某200 MW燃煤发电机组颗粒物生成与排放特性

摘要

利用低压撞击器系统对某200 MW燃煤发电机组布袋除尘器入口和出口及石灰石-石膏湿法脱硫(WFGD)塔出口的颗粒物进行现场采样，分析了机组的颗粒物粒径分布情况、布袋除尘器的除尘特性，以及 WFGD系统对颗粒物排放特性的影响.结果表明：煤粉燃烧生成的颗粒物呈明显的双模态粒径分布，超细颗粒物 PM0．2在 PM10中占比重较小，仅为0．64％；布袋除尘器对PM10颗粒物的脱除效率为99．98％，但对超细颗粒物 PM0．2的脱除效率偏低，约为99．88％，这是由于布袋除尘器工作过程中小粒径颗粒更易穿透布袋及其表面的灰层；WFGD系统对粒径超过2．5μm的颗粒物具有脱除作用，但在WFGD系统运行中由于石膏浆液携带以及超细颗粒物的团聚长大，会使粒径在0．5μm左右的颗粒物质量浓度大幅增加.%By applying low-pressure impactor system,particulate matter (PM)measurements were per-formed at the inlet and outlet of the fabric filter (FF)and the outlet of limestone-gypsum wet flue gas des-ulfurization (WFGD)tower in a 220 MW pulverized coal fired power plant unit.The PM formation charac-teristics,the FF's dust removal characteristics and the influence of the WFGD system on PM emission were discussed.The results show that,the PMs were of bimodal size distribution and the PM0.2 accounted for on-ly 0.64% of the PM10 .The FF had a high removal efficiency (99.98%)to the total fly ash particles.How-ever,the removal efficiency of PM0.2 was only 99.88%,as the PMs with smaller particle size penetrate the filter and deposited on the surface more easily.The concentration of PMs with diameter larger than 2.5μm reduced in the WFGD system while the PMs with diameter less than 2.5μm (particularly around 0.5μm) increased due to the ultrafine PM aggregation as well as new PM formation from gypsum slurry entrain-ment.