EP3513122B1

EP3513122B1 - Premix gas burner

Info

Publication number: EP3513122B1
Application number: EP17742700.2A
Authority: EP
Inventors: Dinand Lamberts; Roelof BOER; Daniel HOLTROP
Original assignee: Bekaert Combustion Technology BV
Current assignee: Bekaert Combustion Technology BV
Priority date: 2016-09-13
Filing date: 2017-07-13
Publication date: 2020-12-16
Anticipated expiration: 2037-07-13
Also published as: JP2019526776A; CN112050208A; WO2018050578A1; EP3513123B1; KR102368554B1; CN109716023B; CN109690190B; KR20190045211A; JP2019526777A; CN109690190A; CN109716023A; EP3513123A1; EP3513122A1; WO2018050310A1

Description

Technical Field

The invention relates to the field of premix gas burners, more particularly to surface stabilized premix gas burners comprising a woven wire mesh as burner deck.

Background Art

Surface stabilized premix gas burner having a woven wire mesh burner deck are known.
US5474443A discloses a premix gas burner with a hemispherical burner deck out of a woven wire mesh.
US2005/172915 shows a premix gas burner having a woven wire mesh combustion surface comprising rigidizing ribs.
US2014/0011143A1 discloses a premix gas burner comprising a metal mounting plate, a burner deck and a distributor. The metal mounting plate has a plane section. The burner deck comprises a mesh made of metal or ceramic fibers or a compact material having openings or a porous material. The distributor comprises a sheet provided with openings or a metal mesh or a porous metal. The metal mounting plate comprises an opening. The burner deck is inserted through the opening of the metal mounting plate. The burner deck is bent such that a flange parallel with the plane section of the metal mounting plate is provided.
US3,857,670 discloses a radiant burner having a hollow body with a closed rear and a peripheral wall extending forwardly from the rear to define an open ended chamber. There is an outwardly extending, planar spacing flange on the front end of the peripheral wall. A perforated diffuser plate extends across the chamber in a plane located rearwardly from the end of the wall. The plate has a forwardly directed flange around its perimeter and an outwardly extending marginal edge which lies against the spacing flange. A primary screen consisting of a plurality of layers of fine bias cut mesh extends across the open end of the chamber with its edges overlying and adjacent to the front surface of the edge of the plate. A reverberator grid which has a planar body and a backwardly extending border flange is located in front of the primary screen with an outwardly extending edge of its flange adjacent the surface of the edge of the primary screen and its main body spaced forwardly from the primary screen by its flange. The layers of the primary screen and the reverberator grid are spot welded together at certain points. The central portion of the primary screen is dished forwardly toward the reverberator grid. Retaining lips on the spacing flange of the body are folded over inwardly against the front surface of the edge of the reverberator grid flange for retaining the diffuser plate and the primary screen and reverberator grid in place in the burner. The retaining lips are bent over to relatively tightly compress the edges of the diffuser plate, primary screen and reverberator grid against each other, but not tightly enough to prevent expansion of these elements when the burner is operating. There is an inlet for combustible gases into the chamber behind the diffuser plate.

