GB2186961A - Gas burner - Google Patents

Abstract

To avoid the difficulty of safely separating the gas supply in duplex gas burners, a constructionally simple duplex burner is formed from two flat burner elements arranged side by side, flame ports in one element being at least largely offset longitudinally relative to the ports in the other element. <IMAGE>

Description

SPECIFICATION Gas Burner The invention relates to elongate gas burners with separate gas supply to different length portions thereof.

Conventionally, radiant gas fires comprise a vertical or inclined panel of refractory material above an elongate horizontal burnertube having one or more rows offlame ports along its top edge. In orderto allow the burnerto be operated efficiently with low fuel consumption itiscommontoarrangeforthe burnertubeto be divided lengthwise into a numberof modules, the supply of gas to adjacent modules being independently controlled. Thus in a simple case the burner is divided into three lengthwise modules, the two outermost modules being supplied with gas via a first, controlled, path whilst the middle module is supplied via a different path contolled independently of the first mentioned path.The controls are arranged so thatwhen only low heat output (and gas consump- tion) is required, all ofthe gas is supplied to the middle module, and the outer modules become supplied only when there is an increased supply of gas. In more complex cases the burner may be divided into four or five lengthwise modules.

Conventional constructions require the supply of gas to an intermediate moduleto pass through a plenum chamber connected to outer modules, and it is importantfrom a safety aspect that leakage from a supplied module to a nominallyunsupplied module be avoided. From a design point of view it is also a requirementthatthe unit shalt be kept as slim as possibllee. These requirements have in the past caused problems which have not been satisfactorily resolved.

According to one aspect ofthe present invention, therefore, there is provided an elongate burner having flame ports along its length, the ports being divided into at leasttwo, independently supplied, groups separated from one another laterally ofthe burner.

The ports of one group are preferably at least largely separated from those ofthe other group orgroups lengthwise of the burner, but they may if required overlap. Where the groups of ports overlap, individual ports of respective groups may be mutally inclined so that flames from said individual ports impingeto give a "flame effect".

According to a second aspect ofthe invention there is provided an elongate burner having flame ports along its length comprising at least two elongate and independently supplied burner elements arranged side by side and each having at least one group of flameports,theflameportsofone burner element being at least largely offset longitudinally relative to the flame ports ofthe or each other burner element.

Embodimentsofthe invention will now be described by way of example and with. reference to the ampaatingi drawings ofwhich:- Figure 1 shows one embodiment of a burner in side elevation; Figure 2 shows the burner of Figure 1 viewed from the other side; Figures 3and 4showthe burner of Figure 1 respectively in plan and end elevation; Figure 5 is a section along lines A-A of Fig. 2.

Figure 6 is a side elevation of a second embodiment; Figure 7 shows the burner in Fig. 6 in plan; Figures 8 and 9 show the burner of Fig. 6 in end elevation.

As shown particularly in Figures 3 and 5, the burner of the first embodiment comprises two discrete burner elements 1,2 of equal length and arranged parallel with one another. Each element is formed essentially of a single sheet of suitable material such as stainless steel, pressed to define a plenum chamber and a gas supply channel, as will be described below.

As sshown in the drawings the burner comprises an enantiomorphic pair offlat-backed elements 1,2 arranged back to back. Burner element 2 comprises a single sheet 11 of stainless steel folded at the lower edge 41 to provide a generally flat back plate 6 and a front sheet 4. The back plate 6 is bent towards its upper edge to form a slightly convex substantially horizontal portion 8 and terminate in an outwardly projecting flange 10.

The flange 10is enclosed in a gas-tight manner by the 1800 fold 15 of the front sheet 4which is arranged generally parallel to the plate 6 but over areas 12 and 18 is spaced from the back plate 6 whilst along line 16 the sheet 4 approaches closely to the back plate 6.

The spaced portion 18 of the sheet 4 defines together with the upper part ofthe back plate 6, the horizontal portion 8 and the line 16 of narrowing ofthe gap between the pressed sheet and the back plate, an elongate horizontal expansion chamber 20. The top of the expansion chamber defined by the portion 8 of a plate 6 is performed with holes 43 along the longitudi nally central portion 49 thereofwhilstthe terminal portions 46, 48 are leftunpierced.

Towards edge 38, the sheet 4 is formed with a semi-circular bulge 32 directed away from the plate 6.

the diameter of the bulge diminishes over the portion 30 to a minimum at 28 and then increases in the portion 26 until the displacement of the sheet 4from the back plate 6 reaches a maximum at 12. From the margin 22 of the portion 12 of maximum displacement ofthe sheet4 from the plate 6, which defines a plenum chamber, the displacement diminishes sharply over area 14 and the sheet4 becomes contiguous with plate 6 at 24'. From the margin 24 ofthe area ofsharp incline to the edge24', sheet4is parallel and close to plate 6.

