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Show COMBUSTION MEASUREMENTS IN AN INDUSTRIAL GAS FIRED ALUMDWM RECYCUNG FURNACE 2 Figure 1. Schematic illustration of the natural gas-fired aluminum melting furnace illustrating the complex reacting flow field including the four burners and exhaust port. is approximately 49.5 in (1.26 m) high from the melt line (fully charged) to the roof, 12 ft (3.66 m) wide, and 17.5 ft (5.33 m ) from front to back. T w o Air Products, Inc. EZ-Fire™ oxygen enrichment burners are located on either side of the exhaust flue, and are numbered here sequentially 1 through 4 with burner 1 being nearest the access door for dross removal. The outer burners (1 and 4) are vectored toward the furnace symmetry line at a 7° angle, while the inner burners (2 and 3) are fired parallel to the symmetry line. All four burners are vectored downward (toward the aluminum melt) at a 10° angle. Of proprietary dual design, the burners can operate in both oxygen/fuel and air/fuel firing modes independently. During high-fire operation, both oxygen/fuel and air/fuel burners operate simultaneously in an overall oxygen-enriched combustion mode. When furnace temperatures exceed desired levels or while tapping of the molten aluminum occurs, the furnace is operated in low-fire mode, utilizing only the air/fuel burner. A large door, which can be opened for dross removal, forms the front wall of the furnace parallel to the furnace symmetry line. A furnace wall insert was constructed by plant personnel to provide access to the combustion space of the furnace during operation. The insert was constructed of mild steel with five 4 in (10 c m) diameter pipes welded to the wall through which water-cooled probes could be inserted for furnace probing. As shown in Fig. 1, the insert was centered in the front wall of the furnace, and the five access holes were spaced at 19.5 in (0.5 m ) intervals. The flame-exposed face of the insert was wrapped in high-temperature insulation to prevent heat loss from the furnace while the insert was in place. The furnace door was lifted, the insert was placed on the furnace sill, and the door was lowered onto the insert until a relatively tight seal was achieved. The clearance gap between the wall insert and the furnace, as well as unused access holes were plugged with high temperature blanket insulation. Figure 2 shows the position of the wall insert and probe locations relative to the furnace geometry and burner vectoring. The figure is drawn to scale to illustrate the probing locations relative to the anticipated flame. Effluent species concentration and gas temperature measurements were made in the stack of the furnace as well. These measurements were made by inserting the water-cooled probes through access holes in the refractory flue where available. Fuel (natural gas) flow rates were measured for the oxy- |
