CFD-DEM simulation of particle vertical conveying in small absorber sphere system

Pneumatic conveying of small absorber spheres in pebble-bed High Temperature Gas-cooled Reactor is a special application of pneumatic conveying technique. The absorber spheres are discharged into the reflector boring when the discharge orifice is opened by the driving mechanism. Before the start-up of the reactor, the absorber spheres in the reflector boring need to be transported back to the sphere storage bin. The whole process consists of several sub-processes, e.g., the granular discharge from the sphere storage bin into the boring, granular discharge from the side reflector boring into the feeder, particle entrainment in the feeder, sphere conveying in the transport pipe, gas-solid separation and spheres pile in the storage bin. A brief summary of the recent experimental and discrete element method simulation work published by our institute are given, from the viewpoint of gas-solid flow and granular flow. CFD-DEM coupling simulation are recently used to investigate particle vertical conveying in the small absorber sphere system. Some typical simulation results of the sphere motion behaviors during the conveying process are introduced. The CFD-DEM model is useful to make a better understanding of the conveying process and to optimize the system design. (author)