EP0384643A1

EP0384643A1 - Solid fuel effect gas fire

Info

Publication number: EP0384643A1
Application number: EP90301609A
Authority: EP
Inventors: Michael C. C/O Taylor & Portway Portway
Original assignee: Taylor & Portway
Current assignee: Taylor & Portway
Priority date: 1989-02-20
Filing date: 1990-02-15
Publication date: 1990-08-29
Also published as: GB8903831D0

Abstract

A solid fuel effect gas fire comprising at least one burner adapted for attachment to a gas supply, and being adapted to provide a primary and secondary air supply, support means to support refractory bodies in the form of artificial coals or coke or other similar smokeless fuels or logs above the or each burner, said support means being spaced from said burner so that in use the gas is completely burnt by the primary and secondary air in the space between the burner and the refractory bodies.

Description

The present invention relates to a solid fuel effect gas fire. Such fires have become popular in recent years, and generally comprise a gas fire which can be mounted in an existing fireplace, artificial solid fuel being provided in the form of refractory bodies, and gas burners being mounted below the refractory bodies. Most of these gas fires are arranged so as to simulate as closely as possible the flames of a normal coal fire or log fire and many arrangements have been proposed to provide the necessary flames apparently coming from the coals or logs. To simulate this effect, the solid fuel effect gas fires have usually been arranged so as to complete the combustion of the gas in a position adjacent the refractory bodies so that flames extend over the refractory bodies.
The present invention provides a solid fuel effect gas fire comprising at least one burner adapted for attachment to a gas source, and being adapted to provide a primary air supply, means to support refractory bodies in the form of artificial coals or coke or other similar smokeless fuels or logs above the or each burner, said support means being spaced from said burner so that in use the gas is completely burnt by the primary air and by secondary air in the space between the burner and the refractory bodies. Thus, in this case, complete combustion of the gas takes place below the refractory bodies so as to produce the effect of a coke or like smokeless fuel fire, in which the coke or like smokeless fuel glows, but does not produce flames in any quantity.
Such an arrangement of a gas fire is particularly efficient, as the gas burns efficiently, unlike in many other solid fuel effect gas fires, the refractory bodies being heated by the hot gas above the gas flame.
To further improve the efficiency, there may be provided, as is known, a heat exchanger around the outside of the gas fire, the heat exchanger comprising plates forming the back and/or the sides of the gas fire, behind which is provided an air passage through which air may pass and be heated by the back and/or side plates.
A preferred embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings in which:

Figure 1 is a front view of a solid fuel effect gas fire comprising the first embodiment of the invention,
Figure 2 is section on the line 2-2 of the gas fire of Figure 1,
Figure 3 is a detail of a front view of part of the gas fire of Figure 1,
Figure 4 is a perspective view of an alternative arrangement of part of the fire of Figure 1,
Figure 5 is a plan view of the overall shape of the gas fire of Figure 1,
Figure 6 is a front view of a solid fuel effect gas fire comprising a second embodiment of the invention, and,
Figure 7 is a section on the line 7-7 of Figure 6, but also including a front decorative panel.

