On-line, in-situ particle measurements in large scale applications

Abstract

A compact, optical probe was developed to provide on-line, in situ particle measurements in large scale, high temperature applications. Demonstration tests at the Watson Power Plant were arranged by Southern Company Services. The optical probe was used to obtain measurements of particle concentration, size, and velocity in the furnace (1330°C) and at the inlet and outlet of the electrostatic precipitator. A comparison of optical probe velocities with measurements made by pitot tubes showed consistent trends in velocity values as function of position in the duct. Cascade impactor and optical probe results were in good agreement for particle sizes up to 10 microns. The optical probe measures higher particle concentrations for particles larger than 10 microns. Differences in the large particle results are believed to be due to differences in large particle characteristics (refractive index, density) and to differences in the way particle information is measured and analyzed by the two techniques. Optical probe measurements showed that the greatest variation in the velocity and particle concentration occurred at the precipitator exit. These fluctuations indicate that processes such as rapping periodically release bursts of larger particulate. The most complex velocity flow field was also measured at the precipitator exit.