EP4215814A1 - Brenner - Google Patents

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Publication number
EP4215814A1
EP4215814A1 EP22216528.4A EP22216528A EP4215814A1 EP 4215814 A1 EP4215814 A1 EP 4215814A1 EP 22216528 A EP22216528 A EP 22216528A EP 4215814 A1 EP4215814 A1 EP 4215814A1
Authority
EP
European Patent Office
Prior art keywords
diffuser
burner
sheet metal
framework
separation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP22216528.4A
Other languages
English (en)
French (fr)
Inventor
Massimo Gilioli
Alberto FARA
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Beckett Thermal Solutions SRL
Original Assignee
Beckett Thermal Solutions SRL
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Beckett Thermal Solutions SRL filed Critical Beckett Thermal Solutions SRL
Publication of EP4215814A1 publication Critical patent/EP4215814A1/de
Withdrawn legal-status Critical Current

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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
    • F23D14/02—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone
    • F23D14/04—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone induction type, e.g. Bunsen burner
    • F23D14/10—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone induction type, e.g. Bunsen burner with elongated tubular burner head
    • 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
    • F23D2203/1017—Flame diffusing means characterised by surface shape curved
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2203/00—Gaseous fuel burners
    • F23D2203/10—Flame diffusing means
    • F23D2203/102—Flame diffusing means using perforated plates
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2203/00—Gaseous fuel burners
    • F23D2203/10—Flame diffusing means
    • F23D2203/106—Assemblies of different layers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2900/00—Special features of, or arrangements for burners using fluid fuels or solid fuels suspended in a carrier gas
    • F23D2900/14—Special features of gas burners
    • F23D2900/14001—Sealing or support of burner plate borders

