Flame and explosion-proof surface combustion gas burners

Abstract

The present invention relates to a flame- and explosion-proof surface-fired gas burner (1), which is notable in that it comprises a burner body (2) perforated by a set of holes (21), each of which is extended by a periphery (22) and which is arranged in several rows (24) of aligned holes (21), and a gas distributor (5) comprising a distributor body (50) provided with a number of longitudinal gas distribution branches (52), each branch (52) being perforated by a set of holes (58) bordered by a periphery (59). Furthermore, the distributor body (50) is positioned within the internal cavity (20) of the burner body (2) such that each hole in the distributor body (50) is coaxial with one hole (21) in the burner body (2), such that when the burner body (2) is coupled to an air supply and the distributor body (50) is coupled to a gas supply, air and gas mix only at the periphery (22) of the burner body (2).

Description

[Technical field]

[0001] The present invention relates to a surface-fired gas burner, in particular a hydrogen burner, which is intended in particular for use in domestic or industrial heating systems to heat a fluid circulating in a heat exchanger. [Background technology]

[0002] There have been two main successive generations of gas burners: the atmospheric burner and the fan burner.

[0003] In atmospheric burners, pressurized gas is discharged through a nozzle, which induces an air current through a converging-diverging device. Such burners have the disadvantage of releasing polluting emissions into the atmosphere.

[0004] Among fan burners, air / gas premix burners or "premix" burners allow total control of the premixing of gas and air (see, for example, the burner described in WO2014006103), thus significantly reducing polluting emissions.

[0005] However, in the case of premixed burners, the combustion occurs at the outer surface of the burner. To avoid rapid aging of the burner by exposing the burner jacket to glowing (as would be the case if the flame were too close to the jacket surface), the power variation range of such premixed burners is on the order of 1 to 3, or even up to 1 to 10, even if the jacket is made of a material that can withstand high temperatures or includes a specially developed design such as the burner described in US Pat. No. 5,399,633.

[0006] Furthermore, during operation of this air / gas premixed burner, the flow rate of the air-gas mixture must be varied to avoid extinguishing the flame through excessive flow, and conversely to avoid causing the flame to return into the burner through lack of sufficient flow, thus causing flashback.

[0007] Such flashback may in particular lead to deflagration or even detonation.

[0008] For a given burner, the adjustment range of its output is therefore limited by its maximum flow rate (corresponding to a gas discharge rate slower than the flame extinction) and by its minimum flow rate (corresponding to a gas discharge rate faster than the flashback rate).

[0009] In addition, these two limiting values ​​for the velocity of the air-gas mixture are related to the flame propagation speed in the gas under consideration, i.e. the type of gas. Thus, one and the same air-gas premixed burner will show different operating ranges depending on the type of gas used and its propagation speed.

[0010] By way of example, natural gas has an average propagation velocity of 0.37 meters / second, while hydrogen has an average propagation velocity of the order of 2.6 meters / second (ie, approximately seven times faster).

[0011] Prior art surface combustion burners are therefore also poorly suited for use with hydrogen gas when it is desired to be able to use such burners over a wide power output range.

[0012] However, in order to meet environmental and ecological standards, hydrogen could be a useful alternative fuel to power these burners. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] International Publication No. 2014 / 006103 Brochure Summary of the Invention

[0014] One object of the present invention is therefore to provide a surface-fired burner which, whilst being capable of operating in particular on hydrogen, is also usable over a wide power range and is reliable, i.e. avoiding flashback phenomena and the associated risks.

[0015] To this end, the present invention relates to a flame and detonation proof surface-fired gas burner.

