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EP0909922B1 - Combined gas-air control system for controlling combustion in gas fired boilers - Google Patents

Combined gas-air control system for controlling combustion in gas fired boilers Download PDF

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Publication number
EP0909922B1
EP0909922B1 EP97830520A EP97830520A EP0909922B1 EP 0909922 B1 EP0909922 B1 EP 0909922B1 EP 97830520 A EP97830520 A EP 97830520A EP 97830520 A EP97830520 A EP 97830520A EP 0909922 B1 EP0909922 B1 EP 0909922B1
Authority
EP
European Patent Office
Prior art keywords
gas
control system
burner
microcontroller
modulating valve
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
EP97830520A
Other languages
German (de)
French (fr)
Other versions
EP0909922A1 (en
Inventor
Marco Tagliaferri
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.)
Riello SpA
Original Assignee
Riello SpA
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Application filed by Riello SpA filed Critical Riello SpA
Priority to DE69709928T priority Critical patent/DE69709928T2/en
Priority to EP97830520A priority patent/EP0909922B1/en
Priority to AT97830520T priority patent/ATE211809T1/en
Priority to ES97830520T priority patent/ES2170360T3/en
Publication of EP0909922A1 publication Critical patent/EP0909922A1/en
Application granted granted Critical
Publication of EP0909922B1 publication Critical patent/EP0909922B1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/08—Regulating fuel supply conjointly with another medium, e.g. boiler water
    • F23N1/10—Regulating fuel supply conjointly with another medium, e.g. boiler water and with air supply or draught
    • F23N1/102—Regulating fuel supply conjointly with another medium, e.g. boiler water and with air supply or draught using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
    • F23N5/12—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using ionisation-sensitive elements, i.e. flame rods
    • F23N5/123—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using ionisation-sensitive elements, i.e. flame rods using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2223/00—Signal processing; Details thereof
    • F23N2223/08—Microprocessor; Microcomputer
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2223/00—Signal processing; Details thereof
    • F23N2223/36—PID signal processing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/04—Measuring pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/08—Measuring temperature
    • F23N2225/18—Measuring temperature feedwater temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/08—Measuring temperature
    • F23N2225/19—Measuring temperature outlet temperature water heat-exchanger
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2233/00—Ventilators
    • F23N2233/02—Ventilators in stacks
    • F23N2233/04—Ventilators in stacks with variable speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2233/00—Ventilators
    • F23N2233/06—Ventilators at the air intake
    • F23N2233/08—Ventilators at the air intake with variable speed
    • 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
    • F23N2241/00—Applications
    • F23N2241/06—Space-heating and heating water

