THE OPTIMIZED EXPERIMENTS OF MILLING SYSTEM FOR COAL-FIRED BOILER

该文在磨煤机出力变化时,进行了优化分离器转速和一次风量的试验.试验发现:当磨煤机出力为12 kg/s时,建议分离器转速为85r/min、风粉比为2.0;当磨煤机出力为8 kg/s时,建议分离器转速为70r/min、风粉比为2.5.文中得出的风/粉比和分离器转速/给煤量曲线可以指导磨煤机的运行

燃煤锅炉制粉系统的优化运行试验

该文在磨煤机出力变化时，进行了优化分离器转速和一次风量的试验。试验发现：当磨煤机出力为12kg／s时，建议分离器转速为85r／min、风粉比为2．0；当磨煤机出力为8kg／s时，建议分离器转速为70r／min、风粉比为2．5。文中得出的风／粉比和分离器转速／给煤量曲线可以指导磨煤机的运行

济南市城区大气挥发性有机物污染特征及来源

为研究济南市城区环境空气挥发性有机物(VOCs)污染特征及来源,2020-2021年于济南市城区开展了逐月离线观测,并于2020年6月开展加密观测,分析了VOCs年度、季节、日体积分数变化特征、化学组成及臭氧生成潜势,并利用特征比值法和正定矩阵因子分解模型解析了VOCs来源.结果表明,2021年济南市VOCs年均体积分数为(35.70±16.58)×10-9,较2020年改善14.48%,烷烃和OVOCs为VOCs中占比最高的两类组分.2020年VOCs体积分数均值呈冬高夏低季节特征,而2021年呈夏高春低季节特征,受济南市VOCs专项整治行动及北京冬奥会空气质量保障措施影响,2021年冬季VOCs体积分数均值较2020年改善最为明显,改善幅度为31.08%,2020年春季芳香烃贡献显著,可能与疫情管控后企业陆续复工复产有关.2020、2021年排名前十的组分主要为烷烃类与OVOCs,如丙烷、乙烷、正丁烷、甲醛、丙酮、乙醛等物种.2021年济南市城区OFP年均值为239.39μg/m3,较2020年下降22.46%,烷烃、炔烃、芳香烃、卤代烃OFP改善幅度分别为29.28%、3.09%、67.93%、83.49%,烯烃OFP明显上升,上升幅度为37.49%,OVOCs维持在较高水平.2020、2021年OFP排名前十的物种主要包括甲醛、乙醛、乙烯、1-丁烯、丙烯、对/间二甲苯等.臭氧重污染期间TVOCs体积分数日变化特征呈现明显的早晚高峰特征,中午时段为一天中的低值,夜间维持在较高水平.PMF解析结果表明:VOCs主要来源于工业源、燃烧源、油气挥发源、机动车尾气排放源、溶剂使用源、植物源及二次生成源,机动车尾气排放源、燃烧源及工业源为济南市VOCs的重点管控源. To study the characteristics and sources of ambient volatile organic compounds (VOCs) in urban Jinan, monthly offline observations from 2020 to 2021 and intensive observations in June 2020 were conducted. The inter-annual, seasonal, and daily concentration changes, chemical composition, and ozone formation potential (OFP) of VOCs were analyzed. Sources of VOCs were analyzed using the tracer ratio method and positive matrix factorization (PMF) model. The results indicated that the annual average mixing ratio of VOCs in urban Jinan in 2021 was (35.70 ± 16.58) ×10-9, an improvement of 14.48% compared to 2020, with alkanes and oxygenated VOCs (OVOCs) were the two major components of VOCs. The seasonal characteristics of the average mixing ratio of VOCs in 2020 showed a high in winter and a low in summer, while in 2021, it showed an increase in summer and a low in spring. Influenced by the special rectification action of VOCs in Jinan and the air quality assurance measures for the Beijing Winter Olympics, the average mixing ratio of VOCs in winter 2021 improved significantly compared to 2020, with an improvement rate of 31.08%. Aromatic hydrocarbons contributed significantly in the spring of 2020, which might be related to enterprises' gradual resumption of work under epidemic control. The top ten components in 2020 and 2021 are mainly alkanes and OVOCs, such as propane, ethane, n-butane, formaldehyde, acetone, and acetaldehyde. The annual value of OFP was 239.39µg/m3 in 2021, a decrease of 22.46% compared to 2020. The improvement rates of OFP for alkanes, alkynes, aromatics, and halogenated hydrocarbons were 29.28%, 3.09%, 67.93%, and 83.49%, respectively. The OFP for olefins increased significantly, with an increase rate of 37.49%. OVOCs remained at a relatively high level. The top ten species in OFP rankings in 2020 and 2021 mainly include formaldehyde, acetaldehyde, ethylene, 1-butene, propylene, and para/meta xylene. During heavy ozone pollution episodes, the daily variation characteristics of TVOCs volume fraction showed obvious morning and evening peak characteristics, with the noon period being the low value of the day and maintaining a high level at night. The PMF analysis showed that VOCs mainly came from industrial sources, combustion sources, oil and gas volatilization, motor vehicle exhaust emissions, solvent use sources, plant emissions, and secondary generation sources. Motor vehicle exhaust emissions, combustion sources, and industrial sources were critical sources of VOCs for O3 pollution control in Jinan. © 2024 Chinese Society for Environmental Sciences. All rights reserved