Burner, device and method for cooking ceramic articles

Abstract

Burner, apparatus and method for firing ceramic articles.burner (1) for firing ceramic articles (t), which can be installed in an industrial furnace (2) comprising a firing chamber (3); wherein said burner (1) comprises a mixing body (5); a spark generating device (8); a flame detection device (9); a first tubular discharge element (11), configured to be traversed by a fluid (f) flowing out of the mixing body (5) and having a first end (12) and a second end (14) opposite the first end (12); wherein the mixing body (5) comprises both a fuel partitioning system (fl), configured to divide the fuel into a plurality of first portions, and an oxidant partitioning system (ox), configured to divide the oxidant (ox) into a plurality of second portions, which are transported so as to be mixed, in at least two different stages, with the first portions.

Description

1 / 26 Burner, apparatus and method for firing ceramic articles. CROSS-REFERENCE WITH RELATED PATENT APPLICATIONS

[001] This patent application is related to Italian patent application no. 102021000013535 filed on May 25, 2021, the entire content of which is incorporated herein by reference. TECHNICAL FIELD OF THE INVENTION

[002] The present invention relates to an apparatus and a burner for firing ceramic articles. In particular, the invention finds an advantageous, though not exclusive, application suitable for use in firing ceramic articles to obtain tiles, to which explicit reference will be made in the following description, without thereby affecting generality. CONTEXT OF THE INVENTION

[003] The firing of ceramic articles to obtain tiles generally takes place in tunnel-type kilns, which are delimited by two opposite walls and a ceiling. These kilns are usually heated by two series of burners, each arranged on one side of the tunnel.

[004] Typically, the burners, which operate on natural gas (e.g., methane), are positioned on the side walls of the tunnel at various levels, and face the opposite wall.

[005] The firing cycle for ceramic articles is designed with great precision, and involves heating the ceramic articles from the kiln entrance, maintaining them inside the firing chamber at a predefined temperature, and cooling them in a controlled manner before they reach the kiln exit.

[006] Ceramic articles are generally transported on a large conveyor consisting of a series of ceramic rollers. As a consequence, it is important to ensure that the temperature inside the firing chamber is uniform across the entire width of the kiln.

[007] To that end, different types of industrial burners have been developed, as well as different burner arrangements within complex devices, in order to be Petition 870230108212, dated 07 / 12 / 2023, page 7 / 37 2 / 26 a more and more constant temperature is obtained inside the cooking chamber. In particular, especially in very wide tunnel ovens, there is usually an uneven distribution of temperature in the various longitudinal sections, and the local temperature peaks are determined based on the position of the burners.

[008] To overcome the problems mentioned above, different types of high-speed burners have been produced, which introduce combustion gases (and flame) deep inside the cooking chamber, in order to improve heat exchange inside it.

[009] However, as mentioned above, known types of ceramic burners are supplied with fossil fuels [methane, LPG (Liquefied Petroleum Gas)], which determines an anti-ecological use of non-renewable resources. For this reason, several environmentally sustainable solutions are being studied, such as the use of non-fossil fuels, one of which is hydrogen.

[010] Currently, however, the use of hydrogen is hampered by several factors. Firstly, this fuel causes high temperature peaks, which generate an increase in NOx production also relative to fossil fuels. In addition, hydrogen tends to generate a very unstable flame, which determines a much greater flame flashback compared to methane (or LPG), consequently generating a significantly retracted flame front (near the fuel supply line), which causes burner overheating, with the risk of causing uncontrolled explosions with possible damage to the burners and the cooking appliance.

[011] All these elements, among others, determine a lack of homogeneity in the temperature inside the kiln, which inevitably causes firing defects in the ceramic articles. In particular, the defects can be related to both size and shape, such as lack of flatness. Therefore, this results in an increase in rejects.

[012] The objective of the present invention is to produce an apparatus, a burner and a method that make it possible to overcome, at least partially, the drawbacks of the prior art, and that are also implemented in an easy and economical way. Petition 870230108212, dated 07 / 12 / 2023, page 8 / 37 3 / 26

[013] Examples of the prior art are disclosed in documents W02020183390, US9879855 and W02009047338. SUBJECT AND SUMMARY OF THE INVENTION

[014] According to the present invention, a burner, an apparatus and a method are provided for firing ceramic articles as claimed in the independent claims below and, preferably, in any of the claims directly or indirectly dependent on the independent claims.

[015] The claims describe preferred embodiments of the present invention, forming an integral part of the present description. BRIEF DESCRIPTION OF THE DRAWINGS

[016] The present invention will now be described with reference to the accompanying drawings, which illustrate some non-limiting examples of embodiments thereof, in which: - Fig. 1 is a front view in section of a first embodiment of an apparatus according to the present invention; - Fig. 2 is a schematic plan view of a portion of a second embodiment of an apparatus according to the present invention; - Fig. 3 is a schematic perspective view of part of the apparatus of Fig. 1 comprising a burner according to the present invention; - Fig. 4 is a front view in section of the part shown in Fig. 3; - Fig. 5 is a schematic perspective view of a part of the burner in Fig. 4; - Fig. 6 is a detailed longitudinal cross-sectional view of the burner section shown in Fig. 5; - Fig. 7 is a front cross-sectional view of a combustion head of the burner in Fig. 5; - Figures 8 and 9 are two front views in section of part of the combustion cylinder head shown in Figure 7; - Fig. 10 is a schematic perspective view of a part of a burner according to the present invention; and - Fig. 11 is a side cross-sectional view of a part of the discharge body shown in Fig. 10. Petition 870230108212, dated 07 / 12 / 2023, page 9 / 37 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[017] In fig. 1, reference number 1 indicates as a whole a burner for firing ceramic articles T according to a first aspect of the present invention.

[018] Burner 1 is preferably, but not necessarily, installable in an industrial furnace 2, in particular a tunnel furnace, comprising a cooking chamber 3.

[019] In particular, as illustrated in figs. 1 and 2, the ceramic articles T are moved by a transport system 4 along a transport path P.

[020] More precisely, T-type ceramic articles are any type of ceramic article that requires at least one firing in a kiln.

[021] In the non-limiting embodiment of figs. 1 and 2, the transport system 4 comprises a conveyor belt, on which the raw ceramic articles T to be fired are arranged, preferably in an orderly manner.

[022] According to some non-limiting embodiments not illustrated, the transport system 4 comprises a plurality of ceramic rollers (if necessary also moved at different speeds, to differentiate the firing of the articles).

[023] As illustrated in Figs. 1 to 5, the burner 1 comprises a mixing body 5, comprising, in turn, a duct 6 for feeding a fuel FL provided with a certain percentage of hydrogen (in particular greater than 50%, more precisely greater than 70%), a duct 7 for feeding an oxidizer, a spark generator device 8 for initiating combustion, and a flame detection device 9. In other words, the mixing body 5 is the part of the burner necessary to generate the air-gas mixture, which (after the spark is generated to obtain a flame) will fire ceramic articles T inside the furnace 2. In particular, the fuel introduced through the fuel feed duct 6 is mainly hydrogen (optionally mixed with natural gas, such as methane or LPG), while the oxidizer introduced through the oxidizer feed duct 7 is ambient air (for example, having about 21% oxygen). Petition 870230108212, dated 07 / 12 / 2023, page 10 / 37 5 / 26

[024] The burner 1 further comprises a tubular discharge element 11, designed (configured) to be traversed by a fluid F flowing out of the mixing body 5 (formed by the mixture of fuel and oxidant and / or a combustion thereof), being provided with an end 12 having an opening 13, into which at least a part of the mixing body 5 is inserted, and an end 14 opposite to end 12 having an opening 15.

