FLASHBACK RESISTANT BURNER

FIELD

The present disclosure is directed to fuel gas burners and more particularly to fuel gas burners for use with hydrogen.

BACKGROUND

Currently, heat is generated in many industries from combustion processes that utilize polluting and toxic fuels, for example natural gas contains carcinogenic compounds, is a greenhouse gas and creates combustion products that are also toxic and greenhouse gases (e.g., CO, CO₂). The result of combustion of these fuels can have detrimental effects. For example, carbon monoxide is a poisonous gas, and CO₂has negative environmental impacts. Improved heating solutions are desired.

Hydrogen is a non-toxic and non-polluting fuel and t primary product of combustion of pure hydrogen is water. These properties make hydrogen an ideal fuel for applications where human health and environmental impacts are a priority. Some examples of these applications include—but are not limited to—cooking food, indoor space heating, and indoor water heating.

An additional benefit of hydrogen as a fuel is its extreme buoyancy. Fuels are combustive by nature and thus pose the threat of uncontrolled ignition when released unintentionally and concentrated. Hydrogen is about 14.4 times lighter than air and will rapidly disperse when released into the atmosphere. This is not the case for conventional fuels such as propane and butane, which are heavier than air, or natural gas which is only about 1.8-times lighter than air. Thus, a hydrogen burner can be considerably safer than a propane, butane, or natural gas burner because hydrogen will disperse rapidly.

However, burners for conventional hydrocarbon fuel gases such as propane, methane, natural gas, propylene, and the like are unsuitable for use with hydrogen because hydrogen has a very high flame speed relative to conventional fuels. Burners for conventional fuels mix an oxidant such as oxygen or air with the fuel inside an enclosed volume of the burner before expelling the fuel/oxidant mixture from one or more apertures for combustion. Due to the high flame speed of hydrogen, it is prone to flashback, which means the flame can propagate backward against the flow of the fuel gas into the enclosed volume of the burner and detonate. Thus, the practice of premixing air and fuel prior to combustion as is often used with conventional fuels is not suitable when hydrogen is the fuel. Improved burner designs are therefore desired.

SUMMARY

A burner comprising: wall configured to contain a fuel gas within an enclosed volume of the burner: a plurality of apertures formed in the wall: and a plurality of actuators each operatively associated with one of the plurality of apertures and configured to be selectively activated to establish or sever fluid communication between an atmosphere surrounding the burner and the enclosed volume, through the respective apertures. The plurality of apertures are configured to prevent flashback of the fuel gas into the enclosed volume.

Optionally, in some embodiments the plurality of apertures have an effective diameter smaller than a quenching distance of the fuel gas.

Optionally, in some embodiments the fluid communication is configured to provide a flow of the fuel gas suitable to support a flame.

Optionally, in some embodiments a flame is established adjacent to a respective aperture responsive to the activation of a respective actuator.

Optionally, in some embodiments the plurality of actuators comprises at least one of a solenoid, a motor, a solenoid, a dashpot, a servo, a power screw, a resilient member, or a stepper motor.

Optionally, in some embodiments the burner is configured to form a user-defined pattern with one or more flames formed at one or more of the plurality of apertures responsive to the selective opening of the plurality of apertures by the respective plurality of actuators.

Optionally, in some embodiments the burner further includes an igniter. The burner is configured to carry a flame from a pilot aperture adjacent to the igniter to a pattern location via the selective actuation of one or more of the plurality of actuators.

Optionally, in some embodiments a system includes a burner, a cooking apparatus housing the burner and a controller in electrical communication with the plurality of actuators and configured to selectively open and close the plurality of apertures via selective activation of the plurality of actuators.

Optionally, in some embodiments the system includes a user device in electrical communication with the controller and configured to communicate the user-defined pattern to the controller.

Optionally, in some embodiments, the system includes a plurality of deflectors each disposed adjacent to one of the plurality of apertures, wherein each of the plurality of deflectors imparts a thrust when a flame is formed adjacent to the respective aperture. Optionally, in some embodiments the thrust rotates the burner.

Optionally, in some embodiments the wall has a toroidal shape.

Optionally, in some embodiments each aperture of the plurality of apertures is spaced apart from another of the plurality of apertures such that the flame located at a first aperture of the plurality of apertures can propagate to a second aperture of the plurality of apertures.

Optionally, in some embodiments, the system includes: a fuel gas source: a conduit in fluid communication with the fuel gas source: and a flow restrictor disposed at least partially within the conduit and configured to restrict a flow of the fuel gas from the fuel gas source to the burner.

Optionally, in some embodiments, the apertures of the plurality of apertures are about 0.4 mm in diameter.

Optionally, in some embodiments, the fuel gas is hydrogen.

Optionally, in some embodiments, the fuel gas is not mixed with an oxidant in the enclosed volume.

Optionally, in some embodiments, a pressure of the fuel gas within the enclosed volume is higher than a pressure of the atmosphere such that the oxidant does not infiltrate into the enclosed volume.

In some embodiments, a method of patterning a food item includes receiving a user-defined pattern: providing a fuel gas to a burner. The burner includes a wall configured to contain a fuel gas within an enclosed volume of the burner, a plurality of apertures are formed in the wall, and a plurality of actuators each operatively associated with one of the plurality of apertures and configured to be selectively activated to establish fluid communication between an atmosphere surrounding the burner and the enclosed volume, through the respective apertures, the plurality of apertures are configured support respective flames adjacent thereto, and the respective flames are arranged in the user-defined pattern proximate to the food item.

Optionally, in some embodiments, the aperture has an effective diameter smaller than a quenching distance of the fuel gas, and igniting the fuel gas in the surrounding environment.

Optionally, in some embodiments, each aperture of the plurality of apertures is spaced apart from another of the plurality of apertures such that the flame located at a first aperture of the plurality of apertures can propagate to a second aperture of the plurality of apertures.

In some embodiments, a system includes a power supply configured to receive electrical power from an alternating current source: an electrolyzer in electrical communication with the power supply and configured to generate hydrogen gas responsive to receiving electrical power from the power supply: a vessel configured to store the hydrogen gas: a burner including a plurality of apertures formed therein. The apertures provide fluid communication from the enclosed volume to an environment surrounding the burner, the plurality of apertures are configured to prevent flashback of the fuel gas into the enclosed volume.

Optionally, in some embodiments, the plurality of apertures have an effective diameter smaller than a quenching distance of the fuel gas.

Optionally, in some embodiments, a maximum rate of electrical power provided to the power supply is less than a maximum heat rate of the burner.

