Combustion Apparatus

Abstract

Combustion apparatus for use with a solid fuel has a firebox constructed at least in part of a fired refractory carbide material. The fired refractory carbide material has a catalytic effect on the combustion process providing a cleaner and more efficient combustion. The fired refractory material also absorbs heat from the combustion process directly or indirectly by heat exchange with combustion products and dissipates the absorbed heat over an extended period of time providing space heating after the combustion process is completed.

Claims

1. Combustion apparatus for a solid fuel comprising a stove having a body wholly consisting of a fired refractory carbide material, the body providing an outer surface of the stove and a firebox defining a combustion chamber within the body for burning solid fuel.

2. Combustion apparatus according to claim 1 in which the fired refractory carbide material includes silicon carbide.

3. Combustion apparatus according to claim 2 in which the fired refractory carbide material contains at least 40% by weight silicon carbide.

4. Combustion apparatus according to claim 3 in which the fired refractory carbide material contains at least 50% by weight silicon carbide.

5. Combustion apparatus according to claim 4 in which the fired refractory carbide material contains at least 60% by weight silicon carbide.

6. Combustion apparatus according to claim 5 in which the fired refractory material contains up to 90% by weight silicon carbide.

7. Combustion apparatus according to claim 1 in which the outer surface of the stove provides a source of radiated heat.

8. Combustion apparatus according to claim 1 in which the body is provided with a passageway for combustion products to pass through from the combustion chamber to an outlet for discharge and the body is heated by heat exchange with combustion products within the passageway.

9. Combustion apparatus according to claim 8 in which the passageway extends on both sides of the combustion chamber.

10. Combustion apparatus according to claim 1 in which an ash pit is provided below the combustion chamber and has means for controlling admission of air to the combustion chamber.

11. Combustion apparatus according to claim 10 in which the ash pit is provided with an air inlet that provides a minimum air flow to the combustion chamber.

12. Combustion apparatus according to claim 1 in which the firebox has a door for access to the combustion chamber.

13. Combustion apparatus according to claim 1 in which the firebox has an outlet for combustion products at an upper end of the firebox and a baffle arranged to extend below the outlet.

14. Combustion apparatus according to claim 1 in which the firebox is configured to admit air into the combustion chamber for mixing with combustion products within the combustion chamber.

15. Combustion apparatus according to claim 1 in which the body comprises a plurality of sections arranged one on top of the other.

16. Combustion apparatus according to claim 15 in which the body comprises a base section, a lower section, an upper section and a top section and the lower section provides the firebox defining the combustion chamber between the base section and the upper section.

17. Combustion apparatus according to claim 16 wherein the lower section includes a rear wall, opposed side walls and a base wall made of fired refractory carbide material.

18. Combustion apparatus according to claim 1 wherein the body is configured to provide separate inlets for admitting air for primary and secondary combustion processes within the combustion chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] FIG. 1 is a front view of combustion apparatus embodying the invention;

[0057] FIG. 2 is a side view of the combustion apparatus shown in FIG. 1;

[0058] FIG. 3 is a plan view of the combustion apparatus shown in FIG. 1;

[0059] FIG. 4 is a section, to an enlarged scale, on the line A-A of FIG. 1;

[0060] FIG. 5 is section, to an enlarged scale, on the line B-B of FIG. 1;

[0061] FIG. 6 is a section, to an enlarged scale, on the line C-C of FIG. 1;

[0062] FIG. 7 is a perspective view of the body of the combustion apparatus shown in FIGS. 1 to 6;

[0063] FIG. 8 shows a detail of the baffle shown in FIG. 4;

[0064] FIG. 9 is a section on the line D-D of FIG. 8;

[0065] FIG. 10 shows a modification of the combustion apparatus of FIGS. 1 to 9 to include a further baffle;

[0066] FIG. 11 is a front view of the further baffle shown in FIG. 10;

[0067] FIG. 12 is a perspective view showing a modification to the body of FIG. 7;

[0068] FIG. 13 is a front view of the body shown in FIG. 12; and

[0069] FIG. 14 is a side view of the body shown in FIG. 12.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0070] Referring first to FIGS. 1 to 7 of the drawings, there is shown combustion apparatus in accordance with the invention in the form of a stove 1 for use with a solid fuel such as wood, coal etc.

[0071] The stove 1 comprises a free standing body 3 constructed from blocks of a fired refractory material arranged in sections one on top of the other that are designated a base section 5, a lower intermediate section 7, an upper intermediate section 9 and a top section 11. The number of sections may vary according to the design of the stove 1.

