GB2208704A - Simulated solid fuel gas fires - Google Patents

Abstract

A solid fuel effect gas fire is provided with one or more air entry holes 22 in a back plate 13. <IMAGE>

Description

TITLE: SOLID FUEL EFFECT GAS FIRE This invention relates to heating apparatus which burn gaseous fuel in a way that is intended to simulate the combustion of solid fuel.

In known apparatus there is provided an opentopped tray containing a mass of particulate noncombustible material which serves as a bed to distribute the gas to be burnt across the greater area of the container. A plurality of refractory bodies, shaped and coloured to simulate solid-fuel, are mounted on the top of the mass of particulate refractory material and means are provided for introducing fuel gas into the mass of particulate material so that it percolates through the material into spaces between the bodies where, in use, at least some of the fuel gas burns in said spaces with a luminous flame when fed with neat gas. Primary aeration produces a nonluminous flame.

Such known apparatus are constructed so that the gas supply is either pre-aerated, that is air is mixed with gas before the combustion process occurs or may be designed to burn raw gas.

(An example of a gas fire of the kind described above is disclosed in British Patent Specification No.

1541423).

It is recognised that the method of primary or pre-aeration produces a more efficient combustion system with a low carbon monoxide to carbon dioxide ratio. However the flame produced is not appealing, being short and tinged with blue colour. Furthermore fires of this type often consist of a hot centre into which any peripheral flames are pulled in a similar way in which objects are sucked into a fire storm. The burning of raw gas, however, produces a visually satisfactory luminous flame but it is inefficient, with a high carbon monoxide to carbon dioxide ratio and also produces soot being mainly composed of unburned and partially oxidised products of carbon.

In pre-aerated gas fires gas (town gas, natural gas or liquified petroleum gas such as propane or butane) is injected into the opening of a venturi. The air/gas mixture is then dispersed through the fire bed.

Combustion takes place on the surface of the fire bed when the air/gas mixture burns in the presence of air drawn in from around the sides of the burner tray. The refractory bodies (normally shaped to resemble logs or coals) become very hot. The hot products of combustion rise quickly through the heart of the refractory bodies causing a partial vacuum sucking in increasing volumes of secondary air from around the periphery of the burner tray. This causes most of the peripheral flame to be drawn nearly horizonatally towards the heart of the fire. These peripheral flames are blue in colour due to the excessive amount of air and look unrealistic because of their horizontal direction.

It is an object of the invention to provide a solid-fuel effect fire which in use has a mixture of luminous and non-luminous flames producing a flame pattern more closely simulating the flames of a solid fuel burning appliance.

According to the present invention there is provided a solid-fuel effect gas fire comprising a mass of particulate refractory material in an open-topped tray, a back plate extending upwardly at the rear of the tray, a plurality of refractory bodies shaped and coloured to simulate solid fuel supported by said mass of refractory material and by said back plate, and means for introducing fuel gas into the mass of particulate material and thereafter through the interstices between the refractory bodies, said back plate having at least one aperture which, when the fire is in use, permits entry of air into the region of the refractory bodies thereby to reduce the partial vacuum produced by the rising of burnt gas.

The invention will now be described by way of example with reference to the accompanying drawing which is a sectional view taken centrally of the fire from front to rear.

The solid-fuel effect fire comprises an open topped tray 10, which may be trapezoidal in plan view, standing on legs 11 provided at the four corners thereof. The rear of the tray is provided with a back plate 13 set at an angle of about 600 to the horizontal.

The back plate 13 may be formed integrally with the tray as shown or separately attached by fixtures.

A refractory lining 14 is provided against the back plate.

Mounted in an aperture at the centre of the base of the tray is a venturi 15 the upper end of which is surrounded by a gas distribution cap 16 supported on legs 17 above the base of the tray. The lower end of the venturi 15 protrudes beneath the tray and receives gas from a nozzle 18.

A mass of particulate refractory material 20 is supported by the tray and the lower end of the refractory lining 14. The mass 20 and the back plate 13 together support a plurality of refractory bodies 21 shaped and coloured to simulate solid fuel.

The back plate 13 and the refractory lining 14 are provided with aligned apertures 22, 23 to form a single air entry aperture.

If required other air entry apertures may be formed in the back plate provided that air is not permitted in too large a quantity as this may cause excessive cooling.

The essential feature of the invention is to introduce air into the rear of the fire to reduce the partial vacuum caused. Furthermore the additional air causes a source of localised luminous flame. Air may be introduced in a controlled manner in one or more of the sides in addition to the rear.

The back plate extends from the fire bed either vertically, horizontally or at an angle as shown. The additional air drawn into the fire bed results in four benefits: 1. It breaks the partial vacuum and allows the flames to permeate vertically and evenly throughout the majority of the fire bed.

2. It causes the whole fire bed and in particular the majority of the surface elements to become hot.

3. It stops the blue flame created by excess air, and replaces it with a luminous flame produced by the quenching process of air drawn in through the hole on some parts of the fire bed.

14. It produces some localised luminous flame in a general background of non-luminous flame.

Non-aerated gas may be introduced into the fire bed. The effect in this case is to produce a pleasing pattern of some limited non-luminous flame around the air holes in a background of luminous flame. The efficiency of the fire is increased and the ratio of carbon monoxide to carbon dioxide is reduced.

Claims (5)

1. A solid fuel effect gas fire comprising a mass of particulate refractory material in an open-topped tray, a back plate extending upwardly at the rear of the tray, a plurality of refractory bodies shaped and coloured to simulate solid fuel supported by said mass of refractory material and by said back plate, and means for introducing fuel gas into the mass of particulate material and thereafter through the interstices between the refractory bodies, said back plate having at least one aperture which, when the fire is in use, permits entry of air into the region of the refractory bodies thereby to reduce the partial vacuum produced by the rising of burnt gas.

2. A solid fuel effect gas fire as claimed in.

Claim 1 wherein gas is introduced through a venturi that passes through the tray and is covered by a gas distribution cap supported on legs above the base of the tray.

3. A solid fuel effect gas fire as claimed in Claim 1 wherein a refractory lining is provided against the back plate and the aperture or each aperture extends through the back plate and lining.

4. A solid fuel effect gas fire as claimed in Claim 1 which is arranged so that non aerated gas is introduced into the fire.

5. A solid fuel effect gas fire substantially as described with reference to the accompanying drawing.