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51.
PM10切割器是对大气颗粒物粒径进行分离的重要部件,会影响PM10监测结果的准确性.本研究通过搭建基于静态箱法的切割器捕集效率评价系统,对进口和国产的两款旋风式PM10切割器的捕集效率进行了评价,通过使用标准规定的8种粒径单分散聚苯乙烯微球,测量并拟合了PM10切割器的捕集效率曲线,最终获取Da50(PM10切割器的捕集效率为50%时对应的空气动力学粒径)及几何标准偏差.评价结果表明,该装置能满足PM10切割器的评价需求,所评价的两个PM10切割器的Da50分别为10.43 μm和10.44 μm,性能指标均符合标准规定,且进气流量增大时,PM10切割器的Da50呈减小趋势.该研究结果对于进一步规范切割器的制造及使用具有科学意义. 相似文献
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正方形沉淀池内部水流运动模拟及设计应用 总被引:1,自引:1,他引:0
针对江苏新纪元环保有限公司自主研发的上下全截面正方形沉淀澄清池进行水流运动模拟及分析。正方形沉淀澄清池的水力特性对其沉淀效果有很大影响,在沉淀池水力设计中应通过对池型以及各种几何参数的优化,使其池内回流区范围尽可能减小,并且尽量使池内垂直断面上流速均匀平稳,研究中主要利用模型模拟正方形沉淀澄清池在不同进水流速和不同挡板布置形式下的水流流场,经过分析比较出较为合理的沉淀池运行工况以及较为合适的挡板布置形式,进而提高沉淀池的运行效率。 相似文献
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Salt marshes dominated by Spartina alterniflora and the associated networks of tidal creeks that drain them are characteristic geographical features of southeastern estuaries, important nursery habitat areas, and preferred sites for residential development. As the size of the coastal population increases, so has the number of requests for dock permits. With each new request for a dock permit, public concerns about the cumulative environmental impacts of dock proliferation on the coastal environment have increased. The objective of this particular study was to evaluate the impacts of shading by dock structures on stem densities of S. alterniflora in South Carolina coastal marshes. Shading impacts under individual docks were extrapolated to the tidal creek (local), county, and statewide scales. Dock structures were sampled both under and next to the walkway in the Charleston Harbor area of South Carolina. The density of S. alterniflora under docks was significantly lower than that which occurred next to the docks (i.e., 5 m away) for the short-form, tall-form, and both forms combined. We estimated that shading effects from dock structures in South Carolina decreased the stem density of S. alterniflora by 71%. Dock shading effects were small when evaluated from the perspective of the amount of marsh that occurs within specific tidal creeks (0.03–0.72%), in coastal counties at a maximum dock length (0.01–0.98%), or statewide (0.01–0.13%) at a maximum dock length. However, approximately 7,000 docks have been permitted over the last decade, resulting in a loss of salt marsh equivalent to 60 ha.1Denise M. Sangers present address: Office of Ocean and Coastal Resource Management, South Carolina Department of Health and Environmental Control, 1362 McMillan Avenue, Suite 400 Charleston, South Carolina 29405, USA.
2 A. Frederick Hollands present address: Hollings Marine Laboratory, National Oceanic and Atmospheric Administration, 331 Fort Johnson Road, Charleston, South Carolina 29412, USA. 相似文献
55.
No energy technology is risk free when all aspects of its utilization are taken into account. Every energy technology has some attendant direct and indirect health and safety concerns. Solar technologies examined in this paper are wind, ocean thermal energy gradients, passive, photovoltaic, satellite power systems, low- and high-temperature collectors, and central power stations, as well as tidal power. For many of these technologies, insufficient historical data are available from which to assess the health risks and environmental impacts. However, their similarities to other projects make certain predictions possible. For example, anticipated problems in worker safety in constructing ocean thermal energy conversion systems will be similar to those associated with other large-scale construction projects, like deep-sea oil drilling platforms. Occupational hazards associated with photovoltaic plant operation would be those associated with normal electricity generation, although for workers involved in the actual production of photovoltaic materials, there is some concern for the toxic effects of the materials used, including silicon, cadmium, and gallium arsenide.Satellite power systems have several unique risks. These include the effects of long-term space travel for construction workers, effects on the ozone layer and the attendant risk of skin cancer in the general public, and the as-yet-undetermined effects of long-term, low-level microwave exposure. Hazards may arise from three sources in solar heating and cooling systems: water contamination from corrosion inhibitors, heat transfer fluids, and bactericides; collector over-heating, fires, and out-gassing and handling and disposal of system fluids and wastes. Similar concerns exist for solar thermal power systems. Even passive solar systems may increase indoor exposure levels to various air pollutants and toxic substances, eitherdirectly from the solar system itself or indirectly by trapping released pollutants from furnishings, building materials, and indoor combustion.Operated by Union Carbide Corporation under contract W-7405-eng-26 for the U.S. Department of Energy. 相似文献
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轴对称渐缩回转进口旋风器流场特性研究 总被引:1,自引:0,他引:1
将普通切向单进口旋风器改进为具有轴对称渐缩回转进口的旋风器,并采用5孔探针对其流场特性进行了试验研究,给出了其速度和静压分布并与普通切向单进口旋风器进行了对比。结果表明,采用轴对称渐缩回转进口增强了流场的轴对称性,有利于同时提高效率和降低阻力。 相似文献
57.
甲烷燃烧具有环境污染小、放热量大等优点,但甲烷燃烧转化率受很多因素影响,因此,研究甲烷燃烧过程的转化率就显得尤为重要。基于计算流体力学中的涡耗散模型,运用有限容积法建立甲烷和空气非预混燃烧与扩散数学模型。针对具有3个小挡板,一个喷嘴的圆柱型燃烧器进行数值研究。结论:随着不同入口空气速度的逐渐增加,甲烷-空气非预混燃烧反应不充分,在轴向距离2 m处,反应生成的水和二氧化碳的含量逐渐减少,然而氧气增多,甲烷燃烧的转化率变低;随着不同入口甲烷速度的逐渐增加,甲烷-空气非预混燃烧反应充分,转化率变高;随着不同入口甲烷温度的增加,氧气浓度增加,甲烷-空气非预混燃烧反应不充分,转化率降低。 相似文献
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以磷矿浆为脱硫剂进行烟气脱硫研究,比较了自主创新研制的中试规模环栅式喷射鼓泡塔与工业规模的日本千代田CT-121脱硫鼓泡塔的性能。结果表明:塔压降和脱硫剂的pH值是影响脱硫效率的关键因素。鼓泡塔采用三塔串联,控制磷矿浆pH值为3.5~4.2、操作压力为7 000~7 800 Pa时,脱硫效率维持在95%左右。环栅式喷射鼓泡塔维持单塔压降约在3 000 Pa左右,磷矿浆pH值在3.7~4.3时脱硫效率可达67%。环栅式喷射鼓泡脱硫工艺以磷矿为脱硫剂,脱硫除尘效果好,系统投资少,运行费用低,并能资源化利用废渣,是适合我国国情的一项脱硫除尘技术。 相似文献