28 November 2014, Volume 32 Issue 33

    

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  An Overview on the Control of Urban Air Pollution

  CHEN Guangren, ZHU Yehua

  Science & Technology Review. 2014, 32(33): 15-22. https://doi.org/10.3981/j.issn.1000-7857.2014.33.001

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  Ecological environment is the key condition to support human life and maintain sustainable development. Environment protection is not only the important issues of common concern to the whole world, but also an important share responsibility for human. Since the 18th century Industrial revolution, serious air pollution events have occurred in many countries around the world. In order to learn the lessons of the air pollution, and summary the experiences on the treatment of air pollution, the major air pollution events occurred and the treatment measures of air pollution in some countries around the world were introduced in the paper. The efforts for control the China's air pollution was also described. The developments and requirements on air pollution control were discussed.
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  PM₁₀ and PM_2.5 Emission Control by Electrostatic Precipitator (ESP) for Coal-fired Power Plants I: ESP Sizing and Applications

  WANG Shilong, CHEN Ying, HAN Ping, ZHANG Guoqing, ZHENG Qinzhen, SHEN Xinjun, LI Shuran, YAN Keping

  Science & Technology Review. 2014, 32(33): 23-33. https://doi.org/10.3981/j.issn.1000-7857.2014.33.002

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  This paper discusses electrostatic precipitation for fine particle emission control. According to the so-called electrostatic precipitator (ESP) index, a novel ESP sizing method is presented for both mechanical and electrical specifications. By using threephase rectifier transformer power sources, ESPs give very high collection for fine particle emission control. The ratio of PM_2.5 over PM₁₀ is between 6% and 20%. When PM₁₀ emission is around 5-15 mg/m³, PM_2.5 is below 2.5 mg/m³. By upgrading ESP and flue gas desulfurization (FGD), particle emissions can be reduced to below 5 mg/m³, and PM_2.5 below 2.5 mg/m³.
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  PM₁₀ and PM_2.5 Emission Control by Electrostatic Precipitator (ESP) for Coal-fired Power Plants II: Evaluation of ESP Upgrading in Terms of PM₁₀ and PM_2.5 Emission Reduction with A 660 MW Generator

  WANG Shilong

  Science & Technology Review. 2014, 32(33): 34-38. https://doi.org/10.3981/j.issn.1000-7857.2014.33.003

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  This paper discusses PM₁₀ and PM_2.5 emission reduction by upgrading four-filed electrostatic precipitators (ESPs) with a 660 MW coal-fired power generator. By using a traditional single-phase high-voltage rectifier transformer (T/R), the PM, PM₁₀ and PM_2.5 emissions are around 75, 63 and 23 mg/m³, respectively. After upgrading the T/R by using a three-phase T/R, the PM, PM₁₀ and PM_2.5 emissions drop below about 18, 15 and 2.5 mg/m³, respectively. Their reduction efficiencies are around 76%, 76% and 89%, respectively.
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  PM₁₀ and PM_2.5 Emission Control by Electrostatic Precipitator(ESP)for Coal-fired Power Plants III: Applications with A 4×330 MW Power Plant

  WANG Shilong, CHEN Ying, HAN Ping, XU Bing, LI Zengzhi, GUO Zhanwei, ZHENG Qinzhen, SHEN Xinjun, LI Shuran, YAN Keping

  Science & Technology Review. 2014, 32(33): 39-42. https://doi.org/10.3981/j.issn.1000-7857.2014.33.004

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  This paper discusses how to upgrade electrostatic precipitators (ESPs) with four 330 MW coal-fired generators. For the two four-field ESPs, the upgrading includes replacement of high-voltage electrodes and the high-voltage power sources. For the two five-field ESPs, only the power sources are retrofitted. The ESP outlet PM₁₀ and PM_2.5 emissions are less than 15 and 2 mg/m³, respectively. The flue gas desulfurization (FGD) can be effective for PM₁₀ emission reduction, but not for PM_2.5. This paper also presents the rapping and gas temperature effects on particle emission. When reducing the gas temperature from 150-160℃ to about 110℃, PM_2.5 emission from the ESP or FGD is always less than 2 mg/m³.
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  PM₁₀ and PM_2.5 Emission Control by Electrostatic Precipitator (ESP) for Coal-fired Power Plants IV: Investigations on Electrostatic Precipitation by Means of 2D PIV Technique

