Abstract
In order to separate phenol-acetophenone azeotrope in pyrolysis products of phenol tar, a process of heat integrated pressure swing distillation (PSD) is proposed for environmental protection and energy saving, where the overhead vapor of high-pressure column is taken as the heat source of low-pressure column reboilers. An activity coefficient model, i.e. universal quasi chemical (UNIQUAC), is chosen as the physical property method for simulation, the feasibility of PSD is studied by the thermodynamic analysis tool of ASPEN, and the pressure of each column was determined too. A general convergence strategy was proposed for PSD process simulation, which can also decouple the interaction between the convergence of recycle stream and the optimization of process parameters. To converge the heat integrated PSD process, a design specification was set to satisfy the mass balance requirement of the process. The simulation results show that 78,236 t/y condensate and 5,397 t/y steam are saved, and total annual cost is reduced by 9.4 % compared with conventional pressure swing distillation.
