Aspen Plus Process Flowsheet for Cumene Production

Aspen plus works perfect for chemical process studies. Process flowsheet development in it is much easier and user friendly. An example flow sheet is shown here that simplifies the study of cumene production using benzene and propylene as raw materials and produce cumene as main product. Time needed to understand the process behavior and to do material and energy balance calculation is much less with it. On fundamental ideology, a chemical process needs to have a mixing, reacting and separation system. Raw materials are mixed brought to reacting condition allowed for reaction to occur and finally the separation of product from unreacted raw material is the sequence of unit operation conducted in any kind of process industry.
For cumene production, basic processing operations chosen are:

Step No:PurposeSynthesis stepBasic processing operationEquipment required
1To mix the raw material as per the ratio required for reactionDistribution changeMixing of streamsMixer
2To increase the pressure of feed mixture required to reactor conditionsPressure differenceChange in pressureCompressor
3To increase the temperature required to meet the reactor conditionsTemperature differenceChange in temperatureHeat exchanger
4Conversion of raw material to productMolecular changeChemical reactionReactor
5To separate the product and unconverted raw materialPhase eliminationPhase separationSeparator

List of elements in Aspen plus process flowsheet for cumene production:

S.NoBlock namesASPEN modelsEquipmentUnit Process
1MIXStream MixerMixerBenzene  and propylene mixing block
2HEATERHeaterHeat exchangerTo heat up the feed to required reaction temperature
3B3ComprCompressorTo increase the recycle benzene pressure to reactor feed pressure
4PBRRplugPacked bed reactorFixed bed plug flow reactor for  cumene production
5CoolerHeaterCoolerTo remove the heat from the reactor product stream
6SEP1DSTWUDistillation column(winn- underwood gilliland method)To separate propane from reactor effluent
7SEP2DSTWUDistillation columnTo separate benzene from reactor effluent
8SEP3DSTWUDistillation columnTo separate cumene and DIPB
9B4FSplitSplitterTo split the recycle stream into purge and recycle loop

Simulation is done with benzene recycle stream with the input of benzene 3 kmol/Sec and propylene 1 kmol/Sec. The material and energy balance table is shown below. 2.059 kmol/Sec of benzene recycle and purge obtained for 0.925 kmol/Sec of cumene produced, along the byproduct 0.0152 kmol/Sec of diisopropylbenzene.

123456789BENZENECUMENEDIPBFUELGASMIXPROPYLENRECYCLE
Temperature K298.9320.9320425.2373.1473.5358.7356.5356.5298371.9440.4275.5435.8298356.5
Pressure    atm353535342412351.11.1350.20.451.3351.1
Vapor Frac0000000000000000
Mass Flow   kg/sec276.522437.379437.379437.41437.41435.184160.858160.858160.858234.341111.0262.4422.226113.46842.181321.717
Volume Flow cum/sec0.3390.5360.5350.60.550.6850.1960.1970.1970.2640.1390.0030.0040.1550.0840.394
Enthalpy    MMkcal/hr126.17228.347227.746227.746187.297274.364102.177101.289101.289128.121-19.183-1.056-5.274-7.337-1.951202.577
Density     kg/cum815.326816.207817.254728.512795.193635.257820.671815.955815.955886.712801.455744.962525.799732.697501.637815.955
Mole Flow   kmol/sec
PROPYLENE0.950.950.95000000000000.950
BENZENE35.0595.0594.1234.1234.1222.0592.0592.05930.004000.00404.118
ISOPR0000.9220.9220.92200000.9210.00100.92200
P-DII0000.0140.0140.014000000.01400.01400
PROPANE0.050.050.050.050.050.0010000000.0500.050.001

Aspen plus process flowsheet of cumene production:

Cumene production simulation process diagram

Preliminary flowsheet design of cumene synthesis