Synthesis And Design Of Internal Thermal Coupled-top Dividing Wall Column For Separating Narrow Boiling Point Mixture

For the separation of ternary systems dominated by light components,the top dividing wall column is located at the upper part.TDWC can significantly reduce the energy consumption of the system(compared with the conventional distillation process),but the temperature difference between the top and bottom of the tower is large,that is,the system is high irreversibility,there is still the possibility of further improvement.In order to solve this problem,internal thermally coupled-top dividing wall column(ITC-TDWC)structure design for the separation of narrow boiling point terpolymer systems dominated by light components was presented in this paper.Heat was extracted from both sides of the isolation wall and supplied to the common distillation section.Internal thermal coupling can be achieved either plate-by-plate(TITC-TDWC)or partially ITC-TDWC(PITC-TDWC).For simplified ITC-TDWC(SITC-TDWC),it is possible to implement a small number of heat exchangers on both sides of the isolation wall and between the common extractor section.Therefore,ITC-TDWC is characterized by diversity and complexity.The introduction of internal thermal coupling is likely to reduce the system’s demand for external heat transfer and thus reduce the system energy consumption.The temperature distribution of ITC-TDWC is the key factor to determine its design.In order to obtain the optimal design of ITC-TDWC,this paper firstly determines the optimal structure of ITC-TDWC according to the temperature distribution,and then determines the optimal operating conditions and structural parameters through the heuristic search algorithm.The feasibility and effectiveness of the proposed method were verified by the separation of methanol,ethanol and n-propanol ternary systems with different feed ratios of methanol.The simulation results show that introducing internal thermal coupling can improve the thermodynamic efficiency of TDWC and reduce the irreversibility of the system.Compared with TDWC,THE energy consumption of TITC-TDWC,PITC-TDWC and SITC-TDWC is significantly reduced.For the selected instance,PITC-TDWC and SITC-TDWC have the best steady-state performance.