AU2011213993B2

AU2011213993B2 - Fuel feed system for a pellet fire

Info

Publication number: AU2011213993B2
Application number: AU2011213993A
Authority: AU
Inventors: James Alexander Bruce; Allan David Whitfield
Original assignee: Allans Sheetmetal And Engineering Services Ltd
Current assignee: ALLAN'S SHEETMETAL AND ENGINEERING SERVICES Ltd
Priority date: 2010-02-10
Filing date: 2011-01-31
Publication date: 2014-11-06
Anticipated expiration: 2031-01-31
Also published as: HUE046137T2; EP2534423A1; WO2011098932A1; NZ578968A; EP2534423A4; JP5780436B2; AU2011213993A1; EP2534423B1; JP2013519858A

Abstract

A fuel feed system for a pellet fire which includes conveying means within a casing, said casing including a plurality of inlet means distributed lengthwise along the casing and a plurality of outlet means distributed lengthwise along the casing, such that each inlet means is horizontally offset from the adjacent outlet means and wherein said conveying means is configured to move compressed fuel pellets from an inlet means to an adjacent outlet means; such that in use said fuel feed system is configured to form a plurality of overlapping piles of compressed fuel pellets in a burn pot of the pellet fire.

Description

WO 20111098932 PCT/IB2011/050405 TITLE: FUEL FEED SYSTEM FOR A PELLET FIRE Technical Field The present invention is a fuel feed system for use in pellet fires. 5 Background Art Any discussion of the prior art throughout the specification is not an admission that such prior art is widely known or forms part of the common general knowledge in the field. 10 Pellet fires are becoming more popular; they burn compressed pellets of combustible material, normally wood, but corn, grain and other materials are used. The pellets are a uniform size range and composition so their combustion is more predictable than natural wood or coal. 15 Pellet fires automatically feed the fuel into the fire box from a storage hopper. Pellet fires are classified by their method of feeding fuel into the burn pot, top feed or bottom feed. 20 In a bottom feed pellet fire a horizontal auger that normally lies in the base of the burn pot, for at least part of its length, feeds the pellets from the hopper through the burn pot and discharges the ash out the other end. It can be difficult to prevent the fire burning back into the hopper full of fuel if a power failure occurs. The auger is exposed to the full heat of the fire and the abrasive and/or corrosive ash and 25 combustion products. However, aesthetically, many prefer the look of a bottom fed pellet fire as they tend to have a wider exposed flame front. In a top feed pellet fire an inclined auger lifts the pellets from the base of the hopper and discharges them above the burn pot. The pellets then gravity feed into the burn 30 pot, often falling onto an inclined plate first. This feed is from a single tube or chute which forms a single pile of pellets in the burn pot, which some find creates a less aesthetically appealing flame than the bottom feed. The gravity feed section minimises the chance of any burn back into the hopper.

