The present disclosure relates to a burner and a furnace including this burner.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Burners are combustion devices intended to produce heat by combustion of a mixture of fuel (usually a gas) and an oxidizer (generally air).
There are different types of burners, such as atmospheric burners, forced air burners or premix burners.
Premix burners are burners where air is mixed with gas in a premix chamber, with or without the aid of a fan, before distribution on the surface of a porous support where the flame is developed.
It is known to produce this porous support by an assembly of metal fibers. The fibers are conventionally made from a fire-resistant alloy, for example Fecralloy®, configured to resist corrosion at temperatures above 1000° C.
These metallic fibers can be woven to obtain a flexible fabric capable of offering a wide variety of shapes. The metallic textile is traditionally mounted on a steel casing which contains distribution plates intended to ensure the homogeneity of the combustion.
Burners with porous support have many advantages relative to other burners, such as for example homogeneous combustion with a wide modulation range. These burners in fact allow thermal transfer, either by radiation (infrared) or by convection (blue flame), as well as an easy transition between these two thermal transfer modes. The burners with porous support also offer high thermal efficiency with low emission rates (CO, NOx), low pressure drop, low thermal inertia, safety against backfire, as well as resistance to mechanical or thermal shocks.
It is thus known to use burners with a porous support in various fields such as the drying or the surface treatment of paints or coatings, the heat treatment of technical textiles, or for the cooking of foods such as cookies, pancakes, breads, brioches, etc., in food furnaces.
Generally, burners with a porous support can extend up to a length in the range of 2 to 3 meters. However, in the case of food furnaces, where the burners are arranged perpendicular to a conveyor belt displacing the food to be cooked, the width of this conveyor belt can exceed 4 to 8 meters. There is therefore a need for large burners.
A drawback of large burners is their deformation under the effect of expansion. This deformation generates a pronounced deflection, also called the banana effect, which can alter the homogeneity of the cooking and the lifetime of the burner (e.g., tearing of the metal fabric).
Another drawback of large burners is their size and their mass. This increases transport costs and can complicate their installation inside baking furnaces.
Another drawback is the edge effect that can occur on the sides of the furnace. It is necessary to provide the same amount of energy over the entire width of the conveyor belt to cook food evenly. As the heat is lower on the sides of the furnace, taking into account the energy absorption by its side walls, there is a need for a large burner capable of overcome these edge effects.
The teachings of the present disclosure overcome all or part of these drawbacks by providing a burner allowing a reduction in the deflection, a reduction in the size to reduce transport costs and facilitate assembly, and a homogeneous heat transfer over its entire length.
This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.
The present disclosure relates to a burner including a porous support and a combustion tube along which is mounted the porous support, the combustion tube having one or more openings for allowing fuel to pass to the porous support, wherein the combustion tube is formed of a plurality of tubular modules assembled together and in that the burner further includes at least one distribution tube extending inside the combustion tube to distribute the fuel in a predetermined manner in the combustion tube.
Thus, the burner according to the disclosure, via its combustion tube formed by an assembly of modular sections, makes it possible to have a large burner while limiting the deflection and reducing the size and transport costs. The distribution tube allows a homogeneous distribution of the fuel within the combustion tube.
According to one form, the opening(s) of the combustion tube are slots orthogonal to a longitudinal axis of the burner.
This allows the fuel to pass more easily to the porous support.
Advantageously, the burner has a supply module including sparking means and one or more sparking orifices arranged under the sparking means and configured to allow more fuel to pass than a section of the same length of the combustion tube.
This makes it possible to send a surplus of fuel to the level of the sparking means in order to facilitate the sparking.
According to one form, the burner includes fixing means configured to fix in a sealed manner adjacent tubular modules.
According to one form, the fixing means include fixing flanges bearing against one another.
This bearing-plane contact, flange against flange, ensures an effective sealing between two modules. This also makes it possible to decrease the deflection.
According to one form, the fixing flanges support the at least one distribution tube inside the combustion tube.
According to one form, the fixing means include calibrated leakage means allowing fuel to pass to the porous support at the junction of the adjacent tubular modules.
This ensures the continuity of the flame at the junction of two modules. These calibrated leakage means can be formed by a notched portion of the fixing flanges.
According to one form, the burner includes a single distribution tube.
According to one form, the distribution tube includes one or more distribution orifices arranged opposite the porous support.
This feature makes it possible to create a pressure drop aimed at better distributing the fuel within the combustion tube.
According to one form, the burner includes several distribution tubes, of which primary distribution tube intended to distribute the fuel in a first combustion zone formed by one or more tubular modules of the combustion tube, and at least one secondary distribution tube configured to distribute the fuel in a predetermined manner in a downstream combustion zone with respect to the first combustion zone and formed by one or more other tubular modules of the combustion tube.
This allows the independent management of several combustion zones.
Advantageously, the at least one secondary distribution tube includes a blind part extending at least through the first combustion zone.
