Phosgene-free Route to Toluene Diisocyanate (1)

7/26/2019 Phosgene-free Route to Toluene Diisocyanate (1)

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University of Pennsylvania

ScholarlyCommons

Senior Design Reports (CBE)Department of Chemical & Biomolecular

Engineering

4-1-2010

PHOSGENEFREE ROUTE TO TOLUENEDIISOCYANATE

Nasri Bou-SabaUniversity of Pennsylvania

Caryl DizonUniversity of Pennsylvania

Devi KasihUniversity of Pennsylvania

Bryce StewartUniversity of Pennsylvania

is paper is posted at ScholarlyCommons.hp://repository.upenn.edu/cbe_sdr/16

For more information, please contact [email protected].
http://repository.upenn.edu/http://repository.upenn.edu/cbe_sdrhttp://repository.upenn.edu/cbehttp://repository.upenn.edu/cbehttp://repository.upenn.edu/cbe_sdr/16mailto:[email protected]:[email protected]://repository.upenn.edu/cbe_sdr/16http://repository.upenn.edu/cbehttp://repository.upenn.edu/cbehttp://repository.upenn.edu/cbe_sdrhttp://repository.upenn.edu/


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PHOSGENEFREE ROUTE TO TOLUENE DIISOCYANATE

Abstract

A Gulf Coast production plant was designed for a phosgene-free route manufacture of 2,4-toluene

diisocyanate (TDI) from toluene diamine (TDA). e process was designed to generate 300 million poundsof TDI per year within the required process specications. Two reactors were to be installed in order toimprove the overall yield of TDI, followed by a series of three distillation columns to ensure highly puremarket competitive product. Safety concerns, the start-up process, and other potential considerations are alsoincluded.

e results of economic analysis for the base case of the project returned a Net Present Value (NPV) of$20,653,700 with an initial rate of return (IRR) of 18.05% and a return on investment (ROI) of 12.03%.Further analysis on the assumptions made in these calculations may be required before nal project approvalis granted.

Disciplines

Biochemical and Biomolecular Engineering

is working paper is available at ScholarlyCommons:hp://repository.upenn.edu/cbe_sdr/16
http://repository.upenn.edu/cbe_sdr/16http://repository.upenn.edu/cbe_sdr/16


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PHOSGENEFREE

ROUTE

TO

TOLUENEDIISOCYANATENasriBouSaba(UniversityofPennsylvania)

CarylDizon(UniversityofPennsylvania)

DeviKasih(UniversityofPennsylvania)

BryceStewart(UniversityofPennsylvania)

SeniorDesignReport

April13,2010

UniversityofPennsylvania

DepartmentofChemicalandBiomolecularEngineering

FacultyAdvisor:Prof.LeonardFabiano,Dr.DaeyeonLee

Reccommendedby: Mr.BruceVrana,DuPontEngineeringTechnology


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PhosgeneFree Route to Toluene Diisocyanate BouSaba, Dizon, Kasih, Stewart

2

UniversityofPennsylvania

SchoolofEngineeringandAppliedScience

DepartmentofChemical&BiomolecularEngineering

220South33

rd

StreetPhiladelphia,PA19104

April13,2010

DearMr.Fabiano,Dr.Lee,andMr.Vrana,

Enclosed is our proposed process design on PhosgeneFree Route to Toluene

Diisocyanate (TDI) problem statement provided by Mr. Bruce Vrana of DuPont Engineering

Technology. Our focus is to design a high yielding process that is both technologically and

economicallyfeasibleinproducing99.95%pureTDIfromtoluenediamine(TDA).Theprocessis

made up of two main process blocks the Reactor System and Separation Process and

achieves the required capacity specified in the problem statement. Included in our

consideration is todesignanoptimalprocessby recycling reactants,minimizingutility costs,

andremovingbyproductsinanecofriendlymanner.

The following report details the process, equipment needs and estimated costs,

approximatedpowerrequirements,andadetailedeconomicanalysis.AcompleteASPENPlus

flow sheet is also enclosed for your reference. Due to limited data availability, assumptions

relevant to theprocess designarealsodiscussedand variousnon and economic sensitivity

analyseshavealsobeenincluded.

Finally,wewouldliketothankProfessorLeonardFabiano,Dr.DaeyeonLee,Mr.Bruce

Vrana,Mr.SteveTieri,andMr.GarySawyerforthegreatassistance.Kindlycontactthedesign

groupifyouhaveanyquestionsregardinganyaspectofthereport.

Sincerely,

_________________________ __________________________

NasriBouSaba DeviKasih

_________________________ __________________________

CarylDizon BryceStewart


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TableofContents

Abstract.....6

Introduction....7

ProjectCharter...12

InnovationMapandTechnologyDevelopmentSummary..14

MarketandCompetitiveAnalyses...18

PreliminaryProcessSynthesis.......23

ProcessFlowDiagramsandMaterialBalances...32

ProcessDescriptions.....41

EnergyBalanceandUtilityRequirements.....50

ProcessEnergyBalance......51

UtilityRequirements.......57

CoolingWater..........57

Steam.........58

FuelOilandSolidWaste...59

Electricity.......59

UnitDescriptions.....60

UnitSpecificationSheets......75

EquipmentCostSummary...125

FixedCapitalInvestmentSummary..128

OperatingCostandEconomicAnalysis.....132

EconomicAssumptionsandProjectOperations.....133

OperatingCostSummary.......134

VariableCosts......134

FixedCosts.......137

CashFlowandProfitabilityAnalysis..........139

OtherEconomicsUncertainties.....145

OtherIssuesandConsiderations...147

EnvironmentalConcerns...148

PlantSafetyConcerns....149

PlantStartup....152

ConclusionandRecommendations..153


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Acknowledgements.......157

ListofFiguresandTables..........159

Bibliography........162

Appendix.......167

Appendix1......168

Appendix2......187

Appendix3......189

Appendix4......191

Appendix5......193

Appendix6......196

Appendix7......216

Appendix

8......231

Appendix9......351


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Abstract


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6

Abstract

AGulfCoastproductionplantwasdesignedforaphosgenefreeroutemanufactureof

2,4toluene diisocyanate (TDI) from toluene diamine (TDA). The process was designed to

generate300millionpoundsofTDIperyearwithin the requiredprocess specifications.Two

reactorsweretobeinstalledinordertoimprovetheoverallyieldofTDI,followedbyaseriesof

threedistillationcolumnstoensurehighlypuremarketcompetitiveproduct.Safetyconcerns,

thestartupprocess,andotherpotentialconsiderationsarealsoincluded.

TheresultsofeconomicanalysisforthebasecaseoftheprojectreturnedaNetPresent

Value (NPV) of $20,653,700 with an initial rate of return (IRR) of 18.05% and a return on

investment (ROI)of12.03%. Furtheranalysison theassumptionsmade in these calculations

mayberequiredbeforefinalprojectapprovalisgranted.


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7

Introduction


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Introduction

TDI are intermediates in the production of polyurethanes and polycarbonates, which

havemanyusefulproperties.Polycarbonatesarewidelyused in themanufactureofCDand

DVD discs, while polyurethanes are used in the production of foams, elastomers, and hard

polymers. WiththeinputofProfessorFabiano,whohadampleexperienceinTDIprocesses,we

wereurgedtocreateaprocesstoproduceTDIwithalmost100%purity.

Thefollowingreportdescribesachemicalprocessforproducingvirtually100%pureTDI

without introducing thewidelyused component,phosgene. Phosgene isa colorless volatile

liquidorgasthatisproducedbypassingpurifiedcarbonmonoxideandchlorinegasthrougha

bedofporousactivatedcarbon. Itisavaluableindustrialreagentandbuildingblockinorganic

synthesisbut isalsoahighly toxicmaterial. Its leakshave caused several casualties inmany

industrialprocesses.

Phosgene was formerly used as a chemical weapon during World War I. At room

temperature(70F),phosgeneisapoisonousgas.Itsgasmayappearcolorlessorasawhiteto

paleyellowcloudand itsodormaynotbenoticedbyallpeopleexposed.Althoughphosgene

wasneverasnotoriousasmustardgas,itisaninsidiouspoisonthathaskilledfarmorepeople.

AmongthechemicalsusedinWorldWarI,phosgenewasresponsibleforthelargemajorityof

deaths,about85%ofthe100,000deathscausedbychemicalweapons. Itssymptomsmaybe


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slow tobe recognized,asphosgenecanonlybedetectedat0.4ppm,which is four times its

safetyThresholdLimitValue.1

Phosgene

reacts

violently

and

decomposes

to

toxic

compounds

on

contact

with

moisture, including chlorine, carbon monoxide and carbon tetrachloride. People may be

exposed tophosgene through skinoreye contact, touchingordrinkingwater,breathingair,

and eating contaminated food. Inhalation can cause fatal respiratory damage as phosgene

reactsheavilywithHClthatisreleasedinitsreactionwithwaterinthelungs.Itcanalsocause

damage to the skin,eyes,nose, throat,and lungs.Today,gaseousphosgenehas increasingly

beensupplantedbymoreeasilyhandledreagents.This iswhy itwasextremely importantto

removePhosgeneasareactantinourTDIproductionprocess.1

Wewerechargedwithcreatinganeconomically feasibleandenvironmentally friendly

process design for producing 300 million pounds of TDI per year in high yield from toluene

diamine (TDA). It was our goal to create a design that recycled the majority of unreacted

startingmaterialsas well asdisposed any wastematerial in aneconomical and ecofriendly

manner. Wewerealsotominimizetheplantsutilityrequirementsinanefforttoincreaseits

sustainability.

