Experimental Study On NO_x Reduction By Gas Reburning In O₂/CO₂Atmosphere

China is one of the countries that consume more coal than any others. There is agrowing concern about how to reduce the emission of CO2. Developing Oxy-FuelCombustion can provide great help for CCS. So it is very important to develop thetechnology of the reduction of pollutants in conditon of Oxy-Fuel Combustion.NOxis the incentive for many environmental problems. Oxy-Fuel Combustion andReburning Technology the typical techniques of Low NOxCombustion. Both of themcan reduce the emission of NOxup to70%. If they are uesd in the same time,In this paper, an experiment is carried out in the condition of Oxy-FuelCombustion and Reburning Technology in order to research characteristics of NOxreduction by reburning process. The influences of facters including temperature, excessair ratio and reburn fuel fraction have been studied.Experimental system is designed and built according to the study concent. Mixturegas is preheated by appropriate structures of the reactor, steam obtained by combustionproducts calculation is added to mixture gas.The temperature is from900℃to1100℃,the excess air ratio is from0.7to1.2, the reburn fuel fraction is from10%to30%.Andcontrast experiment with ash is carried out in order to be close to the real reactionsituation.Experimental results show that NO reduction efficiency increases with the increaseof the temperature of the reaction area. The NO reduction efficiency is about30%,when the temperature is1100℃, and there is a maximum value if the temperaturecontinuing to increase according to the trend of NO reduction ratio. When the excess airratio changes, NO reduction efficiency is affected by the atmosphere of recation area. Itincreases with the decrease of the oxygen value. The NO reduction ratio decreases from30%to10%as the increase of the oxygen value. The trend of NO reduction efficiencyexhibits a little difference when the reburn fuel fraction changing, but it still increaseswith the increase of the reburn fuel fraction on the whole. Comeparing the resulets withlow temperature ash, NO reduction ratio has a8%increase, but the resulests withnational standard ash has almost no difference. The analysis of the experimental resultswith ash and ash samples which are recovered after experiments show that Na in the ashdecreases significantly. Na in the ash is carried by gas flow in the form of compoundsand catalyzes the reduction of NO by reburning process.