Where the sheet 4 is contiguous with the plate 6, the plates are welded together with weld spots 27. In an alternative construction, the sheet 4 and plate 6 are held together at the position of spots 27 by rivets or integrallyformed eyelets.

The burner element 1 is constructed essentially similarly to element 2 exceptthatthe back plate 3 and front sheet 9 are separate pieces of sheet steel. The back plate 3 is formed with a horizontal and slightly convex portion Sterminating in a flange 7 enclosed in gas-tight manner by a 1800 fold 25 offront sheet 9. The sheet9 is pressed toform a semi-circular portion 28, waisted at 29, the displacement of the sheet 9 from the plate3 reaching a maximum at23 and diminishing in an outwardly direction to line 17 before being displaced outwardly again at 19 to define an expansion chamber 21. The top ofthe expansion chamber 21, defined by portion 5 of plate 3 is, like the top ofthe chamber 20, perforated only along part of its length.

However,the portion 5 is perforated along its longitudinai extremities 35, 37 with holes 39 whilstthe intermediate portion is unpierced.

The sheet9 differs from the sheet 4 in that itforms at its lower extremity a 1800 fold 13 which not only secures itto the lower edge plate 3 but also includes the folded lower edge 41 of sheet 11 and so combines theburnerelements 1 and2togetheralongthe bottom edge44. Likewise, the sheet9wraps around the plate3 and the plate 6 and sheet 4 ofthe burner element2 along portions 42 and 40 of the shorter sides ofthe rectangle so as to aid the combination ofthe two burnerelements into a single unit.

As shown particularly in Fig. 4, the semi-circular bulges 32,33 together define a divided circular port 36 such as may be conveniently connected to a conven tonal gas supply pipe. Between the input port 36 and the narrowing of the semi-circular channels at 28 and 29, air inlet ports 34,31 are provided to allow induction of air into the gas stream.

Gas entering the port 36 from a supply pipe will be divided into two semi-circular channels defined by the respective back plates and the semi-circular bulges 32, 33 and entering into the plenum chambers defined between on the one hand the plate 6 and the sheet 4 and on the other between the plate 3 and the sheet 9 in the respective areas maximum displacement 12,23.

From these chambers the gas is able to pass through the necks 16, to enter entertheexpansion chambers 20 and 21 whence it passes out ofthe holes 43,39 which represent flame ports.

twill be observed from Fig. 3 that it is contemplated thatthe longitudinally innermost of the holes 39 and the longitudinal outermost ofthe holes 43 lie on the sametransverse line.As has already been mentioned the tops 8 and 5 ofthe expansion chambers are convexlycurved. If astro be expected the gas issues fromtheflameports normallytothe outer surface of the topps 8,5, it will be appreciated thatthe gas emitted from the holes 39 and 43 nearestto the centre line ofthe burner will in fact be directed overthe centre line. Inthecaseofthoseholessuch as 45,47 which lie in sametransverse line, the diversion of the gas streams overthe centre line will mean that the streams converge, and this convergance, as is well known,will provide a luminous effect which is very desirable.

Like the embodiment shown is Figs. 1 to 5, the burnershown in Figs. 6to 9 comprises two distinct burner elements 50,51, each comprising a substan tiallyflat back plate and a moulded front sheet, the elements being secured together back to back.

Unlike the first described embodiment, however, both of the elements ofthe second embodiment are formed from a single sheet of stainless steel, and the elements are secured together by welding together of the resective back plates at locations 52. Burner element 50 is an enantiomorph of element 51, so that the latter, which is shownn in Fig. 6, will be described in detail and it will be understood that element 50 is similar but of opposite hand.

The sheet of which the burner element is formed is essentially rectangular, and one longer edge 53 (part only shown) is located undertheturned-over rim 540f the opposed edge. The sheet is deformed along line 55 to create an outward bulge which is essentially semi-circularfrom 56to the lateral edge 57. The bulge diminishes only slightly between lines 58 and 59, defining there between the frontface 60 of a plenum chamber.

Upwardly of edge 59 the sheet curves backto the original plane before again bulgingoutwardlyto line 61 which defines the front surface of an elongate horizontal expansion chamber 62.

The sheet is bent backwardly at line 63 through a little short of 90", and is further turned at 64to define a substantially flat back plate which, together with the outward bulges of the front sheet defines the said plenum chamber and expansion chamber.

