A burner assembly with an air-gas mixing unit and a burning unit

Abstract

A burner assembly 100 has an air-gas mixing unit 110 for mixing of air and a combustible gas to form an air-gas mixture 115, and a burning unit 120 for combustion of the air-gas mixture. The air-gas mixing unit and the burning unit are interconnected to form a gas-tight pathway 210 that in use guides the air-gas mixture from the air-gas mixing unit to the burning unit. The gas-tight pathway is adjustable from a first flow path length 212 for use with a first type of gas to a second flow path length 214 for use with a second type of gas. The first type of gas may be hydrogen gas and the second type of gas may be methane. A flow diverter 230 may be used, such as a moveable flap (400 Fig. 4), (500 Fig. 5), and can be moved from a first position to a second position to select either the first low path length or the second flow path length. The arrangement allows the burner assembly to be used in a combustion appliance that can operate on a range of gases and reduces the risk and severity of flashback.

Description

Description Title A burner assembly with an air-qas mixing unit and a burning unit Background of the Invention The present invention relates to a burner assembly comprising an air-gas mixing unit for mixing of air and gas to form an air-gas mixture, and a burning unit for combustion of the air-gas mixture, wherein the air-gas mixing unit and the burn- ing unit are interconnected to form a gas-tight pathway that is adapted for guiding the air-gas mixture from the air-gas mixing unit to the burning unit. Furthermore, the present invention relates to an air-gas mixture burning appliance comprising such a burner assembly. From the state of the art an air-gas mixture burning appliance with a burner as- sembly that comprises an air-gas mixing unit for mixing of air and gas to form an air-gas mixture, as well as a burning unit for combustion of the air-gas mixture, is known. For guiding the air-gas mixture from the air-gas mixing unit to the burning unit, both units are interconnected to form a gas-tight pathway. Furthermore, the air-gas mixing unit and, more generally, the burner assembly can be embodied to operate on different gases, e.g. on hydrogen gas or on hydrocarbon gas, such as methane. Summary of the Invention The present invention relates to a burner assembly comprising an air-gas mixing unit for mixing of air and gas to form an air-gas mixture, and a burning unit for combustion of the air-gas mixture. The air-gas mixing unit and the burning unit are interconnected to form a gas-tight pathway that is adapted for guiding the air- gas mixture from the air-gas mixing unit to the burning unit. The gas-tight path- way is adjustable from a first flow path length adapted for use with a first type of gas to a second flow path length adapted for use with a second type of gas. Pref- erably, the first flow path length is different from the second flow path length. Advantageously, by enabling adjustment of a given flow path length in the burner assembly between the air-gas mixing unit and the burning unit dependent on the used type of gas, a respective volume of air-gas mixture upstream of the burning unit may be adjusted without changing an underlying positioning of the air-gas mixing unit relative to the burning unit. More specifically, if the air-gas mixture is e.g. an air-methane mixture, a suitable mixing of the air and methane for com- plete combustion may usually not be achieved if the flow path length is too small. In contrast, if the air-gas mixture is e.g. an air-hydrogen mixture, a respective risk and possible severity of occurrence of a flashback may increase if the flow path length is too great. Such a flashback is an event where an air-hydrogen mixture flame may propagate upstream of the burning unit causing combustion of the air- hydrogen mixture in unintended locations upstream of the burning unit, which can be extremely damaging to the burner assembly if the flame is allowed to acceler- ate into detonation, where large overpressures are witnessed. As a conse- quence, by means of a suitable adjustment of the given flow path length, the lat- ter may e.g. be increased if the burner assembly is used with an air-methane mix- ture to enable complete combustion of the air-methane mixture, and it may be re- duced if the burner assembly is used with an air-hydrogen mixture to reduce a re- spective risk and possible severity of occurrence of a flashback. Preferably, the second flow path length is at least 25% greater than the first flow path length. Preferentially, the second flow path length is at most four times greater than the first flow path length. Thus, the flow path length may advantageously be adjusted either to a value that is suitable to achieve complete combustion if the air-gas mixture is e.g. an air- methane mixture, or to a value that is suitable to prevent a flashback if the air-gas mixture is e.g. an air-hydrogen mixture. According to some aspects, the burner assembly further comprises an adjust- ment mechanism that is configured for adjusting the gas-tight pathway from the first flow path length to the second flow path length. Thus, adjustment of a given flow path length in the burner assembly