Flame-proof and explosion-proof surface combustion gas burner

Abstract

The present invention relates to a flame-proof and explosion-proof surface combustion gas burner (1). This burner is notable in that it comprises a burner body (2) pierced with a series of orifices (21), each of which is extended by a rim (22), these orifices (21) being arranged in several rows (24) of aligned orifices (21), and a gas distributor (5) which comprises a distributor body (50) equipped with a plurality of longitudinal gas-distribution branches (52), each branch (52) being pierced with a line of orifices which are bordered by a rim (59). Moreover, the distributor body (50) is placed inside the burner body (2) in such a way that each orifice of the distributor body (50) is coaxial with an orifice (21) of the burner body (2) so that when the burner body (2) is coupled to an air supply source and the distributor body (50) is coupled to a gas supply source, the air and the gas mix only at the rims (22) of the burner body (2).

Description

FIELD OF INVENTION

[0001] The present invention relates to a surface combustion gas burner, in particular a hydrogen burner. Such a burner is intended, in particular, for use in domestic or industrial heating appliances, to heat a fluid circulating in a heat exchanger. STATE OF THE ART

[0002] Two main generations of gas burners have succeeded one another, namely atmospheric burners and forced-air burners.

[0003] In atmospheric burners, pressurized gas is emitted through a nozzle and drives an airflow via a convergent / divergent device. Such a burner has the disadvantage of emitting pollutants into the atmosphere.

[0004] Among forced-air burners, air / gas premix burners, or "premix" burners, allow for precise control of the gas and air premix (see, for example, the burner described in document WO2014006103). Pollutant emissions are thus considerably reduced.

[0005] However, in the case of a premix burner, combustion takes place on the burner's outer surface. To prevent rapid aging of the burner due to reddening of its casing (which occurs if the flame gets too close to its surface), the power variation range of such a premix burner is on the order of 1 to 3, or even a maximum of 1 to 10 if the casing is made of a high-temperature resistant material or has a specifically designed feature, such as the burner described in document WO2014006103.

[0006] Furthermore, during the operation of this air / gas premix burner, the flow rate of the air and gas mixture must be varied in order to avoid the flame being lifted by an excess of flow rate and conversely to prevent the flame from returning to the burner by a lack of sufficient flow rate, thus causing a flashback.

[0007] Such a backfire can indeed lead to a deflagration, or even a detonation.

[0008] For a given burner, the modulation range of its power is therefore regulated by its maximum flow rate, which corresponds to a gas exit velocity lower than the flame lift-off velocity, and by its minimum flow rate, which corresponds to a gas exit velocity higher than the flame return velocity.

[0009] Furthermore, these two extreme limits of the air / gas mixture velocity are linked to the flame propagation speed of the gas in question—in other words, to its nature. Thus, the same air / gas premix burner will offer a different operating range depending on the type of gas used and its propagation speed.

[0010] As an indication, natural gas has an average propagation speed of 0.37 meters / second and hydrogen an average propagation speed of around 2.6 meters / second, which is almost seven times faster.

[0011] State-of-the-art surface combustion burners are therefore not well suited to the use of hydrogen gas, especially if one wishes to be able to use such a burner over a wide range of power variations.

[0012] However, in order to comply with environmental and ecological criteria, hydrogen could be an interesting alternative as a fuel to power these burners. DESCRIPTION OF THE INVENTION

[0013] One aim of the invention is therefore to propose a surface combustion burner which can operate in particular with hydrogen, while being reliable, i.e. avoiding the phenomenon of flashback and the associated risks and while being able to be used over a large range of power variations.

[0014] For this purpose, the invention relates to an explosion-proof and anti-detonating surface combustion gas burner.

