COMBUSTION SYSTEM INCLUDING AT LEAST ONE FUEL FLOW EQUALIZER

Abstract

Embodiments disclosed herein are directed to a combustion system including at least one fuel flow equalizer for reducing fuel flow velocity distribution and improving flame stabilization within a combustion space. Additionally, a charged flame anchoring apparatus may be positioned above the at least one fuel flow equalizer for attaching the flame thereto and improving flame stability.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 61/764,267 filed 13 Feb. 2013, which, to the extent not inconsistent with the disclosure herein, is incorporated by reference.

BACKGROUND

Fuel injection at high speed into a combustion zone may contribute to or cause instabilities in flame position and shape of a flame. High fuel injection speeds can result in non-uniform fuel distribution and unstable flame propagation within the combustion space, which can cause such problems such as poor combustion, increased emissions of pollutants, flashback, poor heat transfer, reduced component life, and potential system damages among others.

Flame stabilization can be required in combustion systems to prevent a combustion flame front from moving upstream from a desired combustion zone toward a source of introduced fuel, causing a flashback that can damage structures within the fuel-air mixing region of the combustion system. Flame stabilization can also be dependent upon the speed at which the fuel-air mixture enters the combustion zone where propagation of the flame can be desired. A sufficiently low velocity can be retained in the region where the flame can be desired in order to sustain the flame. A region of low velocity can be achieved by causing recirculation of a portion of the fuel-air mixture already burned, thereby providing a source of ignition to the fuel-air mixture entering the combustion zone. However, the fuel-air mixture flow pattern, including any recirculation, is one important factor to achieving flame stability.

Flame stability can be achieved by placement of a bluff body in the flow path of a fuel-air mixture within a combustion zone. A bluff body typically defines a leading edge and a trailing edge, and separation of a mixture passing over the bluff body occurs at the trailing edge of the bluff body thereby forming a wake downstream of the trailing edge. The velocity of the fuel-air mixture in the wake region can be much lower than the velocity of the fuel-air mixture flowing in the main stream around the bluff body thereby supporting recirculation. One problem associated with using a bluff body can be that the flame can be anchored to the bluff body and the excessive heat can be life-limiting.

One approach for promoting a stable flame in a combustion system to promote low emissions, can be placement of a swirler downstream, but this approach has been disadvantageous in that a flashback event, such as from a flow disturbance, can destroy the swirler. Also, adequate mixing downstream of a swirler can be difficult to achieve.

Furthermore, methods for stabilizing flames can include using charged anchoring apparatuses for attaching flames and better controlling their position and shape. Although these apparatuses can be favorable for flame stabilization, subsonic and/or supersonic speeds of fuel flow being injected into combustion volumes can make flame control more difficult, especially when attempting to stabilize flames at very high BTU levels.

SUMMARY

Embodiments disclosed herein are directed to various combustion systems configured for fuel flow equalization and stabilization of a flame in a combustion space. In an embodiment, a combustion system includes at least one burner nozzle, a fuel flow equalizer, at least one flame anchoring apparatus, and a voltage power supply. The at least one burner nozzle is configured to discharge fuel into a combustion space sized and configured to at least partially contain a flame produced during combustion of the fuel and an oxidizer (e.g., air). The at least one fuel flow equalizer is positioned downstream from the at least one burner nozzle, and includes a plurality of openings sized and configured to allow the fuel to pass therethrough. The flame anchoring apparatus is positioned downstream from the at least one fuel flow equalizer. The voltage power supply is electrically coupled to the flame anchoring apparatus. The voltage power supply is configured to bias the flame anchoring apparatus so that the flame is attracted to the flame anchoring apparatus.

In an embodiment, a method for stabilizing a flame within a combustion space is disclosed. A stream including fuel is discharged from at least one nozzle into a combustion space. The fuel is passed through at least one fuel flow equalizer structure positioned downstream from the at least one nozzle. The fuel and an oxidizer (e.g., air) is ignited to produce a flame. An electrical potential is applied to a flame anchoring apparatus effective to anchor the flame to the flame anchoring apparatus.

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

FIG. 1A illustrates a velocity distribution of fuel and a respective shape of a flame within a combustion space, according to an example.

FIG. 1B illustrates the behavior of a flame according to fuel flow velocity distribution, according to an example.

FIGS. 2A and 2B illustrate a velocity distribution of fuel and a respective shape of a flame within a combustion space employing a fuel flow equalizer disposed between a fuel nozzle and a flame, according to embodiments.

FIGS. 3A-3F illustrate different shapes and patterns for fuel flow equalizer, according to embodiments.

FIG. 4 illustrates a combustion system including any of the fuel flow equalizers disclosed herein and a flame anchoring apparatus, according to an embodiment.