[0016] According to the invention, the burner comprises a burner body made of metal or refractory material, the burner body defining an internal cavity connectable to an air supply and having an outer surface and an inner surface, the burner body being pierced by a set of holes, each hole being extended by a periphery projecting from the outer surface and having a central axis perpendicular to the outer surface, the holes being arranged in several rows of aligned holes, the gas distributor comprising a distributor body defining a housing connectable to a gas supply, the distributor body comprising a housing defining an internal cavity connectable to an air supply and having an outer surface and an inner surface, the burner body being pierced by a set of holes, each hole being extended by a periphery projecting from the outer surface and having a central axis perpendicular to the outer surface, the holes being arranged in several rows of aligned holes, the gas distributor comprising a distributor body defining a housing connectable to a gas supply, the distributor body comprising a housing defining an internal cavity connectable to a gas supply, the gas distributor body comprising a gas distributor defining a housing ... The body comprises a plurality of longitudinal gas distribution branches, each branch having two longitudinal walls spaced apart to define a longitudinal laminar gas distribution space therebetween, the gas distribution space opening into the housing at an inner longitudinal end thereof, the two walls of each branch meeting to form an outer longitudinal edge of the branch, a closed front end and a closed rear end, each branch being perforated by a set of holes aligned along its outer longitudinal edge, each hole being bordered by a peripheral edge that projects beyond an outer surface of the longitudinal edge, each peripheral edge being aligned with the longitudinal edge, the distributor body is arranged in the internal cavity of the burner body such that each of the holes of the distributor body is coaxial with a hole of the burner body, the distributor body and the burner body are arranged such that an air gap exists between the apex of the outer longitudinal edge of each of the branches and the inner surface of the burner body, and the apex of the periphery of each hole is greater than the outer diameter D1 of the apex of the periphery of the hole of the distributor body that faces the same hole, and The dimensions are determined so as to be immediately adjacent to the inlet, so that when the burner body is connected to an air supply and the distributor body is connected to a gas supply, air enters the burner body, flows between the branches and in the gaps of the distributor body, and exits the burner through the periphery of the burner body, while gas enters the housing of the distributor body, flows through the laminar spaces of the branches, then through the holes and periphery of the distributor body, and finally through the periphery of the burner body, where it meets and mixes with the air.

[0017] Thanks to these features of the invention, the gas and air flow through separate circuits in the burner with very little load loss and are mixed only at the last moment inside the edges of the burner body. These edges thus constitute microchambers for mixing the gas and the air, and the combustion takes place at the surface, i.e. on leaving these edges, thus preventing any flashback.

[0018] Such burners are therefore particularly suitable for use with hydrogen (a gas with a high flame propagation speed) since flashback and therefore any risk of detonation or deflagration are prevented.

[0019] It is also possible to control the mixed volume of gas and air to obtain a wide adjustment range.

[0020] Other advantages and non-limiting features of the present invention (singly or in combination):

[0021] At least one peripheral edge of the hole in the burner body and / or at least one peripheral edge of the hole in the distributor body is toothed with a notch.

[0022] - the burner body is formed from a cylindrical shell, closed at its rear end by a rear wall and provided at its front end with a front wall flange connectable to an air supply, the burner body holes are formed in said shell such that a row of holes extends axially on said shell, the distributor body comprises a hollow cylinder defining said housing of said body, said housing being centrally located and cylindrical, the longitudinal gas distribution branches extending radially around said cylinder, the distributor body being closed at its rear end by the rear wall and provided at its front end by a front flange a front flange having a central bore connectable to a gas supply source, the gas distributor comprising a gas pre-distribution device having a cylindrical body with an axially cylindrical central opening and several stages of radial passages, each of the radial passages extending from the central opening all the way to the outer surface of the cylindrical body, the gas pre-distribution device being axially disposed within the cylindrical housing of the distributor body such that its central opening faces the central bore of the flange and each of its radial passages opens into a laminar space in one branch of the distributor body.

[0023] - the cylindrical body of the gas pre-distribution device comprises several rear washers and one front washer, each of the rear and front washers having a cylindrical central opening and two opposing flat surfaces, the central openings being of the same diameter, the front and rear washers being assembled in abutment with each other such that their respective central openings are coaxial, and the rear washers have a set of radial grooves on one of their flat surfaces which, together with the opposite surface of the adjacent rear washer, define the radial passage.

[0024] The gas pre-distribution device includes a means for moving gas flowing into the gas pre-distribution device, the means for moving the gas so as to impart a helical motion to the gas as it flows through the interior of the central opening of the cylindrical body.

[0025] - The device for moving the gas is a fixed propeller.

[0026] - the shell of the burner body has a rear end, the rear wall of the burner body comprises a solid disc with an annular outer periphery that is hermetically welded to the rear end of the shell, the solid disc having a front face and at least one locating pin protruding from said front face, the at least one locating pin being inserted between two adjacent branches of the body of the gas distributor.

[0027] The distributor body is formed from a metal sheet that is folded back to form the gas distribution branches.

[0028] - The front and rear ends of each branch of the distributor body are closed by constriction machining and welding.

