be monitored be measured directly;
often, however, this is impractical and some dependent variable that is easier to measure, is
monitored in its place. For example, in the control of distillation columns the continuous on-
line, analysis of the over-head product is desirable but difficult and expensive to achieve
reliably, so temperature is often monitored as an indication of composition. The temperature
instrument may form part of a control loop controlling, say, reflux flow; with the
composition of the overheads checked frequently by sampling and laboratory analysis.
7.2 Instrumentation And Control Objectives
The primary objective of the designer when specifying instrumentation and control schemes
are:
1) Safer Plant Operation
a) To keep the process variables within known safe operating limits.
b) To detect dangerous situations as they develop and to provide alarms and automatic shut-
down systems.
c) To provide inter locks and alarms to prevent dangerous operating procedures.
2) Production Rate
To achieve the design product output.
3) Product Quality
To maintain the product composition within the specified quality standards.
4) Cost
P a g e | 91
To operate at the lowest production cost, commensurate with the other objectives.
These are not separate objectives and must be considered together. The order in
which they are listed is not meant to imply the precedence of any objective over another,
other than that of putting safety first. Product quality, production rate and the cost of
production will be dependent on sales requirements. For example, it may be a better strategy
to produce a better quality product at a higher cost.
In a typical chemical processing plant these objectives are achieved by a
combination of automatic control, manual monitoring and laboratory analysis.
7.3 Components of Control System
Process
Any operation or series of operations that produces a desired final result is a
process. In this discussion the process is the cracking of naphtha.
Measuring Means
Of all the parts of the control system the measuring element is perhaps the most
important. If measurements are not made properly the remainder of the system cannot
operate satisfactorily. The measured available is dozen to represent the desired condition in
the process.
ANALYSIS OF MEASUREMENT VARIABLES TO BE MEASURED
a) Pressure measurements
b) Temperature measurements
c) Flow Rate measurements
d) Level measurements
Variables to be Recorded
Indicated temperature, composition, pressure, etc.
Controller
The controller is the mechanism that responds to any error indicated by the error
detecting mechanism. The output of the controller is some predetermined function of the
error.In the controller there is also and error-detecting mechanism which compares the
P a g e | 92
measured variables with the desired value of the measured variable, the difference being the
error.
Final Control Element
The final control element. receives the signal from the controller and by some
predetermined relationships changes the energy input to the process.
7.5 Classification of Controller
In general the process controllers can be classified as:
a) Pneumatic controllers
b) Electronic controllers
c) Hydraulic controllers
In the ethylene manufacturing from naphtha the controller and the final control element may
be pneumatically operated due to the following reasons:
i) The pneumatic controller is vary rugged and almost free of maintenance. The maintenance
men have not had sufficient training and background in electronics, so basically pneumatic
equipment is simple.
ii) The pneumatic controller appears to be safer in a potentially explosive atmosphere which
is often present in the petro-chemical industry.
iii) Transmission distances are short. Pneumatic and electronic transmission system are
generally equal upto about 250 to 300 feet. Above this distance, electronic systems begin to
offer savings.
7.6 Modes of Control
The various type of control are called "modes" and they determine the type of
response obtained. In other words these describe the action of the controller that is the
relationship of output signal to the input or error signal. It must be noted that it is error that
actuates the controller. The four basic modes of control are:
i) On-off Control
P a g e | 93
ii) Integral Control
iii) Proportional Control
iv) Rate or Derivative Control
In industry purely integral, proportional or derivative modes seldom occur alone in
the control system.
The On-off controller in the controller with very high gain. In this case the error
signal at once off the valve or any other parameter upon which it sits or completely sets the
system.
7.7 Alarms and Safety Trips and Interlocks
Alarms are used to alert operators of serious, and potentially hazardous, deviations
in process conditions. Key instruments are fitted with switches and relays to operate audible
and visual alarms on the control panels.
The basic components of an automatic trip systems are:
i) A sensor to monitor the control variable and provide an output signal when a preset valve
is exceeded (the instrument).
ii) A link to transfer the signal to the actuator usually consisting of a system of pneumatic or
electric relays.
iii) An actuator to carry out the required action; close or open a valve, switch off a motor. -
A safety trip can be incorporated in control loop; as shown in figure . In this system the
high-temperature alarm operates a solenoid valve, releasing the air on the pneumatic
activator closing the valve on high temperature.
Interlocks
Where it is necessary to follow the fixed sequence of operations for example,
during a plant start-up and shut-down, or in batch operations-inter-locks are included to
prevent operators departed from the required sequence. They may be incorporated in the
control system design, as pneumatic and electric relays or may be mechanical interlocks.
P a g e | 94
7.8 Different Type of Controllers
Flow Controllers
These are used to control feed rate into a process unit. Orifice plates are by far the
most type of flow rate sensor. Normally, orifice plates are designed to give pressure drops in
the range of 20 to 200inch of water. Venture tubes and turbine meters are also used.
