In processing of petroleum, the removal of propane and sometimes higher fractions.

Related Terms


The temperature at which a liquid boils. As the boiling temperature rises with an increase in pressure (see saturated vapor pressure), the boiling temperatures are usually given for atmospheric pressure. At this pressure, water boils at +100° C., butane at - 0.5° C., ammonia at - 33° C. and propane at - 43° C.


A paraffin hydrocarbon (C3H8) that is a gas at ordinary atmospheric conditions but easily liquefied under pressure.


A fractionating column in a gasoline plant for removal of propane and lighter components.


Liquefied Petroleum Gas - this group of products includes propane and butane which can be shipped separately or as a mixture.
The LPG gases are taken out of the raw oil during refining, or from natural gas separation. LPG gases are defined as propane, butane and a mixture of these. Large atmospheric pressure gas carriers carry most of the LPG transported at sea. However, some LPG is transported with intermediate pressure gas carriers. Fully pressurised gas carriers mainly handle coastal trade. LPG can be cooled with water, and most LPG carriers have direct cargo cooling plants that condense the gas against water.
The sea transport of LPG is mainly from The Persian Gulf to Japan and Korea. It is also from the north- west Europe to USA, and from the western Mediterranean to USA and Northwest Europe.
LPG is utilised for energy purposes and in the petro-chemical industry


This is the abbreviation for Natural Gas Liquids. These are the liquid components found in association with natural gas. Ethane, propane, butane, pentane and pentanes-plus are typical NGLs.
The gas separates by refining raw oil. The composition of wet gas varies from oil field to oil filed. The wet gas consists of Ethane, LPG, Pentane and heavier fractions of hydrocarbons or a mixture of these. Atmospheric pressure gas carriers and semi-pressurised gas carriers carry the most of the wet gas.

Ethane can only be transported by semi-pressurised gas carriers, which have direct cascade cooling plants and are allowed to carry cargo down to -104 deg C. This is because Ethane has a boiling point at atmospheric pressure of -89 deg C. This will create too high condense pressure if using water as cooling medium. The cargo is condensed against Freon R22 or another cooling medium with boiling point at atmospheric pressure lower than -20 deg C.

Wet gas is transported from the Persian Gulf to the East, Europe to USA and some within Europe. There is also some transport of wet gas in the Caribbean to South America.

NGL is utilised for energy purposes and in the petro-chemical industry.

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