EP0844435A1 - Gasbrenner - Google Patents

Gasbrenner Download PDF

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Publication number
EP0844435A1
EP0844435A1 EP96830593A EP96830593A EP0844435A1 EP 0844435 A1 EP0844435 A1 EP 0844435A1 EP 96830593 A EP96830593 A EP 96830593A EP 96830593 A EP96830593 A EP 96830593A EP 0844435 A1 EP0844435 A1 EP 0844435A1
Authority
EP
European Patent Office
Prior art keywords
tubular element
semi
tubular
upper semi
burner according
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Withdrawn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
EP96830593A
Other languages
English (en)
French (fr)
Inventor
Feliciano Lasagni
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
Priority to EP96830593A priority Critical patent/EP0844435A1/de
Publication of EP0844435A1 publication Critical patent/EP0844435A1/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Withdrawn legal-status Critical Current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
    • F23D14/105—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 with injector axis parallel to the burner head axis
    • 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
    • F23D2203/1026—Flame diffusing means using perforated plates with slotshaped openings
    • 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 gas burner, either of the atmospheric or premix type.
  • the invention relates in particular to a gas burner with a high resistance to stress resulting from thermal expansion.
  • Gas burners known in prior art may be divided into two categories, namely, atmospheric burners and premix burners.
  • Atmospheric burners usually comprise a tubular casing, closed at both ends and coaxially enclosing a venturi tube consisting of a converging portion, a cylindrical throat and a diverging portion.
  • the venturi tube may be a separate part fitted in the burner or it may form an integral part of the burner itself, made, for example, by die forming or other known methods.
  • the said tubular casing has a plurality of flame ports, usually at the top, designed to allow a combustion mixture of gas and air to flow out of it.
  • a nozzle injects gas into the opening of the venturi tube and, in accordance with the known principles of fluid mechanics, a certain quantity of air is also sucked into the opening of the venturi tube and mixes well with the gas in the aforesaid cylindrical throat.
  • the gas/air mixture in the desired and controlled stoichiometric proportions, is then dynamically compressed in the said diverging portion, is discharged into the tubular casing and allowed through the said flame ports into the atmosphere where it is burnt.
  • the gas and air are supplied by means (consisting typically of fans and mixers) which, in a manner similar to that achieved by the venturi device described above, create a premixture of gas and air outside the tubular casing and supply the combustion mixture to the aforesaid flame ports.
  • the mixture is ignited through auxiliary systems that do not form part of the subject-matter of the present invention.
  • the configuration and size of the aforesaid ports are such as to prevent the flame from returning into the tubular casing of the burner but to keep it adjacent to the outer surface of the casing.
  • the flame ports may assume many different sizes and configurations. For example, they may be continuous rows of slits or groups of slits arranged in chequered fashion, offset with respect to each other, or they may be appropriately distributed holes or combinations of slits and holes distributed in any of various different ways, made in a lateral portion (which may even coincide with the entire lateral surface) of the tubular casing which will hereafter be referred to as the "flame port area".
  • the distance of the flame front from the surface of the tubular casing depends on the type of gas used, on the gas supply pressure and on the shape of the burner. In all cases, because of the nearness of the flame to the said tubular casing, a portion of the tubular casing itself (namely, the flame port area), depending on the type and category of the burner, reaches extremely high temperatures, with peaks of up to 600°C and over. In particular, under certain operating conditions, not frequent in well designed and constructed burners but always possible even in these, the temperature of at least part of the surface of the tubular casing (that around the flame port area) may become so high as to produce considerable deformation, resulting in stress and strain, in particular on the sides of the tubular casing.
  • This deformation if excessive in that it is normally prevented, is permanent and may lead to burner breakage or malfunctioning even when the overheating ceases. In some cases, such deformation may also make it dangerous to continue using the burner, producing a risk of serious damage to the apparatus where it is fitted or even to the room where it is used.
  • the aim of the present invention is to overcome the disadvantages mentioned above by providing a burner capable of resisting abnormally high temperatures without being permanently deformed and without reducing its efficiency or giving rise to hazardous situations.
