Design Of Rectisol Process For Feed Gas With Low-pressure And Hydrocarbon Components

Rectisol process plays an important role in coal chemical purification.The process uses the characteristics of high selectivity and good solubility of methanol for acid gas at low temperature to selectively remove acid gas impurities such as CO₂,H₂S and COS from feed gas,which has the advantages of high purity and low energy consumption.The process is widely used in coal to methanol,coal to natural gas,ammonia and other processes.At the same time,the rectisol processes to fulfill the requirements of various feed-gas situations also has been widely employed.The feed gas involved in this paper belongs to a special feed gas.First,the feed pressure of the feed gas is 2.75Mpa,which is lower than that of the conventional feed gas at a pressure level of 3-8Mpa,which is not conducive to the absorption of CO₂.In addition,the feed gas also contains organic hydrocarbons and benzene and other impurities compared with common row gas.If not removed in advance,it will pollute the poor methanol,and the enrichment of impurities in the system will affect the absorption efficiency of low-temperature methanol.According to the specific process characteristics of the feed gas,two sets of rectisol processes are proposed as process I and process?on the basis of Linde one-step rectisol process.Process I adopts traditional rectisol flowsheet containing 5 towers with extraction section employed.Process?adopts rectisol flowsheet containing 6 towers with extraction section employed.First of all,with the help of chemical simulation software Aspen Plus,the process is based on PSRK property method and employs the appropriate unit module;secondly,the process is optimized the parameters of each tower by using sensitivity analysis tools and design regulations to reduce the production cost on the premise of meeting the process requirements;Thirdly,the process is designed the heat exchange network matching design of the two sets of processes by using pinch analysis method to obtain the reasonable heat exchange network matching scheme;finally,we simulate the whole process of the two processes,and analyze the purification capacity and energy consumption of the two processes.In this paper,two sets of rectisol process are proposed for low-pressured feed gas containing hydrocarbon components.Through simulation analysis,the best purification scheme is established,which provides both a reasonable theoretical basis for practical industrial application and a reference for the purification of similar feed gas,which has a good application prospect.