EP0890793A1 - Regelung von Brennstoffzufuhr für ein Heizgerät - Google Patents

Regelung von Brennstoffzufuhr für ein Heizgerät Download PDF

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Publication number
EP0890793A1
EP0890793A1 EP98202331A EP98202331A EP0890793A1 EP 0890793 A1 EP0890793 A1 EP 0890793A1 EP 98202331 A EP98202331 A EP 98202331A EP 98202331 A EP98202331 A EP 98202331A EP 0890793 A1 EP0890793 A1 EP 0890793A1
Authority
EP
European Patent Office
Prior art keywords
valve
air
sluice
air passage
downstream
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Withdrawn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
EP98202331A
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English (en)
French (fr)
Inventor
Johannes Albertus Hendrikus Willemsen
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.)
Heatex BV
Original Assignee
METAAL VRIES BV
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 METAAL VRIES BV filed Critical METAAL VRIES BV
Publication of EP0890793A1 publication Critical patent/EP0890793A1/de
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N3/00—Regulating air supply or draught
    • F23N3/02—Regulating draught by direct pressure operation of single valves or dampers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/02—Regulating fuel supply conjointly with air supply
    • F23N1/027—Regulating fuel supply conjointly with air supply using mechanical means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • F23N5/188—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using mechanical means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/14—Fuel valves electromagnetically operated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/16—Fuel valves variable flow or proportional valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/18—Groups of two or more valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/20—Membrane valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2241/00—Applications
    • F23N2241/06—Space-heating and heating water

