·附件2
论文中英文摘要
作者姓名：赵瑜
论文题目：中国燃煤电厂大气污染物排放及环境影响研究
作者简介：赵瑜，男，1981年10月出生，2003年09月师从于清华大学郝吉明教授，于2008年7月获博士学位。
中 文 摘 要
燃煤电厂是我国大气污染和区域酸沉降控制的重点。开展对燃煤电厂污染物排放水平及其环境影响的研究，对我国未来大气污染控制和能源、环境与社会发展的综合决策具有重要意义。本研究建立了综合排放特征、污染控制情景、空气质量影响和生态风险评价于一体的燃煤电厂污染控制决策方法，对我国燃煤电厂的二氧化硫（SO2）、氮氧化物（NOx）和PM（颗
粒物）排放的时空分布，及其对区域空气质量和生态系统酸化的影响进行了全面的分析和评价。
研究采用以烟气分析仪和低压荷电捕集器（ELPI）为主体的固定源大气污染物排放采样系统，通过现场测试获得全国6个典型电厂9台机组的SO2、NOx和PM的排放特征基础数据
和烟气处理设施的污染控制效果。结果表明，大多数燃用烟煤的煤粉炉的硫释放率在90%-95%之间，循环流化床锅炉在燃煤过程中能够降低约25%的SO2排放，“十一五”期间普遍使用的
湿法脱硫装置（WFGD）对SO2的去除效率可达95%以上。NOx排放水平与燃烧器布置型式和煤
种等因素有关，使用墙式对冲燃烧器和燃用低挥发分煤种更易于炉内NOx的生成。低氮燃烧器（LNB）对NOx生成仅有30%左右的控制效果。燃煤电厂产生的可吸入颗粒物（PM10）的质
量浓度约占总烟尘的9.9%-28.1%；经除尘器作用后，该比例上升至27.9%-83.6%，且质量浓度呈双模态对数正态分布，峰值分别出现在粒径0.2-0.3μm和2.0-3.0μm处。静电除尘器（ESP）对总烟尘去除效率超过99%，但对细微颗粒物（PM2.5）的去除效率较低，约90.9%-96.8%；
WFGD对颗粒物也有一定协同去除作用；各除尘器对PM10的最大穿透率均出现在粒径0.1-1.0μm
范围内。根据现场实测和文献统计结果，本研究建立了涵盖各类机组，具有合理源分类方式的中国燃煤电厂大气污染物排放因子库。按美国AP-42排放因子库的标准，各类机组的NOx排放因子可靠度达到B级，使用ESP的煤粉炉机组的PM排放因子可靠度达到A级。
根据我国燃煤电厂详细调查信息，本研究建立了“基于机组” 的电厂活动水平统计及污染物排放清单研究方法，用以深入揭示锅炉类型、燃烧方式、燃料质量及控制技术对污染物排放特征及地理分布的影响；并基于节能减排政策的需要，使用该方法完成全国煤电行业大气污染物排放清单的测算。2000-2005年，全国燃煤电厂SO2、NOx和PM的排放分别增长了
47%、61%和22%。2005年，全国煤电装机容量约356 GW，电力部门的煤炭消耗量约1069百万吨（Mt），约占全国煤炭消耗总量的49%；SO2、NOx和PM排放总量分别为16097、6965和
2774千吨（kt），分别占全国人为源排放的53%、36%和9%。由于人口密度和经济发展程度对
我国电力建设的布局影响很大，东部、中南、华北和东北地区燃煤电厂的SO2、NOx和PM排
放总量分别占全国煤电行业排放量的78%、84%和85%。预计“十一五”期间，我国电力行业将持续高速发展，燃煤量年均增长率将超过10%。2010年，全国煤电装机容量将达到680 GW，其煤炭消耗量将达到1700 Mt。随着WFGD在全国大型燃煤机组普遍使用以及污染控制技术落后的高能耗机组逐步关停（电力规划情景），2010年全国煤电行业的SO2排放量将下降至11801
kt，WFGD对颗粒物的协同捕集作用使煤电PM的排放也减少至2540 kt，煤电SO2和PM的排放
分别占全国人为源排放总量的42%和10%。与此同时，电厂NOx的排放缺乏相应政策和有效控制，预计2010年全国煤电行业NOx排放量将达到9680 kt，占全国人为源排放的39%。如果关停小火电和“酸雨和二氧化硫控制区”（两控区）政策得到严格执行（电力控制情景），SO2、NOx和PM的排放量将分别进一步下降至7956、9059和1901 kt，分别占全国人为源排放总量的33%、38%和7%。
由于缺乏2010年后全国电力建设详细规划，本研究设置高、中、低三种经济与能源发展情景和基准、参考、强化政策三种污染控制方案，对2010- 2020年全国燃煤电厂的污染物排放趋势进行预测。在不同经济社会发展速度和发电能源清洁化程度的假设下，预计2015和2020年我国煤电发电量分别为4197-4732 TWh和4640-5905 TWh，煤电机组装机分别为823-926 GW和967-1230 GW，耗煤量分别为2009-2281 Mt和2176-2769 Mt。基准方案下，2015和2020年煤电行业的SO2和PM排放量有所上升；但参考方案和强化政策方案下两者排放明显下降，
不同控制方案的力度较能源消耗水平的差异对未来排放总量的影响更大，尤以PM更为明显。中能源情景的参考方案下，2015和2020年的煤电行业的SO2排放量分别为10000和9560 kt；
