WO2015023004A1

WO2015023004A1 - Portable burner device and method

Info

Publication number: WO2015023004A1
Application number: PCT/KE2014/000038
Authority: WO
Inventors: Jonathan Baker
Original assignee: Develatech Limited
Priority date: 2013-08-16
Filing date: 2014-08-15
Publication date: 2015-02-19

Abstract

A portable burner device comprising: a cone-shaped potholder (10) configured to support a cooking pot; a flame hole (12) at the apex of the cone-shaped potholder; a firebox (30) comprising a heat outlet (32) configured to allow heat to escape from the firebox and a fuel inlet (33) configured to receive solid fuel; a firetube (20) configured to enable heat to transfer from the firebox to the cone-shaped potholder via the heat outlet, the firetube comprising: a riser section comprising a top and a base, wherein the top is in communication with the flame hole; and a transfer section intersecting the riser section at its base and further in communication with the heat outlet of the firebox.

Description

Portable Burner Device and Method

Cross-Reference to Related Applications

This application claims priority to Kenya patent application Serial Number KE/UM/2013/00378, filed 16 Aug 2013, the disclosure of which is incorporated by reference.

Technical Field of the Invention

In various embodiments, the invention pertains to devices for producing and utilizing heat.

Background

Since developing an ability to control fire, mankind has been continuing to innovate in the area of burner devices. Burning solid fuel is a central aspect of many societies, whether such burning is for heating dwellings or for cooking food. Indeed controlling fire for these purposes is a fundamental distinction between humans and all other animals. Nevertheless, there remains a need for improving modern methods and devices of burning solid fuel. The growing scarcity of fuel and the environmental impact of burning such fuel necessitate the continued development of highly efficient devices and methods.

Relevant art: USPN 5797386; USPN 7958884; and WO 2013/051923.

Summary of the Invention

In an aspect, the invention provides a portable burner device comprising:

a cone-shaped potholder configured to support a cooking pot; a flame hole at the apex of the cone-shaped potholder; a firebox comprising a heat outlet configured to allow heat to escape from the firebox and a fuel inlet configured to receive solid fuel; a firetube configured to enable heat to transfer from the firebox to the cone-shaped potholder via the heat outlet, the firetube comprising: a riser section comprising a top and a base, wherein the top is in communication with the flame hole; and a transfer section intersecting the riser section at its base and further in communication with the heat outlet of the firebox.

In embodiments: the device further comprises an outer insulating tube surrounding the riser section and at least a portion of the transfer section of the firetube;

the firebox further comprises a removable insert configured to retain ashes for removal from the device;

the fuel inlet is configured to receive solid fuel in a substantially vertical orientation;

the heat outlet is configured to allow heat to escape substantially horizontally from the firebox;

the firebox further comprises a removable insert configured to retain ashes for removal from the device; and wherein the fuel inlet is configured to receive solid fuel in a substantially vertical orientation; and wherein the heat outlet is configured to allow heat to escape substantially horizontally from the firebox;

the firetube comprises air inlet holes along at least a portion of the transfer section;

the device further comprises a plurality of reinforcing members disposed in the cone-shaped potholder;

wherein the reinforcing members provide pot grips to prevent sliding of the pot (e.g., when stirring);

wherein the reinforcing members are configured to elevate the pot away from the potholder surface to provide airflow between the pot and the potholder;

the reinforcing members comprise notches configured to allow a pot to rest on the reinforcing members;

the reinforcing members are radial strips;

the reinforcing members are configured (e.g., have a thickness) to elevate a pot resting on the potholder such that the pot does not form a seal with the potholder and such that there is provided airflow space between the pot and the potholder;

the reinforcing members comprise notches configured to allow a pot to rest on the reinforcing members, the reinforcing members are radial strips, and the reinforcing members are configured (e.g., have a thickness) to elevate a pot resting on the potholder such that the pot does not form a seal with the potholder and such that there is provided airflow space between the pot and the potholder;

the device further comprises an outer insulating tube surrounding the riser section and a carrying handle attached to the outer insulating tube; the device further comprises a housing enclosing the firebox and transfer section of the firetube;

the firetube comprises air inlet holes along at least a portion of the transfer section, and the device further comprises an outer insulating tube surrounding at least the riser section;

the device further comprises: a second cone-shaped potholder configured to support a cooking pot; a second flame hole at the apex of the second cone-shaped potholder; a second heat outlet separate from the first heat outlet and configured to allow heat to escape from the firebox; a second firetube configured to enable heat to transfer from the firebox to the second cone-shaped potholder via the second heat outlet, the second firetube comprising: a second riser section comprising a top and a base, wherein the top is in communication with the second flame hole; and a second transfer section intersecting the second riser section at its base and further in communication with the second heat outlet of the firebox; and

the device further comprises: a third cone-shaped potholder configured to support a cooking pot; a third flame hole at the apex of the third cone-shaped potholder; a third heat outlet separate from the first and second heat outlets and configured to allow heat to escape from the firebox; a third firetube configured to enable heat to transfer from the firebox to the third cone-shaped potholder via the third heat outlet, the third firetube comprising: a third riser section comprising a top and a base, wherein the top is in communication with the third flame hole; and a third transfer section intersecting the third riser section at its base and further in communication with the third heat outlet of the firebox.

