COMBUSTION SYSTEMS AND METHODS FOR REDUCING COMBUSTION TEMPERATURE

Abstract

Embodiments disclosed herein are directed to combustion systems that include a mechanism or device for reducing combustion temperature. For example, in an embodiment, a combustion system may include a flame control assembly that may draw combusted fuel (e.g., flame produced during combustion) toward a structure that may absorb heat therefrom, thereby reducing combustion temperature.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 62/015,683 filed on 23 Jun. 2014, the disclosure of which is incorporated herein, in its entirety, by this reference.

BACKGROUND

In some instances, reducing the combustion temperature may be desirable. For instance, combustion that occurs at a reduced temperature may produce less oxides of nitrogen (NOx) than the same or similar combustion at a higher temperature (e.g., as compared with the combustion temperature of a fuel without approaches for controlling combustion temperature).

Generally, NOx is considered to be an air pollutant. For instance, NOx may react to form ozone. As such, it may be preferable to reduce NOx production by devices and systems that combust fuel.

Accordingly, users and manufacturers of devices and systems that combust fuel continue to seek improvements to reduce NOx production by such devices.

SUMMARY

Embodiments disclosed herein are directed to combustion systems that include a mechanism or device for reducing combustion temperature. For example, a combustion system may include a combustion control assembly. In some embodiments, the combustion control assembly may include a combustion controller that may control the device for reducing combustion temperature. In some instances, the combustion controller and the device for reducing combustion temperature may cooperate in a manner that attracts combusted fuel (e.g., flame produced during combustion) toward one or more structures that may absorb heat therefrom, thereby reducing combustion temperature of the flame.

One or more embodiments include a combustion system that has a combustion chamber including at least one chamber wall and a source of combustible fuel for producing a flame in the combustion chamber. The combustion system includes a flame control electrode assembly mounted to the at least one chamber wall. More specifically, the flame control electrode assembly including a plurality of flame control electrodes. The flame control electrode assembly is configured to produce an electric field that attracts the flame toward the chamber wall.

Embodiments are also directed to a method of reducing NOx produced during combustion in a combustion chamber. The method includes combusting a fuel inside of the combustion chamber to produce a flame having a net positive charge or net negative charge. The method further includes producing an electric field having a charge opposite to the flame charge. The electric field is positioned near at least one chamber wall of the combustion chamber. In addition, the method includes attracting the flame toward the at least one chamber wall and transferring heat from the flame to the at least one chamber wall to thereby reduce a combustion temperature of the flame.

Embodiments also include a combustion system that includes a combustion chamber including at least one chamber wall, a source of combustible fuel for producing a flame in the combustion chamber, and at least one ionizer. The ionizer is positioned and configured to ionize the fuel and/or the produced flame. The combustion system also includes a flame control electrode assembly mounted to the at least one chamber wall. The flame control electrode assembly includes a plurality of flame control electrodes that are electrically insulated from each other. The flame control electrode assembly is configured to produce an electric field that attracts the flame toward the at least one chamber wall. Moreover, the combustion system includes a controller electrically coupled to the flame control electrode assembly. The controller is configured to regulate the electric field produced by the flame control electrode assembly.

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.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate several embodiments, wherein identical reference numerals refer to identical or similar elements or features in different views or embodiments shown in the drawings.

FIG. 1A is a cutaway plan view of a combustion system according to an embodiment of the invention;

FIG. 1B is a cutaway plan view of the combustion system of FIG. 1A during operation thereof according to an embodiment of the invention;

FIG. 1C is a cutaway partial isometric view of the combustion system of FIG. 1A operating without an activated flame control electrode assembly;

FIG. 1D is a cutaway partial isometric view of the combustion system of FIG. 1A operating with an activated flame control electrode assembly according to an embodiment of the invention;

FIG. 2 is a partial isometric cutaway view of a flame control electrode assembly mounted on a wall of a combustion chamber according to an embodiment of the invention;

FIG. 3 is a cross-sectional view of a flame control electrode assembly mounted on a wall of a combustion chamber according to an embodiment of the invention;

FIG. 4 is a cross-sectional view of a flame control electrode assembly mounted on a wall of a combustion chamber according to another embodiment of the invention;

FIG. 5 is a cross-sectional view of a flame control electrode assembly mounted on a wall of a combustion chamber according to yet another embodiment of the invention;

FIG. 6 is a cross-sectional view of a flame control electrode assembly mounted on a wall of a combustion chamber according to still another embodiment of the invention;

FIG. 7 is a cross-sectional view of a flame control electrode assembly mounted on a wall of a combustion chamber according to an additional or alternative embodiment of the invention; and

FIG. 8 is a flow diagram of a method for reducing NOx during combustion of a fuel according to an embodiment of the invention.

DETAILED DESCRIPTION

Embodiments disclosed herein are directed to combustion systems that include a mechanism or device for reducing combustion temperature. For example, a combustion system may include a combustion control assembly that may reduce temperature of combusted fuel (e.g., reduce flame temperature). The combustion control assembly, in some embodiments, may include a combustion controller that may control the device for reducing combustion temperature. In some instances, the combustion controller and the device for reducing combustion temperature may cooperate in a manner that draws or attracts combusted fuel (e.g., flame produced during combustion) toward one or more structures that may absorb heat therefrom, thereby reducing combustion temperature.