[0029] - The air gap has a height of at least 0.2 mm.

[0030] the ratio D2 / D1 of the inside diameter of a hole in the burner body to the outside diameter of the apex of a hole located opposite the same hole at its periphery is between 1.2 and 4;

[0031] - The gas is hydrogen.

[0032] Other characteristics, objects and advantages of the invention will become apparent from the following description, which is purely illustrative and non-limiting and which must be read with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0033] [Figure 1] 1 is an exploded perspective view of the elements constituting a possible embodiment of a gas burner according to the invention; [Diagram 2] FIG. 2 is a perspective view of the same burner with its various elements assembled together. [Diagram 3] FIG. 2 is a perspective view of a gas distributor in the gas burner of FIG. 1; [Figure 4] FIG. 4 is an exploded perspective view of the various elements that make up the gas distributor of FIG. 3; [Diagram 5] FIG. 3 is a longitudinal cross-sectional view of the gas burner taken along the line VV in FIG. 2. [Figure 6] 8 is a longitudinal cross-sectional view of the holes formed in the body and distributor of the burner taken along a cross section through line VI-VI in FIG. 7 . [Figure 7] FIG. 6 is an enlarged detailed view of the burner body and distributor shown in FIG. 5 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] In the remainder of this specification, the surface-fired gas burner 1 according to the invention will be described as operating with gas, preferably hydrogen, however, the burner 1 could also operate with another gas, for example natural gas, without departing from the scope of the invention.

[0035] In the remainder of this specification and in the claims, by convention, the term "front" refers to elements located or facing toward the end of the burner through which air is introduced into the burner (i.e., on the left side in Figures 1-5), and the term "rear" refers to elements located or facing in the opposite direction (i.e., on the right side in Figures 1-5).

[0036] Generally, the gas burner comprises a burner body 2 connectable to an air supply and a gas distributor 5 connectable to a gas supply.

[0037] According to a preferred (and therefore not exclusive) embodiment of the invention which will now be described in more detail, the burner body 2 and the gas distributor 5 are of generally cylindrical shape.

[0038] 1 it can be seen that the burner body 2 is interrupted at its rear end 26 by a rear wall 3 and is provided at its front end 25 with a front wall flange 4, and that the gas distributor 5 is interrupted at its rear end by a rear wall 6 and is provided at its front end with a front flange 7. These various elements will now be explained.

[0039] Burner body 2: The burner body 2 is formed by a hollow cylindrical shell 200 extending about a central longitudinal axis X-X' (which also constitutes the central longitudinal axis of the burner 1), said shell 200 preferably consisting of sheet metal.

[0040] The body 2 defines an internal cylindrical cavity 20 .

[0041] The shell is pierced by a number of holes 21, each of which extends outwardly as a periphery 22 (see in particular Figures 5 to 7). The periphery 22 surrounds the outer periphery of the hole 21. Each periphery 22 projects beyond the outer surface 23 of the body 2. Each hole 21 and its periphery 22 have a central axis Z1-Z'1 perpendicular to this outer surface 23 (see Figure 6). The inner surface of the shell is designated by the reference number 23'.

[0042] The rim 22 (more particularly its free end 220) is advantageously toothed with notches 22'. These notches 22' are used to create turbulence at the outlet of the body 2, thus enhancing the flame holding effect and preventing flame extinction.

[0043] The hole 21 and the rim 22 are "punched holes" obtained, for example, by stamping or punching a flat metal sheet, which is then bent to form the cylindrical body 2 and its edges are welded together.

[0044] The holes 21 are circular or nearly circular in shape and the periphery 22 is cylindrical or nearly cylindrical in shape.

[0045] Furthermore, the holes 21 (and therefore the peripheries 22) are aligned to form several axial rows 24 of holes, which run parallel to one another and to the central longitudinal axis X-X' of the body 2. Furthermore, the different rows 24 are preferably evenly distributed over the entire circumference of the burner body 2.

[0046] In a given row 24, the different holes 21 may be evenly spaced from one another, or may be grouped together to form an inverse pattern (eg, grouped in pairs as can be seen in each figure).

