Comparison of alternative distillation processes for the maximum-boiling ethylenediamine dehydration system

An investigation and comparative analysis on the design and control of the maximum-boiling ethylenediamine (EDA) dehydration system is made in this work. Extractive distillation (ED) and heterogeneous azeotropic distillation (HAD) are used to separate EDA/water mixture that forms a maximum-boiling homogeneous azeotrope. 1,4-butanediol (BDO) and n-propyl acetate (NPAC) are selected as the suitable heavy/light entrainer from three candidate ones for each distillation process respectively. Savings of 17.80% in energy consumption and reduction of 26.26% in minimal total annual cost (TAC) can be obtained by comparing optimum design of ED process to that of HAD process for this system. Moreover, an initial control structure (CS) and an improved one are established for each distillation process. Finally, the comparison of dynamic responses indicates that the HAD process represents an alternative at the stand point of dynamic control for this system.