[0015] According to the invention, this burner comprises a burner body made of metal or refractory material and a gas distributor. The burner body defines an internal cavity connectable to an air supply and has an outer face and an inner face. The burner body is pierced with a series of orifices, each of which extends into a rim projecting from this outer face and whose central axis is normal to this outer face. These orifices are arranged in several aligned rows. The gas distributor comprises a distributor body that defines a housing connectable to a gas supply. The distributor body comprises a plurality of longitudinal gas distribution branches. Each branch comprises two longitudinal walls, spaced apart to define a longitudinal lamellar gas distribution space between them.which opens at its internal longitudinal end into said housing, the two walls of each branch joining to form an external longitudinal edge, a closed front end and a closed rear end of said branch, each branch is pierced by a series of orifices aligned along its external longitudinal edge, each orifice being bordered by a rim that projects on the external face of said longitudinal edge and each orifice having a central axis normal to this external face of said longitudinal edge, the distributor body is disposed in the internal cavity of the burner body so that each orifice of the distributor body is coaxial with an orifice of the burner body, the distributor body and the burner body are dimensioned so that the internal diameter D2 of an orifice of the burner body is greater than the external diameter D1 of the top of the rim of an orifice of the distributor body disposed opposite this same orifice,such that there is an air gap between the top of the outer longitudinal edge of each branch and the inner face of the burner body, and such that the top of the rim of each orifice is in the immediate vicinity of the inlet of the orifice opposite which it is positioned, so that when the burner body is connected to an air supply and the distributor body to a gas supply, air enters the burner body, flows between the branches of the distributor body and through the gap, and escapes from the burner through the rims of the burner body, while the gas enters the housing of the distributor body, flows through the lamellar space of the branches and then through the orifices and rims of this distributor body, and finally through the rims of the burner body where it meets the air and is mixed with it.

[0016] Thanks to these features of the invention, the gas and air circulate within the burner, where pressure losses are extremely low, through separate circuits, and are only mixed at the last moment inside the rims of the burner body. These rims thus constitute micro-chambers for mixing the gas and air, and combustion takes place on the surface, i.e., at the exit of these rims, thereby preventing any flashback.

[0017] Such a burner is therefore particularly suitable for use with hydrogen, a gas which has a high flame propagation speed, since the flashback is prevented and therefore also any risk of detonation or deflagration.

[0018] Furthermore, the volumes of gas and air mixed are controlled, allowing for a wide modulation range.

[0019] According to other advantageous and non-limiting features of the invention, taken alone or in combination: At least one rim of an orifice in the burner body and / or at least one rim of an orifice in the distributor body is serrated to present notches. The burner body is formed of a cylindrical shell, closed at its rear end by a bottom and whose front end is fitted with a front flange connectable to the air supply. The orifices of the burner body are formed in said shell such that the rows of orifices extend axially along this shell. The distributor body comprises a hollow cylinder that delimits said housing of this body, this housing being central and cylindrical. The longitudinal branches of gas distribution extend radially around this cylinder. The distributor body is closed at its rear end by a bottom and at its front end by a front flange, fitted with a central hole connectable to the gas supply.The gas distributor includes a gas pre-distribution device, which comprises a cylindrical body having a central axial cylindrical opening and several stages of radial channels, each radial channel extending from said central opening to the outer surface of said cylindrical body. This gas pre-distribution device is arranged coaxially inside the cylindrical housing of the distributor body, such that its central opening is opposite the central hole of the flange and each of its radial channels opens into the lamellar space of a branch of the distributor body. The cylindrical body of the gas pre-distribution device comprises several rear washers and one front washer, each of these rear and front washers having a central cylindrical opening and two opposing flat faces, these central openings being of the same diameter.The front washer and the rear washers are assembled against each other so that their respective central openings are coaxial. The rear washers have, on one of their flat faces, a series of radial grooves which, together with the opposite face of an adjacent rear washer, define said radial channels. The gas pre-distribution device includes a device for setting the gas entering this gas pre-distribution device in motion, to impart a helical motion to this gas as it flows inside the central opening of the cylindrical body. The gas setting device is a fixed helix. The burner body shell has a rear end, in that the bottom of the burner body comprises a solid disc with a peripheral annular rim which is welded in a gas-tight manner to the rear end of the shell.in that said solid disc has a front face and is provided with at least one positioning finger projecting from this front face, and in that said at least one positioning finger is inserted between two adjacent branches of the gas distributor body. The distributor body is formed from a sheet of metal folded over itself to form the gas distribution branches. The front and rear ends of each branch of the distributor body are closed by pinching and welding. The air gap has a height greater than or equal to 0.2 mm. The ratio D2 / D1 between the inner diameter of an orifice in the burner body and the outer diameter of the top of the rim of an orifice arranged opposite that same orifice is between 1.2 and 4. The gas is hydrogen. DESCRIPTION OF THE FIGURES

