WO2024068496A1

WO2024068496A1 - Premix gas burner deck plate

Info

Publication number: WO2024068496A1
Application number: PCT/EP2023/076317
Authority: WO
Inventors: Camillo Marino Josef Hogenbirk; Marc BUS; Mathieu VERHOOGT
Original assignee: Bekaert Combustion Technology B.V.
Priority date: 2022-09-26
Filing date: 2023-09-25
Publication date: 2024-04-04

Abstract

The invention pertains to a premix gas burner deck plate, comprises: - a gas passage area, and - a heat transfer area, wherein the premix gas burner deck plate has a first plate thickness in the gas passage area and a second plate thickness in the heat transfer area, which second plate thickness is larger than the first plate thickness, and wherein the premix gas burner deck plate comprises a gas outflow channel which is adapted to during use supply premix gas to a combustion zone, which gas outflow channel is arranged in the gas passage area and extends through the first plate thickness from the distribution chamber side of the premix gas burner deck plate to the combustion zone side of the premix gas burner deck plate, and wherein the premix gas burner deck plate is made of cast aluminium.

Description

Premix gas burner deck plate

The invention pertains to a premix gas burner deck plate, a premix gas burner comprising the premix gas burner deck plate, a heating appliance comprising the premix gas burner and a method for manufacturing the premix gas burner deck plate.

A premix gas burner deck plate in accordance with the invention is of the type that is used in premix gas burners for heating appliances such as heater systems for buildings or domestic hot water systems. Traditionally, such premix gas burners use a premix burner gas that contains for example methane mixed with air. Currently, in order to reduce carbon dioxide emissions, developments are going on to add hydrogen to the premix burner gas, or even to replace the methane by hydrogen entirely.

A hydrogen burner comprising a premix gas burner deck adapted for hydrogen containing fuel gases could replace known natural gas burners. Typical residential natural gas 24 kW burners use about 1500m³ of natural gas per year. If such a natural gas burner would be replaced by a hydrogen burner, a CO2 emission reduction of 4.9 tonnes per year is obtained. So, every 1 million of these residential natural gas burners replaced allow to obtain a CO2 emission reduction of 4.9Mtonnes per year. If gradually in Europe during a time span of 10 years 30 million households are converted from natural gas to hydrogen an annual emission reduction of almost 150Mtonnes CO2 can be achieved.

Hydrogen burners emit far less NOx than conventional natural gas burners, or oil burners. Typically, a reduction of 41 mg/kWh NOx emissions is obtained as compared to a methane burner, and even a reduction of 69 mg/kWh as compared to an oil burner. Replacing a natural gas fired residential boiler by a hydrogen fired residential boiler allows to obtain an NOx emission reduction of 0.51kg/year per boiler. In case 50% of the houses in the Netherlands would be converted from natural gas combustion to hydrogen combustion, this would allow to reduce the NOx-emissions with 2.05Mkg. This is almost 4% of yearly NOx emissions of the Netherlands.

In use, the premix gas burner deck plate deck of a known premix gas burner often reaches a high maximum temperature of at least 500°C, often even up to more than 800°C. High burner deck temperatures increase the risk of flashback, in particular if the fuel gas is or contains hydrogen, as the hot burner deck may ignite the premix gas inside the burner, upstream of the premix gas burner deck plate, which is highly undesirable from a safety point of view. In addition, the premix gas burner deck plates of the type to which the invention pertains are often used in modulating heater systems, in which the thermal load on the burner varies significantly during relatively short time spans. This causes changes in the burner deck temperature, and therewith the amount of thermal expansion and the magnitude of thermal stresses in the burner deck of the premix gas burner. These varying stresses are a major cause of thermal fatigue. Often, special designs are necessary to deal with the varying temperatures.

The invention aims to provide an improved premix gas burner deck plate, which has a reduced risk of flashback.

In a first aspect of the invention, this object is obtained by a premix gas burner deck plate, which premix gas burner deck plate has a distribution chamber side and a combustion zone side, which distribution chamber side and combustion zone side are located on opposite sides of the premix gas burner deck plate, which premix gas burner deck plate further comprises:

- a gas passage area, and

- a heat transfer area, wherein the premix gas burner deck plate has a first plate thickness in the gas passage area and a second plate thickness in the heat transfer area, which second plate thickness is larger than the first plate thickness, and wherein the premix gas burner deck plate comprises a gas outflow channel which is adapted to during use supply gas to a combustion zone, which gas outflow channel is arranged in the gas passage area and extends through the first plate thickness from the distribution chamber side of the premix gas burner deck plate to the combustion zone side of the premix gas burner deck plate, and wherein the premix gas burner deck plate is made of cast aluminium.

The premix gas burner deck plate according to the first aspect of the invention has a distribution chamber side and a combustion zone side, which distribution chamber side and combustion zone side are located on opposite sides of the premix gas burner deck plate. When the premix gas burner deck plate is arranged in a premix gas burner, the distribution chamber side of the premix gas burner deck plate faces towards a gas distribution chamber of the premix gas burner, so, in upstream direction of the flow of the premix gas. When the premix gas burner deck plate is arranged in a premix gas burner, the combustion zone side of the premix gas burner deck plate faces towards a combustion zone in which the actual combustion of the premix gas takes place, so, in downstream direction of the flow of the premix gas. The premix gas burner deck plate according to the first aspect of the invention comprises a gas passage area and a heat transfer area. Premix gas passes from the distribution chamber side of the premix gas burner deck plate to the combustion zone side of the premix gas burner deck plate via the gas passage area. The heat transfer area is designed for effective heat transfer, with the aim of avoiding high burner deck temperatures in the premix gas burner deck plate. So, as in use the premix gas burner deck plate heats up due to the nearby combustion of the premix fuel gas in the combustion zone, and the heat transfer area of the premix gas burner deck plate is designed to transfer heat away from the premix burner deck area effectively, in order to avoid high burner deck temperatures. For example, in embodiments of the invention the burner deck temperatures may be kept below 500°C, optionally below 400°C, e.g. below 300°C, for example even below 200°.

The premix gas burner deck plate has a first plate thickness in the gas passage area and a second plate thickness in the heat transfer area. The second plate thickness is larger than the first plate thickness. For example, the first plate thickness is 0.5 millimeters (mm) up to and including 1.5 millimeters (mm), for example 1 millimeter (mm). For example, the second plate thickness is 1.5 millimeters (mm) to 10 millimeters (mm), e.g. 2 milimeters (mm) up to and including 7 millimeters (mm), for example 2.5 millimeters (mm) to 6 millimeters (mm), e.g. 5 millimeters (mm) or 3 millimeters (mm). For example, the first thickness is 1 mm and the second plate thickness is 3 mm. Of course, in case the first thickness is 1.5 mm, the second plate thickness is more than 1.5 mm.

Optionally, the second plate thickness varies over the heat transfer area, so different parts of the heat transfer area have a different thickness. This allows to tune the temperature distribution over the premix gas burner deck plate that occurs e.g. during use, and/or the distribution of the material stresses (e.g. with respect to the size and/or direction of these stresses) over the premix gas burner deck plate that occurs e.g. during use. For example, the second plate thickness in the middle of the premix gas burner deck plate is smaller than the second plate thickness closer to the edge of the premix gas burner deck plate. This may lead to a more effective heat transfer away from the gas passage areas and/or result in a more even temperature distribution over the premix gas burner deck plate. For example, when the heat is to be transferred away from the premix gas burner deck plate via the edges of the metal premix gas burner deck plate, more heat may need to be transferred via portions of the premix gas burner deck plate closer to the edges than via portions of the premix gas burner deck plate closer to the center of the premix gas burner deck plate. A larger thickness closer to the edges of the premix gas burner deck plate than in the center (or closer to the center) assists in a more effective heat transfer. Optionally, the premix gas burner deck plate or a part thereof (e.g. the heat transfer area or a part thereof) has cross-sectional shape which is or comprises a concave shape. The premix gas burner deck plate comprises a gas outflow channel which is adapted to during use supply premix gas to the combustion zone, in which combustion zone the combustion of the premix gas takes place during use of the premix gas burner deck plate in a premix gas burner. The combustion zone is usually present adjacent to but just outside of the premix gas burner in which the premix gas burner deck plate is arranged. The gas outflow channel is arranged in the gas passage area and extends through the first plate thickness from the distribution chamber side of the premix gas burner deck plate to the combustion zone side of the premix gas burner deck plate.

For example, the gas outflow channel has a circular cross-sectional shape, with a diameter that is either constant or varies over the length of the gas outflow channel. In case the diameter varies over the length of the gas outflow channel, the gas outflow channel is for example tapered. The taper angle of the gas outflow channel is optionally at least 6°, for example at least 9°, optionally at least 12°. The diameter at an end of the gas outflow channel, e.g. at the end with the smallest diameter, is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm. In case the diameter is constant over the length of the gas outflow channel, the diameter at an end of the gas outflow channel is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm.

Optionally, the gas outflow channel comprises a first channel portion which extends over a part of the length of said gas outflow channel, and this first channel portion is tapered. Optionally, the gas outflow channel further comprises a second channel portion which extends over a part of the length of said gas outflow channel, which second channel portion of said gas outflow channel has a constant diameter. Optionally the first channel portion and the second channel portion together form the gas outflow channel. The taper angle of the first channel portion is optionally at least 6°, for example at least 9°, optionally at least 12°. The diameter at an end of the first channel portion, e.g. at the end with the smallest diameter, is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm. The diameter of the second channel portion is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm.

In accordance with the first aspect of the invention, the premix gas burner deck plate is made of cast aluminium, e.g. pressure die cast aluminium (including high pressure die cast aluminium) or sand cast aluminium. Cast aluminium has a high thermal conductivity, which makes that it is effective in transferring heat away from the premix gas burner deck plate.

Cast aluminium is an example of a metal having a thermal conductivity coefficient at room temperature of at least 80 W/(mK) and having a Young’s modulus for tension at room temperature of 150GPa or less. Alternatively, instead of aluminium, another metal having a thermal conductivity coefficient at room temperature of at least 80 W/(mK) and having a Young’s modulus for tension at room temperature of 150GPa or less can be used for the premix gas burner deck plate according to the first aspect of the invention. The Young’s modulus for tension at room temperature of 150GPa or less allows that material stresses remain at levels that can be considered acceptable for a viewpoint of thermal fatigue.

Instead of cast aluminium, another metal having the same properties in terms of at least thermal conductivity and Young’s modulus at room temperature with respect to compression and to tension can be used.

Examples of (aluminium) materials that are suitable for use in the premix burner deck plate according to the first aspect of the invention are EN-AC44300 (EN AC-AISi12(Fe), Werkstoff no. 3.2582), EN-AC 42100 (EN AC Si7Mg0.3, Werkstoff no. 3.2371 , LM25), EN- AC43000 (EN AC-AL Si10Mg(a), Werkstoff no. 3.2381).

Tests of the premix gas burner deck plate according to the first aspect of the invention have indicated that the premix gas burner deck plate according to the first aspect of the invention performs well with respect to the risk of the occurrence of flash back.

It is suspected that this may be due to that the relatively small plate thickness near the gas outflow channels prevents significant local cooling by the premix gas flowing through the gas outflow channel. The relatively thin plate near the gas outflow channels is not so effective in terms of heat transfer (that requires a larger plate thickness), so the gas passage area through which the gas outflow channels extend remains rather hot. As a consequence, the premix gas is not heated very much during its passage through the gas outflow channel (the premix gas would usually heat up when it cools the burner deck plate, as the premix gas takes away heat from the burner deck plate when it cools the burner deck plate). So, the premix gas leaves the gas outflow channel and enters the combustion zone at a relatively low temperature.

