Experimental study of particle residence time distribution in coke-burning riser of combustor used for petroleum coke

Key words:  coke-burning riser  combustor  phosphor particle tracer  residence time distribution  diffusion model

Abstract:

The particle diffusion behaviors in the coke-burning riser of a novel internal mixing type of combustor used for petroleum coke were studied through measuring the residence time distributions (RTD) of particles by impulse phosphor tracer technique. The diffusion characteristics were analyzed. The experimental results show that the RTD curves of solids in 1.0 meter detecting distance of the riser are unimodal and the peak height decreases gradually from the axis to the wall. Moreover, the RTD curves of solids in 4-0 and 9.4 meter detecting distance of the riser are composed of a sharp-high leading peak and a long tail, and their peak heights are nearly same. The solids diffusion mechanism in the riser can be explained by the diffusion of dispersed particle and cluster. A lateral diffusion model and an axial superposition model were established to predict the particle diffusion behaviors in 1.0 meter and 4. 0 meter detecting distance of the riser, respectively. The predicted results obtained by the model are in good agreement with the experimental data.