Study On Removal Mechanism Of SO₂, NO_x And HG Of Coal-Fired Flue Gas By Photocatalytic Oxidation Combined With Liquid Absorption

This paper is to study removal mechanism of SO2, NOx and Hg of coal-fired flue gas by photocatalytic oxidation combined with liquid absorption. The performance of nano-titanium dioxide photocatalytic oxidation to remove coal-fired flue gas pollutants was evaluated by the photocatalytic oxidation combination of liquid absorption evaluation system. The removal performance of SO2, NOx and Hg was studied under different conditions, and then come to the best process route for removal of SO2, NOx and Hg.This thesis is divided into three parts:(1) Preparation and characterization of nano-titanium dioxide using sol-gel prepared for TiO2gel calcination at different temperatures for different crystal structures. By dip coating of titanium dioxide on the metal matrix titanium mesh or glass fiber cloth. TG-DSC thermal re-analysis of the crystal form of titanium dioxide prepared at different temperatures.(2) Removal performance of SO2, NOx, and Hg was evaluated by photocatalytic oxidation combined with liquid absorption system. Design and build the photocatalytic oxidation combination of liquid absorption evaluation system. The influence of concentrations of pollutants, light intensity, liquid absorption to the removal performance of flue gas SO2, NOx, and Hg by photocatalytic oxidation combined with the liquid absorption was studied. Design and build a carbon-based adsorption fixed bed evaluation system to compare with photocatalytic systems for mercury removal performance under the conditions of the same inlet concentration.(3) Numerical simulation to study NOx and mercury form transformation properties under different atmosphere conditions using chemical reaction kinetics.Through experiments, the following conclusions:(1) it was found that in photocatalytic oxidation combined with liquid absorption experiment, when SO2concentration were400ppm,800ppm,1400ppm,the removal efficiency of SO2were98.78%,98.10%,89.90%, with the increase of the concentration of SO2, the removal efficiency of SO2decrease.(2) It was found that in photocatalytic oxidation combined with liquid absorption denitration process, UV light catalytic NOX removal role. With the increase in the concentration of NOx, the removal efficiency of NOx decrease. With the reduction in light radiation intensity, the removal efficiency of NOX decreases. Using different concentrations of KMnO4-H2SO4solution, it was found that NOX removal efficiency increased with the KMnO4concentration.(3) It was found that higher homemade TiO2calcination temperature in a muffle furnace, the removal efficiency photocatalytic oxidation of mercury was higher. Speculated that particle size of TiO2nanoparticles was smaller at500℃,with more catalytic activity. When the Adsorbent carrier for the aluminum silicate fiber and metal titanium mesh, the mercury removal efficiency were76%,100%, it was found that metal titanium mesh had better mercury adsorption properties.As the reaction temperature, the ability to dip bromide activated carbon adsorption of mercury was enhanced.(4) It was found that in photocatalytic oxidation without liquid absorption experiments, with SO2concentration nditions from400ppm to800ppm, the removal efficiency of Hg decreased speculating SO2due to light catalyst section inactivation. With the increase of the concentration of NOx, the removal efficiency of SO2decreased. Indicating that NO had a competitive adsorption with mercury. It was found that, in photocatalytic oxidation combined with liquid absorption experiment, while the concentration of SO2/NOx/Hg were400ppm,200ppm,12.5u g/m3, the removal efficiency of SO2/NOx/Hg were97.78%,40.12%,60.02%. It can be proved that the photocatalytic oxidation combined with the liquid absorpti to removal SO2/NOx/Hg feasible.