Design And Control Of Distillation System For Isopropyl Alcohol/Diisopropyl Ether Separation Using Extractive Distillation And Pressure Swing Distillation

Di sopropyl ether and isopropyl alcohol are both important raw material for fine chemical, solvent. Di sopropyl ether and isopropyl alcohol forms a binary minimum-boiling homogeneous azeotrope at atmosphere pressure. Thus, a diisopropyl etherisopropyl alcohol mixture cannot be separated effectively through a simple distilla t io n process. Two new methods for diisopropyl ether-isopropyl alcohol separation were presented by using extractive distillation(ED) and pressure swing distillatio n(PSD) with 2-methoxyethanol as an entrainer. Chemical process simulation software Aspen Plus was used to implement rigorous steady state simulations. To obtain the optimized configurations for the two processes,sequential iterative optimization procedures combining global economical optimization with partial economical optimization were recommended. The ful y heat-integrated pressure-swing distillation conserves 7.97% energy consumption and reduces 5.75% TAC compared with extractive distillation.Whether a design can be applied in practice strongly depends on dynamic performance of the control system. Commercial software Aspen Dynamics was used to implement dynamic simulations, and the effectiveness of control schemes was tested. For the ful y heat-integrated pressure-swing distillation, two control schemes using PI controllers were explored. Dynamic simulation results showed that, the basic control scheme CS1 could not maintain the quality specifications due to the pressure fluctuat io n. On the basis of CS1, an improved control scheme CS2 was proposed by the introduct io n of pressure-compensated temperature control and QR1/F temperature control. The corresponding dynamic responses showed that, the dynamic control performances of control scheme CS2 are evidently improved, it works effectively for the same feed flow rate and feed composition disturbances. It does a very good job in maintaining the two products' quality. For the extractive distillation process, CS3 and CS4 control schemes using PI controllers were explored. An improved control structure with R/F ratio scheme is used to maintain the two products' purity requirements for the same feed flow rate and feed composition disturbances. And the dynamic performances of CS4 and CS2 are somewhat similar.