Design and Control of a Heat Pump-Assisted Azeotropic Dividing Wall Column for EDA/Water Separation

A novel heat pump-assisted azeotropic dividing wall column (HP-ADWC) has been proposed for the separation of a maximum-boiling ethylenediamine (EDA)/water system in this paper. Compared with conventional azeotropic distillation (CAD), HP-ADWC allows 42.93% energy savings and 24.36% total annual cost (TAC) savings if the payback period is assumed to be 8 years. To achieve the energy and economic benefits, this novel design must be controllable. However, it is challenging to control this complex and highly integrated HP-ADWC process since there are more interactive variables and fewer degrees of freedom than classic DWC process. In this paper, the dynamic controllability of HP-ADWC is studied by Aspen Dynamics and an effective control structure named CS4 is proposed, which works pretty well for the disturbances in both feed rate and feed composition.