Combustible Fuel Burning Fire Pit

This application is a continuation of U.S. application Ser. No. 18/924,817, filed Oct. 23, 2024, titled “Combustible Fuel Burning Fire Pit,” which is a continuation of U.S. application Ser. No. 18/626,771, now U.S. Pat. No. 12,209,751, filed Apr. 4, 2024, titled “Combustible Fuel Burning Fire Pit,” which is a continuation of U.S. application Ser. No. 18/389,667, now U.S. Pat. No. 11,953,207, filed Dec. 19, 2023, titled “Combustible Fuel Burning Fire Pit,” which is a continuation of U.S. application Ser. No. 17/169,269, now U.S. Pat. No. 11,879,641, filed Feb. 5, 2021, titled “Combustible Fuel Burning Fire Pit with Removable Fire Grate and Ash Pan,” which are each incorporated herein in their entireties.

The subject matter described herein relates to a combustible fuel burning fire pit with a removable fire grate and ash pan. The fire pit has particular but not exclusive utility for portable back yard firepits.

Portable wood burning stoves are used in camping for heat and cooking. Similarly, large portable firepits are used for example in residential back yards for recreation, to provide outdoor heat, and to support limited cooking such as marshmallow roasting.

Large firepits are a type of stove that is generally fueled by piles of logs, whereas portable wood stoves may be fueled by twigs and sticks. A fire grate may therefore be used within the fire pit to support this fuel during combustion. Ash may fall through the fire grate into the bottom of the fire pit structure. Removing this ash from the structure may require rolling or inverting the structure—an operation that may be strenuous and/or inconvenient for many users. Cleaning the fire grate, and the fire pit structure beneath the fire grate, may also be challenging.

It is therefore to be appreciated that such commonly used firepits could be improved by simplifying cleaning and ash removal, among others. Accordingly, a need exists for firepits that address the forgoing and other concerns.

The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded as subject matter by which the scope of the disclosure is to be bound.

Disclosed is a wood burning fire pit with removable fire grate and ash pan. The fire pit disclosed herein has particular, but not exclusive, utility for portable firepits.

One general aspect includes a fire pit with a burn chamber defined by an inwardly facing surface and a bottom; a removable fire grate disposed within the burn chamber and disposed to support combustible fuel for burning, the removable fire grate including: a plurality of holes sized to permit passage of ash from the combustible fuel; and at least one grip feature sized and shaped to permit a user to remove the removable fire grate from the fire pit by lifting the removable fire grate vertically through the burn chamber. The fire pit also includes a removable pan disposed within the burn chamber and beneath the removable fire grate, the removable pan including: a side wall and a bottom, and at least one grippable surface configured to permit the user to remove the removable pan from the fire pit by lifting the removable pan vertically through the burn chamber.

Implementations may include one or more of the following features. In some embodiments, at least one of the removable fire grate or the removable pan includes a generally circular shape, a width of the removeable fire grate being greater than a width of the removeable pan. In some embodiments, the removable fire grate includes a dome-shaped portion including a spherical section with a radius of curvature larger than one-half of a width of the removable fire grate. In some embodiments, the removable pan includes at least two downward-projecting feet, where the at least two downward-projecting feet form an air gap beneath the bottom of the removable pan. In some embodiments, the surface includes at least raised or lowered positioning feature sized and shaped to receive at least a portion of the at least two downward-projecting feet. In some embodiments, a diameter of the removable pan is less than a diameter of the burn chamber, such that an air gap is formed between the side wall of the removable pan and an inner wall of the burn chamber. In some embodiments, a volume of the removable pan is determined at least in part by the diameter of the removable pan and a height of the side wall of the removable pan. In some embodiments, the fire pit further includes: an outer wall; and an inner wall spaced from the outer wall by a gap, the inner wall forming the burn chamber. In some embodiments, the removable pan includes at least one handle. In some embodiments, the removable pan includes at least one ventilation hole. In some embodiments, the inwardly facing surface and the bottom are devoid of user access openings to the pan. In some embodiments, the raised central feature includes a cone or tower. In some embodiments, the shape of the removable fire grate is configured to enable production by stamping a flat blank of metallic material.

One general aspect includes a removable fire grate for a combustion fire pit. The removable fire grate includes a domed shape having a center and a perimeter, where the center is higher than the perimeter; a plurality of radial stiffening ribs extending away from the perimeter and toward the center, at least one circumferential stiffening ring extending at least partially about the center, a plurality of ventilation holes between the center and the perimeter, and at least one grip feature sized and shaped to permit a user to remove the removable fire grate from the combustion fire pit by lifting the removable fire grate vertically.