between the air-gas mixing unit and the burning unit may easily and reliably be achieved. Preferably, the adjustment mechanism comprises at least one flow diverter that is arranged in the gas-tight pathway for diverting the air-gas mixture from a first flow path having the first flow path length toward a second flow path having the sec- ond flow path length. Thus, a robust and stable adjustment mechanism may be provided. Preferably, the at least one flow diverter is movable in the gas-tight pathway be- tween a first position associated with the first flow path and a second position as- sociated with the second flow path. Thus, the at least one flow diverter enables an easy and quick adjustment of the flow path length. Preferably, the at least one flow diverter is slidably or rotatably arranged in the gas-tight pathway. Thus, an uncomplicated and precise operation of the at least one flow diverter is enabled. Preferably, the adjustment mechanism comprises a movable flap that is movable in the gas-tight pathway between a first position associated with the first flow path and a second position associated with the second flow path, wherein the mova- ble flap is adapted for interacting with the at least one flow diverter for adjusting the gas-tight pathway from the first flow path length to the second flow path length. Thus, a configuration is enabled wherein the at least one flow diverter is static and wherein only the movable flap is movable between at least two different posi- tions. Preferably, the movable flap is slidably or rotatably arranged in the gas-tight path- way. Thus, an uncomplicated and precise operation of the movable flap is enabled. Preferably, the movable flap is movably mounted to the air-gas mixing unit. Thus, the movable flap may securely and reliably be mounted to the burner as- sembly in the gas-tight pathway. Preferably, the burner assembly further comprises an operating element that is operable for moving the at least one flow diverter or the movable flap between the first and second positions. Thus, the at least one flow diverter or the movable flap may easily and precisely be operated. The at least one flow diverter may be attached to, or integrally formed with, the air-gas mixing unit. Thus, a robust and stable mounting of the at least one flow diverter to the air-gas mixing unit is enabled. Alternatively, the at least one flow diverter may be attached to, or integrally formed with, the burning unit. Thus, a robust and stable mounting of the at least one flow diverter to the burning unit is enabled. According to some aspects, the first type of gas comprises hydrogen gas, and the second type of gas comprises hydrocarbon gas, in particular methane. Thus, the burner assembly may advantageously be used with the two most widely used types of gases. According to some aspects, the burning unit forms a semi-cylindrical burning area or a cylindrical burning area. Thus, different types and shapes of burning units may be used in the burner as- sembly. Furthermore, the present invention relates to an air-gas mixture burning appli- ance comprising a burner assembly as described above. Thus, a reliable and secure air-gas mixture burning appliance may be provided. Brief Description of the Drawings Exemplary embodiments of the present invention are described in detail hereinaf- ter with reference to the attached drawings. In these attached drawings, identical or identically functioning components and elements are labelled with identical ref- erence signs and they are generally only described once in the following descrip- tion. Fig. 1 shows a schematic view of a burner assembly with an air-gas mixing unit and a burning unit according to the present invention, Fig. 2 shows a schematic view of the burner assembly of Fig. 1 with an adjust- ment mechanism according to a first illustrative realization, Fig. 3 shows a schematic view of the burner assembly of Fig. 1 with an adjust- ment mechanism according to a second illustrative realization, Fig. 4 shows a schematic view of the burner assembly of Fig. 1 with an adjust- ment mechanism according to a third illustrative realization, Fig. 5 shows a schematic view of the burner assembly of Fig. 1 with an adjust- ment mechanism according to a fourth illustrative realization, Fig. 6 shows a schematic view of the burner assembly of Fig. 1 with an adjust- ment mechanism according to a fifth illustrative realization, Fig. 7 shows a schematic view of the burner assembly of Fig. 1 with an adjust- ment mechanism according to a sixth illustrative realization, Fig. 8 shows a schematic view of the burner assembly of Fig. 1 with an adjust- ment mechanism according to a seventh illustrative realization, Fig. 9 shows a schematic view of the burner assembly of Fig. 1 with an adjust- ment mechanism according to an eighth illustrative realization, Fig. 10 shows a schematic view of the burner assembly of Fig. 1 with an adjust- ment mechanism according to a ninth illustrative realization, Fig. 11 shows a schematic view of the burner assembly of Fig. 1 with an adjust- ment mechanism according to a tenth illustrative realization, and Fig. 12 shows a schematic view of the burner assembly of Fig. 1 with an adjust- ment mechanism according to an eleventh illustrative