[025] According to some non-limiting embodiments, the mixing body 5 is coupled to the tubular discharge element 11 by means of fastening elements. Advantageously, but not necessarily, as in the embodiment illustrated in figs. 4 and 5, the fastening elements are screws 16.

[026] In the non-limiting embodiment illustrated in Figs. 3 and 4, the mixing body 5 is partly inserted into the discharge element 11, and partly disposed outside the furnace 2. In particular, in the embodiment of Fig. 4, the discharge element 11 is inserted into a side wall 56 of the tunnel furnace 2. More precisely, the discharge element 11 extends completely inside the side wall 56. Alternatively, in other non-limiting embodiments, the discharge element 11 extends along the entire length of the side wall 56, also partly entering the cooking chamber 3 of the furnace 2.

[027] Advantageously, and as illustrated in the non-limiting embodiment of Fig. 4, the mixing body 5 comprises both an FPS fuel partitioning system for the FL fuel, configured to divide the FL fuel into a plurality of FL', FL', FL' portions, and an OPS oxidant partitioning system for the OX oxidant, configured to divide the OX oxidant into a plurality of OX', OX', OX' portions (see, for example, Fig. 5). The burner 1 is configured so that the plurality of FL', FL', FL' portions and the plurality of OX', OX', OX' portions are conveyed so as to be mixed in at least two (in particular three or more) stages (forming respective mixtures M', M', M').

[028] Advantageously, but not necessarily, the OPS oxidant partitioning system comprises a combustion head 10, disposed (at least partially) within the first tubular discharge element 11 (through the opening Petition 870230108212, dated 07 / 12 / 2023, page 11 / 37 6 / 26 13), and comprises one or more combustion chambers 22, 33, configured to each contain a different stage (or a mixture M1, M2) of flame combustion.

[029] Advantageously, but not necessarily, the FPS fuel partitioning system for FL fuel comprises an injection element 21, configured to inject at least the largest part FL' of the FL fuel downstream of the combustion head towards the end 14, i.e. towards the cooking chamber 3. In this way, most of the flame develops away from the end 12 of the burner 1, allowing, at the same time, the flame front to move towards the cooking chamber, and a reduction in the overheating of the mixing body and the discharge element 11.

[030] In particular, the tubular discharge element 11 is configured to contain a primary flame combustion stage F'.

[031] According to a preferred, but not limiting, embodiment illustrated in Figs. 4 to 9, the injection element comprises a tubular duct 23, in particular an axial duct (i.e., arranged parallel to a longitudinal axis AA of the burner), which passes through one or more combustion chambers 22, 33 from side to side, so as to transport the largest portion FL' of fuel (exceeding 50%, preferably 70% to 80%) downstream of the combustion head 10, advancing the largest part of the flame towards the cooking chamber 3.

[032] In the non-limiting embodiments of figs. 4 to 9, the tubular duct 23 has a constant cross-section, preferably circular. In particular, the tubular duct has a first cross-section having an internal diameter varying between 2 mm and 12 mm, in particular between 4 mm and 10 mm. In this way, it is possible to guarantee a high speed that favors a reduction / control of the flame flashback that normally causes problems in the case of hydrogen, also helping the rest of the burner to reach the speed required to introduce the combustion gases F deep inside the cooking chamber 3.

[033] In some non-limiting cases, the (length of) tubular duct 23 is configured so that the end 26' remains within the element of Petition 870230108212, dated 07 / 12 / 2023, page 12 / 37 7 / 26 tubular discharge 11. In particular, the (length of the) tubular duct 23 is configured so as to remain in the half of the tubular discharge element 11 furthest from the cooking chamber 3 (i.e., end 14). More particularly, the tubular duct 23 has, between its two ends 26 and 26', a length ranging from 40 mm to 150 mm, preferably from 60 mm to 110 mm.

[034] Advantageously, but not necessarily, as illustrated in the non-limiting embodiments of Figs. 6, 8 and 9, the tubular duct 23 has one or more fuel distribution openings 24 in the area of ​​each combustion chamber 22, 33, so as to inject at least one of the FL', FL portions into each of them. In particular, one or more distribution openings 24 are through holes 25 that connect an internal area of ​​the tubular duct 23 to a combustion chamber 22, 33.

[035] Advantageously, but not necessarily, the through holes 25 are radial holes, preferably ring-shaped, for example, extending radially from the AA axis. Preferably, the holes 25 have a diameter of less than 5 mm, in particular ranging between 1 mm and 3 mm.

[036] In some non-limiting cases, such as that illustrated in figs. 4 to 9, the tubular duct 23 comprises an end 26 connected to the fuel feed duct 6 for fuel FL, and an end 26' projecting into the tubular discharge element 11 towards end 14. In particular, the tubular duct 23 extends along a longitudinal axis of symmetry AA of the burner 1.

[037] Advantageously, but not necessarily, the fuel supply duct 6 for FL fuel comprises at least one narrow portion 17, having an internal diameter less than 10 mm, in particular varying from 4 mm to 8 mm. In particular, the narrow portion 17 has a smaller cross-section than that of the tubular duct 23. Thus, flame flashback is further avoided.

[038] In some non-limiting cases, not illustrated, the narrow portion 17 is configured to create a Venturi peak, drawing a portion of the oxidant back into the fuel feed duct, so as to add a stage to the flame combustion. Petition 870230108212, dated 07 / 12 / 2023, page 13 / 37 8 / 26

[039] Advantageously, but not necessarily, the burner 1 (mixing body 5) comprises a breech 54 (in particular made of aluminum or cast iron, and provided with the end portion of the fuel and oxidizer feed channels 6 and 7), which closes the burner 1 on the opposite side to the cooking chamber 3. In particular, the narrow portion 17 is formed as a single piece in the breech 54 of the mixing body 5. In particular, upstream and downstream of the narrow portion 17, the fuel feed duct 6 for the FL fuel has reamers.

[040] In some non-limiting cases, preferably in the presence of high percentages of hydrogen in the FL fuel, the breech 54 of the mixing body 5 does not have openings configured to premix the oxidizer OX and the FL fuel upstream of the oxidizer partitioning system. In other words, the breech 54 comprises a side wall 48 without openings. Thus, the narrow portion 17 also has the function of preventing flashback.

[041] In other non-limiting cases, not illustrated, preferably in the presence of small percentages of hydrogen in the FL fuel, the breech 54 has eccentric orifices, thanks to which the narrow portion 17 is configured to create a Venturi peak, drawing a portion of oxidant back into the fuel feed duct, so as to add a stage to the flame combustion.

