EP0892213A1 - Filterbettbrenner und damit durchgeführtes Gasverbrennungsverfahren - Google Patents

Filterbettbrenner und damit durchgeführtes Gasverbrennungsverfahren Download PDF

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Publication number
EP0892213A1
EP0892213A1 EP97830358A EP97830358A EP0892213A1 EP 0892213 A1 EP0892213 A1 EP 0892213A1 EP 97830358 A EP97830358 A EP 97830358A EP 97830358 A EP97830358 A EP 97830358A EP 0892213 A1 EP0892213 A1 EP 0892213A1
Authority
EP
European Patent Office
Prior art keywords
burner
filtering bed
filtering
air
bed
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Withdrawn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
EP97830358A
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English (en)
French (fr)
Inventor
Gianmario Invernizzi
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.)
SIABS INDUSTRY S.R.L.
Original Assignee
SIABS INDUSTRY Srl
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Priority to EP97830358A priority Critical patent/EP0892213A1/de
Publication of EP0892213A1 publication Critical patent/EP0892213A1/de
Withdrawn legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23DBURNERS
    • F23D14/00Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/46Details, e.g. noise reduction means
    • F23D14/68Treating the combustion air or gas, e.g. by filtering, or moistening
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23DBURNERS
    • F23D14/00Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/02Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23DBURNERS
    • F23D14/00Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/46Details, e.g. noise reduction means
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23DBURNERS
    • F23D2203/00Gaseous fuel burners
    • F23D2203/10Flame diffusing means
    • F23D2203/101Flame diffusing means characterised by surface shape
    • F23D2203/1012Flame diffusing means characterised by surface shape tubular
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23DBURNERS
    • F23D2212/00Burner material specifications
    • F23D2212/10Burner material specifications ceramic
    • F23D2212/105Particles
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23DBURNERS
    • F23D2213/00Burner manufacture specifications

