EP0410111B1 - Heat recovery boiler for a gas and steam turbine plant - Google Patents

Heat recovery boiler for a gas and steam turbine plant Download PDF

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Publication number
EP0410111B1
EP0410111B1 EP19900110081 EP90110081A EP0410111B1 EP 0410111 B1 EP0410111 B1 EP 0410111B1 EP 19900110081 EP19900110081 EP 19900110081 EP 90110081 A EP90110081 A EP 90110081A EP 0410111 B1 EP0410111 B1 EP 0410111B1
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Prior art keywords
heating surfaces
pressure
steam
low
water
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EP19900110081
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German (de)
French (fr)
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EP0410111A1 (en
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Hermann Brückner
Lothar Stadie
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Siemens AG
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Siemens AG
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
    • F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
    • F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
    • F01K23/10—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle with exhaust fluid of one cycle heating the fluid in another cycle
    • F01K23/106—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle with exhaust fluid of one cycle heating the fluid in another cycle with water evaporated or preheated at different pressures in exhaust boiler

Definitions

  • the invention relates to a heat recovery steam generator for a gas and steam turbine power plant with high-pressure superheater heating surfaces, reheater heating surfaces, high-pressure evaporator heating surfaces, low-pressure superheater heating surfaces, low-pressure evaporator heating surfaces and economiser heating surfaces.
  • Gas and steam turbine power plants usually contain a heat recovery steam generator installed in the exhaust pipe behind the gas turbine.
  • heat recovery steam generators the sensible heat of the exhaust gases leaving the gas turbine is used to generate steam.
  • a steam turbine power plant is operated with the generated steam.
  • the hot exhaust gases from the gas turbine give off their heat to the various heating surfaces installed in the heat recovery steam generator.
  • these heating surfaces are often subdivided into feed water preheater heating surfaces, economiser heating surfaces, low-pressure evaporator heating surfaces, low-pressure superheater heating surfaces, high-pressure evaporator heating surfaces, intermediate superheater heating surfaces and high-pressure superheater heating surfaces required operating temperature more towards the hotter or more towards the cooler end of the heat recovery steam generator.
  • water-steam separation vessels usually in the form of steam drums or so-called bottles
  • water-steam mixture flowing out of the evaporator heating surfaces is separated into water and steam in these.
  • the steam reaches the downstream superheater heating surfaces from the upper end of the respective water-steam separation vessel.
  • the water is drawn off from the lower end of the respective water-steam separating vessel by means of a circulating pump and again conveyed back into the respective evaporator heating surfaces.
  • the economiser outlet temperature has previously been set to a very low design value and the economiser heating surfaces have been installed near the cool end of the heat recovery steam generator, i.e. behind the low-pressure evaporator heating surfaces in the direction of flow of the gas turbine exhaust gases .
  • the resulting reduction in the maximum amount of live steam that could be generated was accepted.
  • the invention is therefore based on the object of showing a way in which the economiser heating surfaces can be regulated to an optimal operating temperature in the nominal load operation and how evaporation of the economiser heating surfaces can nevertheless be avoided in part-load operation.
  • the economiser heating surfaces are arranged according to the invention in the flow direction of the gas turbine exhaust gases in front of the low-pressure evaporator heating surfaces and on the output side both on the high-pressure evaporator heating surfaces and via a compensating line with a reducing valve to a medium-pressure water-steam separating vessel upstream of the reheater heating surfaces are connected, it is achieved that the economizer's outlet temperature is raised to a level at nominal load which enables the subsequent evaporator heating surfaces to generate more steam.
  • the economiser heating surfaces and the low-pressure superheater heating surfaces can be installed in the same temperature range of the heat recovery steam generator. This measure raises the outlet temperature of the feed water at the outlet of the economiser heating surfaces to a value which later enables the high-pressure evaporator heating surfaces to produce steam in maximum quantities.