In some embodiments, the device for reducing combustion temperature may include one or more flame control electrode assemblies that may be controlled and/or powered by the combustion controller. 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. 1A illustrates a combustion system 100 that may be deployed for any number of suitable objectives or uses, including but not limited to heating. For example, the combustion system 100 may include one or more sources of fuel and oxidizer, which may be combusted inside the combustion chamber. The oxidizer may be supplied in the form of combustion air carrying oxygen. Specifically, in an embodiment, the combustion system 100 may include a fuel line 110 that may supply combustible fuel into a combustion chamber 120. In some embodiments, inside the combustion chamber 120, the fuel line 110 may terminate with a nozzle that may have suitable configuration for injecting the fuel into the combustion chamber 120. Among other factors, the particular configuration of the fuel nozzle may be selected based on at least one of the type of fuel, size of the fuel line, fuel pressure, configuration of the combustion chamber 120, etc. In any event, the fuel nozzle may facilitate spraying or otherwise injecting the fuel into the combustion chamber 120.

In some examples, the fuel line 110 may provide a premixed fuel that may include an oxidizer such as air mixed with the fuel. For example, the fuel line 110 may inject a fuel-air mixture into the chamber, which may be ignited or combusted inside the combustion chamber 120. In alternative or additional embodiments, the combustion system 100 may include a separate oxidizer line 130, which may supply an oxidizer that may be mixed with the fuel supplied by the fuel line 110. For instance, the oxidizer (e.g., air) supplied by the oxidizer line 130 may be mixed with the fuel inside the combustion chamber 120, after the fuel is provided into the combustion chamber 120. Alternatively, however, the oxidizer from the oxidizer line 130 may be mixed with the fuel from the fuel line 110 at another location (e.g., outside of the combustion chamber 120) and supplied into the combustion chamber by another line. Moreover, in some embodiments, the combustion chamber 120 may include an oxidizer that may facilitate ignition and/or combustion of the fuel. In any case, the fuel supplied into the combustion chamber 120 may be combusted therein.

In an embodiment, the combustion system 100 also may include an exhaust or flue 140 that may facilitate removal of combusted gases that may be produced during combustion. For example, the flue 140 may be positioned distally from the fuel line 110 and/or from the nozzle (e.g., in the direction of flow of the fuel), such that products formed during and/or after combustion of the fuel may exit the combustion chamber 120 through the flue 140. In some embodiments, the flue 140 may be a passive exhaust, which may allow exhaust gases to exit the combustion chamber 120. Alternatively, the flue 140 may produce a negative pressure (at least near the opening thereof in the combustion chamber 120), which may actively draw the flame and/or exhaust gases produced during combustion into the flue 140 and out of the combustion chamber 120.

In some embodiments, the combustion system 100 may include an igniter that may ignite the fuel and oxidizer mixture inside the combustion chamber 120. It should be appreciated that any suitable igniter (e.g., a spark igniter) may be included in the combustion system 100, and the specific igniter may vary from one embodiment to the next. Furthermore, in some instances, elevated temperature inside the combustion chamber 120 may produce ignition and/or sustain ignition and combustion of the fuel mixture.

Generally, the combustion chamber 120 of the combustion system 100 may have any suitable size, shape, configuration, or combinations thereof. In the illustrated embodiment, the combustion chamber 120 has an approximately rectangular shape defined by surrounding walls, such as chamber walls 150. The chamber walls 150 may include any number of suitable materials and/or components that may include refractory or otherwise heat-resistant materials (e.g., refractory blocks or fire brick), which may withstand the temperatures produced inside the combustion chamber 120.

In some embodiments, the combustion system 100 may include a single fuel line 110. Alternatively, the combustion system 100 may include multiple fuel lines 110 (a centerline 10 provides an imaginary line of symmetry of the combustion chamber 120 and/or other components thereof). Hence, in some embodiments, the combustion system 100 may include multiple fuel lines that may be similar to or the same as the fuel line 110, and which may be located on opposing sides of the combustion chamber 120. Furthermore, embodiments may include combustion chambers that may have approximately cylindrical, spherical, elliptical, or any other shape that may be suitable for a particular application of the combustion system, for a particular fuel, and the like.

As mentioned above, in some embodiments, the combustion system 100 may be a heater. For instance, the combustion system 100 may include one or more heat exchangers 160 located inside the combustion chamber 120. At least a portion of the heat produced in the combustion chamber 120 (from combusting the fuel) may be transferred to the heat exchanger 160. More specifically, in some embodiments, the heat exchanger 160 may circulate fluid therethrough, and the fluid in the heat exchanger 160 may be heated as the fluid passes through the heat exchanger 160. For example, the heat exchanger 160 may be convectively heated inside the combustion chamber 120 and may transfer heat to the fluid circulating therethrough.

The heated fluid may be used to heat objects, substances, locations, or combinations thereof. Additionally or alternatively, in some embodiments, the combustion system 100 may be in direct contact with one or more objects or substances intended for heating and may transfer heat directly to such objects or substances (i.e., without a heat exchanger). In any case, the combustion system 100 may transfer at least a portion of the heat from the combustion chamber 120 to an intended or target object or substance.