realization. Detailed Description Fig. 1 shows an illustrative burner assembly 100 for combustion of an air-gas mixture 115, with an air-gas mixing unit 110 and a burning unit 120. The air-gas mixing unit 110 is preferably adapted for mixing of air and gas to form the air-gas mixture 115. Preferentially, the air-gas mixture 115 is a homogenous mixture of air and gas. By way of example, the burning unit 120 may comprise a perforated metal plate where the air-gas mixture 115 is ignited for combustion. Preferably, the burner assembly 100 is convertible and may at least be used with two different types of gas. A first type of gas may e.g. comprise hydrogen gas and a second type of gas may e.g. comprise hydrocarbon gas, such as methane. By way of example, the burner assembly 100 may be used in an associated air- gas mixture burning appliance. More particularly, the burner assembly 100 is preferably at least adapted for use in domestic appliances up to 70 kW. Fig. 2 shows in part (A) and part (B) the burner assembly 100 of Fig. 1 with the air-gas mixing unit 110 that is provided for mixing of air and gas to form the air- gas mixture 115, and the burning unit 120 for combustion of the air-gas mixture 115. By way of example, the air-gas mixing unit 110 comprises a Venturi-type mixing nozzle 112. lllustratively, the air-gas mixing unit 110 and the burning unit 120 are intercon- nected to form a gas-tight pathway 210 that is adapted for guiding the air-gas mixture 115 from the air-gas mixing unit 110 to the burning unit 120. Preferably, the gas-tight pathway 210 is adjustable from a first flow path length adapted for use with a first type of gas to a second flow path length adapted for use with a second type of gas. Preferentially, the first flow path length is different from the second flow path length. Preferably, the second flow path length is at least 25% greater than the first flow path length. However, preferentially the second flow path length is at most four times greater than the first flow path length. Nevertheless, it should be noted that a respective upper limit of the second flow path length generally depends on fac- tors such as space constraints, manufacturing constraints, and costs. It should be noted that in the context of the present invention the expression “flow path length” refers to the length of a respective path along which the air-gas mix- ture 115 flows between the air-gas mixing unit 110 and the burning unit 120. For instance, it may be considered that the respective path extends between a cross- section of the air-gas mixing unit 110 where the air and the gas come into con- tact, and a cross-section of the burning unit 120 where the air-gas mixture 115 is ignited, i.e. combusted. In this case, it may be assumed that the gas-tight path- way 210 forms a conduit between the cross-section of the air-gas mixing unit 110 where the air and the gas come into contact, and the cross-section of the burning unit 120 where the air-gas mixture 115 is ignited, i.e. combusted, and that the length of the respective path corresponds e.g. to a length of a central axis of the conduit. According to part (A), the gas-tight pathway 210 of the burner assembly 100 has a flow path length 212 that illustratively corresponds to the length of a straight connection line between the air-gas mixing unit 110 and the burning unit 120. The straight connection line forms a flow path 240. By adjusting the gas-tight pathway 210 to the flow path length 212, the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrogen gas. Preferably, the burner assembly 100 is provided with an adjustment mechanism 220 that is configured for adjusting the gas-tight pathway 210 from the flow path length 212 to a flow path length 214 as illustrated in part (B). The adjustment mechanism 220 may comprise one or more and, by way of example, one flow di- verter 230. According to part (B), the gas-tight pathway 210 of the burner assembly 100 has a flow path length 214 that illustratively corresponds to the length of a meander- shaped line between the air-gas mixing unit 110 and the burning unit 120. The meander-shaped line forms a prolongated flow path 250. The flow path 250 is il- lustratively obtained by moving and, more particularly, by gliding the flow diverter 230 in direction of an arrow 232 shown in part (A) until it is positioned according to part (B) in front of the air-gas mixing unit 110. In other words, the flow diverter 230 is preferably movable in the gas-tight pathway 210 between a first position associated with the flow path 240 according to part (A) and a second position as- sociated with the flow path 250 according to part (B). As illustrated in part (B), the flow diverter 230 may be arranged in the gas-tight pathway 210 such that it diverts the air-gas mixture 115 from the flow path 240 having the flow path length 212 according to part (A) toward the flow path 250 having the flow path length 214. By adjusting the gas-tight pathway 210 to the flow path length 214, the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrocarbon gas, in particular methane. Starting with the positioning of the flow diverter 230 in front of the air-gas mixing unit 110 as illustrated in part (B), the flow diverter 230 may illustratively be moved