EP0643816B1 - Process and device for regulating the flue gas temperature at the outlet of a steam generator - Google Patents

Process and device for regulating the flue gas temperature at the outlet of a steam generator Download PDF

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Publication number
EP0643816B1
EP0643816B1 EP93907804A EP93907804A EP0643816B1 EP 0643816 B1 EP0643816 B1 EP 0643816B1 EP 93907804 A EP93907804 A EP 93907804A EP 93907804 A EP93907804 A EP 93907804A EP 0643816 B1 EP0643816 B1 EP 0643816B1
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EP
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Prior art keywords
flue gas
gas temperature
steam generator
heating surface
sections
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EP93907804A
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German (de)
French (fr)
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EP0643816B2 (en
EP0643816A1 (en
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Georg Lösel
Reiner Engelhardt
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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
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/02—Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways
    • F22D1/12—Control devices, e.g. for regulating steam temperature

Definitions

  • the invention relates to a method and a device for adjusting the flue gas temperature at the outlet of a steam generator used in a smoldering furnace, which has a heating surface that can be used for heat transfer between the flue gas and the feed water, and which is followed by a cleaning system on the flue gas side.
  • steam is converted, e.g. by indirect heat exchange between hot flue gas and feed water, which is conducted in a water-steam cycle. generated for a steam turbine.
  • the flue gas is generated by burning a fossil fuel in a combustion chamber of the smoldering furnace (EP-PS 0 340 537).
  • the feed water flows inside the steam generator along a heating surface usually in the form of tubes or tube bundles and absorbs heat from the flue gas.
  • the cooled flue gas is first cleaned when it leaves the steam generator and then released into the environment via a chimney.
  • the scrubbing liquid mixed with the reaction products is evaporated by means of the flue gas leaving the steam generator, the dried reaction products being separated off.
  • the flue gas temperature at the entrance to the cleaning system must not fall below a predetermined value.
  • the flue gas temperature at the outlet of the steam generator is usually as low as possible at full load the minimum permissible flue gas temperature for the cleaning system. During part-load operation, however, the flue gas temperature drops, so that there is a risk of malfunction in the cleaning system without special measures. It is therefore necessary to adjust or regulate the flue gas temperature at the outlet of the steam generator, particularly in the case of partial load operation.
  • the fuel is burned with an increased excess of air, so that the heat transfer is shifted into the convection train of the steam generator and the flue gas temperature rises at the outlet of the steam generator.
  • the disadvantage here is the loss of usable heat due to the increased volume flow of the flue gas.
  • a part of the hot flue gas is mixed with the cooled flue gas bypassing the heating surface at the outlet of the steam generator, so that a predetermined flue gas temperature can be maintained.
  • the disadvantage here is the provision of a voluminous flue gas bypass.
  • temperature control is extremely difficult due to strands forming during the mixing.
  • the feed water is preheated before it enters the steam generator by indirect heat exchange with steam, which is taken from the water-steam circuit of the steam turbine.
  • steam which is taken from the water-steam circuit of the steam turbine.
  • the invention is therefore based on the object of specifying a particularly simple method for setting the flue gas temperature.
  • the method is intended to be suitable for control in which a reduction in the flue gas temperature at the outlet of the steam generator takes place simultaneously Entry of a cleaning system is safely avoided below a minimum value.
  • the simplest possible device is to be specified with which a high overall efficiency can be achieved.
  • this object is achieved according to the invention in that the heating surface which is effectively used for heat transfer is changed as a function of the flue gas temperature, with the flue gas temperature deviating from a setpoint above the minimum permissible flue gas temperature for flue gas cleaning, arranged in succession in the flow direction of the feed water Sections of the heating surface can be switched on or off.
  • the object is achieved in that the heating surface used by the flowing feed water can be controlled as a function of the flue gas temperature, the heating surface comprising a number of sections which can be switched on or off individually, which are arranged one behind the other in the flow direction of the flue gas and from the feed water in Flow in the opposite direction one after the other.
  • Each section can be connected on the input side to an actuator.
  • each section can be conveniently located at the entrance have an inlet collector for collecting feed water.
  • the device advantageously comprises a controller connected on the output side to at least one actuator, the input variable of which is the actual value of the flue gas temperature.
  • the steam generator 1 shown in Figure 1 is e.g. Part of a smoldering and burning plant, not shown in detail. It comprises a combustion chamber 2, which is followed by a waste heat boiler 4 via a flue gas duct 3. Inside the waste heat boiler 4 there are heating surfaces 5 in the form of tubes or tube bundles, e.g. hanging, arranged.
  • the steam generator 1 is connected on the output side to a cleaning system 7 via a flue gas line 6.
