EP0168700B1 - Système de régulation pour générateur de vapeur - Google Patents

Système de régulation pour générateur de vapeur Download PDF

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Publication number
EP0168700B1
EP0168700B1 EP85108086A EP85108086A EP0168700B1 EP 0168700 B1 EP0168700 B1 EP 0168700B1 EP 85108086 A EP85108086 A EP 85108086A EP 85108086 A EP85108086 A EP 85108086A EP 0168700 B1 EP0168700 B1 EP 0168700B1
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EP
European Patent Office
Prior art keywords
probe
accordance
combustion
combustion gases
errors
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
EP85108086A
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German (de)
English (en)
Other versions
EP0168700A1 (fr
Inventor
Karlheinz Wolfmüller
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.)
Deutsches Zentrum fuer Luft und Raumfahrt eV
Original Assignee
Deutsches Zentrum fuer Luft und Raumfahrt eV
Deutsche Forschungs und Versuchsanstalt fuer Luft und Raumfahrt eV DFVLR
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.)
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Publication date
Application filed by Deutsches Zentrum fuer Luft und Raumfahrt eV, Deutsche Forschungs und Versuchsanstalt fuer Luft und Raumfahrt eV DFVLR filed Critical Deutsches Zentrum fuer Luft und Raumfahrt eV
Priority to AT85108086T priority Critical patent/ATE50355T1/de
Publication of EP0168700A1 publication Critical patent/EP0168700A1/fr
Application granted granted Critical
Publication of EP0168700B1 publication Critical patent/EP0168700B1/fr
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/003—Systems for controlling combustion using detectors sensitive to combustion gas properties
    • 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
    • F23N1/022—Regulating fuel supply conjointly with air supply using electronic means
    • 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
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel

