Simulation And Dynamic Control Of Acetic Acid Dehydration Process Via Heterogeneous Azeotropic Distillation

In this paper, the key issuses of heterogeneous azeotropic distillation process such as process simulation, multiple steady states and control, were studied by using the Aspen plus and Aspen Dynamic software in the acetic acid dehydration system. Through the residual curve analysis, the operational area of this system was obstained firstly. Both of the systems without impurity and with impurity were simulationed and analyzed in this paper. The difference of temperature profiles and composition profiles between two systems were analyzed, and the influence of impurites on distillation process was also studied. Based on the simulated steady state, the requried flow rate of aqueous reflux under different feed composition was simulated, and a method for aqueous reflux flow rate control via expert control was suggested. Then, the sensitivity analysis was carried out for both systems. The phenomenon of multiple steady states in acetic acid dehydration system was studied. A method of process simulation was proposed to deal with the problem that the simulation calculation was not easy converge to the desired steady state. Finaly, a control strategy was desigened for the acetic acid dehydration system. The controlled temperature of sensitivity plate needed pressure add and the flow rate of the solvent add stream was controlled according to the flow rate of steam flow in the top of the column. Step disturbance testing results showed that the control scheme had good dynamic control effect.