The phosgenefree pathway of producing TDI by reacting TDA, oxygen, and carbon

monoxide in the solvent, 2,2,2trifluoroethanol (TFE), was introduced to us as an attractive

alternativetothecommonmethodsofproducingTDI.

1Hazards:Phosgene.CentersforDiseaseControlandPrevention,Sept.2005.Web.28Jan.2010.


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Theoverallreactionis:

+ 2C=O + O=O +

Arepresentationofthismechanismispresentedbelow:

(1)

(2)

With further researchwe concluded thatourprocessmost likely includesa twostep

mechanism. Inthefirststep,TDAreactswithcarbonmonoxide,oxygen,andthesolvent,TFE,

to produce the intermediate toluene dicarbamate. In the second step, the dicarbamate is

Catalyst

Catalyst

O

H H

NH2

NH2

NCO

NCO

NCO

NCO

+ +

2

2 2

NH

O

O

O

NH

O


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degradedtocreatetheTDIproductandthewaterbyproduct. TheTFEsolventisregeneratedin

thisstepaswell. Itisimportanttonotethattheentirereactionmechanismiscarriedoutinthe

presenceofN,N(bis(3,5ditertbutylsalicylidene)ethylenediamino)cobalt(II)[Co tBu Salen]

catalyst.2

2Hassan,Abbas,EbrahimBagherzadeh, RayfordG.Anthony,GregoryBorsinger,andAzizHassan.SYSTEMAND

PROCESSFORPRODUCTIONOFTOLUENEDIISOCYANATE


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ProjectCharter


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ProjectCharter

ProjectName PhosgeneFreeRoutetoTolueneDiisocyanate

ProjectChampions NasriBouSaba,CarylDizon,DeviKasih,andBryceStewart

ProjectLeaders BruceVrana,Dr.DaeyonLee,andMr.LeonardFabiano

SpecificGoals ToproducehighpurityTDIfromTDAinhighyieldusinganenvironmentallyfriendlyphosgenefreeprocess

ProjectScope Included:o Productionof300millionpoundsofhighlypure

TDIfromTDAwithoutusingPhosgene

o Creationofanenvironmentallyfriendlyprocess

withhighamountsofrecycleandminimizeduse

ofutilities

o Maintaininganeconomicallyfeasibleprocess

withanacceptableprofitmargin

Excluded:

o Separationofthe2,4TDIfrom2,6TDI(80%and

20%compositionrespectively)

Deliverables ProcessEfficiencyAnalysiso ProductPurity

o ProductYield

o UtilityUsage

o SafetyData

EconomicDatatoManagement

o CostAnalysis

o Profits

o ROI

ProjectTimeline ToproducemarketreadyTDIin12months


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InnovationMapand

Technology

Development

Summary


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InnovationMap

Figure1:InnovationmapofcommercialTDIproduction


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TechnologyDevelopmentSummary

The traditional route for the manufacture of TDI starts with the nitration of toluene

using nitric acid to produce dinitrotoluene followed by catalytic hydrogenation to toluene

diamine.The toluenediamine isdissolved inan inert solventand reactedwithphosgene to

produce a crude TDI solution. Phosgene is made onsite in a simple, single step process by

passing purified carbon monoxide and chlorine gas through a bed of highly porous carbon,

whichactsasacatalyst.Thesubsequentseparationandpurificationoftheproductsofreaction

fromthepolymericbyproductsthatareformedisamultistepprocess.Thehydrogenchloride

that isproducedasabyproductofthereaction isrecoveredandsoldeitherdirectlyor inthe

form of hydrochloric acid (HCl). On the flip side, HCl, which is produced in stoichiometric

amount as a byproduct, causes corrosion, and thus a stoichiometric amount of NaOH is

requiredtoneutralizetheHCl.(SerranoFernandezetal,2008)3

Eventhoughthistechnologyhasbeenthebasisofcommercialisocyanateproductionfor

many years, numerous attempts have been made to develop even lower cost, non

phosgenationprocessestoproduce isocyanates.Furthermore,asrestrictionsupontheuseof

very toxic materials such as phosgene within the chemical industry have become more

rigorouslyenforced, therehasbeen increasing interest indevelopingalternativemethods to

phosgeneinthesynthesisofisocyanate.

Bayerhas

developed

agas

phase

phosgenation

(GPP)

process

for

the

production

of

TDI

from TDA. The main difference from conventional TDI processes is in the use of gasphase

3SerranoFernandez,FranciscoLuis,BeatrizAlmenaMunoz,AnaPadillaPolo,AranaOrejonAlvarez,CarmenClaver

Cabrero,SergioCastillonMiranda,PilarSalagreCarnero,andAliAghmiz.OnestepCatalyticProcessforthe

SynthesisofIsocyanates.REPSOLYPF,S.A.,assignee.Patent7423171.9Sept.2008.


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reactionofTDAandphosgene,asopposedtothesereactantsbeinghandledasdilutesolutions

inasolventsuchasorthodichlorobenzene.Thegasphasephosgenationtechnologyresults in

significantsavingsonsolvents, leadingtooperatingcostsavingsduetoareduction inenergy

consumption required to process the much smaller volume of solvent during distillative

recovery.Themuch shorter residence timeofTDAandphosgene in the reactor reduces the

required phosgene process inventory considerably. Further benefits are significantly greater

reactor throughput per unit time (spacetime yield) and the ability to downsize key plant

components.Thesesizereductions, leadtoadditional investmentcostsavings.Thegasphase

technologyalsoprovidesimprovedreactionselectivity,generatingfewerbyproducts.Thisroute

avoidstheuseofphosgeneandwasterecoveryproblemsassociatedwithHCl.Processsafetyis

vastlyimprovedbythereductioninbothphosgeneandsolventinventorieswithintheprocess.

A furthersafetyenhancement istheabilitytostartupandshutdownthegasphaseprocess

quickly.

Themost recentattempt is theEniChemUrethanePyrolysis (NonPhosgene)Process:

Here,oxidativecarbonylationofmethanolisusedtoproducedimethylcarbonate(DMC).DMC

is then reacted with TDA to give a urethane intermediate which is then cracked at high

temperatureandlowpressuretogiveTDI.(Nexant,2008)4

ExistingprocessesandproductionfacilitiesforproducingtheTDImixture,inparticular,

aresubject

to

various

constraints

such

as

mass

flow

limitations,

product

yield,

plant

size

and

energyconsumption.Accordingly,thereiscontinuinginterestinimprovingthewaythatTDIis

produced.

4DevelopmentsinTolueneDiisocyanate(TDI)ProcessTechnology.Rep.Nexant,Inc.,Oct.2008


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MarketandCompetitive

Analyses


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Marketand

Competitive

Analyses

TDI is often marketed as 80/20 and 65/35 mixtures of the 2,4 and 2,6 isomers

respectively.Asoneofthehighlyproduceddiisocyanates,TDIaccountsfor34.1%oftheglobal

isocyanate market in 2000 (ICIS, 2010)5. The main outlet for TDI is in the manufacture of

polyurethane(PU)flexiblefoamsusedinfurniture,bedding,andautomotiveandairlineseats.

This is achieved by the reaction of TDI with a polyol to produce the foam. Meanwhile,

polycarbonatesareparticularlyvalued for theiropticalclarityand impact resistance,andare

usedinCDandDVDdiscsamongmanyotherapplications.

Globally, flexible PU foams constitute by far the largest market for TDI, 88% of the

global demand (30% for transportation, 20% for furniture, 14% for carpet underlay, 11%

bedding, 5% packaging, and 8% for other foam uses). Rigid urethane foams come next,

contributingto4%ofthedemand,followedbyPUadhesivesandsealantswith3%,PUcoatings

andPUelastomersforanother3%and2%respectively(ICIS,2010).5

Polyurethanecoatingsareoneofthefastestgrowingsectorsofthepaintsandcoatings

industry.Despite their relativelyhighcost, theyaresuitable fora rangeofhighperformance

applications due to their excellent durability, resistance to corrosion and abrasion, and

flexibility. Markets for PU coatings include automotive refinishing, wood finishes and high

performance anticorrosion coatings. On the other hand, PU elastomers are noted for their

toughness,flexibility,strength,abrasionresistance,shockabsorbencyandchemicalresistance.

5"TolueneDiisocyanate(TDI)CASNo:584849."ICIS.com.


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Because they are relativelyexpensive compared tomostotherelastomers, theyareused in

moredemandingapplicationssuchasautomobilebumpercoversandfacias, industrialrollers,

sportsolesandboots,andmechanicalgoods.

