GB2150642A - Gas burning devices - Google Patents

Abstract

Fuel storage and supply apparatus for a gas burning device, such apparatus comprising a first storage space 3 for pressurised gaseous fuel, a second storage space 2 for unpressurised liquid fuel, means 48, 49 for separately feeding said gaseous fuel and said liquid fuel to a gas burning device, and means 48 for directing said pressurised gaseous fuel into said liquid fuel storage space to cause said liquid fuel to be fed under pressure to said gas burning device. <IMAGE>

Description

SPECIFICATION Gas burning devices This invention relates to gas burning devices such as cookers, heaters and all manner of other such devices, particularly but not exclusively for domestic use, and has as its main object to provide an improved fuel storage and supply apparatus for such a device, and a gas burning device incorporating such apparatus.

Propane gas has been widely used as a fuel for such devices, but has considerable disadvantages in the way of the possibility of explosions and of inhaling poisonous fumes.

Liquid fuels such as kerosene and diesel oil are cheaper and safer, but they have to be heated to achieve sufficient vaporisation for complete combustion, and up to now it has been normal practice to provide an electric heater to effect at least the initial vaporisation for starting the device. Furthermore it has been necessary to provide a pump to feed the liquid fuel from the fuel tank to the burner, which pump is again electrically powered.

These requirements have motivated against the use of liquid fuels, for a number of reasons. Thus, firstly, failure of the electricity supply renders the device inoperative. Secondly it takes an undesirably long time to achieve initial vaporisation of the fuel for starting up. Thirdly the heater and the pump are expensive.

According to the present invention there is provided fuel storage and supply apparatus for a gas burning device, such apparatus comprising a first storage space for pressurised gaseous fuel, a second storage space for unpressurised liquid fuel, means for separately feeding said gaseous fuel and said liquid fuel to a gas burning device, and means for directing said pressurised gaseous fuel into said liquid fuel storage space to cause said liquid fuel to be fed under pressure to said gas burning device.

With such an arrangement an associated gas burning device may be started up on a supply of gaseous fuel, and some of the heat produced by the initial burning of the gaseous fuel may then be used to effect initial vaporisation of the liquid fuel, which is fed to the burner by the pressure of the gaseous fuel.

Thus a gas burning device may be provided in accordance with the invention which operates principally on liquid fuel but does not need either a heater for vaporisation or a pump for fuel feed.

Preferably the apparatus includes shut-off valve means for disconnecting the said gaseous fuel storage space from the liquid fuel storage space when the gas burning device is not operating, and for simultaneously disconnecting the liquid fuel storage space from the gas burning device.

Preferably an adjustable regulator is provided at the outlet from said first storage space.

Preferably the said gaseous fuel storage space is defined by a housing contained within the said liquid fuel storage space.

The scope of the invention also extends to apparatus as set forth above in combination with a gas burning device, and including a three-way control valve for selectively feeding said gaseous and liquid fuels to a burner of the said device.

Preferably the said control valve is also adapted to regulate the flow of each of the said fuels.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a vertical axial cross-sectional view of a fuel storage and supply apparatus according to the invention; Figure 2 is a vertical axial cross-sectional view of the burner head of a gas burning device for use with the apparatus of Fig. 1; Figure 3 is a perspective view, partly cut away, of a heating plate of the burner head of Fig. 2; Figure 4 is a perspective view of a cover plate of the burner head; Figure 5 is a perspective view of the top cover of the burner head, formed with a ring of flame apertures; Figure 6 is a perspective view of a gas burning device incorporating the burner head of Figs. 2 to 5; Figure 7 is a vertical axial cross-sectional view of a shut-off valve of the apparatus of Fig. 1; and Figure 8 is an axial cross-sectional view, and an end view, of a three-way control valve of the gas burning device of Figs. 2 to 6.

