静电除尘器螺旋线放电极失效分析

Failure analysis of discharge electrode spiral in electrostatic precipitator

对浙江某1000 MW机组燃煤锅炉电除尘器螺旋线断裂问题进行了采样和分析,包括宏观形貌、断口SEM形貌、断口能谱、金相和安装问题进行了分析,结果表明:螺旋线化学成分符合ASTMA959-11的技术要求,断口上覆盖的异物中S元素质量分数高达27.34%,螺旋线断裂的主要原因是运行环境中S元素高,次要原因是安装不规范。在此基础上,在燃煤含硫量低于2.5%的烟气下电除尘器螺旋线使用316L以上材料并改进安装要求后,在多个工程上应用后,未发生螺旋线断裂问题。

Electrostatic precipitator(ESP)is the main technology of coal-fired flue gas dust treatment.Spiral wire has the advantages of uniform current density and high operating voltage,and is the best discharge electrode applied in the final electric field.However,with the wide application of the low-low temperature ESP technology,the fracture failure of the helix occurs frequently under the low-temperature working condition.Sampling and analysis were conducted on the spiral line fracture of the electrostatic precipitator of a 1000 MW unit in Zhejiang Province,including macrosco-pic,fracture SEM,fracture energy spectrum,metallographic and installation problem analysis,the results show that the chemical composition of the spiral wire meets the technical requirements of ASTM A959-11,and the content of S element in the foreign objects covered on the fracture surface is as high as 27.34%.The main reason for the fracture of spiral wire is the high S element in the operating environment,and the secondary reason is that the installation is not standardized.On this basis,after using 316L or above materials and improving installation requirements for the spiral line of the electrostatic precipitator in flue gas with a sulfur content lower than 2.5%in coal combustion,it has been applied in multiple projects without any spiral line fracture problem.