OCR Text |
Show respectively, at the burner; the excess oxygen level was maintained at 3 percent. Stable combustion with a distinct swirling, dark-brown, lazy flame pattern was obtained. Flue gas temperatures were generally about 50° to 140°F higher than those measured during a baseline oil test due to formation of deposits in the boiler furnace and fire tubes. The carbon-conversion efficiencies were above 99.7 percent and about the same as when burning No. 6 fuel oil. The boiler efficiency tended to decrease with time from 82.7 to 80.4 percent because of the increase in the flue gas temperature. The boiler efficiency for oil firing was about 82.4 percent. Molten SRC Tests The major modification to the fuel train for the molten SRC tests was the addition of a melt unit. The melt unit consisted of a melt tank, a pressurized separator tank, a reciprocal pump to deliver the melted SRC from the melt tank to the separator tank, and a Dowtherm heat transfer system to provide a heat source for the melt tank and to maintain the temperature of the melted SRC in the fuel train. The main burner nozzle used in the SRC melt tests was the Industrial Combustion nozzle used for SRC slurry firing, but the atomizing medium was changed to superheated steam. Two molten SRC combustion tests were performed at full boiler load. A total of 2800-pounds of SRC was burned in 11 hours. The flame was a bright bushy type without a distinct swirling pattern. Fuel flow fluctuations due to problems in the control system caused the excess oxygen level in the flue gas to vary from 2.4 to 4 percent throughout the test. Flue gas temperatures increased slightly during the tests; however, there was no indication of serious deposition problems. The carbon-conversion efficiency and the boiler efficiency ranged, respectively, from 99.2 to 99.7 percent and from 81.9 to 82.5 percent. They were about the same as those of the oil and SRC slurry tests. 14-12 |