Electrostatic Charging Characteristics of Polyethylene Powder During Pneumatic Conveying

A full-scale experimental rig has been set up to study the electrostatic charging characteristics and possible ignition hazards during pneumatic conveying and storage of powders. The rig consists of two large silos ( 55 m3 and 60 m3) which are connected via approximately 35 m length of steel pipe work. The powder conveying parameters such as velocity, relative humidity, dilution, etc., can be accurately controlled. The rig has been used to study the charging characteristics of polyethylene powder. Bipolar charging has been detected on the powder¿the fine particles charge negatively while the coarse particles charge positively. Electric field strengths up to 150 kV/m have been measured during the silo filling operation. Detailed measurements have been carried out on the charging characteristics of polyethylene as a function of different conveying parameters. The experiments and results are reported.