The flame speed which occurs during combustion is directly linked to the premix gas temperature. A lower temperature of the premix gas results in a lower flame speed, which makes that the actual flames will be relatively far from the premix burner deck plate. This reduces the total heat load on the premix gas burner deck plate. This, together with the larger place thickness in the heat transfer area of the premix burner deck plate, makes that the overall temperature of the premix gas burner deck plate remains relatively low, despite the warmer and thinner gas passage area. This relatively low overall burner deck temperature could be the explanation for the good performance in terms of the risk of the occurrence of flash back.

It is suspected that the use of cast aluminium (or another metal material with similar relevant properties in terms of e.g. thermal conductivity and Young’s modulus for tension) helps to achieve this good performance because of its relatively high thermal conductivity, which is useful for the effectiveness of the heat transfer area or heat transfer areas. In addition, it is suspected that the larger thickness of the heat transfer area or heat transfer areas helps to prevent undesired deformation of the premix gas burner deck plate, in particular undesired bulging of the premix gas burner deck plate.

Tests have also shown that the premix gas burner deck plate according to the first aspect of the invention can be manufactured well and at relatively limited costs from the cast aluminium, in particular pressure die cast aluminium, even when it is desired to limit the number and/or intensity of further manufacturing steps (such as drilling or machining).

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, the gas passage area comprises a plurality of gas outflow channels.

Preferably, the gas outflow channels in the gas passage area are arranged in a predetermined pattern, e.g. in a predetermined pattern that allows for or is even optimized for the combustion of a premix gas in which the fuel gas is or contains hydrogen.

When the premix gas burner deck plate is arranged in a functional heating appliance, thermal stresses will occur in the premix gas burner deck plate due to heating and/or cooling of the premix gas burner deck plate. Expected thermal stresses can be calculated during the design phase of the premix gas burner deck plate using known techniques such as finite element modelling. Expected stresses can for example be derived from measuring local temperatures (e.g. from a prototype) and temperature profiles can be modeled using computation fluid dynamics (CFD) analysis. The expected thermal stresses by definition have principal stress directions. In case of thermal fatigue, fatigue crack propagation can be expected to follow the direction of the largest principal stress associated with the maximum thermal stress.

Optionally, in this embodiment of the premix gas burner deck plate, the pattern in which the gas outflow channels in the gas passage area are arranged is such that any line from the center of one gas outflow channel of the pattern to the center of the closest adjacent gas outflow channel(s) in that same pattern does not coincide with the direction of the largest principal stress associated with the maximum expected thermal stress in the gas passage area in which the gas outflow channel and the respective adjacent gas outflow channel are arranged. Optionally, a line from the center of one gas outflow channel of the pattern to the center of the closest adjacent gas outflow channel(s) in that same pattern extends at an angle of 35°-65°, e.g. an angle of 40°-60°, relative to the direction of the largest principal stress associated with the maximum thermal stress.

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, the premix gas burner deck plate comprises a plurality of gas passage areas, and each gas passage area comprises at least one gas outflow channel. Optionally, at least one gas passage area comprises a plurality of gas outflow channels.

Optionally, multiple gas passage areas comprise a plurality of gas outflow channels Optionally, all gas passage areas comprise a plurality of gas outflow channels. Optionally, multiple gas passage areas are grouped together in a gas discharge zone. Optionally, multiple or all gas passage areas are arranged in a central gas discharge zone, which is for example arranged at a distance from a circumferential edge of the premix gas burner deck plate, for example in the center of the premix gas burner deck plate.

Optionally, the premix gas burner deck plate comprises a plurality of gas discharge zones, wherein multiple gas discharge zones comprise multiple gas passage areas, and wherein optionally all gas discharge zones comprise multiple gas passage areas.

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, the premix gas burner deck plate has a circumferential edge, and the premix gas burner deck plate comprises a plate rim area adjacent to at least a part of the circumferential edge. In this embodiment the premix gas burner deck plate has a third plate thickness in the plate rim area, which third plate thickness is larger than the first plate thickness, optionally equal to or larger than the second plate thickness.

So, in this embodiment, the premix gas burner deck plate has a plate rim area that is thicker than the plate thickness in the gas passage areas. Optionally, in the plate rim area the premix gas burner deck plate is as thick or even thicker than in the heat transfer area or heat transfer areas of the premix gas burner deck plate. This supports the transfer of heat away from the premix gas burner deck plate during use, which in turn helps to keep the premix gas burner deck plate relatively cool and therewith reduces the risk of flashback.

Optionally, the third plate thickness varies over the plate rim area, so different parts of the plate rim area have a different thickness. This allows to tune the temperature distribution over the premix gas burner deck plate that occurs e.g. during use, and/or the distribution of the material stresses (e.g. with respect to the size and/or direction of these stresses) over the premix gas burner deck plate that occurs e.g. during use.

Optionally, in this embodiment, the premix gas burner deck plate further comprises a plurality of gas passage areas, and each gas passage area comprises at least one gas outflow channel. Optionally, at least one gas passage area comprises a plurality of gas outflow channels. Optionally, multiple gas passage areas comprise a plurality of gas outflow channels. Optionally, all gas passage areas comprise a plurality of gas outflow channels. Optionally, multiple gas passage areas are grouped together in a gas discharge zone, which gas discharge zone is arranged closer to a center of the premix gas burner deck plate than the plate rim area. Optionally, multiple or all gas passage areas are arranged in a central gas discharge zone, which central gas discharge zone is arranged closer to a center of the premix gas burner deck plate than the plate rim area.

Optionally, the plate rim area extends along the entire circumference of the premix gas burner deck plate. Optionally, in that case, the gas passage area or multiple gas passage areas or all gas passage areas is/are arranged in a central gas discharge zone are surrounded by the plate rim area.

In an embodiment of the premix gas burner deck plate according to the first aspect of the invention, the premix gas burner deck plate comprises multiple heat transfer areas.

Optionally, multiple heat transfer areas are in thermal contact with each other. Optionally, all heat transfer areas are in thermal contact with each other.

In an embodiment of the premix gas burner deck plate according to the first aspect of the invention, the entire area of the premix gas burner deck plate outside and between the gas passage areas forms the heat transfer area or forms a combination of multiple heat transfer areas.

In an embodiment of the premix gas burner deck plate according to the first aspect of the invention, the premix gas burner deck plate comprises a closed area, which is connected to at least one gas passage area, optionally to multiple gas passage areas, e.g. to all gas passage areas, wherein at least a part of the closed area forms a heat transfer area, the heat transfer area or multiple heat transfer areas. The closed area is closed, i.e. it does not comprise a gas passage area and/or a gas outflow channel. Optionally, the closed area is connected to one or more gas passage areas via a passage rim area.

Optionally, the closed area comprises a first portion and a second portion, which first portion and second portion have a different plate thickness. Optionally, the first portion has a thickness corresponding to the second plate thickness and the second portion has a plate thickness which can be larger or smaller than the second plate thickness.

Optionally, the closed area comprises a first portion and a second portion, which first portion has a thickness corresponding to the second plate thickness and is connected to at least one gas passage area, and which second portion has a plate thickness that is smaller than the second plate thickness. Optionally, the plate thickness of the second portion of the closed area has a plate thickness which is smaller than the second plate thickness and larger than the first plate thickness. The first portion forms a heat transfer area or the heat transfer area or forms part of a heat transfer area or forms part of the heat transfer area. Optionally, the first portion and the second portion both form part of the heat transfer area, or the first portion and the second portion both form part of a heat transfer area. Optionally, the closed area comprises a first portion and a second portion, which first portion has a thickness corresponding to the second plate thickness and is connected to at least one gas passage area, and which second portion has a plate thickness that is larger than the second plate thickness. The first portion and the second portion together form a heat transfer area or the heat transfer area or form part of a heat transfer area or form part of the heat transfer area.

Optionally, the closed area comprises a first portion and a second portion, which first portion has a varying thickness with the second plate thickness as the minimum thickness, and the first portion is connected to at least one gas passage area. The second portion has a plate thickness that is smaller than the second plate thickness, the plate thickness of the second portion being either constant or varying. Optionally, the plate thickness of the second portion of the closed area has a plate thickness which is smaller than the second plate thickness and larger than the first plate thickness. The first portion forms a heat transfer area or the heat transfer area or forms part of a heat transfer area or forms part of the heat transfer area. Optionally, the first portion and the second portion both form part of the heat transfer area, or the first portion and the second portion both form part of a heat transfer area.

Optionally, the closed area comprises a first portion and a second portion, which first portion has a varying thickness with the second plate thickness as the minimum thickness, and the first portion is connected to at least one gas passage area. The second portion has a plate thickness that is larger than the second plate thickness, the plate thickness of the second portion being either constant or varying. The first portion and the second portion together form a heat transfer area or the heat transfer area or form part of a heat transfer area or form part of the heat transfer area.

Optionally, the closed area comprises multiple first portions and at least a second portion, which first portions have a thickness corresponding to the second plate thickness and each first portion being connected to at least one gas passage area. The at least one second portion has a plate thickness that is smaller than the second plate thickness. Optionally, the plate thickness of the at least one second portion of the closed area has a plate thickness which is smaller than the second plate thickness and larger than the first plate thickness. The first portions each form a heat transfer area of form part of a heat transfer area or form part of the heat transfer area. Optionally, the first portions and the at least one second portion all form part of the heat transfer area, or the first portion and the second portion both form part of a heat transfer area.

Optionally, the closed area comprises multiple first portions and at least a second portion, which first portions have a thickness corresponding to the second plate thickness and each first portion being connected to at least one gas passage area. The at least one second portion has a plate thickness that is larger than the second plate thickness, the plate thickness of the second portion being either constant or varying. The first portions and the at least one second portion together form a heat transfer area or the heat transfer area or form part of a heat transfer area or form part of the heat transfer area.

Optionally, the closed area comprises multiple first portions and at least a second portion, and each first portion being connected to at least one gas passage area, and the plate thickness of a first first portion is different from the plate thickness of a second first portion. The plate thickness of the first portion that has the smallest plate thickness is equal to the second plate thickness.

Optionally, the closed area comprises a first portion and a second portion, which first portion has a thickness corresponding to the second plate thickness and the second portion of the closed area has a plate thickness which is smaller than the second plate thickness.

Optionally, the entire area of the premix gas burner deck plate outside and between the gas passage areas forms the closed area.

The variants in which the closed area comprise a first portion and a second portion allow to optimize the heat transfer to outside the premix gas burner deck plate.

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, at least one gas outflow channel is tapered.

So, in this embodiment, the cross-sectional size of the gas outflow channel varies over the length of the gas outflow channel, in such a way that it either increases or decreases from one end of the gas outflow channel to the other end of the gas outflow channel. For example, if the gas outflow channel has a circular cross-section, the diameter of that circular crosssection is larger on one end of the gas outflow channel than on the other end of the gas outflow channel.

For example, the tapered gas outflow channel widens (or, in case of multiple tapered gas outflow channels: the tapered gas outflow channels widen) from the combustion zone side of the premix gas burner deck plate to the distribution chamber side of the premix gas burner deck plate. Good burner deck performance has been observed with this configuration.

Optionally, in this embodiment, the premix gas burner deck plate comprises a plurality of gas outflow channels. Optionally, multiple gas outflow channels of the plurality of gas outflow channels are tapered. Optionally, all gas outflow channels of the plurality of gas outflow channels are tapered.

The taper angle of the gas outflow channel is optionally at least 6°, for example at least 9°, optionally at least 12°. The diameter at an end of the gas outflow channel, e.g. at the end with the smallest diameter, is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm. In case the diameter is constant over the length of the gas outflow channel, the diameter at an end of the gas outflow channel is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm. An advantage of this embodiment is that a premix gas burner deck plate in accordance with this aspect of the first aspect of the invention contributes to easy removal of the premix gas burner deck plate from a die when the premix gas burner deck plate is made by pressure die casting and the gas outflow channels are formed in the pressure die casting process.