Definitions

  • the present invention relates to a burner for a combustion unit, e.g., for gas boilers.
  • Prior-art combustion units comprise a combustion chamber with a heat exchanger, a burner connected to the combustion chamber for generating heat through the combustion of a mixture of combustible gas and combustion air in the combustion chamber, and a supply conduit for supplying the gas and air mixture to the burner.
  • the known burner comprises:
  • the combustion surface and the framework are made of a single piece of sheet metal which is resistant to high temperatures, perforated at the combustion surface, and impermeable at the framework.
  • This solution is disadvantageous due to the formation of breaks caused by high temperature gradients between very hot zones and relatively cold zones.
  • a flexible porous layer on the perforated sheet metal for example a fabric or a metal fiber mesh which acts both as a combustion surface and flame spacer which spaces the combustion zone apart from the perforated sheet metal, and insulating material which shields the sheet metal from the high temperatures of the gases present in the combustion chamber, at the cost of needing to provide for and assemble an additional expensive component.
  • sheet metal diffusers are subject to buckling (uncontrolled deformations of instability from a modal form to another modal form of the diffuser) due to the high rigidity of the sheet metal in the plane thereof and the impossibility to fully extend freely according to the thermal stresses. This results in uncontrolled mechanical stresses combined with thermal stresses which increase the risk of premature breakage of the diffuser.
  • Mesh diffusers are easily deformable both in the extension plane and outside the extension plane and do not have the aforesaid buckling problem.
  • metal meshes for burners are very expensive, the porosity thereof is subject to statistical variations which cannot be controlled with certainty, and the manufacturing of burners with diffusers made of metal mesh is more complex, slower and expensive than the manufacturing of burners with diffusers made of perforated sheet metal.
  • EP3412967A1 describes a burner with:
  • This known burner achieves within certain limits an uncoupling of the thermal deformations of the individual segments formed by the diffuser and reduces the onset of buckling due to thermal expansion.
  • one or both of the ends of the partial separation slits of the diffuser forms/form relaxation grooves or holes, which are rounded and enlarged as compared to the width of the partial separation slit.
  • a gas burner for example a premixed gas burner, for example suitable for gases and gas mixtures having high combustion speed, e.g., hydrogen gas and mixtures thereof, comprises:
  • the construction of the diffuser with a plurality of diffuser segments completely separated from one another, but only connected indirectly by further components of the burner not belonging to the same sheet metal thereof, further improves the uncoupling of the thermal deformations of the individual segments, the thermal resistance, the resistance against the onset of fatigue fractures, and obviates the onset of thermal expansion buckling, also in the presence of higher temperature gradients.
  • the complete separation of the individual diffuser segments and their juxtaposition side-by-side at a freely definable and lockable distance further allows creating, in an easy, inexpensive and industrially repeatable manner, a much narrower gap than a minimum cutting width obtainable using traditional sheet metal cutting technologies.
  • the juxtaposition of diffuser segments completely separated from one other allows creating freely definable and not necessarily uniform slit profiles in an easy and inexpensive manner, while remaining within a very small slit width range. This possibility to create very narrow separation slits reduces per se the risk of light back even when the burner is supplied with gas, e.g., hydrogen, having high combustion speed.
  • the covering of the separation slits with the covering strips further extends the gas path through the diffuser at the separation slits and reduces the overall passage section and thus the local porosity. This further reduces the risk of light back.
  • the covering strips stabilize the position of the free edges of the diffuser segments, thus obviating undesired, unplanned thermal or mechanical deformations. This leads to a synergetic anti-light back and thermal resistance effect.
  • the figures show a gas burner 1 suitable for a combustion unit of the type having a first housing part (combustion housing) which internally delimits a combustion space, a second housing part (gas supply housing) which internally delimits a gas supply space, and indeed the burner 1 connected between the first housing part and the second housing part.
  • the burner 1 comprises:
  • the combustion surface 5 faces an outer side 8 of the burner 1 (the outer side 8 defines the combustion space 8 of the combustion chamber 9) so that a gas mixture 10 conveyed through the diffuser 4 can be combusted in the form of a flame pattern on the combustion surface 5.