Definitions

  • the present invention relates to automatic control systems for controlling the gas and/or air flow rates in gas fired boilers using an ionisation electrode as a sensing element for determining the combustion condition of the burner.
  • the most common method of monitoring the combustion process is to utilize an ionisation electrode arranged in the flame area of the burner. It is known that the current flowing through this electrode, i.e. the ionisation current, depends upon the combustion conditions. Thus, information on the actual combustion condition is obtained by directly measuring the ionisation current or by measuring the voltage across the electrode which is a function of said ionisation current.
  • the control system measures the ionisation current and derives therefrom a signal to be used as a control variable for controlling the flow rate of at least one of the combustion components, namely air and gas, supplied to the gas fired boiler.
  • the present invention relates to an automatic control system for controlling both the gas and air flow rates in gas fired boilers.
  • This automatic control system will be referred to in the description as "combined gas-air control system”.
  • the combined gas-air control system for a gas fired boiler heated by a burner in a combustion chamber includes:
  • FIG. 1 shows a gas fired boiler, generally indicated with B, comprising an airtight combustion chamber 1 in which a gas burner 2 is arranged and gas supplied via an ON-OFF valve 3 mounted on the gas supply pipe.
  • An electrically controlled modulating valve MV is arranged downstream from the ON-OFF valve 3 for the purpose of modulating the gas flow rate.
  • a finned heat exchanger 4 is placed above the gas burner 2. Overhead the gas burner 2 and the heat exchanger 4 a hood 5 is provided with a suction fan 6 for drawing fumes from the combustion chamber and expelling them via an exhaust pipe 7.
  • the suction fan 6 also sucks ambient air from the outside via a suction pipe 8 arranged coaxially to the pipe 7 and supplies it to the combustion chamber 1 in order to sustain the combustion.
  • the fan 6 is operated at adjustable speed by means of a variable-speed motor FM.
  • a pipe 9 forming the heating circuit passes through the heat exchanger 4 for heating the heating water (primary heat exchanger).
  • the heating water is supplied via a delivery pipe 10 and returns to the gas fired boiler via a return pipe 11.
  • the pipe 9 embodies a circulation pump 12 and a three-way valve 13.
  • a pipe 14 forming the circuit for the sanitary water (secondary circuit) and passing through the heat exchanger 15 for heating the sanitary water (secondary heat exchanger) departs from the three-way valve 13.
  • Sanitary water is supplied to the secondary heat exchanger 15 via a pipe 16 and after being heated it is delivered via a pipe 17 for usage.
  • the function of the combined gas-air control system of the invention is to control the gas and air flow rates in the gas fired boiler B in order to hold either the heating water temperature or the sanitary water temperature to a desired value which will be referred to in the following as set point temperature.
  • Another function of the combined gas-air control system of the invention is to improve combustion and reduce emission of harmful combustion products in gas fired boilers.
  • the combined gas-air control system of the invention comprises a microcontroller ⁇ C for operating the modulating valve MV and for adjusting the speed of the variable-speed motor FM.
  • the output control signals transmitted from the ⁇ C to the modulating valve MV and the variable-speed motor FM are indicated with I mod and V f and they correspond to the control current of the modulating valve MV and to the control voltage of the variable-speed motor FM, respectively.
  • the gas flow rate Q g and the air flow rate Q a are controlled so as to change combustion process conditions in the gas fired boiler B and to bring the heating or sanitary water temperature back to the set point predetermined by the user.
  • Q g and Q a will be referred to in the following as manipulated variables.
  • the set point temperatures of the heating and sanitary water are set typically by means of potentiometers R h and R s , respectively and the corresponding set point input signals T hr and T sr are supplied to the microcontroller ⁇ C.
  • Feedback informations relating to the heating water and sanitary water temperatures, the air pressure in the combustion chamber 1 and the combustion process conditions in the burner 2 are sensed by appropriate sensors and transmitted to the microcontroller ⁇ C.
  • temperature measuring means 18, 19 embodying standard temperature sensors are provided for measuring the heating water and the sanitary water temperatures, respectively
  • air pressure measuring means 20 embodying a standard pressure sensor are provided for measuring the air pressure in the combustion chamber
  • an ionisation electrode 21 arranged in the flame area of the burner is provided for measuring the voltage across the ionisation electrode as a function of the ionisation current through the ionisation electrode depending on the combustion process conditions of the burner 2.
  • the feedback signals transmitted from the measuring means 18, 19, 20 and 21 to the microcontroller ⁇ C are indicated with T h , T s , P a and V ion respectively.
  • lines represent signals
  • a circle is an algebraic summing point representing addition or subtraction of input signals to the point
  • rectangles are system elements and a line branching from another line indicates a division of the signal into more than one path without modification.
  • the controlled variables are the heating and the sanitary water temperatures, the air pressure in the combustion chamber and the voltage across the ionisation electrode.
  • Feedback signals T h , T s , P a and V ion proportional to the values of the controlled variables are applied to the microcontroller ⁇ C for processing.
  • Control signals V f and I mod from the microcontroller ⁇ C are transmitted to the variable-speed motor FM and the modulating valve MV and control of the manipulated variables Q a and Q g in response to said control signals is thereby obtained.
  • the control element 22 in response to the error signal E(T) sequentially performs a proportional+integral+derivative (PID) control mode and a proportional (P) control mode.
  • PID proportional+integral+derivative
  • Said control element 23 performs in sequence a PID control mode and P control mode and adjusts the control voltage V f applied to the variable-speed motor FM so as to change the manipulated variable Q a , i.e. the air flow rate, in response to the error signal E(P).
  • the output signal P ac from the control element 22 is also applied to processing elements 24 and 25 which calculate the theoretical values of the voltage across the ionisation electrode and of the modulating valve current dependent on the corrected air pressure value.
  • each processing element 24 and 25 embodies a memory in which the optimal relationships between the voltage across the ionisation electrode and the modulating valve current, respectively and the air pressure in the combustion chamber are stored.
  • the output signals from the processing elements 24 and 25 are indicated with V ion(th) and I mod(th) , respectively.
  • the control element 26 performs a P control mode and determines a corrected value of the control current in the modulating valve MV.
  • Operation of the burner is also monitored by a thermostat 27 arranged in the burner area and connected to the ⁇ C.
  • the thermostat 27 signals the malfunctioning to the ⁇ C which then shuts down the burner.
  • the rpm of the fan motor and the modulating valve current can be adjusted for ensuring the required air Q a and gas Q g flow rates according to the set point temperatures of the heating or sanitary water that is delivered to usage.
  • a change in the rpm of the fan motor and in the throttle of the modulating valve will occur.
  • operation of the burner is also automatically adjusted by control element 26 when the type of gas supplied to the burner changes.
  • the combined gas-air control system of the invention ensures optimal operation of the gas fired boiler with respect to NOx and CO emissions and efficiency.

