Mon, January 28, 2008
Hydrocarbon dew points (HDPs) can indicate the quality of a natural gas stream. They can also be used to assess compliance with transportation tariffs. Accurate hydrocarbon dew points are crucial in accommodating the future introduction of liquefied natural gas (LNG) and marginal gas supplies into the natural gas transmission network.
The use of data from an on-site gas chromatograph (GC) is often faster and more convenient than using portable chilled mirror dew point testers. Unfortunately, the various methods used to calculate hydrocarbon dew points from GC analyses often produce inconsistent results across methods.
Previous research in 2001 identified the choice of characterization method as the largest source of potential error. Subsequent research sponsored by Gas Technology Institute (GTI), Pipeline Research Council International (PRCI) and the United States Department of Energy (DOE) in 2004 and early 2005 expanded the existing database to include experimental data on test gases.
This project completes the evaluation of analytical dew point determination methods begun earlier under the sponsorship of GTI and PRCI through the Federal Energy Regulatory Commission (FERC) funding mechanism.
Key Results Where an extended analysis of a natural gas stream is not available or fails to accurately predict the observed HDP of the stream, the Gauss-gamma characterization and the Soave-Redlich-Kwong (SRK) equation of state are recommended for predicting dew points from a C6+ analysis of the stream.