WO2022161949A1

WO2022161949A1 - Wire mesh premix burner

Info

Publication number: WO2022161949A1
Application number: PCT/EP2022/051634
Authority: WO
Inventors: Geert Folkers; Dinand LAMBERS; Marc BUS; Mathieu VERHOOGT; Camillo Marino Josef Hogenbirk; Gertjan Zwiggelaar
Original assignee: Bekaert Combustion Technology B.V.
Priority date: 2021-01-29
Filing date: 2022-01-25
Publication date: 2022-08-04
Also published as: EP4285053A1; NL2027464B1

Abstract

The invention pertains to a wire mesh premix burner, comprising a non-cylindrical burner deck, having a high temperature region and a temperature gradient region, and a woven wire mesh. The woven wire mesh comprises a primary portion which forms the high temperature region of the burner deck and a secondary portion which forms the temperature gradient region of the burner deck. The secondary portion has a first section and a second section, both having a longitudinal direction. The longitudinal direction of the second section extends perpendicular to the longitudinal direction of the first section. The first section comprises a plurality of bulges having a cross sectional shape in a first direction in the form of a wave. The second section comprises a plurality of bulges, having a cross sectional shape in a second direction in the form of a wave. The second direction is perpendicular to the first direction.

Description

Wire mesh premix burner

The invention pertains to a wire mesh premix burner.

In a premix burner, a mixture of air and combustible gas is supplied to a gas distribution chamber. This mixture of air and combustible gas is in the art commonly referred to as “premix” or “premix gas”. The premix gas flows out of the gas distribution chamber to a burner deck. The burner deck comprises gas outflow openings. The premix gas passes through these gas outflow openings as it flows out of the gas distribution chamber. Once the premix gas has passed through the gas outflow openings, it is combusted by a flame that - after ignition - is present on the outer surface of the burner deck.

Different types of burner decks are known. A burner deck for example comprises or is formed by a steel plate with holes in it that serve as gas outflow openings. In another type of premix burner, the burner deck is or comprises a fibrous metal material and/or a knitted metal material. The fibrous metal or knitted metal burner deck may or may not be supported by a distributor, which distributor is for example formed by a steel plate with holes or by a woven wire mesh. A further different type of burner deck comprises or is formed by a wire mesh, e.g. a woven wire mesh. Such a mesh comprises warp wires and weft wires. Adjacent warp wires and adjacent weft wires are spaced apart from each other, therewith forming gas outflow openings between adjacent wires. Each gas outflow opening is delimited by two mutually adjacent warp wires and two mutually adjacent weft wires. Warp wires and weft wires normally extend perpendicular to each other.

Burner decks can be essentially tubular and/or cylindrical, for example having a circular or elliptical cross section and a closed end portion at the tube or cylinder. The size of the cross section may be constant or may change over the length of the cylindrical and/or tubular burner. Alternatively, burner decks can be non-cylindrical, in particular essentially planar, having a generally flat, curved or double curved shape (double curved means that it has a curvature in two different cross sectional directions). A non-cylindrical burner is also nontubular. An essentially planar burner deck may be have structures, elements or shapes protruding from the flat, curved or double-curved shape.

Different types of burner decks have a different behavior under the thermal load that they are subjected to and also have different problems.

Wire mesh premix burners are known to suffer from integrity problems in the wire mesh, e.g. local breaking of one or more warp wires and/or weft wires due to the thermal and/or mechanical load on these wires during use of the premix burner. LIS2013/059257 proposes to provide the wire mesh of the burner deck with a plurality of parallel elongated rigidizing bulges in order to reduce the flexibility of the wire mesh and to reduce vibration of wire mesh. The rigidizing bulges are present in the center of the burner deck and all extend in the same direction.

The invention aims to provide an improved wire mesh premix burner which is less susceptible to integrity problems of the wire mesh burner deck.

This object is obtained by a wire mesh premix burner, comprising: a non-cylindrical burner deck, wherein the burner deck has a high temperature region and a temperature gradient region adjacent to the high temperature region, wherein the burner deck comprises a woven wire mesh, which woven wire mesh comprises warp wires and weft wires which extend perpendicular to each other, and which woven wire mesh has gas outflow openings which are delimited by adjacent warp wires and adjacent weft wires, wherein the woven wire mesh comprises a primary portion which forms the high temperature region of the burner deck and a secondary portion which forms the temperature gradient region of the burner deck, wherein the secondary portion of the woven wire mesh has a first section having a longitudinal direction and a second section also having a longitudinal direction, wherein the longitudinal direction of the second section extends perpendicular to the longitudinal direction of the first section, wherein the first section comprises a plurality of bulges, which bulges have a cross sectional shape in a first direction in the form of a wave, and wherein the second section comprises a plurality of bulges, which bulges have a cross sectional shape in a second direction in the form of a wave, wherein the second direction is perpendicular to the first direction.

The invention pertains to a wire mesh premix burner having a burner deck, which burner deck comprises a woven mesh. In use of the wire mesh premix burner, after ignition a flame is present on a free surface of the burner deck. The burner deck of the wire mesh premix burner is non-cylindrical. The free surface faces outwards of the wire mesh premix burner. The burner deck may also comprise one or more areas which in use do not have a flame right on top of it, e.g. areas at or near the edges of the burner deck, which are located at or close to the areas where the burner deck is supported in the premix burner. The burner deck is for example rectangular or square, optionally rectangular or square with rounded edges. In wire mesh premix burners, the burner deck has a high temperature region which is for example located in the center of the burner deck. In use, the high temperature region has a high temperature (e.g. between 500°C and 900°C) with little or no local temperature variations. In use, the edges of the burner deck are significantly cooler than the high temperature region. Between the high temperature region and the edges, a temperature gradient region is present which forms the transition between the high temperature region and the cool edges. Optionally, a low temperature region is present between the temperature gradient region and an edge of the burner deck. In the low temperature region, there is little or no local temperature variation when the wire mesh premix burner is in use.

The high temperature region and the temperature gradient region can for instance be identified by thermal imaging when the wire mesh premix burner is in use, or by calculations on a finite element model of the woven wire mesh.

The burner deck comprises a woven wire mesh. The woven wire mesh comprises warp wires and weft wires which extend perpendicular to each other. The woven wire mesh has gas outflow openings which are delimited by adjacent warp wires and adjacent weft wires. In use, premix gas flows though these outflow openings to the free surface, out of the wire mesh premix burner. This premix gas is ignited to form a flame on the free surface of the burner deck, which flame is fed by a continuing flow of premix gas through the outflow openings of the woven wire mesh of the burner deck.

The woven wire mesh comprises a primary portion which forms the high temperature region of the burner deck. The woven wire mesh further comprises a secondary portion which forms the temperature gradient region of the burner deck.

For example, the primary portion has a rectangular shape. For example, the secondary portion extends around the circumference of the primary portion, e.g. around a part of the circumference of the primary portion or around the entire circumference of the primary portion.

For example, the primary portion is present in the center of the woven wire mesh, and the secondary portion extends around the circumference of the primary portion, e.g. around a part of the circumference of the primary portion or around the entire circumference of the primary portion.

Optionally, the woven wire mesh further comprises a tertiary region, which forms a low temperature region of the burner deck, adjacent to the secondary portion of the woven wire mesh. The secondary portion of the woven wire mesh has a first section. The first section has a longitudinal direction. The first section for example has a rectangular or trapezoidal shape. The secondary portion also comprises a second section. The second section has a longitudinal direction. The second section for example has a rectangular or trapezoidal shape. The longitudinal direction of the second section extends perpendicular to the longitudinal direction of the first section.

For example, the width of the first section, measured perpendicular to the longitudinal direction of the first section, is 35% or less of the width of the primary portion measured in the same direction. For example, the width of the second section, measured perpendicular to the longitudinal direction of the second section, is 35% or less of the width of the primary portion measured in the same direction.

Optionally, the longitudinal direction of the first section extends parallel to an edge of the woven wire mesh adjacent to the first section. Optionally, the longitudinal direction of the second section extends parallel to an edge of the woven wire mesh adjacent to the second section. Optionally, the longitudinal direction of the first section extends parallel to an edge of the woven wire mesh adjacent to the first section and the longitudinal direction of the second section extends parallel to an edge of the woven wire mesh adjacent to the second section.

Optionally, the first section and the second section do not overlap each other. Alternatively, the first section and the second section partly overlap each other, for example on one end of each.

The first section of the secondary portion comprises a plurality of bulges. These bulges have a cross sectional shape in a first direction in the form of a wave. The cross sectional shape can be a single wave or multiple waves. The first direction is optionally parallel to the longitudinal direction of the first section, and/or to an edge of the burner deck adjacent to the first section. Alternatively, the first direction is optionally at an angle of 30° - 60°, e.g. 40°- 50 e.g. 45° relative to the longitudinal direction of the first section, and/or to an edge of the burner deck adjacent to the first section.

The second section of the secondary portion comprises a plurality of bulges. These bulges have a cross sectional shape in a second direction in the form of a wave, wherein the second direction is perpendicular to the first direction. The cross sectional shape can be a single wave or multiple waves. The second direction is optionally parallel to the longitudinal direction of the second section, and/or to an edge of the burner deck adjacent to the second section. Alternatively, the second direction is optionally at an angle of 30° - 60°, e.g. 40°- 50 e.g. 45° relative to the longitudinal direction of the second section, and/or to an edge of the burner deck adjacent to the second section. Optionally, the first direction is parallel to the longitudinal direction of the first section and the second direction is parallel to the longitudinal direction of the second section. Optionally, the first direction is parallel to an edge of the burner deck adjacent to the first section and the second direction is parallel to an edge of the burner deck adjacent to the second section.

Optionally, the first direction is at an angle of 45° relative to the longitudinal direction of the first section and the second direction is at an angle of 45° relative to the longitudinal direction of the second section. Optionally, the first direction is at an angle of 45° relative to an edge of the burner deck adjacent to the first section and the second direction is at an angle of 45° relative to an edge of the burner deck adjacent to the second section.

Optionally, the cross sectional shape of the bulges in the first section and/or the second section is a smooth wave (i.e. a wave not having sharp corners), e.g. a sine wave or a parabolic wave or a spline or a catenary.

Optionally, at least one bulge which is present in the secondary portion of the woven wire mesh extends into the primary portion and/or into a tertiary portion of the woven wire mesh (if a tertiary portion is present). Optionally, all bulges which are present in the secondary portion of the woven wire mesh extend into the primary portion and/or into a tertiary portion of the woven wire mesh (if a tertiary portion is present). Optionally, at least one bulge which is present in the secondary portion of the woven wire mesh extends up to an edge of the woven wire mesh. Optionally, all bulges which are present in the secondary portion of the woven wire mesh extend up to an edge of the woven wire mesh.