In some embodiments, a system includes: a burner: an electrical power supply: an electrolyzer configured to receive electrical power from the power supply at an electrical power input rate, and generate hydrogen gas responsive to the receipt of the electrical power: and a storage device configured to store the hydrogen gas. The storage device is configured to supply hydrogen gas to the burner at a heat rate greater than the electrical power input rate, and the burner is configured to burn the hydrogen gas at the heat rate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a simplified block diagram of an example of a burner system for use with a burner disclosed herein.

FIG. 1B is a simplified block diagram of an example of a burner system for use with a burner disclosed herein.

FIG. 1C is a simplified block diagram of an example of a burner system for use with a burner disclosed herein.

FIG. 1D is a simplified block diagram of an example of a burner system for use with a burner disclosed herein.

FIG. 1E is a simplified block diagram of an example of a burner system for use with a burner disclosed herein.

FIG. 2A is an isometric view of an embodiment of a burner.

FIG. 2B is a side elevation view of the burner of FIG. 2A.

FIG. 2C is an end elevation view of the burner of FIG. 2A.

FIG. 3A is an isometric view of a burner.

FIG. 3B is a side elevation view of the burner of FIG. 3A.

FIG. 3C is an end elevation view of the burner of FIG. 3A.

FIG. 4A is a simplified isometric view of a burner.

FIG. 4B is a simplified bottom view of the burner of FIG. 4A.

FIG. 4C is a section view of the burner of FIG. 4B taken along section line 4C-4C of FIG. 4B.

FIG. 5A is a top plan view of a burner.

FIG. 5B is a section view of the burner of FIG. 5A taken along section line 5B-5B of FIG. 5A, in a first configuration.

FIG. 5C is a section line of the burner of FIG. 5A taken along section line 5B-5B of FIG. 5A in a second configuration.

FIG. 5D is a section view of the burner of FIG. 5A taken along section line 5B-5B of FIG. 5A in a third configuration at a first time.

FIG. 5E is a section view of the burner of FIG. 5A taken along section line 5B-5B of FIG. 5A in a fourth configuration at a second time later than the first time.

FIG. 5F is a section view of the burner of FIG. 5A taken along section line 5B-5B of FIG. 5A in a fifth configuration at a third time later than the second time.

FIG. 5G is a section view of the burner of FIG. 5A taken along section line 5B-5B of FIG. 5A in a sixth configuration at a fourth time later than the third time.

FIG. 5H is a top plan view of the burner of FIG. 5A in a third configuration.

FIG. 5I is a top plan view of the burner of FIG. 5A, with a food item.

FIG. 5J is a bottom isometric view of the food item of FIG. 5E with a cooking pattern.

FIG. 6A is a simplified isometric view of a cooking apparatus including the burner of FIG. 5A.

FIG. 6B is a detailed view of an igniter taken at line 6B-6B of FIG. 6A.

FIG. 7A is a portion of a method of designing a burner of the present disclosure.

FIG. 7B is a portion of the method of designing a burner of FIG. 7A.

FIG. 8 is a simplified block diagram of components of a controller or user device.

DETAILED DESCRIPTION

The burner disclosed herein is a device that controls and facilitates combustion of a flammable gas (e.g., hydrogen) into a usable heat source for many applications. Some example applications are cooking stoves, barbecues, furnaces, space heaters, process heaters, sources of visible light/infrared/ultraviolet radiation, and decorative fire displays. In one embodiment, hydrogen gas is supplied from a gas source 100. The hydrogen can be directed to a combustion area via an arrangement of tubing, conduit, and optionally one or more valves or other instrumentation such as a filter 104, needle valve 106, flow restrictor or orifice 108, pressure regulator 116, shutoff valve 118, or pressure sensor 120. In the combustion area there may be one or more burners 101 where the hydrogen is ignited and produces a flame.

Fuel Gas Source 100

The hydrogen fuel gas source 110 for burner embodiments disclosed herein may be, but is not limited to, a compressed gas container, electrolyzer, vaporizer from a liquid hydrogen storage tank, metal hydride storage container, or a device that generates hydrogen from a separate process such as reformation processes, biological process, ammonia cracking, or other chemical process, or any combination thereof. The heat produced by the burner may be used as an energy source that works symbiotically with the fuel gas source 110, e.g., a heat source for a metal hydride hydrogen storage that heats the storage to liberate more hydrogen gas. When used with an electrolyzer, the burner enables the generation of a fire or flame where only electricity is otherwise available. This is a unique advantage over conventional fuels that can be unavailable in certain locations, dwellings, or buildings due to regulatory requirements and/or lack of infrastructure.

As shown for example in FIG. 1E, in some embodiments, the fuel gas source 110 may include a power supply 126 that generates power (e.g., via one or more batteries) or receives alternating current from a grid power source 128. In some examples, such as when the power is alternating current (“AC”) power, the AC power may be converted to direct current (“DC”) power e.g., for use by an electrolyzer 122. The electrolyzer 122 may generate hydrogen gas responsive to the receipt of electrical power from the power supply 126. For example, the electrolyzer 122 may catalytically split water molecules into hydrogen and oxygen gases. The hydrogen and oxygen gases may be formed on separate electrodes of one or more electrochemical cells of the electrolyzer 122 and collected for use in a burner. In some embodiments, the oxygen gas may be vented to atmosphere. The fuel gas source 110 may optionally include a pressure vessel 124 and/or compressor 130 suitable to store the generated hydrogen gas at an elevated pressure such as 50 bar, 100 bar, 250 bar, 350 bar, 700 bar, or higher. For example, the fuel gas source 110 may be charged with hydrogen gas in times where the burner is not in use. The energy stored in the fuel gas source 110 may supply power to a burner when desired. The inclusion of the pressure vessel and/or compressor 130 allows the fuel gas source 110 to provide a burner with a heat rate substantially greater than an electrical supply rate to the power supply 126. For example, a typical 115-V 15-amp household circuit may provide a maximum of about 1800-2000 Watts of electrical power. Meanwhile, a typical natural gas or propane powered grill may have a heat rate of about 55,000 BTU/hr (approximately equivalent to 16 KW). Thus, it is not possible to simply provide resistive heating with a 15-amp circuit equivalent to a typical natural gas barbecue grill. In this manner, the fuel gas source 110 described can beneficially provide flame-based cooking and an appropriate heat rate similar to that of a hydrocarbon-powered grill but without the need to replace tanks, run a dedicated natural gas line, or use an expensive 220-V or 3-phase electrical service. Furthermore, flame-based cooking has many benefits over electrical heating, such as the near instant provision of a flame as opposed to the slow heating of an electrical element, better quick adjustment of heat, and the like. Flame-based cooking using hydrogen, as with the burners disclosed herein has numerous benefits over hydrocarbon-based flame cooking, such as no generation of poisonous CO or the greenhouse gas CO2, a more controllable and direct flame, and the provision of flame-based cooking in areas where hydrocarbons fuels are expensive or not readily available.

