| 摘要: |
| 排放因子是估算污染物排放量的重要参数，为获取可靠的、有区域特征的固体燃料排放因子，2018年在我国西部9个省/自治区利用稀释采样系统入户收集了226个固体燃料燃烧样本，获得了薪柴、秸秆和煤在不同类型炉具中燃烧排放CO2、CO、OC、EC、PM2.5的排放因子。结果表明，秸秆类较易燃烧的燃料有较高的OC、EC、PM2.5排放因子，煤有较高的CO2、CO排放因子。炉灶类型对薪柴的OC、PM2.5的排放因子影响稍大，薪柴在炕中燃烧的OC、PM2.5排放因子比在砖灶和铁炉高约2—3.1倍，但秸秆在不同炉具中的排放因子差异较小。受不同区域燃料和炉灶类型以及操作习惯差异的共同影响，排放因子呈现明显的区域性差异，高CO2排放因子分布在以煤作为主要燃料的区域，高OC、EC、PM2.5排放因子分布在以生物质作为主要燃料的区域，并且CO、OC和PM2.5排放因子的区域分布呈现一定的相关性。 |
| 关键词: 农村地区 中国西部 固体燃料 污染排放 排放因子 |
| DOI：10.7515/JEE222078 |
| CSTR： |
| 分类号: |
| 基金项目:国家自然科学基金项目（41877404）；西部之光“西部青年学者”项目（XAB2021YN06）；陕西省自然科学基础研究计划（2020JQ-982） |
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| Measurement and distribution characteristics of emission factors of pollutant emission in solid fuel combustion in rural areas of western China |
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YANG Leting, ZHANG Ningning, ZHANG Yong, WANG Yi
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1. Key Laboratory of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. CAS Center for Excellence in Quaternary Science and Global Change, Xi’an 710061, China
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| Abstract: |
| Background, aim, and scope Solid fuels such as biomass and bulk coal are the primary energy sources for cooking and heating in rural areas of China. However, low combustion efficiency and the large amounts of pollutants emissions from solid fuels combustion cause a decline in regional air quality and damage to human health. Regional emission factors are a key factor in evaluating regional pollutant emissions which are important for regional air pollution control. In order to localize the emission factors for western China’s rural areas, a portable dilution sampling system was designed and established, and the emission factors of CO2, CO, OC, EC and PM2.5 were calculated after field investigation and sampling. Materials and methods A portable dilution sampling system was used to collect the flue gas from solid fuel combustion. The concentrations of CO2 and CO were measured by in-line instruments. The filter was weighed by a high precision electronic balance, OC and EC were analyzed by a DRI model 2001A OC/EC carbon analyzer, and the emission factors were calculated following carbon balance method. Results Because coal has higher carbon content, the emission factors of CO2 and CO of coal are (2375.3±365.28) g·kg−1 and (147.11±126.92) g·kg−1, respectively, which are larger than those of firewood and straw. Firewood and straw have higher emission factors of OC, EC and PM2.5, since they burn less efficiently than coal and tend to produce more pollutants. In this study, the values of emission factors in this study are generally higher than the results measured in lab. This could be due to the fact that lab can control the fuel and combustion process more precisely, while uncontrolled combustion releases more pollutants in real life. Additionally, the type of stove has a great influence on emission factors of OC and PM2.5 of fuel wood. The emission factors for Kang were found to be about 2—3.1 times higher than those for brick stove and metal stove. Burning coal in metal stoves and firewood in brick stoves can relatively reduce emissions of solid fuel pollutants in rural areas. It is important to note that the emission factors of CO2, CO, OC, EC and PM2.5 present obviously regional difference due to differences of combustion habits in different regions. Discussion Analyzing the variations of emission factors of CO2, CO, OC, EC and PM2.5, it was found that fuel types and stove types have effect on emission factors and combustion habits cause regional distribution of emission factors. Coal has higher CO2 and CO emission factors due to its high carbon content, while straw and firewood have higher OC, EC and PM2.5 emission factors because of their relatively insufficient combustion, which tends to produce more pollutants. The type of stove had a greater impact on the OC and PM2.5 emission factors when using firewood, but had a lesser impact on the emission factors when using straw. The values in this study were slightly higher compared to the laboratory results, possibly due to the release of more pollutants from uncontrolled combustion processes in real life situations. Significant geographical differences in emission factors exist due to variations in combustion habits across different regions. The high CO2 emission factors are distributed in the regions where coal is the main fuel, and the high OC, EC and PM2.5 emission factors are distributed in the regions where biomass is the main fuel. Conclusions Emission factors are influenced by combustion habits such as the type of fuel and stove. Therefore, localization of emission factors is helpful for obtaining more accurate emission inventories. Recommendations and perspectives The findings of this study address the existing gap in regional emission factors, which can significantly reduce the variability of emission results, and provide basic data for assessing pollutant emissions from rural areas in China. Further investigation is necessary to identify specific reasons for differences between field and laboratory measurements, as the complex influences of field measurements can significantly impact emissions. |
| Key words: rural areas western China solid fuels pollution emission emission factor |