The combustion system 100 further includes a device for reducing temperature of combustion, such as a flame control electrode assembly 170, which is described below in further detail. In an embodiment, the flame control electrode assembly 170 may be attached to and/or mounted on one or more of the chamber walls 150. For example, the flame control electrode assembly 170 may be located on the chamber walls 150 and may be positioned distally from the outlet or nozzle of the fuel line 110. In one or more embodiments, the flame control electrode assembly 170 may be positioned between the outlet or nozzle of the fuel line 110 and the flue 140.

In one or more embodiments, in operation, the flame control electrode assembly 170 may attract the combusted fuel and oxidizer mixture (e.g., the flame produce during combustion) as such combusted mixture extends and/or moves away from the outlet of the fuel line 110. Moreover, the flame control electrode assembly 170 may transfer at least some heat from the combusted fuel to the chamber walls 150, thereby reducing a combustion temperature of the flame. As noted above, in some instances, reducing the temperature of the combusted fuel or flame may reduce NOx produced thereby. Accordingly, the transferring heat from combusted fuel in the combustion chamber 120 to the flame control electrode assembly 170 and/or to the chamber walls 150, may reduce NOx produced by the combustion system 100.

In an embodiment, the fuel and/or oxidizer combusted in the combustion chamber 120 may be ionized. For example, the combustion system 100 may include one or more ionizers, such as ionizers 180a, 180b that may inject ions (i.e., electrically charged molecules) into the fuel and/or oxidizer, respectively, or may otherwise ionize the fuel and/or oxidizer. In some embodiments, ions may be injected into the oxidizer by arc discharge between a cathode and anode. Moreover, in some instances, an ionizer may inject ions directly into the flame (i.e., after ignition of the fuel). For example, the ionizers 180a, 180b may be corona electrodes, such as a sharpened metallic electrode or a piece of a metallic saw blade.

The combustion system 100 further includes a combustion controller 190 electrically coupled to the ionizers 180a and/or 180b. In some embodiments, the combustion controller 190 may regulate the flow of fuel and/or oxidizer into the combustion chamber 120. The combustion controller 190 may also control the ionizers 180a and/or 180b and the flow of oxidizer and fuel in a manner that introduces a fuel mixture of a desired or suitable ionization (i.e., a mixture that has a suitable net positive or net negative charge) into the combustion chamber 120.

As shown in FIG. 1B, the flame control electrode assembly 170 may attract the ionized fuel and oxidizer before combustion, during combustion, after combustion, or combinations thereof. For instance, FIG. 1B illustrates fuel and oxidizer mixture combusted to form a flame 20, which may be attracted to the flame control electrode assembly 170, as the flame 20 advances from the fuel line 110 toward the flue 140. In some embodiments, the combustion controller 190 also may be electrically coupled to the flame control electrode assembly 170 and may control operation thereof. For example, the combustion controller 190 may bias the flame control and/or regulate electric field produced by the flame control electrode assembly 170.

In some embodiments, the combustion controller 190 may direct the flame control electrode assembly 170 to produce or generate a negative electric field. Alternatively, the combustion controller 190 may direct the flame control electrode assembly 170 to produce a positive electric field. Furthermore, in an embodiment, the combustion controller 190 may determine whether to produce a negative or a positive electric field at least in part based on the information about the net charge of the flame 20. For example, the combustion controller 190 may include a special purpose computer or circuit or a general purpose computer, which may be programmed or otherwise configured to control or operate the flame control electrode assembly 170.

In some instances, as mentioned above, the combustion controller 190 may inject positively or negatively charged particles, such as ions, into the fuel, oxidizer, flame, or combinations thereof. Hence, the combustion controller 190 may use information about the injected ions to determine the net charge of the flame. Additionally or alternatively, the combustion controller 190 may obtain information about the net charge of the flame, which may be used to determine the charge for the electric field. For example, the combustion controller 190 may first direct the flame control electrode assembly 170 to produce a negative electric field, and subsequently, a positive electric field, and may determine the net charge of the flame 20 based on the movement of the flame 20 in response to the produced electric fields. In any event, the combustion controller 190 may direct the flame control electrode assembly 170 in a manner that produces an electric field having that has a charge that is opposite to the net charge of the flame 20.

In some embodiments, the combustion controller 190 may include a voltage source. Alternatively, the combustion controller 190 may be electrically coupled to a voltage source and may couple the voltage source to the flame control electrode assembly 170. In any event, as described below in further detail, the flame control electrode assembly 170 may include multiple flame control electrodes that may be biased to produce an electric field that may have a charge that is opposite to the net charge of the flame 20. Accordingly, the electric field may be at least partially controlled to manipulate movement of ions in the flame 20, which in some embodiment may attract the flame 20 to at least one of the chamber walls 150.

