| OCR Text |
Show Particle size, velocity, and temperature are measured simultaneously with a fast-response optical system which monitors radiant emissions from the 9 particle. Individual pargicles passing behind the image of a two-slit coded aperture produce a double-pulse signal from which size, velocity, and temperature are determined. Size is determined by ratioing the pulse heights, and velocity is calculated from the transit time over a fixed distance. Temperature is determined by measuring the transmitted light at two different wavelengths (bandpass filters centered at 500 and 800 nm) and applying two-color pyrometry. Measurements are made on one particle at a time, and they are repeated 200 to 400 times to generate number distributions of size, temperature, and velocity. Optical constraints limit the particle size to 4 3 a minimum of 50 ym and a maximum number density of 10 /cm . Particle heating rates have been measured and are similar to those in pf boilers. Overall particle burning rates per unit external surface area are determined from the size, temperature, and velocity measurements by means of mass, heat, and momentum balance. The Fuels The chemical analyses of the as-received Kentucky No. 9 and AFB elutriate samples are given in Table 1. The coal was supplied by TVA with an overall size range of 0.63 cm (0.25 inches) x 0. This was further classified by sieving into various size fractions at ORNL. The AFB elutriate was obtained from the TVA 20 MW(e) pilot plant during no-recycle operation with Kentucky No. 9 coal as the feed. The entrained-flow experiments and the TG experiments were conducted with the 75-150 ym sieve cut of Kentucky No. 9. The elutriate samples fed to the entrained-flow reactor were also primarily in the 75-150 ym size range, but the elutriate samples for TG were sized to be 98% < 45 ym. 8 |
