Particle Characteristics in the Radiant Section of a Coal-fired Utility Boiler

Abstract

Particle data on a 160 MWe corner-fired, pulverized-coal fired boiler operated by New York State Electric and Gas (NYSEG) were collected as part of a comprehensive series of measurements taken to better understand the complex phenomena involved in pulverized-coal combustion, and to develop information suitable for model validation of comprehensive combustion codes. Changes in operating conditions involved variations in coal type, the amount of overfire air, load, and burner tilt. The measurements discussed include those of particle size, velocity, concentration, and an analysis of the concentration probability density function. The particle data were collected using the laser-based PCSV (Particle Counter Sizer Velocimeter) probe. PDF calculations were based on particle velocity distributions measured with the PCSV probe and particle data rate statistics measured with a frequency-to-voltage converter connected to the signal processing system. Measurements for this test series were collected primarily in the radiant section of the boiler and showed that both particle size and velocity were sensitive to the boiler operating conditions. Particle sizes generally decreased with increasing vertical distance, and measured velocities were influenced by the location of air inlets at most locations in the boiler. In contrast to the measured particle sizes and velocities, cumulative number densities and the associated PDF's showed little sensitivity to the variables investigated during this test. Concentration levels were fairly constant in the radiant section of the boiler, and then dropped significantly above the nose. Analysis of the probability density functions showed that the log-normal distribution function best fit the experimental concentration probability density functions at all locations in the boiler.