Patent Application
20140212820
There are a wide variety of burners available that are used in a wide variety of applications. The operation of burner systems raises many concerns. Undesirable outputs (e.g., NOx), excessive fuel consumption, and heat output are examples of these concerns.
As a result, many attempts have been made to address these concerns. These attempts include fuel composition, diluents, premixing, or the like. By changing or including structure that are directed to these aspects of burner technology, the operation and efficiencies of burner systems has improved over time.
However, there is still a need for burner systems and methods having improved operation and efficiency.
Embodiments of the invention are directed to a burner system including at least one Coanda surface and at least two electrodes that are biased in a manner to influence a location of fuel flow and/or a flame relative to the at least one Coanda surface (e.g., directing the fuel flow toward or away from the at least one Coanda surface), and related methods. In an embodiment, a burner system includes at least one Coanda surface, at least one nozzle positioned and configured to emit a fuel flow at least proximate to the at least one Coanda surface, at least two electrodes, and a voltage source operably coupled to the at least two electrodes. The voltage source may be configured to bias the at least two electrodes to generate an electric field at least proximate to the at least one Coanda surface that influences a location of the fuel flow and/or the flame relative to the at least one Coanda surface.
In an embodiment, a method of operating a burner system is disclosed. The method includes directing a charged fuel flow from at least one nozzle toward at least one Coanda surface. The method additionally includes biasing at least two electrodes to generate an electric field at least proximate to the at least one Coanda surface. The method further includes at least partially based on the electric field, influencing a location of the charged fuel flow and/or the flame relative to the at least one Coanda surface.
Features from any of the disclosed embodiments may be used in combination with one another, without limitation. In addition, other features and advantages of the present disclosure will become apparent to those of ordinary skill in the art through consideration of the following detailed description and the accompanying drawings.
Embodiments of the invention are directed to a burner system including at least one Coanda surface and at least two electrodes that are biased in a manner to influence a location of fuel flow relative to the at least one Coanda surface (e.g., directing the fuel flow toward or away from the at least one Coanda surface), and related methods. More specifically, embodiments disclosed herein relate to burner systems and methods for controlling characteristics of flames and/or fuel in burner systems, such as controlling stoichiometry of the fuel, shape of the flame, location of the fuel flow and/or flame relative to the at least one Coanda surface, or any combination thereof For example, by biasing the at least two electrodes so that the fuel flow or the flame is attracted and/or better conforms to the at least one Coanda surface, heat may be more effectively extracted from the fuel flow and/or the flame so that the combustion temperature is lowered, thereby reducing pollutants (e.g., NOx).
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.
Coanda surfaces are surfaces that are configured for producing fluid flow exhibiting the Coanda effect. The Coanda effect relates to the tendency of a fluid to follow a surface. When properly configured, the fluid will follow, or “hug” or generally conform to a Coanda surface even as the surface curves away from the initial fluid flow direction. In the context of burners and by way of example only, a Coanda surface may be used to aid in mixing fuel with air and/or a diluent. By placing a Coanda surface in the flow path of a fuel stream, the fuel may be more effectively mixed with air and/or diluent over the Coanda surface, heat from the flame may be conductive to the Coanda surface to lower the flame temperature, or combinations thereof. This may result in reduced pollutants (e.g., NOx) and other efficiencies. A flame may also follow a Coanda surface. While a Coanda surface may be used to control the stoichiometry and/or the geometry of a flame to some extent, any of the electrodynamic electrode control systems disclosed herein provide greater control over the stoichiometry of the fuel and/or flame, geometry of the flame, charge density of the flame, location of the fuel flow and/or flame relative to the Coanda surface, or combinations thereof.
The burner system 100 further includes a charger 110 that is configured to inject charge into the fuel and/or the flame area 104. By injecting charge with the charger 110, the fuel, flame area, flame, or combinations thereof acquires a net electrical charge (e.g., a net positive or negative charge). In an embodiment, the charger 110 may include a corona electrode (e.g., a sharpened electrode or saw blade) configured to generate ions that are injected into the fuel, flame area, flame, or combinations thereof to impart the net electrical charge.
As a result of this net electrical charge generated by the charger 110 in the flame area 104, electrode(s) 108 may affect certain characteristics of the fuel, the flame area, the flame, or combinations thereof. In an embodiment, at least one of the electrode(s) 108 may be incorporated with one or more Coanda surfaces that have placed thereon an electrical conductor or an electrically conductive structure to form one or more Coanda electrodes. In another embodiment, the electrode(s) 108 may include two or more electrodes that are spaced from and separate from the Coanda surface(s).
The electrodes of the electrode(s) 108 (including Coanda electrodes, counter electrodes, and corona electrodes) may be placed in various locations relative to the flame area 104. For example, a corona electrode may be placed below the flame area 104 and below the Coanda surface(s) such that the corona electrode may inject charge into the fuel flow, while in other embodiments, the corona electrode may be positioned to inject charge into the flame itself. The electrodes may then shape and/or influence one or more of the fuel flow, the burning fuel, or the flame using the Coanda effect as well as the interaction between the potential of the electrodes and the charged fuel and/or flame. For example, the electrodes may be biased to attract or repel the charged fuel and/or flame in a desired manner while still exhibiting the Coanda effect.
