Studies On The Revamped Process Of Rectisol And Its H₂S Cryogenic Recovery Units

Determined by China's energy structure,coal chemical engineering occupies a large proportion in the primary energy applications.The gasification technology of coal plays a fairly important role in coal chemical industry.The syngas after coal gasified contains a plenty of acid gases which need to be removed before being used.Currently,rectisol process is basicly used for acid gas purification in the fields of ammonia synthesis and methanol synthesis.Adopting low-temperatured methanol as solvent to purify syngas,rectisol process has been widely used owing to its merits of high selectivity,high purification and low energy consumption.The first part of this work is to reform the rectisol unit in a plant attempt to solve its problems of high energy consumption and low recovery rate of CO₂ product.Rectisol process was simulated by using Aspen Plus with PSRK thermodynamic equation selected.To ensure the accuracy of the simulation of the whole process,sensitivity analysis tools were employed.Two schemes are put forward based on the revamped original process.In scheme?,the entry flow of rich-carbon methanol and rich-sulfur methanol into the reabsorption column were changed,whereas in scheme?,a new flashing tank is added with the extraction of liquid-phase derived from the third stage of reabsorption column as its feed.By comparisons of the energy consumption and CO₂ recovery rates,scheme?is preferable one,which decreases the energy consumption by 11.2%and increases the recovery rate of CO₂ product from 46.6%to 66.7%.The second part of this work is to develop a cryogenic H₂S recovery process coupled with rectisol where a booster expansion turbine is added to refrigerate and recover energy.During the simulation process,the distribution for different components in column,unit consumption and influence of expansion ratio on product flow and product concentration are analyzed in details,with 200kmol/h raw gas as feed.Eventually,when the distribution rate of the expansion is 0.35,the process operates at an optimal condition with the concentration of H₂S and the unit consumption of H₂S reaching 99.9%and 212.180 kW·h/t respectively.To sum it up,the first work provides theoretical guidance for the plant reformation and the second work provides a new idea for H2S treatment in the fields of coal chemical industry.