DETAILED DESCRIPTION

Embodiments disclosed herein are directed to various combustion systems configured for fuel flow equalization and stabilization of a flame in a combustion space. As used herein, a “fuel flow equalizer” refers to a device that can be employed for spreading and/or substantially equalizing a combustible fuel and/or fuel mixture and reducing speed of the combustible fuel and/or fuel mixture for a combustion reaction in a manner that may improve flame stability. As used herein, “flame stability” refers to a capability of a flame being supported without blowing out, which can be achieved when fuel flow velocity and flame speed are approximately equal. As used herein, an “anchoring apparatus” refers to an electrically conducting device located at least proximate to a flame and configured for coupling the flame thereto in a manner that may improve flame stability.

According to various embodiments disclosed herein, a combustion system may include a fuel flow equalizer may also promote rapid mixing of fuel/air flow streams for complete fuel combustion within the combustion space. The fuel flow equalizer may be arranged in the path of fuel flow and can include any number of suitable materials such as metallic materials, which may be capable of withstanding high pressures and temperatures. The fuel flow equalizer may exhibit various geometric configurations having, different shapes and patterns that may provide increased flame stability and spread or equalize velocity of the fuel flow in a high area near and/or in the combustion zone. Different shapes of the fuel flow equalizer can include square, circular, and rectangular, among others, while the different patterns can include honeycomb patterns, cylindrical patterns, and other mesh patterns.

The fuel flow equalizer may also include a plurality of fuel flow paths depending on the combustion system, with each path being defined by mean hydraulic diameter and spatial orientation of the opening in the fuel flow equalizer, and take into account the fuel and fuel/air ratio. The configuration of this embodiment may produce a shaped flame that may move outward from the middle when its equivalent ratio may increase and may become very tight, positioning the flame away from the fuel flow equalizer, achieving stable combustion with very low emissions (NOx, CO, and HC) and nonexistent large-scale acoustics. Additionally, the maximum velocity of fuel-air flow may be reduced immediately after the nozzle and uniformly distributed when passing through the fuel flow equalizer in the combustor.

In large combustion volumes, large flames may be under relatively high pressure and may behave rapidly, making it difficult to pull down the flames. The fuel flow equalizer may help in stabilizing powered flames and provide suitable aerodynamic fuel equalization.

According to other embodiments, in addition to improving flame stability by reducing fuel flow velocity with the fuel flow equalizer, flame stability may be further enhanced or improved by adding a flame anchoring apparatus (e.g., an electrically charged and electrically conductive anchoring apparatus), which may be positioned downstream from the fuel flow equalizer. As such, both the fuel flow equalizer and the anchoring apparatus may lead to firm attachment or coupling of the flame to the anchoring apparatus. The fuel flow equalizer may be configured in a manner that facilitates positioning the flame above the anchoring apparatus (i.e., downstream) or below the anchoring apparatus (i.e., upstream from), as may be required or suitable for a particular application.

Embodiments disclosed herein may facilitate rapid mixing of fuel and air resulting in a compact combustion zone. Additionally or alternatively, embodiments disclosed herein may facilitate flame stabilization and fuel velocity control that may allow slowing down the velocity of the flame to the extent that the flame can or does not anchor to the fuel flow equalizer but instead anchors to the anchoring apparatus. The fuel flow equalizer may be a mechanical device for spreading and enlarging flames aerodynamically.

From an aerodynamic point of view, a fuel flow equalizer may overcome limitations of known combustion system which can present difficulties holding flames away from electrodes comprising the anchoring apparatus at very high BTU levels. The embodiments disclosed herein may minimize emissions by aerodynamically anchoring the flame.

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, which are not to scale or to proportion, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings and claims, are not meant to be limiting. Other embodiments may be used and/or and other changes may be made without departing from the spirit or scope of the present disclosure.

FIGS. 1A and 1B illustrate operation of a burner without a fuel flow equalizer. More specifically, FIG. 1A illustrates an example of fuel distribution as fuel 102 exists a burner nozzle 104. In some embodiments, the burner nozzle 104 may inject the fuel 102 into a combustion space 106. Generally, the burner nozzle 104 injects the fuel 102 downstream therefrom, as indicated by the arrows.

The combustion space 106 may be an open or at least partially closed chamber, which may include one or more structures (e.g., chamber walls) that may at least partially enclose the fuel 102 and the flame combusted from the fuel 102 therein. Hence, the combustion space 106 may be formed or defined by one or more chamber walls, which may collectively form the combustion space. In some embodiments, at least a portion of the burner nozzle 104 also may be included inside the combustion space. Alternatively, however, the combustion space may be at least mostly open (i.e., the fuel 102 may be injected into a natural, outside environment and may combust therein).

