EP0263056B1 - Vapour temperature regulation device for a vapour generator - Google Patents

Vapour temperature regulation device for a vapour generator Download PDF

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Publication number
EP0263056B1
EP0263056B1 EP87710014A EP87710014A EP0263056B1 EP 0263056 B1 EP0263056 B1 EP 0263056B1 EP 87710014 A EP87710014 A EP 87710014A EP 87710014 A EP87710014 A EP 87710014A EP 0263056 B1 EP0263056 B1 EP 0263056B1
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EP
European Patent Office
Prior art keywords
cooler
temperature
superheater
regulator
time
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EP87710014A
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German (de)
French (fr)
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EP0263056A1 (en
Inventor
Heinrich Renze
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Siemens AG
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Siemens AG
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22G—SUPERHEATING OF STEAM
    • F22G5/00—Controlling superheat temperature
    • F22G5/12—Controlling superheat temperature by attemperating the superheated steam, e.g. by injected water sprays

Definitions

  • the invention relates to an arrangement for regulating the steam temperature of a steam generator according to the preamble of claim 1.
  • the present invention has for its object to provide an arrangement of the type specified in the preamble of claim 1, in which the steam temperature control is stable.
  • this object is achieved with the measures specified in the characterizing part of claim 1. This ensures that the steam temperature difference on the second cooler is controlled with the first controller and the first cooler as the control element and the steam outlet temperature of the steam generator is controlled with the second controller and the second cooler as the control element.
  • the temperature at the inlet of the second cooler is advantageously limited. If this limit temperature is reached, the temperature at the inlet of the second cooler is controlled instead of the temperature difference.
  • KL1 denotes a first cooler that lies in the steam path of a steam generator. It is followed by a first superheater UH1, a second cooler KL2 and a second superheater UH2.
  • the steam outlet temperature of the steam generator is converted into an electrical value by a temperature transmitter MT4, which is compared in an adder AD11 with a setpoint set in a setpoint generator SG3.
  • the outlet temperature of the steam generator is regulated to this setpoint.
  • the control difference is fed via a divider DV2, the meaning of which is explained below, and adders AD8, AD7 to the input of a PI controller PIR2, which controls a servomotor SM2 which adjusts an injection valve EV2.
  • the control loop thus closed includes the second superheater UH2, the outlet temperature of which changes only slowly when the injection water flow in the cooler KL2 changes, in accordance with a delay element with delay and compensation time.
  • the temperature at the outlet of the second cooler KL2 is therefore measured, converted into an electrical value by a converter MT3 and used as an auxiliary control variable with a short delay time.
  • a heating fault e.g. a falling steam temperature at the output of the second superheater UH2
  • the output signal of the adder AD11 becomes positive and the output signal of the adder AD7 becomes negative.
  • the injection water flow is reduced via the controller PIR2, so that the output signal of the adder AD7 becomes zero again as the temperature behind the second cooler KL2 increases.
  • the delay and compensation time of the superheater UH2 is simulated in a delay element VZ2.
  • the order of the delay element and the time constants can be determined by known methods from the delay time and the equalization time of the second superheater UH2, which can be determined after a step function has been applied.
  • Its output signal is subtracted from the undelayed signal of the converter MT3 in an adder AD9, so that its output signal, which was caused by the reduction in the quantity of injection water, decays in the opposite direction to the temperature increase at the outlet of the superheater UH2. The difference between these two signals at the adder AD7 becomes zero, so that the quantity of injection water is no longer adjusted via the controller PIR2.
  • the superheaters UH1, UH2 behave like a higher-order delay element with a delay time and an equalization time.
  • the ratio of delay to compensation time can be assumed to be independent of the steam throughput.
  • the times themselves are approximately inversely proportional to the steam flow or the load, so that they are z. B. double at half load compared to full load. This is taken into account in the delay element VZ2 in that the steam flow is detected by a flow transmitter MV and in a unit KW2 a signal proportional to the reciprocal of the flow is formed, with which the time constants of the delay element VZ2 are influenced such that they are inversely proportional to the steam flow.
  • the setpoint for the temperature difference at the cooler KL2 set in a setpoint generator SG1 is added in an adder AD6.
  • the output signal of the adder AD6 arrives at an adder AD5, which compares it with the output signal of a temperature converter MT2.
  • the control difference which corresponds to the deviation of the temperature difference at the second cooler KL2 from the setpoint set in the setpoint generator SG1, passes via a divider DV1 and adder AD3, AD2 to the input of a PI controller PIR1, which controls a servomotor SM1 with an injection valve EV1.
  • the injection quantity of the feed water into the first cooler KL1 is set in such a way that the temperature difference at the second cooler KL2 is equal to the setpoint value set with the setpoint generator SG1. Since the output signal of the delay element VZ2 is used as the signal for the temperature behind the second cooler KL2, the temperature controls are dynamically decoupled. This decoupling prevents that when the injection in the second cooler KL2 is adjusted, the controller PIR1 is immediately excited with the change in the injection into the cooler KL1, which could trigger an oscillation.
  • the minimum value selection MIN switches the limit value from the setpoint generator SG2 to the adder AD5 instead of the output signal of the adder AD6, so that the temperature upstream of the second cooler KL2 is at the limit value is held.
  • the control works with the controller PIR1 in accordance with that with the controller PIR2.
  • the enthalpy is used as the auxiliary control variable.
  • the temperature and pressure downstream of the cooler KL1 are recorded with the transmitters MT1, MP1 and fed to an enthalpy computer ER known per se.
  • Its output signal is fed directly to an adder AD1 via a delay element VZ1, in which the delay is simulated by the superheater UH1.
  • This delay element is generally of a higher order, possibly even with different time constants with a delay time and an equalization time.
  • the difference between the two signals formed in the adder AD1 is applied to the PI controller P) R1.
  • the delay of the steam generator UH1 is inversely proportional to the steam throughput
  • a signal is generated in a unit KW1, which is inversely proportional to the steam throughput, and with this signal influences the time constants of the delay element VZ1.
  • the use of the enthalpy instead of the temperature as an auxiliary control variable is advantageous because at the outlet of the first cooler KL1 the steam near the saturation area and thus the relationship between the temperature at the outlet of the first superheater UH1 and the temperature behind the first cooler KL1 can be strongly non-linear.
  • the control is adapted to the variable gain of the controlled system depending on the vapor pressure. Even if the superheater's heating output remains the same, the outlet temperature does not change by the same amount as the inlet temperature. In order to take this change in the gain of the controlled system into account, the pressure at the output of the superheater UH2 is detected with the pressure converter MP3 and fed to a function generator FG2.
  • FIG. 2 shows which values the divisor DIV2 should have for correct compensation of the controlled system gain in the superheater UH2 as a function of the pressure P at the outlet of the superheater UH2 and the temperature at its entry.