Disclosure of Invention

The first aspect of the invention is a premix gas burner comprising a metal mounting plate, a burner deck and a metal plate structure. The metal mounting plate has a plane section for mounting the burner in a heating appliance. The burner deck comprises - and preferably consists out of - a woven wire mesh onto which the flames are stabilized when the burner is in use. At least part of the metal plate structure is perforated for the premix gas to flow through the perforations before the premix gas flows through the woven wire mesh. This way, the metal plate structure acts as a distributor for the premix gas. The metal mounting plate comprises an opening. The woven wire mesh is inserted through the opening of the metal mounting plate. The woven wire mesh is bent, such that a flange parallel with the plane section of the metal mounting plate is provided. The circumference of the burner deck has the shape of a rectangle of which the two short sides have - preferably continuously - been rounded. The flange is held between the metal mounting plate and the metal plate structure such that play of the flange relative to the metal mounting plate and relative to the metal plate structure is present. No flange is provided along the - preferably continuously - rounded short sides.
The woven wire mesh burner deck of surface stabilized premix gas burners gets hot when the burner is in use. The woven wire mesh burner deck needs to be able to cope with the stresses induced by the thermal expansion associated with the high temperature when the burner is in use and by the shrinkage when the burner is not in use. If this is not the case, early mechanical failure or irregular permanent deformation of the burner deck will occur. Thanks to the provision of play of the flange between the metal mounting plate and the metal plate structure, a certain amount of movement of the woven wire mesh relative to the metal mounting plate and to the metal plate structure is possible when the woven wire mesh expands when warming up or shrinks when cooling down. Therefore surprisingly, the premix gas burner of the invention has shown to be very well suited to withstand thermal expansion and shrinkage, resulting in a long lifetime of the premix gas burner.
The woven wire mesh is bent, such that a flange parallel with the plane section of the metal mounting plate is provided. The flange is held between the metal mounting plate and the metal plate structure such that play of the flange relative to the metal mounting plate and relative to the metal plate structure is present. Because of the bent of the woven wire mesh forming the flange, the play is such that the flange can move at thermal expansion and contraction, however, the burner deck cannot "escape" from in between the metal mounting plate and the metal plate structure.
Preferably, the woven wire mesh has a thickness between 0.6 and 1.3 mm. As an example, a woven wire mesh of 0.9 mm thickness can advantageously be used in the invention.
Preferably, the play being present of the flange relative to the metal mounting plate and relative to the metal plate structure is at least 0.4 mm. More preferably, the play is between 0.4 and 1.5 mm; even more preferably, the play is less than 1.3 mm. With the play is meant the distance between the metal mounting plate and the metal plate structure from which the thickness of the woven wire mesh is subtracted.
Preferably, the flange has in cold condition a longitudinal play of at least 0.3 mm. The longitudinal play is the play in the direction of the plane of the flange.
In a preferred embodiment, the flange is along the circumference of the woven wire mesh split in a plurality of flange segments. It is meant that along the circumference of the woven wire mesh, the flange is split in segments.
In a preferred embodiment, the burner deck is provided in a convex shape. It is meant that when the burner is in operation, the flames of the burner are anchored onto the convex side of the burner deck. More preferably, the full surface of the burner deck is provided in a convex shape; meant is that when the burner is in operation, the full surface of the burner deck at the side of which the flames are anchored has a convex shape.
According to the invention, no flange is provided along the - preferably continuously - rounded short sides. Such burners are even better suited for long lifetime use, as the absence of a flange along the short sides allows better thermal expansion of the woven wire mesh in its length direction. Furthermore, such burner can be manufactured more easily.
Preferably, all zones of the metal plate structure provided with perforations are provided at a distance from the woven wire mesh. It is meant that no perforation makes contact with the woven wire mesh, but that the perforation is positioned at a distance from the woven wire mesh.
In a preferred embodiment, all zones of the metal plate structure provided with perforations are in contact with the woven wire mesh.
In a preferred embodiment, the full surface of the burner deck onto which flames are stabilized when the burner is in use, is provided by the woven wire mesh.
In a preferred embodiment, the metal mounting plate comprises a first section and the metal plate structure comprises a first section. The first section of the metal mounting plate is parallel with and in contact with the first section of the metal plate structure. The first section of the metal mounting plate is welded onto the first section of the metal plate structure, e.g. by means of spot welds or by means of another welding technique. More preferably, the flange of the woven wire mesh is parallel with the first section of the metal mounting plate and with the first section of the metal plate structure. More preferably, the first section of the metal mounting plate and the first section of the metal plate structure surround the full circumference of the woven wire mesh.
In a preferred embodiment, the metal mounting plate comprises an upstanding ridge at the opening through which the woven wire mesh is inserted through the metal mounting plate. Preferably, the upstanding ridge is oriented in the direction opposite to the flange of the woven wire mesh. More preferably, the upstanding ridge is at least over part of its surface in contact with the woven wire mesh.
Preferably, in the woven wire mesh the bent angle providing the flange of the woven wire mesh is at least 90°.
In a preferred embodiment, the woven wire mesh does not comprise ribs nor embossments.
In a preferred embodiment, the woven wire mesh comprises ribs and/or embossments.
Preferably, the burner deck has a double curved surface. Where a surface is at a point on it double curved, there is at that point no direction in which the radius of curvature is infinite. As an example, a cylindrical burner is a burner that has a single curved surface, not a double curved surface.
The second aspect of the invention is a condensing boiler comprising a premix gas burner as in any embodiment of the first aspect of the invention. Preferably, the condensing boiler comprises a cast aluminium heat exchanger.

Brief Description of Figures in the Drawings

Figures 1, 2, 3 and 4 show views of a burner according to the invention.
Figures 4 and 5 show cross sections of a burner according to the invention.

