EP0757207B1 - Steuervorrichtung für katalytische Gasbrenner - Google Patents

Steuervorrichtung für katalytische Gasbrenner Download PDF

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Publication number
EP0757207B1
EP0757207B1 EP96109737A EP96109737A EP0757207B1 EP 0757207 B1 EP0757207 B1 EP 0757207B1 EP 96109737 A EP96109737 A EP 96109737A EP 96109737 A EP96109737 A EP 96109737A EP 0757207 B1 EP0757207 B1 EP 0757207B1
Authority
EP
European Patent Office
Prior art keywords
control arrangement
burner
temperature
catalytic
catalyst
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.)
Expired - Lifetime
Application number
EP96109737A
Other languages
English (en)
French (fr)
Other versions
EP0757207A1 (de
Inventor
Claudio Cenedese
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.)
Zeltron SpA
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Zeltron SpA
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 Zeltron SpA filed Critical Zeltron SpA
Publication of EP0757207A1 publication Critical patent/EP0757207A1/de
Application granted granted Critical
Publication of EP0757207B1 publication Critical patent/EP0757207B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • F23D14/18—Radiant burners using catalysis for flameless combustion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
    • F23N5/022—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/08—Measuring temperature
    • F23N2225/16—Measuring temperature burner temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2227/00—Ignition or checking
    • F23N2227/10—Sequential burner running
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2227/00—Ignition or checking
    • F23N2227/36—Spark ignition, e.g. by means of a high voltage
    • 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
    • F23N2237/00—Controlling
    • F23N2237/12—Controlling catalytic burners