[0047] Back wall 3: The rear wall 3 consists of a solid disk 30 with an annular outer peripheral edge 31. The diameter of this rear wall 3 is adapted to the diameter of the burner body 2 (here the shell 200) so that its outer peripheral edge 31 can be welded to the rear end 26 of the body 2 (preferably to the inside of this body 2), as can be seen more clearly in the cross section of Figure 5. The rear wall 3 and the body 2 are thus welded in an airtight manner by a circular weld.

[0048] Furthermore, the rear wall 3 is provided with at least one positioning pin 32 (preferably three pins) which protrude from the front face 301 of the disc 30 towards the interior of the cavity 20 when this rear wall is assembled to the body 2. The function of these pins will be explained in detail below.

[0049] Front wall flange 4: As can be seen in figure 5, the front wall flange 4 is an annular element intended to be welded to the front end 25 of the burner body 2 in order to allow connection of this body 2 to an air supply (not shown) required for the combustion of the gases. The flange 4 comprises, for example, a ring 40 welded to the inside of this body 2, which ring 40 flares forward as a radial flange 41 for mounting the body 2.

[0050] Gas distributor 5: The gas distributor 5 has the function of distributing gas (particularly hydrogen) as close as possible to each hole 21 of the burner body 2, and also distributing the air circulating within the body 2, as will be explained in more detail subsequently.

[0051] The distributor 5 is intended to be inserted axially into the burner body 2 .

[0052] As can be seen more clearly in FIGS. 1 and 3 to 5 , the distributor 5 comprises a distributor body 50 , a rear wall 6 and a front flange 7 .

[0053] The body 50 comprises a hollow cylinder 51 with a central longitudinal axis X1-X'1, which is coaxial with the axis X-X' of the burner 1 when the distributor 5 is mounted in the body 2. The cylinder 51 is provided with a number of radial branches 52 arranged in a star shape around the circumference of the cylinder 51. The cylinder 51 defines a cylindrical central housing 53. Each branch 52 extends both radially outward relative to the central axis X1-X'1 and over the entire length of the cylinder 51.

[0054] As can be seen more clearly in Fig. 7, each branch 52 comprises two flat walls 54, 54' parallel or nearly parallel to each other. The walls 54, 54' are spaced apart to form a laminar space 55 between them. At its radially inner end, the laminar space 55 opens into the cylindrical central housing 53. At their radially outer end, the two walls 54, 54' are joined to each other by a joining area that defines a radially outer longitudinal edge 56 of each branch 52. This edge 56 is preferably curved inwards along its cross section with its concave surface facing towards the laminar space 55.

[0055] The body 50 consists of a strip of sheet metal, bent to form a cylinder 51 and folded back several times to form branches 52 which open into a housing 53 .

[0056] As can be seen in figure 3, each branch 52 is hermetically closed at its front end 57 and at its rear end 57', for example by narrowing the two walls 54, 54' together and then welding the edges of these walls together.

[0057] Finally, the radially outer longitudinal edge 56 of each branch 52 is pierced by a number of holes 58, each of which is extended by a peripheral edge 59 (see Figures 6 and 7), which surrounds the outer periphery of the hole 58. Each peripheral edge 59 projects outwardly from a radially outer surface 560 of edge 56. Each hole 58 and its peripheral edge 59 have a central axis Z2-Z2' perpendicular to outer surface 560.

[0058] The rim 59 is advantageously toothed with notches 59', which makes it possible to create turbulence on leaving the rim 59 and thus improve the air / gas mixture entering the holes 21 and then the rim 22.

[0059] The holes 58 and the periphery 59 are "punched holes" obtained, for example, by stamping a metal plate. The holes 58 are circular or nearly circular, and the periphery 59 is cylindrical or nearly cylindrical.

[0060] The distributor body 50 has at most as many branches 52 as there are rows 24 of holes 21 in the burner body 2. It is possible that there are fewer branches 52 than there are rows 24 of holes, in which case only air will exit the rows 24 of holes. It is preferred that there are as many branches 52 as there are rows 24 of holes.

[0061] The holes 58 (and thus the periphery 59) are axially aligned along the longitudinal edge 56. Furthermore, on each longitudinal edge 56 of each branch 52 there are as many holes 58 as there are holes 21 in one row 24 of the burner body 2. On a given longitudinal edge 56, the different holes 58 can be evenly spaced from one another or conversely grouped into groups of several holes to form a pattern (e.g., grouped in pairs as can be seen in the figures).

