GB2221026A

GB2221026A - Gas burner

Info

Publication number: GB2221026A
Application number: GB8912886A
Authority: GB
Inventors: Simon John Froggatt
Original assignee: Glow Worm Ltd
Current assignee: Glow Worm Ltd
Priority date: 1988-06-04
Filing date: 1989-06-05
Publication date: 1990-01-24
Anticipated expiration: 2009-06-05
Also published as: GB8912886D0; GB2221026B; GB8813237D0

Abstract

A live fuel effect is obtained utilizing a gas burner by introducing into a main gaseous fuel supply having a predetermined gas/air ratio an additional gas-rich supply, mixing the main and additional supplies and igniting the mixture at the burner outlet. The gas-rich supply, which may be gas alone is cut off to burn off any soot produced. Preferably the burner comprises a plurality of selectively usable burner sections 6, 7 the main gaseous fuel supply being selectably introduced into one or more of the sections from corresponding aeration box 10A, 10B, the gas-rich supply being continuously introduced from pipe 16 and means an opening 18 being provided to draw the gas-rich supply into the other section of the burner when the main gaseous fuel supply cut off from the one burner by valve 14. The main supply from gas injections 11A, 11B and air inlets 15A, 15B of aeration boxes 10A, 10B mixes in tubes 8, 9. <IMAGE>

Description

Gas Burners This invention relates to gas burners and is especially, but not exclusively, applicable to gas burners for use in so-called "live fuel effect" fires, that is to say gas fires which are provided with imitation fuel and are designed in use to produce a visual flame effect simulating that attained by an open coal or log fire.

The production of an aesthetically satisfactory live flame effect requires the use of a gas-rich gas/air mixture but this brings with it the disadvantage that the resulting flames give rise to soot which deposits on the simulated fuel elements causing restriction to flow of combustion products to the flue. As a result the burner requires to be so constructed that it may be periodically operated using a less rich gas/air mixture which burns off accumulated soot.

Previous attempts to produce such burners have employed a main burner which produces flames for heating purposes and an associated auxiliary burner in which an over-rich gas/air mixture is burned producing cooler flames of a different character which are directed into the main flame and alter the visual effect. By cutting out the auxiliary burner periodically the main burner may be operated alone to burn off accumulated scot.

Such arrangements however do not produce a wholly realistic live fuel effect and suffer from other disadvantages. Particular problems arise in the construction of burners having two or more control settings in which different sections of the burner are operative since the auxiliary burner must be confined to one section or multiple auxiliary burners must be provided corresponding to the number of main burner sections. This considerably complicates the construction of such burners and substantially increases their cost.

It is an object of the present invention to obviate or mitigate these disadvantages.

According to one aspect of the invention there is provided a method of producing a live fuel effect utilizing a gas burner comprising introducing into a main gaseous fuel supply having a predetermind gas/air ratio, an additional gas-rich supply, mixing said main and additional supplies and igniting same at the burner outlet.

As applied to a burner comprising a plurality of selectively usable sections the method advantageously comprises selectively introducing said main gaseous fuel supply into one or more of said sections, continuously introducing said gas-rich supply and constraining said gas-rich supply to flow only into the section or sections of the burner into which said main gaseous fuel supply is introduced at any predetermined time.

Preferably said additional gas-rich supply is constrained to flow into the appropriate section or sections by suction generated by the flow of said main gaseous fuel supply thereinto.

According to a further aspect of the invention there is provided a gas burner comprising a housing defining a burner chamber, means for introducing into said chamber a main gaseous fuel supply having a predetermind gas/air ratio and an auxiliary gas-rich supply, means for mixing said main and auxiliary supplies, and ignition means for igniting the mixture at the burner outlet.

Preferably said housing comprises a plurality of chambers each of which defines a burner section, the burner including control means operable to selectively admit said main gaseous fuel supply to one or more of said sections, and to admit said auxiliary gas-rich fuel supply to the burner, and means operable to constrain essentially all of said auxiliary fuel supply to flow into the burner section or sections into which said main gaseous fuel supply is introduced at any one time.

Preferably said main fuel supply is introduced into the or each burner section from a mixing chamber in which gas and air are mixed, the mixing chambers associated with each of said sections being interconnected such that during operation the flow of fuel through the mixing chamber or chambers in use at any given time produces a suction effect acting on the chamber or chambers which are inoperative, whereby essentially all of said auxiliary fuel supply is drawn into the operative burner section or sections.

Preferably each mixing chamber comprises a tube into which air and gas are introduced from an aeration box, said means for introducing auxiliary fuel comprising a pipe or tube communicating with both or all of said mixing chambers and provided with an outlet in each chamber and said chambers being interconnected by means of an aperture or apertures between the associated aeration boxes.