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, at least one gas outflow channel comprises a first channel portion which extends over a part of the length of said gas outflow channel, and this first channel portion is tapered.

So, in this embodiment, the cross-sectional size of the first channel portion of the gas outflow channel varies over the length of said first channel portion, in such a way that it either increases or decreases from one end of the first channel portion to the other end of the second channel portion. For example, if the first channel portion has a circular cross-section, the diameter of that circular cross-section is larger on one end of the first channel portion than on the other end of the first channel portion.

Optionally, the gas outflow channel further comprises a second channel portion which extends over a part of the length of said gas outflow channel, which second channel portion of said gas outflow channel has a constant diameter. Optionally the first channel portion and the second channel portion together form the gas outflow channel.

An advantage of this embodiment is that is appears to provide a stable gas flow through the gas outflow channel.

For example, the first channel portion of the gas outflow channel widens (or, in case of multiple tapered gas outflow channels: the tapered part of the gas outflow channels widen) from the combustion zone side of the premix gas burner deck plate towards the distribution chamber side of the premix gas burner deck plate, and the second channel portion of the same gas outflow channel, which second channel portion has a constant diameter, is located closer to the combustion zone side of the premix gas burner deck than to the distribution chamber side of the premix gas burner deck plate. Good burner deck performance has been observed with this configuration.

Optionally, the first channel portion has a circular cross section and the second channel portion also has a circular cross section.

Optionally, the diameter of the second channel portion is the same as the smallest diameter of the first channel portion. Alternatively, the diameter of the second channel portion is the same as the largest diameter of the first channel portion.

Optionally, in this embodiment, the premix gas burner deck plate comprises a plurality of gas outflow channels. Optionally, multiple gas outflow channels of the plurality of gas outflow channels are tapered over a part of their length. Optionally, all gas outflow channels of the plurality of gas outflow channels are tapered over a part of their length.

The taper angle of the first channel portion is optionally at least 6°, for example at least 9°, optionally at least 12°. The diameter at an end of the first channel portion, e.g. at the end with the smallest diameter, is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm. The diameter of the second channel portion is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm.

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, a passage rim area is provided around at least one gas passage area, and the premix gas burner deck plate has a fourth plate thickness in the passage rim area. The fourth plate thickness is larger than the first plate thickness, optionally equal to or larger than the second plate thickness. Optionally, in case a plate rim area is present, the fourth plate thickness is equal to the third plate thickness.

It is suspected that this contributes to obtaining the desired temperature distribution over the premix gas burner deck plate during use.

Optionally, the fourth plate thickness varies over the passage rim area, so different parts of the passage rim area have a different thickness. This allows to tune the temperature distribution over the premix gas burner deck plate that occurs e.g. during use, and/or the distribution of the material stresses (e.g. with respect to the size and/or direction of these stresses) over the premix gas burner deck plate that occurs e.g. during use.

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, the combustion zone side of the premix gas burner deck plate is planar. So, in this embodiment, the combustion zone side of the premix gas burner deck plate is devoid of protrusions and indents.

It is suspected that this contributes to obtaining a relatively low burner deck temperature of the premix gas burner deck plate during use.

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, the premix gas burner deck plate is manufactured by machining a cast aluminium plate.

For example, the final thickness of the gas passage area or gas passage areas is obtained by machining and the gas outflow channel or gas outflow channels is/are formed by drilling, punching or laser cutting. Optionally, the final thickness of the heat transfer area(s) is obtained by machining as well.

In this embodiment, the material of the premix gas burner deck plate has a structure which is typical for cast parts which are later machined to the desired shape. In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, the premix gas burner deck plate is manufactured by forging and/or pressing a cast aluminum plate.

Optionally, the rough shape of the premix gas burner deck plate is obtained by forging and/or pressing, and the final thickness of the gas passage area or gas passage areas is obtained by machining and the gas outflow channel or gas outflow channels is/are formed by drilling, punching or laser cutting. Optionally, the final thickness of the heat transfer area(s) is obtained by machining as well.

In this embodiment, the material of the premix gas burner deck plate has a structure which is typical for cast parts which are later forged/pressed and then machined to the desired shape.

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, at least the heat transfer area(s) and/or the gas passage area(s) of the premix gas burner deck plate are manufactured by a pressure die casting process, for example a high pressure die casting process.

In this embodiment, the premix gas burner deck plate is generally formed in a pressure die casting process. For example, different material thicknesses are provided for the gas passage area(s) and the heat transfer area(s). Optionally, the pressure die cast premix gas burner deck plate is machined after pressure die casting in order to make sure the required manufacturing tolerances are met, but in this embodiment the general shape of the premix gas burner deck plate is obtained by pressure die casting.

In this embodiment, the material of the premix gas burner deck plate has a structure which is typical for pressure die cast parts.

Optionally, in this embodiment, also the gas outflow channel(s) of the premix gas burner deck plate is/are formed in the pressure die casting process. Optionally, a plurality of the gas outflow channels of the premix gas burner deck plate is formed in the pressure die casting process. Optionally, all gas outflow channels of the premix gas burner deck plate are formed in the pressure die casting process.

The design of the premix gas burner deck plate is suitable for manufacturing by a pressure die cast process, e.g. a high pressure die cast process. This allows the premix gas burner deck plate according to the first aspect of the invention to be manufactured at relatively low costs and relatively high speeds, in particular when single shot (high) pressure die casting is used. The premix gas burner deck plate according to the first aspect of the invention allows manufacturing using single shot pressure die casting, e.g. single shot high pressure die casting. Optionally, the die comprises multiple mould cavities so that multiple premix gas burner deck plates can be cast in one single shot. In this embodiment, the material of the premix gas burner deck plate has a structure which is typical for pressure die cast parts.

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, the premix gas burner deck plate comprises a plurality of gas passage areas, and each gas passage area comprises at least one gas outflow channel, and multiple gas passage areas are arranged in a gas discharge zone. In this embodiment, the premix gas burner deck plate further has a circumferential edge. The premix gas burner deck plate further comprises a plate rim area adjacent to at least a part of the circumferential edge and at least partly surrounding the gas discharge zone. The premix gas burner deck plate has a third plate thickness in the plate rim area, the third plate thickness being larger than the first plate thickness, optionally equal to or larger than the second plate thickness.

This embodiment is particularly suitable for use in a premix gas burner which is designed in such a way that during use the gas discharge zone is subjected to compression stress. The arrangement of the gas discharge zone with the gas passage areas with relatively small local plate thickness in combination with the plate rim area with larger plate thickness allows to design the premix gas burner such that the plate rim area stays relatively cool and the gas discharge zone is relatively warm. In addition, the thicker plate rim area provides additional strength and additional stiffness, e.g. a higher resistance against bulging.

Thermal expansion of the gas discharge zone is this way limited, which results in compression stresses in the gas discharge zone of the premix gas burner deck plate. Compression stresses are far less likely to induce thermal fatigue cracking than tensile stresses, so having compression stresses in the area where the gas outflow channels (and therefore the stress concentrations due to holes in the premix gas burner deck plate) is likely to contribute to a longer life span of the premix gas burner deck plate from a fatigue point of view. In addition, tests carried out by the applicant seem to suggest that the Young’s modulus for compression (sometimes also referred to in the art as compression modulus or elasticity modulus for compression) of cast aluminium (e.g. pressure die cast aluminium or sand cast aluminium) is significantly lower than the Young’s modulus for tension, even as much as 1.5 - 2 times lower, up to 3 or even 3.5 times lower. As a result of this, the compression stresses in the gas discharge zone can be expected to be relatively low. This also contributes to a longer life span of the premix gas burner deck plate from a fatigue point of view. In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, the premix gas burner deck plate is at least partly provided with a coating, e.g. an anti-corrosion coating. For example, a coating is used which provides protection against sulphur induced and/or corrosion due to the presence of nitric acid. Sulphur containing substances are sometimes added to fuel gas as odorants, but they may cause corrosion of metals, in particular when they are combusted with oxygen, and react with water H2SO4 is formed, which can be highly corrosive. Nitric acid may be formed out of NOx (e.g. NO, NO2 or N2O) which results from the combustion of the premix gas, in combination with any water that may be present.

Optionally, the coating is present at least on a part of the combustion zone side of the premix gas burner deck plate and/or on an inner wall of the gas outflow channel.

Optionally, a surface roughness is provided on the premix gas burner deck plate prior to applying the coating, e.g. during a pressure die casting process or sand casting process in which the premix gas burner deck plate is formed.

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, the premix gas burner deck plate comprises a curved portion having a radius of curvature, and multiple gas outflow channels are provided in the curved portion, each of the gas outflow channels in the curved portion having a longitudinal axis. In this embodiment, the longitudinal axes of all gas outflow channels in the curved portion are parallel to each other.

An advantage of this embodiment is that a premix gas burner deck plate in accordance with this aspect of the first aspect of the invention contributes to easy removal of the premix gas burner deck plate from a die when the premix gas burner deck plate is made by pressure die casting and the gas outflow channels are formed in the pressure die casting process.

Optionally, the longitudinal axis of at least one of the multiple gas outflow channels in the curved portion extends in the radial direction of the radius of curvature.

In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, multiple gas outflow channels are provided in the premix gas burner deck plate, each of the gas outflow channels having a longitudinal axis. In this embodiment, the longitudinal axes of all gas outflow channels are parallel to each other.

An advantage of this embodiment is that a premix gas burner deck plate in accordance with this aspect of the first aspect of the invention contributes to easy removal of the premix gas burner deck plate from a die when the premix gas burner deck plate is made by pressure die casting and the gas outflow channels are formed in the pressure die casting process. In an embodiment of the premix gas burner deck plate in accordance with the first aspect of the invention, the gas outflow channel has an inner wall and the gas passage area has an outer surface at the distribution chamber side of the premix gas burner deck plate, and the inner wall of the gas outflow channel meets the outer surface of the gas passage area at the distribution chamber side of the premix gas burner deck plate via a rounded edge.

Optionally, multiple gas outflow channels each have an inner wall and the gas passage area has an outer surface at the distribution chamber side of the premix gas burner deck plate, and the inner wall of each gas outflow channel meets the outer surface of the gas passage area at the distribution chamber side of the premix gas burner deck plate via a rounded edge.

Optionally, all gas outflow channels each have an inner wall and the gas passage area has an outer surface at the distribution chamber side of the premix gas burner deck plate, and the inner wall of each gas outflow channel meets the outer surface of the gas passage area at the distribution chamber side of the premix gas burner deck plate via a rounded edge.

It is suspected that this embodiment contributes to further reducing the risk of flashback, possibly because a smooth flow of premix gas into the gas outflow channel(s) is obtained and negative local pressure at the entrance into the gas outflow channel(s) is reduced or avoided.

In a second aspect, the invention pertains to a premix gas burner deck plate, which premix gas burner deck plate has a distribution chamber side and a combustion zone side, which distribution chamber side and combustion zone side are located on opposite sides of the premix gas burner deck plate, which premix gas burner deck plate further comprises a gas discharge zone, which gas discharge zone has a center and an edge, and a cross-sectional shape having a thickness that is smaller at the center than at the edge, wherein the gas discharge zone comprises:

- a gas passage area, which comprises at least one gas outflow channel which is adapted to during use supply premix gas to a combustion zone, and

- a heat transfer area, wherein at least a part of the heat transfer area is arranged adjacent to and at least partly extends around the gas passage area, wherein the gas outflow channel extends from the distribution chamber side of the premix gas burner deck plate to the combustion zone side of the premix gas burner deck plate, and wherein the premix gas burner deck plate is made of cast aluminium.