Today, thenumberofglobalTDIenterprises isover30withmore than40setsofTDI

productionlines,thetotalproductioncapacityis2.1milliontonsperyearandmainlylocatedin

Asia, Europe and theUnited States. With most of TDIs output going into the furniture and

automotive sectors,demand is sensitive toeconomicactivity.With theeconomicdownturn,

flexiblePU foamsdemandhas fallen in2009bybetween5%and20% intheUSandwestern

Europe,accordingtoUSbasedconsultantsSRI. Instrongereconomies,thefallhasbeenmore

limitedupto5%.However,SRIexpectsdemandforflexiblefoamswillreturntogrowat2.4%

peryearthrough2011and24%peryearupto2013.

Currently, there are five major producers of TDI serving the global demand, namely

BASF,Bayer, Lyondell,MitsuiChemicals,andDowChemicals.The currentUSTDIproduction

levelsexpressedintermsofcapacitydataforseveralproducersaretabulatedbelow.

Company Capacity(MMlbsperyear)

BASF 350

Bayer 400

Dow 220

Total 970

Figure2:

Major

producers

TDI

production

capacity

5

Thedemand forTDI is stillon the increase today.Regionally,Asia contributes to the

fastestgrowthataround8%peryear. ThisismainlyduetoaboominChinasautomobileand

constructionsectors,whichaccountsforthreequartersofTDIconsumption.Automotivesales


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inChinapassed the10millionvehiclesperyear level in2009with salesupby38% in2009

compared to the previous year, according to the China Association of Automobile

Manufacturers.Moreover,variousproducersinChinaarealsoexpandingtheircapacity.Bayer

MaterialScience is constructing a 250,000 metric tons TDI plant in Shanghai, while Gansu

Yinguang Chemical Industry Group Co., Ltd. and Hebei Cangzhou Dahua Co., Ltd. also have

expansion plans that are scheduled to come on stream in 2010. If these projects can be

completedonschedule,thedemandforTDIinChinaisexpectedtobearound700,000tonsin

2010.6

Growth intheUS itself ismuch lowerthantheworldaverageandhasbeenadversely

impactedbytheslowdownintheeconomy.FlexiblePUfoamsaccountfor88%ofTDIdemand

in theUSwith transportation, furniture,carpetandbeddingmarketsbeing themainoutlets.

The ailing US transportation industry accounts for nearly 22% of total PU consumption,

accordingtotheAmericanChemistryCouncil.Thedemand,imports,andexportsgraphforTDI

intheUSisprovidedinthegraphbelow:

6AnalysisandForecastofChinaTDIMarket20092010.ReportLinker.Web.15Mar.2010.


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Figure3:TDIdemandinUSAshowsamoderateincreasingtrendabove7

Even

with

the

overall

recent

decreasing

demand

trend,

the

TDI

installed

capacity

is

barelysufficienttomeetcurrentUSdomesticdemandandexportvolumes.Neartermdemand

increases will have to be addressed by an increase in imported material or decreasing the

amountexported.Asthereisnoapparentreliefinsightforenergyandfeedstockcostpressure,

pricing will likely remain at the current historical high level of US$1.901.96 per pound,

accordingto ICIS.Thus,pricing theTDI toUS$1.50perpoundas inourprojectwill lookvery

promising,especially supportedby theacceleratedgrowth inautomotiveand transportation

industries.

7DevelopmentsinTolueneDiisocyanate(TDI)ProcessTechnology.Rep.Nexant,Inc.,Oct.2008


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PreliminaryProcess

Synthesis


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Preliminaryprocess

synthesis

Rawmaterialsandproductspecifications

Thephosgenefreeroutemanufactureof300millionpoundsofTDIperyear isanovel

processsuchthat informationregardingthekinetics,theeffectivenessandtheroleofvarious

typesofcatalyst,solvent,andpromoterareverylimited.Therefore,theTDIsynthesisislargely

basedon theUSpatent inventedbyFernandezetal,2007.For thisprocess,a reactant feed

consistingofTDA,oxygenandcarbonmonoxideispassedoverafixedbedofSchiffBaseType

LigandCatalyst,CotBuSalen.Anorganicsolvent,2,2,2trifluoroethanol(TFE)andapromoter,

sodiumiodide(NaI),arealsochargedthroughoutthereactionprocesstoensuretheTDIoverall

yieldof64%isachieved,asspecifiedinthepatent.

The amount required for each of the raw materials and the process enhancers are

derivedfromthelaboratoryscaleratiowithseveralamendmentsforoptimizationmodeledby

Aspen.Therequiredratiosoftherawmaterialsaretabulatedbelow.

Table1:TherequiredratioofrawmaterialsperpoundofTDIproduced.

RawMaterial: Unit: Required

Ratio:

Toluenediamine lb 0.73 lbperlbofTolueneDiisocyanate

Carbonmonoxide lb 3.07 lbperlbofTolueneDiisocyanate

Oxygen lb 0.18 lbperlbofTolueneDiisocyanate

TherequiredamountofTFEandNaIarefixedfortheentireprocesssincetheyarenot

consumed.AsmodeledbyASPEN,therespectiveamountofTFEandNaIneededare1,115,835

poundsand2,730poundsforatotalof314millionpoundsofTDIperyear.The5%excessofTDI


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production works as a buffer considering possible polymeric formation throughout the

synthesis. In addition, the ratio of the carbon monoxide to oxygen in the vapor phase is

controlledto49:1toavoidexplosionrisk.

To improvetheoverallyieldofTDIproductionand inturnreducetheproductioncost,

twomajorreactorsystemoptionsareproposed.

Option1:

A single3looppass reactor isassembled to improve theoverallTDIproductionyield

from64%(Fernandez,etal)to97.2%(Aspen).Theimprovedyieldisexpectedtobemaintained

astheoperationreachessteadystate.Theprocessflowsheetforthisscenarioispresentedin

Figure4.

Option2:

Two reactorsareassembled such that thevaporproductof the first reactor ismixed

withtherecyclestreamcomingfromtheseparationsystem.ThefocusistouseupasmuchTDA

andany intermediateproductsobtained from the first reactor. Thisprocess ispresented in

Figure5.


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Figure4:Option1 Singlethreelooppassreactordetailedprocessflowsheet


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Figure5:Option2 Tworeactorsystemdetailedprocessflowsheet


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Thechoiceofthereactorsystemismadebasedontwomainconsiderations:

1. PossiblecostsavingsofTFE

BasedonthediscussionwithShaunJulian,anAccountManagerinoils,greases,

waxesandchemicalsdepartmentatHalocarbonProductsCorporation, it is foundthat

the required amount of TFE in this project accounts for approximately 25% of the

currentTFEglobaldemandof5millionpounds. Inaddition, thecurrentcostofTFE is

approximately $12 per kilogram or $5.45 per pound. Thus, the TDI manufacture is

enormouslysensitivetoTFErequirement.

ComparingtheamountofTFEofwhichthetwooptionswillconsumeusingthe

ASPEN flow sheet, option 1 will save 22,000 millions of TFE, which is equivalent to

$120,008.

2. Reactorsize

The reactor system inoption1 isa considerablymorecomplexassembly than

thatinoption2whichonlyconsistsoftwoindividualpackedbedreactors.Thefollowing

isthefigureofreactorsystemconfigurationinoption1.


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Figure6:Threelooppassreactorsystem

AsshowninFigure6thereactorsysteminoption1consistsofaholdingvessel,a

packed bed reactor, a cooler, and a pump. In addition, there is a big tradeoff in

loweringthereactorsresidencetimesincethevolumerequiredisinverselyrelated.Size

optimization by changing the volumetric flow rate passing through the reactor also

involvesalargeuncertaintyintheeffectivenessoftheactualreactionstakeplace.Thisis

due to the unavailability of the reaction kinetics data. Furthermore, the net work

requiredbythepumpwillbeconsiderablyincreasedandthusincreasingtheelectricity

consumption.

Fixed bed reactor

Cooler

Pump

Holdingvessel


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Assuming a base case of per pass residence time of 20 minutes of halffull

reactor8,a3looppassreactorwillcost$55,109,461,withavesseldiameterandlength

of135ftand67ftrespectively.Ontheotherhand,thereactorsysteminoption2costs

$19,041,059.23with thesecond reactoronlyonethirdof thesizeof the firstreactor.

Finally, there is no internal utility requirement involved. Appendix 1H contains the

detailedcalculationsonthereactorcosting.

Thesummaryoftheincrementalpossiblesavingofoption2istabulated.

Table2:Summaryofincrementalcostsavingofreactorsysteminoption2

TFE

saving

Reactor

price

saving

Utility

requirement

Total

saving

Option2 ($120,008.15) $36,068,401.73 None $35,948,393.58

Considering the profitability of the two potential designs described, option 2 is

significantlybeneficialfrombusinessperspective.Furthermore, installingtwosmallerreactors

aremorefeasiblethanbuildingoneconsiderablybiggerreactor.

Separationprocessandheatintegration

FollowingtheproductionofTDI,itiscrucialtoisolatetheproductaspureaspossibleto

be accepted in the market. The competitive minimum purity requirement in the market is

99.5%. (ICIS) To achieve successful separation, 3 distillation columns are proposed. The

separationtrainswiththedetailsofisolatedcomponentsarepresentedinFigure7.

