Electrostatic Charging of Particles in a Straight Pipe

Title: Electrostatic charging of particles in a straight pipe

Poom Bunchatheeravate¹, Yusuke Fuji², Jennifer Curtis¹, and Shuji Matsusaka²

¹Department of Chemical Engineering, University of Florida, Gainesville, FL 32611. USA

²Department of Chemical Engineering, Kyoto University, Kyoto 615-8510. Japan

As two surfaces come into contact, electrons are transferred between the two surfaces. This phenomenon leads to one surface gaining additional electrons and become negatively charged, while the other surface becomes positively charged. Contact electrification is a common occurrence in dilute pneumatic conveying. When particles are transferred via pipelines, particles collide with each other and the bounding surfaces causing charge to build up on the particles. Excessive charge build up can lead to several issues ranging from particle agglomeration to deadly dust explosions. Under the correct piping conditions, it is possible to control the particle charge as the particles travel through the conveying line. This study propose an experimental technique for measuring the particle charging properties on a small experimental scale, as well as a model which can predict the particle charging behavior when conveyed through a straight pipe of any given length and diameter. The experiments involved measuring the particle charge at the inlet and the outlet of a 1m pipe. The charge of the inlet particles was modified using a particle charger. The particle charge exiting the 1m pipe is directly related to the particle charge when entering the 1m pipe. Knowing this relationship, a particle charging profile can be generated which shows the evolution of particle charge as particles travel through a pipe with the same material and diameter. The particle charging profile yields the equilibrium charge and the characteristic length. Both of these parameters depend upon the electrical interaction between the particle material and the pipe wall material.