Natural gas is the main source of energy. Liquefied natural gas or LNG is a natural gas that has been converted to a liquid form to facilitate storage or transport by cooling natural gas to about -162 ° C. It is then stored at atmospheric pressure. Liquefied natural gas occupies about six hundredths of the volume of natural gas in the gaseous state. It is odorless, colorless, non-toxic and non-corrosive. Because it is easy to transport, LNG can be used to save natural gas bearings for which the construction of pipelines is uneconomical.
Liquefaction of natural gas into LNG requires cooling of natural gas until it becomes liquid. These processes involve treating the gas prior to liquefaction, treatment and control of impurities and liquid hydrocarbons, as well as the storage and handling of refrigerants used to cool natural gas to the liquid state. Liquefaction also has the advantage of removing oxygen, carbon dioxide, sulfur and water from natural gas, resulting in LNG, which is almost pure methane.
The refrigerants used in the LNG process usually consist of a combination of the following light hydrocarbons: methane, ethane, ethylene, propane , butane and isopentane. Nitrogen is also a common refrigerant component.
The liquefaction process requires significant refrigeration compression systems that include large centrifugal compressors typically powered by gas turbines, steam turbines, or large electric motors.
When LNG reaches its destination, it returns to the gasification facility. LNG (methane) vapor mixed with air is not explosive in an uncontaminated environment. In the event of a large LNG release, a fire could occur, but only when there is a concentration (5 to 15%) of the LNG pair in the air and a source of ignition.