In order to understand the emission characteristics of volatile organic compounds(VOCs)in the flue gas of coal-fired units with different capacities and the control effect of air pollutant control equipment(APCDs)in different tails on VOCs,online and offline sampling tests were carried out at the 400 MW subcritical offset combustion unit and 1 000 MW ultra-supercritical tangential combustion unit of Yund-ing Meizhou Bay Electric Power Company in Fujian Province.Theses tests aimed to obtain the whole-process concentrations of methane,non-methane total hydrocarbons and other VOCs in flue gas.The results show that the total non-methane hydrocarbon concentration be-fore SCR of 1 000 MW unit(24.66 mg/m3)is lower than that of 400 MW unit(33.36 mg/m3).This disparity can be attributed to the higher load and furnace temperature of the 1 000 MW unit,along with the prolonged residence time of coal in the tangential combustion furnace,re-sulting in more thorough coal combustion.The SCR system of the two units can remove more than 70％of the total non-methane hydrocar-bon,with removal rates of 88.43％for 400 MW unit and 74.32％for 1 000 MW unit,respectively.In the electrostatic dust removal(ESP)process,the high voltage electrostatic field may cause the fly ash to release some VOCs,thus increasing the VOCs concentration in the flue gas.Following the implementation of all APCDs,the VOCs emission concentration of 400 MW unit and 1 000 MW unit is 8.40 mg/m3 and 8.47 mg/m3,respectively,with the overall removal rate of 73.98％and 63.02％.Notably,almost no methane is detected.The offline test results show that the main components of VOCs after coal combustion in Indonesia are n-hexane,benzene series and benzaldehyde.The or-ganic content analysis of various solid samples(such as coal,ash,gypsum)shows no obvious correlation between VOCs type and unit size.These findings have important significance for further understanding the impact of coal-fired power plants on air quality and optimizing the design of pollution control equipment.In actual operation of coal-fired power plants,pollution control equipment should be optimized accord-ing to specific conditions to achieve the maximum removal effect.It is also necessary to consider the unit size and operating efficiency to ef-fectively control VOCs emissions.
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