The burner system 100 further includes a controller 112 that may include one or more processors or other special purpose computers and associated components. The controller 112 may be configured to control an amount of charge injected by the charger 110, the potential and/or polarity of the various electrodes in the burner system 100, a fuel flow rate, fuel pressure, mixing ratios, or any combination thereof. The control system 112 may be further operably coupled to a voltage source 114 operably coupled to the electrode(s) 108 and/or the charger 110 for applying a voltage thereto. For example, the electrodes proximate to the Coanda surface(s) may be biased to generate an electric field that attracts or repels the charged fuel and/or flame in a desired manner.
The at least two electrodes 208a and 208b are spaced and positioned relative to the at least one Coanda surface 204 so that an electric field generated therebetween by application of a voltage therebetween by the voltage source 210 influences a location of the fuel and/or flame relative to the at least one Coanda surface 204. For example, if the fuel and/or flame is charged positively or negatively, a potential having an opposite polarity as the charge of the fuel and/or flame between the at least two electrodes 208a and 208b causes the charged fuel and/or flame to be attracted to the at least one Coanda surface 204 and further conform to the curvature of the at least one Coanda surface 204 and/or better maintain conformity between the charged fuel and/or flame and the at least one Coanda surface 204. As another example, if the fuel and/or flame is charged positively or negatively, a potential of the same polarity as the charge of the fuel and/or flame between the at least two electrodes 208a and 208b causes the charged fuel and/or flame to be repelled from the at least one Coanda surface 204 which may be desired in certain combustion applications.
The voltage applied to the electrodes 208a and 208b (and/or to other electrodes in a burner system 200) to generate the electric field therebetween may be DC, AC, invertible, chopped, or have another signal shape. In some embodiments, currents may be in a milliamp range (e.g., 100 milliamp range), while the voltages may be in a kilovolt range. Other ranges, higher and lower currents/voltages may be used or applied to the electrodes 208a and 208b and/or to other electrodes in the burner system 200.
When the fuel and/or mixed fuel exits the nozzles 304 and 306 and enters a flame area 322, the fuel and/or the mixed fuel encounters a Coanda member 312 (e.g., a Coanda tile) that includes an outer Coanda surface 326 and an inner Coanda surface 328. In an embodiment, the Coanda member 312 may be a substantially continuous annular body, while in other embodiments the Coanda member 312 may be discontinuous, such as an interrupted annular body. The fuel and/or combusting fuel in the flame area 322 may burn more efficiently due to the Coanda surfaces 326 and 328. For example, the Coanda surfaces 326 and 328 may improve the stoichiometry of the fuel by allowing the fuel to mix better with air and/or a diluent as the fuel flows over the Coanda surfaces 326 and 328. As a result, the burning and combustion is more efficient since the fuel mixing becomes more efficient.
In the illustrated embodiment, both of the Coanda surface 326 and the Coanda surface 328 may be configured as electrodes as well. Thus, the Coanda surfaces 326 and 328 function as Coanda electrodes 318a and 320a by at least partially covering the Coanda surfaces 326 and 328 with an electrical conductor of some configuration or forming the Coanda bodies 312 and 314 from an electrically conductive material, such as a metal or alloy (e.g., a refractory metal or alloy). In an embodiment, the Coanda electrodes 318a and 320a may be formed by stamping a steel or other metallic plate onto the surface or by plating the Coanda surfaces 326 and 328 with an electrically conductive material, such as a suitable metallic material. In an embodiment, the Coanda electrodes 318a and 320a may be electrically conductive traces (which may or may not touch) that may have a common voltage source or that may be remotely connected or that may be controlled independently. Corresponding counter electrodes 318b and 320b are provided that are spaced from corresponding Coanda electrodes 318a and 320a. For example, the counter electrodes 318b and 320b may each be electrically conductive rings, a plurality of circumferentially-spaced electrodes, or other suitable geometry. It should be noted that the electrodes in the burner system 300 may be arranged in multiple other configurations. For example, in other embodiments, separate electrodes may be provided that are separate from and spaced from the respective Coanda surfaces 326 and 328 similar to the burner system 200 shown in
The burner system 300 further includes a charger having a corona electrode 316 that is located, in the illustrated embodiment, near a base or bottom portion of the Coanda surfaces 326 and 328. For example, the corona electrode 316 may be configured as a ring having serrated or other sharp features from which charges are emitted into the fuel flow output by the nozzles 304 and 306. However, in other embodiments, the charger may be placed in other locations so that the fuel from a fuel source (not shown) may be charged prior to being output by the nozzles 304 and 306 and/or the flame itself may be charged. By placing the corona electrode 316 (or other type of charger) in a position (e.g., the path of the fuel between the nozzles and the Coanda electrodes 318 and 320) to generate ions that may be added to or injected in the fuel, the fuel or the flame area may be charged. By charging or ionizing the fuel and/or the combusting fuel at a given location, the Coanda electrodes 318a and 320a may also act on the charged fuel, the combusting fuel, the charged flame, or combinations thereof
The burner system 300 further includes a voltage source 324, under control of a controller 326, operably coupled to the Coanda electrodes 318a and 320a, and corresponding counter electrodes 318b and 320b, and the corona electrode 316. In operation, a voltage applied to the Coanda electrodes 318a and 320a and corresponding counter electrodes 318b and 320b generates corresponding electric fields proximate to or adjacent to the corresponding Coanda electrodes 318a and 318b. The voltage source 324 under control of the controller 326 also applies a suitable voltage to the corona electrode 316 to cause charges to be emitted into the fuel flow from the nozzles 304 and 306.
