GB2070233A - Improvements relating to sawdust burning stoves - Google Patents

Abstract

A stove comprises an outer casing (1) and an inner container (3). A two-part former is positioned within the container (3) and sawdust (or other particulate fuel) is compressed in the remaining space so that when the former is removed a central passageway (22) remains leading from a lower inlet (4) aligned with an inlet passageway (2) of the casing (1) which incorporates an adjustable draught regulator (17). The sawdust is burned within the passageway (22) and hot gases pass through a central opening and end cap (9), are deflected by a plate (12) in a lid closing off the casing (1) and, after passing through the space (23), leave via the exhaust flue (14). The walls of the casing (1) are heated by the hot gases and this heat is radiated for heating purposes. The casing (1) could also incorporate a water jacket for heating water. <IMAGE>

Description

SPECIFICATION Improvements relating to burners This invention relates to a burner for producing heat and which will use as a fuel sawdust or other compressible particulate combustable material. The object of the invention is to provide a burner which will readily burn a fuel of this type and will give out a large proportion of the heat created as a result of the burning process.

Accordingly this invention provides a burner for sawdust or other compressible particulate fuel, comprising a container having a lower inlet and an open top closed by a removable cap having an outlet opening therein, and a removable former for defining a central passageway from the inlet to the top of the container.

The passageway created when the former is removed acts to allow air for combustion to pass up through the interior of the compacted block of sawdust or the like and the hot gases leaving the top of the passageway can be used for heating purposes. Ideally the burner will include an outer casing provided with a removable lid and surrounding the container, the casing having a lower inlet passageway for alignment with the lower inlet of the container, and an exhaust outlet from the side of the casing. The walls of the outer casing will be heated by the hot gases flowing through the space between the casing and the container on their way to the exhaust outlet and this heat will be radiated to provide warmth for room heating for example. A water heater could also be situated in the space between the container and the casing, for example to provide domestic hot water.

Where the burner is also provided with the outer casing it is preferred that the lid should include deflector plates downwardly directed towards the outlet opening in the cap. It is also desirable to provide raised supports on the base of the casing to carry and locate the container and allow for air circulation under the container. The casing may be designed to receive two containers and will then incorporate a lower inlet passageway for each container. With a dual unit of this type the fuel could be burnt in both containers at once or the second one can be lit when the fuel in the first has been completely burnt.

In the preferred arrangement the former includes a separate portion leading across the container from the inlet to the central passageway. The cap will ideally be in the form of an upwardly extending truncated cone. It is also an advantage to include a removable holder for maintaining the top of the former centrally with respect to the sides of the container. In order to provide control of the rate of burning of the fuel the lower inlet or the inlet passageway can be provided with a draught regulator.

The invention also extends towards a method of burning sawdust or other compressible particulate fuel wherein the fuel is compressed into a container provided with a remo vable former defining a central passageway between a lower inlet into the container and the container top, the former is removed and the fuel is ignited so that air for combustion passes from the lower inlet through the central passageway in the compressed fuel so as to burn the fuel progressively from the inside out to the container wall.

The invention may be performed in various ways and preferred embodiments thereof will now be described with reference to the accompanying drawings, in which: Figure 1 is a vertical section through a preferred form of burner of this invention; Figure 2 is a plan view of the burner with the top lid removed; Figure 3 is an exploded view of parts of the burner; and Figure 4 illustrates a possible modification enabling water to be heated by the burner.

The burner shown in Figs. 1 to 3 comprises an outer casing 1 having a lower inlet passageway 2 and an inner container 3 having a lower inlet 4 which is aligned with the passageway 2. The container 3 is positioned on support struts 5 which carry upwardly projecting aligning pins 6. The container 3 is provided with carrying handles 8 and is closed by a cap 9 having a central opening 10 which acts as an outlet for hot gases within the container 3 when the burner is in operation.

The casing 1 is closed by a lid 11 provided with a downwardly directed conical deflector 1 2. Asbestos string 1 3 situated in a groove of the lid 11 seals the connection between the lid and the casing 1. The casing 1 is provided with an exhaust outlet 1 4 incorporating a damper 1 5 operable by a lever 1 6. A removable draught regulator 1 7 is positioned within the inlet passageway 2 and incorporates a perspex window 1 8 carried by a screwthreaded spigot 1 9. When the plate 1 8 is rotated a gap will be formed between this plate and the walls of the regulator 1 7 and the extent of gap will determine the draught through the apparatus.