The fuel 102 may be ignited and/or combusted downstream from the burner nozzle 104 to form a flame. Hence, in an embodiment, the fuel 102 may be mixed with an oxidizer (e.g., air, oxygen, etc.), which may promote and/or facilitate combustion of the fuel 102. In some embodiments, the fuel 102 may be premixed with the oxidizer and may exit the burner nozzle 104 together therewith. Alternatively, the fuel 102 may at least partially mix with the oxidizer inside the combustion space 106.

In some instances, without the fuel flow equalizer, a velocity of the fuel 102 within the combustion space varies with distance from the burner nozzle 104. More specifically, near the burner nozzle 104 the fuel 102 has higher velocity than farther away from the burner nozzle 104. In other words, as the fuel 102 flows downstream and away from the burner nozzle 104, the velocity of the fuel 102 decreases.

In some instances, velocity zones may be defined as velocity zones V₁, V₂, and V₃. As noted above, velocity of the fuel 102 in the V₁ zone may be higher than in V₂ and V₃. Likewise, velocity of the fuel 102 in the V₂ zone may be less than in the V₁ zone but greater than in the V3 zone (i.e., in some embodiments, V₁>V₂>V₃). It should be also appreciated that velocity of the fuel 102 may vary within any of the V₁, V₂, and V₃ zone (e.g., velocity of the fuel 102 that is closer to the downstream end of the zone may be lower than at the upstream end thereof). In some examples, velocities of the fuel 102 in the V₁ zone may be near sonic (i.e., subsonic) or supersonic.

FIG. 1B illustrates an example of a flame formed during combustion of the fuel and oxidizer mixture shown in FIG. 1A. In particular, FIG. 1B illustrates a flame 108 combusted in the combustion space 106, and the behavior of the flame 108 according to the velocity distribution of the fuel 102 (shown in FIG. 1A). The fuel flow velocities near the burner nozzle 104 may be high subsonic, making control of the flame 108 more difficult in the areas closer to the burner nozzle 104.

Generally, an ignition source or an igniter may ignite the fuel and oxidizer mixture to initiate combustion and produce the flame 108. In some embodiments, the ignition source may be a pilot light. Alternatively, the ignition source may include a spark igniter (e.g., a piezo igniter) may ignite the fuel and oxidizer mixture to produce the flame 108. In any event, the ignition source may include any number of suitable mechanisms and devices that may ignite the fuel and oxidizer mixture to produce the flame 108.

In some instances, the flame 108 may be easier to control at lower velocities of flow. In the absence of a fuel flow equalizer, different factors may affect combustion and stability of the flame 108. Such factors include, but are not limited to, heat requirement variations, weather, and componentry wear or damage, among others. In some instances, combustion of the fuel flowing at high speeds may produce increased emissions of pollutants (e.g., NOx, CO, HC, etc.), flash back, poor heat transfer, reduced component life, unplanned shutdowns, potential system damage, etc.

The flame 108 may include a variety of charged and uncharged particles and molecules. The volume of charged particles may include electrons 110, positive ions 112, negative ions, positively and negatively charged particles, positively and negatively charged fuel vapor, and positively and negatively charged combustion products. Locations, quantities or volume of various charged particles within the flame 108 may vary from one embodiment to the next as well as during the combustion process.

In addition to or in lieu of the charged particles, the flame 108 may include uncharged combustion, unburned fuel and oxidizer, such as air. Moreover, generally, the charged particles have been viewed as transient. Hence, the charged particles typically have not been manipulated. In some embodiments, reducing and/or controlling the velocity of the fuel flow may lead to a more stable combustion and flame.

FIGS. 2A and 2B illustrate a velocity profile of a fuel flow controlled and/or regulated by a fuel flow equalizer 202 and combustion of the fuel, respectively. More specifically, as illustrated in FIG. 2A, the fuel flow equalizer 202 may be placed downstream from the burner nozzle 104, such that the flow of the fuel 102 may interact with the fuel flow equalizer 202. As noted above and as described in further detail below, the fuel flow equalizer 202 may interact with the flow of the fuel 102 in a manner that produces a suitable or selected flow velocity of the fuel 102 downstream from the fuel flow equalizer 202.

In one or more embodiments, the fuel flow equalizer 202 may be placed downstream from a velocity zone V_1a, which may have the same or similar flow velocities and/or velocity distribution as the V₁ zone (FIGS. 1A and 1B). For example, the fuel flow equalizer 202 may be placed in a velocity zone V_2a. Hence, a portion of the flow of fuel 102 within the V_2a zone may have a different velocity profile than another portion of the flow of the fuel 102. In particular, the portion of the flow of the fuel 102 upstream from the fuel flow equalizer 202 may have higher velocity than the portion of the flow of the fuel 102 downstream from the fuel flow equalizer 202. It should be also appreciated that zones V_1a, V_2a, V_3a are chosen for descriptive purposes only and provide a distance and flow velocity reference relative to the burner nozzle 104. Thus, the flow of the fuel 102 may have any number of velocity zones and the fuel flow equalizer 202 may be positioned within one or more of such zones.

