Transport Characteristic Of Pollutants Emitted From Coal-fired Power Plants In Fenwei Plain Area Using WRF And CALPUFF Model

The Fenwei Plain was one of the most serious contaminated area in our country.The proportion of coal consumption in the Fenwei Plain region total coal consumption was close to 90%,and coal consumption for power generation was the largest part in the total coal consumption.Coal-fired power plant,as an elevated point source.The pollutants emitted from coal-fired power plants under the action of meteorological conditions were undergoing advection transmission,turbulence diffusion,secondary transformation,dry and wet settlement and other processes in the upper air,which would affected the air quality of the Fenwei Plain region.To study the transmission process and characteristics of elevated source pollutants emitted from coal-fired power plants has significant guidance for regional air pollution control,haze reduction and joint prevention and control.Based on WRF/CALPUFF model,47 coal-fired power plants with an installed capacity of≥300MW were selected in this paper to study the transmission process of pollutant emitted from these plants in the Fenwei Plain and analyze the transmission characteristics and concentration of pollutants.The main conclusions were as follows:（1）In 2017,the total emissions of SO₂,NO_X,PM₁₀and PM_2.5from the Fenwei Plain coal-fired power plants（≥300MW）were 11057.45t,21145.95t,1896.90t and 955.80t,respectively.Among which,the emissions of SO₂,NO_X,PM₁₀and PM_2.5in Guanzhong area account for 37.58%,39.34%,49.87%and 49.87%respectively of the total emissions in the Fenwei Plain.The proportions of pollutants in Shanxi area were 43.57%,41.28%,36.14%and36.14%,respectively.The proportions of pollutants in Henan area were 18.85%,19.37%,14.01%and 14.01%,respectively.（2）The average wind speed at the height of 10m near the ground of Fenwei Plain was less than 3.00m/s,300m was less than 6.00m/s,with variable wind direction in Fenwei Plain.In January（representing winter）,counterclockwise cyclone was exist in Guanzhong area under the influence of the terrain at a height of 10m.At the height of 300m（the height of effective emissions from coal-fired power plants）,there was exists significant counterclockwise cyclone in most parts of Guanzhong Basin.Pollutants emitted from coal-fired power plants in Shanxi and Henan regions of the Fenwei Plain would have a comprehensive effect in Tongchuan and Weinan cities.In July（representing summer）,the dominant wind direction was the northeast wind in the Fenwei Plain,and the pollutants emitted by coal-fired power plants in Shanxi and Henan areas of the Fenwei Plain were transmitted to the Guanzhong Basin.（3）In Winter,the average daily concentrations of SO₂,NO_X,primary PM₁₀,primary PM_2.5,total PM_2.5,SO₄^2-and NO₃^-emitted from coal-fired power plants in the Fenwei Plain area were 0.111μg/m³,0.166μg/m³,0.057μg/m³,0.016μg/m³,0.094μg/m³,0.010μg/m³and0.057μg/m³,respectively.Among them,primary PM_2.5concentration accounted for only17.02%of the total PM_2.5concentration,while SO₄^2-and NO₃^-（secondary components）accounted for 10.64%and 60.64%,respectively.（4）The maximum concentrations of SO₂,NO_X,primary PM₁₀,primary PM_2.5,total PM_2.5,SO₄^2-and NO₃^-in the Fenwei Plain emitted from Coal fired power plants were 0.95g/m³,1.24μg/m³,0.24μg/m³,0.12μg/m³,0.21μg/m³,0.02μg/m³and 0.11μg/m³,respectively.Emissions from coal-fired power plants have the greatest impact on Guanzhong cities.The high concentration of pollutants in Guanzhong area was concentrated at Xi’an and Xianyang,with significant inter-city transmission.The high concentration of pollutants in Shanxi area was concentrated in Linfen,Lvliang and Jinzhong valleys and was transmitted along the Fenhe Basin.The high pollutant concentration in Henan area were mainly located in the Northeast Sanmenxia and Luoyang cities.（5）In most of Fenwei Plain citis,the PM_2.5concentration emitted from coal-fired power plants（≥300MW）were mainly secondary pollutant,and the proportion of NO₃^-in secondary particles was the largest,with the average proportion ranging from 36.89%to 51.63%.The average proportion of SO₄^2-and NO₃^-in PM_2.5concentration in 11 cities ranged from 53.34%to 66.87%.（6）In winter,among the contribution of Fenwei Plain coal-fired power plant（≥300MW）emissions to NO_X,primary PM₁₀,primary PM_2.5and NO₃^-concentration,the most affected city by regional transmission were Yuncheng,and the contribution rate of each pollutant transmission was 74%,77%,67%and 71%,respectively.Among the contributions of emissions from coal-fired power plants to SO₂,SO₄^2-and PM_2.5in various cities,Sanmenxia has the most significant impact from regional transmission,with the transmission contribution rate being 70%,67%and 77%,respectively.The results above could provide reference basis for the integrated decision making and joint prevention and control of coal-fired power plants in three provinces,and also could provide theoretical support for the emission reduction of elevated sources of coal-fired power plants.