Temperature Controller
Thermocouples are the most commonly used temperature sensing devices. The
two dissimilar wires produce a millivolt emf that varies with the "hot-junction"temperature.
Iron constrictant thermocouples are commonly used over the 0 to 1300°F temperature range.
Pressure Controller
Bourdon tubes, bellows, and diaphragms are used to sense pressure and differential
pressure. For example, in a mechanical system the process pressure force is balanced by the
movement of a spring. The spring position can be related to process pressure.
Level Controller
Liquid levels are detected in a variety of ways. The three most common are:
Following the position of a float, that is lighter them the fluid.
Measuring the apparent weight of a heavy cylinder as it buoyed up more or less by
the liquid (these are called displacement meters).
Measuring the difference in static pressure between two fixed elevations, one in the
vapour above the liquid and the other under the liquid surface. The differential
pressure between the two level taps is directly related to the liquid level in the vessel.
Transmitter
The transmitter is the interface between the process and its control system. The job
of the transmitter, is to convert the sensor signal (millivolts, mechanical movement, pressure
differential, etc.) into a control signal 3 to 15 psig air-pressure signal, 1 to 5 or 10 to 50 milli
ampere electrical signal, etc.
P a g e | 95
Control Valves
The interface with the process at the other end of the control loop is made by the final
control element is an automatic control valve which throttles the flow of a stem that open or
closes an orifice opening as the stem is raised or lowered. The stem is attached to a
diaphragm that is driven by changing air-pressure above the diaphragm. The force of the air
pressure is opposed by a spring.
7.9 Control Schemes of Distillation Column
GENERAL CONSIDERATION
Objectives
In distillation column control any of following may be the goals to achieve
1. Over head composition.
2. Bottom composition
3. Constant over head product rate. .
4. Constant bottom product rate.
Manipulated Variables
Any one or any combination of following may be the manipulated variables
1. Steam flow rate to reboiler.
2. Reflux rate.
3. Overhead product withdrawn rate.
4. Bottom product withdrawn rate
5. Water flow rate to condenser.
7.10 Loads or Disturbances
Following are typical disturbances
1. Flow rate of feed
2. Composition of feed.
3. Temperature of feed.
P a g e | 96
4. Pressure drop of steam across reboiler
5. Inlet temperature of water for condenser.
7.11 Control Scheme
Overhead product rate is fixed and any change in feed rate must be absorbed by
changing bottom product rate. The change in product rate is accomplished by direct level
control of the reboiler if the stream rate is fixed feed rate increases then vapor rate is
approximately constant & the internal reflux flows must increase.
ADVANTAGE
Since an increase in feed rate increase reflux rate with vapor rate being approximately
constant, then purity of top product increases.
DISADVANTAGE
The overhead reflux change depends on the dynamics of level control system that adjusts it.
Figure: Control scheme
P a g e | 97
8.Materials of Construction Any engineering design, particularly for a chemical process plant, is only useful
when it can be translated into reality by using available materials of construction combined
with the appropriate techniques of fabrication can play a vital role in the success or failure
of a new chemical plant.
8.1 Corrosion In Brewery Industry
Breweries are unique in many aspects in the food-processing industry. The product
and its production as well as cleaning procedure, storage, and bottling, all use great
quantities of water. They require a large amount of tankage and extensive hot water
facilities. Furthermore, the product is an acidic liquid that is aggressive to low-carbon steel.
This is further complicated that the presence of iron ions in the product drastically affects its
shelf life.
Wet, damp, and high-humidity conditions all contribute to plant corrosion and
premature equipment failure if not properly treated. These factors make the typical brewery
a challenge to the corrosion engineer. A brewery materials engineer must be familiar with
the materials of construction for all of this equipment and must also be aware of diverse
corrosion control techniques involving coatings, metals, cathodic protection, plastics and
even the use of inhibitors.
8.2 Corrosion Control Methods
As in any other industry there are always several ways to solve a given material
problem in the brewery. The task of the materials (corrosion) engineer is to sort out the
available choices and to arrive at the most cost-effective solution to the problem.
Traditionally, brew masters, who at one time exercised, employed set conditions for
plant equipment, such as wood with wax linings (tanks with slotted or perforated false
bottoms used for filtering clear liquid from the grain mash) for fermentation and storage,
copper for kettles and lanter tubes, and low carbon steel for pasteurization.
In our plant corrosion is controlled by coating the equipments with paints.
P a g e | 98
8.3Important Material Available
Material of construction may be divided into two general classification of metals
and non-metals. Pure metals and metallic alloys are included under the first classification.