[0020] Other features, purposes and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which: there figure 1 is an exploded perspective view of the elements constituting a possible embodiment of the gas burner according to the invention; the figure 2 is a perspective view of the same burner, whose various elements are in their assembled position; the figure 3 is a perspective view of the gas distributor of the gas burner of the figure 1 ; there figure 4 is an exploded perspective view of the various components of the gas distributor of the figure 3 ; there figure 5 is a longitudinal cross-sectional view of the gas burner, taken along the cutting plane passing through the VV line of the figure 2 ; there figure 6is a longitudinal cross-sectional view of the orifices provided in the burner body and in the distributor, taken along the cutting plane passing through line VI-VI of the figure 7 ; there figure 7 is an enlarged detail view of the burner body and distributor shown on the figure 5 . DETAILED DESCRIPTION OF THE INVENTION

[0021] In the following description, the surface combustion gas burner 1 according to the invention is described as operating with a gas that is preferably hydrogen. However, it could also operate with another gas, for example natural gas, without departing from the scope of the invention.

[0022] In the remainder of the description and claims, by convention, the term "front" refers to the elements that are located or oriented towards the end of the burner through which air is introduced into it (i.e., on the left side of the figures 1 to 5) and the term "rear" refers to elements that are located or oriented on the opposite side (i.e., to the right on the figures 1 to 5 ).

[0023] In general, the gas burner 1 includes a burner body 2 connectable to an air supply source and a gas distributor 5 connectable to a gas supply source.

[0024] According to a preferred (and therefore non-exclusive) embodiment of the invention, which will now be described in more detail, the burner body 2 and the gas distributor 5 are generally cylindrical in shape.

[0025] On the figure 1 We can see that the burner body 2 is closed at its rear end 26 by a bottom 3 and is fitted at its front end 25 with a front flange 4, and that the gas distributor 5 is closed at its rear end by a bottom 6 and is fitted at its front end with a front flange 7. These different elements will now be described. Burner body 2:

[0026] The burner body 2 is formed of a hollow cylindrical ferrule 200 extending around a central longitudinal axis X-X', which also constitutes the central longitudinal axis of the burner 1. This ferrule 200 is preferably made of a thin sheet metal.

[0027] This body 2 delimits an internal cylindrical cavity 20.

[0028] The said ferrule is pierced with a plurality of orifices 21, each of which extends outwards by a rim 22, (see in particular the figures 5 to 7 The rim 22 surrounds the periphery of the orifice 21. Each rim 22 projects onto the outer face 23 of the body 2. Each orifice 21 and its rim 22 have a central axis Z1-Z'1 which is normal to this outer face 23 (see figure 6 ). The inner face of the ferrule is referenced 23'.

[0029] The rim 22 (and more particularly its free end 220) can advantageously be serrated so as to present notches 22'. These notches 22' make it possible to create turbulence at the exit of the body 2 and thus to strengthen the gripping effect of the flame and to prevent its detachment.

[0030] The orifices 21 and the rims 22 are, for example, "burst holes", obtained by stamping or punching a flat metal sheet, which is then bent to form the cylindrical body 2 and whose two edges are welded.

[0031] These orifices 21 are circular or substantially circular and the rims 22 are cylindrical or substantially cylindrical.

[0032] Furthermore, the orifices 21 (and therefore the rims 22) are aligned to form several axial rows 24 of orifices. These rows 24 extend parallel to each other and also parallel to the central longitudinal axis XX' of the body 2. In addition, preferably, the various rows 24 are evenly distributed around the entire circumference of the burner body 2.

[0033] In a given row 24, the different orifices 21 can be regularly spaced from each other or, on the contrary, grouped together to form a pattern, for example grouped in pairs as can be seen in the figures. Background 3:

[0034] The base 3 consists of a solid disc 30, provided with a peripheral annular rim 31. The diameter of this base 3 is adapted to the diameter of the burner body 2 (here to the ferrule 200), so that its peripheral rim 31 can be welded to the rear end 26 of the body 2, preferably inside this body 2, as is more clearly shown in the cross-section of the figure 5 . The base 3 and the body 2 are thus welded together in a gas-tight manner by a circular weld.