  • FIG. 3 shows as a functional block diagram how the divisor for the divider DV2 can easily be generated.
  • the temperature is ignored and only a middle straight line is generated. In practice, this is completely sufficient, since the deviation from the correct value is a maximum of 10%.
  • the function transmitter FG2 according to FIG. 3 contains a constant transmitter KG7, which is set to a value corresponding to a pressure of 70 bar. This value is compared with the output signal of the pressure transducer MP3 in an adder AD16 and the difference is fed to one input of a maximum value selection MAX. At the other input there is a value of zero. If the pressure detected by the pressure transducer MP3 is less than 70 bar, the value zero is switched through to a multiplier M7, the output value of which is therefore also zero.
  • the output signal of an adder AD17, which represents the divisor for the divider DV2, is therefore the value set in a constant encoder KG9, which is set to 1.02 in accordance with FIG.
  • the output signal of the adder AD16 and thus that of the maximum value selection MAX is positive and multiplied by the multiplier M7 by a factor set in a constant encoder KG8.
  • This factor is chosen so that the divisor for the divider DV2 is approximately equal to that for 470 ° C ( Figure 2).
  • a circuit could be used whose output signal changes depending on the temperature so that the family of curves shown in FIG. 2 is achieved.
  • the temperature difference on the superheater UH1 also depends on the pressure with constant heating output. This dependence on the controlled system gain is compensated for by dividing the control difference at the output of the adder AD5 by a pressure and temperature-dependent value which is formed in a function generator FG1.
  • the pressure and temperature dependent divisor values DIV1 are shown in FIG. 4.
  • Figure 5 shows details of the function generator FG1.
  • the values supplied by the pressure transmitter MP2 are compared in an adder AD18 with a value which corresponds to a pressure of 30 bar and is set in a constant encoder KG10.
  • the difference is multiplied by a multiplier M8 by a factor supplied by a constant encoder KG11.
  • the result is multiplied in a multiplier M9 by a difference formed in an adder AD20 and subtracted in an adder AD21 from the value 1.86 generated by a constant encoder KG13.
  • the result is fed to the divider DV1 as a divisor.
  • An adder AD19 forms the difference between the signal emitted by the temperature converter MT2 and the value set in a constant encoder KG14, which corresponds to a temperature of 440 ° .
  • the difference is fed via a function generator FG3, which generates the non-linear dependence of the divisor on the temperature shown in FIG. 4, to an adder AD20, which subtracts the output signal of the function generator FG3 from a value set in a constant generator KG12, the value one.
  • the function generator FG3 is designed such that its output signal is zero when the input signal is zero, corresponding to 440 ° , and that its output signal increases nonlinearly with increasing temperature, such that it is approximately 0.14 at 465 ° and a value at 490 ° of about 0.24.
  • the factor fed to the multiplier M9 is therefore at 440 ° one and decreases nonlinearly to approximately 0.76 with increasing temperature.
  • the output signal of the adder AD18 is zero and the divisor is the value 1.86 set in the constant encoder KG13. If the pressure rises at a constant 440 ° C., the output signal of the multiplier M8 increases and, since it is not changed in the multiplier M9 because of the multiplication by one, is subtracted from the value 1.86 in the adder AD21. The divisor therefore changes with increasing pressure in accordance with the straight line labeled 440 ° in FIG. As the temperature rises, the factor supplied by the adder AD20 to the multiplier M9 becomes smaller and thus also the subtrahend supplied to the adder AD21, so that the divisor DIV1 rises at constant pressure in accordance with the diagrams shown in FIG.
  • the multiplier M9 and the circuit forming the correction factor can be dispensed with.
  • the constant encoder KG11 is then expediently set to such a value that the divisor follows a middle line shown in FIG. 4 when the pressure changes. Such a straight line is e.g. B. for 460 ° .
  • the controller described so far shows very good stability because of the decoupling of the two control loops; Because of the long delay and compensation times of the superheaters, however, if the temperatures are determined exclusively at the outlet of the superheaters, the faults are only determined after a relatively long delay time.
  • the arrangement according to FIG. 1 contains two fault detection circuits STM1, STM2.
  • each superheater has a model with several, e.g. B. four, series-connected delay elements can be simulated. Since only the inlet and outlet temperatures are measured on the superheater, only the input signal of the first and the output signal is on the model. of the last delay element known.
  • the control difference corrected in the divider DV2 is fed to an adder AD12.
  • a differentiating element DG1 the time constant of which is equal to that of the last delay element of the model for the superheater UH2.
  • the effect of the differentiating element can be adjusted by multiplying the returned signal by a constant encoder KG1. A signal is thus available at the output of the adder AD12 which corresponds to the input of the last delay element of the superheater model.
  • the output signal of the penultimate delay element of the superheater model is determined from this signal with an adder AD13, a multiplier M2 with a constant encoder KG2 and a differentiator DG2.
  • a signal is available which corresponds to the temperature change in the middle of the superheater.
  • the speed at which the input signals of the last two delay elements are determined can be selected with the constant encoders KG1, KG2 at the inputs of the differentiators DG1, DG2.
  • the time constants of the differentiators match those of the delay elements; they are therefore also changed with the reciprocal of the steam flow.
  • the output signal of the adder AD13 is applied to a differentiating element DG3 with the same time constant as the other differentiating and delay elements. This creates a reserve for the control, the size of which depends on the ordinal number of the controlled system and can be set on a constant encoder KG3. Since the temperature behind the second cooler KL2 is changed by the control so that the temperature at the outlet of the superheater reaches the setpoint with a constant fault, the output signal of the temperature converter MT3 delayed by the delay element VZ2 is connected to the input of the fault determination circuit STM2 via the adder AD10 .
  • the second fault detection circuit STM2 works in the same way as the first STM1. Your description is therefore unnecessary.
  • FIGS. 1, 3 and 5 The exemplary embodiment is shown in FIGS. 1, 3 and 5 in the manner of a circuit diagram and has also been described for the sake of clarity. In fact, with the exception of the cooler, superheater and transmitter, the exemplary embodiment will be implemented with a programmable computer. The same applies to all configurations within the scope of the invention.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
  • Control Of Eletrric Generators (AREA)
  • Control Of Turbines (AREA)
  • Sorption Type Refrigeration Machines (AREA)
  • Bidet-Like Cleaning Device And Other Flush Toilet Accessories (AREA)

Abstract

1. Device for regulating the exit vapour temperature of a vapour generator which contains, situated one behind the other in the vapour stream, a first cooler (KL1), a first superheater (UH1), a second cooler (KL2) and a second superheater (UH2), with a regulator (PIR1) controlling the first cooler (KL1) and a second regulator (PIR2) controlling the second cooler (KL2), characterised in that a signal corresponding to the temperature difference at the second cooler (KL2) is compared with a setpoint value (SG1) and the result of the comparison is applied as the deviation to the first regulator (PIR1), and that a signal corresponding to the exit temperature of the vapour generator is compared with a setpoint value (SG3) and the result of the comparison is applied as the deviation to the second regulator (PIR2).

