| Along with the continuous deepening of waste gas treatment in the chemical industry,the waste gas pollution of enterprise sewage station has gradually become the focus of fugitive emission control.Standard for fugitive emission of volatile organic compounds,which was issued in May 2019,requires enterprises to control the unorganized waste gas from wastewater collection,transportation,storage and treatment facilities.Fugitive emission from a sewage station of an organic chemical enterprise in Jiangsu Province was serious,which had a negative impact on the atmospheric environment quality of the surrounding areas.Therefore,based on the field investigation,detection and analysis of the waste gas composition and emission laws,and on the basis of the calculation of the waste gas source strength,the waste gas collection mode of each treatment unit is optimized by Solidworks Flow Simulation.Through the research and comparison of the waste gas purification process,the combined process of“alkali absorption packed tower+regenerative combustion furnace（RTO）”is adopted to treat the waste gas,and the by-product biogas is used as the auxiliary fuel,effectively reducing the operation cost.The main research contents and conclusions are as follows:The main pollutants in the waste gas from the sewage station of the company are VOCs and H2S.For closed UASB reactor and open water treatment structures,the actual measurement method and WATER9model calculation method are used to calculate the waste gas source intensity under the design condition.By actual measurement method,the average VOCs emission rate of UASB reactor is 5.56kg/h and the average H2S emission rate is 0.44kg/h.By WATER9 model calculation method,the average VOCs emission rate of open water treatment structure is 16.2kg/h under design condition.By studying the mechanism of gas collecting hood,the structure of gas collecting hood is optimized by Solidworks Flow Simulation,and the 3D model of gas collecting hood is established and the calculation grid is divided by using the fluid analysis software.The distribution of air velocity and relative pressure in gas collecting hood is simulated and analyzed.According to the experience data and relevant manual,the air volume of the waste gas collected by the company’s sewage station is 19820m3/h.Based on the study of waste gas purification process,the combined process of"alkali absorption packed tower+RTO"is selected.In order to ensure the efficiency of waste gas purification,the combustion chamber of RTO device is simulated and analyzed by engineering analysis software.The results show that the residence time of waste gas in the combustion chamber is more than 1.5s,the maximum stress of the shell is185Mpa,and the maximum deformation is 1.324mm.All parameters meet the design requirements.Study the biogas desulfurization process and adopt the Fe2O3 dry desulfurization process to pretreat the biogas.The by-product biogas after pretreatment is used as auxiliary fuel in RTO.The heat balance calculation results of RTO device show that if biogas is used as auxiliary fuel,the maximum consumption is60.2Nm3/h,and the biogas output of sewage station of the company is 63Nm3/h under the actual working condition,which can meet the fuel consumption demand of RTO device.After the waste gas collection and treatment device is built and put into operation,the VOCs purification efficiency is 99.3%and the heat recovery efficiency of RTO is 95.2%when wastewater flow is close to 90%of the design value and the combustion chamber temperature is 820℃;the emission concentrations of VOCs and H2S meet the standard requirements;the VOCs emission of the water treatment structures except the UASB reator is 11.4kg/h by actual measurement method,which is 29.6%lower than the estimated value of WATER9 model calculation method.The total investment of waste gas collection and treatment system equipment in the sewage station of the company is 5.56 million yuan,and the annual operation cost is predicted to be 978 thousand yuan. |
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