  • the cleaning system 7 comprises a spray dryer 8, which is followed by a separator 9, for example an electric filter, and a wet cleaner 10.
  • the wet cleaner 10 is connected to the spray dryer 8 via a line 11.
  • the flue gas line 6 opens into a chimney 12 behind the cleaning system 7.
  • a temperature sensor 13 At the outlet of the steam generator 1, a temperature sensor 13 is provided, which is connected to a controller 14.
  • the controller 14 is connected on the output side to a number of actuators, designated as a whole by 15, in the form of valves 15a, 15b, 15c (FIG. 2).
  • the actuators 15 influence the distribution of the feed water S entering the steam generator 1 via a line 30 to an economizer heating surface which serves to preheat the feed water S.
  • the flue gas R generated in the combustion chamber 2 is guided through the steam generator 1 along the arrows shown. In this case, heat is transferred from the hot flue gas R via the heating surfaces 5 to the feed water S flowing in a water-steam cycle (not shown) of a steam turbine.
  • the cooled flue gas R leaving the steam generator 1 is cleaned in the cleaning system 7.
  • the flue gas temperature T i at the outlet of the steam generator 1 is still approximately 220 ° C. at full load.
  • the cleaning takes place within the wet cleaner 10 by means of a washing liquid which contains alkaline components, for example sodium hydroxide.
  • the alkaline constituents essentially form salts with the acidic, for example chlorine-containing substances contained in the flue gas R as reaction products.
  • the washing liquid is fed to the spray dryer 8 together with the reaction products via line 11. There the washing liquid is evaporated by contact with the flue gas R.
  • the reaction products dried at the same time as the evaporation, ie essentially the salts, are separated in the filter 9.
  • the flue gas R is cooled in the cleaning system 7 to a temperature of about 70 ° C.
  • each economizer heating surface 5 used to preheat the feed water S is divided into a number of sections lying one behind the other, preferably into three sections 20 to 22.
  • Each of the sections 20, 21 and 22 is connected to a collector 23, 24, 25 and 26 both on the input side and on the output side.
  • each of the sections 20 to 22 is connected to one of the valves 15a, 15b and 15c via the inlet manifolds 23, 24, 25.
  • the valves 15a, 15b, 15c are connected to a common feed water line 30.
  • the collector 26 is connected via a line 31 in a manner not shown to the other heating surfaces 5 of the steam generator 1.
  • the feed water S is conducted in counterflow to the direction of flow of the flue gas R through meandering tube bundles 35, the walls of which form the heating surface 5.
  • the flue gas R is cooled, the valve 15a first being open and the valves 15b and 15c being closed.
  • the flue gas temperature T i drops at the outlet of the steam generator 1, the heating surface 5 effectively used for heat transfer is reduced.
  • valve 15b is first opened and valve 15a is closed.
  • the valve 15c then remains closed. If the flue gas temperature T i continues to drop, for example when the flue gas temperature T i has reached the value which is just permissible for trouble-free flue gas cleaning during part-load operation, the valve 15c is opened and also the valve 15b is closed.
  • the sections 20 and 21 of the heating surface 5 are then switched off and thus separated from the water-steam cycle.
  • the feed water S remains in the pipes 35 of the sections 20 and 21 which are not flowed through. Since the boiling temperature of the water is always higher than the flue gas temperature in this area of the waste heat boiler 4 under the prevailing pressure conditions, the sections 20, 21 of the heating surface 5 which are not flowed through cannot evaporate.
  • the heating surface 5 which is effectively used for heat transfer is increasingly increased.
  • the sections 20 and 21 of the heating surface 5, depending on the flue gas temperature T i at the outlet of the steam generator 1, are switched on one after the other in the water-steam cycle by reversing the valves 15a, 15b, 15c.
  • the regulation takes place via the controller 14, which emits corresponding control signals to the valves 15a, 15b, 15c.
  • the control signals are derived from a comparison value, which is formed from a deviation of the measured flue gas temperature T i (actual value) from a target value T s .
  • the device for temperature control accordingly comprises only short connecting lines on the feed water side between the feed water line 30 and at least two or more valves 15a, 15b, 15c.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
  • Chimneys And Flues (AREA)
  • Devices For Medical Bathing And Washing (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)

Abstract

A process and device are disclosed for regulating the flue gas temperature (T) at the outlet of a steam generator (1) with a heating surface (5) for transmitting heat from the flue gas (R) to the supply water (S). In order to prevent the flue gas temperature from falling below a set value (Ts) when it enters a cleaning installation (7), the heating surface (5) used by the flowing supply water (S) is modified when the flue gas temperature (Ti) changes.

Description

Die Erfindung bezieht sich auf ein Verfahren und eine Vorrichtung zur Einstellung der Rauchgastemperatur am Austritt eines in einer Schwel-Brenn-Anlage eingesetzten Dampferzeugers, der eine zur Wärmeübertragung zwischen dem Rauchgas und dem Speisewasser nutzbare Heizfläche aufweist, und dem rauchgasseitig eine Reinigungsanlage nachgeschaltet ist.The invention relates to a method and a device for adjusting the flue gas temperature at the outlet of a steam generator used in a smoldering furnace, which has a heating surface that can be used for heat transfer between the flue gas and the feed water, and which is followed by a cleaning system on the flue gas side.