in direction of an arrow 234. This allows to move the flow diverter 230 back into its position illustrated in part (A). Fig. 3 shows in part (A) and part (B) the burner assembly 100 of Fig. 2 with the air-gas mixing unit 110 that is provided for mixing of air and gas to form the air- gas mixture 115, and the burning unit 120 for combustion of the air-gas mixture 115. The air-gas mixing unit 110 comprises the Venturi-type mixing nozzle 112. Furthermore, the air-gas mixing unit 110 and the burning unit 120 are intercon- nected to form the gas-tight pathway 210 that is adjustable from the flow path 240 according to part (A) to the flow path 250 according to part (B). According to part (A), the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrogen gas. The burner assembly 100 has the adjust- ment mechanism 220 which is now in contrast to Fig. 2 provided with a flow di- verter 310 that is attached to, or integrally formed with, the air-gas mixing unit 110. The flow diverter 310 is illustratively arc-shaped in cross section. However, in the configuration according to part (A) the flow diverter 310 is not used for di- verting the air-gas mixture 115 so that the flow path 240 is realized. According to part (B), the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrocarbon gas, in particular methane. In contrast to part (A), the burner assembly 100 is in part (B) further provided with an additional flow diverter 320 of the adjustment mechanism 220 which may e.g. be rotatably at- tached to the air-gas mixing unit 110, or to the burning unit 120. Alternatively, the additional flow diverter 320 may be glidingly mounted to the air-gas mixing unit 110 or the burning unit 120, or it may be mounted to the burner assembly 100 only if required for converting the burner assembly 100. lllustratively, the additional flow diverter 320 of part (B) is arc-shaped in cross section and rotatably attached to the air-gas mixing unit 110. More specifically, the additional flow diverter 320 is rotatable as illustrated with an arrow 327 around a rotation axis 325, which may e.g. be formed by a pin. The additional flow diverter 320 is rotated around the rotation axis 325 into a position associated with the flow path 250, in which the additional flow diverter 320 interacts with the flow diverter 310 to create the flow path 250. By e.g. rotating the additional flow diverter 320 for approximately 180° around the rotation axis 325, it may be ro- tated into a position associated with the flow path 240 of part (A). This corre- sponds to simply entirely removing the additional flow diverter 320 from the burner assembly 100, as illustrated in part (A). Fig. 4 shows in part (A) and part (B) the burner assembly 100 of Fig. 2 with the air-gas mixing unit 110 that is provided for mixing of air and gas to form the air- gas mixture 115, and the burning unit 120 for combustion of the air-gas mixture 115. The air-gas mixing unit 110 comprises the Venturi-type mixing nozzle 112. Furthermore, the burner assembly 100 is provided with the flow diverter 230 of the adjustment mechanism 220, which is illustratively attached to, or integrally formed with, the air-gas mixing unit 110. The air-gas mixing unit 110 and the burning unit 120 are interconnected to form the gas-tight pathway 210 that is ad- justable from the flow path 240 according to part (A), wherein the burner assem- bly 100 is e.g. adapted for use with a type of gas that comprises hydrogen gas, to the flow path 250 according to part (B), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrocarbon gas, in particular methane. In contrast to Fig. 2, the air-gas mixing unit 110 is now illustratively connected via a gas-tight seal 450 to the burning unit 120 to form the gas-tight pathway 210. By way of example, the burning unit 120 has a semi-cylindrical burning area 420. The burning unit 120 may further comprise a frame 125 provided for mounting of the burning unit 120 to the air-gas mixing unit 110. Moreover, the air-gas mixing unit 110 now illustratively forms an air-gas mixture supply channel 118 and is provided with an eccentric extension space 610 that forms a part of the adjust- ment mechanism 220. A boundary of the eccentric extension space 610 is formed by the flow diverter 230. The flow diverter 230 may interact with a mova- ble flap 400, as described hereinafter, which is according to one aspect slidably arranged in the gas-tight pathway 210. According to part (A), the slidable flap 400 is e.g. mounted to an operating ele- ment 410. The operating element 410 is illustratively a pivotable lever with a knob 415, which is mounted pivotally to the air-gas mixing unit 110. Alternatively, the pivotable lever 410 with the knob 415 may be mounted pivotally to the burning unit 120. lllustratively, the slidable flap 400 is in a position associated with the flow path 240. Movement of the knob 415 in a direction illustrated by an arrow 430 pivots the pivotable lever 410 such that the slidable flap 400 is moved in a direction illustrated by an arrow 440. According to part (B), the slidable flap 400 is moved in the direction illustrated by the arrow 440 into a position associated with the flow path 250. In this position, the movable flap 400 closes the flow path 240 of part (A) and interacts