Fuel Burner

Description

The present invention relates to a burner for combustible liquid fuel.

Liquid fuels, such as aliphatic-type alcohol and hydrocarbons subsisting of vegetable origin fatty acids, may be cheaply and easily produced from agricultural crops such as sugarcane or spoilt vegetation. It would therefore be advantageous for developing countries, such as Madagascar, to be able to use the derivatives of such products as fuel. Although methods of utilising such fuels for energy production are presently undertaken in countries such as Brazil, they are used on a large industrial scale or in complex machinery such as car engines. Therefore, a need exists for a means of using such fuel on a small scale which can be simply and cheaply produced and used for purposes such as heating, cooking or lighting in people's homes.

Small-scale devices to burn combustible liquid fuel, such as alcohol-based fuels, are generally well known and are in widespread use. However, such devices are very limited in use and are generally only used as camping stoves or the like as they do not produce a large amount of heat or light. Such conventional burners generally comprise a container to hold the liquid fuel, wherein the upper surface of the fuel is exposed to the air and the fuel ignited to produce a flame. However, since the fuel is allowed to burn unrestrictedly, and due to the highly volatile nature of these kinds of fuels due to their low flash-point, such devices are highly inefficient and are dangerous to use especially on a larger scale as there is no means to control the supply of fuel to the flame or separate the flame from the fuel's storage container.

An alternative type of conventional liquid fuel burner which seeks to overcome some of the above problems comprises a wick. The wick is generally formed from a fibrous material, one end of which is disposed in a storage container for the fuel and the other end exposed to the air. The fiberous material soaks up the liquid fuel such that fuel is absorbed up to the distal end of the wick and then the fuel soaked wick may be lit. However, such fuel burners can only be used on a very limited scale due to the restrictions of using a conventional wick and so are of limited use for

heating, cooking or the like. A further disadvantage of such burners is that the wick is slowly burned down and must be replaced on a regular basis which may be expensive. Additionally, with this type of fuel some burners suffer from "flashback" wherein the flame of the burner is allowed to return to the fuel storage container with dangerous results.

The present invention seeks to provide a liquid fuel burner that overcomes or substantially alleviates the problems with burners for liquid fuel referred to above.

According to the present invention, there is provided a burner for liquid fuel comprising a housing having an open end, a non-flammable, porous substance disposed in the housing, said substance being communicable with a supply of liquid fuel remote from the open end of the housing so that fuel is drawn through said substance when supplied thereto to an exposed surface at the open end for combustion thereon.

Preferably, the substance is a composite material comprising a porous primary material bound by a secondary fuel-impervious binding material. The substance may be non-degradable in the sense that it may support combustion of the fuel without any effect on the substance itself.

In one embodiment, the secondary fuel-impervious binding material is cement.

The porous substance may comprise a solid material with pores formed therethrough.

Advantageously, the pores are configured such that flashback through the substance is prevented.

The non-flammable porous substance may comprise alumino-silicate or metal oxides.

Preferably, the substance is configured so that fuel is wicked towards the exposed surface due to capillary action.

The burner for liquid fuel may comprise means for supplying liquid fuel to the substance from a fuel supply source. Preferably, said means comprise a remote fuel tank and a pipe extending between the tank and the housing and attached to the housing remote from its open end to supply fuel from the tank to the substance in the housing.

In one embodiment, the remote fuel tank is disposed above the housing such that fuel is gravity fed through the pipe to the substance in the housing.

Advantageously, the housing is disposed in a fuel tank configured such that the open end of the housing is situated above the level of the fuel in the tank, the housing having an opening in a lower end remote from its upper end for the flow of fuel into the housing from the fuel tank.

In a preferred embodiment, the fuel tank has a base and the housing is spaced from the base by posts extending therebetween.

In an alternative embodiment, the fuel tank has a base and the substance extends beyond the opening in the lower end of the housing and supports the housing on the base.

Preferably, the fuel tank is closed.

The burner for liquid fuel may comprise a channel formed about the housing proximate to its open end and exposed surface of the substance such that excess fuel drawn to the exposed surface flows out of the housing via the open end and into the channel. Excess fuel drawn to the combustion surface is drained off into the channel. The channel may also contain a similar substance to that contained in the housing so that a reverse capillary action effect is achieved and the fuel is drawn away from the combustion surface through the substance disposed in the

channel. This prevents flashback and prevents ignition of the excess fuel in the channel.