[0062] The rear wall 6 is a disk with an outside diameter equal to the inside diameter of the cylindrical central housing 53. The rear wall 6 is welded to the cylinder 51 in an airtight manner to seal off the housing 53.

[0063] The front flange 7 allows the connection of the distributor body 50 to a source of pressurized gas (hydrogen) (not shown).

[0064] The front flange 7 preferably comprises a disk 70 pierced by a central hole 71. The outside diameter of the disk 70 is equal to the inside diameter of the cylindrical central housing 53. As can be seen in Figure 3, this disk 70 is welded in a gas-tight manner at its outer periphery to the front end of the cylinder 51. This disk 70 extends forward as a tube 72 of longitudinal axis X-X', thereby allowing the connection of the front flange 7 to a gas supply (not shown).

[0065] assembly The distributor 5 is inserted axially inside the cylindrical cavity 20 of the burner body 2 (to which the rear wall 3 has previously been welded) and then the front wall flange 4 itself is welded to the burner body 2 .

[0066] It can be seen that in this assembled state, the positioning pins 32 are each positioned between two adjacent branches 52, thus preventing any rotation of the distributor 5 relative to the burner body 2 about its axis X-X'.

[0067] The distributor 5 and body 2 are also assembled such that each hole 58 (and therefore its periphery 59) is coaxial with one hole 21 and its periphery 22 of the burner body 2 (see the alignment of axes Z1-Z'1 and Z2-Z'2 in Figure 6).

[0068] size: As can be seen in FIG. 6, the outer diameter D1 of the apex 590 at each periphery 59 of the distributor 50 is smaller than the inner diameter D2 of the hole 21 in the burner body 2 opposite which the apex 590 lies.

[0069] Furthermore, the height H1 between the apex 590 of each rim 59 (i.e. its radially outermost end) and the inner surface 23' of the shell 2 is as small as possible so that the apex 590 is in the immediate vicinity of the inlet 210 of the hole 21. The rim 59 thus constitutes in effect a gas micro-injector opening into the hole 21, and air / gas mixing takes place within the rim 22. The height H1 corresponds to the clearance of the axial insertion of the body 50 of the distributor 5 within the body 2 (if these two elements are cylindrical). H1 is preferably less than or equal to 0.1 mm.

[0070] The distributor body 50 and the burner body 2 are dimensioned so that between the top end 561 of the longitudinal edge 56 of each branch 52 and the inner surface 23' of the shell 2 there is a gap 27 for the passage of air.

[0071] The height H2 between the apex 561 of the edge 56 of each branch 52 and the inner surface 23' of the shell is preferably 0.2 mm or greater.

[0072] The height H3 between the top of the free end 220 of the rim 22 of the burner body 2 and the inner surface 23' of said body 2 is preferably between 0.8 and 2 mm.

[0073] According to alternative embodiments, not shown, the burner body 2 and the gas distributor 5 could have shapes other than cylindrical.

[0074] The burner body 2 may, for example, have holes 21 with the aforementioned rims 22 drilled only in a portion of its surface that serves as a combustion surface. Such a combustion surface may, for example, be flat, slightly curved or V-shaped.

[0075] In this case, the shape of the distributor body 50 is accordingly adapted to be able to be inserted into the cavity 20 of the body 2. The body 50 still comprises (as described above) branches 52 perforated by holes 58 provided with a periphery 59, but these branches 52 are not radial.

[0076] Finally, the features previously discussed regarding the relative positioning and dimensions of holes 21, 58 will be the same.

[0077] In the special case where the burner body 2 and the gas distributor 5 are cylindrical, it is preferred that the gas burner 1 further comprises a gas pre-distribution device 8 and further comprises a device 9 for moving the gas flowing into said device 8.

[0078] Gas pre-distribution device 8: In the embodiment shown (particularly in Figures 1 and 4), the gas pre-distribution device 8 comprises a pair of annular washers 80 assembled in abutting relation to one another, as well as one front washer 81 (see Figures 1 and 4).

[0079] Each annular washer 80 has a cylindrical central opening 800 , a flat front surface 801 , an opposing flat rear surface 802 , and cylindrical side surfaces 803 .

[0080] Each annular washer 80 (e.g., here on the front face 801) is provided with a set of straight grooves 804 that are cut through the thickness of the washer and extend radially from the central opening 800 until they open onto face 803. There are as many grooves 804 on each washer 80 as there are branches 52 on the distributor 5.

