Mass and Energy Balance A styrene (S) production plant is producing S by converting ethylene benzene (EB) in the catalytic dehydrogenation reactor.
engineering
Description
Mass and Energy Balance
A styrene (S) production plant is producing S by converting ethylene benzene (EB) in the
catalytic dehydrogenation reactor. The simplified process flow diagram of the styrene
production plant is given in Figure 1.
Process description Fresh EB and recycled EB are combined and heated from 25°C to 500°C
in the EB preheater (A). The heated EB is then mixed adiabatically with steam at 700°C at
point (B) to produce the feed to the reactor (C) at 600°C. The steam is used to suppress the
undesired side reactions and removes carbon deposited on the catalyst surface. The single
pass conversion at reactor (C) is 35%, and products leave the reactor (C) at 560°C. Then, the
product stream is cooled in a condenser (D), condensing essentially all the water, EB and
styrene, while allowing hydrogen to pass out as a recoverable by-product of the process.
The water and hydrocarbon liquid are immiscible and separated in the decanter (E). The
water is vaporized and heated in the steam generator (F) to produce steam that mixes with EB
feed to the reactor. The hydrocarbon stream that leave the decanter (E) is then sent to
distillation column (series of distillation columns) (G) to separate the mixture into pure S and
EB at 25°C after cooling and condensation of the streams. The EB is recycled back to the
reactor (C), while S is withdrawn as the product. The reaction of converting EB to S is given
in Eq. 1.