1) Iron and Steel
Although many materials have greater corrosion resistance than iron and steel cost
aspects favor the use of iron and steel. As a result they are often used as a material of
construction when it is known that some corrosion will occur. If this is done the presence of
iron salts and discoloration in the product can be expected and periodic replacement of the
equipment should be anticipated. In general, cost of iron and carbon steel exhibit about the
some corrosion resistance. They are not suitable for use with dilute acids, but can be used
with many strong acids; since a protective coating composed of corrosion products forms on
the metal surface.
2) Stainless Steel
There are more than 100 different types of stainless steels. The main reason for
the existence of stainless steels in their resistance to corrosion. Chromium is the main
alloying element, and the steel should contain at least 11%. Chromium is a reactive element
but it and its alloys passivity and exhibit excellent resistance to many environments. A large
number of steels are available. So stainless steel contains chromium, nickel, iron, and also
containing small amount of other essential properties. They have excellent corrosion
resistance and heat-resistance properties. Most of the brewery equipment currently being
installed is fabricated from A1S1 type 304 stainless steel.
3) Nickel and its Alloy
Nickel exhibits high corrosion resistance to most alkalies.' Nickel-clad steel is
used extensively for equipment in the production of caustic soda and alkalies. The strength
and hardness of nickel is almost as great as carbon steel. In general, oxidizing conditions
promote the corrosion of nickel, and reducing conditions retard it. Monel, an alloy of nickel
containing 67% nickel and 30% copper is often used in food industries. This alloy is
stronger than nickel and has better corrosion resistance properties than either copper or
nickel.
P a g e | 99
4) Copper
It has been the traditional metal in breweries for centuries, but with the
advent of new alkaline cleaner, some corrosion problems have occurred. Copper and copper
base alloys are used in the formation of heat exchanger tubing, piping, fittings, etc.
Although the corrosion rates are comparatively high. In the range from room temperature
upto 100°C, the corrosion rate of copper is comparatively small. However, the corrosion
rate of 100°C is about five times that which takes place at room temperature.
5) Aluminium
The lightness and relative ease of fabrication of aluminum and its alloys are
factors favoring the use of these materials. Aluminium resists attack by acids because a
surface film of inert hydrated aluminium oxide is formed. This film adheres to the surface
and offers good protection unless materials which can remove the oxide, such as hydrogen
acids or alkalies are present.
6) Land
Pure lead has low creep fatigue resistance, but. its physical properties can
be improved by the addition of small amounts of silver, copper, antimony or tellurium.
Lead-clad equipment is in common use in many chemical plants. Lead shows good
resistance to sulfuric acid and phosphoric acid but it is susceptible to attack by acetic acid
and nitric acid.
7) Hastelloy
The beneficial effects of nickel, chromium, and molybdenum arc combined
in Hastelloy C to give an expensive but highly corrosion-resistant material. A typical
analysis of this shows 56% nickel, 17 molybdenum, 16% chromium, 5% iron and 4%
tungsten with manganese, silicon, carbon, phosphorus, and sulfur making up the balance.
Hastelloy C is used where structural strength and good corrosion resistance are necessary
under conditions of high temperature. The material can be machined and is easily
fabricated.
P a g e | 100
8) Coatings
Breweries are large consumer of quality coatings, not only for tankage but also for
structural steel, flooring and other working areas. The coating used range from high heat
silicones for stacks to special super resistant grouts for floor pavers.
9) Floor Materials
Considerable giazod tile is used in breweries and special expoxies with good
adhesion to very smooth surfaces have employed to coat glazed ceramic tile in order to
prevent crazing (cracking).Bacterial contamination deep in the pores of the concrete is a
common occurrence. If floors are not properly sealed, corrosion of concrete rebars and
structural steel can result, with eventual cracking and spalling of concrete.
10) Plastics
For corrosion control point of view, plastics materials are very useful,
therefore they have found application in breweries, water treatment tanks, acid storage,
roofing, and gutters are application for plastics that are common to most industrial activity.
Fiberglass and polyvinyl chloride are among the plastics that have been employed. Small
polypropylene tanks for yeast culture and other specialty service have some record of use.
8.4 Sulfuric Acid Handling Materials
Mild steel is widely used for the handling of sulfuric acid in concentration
over 70% storage tanks, pipelines, tank cars, and shipping drums made of steel are very
common for 78% (60 B6), 93% (66Be), 98% and stronger acids such as oleum. Pumps and
valves are often made of high-alloy material such as type 316 stainless steel because of
erosion corrosion of steel. Much of the equipments are made of mild steel. Steel is attacked
rapidly by more dilute sulfuric acids. Most of the, tests were made on ordinary steel of 0.2%
carbon.
Mild steel would not be generally suitable in concentration below 65% at
any temperature. Above 70% concentration this type of steel can be used, depending on
temperature.
P a g e | 101
Mild steel is also generally unsatisfactory for handling suifuric acid from 100
to 101 with the oleum range.
