Ash and deposit formation from oxy-coal combustion in a 100 kW test furnace

Ash deposition is still an unresolved problem when retrofitting existing air-fired coal power plants to oxy-fuel combustion. Experimental data are quite necessary for mechanism validation and model development. This work was designed to obtain laboratory combustor data on ash and deposits from oxy-coal combustion, and to explore the effects of oxy-firing on their formation. Two bituminous coals (Utah coal and Illinois coal) and one sub-bituminous coal (PRB coal) were burned on a down-fired combustor under both oxy- and air-firing. Two oxy-fired cases, i.e., 27 vol% O₂/73 vol% CO₂ and 32 vol% O₂/68 vol% CO₂, were selected to match the radiation flux and the adiabatic flame temperature of air combustion, respectively. Once-through CO₂ was used to simulate fully cleaned recycled flue gas. The flue gas excess oxygen was fixed at 3 vol%. For each case, both size-segregated fly ash and bulk fly ash samples were obtained. Simultaneously, ash deposits were collected on an especially designed un-cooled deposition probe. Ash particle size distributions and chemical composition of all samples were characterized. Data showed that oxy-firing had insignificant impacts on the tri-modal ash particle size distributions and composition size distributions in the size range studied. Bulk ash compositions also showed no significant differences between oxy- and air-firing, except for slightly higher sulfur contents in some oxy-fired ashes. The oxy-fired deposits were thicker than those from air-firing, suggesting enhanced ash deposition rates in oxy-firing. Oxy-firing also had apparent impacts on the deposit composition, especially for those components (e.g., CaO, Fe₂O₃, SO₃, etc.) that could contribute significantly to ash deposition. Based on these results, aerodynamic changes in gas flow and changes in combustion temperature seemed more important than chemical changes of ash particles in determining deposit behavior during oxy-coal combustion.     

An investigation into the likely impact of oxy-coal retrofit on fire-side corrosion behavior in utility boilers

Real-time electrochemical measurements of corrosion rate were performed to evaluate the respective corrosion rates of one boiler waterwall material (SA210) and three boiler superheater materials (T22, P91 and 347H) while firing Utah Western bituminous, Illinois high-sulfur bituminous and Powder River Basin (PRB) sub-bituminous coals in a 1.5 MW pulverized coal-fired furnace. The raw average measured corrosion rates were very low, between 0.0003 and 0.016 mm/year (0.012 and 0.63 mils/year) for most materials under air- and oxy-fired conditions. For some high-sulfur conditions measured corrosion rates were as high as 0.72 mm/year (28 mils/year). Waterwall corrosion rates decreased consistently when converting from air- to oxy-firing while superheater corrosion rates generally increased, although they were less than twice the air-fired rate under most conditions. Corrosion rates for the lower alloyed materials (SA210 and T22) increased significantly during transients from reducing to oxidizing conditions. Measured increases in the corrosion rate of 347H material under high sulfur and low temperature conditions, and associated decrease in corrosion rate at higher temperatures on this alloy, were consistent with the formation of trisulphates in the superheater deposits. The increase of corrosion rate with increased metal temperatures was demonstrated, as was the consistently repeatable nature of the observed results.     

SO2 Dispersion and Monthly Evaluation of the Industrial Source Complex Short-Term (ISCST32) Model at Mina Al-Fahal Refinery,Sultanate of Oman

Modeling of air pollutant dispersion has been undertaken for emissions of sulfur dioxide (SO₂) at the Mina Al-Fahal refinery in the Sultanate of Oman. The study was conducted during the period of November 1999 to October 2000. The Industrial Source Complex Short-Term (ISCST32) air pollution model was adopted to predict the ground level concentration of SO₂ in and around the refinery. The modeling results were validated against measured data during the study period. The comparison, based on the monthly average measurements, showed that the model underestimates the observed SO₂ concentrations. However, the predicted ground level concentrations of SO₂ during the months of September, October, November, and June were in better agreement with the observations. The predicted SO₂ values are presented in the form of concentration contours to determine the spatial distribution of SO₂ and to assess the impact on air quality over the survey area. Predicted SO₂ concentrations were found lower than the World Health Organisation (WHO) guideline value of 365 μg/m³, with the maximum ground level concentrations being found to occur relatively close to the sources of emission. Moreover, concentration contour patterns for the modeled area vary with changes in meteorological conditions. On the basis of this study, the refinery is not likely to cause any significant deterioration in air quality, and predicted concentrations of SO₂ are well below those likely to influence health.     

