Gaseous Feed Stocks from Natural Gas

Ethane, LPG and condensate are extracted in large amounts in the processing of natural gas. When gas comes to the surface it contains many components which need to be extracted before it can 

Liquid products produced from gas come under a variety of names. Natural gas liquid (NGL) is a generic term for all condensed products. The C5+ fraction (boiling 30°C) is often referred to as condensate, or sometimes, especially in the US, natural gasoline. The Cj and C4 fraction is liquefied petroleum gas (LPG). 

When considering the higher hydrocarbons present in natural gas it is probably best to recall that a continuum exists in oil and gas reservoirs from almost pure methane to heavy petroleum oils and waxes. In general, hydrocarbon deposits do not span to the extremes higher hydrocarbon free natural gas is not commonly accounted although there are some very large natural gas deposits which comprise almost entirely methane . Thus many oil reserves have considerable quantities of associated gas and most gas reserves have associated with them light oil (condensate) deposits. 

Removal of NGLs is performed sequentially with the highest boiling fractions being removed first. 

Often the gas pressure is sufficient to use a turbo-expander which cools the gas to below 0 C and causes further condensation of hydrocarbon liquids. Because the gas stream also contains water, gas hydrate and ice formation can be a problem. This is prevented by the addition of an additive such as methanol. Following the removal of condensate, the gas stream is dried and if necessary treated further to remove acid gases such as hydrogen sulphide and carbon dioxide. 

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