PM排放量分别为2083和1528 kt。能源消耗水平和控制技术应用率对燃煤电厂的NOx排放影响较为复杂，大部分情景方案下，未来煤电NOx排放将有所增加；中能源情景的参考方案下，2015和2020年煤电NOx排放总量已高于SO2，NOx将取代SO2成为燃煤电厂的首要污染物，控
制形势比较严峻。
本研究选取基于生态系统“剂量-响应”关系的酸沉降临界负荷作为定量评估我国燃煤电厂大气污染物排放造成的环境危害的决策工具。针对我国高盐基阳离子沉降的现状，研究对基于稳态质量平衡（SSMB）的临界负荷理论进行了方法学上的扩展。扩展模式同时动态考虑了大气中硫、氮和盐基阳离子沉降在临界负荷计算中的作用和对生态系统酸化的综合影响，可为区域酸沉降控制提供更合理的削减策略。基于临界负荷的扩展模式，本研究完成了中国硫和氮的临界负荷区划，作为评价全国生态系统酸化风险的指标。
利用区域空气质量模型CMAQ模拟分析电厂大气污染排放造成的环境影响,关注物种包括SO2、NOx和PM10浓度，SO42-、NO3-、总硫和总氮沉降。基准年（2005年)模拟值和监测值的比
对表明，模型对我国东、中南和华北地区城市浓度的模拟结果较好，而对西南、东北和西北地区城市的模拟偏低；在所有物种中，NO3-湿沉降模拟结果最理想。从总体上看，模型结果能
够满足全国尺度上的环境影响研究和控制决策分析的要求。
模拟结果表明，我国电厂排放对SO2浓度贡献最高的地区出现在东北、中南和西南；对
NOx浓度贡献最高出现在东北和华北；对PM10浓度贡献最高出现在中南和西南。总体来看，电
厂排放对浓度的贡献率在北方地区较高，而对沉降的贡献率在南方地区较高。“十一五”期间对电厂实施烟气脱硫效果明显，2010年在电力规划排放情景下，全国大部分地区SO2浓度较
2005年有所下降，南方和西北大部分地区硫沉降也有不同程度的降低；由于缺乏严格的排放控制政策和措施，氮污染有进一步恶化趋势，大部分地区NOx浓度和氮沉降都有所上升，以华北和中南地区最为突出；PM10浓度的变化率相对较小。在电力控制情境下，东北和西南地区
的SO2浓度，以及东部和中南地区的硫沉降下降较为明显；NOx和PM10浓度，以及氮沉降的改
善效果依然较差。
2005年硫的超临界负荷较严重的地区集中在东部、中南和西南地区，而氮的超临界负荷集中在宁夏和内蒙古中部。在2010年电力规划情景下，西南和中南地区硫的超临界负荷情况有所改善，但东部硫沉降超临界负荷依然普遍存在，表明未来我国生态系统酸化风险仍不可忽视。氮的超临界负荷在东部和中南地区趋于严重，并在很大程度上抵消因硫排放削减导致的生态系统酸化改善效果，因此燃煤电厂的NOx排放控制将成为未来我国区域大气污染治理的重要任务。
“十一五”期间以电厂脱硫为主的全国大气污染控制政策将明显减轻区域硫污染；尽管WFGD的广泛应用将会同时降低电厂的颗粒物排放，但由于电厂大多位于郊区，且对颗粒物的排放分担率和浓度贡献均较低，因此仅对电厂实施控制并不能有效解决城市大气颗粒物污染的问题，需在继续完善大型点源排放控制政策的同时，加强对其他重要排放源的管理与控制。从减轻区域酸化风险的角度，大气中碱性颗粒的逐步控制和区域氮污染的恶化对未来SO2排放
削减提出了更高的要求。因此，发展多污染物协同控制理论对未来中国区域大气污染控制的重要意义。
关键词： 燃煤电厂；排放因子；临界负荷；区域酸沉降
Study on Air Pollutant Emission of Coal-fired Power Plants in China
and its Environmental Impacts
Zhao Yu
ABSTRACT
Coal-fired power plant is the main control target of air pollution and regional acid deposition in China. Study on its emission level and environmental impacts can be of significant importance for future air pollution control and comprehensive decision making for energy, environment and society. In this study, an incorporate methodology was developed, combining the emission estimation, control scenario setting, air quality impact and ecology risk assessment, to evaluate the sulfur dioxide (SO2), nitrogen oxide (NOx) and particulate matter (PM) emissions from coal-fired power plants with time and spatial distribution and the corresponding impacts on regional air quality and ecological acidification.
