Liquefaction of LNG takes place in “LNG processing Trains”. Each “Train” consists of the “Treatment Step”, Removal of the condensates by fractional distillation, followed by liquefaction of the natural gas. In some LNG trains, where the volumes allow and markets exist, an intermediate cooling and distillation step to remove LPG’s (propane and butane) is undertaken. This is not currently done at Oman LNG.
The liquefaction step is driven by two large turbine driven compressors, which through a series of compression and adiabatic and non-adiabatic cooling steps cools the gas to -162ºC where the gas turns into liquid.
Each LNG Train has a nominal capacity that is determined primarily by the size of the compressors. In the early days of LNG, trains were less than 1 million tons per annum (MTPA). At Oman LNG each of the three trains can produce over 3 MTPA.