By application of a suitable voltage via the voltage source 324 to the Coanda electrodes 318a and 320b and corresponding counter electrodes 318b and 320b to generate corresponding electric fields proximate to or adjacent to the Coanda electrodes 318a and 318b, the fuel and/or flame having injected charges may be repelled from or attracted to the Coanda electrodes 318a/318b and Coanda surfaces 326/328 such that burning occurs away from or closer to the surface of the Coanda surfaces 326 and 328. For example, when the fuel and/or flame is attracted to the Coanda electrodes 318a/318b and Coanda surfaces 326/328, heat from the flame may be conducted to the Coanda surfaces 326/328 to lower the flame temperature, which may result in reduced pollutants (e.g., NOx) and other efficiencies. If not electrically connected together, the Coanda electrode 318a may be controlled differently (e.g., different potential and/or charge) from the Coanda electrode 320a.
In some embodiments, the Coanda electrodes 318a and 320a may be used to control some aspects of the flame and/or fuel and other electrodes (not shown) may be configured to control other aspects of the flame and/or fuel. For example, the Coanda electrodes 318a and 320a may at least partially control the mixing and location of the fuel and/or flame relative to the Coanda surfaces 326 and 328, while other electrodes may similarly act on the biased flame to control a geometry of the flame such as the flame height. In such an embodiment, one or more electrodes may be arranged above the flame that are biased to effectively repel the flame downward to control flame height. In such an embodiment, each of the electrodes may be connected to the same voltage or electrical source. Alternatively, some of the electrodes may be electrically isolated from other electrodes. For example, the Coanda electrodes 318a and 320a and/or the corona electrode 316 may be controlled independently due, for example, to differing voltage requirements.
In another embodiment, the Coanda electrodes 318a and 320a and other electrodes may be configured to operate as discussed herein without injecting charge with the corona electrode 316. In other words, the fuel and/or flame already includes some ions or charged particles and the electrodes may operate on the fuel/flame without requiring the injection of charge. Thus, in any of the embodiments disclosed herein, the charger (e.g., a corona electrode) may be omitted.
In operation, the plurality of electrodes 404a-404e may be independently biased to selectively generate an electrical field between, for example, two adjacent ones of the plurality of electrodes 404a-404e. For example, the voltage source 408 may apply a voltage to the electrodes 404a and 404b to generate an electric field therebetween that promotes sweeping positive charged species from fuel flow 412 output from the nozzle 202 and/or flame along the Coanda surface 402. In a selected time after application of the voltage to the electrodes 404a and 404b, the voltage source 408 may apply a voltage to the electrodes 404b and 404c to generate another electric field therebetween that promotes further sweeping positive charged species the fuel flow 412 and/or flame along the Coanda surface 402. The sequential biasing of adjacent pairs of the plurality of electrodes 404a-404e may be sequentially continued until a voltage is applied to the electrodes 404d and 404ec to generate another electric field therebetween that promotes further sweeping positive charged species along the Coanda surface 402, after which the sequential biasing process may be repeated a selected number of times or repeated continually. This sequential biasing of adjacent ones of the plurality of electrodes 404a-404e may help the fuel flow 412 and/or flame further conform to the curvature of the Coanda surface 402 and/or better maintain conformity between the charged fuel and/or flame and the Coanda surface 402.
It should be noted that the number of the plurality of electrodes 404a-404e illustrated in
The operation of the electrodes, charger, and fuel source of any of the embodiments disclosed herein may be controlled by a controller or computer system and embodiments of the invention may include a special purpose or general-purpose computer including various computer hardware or other hardware including duplexers, amplifiers, or the like, as discussed in greater detail below for controlling the operation of the electrodes, charger, and fuel source.
Embodiments of the invention also include computer-readable media for carrying or having computer-executable instructions or data structures stored thereon for executing any of the methods disclosed herein such as the method 400 or other instructions for directing the operation of any of the burner systems disclosed herein. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. Combinations of the above should also be included within the scope of computer-readable media.
Computer-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
This application claims priority to U.S. Provisional Application No. 61/758,362 filed on 30 Jan. 2013, the disclosure of which is incorporated herein, in its entirety, by this reference.
| Number | Date | Country | |
|---|---|---|---|
| 61758362 | Jan 2013 | US |
