Acid gas
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Acid gas is natural gas or any other gas mixture which contains significant amounts of hydrogen sulfide (H2S), carbon dioxide (CO2), or similar contaminants.
Although the terms acid gas and sour gas are used interchangeably, strictly speaking, a sour gas is any gas that contains hydrogen sulfide in significant amounts. Whereas an acid gas is any gas that contains significant amounts of acidic gases such as carbon dioxide (CO2) or hydrogen sulfide. Thus, carbon dioxide by itself is an acid gas but it is not a sour gas.
Before a raw natural gas containing hydrogen sulfide and/or carbon dioxide can be used, the raw gas must be treated to remove those impurities to acceptable levels, commonly by an amine gas treating process.[1][2] The removed H2S is most often subsequently converted to by-product elemental sulfur in a Claus process. Carbon dioxide is removed by sorbent scrubbing.
Processes within oil refineries or natural gas processing plants that remove mercaptans and/or hydrogen sulfide are commonly referred to as sweetening processes because they results in products which no longer have the sour, foul odors of mercaptans and hydrogen sulfide.
Hydrogen sulfide is a toxic gas. It also places restrictions on the materials than can be used for piping and other equipment handling sour gas, as many metals are sensitive to sulfide stress cracking. Both carbon dioxide and hydrogen sulfide cause lower quality burning, and have strict tolerance limits in commercial gas sale.
[edit] See also
[edit] References
- ^ NaturalGas.org website page Processing Natural Gas
- ^ Energy Information Agency website page Natural Gas Processing: The Crucial Link Between Natural Gas Production and Its Transportation to Market
