GB2309514A - Gas infra-red burner - Google Patents

Abstract

A gas burner (5) includes at least one mixing tube (4) mounted within a burner shell (13). Part of the surface of the burner shell (9) is formed from a perforated metal sheet (9) and a mesh screen (14). The mesh screen is formed from a series of different sized meshes, one of which is laid with the axis of its grid at 45{ to the longitudinal axis of the mixing tube (4). The mesh screen (14) forms a grid surface. The arrangement being such that a combustible gas fed via an end (10) of the mixing tube (4) is spread evenly under the mesh screen to be burnt as it filters through the mesh layers which glow to incandescence to produce infrared radiation which increases heat transfer. The burner (5) can be square, radial, circular, elliptical, oval, triangular or obround in cross section. The burner (5) can be incorporated under or around a cooking tank (1) in which foods are boiled, heated or fried.

Description

GAS INFRA-RED BURNER IN A HEATER TUBE OR HEAT EXCHANGER The present invention relates to burners and more particularly to a gas infrared burner for use in a heat exchange application such as in cooking equipment.

At present in commercial cooking equipment, foods are boiled, fried or heated in containers which are shaped to include a bath or tank in which the foodstuffs are placed while cooking. The baths are heated in a number of ways, for example, with an electric element or elements, and by gas burners which heat the surface of the bath in which the cooking liquid is retained.

In U.K. patent specification No. 2210965, the present applicant's described a gas burner which was an improvement on the known prior art. The gas burner included a distribution tube closed at one end and mounted within a shell. Part of the shell's surface is formed from a mesh screen. The mesh screen is formed from a series of different sized meshes. An injector feeds combustible gas through the distribution tube. The gas burns as it filters through the mesh screen. The mesh screen glows to incandescence to thereby produce infra-red radiation which increases heat transfer.

Technical difficulties were encountered and had to be overcome in adapting this development to quadrant style infra-red burners. A design solution was required which allowed for even heat distribution on the mesh screen while introducing the gas and 100% primary air into the burner throat.

It is an object of the present invention to improve on.the known prior art by attaining substantially even heat distribution on the surface associated with introducing the gas and air into a burner throat.

It is a further object of the present invention to improve the efficiency of a burner where its efficiency is based on kilograms of product produced per cubic metre volume heating gas used.

Yet a further object of the present invention is to increase the output of heat energy over a given combustion surface area.

Yet another object of the present invention is to provide the public with an alternative choice to a conventional heating system.

According to one aspect of the present invention there is provided a gas burner, wherein the burner includes at least one mixing tube mounted within a burner shell, part of the surface of the burner shell is formed from a perforated metal sheet and a mesh screen, the mesh screen being formed from a series of different sized meshes, one of which is laid with the axis of its grid at 450 to the longitudinal axis of the mixing tube, the mesh screen forms a grid surface, the arrangement being such that a combustible gas fed via an end of the mixing tube is spread evenly under the mesh screen to be burnt as it filters through the mesh layers which glow to incandescence to thereby produce infrared radiation which increases heat transfer.

The burner can be square, radial, circular, elliptical, oval, triangular or obround in cross section.

The burner can be incorporated under or around a cooking tank in which foods are boiled, heated or fried. However, it is to be app,re%,iated that the burner can be used in other cooking equipment. For example, the burner can be used under a bench top gas fryer, a flat steel griddle plate, glass for use as a cooking surface, or ceramic tiles for heating the sole of an oven chamber or direct or indirect heating of a chamber, or general space heating. More than one burner can be utilised in each unit.

The burner shell is constructed with a top woven mesh of a different metal alloy material to lower mesh(es) which are laid with its/their axis/axes parallel to the longitudinal axis of the burner and its associated mixing tube. A variation/s can extend to lower mesh(es) having their grid direction laid with its/ their axis/axes other than parallel to the longitudinal axis of the burner.

The mesh structure is essentially the same as that in U.K. patent specification No. 2210965. However, an additional inner mesh has been incorporated to provide support over an extended mesh area. The relationship of the burner to the tank wall and associated flueing is critical for the overall performance of the unit and was the subject of much experimentation and evaluation.

The gas burner can be incorporated into a tubular housing. The tubular housing can have at its output end a weir plate positioned to retain in an upper region of the tubular housing heat and exhaust gases from the gas burner to thereby improve heat transfer to the tubular housing.

The tubular housing can be square, round, elliptical, oval, triangular or obround in section.

Further aspects of the invention will become apparent from the following description which is given by way of example with reference to, the accompanying drawings in which: Figure 1 shows a perspective view of the rear of a fryer tank incorporating three tubular housings according to the invention; Figure 2 shows an example of a weir plate mounted relative to one of the tubular housings shown in Figure 1; Figure 3 shows a side view partly sectioned of a burner according to the invention; Figure 4 shows a view across the section B-B in Figure 3; Figure 5 shows a side view of the burner as shown in Figure 3; Figure 6 shows a sectional view of a mesh screen before it is formed into an arc; Figure 7 shows a front view of a single pan cooking tank in which two of the burners have been implemented; and Figure 8 shows a front view of a twin pan versions of cooking tank.

Figures 1 and 2 show part of a fryer tank 1 and this consists of a stainless steel housing one end 2 of which has a flue outlet 3 (Figure 2) connected thereto. The tank 1 has three similar exchanger tubes 4 each of which has a burner 5 the general position of which is shown. The outlet end 6 of each tube 4 has a weir plate 7. The weir plate 7 of each tube 4 can be discrete, or as shown in Figure 1 an elongate plate 7 can be utilised.

