EP2876369A1 - Gas burner - Google Patents

Gas burner Download PDF

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Publication number
EP2876369A1
EP2876369A1 EP14194802.6A EP14194802A EP2876369A1 EP 2876369 A1 EP2876369 A1 EP 2876369A1 EP 14194802 A EP14194802 A EP 14194802A EP 2876369 A1 EP2876369 A1 EP 2876369A1
Authority
EP
European Patent Office
Prior art keywords
burner
combustion
combustion surface
membrane
zone
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Withdrawn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
EP14194802.6A
Other languages
German (de)
English (en)
French (fr)
Inventor
Antonio Acocella
Massimo Gilioli
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
Worgas Bruciatori 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 Worgas Bruciatori SRL filed Critical Worgas Bruciatori SRL
Publication of EP2876369A1 publication Critical patent/EP2876369A1/en
Withdrawn legal-status Critical Current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
    • F23D14/12—Radiant burners
    • F23D14/14—Radiant burners using screens or perforated plates
    • F23D14/145—Radiant burners using screens or perforated plates combustion being stabilised at a screen or a perforated plate
    • 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
    • F23D2203/1015—Flame diffusing means characterised by surface shape spherical
    • 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
    • F23D2203/103—Flame diffusing means using screens
    • 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
    • F23D2212/00—Burner material specifications
    • F23D2212/10—Burner material specifications ceramic
    • F23D2212/103—Fibres
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2212/00—Burner material specifications
    • F23D2212/20—Burner material specifications metallic
    • F23D2212/201—Fibres