  • the medium-pressure water-steam separation vessel can be connected on the water side via an outlet line with a reducing valve to a low-pressure water-steam separation vessel upstream of the low-pressure superheater heating surfaces.
  • This measure ensures that excess water can be drained into the low-pressure water-steam separating vessel in the medium-pressure system by opening the reducing valve in the drain line and in turn ensures increased steam generation there.
  • the figure is a schematic representation of the arrangement and circuit of the individual heating surfaces in the heat recovery steam generator of a gas and steam turbine power plant.
  • the schematic representation of the figure shows the structure of the gas and steam turbine power plant 1 according to the invention consisting of a gas turbine power plant part 2 and a steam turbine power plant part 4.
  • the gas turbine power plant part 2 comprises a gas turbine 6, an air compressor driven by the gas turbine 8 and generator 10 and a combustion chamber 12 arranged between the air compressor and the gas turbine with a separate fuel feed 14 and an exhaust gas line 16 for the exhaust gases of the gas turbine 6.
  • This exhaust gas line 16 is connected to the waste heat steam generator 18 of the steam turbine power plant part 4.
  • the steam turbine power plant part 4 comprises the heat recovery steam generator 18, a three-casing steam turbine 20 connected on the steam side to the heat recovery steam generator with a high-pressure part 22, a medium-pressure part 24 and a low-pressure part 26 and a generator 30 seated on the same shaft 28.
  • the steam turbine 20 On the low-pressure part 26, the steam turbine 20 has a capacitor connected, which is connected via a condensate line 34 and a condensate pump 36 to a feed water tank 38.
  • the following heating surfaces are arranged one after the other from the hot to the cold side: at the hot end, reheater heating surfaces 40 and high-pressure superheater heating surfaces 42 are arranged at the same temperature level, followed by high-pressure evaporator heating surfaces 44 and these in turn economizer heating surfaces 46 and low-pressure superheaters -Heating surfaces 48, both of which are also arranged at the same temperature level. These in turn are followed by low-pressure evaporator heating surfaces 50 and these, in turn, feed water preheating heating surfaces 52.
  • the high-pressure and low-pressure evaporator heating surfaces are connected on the inlet and outlet sides to a water / steam separating vessel - in the exemplary embodiment a steam drum 54, 56 each.
  • a circulation pump 58, 60 ensures that the feed water is conveyed from the respective steam drum into the associated evaporator heating surface and back into the same steam drum.
  • the feed water tank 38 is connected to the feed water preheating heating surfaces 52 via a feed water circulation pump 62 with a downstream control valve 63, these feed water preheating heating surfaces on the output side, in turn, into the feed water tank 38 via a further control valve 65.
  • the feed water tank 38 is connected to the economizer heating surfaces 46 via a feed water line 66 equipped with a feed water pump 64 with a downstream control valve 67. On the output side, these are connected to the water-steam separation vessel 54 of the high-pressure evaporator heating surfaces 44 via a control valve 68.
  • the economizer heating surfaces 46 are connected on the output side via an adjustable reducing valve 70 to a further water-steam separating vessel 72, which is connected upstream of the reheater heating surfaces 40 on the steam side, and on the water side via a further adjustable reducing valve 74 to a second water-steam separating vessel 76 is connected.
  • the latter is connected on the steam side to the input of the low-pressure superheater heating surfaces 48.
  • the water-steam separation vessel 76 is connected to the feed water tank 38 via a further adjustable reducing valve 78.
  • the feed water preheating heating surfaces 52 are also connected on the output side via a control valve 80 to the water-steam separating vessel of the low-pressure evaporator heating surfaces 50 which is designed as a steam drum 56.
  • This steam drum 56 of the low-pressure evaporator heating surfaces 50 is connected to the low-pressure superheater heating surfaces 48 on the steam side, and these in turn are connected on the output side to the low-pressure part 26 of the steam turbine 20.
  • the water-steam separating vessel of the high-pressure evaporator heating surfaces 44 which is designed as a steam drum 54, is connected on the steam side to the high-pressure superheater heating surfaces 42 and this in turn is connected on the outlet side to the high-pressure part 22 of the steam turbine 20.
  • the high-pressure part 22 of the steam turbine 20 is connected on the output side at A to the input of the reheater heating surfaces 40, and these in turn are connected on the output side to the input of the medium-pressure part 24 of the steam turbine.