In an aspect, there is provided a portable burner device comprising: a first potholder configured to support a cooking pot and comprising a first flame hole disposed centrally; a second potholder configured to support a cooking pot and comprising a second flame hole disposed centrally; a firebox comprising: a first heat outlet and a second heat outlet, the first and second heat outlets configured to allow heat to escape from the firebox; and a fuel inlet configured to receive solid fuel; a first firetube configured to enable heat to transfer from the firebox to the first potholder via the first heat outlet, the firetube comprising: a riser section comprising a top and a base, wherein the top is in communication with the flame hole; a transfer section intersecting the riser section at its base and further in communication with the first heat outlet of the firebox; a second firetube configured to enable heat to transfer from the firebox to the second potholder via the second heat outlet, the firetube comprising: a second riser section comprising a top and a base, wherein the top is in communication with the flame hole; and a transfer section intersecting the riser section at its base and further in communication with the second heat outlet of the firebox.

In an aspect, there is provided a method for providing heat to a cooking pot, the method comprises placing a pot on the potholder of the device, feeding solid fuel to the firebox, and combusting the fuel in the firebox, wherein the combusting produces heat and at least a portion of the heat is transferred through the firetube to the pot on the potholder.

These and other aspects of the invention will be apparent from the disclosure provided herein, including the appended claims.

Brief Description of the Drawings

FIG. 1A is a profile drawing of a single-burner device according to one embodiment of the invention.

FIG. IB is an isometric drawing of a single-burner device according to one embodiment of the invention.

FIG. 2 is an isometric drawing of a double-burner device according to one embodiment of the invention.

FIG. 3 is an isometric drawing of a three-burner device according to one embodiment of the invention.

FIG. 4 is an isometric drawing of a four-burner device according to one embodiment of the invention.

Detailed Description of Various Embodiments

In an aspect, there is provided a portable burner device comprising: a cone- shaped potholder configured to support a cooking pot; a flame hole at the apex of the cone-shaped potholder; a firebox comprising a heat outlet configured to allow heat to escape from the firebox and a fuel inlet configured to receive solid fuel; a firetube configured to enable heat to transfer from the firebox to the cone-shaped potholder via the heat outlet, the firetube comprising: a riser section comprising a top and a base, wherein the top is in communication with the flame hole; a transfer section intersecting the riser section at its base and further in communication with the heat outlet of the firebox.

In another aspect, there is provided a portable burner device comprising: a first potholder configured to support a cooking pot and comprising a first flame hole disposed centrally; a second potholder configured to support a cooking pot and comprising a second flame hole disposed centrally; a firebox comprising: a first heat outlet and a second heat outlet, the first and second heat outlets configured to allow heat to escape from the firebox; and a fuel inlet configured to receive solid fuel; a first firetube configured to enable heat to transfer from the firebox to the first potholder via the first heat outlet, the firetube comprising: a riser section comprising a top and a base, wherein the top is in communication with the flame hole; a transfer section intersecting the riser section at its base and further in communication with the first heat outlet of the firebox; a second firetube configured to enable heat to transfer from the firebox to the second potholder via the second heat outlet, the firetube comprising: a second riser section comprising a top and a base, wherein the top is in communication with the flame hole; a transfer section intersecting the riser section at its base and further in communication with the second heat outlet of the firebox.

The burner device comprises a potholder. The potholder is configured to support a cooking pot. Operationally, it is not necessary for the potholder to be in use (e.g., for the potholder to be holding a pot) in all instances, such as when the burner device is being used as a space heater.

In embodiments, the potholder comprises a metal such as aluminum, stainless steel, iron, or the like, or may be made from clay or a similar material. In embodiments, the potholder is prepared from a sheet of metal (e.g., sheet aluminum, etc., either rolled or pressed), and for such embodiments there are references herein to a "surface" of the potholder. In embodiments, the potholder is prepared from a rope or wire of such materials, and forms a coil or set of concentric circles. In embodiments, the potholder is painted or otherwise coated with a rust-resistant and/or heat-resistant paint or coating, such as an enamel coating.

In embodiments, the potholder is flat (i.e., not cone-shaped) and provides a platform upon which a pot can be placed. For flat potholders, slip-prevention members (e.g., spikes, etc.) may be present to prevent pots from sliding on the potholder during use. In embodiments, the potholder is cone-shaped. Unless otherwise specified, the term "cone-shaped" is meant to include bowl-shaped, wherein bowl-shaped is characterized by radially curved surfaces whereas cone-shaped is characterized by radially flat surfaces. In embodiments, the potholder is cone-shaped and has radially flat surfaces. Unless specified otherwise, the potholder is a right circular cone. The height of the cone (which determines the steepness of the cone as well as the perimeter of the base) can vary depending on the type of burner device desired and depending on the size of pots that should be accommodated. In embodiments, the height of the cone is between 1-30, 1-20, 1-15, 1-12, 2-10, 2-8 or 2-6 inches, or is greater than or equal to 1, 2, 3, 4, 5, or 6 inches, or is less than or equal to 12, 10, 8, 6, 5, 4, or 3 inches, or is greater than or equal to 10, 15, 20, or 25 inches, or is less than or equal to 30, 25, 20, or 15 inches. In embodiments, the perimeter of the base is in the range 3-220, 4-150, 4-100, 4- 75, 4-50, 4-20, 4-16, 4-12, or 6-12 inches, or is greater than or equal to 4, 6, 8, 10, 12, 15, 20, 25, 50, 75, 100, 150, or 200 inches, or is less than or equal to 220, 200, 150, 100, 75, 50, 20, 16, 14, 12, 10, or 8 inches. In embodiments, the diameter of the base is in the range 1-70, 3-60, 3-50, 5-40, 5-30, or 5-20 inches, or is greater than or equal to 1, 3, 5, 7, 10, 13, 15, 17, 20, 30, 40, 50, or 60 inches, or is less than or equal to 70, 60, 50, 40, 30, 20, 15, 10, 7, or 5 inches. It will be appreciated that references to the "base" of the cone are in the mathematical sense [i.e., the largest circle formed by a cross-section of the cone) rather than any physical orientation (i.e., the "base" may be oriented at the top of the device). The diameter of the base is illustrated as label 16 in FIG. 1A. It will further be appreciated that the "height" of the cone as the term is used herein refers to the height of the actual portion of the cone that is present. Thus, since the cone tip is not present (due to the presence of the flame hole, as described herein), the height of the cone is measured (along the cone's central axis) from the upper rim to the flame hole of the cone. The height is illustrated as label 15 in FIG. 1A.