Definitions

  • the present invention relates to a burner for a gas boiler.
  • Gas boilers of the prior art comprise a combustion chamber with a heat exchanger, a burner connected to or in the combustion chamber for the production of heat through the combustion of a mixture of fuel gas and combustion air inside the combustion chamber, a supply duct for supplying the mixture of gas and air to the burner, and a frame to support and connect the burner to the combustion chamber.
  • a distributor may also be provided for the purpose of distributing the mixture in a desired manner towards the diffuser wall.
  • the known distributors are usually made as walls with a plurality of through openings, for example, from perforated sheet, and can form an "internal" layer of the combustion membrane or, alternatively, a component spaced from the combustion membrane.
  • the heat produced by the combustion is conveyed by means of the hot combustion gases (convection) and by means of heat radiation to a heat exchanger for heating a fluid, for example water, which is subsequently conveyed to a utility, for example to a heating system of an industrial process, residential use or the like and/or of domestic hot water.
  • the flow rate of the fuel mixture affects the flame temperature, the temperature of the combustion membrane, the total heat capacity, flame stability, but, unfortunately, also the occurrence of undesirable phenomena of instability and detachment of the flame from the combustion surface.
  • the flame stability also depends on the local temperature of the combustion membrane which is in turn influenced by the geometry and the mass distribution in the combustion membrane and in the support frame. This is why the combustion membranes are often made of metal mesh which facilitates a three-dimensional double curvature contouring.
  • An example of a three-dimensional wire mesh burner is for example known from WO2012/095759A2 .
  • the perforated plate can be easily bent around a single axis
  • a shape with curving around multiple axes involves a stretching in the plane of the sheet with uncontrollable, unrepeatable deformations of the holes and with possible rupture of the sheet "bridges" between the adjacent holes.
  • metal fibre meshes (already in themselves expensive) are not dimensionally stable and are therefore often used in combination with a metal mesh support which further increases the cost of the burner.
  • properties (permeability, thickness, density) of the metal fibre meshes have a statistical distribution with high standard deviation. This makes it difficult to control the parameters that influence the combustion and involves uncertainties of ignition, flame detection, the load on the fuel flow and on the specific thermal power of the burner.
  • the purpose of the present invention is therefore to provide a burner with characteristics such as to overcome at least some of the drawbacks of the prior art.
  • a particular object of the invention is to better reconcile the needs of improved control of the combustion parameters and of manufacturing of the combustion membrane at low costs.
  • a gas burner for a boiler comprising a combustion membrane with a diffuser layer in the shape of a three-dimensional shell forming an outer combustion surface with at least one double-curvature region characterised in that the combustion surface comprises a first portion formed by a perforated metal sheet, and a second portion formed by a permeable fibre- or thread-based material, for example an interwoven knitted or textile material.
  • PFWM permeable fibre- or wire -made material
  • the combustion surface comprises a planar or a single curve region, for example in the shape of a cylindrical surface segment, at least partially formed by the first portion in the perforated metal plate, while the double curvature region is at least partially formed by the second portion in PFWM.
  • planar or single curve region for example by calendering between two calendering rollers which may even be non-heated, of the sheet metal previously perforated, and the shaping of the double curvature regions in the form of a shell by forming of the PFWM by means of a press.
  • a control or actuation member of the burner for example, an ionisation sensor, a thermal sensor, an ignition device, is positioned on the side of the combustion surface in the first portion in perforated sheet.
  • the minimum curvature radius is substantially identical (within the usual engineering tolerances for the burners in question).
  • This particular form of the diffuser layer improves the thermal exchange between the flame and the diffuser layer, increasing the thermal radiation of the combustion membrane and reducing the thermal convection through the hot fumes, with benefits for the reduction of CO and NO x .
  • a gas burner 1 for a boiler comprises a combustion membrane 2 with a diffuser layer 3 in the shape of a three-dimensional shell forming an outer combustion surface 4 with at least one double-curvature region 5, wherein the combustion surface 4 comprises a first portion 6 formed by a perforated metal sheet, and a second portion 7 formed by a permeable fibre- or thread-based material.
  • the combustion surface 4 comprises a planar or single curve region 8 , for example in the shape of a cylindrical surface segment, at least partially formed by the first portion 6 in the perforated metal sheet, while the double curvature region 5 is at least partially formed by the second portion 7 in PFWM.
  • PFWM e.g. mesh
  • the burner 1 comprises a control or actuation member 9, for example an ionisation sensor, a thermal sensor, a flame detector or an ignition device, which is positioned on the side of the combustion surface 4 at (that is above) the first portion 6 in perforated metal sheet, for example at a distance from 0mm to 12mm, preferably from 4 mm to 12 mm from the combustion surface 4.
  • a portion of said control member 9 may also extend at the second portion 7.
  • a control member 9 for example a thermocouple, is integrated in the combustion membrane 2 in the first portion 6 in perforated metal sheet, in particular it may be housed in a seat (through-hole) of said sheet.
  • the diffuser layer 3 and, consequently, the combustion surface 4 have a "semi-cigar” shape with a semi-cylindrical central portion 10 and two end portions 11 in a quarter of a sphere (the terms “semi” and “quarter” indicate a preferred embodiment, but are not limitative of the opening angle ( ⁇ ) of the profile of the diffuser layer 3 which may vary, depending on the embodiment, within reasonable limits of e.g. +/- 30°).
  • the minimum radius of curvature is substantially identical.
  • the semi-cylindrical central portion 10 is rectilinear in longitudinal section with a maximum radius of curvature ( ⁇ ) and semi-circular in cross-section with a minimum radius of curvature Rmin.
  • the end portions 11 in the form of a segment of a spherical cap have a single radius of curvature Rmin in all section planes, the curvature radius is preferably identical to the minimum radius of curvature Rmin of the central portion 10.
  • This particular form of the diffuser layer 3 improves the heat exchange between the flame and the diffuser layer 4, increasing the thermal radiation of the combustion membrane 2 and reducing the thermal convection through the hot fumes, with benefits for the reduction of CO and NO x .