In some embodiments, the fuel flow equalizer 202 may be generally planar. In other words, at least one side of the fuel flow equalizer 202 may be approximately flat. Moreover, in some embodiments, the fuel flow equalizer 202 may be positioned approximately perpendicular to the burner nozzle 104, for instance, such that the planar or flat side of the fuel flow equalizer 202 is substantially perpendicular to an imaginary centerline that passes through the burner nozzle 104. It should be appreciated, however, that the fuel flow equalizer 202 also may have non-planar configurations. Furthermore, the fuel flow equalizer 202 may be oriented at any number of suitable orientations relative to the burner nozzle 104 and/or to the flow of the fuel 102, and orientations may vary from one embodiment to the next.

The fuel flow equalizer 202 may be supported downstream from the burner nozzle 104 in any number of ways. For example, a stand, multiple posts, or other elements and/or components may secure the fuel flow equalizer 202 to a support surface near the burner nozzle 104 (e.g., to a floor of the combustion space). Additionally or alternatively, the fuel flow equalizer 202 may be secured to one or more walls that may form or define the combustion space. In any event, the fuel flow equalizer 202 may be positioned at a suitable location and orientation downstream from the burner nozzle 104.

In an embodiment, the flow of the fuel 102 may have an approximately uniform distribution after passing through and exiting the fuel flow equalizer 202. Also, the maximum velocity of the flow of fuel 102 may be reduced immediately after or near the burner nozzle 104. Therefore, the velocity of the flow of fuel 102 in zones V_2a and V_3a may be lower than flow velocity in the zones V₂ and V₃ (FIGS. 1A and 1B), respectively.

FIG. 2B illustrates combustion of the fuel that passed through the fuel flow equalizer 202 according to an embodiment. The fuel that exits the burner nozzle 104 is ignited, and the combusted fuel forms a flame 208. In particular, reduced and/or equalized fuel flow velocities (after passing through the fuel flow equalizer 202) may produce a wider and shorter flame 208 (as compared with the flame 108 (FIG. 1B) produced without the fuel flow equalizer 202. As such, the flame 208 may have greater stability than the flame 108 (FIG. 1B).

Generally, the fuel flow equalizer 202 may be made of any suitable materials, which may include heat and/or corrosion resistant metallic materials. For instance, the fuel may burn or combust at temperatures in excess of about 2,800° F. Accordingly, in some embodiments, the fuel flow equalizer 202 may include materials that may withstand temperatures of at least about 2,800° F. More specifically, embodiments may include refractory metals, such as molybdenum, tungsten, niobium, tantalum, rhenium, alloys of the foregoing, ceramic materials, combinations thereof, or other suitable materials.

It should be also appreciated that the fuel flow equalizer 202 may include other metals and/or materials. For example, the fuel flow equalizer 202 may include graphite. The fuel flow equalizer 202 also may include sintered materials, such as sintered refractory metal materials. The sintered refractory metal materials may exhibit a melting temperature or temperature range (e.g., a solidus temperature or a liquidus temperature) of about 1600° C., about 1800° C., about 2000° C., about 2200° C., 2400° C., 2600° C., 2800° C., 3000° C., 3000° C., or about 3200° C. In other embodiments, the sintered refractory metal materials may exhibit a melting temperature or temperature range between about 1600° C. and about 3500° C.; about 1800° C. and about 3200° C.; about 2000° C. and about 3000° C.; or about 2300° C. and about 2800° C. Also, the sintered refractory metal materials may exhibit higher or lower melting temperatures or temperature ranges.

As described below in more detail, the fuel flow equalizer 202 may have various shapes and sizes, which may vary from one embodiment to the next. The particular shape and size of the fuel flow equalizer 202 may depend on the shape and/or size of the combustion space, burner nozzle, position and/or orientation of the fuel flow equalizer 202 relative nozzle and/or within the fuel flow, among others. In some embodiments, the fuel flow equalizer 202 may include a mesh, a honeycomb, or a pattern of alternating opens spaces or openings and barrier elements. As described below, the pattern of openings in the fuel flow equalizer 202 may vary from one embodiment to another.