When the burner is to be used for burning sawdust a two-part former is first introduced into the container 3. The former comprises a slightly tapered rod or tube part 20 (of metal or wood for example) and a further piece 21 which passes through the inlet 4 and aligns with the lower end of the vertical former part 20. A removable holder 24 clips onto the side of the container 3 and has a ring which locates over the top of the part 20 to hold it centrally. The other end of the part 20 is centralised by a locating pin 7 on the container base. The container is then filled with sawdust which is pressed down very firmly to create a compacted block of sawdust within the container. The former parts 20 and 21 can then be removed (vertically and horizontally) to leave a central passageway 22 through the body of the sawdust.The container is then lowered into position in the casing 1 so that the inlet 4 and the inlet passageway 2 are aligned and the cap 9 and lid 11 are placed in their respective positions and the draught regulator is also fitted within the inlet 4 and the inlet passageway 2. The sawdust can be ignited at the base by any suitable means (either before or after positioning the draught regulator) and the sawdust will then commence burning within the passageway 22 out towards the outer walls of the container 3.Air passes through the draught regulator 1 7 and out through the passageway 22 and the hot exhaust gases pass out through the restricted opening 10 in the cap 9 and are then deflected downwardly by the deflector 1 2 through the space 23 between the walls of the casing 1 and the container 3 until eventually they pass out through the exhaust flue 14. The hot gases within the space 23 cause the walls of the casing 1 to heat up and radiate heat.

The convection currents of the hot gases within the space 23 result in a substantial proportion of the heat being given up for radiaton by the casing 1 so that little heat is lost through the exhaust flue 14. Furthermore the rate of burning of the fuel is relatively slow so that the burner operates very economically. For example apparatus constructed in this manner has been operated to burn ten pounds of sawdust in four and a half hours with a substantial emission of heat.

As shown in Fig. 4, the casing 1 could be modified to incorporate a water heating jacket 25 provided with a number of openings 26 through which the hot gases can pass and heat water passing through the jacket via the inlet and outlet pipes 27, 28. Fig. 5 illustrates a modified design of the casing 1 adapted to receive a pair of containers 3 and therefore two inlet passageways 2 are provided into the casing. There is a common space 23 within the casing 1 for the two containers 3, which leads to the exhaust flue 14. Fuel can be burned in the two containers 3 at the same time to create an enhanced heat output or alternatively the fuel in each container can be ignited in sequence so that heating need not cease when the fuel in one container has burned away.

Other modifications may readily be made to the design of the heater. For example the window 1 8 could be formed from glass or even a non-transparent material (such as metal) if viewing of the interior is not essential.

The design of the complete heater provides that a substantial amount of the heat energy produced by burning the compressed sawdust or other fuel is radiated from the heater. For example, the cap 9 mounted on the top of the container 3 acts as a heat harnesser to control the emission of heat 'from the burning fuel.

Also the low position of the exhaust outlet 14 allows the hot gases to circulate within the space 23 for some time before the somewhat cooler gases are exhausted so that less heat is lost to the flue than with the type of heater having a top exhaust outlet.

Claims (11)

1. A burner for sawdust or other compressible particulate fuel, comprising a container having a lower inlet and an open top closed by a removable cap having an outlet opening therein, and a removable former for defining a central passageway from the inlet to the top of the container.

2. A burner according to claim 1, wherein the former includes a separate portion leading across the container from the inlet to the central passageway.

3. A burner according to claim 1 or claim 2, wherein the cap is in the form of an upwardly extending truncated cone.

4. A burner according to any of claims 1 to 3, including a removable holder for maintaining the top of the former centrally with respect to the sides of the container.

5. A burner according to any one of claims 1 to 4, including an outer casing provided with a removable lid and surrounding the container, the casing having a lower inlet passageway for alignment with the lower inlet of the container, and an exhaust outlet from the side of the casing.

6. A burner according to claim 5, wherein the lid includes deflector plates downwardly directed towards the outlet opening in the cap.

7. A burner according to claim 5 or claim 6, wherein raised supports are provided in the base of the casing to carry and locate the container.

8. A burner according to any one of claims 5 to 7, including a water heater situated in the space between the container and the casing.

9. A burner according to any one of claims 5 to 8, wherein the casing is designed to receive two containers and incorporates a lower inlet passageway for each container.

1 0. A burner according to any one of claims 1 to 9, wherein the lower inlet or the inlet passageway is provided with a draught regulator.

11. A burner substantially as herein described with reference to the accompanying drawings.

1 2. A method of burning sawdust or other compressible particulate fuel wherein the fuel is compressed into a container provided with a removable former defining a central passageway between a lower inlet into the con tainer and the container top, the former is removed and the fuel is ignited so that air for combustion passes from the lower inlet through the central passageway in the compressed fuel so as to burn the fuel progressively from the inside out to the container wall.