Gas/solid flow characteristics for a down-fired utility boiler with different arch-supplied OFA injecting angle

The arch-supplied OFA technology and matched efficient combustion measures were proposed for a FW type down-fired boiler. A gas/particle two phase cold airflow experimental system were established by modeling the utility boiler mentioned above with a proportion of 1:15. Three-dimensional particle dynamic analyzer (PDA) was used to measure the parameters such as the velocity of gas-solid phase, fluctuating velocity, particle volume rate and particle mean diameter in the model furnace. Gas/solid flow characteristics with different OFA injecting angle were investigated. With the increase of the OFA injecting angle, the injection depth of the fuel-rich airflow decrease, and the residence time of solid particle in the lower furnace shorten. The OFA penetration depth first increase and then decrease with the OFA injecting angle increasing. When the injecting angle is 20°, the gas-solid phase velocity and fluctuating velocity on the horizontal and vertical direction for the OFA airflow delay slowly, moreover, the OFA airflow and the recirculation zone below the arches did not affect each other. Therefore, the injecting angle 20° is more appropriate for the arch-supplied OFA program.