Definitions

  • the invention relates to an assembly for controlling fuel supply according to the preamble of claim 1, and to a heating apparatus according to the preamble of claim 8.
  • Such assembly and such heating apparatus are known from DE-U-295 04 705.
  • De feed of air and fuel required for combustion are proportionally controllable for adapting the power of the apparatus to the heat delivery needed.
  • the valve which forms part of the sluice for generating a reduced pressure on the basis of which the fuel metering can be controlled is coupled to a temperature-dependent setting member for operating the valve depending on a detected temperature. This enables influencing the air supply depending on the temperature-dependent density of the air.
  • Drawbacks of such assembly and such heating apparatus are that it has a relatively limited power range and that when the fan is switched off, a thermal draft is created, causing the loss of heat present in the system.
  • DE-A-24 03 083 discloses an apparatus for controlling the air/fuel ratio for a burner, wherein an adjustable throttle valve is arranged in the air supply, which throttle valve is coupled to a control valve for controlling the supply of fuel depending on the set position of that throttle valve.
  • a fan with a suitable characteristic is used or a second throttle valve is provided downstream of the first throttle valve, which second throttle valve, in response to a deviation from the measured pressure drop over the first throttle valve, is set such that the pressure drop over the first throttle valve is always constant.
  • the second throttle valve closes according as the pressure drop over the first throttle valve is greater, and opens if the pressure drop falls out, for instance because the fan is switched off.
  • a drawback of this apparatus is that either the actual pressure drop over the throttle valve is not known, because it is not measured, or a separate, second throttle valve is required for readjusting the pressure drop over the first throttle valve, which has a cost-increasing effect and causes additional air resistance. Further, no valve is present which closes automatically if the fan switches off, and the power range is limited and the throttling losses at low powers are relatively high, because in each case, at least approximately the same pressure drop prevails over the adjustable throttle valve.
  • EP-A-0 050 506 a burner is described whose air supply comprises a valve operated depending on the relationship between the pressure directly downstream of that valve and the pressure downstream of the burner in order to keep the balance between supply and discharge pressure constant. In response to thermal draft when the burner is switched off, the valve closes and thus prevents heat losses. However, this valve operation does not provide the increase of the power range within which the burner can operate with a sufficiently accurately controlled air/fuel ratio.
  • valves for use in a suction channel of a combustion installation which open in response to a pressure drop over the valve and close in response to a fall of the pressure drop below a specific value.
  • valves form an extra provision which has a cost-increasing effect and increase the air resistance in the supply pipe.
  • the object of the invention is to increase the power range of an apparatus having a burner and a fan for the supply of combustion air, and to limit heat losses when the fan is switched off, without the addition of separate valves.
  • this object is attained by designing an assembly for controlling the supply of fuel as indicated in the characterizing part of claim 1, or by designing a heating apparatus as indicated in the characterizing part of claim 8.
  • valve which forms part of or constitutes the sluice, for limiting the air passage in response to the fall of a pressure drop over that valve, heat losses caused by thermal draft can be prevented without the addition of a separate valve for this purpose and the attendant costs and increase of the air resistance, because the valve is integrated into a sluice which also serves to create a pressure drop which is used as input variable for metering the fuel. Further, due to the valve which in response to the decrease of the pressure drop limits the air passage, the air flow rate at a given minimal, reliably measurable pressure drop over the valve is reduced, as a result of which the power range within which fuel can be metered sufficiently accurately is extended at the lower end. The minimal heat delivery that can be effected by the heating apparatus without intermittently switching off is thereby reduced.
  • the heating apparatus shown fully and partially in Figs. 1-4 is built up from an air supply channel 1, a gas supply channel 2 constituting the fuel supply channel, a fan 3, a mixing nose 4, a burner 5 and a discharge channel 6, a downstream portion of which extends coaxially in the air supply channel 1.
  • Heating apparatus of such construction are known per se and generally commercially available. For this reason, the general design of the heating apparatus is described only succinctly. In operation, the flow direction of air and different gases is as indicated by arrows 7-14.
  • a sluice 15 Located in the air channel 1 is a sluice 15 and the apparatus comprises a pressure transmission line 16 via which line a fuel metering member in the form of a gas control unit 18 communicates with portions of the air supply channel 1 upstream of the sluice 15.
  • the gas supply channel 2 ending downstream of the sluice 15 also constitutes the pressure transmission line via which the gas control unit 18 communicates with portions of the air supply channel 1 downstream of the sluice 15 for transmitting the pressure in that portion of the air supply channel. It is true that during the delivery of gas, pressure prevailing directly downstream of the gas control unit 18 in the gas supply channel 2 is to a slight degree partially influenced by the inflow of gas, but this can be taken into account during the adjustment of the gas control unit 18.