Description

Die Erfindung betrifft eine Anordnung zum Regeln der Dampftemperatur eines Dampferzeugers gemäß dem Oberbegriff des Anspruchs 1.The invention relates to an arrangement for regulating the steam temperature of a steam generator according to the preamble of claim 1.

Es ist bekannt, z.B. aus "Handbuch der Regelungstechnik", herausgegeben von Bleisteiner und Mangoldt, Springer-Verlag 1961, Seiten 362 bis 366, die Dampfaustrittstemperatur von Benson-Kesseln außer mit einer Feuerungsregelung dadurch zu regeln, daß ein Teil des Speisewassers vor dem Überhitzer in den Dampf eingespritzt wird, so daß dieser gekühlt wird. Eine solche Temperaturregelung hat eine kleinere Totzeit als die Feuerungsregelung, die auf die Überhitzer wirkt. Im übrigen wird im allgemeinen mit der Feuerung nicht die Temperatur, sondern der Dampfdruck geregelt. Oft sind mehrere, im allgemeinen zwei Überhitzer vorhanden, denen jeweils ein Kühler vorgeschaltet ist. Es besteht dann die Gefahr, daß sich die Kühlerregelungen beeinflussen, die Temperaturregelung instabil wird und die Einspritzventile aus dem Regelbereich gesteuert werden.It is known e.g. from "Handbuch der Steuerungstechnik", published by Bleisteiner and Mangoldt, Springer-Verlag 1961, pages 362 to 366, to regulate the steam outlet temperature of Benson boilers except by means of a combustion control system by injecting part of the feed water into the steam before the superheater so that it is cooled. Such a temperature control has a shorter dead time than the firing control, which affects the superheater. Incidentally, the furnace does not generally regulate the temperature, but the steam pressure. Often there are several, generally two superheaters, each of which is preceded by a cooler. There is then a risk that the cooler controls will influence each other, the temperature control will become unstable and the injection valves will be controlled from the control range.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, eine Anordnung der im Oberbegriff des Anspruchs 1 angegebenen Art zu schaffen, bei welcher die Dampftemperaturregelung stabil ist.The present invention has for its object to provide an arrangement of the type specified in the preamble of claim 1, in which the steam temperature control is stable.

Erfindungsgemäß wird diese Aufgabe mit den im kennzeichnenden Teil des Anspruchs 1 angegebenen Maßnahmen gelöst. Damit wird erreicht, daß mit dem ersten Regler und dem ersten Kühler als Stellglied die Dampftemperaturdifferenz am zweiten Kühler und mit dem zweiten Regler und dem zweiten Kühler als Stellglied die Dampfaustrittstemperatur des Dampferzeugers geregelt wird.According to the invention, this object is achieved with the measures specified in the characterizing part of claim 1. This ensures that the steam temperature difference on the second cooler is controlled with the first controller and the first cooler as the control element and the steam outlet temperature of the steam generator is controlled with the second controller and the second cooler as the control element.

Vorteilhaft ist die Temperatur am Eingang des zweiten Kühlers begrenzt. Wird diese Grenztemperatur erreicht, dann wird anstelle der Temperaturdifferenz die Temperatur am Eingang des zweiten Kühlers geregelt.The temperature at the inlet of the second cooler is advantageously limited. If this limit temperature is reached, the temperature at the inlet of the second cooler is controlled instead of the temperature difference.

Damit die Temperaturabweichungen gering sind, sind vorteilhaft Maßnahmen getroffen, mit denen die Temperaturabweichungen in den Überhitzern, z. B. infolge von Beheizungsstörungen, rasch ermittelt und ausgeregelt werden.So that the temperature deviations are small, measures are advantageously taken with which the temperature deviations in the superheaters, for. B. due to heating faults, can be quickly determined and corrected.

Anhand der Zeichnungen werden im folgenden die Erfindung sowie weitere Ausgestaltungen und Vorteile näher beschrieben und erläutert.The invention and further refinements and advantages are described and explained in more detail below with reference to the drawings.

Es zeigen

  • Figur 1 ein Funktionsschaltbild eines Ausführungsbeispiels,
  • Figur 2 ein Diagramm zum Veranschaulichen der Größe eines ersten in der Anordnung nach Figur 1 verwendeten Divisors,
  • Figur 3 ein Funktionsschaltbild zum Erzeugen des Divisors nach Figur 2,
  • Figur 4 ein Diagramm zum Veranschaulichen der Größe eines in der Anordnung nach Figur 1 verwendeten zweiten Divisors und
  • Figur 5 ein Funktionsschaltbild zum Erzeugen des Divisors nach Figur 4.
Show it
  • FIG. 1 shows a functional circuit diagram of an exemplary embodiment,
  • FIG. 2 shows a diagram to illustrate the size of a first divisor used in the arrangement according to FIG. 1,
  • FIG. 3 shows a functional circuit diagram for generating the divisor according to FIG. 2,
  • Figure 4 is a diagram illustrating the size of a second divisor used in the arrangement of Figure 1 and
  • FIG. 5 shows a functional circuit diagram for generating the divisor according to FIG. 4.