In einem derartigen Dampferzeuger wird durch indirekten Wärmetausch zwischen heißem Rauchgas und Speisewasser, das in einem wasser-Dampf-Kreislauf geführt wird, Dampf z.B. für eine Dampfturbine erzeugt. Das Rauchgas wird durch Verbrennung eines fossilen Brennstoffs in einer Brennkammer der Schwel-Brenn-Anlage (EP-PS 0 340 537) erzeugt. Das Speisewasser strömt innerhalb des Dampferzeugers entlang einer üblicherweise in Form von Rohren oder Rohrbündeln ausgebildeten Heizfläche und nimmt dabei Wärme vom Rauchgas auf. Das abgekühlte Rauchgas wird bei Austritt aus dem Dampferzeuger zunächst gereinigt und anschließend über einen Kamin an die Umgebung abgegeben.In such a steam generator, steam is converted, e.g. by indirect heat exchange between hot flue gas and feed water, which is conducted in a water-steam cycle. generated for a steam turbine. The flue gas is generated by burning a fossil fuel in a combustion chamber of the smoldering furnace (EP-PS 0 340 537). The feed water flows inside the steam generator along a heating surface usually in the form of tubes or tube bundles and absorbs heat from the flue gas. The cooled flue gas is first cleaned when it leaves the steam generator and then released into the environment via a chimney.

Bei einer nassen Rauchgasreinigung wird die mit den Reaktionsprodukten versetzte Waschflüssigkeit mittels des den Dampferzeuger verlassenden Rauchgases verdampft, wobei die getrockneten Reaktionsprodukte abgeschieden werden. Um störende Ablagerungen in der Reinigungsanlage zu vermeiden, darf die Rauchgastemperatur am Eintritt in die Reinigungsanlage einen vorgegebenen Wert nicht unterschreiten. Dabei stehen zwei Tatsachen bezüglich der Rauchgastemperatur am Austritt des Dampferzeugers konträr gegenüber: während der Wirkungsgrad des Dampferzeugers mit Abnahme der Rauchgastemperatur zunimmt, erhöht sich gleichzeitig die Gefahr einer Betriebsstörung der Reinigungsanlage. Deshalb wird üblicherweise die Rauchgastemperatur am Austritt des Dampferzeugers bei Vollastbetrieb möglichst niedrig über der minimal zulässigen Rauchgastemperatur für die Reinigungsanlage gehalten. Bei Teillastbetrieb sinkt allerdings die Rauchgastemperatur ab, so daß ohne spezielle Maßnahmen die Gefahr einer Betriebsstörung in der Reinigungsanlage besteht. Es ist daher erforderlich, insbesondere bei Teillastbetrieb, die Rauchgastemperatur am Austritt des Dampferzeugers einzustellen oder zu regeln.In the case of wet flue gas cleaning, the scrubbing liquid mixed with the reaction products is evaporated by means of the flue gas leaving the steam generator, the dried reaction products being separated off. In order to avoid disturbing deposits in the cleaning system, the flue gas temperature at the entrance to the cleaning system must not fall below a predetermined value. There are two contrasting facts regarding the flue gas temperature at the outlet of the steam generator: while the efficiency of the steam generator increases as the flue gas temperature decreases, the risk of malfunctioning of the cleaning system increases at the same time. Therefore, the flue gas temperature at the outlet of the steam generator is usually as low as possible at full load the minimum permissible flue gas temperature for the cleaning system. During part-load operation, however, the flue gas temperature drops, so that there is a risk of malfunction in the cleaning system without special measures. It is therefore necessary to adjust or regulate the flue gas temperature at the outlet of the steam generator, particularly in the case of partial load operation.

Dazu wird bei einem bekannten Verfahren der Brennstoff mit erhöhtem Luftüberschuß verbrannt, so daß die Wärmeübertragung in den Konvektionszug des Dampferzeugers verlagert wird und die Rauchgastemperatur am Austritt des Dampferzeugers steigt. Nachteilig ist dabei der Verlust an nutzbarer Wärme aufgrund des erhöhten Volumenstroms des Rauchgases.For this purpose, in a known method, the fuel is burned with an increased excess of air, so that the heat transfer is shifted into the convection train of the steam generator and the flue gas temperature rises at the outlet of the steam generator. The disadvantage here is the loss of usable heat due to the increased volume flow of the flue gas.