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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)

Abstract

The combined gas-air control system for gas fired boilers (B) including a microcontroller ( mu C) with memory means, set point temperature selector means (Rh,Rs), measuring means (18,19,20,21), a thermostat (27), a variable-speed fan (6), a gas modulating valve (MV) in which the microcontroller ( mu C) comprises: first controlling means (22) for correcting the error signal E(T)=Trh-Th or E(T)=Trs-Ts and for controlling the air pressure in the combustion chamber (1), second controlling means (23) for correcting the error signal E(P)=Pac-Pa and for controlling the speed of the fan, processing means (24,25) for processing the ionisation voltage and the modulating valve current signals, third controlling means (26) for correcting the error signal E(V)=Vion(th)-Vion and the modulating valve current. <IMAGE>

Description

  • The present invention relates to automatic control systems for controlling the gas and/or air flow rates in gas fired boilers using an ionisation electrode as a sensing element for determining the combustion condition of the burner.
  • New standards regarding gas fired boilers are limiting the allowable emissions of harmful products resulting from combustion, specifically CO and NOx, to a very low level.
  • In order to respect the new standards, improvements in the combustion process in gas fired boilers have proved to be necessary. Therefore, several manufacturers have provided their gas fired boilers with automatic control systems by which optimal operation of the burner in any condition of thermal load can be ensured.
  • The most common method of monitoring the combustion process is to utilize an ionisation electrode arranged in the flame area of the burner. It is known that the current flowing through this electrode, i.e. the ionisation current, depends upon the combustion conditions. Thus, information on the actual combustion condition is obtained by directly measuring the ionisation current or by measuring the voltage across the electrode which is a function of said ionisation current. The control system measures the ionisation current and derives therefrom a signal to be used as a control variable for controlling the flow rate of at least one of the combustion components, namely air and gas, supplied to the gas fired boiler.
  • The present invention relates to an automatic control system for controlling both the gas and air flow rates in gas fired boilers. This automatic control system will be referred to in the description as "combined gas-air control system".
  • More particularly, the combined gas-air control system for a gas fired boiler heated by a burner in a combustion chamber includes:
    • a microcontroller with memory means,
    • selector means for predetermining set point temperatures Trh and Trs of the heating and sanitary water respectively,
    • measuring means providing signals Th, Ts, Pa and Vion corresponding to the temperature of the heating and sanitary water, the air pressure in the combustion chamber and the ionisation voltage in the flame area of the burner, respectively and for communicating said signals back to the microcontroller,
    • a thermostat for monitoring operation of the burner and for preventing its overheating,
    • a fan operated by a variable-speed motor for controlling the flow rate Qa of air supplied to the combustion chamber,
    • an electrically controlled modulating valve for modulating the flow rate Qg of gas supplied to the burner, characterized in that said microcontroller comprises:
    • first controlling means for producing a corrective action in response to an error signal E(T)=Trh-Th or E(T)=Trs-Ts and for giving an output signal Pac corresponding to a corrected value of air pressure in the combustion chamber,
    • second controlling means for producing a corrective action in response to an error signal E(P)=Pac-Pa and for adjusting the control voltage Vf applied to the variable-speed motor,
    • processing means for calculating theoretical optimal values of the ionisation voltage and the modulating valve current in response to the output signal Pac from said first controlling means and for producing said theoretical values as output signals Vion(th) and Imod(th), respectively,
    • third controlling means for producing a corrective action in response to an error signal E(V)=Vion(th)-Vion and for giving an output signal Imodc corresponding to a corrected value of the modulating valve current, said output signal Imodc from said third controlling means being added to the output signal Imod(th) from said processing means and the resulting sum signal Imods=Imodc+Imod(th) being applied to the modulating valve.
