(639b) 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.