Principles for retrofitting coal burners for oxy-combustion

Experiments were performed in a 1.5 MW pilot-scale furnace to investigate the differences between air- and oxy-fired flame behavior from a pulverized coal oxy-research burner designed for flexible operating conditions. The flame behavior was characterized by recording video images of the flames and by measuring radiation intensity along the flame length. Various strategies relating air- and oxy-fired operation of the burner primary register were investigated where the oxy-fired burner primary mass, momentum and velocity were matched to the air-fired conditions. Matching either burner primary mass or momentum under oxy-fired conditions with air-fired conditions resulted in a flame stabilized within the quarl. Matching primary velocity with air-fired conditions resulted in a detached flame indicating a delay in flame ignition for the oxyfired conditions. A decrease in primary velocity of 13% was necessary in order to stabilize a flame within the quarl similar to the air-fired case. Additional experiments also showed a flame could be stabilized with no oxygen enrichment of the primary (～3 vol.%, dry O₂ in the primary). Experiments where oxygen was injected at the burner face indicated injection at the boundary of the primary and secondary flow paths strongly attach a flame and injection at the coal rich primary flow path increased the radiative intensity of the flame.     

A Review on the Present Scenario of Air Quality Associated with Indian Mining Operations

Compositional changes to air quality from coal mining are not only the most visible impact from these activities on the environment, they can also immediately affect the health of mine professionals and adjoining populations. The presence of gases and suspended solids emitted by mining activities affects the human respiratory system and decreases production in mines. This article summarizes a case study of several Northern Coalfields Limited (NCL) coal mines with an emphasis on particulate matter (PM) to report the status of air quality connected to coal production and overburden removal. The concentrations of sulfur dioxide (SO₂), nitrogen oxides (NO_x), and suspended particulate matter (SPM) reported in the literature are also summarized in table form to allow comparisons to the permissible standards set by the Indian Central Pollution Control Board (CPCB) and other standards used around the world. An up‐to‐date status of air quality at coal mines is compared for mines located in different parts of India. Subsequently, all coal mines were divided into different classes in regard to the severity of their emissions. These classes are, in increasing order of severity, green, yellow, red, and black. SPM measurements were tabulated in regard to concentration and composition. Our article concludes with the recommendation that an environmental impact assessment (EIA) to be conducted to better characterize changes in the environment from mining emissions to develop integrated mitigation measures and to identify additional parameters to define air quality at mines.     

京津冀地区重点耗煤行业大气污染物排放清单研究

本研究通过京津冀地区各行业的年度煤炭消费量确定火电行业、钢铁行业和焦化行业为重点耗煤行业,以在线监测数据、污染源调查(现场调研、环评、验收)数据、排放因子数据为基础,自下而上建立了2013年京津冀地区重点耗煤行业大气污染物排放清单,分析研究了SO_2、NO_x和PM_(10)的排放量与污染贡献分布情况,掌握了京津冀地区重点耗煤行业大气污染物排放现状,为大气污染物减排提供数据基础。研究表明,2013年京津冀火电、钢铁焦化行业共排放SO_2 72.35万t、NO_x 131.99万t、PM_(10) 30.36万t。     

Quantifying the sources of ozone, fine particulate matter, and regional haze in the Southeastern United States

A detailed sensitivity analysis was conducted to quantify the contributions of various emission sources to ozone (O₃), fine particulate matter (PM_2.5), and regional haze in the Southeastern United States. O₃ and particulate matter (PM) levels were estimated using the Community Multiscale Air Quality (CMAQ) modeling system and light extinction values were calculated from modeled PM concentrations. First, the base case was established using the emission projections for the year 2009. Then, in each model run, SO₂, primary carbon (PC), NH₃, NO_x or VOC emissions from a particular source category in a certain geographic area were reduced by 30% and the responses were determined by calculating the difference between the results of the reduced emission case and the base case.The sensitivity of summertime O₃ to VOC emissions is small in the Southeast and ground-level NO_x controls are generally more beneficial than elevated NO_x controls (per unit mass of emissions reduced). SO₂ emission reduction is the most beneficial control strategy in reducing summertime PM_2.5 levels and improving visibility in the Southeast and electric generating utilities are the single largest source of SO₂. Controlling PC emissions can be very effective locally, especially in winter. Reducing NH₃ emissions is an effective strategy to reduce wintertime ammonium nitrate (NO₃NH₄) levels and improve visibility; NO_x emissions reductions are not as effective. The results presented here will help the development of specific emission control strategies for future attainment of the National Ambient Air Quality Standards in the region.     