Optionally, the woven wire mesh is self-supporting, i.e. the woven wire mesh is only supported at its edges.

Optionally, at least the primary portion of the woven wire mesh is self-supporting, i.e. the primary portion of the woven wire mesh does not directly contact a support of the woven wire mesh.

Optionally, the woven wire mesh is supported by supports which are spaced apart from each other by at least a distance of 25% of a main dimension of the woven wire mesh, such as a widths or length of the woven wire mesh. The thickness of the warp wires and the thickness of the weft wires are not considered to be main dimensions of the woven wire mesh. Optionally, the supports are spaced apart from each other by at least a distance of 50% of a main dimension of the woven wire mesh

In the wire mesh premix burner according to the invention, it has been observed that the woven wire mesh of the burner deck shows less integrity problems than the woven wire mesh of known wire mesh premix burners. It is suspected that the temperature variation in the burner deck during use of the wire mesh premix burner causes several problems related to local thermal expansion of the wires, local variations in rigidity of the wires and local variation in material stresses in the wires. These issues may cause integrity problems in the wire mesh, e.g. due to local breaking of one or more warp wires and/or weft wires. The inventors suspect that the bulges in the first and second section of the woven wire mesh mitigate these problems to at least some extent.

For example, the high temperature region of the burner deck may be located in the center of the burner deck and the temperature gradient region may surround the high temperature region. The parts of the warp wires and weft wires that are present in the primary portion of the woven wire mesh (and therewith in the high temperature region of the burner deck) are likely to thermally expand more than the parts of those warp wires and weft wires that are located in the secondary portion of the woven wire mesh (and therewith in the temperature gradient region of the burner deck). However, as the part of the warp wires and the weft wires in the primary portion of the woven wire mesh are warmer than the parts of the warp wires and the weft wires in the secondary portion of the woven wire mesh, the parts of the warp wires and the weft wires in secondary portion of the woven wire mesh are more rigid (i.e. have a larger module of elasticity) than the parts of the warp wires and the weft wires in the primary portion of the woven wire mesh. This leads to mechanical stresses in the warp wires and the weft wires. As the wire mesh premix burner is for example used in a heating system which is subjected to many starts and stops and power modulations, these mechanical stresses may lead to fatigue failures of wires in the woven wire mesh.

In addition, the relatively high thermal expansion of the parts of the warp wires and the weft wires in the primary portion of the woven wire mesh in combination with the more rigid parts of the warp wires and weft wires in the secondary portion of the woven wire mesh may lead to a displacement of the primary part of the woven wire mesh in an outward direction, perpendicular to the warp wires and weft wires. This displacement can easily be a couple of millimeters, and may cause problems for example because the woven wire mesh of the burner deck may come into contact with system parts that are located close to the burner deck such as an ionizing pin and/or a sensor and/or a spark electrode.

In the wire mesh premix burner according to the invention, the bulges in the first section and the second section of the secondary portion of the woven wire mesh provide flexibility in the woven wire mesh, allowing the parts of the warp wires and the weft wires in the primary portion of the woven wire mesh to thermally expand with lower levels of mechanical stress and lower outward displacement of the primary portion of the woven wire mesh than in known wire mesh premix burners. In an embodiment of the wire mesh premix burner according to the invention, the secondary portion of the woven wire mesh further comprises a third section, which is located opposite to the first section. The third section has a longitudinal direction. The third section comprises a plurality of bulges, which bulges have a cross sectional shape in the first direction in the form of a wave.

Alternatively or in addition, in this embodiment the secondary portion of the woven wire mesh further comprises a fourth section, which is located opposite to the second section. The fourth section has a longitudinal direction. The fourth section comprises a plurality of bulges, which bulges have a cross sectional shape in the second direction in the form of a wave.

Optionally, the longitudinal direction the first section and the longitudinal direction of the third section are parallel to each other. Optionally, the longitudinal direction the second section and the longitudinal direction of the fourth section are parallel to each other.

Optionally, the longitudinal direction of the third section and the first direction are parallel to each other.

Optionally, the longitudinal direction of the fourth section and the second direction are parallel to each other.

Optionally, in this embodiment the secondary portion of the woven wire mesh has a rectangular shape having four sides, and the first section is located on a first side of the rectangular shape, the second section is located on the second side of the rectangular shape (the second side of the rectangular shape being perpendicular to the first side of the rectangular shape), the third section is located on the third side of the rectangular shape (the third side of the rectangular shape being parallel to the first side of the rectangular shape) and the fourth section is arranged on the fourth side of the rectangular shape (the fourth side of the rectangular shape being parallel to the second side of the rectangular shape).

In this embodiment, the shape of the woven wire mesh provides additional flexibility on four sides of the primary portion to allow thermal expansion of the parts of the warp wires and weft wires in the primary portion of the woven wire mesh.

In an embodiment of the wire mesh premix burner according to the invention, a bulge in the first section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the first section.

Optionally, multiple bulges are present in the first section of the secondary portion of the woven wire mesh, each bulge of these multiple bulges having an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the first section.

This embodiment has shown to be an effective and practical way of realizing the invention. In an embodiment of the wire mesh premix burner according to the invention, the plurality of bulges in the first section includes at least two bulges, each having an elongated shape with a longitudinal axis, with the longitudinal axes of the elongated shape of these bulges being parallel to each other. Optionally, these elongated axes extend perpendicular to the longitudinal axis of the first section.

This embodiment has shown to be an effective and practical way of realizing the invention.

In an embodiment of the wire mesh premix burner according to the invention, a bulge in the first section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the first section, and a bulge in the second section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the second section.

Optionally, alternatively or in addition, multiple bulges are present in the second section of the secondary portion of the woven wire mesh, each bulge of these multiple bulges having an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the second section.

Optionally, all bulges in the first section have the same length.

Optionally, all bulges in the second section have the same length.

Optionally, all bulges in the first section have the same length and all bulges in the second section have the same length. The length of the bulges in the first section may be the same as or different from the length of the bulges in the second section.

In an embodiment of the wire mesh premix burner according to the invention, the secondary portion of the woven wire mesh further comprises a third section, which is located opposite to the first section. The third section has a longitudinal direction. The third section comprises a plurality of bulges, which bulges have a cross sectional shape in the first direction in the form of a wave. Optionally or in addition, in this embodiment the secondary portion of the woven wire mesh further comprises a fourth section, which is located opposite to the second section. The fourth section has a longitudinal direction. The fourth section comprises a plurality of bulges, which bulges have a cross sectional shape in the second direction in the form of a wave.

In this embodiment, a bulge in the first section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the first section, and a bulge in the third section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the third section.

Optionally or in addition, in case a fourth section is present, a bulge in the second section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the second section, and a bulge in the fourth section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the fourth section.

The elongated bulges in three or four sections of the secondary portion of the woven wire mesh further improve the ability of the woven wire mesh to cope with the thermal expansion of the portions of the warp wires and the weft wires in the primary region.

In an embodiment of the wire mesh premix burner according to the invention, the first section comprises a bulge which has also a cross sectional shape in a direction perpendicular to the first direction in the form of a wave.

So, in this embodiment, the first section comprises a bulge which has a cross sectional shape in the form of a wave when the cross section is taken in the first direction and also when the cross section is taken in the second direction. This results for example in a domeshaped bulge.

Optionally, in this embodiment also at least one of the second section and/or the fourth section comprises a bulge which has also a cross sectional shape in a direction perpendicular to the second direction (i.e. in the first direction) in the form of a wave. So, in this case, the at least one of the second section and/or fourth section comprises a bulge which has a cross sectional shape in the form of a wave when the cross section is taken in the first direction and also when the cross section is taken in the second direction. Optionally, the bulge of the second section and/or the bulge of the fourth section is a dome-shaped bulge.

Optionally, in this embodiment also the third section comprises a bulge which has also a cross sectional shape in a direction perpendicular to the first direction (i.e. in the second direction) in the form of a wave. So, in this case, the third section comprises a bulge which has a cross sectional shape in the form of a wave when the cross section is taken in the first direction and also when the cross section is taken in the second direction. Optionally, the bulge of the third section is a dome-shaped bulge. This embodiment provides an alternative or additional shape for the bulges which has shown to be effective in practical situations.

In an embodiment of the wire mesh premix burner according to the invention, the primary portion of the woven wire mesh extends in a flat plane, or in a curved plane, or in a double curved plane.

The invention has shown to function well with embodiments in which the primary portion has such a shape.

In an embodiment of the wire mesh premix burner according to the invention, the primary portion of the woven wire mesh comprises a plurality of bulges.

Optionally, the bulges in the primary portion of the woven wire mesh extend from a flat, curved or double curved plane.

In this embodiment, the increased flexibility of the woven wire mesh in the direction of the warp wires and weft wires is present also in the primary portion of the woven wire mesh. In addition, the stiffness in the direction perpendicular to the plane from which the bulges extend is increased in order to reduce sagging of the primary portion of the woven wire mesh.

In an embodiment of the wire mesh premix burner according to the invention, the primary portion of the woven wire mesh comprises a plurality of bulges, and the primary portion of the woven wire mesh comprises a bulge which has a cross sectional shape in the first direction in the form of a wave.

Alternatively or in addition, the primary portion of the woven wire mesh comprises a bulge which has a cross sectional shape in the second direction in the form of a wave,

Alternatively or in addition, the primary portion of the woven wire mesh comprises a bulge which has a cross sectional shape in the first direction in the form of a wave and a cross sectional shape in the second direction in the form of a wave. Optionally, this bulge is a dome-shaped bulge.

In this embodiment, the increased flexibility of the woven wire mesh in the direction of the warp wires and weft wires is present also in the primary portion of the woven wire mesh. In addition, the stiffness in the direction perpendicular to the plane from which the bulges extend is increased in order to reduce sagging of the primary portion of the woven wire mesh. The bulges having this particular shape provide a reliable way of achieving the desired effect.

In an embodiment of the wire mesh premix burner according to the invention, the primary portion of the woven wire mesh comprises a plurality of bulges, and an array of bulges is present in the primary portion of the woven wire mesh. The array of bulges extends along a line which is parallel to the longitudinal direction of the first section, or along a line which is perpendicular to the longitudinal direction of the first section, or along a line which is at an angle relative to the longitudinal direction of the first section, for example at an angle of 30°- 60° relative to the longitudinal direction of the first section, optionally at an angle of 40°- 50°, for example at an angle of 45°.