In Figur 1 ist mit KL1 ein erster Kühler bezeichnet, der im Dampfweg eines Dampferzeugers liegt. Auf ihn folgen ein erster Überhitzer UH1, ein zweiter Kühler KL2 und ein zweiter Überhitzer UH2. Die Dampfaustrittstemperatur des Dampferzeugers wird von einem Temperaturmeßumformer MT4 in einen elektrischen Wert umgeformt, der in einem Addierer AD11 mit einem in einem Sollwertgeber SG3 -eingestellten Sollwert verglichen wird. Auf diesen Sollwert wird die Austrittstemperatur des Dampferzeugers geregelt. Die Regeldifferenz wird über einen Dividierer DV2, dessen Bedeutung weiter unten erläutert wird, sowie Addierer AD8, AD7 dem Eingang eines PI-Reglers PIR2 zugeführt, der einen Stellmotor SM2 ansteuert, der ein Einspritzventil EV2 verstellt. Mit diesem wird der Durchfluß des Einspritzwassers in den zweiten Kühler KL2 eingestellt. Der damit geschlossene Regelkreis schließt den zweiten Überhitzer UH2 ein, dessen Austrittstemperatur bei Änderung des Einspritzwasserdurchflusses im Kühler KL2 sich nur langsam entsprechend einem Verzögerungsglied mit Verzugs- und Ausgleichszeit ändert. Es wird daher die Temperatur am Austritt des zweiten Kühlers KL2 ge messen, von einem Umformer MT3 in einen elektrischen Wert umgesetzt und mit einer kleinen Verzugszeit als Hilfsregelgröße verwendet. Im Falle einer Beheizungsstörung, z.B. einer fallenden Dampftemperatur am Ausgang des zweiten Überhitzers UH2, wird das Ausgangssignal des Addierers AD11 positiv und das Ausgangssignal des Addierers AD7 negativ. Über den Regler PIR2 wird der Einspritzwasserdurchfluß verringert, so daß mit steigender Temperatur hinter dem zweiten Kühler KL2 das Ausgangssignal des Addierers AD7 wieder Null wird. In einem Verzögerungsglied VZ2 ist die Verzugs- und Ausgleichszeit des Überhitzers UH2 nachgebildet. Aus der Verzugs- und der Ausgleichszeit des zweiten Überhitzers UH2, die nach Aufschalten einer Sprungfunktion ermittelt werden können, können die Ordnung des Verzögerungsgliedes und die Zeitkonstanten nach bekannten Verfahren ermittelt werden. Sein Ausgangssignal wird vom unverzögerten Signal des Umformers MT3 in einem Addierer AD9 subtrahiert, so daß dessen Ausgangssignal, das durch das Verringern der Einspritzwassermenge verursacht wurde, entgegengesetzt zur Temperaturerhöhung am Austritt des Überhitzers UH2 abklingt. Die Differenz dieser beiden Signale am Addierer AD7 wird Null, so daß über den Regler PIR2 die Einspritzwassermenge nicht mehr verstellt wird.In FIG. 1, KL1 denotes a first cooler that lies in the steam path of a steam generator. It is followed by a first superheater UH1, a second cooler KL2 and a second superheater UH2. The steam outlet temperature of the steam generator is converted into an electrical value by a temperature transmitter MT4, which is compared in an adder AD11 with a setpoint set in a setpoint generator SG3. The outlet temperature of the steam generator is regulated to this setpoint. The control difference is fed via a divider DV2, the meaning of which is explained below, and adders AD8, AD7 to the input of a PI controller PIR2, which controls a servomotor SM2 which adjusts an injection valve EV2. With this the flow of the injection water into the second cooler KL2 is set. The control loop thus closed includes the second superheater UH2, the outlet temperature of which changes only slowly when the injection water flow in the cooler KL2 changes, in accordance with a delay element with delay and compensation time. The temperature at the outlet of the second cooler KL2 is therefore measured, converted into an electrical value by a converter MT3 and used as an auxiliary control variable with a short delay time. In the event of a heating fault, e.g. a falling steam temperature at the output of the second superheater UH2, the output signal of the adder AD11 becomes positive and the output signal of the adder AD7 becomes negative. The injection water flow is reduced via the controller PIR2, so that the output signal of the adder AD7 becomes zero again as the temperature behind the second cooler KL2 increases. The delay and compensation time of the superheater UH2 is simulated in a delay element VZ2. The order of the delay element and the time constants can be determined by known methods from the delay time and the equalization time of the second superheater UH2, which can be determined after a step function has been applied. Its output signal is subtracted from the undelayed signal of the converter MT3 in an adder AD9, so that its output signal, which was caused by the reduction in the quantity of injection water, decays in the opposite direction to the temperature increase at the outlet of the superheater UH2. The difference between these two signals at the adder AD7 becomes zero, so that the quantity of injection water is no longer adjusted via the controller PIR2.

Wie schon erwähnt, verhalten sich die Überhitzer UH1, UH2 wie ein Verzögerungsglied höherer Ordnung mit einer Verzugszeit und einer Ausgleichszeit. Das Verhältnis von Verzugs- zu Ausgleichszeit kann als unabhängig vom Dampfdurchsatz angenommen werden. Die Zeiten selbst sind jedoch etwa umgekehrt proportional zum Dampfstrom bzw. zur Last, so daß sie sich z. B. bei halber Last gegenüber Vollast verdoppeln. Dies wird im Verzögerungsglied VZ2 dadurch berücksichtigt, daß der Dampfstrom von einem Durchflußmeßumformer MV erfaßt wird und in einer Einheit KW2 ein dem Kehrwert des Durchflusses proportionales Signal gebildet wird, mit dem die Zeitkonstanten des Verzögerungsgliedes VZ2 derart beeinflußt werden, daß sie umgekehrt proportional zum Dampfdurchfluß sind.As already mentioned, the superheaters UH1, UH2 behave like a higher-order delay element with a delay time and an equalization time. The ratio of delay to compensation time can be assumed to be independent of the steam throughput. However, the times themselves are approximately inversely proportional to the steam flow or the load, so that they are z. B. double at half load compared to full load. This is taken into account in the delay element VZ2 in that the steam flow is detected by a flow transmitter MV and in a unit KW2 a signal proportional to the reciprocal of the flow is formed, with which the time constants of the delay element VZ2 are influenced such that they are inversely proportional to the steam flow.

Zum Ausgangssignal des Verzögerungsgliedes VZ2, das der verzögerten Temperatur am Ausgang des zweiten Kühlers KL2 entspricht, wird in einem Addierer AD6 der in einem Sollwertgeber SG1 eingestellte Sollwert für die Temperaturdifferenz am Kühler KL2 addiert. Das Ausgangssignal des Addierers AD6 gelangt über eine Minimalwertauswahl MIN auf einen Addierer AD5, der es mit dem Ausgangssignal eines Temperaturumformers MT2 vergleicht. Die Regeldifferenz, die der Abweichung der Temperaturdifferenz am zweiten Kühler KL2 von dem im Sollwertgeber SG1 eingestellten Sollwert entspricht, gelangt über einen Dividierer DV1 sowie Addierer AD3, AD2 auf den Eingang eines PI-Reglers PIR1, der einen Stellmotor SM1 mit einem Einspritzventil EV1 ansteuert. Mit diesem wird die Einspritzmenge des Speisewassers in den ersten Kühler KL1 eingestellt, derart, daß die Temperaturdifferenz am zweiten Kühler KL2 gleich dem mit dem Sollwertgeber SG1 eingestellten Sollwert ist. Da als Signal für die Temperatur hinter dem zweiten Kühler KL2 das Ausgangssignal des Verzögerungsgliedes VZ2 verwendet wird, sind die Temperaturregelungen dynamisch entkoppelt. Durch diese Entkopplung wird vermieden, daß bei einer Verstellung der Einspritzung in den zweiten Kühler KL2 sofort der Regler PIR1 mit der Änderung der Einspritzung in den Kühler KL1 angeregt wird, was eine Pendelung auslösen könnte.To the output signal of the delay element VZ2, which corresponds to the delayed temperature at the output of the second cooler KL2, the setpoint for the temperature difference at the cooler KL2 set in a setpoint generator SG1 is added in an adder AD6. Via a minimum value selection MIN, the output signal of the adder AD6 arrives at an adder AD5, which compares it with the output signal of a temperature converter MT2. The control difference, which corresponds to the deviation of the temperature difference at the second cooler KL2 from the setpoint set in the setpoint generator SG1, passes via a divider DV1 and adder AD3, AD2 to the input of a PI controller PIR1, which controls a servomotor SM1 with an injection valve EV1. With this the injection quantity of the feed water into the first cooler KL1 is set in such a way that the temperature difference at the second cooler KL2 is equal to the setpoint value set with the setpoint generator SG1. Since the output signal of the delay element VZ2 is used as the signal for the temperature behind the second cooler KL2, the temperature controls are dynamically decoupled. This decoupling prevents that when the injection in the second cooler KL2 is adjusted, the controller PIR1 is immediately excited with the change in the injection into the cooler KL1, which could trigger an oscillation.