The top surface 65 between edges 63 and 64 is provided with longitudinal rows of holes 66 which, as clearlyshown in Fig. 7, are restricted to the central portion of the surface 65.

As firstformed, the lower edge ofthe back plate projects below the edge 53 ofthe front sheet, but during the pressing operation the projecting edge is folded overto provide the rim 54, already referred to, enclosing in a gas tight manner the edge 53. By appropriate tooling the entire shaping ofthe sheetto definethe burnerelement,completewithturnup rim 54 atthe bottom edge and similarturned over rims 67 and 68 atthe lateral edges, can be produced in a single, multi-stage, pass.

The pressing operation as described above defines the plenum chamber and the horizontal expansion chamber 62; It also defines a gas inlet passage of semi-circular section leading from the lateral edge at 57. As seen in Fig. 6the passage, considered in a direction from edge 57 to position 56 is of cylindrical form followed by a zone 69 of diminishing radius and a furtherzone70ofincreasing radius to provide a vents tri effect as well known in the art. Between the zone 69 and the edge 67 a slot in the sheet provides an air port71.

Between the plenum and expansion chambers the diminished bulge ofthe outer sh-eet defines with the back plate a narrow neck 72 for the restricted passage of gas. Thus gas entering the plenum chamber 60 via the aforementioned semi-circular passage, and admixed with airthrough the opening 71, passes through the neck 72 into the expansion chamber 62 and escapes through the holes 66 which in use define flame ports.

It has been saidthatthe element 50 is precisely similar to, though of opposite hand to, element51; there is, however, a further difference in that the upper surface of the corresponding expansion chamber is provided with longitudinal rows of holes, but whilst the holes 66 are concentrated towards the centre of the element 51 those provided in the element 50 are, as will be seen in Fig. 7, concentrated towards the extremities ofthat element As in the case of the first described embodiment, however,the innermost holes of element 50 and the outermost holes of element 51 lie in the same transverse line.

It has been said thatthe elements 51 and 50 are arranged and indeed secured together in a back-toback relationship. In order to cope with inadvertant departures ofthe respective back plates from absolute flatness, each ofthe back plates is provided with a number of rearward dimples in corresponding positions so that with the elements back to back and in registerthe dimples engage with one another so that there is a slight gap 73 between the back plates. In the embodiment illustrated, the gap is of constant width throughoutthe length and depth of the elements, but in an alternative embodiment, not shown, the gap may increase from top to bottom of the burner.

Indeed, by arranging for the respective elements to divergetowardstheirbottom edges, and by providing thatthetop edge 65 of the element 51 and the corresponding top edge of element 50 to be more nearly perpendicu larto the back plate, the streams of gas issuing from the respective rowsofflame ports can be arranged to converge at a distance above the elements, to a common plane.

A particularadvantageofthe burner described is that it can be manufactured by a very simple pressing operation. The operation can be even furthersimplified. By a suitable modification ofthe element 51, particularly in respect of the gas inlet, it should be possible to form a duplex burner comprising nottoo enantiomorphically distinguished elements but two elements of identical hand.

Claims (11)

1. An elongate gas burner having flame ports along its length, the ports being divided into at least two, independently supplied, groups separated from one anothertransverselyto the length direction ofthe burners.

2. A gas burner according to Claim 1 wherein the ports of one group are at least largely separated from those ofthe other group or groups lengthwise of the burner.

3. Agas burneraccording to Claim 2 wherein the groups overlap with one another.

4. A gas burner according to Claim 3 wherein at leastwherethe groups overlap the flame ports are mutally inclined to provide a flame effect.

5. An elongate burner having flame ports along its length comprising at leasttwo burner elements arranged side by side and each having at least one group of flame ports, the flame ports of one burner element being at least largely offset longitudinally relative to the flame ports of the or each other burner element..

6 Agas bu rner-amrding to Claim 5 Swherein each alemerat cornprises a substantially flat back plate.

7 Agas burner according to Claim 6wherein the back plates are inclined towards one another.

8. A gas burner according to any one of Claims 5-7 comprising two burner elements wherein, apart from the disposition ofthe flame ports, the elements are axact enantiomorphs of one another.

9. A gas burner according to anyone of Claims 5-7 comprising two burner elements wherein, apart from the disposition ofthe flame ports, the elements are exact duplicates of one another.

10. Agas burner according to any one of Claims 5 to 9 wherein each burner element is formed of a simple piece of sheet material.

11. An elongate gas burner having independently supplied longitudinally separated groups of gas ports, substantially as described with reference to Figs. 1 to 5 or Figs. to 9 of the accompanying drawings.