Optionally, the primary portion of the woven wire mesh comprises a bulge which has a cross sectional shape in the first direction in the form of a wave.

Optionally, alternatively or in addition, the primary portion of the woven wire mesh comprises a bulge which has a cross sectional shape in the second direction in the form of a wave,

Optionally, alternatively or in addition, the primary portion of the woven wire mesh comprises a bulge which has a cross sectional shape in the first direction in the form of a wave and a cross sectional shape in the second direction in the form of a wave. Optionally, this bulge is a dome-shaped bulge. Optionally, all bulges in the primary portion of the woven wire mesh have a cross sectional shape in the first direction in the form of a wave and a cross sectional shape in the second direction in the form of a wave. Optionally, all bulges are domeshaped bulges.

The array of bulges provides additional flexibility, allowing the woven wire mesh to better deal with the thermal extension of the warp wires and weft wires in the primary portion of the woven wire mesh during use of the wire mesh premix burner.

In an embodiment of the wire mesh premix burner according to the invention, the primary portion of the woven wire mesh comprises a plurality of bulges, and a plurality of bulges in the primary portion of the woven wire mesh is arranged in a rectangular grid which has a first main direction and a second main direction which is perpendicular to the first main direction.

In this embodiment, the first main direction is parallel to the longitudinal direction of the first section, or perpendicular to the longitudinal direction of the first section, or extends at an angle relative to the longitudinal direction of the first section, which angle is for example 30°- 60° relative to the longitudinal direction of the first section, optionally 40° - 50°, for example 45°.

Optionally, alternatively or in addition, the primary portion of the woven wire mesh comprises a bulge which has a cross sectional shape in the second direction in the form of a wave, Optionally, alternatively or in addition, the primary portion of the woven wire mesh comprises a bulge which has a cross sectional shape in the first direction in the form of a wave and a cross sectional shape in the second direction in the form of a wave. Optionally, this bulge is a dome-shaped bulge. Optionally, all bulges in the primary portion of the woven wire mesh have a cross sectional shape in the first direction in the form of a wave and a cross sectional shape in the second direction in the form of a wave. Optionally, all bulges are domeshaped bulges.

The arrangement of bulges in a grid provides additional flexibility in at least two directions, allowing the woven wire mesh to better deal with the thermal extension of the warp wires and weft wires in the primary portion of the woven wire mesh during use of the wire mesh premix burner.

In an embodiment of the wire mesh premix burner according to the invention, the woven wire mesh comprises an elongated vertex bulge having a longitudinal axis, which vertex bulge is arranged at a transition area between the first section and the second section of the secondary portion of the woven wire mesh. The longitudinal axis of the vertex bulge extends at an angle relative to the longitudinal direction of the first section, for example an angle of 30° - 60°, e.g. an angle of 40° - 50°, for example 45°.

For example, if the secondary portion of the woven wire mesh has a rectangular shape, and the first section is present on one side of the rectangle and the second section is present on the a second side which extends perpendicular to the first side, the transition area encompasses the corner of the rectangular shape between the first side and the second side of the rectangular shape. For example, the vertex bulge is located at the corner of the rectangular shape between the first side and the second side of the rectangular shape and the longitudinal axis of the vertex bulge extends at an angle relative to the longitudinal direction of the first section, for example an angle of 30° - 60°, e.g. an angle of 40° - 50°, for example 45°.

The vertex bulge provides additional flexibility to the woven wire mesh, allowing it to better deal with the thermal extension of the warp wires and weft wires in the primary portion of the woven wire mesh during use of the wire mesh premix burner.

In an embodiment of the wire mesh premix burner according to the invention, the primary portion of the woven wire mesh is free of bulges.

This allows a compact design of the wire mesh premix burner. In addition, it allows to keep the distance constant or at least substantially constant between the burner deck and e.g. ionizing pin and/or a sensor and/or a spark electrode which is/are placed adjacent to the burner deck. In an embodiment of the wire mesh premix burner according to the invention, at least one of the bulges extends into the primary portion of the woven wire mesh.

Optionally, the woven wire mesh is free of bulges that extend in the primary portion only. So, the only bulges that are present in the primary portion of the woven wire mesh, are those that extend into the secondary portion of the woven wire mesh as well. There are no bulges which are entirely arranged within the primary portion of the woven wire mesh.

In an embodiment of the wire mesh premix burner according to the invention, the warp wires and/or the weft wires of the woven wire mesh extend at an angle relative to the longitudinal direction of the first section, e.g. at an angle of 30°- 60°, optionally at an angle of 40° - 50°, for example at an angle of 45°.

Alternatively or in addition, the warp wires and/or the weft wires of the woven wire mesh extend at an angle relative to the longitudinal direction of the second section, e.g. at an angle of 30°- 60°, optionally at an angle of 40° - 50°, for example at an angle of 45°.

Tests results suggest that this provides a further optimisation of the fatigue resistance of the woven wire mesh.

In an embodiment of the wire mesh premix burner according to the invention, the warp wires or the weft wires of the woven wire mesh extend parallel to the longitudinal direction of the first section, and the other one of the warp wires or the weft wires of the woven wire mesh extend parallel to the longitudinal direction of the second section.

This provides an economical design of the wire mesh burner, allowing optimal cutting of the woven wire mesh in the manufacturing process.

In an embodiment of the wire mesh premix burner according to the invention, the bulges in at least the first section and the second section of the secondary portion of the woven wire mesh are elongated bulges, which have a length of 30% or less, e.g. 25% or less, of the width and/or length of the woven wire mesh.

Optionally, in a variant of this embodiment, the woven wire mesh has a rectangular or square shape, wherein the longitudinal direction of the first section extends parallel to a first side of that rectangular shape and the longitudinal direction of the second section extends parallel to a second side of that rectangular shape, the first side and the second side extending perpendicular to each other. In this variant, the longitudinal direction of the bulges in the first section is parallel to the second direction i.e. perpendicular to the first direction, and the longitudinal direction of the bulges in the second section is parallel to the first direction i.e. perpendicular to the second direction. In this variant, the length of the elongated bulges in the first section is 30% or less than the length of the second side of the woven wire mesh, e.g. 25% or less, optionally 20% or less. Alternatively or in addition, the length of the elongated bulges in the second section is 30% or less than the length of the first side of the woven wire mesh, e.g. 25% or less, optionally 20% or less.

This embodiment and its variant allow thermal expansion of the bulges without the introduction of significant additional material stresses woven wire mesh due to this expansion.

In an embodiment of the wire mesh premix burner according to the invention, the wire mesh premix burner further comprises a housing and a gas distribution chamber which is accommodated in the housing. The gas distribution chamber is in fluid communication with the burner deck, allowing premix gas to flow from the gas distribution chamber to the burner deck and through the gas outflow openings of the woven wire mesh of the burner deck.

Optionally, in this embodiment a gas diffuser is provided, which is preferably arranged between the gas distribution chamber and the burner deck. The gas diffuser distributes the premix gas over the burner deck, in particular over the woven wire mesh of the burner deck. Preferably, the gas diffuser does not provide structural support to the woven wire mesh, i.e. the gas diffuser does not touch the woven wire mesh.

Optionally, the woven wire mesh is arranged onto or in the housing in a floating manner, i.e. the woven wire mesh can expand freely relative to the housing in at least one direction, optionally in two directions. Preferably, the woven wire mesh is arranged onto or in the housing in a floating manner such that the woven wire mesh can expand freely in the direction of the warp wires and/or the weft wires, and/or at an angle of 40 °- 50 °, e.g. 45° relative to the warp wires and/or the weft wires.

The invention further pertains to a heating system comprising a wire mesh premix burner as described above. The heating system for example comprises a heat exchanger, comprising a flow channel which is adapted to contain a heating medium. The wire mesh premix burner is arranged to heat the heating medium in the heat exchanger. The heating medium for example is or contains water. In another example, the heating system is designed such that the wire mesh premix burner directly heats a reservoir of water which water is for example used as hot tap water or hot water for heating a building.

In an embodiment of the wire mesh premix burner according to the invention, the bulges in the first section of the secondary portion of the woven wire mesh have an elongated shape with a longitudinal axis. In addition, the bulges in the second section of the secondary portion of the woven wire mesh also have an elongated shape with a longitudinal axis. In this embodiment, the longitudinal axes of the elongated bulges in the second section of the secondary portion of the woven wire mesh extend at an angle relative to the longitudinal axes of the elongated bulges in the first section of the secondary portion of the woven wire mesh. For example, the longitudinal axes of the elongated bulges in the second section of the secondary portion of the woven wire mesh extend perpendicular to the longitudinal axes of the elongated bulges in the first section of the secondary portion of the woven wire mesh.

Optionally, the longitudinal axes of the bulges in the first section of the secondary portion of the woven wire mesh are parallel too each other.

Optionally, the longitudinal axes of the bulges in the second section of the secondary portion of the woven wire mesh are parallel too each other.

Optionally, all bulges in the first section have the same length.

Optionally, all bulges in the second section have the same length.

Optionally, at least one of the bulges extends into the primary portion of the woven wire mesh. Optionally, the woven wire mesh is free of bulges that extend in the primary portion only. So, the only bulges that are present in the primary portion of the woven wire mesh, are those that extend into the secondary portion of the woven wire mesh as well. There are no bulges which are entirely arranged within the primary portion of the woven wire mesh.

Optionally, the primary portion of the woven wire mesh is free of bulges.

Optionally, the primary portion of the woven wire mesh extends in a flat plane, or in a curved plane, or in a double curved plane.

Optionally, the bulges in at least the first section and/or the second section of the secondary portion of the woven wire have a length of 30% or less, e.g. 25% or less, of the width and/or length of the woven wire mesh.

Optionally, the woven wire mesh has a rectangular or square shape, wherein the longitudinal direction of the first section extends parallel to a first side of that rectangular shape and the longitudinal direction of the second section extends parallel to a second side of that rectangular shape, the first side and the second side extending perpendicular to each other.

Optionally, the secondary portion of the woven wire mesh further comprises a third section, which is located opposite to the first section. The third section has a longitudinal direction. The third section comprises a plurality of elongated bulges, which bulges have a cross sectional shape in the first direction in the form of a wave. Optionally, alternatively or in addition, in this embodiment the secondary portion of the woven wire mesh further comprises a fourth section, which is located opposite to the second section. The fourth section has a longitudinal direction. The fourth section comprises a plurality of elongated bulges, which bulges have a cross sectional shape in the second direction in the form of a wave.

