燃煤工业锅炉可吸入颗粒物的排放特征

Emission Characteristics of PM_(10) from Coal-Fired Industrial Boiler

利用基于荷电低压捕集器（ELPI）的颗粒物排放稀释采样系统,在8个燃煤工业锅炉的除尘器进、出口进行了烟气可吸入颗粒物（PM10）和细微颗粒物（PM2.5）的现场测试.粒径分布结果表明,在所测粒径范围（0.03～10μm）内,燃煤工业锅炉产生和排放PM10的粒数浓度和质量浓度均出现1个峰值,峰值粒径大约在0.12～0.20μm范围内.PM2.5中碳组分和硫酸盐的含量较高,其中有机碳（OC）和元素碳（EC）含量分别为3.7%～21.4%和4.2%～24.6%,硫酸盐含量则在1.5%～55.2%之间.在无控条件下,燃用原煤的层燃炉的PM10和PM2.5排放因子分别为0.13～0.65 kg.t-1和0.08～0.49 kg.t-1,燃用型煤的链条炉分别为0.24 kg.t-1和0.22 kg.t-1,而循环流化床的PM2.5排放因子为1.14 kg.t-1,明显高于链条炉.由于耗煤量大,同时现有除尘设备的效率较低,燃煤工业锅炉可能成为我国最重要的PM10排放源,是今后重点控制的对象.

Through ELPI （electrical low-pressure impactor） based dilution sampling system, the emission characteristics of PM10 and PM2.5 was studied experimentally at the inlet and outlet of dust catchers at eight different coal-fired industrial boilers. Results showed that a peak existed at around 0.12-0.20 μm of particle size for both number size distribution and mass size distribution of PM10 emitted from most of the boilers. Chemical composition analysis indicated that PM2.5 was largely composed of organic carbon, elementary carbon, and sulfate, with mass fraction of 3.7 % -21.4 %, 4.2 % -24.6 %, and 1.5 % -55.2 % respectively. Emission factors of PM10 and PM2.5 measured were 0.13-0.65 kg· t- 1 and 0.08-0.49 kg·t-1 respectively for grate boiler using raw coal, and 0.24 kg·t-1 and 0.22kg·t-1 for chain-grate boiler using briquette. In comparison, the PM2.5 emission factor of fluidized bed boiler is 1.14kg·t-1 , much her than that of grate boiler. Due to high coal consumption and low efficiency of dust separator, coal-fired industrial boiler may become the most important source of PM10, and should be preferentially controlled in China.