One general aspect includes a removable ash pan for a combustion fire pit. The removable ash pan includes a side wall; a bottom; an ash-storing capacity determined at least in part by a height of the side wall and width of the bottom; at least one grippable surface configured to permit a user to remove the removable ash pan from the combustion fire pit by lifting the removable ash pan vertically; and at least two downward-projecting feet at the bottom, where the at least two downward-projecting feet form an air gap beneath the bottom, where an outer width of the removable ash pan is less than an inner width of an inner wall of the combustion fire pit, such that an air gap is formed between the side wall of the removable ash pan and the inner wall of the combustion fire pit.

Implementations may include one or more of the following features. In some embodiments, the at least two downward-projecting feet are sized and shaped to be received by one or more positioning features disposed within the combustion fire pit beneath the removable ash pan. In some embodiments, the shape of the removable ash pan is configured to enable production by stamping a flat blank of metallic material.

One general aspect includes a system for burning a solid fuel to produce heat. The system includes an inner wall having a lower portion and an upper portion; an outer wall having a lower portion and an upper portion; an air-filled space between the inner wall and the outer wall; a burn chamber formed by the inner wall; a combustion area situated within the burn chamber; at least one ventilation hole within the upper portion of the inner wall; at least one ventilation hole within the lower portion of the outer wall; a removable fire grate disposed within the combustion area and configured to support the solid fuel, the removable fire grate including: a domed shape having a center and a perimeter, where the center is higher than the perimeter; a plurality of ventilation holes between the center and the perimeter; and at least one grip feature sized and shaped to permit a user to remove the removable fire grate from the burn chamber by lifting the removable fire grate vertically through the burn chamber. The system also includes a removable ash pan disposed within the burn chamber beneath the removable fire grate, the removable ash pan including: a side wall; a bottom; an ash-storing capacity determined at least in part by a height and diameter of the side wall; at least one grippable surface configured to permit the user to remove the removable ash pan from the burn chamber by lifting the removable ash pan vertically through the burn chamber; and at least two downward-projecting feet, where the at least two downward-projecting feet form an air gap beneath the bottom of the removable ash pan, where an outer diameter of the removable ash pan is less than an inner diameter of the inner wall, such that an air gap is formed between the side wall of the removable ash pan and the inner wall, where the at least two downward-projecting feet are sized and shaped to be received by one or more positioning features disposed within the burn chamber beneath the removable ash pan.

In some embodiments, the removable ash pan is configured to receive, through the plurality of ventilation holes of the removable fire grate, ash produced by the burning of the solid fuel.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. A more extensive presentation of features, details, utilities, and advantages of the fire grate, as defined in the claims, is provided in the following written description of various embodiments of the disclosure and illustrated in the accompanying drawings.

In accordance with at least one embodiment of the present disclosure, a fire pit is provided which includes novel structural features to permit easy removal and cleaning of a fire grate and ash pan. These features provide the necessary functional performance to support combustion of potentially heavy fuel loads at high temperature, while permitting a relatively low weight for the fire pit structure. The disclosed fire pit also includes air flow features conducive to thorough combustion of fuel, which leads to greater heat generation and substantially reduced smoke. Wood or other combustible solid fuel is supported by the fire grate during combustion. Any ash generated by the combustion falls through the fire grate and into an ash pan. To facilitate cleaning and ash removal, both the fire grate and the ash pan may be lifted vertically out of the fire pit structure. Ash may then be dumped out of the ash pan (e.g., into a trash receptacle), and optionally the ash pan and/or fire grate may be cleaned (e.g., with a brush or garden hose). The ash pan and fire grate may then be replaced into the fire pit structure, such that the fire pit is again ready for use.

Disclosed is a fire pit with removable fire grate and ash pan. The fire pit disclosed herein has particular, but not exclusive, utility for portable back yard firepits.

For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It is nevertheless understood that no limitation to the scope of the disclosure is intended. Any alterations and further modifications to the described devices, systems, and methods, and any further application of the principles of the present disclosure are fully contemplated and included within the present disclosure as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one embodiment may be combined with the features, components, and/or steps described with respect to other embodiments of the present disclosure. For the sake of brevity, however, the numerous iterations of these combinations will not be described separately.

