Published: December 2001
Natural gas liquids (NGLs) are the C2+ liquefied hydrocarbons that are recovered above ground in natural gas field facilities or in gas processing plants. The principle products are ethane, propane, isobutane, n-butane, and C5+ natural gasoline. Besides the growing demand for these NGLs, some natural gas is also extracted to obtain marketability of the gas by reducing its dew point to below pipeline specification. Some natural gases contain impurities that are removed in treaters.
Worldwide production of NGLs totaled over 246 million gallons daily in 2000. Due to increasing demand for environmentally clean burning fuels and increasing demand for petrochemicals such as ethylene and propylene, the demand for liquefied petroleum gas (propane and butane mixtures) is forecast to continue to grow at a faster rate than the demand for petroleum.
Developments in the turboexpansion process and new technology, acid gas re-injection for example, are reducing costs of NGL recovery from natural gas.
This report reviews the technology of gas treating and NGL recovery. Two of the most widely used recovery processes are evaluated: cryogenic turboexpansion, the leading process, and the refrigerated absorption process, an older process that ranks second in the U.S. and third worldwide in the production of NGLs.
We have also evaluated a generic fractionator that produces ethane, propane, isobutane, n-butane and C5+ natural gasoline from mixed NGLs produced by extraction plants. This report should provide a useful overview of the natural gas liquids extraction industry and process developments within the industry for people involved in the energy industry, professionals who research, development or plan investments in the natural gas industry as well as those professionals who manage, plan, operate or do design work of existing plants.