  • the diffuser 4 is formed by a plurality of diffuser segments 11 made of perforated sheet metal not belonging to the same piece of sheet metal and completely separated from one another by means of separation slits 12 and placed side-by-side along the separation slits 12, and wherein the separation slits 12 extend in the transverse direction 7 over the entire transverse extension of the diffuser 4.
  • each covering strip 14 extends along respectively one of the separation slits 12 overlapping and at least partially in contact with both the free edges 15 of the two diffuser segments 11 which are bordering and delimiting the separation slit 12, so as to cover each of said separation slits 12.
  • the diffuser segments 11 are preferably not connected directly to one another, but individually with the framework 2.
  • the combustion surface 5 or the entire diffuser 4 can be substantially flat and the separation slits 12 can be substantially straight and, possibly, parallel to one another.
  • the part of the diffuser forming the combustion surface 5 can be in the shape of a shell rounded towards the combustion side 16, advantageously a half-cylinder or a portion of cylinder, preferably with a constant cross section (in a transverse plane orthogonal to the longitudinal direction 6) with the exception of local interruptions due to the separation slits 12 and perforation.
  • the separation slits 12 are advantageously straight in the top view and shaped like an arc of a circle in the cross-section view, as shown in figures 1 , 3 , 8 , 11 , 12 .
  • the separation slits 12 are advantageously parallel to one another.
  • the separation slits 12 have a maximum width 16 in the longitudinal direction 6 of less than 1 mm ( figure 13 ).
  • the separation slits 12 have a gradually converging shape from a central region 17 (about half the central length or a third of the central length of the separation slit 12) towards the two opposite ends 18 ( figure 13 ).
  • the separation slits 12 form zero-thickness contact sections or points 19 where the free edges 15 of the bordering diffuser segments 11 abut in contact with one another. This allows a certain relative positioning between consecutive diffuser segments 11, without any need to measure distances or adjust the position of the diffuser segments 11 during the assembly of the burner 1.
  • the contact sections 19 are positioned at opposite ends 18 of the separation slits 12.
  • the diffuser 4 or the diffuser segments 11 are formed from (obviously heat resistant) sheet steel having a thickness of the individual sheet metal in the range from 0.3 mm to 3 mm, preferably from 0.5 mm to 1.5 mm, for example 0.9 mm.
  • the diffuser 4 or the diffuser segments 11 are stacked steel sheet metal multi-layer structures, wherein the thickness of the individual sheets (individual layers) is preferably within the thickness values and ranges described above for the individual sheet.
  • the perforation 20 of the diffuser 4 does not extend as far as the separation slits 12.
  • the separation slits 12 are delimited by the free edges 15 of the diffuser segments 11 preferably smooth or with a continuous shape to obviate the onset of notching effects and the formation of cracks.
  • the diffuser segments 11 advantageously have a substantially constant and/or substantially equal length 22 in the longitudinal direction 6, to facilitate manufacturing, storage and assembly and for the purpose of ensuring that properties of thermal capacity, temperature distribution, and thermal and mechanical stresses, as well as the distribution of gas mixture permeability are as uniform as possible, and thus to obtain burner operating properties which are as uniform, certain and predictable as possible.
  • the diffuser segments 11 advantageously have a length 22 in the longitudinal direction 6 which is less than a width 23 thereof in the transverse direction 7.
  • the thermal expansions of the individual diffuser segments 11 in the longitudinal direction 6 cannot be added together due to the separation slits 12, and the thermal expansions of the individual diffuser segments 11 in the transverse direction 7 can be absorbed thanks to an out-of-plane bulging of the framework 2.
  • Such a bulging will systematically take place in the direction of the combustion space (outer side 8 of the burner 1) due to the thermal bending of the diffuser 4 towards the hotter side thereof.
  • the diffuser segments 11 consist of or are formed by a plate bent in an arc shape, where opposite ends 27 of the plate form two arc bases and are bent towards the outside and, preferably, oriented in a common plane parallel to a plane of the framework 2.
  • the opposite ends 27 of the plate form connection ends 27 for connecting the diffuser segment 11 to the framework 2.
  • the diffuser 4 is a planar diffuser
  • the diffuser segments 11 consist of or are formed by an elongated planar plate, wherein opposite ends of the plate are oriented in a common plane parallel to the plane of the framework 2 and form connection ends 27 of the diffuser segment 11 to the framework 2.
  • the diffuser 4 is tubular, e.g., cylindrical or frustoconical, the diffuser segments 11 consist of or are formed by an elongated plate bent in a closed loop or a continuous tubular wall, and connected by a small connection frame or one or more appendices of the framework 2 of the burner.
  • the burner 1 comprises two closing portions 24 made of sheet metal which extend outside the plane of the framework 2 and close longitudinal end zones 25 between the combustion surface 5 and the framework 2.