Optionally, multiple gas passage areas are provided. Optionally, a plurality of gas passage areas is embedded in the heat transfer area. Optionally, all gas passage areas are embedded in the heat transfer area. Like in the premix gas burner deck plate according to the first aspect of the invention, the premix gas burner deck plate according to the second aspect of the invention has relatively short gas outflow channels as compared to the thickness of the part of the heat transfer area adjacent to the gas outflow area. This makes that the premix gas flowing through the gas outflow channels does not heat up so much and leaves the burner deck at a relatively low temperature. This results in a relatively low flame speed, which makes that during use the flames will be relatively far away from the premix gas burner deck plate.

It is suspected that this makes that the premix gas burner deck plate according to the second aspect of the invention performs well with respect to the risk of the occurrence of flash back.

The flame speed which occurs during combustion is directly linked to the premix gas temperature. A lower temperature of the premix gas results in a lower flame speed, which makes that the actual flames will be relatively far from the premix burner deck plate. This reduces the total heat load on the premix gas burner deck plate. This, together with the larger plate thickness in the heat transfer area of the premix burner deck plate, makes that the overall temperature of the premix gas burner deck plate remains relatively low, despite the warmer and thinner gas passage area. This relatively low overall burner deck temperature could be the explanation for the good performance in terms of the risk of the occurrence of flash back.

It is suspected that the use of cast aluminium (or another metal material with similar relevant properties in terms of e.g. thermal conductivity and Young’s modulus for tension) helps to achieve this good performance because of its relatively high thermal conductivity, which is useful for the effectiveness of the heat transfer area or heat transfer areas.

In addition, it is suspected that the thickness of the heat transfer area or heat transfer areas helps to prevent undesired deformation of the premix gas burner deck plate, in particular undesired bulging of the premix gas burner deck plate.

The premix gas burner deck plate according to the second aspect of the invention can be manufactured well and at relatively limited costs from the cast aluminium, in particular pressure die cast aluminium, even when it is desired to limit the number and/or intensity of further manufacturing steps (such as drilling or machining).

In an embodiment, the gas discharge zone of the premix burner deck plate according to the second aspect of the invention has a first plate thickness in the gas passage area, which first plate thickness is smaller than the thickness of the gas discharge zone in the at least part of the heat transfer area that is arranged adjacent to and extends at least partly around the gas passage area. This embodiment results in a combination of the first aspect of the invention and the second aspect of the invention.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, the thickness of the gas discharge zone changes continuously from the center of the gas discharge zone to the edge of the gas discharge zone.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, the thickness of the gas discharge zone changes in a stepwise manner from the center of the gas discharge zone to the edge of the gas discharge zone.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, the gas discharge zone has a concave shape on the distribution chamber side and/or on the combustion zone side.

Optionally, in this embodiment an indentation is provided in the cross-sectional shape of the gas discharge zone at the location of the gas passage area, which indentation is preferably located on the distribution chamber side.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, the gas passage area comprises a plurality of gas outflow channels.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, the gas discharge zone comprises a plurality of gas passage areas, and each gas passage area is arranged adjacent to and surrounded by at least a part of the heat transfer area.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, the premix gas burner deck plate has a circumferential edge, and the premix gas burner deck plate comprises a plate rim area adjacent to at least a part of the circumferential edge, and the premix gas burner deck plate has a third plate thickness in the plate rim area. In this embodiment, the third plate thickness is larger than the first plate thickness, optionally equal to or larger than a maximum thickness of the gas discharge zone.

This supports the transfer of heat away from the premix gas burner deck plate during use, which in turn helps to keep the premix gas burner deck plate relatively cool and therewith reduces the risk of flashback.

Optionally, in this embodiment, the premix gas burner deck plate further comprises a plurality of gas passage areas, and each gas passage area comprises at least one gas outflow channel. Optionally, at least one gas passage area comprises a plurality of gas outflow channels. Optionally, multiple gas passage areas comprise a plurality of gas outflow channels. Optionally, all gas passage areas comprise a plurality of gas outflow channels.

Optionally, the plate rim area extends along the entire circumference of the premix gas burner deck plate.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, at least one gas outflow channel is tapered. So, in this embodiment, the cross-sectional size of the gas outflow channel varies over the length of the gas outflow channel, in such a way that it either increases or decreases from one end of the gas outflow channel to the other end of the gas outflow channel. For example, if the gas outflow channel has a circular cross-section, the diameter of that circular crosssection is larger on one end of the gas outflow channel than on the other end of the gas outflow channel.

The taper angle of the gas outflow channel is optionally at least 6°, for example at least 9°, optionally at least 12°. The diameter at an end of the gas outflow channel, e.g. at the end with the smallest diameter, is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm. In case the diameter is constant over the length of the gas outflow channel, the diameter at an end of the gas outflow channel is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm.

An advantage of this embodiment is that a premix gas burner deck plate in accordance with this aspect of the second aspect of the invention contributes to easy removal of the premix gas burner deck plate from a die when the premix gas burner deck plate is made by pressure die casting and the gas outflow channels are formed in the pressure die casting process.

In an embodiment of the premix gas burner deck plate in accordance with the second aspect of the invention, at least one gas outflow channel comprises a first channel portion which extends over a part of the length of said gas outflow channel, and this first channel portion is tapered.

For example, the first channel portion of the gas outflow channel widens (or, in case of multiple tapered gas outflow channels: the tapered part of the gas outflow channels widens) from the combustion zone side of the premix gas burner deck plate towards the distribution chamber side of the premix gas burner deck plate, and the second channel portion of the same gas outflow channel, which second channel portion has a constant diameter, is located closer to the combustion zone side of the premix gas burner deck than to the distribution chamber side of the premix gas burner deck plate. Good burner deck performance has been observed with this configuration.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, a passage rim area is provided around at least one gas passage area, and the premix gas burner deck plate has a fourth plate thickness in the passage rim area,

In this embodiment, the fourth plate thickness is larger than the first plate thickness, optionally equal to or larger than a maximum thickness of the gas discharge zone in the at least part of the heat transfer area that is arranged adjacent to and extends at least partly around the gas passage area.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, the combustion zone side of the premix gas burner deck plate is planar.

So, in this embodiment, the combustion zone side of the premix gas burner deck plate is devoid of protrusions and indents.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, at least the heat transfer area and/or the gas passage area of the premix gas burner deck plate are manufactured by a pressure die casting process, e.g. a high pressure die casting process.

Optionally, further the gas outflow channel of the premix gas burner deck plate is formed in the pressure die casting process, e.g. the high pressure die casting process.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, the premix gas burner deck plate is at least partly provided with a coating, e.g. an anti-corrosion coating.

Optionally the coating is present at least on a part of the combustion zone side of the premix gas burner deck plate and/or on an inner wall of the gas outflow channel.

For example, a coating is used which provides protection against sulphur induced corrosion and/or corrosion due to the presence of nitric acid. Sulphur containing substances are sometimes added to fuel gas as odorants, but they may cause corrosion of metals, in particular when they are combusted with oxygen, and react with water H2SO4 is formed, which can be highly corrosive. Nitric acid may be formed out of NOx (e.g. NO, NO2 or N2O) which results from the combustion of the premix gas, in combination with any water that may be present.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, the premix gas burner deck plate comprises a curved portion having a radius of curvature, and wherein multiple gas outflow channels are provided in the curved portion, each of the gas outflow channels in the curved portion having a longitudinal axis. In this embodiment, the longitudinal axes of all gas outflow channels in the curved portion are parallel to each other.

In an embodiment of the premix gas burner deck plate in accordance with the second aspect of the invention, multiple gas outflow channels are provided in the premix gas burner deck plate, each of the gas outflow channels having a longitudinal axis. In this embodiment, the longitudinal axes of all gas outflow channels are parallel to each other.

In an embodiment of the premix burner deck plate according to the second aspect of the invention, the gas outflow channel has an inner wall and the gas passage area has an outer surface at the distribution chamber side of the premix gas burner deck plate. In this embodiment, the inner wall of the gas outflow channel meets the outer surface of the gas passage area at the distribution chamber side of the premix gas burner deck plate via a rounded edge.

Optionally, all gas outflow channels each have an inner wall and the gas passage area has an outer surface at the distribution chamber side of the premix gas burner deck plate, and the inner wall of each gas outflow channel meets the outer surface of the gas passage area at the distribution chamber side of the premix gas burner deck plate via a rounded edge. It is suspected that this embodiment contributes to further reducing the risk of flashback, possibly because a smooth flow of premix gas into the gas outflow channel(s) is obtained and negative local pressure at the entrance into the gas outflow channel(s) is reduced or avoided.

The invention further pertains to a premix gas burner comprising a premix gas burner deck plate according to the first aspect or second aspect of the invention.

In an embodiment of the premix gas burner in accordance with the invention, the premix gas burner comprises a gas distribution chamber, which gas distribution chamber is at least partly delimited by the premix gas burner deck plate.

For example, the premix gas burner in this embodiment further comprises a premix gas supply which is adapted to supply premix gas to the gas distribution chamber.

From the gas distribution chamber, the premix gas flows through the gas outflow channel(s) of the premix gas burner deck plate to the combustion zone, where the combustion of the premix gas takes place.

Optionally, a gas distributor is arranged in the gas distribution chamber, in order to equally distribute the premix gas over multiple gas outflow channels of the premix gas burner deck plate. In addition, the gas distributor could be useful in reducing thermo-acoustic sound generation.

In an embodiment of the premix gas burner in accordance with the invention, a premix gas burner deck plate is used which comprises a plurality of gas passage areas, and each gas passage area comprises at least one gas outflow channel, and multiple gas passage areas are arranged in a gas discharge zone. In this embodiment, the premix gas burner deck plate further has a circumferential edge. The premix gas burner deck plate further comprises a plate rim area adjacent to at least a part of the circumferential edge and at least partly surrounding the gas discharge zone. The premix gas burner deck plate has a third plate thickness in the plate rim area, the third plate thickness being larger than the first plate thickness, optionally equal to or larger than the second plate thickness.

In this embodiment, the premix gas burner deck plate is mounted into the premix gas burner in such a way that during use, i.e. when premix gas is combusted, the gas discharge zone is subjected to compression stress. Optionally, the gas discharge zone of the premix gas burner deck plate is subjected to compression stress when the combustion of the premix gas has reached a steady state and/or when the temperature distribution in the premix gas burner deck plate has reached a steady state. Optionally, the gas discharge zone of the premix gas burner deck plate is subjected to compression stress at some locations and to tensile stress at other locations, and the maximum compression stress is higher than the maximum tensile stress and/or the total areas of the gas discharge zone of the premix gas burner deck plate that is subjected to compression stress is larger than the total area of the gas discharge zone of the premix burner deck plate that is subjected to tensile stress. Optionally, when the combustion of the premix gas has reached a steady state and/or when the temperature distribution in the premix gas burner deck plate has reached a steady state, the gas discharge zone of the premix gas burner deck plate is subjected to compression stress at some locations and to tensile stress at other locations, and the maximum compression stress is higher than the maximum tensile stress and/or the total area of the gas discharge zone of the premix gas burner deck plate that is subjected to compression stress is larger than the total area of the gas discharge zone of the premix burner deck plate that is subjected to tensile stress.

The arrangement of the gas discharge zone with the gas passage areas with relatively small local plate thickness in combination with the plate rim area with larger plate thickness allows to design the premix gas burner such that the plate rim area stays relatively cool and the gas discharge zone is relatively warm. In addition, the thicker plate rim area provides additional strength and additional stiffness, e.g. a higher resistance against bulging.

Thermal expansion of the gas discharge zone is this way limited or even prevented, which results in compression stresses in the gas discharge zone of the premix gas burner deck plate.

In addition, in this embodiment, optionally the mounting of the premix gas burner deck plate in the premix gas burner is adapted to (of even optimized to) ensure that indeed compression stress is obtained in the gas discharge zone.