  • the medium-pressure part of the steam turbine like the low-pressure superheater heating surfaces 48, is connected to the inlet of the low-pressure part 26 of the steam turbine.
  • the feed water in the feed water tank 38 is pumped by the feed water circulation pump 62 into the feed water preheating heating surfaces 52, where it is heated, and from there back into the feed water tank.
  • feed water is also pressed into the economizer heating surfaces 46, heated there and further conveyed via the feed water line 66 and the control valve 68 into the water-steam separating vessel of the high-pressure evaporator heating surfaces 44 designed as a high-pressure drum 54.
  • a circulation pump 58 is connected to this high-pressure drum 54, which pumps the feed water into the high-pressure evaporator heating surfaces 44 and back into the high-pressure drum 54.
  • the feed water heats up so strongly that part of the feed water reaches the high pressure drum 54 as steam, is separated there from the rest of the feed water and flows via the high pressure steam line 82 into the high pressure superheater heating surfaces 42 and from there into the high pressure part 22 of the steam turbine.
  • the exhaust steam from the high-pressure steam turbine 22 flows at A into the reheater heating surfaces 40 at the hot end of the waste heat steam generator 18, and is in these
  • the reheater heating surfaces are heated to approximately the same temperature as the high-pressure steam in the high-pressure superheater heating surfaces 42 and are thus dried as medium-pressure steam at the inlet of the medium-pressure part 24 of the steam turbine 20 and from the medium-pressure part of the steam turbine into the low-pressure part 26 of the steam turbine and from there again in the Condenser 32.
  • the condensate from the condenser is conveyed into the feed water tank 38 via the condensate pump 36.
  • the flow through the feed water preheating heating surfaces 52 can now be increased in the waste heat steam generator 18 according to the invention by opening the control valves 63 and 80, so that increasingly hot feed water is pressed into the steam drum 56 and into the low pressure evaporator heating surfaces 50.
  • their temperature can be kept at a value which will certainly prevent them from evaporating.
  • the remaining heat of the exhaust gases of the gas turbine at the cold end of the heat recovery steam generator 18 is used as far as possible. This also increases the supply of feed water from the feed water preheating heating surfaces 52.
  • evaporation of the economizer heating surfaces 46 can be avoided by opening the control valve 67 behind the feed water pump 64 and the reducing valve 70 installed between the outlet of the economizer heating surfaces 46 and the water-steam separation vessel 72.
  • further hot feed water can be fed from the economiser heating surfaces via the reducing valve 70 into the water-steam separating vessel 72 at the entrance to the reheater heating surfaces 40, so that the amount of reheated steam can also be increased.
  • the feed water which has not yet evaporated and which is separated in this water-steam separation vessel 72 passes via the overflow line 73 and the reducing valve 74 into the water-steam separation vessel 76 which is connected upstream of the low-pressure superheater heating surfaces 48.
  • the evaporated part of this feed water is dried in the low-pressure superheater heating surfaces 48 at the somewhat low pressure level, thus increasing the amount of low-pressure steam.
  • the excess feed water collecting at the bottom of the water-steam separation vessel 76 is fed into the condensate line 34 via the drain line 77 and the further adjustable reducing valve 78 and preheats the feed water.
  • the inventive arrangement of the economizer heating surfaces 46 in the temperature range of the low-pressure superheater heating surfaces 48 increases the temperature at the outlet of the economizer heating surfaces 46, so that warmer water is fed into the high-pressure evaporator heating surfaces 44 and their water-steam separating vessel 54 during nominal load operation . This increases the amount of high pressure steam generated. This shifting of the economizer heating surfaces 46 into a higher temperature range is only possible, however, because the further measures according to the invention effectively prevent the same from evaporating out in partial load operation.
  • this circuit not only prevents evaporation of the economizer heating surfaces 46 and feedwater preheating heating surfaces 52 when the power plant output is reduced, but also, because of the increased outlet temperature at the economizer outlet, increased high-pressure steam and medium-pressure steam during nominal load operation can be generated and overall the efficiency of the gas and steam turbine power plant 1 is increased even at nominal load.

