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PRO/II CASEBOOK

Methyl Tertiary ButylEther (M TBE) Plant

Abstract

This casebook demonstrates the use of PRO/II ® in the simulation of the synthesisof methyl tert -butyl ether (MTBE). MTBE is of current interest as an octane enhancerfor reformulated gasolines, and is becoming increasingly important as stricter airpollution control measures are implemented. A PRO/II simulation model of an MTBEplant is presented here. The process plant includes a reactor and an azeotropicdistillation column for separation of the MTBE product. A reactive distillation sectionis added to the MTBE azeotropic column in order to increase the overall conversionto MTBE. This is followed by the methanol recovery section which includes a

liquid-liquid extractor. SimSci’s

SM

SRKM bank provides a good simulation of theVLE fractionators and the VLLE extractor. All product specifications are achieved.The thermodynamics successfully predicts the azeotropic removal of methanol fromthe MTBE product stream.

Feature Highli ghts Petrochemicals Application

Stoichiometric Reactor Units

Multi-tray Reactive Distillation Column

Complex Reaction Kinetic Models

Liquid-liquid Extraction Column Using VLLE Thermodynamics

Column Condenser Modeled as an Attached, Rigorous Heat Exchanger

Column Tray Rating

Recycle Acceleration Techniques

Casebook #4, Rev 1. Methyl Tertiary Butyl Ether (MTBE) Plant, March 1995

PRO/II is a registered mark of SIMULATION SCIENCES INC.

SIMSCI is a service mark of SIMULATION SCIENCES INC.

Amberlyst is a trademark of Rohm & Haas

© Copyright 1995, SIMULATION SCIENCES INC. ALL RIGHTS RESERVED


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Customer Service and Support

Customer Services Address and Phone NumbersThe telephone numbers of Customer Support are given below:

Support Center Telephone Facsimi le

USA and CanadaSimulation Sciences Inc.601 S. Valencia AveBrea, California 92621

(800) SIMSCI1 (714) 579-0354(714) 579-0412

Pacifi c RimSimulation Sciences Inc.601 S Valencia AveBrea, California 92621

(800) 827-7999 (714) 579-7468(714) 579-0412

JapanSIMSCI Japan K.K.Towa Hamamatsucho Building #203

2-6-2 HamamatsuchoMinato-ku, Tokyo 105, Japan

81-3-3432-4631 81-3-3432-4633

Europe/IndiaSIMSCI InternationalHigh Bank House, Exchange StreetStockport, CheshireUnited Kingdom SK3 OET

44-161-429-6744 44-161-480-9063

South Ameri caSIMSCI Latinoamerica C.A.Centro Banaven (Cubo Negro)Torre ‘‘A’’, PH A-2

Av. La Estancia, ChuaoCaracas, 1060, Venezuela

58-2-959-8033 58-2-993-2717


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Introduction

What i s MTBE?Methyl tertiary butyl ether (MTBE) is an octane enhancing agent for unleaded motor gasoline.

Suitable feedstocks for the manufacture of MTBE are mixed butylenes from liquid feed ethylenecrackers and from fluid catalytic crackers. In some plants, raffinates from butadiene extraction

or catalytic butane dehydrogenation are used as feed. MTBE synthesis also offers a method ofselectively removing isobutylene from mixed C4 streams. This enables the recovery of high purity1-butene and 2-butene which are superior sulfuric acid alkylation feedstocks.

Why is M TBE an Impor tant Comm odity?MTBE has a number of desirable properties that makes it a suitable gasoline additive:

Table 1: Desirable Properties of M TBE

Property Advantage

RVP of 8-10 psiLow boiling point

Low vapor pressure results in reducedemissions

RON+MON/2 octane number of ~109 More complete combustion withoutreducing engine power

Increases front-end octane number (FON)of gasoline

Reduces knocking during acceleration

Also, the addition of MTBE to gasolines generally implies a reduced aromatic and butane content.

The current and future demand for MTBE and other oxygenates for reformulated gasoline stemsfrom environmental legislation and restrictions on air pollutant levels. Most US refiners haveelected to use MTBE (and other esters) rather than ethanol (and other alcohols) as their mainoxygenate for reformulated gasoline. Future US demand for MTBE is expected to grow at a rateof over 10% per year for the next 5 years. Recent environmental legislation in the Far East(especially Japan and Korea) has resulted in an increased demand for MTBE in those markets.In Europe, lead-based gasolines are being phased out, resulting in increasing use of MTBE andother octane-enhancing agents.

Alternati ve Routes to M TBE SynthesisThere are two principal processes for MTBE synthesis currently in use. Both produce MTBE byreacting isobutylenes with methanol using sulfonic ion-exchange resins as the catalyst. TheMTBE product is separated in an azeotropic distillation column, and the unreacted methanol isrecovered and recycled to the MTBE reactor.

Standard (Hüls) Process

The key feature of this process is the fixed bed MTBE reactor used prior to the azeotropicdistillation column. Conversions of isobutylene to MTBE are in the range 85-95%. In many plants,two reactors are used in tandem, along with recycle, in order to increase the overall conversioncloser to 99%.

Etherm ax Process 1

The Ethermax process, developed jointly by UOP Corporation, Koch Engineering, and Hüls AGutilizes a single fixed-bed reactor followed by a reactive distillation column. In this process, towerpacking that holds the resin catalyst is placed in a section of the MTBE azeotropic distillationtower. The MTBE reaction is completed in the column and the product is separated at the sametime. The overall conversion of isobutylene to MTBE can be improved to 99% or greater withthis process, with almost no increase in capital expenditure.

1 Chemical Engineering Progress, p. 15, Aug. 1991.

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Catalyst

A common catalyst for the MTBE synthesis process is the Amberlyst 15 polymeric catalystdeveloped by Rohm and Haas. Approximate properties of the commercial form of this catalyst,along with suggested operating conditions are provided below. For exact catalyst properties,please contact the manufacturer.

Table 2: Approximate Properties of Amberlyst 15 Catalyst

Properties

Physical Form Spherical beads

Ionic Form Hydrogen

Acid Site Concentration 1.8 meq/ml (4.9 meq/g)

Moisture Content 53 %

Apparent Density 770 g/l

Particle Size 0.35-1.2 mm

Shrinkage: Wet to methanol Wet to MTBE

4%12%

Porosity 0.30 cc/gAverage Pore Diameter 250 A

Surface Area 45 m2/g

Bulk Density 48 lb/ft3

Operating Conditions

Maximum Temperature 120 C

Minimum Bed Depth 0.61 m

Flowrate, LHSV 1-5 hr-1

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Process Descripti on

Reactor SectionMTBE is manufactured by catalytically reacting isobutylene and methanol in a fixed-bed reactorat a moderate temperature and pressure. The reaction is exothermic and reversible, and iscarried out in the liquid phase over a fixed bed of ion-exchange resin-type catalyst. It is highly

selective since methanol reacts preferentially with the tertiary olefin.In this MTBE process, an isobutylene-rich mixed C4 stream is mixed with fresh methanol and asmall amount of recycle methanol and fed to the reactor section. The reactors are cooled toprolong catalyst life and to minimize the undesirable side reactions such as dimerization ofisobutylene. Temperatures below 94 C (200 F) are recommended.

The methanol-to-isobutylene ratio in the reactor feed is kept low to minimize the costs ofrecovering unreacted methanol, and to facilitate the operation of the MTBE column (discussedlater). Generally, this ratio is maintained close to the stoichiometic (molar) value of unity. Table3 contains the reactor feed composition used in this model.

Table 3: Reactor Feed

Stream Stream No Flowrate (kgmole/hr)C4 Feed 2 850

Temperature 16 C

Pressure 1620 kPa

Component Library Name Mol e Percent

N-butane NC4 9.0

Isobutane IC4 41.0

1-butene 1BUTENE 7.0

cis 2-butene BTC2 4.0

trans 2-butene BTT2 6.0

Isobutylene IBTE 33.0

MTBE MTBE 0.0tert-butanol TBA 0.0

Water H2O 0.19

Di-isobutylene (DIB) 244TM1P --------

Stream Stream No Flowrate (kgmole/hr)

Methanol Feed 1 277.5

Temperature 16 C

Pressure 1620 kPa

Component Library Name Mole Percent

Methanol MEOH 100.0

Stream Stream No Flowrate (kgmole/hr)Methanol Recycle 20 4.3

Temperature 44 C

Pressure 1724 kPa

Component Library Name Mole Percent

Methanol MEOH 93.02

Water H20 6.98

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An isobutylene conversion to MTBE of 90 to 93% is easily achieved in the reactor. Overallisobutylene conversions higher than those obtained in the standard process can be achieved byeither recycling a portion of the MTBE column overhead product, or by providing a second reactorunit and MTBE column downstream of the first MTBE column. The cost-effectiveness of theseoptions vary from plant to plant, but both require greater capital expenditure. In the reactivedistillation process, no major increase in capital expenditure is required and overall isobutyleneconversions of over 99% are easily obtained.

Any water in the reactor feed (from recycle methanol) is instantly converted to t-butanol (TBA).Another impurity, di-isobutylene (DIB), is formed by the dimerization of isobutylene. While theformation of di-isobutylene and t-butanol should be minimized, their presence in small concen-trations in the MTBE product is acceptable since these byproducts also have very high octanenumbers.

Table 4 shows the three main reactions used in the stoichiometric reactor model. The basecomponent and the fraction converted are also shown.

Table 4: Reaction Stoichiom etry

Reaction Base Component Conversion %

2 (IBTE) =DIB IBTE 0.25

H2O +IBTE =TBA H2O 100.0

IBTE +MEOH =MTBE MEOH 93.0

MTBE Recovery SectionIn the Hüls process, the reactor products are processed in the MTBE column where MTBE, alongwith t-butanol (TBA), dimerized butylene (DIB) and a trace amount of methanol, are removed asthe bottoms product. In the Ethermax process, further reaction of the isobutylene to MTBE takesplace in a section of the distillation column containing the catalyst resin in tower packing. TheMTBE is removed as the bottoms product in a manner similar to the standard process. The MTBEproduct is greater than 99.5% pure and requires no further purification.

The key to operating the MTBE column is to have sufficient amounts of C4s in the column feedto form azeotropes with the methanol in the feed. Conversely, if a proportionately large amount

of methanol is present in the column feed, it may result in breakthrough of methanol with theMTBE bottoms product. Therefore, suitable azeotrope formation is possible only when a limitedexcess of methanol is used in the reactor feed. In this manner, unreacted methanol, which hasa higher boiling point than MTBE, is fractionated away from the MTBE bottoms. The overheadproduct containing non-reactive linear butenes, iso and normal butanes, and unreacted methanoland isobutylene, is sent to the methanol recovery section.

Methanol Recovery SectionIn the methanol recovery section, the MTBE column overhead product is water washed to extractmethanol. This unit is simulated as a liquid-liquid extraction column. The raffinate, which containsless than 10 ppm methanol, is suitable for recovering high purity C4 isomers, or as a feed to analkylation unit.

