WO2002029319A1 - An improved air-gas mixer device - Google Patents

An improved air-gas mixer device Download PDF

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Publication number
WO2002029319A1
WO2002029319A1 PCT/EP2001/001757 EP0101757W WO0229319A1 WO 2002029319 A1 WO2002029319 A1 WO 2002029319A1 EP 0101757 W EP0101757 W EP 0101757W WO 0229319 A1 WO0229319 A1 WO 0229319A1
Authority
WO
WIPO (PCT)
Prior art keywords
gas
venturi duct
duct
air
venturi
Prior art date
Application number
PCT/EP2001/001757
Other languages
French (fr)
Inventor
Raffaele Zocchi
Filiberto Rimondo
Salvatore Pappalardo
Original Assignee
Sit La Precisa S.P.A.
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
Priority to ITPD20000227 priority Critical patent/IT1315743B1/en
Priority to ITPD2000A000227 priority
Application filed by Sit La Precisa S.P.A. filed Critical Sit La Precisa S.P.A.
Publication of WO2002029319A1 publication Critical patent/WO2002029319A1/en

Links

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
    • F23D14/62Mixing devices; Mixing tubes
    • F23D14/64Mixing devices; Mixing tubes with injectors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23DBURNERS
    • F23D2900/00Special features of, or arrangements for burners using fluid fuels or solid fuels suspended in a carrier gas
    • F23D2900/14Special features of gas burners
    • F23D2900/14701Swirling means inside the mixing tube or chamber to improve premixing

Abstract

ABSTRACT An air-gas mixer device, in particular for gas burners, comprises a Venturi duct (2) inside which a portion (15) with a narrow cross-section is defined and outside which a gas-distribution chamber (17) is defined, as well as gas- intakes (21a-d, 22a-d) which are formed with an orientation having a predominant axial component in the Venturi duct and which open in the wall of the narrow-sectioned portion (15), between the gas-distribution chamber (17) and the interior of the Venturi duct (2). Upstream of the Venturi duct (2), with reference to the direction of the air-flow entering the duct, there is a member (23) with stationary blading for imparting a component of rotational motion to the air entering the Venturi duct (2).