Although the stainless steel may be used safely in contact with 80 to 100%
sulfuric acid at ambient temperature (carbon steel is ordinarily used in this range), they are
attacked slightly high temperature. One to 5% sulfuric acid at ambient temperature overtone
should not be stored molybdenum-free stainless steel. Type 316 may be used for this
purpose.
*Note: Baume Scale: [A scale of relative density (specific gravity) of liquids, Named after
A. Baurn6 (1728-1804). Degrees Baume = 144.3 (r.d.- l)r.d.]
8.5 Recommended Materials Of Construction
Maliec anhydride when pure shows corrosive action upto its boiling point
temperature. Therefore, special material of construction used in the production and handling
of maliec anhydride. Pure maliec anhydride is probably less corrosive toward stainless
steel .
Although many materials have greater corrosion resistance than carbon steel,
cost aspects favor the use of carbon steel. As a result they are often used as material of
construction when it is known that some corrosion will. All the major equipments of
"industrial malice anhydride" is recommended to be manufactured by carbon steel; some
equipments where conc. H2SO4 and dilute acid used stainless steel 304 or 316 are used
otherwise lining of corrosion resistance material can be used. So recommended material of
construction is stainless steel.
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9. Plant Layout
Plant layout is the functional arrangement of machinery and equipment in a
existing plant. Plant layout may be defined as the floor plan for determining and
arranging the desired equipment of a plant, in the one best place, to permit the quickest
flow of materials at lowest cost and least amount of handling in processing the raw
material from the receipt of raw material to the shipment of finished products.
The material handling planned in the layout begins at the receiving point,
where the material arrives as raw material, then continuous progressively from storage
through process, moving the form of worked material from department to department,
from machine to machine ,the material flows in and out of temporary storage is fed
through assembly lines for final assembly. Provision is made for inspection, packaging
and storing the material as finished product.
Advantages of good plant layout to the workers :
• Reduces the effort of the workers.
• Reduces the number of handling.
• Permits working at maximumefficiency.
• Reduces the number of accidents.
• Provides basis for higher earnings.
Advantages of a good plant layout in labour cost:
• Increases output per man hour.
• Reduces number of operators.
• Loss setup time involved
Advantages of a good plant lay out in production control:
• Reduces production control expenses
• Pace production
\
P a g e | 103
Fundamental concepts of plant layout:
In apprising the advantages of good layout in the light of conditions
prevailing in a particular plant, it is well to bear in mind the following concepts of
plant layout.
• Majorpartofproductionworksisnotprocessing,asisinitiallysupposebut material
handling.
• Then speed of production in the plant is determined primarily by the
adequacies of its material handling facilities.
• A good plant layout is designed to provide the proper facility for material
handling.
• The factory is altered or constructed around the prescribed plant layout.
• Theproductionefficiencyoftheplantisdeterminedbythelimitationsofits layout.
TYPES OF DEPARTMENT
• Processing department.
• This department performs machining assembly and packaging.
• Service department.
• These constitute the facilities provided to keep the processing department in
operation without interruption.
• Administrative department.
• This department administrative sales, engineering, accounting production
control, departments etc.
PLANNING THE PROCESSING
• Theplantlayoutengineershouldobtaindataonbuildingelevation,column spacing,
door and conveyors.
• The conveyors should be placed at reasonable height to malfunctioning and
waste.
• The traffic in the plant may be greatly by location store rooms close to the
building entrances.
P a g e | 104
• In addition to the above vehicular traffic should be separated from pedestrian
traffic and the roads should be wider.
PLANNING THE PLANT SERVICE FACILITIES:
•Materialreceivedataplantarrivesviatheparticularformsoftransportation which are
generally prescribed.
• Liquids such as chemicals are transported in tank cars, drums or pipelines
•Thereceivingdepartmentmustbewellequippedtoreceivethematerialinall modes.
• The design of a receiving involves the followingconsiderations:
1. Space, 2. Climate conditions, 3. Variety of vehicles
STOREROOM:
• A store roomis the reservoir for raw material.
• Worked materials, finished products, maintenance supplies etc are kept.
• The functional requirements of a store roomare:
1. protection tomaterials
2. handling of the materials
3. control points
The above factors also help the layout engineer to design the store room as per
requirements.
INSPECTION ROOM:
•The inspection room or quality control room should be located near the
production unit, so that the samples from the production plant Can be checked
for its quality requirements.
• The labs should be well equipped and should be properly planned.
WATER STORAGE:
• Water is used in the plant for variety of purposes.
• A plant must have adequate water supply to crater all these needs.
P a g e | 105
•By far the most reliable and effectives means of fire protection is the automatic
sprinkler system.
•The sprinkler system is fitted with a sensitive transducer which lets water up to a
height of 15 feet.
• So the water storage system should be planned out with most care.