The extract phase which contains water, methanol and small amounts of dissolved hydrocarbonsis warmed and flashed to remove the hydrocarbons. The resultant methanol-water mixture isfractionated to recover methanol as the overhead product. The methanol (with a trace of water)is recycled to the MTBE reactor. The wash water stream from the bottoms, along with a smallamount of makeup water, is returned to the water wash column.

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Process Simulation

The full input for the process simulated here may be found in Appendix A. Fragments of the inputare shown here to illustrate points of interest.

Symbols UsedThe symbol

n

is used beside the highlighted fragments of the keyword input file. The number ‘‘n’’ refers to thechapter in the PRO/II Keyword Input Manual where detailed explanations of the input data maybe found. The PRO/II Keyword Input Manual may be obtained from SimSci.

General DataSI units are used. The total calculation sequence is specified. The calculator CAL0 is processedbefore the MTBE column in order to set the reaction factor equal to 1.0 on the first pass throughthe flowsheet. The MBAL keyword on the PRINT statement specifies that an overall massbalance be reported in the final output.

5KeywordSyntax

DIMENSION SI, TEMP=C PRINT INPUT = ALL, STREAM = COMPONENT, MBAL

SEQUENCE HX-1 , RX-1, HX-2A, CAL0 , T-1 , CONVERSION , &

HX-2B , P-1 , HX-3 , &

T-2 , HX4A , V-1 , D-1 , P-2 , T-3 , &

CAL1 , P-4 , HX4B , HX-5 , P-3 , RC-1

Component DataAll the components in the simulation are in the PRO/II databank.

Thermodynami c DataThe VLE fractionators are simulated well with SimSci’s modified Soave-Redlich-Kwong (SRKM)equation of state method. For this method, PRO/II contains extensive, built-in databanks thatencompass binary interaction parameter data for the majority of component pairs present in thissimulation. In this casebook, however, binary interaction data (kijs) are directly supplied for 8component pairs to improve the accuracy of the separations in the columns and to demonstratethe input syntax.

Transport property calculations are selected by specifying the TRANSPORT keyword in orderto use the rigorous heat exchanger model in the MeOH recovery section. The liquid extractionunit is simulated using the SRKM method for VLLE thermodynamics with binary interaction dataagain supplied as part of the input. Note that the L1KEY component (i.e., the predominantcomponent in the L1 liquid phase) is specified as component 1, n-butane. The L2KEY componentis specified to be component 10, water. Explicitly specifying the key components eliminates theneed for PRO/II to find an appropriate immiscible pair, and reduces computation time. Note alsothat each thermodynamic set is given a unique set id number. All the azeotropes are properlypredicted.

23.3KeywordSyntax

METHOD SYSTEM=SRKM, TRANSPORT=PURE, SET=S1

KVAL

SRKM 1, 9, 0.046973, 0.126027,0,0,0,0,1,1

SRKM 3, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 4, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 5, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 6, 8, 0.135525,-0.032271,0,0,0,0,1,1

SRKM 8, 9,-0.073971,-0.055222,0,0,0,0,1,1

SRKM 9,10,-0.145000,-0.253000,0,0,0,0,1,1

SRKM 7,11, 0.05785, -0.0093,-10.144,6.17,0,0,1,1

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METHOD SYSTEM(VLLE)=SRKM, L1KEY=1, L2KEY=10, SET=S2

KVAL

SRKM 1, 9, 0.046973, 0.126027,0,0,0,0,1,1

SRKM 3, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 4, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 5, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 6, 8, 0.135525,-0.032271,0,0,0,0,1,1

SRKM 8, 9,-0.073971,-0.055222,0,0,0,0,1,1

SRKM 9,10,-0.145000,-0.253000,0,0,0,0,1,1 SRKM 7,11, 0.05785, -0.0093,-10.144,6.17,0,0,1,1

Stream Data

Feed Streams

The mixed C4 feed stream, and the methanol feed stream are specified in the normal manner,using the compositions and stream conditions given in Table 3.

Recycle Stream

The composition of the recycle methanol-water stream from the MeOH recovery section isestimated initially for the first run through the flowsheet (see Table 3).

31

KeywordSyntax

$ RECYCLE STREAM ---- INITIAL GUESS

PROP STRM=20, TEMP=44, PRES=1724, COMP=8,4.0/10,0.3

Other Streams

The amount of wash water in stream 10 (the feed to column T-2) is provided. The temperatureand pressure of the cooling water stream (CW) for the condenser for column T-3 is provided,along with an estimate of the flowrate. An estimated value is given for the flowrate of the make-upwater stream, MKUP.

31KeywordSyntax

PROP STRM=10, TEMP=38, PRES=793, COMP=10,375

PROP STRM=CW, TEMP=21, PRES=690, COMP=10,100, RATE(V)=75

PROP STRM=MKUP, TEMP=38, PRES=350, COMP=10,500

Unit Operations

MTBE ReactionThe MTBE reaction section of the plant is shown in Figure 2 below.

Figur e 2: MTBE Reaction Section

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With reference to the previous figure, mixed C4s (stream 2) are combined with fresh methanol(stream 1) and recycle methanol (stream 20) and pre-heated in a heat exchanger (HX-1) to 43.5C. The heated feed (stream 3) is then sent to a conversion reactor (RX-1) which is maintainedat 55 C by circulating a coolant. The three reactions defined in Table 4 take place in this reactorat the specified conversion levels. A pressure drop of 69 KPa through the reactor is also specified.

The stoichiometries of the major and minor reactions in the MTBE process are provided In theRXDATA Category of input:

48KeywordSyntax

$ Reaction Data for Reactors

$

RXSET ID=ST1

REACTION ID=1

STOIC 6,-2 / 11,1 $ IBTE + IBTE = DIB

REACTION ID=2

STOIC 10,-1 / 6,-1 / 9,1 $ H2O + IBTE = TBA

REACTION ID=3

STOIC 6,-1 / 8,-1 / 7,1 $ IBTE + MEOH = MTBE

The unit is modeled as a conversion reactor in the Unit Operations Category of input:

92

KeywordSyntax

CONREACTOR UID=RX-1, NAME=REACTORS

FEED 3 PROD L=4

OPER TEMP=55, DP=69

RXCALC MODEL=STOIC

RXSTOIC RXSET=ST1

REACTION 1

BASE COMP=6

CONV 0.0025

REACTION 2

BASE COMP=10

CONV 1.00

REACTION 3

BASE COMP=8

CONV 0.93

MTBE Distillation and RecoveryThe MTBE distillation and recovery section of the plant is shown in Figure 3 below.

Figure 3: MTBE Distillation and Recovery Section

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The reactor product (stream 4) exchanges heat with the MTBE column bottoms product inexchanger HX-2. Normally, this would create a thermal calculation loop. However, since thetemperature of stream 5 is known, this process is modeled by two separate heat exchangers,HX-2A and HX-2B as shown in Figure 3. Stream 4 from the reactors is heated to 72 C in HX-2Ato produce stream 5. The product of column T-1, stream 7, is cooled in exchanger HX2-B toproduce the MTBE product stream 8. The duty of exchanger HX-2A is defined to be equal to theduty in HX-2A. This approach avoids an unnecessary calculation loop since the temperature of

stream 5 is fixed at 72 C.

The heated stream 5 is fed to tray 15 of the 30 tray MTBE column (T-1). The MTBE column issimulated with the CHEMDIST algorithm using the SIMPLE initial estimate generator (IEG). Atop pressure of 621 KPa and a column pressure drop of 76.5 KPa are given. The condenser isoperated at a fixed temperature (TFIX) of 43.5 C and pressure of 621 KPa. The controlspecifications are a bottoms flowrate of 278 kgmoles/h and a reflux ratio of 1.1. The condenserand reboiler duties are varied to achieve these specifications.

The next step is to provide all the information required for specifying the reaction trays in thedistillation column.

How is Reactive Distill ation Impl emented in PRO/II?You can visualize the reaction zone of a distillation column as a series of boiling pot reactors.

On each reaction tray sits a bed of solid catalyst. Each tray is connected to the next in the forwarddirection (down the column) by the flow of liquid from one tray to the next, and in the reversedirection by the vapor flow moving up from one tray to the previous tray. See the PRO/II Reference Manual (obtainable from your SimSci representative) for detailed information on theReactive Distillation column algorithm.

For the reactive distillation process, the reaction zone (trays 8 through 13) is specified using theRXTRAY keyword. Note that the liquid volume of each of the reaction trays is also specifiedusing the LVOL keyword, and that the concentration of the dry catalyst (GCAT, in g/l) is specifiedusing a DEFINE statement. A value of 360 g/l is given for GCAT to represent commercial catalystloadings (corresponding to a wet catalyst density of 770 g/l at 53% moisture content ---- see Table2). The reaction factor, RXFACT, is used to demonstrate how the reaction rate in the simulationmodel can be varied to match data from an actual plant. For this casebook, RXFACT is set equalto 1.0, indicating that the reaction rate has not been adjusted.

75KeywordSyntax

COLUMN UID=T-1, NAME=MTBE COLUMN

PARA TRAY=30, CHEM=35

FEED 5, 15

PROD OVHD=6, BTMS=7,280

PSPEC TOP=621, DPCOL=76.5

COND TYPE=TFIX, PRES=621, TEMP=43.5

DUTY 1,1 / 2,30

VARY DUTY=1,2

SPEC STRM=7,RATE,VALUE=278.0

SPEC RRATIO, VALUE=1.1

PRINT PROP=ALL , COMP=M

PLOT LOG XCOMP=6,6/ 8, 8/ 7, 7/1,1

ESTI MODEL=SIMPLE

RXTRAY ALJX, 8 , 13

LVOL(M3) 8 , 5.0 / 13, 5.0

DEFINE GCAT AS 360.0

DEFINE RXFACT AS 1.0

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MTBE Kineti c ModelThe algorithm used for the reactive distillation column model is a Newtonian-based algorithm.Therefore, in order to accurately model the MTBE reaction in the distillation column, we need todetermine not only the reaction rate of the reaction, but also the temperature and compositionderivatives of the rate. These derivatives may be generated by one of two methods:

1. Numerically, by an estimation method

or

2. Analytically, by an expression based on the reaction rate equation.

The PRO/II program can automatically generate numerical estimates of the reaction ratederivatives. In many cases, this is sufficient. However, for certain types of reactions, the moreaccurate analytical derivatives provide better solutions. These are:

Reversible reactions

or

Exothermic reactions

or

Reactions where the equilibrium is sensitive to temperature

The MTBE reaction satisfies all three criteria. The reaction rate expression and its analyticalderivatives can be easily and readily entered by the user in the Procedure Data category of input.The MTBE reaction rate expression used in this simulation model is based on the rate expressiondescribed in a paper by Al-Jarallah et al 3. In this casebook, we will detail how to enter the reactionrate and the associated analytical derivatives for the MTBE reaction.

