Effects of Biomass Particle Size on Flame Structure and Combustion Characteristics using Blended Coal/Biomass Fuel in a Pulverized Coal Swirl Burner

The flame structure and combustion characteristics of co-firing coal and LPG with different sizes of biomass were investigated in a dual swirl pulverized coal burner by using a high-speed camera with bandpass filter and PIV system. Three sizes of spent mushroom compost (<45, 45~90, 90~150 μm) were cofired with pulverized coal (45~90 μm) at a blending ratio of 20%. When the biomass of the same size with coal was used, the turbulence intensity had the highest uniformity while other cases exhibited locally strong turbulent intensity. The combustion using <45 μm biomass was terminated early compared to other conditions, whereas the reaction region was the widest for 45~90 μm biomass. The flame had uniform turbulent intensity with wide and strong reaction when the biomass size was equal to that of coal. When using 45~90 μm of biomass, high velocity was maintained in the overall region and CH * radical was observed in a wide region with the highest radical intensity.