  • a gas burner of the type comprising a tubular casing closed at its axially opposite ends and enclosing a mixing element capable, when used, of creating a mixture of gas and air inside the tubular casing, characterized in that the said tubular casing is divided into a lower semi-tubular element with concavity facing up and an upper semi-tubular element with concavity facing down; the said lower and upper semi-tubular elements extending longitudinally along parallel axes, the upper semi-tubular element having a plurality of flame ports to allow the combustion mixture of gas and air out of the tubular casing and the said lower and upper semi-tubular elements being joined to each other through a substantially fluid tight connection and in such a way that each element can expand independently of the other in axial direction.
  • One of the advantages achieved by the present invention is basically that the tubular casing of the burner disclosed can be subjected to extremely high thermal shocks (on the upper and lower semi-tubular elements) without producing permanent deformations that can damage it or make its use dangerous.
  • the numeral 1 indicates a gas burner as a whole, represented in the atmospheric version by way of example only, without thereby restricting the scope of the inventive concepts which may be applied also to burners of the premix type.
  • the burner 1 comprises a tubular casing 2 extending lengthways along an axis 3 which, when the burner is in use, is horizontal.
  • the tubular casing 2 in cross section, forms a closed shape (in the embodiment illustrated, see Fig. 3, it is substantially ovoid in shape) with one end, illustrated on the right in Fig. 1, closed by a vertical end cap 5 and the other end, on the left-hand side, being closed by a flange 4 with a gas and air inlet port.
  • a mixing element consisting of a venturi tube 6 extending along an axis parallel to the axis 3 and comprising, from left to right in Fig. 1, a converging portion 7, a cylindrical throat 8 and a diverging portion 9.
  • a feeder element consisting of a nozzle 10, faces the inlet port of the tubular casing 2 through a hole 11 made in the central portion of the flange 4 (the inlet port mentioned above), being fitted at the inlet of the converging portion 7 so that, under operating conditions, it can inject a stream of gas into the converging portion 7 according to known injector technology.
  • the wall defining the lateral surface of the tubular casing 2 is divided into two portions, namely, a lower, elongated semi-tubular element 12, with concavity facing up and constituting the lower section of the tubular casing 2, and an upper, elongated semi-tubular element 13, with concavity facing down and constituting the upper section of the tubular casing 2.
  • the two lower, horizontal edges of the upper semi-tubular element 13 are connected each to two longitudinal, parallel protrusions 14, whose length is (preferably) equal to the upper semi-tubular element 13 itself.
  • These longitudinal protrusions 14, which hereafter will also be referred to as "guide means”, basically constitute extensions of the corresponding edge of the upper semi-tubular element 13 and the spacing between them is slightly wider than the thickness of the lower semi-tubular element 12.
  • Each of the two upper horizontal edges of the lower semi-tubular element 12 is designed to slide into the space between two corresponding pairs of longitudinal protrusions 14 of the upper semi-tubular element 13 (in such a way as to form a sliding fit); the relative seal is determined by the length of the fit and by the closeness between the overlapping surfaces in such a way as to define a sort of localized leakage labyrinth seal.
  • the axial ends of the lower semi-tubular element 12 are rigidly connected to the aforesaid flange 4 and end cap 5, whilst one of the axial ends of the upper semi-tubular element 13 is connected to the flange 4 or to the end cap 5 (in a manner illustrated schematically because it is obvious to experts in the trade) in such a manner that, although the connection between the upper semi-tubular element 13 and the flange 4 or the end cap 5 offers a substantially fluid tight seal, at least one of the said axial ends, preferably the one labelled 13m connected to the end cap 5, can move in the axial direction. In the embodiment illustrated, the left-hand end 13f is fixed.
  • both ends might be left free to move.
  • a portion of the upper semi-tubular element 13, the top portion in the embodiment illustrated, has an area with a plurality of flame ports 15, starting at distances L1 and L2 from the ends of the tubular casing 2 and hereafter referred to as "flame port area" 13a.
  • the flame ports consist of a series of apertures (preferably but not necessarily slits) parallel to each other and perpendicular to the aforesaid axis 3.
  • These flame ports 15 may be arranged in any manner, typically along one or more adjacent longitudinal rows (see Fig. 7) or in shorter polygonal groups arranged in line or in chequered fashion (see Fig. 8) or, as mentioned in the introduction, they may be circular, as illustrated in Fig. 9.