These descriptions are provided for exemplary purposes only, and should not be considered to limit the scope of the removable fire grate, removable ash pan, or fire pit. Certain features may be added, removed, or modified without departing from the spirit of the claimed subject matter.

is a cross-sectional view of an example combustion fire pit, such as a wood burning fire pitincluding a removable fire grateand removable ash pan, in accordance with at least one embodiment of the present disclosure. The fire gratesits within the fire pitand supports the weight of fuel(e.g., wooden logs and sticks) while permitting air flow through the fire grateand fire pitto facilitate combustion of the fuel. The fire grateis strong and stiff to bear the weight of firewood and other fuel, both at ambient temperatures and at operating temperatures, and may resist substantial warping or other substantial deformation despite prolonged and repeated exposure to the heat of combustion. In an example, operating temperatures may reach about 1350° F. (732° C.), while the temperature of the fire pit under ambient, non-operating conditions may vary from about −40° F. (−40° C.) to about 120° F. (49° C.). The removable fire gratemay also be lighter and have greater airflow than other fire grates of comparable size.

In the example embodiment of, the combustion fire pitincludes a top portion, a bottom portion, and a middle portion. The firepitfurther includes an inner wall or inner body, an outer wall or outer body, a connecting ringlocated in the top portionof the fire pitand attached to or formed as a single piece with the inner bodyand the outer body, and a cavity or burn chamberdefined by an inwardly facing surface of the inner body, within which the fire grateis positioned. The fire pitfurther includes a top lipattached to or formed as a single piece with either of the inner bodyor outer body. The fire pitfurther includes a plurality of outer ventilation holeslocated in the bottom portionof the outer body, and a plurality of inner ventilation holeslocated in the top portionof the inner body. In the middle portionof the fire pit, the inner bodyterminates in an upward-facing support lip or rolloverinto which the fire gratefits, or upon which the fire graterests.

The fire pitfurther includes a base plateattached to the outer body, a bracing traysupported by stands projecting upward from the base plate, and a removable ash pansupported by stands or feet projecting downward from the ash paninto a receiving feature of the bracing tray, such that the bracing tray is separated from the outer body by an air gap, the ash panis separated from the outer bodyby an air gap, and the inner body is separated from the outer body by an air gap. In an example, air gapsandare both about 50 mm, while air gapis about 100 mm, although other air gaps may be employed that have the disclosed, advantageous effect.

The cavity or burn chamberis in fluid communication with the air gapvia the inner ventilation holes, and with air gapsandvia the fire grate. The air gapsandare in fluid communication with ambient air via the outer ventilation holes, such that ambient air may be drawn in through the outer ventilation holes, heated by combustion of the fuel, and expelled through the cavity or burn chamberand inner ventilation holesto produce advantageous combustion of the fuel.

In an example, the fire grate, ash pan, and other structure of the firepitare made of stainless steel plates having a thickness within a range of between about 0.5 mm and about 2.5 mm thick. Some examples of the fire grate, ash pan, and the firepitare formed of 1.0 mm to 2.0 mm thick stainless steel, and one example is about 1.5 mm thick stainless steel. Both thicker and thinner materials are contemplated, including other metals. In an example, the fire grateweighs approximately 48 lb (21.8 kg), although weights of between about 9 oz and about 88 lb may be provided. In an example, during normal operation the fire gratesupports a nominal weight of 100 lb (45.4 kg), (although nominal capacities of between about 5 lb and about 190 lb may be provided), while the fire grate, or portions thereof, are heated to between about 700° F. (371° C.) and about 1350° F. (732° C.) by the combustion of the fuel, for a time period of between 1 and 12 hours, and also at ambient temperatures as low as −40° F. (−40° C.). In an example, during normal operation over a period of years, with repeated cycling (e.g., one hundred cycles) between ambient and operational temperatures, the fire grateexhibits little or no warping that would detrimentally affect its aesthetic appearance, its performance, or its fit within the firepit.

In an example, the fuelcombusts into ash, which falls through the fire grateinto the ash pan. To facilitate cleaning and ash removal, the fire gratecan be removed from the fire pitby lifting it vertically upward, in a direction parallel to axis, through the cavity or burn chamber. This permits user access to the ash pan, which can then also be removed from the fire pit by lifting vertically through the cavity or burn chamber. The ash panmay then be emptied and optionally cleaned. The fire gratemay also optionally be cleaned, and then the ash panand fire gratereturned into the fire pitas shown in.

