APPARATUS AND METHOD FOR PROVIDING ELECTRICAL COMBUSTION CONTROL TO A BURNER

Abstract

Technologies are provided for a method and an adaptor for introducing electricity into a combustion chamber, for the purpose of electrical flame or combustion control. The adaptor may be placed between a conventional burner assembly and a conventional combustion chamber wall. The adaptor includes an aperture for admitting electricity into the combustion chamber.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation-in-Part Application of co-pending U.S. patent application Ser. No. 14/827,390, entitled “ADAPTOR FOR PROVIDING ELECTRICAL COMBUSTION CONTROL TO A BURNER,” filed Aug. 17, 2015 (docket no. 2651-110-03). U.S. patent application Ser. No. 14/827,390 claims priority benefit from U.S. Provisional Patent Application No. 62/037,962, entitled “ELECTRICAL PASSTHROUGH ADAPTOR FOR COMBUSTION CONTROL”, filed Aug. 15, 2014 (docket no. 2651-110-02), now expired.

The present application is also a Continuation-in-Part Application of co-pending International PCT Application No. PCT/US2019/039475, entitled “COMBUSTION SYSTEM INCLUDING A COMBUSTION SENSOR AND A PLASMA GENERATOR,” filed Jun. 27, 2019 (docket number 2651-342-04). International Patent Application No. PCT/US2019/039475 claims priority benefit from co-pending U.S. Provisional Patent Application No. 62/821,543, entitled “COMBUSTION SYSTEM INCLUDING A COMBUSTION SENSOR AND A PLASMA GENERATOR,” filed Mar. 21, 2019 (docket number 2651-342-02). International Patent Application No. PCT/US2019/039475 also claims priority benefit from U.S. Provisional Patent Application No. 62/694,890, entitled “INDUSTRIAL BURNER INCLUDING A LOW TEMPERATURE PLASMA STABILIZED FLAME HOLDER,” filed Jul. 6, 2018 (docket number 2651-328-02), now expired. International Patent Application No. PCT/US2019/039475 also claims priority benefit from U.S. Provisional Patent Application No. 62/691,469, entitled “BURNER SYSTEM INCLUDING A PERFORATED FLAME HOLDER AND ELECTRO-CAPACITIVE SENSING,” filed Jun. 28, 2018 (docket number 2651-335-02), now expired. International Patent Application No. PCT/US2019/039475 also claims priority benefit from co-pending U.S. Provisional Patent Application No. 62/756,468, entitled “PILOT BURNER WITH A FLAME SENSOR,” filed Nov. 6, 2018 (docket number 2651-323-02). International Patent Application No. PCT/US2019/039475 also claims priority benefit from U.S. Provisional Patent Application No. 62/702,475, entitled “VARIABLE COMPOSITION GAS MIXTURE SENSOR,” filed Jul. 24, 2018 (docket number 2651-333-02), now expired.

Each of the foregoing applications, to the extent not inconsistent with the disclosure herein, is incorporated by reference.

BACKGROUND

About two-thirds of global energy consumption occurs as hydrocarbon fuel combustion in boilers, furnaces, kilns, and turbines. A small percentage of consumption is provided by combustion of other fuels such as hydrogen and carbon monoxide. The energy released by the combustion is used to generate electrical power and to provide heat for a wide range of industrial and commercial purposes.

In conventional furnaces, boilers, process heaters, and the like, combustion air and fuel are supplied to a “burner assembly”. The part that outputs fuel to the combustion chamber is called a fuel nozzle (in the case of a non-premixing nozzle). Air can be forced air or natural draft. In many burner assemblies, the air and fuel are admitted in close proximity to one another. Another part of some conventional burner assemblies is a flame holder. Compared to usually-seen flames, the fuel and air velocities in an industrial burner assembly may tend to be too high to hold the flame against the fuel nozzle (or for the flame to be held in an equilibrium position where the flame speed is equal to the fuel and air velocity). A burner assembly manufacturer may therefore add an eddy-producing flame-holder structure to cause the flame to be held in a known position. In some burner assemblies, the flame holder is a refractory material that extends into the combustion chamber; such a refractory flame holder is often referred to as a burner tile.

This conventional structure works adequately but could be improved by reducing emissions and by improving the combustion process. It has been found by the inventors that electricity can be applied to the combustion reaction, and the characteristics of the combustion reaction can be selected according to electrode geometry and location, as well as electric signal characteristics (e.g., AC vs. DC, frequency, waveform sharpness, phase relationships, and voltage), to improve combustion. However, conventional devices may suffer from limited provisions for passing electrical signals, especially high-voltage signals, to the combustion chamber.