First, in the Reaction Data category of input, the stoichiometry of the forward reaction is given(IBTE + MEOH = MTBE) and the base component is defined to be MEOH. The kinetic data willbe provided later on in the Procedure Data category of input using FORTRAN-like language asthe procedure named ALJD.

75KeywordSyntax

RXSET ID=ALJX

REACTION ID=ALJ0

STOICH 6, -1/8, -1/7, 1

BASE COMP=8

KINETIC PROCEDURE=ALJD, POSITION=1

The reaction rate equation described by Al-Jarallah takes into account the forward and thereverse reaction. We have modified Al-Jarallah’s rate equation for this casebook to simulate theeffect of catalyst loading on the reaction rate. This was achieved by removing the catalyst termsfrom the concentration terms. The modified reaction rate is given by:

(1)

r s = k s K a

C AC B 0.5

− C C

1.5

K eq

(1 +K AC A +K B C b ))1.5

where:

ks = surface reaction rate constant = 1.2x1013exp(- 87900/RT) in (gmole/g catalyst)1.5 /hr (1a)KA = equilibrium adsorption constant = 5.1x10

-13exp(97500/RT) in g catalyst/gmole (1b)

KC = equilibrium adsorption constant = 1.6x10-16

exp(119000/RT) in g catalyst/gmole (1c)Keq = equilibrium constantCA = IBTE concentration in mole/lCB = MEOH concentration in mole/lCC = MTBE concentration in mole/l

3 Al-J arallah, A.M., M.A.B. Siddiqui, and A.K.K. Lee, 1988, Kinetics of Methyl Tertiary Butyl Ether Synthesis Catalyzed by Ion Exchange

Resin, Can. J . Chem. Eng., 66, 802-807.

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Kinetic Data

In the Procedure Data category of input, the PROCEDURE type of RXKINETIC is selected todenote that the procedure will be used in the Reactive Distillation column model. In addition,process data, and real and integer variables are defined:

47Keyword

Syntax

PROCEDURE DATA

PROCEDURE(RXKINE) ID=ALJD,NAME=Al-Jarallah PDATA GCAT , RXFACT

REAL KS , KA , KC , KALJ , KREH1 , KREH2 , KIZQ , KEQREF

INTEGER IBTE , MEOH , MTBE

Next, the indices for the components are set, a value is given for the gas constant in J/gm-moleK, and the basis for the temperature values in the procedure is set to an absolute basis. Inaddition, the temperature and composition rate derivatives are initially set equal to zero.

CODE

$

$ INITIALIZE DATA:

$ SET INDEXES FOR COMPONENTS

$ DEFINE GAS CONSTANT IN Joules/gm-mole K

$ Note: R could have been retrieved in input units by R=RGAS.

$ However, since the reaction basis won’t change, and $ RGAS will change with the default units, this

$ eliminates one possible source of error.

$ Initialize the local variable TK to the absolute temperature.

$ Note: The temperature basis for the flowsheet must be Centigrade

$ or Kelvin.

$ Set temperature and composition derivatives to zero.

$

IBTE = 6

MTBE = 7

MEOH = 8

R = 8.314

TK = RTABS

DO 1000 I1 = 1,NOR

DRDT(I1) = 0.0

DO 1000 I2 = 1,NOC 1000 DRDX(I2,I1) = 0.0

The surface reaction rate constant, ks, and the equilibrium adsorption constants, KA, and KB,are calculated using the expressions given previously as (1a), (1b), and (1c).

KS = 1.2E+13*EXP(-87900.0/(R*TK))

KA = 5.1E-13*EXP( 97500.0/(R*TK))

KC = 1.6E-16*EXP(119000.0/(R*TK))

Next, the derivatives of these constants are computed and are used later on in calculating therate derivatives.

$

DKSDT = KS * 87900.0 / R / (TK*TK)

DKADT = KA * (-1.0) * 97500.0 / R / (TK*TK)

DKCDT = KC * (-1.0) * 119000.0 / R / (TK*TK)

Then the bulk concentration of components A, B, and C per gram of catalyst (RHOA, RHOB,and RHOC) are determined from the liquid mole fractions of the components (XLIQ), the densityof the liquid, and the catalyst loading (GCAT) in g/l. Note that the liquid density, DENS, obtaineddirectly from PRO/II using the predefined variables, RLMRAT and RLVRAT, is in the user-speci-fied units of kg-moles/m

3 (SI units). Our basis for calculations is gm-moles/l and the conversion

factor between these kg-moles/m3 and gm-moles/l is 1.0. Also, note that the value of GCAT used

here is 12.4 g/l. This value is used because it is the catalyst loading at which data for theAl-Jarallah rate equation was collected.

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GCATX = 12.4

DENS=RLMRAT/RLVRAT

RHOA=(XLIQ(MEOH)*DENS/GCATX)

RHOB=(XLIQ(IBTE)*DENS/GCATX)

RHOC=(XLIQ(MTBE)*DENS/GCATX)

Expressions for the equilibrium constant and its derivative as functions of temperature areprovided based on equilibrium data published by Al-Jarallah et al .

KALJ = EXP(-17.31715+(7196.776/TK))

$

DKALJDT = - KALJ * 7196.776 / (TK*TK)

Then the reaction rate and rate derivatives with respect to temperature and composition aredetermined.

$

$ -------- Calculate reaction rate and derivatives by terms

$ -------- Units - RATE - gram-mole / gram catalyst / hr.

$

$ Denominator & derivatives.

$

RDEN = 1.0 + ( KA*RHOA ) + 0.0 + ( KC*RHOC )

DRDDT = RHOA*DKADT + 0.0 + RHOC*DKCDT

DRDDME = KA/GCATX*DENS DRDDIB = 0.0

DRDDMT = KC/GCATX*DENS

$

$ First factor in rate equation.

FACT1 = KS *KA/RDEN

DFAC1DT = DKSDT*KA/RDEN + KS*DKADT/RDEN - KS*KA/RDEN**2 * DRDDT

$

$ Second factor in rate equation.

FACT2 = RHOA*RHOB**0.5 - RHOC**1.5/KALJ

DFAC2DT = 0.0 + RHOC**1.5/KALJ**2 * DKALJDT

$

$ Combine terms to calculate rate and derivatives.

$

$ ---- Rate equation (rate per one gram of catalysis).

RATE = FACT1 * FACT2

$

$ ---- Rate temperature derivative.

DRDT(1) = DFAC1DT * FACT2 &

+ FACT1 * DFAC2DT

$ ---- Rate composition derivatives.

DRDX(MEOH,1) = -KS*KA/RDEN**2 * DRDDME * FACT2 &

+ FACT1 * (RHOB**0.5/GCATX*DENS)

DRDX(IBTE,1) = -KS*KA/RDEN**2 * DRDDIB * FACT2 &

+ FACT1 * (RHOA/2.0/RHOB**0.5/GCATX*DENS)

DRDX(MTBE,1) = -KS*KA/RDEN**2 * DRDDMT * FACT2 &

- FACT1 * (1.5* RHOC**0.5/GCATX/KALJ*DENS)

It is important to note, however, that the rate and rate derivatives calculated above are computedon a basis of 1 gram of catalyst . The reactive distillation algorithm requires that these values(RRATES, DRDT, and DRDX) be supplied on a unit reaction volume basis . Therefore, therate and rate derivatives are multiplied by the grams of catalyst per unit volume, GCAT.

12


15/47

$

$ -------- Convert rate equation and derivatives to a straight volume basis

$ -------- by multiplying the base rate by the grams of catalyst/unit volume.

$ -------- The rate is returned in input units, kg-moles/cubic meter/hour.

$

RRATES(1) = GCAT * RXFACT * RATE

$

DRDT(1) = GCAT * RXFACT * DRDT(1)

$ DRDX(MEOH,1) = GCAT * RXFACT * DRDX(MEOH,1)

DRDX(IBTE,1) = GCAT * RXFACT * DRDX(IBTE,1)

DRDX(MTBE,1) = GCAT * RXFACT * DRDX(MTBE,1)

RETURN

Once the column is converged, the top and bottom product compositions are known. Exchanger(HX-2B) is now simulated for heat exchange between the column feed (see HX-2A) and thebottom product (stream 7). The duty in this exchanger is set equal to the duty in exchangerHX-2A. The cooled hot side fluid is the MTBE product (stream 8).

Pump P-1 pumps the liquid distillate (stream 6) at a pressure of 827 KPa to the methanol recoverysection.

81

KeywordSyntax

HX UID=HX-2B, NAME=FEED-BTMS-B

HOT FEED=7, L=8, DP=34.5 DEFINE DUTY AS HX=HX-2A DUTY

52KeywordSyntax

PUMP UID=P-1, NAME=T-1 OVHD

FEED 6

PROD L=6P

OPER PRES=827, EFFI=65

A calculator (CONVERSION) is set up to compute the conversions of IBTE and MEOH to MTBEin the reactive distillation column itself.

121KeywordSyntax

& Calculate RXDIST conversions.

CALCULATOR UID=CONVERSION, NAME=CONVERSION OF IBTE-MEOH TO MTBE

RESULT 1 , IN - MEOH / 2 , IN - IBTE / 3 , IN - MTBE / &

4 , OUT - MEOH / 5 , OUT - IBTE / 6 , OUT - MTBE / & 20 , IBTE CONV /21 , MEOH CONV

DEFINE P(1) AS STREAM=4 RATE(M) COMP=8 $ MEOH

DEFINE P(2) AS STREAM=4 RATE(M) COMP=6 $ IBTE

DEFINE P(3) AS STREAM=4 RATE(M) COMP=7 $ MTBE







PROCEDURE

$ ----- LOAD RATES

R( 1) = P( 1)

R( 2) = P( 2)

R( 3) = P( 3)

R( 4) = P( 4) + P( 7)

R( 5) = P( 5) + P( 8)

R( 6) = P( 6) + P( 9)

$ ----- CALCULATE CONVERSION

R(20) = ( R(2) - R(5) ) / R(2)

R(21) = ( R(1) - R(4) ) / R(1)

$ ----- DISPLAY RESULTS

DISPLAY R( 1: 9 )

DISPLAY R( 20:21 )

RETURN

13


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Methanol RecoveryThe methanol recovery section of the process is shown in Figure 4.

Figure 4: Methanol Recovery Section

The methanol-C4s azeotrope (stream 6P) is delivered by pump P-1 to heat exchanger HX-3where it is cooled to 38 C against cooling water (CW). The exchanger also calculates the utility(CW) requirement given a CW delivery temperature of 16 C and a return temperature of 32 C.The cooled process stream is fed to the bottom of the water wash column (T-2).

