Emission Charactoristics Of Particulates And Polycyclic Aromatic Hydrocarbons From Coking Processes

China has the largest coke production and export in the world,and more than 40% global coke output and more than 60% gobal coke export are from China.Coke production shares about 13% of the total coal consumption in China ,which is higher than the global average level.Besides CO2 and SO2, Many organic pollutants ( such as polycyclic aromatic hydrocarbons, PAHs) also emit from coking processes,causing greatly adverse effects on local environment and human health.Four coke ovens with different height were selected in present study, including the height of 6m,4.3m and 3.2m, and flue gases, the air on the top of coke oven and in the coke plants were sampled.The souce profile, emission factors and emission amount were discussed,which will play an important roly in the scientific assessment for the influence of coking industry on national and regional environment. Major conclusions are listed as following:There are great differences among the concentrations of particulates from coke processes with different height of coke ovens,in which 6m emits the lowest, while 3.2m emit the highest. Of all the point-sources during coking processes, the concentration of particulates in combustion stack gas is the highest,followed by those in charging and pushing emissions.The concentrations of PAHs in air on the top of coke ovens are lower than thoes in flue gas,and BbF (0.87μg/m3) is found to be the most abundant of the 16 PAHs studied. Among the different coking stacks studied, pushing emission has the highest concentrations of total-PAHs followed by charging emission,and combustion stack emission has the lowest ones.Obvious differences of PAHs distributions exist in different coking processes. For charging and pushing emission, 4-ring PAHs account for the largest percentage which are 49.47% and 45.99%, respectively. However, 3-ring dominate in combustion flue gas,which account for 44.89% of the total PAHs. and 5-ring PAHs are the the most abundant of PAHs in air on the top of coke oven.The source profile of coking and the ratio of BaP/BghiP,BaP/COR,PYR/BaP,IND/BghiP,Phen/Ant and BeP/BaP are different from other pollutant source which can be used for tracing the source of PAHs to some extent.Toxic characteristics of PAHs differ in various sampling sits. Pushing emission has the highest level which is consistent with the concentration. Although the concentrations of PAHs in air on top of coke oven is the lowest, their toxicity level is higher.Emission factors of particulates and PAHs are average 0.518 kg/t coke and 63.076mg/t coke in coking flue gas,respectively. Pyr, FluA and PhA has the largest emission factors in flue gases of charging and pushing, which are 3.926, 2.052 and 1.397 mg/t coke, respectively. Pyr, AnT and PhA has the largest emission factors in combustion stack, which are 8.360, 7.654 and 6.698mg/t coke.Based on the national coke production from byproduct coke oven battery in 2008, the discharge amount of particulates and PAHs are 163170t和19.869t, respectively.