Cyclohexane production workshop

Cyclohexane Production Workshop
Objective: Create a flowsheet to model a cyclohexane production process
Cyclohexane can be produced by the hydrogenation of benzene in the followingreaction:

C6H 6 Benzene

+

3 H2 Hydrogen

=

C6 H12 Cyclohexane

The benzene and hydrogen feeds are combined with recycle hydrogen and cyclohexane before entering a fixed bedcatalytic reactor. Assume a benzene conversion of 99.8%. The reactor effluent is cooled and the light gases separated from the product stream. Part of the light gas stream is fed back to thereactor as recycle hydrogen. The liquid product stream from the separator is fed to a distillation column to further remove any dissolved light gases and to stabilize the end product. A portion ofthe cyclohexane product is recycled to the reactor to aid in temperature control.
Septiembre 12, 2001
®

Introduction to Aspen Plus

Slide 107
©1998 AspenTech. All rights reserved.Cyclohexane Production Workshop
C6 H6 + 3 H2 = C 6H12 Benzene Hydrogen Cyclohexane
PURGE
Total flow = 330 kmol/hr T = 50 C P = 25 bar Molefrac H2 = 0.975 N2 = 0.005 CH4 = 0.02 92% flowto stream H2RCY

H2RCY

VFLOW

H2IN

VAP FEED-MIX RXIN
T = 150C P = 23 bar

REACT HP-SEP RXOUT
T = 200 C Pdrop = 1 bar Benzene conv = 0.998 T = 50 C Pdrop = 0.5 bar

LTENDSTheoretical Stages = 12 Reflux ratio = 1.2 Bottoms rate = 99 kmol/hr Partial Condenser with vapor distillate only Column Pressure = 15 bar Feed stage = 8

BZIN
T = 40 C P = 1 bar Benzeneflow = 100 kmol/hr

LIQ COLFD LFLOW

CHRCY

30% flow to stream CHRCY

Use the RK-SOAVE property method When finished, save as filename: CYCLOHEX.BKP
Septiembre 12, 2001
®

PRODUCTCOLUMN
Specify cyclohexane mole recovery of 0.9999 by varying Bottoms rate from 97 to 101 kmol/hr

Introduction to Aspen Plus

Slide 108
©1998 AspenTech. All rights reserved.