[042] In particular, hydrogen causes a much greater flashback compared to methane (or LPG), and it has been surprisingly observed that by increasing the fuel feed rate FL through the narrow portion 17, it is possible to adequately avoid flashback, allowing proper control of the flame, while at the same time the fluid F is injected deeper into the cooking chamber 3.

[043] Advantageously, but not necessarily, and as illustrated in the non-limiting embodiments of Figs. 1 to 4, the burner 1 comprises a tubular discharge element 18 (illustrated, for example, by a dashed line in Fig. 4), which extends from the end 14 of the element 11 in the opposite direction with respect to the end 12, i.e., towards (more precisely, into) the chamber of Petition 870230108212, dated 07 / 12 / 2023, page 14 / 37 9 / 26 cooking 3. In other words, the discharge element 18 is arranged on the opposite side of the discharge element 11 with respect to the mixing body 5.

[044] In some non-limiting cases, the burner 1 comprises a suction element 19 designed (configured) to conduct at least part of the gases G present out of the burner 1, in particular out of the discharge element 11 and / or the discharge element 18 (more precisely within the cooking chamber 3), in the tubular discharge element 18, being provided with a plurality of openings 20 arranged between the tubular discharge element 11 and the tubular discharge element 18.

[045] Advantageously, but not necessarily, the tubular discharge element 14 is (completely) located within the cooking chamber 3, being, for example, coaxial to the tubular discharge element 11. In other words, the longitudinal axis of symmetry AA of the tubular discharge element 18 coincides with the longitudinal axis of symmetry AA of the tubular discharge element 11.

[046] Advantageously, and in a completely different way from the standards used in the ceramic market, the combustion head 10 is a multi-stage combustion head, that is, designed (configured) to divide the flame formation into several stages. In this way, it is possible to use the air staging technique.

[047] Advantageously, and in a very different way from the standards used in the ceramic market, the duct 23, together with the openings 24, assists the combustion head 10 in dividing the flame into different stages, in particular dividing the fuel FL. In this way, it is possible to use the fuel staging technique.

[048] By combining the techniques mentioned above, it is possible to use FL fuel with a substantial percentage of hydrogen and, at the same time, increase the flame speed to more than 160 m / s, in particular to more than 180 m / s, more precisely to about 200 m / s. In fact, the term high speed means, specifically in the field of burners, a flame speed equal to or greater than 150 m / s.

[049] Advantageously, but not necessarily, the combustion head 10 (with the tubular duct 23 inside it) is mounted at least partially inside the element Petition 870230108212, dated 07 / 12 / 2023, p. 15 / 37 10 / 26 tubular discharge 11, so as to be coaxial with it along the longitudinal axis of symmetry AA of burner 1.

[050] As illustrated in the non-limiting embodiments of Figs. 4 to 9, advantageously, the multi-stage combustion head 10 comprises (at least) a combustion chamber 22, designed (configured) to generate a first phase of flame combustion (in particular to generate the flame root) provided by the combination of portions FL' and OX', and (at least) a combustion chamber 33, which communicates with the combustion chamber 22 and is designed (configured) to generate a second phase of flame combustion (provided by the combination of portions FL and OX) that flows out of the combustion chamber 22. In particular, the combustion chambers 22 and 33 are configured to transport a secondary portion F (or secondary state) of the flame to the tubular discharge element 11 towards the end 14, and, in particular, through the suction element 19 towards the tubular discharge element 18.

[051] In the non-limiting embodiment of figs. 8 and 9, where two sections of the multi-stage combustion head 10 are illustrated in detail, the combustion chamber 22 comprises at least one inlet opening TJ and one outlet opening 28 (more precisely arranged on opposite sides of the combustion chamber 22).

[052] In some preferred, non-limiting cases, the burner 1 comprises additional openings 60 for feeding fuel FL (in particular the FL' portion), connecting the fuel feed duct 6 for fuel FL to the combustion chamber 22. In particular, the additional openings 60 for feeding fuel FL comprise axial through holes 61, preferably arranged as a ring (along mutually parallel directions) around the longitudinal axis of symmetry AA of the burner 1. More particularly, the additional openings 60 are made in the inlet opening 27, designed (configured) to communicate with the fuel feed duct 6 for fuel FL, and to receive a volumetric flow rate, more precisely variable, of said fuel FL. Preferably, the holes 25 have a diameter of less than 5 mm, in particular varying between 1 mm and 3 mm. Petition 870230108212, dated 07 / 12 / 2023, page 16 / 37 11 / 26

[053] The outlet opening 28 is facing the tubular discharge element 18 (i.e., the cooking chamber 3).

[054] Advantageously, but not necessarily, downstream of the narrow portion 17, but upstream of the combustion chamber 22, the mixing body comprises a first distribution chamber 59, configured to inject part of the FL fuel that passes through it via additional openings 60, and the remaining part into the tubular duct 23 via the end 26.

[055] In some non-limiting cases, combustion chamber 22 and combustion chamber 33 are coaxial with each other and are arranged along the longitudinal axis AA of burner 1.

[056] Advantageously, but not necessarily, the combustion chamber 22 comprises a side wall 29 having a circular cross-section. In particular, the cross-section of the side wall 29 converges radially as it approaches the outlet opening 28.

[057] Advantageously, but not necessarily, the combustion chamber 22 is equipped with one or more channels 30 to feed the oxidant OX, configured to transport a portion OX' of the oxidant OX to the combustion chamber 22, generating, together with the portion FL' of the fuel FL, a mixture of oxidant and fuel M'.

[058] In particular, channels 30 for feeding the oxidant OX are formed in such a way as to introduce the OX' part of the oxidant OX into the combustion chamber 22, with a velocity at least partially transverse in relation to a principal direction of the fuel corresponding to the longitudinal direction axis AA of the burner.

[059] According to the non-limiting embodiment of fig. 8 or 9, the side wall 29 of the combustion chamber 22 has a truncated cone shape comprising a larger base 31 and a smaller base 32, wherein the larger base 31 is located in the area of ​​the inlet opening 27, while the smaller base 32 is located in the area of ​​the outlet opening 28.

[060] Advantageously, but not necessarily, channels 30 for feeding the oxidant OX are formed in such a way as to introduce the OX' part of the oxidant OX into the chamber. Petition 870230108212, dated 07 / 12 / 2023, page 17 / 37 12 / 26 combustion 22, with a velocity having a direction parallel to the side wall 29 of the second combustion chamber.

[061] In the non-limiting embodiment of figs. 4 to 9, the burner 1 comprises a combustion chamber 33 disposed downstream of the combustion chamber 22, having an inlet opening 34 and an outlet opening opposite each other. The inlet opening 34 is configured to communicate with the outlet opening 28 and to receive the oxidant and fuel mixture M'. In particular, the outlet opening 35 is directed towards the tubular discharge element 1 (i.e., towards the cooking chamber 3).More precisely, the combustion chamber 33 comprises a side wall 36 having a circular cross-section, in particular cylindrical (i.e., parallel and constant to the longitudinal axis AA of the burner 1), provided with one or more channels 37 to feed the oxidant OX, and configured to allow the introduction of a portion OX of the oxidant OX into the combustion chamber 33, generating, together with the oxidant and fuel mixture M', an oxidant and fuel mixture M, generated inside the combustion chamber 33 and transported towards the tubular discharge element 18 (i.e., towards the cooking chamber 3).

