Double Dividing-wall Distillation Column For Separating The Most Favorable System

Reactive distillation technology is widely used because it can reduce the energy consumption and equipment investment in chemical process.The conventional reactive distillation column(CRDC)has high energy-saving potential due to the high coupling degree between reaction and separation operations in separating the reacting mixtures with the most favorable relative volatility ranking.However,the energy consumption of separation between reactants and products is high when the unfavorable reaction kinetics(low reaction rate,low conversion and low selectivity)cause the accumulation of reactants in the rectifying and stripping section.Therefore,it is necessary to improve the conventional reaction distillation column through a new structural design.In this thesis,based on the advantages of reactive distillation and dividing-wall distillation technology,an effective process intensification principle for reactive distillation is innovatively proposed,and the improvement of conventional reactive distillation column is demonstrated by incompletely separating the mixing components in the column and leading them into the dividing-wall distillation column for subsequent separation on the purpose of enhancing the mass and energy coupling between the separation operations.Subsequently,further integrating the mass transfer between two columns,an effective reactive double dividing-wall distillation column(R-DDWDC)was obtained,which can significantly improve the energy efficiency in the process.Taking ideal quaternary reversible reaction and transesterification of dimethyl carbonate and ethanol as examples,different structural models were built in Aspen Plus software,and the optimal configuration of each structure was obtained for the object of minimizing the reboiler heat duty,thus achieving the evaluation and analysis of the proposed reactive double dividing-wall distillation column.In addition,the influence of parameters of reaction system(relative volatility and chemical equilibrium constant)on energy-saving effect of different structures was discussed in this thesis.The structure performance was evaluated in detail by comparing liquid phase,reaction temperature and reaction rate distribution in different structures.The results show that the reboiler heat duty of the R-DDWDC in the two systems are reduced by 17.91% and 18.62% respectively compared with that of the conventional structure,and it has better steady-state performance.The results of the parametric analysis show that the R-DDWDC is suitable for systems with difficulty in reaction and separation,and also has superior and robust steady-state performance.In conclusion,the R-DDWDC should be introduced in the process of separating the most favorable reacting systems with unfavorable kinetic properties to save energy.