Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
  • F23D14/46—Details, e.g. noise reduction means
  • F23D14/48—Nozzles
  • F23D14/58—Nozzles characterised by the shape or arrangement of the outlet or outlets from the nozzle, e.g. of annular configuration
  • F23D14/583—Nozzles characterised by the shape or arrangement of the outlet or outlets from the nozzle, e.g. of annular configuration of elongated shape, e.g. slits
  • F23D14/586—Nozzles characterised by the shape or arrangement of the outlet or outlets from the nozzle, e.g. of annular configuration of elongated shape, e.g. slits formed by a set of sheets, strips, ribbons or the like
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
  • F23D14/46—Details, e.g. noise reduction means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D2203/00—Gaseous fuel burners
  • F23D2203/10—Flame diffusing means
  • F23D2203/101—Flame diffusing means characterised by surface shape
  • F23D2203/1012—Flame diffusing means characterised by surface shape tubular
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D2211/00—Thermal dilatation prevention or compensation

Definitions

• the present invention relates to a method of manufacturing a gas burner element. It also relates to a burner element and a burner in use.
• Fibers which may be made of ceramic or metallic materials, or else of rigid, perforated, metallic or ceramic plates, allowing combustion distributed over a large area with a homogeneous and therefore lower flame temperature. than that obtained by other burner techniques.
• combustion - which is a chemical reaction of oxidation of a reducing reagent (gas) by an oxidizing reagent (air) - are complex and varied.
• the "combustion site" is in fact at the same time the seat of reaction, formation and reduction of the oxides which have just been born.
• document FR-A-1 037 897 discloses several embodiments of a gas burner.
• the burner is formed from several parallel and contiguous metal strips which carry channels on only one of their large faces. The air + gas mixture flows through these channels.
• the flame obtained with this type of burner is not uniform and tends to "drop" from the surface of the burner. In other words, it is not stable.
• the present invention aims in particular to propose a method of manufacturing a gas burner element making it possible to obtain a very good quality of combustion of the gas-air mixture, that is to say rejecting the least possible polluting gases, while being of an economic implementation.
• This process comprises, in a manner known by FR-A-1 037 897, the steps according to which: a) at least one metal strip whose width corresponds to the thickness of the burner element to be obtained is subjected to an operation aimed at forming in one of its large faces a series of grooves opening onto its banks, the other large face of the strip being kept smooth; b) several sections of this metal strip, or several metal strips, are juxtaposed in order to apply them one against the other in such a way that their flat face is in contact with the grooved face of the section or of the adjacent strip, and vice versa; c) assembling all of the sections of strips or strips thus juxtaposed (s) to obtain a rigid element.
• openings have an elongated rectangular shape and are arranged in the longitudinal direction of the strip;
• the mat ⁇ asting operation is carried out using rotary forming tools, such as a ribbed wheel and a counter-roller.
• rotary forming tools such as a ribbed wheel and a counter-roller.
• the grooves are made transversely on the strip;
• step b sections or bands are used whose grooves are directed differently and / or whose sections are different;
• step a an alumina or pure chromium powder is sprayed onto the strip, this projection taking place hot or cold, and in that, following step c), it is subjected said element being heated so as to cause said powder to melt.
• the invention also relates to a gas burner element.
• This burner element of the type formed by a juxtaposition of sections of strips or strips applied against each other, each section or strip having on one of its large faces a series of grooves opening onto its banks, the other large face being smooth, the juxtaposition being such that their flat face is in contact with the grooved face of the section or of the adjacent strip, is characterized by the fact that the edges of the strips or sections have bosses located in the extension of said grooves.
• the juxtaposition consists of a winding of one or more metal strips on it (s) -same (s), the winding axis being perpendicular to the large faces of said (said) strip (s).
• the element has several weld lines on its external or internal surface, these lines being equidistant - or substantially equidistant - angularly from one another and arranged along the generatrices of the winding.
• the invention also relates to a gas burner which includes such an element.
• said element is mounted between two flanges, each being equipped with a flexible refractory seal for the reception of the ends of the element, so that the latter can diate freely, while being held between the flanges.
• the flexible joint is formed of ceramic fibers.
• the total thickness of the strip which constitutes the burner may have a different structure depending on whether a blue flame or a radiant combustion is desired.
