Simulation And Optimization Of Rectisol Process

The Rectisol process using low-temperature methanol as an absorbent, removing acidgases selectively such as H2S, CO2in the raw material gas, is a highly efficient gas purificationand separation technology. Operated at low temperature and high pressure, high purificationand goodselectivity can be gained.The paper introduced the domestic and foreign developing situations, the processprinciple, the processes, duties and characteristics of the rectisol. The simulation toolPRO/Ⅱ was introduced briefly; PRO/Ⅱ is widely used all over the world now, because it isversatile and powerful.Depending on exact models and scientific calculation methods, PRO/Ⅱcan simulate the process flow strictly as well as optimize parameters of design and operation.In the paper, the mathematical model of the key equipments in Rectisol process wereestablished, the NRTL equation of state was chosen to describe the vapor-liquid equilibrium ofthe system, and the key equipments and the whole Rectisol process were simulated by PRO/Ⅱsimulation software. The simulation results of the key streams’ composition, temperature andflowrate, showed good agreement with the actual value. In the key equipments, thedistribution of temperature and the composition was reasonable. There is only a little deviationbetween simulation and the real process.This paper focused on the study of the reabsorber simulation results, examined andanalyzed the impact of factors such as the flowrate、temperature and diversion of methanol,carried out sensitivity analysis. The results were: in order to meet the separate indicators, theliquid-gas ratio must be located [0.34804,0.42588]; the temperature of the methanol must beless than-48.85℃; And the diversion should be smaller than0.9427. And the optimizationanalysis of the reabsorber showed the best operating parameters, the overhead pressure of theC140, C130, C120must be greater than3190kPa,3210kPa,3240kPa. The optimal traynumber of C110, C120, C130, C140were7,8,19,16. When the temperature of methanol andthe mole rate of the CO2changed, the liquid-gas ratio should be appropriately changed to meetthe requirements.