  • the gas control unit it is also possible to cause the gas control unit to meter depending on the pressure drop between other areas, for instance directly on either side of the sluice.
  • the pressure drop between areas at a greater distance on either side of the valve or exclusively the reduced pressure downstream of the valve, as basis for the fuel metering.
  • the difference between the pressure directly upstream of the valve and the pressure at a greater distance downstream of the valve or vice versa can also serve as input variable.
  • the pressure transmission line 16 and a pressure transmission channel 19 for transmitting the pressure in the gas supply channel 2 upstream of a metering valve 28 of the gas control unit 18 cooperate for passing gas via the metering valve 28, depending on the pressure drop over the sluice 15.
  • the gas control unit comprises a primary on-off valve 29 which is urged into a closed rest position by a spring 30. Via a bell crank 31, the valve is coupled to an electromagnet 32.
  • the metering valve 28 located downstream of the primary on-off valve 29 in the gas supply channel 2 is likewise urged into a closed rest position by a spring 33 bearing against a face 34 of a guide 35.
  • the valve 28 has a valve disk 36 which, in closed condition, butts against a valve seat 37. From the valve disk 36, a valve rod 38 extends to an operating disk 39 supported by a diaphragm 40.
  • the diaphragm 40 closes a space 41 from the gas supply channel 2. This space 41 communicates with a chamber 42 which, via the pressure transmission channel 19, communicates with a portion of the gas supply channel 2 upstream of the metering valve 28.
  • the secondary on-off valve 43 is connected, via a bell crank 44, to an electromagnet 46. Integrated into the electromagnet 46 is a spring 47 which keeps the valve 43 closed when the electromagnet 46 is not energized.
  • the chamber 42 further communicates with the portion of the gas supply channel 2 downstream of the metering valve 28 via an aeration opening 48 and via a compensation channel 49, closable by a settable diaphragm valve 50.
  • the fan 11 When the heating apparatus is controlled for delivering heat, the fan 11 is set in motion and the electromagnets 32, 46 are activated for opening the primary and secondary on-off valves 29, 43 against the pressure of the springs 30, 47. Now, the space 41 is pressurized via the channel 19 and the chamber 42. Since the operating disk 39 has a larger surface area than the surface area enclosed by the valve seat 37 of the metering valve 28, a net force is hereby exerted on the metering valve 28 in opening direction, which force depends on the excess pressure in the space 41 and the reduced pressure in the gas supply channel 2 downstream of the metering valve 28. The stronger the reduced pressure, the more gas is passed.
  • excess pressure can be blown off via the diaphragm valve 50 from the chamber 42 to a portion of the gas supply channel 2 downstream of the metering valve 28, as a result of which the metering valve 28 closes slightly and the gas metering is adjusted.
  • the operation of the diaphragm valve 50 can be adjusted with an adjusting screw 52.
  • gas is passed by the gas control unit 18 in a metered manner depending on, inter alia, the pressure drop over the sluice 15.
  • the burner 5 communicates with the air supply channel 1 and with the gas supply channel 2 and is located downstream of the two channels 1, 2 and a mixing nose 4, so that in operation, a gas/air mixture to be combusted reaches the burner 5 and is processed by the burner 5.
  • the discharge channel 6 for discharging gases resulting from combustion communicates with the burner 5 and is located downstream thereof.
  • the first portion of the discharge channel 6 is designed as a part of a heat exchanger, not shown.
  • a fan 3 for generating and maintaining an air flow through the air supply channel 1, the mixing nose 4, the burner 5 and the discharge channel 6.
  • the fan 3 is controllable by a control unit, not shown.
  • the burner 5 communicates with the environment exclusively via the supply and discharge channels 1 and 2.
  • the burner 5 communicates with the gas supply channel 2 for feeding gas from a gas provision, such as a gas tank or a branch from a gas distribution network.
  • the sluice 15 is arranged as a valve for closing off the air supply channel 1.
  • valve 15 In operation, the valve 15 is closed as long as the fan 3 is switched off and, accordingly, stands still or at least does not maintain an air flow in the direction of the arrows 7-14. As soon as the fan 3 is switched on, a pressure drop over the valve 15 is created, in response to which the valve 15 opens and air is fed as indicated by the arrows 7, 8, 11. The generated pressure drop over the valve 15 is transmitted to the gas control unit 18 which, depending thereon, passes gas to the air supply channel 1.
  • the fed air and the fed gas are mixed in the mixing nose 4 to form a highly homogeneous mixture having - owing to the accurately metered gas delivery by the gas control unit - the proper mixing ratio, resulting in a combustion with very slight CO, NO and No x emissions.
  • the combustion gases are discharged via the discharge channel 6 (arrows 12, 13, 14), and in the portion of the discharge channel 6 extending coaxially with the air supply channel 1, residual heat is transferred to air fed via the air channel 1.
  • valve 15 When no heat is demanded anymore and the fan 3 is switched off, the pressure drop over the valve 15 falls out at least substantially. In response thereto, the valve 15 closes again. The closing of the valve 15 prevents the possible formation of a substantial air flow through the heating apparatus by thermal draft caused by hot air in the heating apparatus (or by whatever cause), whereby heat is given up from that apparatus to the environment and the apparatus and a medium or product to be heated present therein are cooled.
