Case Study - Geothermal Power Generation – Guadeloupe

Challenge:

The Bouillante geothermal power plant located in Guadeloupe was experiencing severe fouling in the rotating filters due to algae growth, which led to pump failures and pipe leaks. This failure was due to suspended concrete particles not effectively being removed and remaining in suspension within the cooling water, which caused significant pipe erosion to occur. Furthermore corrosion in the copper alloy cooling jacket of the main condensers was occurring along with scaling in the seawater condenser contact zones. The different multiple sources of fouling resulted in significant restrictions in the cooling system’s water flow.

Treatment:

The plant used naturally produced geothermal steam at about 242°C from a depth of 350 meters. The seawater circuit providing cooling water was approximately 350 meters in length with the seawater cooled to below 40°C. The plant is located adjacent to a sensitive marine reserve leading them to run a trial test of ecofriendly Mexel. Due to the severity of the situation, they underwent the Mexel trials with a continuous dosage of 4 ppm. The tests showed that Mexel reduced metal loss on a monitored carbon steel ring to a negligible corrosion rate of 0.03 grams.

Results:

The Mexel treatment was successful in near elimination of the rotating filters’ biofouling and in removing the blockage that was causing pump failures. With the filters operating effectively, the previous piping erosion produced by the suspended concrete was eradicated. Furthermore there was a noticeable reduction in the main condenser’s corrosion and an improvement of 0.2 bars backpressure at the main condenser’s entry. The scaling in the seawater’s condensers was also fully eradicated. Mexel significantly reduced system maintenance and leaks, which contributed to improving Bouilante’s on-line availability from 60% to 99.4% within two years.