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Show Combustion Combustion tests were performed in B&W's basic combustion test unit (BCTU), shown in Figure 4. It is a water-cooled, horizontal furnace with an optimal firing rate of about 5-million Btu/hr when firing pulverized coal. The combustion chamber is cylindrical with a diameter of 4-1/2 feet, and is 8 feet long. It is partially lined with refractory brick to bring flame temperatures more in line with larger units. Two separately fired air heaters are capable of supplying 800°F combustion air. A number of viewports mounted on the furnace permit visual observations and provide access for various probes for detailed in-flame measurements. Coal-water fuel was supplied to the furnace with a system consisting of a 500-gallon storage tank equipped with a stirrer, a variable-speed progressing-cavity pump, and a mass flowmeter. An electric heater was also available for heated CWS tests. A dual-fluid, internal-mix atomizer was used to inject the CWS into the furnace in the form of a fine spray. Compressed air was used as the atomizing fluid. The burner used was a research burner having four concentric air zones that provided flexibility in how the air entered the furnace. Two of the zones were equipped with devices for imparting swirl to the flow, and another was equipped with a natural gas burner for firing the furnace at full load on natural gas. The burner was also equipped with a bluff-body stabilizer for improved ignition stability. -10- |