  SHEN Xinjun, ZHENG Qinzhen, NING Zhiyuan, WANG Shilong, HAN Ping, YAN Keping

  Science & Technology Review. 2014, 32(33): 43-50. https://doi.org/10.3981/j.issn.1000-7857.2014.33.005

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  This paper discusses PM₁₀ (particle matter with a diameter less than 10 μm) grade collection efficiencies of a laboratory electrostatic precipitator (ESP) in terms of the electric field, corona discharge power, and gas flow patterns by means of the particle image velocimetry(PIV)and the electrical low pressure impactor (ELPI) technique. The wire-plate ESP has a plate-plate distance of 200 mm, together with a single or two high-voltage electrodes. Moxa-moxibustion smoke is used as the tracer for evaluation of the gas flow and particle grade collection efficiency. Experiments, performed in air with a total gas flow rate of 85 m³/h and initial particle mass concentration of around 33 mg/m³, show that with increasing the field strength or corona discharge power, the flow changes from regular vortexes around the corona wire to multi-vortexes inter-reacting each other. As a result, optimizing the distribution of corona discharge ion wind is the key to increase PM₁₀ collection efficiencies and reduce the power consumption. In terms of the particle number concentration and the applied electric field or corona discharge power, two ESP performance regions can be distinguished: Below 3 kV/cm, the grade collection efficiency increases with the rise of field strength or ESP index; it tends to saturate or drop when the field becomes higher than 3 kV/cm.
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  Emission Characteristics of Multiple Pollutants from Iron- steel Sintering Flue Gas and Review of Control Technologies

  ZHU Tingyu, LIU Qing, LI Yuran, YAN Xiaomiao, QI Feng, YE Meng

  Science & Technology Review. 2014, 32(33): 51-56. https://doi.org/10.3981/j.issn.1000-7857.2014.33.006

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  The emission characteristics measurement of the iron-steel sintering flue gas shows that the SO₂ concentration is high in the middle of the sintering machine and low at the head and tail parts along the sintering direction. The dioxins concentration has positive a correlation with the flue gas temperature, and reaches a peak value as the temperature above 250℃. The proportion of the SO₂ concentration below 2000 mg/m³ occupies 63%, and the over 2000 mg/m³ occupies 37%. Therefore, the desulfurization efficiency should be higher than 90% and 96%, respectively. The proportion of the NO_x concentration below 300 mg/m³ is 86%, and the flue gas can be discharged directly without treatment. However, the proportion of NO_x concentration between 300 and 600 mg/m³ is 14%, and the denitration efficiency should be higher than 50%. The dioxins concentration between 1.0 and 5.0 ng TEQ/m³ has to be reduced to reach the national standard. According to the emission characteristics of high SO₂ and dioxins concentrations from the sintering flue gas, four kinds of multi-pollutant simultaneous control technologies are reviewed. Activated carbon adsorption belongs to an integrated control technology, while SDA (spray drying adsorption), MEROS (maximized emission reduction of sintering) and IOCFB (inner outer circulating fluidized bed) methods belong to collaborative control technologies based on the SO₂ absorbed by calcium-based sorbents and the dioxins adsorbed by activated carbon. Industrial applications of the four technologies are demonstrated and the removal efficiencies are compared with each other.
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  Mercury Monitoring and Controlling Technologies for Coal Power Plants

  PAN Weiping, ZHANG Yongsheng, LI Wenhan, TENG Yang, WANG Jiawei, LIU Zhao, XU Hong

  Science & Technology Review. 2014, 32(33): 57-60. https://doi.org/10.3981/j.issn.1000-7857.2014.33.007

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  Changing China's energy production and consumption habits has been difficult for a long time, and in a foreseeable future, coal will continue to be the major sector in the production of electricity. Mercury emission during coal combustion is a major anthropogenic source contributing to global mercury emissions. Thus, it is important to monitor and control mercury emissions during coal combustion. In this paper, mercury emission, measurement, and control technologies for coal fired power plants in China are discussed. The development of future mercury monitoring systems and controlling technologies is also addressed. On the aspect of monitoring, it is suggested that high-precision, high-reliability, and low-cost instruments should be developed to meet the need of mercury emission sources in China. On the other hand, the instrument should also be able to handle the high ash and high moisture flue gases typically found in Chinese coal fired power plants.
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  Source and Harm of Air Fine Particulate Matter Pollution and Control Strategies

  ZHAO Shunzheng, YI Honghong, TANG Xiaolong, GAO Fengyu, ZUO Yanran

  Science & Technology Review. 2014, 32(33): 61-66. https://doi.org/10.3981/j.issn.1000-7857.2014.33.008