Emission characteristics of SO2, NOx and PM and controlling effects of flue gas purification devices were measured at 9 units of 6 coal-fired power plants in China, with a sampling system
containing gas analyzer and electrical low pressure impactor (ELPI). According to those field tests, the sulfur release percentage for most bituminous coal-fired pulverized boilers ranged 90%-95%. Circulating fluid bed combustion (CFBC) could decrease the SO2 emissions by around 25%. Wet flue gas desulfurization (WFGD), the technology widely applied during 2006-2010 (the period for so called 11th Five Year Plan, 11th FYP), could reach an SO2 removal efficiency of 95%. The NOx emission level is related with the burner and coal type. Compared with tangentially-fired burner, the swirl burner was more liable to create high NOx emission. The removal efficiency of Low NOx burner (LNB) was approximately 30%. Regarding PM emission, the proportion of inhalable PM (PM10) to total PM mass produced by coal-fired power plants ranged 9.9%-28.1%, and that percentage increased to 27.9%-83.6% after the dust collectors. The size distribution of emitted PM10 displayed a bimodal lognormal distribution, with the peaks at 0.2-0.3 µm and 2.0-3.0 µm respectively. The removal efficiency of electrostatic precipitator (ESP) could exceed 99% for total PM but ranged only 90.9%-96.8% for fine PM (PM2.5). WFGD could also have benefits on PM emission control. It is estimated that 0.1-1.0µm was the size fraction where highest penetration rates of PM were found for all the dust collectors. Based on the filed measurement and literature statistics, an emission factor database of Chinese coal-fired power plants was established with reasonable source classification for all types of units. Under the criteria of US AP-42 emission database, the reliability of NOx emission factors for different unit types reached level B, and the reliability of PM emission factors for pulverized units with ESP reached level A.
Based on the detailed survey information of Chinese coal-fired power plants, a “unit-based” methodology for activity level statistics and emission inventory estimation was establised in this study in order to explore the effect of boiler type, combustion type, fuel quality, and emission control technology on pollutant emission characteristics and spatial distribution. With that method, national atmospheric pollutant emission inventory from coal-fired power sector was estimated and used for policy making of the energy saving and emission reduction strategy. During 2000-2005, the SO2, NOx and PM emissions of Chinese coal-fired power sector were estimated to increase by 47%, 61%, and 22% respectively. In 2005, the national installed capacity of coal-fired power plants reached 356 GW, and the coal consumption of power plants was estimated to be 1069 Mt, approximately 49% of national total coal consumption. SO2, NOx and PM emissions from coal-fired power plants were estimated to be 16097, 6965 and 2774 kt respectively in 2005, accounting for 53%, 36%, and 9% of the national anthropogenic emissions respectively. Since the power construction is largely influenced by the population density and economic development, eastern, south-central, north-central, and northeastern China accounted for 78%, 84% and 85% of national power sector emissions of SO2, NOx and PM respectively. It was predicted that the national power sector would keep fast development and the annual increasing rate of coal
consumption by power would exceed 10% during the 11th FYP. In 2010, the installed capacity and coal consumption of coal-fired power sector would reach 680 GW and 1700 Mt respectively. Due to wide application of WFGD and retirement of small, inefficient units (the plan case), SO2 and PM emissions from coal-fired power plants would decrease to 11801 and 2540 kt, accounting for 42% and 10% of the national anthropogenic emissions respectively. Without effective policy and control measures, however, NOx emission from coal-fired power sector would increase to 9680 kt, accounting for 39% of the total national emissions. Through full implementation of phasing out small units and emission control policy in the acid rain and sulfur dioxide control zones (the control case), SO2, NOx and PM emissions from coal-fired power sector would further decrease to 7956, 9059, and 1901 kt, accounting for 33%, 38% and 7% of national anthropogenic emissions respectively.