The primary load carried by the fire grateis applied downward, in a direction parallel to axis, by the weight of the fuelpiled on the fire grate, which is supported by the upward-facing lip or rolloverof the inner body.

is an exploded, side view of the fire pitwith removable fire grate and ash pan, in accordance with at least one embodiment of the present disclosure. Visible are the inner body, outer body, fire grate, ash pan, bracing tray, and base plate.

is an exemplary representation of a fire gratefor a wood burning fire pit in accordance with at least one embodiment of the present disclosure. In the example shown in the figure, the fire grate is a circular, convex, ventilated dome-shaped structuresurrounded by a stiff outer ring. The outer ringincludes an outer rimwith a downward-facing lip or rolloverthat provides stiffness, that fits into the upward facing lip or rolloverof the inner bodyof the firepit, and makes it more difficult for the outer rimof the fire grateto dent, warp, or otherwise deform. The outer rimmay define the axis. In this example, the fire gratefurther includes a central hubthat is raised above the outer rim. The ventilated domereaches from the inner edgeof the stiff outer ringto the outer edge the central hub. The ventilated domeincludes a plurality of ventilation holes, and in some embodiments the stiff outer ringis devoid of ventilation holes.

The fire gratehas an outer diameter D, matched to an inner diameter of the inner body. The outer diameter Dmay be in a range of about 9 inches to 48 inches although other sizes larger and smaller are contemplated. The dome portionhas an outer diameter D, which is less than D. The outer diameter Dmay be in a range of about 1 inch to 9 inches smaller than diameter D, although other sizes larger and smaller are contemplated. In an example, the fire grateincludes 258 circular ventilation holes, each having a diameter of about 10 mm. Other numbers and sizes of holes could be used (e.g., 50-800 holes, each with a diameter of between 0.5 cm and 1.5 cm). While more holes and/or larger holes would mean better overall ventilation, it may mean less structural material and thus a weaker structure for both the ventilated dome portionand the fire grateoverall. Because better ventilation may result in higher combustion temperatures, the structure may weaken further due to a combination of heat softening and heat expansion. A weaker structure may have a reduced ability to support the weight of firewood or other fuel piled on top of it (see), and may be more prone to collapse or warping. Conversely, fewer holes and/or smaller holes may result in a stronger overall structure and better support for firewood or other fuel, it may also result in worse ventilation and thus a lower combustion temperature, less head output, and increased generation of smoke.

The fire gratein the example shown inmay further include a plurality of radial stiffening ribsthat reach from the outer stiffening ringto, or partway to, the central hub. In the example shown in, six stiffening ribsreach all the way to the central hub. Depending on the implementation, other lengths or numbers of stiffening ribscould be used, including some ribs of a first length and other ribs of a second or third length. It is noted that adding more radial stiffening ribsmay leave room for fewer ventilation holes, while removing radial stiffening ribsmay create a weaker, less stiff, structure that is more prone to crushing and/or warping.

In addition to the plurality of ventilation holes, the ventilated domeincludes a concentric stiffening ringthat provides additional strength, stiffness, and stability to the structure of the fire grate, both at ambient temperature and at operating temperatures when a fire is burning in the fire pitthat includes the fire grate (see). In some embodiments, the stiffening ringhas a taller profile than the stiffening ribs. In other embodiments, the fire gratecould include more than one stiffening ring. For example, some embodiments include between 2 and 5 stiffening rings. Even greater numbers of stiffening rings are contemplated. However, increasing the number of stiffening rings may reduce the number or size of the ventilation holes, with effects as described above, or else decrease the spacing between the ventilation holes, which may weaken the structure of the fire grate. In still other embodiments, the fire gratemay include no stiffening rings, which may result in a weaker, less stiff structure with more space available for ventilation holes. In some embodiments, the central hubis not present.

In an example, the hub, stiffening ribs, and stiffening ringare stamped or otherwise embossed into the material of the fire grate (e.g., stainless steel), although other fabrication methods may be employed. In an example, the dome portionis a spherical section with a radius of curvature larger than one-half of a width or diameter of the fire grate. In an example, the fire grateis formed from a flat, circular blank by a stamping process. In an example, the holesare also formed by the stamping process, although they may alternatively be produced by drilling, laser cutting, or other methods.

In some embodiments, one or more of the holesmay overlap with one or more of the stiffening ribs, or stiffening ring. However, in other embodiments the hole pattern, rib pattern, and ring pattern have been selected such that no holesoverlap with any of the ribs, or ring.