with the flow diverter 230 to form the flow path 250. Movement of the slidable flap 400 in a direction opposed to the direction illustrated by the arrow 440 via a suitable movement of the knob 415 enables re-opening of the flow path 240. Fig. 5 shows in part (A) and part (B) the burner assembly 100 of Fig. 4 with the air-gas mixing unit 110 that is provided for mixing of air and gas to form the air- gas mixture 115, and the burning unit 120 for combustion of the air-gas mixture 115. The air-gas mixing unit 110 comprises the Venturi-type mixing nozzle 112. Furthermore, the burner assembly 100 is provided with the flow diverter 230 of the adjustment mechanism 220, which is attached to, or integrally formed with, the air-gas mixing unit 110. The air-gas mixing unit 110 is connected via the gas- tight seal 450 to the burning unit 120 to form the gas-tight pathway 210 that is ad- justable from the flow path 240 according to part (A), wherein the burner assem- bly 100 is e.g. adapted for use with a type of gas that comprises hydrogen gas, to the flow path 250 according to part (B), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrocarbon gas, in particular methane. The burning unit 120 has the semi-cylindrical burning area 420 and fur- ther comprises the frame 125 provided for mounting of the burning unit 120 to the air-gas mixing unit 110. The air-gas mixing unit 110 forms the air-gas mixture supply channel 118 and is provided with the eccentric extension space 610 that forms a part of the adjustment mechanism 220. A boundary of the eccentric ex- tension space 610 is formed by the flow diverter 230. In contrast to Fig. 4, the flow diverter 230 may now interact with a movable flap 500 that is provided instead of the slidable flap 400, as described hereinafter. The movable flap 500 is a rotatable flap that is, by way of example, rotatably ar- ranged in the gas-tight pathway 210. According to part (A), the rotatable flap 500 is e.g. mounted to an operating ele- ment 510. The operating element 510 is illustratively a rotatable lever which is mounted rotatably to the air-gas mixing unit 110. lllustratively, the rotatable flap 500 is in a position associated with the flow path 240. Rotation of the rotatable lever 510 in a direction illustrated by an arrow 530 rotates the rotatable flap 500 in the same direction. According to part (B), the rotatable flap 500 is moved in the direction illustrated by the arrow 530 into a position associated with the flow path 250. In this posi- tion, the rotatable flap 500 closes the flow path 240 of part (A) and interacts with the flow diverter 230 to form the flow path 250. Rotation of the rotatable flap 500 in a direction opposed to the direction illustrated by the arrow 530 via a suitable rotation of the rotatable lever 510 enables re-opening of the flow path 240 of part (A). Fig. 6 shows in part (A) and part (B) the burner assembly 100 of Fig. 4 with the air-gas mixing unit 110 that is provided for mixing of air and gas to form the air- gas mixture 115, and the burning unit 120 for combustion of the air-gas mixture 115. The air-gas mixing unit 110 comprises the Venturi-type mixing nozzle 112. The air-gas mixing unit 110 is connected via the gas-tight seal 450 to the burning unit 120 to form the gas-tight pathway 210 that is adjustable from the flow path 240 according to part (A), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrogen gas, to the flow path 250 accord- ing to part (B), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrocarbon gas, in particular methane. The burning unit 120 has the semi-cylindrical burning area 420 and further comprises the frame 125 provided for mounting of the burning unit 120 to the air-gas mixing unit 110. The air-gas mixing unit 110 forms the air-gas mixture supply channel 118 and is provided with the eccentric extension space 610 that forms a part of the adjustment mechanism 220. In contrast to Fig. 4, instead of using the slidable flap 400, adjustment of the gas- tight pathway 210 from the flow path 240 according to part (A) to the flow path 250 according to part (B) is now obtained by replacing the burning unit 120 ac- cording to part (A) with the burning unit 120 according to part (B). More specifi- cally, in part (B) the burning unit 120 is provided with the flow diverter 230 of the adjustment mechanism 220. lllustratively, the flow diverter 230 is attached to, or integrally formed with, the burning unit 120 according to part (B) and extends into the eccentric extension space 610 to create the flow path 250. Fig. 7 shows in part (A) and part (B) the burner assembly 100 of Fig. 6 with the air-gas mixing unit 110 that is provided for mixing of air and gas to form the air- gas mixture 115, and the burning unit 120 for combustion of the air-gas mixture 115. The air-gas mixing unit 110 comprises the Venturi-type mixing nozzle 112. The air-gas mixing unit 110 is connected via the gas-tight seal 450 to the burning unit 120 to form the gas-tight pathway 210 that is adjustable from the flow path 240 according to part (A), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrogen gas, to the flow path 250 accord- ing to part (B), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrocarbon gas, in particular methane. The burning