Abstract: With increasingly stringent emission standards (30mg/Nm3) for cement plants, more and more electric precipitators used before the cooler fan have been transformed into bag filters in China. To protect the bag filter, a stable and reliable cooling device is needed to cool the high temperature cooler waste gas in case of troubleshooting of the waste heat boiler. And cooler spraying system has been widely used in transforming electric precipitator into bag filter projects, with the characteristics of lower investment and operation cost. And it can realize constant, rapid and accurate control of the waste gas temperature, which can protect the bag filter effectively .