The determination of water vapor (water dew point) is crucial in the processing, custody transfer and transport of natural gas. High levels of water vapor in a natural gas stream can lead to a number of problems which include the formation of hydrates and the contribution to corrosion of plant and equipment. Furthermore, water vapor present in natural gas streams affects the overall quality of the gas, making the measurement of water vapor in natural gas an important requirement to producers, suppliers and end users in the industry.
Equally important is the need to determine the hydrocarbon dew point temperature in a natural gas sales pipeline network. The formation of hydrocarbon liquids (condensate) due to the presence of heavier hydrocarbons in the natural gas can lead to increase pressure drops in the pipeline system, flooding and safety hazards associated with liquids such as hot spots on compressor turbine blades.
There are a number of ways of determining the water vapor concentration in natural gas, and the various suppliers of the analytical technologies utilized have spent many years developing, improving and optimizing their analyzers to provide accurate, reliable and robust solutions for their customers.
AMETEK Process Instruments has been in the business of moisture analysis and hydrocarbon dew point determination for the natural gas industry for nearly four decades, and has pioneered the development of many on-line devices used for the detection of water vapor in many industrial applications. This paper presents a brief review of the most common methods and technologies used for the determination of water vapor, water and hydrocarbon dew point temperatures in natural gas applications.