For example, the controlled electric field may create electrostatic forces (e.g., Coulombic body forces) within the flame 20 that may be manipulated to control flame shape, combustion chemistry, heat transfer through or away from a surface (e.g., the surface of the flame control electrode assembly 170), or combinations thereof, as desired or suitable for one or more operating conditions. Also, in some embodiments, the combustion controller 190 may be configured to apply a substantially or suitable constant voltage or time-varying voltage to one or more of the flame control electrodes in the flame control electrode assembly 170 and may generate substantially or suitable constant or time-varying electric field strength (e.g., the strength of the electric field may be suitable to attract and/or more the flame toward the flame control electrode assembly 170).

In an embodiment, the combustion controller 190 and the flame control electrode assembly 170 may be collectively configured to vary application of the electric field to the flame 20 at selected times and/or locations. In alternative or additional embodiments, the combustion controller 190 may be configured to change a polarity of the voltage applied to the one or more of the flame control electrodes in the flame control electrode assembly 170. Also, the combustion controller 190 may be configured to vary a magnitude or frequency of a voltage applied to one or more of the flame control electrodes in the flame control electrode assembly 170 at selected times and/or locations.

In an embodiment, the combustion controller 190 and the flame control electrode assembly 170 may cause a response in the flame 20. For instance, by controlling timing, direction, strength, location, wave form, frequency spectrum of the electric field, or combinations thereof, the combustion controller 190 and flame control electrode assembly 170 may cooperate to influence combustion characteristics of the flame 20, such as the shape of the flame 20, position of the flame 20 within the combustion chamber 120 (e.g., position relative to the wall chamber 150), heat transfer from the flame 20, or combinations thereof.

Additionally or alternatively, causing a response in the flame 20 may include causing increased mixing of fuel and oxidizer in the flame 20. In an embodiment, causing the increased mixing of fuel and oxidizer may increase a rate of combustion. In some embodiments, causing the increased mixing of fuel and oxidizer may increase fuel and oxidizer contact in the flame 20. Moreover, causing the increased mixing of fuel and oxidizer may decrease a flame temperature.

In an embodiment, causing the increased mixing of fuel and oxidizer may decrease an evolution of oxides of nitrogen (“NOx”) by the flame 20. In some instances, causing the increased mixing of fuel and oxidizer may decrease an evolution of carbon monoxide (“CO”) by the flame 20. Furthermore, causing the increased mixing of fuel and oxidizer may increase flame stability and/or decrease a chance of flame blow-out. Also, causing the increased mixing of fuel and oxidizer may increase flame emissivity. In alternative or additional embodiments, causing the increased mixing of fuel and oxidizer may decrease flame size for a given fuel flow rate.

As noted above, attracting fuel mixture and/or the 20 to the flame control electrode assembly 170 may reduce the combustion temperature inside the combustion chamber 120, thereby reducing NOx produced by the combustion system 100. More specifically, in some embodiments, the flame control electrode assembly 170 and/or one or more of the chamber walls 150 may absorb and/or transfer heat away from the flame 20, thereby reducing temperature thereof. In turn, in some embodiments, reducing combustion temperature of the flame 20 may reduce the amount NOx produced during combustion.

In some embodiments, the flame control electrode assembly 170 and/or the chamber walls 150 may be in thermal communication with a cooling element, such as a heat sink, a heat exchanger, a similar cooling structure, or combinations thereof, which may transfer the heat away from the flame control electrode assembly 170 and chamber walls 150, thereby reducing temperature thereof. Hence, attracting the flame 20 to the flame control electrode assembly 170 and/or to the chamber walls 150 may transfer heat away from the flame 20 to the flame control electrode assembly 170 and/or to the chamber walls 150 (i.e., since the flame control electrode assembly 170 and/or to the chamber walls 150 may be continuously or intermittently cooled by a cooling element). It should be appreciated that the flame control electrodes of the flame control electrode assembly 170 may include thermally conductive material, which may transfer heat from the flame (i.e., the flame control electrodes of the flame control electrode assembly 170 may form a heat sink).

In one or more embodiments, the combustion system 100 may include a heat exchanger that may circulate a cooling fluid therethrough, which may cool the flame control electrode assembly 170. As noted above, in some instances, the cooling element may be thermally coupled to the flame control electrode assembly 170. Alternatively or additionally, the cooling structure may be integrated within the flame control electrode assembly 170 (e.g., the flame control electrode assembly 170 may include fluid channels for circulating a cooling fluid through the flame control electrode assembly 170). Such fluid may cool the flame control electrode assembly 170 and produce a temperature differential between the flame control electrode assembly 170 and the flame 20 to facilitate heat transfer therebetween. In any event, the heat from the flame 20 may be transferred to the flame control electrode assembly 170 and/or the chamber walls 150 to cool the flame 20 and reduce NOx produced during combustion. In some embodiments, the heat removed from the flame electrode assembly 170 (e.g., heat transferred to the cooling fluid) may be used to heat one or more elements or components.

FIGS. 1C and 1D illustrate an enlarged view of the flame 20 before and after activation of the flame control electrode assembly 170. More specifically, FIG. 1C shows the flame 20 during combustion inside the combustion chamber, but before activation of the flame control electrode assembly 170. As illustrated in FIG. 1D, after the flame control electrode assembly 170 is activated, the flame control electrode assembly 170 attracts the flame 20 to the flame control electrode assembly 170 and to the chamber walls 150. As described above, heat from the flame 20 may be transferred to the chamber walls 150 and/or to the flame control electrode assembly 170.