SUMMARY

According to embodiments, methods and apparatuses for introducing electricity to a combustion chamber heated by a burner assembly are provided. The burner can be used to drive a gas and/or steam turbine, produce hot water or steam, or drive an endothermic reaction in an industrial process, for example. More particularly, embodiments include an adaptor accessory mounted between the burner assembly and a wall of a combustion chamber. The adaptor includes a provision for passing an electrical conductor for transferring electricity from an electrical source outside of the combustion chamber to one or more electrodes inside the combustion chamber.

Conventional mounting of a burner assembly to the wall of the combustion chamber (e.g., the floor of an up-fired furnace or a front wall of a package boiler) may involve bolts or other fasteners that fasten the burner assembly to the combustion chamber wall. According to an embodiment, the inventors contemplate replacing conventional fasteners with hollow fasteners that include an insulated passage for a high voltage electrical conductor. According to another embodiment, the inventors contemplate an adaptor including a spacer configured to fit between the burner assembly and the combustion chamber wall. One or more electrical conductors convey electricity through a wall of the spacer. Optionally the spacer can include one or more additional electrical conductors for passing sensor signals and the like through the wall of the spacer.

According to an embodiment, a combustion system includes a combustion chamber wall defining a combustion chamber and a burner assembly configured to operatively couple to an exterior of the combustion chamber wall and to support a combustion reaction inside the combustion chamber. An adaptor is configured to couple between the burner assembly and the combustion chamber wall. The adaptor includes an adaptor body defining an aperture configured to pass an electrical conductor therethrough. The electrical conductor is configured to carry a high voltage electrical signal from outside the combustion chamber wall to inside the combustion chamber through the adaptor body aperture. In an embodiment, the aperture is configured to receive an electrical bushing and the electrical bushing is configured to carry the electrical conductor.

According to an embodiment, an adaptor for a combustion system includes an adaptor body defining a) an aperture configured to pass an electrical conductor therethrough, b) a proximal flange coupled to or integral with the adaptor body, the proximal flange defining a pattern of bolt holes selected to couple to a mounting flange of a burner assembly, and c) a distal flange coupled to or integral with the adaptor body, the distal flange defining a pattern of bolt holes selected to couple to a mounting surface of a combustion chamber wall. The adaptor can be structured to pass a wire carrying a high voltage electrical signal through the aperture without electrical short or open circuit. The high voltage electrical signal can be provided by a power supply external to the combustion chamber, and the high voltage signal can be used inside the combustion chamber to modify or control an aspect of a combustion reaction supported by the burner.

According to an embodiment, a method includes providing a combustion chamber wall defining a combustion chamber, providing a burner assembly configured to operatively couple to an exterior of the combustion chamber wall and configured to support a combustion reaction inside the combustion chamber, providing an adaptor configured to couple between the burner assembly and the combustion chamber wall, wherein the adaptor further may include an adaptor body defining an aperture configured to pass an electrical conductor therethrough. The method may further include coupling the burner assembly to the combustion chamber wall via the adaptor. The method can further include passing the electrical conductor through the aperture and/or providing an electrical bushing, between the adaptor and the electrical conductor, in the aperture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded diagram of a combustion system including an adaptor, according to an embodiment.

FIG. 2 is a perspective view of an adaptor for mounting between a burner assembly and a wall of a combustion chamber, according to an embodiment.

FIG. 3A is an exploded perspective view of an adaptor for mounting between a burner assembly and a wall of a combustion chamber, according to another embodiment.

FIG. 3B is a detailed view of a portion of the adaptor of FIG. 3A, according to an embodiment.

FIG. 4 is a view of a coupling, according to an embodiment.

FIG. 5 is a partial cross-section view of a coupling, according to an embodiment.

FIG. 6 is a flowchart showing a method, according to an embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Other embodiments may be used and/or other changes may be made without departing from the spirit or scope of the disclosure.

FIG. 1 is an exploded diagram of a combustion system 100, according to an embodiment. An embodiment relates to a combination of a burner assembly 104 and a combustion chamber wall 106. A combustion chamber 107 may be, for example, the interior or furnace of a package boiler, a custom boiler, a process heating furnace, or other known heating device. In an embodiment, the combustion chamber wall 106 can include a steel shell or a steel shell with a lining of refractory high-temperature insulation.

The inventors are primarily concerned with combinations in which the burner assembly 104 is attachable and detachable from the combustion chamber wall 106. Conventionally, the burner assembly 104 and the combustion chamber wall 106 are removably fastened directly to each other by bolts.

Control of combustion by high-voltage electricity inside the combustion chamber 107 has been found by the applicants to have strong and beneficial effects on flame shape and flame chemistry. The use of electricity for flame control is described in co-pending U.S. application Ser. No. 14/029,804, entitled “CLOSE-COUPLED STEP-UP VOLTAGE CONVERTER AND ELECTRODE FOR A COMBUSTION SYSTEM”, filed Sep. 18, 2013 (docket no. 2651-050-03); Ser. No. 14/144,431, entitled “WIRELESSLY POWERED ELECTRODYNAMIC COMBUSTION SYSTEM”, filed Dec. 30, 2013 (docket no.: 2651-159-03); and Ser. No. 14/179,375, entitled “METHOD AND APPARATUS FOR DELIVERING A HIGH VOLTAGE TO A FLAME-COUPLED ELECTRODE”, filed Feb. 12, 2014 (docket no.: 2651-111-03); the contents of which are each incorporated herein by reference.