8The US patent OneStep Catalytic Process for the Synthesis of Isocyanates describes areaction time ranges from 3 minutes to 3 hours. Due to the lack of relevant reactionkinetics data, the reaction time base case assumption is one hour.


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Figure7:Distillationseparationcomplex

Finally,tominimizetheutilityrequirementandcost,andthusincreaseprofitability,heat

integrationprocesswouldalsobeconductedthoroughly.

TFE, TDI, H20, O2,CO

H2O

TDATDCARB

NaI

TDI, H2O

TDI

O2, CO, TFE

2

3

1

Product mix


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ProcessFlowDiagramand

MaterialBalances


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ProcessBlockDiagrams:

Recycle

Figure8:

Process

Block

Diagram

Section2:

Separations

Section1:

Reactors

D101TOPTORECYCLE

D101TOPTOR102

R100LIQUIDTOSEPARATIONS

D100BOTTOMSTOR102

TDA

O2

CO

TFE

O2MAKEUP


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Figure9: ProcessFlowDiagram

Figure10: Reactorsystemsection


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TemperatureF 36.51 36.51 74.96 140.00 140.00 101.75

Pressurepsia 653.00 653.00 653.00 648.00 2.01 6.00

VaporFrac 0.00 0.00 0.00 0.00 0.00 0.00

MoleFlowlbmol/hr 9504.23 2661.18 2750.53 0.90 227.98 456.91

MassFlowlb/hr 930507.88 260542.21 283360.47 230.49 39662.81 8273.58

MassFlowlb/hr

TDA 0.00 0.00 5146.06 51.98 1.03 0.00

O2 129.93 36.38 36.38 0.00 0.00 0.00

CO 7786.08 2180.10 2180.10 0.00 0.00 0.00TDI 0.00 0.00 0.70 0.01 39656.97 47.18

WATER 0.16 0.05 0.05 0.00 4.81 8226.39

TDCARB 0.00 0.00 17671.51 178.50 0.00 0.00

SOLVENT 922591.71 258325.68 258325.68 0.00 0.00 0.01


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45

ProcessDescription


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46

ProcessDescription

BlockFlowDiagram

Figure12.BlockflowdiagramfortheTDIproduction

OverallProcessDescription

The block flow diagram given by Figure 12 illustrates the flows to and from the key

sections of the phosgenefree TDI production process. The conversion from TDA to TDI is

accomplished through a twostep catalytic reaction carried out between 120C and 180C

(248F356F)and5100bar(72.5psia 1450psia).Therearetworeactors intheprocess,

whichworktomaximizehourlyyield.Thereactors inthisprocessareallowedtooperatenon

adiabatically with the feeds entering into the reactor at 120C (248F), the bottom of the

optimaltemperaturerange,andthereisatemperatureincreaseto139.3C(282.8F)inthefirst

reactorandatemperatureincreaseto137.5C(279.5F)inthesecondreactor.Thefirststepin

Decompositionof

intermediatesto

TDI

TDARecycle

CarbamatesRecycle

TDI

TDA

O2

Catalytic

oxycarbonylation

(Formationof

carbamate

intermediates)

Separation

process

CO


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48


51/399


FlowSheetDiagram

Figure13DetailedASPENPlusflowsheetofTDIproduction


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50

DetailedProcessDescription

Figure13isamorecomprehensiveprocessflowsheetthatgivesadetailedviewofthe

equipmentandflowstreamsinvolvedintheTDIproductionprocess.Thereareeffectivelytwo

majorsectionsoftheprocessthereactionsectionandtheseparationsection.Throughoutthe

reaction section, all the streams and equipment are maintained at a high pressure,

approximately653psia (45bar).Theseparationprocesssection ismaintainedat lowpressure,

with a slight pressure drop gradient over the threecolumn distillation chain from 12psia to

9psia(0.83to0.62bar).Thestreamconnectingthereactionsectiontotheseparationsectionis

decompressedby

avalve,

and

the

streams

that

gets

recycled

back

from

the

separation

section

tothereactionsectioniscompressedbyapump. Thevalvesafelyseparatesthehighpressure

halfoftheprocess fromthe lowpressurehalfand itactsasasafeguardtomakesurethat if

somethinggoeswronginthehighpressurehalfitcanbeisolatedfromthelowpressurehalf. In

addition this allows all of the high pressure piping to be separated from the low pressure

piping.

TheflowsheetinFigure13showsanopenloopsystem,butismeanttomodelaclosed

loopsystem. Therearetworecyclestreamsleavingthesecondreactorsystemwhich,inreality

wouldcombinetoformthetotalrecycletothefirstreactor. Thesestreamsareseparatedinto

vapor (PSEUDVAP) and liquid (PSEUDLIQ). These streams consist of the combination of the

exits from the second reactor system and any reactant materials recovered from the

separationsprocessesandnotfedintothesecondreactor. Thoughitisnotexplicitlyillustrated

inthe flowsheet,PSEUDOVAP ismixedwiththeO2andCOstreamsandthenbubbled intoR

100. PSEUDOLIQwillbemixedwiththeTDAandSOLVENTstreamsbeforeenteringR100asa


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52

mixedwithapartofthecompressedsolventrecyclestream(S119),whichis28.0%ofthetotal

solventrecyclestream. Thiscombinedstream(S121)isheatedto248FandfedtoR102.The

othersplitfromstreamS118calledS126 iscombinedwithtwootherreactorstreamstobe

recycledtoR100asPSEUDLIQ. Thegivensplitfractionsoftherecyclestreamswerecalculated

basedontheamountofTFEneededtodissolvetheO2andCOinthevaporeffluentandonthe

cost and yieldoptimal reactor size of the second reactor. The second reactor is also

maintainedat 45 bar and increases to a temperature of 279.5F. Both the liquid and vapor

effluent streams (S124 and S125) from R102 are mixed with the recycle streams from

separationsthataresubsequentlyfedR100inthefollowingmanner.S125ismixedwithpart

oftheR100 liquideffluent(S126)andeventuallyfedbacktoR100asPSEUDLIQ. PSEUDLIQ

willbemixedwiththeTDAandSOLVENTfeedliquidsandfedintothereactorasasingleliquid

feed. S124 is mixed with part of the R100 vapor effluent, S127, and refed to R100 as

PSEUDVAP. PSEUDVAPwillbemixedwiththeO2andCOgas feedspriortobeing fed tothe

reactor

as

a

single

vapor

feed

which

will

be

bubbled

into

the

system.

Both reactors have an effective product yield of 64% (82% conversion from TDA to

carbamates, 78% conversion from carbamates to TDI). This particular reactor system design

waschosenover thenumberofconsideredalternativesbecause it is themostcosteffective

withregardtoyieldandequipmentcost.Thestreamsfedintothefirstreactoraretabulatedfor

referenceinTable3.CO,O2,TDAandSOLVENTaresuppliedasfreshfeedsormakeupstreams

basedonconsumptionorlossofthereactantselsewhereintheprocess.

Withtheexceptionofthevaporphase inthetworeactors,alloftheCOandO2 inthe

systemmustbedissolved intotheTFE,because inthegasphase it isnecessarytomaintaina


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53

19:1ratioofCOtoO2toremainoutsideoftheexplosionriskrange.Inordertomaintainsafe

gaseousconcentrations,thereactorsareinitiallychargedwithaCOandO2mixturesignificantly

greaterthantheprescribed19:1ratio.Duringregularoperation,COandO2arebubbled into

thereactorsolutionatonlyalittleovera2:1ratio(2.39:1),therespectivestoichiometricratio

for the reaction.Because the gasesareaddedjustatorbelow their saturationpoint in the

solvent,theinitialcompositionofthegasphaseinthereactordoesnotdecreasesignificantly.

However, as a preventative measure, it is still necessary to include a control feedback

mechanismthatmonitorsthecomponentconcentrationsinthevaporphaseofthereactorand

controlstheCOandO2feedratesinresponse.

SeparationProcess

Wewillberunningasomewhattraditionalseparationsprocessbyusingdistillationto

separateourfinalproduct,TDI,fromthebyproductsandanyleftoverreactants. Toaccomplish

thedesiredseparations,theprocessrequired3distillationcolumns. Theonlystreamentering

theseparationsfromthereactorssectionisthebottomsliquidfromthefirstreactor.

The stream connecting the reaction to the separation section, S104, must be

decompressedfrom45barto0.345bar(653psiato5psia),sinceallthreedistillationcolumnsare

operatingatvery lowpressures.D100separatestheTDA,carbamates,NaIandsludgeoutas

theheavycomponentsinthebottomsproduct(S106)atarateof90.2lbmol/hr.Thisstreamis

thenrecompressedto653psiaandasidestream istakenouttoremovesludgebeforebeing

recycledbacktothereactionsection.Theflowsheetshowsasplitterwithanoutgoingsludge

streamatasplit fractionof1%tomodeltheestimatedsludge removalnecessary toprevent


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54

buildup.Asmentionedearlier,itisnecessaryforD100tobecoatedinHastelloyC276because

of the volume of NaI that will be flowing through it. The distillate (S109) from D100 is

compressedfrom2psiato12psiaandheatedfrom35Fto120FbeforeenteringD101forthe

next separation step.TheD101distillate (S117) containsalmostall (99.99%)of the solvent

thatenterstheseparationsystem.Thisstreamiscompressedandrecycledbacktothereaction

system.Thebottoms(S112)arefedstraight intothethirddistillationcolumn,D102.S112is

almostpurelyTDIandwastewater.Wastewatercomesoutasdistillate(WASTEWTR)atabout

99.4% purity, with a negligible amount of TDI and trace amounts of TDA and solvent. This

wastewater stream will be stored and shipped to a treatment center to be disposed of as

outlinedinEPAregulationsdiscussedintheOtherConsiderationssectionofthisreport. The

bottomsproductofD102is99.9%pureTDIat352.2Fand2.01psia.Thisfinalproductiscooled

to140Fandsenttostorage.