I

It would be advantageous if a fuel feed system for a pellet fire could be devised that at least partly ameliorates one or more of the limitations of existing systems, or provides the consumer with a useful choice. 5 Disclosure of Invention The present invention provides a fuel feed system for a pellet fire which includes conveying means within a casing, said casing including a plurality of inlet means distributed lengthwise along the casing and a plurality of outlet means distributed 10 lengthwise along the casing, such that each inlet means is horizontally offset from the adjacent outlet means and wherein said conveying means is configured to move compressed fuel pellets from an inlet means to an adjacent outlet means; such that in use said fuel feed system is configured to form a plurality of overlapping piles of compressed fuel pellets in a burn pot of the pellet fire. 15 Preferably the longitudinal axis of the casing and the burn pot are approximately parallel. Preferably said inlet means and/or outlet means are apertures in the casing. In a 20 highly preferred form the conveying means is one or more concentrically aligned augers. In a most preferred form the conveying means is a single auger. Preferably the casing is not a single piece of material. In one preferred form the casing is formed by parts of the pellet fire or fuel feed system alone or in combination 25 with additional separate components. In a preferred form the fuel feed system includes a plurality of delivery ducts and/or channels such that each outlet means forms one end of an associated delivery duct or channel, such that at an opposite end of each said delivery duct or channel there is a 30 delivery outlet that is configured to deliver the compressed fuel pellets, directly or indirectly, into the burn pot. Preferably the fuel feed system includes a distribution section which lies between the delivery outlets and the burn pot. In a highly preferred form the distribution section is an angled plate that vertically and/or horizontally separates the delivery outlets and the burn pot. 35 2 WO 20111098932 PCT/IB2011/050405 Preferably where the fuel feed system does not include delivery ducts and/or channels it includes a primary distribution section which lies between the outlet means and the burn pot. In a highly preferred form the primary distribution section is an angled plate that vertically and/or horizontally separates the outlet means and the burn pot. 5 The invention also includes a pellet fire incorporating the fuel feed system. Preferably the pellet fire includes a hopper configured to store compressed fuel pellets such that an outlet of the hopper is coterminous with the fuel feed system. In a highly 10 preferred form the casing lies essentially horizontally across the outlet of the hopper. In a further preferred form the fuel feed system includes a plurality of casings, either separated or coterminous, each with at least one conveying means. 15 Brief Description of Drawings By way of example only, a preferred embodiment of the present invention is described in detail below with reference to the accompanying drawings, in which: Figure 1 is a cutaway pictorial view of a pellet fire showing the fuel feed system; Figure 2 is a pictorial view of a hopper with a fuel feed system and fire box 20 removed from the pellet fire; Figure 3 is a plan view of the hopper with feed system and fire box removed from the pellet fire, with no fuel in the hopper or burn pot; Figure 4 is a cross sectional plan view through the hopper and fuel feed system in the direction of arrows A-A., with no fuel in the burn pot; 25 Figure 5 is a is a plan view of the hopper with feed system and fire box removed from the pellet fire, with fuel pellets in the hopper and interlinking piles of pellets in the burn pot Best Mode for Carrying Out the Invention 30 Referring to Figure 1, a cutaway view of a pellet fire (1) including a first sub-assembly (2) is shown. Said first sub assembly (2) includes a hopper (3), fuel feed system (4) and burn pot (5), such that the hopper (3) is a storage container for compressed fuel pellets of a known type. The hopper (3) is connected to the fuel feed system (4), 35 which in turn is connected to the burn pot (5). 3 WO 20111098932 PCT/IB2011/050405 The burn pot (5) is of a known type that includes a channel (6) with a perforated base (7) which, when the pellet fire (1) is in use, acts as a grate. Other surfaces of the channel (6) or burn pot (5) may also be perforated but this is optional and not shown in the drawings. 5 Referring to Figures 2 to 5 the first sub-assembly (2) is shown removed from the pellet fire (1) for clarity. Figures 2 to 4 show the first sub-assembly (2) without compressed fuel pellets. Referring to figures 2 to 4, where figure 4 is a cross sectional view in the direction of 10 arrows A-A shown in figure 2, the fuel feed system (4) including a second sub assembly (10) is shown. The second sub-assembly (10) includes a conveying means (11), a plurality of inlet means (12) and a plurality of outlet means (13). Each inlet means (12) is separated from the adjacent inlet means (12) by first shield means (14), and each outlet means (13) is separated from the adjacent outlet means (13) by 15 second shield means (15). The conveying means (11) is an auger of known type which lies essentially horizontally (though in some embodiments may be angled) across the base of the hopper (3). The first and second shield means (14,15) form a casing (16) in which the 20 conveying means (11) is located, the inlet and outlet means (12,13) are apertures in this casing (16). Each inlet means (12) is horizontally offset from the nearest outlet means (13) along the length of the casing (16). The first sub-assembly (2) further includes a plurality of delivery means (20) and 25 delivery outlets (21), and a distribution section (22). Each delivery means (20) is a duct which has an outlet means (13) as one end and a delivery outlet (21) as the opposite end. Each delivery means (20) is angled such that the delivery outlet (21) is vertically separated from the associated outlet means (13). The term 'duct' is intended to include hollow prisms with any cross sectional shape, even if the cross sectional 30 shape changes from one end to the other. Each delivery outlet (21) lies above the distribution section (22) which is connected to the burn pot (5). The distribution section (22) is an angled plate extending the length of the channel (6). 35 4 WO 20111098932 PCT/IB2011/050405 Referring to figure 5, the first sub-assembly (2) containing compressed fuel pellets is shown. The fuel feed system (4), in use, creates a plurality of overlapping pellet piles (30), such that in use these overlapping piles form a wide flame front in the burn pot (5). 5 By way of example only the flow of compressed fuel pellets through the first sub assembly with the pellet fire (1) in use will be described. The compressed fuel pellets in the hopper (3) fall, or are pulled through, an inlet 10 means (12). The conveying means (11) then moves these compressed fuel pellets to a horizontally offset adjacent outlet means (13). The compressed fuel pellets then move through the delivery means (20) associated with that outlet means (13) and out of the associated delivery outlet (21). The compressed fuel pellets then fall onto the distribution section (22) and are gravity fed into the channel (6). Each delivery outlet 15 (21) directs compressed fuel pellets onto a separated, but overlapping pellet pile (30) for combustion. As each inlet means (12) is horizontally offset from each adjacent outlet means (13), the mass/volume of compressed fuel pellets through the fuel feed system (4) can be 20 controlled. In other words the compressed fuel pellets cannot fall directly from an inlet means (12) into an outlet means (13), they must be physically moved from one to the other by the conveying means (11). This horizontal separation of adjacent inlet and outlet means (12,13) prevents the compressed fuel pellets from directly feeding from the hopper (3) to the burn pot (5). If the conveying means (11) is stopped then the 25 compressed fuel pellet flow is essentially stopped at the same time. In a further embodiment the fuel feed system (4) is not directly connected to the burn pot (5). In this embodiment the fuel pellets fall from the fuel feed system (4) into the burn pot (5). 30 In a further embodiment (not shown) the distribution section (22) is not present, so that in use the compressed fuel pellets fall directly from each delivery outlet (21) into the burn pot (5). 35 In a further embodiment the second sub-assembly (10) is not at the base of the hopper (3). 5 WO 20111098932 PCT/IB2011/050405 In a further embodiment the conveying means (11) is a plurality of augers each able to be separately driven. 5 In a further embodiment there are two or more augers which may or may not be concentrically aligned. For example (not shown) they may be parallel with horizontal or vertical separation. In one embodiment (not shown) there are one or more additional casings, each 10 separate from or coterminous with the casing (16). Each of these additional casings is similar to the casing (16) in that they include additional inlet and/or outlet means that are horizontally separated, and house one or more additional conveying means. For example there may be two parallel augers within a single casing, two additional conveying means in two separated casings each configured to, either separately or in 15 combination, create a plurality of overlapping pellet piles (30). In a further embodiment (not shown) the conveying means (11) is not located in the casing (16) and the casing (16) is hollow. 20 6