  • The combined gas-air control system will be described in more detail with reference to the accompanying drawings, wherein:
  • Figure 1 is a schematic view of a gas fired boiler provided with the combined gas-air control system of the present invention, and
  • Figure 2 is a block diagram of the combined gas-air control system according to the present invention.
  • Figure 1 shows a gas fired boiler, generally indicated with B, comprising an airtight combustion chamber 1 in which a gas burner 2 is arranged and gas supplied via an ON-OFF valve 3 mounted on the gas supply pipe. An electrically controlled modulating valve MV is arranged downstream from the ON-OFF valve 3 for the purpose of modulating the gas flow rate. A finned heat exchanger 4 is placed above the gas burner 2. Overhead the gas burner 2 and the heat exchanger 4 a hood 5 is provided with a suction fan 6 for drawing fumes from the combustion chamber and expelling them via an exhaust pipe 7. The suction fan 6 also sucks ambient air from the outside via a suction pipe 8 arranged coaxially to the pipe 7 and supplies it to the combustion chamber 1 in order to sustain the combustion. The fan 6 is operated at adjustable speed by means of a variable-speed motor FM.
  • A pipe 9 forming the heating circuit (primary circuit), passes through the heat exchanger 4 for heating the heating water (primary heat exchanger). The heating water is supplied via a delivery pipe 10 and returns to the gas fired boiler via a return pipe 11. The pipe 9 embodies a circulation pump 12 and a three-way valve 13. A pipe 14 forming the circuit for the sanitary water (secondary circuit) and passing through the heat exchanger 15 for heating the sanitary water (secondary heat exchanger) departs from the three-way valve 13. Sanitary water is supplied to the secondary heat exchanger 15 via a pipe 16 and after being heated it is delivered via a pipe 17 for usage.
  • The function of the combined gas-air control system of the invention is to control the gas and air flow rates in the gas fired boiler B in order to hold either the heating water temperature or the sanitary water temperature to a desired value which will be referred to in the following as set point temperature.
  • Another function of the combined gas-air control system of the invention is to improve combustion and reduce emission of harmful combustion products in gas fired boilers.
  • In order to accomplish this, the combined gas-air control system of the invention comprises a microcontroller µC for operating the modulating valve MV and for adjusting the speed of the variable-speed motor FM. The output control signals transmitted from the µC to the modulating valve MV and the variable-speed motor FM are indicated with Imod and Vf and they correspond to the control current of the modulating valve MV and to the control voltage of the variable-speed motor FM, respectively.
  • In response to the control signals Imod and Vf transmitted from the µC to the modulating valve MV and the variable-speed motor FM, the gas flow rate Qg and the air flow rate Qa are controlled so as to change combustion process conditions in the gas fired boiler B and to bring the heating or sanitary water temperature back to the set point predetermined by the user. Qg and Qa will be referred to in the following as manipulated variables.
  • The set point temperatures of the heating and sanitary water are set typically by means of potentiometers Rh and Rs, respectively and the corresponding set point input signals Thr and Tsr are supplied to the microcontroller µC. Feedback informations relating to the heating water and sanitary water temperatures, the air pressure in the combustion chamber 1 and the combustion process conditions in the burner 2 are sensed by appropriate sensors and transmitted to the microcontroller µC. To accomplish this, temperature measuring means 18, 19 embodying standard temperature sensors are provided for measuring the heating water and the sanitary water temperatures, respectively, air pressure measuring means 20 embodying a standard pressure sensor are provided for measuring the air pressure in the combustion chamber, and an ionisation electrode 21 arranged in the flame area of the burner is provided for measuring the voltage across the ionisation electrode as a function of the ionisation current through the ionisation electrode depending on the combustion process conditions of the burner 2. The feedback signals transmitted from the measuring means 18, 19, 20 and 21 to the microcontroller µC are indicated with Th, Ts, Pa and Vion respectively.