Definitions

  • the present invention refers to an arrangement for controlling the operation of a catalytic burner adapted in particular for use in household-type appliances, and more generally also in commercial and industrial equipment or air-conditioning systems.
  • Catalytic gas combustion is generally known to consist in the oxidation of a fuel, such as for instance methane gas, with a combustion supporting agent, such as air, said oxidation being sustained at a low temperature (lower than approx. 1000°C) by an appropriate catalyst material which remains unaltered during the entire combustion process.
  • a fuel such as for instance methane gas
  • a combustion supporting agent such as air
  • an appropriate catalyst material which remains unaltered during the entire combustion process.
  • the most widely known and used catalysts are metals or metal compounds, such as oxides, ceramics and the like, based on chemical elements belonging to the group of precious metals, in particular platinum, palladium and rhodium.
  • Catalysts are usually supported by an inert material having a large surface area and ensuring conditions of great porosity, such as for instance alumina or wire gauze.
  • Catalytic burners in particular for domestic cooker applications, are described for instance in JP-A-62 266 317, US-A-3 067 811, US-A-4 189 294 and EP-A-0 469 251. Furthermore, catalytic combustion is getting a firm foothold in the automotive industry, where it is increasingly used in applications aimed at cutting emissions of noxious exhaust gases from internal combustion engines.
  • Combustion control systems of the closed-loop type for catalytic burners are known in connection with industrial equipment applications.
  • the heat output of the catalytic burner is controlled by adjusting the flow rate of the fuel gas through a manually operated valve or similar device.
  • the flow rate of the fuel gas which may for instance be LPG, is measured by an appropriate flow metering sensor.
  • the corresponding information received from such a sensor is used to calculate, through appropriate tables or mathematical functions, the actual amount of air needed to completely oxidize the amount of gas flowing through the metering sensor.
  • Such a computation may be performed by means of a series of functional blocks, which may for instance be provided on a board with an electronic microcontroller.
  • the air flow required to ensure complete combustion of the fuel gas is produced by a variable-speed fan which is controlled directly by the electronic microcontroller.
  • An air flow metering sensor located in correspondence of the delivery side of the fan measures the amount of air which is actually delivered by the fan and correspondingly drives the microcontroller so as to compensate for any possible variation in the flow rate.
  • a closed-loop control system acting on the delivery of the amount of air required for a correct combustion is in this way provided.
  • the fuel gas and the combustion air mix in correspondence of the burner, where they are burnt in the presence of the catalyst, which must anyway be preliminarily heated in view of enabling the catalytic reaction to be triggered.
  • a control system of the above described type would only be able to operate correctly if the quantities measured by both the gas flow-rate sensor and the air flow-rate sensor are not affected by errors and the fuel gas composition is rigorously constant. However, such conditions never occur in the usual practice. Furthermore, it is a largely known fact that inert substances are quite frequently introduced in gas utility lines in view of ensuring an adequate gas supply pressure in peak demand periods. All such factors can easily combine to alterate the exact proportions of the air/gas mixture in the combustion chamber, with a resulting impossibility for a complete oxidation of the fuel gas, and therefore a complete combustion, to be achieved in an optimum manner.
  • a solution to this particular problem may be obtained by using an oxygen sensor which will then measure the amount of oxygen existing in the flue gases in order to make sure that the combustion is taking place in a really complete manner.
  • On-off type burner control systems are also known from the state of the art. Basically, such systems comprise an atmospheric burner associated to an injector delivering the fuel gas.
  • the jet of gas discharged by said injector in correspondence of the inlet to said burner determines, by the so-called Venturi effect, the suction of an appropriate amount of combustion air from the surrounding environment.
  • the fuel gas and the combustion air get then mixed inside the burner body and are then burnt.
  • the catalyst (which is preferably deposited onto a metal wire gauze type of support) can be pre-heated in an indirect manner through an electric heating element welded onto the wire gauze and energized from an appropriate power supply source.
  • said catalyst can be pre-heated in a direct manner by letting an electric current flow directly through the metal wire gauze.
  • the electric heating element can be energized directly from the mains, ie. applying the power supply voltage as such, but this gives rise to undesired problems in connection with the need for the heating element to be insulated electrically with respect to the metal wire gauze.
  • direct heating on the contrary, the need arises to provide a low-voltage, high-current (eg. 300 A) transformer for heating up the catalyst-carrying gauze, and the catalyst itself, in a very short time.
  • a transformer of this kind is however undesirably complex, expensive and bulky, so that it simply cannot be considered for use in connection with household-type appliances.
  • a burner 1 which may be a gas burner of the traditional type, provided with an inlet 2 adapted to receive fuel gas from an injector 3.
  • an injector 3 is connected to a gas supply pipe 4 through an electromagnetic valve 5 or similar shut-off device.
  • Both the inlet 2 of the burner and the injector 3 are arranged and sized so as to ensure that an adequate amount of air, such as to enable the gas to be burnt completely, is taken by suction, owing to said Venturi effect, into the burner 1 through the inlet 2 thereof.
  • a catalyst 10 which is preferably formed by a catalytic wire gauze arrangement.
  • An electronic control arrangement 6 comprises an output 7 by means of which it is adapted to drive the gas control valve 5 in an ON-OFF cycling manner, ie. by letting it switch selectively between a closed condition and an open one.
  • the arrangement 6 may be formed by an electronic board comprising a Motorola 6805 microcontroller, with a first input 8 (of a potentiometric type, for instance), a second driver input 14 and a further output 9 of the digital type, as well as with a storage memory programmed according to a pre-determined operational cycle (a cooking cycle, for instance).
  • a control knob 11, or any similar device provided to adjust the heat output of the burner in the desired manner, may be associated to the input 8 of the electronic control arrangement 6.
  • a pair of electrodes 12 that are driven by the output 9 of the electronic control arrangement 6 through an ignition device 13 that may be of the high-voltage type with associated transformer.
  • a temperature sensor 15 which may for instance consists even of a simple thermocouple, is adapted to measure the temperature of the catalytic wire gauze 10 and to drive the input 14 of the electronic control arrangement 6 accordingly, said electronic control arrangement 6 being programmed so as to cause the electromagnetic gas-supply valve 5 to close, through the output 7, when (in a first operational phase that will be described in a more detailed manner farther on) the temperature sensor 15 detects a temperature of the catalyst 10 exceeding by a certain value A (eg. 20°C) the temperature value T at which the catalytic reaction is triggered.
  • A eg. 20°C
  • Such a triggering temperature is pre-determined and depends on the characteristics of the catalyst 10, as well as on the type of fuel being used. For instance, such a triggering temperature T will have a value of approx. 300°C when LPG is used as a fuel and a platinum and palladium based alloy as a catalyst.
  • the electronic control arrangement 6 is also programmed so as to cause, through the output 7, the electromagnetic gas-supply valve 5 to open, when (in the above cited first operational phase) the temperature sensor 15 detects a temperature of the catalyst 10 which lies by a pre-determined value B (eg., 5 to 10°C) below the aggregate value T+A, wherein such a temperature value B will in any case be lower than the temperature value A, for reasons that will be more clearly explained farther on).
  • a pre-determined value B eg., 5 to 10°C
  • An operational cycles begins at the instant t 0 , when the arrangement causes the gas-supply valve 5 to open.
  • the gas delivered by the injector 3 flows into the body of the burner 1 while mixing with the air taken in by Venturi effect through the burner inlet 2.
  • the output 9 of the control arrangement 6 energizes the ignition device 13 for a pre-set period of time T a (shown in Fig. 3 and amounting for instance to 2 seconds), so that a series of sparks are generated between the electrodes 12 which ignite the gas/air mixture escaping from the burner 1.
  • T a shown in Fig. 3 and amounting for instance to 2 seconds
  • the electronic control arrangement 6 is able to measure the temperature of the catalyst wire gauze 10 and, when such a temperature is detected to reach the afore cited value T+A, the output 7 causes the electromagnetic gas-supply valve 5 to close, with the resulting extinction of the flame, at an instant t 1 .
  • this initial heating-up phase t 0 -t 1 may for instance have a duration situated anywhere between approx. 5 and 10 seconds.
  • the output 7 of the electronic control arrangement 6 causes the electromagnetic gas-supply valve 5 to open again in correspondence of an instant t 2 .
  • the period of time from t 0 through to t 2 represents the afore mentioned first operational phase.
  • the heat output of the burner 1 is effectively controlled through a sequence of ignitions and extinctions taking place at a quite high rate so as to correspondingly reduce temperature fluctuations and enable thermal energy to be transmitted in a substantially continuous pattern throughout the time.
  • the ratio of the ignition to the extinction time can be varied so as to suit any possible requirement.
  • a relatively long period t 2 -t 3 be provided in view of allowing an adequate amount of thermal energy to reach to food to be cooked, after which the cooking cycle can then go on with an substantially constant sequence of alternating ignitions and extinctions until it comes to its end (t n ).