Definitions

  • the present invention relates to a filtering-bed burner of the type comprising a pre-mixing chamber to be associated with feeding means to supply an air-combustible gas mixture, and a filtering bed formed of granular elements disposed to define a delimitation wall for the pre-mixing chamber, said filtering bed being arranged so as to be passed through by the air-gas mixture that is fired close to an outer surface provided on the filtering bed itself on the opposite side relative to the pre-mixing chamber.
  • the invention also relates to a method of combustion of a gas carried out by said burner, said method comprising the steps of: pre-mixing the gas with a predetermined amount of air to form an air-gas mixture; feeding said air-gas mixture through a filtering bed defined by granular elements to cause an intimate mixing between the air and the gas forming said mixture, firing the air-gas mixture close to an outlet surface of said filtering bed.
  • burners currently used in boilers and water heaters or similar apparatuses for household and/or industrial use are essentially comprised of a mixing chamber in which a combustive air-combustible gas mixture is formed. This mixture is then ejected from the burner through a plurality of holes or shaped openings conveniently distributed on a burner wall, intended to delimit the mixing chamber.
  • the air-gas mixture is fired, thereby forming a plurality of small flames correspondingly distributed at the location of said through holes or openings provided in the burner wall.
  • one of the possible alternatives to burners provided with a perforated wall of the type described above involves employment of the so-called "filtering-bed” burners.
  • the air-gas mixture conveyed to the inside of the burner is forced to pass through a filtering bed formed of granular elements disposed in several superposed layers, to define a labyrinth formed with hollow spaces promoting an intimate mixing between the air and gas forming the mixture, said mixture being fired close to an outlet surface of the filtering bed.
  • US Patent 3,322,179 describes a burner having a filtering bed formed of a plurality of spherules or granular elements of different shape made of glass, quartz, silicon carbide or ceramic material, mutually joined at the points of mutual tangency by a sintering process and distributed to form two different superposed layers.
  • a first layer turned towards the pre-mixing chamber, is formed of spherules or granular elements of different shape having a particle size included between about 0.15 and 0.3 mm.
  • a second layer defining the outlet surface of the filtering bed, is formed of spherules or granular elements of a particle size included between 0.5 and 1 mm.
  • the filtering bed is essentially defined by a plate-like element of sintered metal particles, defined by spherules or irregular bodies. In this case too, particles are distributed to form two distinct layers.
  • a first layer of a thickness in the order of 3 mm, is formed of spherules the size of which is such selected that the interspaces defined between them have a size in the order of 0.1 mm.
  • the spherules forming the second layer of a thickness in the order of 1 mm and defining the outlet surface of the filtering bed, have such sizes that the interspaces defined between them have a diameter in the order of 0.02 mm.
  • US Patent 5,591,095 in the name of the same Applicant, discloses a burner the filtering element of which is formed of spherules of ceramic material of predetermined sizes, included by way of example between 1 and 10 mm, optionally welded together by a sintering process.
  • the mutual divergence of the spherule surfaces at the burner outlet causes the outgoing flow speed to slow down immediately downstream of the interspaces defined between the spherules themselves, even at high flow rates of the air-gas mixture conveyed through the filtering bed, thereby generating a continuous flame front confined between the spherule surfaces.
  • the flame stays always adherent to the spherule surfaces, so that a localized heating produced on said surfaces may cause incandescence thereof and consequent heat emission by radiation.
  • the filtering bed of granular elements of irregular shape having a particle size included between 2.5 and 7 mm, preferably between 3 and 5 mm and randomly laid down upon each other so as to form an overall thickness included between 10 and 20 mm, the possibility of making the burner operate in an optimal manner, also modulating the flow rate value of the air-gas mixture within exceptionally wide value ranges, is advantageously achieved.
  • Such a burner can be in addition produced at very reduced costs, comparable to those of conventional burners provided with a perforated plate, even in the case in which the burner is of cylindrical form.
  • the invention relates to a filtering-bed burner characterized in that said filtering bed of a thickness included between 10 mm and 20 mm, is made up of granular elements of irregular shape, having a particle size included between 2.5 and 7 mm, randomly disposed upon each other.
  • a preferential solution of a burner of cylindrical form is obtained according to a process which is characterized in that it comprises the following steps: forming an inlet header having a base wall in the form of an annulus, as well as an outer perimetric wall and an inner perimetric wall substantially extending at right angles from respectively opposite perimetric edges of the base wall; associating first and second concentrically-disposed holding nets with said outer perimetric wall and said inner perimetric wall respectively; filling a space defined between said holding nets at least partly with granular elements disposed randomly against each other so as to define a filtering bed; forming a closing element having a connecting portion of shape and sizes substantially identical with those of the inlet header, and a closing wall; causing engagement of an inner perimetric wall and an outer perimetric wall of said connecting portion respectively with the first and second holding nets on an opposite side relative to the inlet header.