    • OPERATION
  • Operation of the combined gas-air control system will be now described with reference to the block diagram of Figure 2.
  • According to the usual conventions, lines represent signals, a circle is an algebraic summing point representing addition or subtraction of input signals to the point, rectangles are system elements and a line branching from another line indicates a division of the signal into more than one path without modification.
  • The controlled variables are the heating and the sanitary water temperatures, the air pressure in the combustion chamber and the voltage across the ionisation electrode. Feedback signals Th, Ts, Pa and Vion proportional to the values of the controlled variables are applied to the microcontroller µC for processing. Control signals Vf and Imod from the microcontroller µC are transmitted to the variable-speed motor FM and the modulating valve MV and control of the manipulated variables Qa and Qg in response to said control signals is thereby obtained.
  • Operation of the system can be seen considering the control of the sanitary water temperature, but it should be clearly understood that a similar operation applies to the control of the heating water temperature.
  • Referring to Figure 2, the microcontroller µC compares the feedback signal Ts from the water temperature measuring means 19 with the set point signal Trs and transmits their difference, i.e. the error signal E(T)=Trs-Ts, to the control element 22 which utilizes said error signal E(T) to determine the corrected value of air pressure in the combustion chamber 1. The control element 22 in response to the error signal E(T) sequentially performs a proportional+integral+derivative (PID) control mode and a proportional (P) control mode. The output signal Pac resulting from this PID and P corrective action is compared with the feedback signal Pa from the air pressure measuring means 20 and the error signal E(P)=Pa-Pac actuates the control element 23. Said control element 23 performs in sequence a PID control mode and P control mode and adjusts the control voltage Vf applied to the variable-speed motor FM so as to change the manipulated variable Qa, i.e. the air flow rate, in response to the error signal E(P).
  • The output signal Pac from the control element 22 is also applied to processing elements 24 and 25 which calculate the theoretical values of the voltage across the ionisation electrode and of the modulating valve current dependent on the corrected air pressure value. In order to accomplish this calculation, each processing element 24 and 25 embodies a memory in which the optimal relationships between the voltage across the ionisation electrode and the modulating valve current, respectively and the air pressure in the combustion chamber are stored. The output signals from the processing elements 24 and 25 are indicated with Vion(th) and Imod(th), respectively.
  • The feedback signal Vion from the ionisation voltage measuring means 21 is compared with the output signal Vion(th) from the processing element 24 and the error signal E(V)=Vion(th)-Vion is supplied to the control element 26. In response to the error signal E(V), the control element 26 performs a P control mode and determines a corrected value of the control current in the modulating valve MV. The output signal Imodc from the control element 26 is added to the output signal Imod(th) from the processing element 25 and the resulting sum signal Imods=Imodc+Imod(th) is used to operate the modulating valve MV so as to change the manipulated variable Qg, i.e. the gas flow rate.
  • Operation of the burner is also monitored by a thermostat 27 arranged in the burner area and connected to the µC. In the case of burner overheating, the thermostat 27 signals the malfunctioning to the µC which then shuts down the burner.
  • Essentially, the rpm of the fan motor and the modulating valve current can be adjusted for ensuring the required air Qa and gas Qg flow rates according to the set point temperatures of the heating or sanitary water that is delivered to usage. When the thermal load changes, a change in the rpm of the fan motor and in the throttle of the modulating valve will occur. Moreover, operation of the burner is also automatically adjusted by control element 26 when the type of gas supplied to the burner changes. The combined gas-air control system of the invention ensures optimal operation of the gas fired boiler with respect to NOx and CO emissions and efficiency.