Preferably, each tube 4 has a weir plate 7. The weir plates 7 can be mounted as shown in Figure 2 spaced from the end 6 of each tube 4; and, preferably, the edge 8 of weir plate or plates 7 extends to a point near to the centre of the tubes 4.

Alternatively as shown in Figure 2, the weir plate 7 can have a return 1 8 on its lower edge. The return 18 extends into the heat exchanger tube 4 to thereby trap further heat (see Figure 2).

Alternatively, the weir plate(s) 7, can be inset into the end of each heat exchanger tube 4. In order to improve heat exchange efficiency, the inner surface of each tube 4 can be coated with a surface coating such as manganese dioxide or other suitable compound which will form a matt black coating.

The heat exchanger tubes 4 each have their own burner 5. Each burner 5 has a burner shell 9 which consists of a semi-cylindrical member 13 the upper portion 14 of which is formed of a plurality of mesh layers. In the preferred embodiment, the portion 14 is formed from a series of differently-sized, differently-oriented meshes. Preferably, there are at least three mesh layers in the composite structure.

Underneath the mesh layers 14 (i.e. between the burner and the mesh layers) is a baffle 9. The baffle 9 is a perforated curved metal sheet. Gas diffuses through the mesh layers 14 and the baffle 9 and is burnt efficiently.

The mesh 14 glows on the surface layer during the burning of the gas to produce infra-red radiation which is absorbed by the to-be-heated surface. The heat is more evenly dispersed over a wide surface area of the mesh layers 1 4 than from an equivalent rated blue flame gas burner in a comparable use. This even heat distribution from the burner relates directly to more even heat absorption over a given area.

In use, gas flows from the interior into a mixer tube intake 10 to be fed along with the combustion air through a mixer tube 11 to be distributed from elongate holes or ports 12 in housing 1 3 to flow evenly through the baffle 9 and mesh 14 (Figure 3) of the burner shell. The gas burns incandescently thereby creating infra-red radiation along the full area of the mesh. The infra-red radiation is absorbed by the surface to be heated. The heat energy rises to be trapped by the weir plate 7 against the surface of the tube 4 by the weir plate 7 when in tube application.

The new deep fat fryer has as its main design criteria efficiency based on kilograms of product per cubic metre of gas consumed and high output based on kilograms of product produced in a time period.

The burner has been described with reference to a fryer. However, it is to be appreciated that the burner can be used in other cooking equipment or heating application. For example, the burner can be used under a bench top fryer, a flat steel griddle plate, glass for use as a cooking surface, or ceramic tiles for heating the sole of an oven chamber or direct or indirect heating of a chamber, or general space heating. More than one burner can be used.

It will thus be seen that the present invention provides a gas infrared burner in a heater tube or heat exchanger.

Where in the aforegoing description, reference has been made to integers or components having known equivalents, then such equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example and with reference to possible embodiments thereof, it is to be appreciated that improvements and/or modifications may be made thereto without departing from the scope or spirit of the attached claims.

Claims (11)

1. A gas burner, wherein the burner includes at least one mixing tube mounted within a burner shell, part of the surface of the burner shell is formed from a perforated metal sheet and a mesh screen, the mesh screen being formed from a series of different sized meshes, one of which is laid with the axis of its grid at 450 to the longitudinal axis of the mixing tube, the mesh screen forms a grid surface, the arrangement being such that a combustible gas fed via an end of the mixing tube is spread evenly under the mesh screen to be burnt as it filters through the mesh layers which glow to incandescence to thereby produce infrared radiation which increases heat transfer.

2. A gas burner as claimed in claim 1 wherein the burner shell is square, radial, circular, elliptical, oval, triangular or obround in cross section.

3. A gas burner as claimed in claim 1 or claim 2 wherein the burner shell is constructed with a top woven mesh of a different metal alloy material to lower mesh(es) which are laid with its/their axis/axes parallel to the longitudinal axis of the burner and its associated mixing tube.

4. A gas burner as claimed in claim 3 wherein the lower mesh(es) have their grid direction laid with its/their axis/axes other than parallel to the longitudinal axis of the burner shell.

5. A gas burner as claimed in any one of the preceding claim wherein the burner shell is incorporated into a tubular housing, the tubular housing having at its output end a weir plate positioned to retain in an upper region of the tubular housing heat and exhaust gases from the gas burner to thereby improve heat transfer to the tubular housing.

6. A gas burner as claimed in claim 5 wherein the tubular housing is square, round, elliptical, oval, triangular or obround in section.

7. A gas burner as claimed in claim 1 and substantially as hereinbefore described with reference to Figures 3 to 6 of the accompanying drawings.

8. A cooker incorporating one or more gas burners as claimed in any one of the preceding claims.

9. A cooker as claimed in claim 8 wherein the burner is incorporated under or around a cooking tank in which foods are boiled, heated or fried.

10. A cooker as claimed in claim 8 or claim 9 wherein the burner is used under a bench top gas fryer, a flat steel griddle plate, glass for use as a cooking surface, or ceramic tiles for heating the sole of an oven chamber or direct or indirect heating of a chamber, or general space heating.

11. A cooker as claimed in claim 8 and substantially as herein described with reference to the accompanying drawings.