OCR Text |
Show EXPERIMENTAL SETUP Furnace IGT furnace No. 1 was used for these experiments. The overall furnace system is shown in Figure 2. The furnace has a square cross-sectional area of 13.5 ft with a length of 14 feet. Combustion air preheat temperatures of up to 1200°F can be achieved with a separately fired air preheater. The furnace is equipped with up to 58 cooling tubes, each of which has a 2.4-inch OD. Each tube can be independently inserted through the roof to any desired depth in the furnace to simulate a furnace load. The heat absorbed by each tube is calculated by measuring the water flow rate to each tube and the temperature difference between the water inlet and water outlet temperatures. The furnace is constructed of 23 cm (9 in.) hard refractory walls with exterior steel clading. One side has 31 independently removable panels or sampling doors to insert probes to any radial or axial position in the combustion chamber. For this project, the furnace had modified internal dimensions of 90 cm (3 ft)) high, 140 cm (4-1/2 ft) wide, and 240 cm (8 ft) long. The flue was placed on the center of the rear wall with a square opening of 30 cm by 30 cm (1 ft). Three water cooling tubes were placed vertically on each sidewall of the furnace to simulate a load in a boiler furnace (Figure 3). The tubes were extended down 60 cm (2 ft) from the furnace roof so that approximately 30% of the heat input was absorbed by the cooling tubes. The furnace wall temperatures for some tests were measured with four thermocouples: one each at the roof, flue, front, and rear sidewall. Burner The burner used for all the combustion trials was a movable-vane boiler burner (Figure 4). The burner has air swirl vanes that can be rotated to change the degree of combustion air swirl. For all tests, the vane angle was set to 60 degrees. The burner was mounted on a block that had a 110-degree total exit cone. Different fuel nozzles can be inserted down the axis of the burner to vary the fuel velocity rates, injection angle, and location of the nozzle tip on the burner axis. Three types of fuel injectors were used in these tests: a 1-inch axial nozzle, a 1- 1/4 inch axial nozzle, and a gun-type nozzle with six 45-degree radial ports on the round tip. The size of these ports was changed during the testing. The end of the gun-type 16-8 |