Study On Simultaneous Desulfurization And Denitration By Oxidation In A Rotating Packed Bed

China has a great number of coal-fired power plants with a huge coal consumption.And NOx and S02 from coal-fired flue gas cause serious environmental pollution in China.The multiple steps desulfurization and denitrification route was mostly adopted in industry,which has a large occupied area and high operating costs.Industrial boilers with a small or medium volumetric gas flow rate urgently require a cost-effective simultaneous removal technology.The wet desulfurization and denitrification technology has advantages of wide applications,simple process,and simultaneous removal of multi-component pollutants.Thus it is very suitable for the flue gas purification of the small and medium boilers.However,this technology is limited to low mass-transfer efficiency in equipment,and consequently the emissions targets of the treated gas cannot meet the increasingly stringent environmental requirements.As it is know to all,rotating packed bed(RPB)can greatly enhance the mixing and mass transfer.In view of these,this study employed RPB to enhance the absorption process of NOx and S02 with the pre-oxidation by ozone.The effects of various operating conditions on the efficiencies of desulfurization and denitrification,and the overall gas phase volumetric mass transfer coefficient(KGa)were investigated.Firstly,the denitrification experiments in the RPB were carried out to investigate the effects of various operating conditions including O3/NOx molar ratio(MR),rotation speed,gas-liquid ratio,absorbent concentration,initial NOx concentration on the removal performance of NOx,and the effect of NO2/NO mole ratio on removal performance of NO.The optimal operating conditions were obtained as follows:MR of 1,rotation speed of 800 rpm,gas-liquid ratio of 167,absorbent concentration of 5%.Under these operating conditions,NOx removal efficiency can reach 75.0%.Secondly,the simultaneous desulfurization and denitrification experiments in the RPB were carried out to investigate the effects of various operating conditions including MR,rotation speed,gas-liquid ratio,absorbent concentration,initial SO2 concentration,pH value of absorption liquid,oxygen percentage of simulated flue gas,gas flow,and absorbent additives on the removal performance of NOx and S02.Optimal operating conditions were obtained as follows:MR of 1.25,rotation speed of 800 rpm,gas-liquid ratio of 167,absorbent concentration of 7.5%.Under the optimal operating conditions,NOx removal efficiency and S02 removal efficiency can reach 73.1%and 97.3%,respectively.Finally,the lateral line tests were carried out to investigate the effects of various operating conditions including MR,gas-liquid ratio,rotation speed,and pH value of absorption liquid on the removal efficiency of NOx and SO2.Also,the industrial tests were carried out to investigate the effects of various operating conditions including MR,gas-liquid ratio,and pH value of absorption liquid on the removal efficiency of NOx and S02 at the factory site.The results showed that the desulfurization and denitrification efficiencies in RPB with the pre-oxidation by ozone was better than that of the original process.