According to one form, the primary distribution tube and the at least one secondary distribution tube have an openwork part having an upstream portion having a larger perforation zone than a downstream portion.
This feature makes it possible to ensure the continuity of the flame. It prevents a dark zone from appearing at the start of the openwork part due to the fuel propagation speed.
By larger perforation zone on an upstream portion compared to a downstream portion of the openwork part of the distribution tube, it is meant that the total openwork zone is greater than that of a portion of the same length located downstream with respect to this one. Thus, more fuel escapes through this upstream portion than through a downstream portion of the same length.
It will be noted that upstream and downstream are here defined with respect to the overall direction of circulation of the fuel inside the burner.
According to one form, the primary distribution tube and the at least one secondary distribution tube have an openwork part including distribution orifices arranged facing the porous support.
This feature allows better fuel distribution. The flow of fuel is not hampered by the presence of the other distribution tube(s).
According to one form, the primary distribution tube and the at least one secondary distribution tube have an end portion including an axial plug and a radial outlet opening.
This allows slowing down the arrival of fuel at the end of the combustion tube zone and creates a pressure drop aiming at better distributing the fuel within the combustion tube.
Advantageously, the radial outlet is arranged opposite the porous support.
According to one form, the terminal portion is arranged at a distance from a downstream end of the corresponding combustion zone, and in one optional form is at an upstream end of the last of the tubular modules forming the corresponding combustion zone.
This feature allows a homogeneous distribution of the fuel in the corresponding zone of the combustion tube while avoiding a surplus of fuel in the last tubular module of this zone.
Advantageously, the openwork part of each distribution tube extends along only part of the corresponding zone of the combustion tube. In particular, each zone of the combustion tube is formed of several consecutive tubular modules, and the end portion extends into the last tubular module of the corresponding zone, near the upstream end of this tubular module, the end portion being, in one optional form, closer to the upstream end than to the downstream end of the last tubular module of the corresponding zone.
According to one form, the burner includes adjustment means configured to independently adjust the flow rate of fuel entering each distribution tube.
According to another form, the teachings of the present disclosure provide for a furnace including a burner having one or more of the aforementioned features.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
The burner 1 includes a combustion tube 2 formed of several tubular modules 20, a distribution tube 4 arranged inside the combustion tube 2, and a porous support 6 supported by the combustion tube 2 and on the surface of which is intended to burn a pre-mixture of air and gas. The burner 1 is advantageously a burner 1 with premixing and surface combustion.
The porous support 6 is a fuel permeable support, for example a premix of gas and air. The porous support 6 advantageously includes metallic fibers, which can be woven so that the porous support 6 forms a flexible metallic fabric. These metal fibers are made of a fire-resistant alloy configured to resist corrosion at temperatures above 1000° C., such as, for example, Fecralloy®.
The porous support 6 selectively allows using a heat transfer mode by radiation (infrared) or by convection (blue flame), and offers an easy transition between these two modes. By radiation heat transfer mode (infrared) is meant a thermal transfer with a power density in the range of 100 to 500 kW·m−2. By a thermal transfer mode by convection (blue flame) is meant a thermal transfer with a power density in the range of 500 to 10,000 kW·m−2.
The combustion tube 2 extends longitudinally along the axis A and supports the porous support 6. The porous support 6 can be fixed on the combustion tube 2 by spot welding (fusion of the fabric forming the porous support 6 with the combustion tube 2). The porous support 6 therefore also extends longitudinally along the axis A, in particular, over the entire length of the combustion tube 2.
The combustion tube 2 is hollow, advantageously cylindrical. The combustion tube 2 has an upstream end, connected and closed by a supply module 8, and a downstream end, connected and closed by a closure module 10.
The combustion tube 2 is perforated. As represented in
The combustion tube 2 includes a plurality of tubular modules 20 aligned and connected one after the other so as to form the combustion tube 2. Each tubular module 20 therefore constitutes a section of the combustion tube. Thus, as visible in
The tubular modules 20 are advantageously similar. In particular, they can be of equal length. According to the example of
The tubular modules 20 are fixed end to end to each other to form the combustion tube. To this end, as can be seen in
The fixing flanges 24 can be arranged at the ends of the tubular modules 20. Thus, each tubular module 20 includes a first fixing flange 24, at an upstream end 20a of the tubular module 20, and a second fixing flange 24, at a downstream end. The first flange 24 of fixing a tubular module 20 is intended to be fixed to the second flange 24 of fixing a previous tubular module 20.
The flanges 24, possibly in the form of a plate, have a collar projecting radially from the lateral wall of the tubular modules 20 and therefore from the combustion tube. The flanges 24 are for example orthogonal to the longitudinal axis A. The fixing flanges 24 have an advantageously flat fixing face 240, intended to receive the fixing face of another fixing flange 24.