Bei einem anderen Verfahren wird ein Teil des heißen Rauchgases unter Umgehung der Heizfläche am Austritt des Dampferzeugers dem abgekühlten Rauchgas zugemischt, so daß eine vorgegebene Rauchgastemperatur eingehalten werden kann. Nachteilig ist dabei die Bereitstellung eines voluminösen Rauchgas-Bypasses. Außerdem ist eine Temperaturregelung aufgrund von bei der Mischung sich bildenden Strähnen äußerst schwierig.In another method, a part of the hot flue gas is mixed with the cooled flue gas bypassing the heating surface at the outlet of the steam generator, so that a predetermined flue gas temperature can be maintained. The disadvantage here is the provision of a voluminous flue gas bypass. In addition, temperature control is extremely difficult due to strands forming during the mixing.

Bei einem häufig angewendeten Verfahren wird, insbesondere bei Teillastbetrieb, das Speisewasser vor Eintritt in den Dampferzeuger durch indirekten Wärmetausch mit Dampf, der dem Wasser-Dampf-Kreislauf der Dampfturbine entnommen ist, vorgewärmt. Dies führt allerdings dazu, daß der Ge-samtwirkungsgrad nur begrenzt ist.In a method which is frequently used, in particular in the case of part-load operation, the feed water is preheated before it enters the steam generator by indirect heat exchange with steam, which is taken from the water-steam circuit of the steam turbine. However, this means that the overall efficiency is only limited.

Der Erfindung liegt daher die Aufgabe zugrunde, ein besonders einfaches Verfahren zur Einstellung der Rauchgastemperatur anzugeben. Insbesondere soll sich das Verfahren eignen zur Regelung, bei der eine Absenkung der Rauchgastemperatur am Austritt des Dampferzeugers, der gleichzeitig Eintritt einer Reinigungsanlage ist, unter einen Minimalwert sicher vermieden ist. Weiter soll eine möglichst einfache Vorrichtung angegeben werden, mit der ein hoher Gesamtwirkungsgrad erreichbar ist.The invention is therefore based on the object of specifying a particularly simple method for setting the flue gas temperature. In particular, the method is intended to be suitable for control in which a reduction in the flue gas temperature at the outlet of the steam generator takes place simultaneously Entry of a cleaning system is safely avoided below a minimum value. Furthermore, the simplest possible device is to be specified with which a high overall efficiency can be achieved.

Bezüglich des Verfahrens wird diese Aufgabe erfindungsgemäß dadurch gelöst, daß die zur Wärmeübertragung jeweils wirksam genutzte Heizfläche in Abhängigkeit von der Rauchgastemperatür verändert wird, wobei bei einer Abweichung der Rauchgastemperatur von einem oberhalb der minimal zulässigen Rauchgastemperatur für die Rauchgasreinigung liegenden Sollwert in Strömungsrichtung des Speisewassers hintereinander angeordnete Abschnitte der Heizfläche zu- oder abgeschaltet werden.With regard to the method, this object is achieved according to the invention in that the heating surface which is effectively used for heat transfer is changed as a function of the flue gas temperature, with the flue gas temperature deviating from a setpoint above the minimum permissible flue gas temperature for flue gas cleaning, arranged in succession in the flow direction of the feed water Sections of the heating surface can be switched on or off.

Dabei wird zweckmäßigerweise bei Absinken der Rauchgastemperatur, insbesondere bei Teillastbetrieb, bei in Gegenrichtung zur Rauchgasströmung strömendem Speisewasser zunächst der dem Austritt des Dampferzeugers nächstliegende Abschnitt der Heizfläche abgeschaltet. Mit zunehmender Absenkung der Rauchgastemperatur werden in Gegenrichtung zur Strömungsrichtung des Rauchgases weitere Abschnitte nacheinander abgeschaltet. Diese können bei wieder ansteigender Rauchgastemperatur in umgekehrter Reihenfolge nacheinander zugeschaltet werden.In this case, when the flue gas temperature drops, in particular during part-load operation, with feed water flowing in the opposite direction to the flue gas flow, the section of the heating surface closest to the outlet of the steam generator is first switched off. With increasing decrease in the flue gas temperature, further sections are switched off in the opposite direction to the flow direction of the flue gas. When the flue gas temperature rises again, these can be switched on in reverse order.

Bezüglich der Vorrichtung wird die Aufgabe erfindungsgemäß dadurch gelöst, daß die vom strömenden Speisewasser genutzte Heizfläche in Abhängigkeit von der Rauchgastemperatur steuerbar ist, wobei die Heizfläche eine Anzahl von einzeln zu- oder abschaltbaren Abschnitten umfaßt, die in Strömungsrichtung des Rauchgases hintereinander angeordnet und vom Speisewasser in Gegenrichtung nacheinander durchströmbar sind.With regard to the device, the object is achieved in that the heating surface used by the flowing feed water can be controlled as a function of the flue gas temperature, the heating surface comprising a number of sections which can be switched on or off individually, which are arranged one behind the other in the flow direction of the flue gas and from the feed water in Flow in the opposite direction one after the other.