Environment and productivities in developed and developing countries: The case of carbon dioxide and sulfur dioxide

We propose a productivity index for undesirable outputs such as carbon dioxide (CO₂) and sulfur dioxide (SO₂) emissions and measure it using data from 51 developed and developing countries over the period 1971–2000. About half of the countries exhibit the productivity growth. The changes in the productivity index are linked with their respective per capita income using a semi-parametric model. Our results show technological catch up of low-income countries. However, overall productivities both of SO₂ and CO₂ show somewhat different results.     

NITRATE CONCENTRATIONS IN ILLINOIS RIVERS 1967 TO 1974: COMPARISON AMONG REPORTING AGENCIES1

ABSTRACT: Long term data on surface water quality can sometimes be assembled by combining data collected by different agencies at different times and assuming that between agency differences in data quality are insignificant. The objective of this paper was to assess the quality of riverine nitrate (NO₃) concentrations in Illinois measured and reported by four agencies from 1967 to 1974 by comparing median values for similar sampling locations and periods. A total of 17 river reaches were identified for which two agencies reported NO₃ concentrations during similar periods. Nonparametric comparison of median values and analysis of covariance with discharge as a covariant produced similar results. Nitrate concentrations reported by the U.S. Geological Survey (USGS) from 1967 to 1971 were not statistically (P > 0.05) different from values reported by the Illinois State Water Survey (ISWS) for two of three river reaches. Additionally, NO₃ concentrations reported by USGS from 1972 to 1974 were not statistically different than concentrations reported by the Illinois Environmental Protection Agency (IEPA) for four of five river reaches. From 1969 to 1971, NO₃ concentrations reported by the Illinois Department of Public Heath and the Illinois Environmental Protection Agency (IDPH/IEPA) were less than one‐fourth the magnitude of values reported by ISWS. The median NO₃ concentrations measured by the Central Illinois Public Service (CIPS) were significantly greater than those measured by USGS and IDPH/IEPA in the three comparable sampling locations. The use of NO₃ concentrations measured by CIPS and IDPH/IEPA prior to 1972 is not recommended.     

Assessing the current practice and policy with recommendations for emission control strategy for coal‐fired thermal power plants under Indian regulatory framework emphasizing the roles of R&D

On December 7, 2015, the Ministry of Environment, Forest and Climate Change (MoEFCC), Government of India (GoI), promulgated stack emission standards for sulfur dioxide (SO₂), oxides of nitrogen (NO_x), and mercury (Hg) from coal‐fired thermal power plants (TPPs). These standards were promulgated in addition to tightening the emission standard for particulate matter. Thus far, the GoI and a non‐governmental organization (NGO) have recommended the use of limestone‐based flue‐gas desulfurization (FGD) technology for removing only SO₂ emissions, which would then require the application of additional technologies to remove the other regulated pollutants. A single technology, such as the Multi‐pollutants Control Technology (MPCT), which was recently developed elsewhere in the world and can remove all of the pollutants from the TPP, could be more economical than introducing separate technologies for the removal of each pollutant. Furthermore, unlike the limestone‐based FGD technology, which generates carbon dioxide (CO₂) during the desulfurization process, the MPCT does not increase power plant CO₂ emissions. Water consumption is also lower in MPCT than with the limestone‐based FGD technology. Thus, MPCT offers a lower carbon footprint as well as a lower water footprint than the limestone‐based FGD technology in accordance with the United Nations Environmental Programme's Sustainable Development Goals. In light of these observations, this article aims to assess current practices and policies and offers policy recommendations for Indian TPPs with the goal of providing a cogent technological solution that also strengthens the Decision Support System for the holistic protection of the Indian environment.     

