| Summary: | 碩士 === 弘光科技大學 === 環境工程研究所 === 96 === This study applies O2/recycled flue gas (O2/RFG) combustion technology for waste incineration to investigate the emission characteristics and control efficiency of acid gases (CO2,CO,NO,HCl,SO2), heavy metals (Cr,Cu,Pb,Zn,Cd) and organic pollutants (PAHs,phenols,benzenes) at different feed gas compositions and ratios of recycled flue gas. The air pollution control devices including cyclone﹐a bag houseequipments﹐and a wet scrubber were set up to investigate the control efficiencies of CO2 and the other pollutants.Experimental results indicate that the concentrations of CO2,CO,NO,HCl and SO2 in the exhaust gas was increase a with the raising O2 concentration in feed gas. The recycling of exhaust gas can also enhance the concentration of CO2, the highest value is 72.9% if Oxygen concentration was 40% and the ratio of recycled flue gas was 70%, which is five times of the CO2 concentration in general air combustion system. The concentrations of acid gas SO2 and HCl also increase with the exhaust gas recycling, but that is not obvious for NO.Additionally, experimental results show that using this O2/RFG combustion incorporated with NaOH wet scrubber has great control efficiency of CO2, and even 100% removal is achieved. The improve of acid gas SO2 and HCl control in such system is not obvious due to the NaOH scrubber in general air combustion system originally having very good control efficiency for them. The control efficiencies of CO and NO in some conditions are not good and have no obvious relationship with the O2 concentration in feed gas and ratio of recycling flue gas. The increase of NO removal is only occurred at 60% and 80% O2 concentration in the feed gas.The control efficiencies of PAHs in such NaOH scrubber are not obvious but the control efficiencies of phenols and gas-phase benzenes are good at high O2 concentration and flue gas recycling. The pastitioning of heavy metals in such O2/RFG combustion system are also studied. The partitions of heavy metals in sand bed or fly ash collector are increased with the increased ratio of recycled flue gas. The control efficiencies of heavy metals are therefore increased.
The results of cost analyses for O2/RFG combustion system show that the CO2 control cost is reduced as the O2 concentration and RFG ratio were increased. with 40% O2 concentration and 70% RFG ratio.the CO2 control cost down 30%.Totally speaking, O2/RFG combustion technology can reducing the amounts of exhaust gas, change the concentrations and emissions of various pollutants, and further improve the control efficiencies of CO2 and the other pollutants in a combustion system. It is worthy to be further developed and popularized.
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