The Study On Simulation And Revamp Of The Rectisol Process

Rectisol process was developed in the 1950s, and is mainly used for the sour gas purification. The solubility of acid gas in methanol is quite large at low temperature. According to this physical property of methanol, Rectisol process uses methanol as solvent to remove acid gas from feed gas. It also produces a concentrated H2S stream as Claus plant feed for sulphur production and CO2 offgas essentially free of H2S. Comparied with other purification methods, Rectisol process can produce high-purity gases by absorbing a variety of impurities. Moreover, Rectisol process has the advantages of high selectivity and low energy consumption, which is a widely used purification method.Methanol, as an important carbon-based chemical product, has been widely used in the production of methanol fuel, octane gasoline additive, methanol gasoline and other aspects. The main raw materials of methanol synthesis include natural gas, coal, heavy oil, etc., and 90 percent of foreign chemical plants use natural gas as raw material. However, the energy reserve of our country is that the resources of natural gas and oil are far less than coal. Therefore, using coal as raw material has become an important development direction and strategy of methanol synthesis industry.Due to the aging of the equipment and the changing of conditions in actual production, a variety of Rectisol processes are faced with problems of revamp and optimization. This work is involved to the revamp of the Rectisol process aiming at increasing the production by 30 percent. The whole Rectisol process of a coal-to-methanol plant is simulated by the common chemical simulation software Aspen Plus. Based on the strong simulation function and integrated physical property database of Aspen Plus, the whole process simulation is completed using PSRK physical property, and the simulation result and design data meet well. On this basis, the revamped schemes are proposed as follows:a new stripper is added to regenerate the rich methanol and reduce the temperature of poor methanol, which can increase the absorption capacity of H2S and CO2 largely. Meanwhile, semi-poor methanol solution cycle is established to reduce the amount of methanol into heat regeneration tower. In this way, it also reduces the amount of chilling consumption, as well as the heat load of heat regeneration tower and methanol and water separation tower. The revamping scheme can meet the goal of increasing production by 30 percent, and the results of key streams can also meet the technical index. Thus, the revamping process has expanded the production capacity of the original process.By using the original equipments mostly, this revamping scheme costs low investment and is easy to operate. The revamped scheme proposed in this paper can meet the requirements of the plant. This study can provide theoretical guidance for the technical revamp of the plant.