Burners

The heat from combustion of the flammable gas is distributed utilizing one or more burners, e.g., a burner 102, burner 202, burner 302, burner 402, and/or burner 502. The burners can have one or more walls 204 that form an enclosed volume 206 containing the flammable gas. The walls 204 may be in the form of a plate or tube, have a circular, spherical, rectangular, toroidal, or other cross-sectional shape, and can be laid out as straight, bent, circular, spiral, or other pattern. For example, in the accompanying figures the burners 202 and 302 are shown in one embodiment, as a straight tube configuration. The burner 402 is toroidal in shape, whereas as the burner 502 is planar in shape. The shape, size, and configuration of the burners can be varied based on the desired heat or energy output for the burner, e.g., a burner for use in a commercial kitchen may be substantially larger than one configured for use in a residential apartment.

The burners disclosed herein have one or more apertures 112 that penetrate through the wall 204 thereof. In some embodiments, nozzles may be coupled, e.g., removably coupled, to the wall to enable the placement apertures of differing sizes. Such replaceable nozzles may have the benefit of enabling customization of the heating rate of a burner without replacing the entire burner. The enclosed volume 206 contains the fuel gas, and the fuel gas is combusted as a flame as it exits each aperture 112 and mixes with air or another oxidant. The burners of the present disclosure are designed to ignite a fuel gas such as hydrogen without pre-mixing the fuel and air, and while also preventing flashback. For example, the burners of the present disclosure may comprise a closed system from the fuel gas source 110 to just outside the apertures 112, thereby preventing the introduction of an oxidant such as air into the fuel gas until the fuel gas leaves the apertures. Furthermore, the burners of the present disclosure may have a fuel gas pressure within the conduits 114 and/or internal volume 206 greater than the surrounding atmospheric pressure, thereby reducing or preventing the infiltration of air into the burner. Burners of the present disclosure enable the fuel gas to mix with an oxidant outside of the burner, after the fuel gas passes through one or more apertures 112. to support combustion. However, the burners prevent the mixing of the fuel gas with an oxidant in the burner, preventing or reducing flashback, inadvertent ignition, and/or early ignition and enabling the use of the burner with fuel gases such as hydrogen with high flame speeds. Thus, the burners of the present disclosure address the deficiencies of conventional burners. Even when not designed for premixed combustion, a burner that is used intermittently, such as in a heater, stove, barbecue, or display fire, may be exposed to ambient air which can diffuse into the burner during periods of non-use leading to a fuel air mixture within the burner. When hydrogen is used as the fuel with a traditional burner, the next time the burner ignites following a previous ignition, the flame can propagate back into the burner and cause detonation. Flame arrestors are commonly used to prevent flashback for large openings. However, flame arrestors are not practical for the many small apertures needed for an effective burner.

To address the problems of conventional fuel burners that would prevent use with hydrogen as a fuel source, the burners of the present disclosure include one or more apertures 112 sized to have an effective diameter less than the quenching distance of the fuel/flame (e.g., a hydrogen flame). A hydrogen flame cannot propagate through an aperture of the disclosed burner where the effective diameter is smaller than the quenching distance. The quenching distance is a function of combustion flame speed and heat transfer characteristics, which in turn depend primarily upon gas composition, equivalence ratio, and upstream (unburned gas) pressure and temperature. The quenching distance can be found from experimental data, empirical equations, or analytical equations. One example is shown in Eq. 1 below for the quenching distance (d) of a hydrogen flame:

$\begin{matrix} d = 5.4 \sqrt{e β} α / S_{L} & (Eq . 1) \end{matrix}$

Where e is the base of the natural logarithm. approximately is 2.718, β is a non-dimensional activation energy parameter (which depends upon temperature and reaction characteristics), α is the thermal diffusivity, and S_Lis the laminar burning velocity.

For example, a stoichiometric mixture of hydrogen and air at 300 K and atmospheric pressure has a quenching distance of about 0.8 mm. This quenching distance decreases to about 0.4 mm when the upstream pressure reaches 2.5 atm. See, for example, the embodiments of FIG. 2A through FIG. 3C where the apertures are approximately 0. 4mm in diameter. In some examples, the apertures 112 may be about 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm or 0.8 mm. Typically, the quenching distances are smallest when the mixture is stoichiometric. In comparison, the apertures in a typical propane burner are about 3 mm in diameter and could cause a hazardous situation if used for hydrogen because they would not prevent flashback. On the contrary, the apertures in the burners of the present disclosure are sized specifically to prevent flashback of hydrogen by having an effective diameter less than the quenching distance of hydrogen for the application, as determined by the applicant through analytical and experimental methods corresponding to the physical conditions of the application.

With reference to FIG. 4A-FIG. 4C, a burner 402 is disclosed. The burner 402 includes a toroidal-shaped wall 204. The burner 402 may have a wall 204 formed in other shapes such as a square, oval, disc, etc. The wall 204 may be supported by one or more conduits 114 that distribute the fuel gas source to the volume 206 formed by the wall 204. The conduits 114 may also support the wall 204. With reference to FIG. 4C, for example, one or more conduits 114 may be arranged in a planar fashion within a toroidal ring formed by the wall 204. The conduits 114 may be in fluid communication with one another and/or with the volume 206 of the burner 402. The conduits 114 may be supported by a substantially vertically oriented conduit 410 in fluid communication with the conduits 114. The conduit 410 may be adapted to supply the fuel gas to the conduits 114, to the volume 206, and ultimately to the apertures 112 to generate a flame.

The burner 402 is adapted to move, which can enable even distribution of the heat from the burner 402 onto a food item or cooking utensil such as a pot or pan. For example, as shown in FIG. 4C, the burner 402 is adapted to rotate about an axis 412, such as to more evenly distribute the heat from the burner 402 onto a food item or cooking utensil. In some examples, the burner 402 may generate a thrust at a location of one or more flames that causes the burner 402 to spin or translate. In another example, the burner 402 may be moved by a motor, gearbox, pulley, etc. For example, as shown in FIG. 4A, the burner 402 includes one or more apertures 112. The apertures 112 may be disposed adjacent to one or more respective deflectors 404. The deflectors 404 may be adapted to direct a thrust generated by a flame formed by the aperture 112 in a particular direction. The thrust may be directed at least partially tangential to portion of the wall 204 of the burner 402. As shown in FIG. 4C, the conduit 410 may be supported by one or more bearings 406 that enable the thrust generated by the flames to cause the burner 402 to rotate about the conduit 410. The conduit 410 may form all or a portion of the axis 412.