In one optional form, the fixing flanges 24 do not extend all around the combustion tube. They can have a primary notch 242 allowing passage of the porous support 6 at the junction of two adjacent tubular modules 20. As illustrated in
Advantageously, the fixing flanges 24 do not only extend outside the combustion tube 2 by forming a collar, but also inside the combustion tube 2, forming a partition wall 246 preventing the passage of the fuel located in the combustion tube 2 from one tubular module 20 to the other (except via the calibrated leakage means), as illustrated in
The fixing flanges 24 may have one or more axial through openings 248 allowing the passage of a distribution tube 4. In one optional form, each through opening 248 has a shape complementary to that of the distribution tube 4 that it receives. The through opening(s) 248 extend through the partition wall 246 to allow the distribution tube(s) to pass through the junction of two adjacent tubular modules 20. According to the example of
The fixing flanges 24 thus close the ends of the tubular modules 20, except to achieve the calibrated leakage or to allow the passage of the distribution tube(s) 4 from one module 20 to another. The fixing flanges 24 also make it possible to support the distribution tube(s) 4 which extend inside the combustion tube 2. This or these distribution tubes 4 in fact rest on the inner edge delimiting the corresponding through opening 248.
The distribution tube(s) 4 are intended to distribute the fuel in a predetermined manner within the combustion tube 2. Each distribution tube 4 extends inside the combustion tube, along the longitudinal axis A, and includes (see for example
Unlike the combustion tube 2, the distribution tube(s) 4 are advantageously not designed in a modular fashion and can extend in a single piece from their upstream end where the inlet orifice is located up to their downstream end. The distribution tube(s) 4 have a smaller diameter than the combustion tube 2 to allow the fuel to circulate about the distribution tube(s) 4, that is to say in the combustion tube 2, once the fuel has left the distribution tube 4.
As described above, each distribution tube 4 can be supported and held in place inside the combustion tube 2 by means of the fixing flanges 24.
Each distribution tube 4 includes an openwork part 42, including one or more distribution orifices 420 (see
With reference to
With reference to
In particular, these distribution tubes 4 include a primary distribution 4, which is intended to distribute the fuel in the combustion zone A most upstream of the combustion tube 2, and one or more (e.g., two according to the example of
For example, as illustrated in
The primary and secondary distribution tubes 4 all include an openwork part 42 having distribution orifices 420 intended to allow the passage of the fuel from the inside of the primary or secondary distribution tube 4, into the corresponding zone of the combustion tube 2. In one optional form, these distribution orifices 420 are arranged facing the porous support 6. In one optional form, the openwork part 42 extends from the first to the penultimate of the tubular modules 20 forming the concerned combustion zone.
Referring to
Referring to
The end portion 44 extends into the last of the tubular modules 20 forming the combustion zone served by the corresponding distribution tube 4. In one optional form, this terminal part 44 is arranged at the level of the upstream end 20a of this tubular module 20, or in any case at a distance from the downstream end 20b, advantageously closer to the upstream end 20a than to the downstream end 20b. The end portion 44 extends over a length substantially shorter than that of the openwork part 42. For example, the length of the distribution tube 4 in the last tubular module 20 of the served combustion zone is less than a fifth, and in one optional form is less than a tenth of the length of this tubular module 20.
The secondary distribution tubes 4 further include a blind portion 46 which is located upstream of their openwork part 42. This blind portion 46, in the form of a tube without perforations on its lateral wall, is intended to extend through the combustion zone(s) located upstream of that served by the openwork part 42 of the same distribution tube 4.
Referring to
With reference to
With reference to
As indicated previously, the burner 1 includes a supply module 8 connected upstream of the combustion tube 2 to supply each distribution tube 4 with fuel. The supply module 8, as well as the closure module 10 where appropriate, can be connected to the first, respectively to the last, of the tubular modules 20 forming the combustion tube 2 by means of the fixing means described above, like the fixing brackets 24. The supply module 8 allows the fuel supply of the distribution tube(s) 4.
The burner 1 advantageously includes means for adjusting the flow rate of fuel entering the distribution tube 4, or into each distribution tube 4. When there are several distribution tubes 4, the adjustment means allow the fuel flow rate to be adjusted for each distribution tube 4 independently of each other. As illustrated in
With reference to
The disclosure also concerns a furnace the burner 1 such as previously described. In particular, this furnace can be a food furnace intended for cooking foods.
The disclosure is in no way limited to the specific forms described above, these forms have been given only by way of example. Those of skill in the art will appreciate that modifications to the examples can be done, in particular from the point of view of the constitution of the various devices or by the substitution of technical equivalents, without thereby departing from the scope of protection of the disclosure.
Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word “about” or “approximately” in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.
As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”
The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.
Number | Date | Country | Kind |
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1907813 | Jul 2019 | FR | national |
This application is a continuation of International Application No. PCT/FR2020/051250, filed on Jul. 10, 2020, which claims priority to and the benefit of FR 19/07813 filed on Jul. 11, 2019. The disclosures of the above applications are incorporated herein by reference.
Number | Date | Country | |
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Parent | PCT/FR2020/051250 | Jul 2020 | US |
Child | 17573223 | US |