For example, the flame 20 may convectively transfer heat to the chamber walls 150 and/or to the flame control electrode assembly 170. Additionally or alternatively, the flame 20 may contact the chamber walls 150 and/or the flame control electrode assembly 170. Hence, in one or more embodiments, the flame 20 may conductively transfer heat therefrom to the chamber walls 150 and/or to the flame control electrode assembly 170. In any case, in one or more embodiments, the flame 20 may transfer heat to the chamber walls 150 and/or to the flame control electrode assembly 170, which may reduce combustion temperature of the flame 20.

Generally, the flame control electrodes of the flame control electrode assembly 170 may have any number of suitable configurations and arrangements. For example, FIG. 2 illustrates a flame control electrode assembly 170a that includes flame control electrodes 200a spaced from each other. Except as otherwise described herein, the flame control electrode assembly 170a and its materials, elements, and components may be similar to or the same as the flame control electrode assembly 170 (FIGS. 1A-1B) and its corresponding materials, elements, and components. In some embodiments, similar to the flame control electrode assembly 170 (FIGS. 1A-1B), the flame control electrode assembly 170a may be electrically coupled to the combustion controller 190, which may control operation of the flame control electrode assembly 170a (e.g., in a manner described above).

In one or more embodiments, the flame control electrodes 200a may be at least partially or entirely encapsulated in one or more insulation elements, such as in an insulation element 210a. For instance, the flame control electrodes 200a may be overmolded in glass, which may form the insulation element 210a when cooled. Additionally or alternatively, the flame control electrodes 200a may be enclosed or encapsulated between two glass sheets, which may be fused together (as described below in more detail) to form a substantially unitary and/or monolithic insulation element.

The flame control electrodes 200a may include any suitable electrically conductive material that may vary from one embodiment to the next. In some examples, the flame control electrodes 200a may include any of the following materials: copper, aluminum, alloys thereof, similar materials (e.g., electrically conductive materials), or combinations thereof. Alternatively or additionally, in some embodiments, the flame control electrodes 200a may include refractory materials, such as molybdenum, tungsten, niobium, tantalum, rhenium, alloys of the foregoing, combinations thereof, or any other suitable material.

In some embodiments, the flame control electrodes 200a may have an approximately circular cross-section. For example, the flame control electrodes 200a may be wires of a suitable wire gauge. Also, as described in further detail below, the flame control electrodes 200a may have any number of suitable cross-sections, which may vary from one embodiment to the next.

The insulation element 210a may include any suitable material. Generally, the insulation element 210a may include materials suitable for electrically insulating the flame control electrodes 200a (e.g., sufficient insulation to prevent shorting the flame control electrodes 200a by charged particles of the flame). Furthermore, materials that form the insulation element 210a also may withstand temperatures inside the combustion chamber and protect the flame control electrodes 200a from such temperatures (e.g., thermally insulating the flame control electrodes 200a to prevent damage thereof). For example, the insulation element 210a may include quartz glass. It should be appreciated, however, that the insulation element 210a may include other suitable materials, such as other ceramics and the like.

The insulation element 210a also may encapsulate connections from the combustion controller 190 to the flame control electrodes 200a. For example, the flame control electrodes 200a may be wired or otherwise connected together in a manner that allows the combustion controller 190 to connect to the flame control electrode assembly 170a at a single location. In some examples, alternating flame control electrodes of the flame control electrodes 200a may be electrically coupled in parallel to provide two opposite polarity connection locations for the combustion controller 190.

Alternatively, the combustion controller 190 may couple to the flame control electrodes 200a at multiple locations. As such, the combustion controller 190 and the flame control electrode assembly 170a may generate multiple electric fields that may vary from one location to another or may be the same. For example, the flame control electrode assembly 170a may generate a stronger electric field at one or more locations that are farther away from the fuel outlet or nozzle than at locations closer to the fuel outlet, or vice versa. It should be also appreciated that the electric field generated by the flame control electrode assembly 170a and combustion controller 190 may continuously vary along the length (i.e., in a direction away from the fuel supply) of the flame control electrode assembly 170a and chamber walls 150a.

The electric field also may vary based on the flame or combustion characteristics. In some embodiments, the combustion controller 190 may automatically regulate or adjust the electric field generated by the flame control electrode assembly 170a and combustion controller 190 in a manner that attracts the flame to the flame control electrode assembly 170a. In any case, the flame control electrode assembly 170a may attract the flame thereto and, thus, to the chamber walls, such as chamber wall 150a.

The flame control electrode assembly 170a may be mounted on the chamber wall 150a in any number of suitable ways. For example, the flame control electrode assembly 170a may be fastened, adhered, or otherwise secured to or integrated with the chamber wall 150a. As described above, in one or more embodiments, a cooling device, such as a heat exchanger may be in thermal communication with the flame control electrode assembly 170a. In particular, in some embodiments, a cooling device may be located between the flame control electrode assembly 170a and the chamber wall 150a. Alternatively, the cooling device may be incorporated into the chamber wall 150a and/or into the flame control electrode assembly 170a (e.g., cooling lines may be included in the chamber wall 150a and/or in the flame control electrode assembly 170a at suitable locations).

