A power plant in India will use a high-rate clarification and thickening process to treat cooling tower makeup water.

Siemens Industry Inc.'s Water Technologies Business Unit in Hoffman Estates, Ill., will provide cooling tower makeup water treatment equipment to a power plant in India. The order for Torrent Power Ltd.’s 382.5 MW gas-based combined-cycle power plant in India's Surat, Gujarat district, includes two Contrafast concentric systems. The systems will treat water from the Tapi River and produce up to 4 million gal/day of cooling tower makeup water. The system, slated for a September 2012 commissioning, is part of a capacity expansion at the power plant.

Power plants need a consistent, reliable source of water for cooling tower makeup In many cases, cooling tower makeup water must be treated for suspended solids reduction or hardness reduction. With properly treated water, the potential for scaling in the cooling tower is reduced, which then reduces cooling-circuit cleaning requirements, extends the life of the cooling equipment, and reduces the cooling tower blowdown flow to the environment.

The Siemens Contrafast concentric system is a high-rate clarification and thickening process that consists of a solids contact reaction chamber, clarifier with tube settler and gravity thickener in a single tank. The entire process is contained in a single, unitized steel basin to simplify installation.

According to Siemens, Torrent Power, headquartered in Ahmedabad, Gujarat district, chose the Contrafast system mainly because of its integral solids thickener and minimal footprint. The design allows up to an 80 percent smaller footprint compared to some other conventional clarification systems, and the process enhances suspended solids’ removal, lime softening and heavy metals removal.