81KeywordSyntax

HX UID=HX-3, NAME=COOLER

HOT FEED=6P, L=9, DP=34.5

OPER HTEMP=38

UTIL WATER, TIN=16, TOUT=32

79KeywordSyntax

COLUMN UID=T-2, NAME=WATER WASH

PARA TRAY=5, LLEX=25

FEED 9,5 / 10,1


PSPEC TOP=792

ESTI MODEL=SIMPLE

METHOD SET=S2

Column T-2 is simulated as a liquid-liquid extractor with 5 theoretical trays. Recirculating washwater is fed to the top of the column. A top pressure specification of 792 KPa is given. Thiscolumn uses the VLLE SRK thermodynamic set (S2) defined previously in the ThermodynamicData Category of the input file.

The raffinate leaves the top of the column (stream 11) and contains the unreacted and non-reactive C4s. The extract phase (stream 12) exits at the bottom. It enters the cold side (HX4A)of the feed-bottoms heat exchanger where it is warmed to 99 C against the recycle wash water(stream 21) which in turn is cooled (in unit HX-4B described later on).

81KeywordSyntax

HX UID=HX4A, NAME=FEED-BTMS

COLD FEED=12, L=13, DP=34.5

OPER CTEMP=99

14


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Valve V-1 drops the pressure of the heated methanol-water stream (13) to 241 KPa generatinga mixed phase stream (14) which is adiabatically flashed in unit D-1. The vapor phase (stream15) containing the dissolved hydrocarbons which have been released is vented as a flare gas;the liquid phase (stream 16) is pumped (P-2) to the methanol column to recover methanol.

53Keyword

Syntax

VALVE UID=V-1, NAME=VALVE

FEED 13

PROD M=14

OPER PRES=241

51KeywordSyntax

FLASH UID=D-1, NAME=SEPARATOR

FEED 14

PROD L=16, V=15

ADIA

52KeywordSyntax

PUMP UID=P-2, NAME=FEED PUMP

FEED 16

PROD L=17

OPER EFFI=65, PRES=690

The methanol column (T-3) is simulated with 20 theoretical trays. The feed (stream 17) enterson tray 10. The column top pressure is 138 KPa; the pressure drop through the column is 34.5KPa. A TFIX type condenser operating at 30 C and 103.5 KPa is specified. The separation ofmethanol from water is readily solved using the I/O algorithm and conventional IEG. Theperformance specifications are 99.5% recovery of methanol in the overhead product and 99.95%recovery of water in the bottoms product. Tray rating calculations are done for this column for610 mm diameter sieve trays throughout the column.

72KeywordSyntax

COLUMN UID=T-3, NAME=MEOH COLUMN

PARA TRAY=20, IO=10

FEED 17,10



DUTY 1,1 / 2,20

COND TYPE=TFIX, PRES=103.5, TEMP=30

VARY DUTY=1,2

ESTI MODEL=CONV, RRATIO=10

SPEC STRM=19, COMP= 8, RATE, DIVIDE, &

STRM=17, COMP= 8, RATE, VALUE=0.995

SPEC STRM=18, COMP=10, RATE, DIVIDE, &

STRM=17, COMP=10, RATE, VALUE=0.9995

TRATE SECTION(1)=2,19, SIEVE, DIAMETER=610

A calculator (CAL1) computes the total loss of water as a result of carry over with the C4s (stream11), the vent gas (stream 15) and by consumption in the reactor. This total quantity is the amountof make-up water required. The flowrate of the make-up water stream (MKUP) is establishedthrough a procedure call to the PRO/II stream function SRXSTR.

121KeywordSyntax

CALC UID=CAL1, NAME=MAKEUP

SEQUENCE STREAM=MKUP

DEFINE P(1) AS STRM=11, COMP=10, RATE $ H2O IN C4S

DEFINE P(2) AS STRM=15, COMP=10, RATE $ H2O IN FLARE GAS

DEFINE P(3) AS STRM=19, COMP=10, RATE $ H2O TO REACTOR

PROCEDURE

R(1) = P(1) + P(2) + P(3)

CALL SRXSTR(SMR,R(1),MKUP)

RETURN

Pump P-4 pumps the recovered wash water from the methanol column bottoms combined withmake-up water as stream 21 to heat exchanger HX4B. This unit represents the hot side of the exchangerHX-4 (see HX-4A described previously) and calculates the exit temperature for stream 22.

15


18/47

Trim cooler (HX-5) further cools the wash water (stream 22) to the desired temperature of 38 Cbefore it (stream 10) goes back to the water wash column. At this stage, the first recycle loopbetween unit T-2 (water wash column) and HX-5 (trim cooler) is closed.

The second recycle loop between unit HX-1 (feed heater) and P-3 (recycle pump) is closed whenthe pump P-3 recycles the overhead (stream 19) from the top of the methanol column (T-3) tothe reactor section.

Then, as an illustrative example, an HXRIG module is used to rigorously rate the methanolcolumn condenser. This rigorous heat exchanger is modeled as an attached heat exchanger tocolumn T-3. This unit takes as its input the exchanger’s mechanical data such as shell and tubedimensions, tube layout pattern, the baffle cut and shell and tube side nozzle sizes. A foulingfactor of 0.00035 m

2-K/kW is used for the condenser cooling water side. The ZONES option is

selected to determine where phase changes occur in the exchanger. An extended data sheet isprinted in the output.

52KeywordSyntax

PUMP UID=P-4, NAME=WATER PUMP

FEED 18,MKUP

PROD L=21


81Keyword

Syntax

HX UID=HX4B, NAME=FEED-BOTS

HOT FEED=21, L=22, DP=34.5

DEFINE DUTY AS HX=HX4A, DUTY

81KeywordSyntax


HOT FEED=22, L=10, DP=34.5

OPER HTEMP=38

52KeywordSyntax

PUMP UID=P-3, NAME=RECYCLE PUMP

FEED 19

PROD L=20


82KeywordSyntax

HXRIG UID=RC-1, NAME=T-3 COND

TYPE TEMA=AES

SHELL ID=381

TUBES OD=19, BWG=14, LENGTH=4.75, PASS=2, &

PATTERN=90, PITCH=25.4, FOUL=0.00035, FEED=CW, L=WOUT

BAFFLE CUT=0.18

TNOZZLE ID=102, 102

SNOZZLE ID=152, 102

PRINT EXTENDED , ZONES

ATTACH COLUMN=T-3, TYPE=CONDENSER

Finally, the beginning and ending units for the two recycle loops are defined, and the Wegsteinrecycle acceleration method is chosen to speed up the convergence.

134KeywordSyntax

RECYCLE DATA

ACCEL TYPE=WEGS

LOOP NO=1, START=T-2, END=HX-5

LOOP NO=2, START=HX-1, END=P-3

16


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Technical Results

The overall mole balance for a 200,000 metric tonne per day MTBE plant using the reactivedistillation process is shown in Table 5.

Table 5: Overall Mole Balance for a 200,000 TPY MTBE Plant (Ethermax Process) (kg-mol/hr)

Material FEEDS PRODUCTSC4s Feed Methanol Water

MakeupMTBE

ProductUnreacted

C4sFlare Gas

N-butane 76.50 ----- ----- trace 76.50 0.003

Iso-butane 348.50 ----- ----- ----- 348.49 0.012

1-butene 59.50 ----- ----- ----- 59.50 trace

cis 2-butene 34.00 -------- -------- trace 34.00 trace

trans 2-butene 51.00 -------- -------- trace 51.00 trace

Isobutene (IBTE) 280.50 -------- -------- -------- 2.26 --------

MTBE -------- -------- -------- 277.35 trace --------

Methanol -------- 277.5 -------- 0.11 trace 0.001

tert-butanol -------- -------- -------- 0.19 -------- --------

Water -------- -------- 0.61 -------- 0.41 0.011

Di-isobutylene -------- -------- -------- 0.35 -------- --------

TOTAL 850.00 277.5 0.61 278.00 572.16 0.03

Results Analysi s

The results of this simulation shown above indicate that the overall conversion of IBTE is 99.2%

with a selectivity to MTBE of 99.7%. In the reactive distillation column itself, 87.2% of the IBTEfed to the column is converted to MTBE. The MTBE product is 99.77% pure and needs no furtherpurification.

There are a number of factors that affect the overall conversion rate of IBTE. Some of these are:

Methanol to IBTE ratio

Number of reaction trays

Type of catalyst used

Note, however, that while the IBTE conversion in the conversion reactors increase as theMEOH:IBTE ratio is increased, the overall IBTE conversion reaches a maximum, then decreasesas the MEOH:IBTE ratio is increased. This is due to the fact that more MTBE product is carriedupward through the column stripping section into the reaction trays. This promotes the reverse

reaction of MTBE to methanol and IBTE, thus reducing the overall conversion of IBTE.

Output Resul ts

Selected results are attached. These include reactor RX-1, rigorous exchanger RC-1 zonesanalysis, MTBE column T-1 (reactive distillation), tray rating results for methanol column T-3,and stream molar component rates for selected streams.

17


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Additi onal References

1. Hydrocarbon Processing, Vol. 61, No. 9, p.177, Sept. 1982.

2. Bitar, L.S., E. A. Hazbun, and W. J. Piel, MTBE Production and Economics, HydrocarbonProcessing, Vol. 63, No. 10, pp. 63-68, Oct. 1984.

3. Hutson, T., et al ., in ‘‘Handbook of Chemicals Production Processes’’, Ed. Robert A. Meyers,

McGraw-Hill Book Company, New York, Chap. 1.12, 1986.

4. Friedlander, R.H., in ‘‘Handbook of Chemicals Production Processes’’, Ed. Robert A.Meyers, McGraw-Hill Book Company, New York, Chap. 1.13, 1986.

5. Jacobs, R., and R. Krishna, 1993, Multiple Solutions in Reactive Distillation of Methyltert-Butyl Ether Synthesis, Ind. Chem Res., 32(8).

6. Hydrocarbon Processing, Vol. 69, No. 10, pp.29,31,33,44, Oct. 1990.

7. Oil & Gas J., Mar. 25, 1991, pp.26-29.

8. Shah, V.B., D. Bluck, J. W. Kovach III, R. Parikh, and R. Yu, 1994, The Sensitivity of theDesign and Operability of the MTBE Processs with Respect to Changes in ReactionParameters and Process Configurations, paper presented at the Refining LNG and Petro-chemasia 94 Conference in Singapore, December 7-8 1994.

