Ignition And Combustion Characteristics Of Pulverized Coal Based On Potical Entrained Flow Reactor

It’s of great significance to study the ignition and combustion characteristics of pulverized coal,under different gas flow conditions and different pulverized coal conditions,for clarifing the mechanism of coal ignition and guiding the industrial practice of the burner design and power station operation. Because of the difference of the experimental system used by different researchers, the ignition and combustion mechanism of pulverized coal in different conditions are still not unanimous. The lack of advanced optical diagnostic technology has restricted the development of coal ignition and combustion research field.On the basis of literature research, in view of the existing problems of the present research in the field of pulverized coal ignition and combustion and the demand of the subject, in this paper, a optical entrained flow pulverized coal reactor system was designed and built, which provides reaction condition that is maximum close to the combustion environment of the pulverized coal boiler,and the system can obtain further research on ignition and combustion characteristics of pulverized coal by using a variety of optical diagnostic tools. And char can be collected to auxiliary analyse combustion mechanism. An pulverized coal flame spontaneous emission measurement system based on ICCD camera, SLR cameras and other equipment as well as an image processing method were introduced in this paper,by which it realizes quantitative calculation and analysis of pulverized coal jet flame ignition delay time and main combustion section length.Through two methods of the actual measurement and numerical simulation, it shows the rationality of the design of the test system, and it achieves the predefined performance index by the adjustment and improvement of the test system. By Simulating the combustion environment of two kinds of pulverized coal, it illustrates the rationality of the test scheme.Ignition and combustion characteristics of pulverized coal under high temperature conditions is researched on the optical entrained flow pulverized coal reactor system. The total ignition point and main combustion section length,ignition point and main combustion section length of volatile was respectively obtained from coal jet flame’s toal intensity(full wave band in blackbody radiation)distribution curve and the OH spontaneous radiation distribution curve. The most important parameters affecting the combustion of pulverized coal are investigated,including ambient temperature, ambient oxygen concentration, coalranks and particle size. And the method of judging the ignition mode of the pulverized coal is presented by comparing the total ignition delay time of the pulverized coal and the ignition delay time of volatile.The results show that:with the improvement of ambient oxygen concentration,the total ignition delay time of pulverized coal in different conditions is linear decrease and main combustion section length was shorter; the bituminous coal particles of medium grain size in 10% oxygen concentration ignited hetero–homogeneously and in 20% and 30% oxygen concentration ignited heterogeneously;the lignite particles of medium grain size in 10% and 20% oxygen concentration ignited hetero – homogeneously and in 30% oxygen concentration ignited heterogeneously; the bituminous coal particles of large grain size in 10% and 20%oxygen concentration ignited homogeneously and in 30% oxygen concentration ignited hetero – homogeneously. In the range of 1600K-1800 K, the influence of temperature change is small, and the increase of temperature can shorten the ignition delay time of pulverized coal slightly. The ignition and combustion characteristics of Zhundong coal and Shenhua coal are similar,but the ignition delay time of lignite is longer and the main combustion section length of lignite is shorter.In order to make the results of the study guide industrial practice, by arranging for primary wind air carrying pulverized coal and the outside secondary wind air coerced to achieve initial air atmosphere, and then an atmosphere of smoke, such that the optical entrained flow pulverized coal reactor system can simulate the combustion environment of the pulverized coal boiler in the maximum extent, and to do experiments on ignition and combustion characteristics of pulverized coal in approximate boiler internal combustion conditions.The results show that: in approximate boiler internal combustion conditions,the bituminous coal particles of medium grain size and the lignite particles of medium grain size ignited hetero–homogeneously,their Ignition and combustion characteristics are similar to which in10% and 20% oxygen concentration,the ignition and combustion characteristics of Zhundong coal and Shenhua coal are similar,but the ignition delay time of lignite is longer and the main combustion section length of lignite is shorter.In the range of1600K-1800 K, the influence of temperature change is small, and the increase of temperature can shorten the ignition delay time of pulverized coal slightly.