Current distribution and particle motion in a barbed plate electrostatic precipitator

Abstract

Electrohydrodynamic theory suggests that a modification in electrode geometry is a method of creating more favorable electrical and flow conditions in electrostatic precipitators. A novel barbed plate precipitator is designed to provide a more uniform current density distribution and electric field in the inter-electrode gap. Ground plate current densities of both a conventional wire-plate precipitator and the optimized barbed plate precipitator are compared. Particle motion is observed via a laser light-sheet and measured with a laser Doppler anemometer. Streamwise and transverse mean and fluctuating particle velocities, particle motion length scales and diffusivities are measured at electrical and flow conditions typical of industrial precipitators. Ground plate particle collection patterns are photographed. Results show a hexagonal arrangement of barbs provides a more uniform current density distribution and electric field than exist in the wire-plate geometry. Additionally, the barbed plate creates a stronger electric field throughout most of the inter-electrode space and therefore generates higher particle drift velocities. However, the barbed plate increases the magnitude of the electrically generated turbulence. Length scales are of the same order in the two geometries even though the electrode spacing of the barbed plate is double that of the wire-plate precipitator. From an electrical standpoint, the barbed plate design is superior to the wire-plate precipitator. The more uniform distribution of current and electric field coupled with higher levels of mixing suggest the barbed plate may be most suitable for use as a precharger in the entrance section of a parallel plate precipitator.