Discussion on the purification process of natural gas based on GB 17820-2018

In recent years, with the increasing attention to the environmental protection in China, the commercial natural gas standards are more and more stringent, which is a severe challenge to the upgrading process of desulfurization unit in the natural gas purification plants. Therefore, the commercial natural gas standards in natural gas purification plant at home and abroad and the domestic natural gas quality were analyzed. The research status, advantages and disadvantages and future trends of three desulfurization processes which could decrease the H₂S and organic sulfur content in natural gas were also analyzed, including solvent desulfurization, molecular sieve refinement and carbonyl sulfur hydrolysis process. The results showed that to achieve stricter standard requirements of latest GB 17820-2018 Natural Gas, partial natural gas purification plants need technology upgrade or process improvement. Among the improvement measures, solvent upgrade should be first considered. If the organic sulfur content in feed gas is excessively high, the carbonyl sulfide hydrolysis technology can be used. If the mercaptan content in feed gas is excessively high, even if combining the solvent upgrade and COS hydrolysis technology, the purified gas still has the risk of exceeding standard. Then the technology of organic sulfur fine removal with molecular sieve can be used. Through selectively combining above three measures, the risk of purified gas exceeding standard can be basically eliminated. But according to the implementation and cooperation of above three technologies, further research in view of products, technologies and software need to be developed.