燃煤锅炉可吸入颗粒物排放规律研究

应用基于空气动力学直径分级的低压撞击器(LPI)对4台燃煤锅炉除尘器前后飞灰颗粒进行13级采样,研究了不同除尘器入口和出口PM10的颗粒粒径排放规律及元素分布特性.结果表明,除尘器前后PM10质量粒径均呈双峰分布,其峰值分别在0.1 μm和2.36～3.95 μm附近.无论是文丘里水膜除尘器还是静电除尘器,粒径为0.1～1 μm左右的颗粒的除尘效率最低,最低效率值在50%～65%左右.除尘器对不同粒径颗粒的收集效率差别很大,对粒径为10 μm左右颗粒的收集效率为96%左右,而对亚微米颗粒的收集效率在62%-83%之间.PM10中各级氧化物组成表明较易气化元素,如s和Na等在小粒径颗粒上有明显富集趋势,而不易气化元素Si和Al等在大粒径颗粒上富集;这说明小粒径颗粒可能为气化-凝结机理形成,而比较粗的颗粒可能是通过煤焦和矿物质的破碎以及内部矿物质的聚合形成.

Experimental Study on Emission Characteristics of PM10 in Coal-Fired Boilers

Fly ash was sampled at the inlet and outlet of ash collectors in four different coal-fired utility boilers using 13-stage low pressure impactor (LPI). The mass distribution, emission characteristics and the composition at different size particle of PM10 were studied. The results show that PM10 of the four boilers have a similar himodal distribution, with two peaks formed around 0.1 microm and 2.36 - 3.95 microm, respectively. The lowest efficiency of ash collectors was between 50% - 65% when the particle sizes were around 0.1 - 1 microm, no matter Venturi water membrane dust collector or ESP was used. Ash collectors show different removal efficiencies to various particle sizes PM. The removal efficiency of ash collectors was about 96% around 10 microm, while under 1 microm it was between 62% - 83%. The chemical composition of the size-segregated ash showed that the element S and Na were obvious enrichment in finer ash, which is possibly formed via vaporization and subsequent condensation of inorganic matter. While the refractory oxides were the major composition in bigger size ash, which may be formed via char fragmentation, excluded mineral fragmentation and included mineral coalescence.