The Economic Optimization Of Pressure-swing Distillation Based On Simulated Annealing Algorithm

The economic optimization of pressure-swing distillation has a critical impact on saving investment in equipment and reducing energy consumption.In this paper,the software optimization methods based on sequential iterative optimization and simulated annealing algorithm are proposed.Take the pressure-swing distillation processes of acetone-methanol and methanol-chloroform azeotropic systems for examples,the proposed optimization method is studied and discussed.Using chemical process simulation integration technology,Aspen Plus automation server is invoked by Visual Basic,the annual total cost(TAC)is used as the objective function and combined with the theoretical basis of traditional sequential iterative optimization method to develop the pressure-swing distillation optimization software based on sequential iterative method and form the corresponding optimization method.The move generator criterion and the cooling schedule of the simulated annealing algorithm were analyzed and discussed.The simulated annealing algorithm is combined with the process simulation integration technology to realize the software development based on process simulation and simulated annealing algorithm and put forward the corresponding optimization method.The two optimization methods were applied to the economic optimization of acetone-methanol,methanol-chloroform azeotropic systems with heat integration and without heat integration pressure-swing distillation,respectively.The results show that the two proposed optimization methods all can obtain better TAC value than the traditional optimization methods.The economic optimization results of pressure optimized pressure-swing distillation show that: for the acetone-methanol system,the optimal TAC of no heat integration and partial heat integration pressure-swing distillation process is reduced by 17.32% and 15.52%,respectively.For the acetone-methanol system,the optimal TAC of no heat integration and full heat integration pressure-swing distillation process is reduced by 9.04% and 4.05%,respectively.Compared with the optimization results of the pressure specified,the pressure optimized economic optimization process can significantly reduce the TAC value of objective function.Therefore,the optimization of the operating pressure of the two columns is of great importance to the economic optimization of the pressure-swing distillation and its heat integration process.The re-optimization results of heat integration pressure-swing distillation show that for the methanol-acetone azeotropic system with more optimal process trays number,the optimal TAC of the heat integration process decreases a lot.For the acetone-chloroform azeotropic system with less optimal process trays number,the decreases of TAC is smaller.The optimization methods that based on sequential iterative software and simulated annealing algorithm have the advantages of easy to obtain better TAC value,less time-consuming calculation,automatic or semi-automatic operation,and can be used for other binary azeotropic systems economic optimization and industrial design of pressure-swing distillation.