The Mechanism Study On The Photocatalytic Removal Effect Of Coal Fly Ash On Hg And NO In The Coal-fired Derived Flue Gas

The Photocatalytic detoxification technology of Hg and NO is a newenvironmentally friendly processing technology and thus has attractedextensive attention during these years. The Photocatalytic detoxification ofthermal power plant flue gas Pollutants is in its infancy stage in our country.The experimental research on the effect of coal fly ash on Photocatalyticactivity is expanded based on the need of mercury removal for coal-fired powerplant in this pape. The study on removal mechanism characteristics of Hg andNO of coal fly ash after the Hg removal research of coal fly ash onPhotocatalytic activity. First, a experimental device of fly ash photocatalyticremoval from flue gas pollutants is designed and developed Combined with theneed for this topic, which can not only meet the research needs in this study,but also provide a reference for Photocatalytic detoxification of Hg incoal-fired power plants.The fly ash sample between APH and ESP was selected and then wasscreened by physical methods and magnetic separation to get some of thephysical and chemical properties of fly ash, such as the particle size distribution,the magnetic composition, unburned carbon content, surface structure, hemicalcomposition and the UV light absorption characteristics.And then, the mechanism study on the photocatalytic removal effect ofcoal fly ash on Hg and NO is experimentally studied on the Multiphase Flowsystem developed by our research group. The results showed that Photocatalytic activity of fly ash was affected by different modificationmethods on it, including impregnated fly ash through the iron salt solution, P25load of fly ash and other physical and chemical methods. It was found that themercury removal efficiencies by the fly ash left under UV light dropped as thetemperature rises. The UV light can promote the physical and chemicalabsorption ability of fly ash to mercury and ultraviolet irradiation and NO cansignificantly increase the oxidation ability of fly ash for flue gas mercury. Butthe NO removal efficiencies by the fly ash under UV light is very low. Mercuryreduced photocatalytic denitrification activity of fly ash.Iron oxide compositions of the fly ash is an important factor to affect thefly ash photocatalytic activity. The flue gas mercury adsorption by thenon-magnetic fly ash is weaker than the magnetic fly ash, but higherphotocatalytic activity under ultraviolet irradiation in this study. Compared withabsence of light, the UV light improves the removal rate of Hg. Ferric chloridecompositions of the fly ash improves the photocatalytic activity removal rate ofHg, but the ferric nitrate modified fly ash almost lost photocatalytic removal offlue gas mercury. When the coal fly ash coated with TiO₂, the removal rate ofHg and NO is improved,and the removal rate of NO shows5.4%and9.2%presence and absence of Hg vapor, but Hg removal rate shows86.7%. Mercuryreduces the photocatalytic activity of the denitrification of fly ash coated withTiO₂.