MODELING AND MEASUREMENT OF PARTICULATE MATTER (PM) COLLECTION FROM BOILER EXHAUST GAS IN ELECTROSTATIC WATER SPRAYING SCRUBBER

Abstract

Boiler exhaust gas consists of many components that cause air pollution, such as: particulate matter (PM), SOx, NOx, COx, etc. These pollutants normally are mixed. To eliminate them, an electrostatic water spraying scrubber is used, depending on a coal fuel used for combustion source in the furnace. For PM, new guidelines will be changed from the existing 10 to 2.5 microns within the next few years. The scrubber is widely used for the collection of PM from industrial exhausts because of its low equipment and maintenance costs combined with operational safety and high collection efficiency. This study presents computed and experimented results of PM collection efficiency in an electrostatic water spraying scrubber. In this scrubber electric attraction between charged PM and charged water droplet improves PM collection considerably over conventional scrubber. Computed model takes into account initial liquid momentum, hydrodynamic and electric forces. The effects of operating parameters, such as gas velocity, applied voltage, charge to-mass ratio on PM collection efficiency within the scrubber, were also investigated. Computed results are in good agreement with the experimental data obtained in the laboratory. Compared to inertial scrubbers, the electrostatic water spraying scrubbers can operate at lower flow rate, but total collection efficiency is over 98% of all PM sizes.