[0081] When different washers 80 are pressed tightly against each other, the rear face 802 of one washer comes into contact with the front face 801 of the adjacent washer, which rear face 802 forms respective passages 805 with different grooves 804 (see Figures 1, 5 and 7). These passages 805 have mouths 806 opening onto the side surfaces 803. Several successive stages 807 of radial passages 805 are thus obtained.

[0082] The front washer 81 has a cylindrical central opening 810, a flat front surface 811, and an opposite flat rear surface 812.

[0083] Apertures 800, 810 are coaxial and of the same diameter.

[0084] 4, a central opening 810 has an annular step 814 formed on its inside, so that the opening 810 has a rear portion 815 of the same inner diameter as the diameter of the opening 800, and a front portion 816 of a larger inner diameter than the rear portion 815, such that at the front portion 816 a housing 817 is formed for receiving a device 9, which is preferably a propeller.

[0085] Thus, the annular step 814 makes it possible to prevent the propeller 9 from moving axially rearward.

[0086] When the front washer 81 is pressed snugly against the immediately adjacent washer 80, the rear face 812 contacts the front face 801 of that washer, also defining radial passages 805 in the grooves 804. It would also be possible to have grooves 804 on the rear face 802.

[0087] The different washers 80 and the front washer 81 are assembled against one another and the gas pre-distribution device 8 thus formed is inserted axially into the housing 53 of the distributor 5 so that the rear face 802 of the last washer 80 is in contact with the rear wall 6 and the front face 811 of the front washer 81 is in contact with the disk 70. For this purpose, the outside diameters of the different washers 80, 81 are equal to the inside diameter of the cylinder 51 (within the range of the insertion gap).

[0088] In this assembled state (more clearly seen in FIG. 5), it can be seen that the disk 70 interacts with the housing 817 to prevent the fixed propeller 9 from moving axially forward, thus holding it between the forward flange 7 and the washer 81.

[0089] The different washers 80, 81 are angularly aligned with respect to the longitudinal axis X-X' so that their respective grooves 804 overlap and the outer mouths 806 of the passages 805 are in axial alignment 82, as can be seen in Fig. 1. For this purpose, the different washers 80, 81 can be provided with foolproofing measures to ensure a correct assembly. One alignment 82 is shown diagrammatically in Fig. 1 by dashed lines.

[0090] Furthermore, the washers 80, 81 are inserted into the housing 53 such that the outer mouths 806 of the radial passages 805 open directly into one of the laminar spaces 55. In other words, each of the alignments 82 faces one of the branches 52.

[0091] According to a simplified variant embodiment (not shown), the gas pre-distribution device 8 can also be formed not from different washers 80, 81, but instead from a single solid cylindrical body. Such a solid cylindrical body has an axial cylindrical central opening corresponding to the set of central openings 800, 810 and a number of radial passages 805 opening firstly into this central opening and secondly onto the outer surface 803 of the cylindrical body similar to the mouths 806. These different passages 805 are distributed over different stages 807, making it possible to supply gas to each branch 52 of the distributor body. Finally, such a single cylindrical body also has a housing 817 for receiving a propeller 9 at the front end of its central opening.

[0092] It should be noted that it is not necessary to have as many passage stages 807 as there are holes 58 (or edges 59) on a given branch 52. Thus, as a purely illustrative example, in the exemplary embodiment shown in the drawings, there are seven radial passage stages 807 for fourteen edges 59 on each branch 52.

[0093] 4, the fixed propeller 9 comprises a central disk 91 from which extends a number of blades 92. Each blade 92 is oriented at a setting angle that allows it to be deflected to impart a helical motion to the incoming gases within the central openings 800, 810.

[0094] material: The burner body 2, the rear wall 3 and 6, the flanges 4 and 7, the gas distributor 5, the gas pre-distribution device 8 and the propeller 9 are advantageously made of metal, in particular stainless steel, although the device 8 could be made of aluminium or a composite material. The burner body 2 could also be made of a refractory material.

[0095] Operation: Pipe 72 is connected to a source of pressurized gas (preferably hydrogen), and forward flange 4 is connected to a source of air (also pressurized).

[0096] We will now describe the path of air inside the gas burner 1. This path is symbolized by arrows referenced with the subscript "a".