Afinalnoteregardingtheseparationsofourprocessisablackboxdesign,notpictured

inthefigure,whichwillcontainawhitefilmevaporator. Thewhitefilmevaporatorwillbeused

todisposeoftheheavypolymericsludgematerialproducedinthefirstdistillationcolumnasa

resultofprocessingTDIatsuchhightemperatures. Weassumeda lossofabout46%ofour

productduetothispolymericsludgewaste. Inresponse,webuilt ina5%overproductionof

TDItoaccountforthisunavoidableloss.


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55

EnergyBalanceandUtility

Requirements


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56

EnergyBalance

Oneofthemajorconcernsinthisprocesswastheamountofheatingandcoolingwhich

isneeded,primarilyinthethreedistillationcolumns. Whileitisknownthatdistillationisboth

energyintensiveandanenergeticallyinefficientprocess,itwasstilldeemedthebestseparation

methodtoisolatethepureTDI.

Oneareawhereenergywasmanaged tobe savedwasbyoperating the two reactors

nonadiabatically. Each reactor system was modeled in aspen, and the nonadiabatic

temperature risewas found for theentering compositionofeach reactor. According to the

patent, the reactionwilloccurbetween212Fand392F,and ithasanoptimal temperature

rangebetween248Fand356F. Becausetheeffectofoperatinginanonoptimaltemperature

rangeisunknown,thefeedstreamstothereactorwerekeptat248F,andtheexittemperature

afteranonadiabaticreactionwasfoundtobe282.7Fforthefirstreactorand279.5Fforthe

secondreactor. Sincebothofthesetemperatureswerestillintheoptimaltemperaturerange

forthereaction,itwaschosentooperatethereactorsnonadiabaticallyandnotspendenergy

tomaintainaconstanttemperature inthereactor. Thefirstreactorwouldhaverequiredthe

removalofover44MBtuperhourtomaintainitat248F,andthesecondreactorwouldhave

requiredtheremovalofover8.8MBtuperhourtomaintain itat248F. Thisdecisionsaved

roughly$150,000incoolingwater.


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57

Asseen inTable6,therewerestill5streamsthatneededtobeheatedand3streams

thatneededtobecooled. Table7showsthateachofthethreedistillationcolumnshadbotha

condenseranda reboiler that require largeamountsofenergy. StreamS121 requires20.6

MBtuperhourtoheatthestreamfrom75Fto248Ftopreheatthe liquidstreamgoing into

thesecondreactor.StreamS110requires173.4MBtuperhrtoheatthestreamfrom35Fto

120 F to preheat the liquid stream entering the second distillation column. Stream S129

requires 78.5 MBtu per hour toheat the stream from119 F to 248 F topreheat the liquid

recyclestream. StreamS131requires1.0MBtuperhourtoheatthestreamfrom106Fto248

Ftopreheatthevaporstreamenteringthesecondreactor.StreamS130requires1.9MBtuper

hourtoheatthestreamfrom209Fto248Ftopreheatthevaporrecyclestream.StreamS108

requirestheremovalof28,000Btuperhourtocoolthestreamfrom521Fto140Ftocoolthe

sludgestreamtobelowtheOSHAtemperature limitforpersonalprotection.Similarly,stream

S114requirestheremovalof3.2MBtuperhourtocoolthestreamfrom352Fto140Ftocool

theTDI stream tobelow theOSHA temperature limit forpersonalprotection. StreamS101

requirestheremovalof49.5MBtuperhourtocoolthestreamfrom283Fto100Ftocoolthe

vaporstreamexitingthereactortoallowittobeflashedandseparatethevaporcomponentsin

Table6:

Streams

in

reactor

block

that

need

to

be

heated

or

cooled


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58

thestream,whicharesenttothesecondreactor,fromtheliquidcomponentswhicharethen

recycledbacktothefirstreactor.

Thecondenseronthefirstdistillationcolumnrequirestheremovalof729.9MBtuper

houranditneedstocoolthestreamfrom203.1Fto35Faswellascondensethestream.The

reboileronthefirstdistillationcolumnrequires625.5MBtuperhourand itheatsthestream

from465.8Fto517.8Fbeforevaporizingthestream. Thecondenserontheseconddistillation

columnrequirestheremovalof351.8MBtuperhourtocoolthestreamfrom93.2Fto34.1F

andthencondensethestream. Thereboilerontheseconddistillationcolumnrequires182.9

MBtuperhourtoheatthestreamfrom181.9Fto200.7Fandthenvaporizethestream. The

thirddistillationcolumnhasmuchmoremoderateenergyrequirementsbecauseithasamuch

lowerflowrate. Thecondenseronthecolumnonlyrequirestheremovalof8.6MBtuperhour

tocool the stream from114.5F to101.7Fand thencondense it. The reboileron the third

distillationcolumnrequires10.2MBtuperhourtoheatthestreamfrom264.4Fto352.2Fand

thenvaporizethestream. Thiscomestoatotalheatingrequirementof1,094MBtuperhour

andatotalcoolingrequirementof1,143.1MBtuperhour.

Becausethisisanexcessivelyhighenergyrequirement,itisvitalthatcrossstreamheat

exchangebeusedasmuchaspossibletominimizetheutilitiesneedsoftheprocess. First,the

Table7:Streamsinseparationblockthatneedtobeheatedorcooled


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59

streamsthatmustbeheatedbutarehotterthananyofthestreamsthatneedtobecooledare

ruledoutforcrossstreamheatexchange. Bythisprocess,S106(thereboileroutstreamfrom

the firstdistillation column)was ruledout. Similarly,any streams thatneedcoolingbutare

colder than the streams that need heating cannot be used for cross stream heat exchange.

Initially there are no values that match this description. After pairing up the stream two

separateheatexchangernetworksweresetupasshownbyTable8.

Thefirstnetwork,HX1,involves5streams;thecondenserofthefirstdistillationcolumn

isthehotstream forall fourheatexchangers inthenetwork,and it ispairedwith4streams

thatneedheating,S131,S129,S121,andS110. OriginallyS129wasplacedfirstintheorder,

because ithasthehighest initialtemperature,butthennoenergywasavailableforstreamS

131becausethehotstreamwouldleavethefirstheatexchangercoolerthanS131. Becauseof

this,S131andS129werechanged in theorder so that themostenergycouldbe removed

frombothstreams. There is661,000BtuperhourexchangedoverHX11,38.9MBtuper

hourexchangedoverHX12,4.6MBtuperhourexchangedoverHX13,and34.4MBtuper

hour exchanged over HX 1 4. This means that 78.6 MBtu per hour is removed from the

condenser of the first distillation column. After the heat exchange, S131s temperature is

201F and it still needs

322,000Btuperhourtobe

reach 248 F. S129 is at

199Fanditstillneeds39.6

MBtu per hour to be

heatedto248F.S122isat

Table8:Energysavedperstream.


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60

120Fandstillneeds16MBtuperhourtobeheatedto248F,andS110isat96Fandrequires

138.9MBtuperhourtobeheatedto120F. Thehotstreamwas loweredto37F,and itstill

required651.3MBtuperhourtoberemovedforittogetdownto35Fandthencondensethe

stream.

The second network, HX 2, involves three streams; the stream in the reboiler of the

seconddistillationcolumnisthecoldstreamforbothheatexchangers,anditispairedwithS

114andS101whicharebothhotstreamsthatneedcooling. S101isplacedfirstbecauseitis

notashotasS114. 32.5MBtuperhour isexchangedoverHX21,and2.3MBtuperhour

over HX 2 2. This means that 34.8 MBtu per hour is put into the reboiler of the second

distillationcolumn. Aftertheheatexchangers,S101isat184Fanditstillneeds17MBtuper

hourtoberemovedforittogetto100F,andS114isat206Fanditstillneedstoremove0.9

MBtuperhourtogetto140F. Thecoldstreamisraisedto204Fwhichishigherthanitsfinal

temperatureshouldbe,butitstillneeds148.1MBtuperhourtovaporize.

Some streams, such as S108,

were left out of the heat exchanger

networkbecause theenergy that they

would contribute to the network is so

littlethatthetemperaturechangeduetopressuredropovertheexchangerwouldmorethan

offsetthecontributionofthestream. Theremainingstreamsthatwerenot includedintothe

networkdidnothaveasuitablepartner. Thetotalenergysavingsshown inTable9 of113.4

MBtuperhour inbothcoolingandheatingrepresents10.4%oftheheatingrequirementand

Table9:Totalenergysavingsand%energysavedTotal Heat/Cool

Req. (Btu/hr)

Total Heat/Cool

Savings (Btu/hr)

Savings

(% )

1,093,907, 399 113, 387, 268 10.37%

1, 143, 063, 006 113, 387, 268 9.92%


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9.9%ofthecoolingrequirement. Thismeans$240,000issavedincoolingwaterand$3million

insteamcosts.