Überschreitet das Ausgangssignal des Addierers AD6 einen vorgegebenen Grenzwert, der mit einem Sollwertgeber SG2 eingestellt ist, schaltet die Minimalwertauswahl MIN anstatt des Ausgangssignals des Addierers AD6 den Grenzwert vom Sollwertgeber SG2 auf den Addierer AD5, so daß die Temperatur vor dem zweiten Kühler KL2 auf dem Grenzwert gehalten wird.If the output signal of the adder AD6 exceeds a predetermined limit value which is set with a setpoint generator SG2, the minimum value selection MIN switches the limit value from the setpoint generator SG2 to the adder AD5 instead of the output signal of the adder AD6, so that the temperature upstream of the second cooler KL2 is at the limit value is held.

Im Prinzip arbeitet die Regelung mit dem Regler PIR1 entsprechend der mit dem Regler PIR2. Ein Unterschied besteht darin, daß als Hilfsregelgröße nicht die Temperatur nach dem Kühler KL1, sondern die Enthalpie verwendet wird. Hierzu werden mit den Meßumformern MT1, MP1 Temperatur und Druck nach dem Kühler KL1 erfaßt und einem an sich bekannten Enthalpie-Rechner ER zugeführt. Dessen Ausgangssignal wird direkt über ein Verzögerungsglied VZ1, in dem die Verzögerung durch den Überhitzer UH1 nachgebildet ist, einem Addierer AD1 zugeführt. Dieses Verzögerungsglied ist im allgemeinen von höherer Ordnung, evtl. sogar mit unterschiedlichen Zeitkonstanten mit einer Verzugszeit und einer Ausgleichszeit. Die im Addierer AD1 gebildete Differenz der beiden Signale wird dem PI-Regler P)R1 aufgeschaltet. Da die Verzögerung des Dampferzeugers UH1 umgekehrt proportional zum Dampfdurchsatz ist, wird in einer Einheit KW1 ein Signal erzeugt, das zum Dampfdurchsatz umgekehrt proportional ist, und mit diesem Signal die Zeitkonstanten des Verzögerungsgliedes VZ1 beeinflußt. Die Verwendung der Enthalpie anstatt der Temperatur als Hilfsregelgröße ist deshalb vorteilhaft, weil am Ausgang des ersten Kühlers KL1 der Dampf nahe dem Sättigungsbereich und damit der Zusammenhang zwischen Temperatur am Austritt des ersten Überhitzers UH1 und der Temperatur hinter dem ersten Kühler KL1 stark nichtlinear sein kann.In principle, the control works with the controller PIR1 in accordance with that with the controller PIR2. One difference is that not the temperature after the cooler KL1, but the enthalpy is used as the auxiliary control variable. For this purpose, the temperature and pressure downstream of the cooler KL1 are recorded with the transmitters MT1, MP1 and fed to an enthalpy computer ER known per se. Its output signal is fed directly to an adder AD1 via a delay element VZ1, in which the delay is simulated by the superheater UH1. This delay element is generally of a higher order, possibly even with different time constants with a delay time and an equalization time. The difference between the two signals formed in the adder AD1 is applied to the PI controller P) R1. Since the delay of the steam generator UH1 is inversely proportional to the steam throughput, a signal is generated in a unit KW1, which is inversely proportional to the steam throughput, and with this signal influences the time constants of the delay element VZ1. The use of the enthalpy instead of the temperature as an auxiliary control variable is advantageous because at the outlet of the first cooler KL1 the steam near the saturation area and thus the relationship between the temperature at the outlet of the first superheater UH1 and the temperature behind the first cooler KL1 can be strongly non-linear.

Mit den Dividierern DV1, DV2 wird die Regelung an die in Abhängigkeit des Dampfdruckes veränderliche Verstärkung der Regelstrecke angepaßt. Auch bei gleichbleibender Heizleistung der Uberhitzer ändert sich nämlich die Austrittstemperatur nicht um denselben Betrag wie die Eintrittstemperatur. Um diese Veränderung der Verstärkung der Regelstrecke zu berücksichtigen, wird mit dem Druckumformer MP3 der Druck am Ausgang des Überhitzers UH2 erfaßt und einem Funktionsgenerator FG2 zugeführt.With the dividers DV1, DV2, the control is adapted to the variable gain of the controlled system depending on the vapor pressure. Even if the superheater's heating output remains the same, the outlet temperature does not change by the same amount as the inlet temperature. In order to take this change in the gain of the controlled system into account, the pressure at the output of the superheater UH2 is detected with the pressure converter MP3 and fed to a function generator FG2.

Das Diagramm in Figur 2 zeigt, welche Werte der Divisor DIV2 zur korrekten Kompensation der Regelstreckenverstärkung im Überhitzer UH2 in Abhängigkeit des Druckes P am Austritt des Überhitzers UH2 und der Temperatur an dessen Eintritt haben sollte.The diagram in FIG. 2 shows which values the divisor DIV2 should have for correct compensation of the controlled system gain in the superheater UH2 as a function of the pressure P at the outlet of the superheater UH2 and the temperature at its entry.

Figur 3 zeigt als Funktionsblockbild, wie der Divisor für den Dividierer DV2 einfach erzeugt werden kann. Zur Verringerung des Aufwandes ist darauf verzichtet, die vollständige in Figur 2 gezeigte Kurvenschar zu erzeugen, sondern es wird die Temperatur unberücksichtigt gelassen und lediglich eine mittlere Gerade erzeugt. Dies reicht in der Praxis völlig aus, da die Abweichung vom korrekten Wert maximal 10% beträgt.FIG. 3 shows as a functional block diagram how the divisor for the divider DV2 can easily be generated. In order to reduce the effort, it is not necessary to generate the complete family of curves shown in FIG. 2, instead the temperature is ignored and only a middle straight line is generated. In practice, this is completely sufficient, since the deviation from the correct value is a maximum of 10%.