In use, where the potholder is cone-shaped, a pot can be placed into the potholder and contacts the potholder only around the circumference of the base of the pot, or only where the pot rests on the reinforcing members as described below. This results in stability of the pot on the potholder. Where reinforcing members are not present, there is created a seal between the base of the pot and the burner device to retain heat applied to the base of the pot. In such embodiments, it may be necessary to have air inlet holes in the firetube so that the combustion reaction is not suffocated. In embodiments, the potholder comprises reinforcing members configured to provide structural strength to the potholder. For example, the potholder comprises a plurality of radial strips, such as radial strips. In embodiments, the radial strips are evenly spaced around the circumference of the potholder. In embodiments the strips are unevenly spaced. In some such embodiments, the strips are arranged symmetrically about a plane (e.g., a pair of closely-spaced strips on one half of the potholder, and a symmetric pair of strips on the other half). The number of strips can vary and may be between 3-10 or 3-6, or may be 3, 4, 5, 6, 7, 8, 9, or 10, or more than 10. The strips may be of any suitable width and thickness provided that they impart the desired amount of structural reinforcement. For example, the strips can be less than or equal to 0.25, 0.5, 0.75, or 1 inch in width, and can be less than or equal to 10, 8, 7, 5, 4, 3, 2, 1, or 0.5 mm in thickness. The strips may be made of the same material as the potholder or may be made of a different material. In addition or in the alternative to radial strips, the reinforcing members may further comprise circumferential members (e.g., rings or spirals) of various widths and thicknesses. In embodiments, reinforcing members are not present and the potholder is composed of a material and with dimensions sufficient to operate without reinforcement.

In embodiments, the reinforcing members serve a further purpose of providing pot grips. As pot grips, the reinforcing members provide resistance toward slippage of a pot resting within the potholder. The reinforcing members can be made of a material that provides greater friction, and/or they can be shaped so as to provide such resistance. For example, in embodiments, the reinforcing members have notches along their length (e.g., a staircase configuration) such that a pot can rest within the notches of the reinforcing members.

As mentioned, the reinforcing members have a thickness, and in embodiments, the thickness of the reinforcing members is sufficient to ensure that there is space between a pot resting on the reinforcing members in the potholder and the potholder surface (e.g., the surface of the cone-shaped potholder). Such space, in embodiments, allows for ventilation (airflow) and heat transfer around a pot during use. Thus, the reinforcing members can serve the additional purpose of elevating the pot away from the surface of the potholder. Airflow can be useful so as to ensure that the combustion reaction occurring within the firebox is not suffocated. Airflow can also be accomplished with air vents in the firetube to assist in oxygenating the flame for more complete combustion. Combinations of these embodiments can be used as well. In embodiments, the potholder comprises elevating members that are not structural (i.e., do not provide reinforcement to the potholder) but still elevate a pot away from the surface of the potholder so that airflow is allowed.

The pots which the potholder is configured to support may be of any desired size, although will typically be in the volume range 0.5-200, 0.5-150, 0.5-125, 0.5-100, 0.5-75, 0.5-50, 0,5-25, 0.5-20, 0.5-15, 0.5-10, or 1-8, or 1-6 quarts. The potholder can be configured to support any pot within such ranges of pot sizes, or can be configured to support a specific pot size.

The burner device comprises a flame hole disposed in the potholder. The flame hole is configured to allow flames and/or hot gases and/or radiant heat emanating from the firebox to pass through the potholder. The flame hole is located at the apex of the cone-shaped potholder (accordingly, the potholder can be referred to as a "truncated cone"). Where the potholder is flat, the flame hole is disposed centrally. The flame hole can be any suitable size provided that it is not so large as to compromise the structural stability of the potholder or to allow standard sized pots to fall through the flame hole, and provided that it is not so small as to prevent or significantly impede heat transfer from the firebox. In embodiments the flame hole diameter is selected to match the diameter of the riser section of the firetube. The flame hole size can be selected base on the size of the potholder. In embodiments, the flame hole is circular and has a diameter in the range 1-60, 1-50, 1-40, 1-30, 1-20, 1-15, 1-12, 1-10, 1-8, 2-8, or 2-6 inches, or is greater than or equal to 1, 2, 3, 4, 5, 8, 10, 12, 15, 20, 30, 40, or 50, inches or is less than or equal to 60, 50, 40, 30, 20, 15, 12, 10, 8, 7, 6, 5, 4, or 3 inches. The flame hole can be any shape (e.g., square, irregular, etc.), and these dimensions equally apply to the largest dimension of the flame hole. The flame hole diameter (and equivalently, in this particular embodiment, the diameter of the riser section of the firetube) is shown as label 17 in FIG. 1A (dashed lines used to indicate the specific measurement).