• the grooves which cross the strip are, in a cases, laminar. In the other, they pass through a "labyrinth structure" which causes a considerable drop in thermal conductivity between the face exposed to combustion and the opposite face, exposed to cold gases.
• FIG. 1 is a schematic view illustrating the implementation of the first step of the method of the invention
• FIG. 2A and 2B are respectively top and side views of a strip after the implementation of the first step of the method;
• FIG. 3 is a schematic view illustrating an optional punching step, which can be implemented prior to the first step illustrated in Figure 1;
• FIG. 6 is a schematic top view of a strip obtained according to the method illustrated in Figure 5;
• FIG. 7 is a schematic side view of a stack of metal strips according to that shown in Figures 2A and 2B;
• FIG. 8 is a view of the stack of Figure 6, cut transversely by the broken plane VIII-VIII of Figure 7;
• Figure 9 is a view similar to Figure 8, but showing a stack of strips of the same type, subjected prior ⁇ ment punching;
• FIG. 10 is a schematic top view of a burner comprising an element according to the present invention.
• FIG. 1 1 is a schematic view of the means for implementing a second method of manufacturing the burner element
• FIG. 12 schematically shows the implementation of a third method of manufacturing a burner element
• FIG. 13 is a partial perspective view of an element obtained in accordance with the manufacturing method of Figure 1 2;
• - Figure 14 is a perspective view of the element of Figure 1 3, on which were made weld lines;
• FIG. 1 5 partially shows, in vertical section of a burner comprising an element according to Figure 1;
• - Figure 1 6 is a top view, in cross section of the burner of Figure 15, along the section plane XVI-XVI;
• FIG. 17 is an enlarged view of part of Figure 15;
• Figure 18 is a partial view similar to that of Figure 16, but on a larger scale;
• FIG. 19 is a detailed view of the means used for stacking several elements on top of each other;
• FIG. 20 is a perspective view of another embodiment of the burner;
• FIG. 21 is a detailed view of part of the burner in FIG. 20.
• This step is implemented by means of a rotary wheel 2, a counter-roller 2 'and guide rollers G and G'.
• the strip 1 has a width of 6 mm and a thickness of 0.5 mm. This width corresponds to the thickness of the burner element that one wishes to obtain.
• rollers G and G ' are rotary and guide the metal strip 1 in the direction i in the direction of the wheel 2 and of the counter-roller 2'.
• Appropriate means ensure the continuous and rotary drive of the latter. They have not been represented in order not to unnecessarily overload the figure.
• the wheel 2 whose direction of rotation has been symbolized by the arrow g, is a cylindrical metal roller which has reliefs (teeth) 20 and 21 at its periphery.
• these reliefs have been dimensionally exaggerated to allow a better understanding of the way in which the process step is implemented.
• the wheel has two alternating series of reliefs of different height which extend transversely over its entire periphery.
• the reliefs consist of parallel ribs, with a rounded free edge (semi-cylindrical).
• the strip 1 is guided in the direction of the arrow _f_ between the rollers G and G 'then forced between the wheel and the counter roller 2', the latter being rotated in the direction of the arrow h_ .
• a cold stamping of the strip is thus carried out, during which the material located in line with the reliefs is compressed and crushed in its thickness, so that the excess material is forced to creep laterally, towards the edges of the strip.
• the strip 1 has on its large upper face 1 1 a series of channels or transverse grooves 4 and 4 'whose shape is substantially complementary to that of the ribs 20 and 21. Its lower face is flat.
• FIGS. 2A and 2B show in detail the appearance of a portion of treated metal strip.
• the bottom of the grooves 4 and 4 ′ has a section in the shape of an arc of a circle.
• the diameter of the corresponding circles is respectively 0.25 and 0.15 mm.
• Other cross-sectional shapes can be provided, in particular rectangular.
• FIG 3 there is shown a strip portion 1 which has a series of grooves or transverse channels 50 all of the same section.
• the bosses formed at the two ends of the channels are also identical.
• the strip 1 shown in FIG. 4 comprises, for its part, a series of grooves 5 ′ arranged obliquely, that is to say slightly inclined relative to the transverse direction with, at each of their ends, a boss 50 '. It is of course possible to choose the orientation of the grooves that one wishes to obtain.
• the strip is subjected, before stamping, to a punching operation, using a tool 3 and a matrix 3 '.
• tools are intended to form a series of perforations in the strip.
• tool 3 has three punches
• the strip is then subjected to the stamping operation described with reference to FIG. 1.
• these perforations 12 and 1 3 are slots distributed along two lines parallel to the long sides of the strip and have the shape of elongated rectangles separated by a small amount of material.
• a strip can comprise for example four lines of perforations. The interest of these will be explained later.
• the second step of the method of the invention consists in juxtaposing and assembling several portions of strip so that these portions are in contact by their large faces.