Since the detailed plans of power construction after 2010 were not available, scenario analysis was applied to evaluate the emission trends of coal-fired power sector during 2010-2020. High, medium and low scenarios for economy and energy development, and base, reference and policy scenarios for emission controls were provided in the study. Under assumptions with different levels for social and economic development and shares of clean power, the electricity generated by coal-fired power plants in 2015 and 2020 was estimated to be 4197-4732 and 4640-5905 TWh respectively; the installed capacity of coal-fired power plants was estimated to be 823-926 and 967-1230 GW respectively; and the coal consumption by power sector was estimated to be 2009-2281 and 2176-2769 Mt respectively. In the base scenarios, SO2 and PM emissions from coal-fired power sector would increase slightly, while considerable emission reduction could be found in the reference and policy scenarios. Compared with the energy consumption level, the emission control measures would have larger impact on the emission levels, particularly for PM. In the medium-reference scenario, the emissions from coal-fired power sector in 2015 and 2020 were estimated to be 10000 and 9560 kt for SO2 respectively, and 2083 and 1528 kt for PM respectively. The influence of energy consumption and emission control on NOx emission would be more complicated. In most scenarios, future NOx emissions by power plants would increase. In the medium-reference scenario, the NOx emission from coal-fired power sector would exceed SO2 and thus become the most important pollutant by the sector instead. That would be a great challenge for Chinese atmospheric pollution control.
Acidifying critical load, which is based on the “dose-response” function of ecosystem, was selected as the decision making tool through quantitative evaluation of the environmental impacts from power sector emissions. Aiming at the extremely high depositions of base cations in China, an extension methodology of the steady status mass balance (SSMB) theory for critical load was developed. Atmospheric sulfur, nitrogen and base cation depositions were simultaneously taken into
account for their ecosystem effects in the critical load calculation, and better emission abatement policy could accordingly be made for regional acidification control. With this new-built model, the critical load maps for sulfur and nitrogen were updated based on former studies, and used as the criterion of ecosystem acidification.
Models-3/Community Multiscale Air Quality (CMAQ) was applied to evaluate the environmental impacts of power plant emissions. SO2, NOx, and PM10 concentrations, and SO42-, NO3-, total sulfur, and total nitrogen depositions, were the most concerned species. The comparisons between monitored and simulated results for the base year (2005) indicated that model simulation could provide good concentration results for eastern, south-central and north-central China but might underestimate the concentrations in southwestern, northeastern and northwestern areas. Among all the species, simulated wet NO3- deposition matched best with the observation data. Generally, the simulation results could satisfy the need of environmental impact analysis and decision making for pollution control at the national level.
According to simulation results, northeastern, south-central and southwestern China received largest contribution by power sector for SO2 concentration, northeastern and north-central for NOx concentration, and south-central and southwestern for PM10. In general, larger contribution of power emissions was found in the north for concentration, and in the south for deposition. The implementation of FGD policy during 11th FYP period would have an effect: under the plan case the SO2 concentrations in most areas, and the sulfur depositions in southern and northwestern China, would be substantially decreased in 2010. However, nitrogen pollution would be exacerbated without strict emission control policy and measures: both NOx concentrations and nitrogen depositions in most areas would increase during the five years, particularly in the north-central and south-central areas. The variation of PM10 in the period would be relatively small. Under the control case, further abatement would be found for SO2 concentrations in northeastern and southwestern China, and sulfur depositions in eastern and south-central China. The NOx and PM10 concentrations and nitrogen depositions would still not be obviously reduced.
In 2005, the areas seriously exceeding sulfur critical load contained eastern, south-central and southwestern China, while nitrogen contained Ningxia and central Inner Mongolia. In the plan case in 2010, the sulfur critical load exceedance in southwestern and south-central would be mitigated, but the wide exceedance in eastern indicated that attention should still be paid on the ecosystem acidification risks in China. The exceedance of nitrogen critical load would become more serious in eastern and south-central China, and could largely counteract the acidification abatement from SO2 emission cutting. Thus NOx emission control of power sectors would become an important task of regional air pollution mitigation in the future.
As the main measure of atmospheric pollution control during the 11th FYP period, the policy
of FGD application on power sector would significantly reduce the regional sulfur pollution, and also cut part of the PM emissions. However, controlling PM emission from power plant separately could not effectively solve the PM pollution in cites, since most power plants are located in suburb and the emission share and concentration contribution of PM by power sector were relatively small. Therefore it is necessary to implement control measures for other important PM emission sources besides for large point sources. In the future, the control of alkaline particles and exacerbation of regional nitrogen pollution could raise pressure to limit acidification through further SO2 abatement. Therefore it is of great significance to develop the multi-pollutant control strategy for Chinese regional air pollution control.
