Effect of Feeder Inner Structure on Feeding Performance for Absorber Sphere Pneumatic Conveying

The sphere feeder is an important component of the absorber sphere shutdown system for absorber sphere conveying. Absorber sphere is entrained and fluidized in the feeder by conveying gas to form gas-solid flow. The effect of feeder inner structure, i.e. the draft tube height, on the feeding performance was investigated. Experiments were conducted in the positive pressure conveying system with ambient air as the source gas. The glass sphere was used to replace the absorber sphere. Three types of feeder inner draft tube relative position were considered. Five combinations of the draft tube height were tested with feeder inlet air velocity in the range of 15∼30 m/s. Experimental results showed that feeder inner draft tube height played an important role on the feeding performance. Different characteristics for the starting process of the sphere conveying were observed. The difference of sphere blown away pressure and steady conveying pressure could be reduced to about 5 kPa, which was negligible from the view point of conveying blower selection in engineering application. Sphere stagnation region was observed near the bottom of the feeder. The obvious boundary of stagnated sphere and fluidized sphere was formed for the steady conveying. Two types of control model were observed for sphere steady feeding rate. One was that the sphere steady feeding rate was determined by sphere flow through the orifice. The other was that the sphere steady feeding rate was determined by gas-sphere fluidization and entrainment. These results were important for optimization sphere feeder design.