Study On Wet Oxidation Denitrification By Sodium Chlorite And Its Industrial Application

In recent years,the environment and human health was serious threaten by the air pollution.The nitrogen oxide in the flue gas emissions to the environment makes the acid rain,haze,photochemical smog and other environmental problems becoming more and more serious,therefor,the flue gas denitrificationin is still the focus of air pollution control in the"'13th Five-Year plan' about ecological environmental planning".At present,the flue gas denitrification technology of large-scale boiler has been basically mature,the denitrification efficiency of SCR method can reach 90%or more,but in the problem of small and medium-sized boiler flue gas denitrification,SCR denitrification method needs high temperature makes it difficult to apply in small and medium sized boilers.It is urgent to find a kind of efficient and relatively economical technology which can be applied to denitration of flue gas in small and medium-sized boilers.Compared with dry denitrification technology such as SCR,wet oxidation denitrification technology is not limited by the temperature window with high removal efficiency,and has better feasibility and research prospects in the flue gas denitrification treatment of small and medium sized boilers.The difficulty of wet oxidation denitrification technology is how to make the low solubility of NO in the water could be removed quickly and efficiently.Therefore,to find efficient oxidants and optimize the process parameters for the operation of small and medium-sized boiler flue gas denitrification treatment has extremely important practical significance.In this paper,the oxidative denitration of the four oxidants in the bubbling reactor has been studied,including hydrogen peroxide oxidation,nitric acid absorption,sodium hypochlorite oxidation and sodium chlorite oxidation,with NO removal rate as the index.The denitrification effect of the four oxidants and the advantages and disadvantages of the process were compared and analyzed.The operating parameters of NaClO₂ wet oxidation denitrification technology were optimized by single factor experiment.The optimal operating conditions of temperature,pH,concentration of absorbed liquid,oxygen content of flue gas,initial NO concentration and flue gas flow rate were determined:T=40?,pH=4,CNaClO2=0.02mol/L,CO2=0%,CNO=1000ppm,V?=1L/min.The possible chemical reactions during the wet oxidation and denitrification were preliminarily deduced,and the thermodynamic analysis of the reaction process was carried out.The effects of temperature,pH and concentration of absorbent on the absorption efficiency were investigated by response surface methodology.The results showed that NaClO₂ was the main factor affecting the efficiency of wet oxidation denitrification.Based on the above research results,the denitrification technology was applied to small and medium-sized boiler flue gas denitrification and the flue gas successfully discharge standards.