[062] In the non-limiting embodiment of figs. 4 to 9, in particular as indicated in fig. 7, the channels 30 for feeding the oxidant have inclinations that differ from each other, for example, by an angle equivalent to 30°, or 20°. In this case, the side wall 29 of the combustion chamber 22 and the channels 30 for feeding the oxidant OX are parallel. Obviously, what has been explained above can also be applied to the channels 37 for feeding the oxidant OX.

[063] Advantageously, but not necessarily, the combustion chamber 33 comprises, in the side wall 36, a plurality of orifices 51 arranged in one or more radial rows, preferably with the same radial distance between them.

[064] In the non-limiting embodiment of fig. 6, the combustion head 33 comprises a crown 52, configured to regulate the introduction of the oxidant OX into the tubular discharge element 11 that does not pass through the combustion chambers 22 and 33. In particular, the crown 52 extends from the edge of the outlet opening 35 towards (up to) the inner wall of the tubular discharge element 11. Petition 870230108212, dated 07 / 12 / 2023, p. 18 / 37 13 / 26

[065] Advantageously, but not necessarily, and as illustrated in the non-limiting embodiment of Fig. 6, the crown 52 comprises grooves 53 (or any other type of opening) configured to transport a portion OX' of the oxidant to the tubular discharge element 11 downstream of the combustion chambers 22 and 33. In this way, together with the oxidant and fuel mixture M, and with the main portion FL' of the fuel, a mixture M' is generated which flows out of the tubular discharge element 11, through the suction element 19 towards the tubular discharge element 18. In particular, the primary flame F' of the burner 1 is generated.

[066] Advantageously, but not necessarily, and as illustrated in the non-limiting embodiment forms of figs. 1 to 4, the suction element 19 is designed (configured) to be disposed, at least partially (in some cases completely), within the cooking chamber 3.

[067] In the non-limiting embodiments of figs. 4, 10 and 11, the tubular discharge element 11, the tubular discharge element 18 and the suction element 19 together form a combustion block 38, illustrated schematically as a whole in fig. 10. In particular, a lateral surface 39 of the combustion block 38 is (at least) partially seamless. More particularly, the lateral surface 39 of the combustion block 38 is continuous in the sections not interrupted by the openings 20.

[068] Advantageously, but not necessarily, the combustion block 38 is produced as a single piece, in particular made of silicon carbide. More precisely, the longitudinal axis of symmetry of the combustion block 38 is the longitudinal axis of symmetry AA of the burner 1, the tubular discharge elements 11 and 18 and the multi-stage combustion head 10.

[069] Advantageously, but not necessarily, the 38 combustion block is produced by additive manufacturing, in particular 3D printing.

[070] In accordance with other non-limiting forms of incorporation, the combustion block 38 is formed by means of die casting techniques.

[071] In the non-limiting embodiments illustrated in the accompanying figures, the combustion block 38 is hollow and designed (configured) to allow the passage of a mixture (in particular the mixture M') generated by the mixing body 5 (i.e., by Petition 870230108212, dated 07 / 12 / 2023, page 19 / 37 14 / 26 combustion head 10). In particular, the aforementioned mixture M', M, M', once combustion has begun, becomes a flame.

[072] According to some non-limiting embodiments, the suction element 19 comprises, in particular, a Venturi tube.

[073] In the non-limiting embodiment of Figs. 10 and 11 (where Fig. 11 illustrates a detail of the suction element 19 of the embodiment of Fig. 11), the suction element 19 has a narrowing 40 disposed in the end area 14. In addition, the suction element 19 has at least one truncated cone-shaped portion 41, bounded by a larger base 42 and a smaller base 43. Finally, the tubular discharge element 1 has an open end 44 facing the suction element 19, and an open end 45 facing the center of the cooking chamber 3.

[074] Advantageously, but not necessarily, the openings 20 have an elongated shape, that is, they are grooves, which pass through the truncated cone-shaped portion 41 of the suction element 19 from side to side (transversely). In particular, the openings 20 are formed longitudinally in relation to the tubular discharge element 11 and the tubular discharge element 18.

[075] More specifically, the smaller base 43 of the said truncated cone-shaped portion 41 coincides with the narrowing 40, while the larger base 42 of the same truncated cone-shaped portion 41 coincides with the open end 44.

[076] Advantageously, but not necessarily, the openings 20 are formed in the truncated cone-shaped portion 41 of the suction element 19. In particular, they pass through the truncated cone-shaped portion 41 of the suction element 19 from side to side (transversely).

[077] Advantageously, but not necessarily, and as illustrated in figs. 4, 10 and 11, the suction element 19 comprises reinforcing ribs 46. Thanks to these ribs 46, it is possible to extend the discharge element 18 as desired without the risk of the combustion block 38 breaking in the area of ​​the portion having the smaller section, that is, in the area of ​​the suction element 19. Petition 870230108212, dated 07 / 12 / 2023, page 20 / 37 15 / 26

[078] Advantageously, but not necessarily, the suction element 19 has a circular cross-section.

[079] Advantageously, but not necessarily, the suction element 19 has a circular cross-section having a variable diameter.

[080] In particular, the cross-section TT (fig. 11) of the narrowing 40 has a diameter less than two-thirds of the diameter of the discharge element 18 and the diameter of the discharge element 11. More particularly, the cross-section TT (fig. 11) of the narrowing 40 has a diameter less than half the diameter of the discharge element 18 and the diameter of the discharge element 11. The more the diameter of the narrowing 40 decreases, relative to the diameter of the discharge element 11, the greater the variation in the mixing velocity M' that circulates inside the discharge element 11 during use.

[081] Advantageously, but not necessarily, the cross-section TT (fig. 11) of the narrowing 40 has a diameter less than one third of the diameter of the discharge element 18 and the diameter of the discharge element 11. In particular, the cross-section TT (fig. 12) of the narrowing 40 has a diameter greater than one sixth of the diameter of the discharge element 18 and the diameter of the discharge element 11.

[082] Advantageously, but not necessarily, the diameter of the 40 narrowing is less than 30 mm, in particular equal to or less than 25 mm. In more detail, the diameter of the 40 narrowing varies from 5 mm (in particular from 10 mm; more particularly from 20 mm) to 60 mm (in particular up to 40 mm; more particularly up to 30 mm). This feature also allows for the prevention of flashback and consequently better combustion management with very hydrogen-rich FL fuel mixtures.

[083] Advantageously, but not necessarily, the diameter of the discharge element 11 and the diameter of the discharge element 18 vary from 20 mm (in particular from 40 mm; more particularly from 50 mm) to 200 mm (in particular up to 120 mm; more particularly up to 100 mm).