Key words: Coal-fired power plant; emission factor; critical load; regional acid deposition
·附件2
论文中英文摘要
作者姓名：赵瑜
论文题目：中国燃煤电厂大气污染物排放及环境影响研究
作者简介：赵瑜，男，1981年10月出生，2003年09月师从于清华大学郝吉明教授，于2008年7月获博士学位。
中 文 摘 要
燃煤电厂是我国大气污染和区域酸沉降控制的重点。开展对燃煤电厂污染物排放水平及其环境影响的研究，对我国未来大气污染控制和能源、环境与社会发展的综合决策具有重要意义。本研究建立了综合排放特征、污染控制情景、空气质量影响和生态风险评价于一体的燃煤电厂污染控制决策方法，对我国燃煤电厂的二氧化硫（SO2）、氮氧化物（NOx）和PM（颗
粒物）排放的时空分布，及其对区域空气质量和生态系统酸化的影响进行了全面的分析和评价。
研究采用以烟气分析仪和低压荷电捕集器（ELPI）为主体的固定源大气污染物排放采样系统，通过现场测试获得全国6个典型电厂9台机组的SO2、NOx和PM的排放特征基础数据
和烟气处理设施的污染控制效果。结果表明，大多数燃用烟煤的煤粉炉的硫释放率在90%-95%之间，循环流化床锅炉在燃煤过程中能够降低约25%的SO2排放，“十一五”期间普遍使用的
湿法脱硫装置（WFGD）对SO2的去除效率可达95%以上。NOx排放水平与燃烧器布置型式和煤
种等因素有关，使用墙式对冲燃烧器和燃用低挥发分煤种更易于炉内NOx的生成。低氮燃烧器（LNB）对NOx生成仅有30%左右的控制效果。燃煤电厂产生的可吸入颗粒物（PM10）的质
量浓度约占总烟尘的9.9%-28.1%；经除尘器作用后，该比例上升至27.9%-83.6%，且质量浓度呈双模态对数正态分布，峰值分别出现在粒径0.2-0.3μm和2.0-3.0μm处。静电除尘器（ESP）对总烟尘去除效率超过99%，但对细微颗粒物（PM2.5）的去除效率较低，约90.9%-96.8%；
WFGD对颗粒物也有一定协同去除作用；各除尘器对PM10的最大穿透率均出现在粒径0.1-1.0μm
范围内。根据现场实测和文献统计结果，本研究建立了涵盖各类机组，具有合理源分类方式的中国燃煤电厂大气污染物排放因子库。按美国AP-42排放因子库的标准，各类机组的NOx排放因子可靠度达到B级，使用ESP的煤粉炉机组的PM排放因子可靠度达到A级。
根据我国燃煤电厂详细调查信息，本研究建立了“基于机组” 的电厂活动水平统计及污染物排放清单研究方法，用以深入揭示锅炉类型、燃烧方式、燃料质量及控制技术对污染物排放特征及地理分布的影响；并基于节能减排政策的需要，使用该方法完成全国煤电行业大气污染物排放清单的测算。2000-2005年，全国燃煤电厂SO2、NOx和PM的排放分别增长了
47%、61%和22%。2005年，全国煤电装机容量约356 GW，电力部门的煤炭消耗量约1069百万吨（Mt），约占全国煤炭消耗总量的49%；SO2、NOx和PM排放总量分别为16097、6965和
2774千吨（kt），分别占全国人为源排放的53%、36%和9%。由于人口密度和经济发展程度对
我国电力建设的布局影响很大，东部、中南、华北和东北地区燃煤电厂的SO2、NOx和PM排
放总量分别占全国煤电行业排放量的78%、84%和85%。预计“十一五”期间，我国电力行业将持续高速发展，燃煤量年均增长率将超过10%。2010年，全国煤电装机容量将达到680 GW，其煤炭消耗量将达到1700 Mt。随着WFGD在全国大型燃煤机组普遍使用以及污染控制技术落后的高能耗机组逐步关停（电力规划情景），2010年全国煤电行业的SO2排放量将下降至11801
kt，WFGD对颗粒物的协同捕集作用使煤电PM的排放也减少至2540 kt，煤电SO2和PM的排放
分别占全国人为源排放总量的42%和10%。与此同时，电厂NOx的排放缺乏相应政策和有效控制，预计2010年全国煤电行业NOx排放量将达到9680 kt，占全国人为源排放的39%。如果关停小火电和“酸雨和二氧化硫控制区”（两控区）政策得到严格执行（电力控制情景），SO2、NOx和PM的排放量将分别进一步下降至7956、9059和1901 kt，分别占全国人为源排放总量的33%、38%和7%。
由于缺乏2010年后全国电力建设详细规划，本研究设置高、中、低三种经济与能源发展情景和基准、参考、强化政策三种污染控制方案，对2010- 2020年全国燃煤电厂的污染物排放趋势进行预测。在不同经济社会发展速度和发电能源清洁化程度的假设下，预计2015和2020年我国煤电发电量分别为4197-4732 TWh和4640-5905 TWh，煤电机组装机分别为823-926 GW和967-1230 GW，耗煤量分别为2009-2281 Mt和2176-2769 Mt。基准方案下，2015和2020年煤电行业的SO2和PM排放量有所上升；但参考方案和强化政策方案下两者排放明显下降，
不同控制方案的力度较能源消耗水平的差异对未来排放总量的影响更大，尤以PM更为明显。中能源情景的参考方案下，2015和2020年的煤电行业的SO2排放量分别为10000和9560 kt；