Also, in some embodiment, a single fuel flow equalizer 202 may be placed downstream from the burner nozzle 104. Alternatively, a plurality of fuel flow equalizers may be placed downstream from the burner nozzle 104. In one or more embodiments, the plurality of fuel flow equalizers that may be placed downstream from the burner nozzle 104 may have the same orientation and/or the same mesh or patterns as one another (e.g., the opening in the mesh of the multiple fuel flow equalizers may be approximate aligned with one another). For example, the plurality of fuel flow equalizers may be arranged in series with each other. In additional or alternative embodiments, at least some of the fuel flow equalizers may be oriented in a manner that misaligns openings in the mesh of one fuel flow equalizer with another fuel flow equalizer. Furthermore, one, some, or all of the fuel flow equalizers may be the same. Alternatively, at least one fuel flow equalizer may be different from at least one other fuel flow equalizer.

In an embodiment illustrated in FIG. 3A the fuel flow equalizer 202a may have an approximately circular or cylindrical peripheral shape. Except as otherwise described herein, the fuel flow equalizer 202a and its materials, elements, and components may be similar to or the same as the fuel flow equalizer 202 (FIGS. 2A and 2B) and its corresponding materials, elements, and components. In an embodiment, the fuel flow equalizer 202a may include a plurality of rib members 204a that may form a mesh that includes multiple flow openings 206a.

In some embodiments, the rib members 204a may be interconnected (i.e., connected or coupled together) to form the flow openings 206a. For instance, at least some of the rib members may be mechanically connected together (e.g., riveted, press-fit, folded one over another, may include slits that slide over portions of the rib members 204a, etc.). Alternatively, the rib members 204a may be bonded together or integrated (i.e., integrally formed) with one another. Examples of suitable bonding may include brazing, welding (including spot welding), etc. In any event, the fuel and/or oxidizer may pass through the flow openings 206a, as the fuel moves downstream from the nozzle. Moreover, as described above, the flow velocity of the fuel may be reduced and may become more uniform after the fuel passes through the fuel flow equalizer 202a.

The rib members 204a may have a suitable thickness and height. Furthermore, in some examples, the height of the rib members 204a may define the thickness of the fuel flow equalizer 202a. Likewise, the height of the rib members 204a may define a length of the flow openings 206a (i.e., the length of the path for the fuel flow between entrance into the flow openings 206a and exit therefrom). Accordingly, in some embodiments, to increase the length of the flow openings 206a, the thickness of the rib members 204 may be increased. Conversely, to decrease the length of the flow openings 206a, the thickness of the rib members 204a may be decreased.

In some embodiments, the perimeter or periphery of the fuel flow equalizer 202a may be unbound or unenclosed and may be formed by the rib members 204a. For example, at least some ends or portions of the rib members 204a may be exposed at and/or about the periphery of the fuel flow equalizer 202a. Alternatively, the periphery of the fuel flow equalizer 202a may be enclosed (e.g., by a band), such that the ends of the rib members 204a are not exposed about the periphery of the fuel flow equalizer 202a. For example, the fuel flow equalizer 202a may have a relatively smooth surface that defines the periphery thereof.

In additional or alternative embodiments, the fuel flow equalizer may have non-circular or non-cylindrical shapes. FIG. 3B, for example, illustrates a fuel flow equalizer 202b that has an approximately rectangular shape according to an embodiment. Except as otherwise described herein, the fuel flow equalizer 202b and its materials, elements, and components may be similar to or the same as any of the fuel flow equalizers 202, 202a (FIGS. 2A-3A) and their corresponding materials, elements, and components. For example, the fuel flow equalizer 202b may include a mesh or pattern of openings and rib members that may be similar to or the same as the pattern of the fuel flow equalizer 202a (FIG. 3A).

In some embodiments, the rectangular shape of the fuel flow equalizer 202b may facilitate coverage of multiple burner nozzles, which may be disposed along the length of the fuel flow equalizer 202b. In other words, the fuel from multiple burner nozzles may flow downstream through a single fuel flow equalizer 202b. It should be appreciated, however, that any of the fuel flow equalizers described herein may be positioned downstream from a single or multiple burner nozzles to equalize fuel and/or oxidizer flow therefrom.

Furthermore, additional or alternative embodiments include a square fuel flow equalizer 202c, shown in FIG. 3C. Except as otherwise described herein, the fuel flow equalizer 202c and its materials, elements, and components may be similar to or the same as any of the fuel flow equalizers 202, 202a, 202b (FIGS. 2A-3B) and their corresponding materials, elements, and components. Other embodiments may include fuel flow equalizer that may have a non-rectangular or non-square shape (e.g., polygonal, hexagonal, irregular shaped, etc.). In any event, one or more fuel flow equalizers may be placed downstream from one or more burner nozzles, and the fuel flow equalizers may have suitable shapes and sizes to equalize fuel flow and/or reduce fuel flow velocity.

As mentioned above, the fuel flow equalizer may have any number of suitable patterns of openings and rib members that separate the openings one from another. For example, FIG. 3D illustrates a fuel flow equalizer 202d that includes a suitable pattern according to an embodiment. Except as otherwise described herein, the fuel flow equalizer 202d and its materials, elements, and components may be similar to or the same as any of the fuel flow equalizers 202, 202a, 202b, 202c (FIGS. 2A-3C) and their corresponding materials, elements, and components.

