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Process description

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The process involves mixing ethylbenzene feed with steam in a mixer before entering two heat exchangers to raise the temperature to 600 degrees Celsius. The heated mixture then enters a second mixer where it is mixed with more steam before entering two adiabatic reactors. After exiting the reactors, the stream enters more heat exchangers and a condenser to cool it to 40 degrees Celsius. It then enters a decanter where light gases are separated overhead and an organic stream goes to two distillation columns to separate ethylbenzene, toluene, benzene, and the desired product of 99.5% pure styrene.

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ProcessDescription Ethylbenzene feedof purity0.99 mol % ( impuritybeingBenzene)isfedintothe processatambient conditions,thatisP=1atm and T=25 degrees Celsius. A splittertakesinLowpressure steamandsplitsitbetweenfurnace 1and the mixerassociatedwith the ethyl benzene feed. The Ethylene feedismixedwithlowpressure steamat1 atm comingfromthe splitterandmore Ethyl benzene comingfromthe Ethyl benzene recycle streamfromdistillationcolumnnumber2. Steamisreportedto lowerthe pressure of Ethyl benzene byvirtue of beingadiluent,andsince the reactionthat converts Ethyl benzene tostyrene andhydrogenisreversible,the forwardreactionis favoured. Thismixedfeedisthen chargedintothe processthroughtwocountercurrentheat exchangernetworksinordertoheatup the streamto approach a reactor inletTemperatureof ca 600 degrees Celsius(Luyben2011a).The reactors are adiabatic. Afterthe secondheatexchangerthe mixedfeedstream entersamixer,uponwhich itisagainmixedwithsteamfromFurnace 2 whichis operatingat900K. A lotof steamischarged intothe processbecause the highheatcapacityof water preventsatemperature swingthatcomesaboutbecause the reactionisendothermic.Steamalso removes coke fromthe promotedironcatalyst( DesignBrief). From thismixer,the temperature of the Ethyl benzene streamisnow 603 degrees Celsius andso, the streamentersthroughthe firstreactor,exits,thenentersathirdheatexchanger, whichheatsup the streamagain because the reactionisanendothermic.Fromthe thirdheatexchangerthe product streamfrom the firstreactornow entersreactor2 at a temperature of 597 degrees Celsius. The Temperature issetat approximately600 degrees Celsiusbecause the reactionisendothermic. HigherTemperaturesare avoidedbecausetheyleadtothe propagationof side reactions. The productstream fromreactor 2 is sentthroughheatexchangernumber2 andthenintoheat exchangernumber1in orderto heatup the incomingfeedstream. Fromthe heatexchanger1the productstream fromreactor 2 now goesto the condenserwhichcoolsdownthe streamtothe required40 degrees Celsius. Thereafter,the streamgoesintoadecantor ( 1atm & 40 degrees Celsius),whichconsistsof alight gas splitterwhichtakeslightgasesoverheadand awater organicphase inthe bottomstream, that goesintothe water- organicsplitter. Splitfactorsforthe lightgas splitterwere obtainedfrom (Luyben2011) were [0.013893 0.009568 0.103303 0.034065 0.999367 1 0.966976 0.359118] for [EB S B T H E CO2 W] respectively (Luyben2011a). For the water- organicsplitterpure wateris removedviathe bottomstreamandeverythingelsewith5mol% watergoesoverheadtothe first distillationcolumn. The water- organicsplitter,whichisalsoapart of the decantor,haspure water leavinginthe bottomsstreamandthe organic phase leavingoverhead. The overheadforthisfirstcolumn withsplitsfactors[11 1 1 1 1 1 0 1 0.001123] for [T B C0 C02 E H M S W EB] respectivelyhastoluene ,benzene andlightgases.The bottomsstreamgetsintothe seconddistillationcolumn [0.00332 0.998 0.74] for [SB T] respectively (Luyben2011a),whichhas the overheadasan Ethyl benzene recycle andbottomstreamincludingthe productstyrene. An orderof volatilityandboilingpointswheretakingintoconsiderationfordistillationcolumns The purityof the Styrene is99.5% witha mass flow rate of 200 117ton/year.

