Dynamics of a Continuous Distillation of a Mixture of Benzene, Toluene, and p-Xylene
A 10-stage column is fed with a mixture of benzene, toluene, and p-xylene. The feed location is stage 6, its flow rate is 40 kmol/hr, and its composition is 65% benzene, 25% toluene, and 10% p-xylene. Assume that the initial composition in the column's plates, reboiler, and condenser is the same as the feed composition. The molar hold-up of the reboiler, condenser, and plates is 150, 75, and 10 kmol, respectively. The vapor flow rate in the column is 150 kmol/hr. Rigorous column simulation would require fixing the reboiler heat duty and not assuming constant liquid and vapor flow rates in the column. Dynamic simulation is performed for various values of the reflux ratio to be set by the user. Bottom and distillate compositions are displayed (blue curve for benzene, orange curve for toluene, and magenta curve for p-xylene). Steady-state compositions are plotted versus plate numbers for all components of this ternary mixture.