Optionally, the longitudinal direction the first section and the longitudinal direction of the third section are parallel to each other. Optionally, the longitudinal direction the second section and the longitudinal direction of the fourth section are parallel to each other. Optionally, the longitudinal direction of the third section and the first direction are parallel to each other. Optionally, the longitudinal direction of the fourth section and the second direction are parallel to each other.

Optionally, the warp wires and/or the weft wires of the woven wire mesh extend at an angle relative to the longitudinal direction of the first section, e.g. at an angle of 30°- 60°, optionally at an angle of 40° - 50°, for example at an angle of 45°.

Optionally, the woven wire mesh comprises an elongated vertex bulge having a longitudinal axis, which vertex bulge is arranged at a transition area between the first section and the second section of the secondary portion of the woven wire mesh. The longitudinal axis of the vertex bulge extends at an angle relative to the longitudinal direction of the first section, for example an angle of 30° - 60°, e.g. an angle of 40° - 50°, for example 45°. For example, if the secondary portion of the woven wire mesh has a rectangular shape, and the first section is present on one side of the rectangle and the second section is present on the a second side which extends perpendicular to the first side, the transition area encompasses the corner of the rectangular shape between the first side and the second side of the rectangular shape. For example, the vertex bulge is located at the corner of the rectangular shape between the first side and the second side of the rectangular shape and the longitudinal axis of the vertex bulge extends at an angle relative to the longitudinal direction of the first section, for example an angle of 30° - 60°, e.g. an angle of 40° - 50°, for example 45°.

In an embodiment of the wire mesh premix burner according to the invention, the bulges in the first section also have a cross sectional shape in a direction perpendicular to the first direction in the form of a wave, and the bulges in the second section also have a cross sectional shape in a direction perpendicular to the second direction in the form of a wave So, in this embodiment, the bulges in the first section have a cross sectional shape in the form of a wave when the cross section is taken in the first direction and also when the cross section is taken in the second direction, and the bulges in the second section have a cross sectional shape in the form of a wave when the cross section is taken in the second direction and also when the cross section is taken in the first direction. This results for example in dome-shaped bulges being present in the first section and in the second section.

Optionally, the secondary portion of the woven wire mesh further comprises a third section, which is located opposite to the first section. Optionally, alternatively or in addition, in this embodiment the secondary portion of the woven wire mesh further comprises a fourth section, which is located opposite to the second section. The bulges in the third second and in the fourth section have a cross sectional shape in a direction perpendicular to the first direction in the form of a wave and also have a cross sectional shape in a direction perpendicular to the second direction in the form of a wave. This results for example in a dome-shaped bulges being present in the third section and/or in the fourth section.

Optionally, the primary portion of the woven wire mesh comprises a plurality of bulges. Optionally, the bulges in the primary portion of the woven wire mesh extend from a flat, curved or double curved plane.

Optionally, at least one bulge the primary portion of the woven wire mesh has a cross sectional shape in the first direction in the form of a wave and a cross sectional shape in the second direction in the form of a wave. Optionally, all bulges in the primary portion of the woven wire mesh have a cross sectional shape in the first direction in the form of a wave and a cross sectional shape in the second direction in the form of a wave. This results for example in dome-shaped bulges being present in the primary portion of the woven wire mesh.

Optionally, the primary portion of the woven wire mesh comprises a plurality of bulges, and an array of bulges is present in the primary portion of the woven wire mesh. The array of bulges extends along a line which is parallel to the longitudinal direction of the first section, or along a line which is perpendicular to the longitudinal direction of the first section, or along a line which is at an angle relative to the longitudinal direction of the first section, for example at an angle of 30°- 60° relative to the longitudinal direction of the first section, optionally at an angle of 40°- 50°, for example at an angle of 45°. Optionally, at least one bulge is a domeshaped bulge or all bulges are dome-shaped bulges.

Optionally, the primary portion of the woven wire mesh comprises a plurality of bulges, and a plurality of bulges in the primary portion of the woven wire mesh is arranged in a rectangular grid which has a first main direction and a second main direction which is perpendicular to the first main direction. Optionally, the first main direction is parallel to the longitudinal direction of the first section, or perpendicular to the longitudinal direction of the first section, or extends at an angle relative to the longitudinal direction of the first section, which angle is for example 30°- 60° relative to the longitudinal direction of the first section, optionally 40° - 50°, for example 45°. Optionally, at least one bulge is a dome-shaped bulge or all bulges are dome-shaped bulges. Optionally, the warp wires and/or the weft wires of the woven wire mesh extend at an angle relative to the longitudinal direction of the first section, e.g. at an angle of 30°- 60°, optionally at an angle of 40° - 50°, for example at an angle of 45°.

The invention will be described in more detail below under reference to the drawing, in which in a non-limiting manner exemplary embodiments of the invention will be shown. The drawing illustrates in:

Fig. 1 : schematically, an embodiment of a wire mesh premix burner according to the invention, in cross section,

Fig. 2: schematically, an example of a known non-cylindrical burner deck comprising a woven wire mesh,

Fig. 3: schematically, an example of the temperature regions of a non-cylindrical burner deck comprising a woven wire mesh when the burner deck is in use in a wire mesh premix burner,

Fig. 4: schematically, a first embodiment of a burner deck of a wire mesh premix burner according to the invention, in top view,

Fig. 4A: schematically, the cross sectional shape of the first section,

Fig. 4B: schematically, the cross sectional shape of the second section,

Fig. 5: schematically, a first variant of the embodiment of fig. 4,

Fig. 6: schematically, a second variant of the embodiment of fig. 4,

Fig. 7: schematically, a second embodiment of a burner deck of a wire mesh premix burner according to the invention, in top view,

Fig. 8: schematically, a variant of the second embodiment as shown in fig. 7,

Fig. 9: schematically, a third embodiment of a burner deck of a wire mesh premix burner according to the invention, in top view.

Fig. 1 shows schematically, an embodiment of a wire mesh premix burner 1 according to the invention, in cross section.

In this embodiment, the wire mesh premix burner 1 further comprises a non-cylindrical burner deck 10, a housing 2 and a gas distribution chamber 3. The gas distribution chamber 3 is accommodated in the housing 2.

The burner deck 10 comprises a woven wire mesh 20 having warp wires and weft wires. Between adjacent warp wires and adjacent weft wires, gas outflow openings are present. Premix gas, which is a mixture of air and fuel gas, is fed to the gas distribution chamber through gas inlet 4. The fuel gas is for example natural gas, hydrogen or a mix of natural gas an hydrogen. Premix gas is for example obtained by feeding air and fuel gas into a common feed tube and mixing the air and the fuel gas e.g. by a fan and/or a venturi. This premix gas is than fed to the gas inlet 4.

The gas distribution chamber 3 is in fluid communication with the burner deck 10. This allows premix gas to flow from the gas distribution chamber 4 to the burner deck and through the gas outflow openings of the woven wire mesh 20 of the burner deck 10.

The premix gas is ignited to generate a flame on the side of the burner deck 10 that faces away from the gas distribution chamber 3. The heat that is thus generated can for example be used to heat a heating medium such as water in a heating system.

Optionally, in this embodiment a gas diffuser 5 is provided. The gas diffuser 5 is in this embodiment arranged between the gas distribution chamber 3 and the burner deck 10. The gas diffuser 5 distributes the premix gas over the burner deck 10, in particular over the woven wire mesh 20 of the burner deck 10. In this embodiment, the gas diffuser 5 does not provide structural support to the woven wire mesh 20 as the gas diffuser 5 does not touch the woven wire mesh 20. The gas diffuser 5 may for example be flat, curved, double curved. Optionally, the gas diffuser 5 comprises one or more bulges.

In the embodiment of fig. 1 , the woven wire mesh 20 is arranged onto the housing 2 in a floating manner, i.e. the woven wire mesh 20 can expand freely relative to the housing 2 in at least one direction. In the embodiment of fig. 1, this is the horizontal direction left-right in fig. 1. Optionally, the woven wire mesh 20 can also expand freely in the horizontal direction perpendicular to the direction shown in fig. 1. Preferably, the woven wire mesh 20 is arranged onto the housing 2 in a floating manner such that the woven wire mesh can expand freely in the plane of the drawing of fig. 1 , in particular in the direction of the warp wires and/or the weft wires in as far as the warp wires and weft wires extend in the plane of the drawing of fig. 1 , and/or at an angle relative to the warp wires and/or the weft wires in this plane, e.g. an angle of 30° - 60 °, for example of 40 °- 50 °, e.g. 45°.

Fig.2 schematically shows an example of a known non-cylindrical burner deck 10 comprising a woven wire mesh 20. In this example, the burner deck 10 has a rectangular shape, optionally with rounded corners.

The burner deck 10 of fig. 2 may be flat, but alternatively it may be curved or double curved.

The woven wire mesh 20 comprises warp wires 21 and weft wires 22 which extend perpendicular to each other. In fig. 2, the warp wires 21 are represented by the horizontal lines in the woven wire mesh 20 and the weft wires 22 are represented by the vertical lines in the woven wire mesh 20.

The woven wire mesh 20 has gas outflow openings 23 which are delimited by adjacent warp wires 21 and adjacent weft wires 22. The gas outflow openings are represented by the small white squares between adjacent warp wires 21 and adjacent weft wires 22 in the woven wire mesh 20 of fig. 2.

In the example of fig. 2, the warp wires 21 extend parallel to two opposing edges of the woven wire mesh 20, and the weft wires extend parallel to the other two opposing edges of the woven wire mesh 20. Alternatively, the warp wires 21 and he weft wires 22 may extend at an angle of 45° relative to the edges of the woven wire mesh, or at an angle of 40°- 50 , or at an angle of 30°- 60°, or at any other angle. This is shown in fig. 2A.

Fig. 3 shows schematically an example of the temperature regions of a non-cylindrical burner deck comprising a woven wire mesh when the burner deck is in use in a wire mesh premix burner. In this example, the burner deck 10 is rectangular. The burner deck 10 that is shown in fig. 3 can be a known burner deck or a burner deck according to the invention.

In use, the burner deck 10 has a high temperature region 11 which is at a high temperature. The temperature can be for example a temperature in the range of 500°C - 900°C. The temperature in the high temperature generally shows little or no local variations. Often, the high-temperature region 11 is located centrally on the burner deck 10. In the embodiment of fig. 3, the burner deck 10 has a rectangular shape, and also the high- temperature region 11 has a rectangular shape.