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Process description

  • 1. ProcessDescription Ethylbenzene feedof purity0.99 mol % ( impuritybeingBenzene)isfedintothe processatambient conditions,thatisP=1atm and T=25 degrees Celsius. A splittertakesinLowpressure steamandsplitsitbetweenfurnace 1and the mixerassociatedwith the ethyl benzene feed. The Ethylene feedismixedwithlowpressure steamat1 atm comingfromthe splitterandmore Ethyl benzene comingfromthe Ethyl benzene recycle streamfromdistillationcolumnnumber2. Steamisreportedto lowerthe pressure of Ethyl benzene byvirtue of beingadiluent,andsince the reactionthat converts Ethyl benzene tostyrene andhydrogenisreversible,the forwardreactionis favoured. Thismixedfeedisthen chargedintothe processthroughtwocountercurrentheat exchangernetworksinordertoheatup the streamto approach a reactor inletTemperatureof ca 600 degrees Celsius(Luyben2011a).The reactors are adiabatic. Afterthe secondheatexchangerthe mixedfeedstream entersamixer,uponwhich itisagainmixedwithsteamfromFurnace 2 whichis operatingat900K. A lotof steamischarged intothe processbecause the highheatcapacityof water preventsatemperature swingthatcomesaboutbecause the reactionisendothermic.Steamalso removes coke fromthe promotedironcatalyst( DesignBrief). From thismixer,the temperature of the Ethyl benzene streamisnow 603 degrees Celsius andso, the streamentersthroughthe firstreactor,exits,thenentersathirdheatexchanger, whichheatsup the streamagain because the reactionisanendothermic.Fromthe thirdheatexchangerthe product streamfrom the firstreactornow entersreactor2 at a temperature of 597 degrees Celsius. The Temperature issetat approximately600 degrees Celsiusbecause the reactionisendothermic. HigherTemperaturesare avoidedbecausetheyleadtothe propagationof side reactions. The productstream fromreactor 2 is sentthroughheatexchangernumber2 andthenintoheat exchangernumber1in orderto heatup the incomingfeedstream. Fromthe heatexchanger1the productstream fromreactor 2 now goesto the condenserwhichcoolsdownthe streamtothe required40 degrees Celsius. Thereafter,the streamgoesintoadecantor ( 1atm & 40 degrees Celsius),whichconsistsof alight gas splitterwhichtakeslightgasesoverheadand awater organicphase inthe bottomstream, that goesintothe water- organicsplitter. Splitfactorsforthe lightgas splitterwere obtainedfrom (Luyben2011) were [0.013893 0.009568 0.103303 0.034065 0.999367 1 0.966976 0.359118] for [EB S B T H E CO2 W] respectively (Luyben2011a). For the water- organicsplitterpure wateris removedviathe bottomstreamandeverythingelsewith5mol% watergoesoverheadtothe first distillationcolumn. The water- organicsplitter,whichisalsoapart of the decantor,haspure water leavinginthe bottomsstreamandthe organic phase leavingoverhead. The overheadforthisfirstcolumn withsplitsfactors[11 1 1 1 1 1 0 1 0.001123] for [T B C0 C02 E H M S W EB] respectivelyhastoluene ,benzene andlightgases.The bottomsstreamgetsintothe seconddistillationcolumn [0.00332 0.998 0.74] for [SB T] respectively (Luyben2011a),whichhas the overheadasan Ethyl benzene recycle andbottomstreamincludingthe productstyrene. An orderof volatilityandboilingpointswheretakingintoconsiderationfordistillationcolumns The purityof the Styrene is99.5% witha mass flow rate of 200 117ton/year.