The process begins with the pre-treatment of a feedstock of natural gas entering the system to remove impurities such as H2S, CO2, H2O, mercury and higher-chained hydrocarbons.
Feedstock gas then enters the liquefaction unit where it is cooled to between -145 °C and -163 °C .
Although the type or number of heating cycles and/or refrigerants used may vary based on the technology, the basic process involves circulating the gas through aluminum tube coils and exposure to a compressed refrigerant.
As the refrigerant is vaporized, the heat transfer causes the gas in the coils to cool.
The LNG is then stored in a specialized double wall insulated tank at atmospheric pressure ready to be transported to its final destination.
Most domestic LNG is transported by land via truck/trailer designed for cryogenic temperatures.
These units consist of an internal steel or aluminum compartment and an external carbon or steel compartment with a vacuum system in between to reduce the amount of heat transfer.
Once on site, the LNG must be stored in vacuum insulated or flat bottom storage tanks.
When ready for distribution, the LNG enters a regasification facility where it is pumped into a vaporizer and heated back into gaseous form.
The gas then enters the pipeline distribution system and is delivered to the end-user.