Troubleshooting and Preventive Measures of WESP Spray Nozzle Faults in Coal-Fired Power Plants

In order to meet the ultra-low emission requirements for coal-fired power plants, the wet electro-static precipitator(WESP) is used in some regions of the country. As the key part of WESP, the spray nozzle will immediately endanger the WESP operation in case of fault, such as blockage and dropping down, two types of major faults in the spray nozzle operation. Taking the WESP of a 600-MW unit firstly installed in Guangdong Province for example, based on the analysis on the operation experience, series of the feasible and effective contingency countermeasures are proposed. For instance, before the spray nozzle installation, clean up the WESP spraying circulating water system thoroughly and equip the nozzle with fine filter to lower the contents of solid impurities as much as possible. During the operation, flush the front collecting plate sparge pipe more frequently with large volume of water and tune the self-cleaning filter running mode. During the unit startup phase, increase drain tank blowdown, and reduce the overflow water from the water circulating tank to the drain tank, etc. The practice shows that with these measures, the failure rate has been significantly dropped.