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Sour Gas: Gas containing undesirable quantities of hydrogen sulfide, mercaptans and/or carbon dioxide.

Sweet Gas: Gas which has no more than the maximum sulfur content defined by:

Absorption: A separation process involving the transfer of a substance from a gaseous phase to a liquid phase through the phase boundary.

Acid Gases: Impurities in a gas stream usually consisting of CO2, H2S, COS, RSH, and SO2. Most common in natural gas are CO2, H2S and COS.

Acid Gas Loading: The amount of acid gas, on a molar or volumetric basis, that will be picked up by a solvent.

Adsorption: The process by which gaseous components adhere to solids because of their molecular attraction to the solid surface.

Alkanolamine: An organic nitrogen bearing compound related to ammonia having at least one, if not two or three of its hydrogen atoms substituted with at least one, if not two or three linear or branched alkanol groups where only one or two could also be substituted with a linear or branched

alkyl group ( i.e. methyldiethanolamine MDEA ).

Claus Process: The process in which one third of the H2S is burned to SO2 which is then reacted with the remaining H2S to produce elemental sulfur.

Doctor Sweet: Describes a hydrocarbon stream which has had mercaptans removed to a level that it passes the Doctor Test (GPA-1138).

Mercaptan: Any of a homologous series of compounds of the general formula RSH. All of the materials possess a foul odor, e.g. methyl mercaptan.

Physical Solvent: A liquid capable of absorbing selected gas components by solubility alone without associated chemical reactions.

ppmv: A volume concentration of a species in a bulk fluid measured in parts per million.

Selective Treating: Preferential removal of one acid gas component, leaving at least some of the other acid gas components in the treated stream.

TGCU (Tail Gas Clean up Unit): a process unit that takes tail gas from a SRU and removes additional sulfur .

Threshold Limit Value: The amount of a contaminant to which a person can have repeated exposure for an eight hour day without adverse effects.

Natural Gas Pipeline Specifications

// Types of Contaminants

  • Ammonia (NH3)
  • Hydrogen sulfide (H2S)
  • Hydrogen cyanide (HCN)
  • Carbon dioxide (CO2)
  • Carbonyl sulfide (COS)
  • Carbon disulfide (CS2)
  • Mercaptans (RSH)
  • Nitrogen (N2)
  • Water (H2O)
  • Sulfur dioxide (SO2)
  • Elemental sulfur
  • Mercury and arsenic
  • Oxygen