供热厂燃煤烟气可凝结颗粒物排放特征及其在湿法脱硫系统中的转化

燃煤源是城市环境大气颗粒物的重要来源，燃煤产生的颗粒物由可过滤颗粒物 (FPM) 与可凝结颗粒物 (CPM) 两部分组成，且CPM在排放的总颗粒物中占比较高。采用EPA Method 202方法，对燃煤供热厂湿法脱硫系统 (WFGD) 进口及出口烟气进行平行取样，并对燃煤烟气中CPM质量浓度、成分组分、金属元素、水溶性离子及WFGD对CPM的脱除作用进行研究。结果表明，WFGD进口与出口处CPM在TPM中均占有主导地位，且CPM中以CPM无机组分为主。CPM中含量较高的10种金属元素为Na、Ca、Al、K、Fe、Zn、Mn、Ba、Cr、Ti，其中Na、Ca、Al三种金属元素之和占总金属元素的80%以上。燃煤烟气CPM中水溶性离子以SO₄²⁻为主，其中WFGD进口处SO₄²⁻占CPM总水溶性离子的59.49%，WFGD出口处SO₄²⁻占CPM总水溶性离子的81.07%。通过对WFGD进口与出口处颗粒物浓度对比发现WFGD对CPM的脱除效率为69.29%，对CPM有机组分脱除效率为负，对CPM无机组分的脱除效率为77.27%。WFGD对10种金属元素的脱除效率为55.52%，WFGD对总水溶性离子的脱除效率为78.74%。本研究结果可为供热厂的可凝结颗粒物排放源头控制提供参考。

Emission characteristics of condensable particulate matter from coal-fired flue gas of heat supply plant and its transformation in WFGD

Coal burning source is an important source of atmospheric particulate matter in urban environment. The particulate matter produced by coal burning is composed of filterable particulate matter (FPM)and condensable particulate matter (CPM),and CPM accounts for a high proportion of the total particulate matter emitted. There is a lack of research on the emission and detection of CPM in China. In this study, EPA method 202 was used to sample the inlet and outlet flue gas of WFGD in coal-fired heating plant in parallel, and the CPM mass concentration, composition, metal elements, water-soluble ions and the removal effect of WFGD on CPM in coal-fired flue gas were studied. The results show that CPM at the inlet and outlet of WFGD plays a dominant role in TPM, and CPM inorganic component is the main component in CPM. The 10 metal elements with high content in CPM were Na, Ca, Al, K, Fe, Zn, Mn, Ba, Cr and Ti, and the sum of Na, Ca and Al accounted for more than 80% of the total metal elements. The water-soluble ions in CPM of coal-fired flue gas are mainly SO42−, of which SO42− at WFGD inlet accounts for 59.49% of the total water-soluble ions in CPM, and SO42− at WFGD outlet accounts for 81.07% of the total water-soluble ions in CPM. By comparing the particle concentration at the inlet and outlet of WFGD, it is found that the removal efficiency of WFGD for CPM is 69.29%, the removal efficiency of organic components of CPM is negative, and the removal efficiency of inorganic components of CPM is 77.27%.The removal efficiency of WFGD for 10 metal elements was 55.52%, and the removal efficiency of WFGD for total water-soluble ions was 78.74%.