| With the rapid growth of social economy,the petrochemical industries have been developing significantly.Instead of coal using,petroleum products have become one of the most important energy sources.In the processes of production and uses of petroleum products,a large number of Volatile Organic Compounds(VOCs)are produced,which will increase the concentrations of PM and ozone in the atmosphere and cause frequent air pollution,such as haze.Therefore,the current research focuses on the VOCs emissions from typical petroleum refining plants in a petrochemical industry and the analyses of VOCs emission characteristics in different production processes of oil refining plants.The field investigation and literature review method was used to obtain the production process,raw materials and exhaust emissions of refinery enterprises.On this basis,exhaust gas from 11 monitoring points,namely,vacuum heating furnace,atmospheric heating furnace,sulfur recovery,delayed coking,continuous reforming,oil tank waste gas and factory boundary air was selected for monitoring.Two methods of air bags and online collection were used to collect samples from 4 to June 2017 and September 2017 to February 2018,respectively.Samples were analyzed by GC-MS instruments.The concentrations variations,distribution patterns,environmental effects and sources of VOCs were analyzed based on the analysis results.(1)The VOCs species in different process of oil refining plants have some similarity.The concentrations of alkanes at four points of pressure reduction heating furnace,sulfur recovery,delayed coking and oil storage tank were all over 50.00%,and alkanes was the most abundant species at the four points.The contributions of alkanes and aromatic hydrocarbons at each point were higher(>70.00%)to the total,and VOCs was the most important pollutant in refinery palnts.(2)There are some differences in the main compostions of VOCs in different process emission sources.The exhausts gas of two points in the vacuum heating furnace and the atmospheric heating furnace were mainly from the fuel burning flue gas,and the distribution patterns of the VOCs components at the two point positions were similar.(3)The change of VOCs daily values in the boundary of industry displayed bimodal distributions in autumn and winter.The concentrations in the morning and evening was higher than that of the rest.The concentration of VOCs showed 5 periods of deep pollution in Sepetember to December,and VOCs concentration showed a downward trend in 10-12 months,and showed an upward trend after December.The average volume fraction of TVOCs in autumn and winter was 80.95×10-9、90.96×10-9 respectively,and the concentrations of VOCs in winter was higher than that in autumn influenced by weather conditions.(4)The ozone formation potential(OFP)and the formation potential of two organic aerosols(SOA)in the boundary of industry was estimated by the maximum increment response coefficient(MIR)and the two organic aerosol generation coefficient method(FAC)method respectively.The results showed that the OFP contribution of olefin and aromatics was the largest,and their contribution rates were 47.17%and 63.95%,respectively;the SOA contribution of aromatic hydrocarbons was the largest,and the contributions in autumn and winter were 94.35%and 89.36%,respectively.(5)The PMF analysis model was used to analyze the source of VOCs.The results showed that there were 6 sources,namely,biomass source,solvent source,fuel volatile source,automobile tail gas source,combustion source and industrial source.The 6 emission sources may be affected by the East gas station of the monitoring point,the contribution of the fuel volatiles is the greatest,followed by the automobile tail gas source,the contribution rate is 41.16%and 17.46%,respectively. |
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