Simulation And Case Oplimization Of Rectisol Process

Rectisol process is a physical absorption method which takes low temperature methanol as absorbent to purify the acidic components in syngas. At low temperature, the different solubilities of CO2, H2S, H2, CO and other gases in methanol are used to remove acid gas selectively and H2/CO are recycled. As a highly-efficient gases purification technology, rectisol process has been widely applied to many kinds of industries such as coal chemical industry, ammonia synthesis and so on.Based on Aspen Plus software platform, the thermodynamic properties of rectisol system was studied. The state method of PSRK state equation was determined in consideration of the simulation accuracy of different kinds of thermodynamic equations,. In order to solve the problems of large deviation of physical parameters such as the density of liquid phasecalculated using the default Aspen Plus properties, the property calculation route and built-in correlations were modified to realize the accurate calculation of thermodynamic properties for syngas and multi-component system of low temperature methanol in this paper.The rectisol process used in an industrial plant was simulated. The shifted gas-absorption column, unshifted gas absorption column, H2S concentration column, heat regenerator and methanol/water separation column were studied. The simulation results are identical to practical production data. The maximum deviation was les than 5% and the average deviation was 3%. Besides, the distribution of concentration for main components was analyzed,which is identical to actual situation of each column.In order to realize the flexible production strategies to meet the market demands, the load capacity of shifted gas absorption column and other major equipment were studied and the sensitivity analysis of operational conditions such as the content of sulfide was conducted. The ultimate values of operational parameters were determined when control standards were satisfied. In the case of production load was increased by 20%, limit factors were determined by hydraulic check and analysis. A scheme was proposed for increasing load by transforming the tray structure of H2S concentration column whose design allowance was the least.An accurate method of simulating rectisol process was proposed in this paper and the results obtained can ba used in the production as reference and direction.