Description

Die Erfindung bezieht sich auf einen Abhitzedampferzeuger für ein Gas- und Dampfturbinenkraftwerk mit Hochdrucküberhitzer-Heizflächen, Zwischenüberhitzer-Heizflächen, Hochdruckverdampfer-Heizflächen, Niederdrucküberhitzer-Heizflächen, Niederdruckverdampfer-Heizflächen und Economiser-Heizflächen.The invention relates to a heat recovery steam generator for a gas and steam turbine power plant with high-pressure superheater heating surfaces, reheater heating surfaces, high-pressure evaporator heating surfaces, low-pressure superheater heating surfaces, low-pressure evaporator heating surfaces and economiser heating surfaces.

Gas- und Dampfturbinenkraftwerke enthalten üblicherweise einen in der Abgasleitung hinter der Gasturbine eingebauten Abhitzedampferzeuger. In diesen Abhitzedampferzeugern wird die fühlbare Wärme der die Gasturbine verlassenden Abgase zur Dampferzeugung herangezogen. Mit dem erzeugten Dampf wird ein Dampfturbinenkraftwerk betrieben. In dem Weg durch den Abhitzedampferzeuger geben die heißen Abgase der Gasturbine ihre Wärme an die diversen im Abhitzedampferzeuger eingebauten Heizflächen ab. Um die dort bei unterschiedlichen Temperaturniveaus anfallende Wärme optimal ausnutzen zu können, sind diese Heizflächen oft in Speisewasservorwärmer-Heizflächen, Economiser-Heizflächen, Niederdruckverdampfer-Heizflächen, Niederdrucküberhitzer-Heizflächen, Hochdruckverdampfer-Heizflächen, Zwischenüberhitzer-Heizflächen und Hochdrucküberhitzer-Heizflächen unterteilt und entsprechend der jeweils erforderlichen Betriebstemperatur mehr zum heißeren oder mehr zum kühleren Ende des Abhitzedampferzeugers hin angeordnet.Gas and steam turbine power plants usually contain a heat recovery steam generator installed in the exhaust pipe behind the gas turbine. In these heat recovery steam generators, the sensible heat of the exhaust gases leaving the gas turbine is used to generate steam. A steam turbine power plant is operated with the generated steam. In the path through the heat recovery steam generator, the hot exhaust gases from the gas turbine give off their heat to the various heating surfaces installed in the heat recovery steam generator. In order to optimally utilize the heat generated there at different temperature levels, these heating surfaces are often subdivided into feed water preheater heating surfaces, economiser heating surfaces, low-pressure evaporator heating surfaces, low-pressure superheater heating surfaces, high-pressure evaporator heating surfaces, intermediate superheater heating surfaces and high-pressure superheater heating surfaces required operating temperature more towards the hotter or more towards the cooler end of the heat recovery steam generator.

Auch ist es bekannt, am Ausang der Verdampferheizflächen der jeweiligen Druckstufen sogenannte Wasser-Dampf-Trenngefäße, meist in Form von Dampftrommeln oder sogenannten Flaschen, anzuschließen. In diesen wird das aus den Verdampferheizflächen auströmende Wasser-Dampf-Gemisch in Wasser und Dampf getrennt. Der Dampf gelangt vom oberen Ende des jeweiligen Wasser-Dampf-Trenngefäßes in die nachgeschalteten Überhitzer-Heizflächen.It is also known to connect so-called water-steam separation vessels, usually in the form of steam drums or so-called bottles, to the outlet of the evaporator heating surfaces of the respective pressure stages. The water-steam mixture flowing out of the evaporator heating surfaces is separated into water and steam in these. The steam reaches the downstream superheater heating surfaces from the upper end of the respective water-steam separation vessel.

Das Wasser wird über eine Umwälzpumpe vom unteren Ende des jeweiligen Wasser-Dampf-Trenngefäßes abgezogen und erneut wieder in die jeweilige Verdampferheizflächen zurückbefördert.The water is drawn off from the lower end of the respective water-steam separating vessel by means of a circulating pump and again conveyed back into the respective evaporator heating surfaces.