Urban air pollution and atmospheric diffusion research in China

Air pollution has become a serious problem in China as a result of that country's efforts in the last 30 years to become a great industrial power. The burning of coal, which currently provides over 70% of all China's energy needs, is a major source of air pollution. Because Chinese coal is high in sulfur and ash content and because most combustion devices in China have low efficiencies, SO₂ and particulate emissions are a serious problem and are comparable to or exceed those found in many countries that are much more industrialized. Although most coal is burned in North China, acid precipitation is most severe in South China because of the lack of buffering loess dust found in the former region.The Chinese government has already taken major steps to mitigate air pollution, such as relocating polluting industries, supplying coal with lower sulfur content, using gas instead of coal for residential heating, and levying fines on industries that exceed pollution standards. Atmospheric environmental impact assessment (AEIA) is also required for all major new projects. This article describes three types of mathematical diffusion models and field and wind-tunnel experiments that are used in such assessments.The Chinese authorities believe that a range of technological, managerial, locational, and behavioral changes must be effected before the air of Chinese cities can be significantly improved.     

Temporal‐spatial variations of air pollutants in Lanzhou,Gansu Province,China, during the spring–summer periods, 2014–2016

In this article, we analyzed the mass concentrations of particulate matter 2.5 micrometers (µm) or less in size (PM_2.5), particulate matter 10 µm or less in size (PM₁₀), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and ozone (O₃) in Lanzhou, the capital of Gansu province, China. We analyzed monitoring data collected from five air quality monitoring stations during the spring–summer period from 2014 to 2016. Our comparison of contaminant concentrations and average diurnal, daily, monthly, and annual concentrations revealed that the average concentrations of PM_2.5 and PM₁₀ amounted to 128.57 and 46.4 micrograms per cubic meters (µg/m³), respectively, exceeding the Chinese National Ambient Air Quality Standard (NAAQS). We used the Pearson correlation coefficient to establish connections between particulate matter and gaseous pollutants. The results show significant differences in the concentration levels of airborne pollutants. The Pearson correlation coefficient between PM_2.5 and PM₁₀ had the highest coefficient of r = 0.842. A correlation between the two particulate matter sizes (PM_2.5 and PM₁₀) and SO₂ was PM_2.5 and SO₂ r = 0.313; PM₁₀ and SO₂ r = 0.279; and CO and the two particulate matter sizes, PM_2.5 and CO r = 0.304; and PM₁₀ and CO r = 0.203. The average monthly ratio for the study months of PM_2.5 to PM₁₀ was 0.361. In addition, we used the hybrid single particle Lagrangian integrated trajectory model for tracking sources and pathways of the air pollutants in Lanzhou.     

基于产业链分析的长三角地区CO2与大气污染物排放研究

长三角地区作为我国大气污染较为严重区域之一,如何在保持经济增长的同时减少CO₂与大气污染物的排放已成为一个重要挑战。本研究基于2007年与2012年长三角区域间投入产出表,定量分析了长三角地区省市间贸易引致的二氧化碳和大气污染物排放转移特征和变化趋势。同时,运用产业关联系数法,从前向关联与后向关联双重视角分析了长三角地区减缓CO₂和大气污染物排放的关键行业。研究结果表明,长三角的SO₂、PM_2.5排放总量表现为消费端大于生产端,CO₂、NO_x排放总量表现为生产端大于消费端。安徽省总体呈现为长三角地区贸易的SO₂、NO_x与PM_2.5排放净调出地,而上海与浙江表现为多数污染物排放净调入地。CO₂与大气污染物协同前向减排的关键行业为江苏省、浙江省和安徽省的电力、热力的生产和供应业,安徽省的煤炭开采和洗选业等,可以通过生产端技术革新和能源结构优化来促进减排;CO₂与大气污染物后向协同减排的关键行业为江苏省、浙江省和安徽省的建筑业等,对于这些行业,调整消费结构是有效的减排措施。为更好地制定长三角地区减排与污染防治政策,应当综合考虑行业减排、协同减排等,以确保经济持续增长的同时达到减排目标。     

Purification of oxyfuel-derived CO2

Oxyfuel combustion in a pulverised fuel coal-fired power station produces a raw CO₂ product containing contaminants such as water vapour plus oxygen, nitrogen and argon derived from the excess oxygen for combustion, impurities in the oxygen used, and any air leakage into the system. There are also acid gases present, such as SO₃, SO₂, HCl and NO_x produced as byproducts of combustion. At GHGT8 (White and Allam, 2006) we presented reactions that gave a path-way for SO₂ to be removed as H₂SO₄ and NO and NO₂ to be removed as HNO₃. In this paper we present initial results from the OxyCoal-UK project in which these reactions are being studied experimentally to provide the important reaction kinetic information that is so far missing from the literature. This experimental work is being carried out at Imperial College London with synthetic flue gas and then using actual flue gas via a sidestream at Doosan Babcock's 160 kW coal-fired oxyfuel rig. The results produced support the theory that SO_x and NO_x components can be removed during compression of raw oxyfuel-derived CO₂ and therefore, for emissions control and CO₂ product purity, traditional FGD and deNO_x systems should not be required in an oxyfuel-fired coal power plant.     