Description

An improved air-gas mixer device Technical field
The present invention relates to an air-gas mixer device according to the preamble to the main claim. Technological background
As is well known, devices of this type are used in apparatus with gas burners, in particular, with forced ventilation, and generally comprise a valve unit for delivering the gas-flow into the smaller-sectioned region of a Venturi duct at '" a. pressure which is controlled in i. dependence on the pressure detected upstream of the Venturi duct. The degree of homogeneity of the air-gas mixture is improved by means of a fan which is normally positioned downstream of the Venturi duct . A mixer device having the above-mentioned characteristics is described, for example, in Italian patent No. 1288006. This device has the particular characteristic of enabling adequate homogeneity of the air-gas mixture to be achieved by the admission of the gas-flow to the Venturi duct in a predominantly axial direction, along the duct. Description of the invention
A main object of the present invention is to provide an air-gas mixer of the above-mentioned type which is designed structurally and functionally to improve the accuracy of the metering of the fuel gas in the air-gas mixture delivered to the burner.
Another object is to provide an air-gas mixer which can extend the range of modulation of the flow-rate delivered.
These and other objects which will be explained below are achieved by the invention by means of an air-gas mixer device formed in accordance with the appended claims . Brief description of the drawings
The characteristics and the advantages of the invention will become clearer from the detailed description of a preferred embodiment thereof, described below by way of non- limiting example with reference to the appended drawings, in which:
- Figure 1 is a perspective view of an air-gas mixer device according to the present invention,
- Figure 2 is a longitudinal section through the mixer device of Figure 1, part of which is shown only schematically,
- Figure 3 is a section taken on the line III-III of Figure 2, and
- Figure 4 is a perspective view of a detail of the mixer device of the preceding drawings, on an enlarged scale.
Preferred embodiment of the invention
With reference initially to Figure 1, an air-gas mixer device, in particular for supplying a forced-ventilation gas burner (not shown) and formed in accordance with the present invention, is generally indicated 1.
The device 1 comprises a Venturi duct 2 of axis X, positioned coaxially inside a tubular duct 3 having opposed axial ends 3a, 3b.
The air-flow passing through the tubular duct 3 is directed axially relative to the duct, in the direction indicated by the arrow F of Figure 2, from the end 3a towards the opposite end 3b.
The mixer device 1 also comprises a valve unit 6, shown schematically in Figure 2, for delivering gas into the Venturi duct 2 at a pressure which is controlled in dependence on the air pressure detected inside the tubular duct 3 upstream of the Venturi duct 2. The reduced pressure in the constriction of the Venturi duct 2 induces a corresponding pressure of the gas supplied through a hole 11 in the tubular duct 3. The arrow 9 indicates the admission of gas from the external supply mains to the valve unit 6, and the arrow 10 indicates the controlled delivery of gas to the hole 11 by the valve unit 6.
The Venturi duct 2, which is inside and coaxial with the tubular duct 3, has a double-cone configuration defined by an inner wall 2a of a hollow body 12 which is engaged in the tubular duct 3 in a leaktight manner and abuts a shoulder 3c on the side facing towards the end 3b.
The hollow body 12 comprises a first, converging, inlet portion 14, a second, intermediate portion 15 with a narrow cross-section, and a third, diverging, outlet portion 16. As is well known, the narrow cross-sectioned intermediate portion 15 is the portion in which the gas-flow passing through the Venturi duct has the fastest speed and the lowest pressure. In the region of the second and third portions 15, 16, the hollow body 12 has an external constriction defining, with the surface of the tubular duct 3, a gas-distribution chamber 17 which is in communication with the inlet hole 11. In the region of the narrow cross-sectioned portion 15, the hollow body 12 has a series of four ribs 18a, 18b, 18c, 18d defining a corresponding number of recesses 19a, 19b, 19c, 19d in the bases of which respective shoulders, indicated 20a, 20b, 20c, 20d are formed. The shoulders 20a, 20b, 20c, 20d are arranged substantially at right angles to the axis X of the Venturi duct 2 at the downstream end (with reference to the direction of the arrow F) of the narrow- sectioned portion 15.
For each shoulder 20a-d, starting from the wall of the shoulder 20a-d, the inner wall of the hollow body 12, that is, the wall defining the Venturi duct 2, has a respective depression 21a-d with a cylindrical surface and an axis substantially parallel to the axis X of the Venturi duct 2. Owing to the taper of the third portion 16 of the Venturi duct, the depressions 21a-d have cross-sections which decrease progressively in the direction of the flow F.
A slot 22a-d opening in the respective shoulder 20a-d is formed at the base of each depression 21a-d, owing to its intersection with the corresponding recess 19a-d. The slots 22a-d define, with the respective depressions 21a-d, a corresponding number of intakes for admitting gas into the Venturi duct 2 from the distribution chamber 17. The gas- intakes open into the Venturi duct 2 in an equiangularly- spaced arrangement .
The slots 22a-d lie in a plane perpendicular to the axis X of the Venturi duct 2 and, owing to the positions of the depressions 21a-d, cause the orientations of the gas- intakes to have a predominant axial component .
According to a main characteristic of the device according to the invention, a distributor member, generally indicated 23, with stationary blading, is positioned upstream of the Venturi duct 2 in the region of the end 3a. The member 23 is mounted coaxially relative to the tubular duct and comprises a hub 24 from which a plurality of blades, all indicated 25, extend radially, the blades 25 having a predetermined twist, and being fixed to a skirt 26 at their ends remote from the hub 24. The blades 25 are stationary and have a curvature of their twist profiles such as to impart a rotational component to the air-flow entering the Venturi duct 2. The rotational kinetic component imparted to the air-flow is such as to induce a greater reduction in pressure at the narrow-sectioned point 15 of the Venturi duct 2 where the injection of gas takes place, achieving greater accuracy in the regulation of the flow-rate of fuel gas injected through the slots 22a-d. The greater accuracy in the admission of the gas-flow also enables the effective range of modulation of the flow-rate of the air-gas mixture delivered by the device to be increased.
It should be noted that tests carried out by the Applicant have shown that the provision of distributor members with stationary blading in a mixer device with axial injection of gas into the Venturi duct leads to greater accuracy in the regulation of the metering of the gas and to a wider range of modulation of the flow-rate in comparison with conventional mixers with substantially radial admission of the gas to the Venturi duct .
It has also been noted that the rotational kinetic component imparted to the gas-flow entering the Venturi duct enables the detachment of the flow from the wall of the diverging outlet portion 16 to be delayed as far as possible or even completely prevented, advantageously reducing pressure losses in this region.
According to a further characteristic of the invention, a radial fan 28 is connected with its intake opening 28a at the outlet opening of the diverging portion 16 of the Venturi duct 2. If the direction of rotation of the fan 28 is selected so as to be the same as the direction of the rotational component imparted to the flow of the air-gas mixture, the latter will enter the fan 28 with very low losses. If, on the other hand, the direction of rotation of the fan and of the rotational component of the flow are not the same, a greater amplification of the pressure signal controlling the valve unit is achieved in the region in which the gas is injected into the Venturi duct. The invention thus ' achieves the objects proposed, affording the advantages mentioned above with reference to the prior art cited.

