Electrostatic Distribution in the Riser of the Multizone Circulating Fluidized Bed for Polypropylene

This work investigates the electrostatic distribution in the riser of a multizone circulation fluidized bed for polypropylene by various electrostatic measurements. Results show all measured electrostatic parameters have a strong dependence on flow patterns with increasing bed height. They remain constant in dense-phase pneumatic transportation, while they decrease in fast fluidization. However, their polarities are different. The charge-to-mass ratio is negative under all conditions, but the negative electrostatic potential only appears in the lower part of the riser at lower gas velocities. Further signal source analysis shows that only contact electrostatic potential generated by charge transfer has a one-to-one correspondence with real charge on particles. In addition, compared to the induced potential, the contact potential in regions with higher solids concentration tends to be more negative under stronger effects of charge transfer, while in regions with lower solids concentration it tends to be mo...