Other techniques to help lower the utility cost in the distillation columns are also

considered. Oneideaistousetwoparalleldistillationcolumnsinplaceofthefirstdistillation

column(becausethatisthecolumnwheremostoftheutilitycostis). Thisalternative,however,

doesnotsaveanyenergy. It is in fact increasesthecoolingdutyby75%and it increasesthe

heatingdutyby88%. TheseresultscanbeseeninTable10.

Table10:Possibleheatdutysavingssummarybyusingtwoparalleldistillationcolumnsinplace

ofD100

CondenserHeat

Duty(Btu/hr)

ReboilerHeat

Duty(Btu/hr)

Column

Diameter

Reflux

Ratio

D11 638,667,560 586,347,970 9.97 4.95D12 1,277,335,120 1,172,695,940 9.97 4.95

D1 729,892,881 625,253,709 9.57 2.4

Difference 547,442,239 547,442,231

%Difference 175% 188%


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UtilitiesRequirements

Coolingwater

Cooling water is required for all 6 streams that require cooling even after the heat

exchangersystemasseeninTable11. Thecondenseronthefirstdistillationcolumnrequires

morethan20,000,000,000gallonsofcoolingwaterperyear,whichcosts$1.65millionperyear.

Thecondenserontheseconddistillationcolumnrequires11.1billiongallonsofcoolingwater

peryear,whichcomesoutto$891,156peryear. Thecondenseronthethirddistillationcolumn

requires273milliongallonsofcoolingwaterperyear,whichcomesoutto$21,858peryear.

The cooler C100 still requires 541 million gallons per year of cooling water which will cost

$43,259yearly. ThecoolerC102requires28.5milliongallonsperyearofcoolingwaterwhich

willcost$2,277yearly. Thelastcooler,C101,onlyrequires883,000gallonsperyearofcooling

waterwhichwillcost$71ayear.

Table11:Utilitycostofcoolingwater


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Steam

Thebottomofthefirstdistillationcolumnissohotthatsteamcannotbeusedtoheatit

up;insteadafiredreboilermustbeused. Forthisfiredreboiler,fueloilwasusedastheutility.

Theseconddistillationcolumnalsobenefitsifitusesafiredreboilerratherthansteam. Steam

isusedfortheheatersandthethirddistillationcolumnreboilerasseeninTable12. Thethird

distillationcolumncanthoughuseasteamreboiler, itwillrequire70.3millionpoundsof low

pressure steamperyearwhichwill cost$224,799everyyear. TheheaterH100needs1.11

billionpoundsof lowpressuresteamperyear,costing$3.5millionperyear.H101needs175

millionpoundsof lowpressuresteamperyearwhichwillcost$558,794ayear. H102needs

434millionpoundsof lowpressuresteamperyearwhichwillcost$1.4millionayear.H103

requires3.53millionpoundsof lowpressure steamperyearwhichwillcost$11,279ayear.

Finally H104 requires 20.4 million pounds of low pressure steam per year which will cost

$65,356yearly.

Table12:Utilitycostofsteam.


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FuelOilandSolidWaste

The first distillation

columns fired reboiler will

use 2.81 billion gallons per

year of fuel oil which will

cost $4.5 million, and the

second distillation columns

fired reboiler will use 987

million gallons per year of

fueloilwhichwill cost$1.6

million. 1.83millionpounds

ofsolidwasteareproduced

each year by this process

whichmeansthattherewill

beayearlycostof$195,558todumpthewasteinalandfill. Thehandlingandtransportation

costisincludedasapercentageofthetotalfixedcost.ThesevaluesareshowninTable13and

Table14.

Electricity

Table14:Utilitycostoflandfill.

Table13:

Utility

cost

of

fuel

oil.

Utilitytype Landfill

Materialhandled Sludge

Solidwaste

Amount(lb/hr) 230

Amount(lb/year) 1,825,465

Utilitycost

Unitprice:

Landfill($/drylb) $0.10

Adjustedlandfillcost(CEindexfor2010=532.7) $0.11

Costperyear($/year) $194,558


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65

Finally, we also need to supply electricity through the use of electric motors

accompanyingeverypumpwehaveplacedthroughouttheTDIproductionprocess.Thedetails

canbefoundinTable29inAppendix4.

EquipmentListandUnit

Descriptions


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bytheNaIpromoter. Thereactorisapproximately thesizeofthefirstandhasadiameterof

21.85ftandalengthof87.39ft. Itsbaremodulecostis$4,056,812.

CoolerC100:

C100isafixedheadshellandtubecoolerusedtocoolthevaporfromthefirstreactor

systemwhichwillbe fed to the flashdrum. Themain reason for thiscooler is to lower the

temperature of the vapor from the first reactor so that the quantity of the product, TDI,

vaporized inthereactorcanberecoveredandsenttoseparations.Thecooler ismadeoutof

carbonsteelshellwithainchHastelloyCcoatingtopreventcorrosionbytheNaIpromoter.

Thetubesare20ft in length,andtheareaavailableforheattransfer is3913.27ft2. Thehot

vaporstreamentersat184Fand leavesat100F. Thecoolingstreamingentersat90Fand

leavesat120F. Thepressuredrop through the cooler is5psi,and the coolerheatduty is

17,075,650.7Btu/hr. Thebaremodulecostofthiscooleris$88,092.

Flash

drum

F

100:

F100isaverticaltwophaseflashdrumwhichisusedtoseparatethesolventandgases

fromtherestofthematerialinthevaporstreamfromthefirstreactor. Thesolventandgases

aresenttobefurtherreactedinthesecondreactorsystemwhiletheliquidbottoms(TDA,TDI,

Water and remaining CO, O2, TDCARB, and SOVENT) are sent back to R100 as part of

PSEDUOUT. Theflashdrumismadeoutofcarbonsteel. Thevesselhasanestimatedresidence

timeathalf fullof5minutesandavolumeof4957.21 ft3. Thediameter is14.67 ftand the

lengthis29.34ft. Thevesseloperatesatatemperatureof99.91Fandapressureof644.67psi.

Thebaremodulecostoftheflashdrumis$203,926.


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SplitterSP100:

SP100isasplitterusedtosplitS103into0.3S120whichwillbesenttoR102and0.7

S127whichwillsentbacktoR100aspartofPSEUDOUT.

StreamMixerM100:

M100 isused tomodel thecombinationof streamsS116,S119,S120,O2MAKEUP,

andS121whichwillbesenttothesecondreactor.

HeaterH101:

H101isafixedheadshellandtubeheaterusedtoheatthefeedtoR102. Theheateris

madeoutofcarbonsteelshellwithainchHastelloyCcoatingtopreventcorrosionbytheNaI

promoter. Thetubesare20ftinlength,andtheareaavailableforheattransferis1329.88ft2.

Thepressuredropthroughthecooleris5psi,andtheheaterheatdutyis15,958,528.41Btu/hr.

Thebaremodulecostofthisheateris$135,554.

MixerM101:

M101 isusedtomodelthecombinationofstreamsS124,S125,S126,S127,S128,

ANDS129whichwillbemixedtoformthePSEUDLIQstream. Thisstreamwouldbefedtothe

firstreactor.

HeaterH102:

H102isafixedheadshellandtubeheaterusedtoheatthePSEUDLIQstreamwhichwill

berecycledtoR100. Theheater ismadeoutofcarbonsteelshellwitha inchHastelloyC


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coatingtopreventcorrosionbytheNaIpromoter. Thetubesare20ftinlength,andthearea

availableforheattransferis3300.01ft2. Thepressuredropthroughthecooleris5psi,andthe

heaterheatdutyis39,600,089.7Btu/hr. Thebaremodulecostofthisheateris$214,773.

ValveV100:

V100 is a diaphragm valve which is used as a safety measure to separate the high

reaction and low separation pressures in the process. Steam S104, from the first reactor

system, enters the valve at 652.67 psia, and stream S105 leaves the valve at 5 psia. The

pressuredropacrossthevalveis647.67psi. Thebaremodulecostofthisheateris$301,962.

DistillationColumnD100:

D100 is a 20 stage carbon steel distillation column with a Hastelloy C coating to

prevent corrosionby theNaIpromoter. Thecolumnhas19KochFlexitray trayswitha tray

spacingof2ft,andithasaheightof52ft(assuminga10ftforthesumpand4ftforthespace

above the top tray). The column has a diameter of 9.7 ft. There is an estimated 0.15 psi

pressuredropperstage,andthetopstageisat11psi. Tohelpdecreasethenecessarysizeof

the column, it ispacked from stage219withKochFlexipacwithadimensionof500Y. The

columnhasarefluxratioof2.4. Thedistillateisremovedatatemperatureof34.98F,andthe

bottomsisremovedat465.75F. Thebaremodulecostofthiscolumnis$1,219,952.