Life cycle assessment of a pulverized coal power plant with post-combustion capture, transport and storage of CO2

In this study the methodology of life cycle assessment has been used to assess the environmental impacts of three pulverized coal fired electricity supply chains with and without carbon capture and storage (CCS) on a cradle to grave basis. The chain with CCS comprises post-combustion CO₂ capture with monoethanolamine, compression, transport by pipeline and storage in a geological reservoir. The two reference chains represent sub-critical and state-of-the-art ultra supercritical pulverized coal fired electricity generation. For the three chains we have constructed a detailed greenhouse gas (GHG) balance, and disclosed environmental trade-offs and co-benefits due to CO₂ capture, transport and storage. Results show that, due to CCS, the GHG emissions per kWh are reduced substantially to 243 g/kWh. This is a reduction of 78 and 71% compared to the sub-critical and state-of-the-art power plant, respectively. The removal of CO₂ is partially offset by increased GHG emissions in up- and downstream processes, to a small extent (0.7 g/kWh) caused by the CCS infrastructure. An environmental co-benefit is expected following from the deeper reduction of hydrogen fluoride and hydrogen chloride emissions. Most notable environmental trade-offs are the increase in human toxicity, ozone layer depletion and fresh water ecotoxicity potential for which the CCS chain is outperformed by both other chains. The state-of-the-art power plant without CCS also shows a better score for the eutrophication, acidification and photochemical oxidation potential despite the deeper reduction of SO_x and NO_x in the CCS power plant. These reductions are offset by increased emissions in the life cycle due to the energy penalty and a factor five increase in NH₃ emissions.     

长沙市空气自动站周边区域大气污染物排放源清单

以长沙市空气自动站周边3 km为研究对象,基于统计年鉴和实地调查,获得了该地区2015年储存运输源、废弃物处理源、工艺过程源、化石燃料固定燃烧源、农业源、生物质燃烧源、扬尘源、移动源8个源类的活动水平数据。以大气污染物排放源清单编制技术指南为依据,建立了2015年长沙市空气自动站周边3 km区域NH_3、NO_x、PM_(10)、PM_(2.5)、SO_2、VOCs等6项污染物的源排放清单。结果表明,2015年长沙空气自动站周边3 km内,8类大气污染源排放的NH_3、NO_x、PM_(2.5)、PM_(10)、SO_2、VOCs总量分别为53.65t、4 899.35t、1 846.09t、6 257.75t、989.49t、4 383.31t。NH_3、NO_x、PM_(2.5)、PM_(10)、SO_2、VOCs排放量最大的源分别是农业源、移动源、扬尘源、扬尘源、化石燃料固定燃烧源和移动源,贡献率分别为98.45%、84.24%、60.82%、85.90%、97.33%、49.88%。优化道路交通、减少燃煤、减少建筑工地扬尘排放可促进长沙市空气自动站周边空气质量改善。     

Historical Analysis of SO<Subscript>2</Subscript> Pollution Control Policies in China

Coal is not only an important energy source in China but also a major source of air pollution. Because of this, China’s national sulfur dioxide (SO₂) emissions have been the highest in the world for many years, and since the 1990s, the territory of China’s south and southwest has become the third largest acid-rain-prone region in the world. In order to control SO₂ emissions, the Chinese government has formulated and promulgated a series of policies and regulations, but it faces great difficulties in putting them into practice. In this retrospective look at the history of SO₂ control in China, we found that Chinese SO₂ control policies have become increasingly strict and rigid. We also found that the environmental policies and regulations are more effective when central officials consistently give environmental protection top priority. Achieving China’s environmental goals, however, has been made difficult by China’s economic growth. Part of this is due to the practice of environmental protection appearing in the form of an ideological “campaign” or “storm” that lacks effective economic measures. More recently, better enforcement of environmental laws and regulations has been achieved by adding environmental quality to the performance assessment metrics for leaders at all levels. To continue making advances, China needs to reinforce the economic and environmental assessments for pollution control projects and work harder to integrate economic measures into environmental protection. Nonetheless, China has a long way to go before economic growth and environmental protection are balanced.     