Preferably, the channel contains a non-flammable, porous substance such that liquid fuel flowing into the channel is drawn into said substance away from the exposed surface.

Advantageously, the non-flammable, porous substance disposed in the channel is a composite material comprising a porous primary material bound by an secondary fuel-impervious binding material such that the liquid fuel is wicked up by the porous material to pass through the non-flammable, porous component.

Preferably, the burner for liquid fuel, comprises a plate disposed over the open end of the housing and exposed surface of the non-flammable, porous substance, said plate having apertures therein to allow fuel at the exposed surface to burn.

In one embodiment, the liquid fuel is alcohol-based.

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a cross-sectional view of a liquid fuel burner in accordance with an embodiment of the present invention;

Figure 2 is a perspective view of the liquid fuel burner shown in Figure 1; Figure 3 is a top-plan view of the liquid fuel burner shown in Figures 1 and 2;

Figure 4 is a cross-sectional view of a liquid fuel burner shown in Figures 1 to 3;

Figure 5 is a cross-sectional view of a liquid fuel burner in accordance with a second embodiment of the present invention;

Figure 6 is a cross-sectional view of a liquid fuel burner in accordance with a third embodiment of the present invention;

Figure 7 is a cross sectional view of a liquid fuel burner in accordance with a fourth embodiment of the present invention; and

Figure 8 is a top plan view of the liquid fuel burner shown in Figure 7.

Referring now to the drawings, there is shown in Figures 1 and 2 a liquid fuel burner 1 according to an embodiment of the present invention which allows and sustains combustion of a liquid fuel, such as an aliphatic-type alcohol with a predetermined viscosity. The burner 1 comprises a cylindrical body 2 with a fuel support portion 3 disposed therein and a fuel storage container 4. The cylindrical body 2 is a tube with upper and lower ends 5, 6 and a tubular opening 7 extending therethrough to communicate between each end 5, 6. The cylindrical body 2 is formed from a material which is impervious to the liquid fuel to be utilised.

The fuel support portion 3 is cylindrical and is disposed in the tubular opening 7 of the cylindrical body 2, wherein the inner diameter of the cylindrical body 2 corresponds to the outer diameter of the fuel support portion 3. The fuel support portion 3 has upper and lower surfaces 8, 9 and the fuel support portion 3 extends through the tubular opening 7 such that the upper and lower surfaces 8, 9 correspond to the faces 5a, 6a of the upper and lower ends 5, 6 of the cylindrical body 2. Alternatively, the upper and lower surfaces 8, 9 may extend above or below the upper and lower faces 5, 6 as will be explained hereinafter.

In this embodiment the fuel support portion 3 is slotted into the cylindrical body 2 and located by means of a mounting ridge (not shown) which protrudes into the lower end of the tubular opening 7 and extends therearound. However, it will be appreciated that the invention is not limited thereto and that alternative mounting means may be used, for example, the fuel support portion 3 may be moulded into place within the tubular opening 7 of the cylindrical body 2.

Further, in the embodiment shown the cylindrical tube 2 and corresponding fuel support portion 3 are cylindrically shaped, however, they may be formed from any shape with a hollow section formed therethrough, for example, a rectangular prism.

The fuel support portion 3 of the present embodiment is formed from a suitable material, or composite of materials, as will be discussed hereinafter, such that the fuel support portion 3 is porous to allow a liquid fuel to be drawn therethrough.

The material may be produced from a compound such Alumino-silicate or metal oxides extracted from their sources such as sand and is formed to have a specific hydraulic conductivity such that the porous substrate has a capillary action to draw or allow liquid fuel therethrough. In one alternative the fuel support portion 3 is formed from a pulverised porous material which is bound together by a binder material, such as Portland cement. Alternatively, if there is no binder material then the capillary action is produced by the space provided in between the pulverised material.

The upper surface 8 of the fuel support portion 3 forms a combustion area and is a planer surface in Figure 1, although it is not limited thereto and may form a number of alternative shapes dependent on the intended use of the burner 1. For example, if the burner 1 is used for lighting then the combustion area may extend from the body in a cone shape to increase the available surface area of the combustion area.