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Control Of Combustion (AREA)
  • Regulation And Control Of Combustion (AREA)
  • Gas Burners (AREA)

Claims (3)

  1. Steuervorrichtung für einen katalytischen Brenner, umfassend einen mit einer katalytischen Einrichtung (10) verbundenen Brenner, welcher so gestaltet ist, daß ihm über eine Ventileinrichtung (5), die durch eine elektronische Steuereinrichtung (6) gesteuert wird, wobei letztere auch eine mit dem Brenner verbundene Zündeinrichtung betreibt, Brennstoff zugeführt wird, und die Steuereinrichtung (6) mit einer Sensoreinrichtung (15) verbunden ist, welche die Temperatur der katalytischen Einrichtung (10) erfaßt, dadurch gekennzeichnet daß die Steuereinrichtung (6) während einer ersten Funktionsphase (t0-t2) die Ventileinrichtung (5) schfießt und die Zufuhr von Brenstoff zum Brenner sperrt, wenn die Temperatur der katalytischen Einrichtung (10) eine festgesetzte Temperatur T um einen bestimmten Wert A übersteigt, und die katalytische Reaktion des Brenners (1, 10) auslöst, und andererseits die Ventileinrichtung (5) öffnet, wenn die Temperatur der katalytischen Einrichtung (10) um einen festgesetzten wert B unter den Wert T + A abfällt, wobei B < A ist.
  2. Steuervorrichtung für einen katalytischen Brenner nach Anspruch 1, dadurch gekennzeichnet, daß die Steuereinrichtung (6) so gestaltet ist, daß sie nach der ersten Funktionsphase (t0-t2) die Ventileinrichtung (5) während einer Sequenz (t2-tn) in programmierter Weise abwechselnd zum Schließen und Öffnen veranlaßt, so daß die Temperatur der katalytischen Einrichtung (10) normalerweise oberhalb des auslösenden Wertes T gehalten wird.
  3. Steuervorrichtung für einen katalytischen Brenner nach Anspruch 2, dadurch gekennzeichnet, daß die elektronische Steuereinrichtung (6) die Schließ- und Öffnungsphasen der Ventileinrichtung (5) während der Sequenz (t2-tn) so variieren kann, daß der Wärmeausstoß des katalytischen Brenners (1) dem Wert entspricht, welcher durch eine Einstelleinrichtung (8, 11) vorgegeben wurde.
EP96109737A 1995-08-01 1996-06-18 Steuervorrichtung für katalytische Gasbrenner Expired - Lifetime EP0757207B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT95PN000042A IT1282428B1 (it) 1995-08-01 1995-08-01 Sistema di controllo per bruciatore catalitico
ITPN950042 1995-08-01

