EXPERIMENTAL STUDY ON DIOXINS CONTROL DURING LOW-TEMPERATURE PYROLYSIS OF DOMESTIC WASTE
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摘要: 针对垃圾热解烟气中二噁英排放不达标的现象,在分析垃圾热解机理及二噁英产生机制的基础上,提出了定量供氧、分层控制二噁英的方法;并采用数值分析和试验测试相结合的方法,对炉内气流组织及垃圾热解过程进行模拟分析。结果表明:热解炉内部气流整体分布较为均匀,能够保证垃圾稳定热解。热解炉沿轴向方向上存在温度分层,与理论分析结果一致,但燃烧层与热解层之间的过渡层存在二噁英合成气氛;热解炉温度实测结果与模拟结果整体吻合较好;空气过剩系数为0.3时热解炉运行情况更有利于减少二噁英的产生。现场试验发现,热解炉出口烟气中除颗粒物浓度超标外,其余常规污染物及二噁英排放浓度均满足GB 18485-2014《生活垃圾焚烧污染控制标准》;而市面上常见炉型二噁英出口浓度为0.44 ng-TEQ/m3,超过GB 18485-2014限值0.1 ng-TEQ/m3;2种炉型试验结果对比证明,在热解炉布气均匀的基础上,通过定量供氧、分层控制的方法可以有效抑制烟气中二噁英的生成。该成果可为生活垃圾低温热解过程二噁英的控制提供理论参考。Abstract: Based on the phenomenon of substandard dioxin emission from waste pyrolysis flue gas, this paper proposed a method of quantitative oxygen supply and stratified dioxin control based on the analysis of the waste pyrolysis and dioxin generation mechanism, used a combination of numerical analysis and experimental test to simulate the airflow organization inside the furnace and waste pyrolysis process, and discussed the effect of air supply on dioxin synthesis. The results showed that the overall distribution of airflow inside the pyrolysis furnace was relatively uniform, which ensured the stable pyrolysis of waste. The temperature stratification along the axial direction of the pyrolysis furnace was consistent with the theoretical analysis, but there was a dioxin synthesis atmosphere in the transition layer between the combustion layer and the pyrolysis layer; the measured results of the pyrolysis furnace temperature were in good agreement with the simulation results as a whole; a comprehensive comparison suggested that operation of the pyrolysis furnace with an air excess factor of 0.3 was more conducive to reducing dioxin generation, and the waste treatment capacity was 2.4 t/d. The field test result showed that, except for the particulate matter concentration exceeded the standard, the other conventional pollutants from pyrolysis furnace outlet flue gas and dioxin emission concentration met the Standard for Pollution Control of Domestic Waste Incineration (GB 18485-2014). The commercially available common furnace model dioxin outlet concentration was 0.44 ng-TEQ/m3, exceeding the national emission standard limit of 0.1 ng-TEQ/m3. The experimental results of the two furnace types proved that dioxin generation in the flue gas could be effectively suppressed by quantitative oxygen supply and stratified control on the basis of uniform gas distribution in the pyrolysis furnace. The study could provide a theoretical basis for the control of dioxins in low-temperature pyrolysis of domestic waste.
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[1] 中华人民共和国住房和城乡建设部. 中国城市建设统计年鉴(2020)[M]. 北京:中国统计出版社, 2021. [2] 张国治, 魏珞宇, 葛一洪, 等. 我国农村生活垃圾处理现状及其展望[J]. 中国沼气, 2021, 39(4):54-61. [3] VAVERKOVÁ M D. Landfill impacts on the environment[J]. Geosciences, 2019, 9(10):431. [4] TITTO E, SAVINO A. Environmental and health risks related to waste incineration[J]. Waste Management & Research, 2019, 37(10):976-986. [5] 桂莉. 农村生活垃圾热解污染物排放特征研究[D]. 广州:华南理工大学, 2014. [6] 党小庆, 夏夕科, 吕涛, 等. 生活垃圾热解烟气净化设备研究与应用[C]//中国电除尘学术会议. 安徽, 2013. [7] 黄付平, 黄智宁, 谢启军, 等. 低温热解耦合高压等离子体技术处理农村生活垃圾工程应用[J]. 环境工程, 2019, 37(5):196-199. [8] 黄宇钊, 韩彪, 潘翠, 等. 新型稳定控制热解炉处理农村生活垃圾的应用[J]. 环境科技, 2020, 33(1):41-44. [9] 雷鸣, 海景, 程江, 等. 小型生活垃圾热处理炉二噁英和重金属的排放特征[J]. 中国环境科学, 2017, 37(10):3836-3844. [10] 孙宏宇, 董玉平, 周淑霞, 等. 基于Fluent的固定床生物质气化炉冷态压力场研究[J]. 农业机械学报, 2010, 41(11):94-97,104. [11] 肖波, 汪莹莹, 周新平, 等. 基于烟气加热的新型垃圾热解气化炉热工特性数值模拟[J]. 环境工程, 2007,25(2):52-55. [12] MELLIN P, KANTARELIS E, YANG W. Computational fluid dynamics modeling of biomass fast pyrolysis in a fluidized bed reactor, using a comprehensive chemistry scheme[J]. Fuel, 2014, 117(pt.A):704-715. [13] 陆杰, 金保昇. 生物质流化床气化的三维数值模拟[J]. 太阳能学报, 2018, 39(10):2863-2868. [14] VOGG H, METZGER M, STIEGLITZ L. Recent findings on the formation and decomposition of PCDD/PCDF in municipal solid waste incineration[J]. Waste Management & Research, 1987, 5(1):285-294. [15] CAI P T, FU J Y, ZHAN M X, et al. Formation mechanism and influencing factors of dioxins during incineration of mineralized refuse[J]. Journal of Cleaner Production, 2022, 342:130762. [16] JIE Y, LI X, MI Y, et al. Denovo tests on medical waste incineration fly ash:effect of oxygen and temperature[J]. Fresenius Environmental Bulletin, 2015, 24(2a):587-595. [17] ADDINK R, OLIE K. Role of oxygen in formation of polychlorinated dibenzo-p-dioxins/dibenzofurans from carbon on fly ash[J]. Environmental Science & Technology, 1995, 29(6):1586-1590. [18] TUPPURAINEN K, HALONEN I, RUOKOJÄRVI P, et al. Formation of PCDDs and PCDFs in municipal waste incineration and its inhibition mechanisms:a review[J]. Chemosphere, 1998, 36(7):1493-1511. [19] 杨明辉, 陈祎, 刘金和, 等. PVC热解特性及Cl的析出过程研究[J]. 工业加热, 2020, 49(5):44-47. [20] 田中训, 刘伟军. 聚氯乙烯废弃物的热解特性与处理[J]. 塑料, 2022, 51(1):121-126,130. [21] 张睿智, 罗永浩. 用于低二噁英热化学转化过程的低温预先脱氯方法和装置:CN111330942A[P]. 2020-06-26.
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