Investigation Of Effect Of Vapor Split Ratio Decision In Design On Operability For DWC By Numerical Simulation

Distillation separation is one of the most important unit operations in chemicalindustry, especially oil-refining industry, and in all the separation processes, it is theoldest and the most mature technology. However, it also requires the most amount ofenergy in the whole process and in the chemical industry. With global energy crisis,the exploration of new separation technology and devices, which reduce the energyconsumption and investment, has become an inevitable trend in chemical industry.As an alternative to conventional distillation, DWC (fully thermally coupleddistillation column) can reduce investment cost and operation cost at the same timeand achieve energy saving up to thirty percent. However, the industrial application ofthe DWC has been limited, and the reasons for this are complexity of its structure andmore degrees of freedom. There have already been several investigations centered oncontrol or design of dividing-wall column, and operability of DWC, which is closelyrelated to either the design or control of dividing wall column, has become a new hotresearch field.In the present work, the processes of DWCs for separating three-componentmixtures are numerically simulated. Four columns based on four differentcompositions were designed by rigorous simulation to investigate effect of vapor splitratio decision in design on operability for DWC. By the results of our simulations, wefirst show how the plot of rvvs TAC changes if the rlis changed, then the optimalvalue of the liquid split ratio is plotted against the variation of the vapor split ratio. Wealso show the sensitivity of the DWC operation to its vapor split ratio, the extent towhich the split ratio could be feasible for the DWC to fulfill the separation task. Byexamining the rv-TAC relationships for different feed compositions, the flexibility ofa DWC over feed composition change is investigated, and the decision on the rvforuncertain feed composition is discussed. Economical behavior of four divided wallcolumns in case of changes in feed composition are demonstrated as wellThe research in this manuscript can provide theoretical guidance for developmentand application of dividing wall column in our country, and also enrich the thermalcoupling theory and at the same time provides a new way for energy saving.