[084] According to a preferred, but not limiting, embodiment as illustrated in Figs. 4 to 7, the spark-generating device 8 comprises an electrode of Petition 870230108212, dated 07 / 12 / 2023, p. 21 / 37 16 / 26 spark (in particular parallel to the side wall 48 of the breech 54), and the flame detection device 9 comprises a UV detection probe 50. In particular, the UV probe 50 is arranged along the longitudinal axis AA of the burner on board the breech 54, that is, on board the mixing body 5.

[085] Advantageously, but not necessarily, the flame detection device 9 (more precisely the UV detection probe 50) is configured to receive a UV beam (ultraviolet radiation) from the flame passing through the tubular discharge element 11. During use, the UV detection probe 50 provides data relating to the state of the flame generated by the burner, through which it is possible to properly regulate the flow rate of the fuel FL and / or the oxidant OX. Furthermore, in the case of flameless combustion, the UV probe 50, when operating at full capacity, is deactivated, as it is no longer able to detect any flame, since the flame front is diluted inside the oven's cooking chamber.

[086] According to a second aspect of the present invention, an industrial apparatus 55 is provided for firing ceramic articles, in particular according to the preceding description.

[087] With particular reference to figs. 1 and 2, an industrial apparatus according to the present invention is indicated as a whole by reference number 55.

[088] According to some non-limiting embodiments, ceramic articles T are, once fired, tiles. In particular, ceramic articles T are raw at the entrance of apparatus 55, and are fired at the exit.

[089] The industrial apparatus 55 comprises the furnace 2 (described above), in particular a tunnel furnace, having at least one side wall 56 that delimits the cooking chamber 3, and having an inner surface 57 inside the cooking chamber 3 and an outer surface 58 outside the cooking chamber 3.

[090] The industrial apparatus 55 further comprises the transport system 4 described above, in particular horizontal, configured to transport the plurality of ceramic articles T along the transport path P within the firing chamber 3 (from the entrance to the exit of the firing chamber 3). Petition 870230108212, dated 07 / 12 / 2023, page 22 / 37 17 / 26

[091] Apparatus 55 comprises a burner 1, which in turn comprises a tubular discharge element 11, and preferably, but not necessarily, a tubular discharge element 18 and a gas suction element 19 G.

[092] Advantageously, but not necessarily, apparatus 55 comprises a (hydrogen) burner 1 according to the description above.

[093] Advantageously, apparatus 55 comprises a hydrogen feed system configured to inject hydrogen or a mixture comprising hydrogen into the feed duct 6 for fuel FL.

[094] Advantageously, but not necessarily, the suction element 19 is disposed between the discharge element 11 and the discharge element 18, and is disposed at least partially (in some non-limiting cases, also completely) within the cooking chamber 3.

[095] In particular, the suction element 19 is configured to conduct at least part of the gases G present in the cooking chamber 3 to the discharge element 18. In this way, it is possible to use the residual oxygen within the cooking chamber 3, and to complete the combustion of the gases G that were not fully burned with a first pass within the burner 1, that is, by means of a primary combustion F'. Furthermore, the gases G (presumably also considering the fact that they have a relatively high temperature) contribute to improving the combustion efficiency.

[096] Primary combustion means combustion generated by the mixing body 5 (in particular by the combustion head 10), whose flame flows through the discharge element 11.

[097] Advantageously, but not necessarily, and as illustrated in the non-limiting embodiment of Fig. 4, the suction element 19 is disposed in the internal surface area 57 of one of the side walls 56.

[098] In particular, the suction element 19 is configured to create a depression between the discharge element 11 and the discharge element 18, so as to conduct at least part of the gases G present in the cooking chamber 3 to the discharge element 18. In other words, in the non-limiting embodiments illustrated Petition 870230108212, dated 07 / 12 / 2023, page 23 / 37 18 / 26 in the attached figures, the depression is generated by the Venturi effect. The high flame speed generated by the multi-stage combustion head 10 determines the surprising synergistic effect of increasing the suction capacity of the suction element 19.

[099] According to the non-limiting embodiment of fig. 2, the apparatus 55 comprises a plurality of burners 1 arranged in series along a direction DD parallel to the transport path P. In particular, the burners 1 are arranged at various levels within at least one of the walls 56 of the furnace 2.

[0100] In the non-limiting embodiments of figs. 1 to 4, the burner 1 is coupled, by means of fastening elements, to the wall 56 of the furnace 2. In particular, the discharge element 11 is inserted into the wall 56.

[0101] In the non-limiting embodiment of fig. 1, the burners 1 are oriented in a direction DP transverse (in particular, perpendicular) to the direction DD (and therefore to the transport path P).

[0102] Advantageously, but not necessarily, the tubular element 11 of burner 1 is installed so as to pass, at least partially (in particular completely and transversely) through one of the side walls 56 of oven 2. In this way, the flame produced by burner 1 will flow directly into the interior of the cooking chamber 3 of oven 2.

[0103] In particular, axis AA is perpendicular to transport path P. More particularly, axis AA is also perpendicular to side wall 56 of industrial tunnel furnace 2.

[0104] Advantageously, but not necessarily, the tubular discharge element 1 of burner 1 is disposed completely inside the cooking chamber 3.

[0105] According to some non-limiting embodiments not shown, the discharge element 11 of burner 1 is installed so as to project partially into the cooking chamber 3.

[0106] Advantageously, but not necessarily, the openings 20 are arranged at least partially (in particular completely) within the cooking chamber 3.

[0107] Advantageously, but not necessarily, the appliance 55 (or each burner 1) comprises at least one electronic control unit 62, configured for Petition 870230108212, dated 07 / 12 / 2023, page 24 / 37 19 / 26 control burner 1 in order to change the cooking chamber 3 configuration from flame cooking to flameless cooking. In particular, the electronic control unit 62 is configured to, upon reaching a predefined temperature, change from flame mode to flameless mode. More precisely, the predefined temperature is higher than the auto-ignition temperature of the fuel mixture. Through this cyclical (intermittent) control of the oxidant OX and fuel FL feed to burner 1, it is possible to produce flameless combustion even using fuels such as hydrogen, which tend to reform the flame front suddenly and undesirably within the burner, where, in this case, the flameless mode is prolonged over time even at low capacities (where a reduction in the intensity of the flame pulse causes the occurrence of suitable conditions for the formation of the flame front).

[0108] In particular, the electronic control unit 62 is configured to cyclically, during the flameless cooking setting, reduce (preferably interrupt) the supply of FL fuel and optionally OX oxidant, selectively inhibit flame control (by means of the detection device 9), and restore the supply of FL fuel and optionally OX oxidant, allowing the burner 1 to ignite in a flameless mode. By using flameless combustion, i.e., combustion that exploits the fact that the temperature inside the furnace is higher than the auto-ignition temperature of the fuel, it is actually possible to drastically reduce the NOx emissions normally generated in the combustion of hydrogen-rich mixtures (and in general in combustions with high flame peaks), thus allowing the use of an environmentally sustainable fuel with low emissions.In particular, the alternating combination of flame mode and flameless mode makes it possible to compensate for the high flammability and propagation (flame flashback) of hydrogen.