Publications (2)

Publication Number Publication Date
EP0757207A1 EP0757207A1 (de) 1997-02-05
EP0757207B1 true EP0757207B1 (de) 1998-09-23

Family

ID=11395053

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96109737A Expired - Lifetime EP0757207B1 (de) 1995-08-01 1996-06-18 Steuervorrichtung für katalytische Gasbrenner

Country Status (4)

Country Link
EP (1) EP0757207B1 (de)
DE (1) DE69600683T2 (de)
ES (1) ES2124611T3 (de)
IT (1) IT1282428B1 (de)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69941535D1 (de) * 1998-12-18 2009-11-26 Panasonic Corp Katalytische verbrennungseinrichtung
IT1310192B1 (it) * 1999-03-19 2002-02-11 Worgas Bruciatori Srl Metodo e mezzi per il controllo di sicurezza di bruciatori.
FR2791415B1 (fr) * 1999-03-25 2001-06-15 Sunkiss Aeronautique Procede de combustion catalytique emettant un rayonnement infrarouge, avec controle de la puissance de ce dernier
BRPI1105370A2 (pt) 2011-12-20 2013-11-12 Whirlpool Sa Sistema de combustão para queimadores de equipamentos de cocção
EP2930424B1 (de) * 2014-04-11 2017-05-31 E.G.O. ELEKTRO-GERÄTEBAU GmbH Verfahren zum Betrieb eines Gasbrenners
WO2018095988A1 (de) * 2016-11-25 2018-05-31 Frima International Ag Brennersystem für ein gargerät sowie verfahren zum betreiben eines brennersystems für ein gargerät

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5656529A (en) * 1979-10-15 1981-05-18 Osaka Gas Co Ltd Safety device for gas burning device
US4552304A (en) * 1984-03-22 1985-11-12 Papazian Arthur S Electronic gas valve pulsator
JPS61168725A (ja) * 1985-01-21 1986-07-30 Babcock Hitachi Kk 触媒燃焼装置
JPS62266317A (ja) * 1986-05-09 1987-11-19 Osaka Gas Co Ltd 触媒燃焼バ−ナの運転方法
JP2604164B2 (ja) * 1987-07-14 1997-04-30 バブコツク日立株式会社 触媒燃焼装置
DE3829677C2 (de) * 1988-09-01 1997-12-11 Lve Verfahrenselektronik Gmbh Verfahren und Anordnung zur Regelung von pulssteuerbaren Brennern in einer wärmetechnischen Anlage

Also Published As

Publication number Publication date
ITPN950042A0 (it) 1995-08-01
ITPN950042A1 (it) 1997-02-01
DE69600683D1 (de) 1998-10-29
EP0757207A1 (de) 1997-02-05
ES2124611T3 (es) 1999-02-01
DE69600683T2 (de) 1999-02-18
IT1282428B1 (it) 1998-03-23

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