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Show axisymmetric models, the flame remains aligned on the kiln centerline; off-axis effects such as burner tilt or buoyancy are not included. Based on these results, it was determined that the optimum location would be approximately 3 feet behind the dam. In the case where the burner was 6 feet behind the dam, the flame was too wide as it enters the d a m section, leading to the possibility of major damage to the kiln. In the case where the burner tip is located within the d am section, the majority of combustion takes place well beyond the dam, so there is likely to be inadequate heating of the lime product that builds up at the base of the dam. Furthermore, there is no benefit derived from the air flow expansion caused by the dam, which can contribute significantly to the flame shaping. Therefore, the selected location is just slightly behind the dam. Temperature with Burner at the Crest of Dam r L -"w Flame Shape with Burner at the Crest of Dam -w i 1 I Temperature with Burner Retracted 3 feet Flame Shape with Burner Retracted 3 feet Temperature with Burner Retracted 6 feet Flame Shape with Burner Retracted 6 feet Figure 8. Results of two-dimensional CFD analysis. The next stage of the modeling effort involved creating the three-dimensional grid (as shown in Figure 6) and finding the correct positions and orientations of the kiln burner and the waste gas gun. In these sets of models, the firing conditions corresponding to Combination "B" in Figure 3 were used for the two burners. The first case that was run had the kiln burner located on the centerline of the kiln and oriented parallel to the centerline. The waste gas lance was oriented parallel to the kiln burner and offset by 2 feet above it. The results of this configuration are shown in Figure 9 and illustrate what can happen if the burners are not correctly installed. The waste gas does not sufficiently penetrate into the kiln, and consequently a significant amount of combustion takes place at the top of the kiln immediately behind the dam. This would most certainly cause rapid refractory wear. When the final configuration was obtained, the results were as shown in Figure 10. The kiln burner is placed so that it is parallel to the ground (i.e., tilted 1.8° downward from the kiln centerline). The kiln burner is also mounted 6 inches off the kiln centerline in the direction of the lime bed. This allows more room for the S O G gun at the top of the , ., rr, * • u u .* «.u *u Figure 10. CO concentration (top) and kiln. The waste gas gun is 6 inches shorter than the , . .. _.. .. ' *' . & b temperature distribution (bottom) kiln burner and is offset from the kiln burner by 2 for final configuration Figure 9. CO concentration (top) and temperature distribution (bottom) for trial configuration. 7 |