According to a further aspect of the invention there is provided a gas burner comprising a housing defining one or more burner sections each connected through a mixing chamber to an aeration box having inlets for main gas and air supplies, and auxiliary fuel supply means at or upstream of said mixing chamber or chambers, such that in use an auxiliary fuel supply may be introduced into the main fuel supply to modify the flame characteristics of the burner to produce a live fuel effect.

The invention also provides a gas-fired heating appliance incorporating a burner as aforesaid.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing which is a diagrammatic crosssection through a burner construction according to the invention.

Referring to the drawing the burner is adapted for use in a live fuel effect fire and comprises an elongated casing 5 divided by internal partitions into a central burner section 6 and an outer burner section 7.

The upper surfaces of both sections are perforated and constitute a flame strip at which ignition of gaseous fuel supplied to the burner takes place. The casing is constructed of metal and is gas tight save for the perforated flame strip.

Main gas supply tubes 8 and 9 enter the burner casing 5 through one end wall, the tube 8 communicating with the outer burner section 7 and the tube 9 passing through the outer section and communicating with the central section 6. The tubes 8 and 9 are arranged to be supplied in use with a gaseous fuel mixture from an aeration box 10 having an upper section 10A communicating with the tube 9 and a lower section lOB communicating with the tube 8. Injectors 11A and llB are mounted in the end wall of the aeration box 10 opposite to that from which the tubes 8 and 9 extend, the injectors being supplied in use with gaseous fuel through pipes 12A and 12B from a main gas supply pipe 13 under control of a valve or tap 14.

Apertures 15A and 15B are formed in one side wall of the aeration box 10 and permit entry of air indicated by the arrows "A" for mixing with the gas supplied from the injectors 11A and11B. The tubes 8 and 9 constitute mixing tubes within which the gas and air from the box 10 are mixed before passing to the chambers 6 and 7 for ignition at the upper perforated surface of the burner.

An auxiliary or bleed gas supply pipe 16 extends into each of the tubes 8 and'9 and is provided with outlet openings 17A, 178 in each tube. The pipe 16 is connected to the main gas supply pipe 13 via the control valve or tap 14. Since the outlet openings in the pipe 17 are located in the tubes 8 and 9 in which mixing of gas and air take place, the additional gas supplied through the piepe 16 is mixed with the main gas and air supply.

An aperture 18 is provided in the partition 10C which divides the aeration box 10 into the upper and lower sections 10A and 10B, the aperture 18 forming a connection between the two sections the function of which will be described hereafter.

In operation of the burner the valve 14 may be positioned in any one of six positions, one being an inoperative or "off" position in which the valve is closed and supply of gas to the burner from the pipe 13 is cut off, and the other five positions being operative positions. In the first operative position gas is supplied to the upper section 10A of the aeration box 10 but not to the lower section 10B or to the bleed pipe 16. In the second operative position gas is supplied to the upper section 10A of the aeration box and also to the bleed pipe 16. In the third and fourth operative positions gas is supplied at different rates of flow to both sections 10A and 10B and to the bleed pipe 16.The fifth operative position is a "burn-off" position in which gas is supplied to the top and bottom sections 10A and 10B of the aeration box but not to the bleed pipe 16.

In the second operative position in which gas is supplied only to the upper chamber 10A of the air box 10, the velocity of gas leaving the injector 11A draws air into the box through the aperture 15A, the gas and air leaving the aeration box and entering the mixing tube 9 where they are intimately mixed together. Within the tube 9 additional gas introduced through pipe 16 is mixed with the gas and air from the box 10A and this gas enriched mixture is delivered to the section 6 of the burner where it is ignited and burnt at the upper surface.Due to the venturi effect produced by the velocity of gas and air passing through the upper section 10A of the box 10, gas introduced into the lower tube 8 from the pipe 16 is drawn through the lower section lOB of the box 10 and into the upper section 10A through the aperture 18, from whence it is mixed in the tube 9 with the gas and air introduced from the box 10 and from the upper aperture 17A of the pipe 16. In this way although gas is continuously supplied to tube 8 through pipe 16 the gas is diverted into the upper tube 9 and hence the central section of the burner where it is combusted.

In the third and fourth operative positions in which gas is introduced into both sections of the box 10 from the injectors 11A and 11B, there is no transfer of auxiliary gas through the aperture 18 since gas emitted from the lower aperture 178 of pipe 16 is entrained with the fuel/air mixture passing from tube 8 into the outer burner section 7 and gas emitted from the upper aperture 17A of the pipe 16 is entrained with the gas and air passing through tube 9 into the central burner section 6.

