GB2328735A

GB2328735A - Pilot burners

Info

Publication number: GB2328735A
Application number: GB9818717A
Authority: GB
Inventors: Kulwant Mandir
Original assignee: Valor Ltd
Current assignee: Valor Ltd
Priority date: 1997-08-30
Filing date: 1998-08-28
Publication date: 1999-03-03
Anticipated expiration: 2018-08-28
Also published as: GB9818717D0; GB9718496D0; GB2328735B

Abstract

A burner for a gas appliance, the burner comprising an elongate passage (5, 7) which changes in direction along its length and through which gas can pass towards an open end (13) which, in use, forms a burner outlet. An additional burner arrangement, preferably in the form of a slot (15) (fig.3A) which extends axially of the elongate passage, extends from the burner outlet (13) along the passage (7) for at least part of the length of said passage (7). Thus, in use, a single flame (21, 23) burns at the burner outlet (13) and extends as a subsidiary part (23) of the flame along slot (15), this subsidiary part (23) of the flame heating a thermocouple (17) of a flame failure device to thus shut off the gas supply in the event that the subsidiary part (23) changes or dies as a result, for example, of oxygen depletion. The additional burner may alternatively comprise a series of perforations, and/or a series of slots extending axially or transversely of the elongate passage.

Description

DESCRIPTION IMPROVEMENTS RELATING TO BURNERS The present invention relates to a burner.

More particularly the present invention relates to a burner for use in a pilot burner unit of a gas fired appliance, especially in a pilot burner unit for use in a gas fired heater for heating open spaces in private homes, restaurants, hotels or offices.

Certain known burners for use in pilot burner units comprise a hollow tubular member with one end connected to a gas supply line and the other open end serving as a burner outlet, the hollow tubular member being arranged so that a flame burning at or in the region of the burner outlet heats a thermocouple. The e.m.f. produced by the heated thermocouple is applied to a solenoid valve in the gas supply line so that when the solenoid is physically opened, usually against a spring, to allow gas to flow to the burner, and when the thermocouple has been heated to a sufficient temperature to produce an adequate e.m.f. the solenoid valve is held open. Should the flame fail ie.

become extinguished for whatever reason, the solenoid valve will close and shut off the gas supply to the pilot burner and to any main burners of the appliance.

The use of pilot burners in gas fired heaters has been practised for many decades and the pilot burners have been adapted to respond to a depletion of oxygen for at least 30 years. This is usually done by specifying the physical construction of the said tubular member, the gas supply rate and the primary air so that the pilot flame is just stable under normal atmospheric and operating conditions. In the event of a change in the gas supply pressure or a reduction in the surrounding oxygen level, the flame becomes unstable, and if conditions continue to deteriorate the flame will go out and hence cause the thermocouple to cool and the solenoid valve to close.

Oxygen depletion systems (ODS) utilising a burner as described hereabove, are usually disposed with the tubular member vertical to thus give a vertical flame. Alternatively the pilot flame may be horizontal or at an angle to the vertical.

Further, the pilot burner may be designed to produce more than one flame. The advantage of using a multiflame ODS is to use the main flame to reach across the top of the main burners whilst the second smaller flame keeps the thermocouple hot and away from the heat generated by a main burner.

However, to ensure that during abnormal conditions the flame heating the thermocouple is extinguished first, is very difficult as this requires balancing of the gas passages during manufacture. As a consequence a repeatable performance is not always obtainable and often unusual behaviour occurs when the unit reaches a high temperature ie. flames cut off giving a false shutdown.

The aim of the present invention is to provide a burner which can be used as an ODS pilot burner, which has a single flame that does not require special balanced gas ways in order to function as desired, but which retains the advantages of a multiflame ODS.

According to the present invention there is provided a burner for use in a gas appliance, the burner comprising an elongate passage which changes direction along its length and through which gas can pass towards an open end which, in use, forms a burner outlet, an additional burner arrangement being formed in a wall of the elongate passage, the additional burner arrangement extending from the burner outlet along the said passage for at least part of the length of said passage.

