Experimental Research And Numerical Simulation Of A New Vapor Splitter In DWC

Distillation process has the advantages of continuous operation and large capacity.It is a large energy consumer and widely used in the separation of multi-component mixtures.Compared with conventional distillation column,DWC(Dividing Wall Column)has better energy-saving effect in the separation process.DWC is an internally thermally coupled distillation column,which is thermodynamically equivalent to Petlyuk by installing one or more walls inside the column.DWC can eliminate the backmixing of the middle components in the column,reduce energy consumption and improve efficiency in the separation of mixtures.There are many freedom degrees in DWC,and the complexity of the calculation hinder the vapor split in DWC.Vapor split ratio is a key technologie of industrial application of DWC,so it is necessary to break the bottleneck in order to speed up the process of industrial application of DWC.In order to optimize auto-allocated vapor flow rate on the both side of the wall in real-industry,this paper present a new vapor splitter.In this paper,ANSYS CFD is used to build a three-dimensional model and make a grid.Two-Euler homogeneous multiphase flow model and standard k-ε turbulence model are selected.Through tracking the vapor-liquid two-phase flow state and calculating the vapor flow rate,the results show that the new vapor splitter can allocate the vapor split ratio in DWC.Based on the structural optimization of the device(type I),the type II is put forward.Type II is composed of two identical D-type devices.Finally,a 600 mm diameter column was built to test the performance of the type II with air-water system.The results show that the experimental results are consistent with the simulation results.Based on the energy-saving technology of DWC,this paper provides a complete design method for the separation of mixture system(Hexane-Heptane-Octane).Based on the Fenske-Underwood-Gilliland-Kirkbride,we established a simple design model of three columns and obtained some parameters in the design process of DWC.Finally,we established a strict calculation based on the simple calculation results.Based on the steady-state operation,the dynamic response of the vapor split ratio control structure with or without disturbance of feed flow(±10%)and composition change(±10%)is compared.The results show that the control loop of the structure without the vapor splitter is greatly affected by the disturbance after adding the feed disturbance,and the restoring time is long.The structure with the vapor splitter can effectively reduce the restoring period of equilibrium.