The edges 14, 15, 16, 17 of the burner deck 10 are significantly cooler than the high temperature region 11 of the burner deck 10. They may have for example a temperature below 150°C. Optionally, a low temperature region 13 is present adjacent to the edges 14, 15, 16, 17. In this low temperature region 13, the temperature shows little or no local variations.

Between the high temperature region 11 and the cool edges 14, 15, 16, 17, a temperature gradient region 12 is present. This temperature gradient region 12 forms the transition between the high temperature region 11 and the cool edges 14, 15, 16, 17 or the transition between the high temperature region 11 and the low temperature region 13 is a cool temperature region 13 is present. So, the temperature gradient region 12 is located adjacent to the high temperature region 11 of the burner deck 10.

The high temperature region 11 and the temperature gradient region 12 can be identified by thermal imaging when the wire mesh premix burner 1 is in use, or by calculations on a finite element model of the woven wire mesh 20. In the burner deck 10 of fig. 3, the woven wire mesh 20 comprises a primary portion 24 which forms the high temperature region 11 of the burner deck 10. The woven wire mesh 20 further comprises a secondary portion 25 which forms the temperature gradient region 12 of the burner deck 10. Optionally, and shown in the example of fig. 3, the woven wire mesh 20 further comprises a tertiary region 26, which forms a low temperature region 13 of the burner deck 11 , adjacent to the secondary portion 25 of the woven wire mesh 20.

In the example of fig. 3, the primary portion 24 has a rectangular shape. In this example, the secondary portion 25 extends around the circumference of the primary portion 24, in this example around the entire circumference of the primary portion 24.

In this example, the primary portion 24 is present in the center of the woven wire mesh 20, and the secondary portion 25 extends around the circumference of the primary portion 24, in this example around the entire circumference of the primary portion 24.

Fig. 4 schematically shows a first embodiment of a burner deck of a wire mesh premix burner according to the invention, in top view.

In this embodiment, the burner deck 10 has a high temperature region 11 in the center of the burner deck 10. In use, the edges 14, 15, 16, 17 of the burner deck 10 are significantly cooler than the high temperature region 11. Between the high temperature region 11 and the edges 14, 15, 16, 17, a temperature gradient region 12 is present which forms the transition between the high temperature region 11 and the relatively cool edges 14, 15, 16, 17. Optionally, a low temperature region 13 is present between the temperature gradient region 12 and an edge 14, 15, 16, 17 of the burner deck 10.

The high temperature region 11 and the temperature gradient region 12 can be identified by thermal imaging when the wire mesh premix burner is in use, or by calculations on a finite element model of the woven wire mesh 20.

In the embodiment of fig. 4, the burner deck 10 comprises a woven wire mesh 20. The woven wire mesh comprises warp wires and weft wires which extend perpendicular to each other. The woven wire mesh has gas outflow openings which are delimited by adjacent warp wires and adjacent weft wires. In use, premix gas flows though these outflow openings to the free surface, out of the wire mesh premix burner. This premix gas is ignited to form a flame on the free surface of the burner deck, which flame is fed by a continuing flow of premix gas through the outflow openings of the woven wire mesh of the burner deck.

The warp wires, weft wires and outflow openings are not shown in fig. 4 in order to keep fig. 4 as clear as possible. However, the warp wires, weft wires and gas outflow openings may for example be as is shown in fig. 2 or fig. 2A and/or described in relation to fig. 2 or fig.

2A.

In the embodiment of fig. 4, the woven wire mesh 20 comprises a primary portion 24 which forms the high temperature region 11 of the burner deck 10. The woven wire mesh 20 further comprises a secondary portion 25 which forms the temperature gradient region 12 of the burner deck 10.

In the embodiment of fig. 4, the primary portion 24 has a rectangular shape. The secondary portion 25 extends around the circumference of the primary portion 24.

In the embodiment of fig. 4, the primary portion 24 is present in the center of the woven wire mesh 20, and the secondary portion extends 25 around the circumference of the primary portion 24.

In the embodiment of fig. 4, optionally, the woven wire mesh 20 further comprises a tertiary region 26, which forms a low temperature region 13 of the burner deck 10, adjacent to the secondary portion 25 of the woven wire mesh 20.

The secondary portion 25 of the woven wire mesh 20 has a first section 31. The first section 31 has a longitudinal direction. The first section 31 in this embodiment has a rectangular shape. The secondary portion 25 also comprises a second section 32. The second section 32 also has a longitudinal direction. The second section 32 in this embodiment has a rectangular shape too. The longitudinal direction of the second section 32 extends perpendicular to the longitudinal direction of the first section 31.

In the embodiment of fig. 4, the width of the first section 31, measured perpendicular to the longitudinal direction of the first section 31, is 35% or less of the width of the primary portion 24 measured in the same direction. Likewise, the width of the second section 32, measured perpendicular to the longitudinal direction of the second section 32, is 35% or less of the width of the primary portion 24 measured in the same direction.

In the embodiment of fig. 4, the longitudinal direction of the first section 31 extends parallel to the edge 14 of the burner deck 10 which is adjacent to the first section 31. In addition, the longitudinal direction of the second section 32 extends parallel to the edge 15 of burner deck 10 which is adjacent to the second section 32. In the embodiment of fig. 4, the edges of the burner deck 10 coincide with the edges of the woven wire mesh 20.

In the embodiment of fig. 4, the first section 31 of the secondary portion 25 comprises a plurality of bulges 35. These bulges 35 have a cross sectional shape in a first direction in the form of a wave. The cross sectional shape can be a single wave or multiple waves. The first direction is in this embodiment parallel to the longitudinal direction of the first section 31, and to an edge 14 of the burner deck 10, which is adjacent to the first section 31. Fig. 4A shows the cross sectional shape of the first section 31.

In the embodiment of fig. 4, the second section 32 of the secondary portion 25 also comprises a plurality of bulges 35. These bulges 35 have a cross sectional shape in a second direction in the form of a wave, wherein the second direction is perpendicular to the first direction. The cross sectional shape can be a single wave or multiple waves. The second direction is in this embodiment parallel to the longitudinal direction of the second section 32, and to the edge 15 of the burner deck 10, which is adjacent to the second section 32. Fig. 4B shows the cross sectional shape of the second section 32.

In the embodiment of fig. 4, the first direction is parallel to the longitudinal direction of the first section 31 and the second direction is parallel to the longitudinal direction of the second section 32. In addition, the first direction is parallel to the edge 14 of the burner deck 10 adjacent to the first section 31 and the second direction is parallel to the edge 15 of the burner deck 10 adjacent to the second section 32.

In the embodiment of fig. 4, the secondary portion 25 of the woven wire mesh 20 further comprises a third section 33, which is located opposite to the first section 31. The third section 33 has a longitudinal direction and a rectangular shape. The third section 33 comprises a plurality of bulges 35, which bulges 35 have a cross sectional shape in the first direction in the form of a wave.

In addition, in this embodiment the secondary portion 25 of the woven wire mesh 20 further comprises a fourth section 34, which is located opposite to the second section 32. The fourth section 34 has a longitudinal direction and a rectangular shape. The fourth section 34 comprises a plurality of bulges 35, which bulges 35 have a cross sectional shape in the second direction in the form of a wave.

In the embodiment of fig. 4, the longitudinal direction the first section 31 and the longitudinal direction of the third section 33 are parallel to each other. In addition, the longitudinal direction the second section 32 and the longitudinal direction of the fourth section 34 are parallel to each other.

In the embodiment of fig. 4, the longitudinal direction of the third section 33 and the first direction are parallel to each other.

In the embodiment of fig. 4, the longitudinal direction of the fourth section 34 and the second direction are parallel to each other.

In the embodiment of fig. 4, the secondary portion 25 of the woven wire mesh 20 has a rectangular shape having four sides, and the first section 31 is located on a first side of the rectangular shape, the second section 32 is located on the second side of the rectangular shape (the second side of the rectangular shape being perpendicular to the first side of the rectangular shape), the third section 33 is located on the third side of the rectangular shape (the third side of the rectangular shape being parallel to the first side of the rectangular shape) and the fourth section 34 is arranged on the fourth side of the rectangular shape (the fourth side of the rectangular shape being parallel to the second side of the rectangular shape).

In the embodiment of fig. 4, the bulges 35 in the first section 31 of the secondary portion 25 of the woven wire mesh 20 have an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the first section 31. The longitudinal axes of the bulges 35 in the first section 31 extend parallel to each other.

In addition, the bulges 35 in the second section 32 of the secondary portion 25 of the woven wire mesh 20 have an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the second section 32. The longitudinal axes of the bulges 35 in the second section 32 extend parallel to each other.

Furthermore, the bulges 35 in the third section 33 of the secondary portion 25 of the woven wire mesh 20 have an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the third section 33. The longitudinal axes of the bulges 35 in the third section 33 extend parallel to each other.

In addition, the bulges 35 in the fourth section 34 of the secondary portion 25 of the woven wire mesh 20 have an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the fourth section 34. The longitudinal axes of the bulges 35 in the fourth section 34 extend parallel to each other.

Optionally, as shown in the embodiment of fig. 4, the bulges 35 extend into the primary portion as well as into the tertiary portion of the woven wire mesh. Alternatively, the bulges are present only in the secondary portion, or extend from the secondary portion into the primary portion only, or extend from the secondary portion into the tertiary portion only.

In the example of fig. 4, the bulges optionally extend all the way up to the edges of the woven wire mesh.

Optionally, in the embodiment of fig. 4, the cross sectional shape of the bulges 35 in the first section 31 and/or in the second section 32 and/or in the third section 33 and/or in the fourth section 34 is a smooth wave (i.e. a wave not having sharp corners), e.g. a sine wave or a parabolic wave. The bulges 35 in the first section 31, in the second section 32, in the third section 33 and in the fourth section 34 are formed by the woven wire mesh 20. Optionally, at least one bulge is self-supporting.

Optionally, the woven wire mesh 20 is self-supporting, i.e. the woven wire mesh 20 is only supported at its edges.

Optionally, at least the primary portion 24 of the woven wire mesh 20 is self-supporting, i.e. the primary portion 20 of the woven wire mesh 20 does not directly contact a support of the woven wire mesh 20.

In the embodiment of fig. 4, the primary portion 24 of the woven wire mesh 20 extends in a flat plane, or in a curved plane, or in a double curved plane.

In the embodiment of fig. 4, the bulges 35 extend somewhat into the primary portion 24 of the woven wire mesh 20. There are no bulges which are entirely arranged within the primary portion 24 of the woven wire mesh 20. So, the only bulges 35 that are present in the primary portion 24 of the woven wire mesh 20, are those that extend into the secondary portion 25 of the woven wire mesh 20 as well.