Thus, in use, a single flame will burn at the said burner outlet and continue along the said additional burner outlet, so that when used in an ODS, the main part of the flame extending from the said burner outlet will serve to ignite the main burner of an appliance, whilst away from the heat of the said main burners, the subsidiary part of the flame extends along the additional burner arrangement and heats a thermocouple connected to a flame failure valve ie. solenoid valve, in the gas supply line. As and when gas pressure varies or there is oxygen depletion the subsidiary part of the flame will first distort causing the solenoid valve to close.

In one embodiment of the present invention the elongate passage is provided by a part curved or angled hollow tube, one end region of which is preferably arranged vertically and connected to a gas supply. The additional burner arrangement extends from the other end of the tube, which other end forms said burner outlet, along the length of the angled or part curved portion of the tube and is preferably in the form of an axially extending slot in the upper region of the wall of the tube. Preferably the slot extends back to a location over the longitudinal axis of the vertically arranged said one end region of the tube. As an alternative to the continuous slot, a series of holes or small slots (transverse or axially of the tube) may form the said additional burner arrangement.

In another embodiment of the present invention the elongate passage is formed in a main body of the burner and in a hollow elongate tubular member which extends out from said main body at an angle to the part of the passage in said main body. The free end of the hollow tubular member forms the burner outlet, with a slot extending from said burner outlet axially of the elongate tubular member, forming said additional burner arrangement. As an alternative to the continuous slot a series of small holes or small slots (transverse or axially of the tubular member) may form the additional burner arrangement.

The present invention thus provides a burner suitable for use in an ODS, the burner having the advantages of a known multi flame ODS without the disadvantage, balancing of the gas passages being unnecessary.

The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a view of one embodiment of the present invention; Fig. 2 is a further view of the embodiment of Fig. 1; and Fig. 3a and 3b are schematic illustrations of the burner of Fig. 1 and 2, constructed in accordance with the present invention, and in operation, respectively.

Fig. 4 is a rear view of another embodiment of the present invention in combination with a thermocouple and igniter; Fig. 5 is a plan view of the combination shown in Fig. 4; Fig. 6 is a view of one side of the combination shown in Figs. 4 and 5; and Fig. 7 is an axial cross-sectional view of the other side of the burner embodiment included in Fig. 6.

The embodiment of the present invention illustrated in Figs. 1 to 3, primarily comprises an elongate passage formed by an elongate hollow tube 1 which is curved or bent at an angle in one region 3 along its length to form two elongate sections 5, 7 which are connected to each other though angled to each other.

One elongate section 5 of the tube 1 is sealingly secured in a body 9 of the gas burner, and is thereby connected to a gas supply line 11.

The other elongate section 7 has an open free end which forms a burner outlet 13. A slot 15 extends in the upper section of the wall of this other elongate section 7, from the burner outlet 13 axially of this elongate section 7 back to the said curved region 3 so that the slot 15 extends at least over the axis of said one elongate section 5, the slot 15 forming an additional burner arrangement. As an alternative to the continuous slot 15 a series of perforations or small slots can be used.

Adjacent to the curved region 3 of the tube 1 a thermocouple 17 is mounted on a bracket 10 which also supports the burner body 9 and an igniter 19. In use with gas passing along the tube 1, the igniter 19 is energised to cause the gas to burn as it issues from the burner outlet 13 and the slot 15. The main position 21 of the flame (see Fig. 3b) burns above the outlet 13, and is used to ignite main burners (not illustrated) of the gas appliance in which the burner of the present invention is installed. A subsidiary portion 23 of the flame burns above the slot 15 and heats the thermocouple 17. This subsidiary portion 23 of the flame is enhanced at the end of the slot 15 remote from the burner outlet 13 by this region of the slot 15 being in line with elongate section 5 of tube 1 so that undeflected gas under pressure issues from this region of the slot. However the slot can be shorter in length to meet desired performance characteristics.