As described above, in some embodiments, the fuel flow equalizer 202d may include a band 208d that may at least partially surround the mesh or grid pattern formed by rib members 204d, 204d′ and flow openings 206d, 206d′. More specifically, the band 208d may enclose otherwise unbound ends of the rib members 204d and/or rib members 204d′. The band 208d may form or define a peripheral surface of the fuel flow equalizer 202d (e.g., the peripheral surface may be substantially continuous, smooth, ribbed, etc., as may be formed by the surface of the band). Generally, the band 208d may have the same approximate peripheral shape as the shape formed by unbounded rib members 204d and/or rib members 204d′. Alternatively, the shape formed by the band 208d may be different from the shape formed by the unbounded rib members 204d and/or rib members 204d′ (e.g., the 208d may have a non-uniform thickness about the periphery thereof).

The band 208d also may provide additional structural support and/or rigidity to the rib members 204d, 204d′. For instance, the band 208d may facilitate securing the fuel flow equalizer 202d downstream from the nozzle. In some embodiments, the band 208d may include similar or the same material as the rib members 204d, 204d′. In additional or alternative embodiments, material of the band 208d may be different from the material of the rib members 204d, 204d′. In any case, the band 208 may have sufficient rigidity and/or heat resistance.

In some embodiments, the fuel flow equalizer 202d may include a mesh formed by multiple rib members 204d and rib members 204d′, which may define multiple flow openings 206d, 206d′. For example, the flow openings 206d may have an elongated hexagonal shape. In particular, in one embodiment, four angled sides of the hexagonal opening flow openings 206d may be longer than two opposing sides of the flow openings 206d. In other words, four of the rib members 204d that define the flow openings 206d may be long rib members 204d, while two sides of the flow openings 206d may be defined by short rib members 204d′.

Furthermore, in at least one embodiment, the flow openings 206d′ may have a parallelogram shape. For example, two sides of the flow openings 206d′ may be defined by long rib members 204d and two sides may be defined by short rib members 204d′. Additionally, at least some of the flow openings 206d′ may share one or more of the rib members 204d and/or rib members 204d′ with the flow openings 206d. For instance, the same rib members 204d that define two long sides of the flow openings 206d′ may partially define long sides of two flow openings 206d, which may be adjacent to and on opposite sides of the flow openings 206d′.

Similarly, the same rib members 204d′ that define the two short sides of the flow openings 206d′ may partially define short sides of two flow openings 206d, which may be adjacent to and on opposite sides of the flow openings 206d′. Hence, in some embodiments, the flow openings 206d′ may be adjacent to one, two, three, or four of the flow openings 206d (e.g., the flow opening 206d′ may be surrounded by four flow openings 206d on all sides of the flow opening 206d′). Moreover, it should be appreciated that the area of the flow openings 206d may be greater than the area of the flow openings 206d′.

Also, the flow openings may be defined by any number of rib members, which may have any suitable length as well as length ratio one to another (e.g., rectangular flow openings may have any suitable length to width ratio). In some embodiments, the flow openings may be hexagonal with all sides having approximately the same length. Accordingly, embodiments may include flow openings that may have any suitable polygonal shape. Moreover, embodiments also may include openings that have circular, semicircular, or irregular shapes. FIG. 3E, for example, illustrates a fuel flow equalizer 202e that has approximately oval flow openings 206e defined by one or more rib members 204e according to an embodiment. Except as otherwise described herein, the fuel flow equalizer 202e and its materials, elements, and components may be similar to or the same as any of the fuel flow equalizers 202, 202a, 202b, 202c, 202d (FIGS. 2A-3D) and their corresponding materials, elements, and components.

For example, the oval flow openings 206e may be placed adjacent one another in a manner that defines additional openings flow openings 206e′, which may be located between four flow openings 206e that surround the flow openings 206e′. In other words, portions of the rib members 204e that define four flow openings 206e also may define the flow openings 206e′ that may be located between the four flow openings 206e. In additional or alternative embodiments, as mentioned above, the flow openings may be circular. Similarly, however, the rib members that define circular openings may define additional openings between the circular openings.

Embodiments also may include rectangular openings that may be aligned with one another and form multiple rows and/or columns. FIG. 3F, for instance, illustrates a fuel flow equalizer 202f that include rectangular flow openings 206f formed by multiple rib members 204f according to an embodiment. Except as otherwise described herein, the fuel flow equalizer 202f and its materials, elements, and components may be similar to or the same as any of the fuel flow equalizers 202, 202a, 202b, 202c, 202d, 202e (FIGS. 2A-3E) and their corresponding materials, elements, and components.