In other embodiments, the burner 402 may be moved by a motor, articulated arm, gantry (e.g., a three-axis, four-axis, five-axis, six-axis, or seven-axis motion mechanism), or manual input. For example, the burner 402 (or another burner disclosed herein) may be adapted to move around a food item, while the food item remains stationary. The burner may move around the food item to cook it uniformly, based for example on the size or shape of the food item.

With reference to FIG. 5A-FIG. 5F a burner 502 is disclosed. The burner 502 includes multiple apertures 112 arranged in a pattern and which may be selectively activated (e.g., opened) or deactivated (e.g., closed) to establish or extinguish a flame proximate to the aperture. The apertures 112 of the burner 502 may be selectively activated or deactivated to form one or more shapes, words, or symbols (collectively and individually “patterns”) via the flames 516 formed at one or more apertures 112 of the burner 502. The burner 502 may be configured to transfer the pattern 508 to a food item 514, such as searing the pattern 508 into a piece of meat. See, e.g., FIG. 5H-FIG. 5J.

As shown for example in FIG. 5A, the apertures 112 may be arranged in one or more rows 504 and/or columns 506. Thus, the apertures 112 may form an array or grid of locations at which a hydrogen flame 516 may be formed. The apertures 112 may be as described with respect to the apertures 112 of the burner 202 and/or burner 302 and/or as designed according to the method 700. In other words, the aperture 112 may have a diameter smaller than a quenching distance of the fuel gas to resist flashback. The wall 204 may be in the form of a substantially planar sheet, manifold, or plenum defining a volume 206. The fuel gas may be distributed to the apertures 112 via the volume 206. The distribution of the fuel gas to the apertures 112 may be substantially uniform, such that pressure gradients of the fuel gas within the volume 206 are minimized. The flow of the fuel gas through each of the apertures 112 (when activated or opened) may be substantially the same as the flow through any other activated aperture.

With specific reference to FIG. 5B and FIG. 5C, each of the apertures 112 may be selectively closable by one or more respective actuators 518. An open aperture 112 through which the fuel gas can flow and support a flame 516 may be described as an active aperture 512. A closed aperture 112, which is blocked by its respective actuator 518, through which fuel gas does not flow may be described as an inactive aperture 510. The actuators may be controllable by a processing element 802, such as in a controller 608, discussed below. In some examples, the actuators 518 may be motors, solenoids, dashpots, servos, power screws, stepper motors, resilient member (e.g., a spring), combinations of two or more of these, or any other mechanism suitable to control flow of the fuel gas through an aperture 112. For example, an actuator 518 may include a shaft 520 with a seal 522 coupled thereto. To activate an aperture 112, the actuator 518 may move the shaft 520 and the seal 522 away from the wall 204 adjacent to the aperture 112 thereby allowing the fuel gas to flow through the aperture 112 to form a flame 516. Conversely, an actuator 518 may move the shaft 520 and the seal 522 to plug the aperture 112 to substantially prevent the fuel gas from flowing through the aperture 112 and preventing formation of a flame 516. In some examples, the actuators 518 may act in a substantially binary mode of operation (e.g., on or off). In some examples, the actuators 518 may have a proportional control ability such that the flow of the fuel gas from an aperture may be controlled between a low value and a high value (e.g., a linear flow control). In such examples, the heat rate of an aperture 112 in the burner 502 may be controlled independently of other apertures 112. A benefit of such proportional control may be the ability to apply more heat to one portion of a pattern 508 and less heat to another portion of the pattern 508, such as to create a shading effect, halftone effect, pointillism effect, or the like. An additional benefit may be the ability to provide more heat to a portion of a food item 514 (e.g., a thicker portion) and less to another portion (e.g., a thinner portion) to provide for substantially even cooking of the food item 514.

As discussed herein, the absence of carbon from hydrogen gas results in flames 516 that are substantially less radiative compared to flames formed from burners adapted to burn hydrocarbon fuels such as methane, propane, butane, etc. Additionally, the relatively small size of the apertures 112 (e.g., selected for the flashback resistance) may be suitable to generate one or more patterns 508 on a food item 514, e.g., due to the small aperture size, density, and the low level of radiant energy of a hydrogen flame. Such heat-generated patterns are generally not possible via conventional hydrocarbon burners (even if they included small apertures) as a radiant flame generated from a hydrocarbon, is too diffuse to form a pattern 508 on a food item 514, and would result in a low-resolution or blurred pattern 508.

Food patterns, such as pattern 508 (which may be as a star or other shape) can be seared into the food item 514, such as to decorate the food item 514, include customer's initials, and/or an order number seared into the meat to avoid order confusion. Additionally, or alternately, a chef could use the burner 502 to “sign” a food item 514 such as by placing the chef's initials on a steak. In another example, a message could be provided on the food item such as “Happy Birthday!” In another example, a thicker portion of a food item 514 may have more or less heat applied thereto to control uniform cooking of the food item 514.

Additionally, or alternately, the apertures 112 of the burner 502 may be adapted to form an active region of a similar size and shape as a cooking utensil like a pot, pan, skillet, etc. A benefit of the burner 502 may be that the active region where one or more apertures 112 are open and producing a flame 516 may be sized and shaped to match a cooking utensil thereby efficiently heating the utensil, rather than activating regions that do not heat the utensil, thereby saving fuel, as well as allowing decreased cooking times, or customization for individual chefs. Further, the burner 502 can be customized for substantially any type or size of cookware, recipe, or user preferences.

FIG. 6A shows an example of a system 600 including a cooking apparatus 602 including a burner 502. The system 600 may be compatible with other burners disclosed herein, including the burner 202, burner 302, and/or burner 402.

The cooking apparatus 602 may include a grate 604 above the burner 502 configured to support a food item 514 or a cooking utensil (e.g., pot, pan, skillet, etc.). The cooking apparatus 602 may include a vent 618 in a hood thereof. The vent 618 may be a louvered vent or other suitable apparatus that can contain heat within the hood of the cooking apparatus when closed but allow un-combusted hydrogen to escape from the cooking apparatus, e.g., in the event of an igniter failure, thereby providing a beneficial safety feature. The cooking apparatus 602 may include an actuator 606 suitable to operate a control item of the burner 502. For example, the actuator 606, such as a knob or lever, may enable a user to control a needle valve 106, a pressure regulator 116, a shutoff valve 118, etc. In some embodiments, more than one actuator 606 may be provided to control different aspects of the burner 502 such as fuel gas pressure and/or flow rate.