[0109] In particular, but without limitation, the electronic control unit 62 is configured to control the appliance 55 so as to bake the T-tiles only in the flameless configuration. Petition 870230108212, dated 07 / 12 / 2023, page 25 / 37 20 / 26

[0110] Advantageously, but not necessarily, and as illustrated in the non-limiting embodiment of Fig. 1, the apparatus 55 comprises at least two temperature control devices 63, in particular at least two double-filament thermocouples 64, arranged at at least two different significant points of the oven 2. These two points make it possible to ensure that the temperature is sufficiently higher than the auto-ignition temperature of the fuel mixture at all points in the cooking chamber.

[0111] Advantageously, but not necessarily, in the event that the temperature detected by the two thermocouples 64 falls below the auto-ignition temperature, the flame is ignited and lit again, i.e., the electronic control unit 62 immediately restores the flame operating mode of burner 1.

[0112] According to another aspect of the present invention, a method is provided for firing ceramic articles transported within a tunnel kiln.

[0113] The method comprises at least one stage of feeding a burner, as described above, with a fuel comprising at least a hydrogen percentage greater than 20%, in particular greater than 50%, more particularly greater than 70%. These fuel mixtures are possible thanks to the particular geometry of the burner described above, in particular thanks to the multi-stage combustion head 10 in combination with the injection element 21. Furthermore, the dimensions of the narrow section 17, the geometry of the chambers 22 and 33, i.e., the size and number of openings 24 and 60, and of the tubular discharge element 1 and the suction element 19, synergistically determine the important technical effect of reducing the environmental impact, allowing the use of a hydrogen-rich mixture as fuel and a reduction of NOx, respectively.

[0114] In some non-limiting cases, FL fuel comprises a hydrogen percentage greater than 90%. In particular, the fuel is 100% hydrogen.

[0115] The method also includes the step of simultaneously feeding burner 1 with oxidant OX and igniting (lighting) the flame (by means of the spark generator device 8), which extends at least partially inside the burner and the cooking chamber 3 of the oven 2. Petition 870230108212, dated 07 / 12 / 2023, page 26 / 37 21 / 26

[0116] Once the flame ignition is complete, the method provides for flame control by feedback thanks to the detection device 9.

[0117] Advantageously, but not necessarily, the method comprises the additional steps of, after the firing chamber 3 of furnace 2 has reached a predefined temperature (in particular exceeding the auto-ignition temperature of fuel FL), cyclically extinguishing the flame by decreasing (or interrupting) the supply of fuel FL, and, if necessary, of oxidant OX; preferably disabling the aforementioned flame feedback control; restoring the supply of fuel FL, in particular also of the oxidant, generating flameless combustion inside tunnel furnace 2 for firing the ceramic articles T. In these non-limiting cases, this alternating flameless combustion step (where burner 1 is fed alternately and cyclically) represents firing at full operational capacity of furnace 2. In particular, the method provides for the change from flame mode to flameless mode when a predefined temperature is reached.More precisely, the preset temperature exceeds the auto-ignition temperature of the fuel mixture.

[0118] Advantageously, but not necessarily, the method provides for the firing of the T-tiles only after the flameless configuration has been established. That is, burner 1 is fed with oxidant OX and fuel FL cyclically without igniting the flame, simultaneously energizing and de-energizing (opening and closing) a fuel solenoid valve (especially two solenoid valves in series, as per current legislation) and an air solenoid valve. In particular, the energizing and de-energizing steps of the solenoid valves (i.e., feeding and interrupting the oxidant and fuel) are preferably performed after the electronic control unit 62 has extinguished the flame in burner 1, and inhibited the spark electrode 49 and the UV detection probe 50 of the flame (with the flame front no longer located in burner 1, but diluted in chamber 3 of the furnace).More specifically, through the aforementioned solenoid valves, the supply of oxidant OX and fuel FL is digitally controlled (ON / OFF), that is, it goes from the maximum flow rate to zero, and vice versa. In this way, it is possible to prevent the formation of corrosion. Petition 870230108212, dated 07 / 12 / 2023, page 27 / 37 22 / 26 of a fixed flame front anchored inside the burner 1. In more detail, this effect is due to the fact that a very high impulse is given to feed the flame, so as to avoid the formation of the flame front in the burner, which is therefore diluted directly in the cooking chamber 3.

[0119] In other non-limiting cases, according to the same principle explained above, the method maintains, by means of the control unit 62, the supply of oxidant OX, and the cyclic supply and interruption of only the fuel FL. In this way, it is possible to maintain a constant pressure state in chamber 3 of furnace 2, without oscillation of the gas flow in the chimney. In addition, a possible reignition of the flame front inside burner 1 is also avoided.

[0120] In the flameless stage, the flame is diluted directly in the furnace chamber, with the combustion products already present in chamber 3 having a lower oxygen content than the combustion air. In other words, in this way, the mixture of oxidant and fuel that flows from burner 1 towards cooking chamber 3 is oxidized inside chamber 3.

[0121] Therefore, it is possible to avoid the presence of temperature peaks (which are among the main causes of NOx production) compared to conventional flame-only solutions. This, in turn, results in a reduced thermal load on the components of burner 1 (for example, in the combustion head 10, in the tubular duct 23, in the mixing body 5, in the combustion block 38, in the fuel and oxidant tubes, etc.). Simultaneously, a substantial reduction in heat loss caused by the burner is obtained, thus improving the efficiency of furnace 2. Additionally, without a flame, burner 1 will be quieter, thus also reducing the noise pollution it produces.

[0122] Finally, the higher speed achieved by the narrow portion 17 in combination with the tubular duct 23, to prevent increased flame flashback by hydrogen, allows for increased penetration of the combustion gases flowing from the burner 1 to the cooking chamber 3, which determines greater uniformity in the cooking of articles T. Petition 870230108212, dated 07 / 12 / 2023, page 28 / 37 23 / 26

[0123] During use, the spark generator device 8 (in particular the spark electrode) generates a spark which, together with the fuel FL flowing from duct 6 and the oxidizer OX flowing from duct 7, determines the generation of the flame. In particular, the OX' portion of the oxidizer and the fuel FL' generate the mixture M' within the combustion chamber 22, which defines a first stage of the flame and continues towards the combustion chamber 33, within which the mixture M', the FL portion of the fuel and the OX portion of the oxidizer form the mixture M, which defines a second stage of the flame. The mixture M enters the tubular discharge element 11, where it mixes with the OX' portion of the oxidizer OX and with the FL' portion of the fuel FL exiting at the end 26' forming the fluid F (and the primary flame F').Therefore, the mixing body 5 generates a mixture that is at least partially burned, that is, a flame, whose fluids F pass through the discharge element 11, which introduces them into the suction element 19, which in turn transports them (along with the gases G aspirated from inside the combustion chamber 3) to the discharge element 18. The latter introduces the flame into the combustion chamber 3.

[0124] The combustion products emitted by burner 1 are not fully burned during their first pass through the discharge element 11, but combustion is increased (completed) thanks to the continuous recirculation of gases G (present inside the cooking chamber 3) through the suction element 19 into the discharge element 18. In other words, burner 1 generates, by means of the spark generator device 8, a primary combustion of the gases introduced by ducts 6 and 7 (fuel and oxidant) and a secondary combustion of the same, taking advantage of the gases G recirculated from inside the cooking chamber 3 and not completely burned (in which residual oxygen is present), drawn in by the suction element 19. In particular, primary combustion occurs within the discharge element 11, and secondary combustion occurs within the discharge element 18.

