Dynamic control analysis of interconnected pressure-swing distillation process with and without heat integration for separating azeotrope

Dynamic controls of pressure-swing distillation with an intermediate connection (PSDIC) process of ethyl acetate and ethanol separation were investigated. The double temperature/composition cascade control structure can perfectly implement effective control when ±20% feed disturbances were introduced. This control structure did not require the control of the flowrate of the side stream. The dynamic controllability of PSDIC with partial heat integration (PHIPSDIC) was also explored. The improved control structure can effectively control ±20% feed disturbances. However, in industrial production, simple controller, sensitive and easy to operate, is the optimal target. To avoid the use of component controllers or complex control structure, the original product purities could be maintained using the basic control structure for the PSDIC process if the product purities in steady state were properly increased, albeit by incurring a slight rise in the total annual cost (TAC). This alternative method without a composition controller combined with the energy-saving PSDIC process provides a simple and effective control scheme in industrial production.