  • the orthogonal direction to the combustion surface is transversal (not parallel) to the feed direction 31 of the fuel mixture on almost the entire extension of the combustion membrane (with the exception of only the summit line of the semi-cylindrical central portion 10).
  • the feed direction 31 of the flow of combustible mixture is substantially parallel to the combustion surface at its outer edge, resulting in an approximately null component perpendicular to the membrane. This way it is possible to reduce the flow of the mixture at the outer edges and avoid the phenomenon of detachment of the flame, even with elevated power modulations.
  • the component of normal flow to the combustion surface is minimum at the perimeter edges and maximum at the vertex of the arc of circumference which constitutes the cross-section of the burner.
  • This phenomenon compensates the lowering of the temperature characteristic of the connection ends to the frame, thus avoiding the detachment of the flame in such critical areas.
  • a further effect of synergy between the shape of the combustion membrane 2 and the configuration of the diffuser layer 3 in different materials is that, on the feed side of the combustion membrane 2, the flow of mixture along the diffuser layer 3 is facilitated by the first portion 6 in metal sheet towards the second portion 7 in PFWM and slowed down in the opposite direction.
  • This effect was observed during experimental tests of the burner and may be attributable to the different roughness of the two metal and PFWM materials on the feed side 17.
  • the first portion 6 in perforated sheet has at least a first zone 27 with permeability (ratio between the surface of the holes and the total surface) less than the permeability of a second zone 28 of the first portion 6, so as to deviate, on the feed side 17, a partial flow of the flow of fuel mixture from the first zone 27 to the second zone 28.
  • the first zone 27 may be formed where the combustion surface 4 is substantially perpendicular to the direction 31 of the feed flow of the mixture, for example along a summit line 29 of the burner 1.
  • the first zone 27 may comprise extensive areas free of holes.
  • the control member 9 flame detector, ignition device
  • the combustion membrane 2 is connected to a support frame 12 for the stabilisation of the burner and its attachment to a utility, in particular to a combustion chamber of a boiler.
  • the attachment of the combustion membrane 2 and the support frame 12 takes place via a securing edge 13 which projects from an outer perimeter 14 of the combustion membrane 2 and is attached, for example welded 23, crimped, wedged, glued or sandwiched to a corresponding edge 15 of the support frame 12.
  • the securing edge 13 may be made from the same material as the membrane 2, for example by folding a perimetral region thereof, but is superposed to the frame 12 (on the combustion side 16 or on the feed side 17, Figures 2, 3 and 17 ) and does not permit the passage of the fuel mixture or the formation of the flame.
  • the securing edge 13 is not considered comprised in the definition of "combustion membrane 2".
  • the inner edge 15 of the frame 12 defines a support line of the combustion membrane 2 which preferably, but not necessarily, lies in a plane.
  • the perforated metal sheet or a free edge thereof may frontally abut or superpose the PFWM or a free edge thereof.
  • the two different materials may be joined by spot welding, continuous bead welding or interrupted bead welding, crimping, pressing, riveting, or by stitching with clips or staples or, alternatively, by means of simple side-by-side positioning without structural connection along the meeting line of the two materials.
  • the boundary (or meeting), and the connection between the first portion 6 and the second portion 7 is made along a line extending in a plane or a surface with simple or planar curvature ( figures 3 , 8 ).
  • the layer of PFWM 19 is reinforced and supported all over its extension by means of a wire mesh 21 which essentially follows its three-dimensional shape and forms part of the combustion membrane 2.
  • the burner 1 comprises a distributor 22 for distributing the fuel mixture in a desired manner towards the diffuser layer 3.
  • the distributor 22 comprises one or more walls with a plurality of through openings, for example in perforated sheet or a wire mesh, and may form an inner layer (the feed side 17) of the combustion membrane 2 or, alternatively, a component spaced from the combustion membrane 2.
  • the burner 1 comprises one or more separation partitions 24 which delimit a plurality of feed compartments 25, 26 of the fuel mixture upstream of the combustion membrane 2.
  • At least a first feed compartment 25 is in flow communication with (or, in other words, conveys the fuel mixture to) at least a part of the first portion 6 of the combustion surface 4 and at least a second feed compartment 26 is in flow communication with (or, in other words, conveys the fuel mixture) to at least a part of the second portion 7 of the combustion surface 4.
  • an insert made of metal sheet may be provided for which forms both the distributor 22 and the separating partitions 24, for example an approximately semi-cylindrical sheet metal insert with a perforated wall which forms the distributor 22 and two separation partitions 24 which protrude:
  • the separation partitions 24 preferably extend at a distance from the free edges of the perforated wall of the distributor insert in such a way as to constitute a reinforcement rib against unwanted thermal deformations and vibrations.
  • the perforated wall of the distributor insert substantially extends over the whole extension of the first portion 6 of the combustion surface 4, obviously, on the feed side 17 of the diffuser layer 3.
  • the sheet metal of the insert shields the flow of mixture from the thermal retro-irradiation of the diffuser layer 3 which is much stronger in the first portion 6 of sheet metal than in the second portion 7 in PFWM.
  • the mixture arriving at the diffuser layer is then cold enough to cool the diffuser layer and overcome problems of instability of the flame.
  • the shielding effect of the distributor thus configured reduces the noise of the burner in the low and high frequencies and improves combustion with mixtures having a reduced fuel content (lean mixtures).
  • the fuel mixture can no longer flow out of the first portion in sheet metal 6 toward the second portion 7 in PFWM.
  • the separation partition (s) 24 may be positioned in such a way as not obstruct a flow of the mixture from the second portion 7 towards said zone of intense passage.
  • the separation partitions 24 may protrude from the perforated wall of the distributor 22 in a position spaced from a free edge thereof 30.
  • fuel mixture used in the description of the invention indicates a mixture of a combustible gas and an oxidising gas or, alternatively, a fuel gas.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Gas Burners (AREA)
EP14194802.6A 2013-11-26 2014-11-25 Gas burner Withdrawn EP2876369A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT001968A ITMI20131968A1 (it) 2013-11-26 2013-11-26 Bruciatore