Referring first to Fig. 1, a fuel storage and supply apparatus according to the invention comprises a tank 1 defining a first storage space 2 for liquid fuel and also enclosing a cylindrical housing defining a second storage space 3 for pressurised gaseous fuel. The storage spaces 2 and 3 are entirely separated from each other within the tank 1.

A gas burning device according to the invention preferably uses liquid fuel in the form of a hydrocarbon with a boiling point in the range 170 to 350"C and with a specific gravity of 0.8 to 0.9. A preferred form of pressurised gaseous fuel is butane having a vapour pressure of 1.9 kg/cm2 at 20"C, or isobutane with a vapour pressure of 3 kg/cm2 at 20"C; of course the vapour pressure of the liquid fuel may vary with room temperature.

As the gaseous fuel used produces a substantial pressure at room temperature, it can be used to feed the liquid fuel under pressure from the storage space 2 to an associated gas burning device.

The apparatus of Fig. 1 incorporates a regulator for the gaseous fuel, comprising a valve stem 41 slidable in a tube 4 and carrying a valve member 42 urged to closing position by a compression spring 43. At the top end of the valve stem 41 is an adjusting spring 44 and an adjusting knob 45 screw-threadedly mounted on the tube 4 at 46. Adjustment of the regulator by way of the knob 45 controls the flow of gaseous fuel from the storage space 3 to a gaseous fuel exit 47. Connected to the exit 47 is a gaseous fuel feed pipe 48 leading to a fuel control valve 9 (Figs. 2 and 8) of the gas burning device, to be described below. The gaseous fuel feed pipe 48 also communicates with the liquid fuel storage space 2 via an opening in the roof of the tank 1.Mounted coaxially within the pipe 48 is a liquid fuel feed pipe 49 connected to a liquid fuel supply pipe 5 extending to the bottom of the storage space 2 where it is provided with a fiiter inlet 51. A shut-off valve 6, shown in more detail in Fig. 7, is operable to disconnect both the gaseous fuel feed pipe 48 and the liquid fuel feed pipe 49 from the interior of the liquid fuel storage space 2 when the gas burning device is not in use.

Referring now to the burner head of the gas burning device, shown in Figs. 2 to 6 and Fig. 8, this includes an annular evaporating chamber 7 for liquid fuel (see Figs. 2 and 3) mounted around the inner perimeter of an annular heating plate 8. Connected to the evaporating chamber 7 are an inlet pipe 71 and an outlet pipe 72, the inlet pipe connected to the control valve 9 previously mentioned. Having passed through the control valve 9 and the inlet pipe 71, liquid fuel flows through the evaporating chamber 7 where it is heated and evaporated and then passes through the outlet pipe 72 to the fuel supply nozzle 10 previously mentioned, and thence to a fuel/air mixing pipe 81 where it mixes with ambient air and burns in a chamber defined by a substantially conical cover plate 82 and an inverted cup-shaped housing 11 formed with flame apertures 111 leading into the heating plate 8.The cover plate 82 is formed with apertures 83 to convey sufficient heat to the internal annular chamber defined above the evaporating chamber 7, to effect evaporation of the liquid fuel therein.

The control valve 9 is a three-way valve which selectively delivers either gaseous fuel from the pipe 48 to the nozzle 10 via asupply pipe 101 (i.e. not via the vaporising chamber), or liquid fuel from the pipe 49 to the fuel nozzle 10 via the vaporising chamber, and is also operative to control the rate of flow of each of the fuels. A control knob 91 of the valve 9 is exposed at the front of a typical gas burning device of the invention, illustrated in Fig. 6, as is an ignition switch 1 2. Both the valve 9 and the ignition switch 1 2 are of a conventional nature.

The manner of operation of the illustrated apparatus will now be described.