The system 600 may include, or be in communication with, a controller 608. The controller 608 may be physically packaged with the cooking apparatus 602 or may be separate and be communicatively coupled thereto. The system 600 may optionally include a user device 612 and/or a network 614. The user device 612 may be a smart phone, computer, laptop, tablet, smart watch, or other computing device. The network 614 may be substantially any device or system that enables electronic communication between the user device 612 and the controller 608. For example, the network 614 may be a wired or wireless network. The network 614 may be an Ethernet, Wi-Fi, Bluetooth, Wi-Max, Zigbee, or other data transmission network. In some embodiments, the user device 612 may communicate with the controller via the network 614. In some embodiments, the user device 612 may communicate directly with the controller 608. In some embodiments, the user device 612 may be optional and the user 610 may interface with the controller 608 via an input/output interface 810 (see, e.g., FIG. 8).

The user 610 may control the operation of the apertures 112 of the burner 502 via the controller 608, either directly or via a user device 612. For example, the controller 608 and/or the user device 612 may include a processing element 802 that executes an application enabling the user to input or select a pattern 508 to be replicated on the pattern 508 via opening or modulating the flow of fuel gas (e.g., hydrogen) via the respective actuators 518. In some embodiments, the memory component 806 of the user device 612 or the controller 608 includes a pattern library including one or more patterns that can be replicated by the burner 502. As shown, for example in FIG. 6, the user 610 may select a star pattern 508 via the user device 612. The user device 612 may communicate the desired pattern 508 to the controller 608. The controller 608 may then operate the appropriate actuators 518 to open the respective apertures to cause a star pattern to be replicated with individual flames 516. In some embodiments, the user 610 can draw a pattern via an input/output interface 810 (e.g., via a touch screen) or display 804 of the user device 612 or the controller 608 and configure the controller 608 to replicate the pattern 508 on the burner 502. In some embodiments, the user 610 may take a picture with a camera of the user device 612 and cause the picture to be replicated as a pattern 508 by the burner 502.

As discussed below; if the apertures 112 of a flashback resistant burner are too far apart, it may be difficult for a flame 516 at one aperture 112 to ignite the fuel gas at an adjacent aperture 112. This feature of a flashback resistant burner may make it difficult to ignite apertures 112 forming a pattern 508, especially with a single igniter 616 located at the periphery of the burner 502 as shown for example in FIG. 6A-6B, below: To overcome this issue, the actuators 518 may be operated in sequence to “carry” a flame 516 from a location proximate to an igniter 616, across the burner 502, to a pattern location 526 and ignite the fuel gas at the apertures 112 forming the pattern 508.

As shown in FIG. 5D-FIG. 5G, in some embodiments, to ignite the fuel gas flowing through the apertures 112 forming the pattern 508 at a pattern location 526, the controller 608 may temporarily open one or more apertures 112 near an igniter 616 (e.g., an igniter such as a piezoelectric igniter, spark igniter, hot surface igniter, pilot light, etc.). For example, as shown in FIG. 5D, one or more apertures 112 may be opened adjacent to an igniter, becoming active apertures 512, supporting respective pilot flames 524. As shown for example in FIG. 5E, at a later time than shown in FIG. 5D, one or more apertures 112 may be configured as active aperture 512 carrying the pilot flame 524 toward the pattern location 526. The initial active aperture 512 adjacent to the igniter 616 may be deactivated, becoming an inactive aperture 510. As shown for example in FIG. 5F, at a time later than shown in FIG. 5D or FIG. 5E, one or more apertures 112 may be configured as active aperture 512 carrying the pilot flame 524 even further toward the pattern location 526. Again, the trailing edge of actuators 112 may be deactivated as the pilot flame 524 passes toward the pattern location 526. As shown for example, in FIG. 5G, the pilot flames 524 may ignite the fuel gas at the active apertures 512 forming the pattern 508, and the apertures 112 supporting the pilot flames 524 may be deactivated, extinguishing the pilot flames 524. This method of igniting the apertures at a pattern location 526 may be execute by a controller 608 operating the actuators 518 in a concerted sequence. In this way, the burner 502 has the benefit of providing reliable ignition of the fuel gas at any of the apertures with a single igniter. The “carrying” of a flame 516 across the burner 502 is not limited to the simple linear example shown in FIG. 5D-FIG. 5G, which is merely illustrative in nature and by no means limiting. Rather, flames 516 may be moved across a burner 502 in any direction, in one, two, and/or three dimensions, and at a variety of speeds. For example, the methods and devices disclosed herein may be used to provide animation effects on the burner 502 by selectively opening and closing or proportionally modulating actuators 518 in a coordinated manner over time.

With reference to FIG. 7A to FIG. 7B, a method 700 of designing a flashback resistant burner is disclosed. The burners of the present disclosure may be designed to accommodate a number of competing factors to meet a given application. For example, while smaller apertures reduce the risk of flashback with high flames speed gases such as hydrogen, smaller apertures limit gas flow and thus heat rate for a given application. To overcome such challenges, the burners 102, 202, 302, 402, and/or 502 include features to reduce flashback risk, while also meeting desired application parameters such as heat rate, etc. One example of a method of designing a burner of the present application is as follows:

The method 700 may begin in operation 702 and the desired heat output of a burner is determined based on parameters of the application. For example a grill may be designed with a heat output of approximately 3.5 W/cm²to about 4.5 W/cm²of grill area.

The method 700 may proceed to operation 704 and a source of hydrogen and possible pressure range during operation are determined. Pressure ranges may be based at least in part on the source of hydrogen. For example, a compressed gas cylinder may be able to supply gas at pressures up to about 750 bar. Whereas an electrolyzer may operate at a pressure of about 10-60 bar.

The method 700 may proceed to operation 706 where the use of a line orifice 108 is determined. For example, a system utilizing both a pressure regulator and a line orifice 108 may be desired to provide flexibility and safety for the system.

When a line orifice 108 is used, the method 700 may proceed to operation 708 where the characteristic of the flow through the line orifice 108 is determined to be choked (e.g., sonic or supersonic) or unchoked (e.g., subsonic).

