OCR Text |
Show ratio (0 - 3.0), initial NO concentration (100 - 500 ppm), and oxygen concentration (0.5-8.0%). The fIrst activity involved selecting an optimum atomization nozzle for the tests. Ideal nozzle characteristics included fme atomization and rapid mixing time. Open-air tests were conducted with fIve nozzles, including twin fluid nozzles made by Delavan, Spraying Systems and Sonicore, and pressure nozzles made by Bete and Hago. The Delavan and Hago nozzles provided the best spray patterns based on visual observations and were selected for furnace performance tests. Methanol was injected with each nozzle at 810 K. NO concentration was simultaneously measured at 750 and 500 K. The Hago nozzle had better performance and was selected for the test program. The spray pattern of the Delavan twin fluid nozzle was observed to be greatly longer than that of the Hago nozzle. It is believed that the Delavan nozzle propelled a significant fraction of the additive stream out of the optimum temperature region. It was also found that a cocurrent injection mode facilitated smooth additive feeding and high NO conversion, so all tests were conducted in a cocurrent mode. After nozzle selection, performance optimization tests were conducted. Methanol, H20 2, and the mixture were tested as a function of injection temperature at the three initial NO levels ([NO]J. Results are presented in Figure 2. Figure 2a shows NO remaining at different temperatures and at [NOli = 200 ppm. This and other graphs represent percent of NO remaining defined as a ratio of NO exhaust level to its initial concentration, [NOlex/[NOli 100%. From 90 to 98% NO-to-N02 conversion was achieved with an additivelNO Molar Ratio (MR) of 1.5. Maximum NO removal was achieved at 750-820 K for injection of H20 2 and the H20/CH30H mixture, and at 850-930 K for CH30H injection. NO-to-N02 conversion of 90-96% was achieved with MR equals 1.5. Maximum performance, about 96-98%, was observed with the 1: 1 H20/methanol mixture for an initial NO level of 70 ppm, in this test the NO concentration was decreased from 70 to 2 ppm. In all tests methanol gave slightly greater maximum NO conversion than H20 2, however, their mixture 5 - |