| Lanzhou Xigu petrochemical industry district is the largest petrochemical base in northwest China.It is an important support for the economic growth of Lanzhou city,which is located in Lanzhou Xigu District,but its environmental pollution problem is becoming more and more serious.How to wage VOCs pollution prevention and control efficiently,improving the regional environmental air quality has become an important issue to local government and enterprises.This paper is aimed at provide reference for the management of VOCs in the enterprise and also provide the scientific basis for the local government to formulate the air pollution control plan of Lanzhou Xigu petrochemical industry district and carry out environmental management and planning.Based on the investigation of the source of VOCs in Xigu petrochemical industry district and the calculation of its source intensity,this paper analyzes the contribution of varied pollution sources to VOCs concentration at regional sensitive points,and selects the key pollutants of VOCs in Lanzhou Xigu petrochemical industry district.Meanwhile this paper proposes a reduction solution and analyzes the environmental benefits of the solution.The main conclusions are as follows:(1)On the basis of collecting relevant information of VOCs emission sources in Lanzhou Xigu petrochemical industry district,We divided the source area into 39 parts,and Calculate source strength in each part.The results show that the maximum pollution source is 159 oil loading and unloading bridge,and the discharge is 2344.85t/a.The second is 160/161 oil loading and unloading bridge,the discharge is 1007.14t/a.(2)Predict the concentration of pollutants at the sensitive point which provide by pollution sources under the typical daily weather conditions through the Aermod model,we can see: 106 loading bridge located in fertilizer plant has the largest percentage concentration contribution to Lanzhou first water plant,159 loading bridge in oil storage plant have the largest percentage concentration contribution to other sensitive points.The top five pollution sources contribute to the concentration of each sensitive point are the key pollution sources which have great influence on the regional ambient air quality.(3)Based on the investigation of the relevant information of VOCs pollution sources and the selection of key pollution sources,Discuss the reduction of VOCs sources in the region and forecast the environmental benefits.(1)Add vapor recovery equipment to 160/161 loading bridge set up the reference scenario.The forecast results show that the maximum concentration per hour of VOCs in the Zhongchuan highway section is less than the relevant requirements in " Detailed Emission Standard for Air Pollutants " under the standard scenario,the rest of the sensitive points VOCs maximum concentration per hour are exceeded.So we need a further reduction to pollution sources.(2)When the proportion of all pollutants in the area is reduced by 30% according to the policy requirements,the maximum concentration per hour of pollutants in Lanzhou No.1 Waterworks exceeds the limit of total hydrocarbon content of non-methane in the;“Detailed Emission Standard for Air Pollutants”.Increase the rate to 35% the maximum concentration of pollutants at the sensitive points are less than the standard.Compared with the baseline scenario,the reduction of the key pollution sources and the reduction of all the pollution sources,it is concluded that the environmental benefits for the reduction of the key pollution sources are large,and the improvement of the environmental quality of all the pollution sources is not obvious.(3)Choose a condition that the maximum concentration of pollutants in the reference scene is almost the same to the environmental quality standard.According to the contribution rate of the concentration of each pollution source to the sensitive point,the B value method is used to reduce all pollution sources.The 106 bridge has the largest reduction rate,the second is 3 # tank surface source in refinery.Consider the results of the selection of key pollution sources and the reduction potential of each pollution source to optimize the B value method,Transfer the rest of the pollution reduction to 159,106 bridge which is easy to governance and have great potential and have the maximum contribution at the sensitive points by concentration contribution proportion,the reduction rate is 20.64% and 74.34%.The predicted results show that the optimized B value method has better environmental benefits.(4)Considering the contribution rate of pollution sources at the sensitive points and economic and technical feasibility of governance,select 106 loading bridge and the 159 loading bridge which have great potential and have the maximum contribution at the sensitive points to propose a specific reduction plan for priority reduction.The reduction rate is greater than the optimized B value method,so the environmental quality of the sensitive points can be up to the environmental quality standard,and the prediction results show that the environmental quality improvement is obvious at each sensitive point. |
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