Emission characteristics of PAHs, benzene and phenol group hydrocarbons in O_2/RFG waste incineration processes

摘要

This study applies the oxygen/recycled flue gas (O_2/RFG) combustion technology for waste incineration in a laboratory-scale fluid-ized bed incinerator to investigate the effects of different RFG percentages and O_2 concentrations on the emission characteristics of organic pollutants (PAHs, phenol and benzene hydrocarbons). Experimental results show that most PAHs with high-ring structures were present in solid-phase and most low-ring PAHs were present in gas-phase. The major compounds of benzene and phenol hydrocarbons were benzene, toluene, trichlorobenzene and 2,4-dinitrophenol, phenol, dichlorophenol, respectively. As the O_2 concentration in feed gas was increased from 21% to 40%, the emissions of solid- and gas-phase PAHs and phenol compounds were decreased but not for benzene compounds. Increasing RFG percentages would decrease the emissions of gas-phase PAHs, benzene and phenol compounds, but increased those of solid-phase pollutants. The best operating conditions of such O_2/RFG combustion system to reduce the emissions of PAHs and phenol compounds were 40% O_2, 35% RFG, and that for benzene compounds was 21% O_2, 75% RFG. Comparing with conventional air combustion system, the best diminution efficiencies of PAHs, benzene and phenol compounds at such O_2/RFG conditions were 59.54%, 70.97% and 52.60%, respectively. With proper feed gas compositions and RFG percentages, the combustion efficiency and destruction efficiency of organic pollutants can be improved by this O_2/RFG combustion technology.