POWER AND LIGHTINGSYSTEM:
• Power and lighting systems forms the main part of the plant.
• The significant features of the power plant operations are,
1. For supplying steam.
2. Providing heat for process operations.
3. supplying power to run motor.
4. providing light to plant.
5. power for surplus use.
PLANNING OF ADMINISTRATIVE BLOCK:
•Location of an administrative block depends upon the geographic location with
respect to the plant functions.
•The general administrative block should have administrative rooms, conference
room and vault room storage of documents and records.
•The employee service facility consists of parking lots, Employment office
cafeteria, first aid stations and medical department etc. ref[6]
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Plant layout
P a g e | 107
10. Economic Analysis An acceptable plant design must present a process that is capable of operating
under conditions which will yield a profit.
It is essential that chemical engineer be aware of the many different types of
cost involved in manufacturing processes. Capital must be allocated for direct plant
expenses; such as those for raw materials, labor, and equipment. Besides direct
expenses, many other indirect expenses are incurred, and these must be included if a
complete analysis of the total cost is to be obtained. Some examples of these indirect
expenses are administrative salaries, product distribution costs and cost for interplant
communication.
10.1 Estimation of Equipment Cost
Total income-All expenses= Net profit
Equipment Cost (Rs.)
Exchanger E-101 154427
Exchanger E-102 183702
Condenser E-103 175501
Reactor R-102 193459
Re-boiler E-104 938765
Reactor R-101 5400000
Distillation Column T-102 2982000
Flash vessel V-101 120000
Absorber T-101 4431117
P a g e | 108
10.2 Estimation of Total Capital Investment
Direct Cost (Rs)
Purchased equipment cost = Rs. 14578971
Purchased equipment installation = 0.47× 14578971 = Rs. 6852116.37
Instrumentation & Process Control = 0.12 × 14578971 = Rs. 1749476.52
Piping (installed) = 0.66 × 14578971 = Rs. 9622120.86
Building (Including Services) = 0.18×14578971 = Rs. 2624214.78
Yard improvements = 0.1 × 14578971 = Rs. 1457897.1
Service facilities (installed) = 0.7 × 14578971 = Rs. 10205279.7
Land = 0.06 × 14578971 = Rs. 874738.26
Total direct plant cost = Rs. 47964904.6
Indirect Cost
Engg & Supervision = 0.33 × 14578971 = Rs. 4811060.43
Construction expenses = 0.41 × 14578971 = Rs. 5977378.1
Total Indirect Cost = Rs. 10788438.54
Total Direct & Indirect Cost = Rs. 58753343.14
Contractor’s fee = 0.05 × 58753343.14 = Rs. 2937667.157
Contingency = 0.1 × 58753343.14 = Rs. 5875334.3
Fixed Capital Investment = Total (direct +indirect) cost +contingency
+Contractor’sfee
= Rs. 67566344.6
Total Capital Investment = F.C.I + W.C.
Now
W.C = 0.15 (T.C.I)
P a g e | 109
= 0.15 (67566344.6 + W.C)
W.C = Rs. 11923472.58
T.C.I = 11923472.58+67566344.6
= Rs. 79489817.18
= 80 million rupees
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11. Safety and Health Hazards & pollution Control11.1 Effects of Human Exposure
In many occupational situations workers are exposed to mixtures of acid
anhydrides, including maleic anhydride, phthalic anhydride, and trimellitic anhydride.
For example, Barker et al. (1998) studied a cohort of 506 workers exposed to these
anhydrides. In one factory, workers were exposed only to trimellitic anhydride, which
has the lowest acceptable occupational exposure limit (40 mg/m3) of the three
anhydrides. In that factory there was an increased prevalence of sensitization to acid
anhydride and work related respiratory symptoms with increasing full shift exposure
even extending down to levels below the current occupational standard. However,
none of the workplaces had exposure only to maleic anhydride and a doseresponse
relationship was not seen with mixed exposures. The following reports involve
exposure only to maleic anhydride.
There are several case reports describing asthmatic responses possibly resulting
from exposure to maleic anhydride. An individual showed an acute asthmatic reaction
after exposure to dust containing maleic anhydride (Lee et al., 1991). Workplace
concentrations of maleic anhydride were 0.83 mg/m3 in the inspirable particulate mass
and 0.17 mg/m3 in the respirable particulate mass. Bronchial provocation testing was
performed with phthalic anhydride, lactose, and maleic anhydride. Exposure of this
individual to maleic anhydride (by bronchial provocation testing) at 0.83 mg/m3 and
0.09 mg/m3 in inspirable and respirable particulate mass, respectively, showed a
response of cough, rhinitis, and tearing within two minutes. Within 30 minutes, rales
developed in both lungs and peak flow rate decreased 55%. An individual
occupationally exposed to maleic anhydride developed wheezing and dyspnea upon
exposure (Gannon et al., 1992). After a period without exposure, two re-exposures
both resulted in episodes of severe hemolytic anemia. There was no evidence of
pulmonary hemorrhage.Radioallergosorbent testing showed specific IgE antibodies
against human serum albumin conjugates with maleic anhydride, phthalic anhydride,
and trimellitic anhydride, but not with tetrachlorphthalic anhydride. A critique of the
Gannon et al. (1992) study by Jackson and Jones (1993) questions the relationship of
P a g e | 111
maleic anhydride exposure to the onset of the anemia, since there were extended
periods of exposure to maleic anhydride before symptoms appeared. Another case
report described occupational asthma due to exposure to maleic anhydride ..