Optionally, the bulges 35 extend all the way to the edges of the burner deck. Optionally, the local height of a bulge 35 at the edge of the burner deck is the same or substantially the same as the local height of that same bulge 35 at its centre (as seen in longitudinal direction of the bulge).

In the embodiment of fig. 4, the warp wires or the weft wires of the woven wire mesh 20 may extend at an angle relative to the longitudinal direction of the first section 31, e.g. at an angle of 30°- 60°, optionally at an angle of 40° - 50°, for example at an angle of 45°.

Alternatively, the warp wires or the weft wires of the woven wire mesh 20 extend parallel to the longitudinal direction of the first section 31 , and the other one of the warp wires or the weft wires of the woven wire mesh 20 extend parallel to the longitudinal direction of the second section 32.

Fig. 5 schematically shows a variant of the embodiment of fig. 4.

The variant of fig. 5 has all features of the embodiment of fig. 4. In addition, in this variant the woven wire mesh 20 comprises four vertex bulges 36. Each of the vertex bulges 36 has a longitudinal axis. A first vertex bulge 36 is arranged at a transition area between the first section 31 and the second section 32 of the secondary portion of the woven wire mesh 20. The longitudinal axis of the first vertex bulge extends at an angle of 45° relative to the longitudinal direction of the first section 31.

A second vertex bulge 36 is arranged at a transition area between the second section 32 and the third section 33 of the secondary portion of the woven wire mesh 20. The longitudinal axis of the second vertex bulge 36 extends at an angle of 45°, relative to the longitudinal direction of the second section 32.

A third vertex bulge 36 is arranged at a transition area between the third section 33 and the fourth section 34 of the secondary portion of the woven wire mesh 20. The longitudinal axis of the third vertex bulge 36 extends at an angle of 45° relative to the longitudinal direction of the third section 33.

A fourth vertex bulge 36 is arranged at a transition area between the fourth section 34 and the first section 31 of the secondary portion of the woven wire mesh 20. The longitudinal axis of the fourth vertex bulge 36 extends at an angle of 45° relative to the longitudinal direction of the fourth section 34.

In the variant of fig 5, the secondary portion 25 of the woven wire mesh 20 has a rectangular shape, and the first section 31 is present on one side of the rectangular shape of the secondary portion 25, and the second section 32 is present on the a second side of the rectangular shape, which second side extends perpendicular to the first side, and the transition area encompasses the corner of the rectangular shape between the first side and the second side of the rectangular shape. In this variant, the first vertex bulge 36 is located at the corner of the rectangular shape between the first side and the second side of the rectangular shape and the longitudinal axis of the first vertex bulge 36 extends at an angle of for example 45° relative to the longitudinal direction of the first section. Alternatively, other angles are possible. The vertex bulge 36 optionally points to the centre of the primary portion and/or to the centre of the woven mesh and/or to the centre of the burner deck. This is however not necessary.

Likewise, the third section 33 is present on a third side of the rectangle which extends perpendicular to the adjacent second side of the rectangular shape of the secondary portion 25, and the fourth section 34 is present on a fourth side of the rectangular shape of the secondary portion 25 which extends perpendicular to the third second side of the rectangle.

The transition area between the second side and the third side of the rectangular shape of the secondary portion 25 encompasses the corner of the rectangular shape between the second side and the third side of the rectangular shape. The second vertex bulge 36 is located at the corner of the rectangular shape between the second side and the third side of the rectangular shape and the longitudinal axis of the second vertex bulge 36 extends for example at an angle of 45° relative to the longitudinal direction of the second section. Alternatively, other angles are possible. The vertex bulge 36 optionally points to the centre of the primary portion and/or to the centre of the woven mesh and/or to the centre of the burner deck. This is however not necessary.

The transition area between the third side and the fourth side of the rectangular shape of the secondary portion 25 encompasses the corner of the rectangular shape between the third side and the fourth side of the rectangular shape. The third vertex bulge 36 is located at the corner of the rectangular shape between the third side and the fourth side of the rectangular shape and the longitudinal axis of the third vertex bulge 36 extends for example at an angle of 45° relative to the longitudinal direction of the third section. Alternatively, other angles are possible. The vertex bulge 36 optionally points to the centre of the primary portion and/or to the centre of the woven mesh and/or to the centre of the burner deck. This is however not necessary.

The transition area between the fourth side and the first side of the rectangular shape of the secondary portion 25 encompasses the corner of the rectangular shape between the fourth side and the first side of the rectangular shape. The fourth vertex bulge 36 is located at the corner of the rectangular shape between the fourth side and the first side of the rectangular shape and the longitudinal axis of the fourth vertex bulge 36 extends for example at an angle of 45° relative to the longitudinal direction of the fourth section. Alternatively, other angles are possible. The vertex bulge 36 optionally points to the centre of the primary portion and/or to the centre of the woven mesh and/or to the centre of the burner deck. This is however not necessary.

Optionally, the bulges 35, 36 extend all the way to the edges of the burner deck. Optionally, the local height of a bulge 35, 36 at the edge of the burner deck is the same or substantially the same as the local height of that same bulge 35, 36 at its centre (as seen in longitudinal direction of the bulge).

Fig. 6 shows a second variant of the embodiment of fig. 4. The variant of fig. 6 has all features of the embodiment of fig. 4. In addition, in this variant, like in the variant of fig. 5, the woven wire mesh 20 comprises four vertex bulges 36. Each of the vertex bulges 36 has a longitudinal axis.

In the variant of fig. 6, the burner deck 10 is mounted in a frame 40. The burner deck does not comprise a low temperature region, instead the temperature gradient region 12 extends up to the edges of the burner deck 10. In this embodiment, the burner deck 10 extends in a generally double curved plane. The bulges 35, 36 protrude from this double curved plane.

Fig. 7 schematically shows a second embodiment of a burner deck of a wire mesh premix burner according to the invention, in top view.

In this embodiment, the burner deck 10 has a high temperature region 11 in the center of the burner deck 10. In use, the edges 14, 15, 16, 17 of the burner deck 10 are significantly cooler than the high temperature region 11. Between the high temperature region 11 and the edges 14, 15, 16, 17, a temperature gradient region 12 is present which forms the transition between the high temperature region 11 and the relatively cool edges 14, 15, 16, 17. Optionally, a low temperature region is present between the temperature gradient region 12 and an edge 14, 15, 16, 17 of the burner deck 10.

In the embodiment of fig. 7, the burner deck 10 comprises a woven wire mesh 20. The woven wire mesh comprises warp wires and weft wires which extend perpendicular to each other. The woven wire mesh has gas outflow openings which are delimited by adjacent warp wires and adjacent weft wires. In use, premix gas flows though these outflow openings to the free surface, out of the wire mesh premix burner. This premix gas is ignited to form a flame on the free surface of the burner deck, which flame is fed by a continuing flow of premix gas through the outflow openings of the woven wire mesh of the burner deck.

The warp wires, weft wires and outflow openings are not shown in fig. 7 in order to keep fig. 7 as clear as possible. However, the warp wires, weft wires and gas outflow openings may for example be as is shown in fig. 2 or fig. 2A and/or described in relation to fig. 2 or fig.2A.

In the embodiment of fig. 7, the woven wire mesh 20 comprises a primary portion 24 which forms the high temperature region 11 of the burner deck 10. The woven wire mesh 20 further comprises a secondary portion 25 which forms the temperature gradient region 12 of the burner deck 10. In the embodiment of fig. 7, the primary portion 24 has a rectangular shape. The secondary portion 25 extends around the circumference of the primary portion 24.

In the embodiment of fig. 7, the primary portion 24 is present in the center of the woven wire mesh 20, and the secondary portion extends 25 around the circumference of the primary portion 24.

In the embodiment of fig. 7, optionally, the woven wire mesh 20 further comprises a tertiary region 26, which forms a low temperature region 13 of the burner deck 10, adjacent to the secondary portion 25 of the woven wire mesh 20.

In the embodiment of fig. 7, the width of the first section 31, measured perpendicular to the longitudinal direction of the first section 31, is 35% or less of the width of the primary portion 24 measured in the same direction. Likewise, the width of the second section 32, measured perpendicular to the longitudinal direction of the second section 32, is 35% or less of the width of the primary portion 24 measured in the same direction.

In the embodiment of fig. 7, the longitudinal direction of the first section 31 extends parallel to the edge 14 of the burner deck 10, which is adjacent to the first section 31. In addition, the longitudinal direction of the second section 32 extends parallel to the edge 15 of burner deck 10, which is adjacent to the second section 32. In the embodiment of fig. 7, the edges of the burner deck 10 coincide with the edges of the woven wire mesh 20.

In the embodiment of fig. 7, the first section 31 of the secondary portion 25 comprises a plurality of bulges 35 (in fig. 7 only one bulge is provided with a reference numeral 35 for reasons of keeping the figure as clear as possible, but all the circles in fig. 7 indicate the top of a bulge 35). These bulges 35 have a cross sectional shape in a first direction in the form of a wave. The cross sectional shape can be a single wave or multiple waves. The first direction is in this embodiment parallel to the longitudinal direction of the first section 31, and to an edge 14 of the burner deck 10, which is adjacent to the first section 31. Fig. 7A shows the cross sectional shape of the first section 31.

Alternatively, the first direction is optionally at an angle relative to the longitudinal direction of the first section 31 , e.g. at an angle of 30° - 60°, e.g. 40°- 50 e.g. 45°, and/or to the edge 14 of the burner deck 10 adjacent to the first section 31. In the embodiment of fig. 7, the bulges 35 in the first section 31 also have a cross sectional shape in a direction perpendicular to the first direction (i.e. in the second direction) in the form of a wave.

So, in this embodiment, the first section 31 comprises bulges 35 which have a cross sectional shape in the form of a wave when the cross section is taken in the first direction and also when the cross section is taken in the second direction. This results for example in dome-shaped bulges. Fig. 7A shows the cross section of the first section 31 in the first direction, with a succession of wave-shaped bulges 35. Fig. 7B shows a cross section of a bulge 35 of the first section 31 in the second direction.

In the embodiment of fig. 7, the second section 32 of the secondary portion 25 also comprises a plurality of bulges 35. These bulges 35 have a cross sectional shape in a second direction in the form of a wave, wherein the second direction is perpendicular to the first direction. The cross sectional shape can be a single wave or multiple waves. The second direction is in this embodiment parallel to the longitudinal direction of the second section 32, and to the edge 15 of the burner deck 10, which is adjacent to the second section 32. Fig. 7C shows the cross sectional shape of the second section 32.

