A FUEL BURNER SYSTEM

INTRODUCTION

This invention relates to a burner. More particularly, this invention relates to a fuel burner used in a cooking apparatus.

BACKGROUND TO THE INVENTION

Cooking appliances of the portable type that are powered by paraffin or gas has been known for many years in the state of the art.

Various types of burners are known for liquid and gas powered appliances. These include paraffin wick, pressurised paraffin and liquid petroleum gas cylinder based appliances.

The Primus stove is a pressurised paraffin appliance resulting in efficient fuel combustion. The disadvantages of this stove include:

• Preheating, often using methylated spirits, is required to start the burner.

• The paraffin fuel container is pressurised by means of a hand pump.

• The paraffin is often overheated resulting in the fuel carbonizing and blocking the jet.

The disadvantage of wick type burners include:

• They take a long time to heat up.

• The wick deteriorates quickly reducing the cooker's performance.

• Pots are left with black bases because of incomplete fuel combustion.

The applicant has described a fuel canister in South African patent number 2006/01588 which contains a paraffin/LPG mix. The LPG may contain propane and/or butane. In this patent the applicant claims that the propane, having a lower flash point, acts as a fire starter while also acting as a propellant.

OBJECTS OF THE INVENTION

It is the object of the present invention to provide a new fuel burner configuration.

It is a second object of the invention to provide a control mechanism for controlling the flow of a heating mixture from a pressurised vessel.

It is a further object of the invention to provide a gas-liquid fuel burner to be used in a cooking appliance or heating apparatus.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a burner body which includes:

- a preheating zone;

- an expansion zone and

- one or more orifice.

The preheating zone may be a substantially toroidal chamber. The preheating zone may be located upstream of the expansion zone.

Alternatively, the preheating zone may be a tube which extends at least partway around the burner, to assist in preheating a heating mixture before it is combusted.

The preheating zone and the expansion zone may be part of the same chamber.

The preheating zone and the expansion zone may be in flow communication. A conduit may connect said zones.

The conduit may extend substantially into the preheating zone.

The conduit may extend to an upper wall portion of the preheating zone.

One or more orifice may be located in or proximally the expansion zone.

In use, the orifice is located at a ceiling of the expansion zone.

The orifice may be in the form of a jet.

The heating mixture may be a mixture of liquid hydrocarbon and a combustible gas.

The heating mixture may be guided towards the preheating zone by means of one or more conduits which extend from a pressurised fuel tank wherein the heating mixture is contained.

The pressurised fuel tank may be in the form of a canister.

A combustion zone may be located above the preheating zone of the burner body. This may be termed the hat of the burner body.

The hat may include a series of perforations.

The perforations may facilitate distribution of a gasified heating mixture.

The burner body may include castellations. This may be termed the crown of the burner body.

The castellations may be disposed perimetrically, substantially vertically on the burner body.

The castellations may be configured so as to assist in control of the temperature of the burner body.

The temperatures of the preheating zone may be kept below 380°C to ensure that the paraffin in the heating mixture does not carbonize. Preferably the temperature is kept below 350 ^° C.

According to a second aspect of the invention there is provided a burner control mechanism, which include a valve and two conduits detachably secured to the valve, wherein in use, one of the conduits extends upwardly and the other is disposed at an angle thereto.

Alternatively, one of the conduits extends upwardly and the other substantially downwardly thereto.

The burner control mechanism may balance the flow of the fuel from a pressurised fuel reservoir to the burner.

The burner control mechanism may facilitate partial separation of the combustible gas from the liquid hydrocarbon.

Partial separation is achieved by the configuration of the two conduits.

According to a third aspect of the invention there is provided a burner control mechanism , which mechanism includes a needle that is engageable with a seat; wherein one of the needle and the seat is stainless steel and the other brass.

The needle may be formed from stainless steel.

The seat may be made from brass.

According to a fourth aspect of the invention there is provided a fuel burner system which includes:- - a burner body as described above;

- a control mechanism as described above; and

- a pressurised fuel reservoir containing a heating mixture of a combustible gas and a liquid hydrocarbon.

The fuel burner system may be utilised in any cooking and/or heating apparatus.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

The invention will now be described in greater detail, by way of non-limiting example only with reference to the following drawings in which:

Figure 1 shows a three-dimensional view of a burner body, according to the present invention;

Figure 2 shows a cross-sectional view of a burner body with two expansion chambers according to the present invention;

Figure 3-4 shows a front-view and a cross-sectional view along a line A-A of a control mechanism, according to a second and third aspect of the invention;

Figure 5 shows a three-dimensional view of a fuel burner system, according to a fourth aspect of the invention;

Figure 6 shows a cross-sectional view of a burner body, according to the present invention.