Impacts on air pollution in urban areas

Environmental management involves controlling various forms of pollution to levels that do not pose a threat to the health of the people and the environment in general. This paper presents a framework to analyze sources of local air pollution in cities. Using an OLS model, an investigation is performed of the relationship among the concentrations of air pollutants [more precisely, concentrations of sulfur dioxide (SO₂), dust, nitric oxide (NO), nitrogen dioxide (NO₂), carbon oxide (CO) and ozone (O₃)], economic activities, and meteorology. Time series analysis leads to a model, that explains a high degree of the variance in the air pollution data. The model is applied to daily time series from three measurement stations in innsbruck, Austria. Estimation results of the model generally fit with the expected relations. Space heating influences SO₂, dust, and NO, while NO₂ levels are primarily affected by traffic. These results also indicate interdependent relations among the pollutants NO, NO₂, O₃, and CO; O₃ levels depend on temperature and sunshine.     

A novel process integration,optimization and design approach for large-scale implementation of oxy-fired coal power plants with CO2 capture

The widespread use of fossil fuels within the current energy infrastructure is considered as the largest source of anthropogenic emissions of carbon dioxide, which is largely blamed for global warming and climate change. At the current state of development, the risks and costs of non-fossil energy alternatives, such as nuclear, biomass, solar, and wind energy, are so high that they cannot replace the entire share of fossil fuels in the near future timeframe. Additionally, any rapid change towards non-fossil energy sources, even if possible, would result in large disruptions to the existing energy supply infrastructure. As an alternative, the existing and new fossil fuel-based plants can be modified or designed to be either “capture” or “capture-ready” plants in order to reduce their emission intensity through the capture and permanent storage of carbon dioxide in geological formations. This would give the coal-fired power generation units the option to sustain their operations for longer time, while meeting the stringent environmental regulations on air pollutants and carbon emissions in years to come.Currently, there are three main approaches to capturing CO₂ from the combustion of fossil fuels, namely, pre-combustion capture, post-combustion capture, and oxy-fuel combustion. Among these technology options, oxy-fuel combustion provides an elegant approach to CO₂ capture. In this approach, by replacing air with oxygen in the combustion process, a CO₂-rich flue gas stream is produced that can be readily compressed for pipeline transport and storage. In this paper, we propose a new approach that allows air to be partially used in the oxy-fired coal power plants. In this novel approach, the air can be used to carry the coal from the mills to the boiler (similar to the conventional air-fired coal power plants), while O₂ is added to the secondary recycle flow as well as directly to the combustion zone (if needed). From a practical point of view, this approach eliminates problems with the primary recycle and also lessens concerns about the air leakage into the system. At the same time, it allows the boiler and its back-end piping to operate under slight suction; this avoids the potential danger to the plant operators and equipment due to possible exposure to hot combustion gases, CO₂ and particulates. As well, by integrating oxy-fuel system components and optimizing the overall process over a wide range of operating conditions, an optimum or near-optimum design can be achieved that is both cost-effective and practical for large-scale implementation of oxy-fired coal power plants.     

中国煤炭消费对PM2.5污染的影响研究

国务院颁布的《大气污染防治行动计划》明确提出制定国家煤炭消费总量中长期控制目标,到2017年,煤炭占能源消费总量比重降低到65%以下,然而煤炭消费对PM_(2.5)污染的贡献到底多大,这是当前亟待研究的科学问题。为定量分析煤炭消费对我国PM_(2.5)污染的影响,本研究首先计算了2012年煤炭消费产生的大气污染物排量,然后利用CAMx空气质量模型,分别采用组分分析法和情景模拟法两种方法研究了煤炭消费对全国PM_(2.5)污染的影响。组分分析法研究表明,煤炭消费对全国PM_(2.5)年均浓度的贡献率约为61%,其中煤炭直接燃烧、煤炭相关行业的贡献率分别约为37%、24%;情景模拟法研究表明,煤炭消费对全国PM_(2.5)年均浓度的贡献率约为56%。因此,我国由于煤炭消费对全国PM_(2.5)年均浓度的贡献率为56%~61%。