Humans exposed to maleic anhydride showed respiratory tract and eye
irritation at concentrations of 0.25 to 0.38 ppm (1 to 1.6 mg/m3) maleic anhydride
(Grigor’eva, 1964). No irritation was reported at 0.22 ppm maleic anhydride.
11.2 Effects of Animal Exposure
Short et al. (1988) chronically exposed CD rats (15/sex/group), Engle hamsters
(15/sex/group), and rhesus monkeys (3/sex/group) to maleic anhydride by inhalation.
Four groups of each species were exposed to concentrations of 0, 1.1, 3.3, or 9.8
mg/m3 maleic anhydride for 6 (Determination of Non-cancer Chronic Reference
Exposure Levels Batch 2B December 2001 A – 67) Maleic anhydride hours/day, 5
days/week, for 6 months in stainless steel and glass inhalation chambers. Solid maleic
anhydride was heated to 53°C to generate vapors, which were then mixed with a
stream of nitrogen. Chamber target levels were monitored by gas chromatography as
total maleic (maleic anhydride plus maleic acid). No exposure-related increase in
mortality occurred. Of the species examined, only rats showed significant changes in
body weight during the course of the experiment, with reductions among males in the
high-dose groups after exposure day 40 and a transient weight reduction from days 78-
127 in the mid-dose group. All species exposed to any level of maleic anhydride
showed signs of irritation of the nose and eyes, with nasal discharge, dyspnea, and
sneezing reported frequently. No exposure-related eye abnormalities were reported.
The severity of symptoms was reported to increase with increased dose. No dose
related effects were observed in hematological parameters, clinical chemistry, or
urinalysis. No effects on pulmonary function in monkeys were observed. Dose-related
increases in the incidence of hyperplasic change in the nasal epithelium occurred in
rats in all exposed groups, and in hamsters in the mid- and high-dose groups.
Neutrophilic infiltration of the epithelium of the nasal tissue was observed in all
species examined at all exposure levels. All changes in the nasal tissues were judged
P a g e | 112
to be reversible. The only other significant histopathological observation was slight
hemosiderin pigmentation in the spleens of female rats in the high-dose group.
The teratogenicity and multigeneration reproductive toxicity of maleic
anhydride were also investigated (Short et al., 1986). To evaluate teratogenicity,
pregnant CD rats were treated orally with maleic anhydride in corn oil at
concentrations of 0, 30, 90, or 140 mg/kg-day from gestational days 6-15. Animals
were necropsied on gestational day 20. No statistically significant dose-related effects
were observed in maternal weight gain, implantation, fetal viability, post-implantation
loss, fetal weight, or malformations. Groups of 10 male rats and 20 female rats/group
(F0 animals) were orally treated with 0, 20, 55, or 150 mg/kg-day maleic anhydride in
corn oil to study multigeneration reproductive toxicity. Animals within the same dose
group were bred together after 80 days of treatment to produce two F1 generation
animals (F1a and F1b) and animals from the F1 generation were interbred to produce
two F2 generation animals (F2a and F2b). A significant increase in mortality was
observed among both F0 and F1 (Determination of Noncancer Chronic Reference
Exposure Levels Batch 2B December 2001A – 68) Maleic anhydride generation
animals in the high-dose group. Total body weight was significantly reduced in
animals in the high-dose group at Week 11 of exposure for the F0 generation males
and females and at Week 30 of exposure in the F1 generation males. No consistent
P a g e | 113
pattern of dose- or treatment-related effect on fertility, litter size, or pup survival was
observed. Examination of F0 animals showed necrosis of the renal cortex in the high-
dose group (60% of males and 15% of females). Absolute kidney weights were
significantly increased in F1 females in the low- and mid-dose groups, although there
was no histological correlate. No changes in organ weight or histology were observed
in the F2 generation animals.
11.3 Potential for Differential Impacts on Children's Health
Minimal teratogenic and reproductive adverse effects were seen at the lowest
oral dose of maleic anhydride (20 mg/kg-day), given to rats during gestation (Short et
al., 1986). This dose is equivalent to a person inhaling 70 mg/m3. Thus the chronic
REL of 0.7 μg/m3 should protect children. Maleic anhydride is a respiratory irritant
and an inducer of asthma. Exacerbation of asthma has a more severe impact on
children than on adults. However, there is no direct evidence in the literature to
quantify a differential effect of maleic anhydride in children.
