典型脱硫工艺对燃煤锅炉烟气颗粒物的影响

脱硫是燃煤锅炉的重要除污环节，为探究脱硫工艺对烟气颗粒物的影响，选取4台不同脱硫工艺（石灰石/石膏法、炉内喷钙法、氨法和双碱法）的燃煤锅炉，利用再悬浮采样法和稀释通道采样法分别采集脱硫前后烟气颗粒物样品，并测定颗粒物中的水溶性离子、无机元素和碳组分.结果表明，脱硫剂对烟气PM_2.5的组分构成产生影响，烟气经过石灰石/石膏法脱硫后，PM_2.5中的Ca由5.1%提高至24.8%；经过氨法脱硫后，PM_2.5中NH₄⁺的质量分数由0.8%提高到7.3%；双碱法脱硫则使烟气PM_2.5中Na由0.9%提高到1.7%.湿法和干法脱硫工艺的作用显著不同，湿法脱硫排放颗粒物的离子含量较高，经过石灰石/石膏法和氨法脱硫，PM_2.5中SO₄^2-的质量分数分别由2.0%和6.7%提高到9.6%和11.9%，Cl^-分别由0.4%和1.2%提高到3.8%和5.2%，而Cr、Pb、Cu、Ti和Mn等重金属经过湿法脱硫出现含量下降；相对湿法脱硫，干法脱硫燃煤锅炉排放的PM_2.5中富含Al、Si和Fe等地壳元素.湿法脱硫同样对碳组分产生影响，石灰石/石膏法和氨法脱硫后，烟气PM_2.5的元素碳EC质量分数分别从6.1%降至0.9%和从3.6%降至0.7%，但是有机碳OC的含量并没有下降.

Influence of Typical Desulfurization Process on Flue Gas Particulate Matter of Coal-fired Boilers

As flue gas desulfurization (FGD) was one of the most important purification processes of coal-fired boilers, we selected four boilers, which were equipped with wet limestone, furnace calcium injection, ammonia-based, and double-alkali FGDs, to research the influence of FGDs on the flue particulate matter (PM). The flue PM before and after the FGD were sampled using laboratory resuspension and dilution tunnel sampling methods, respectively, and the PM was analyzed for its chemical composition (i.e., ions, elements, and carbon). The results showed that the types of desulfurizers could influence the composition of the flue PM. After passing through the wet limestone, ammonia-based, and double-alkali FGDs, the proportion of Ca, NH₄⁺, and Na in PM_2.5 increased from 5.1% to 24.8%, from 0.8% to 7.3%, and from 0.9% to 1.7%, respectively. The influence of wet and dry FGDs on the flue PM were different. The fraction of ions in the PM emitted from the wet FGD were higher than those from the dry FGD. The proportion of SO₄^2- in the flue PM_2.5 increased from 2.0% and 6.7% to 9.6% and 11.9% using the wet limestone and ammonia-based FGDs, respectively, and Cl^- increased from 0.4% and 1.2% to 3.8% and 5.2%. In addition, the amount of heavy metals (e.g., Cr, Pb, Cu, Ti, and Mn) in PM_2.5 declined after the wet FGDs. The PM_2.5 emitted from the dry FGD boiler was richer in crustal elements, such as Al, Si, and Fe, than that from the wet FGDs. The wet FGDs also effected the carbonaceous components of the flue PM. After passing through the wet limestone and ammonia-based FGDs, the proportion of elemental carbon in the flue PM_2.5 decreased from 6.1% to 0.9% and from 3.6% to 0.7% respectively, but the organic carbon content did not decrease.