STATIC ELECTRIFICATION PHENOMENA IN PNEUMATIC TRANSPORTATION OF COAL

Electrostatic charge is generated by contact, friction, separation, etc. between particles, and between particles and pipe walls. The powder flow pattern in a pipe greatly influences the charge generation. The flow pattern in small piping systems is considered to be different from the one in practical pneumatic systems where 50 - 300 mm diam. transport pipes are usually used. Bearing this in mind, the authors used relatively large pipes in order to study electrostatic phenomena. An attempt was made to investigate the relationship between charge generation characteristics and transport conditions for coal, using a large, straight piepline system (53 mm diam.). It was found that static electrification phenomena are affected by the powder concentration and the transport velocity and that the electrostatic charge increases, peaks and decreases with increasing concentrations or velocities.