PM排放量分别为2083和1528 kt。能源消耗水平和控制技术应用率对燃煤电厂的NOx排放影响较为复杂，大部分情景方案下，未来煤电NOx排放将有所增加；中能源情景的参考方案下，2015和2020年煤电NOx排放总量已高于SO2，NOx将取代SO2成为燃煤电厂的首要污染物，控
制形势比较严峻。
本研究选取基于生态系统“剂量-响应”关系的酸沉降临界负荷作为定量评估我国燃煤电厂大气污染物排放造成的环境危害的决策工具。针对我国高盐基阳离子沉降的现状，研究对基于稳态质量平衡（SSMB）的临界负荷理论进行了方法学上的扩展。扩展模式同时动态考虑了大气中硫、氮和盐基阳离子沉降在临界负荷计算中的作用和对生态系统酸化的综合影响，可为区域酸沉降控制提供更合理的削减策略。基于临界负荷的扩展模式，本研究完成了中国硫和氮的临界负荷区划，作为评价全国生态系统酸化风险的指标。
利用区域空气质量模型CMAQ模拟分析电厂大气污染排放造成的环境影响,关注物种包括SO2、NOx和PM10浓度，SO42-、NO3-、总硫和总氮沉降。基准年（2005年)模拟值和监测值的比
对表明，模型对我国东、中南和华北地区城市浓度的模拟结果较好，而对西南、东北和西北地区城市的模拟偏低；在所有物种中，NO3-湿沉降模拟结果最理想。从总体上看，模型结果能
够满足全国尺度上的环境影响研究和控制决策分析的要求。
模拟结果表明，我国电厂排放对SO2浓度贡献最高的地区出现在东北、中南和西南；对
NOx浓度贡献最高出现在东北和华北；对PM10浓度贡献最高出现在中南和西南。总体来看，电
厂排放对浓度的贡献率在北方地区较高，而对沉降的贡献率在南方地区较高。“十一五”期间对电厂实施烟气脱硫效果明显，2010年在电力规划排放情景下，全国大部分地区SO2浓度较
2005年有所下降，南方和西北大部分地区硫沉降也有不同程度的降低；由于缺乏严格的排放控制政策和措施，氮污染有进一步恶化趋势，大部分地区NOx浓度和氮沉降都有所上升，以华北和中南地区最为突出；PM10浓度的变化率相对较小。在电力控制情境下，东北和西南地区
的SO2浓度，以及东部和中南地区的硫沉降下降较为明显；NOx和PM10浓度，以及氮沉降的改
善效果依然较差。
2005年硫的超临界负荷较严重的地区集中在东部、中南和西南地区，而氮的超临界负荷集中在宁夏和内蒙古中部。在2010年电力规划情景下，西南和中南地区硫的超临界负荷情况有所改善，但东部硫沉降超临界负荷依然普遍存在，表明未来我国生态系统酸化风险仍不可忽视。氮的超临界负荷在东部和中南地区趋于严重，并在很大程度上抵消因硫排放削减导致的生态系统酸化改善效果，因此燃煤电厂的NOx排放控制将成为未来我国区域大气污染治理的重要任务。
“十一五”期间以电厂脱硫为主的全国大气污染控制政策将明显减轻区域硫污染；尽管WFGD的广泛应用将会同时降低电厂的颗粒物排放，但由于电厂大多位于郊区，且对颗粒物的排放分担率和浓度贡献均较低，因此仅对电厂实施控制并不能有效解决城市大气颗粒物污染的问题，需在继续完善大型点源排放控制政策的同时，加强对其他重要排放源的管理与控制。从减轻区域酸化风险的角度，大气中碱性颗粒的逐步控制和区域氮污染的恶化对未来SO2排放
削减提出了更高的要求。因此，发展多污染物协同控制理论对未来中国区域大气污染控制的重要意义。
关键词： 燃煤电厂；排放因子；临界负荷；区域酸沉降
Study on Air Pollutant Emission of Coal-fired Power Plants in China
and its Environmental Impacts
Zhao Yu
ABSTRACT
Coal-fired power plant is the main control target of air pollution and regional acid deposition in China. Study on its emission level and environmental impacts can be of significant importance for future air pollution control and comprehensive decision making for energy, environment and society. In this study, an incorporate methodology was developed, combining the emission estimation, control scenario setting, air quality impact and ecology risk assessment, to evaluate the sulfur dioxide (SO2), nitrogen oxide (NOx) and particulate matter (PM) emissions from coal-fired power plants with time and spatial distribution and the corresponding impacts on regional air quality and ecological acidification.