FIG. 1 depicts the burner assembly 104, the combustion chamber wall 106, a combustion controller 108, and an adaptor 109 configured for insertion between the burner assembly 104 and the combustion chamber wall 106, so as to provide output of fuel and air by the burner assembly 104 and input of electrical energy through an opening 116 into the combustion chamber 107, according to an embodiment.

The combustion system 100 includes the combustion chamber wall 106 defining the combustion chamber 107. The burner assembly 104 is configured to operatively couple to an exterior of the combustion chamber wall 106 and to support a combustion reaction inside the combustion chamber 107. For example, when coupled directly together, the burner assembly 104 and combustion chamber wall 106 can form a conventional combustion system. One object of embodiments described herein is to allow retrofitting such a conventional combustion system to an upgraded combustion system wherein high voltage electrical energy is applied to one or more electrodes 110 proximate to a combustion reaction inside the combustion chamber 107.

In an embodiment, the adaptor 109 is configured to couple between the burner assembly 104 and the combustion chamber wall 106. The adaptor 109 can include an adaptor body defining an aperture 118 configured to pass an electrical conductor therethrough. The electrical conductor can be configured to carry a high voltage electrical signal from outside the combustion chamber wall 106 to inside the combustion chamber 107 through the adaptor body aperture 118.

The aperture 118 can be configured to receive an electrical bushing 214 (shown in FIG. 2) configured to carry the electrical conductor.

Also shown in FIG. 1 are other parts of the combustion controller 108 configured to control, or which may optionally be integrated with, a power supply 112 configured to provide a high voltage to a flame-controlling electrode 110. Optionally, a sensor 114 may be operable to provide, to the combustion controller 108, information about combustion inside the combustion chamber 107 (shown by dashed lines in FIG. 1), whereby the combustion controller 108 may provide flame-control with feedback from the sensor 114. It will be understood that the adaptor 109 may have several functions, including mechanical attachment of the burner assembly 104 to the combustion chamber wall 106, sealing against leakage of air, fuel, or flame, passing electrical high voltage and/or current from outside to inside the combustion chamber wall 106 or back, mechanically supporting the electrodes 110 within the combustion chamber 107, etc.

In an embodiment, portions of the electrodynamic combustion system 100 may optionally include the power supply 112, which can be configured as a portion of a voltage controller 108. The voltage controller 108 may include analog circuitry, a processor, and/or a computer, and may adjust the voltage of the power supply 112 according to timing, flame feedback, predetermined criteria, etc. If a processor or a computer is included, it will be operated as a programmed computer, and when not running may store the program in a non-transitory medium. In addition to the illustrated power supply (and/or current source) 112 disposed outside of the combustion chamber 107 or the combustion chamber wall 106, there may also be provided other sources of voltage or current, or circuit components, disposed inside the combustion chamber 107 or on its wall 106; for example, transformers, rectifiers, and the like may be disposed inside the adaptor 109 and/or inside the combustion chamber wall 106, or in the combustion chamber 107 or in a burner tile, and may act as functional parts of the electrodynamic combustion system 100. Such internal components might, for example, permit the electricity arriving at the adaptor 109 from the electrodynamic combustion system power supply 112 to be replaced or augmented by a source of relatively low-voltage electricity, which would increase safety; they might include a voltage converter that may include a transformer, a switching power supply, a charge pump, and/or a voltage multiplier, for example.

The electrodynamic combustion system power supply 112 may produce electricity selected to create electric fields and/or provide charge to influence the combustion reaction in the combustion chamber 107.

The adaptor 109 also includes an electrical aperture 118. This electrical aperture 118 may provide a path for electrical connection between elements outside the combustion chamber 107, such as the power supply 112, and elements inside the combustion chamber 107, such as the electrode 110. Optionally, one or more sensors, or other internal electrical components 114 may also be electrically connected to elements outside the combustion chamber 107. In this way, a combustion reaction inside the combustion chamber 107 is controllable by the power supply 112 via an induced charge, voltage, current or electric field in the vicinity of the combustion reaction inside the combustion chamber wall 106. One or more apertures 118 may be provided for various flame- or combustion-control voltages and/or sensor signals.

According to an embodiment, the inventors contemplate a variant of the adaptor 109 wherein only low voltage signals are passed between outside the combustion chamber 107 and inside the combustion chamber 107.