Claims

Claims
1. An air-gas mixer device, in particular for gas burners, comprising a Venturi duct (2) inside which a portion (15) with a narrow cross-section is defined and outside which a gas-distribution chamber (17) is" defined, and gas-intakes (21a-d, 22a-d) which are formed with an orientation having a predominant axial component in the Venturi duct (2) and which open in the wall of the narrow- sectioned portion (15) , between the gas-distribution chamber (17) and the interior of the Venturi duct (2) , characterized in that the device comprises, upstream of the Venturi duct, with reference to the direction of the air-flow entering the duct, a member (23) with stationary blading for imparting a component of rotational motion to the air entering the Venturi duct (2) .
2. A device according to Claim 1 in which the blading is arranged coaxially with the Venturi duct (2) .
3. A device according to Claim 1 or Claim 2 in which the member (23) with stationary blading comprises a hub (24) from which a plurality of blades (25) with preselected twist profiles extend substantially radially.
4. A device according to Claim 3 in which the blades (25) extend from the hub (24) in uniformly-spaced angular positions.
5. A device according to Claim 3 or Claim 4 in which the blades (25) are connected, at their ends remote from the hub (24) , to a skirt (26) which can be housed in a tubular portion of the device.
6. A device according to one or more of the preceding claims in which the blading (25) is positioned upstream of an inlet portion (14) of the Venturi duct (2) which converges into the narrow-sectioned portion (15) .
7. A device according to one or more of the preceding claims, comprising a fan (28) positioned downstream of the Venturi duct (2) with reference to the direction of the airflow.
8. A device according to Claim 7 in which the fan (28) is a radial fan.
9. A device according to Claim 7 or Claim 8 in which the fan (28) comprises an intake opening (28a) connected to an outlet portion (16) of the Venturi duct (2) which diverges from the narrow sectioned portion (15) .
PCT/EP2001/001757 2000-10-03 2001-02-16 An improved air-gas mixer device WO2002029319A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
ITPD20000227 IT1315743B1 (en) 2000-10-03 2000-10-03 Improved air-gas mixing device.
ITPD2000A000227 2000-10-03

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AU4062601A AU4062601A (en) 2000-10-03 2001-02-16 An improved air-gas mixer device

Publications (1)

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WO2002029319A1 true WO2002029319A1 (en) 2002-04-11