As described herein in more detail, a plurality of potholders and corresponding flame holes may be present for multi-burner devices. Throughout this specification, unless indicated otherwise, reference to "the burner device" is meant to include multi- burner devices as well as single-burner devices.

The burner device comprises a firebox. The firebox is a space for generating heat via combusting solid fuel, and for collecting combustion waste (e.g., ashes). Thus the firebox contains an internal volume configured to allow a combustion reaction to occur. The firebox is in communication with the flame hole (via the firetube as described herein) and therefore delivers heat to the flame hole. The firebox is configured to receive solid fuel, to provide a space for combustion of the solid fuel, and to release heat energy. The firebox comprises a floor panel, sidewalls connected to the floor panel, and an optional upward facing panel connected to the sidewalls. The firebox may be any suitable three-dimensional shape such as cylindrical (i.e., containing only one sidewall), triangular prism (i.e., containing three sidewalls), cubic or cuboid (i.e., containing four sidewalls), etc. The sidewalls, floor panel, and top panel (when present) define the internal volume within which combustion occurs during operation. The firebox is made from a heat resistant material such as steel, iron, aluminum, or the like.

The firebox comprises a fuel inlet configured to receive solid fuel and also configured to act as an air inlet for fueling a combustion reaction within the firebox. In an embodiment, the fuel inlet is a hole in the top panel (i.e., the upward facing panel) of the firebox. In embodiments, the entire top panel of the firebox is absent and serves as the fuel inlet. The fuel inlet is configured to allow elongate pieces of solid fuel such as twigs and branches to stand partially or substantially vertical, i.e., by resting one end of the elongate solid fuel on the floor panel of the firebox. Thus, in embodiments, the fuel inlet is configured to receive solid fuel in a substantially vertical orientation. In this way, a portion of the elongate solid fuel can extend out of the fuel inlet of the firebox. Such portion of the elongate solid fuel is in position to enter the firebox but does not burn while outside of the firebox. As the portion of the fuel within the firebox is consumed by combustion, it disintegrates, thereby making space within the firebox for additional fuel. The portion of the elongate solid fuel extending out of the firebox then is able to descend into the firebox. A support bar may be disposed on or near the firebox that is configured to support very long pieces of solid fuel.

The firebox comprises a heat outlet configured to allow heat (i.e., radiant heat, heated gases, etc.) to escape from the firebox. The heat outlet is a hole disposed in a sidewall of the firebox. In operation, the sidewalls stand substantially vertically; the heat outlet is also therefore vertical, such that heat can escape substantially horizontally from the firebox. By "substantially horizontally" is meant to include an angle of greater than or equal to 75, 80, and 85° relative to the orientation of the fuel inlet (which is typically a horizontal hole in the firebox). Thus if the firebox comprises a horizontal (relative to the ground upon which the device sits) hole for the fuel inlet, then the heat outlet is substantially vertical to the ground and heat escapes the firebox at

substantially a horizontal direction. The heat outlet may, in embodiments, be covered with a screen or mesh to prevent solid materials from exiting the firebox. As described in more detail herein, the firebox may comprise a plurality of heat outlets (i.e., a plurality of holes disposed in the sidewalls) for multi-burner devices. In such multi- burner devices with a plurality of heat outlets, one ore all of the heat outlets may comprise a built-in door (or the equivalent, such as louvers) that allows the user to close the heat outlet when the corresponding potholder is not in use. Alternatively, a sliding door (i.e., a panel not built into the device but inserted as a separate item) can be inserted to block the heat outlet and separate the firebox from the fire tube not in use. In such embodiments, the firebox can comprise guide rails or other members that help to position the sliding door.

The firebox may further contain a removable ashtray at the bottom, configured to catch ashes and for convenient cleaning of the firebox. In embodiments the ashtray has a handle (e.g., a heat-resistant handle or a handle positioned so as not to accumulate excessive heat) accessible to the user to allow cleaning of ashes from the firebox, e.g., even when the firebox is in use. In embodiments the firebox has one or more holes (or a mesh) in the bottom face such that ashes can fall completely out of the firebox.

In embodiments, the firebox comprises a removable insert. The removable insert is shaped similarly to the firebox but smaller such that it fits within the firebox. The removable insert is configured to retain ashes and other waste products for easier removal from the device. The removable insert contains a heat outlet (or a plurality of heat outlets) that aligns with the heat outlet(s) of the firebox so as not to impede escape of heat from the firebox. In embodiments where a removable insert is present, the firebox may comprise an upward facing panel (e.g., a lip around the top edge of the firebox) that frames the removable insert and prevents the removable insert from exhibiting substantial horizontal movement. The removable insert also contains a fuel inlet at the top and may in some embodiments lack a top panel such that the entire top side of the removable insert is absent and is used as the fuel inlet. The removable insert may have an attached handle that allows the removable insert to be conveniently lifted out of the firebox, such as for cleaning. The handle maybe attached in any convenient place, such as to the top edge of the removable insert. Where a removable insert is present, it will be appreciated that fuel is added not to the firebox directly, but to the removable insert which is disposed in the firebox. Nevertheless, throughout this disclosure such embodiments still refer to fuel as being added to the firebox (and/or as being added to the removable insert).

