Simultaneous measurement of mass flow rate and charge-to-mass ratio of particles in gas–solids pipe flow

This paper summarizes our research on the theory and application of particle charging in gas–solids pipe flow. The particles moving in a pipe are charged by collisions with the pipe wall. The charge transferred from the particles to the wall per unit time is equal to the electric current flowing from the wall to earth, and the current depends on the mass flow rate and the charge-to-mass ratio. Conversely, these values can be calculated from the electric current using a special technique; i.e., two short pipes that are made of different materials are installed in series with electrical isolation. The principle of the calculation is based on the contact charging between different materials and the charge balance in the system; the simultaneous equations can be solved analytically. This method is applicable to online measurement for polymer powders as well as mineral powders.