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Appendix A

Keyword Input File ---- Reactive Distillation (Ethermax) Process

TITLE PROJECT = MTBECASEBOOK , &

PROBLEM = MTBE PLANT , &

USER = SIMSCI , &

DATE = Mar95

DIMENSION SI, TEMP=C

PRINT INPUT = ALL , &

STREAM = COMPONENT , &

MBAL

SEQUENCE HX-1 , RX-1, HX-2A , &

CAL0 , T-1 , CONVERSION , &

HX-2B , P-1 , HX-3 , &

T-2 , HX4A , V-1 , D-1 , P-2 , T-3 , &

CAL1 , P-4 , HX4B , HX-5 , P-3 , &

RC-1

COMP DATA

LIBID 1,NC4 / & $ N-BUTANE 2,IC4 / & $ I-BUTANE

3,1BUTENE / & $ BUTENE-1

4,BTC2 / & $ CIS BUTENE-2

5,BTT2 / & $ TRANS BUTENE-2

6,IBTE / & $ ISO BUTENE

7,MTBE / & $ METHYL TERTIARY BUTYL ETHER

8,MEOH / & $ METHANOL

9,TBA / & $ TERT BUTYL ALCOHOL

10,H2O / & $ WATER

11,244TM1P,,DIB $ DI-ISO BUTYLENE & ISOMERS

THERMO DATA

METHOD SYSTEM=SRKM, TRANSPORT=PURE, SET=S1

KVAL

SRKM 1, 9, 0.046973, 0.126027,0,0,0,0,1,1

SRKM 3, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 4, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 5, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 6, 8, 0.135525,-0.032271,0,0,0,0,1,1

SRKM 8, 9,-0.073971,-0.055222,0,0,0,0,1,1

SRKM 9,10,-0.145000,-0.253000,0,0,0,0,1,1

SRKM 7,11, 0.05785, -0.0093,-10.144,6.17,0,0,1,1

METHOD SYSTEM(VLLE)=SRKM, L1KEY=1, L2KEY=10, SET=S2

KVAL

SRKM 1, 9, 0.046973, 0.126027,0,0,0,0,1,1

SRKM 3, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 4, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 5, 8, 0.136,-0.0323,0,0,0,0,1,1

SRKM 6, 8, 0.135525,-0.032271,0,0,0,0,1,1

SRKM 8, 9,-0.073971,-0.055222,0,0,0,0,1,1

SRKM 9,10,-0.145000,-0.253000,0,0,0,0,1,1

SRKM 7,11, 0.05785, -0.0093,-10.144,6.17,0,0,1,1

STREAM DATA

19


22/47

PROP STRM= 1, TEMP=16, PRES=1620, COMP=8,277.5

PROP STRM= 2, TEMP=16, PRES=1620, COMP=9/41/7/4/6/33, &

RATE=850, NORMALIZE

PROP STRM=10, TEMP=38, PRES=793, COMP=10,375

PROP STRM=20, TEMP=44, PRES=1724, COMP=8,4.0/10,0.3

$

$ INCREASE MTBE COLUMN CONDENSER COOLING WATER FLOWRATE

$

$ PROP STRM=CW, TEMP=21, PRES=690, COMP=10,100, RATE(V)=75 PROP STRM=CW, TEMP=21, PRES=690, COMP=10,100, RATE(V)=175

PROP STRM=MKUP, TEMP=38, PRES=350, COMP=10,500

NAME 1, MEOH FEED / 2, OLEFINS / 20, MEOH RECYC / &

6, T-1 OVHD / 8, MTBE / 11, C4’S / &

15, FLARE GAS / MKUP,MKUP WATER

RXDATA

$

$ Reaction Data for Reactors

$

RXSET ID=ST1

REACTION ID=1

STOIC 6,-2 / 11,1 $ IBTE + IBTE = DIB

REACTION ID=2

STOIC 10,-1 / 6,-1 / 9,1 $ H2O + IBTE = TBA

REACTION ID=3

STOIC 6,-1 / 8,-1 / 7,1 $ IBTE + MEOH = MTBE

$

$ ======================================================================

$ = =

$ = Reaction Data =

$ = =

$ = Column Reaction Data =

$ ======================================================================

$ $

$ ==================================================

$

$ MTBE REACTION SET - Supplemented Al-Jarallah

$

$ Iso-butane+Methanol - MTBE

$

RXSET ID=ALJX

REACTION ID=ALJ0

STOICH 6, -1/8, -1/7, 1

BASE COMP=8

KINETIC PROCEDURE=ALJD, POSITION=1

$

20


23/47

$ ======================================================================

$ = =

$ = PROCEDURE DATA =

$ = =

$ ======================================================================

$

PROCEDURE DATA

$ ======================================================================

$ = =

$ = PROCEDURE DATA for RXKINETIC REACTIONS =

$ = (Column Reaction PROCEDURES) =

$ = =

$ ======================================================================

$

$ ==================================================

$ ==================================================

$ ==================================================

$

$ Al-Jarallah MTBE Column Reaction Kinetics.

$

$ ==================================================

$ ==================================================

$ ==================================================

$

$

$

$ Also modified to remove catalyst based concentration

$ from reaction expression. To revert to paper, set

$ GCATX = GCAT. This will drop the reaction rate to

$ way below what seems realistic based on literature

$ data. As is, it is still low.

$

PROCEDURE(RXKINE) ID=ALJD,NAME=Al-Jarallah

$

$ Reference: Adnan M. Al-Jarallah, Mohammed A. B. Siddiqui, and

$ A. K. K. Lee, ‘‘Kinetics of Methyl Tertiary Butyl $ Ether Synthesis Catalyzed by Ion Exchange Resin"

$ Canadian Journal of Chemical Engineering (66)

$ pp. 802-807

$

PDATA GCAT , RXFACT

REAL KS , KA , KC , KALJ , KREH1 , KREH2 , KIZQ , KEQREF

INTEGER IBTE , MEOH , MTBE

CODE

$

$ INITIALIZE DATA:

$ SET INDEXES FOR COMPONENTS

$ DEFINE GAS CONSTANT IN Joules/gm-mole K

$ Note: R could have been retrieved in input units by R=RGAS.

$ However, since the reaction basis won’t change, and

$ RGAS will change with the default units, this

$ eliminates one possible source of error..

$ Initialize the local variable TK to the absolute temperature.

$ Note: The temperature basis for the flowshet must be Centigrade

$ or Kelvin.

$ Set temperature and composition derivatives to zero.

$

IBTE = 6

MTBE = 7

MEOH = 8

$

R = 8.314

21


24/47

$

TK = RTABS

$

DO 1000 I1 = 1,NOR

DRDT(I1) = 0.0

DO 1000 I2 = 1,NOC

1000 DRDX(I2,I1) = 0.0

$

$ Calculate the surface reaction rate constant, ks, and the $ equilibrium adsorption constants Ka and Kb. The activation

$ energy is in J/gm-mole.

$ units: ks - (gm-mole / gm catalyst)**1.5 /hour

$ Ka - gm-catalyst / mole

$ Kc - gm-catalyst / mole

$

KS = 1.2E+13*EXP(-87900.0/(R*TK))

KA = 5.1E-13*EXP( 97500.0/(R*TK))

KC = 1.6E-16*EXP(119000.0/(R*TK))

$

DKSDT = KS * 87900.0 / R / (TK*TK)

DKADT = KA * (-1.0) * 97500.0 / R / (TK*TK)

DKCDT = KC * (-1.0) * 119000.0 / R / (TK*TK)

$

$ -------- Calculate the equilibrium constant.

$

$ Units - (gm-moles/gm-catalyst)/hour

$ Phase - Liquid Phase Reaction

$ Catalyst - Ion Exchange Resin Amberlyst 15,

$ the equilibrium should be independant of the catalyst

$

$

$ ---- METHOD 1.0: Adnan M. Al-Jarallah, Mohammed A. B. Siddiqui, and

$ A. K. K. Lee, ‘‘Kinetics of Methyl Tertiary Butyl

$ Ether Synthesis Catalyzed by Ion Exchange Resin"

$ Canadian Journal of Chemical Engineering (66)

$ pp. 802-807

$

KALJ = EXP(-17.31715+(7196.776/TK)) $

DKALJDT = - KALJ * 7196.776 / (TK*TK)

$

$ Bulk concenrations of components per gram of catalyst, XLCONC is

$ in moles/flow volume. XLCONC will be passed to the procedure

$ in user input units. Internally to PRO/II, it is in SI units

$ (kg-mole/cubic meter). The basis for these reaction equations

$ is gm-moles/liter. The conversion factor from input units of

$ kg-moles/cubic meter to the reaction basis of gm-moles/liter

$ is one. Therefore, XLCONC can be used with no conversion.

$

$

$ RHOA=(XLCONC(MEOH)/GCAT) |-This should be equivalent to below.

$ RHOB=(XLCONC(IBTE)/GCAT) | It has been written explicitly below

$ RHOC=(XLCONC(MTBE)/GCAT) | to make it obvious how to do the

$ analytical derivatives.

$

$ Calculate density in moles / volume

$

GCATX = 12.4

DENS=RLMRAT/RLVRAT

RHOA=(XLIQ(MEOH)*DENS/GCATX)

RHOB=(XLIQ(IBTE)*DENS/GCATX)

RHOC=(XLIQ(MTBE)*DENS/GCATX)

22


25/47

$

$ -------- Calculate reaction rate and derivatives by terms

$ -------- Units - RATE - gram-mole / gram catalyst / hr.

$

$ Denominator & derivatives.

$

RDEN = 1.0 + ( KA*RHOA ) + 0.0 + ( KC*RHOC )

DRDDT = RHOA*DKADT + 0.0 + RHOC*DKCDT

DRDDME = KA/GCATX*DENS DRDDIB = 0.0

DRDDMT = KC/GCATX*DENS

$

$ First factor in rate equation.

FACT1 = KS *KA/RDEN

DFAC1DT = DKSDT*KA/RDEN + KS*DKADT/RDEN - KS*KA/RDEN**2 * DRDDT

$

$ Second factor in rate equation.

FACT2 = RHOA*RHOB**0.5 - RHOC**1.5/KALJ

DFAC2DT = 0.0 + RHOC**1.5/KALJ**2 * DKALJDT

$

$ Combine terms to calculate rate and derivatives.

$

$ ---- Rate equation (rate per one gram of catalysis).

RATE = FACT1 * FACT2

$

$ ---- Rate temperature derivative.

DRDT(1) = DFAC1DT * FACT2 &

+ FACT1 * DFAC2DT

$ ---- Rate composition derivatives.

DRDX(MEOH,1) = -KS*KA/RDEN**2 * DRDDME * FACT2 &

+ FACT1 * (RHOB**0.5/GCATX*DENS)

DRDX(IBTE,1) = -KS*KA/RDEN**2 * DRDDIB * FACT2 &

+ FACT1 * (RHOA/2.0/RHOB**0.5/GCATX*DENS)

DRDX(MTBE,1) = -KS*KA/RDEN**2 * DRDDMT * FACT2 &

- FACT1 * (1.5* RHOC**0.5/GCATX/KALJ*DENS)

$

$ -------- Convert rate equation and derivatives to a straight volume basis $ -------- by multipling the base rate by the grams of catalyst/unit volume.

$ -------- The rate is returned in input units, kg-moles/cubic meter/hour.