In the embodiment of fig. 7, the first direction is parallel to the longitudinal direction of the first section 31 and the second direction is parallel to the longitudinal direction of the second section 32. In addition, the first direction is parallel to the edge 14 of the burner deck 10 adjacent to the first section 31 and the second direction is parallel to the edge 15 of the burner deck 10 adjacent to the second section 32.

In the embodiment of fig. 7, the second section 32 comprises bulges 35 which have also a cross sectional shape in a direction perpendicular to the second direction (i.e. in the first direction) in the form of a wave. So, in this case, the second section 32 comprises bulges which have a cross sectional shape in the form of a wave when the cross section is taken in the first direction and also when the cross section is taken in the second direction. This results for example in dome-shaped bulges.

Fig. 7C shows the cross section of the second section 32 in the second direction, with a succession of wave-shaped bulges 35. Fig. 7D shows a cross section of a bulge 35 of the second section 32 in the first direction, which is perpendicular to the second direction.

In the embodiment of fig. 7, the secondary portion 25 of the woven wire mesh 20 further comprises a third section 33, which is located opposite to the first section 31. The third section 33 has a longitudinal direction and a rectangular shape. The third section 33 comprises a plurality of bulges 35, which bulges 35 have a cross sectional shape in the first direction in the form of a wave. In the embodiment of fig. 7, the bulges 35 the third section 33 also have a cross sectional shape in a direction perpendicular to the first direction (i.e. in the second direction) in the form of a wave. So, in this embodiment, the third section 33 comprises bulges 35 which have a cross sectional shape in the form of a wave when the cross section is taken in the first direction and also when the cross section is taken in the second direction. This results for example in dome-shaped bulges.

In the embodiment of fig. 7, the fourth section 34 comprises bulges 35 which have also a cross sectional shape in a direction perpendicular to the second direction (i.e. in the first direction) in the form of a wave. So, in this case, the fourth section 34 comprises bulges which have a cross sectional shape in the form of a wave when the cross section is taken in the first direction and also when the cross section is taken in the second direction. This results for example in dome-shaped bulges.

In the embodiment of fig. 7, the secondary portion 25 of the woven wire mesh 20 has a rectangular shape having four sides, and the first section 31 is located on a first side of the rectangular shape, the second section 32 is located on the second side of the rectangular shape (the second side of the rectangular shape being perpendicular to the first side of the rectangular shape), the third section 33 is located on the third side of the rectangular shape (the third side of the rectangular shape being parallel to the first side of the rectangular shape) and the fourth section 34 is arranged on the fourth side of the rectangular shape (the fourth side of the rectangular shape being parallel to the second side of the rectangular shape).

Optionally, in the embodiment of fig. 7, the cross sectional shape of the bulges 35 in the first section 31 and/or in the second section 32 and/or in the third section 33 and/or in the fourth section 34 is a smooth wave (i.e. a wave not having sharp corners), e.g. a sine wave or a parabolic wave or a spline or a catenary.

In the embodiment of fig. 7, the primary portion 24 of the woven wire mesh 20 extends in a flat plane, or in a curved plane, or in a double curved plane. In the embodiment of fig. 7, the primary portion of the woven wire mesh comprises a plurality of bulges 35 and the bulges 35 in the primary portion 24 of the woven wire mesh extend from a flat, curved or double curved plane.

The bulges 35 in the primary portion 24 of the woven wire mesh 20 have a cross sectional shape in the first direction in the form of a wave and a cross sectional shape in the second direction in the form of a wave. This results for example in dome-shaped bulges.

In the embodiment of fig. 7, an array 37 of bulges 35 is present in the primary portion 24 of the woven wire mesh 20. The array 37 of bulges 35 extends along a line which is perpendicular to the longitudinal direction of the first section. In fig. 7 can be seen that there are also arrays of bulges 35 which extend along a line which is parallel to the longitudinal direction of the first section. Alternatively, one or more arrays of bulges 35 can extend along a line which is at an angle relative to the longitudinal direction of the first section, e.g. an angle of 30°- 60°, optionally at an angle of 40°- 50°, for example at an angle of 45°.

In the embodiment of fig. 7, the plurality of bulges 35 in the primary portion 24 of the woven wire mesh 20 is arranged in a rectangular grid which has a first main direction and a second main direction which is perpendicular to the first main direction.

In this embodiment, the first main direction is parallel to the longitudinal direction of the first section, and the second main direction extends or perpendicular to the longitudinal direction of the first section. Alternatively, the first main direction of the grid extends at an angle relative to the longitudinal direction of the first section, which angle is for example 30°- 60° relative to the longitudinal direction of the first section, optionally 40° - 50°, for example 45°.

The bulges 35 in the first section 31 , in the second section 32, in the third section 33 and in the fourth section 34 are formed by the woven wire mesh 20. Optionally, at least one bulge is self-supporting.

Optionally, at least the primary portion 24 of the woven wire mesh 20 is self-supporting, i.e. the primary portion 20 of the woven wire mesh 20 does not directly contact a support of the woven wire mesh 20. In the embodiment of fig. 7, the warp wires or the weft wires of the woven wire mesh may extend at an angle relative to the longitudinal direction of the first section 31, e.g. an angle of 30°- 60°, optionally at an angle of 40° - 50°, for example at an angle of 45°.

Alternatively, the warp wires or the weft wires of the woven wire mesh extend parallel to the longitudinal direction of the first section 31 , and the other one of the warp wires or the weft wires of the woven wire mesh extend parallel to the longitudinal direction of the second section 32.

Fig. 8 shows a variant of the embodiment of fig. 7, which mainly differs from the embodiment of fig. 7 in the number of bulges 35.

In the embodiment of fig. 8, the burner deck 10 and therewith the woven wire mesh 20 as well, extends in a curved plane. The bulges 35 extend from this curved plane.

Fig. 9 schematically shows a third embodiment of a burner deck of a wire mesh premix burner according to the invention, in top view.

In the embodiment of fig. 9, the burner deck 10 comprises a woven wire mesh 20. The woven wire mesh comprises warp wires and weft wires which extend perpendicular to each other. The woven wire mesh has gas outflow openings which are delimited by adjacent warp wires and adjacent weft wires. In use, premix gas flows though these outflow openings to the free surface, out of the wire mesh premix burner. This premix gas is ignited to form a flame on the free surface of the burner deck, which flame is fed by a continuing flow of premix gas through the outflow openings of the woven wire mesh of the burner deck.

The warp wires, weft wires and outflow openings are not shown in fig. 9 in order to keep fig. 9 as clear as possible. However, the warp wires, weft wires and gas outflow openings may for example be as is shown in fig. 2 or fig. 2A and/or described in relation to fig. 2 or fig. 2A. In the embodiment of fig. 9, the woven wire mesh 20 comprises a primary portion 24 which forms the high temperature region 11 of the burner deck 10. The woven wire mesh 20 further comprises a secondary portion 25 which forms the temperature gradient region 12 of the burner deck 10.

In the embodiment of fig. 9, the primary portion 24 has a rectangular shape. The secondary portion 25 extends around the circumference of the primary portion 24.

In the embodiment of fig. 9, the primary portion 24 is present in the center of the woven wire mesh 20, and the secondary portion extends 25 around the circumference of the primary portion 24.

In the embodiment of fig. 9, optionally, the woven wire mesh 20 further comprises a tertiary region 26, which forms a low temperature region 13 of the burner deck 10, adjacent to the secondary portion 25 of the woven wire mesh 20.

The secondary portion 25 of the woven wire mesh 20 has a first section 31. The first section 31 has a longitudinal direction 31*. The first section 31 in this embodiment has a rectangular or elongated shape, with rounded side edges. In this embodiment the first section 31 coincides with a full side of the rectangular second portion 25, in this example the side adjacent to edge 16 of the burner deck 10.

The secondary portion 25 also comprises a second section 32. The second section 32 also has a longitudinal direction 32*. The second section 32 in this embodiment has a rectangular or elongated shape, with rounded side edges. In this embodiment the second section 32 coincides with a full side of the rectangular second portion 25, in this example the side adjacent to edge 15 of the burner deck 10.

The longitudinal direction of the second section 32 extends perpendicular to the longitudinal direction of the first section 31. In the embodiment of fig. 9, the first section 31 and the second section 32 overlap each other in the corner of the secondary portion 25 adjacent to the corner of the burner deck 10 between the edges 15 and 16.

In the embodiment of fig. 9, the bulges 35 are for example located at the position of the vertex bulges 36 of the embodiment of fig. 5 and fig. 6.

In the embodiment of fig. 9, the width of the first section 31, measured perpendicular to the longitudinal direction 31* of the first section 31 , is 35% or less of the width of the primary portion 24 measured in the same direction. Likewise, the width of the second section 32, measured perpendicular to the longitudinal direction 32* of the second section 32, is 35% or less of the width of the primary portion 24 measured in the same direction. In the embodiment of fig. 9, the longitudinal direction 31* of the first section 31 extends parallel to the edge 16 of the burner deck 10 which is adjacent to the first section 31. In addition, the longitudinal direction 32* of the second section 32 extends parallel to the edge 15 of burner deck 10 which is adjacent to the second section 32. In the embodiment of fig. 9, the edges of the burner deck 10 coincide with the edges of the woven wire mesh 20.

In the embodiment of fig. 9, the first section 31 of the secondary portion 25 comprises a plurality of bulges 35. These bulges 35 have a cross sectional shape in a first direction in the form of a wave. The cross sectional shape can be a single wave or multiple waves. The first direction is in this embodiment parallel to the longitudinal direction 31* of the first section 31, and to an edge 16 of the burner deck 10, which is adjacent to the first section 31. In this embodiment, the bulges 35 are located at the corners of the secondary portion 25.

In the embodiment of fig. 9, the second section 32 of the secondary portion 25 also comprises a plurality of bulges 35. These bulges 35 have a cross sectional shape in a second direction in the form of a wave, wherein the second direction is perpendicular to the first direction. The cross sectional shape can be a single wave or multiple waves. The second direction is in this embodiment parallel to the longitudinal direction 32* of the second section 32, and to the edge 15 of the burner deck 10, which is adjacent to the second section 32.

In the embodiment of fig. 9, the first direction is parallel to the longitudinal direction of the first section 31 and the second direction is parallel to the longitudinal direction of the second section 32. In addition, the first direction is parallel to the edge 16 of the burner deck 10 adjacent to the first section 31 and the second direction is parallel to the edge 15 of the burner deck 10 adjacent to the second section 32.