Toxicology (This section is for information only and should not be taken as the basis
for OSHA policy).
Maleic anhydride is a severe irritant to the eyes, skin and respiratory tract
which can, upon exposure, produce intense burning sensations in the eyes and throat
with coughing and vomiting. Among workers repeatedly exposed to 5-10 mg/m3,
toxic effects included ulceration of nasal mucous membranes, chronic bronchitis, and
in some cases, asthma. Other potential effects of exposure are dermatitis, pulmonary
edema, respiratory sensitization, skin sensitization, photophobia and double vision.
(Ref. 5.2.)
11.4 Reliable quantitation limit
The reliable quantitation limit is 97 ng of maleic anhydride per sample or
0.005 mg/m3 based on the recommended air volume. This is the smallest amount of
maleic anhydride which can be quantitated within the requirements of 75% recovery
and 95% confidence limits of less than ±25%. (Section 4.2.)
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11.5 First -Aid Measures
Ingestion
Do not induce vomiting. Have a conscious person drink several glasses of
water or milk. Seek immediate medical attention.
Inhalation:
Allow the victim to rest in a well ventilated area. Seek immediate medical
attention.
Skin Contact
After contact with skin, wash immediately with plenty of water. If irritation
persists seek medical attention. Wash contaminated clothing before reusing.
Eyes
Immediately flush with water for at least 15 minutes, keeping eyelids open. Seek
medical attention
FIRE FIGHTING MEASURES
Small fire: Carbon dioxide, water, foam.
Large fire: Water spray, fog or foam, do not use water jet.
Extinguishing Media:
11.7 Do Not Use Dry Chemical
Large volumes of gases could be produced by reaction with Maleic
Anhydride. Special Fire-Fighting Procedures: Wear self-contained breathing apparatus
with full face piece operated in the positive pressure demand mode and full body
protection when fighting fires. Hazardous Combustion Products: Carbon Dioxide,
Carbon Monoxide. Unusual Fire and Explosion Hazards: Unstable, or air-reactive or
water-reactive chemical involved Vapors from melted material can be ignited. Keep
melted material away from ignition sources. May form flammable dust-air mixtures
P a g e | 115
when finely divided. Prevent dust buildup by providing adequate ventilation during
grinding or milling Operations
11.8 Handling and Storage
Handling
Eye wash and safety shower should be available nearby when this product
is handled or used. Minimum feasible handling temperatures should be maintained.
Avoid generating mist or dust. Exercise care when opening bleeders and sampling
ports. Do not breathe gas, fumes, vapor or spray. Do not ingest. Avoid contact with
skin and eyes. After handling, always wash hands thoroughly with soap and water.
Storage Store away from incompatible materials.Store at temperatures not
exceeding 70°C (158°F). Contains moisture sensitive material -- store in a dry
place.
11.9 Exposure Controls/Personal Protection
Eye/Face Protection :
Avoid eye contact. Chemical type goggles with face shield must be worn.
Do not wear contact lenses.
Skin Protection
Protective clothing such as coveralls or lab coats must be worn. Gloves
resistant to chemicals and petroleum distillates required. When handling large
quantities, impervious suits, gloves, and rubber boots must be worn. Remove and dry-
clean or launder clothing soaked or spoiled with this material before reuse. Dry
cleaning of contaminated clothing may be more effective than normal laundering.
Inform individuals responsible for cleaning of potential hazards associated with
handling contaminated clothing. Respiratory Protection Airborne concentrations
should be kept to the lowest levels possible. If vapor, mist or dust is generated and the
P a g e | 116
occupational exposure limit of the product is exceeded, use appropriate NIOSH or
MSHA approved air purifying or air supplied respirator after determining the airborne
concentration of the contaminant. Air supplied respirators should always be worn
when airborne concentration of the contaminant or oxygen content is unknown.
11.10 Toxicological Information
Oral LD-50 (rat) 1030 mg/kg Dermal LD-50 (rabbit) 2620 mg/kg
Skin irritation (rabbit), corrosive Eye irritation (rabbit) extremely irritating
Sensitization. The limited number of animal studies investigating the dermal or
respiratory sensitization potential of maleic anhydride have not shown conclusive
evidence of sensitization potential. Although there have been reports of human dermal
or respiratory sensitization from maleic anhydride exposures, the number of reports
has been low when compared to the number of potentially exposed individuals. Maleic
anhydride has a low potential for human dermal or respiratory sensitization.