  • a separate sluice can be saved and extra air resistance that would be caused by a valve supplementing the sluice is avoided.
  • the valve could be actively operated in response to the detected pressure drop.
  • the valve 15 shown is of passive construction and is itself reactive for closing off the air passage if the pressure drop in flow direction drops below a specific value. Hence, no active drive of the valve is required, which limits the manufacturing costs and chances of failure. If the thermal draft occurring after the fan has been switched off is in the same direction as the flow direction of air when the fan is switched on, it is important that the closing force of the valve is greater than the pressure difference, caused by the thermal draft, between areas on either side of the valve.
  • the valve shown in Figs. 3 and 4 comprises a spring 20 urging a valve body 21 springily towards its closed position if the valve 15 is in open condition.
  • a spring offers the advantage that the construction can be light, that there is more freedom as regards the opening characteristic of the valve and that adjusting possibilities can readily be provided.
  • valve 15 As regards the construction of the valve according to Figs. 1, 3 and 4, it can furthermore be observed that it further contains a support structure 22 with a guide bore 23, through which guide bore a support pin 24 extends, which support pin carries a support 25 for the spring 20 and which is adjustable relative to the support structure and a valve seat 27 by means of an adjusting ring 26.
  • the valve 15 In Fig. 1, the valve 15 is shown in open condition and in Fig. 2, the valve 15 is shown in closed condition.
  • the spring 20 In the valve 15 shown, the spring 20 is located downstream of the valve body 21, but the spring 20 may also be located upstream of the valve body 21.
  • the valve 15 opens further. Releasing said air passage to a greater or lesser degree, depending on the pressure drop, offers the advantage that at low air flow rates, greater reduced pressures occur which can be detected more accurately. Further, at a given band width within which pressures can be measured sufficiently accurately or can be used for metering gas or another fuel, the air flow rate can be controlled within a greater band width. This enables having the heating apparatus operate at a lower minimum power.
  • the relationship between the pressure drop over the valve and the flow rate of the passing air can be influenced particularly aptly if the position of the valve adjusts itself stepwise. Particularly advantageous is a stepless adjustment of the valve position, because in that case, in addition to scanning a pressure in the area of or downstream of the sluice, no provisions for scanning the momentary position of the valve are needed.
  • valve 15 is adjustable for adjusting the relationship between pressure drop and valve position, manufacturing tolerances can readily be taken up and the valve can moreover be used for adjusting the air/fuel ratio, for instance for adapting it to different fuels having different calorific values.
  • the scanning means for scanning a pressure drop over the sluice are designed as a scanner for scanning the position of said valve.
  • the degree to which the valve opens in response to the strength of the air flow and, accordingly, the pressure exerted thereon is then used as measure for the amount of passing air, for instance in the form of a potentiometer. Pressure sensors can then be left out, if necessary.
  • valve 15 can close off the air channel 1 completely, it is also possible to construct the valve such that the air channel can be closed off only partially or substantially. Although in that case, no total blocking of thermal draft is obtained, it can in fact be partially or largely limited, which also results in a limitation, albeit a slighter one, of heat losses.
  • a non-complete closure of the air passage is advantageous for a reliable operation of the heating apparatus at very low air flow rates.
  • the passage for passing air if the valve 15 is closed may for instance be designed in the form of a bypass which, in turn, may or may not also comprise a valve, preferably a more sensitive one.
  • the passage may also be designed in the form of an opening between the valve body in closed condition and the valve seat. The valve can then be of such design that it remains closed if the apparatus operates in a lowest position or a lowest number of positions and opens only when the speed of the fan, and accordingly the generated reduced pressure, exceeds a specific limit.
  • Figs. 5 and 6 show an alternative construction of the valve integrated with the sluice, indicated by reference numeral 45.
  • the support structure for guiding and supporting the support pin 54 is integrated with the valve seat to form a plate 57 having bores 58, closable by the valve body 51.
  • the support structure is integrated with the valve seat to form a plate-shaped support 87 having openings 88.
  • the valve body also forms the springy member, in that the valve body is designed as a flexible diaphragm 81, bendable back and forth in the direction indicated by arrows 89 between a position shown in full lines and a position indicated in broken lines. In the open position, air can pass as indicated by arrows 68.
  • the diaphragm is held in position against the plate-shaped support 87 by a fastener 90.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Regulation And Control Of Combustion (AREA)
EP98202331A 1997-07-11 1998-07-09 Regelung von Brennstoffzufuhr für ein Heizgerät Withdrawn EP0890793A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1006559 1997-07-11
NL1006559A NL1006559C2 (nl) 1997-07-11 1997-07-11 Regeling van brandstof-toevoer aan een verwarmingstoestel.