Publications (1)

Publication Number Publication Date
EP2876369A1 true EP2876369A1 (en) 2015-05-27

Family

ID=50001125

Family Applications (1)

Application Number Title Priority Date Filing Date
EP14194802.6A Withdrawn EP2876369A1 (en) 2013-11-26 2014-11-25 Gas burner

Country Status (2)

Country Link
EP (1) EP2876369A1 (it)
IT (1) ITMI20131968A1 (it)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018050578A1 (en) 2016-09-13 2018-03-22 Bekaert Combustion Technology B.V. Premix gas burner
IT201700062133A1 (it) * 2017-06-07 2018-12-07 Worgas Bruciatori Srl Bruciatore
EP3617594A1 (en) * 2018-08-31 2020-03-04 Grand Mate Co., Ltd. Combustion device
JP2020134086A (ja) * 2019-02-25 2020-08-31 リンナイ株式会社 全一次燃焼式バーナ
US11022303B2 (en) 2018-10-18 2021-06-01 Grand Mate Co., Ltd. Combustion device

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1105757A (en) * 1966-10-25 1968-03-13 Caloric Internat Inc Improvements in or relating to radiant burners
DE10228411C1 (de) * 2002-06-25 2003-09-18 Enginion Ag Porenbrenner mit verringerter Startemission
WO2004092647A1 (en) * 2003-04-18 2004-10-28 N.V. Bekaert S.A. A metal burner membrane
GB2437976A (en) * 2006-05-09 2007-11-14 Valor Ltd Burner assembly for gaseous fuel
WO2012095759A1 (en) 2011-01-13 2012-07-19 Telefonaktiebolaget Lm Ericsson (Publ) Reduced bandwidth backhaul for coordinated multi-point receipt
WO2012095799A2 (en) * 2011-01-12 2012-07-19 Worgas Bruciatori S.R.L. High perimeter stability burner
WO2012152571A1 (en) * 2011-05-06 2012-11-15 Bekaert Combustion Technology B.V. Premix gas burner with temperature measurement

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1105757A (en) * 1966-10-25 1968-03-13 Caloric Internat Inc Improvements in or relating to radiant burners
DE10228411C1 (de) * 2002-06-25 2003-09-18 Enginion Ag Porenbrenner mit verringerter Startemission
WO2004092647A1 (en) * 2003-04-18 2004-10-28 N.V. Bekaert S.A. A metal burner membrane
GB2437976A (en) * 2006-05-09 2007-11-14 Valor Ltd Burner assembly for gaseous fuel
WO2012095799A2 (en) * 2011-01-12 2012-07-19 Worgas Bruciatori S.R.L. High perimeter stability burner
WO2012095759A1 (en) 2011-01-13 2012-07-19 Telefonaktiebolaget Lm Ericsson (Publ) Reduced bandwidth backhaul for coordinated multi-point receipt
WO2012152571A1 (en) * 2011-05-06 2012-11-15 Bekaert Combustion Technology B.V. Premix gas burner with temperature measurement

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018050578A1 (en) 2016-09-13 2018-03-22 Bekaert Combustion Technology B.V. Premix gas burner
CN112050208A (zh) * 2016-09-13 2020-12-08 贝卡尔特燃烧技术股份有限公司 预混气体燃烧器
IT201700062133A1 (it) * 2017-06-07 2018-12-07 Worgas Bruciatori Srl Bruciatore
EP3412968A1 (en) * 2017-06-07 2018-12-12 Worgas Bruciatori S.R.L. Burner
EP3617594A1 (en) * 2018-08-31 2020-03-04 Grand Mate Co., Ltd. Combustion device
US11022303B2 (en) 2018-10-18 2021-06-01 Grand Mate Co., Ltd. Combustion device
JP2020134086A (ja) * 2019-02-25 2020-08-31 リンナイ株式会社 全一次燃焼式バーナ

Also Published As

Publication number Publication date
ITMI20131968A1 (it) 2015-05-27

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