  • the gas is injected into the venturi tube 6 through the nozzle 10 and entrains a flow of air through an appropriate port (not illustrated) made in the aforementioned flange 4.
  • the streams of air and gas enter the converging portion 7 of the venturi tube 6 together and are well mixed before leaving the venturi tube 6 through the diverging portion 9.
  • the gas/air mixture then leaves the tubular casing 2 through the flame ports 15 and is ignited by known means outside the tubular casing 2 adjacent to the flame ports 15.
  • the tubular casing 2 When the burner 1 is cold, the tubular casing 2 has the nominal dimensions, depending on burner design, and is not subjected to stress.
  • the entire tubular casing 2 starts to expand in the axial direction and there is more thermal expansion around the flame port area 13a of the upper semi-tubular element 13 than there is on the semi-tubular element 12 since the area 13a is in direct contact with, or in the vicinity of, the flame.
  • the difference in the thermal expansion does not subject the upper semi-tubular element 13 to dangerous stress (and even less so the lower semi-tubular element 12) since the upper semi-tubular element 13 is connected in such a way as to allow it to slide axially relative to the semi-tubular element 12 thanks to the aforementioned fit between its longitudinal protrusions 14 and the edges of the lower semi-tubular element 12 itself, the upper semi-tubular element 13 being, therefore, free to expand without obstructions.
  • the semi-tubular element 13 can expand freely with respect to the element 12 below it, thus making it possible to avoid the peak strain conditions mentioned above.
  • Figs. 4 to 6 illustrate a burner 16 constituting an alternative embodiment of the burner 1 described above. Where possible, the parts of the burner 16 are labelled with the same reference numbers as the corresponding parts of the burner 1.
  • the upper semi-tubular element 13 does not have the longitudinal protrusions 14 but is placed directly onto the upper open end of the lower semi-tubular element 12.
  • the element 12 has an opening 12s which is slightly larger than the aforementioned flame port area 13a. As shown in Fig. 5, in the preferred embodiment, the opening 12s is longer than the flame port area and, for this reason, the distances L3 and L4 from the ends of the tubular casing 17 are shorter than the distances L1 and L2 mentioned previously.
  • the numeral 20 in Fig. 6 indicates generic upper guide means (not essential) for the upper semi-tubular element 13, two portions 13b of whose edge are placed over and in contact with the corresponding portions 12b of the edge of the lower semi-tubular element 12.
  • the means 20 are designed to prevent the end portions 13b of the edges of the upper semi-tubular element 13 from being “lifted off” the corresponding edges 12b below and breaking the seal when the upper semi-tubular element 13 expands.
  • guides 20g whose lower ends are integral with the lower semi-tubular element 12 and whose upper ends overlap the upper semi-tubular element 13.
  • bands 20f distributed along the length of the semi-tubular elements 12 and 13 and overlapping both elements (see Figs. 4 and 6).
  • the axial ends of the lower semi-tubular element 12 are rigidly connected to the aforesaid flange 4 and end cap 5, whilst one of the axial ends of the upper semi-tubular element 13 is connected to the flange 4 or to the end cap 5 (in a manner illustrated schematically because it is obvious to experts in the trade) in such a manner that, although the connection between the upper semi-tubular element 13 and the flange 4 or the end cap 5 offers a substantially fluid tight seal, at least one of the said axial ends, preferably the one labelled 13m connected to the end cap 5, can move in the axial direction. In the embodiment illustrated, the left-hand end 13f is fixed.
  • both ends might be left free to move.
  • the burner 16 works in exactly the same way as the burner 1.
  • the expansion of the upper semi-tubular element 13 occurs in the same way as that described with reference to the burner 1, that is, without any obstructions and without creating undue strain capable of damaging the upper semi-tubular element 13.
  • the burners 1 and 16 fully achieve the abovementioned aims in that they are capable of withstanding overheating (or high temperature differences between the upper and lower elements) of the surfaces directly concerned without creating permanent deformations in the burners 1 and 16 such as to reduce their efficiency or give rise to hazardous situations.
  • Fig. 5 indicates the generic element 6p for premixing the gas and air mixture outside the tubular casing 2, the said mixture being then forced into the tubular casing under pressure to reach the combustion area.
  • the longitudinal protrusions 14 might be integral with the upper horizontal edges of the lower semi-tubular element 12 and the lower edges of the upper semi-tubular element 13 might be housed between corresponding pairs of longitudinal protrusions 14.