unit 120 has the semi-cylindrical burning area 420 and further comprises the frame 125 provided for mounting of the burning unit 120 to the air-gas mixing unit 110. The air-gas mixing unit 110 forms the air-gas mixture supply channel 118 and is provided with the eccentric extension space 610 that forms a part of the adjustment mechanism 220. In contrast to Fig. 6, the burning unit 120 according to part (A) comprises a bulge 710 that extends into the eccentric extension space 610. Preferably, the bulge 710 fills the extension space 610 at least approximately and, thus, forms the flow path 240. The bulge 710 may be attached to, or integrally formed with, the burn- ing unit 120 of part (A). Similar to Fig. 6, the flow path 250 according to part (B) is obtained by replacing the burning unit 120 according to part (A) with the burning unit 120 according to part (B). More specifically, in part (B) the burning unit 120 is provided with the flow diverter 230 of the adjustment mechanism 220. lllustratively, the flow diverter 230 is attached to, or integrally formed with, the burning unit 120 according to part (B). However, instead of extending into the eccentric extension space 610 to create the flow path 250, the flow diverter 230 in part (B) now merely closes the flow path 240 according to part (A) by means of a bulge 810 that may be at- tached to, or integrally formed with, the burning unit 120 of part (B). Furthermore, the semi-cylindrical burning area 420 of the burning unit 120 in part (B) is illustratively eccentrically positioned below the eccentric extension space 610. This is in contrast to part (A), where the semi-cylindrical burning area 420 is positioned at least approximately centrally below the air-gas mixture supply chan- nel 118, similar to a respective positioning in the previous figures. Fig. 8 shows in part (A) and part (B) the burner assembly 100 of Fig. 6 with the air-gas mixing unit 110 that is provided for mixing of air and gas to form the air- gas mixture 115, and the burning unit 120 for combustion of the air-gas mixture 115. The air-gas mixing unit 110 comprises the Venturi-type mixing nozzle 112. The air-gas mixing unit 110 is connected via the gas-tight seal 450 to the burning unit 120 to form the gas-tight pathway 210 that is adjustable from the flow path 240 according to part (A), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrogen gas, to the flow path 250 accord- ing to part (B), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrocarbon gas, in particular methane. The burning unit 120 has the semi-cylindrical burning area 420 and further comprises the frame 125 provided for mounting of the burning unit 120 to the air-gas mixing unit 110. The air-gas mixing unit 110 forms the air-gas mixture supply channel 118 and is provided with the extension space 610 that forms a part of the adjustment mechanism 220. However, in contrast to Fig. 6 the extension space 610 is no more eccentrically arranged but, instead, e.g. at least essentially centrally ar- ranged below the air-gas mixture supply channel 118. Similar to Fig. 6, the flow path 250 according to part (B) is obtained by replacing the burning unit 120 according to part (A) with the burning unit 120 according to part (B). More specifically, in part (B) the burning unit 120 is provided with the flow diverter 230 of the adjustment mechanism 220. lllustratively, the flow diverter 230 is attached to, or integrally formed with, the burning unit 120 according to part (B). By way of example, the flow diverter 230 forms a boundary of the exten- sion space 610 such that at least two lateral slots 810, 820 are formed as part of the flow path 250. Fig. 9 shows the burner assembly 100 of Fig. 6, part (A), with the air-gas mixing unit 110 that is provided for mixing of air and gas to form the air-gas mixture 115, and the burning unit 120 for combustion of the air-gas mixture 115. The air-gas mixing unit 110 comprises the Venturi-type mixing nozzle 112 and forms the air- gas mixture supply channel 118. The air-gas mixing unit 110 is connected to the burning unit 120 to form the gas-tight pathway 210 that is adjustable from the flow path 240, wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrogen gas, to the flow path 250 as illustrated in Fig. 10, part (A) to part (C), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrocarbon gas, in particular methane. However, in contrast to Fig. 6, part (A), the burning unit 120 now comprises a cy- lindrical burning area 910 instead of the semi-cylindrical burning area 420. Fur- thermore, the air-gas mixing unit 110 is simplified and shown without the exten- sion space 610 and illustration of the gas-tight seal 450 is omitted, for simplicity and clarity of the drawing. Fig. 10, part (A) to part (C) shows the burner assembly 100 of Fig. 9 with the air- gas mixing unit 110 that is provided for mixing of air and gas to form the air-gas mixture 115, and the burning unit 120 for combustion of the air-gas mixture 115. The air-gas mixing unit 110 comprises the Venturi-type mixing nozzle 112 and forms the air-gas mixture supply channel 118. The air-gas mixing unit 110 is con- nected to the burning unit 120 to form the gas-tight pathway 210 that is adjusta- ble from the flow path 240 according