Save energy and water with a system that generates boiler makeup water
By Chemical Engineering |
In boilers, silicates can volatilize with the generated steam and then form silicate glass on turbine blades, causing an imbalance. Therefore, the concentration of silicates in boiler circuits must be reduced to below 0.5 parts per million (ppm). The conventional method for treating boiler make-up water (BMW) includes ion exchange, or a combination of ion exchange and reverse osmosis. Now, an alternative, energy-efficient distillation-based process has been recently patented that not only completely eliminates silicates from BMW, but simultaneously recovers 97% of the blowdown that is normally discharged, thereby saving water. “The cost for producing boiler makeup water is about 5,000 times less expensive than alternatives,” says Ellis Young, the inventor of the process and president of Enthal-Pure LLC (Sedalia, Colo.; www.enthalpure.com). For a 500-MW power plant, the costs for producing water are reduced by $0.8–1.2 million/yr, and the water savings are about 10 million gal/yr due to reclaimed blowdown, he says.
In Enthal-Pure’s system (diagram), soft water enters the tube side of a condensate cooler (A) where it is warmed before mixing with hot blowdown in the shell side (B) and fed to a reboiler. Heating steam from the…