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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)
EP96830593A 1996-11-26 1996-11-26 Gasbrenner Withdrawn EP0844435A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP96830593A EP0844435A1 (de) 1996-11-26 1996-11-26 Gasbrenner

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP96830593A EP0844435A1 (de) 1996-11-26 1996-11-26 Gasbrenner

Publications (1)

Publication Number Publication Date
EP0844435A1 true EP0844435A1 (de) 1998-05-27

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Family Applications (1)

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EP96830593A Withdrawn EP0844435A1 (de) 1996-11-26 1996-11-26 Gasbrenner

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EP (1) EP0844435A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1036983A1 (de) * 1999-03-18 2000-09-20 Worgas Bruciatori S.R.L. Rohrbrenner
WO2004005799A1 (en) * 2002-04-19 2004-01-15 Cast S.R.L. Oven or grill burner, venturi tube, mounting for a thermocopuple and/or an igniter, and process for fabricating said burner

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2305689A1 (fr) * 1975-03-27 1976-10-22 Burnham Europa Bv Bruleur a gaz pourvu d'un corps et d'un couvercle muni d'orifices de sortie de gaz
EP0314897A1 (de) * 1987-10-31 1989-05-10 Ruhrgas Aktiengesellschaft Überstöchiometrisch vormischender Gasbrenner für Gasheizgeräte
US4830600A (en) * 1988-01-19 1989-05-16 American Standard Inc. Premix furnace burner
WO1992012381A1 (de) * 1991-01-07 1992-07-23 Ruhrgas Aktiengesellschaft Gasbrenner und verfahren zu seinem betreiben
DE29513653U1 (de) * 1995-08-25 1995-11-02 Buderus Heiztechnik Gmbh, 35576 Wetzlar Brennstab für Gasbrenner

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2305689A1 (fr) * 1975-03-27 1976-10-22 Burnham Europa Bv Bruleur a gaz pourvu d'un corps et d'un couvercle muni d'orifices de sortie de gaz
EP0314897A1 (de) * 1987-10-31 1989-05-10 Ruhrgas Aktiengesellschaft Überstöchiometrisch vormischender Gasbrenner für Gasheizgeräte
US4830600A (en) * 1988-01-19 1989-05-16 American Standard Inc. Premix furnace burner
WO1992012381A1 (de) * 1991-01-07 1992-07-23 Ruhrgas Aktiengesellschaft Gasbrenner und verfahren zu seinem betreiben
DE29513653U1 (de) * 1995-08-25 1995-11-02 Buderus Heiztechnik Gmbh, 35576 Wetzlar Brennstab für Gasbrenner

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1036983A1 (de) * 1999-03-18 2000-09-20 Worgas Bruciatori S.R.L. Rohrbrenner
WO2004005799A1 (en) * 2002-04-19 2004-01-15 Cast S.R.L. Oven or grill burner, venturi tube, mounting for a thermocopuple and/or an igniter, and process for fabricating said burner
US7506645B2 (en) 2002-04-19 2009-03-24 Castifutura S.P.A. Oven or grill burner, venturi tube, mounting for a thermocouple and/or an igniter, and process for fabricating said burner

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