The injectors 11A, llB and the apertures 15A, 15B in the box 10 are designed to produce the desired ratio of gas to air in the main gaseous fuel mixture introduced into the tubes 8 and 9 and for burning in the rospecLJve burner scions. The auxiliary supply introduced through pipe 16 is substantially non-aerated and it has been found that mixing of this supply with the main gas/air mixture to produce a gas-rich fuel for ignition at the upper surface of the burner results in production of a particularly satisfactory live flame effect. Since the mixture is gas-rich but is essentially uniformly mixed, the desired effect is attained over the whole width of the burner which improves on previous proposals where additional flames have been produced at spaced locations.Although this produces a reasonably satisfactory flame it has a generally fixed pattern which produces a less authentic effect.

Due to the slightly rich gas/air fuel mixture, a degree of sooting may eventually take place. This can however be readily burnt off by moving the control valve 14 to the "burn off" position referred to previously in which the gas supply to pipe 16 is cut off while the supply to pipes 12A and 128 is maintained, whereby to produce a less rich mixture which will burn off sooting.

Various modifications may be made without departing from the invention. For example the degree of aerat ion of the main gas supply may be varied as desired and the auxiliary supply may be unaerated or aerated to a lesser degree as desired. The invention may also be applied to burners incorporating a single burner chamber or three or more such chambers. Any suitable means of ignition of the gaseous fuel mixture may be provided and the means for supplying and mixing the main and auxiliary gas supplies may be altered. Moreover while in the arrangement described the additional gas supply is introduced into the mixing tubes it could in some circumstances be introduced into the respective sections of the aeration box or into a common aeration box connected to both or all the mixing tubes.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. A method of producing a live fuel effect utilizing a gas burner comprising introducing into a main gaseous fuel supply having a predetermined gas/air ratio, an additional gas-rich supply, mixing said main and additional supplies and igniting same at the burner outlet.

2. A method according to claim 1 applied to a burner comprising a plurality of selectively useable sections, the method comprising selectively introducing said main gaseous fuel supply into one or more of said sections, continuously introducing said gas-rich supply, and constraining said gas-rich supply to flow only into the section or sections of the burner into which said main gaseous fuel supply is introduced at any predetermined time.

3. A method according to claim 2 wherein said additional gas-rich supply is constrained to flow into the appropriate section or sections by suction generated by the flow of said main gaseous fuel supply thereinto.

4. A method according to any of claims 1 to 3 wherein said additional gas supply is non-aerated.

5. A method of producing a live fuel effect substantially as hereinbefore described.

6. A gas burner comprising a housing defining a burner chamber, means for introducing into said chamber a main gaseous fuel supply having a predetermined gas/air ratio and an auxiliary gas-rich supply, means for mixing said main and auxiliary supplies, an71ignitics means for igniting the mixture at the burner outlet.

7. A gas burner according to claim 6 wherein said housing comprises a plurality of chambers each of which defines a burner section, the burner including control means operable to selectively admit said main gaseous fuel supply to one or more of said sections, and to admit said auxiliary gas-rich fuel supply to the burner, and means operable to constrain essentially all of said auxiliary fuel supply to flow into the burner section ar sections into which said main gaseous fuel supply is introduced at any one time.

8. A gas burner according to claim 7 wherein said main fuel supply is introduced into the or each burner section from a mixing chamber in which gas and air are mixed, the mixing chambers associated with each of said sections being interconnected such that during operation the flow of fuel through the mixing chamber or chambers in use at any given time produces a suction effect acting on the chamber or chambers which are inoperative, whereby essentially all of said auxiliary fuel supply is drawn into the operative burner section or sections.

9. A gas burner according to claim 8 wherein each mixing chamber comprises a tube into which air and gas are introduced from an aeration box, said means for introducing auxiliary fuel being located at or upstream of said mixing chambers.

10. A gas burner according to claim 9 wherein said means for introducing said auxiliary fuel comprises a pipe or tube communicating with both or all of said mixing chambers and provided with an outlet in each chamber and said chambers being interconnected'by means of an aperture or apertures between the associated aeration boxes.

11. A gas burner comprising a housing defining one or more burner sections each connected through a mixing chamber to an aeration box having inlets for main gas and air supplies, and auxiliary fuel supply means at or upstream of said mixing chamber or chambers, such that in use an auxiliary fuel supply may be introduced into the main fuel supply to modify the flame characteristics of the burner to produce a live fuel effect.

12. A gas burner according to claim 11 wherein said auxiliary fuel supply means communicates with the or each mixing chamber.

13. A gas burner according to claim 11 or 12 comprising a plurality of burner sections, in which the mixing chambers associated with each of said sections are interconnected.

14. A gas burner according to claim 13 wherein said mixing chambers are interconnected by way of an aperture or apertures between the associated aeration boxes.

15. A gas burner substantially as hereinbefore described with reference to the accompanying drawing.

16. A gas fired heating appliance incorporating a burner according to any of claims 6 to 15.

17. Any novel subject matter or combination including novel subject matter herein disclosed in the foregoing specification or claims and/or shown in the drawings, whether or not within the scope of or relating to the same invention as any of the preceding claims.