Emission characteristics of SO2, NOx and PM and controlling effects of flue gas purification devices were measured at 9 units of 6 coal-fired power plants in China, with a sampling system
containing gas analyzer and electrical low pressure impactor (ELPI). According to those field tests, the sulfur release percentage for most bituminous coal-fired pulverized boilers ranged 90%-95%. Circulating fluid bed combustion (CFBC) could decrease the SO2 emissions by around 25%. Wet flue gas desulfurization (WFGD), the technology widely applied during 2006-2010 (the period for so called 11th Five Year Plan, 11th FYP), could reach an SO2 removal efficiency of 95%. The NOx emission level is related with the burner and coal type. Compared with tangentially-fired burner, the swirl burner was more liable to create high NOx emission. The removal efficiency of Low NOx burner (LNB) was approximately 30%. Regarding PM emission, the proportion of inhalable PM (PM10) to total PM mass produced by coal-fired power plants ranged 9.9%-28.1%, and that percentage increased to 27.9%-83.6% after the dust collectors. The size distribution of emitted PM10 displayed a bimodal lognormal distribution, with the peaks at 0.2-0.3 µm and 2.0-3.0 µm respectively. The removal efficiency of electrostatic precipitator (ESP) could exceed 99% for total PM but ranged only 90.9%-96.8% for fine PM (PM2.5). WFGD could also have benefits on PM emission control. It is estimated that 0.1-1.0µm was the size fraction where highest penetration rates of PM were found for all the dust collectors. Based on the filed measurement and literature statistics, an emission factor database of Chinese coal-fired power plants was established with reasonable source classification for all types of units. Under the criteria of US AP-42 emission database, the reliability of NOx emission factors for different unit types reached level B, and the reliability of PM emission factors for pulverized units with ESP reached level A.
Based on the detailed survey information of Chinese coal-fired power plants, a “unit-based” methodology for activity level statistics and emission inventory estimation was establised in this study in order to explore the effect of boiler type, combustion type, fuel quality, and emission control technology on pollutant emission characteristics and spatial distribution. With that method, national atmospheric pollutant emission inventory from coal-fired power sector was estimated and used for policy making of the energy saving and emission reduction strategy. During 2000-2005, the SO2, NOx and PM emissions of Chinese coal-fired power sector were estimated to increase by 47%, 61%, and 22% respectively. In 2005, the national installed capacity of coal-fired power plants reached 356 GW, and the coal consumption of power plants was estimated to be 1069 Mt, approximately 49% of national total coal consumption. SO2, NOx and PM emissions from coal-fired power plants were estimated to be 16097, 6965 and 2774 kt respectively in 2005, accounting for 53%, 36%, and 9% of the national anthropogenic emissions respectively. Since the power construction is largely influenced by the population density and economic development, eastern, south-central, north-central, and northeastern China accounted for 78%, 84% and 85% of national power sector emissions of SO2, NOx and PM respectively. It was predicted that the national power sector would keep fast development and the annual increasing rate of coal
consumption by power would exceed 10% during the 11th FYP. In 2010, the installed capacity and coal consumption of coal-fired power sector would reach 680 GW and 1700 Mt respectively. Due to wide application of WFGD and retirement of small, inefficient units (the plan case), SO2 and PM emissions from coal-fired power plants would decrease to 11801 and 2540 kt, accounting for 42% and 10% of the national anthropogenic emissions respectively. Without effective policy and control measures, however, NOx emission from coal-fired power sector would increase to 9680 kt, accounting for 39% of the total national emissions. Through full implementation of phasing out small units and emission control policy in the acid rain and sulfur dioxide control zones (the control case), SO2, NOx and PM emissions from coal-fired power sector would further decrease to 7956, 9059, and 1901 kt, accounting for 33%, 38% and 7% of national anthropogenic emissions respectively.
