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Show SECTION 4.0 RESULTS AND DISCUSSION 4.1 CWM ATOMIZATION CHARACTERISTICS The CWM's atomization characteristics were determined in the cold flow facility. This characterization was performed with the same atomizer used for the combustion tests. The primary variable during the atomization tests was the ratio of atomizing air flow to the CWM flow rate. The CWM flow rate was held constant at a rate corresponding to a heat input of 2,500,000 Btu/hr. The measurements reported in this paper were made at an axial distance 10 inches from the atomizer. The testing showed that the mean drop size changed very little at axial distances greater than 4 inches from the atomizer. The mass median diameters (MMD) and Sauter mean diameters (SMD) produced by the CWM's tested are shown in Figure 5 as a function of the amount of atomizing air. For comparison, the performance of water in the atomizer is also included. The atomizer produced an MMD of 25 microns with water at an atomizing air to CWM mass ratio of 0.1 (Figure 5a). The utility grind CWM's (Elk Creek, Chinese "0" and "X" coal) all resulted in similar mean drop sizes of 45 microns at M . /M of 0.15. The micronized CWM made from Elk Creek air7 CWM coal produced a somewhat finer mean drop size of 35 microns. The bimodal CWM, not shown, produced a substantially larger drop size distribution. As a further point of reference, the mass median diameter of the utility grind Elk Creek coal was also measured using the Malvern instrument and found to be 29 microns. The effect of CWM formulation and atomizing air to CWM flow rate on drop size distribution is shown in Figure 6. The experimental system not only determines a characteristic drop size but also produces size distributions. This figure shows drop size distributions for water, the utility grind Elk Creek coal and the micronized CWM. The figure illustrates that the decrease in mean particle size as the amount of atomizing air is increased as a result of a decrease in the largest drops. In Figure 6 the particle size ranges are from 6 to 565 microns. 18 KVB72-P327 D194 |