The Study On Revamp Of Rectisol Process After Adjusting The Feed Gas

The main steps of coal-to-methanol technology include coal gasification, transformation, purification of raw gas and methanol synthesis. The coal gasification means the transformation process of solid coal into gas. Except for the effective gases such as CO and H2, the raw gas still contains a certain quantity of acidic gases such as CO2and H2S after transformation. In order to recycle the effective gases, the acidic gas components of the raw material must be got rid of, by process of decarburization and desulfurization. There are several kinds of gas purification methodologies such as Rectisol, MEA, NHD, etc. The Rectisol which is a typical physical absorption method outstands itself than other methods especially in some large petrochemical plants. Currently, several sets of Rectisol device have been set up in ammonia, fertilizer or methanol plants in domestic.The absorbent is methanol at low temperature in Rectisol. Due to the different solubilities of gases in methanol, the acid gases are absorbed with other active gases retained, in this way purifies the feed gas successfully. The Rectisol process was developed originally by Linde and Lurgi companies overseas about60years ago, and20years later started in domestic. After years of research, some domestic universities and research institutions such as ZJU, DLUT, SRIPT, Sinopec Lanzhou design institute have made some achievements in this field.The feed gas adjusted in Rectisol process in one plant was analyzed in this paper. With the powerful function of the general simulation software, the appropriate property method was selected. Based on the simulation and study of original Rectisol device, main equipment units in process were optimized and designed to meet the separation and process requirements. The transformation schemes were proposed:cold ammonia supplied at the higher temperature place could solve the shortage problem of cold energy of the system. The method of vacuum desorption instead of stripping the nitrogen could improve the recovery rate of CO2, cancel the tail gas and make the process simple as well. These studies provide a basis for Rectisol device’s revamping for the plant.