Experimental Investigation on the Influence of Air Velocity on the Particle Dispersion Behavior of Rice Husk in a Fuel-Rich/Lean Burner

Recently the firing of biomass at existing power plant has drawn much attention because biomass fuels result in less pollutant emission. It is desirable to investigate the flow characteristics of biomass particles in existing combustors in order to determine whether the coal burners also have good adaptability for biomass fuel. The particle dispersion in the burner has a close relationship with pollutant emissions. In this paper, a monitoring system based on a charge-coupled device (abbreviated as CCD) camera was employed to measure the particle distribution of rice husk in a fuel-rich/lean burner. The influence of air velocity was taken into consideration. The particle-rich/lean ratio is 19.49, 16.23, 14.86, and 12.94 (corresponding to the air velocity of 9.5, 11, 12.5, and 14 m/s, respectively) at the exit of the burner model. The results indicates that the air velocity has a negative effect on the separation performance. In order to verify the particle distributions obtained by the digital imaging technique, specially designed filter bags were used to collect rice husk from both the fuel-rich side and fuel-lean side. Then mass and size distributions of the collected particles were analyzed. The results agrees with the trend above and indicates that the block-type concentrator has greater impacts on large particles. More large particles were collected from the fuel-rich side. The dispersion mechanism of rice husk particles revealed in this paper can propose solutions to the actual operation of plants that combust/co-combust the rice husk. (CSPE)