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Show Presented at 2012 AFRC Annual Meeting, September 5-‐7, Salt Lake City, UT © 2012 ClearSign Combustion Corp. all rights reserved 5 2. Flame Stability. In another example, ECC technology enhances flame stability (Figure 6). Such stability is important for reasons of safety, turndown, and flame anchoring in low-‐NOx and ultra-‐low-‐NOx burners. (a) ECC Technology Off (b) ECC Technology On Figure 6. Flame Stabilization with ECC Technology. An unstable flame is tentatively prevented from blowing out by a large bluff body (a). The flame is charged with a proprietary waveform through a charge rod and is immediately anchored to an ECC flame holder (b); the bluff body is no longer needed. Additional patent-‐pending techniques allow the flame anchor position to be electronically adjusted in space along any continuum traversing a flammable mixture. 3. Emissions suppression. By varying the flame anchoring position, NOx was reduced from more than 100 ppm to 15 ppm at 2% O2 and 1200 °F without detectable CO or the need for complicated burner internals or external FGR. NOx suppression is likely enhanced by the increased fuel/air/flue gas mixing and flame homogenization. Such homogenization tends to reduce peak flame temperatures and thermal NOx. 4. Directed heat transfer. ECC technology may be used to direct thermal flow toward (or away from) various surfaces. In the former case, heat transfer is enhanced. Figure 7 shows a simulation representing enhanced heat transfer to surface such as boiler or process tubes in a furnace. ClearSign has also demonstrated that ECC technology can be used to repel heat from a surface. Such technology has application to kiln walls, gas turbine blades, and other surfaces for which heat transfer must be minimized. Early experiments with a a turbine blade simulator have shown significant decrease in heat transport to the blade surface. Figure 6 gives Schlieren images for hot combustion gases before and after the addition of an electric field. charge'rod' bluff'body' ECC'flame'' holder' |
