Static electrification of powders during spray drying

In the field of pharmaceutics, spray drying is often used for producing particles with predetermined qualities. Produced particles are usually insulating in nature, and this property combined with small particle size, might lead to electrostatic problems. These problems involve, for example, dust explosions, fires, reduced process efficiency and particle accumulation on the walls. In the spray drying process, the static charge might be generated in different ways: double layer charging in the feed pipe, double layer or induction charging at the spray nozzle, and contact and frictional charging at the walls of the spray cylinder and the cyclone chamber. In this paper, these charging processes are assessed using electric field measurements and Faraday pail.