Claims (6)

  1. Combined gas-air control system for a gas fired boiler (B) heated by a burner (2) in a combustion chamber (1) including:
    a microcontroller (µC) with memory means,
    selector means (Rh,Rs) for predetermining set point temperatures Trh and Trs of the heating and sanitary water respectively,
    measuring means (18,19,20,21) providing signals Th, Ts, Pa and Vion corresponding to the temperature of the heating and sanitary water, the air pressure in the combustion chamber (1) and the ionisation voltage in the flame area of the burner (2), respectively and for communicating said signals back to the microcontroller (µC),
    a thermostat (27) for monitoring operation of the burner and for preventing its overheating,
    a fan (6) operated by a variable-speed motor (FM) for controlling the flow rate Qa of air supplied to the combustion chamber (1),
    an electrically controlled modulating valve (MV) for modulating the flow rate Qg of gas supplied to the burner (2),
    characterized in that said microcontroller (µC) comprises:
    first controlling means (22) for producing a corrective action in response to an error signal E(T)=Trh-Th or E(T)=Trs-Ts and for giving an output signal Pac corresponding to a corrected value of air pressure in the combustion chamber (1),
    second controlling means (23) for producing a corrective action in response to an error signal E(P)=Pac-Pa and for adjusting the control voltage Vf applied to the variable-speed motor (FM),
    processing means (24,25) for calculating theoretical optimal values of the ionisation voltage and the modulating valve current in response to the output signal Pac from said first controlling means (22) and for producing said theoretical values as output signals Vion(th) and Imod(th), respectively,
    third controlling means (26) for producing a corrective action in response to an error signal E(V)=Vion(th)-Vion and for giving an output signal Imodc corresponding to a corrected value of the modulating valve current, said output signal Imodc from said third controlling means (26) being added to the output signal Imod(th) from said processing means (25) and the resulting sum signal Imods=Imodc+Imod(th) being applied to the modulating valve (MV).
  2. Combined gas-air control system according to claim 1, characterized in that the corrective action of said first (22) and second (23) controlling means in response to the respective input error signals E(T) and E(P) embodies in combination a proportional+integral+derivative control mode and a proportional control mode.
  3. Combined gas-air control system according to claim 1, characterized in that the corrective action of said third controlling means (26) in response to the input error signal E(V) embodies a proportional control mode.
  4. Combined gas-air control system according to claim 1, characterized in that in said microcontroller (µC) the optimal relationships between the voltage across the ionisation electrode and the modulating valve current,respectively and the air pressure in the combustion chamber are stored.
  5. Combined gas-air control system according to claim 1, characterized in that said microcontroller (µC) is preferably a digital microcontroller provided with standard A/D and D/A conversion means.
  6. Combined gas-air control system according to claim 1, characterized in that said third controlling means (26) provide for an automatic adjustment of the burner operation when the type of gas supplied to the burner changes.
EP97830520A 1997-10-17 1997-10-17 Combined gas-air control system for controlling combustion in gas fired boilers Expired - Lifetime EP0909922B1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
DE69709928T DE69709928T2 (en) 1997-10-17 1997-10-17 Combined control system for gas and air for controlling the combustion of a gas boiler
EP97830520A EP0909922B1 (en) 1997-10-17 1997-10-17 Combined gas-air control system for controlling combustion in gas fired boilers
AT97830520T ATE211809T1 (en) 1997-10-17 1997-10-17 COMBINED CONTROL SYSTEM FOR GAS AND AIR FOR COMBUSTION CONTROL OF A GAS HEATING BOILER
ES97830520T ES2170360T3 (en) 1997-10-17 1997-10-17 COMBINED GAS AND AIR REGULATION SYSTEM TO REGULATE COMBUSTION IN BOILERS HEATED BY GAS.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP97830520A EP0909922B1 (en) 1997-10-17 1997-10-17 Combined gas-air control system for controlling combustion in gas fired boilers

