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Show opposite breastwall of Burner AS and are found in the region, where the flame envelope touches the glass surface. The weaker relative heat flux maximum associated with Flame A6 is located more . towards the center of the furnace due to the shortness of the high temperature zone of this flame. Impact of 02-Burner Elevation and Burner Angling It is clear from the previous statements, that burner positioning and angling must have some influence on maximum refractory temperatures, on net heat flux distribution to the glass and on overall heat transfer efficiency. In order to investigate these influences, 02 Cases 4 and S were conducted. In Case 4, both the AS and the A6 burners remained horizontally directed, but were lowered from 2 ft above glass surface to only 1.3 ft over glass surface. The impact of burner elevation on net heat flux distribution is shown in Fig. 12, which compares the results obtained for Case 4 with the heat fluxes predicted for the baseline 02 Case 3. By lowering the burners from 2 ft to 1. 3 ft, peak heat f luxes at the glass increased from 115 kW 1m2 to 122 kW 1m2. This increase is accompanied by a decrease of peak roof refractory temperatures by 15 R (8 K). A still more dramatic effect on heat flux distribution to the glass is obtained when the 02-burners are angled towards the glass surface in direction of the furnace center-line (Case 5). The relative mass flux distribution utilized in this case is shown in Fig. 13. Fig. 14 shows the gas temperature distributions predicted for the angled 02 flames. Compared to the hori zontal 02 flames of the baseline case (Fig. 10) ; maximum flame temperatures decreased by ca. 150 (F). This is an indication for an improved heat transfer to the glass surface. The net heat flux distribution at the glass surface produced by the angled flames is depicted in Fig. lSb. Compared to the baseline Case 3 (Fig. lSa)~ maximum heat flux densities increased from 115 kW/m2 to 131 kW/m and, as can be expected, the location of the heat flux maximum of each flame shifted more towards its corresponding burner wall. The increase of peak heat fluxes is accompanied by an overall increase of heat transfer efficiencies (see section on overall performance). The angling of the 02-burners also causes a considerable redistribution of refractory temperatures as shown in Fig. 16. Compared to the distribution for the baseline 02 Case 3 (Fig. 11), maximum roof refractory temperatures are lowered by 20 R (11 K) and the location of roof pea't fluxes has shifted towards Burner AS. However, the stronger flow along the glass after 14 |