[0035] In addition, the base 3 is provided with at least one positioning finger 32, preferably three fingers, which project from the front face 301 of the disc 30, towards the interior of the cavity 20, when this base is assembled with the body 2. Their role will be detailed later. Facade flange 4:

[0036] As can be seen on the figure 5The front flange 4 is an annular element intended to be welded to the front end 25 of the burner body 2, in order to allow the connection of this body 2 to an air supply (not shown in the figures), necessary for gas combustion. The flange 4 includes, for example, a ring 40 welded inside said body 2 and which extends forwards by a radial collar 41 for fixing the body 2. Gas distributor 5:

[0037] The gas distributor 5 has the function of distributing the gas, in particular hydrogen, as close as possible to the orifices 21 of the burner body 2 and also of distributing the air circulating in the body 2, as will be described in detail later.

[0038] The distributor 5 is intended to be inserted axially into the burner body 2.

[0039] As this appears better on the Figures 1 And 3 à 5, the distributor 5 comprises a distributor body 50, the base 6 and the front flange 7.

[0040] The body 50 comprises a hollow cylinder 51, with a central longitudinal axis X1-X'1. This axis X1-X'1 is coaxial with the axis XX' of the burner 1 when the distributor 5 is mounted in the body 2. The cylinder 51 is provided with a plurality of radial branches 52, arranged in a star shape around the cylinder 51. The cylinder 51 defines a central cylindrical housing 53. Each branch 52 extends both radially outwards from the central axis X1-X1' and along the entire length of the cylinder 51.

[0041] As can be seen more clearly on the figure 7, each branch 52 comprises two flat walls 54, 54', parallel or substantially parallel to each other and spaced apart so as to provide between them a lamellar space 55 which opens at its radially internal end into the central cylindrical housing 53. The two walls 54, 54' are joined together, at their radially external ends, by a junction zone which defines the radially external longitudinal edge 56 of each branch 52. This edge 56 is preferably curved in cross-section, its concavity facing the lamellar space 55.

[0042] Preferably, the body 50 is made of a strip of sheet metal, bent to form the cylinder 51 and folded several times over itself to form each branch 52 opening into the housing 53.

[0043] As can be seen on the figure 3, each branch 52 is closed in a gas-tight manner at its front end 57 and at its rear end 57', for example by pinching the two walls 54, 54', then welding the edges of these walls together.

[0044] Finally, the radially external longitudinal edge 56 of each branch 52 is pierced with a plurality of orifices 58, each of them extending into a rim 59, (see the figures 6 And 7 ). The rim 59 surrounds the periphery of the orifice 58. Each rim 59 projects outwards from the radially outer face 560 of the edge 56. Each orifice 58 and its rim 59 have a central axis Z2-Z'2, which is normal to the outer face 560.

[0045] The rim 59 can advantageously be serrated so as to present notches 59' allowing to create turbulence at the exit of the rim 59 and thus improve the air / gas mixture which enters the orifice 21 and then the rim 22.

[0046] The orifices 58 and the rims 59 are, for example, "burst holes", obtained by stamping a sheet of metal. These orifices 58 are circular or substantially circular and the rims 59 are cylindrical or substantially cylindrical.

[0047] The distributor body 50 comprises a maximum of as many branches 52 as there are rows 24 of orifices 21 in the burner body 2. There may be fewer branches 52 than rows 24 of orifices, in which case only air will exit the rows 24 of orifices. Preferably, there are as many branches 52 as rows 24 of orifices.

[0048] The orifices 58 (and therefore the rims 59) are aligned axially along the longitudinal edge 56. Moreover, on each longitudinal edge 56 of each branch 52, there are as many orifices 58 as there are orifices 21 in a row 24 of the burner body 2. On a given longitudinal edge 56, the different orifices 58 can be regularly spaced from each other or, on the contrary, be grouped in several, so as to form a pattern, for example be grouped in pairs, as can be seen in the figures.

[0049] The bottom 6 is a disc whose outer diameter is equal to that of the inner diameter of the central cylindrical housing 53, and it is welded in a gas-tight manner to the cylinder 51, so as to close said housing 53.

[0050] The front flange 7 allows the distributor body 50 to be connected to a pressurized gas (hydrogen) supply source (not shown in the figures).

