Natural Gas Industry Expander Gas Plant - Application Note

The Expander Gas Plant is an important step in the processing of raw natural gas into commercial products such as pipeline-quality natural gas and natural gas liquids (NGL). The Expander Gas Plant is designed to extract ethane and heavier constituents of the raw natural gas through a cryogenic distillation process. The operator of the gas plant is typically billed for the "shrinkage" across the unit which is the BTU decrease between the raw gas feed and the residue gas.

The first gas chromatograph analysis point is the feed to the gas plant to determine the composition of the gases and the amount of BTU’s entering the plant. In addition to calculating the BTU, the analyzer also calculates the specific gravity, and gallons per thousand cubic feet of gas of compressible liquids.