  • a filtering-bed burner in accordance with the present invention has been generally identified by reference numeral 1.
  • Burner 1 comprises a pre-mixing chamber 2 to be operatively associated with feeding means for supply of an air-gas mixture, said means being only diagrammatically shown in that it can be made in a manner known per se and conventional.
  • Burner 1 further comprises at least one filtering bed 3 arranged to define, by its inlet surface 3a, at least one wall delimiting the pre-mixing chamber 2.
  • the pre-mixing chamber 2 is directly defined within the filtering bed 3 and circumscribed by the inlet wall 3a of the filtering bed, the latter being made of a cylindrical tubular form, preferably of circular section.
  • the filtering bed 3 is adapted to be passed through by the air-gas mixture introduced into the pre-mixing chamber 2 which is fired at the outside of the burner, close to an outlet surface 3b provided by the filtering bed on the opposite side relative to the pre-mixing chamber 2.
  • the pre-mixing chamber 2 is connected to the feeding means 1a by an inlet header 4 associated with one end 3c of the filtering bed 3.
  • the inlet header 4 is preferably made of a die-cut and drawn metal sheet and has a base portion 4a in the form of an annulus which is such disposed that the first end 3c of the filtering bed 3 is delimited thereby.
  • Header 4 further has an outer perimetric portion 4b of cylindrical conformation extending in a substantially perpendicular direction from an outer perimetric edge of the base portion 4a.
  • an inner perimetric portion 4c which is also extended in a direction substantially perpendicular to the base portion 4a and has a substantially cylindrical conformation.
  • Burner 1 further has a closing element 5 associated with a second end 3d of the filtering bed 3, on the opposite side relative to the inlet header 4.
  • this closing element 5 has a connecting portion 6 the shape and sizes of which are substantially identical with those of the inlet header 4, and a closing wall 7 arranged to close the end of the pre-mixing chamber 2.
  • the connecting portion 6 of the closing element 5 has a respective base wall 6a in the form of an annulus, so as to delimit the second end 3d of the filtering bed 3, as well as an outer perimetric wall 6b and an inner perimetric wall 6c extending at right angles and in opposite directions from an outer perimetric edge and an inner perimetric edge respectively of the base wall 6a.
  • the closing wall 7 extends in a diametrical plane from an end edge of the inner perimetric wall 6c.
  • the closing element 5, of a conformation and structure substantially identical with those of the inlet header 4 is adapted to be made with the aid of the same machines and equipment as employed for making the header itself.
  • both elements are obtained by carrying out die-cutting and drawing of a metal sheet, it will be possible to produce these two components with one and the same mould by arranging a movable punch in said mould, which is adapted to selectively cause either forming of the closing wall 7 so as to obtain the closing element 6, or removal of the metal sheet portion corresponding to such a wall so as to form the inlet header 4.
  • header 4 can have the same orientation as the connecting portion 6 of the closing element 5, as shown in Fig. 1, or it may be disposed in mirror image relationship relative to this connecting portion 6, as shown in Fig. 2.
  • the filtering bed 3 is substantially formed of a homogeneous mixture of granular elements 8 of irregular shape, preferably of crystallized silicon dioxide, having differentiated particle sizes of a value included between 2.5 and 7 mm, and preferably included between 3 and 5 mm.
  • the embodiment involving granular elements of different size homogeneously mixed with each other is preferred in that it has been found that it enables a more efficient mixing between the air and gas forming the mixture admitted to the pre-mixing chamber 2.
  • employment of granular elements of same size, the particle size of which is included within the above specified value ranges, may be also taken into account.
  • the granular elements 8 are freely and randomly disposed against each other to fill a space defined between a first holding net 9 extending at the inlet surface 3a of the filtering bed 3 and a second holding net 10 extending at the outlet surface 3b.
  • the first and second nets 9 and 10 have a cylindrical configuration and are concentrically disposed with respect to each other.
  • Each of the holding nets 9, 10 can be made either of a metal wire for example, or of a die-cut and optionally stretched metal sheet so as to form the net meshes by spreading apart cuts produced by the die-cutting operation.
  • the holding nets have the same mesh width as the particle size of the smallest granular elements or a slightly smaller width.
  • the holding nets are adapted to carry out an efficient holding action of the granular elements 8 without putting up too much resistance to the air-gas mixture passage.
  • thickness of said bed is provided to be included between 10 and 20 mm.
  • the first holding net 9 is fastened by its opposite end edges 9a, 9b to the inner perimetric walls 4c, 6c provided by the inlet header 4 and the connecting portion 6 of the closing element 5, respectively.