[0051] The front flange 7 preferably comprises a disc 70 with a central hole 71. The outer diameter of the disc 70 is equal to the inner diameter of the central cylindrical housing 53, and this disc 70 is welded at its periphery to the front end of the cylinder 51 in a gas-tight manner, as can be seen in the figure 3 . This disc 70 extends forward by a tube 72, with longitudinal axis X-X', which allows the connection of the front flange 7 to the gas supply source (not shown in the figures). Assembly.

[0052] The distributor 5 is inserted axially inside the cylindrical cavity 20 of the burner body 2, onto which the bottom 3 has been previously welded, then the front flange 4 is itself welded onto the burner body 2.

[0053] In this assembled position, it can be seen that the positioning fingers 32 are each positioned between two neighboring branches 52 and that they thus prevent any rotation of the distributor 5 around the longitudinal axis X-X', relative to the burner body 2.

[0054] The assembly of the distributor 5 and the body 2 is also made so that each orifice 58 (and therefore its rim 59) is coaxial with an orifice 21 and its rim 22 of the burner body 2, (see on the figure 6 the alignment of the Z1-Z'1 and Z2-Z'2 axes). Dimensions:

[0055] As can be seen on the figure 6 , the outside diameter D1 of the top 590 of each rim 59 of the distributor 50 is less than the inside diameter D2 of the orifice 21 of the burner body 2 opposite which it is positioned.

[0056] Furthermore, the height H1 between the apex 590 of each rim 59 (i.e., its outermost radial end) and the inner face 23' of the ferrule 2 is as small as possible so that the apex 590 is in the immediate vicinity of the inlet 210 of the orifice 21. Thus, the rim 59 acts as a micro-injector of gas that opens almost directly into the orifice 21, and the air / gas mixing takes place in the rim 22. The height H1 corresponds to the axial insertion clearance of the body 50 of the distributor 5 within the body 2, when both elements are cylindrical. Preferably, H1 is less than or equal to 0.1 mm.

[0057] The distributor body 50 and the burner body 2 are dimensioned so that there is an interval 27 for the passage of air between the top 561 of the longitudinal edge 56 of each branch 52 and the inner face 23' of the ferrule 2.

[0058] Preferably, the height H2 between the apex 561 of the edge 56 of each branch 52 and the inner face 23' of the ferrule is greater than or equal to 0.2 mm.

[0059] Preferably, the height H3 between the top of the free end 220 of a rim 22 of the distributor body 2 and the inner face 23' of the body 2 is between 0.8 and 2 mm.

[0060] According to other embodiments not shown in the figures, the burner body 2 and the gas distributor 5 could have shapes other than cylindrical.

[0061] The burner body 2 may, for example, comprise only a portion of its surface which acts as a combustion surface and in which the orifices 21, equipped with rims 22 as described previously, are drilled. Such a combustion surface may, for example, be flat, slightly curved, or V-shaped.

[0062] In this case, the shape of the distributor body 50 is adapted accordingly so that it can be inserted into the cavity 20 of the body 2. The body 50 still includes the branches 52 pierced with orifices 58 having rims 59, as described above, but these branches are not radial.

[0063] Finally, the characteristics described previously regarding the relative positioning of orifices 21 and 58 and the dimensions would be the same.

[0064] In the particular case where the burner body 2 and the gas distributor 5 are cylindrical, the gas burner 1 then further includes a gas pre-distribution device 8 and preferably a device 9 for setting in motion the gas entering the device 8. Gas pre-distribution device 8:

[0065] In the embodiment shown in particular on the Figures 1 And 4The gas pre-distribution device 8 comprises a series of annular washers 80, assembled against each other, as well as a front washer 81 (see Figures 1 And 4 ).

[0066] Each annular washer 80 has a central cylindrical opening 800, a flat front face 801, an opposite flat rear face 802 and a cylindrical lateral face 803.

[0067] On each annular washer 80, for example here on the front face 801, there are a series of straight grooves 804, cut into the thickness of the washer and which extend each radially from the central opening 800 to open onto the face 803. On each washer 80, there are as many grooves 804 as there are branches 52 in the distributor 5.

[0068] When the various washers 80 are pressed against each other, the rear face 802 of one comes into contact with the front face 801 of the neighboring washer, and this rear face 802 forms channels 805 with the various grooves 804 (see Figures 1 , 5 And 7 ). These canals 805 have openings 806 which open onto the lateral face 803. This gives us several successive tiers 807 of radial canals 805.

