Experimental Study On NO Emission Characteristics Of Blended Coal Combustion In A Variety Of Mixed Mode

Many of the current power plant boilers make coal burning blended to improve the utilization ratio of inferior coal, yet to ensure the stable and complete combustion of coal will lead to high emission of NOx. Experimental study on coal blending study at present mostly adopts a way that kinds of coal burn after mixed directly. But in the actual furnace condition, pulverized coal is emitted from the nozzles of different heights. Thus a new type of reactor was designed, which has quartz plates to make pulverized coal combusted in different layers. It makes the emission of NOx under different combustion conditions more authentic and reliable. Two kinds of typical coal(HSQ bituminous coal and lei LY anthracite coal) were selected as the object of research, and in the fixed bed reactor a series of research was carried to make a thorough inquiry on NO emission characteristics of coal combustion under different blending modes.The results of coal blended combustion show that: Improving the ratio of bituminous coal can advance the ignition and burnout, and improve the combustion performance of coal. When two kinds of coal burn blended, NO emission is between the concentration of these two kinds of single coal, and the NO conversion rate increases gradually with the growth of the proportion of anthracite; the interrelationship between these two kinds of coal has influence on NO emission, which is showed as form of inhibition or promotion when ratio of mixed coal is changed. NO emissions and NO conversion rate are lowest when the upper layer is bituminous coal and the lower layer is anthracite. The volatile of upper coal plays a important role in the reduction of NO in hierarchical hybrid combustion.The results of coal-char blended combustion show that: The volatile matter has a great effect on the suppression of NO emission under the condition of stratified combustion; The NO reduction degree of char as independent individual is greater than as a part of coal. The volatile of coal doesn't occupy the main position in the reduction of NO when bituminous coal and anthracite are blended in the upper, and the enhancement of reduction activity of pure char should be the main reason for the reduction of NO emission. NO conversion rate decreases with increasing stratification distance in the stratified coal-char blended combustion; when two kinds of coal are too far apart, the main factor of reduction of NO is not volatile bituminous of upper coal, but the enhancement of reduction activity of pure char.