When the flow through the line orifice is choked, the method 700 may proceed to operation 710 where the line orifice 108 may be sized in a choked flow case for example using Eq. 2, below, where p_i.LOis the inlet pressure to the line orifice, S_LOis the orifice cross sectional area and C_dis the coefficient of discharge of the line orifice 108, γ is the ratio of constant volume and constant pressure specific heats, M the molecular mass, Z the compressibility factor, and T the temperature of the gas exiting the line orifice, Q is the desired heat output of the burner, and LHV is the lower heating value of the gas.

$\begin{matrix} S_{L O} = \frac{\frac{Q}{L H V}}{p_{i, L O} C_{d} \sqrt{γ \frac{M}{Z R T} {(\frac{2}{γ + 1})}^{(γ + 1) / (γ - 1)}}} & (Eq . 2) \end{matrix}$

When the flow through the line orifice is unchoked, the method 700 may proceed instead to operation 712 and the line orifice size is determined for unchoked flow. In some cases, the input pressure may be so low that the flow through the line orifice is unchoked, and the following equation 3 may be used. The variables are the same as in Eq. 2, above, and p_o.LOis added to represent the outlet pressure of the line orifice.

$\begin{matrix} S_{L O} = \frac{\frac{Q}{L H V}}{p_{i, L O} C_{d} \sqrt{\frac{M 2 γ}{ZRT γ - 1} [1 - {(\frac{p_{o, LO}}{p_{i, LO}})}^{(γ - 1) / γ}]} {(\frac{p_{o, LO}}{p_{i, LO}})}^{1 / γ}} & (Eq . 3) \end{matrix}$

When the line orifice 108 size is determined, or if a line orifice 108 is not used, the method 700 may proceed to operation 714 and the burner aperture hole size and quantity is determined. The burner aperture hole size may be determined based upon the desired flame length, quenching distance, and desired heat output. The burner aperture quantity is determined by the desired heat output and desired spacing between apertures.

The method 700 may proceed to operation 716 where the characteristic of the flow through the burner aperture(s) is checked to see whether flow therethrough choked or unchoked.

When the flow through the burner aperture(s) is choked, the method 700 may proceed to operation 718 where the pressure within the burner may be determined in a choked flow case for example using Eq. 4, below, where p_Bis the pressure within the burner, S_Bis the area and C_dis the coefficient of discharge of each burner aperture(s), n is the number of burner apertures, γ is the ratio of specific heats, M the molecular mass, Z the compressibility factor, and T the temperature of the gas exiting the burner aperture, Q is the desired heat output of the burner, and LHV is the lower heating value of the gas.

$\begin{matrix} p_{B} = \frac{\frac{Q}{L H V}}{n S_{B} C_{d} \sqrt{γ \frac{M}{Z R T} {(\frac{2}{γ + 1})}^{(γ + 1) / (γ - 1)}}} & (Eq . 4) \end{matrix}$

When the flow through the line orifice is unchoked, the method 700 may proceed instead to operation 720 where the pressure within the burner may be determined in an unchoked flow case using Eq. 5, below, and an aperture size is determined for unchoked flow. In some cases, the input pressure may be so low that the flow through the aperture is unchoked, and the following equation 5 may be used. The variables are the same as in Eq. 4,above, and p_ais added to represent the atmospheric pressure.

$\begin{matrix} p_{B} = \frac{\frac{Q}{L H V}}{{nS}_{B} C_{d} \sqrt{\frac{M 2 γ}{ZRT γ - 1} [1 - {(\frac{p_{a}}{p_{B}})}^{(γ - 1) / γ}]} {(\frac{p_{a}}{p_{B}})}^{1 / γ}} & (Eq . 5) \end{matrix}$

The method 700 may proceed to operation 722 where, if a line orifice 108 is used, the pressure of the burner determined from Eq. 4 or Eq. 5 above is compared to the pressure downstream of the line orifice 108 and if needed, the method 700 proceeds back to operation 706 to iterate the previous steps until convergence.

The method 700 may proceed to operation 724 where the results are compared against the physical constraints of the burner including overall size, desired flame length, and distance between burner apertures to allow for cross-ignition (as discussed below). The method 700 may be iterated by repeating operations 706-724 until the following are within acceptable limits, for example:

- a. Heat output of the burner. For example, +/−100 W for a nominal 2 KW burner.
- b. Pressure within the burner (within structural capability of the burner). For example, maximum pressure in a failure scenario of less than 1,300 psig for a burner made out of 0.5 inch diameter stainless steel tubing with 0.02 inch wall thickness.
- c. Flame length. For example, between 2-4 cm for a barbecue grill.
- d. Number of apertures. For example, less than 5 per linear centimeter for machinability.
- e. Size of aperture (less than quenching distance for the range of expected operating values). For example, less than 0.8 mm when the burner pressure is at atmospheric pressure, or less than 0.4 mm when the burner pressure is at 2.5 atm, but more than 0.1 mm for constructability.
- f. Distance between apertures (to enable cross-ignition). For example, less than 10 mm.

The method 700 may proceed to operation 726 where transient conditions may be checked. For example, if the system has an ability to adjust the heat output (for example by throttling a valve, or a pressure regulator) the range of operation may be checked so that the system continues to operate satisfactorily in all conditions. This includes checking the aperture size is less than the quenching distance even if input temperature or pressure changes.

Additionally or alternately, in operation 726, safety conditions may be checked. Primarily, the calculations may be repeated for the worst-case scenario or regulator breakage leading to full source pressure upstream of the line orifice, and checking whether the burner is designed to handle the increased internal pressure without rupture. The method 700 may be iterated until results are within acceptable limits. The operations of the method 700 may be performed in an order other than as described, some operations may be executed in parallel, some operations may be omitted. The method 700 may end at operation 728.

In the burners of the present disclosure, hydrogen exits an aperture as a narrow jet even when the upstream pressure is only slightly above atmospheric pressure. Increases in upstream pressure result in a longer jet. The pressure within the burner (upstream pressure) for a given number of apertures of a given size increases as the mass flow rate for a given heat requirement increases. Therefore, for a given heat requirement, fewer apertures will increase the pressure within the burner and result in flames that may be too high or long for the application. The number of apertures (n) to achieve a desired upstream pressure (p) for a required mass flow rate (W_g) can be found by Eq. 6 when the flow through the burner apertures is choked:

$\begin{matrix} n = \frac{W_{g}}{p C_{d} S \sqrt{γ \frac{M}{Z R T} {(\frac{2}{γ + 1})}^{(γ + 1) / (γ - 1)}}} & (Eq . 6) \end{matrix}$

Experiments were conducted to find the optimal upstream (burner) pressure that gives the desired flame length for the application. For example, the flame length for cook stoves is generally about 1 cm and optimized to transfer heat to the bottom of a piece of cookware less than 2 cm away: the flame length for a barbecue is about 2-4 cm long and designed to transfer heat to a grill approximately 15-20 cm away: and the desired flame length for a decorative burner may be 30 cm or more. Eq. 6 above can be used to determine the number of apertures if solved for n. If, for example, a desired heat output of 4.5 KW (about 15,000 Btu/hr) is required, for example for a barbecue, it was found by the applicant that two burners each with 60 apertures of 0.4 mm diameter would lead to an upstream pressure of 106 kPa in each burner, and in turn the flames were approximately 2-3 cm in length, which was suitable for that application.