In an embodiment, the electrical aperture 118 is configured to pass one or more electrical connection elements to a plasma generator positioned within the combustion chamber 107. The plasma generator is configured to generate a plasma within the combustion chamber 107. The plasma can assist in igniting a combustion reaction within the combustion chamber 107. Additionally or alternatively, the plasma can enhance a stability of a combustion reaction within the combustion chamber 107.

The plasma generator may be driven to form a high temperature plasma to ignite a combustion reaction within the combustion chamber 107 during an ignition phase, and then form a low temperature plasma to stabilize the combustion reaction during an operation phase.

In one embodiment, the plasma generator helps to stabilize the combustion reaction. The plasma generator can help to stabilize the combustion reaction by generating a low temperature plasma in the vicinity of the combustion reaction. The low temperature plasma can energize a mixture of fuel and oxidant to promote stable combustion of the fuel and oxidant mixture. For example, if the combustion reaction is unstable at a selected combustion location, the plasma generator can generate the low temperature plasma to energize the fuel and oxidant mixture to promote stable combustion of the fuel and oxidant mixture.

Generating the low temperature plasma can include generating and outputting oxygen radicals. Generating the low temperature plasma can include ejecting electrons from one or more electrodes 110 of the plasma generator.

In one embodiment, the plasma generator can output a high temperature plasma including a gaseous mixture of ions and electrons. The high temperature plasma can help ignite the combustion reaction when the combustion reaction is absent.

In one embodiment, the plasma generator includes multiple electrodes 110 connected to the power supply 112 by electrical connection elements passed through the electrical aperture 118. In one embodiment, the adaptor 109 includes multiple electrical apertures 118 that each receive on or more electrical connection elements. Accordingly, the adaptor 109 can pass multiple electrical connection elements between plasma generation electrodes 110 within the combustion chamber 107 and the power source 112 and/or the combustion controller 108.

The power source 112 may drive electrodes 110 of the plasma generator to generate the plasma. The power source 112 may include a pulsed power source 112 that may be operated to output nanosecond pulses such that the electrodes of the plasma generator are driven to generate the low temperature plasma. The low temperature plasma may produce plasma enhanced maintenance of continuous ignition of the fuel and oxidant mixture.

In one embodiment, the plasma generator includes first and second plasma generation electrodes positioned within the combustion chamber 107. The power source 112 has first and second output terminals. The first and the second plasma generation electrodes are respectively operatively coupled to the first and the second output terminals by electrical connectors passed through the one or more electrical apertures. The power source 112 and the first and the second plasma generation electrodes may be operable to cause a low temperature plasma to form within or adjacent to a selected location for the combustion reaction.

FIG. 2 shows an embodiment 200 of the adaptor 109 (shown in FIG. 1), which may, in this case, include a short tube 202 that can be disposed between the burner assembly 104 (shown in FIG. 1) and the combustion chamber 107 (shown in FIG. 1). The adaptor 109 may also include a proximal flange 204 and a distal flange 206 configured to respectively bolt to the burner assembly 104 and the combustion chamber wall 106 (shown in FIG. 1).

The aperture or apertures 118 may be located outside of a primary air flow can 208 that is disposed inside the adaptor 109 (generally, this is a smaller tube inside the tube 202 illustrated in FIG. 2, and optionally parallel though not necessarily coaxial). The primary air flow can 208 may be larger, the same, or smaller in diameter than an outer diameter of the burner assembly 104. According to an embodiment, the inventors contemplate an aperture 118 that conveys an electrical signal (e.g., high voltage signal) through a wall of a tube 202 that also acts as an airflow passage. In some embodiments, the tube 202 may define a mixing chamber for a premix or partial premix section. In other embodiments, the tube 202 may define a secondary air flow passage that is separated from primary combustion air by the primary air flow can 208. In other embodiments, the burner may not use any secondary combustion air and the primary air flow can 208 may be omitted.

FIGS. 1-2 show that the electrode 110 may be attached to the adaptor 109. However, the electrode 110 may also be mounted to the inside of the combustion chamber 107 or elsewhere on the combustion chamber wall 106, in which case the electrode 110 may be electrically connected to a conductor passing into the combustion chamber 107 via the adaptor 109.

To be able to assemble the electrodes 110 first and then add the burner assembly 104, a person skilled in the art may need to add an open-ended slot 210 in the primary air flow can 208 that will allow the primary air flow can 208 to be inserted without mechanical interference with the electrode 110. In an embodiment, the inventors contemplate providing the adaptor 109 as a kit including a cutting or drilling template for specifying modification(s) to be made to the primary air flow can 208 or other component of the burner assembly 104. However, one purpose for the adaptor 109 is to allow a standard burner assembly 104 (e.g., fuel source, fuel nozzle, air source, air damper, blower, premixer, and/or controller, with associated parts) to be used. Hence, the inventors contemplate looping the electrodes 110 and/or leads from the aperture 118 around the distal end of the primary air flow can 208 when the primary air flow can 208 is in place (for systems that include primary air flow cans 208). In this way, there is no change to the burner assembly 104 and no mechanical interference. Thus, the adaptor 109 includes cases of the electrode 110 passing through the slot 210 or fitting in the primary air flow can 208, and cases of the electrode 110 remaining outside the primary air flow can 208.