Der Funktionsgeber FG2 nach Figur 3 enthält einen Konstantengeber KG7, der auf einen einem Druck von 70 bar entsprechenden Wert eingestellt ist. Dieser Wert wird mit dem Ausgangssignal des Druckumformers MP3 in einem Addierer AD16 verglichen und die Differenz dem einen Eingang einer Maximalwertauswahl MAX zugeführt. An deren anderem Eingang liegt der Wert Null. Ist der vom Druckumformer MP3 erfaßte Druck kleiner als 70 bar, wird der Wert Null zu einem Multiplizierer M7 durchgeschaltet, dessen Ausgangswert daher ebenfalls Null ist. Das Ausgangssignal eines Addierers AD17, das den Divisor für den Dividierer DV2 darstellt, ist daher der in einem Konstantengeber KG9 eingestellte Wert, der entsprechend Figur 2 auf 1,02 eingestellt ist. Mit steigendem Druck wird das Ausgangssignal des Addierers AD16 und damit das der Maximalwertauswahl MAX positiv und vom Multiplizierer M7 mit einem in einem Konstantengeber KG8 eingestellten Faktor multipliziert. Dieser Faktor ist so gewählt, daß der Divisor für den Dividierer DV2 etwa gleich dem für 470 °C (Figur 2) ist. Selbstverständlich könnte anstelle des Konstantengebers KG8 eine Schaltung verwendet werden, deren Ausgangssignal sich in Abhängigkeit der Temperatur so ändert, daß die in Figur 2 eingetragene Kurvenschar erzielt wird.The function transmitter FG2 according to FIG. 3 contains a constant transmitter KG7, which is set to a value corresponding to a pressure of 70 bar. This value is compared with the output signal of the pressure transducer MP3 in an adder AD16 and the difference is fed to one input of a maximum value selection MAX. At the other input there is a value of zero. If the pressure detected by the pressure transducer MP3 is less than 70 bar, the value zero is switched through to a multiplier M7, the output value of which is therefore also zero. The output signal of an adder AD17, which represents the divisor for the divider DV2, is therefore the value set in a constant encoder KG9, which is set to 1.02 in accordance with FIG. With increasing pressure, the output signal of the adder AD16 and thus that of the maximum value selection MAX is positive and multiplied by the multiplier M7 by a factor set in a constant encoder KG8. This factor is chosen so that the divisor for the divider DV2 is approximately equal to that for 470 ° C (Figure 2). Of course, instead of the constant encoder KG8, a circuit could be used whose output signal changes depending on the temperature so that the family of curves shown in FIG. 2 is achieved.

Auch am Überhitzer UH1 ist bei konstanter Heizleistung die Temperaturdifferenz vom Druck abhängig. Diese Abhängigkeit der Regelstreckenverstärkung wird durch Division der Regeldifferenz am Ausgang des Addierers AD5 durch einen druck-und temperaturabhängigen Wert, der in einem Funktionsgeber FG1 gebildet wird, kompensiert. Die druck- und temperaturabhängigen Divisorwerte DIV1 sind in Figur 4 dargestellt.The temperature difference on the superheater UH1 also depends on the pressure with constant heating output. This dependence on the controlled system gain is compensated for by dividing the control difference at the output of the adder AD5 by a pressure and temperature-dependent value which is formed in a function generator FG1. The pressure and temperature dependent divisor values DIV1 are shown in FIG. 4.

Figur 5 zeigt Einzelheiten des Funktionsgebers FG1. Die vom Druckumformer MP2 gelieferten Werte werden in einem Addierer AD18 mit einem Wert verglichen, der einem Druck von 30 bar entspricht und in einem Konstantengeber KG10 eingestellt ist. Die Differenz wird von einem Multiplizierer M8 mit einem von einem Konstantengeber KG11 gelieferten Faktor multipliziert. Das Ergebnis wird in einem Multiplizierer M9 mit einer in einem Addierer AD20 gebildeten Differenz multipliziert und in einem Addierer AD21 von dem von einem Konstantengeber KG13 erzeugten Wert 1,86 subtrahiert. Das Ergebnis wird als Divisor dem Dividierer DV1 zugeführt. Ein Addierer AD19 bildet die Differenz zwischen dem vom Temperaturumformer MT2 abgegebenen Signal und dem in einem Konstantengeber KG14 eingestellten, einer Temperatur von 440° entsprechenden Wert. Die Differenz wird über einen Funktionsgeber FG3, der die in Figur 4 ersichtliche nichtlineare Abhängigkeit des Divisors von der Temperatur erzeugt, einem Addierer AD20 zugeführt, der das Ausgangssignal des Funktionsgebers FG3 von einem in einem Konstantengeber KG12 eingestellten Wert, dem Wert Eins, subtrahiert. Der Funktionsgenerator FG3 ist so ausgebildet, daß sein Ausgangssignal beim Eingangssignal Null, entsprechend 440°, ebenfalls Null ist und daß mit zunehmender Temperatur sein Ausgangssignal nichtlinear zunimmt, derart, daß es bei 465° etwa den Wert 0,14 und bei 490° einen Wert von etwa 0,24 hat. Der dem Multiplizierer M9 zugeführte Faktor ist daher bei 440° Eins und sinkt mit steigender Temperatur nichtlinear auf etwa 0,76 ab.Figure 5 shows details of the function generator FG1. The values supplied by the pressure transmitter MP2 are compared in an adder AD18 with a value which corresponds to a pressure of 30 bar and is set in a constant encoder KG10. The difference is multiplied by a multiplier M8 by a factor supplied by a constant encoder KG11. The result is multiplied in a multiplier M9 by a difference formed in an adder AD20 and subtracted in an adder AD21 from the value 1.86 generated by a constant encoder KG13. The result is fed to the divider DV1 as a divisor. An adder AD19 forms the difference between the signal emitted by the temperature converter MT2 and the value set in a constant encoder KG14, which corresponds to a temperature of 440 ° . The difference is fed via a function generator FG3, which generates the non-linear dependence of the divisor on the temperature shown in FIG. 4, to an adder AD20, which subtracts the output signal of the function generator FG3 from a value set in a constant generator KG12, the value one. The function generator FG3 is designed such that its output signal is zero when the input signal is zero, corresponding to 440 ° , and that its output signal increases nonlinearly with increasing temperature, such that it is approximately 0.14 at 465 ° and a value at 490 ° of about 0.24. The factor fed to the multiplier M9 is therefore at 440 ° one and decreases nonlinearly to approximately 0.76 with increasing temperature.

Beträgt der Dampfdruck 30 bar, ist das Ausgangssignal des Addierers AD18 Null, und der Divisor ist der im Konstantengeber KG13 eingestellte Wert 1,86. Steigt bei konstant 440 °C der Druck an, nimmt das Ausgangssignal des Multiplizierers M8 zu und wird, da es im Multiplizierer M9 wegen der Multiplikation mit Eins nicht verändert wird, im Addierer AD21 vom Wert 1,86 subtrahiert. Der Divisor ändert sich daher mit steigendem Druck entsprechend der in Figur 4 mit 440° bezeichneten Geraden. Mit steigender Temperatur wird der vom Addierer AD20 dem Multiplizierer M9 zugeführte Faktor kleiner und damit auch der dem Addierer AD21 zugeführte Subtrahend, so daß der Divisor DIV1 bei konstantem Druck entsprechend den in Figur 4 gezeigten Diagrammen ansteigt. Werden geringere Ansprüche an die Regelgenauigkeit gestellt, kann auf den Multiplizierer M9 und die den Korrekturfaktor bildende Schaltung verzichtet werden. Der Konstantengeber KG11 wird dann zweckmäßig auf einen solchen Wert eingestellt, daß der Divisor bei Änderung des Druckes einer mittleren der in Figur 4 gezeigten Geraden folgt. Eine solche Gerade ist z. B. die für 460°.If the steam pressure is 30 bar, the output signal of the adder AD18 is zero and the divisor is the value 1.86 set in the constant encoder KG13. If the pressure rises at a constant 440 ° C., the output signal of the multiplier M8 increases and, since it is not changed in the multiplier M9 because of the multiplication by one, is subtracted from the value 1.86 in the adder AD21. The divisor therefore changes with increasing pressure in accordance with the straight line labeled 440 ° in FIG. As the temperature rises, the factor supplied by the adder AD20 to the multiplier M9 becomes smaller and thus also the subtrahend supplied to the adder AD21, so that the divisor DIV1 rises at constant pressure in accordance with the diagrams shown in FIG. If lower demands are placed on the control accuracy, the multiplier M9 and the circuit forming the correction factor can be dispensed with. The constant encoder KG11 is then expediently set to such a value that the divisor follows a middle line shown in FIG. 4 when the pressure changes. Such a straight line is e.g. B. for 460 ° .

