Design And Control Of Dividing Wall Distillation Column

Dividing Wall Column(DWC) is a new energy-saving rectification unit with higher thermodynamic efficiency and lower equipment investment costs in the multi-component rectification process than conventional rectification sequences.In recent years,it has gradually become a hot spot for experts in the field of engineering.Taking ethanol-n-propanol-n-butanol as separation system,Using Aspen Plus simulation software,the conventional rectification sequence is rigorously simulated and optimized,the conventional two-column distillation sequence was transformed into the dividing wall column distillation sequence and guarantee the optimal values of the design variable.Study the influence of operating parameters such as reflux ratio,vapor and liquid splitter on the separation effect of the DWC,explore the best operating area and energy saving effect of the DWC distillation sequence.Analysis of the energy saving reasons of DWC by analyzing the liquid phase distribution of C3H8O in the tower.The result demonstrate that the main reason for the energy saving of the DWC distillation sequence is to reduce the back-conversion phenomenon of C3H8O in the conventional distillation sequence,avoid the heat loss of the repeated heating of C3H8O,and at the same time better meet the optimal feed requirements.There is an operation interval in which the reboiler has the least thermal load in the DWC,The operating region in the range of liquid split(R_L)is[0.22,0.24],the vapor split(R_V)is[0.42,0.44],R_Land R_Vare related to each other,one-to-one correspondence.Compared with the conventional distillation sequence,to complete the same separation task,DWC reboiler energy saving 3463.56k W,and the energy saving is about 12.34%.the results show that DWC distillation sequence not only improves the thermodynamic efficiency,but also greatly reduces the equipment investment.Based on the steady-state simulation study,the four-column distillation process was built.The dynamic simulation of the four-column model was carried out by Aspen Dynamics.Using the vapor split as the manipulated variable of the DWC,a temperature-component control strategy was designed to investigate the dynamic response of the three products when the feed flow rate and the feed component were disturbed.The simulation results illustrate that in the face of feed flow rate and composition interference,the mass fraction of the three products can recover to the set value within a period of time,which has good control effect.The vapor split can be used as an effective manipulated variable in the control strategy of DWC,The vapor split can be applied to the control of the DWC.