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Show A ThermoElectron Model 14-A analyzer was used for measuring nitrogen oxides, a Beckman Model 864 analyzer for carbon monoxide, a Beckman Model 755 analyzer for oxygen, and a ThermoElectron Model 40 analyzer for sulfur dioxide. The air and fuel inlet temperatures were measured with Type K thermocouples. Thermocouples were also installed at two locations in the combustor to measure the wall temperatures at the following points: Front Wall - Located midway between the axial air inlet and the sidewall next to the axial air inlet. Flue - Located 1 foot into the flue. The outlets of these thermocouples were connected to a multipoint chart recorder for constant monitoring. The gas temperatures within the combustor were measured by a suction pyrometer. The output of the platinum/platinum-13% rhodium thermocouple was recorded on a calibrated chart recorder. TESTS WITH AVERAGE HEATING VALUE OFF-GASES At the design firing rate of 3 X 10° Btu/h the flame with the average heating value gas was unstable until the fuel and combustion air were preheated to 335° and 750°F, respectively. At these conditions the combustor wall temperatures were also stable. Therefore, a fuel temperature of 350°F, air temperature of 750°F, and the design firing rate of 3 X 10° Btu/h were selected as the nominal firing conditions for the combustor performance tests. Following these tests, the ratio of the axial to radial air was varied to determine the best operating ratio. No appreciable affect on the flame was noticed when the ratio of the two radial air flows was varied. However, when the axial air flow was reduced, a reduction in swirl was visible, and when axial air flow was increased, the flame started to move out of the front half of the combustor. It was decided to keep the axial air at 30% of the total air and the two radial air flows equal. Effect of Excess Air on Performance Figure 6 shows the effect of excess air on CO, S02, and N0X emissions corrected to 0% oxygen in the flue gases. The CO concentration decreased rapidly with an increase in excess air levels up to 15% excess air and then 5.7.10. I N S T I T U T E OF G A S T E C H N O L O GY |