  • the two closing portions 24 are made of unperforated sheet metal.
  • the closing portions 24 can be shaped (e.g., by a press) as a part (e.g., a quarter) of a spherical cap for creating a gradual transition between the plane of the framework 2 and an apical region of the combustion surface 5.
  • the closing portions 24 can be shaped like flat portions with or without stiffening ribs.
  • closing portions 24 are particularly advantageous to form at least one or both of the closing portions 24 together with the framework 2 using a single piece of sheet metal, e.g. by forming or bending the closing portions 24 outside the plane of the framework 2 along transverse edges 21 of a front opening 22 of the framework 2 ( figures 3, 4 ).
  • the perforation or piercing of the diffuser 4 can comprise, by way of advantageous but non-limiting example, holes having diameters in the range from 0.2 mm to 0.7 mm and/or slots with lengths in the range from 5 mm to 50 mm and width less than 0.5 mm.
  • the covering strips 14 can be separate pieces of sheet metal connected individually to the framework 2, or the covering strips 14 are portions of a covering framework 28 formed by a single piece of sheet metal ( figures 3, 4 , 9 , 10 ).
  • the covering strips 14 are made of continuous sheet metal, without perforation, in order to really ensure a deviation of the gas flow at the separation slits 12 and to facilitate manufacturing and reduce the manufacturing cost of the burner 1.
  • the covering strips 14 form:
  • the covering framework 28 forms an outer frame 33, consisting for example of two opposite sheet metal strips, which supports and positions the covering stripes 14.
  • the outer frame 33 lies in a plane parallel to the plane of the framework 2.
  • the outer frame 33 forms one or more local stiffening ribs 34, e.g., a plurality of bosses equidistant from one another ( figures 4 , 7 ).
  • the covering strips 14 are formed from sheet steel having a thickness of the individual sheet metal in the range from 0.3 mm to 1.5 mm, preferably from 0.5 mm to 1.0 mm, for example of 1 mm.
  • the framework 2 is formed by a flat metal sheet, preferably substantially elongated and rectangular, which delimits a passage opening 35 at which the diffuser 4 is arranged.
  • the framework 2 can be made of sheet steel having a thickness of the individual sheet metal in the range from 0.5 mm to 2 mm, preferably from 0.8 mm to 1.5 mm, for example of 1 mm.
  • the burner 1 can comprise a distributor 36, preferably made of perforated sheet metal with larger openings than the perforation openings of the diffuser 4.
  • the distributor 36 is placed on the side of the diffuser 4 opposite to the combustion side and can have a similar shape to that of the combustion surface 5, e.g., a planar or convex shape or a portion of a cylinder, or half-cylinder, or a tubular, e.g., cylindrical or frustoconical shape.
  • the covering strips 14 can be formed by unperforated portions of sheet metal of the distributor 36 which protrude with respect to perforated portions 37 of the distributor 36 towards the outside of the burner 1 and which rest in contact against the diffuser segments 11 ( figures 14, 15 ).
  • the perforated portions 37 of the distributor 36 are instead spaced apart from the diffuser 4 so as to be able to correctly perform the task of distributing the gas mixture towards the diffuser 4.
  • the diffuser 36 can be made from the covering framework 28.
  • the diffuser 4 is sandwiched and held between the framework 2 and the covering framework 28.
  • the outer strip portions 29 of the diffuser segments 11 are sandwiched between an edge of the framework 2 and the outer frame 33 of the covering framework 28.
  • the framework 2 and the covering framework 28 can be connected to each other by welding spots or by mechanical fixing without welding, e.g., Tox clinching, in a plurality of discrete connection positions, spaced apart from one another.
  • the diffuser segments 11 can be fixed into the burner 1 only by friction interlocking or clamping or welding or Tox clinching.
  • the direct fixing between the framework 2 and the covering framework 28 may not involve the diffuser segments 11, allowing the diffuser 4 and the individual segments thereof to have greater freedom of deformation and movement to accommodate thermal expansions.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Gas Burners (AREA)
EP22216528.4A 2022-01-25 2022-12-23 Brenner Withdrawn EP4215814A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT202200001178 2022-01-25

Publications (1)

Publication Number Publication Date
EP4215814A1 true EP4215814A1 (de) 2023-07-26

Family

ID=81325819

Family Applications (1)

Application Number Title Priority Date Filing Date
EP22216528.4A Withdrawn EP4215814A1 (de) 2022-01-25 2022-12-23 Brenner

Country Status (1)

Country Link
EP (1) EP4215814A1 (de)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL8801383A (nl) * 1988-05-30 1989-12-18 Nefit Nv Metalen branderdek.
EP3412967A1 (de) 2017-06-07 2018-12-12 Worgas Bruciatori S.R.L. Brenner

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL8801383A (nl) * 1988-05-30 1989-12-18 Nefit Nv Metalen branderdek.
EP3412967A1 (de) 2017-06-07 2018-12-12 Worgas Bruciatori S.R.L. Brenner

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