Also, the rib members 204f may overlap one another. For example, the rib members 204f may span or extend between outermost edges of the fuel flow equalizer 202f. Moreover, the rib members 204f may include slits that may pass through a portion of the height of the rib members 204f (e.g., half-way through the height). Such slits on the rib members 204f, which oriented perpendicularly to one another, may be aligned in a manner that a slit of one rib member 204f enters into the slit in another rib member 204f and vice versa. In other words, the rib members 204f may overlap and connect to one another via multiple slits therein.

It should be appreciated that In addition, the fuel flow equalizer may include other suitable patterns of flow openings and rib members and the patterns disclosed herein should not be considered as an exhaustive list nor limiting the present disclosure. In general, the fuel flow equalizer patterns can exhibit dimensions according to desired fuel flow velocity distribution characteristics and system design.

As described above, the fuel and/or flame also may encounter and may be influenced by a flame anchoring apparatus, which may control the shape and/or position of the flame. For example, FIG. 4 shows a combustion system 300 that may include a flame anchoring apparatus 302 located downstream from the burner nozzle 104 according to an embodiment. Except as otherwise described herein, the fuel flow equalizer 202g and its materials, elements, and components may be similar to or the same as any of the fuel flow equalizers 202, 202a, 202b, 202c, 202d, 202e, 202f (FIGS. 2A-3F) and their corresponding materials, elements, and components.

In some embodiments, the flame anchoring apparatus 302 may be located downstream (or after) a fuel flow equalizer 202g. Accordingly, a substantially equalized fuel flow and/or a flame formed therefrom may encounter the flame anchoring apparatus 302. In some embodiments, the flame anchoring apparatus 302 may be configured as an electrically conductive bluff body or an electrically conductive toric body (e.g., an annulus or other type of body having a passageway through which fuel flow from passing through the fuel flow equalizer 202g may flow).

In some embodiments, the fuel flow equalizer 202g and the flame anchoring apparatus 302 may be integrated (e.g., the fuel flow equalizer 202g may be configured to anchor the flame thereto and/or may be integrally formed together with the flame anchoring apparatus 302). Additionally or alternatively, the fuel flow equalizer 202g and flame anchoring apparatus 302 may be connected or coupled to one another. In any event, in at least one embodiment, the flame anchoring apparatus 302 may receive equalized fuel flow or the flame formed from such flow. For instance, the fuel and/or oxidizer may pass through and exit the fuel flow equalizer 202g before encountering the flame anchoring apparatus 302.

Generally, the flame anchoring apparatus 302 may control shape and/or position of a charged flame 308. For example, the charged flame 308 may be charged by injecting charge into the fuel and/or the flame. By injecting charge with a charger 310, the fuel, flame, or combinations thereof acquires a net electrical charge (e.g., a net positive or negative charge). In an embodiment, the charger 310 may include a corona electrode (e.g., a sharpened electrode or saw blade) configured to generate ions that are injected into the fuel, flame, or combinations thereof to impart the net electrical charge. A voltage power supply 304 (e.g., a high voltage power supply) biases the charger 310 to cause charges to be emitted from the charger 310. The flame anchoring apparatus 302 is also electrically coupled to the voltage power supply 304 and biases the flame anchoring apparatus 302 oppositely to the bias of the charged flame 308 to electrodynamically attract the charged flame 308 to the flame anchoring apparatus 302. For example, application of the bias to the flame anchoring apparatus 302 may control the position and/or shape of the charged flame 308. More specifically, the voltage power supply 304 and the anchoring apparatus 302 may generate an electric field near one or more surfaces or sides of the flame anchoring apparatus 302, which may attract, couple, and/or anchor the charged flame 308 to at least one side of the anchoring apparatus 302.

The fuel flow equalizer 202g may assist on maintaining the charged flame 308 attached to the flame anchoring apparatus 302. The charged flame 308 may tend to move around the desired position above or below the flame anchoring apparatus 302, thus being more stably anchored (as compared to the combustion without the flame anchoring apparatus 302). The fuel flow equalizer 202g may be positioned between the burner nozzle 104 and the flame anchoring apparatus 302 to allow a more uniform fuel flow velocity distribution that may contribute to more efficient flame stabilization around the flame anchoring apparatus 302.

Generally, the flame anchoring apparatus 302 may include any suitable material that may be electrically conductive. As such, the voltage power supply 304 and the flame anchoring apparatus 302 may produce an electric field near the flame anchoring apparatus 302, which may be controlled by the voltage power supply 304 in a manner that controls the charged flame 308. Moreover, in some embodiments, the combustion system 300 may include one or more sensors, which may determine direction of current flow to or from the flame anchoring apparatus 302. Accordingly, the voltage power supply 304 and the sensors may provide spark management and detection in of flashback event and/or other operational failures.