Effects of Acute Exposure Extremely dangerous in case of skin contact
(corrosive, irritant), of eye contact (irritant) and inhalation. Very dangerous in case of
ingestion. Slightly dangerous in case of skin contact (sensitizer). Eye contact can
result in corneal damage or blindness. Inhalation of dust will produce irritation to
gastro-intestinal or respiratory tract, characterized by burning, sneezing and coughing.
Effects of Chronic Exposure:
Carcinogenic effects Not available.
Mutagenic effects: Not available.
Teratogenic Effects: Not available.
Toxicity of the product to the Reproductive system: Not available.
Repeated exposure of the eyes to low level dust can produce
irritation. Repeated skin exposure can cause local skin destruction or dermatitis.
Repeated inhalation can cause a varying degree of respiratory irritation or lung
damage. Repeated exposure to a highly toxic material may produce general
deterioration of health by accumulation in one or many human organs.
P a g e | 117
11.11 Ecological Information
Aquatic Toxicity LC50 - 96hr 230 mg/liter (mosquito fish) practically
nontoxic. LC50 - 24hr 150 mg/liter (blue gill sunfish) practically nontoxic. Mobility
This product is not likely to volatilize rapidly into the air because of its low vapor
pressure. Bioaccumulative potential of this product is not expected to bioaccumulate
through food chains in the environment. Remarks this product will hydrolyze rapidly
to the acid. Expected to be slightly toxic to aquatic species because of acidity.
11.12 Disposal Considerations
Waste Disposal Methods Recycle if possible. Consult your local
authorities. This product has the RCRA characteristics of corrosivity, and is identified
under RCRA as Maleic Anhydride. If discarded in its present form, it would have the
hazardous waste numbers D002 and U147. Under RCRA, it is the responsibility of the
user of the product to determine, at the time of disposal, whether the product meets
RCRA criteria for hazardous waste. Remarks Do not allow to enter drains or sewers.
Do not allow to drain into surface waters.
P a g e | 118
12. References:
1. Zhou J, Wang LI, Wang CH, Chen T, Yu H, Yang Q (2005) Synthesis and self assembly of amphiphilic maleic anhydride–stearyl methacrylate copolymer.J Polymer 46:1157–11642. Nieuwhof R, Marcelis A, Sudholter E (1999) Side-chain liquid-crystalline polymers from the alternating copolymerization of maleic anhydride and 1-olefins carrying biphenyl mesogens. J Macromol . 32:1398–14063. Al-Sabagh A, Noor MR, Din EL, Morsi RE, Elsabee MZ (2009) Styrene-maleic anhydride copolymers esters as flow improvers of waxy crude oil. J Pet Sci Eng 62:139–1464. Zhu LP, Yi Z, Liu F, Wei XZ, Zhu BK, Xu YY (2008) Amphiphilic graft copolymers based on ultrahigh molecular weight poly(styrene-alt-maleic anhydride) with poly(ethylene glycol) side chain for surface modification of polyethersulfone membranes. Eur Polym J 44:1907–19145. Nieuwhof R, Koudijs A, Marcelis A, Sudholter E (1999) Modification of sidechainliquid-crystalline poly(maleic anhydride-co-alt-1-alkene
6. Merck Index, 11th Edition, 5586.
7. Kurt Lohbeck; Herbert Haferkorn; Werner Fuhrmann; Norbert Fedtke (2005), "Maleic and Fumaric Acids", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a16_053
8. Samuel Danishefsky, Takeshi Kitahara, and Paul F. Schuda (1983). "Preparation and Diels-Alder Reaction of a Highly Nucleophilic Diene: trans-1-Methoxyl-3-Trimethylsiloxy-1,3-Butadiene and 5β-Methoxycyclohexan-1-one-3β,4β-Dicarboxylic acid Andhydride". Org. Synth. 61: 147.
9. Horie, T.; Sumino, M.; Tanaka, T.; Matsushita, Y.; Ichimura, T.; Yoshida, J. I. (2010). "Photodimerization of Maleic Anhydride in a Microreactor Without Clogging". Organic Process Research & Development 14 (2): 100128104701019
10. "Substance Evaluation Report: Maleic anhydride". Environment Agency Austria.
11. "Tainted starch found in Tainan yet again". Want China Times. 2013-12-19.12. Felder, R. M. and R. W. Rousseau, Elementary Principles of Chemical Processes (3rd ed.), Wiley, New York, 2000.13. Wankat, P., Equilibrium Staged Separation Processes, Prentice Hall, Upper Saddle
River, NJ, 1988.14. The Properties of Gases and Liquids, Fifth Edition Bruce E. Poling, JohnM. Prausnitz, John P. O’Connell15.Chemical process design by Coulson__Richardsons-vol-6, 4th edtn , pg 34-90616. Plant Design &Economics for Chemical Engineers-Peters Timmerhaus, fourth edition,ch-6(pg 226-350)
17.Chemical process Design by M.V.Joshi,4thedition,pg-220 to300