The removable insert may be constructed entirely from a solid material such as plate steel, or may have one or more panels of mesh (or one or more panel may be partially mesh and partially solid). In embodiments, the panels may be made of solid material comprising one or more holes cut from the material. In embodiments, the mesh and/or holes may be present on the bottom panel of the removable insert, such that ashes created inside the removable insert are able to fall through the bottom panel and into the firebox (e.g., the bottom panel of the firebox or a removable ashtray disposed below the removable insert).

The size of the firebox can vary according to the overall size of the burner device, the amount of fuel that is desired to be in the firebox, and other factors. In

embodiments, each of the length, width, and height dimensions are independently in the range of 2-70, 3-60, 3-50, 3-40, 3-30, 3-20, or 3-10 inches, or can be greater than or equal to 2, 3, 5, 8, 10, 15, 20, 25, 30, 0, 50, or 60 inches, or less than or equal to 70, 50, 45, 40, 35, 30, 24, 20, 15, 12, or 10 inches. The firebox may be a cube (i.e., same length, width, and height measurements) or may be a cuboid (e.g., larger in height than in width/length).

The size of the removable insert can vary but is smaller than the firebox such that the removable insert can fit within the firebox. For example the length and width dimensions of the removable insert may be in the range 1-20, 1-15, 1-10, or 1-5% less than those of the firebox, or may be 1, 3, 5, 10, 15, or 20% less than those of the firebox. Where insulation is present between the firebox and the removable insert, it will be appreciated that the dimensions of the removable insert will be determined to account for such insulation. Where the firebox has a hole in the bottom plate, the hole is not so large that the removable insert falls through. That is, the bottom plate of the firebox has at least a lip or ledge upon which the removable insert can rest.

The removable insert may comprise a lid. Such lid can be hinged along one edge so as to be capable of being opened/closed. In embodiments, the lid is configured with a stop such that the lid cannot completely close - e.g., a gap is always present between a portion of the lid and the upper edge of the removable insert. The lid can have various preset opening positions that enable various amounts of air to enter the removable insert.

The burner device comprises a firetube configured to transmit heat (i.e., to enable heat to transfer] from the firebox to the potholder via. The firetube intersects a sidewall of firebox such that the firetube is in communication with the heat outlet of the firebox, and further intersects the potholder such that the firetube is in communication with the flame hole at the apex of the potholder. Thus the firetube provides a conduit for heat transfer (i.e., transfer of heated gases, or radiant heat] from the firebox to the potholder.

The firetube comprises a riser section configured to be substantially vertical and comprising a top and a base, wherein the top of the riser section is in communication with the flame hole. In embodiments, the top of the riser section is wider in diameter than the flame hole and therefore envelops the flame hole. In embodiments, the top of the riser section is the same diameter as the flame hole. The riser section may be of uniform diameter throughout, or may have an increasing or decreasing diameter from base to top. The length of the riser section influences the height of the potholder above the base of the burner device. In embodiments, the riser section can have a length between 3-50, 3-40, 3-30, 6-24, 6-20, or 10-20 inches, or can be greater than or equal to 6, 8, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, or 45 inches, or less than or equal to 50, 45, 40, 35, 30, 24, 20, 16, 14, 12, or 10 inches. Furthermore the riser section can have a diameter that is in the range 1-60, 1-50, 1-40, 1-30, 1-20, 1-15, 1-12, 1-10, 1-8, 2-8, or 2- 6 inches, or is greater than or equal to 1, 2, 3, 4, 5, 8, 10, 12, 15, 20, 30, 40, or 50 inches or is less than or equal to 60, 50, 40, 30, 20, 15, 12, 10, 8, 7, 6, 5, 4, or 3 inches. In embodiments, the diameter of the riser section is constant throughout.

The firetube further comprises a transfer section configured to be substantially horizontal. One end of the transfer section intersects and communicates with the riser section at the base of the riser section. The other end of the transfer section intersects the firebox and is in communication with the heat outlet of the firebox. The transfer section may be of uniform diameter throughout, or may have an increasing or decreasing diameter from the firebox heat outlet to the riser section. The length of the transfer section influences the distance between the firebox and the riser section of the firetube. In embodiments, the transfer section can have a length between 1-70, 2-60, 2- 50, 2-40, 2-30, 2-30, 3-12, 4-10, or 4-8 inches, or can be greater than or equal to 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 50, or 60 inches, or less than or equal to 70, 60, 50, 40, 30, 20, 15, 12, 10, 9, 8, 7, 6, 5, or 4 inches. Furthermore the transfer section can have a diameter that is in the range 1-60, 1-50, 1-40, 1-30, 1-20, 1-15, 1-12, 1-10, 1-8, 2-8, or 2-6 inches, or is greater than or equal to 1, 2, 3, 4, 5, 8, 10, 12, 15, 20, 30, 40, or 50 inches or is less than or equal to 60, 50, 40, 30, 20, 15, 12, 10, 8, 7, 6, 5, 4, or 3 inches. In embodiments, the diameter of the transfer section is equal to the diameter of the riser section. In embodiments, the diameter of the transfer section is constant throughout.