$

RRATES(1) = GCAT * RXFACT * RATE

$

DRDT(1) = GCAT * RXFACT * DRDT(1)

$

DRDX(MEOH,1) = GCAT * RXFACT * DRDX(MEOH,1)

DRDX(IBTE,1) = GCAT * RXFACT * DRDX(IBTE,1)

DRDX(MTBE,1) = GCAT * RXFACT * DRDX(MTBE,1)

RETURN

UNIT OPS

HX UID=HX-1, NAME=FEED HEAT

COLD FEED=1,2,20, L=3, DP=34.5

OPER CTEMP=43.5

CONREACTOR UID=RX-1, NAME=REACTORS

FEED 3

PROD L=4

OPER TEMP=55, DP=69

RXCALC MODEL=STOIC

RXSTOIC RXSET=ST1

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REACTION 1

BASE COMP=6

CONV 0.0025

REACTION 2

BASE COMP=10

CONV 1.00

REACTION 3

BASE COMP=8

CONV 0.93 $

$ Provide storage location (RESULT(1))

$ Note: RXFACT is not varied in this casebook,

$ but is set equal to 1.0 always

$

CALCULATOR UID=CAL0, NAME=COPY RXFACT

PROCEDURE

IF (R(2) .NE. 1.0) R(1) = 1.0 $Set RXFACT TO 1 on first call.

R(2) = 1.0

RETURN

HX UID=HX-2A, NAME=FEED-BTMS-A


OPER CTEMP=72

$

$ Reactive Distillation.

COLUMN UID=T-1, NAME=MTBE COLUMN

PARA TRAY=30, CHEM=35

FEED 5, 15



COND TYPE=TFIX, PRES=621, TEMP=43.5

DUTY 1,1 / 2,30

VARY DUTY=1,2

SPEC STRM=7,RATE,VALUE=278.0

SPEC RRATIO, VALUE=1.1

PRINT PROP=ALL , COMP=M

PLOT LOG XCOMP=6,6/ 8, 8/ 7, 7/1,1

ESTI MODEL=SIMPLE

RXTRAY ALJX, 8 , 13

LVOL(M3) 8 , 5.0 / 13, 5.0

DEFINE GCAT AS 360.0

DEFINE RXFACT AS 1.0

TSIZE VALVE FF=80.0 DPCALC=0.0

$

$ Calculate RXDIST conversions.

CALCULATOR UID=CONVERSION, NAME=CONVERSION OF IBTE-MEOH TO MTBE

RESULT 1 , IN - MEOH / 2 , IN - IBTE / 3 , IN - MTBE / &

4 , OUT - MEOH / 5 , OUT - IBTE / 6 , OUT - MTBE / &

20 , IBTE CONV /21 , MEOH CONV










24


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PROCEDURE

$ ----- LOAD RATES

R( 1) = P( 1)

R( 2) = P( 2)

R( 3) = P( 3)

R( 4) = P( 4) + P( 7)

R( 5) = P( 5) + P( 8)

R( 6) = P( 6) + P( 9)

$ ----- CALCULATE CONVERSION R(20) = ( R(2) - R(5) ) / R(2)

R(21) = ( R(1) - R(4) ) / R(1)

$ ----- DISPLAY RESULTS

DISPLAY R( 1: 9 )

DISPLAY R( 20:21 )

RETURN

HX UID=HX-2B, NAME=FEED-BTMS-B

HOT FEED=7, L=8, DP=34.5

DEFINE DUTY AS HX=HX-2A DUTY

PUMP UID=P-1, NAME=T-1 OVHD

FEED 6

PROD L=6P



HOT FEED=6P, L=9, DP=34.5

OPER HTEMP=38

UTIL WATER, TIN=16, TOUT=32

COLUMN UID=T-2, NAME=WATER WASH

PARA TRAY=5, LLEX=25

FEED 9,5 / 10,1


PSPEC TOP=792

ESTI MODEL=SIMPLE

METHOD SET=S2

HX UID=HX4A, NAME=FEED-BTMS


OPER CTEMP=99

VALVE UID=V-1, NAME=VALVE

FEED 13

PROD M=14

OPER PRES=241

FLASH UID=D-1, NAME=SEPARATOR

FEED 14

PROD L=16, V=15

ADIA

PUMP UID=P-2, NAME=FEED PUMP

FEED 16

PROD L=17


COLUMN UID=T-3, NAME=MEOH COLUMN

PARA TRAY=20, IO=10

FEED 17,10



DUTY 1,1 / 2,20

25


28/47

COND TYPE=TFIX, PRES=103.5, TEMP=30

VARY DUTY=1,2

ESTI MODEL=CONV, RRATIO=10

SPEC STRM=19, COMP= 8, RATE, DIVIDE, &

STRM=17, COMP= 8, RATE, VALUE=0.995

SPEC STRM=18, COMP=10, RATE, DIVIDE, &

STRM=17, COMP=10, RATE, VALUE=0.9995

TRATE SECTION(1)=2,19, SIEVE, DIAMETER=610

CALC UID=CAL1, NAME=MAKEUP

SEQUENCE STREAM=MKUP

DEFINE P(1) AS STRM=11, COMP=10, RATE $ H2O IN C4’S

DEFINE P(2) AS STRM=15, COMP=10, RATE $ H2O IN FLARE GAS

DEFINE P(3) AS STRM=19, COMP=10, RATE $ H2O TO REACTOR

PROCEDURE

R(1) = P(1) + P(2) + P(3)

CALL SRXSTR(SMR,R(1),MKUP)

RETURN

PUMP UID=P-4, NAME=WATER PUMP

FEED 18,MKUP

PROD L=21


HX UID=HX4B, NAME=FEED-BOTS

HOT FEED=21, L=22, DP=34.5

DEFINE DUTY AS HX=HX4A, DUTY


HOT FEED=22, L=10, DP=34.5

OPER HTEMP=38

PUMP UID=P-3, NAME=RECYCLE PUMP

FEED 19

PROD L=20


HXRIG UID=RC-1, NAME=T-3 COND TYPE TEMA=AES

$

$ SIZE FOR UNFINNED TUBES

$

SHELL ID=381

TUBES OD=19, BWG=14, LENGTH=5.75, PASS=2, &

PATTERN=90, PITCH=25.4, FOUL=0.00035, FEED=CW, L=WOUT

BAFFLE CUT=0.18

TNOZZLE ID=102, 102

SNOZZLE ID=152, 102

PRINT EXTENDED , ZONES

ATTACH COLUMN=T-3, TYPE=CONDENSER

RECYCLE DATA

ACCEL TYPE=WEGS

LOOP NO=1, START=T-2, END=HX-5

LOOP NO=2, START=HX-1, END=P-3

26


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APPENDIX B

Output File ---- Reactive Distillation (Ethermax) Process

The following are selected exerpts from the PRO/II output report. The complete output isavailable from SimSci on floppy disk.

SIMULATION SCIENCES INC. R PAGE P-50

PROJECT MTBECASEBOOK PRO/II VERSION 4.02 386/EM

PROBLEM MTBE PLANT OUTPUT SIMSCI CONVERSION REACTOR SUMMARY Mar95

==============================================================================

UNIT 2, ’RX-1’, ’REACTORS’

OPERATING CONDITIONS

REACTOR TYPE ISOTHERMAL REACTOR

DUTY, M*KJ/HR -12.3321

TOTAL HEAT OF REACTION AT 25.00 C, M*KJ/HR -19.6827

INLET OUTLET

--------------------- ---------------------

FEED 3 LIQUID PRODUCT 4

TEMPERATURE, C 43.50 55.00

PRESSURE, KPA 1585.5000 1516.5000

REACTION DATA

----------------- RATES, KG-MOL/HR -------------------- FRACTION

COMPONENT FEED CHANGE PRODUCT CONVERTED

------------------------------------ --------------------- --------------------- --------------------- ---------------------

1 NC4 76.5019 .0000 76.5019

2 IC4 348.5030 .0000 348.5030

3 1BUTENE 59.5000 .0000 59.5000

4 BTC2 34.0001 .0000 34.0001

5 BTT2 51.0000 .0000 51.0000

6 IBTE 280.5000 -262.8161 17.6839 .9370

7 MTBE 2.22240E-05 261.9277 261.9277

8 MEOH 281.6427 -261.9277 19.7150 .9300

9 TBA 4.49482E-13 .1871 .1871

10 H2O .1871 -.1871 .0000 1.0000

11 DIB .0000 .3506 .3506

TOTAL 1131.8350 -262.4655 869.3694

KG-MOL/HR FRACTION

BASE COMPONENT REACTION CONVERTED CONVERTED(1)

------------------------------------ --------------------- --------------------- ------------------------

6 IBTE 1 .7013 2.50000E-03

10 H2O 2 .1871 1.0000 8 MEOH 3 261.9277 .9300

(1) FRACTION CONVERTED BASED ON AMOUNT IN FEED

27


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PROBLEM MTBE PLANT OUTPUT SIMSCI

CONVERSION REACTOR SUMMARY Mar95

==============================================================================

UNIT 2, ’RX-1’, ’REACTORS’ (CONT)

REACTOR MASS BALANCE

--------------------- RATES, KG/HR ------------------------ FRACTION

COMPONENT FEED CHANGE PRODUCT CONVERTED

------------------------------------ --------------------- --------------------- --------------------- ---------------------

1 NC4 4446.5970 .0000 4446.5970

2 IC4 20256.3900 .0000 20256.3900

3 1BUTENE 3338.4280 .0000 3338.4280

4 BTC2 1907.6760 .0000 1907.6760

5 BTT2 2861.5090 .0000 2861.5090

6 IBTE 15738.2900 -14746.0800 992.2104 .9370

7 MTBE 1.95902E-03 23088.6700 23088.6700

8 MEOH 9024.3950 -8392.6870 631.7076 .9300

9 TBA 3.33174E-11 13.8712 13.8712

10 H2O 3.3712 -3.3712 .0000 1.0000 11 DIB .0000 39.3450 39.3450

TOTAL 57576.6600 -.2617 57576.4000

28


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RIGOROUS HEAT EXCHANGER SUMMARY Mar95

==============================================================================

UNIT 21, ’RC-1’, ’T-3 COND’

HEAT EXCHANGER IS ATTACHED TO COLUMN T-3, UNIT 15 AS A CONDENSER OPERATING CONDITIONS OVERALL

---------------------

DUTY, M*KJ/HR 3.9720

LMTD, C 42.683

MTD, C 36.858

F FACTOR, (FT) .864

U*A, KW/K 29.935

U, KW/M2-K .876 .809 (REQD)

A, M2 36.981 34.160 (REQD)

