Study On The Adsorption Mechanism Of Pollutants In Coal Combustion Process

In view of the deterioration of atmospheric environment, the aggravation of greenhouse effect, the destruction of ozone layer, PM2.5, acid rain corrosion etc, more and more attention have been paid on the emission and hazard of coal-fired power plant pollutants. Research in this paper mainly focuses on transforming current pollution control device of coal-fired boiler by injecting carbonaceous adsorbents into flue gas while adsorbing and oxidizing pollutants, therefore maximizing the utilization of current flue gas purification device while realizing combined removal of various pollutants of coal-fired power plant. Also, the characteristics and mechanism of pollutans from coal burning being adsorbed on carbonaceous adsorbents are deeply studied in this paper, providing technical support on realizing combined removal of various pollutants in coal-fired power plant.Quantum chemistry is introduced into the research on the adsorption and removal of pollutants on carbonaceous adsorbents. Carbon based surface model is firstly built by applying quantum chemistry calculation and the adsorption characteristics of nonmetallic pollutants in flue gas on carbon based surface model is studied by applying density functinal theory. Aiming at different adsorption sites on carbonaceous adsorbents surface, various adsorption processes and configurations, as well as the corresponding adsorption energy, bond length and bond population are optimized. By analyzing the adsorption characteristics of every pollutans on carbonaceous adsorbents, it shows that CO?CO₂?H₂S?NO?SO₂ and SO₃ are strongly adsorbed on carbonaceous adsorbents chemically and different pollutants compete for adsorption sites on carbonaceous adsorbents surface, with the adsorption strength of SO₂ being the strongest, followed by H₂ S, SO₃, CO₂, NO and CO successively.Due to the complexity of the adsorption process of trace elements Hg and Pb on carbonaceous adsorbents, which is mainly affected by other pollutants in flue gas, the mechanism of different gas compositions affecting carbonaceous adsorbents adsorbing trace elements is mainly studied. Results show that CO, CO₂, H₂ S, NO, SO₂ etc. in flue gas contribute greatly to the adsorption removal of Hg on carbonaceous adsorbents, transforming weak physisorption of Hg to strong chemisorption. According to the adsorption energy, NO promotes Hg adsorption the most, followed by H₂ S, SO₂, CO and CO₂ successively with SO₃ functioning counterproductively; CO, CO₂, H₂ S, NO, SO₂, SO₃ etc. in flue gas contribute greatly to the adsorption removal of Pb on carbonaceous adsorbents. According to the adsorption energy, CO promotes Pb adsorption the most, followed by H₂ S, SO₂, CO₂, NO and SO₃ successively, taking which into consideration, the injection sites of carbonaceous adsorbents are suggested to realize combined removal.