INFLUENCE OF PARTICLE-SIZE, FLUIDIZATION VELOCITY AND RELATIVE-HUMIDITY ON FLUIDIZED-BED ELECTROSTATICS

The influence of particle size, d(p), fluidization velocity, U-r, and relative humidity, RH, on the degree of electrification reached by a f luidized bed of glass beads has been studied. The static electrificati on of the bed was measured by means of the potential difference observ ed between an electric probe and the metallic distributor. The effect of relative humidity appears to be complex and is connected with the q uality of fluidization - bubbling or slugging - existing in the bed. A characteristic curve for electrification vs. humidity has been propos ed that consists of five zones. The results show that when the value o f the relative humidity is lower than a critical value (RH(c)), the st atic electrification of the bed cannot be measured accurately because the adhesion of particles to the probe leads to irreproducible voltage values. Also, the degree of electrification increases with particle s ize and air velocity. The relationship between the average solid circu lation velocity and electrification is studied.