[0125] In the non-limiting embodiments illustrated in the attached figures, the suction element 19 (due to the high velocity of the fluid F generated by the mixing body 5) determines an increase in turbulent movements within the cooking chamber 3. Furthermore, the secondary combustion that occurs within the discharge element 18 generates Petition 870230108212, dated 07 / 12 / 2023, pp. 29 / 37 24 / 26 an additional increase in heat exchange, particularly through radiation, due to the heating of the aforementioned discharge element 18. This results in an increase in the total heat transfer coefficient in the ceramic articles T, and greater temperature homogeneity within the firing chamber 3.

[0126] Therefore, it is evident that, using an apparatus 55 or a set of burners 1 according to the present invention, greater temperature uniformity is obtained along the width of the cooking chamber 3 of the oven 2. In particular, the temperature near the wall 3 is considerably increased, thanks to the turbulence generated by the suction element 19 (thanks to the additional speed allowed by the multi-stage combustion head 10) and the contribution of the radiation provided by the discharge element 18 near the aforementioned wall 3. Furthermore, the temperature in the center of the oven is increased compared to conventional solutions, due to the use of the discharge element 18, which allows the combustion block 38 to reach greater depths within the oven 2. Therefore, the flame exiting the said discharge element 14 is emitted at a greater depth compared to conventional solutions.

[0127] It is important to note that the temperature peak near the outlet of burner 1 is also (at least partially) flattened.

[0128] Although the invention described above refers particularly to a specific example of an embodiment, it should not be considered limited to that example of an embodiment, and to all variants, modifications or simplifications covered by the appended claims, such as a different geometry of the combustion head 10, of the injection element 21, of the chambers 22 and 33, of the combustion block 38 and in particular of the suction element 19, a different method of suction of the gases G near the inner surface 57 of the side wall 56, a different arrangement of the burners 1 within the apparatus 55 (both with respect to position and alignment), a different transport system 4, etc., which are within its scope of protection.

[0129] The appliance and burner described above offer numerous advantages.

[0130] Firstly, the production and assembly of burner 1 are simplified in relation to prior art solutions comprising more components. Petition 870230108212, dated 07 / 12 / 2023, pages 30 / 37 25 / 26 Furthermore, burner 1, due to its geometry and penetration into the cooking chamber 3, can be easily installed as a replacement for a standard architecture (as an improvement).

[0131] Additionally, the presence of the discharge element 18 inside chamber 3 and the suction element 19, close to the inner surface 57 of the wall 56 and not inside the wall 56, together with the fuel staggering, avoids problems related to overheating of this wall 56, usually made of bricks, which would cause overheating, with possible breakage, of the combustion block 38, and / or overheating of the mixing body 5 (usually made of metal), which in turn would generate a risk of burns for the operators and a considerable loss of energy.

[0132] Other advantages of the present invention lie in the reduction of losses, the increase in combustion (the recirculation obtained, of at least 50% of the combustion products of the burner, allows the use of adjustments with reduction of the oxidant, taking advantage of the residual oxygen present in the recirculated gases G) and the uniformity of the temperature inside the cooking chamber 3, determining, by the apparatus 55 and the burner 1, according to the present invention, the need for a smaller quantity of gas (particularly useful in the case of fuels whose management is problematic, such as hydrogen) to be introduced into the burner 1 to maintain a certain temperature, in relation to the solutions of the prior art.

[0133] Additionally, the use of a multi-stage combustion head 10, in combination with the injection element 21, allows a reduction in flame temperature peaks, which are the main reason for the creation of nitrogen oxides. Therefore, the present invention determines a reduction of nitrogen oxides (NOx), mainly below 50 ppm, using natural gas.

[0134] Furthermore, the synergistic effect between the multi-stage combustion head 10, the injection element 21 and the combustion block 38 allows the use of much smaller outlets, making it possible to achieve a flame speed of around 200 m / s.

[0135] The present invention is configured to be supplied by different types of gas (for example methane or LPG), and is designed to operate with fuels Petition 870230108212, dated 07 / 12 / 2023, pages 31 / 37 26 / 26 environmentally sustainable, such as hydrogen-enriched methane, pure hydrogen, etc. In particular, the structure of the oxidant feed channels varies depending on the fuel used.

[0136] Compared with a conventional burner, the flame of the burner according to the present invention is more homogeneous and less turbulent. This characteristic allows the flame to remain elongated and propagate over a greater extent without spreading excessively into the surrounding environment (i.e., in the firing chamber 3). This effect ensures that the ceramic articles passing through during firing are not greatly affected by direct flame interaction, thus avoiding any technological defects (color tones, different calibers, etc.) due to temperature peaks, often caused by direct flame interaction.

[0137] Furthermore, the strong recirculation created by the very high flame speed of burner 1, comprising a combustion block as described above, dilutes the flame temperature (i.e., decreases peaks, increasing the median) and increases the convective heat exchange coefficient with the ceramic articles T. For this reason, compared to a conventional architecture and having the same power, the present invention allows heating the material more without attacking it with temperature peaks in the flame area, and oxidizing the organic substances contained in the ceramic articles T more homogeneously, thus avoiding the occurrence of a darker color in the inner portion of a sectioned article. In this way, the risk of the ceramic articles T exploding in a preheating zone of furnace 2, for example, when articles with excessive moisture content are fired, is also partially inhibited.

[0138] Finally, thanks to the special structure of the injection element, a large part of the flame is generated downstream of the combustion head, reducing the problems related to hydrogen flame flashback and flame front advance. Petition 870230108212, dated 07 / 12 / 2023, pages 32 / 37

Claims

1 / 5 Claims 1. BURNER (1) FOR FIRING CERAMIC ARTICLES (T), which can be installed in an industrial furnace (2) comprising a firing chamber (3), such burner (1) comprising: a mixing body (5) including, in turn, at least one duct (6) for feeding a fuel (FL) provided with a percentage of hydrogen, and at least one duct (7) for feeding an oxidizer (OX); a spark generating device (8) for initiating combustion; a flame detection device (9); a first tubular discharge element (11), configured to be traversed by a fluid (F) flowing out of the mixing body (5), being provided with a first end (12), in which at least part of the mixing body (5) is inserted, and a second end (14), opposite the first end (12);the said burner (1) being characterized in that the mixing body (5) comprises both a fuel partitioning system (FPS) for the fuel (FL), configured to divide the fuel (FL) into a plurality of first portions (FL', FL, FL'), and an oxidant partitioning system (OPS) for the oxidant (OX), configured to divide the oxidant (OX) into a plurality of second portions (OX', OX, OX'), which are transported so as to be mixed, in at least two different stages, with the first portions.

