Energy-saving Study On Two Side-products Dividing Wall Column

Dividing wall column(DWC),as a heat integration device shows great potential for energy saving in the multi-component distillation process.For the separation of three components,the energy-saving effect of DWC can reach about 30%.There are industrial application examples at home and abroad.This dissertation mainly studies the technology of DWC with two side-products which aims at the separation of four and more components.It has greater potential for energy saving compared to the separation of the three components of DWC with one side,the theoretical energy saving effect can reach 40%~50%,and has a broad industrial application prospects.The main tasks of this dissertation are: Experimental studies were conducted on two side-products dividing wall column for separating the ideal four-component alcohol.The liquid split ratio and the intermediate components of feeding were examined for the column separation performance and the temperature difference between the two sides of the vertical partition.The results show,under normal temperature conditions,that the separation effect of the column is good when the liquid split ratio is from 0.25 to 0.33 and the intermediate component content is from 50% to 66.7%.In addition,a short-cut design algorithm is proposed.Through rigorous simulation the energy-saving mechanism of the dividing wall column was analyzed,the energy consumption and the thermal efficiency of the dividing wall column were compared to traditional three-column sequence.The results show that the dividing wall column greatly reduces the “backmixing” of the two intermediate components inside the column,which can save energy consumption by 35.65% and improve the thermodynamic efficiency by 26.11%.Separation of C9~C17 paraffin oil mixtures from DWC with two side-products was studied for industrial applications.The industrial small-scale test of DWC with one side product and two side-products was completed,which provides basic experimental data for industrial production.The experimental results show that the change of the liquid split ratio during the production has a great influence on the purity of the one side product.When the liquid split ratio is about 0.33,the purity of DWC is the highest.The production of DWC with two side-products is more complex with respect to one side product,and the coupling between internal streams is greater and the control is also more difficult.The experimental results show that changing liquid split ratio also make the two side-products highest purity value,but the purity of the products decrease significantly compared with the purity of the one-side product.Therefore,the adjustment of the vapor split ratio should be considered simultaneously for the two-side production process.DWC with one side product was used to replace the conventional two-column sequence for separating C12,and the process was strictly simulated and optimized.The optimization results display liquid split ratio is 0.35,the side product quality purity reaches 99%,and the energy saving effect is 24.24%.The two side-products structure is theoretically analyzed and the structure was used to realize the replacement of the four-column in the original process.Multi-factor optimization method was used to simultaneously optimize the vapor and liquid split ratios and the reflux ratio to achieve a quality purity of 99% on both side-produces.The rigorous simulation optimization results show that the optimal vapor split ratio is 0.71,and the optimal liquid split ratio is 0.54.The recovery rate of the side products can reach 98%,which can save 30.67% of theoretical stages,and the energy-saving effect is 41.24%.