In the embodiment of fig. 9, the bulges 35 in the first section 31 of the secondary portion 25 of the woven wire mesh 20 have an elongated shape with a longitudinal axis which extends at an angle relative to the longitudinal direction 31* of the first section 31 , e.g. at an angle of 30° - 60 for example at an angle of 45°. The longitudinal axes of the bulges 35 in the first section 31 extend at an angle relative to each other.

In addition, the bulges 35 in the second section 32 of the secondary portion 25 of the woven wire mesh 20 have an elongated shape with a longitudinal axis which extends at an angle relative to the longitudinal direction 32* of the second section 32, e.g. at an angle of 30° - 60 for example at an angle of 45°. The longitudinal axes of the bulges 35 in the second section 32 extend at an angle relative to each other. In the embodiment of fig. 9, the secondary portion 25 of the woven wire mesh 20 further comprises a third section 33, which is located opposite to the first section 31. The third section 33 has a longitudinal direction 33*. The third section 33 in this embodiment has a rectangular or elongated shape, with rounded side edges. In this embodiment the third section 33 coincides with a full side of the rectangular second portion 25, in this example the side adjacent to edge 14 of the burner deck 10.

The longitudinal direction of the second section 32 extends perpendicular to the longitudinal direction of the third section 33. In the embodiment of fig. 9, the third section 33 and the second section 32 overlap each other in the corner of the secondary portion 25 adjacent to the corner of the burner deck 10 between the edges 14 and 15.

The third section 33 comprises a plurality of bulges 35, which bulges 35 have a cross sectional shape in the first direction in the form of a wave.

In the embodiment of fig. 9, the longitudinal direction the first section 31 and the longitudinal direction of the third section 33 are parallel to each other.

In the embodiment of fig. 9, the longitudinal direction 33* of the third section 33 and the first direction are parallel to each other.

In the embodiment of fig. 9, the secondary portion 25 of the woven wire mesh 20 has a rectangular shape having four sides, and the first section 31 is located on a first side of the rectangular shape, the second section 32 is located on the second side of the rectangular shape (the second side of the rectangular shape being perpendicular to the first side of the rectangular shape) and the third section 33 is located on the third side of the rectangular shape (the third side of the rectangular shape being parallel to the first side of the rectangular shape).

In the embodiment of fig. 9, the bulges 35 in the third section 33 of the secondary portion 25 of the woven wire mesh 20 have an elongated shape with a longitudinal axis which extends at an angle relative to the longitudinal direction 33* of the third section 33, e.g. at an angle of 30° - 60 for example at an angle of 45°. The longitudinal axes of the bulges 35 in the third section 33 extend at an angle relative to each other.

Optionally, as shown in the embodiment of fig. 9, the bulges 35 extend into the primary portion as well as into the tertiary portion of the woven wire mesh. Alternatively, the bulges are present only in the secondary portion, or extend from the secondary portion into the primary portion only, or extend from the secondary portion into the tertiary portion only. In the example of fig. 9, the bulges optionally extend all the way up to the edges and/or corners of the woven wire mesh.

Optionally, in the embodiment of fig. 9, the cross sectional shape of the bulges 35 in the first section 31 and/or in the second section 32 and/or in the third section 33 is a smooth wave (i.e. a wave not having sharp corners), e.g. a sine wave or a parabolic wave.

The bulges 35 in the first section 31, in the second section 32 and in the third section 33 are formed by the woven wire mesh 20. Optionally, at least one bulge is self-supporting.

In the embodiment of fig. 9, the primary portion 24 of the woven wire mesh 20 extends in a flat plane, or in a curved plane, or in a double curved plane.

In the embodiment of fig. 9, the bulges 35 extend somewhat into the primary portion 24 of the woven wire mesh 20. There are no bulges which are entirely arranged within the primary portion 24 of the woven wire mesh 20. So, the only bulges 35 that are present in the primary portion 24 of the woven wire mesh 20, are those that extend into the secondary portion 25 of the woven wire mesh 20 as well.

Optionally, the bulges 35 extend all the way to the edges and/or corners of the burner deck. Optionally, the local height of a bulge 35 at the edge and/or corner of the burner deck is the same or substantially the same as the local height of that same bulge 35 at its centre (as seen in longitudinal direction of the bulge).

In the embodiment of fig. 9, the warp wires or the weft wires of the woven wire mesh 20 may extend at an angle relative to the longitudinal direction of the first section 31, e.g. at an angle of 30°- 60°, optionally at an angle of 40° - 50°, for example at an angle of 45°.

Alternatively, the warp wires or the weft wires of the woven wire mesh 20 extend parallel to the longitudinal direction of the first section 31 , and the other one of the warp wires or the weft wires of the woven wire mesh 20 extend parallel to the longitudinal direction of the second section 32. Optionally, one or more additional bulges may be present in the secondary portion 25 of the woven wire mesh, e.g. between the bulges 35 shown in fig. 9.

5

Claims

C L A I M S

1. Wire mesh premix burner, comprising: a non-cylindrical burner deck, wherein the burner deck has a high temperature region and a temperature gradient region adjacent to the high temperature region, wherein the burner deck comprises a woven wire mesh, which woven wire mesh comprises warp wires and weft wires which extend perpendicular to each other, and which woven wire mesh has gas outflow openings which are delimited by adjacent warp wires and adjacent weft wires, wherein the woven wire mesh comprises a primary portion which forms the high temperature region of the burner deck and a secondary portion which forms the temperature gradient region of the burner deck, wherein the secondary portion of the woven wire mesh has a first section having a longitudinal direction and a second section also having a longitudinal direction, wherein the longitudinal direction of the second section extends perpendicular to the longitudinal direction of the first section, wherein the first section comprises a plurality of bulges, which bulges have a cross sectional shape in a first direction in the form of a wave, and wherein the second section comprises a plurality of bulges, which bulges have a cross sectional shape in a second direction in the form of a wave, wherein the second direction is perpendicular to the first direction.

2. Wire mesh premix burner according to claim 1 , wherein the secondary portion of the woven wire mesh further comprises a third section which is located opposite to the first section, which third section has a longitudinal direction, and wherein the third section comprises a plurality of bulges, which bulges have a cross sectional shape in the first direction in the form of a wave, and/or wherein the secondary portion of the woven wire mesh further comprises a fourth section which is located opposite to the second section, which fourth section has a longitudinal direction, and wherein the fourth section comprises a plurality of bulges, which bulges have a cross sectional shape in the second direction in the form of a wave.

3. Wire mesh premix burner according to any of the preceding claims, wherein a bulge in the first section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the first section.

4. Wire mesh premix burner according to claim 3, wherein a bulge in the second section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the second section.

5. Wire mesh premix burner according to claim 2, wherein a bulge in the first section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the first section, and wherein a bulge in the third section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the third section, and/or wherein a bulge in the second section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the second section, and wherein a bulge in the fourth section of the secondary portion of the woven wire mesh has an elongated shape with a longitudinal axis which extends perpendicular to the longitudinal axis of the fourth section.

6. Wire mesh premix burner according to any of the preceding claims, wherein the first section comprises a bulge which has also a cross sectional shape in a direction perpendicular to the first direction in the form of a wave.

7. Wire mesh premix burner according to claim 6, wherein the second section comprises a bulge which has also a cross sectional shape in a direction perpendicular to the second direction in the form of a wave.

8. Wire mesh premix burner according to any of the preceding claims, wherein the primary portion of the woven wire mesh extends in a flat plane, or in a curved plane, or in a double curved plane.

9. Wire mesh premix burner according to any of the preceding claims, wherein the primary portion of the woven wire mesh comprises a plurality of bulges.

10. Wire mesh premix burner according to claim 9, wherein the primary portion of the woven wire mesh comprises a bulge which has a cross sectional shape in the first direction in the form of a wave, and/or wherein the primary portion of the woven wire mesh comprises a bulge which has a cross sectional shape in the second direction in the form of a wave, and/or wherein the primary portion of the woven wire mesh comprises a bulge which has a cross sectional shape in the first direction in the form of a wave and a cross sectional shape in the second direction in the form of a wave.

11. Wire mesh premix burner according to any of claims 9 - 10, wherein an array of bulges is present in the primary portion of the woven wire mesh, which array of bulges extends along a line which is parallel to the longitudinal direction of the first section, or along a line which is at an angle relative to the longitudinal direction of the first section, for example at an angle of 30°- 60° relative to the longitudinal direction of the first section, optionally at an angle of 40°- 50°, for example at an angle of 45°.

12. Wire mesh premix burner according to any of claims 9 - 11 , wherein a plurality of bulges in the primary portion of the woven wire mesh is arranged in a rectangular grid which has a first main direction and a second main direction which is perpendicular to the first main direction, wherein the first main direction is parallel to the longitudinal direction of the first section, or perpendicular to the longitudinal direction of the first section, or extends at an angle relative to the longitudinal direction of the first section, which angle is for example 30°- 60° relative to the longitudinal direction of the first section, optionally 40° - 50°, for example 45°.

13. Wire mesh burner according to any of the preceding claims, wherein the woven wire mesh comprises a vertex bulge having a longitudinal axis, which vertex bulge is arranged at a transition area between the first section and the second section of the woven wire mesh, and wherein the longitudinal axis of the vertex extends at an angle relative to the longitudinal direction of the first section, for example an angle of 30° - 60°, e.g. an angle of 40° - 50°, for example 45°.

14. Wire mesh premix burner according to any of the claims 1 - 8, wherein the primary portion of the woven wire mesh is free of bulges.

15. Wire mesh premix burner according to any of the preceding claims, wherein the warp wires and/or the weft wires of the woven wire mesh extend at an angle relative to the longitudinal direction of the first section, e.g. at an angle of 30°- 60° relative to the longitudinal direction of the first section, optionally at an angle of 40° - 50°, for example at an angle of 45°.

16. Wire mesh premix burner according to any of the preceding claims, wherein the wire mesh premix burner further comprises a housing and a gas distribution chamber which is accommodated in the housing, which gas distribution chamber is in fluid communication with the burner deck, allowing premix gas to flow from the gas distribution chamber to the burner deck and through the gas outflow openings of the woven wire mesh of the burner deck.

17. Wire mesh premix burner according to claim 16, wherein the woven wire mesh is arranged onto the housing in a floating manner.

18. Heating system comprising a wire mesh premix burner according to any of the preceding claims.