The placement and orientation of apertures may also be considered. Hydrogen does not contain carbon, so its flames produce much less radiative heat than flames from conventional, carbon containing fuels such as butane, natural gas, or propane. This means that the heat from a hydrogen flame is much more localized to the actual flame zone compared to conventional fuel gases, and as mentioned above flames from a hydrogen jet are narrow. An advantage of burners using hydrogen is that the heat produced can be directed and captured easily, making the overall system more efficient because less heat is lost to the surroundings, i.e., is unused by the system. Therefore, the apertures on the burner should be placed and oriented in a way that effectively transmits heat to the desired area. Experiments were conducted by the applicant to find the optimal placement of apertures on a given circular cross-section burner tube. It was found, for example, that a single row of apertures all facing in the same direction on a linear burner with circular cross section will produce a linear hot zone of heat (see, e.g., the burner 302). This arrangement could be desirable for some applications that use focused or directed heat sources, for example process heating or specialized cooking. It was also found, for example, that two rows of apertures staggered off-center and oriented at 90 degrees from each other produced an even heating on a grill plate approximately 20 cm away (see, e.g., the burner 202). This arrangement could be desirable for applications that use even heating such as cooking grills or space heaters. In the burners of the present disclosure the location and placement of the apertures to achieve the desired heat distribution may be customizable to meet the need of the end application.

Another factor in placement of apertures 112 is the distance 208 (see, e.g., FIG. 2B and FIG. 3B) between each aperture 112. On a burner it is convenient for the flame of one aperture to be able to ignite the fuel gases emitting from an adjacent aperture. In this way, ignition of the fuel gas at one aperture will propagate to all apertures. Flames from one aperture being able to ignite fuel gases emitting from adjacent apertures makes ignition simpler and it also acts as a safety feature in case one or more apertures somehow were to stop combusting, for example because of an inert impurity in the fuel gas or gust of wind. As mentioned above, a hydrogen jet flame is narrow and emits little radiant energy, which can make such aperture-to-aperture propagation challenging. In experiments by the applicant, it was found that if the distance 208 between apertures was too large, for example approximately 20 mm between apertures, the flame from one aperture would not ignite the fuel gases emitting from an adjacent aperture, but when the distance 208 was decreased, for example to approximately 6 mm between apertures (see, e.g., FIG. 2B), the flame from one aperture would ignite the fuel gases emitting from an adjacent aperture. In other embodiments, the distance 208 between apertures may be approximately 3 mm (see, e.g., FIG. 3B). In other embodiments, the distance 112 may be other values, such as 1 mm, 2mm, 4 mm, 5, mm, 7 mm, 8 mm, 9 mm, 10 mm, 12 mm, 13 mm, 14 mm, or 15 mm.

Hydrogen's unique physical and combustion properties mean that burner designs that work for conventional fuel gases such as natural gas, propane, or butane may lead to ineffective or unsafe situations when used for hydrogen. The burners of the present disclosure include the aspects needed to optimize a hydrogen burner for each application: aperture size, quantity, orientation, and spacing. As an example, in one embodiment for a barbecue, two burner tubes each including of 2 rows of 30 apertures oriented at 90 degrees from each other, spaced 6 mm apart, each with a diameter of 0.4 mm, will give a 2-3 cm flame length at a burner tube pressure of 106 kPa and emit approximately 4.5 kW of heat, matching the performance of a standard propane barbecue of the same size at 15,000 Btu/h and even heat distribution at the grill surface.

Fuel Distribution

In some embodiments, conduit 114, valving, and instrumentation can be used to convey and control hydrogen from the fuel gas source 110 to the burner(s) burner 102, 202, 302, 402, 502, etc.

Flow restriction can be used to control the flow rate of the flammable gas to the burner. In one embodiment, a flow restrictor 108, such as an orifice, restricts flow and provides a flow rate to the burner that depends only upon the pressure of the fuel gas source 110. This is a convenient, simple, and reliable way to provide a fixed flow rate when the fuel gas source pressure is fixed. This could be used, for example, in a furnace or heater where the source pressure and heat output are fixed. A shutoff valve 118 could be used in conjunction with a line flow restrictor 108 to provide the ability to turn the flow on or off. An example of this is shown in FIG. 1C and FIG. 1D. The shutoff valve 118 could be manually controlled or remotely actuated.

In some cases it may be desirable to control the heat output. This could be done with adjustable flow restriction such as a needle valve 106 and/or pressure regulator 116. The amount of heat delivered by the burner may be adjusted in proportion by adjusting the flow restrictor. The burner tube and flow restrictor are sized according to the application parameters: a larger opening will allow more flow to pass and result in more heat output.

In some cases the fuel gas source will be at a higher pressure than the desired burner pressure. For example, if the desired burner pressure is 106 kPa and the source is a tank of compressed fuel gas at 35 MPa. In these cases, a single needle valve or pressure regulator will not likely have enough precision to control the burner flow to the degree desired by the user. In these cases, it is desirable to include the line orifice 108 downstream of the flow restrictor. The flow restrictor is then used to control the pressure upstream of the line orifice, which in turn controls the final burner pressure and flow rate. The size of the line orifice is determined by the desired flow rate of fuel gas and heat output of the burner. For example, a line orifice of 0.23 mm with an upstream pressure of 1.2 MPa will provide a flow rate of hydrogen corresponding to a heat load of approximately 2.25 kW.

The line orifice also serves a safety function. In the event of failure of a component (for example the needle valve 106, pressure regulator 116, or shutoff valve 118 leading to unregulated pressure the flow restrictor 108 chokes the flow and prevents the burner 102 from experiencing a higher pressure than it is designed for. This arrangement does not require additional safety components, such as a pressure relief valve, to maintain safe operation. This results in a cost-effective, reliable, safe and effective system suitable for any application.