• the grooved face 1 1 of a section being in contact with the face 10 of the adjacent section, it creates between the two strips a series of passages of different sections, opening on each bank.
• the sections 1 00 are assembled to obtain a rigid element. This operation can be performed for example by securing the ends of the sections to a fixing plate.
• FIG 10 schematically shows a top view of a gas burner which is equipped with an element according to the present invention.
• This burner 6 includes a base 60 of substantially parallelail-piped shape, the upper face of which is partially open. This opening (not visible) has dimensions adapted to receive, without significant play, a plate 1 03 formed of an assembly of portions of metal strips held together by end plates 61.
• a conduit 62 On one of the side faces of the base 60 is connected a conduit 62 for supplying air / gas mixture. This mixture is brought to the underside of the plate 103 and can flow freely through the latter through the grooves which it comprises.
• the second step of it consists in juxtaposing several grooved metal strips by winding them on themselves so as to obtain a disc-shaped plate.
• the strip portions having undergone the grooving and, optionally, punching operation are guided between rollers 20, 20 ', 70, 70' and 80, 80 '.
• the strips are then directed around a rotary mandrel 97 whose direction of rotation is identified by the arrow k.
• the winding is obtained in such a way that the winding axis 970 of the mandrel is parallel to the large faces of the strips.
• the winding obtained has the shape of a disc.
• the grooves formed in the strips are parallel to the axis of the disc.
• the strips 1, 1 ′, 1 ′′ may respectively have grooves such as those shown in FIGS. 2, 3 and 4.
• the strip 1 is bent and then wound around a rotary mandrel 98 of axis 99, so that the large faces of this strip are perpendicular to the axis 99.
• annular element 106 FIG. 13
• the grooves formed in the bands extend radially (that is to say perpendicular to the axis of the winding), or are slightly inclined relative to the radial direction if we are dealing with a stamping. "oblique" of the kind shown in Figure 4.
• the passages formed by these ribs connect to each other the inner and outer cylindrical wall surfaces of the winding.
• Such a burner element can be used for example in combination with a cylindrical heat exchanger, the burner being placed in its center.
• the manufacture of the element is finally completed by a mutual fixing of the turns of the winding, by welding.
• the element 106 shown in FIG. 14 has received several weld lines or beads 107 at its exterior or interior wall surface (not shown). These weld lines extend along generatrices of the cylindrical annular element 106 and are angularly equidistant from each other.
• the weld lines can be made using a stainless steel wire using a thumbwheel, using the so-called “Tig” technique (In English: Tungsten inert gaz) or "Mig", or at laser.
• the number of weld lines must be reasonable in relation to the diameter of the element. Thus, for example, eight weld lines are produced for an element having an outside diameter of 126 mm.
• the penetration of the weld material into the element should preferably remain low so as not to cause significant mechanical stresses. Thus, this penetration advantageously does not exceed one third of the width of the bands which constitute the element.
• Figures 1 5 to 18 is shown a gas burner equipped with an element 106 according to the description which has just been made.
• the element 106 of axis XX ', is interposed between two flanges 61', 60 '.
• the lower flange 61 ' is a thin disc; it has an edge 61 1 'raised at a right angle upward which externally delimits an annular groove 610'.
• a flexible annular seal 65' for example made of ceramic fibers having an "L" section whose wings are applied respectively against the edge 61 1 'and against the bottom of the groove 610' .
• the tie rods are fixed to the disc by any suitable means, for example by means of screws (not shown).
• the upper flange 60 ' has the shape of a thick crown. Its underside has an annular groove 600 'which receives a flexible seal 66' similar to the seal 65 'but of "U" section. It also includes a series of bores, not shown, for fitting, without significant play, the upper end of the tie rods 64 ′. This interlocking is completed by a fixing (for example by means of screws).
• the arrangement of the groove 600 ′ is such that when the flange 60 ′ is in place on the tie rods 64 ′, the seals 65 ′ and 66 ′ are plumb with each other. Between the flanges 60 'and 61' is mounted the element 106, the upper and lower end faces of which are in contact with the seals 65 'and 66', without there being excessive tightening of the element. between the joints.
• the number of tie rods 64 ′ is equal to the number of weld lines of the element 106 and the tie rods are made to correspond with the lines of the welds so that they are opposite one another.
• the burner also comprises two perforated cylindrical grids 62 'and 63' whose respective diameters are such that they are distributed on either side of the tie rods 64 '.
• the grid 63 'of smaller diameter is located inside the series of tie rods 64'.