The adjusting knob 45 is first turned to open the outlet from the gaseous fuel chamber 3 and the control valve 6 is then opened to admit gaseous fuel into the top of the liquid fuel chamber 2 and also to connect the liquid fuel chamber to the burner head via the liquid fuel feed pipe 49. Admission of pressurised gaseous fuel into the liquid fuel chamber 2 causes liquid fuel to be fed up the supply pipe 5 and through the feed pipe 49 to the three-way control valve 9 from whence it may flow to the evaporating chamber 7. The valve 9 is now adjusted to the position to feed gaseous fuel to the supply pipe 101 and thence to the fuel nozzle 10 and the ignition switch 1 2 is now operated to ignite the gaseous fuel in the fuel/air mixing pipe 81.Burning of the gaseous fuel now heats the evaporating chamber 7 and this is continued for between 30 and 60 seconds to vaporise the liquid fuel in the evaporating chamber and to ensure that the chamber is hot enough to continue to vaporise liquid fuel when this is now supplied by adjusting the control valve 9 to the position for liquid fuel supply. This shuts off the gaseous fuel supply and vaporised liquid fuel is now burned instead, the supply of liquid fuel being thereafter continued under the pressure provided by the gaseous fuel in the liquid fuel chamber 2. Of course, as the gaseous fuel is now cut off from the burner head all of its pressure is available to feed liquid fuel to the burner from the liquid fuel storage space 2, and operation of the gas burning device continues with liquid fuel from now on.

It will thus be seen that apparatus according to the invention, at least in its preferred and illustrated embodiment described above, has a number of advantages over known devices. Thus firstly it operates mainly on lowgrade liquid fuels such as kerosene, diesel oil and the like, which makes its operation safer and also cheaper. Secondly the apparatus does not need to incorporate a heater for vaporising the liquid fuel nor a pump to feed the same, so that it can operate at any location, whether or not an electric power supply is available. Of course, the fact that neither a heater nor a pump is any longer needed makes the apparatus substantially cheaper than earlier proposals. Thirdly, the apparatus is of a rugged and simple construction which increases its useful life and decreases its likelihood of breaking down. In addition it is very simple to operate.

Claims (11)

1. Fuel storage and supply apparatus for a gas burning device, such apparatus comprising a first storage space for pressurised gaseous fuel, a second storage space for unpressurised liquid fuel, means for separately feed ing said gaseous fuel and said liquid fuel to a gas burning device, and means for directing said pressurised gaseous fuel into said liquid fuel storage space to cause said liquid fuel to be fed under pressure to said gas burning device.

2. Apparatus as claimed in claim 1, including shut-off valve means for disconnecting the said gaseous fuel storage space from the liquid fuel storage space when the gas burning device is not operating, and for simultaneously disconnecting the liquid fuel storage space from the gas burning device.

3. Apparatus as claimed in claim 1 or 2, wherein an adjustable regulator at the outlet from said first storage space.

4. Apparatus as claimed in any of claims 1 to 3, wherein the said gaseous fuel storage space is defined by a housing contained within the said liquid fuel storage space.

5. Apparatus as claimed in claim 1, substantially as hereinbefore described with reference to the accompanying drawings.

6. Apparatus as claimed in any of claims 1 to 5, in combination with a gas burning device, and including a three-way control valve for selectively feeding said gaseous and liquid fuels to a burner of said device.

7. Apparatus as claimed in claim 6, wherein said control valve is also adapted to regulate the flow of each of said fuels.

8. Apparatus as claimed in claim 6 or 7, wherein the said burner includes an evaporating chamber for liquid fuel, said control valve being arranged to feed liquid fuel to the burner head via said evaporating chamber.

9. Apparatus as claimed in claim 8.

wherein the said evaporating chamber is an annular chamber which surrounds a central fuel/air mixing pipe of the burner and is itself surrounded by a flame ring.

10. Apparatus as claimed in claim 9, wherein the said fuel/air mixing pipe is connected to and surrounded by a substantially conical cover plate forming the bottom of a housing whose cylindrical side wall is formed at its lower region with a ring of flame apertures opening to said heating plate.

11. Apparatus as claimed in claim 6, substantially as hereinbefore described with reference to the accompanying drawings.