As noted above, the fuel flow equalizer 202g may equalize and/or reduce the fuel flow velocity. Accordingly, in some embodiments, the fuel flow equalizer 202g can enable or facilitate the flame anchoring apparatus 302 to operate at a higher rate of fuel throughput. In other words, the fuel flow equalizer 202g may increase operating efficiency of the combustion system 300 (as compared with an electrodynamic flame control system that does not include the fuel flow equalizer 202g).

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

Claims

1. A combustion system, comprising:

at least one burner nozzle configured to discharge fuel into a combustion space sized and configured to at least partially contain a flame produced during combustion of the fuel and an oxidizer;

at least one fuel flow equalizer positioned downstream from the at least one burner nozzle, the fuel flow equalizer including a plurality of openings sized and configured to allow the fuel to pass therethrough;

a flame anchoring apparatus positioned downstream from the at least one fuel flow equalizer; and

a voltage power supply electrically coupled to the flame anchoring apparatus, the voltage power supply being configured to bias the flame anchoring apparatus so that the flame is attracted to the flame anchoring apparatus.

2. The combustion system of claim 1, wherein the flame anchoring apparatus include an electrically bluff body.

3. The combustion system of claim 1, wherein the flame anchoring apparatus and the at least one fuel flow equalizer are integral with each other.

4. The combustion system of claim 1, wherein some openings of the plurality of openings are larger than other openings of the plurality of openings.

5. The combustion system of claim 1, wherein the plurality of openings includes first openings and second openings, and the first openings have one or more of a different shape or size than the second openings.

6. The combustion system of claim 1, wherein at least some openings of the plurality of openings of the at least one fuel flow equalizer have an approximately hexagonal shape.

7. The combustion system of claim 1, wherein at least some openings of the plurality of openings of the at least one fuel flow equalizer have one or more of an approximately rectangular shape, a parallelogram shape, a round shape, or an oval shape.

8. The combustion system of claim 1, wherein the voltage power supply and the flame anchoring apparatus produce an electric field near at least one surface of the flame anchoring apparatus when the flame anchoring apparatus is biased by the voltage power supply.

9. A method for stabilizing a flame within a combustion space, the method comprising:

discharging fuel from at least one nozzle into a combustion space;

passing the fuel through at least one fuel flow equalizer structure positioned downstream from the nozzle;

igniting the fuel and an oxidizer to produce a flame;

applying an electrical potential to a flame anchoring apparatus effective to anchor the flame to the flame anchoring apparatus.

10. The method of claim 9, wherein the at least one fuel flow equalizer includes a structure having a plurality of openings separated by a plurality of rib members.

11. The method of claim 10, wherein the at least one fuel flow equalizer is oriented generally perpendicular to the nozzle.

12. The method of claim 9, wherein the flame anchoring apparatus includes an electrically conductive bluff body.

13. The method of claim 9, wherein the flame anchoring apparatus is positioned in the stream of flow of the mixture of fuel and air.

14. The method of claim 9, wherein passing the fuel through the at least one fuel flow equalizer structure positioned downstream from the at least one nozzle occurs before applying the electrical potential to the flame anchoring apparatus.

15. The method of claim 9, wherein passing the fuel through the at least one fuel flow equalizer structure positioned downstream from the at least one nozzle includes:

passing at least some of the fuel through first openings in the at least one fuel flow equalizer; and

passing at least some of the fuel through second openings in the at least one fuel flow equalizer, wherein the first openings have one or more of a different size or different shape than the second openings.

16. A flame control system, comprising:

at least one burner nozzle configured to discharge fuel into a combustion space sized and configured to at least partially contain a flame produced during combustion of the fuel and an oxidizer;

at least one fuel flow equalizer disposed downstream from the burner nozzle, the fuel flow equalizer including a plurality of openings sized and configured to allow the fuel to pass therethrough;

a flame anchoring apparatus positioned downstream from the at least one fuel flow equalizer so that the fuel exiting the at least one fuel flow equalizer encounters the flame anchoring apparatus;

a charger configured to charge at least one of the flame or the fuel to form a charged flame; and

a voltage power supply electrically coupled to the flame anchoring apparatus and configured to apply an electrical potential thereto that attracts the charged flame to the flame anchoring apparatus.

17. The flame control system of claim 16, wherein the flame anchoring apparatus includes an electrically conductive body.

18. The flame control system of claim 16, wherein the at least one fuel flow equalizer is generally perpendicular to the burner nozzle.

19. The flame control system of claim 16, wherein the plurality of openings are defined by a plurality of interconnected rib members.

20. The flame control system of claim 19 wherein the rib members include one or more of molybdenum, tungsten, niobium, tantalum, rhenium, alloys of thereof, or graphite.