[0072] In this embodiment, the base section 5, upper intermediate section 9 and top section 11 each comprise a single block although this is not essential and one or more of these sections may comprise a plurality of blocks. The lower intermediate section 7 comprises a plurality blocks assembled to provide a firebox 13 that defines a combustion chamber 15. The blocks include a rear block 7a, a pair of side blocks 7b, 7c and a base block 7d.

[0073] The rear block 7a forms the back wall of the firebox 13. The side blocks 7b, 7c form the side walls of the firebox 13. The base block 7d forms the bottom wall of the firebox 13 and supports a grate (not shown). The top wall of the firebox 13 is formed by the upper intermediate section 9.

[0074] The firebox 13 is closed by a door 17 mounted at the front of the stove 1. The door 17 can be opened to provide access to the firebox 13 for placing solid fuel on the grate in the firebox 13. The door 17 typically includes a heat resistant glass window 17a that allows the combustion process within the firebox 13 to be viewed without opening the door 17.

[0075] Also mounted at the front of the stove 1 is a door 19 that can be opened and closed to provide access to an ash pit 21 located below the combustion chamber 15.

[0076] Combustion air for the primary combustion process is admitted to the combustion chamber 15 through an opening 23 in the base block 7d of the upper intermediate section 7 in which the grate (not shown) is seated. The opening is rectangular but this is not essential and the opening 23 may have other shapes. The grate supports solid fuel placed in the combustion chamber 15 and allows ash from the combustion process to fall into the ash pit 21.

[0077] The primary air flow to the combustion chamber 15 includes a fixed flow provided by an air inlet port 25 in the rear wall of base section 5 and a variable flow provided by adjusting opening of the door 19. Any other means for providing a variable air flow may be provided.

[0078] The inlet port 25 provides a minimum air flow if the door is 19 is closed. More than one air inlet port 25 may be provided. In a modification (not shown), the air inlet port 25 may be omitted.

[0079] Combustion air for a secondary combustion process is admitted to the combustion chamber 15 through an air inlet duct 27 leading to a slot 29 that opens to the combustion chamber 15 above the door 17.

[0080] The secondary air flow is preheated as it passes through duct 27 and slot 29 and is directed downwards across the inside face of the door 17 by a baffle 30 located at the top of the combustion chamber 15.

[0081] The secondary air flow creates turbulence and re-combustion of the combustion products within the combustion chamber 15.

[0082] Opening of the duct 27 can be controlled to vary the flow of secondary combustion air to the combustion chamber 15 by a manually operable control member (not shown). The air inlet duct 27 may be closed to prevent admission of secondary combustion air. Any other means for providing a variable air flow may be provided.

[0083] The baffle 30 also serves to direct hot combustion products that rise within the combustion chamber 15 to an outlet port 35 at the top of the combustion chamber 15.

[0084] The outlet port 35 leads to a passageway 37 that splits into two flow paths 39, 41 that extend either side of the combustion chamber 15 within the body 3 of the stove 1 before recombining to deliver the combustion products to an outlet 43 at the top of the stove 1. The outlet 43 is connected to a flue (not shown) for discharging the combustion products to atmosphere.

[0085] Each flow path 39, 41 of the passageway 37 is generally U-shaped with a first leg 47 that receives the combustion products from the combustion chamber 15 and a second leg 49 that delivers the combustion products to the outlet 43.

[0086] The first and second legs 47, 49 are arranged vertically within the body 3 of the stove with the first leg 47 towards the front of the stove and the second leg 49 towards the back of the stove 1. In this embodiment, the first and second legs 47, 49 are of rectangular cross-section although this is not essential and other cross-sections may be employed.

[0087] The flow paths 39, 41 preferably extend substantially the full height of the body 3. In this way the heat from the combustion products is transferred to substantially the whole of the body 3 of the stove 1. As a result, the temperature of the combustion products is significantly reduced before the combustion products are discharged to atmosphere.

[0088] Access to the passageway 37 for cleaning is provided by holes 51 in the top section 11 that open to the upper ends of the legs 47, 49 of the flow paths 39, 41 and by holes 53 in the base section 5 that open to the lower ends of the legs 47, 49 of the flow paths 39, 41. The holes 51 are closed by removable plugs 55 and the holes 53 are closed by removable plugs 57.

