Electrostatic Characteristics of Hydrated Lime Powder during Transport

Abstract

Electrostatic charging of fine hydrated lime with an average primary particle size of 2.5 μm under various transport conditions is studied. The charging tendency is evaluated in terms of charge-to-mass ratio, which is defined as the ratio of the accumulated charges to the powder weight. The charge-to-mass ratio of the hydrated lime is investigated at various gas velocities and powder mass flow rates. The effects of transport tube materials and surfactants are studied. In addition, the bipolar charging phenomenon that is commonly observed during silo filling is examined. The parameter of the powder mass flow rate is not generally considered in the theoretical formulation of charge transfer; however, this study shows that the powder mass flow rate has significant effects on the charge accumulation on powder. An empirical correlation of charge-to-mass ratio as a function of the gas velocity and powder mass flow rate is presented. The bipolar charging appears to occur during powder transport. Surfactant-modified hydrates exhibit charging behavior significantly different from that of toners with charge-control agents. While high solids loading favors low charge accumulation, it also increases the chances of discharging.

Homogeneous cooling state of dilute granular gases of charged particles

“…This feature is of great importance for industrial applications. [1][2][3][4][5][6] So far, however, the effect of electric charge on the dynamical behaviour of granular flows has hardly been addressed. When sufficiently fluidized, the interparticle interactions are dominated by binary, nearly instantaneous collisions, characterizing a flow regime referred to as a granular gas.…”

Charge Segregation Depends on Particle Size in Triboelectrically Charged Granular Materials

“…Also, the charging appears to depend on the nature of the particle size distribution (as discussed below), which is surprising because the particles are macroscopic (10-1000 m) and thus their sizes would seem to be irrelevant in regard to charge transfer. Nevertheless, this charging occurs in a wide range of contexts, including industrial applications such as fluidized beds [1] and pneumatic conveying [2], and natural phenomena such as sand storms [3], dust devils [4,5] and volcanic plumes [6]. One consequence of the charging is that it significantly alters the particle flows [7][8][9].…”

Modeling the electrostatic effect on the hydrodynamic behavior in FCC risers: From understanding to application

“…The generation of electrostatic charges because of continuous collision and friction between particle-particle and particle-wall, also referred to as triboelectrification, is an unavoidable and usually undesirable phenomenon in gas-solid handling devices, such as fluidized bed reactors (FBRs) (Ciborowski & Wlodarski, 1962;Park, 2000;Zhang, Yang, & Arastoopour, 1996), circulating FBRs (Hendrickson, 2006;Jiang, Bi, Liang, & Fan, 1994;Zhang et al, 1996), and pneumatic conveying systems (Lee & Fan, 1993;Liang, Zhang, & Fan, 1996;Watano, 2006;Wittmann, 1989). Recent progresses in understanding the mechanism of the electrostatic charge influence are rather limited.…”