The fuel storage container 4 has a base 12 and sidewalls 13 which extend around the base 12 and perpendicularly therefrom. The base 12 and sidewalls 13 provide a container to hold fuel therein with an opening 14 formed at the upper end 4a of the fuel storage container 4. The cylindrical body 2 and fuel support portion 3 form an assembly 11 which is disposed in the fuel storage container 4, and an upper end 15 of the assembly 11 extends through the opening 14 thereof. The assembly 11 is supported in the fuel storage container 4 by means of base support posts 16 and side support posts 17. The base support posts 16 support the assembly 11 such that a gap is formed between the lower surface 9 of the assembly 11 and the base 12 of the fuel storage container 4 and so the lower surface 9 of the fuel support portion 3 is exposed to fuel disposed in the fuel storage container 4, for reasons that will become apparent hereinafter. The support posts 16, 17 are mounted to the fuel storage container 4 and the assembly 11 by known means.

Alternatively, the cylindrical body 2 may extend from the lower surface 9 of the fuel support portion 3 so that the assembly 11 is supported on the base 12 of the fuel storage container 4 by the lower end 6 of the cylindrical body 2 and apertures (not

shown) are formed through the lower end 6 of the cylindrical body 2 such that fuel can flow therethrough.

Referring to Figure 4, in a further alternative the assembly 11 may be supported by the lower surface 9 of the fuel support portion 3 being disposed directly on the base 12 of the fuel storage container 4, wherein the fuel support portion 3 extends from the lower end 6 of the cylindrical body 2 so that a lower area 10a of the fuel support portion outer surface 10 is exposed to fuel in the fuel storage container 4.

A lid 18 with an aperture 19 formed therethrough corresponding to the outer diameter of the cylindrical body 2 is mounted over the opening 14 of the fuel storage container 4, wherein the cylindrical body 2 extends through said aperture 19. The lid 18 is removably sealed to an upper end 20 of the sidewalls 13 and to an outer surface 21 of the cylindrical body 2 by rubber gaskets 25.

Referring now to Figure 3, a grill 22 covers the upper surface 8 of the fuel support portion 3. The grill 22 is held in position by a rim 23, which extends around the edge of the grill 22. Apertures 24 are formed through the grill 22, and are shown to be a pair of opposing semi-circular apertures 24 in Figures 2 and 3, although they may be formed in any desired shape as will become apparent later.

The operation of the burner 1 according to the present embodiment will now be described. The lid 18 is removed to expose the opening 14 in the fuel storage container 4, and liquid fuel, as described above, is inserted therein. The lid is subsequently replaced so that the rubber gaskets 25 seal the fuel storage container 4 to prevent detriment entering the fuel storage container 4 and contaminating the fuel. The fuel is inserted into the fuel storage container 4 to a level above the lower surface 9 of the fuel support portion 3 so that the fuel support portion 3 is exposed to the fuel. In the arrangement wherein the fuel support portion 3 extends from the lower end 6 of the cylindrical body 2 the fuel does not have to be at a minimum level as the fuel support portion 3 extends to the base of the fuel storage container 4.

As the fuel support portion 3 is porous or is formed from a solid pulverised material, as discussed above, with a specific hydraulic conductivity, the fuel is drawn therethrough due to a capillary action until the fuel support portion 3 is saturated with fuel. The cylindrical body 2 of the burner 1 holds the fuel support portion 3 in place and prevents fuel from been expelled through the side surfaces 10 of the fuel support portion 3 as it becomes saturated with fuel. As the fuel support portion 3 becomes saturated, fuel is forced to the upper surface 9 of the fuel support portion 3 and is expelled therefrom.

The upper surface 8 of the fuel support portion 3 forms a combustion area 26, and so the liquid fuel, which has been drawn up through the fuel support portion 3 to saturate it, is expelled therefrom and ignited to produce a flame for heating and/or lighting purposes. As the fuel support portion 3 only has a limited hydraulic conductivity, then the rate at which fuel is supplied to the combustion area 26 is limited and so the rate of consumption of the fuel is regulated. The viscosity of the fuel also determines the flow rate of the fuel through the fuel support member 3.

