Experimental Study on the NOx Removal by Scrubbing with Urea-H2O2 Solution after NO Partial Preoxidation

The NOx removal by scrubbing with urea-H2O2 solution after NO partial preoxidation was investigated in detail by experiments in a spray empty absorption tower. Various operating parameters including the liquid-gas ratio, residence time, degree of NO oxidation, H2O2 concentration, organo-additive concentration, absorbent solution temperature, and PH value were tested to investigate their influences. Results indicate that the NOx removal efficiency increases with increasing of the temperature and PH value of the absorbent solution. The addition of H2O2 can effectively enhance the absorption of NO, and the denitrification efficiency increases obviously when the organo-additive is used. It is relatively cost effective to control NO oxidation degree at 50% because NOx can be effectively absorbed via the reaction process: NO + NO2 + H2O -> 2HNO(2). The NOx removal efficiency increases linearly with increasing of the residence time and is little affected by the liquid-gas ratio. Under the optimal test conditions, more than 75% denitrification efficiency has been achieved. The proposed denitrification method is relatively low-cost and promising.