Optimization Of Pump-around Heat Distribution Of Low Carbon Hydrocarbon Separation Column

In process industry, distillation column is one of the most important separation units and costs lots energy. Among all methods focusing on reducing energy consumption of distillation system, intermediate heat exchanger, including pump-around and mid-reboiler has being played a very important role.This paper devotes in distribution optimization of intermediate heat exchanger in a distillation column, where the maximum exergy output is taken as the objective function, and the location, heat duty and the temperature difference are considered as the independent variables, meanwhile the tray number and the product case are kept no change. Two factors εn and△Qf are suggested in this paper. The former is regarded as Energy Level Coefficient (ELC), the later is called as Duty Changing Coefficient (DUC). The study shows that the higher temperature difference, more duty and closer top location or lower bottom location can result in larger εn, and vice versa, and no relationship between△Qf and temperature difference, but△Qf depends on the location and duty of intermediate heat exchanger as well as the materials which is separated in the distillation unitThe research process is base on the complicated distillation column model. For the more accurately reflects the situation of the hydrocarbon separation, this paper selecting the BWRS EOS and use the secant solves the density roots of BWRS. The mass balance equations are solved by a tridiagonal matrix method and the energy balance equations are solved by the bubble-point method. Taking "n-butane and iso-pentane" as an example, comparing the calculation results of column model with the simulation results of Aspen, the results are basically consistent.Eventually this paper gives a general method for the optimization of pump-around heat distribution of hydrocarbon separation column by integrate the complicated distillation column model and genetic algorithm (GA).