In this embodiment, the feed-through or aperture 118 conducts electricity or signals through the tube 202 wall so as to electrically connect the power supply 112 (shown in FIG. 1) to the electrode or electrodes 110, which may project toward and/or into the combustion chamber 107. In an embodiment, this aperture 118 further includes a central conductor 212 inside a surrounding insulator 214. This surrounding insulator 214 might be a high-temperature insulator such as ceramic, air, or vacuum.

It is known in the art that the primary air flow can 208 may separate primary from secondary combustion air. Consequently, no matter where the electrode 110 is (inside or outside the primary air flow can 208), it likely is in combustion air flow. If the primary air flow can 208 is provided or used, then the flame may include a primary flame that is supported by fuel and primary combustion air supplied inside the primary air flow can 208, while the region in between the primary air flow can 208 and the inside of the tube 202 contains secondary combustion air but not substantial fuel. In this case, it may be practical to pass an electrode through an open hole or opening in the side of the tube 202. That is, the insulator 214 surrounding the conductor 212 might be omitted and replaced with air, if the resulting opening were not to upset the airflow balance of the combustion, and if the central conductor 212 were mechanically supported in such a way that it would not touch the edges of the hole in the tube 202.

The conductor 212 may in some instances be integral with the electrode 110.

In embodiments, the distal flange 206 of the adaptor 109 may be fastened to the combustion chamber wall 106 with threaded fasteners (i.e., bolts, studs and nuts, or screws) deployed in a substantially circular layout onto a steel plate forming the outer surface of the combustion chamber wall 106 (shown in FIG. 1). In such an embodiment, the proximal and the distal flanges 204, 206 of the adaptor 109 may have the same layout of holes 216 in each flange. The flange holes 216 can be aligned with one another, so that the fasteners can proceed straight through both flange holes 216, or they can be offset angularly around an axis of the short, flanged tube 202 so as to allow better access to bolt heads or nuts of the respective fasteners.

The proximal and the distal flanges 204, 206 are respective examples of a proximal mount (adjacent the burner assembly 104) and a distal mount (adjacent the combustion chamber wall 106).

In an embodiment, the axial length of the flanged tube 202 of FIG. 2 may be minimized to minimize a change in distance of extension of the fuel nozzle and/or flame holder into the combustion chamber 107. It is expected that the burner assembly 104 can be moved away from the combustion chamber wall 106 and will still perform as intended. However, change from a nominal design (i.e., without the electrical feedthrough adaptor 109) may desirably be minimized to avoid any possible complications, which suggests minimizing the height of the illustrated adaptor collar (the axial length of the tube 202 plus thicknesses of the proximal and the distal flanges 204, 206).

In one embodiment, the flanged tube 202 may include multiple electrical apertures 118 each configured to pass one or more conductors 212 into the combustion chamber 107. In one embodiment, an electrical aperture 118 can pass multiple electrical conductors that are electrically insulated from each other, for example by each being coated in a insulator material.

The adaptor 109 can pass one or more conductors to one or more plasma generation electrodes positioned within the combustion chamber 107, as described in relation to FIG. 1.

FIGS. 3A and 3B show an embodiment 300, 301 of the adaptor 109 (shown in FIG. 1) consisting essentially or primarily of flat plates or sheets of metal and insulation, which is deployed as would be a gasket between the burner assembly 104 (shown in FIG. 1) and the combustion chamber wall 106 (shown in FIG. 1). This gasket-like construction may minimize the thickness of the adaptor 109. The adaptor 109 may include two insulating plates 302 and 304, and between these insulating plates 302 and 304 can be a compound plate 306 that is made of contiguous sections of insulation and conductive metal, pieced together akin to a jigsaw puzzle.

The insulation sections or portions of the compound plate 306 surround bolt holes 308 (for simplicity of illustration, only one is shown, in FIG. 3B, but they are analogous to the flange holes 216 of FIG. 2) to provide insulation from grounded bolts, and may substantially surround metal portions 310 that are used to transfer electricity or signals through the adaptor 109, and which embody the aperture 118 of FIG. 1. The metal portion 310 of the compound plate 306 may be fixed to the electrode 110 (shown in cross section in FIG. 3B) and support it for projection into the combustion chamber 107 (shown in FIG. 1) beyond the combustion chamber wall 106. At the opposite end the metal portion 310 may include a fitting 312 onto which an insulated high-voltage wire can be snapped, as an example; other types of electrical connection can be used, for example, solder.