Wird die Leistung eines solchen Gas- und Dampfturbinenkraftwerks zurückgenommen, so hat das zur Folge, daß die Menge der Gasturbinenabgase weniger stark abnimmt als ihre Temperatur. Das wiederum hat zur Folge, daß die im Hochdruckbereich erzeugte Dampfmenge wesentlich stärker zurückgeht als die im Niederdruckbereich erzeugte Dampfmenge. Gleichzeitig nimmt die im unteren Temperaturbereich, das heißt für die Vorwärmung des Speisewassers, zur Verfügung stehende Wärmemenge nur wenig ab. Das relativ große Wärmeangebot im Mittel- und Niedertemperaturbereich kann dann in Verbindung mit der infolge der verringerten Frischdampfmenge verminderten Speisewasserflusses zu Ausdampfungen in den Economiser- und Niederdruckvorwärmer-Heizflächen führen, die diese gefährden und daher höchst unerwünscht sind. Gleichzeitig steigt die Abgastemperatur hinter dem Abhitzedampferzeuger bei gleichzeitiger Verschlechterung des Anlagewirkungsgrades auf extrem hohe Werte.If the output of such a gas and steam turbine power plant is reduced, the result is that the amount of gas turbine exhaust gases decreases less than their temperature. This in turn has the consequence that the amount of steam generated in the high pressure area declines much more than the amount of steam generated in the low pressure area. At the same time, the amount of heat available in the lower temperature range, i.e. for preheating the feed water, decreases only slightly. The relatively large supply of heat in the medium and low temperature range can then, in conjunction with the reduced feed water flow due to the reduced amount of live steam, lead to evaporation in the economiser and low-pressure preheater heating surfaces, which endanger them and are therefore highly undesirable. At the same time, the exhaust gas temperature behind the heat recovery steam generator rises to extremely high values while the efficiency of the system deteriorates.

Um ein Ausdampfen der Economiser-Heizflächen im Teillastbereich zu vermeiden, wurde die Economiser-Austrittstemperatur bisher auf einen sehr niedrigen Auslegungswert festgelegt und die Economiser-Heizflächen nahe dem kühlen Ende des Abhitzedampferzeugers, das heißt in Strömungsrichtung der Gasturbinenabgase noch hinter den Niederdruckverdampfer-Heizflächen, eingebaut. Die sich daraus ergebende Verminderung der maximal erzeugbaren Frischdampfmenge wurde in Kauf genommen.In order to prevent the economiser heating surfaces from evaporating in the partial load range, the economiser outlet temperature has previously been set to a very low design value and the economiser heating surfaces have been installed near the cool end of the heat recovery steam generator, i.e. behind the low-pressure evaporator heating surfaces in the direction of flow of the gas turbine exhaust gases . The resulting reduction in the maximum amount of live steam that could be generated was accepted.

Es ist auch bekannt, das Ausdampfen der Speisewasservorwärm-Heizflächen im Teillastbereich dadurch zu vermeiden, daß man im Abhitzedampferzeuger einen Gasbypass vorsieht, durch den die Gasturbinenabgase an diesen Heizflächen vorbei ins Freie entlassen werden können. Auch diese Maßnahme ist mit einem Verzicht auf die maximale Ausnutzung der in den Gasturbinenabgasen steckenden thermischen Energie verbunden.It is also known to avoid the evaporation of the feed water preheating heating surfaces in the partial load range by providing a gas bypass in the waste heat steam generator, through which the gas turbine exhaust gases can be released past these heating surfaces into the open. This measure is also waived connected to the maximum utilization of the thermal energy contained in the gas turbine exhaust gases.

Schließlich hat man in solchen Teillastsituationen schon das Speisewasser in den Speisewasservorwärm-Heizflächen höherer Geschwindigkeit umgewälzt, um ein Ausdampfen der Speisewasservorwärm-Heizflächen in solchen Teillastsituationen zu vermeiden. Diese Maßnahme ist nur in engen Grenzen praktikabel und bietet keinen Schutz für die Economiser-Heizflächen.Finally, in such partial load situations, the feed water has already been circulated in the feed water preheating heating surfaces at a higher speed in order to avoid evaporation of the feed water preheating heating surfaces in such part load situations. This measure is only practicable within narrow limits and offers no protection for the economiser heating surfaces.

