京津冀区域民用散煤燃烧对环境空气影响的光化学烟雾箱模拟研究

发布时间：2018-03-26 19:19

本文选题：民用散煤　切入点：小型室外光化学烟雾箱　出处：《吉林大学》2017年硕士论文

【摘要】：我国富煤、贫油、少气的资源赋存条件决定了煤炭在能源结构中的主导地位,民用散煤燃烧排放的PM_(2.5)是造成当前环境空气质量问题的主要因素之一。本文选用市场上常见的民用炉具和蜂窝煤模拟民用散煤污染源,通过直接测量和统计平均的方法考察了实验所采用的充分燃烧状态下的NO_x和PM_(2.5)一次排放因子,分别为0.17 kg/t和3×10-3 kg/t。结合民用型煤使用量的调研数据,在本文所模拟的充分燃烧状态下,京津冀区域采暖季民用燃煤源向大气中直接排放的NO_x和PM_(2.5)分别约为243.29 t和4.29 t。本文使用自主设计加工的两个平行放置的小型室外光化学烟雾箱测试了一次污染物在大气中转化生成二次颗粒物的反应特性。其中一个烟雾箱通入环境空气作为背景箱,另一个引入模拟民用散煤污染源排放的烟气作为实验箱,实验在接近真实的自然气象条件下(温度、相对湿度、太阳辐射、紫外辐射)进行。首先对所使用的光化学烟雾箱模拟实验系统的可靠性进行表征,内容包括遮光性、密闭性、混合性和壁效应性能。表征结果显示,遮光状态可完全避免环境紫外线影响,确保实验初始状态的稳定性;烟雾箱有效混合时间3 min,NO_2在实验箱和背景箱中的半衰期分别是231 h和173.25 h;O_3的半衰期分别是51.31 h和46.20 h,实验系统满足二次颗粒物生成模拟实验的需求。二次颗粒物生成的模拟实验结果显示,即使在冬季北方地区太阳紫外辐射较弱的情况下,依然可以观测到明显的大气光化学过程。实验中测得的最大二次颗粒物生成速率可达到0.02μg/(m3·s);初始NO_x/VOCs比对一次污染物的大气光化学行为有明显影响:反应处于NO_x控制区时,NO_x浓度的升高可显著促进光化学反应的进行,并观测到大量二次颗粒物生成和粒径的增长;反应处于VOCs控制区时,过量的NO_x对二次污染物(二次颗粒物和臭氧)的生成起到显著的抑制效果。对不同实验过程中颗粒物进行分析,结果表明:颗粒物有机碳/无机碳(OC/EC)分析结果均大于2,并且随着反应的进行,OC/EC呈现出持续增加趋势;指示气溶胶老化的邻苯二甲酸所占比例随实验进程有增加的趋势;单颗粒物的粒径不断增长,其中的元素也不断丰富,但即使元素种类不断增多,C所占的质量分数仍然增加,以上实验结果均说明实验箱中的挥发性有机物(VOCs)经光化学反应生成二次有机气溶胶。最后,基于本文得到的二次颗粒物生成速率估算了京津冀区域民用散煤燃烧排放污染物在大气中光氧化生成二次颗粒物的环境影响。实验所得的二次颗粒物最大生成速率约为0.02μg/(m3·s),计算得出在实验燃烧状态(充分燃烧)和理想的气象条件下民用散煤燃烧排放污染物转化生成二次颗粒物的生成因子约为4×10-3 kg/t,京津冀区域民用散烧煤排放生成的二次颗粒物质量约为5.72 t,稍高于本文测量得到一次颗粒物排放量,表明既有的冬季民用散煤排放对区域环境空气PM_(2.5)污染的贡献率研究结果可能严重低估,应综合考虑一次和二次颗粒物的复合影响。
[Abstract]:The rich coal, oil, and gas resources conditions determine the dominant position of coal in the energy structure, coal combustion emissions of civilian PM_ (2.5) is one of the main factors causing the current ambient air quality problems. This paper selects the common market of domestic stove and honeycomb coal civilian bulk coal pollution source simulation, combustion under the condition of NO_x and PM_ fully employed in the study were investigated by the method of direct measurement and statistical average (2.5) an emission factor, respectively 0.17 kg/t and 3 * 10-3 kg/t. with the survey data of civil coal consumption, full combustion state simulation in this paper, the Beijing Tianjin Hebei region civilian coal-fired heating season the source to the atmospheric emissions of NO_x and PM_ directly (2.5) were approximately two parallel small outdoor smog chamber of 243.29 T and 4.29 T. using self design and processing of a pollutant in atmospheric test The transfer of two generation particle responses. One of the smoke box pass into the air as a background box, another civilian bulk coal into gas simulation pollution as the experimental box, experiments in the natural weather conditions close to the real conditions (temperature, relative humidity, solar radiation, ultraviolet radiation) first. To characterize the photochemical smog box used in the simulation of the reliability of the system, including shading, airtight, mixed and wall effect performance. The results show that shading condition can completely avoid the effects of environmental ultraviolet radiation, to ensure stability of the experimental initial state; effective mixing time 3 min smoke box, the half-life of NO_2 in experiment box and background box are respectively 231 h and 173.25 h respectively; the half-life of O_3 is 51.31 h and 46.20 h, two times to meet the experimental system of particle formation simulation needs. Two particles generated The simulation results show that even in the northern winter solar UV radiation is weak, can still be observed obviously. The maximum photochemical process of two particle formation rate measured in experiments can reach 0.02 g/ (M3 - s); have obvious effects of atmospheric photochemical behavior of initial NO_x/VOCs ratio of primary pollutants the reaction in the NO_x control region, the increase of NO_x concentration can significantly promote the photochemical reaction, and observed a large number of two particle formation and growth of grain size; VOCs reaction in control area, the excess NO_x two times (two times of pollutant particles and ozone generation) plays a significant inhibitory effect for particles of different experimental process were analyzed, the results show that the particulate organic carbon and inorganic carbon (OC/EC) analysis results are greater than 2, and with the reaction, OC/EC showed increasing trend indicating gas; Ortho benzoic acid sol aging two proportion with experimental process had an increasing trend; the single particle size increasing, the elements were enriched, but even if the element type is increasing, C accounts for the mass fraction still increases, above results are that the volatile organic compounds in the experimental box (VOCs the photochemical reaction of two times) organic aerosol. Finally, the two particle formation rate estimated by the Beijing Tianjin Hebei region civilian bulk coal combustion emissions of pollutants in the atmosphere light oxidation two particles. The experimental results based on the environmental impact of the two particle of the maximum production rate is about 0.02 g/ (M3 - s), calculated in the combustion state (combustion) and meteorological conditions under the ideal civilian bulk coal combustion emissions of pollutants into the two particle formation factor is about 4 * 10-3 kg/t, Beijing, Tianjin and Hebei areas With the two particulate mass scattered coal emissions generated is about 5.72 T, slightly higher than the measured primary particulate matter emissions, that the existing civil winter scattered coal emissions on regional air PM_ (2.5) results may seriously underestimate the contribution rate of pollution, should consider the impact of a composite and two secondary particles.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X515

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