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Show FUEUAIR MIXTURE PILOT 6 ~ I FLAME FUEUAIR MIXTURE MAIN BURNER FLUE GAS c=C> Figure 2. IGT/MAXON GAS-FIRED UL TRA-LOW-EMISSION TEST BURNER at the exit of each combustion chamber for further enhancement of the internal combustion product recirculation. A configuration of the flame stabilizer, including the length/diameter ratio of the chamber and the size and shape of the exit orifice, was determined from cold modeling results; the location and size of the main combustor exit orifice remain variable in order to permit changes in the main combustor configuration. Two tangential nozzles are employed for the flame stabilizer and four for the main combustor. Because the swirl flow and ICPR are driven by tangential injection from the nozzles, the injection velocity is an essential parameter for governing fluid dynamics in the cyclonic chamber. To enable optimized control of the nozzle velocity at different operating conditions, especially at turndown operation, all tangential nozzles are specially designed to allow a smooth adjustment of the cross-sectional area of the nozzle outlet while the combustor is operating. A flow diagram of the test system is shown in Figure 3. Combustion air and natural gas are premixed individually for each stage of the combustor. Flow rates of air and fuel are also metered and controlled individually. The flow rate of the premixed fuel/air mixture for each nozzle can also be adjusted for flow balance control. The test combustor is started up by a sequence start-up system that automatically controls system purge, ignition of a pilot by an electric spark, and fuel supply to each combustor. An interlock system is linked with the flame sensor monitoring the flame in the flame stabilizer for safety protection. Another flame sensor is installed on the main combustor. Signals from this sensor are acquired by the computer for monitoring flame stability and guiding combustion control in the main combustor. Data Collection The combustion rate and the ratio of air/fuel were measured individually for each stage. Exhaust-gas temperature and composition, inner wall temperature and pressure in the combustion chamber, and the static pressure at each nozzle were also measured for evaluation of the test combustor performance. The major data were collected by a computer data acquisition and reduction system, shown in Figure 3. 5 |