SHELL SIDE CONDITIONS INLET OUTLET

--------------------- ---------------------

STREAM IS FROM COLUMN T-3 , UNIT 15

VAPOR, KG-MOL/HR 98.803 N/A K*KG/HR 3.109 N/A

CP, KJ/KG-C 1.520 N/A

LIQUID, KG-MOL/HR N/A 98.803

K*KG/HR N/A 3.109

CP, KJ/KG-C N/A 2.538

TOTAL, KG-MOL/HR 98.803 98.803

K*KG/HR 3.109 3.109

CONDENSATION, KG-MOL/HR 98.803

L/F .0000 1.0000


PRESSURE, KPA 138.000 91.775

TUBE SIDE CONDITIONS INLET OUTLET

--------------------- ---------------------

FEED(S) CW

PRODUCTS LIQUID WOUT

VAPOR, KG-MOL/HR N/A N/A

K*KG/HR N/A N/A

CP, KJ/KG-C N/A N/A

LIQUID, KG-MOL/HR 9700.201 9700.201

K*KG/HR 174.749 174.749

CP, KJ/KG-C 4.499 4.457

TOTAL, KG-MOL/HR 9700.201 9700.201

K*KG/HR 174.749 174.749

VAPORIZATION, KG-MOL/HR N/A

L/F 1.0000 1.0000


PRESSURE, KPA 690.000 318.172

29


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==============================================================================

SHELL AND TUBE EXCHANGER DATA SHEET FOR EXCHANGER ’RC-1’

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I EXCHANGER NAME T-3 COND UNIT ID RC-1 I I SIZE 381 - 5750 TYPE AES, HORIZONTAL CONNECTED 1 PARALLEL 1 SERIES I

I AREA/UNIT 37. M2 ( 34. M2 REQUIRED) AREA/SHELL 37. M2 I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I PERFORMANCE OF ONE UNIT SHELL-SIDE TUBE-SIDE I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I FEED STREAM ID CW I

I FEED STREAM NAME (ATTACHED) I

I TOTAL FLUID KG/HR 3109. 174749. I

I VAPOR (IN/OUT) KG/HR 3109. / / I

I LIQUID KG/HR / 3109. 174749. / 174749. I

I STEAM KG/HR / / I

I WATER KG/HR / / I

I NON CONDENSIBLE KG/HR I

I TEMPERATURE (IN/OUT) DEG C 74.1 / 27.2 21.0 / 26.2 I

I PRESSURE (IN/OUT) KPA 138.00 / 91.78 690.00 / 318.17 I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I SP. GR., LIQ (4C / 4C H2O) / .800 1.000 / 1.000 I

I VAP (4C / 4C AIR) 1.087 / / I

I DENSITY, LIQUID KG/M3 / 787.360 993.997 / 989.495 I

I VAPOR KG/M3 1.538 / / I

I VISCOSITY, LIQUID PAS / 5.5E-04 9.8E-04 / 8.7E-04 I

I VAPOR PAS 1.1E-05 / / I

I THRML COND,LIQ W/M-K / .2003 .6051 / .6121 I

I VAP W/M-K .0192 / / I

I SPEC.HEAT,LIQUID KJ/KG-K / 2.5378 4.4992 / 4.4567 I

I VAPOR KJ/KG-K 1.5205 / / I

I LATENT HEAT KJ/KG 1157.83 I

I VELOCITY M/SEC .16 5.23 I

I DP/SHELL KPA 46.25 371.85 I I FOULING RESIST M2-K/KW .35222 ( .44648 REQD) .00035 I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I TRANSFER RATE KW/M2-K SERVICE .88 ( .81 REQD), CLEAN 1.27 I

I HEAT EXCHANGED M*KJ/HR 3.972 MTD(CORRECTED) 36.9 FT .864 I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I CONSTRUCTION OF ONE SHELL SHELL-SIDE TUBE-SIDE I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I DESIGN PRESSURE KPA 2068. 2068. I

I NUMBER OF PASSES 1 2 I

I MATERIAL CARB STL CARB STL I

I INLET NOZZLE ID MM 152.0 102.0 I

I OUTLET NOZZLE ID MM 102.0 102.0 I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I TUBE: NUMBER 109 OD 19.000 MM BWG 14 LENGTH 5.8 M I

I TYPE BARE PITCH 25.4 MM PATTERN 90 DEGREES I

I SHELL: ID 381.00 MM SEALING STRIPS 0 PAIRS I

I BAFFLE: CUT .180 SPACING (IN/CENT/OUT): MM 93.70/ 76.20/ 93.70,SINGLE I

I RHO-V2: INLET NOZZLE 1473.0 KG/M-SEC2 I

I TOTAL WEIGHT/SHELL,KG 1007.4 FULL OF WATER 2655.4 BUNDLE 1062.8 I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

30


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==============================================================================

SHELL AND TUBE EXTENDED DATA SHEET FOR EXCHANGER ’RC-1’

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I EXCHANGER NAME T-3 COND UNIT ID RC-1 I

I SIZE 381 - 5750 TYPE AES, HORIZONTAL CONNECTED 1 PARALLEL 1 SERIES I

I AREA/UNIT 37. M2 ( 34. M2 REQUIRED) I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I PERFORMANCE OF ONE UNIT SHELL-SIDE TUBE-SIDE I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I FEED STREAM ID CW I

I FEED STREAM NAME (ATTACHED) I

I WT FRACTION LIQUID (IN/OUT) .000 / 1.000 1.000 / 1.000 I

I REYNOLDS NUMBER 52994. 81759. I

I PRANDTL NUMBER 5.045 6.936 I

I WATSON K,LIQUID / 10.599 8.762 / 8.762 I

I VAPOR 10.599 / / I

I SURFACE TENSION N/M / .024 .072 / .072 I

I FILM COEF(SCL) KW/M2-K 1.9 (1.000) 15.6 (1.000) I I FOULING LAYER THICKNESS MM .000 .000 I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I THERMAL RESISTANCE I

I UNITS: ( M2-K/KW ) (PERCENT) (ABSOLUTE) I

I SHELL FILM 52.00 .52123 I

I TUBE FILM 8.24 .08260 I

I TUBE METAL 4.58 .04593 I

I TOTAL FOULING 35.18 .35267 I

I ADJUSTMENT 8.26 .08280 I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I PRESSURE DROP SHELL-SIDE TUBE-SIDE I

I UNITS: (KPA) (PERCENT) (ABSOLUTE) (PERCENT) (ABSOLUTE)I

I WITHOUT NOZZLES 97.00 44.87 76.94 286.11 I

I INLET NOZZLES 2.95 1.36 8.46 31.48 I

I OUTLET NOZZLES .05 .02 14.59 54.27 I

I TOTAL /SHELL 46.25 371.85 I

I TOTAL /UNIT 46.25 371.85 I

I DP SCALER 1.00 1.00 I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I CONSTRUCTION OF ONE SHELL I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I TUBE:OVERALL LENGTH 5.8 M EFFECTIVE LENGTH 5.33 M I

I TOTAL TUBESHEET THK 66.0 MM AREA RATIO (OUT/IN) 1.285 I

I THERMAL COND 51.9 W/M-K DENSITY 7862.00 KG/M3I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I BAFFLE: THICKNESS 4.762 MM NUMBER 74 I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

I BUNDLE: DIAMETER 327.0 MM TUBES IN CROSSFLOW 92 I

I CROSSFLOW AREA .010 M2 WINDOW AREA .012 M2 I

I WINDOW HYD DIA 40.63 MM I

I TUBE-BFL LEAK AREA .002 M2 SHELL-BFL LEAK AREA .001 M2 I

I--------------------------------------------------------------------------------------------------------------------------------------------------------I

31


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==============================================================================

ZONE ANALYSIS FOR EXCHANGER ’RC-1’

TEMPERATURE - PRESSURE SUMMARY

---------------- TEMPERATURE, C ------------- ---------------- PRESSURE, KPA -------------

SHELL-SIDE TUBE-SIDE SHELL-SIDE TUBE-SIDE

ZONE IN OUT IN OUT IN OUT IN OUT

-------- ------------- ------------- ------------- ------------- ------------- ------------- ------------- -------------

1 74.1 69.6 21.6 26.2 138.0 122.6 643.4 318.2

2 69.6 65.0 21.4 21.6 122.6 107.2 658.7 643.4

3 65.0 60.5 21.4 21.4 107.2 91.8 663.8 658.7

4 60.5 27.2 21.0 21.4 91.8 91.8 690.0 663.8

HEAT TRANSFER AND PRESSURE DROP SUMMARY

------------ HEAT TRANSFER --------- PRESSURE DROP (TOTAL) - FILM COEFFICIENT -

MECHANISM KPA KW/M2-K ZONE SHELL-SIDE TUBE-SIDE SHELL-SIDE TUBE-SIDE SHELL-SIDE TUBE-SIDE

-------- ------------------------ ------------------------ -------------------- ----------------- -------------------- -----------------

1 CONDENSATION LIQ. HEATING 15.408 325.273 2.998 15.917

2 CONDENSATION LIQ. HEATING 15.408 15.245 1.405 15.310

3 CONDENSATION LIQ. HEATING 15.408 5.090 .656 15.179

4 LIQ. SUBCOOL LIQ. HEATING .000 26.220 .478 15.088

-------------------- -----------------

TOTAL PRESSURE DROP 46.225 371.828

HEAT TRANSFER SUMMARY (CONT)

------------ DUTY ------------- U-VALUE AREA LMTD FT

ZONE M*KJ/HR PERCENT KW/M2-K M2 C

-------- ----------------- ------------- ------------------------ -------------------- ----------------- ----------------

1 3.47 87.48 1.23 18.96 47.91 .864

2 .16 4.10 .84 1.37 45.71 .864

3 .05 1.37 .50 .85 41.32 .864

4 .28 7.05 .39 12.98 17.89 .864

----------------- ------------- ------------------------ -------------------- ----------------- ----------------

TOTAL 3.97 100.00 34.16

WEIGHTED .88 42.68 .864

OVERALL 20.42 .864

INSTALLED 36.98

TOTAL DUTY = (WT. U-VALUE) (TOTAL AREA) (WT. LMTD) (OVL. FT)

ZONE DUTY = (ZONE U-VALUE) (ZONE AREA) (ZONE LMTD) (OVL. FT)

32


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COLUMN SUMMARY Mar95

==============================================================================

UNIT 5, ’T-1’, ’MTBE COLUMN’

TOTAL NUMBER OF ITERATIONS

CHEM METHOD 38

COLUMN SUMMARY

-------------------- NET FLOW RATES --------------------- HEATER

TRAY TEMP PRESSURE LIQUID VAPOR FEED PRODUCT DUTIES

DEG C KPA KG-MOL/HR M*KJ/HR

------------ ------------- ---------------- ---------------- ---------------- ----------------- ----------------- ------------------------