Der Erfindung liegt daher die Aufgabe zugrunde, einen Weg zu weisen, wie die Economiser-Heizflächen im Nennlastbetrieb auf eine optimale Betriebstemperatur geregelt werden können und wie bei Teillastbetrieb dennoch ein Ausdampfen der Economiser-Heizflächen vermieden werden kann.The invention is therefore based on the object of showing a way in which the economiser heating surfaces can be regulated to an optimal operating temperature in the nominal load operation and how evaporation of the economiser heating surfaces can nevertheless be avoided in part-load operation.

Diese Aufgabe wird durch die Merkmale des Anspruchs 1 gelöst. Weitere vorteilhafte Ausbildungen der Erfindung sind den Ansprüchen 2 bis 7 zu entnehmen.This object is solved by the features of claim 1. Further advantageous embodiments of the invention can be found in claims 2 to 7.

Dadurch, daß die Economiser-Heizflächen erfindungsgemäß in Strömungsrichtung der Gasturbinenabgase vor den Niederdruckverdampfer-Heizflächen angeordnet sind und ausgangsseitig sowohl an den Hochdruckverdampfer-Heizflächen als auch über eine Ausgleichsleitung mit einem Reduzierventil an eine den Zwischenüberhitzer-Heizflächen dampfseitig vorgeschalteten Mitteldruck-Wasser-Dampf-Trenngefäß angeschlossen sind, wird erreicht, daß die Austrittstemperatur des Economisers bei Nennlast auf ein Niveau angehoben wird, der es den nachfolgenden Verdampfer-Heizflächen ermöglicht, vermehrt Dampf zu erzeugen. Zugleich wird aber ein Ausdampfen dieser Economiser-Heizflächen bei Teillastbetrieb dadurch vermieden, daß über die Ausgleichsleitung mit dem Reduzierventil dafür gesorgt wird, daß im Teillastbetrieb vermehrt Wasser durch den Economiser transportiert werden kann, wobei die überschüssige Wassermenge über die Ausgleichsleitung durch bloßes Öffnen des Reduzierventils in das den Zwischenüberhitzer-Heizflächen dampfseitig vorgeschaltete Mitteldruck-Wasser-Dampf-Trenngefäß weitergegeben werden können. Diese überschüssige Wassermenge erzeugt dort vermehrt Dampf, der in den Zwischenüberhitzer-Heizflächen aufgeheizt und als Mitteldruckdampf eingesetzt werden kann.Characterized in that the economiser heating surfaces are arranged according to the invention in the flow direction of the gas turbine exhaust gases in front of the low-pressure evaporator heating surfaces and on the output side both on the high-pressure evaporator heating surfaces and via a compensating line with a reducing valve to a medium-pressure water-steam separating vessel upstream of the reheater heating surfaces are connected, it is achieved that the economizer's outlet temperature is raised to a level at nominal load which enables the subsequent evaporator heating surfaces to generate more steam. At the same time, however, evaporation of these economiser heating surfaces during part-load operation is avoided by ensuring that the equalization line with the reducing valve ensures that more water can be transported through the economiser in part-load operation, with the excess amount of water via the equalization line simply by opening the reducing valve in the reheater heating surfaces Medium-pressure water-steam separation vessel upstream on the steam side can be passed on. This excess amount of water generates more steam there, which can be heated in the reheater heating surfaces and used as medium pressure steam.

In besonders vorteilhafter Ausgestaltung der Erfindung können die Economiser-Heizflächen und die Niederdrucküberhitzer-Heizflächen im gleichen Temperaturbereich des Abhitzedamferzeugers eingebaut sein. Durch diese Maßnahme wird die Austrittstemperatur des Speisewassers am Ausgang der Economiser-Heizflächen auf einen Wert angehoben, der es später den Hochdruckverdampfer-Heizflächen ermöglicht, in maximalen Mengen Dampf zu erzeugen.In a particularly advantageous embodiment of the invention, the economiser heating surfaces and the low-pressure superheater heating surfaces can be installed in the same temperature range of the heat recovery steam generator. This measure raises the outlet temperature of the feed water at the outlet of the economiser heating surfaces to a value which later enables the high-pressure evaporator heating surfaces to produce steam in maximum quantities.