• the grid 62 ′, of larger diameter, is external to the latter and has a series of projections 620 ′ constituted by “V” folds extending along generators and directed towards the outside, which bear against the internal wall of the element 106 and make it possible to maintain a constant spacing between the latter and the grid. On the inside, the projections keep the grid centered on the tie rods.
• Figure 19 is shown an annular profile, of section in the shape of "H", which allows to stack two elements 106 coaxially one on the other; the upper and lower grooves of this profile each receive a flexible seal 68 ′, respectively 69 ′, of "L” section, for example made of ceramic fibers.
• the burner 6 "of FIG. 20 is equipped with an element 108 formed by a juxtaposition of portions of slightly curved metal bands.
• Each band is formed by a sector of annular cylindrical burner element conforming to that of FIG. 14 , of large diameter
• the air / gas mixture A + G arrives at the level of the lower face of the plate formed by the assembly of the metal strips and flows from bottom to top through the channels 4 and 4 'of this plate. Because these channels have a small section and a long length, the body of the plate is relatively cold compared to the flame.
• the thickness of the assembly exposed to the flame, located above the perforations 12 and 13 does not allow a flashback to the labyrinths formed by the layers of perforations, thus avoiding interstitial combustion in these labyrinths, this which would lead to hot spots conducive to increasing pollution, especially Nox and CO.
• the labyrinth zone constitutes in the thickness of the burner a transition zone with low thermal conductivity, between the hot and radiant zone and the cold zone.
• the space between the perforations and the width of the latter define the dimensions of the points which alone transmit heat from one face 105 to the other 104.
• the width of the slots constitutes the number of these points.
• the temperature at face 104 is too high to resist adequately during tens of thousands of hours of operation, even when using refractory steels. This is why the strips can be subjected, after their stamping, to a hot spraying of alumina or pure chromium powder, a few microns thick, with an appropriate device. This spraying can also take place when cold, the powder then being mixed with a binder. After juxtaposition of the strips, the assembly is passed through the oven in a neutral atmosphere or under vacuum. This causes the powder to melt and diffuse into the metal that makes up the strips. The burner thus obtained is perfectly rigid, due to the contact points established by the molten powder, and can suitably withstand high temperatures.
• An air / gas mixture A + G is brought in from above the burner as shown in FIG. 15 and occupies the interior space delimited by the grid 63 '.
• the percentage of openings in this grid is chosen such that there is an overall expansion of the volume of air / gas mixture. In other words, a substantially uniform pressure is created over the entire height of the burner.
• the second grid 62 ′ ensures a good distribution of the flow of mixture A + G towards the burner element 106.
• the intermediate space between the two grids makes it possible to generate a second expansion.
• the element 106 tends to expand, both in length and according to its diameter. The phenomenon is not thwarted, because the element is interposed between two flexible seals. The burner element can therefore deform freely, the cohesion of the assembly being in any case ensured by the weld lines, the expansion of which follows that of the metal strips.
• the air / gas mixture radially crosses the passages between the turns of the winding 106, and the combustion takes place on the external surface of the burner element, the bosses lining said surface promoting the attachment of the flames, as has been explained. above with reference to the embodiment of FIG. 8.
• the operation of the burner in FIG. 20 is substantially the same as that described above.
• the grid 1 12 is used for the correct distribution of the mixture A + G.
• the latter which is curved like the burner element 108 itself, tends to deform (by thermal expansion) like the latter, further accentuating its curved.
• the channels conducive to the flow of the material are produced. mixture of air / gas but also the reliefs which allow the flame to hang on the upper surface of the burner.
• the element of the present invention makes it possible to obtain excellent combustions even at extreme air and gas flow rates.
• the CO emission is of the order of 6 to 10 ppm, so that the combustion hygiene is remarkable.
• the emission of Nox (nitrogen oxides) is 2 to 8 ppm, this in a range of power variation from 5 to 30 kW for a burner element of 126 mm in diameter and 120 mm in length.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Gas Burners (AREA)

Applications Claiming Priority (3)

Publications (2)

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ID=9443182

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• 1993
  • 1993-01-15 FR FR9300497A patent/FR2700604B1/fr not_active Expired - Fee Related
• 1994
  • 1994-01-14 WO PCT/FR1994/000046 patent/WO1994016269A1/fr active IP Right Grant
  • 1994-01-14 ES ES94904676T patent/ES2091691T3/es not_active Expired - Lifetime
  • 1994-01-14 EP EP94904676A patent/EP0679239B1/de not_active Expired - Lifetime
  • 1994-01-14 DE DE69400373T patent/DE69400373T2/de not_active Expired - Fee Related

Non-Patent Citations (1)

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