Publications (2)

Publication Number Publication Date
EP0909922A1 EP0909922A1 (en) 1999-04-21
EP0909922B1 true EP0909922B1 (en) 2002-01-09

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Family Applications (1)

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EP97830520A Expired - Lifetime EP0909922B1 (en) 1997-10-17 1997-10-17 Combined gas-air control system for controlling combustion in gas fired boilers

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EP (1) EP0909922B1 (en)
AT (1) ATE211809T1 (en)
DE (1) DE69709928T2 (en)
ES (1) ES2170360T3 (en)

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CN102640978A (en) * 2012-05-11 2012-08-22 云南省烟草农业科学研究院 Dual-pressure air inducing heating device
CN102777886A (en) * 2012-08-13 2012-11-14 中国中元国际工程公司 Flue gas waste heat recovery device and method for gas-fired boiler

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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ATE350625T1 (en) * 2000-03-03 2007-01-15 Riello Spa CONTROL SYSTEM FOR BOILER
DE60020517T2 (en) * 2000-03-03 2006-05-04 Riello S.P.A., Legnago Gas fired kettle
NL1015797C2 (en) 2000-07-25 2002-01-28 Nefit Buderus B V Combustion device and method for controlling a combustion device.
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ITAN20020038A1 (en) * 2002-08-05 2004-02-06 Merloni Termosanitari Spa Ora Ariston Thermo Spa LAMBDA VIRTUAL SENSOR COMBUSTION CONTROL SYSTEM.
ITAN20020062A1 (en) * 2002-12-23 2004-06-24 Merloni Termosanitari Spa Ora Ariston Thermo Spa MULTIPURPOSE FORCED DRAWER BOILER.
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CN1332152C (en) * 2003-04-11 2007-08-15 株式会社庆东纳碧安 Air proportional boiler using air pressure sensor
KR20060087071A (en) * 2005-01-28 2006-08-02 주식회사 경동네트웍 Appropriate air-fuel ratio control system of oil burner using air volume sensor and its control method
EP1712841A1 (en) * 2005-04-14 2006-10-18 Immergas S.p.A. Electronic device and method for managing the exhaust of burnt gases, in particular in a boiler
WO2008017177A1 (en) * 2006-08-10 2008-02-14 Toby Ag Method for controlling a burner
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Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0674891B2 (en) * 1988-04-27 1994-09-21 リンナイ株式会社 Combustion type combustion device
JPH02161208A (en) * 1988-12-14 1990-06-21 Harman Co Ltd Fuel-burning equipment
AT397851B (en) * 1989-11-24 1994-07-25 Vaillant Gmbh HEATER
JP3366394B2 (en) * 1993-09-02 2003-01-14 株式会社ガスター Combustion device and combustion control method
DE19618573C1 (en) * 1996-05-09 1997-06-26 Stiebel Eltron Gmbh & Co Kg Gas burner regulating method controlled by ionisation electrode signal
DE19601517B4 (en) * 1996-01-17 2006-01-19 Stiebel Eltron Gmbh & Co. Kg Regulation of a gas heater

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JP2001355841A (en) * 2000-05-12 2001-12-26 Siemens Building Technologies Ag Burner control device and method of setting the control device
CN102640978A (en) * 2012-05-11 2012-08-22 云南省烟草农业科学研究院 Dual-pressure air inducing heating device
CN102777886A (en) * 2012-08-13 2012-11-14 中国中元国际工程公司 Flue gas waste heat recovery device and method for gas-fired boiler
CN102777886B (en) * 2012-08-13 2014-07-16 中国中元国际工程公司 Flue gas waste heat recovery device and method for gas-fired boiler

Also Published As

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DE69709928D1 (en) 2002-02-28
ES2170360T3 (en) 2002-08-01
EP0909922A1 (en) 1999-04-21
DE69709928T2 (en) 2002-08-29
ATE211809T1 (en) 2002-01-15

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