| SO2 and NOx are one of the most important pollutants in the air,and a series of environmental problems such as photochemical smog and acid rain are formed.In order to control the emission of SO2 and NOx?NO accounted for up to 95%of the proportion of NOx?,a large amount of research on flue gas desulfurization and denitrification was carried out.On the basis of previous studies on the desulfurization and denitrification of highly efficient absorbent NaClO2,it is considered that the addition of alkaline additives into NaClO2 solution is helpful to the absorption of NOx,but the low concentration of NaOH can inhibit the absorption of NOx.Therefore,this paper explores the addition of a cost-effective weakly alkaline additive urea in NaClO2 solution,while promoting the absorption of SO2 and NO.The experiments were performed to study the removal of SO2 and NO from the flue by NaClO2/urea solutions composite absorbent in the spray tower designed by ourselves,on the basis of high removal efficiency of SO2,the experiments mainly explored the effect of NaClO2 concentration,urea concentration,SO2 inlet concentration,NO inlet concentration,initial pH value and temperature on the removal efficiency of NO,the optimal process conditions were selected,the mechanism of removal of SO2 and NO from the flue gas of NaClO2/urea composite absorbent was analyzed.The results indicated that the average desulfurization and denitrification rate were 100%and 95.2%respectively when the absorption liquid NaClO2 concentration was 4 mmol·L-1,urea concentration was 0.5 mol·L-1,the initial pH was 7,the temperature was 50 °C;SO2 was absorbed liquid absorption process was divided into two parts:a part of SO2 dissolved in water was oxidized to SO42-by NaClO2,another part of the SO2 dissolved in water and reacted with urea and oxygen to generate?NH4?2SO4.NO which is insoluble in water was oxidized into NO3-and a small amount of NO2-by NaClO2 and then absorbed by urea,NO was reduced to environmentally friendly gas N2.Based on the principle of thermodynamics,the possibility of reaction,the limit of reaction and the effect of temperature on the reaction were analyzed,and the feasibility of the removal of SO2 and NO in flue gas by NaClO2/urea composite absorbent was verified.The grade of SO2 and NO,the expression of the rate equation and the apparent activation energy were studied by using the method of macroscopic reaction kinetics. |
PDF Full Text Request