Natural gas is a kind of combustible gas that is buried under the ground. Its main component is methane (CH4).
There are four main types of natural gas:
Field Gas
Flammable gas explored from gas wells is called pure natural gas or field gas. Its main component is methane (CH4), which is about 90% or more. In addition, it also has small amount of ethane (C2H6), propane (C3H8), hydrogen sulfide (H2S), carbon monoxide (CO) and carbon dioxide (CO2) etc.
Condensate field gas
Condensate field gas refers to the natural gas that contains light hydrocarbon consisted of both C5 and hydrocarbons larger than C5 that can be condensed, but doesn’t contain heavy oil. In addition to plenty of methane (CH4), it also contains 2%-5% C5 and hydrocarbons larger than C5.
Oil associate gas
Oil associate gas refers to the gas that is explored out together with liquid petroleum, and is a by-product of oil production. Its main component is about 70%-80% methane, and some other alkanes such as CO2, H2, N2, etc.
Coal mine gas
Coal mine gas refers to the gas explored from coal mine pit. It is a by-product of coal mining. In fact it is a mixture of coalbed gas and air. Its main component is methane (CH4) and nitrogen (N2). In addition it also contains O2 and CO.
Only when the content of CH4 is more than 40%, coalbed gas can be used combustion gas.
In addition to conventional gas form in pipeline, natural gas can be changed into LNG and CNG through purification and other process.
LNG
When temperature drops to -1620C, natural gas changes from gas into liquid, known as liquefied natural gas (LNG).
LNG is colorless, tasteless, non-toxic and non-corrosive. Natural gas liquefaction is a low temperature process in which the gas is pressurized above 0.1MPa at a temperature not exceeding the critical temperature (82 degrees Celsius). The volume of LNG is about 1/600 of that of the same amount of natural gas, and is about 45% of the weight of the same volume of water. LNG’s calorific value is 52MMBtu/t.
CNG
Compressed natural gas (CNG) is the natural gas that is compressed (more than 3600 pounds/square inch) to 20-25MPa, and is dehydrated under high pressure and stored in container. Its component is the same as that in pipelines. CNG can be used as vehicle fuel.
UNE can provide customers with total solution and equipment from natural gas purification to the compression of CNG or cooling to liquid LNG, and has plenty of project experience.