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  In recent years, atmospheric pollution caused by air fine particulate matter (PM_2.5) happens frequently in most areas of China, which has seriously affected the human body health and industrial production and thus received extensive concern form the whole society. This paper reviews the research progress on the source and harm of air fine particulate matter pollution and control strategies. The primary particulate matter and secondary particulate matters, largely produced by human activity, are the main sources of PM_2.5. When people are constantly exposed to air polluted by PM_2.5, the human respiratory system, cardiovascular system, nervous system and immune system are jeopardized badly. In addition, PM_2.5 could cause a decline in the atmospheric visibility, which will affect the normal production and life. According to the current status of PM_2.5 pollution, comprehensive suggestions for China's PM_2.5 pollution control are put forward.
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  Progress in Analysis of Concentration and Contents of Heavy Metals in Atmosphere Particulate Matter

  GE Liangquan, LIU Hefan, GUO Shengliang, LUO Yaoyao, ZHAO Jiankun

  Science & Technology Review. 2014, 32(33): 67-74. https://doi.org/10.3981/j.issn.1000-7857.2014.33.009

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  The research progress in analysis of concentration of particulate matter and contents of heavy metals in atmosphere at home and abroad is summarized, including the definition of particulate matter in atmosphere, its origin and composition, pathways and hazards, testing equipment and methods, technical standards and so on. The paper also compares the testing equipment and methods and the technical standards at home and abroad. It is shown that our country lags behind in these aspects. It is also pointed that instruments which can automatically and continuously do online testing should be developed at home and abroad.
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  Indoor Ozone Pollution and Purification Technologies

  YI Zhongqin, WANG Yu, TIAN Xiaobing, WANG Xiuyan, JIN Taosheng

  Science & Technology Review. 2014, 32(33): 75-78. https://doi.org/10.3981/j.issn.1000-7857.2014.33.010

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  An increasing number of air pollutants, like haze, have aroused people's great concern about the indoor air quality. Ozone is one of the key factors influencing indoor air quality. In this paper, according to the recent research on indoor ozone pollution at home and abroad, the sources of indoor ozone and indoor pollution are analyzed and reviewed, and some current methods and technologies for ozone purification are discussed. Finally, based on the above presentation, some more efficient and practical multiphase thermal catalysts are suggested to be developed for ozone purification.
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  Impact and Disposal Measures of Radioactive Waste After Fukushima Nuclear Accident

  ZHANG Qiong, WANG Bo, WANG Liang, ZHANG Chunming, LIU Fudong

  Science & Technology Review. 2014, 32(33): 79-86. https://doi.org/10.3981/j.issn.1000-7857.2014.33.011

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  During the Fukushima nuclear accident, a huge amounts of radioactive materials leaked out of the reactor building shell and polluted a large surrounding area. Furthermore, the secondary pollutants produced during the subsequent processing are still active. Therefore, the radioactive wastes in the Fukushima nuclear accident have the characteristics of huge amounts and wide range. It remians a serious challenge to the disposal measures. This paper introduces the environmental pollution after the accident, especially in the site of Fukushima nuclear power plant. The classification, characteristics and disposal measures of the radioactive wastes are analyzed, respectively. Suggestions on disposal measures of radioactive wastes and the inspiration on China's nuclear power development are summarized.
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  Research on 3D Simulation of Air Pollution Diffusion Based on MultiPatch Model

  WU Fengqiang, YANG Wunian, ZHANG Wenjun

  Science & Technology Review. 2014, 32(33): 87-90. https://doi.org/10.3981/j.issn.1000-7857.2014.33.012

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  The pollution concentration distribution in the vertical scale has been paid more and more attention. So, it is greatly significant to research 3D simulation of atmospheric diffusion in environmental monitoring. With 3D GIS, a Gauss pollution diffusion system, which is based on the Gaussian diffusion model and the multiPatch model, is constructed by boundary value calculation, building triangle strip, multipatch interpolating and rendering. The migration process of air pollution and a 3D diffusion model generation algorithm are also introduced. Moreover, the dynamic diffusion process of SO₂ in a factory is simulated by 2D and 3D schemes, based on which the characteristics of spatial distribution are achieved and the maximum landing distance is obtained as 206 m. The practical application of the system shows that the way of 3D simulation based on the multipatch model is effective and suitable for profile computing and spatial analysis in 3D space.