[0097] The air enters the annular space around the tube 72 (arrow a1 in FIG. 5) and then divides into layers of air within each space 520 formed between the branches 52 (arrow a2). The air is then directed radially outwardly along the walls 54-54' (arrow a3 in FIG. 7) and axially between the top end 561 of the edge 56 and the inner surface 23' of the shell (arrow a4 in FIG. 6). Finally, the air escapes through the rim 22 (arrow a5 in FIG. 6).

[0098] We will now describe the gas paths inside the gas burner 1. These paths are symbolized by arrows referenced with the subscript "g".

[0099] The gas enters the tube 72 (arrow g1 in FIG. 5) and is then forced into a spiral motion (arrow g2 in FIG. 5) by the fixed propeller 9. In the special case where the gas is hydrogen (thus an extremely volatile gas), this allows an ideal distribution of the hydrogen generally in all the passages 805.

[0100] Thus, the gas is forced to flow into the different passages 805 (arrow g3 in Figs. 5 and 7) and out of those passages 805 (arrow g4 in Figs. 5 and 7) into the laminar spaces 55. Because the gas is pre-distributed into the different passages 805, each laminar space 55 is uniformly supplied with gas over its entire axial length.

[0101] The gas then exits through the holes 58 and the rim 59 of the distributor 5 (arrow g5 in FIG. 6) and then enters the holes 21 and the rim 22 (arrow g6 in FIG. 6) where it is mixed with the air. Thus, when leaving these rims 22, air / gas mixing and combustion occurs only inside the rims 22. As a result, there is no risk of flashback in the spaces 520 or in the radial branches 52.

[0102] Thus, the gas burner according to the invention is able to operate with hydrogen, despite its extreme volatility, while providing a power regulation range of at least 1 to 10 without any risk of flashback and therefore without any risk of deflagration or detonation.

[0103] Finally, the measurements carried out make it possible to demonstrate that combustion with hydrogen can be carried out at air lambda values ​​of 1.3 to 2 and NOx emission levels of 0.5 to 3 ppm.

[0104] In embodiments without predistribution device 8 , gas exiting tube 72 enters housing 53 directly.

Claims

1. In a detonation-proof and detonation-proof surface combustion gas burner (1), It comprises a burner body (2) made of metal or refractory material and a gas distributor (5); the burner body (2) defining an internal cavity (20) connectable to an air supply source and having an outer surface (23) and an inner surface (23'); the burner body (2) is perforated by a set of holes (21), each of which is extended by a rim (22) that projects from its outer surface (23) and whose central axis (Z1-Z'1) is perpendicular to said outer surface (23), the holes (21) being arranged in several rows (24) of aligned holes (21); the gas distributor (5) comprising a distributor body (50) defining a housing (53) connectable to a gas source; the distributor body (50) comprises a plurality of longitudinal gas distribution branches (52), each branch (52) comprising two longitudinal walls (54, 54') spaced apart to define a longitudinal laminar gas distribution space (55) therebetween, the gas distribution space (55) opening into the housing (53) at its inner longitudinal end, the two walls (54, 54') of each branch (52) meeting to form an outer longitudinal edge (56) of the branch (52), a closed front end (57) and a closed rear end (57'); each branch (52) is pierced by a set of holes (58) aligned along its outer longitudinal edge (56), each hole (58) being bordered by a peripheral edge (59) projecting beyond the outer surface (560) of said longitudinal edge (56), each peripheral edge (58) having a central axis (Z2-Z'2) perpendicular to this outer surface (560) of said longitudinal edge (56); The distributor body (50) is arranged in the internal cavity (20) of the burner body (2) such that each hole (58) of the distributor body (50) is coaxial with one hole (21) of the burner body (2); and The distributor body (50) and the burner body (2) are dimensioned so that the inner diameter D2 of a hole (21) in the burner body (2) is greater than the outer diameter D1 of the apex (590) of the rim (59) of the hole (58) of the distributor body (50) facing the same hole (21), so that there is a gap (27) for air passage between the apex (561) of the outer longitudinal edge (56) of each branch (52) and the inner surface (23') of the burner body (2), and so that the apex (590) of the rim (59) of each hole (58) is in the immediate vicinity of the inlet (210) of the hole (21) facing the apex (590), thereby allowing the burner body ( when the burner (1) (2) is connected to an air supply source and the distributor body (50) is connected to a gas supply source, air enters the burner body (2), flows between the branches (52) of the distributor body (50) and in the gaps (27), and leaves the burner (1) through the periphery (22) of the burner body (2), while gas enters the housing (53) of the distributor body (50), flows through the laminar spaces (55) of the branches (52), then through the holes (58) and periphery (59) of the distributor body (50), and finally through the periphery (22) of the burner body (2), where it meets and mixes with the air; A gas burner (1) characterized by:

2. 2. A gas burner (1) according to claim 1, characterized in that at least one peripheral edge (22) of the hole (21) in the burner body (2) and / or at least one peripheral edge (59) of the hole (58) in the distributor body (50) is toothed with notches (22', 59').