PumpP100:

P100 is a centrifugal pump which is used to pump the bottoms from D100 to the

secondreactorsystem. ItismadeofcastironandhasainchHastelloyCcoatingtoprevent


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corrosionbytheNaIpromoter. Thepumphasavolumetricflowrateof280.408cuft/hranda

pressurechangeof648.1psiwhilegeneratingaheadof13624.774inches. Thepumpmotoris

assumed to be explosionproof with a shaft rotation of 3600 rotations per minute. The

electricity requirementtorun thepump is12.3198KW,and thepumpefficiency is0.8. This

pumphasabaremodulecostof$57,306.

SplitterSP101:

SP101 isasplitterusedtosplitS107 into0.99S116whichwillbesenttoR102and

0.01S108whichisthesludgefromD100whichwillbesenttostorage.

CoolerC101:

C101isafixedheadshellandtubecoolerusedtocoolthesludgebottomsfromD101

which will be sent to storage. The cooler is made out of carbon steel shell with a inch

HastelloyCcoatingtopreventcorrosionbytheNaIpromoter. Thetubesare20 ft in length,

and the area available for heat transfer is6.61 ft2. The hot sludge stream, S108 entersat

521.1Fand leavesat140F. Thecoolingstreamingentersat90Fand leavesat120F. The

pressuredropthroughthecooler is5psi,andthecoolerheatduty is 27,856.499Btu/hr. The

baremodulecostofthiscooleris$53,159.

PumpP101:

P101isacentrifugalpumpwhichisusedtopumpthetopsfromD100tobefedtoD

101. ItismadeofcastironandhasainchHastelloyCcoatingtopreventcorrosionbytheNaI

promoter. Thepumphasavolumetricflowrateof9784.44cuft/hrandapressurechangeof10


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PumpP104:

P104 isacentrifugalpumpwhich isused topump the tops fromD101 tobe fed to

bothreactors. Itismadeofcastiron. Thepumphasavolumetricflowrateof9155.70cuft/hr

andapressurechangeof648psiwhilegeneratingaheadof11017.68inches. Thepumpmotor

is assumed to be explosionproof with a shaft rotation of 3600 rotations per minute. The

electricity requirementtorun thepump is402.196KW,and thepumpefficiency is0.8. This


SplitterSP102:

SP102 isasplitterusedtosplitS118 into0.28S119whichwillbesenttoR102and

0.72S126whichwillsentbacktoR100aspartofPSEUDOUT.

DistillationColumnD102:

D100isa19stagecarbonsteeldistillation. Thecolumnhas11KochFlexitraytrayswith

atrayspacingof2ft,andithasaheightof36ft(assuminga10ftforthesumpand4ftforthe

spaceabovethetoptray). Thecolumnhasadiameterof4.19ft. Thereisanestimated0.15psi

pressuredropperstage,andthetopstage isat1psi. Tohelpdecreasethenecessarysizeof

thecolumn,itispackedfromstage27withKochFlexipacwithadimensionof2X. Thecolumn

has a reflux ratio of 3.2. The distillate is removed at a temperature of 101.71F, and the

bottomsisremovedat352.20F. Thebaremodulecostofthiscolumnis$385,015.


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PumpP102:

P102isacentrifugalpumpwhichisusedtopumptheTDIbottomsproductfromD102

tostorage. Itismadeofcastiron. Thepumphasavolumetricflowrateof604.575cuft/hrand

a pressure change of 5 psi while generating a head of 131.70 inches. The pump motor is


electricity requirement to run thepump is .32930KW,and thepumpefficiency is0.5. This


CoolerC102:

C102isafixedheadshellandtubecoolerusedtocooltheTDIbottomsproductfromD

102whichwillbesenttostorage. Thecoolerismadeoutofcarbonsteelshell. Thetubesare

20ftinlength,andtheareaavailableforheattransferis135.39ft2. ThehotTDIstream,S113

entersat206Fandleavesat140F. Thecoolingstreamingentersat90Fandleavesat120F.

The

pressure

drop

through

the

cooler

is

5

psi,

and

the

cooler

heat

duty

is

898,760.8

Btu/hr.

Thebaremodulecostofthiscooleris$24,791.

PumpP103:

P103isacentrifugalpumpwhichisusedtopumpthewastewatertopproductfromD

102tostorage. Itismadeofcastiron. Thepumphasavolumetricflowrateof135.091cuft/hr

andapressurechangeof5psiwhilegeneratingaheadof141.07 inches. Thepumpmotor is


electricity requirement to run thepump is .12390KW,and thepumpefficiency is0.3. This



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TFEStorageTankST104:

ST104 isacarbonsteelstorage tankused tohold theTFE solvent. This tankholds3

hoursworthofTFEatatemperatureof248Fandapressureof639.67psia. Thevolumeofthe

vesselis54,571cuft,andithasapurchasecostof$197,296.

WasteWaterStorageTankST105:

ST105isacarbonsteelstoragetankusedtoholdtheWASTEWATER. Thistankholds

1weeksworthofWASTEWATERata temperatureof101.7Fandapressureof6psia. The

volumeofthevesselis22,696cuft,andithasapurchasecostof$104,902.

Sludge/SolidWasteStorageTankST106:

ST106isacarbonsteelrailstoragetankusedtoholdtheSLUDGEfromthebottomsof

D100. Thistankholds1weeksworthofSLUDGEatatemperatureof168Fandapressureof

648psia. Thevolumeofthevesselis395cuft,andithasapurchasecostof$5,679.

TDIProductStorageTankST107:

ST107 isacarbonsteelrailcarstorageusedtoholdtheTDIproduct. Thistankholds

1weeks worth of TDI product at a temperature of 140F and a pressure of 2.01 psia. The

volumeofthevesselis90,520cuft,andithasapurchasecostof$284,026.


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Identification:

Item HorizontalRefluxAccumulatorTank Date: 4/4/2010

ItemNo. D100ACCUMULATOR

No.Required 1

Function: ToaccumulateexcesstopsfromD100tobefedtofedtorefluxpump

Operation: Continuous

Materials

handled: Reflux

Stream

StreamID: S109

Quantity(lb/hr): 978444.3

Composition:

TDA 1.029994

O2 129.9303

CO 7786.079

TDI 39704.15

WATER 8231.36

TDCARB 3.647230

SOLVENT 922591.7

Temperature(0

F): 34.981

Pressure(psi): 2psi

DesignData:

Material: CarbonSteel

Pressure: 2psi

MolarRefluxRatio: 2.4

Height: 12.0848262248967ft

VaporFraction: 0

HoldupTime: 5min

Comments:

Reflux

Accumulator


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Identification:

Item DistillationReboiler Date: 4/4/2010

ItemNo. D100REBOILER

No.Required 1

Function: Toreheatthebottomsofthecolumnwhichwillbereintroducedtothecolumnasvapor


Materials

handled:

D100REBOILER

StreamID: S106


Composition:

TDA 5198.043

O2 1.47E46

CO 3.62E47

TDI 0.702195

WATER 2.27E

22

TDCARB 17850.01

SOLVENT 7.82E18

InletTemperature(F) 465.75

OutletTemperature( 517.842

DesignData:

MaterialofConstruction: CarbonSteelwith1/4inchHastelloycoating

HeatDuty: 625534412Btu/hr

Utilities: 13.9psiSteam

Type: Kettle

Comments:

Reboiler


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Identification: ItemPump Date: 4/4/2010

ItemNo. D101REFLUXPUMP

No.Requi 1

Function: TopumpthetopsofD101toberefedabovethetoptray

OperationContinuous

Materialshandled:

STREAM

StreamID: S117


Composition:

TDA 6.64E44

O2 129.9303

CO 7786.079

TDI 1.45E30

WATER 0.162563

TDCARB 0.0

SOLVENT 922591.7

Temperature(0

F): 34.092

Pressure(psi): 5

DesignData:

Type: Centrifugal

VolumetricFlowRate: 18768.5864395356cuft/hr

PressureChange : 0.0922660000000004psi

ElectricityRequired: 6.63296KW

Efficiency: 0.825443

Comments:

Pump&Motor


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Identification:

Item HorizontalRefluxAccumulatorTank Date: 4/4/2010

ItemNo. D101ACCUMULATOR

No.Required 1

Function: Toaccumulate excesstopsfromD101tobefedtofedtorefluxpump


Materialshandled: Reflux

Stream

StreamID: S117


Composition:

TDA 6.64E44

O2 129.9303

CO 7786.079

TDI 1.45E30

WATER 0.162563

TDCARB 0.0

SOLVENT 922591.7

Temperature(0

F): 34.092

Pressure(psi): 5psi

DesignData:


Pressure: 5psi

MolarRefluxRatio: 1.05

Height: 9.98566090073922ft

VaporFraction: 0

HoldupTime: 5min

Comments:

RefluxAccumulator


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Identification: ItemCondenser Date: 4/4/2010

ItemNo. D101CONDENSER

No.Required 1

Function: TocondensethetopsofD101

OperationContinuous

Materialshandled:

D101Condenser

StreamID: S117


Composition:

TDA 6.64E44

O2 129.9303

CO 7786.079

TDI 1.45E30

WATER 0.162563

TDCARB 0.0

SOLVENT 922591.7

Inlettemperatur(F 34.092

OutletTemperature 34.1

DesignData:

MaterialofConstruction: StainlessSteel

HeatDuty: 351768841btu/hr

Utilities: CoolingWater

Type: Total

Comments:

Condenser


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Identification: ItemPump Date: 4/4/2010

ItemNo. D102REBOILERPUMP

No.Requi 1

Function: TopumpthebottomsofD102toberefedunderneaththebottomtray

OperationContinuous

Materialshandled:

STREAM

StreamID: S113


Composition:

TDA 1.029915

O2 0

CO 0

TDI 39656.97

WATER 4.808312

TDCARB 0

SOLVENT 6.57E12

Temperature(0

F): 352.2

Pressure(psi): 2.0077

DesignData:

Type: Centrifugal


Pressure Change: 0.092266psi

ElectricityRequired: 6.63296KW

Efficiency: 0.498037

Comments:

Pump&Motor


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Identification:

Item RADFRACDistillationColumn Date: 4/4/2010

ItemNo. D102

No.Required 1

Function: ToseparateWaterandTDI


Materials

handled:

InletFeed TopOut BottomOut

StreamID: S112 S115 S113

Quantity(LB/HR): 47936.39 8273.57811 39662.8114

Composition:

TDA 1.029994 0.0 1.02991481

O2 8.18E26 0.0 0

CO 1.06E26 0.0 0

TDI 39704.15 47.1787663 39656.9732

WATER 8231.198 8226.38949 4.80831193TDCARB 0.0 0.0 0.0

SOLVENT 0.009778 0.00977767 6.57E12

Temperature(0

F): Top=101.71,Bot.=352.20

DesignData:


Stages: 12

Pressure: 1psia

Pressure dropperstage: .15psi

Diameter: 4.19ftHeight: 36ft

TraySpacing: 2ft

TrayType: KochFlexitray

Comments:

Distillation

column


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103

Identification:

Item VerticalFlashDrum Date: [Date]

ItemNo. F100

No.Required 1

Function: Toseparatethegasesand solventtobesenttoR102 andliquidbottoms tobesentbacktoR100


Materials

handled:

InletStream TopStream BottomStream

StreamID: S102 S103 S128

Quantity(lb/hr): 292971.018 84460.84 208510.2

Composition:

TDA 1.17130117 5.19E08 1.171301

O2 993.537324 672.3039 321.2334

CO 103246.652 81428.69 21817.96

TDI 34.1342455 0.000107 34.13414

WATER 417.048468 0.228977 416.8195

TDCARB 0.00768696 7.69E13 0.007687

SOLVENT 188278.467 2359.616 185918.9

Temperature(0

F): 99.91


Design

Data:

Material: CarbonSteel with1/4"HastelloyCoating

VaporFraction: 0.525

HalfFullResidenceTime: 5min

Diameter: 14.67ft

Length: 29.34ft

ShellThickness: 0.75in

Comments:

Flash

Drum


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Identification:

Item HEATER Date: 4/4/2010

ItemNo. H100

No.Required 1

Function: TopreheatthetopliquidofD100tobefedtoD101


Materials

handled:

InletStream OutletStream

StreamID: S110 S111

Quantity(lb/hr): 9.7844+05 9.7844+05

Composition:

TDA 1.03 1.03

O2 129.9303 129.9303

CO 7786.079 7786.079

TDI 3.9704+04 3.9704+04

WATER 8231.36 8231.36

TDCARB 3.647230 3.647230

SOLVENT 9.2259+05 9.2259+05

Temperature(0

F): 120

Pressure(psi): 7

Design

Data:

Type KettleVaporizer

MaterialofConstruction: CarbonSteel

PressureDrop 5 psi

HeatDuty Btu/hr

UtilityFluid Low

Pressure

Steam

UtilityRequred 140077 lb/hr

Comments:

Toavoidboiling,assumeheatfluxof12000Btu/hr^2ft^2

Heater

138931683.9


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Identification: Item Pump Date: 4/4/2010

ItemNo. P101

No.Required 1

Function: TopumpthetopsofD100tobefedtoD101


Materialshandled:


StreamID: S109 S110

Quantity(lb/hr): 978444.271 978444.3

Composition:

TDA 1.0 1.0

O2 129.9 129.9

CO 7786.1 7786.1

TDI 39704.152 39704.15

WATER 8231.36036 8231.36

TDCARB 0.0 0.0

SOLVENT 922591.719 922591.7

Temperature(0

F): 35.0177

Pressure(psi): 12

DesignData:

Type: Centrifugal


PressureChange: 10psi

ElectricityRequired: 7.8426kW

Efficiency: 0.8

Comments:

Pump&Motor


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Identification: Item HorizontalReactor Date: 4/4/2010

ItemNo. R100&R101

No.Required 1

Function: Toreactthethestartingmaterialstocreatetheproducts


Materialshandled:

CombinesInletStream OutletStream

StreamID: TDA,O2,CO,SOLVENT,&PSUEDO RX1MID

Quantity(lb/hr): 1.2945+06 1.2945+06

Composition:

TDA 28890.5137 5200.244

O2 7328.4448 1123.468

CO 121898 1.1103+05

TDI 10287 3.9739+04

WATER 1661.7135 8648.409

TDCARB 8567.4708 1.7850+04

SOLVENT 1115795.34 9.2259+05

Temperature(0

F): 282.765


DesignData:

ResidenceTimeatHalfFull: 60min

MaterialofConstruction: CarbonSteelwithHastelloycoating

Type: FixedBedAutoclave Reactor

RXN1HeatofReaction: ()150773.43btu/lbmol

RXN2Heat

of

Reaction: (

)12384.795

btu/lbmol

Volume:

Comments:

Thegaseswillbebubbledupthroughtheliquidcausingthoroughmixing.

AlthoughASPENshowsR100&R101astwoseparatevessels,theywillbe

onesinglevessel.

145609.0ft^3

Reactor


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Identification: Item HorizontalReactor Date: 4/4/2010

ItemNo. R102&R103

No.Requi 1

Function: Toreactthethestartingmaterialstocreatetheproducts


Materialshandled:


StreamID: B4RX2 RX2MID

Quantity(lb/hr): 309882.677 309882.7

Composition:

TDA 5146.0623 926.2912

O2 1422.02726 316.7826

CO 26608.7099 24673.74

TDI 0.69520548 10252.94

WATER 0.11421085 1244.617

TDCARB 17671.5052 8567.389

SOLVENT 259033.563 263900.9

Temperature(0

F): 282.765


DesignData:

MaterialofConstructi on: CarbonSteelwithhastelloycoating

Type: FixedBedAutoclave Reactor

Comments:

Thegaseswillbebubbledupthroughtheliquidcausingthoroughmixing.

AlthoughASPENshowsR102&R103astwoseparatevessels,theywillbe

onesinglevessel.

Reactor


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Identification: ItemVerticalStorageTank Date: 4/4/2010

ItemNo. ST102

No.Required 1

Function: TostoreCO

OperationContinuous

Materialshandled:

Flow

StreamID:


Composition:

CO 12798.09

Temperature(0

F): 248


DesignData:

Material:

HoldingAmount:

Volume:

Diameter: 189.916ft

Length: 31.653ft

TimePeriod:

Type Open

Comments:

StorageTank

896650ft^3

168hours

1week

CarbonSteel


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ItemNo. ST103

No.Required 1

Function: TostoreO2

OperationContinuous

Materialshandled:

Flow

StreamID:


Composition:

O2 7310.222

Temperature(0

F): 248

Pressure(psi): 653

DesignData:

Material:

HoldingAmount:

Volume:

Diameter: 150.308ft

Length: 25.051ft

TimePeriod:

Type Open

Comments:

StorageTank

CarbonSteel

1week

444514ft^3

168hours


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ItemNo. ST104

No.Requi 1

Function: TostoreTFEsolvent

OperationContinuous

Materialshandled:

Flow

StreamID:

Quantity(lb/hr): 1.12E+06

Composition:

TFEsolvent 1.12E+06

Temperature(0

F): 248


DesignData:

Material:

HoldingAmount:

Volume:

Diameter: 74.704ft

Length: 12.451ft

TimePeriod:

Type Open

Comments:

StorageTank

54571ft^3

3hrs

1week

CarbonSteel


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ItemNo. ST105

No.Required 1

Function: TostoreWASTEWATER

OperationContinuous

Materialshandled:

Flow

StreamID:


Composition:

WASTEWATER 8273.578

Temperature(0

F): 101.7

Pressure(psi): 6

DesignData:

Material:

HoldingAmount:

Volume:

Diameter: 55.762ft

Length: 9.294ft

TimePeriod:

Type Open

Comments:

StorageTank

22696ft^3

168hrs

1week

CarbonSteel


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ItemNo. ST107

No.Required 1

Function: TostoreTDI

OperationContinuous

Materialshandled:

Flow

StreamID:


Composition:

TDI 39662.81

Temperature(0

F): 140

Pressure(psi)

Phosgene-free Route to Toluene Diisocyanate (1)

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Transcript of Phosgene-free Route to Toluene Diisocyanate (1)