[0069] The front washer 81 comprises a central cylindrical opening 810, a flat front face 811, and an opposite flat rear face 812.

[0070] The 800 and 810 openings are coaxial and of the same diameter.

[0071] As this appears more clearly on the cross-section of the figure 4, an annular shoulder 814 is formed inside the central opening 810, so that this opening 810 has a rear portion 815 whose inner diameter is the same as that of the diameter of the openings 800 and a front portion 816 whose inner diameter is greater than that of the rear portion 815, so as to provide at the level of this front portion 816, a receiving housing 817 for the device 9 (which is preferably a propeller).

[0072] The annular shoulder 814 thus allows the propeller 9 to be axially locked towards the rear.

[0073] When the front washer 81 is pressed against the immediately adjacent washer 80, its rear face 812 comes into contact with the front face 801 of this washer and also delimits, with the grooves 804, radial channels 805. It would also be possible to provide the grooves 804 on the rear face 802.

[0074] The various washers 80 and the front washer 81 are assembled against each other and the gas pre-distribution device 8 thus formed is inserted axially and housed inside the housing 53 of the distributor 5, so that the rear face 802 of the last washer 80 comes into contact with the bottom 6 and the front face 811 of the front washer 81 is in contact with the disc 70. For this purpose, the outer diameter of the various washers 80 and 81 is equal, within the insertion clearance, to the inner diameter of the cylinder 51.

[0075] In this assembly position, which appears more clearly on the figure 5 We can see that the disc 70 cooperates with the housing 817 to axially lock the fixed propeller 9 forwards. The propeller is thus held between the front flange 7 and the washer 81.

[0076] The various washers 80 and 81 are positioned angularly with respect to the longitudinal axis X-X', so that their respective grooves 804 are superimposed and the external mouths 806 of the channels 805 form axial alignments 82, as can be seen on the figure 1 To this end, alignment features can be provided on the various washers 80 and 81 to ensure correct assembly. An alignment 82 is schematically represented by a dotted line on the figure 1 .

[0077] In addition, washers 80 and 81 are inserted into housing 53, so that each external mouth 806 of a radial channel 805 opens opposite a lamellar space 55. In other words, each alignment 82 is located opposite a branch 52.

[0078] According to a simplified embodiment, not shown in the figures, the gas pre-distribution device 8 can also be formed from a single solid cylindrical body instead of the various washers 80, 81. Such a solid cylindrical body has a central axial cylindrical opening corresponding to the central openings 800 and 810 and a plurality of radial channels 805 opening, on the one hand, into this central opening and, on the other hand, onto the outer surface 803 of the cylindrical body at the inlets 806. These various channels 805 are distributed over different stages 807 and supply gas to the branches 52 of the distributor body. Finally, such a single cylindrical body also has, at the front end of its central opening, a housing 817 for receiving the propeller 9.

[0079] It should be noted that it is not necessary to have as many stages 807 of channels as there are orifices 58 (or rims 59) on a branch 52. As a purely illustrative example, there are thus seven stages 807 of radial channels for fourteen rims 59 on each branch 52 in the embodiment shown in the drawings.

[0080] As can be seen on the figure 4 The fixed helix 9 comprises a central disc 91 from which extends a plurality of blades 92. The blades 92 are oriented with a pitch angle, which allows the incoming gas to be deflected to impart a helical motion to it inside the central openings 800 and 810. Materials:

[0081] The burner body 2, the ends 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 may be made of aluminum or composite material. The burner body 2 could also be made of refractory material. Functioning :

[0082] Tube 72 is connected to a pressurized gas supply, preferably hydrogen. Furthermore, the front flange 4 is connected to a pressurized air supply.

[0083] The path of the air inside the gas burner 1 will now be described. This path is symbolized by arrows labeled "a" with a numerical index.

[0084] Air enters the annular space around tube 72 (arrows a1 in figure 5), then distributes itself into air gaps within the spaces 520 formed between the branches 52 (arrows a2). The air then moves radially outwards along the walls 54 or 54' (arrows a3 on the figure 7 ) and also along an axial direction between the apex 561 of the edge 56 and the inner face 23' of the ferrule (arrows a4 on the figure 6 Finally, the air escapes through the edges 22 (arrows a5 on the figure 6 ).

