Sulfur Deposit Removal and Control in a Power Plant Cooling Tower: a Case History from Cerro Prieto, Mexico`s Largest Geothermal Field

Abstract

Effective deposit control is necessary to achieve optimum cooling efficiency in all cooling systems. Evaporative cooling systems in some geothermal power plants experience an unusual form of fouling – the accumulation of hard elemental sulfur deposits in hot water distribution lines and spray nozzles, on the tower fill, and in the condenser. This paper describes field trials of a sulfur deposit dispersant conducted in two 400,000 gallon cooling systems associated with 25 MW power generation units at the Cerro Prieto IV Geothermal Power Plant (Mexico). A successful 28-day field trial demonstrated the ability of daily cleaner/dispersant treatments to remove and disperse existing sulfur deposits and biofouling deposits from a fouled, underperforming cooling system. A successful 3-month trial demonstrated the ability of regular cleaner/dispersant treatments to prevent sulfur deposit formation and improve cooling efficiency in a cooling tower which was mechanically cleaned prior to the trial. Plant operating data and trial monitoring data are presented, along with a discussion of the characteristics of the operating environment in the geothermal cooling water system which make these plants susceptible to this unique and persistent form of fouling.