3. the burner body (2) is formed from a cylindrical shell (200) closed at its rear end (26) by a rear wall (3) and provided at its front end (25) with a front wall flange (4) connectable to said air supply source; the holes (21) of the burner body (2) are formed in the shell (200) such that the rows (24) of the holes (21) extend axially on the shell (200); the distributor body (50) comprises a hollow cylinder (51) defining the housing (53) of the body, the housing (53) being centrally located and cylindrical; the longitudinal gas distribution branches (52) extend radially around the cylinder (51); the distributor body (50) is closed at its rear end by a rear wall (6) and at its front end by a front flange (7), the front flange (7) being provided with a central hole (71) connectable to the gas source; The gas distributor (5) comprises a gas pre-distribution device (8) having a cylindrical body with an axially cylindrical central opening (800, 810) and several stages (807) of radial passages (805), each radial passage (805) extending from the central opening (800, 810) all the way to the outer surface (803) of the cylindrical body; and the gas pre-distributor (8) is arranged axially inside the cylindrical housing (53) of the distributor body (50) so that its central openings (800, 810) face the central hole (71) of the flange (7) and each of its radial passages (805) opens into the laminar space (55) in one branch (52) of the distributor body (50); 2. Gas burner (1) according to claim 1, characterized in that

4. The cylindrical body of the gas pre-distribution device (8) comprises several rear washers (80) and one front washer (81), each of which has a cylindrical central opening (800, 810) and two opposing flat surfaces (801, 802, 811, 812), and the central openings (800, 810) are of the same diameter. The front washer (81) and the rear washer (81) are of the same diameter.

4. A gas burner (1) according to claim 3, characterized in that the rear washers (80) and the rear washers (80) are assembled in abutment with each other so that their respective central openings (800, 810) are coaxial, and the rear washers (80) have a set of radial grooves (804) on one of their flat surfaces (801, 802) which, together with the opposite surface (801, 802) of the adjacent rear washers (80), define the radial passages (805).

5. 4. The gas burner (1) according to claim 3, characterized in that the gas pre-distribution device (8) comprises a device (9) for moving the gas flowing into the gas pre-distribution device (8), the device (9) for moving the gas so as to give a spiral motion to the gas as it flows inside the central opening (800, 810) of the cylindrical body.

6. 6. Gas burner (1) according to claim 5, characterized in that the device (9) for moving the gas is a fixed propeller.

7. the shell (200) of the burner body (2) has a rear end (26), and the rear wall (3) of the burner body (2) comprises a solid disk (30) with an annular outer periphery (31) that is hermetically welded to the rear end (26) of the shell (200); The solid disc (30) has a front surface (301) and is provided with at least one locating pin (32) protruding from the front surface (301); and the at least one positioning pin (32) is inserted between two adjacent branches (52) of the body (50) of the gas distributor (5); 4. Gas burner (1) according to claim 3, characterized in that

8. 2. A gas burner (1) according to claim 1, characterized in that the distributor body (50) is made from a metal plate folded over to form the gas distribution branches (52).

9. 9. The gas burner (1) according to claim 8, characterized in that the front end (57) and the rear end (57') of each branch (52) of the distributor body (50) are closed by constriction and welding.

10. 2. A gas burner (1) according to claim 1, characterized in that the gap (27) for the passage of air has a height (H2) of at least 0.2 mm.

11. 2. A gas burner (1) according to claim 1, characterized in that the ratio D2 / D1 of the inner diameter (D2) of a hole (21) in the burner body (2) to the outer diameter (D1) of the top end (590) at the periphery (59) of a hole (58) arranged facing this same hole (21) is between 1.2 and 4.

12. 2. Gas burner (1) according to claim 1, characterized in that the gas is hydrogen.

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