|Title||Progress and Recent Advances Using Electrodynamic Combustion Control (ECC)-Colannino, Joseph|
|Spatial Coverage||Kauai, Hawaii|
|Subject||2013 AFRC Industrial Combustion Symposium|
|Description||Paper from the AFRC 2013 conference titled "Progress and Recent Advances Using Eletrodynamic Combustion Control (ECC) by Joseph Colannino.|
|Rights||No copyright issues|
© 2013 ClearSign Combustion Corp. all rights reserved Computer Controller ±10 V ±40 kV <0.1% of thermal Input Power Amplifier Electrode(s) Combustion system Progress and Recent Advances Using Electrodynamic Combustion Control (ECC™); Joseph Colannino, CTO; ClearSign Combustion Corporation In 2012, ClearSign reported to the American Flame Research Council a number of effects and the filing of more than 35 patents. Recent progress (1Q 2013) includes an expanded intellectual property portfolio of more than 100 patents pending for • enhancing and stabilizing combustion reactions, including o increasing flame speed o strengthening flame anchoring o enabling virtual anchoring • dramatically reducing emissions including reductions in o NOx o CO o Soot and particulate matter • beneficially altering flame character including o reducing flame height o increasing luminosity • beneficially altering heat transfer including o enhancing heat transfer to tube surfaces in process heaters and boilers o reducing heat transfer to turbine blade surfaces o eliminating of hot spots Many such effects are enabled by applying an electric field to electrodynamically affect the combustion process. In one basic embodiment, a computer controlled waveform of ±10 V is ported to a power amplifier, amplified to ±40 kV, and delivered to a flame (Figure 1). Figure 1. One Embodiment of ClearSign's ECC Technology. A computer controlled signal is amplified to ±40 kV. The resulting electric field influences ions in the combustion process to create a wide variety of beneficial effects but uses very low power (<0.1% system thermal power). For Presentation to the AFRC Kauai, HI Page 2 Simplex™ Flame Holder Duplex™ Flame Holder Waveform Generator Charge Rod Fuel Nozzle ±20kV ~5 W Simplex™ Flame Holder Duplex™ Flame Holder Waveform ±20kV Generator ~5 W Charge Rod Fuel Nozzle 0" 2" 4" 6" 8" 10" 12" 0" 20" 40" 60" 80" 100" 120" 0" 2" 4" 6" 8" 10" 12" 14" 16" 18" 20" CO,"ppm,"Corrected"to"3%"O2" 5"ppm"NOx" NOx,"ppm,"Corrected"to"3%"O2" Run"Time,"Min" Emissions"Performance"of"DuplexTM"Burner" 1600"F,"3%"O2" ! Duplex Operation Enabled Although the voltage is high, the current is generally in the μA range with overall power measured in Watts; in general, <0.1% of the thermal power is required in the form of electrical energy to beneficially influence the combustion process. Ions and electrons in the flame respond to the electric field. Although only the charged particles respond, their collision with surrounding species results in bulk flow. By modulating the waveform, interesting effects may be obtained including enhancing and stabilizing combustion reactions, reducing emissions, and beneficially altering flame character and improving heat transfer. Recent advances include strengthening of many of these effects and the discovery of new effects. In one experiment, a high NOx flame (120 ppm) as enabled electronically to generate <5 ppm (Figure 2). Figure 3 gives a strip chart of the before and after emissions. (a) (b) Figure 2. ClearSign's Duplex™ Burner. NOx is reduced from 120 ppm to <5 ppm by the following means. A charged flame is electronically anchored to a simple nozzle via electronic forces and generates high NOx (120 ppm). The flame is then electronically transferred to a Duplex™ flame holder. The resulting NOx is sub 5 ppm at 3% excess oxygen and 1600 °F with no external flue gas and virtually no CO (Figure 3). Figure 3. Emissions Performance for the Duplex Burner. NOx drops precipitously from 120 ppm to <5 ppm. Heat release is 250,000 Btu/h with a furnace temperature of 1600 F and 3% excess O2. No external flue gas recirculation is required or used. For Presentation to the AFRC Kauai, HI Page 3 Direct Charging Flame on Flame (FOF™) Remote Charging Using this method, NOx reductions to less than 3 ppm have now been demonstrated at ~200,000 Btu/hr in a 1650 °F furnace with 1 to 3% excess oxygen. A Duplex burner oriented horizontally may also be installed in a typical firetube boiler. In order to prove this concept, a boiler simulator has been built (Figure 4). Figure 4. Boiler Simulator. A boiler simulator (shell and tube construction) is shown that will be used for proof of concept testing of the Duplex Burner. The burner is to be fired horizontally from left to right as pictured. Sight ports (12 of 24 visible) will allow visual and camera access to the flame volume. Final NOx performance appears to be independent of initial starting NOx. For example, a staged-‐fuel burner generated emissions of 40 ppm, but NOx again fell to <3 ppm when Duplex flame holding was activated. These results have been repeated for a variety of heat releases and initial burner geometries to 300,000 Btu/h thus far. Scale up is continuing and is expected to include heat releases to 1 MMBtuh before year end. A 5 MMBtuh furnace is currently under construction for further scale-‐up and testing of ECC-‐enabled effects and a variety of patent pending methods have been developed for charging the flame (Figure 5) including directly contacting the flame with an electrode; using a pilot flame to convey charge to a main flame; conveying charge to the main flame through space by an ion beam. ClearSign has successfully employed all of the above methods to successfully enhance stability for heat releases up to 1 MMBtuh. (a) (b) (c) Figure 5. Some patent-‐pending methods for charging the flame. Flames contain ions and electrons in equilibrium. However, electrons are easily donated or removed from a flame electronically to leave a charged volume amenable to manipulation by electric fields. For example, the flame may be charged by direct contact with an electrode (a) or a charged pilot flame may convey charge to a larger main flame (b). Additionally, flames can be remotely charged through space (c). sight port end view side view water jacket fired space For Presentation to the AFRC Kauai, HI Page 4 ! 