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AU (1) AU4062601A (en)
IT (1) IT1315743B1 (en)
WO (1) WO2002029319A1 (en)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004054796B3 (en) * 2004-11-12 2006-03-16 Robert Bosch Gmbh Mixer unit e.g. for gas premix burner, has combustion air channel which moves air downstream into blower for promotion of gas air mixture to burner surface, as well as to attached gas armature
EP1912021A1 (en) 2006-10-06 2008-04-16 Jakob Hermann Combustion chamber equipped with a burner
WO2009087041A3 (en) * 2008-01-08 2009-09-17 Ln 2 S.R.L. A Socio Unico Inlet device for an air/gas flow in a fan unit, particularly for gas burners with pre-mixing
FR2936040A1 (en) * 2008-09-18 2010-03-19 Guillot Ind Sa BOILER MIXER
ITPD20080324A1 (en) * 2008-11-07 2010-05-08 Sit La Precisa S P A Con Socio Uni Co Gas burner appliance with pre-mixing
DE102009024269A1 (en) * 2009-06-05 2010-12-09 Honeywell Technologies S.A.R.L. Mixing device for a gas burner
DE102010048626A1 (en) * 2010-10-15 2012-04-19 Friedrich Boysen Gmbh & Co. Kg Mixing device for mixing two fluid streams, particularly for exhaust system of internal combustion engine, comprises primary pipeline for primary fluid stream, and secondary pipeline for secondary fluid stream
WO2012123207A2 (en) 2011-03-15 2012-09-20 Ebm-Papst Landshut Gmbh Mixing device for mixing combustion air and gas for a gas appliance
WO2012006166A3 (en) * 2010-06-29 2012-12-06 A.O. Smith Corporation Blower assembly with venturi -mixer for use with gas powered appliance
JP2015515598A (en) * 2013-03-04 2015-05-28 ケム ソク ソン, Pan metal fiber gas burner
CN104728842A (en) * 2015-02-06 2015-06-24 宁波市甬深电器有限公司 Forced full-premixing fuel gas combustion device enabling fuel gas to be completely combusted
JP2015230113A (en) * 2014-06-04 2015-12-21 リンナイ株式会社 Premixing device
DE102016113588A1 (en) * 2016-07-22 2018-01-25 Ebm-Papst Landshut Gmbh Gas-air mixing device

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0674423A (en) * 1992-08-26 1994-03-15 Miura Kenkyusho:Kk Apparatus for mixing air and fuel gas
EP0669497A2 (en) * 1994-02-26 1995-08-30 H KRANTZ-TKT GmbH Device for incinerating oxidizable noxions compounds
EP0846916A2 (en) * 1996-12-06 1998-06-10 SIT LA PRECISA S.r.l. An air-gas mixing device particularly for gas burners with forced ventilation
EP0896191A2 (en) * 1997-08-05 1999-02-10 KARL DUNGS GMBH & CO. Fuel gas admission device for a premix burner
EP0896192A2 (en) * 1997-08-05 1999-02-10 KARL DUNGS GMBH & CO. Fuel gas admission device for a premix burner

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0674423A (en) * 1992-08-26 1994-03-15 Miura Kenkyusho:Kk Apparatus for mixing air and fuel gas
EP0669497A2 (en) * 1994-02-26 1995-08-30 H KRANTZ-TKT GmbH Device for incinerating oxidizable noxions compounds
EP0846916A2 (en) * 1996-12-06 1998-06-10 SIT LA PRECISA S.r.l. An air-gas mixing device particularly for gas burners with forced ventilation
EP0896191A2 (en) * 1997-08-05 1999-02-10 KARL DUNGS GMBH & CO. Fuel gas admission device for a premix burner
EP0896192A2 (en) * 1997-08-05 1999-02-10 KARL DUNGS GMBH & CO. Fuel gas admission device for a premix burner

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 018, no. 325 (M - 1625) 21 June 1994 (1994-06-21) *

