Adaptor for providing electrical combustion control to a burner

Abstract

Technologies are provided for 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.

Claims

1. A combustion system, comprising: a combustion chamber wall defining a combustion chamber; 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 accessory mounted between the burner assembly and the combustion chamber wall; and at least one fastener configured to fasten the adaptor accessory to the burner assembly and to the combustion chamber wall; wherein the adaptor accessory includes an adaptor body defining an aperture configured to pass an electrical conductor therethrough; and wherein the electrical conductor is configured to carry a voltage electrical signal from outside the combustion chamber wall to inside the combustion chamber through the adaptor body aperture; whereby the adaptor accessory retrofits the combustion system.

2. The combustion system of claim 1, wherein the aperture is configured to receive an electrical bushing; and wherein the electrical bushing is configured to carry the electrical conductor.

3. The combustion system of claim 2, wherein the electrical bushing further comprises a ceramic electrical insulator.

4. The combustion system of claim 1, further comprising: a power supply disposed outside the combustion chamber and operatively coupled to the electrical conductor; and at least one electrode disposed inside the combustion chamber and operatively coupled to the power supply via the electrical conductor.

5. The combustion system of claim 4, wherein the power supply and the at least one electrode are configured to cooperate to apply electrical energy in proximity to the combustion reaction.

6. The combustion system of claim 4, wherein the power supply is configured to output a high voltage electrical signal through the electrical conductor to the at least one electrode.

7. The combustion system of claim 6, wherein the power supply is configured to output a high voltage electrical signal greater than about 20 kilovolts through the electrical conductor to the at least one electrode.

8. The combustion system of claim 4, wherein the electrode is configured to apply an electrical field near the combustion reaction.

9. The combustion system of claim 4, wherein the electrode is configured to output charged particles to the combustion reaction.

10. The combustion system of claim 4, wherein the electrode is configured to not form an electrical spark.

11. The combustion system of claim 1, wherein the burner assembly comprises a burner assembly flange configured to couple to the combustion chamber wall; and wherein the adaptor accessory 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.

12. The combustion system of claim 11, wherein the adaptor accessory includes a proximal adaptor flange on which the proximal coupling surface is formed; wherein the adaptor accessory includes 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.

13. The combustion system of claim 11, wherein the aperture is formed in the adaptor wall.

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

15. The combustion system of claim 14, wherein the aperture defined by the adaptor body is threaded.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) 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.

(3) 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.

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

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

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

DETAILED DESCRIPTION

(7) 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.

(8) 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. The 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.

(9) 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.

(10) 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; Ser. No. 14/144,431, entitled WIRELESSLY POWERED ELECTRODYNAMIC COMBUSTION SYSTEM, filed Dec. 30, 2013; and Ser. No. 14/179,375, entitled METHOD AND APPARATUS FOR DELIVERING A HIGH VOLTAGE TO A FLAME-COUPLED ELECTRODE, filed Feb. 12, 2014; the contents of which are each incorporated herein by reference.

(11) 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.

(12) 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.

(13) In an embodiment, the adaptor 109 is configured to couple between the burner assembly 104 and the combustion chamber wall 106. The adaptor 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.

(14) The aperture can be configured to receive an electrical bushing 214 configured to carry the electrical conductor.

(15) 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 the 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.

(16) 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, computer, and may adjust the voltage of the power supply 112 according to timing, flame feedback, predetermined criteria, etc. If a processor or 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.

(17) 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.

(18) 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.

(19) 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.

(20) FIG. 2 shows an embodiment 200 of the adaptor 109, 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).

(21) 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 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 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.

(22) 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.

(23) 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 air flow can 208 that will allow the 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 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 air flow can 208 when the air flow can 208 is in place (for systems that include 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 air flow can 208, and cases of the electrode 110 remaining outside the air flow can 208.

(24) 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.

(25) It is known in the art that the air flow can 208 may separate primary from secondary combustion air. Consequently, no matter where the electrode 110 is (inside or outside the 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 primarily air flow can 208, while the region in between the 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 air-flow 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.

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

(27) 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 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 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.

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

(29) 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 distal flanges 204, 206).

(30) FIGS. 3A and 3B show an embodiment 300, 301 of the adaptor 109 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.

(31) 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 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.

(32) 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 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.

(33) In an embodiment, the applicants contemplate applying high voltages of up to or beyond about 20 kV. In another embodiment, the applicants 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.

(34) While only one metal portion 310 is illustrated in FIG. 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.

(35) 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 wire or rod 408 can connect on the outside to the power supply 112 of the electrodynamic combustion system 104, 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 combustion device.

(36) This embodiment has several advantages. First, the burner assembly offset as compared to that without is negligible. Second, the electrode 110 can be fastened directly to the inner threaded end of the central 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 central 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 bolt holes 308 in an object such as the distal flange 206, burner assembly 104, or 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 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.

(37) 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).

(38) A fifth embodiment may use the tube 202, between the proximal and 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.

(39) 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 fastening can be used to hold the standoff 118 in position. This embodiment uses air as an insulator, to prolong the electrical discharge path through the solid standoff insulator 504.

(40) 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 applicants' object of improving and controlling flames and combustion processes inside the combustion chamber 107 is compromised.

(41) 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.