In Figures 1 to 6, reference numeral 10 refers generally to a burner body according to the invention. The burner body 10 includes a preheating zone in the form of a chamber 12, an expansion zone in the form of a chamber 14 and a orifice in the form of a jet 16.

The preheating chamber 12 is a toroidal cavity, as shown.

The preheating chamber 12 and the expansion chamber 14 are in flow communication with each other by means of a conduit 22.

The conduit 22 extends substantially into the preheating chamber 12, preferably to the ceiling 12b of the preheating chamber 12.

The heating mixture 24 may be a mixture including a liquid hydrocarbon and a combustible gas. Typically the combustible gas is propane and/or butane and the liquid hydrocarbon is illuminating paraffin. In the heating mixture the propane is 5 to 40 % v/v and the paraffin from about 60 to 95% v/v.

The heating mixture 24 is guided towards the preheating chamber 12 by means of two angularly disposed conduits 26a and 26b, which extend from a pressurised tank 28 wherein the heating mixture 24 is contained.

In use, the combustible gas moves at a faster rate and reaches the burner body 10 before the liquid hydrocarbon.

The liquid hydrocarbon then passes through the preheating chamber 12 and exits as a substantially vaporised hydrocarbon. The vapour is forced to exit the preheating chamber due to pressure within the preheating chamber 12. The vapour then flows through a conduit 22 to the expansion chamber 14, where it substantially gasifies and escapes through the jet 16 located at the ceiling 14b of

the expansion chamber 14, passes through the series of perforations of the hat 20 and is ignited and burns.

The expansion chamber 14 includes a baffle 42 having a first and second orifice, 44a and 44b. The inventor believes that the baffle 42 regulates the flow of gasified vapours to the jet 16.

The jet 16 includes a jet filter 46. The inventor believes that the jet filter 46 prevents liquid drops, which have not been vaporised and/or gasified, from passing throught the jet 16.

The burner body 10 includes castellations 32. This is termed the crown of the burner body 10.

The inventor believes that the castellations 32 aid in the collection of heat and heat transfer to the burner body 10. The inventor further believes that the dimensions of the castellations 32, in particular, the height of the castellations 32 controls the temperature of the preheating zone in ensuring that the preheating zone does not exceed 380 ^° C, more preferably that the preheating zone does not exceed 350 ^° C.

One or more temperature tuning rings 48 is detachably positioned on a free end of the castellations 32. The ring 48 comprises a flange 50, which the inventor believes assists in trapping the heat and deflecting said heat onto the castellations 32.

As shown in Figures 3 and 4, there is provided a burner control mechanism 34 which includes a valve 36 and two conduits 26a and 26b which are detachable connected to the valve 36.

The control mechanism balances the flow of the fuel from the pressurised fuel tank 28 to the burner body 10. Partial separation of the combustible gas and the liquid hydrocarbon is achieved by the configuration of the two conduits 26a and 26b as one of the conduits 26a extends upwardly and the other 26b downwardly.

The control mechanism includes a stainless needle 38 that is engageable with a brass seat 40.

In use, the burner operates as follows.

The control mechanism 34 is actuated and the heating mixture 24 is released. The heating mixture includes a combustible gas and a liquid hydrocarbon. This mixture is partially separated into a gas and a liquid. The gas moves at a faster rate than the liquid and moves in conduit 26a and rapidly passes through the preheating chamber 12 expansion chamber 14, jet 16 and is ignited.

The castellations 32 collects the heat generated from ignition of the combustible gas and transfers it to the burner body. Furthermore, the heat is trapped by the temperature tuning rings 48 and deflected by the flange 50 onto the castellations 32.

The liquid hydrocarbon lags slightly behind the combustible gas and passes through the hot preheating chamber 12, where the heat from the burner body 10 vaporises the liquid hydrocarbon.

The vaporised hydrocarbon exits the preheating chamber 12, flows via conduit 22 to the expansion chamber 14 where it is substantially gasified. The baffle 42 with orifice 44a and 44b regulates the flow of the substantially gasified vapour to the jet 16. The gasified vapours escapes through the jet 16, passes through the perforations of the hat 20 and burns. The jet filter 46 prevents any liquid drops that have not been vaporised and/or gasified from passing through the jet 16.

At steady state both the gas and liquid continuously pass through the preheating chamber 12.

The height of the castellations controls the temperature of the preheating chamber and maintains said temperature below 350 ⁰ C so as prevent carbonization of the paraffin in the heating mixture.

Although certain embodiments of the invention have been described herein, it will be readily appreciated to any person skilled in the art that other modifications and/or variations of the inventions are possible. Such modifications are therefore to be- considered as falling within the scope and spirit of the invention as herein described or exemplified.