Definitions

  • the invention relates to a control method for a steam generator for controlling mass flows of an oxidizer and a fuel supplied to a combustion in stoichiometric ratios.
  • the invention is therefore based on the object of developing a control method of the type described at the outset which enables control of the mass flows in essentially stoichiometric ratios.
  • control variables for the control are first determined on the basis of direct measurements of the mass flows supplied to the combustion, so that a rough specification of the control variables can be made very quickly by the direct control without large control-related dead times and the ratios of the mass flows are approximately stoichiometric Conditions.
  • direct measurements are subject to an error which is essentially caused by variations in the thermodynamic state variables of the oxidizer and the fuel and, at the same time, is also subject to dynamic changes.
  • Another advantage of the control according to the invention is that this error is detected by the subsequent analysis of the combustion gases by means of the probe and leads to a correction of the control variables within a time interval that is smaller than the time constant of the dynamic changes in the error.
  • the control method according to the invention can thus correct systematic errors occurring in the rough specification of the control variables with sufficient speed and consequently regulate the mass flows to essentially stoichiometric conditions. Furthermore, due to the continuous determination of the errors, the proposed control method also enables transient operating states, such as e.g. B. the start of the steam generator to control with the required accuracy.
  • transient operating states such as e.g. B. the start of the steam generator to control with the required accuracy.
  • a very precise specification of the control variables on the basis of direct measurements is possible if the measurements of the mass flows supplied are carried out by means of a differential pressure method, so that subsequent corrections are only required to an extremely small extent.
  • the differential pressure method is particularly preferable to other measuring methods with gases under high absolute pressure and can work with an error of approximately 1% if the individual components are carefully selected and designed.
  • the probes that can be used to analyze the combustion gases generally place certain demands on the state variables of the combustion gases to be examined, ie an exact analysis of these gases is only possible at a certain temperature and a certain pressure. For this reason, it is advantageous if the combustion gases are removed for analysis by means of the probe at a point in the steam generator at which they have suitable state variables for the analysis by means of the probe, these state variables without energy being supplied within the framework of the general gas equation Ratios, e.g. B. can be changed by expanding. This has the advantage that a complex preparation of the combustion gases to be examined, for. B. by Er heating or cooling, which generally has a disadvantageous effect on the time constant when determining the error by means of the probe, is omitted before an analysis by the probe.
  • the combustion gases are mostly present in the steam generator under pressures that are too high for the probe.
  • a very simple and inexpensive adaptation to the probe is possible if the combustion gases are expanded to a pressure suitable for them before reaching the probe.
  • the combustion gases are removed at a point in the steam generator at which they have a significantly higher pressure and a significantly higher temperature than are suitable for the probe, but the pressure and temperature are simultaneously reduced by the expansion, so that both state variables meet the requirements of the probe.
  • the point in the steam generator described above, at which the combustion gases are removed, must therefore be selected so that the temperature minus the cooling which occurs when the pressure is reduced corresponds to the operating temperature of the probe.
  • Different analysis methods can be used to analyze the combustion gases in the probe. For example, mass spectrometry, gas chromatography, optical methods and also measurements of thermal conductivity are available. In all of these processes, complex sample gas processing is required to meet the device-specific requirements so that process-related malfunctions are avoided. In addition, the time constants for an analysis of the combustion gases are essentially in the range of minutes. With regard to the disadvantages of the methods mentioned, it is particularly advantageous if the combustion gases are analyzed by means of a solid electrolyte probe.
  • zirconium oxide (Zr 0 2 ) is used as the solid electrolyte.
  • the advantage of this zirconium oxide probe is that it is superior to the abovementioned options due to its sensitivity and above all its speed. It allows an analysis of the combustion gases with a time constant in the range of tenths of a second.
  • Another advantage of the solid electrolyte probe is that it has a drastic change in its characteristic curve in the area of the stoichiometric point, ie at the point of transition between an excess of oxidizer and an excess of unburned fuel, and consequently the stoichiometric point is exceeded or fallen short of by simple means and extremely high accuracy can be demonstrated.
  • the probe is operated with ambient air as the reference gas.
  • FIG. 1 A block diagram shown in FIG. 1 of a hydrogen / oxygen steam generator system according to the invention for the thermal conversion of hydrogen (H 2 ) and oxygen (0 2 ) to H 2 0 has a reaction space 10, which has a first feed device 12 for hydrogen and a second feed device 14 represents oxygen.
  • a third feed device 16 for water opens into the reaction space 10.
  • a measuring point 20 is provided in the first feed device 12 to determine a mass flow of hydrogen introduced into the reaction chamber 10 from the first feed device 12 by means of an differential pressure method.
  • the differential pressure method works with orifice systems inserted in a supply line and provides for a measurement of the absolute pressure PH 2 in front of the orifice system, the differential pressure DPH 2 between the absolute pressure in front of the orifice system and a pressure determined in the area of the orifice system and the absolute temperature TH 2 of the hydrogen gas.
  • the mass flow of the hydrogen MH 2 delivered from the first feed device 12 to the reaction space 10 can be determined by means of a first program 22.
  • a second measuring point 24 determines the quantities P0 2 in an analogous manner to the first measuring point 20 by means of the differential pressure method.
  • DP0 2 and T0 2 of the oxygen supplied to the reaction chamber 10 and a second program 26 of the computer system calculates the mass flow M0 2 from this .