Dabei kann jeder Abschnitt eingangsseitig mit einem Stellglied verbunden sein. Außerdem kann jeder Abschnitt zweckmäßigerweise am Eintritt einen Eintrittssammler zum Sammeln von Speisewasser aufweisen.Each section can be connected on the input side to an actuator. In addition, each section can be conveniently located at the entrance have an inlet collector for collecting feed water.

Die Vorrichtung umfaßt vorteilhafterweise einen ausgangsseitig mit mindestens einem Stellglied verbundenen Regler, dessen Eingangsgröße der Ist-Wert der Rauchgastemperatur ist.The device advantageously comprises a controller connected on the output side to at least one actuator, the input variable of which is the actual value of the flue gas temperature.

Ausführungsbeispiele der Erfindung werden anhand einer Zeichnung näher erläutert; darin zeigen:

  • Figur 1 schematisch einen Dampferzeuger mit vorgeschalteter Brennkammer und nachgeschalteter Reinigunganlage und
  • Figur 2 einen Ausschnitt II aus Figur 1 in größerem Maßstab mit einzeln zu- oder abschaltbaren Abschnitten einer Heizfläche.
Embodiments of the invention are explained in more detail with reference to a drawing; show in it:
  • Figure 1 shows schematically a steam generator with an upstream combustion chamber and downstream cleaning system and
  • Figure 2 shows a section II of Figure 1 on a larger scale with sections of a heating surface that can be switched on or off individually.

Einander entsprechende Teile sind in beiden Figuren mit den gleichen Bezugszeichen versehen.Corresponding parts are provided with the same reference symbols in both figures.

Der in Figur 1 dargestellte Dampferzeuger 1 ist z.B. Teil einer nicht näher gezeigten Schwel-Brenn-Anlage. Er umfaßt eine Brennkammer 2, der über einen Rauchgaszug 3 ein Abhitzekessel 4 nachgeschaltet ist. Innerhalb des Abhitzekessels 4 sind Heizflächen 5 in Form von Rohren oder Rohrbündeln, z.B. hängend, angeordnet.The steam generator 1 shown in Figure 1 is e.g. Part of a smoldering and burning plant, not shown in detail. It comprises a combustion chamber 2, which is followed by a waste heat boiler 4 via a flue gas duct 3. Inside the waste heat boiler 4 there are heating surfaces 5 in the form of tubes or tube bundles, e.g. hanging, arranged.

Der Dampferzeuger 1 ist ausgangsseitig über eine Rauchgasleitung 6 an eine Reinigungsanlage 7 angeschlossen. Die Reinigungsanlage 7 umfaßt einen Sprühtrockner 8, dem ein Abscheider 9, z.B. ein Elektro-Filter, und ein Naßreiniger 10 nachgeschaltet sind. Der Naßreiniger 10 ist über eine Leitung 11 mit dem Sprühtrockner 8 verbunden. Die Rauchgasleitung 6 mündet hinter der Reinigungsanlage 7 in einen Kamin 12.The steam generator 1 is connected on the output side to a cleaning system 7 via a flue gas line 6. The cleaning system 7 comprises a spray dryer 8, which is followed by a separator 9, for example an electric filter, and a wet cleaner 10. The wet cleaner 10 is connected to the spray dryer 8 via a line 11. The flue gas line 6 opens into a chimney 12 behind the cleaning system 7.

Am Austritt des Dampferzeugers 1 ist ein Temperatursensor 13 vorgesehen, der mit einem Regler 14 verbunden ist. Der Regler 14 ist ausgangsseitig mit einer Anzahl von als Ganzes mit 15 bezeichneten Stellgliedern in Form von Ventilen 15a, 15b, 15c (Figur 2) verbunden. Wie später näher erläutert, wird mittels der Stellglieder 15 die Verteilung des über eine Leitung 30 in den Dampferzeuger 1 eintretenden Speisewassers S auf eine Economizer-Heizfläche, die zur Vorwärmung des Speisewassers S dient, beeinflußt.At the outlet of the steam generator 1, a temperature sensor 13 is provided, which is connected to a controller 14. The controller 14 is connected on the output side to a number of actuators, designated as a whole by 15, in the form of valves 15a, 15b, 15c (FIG. 2). As explained in more detail later, the actuators 15 influence the distribution of the feed water S entering the steam generator 1 via a line 30 to an economizer heating surface which serves to preheat the feed water S.

