| The Development of Lanzhou Xigu petrochemical concentration district has not only provide an important boost to regional economic growth, but also resulted in obvious environmental issues of which the most prominent is atmospheric environmental issues. How to solve the atmospheric environmental issues effectively in Xigu petrochemical concentration district have become major issues which Xigu surrounding villagers and Lanzhou City leaders concerned.This paper analyses the air pollution index in Lanzhou of 2012 and corresponding meteorological conditions, and collects Xigu petrochemical concentration district’s regional atmospheric status monitoring data of heating period in 2005,2008,2012 and 2014. Analyses the characteristics of changes of air quality in the region in recent ten years, uses the ground concentration reverse calculation method to work out unorganized source of typical pollutants in Xigu petrochemical concentration district, and uses Aermod Models to predict effects of typical pollutants on regional sensitive points, with heavy pollution weather conditions in Lanzhou City. Sets up immediate, mid-term and long-term air quality control programs according to air quality standards, and puts forward corresponding immediate, mid-term and long-term measures to reduce emissions for part of the main typical pollutant discharge device of Xigu petrochemical concentration district. Hope to provide reference for the regional atmospheric environmental control of Xigu petrochemical concentration district..By studying this paper, get the following conclusions:Firstly, In 2012, Lanzhou City’s air quality pollution days are 95 days, accounting for 26.03% of the year. Moderate and heavy pollution weather are 6 days in total, mainly in winter and spring seasons. Analysed the meteorological condition on air pollution days with the combination of valley terrain conditions in Lanzhou City, the major meteorological reasons for the formation of air pollution in winter are temperature inversion and calm, air pollution in spring is also affected by the sand storm weather.Secondly, the concentration of common pollutants SO2 and NO2 in this area in heating period went down year by year from 2005 to 2014. It shows that after Lanzhou City Hall launched revised edition of "Lanzhou City air pollution prevention and control law implementation measures" in 2006, city air pollution remediation of SO2 and NO2 has achieved good results. Although the concentration of common pollutants TSP and PM10 show decreasing trend over all, some monitoring points’results of 2012 and 2014 rebounded, And every monitoring point in this region exceeded the standard seriously during the ten years, this phenomenon should be paid attention to. The concentration of typical pollutant NMHC, H2S and NH3 showed a rebound after decrease, and the regional monitoring results of 2014 exceeded the standard. The comparison of the monitoring results in heating and non heating season of 2014 also show that the control effect of regional common pollutants SO2 and NO2 looks good, but typical pollutants concentration exists obviously excessive. This phenomenon shows that the government and enterprises focused on common pollutants SO2 and NO2 in the previous stage of air pollution control process, but ignored the contribution of petrochemical enterprise typical pollutants to the air pollution in the region, and volatile organic compounds like volatile organic compounds are an important source of PM2.5 in Xigu District.Thirdly, the study area within the numerous unorganized emission sources was equivalented to three sources as the refinery, the fertilizer factory and the rubber factory, worked out unorganized emission source of Lanzhou Petrochemical Industries Co by using the ground concentration reverse calculation method, according to the concentration monitoring results of typical pollutant NMHC, NH3, H2S in this region in 2014. Then worked out that the fertilizer factory’s contribution of NMHC for this region is 177.0kg/h, its contribution of H2S for this region is 2.365 kg/h, and its contribution of NH3 for this region is 22.301kg/h, the rubber factory’s contribution of NMHC for this region is 52.2 kg/h, its contribution of H2S for this region is 2.122 kg/h, and its contribution of NH3 for this region is 14.56kg/h, the refinery’s contribution of NMHC for this region is258.5 kg/h, its contribution of H2S for this region is 4.76 kg/h, and its contribution of NH3 for this region is 37.18kg/h.Fourthly, predicted the concentration contribution of Xigu petrochemical concentration district unorganized source for the concerned points, and set up the limited value of typical pollutants as 100%,70% and 50% of the secondary standard of national air quality, according to immediate, mid-term and long-term air quality control programs, and worked backward the unorganized source reduction.Lastly, proposes corresponding reduction measures for major plants of Xigu petrochemical concentration district which discharge typical pollutants, according to immediate, mid-term and long-term control programs. Immediate control measures of installing flow meters, spill-proof probes and gas recovery facilities for oil-loading stage of Xigu petrochemical concentration district will reduce the emission of NMHC by 874t/a. These measures can reduce the refinery’s unorganized emission of NMHC obviously, make a crucial importance to the regional immediate unorganized control. |
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