Mode(s) for Carrying Out the Invention

Figure 1 shows a view 100 onto the burner deck of a burner according to the invention. Figure 2 shows a side view 200 of a burner according to the invention. Figure 3 shows a bottom view 300 of a burner according to the invention. Figure 4 shows a view on a cross section 400 taken perpendicularly to the long sides of the rectangular circumference with rounded short sides of the burner deck of the burner according to the invention.
The premix gas burner of figures 1 - 4 comprises a metal mounting plate 102, a burner deck 104 and a metal plate structure 106. The metal mounting plate has a plane section 103 for mounting the burner in a heating appliance, e.g. in a boiler. The burner deck consists out of a woven wire mesh onto which the flames are stabilized when the burner is in use. The burner deck has a convex shape over its full surface. The circumference of the burner deck has the shape of a rectangle of which the two short sides have been continuously rounded.
Part of the metal plate structure is perforated for the premix gas to flow through the perforations 108 before the premix gas flows through the woven wire mesh. This way, the metal plate structure acts as a distributor for the premix gas. The metal mounting plate has an opening. All zones of the metal plate structure provided with perforations are provided at a distance of at least 1 mm from the woven wire mesh. The woven wire mesh is inserted through the opening of the metal mounting plate.
The woven wire mesh is bent, such that a flange 110 parallel with the plane section of the metal mounting plate is provided.. The bent angle α is more than 90°. The flange 110 is held between the metal mounting plate and the metal plate structure such that play of the flange relative to the metal mounting plate and relative to the metal plate structure is present.
In the example, the woven wire mesh 104 is 0.9 mm thick. The play - which is the distance between the metal mounting plate and the metal plate structure from which the thickness of the woven wire mesh is subtracted - is 1.1 mm. In cold condition, the flange has a longitudinal play of 0.5 mm; the longitudinal play is the play in the direction of the plane of the flange.
The metal mounting plate 102 comprises a first section 112 and the metal plate structure comprises a first section 114. The first section of the metal mounting plate is parallel with and in contact with the first section of the metal plate structure. The first section of the metal mounting plate is welded onto the first section of the metal plate structure. The first section of the metal mounting plate and the first section of the metal plate structure surround the full circumference of the woven wire mesh.
Figure 5 shows a view on a cross section 500 taken perpendicularly to the long sides of the rectangular circumference with rounded short sides of an alternative burner according to the invention. The burner comprises a metal mounting plate 502, a burner deck 504 and a metal plate structure 506. The metal mounting plate has a plane section 503 for mounting the burner in a heating appliance, e.g. in a boiler. The metal mounting plate comprises an upstanding ridge 520 at the opening through which the woven wire mesh is inserted through the metal mounting plate. The upstanding ridge is oriented in the direction opposite to the flange of the woven wire mesh.
The burner deck consists out of a woven wire mesh onto which the flames are stabilized when the burner is in use. The burner deck has a convex shape over its full surface. The circumference of the burner deck has the shape of a rectangle of which the two short sides have been continuously rounded.
Part of the metal plate structure is perforated for the premix gas to flow through the perforations 508 before the premix gas flows through the woven wire mesh. All zones of the metal plate structure provided with perforations are provided at a distance of at least 1 mm from the woven wire mesh. The metal mounting plate has an opening. The woven wire mesh is inserted through the opening of the metal mounting plate. The woven wire mesh is bent, such that a flange 510 parallel with the plane section of the metal mounting plate is provided. The flange 510 is held between the metal mounting plate and the metal plate structure such that play of the flange relative to the metal mounting plate and relative to the metal plate structure is present.
The metal plate structure 506 comprises an upstanding edge 522 contacting the metal mounting plate 502. At these contacting points, the metal plate structure 506 is welded to the metal mounting plate 502.

Claims

Premix gas burner, comprising
- a metal mounting plate (102, 502), wherein the metal mounting plate has a plane section (103, 503) for mounting the burner in a heating appliance;

- a burner deck (104, 504), wherein the burner deck comprises - and preferably consists out of

- a woven wire mesh onto which the flames are stabilized when the burner is in use;

- a metal plate structure (106, 506), wherein at least part of the metal plate structure is perforated for the premix gas to flow through the perforations (108, 508) before the premix gas flows through the woven wire mesh;
wherein the metal mounting plate comprises an opening;
wherein the woven wire mesh is inserted through the opening of the metal mounting plate; wherein the woven wire mesh is bent, such that a flange (110, 510) parallel with the plane section of the metal mounting plate is provided;
wherein the circumference of the woven wires mesh has the shape of a rectangle of which the two short sides have been - preferably continuously - rounded;
characterized in that the flange is held between the metal mounting plate and the metal plate structure such that play of the flange relative to the metal mounting plate and relative to the metal plate structure is present; and
wherein no flange is provided along the two short sides of the rectangular shape of the circumference of the woven wire mesh.
A premix gas burner as in claim 1, wherein the flange is along the circumference of the woven wire mesh split in a plurality of flange segments.
Premix gas burner as in any of the preceding claims, wherein the burner deck is provided in a convex shape; preferably wherein the burner deck is provided in a convex shape over the full surface of the burner deck provided for stabilizing the flames.
Premix gas burner as in any of preceding claims 1 - 3, wherein all zones of the metal plate structure provided with perforations are provided at a distance from the woven wire mesh.
Premix gas burner as in any of preceding claims 1 - 3, wherein all zones of the metal plate structure provided with perforations are contacting the woven wire mesh.
Premix gas burner as in any of the preceding claims, wherein the full surface of the burner deck onto which flames are stabilized when the burner is in use, is provided by the woven wire mesh.
Premix gas burner as in any of the preceding claims,
wherein the metal mounting plate comprises a first section (112),
wherein the metal plate structure comprises a first section (114),
wherein the first section of the metal mounting plate is parallel with and in contact with the first section of the metal plate structure;
wherein the first section of the metal mounting plate is welded onto the first section of the metal plate structure, e.g. by means of spot welds.
Premix gas burner as in any of the preceding claims,
wherein the metal mounting plate comprises an upstanding ridge (520) at the opening through which the woven wire mesh is inserted through the metal mounting plate;
preferably the upstanding ridge is oriented in the direction opposite to the flange of the woven wire mesh.
Premix gas burner as in any of the preceding claims, wherein in the woven wire mesh the bent angle providing the flange of the woven wire mesh is at least 90°.
Condensing boiler comprising a premix gas burner as in any of the preceding claims 1 - 9.