Heat-integrated pressure-swing distillation process for separating the minimum-boiling azeotrope ethyl-acetate and ethanol

Design and control of the forward integration of pressure-swing distillation processes is explored with the aid of the tools of Aspen plus and Aspen dynamics taking the separation of the minimum-boiling azeotrope ethyl acetate and ethanol as an example. The optimized separation configuration is obtained by taking the minimization of total annual cost (TAC) as an objective function. The two key performance indicators of second law efficiency (1) and carbon dioxide emissions are employed to evaluate the three operations, which consist of conventional non-heat integration and the corresponding partially and fully heat integration processes. Compared to the non-heat integration process, the fully heat integration process is more attractive since it can achieve 33.33% energy consumption saving, reduction of 31.33% CO2 emissions and 26.64% TAC. Furthermore, the control of the PSD processes with heat integration are explored since the interaction of parameters are complicated for this neat configuration. The effectiveness of the single-end control strategy is evaluated and determined by method of the feed composition sensitive analysis, and a series of control structures are devised and assessed by the perturbations of the feed flow rate and feed composition. It is concluded that the small disturbances are addressed for fully heat integration in comparison with the partially heat integration owing to the degree of freedom reduction. In addition, the efficient control strategy with the ratio scheme to manipulate the cascade flow controller is developed to eliminate the snowball effect for PSD with partially case.