Claims

1. A fuel feed system for a pellet fire which includes conveying means within a casing, said casing including a plurality of inlet means distributed lengthwise along the 5 casing and a plurality of outlet means distributed lengthwise along the casing, such that each inlet means is horizontally offset from an adjacent outlet means and wherein said conveying means is configured to move compressed fuel pellets from an inlet means to an adjacent outlet means; such that in use said fuel feed system is configured to form a plurality of overlapping piles of compressed fuel pellets in a burn 10 pot of the pellet fire.

2. The fuel feed system as claimed in claim 1 wherein the longitudinal axis of the casing and the burn pot are approximately parallel. 15

3. The fuel feed system as claimed in claim 1 or claim 2 wherein the casing and the burn pot are vertically separated.

4. The fuel feed system as claimed in any of the preceding claims wherein the said inlet means and/or outlet means are apertures in the casing. 20

5. The fuel feed system as claimed in any one of the preceding claims wherein the conveying means is one or more concentrically aligned augers.

6. The fuel feed system as claimed in any one of the preceding claims wherein 25 the conveying means is a single auger.

7. The fuel feed system as claimed in any one of the preceding claims wherein the fuel feed system includes a plurality of delivery ducts and/or channels, wherein each outlet means forms one end of an associated delivery duct or channel, such that 30 at an opposite end of each said delivery duct or channel there is a delivery outlet that is configured to deliver the compressed fuel pellets ,directly or indirectly, into the burn pot.

8. The fuel feed system as claimed in claim 7 wherein the fuel feed system 35 includes a distribution section which lies between the delivery outlets and the burn pot. 7

9. The fuel feed system as claimed in claim 8 wherein the distribution section is an angled plate that vertically and horizontally separates the delivery outlets and the burn pot. 5

10. The fuel feed system as claimed in any one of claims 1 to 6 wherein the fuel feed system includes a primary distribution section which lies between the outlet means and the burn pot. 10

11. The fuel feed system as claimed in claim 10 wherein the primary distribution section is an angled plate that vertically and horizontally separates the outlet means and the burn pot.

12. The fuel feed system as claimed in any one of the preceding claims wherein 15 the casing is not a single piece of material.

13. The fuel feed system as claimed in claim 12 wherein the casing is formed by parts of the pellet fire or fuel feed system alone or in combination with additional separate components. 20

14. The fuel feed system as claimed in any one of the preceding claims which includes at least one additional casing, either separated from or coterminous with the casing, wherein the or each additional casing includes one or more additional conveying means. 25

15. A pellet fire including the fuel feed system as claimed in any one of the preceding claims.

16. The pellet fire as claimed in claim 15 wherein it includes a hopper configured 30 to store compressed fuel pellets such that an outlet of the hopper is coterminous with the fuel feed system.

17. The pellet fire as claimed in claim 16 wherein the casing lies essentially horizontally across the outlet of the hopper. 8

18. A fuel feed system for a pellet fire which includes conveying means within a casing substantially in accordance with the embodiment described in the detailed description of the invention with reference to the accompanying drawings. 5

19. A pellet fire including a fuel feed system substantially in accordance with the embodiment described in the detailed description of the invention with reference to the accompanying drawings. 9