In use, any variation in gas pressure or depletion of oxygen will initially result in the subsidiary portion 23 of the flame distorting or diminishing so as to disengage from the thermocouple, thus allowing the thermocouple 17 to cool so that a flame failure valve ie. solenoid valve (not illustrated) is closed, thereby shutting off the gas supply to the burner of the present invention and the said main burner (not illustrated).

In another embodiment of the present invention illustrated in Figs. 4 to 7 of the accompanying drawings, an angled passage 25, 27 for the passage of gas is formed by an elongate passage section 25 in a main body 29, and a further elongate passage section 27 formed in an elongate hollow tubular member 31 which extends out from the main body 29. The passage section 25 in the main body 29 is, in use, arranged vertically with the tubular member 31 extending out from the main body 29 at an angle to the vertical. The open free end of the hollow tubular member 31 forms a burner outlet 33 and an open slot 35 extends from the burner outlet 33 axially along the upper section of the tubular member 31 back to the main body 29. The open slot 35 forms an additional burner arrangement. Alternatively, in place of the slot 35 a series of perforations and/or small slots (not illustrated), transverse to or coaxial with the tubular member 31, can be provided.

As in the previous embodiment a thermocouple 37 and an igniter 39 are mounted on a support bracket 30 , together with the main body 29, so as to ignite and sustain a single flame which burns over the burner outlet 33 and the additional burner arrangement formed by the slot 35. Should there be a variation in gas pressure or oxygen depletion in the surrounding area, the subsidiary portion of the flame burning over the additional burner arrangement ie slot 35, will diminish or die allowing the thermocouple 37 to cool and to thus shut off the gas supply to all burners in the appliance.

The present invention thus provides a burner suitable for an oxygen depletion system with the advantages of a multi flame burner but with simplified manufacturing methods.

Claims

1. A burner for use in a gas appliance, the burner comprising an elongate passage which changes direction along its length and through which gas can pass towards an open end which, in use, forms a burner outlet, an additional burner arrangement being formed in a wall of the elongate passage, the additional burner arrangement extending from the burner outlet along the said passage for at least part of the length of said passage.

2. A burner as claimed in claim 1, in which the elongate passage is formed by a part curved or angled hollow tube, comprising two elongate sections integrally connected together.

3. A burner as claimed in claim 2, in which one end region of the elongate passage is adapted to be connected to a gas supply and the additional burner arrangement extends from the other end of the tube, which other end forms the burner outlet, along part of the length of said tube.

4. A burner as claimed in claim 3, in which said one end region of the tube is, when ready for use, arranged vertically or substantially vertically, with the other end region of the tube being thus angled to the vertical, said additional burner arrangement extending from the burner outlet for at least part of the length of the section of the hollow tube which is angled to the vertical.

5. A burner as claimed in claim 3, in which said additional burner arrangement extends from the burner outlet back along the tube to a location over the longitudinal axis of the vertically arranged said one end region of the tube.

6. A burner as claimed in claim 1, in which the elongate passage is formed in a main body of the burner and in a hollow elongate tubular member which extends out from said main body at an angle to the part of the passage in said main body.

7. A burner as claimed in claim 6, in which the free end of the hollow elongate tubular member forms the burner outlet and said additional burner arrangement extends from the burner outlet back along the hollow elongate tubular member.

8. A burner as claimed in claim 7, in which said additional burner arrangement extends from the burner outlet back along the hollow elongate tubular member to said main body.

9. A burner as claimed in any one of the preceding claims, in which said additional burner arrangement comprises an axially extending slot, a series of perforations, and/or a series of slots extending transversely or axially of the elongate passage.

10. A burner as claimed in any one of the preceding claims, in combination with a thermocouple and igniter which are arranged in the vicinity of said additional burner arrangement.

11. A burner as claimed in claim 10, in which the burner outlet is located in the vicinity of a gas burner for a gas appliance, so that said burner can operate as a pilot burner or as an oxygen depletion sensor.

12. A burner for use in a gas appliance, constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.