A filter 104 can be installed before the flow restriction to prevent ingress of foreign material. The filter can have an opening size of, for example, 1 micron (micrometer), 2micron, 5 micron, 10 micron, 20 micron, 40 micron, 50 micron, 80 micron, 100 micron, or other opening size. This is particularly important for hydrogen burners because the apertures may be very small, for example 0.4 mm (400 micron) and many piece of foreign material could readily clog the aperture or line orifice 108. It is also important because flow restrictor 106 or 116 performance can be compromised (e.g., not able to properly restrict flow; or not able to fully close) if foreign material is present.

Instrumentation, for example one or more pressure sensors 120, can be installed between the fuel gas source 110 and the burner to provide feedback to the user when the flame and can be correlated to heat output, flame length, or other parameter of interest. This may be especially useful in stances where the flame itself may not be visible to the user.

Additional burners can be manifolded downstream of the line orifice allowing all burners to have the same heat output at the same times. If different flow rates at different burners are desired, additional line orifices and burners can be manifolded downstream of the flow restrictor and if the line orifices are different sizes this gives different flow rates through each burner. Additional flow restrictors, line orifices, and burners can be manifolded either upstream or downstream of the filter which will give fully independent control over each burner(s).

FIG. 8 illustrates a simplified block diagram for a controller 608 or user device 612. As shown, the various devices may include one or more processing elements 802, an optional display 804, one or more memory components 806, a network interface 808, a power supply 126, an input/output interface 810, and/or an actuator driver 812, where the various components may be in direct or indirect communication with one another, such as via one or more system buses, contract traces, wiring, or via wireless mechanisms.

The one or more processing elements 802 may be substantially any electronic device capable of processing, receiving, and/or transmitting instructions. For example, the processing element 802 may be a microprocessor, microcomputer, graphics processing unit, or the like. It also should be noted that the processing elements 802 may include one or more processing element or modules that may or may not be in communication with one another. For example, a first processing element may control a first set of components of the computing device and a second processing element may control a second set of components of the computing device where the first and second processing elements may or may not be in communication with each other. Relatedly, the processing elements may be configured to execute one or more instructions in parallel locally, and/or across the network 614, such as through cloud computing resources.

The display 804 may be optional and provides an input/output mechanism for the controller 608 and/or user device 612, such as to display visual information (e.g., images, graphical user interfaces videos, notifications, and the like) to a user, and in certain instances may also act to receive user input (e.g., via a touch screen or the like). The display may be an LCD screen, plasma screen, LED screen, an organic LED screen, or the like. The type and number of displays may vary with the type of devices (e.g., smartphone versus a desktop computer).

The memory components 806 store electronic data that may be utilized by the controller 608 and/or user device 612, such as audio files, video files, document files, programming instructions, pattern libraries for the burner 502, and the like. The memory components 806 may be, for example, non-volatile storage, a magnetic storage medium, optical storage medium, magneto-optical storage medium, read only memory, random access memory, erasable programmable memory, flash memory, or a combination of one or more types of memory components.

The network interface 808 may be optional and receives and transmits data to and from a network 614 to the controller 608. The network interface 808 may transmit and send data to a network 614 directly or indirectly. For example, the network interface 808 may transmit data to and from other computing devices through the network 614. In some embodiments, the network interface 808 may also include various modules, such as an application program interface (API) that interfaces and translates requests across the network 614 to the specific device.

The controller 608 or user device 612 may also include a power supply 126. The power supply 126 provides power to various components of the controller 608 or user device 612. The power supply 126 may include one or more rechargeable, disposable, or hardwire sources, e.g., batteries, power cord, AC/DC inverter, DC/DC converter, or the like. Additionally, the power supply 126 may include one or more types of connectors or components that provide different types of power to the controller 608 or user device 612. In some embodiments, the power supply 126 may include a connector (such as a universal serial bus) that provides power to the computer or batteries within the computer and also transmits data to and from the device to other devices.

The input/output interface 810 allows the controller 608 or user device 612 to receive input from a user 610 and provide output to a user 610. In some devices, the input/output interface 810 may be optional. For example, the input/output interface 810 may include a capacitive touch screen, keyboard, mouse, stylus, or the like. The type of devices that interact via the input/output interface 810 may be varied as desired.

The user device 612 may include an actuator driver 812 configured to operate the plurality of actuators 518 in the burner 502. For example, the actuator driver 812 may be in electrical communication with one or more actuators 518 and configured to cause the actuators 518 to open, close or modulate flow of the fuel gas through the respective apertures 112 operatively associated with a respective actuator 518.

The description of certain embodiments included herein is merely exemplary in nature and is in no way intended to limit the scope of the disclosure or its applications or uses. In the included detailed description of embodiments of the present systems and methods, reference is made to the accompanying drawings which form a part hereof, and which are shown by way of illustration specific to embodiments in which the described systems and methods may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice presently disclosed systems and methods, and it is to be understood that other embodiments may be utilized, and that structural and logical changes may be made without departing from the spirit and scope of the disclosure. Moreover, for the purpose of clarity, detailed descriptions of certain features will not be discussed when they would be apparent to those with skill in the art so as not to obscure the description of embodiments of the disclosure. The included detailed description is therefore not to be taken in a limiting sense, and the scope of the disclosure is defined only by the appended claims.

From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention.

The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for the fundamental understanding of the invention, the description taken with the drawings and/or examples making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

As used herein and unless otherwise indicated, the terms “a” and “an” are taken to mean “one”, “at least one” or “one or more”. Unless otherwise required by context, singular terms used herein shall include pluralities and plural terms shall include the singular.

Unless the context clearly requires otherwise, throughout the description and the claims, the words ‘comprise’, ‘comprising’, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. Words using the singular or plural number also include the plural and singular number, respectively. Additionally, the words “herein,” “above,” and “below” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of the application.

Of course, it is to be appreciated that any one of the examples, embodiments or processes described herein may be combined with one or more other examples, embodiments and/or processes or be separated and/or performed amongst separate devices or device portions in accordance with the present systems, devices and methods.

Finally, the above discussion is intended to be merely illustrative of the present system and should not be construed as limiting the appended claims to any particular embodiment or group of embodiments. Thus, while the present system has been described in particular detail with reference to exemplary embodiments, it should also be appreciated that numerous modifications and alternative embodiments may be devised by those having ordinary skill in the art without departing from the broader and intended spirit and scope of the present system as set forth in the claims that follow. Accordingly, the specification and drawings are to be regarded in an illustrative manner and are not intended to limit the scope of the appended claims.

FLASHBACK RESISTANT BURNER

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