  • the outer holding net 10 has its opposite end edges 10a, 10b fastened to the outer perimetric walls 4b, 6b belonging to the inlet header 4 and the closing element 5, respectively.
  • the first holding net 9 is internally in engagement both with the inner perimetric wall 6c of the closing element 5 and the inner perimetric wall 4c of header 4.
  • the second holding net 10 is engaged externally of the outer perimetric wall 6b of the closing element 5 and externally of the outer perimetric wall 4b of header 4.
  • both holding nets 9, 10 are engaged internally of the corresponding perimetric walls 4b, 4c, 6b, 6c belonging to the header 4 and closing element 5.
  • Connection between nets 9, 10 and header 4, as well as the closing element 5, can be carried out by welding, for example.
  • At least one insulating element 11, preferably made of an elastically-yielding refractory material, a ceramic fibre for example, may be interposed between at least one of the filtering bed 3 ends and the corresponding base wall 6a, 4a of the closing element 5 and/or header 4.
  • burner 1 further comprises at least one shielding element 12 extending from the closing element 5 close to the inlet surface 3a of the filtering bed 3, to the inside of the pre-mixing chamber 2.
  • this shielding element 12 extends axially over at least 1/10 of the axial length of the filtering bed past the corresponding end 3d of the filtering bed 3 itself. Owing to the presence of the shielding element 12, distribution of the air-gas mixture through the filtering bed 3 is made still more homogeneous, thereby eliminating the undesired effect of overpressures that are likely to be created close to the corresponding end 3d of the filtering bed, due to the presence of the closing wall 7 that suddenly stops mixture advancing along the pre-mixing chamber 2.
  • a second shielding element 13 may be also provided and it extends from the inlet header 4 close to the inlet surface 3a of the filtering bed 3 to the inside of the pre-mixing chamber 2.
  • This second shielding element 13 can be either defined by the inner perimetric wall 4c of header 4, as shown in Fig. 1, or made as an extension of said wall.
  • the second shielding element 13 can be coaxially inserted in the inner perimetric wall of header 4.
  • the burner in accordance with the invention can be advantageously obtained by a process first providing fastening, by welding for example, of the first and second holding nets 9, 10 to the inlet header 4. Subsequently the interspace defined between nets 9, 10 is filled with the granular elements 8 forming the filtering bed 3.
  • the closing element 5 is fitted to the holding nets 9, 10 and fastened to the first holding net 9 by welding, for example. Concurrently with, or before engagement of the closing element 5, insertion of the optional shielding element or elements 12 is carried out.
  • assembling can be also executed with a reverse sequence with reference to the above described one, that is the holding nets 9, 10 are first engaged in the closing element 5, whereas mounting of header 4 is executed once the filtering bed 3 has been formed by introduction of the granular elements 8.
  • the insulating elements 11 are provided, important tolerances in the axial size of the filtering bed 3 are enabled. Actually, the elastically-yielding insulating element or elements 11 act on the filtering bed ends causing compacting of said bed on mounting of the closing element 5 and/or header 4. In addition, the insulating elements 11 prevent the flame produced by combustion from being propagated internally of the outer perimetric wall 6b, 6c of the closing element 5 and/or header 4, thereby giving rise to an undesired overheating of said element 5 and header 4.
  • the insulating elements enable compensation for thermal expansions undergone by the material during operation of the burner.
  • the feeding means 1a is advantageously arranged to feed the air-gas mixture at a specific flame power included between a minimum value of about 25 W/cm 2 and a maximum value of about 350 W/cm 2 .
  • the feeding means 1a may be of a type capable of modulating the air-gas mixture flow rate so as to adjust the specific power flame at each moment depending on requirements within a value range included between said minimum and maximum values.
  • the feeding means is also preferably provided for the feeding means to be of the type capable of supplying a greatly hyperstoichiometric air-gas mixture, with an oxygen excess in the combustion fumes included between 3.5% and 9%.
  • the outgoing flow rate can be in any case maintained, by increasing the air percentage in the air-gas mixture for example, to such a level that the flame stays slightly detached from the outlet surface of the filtering bed, so that undesired overheating of the second holding net 10 and the granular elements 8 located close to the outlet surface 3b is not caused.
  • Heat dissipation by radiation can be also achieved by arranging an auxiliary radiating net-like element 14 (shown in chain line in Fig. 1) to a position conveniently spaced apart from the outlet surface of the filtering bed 3.
  • the present invention achieves the intended purposes.
  • the burner in reference enables operation to be carried out in a greatly adjustable manner and ensures an excellent combustion at any load level, while at the same time having production costs comparable with those of standard perforated-plate burners.
  • CO emission is lower than 10 ppm and NOx emission is lower than 20 ppm.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
EP97830358A 1997-07-16 1997-07-16 Filterbettbrenner und damit durchgeführtes Gasverbrennungsverfahren Withdrawn EP0892213A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP97830358A EP0892213A1 (de) 1997-07-16 1997-07-16 Filterbettbrenner und damit durchgeführtes Gasverbrennungsverfahren

