Electric charging characteristic of a mixer-type powder disperser

The charging characteristic of a mixer-type powder disperser has been studi ed experimentally. A dry powder was dispersed and electrically charged simu ltaneously inside the disperser. The charging performance was evaluated in terms of the mean value of specific charge measured by a Faraday cage. The effect of the disperser's configuration and operating conditions on the gen erated electrical charge were investigated. The measured particle charge wa s found to decrease with operating time and reached a constant value after 15 min. One of the reasons for this time-dependent characteristic is the fo rmation of a powder layer on the wall surface. As for the charging mechanis m, it can be concluded that particles contacting with the inside wall of th e disperser are responsible for most of the observed charge. The charging e ffect, however, deteriorated at the double-wall section of the disperser wh en the effective height was over 100 mm.