Measurements of solid concentration and particle velocity distributions near the wall of a cyclone

The particle velocity and concentration distribution in the near-wall region of the cyclone were experimentally studied. A series of measurements were conducted with fiber optical probes (FOPs). It was found the radial solid concentration distribution is severe non-uniform and particles agglomerate as dense spiral bands near the wall, moving downwards with a certain interval. On the cross-section plane, from the center to the wall, solid concentration increases. The average solid concentration near the wall increases with the gas velocity or solid concentration at the cyclone inlet. Along the moving particle bands, solid concentration increases and particle average velocity decreases. Under present experimental conditions, the thickness of the particle bands in the cylindrical section is about 4–12 mm. Particle velocity in the near-wall region is in the range of 0.5–2.5 m/s and its average value is insensitive to the operational parameters. The number of spiral bands increases with the cyclone's inlet gas velocity, and might be greatly influenced by the cyclone structure.