When bolts through the bolt holes 308 are tightened, the metal portion 310 of the compound plate 306 can be held tightly by compressive force and thereby hold the electrode 110 immobile. In an embodiment, the sandwich of insulating plates 302-304 may be encased in additional metal plates 314 and 316, for mechanical strength. These may be omitted if the burner assembly 104 and the combustion chamber wall 106 are rigid enough and a compression-force annulus or area between the burner assembly 104 and the combustion chamber wall 106 is wide enough to provide sufficient support for the metal portion 310 and the electrode 110 fixed to it.

In an embodiment, the inventors contemplate applying high voltages of up to or beyond about 20 kV. In another embodiment, the inventors contemplate applying high voltages up to or beyond 40 kV. This implies that the insulating plates 302, 304 might need to be only a few millimeters thick, and that the entire sandwich might be as little as a fraction of an inch in thickness, thereby shifting the position of the burner assembly 104 relative to the combustion chamber wall 106 by only that amount, as compared to its position without the adaptor 109.

While only one metal portion 310 is illustrated in FIGS. 3A and 3B, more than one can be used. If several are provided to share a common voltage, then these may be connected inside the bore of the adaptor 109 or by conductive segments or wires in the compound plate 306.

FIG. 4 illustrates a third embodiment of the adaptor 109 of FIGS. 1-3A that may employ, as the aperture 118, hollow bolts 400 in place of conventional bolts used to join the burner assembly 104 and the combustion chamber wall 106. These hollow bolts 400 constitute the adaptor 109 and also the electrical aperture 118. Like conventional bolts that might be used to attach a burner assembly to a combustion chamber, the hollow bolts 400 include a cylindrical portion 402 with a head 404 and threads 406. In this third embodiment, each bolt 400 used to secure the burner assembly 104 to the combustion chamber wall 106 has a central bore which contains a central (preferably axial) conductive wire or rod 408, surrounded by an electrically insulating tube 410. To insulate 20-40 or more kV, insulation such as polyethylene or ceramic may need to be only thicker than about 2 mm, so this embodiment can be incorporated into bolts 400 of ordinary size, such as half-inch-diameter bolts. The central conductive wire or rod 408 can connect on the outside to the power supply 112 of the electrodynamic combustion system 100, and on the inside can be electrically coupled to the electrode 110, by conventional means such as the illustrated male threads 406. This embodiment can be combined with the “tile anchors” often used to hold a burner tile. The illustrated bolt 400 is not only exemplary of other conventional threaded fasteners that might be replaced, such as studs and screws, but also exemplifies fasteners in general, such as non-threaded fasteners. The inventors contemplate replacing conventional hardware of any sort, whether used to fasten a burner assembly, a burner assembly tile, or another part of a combustion device.

This embodiment has several advantages. First, the burner assembly 104 offset as compared to that without is negligible. Second, the electrode 110 can be fastened directly to the inner threaded end of the central conductive rod 408, or, to the threads 406 at the inner ends of the bolts 400 by insulating supports that thread onto the bolt threads 406, either of which will provide good mechanical support if the electrodes 110 extend into the combustion chamber 107, and the hollow bolts 400 may allow for rotation of the electrodes 110 about the bolt axes (an axis is shown by a dot-dash line in FIG. 4), by turning the bolts 400 or the central conductive rods 408. Third, individual bolts 400 can be replaced by studs extending from one or more inner brackets, with the studs extending through the combustion chamber wall 106 and being capped with nuts to hold the burner assembly 104. If two or more studs were attached to a bracket, it will resist rotation when the studs are inserted through the bolt holes 308 in an object such as the distal flange 206, the burner assembly 104, or the combustion chamber wall 106. These brackets, which hold the studs irrotational against nut-tightening torque, can double as supports for the electrodes 110 or for the sensors 114, the signals from which can also be transferred through the combustion chamber wall 106 by the hollow bolts 400. As the hollow bolts 400 may have cylindrical symmetry, they may be employed as coaxial cables to transmit high-frequency signals from sensors inside the combustion chamber 107.

A fourth embodiment can include a metallic flanged tube through which magnetic fields can propagate. If needed, the tube can include a window. The window can be covered with a sheet of material relatively impervious to air and/or flame but able to pass magnetic fields, or may be open. Such a window will allow the construction of a transformer, with a low-voltage coil on the outside of the adaptor 109 for safety, but with a high-voltage coil on the inside for flame control by the electrodes 110. In this embodiment, the tube itself or the window constitutes an electrical aperture (because the magnetic fields, even if not themselves “electrical”, act to pass electricity).

A fifth embodiment may use the tube 202, between the proximal and the distal flanges 204, 206, as the core of a transformer. An inner high-voltage coil can be grounded at one end and, at the other end, be connected to or include the aperture 118. An outer, low-voltage coil can drive the inner coil. This embodiment may include a grounded metal housing for safety.

