Laser-based gas sensors keep moisture out of pipelines

By Control Engineering Staff July 5, 2006

NASA -based gas analyzer technology is helping oil producers such as El Paso Natural Gas Co. (EPNG) track pipeline moisture and avoid expensive shut-ins.

Natural gas at the wellhead often contains contaminants, including water, that must be removed and the gas cleaned to pipeline quality before it can be delivered safely to high-pressure long-distance pipelines. Various processes are used to remove the water vapor. Moisture readings must accurate and reliable to prevent false data from leading to unwarranted and expensive shut-ins and/or passage of contaminated gas.

To avoid these possibilities and meet quality standards of pipeline gas, EPNG has installed a new laser-based sensor technology where each of its 16 major producers in its San Juan district joins the pipeline. The tunable diode laser (TDL)-based process developed at NASA’s Jet Propulsion Laboratory at Caltech is highly effective at detecting contaminants in natural gas. Manufactured by SpectraSensors Inc. , a developer and producer of optical-based gas sensors, the bread-box-sized gas analyzer provides non-contact measurement of moisture, carbon dioxide, and other corrosives in natural gas pipelines.

Each producer can monitor El Paso’s gas analyzer readings by capturing the electronic signal from El Paso’s unit using a SCADA system and viewing readings in the producer’s control room. The sensors monitor the quality of tens of millions of dollars of gas each day. The analyzer responds quickly and provides an accurate measurement that does not drift. It therefore can be used in a closed loop to control the blending of wet and dry gas and allow a producer to optimize costs by staying just within the tariff.

—Control Engineering Daily News Desk

Jeanine Katzel , senior editor