Simulation On Heat Pump Assisted Dividing Wall Column

Distillation is the most widely used separation method in petroleum and chemical industry.However,the distillation process consumes significant energy.The energy efficiency of the distillation process can be raised if the distillation equipment can be improved,which will bring enormous environmental and economic benefits to the society.Energy saving and intensification technologies of the distillation process has therefore been a hot area of research.Both the heat pump（HP）distillation and the dividing wall column（DWC）are effective distillation process intensification technology which have been widely investigated.The HP distillation can effectively reduce the energy consumption and CO₂ emissions of the distillation process,which has made outstanding contributions to energy conservation and environment protection.DWC can reduce the energy consumption of distillation process with the additional benefit of reducing the capital costs.Although the HP distillation and DWC have been studied by many researchers in recent years,little research has been done on the coupling of HP distillation and the DWC.In this paper,the heat pump assisted dividing wall columns（HP-DWCs）are proposed for three different systems.Firstly,the conventional two-column extractive distillation process for the separation of acetone and ethanol is modified to establish extractive dividing wall column（EDWC）and three HP-DWCs.However,since the temperature difference between the top steam and bottom reboilers is too large,the overhead vapor stream can not act as a heat source for the bottom reboiler,and therefore is used to heat the intermediate reboiler.The total annual cost（TAC）and energy consumption of HP-EDWC-II are reduced by 41.49%and 32.31%respectively when compared with conventional extractive distillation process.Subsequently,taking the preparation of methyl acetate as the research system,the conventional reactive distillation process is improved.The reactive dividing wall column（RDWC）and two HP assisted RDWC configurations are established.The TAC and energy consumption of HP-RDWC-II are reduced by 27.09%and 49.89%respectively when compared with conventional reactive distillation process.Finally,the dehydration of ethlenediamine system is studied.The configurations of azeotropic dividing wall column（ADWC）and four HP distillation assisted ADWC are estabilished.As the temperature difference between the top steam and the bottom reboiler is relatively small,the overhead vapor stream can be used as the heat source of the reboiler.The TAC and energy consumption of HP-ADWC-IV are reduced by 36.40%and 61.73%respectively when compared with conventional azeotropic distillation process.All the configurations proposed in this paper are optimized by the sequential iterative optimization algorithm.The TAC is taken as the optimization objective to compare the economic and environmental benefits of proposed configurations.The calculation results show that all the proposed HP-DWCs can reduce energy consumption and TAC compared with the conventional distillation process,demonstrating that the HP-DWC has good application value.