FIG. 5 illustrates a sixth embodiment 500 of the electrical aperture 118 (shown in FIGS. 1 and 2), which also uses air as an insulator. A conductive rod 502 passes through the end of a standoff insulator 504 (shown in cross section), which is made of ceramic or other high-temperature electrically insulating material, and which holds the conductive rod 502 in position. Threaded fasteners may take the form of bolts with heads 506 and threads 508, or other fastenings can be used to hold the standoff insulator 504 in position. This embodiment uses air as an insulator, to prolong the electrical discharge path through the solid standoff insulator 504.

In all the embodiments discussed above, the electrical aperture 118 acts to pass through electricity needed for electrodynamic combustion control. Thus the type and thickness of insulation, and the arrangement of the parts, must be such that there is not substantial leakage of electricity to the burner assembly 104 (shown in FIG. 1) or the combustion chamber wall 106 (shown in FIG. 1) (normally, to ground potential). “Substantial” leaking of electricity is defined as the amount of leakage, sparking, or discharge that interferes with electrodynamic combustion control, whether by lowering electrode voltage or current or by interfering with the control mechanisms employed, to an extent that the inventors' object of improving and controlling flames and combustion processes inside the combustion chamber 107 is compromised.

FIG. 6 is a flowchart showing a method 600, according to an embodiment. According to an embodiment, the method 600 includes, in step 602, providing a combustion chamber wall defining a combustion chamber. Step 604 includes providing a burner assembly configured to operatively couple to an exterior of the combustion chamber wall and configured to support a combustion reaction inside the combustion chamber. Step 606 includes providing an adaptor configured to couple between the burner assembly and the combustion chamber wall. The adaptor further may include an adaptor body defining an aperture configured to pass an electrical conductor therethrough. Step 608 includes coupling the burner assembly to the combustion chamber wall via the adaptor.

According to an embodiment, the method 600 further includes passing the electrical conductor through the aperture. In one embodiment, the method 600 further includes providing an electrical bushing, between the adaptor and the electrical conductor, in the aperture. The electrical bushing further may include ceramic.

According to an embodiment, the method 600 further includes providing a power supply disposed outside the combustion chamber and operatively coupled to the electrical conductor, and providing at least one electrode disposed inside the combustion chamber and operatively coupled to the power supply via the electrical conductor. In one embodiment, the method 600 further includes configuring the power supply and the at least one electrode to cooperate to apply electrical energy in proximity to the combustion reaction. In another embodiment, the method 600 further includes configuring the power supply to output a high voltage electrical signal through the electrical conductor to the at least one electrode. Additionally and/or alternatively, the method 600 further includes configuring the power supply to output a high voltage electrical signal greater than about 20 kilovolts through the electrical conductor to the at least one electrode.

According to an embodiment, the method 600 further includes configuring the at least one electrode to apply an electrical field near the combustion reaction. In another embodiment, the method 600 further includes configuring the at least one electrode to output charged particles to the combustion reaction. Additionally and/or alternatively, the method 600 further includes configuring the at least one electrode to not form an electrical spark.

According to an embodiment, the method 600 further includes configuring the power supply and the at least one electrode to generate a plasma within the combustion chamber. In one embodiment, the plasma is a low temperature plasma. The low temperature plasma may have a temperature too low to ignite a fuel and oxidant mixture. Additionally and/or alternatively, the low temperature plasma may have sufficient energy to maintain an ignition of the fuel and oxidant mixture. In another embodiment, the plasma is a high temperature plasma. The high temperature plasma may have a temperature sufficient to ignite the fuel and oxidant mixture.

According to an embodiment, the power source includes a pulsed power source. In one embodiment, the pulsed power source is operable to output nanosecond electrical pulses having a duration of between 100 picoseconds and 300 nanoseconds. In another embodiment, the pulsed power source is operable to output at least 10 kilovolt nanosecond electrical pulses. Additionally and/or alternatively, the pulsed power source is operable to output about 30 kilovolt nanosecond electrical pulses. In an embodiment, the pulsed power source is operable to output nanosecond electrical pulses at a duty cycle of between 1 and 50%. In another embodiment, the pulsed power source is operable to output pulses at a rate of 10 kilohertz to 100 kilohertz.

According to an embodiment, the at least one electrode is a corona electrode. In another embodiment, the at least one electrode is a dielectric barrier discharge electrode.

According to an embodiment, the burner assembly includes a flange configured to couple to the combustion chamber wall, and the adaptor includes a proximal coupling surface configured to couple to the burner assembly flange, an adaptor wall projecting away from the proximal coupling surface, and a distal coupling surface coupled to a distal end of the adaptor wall and configured to couple to the combustion chamber wall. In one embodiment, the adaptor further includes a proximal adaptor flange on which the proximal coupling surface is formed. The adaptor may further include a distal adaptor flange on which the distal coupling surface is formed, The adaptor wall may extend from the proximal adaptor flange to the distal adaptor flange. In another embodiment, the aperture is formed in the adaptor wall. Additionally and/or alternatively, the aperture defined by the adaptor body has a shape configured to receive an electrical bushing. In one embodiment, the aperture defined by the adaptor body is threaded.