In the example shown in, the removable fire gratealso includes two grip features, shown in this example as handles. In other implementations, the grip features may be shaped to interface with a fire grate removal tool. As shown, the handles are formed as openings larger than the ventilation holes. In the implementation shown, each of the handles or openingsare sized and shaped to receive human fingers and thus to serve as handles for lifting the removable fire grateout of the fire pitthrough the cavity or burn chamber. The handlesmay be sized or shaped differently than shown herein, and may be of different number. For example, the fire grate may include one handle, three handles, or a larger number of handles.

is a perspective view of an example ash panand bottom portionof the bracing trayfor a wood burning fire pit, in accordance with at least one embodiment of the present disclosure. The ash panhas a diameter Dwhich is less than the diameter Dof the fire grate, and which may be comparable to the diameter Dof the ventilated dome portionof the fire grate. Diameter Dmay be in a range of about 7 inches to 47 inches, although larger and smaller sizes are contemplated. In some implementations, the diameter Dis in a range of about 10 inches to 22 inches. In some implementations, the ventilated portion of the fire grate (e.g., the ventilated dome portion, includes a width (e.g., a diameter) that is equal to or smaller than the width of the ash pan. Thus, when fuelcombusts to ash, the ashcan fall through the ventilation holesin the dome portionof the fire grateand then fall downward into the ash pan. The ash panhas an interior volume that determines how much ashit can hold before it needs to be emptied. The interior volume of the ash panis determined at least in part by the height H and diameter Dof the ash pan.

The ash panincludes a side walland bottom. The side wallincludes a top lip, which may for example be a rolled or folded lip. In the example shown in, the ash pan bottomincludes an upward-embossed central hub, three radial stiffening arms, and three downward-embossed feetdisposed at or near the outer edgeof the ash pan bottom. Other sizes, shapes, and numbers of feet May be used instead of or in addition to the three feet shown in. For example, some embodiments include only two feet, sized and shaped to provide stability for the removable ash pan, while other embodiments include four or more feet. The sizes and shapes of the central hub, radial stiffening arms, and feetmay differ from those shown in, and some embodiments may have different numbers of feetor stiffening arms, or may lack the huband/or stiffening armsaltogether.

When correctly placed in the fire pit, the ash panrests on the bottomof the bracing tray. The bracing tray bottomincludes a raised outer ringand a lowered inner ring, separated by a centering rim. The bracing tray bottomalso includes a ventilation opening, through which air can flow during combustion of the fuelin the fire pit. The feetof the ash panrest on the bracing tray bottomsuch that they are nested against the centering rim. This permits both the self-centering of the ash panwithin the fire pit, and the maintenance of air gapbetween the ash panand the bracing tray, with minimal effort or precision required on the part of the user.

In an example, the diameter Dof the ash pan is less than the diameter Dof the fire grate(and thus less than the inner diameter of the inner body) by an amount large enough to admit a user's fingers. The lipor side wallmay they form one or more grippable surfaces which enable the user to grasp the ash panand lift it vertically upward through the burn chamberof the fire pit, or else return it into the fire pitby lowering it vertically through the burn chamber.

In an example, because the central huband the radial stiffening armsincrease the strength and stiffness of the removable ash pan, the overall thickness (and thus, weight) of the ash pan can be reduced, without substantially increasing the risk of heat-related warping, or of denting or other damage occurring from handling of the ash pan. In an example, the removable ash panmay be produced quickly and at low cost by stamping a metal blank.

is cross-sectional side view of air flow through an example fire pit, in accordance with at least one embodiment of the present disclosure. Cold outside airis drawn inward through the ventilation holeslocated near the bottom of the outer body. A portion of this air then becomes cooling airwhich rises up between the inner bodyand the outer body, then exits into the burn chambervia ventilation holeslocated near the top of the inner body, where it exits the fire pit. Another, different portion of the cool outside airbecomes combustion air. Combustion airis drawn radially between the base plateand the bracing traytoward the center of the bracing tray, and then upward through the ventilation openingin the bracing tray bottom. The combustion airis then drawn radially outward along the bottom of the ash pan, then upward around the edges of the ash pan, then radially inward along the top of the ash pan. The combustion airis then drawn upward through the ventilation holes in the fire grateand into the burn chamber, where it can interact with combusting fuel.

A gapexists between the lip of the ash panand the side of the bracing tray. In some embodiments, this gapis large enough to admit human fingers, thus enabling a user to grab the ash pan when it is cool, and remove it from the fire pit. Arrow or axisshows the direction the fire grateand ash panmay be lifted, in order to remove them from the fire pit.

