燃煤电厂煤粉炉及CFB锅炉PM2.5产生及排放特性的现场实验研究

摘要

A dilution sampling method was used to collect PM2.5 before and after COHPACs (compact hybrid particulate collector) generated by a pulverized coal boiler (boiler A) and a circulating fluidized bed boiler (boiler B) with installed capacities of 220 MW and 300 MW, respectively. Particle size distributions (PSDs) of PM2.5 were analyzed by ELPI; individual microstructures of PM2.5 were analyzed by SEM (scanning electron microscopy);concentrations of minor elements in PM2.5 were analyzed by EDX (energy-dispersive X-ray analysis) and concentrations of trace elements in PM2.5 were analyzed by ICP-OES (inductively coupled plasma optical emission spectroscopy). The distribution characteristics of number and mass concentration of PM2.5 at the corresponding sampling positions of two boilers were different. Most of the PM2.5 before and after COHPAC-A (boiler A’s) were spherical;most of the PM2.5 before and after COHPAC-B (boiler B’s) were irregular in shape;the PM2.5 after COHPAC-A were with relatively uneven surface, PM2.5 microstructures before and after COHPAC-B were similar;mass fraction size distributions of Si, Al, Fe, Ca and Mg in PM2.5 before and after the two COHPACs were similar;mass fraction size distributions of As, Cd and Se in PM2.5 before and after the two COHPACs increased with decreasing size;mass fraction size distributions of As and Se in submicron PM2.5 after COHPAC-A were higher than those before COHPAC-A, but mass fraction size distributions of As and Se in PM2.5 before and after COHPAC-B were correspondingly nearly the same.%采用稀释采样方法对一台220 MW煤粉炉(锅炉A)及一台300 MW的CFB锅炉(锅炉B)电袋复合式除尘器前后PM2.5进行现场采样。通过ELPI测定PM2.5的粒径分布；采用SEM分析PM2.5的显微结构；采用EDX及ICP-OES分别对分级PM2.5中次量及痕量元素含量进行了检测。结果表明，锅炉A和B除尘前后对应的PM2.5粒数及质量浓度分布均不同；锅炉A和B产生的PM2.5分别以较为光滑球形和不规则形状为主，锅炉A除尘后PM2.5呈表面粗糙球形，锅炉B除尘后PM2.5单颗粒形貌特征不变；锅炉A和锅炉B产生的PM2.5除尘前后在各粒径段中Si、Al、Fe、Ca和Mg含量基本一致，As、Cd和Se含量随着粒径的减小而增大；除尘后锅炉A产生PM2.5中As和Se含量增加，且在亚微米PM2.5中As和Se含量的增加更明显，锅炉B除尘后PM2.5中As和Se含量基本不变。