The reduction in freshwater use also reduces the facility’s wastewater by the same amount, Nalco said.
The station uses both river and well water in its cooling system, but the source water contains high concentrations of silica, which can cause damaging buildup of sediment in the cooling system. Nalco’s 3D Trasar technology controls the cooling water chemistry with fluorescence-based monitoring and silica dispersant to prevent silica from accumulating, according to the Nalco website.
Nalco said that the deposit occurs when the recirculating water’s silica concentrations exceed 150 ppm and the temperature is less than 70°F (21°C). In NV Energy’s system, silica concentrations were about 230 ppm on average. The incoming water temperature was about 80°F (27°C) with a 20° temperature drop across the tower.
NV Energy also is using 3D Trasar boiler technology at its coal-fired North Valmy Station. The station’s steam turbines were experiencing deposits that reduced overall efficiency. The boiler system controls allow the station to generate the same amount of electricity while reducing fuel consumption by 87,000 tons of coal annually, reducing costs by $3.5 million per year, Nalco said.