Content area
Full Text
Natural gas liquids (NGL) are a group of hydrocarbons, sometimes referred to as purity NGL, that includes ethane, propane, normal butane (n-butane), isobutane and natural gasoline (pentanes plus). NGL made their inroad into fuel markets in the 1910s, when the issue of gasoline loss while stored under normal conditions was addressed, leading to a way to bottle liquid gas.
NGL are produced predominantly in gas processing plants and, to a lesser extent, in refineries as homogeneous liquid blends ofpurity NGL. The NGL extracted from natural gas make up the so-called Y-grade NGL from which ethane, propane, n-butane, iso-butane and pentanes plus are separated by fractionation in a distillation unit. A subset ofNGL is liquid petroleum gas (LPG). LPG is a blend of propane, n-butane and i-butane.
All natural gases contain NGL. Although the quantity of liquids is not always great enough to be economically recovered, there are cases where NGL extraction is desired either to meet sales specifications (minimum and maximum high-heatingvalue requirements) or to produce transportable gas-i.e., a gas that can be piped without hydrocarbon condensation along the pipeline (dewpoint control).
This article provides an overview of technology for the recovery ofNGL, as well as a brief discussion on the economic reasons that justify the extraction of NGL from natural gas and provide the foundation for different processing facility configurations.
Fundamentals of NGL economics. NGL have a wide variety of applications, including feedstock for petrochemical production, as fuel for vehicles and as specialized fuels for space heating and cooking.
Among individual NGL, ethane has the largest share of NGL field production, followed by propane. Together, they make up 90% of the NGL barrel. Ethane is largely used to produce ethylene, the monomer used to produce polyethylene, ethylene oxide, ethylbenzene and dichloromethane, which are raw materials for the production of a wide variety of everyday objects.
Propane is the precursor of polypropylene, which is used to produce plastics, resins, rubbers and other materials. It is also used as a residential and commercial heating fuel, as a drying agent for crops, as a ripening agent for fruit, and so on.
N-Butane is used to produce butadiene, the key component in synthetic rubber. Butane is also used during winter as a fuel additive in motor gasoline. I-Butane...