Precooling strategies for efficient natural gas liquefaction

The invention of the propane precooled mixed refrigerant (C3MR) natural gas liquefaction process in 1970 brought about better efficiency and greater economies of scale than had previously been available to the young LNG industry. Splitting the refrigeration duty between two refrigerants allows each to be individually optimized; the first is used to precool the natural gas feed to a moderate temperature, and the second is used to liquefy and subcool the precooled gas to produce LNG. Due to these advantages, precooling is used in a majority of baseload LNG trains today. Various precooling refrigerants have been proposed in the LNG industry, such as propane, mixed refrigerant (MR), ammonia, ca