Beim Betrieb des Dampferzeugers 1 wird in der Brennkammer 2 erzeugtes Rauchgas R entlang der dargestellten Pfeile durch den Dampferzeuger 1 geführt. Dabei wird Wärme von dem heißen Rauchgas R über die Heizflächen 5 auf das in einem nicht näher dargestellten Wasser-Dampf-Kreislauf einer Dampfturbine strömende Speisewasser S übertragen. Das den Dampferzeuger 1 verlassende abgekühlte Rauchgas R wird in der Reinigungsanlage 7 gereinigt. Die Rauchgastemperatur Ti am Austritt des Dampferzeugers 1 beträgt bei Vollastbetrieb noch etwa 220° C.When the steam generator 1 is operating, the flue gas R generated in the combustion chamber 2 is guided through the steam generator 1 along the arrows shown. In this case, heat is transferred from the hot flue gas R via the heating surfaces 5 to the feed water S flowing in a water-steam cycle (not shown) of a steam turbine. The cooled flue gas R leaving the steam generator 1 is cleaned in the cleaning system 7. The flue gas temperature T i at the outlet of the steam generator 1 is still approximately 220 ° C. at full load.

Die Reinigung erfolgt innerhalb des Naßreinigers 10 mittels einer Waschflüssigkeit, die alkalische Bestandteile, z.B. Natriumhydroxid, enthält. Die alkalischen Bestandteile bilden mit in dem Rauchgas R enthaltenen sauren, z.B. chlorhaltigen Stoffen als Reaktionsprodukte im wesentlichen Salze. Die Waschflüssigkeit wird zusammen mit den Reaktionsprodukten über die Leitung 11 dem Sprühtrockner 8 zugeführt. Dort wird die Waschflüssigkeit durch Kontakt mit dem Rauchgas R verdampft. Die gleichzeitig mit der Verdampfung getrockneten Reaktionsprodukte, d.h. im wesentlichen die Salze, werden in dem Filter 9 abgeschieden. Das Rauchgas R wird in der Reinigungsanlage 7 auf eine Temperatur von etwa 70° C abgekühlt.The cleaning takes place within the wet cleaner 10 by means of a washing liquid which contains alkaline components, for example sodium hydroxide. The alkaline constituents essentially form salts with the acidic, for example chlorine-containing substances contained in the flue gas R as reaction products. The washing liquid is fed to the spray dryer 8 together with the reaction products via line 11. There the washing liquid is evaporated by contact with the flue gas R. The reaction products dried at the same time as the evaporation, ie essentially the salts, are separated in the filter 9. The flue gas R is cooled in the cleaning system 7 to a temperature of about 70 ° C.

Wie Figur 2 zeigt, ist jede zur Vorwärmung des Speisewassers S dienende Economizer-Heizfläche 5 in eine Anzahl von hintereinander liegenden Abschnitten, vorzugsweise in drei Abschnitte 20 bis 22, unterteilt. Jeder der Abschnitte 20, 21 und 22 ist sowohl eingangsseitig als auch ausgangsseitig mit einem Sammler 23, 24, 25 bzw. 26 verbunden. Außerdem ist jeder der Abschnitte 20 bis 22 über die Eintrittssammler 23, 24, 25 mit einem der Ventile 15a, 15b bzw. 15c verbunden. Die Ventile 15a, 15b, 15c sind an eine gemeinsame Speisewasserleitung 30 angeschlossen. Der Sammler 26 ist über eine Leitung 31 in nicht näher dargestellter Art und Weise mit den weiteren Heizflächen 5 des Dampferzeugers 1 verbunden.As FIG. 2 shows, each economizer heating surface 5 used to preheat the feed water S is divided into a number of sections lying one behind the other, preferably into three sections 20 to 22. Each of the sections 20, 21 and 22 is connected to a collector 23, 24, 25 and 26 both on the input side and on the output side. In addition, each of the sections 20 to 22 is connected to one of the valves 15a, 15b and 15c via the inlet manifolds 23, 24, 25. The valves 15a, 15b, 15c are connected to a common feed water line 30. The collector 26 is connected via a line 31 in a manner not shown to the other heating surfaces 5 of the steam generator 1.