[0085] The path of the gas inside the gas burner 1 will now be described. This path is symbolized by the arrows labeled "g" with a numerical index.

[0086] The gas enters tube 72 (arrow g1 on the figure 5 ), then is driven in a helical motion (arrow g2 on the figure 5) by the fixed helix 9. In the particular case where the gas is hydrogen, therefore an extremely volatile gas, this allows the hydrogen to be ideally distributed at the inlet of all the channels 805.

[0087] The gas is thus introduced into the various channels 805 (arrows g3 on the Figures 5 And 7 ) then exits these within the lamellar space 55 (arrows g4 on the Figures 5 And 7 ). The gas having been previously distributed in the different channels 805, each lamellar space 55 is supplied with gas homogeneously over its entire axial length.

[0088] The gas then exits through the orifices 58 and the rims 59 of the distributor 5 (arrows g5 on the figure 6 ), then penetrates the openings 21 and the edges 22 (arrows g6 on the figure 6) where it is mixed with air. It is therefore only inside these rims 22 that the air / gas mixing takes place and combustion occurs at the exit of the rims 22, therefore without risk of flashback in the spaces 520, nor in the radial branches 52.

[0089] The gas burner according to the invention can thus operate with hydrogen, although this gas is extremely volatile, while offering a power modulation range of at least 1 to 10, without risk of flame re-entry and therefore without risk of deflagration or detonation.

[0090] Finally, the measurements carried out showed that combustion with hydrogen takes place with an air lambda of 1.3 to 2 and a NOx emission level of 0.5 to 3 ppm.

[0091] In embodiments where the pre-distribution device 8 is not present, the gas exiting the tube 72 enters directly into the housing 53.

Claims

1. A deflagration-proof and detonation-proof surface combustion gas burner (1), comprising a burner body (2) made of metal or refractory material and a gas distributor (5), the burner body (2) delimiting an inner cavity (20) connectable to an air supply source and having an outer face (23) and an inner face (23'), the burner body (2) being perforated by a series of orifices (21), each of which is extended by a rim (22), which projects from this outer face (23) and the central axis (Z1-Z'1) of which is normal to this outer face (23), these orifices (21) being disposed in several rows (24) of aligned orifices (21), the gas distributor (5) comprising a distributor body (50) which delimits a housing (53) connectable to a gas supply source, the distributor body (50) comprising a plurality of longitudinal gas distribution branches (52), each branch (52) comprising two longitudinal walls (54, 54'), spaced apart from one another in such a way as to define between each other a longitudinal lamellar gas distribution space (55), which opens at its inner longitudinal end (550) into said housing (53), the two walls (54, 54') of each branch (52) meeting to form an outer longitudinal edge (56), a closed front end (57) and a closed rear end (57') of said branch (52), each branch (52) being perforated by a series of orifices (58) aligned along its outer longitudinal edge (56), each orifice (58) being bordered by a rim (59) which projects over the outer face (560) of said longitudinal edge (56) and each orifice (58) having a central axis (Z2-Z'2) normal to this outer face (560) of said longitudinal edge (56), the distributor body (50) being disposed in the inner cavity (20) of the burner body (2) so that each orifice (58) of the distributor body (50) is coaxial with an orifice (21) of the burner body (2), and the distributor body (50) and the burner body (2) being dimensioned so that the inner diameter D2 of an orifice (21) of the burner body (2) is greater than the outer diameter D1 of the apex (590) of the rim (59) of an orifice (58) of the distributor body (50) disposed facing this same orifice (21), so that there is a gap (27) for the passage of air between the apex (561) of the outer longitudinal edge (56) of each branch (52) and the inner face (23') of the burner body (2), and so that the apex (590) of the rim (59) of each orifice (58) is in immediate proximity to the inlet mouth (210) of the orifice (21) facing which it is placed, so that when the burner body (2) is connected to an air supply source and the distributor body (50) to a gas supply source, the air penetrates the burner body (2), circulates between the branches (52) of the distributor body (50) and in the gap (27) and escapes from the burner (1) through the rims (22) of the burner body (2), while the gas penetrates the housing (53) of the distributor body (50), circulates in the lamellar space (55) of the branches (52) then through the orifices (58) and rims (59) of this distributor body (50) and finally through the rims (22) of the burner body (2) within which it meets the air and is mixed with this one.

