EXPERIMENTAL-STUDY AND MODELING OF THE BURNOUT ZONE IN THE NATURAL-GAS REBURNING PROCESS

The reburning process with natural gas is an effective technique which can be applied in existing coal combustors in order to reduce the NOx emissions. The importance of the burnout zone in this process is grea t, because significant amounts of CO, unburned fuel and reactive nitro gen can reach this zone. The influence of the temperature and the air excess introduced in the burnout zone on the concentration of the nitr ogenous species has been studied. Experimental results have been deter mined of the concentrations of NO, HCN and NH3 in the exit gas for tem peratures ranging between 900 and 1100 degrees C and air excesses betw een 5 and 15%. An empirical correlation which fits the output NO conce ntration has been obtained. A simplified model has been developed to p redict the output concentrations of the most interesting nitrogenous s pecies.