Experimental Investigation On The Burnout And NO_x Emission Characteristics Of Coal Blends Combustion In O₂ /CO₂ Atmosphere

Considering Chinese energy structure and its utilization status, coal resources will remain the main energy in China in the near future. Mixed coal blending technology has been widely used since it can improve the adaptability of coal power plant coal-fired boiler to the coal. Oxygen-enriched combustion technology as one of the most potential CO2 capture technology can reduce NOX produced by the pulverized coal combustion.However, there has been no research papers related to mixed coal combustion in O2/CO2 atmosphere. On this background, this article will base on experiment results to focus on mixed coal combustion in O2/CO2 atmosphere and NOX emission characteristics. The sedimentation furnace experimental bench that can complete two kind of mixed coal blending combustion methods is the main experimental equipment, and the research object are four kinds of single coal and their two- mixed coal. The research carries out a comparative experiment on the coal blending combustion outside the furnace and inside the furnace respectively to observe blended coal combustion characteristic, and investigates the influence of mix proportion, oxygen coefficient, the mixing coal and combustion atmosphere on the NOX emission characteristics of mixing coal combustion.First of all, this paper analyzes the mixed coal combustion rate and the NOX emission characteristics of the mixed coal that combustion in the O2/CO2 atmosphere in a blending way outside the furnace. This experimental results show that the mixed coal combustion rate will increase with the growing mixed rate of flammable coal, but it will decline after the mixed rate reached at a point. This trend will be more obvious when the nature difference between the component coal goes up. The reason is inflammable coal plays two important roles during the mixed coal combustion. On one hand, the flammable coal is easy to burn, the combustion process improves the combustion environment temperature and then promotes uninflammable coal combustion. On the other hand,inflammable coal combustion will consumes oxygen in the atmosphere, that will put the uninflammable coal in oxygen-deficient combustion state, so the inflammable coal is hard to burnout. The emission of NOX during mixed coal combustion is near to the sum of the proportion emission of its different component.At last, this paper studies the burning characteristics of mixed coal that combustion in the O2/CO2 atmosphere in a blending way inside the furnace. The experiment results indicate that during the process of blending combustion inside the furnace, the inhibitingeffect inflammable coal had on uninflammable coal will reduce greatly, especially when the difference between the components of mixed coal increases. Besides, the NOX emissions of mixed coal under these conditions is lower than that of the blending combustion outside the furnace. Blending combustion inside the furnace can effectively improve the burnout characteristics of mixed coal, and reduce the emissions of oxynitride.The experimental results also show that the increase of peroxide coefficient during burning process can greatly promote the mixed coal burnout, but it will release more NOX.Compared with the air atmosphere, mixed coal burning in O2/CO2 atmosphere has a poor burnout characteristics, NOX emissions is much less.