Changes in Electrostatic Charges of Fine Particles after Addition to Gas-Solid Fluidized Beds

Abstract

This chapter presents changes in electrostatic charges of fine particles after addition to gas–solid fluidized beds. Experiments are performed to determine the changes in the electrostatic charges of various free particles after addition to gas–solid fluidized beds to better understand their role in influencing electrostatic charge generation/dissipation. Electrostatic charge measurements are performed by an on-line Faraday cup employing the fluidization column as the inner Faraday cup, located symmetrically inside a second copper column forming the outer cup. Preliminary results show that the entrained fines leaving the top of the fluidization column carry charges, resulting in a net charge inside the bed. The charges carried by different frees (Larostat 519 antistatic agent, glass beads, and silver-coated glass bead particles) are determined for a range of operating conditions and relative humidities. Experiments are performed at various relative humidities (RH) of the fluidizing gas (0%, 15%, 35%, and 60%). The charge to mass ratio, Q/m, is determined for different added fines. Fines added to an initially charged fluidized bed carry significant but different amount of charges out of the column depending on their sizes and surface physical structure therefore, leaving a net charge behind. Experiments are performed to find the initial bed charges to determine the charging mechanisms because of the addition of fines.