2. The gas burner (1) as claimed in claim 1, characterized in that at least one rim (22) of an orifice (21) of the burner body (2) and / or at least one rim (59) of an orifice (58) of the distributor body (50) is toothed so as to have notches (22', 59').

3. The gas burner (1) as claimed in claim 1 or 2, characterized in that the burner body (2) is formed from a cylindrical shell (200), shut off at its rear end (26) by a back wall (3) and the front end (25) of which is equipped with a front wall flange (4) connectable to the air supply source, in that the orifices (21) of the burner body (2) are fashioned in said shell (200) so that the rows (24) of orifices (21) extend axially over this shell, in that the distributor body (50) comprises a hollow cylinder (51) which delimits said housing (53) of this body, this housing (53) being central and cylindrical, in that the longitudinal gas distribution branches (52) extend radially around this cylinder (51), in that the distributor body (50) is shut off at its rear end by a back wall (6) and at its front end by a front flange (7), equipped with a central hole (71) connectable to the gas supply source, in that the gas distributor (5) comprises a gas pre-distribution device (8), which comprises a cylindrical body, equipped with an axial cylindrical central opening (800, 810) and several stages (807) of radial channels (805), each radial channel (805) extending from said central opening (800, 810) all the way to the outer surface (803) of said cylindrical body, and in that this gas pre-distribution device (8) is disposed coaxially inside the cylindrical housing (53) of the distributor body (50), so that its central opening (800, 810) is facing the central hole (71) of the flange (7) and each of its radial channels (805) opens into the lamellar space (55) of a branch (52) of the distributor body (50).

4. The gas burner (1) as claimed in claim 3, characterized in that the cylindrical body of the gas pre-distribution device (8) comprises several rear washers (80) and one front washer (81), these rear (80) and front (81) washers each having a cylindrical central opening (800, 810) and two opposing flat faces (801, 802, 811, 812), these central openings (800, 810) being of the same diameter, the front washer (81) and the rear washers (80) being assembled against one another so that their respective central openings (800, 810) are coaxial, the rear washers (80) having on one of their flat faces (801, 802) a series of radial grooves (804) which delimit, with the opposite face (802, 801) of a neighboring rear washer (80), said radial channels (805).

5. The gas burner (1) as claimed in claim 3 or 4, characterized in that the gas pre-distribution device (8) comprises a device (9) for moving the gas entering into this gas pre-distribution device (8), to impart to this gas a helical motion when it circulates inside the central opening (800, 810) of the cylindrical body.

6. The gas burner (1) as claimed in claim 5, characterized in that the device (9) for moving the gas is a fixed propeller.

7. The gas burner (1) as claimed in one of claims 3 to 6, characterized in that the shell (200) of the burner body (2) has a rear end (26), in that the back wall (3) of the burner body (2) comprises a solid disc (30) equipped with a peripheral annular rim (31) which is welded in a gastight manner to the rear end (26) of the shell (200), in that said solid disc (30) has a front face (301) and is equipped with at least one locator pin (32) which projects from this front face (301) and in that said at least one locator pin (32) is inserted between two neighboring branches (52) of the body (50) of the gas distributor (5).

8. The gas burner (1) as claimed in one of the preceding claims, characterized in that the distributor body (50) is formed from a metal sheet folded on itself to form the gas distribution branches (52).

9. The gas burner (1) as claimed in claim 8, characterized in that the front (57) and rear (57') ends of each branch (52) of the distributor body (50) are closed by pinching and welding.

10. The gas burner (1) as claimed in one of the preceding claims, characterized in that the gap (27) for the passage of air has a height (H2) greater than or equal to 0.2 mm.

11. The gas burner (1) as claimed in one of the preceding claims, characterized in that the ratio D2 / D1 of the inner diameter (D2) of an orifice (21) of the burner body (2) to the outer diameter (D1) of the apex (590) of the rim (59) of an orifice (58) disposed facing this same orifice (21) is between 1.2 and 4.

12. The gas burner (1) as claimed in one of the preceding claims, characterized in that the gas is hydrogen.

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