  • a line 34 is provided for branching off a small amount of superheated steam from the reaction space 10.
  • This line 34 leads via a throttle 36 to a probe 38 which is used to analyze the superheated steam with regard to an excess of hydrogen or oxygen contained therein.
  • the throttle 36 is necessary because the superheated steam which is branched off from the reaction space 10 through the line 34 has a pressure greater than 50 bar and a temperature in the range from 500 to 2000 ° C.
  • the probe 38 only works properly if it also contains gas a pressure of approximately 1 bar and a temperature of approximately 800 ° C. Such a reduction in pressure is possible by relieving the superheated steam in the throttle 36, it being advantageous if the superheated steam expands to one for the probe 38 optimal operating temperature of around 800 ° C cools down.
  • the probe 38 Corresponding to the oxygen or hydrogen excess present in the branched superheated steam, the probe 38 generates an electromotive force and consequently a measured variable F, which in turn depends on the measurement errors in the first measuring point 20 and the second measuring point 24 and the deviations from a stoichiometric ratio between hydrogen and indicates oxygen.
  • This measured variable F is entered into the third program 28 via an algorithm based on an error model and leads to a correction of the control variable SH 2 and S0 2 calculated by this program 28 and consequently to a correction of the positions of the slides 30 or 32.
  • the probe 38 shown in FIG. 2 comprises an outer tube-like housing 42, into which the line 34 for supplying the superheated steam opens at one end, the mouth of the line 34 being simultaneously provided with a constriction 44 for throttling a superheated steam stream.
  • openings 56 are arranged in its wall surfaces for discharging the superheated steam.
  • a first tube 46 is arranged coaxially to the tube-like housing 42 and has an outer diameter which is smaller than the inner diameter of the tube-like housing 42 and is closed at its end facing the mouth of the line 34 by a ceramic plate 48 made of zirconium oxide. This ceramic plate 48 separates the superheated steam flowing into the interior of the housing 42 via the line 34 from an interior of the tube 46.
  • a baffle plate 50 is provided between the latter and the mouth of the line 34 coaxially with the housing 42.
  • the first tube 46 has a plurality of heating windings 52 on its circumference, which allow the tube 46 and thus indirectly the ceramic plate 48 held thereon to be heated.
  • a second tube 54 which is arranged coaxially to the tube and which enables a blow on a side of the ceramic plate 48 facing away from the superheated steam with ambient air.
  • the superheated steam flow supplied through line 34, throttled in constriction 44 and expanded to a pressure of 1 bar in housing 42, is first deflected by baffle plate 50 along inner wall surfaces of housing 42 and forms vortices behind baffle plate 50 and in front of ceramic plate 48 , so that the ceramic plate 48 is continuously flowed by superheated steam.
  • the superheated steam then flows in an intermediate space between the first tube 46 and the inner wall of the housing 42 and escapes from the housing through the openings 56.
  • the ceramic plate 48 is kept at its optimum operating temperature by the hot steam. If this is not the case, there is the possibility of heating the ceramic plate 48 to operating temperature by means of the heating windings 52.
  • the side of the plate 48 facing away from the superheated steam is continuously blown with ambient air, which is then discharged again in an intermediate space between the second tube 54 and an inner wall of the first tube 46.
  • the ceramic plate 48 made of zirconium oxide represents the actual solid electrolyte which, depending on the difference between an oxygen / hydrogen concentration of the superheated steam and the oxygen concentration of the ambient air, now has an electromotive force (EMF), i.e. creates a voltage between the side with superheated steam and the side with the ambient air.
  • EMF electromotive force
  • both sides of the ceramic plate 48 are provided with a porous platinum layer 58, 60.
  • Each of these platinum layers 58, 60 is connected to one of two electrical lines 62, 64 leading out of the housing 42, which lead to a measuring device 66 arranged outside the housing 42 for determining the electromotive force.
  • Fig. 3 the dependence of the electromotive force (EMF) in millivolts of a respective excess concentration (C) of hydrogen (H 2 ) of oxygen (0 2 ) is shown, which when using the probe described with a ceramic plate 48 made of zirconium oxide for superheated steam was measured.
  • EMF electromotive force
  • the intersection of these two straight lines with different slopes is exactly the stoichiometric point, ie the point at which both the oxygen and the excess hydrogen concentration are zero and the superheated steam contains pure water vapor.
  • the strong change in the EMF when the stoichiometry point is exceeded from excess oxygen concentration to excess hydrogen concentration is used to determine the error in the measurement of the mass flow ratios at the measuring points 20, 24 and enables the combustion processes in the reaction space to be kept in the stoichiometric range in a simple manner.
  • the EMF determined with the measuring device 66 is digitized in the usual way and is then available as an error F for the corrector of the control variables SH 2 and S0 2 by the third program 28.
  • a time delay between the measurement of the respective mass flows at the measuring points 20 and 24 and the presence of the size F is due to the time it takes for the gases to get from the individual measuring points 20 or 24 to the reaction space 10, the time period that the combustion gases need to get to the confluence of line 34 in the reaction space, the time it takes for the combustion gases or superheated steam to flow through line 34 to the ceramic plates 48 and the time it takes to build up the EMF, ie the voltage in the ceramic plate 48 is necessary.
  • Time constants of the measuring device and a subsequent digitization of the measured voltages will generally be negligible compared to the previously mentioned time periods.
  • the sum of all the times mentioned was determined experimentally in the preferred exemplary embodiment and is approximately 300 to 4 00 milliseconds. Such a time delay is sufficient to correct the systematic measurement errors which generally occur in the differential pressure method, since these are essentially caused by variations in the state variables of the measured gases, which are generally subject to fluctuations with time constants in the minute range.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Measuring Oxygen Concentration In Cells (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Regulation And Control Of Combustion (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)