In embodiments, the transfer section contains a plurality of air inlet holes along at least a portion of the transfer section. The air inlet holes are configured to provide an auxiliary air input to the combustion reaction occurring within the firebox of the burner device (the main air inlet being the fuel inlet). The portion containing the air inlet holes, in embodiments, is at the end of the transfer section that intersects the firebox, and is therefore close in proximity to the firebox. The number and distribution of air inlet holes can vary. For example the air inlet holes are distributed in rows and within any row they are distributed evenly along the circumference of the transfer section. In embodiments, the air inlet holes can be distributed along the entire length of the transfer section. In embodiments, the riser section can also comprise air inlet holes, along a portion or along the entire length of the riser section.

The transfer section and the riser section intersect in such a way as to provide a continuous transfer conduit for heat transfer from the firebox to the potholder. The two sections may be welded together, or in embodiments, the firetube is a single tube with a bend such that there is no seam to distinguish the two sections. In embodiments the firetube is circular in cross-section throughout the length of the firetube, although other configurations (e.g., square tubes, etc.) are possible and within the scope of the invention.

The combination of the firetube and the firebox forms a "J-tube" design. The J- tube is so named because a side profile of the riser section, the transfer section, and the firebox forms a J-shape. The J-shape is even more pronounced when elongate pieces of solid fuel are added to the firebox, since the solid fuel stands upright within the firebox. This contrasts with traditional L-tube designs for burner devices. In L-tube designs, there is no firebox and the solid fuel lays flat on the ground (horizontally) rather than on end (vertically). As described herein in more detail, a plurality of firetubes may be present for multi-burner devices, but each firetube connects to a single firebox (i.e., one firebox has multiple connections to the various firetubes). Thus, in embodiments, the burner device comprises a plurality of J-tubes, with each J-tube sharing a common firebox but having a separate potholder.

The burner device may comprise one or more insulation elements to minimize heat loss. Heat loss occurs where there is heat generated within the firebox that doesn't reach the flame hole of the potholder. Heat can be lost through the sidewalls or floor of the firebox, or through the firetube. Heat can be lost through the wall or grating of the potholder. The insulation elements are configured to prevent such losses.

In embodiments, the insulation element comprises a housing (i.e., a rigid housing) enclosing the firebox and a section of the firetube (e.g., the riser section, or the transfer section, or a portion of the transfer section, or a portion of the riser section). In embodiments, the insulation element comprises a housing enclosing the entire firetube and the firebox. In embodiments, the insulation element comprises a housing that is an outer insulating tube surrounding the riser section and at least a portion of the transfer section of the firetube. The housing can be metal or any other structurally- rigid material, and can form a gap between the housing and the firetube and/or firebox. The insulation element further comprises an insulating material that is heat-resistant and heat-insulating (i.e., non-conducting) and can be made, for example, from cement, vermiculite, asbestos, fiberglass, dirt, cotton or any fabric material (e.g., a blanket), or combinations thereof. The insulating material is disposed within the gap between the housing and the firetube and/or firebox. In embodiments, such gap is partially or completely left vacant of solid material; in such embodiments air is an insulating material within the gap. In embodiments, the insulation element does not comprise a housing (i.e., a rigid housing) but only has an insulating material such as a blanket or fiberglass covering.

In embodiments, the insulation element also functions as a structural element, providing structural support to the burner device and optionally allowing for attachment of a carrying handle or the like.

In embodiments, the burner device is not supplied with insulation, but has a wire mesh (e.g., chicken wire or the like) surrounding certain parts such as the firetube. The wire mesh can serve to support insulation that is applied after-market. For example, users may apply mud or other insulating material to the outside of the device, with the wire mesh providing support for such insulation. In embodiments, the burner device is portable. By "portable" is meant that the burner device can be carried from one location to another, such as carried by a single person (i.e., an average adult], or such as carried by 2-4 people. Accordingly, the device is configured to be portable such that it is not too heavy or too bulky to prevent being carried. Regarding weight, the single-burner device may be less than or equal to about 150, 100, 50, 25, 20, 15, 10, or 5 kg, or in the range 1-150, 1-25, or 2-20 kg. Also for example, the double-burner device may be in the range 2-200, 2-30, or 2-20 kg, or less than or equal to about 30, 25, 20, 15, 10, or 5 kg. The three-burner device may be in the range 3-200, 3-30, or 3-20 kg, or less than or equal to about 30, 25, 20, 15, 10, or 5 kg. The four-burner device may be in the range 3-200, -30, or 4-25 kg, or less than or equal to about 30, 25, 20, 15, 10, or 5 kg.

In embodiments, the burner device comprises a carrying handle to ease carrying the device. The carrying handle can be attached to any point(s] on the burner device provided that the attachment is sufficiently strong to enable the handle to support the weight of the device. For example, the carrying handle can be attached to the insulation element as described (e.g., the carrying handle can be attached to the housing portion of the insulation element]. For example, the carrying handle can be attached to an outer insulating tube (i.e., surrounding the riser section]. Other attachment points are within the scope of the invention and can be determined by one of skill in the art. In embodiments, the carrying handle is attached to the burner device near the firebox (e.g., to the insulation element surrounding the firebox] and is configured such that solid fuel, when extending vertically out of the firebox, rests against the carrying handle and does not fall over or out of the firebox.

The burner devices may comprise a plurality of potholders, such as 2, 3, or 4 potholders. Typically, devices with a plurality of potholders have a single firebox such that fuel is supplied and burned at only one location. The heat from the single firebox can be split and delivered to the plurality of potholders. Should one or more potholder not be required for cooking or heating, the heat outlet to that potholder can be closed as described herein, therefore concentrating the flame through the potholder(s] where the heat is desired and not wasting fuel/heat unnecessarily. Also typically, the number of heat outlets is equal to the number of potholders present, such that each potholder has a dedicated heat outlet directly removing heat from the firebox. Each heat outlet supplies heat to a separate firetube and each firetube provides heat to a separate potholder.