Referring to Figure 1 there is shown a front view of a solid fuel effect gas fire 10 especially adapted to fit into an existing fireplace. The horizontal sectional shape is illustrated in Figure 5, 11 indicating the front face, 12 the rear face and 13 and 14 the side faces. The side faces 13, 14 are provided by side plates 16,17 and the rear face 12 is provided by a rear plate 18 (see Figure 2). Extending generally from side to side are two burners 21,22 of generally standard design. Each burner comprises a long hollow rectangular box, having ports 23 in its upper surface, and, at one end 24, a gas inlet 25 connected to a gas jet 26 surrounded by a primary air inlet 25 connected to a gas jet 26 surrounded by a primary air inlet 27. The burners each preferably include a stainless steel top surface which includes single or multiple ports. The ports are designed so that the gas entrains sufficient secondary air to give good combustion with a sharp blue flame down its entire length. This flame is very hot. Mounted above the burners 21,22 is a support means 28 for supporting thereabove loose refractory bodies preferably in the form of separate artificial coke pieces 29. Such refractory bodies are well known and typically may comprise artificial logs, artificial coals, or artificial coke pieces.
The lower layers of artificial coke pieces 29 may be made of hard "slip cast" ceramic, and lighter weight ceramic fibre coke pieces can be used thereabove to build the fire to the desired shape and size.
The support means 28 which is made of hard ceramic material which is heat resistant, extends between lugs 31,32 provided on the side plates 16,17 and comprises a front, centre and rear support beams 33,34,35 which extend substantially from side to side and are spaced from one another. The front, centre and rear support beams 33,34,35 are mounted on a flat tray 36 which includes cutouts corresponding to the spacing between the front and centre support beams 33,34 and the centre and rear support beams 34,35. The front and rear support beams 33,35 include at spaced intervals holes 37 therethrough and the centre support beam 34 includes semi circular slots 38 aligning with the holes 37 so that a plurality of horizontally disposed rods 39 may be mounted between respective holes 37 in the front and rear support beams 33,35, being supported in the middle by a respective slot 38 of the centre support beam 34. In this way a grating 41 of rods is produced which can support the artificial coke pieces 29. A spacer block 42 of inert material may be provided between the rear of the rear support means 35 and the rear plate 18. The front, centre and rear support beams 33,34,35, the tray 36 and the rods 39 as well as the spacer block 42 may be made of refractory material and in particular, a moulded hard ceramic material is preferred. The tray 36 may alternatively be made of stainless steel protected by heat insulating material.
As will be noted from Figure 2, the burners 21,22 are situated so that their ports 23 extend into spaces 43,44 between respectively the front and centre support means 33,34, and the centre and rear support beams 34,35. These spaces 43,44 thus extend between the ports 23 and the grid 41 formed by the rods 39.
In use the distance "D" between the burners 21,22 and lowermost refractory bodies supported on the grid 41 is preferably approximately 30mm but normally, a range of distances from 22mm to 30mm will be sufficient (although it may, of course, be longer). These dimensions are suitable for natural gas (as supplied through the gas mains in the UK at 15-20 mbar) or liquid petroleum gas (bottled gas) at, typically 37 mbar.
It will be noted that the upper surface of each burner 21,22 is spaced a short distance below the support means 28 whereby secondary air may flow across the upper surface of the burners 21,22 to allow full combustion of the gas/air mixture passing out of the ports 23.
In use, the front of the gas fire 10 mounts a suitable decorative closure member (not shown in Figures 1 to 5).
In operation, the gas fire shown in Figures 1 to 5 operates as follows:
Gas is provided from gas inlet 25 through the gas jet 26, and is mixed with primary air in the primary air inlet 27, so that within each burner 21,22 there is provided a mixture of gas and primary air. This gas mixture passes up through the ports 23 where it mixes with secondary air passing through the space between the relevant burner 21,22 and the underside of the support means 28. The gas/air mixture mixes with the secondary air and burns to provide relatively small flames indicated at 46,47 which, as can be seen, do not extend up as far as the grid 41. Indeed, the distance between the burners 21,22 and the grid 41 is set so that, for a particular type of gas and pressure, all of the gas is burnt by primary and secondary air before reaching the grid 41. Thus, all of the gas has been burnt before reaching the grid 41 and in this way the gas can be burnt with the maximum efficiency to provide the maximum amount of heat.
The hot combusted gas then passes up over the artificial coke pieces 29. As already referred to, the first two or three layers of artificial coke pieces 29 are of hard ceramic material and because of the considerable heat produced by the burners, these first few layers are heated to bright red (hence the reason for using hard ceramic), the less dense coke pieces above then being heated to a lesser extent and glowing a duller red. These are made of lightweight refractory material and rapidly heat up to glow red hot like a coke fire. As they glow red hot they radiate heat similar to the manner of a coke fire. Of course, the support beams 33,34,35 and rods 39 will glow red to add to the effect.
In an alternative arrangement, the front, centre and rear support beams 33,34,35 may be replaced by a frame of the form shown in Figure 4. In this case, there are front, centre and rear connected beams 48-50, the beams 48-50 being connected by end pieces 51,52. In this case, all of the beams incorporate slots generally similar to the slots 38 of the earlier embodiment, except that the slots in the front and rear beams 48,50 have closed ends. The rods 39 may simply drop into three aligned slots.
In an alternative arrangement referred to as a heat exchanger, the side and rear plates 16-18 are double skinned, having an air supply to the lower end of the generally closed space formed therein, and having means to pass the warm air which passes up between the two skins of the double skinned plates out into the room, normally via a slot above the gas fire.
The invention is not restricted to the details of the foregoing examples. For example, if a particular fireplace is particularly deep then there may be provided at least two centre beams 34, and at least three burners spaced one behind another.
Furthermore, the spacing of the burners and the support beams is relatively important. For example, because the burners do not extend into the spaces between the support beams, they are not subjected to a great deal of reflected heat which increases their life.
Whilst the description so far has referred to the gas jets working at high efficiency so that there are no or few flames visible, it is possible if desired to have a secondary burner working on neat gas at the rear of the gas fire to give "white" flames if so desired.
By using oversized jets in the burner it is possible to achieve small blue gas flames over the coke face.
In the second embodiment shown in Figures 6 and 7 similar parts carry the same reference numerals. Thus the outer casing of the gas fire is substantially the same as before, Figure 7, however showing in this case a decorative front panel 56.
Only one burner 21 is provided and this is angled rearwardly as shown in the cross section of Figure 7. Only the front 33 and rear 35 support beams are provided, the single burner 21 being arranged to direct its flame up between the front and rear support beams 33,35 into the space illustrated in Figure 7. The rear support beam 35 includes two shoulders 57, 58, the lower, 57, being horizontally aligned with the top surface 59 of the front support beam 33.
In this case, the support means 28 comprises a number of generally half round tubular sections 61 made of hard ceramic material of a diameter comparable with the dimensions of the coke pieces 29. The exact cross section is not particularly important and so other shapes, eg. semi-elliptical sections may be provided. The front edge of the semi-cylindrical tubular sections 61 may be cut at an angle rearwardly as is clear from Figure 7 so as to generally match the sloping surface of the top of the mound of artificial coke pieces 29. The lower layer 62 of these tubular sections 61 extend across the gas fire from generally the side 13 to 14, and in the illustrated example are provided by three semi-cylindrical tubular sections 61. The lower edges of the semi-cylindrical tubular sections rest on the top surface 59 and lower shoulder 57 as is clear from Figures 6 and 7. Above this lower layer of semi-cylindrical tubular section 61 is provided an upper layer 63 which in this case comprises two semi-cylindrical tubular sections 61 which are arranged between the sections 61 of the lower layer 62 in the configuration shown in Figure 6.
The artificial coke pieces 29 may then be disposed between and above the semi-cylindrical tubular sections 61.
The front edge of the semi-cylindrical tubular sections 61 may be cut at an angle rearwardly as is clear from Figure 7 so as to generally match the sloping surface of the top of the mound of artificial coke pieces 29.
In the arrangement shown in Figure 6 and 7, the artificial coke pieces 29 forming the front line of coke pieces should be of hard ceramic material as they would be subject to greater heat but the artificial coke pieces towards the top of the fire may be of softer fibre ceramic coals which are cheaper as they are not heated to such an extent.
In something of a combination of the arrangements of Figures 1 and 2, and Figures 6 and 7, the semi-cylindrical tubular section 62 may be fitted in place of the rods 39 and in the particular preferred arrangement, the width of the sections 61 may be such that their edges may fit into the slot 38.

