Design Of The Refrigerated Methanol Process With Benzene-containing Feed Gas

In ammonia and methanol synthetic industry, the feed gas needs to be treated to get purified gas while exclude impurities, such as carbon and sulfide compounds. Purified gas should satisfy process requirements.Refrigerated methanol process is widely used in the purification area to remove impurities like H2S, COS, RSH, CO2, NH3, NO, etc, as well as recycle H2, CO, CH4and absorbent (methanol). The process should be modified when treating different feed gas. When it comes to benzene, which can form azeotrope with methanol and water, the process turns to be more complicated. The simulation of the purification process of benzene-containing but sulfur-free feed gas by general simulator is rarely reported. Therefore, it’s meaningful to do research in the field of separating impurities, which can form aerotrope with substances in the system, from feed gas, and designing separation process. Based on these work, the application of refrigerated methanol process can be widened. By using general simulator, the design work would be greatly simplified and the calculation time would be shortened.Benzene-containing feed gas without sulfide of a certain plant was given. Separation method was analyzed and chosen to separate azeotrope. A new chemical process was developed based on the traditional refrigerated methanol process. PSRK property method was chosen to calculate the simulation after being checked to be the most accurate.By using general simulator, main distillation towers were simulated. Operation parameters such as column number, reflux ratio were designed under the separation and process requirements. The designed process was optimized based on the simulation results. Then, simulation of the whole process was completed. Pinch technology was applied to analyze the heat exchanger network (HEN). Energy were saved after the retrofit, the total annual cost turned to be smaller. The new process was simple and can be applied with complicated feed gas.