1C 43.5 621.00 633.5 575.9L -23.5395

2 50.8 621.00 661.3 1209.5

3 51.5 623.73 659.0 1237.2

4 52.0 626.46 657.6 1235.0 5 52.3 629.20 656.4 1233.6

6 52.7 631.93 654.5 1232.3

7 53.1 634.66 650.4 1230.5

8 53.8 637.39 633.1 1226.3

9 54.8 640.12 610.5 1211.6

10 56.5 642.86 578.0 1191.6

11 59.4 645.59 534.9 1161.9

12 63.8 648.32 489.4 1121.9

13 68.7 651.05 458.5 1079.8

14 73.3 653.79 441.1 1049.8

15 76.7 656.52 1202.6 1032.5 869.4M

16 90.4 659.25 1170.9 924.6

17 104.8 661.98 1188.8 892.9

18 114.9 664.71 1223.4 910.8

19 120.6 667.45 1251.4 945.4

20 123.7 670.18 1269.5 973.4

21 125.4 672.91 1280.7 991.5

22 126.4 675.64 1287.8 1002.7

23 127.0 678.37 1292.7 1009.8

24 127.5 681.11 1296.2 1014.7

25 127.8 683.84 1298.9 1018.2

26 128.1 686.57 1301.1 1020.9

27 128.4 689.30 1303.0 1023.1

28 128.6 692.04 1304.7 1025.0

29 128.8 694.77 1306.2 1026.7

30R 129.1 697.50 1028.2 278.0L 23.5465

33


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==============================================================================

UNIT 5, ’T-1’, ’MTBE COLUMN’ (CONT)

FEED AND PRODUCT STREAMS

TYPE STREAM PHASE FROM TO LIQUID FLOW RATES HEAT RATES

TRAY TRAY FRAC KG-MOL/HR M*KJ/HR

--------- ------------------------ ------------ -------- -------- ------------ ------------------------ ------------------------

FEED 5 MIXED 15 .9471 869.37 9.8626

PROD 6 LIQUID 1 575.94 3.4055

PROD 7 LIQUID 30 278.00 7.1853

OVERALL MOLE BALANCE, (FEEDS - PRODUCTS) 15.43

TOTAL HEAT OF REACTION AT STANDARD CONDITIONS -1.1572

TOTAL HEAT OF REACTION AT PROII ENTHALPY BASIS CONDITIONS -.7213

OVERALL HEAT BALANCE, (H(IN) - H(OUT) ) -6.6467E-06

SPECIFICATIONS

PARAMETER TRAY COMP SPECIFICATION SPECIFIED CALCULATED

TYPE NO NO TYPE VALUE VALUE

--------------------------------- -------- ------------ ------------------------- -------------------- --------------------

STRM 7 30 MOL RATE 2.780E+02 2.780E+02

UNIT T-1 1 RRATIO 1.100E+00 1.100E+00

REFLUX RATIOS

---------------- REFLUX RATIOS ----------------

MOLAR WEIGHT STD L VOL

----------------- ----------------- -----------------

REFLUX / FEED STREAM 5 .7287 .6318 .6974

REFLUX / LIQUID DISTILLATE 1.1000 1.1000 1.1000

34


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==============================================================================


MOLAR REACTION RATES KG-MOL/HR

COMPONENT TRAY 1 TRAY 2 TRAY 3 TRAY 4

-------------------- -------------------- -------------------- --------------------

1 NC4 .0000 .0000 .0000 .0000

2 IC4 .0000 .0000 .0000 .0000

3 1BUTENE .0000 .0000 .0000 .0000

4 BTC2 .0000 .0000 .0000 .0000

5 BTT2 .0000 .0000 .0000 .0000

6 IBTE .0000 .0000 .0000 .0000

7 MTBE .0000 .0000 .0000 .0000

8 MEOH .0000 .0000 .0000 .0000

9 TBA .0000 .0000 .0000 .0000

10 H2O .0000 .0000 .0000 .0000

11 DIB .0000 .0000 .0000 .0000

TEMPERATURE, DEG C 43.500 50.775 51.471 51.952

PRESSURE, KPA 621.000 621.000 623.732 626.464


-------------------- -------------------- -------------------- --------------------

1 NC4 .0000 .0000 .0000 .0000

2 IC4 .0000 .0000 .0000 .0000

3 1BUTENE .0000 .0000 .0000 .0000

4 BTC2 .0000 .0000 .0000 .0000

5 BTT2 .0000 .0000 .0000 .0000

6 IBTE .0000 .0000 .0000 -2.5733

7 MTBE .0000 .0000 .0000 2.5733

8 MEOH .0000 .0000 .0000 -2.5733

9 TBA .0000 .0000 .0000 .0000

10 H2O .0000 .0000 .0000 .0000

11 DIB .0000 .0000 .0000 .0000


PRESSURE, KPA 629.196 631.928 634.661 637.393

VOLUME, M3 5.000

35


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==============================================================================



-------------------- -------------------- -------------------- --------------------

1 NC4 .0000 .0000 .0000 .0000

2 IC4 .0000 .0000 .0000 .0000

3 1BUTENE .0000 .0000 .0000 .0000

4 BTC2 .0000 .0000 .0000 .0000

5 BTT2 .0000 .0000 .0000 .0000

6 IBTE -2.5327 -2.8062 -3.1954 -3.2871

7 MTBE 2.5327 2.8062 3.1954 3.2871

8 MEOH -2.5327 -2.8062 -3.1954 -3.2871

9 TBA .0000 .0000 .0000 .0000

10 H2O .0000 .0000 .0000 .0000

11 DIB .0000 .0000 .0000 .0000

TEMPERATURE, DEG C 54.763 56.481 59.417 63.760 PRESSURE, KPA 640.125 642.857 645.589 648.321

VOLUME, M3 5.000 5.000 5.000 5.000


-------------------- -------------------- -------------------- --------------------

1 NC4 .0000 .0000 .0000 .0000

2 IC4 .0000 .0000 .0000 .0000

3 1BUTENE .0000 .0000 .0000 .0000

4 BTC2 .0000 .0000 .0000 .0000

5 BTT2 .0000 .0000 .0000 .0000

6 IBTE -1.0336 .0000 .0000 .0000

7 MTBE 1.0336 .0000 .0000 .0000

8 MEOH -1.0336 .0000 .0000 .0000

9 TBA .0000 .0000 .0000 .0000

10 H2O .0000 .0000 .0000 .0000

11 DIB .0000 .0000 .0000 .0000


PRESSURE, KPA 651.053 653.785 656.518 659.250

VOLUME, M3 5.000


-------------------- -------------------- -------------------- --------------------

1 NC4 .0000 .0000 .0000 .0000

2 IC4 .0000 .0000 .0000 .0000

3 1BUTENE .0000 .0000 .0000 .0000

4 BTC2 .0000 .0000 .0000 .0000 5 BTT2 .0000 .0000 .0000 .0000

6 IBTE .0000 .0000 .0000 .0000

7 MTBE .0000 .0000 .0000 .0000

8 MEOH .0000 .0000 .0000 .0000

9 TBA .0000 .0000 .0000 .0000

10 H2O .0000 .0000 .0000 .0000

11 DIB .0000 .0000 .0000 .0000

36


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==============================================================================


TRAY 17 TRAY 18 TRAY 19 TRAY 20

-------------------- -------------------- -------------------- --------------------


PRESSURE, KPA 661.982 664.714 667.446 670.178


-------------------- -------------------- -------------------- --------------------

1 NC4 .0000 .0000 .0000 .0000

2 IC4 .0000 .0000 .0000 .0000

3 1BUTENE .0000 .0000 .0000 .0000

4 BTC2 .0000 .0000 .0000 .0000

5 BTT2 .0000 .0000 .0000 .0000

6 IBTE .0000 .0000 .0000 .0000

7 MTBE .0000 .0000 .0000 .0000 8 MEOH .0000 .0000 .0000 .0000

9 TBA .0000 .0000 .0000 .0000

10 H2O .0000 .0000 .0000 .0000

11 DIB .0000 .0000 .0000 .0000


PRESSURE, KPA 672.910 675.642 678.374 681.107


-------------------- -------------------- -------------------- --------------------

1 NC4 .0000 .0000 .0000 .0000

2 IC4 .0000 .0000 .0000 .0000

3 1BUTENE .0000 .0000 .0000 .0000

4 BTC2 .0000 .0000 .0000 .0000

5 BTT2 .0000 .0000 .0000 .0000

6 IBTE .0000 .0000 .0000 .0000

7 MTBE .0000 .0000 .0000 .0000

8 MEOH .0000 .0000 .0000 .0000

9 TBA .0000 .0000 .0000 .0000

10 H2O .0000 .0000 .0000 .0000

11 DIB .0000 .0000 .0000 .0000


PRESSURE, KPA 683.839 686.571 689.303 692.035

37


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==============================================================================


COMPONENT TRAY 29 TRAY 30

-------------------- --------------------

1 NC4 .0000 .0000

2 IC4 .0000 .0000

3 1BUTENE .0000 .0000

4 BTC2 .0000 .0000

5 BTT2 .0000 .0000

6 IBTE .0000 .0000

7 MTBE .0000 .0000

8 MEOH .0000 .0000

9 TBA .0000 .0000

10 H2O .0000 .0000

11 DIB .0000 .0000

TEMPERATURE, DEG C 128.841 129.067 PRESSURE, KPA 694.767 697.500

38


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42/47





==============================================================================

UNIT 15, ’T-3’, ’MEOH COLUMN’ (CONT)

ESTIMATED TRAY MECHANICAL DETAILS

SECTION TRAY ------------ DOWNCOMER WIDTHS, MM -------------------- NO VALVES

SIDE CENTER OFF-CTR OFF-SIDE OR CAPS

------------- -------- ------------- -------------------- ----------------- ----------------- -----------------

1 2 47.32 N/A N/A N/A N/A

1 3 44.31 N/A N/A N/A N/A

1 4 38.05 N/A N/A N/A N/A

1 5 30.39 N/A N/A N/A N/A

1 6 27.63 N/A N/A N/A N/A

1 7 27.19 N/A N/A N/A N/A

1 8 27.14 N/A N/A N/A N/A

1 9 27.15 N/A N/A N/A N/A

1 10 82.22 N/A N/A N/A N/A

1 11 82.15 N/A N/A N/A N/A 1 12 82.13 N/A N/A N/A N/A

1 13 82.12 N/A N/A N/A N/A

1 14 82.14 N/A N/A N/A N/A

1 15 82.17 N/A N/A N/A N/A

1 16 82.21 N/A N/A N/A N/A

1 17 82.25 N/A N/A N/A N/A

1 18 82.29 N/A N/A N/A N/A

1 19 82.34 N/A N/A N/A N/A

* NOTE THIS VALUE WAS NOT CALCULATED

40


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STREAM MOLAR COMPONENT RATES Mar95

==============================================================================

STREAM ID CW MKUP WOUT 1

NAME MKUP WATER MEOH FEED

PHASE LIQUID LIQUID LIQUID LIQUID

FLUID RATES, KG-MOL/HR

1 NC4 .0000 .0000 .0000 .0000

2 IC4 .0000 .0000 .0000 .0000

3 1BUTENE .0000 .0000 .0000 .0000

4 BTC2 .0000 .0000 .0000 .0000

5 BTT2 .0000 .0000 .0000 .0000

6 IBTE .0000 .0000 .0000 .0000

7 MTBE .0000 .0000 .00

mtbe.unlocked

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