The flow of cooling airbetween the inner bodyand outer bodymay serve to cool both the inner bodyand outer body. The flow of combustion airtoward the ventilation openingof the bracing traymay serve to cool the base plateand bracing tray. The flow of combustion airbetween the bracing tray and ash panmay serve to cool both the bracing trayand the ash pan. Thus, the wall of the outer bodyis insulated by a layer of moving air, and the base plateis insulated by three separate layers of moving air. This enables the exterior portions of the fire pit(e.g., the outer bodyand the base plate) to be much cooler than the burn chamberor fire grate, thus improving the safety of the fire pit and decreasing the chance of accidental burning of people, animals, or objects that may contact the exterior of the fire pit.

Additionally, the large flow of airthrough the fire pit helps to ensure that the fuel(see) is well oxygenated and thus burns at high temperature. This in turn maximizes the heat generated by a given quantity of fuel, while simultaneously minimizing the amount of smoke generated by the combustion.

is a perspective view of another embodiment of an ash panfor a wood burning fire pit, in accordance with at least one embodiment of the present disclosure. Like the embodiment shown in, the ash panincludes a top lip, an upward-embossed central hub, three radial stiffening arms, and three downward-embossed feetdisposed at or near the outer edge of the ash pan bottom. When correctly placed in the fire pit, the ash panrests on the bottom of the bracing tray, such that the feetof the ash panare nested against a centering feature of the bracing tray. The sizes and shapes of the central hub, radial stiffening arms, and feetmay differ from those shown in, and some embodiments may have different numbers of feetor stiffening arms, or may lack the huband/or stiffening armsaltogether.

Unlike the embodiment shown in, the embodiment shown inincludes two formed handles, which are sized and shaped to admit human fingers between the handlesand the sides of the bracing tray. This permits a user to grab and lift the ash panwhen it is cool, and when the fire grate has been lifted out of the way.

is a perspective view of another embodiment of an ash panfor a wood burning fire pit, in accordance with at least one embodiment of the present disclosure. In the embodiment shown in, the ash pandoes not include feet that rest on the bottom of the bracing tray. Rather, the ash panincludes a lipdesigned to hang from a recessed ringin the rimof the bracing tray. In addition, a central feature, cone, or towerrises up from the baseof the ash pan, and includes a capthat may for example be used as a handle to lift the ash panout of the fire pit, or return the ash paninto the fire pit.

Since air cannot travel around the lipof the ash panwhile it is hanging from the bracing tray, ventilation holesare provided both in the side wallof the ash panand in the central tower. The size, shape, and positioning of the tower, cap, or ventilation holesmay be different than shown in. The number of ventilation holes may also be different, ranging from one ventilation hole to a large plurality of ventilation holes.

The removable ash pan provides a low-cost, lightweight, stampable, high-strength, high-stiffness, high-airflow structure that is readily removable from the fire pit for emptying and cleaning. Similarly, the removable fire grate advantageously provides a low-cost, lightweight, stampable, high-strength, high-stiffness, high-airflow structure that resists denting, warping, and other deformation while carrying heavy fuel loads at operating temperatures as high as about 1350° F. (732° C.), and while cycling repeatedly between ambient temperature and operating temperature.

A number of variations are possible on the examples and embodiments described hereinabove. For example, the fire grate, ash pan, or other components could be made of heavier-gauge material in order to support more weight, or of lighter gauge material in order to become lighter and more portable. The fire grate could be made in different sizes and/or with different degrees of curvature. The ash pan could be made in different sizes, and with different depths. Air gaps may be larger or smaller than shown herein, to optimize air flow through the fire pit, to minimize weight or volume of the fire pit, or for other reasons. The relative lengths, widths, and radii of different components could be different than presented herein. The fire grate, ash pan, or other components could be made by different processes, including casting, forging, sintering, milling, orD printing. They could be made of different metals, or of nonmetallic materials such as ceramics. The fire pit rim could be noncircular, including such possible shapes as ovals, rectangles, triangles, and rhombuses. The technology described herein may be used to burn firewood, wood chips or pellets, scrap lumber, paper, cardboard, coal, and other combustible materials. It may be employed for example in lamps, stoves, firepits, fireplaces, furnaces, forges, and boilers, and other combustion heaters. In some implementations, the fire grate, ash pan, or other components may comprise several pieces that collectively form a structure like that described herein.

The logical operations making up the embodiments of the technology described herein are referred to variously as operations, steps, objects, elements, components, or modules. Furthermore, it should be understood that these may occur or be performed in any order, unless explicitly claimed otherwise or a specific order is inherently necessitated by the claim language.