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP97830358A EP0892213A1 (de) 1997-07-16 1997-07-16 Filterbettbrenner und damit durchgeführtes Gasverbrennungsverfahren

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EP0892213A1 true EP0892213A1 (de) 1999-01-20

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1731836A1 (de) * 2005-06-08 2006-12-13 Robert Bosch Gmbh Vormischender Gasbrenner

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB166554A (en) * 1920-07-17 1921-09-22 Erich Gruenbaum Improvements in heating burners
DE401837C (de) * 1923-04-17 1924-09-09 Si Da Deutsche Gasgluehlicht I Heizbrenner
US3322179A (en) 1963-04-09 1967-05-30 Paul H Goodell Fuel burner having porous matrix
FR2057802A5 (de) * 1969-08-07 1971-05-21 Cav Ltd
US3947233A (en) 1971-04-26 1976-03-30 C. A. Sundberg Ab Free-burning equipment
JPS5442044A (en) * 1977-09-07 1979-04-03 Matsushita Electric Ind Co Ltd Cap for gas burner
DE8807395U1 (de) * 1987-06-12 1988-07-21 Joh. Vaillant Gmbh U. Co, 5630 Remscheid, De
DE9201313U1 (de) * 1992-02-04 1992-03-26 Hoval Interliz Ag, Vaduz-Neugut, Li
US5147201A (en) * 1990-11-19 1992-09-15 Institute Of Gas Technology Ultra-low pollutant emissions radiant gas burner with stabilized porous-phase combustion
EP0542074A2 (de) * 1991-11-11 1993-05-19 Lüdi, Roger Flammenhalter für Strahlungsbrenner
US5591095A (en) 1996-02-06 1997-01-07 Wu; Chia-Long Chain for a bicycle with derailleur

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB166554A (en) * 1920-07-17 1921-09-22 Erich Gruenbaum Improvements in heating burners
DE401837C (de) * 1923-04-17 1924-09-09 Si Da Deutsche Gasgluehlicht I Heizbrenner
US3322179A (en) 1963-04-09 1967-05-30 Paul H Goodell Fuel burner having porous matrix
FR2057802A5 (de) * 1969-08-07 1971-05-21 Cav Ltd
US3947233A (en) 1971-04-26 1976-03-30 C. A. Sundberg Ab Free-burning equipment
JPS5442044A (en) * 1977-09-07 1979-04-03 Matsushita Electric Ind Co Ltd Cap for gas burner
DE8807395U1 (de) * 1987-06-12 1988-07-21 Joh. Vaillant Gmbh U. Co, 5630 Remscheid, De
US5147201A (en) * 1990-11-19 1992-09-15 Institute Of Gas Technology Ultra-low pollutant emissions radiant gas burner with stabilized porous-phase combustion
EP0542074A2 (de) * 1991-11-11 1993-05-19 Lüdi, Roger Flammenhalter für Strahlungsbrenner
DE9201313U1 (de) * 1992-02-04 1992-03-26 Hoval Interliz Ag, Vaduz-Neugut, Li
US5591095A (en) 1996-02-06 1997-01-07 Wu; Chia-Long Chain for a bicycle with derailleur

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 003, no. 065 (M - 061) 6 June 1979 (1979-06-06) *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1731836A1 (de) * 2005-06-08 2006-12-13 Robert Bosch Gmbh Vormischender Gasbrenner

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