Calpine Tackles Froth and Foam with Non-Contacting Radar

Emerson’s Cathy Ershen and Jim Elchook shared a case study on geothermal power generation. Their abstract:

H2S abatement may be required to meet local environmental regulations for a geothermal plant. At Calpine’s Geysers, a number of the operating power plants have Stretford H2S Abatement systems which is the primary abatement systems for surface condenser vent gases. We focus attention on the liquid level measurement technology in use in the Stretford system froth and balance tanks which were initially designed with “bubbler” level measurement systems, when the plants were constructed by Pacific Gas & Electric (PG&E) in the 1980’s.

Cathy opened sharing that plants are capable of generating up to 725 megawatts of green energy around the clock. The plant is a dry steam power plant where steam is produced directly from the geothermal reservoir to run the turbines that power the generator; no separation is necessary because wells only produce steam, making this a more simplified process.

She described the froth and balance tank application. The Stretford Solution is a combination of foam/froth, solids, and liquid, an aqueous solution which is extremely challenging to measure level. The tank is continuously agitated and lined. Since the tanks are open to the atmosphere and lined, top-down technology is needed. In the past, bubblers with DP level transmitters were used for the application and were inaccurate.

pulse-radar-measurementNon-contacting radar can eliminate this complexity for operators and maintenance. Based on the dielectric of the liquid being measured, the surface reflects the radar signal back to the transmitter to measure the distance to the liquid level. In this application the foam reflected some of the radar signal and the surface. The Rosemount Radar Master software has a double surface function which can determine the level at the surface and ignore the foam. With a guided wave radar device, the frequency of the radar signal is much lower so it will ignore the foam all together.

Non-contacting radar technology is accurate, reliable, repeatable and is configured with the complimentary Rosemount Radar Master software.

You can connect and interact with other level measurement experts in the Level track of the Emerson Exchange 365 community.

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