Publications (1)

Publication Number Publication Date
EP0890793A1 true EP0890793A1 (de) 1999-01-13

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EP98202331A Withdrawn EP0890793A1 (de) 1997-07-11 1998-07-09 Regelung von Brennstoffzufuhr für ein Heizgerät

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EP (1) EP0890793A1 (de)
NL (1) NL1006559C2 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170038067A1 (en) * 2013-01-16 2017-02-09 A. O. Smith Corporation Modulating Burner

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1310619A (fr) * 1961-10-17 1962-11-30 Gen Thermique Procedes Brola Dispositif de régulation et de sécurité pour brûleurs à gaz
DE2403083A1 (de) * 1974-01-23 1975-07-31 Ennking Heinz Dr Rer Nat Verfahren und vorrichtung zum kontinuierlichen betrieb von feuerungsanlagen mit beliebigem fluessigem oder gasfoermigem brennstoff
EP0050506A2 (de) * 1980-10-20 1982-04-28 Esso Société Anonyme Française Brenner mit Luftregeleinrichtung
US4353349A (en) * 1980-12-16 1982-10-12 Bormida Jr John Retrofittable energy conserving damper
JPH02169920A (ja) * 1988-12-22 1990-06-29 Rinnai Corp 強制送風式燃焼装置
EP0505714A2 (de) * 1991-03-26 1992-09-30 Robert Bosch Gmbh Regelvorrichtung für Gasbrenner mit einem Gebläse zum Zuführen von Verbrennungsluft
JPH0618020A (ja) * 1992-06-30 1994-01-25 Noritz Corp 燃焼装置
DE9401894U1 (de) * 1993-02-08 1994-03-24 Joh. Vaillant Gmbh U. Co, 42859 Remscheid Heizgerät
DE29504705U1 (de) * 1995-03-24 1996-07-25 Robert Bosch Gmbh, 70469 Stuttgart Regelvorrichtung für einen Brenner mit einem Gebläse für die Verbrennungsluft

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1310619A (fr) * 1961-10-17 1962-11-30 Gen Thermique Procedes Brola Dispositif de régulation et de sécurité pour brûleurs à gaz
DE2403083A1 (de) * 1974-01-23 1975-07-31 Ennking Heinz Dr Rer Nat Verfahren und vorrichtung zum kontinuierlichen betrieb von feuerungsanlagen mit beliebigem fluessigem oder gasfoermigem brennstoff
EP0050506A2 (de) * 1980-10-20 1982-04-28 Esso Société Anonyme Française Brenner mit Luftregeleinrichtung
US4353349A (en) * 1980-12-16 1982-10-12 Bormida Jr John Retrofittable energy conserving damper
JPH02169920A (ja) * 1988-12-22 1990-06-29 Rinnai Corp 強制送風式燃焼装置
EP0505714A2 (de) * 1991-03-26 1992-09-30 Robert Bosch Gmbh Regelvorrichtung für Gasbrenner mit einem Gebläse zum Zuführen von Verbrennungsluft
JPH0618020A (ja) * 1992-06-30 1994-01-25 Noritz Corp 燃焼装置
DE9401894U1 (de) * 1993-02-08 1994-03-24 Joh. Vaillant Gmbh U. Co, 42859 Remscheid Heizgerät
DE29504705U1 (de) * 1995-03-24 1996-07-25 Robert Bosch Gmbh, 70469 Stuttgart Regelvorrichtung für einen Brenner mit einem Gebläse für die Verbrennungsluft

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 014, no. 432 (M - 1026) 17 September 1990 (1990-09-17) *
PATENT ABSTRACTS OF JAPAN vol. 018, no. 227 (M - 1597) 25 April 1994 (1994-04-25) *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170038067A1 (en) * 2013-01-16 2017-02-09 A. O. Smith Corporation Modulating Burner
US10208953B2 (en) * 2013-01-16 2019-02-19 A. O. Smith Corporation Modulating burner

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