Compression stresses are far less likely to induce thermal fatigue cracking than tensile stresses, so having compression stresses in the area where the gas outflow channels (and therefore the stress concentrations due to holes in the premix gas burner deck plate) is likely to contribute to a longer life span of the premix gas burner deck plate from a fatigue point of view. In addition, tests carried out by the applicant seem to suggest that the Young’s modulus for compression (sometimes also referred to in the art as compression modulus or elasticity modulus for compression) of cast aluminium (e.g. pressure die cast aluminium or sand cast aluminium) is significantly lower than the Young’s modulus for tension, even as much as 1.5 - 2 times lower, up to 3 or even 3.5 times lower. As a result of this, the compression stresses in the gas discharge zone can be expected to be relatively low. This also contributes to a longer life span of the premix gas burner deck plate from a fatigue point of view.

Optionally, in this embodiment, the plate rim area of the premix gas burner deck plate is in thermal contact with a heat sink. The heat sink can be a dedicated heat sink element, or a part of e.g. a body of the premix gas burner, a gas distribution chamber of the premix gas burner or the like may function as a heat sink for the plate rim area. The thermal contact between the plate rim area and the heat sink may be either direct or indirect.

In an embodiment of the premix gas burner in accordance with the invention, the heat transfer area or heat transfer areas of the premix gas burner deck plate is in thermal contact with a heat sink. The heat sink can be a dedicated heat sink element, or a part of e.g. a body of the premix gas burner, a gas distribution chamber of the premix gas burner or the like may function as a heat sink for the heat transfer area or heat transfer areas. The thermal contact between the heat transfer area or heat transfer areas and the heat sink may be either direct or indirect.

In an embodiment of the premix gas burner in accordance with the invention, the premix gas burner comprises a mounting flange which allows to mount the premix gas burner to a heat exchanger, which mounting flange is designed to allow heat transfer from the premix gas burner to the heat exchanger.

Preferably, the premix gas burner is mountable to the heat exchanger in a floating manner.

The invention further pertains to a heating appliance, which is for example a heater system for a building or a domestic hot water system.

The heating appliance according to the invention comprises a premix gas burner according to invention and a heat exchanger.

Optionally, the premix gas burner deck plate of the premix gas burner is in thermal contact with the heat exchanger.

Optionally, the premix gas burner and the heat exchanger are made of the same material.

Optionally, the premix gas burner and the heat exchanger are integral with each other, e.g. in the form of an integrally cast aluminium element.

The invention further pertains to a method for manufacturing a premix gas burner deck plate according to the first aspect or to the second aspect of the invention, which method comprises: - pressure die casting the premix gas burner deck plate in a die, wherein the gas passage area and/or the gas outflow channel are formed in the die.

In case the premix gas burner deck plate comprises a plurality of gas passage areas, optionally multiple gas passage areas are formed in the die. Optionally, in that case, all gas passage areas are formed in the die.

In case the premix gas burner deck plate comprises a plurality of gas outflow channels, optionally multiple gas outflow channels are formed in the die. Optionally, in that case, all gas outflow channels are formed in the die.

The premix gas burner deck plate according to the invention is suitable for pressure die casting, e.g. for high pressure die casting. This allows high production speeds and low manufacturing costs.

Optionally, the method further comprises the step of machining the premix gas burner deck plate to the desired shape and/or required manufacturing tolerances and/or required surface roughness.

As an alternative for pressure die casting, sand casting can be used.

Advantageously, the gas passage area(s) and the gas outflow channel(s) are both formed in the die, as this reduces the number of post-casting machining actions.

In an embodiment of the method for manufacturing a premix gas burner deck plate in accordance with the first aspect or the second aspect of the invention, a tapered gas outflow channel is formed in the die during the pressure die casting.

In case the premix gas burner deck plate comprises a plurality of gas outflow channels, optionally multiple gas flow channels are tapered gas outflow channels and are formed in the die during the pressure die casting. Optionally, in that case, all gas outflow channels are tapered and are formed in the die.

Optionally, the taper angle of a tapered gas outflow channel is optionally at least 6°, for example at least 9°, optionally at least 12°.

An advantage of this embodiment is that it contributes to easy removal of the premix gas burner deck plate from a die when the premix gas burner deck plate is made by pressure die casting and the tapered gas outflow channels are formed in the pressure die casting process.

Optionally, in a variant of this embodiment, the method further comprises the step of:

- after the pressure die casting, tuning a local diameter of a gas outflow channel by removing material from the premix gas burner deck plate adjacent to the tapered gas outflow channel.

The material can for example be removed by machining. Due to the tapered shape of the gas outflow channel(s), by removing a small amount of material adjacent to the tapered gas outflow channel, the diameter of the opening of the gas outflow channel in the outer surface of the gas passage are increases somewhat. In particular the smallest opening of the tapered gas outflow channel determines the pressure drop over the gas outflow channel, which is an important parameter in the design of the premix gas burner deck plate. So, by removing more or less material adjacent to the tapered gas outflow channel, in particular on the side of the opening with the smallest diameter, the pressure drop over the tapered gas outflow channel can be finetuned.

In an embodiment of the method for manufacturing a premix gas burner deck plate in accordance with the first aspect or the second aspect of the invention, a gas outflow channel is formed in the die during the pressure die casting which gas outflow channel comprises a first channel portion, which first channel portion is tapered.

Optionally, the gas outflow channel which is formed in the die during the pressure die casting further comprises a second channel portion which extends over a part of the length of said gas outflow channel, which second channel portion of said gas outflow channel has a constant diameter. Optionally the first channel portion and the second channel portion together form the gas outflow channel.

Pressure die casting is a suitable process to form such a relatively complex geometry.

In an embodiment of the method for manufacturing a premix gas burner deck plate in accordance with the first aspect or the second aspect of the invention, the method further comprises the step of:

- after the pressure die casting, applying a coating to at least a part of the premix gas burner deck plate, wherein optionally the coating is applied at least on a part of the combustion zone side of the premix gas burner deck plate and/or on an inner wall of the gas outflow channel.

Optionally, a surface roughness is provided on the premix gas burner deck plate prior to applying the coating, e.g. during the pressure die casting process or sand casting process in which the premix gas burner deck plate is formed. 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 shows in:

Fig. 1 : schematically, a first embodiment of a premix gas burner deck plate according to the first aspect of the invention,

Fig. 2: schematically, a cross section of the premix gas burner deck plate according to fig. 1 , along line A-A of fig. 1 ,

Fig. 3: schematically, a second embodiment of a premix gas burner deck plate according to the first aspect of the invention,

Fig. 4: schematically, a cross section of the premix gas burner deck plate according to fig. 3, along line A-A of fig. 3,

Fig. 5: schematically, an example of a design of a gas passage area as can be used in a premix gas burner deck plate according to the first and/or second aspect of the invention,

Fig. 6: schematically, a first embodiment of a premix gas burner according to the invention,

Fig. 7: schematically, a further embodiment of a premix gas burner deck plate according to the invention, in which the first aspect of the invention and second aspect of the invention are combined,

Fig. 8: schematically, a cross section of the premix gas burner deck plate according to fig. 7, along line A-A of fig. 7,

Fig. 9: schematically, an embodiment of a premix gas burner deck plate according to the second aspect of the invention,

Fig. 10: schematically, a cross section of the premix gas burner deck plate according to fig. 9, along line A-A of fig. 9,

Fig. 11 : schematically, a further example of a design of a gas passage area as can be used in a premix gas burner deck plate according to the first aspect and/or second aspect of the invention,

Fig. 12: schematically, a portion of a further embodiment of a premix gas burner deck plate according to the first aspect of the invention,

Fig. 13: schematically, a cross-section along line B-B of the embodiment of fig. 12.

Fig. 1 shows, schematically, a first embodiment of a premix gas burner deck plate 1 according to the first aspect of the invention. Fig. 2 shows, schematically, a cross section of the premix gas burner deck plate 1 according to fig. 1, along line A-A of fig. 1.

The premix gas burner deck plate of fig. 1 and fig. 2 has a distribution chamber side 2 and a combustion zone side 3. The distribution chamber side 2 and combustion zone side 3 are located on opposite sides of the premix gas burner deck plate 1. When the premix gas burner deck plate 1 is arranged in a premix gas burner, the distribution chamber side 2 of the premix gas burner deck plate 1 faces towards a gas distribution chamber of the premix gas burner, so, in upstream direction of the flow of the premix gas. When the premix gas burner deck plate 1 is arranged in a premix gas burner, the combustion zone side 3 of the premix gas burner deck plate faces towards a combustion zone in which the actual combustion of the premix gas takes place, so, in downstream direction of the flow of the premix gas.

The premix gas burner deck plate according to fig. 1 and fig. 2 comprises a plurality of gas passage areas 10 and a heat transfer area 5. All the recesses shown in fig. 1 are gas passage areas 10. Premix gas passes from the distribution chamber side 2 of the premix gas burner deck plate 1 to the combustion zone side 3 of the premix gas burner deck plate 1 via the gas passage areas 10. The heat transfer area 5 is designed for effective heat transfer, with the aim of avoiding high burner deck temperatures in the premix gas burner deck plate Iduring use.

The premix gas burner deck plate 1 has a first plate thickness 11 in the gas passage area and a second plate thickness 6 in the heat transfer area 5. The second plate thickness 6 is larger than the first plate thickness 11. For example, the first plate thickness is 0.5 millimeters (mm) up to and including 1 .5 millimeters (mm), for example 1 millimeter (mm). For example, the second plate thickness is 1.5 millimeters (mm) to 10 millimeters (mm), e.g. 2 milimeters (mm) up to and including 7 millimeters (mm), for example 2.5 millimeters (mm) to 6 millimeters (mm), e.g. 5 millimeters (mm) or 3 millimeters (mm). For example, the first thickness is 1 mm and the second plate thickness is 3 mm. Of course, in case the first thickness is 1.5 mm, the second plate thickness is more than 1.5 mm.

In the embodiment of fig.1 and fig. 2, the premix gas burner deck plate 1 comprises a plurality of gas outflow channels 12, each of which is adapted to during use supply premix gas to the combustion zone, in which combustion zone the combustion of the premix gas takes place during use of the premix gas burner deck plate 1 in a premix gas burner. The combustion zone is usually present adjacent to but just outside of the premix gas burner in which the premix gas burner deck plate is arranged. The gas outflow channels 12 are arranged in the gas passage area 10 and extend through the first plate thickness 11 from the distribution chamber side 2 of the premix gas burner deck plate 1 to the combustion zone side 3 of the premix gas burner deck plate 1 .

In the embodiment of fig.1 and fig. 2, each gas passage area 10 comprises a plurality of gas outflow channels 12. The gas outflow channels 12 in each gas passage area 10 are arranged in a predetermined pattern that allows for or is even optimized for the combustion of a premix gas in which the fuel gas is or contains hydrogen

For example, the gas outflow channels 12 all have a circular cross-sectional shape, with a diameter that is either constant or varies over the length of the gas outflow channel 12. In case the diameter varies over the length of the gas outflow channel 12, the gas outflow channel 12 is for example tapered. The taper angle of the gas outflow channel is optionally at least 6°, for example at least 9°, optionally at least 12°. The diameter at an end of the gas outflow channel 12, e.g. at the end with the smallest diameter, is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm. In case the diameter is constant over the length of the gas outflow channel 12, the diameter at an end of the gas outflow channel 12 is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm.

In the embodiment of fig.1 and fig. 2, the premix gas burner deck plate 1 is made of cast aluminium, e.g. pressure die cast aluminium (including high pressure die cast aluminium) or sand cast aluminium. Cast aluminium has a high thermal conductivity, which makes that it is effective in transferring heat away from the premix gas burner deck plate.

Examples of (aluminium) materials that are suitable for use in the premix burner deck plate 1 according to the embodiment of fig.1 and fig. 2, are EN-AC44300 (EN AC-AISi12(Fe), Werkstoff no. 3.2582), EN-AC 42100 (EN AC Si7Mg0.3, Werkstoff no. 3.2371 , LM25), EN- AC43000 (EN AC-AL Si10Mg(a), Werkstoff no. 3.2381).