Das Speisewasser S wird im Gegenstrom zur Strömungsrichtung des Rauchgases R durch mäanderförmig angeordnete Rohrbündel 35 geführt, deren Wände die Heizfläche 5 bilden. Dabei wird das Rauchgas R abgekühlt, wobei zunächst das Ventil 15a geöffnet ist und die Ventile 15b und 15c geschlossen sind. Bei Absinken der Rauchgastemperatur Ti am Austritt des Dampferzeugers 1 wird die zur Wärmeübertragung wirksam genutzte Heizfläche 5 verringert. Dazu wird zunächst das Ventil 15b geöffnet und das Ventil 15a geschlossen. Das Ventil 15c bleibt dann weiterhin geschlossen. Sinkt die Rauchgastemperatur Ti weiter ab, z.B. wenn bei Teillastbetrieb die Rauchgastemperatur Ti den für eine störungsfreie Rauchgasreinigung gerade noch zulässigen Wert erreicht hat, so wird das Ventil 15c geöffnet und auch das Ventil 15b geschlossen. Die Abschnitte 20 und 21 der Heizfläche 5 sind dann abgeschaltet und somit vom Wasser-Dampf-Kreislauf getrennt. In den jeweils nicht durchströmten Rohren 35 der Abschnitte 20 und 21 bleibt das Speisewasser S stehen. Da bei den herrschenden Druckverhältnissen die Siedetemperatur des Wassers stets höher ist als die Rauchgastemperatur in diesem Bereich des Abhitzekessels 4, können die jeweils nicht durchströmten Abschnitte 20, 21 der Heizfläche 5 nicht ausdampfen.The feed water S is conducted in counterflow to the direction of flow of the flue gas R through meandering tube bundles 35, the walls of which form the heating surface 5. In the process, the flue gas R is cooled, the valve 15a first being open and the valves 15b and 15c being closed. When the flue gas temperature T i drops at the outlet of the steam generator 1, the heating surface 5 effectively used for heat transfer is reduced. For this purpose, valve 15b is first opened and valve 15a is closed. The valve 15c then remains closed. If the flue gas temperature T i continues to drop, for example when the flue gas temperature T i has reached the value which is just permissible for trouble-free flue gas cleaning during part-load operation, the valve 15c is opened and also the valve 15b is closed. The sections 20 and 21 of the heating surface 5 are then switched off and thus separated from the water-steam cycle. The feed water S remains in the pipes 35 of the sections 20 and 21 which are not flowed through. Since the boiling temperature of the water is always higher than the flue gas temperature in this area of the waste heat boiler 4 under the prevailing pressure conditions, the sections 20, 21 of the heating surface 5 which are not flowed through cannot evaporate.

Steigt die Rauchgastemperatur Ti am Austritt des Dampferzeugers 1 wieder an, z.B. bei erneutem Vollastbetrieb, so wird die zur Wärmeübertragung wirksam genutzte Heizfläche 5 zunehmend vergrößert. Dazu werden die Abschnitte 20 und 21 der Heizfläche 5 in Abhängigkeit von der Rauchgastemperatur Ti am Austritt des Dampferzeugers 1 durch entsprechende Umschaltung der Ventile 15a, 15b, 15c in umgekehrter Reihenfolge nacheinander in den Wasser-Dampf-Kreislauf wieder eingeschaltet. Die Regelung erfolgt über den Regler 14, der entsprechende Steuersignale an die Ventile 15a, 15b, 15c abgibt. Die Steuersignale sind von einem Vergleichswert abgeleitet, der aus einer Abweichung der gemessenen Rauchgastemperatur Ti (Ist-Wert) von einem Soll-Wert Ts gebildet wird.If the flue gas temperature T i rises again at the outlet of the steam generator 1, for example during renewed full-load operation, the heating surface 5 which is effectively used for heat transfer is increasingly increased. For this purpose, the sections 20 and 21 of the heating surface 5, depending on the flue gas temperature T i at the outlet of the steam generator 1, are switched on one after the other in the water-steam cycle by reversing the valves 15a, 15b, 15c. The regulation takes place via the controller 14, which emits corresponding control signals to the valves 15a, 15b, 15c. The control signals are derived from a comparison value, which is formed from a deviation of the measured flue gas temperature T i (actual value) from a target value T s .

Bei einem üblicherweise eingesetzten Dampferzeuger 1 sind bereits sogenannte Entlüftungssammler vorhanden, die bei einer Nachrüstung in einfacher Weise zu Eintrittssammlern 23 bis 25 umgebildet werden können. Die Vorrichtung zur Temperaturregelung umfaßt demnach auf der Speisewasserseite nur kurze Verbindungsleitungen zwischen der Speisewasserleitung 30 und mindestens zwei oder mehreren Ventilen 15a, 15b, 15c.In a steam generator 1 that is usually used, so-called ventilation collectors are already present, which can be converted into inlet collectors 23 to 25 in a simple manner when retrofitted. The device for temperature control accordingly comprises only short connecting lines on the feed water side between the feed water line 30 and at least two or more valves 15a, 15b, 15c.

Claims (6)

