Abstract: Taking the depropanization unit in a gas separation process with a processing capacity of 160 kt/a as the research object, the coupling of Aspen Plus steady-state model and genetic algorithm is realized by using the interface function of Python, and then the operation parameters of depropanization unit are optimized. Under the condition of meeting the product purity requirements, the original single-tower depropanization process was replaced by the double-tower depropanization process.The operation cost of the doubledepropanizer was taken as the objective function. The hot water consumption of the high-pressure depropanizer and the steam consumption of the low-pressure depropanizer were taken as the decision variables to optimize the operation parameters of the depropanization unit. The results show that when the plates quantity of high-pressure and low-pressure depropanizer is 68 and 80, the feeding plate number is 19 and 36, and the reflux ratio is 3.0 and 4.6, respectively, the hot water load of the high-pressure depropanizer of the gas fractionation unit is reduced by 36%, and the steam load of the low-pressure depropanizer is reduced by 19%.The annual operating cost of the unit is reduced from 5.54 million yuan per year to 3.35 million yuan per year.

Key words: gas separation process, depropanization tower, steady state simulation, genetic algorithm, Aspen Plus simulation