Insulation elements may have a sheet- or plate-like shape and may secure and insulate flame control electrodes therebetween. Hence, for example, the flame control electrode assembly may include two or more fused glass sheets or elements that may at least partially insulate one or more flame control electrodes of the flame control electrode assembly. FIG. 3, for example, illustrates a flame control electrode assembly 170b that includes insulation elements 210b and 210b′ that encapsulate flame control electrodes 200b. Except as otherwise described herein, the flame control electrode assembly 170b and its materials, elements, and components may be similar to or the same as any of the flame control electrode assemblies 170, 170a (FIGS. 1A-2) and their corresponding materials, elements, and components. In some embodiments, the insulation elements 210b and 210b′ may comprise similar or the same material, such as quartz glass.

Alternatively, the insulation elements 210b and the 210b′ may include dissimilar materials. For instance, the insulation element 210b may include refractory ceramic, while the insulation elements 210b′ may include glass. Moreover, while in some embodiments, the insulation elements 210b and 210b′ may be fused together, in other embodiments, the insulation elements 210b and 210b′ may be bonded, adhered, fastened, or otherwise secured together. Also, in some examples, (e.g., when the insulation elements 210b and 210b′ are bonded or otherwise secured together), the materials included in the insulation elements 210b may have similar or the same coefficient of thermal expansion as the materials included in the insulation elements 210b′. Embodiments also may include the insulation elements 210b and 210b′ that have different coefficients of thermal expansion (e.g., bonding material between the insulation elements 210b and 210b′ may accommodate different rates of thermal expansion of the insulation elements 210b, 210b′, flame control electrodes 200b, and combinations thereof).

In an embodiment, the insulation elements 210b and 210b′ may be first secured together (with the flame control electrodes 200b sandwiched therebetween) and then mounted or secured on the chamber wall 150b. In alternative or additional embodiments, the insulation element 210b may be first mounted on the chamber wall 150b and, subsequently, the insulation element 210b′ may be secured to the insulation element 210b and to the chamber wall 150b. Also, in some instances, the flame control electrodes 200b may be secured to or at least partially within the insulation element 210b before securing the insulation element 210b to the insulation element 210b and/or to the chamber wall 150b. Optionally, the insulation element 210b may be first secured to the chamber wall 150b and thereafter, the flame control electrodes 200b may be secured to and/or within the insulation element 210b.

Furthermore, the flame control electrodes may be first secured to a wall and subsequently insulated and/or at least partially enclosed or encapsulated by one or more insulation elements. FIG. 4, for example, illustrates a flame control electrode assembly 170c that includes flame control electrodes 200c positioned near or on the chamber wall 150c. Except as otherwise described herein, the flame control electrode assembly 170c and its materials, elements, and components may be similar to or the same as any of the flame control electrode assemblies 170, 170a, 170b (FIGS. 1A-3) and their corresponding materials, elements, and components.

In particular, in some embodiments, the flame control electrodes 200c may be secured to or mounted on the chamber wall 150c in any number of suitable ways, which may at least temporarily attach the flame control electrodes 200c to the chamber wall 150c. For example, the flame control electrodes 200c may be attached to the chamber wall 150c with an adhesive, by wrapping portions of the flame control electrodes 200c about one or more post on the chamber wall 150c (e.g., around screws, nails, etc.), among others. Subsequently, at least partially molten glass may be pressed against the chamber wall 150c and the flame control electrodes 200c to form the insulation element 210c about the flame control electrodes 200c. Furthermore, in some instances, the insulation element 210c may secure the flame control electrodes 200c to the chamber wall 150c.

Alternatively, however, the flame control electrodes 200c may be positioned at least partially inside or embedded within the insulation element 210c, while the material of the insulation element 210c may be in a softened state (e.g., partially molten). Thereafter, the insulation element 210c may be pressed against and/or adhered to the chamber wall 150c. Also as mentioned above, the flame control electrode assembly 170c may be fastened or otherwise secured to the chamber wall 150c. For instance, the insulation element 210c may assume its hardened or final state before the flame control electrode assembly 170c is mounted on the chamber wall 150c.

Moreover, embodiments of the invention are not limited insulation elements that include glass. Accordingly, for example, insulation elements, such as the insulation element 210c, may include any number of suitable materials that may be secured to the chamber wall 150c. Likewise, suitable materials for the insulation elements also may allow placement of the flame control electrodes 200c at least partially inside the insulation element 210c before mounting the insulation element 210c to the chamber walls 150.

While in some embodiments flame control electrodes of the flame control electrode assembly may be positioned inside a single insulation element, in additional or alternative embodiments, at least some of the flame control electrodes may be at least partially wrapped and/or encapsulated in an electrically insulating material. FIG. 5, for example, illustrates a flame control electrode assembly 170d that include individually insulated flame control electrodes 200d. Except as otherwise described herein, the flame control electrode assembly 170d and its materials, elements, and components may be similar to or the same as any of the flame control electrode assemblies 170, 170a, 170b, 170c (FIGS. 1A-4) and their corresponding materials, elements, and components.

