Transformation Of Coal Methanol Claus Sulfur Recovery Process Exhaust System

With the increasing awareness of environmental protection, industrial sulfur emissions standards are more stringent. Coal-sulfur is mainly converted into hydrogen sulfide (H2S) and organic sulfur compounds during coal gasification. Sulfur was removed after the purification section and mostly converted into H2S. If H2S was not effectively treated, it will cause serious environmental and safety hazards. Therefore, the studies of sulfur recovery process have important practical significance to stable operation and to achieve exhaust emissions standards. Sulfur recovery unit was studied in China’s first IGCC system30t/a methanol plant. The main studies were as follows:(1) Claus sulfur recovery process and reaction mechanism were researched. The results show that many factors affect the production operations, such as:raw gas H2S content, impurity content, hydrocarbons, water gas, NH3, the proportion of H2S to SO2and the production load fluctuations. Use only the Claus process is difficult to ensure compliance Claus tail gas emissions. Therefore, Claus tail gas was treated by hydrogen and was absorbed by NHD organic solvent which has a good selectivity to H2S, and then the tail gas was burned into SO2, which can meet emissions standards. However, the production practice shows that this process is very complex, and still needs further improvement in energy consumption, equipment, operation stability, etc.(2) The reasons of effecting sulfur recovery unit steam system and exhaust system stable operation were analyzed. For sulfur recovery steam system, the high production load, big process gas flow, fast airspeed, gas entrained sulfur and separate tank gas over-temperature were considered the main reasons of pipeline blockage by sulfur. Measures of reducing byproduct steam pressure and adjusting valve recon reconstruction were taken to reduce the sulfur pipeline blockage and achieve safe operation. To the exhaust system, the low H2concentration hydrogenation reactor, sharing absorbent regeneration systems, unable treatment of sulfur acidic water and hydrogenation catalyst deactivation were the reasons of SO2long-term non-compliance. The improvement measures were taken by increasing H2concentration, solution regeneration system, acidic water system transformation and, N2temperature reconstruction.