to Fig. 9, wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrogen gas, to flow path 250 as illustrated in part (A) to part (C), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrocarbon gas, in partic- ular methane. The burning unit 120 comprises the cylindrical burning area 910. In part (A), adjustment of the gas-tight pathway 210 from the flow path 240 ac- cording to Fig. 9 to the flow path 250 is illustratively obtained by replacing the burning unit 120 according to Fig. 9 with the burning unit 120 according to part (A). More specifically, in part (A) the burning unit 120 is provided with the flow di- verter 230 of the adjustment mechanism 220. lllustratively, the flow diverter 230 is attached to, or integrally formed with, the burning unit 120 according to part (A) and comprises at least one and, by way of example, two ring-shaped diverting webs 232, 234 which create a meander-shaped path that forms the flow path 250 in the burning unit 120. In part (B), adjustment of the gas-tight pathway 210 from the flow path 240 ac- cording to Fig. 9 to the flow path 250 is illustratively obtained by replacing the air- gas mixing unit 110 according to Fig. 9 with the air-gas mixing unit 110 according to part (B). More specifically, in part (B) the air-gas mixing unit 110 is provided with the flow diverter 230 of the adjustment mechanism 220. lllustratively, the flow diverter 230 is attached to, or integrally formed with, the air-gas mixing unit 120 according to part (B) and comprises at least one and, by way of example, one ring-shaped diverting web 236 which creates the flow path 250 in the burning unit 120. In part (C), adjustment of the gas-tight pathway 210 from the flow path 240 ac- cording to Fig. 9 to the flow path 250 is illustratively obtained by installing a di- verting inlay 1000 in the burning unit 120 according to Fig. 9. More specifically, in part (C) the diverting inlay 1000 forms the flow diverter 230 of the adjustment mechanism 220. lllustratively, the diverting inlay 1000 comprises at least one and, by way of example, two ring-shaped diverting webs 1032, 1034 which create a meander-shaped path that forms the flow path 250 in the burning unit 120. Fig. 11 shows in part (A) and part (B) the burner assembly 100 of Fig. 6 with the air-gas mixing unit 110 that is provided for mixing of air and gas to form the air- gas mixture 115, and the burning unit 120 for combustion of the air-gas mixture 115. The air-gas mixing unit 110 comprises the Venturi-type mixing nozzle 112. The air-gas mixing unit 110 is connected to the burning unit 120 to form the gas- tight pathway 210 that is adjustable from the flow path 240 according to part (A), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrogen gas, to the flow path 250 according to part (B), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hy- drocarbon gas, in particular methane. The burning unit 120 has the semi-cylindri- cal burning area 420 and further comprises the frame 125 provided for mounting of the burning unit 120 to the air-gas mixing unit 110. The air-gas mixing unit 110 forms the air-gas mixture supply channel 118 and is provided with the eccentric extension space 610 that forms a part of the adjustment mechanism 220. How- ever, illustration of the gas-tight seal 450 of Fig. 6 is omitted, for simplicity and clarity of the drawing. In contrast to Fig. 6, the flow path 250 according to part (B) is now obtained by mounting the flow diverter 230 of the adjustment mechanism 220 to the air-gas mixing unit 110. More specifically, the flow diverter 230 is illustratively formed as a separate plate-shaped element with a diverting portion 1100. The diverting por- tion 1100 protrudes in part (B) into the eccentric extension space 610 to form the flow path 250. Fig. 12 shows in part (A) and part (B) the burner assembly 100 of Fig. 11 with the air-gas mixing unit 110 that is provided for mixing of air and gas to form the air- gas mixture 115, and the burning unit 120 for combustion of the air-gas mixture 115. The air-gas mixing unit 110 comprises the Venturi-type mixing nozzle 112. The air-gas mixing unit 110 is connected to the burning unit 120 to form the gas- tight pathway 210 that is adjustable from the flow path 240 according to part (A), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hydrogen gas, to the flow path 250 according to part (B), wherein the burner assembly 100 is e.g. adapted for use with a type of gas that comprises hy- drocarbon gas, in particular methane. The burning unit 120 has the semi-cylindri- cal burning area 420 and further comprises the frame 125 provided for mounting of the burning unit 120 to the air-gas mixing unit 110. The air-gas mixing unit 110 forms the air-gas mixture supply channel 118 and is provided with the eccentric extension space 610 that forms a part of the adjustment mechanism 220. In contrast to Fig. 11, however, the flow path 250 according to part (B) is now ob- tained by mounting the flow diverter 230 of the adjustment mechanism 220 to the burning unit 120. Nevertheless, similar to Fig. 11 the flow diverter 230 is formed as a separate plate-shaped element with the diverting portion 1100 which pro- trudes in part (B) into the eccentric extension space 610 to form the flow path 250.