For example, the flame control electrodes 200d may have an approximately circular cross-section and may be encapsulated in insulation elements 210d that have at least a partially circular cross-section (e.g., insulation elements 210d may form insulation, which has at least a portion that has approximately uniform thickness). Moreover, the insulation elements 210d may be at least partially flattened or molten, such as at a base thereof, in a manner that may attach the insulation elements 210d to the chamber wall 150d. Consequently, in some embodiments, each of the flame control electrodes 200d (and the insulation elements 210d) may be attached to the chamber wall 150d independently of other flame control electrodes 200d. Such configuration may facilitate scaling of the combustion system. Additionally or alternatively, such configuration may facilitate removal and/or replacement of the flame control electrodes 200d (e.g., replacement damaged flame control electrodes 200d, removal of unnecessary flame control electrodes 200d, etc.).

Also, in some embodiments, the insulation elements 210d may have hollow shapes or tubular configuration. For example, the insulation elements 210d may be extruded to form the tubular shapes thereof. In any event, in an embodiment, the flame control electrodes 200d may be inserted into and/or secured within the insulation elements 210d. In some instances, the electrodes 200d may be first inserted into the insulation elements 210d and subsequently, the insulation elements 210d together with the flame control electrodes 200d may be mounted on the chamber wall 150d. Alternatively, the insulation elements 210d may be first mounted on the chamber wall 150d, and subsequently, the flame control electrodes 200d may be inserted into and/or secured within the insulation elements 210d.

Furthermore, as described above, the flame control electrodes of the flame control electrode assembly may have any number of suitable cross-sectional shapes. Generally, in one or more embodiments, the flame control electrodes may be elongated and/or wire-like members, which may extend along one or more chamber walls. In some embodiments, as shown in FIG. 6, the flame control electrodes may have an approximately rectangular cross-section. More specifically, FIG. 6 illustrates a flame control electrode assembly 170e that includes flame control electrodes 200e mounted on the chamber wall 150e. Except as otherwise described herein, the flame control electrode assembly 170e and its materials, elements, and components may be similar to or the same as any of the flame control electrode assemblies 170, 170a, 170b, 170c, 170d (FIGS. 1A-5) and their corresponding materials, elements, and components.

In some examples, the flame control electrodes 200e may have no insulation or may have a thin insulating coating thereon. For instance, the flame control electrodes 200e may be spaced apart in a manner that prevents or minimize occurrences of shorting therebetween (e.g., which may be caused by the charged particles in the flame). In any event, some embodiments may include uninsulated flame control electrodes 200e. Moreover, in at least one embodiment, the uninsulated flame control electrodes 200e may provide increased heat transfer from the flame (as compared with the insulated flame control electrodes).

As noted above, the cross-sectional shape of the flame control electrodes may vary from one embodiment to the next. Likewise, the cross-sectional shape of the insulation placed about the flame control electrodes may vary from one embodiment to another. Similarly, cross-sectional shapes of the insulation may vary from one embodiment to another. In an embodiment, as shown in FIG. 7, a flame control electrode assembly 170f may include flame control electrodes 200f encased/encapsulated in insulation elements 210f, 210g. Except as otherwise described herein, the flame control electrode assembly 170f and its materials, elements, and components may be similar to or the same as any of the flame control electrode assemblies 170, 170a, 170b, 170c, 170d, 170e (FIGS. 1A-6) and their corresponding materials, elements, and components. For example, the flame control electrode assembly 170f may be mounted or secured to the chamber wall 150f in the same or similar manner as described above.

In some embodiments, the insulation elements 210g and/or 210f may be at least partially melted or softened in a manner that may bond the insulation elements 210g and/or 210f to the chamber wall 150f, thereby securing the flame control electrodes 200f to the chamber wall 150f Also, the insulation elements 210f and 210g may be bonded to one another, thereby forming substantially uniform insulation elements 210fg. Moreover, as mentioned above, the insulation elements 210fg formed by the insulation elements 210f and 210g may have different shapes (e.g., different cross-sectional shapes) than the flame control electrodes 200f. In the illustrated example, the insulation elements 210fg have approximately square cross-sectional shapes, while the flame control electrodes 200f have approximately circular cross-sectional shapes. It should be appreciated, however, that the flame control electrodes and the insulation elements may have any suitable cross-sectional shape (e.g., circular, rectangular, oval, irregular, etc.), which may vary from one embodiment to the next.

Embodiments of the invention also may include a method reducing NOx produced by any of the combustion systems disclosed herein. For example, as illustrated in FIG. 8, the method may include an act 310 of arranging at least one flame control electrode assembly inside a combustion chamber. In particular, embodiments may involve securing at least one flame control electrode assembly to one or more walls of the combustion chamber. As described above, the flame control electrode assembly may be operably connected to a controller that may control operation of the flame control electrodes. In some instance, the controller may additionally or alternatively control operation of one or more ionizers, which may charge the fuel, oxidizer, flame, or combinations thereof.

The method also may include an act 320 of biasing the flame control electrodes to generate an electric field. For instance, the controller may apply a voltage to the flame control electrodes in a manner that produces an electric field near the chamber wall. The controller also may vary the voltage to adjust the electric field based on combustion of fuel (e.g., based on the amount of fuel and/or oxidizer injected into the combustion chamber, flame temperature, etc.).