Additionally, due to the limited gaps in the substrate and the porous material then flashback is prevented through the fuel support portion 3. This occurs when the flame is allowed to travel along the feed path, in this case, through the fuel support member 3, to the fuel storage area, the fuel storage container 4. However, in the present arrangement, with the fuel support portion 3, flashback is prevented as the interstices between the material in the fuel support portion 3 are insufficiently sized to allow a flame to burn therethrough. Further, as the fuel support portion 3 is formed from non-flammable material then it is not burnt down due to the action of the flame and so does not need to be replaced.

The apertures 24 of the grill 22 allow combustion of the fuel to take place therethrough, however, combustion of the fuel proximate to the areas covered by the grill 22 is prevented. This allows a specific pattern of flame to be produced dependent on the intended use of the burner 1.

A second embodiment of the present invention will now be described with reference to Figure 5. The arrangement of the burner 1 in this embodiment of the invention is generally the same as the embodiment described above, however, in this embodiment the fuel storage container 4 forms a secondary fuel storage container 30 which communicates with a primary fuel storage container 31 as will be described below.

The primary fuel storage container 31 is a hollow cylindrical tank for containing liquid fuel. A flow pipe 32 is mounted by known means to a base 33 of the primary fuel storage tank 31 at one end and communicates with the inside of the primary fuel storage container 31 through an aperture 34 in the base 33 thereof. The flow pipe 32 is mounted at its distal end to the secondary fuel storage container 30 by known means and communicates through an aperture 35 formed in the secondary fuel storage container 30.

An adjustable valve 36 is mounted in the flow pipe 32 to control the flow of fuel therethrough. The primary fuel storage container 31 is mounted in a position higher than the secondary fuel storage container 31 for reasons which will become apparent hereinafter. In such an embodiment, the Ud 18 of the secondary fuel container 30 is fixedly mounted to the upper end 20 of the sidewalls 13 of the secondary fuel storage container 31 by known means and sealed thereagainst, and the lid aperture 18 is sealed against the cylindrical body outer surface 21 by means of the rubber gaskets 25.

Operation of the burner 1 according to the second embodiment will now be described. The burner 1 is composed as described above and fuel is inserted into the primary fuel storage container 31. As the primary fuel container 31 is disposed to be higher than the secondary fuel container 30, then the head of the fuel therein is higher and the fuel is gravity fed so that it subsequently flows through the flow pipe 32 to the secondary fuel storage container 31. The adjustable valve 36, mounted in the flow pipe 32, is calibrated so that it controls the flow of the fuel therethrough.

As the lid 18 is sealed against the upper end 20 of the sidewalls 13 and the outer surface 21 of the cylindrical body 2, then the flow of the fuel into the secondary fuel storage container 30 from the primary fuel storage container 31, which is dependent on the setting of the adjustable valve 36, causes an increased pressure therein. Dependent on the configuration of the fuel support member, as discussed above, the increase in pressure in the secondary fuel storage container 30 produces an increased flow rate through the fuel support member 3.

The fuel expelled from the upper surface 8 of the fuel support member 3 is then ignited as discussed in the previous embodiment. However, in this embodiment the valve 37 can be adjusted, for example shut off, to prevent or control the flow of fuel therethrough and so the rate of fuel supplied to the upper surface 8 of the fuel support portion 3 may be partially controlled.

A third embodiment of the invention is shown in Figure 6. The cylindrical body 2 and fuel support portion 3 assembly 11 together with the primary and secondary fuel storage containers 31, 30 of this invention are generally the same as those of the second embodiment described above, however, in this embodiment the fuel flow through the fuel support portion may be less restricted.

In this embodiment a fuel overflow channel 41 is formed circumferentially around the upper end 15 of the assembly 11. The fuel overflow channel 41 comprises a channel section with a channel base 42 and inner and outer channel walls 43, 44. The channel 41 extends circumferentially around the upper end 15 of the assembly 11 such that the inner wall 43 contacts the outer surface 21 of the cylindrical body 2 and is sealed thereagainst to prevent fuel flowing in between. The inner channel wall 43 is formed to extend no further than the cylindrical body upper end 5 such that any excess fuel expelled from the fuel support portion 3 flows over the upper end 5 of the cylindrical body 2 and the inner channel wall 43 into the channel.

