Aspen Plus Tutorial 1:Vinyl Chloride
Monomer Production Process
Vinyl chloride monomer (VCM) is produced through a high-pressure, noncatalytic process involving
the pyrolysis of 1,2-dichloroethane (EDC), according to the following reactions:
CH2CI-CH2CI (EDC) HCl + CHC1=CH2 (VCM)
The process flow diagram is shown in Figure 1.
The cracking of EDC occurs at 900oF and 300 psia in a direct-fired furnace. The pure EDC feed
enters the furnace at 60oF and 390 psia, with a rate of 2000 lbmol/hr. Byproducts of pyrolysis
consist principally of acetylene and chloroprene through the following reactions:
EDC C2H2 + HCl
VCM + C2H2 C4H5Cl
Overall EDC conversion is maintained at 55%, with a selectivity of 98% for VCM production and
2% for acetylene production. 75% of the acetylene produced is converted to chloroprene.
The hot gases from the furnace are quenched to 10 degrees below saturation, prior to fractionation.
Two distillation columns are used for the purification of the VCM product. In the first column,
anhydrous HCI is removed overhead and sent to the oxychlorination unit. In the second column,
VCM product is delivered overhead, and the bottoms stream containing unreacted EDC is recycled
back to the cracker. The recycle EDC stream is treated, in a black box separator, to remove
chloroprene, which could hinder pyrolysis and fractionation.
Specifications for the two columns are:
HCl in bottoms
50 ppm (weight)
VCM recovery in bottoms
VCM recovery in overheads
EDC recovery in bottoms
Base Case Simulation
Develop a base ASPEN PLUS simulation for the VCM flowsheet, using the following
specifications. Detailed instructions follow these general ones.