Der bisher beschriebene Regler zeigt zwar wegen der Entkopplung der beiden Regelkreise eine sehr gute Stabilität; wegen der langen Verzugs-und Ausgleichszeiten der Überhitzer werden jedoch, wenn die Temperaturen ausschließlich am Austritt der Überhitzer ermittelt werden, die Störungen erst nach relativ langer Verzögerungszeit festgestellt. Zum raschen Feststellen von Beheizungsstörungen sind in der Anordnung nach Figur 1 zwei Störungsermittlungsschaltungen STM1, STM2 enthalten. Für diese ist von der Überlegung ausgegangen, daß jeder Überhitzer durch ein Modell mit mehreren, z. B. vier, hintereinandergeschalteten Verzögerungsgliedern nachgebildet werden kann. Da am Überhitzer nur die Ein- und Austrittstemperaturen gemessen werden, ist am Modell nur das Eingangssignal des ersten und das Ausgangssignal . des letzten Verzögerungsgliedes bekannt. Damit im Falle einer Störung deren Auswirkung frühzeitig erkannt wird, genügt es, wenn die Temperaturänderung in etwa der Mitte des Überhitzers ermittelt wird. Die im Dividierer DV2 korrigierte Regeldifferenz ist einem Addierer AD12 zugeführt. In einer Rückkopplungsschleife liegt ein Differenzierglied DG1, dessen Zeitkonstante gleich der des letzten Verzögerungsgliedes des Modells für den Überhitzer UH2 ist. Die Wirkung des Di fferenziergliedes kann durch Multiplikation des rückgeführten Signals mit einem Konstantengeber KG1 eingestellt werden. Damit steht am Ausgang des Addierers AD12 ein Signal zur Verfügung, das dem Eingang des letzten Verzögerungsgliedes des Überhitzermodells entspricht. Aus diesem Signal wird mit einem Addierer AD13, einem Multiplizierer M2 mit einem Konstantengeber KG2 und einem Differenzierglied DG2 das Ausgangssignal des vorletzten Verzögerungsgliedes des Uberhitzermodells ermittelt. Unter der Annahme, daß das Modell aus vier hintereinandergeschalteten Verzögerungsgliedern besteht, steht somit ein Signal zur Verfügung, das der Temperaturänderung in der Mitte des Überhitzers entspricht. Die Geschwindigkeit, mit der die Eingangssignale der beiden letzten Verzögerungsglieder ermittelt werden, kann mit den Konstantengebern KG1, KG2 an den Eingängen der Differenzierglieder DG1, DG2 gewählt werden. Die Zeitkonstanten der Differenzierglieder stimmen mit denen der Verzögerungsglieder überein; sie werden daher auch mit dem Kehrwert des Dampfdurchflusses verändert.The controller described so far shows very good stability because of the decoupling of the two control loops; Because of the long delay and compensation times of the superheaters, however, if the temperatures are determined exclusively at the outlet of the superheaters, the faults are only determined after a relatively long delay time. For the rapid detection of heating faults, the arrangement according to FIG. 1 contains two fault detection circuits STM1, STM2. For these, it is assumed that each superheater has a model with several, e.g. B. four, series-connected delay elements can be simulated. Since only the inlet and outlet temperatures are measured on the superheater, only the input signal of the first and the output signal is on the model. of the last delay element known. So that in the event of a malfunction the effects of which are recognized at an early stage, it is sufficient if the temperature change is determined approximately in the middle of the superheater. The control difference corrected in the divider DV2 is fed to an adder AD12. In a feedback loop there is a differentiating element DG1, the time constant of which is equal to that of the last delay element of the model for the superheater UH2. The effect of the differentiating element can be adjusted by multiplying the returned signal by a constant encoder KG1. A signal is thus available at the output of the adder AD12 which corresponds to the input of the last delay element of the superheater model. The output signal of the penultimate delay element of the superheater model is determined from this signal with an adder AD13, a multiplier M2 with a constant encoder KG2 and a differentiator DG2. Assuming that the model consists of four delay elements connected in series, a signal is available which corresponds to the temperature change in the middle of the superheater. The speed at which the input signals of the last two delay elements are determined can be selected with the constant encoders KG1, KG2 at the inputs of the differentiators DG1, DG2. The time constants of the differentiators match those of the delay elements; they are therefore also changed with the reciprocal of the steam flow.

Das Ausgangssignal des Addierers AD13 wird auf ein Differenzierglied DG3 mit der gleichen Zeitkonstanten wie die anderen Differenzier- und Verzögerungsglieder gegeben. Damit wird ein Vorhalt für die Regelung erzeugt, dessen Größe von der Ordnungszahl der Regelstrecke abhängig und an einem Konstantengeber KG3 eingestellt werden kann. Da durch die Regelung die Temperatur hinter dem zweiten Kühler KL2 verändert wird, damit bei gleichbleibender Störung die Temperatur am Austritt des Überhitzers den Sollwert erreicht, wird das mit dem Verzögerungsglied VZ2 verzögerte Ausgangssignal des Temperaturumformers MT3 über den Addierer AD10 auf den Eingang der Störungsermittlungsschaltung STM2 aufgeschaltet. Dadurch wird erreicht, daß deren Eingangssignal entsprechend der Störung auf dem neuen Wert des verzögerten Signals der Temperatur hinter dem zweiten Kühler KL2 stehenbleibt und nicht entsprechend der Regeldifferenz am Ausgang des Addierers AD11 auf Null zurückgeht. Somit wird das Ausgangssignal der Störungsermittlungsschaltung, ohne die Polarität zu wechseln, auf Null zuruckgehen.The output signal of the adder AD13 is applied to a differentiating element DG3 with the same time constant as the other differentiating and delay elements. This creates a reserve for the control, the size of which depends on the ordinal number of the controlled system and can be set on a constant encoder KG3. Since the temperature behind the second cooler KL2 is changed by the control so that the temperature at the outlet of the superheater reaches the setpoint with a constant fault, the output signal of the temperature converter MT3 delayed by the delay element VZ2 is connected to the input of the fault determination circuit STM2 via the adder AD10 . This ensures that their input signal remains at the new value of the delayed temperature signal behind the second cooler KL2 in accordance with the fault and does not decrease to zero in accordance with the control difference at the output of the adder AD11. Thus, the output of the fault detection circuit will return to zero without changing polarity.