[0089] Access to the ash pit 21 for a riddling device (not shown) is provided by an opening 59 in the base section 5 above the door 19. The opening 59 is closed by a removable plug 61.

[0090] The sections 5, 7, 9, 11 of the body 3 are made of a fired refractory carbide material which preferably includes silicon carbide in an amount of at least 40% by weight, more preferably at least 50% by weight, still more preferably at least 60% by weight and may include up to 90% by weight silicon carbide.

[0091] The presence of silicon carbide improves the combustion of the solid fuel in the combustion chamber 15 and the transfer and retention of heat from the combustion gases to the body 3 of the stove 1. As a result, heat extraction is improved and the stove 1 can continue to radiate heat over an extended period of time after the solid fuel has been burnt.

[0092] Referring now to FIGS. 8 and 9 of the drawings, the baffle 30 is shown in more detail.

[0093] The baffle 30 comprises two plates 31, 32 configured as shown. The plate 31 extends between two angle bars 63a, 63b and a further angle bar 65 extends along a front edge of the plate 31. The plate 31 is angled downwardly and extends below the outlet port 35 so that the hot combustion products are directed to flow towards the outlet port 35.

[0094] The plate 32 has a first portion 32a that extends horizontally and a second portion 32b that is angled downwardly below the slot 29 so that the secondary air flow is directed across the inside face of the door 17.

[0095] The plates and bars are made of steel or other materials capable of withstanding the operating temperature of the stove.

[0096] Referring now to FIGS. 10 and 11, a modification of the combustion apparatus of FIGS. 1 to 7 is shown.

[0097] In this modification, an air inlet port 67 is provided in the rear block 7a that forms the back wall of the firebox 13 just above the base block 7d at the bottom of the combustion chamber 15.

[0098] A baffle 69 comprising a rectangular plate of heat resistant material such as steel or vermiculite is provided in the firebox 13 rearwardly of the grate.

[0099] The baffle 69 extends from the base block 7d to the top of the rear block 7a and extends between the side blocks 7b, 7c to define an enclosed space 71 within the firebox 13 at the back of the combustion chamber 15.

[0100] The air inlet port 67 opens to the space 71. The baffle 69 is provided with six circular holes 73 of uniform size and shape towards the upper end.

[0101] The number of holes 73 may be varied. The size of the holes 73 may be varied. The shape of the holes 73 may be varied. The holes 73 may be the same or different. The position of the holes 73 may be varied.

[0102] Combustion air for a further secondary combustion process is admitted to the lower end of the space 71 through the inlet port 67 and is pre-heated as it flows to the upper end from where it passes into the combustion chamber 15 through the holes 73.

[0103] The air flow from the holes causes turbulence and re-combustion of the combustion products flowing towards the outlet port 35 at the top of the combustion chamber 15 in a secondary combustion process.

[0104] Referring now to FIGS. 12 to 14, a modification to the body 3 of the combustion apparatus of FIG. 7 is shown.

[0105] In this modification, the access holes 51 for cleaning the passageway 37 are provided in the side of the upper intermediate section 9 and the top section 11 is modified to allow heat exchange with a heat transfer fluid.

[0106] As shown, the top section 11 is provided with a recessed portion 75 on the underside that defines with the upper intermediate section 9 an enclosed space 77 within the body 3 separate from the combustion chamber 15.

[0107] A heat exchange fluid can be circulated through a coil or similar heat transfer device (not shown) located within the space 77 by means of ducting (not shown) connected to the heat transfer device via holes 79 in the top section 11.

[0108] The coil is preferably in thermal contact with the body 3 whereby the fluid is heated by heat transfer from the body 3 through the coil.

[0109] The heat exchange fluid may be air and the warm air generated may be used for space heating in the room containing the stove and/or in another room.

[0110] Alternatively, the heat exchange fluid may be water and the hot water generated may be used for washing or space heating, for example the hot water may be circulated in a hot water system or a central heating system.

[0111] It will be understood that the invention is not limited to the embodiments above-described. For example, other constructions for the body are contemplated including both modular constructions employing separate sections as described and monolithic constructions employing a single section may be employed.

[0112] In the above-described embodiments, air for the primary and secondary combustion processes is drawn from within the space (room) in which the stove is located. In some applications, it may be desirable to draw air from outside. In this case, ducting may be employed to deliver air drawn from outside to the stove. The ducting may supply air to one or more inlets. Means may be provided to adjust the air flow to any inlet.

[0113] Moreover, features of any of the embodiments may be employed separately or in combination with features of any of the other embodiments.