Claims (8)

1. Procédé de régulation pour un générateur de vapeur, pour régler des débits massiques d'un oxydant et d'un combustible acheminés à une combustion dans des proportions stoechiométri- ques qui correspondent à un état de travail, caractérisé en ce que, pour la régulation, on détermine une variable de commande pour le débit massique de l'oxydant ainsi qu'une variable de commande pour le débit massique de combustible sur la base de mesures des deux débits massiques acheminés, et on effectue la comparaison de ces variables avec les proportions stoechio- métriques fixées par la théorie, en ce qu'on détermine en continu au moyen d'une sonde les erreurs décelées au cours de ces mesures, par une analyse des gaz de combustion effectuée après la combustion, en ce qu'on utilise ces erreurs pour corriger les variables de commande et en ce que la correction s'effectue avec une constante de temps qui est inférieure à la constante de temps des variations dynamiques des erreurs.
2. Procédé de régulation selon la revendication 1, caractérisé en ce que les mesures des débits massiques acheminées sont excécutées en phase gazeuse.
3. Procédé de régulation selon la revendication 1 ou 2, caractérisé en ce que les mesures des débits massiques acheminés sont exécutées à l'aide d'un procédé de pression différentielle.
4. Procédé de régulation selon une des revendications précédentes, caractérisé en ce que les gaz de combustion destinés à être analysés au moyen de la sonde sont prélevés en un point du générateur de vapeur où ils possèdent des variables d'état qui sont appropriées pour permettre d'exécuter l'analyse au moyen de la sonde.
5. Procédé de régulation selon la revendication 4, caractérisé en ce que, avant d'atteindre la sonde, les gaz de combustion sont détendus à une pression appropriée pour cette dernière.
6. Procédé de régulation selon une des revendications précédentes, caractérisé en ce que l'analyse des gaz de combustion est exécutée au moyen d'une sonde à électrolyte solide.
7. Procédé de régulation selon la revendication 6, caractérisé en ce que, comme électrolyte solide, on utilise de l'oxyde de zirconium (Zr02).
8. Procédé de régulation selon la revendication 7, caractérisé en ce que la sonde à oxyde de zirconium est alimentée en air ambiant servant de gaz de référence.
EP85108086A 1984-07-02 1985-06-29 Système de régulation pour générateur de vapeur Expired - Lifetime EP0168700B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85108086T ATE50355T1 (de) 1984-07-02 1985-06-29 Regelungsverfahren fuer dampferzeuger.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3424314A DE3424314C1 (de) 1984-07-02 1984-07-02 Regelungsverfahren fuer Dampferzeuger
DE3424314 1984-07-02

Publications (2)

Publication Number Publication Date
EP0168700A1 EP0168700A1 (fr) 1986-01-22
EP0168700B1 true EP0168700B1 (fr) 1990-02-07

Family

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Family Applications (1)

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EP85108086A Expired - Lifetime EP0168700B1 (fr) 1984-07-02 1985-06-29 Système de régulation pour générateur de vapeur

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US (1) US4655392A (fr)
EP (1) EP0168700B1 (fr)
JP (1) JPH0756364B2 (fr)
AT (1) ATE50355T1 (fr)
CA (1) CA1229144A (fr)
DE (1) DE3424314C1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5367470A (en) * 1989-12-14 1994-11-22 Exergetics Systems, Inc. Method for fuel flow determination and improving thermal efficiency in a fossil-fired power plant

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL280005A (fr) * 1962-06-21
FR2260751B1 (fr) * 1974-02-08 1976-06-25 Peugeot & Renault
JPS5332201A (en) * 1976-09-03 1978-03-27 Westinghouse Electric Corp Boiler controlling apparatus
US4238185A (en) * 1977-05-25 1980-12-09 Telegan Limited Control system for a burner
JPS5479301A (en) * 1977-12-05 1979-06-25 Japan Atom Energy Res Inst Method of producing steam and its device
US4231733A (en) * 1978-05-31 1980-11-04 Westinghouse Electric Corp. Combined O2 /combustibles solid electrolyte gas monitoring device
US4303194A (en) * 1980-02-28 1981-12-01 U.S. Steel Corporation Smoke prevention apparatus
US4360336A (en) * 1980-11-03 1982-11-23 Econics Corporation Combustion control system
DE3221660A1 (de) * 1981-06-11 1983-01-05 Paul G. Dipl.-Ing. Dr.techn. 8010 Graz Gilli Verfahren zum zwecke der optimalen verbrennung bei feuerungen
DE3125513A1 (de) * 1981-06-29 1983-01-13 Siemens AG, 1000 Berlin und 8000 München "verfahren zum betrieb einer vergasungsbrenner/heinzkesselanlage"
JPS58127001A (ja) * 1982-01-25 1983-07-28 運輸省船舶技術研究所長 水素酸素内燃式蒸気ボイラ
JPS5984022A (ja) * 1982-11-08 1984-05-15 Ebara Corp 都市ごみ焼却設備の運転方法
JPS59212620A (ja) * 1983-05-16 1984-12-01 Toshiba Corp 燃焼排気ガス中の酸素濃度制御方法

Also Published As

Publication number Publication date
US4655392A (en) 1987-04-07
EP0168700A1 (fr) 1986-01-22
DE3424314C1 (de) 1986-01-09
JPH0756364B2 (ja) 1995-06-14
JPS6149904A (ja) 1986-03-12
CA1229144A (fr) 1987-11-10
ATE50355T1 (de) 1990-02-15

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