In the embodiment of fig. 1 and fig. 2, the combustion zone side of the premix gas burner deck plate 1 is planar. So, in this embodiment, the combustion zone side 3 of the premix gas burner deck plate 1 is devoid of protrusions and indents.

In the embodiment of fig. 1 and fig. 2, optionally at least the heat transfer area 5 and the gas passage areas 10 of the premix gas burner deck plate 1 are manufactured by a pressure die casting process, for example a high pressure die casting process.

The premix gas burner deck plate 1 is then generally formed in a pressure die casting process. For example, different material thicknesses are provided for the gas passage areas 10 and the heat transfer area 5. Optionally, the pressure die cast premix gas burner deck plate 1 is machined after pressure die casting in order to make sure the required manufacturing tolerances are met, but in this embodiment the general shape of the premix gas burner deck plate is obtained by pressure die casting.

Optionally, also the gas outflow channels 12 of the premix gas burner deck plate 1 are formed in the pressure die casting process.

Optionally, in the embodiment of fig.1 and fig. 2, the premix gas burner deck plate 1 is at least partly provided with a coating, e.g. an anti-corrosion coating. For example, a coating is used which provides protection against sulphur induced corrosion and/or corrosion due to the presence of nitric acid. Optionally, a surface roughness is provided on the premix gas burner deck plate prior to applying the coating, e.g. during the pressure die casting process. As can be seen in fig. 2, in this embodiment, each of the gas outflow channels has a longitudinal axis and the longitudinal axes of all gas outflow channels 12 are parallel to each other.

In the embodiment of fig. 1 and fig. 2, optionally all gas outflow channels 12 each have an inner wall and the gas passage area 10 has an outer surface at the distribution chamber side of the premix gas burner deck plate, and the inner wall of each gas outflow channel 12 meets the outer surface of the gas passage area 10 at the distribution chamber side of the premix gas burner deck plate 1 via a rounded edge.

Fig. 3 shows, schematically, a second embodiment of a premix gas burner deck plate 1 according to the first aspect of the invention. Fig. 4 shows, schematically, a cross section of the premix gas burner deck plate 1 according to fig. 3, along line A-A of fig. 3.

The embodiment of fig. 3 and fig. 4 is similar to the first embodiment as shown in fig. 1 and fig. 2, but has some additional features.

Like in the embodiment of fig.1 and fig. 2, the premix gas burner deck plate of fig. 3 and fig. 4 has a distribution chamber side 2 and a combustion zone side 3. The distribution chamber side 2 and combustion zone side 3 are located on opposite sides of the premix gas burner deck plate 1. When the premix gas burner deck plate 1 is arranged in a premix gas burner, the distribution chamber side 2 of the premix gas burner deck plate 1 faces towards a gas distribution chamber of the premix gas burner, so, in upstream direction of the flow of the premix gas. When the premix gas burner deck plate 1 is arranged in a premix gas burner, the combustion zone side 3 of the premix gas burner deck plate faces towards a combustion zone in which the actual combustion of the premix gas takes place, so, in downstream direction of the flow of the premix gas.

The premix gas burner deck plate according to fig. 3 and fig. 4 comprises a plurality of gas passage areas 10 and a heat transfer area 5. All the recesses shown in fig. 3 are gas passage areas 10. Premix gas passes from the distribution chamber side 2 of the premix gas burner deck plate 1 to the combustion zone side 3 of the premix gas burner deck plate 1 via the gas passage areas 10. The heat transfer area 5 is designed for effective heat transfer, with the aim of avoiding high burner deck temperatures in the premix gas burner deck plate Iduring use.

The premix gas burner deck plate 1 has a first plate thickness 11 in the gas passage area and a second plate thickness 6 in the heat transfer area 5. The second plate thickness 6 is larger than the first plate thickness 11.

In the embodiment of fig.3 and fig. 4, the premix gas burner deck plate 1 comprises a plurality of gas outflow channels 12, each of which is adapted to during use supply premix gas to the combustion zone, in which combustion zone the combustion of the premix gas takes place during use of the premix gas burner deck plate 1 in a premix gas burner. The combustion zone is usually present adjacent to but just outside of the premix gas burner in which the premix gas burner deck plate is arranged. The gas outflow channels 12 are arranged in the gas passage area 10 and extend through the first plate thickness 11 from the distribution chamber side 2 of the premix gas burner deck plate 1 to the combustion zone side 3 of the premix gas burner deck plate 1.

In the embodiment of fig.3 and fig. 4 each gas passage area 10 comprises a plurality of gas outflow channels 12. The gas outflow channels 12 in each gas passage area 10 are arranged in a predetermined pattern that allows for or is even optimized for the combustion of a premix gas in which the fuel gas is or contains hydrogen

In the embodiment of fig. 3 and fig. 4, the premix gas burner deck plate 1 is made of cast aluminium, e.g. pressure die cast aluminium (including high pressure die cast aluminium) or sand cast aluminium.

In the embodiment of fig. 3 and 4, all gas passage areas 10 are arranged in a central gas discharge zone 13, which is arranged at a distance from a circumferential edge 7 of the premix gas burner deck plate 1 , in this case in the center of the premix gas burner deck plate

In the embodiment of fig. 3 and 4, the premix gas burner deck plate 1 comprises a plate rim area 15 adjacent to at least a part of the circumferential edge 7. In this embodiment the premix gas burner deck plate 1 has a third plate thickness 16 in the plate rim area 15, which third plate thickness 16 is larger than the first plate thickness 11 , and in this embodiment also larger than the second plate thickness 6.

Optionally, the third plate thickness 16 varies over the plate rim area 15, so different parts of the plate rim area 15 have a different thickness. In the embodiment of fig. 3 and fig. 4, the plate rim area 15 extends along the entire circumference of the premix gas burner deck plate. The gas passage areas 10 are arranged in the central gas discharge zone 13 and are surrounded by the plate rim area 15.

In the embodiment of fig. 3 and fig. 4, a passage rim area 17 is provided around each of the gas passage areas 10, and the premix gas burner deck plate has a fourth plate thickness in the passage rim area 17. The fourth plate thickness is larger than the first plate thickness 11 , and in the embodiment of fig. 3 and fig. 4, also larger than the second plate thickness 6. In the embodiment of fig. 3 and fig. 4, the fourth plate thickness is equal to the third plate thickness 16.

Optionally, the fourth plate thickness varies over the passage rim area, so different parts of the passage rim area have a different thickness.

In the embodiment of fig. 3 and fig. 4, the combustion zone side of the premix gas burner deck plate 1 is planar. So, in this embodiment, the combustion zone side 3 of the premix gas burner deck plate 1 is devoid of protrusions and indents.

In the embodiment of fig. 3 and fig. 4, optionally at least the heat transfer area 5 and the gas passage areas 10 of the premix gas burner deck plate 1 are manufactured by a pressure die casting process, for example a high pressure die casting process.

Optionally, in the embodiment of fig.3 and fig. 4, the premix gas burner deck plate 1 is at least partly provided with a coating, e.g. an anti-corrosion coating. For example, a coating is used which provides protection against sulphur induced corrosion and/or corrosion due to the presence of nitric acid. Optionally, a surface roughness is provided on the premix gas burner deck plate prior to applying the coating, e.g. during the pressure die casting process. In the embodiment of fig. 3 and fig. 4, each of the gas outflow channels 12 has a longitudinal axis and, the longitudinal axes of all gas outflow channels 12 are parallel to each other.

In the embodiment of fig. 3 and fig. 4, optionally all gas outflow channels 12 each have an inner wall and the gas passage area 10 has an outer surface at the distribution chamber side of the premix gas burner deck plate, and the inner wall of each gas outflow channel 12 meets the outer surface of the gas passage area 10 at the distribution chamber side of the premix gas burner deck plate 1 via a rounded edge.

Fig. 5 shows, schematically, an example of a design of a gas passage area 10 as can be used in a premix gas burner deck plate 1 according to the first aspect of the invention, e.g. in the first embodiment of fig. 1 and fig. 2 or in the second embodiment of fig. 3 and fig. 4, or in a premix gas burner deck plate according to the second aspect of the invention.

In the example of fig. 5, the gas passage 10 comprises multiple gas outflow channels 12 which are arranged in a predefined pattern.

In the example of fig. 5, the gas outflow channels 12 all have a circular cross-sectional shape, with a diameter that varies over the length of the gas outflow channel 12. In this example, the gas outflow channel 12 is tapered. The taper angle of the gas outflow channel is optionally at least 6°, for example at least 9°, optionally at least 12°. The diameter at an end of the gas outflow channel 12, e.g. at the end with the smallest diameter, is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm.

Optionally, the gas passage area 10 of fig. 5 is part of a premix gas burner deck plate which is manufactured by the method according to the first aspect of the invention, and the gas outflow channels 12 are all formed during the pressure die casting process.

Optionally, in the manufacturing method after the pressure die casting, the local diameter of the gas outflow channels 12 at the distribution chamber side and/or of the combustion chamber side of the premix gas burner deck plate 1 is tuned by removing material from the premix gas burner deck plate adjacent to the tapered gas outflow channel, as is for example indicated by lines a and b in fig. 5. Lines a and b in fig. 5 relate to removal of the material from the combustion zone side. The material can for example be removed by machining.

Due to the tapered shape of the gas outflow channels 12, by removing a small amount of material adjacent to the tapered gas outflow channel 12, the diameter of the opening of the gas outflow channel in the outer surface of the gas passage is increased somewhat. This way, the pressure drop over the gas outflow channels 12 can be finetuned, in particular if material is removed from the end of the gas outflow channel that has the smallest diameter. In the example of fig. 5, this is on the combustion zone side of the premix gas burner deck plate.

Fig. 6 shows, schematically, a first embodiment of a premix gas burner 20 according to the first aspect of the invention. This premix gas burner 20 comprises a premix gas burner deck plate 1 according to the first aspect of the invention, for example a premix gas burner deck plate according to fig. 1 and fig. 2 or according to fig. 3 and fig. 4.

In the embodiment of fig. 6, the premix gas burner 20 comprises a gas distribution chamber 21 , which gas distribution chamber 21 is at least partly delimited by the premix gas burner deck plate 1.

In the embodiment of fig. 6, the premix gas burner 20 further comprises a premix gas supply 23 which is adapted to supply premix gas to the gas distribution chamber 21.

From the gas distribution chamber, the premix gas flows through the gas outflow channel(s) of the premix gas burner deck plate to the combustion zone, where the combustion of the premix gas takes place. The arrows in fig. 6 indicate the direction of the gas flow through the premix gas burner 20.

Optionally, a gas distributor 22 is arranged in the gas distribution chamber 21 , in order to equally distribute the premix gas over multiple gas outflow channels of the premix gas burner deck plate.

Fig. 7 shows, schematically, a further embodiment of a premix gas burner deck plate according to the invention, in which the first aspect of the invention and second aspect of the invention are combined. Fig. 8 shows, schematically, a cross section of the premix gas burner deck plate according to fig. 7, along line A-A of fig. 7.