Disposed in the channel 41 is a channel fuel-saturating portion 45. The channel fuel-saturating portion 45 is composed of the same material to the fuel support portion 3, described in the previous embodiments, such that liquid fuel is allowed to

draw therethrough. The channel fuel-saturating portion 45 is mounted in the channel 41 such that it extends therearound, and is mounted proximate to the channel opening 46 between the inner and outer walls 43, 44. However, the base 47 of the channel fuel-saturating portion 45 is spaced from the channel base 41 such that there is a channel space 48 disposed therebetween.

Apertures 50 are formed in the channel base 41 and a drainage pipe 51 is mounted to each channel base aperture 50, extending to a drainage container 52. Alternatively, a valve (not shown) may connect between the channel base 42 and through the lid 18 of the secondary fuel storage container 30 thereto. The valve (not shown) is a one-way valve such that fuel can only flow from the channel base 42 to the secondary fuel storage container 30. In a further alternative, the excess fuel in the fuel overflow channel 41 may be pumped through a return pipe (not shown) to the primary fuel storage container 31 by means of a pump (not shown).

Operation of the above embodiment will now be described. The burner 1 operates in generally the same way as the previous embodiment, however, in this embodiment there is a means of collecting any excess fuel which is not burnt by the flame. If the up flow of fuel through the fuel support portion 3 exceeds the rate of consumption of the fuel then the excess fuel flows over the upper end 5 of the cylindrical body 2 and the channel inner wall 43 into the channel 41. The fuel is then drawn into the channel fuel-saturating portion 45 due to the nature of the channel fuel-saturating portion 45 as discussed above until it becomes saturated with fuel. The channel fuel-saturating portion 45 prevents the occurrence of flashback therethrough as in it cannot ignite due to the lack of air supply.

The fuel is then expelled from the channel fuel-saturating portion 45 into the channel space 48 below before flowing through the drainage pipes 51 to the corresponding drainage containers 52. It will be understood that the number of drainage containers 52 and pipes 51 may vary, however more than one aperture 50 and corresponding pipe 51 is preferable in the case that the burner 1 is in an inclined position.

The excess fuel is filtered through the channel fuel-saturating portion 45 such that it can then be returned to the primary or secondary fuel storage containers 31, 30 without being contaminated by detriment. It is noted that the outer channel wall 44 may extend further than the inner channel wall 43 to prevent further overspill of the fuel.

A fourth embodiment of the present invention will now be described with reference to Figure 7. The arrangement of the burner 1 of this embodiment may be generally the same as the first embodiment described above, however, in this embodiment the burner 1 is arranged in a preferable manner to act as a cooking device. It will be understood, however, that the additional features of this embodiment may be used in combination with the second or third embodiments described above.

In this embodiment, a utensil support unit 54 extends circumferentially around the cylindrical body and is disposed such that a unit inner surface 55 is mounted adjacent to the outer surface 21 of the cylindrical body 2 at it's upper end 5. The lid 18 supports the unit base 56, such that the lid 18 and the cylindrical body outer surface 21 locate it in position. An upper inner portion 57 of the unit 54 is recessed and is arcuate. A reflective surface 58 is formed on the upper inner portion 57 and air holes 59 extend through the reflective surface 58 to the unit base 56 distal from the lid 18 to allow air to pass therethrough. Further, mounting portions 60 are arcuately formed about the unit upper surface 61.

Operation of the burner 1 according to the above embodiment will now be described. The burner 1 of the above embodiment operates in a similar way to the operation of the first embodiment, however, in this embodiment the utensil support unit 54 is mounted to the lid 18 and cylinder body 2. The fuel is then ignited and burns as previously discussed. Air flows through the air holes 59 and is supplied to the flame to aid fuel burning and the reflective surface 58 reflects heat and light energy produced by the burning fuel to improve the performance of the burner.

Cooking utensils, such as a saucepan, may then be placed on the mounting portions 60 so that, for example, the contents of the cooking utensil will be cooked.

The embodiment disclosed above discusses the use of the burner 1 as a cooking device. However, it will be appreciated by those skilled in the art that the burner 1 may be used to form a boiler, a cold room or a refrigeration system.

Although embodiments of the invention have been shown and described, it will be appreciated by those skilled in the art that these are preferred embodiments only and that changes may be made to these embodiments, or alternative embodiments are included, within the scope of the invention which is defined in the claims hereafter.