生物质直燃过程中挥发性有机物的排放特征及其大气化学作用

Volatile organic compounds (VOCs) play a key role to the formation of atmoshperic complex pollution and are harmful to the public health. Biomass direct combustion is one of the most important emission source of VOCs. With the improvement of status of biofuel in our energy strategy , the influence of the VOCs emission from the direct combustion of biomass cannot be neglected. However, our understanding of the VOCs composition, formaiton processes and emission processes remains very poor, especially for industrial biomass fuel in direct combusiton. This is an obstacle to the effective control of VOCs emissions. This project will employ on- and off-line analytical techniques with thermogavimetry experiments and combustion experiments in horizontal fixed-bed combustor,one dimensional grate firing combsutor and flusized bed combustor to reveal the general VOCs emission rules from the direct combustion of biomass, and the specifical characteristics of VOCs for different biomass fuels in different combsution technologies. The characteristics and emission patterns of VOCs source profile will be analyzed through the way of VOCs source profile normalization. After analyzed the ozone formation potential and the atmospheric chemistry reactivity, the chemical action of VOCs to the atmoshperic will be discussed. The controlling factors to VOCs emissions will be gaven at last. This study will be valuable in the understanding of cleaning combustion of biomass fuel and in the way to control VOCs for the science and the reality.

挥发性有机物（VOCs）是形成大气复合污染和危害公众健康的重要污染物。生物质燃烧是VOCs的重要排放源。随着生物质燃料在我国能源战略中地位的进一步提高，其排放的VOCs带来的环境影响不容忽视。但目前生物质直燃尤其是工业直燃中VOCs污染物化学组成、生成和排放过程缺乏研究，给VOCs的有效控制带来困难。为此，本项目综合运用离线和在线测量技术结合热重、管式炉、一维层燃和流化床等多种燃烧模拟实验手段，揭示生物质直燃中VOCs排放的共性规律，及不同生物质在不同直燃技术中的个性排放特征；并通过VOCs源谱标准化分析和臭氧生成潜力及大气化学活性分析，阐明不同直燃技术中生物质VOCs的源谱特点及其大气化学作用；进而提出影响VOCs排放的控制因素。本项目对探讨生物质燃料的清洁燃烧机理和VOCs的控制机理具有重要的科学价值和现实意义。

挥发性有机物（VOCs）是形成大气复合污染和危害公众健康的重要污染物。生物质燃烧是VOCs的重要排放源。本项目综合多种燃烧模拟实验手段和22台次生物质燃料锅炉的外场观测等数据，对生物质燃料燃烧特性、不同燃烧阶段VOCs排放规律、影响VOCs排放特性的因素以及VOCs成分谱等进行了深入研究。结果表明，生物质燃料燃烧分为干燥、挥发份析出、过渡以及残碳燃烧四个阶段，不同阶段挥发性有机物排放量差别明显，以挥发份析出阶段和过渡阶段排放的总挥发性有机物量最高。不同类型生物质燃料在排放浓度和具体组分占比上有个体差异，但也表现了较一致的特征，整个燃烧过程不同燃料环戊烷、乙烯、反-2-丁烯、丙酮和氯甲烷占比大。对广东省25台次燃生物质燃料锅炉进行了外场观测，不同锅炉VOCs总浓度差异显著，表明数值型生物质燃烧VOCs排放因子将存在很大不确定性。烷烃的排放以环戊烷为主，烯烃以乙烯、1,3-丁二烯、1-丁烯和顺-2-丁烯为主，芳香烃以苯和甲苯为主，OVOCs以丙酮、2-丁酮为主，卤代烃以氯甲烷为主。VOCs排放因子介于0.021~0.15g/kg。臭氧生成潜势贡献最大的为烯烃，其次为烷烃。温度和氧浓度及其交互作用，以及锅炉负荷变化对VOCs的浓度均有显著影响。最后，针对生物质燃料工业燃烧过程中环境污染问题，从燃烧全过程角度，提出了对应的管理措施。