The premix gas burner deck plate of fig. 7 and fig. 8 has a distribution chamber side 2 and a combustion zone side 3. The distribution chamber side 2 and combustion zone side 3 are located on opposite sides of the premix gas burner deck plate 1. When the premix gas burner deck plate 1 is arranged in a premix gas burner, the distribution chamber side 2 of the premix gas burner deck plate 1 faces towards a gas distribution chamber of the premix gas burner, so, in upstream direction of the flow of the premix gas. When the premix gas burner deck plate 1 is arranged in a premix gas burner, the combustion zone side 3 of the premix gas burner deck plate faces towards a combustion zone in which the actual combustion of the premix gas takes place, so, in downstream direction of the flow of the premix gas. The premix gas burner deck plate according to fig. 7 and fig. 8 comprises a plurality of gas passage areas 10 and a heat transfer area 5. All the recesses shown in fig. 7 are gas passage areas 10. All gas passage areas 10 are arranged in gas discharge zone 13. Premix gas passes from the distribution chamber side 2 of the premix gas burner deck plate 1 to the combustion zone side 3 of the premix gas burner deck plate 1 via the gas passage areas 10. The heat transfer area 5 is designed for effective heat transfer, with the aim of avoiding high burner deck temperatures in the premix gas burner deck plate 1 during use.

The premix gas burner deck plate 1 has a first plate thickness 11 in the gas passage area. The second plate thickness, in the heat transfer area 5, varies and is smaller at the center 13a than at the edge 13b of gas discharge zone 13. The first plate thickness 11 is smaller than the local thickness of the gas discharge zone 13 in an associated part of the heat transfer area 5 that is arranged adjacent to and extends at least partly around each individual gas passage area 10. For example, the first plate thickness is 0.5 millimeters (mm) up to and including 1.5 millimeters (mm), for example 1 millimeter (mm).

In the embodiment of fig. 7 and fig. 8, the premix gas burner deck plate 1 comprises a plurality of gas outflow channels 12, each of which is adapted to during use supply premix gas to the combustion zone, in which combustion zone the combustion of the premix gas takes place during use of the premix gas burner deck plate 1 in a premix gas burner. The combustion zone is usually present adjacent to but just outside of the premix gas burner in which the premix gas burner deck plate is arranged. The gas outflow channels 12 are arranged in the gas passage area 10 and extend through the first plate thickness 11 from the distribution chamber side 2 of the premix gas burner deck plate 1 to the combustion zone side 3 of the premix gas burner deck plate 1.

In the embodiment of fig. 7 and fig. 8, each gas passage area 10 comprises a plurality of gas outflow channels 12. The gas outflow channels 12 in each gas passage area 10 are arranged in a predetermined pattern that allows for or is even optimized for the combustion of a premix gas in which the fuel gas is or contains hydrogen

For example, the gas outflow channels 12 all have a circular cross-sectional shape, with a diameter that is either constant or varies over the length of the gas outflow channel 12. In case the diameter varies over the length of the gas outflow channel 12, the gas outflow channel 12 is for example tapered. The taper angle of the gas outflow channel is optionally at least 6°, for example at least 9°, optionally at least 12°. The diameter at an end of the gas outflow channel 12, e.g. at the end with the smallest diameter, is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm. In case the diameter is constant over the length of the gas outflow channel 12, the diameter at an end of the gas outflow channel 12 is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm. In the embodiment of fig. 7 and fig. 8, the premix gas burner deck plate 1 is made of cast aluminium, e.g. pressure die cast aluminium (including high pressure die cast aluminium) or sand cast aluminium. Cast aluminium has a high thermal conductivity, which makes that it is effective in transferring heat away from the premix gas burner deck plate.

Examples of (aluminium) materials that are suitable for use in the premix burner deck plate 1 according to the embodiment of fig. 7 and fig. 8, are EN-AC44300 (EN AC-AISi12(Fe), Werkstoff no. 3.2582), EN-AC 42100 (EN AC Si7Mg0.3, Werkstoff no. 3.2371 , LM25), EN- AC43000 (EN AC-AL Si10Mg(a), Werkstoff no. 3.2381).

In the embodiment of fig. 7 and fig. 8, the combustion zone side of the premix gas burner deck plate 1 is planar. So, in this embodiment, the combustion zone side 3 of the premix gas burner deck plate 1 is devoid of protrusions and indents.

In the embodiment of fig. 7 and fig. 8, optionally at least the heat transfer area 5 and the gas passage areas 10 of the premix gas burner deck plate 1 are manufactured by a pressure die casting process, for example a high pressure die casting process.

Optionally, in the embodiment of fig. 7 and fig. 8, the premix gas burner deck plate 1 is at least partly provided with a coating, e.g. an anti-corrosion coating. For example, a coating is used which provides protection against sulphur induced corrosion and/or corrosion due to the presence of nitric acid. Optionally, a surface roughness is provided on the premix gas burner deck plate prior to applying the coating, e.g. during the pressure die casting process.

As can be seen in fig. 8, in this embodiment, each of the gas outflow channels has a longitudinal axis and the longitudinal axes of all gas outflow channels 12 are parallel to each other.

In the embodiment of fig. 7 and fig. 8, optionally all gas outflow channels 12 each have an inner wall and the gas passage area 10 has an outer surface at the distribution chamber side of the premix gas burner deck plate, and the inner wall of each gas outflow channel 12 meets the outer surface of the gas passage area 10 at the distribution chamber side of the premix gas burner deck plate 1 via a rounded edge.

In the embodiment of fig. 7 and fig. 8, the thickness of the gas discharge zone 13 changes continuously from the center 13a of the gas discharge zone 13 to the edge 13b of the gas discharge zone 13b. In this example, the gas discharge zone 13 has a concave shape on the distribution chamber side, and indentations are provided in the cross-sectional shape of the gas discharge zone 13 at the location of the gas passage areas 10, on the distribution chamber side. Alternatively or in addition, a concave shape may be provided on the combustion zone side.

In the embodiment of fig. 7 and fig. 8, the premix gas burner deck plate 1 comprises a plate rim area 15 adjacent to at least a part of the circumferential edge 7. In this embodiment the premix gas burner deck plate 1 has a third plate thickness 16 in the plate rim area 15. In this embodiment, the third plate thickness is larger than the first plate thickness, and for example equal to a maximum thickness of the gas discharge zone.

Fig. 9 shows, schematically, an embodiment of a premix gas burner deck plate according to the second aspect of the invention. Fig. 10 shows, schematically, a cross section of the premix gas burner deck plate according to fig. 9, along line A-A of fig. 9.

The premix gas burner deck plate of fig. 9 and fig. 10 has a distribution chamber side 2 and a combustion zone side 3. The distribution chamber side 2 and combustion zone side 3 are located on opposite sides of the premix gas burner deck plate 1. When the premix gas burner deck plate 1 is arranged in a premix gas burner, the distribution chamber side 2 of the premix gas burner deck plate 1 faces towards a gas distribution chamber of the premix gas burner, so, in upstream direction of the flow of the premix gas. When the premix gas burner deck plate 1 is arranged in a premix gas burner, the combustion zone side 3 of the premix gas burner deck plate faces towards a combustion zone in which the actual combustion of the premix gas takes place, so, in downstream direction of the flow of the premix gas.

The premix gas burner deck plate according to fig. 9 and fig. 10 comprises a plurality of gas passage areas 10 and a heat transfer area 5. All gas passage areas 10 are arranged in gas discharge zone 13. Premix gas passes from the distribution chamber side 2 of the premix gas burner deck plate 1 to the combustion zone side 3 of the premix gas burner deck plate 1 via the gas passage areas 10. The heat transfer area 5 is designed for effective heat transfer, with the aim of avoiding high burner deck temperatures in the premix gas burner deck plate 1 during use.

The gas discharge zone 13 has a center 13a and an edge 13b, and a cross-sectional shape having a thickness that is smaller at the center 13a than at the edge 13b.

The gas passages areas 10 are embedded in the heat transfer area 5. At least a part of the heat transfer area 5 is arranged adjacent to and at least partly extends around each individual gas passage area.

In the embodiment of fig. 9 and fig. 10, the premix gas burner deck plate 1 comprises a plurality of gas outflow channels 12, each of which is adapted to during use supply premix gas to the combustion zone, in which combustion zone the combustion of the premix gas takes place during use of the premix gas burner deck plate 1 in a premix gas burner. The combustion zone is usually present adjacent to but just outside of the premix gas burner in which the premix gas burner deck plate is arranged. The gas outflow channels 12 are arranged in the gas passage area 10 and extend through the first plate thickness 11 from the distribution chamber side 2 of the premix gas burner deck plate 1 to the combustion zone side 3 of the premix gas burner deck plate 1.

In the embodiment of fig. 9 and fig. 10, each gas passage area 10 comprises a plurality of gas outflow channels 12. The gas outflow channels 12 in each gas passage area 10 are arranged in a predetermined pattern that allows for or is even optimized for the combustion of a premix gas in which the fuel gas is or contains hydrogen

In the embodiment of fig. 9 and fig. 10, the premix gas burner deck plate 1 is made of cast aluminium, e.g. pressure die cast aluminium (including high pressure die cast aluminium) or sand cast aluminium. Cast aluminium has a high thermal conductivity, which makes that it is effective in transferring heat away from the premix gas burner deck plate.

Examples of (aluminium) materials that are suitable for use in the premix burner deck plate 1 according to the embodiment of fig. 9 and fig. 10, are EN-AC44300 (EN AC- AISi12(Fe), Werkstoff no. 3.2582), EN-AC 42100 (EN AC Si7Mg0.3, Werkstoff no. 3.2371 , LM25), EN-AC43000 (EN AC-AL Si10Mg(a), Werkstoff no. 3.2381).

In the embodiment of fig. 9 and fig. 10, the combustion zone side of the premix gas burner deck plate 1 is planar. So, in this embodiment, the combustion zone side 3 of the premix gas burner deck plate 1 is devoid of protrusions and indents.

In the embodiment of fig. 9 and fig. 10, optionally at least the heat transfer area 5 and the gas passage areas 10 of the premix gas burner deck plate 1 are manufactured by a pressure die casting process, for example a high pressure die casting process.

Optionally, in the embodiment of fig. 9 and fig. 10, the premix gas burner deck plate 1 is at least partly provided with a coating, e.g. an anti-corrosion coating. For example, a coating is used which provides protection against sulphur induced corrosion and/or corrosion due to the presence of nitric acid. Optionally, a surface roughness is provided on the premix gas burner deck plate prior to applying the coating, e.g. during the pressure die casting process.

As can be seen in fig. 10, in this embodiment, each of the gas outflow channels has a longitudinal axis and the longitudinal axes of all gas outflow channels 12 are parallel to each other.

In the embodiment of fig. 9 and fig. 10, optionally all gas outflow channels 12 each have an inner wall and the gas passage area 10 has an outer surface at the distribution chamber side of the premix gas burner deck plate, and the inner wall of each gas outflow channel 12 meets the outer surface of the gas passage area 10 at the distribution chamber side of the premix gas burner deck plate 1 via a rounded edge.

In the embodiment of fig. 9 and fig. 10, the thickness of the gas discharge zone 13 changes continuously from the center 13a of the gas discharge zone 13 to the edge 13b of the gas discharge zone 13b. In this example, the gas discharge zone 13 has a concave shape on the distribution chamber side, and indentations are provided in the cross-sectional shape of the gas discharge zone 13 at the location of the gas passage areas 10, on the distribution chamber side. Alternatively or in addition, a concave shape may be provided on the combustion zone side.

In the embodiment of fig. 9 and fig. 10, the premix gas burner deck plate 1 comprises a plate rim area 15 adjacent to at least a part of the circumferential edge 7. In this embodiment the premix gas burner deck plate 1 has a third plate thickness in the plate rim area 15. In this embodiment, the third plate thickness is larger than the first plate thickness, and for example equal to a maximum thickness of the gas discharge zone.

Fig. 11 shows, schematically, a further example of a design of a gas passage area 10 as can be used in a premix gas burner deck plate 1 according to the first aspect of the invention, e.g. in the first embodiment of fig. 1 and fig. 2 or in the second embodiment of fig. 3 and fig. 4, or in a premix gas burner deck plate according to the second aspect of the invention.

In the example of fig. 11 , the gas passage 10 comprises multiple gas outflow channels 12 which are arranged in a predefined pattern.