In an embodiment, a burner device comprises a second potholder configured to support a cooking pot; a second flame hole at the base of the second potholder; a second heat outlet separate from the first heat outlet and configured to allow heat to escape from the firebox; a second firetube configured to enable heat to transfer from the firebox to the second potholder via the second heat outlet, the second firetube comprising: a second riser section comprising a top and a base, wherein the top is in communication with the second flame hole; and a second transfer section intersecting the second riser section at its base and further in communication with the second heat outlet of the firebox. In an embodiment, the second potholder is a cone-shaped potholder. For burner devices with two potholders, the arrangement of the two potholders (and their respective firetubes) can be, in an embodiment, a linear arrangement with the potholders at opposite ends of the common firebox. Alternatively, the arrangement can be triangular, with the two potholders and the firebox forming the three corners of a triangle. The carrying handle, when present, is attached to the device at any convenient location such as in front of the firebox (e.g., connected to a housing surrounding the firebox and configured to support solid fuel placed within the firebox but extending out of the firebox).

In an embodiment, a burner device comprises a third potholder configured to support a cooking pot; a third flame hole at the base of the third potholder; a third heat outlet separate from the first and second heat outlets and configured to allow heat to escape from the firebox; a third firetube configured to enable heat to transfer from the firebox to the third potholder via the third heat outlet, the third firetube comprising: a third riser section comprising a top and a base, wherein the top is in communication with the third flame hole; and a third transfer section intersecting the third riser section at its base and further in communication with the third heat outlet of the firebox. In an embodiment, the third potholder is a cone-shaped potholder. For burner devices with three potholders, the arrangement of the three potholders (and their respective firetubes) can be, in an embodiment, a triangular arrangement with the potholders at the three corners of a triangle and surrounding the common firebox. In an embodiment, the triangle is equilateral, and the firebox is in the center of the triangle. In an embodiment, the triangle is not equilateral but, rather, the firebox is in a linear relationship and positioned between two of the potholders with the third potholder offset and forming the third point of the triangle.

In an embodiment, a burner device comprises a fourth potholder configured to support a cooking pot; a fourth flame hole at the base of the fourth potholder; a fourth heat outlet separate from the first and second and third heat outlets and configured to allow heat to escape from the firebox; a fourth firetube configured to enable heat to transfer from the firebox to the fourth potholder via the fourth heat outlet, the fourth firetube comprising: a fourth riser section comprising a top and a base, wherein the top is in communication with the fourth flame hole; and a fourth transfer section intersecting the fourth riser section at its base and further in communication with the fourth heat outlet of the firebox. In an embodiment, the fourth potholder is a cone- shaped potholder. For burner devices with four potholders, the arrangement of the four potholders [and their respective firetubes) can be, in an embodiment, a square, with the common firebox in the center of the square.

Referring now to FIG. 1A and FIG. IB, there is provided a cross section and isometric drawing, respectively, of single burner device 100 according to one embodiment of the invention. Cone-shaped potholder 10 comprises a plurality of pot grips 11 and flame hole 12. Cone-shaped potholder 10 attaches to a riser section (not shown} of firetube 20. The riser section connects to transfer section 22 of firetube 20 and firetube 20 forms a continuous conduit between cone-shaped potholder 10 and firebox 30. Transfer section 22 connects to firebox 30 via heat outlet 32. Firebox 30 contains removable insert 31. Transfer section 22 contains a plurality of air inlet holes 23. Surrounding a portion of firetube 20 (specifically, the riser section and a portion of transfer section 22) is insulation member 40. Insulation member 40 comprises insulating material (not shown) between insulation member 40 and firetube 20. In operation, solid fuel is added to firebox 30 via fuel inlet 32. As mentioned previously, due to the presence of removable insert 31, the fuel is not added directly to firebox 30 but rather is added to removable insert 31, which is disposed within firebox 30.

Removable insert 31 also contains fuel inlet 33. Fuel that is added to firebox 30 stands vertically and extends out of the firebox 30, but is continuously fed into firebox 30 to replenish burning fuel within internal volume 33 of firebox 30.

Referring now to FIG. 2, there is provided an isometric drawing of double burner device 200 according to one embodiment of the invention. The device contains cone- shaped potholders 10a and 10b, firebox 30, and firetubes 20a and 20b therebetween. A removable insert is not shown in FIG. 2 although can be used if desired. Firebox 30 does not contain a top panel although one can be present if desired. Firetubes 20a and 20b are surrounded in part by insulation member 40a and 40b, respectively. Firebox 30 contains heat outlets 32a and 32b, which connect to firetubes 20a and 20b respectively. Although not shown, pot grips may be used in the potholders 10a and 10b.

Referring now to FIG. 3, there is provided an isometric drawing of three-burner device 300 according to one embodiment of the invention. The device is arranged such that firebox 30 is in a linear relationship with cone-shaped potholders 10a and 10b, and cone-shaped potholder 10c is offset. Thus, cone-shaped potholders 10a, 10b, and 10c form a non-equilateral triangle. Firebox 30 contains three heat outlets 32a, 32b, and 32c (although 32b is not visible in the drawing), which connect to firetubes 20a, 20b, and 20c, respectively. Although not shown, pot grips may be used in the potholders 10a, 10b, and 10c.

