Effects of Particle Size Distribution and Oxygen Concentration on the Propagation Behavior of Pulverized Coal Flames in O2/CO2 Atmospheres

Abstract

The ignition and flame propagation behavior of pulverized coal particles in an O2/CO2 atmosphere was studied in a long quartz tube reactor. The effects of mixing ratio of fine (mean diameter 16 μm) and coarse (mean diameter 82 μm) coal particles and oxygen concentration on the ignition characteristics, flame front distance, and flame propagation velocity were investigated by capturing the flame ignition and propagation using a high-speed video camera. The experimental results show that the particle size distribution has a strong influence on the ignition and flame structure of coal particles. Smaller coal particles result in earlier ignition, a smoother flame front, longer flame, and faster flame propagation velocity. Mixing of smaller coal particles with larger ones shortens the ignition delay and enhances the propagation velocity of the flame front. For different coal particle size distributions, the variation of flame propagation velocity with time in general displays an “M”-shaped curve. The curve of ...