(273f) Experimental and Numerical Investigations On the Electrostatics in the Downer Reactor

In fluidization processes and granular flow system, tribo-electrification is an inevitable phenomenon due to the continuous and random collisions between particulates and walls with different materials. In this study the electrostatic performance in the downer reactor of a triple-bed combined circulating fluidized bed was investigated through both experiments and numerical simulations. In numerical simulation Discrete Element Method (DEM) was adopted to simulate the electrostatic charge generation and transfer occurring in the downer. Both experimental and numerical results showed that the averaged induced currents caused by electrostatics increased with increasing solids mass flux in the downer, and the electrostatics was strongest near the entrance of the downer because of the highest frequency of collisions between particles and wall caused by the largest solids holdup at that location.  Numerical studies also revealed that the averaged induced currents increased with increasing initial particle velocity and particle size, and the averaged induced currents caused by the charge transfer was much larger than those by charge generation through tribo-charging. This is the first few studies in trying to reveal the tri-electrification in the fluidized bed, and may help us better understand the mechanism of electrostatic phenomena, and cope with challenges and problems caused by electrostatics.