Hydrocarbon dew point in fuel gas has become a recent concern for Saudi Aramco and Saudi Electricity Company (SEC). Together they operate more than 150 land based industrial and aeroderivative combustion gas turbines (CGTs) on natural gas produced in the Eastern Province of Saudi Arabia. Automated on-line hydrocarbon dew point monitoring conducted over the past two years has revealed wide variations in the hydrocarbon dew points of the fuel gas that supply these turbines. During winter months at some locations, hydrocarbon dew points are now known to rise to, and slightly above ambient gas temperatures. Daily variations in dew point temperature average about 12–14 °F (7–8 °C) in winter months with highs occuring in late morning hours. More dramatic changes (60 °F, 33 °C) were recorded and attributed to operational changes in two major gas plants. At a major power generation facility, hydrocarbon dew point data was referenced in time with inlet fuel temperature and inlet fuel pressure recorded from a turbine control system. This data reveals evidence that liquid hydrocarbon was entering the CGT fuel intake. Damage to hot gas path components from liquids in natural gas fuel has cost Saudi Aramco several million dollars over a 10 year period (1985–1995). The estimates are much higher now with expanded use of natural gas into the Central and Western Provinces of Saudi Arabia. The new sources of gas, new processing facilities and longer transmission distances all contribute to greater potential for liquids formation, while upgrades to higher firing temperatures also increases the sensitivity of some CGTs to liquids in the fuel. With dew point monitoring, we will be able to recommend the necessary fuel conditioning equipment and fuel preheating temperatures that will be needed to prevent costly distress to CGTs due to the passage of liquids in the fuel gas.

This content is only available via PDF.
You do not currently have access to this content.