According to an embodiment, the method 600 further includes fastening, with fasteners, the adaptor to the burner assembly and to the combustion chamber wall.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

1. A method, comprising:

providing a combustion chamber wall defining a combustion chamber;

providing a burner assembly configured to operatively couple to an exterior of the combustion chamber wall and configured to support a combustion reaction inside the combustion chamber;

providing an adaptor configured to couple between the burner assembly and the combustion chamber wall, wherein the adaptor further comprises an adaptor body defining an aperture configured to pass an electrical conductor therethrough; and

coupling the burner assembly to the combustion chamber wall via the adaptor.

2. The method of claim 1, further comprising:

passing the electrical conductor through the aperture.

3. The method of claim 2, further comprising:

providing an electrical bushing, between the adaptor and the electrical conductor, in the aperture.

4. The method of claim 3, wherein the electrical bushing further comprises ceramic.

5. The method of claim 1, further comprising:

providing a power supply disposed outside the combustion chamber and operatively coupled to the electrical conductor; and

providing at least one electrode disposed inside the combustion chamber and operatively coupled to the power supply via the electrical conductor.

6. The method of claim 5, further comprising:

configuring the power supply and the at least one electrode to cooperate to apply electrical energy in proximity to the combustion reaction.

7. The method of claim 5, further comprising:

configuring the power supply to output a high voltage electrical signal through the electrical conductor to the at least one electrode.

8. The method of claim 5, further comprising:

configuring the power supply to output a high voltage electrical signal greater than about 20 kilovolts through the electrical conductor to the at least one electrode.

9. The method of claim 5, further comprising:

configuring the at least one electrode to apply an electrical field near the combustion reaction.

10. The method of claim 5, further comprising:

configuring the at least one electrode to output charged particles to the combustion reaction.

11. The method of claim 5, further comprising:

configuring the at least one electrode to not form an electrical spark.

12. The method of claim 5, further comprising:

configuring the power supply and the at least one electrode to generate a plasma within the combustion chamber.

13. The method of claim 12, wherein the plasma is a low temperature plasma.

14. The method of claim 13, wherein the low temperature plasma has a temperature too low to ignite a fuel and oxidant mixture.

15. The method of claim 14, wherein the low temperature plasma has sufficient energy to maintain an ignition of the fuel and oxidant mixture.

16. The method of claim 12, wherein the plasma is a high temperature plasma.

17. The method of claim 16, wherein the high temperature plasma has a temperature sufficient to ignite the fuel and oxidant mixture.

18. The method of claim 5, wherein the power source comprises a pulsed power source.

19. The method of claim 18, wherein the pulsed power source is operable to output nanosecond electrical pulses having a duration of between 100 picoseconds and 300 nanoseconds.

20. The method of claim 18, wherein the pulsed power source is operable to output at least 10 kilovolt nanosecond electrical pulses.

21. The method of claim 20, wherein the pulsed power source is operable to output about 30 kilovolt nanosecond electrical pulses.

22. The method of claim 18, wherein the pulsed power source is operable to output nanosecond electrical pulses at a duty cycle of between 1% and 50%.

23. The method of claim 18, wherein the pulsed power source is operable to output pulses at a rate of 10 kilohertz to 100 kilohertz.

24. The method of claim 12, wherein the at least one electrode is a corona electrode.

25. The method of claim 12, wherein the at least one electrode is a dielectric barrier discharge electrode.

26. The method of claim 1, wherein the burner assembly includes a flange configured to couple to the combustion chamber wall; and

wherein the adaptor comprises:

a proximal coupling surface configured to couple to the burner assembly flange;

an adaptor wall projecting away from the proximal coupling surface; and

a distal coupling surface coupled to a distal end of the adaptor wall and configured to couple to the combustion chamber wall.

27. The method of claim 26, wherein the adaptor further comprises a proximal adaptor flange on which the proximal coupling surface is formed;

wherein the adaptor further comprises a distal adaptor flange on which the distal coupling surface is formed; and

wherein the adaptor wall extends from the proximal adaptor flange to the distal adaptor flange.

28. The method of claim 26, wherein the aperture is formed in the adaptor wall.

29. The method of claim 1, wherein the aperture defined by the adaptor body has a shape configured to receive an electrical bushing.

30. The method of claim 29, wherein the aperture defined by the adaptor body is threaded.

31. The method of claim 1, further comprising fastening, with fasteners, the adaptor to the burner assembly and to the combustion chamber wall.