In the example of fig. 11 , the gas outflow channels 12 all have a circular cross-sectional shape.

In the example of fig. 11 , the gas outflow channels 12 comprise a first channel portion 12a which extends over a part of the length of the respective gas outflow channel 12, and this first channel portion 12a is tapered.

So, the cross-sectional size of the first channel portion 12a of the gas outflow channels 12 varies over the length of said first channel portion 12a, in such a way that it either increases or decreases from one end of the first channel portion 12a to the other end of the second channel portion 12a. The diameter of the circular cross-section of the first channel portion 12a is larger on one end of the first channel portion 12a than on the other end of the first channel portion 12a.

In the example of fig. 11 , the gas outflow channels 12 further comprise a second channel portion 12b which extends over a part of the length of the respective gas outflow channel 12. In this example, the first channel portion 12a has a circular cross section and the second channel portion 12b also has a circular cross section. The second channel portion 12b has a constant diameter. In this example the first channel portion 12a and the second channel portion 12b together form the gas outflow channel 12. Optionally, the first channel portion 12a of the gas outflow channel 12 widens from the combustion zone side of the premix gas burner deck plate towards the distribution chamber side of the premix gas burner deck plate, and the second channel portion 12b of the same gas outflow channel, which second channel portion has a constant diameter, is located closer to the combustion zone side of the premix gas burner deck than to the distribution chamber side of the premix gas burner deck plate.

In the example of fig. 11 , the diameter of the second channel portion 12b is the same as the smallest diameter of the first channel portion 12a.

In the example of fig. 11 , the premix gas burner deck plate comprises a plurality of gas outflow channels 12, and multiple gas outflow channels 12 of the plurality of gas outflow channels are tapered over a part of their length. Optionally, all gas outflow channels 12 of the plurality of gas outflow channels are tapered over a part of their length.

The taper angle of the first channel portion12a is optionally at least 6°, for example at least 9°, optionally at least 12°. The diameter at an end of the first channel portion 12a, e.g. at the end with the smallest diameter, is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm. The diameter of the second channel portion 12b is for example 0.6 mm - 1.0 mm, e.g. 0.8 mm.

Optionally, the gas passage area 10 of fig. 11 is part of a premix gas burner deck plate which is manufactured by the method according to the first aspect of the invention, and the gas outflow channels 12 are all formed during the pressure die casting process.

Fig. 12 shows, schematically, a portion of a further embodiment of a premix gas burner deck plate according to the first aspect of the invention. Fig. 13 shows, schematically, a cross-section along line B-B of the embodiment of fig. 12.

The premix gas burner deck plate according to fig. 12 and fig. 13 comprises a plurality of gas passage areas 10 and a heat transfer area 5. In the gas passage areas 10, the premix gas burner deck plate has a first plate thickness 11.

In the embodiment of fig. 12 and fig. 13, the heat transfer area 5 is formed by a closed area which is connected to all gas passage areas 10. The closed area is closed, i.e. it does not comprise a gas passage area and/or a gas outflow channel.

In the embodiment of fig. 12 and fig. 13, the closed are comprises a first first portion 5a1 , a second first portion 5a2 and a plurality of second portions 5b. The pattern of gas passage areas, first first portion 5a1, second first portion 5a2 and second portions 5b is repeated over the surface of the premix gas burner deck plate.

In the embodiment of fig. 12 and fig. 13, a passage rim area 17 is provided around each of the gas passage areas 10. Optionally, as is shown in fig. 12, the passage rim area 17 encircles multiple, e.g. three, gas passage areas 10. The first portions 5a1, 5a2 of the closed area are connected to the gas passage areas 10 via the passage rim area 17.

In the embodiment of fig. 12 and fig. 13, the first portions 5a1, 5a2 and the second portions 5b have a different plate thickness. The plate thickness of the multiple second portions 5b is mutually the same, but the plate thickness 6a1 of the first first portion 5a1 is different from the plate thickness 6a2 of the second first portion 5a2. In addition, also the width of the first first portion 5a1 is different from the width of the second first portion 5a2. Design parameters such as plate thickness of the first portions 5a1, 5a2 and of second portions 5b and the width of the first portions 5a1, 5a2 and second portions 5b allow to optimize the heat transfer out of the premix gas burner deck plate.

In the embodiment of fig. 12 and fig. 13, the plate thickness 6a1, 6a2 of the first portions 5a1 , 5a2 of the closed area, the plate thickness 6b of the second portions 5b of the closed area and the plate thickness of the passage rim area 17 are all larger than the first plate thickness 11. The plate thickness 6b of the second portions 5b of the closed area is larger than the first plate thickness 11 , but smaller than the second plate thickness 6a1 , i.e. the smallest of the plate thicknesses 6a1, 6a2 of the first portions 5a1, 5a2 of the closed area. The first first portion 5a1 of the closed has a plate thickness equal to the second plate thickness 6a1, and the plate thickness 6a2 in the second first portion 5a2 of the closed area is larger than the second plate thickness 6a1. The plate thickness of passage rim area 17, i.e. the fourth plate thickness, is larger than all of the first plate thickness 11, the plate thicknesses 6a1, 6a2 of the first portions 5a1, 5a2 of the closed are and the plate thickness 6b of the second portions 5b of the closed area.

Claims

1. Premix gas burner deck plate, which premix gas burner deck plate has a distribution chamber side and a combustion zone side, which distribution chamber side and combustion zone side are located on opposite sides of the premix gas burner deck plate, which premix gas burner deck plate further comprises:

- a gas passage area, and

- a heat transfer area, wherein the premix gas burner deck plate has a first plate thickness in the gas passage area and a second plate thickness in the heat transfer area, which second plate thickness is larger than the first plate thickness, and wherein the premix gas burner deck plate comprises a gas outflow channel which is adapted to during use supply premix gas to a combustion zone, which gas outflow channel is arranged in the gas passage area and extends through the first plate thickness from the distribution chamber side of the premix gas burner deck plate to the combustion zone side of the premix gas burner deck plate, and wherein the premix gas burner deck plate is made of cast aluminium.

2. Premix gas burner deck plate according to claim 1, wherein the gas passage area comprises a plurality of gas outflow channels.

3. Premix gas burner deck plate according to any of the preceding claims, wherein the premix gas burner deck plate comprises a plurality of gas passage areas, and each gas passage area comprises at least one gas outflow channel.

4. Premix gas burner deck plate according to any of the preceding claims, wherein the premix gas burner deck plate has a circumferential edge, and wherein the premix gas burner deck plate comprises a plate rim area adjacent to at least a part of the circumferential edge, and wherein the premix gas burner deck plate has a third plate thickness in the plate rim area, wherein the third plate thickness is larger than the first plate thickness, optionally equal to or larger than the second plate thickness.

5. Premix gas burner deck plate according to any of the preceding claims, wherein at least one gas outflow channel is tapered or wherein the gas outflow channel comprises a first channel portion which extends over a part of the length of said gas outflow channel, and said first channel portion is tapered.

6. Premix gas burner deck plate according to any of the preceding claims, wherein a passage rim area is provided around at least one gas passage area, and wherein the premix gas burner deck plate has a fourth plate thickness in the passage rim area, wherein the fourth plate thickness is larger than the first plate thickness, optionally equal to or larger than the second plate thickness.

7. Premix gas burner deck plate according to any of the preceding claims, wherein the combustion zone side of the premix gas burner deck plate is planar.

8. Premix gas burner deck plate according to any of the preceding claims, wherein at least the heat transfer area and/or the gas passage area of the premix gas burner deck plate are manufactured by a pressure die casting process.

9. Premix gas burner deck plate according to claim 8, wherein further the gas outflow channel of the premix gas burner deck plate is formed in the pressure die casting process.

10. Premix gas burner deck plate according to claim 3, wherein multiple gas passage areas are arranged in a gas discharge zone, and wherein the premix gas burner deck plate further has a circumferential edge, and wherein the premix gas burner deck plate further comprises a plate rim area adjacent to at least a part of the circumferential edge and at least partly surrounding the gas discharge zone, and wherein the premix gas burner deck plate has a third plate thickness in the plate rim area, wherein the third plate thickness is larger than the first plate thickness, optionally equal to or larger than the second plate thickness.

11. Premix gas burner deck plate according to any of the preceding claims, wherein the premix gas burner deck plate is at least partly provided with a coating, e.g. an anti-corrosion coating, wherein optionally the coating is present at least on a part of the combustion zone side of the premix gas burner deck plate and/or on an inner wall of the gas outflow channel.

12. Premix gas burner deck plate according to any of the preceding claims, wherein the premix gas burner deck plate comprises a curved portion having a radius of curvature, and wherein multiple gas outflow channels are provided in the curved portion, each of the gas outflow channels in the curved portion having a longitudinal axis, and wherein the longitudinal axes of all gas outflow channels in the curved portion are parallel to each other.

13. Premix gas burner deck plate according to any of the preceding claims, wherein the gas outflow channel has an inner wall and the gas passage area has an outer surface at the distribution chamber side of the premix gas burner deck plate, and wherein the inner wall of the gas outflow channel meets the outer surface of the gas passage area at the distribution chamber side of the premix gas burner deck plate via a rounded edge.

14. Premix gas burner deck plate, which premix gas burner deck plate has a distribution chamber side and a combustion zone side, which distribution chamber side and combustion zone side are located on opposite sides of the premix gas burner deck plate, which premix gas burner deck plate further comprises a gas discharge zone, which gas discharge zone has a center and an edge, and a cross-sectional shape having a thickness that is smaller at the center than at the edge, wherein the gas discharge zone comprises:

15. Premix gas burner comprising a premix gas burner deck plate according to any of the preceding claims.

16. Premix gas burner according to claim 15, wherein the premix gas burner comprises a gas distribution chamber, and wherein the gas distribution chamber is at least partly delimited by the premix gas burner deck plate.

17. Premix gas burner according to any of the claims 15-16, wherein the premix gas burner deck plate is a premix gas burner deck plate according to claim 10 or to claim 14, and wherein the premix gas burner deck plate is mounted into the premix gas burner in such a way that during use the gas discharge zone is subjected to compression stress.

18. Premix gas burner according to claim 17, wherein the plate rim area of the premix gas burner deck plate is in thermal contact with a heat sink.

19. Premix gas burner according to any of the claims 15 - 18, wherein the premix gas burner comprises a mounting flange which allows to mount the premix gas burner to a heat exchanger, which mounting flange is designed to allow heat transfer from the premix gas burner to the heat exchanger.

20. Heating appliance comprising the premix gas burner according to any of the claims 15-19 and a heat exchanger, wherein optionally the premix gas burner deck plate of the premix gas burner is in thermal contact with the heat exchanger, and/or wherein optionally the premix gas burner and the heat exchanger are made of the same material and/or wherein optionally the premix gas burner and the heat exchanger are integral with each other, e.g. in the form of an integrally cast aluminium element.

21 . Method for manufacturing a premix gas burner deck plate according to any of the claims 1-14, which method comprises:

- pressure die casting the premix gas burner deck plate in a die, wherein the gas passage area and the gas outflow channel are formed in the die.

22. Method according to claim 21 , wherein a tapered gas outflow channel is formed in the die during the pressure die casting, and/or wherein a gas outflow channel is formed in the die during the pressure die casting which gas outflow channel comprises a first channel portion, which first channel portion is tapered.

23. Method according to claim 22, wherein the method further comprises the step of: after the pressure die casting, tuning a local diameter of a gas outflow channel by removing material from the premix gas burner deck plate adjacent to the tapered gas outflow channel.

24. Method according to any of the claims 21-23, wherein the method further comprises the step of: after the pressure die casting, applying a coating to at least a part of the premix gas burner deck plate, wherein optionally the coating is applied at least on a part of the combustion zone side of the premix gas burner deck plate and/or on an inner wall of the gas outflow channel.