Influence of pulverized coal properties on heat release region in turbulent jet pulverized coal flames

The effects of pulverized coal properties, volatile matter, particle size and moisture content, on the heat release region in turbulent jet pulverized coal flames were investigated experimentally. To understand the accuracy of line of sight measurement in the two-dimensional (2-D) visualization, point measurements of chemiluminescence intensity by cassegrain optics were also conducted. The heat release region for the structure of pulverized coal flame was observed through visualization by CH∗ chemiluminescence image with an intensified high-speed camera, and by CH∗ chemiluminescence intensity for local point measurements. The streamwise length of the heat release region based on 2-D visualizations was about 11.4% longer than that of point measurements and increased proportionally to the volatile matter content. The temperature rise for 35-45 μm coal particles was faster than that for 75-90 μm particles, which resulted in a shift of reaction region toward upstream direction. The length of heat release region depends upon the particle size and the volatile matter. However, the coal moisture content less than 15% shows minor effect on the heat release region comparison to volatile matter and coal size within our experimental conditions.