2. BURNER (1), according to claim 1, characterized in that the oxidant partitioning system (OPS) for the oxidant (OX) comprises a combustion head (10), at least partially disposed within the first tubular discharge element (11) and comprising one or more combustion chambers (22, 33), each configured to contain different stages (M', M) of the combustion of a flame; wherein the fuel partitioning system (FPS) for the fuel (FL) comprises an injection element (21), configured to inject at least the greater part (FL') of the fuel (FL) downstream of the combustion head (10) towards the second end (14); in particular, with the first tubular discharge element (11) being configured to contain a primary stage (F') of the flame combustion. Petition 870230108212, dated 07 / 12 / 2023, p. 33 / 37 2 / 5 3. BURNER (1), according to claim 2, characterized in that the injection element (21) comprises a tubular duct (23), in particular axial, which passes through said one or more combustion chambers (22, 33) from side to side; wherein, in particular, the fuel supply duct (6) comprises at least one narrow portion (17) having a cross-section smaller than that of the tubular duct (23).

4. BURNER, according to claim 3, characterized in that the tubular duct (23) has a constant cross-section, in particular circular.

5. BURNER, according to claim 4, characterized in that the tubular duct (23) has a first cross-section having a diameter ranging between 2 mm and 12 mm, in particular between 4 mm and 10 mm.

6. BURNER, according to any one of claims 3 to 5, characterized in that the tubular duct (23) has one or more fuel distribution openings (24) in the area of ​​each combustion chamber (22, 33), so as to inject at least one of the second portions (FL', FL) into each of them.

7. BURNER, according to claim 6, characterized in that one or more openings (24) are through holes (25) that connect an internal area of ​​the tubular duct (23) to a combustion chamber (22, 33).

8. BURNER, according to claim 7, characterized in that the through holes (25) are radial holes, in particular arranged in a ring shape.

9. BURNER, according to any one of claims 3 to 6, characterized in that the tubular duct (23) comprises a first end (26), connected to the fuel feed duct (6) for the fuel (FL), and a second end (26'), which projects into the first tubular discharge element (11) towards the second end (14); in particular, the tubular duct (23) extends along a longitudinal axis of symmetry (AA) of the burner (1).

10. BURNER (1), according to any of the preceding claims, characterized in that the fuel supply duct (6) comprises at least one narrow portion (17) having a cross-sectional diameter less than 10 mm, in particular ranging from 4 mm to 8 mm. Petition 870230108212, dated 07 / 12 / 2023, page 34 / 37 3 / 5 11. BURNER (1), according to claim 10, characterized in that the narrow portion (17) is formed as a single piece in a breech (54) of the mixing body (5), in particular with the breech (54) of the mixing body (5) not having any opening configured for premixing the oxidant (OX) and the fuel (FL) upstream of the oxidant partitioning system (OPS).

12. BURNER (1), according to any of the preceding claims, characterized in that the combustion head (10) comprises at least one first combustion chamber (22), configured to generate a first phase of flame combustion (M'), and a second combustion chamber (33), which communicates with the first combustion chamber (22) and is configured to generate a second phase of flame combustion (M) outside the second combustion chamber (33); with the first and second combustion chambers (33) being configured to carry part of the flame into the first tubular discharge element (11) towards the second end (14); in particular, with the burner (1) further comprising fuel distribution openings (60) connecting the fuel supply duct (6) to the fuel (FL) to the first combustion chamber (22);wherein, in particular, the said other fuel distribution openings (60) comprise axial orifices, preferably arranged as a crown around a longitudinal axis of symmetry of the burner (1).; 13. BURNER (1), according to any of the preceding claims, characterized in that the flame detection device (9) comprises a UV probe (50), in particular disposed along a longitudinal axis (AA) of the burner aboard a breech (54) of the mixing body (5).

14. BURNER (1), according to any of the preceding claims, characterized by further comprising at least one second tubular discharge element (18), extending from the second end (14) towards the opposite side in relation to the first end (12); and a suction element (19), configured to conduct at least part of the gases (G) present outside the burner (1) to the second tubular discharge element (18), having Petition 870230108212, dated 07 / 12 / 2023, page 35 / 37 4 / 5 or more openings (20) arranged between the first (11) and the second tubular discharge elements (18).

15. INDUSTRIAL APPARATUS (55) FOR FIRING CERAMIC ARTICLES (T), comprising a tunnel kiln (2) having at least one side wall (56), which at least partially delimits a firing chamber (3), and having an inner surface (57) inside the firing chamber (3) and an outer surface (58) outside the firing chamber (3); a transport system (4), configured to transport a plurality of ceramic articles (T) along a transport path (P) inside the firing chamber (3); said apparatus (55) being characterized by comprising at least one burner (1) as described in any one of claims 1 to 14; said industrial apparatus (55) comprising at least one hydrogen feed system, configured to inject hydrogen or a mixture comprising hydrogen into the fuel feed duct.

16. APPARATUS (55), according to claim 15, characterized in that the suction element is disposed between the first tubular discharge element (11) and a second tubular discharge element (18) and at least partially within the cooking chamber (3); said suction element (19) being configured to conduct at least part of the gases (G) present in the cooking chamber (3) to the second discharge element (18); wherein, in particular, the suction element (19) is disposed in the area of ​​the inner surface (57) of the side wall (56), and said suction element (19) is configured to create a depression between the first discharge element (11) and the second discharge element (18), so as to conduct at least part of the gases (G, G') present in the cooking chamber (3) to the second discharge element (18);In particular, the apparatus (55) comprises a plurality of burners (1) arranged in series along a direction (DD), parallel to the transport path (P); in particular, with said burner (1) having a longitudinal axis (AA) transverse (in particular, perpendicular) to the transport path (P), for example, perpendicular to the said wall (56) of the industrial furnace (2). Petition 870230108212, dated 07 / 12 / 2023, p. 36 / 37 5 / 5; 17. APPARATUS (55), according to claims 15 or 16, characterized by comprising at least one electronic control unit, configured to control the burner (1) so as to alternate cyclically from a flame cooking configuration to a flameless cooking configuration; in particular, with the electronic control unit being configured to cyclically extinguish the flame by decreasing the fuel supply, and, if necessary, the oxidant supply, and to restore the fuel supply, and, if necessary, the oxidant supply, thus allowing the burner to operate in flameless mode, including re-igniting the flame to return to the flame cooking configuration.

18. METHOD FOR FIRING CERAMIC ARTICLES (T), transported within a tunnel kiln, characterized by comprising the steps of: - feeding a burner, in particular as described in any one of claims 1 to 14, with a fuel comprising at least a hydrogen percentage greater than 20%, in particular greater than 50%, more particularly greater than 70%; - simultaneously feeding said burner with an oxidizer and igniting a flame, at least partially, inside the burner and in a firing chamber of the tunnel kiln; - controlling said flame using a feedback control; in particular, with the method comprising cyclically, after the firing chamber of the kiln has reached a certain temperature, the additional steps of: - extinguishing the flame by decreasing the fuel feed, and in particular, the oxidizer feed;and - to restore the fuel supply and, in particular, the oxidant, thus generating, inside the tunnel kiln, a flameless combustion that fires the ceramic articles. Petition 870230108212, dated 07 / 12 / 2023, page 37 / 37;

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