关键词: 丙烷脱氢, 氢气回收, 过程模拟与优化, 热泵精馏, 变压吸附

Abstract: Propane dehydrogenation is one of the main processes for propylene production and its reaction gas components are complex, containing products from main reactions and by-product components such as CO2 and CO from side reactions. To obtain polymer grade propylene and purified hydrogen product with a purity of more than 99.90 mol/mol, the separation process of the reaction gas of propane dehydrogenation and the recovery of hydrogen from hydrogen-rich tail gas is modeled and simulated in the Aspen software. The process includes main modules such as MEA decarburization, compressed cryogenic separation, deethanization, propylene distillation and pressure swing adsorption. The CO2 contained in the reaction gas would affect the purity of the propylene product, and it is difficult to remove in the cryogenic process. Thus the CO2 is first removed by the MEA solvent absorption. The reaction gas after decarburization and dehydration enters the deethanizer and the propylene distillation unit, and the hydrogen-rich tail gas enters the pressure swing adsorption unit for further purification. In order to reasonably utilize the energy of the propylene distillation tower, the heat pump distillation process is adopted for the energy integration. Compared with conventional distillation, the energy consumption of propylene heat pump distillation is lower. Sensitivity analysis and optimization of process parameters for hydrogen recovery by pressure swing adsorption are carried out to improve economy and energy efficiency. For the two-bed four-step pressure swing adsorption process, the effects of adsorption pressure, adsorption time and purge ratio on the purity and recovery of hydrogen products are analyzed, and the optimal operating conditions are determined. The simulation results show propylene and hydrogen products meet the requirements. The energy consumption per unit product is 267.46 kg standard oil/t propylene product and 474.44 kg standard oil/t hydrogen product. It has a certain reference significance for the simulation of the actual propane dehydrogenation reaction gas separation process and energy consumption estimation.

Key words: propane dehydrogenation, hydrogen recovery, process simulation and optimization, heat pump distillation, pressure swing adsorption