The Optimization Method Of Dividing Wall Distillation Column

At present,saving energy and reducing energy consumption is still a major tough issue.Distillation,as the largest energy consumption unit operation in industrial process,is one of the most widely used separation technique in contemporary chemical production.It is of great significance to research the energy saving technology in distillation process for the chemical industrial production.The improvement of distillation technology is one of the most effective methods to reduce the energy consumption in the distillation process.Dividing wall column(DWC),as a special thermal coupling distillation,can achieve the goal of reducing energy consumption in distillation.This paper mainly focuses on the optimization method of DWC.Firstly,the structure characteristic,separation specialty,energy-saving principle of DWC and the optimization of multi-objective problems in the process are analyzed.On this basis,the characteristics of the sequence quadratic programming(SQP)and(Non-dominated Sorting Genetic Algorithm II,NSGA-II)have been introduced in detail.This paper uses the DWC as the research object,applying the process simulation software Aspen Plus to deal with the process design and optimization of DWC,then compared with conventional distillation.The SQP method embedded in the process simulator Aspen Plus and non-dominated sorting genetic algorithm II(NSGA-II)written in MATLAB are used for optimal design of DWC.Two application case studies are investigated to verify the economic advantages of DWC.The main tasks are as the follows:DWC is applied in the separation of benzene-toluene-xylene,simulated with Aspen Plus.The operation parameters are determined by the methods of SQP and NSGA-II in this process,such as the number of theoretical plates in main column,reflux ratio,feed location,the number of theoretical plates in prefractionator,vapor and liquid split ratio,side stream location and connection location of interconnected streams.The result shows that the total annual cost(TAC)can be saved 25.38% optimized by SQP method and reduced 26.92% using NSGA-II in DWC compared with the results of conventional distillation process.DWC is applied in azeotropic distillation in order to separate tert-butanol and water.The process parameters are obtained by the methods of SQP and NSGA-II in the ADWC process.Compared with the conventional azeotropic distillation,the TAC can be saved 29.05% optimized by SQP method and reduced 29.85% using NSGA-II in ADWC.This paper has provided the theoretical basis for the application of genetic algorithm used to solve multi-objective optimization problems in DWC and ADWC.It has profound guiding significance for the optimization of DWC.