Claims

1. A solid fuel effect gas fire comprising at least one burner (21,22) adapted for attachment to a gas supply (25), and being adapted to provide a primary (27) air supply, support means (28) to support refractory bodies (29) in the form of artificial coals or coke or other similar smokeless fuels or logs above the or each burner, said support means (28) being spaced from said burner (21,22) so that in use the gas is completely burnt by the primary air and secondary air in the space (43,44) between the burner (21,22) and the refractory bodies (29).

2. A solid fuel effect gas fire as claimed in claim 1 characterised in that the burner (21,22) is spaced from said support means (28) by at least 25mm.

3. As solid fuel effect gas fire as claimed in 1 or 2 characterised in that said burner (21,22) is spaced from said support means (28) by a distance in the range 25mm to 30mm.

4. A solid fuel effect gas fire as claimed in any of claims 1 to 3 characterised in that said support means (28) comprises a plurality of spaced horizontally disposed rods (39).

5. A solid fuel effect gas fire as claimed in any of claims 1 to 3 characterised in that said support means (28) comprises a plurality of hollow members (61).

6. A solid fuel effect gas fire as claimed in claim 5 characterised in that said hollow members (61) comprise a plurality of semi-cylindrical tube members (61).

7. A solid fuel effect gas fire as claimed in any of claims 1 to 6 characterised in that said at least one burner (21,22) extends substantially between opposite sides of said gas fire.

8. A solid fuel effect gas fire as claimed in any of claims 1 to 7 characterised in that said at least one burner (21,22) includes a gas jet (26) and primary air inlet (27) arranged so that gas fed to said gas jet (26) is mixed with primary air from the primary air inlet (27).

9. A solid fuel effect gas fire as claimed in any of claims 1 to 8 characterised in that said at least one burner (21,22) includes ports (23) in a upper surface thereof whereby gas mixed with primary air passes through said ports (23) to mix with secondary air.

10. A solid fuel effect gas fire as claimed in any of claims 1 to 9 characterised by a heat exchanger provided at the rear and/or sides of said gas fire, said heat exchanger comprising plates forming the back and/or the sides of the gas fire, behind which is provided an air passage through which air made paths and be heated by the back/or side plates.