Wei Junxiao, Li Huan, Liu Jianguo
Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
Chemosphere. 2021 Aug;276:130166. doi: 10.1016/j.chemosphere.2021.130166. Epub 2021 Mar 4.
Polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) are the key pollutants of municipal solid waste incineration (MSWI). In this study, the characteristics of 17 toxic 2,3,7,8-substituted congeners in flue gas along six air pollution control devices (APCDs) were investigated in a 400 t/d moving grate furnace located in a typical megacity of Shenzhen, China. The phase distribution and removal efficiency of the different APCDs were analyzed, especially the effect of the selective catalytic reduction (SCR) device. The results showed that PCDD/F TEQs were 59.5%, 67.1%, and 72.5% partitioned into the gas phase (XAD-2 and condensed water) at the economizer outlet, fabric filter outlet, and stack, respectively. Furthermore, the three-year-old catalyst in the SCR tended to remove PCDDs, especially those in the solid phase (filter thimble). More importantly, the PCDF TEQs at the SCR inlet and outlet were 1.045 × 10 and 1.568 × 10 ng I-TEQ/Nm, respectively, which meant that the SCR might be ineffective for PCDF TEQ removal. A continuous chlorination of lower chlorinated PCDD/Fs increased the ratio of PCDFs and PCDDs from 0.73 at the SCR inlet to 1.76 at the SCR outlet. This work indicated the asynchronized inefficient removal of PCDD/Fs and nitrogen oxide for this three-year-old catalyst. The obtained results provide suggestions for the entire process of curbing PCDD/F emissions and obtaining ultra-low emission from MSWI.
多氯代二苯并 - 对 - 二噁英和多氯代二苯并呋喃（PCDD/Fs）是城市固体废物焚烧（MSWI）的主要污染物。本研究在中国深圳这个典型大城市的一座400 t/d的链条炉排炉中，对六个空气污染控制装置（APCDs）烟道气中17种有毒的2,3,7,8 - 取代同系物的特性进行了研究。分析了不同APCDs的相分布和去除效率，特别是选择性催化还原（SCR）装置的影响。结果表明，在省煤器出口、布袋除尘器出口和烟囱处，PCDD/Fs的毒性当量分别有59.5%、67.1%和72.5%分配到气相（XAD - 2和冷凝水）中。此外，SCR中使用三年的催化剂倾向于去除多氯代二苯并 - 对 - 二噁英，尤其是那些在固相（滤筒）中的。更重要的是，SCR进出口处的多氯代二苯并呋喃毒性当量分别为1.045×10和1.568×10 ng I - TEQ/Nm，这意味着SCR对多氯代二苯并呋喃毒性当量的去除可能无效。较低氯代的PCDD/Fs的连续氯化使多氯代二苯并呋喃与多氯代二苯并 - 对 - 二噁英的比例从SCR入口处的0.73增加到SCR出口处的1.76。这项工作表明，对于这种使用三年的催化剂，PCDD/Fs和氮氧化物的去除存在不同步且效率低下的情况。所得结果为抑制PCDD/Fs排放以及实现MSWI超低排放的全过程提供了建议。