Referring now to FIG. 4, there is provided an isometric representation of a four- burner device according to one embodiment of the invention. The device is arranged such that firebox 30 (which contains four heat outlets, although only two are visible in the drawing) is central to four J-tubes containing cone-shaped potholders 10a, 10b, 10c, and lOd. Although not shown, pot grips may be used in the potholders 10a, 10b, 10c, and lOd.

In an aspect, there is provided a method of use of the burner devices described herein. In an embodiment, the method is for providing heat to a cooking pot, and the method comprises placing a pot on the potholder of the device, feeding solid fuel to the firebox, and combusting the fuel in the firebox, wherein the combusting produces heat and at least a portion of the heat is transferred through the firetube to the pot on the potholder. In an embodiment, the method is for providing heat to a space, and the method comprises feeding solid fuel to the firebox, and combusting the fuel in the firebox, wherein the combusting produces heat and at least a portion of the heat is transferred through the firetube, through the fire hole, and into the space within which the device is located. Other uses for the disclosed devices will be apparent to those of ordinary skill in the art.

The burner devices are relatively highly efficient, meaning that a high percentage of heat generated by the combustion of solid fuel is applied to a pot on the potholder(s). In embodiments, the burner device is equal to or greater than 20, 25, 30, 35, or 40% efficient, or within the range 20-50%, or 20-40%, or 30-40% efficient (i.e., such percentage of generated heat is applied to a pot). In embodiments, approximately 37% of the produced heat is applied to a pot, or the burner device is 37% efficient.

It is to be understood that while the invention has been described in conjunction with the preferred specific embodiments thereof, the foregoing description is intended to illustrate and not limit the scope of the invention. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention, and further that other aspects, advantages and modifications will be apparent to those skilled in the art to which the invention pertains. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. Any combination of the embodiments described herein is intended to be part of the invention, as if such combinations had been laboriously set forth in this disclosure.

Claims

What is claimed is:

1. A portable burner device comprising:

a cone-shaped potholder configured to support a cooking pot;

a flame hole at an apex of the cone-shaped potholder;

a firebox comprising a heat outlet configured to allow heat to escape from the firebox and a fuel inlet configured to receive solid fuel;

a firetube configured to enable heat to transfer from the firebox to the cone-shaped potholder via the heat outlet, the firetube comprising:

a riser section comprising a top and a base, wherein the top is in communication with the flame hole; and

a transfer section intersecting the riser section at its base and further in communication with the heat outlet of the firebox.

2. The device of claim 1, further comprising an outer insulating tube surrounding the riser section and at least a portion of the transfer section of the firetube.

3. The device of claim 1, wherein the firebox further comprises a removable insert configured to retain ashes for removal from the device, and wherein the fuel inlet is configured to receive solid fuel in a substantially vertical orientation, and wherein the heat outlet is configured to allow heat to escape substantially horizontally from the firebox.

4. The device of claim 1, wherein the firetube comprises air inlet holes along at least a portion of the transfer section.

5. The device of claim 1, further comprising a plurality of reinforcing members disposed in the cone-shaped potholder.

6. The device of claim 1, further comprising an outer insulating tube surrounding the riser section and a carrying handle attached to the outer insulating tube.

7. The device of claim 1, further comprising a housing enclosing the firebox and transfer section of the firetube.

8. The device of claim 1, further comprising:

a second cone-shaped potholder configured to support a cooking pot;

a second flame hole at the apex of the second cone-shaped potholder;

a second heat outlet separate from the first heat outlet and configured to allow heat to escape from the firebox;

a second firetube configured to enable heat to transfer from the firebox to the second cone-shaped potholder via the second heat outlet, the second firetube comprising: a second riser section comprising a top and a base, wherein the top is in communication with the second flame hole; and

a second transfer section intersecting the second riser section at its base and further in communication with the second heat outlet of the firebox.

9. The device of claim 8, further comprising:

a third cone-shaped potholder configured to support a cooking pot;

a third flame hole at the apex of the third cone-shaped potholder;

a third heat outlet separate from the first and second heat outlets and configured to allow heat to escape from the firebox;

a third firetube configured to enable heat to transfer from the firebox to the third cone- shaped potholder via the third heat outlet, the third firetube comprising:

a third riser section comprising a top and a base, wherein the top is in communication with the third flame hole; and

a third transfer section intersecting the third riser section at its base and further in communication with the third heat outlet of the firebox.

10. A portable burner device comprising:

a first potholder configured to support a cooking pot and comprising a first flame hole disposed centrally;

a second potholder configured to support a cooking pot and comprising a second flame hole disposed centrally;

a firebox comprising: a first heat outlet and a second heat outlet, the first and second heat outlets configured to allow heat to escape from the firebox; and

a fuel inlet configured to receive solid fuel;

a first firetube configured to enable heat to transfer from the firebox to the first potholder via the first heat outlet, the firetube comprising:

a riser section comprising a top and a base, wherein the top is in communication with the flame hole;

a transfer section intersecting the riser section at its base and further in communication with the first heat outlet of the firebox;

a second firetube configured to enable heat to transfer from the firebox to the second potholder via the second heat outlet, the firetube comprising:

a second riser section comprising a top and a base, wherein the top is in communication with the flame hole; and

a transfer section intersecting the riser section at its base and further in communication with the second heat outlet of the firebox.