Claims

Claims 1. A burner assembly (100) comprising an air-gas mixing unit (110) for mixing of air and gas to form an air-gas mixture (115), and a burning unit (120) for combustion of the air-gas mixture (115), wherein the air-gas mixing unit (110) and the burning unit (120) are interconnected to form a gas-tight path- way (210) that is adapted for guiding the air-gas mixture (115) from the air- gas mixing unit (110) to the burning unit (120), and wherein the gas-tight pathway (210) is adjustable from a first flow path length (212) adapted for use with a first type of gas to a second flow path length (214) adapted for use with a second type of gas.

2. The burner assembly (100) of claim 1, wherein the second flow path length (214) is at least 25% greater than the first flow path length (212).

3. The burner assembly (100) of claim 1 or 2, further comprising an adjustment mechanism (220) that is configured for adjusting the gas-tight pathway (210) from the first flow path length (212) to the second flow path length (214). 4, The burner assembly (100) of claim 3, wherein the adjustment mechanism (220) comprises at least one flow diverter (230) that is arranged in the gas- tight pathway (210) for diverting the air-gas mixture (115) from a first flow path (240) having the first flow path length (212) toward a second flow path (250) having the second flow path length (214).

5. The burner assembly (100) of claim 4, wherein the at least one flow diverter (230) is movable in the gas-tight pathway (210) between a first position asso- ciated with the first flow path (240) and a second position associated with the second flow path (250).

6. The burner assembly (100) of claim 5, wherein the at least one flow diverter (230) is slidably or rotatably arranged in the gas-tight pathway (210).

7. The burner assembly (100) of any one of claims 4 to 6, wherein the adjust- ment mechanism (220) comprises a movable flap (400; 500) that is movable in the gas-tight pathway (210) between a first position associated with the first flow path (240) and a second position associated with the second flow path (250), and wherein the movable flap (400; 500) is adapted for interact- ing with the at least one flow diverter (230) for adjusting the gas-tight path- way (210) from the first flow path length (212) to the second flow path length (214).

8. The burner assembly (100) of claim 7, wherein the movable flap (400; 500) is slidably or rotatably arranged in the gas-tight pathway (210).

9. The burner assembly (100) of claim 7 or 8, wherein the movable flap (400; 500) is movably mounted to the air-gas mixing unit (110).

10. The burner assembly (100) of any one of claims 5 to 9, further comprising an operating element (410; 510) that is operable for moving the at least one flow diverter (230) or the movable flap (400; 500) between the first and second positions.

11. The burner assembly (100) of any one of claims 4 to 10, wherein the at least one flow diverter (230) is attached to, or integrally formed with, the air-gas mixing unit (110).

12. The burner assembly (100) of any one of claims 4 to 10, wherein the at least one flow diverter (230) is attached to, or integrally formed with, the burning unit (120).

13. The burner assembly (100) of any one of the preceding claims, wherein the first type of gas comprises hydrogen gas, wherein the second type of gas comprises hydrocarbon gas, in particular methane.

14. The burner assembly (100) of any one of the preceding claims, wherein the burning unit (120) forms a semi-cylindrical burning area (420) or a cylindrical burning area (910).

15. An air-gas mixture burning appliance comprising a burner assembly (100) ac- cording to any one of the preceding claims.