1! ! ! ! (a)!ECC!Technology!Off! (b)!ECC!Technology!On! ! 1! ! ! ! ! ! 1! ! ! ! ! ECC Technology Off ECC Technology On Toroid& Average&& Flame& Height& Coulombic& Force& ECC Technology Off ECC Technology On Investigations continue with natural gas, propane, blended gaseous fuels, liquid fuels, and solid fuels such as biomass, tire derived fuel, and municipal solid waste. For example, soot formation has been dramatically suppressed (Figure 6), flame height has been halved and flame luminosity increased (Figure 7), flue gases attracted or repelled from surfaces (Figure 8), and temperatures more evenly distributed along fired tubes (Figure 9). (a) (b) Figure 6. OFF vs. ON: soot formation. A bench-‐scale apparatus combusts a batch of solid fuel blend comprising tires, charcoal, and biomass with attendant smoke and particulate emissions - upper panel (a). The lower panels show the fly ash collected. Then ECC Technology is switched on, attenuating the smoke and resulting in ash that is visually carbon free - lower panel (b). (a) (b) Figure 7. OFF vs. ON: flame height and luminosity. A propane flame shows reduced flame height and increased luminosity when ECC Technology is ON (b) versus OFF (a). Columbic forces from an upper toroid are responsible for shrinking the flame height while an electric field enhances the luminosity. For Presentation to the AFRC Kauai, HI Page 5 135 °F Flue Gas Exit Temp = 250 °F 195 °F Flue Gas Exit Temp = 220 °F (a) (b) Figure 8. OFF vs. ON: directed heat transfer. Infrared thermography shows the normal tendency of a flue gas plume from a propane flame to rise vertically (a). However, with ECC Technology ON (b) the plume is pulled toward a grounded or charged surface. The plume can also be repelled with a change of polarity. (a) (b) Figure 9. OFF vs. ON: thermal redistribution. Infrared thermography shows a hot spot developing in a fired tube (a). When ECC Technology is turned ON (b) the heat distribution is homogenized over the tube surface and the exit temperature is reduced as more heat is transferred through the tube wall. Switching off ECC Technology restores the original maldistribution. Scale up is proceeding at a rapid pace and has scaled from 0.1 MMBtuh to 1 MMBtuh in less than two years, with testing at 5 MMBtuh scheduled to begin before year end 2013 (Figure 10). ECC Technology has been shown to require very low electrical power consumption corresponding to less than one tenth of one percent of the equivalent thermal power For Presentation to the AFRC Kauai, HI Page 6 100 2008 1,000 Firing Rate, MBtuh 10,000 10 2009 2010 2011 2012 2013 2014 Time, Yr Btu/h 25 Btu/h 5 Btu/h 400 Btu/h 1,000 Enhanced Heat Transfer Btu/h Q1 2008 Q3 2008 Q4 2012 Q1 2011 Particulate Reduction Flame Shaping Enhanced Luminosity 5,000 100 Enhanced Stability Q2 2011 Q4 2013 treated. Such a requirement appears to be scale invariant with all heat releases studied thus far (up to 1 MMBtuh). Such low power requirements have allowed ClearSign to shrink the size and cost of the power amplifier by more than three orders of magnitude (Figure 11). Figure 10. Rapid Scale-‐up. ECC Technology has been scaled up from 0.1 MMBtuh to 1.0 MMBtuh between 2011 and 2013, with a 5 MMBtuh unit scheduled to come on line before the close of 2013. Figure 11. Old and new amplifier. ClearSign's Dr. Igor Krichtafovitch shown standing in front of a conventional high voltage amplifier capable of delivering 40 kV, and holding ClearSign's new version in his hand (circled), also capable of delivering 40 kV. The amplifier represents a 1000-‐fold reduction in volume and cost. For Presentation to the AFRC Kauai, HI Page 7 In addition, the new amplifier is intrinsically safe, with output current limited to non-‐lethal levels (< 5 mA), and "inertialess" with automated shut down in nanoseconds in the case of accidental human contact. The amplifier has a universal power supply that automatically recognizes and accepts wall current anywhere in the world between 100 and 250 VAC and 50 to 60 Hz. Conclusions ClearSign's ECC Technology has been shown to enable or assist the following benefits. • NOx reduction to less than 3 ppm with the following feature set: o independent of starting NOx, o with flame length reduced up to 90%, o with turndown preserved, o without external flue gas recirculation, o without additional excess air (excess oxygen remains in the customary 1-3% range), and o without increased CO emissions • Dramatic reductions of soot and particulates. • Beneficial control over flame shape and luminosity. • Directed heat transfer to or away from target surfaces. • Beneficial thermal redistribution over conductive surfaces such as boiler and process tubes. ClearSign's intellectual property comprises more than 100 patents pending. Prototype systems have been scaled up to 1 MMBtuh. Validation at 5 MMBtuh is scheduled to begin this year.