Moreover, the method may include an act 330 of attracting a flame to one or more chamber walls of the combustion chamber. In some embodiment, the flame may be attracted to the chamber walls or portions thereof located between the fuel nozzle(s) and the flue. In any case, in an embodiment, the controller may apply sufficient voltage to flame control electrode assembly to produce a suitable electric field that may attract the flame to the chamber walls.

For example, as mentioned above, the flame may have a net positive or negative charge, which may result from ionizing the fuel and/or the oxidizer. In alternative or additional embodiments, ions may be injected directly into the flame to produce a net charge. Hence, in at least one embodiment, the flame may have a net charge, and the flame control electrode assembly and controller may produce an oppositely charged electric field that may be located near one or more chamber walls. As such, the flame control electrode assembly may attract the flame to one or more chamber walls.

When the flame is attracted to the chambers walls, heat from the flame may be transferred to the chamber walls, thereby reducing combustion temperature of the flame. In some instances, reducing combustion temperature of the flame may reduce NOx produced during combustion. Accordingly, in some embodiments, the method includes an act 340 of dissipating heat from the flame to reduce NOx. It should be appreciated that heat transferred from the flame to chamber walls may be further dissipated from the walls (e.g., to environment outside of the combustion chamber and/or to one or more elements or components intended to be heated).

The present 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 that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A combustion system, comprising:

a combustion chamber including at least one chamber wall;

a source of combustible fuel for producing a flame in the combustion chamber; and

a flame control electrode assembly mounted to the at least one chamber wall, the flame control electrode assembly including a plurality of flame control electrodes, the flame control electrode assembly being configured to produce an electric field and attract the flame toward the at least one chamber wall.

2. The system of claim 1, further comprising a controller electrically coupled to the flame control electrode assembly, the controller being configured to regulate the electric field produced by the flame control electrode assembly.

3. The system of claim 3, wherein the controller is configured to regulate the electric field produced by the flame control electrode assembly at least in part based on the net charge of the flame.

4. The system of claim 1, wherein one or more of the plurality of flame control electrodes is at least partially enclosed by one or more insulation elements.

5. The system of claim 4, wherein the one or more insulation elements include a plurality of insulation elements, and at least one of the plurality of flame control electrodes is encapsulated between multiple insulation elements bonded together.

6. The system of claim 4, wherein at least one of the one or more insulation elements has a tubular shape, and at least one of the plurality of flame control electrodes is located within a hollow space of the tubular shape.

7. The system of claim 4, wherein at least one of the one or more insulation elements is secured to the at least one chamber wall.

8. The system of claim 4, wherein the one or more insulation elements have sheet-like shapes and at least some of the flame control electrodes are located between the sheet-like shaped insulation elements that are bonded together.

9. The system of claim 4, wherein the flame control electrodes are embedded within at least one of the one or more insulation elements.

10. The system of claim 4, wherein the plurality of flame control electrodes include a refractory material and the one or more insulation elements include electrically insulating material.

11. The system of claim 1, further comprising one or more heat exchangers configured to transfer heat from the combustion chamber.

12. A method of reducing NOx produced during combustion in a combustion chamber, the method comprising:

combusting a fuel inside of the combustion chamber to produce a flame having a net positive charge or net negative charge;

producing an electric field having a charge opposite to the flame charge, the electric field being positioned near at least one chamber wall of the combustion chamber;

attracting the flame toward the at least one chamber wall; and

transferring heat from the flame to the at least one chamber wall to thereby reduce a combustion temperature of the flame.

13. The method of claim 12, wherein producing an electric field having a charge opposite to the flame charge includes biasing a flame control electrode assembly positioned near the at least one chamber wall.

14. The method of claim 13, wherein producing an electric field having a charge opposite to the flame charge includes determining the net charge of the flame.

15. The method of claim 13, further comprising at least partially electrically insulating a plurality of flame control electrodes of the flame control electrode assembly by one or more insulating elements.

16. The method of claim 15, wherein at least one of the flame control electrodes is embedded within the one or more insulating elements.

17. The method of claim 13, wherein transferring heat from the flame includes transferring heat to one or more of the at least one chamber wall or the flame control electrode assembly.

18. The method of claim 17, further comprising transferring heat from one or more of the at least one chamber wall or the flame control electrode assembly to a first heat exchanger.

19. The method of claim 12, wherein combusting a fuel inside of the combustion chamber to produce a flame having a net positive charge or net negative charge includes injecting positively or negatively charged particles into one or more of the fuel, an oxidizer, or the flame.

20. A combustion system, comprising:

a combustion chamber including at least one chamber wall;

a source of combustible fuel for producing a flame in the combustion chamber;

at least one ionizer positioned and configured to ionize one or more of the fuel, combustion air, or the produced flame;

a flame control electrode assembly mounted to the at least one chamber wall, the flame control electrode assembly including a plurality of flame control electrodes that are electrically insulated from each other, the flame control electrode assembly being configured to produce an electric field that attracts the flame toward the at least one chamber wall; and

a controller electrically coupled to the flame control electrode assembly, the controller being configured to regulate the electric field produced by the flame control electrode assembly.