Natural Gas Liquefaction Process for Small-scale LNG Project

In the field of natural gas liquefaction, the small-scale natural gas liquefier has been attracting more and more attentions home and abroad, thanks to its small volume, mobile transportation, easy start-up and shut-down, as well as skid-mounted package. A study was made to choose the optimum liquefaction process to improve the economy of small-scale liquefied natural gas (LNG) plant. The same conditions are used to evaluate three types of liquefaction process which include propane pre-cooling mixed refrigerant cycle, nitrogen-methane expander cycle and SP-MRC (Mixed Refrigerant Cycle in Skid-mounted Package) put forward by authors. The result of comparison indicates that SP-MRC is suitable for mostly small-scale LNG plants in skid-mounted package due to its reduced equipment list and acceptable power consumption. The new SP-MRC adopts the technology of integral incorporated cascade which combines heavy and light hydrocarbons. It can reduce the quantity and volume of compressors and heat exchangers ensuring higher liquefaction rate and lower specific power consumption.