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: Purpose Synthesis step Basic processing operation Equipment required
1 To mix the raw material as per the ratio required for reaction Distribution change Mixing of streams Mixer
2 To increase the pressure of feed mixture required to reactor conditions Pressure difference Change in pressure Compressor
3 To increase the temperature required to meet the reactor conditions Temperature difference Change in temperature Heat exchanger
4 Conversion of raw material to product Molecular change Chemical reaction Reactor
5 To separate the product and unconverted raw material Phase elimination Phase separation Separator

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

S.No Block names ASPEN models Equipment Unit Process
1 MIX Stream Mixer Mixer Benzene  and propylene mixing block
2 HEATER Heater Heat exchanger To heat up the feed to required reaction temperature
3 B3 Compr Compressor To increase the recycle benzene pressure to reactor feed pressure
4 PBR Rplug Packed bed reactor Fixed bed plug flow reactor for  cumene production
5 Cooler Heater Cooler To remove the heat from the reactor product stream
6 SEP1 DSTWU Distillation column(winn- underwood gilliland method) To separate propane from reactor effluent
7 SEP2 DSTWU Distillation column To separate benzene from reactor effluent
8 SEP3 DSTWU Distillation column To separate cumene and DIPB
9 B4 FSplit Splitter To 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.

1 2 3 4 5 6 7 8 9 BENZENE CUMENE DIPB FUELGAS MIX PROPYLEN RECYCLE
Temperature K 298.9 320.9 320 425.2 373.1 473.5 358.7 356.5 356.5 298 371.9 440.4 275.5 435.8 298 356.5
Pressure    atm 35 35 35 34 24 12 35 1.1 1.1 35 0.2 0.4 5 1.3 35 1.1
Vapor Frac 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Mass Flow   kg/sec 276.522 437.379 437.379 437.41 437.41 435.184 160.858 160.858 160.858 234.341 111.026 2.442 2.226 113.468 42.181 321.717
Volume Flow cum/sec 0.339 0.536 0.535 0.6 0.55 0.685 0.196 0.197 0.197 0.264 0.139 0.003 0.004 0.155 0.084 0.394
Enthalpy    MMkcal/hr 126.17 228.347 227.746 227.746 187.297 274.364 102.177 101.289 101.289 128.121 -19.183 -1.056 -5.274 -7.337 -1.951 202.577
Density     kg/cum 815.326 816.207 817.254 728.512 795.193 635.257 820.671 815.955 815.955 886.712 801.455 744.962 525.799 732.697 501.637 815.955
Mole Flow   kmol/sec
PROPYLENE 0.95 0.95 0.95 0 0 0 0 0 0 0 0 0 0 0 0.95 0
BENZENE 3 5.059 5.059 4.123 4.123 4.122 2.059 2.059 2.059 3 0.004 0 0 0.004 0 4.118
ISOPR 0 0 0 0.922 0.922 0.922 0 0 0 0 0.921 0.001 0 0.922 0 0
P-DII 0 0 0 0.014 0.014 0.014 0 0 0 0 0 0.014 0 0.014 0 0
PROPANE 0.05 0.05 0.05 0.05 0.05 0.001 0 0 0 0 0 0 0.05 0 0.05 0.001

Aspen plus process flowsheet of cumene production:

Cumene production simulation process diagram

Preliminary flowsheet design of cumene synthesis