Gas treating alternatives for LNG plants
摘要
This paper covers the various gas treating processes available for treating sour natural gas to specifications required for LNG production. The LNG product specification requires that the total sulfur level be less than 30--40 ppmv, the CO{sub 2} level be less than 50 ppmv and the water level be less than 100 ppmv to prevent freezing problems in the LNG cryogenic column. A wide variety of natural gas compositions are encountered in the various fields and the gas treating process selection is dependent on the type of impurities present in the gas, namely, levels of H{sub 2}S, CO{sub 2}, mercaptans and other organic sulfur compounds. This paper discusses the implications various components in the feed to the LNG plant can have on process selection, and the various treating processes that are available to condition the gas. Process selection criteria, design and operating philosophies are discussed. An economic comparison for two treating schemes is provided.