Since the detailed plans of power construction after 2010 were not available, scenario analysis was applied to evaluate the emission trends of coal-fired power sector during 2010-2020. High, medium and low scenarios for economy and energy development, and base, reference and policy scenarios for emission controls were provided in the study. Under assumptions with different levels for social and economic development and shares of clean power, the electricity generated by coal-fired power plants in 2015 and 2020 was estimated to be 4197-4732 and 4640-5905 TWh respectively; the installed capacity of coal-fired power plants was estimated to be 823-926 and 967-1230 GW respectively; and the coal consumption by power sector was estimated to be 2009-2281 and 2176-2769 Mt respectively. In the base scenarios, SO2 and PM emissions from coal-fired power sector would increase slightly, while considerable emission reduction could be found in the reference and policy scenarios. Compared with the energy consumption level, the emission control measures would have larger impact on the emission levels, particularly for PM. In the medium-reference scenario, the emissions from coal-fired power sector in 2015 and 2020 were estimated to be 10000 and 9560 kt for SO2 respectively, and 2083 and 1528 kt for PM respectively. The influence of energy consumption and emission control on NOx emission would be more complicated. In most scenarios, future NOx emissions by power plants would increase. In the medium-reference scenario, the NOx emission from coal-fired power sector would exceed SO2 and thus become the most important pollutant by the sector instead. That would be a great challenge for Chinese atmospheric pollution control.
Acidifying critical load, which is based on the “dose-response” function of ecosystem, was selected as the decision making tool through quantitative evaluation of the environmental impacts from power sector emissions. Aiming at the extremely high depositions of base cations in China, an extension methodology of the steady status mass balance (SSMB) theory for critical load was developed. Atmospheric sulfur, nitrogen and base cation depositions were simultaneously taken into
account for their ecosystem effects in the critical load calculation, and better emission abatement policy could accordingly be made for regional acidification control. With this new-built model, the critical load maps for sulfur and nitrogen were updated based on former studies, and used as the criterion of ecosystem acidification.
Models-3/Community Multiscale Air Quality (CMAQ) was applied to evaluate the environmental impacts of power plant emissions. SO2, NOx, and PM10 concentrations, and SO42-, NO3-, total sulfur, and total nitrogen depositions, were the most concerned species. The comparisons between monitored and simulated results for the base year (2005) indicated that model simulation could provide good concentration results for eastern, south-central and north-central China but might underestimate the concentrations in southwestern, northeastern and northwestern areas. Among all the species, simulated wet NO3- deposition matched best with the observation data. Generally, the simulation results could satisfy the need of environmental impact analysis and decision making for pollution control at the national level.
According to simulation results, northeastern, south-central and southwestern China received largest contribution by power sector for SO2 concentration, northeastern and north-central for NOx concentration, and south-central and southwestern for PM10. In general, larger contribution of power emissions was found in the north for concentration, and in the south for deposition. The implementation of FGD policy during 11th FYP period would have an effect: under the plan case the SO2 concentrations in most areas, and the sulfur depositions in southern and northwestern China, would be substantially decreased in 2010. However, nitrogen pollution would be exacerbated without strict emission control policy and measures: both NOx concentrations and nitrogen depositions in most areas would increase during the five years, particularly in the north-central and south-central areas. The variation of PM10 in the period would be relatively small. Under the control case, further abatement would be found for SO2 concentrations in northeastern and southwestern China, and sulfur depositions in eastern and south-central China. The NOx and PM10 concentrations and nitrogen depositions would still not be obviously reduced.
In 2005, the areas seriously exceeding sulfur critical load contained eastern, south-central and southwestern China, while nitrogen contained Ningxia and central Inner Mongolia. In the plan case in 2010, the sulfur critical load exceedance in southwestern and south-central would be mitigated, but the wide exceedance in eastern indicated that attention should still be paid on the ecosystem acidification risks in China. The exceedance of nitrogen critical load would become more serious in eastern and south-central China, and could largely counteract the acidification abatement from SO2 emission cutting. Thus NOx emission control of power sectors would become an important task of regional air pollution mitigation in the future.
As the main measure of atmospheric pollution control during the 11th FYP period, the policy
of FGD application on power sector would significantly reduce the regional sulfur pollution, and also cut part of the PM emissions. However, controlling PM emission from power plant separately could not effectively solve the PM pollution in cites, since most power plants are located in suburb and the emission share and concentration contribution of PM by power sector were relatively small. Therefore it is necessary to implement control measures for other important PM emission sources besides for large point sources. In the future, the control of alkaline particles and exacerbation of regional nitrogen pollution could raise pressure to limit acidification through further SO2 abatement. Therefore it is of great significance to develop the multi-pollutant control strategy for Chinese regional air pollution control.
Key words: Coal-fired power plant; emission factor; critical load; regional acid deposition