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004054796B3 (en) * 2004-11-12 2006-03-16 Robert Bosch Gmbh Mixer unit e.g. for gas premix burner, has combustion air channel which moves air downstream into blower for promotion of gas air mixture to burner surface, as well as to attached gas armature
EP1657489A1 (en) 2004-11-12 2006-05-17 Robert Bosch Gmbh Mixing device for a premix burner
EP1912021A1 (en) 2006-10-06 2008-04-16 Jakob Hermann Combustion chamber equipped with a burner
EP1912021B1 (en) * 2006-10-06 2013-03-13 Jakob Hermann Combustion chamber equipped with a burner
WO2009087041A3 (en) * 2008-01-08 2009-09-17 Ln 2 S.R.L. A Socio Unico Inlet device for an air/gas flow in a fan unit, particularly for gas burners with pre-mixing
EP2166285A1 (en) 2008-09-18 2010-03-24 Guillot Industrie Mischer für Kessel
FR2936040A1 (en) * 2008-09-18 2010-03-19 Guillot Ind Sa BOILER MIXER
ITPD20080324A1 (en) * 2008-11-07 2010-05-08 Sit La Precisa S P A Con Socio Uni Co Gas burner appliance with pre-mixing
WO2010052746A2 (en) * 2008-11-07 2010-05-14 Sit La Precisa S.P.A. Con Socio Unico A gas burner apparatus with pre-mixing
RU2511820C2 (en) * 2008-11-07 2014-04-10 СИТ ЛА ПРЕЧИЗА С.П.А. кон сочио унико Gas burner device with preliminary mixing
WO2010052746A3 (en) * 2008-11-07 2011-04-07 Sit La Precisa S.P.A. Con Socio Unico A gas burner apparatus with pre-mixing
DE102009024269A1 (en) * 2009-06-05 2010-12-09 Honeywell Technologies S.A.R.L. Mixing device for a gas burner
EP2258983A3 (en) * 2009-06-05 2014-09-03 Honeywell Technologies Sarl Mixing device for a gas burner
WO2012006166A3 (en) * 2010-06-29 2012-12-06 A.O. Smith Corporation Blower assembly with venturi -mixer for use with gas powered appliance
DE102010048626A1 (en) * 2010-10-15 2012-04-19 Friedrich Boysen Gmbh & Co. Kg Mixing device for mixing two fluid streams, particularly for exhaust system of internal combustion engine, comprises primary pipeline for primary fluid stream, and secondary pipeline for secondary fluid stream
WO2012123207A2 (en) 2011-03-15 2012-09-20 Ebm-Papst Landshut Gmbh Mixing device for mixing combustion air and gas for a gas appliance
DE102011014117A1 (en) 2011-03-15 2012-09-20 Ebm-Papst Landshut Gmbh Mixing device for mixing combustion air and gas for a gas appliance
JP2015515598A (en) * 2013-03-04 2015-05-28 ケム ソク ソン, Pan metal fiber gas burner
JP2015230113A (en) * 2014-06-04 2015-12-21 リンナイ株式会社 Premixing device
US10030868B2 (en) 2014-06-04 2018-07-24 Rinnai Corporation Premixing apparatus
CN104728842A (en) * 2015-02-06 2015-06-24 宁波市甬深电器有限公司 Forced full-premixing fuel gas combustion device enabling fuel gas to be completely combusted
DE102016113588A1 (en) * 2016-07-22 2018-01-25 Ebm-Papst Landshut Gmbh Gas-air mixing device
WO2018015130A1 (en) * 2016-07-22 2018-01-25 Ebm-Papst Landshut Gmbh Gas-air mixing device
EP3488148B1 (en) * 2016-07-22 2021-02-17 EBM-PAPST Landshut GmbH Gas-air mix device

Also Published As

Publication number Publication date
IT1315743B1 (en) 2003-03-18
ITPD20000227A1 (en) 2002-04-03
ITPD20000227D0 (en) 2000-10-03
AU4062601A (en) 2002-04-15

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