Die zweite Störungsermittlungsschaltung STM2 arbeitet in gleicher Weise wie die erste STM1. Ihre Beschreibung erübrigt sich daher.The second fault detection circuit STM2 works in the same way as the first STM1. Your description is therefore unnecessary.

Die Anwendung der beschriebenen Art der Störungsermittlung ist nicht nur bei Wärmekraftwerken, sondern bei allen Regelstrecken mit Langzeitverhalten sinnvoll, also z. B. auch bei Sichtertemperaturregelungen in Mühlen oder bei der Feuchteregelung an Papiermaschinen.The use of the described type of malfunction determination is not only useful for thermal power plants, but for all controlled systems with long-term behavior. B. also in classifier temperature control in mills or in moisture control on paper machines.

Das Ausführungsbeispiel ist in den Figuren 1, 3 und 5 nach Art eines Schaltbildes dargestellt und wurde auch so der Verständlichkeit halber beschrieben. Tatsächlich wird man das Ausführungsbeispiel mit Ausnahme der Kühler, Überhitzer und Meßumformer mit einem programmierbaren Rechner realisieren. Gleiches gilt für alle im Rahmen der Erfindung liegenden Ausgestaltungen.The exemplary embodiment is shown in FIGS. 1, 3 and 5 in the manner of a circuit diagram and has also been described for the sake of clarity. In fact, with the exception of the cooler, superheater and transmitter, the exemplary embodiment will be implemented with a programmable computer. The same applies to all configurations within the scope of the invention.

Claims (12)

1. Device for regulating the exit vapour temperature of a vapour generator which contains, situated one behind the other in the vapour stream, a first cooler (KL1), a first superheater (UH1), a second cooler (KL2) and a second superheater (UH2), with a regulator (PIR1) controlling the first cooler (KL1) and a second regulator (PIR2) controlling the second cooler (KL2), characterised in that a signal corresponding to the temperature difference at the second cooler (KL2) is compared with a setpoint value (SG1) and the result of the comparison is applied as the deviation to the first regulator (PIR1), and that a signal corresponding to the exit temperature of the vapour generator is compared with a setpoint value (SG3) and the result of the comparison is applied as the deviation to the second regulator (PIR2).
2. The device according to claim 1, characterised in that the temperature at the entrance of the second cooler (KL2) is restricted to a limiting value (SG2).
3. The device according to claim 1 or 2, characterised in that a signal corresponding to the temperature at the exit of the first cooler (KL1) or a signal derived therefrom is passed via a first time-delay element (VZI), the time constants of which are the same as those of the first superheater (UH1), that the difference between the output signal from the first time-delay element (VZ1) and the signal corresponding to the temperature at the exit of the first cooler (KL1), or alternatively the signal derived therefrom, is formed and applied to the first regulator (PIR1), which controls the flow of the feed water fed into the first cooler (KL1).
4. The device according to claim 3, characterised in that the signal derived from the temperature at the exit of the cooler (KL1) is a signal corresponding to enthalpy.
5. The device according to one of claims 1 to 4, characterised in that a signal corresponding to the temperature at the exit of the second cooler (KL2) is passed via a second time-delay element (VZ2) whose time constant is the same as that of the second superheater (UH2), and that the difference between the output signal from the second time-delay element (VZ2) and the signal corresponding to the temperature is formed and applied to the second regulator (PIR2), which controls the flow of the feed water injected into the second cooler (KL2).
6. The device according to one of claims 3 to 5, characterised in that the time constants of the timedelay elements (VZ1, VZ2) are inversely proportional to the vapour flow rate.
7. The device according to one of claims 3 to 6, characterised in that the difference between the output signal from the second time-delay element (VZ2) and the signal corresponding to the temperature at the entrance of the second cooler (KL2) is compared with the setpoint value (SG1) of the temperature difference at the second cooler (KL2) and applied as the deviation to the first regulator (PIR1).
8. The device according to one of claims 1 to 7, characterised by correcting the deviation in temperature at the vapour generator outlet and/or at the entrance of the second cooler (KL2) in response to vapour pressure, so as to compensate the response of the temperature change in the superheater to the vapour pressure.
9. The device according to claim 8, characterised by correcting the deviation in response to the enthalpy of the vapour at the superheater outlet.
10. The device according to one of claims 1 to 9, characterised in that the temperatures at the exits of the superheaters (UH1, UH2) are fed via differentiating elements (DG1, DG2, DG3) to the respective regulator (PIR2 or PIR1), downstream of which is disposed the cooler (KL1, KL2) situated before the respective superheater (UH1, UH2).
11. The device according to claim 10, characterised in that for each superheater there is a fault de- . tection circuit (STM1, STM2), which contains a first differentiating element (DG1), the time constant of which is the same as that of the last time-delay element of the superheater model; which circuit contains a second differentiating element (DG2) disposed downstream of the first differentiating element (DG1) and the time constant of which is the same as that of the penultimate time-delay element of the superheater model, etc., the number of differentiating elements (DG1, DG2) being approximately half the ordinal number of the superheater model, and in that disposed downstream of the last differentiating element is a derivative action unit (DG3) whose output signal is applied to the regulator (PIR2).
12. The device according to claim 11, characterised in that the output signals from the time-delay elements (VZ1, VZ2) are applied to the inputs of the fault detection circuits (STM1, STM2).
EP87710014A 1986-09-15 1987-09-15 Vapour temperature regulation device for a vapour generator Expired - Lifetime EP0263056B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT87710014T ATE50853T1 (en) 1986-09-15 1987-09-15 ARRANGEMENT FOR CONTROLLING THE STEAM TEMPERATURE OF A STEAM GENERATOR.

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Application Number Priority Date Filing Date Title
DE3631386 1986-09-15
DE3631386 1986-09-15

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EP0263056A1 EP0263056A1 (en) 1988-04-06
EP0263056B1 true EP0263056B1 (en) 1990-03-07

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EP87710014A Expired - Lifetime EP0263056B1 (en) 1986-09-15 1987-09-15 Vapour temperature regulation device for a vapour generator

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DE19901656A1 (en) 1999-01-18 2000-07-20 Abb Alstom Power Ch Ag Regulating temp. at outlet of steam superheater involves spraying water into superheater near steam inlet; water can be sprayed into wet, saturated or superheated steam

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Publication number Priority date Publication date Assignee Title
FR1402362A (en) * 1964-07-23 1965-06-11 Siemens Ag Intermediate superheated steam boiler
DE3121442A1 (en) * 1981-05-29 1983-01-05 Steag Ag, 4300 Essen Method for controlling the temperature of steam flowing in a line by injection, and arrangement for implementing the method

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