  1. Method for controlling the flue gas temperature at the outlet of a steam generator having a heating surface (5) for heat transfer between the flue gas (R) and the supply water (S), wherein the cooled flue gas (R) is cleaned upon emerging from the steam generator, characterised in that the heating surface (5), which is used effectively in each case for the heat transfer, is altered as a function of the flue gas temperature (Ti), wherein in the event of the flue gas temperature (Ti) deviating from a desired value (Ts) above the minimum acceptable flue gas temperature for the cleaning of the flue gas, sections (20, 21, 22) of the heating surface (5), which sections are arranged one after the other in the flow direction of the supply water (S), are switched on or off.
  2. Method according to claim 1, characterised in that in the event of the flue gas temperature (Ti) falling when supply water (S) is flowing in the opposite direction to the flow of flue gas, the section (20) of the heating surface (5) that is adjacent to the outlet of the steam generator (1) is switched off first of all.
  3. Device for adjusting the flue gas temperature at the outlet of a steam generator, subsequently connected to the flue-gas side of which is a flue gas cleaning unit (7), with the steam generator having a heating surface (5) which can be used for heat transfer between the flue gas (R) and the supply water (S), characterised in that the heating surface, which is used by the flowing supply water (S), can be controlled as a function of the flue gas temperature (Ti), with the heating surface (5) being divided into a number of sections (20, 21, 22), each of which sections (20, 21, 22) can be switched on or off individually.
  4. Device according to claim 3, characterised in that the sections (20, 21, 22) are arranged one after the other in the flow direction of the flue gas (R), and supply water (S) flows through said sections one after the other in the opposite direction, with each section (20, 21, 22) being connected on the input side to a final control element (15a, 15b, 15c).
  5. Device according to claim 4, characterised in that at the inlet each section (20, 21, 22) has an inlet collector (23, 24 and 25 respectively) for collecting supply water (S).
  6. Device according to claim 4 or 5, characterised by a controller (14), which is connected on the output side to at least one final control element (15) and the input quantity of which is the actual value of the flue gas temperature (Ti).
EP93907804A 1992-06-01 1993-04-19 Process and device for regulating the flue gas temperature at the outlet of a steam generator Expired - Lifetime EP0643816B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4218016 1992-06-01
DE4218016A DE4218016A1 (en) 1992-06-01 1992-06-01 Method and device for controlling the flue gas temperature at the outlet of a steam generator
PCT/DE1993/000340 WO1993024790A1 (en) 1992-06-01 1993-04-19 Process and device for regulating the flue gas temperature at the outlet of a steam generator

Publications (3)

Publication Number Publication Date
EP0643816A1 EP0643816A1 (en) 1995-03-22
EP0643816B1 true EP0643816B1 (en) 1996-10-16
EP0643816B2 EP0643816B2 (en) 2003-10-29

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ID=6460138

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Application Number Title Priority Date Filing Date
EP93907804A Expired - Lifetime EP0643816B2 (en) 1992-06-01 1993-04-19 Process and device for regulating the flue gas temperature at the outlet of a steam generator

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EP (1) EP0643816B2 (en)
JP (1) JPH07503530A (en)
CN (1) CN1044403C (en)
DE (2) DE4218016A1 (en)
ES (1) ES2094536T5 (en)
WO (1) WO1993024790A1 (en)

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US9297278B2 (en) 2011-05-27 2016-03-29 General Electric Company Variable feedwater heater cycle

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DK0745807T3 (en) * 1995-05-31 2000-02-21 Asea Brown Boveri steam Generator
FI970438A0 (en) 1996-12-19 1997-02-03 Kvaerner Pulping Oy Foerfarande i panna, saerskilt i sodapanna
DE10004187C5 (en) * 2000-02-01 2013-06-06 Siemens Aktiengesellschaft Method for operating a gas and steam turbine plant and thereafter operating plant
JP5995685B2 (en) * 2012-11-27 2016-09-21 クボタ環境サ−ビス株式会社 Waste heat recovery equipment
DE102013211376B4 (en) * 2013-06-18 2015-07-16 Siemens Aktiengesellschaft Method and device for controlling the injection of water into the flue gas duct of a gas and steam turbine plant

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US3040719A (en) * 1952-04-21 1962-06-26 Bailey Meter Co Vapor generating and superheating systems
US3807364A (en) * 1972-07-20 1974-04-30 Westinghouse Electric Corp Mixing header
JPS5836243B2 (en) * 1979-12-15 1983-08-08 工業技術院長 steam generator
DE3344712C1 (en) * 1983-12-10 1985-04-18 Balcke-Dürr AG, 4030 Ratingen Steam generator
DK154731C (en) * 1985-05-21 1989-05-08 Burmeister & Wains Energi Steam boiler with catalytic flue gas treatment as well as boiler operation
JP2592061B2 (en) * 1986-06-02 1997-03-19 バブコツク日立株式会社 Waste heat recovery boiler
US4799461A (en) * 1987-03-05 1989-01-24 Babcock Hitachi Kabushiki Kaisha Waste heat recovery boiler

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Publication number Priority date Publication date Assignee Title
US9297278B2 (en) 2011-05-27 2016-03-29 General Electric Company Variable feedwater heater cycle

Also Published As

Publication number Publication date
ES2094536T5 (en) 2004-07-01
WO1993024790A1 (en) 1993-12-09
EP0643816B2 (en) 2003-10-29
EP0643816A1 (en) 1995-03-22
JPH07503530A (en) 1995-04-13
CN1044403C (en) 1999-07-28
ES2094536T3 (en) 1997-01-16
CN1080040A (en) 1993-12-29
DE59304208D1 (en) 1996-11-21
DE4218016A1 (en) 1993-12-02

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