In besonders zweckmäßiger Weiterbildung der Erfindung kann das Mitteldruck-Wasser-Dampf-Trenngefäß wasserseitig über eine Ablaufleitung mit einem Reduzierventil an einen den Niederdrucküberhitzer-Heizflächen dampfseitig vorgeschalteten Niederdruck-Wasser-Dampf-Trenngefäß angeschlossen sein. Durch diese Maßnahme wird erreicht, daß im Mitteldrucksystem überschüssiges Wasser in das Niederdruck-Wasser-Dampf-Trenngefäß durch Öffnen des Reduzierventils in der Ablaufleitung abgeleitet werden kann und wiederum dort für vermehrte Dampferzeugung sorgt.In a particularly expedient development of the invention, the medium-pressure water-steam separation vessel can be connected on the water side via an outlet line with a reducing valve to a low-pressure water-steam separation vessel upstream of the low-pressure superheater heating surfaces. This measure ensures that excess water can be drained into the low-pressure water-steam separating vessel in the medium-pressure system by opening the reducing valve in the drain line and in turn ensures increased steam generation there.

Weitere Einzelheiten der Erfindung werden anhand eines in der Figur dargestellten Ausführungsbeispiels erläutert. Es zeigt:
   Die Figur eine schematische Darstellung der Anordnung und Schaltung der einzelnen Heizflächen im Abhitzedampferzeuger eines Gas- und Dampfturbinenkraftwerks.Further details of the invention are explained with reference to an embodiment shown in the figure. It shows:
The figure is a schematic representation of the arrangement and circuit of the individual heating surfaces in the heat recovery steam generator of a gas and steam turbine power plant.

In der schematischen Darstellung der Figur erkennt man den Aufbau des erfindungsgemäßen Gas- und Dampfturbinenkraftwerks 1 bestehend aus einem Gasturbinenkraftwerksteil 2 und einem Dampfturbinenkraftwerksteil 4. Der Gasturbinenkraftwerksteil 2 umfaßt eine Gasturbine 6, einen von der Gasturbine angetriebenen Luftverdichter 8 und Generator 10 sowie eine zwischen Luftverdichter und Gasturbine angeordnete Brennkammer 12 mit einer separaten Brennstoffzuführung 14 und einer Abgasleitung 16 für die Abgase der Gasturbine 6. Diese Abgasleitung 16 ist an den Abhitzedampferzeuger 18 des Dampfturbinenkraftwerksteils 4 angeschlossen. Der Dampfturbinenkraftwerksteil 4 umfaßt den Abhitzedampferzeuger 18, eine dampfseitig am Abhitzedampferzeuger angeschlossene dreigehäusige Dampfturbine 20 mit einem Hochdruckteil 22, einem Mitteldruckteil 24 und einem Niederdruckteil 26 und einen auf der gleichen Welle 28 sitzenden Generator 30. Ausgangsseitig ist am Niederdruckteil 26 der Dampfturbine 20 ein Kondensator 32 angeschlossen, welcher über eine Kondensatleitung 34 und eine Kondensatpumpe 36 an einen Speisewasserbehälter 38 angeschlossen ist.The schematic representation of the figure shows the structure of the gas and steam turbine power plant 1 according to the invention consisting of a gas turbine power plant part 2 and a steam turbine power plant part 4. The gas turbine power plant part 2 comprises a gas turbine 6, an air compressor driven by the gas turbine 8 and generator 10 and a combustion chamber 12 arranged between the air compressor and the gas turbine with a separate fuel feed 14 and an exhaust gas line 16 for the exhaust gases of the gas turbine 6. This exhaust gas line 16 is connected to the waste heat steam generator 18 of the steam turbine power plant part 4. The steam turbine power plant part 4 comprises the heat recovery steam generator 18, a three-casing steam turbine 20 connected on the steam side to the heat recovery steam generator with a high-pressure part 22, a medium-pressure part 24 and a low-pressure part 26 and a generator 30 seated on the same shaft 28. On the low-pressure part 26, the steam turbine 20 has a capacitor connected, which is connected via a condensate line 34 and a condensate pump 36 to a feed water tank 38.

Im Abhitzedampferzeuger 18 sind von der heißen zur kalten Seite hin nacheinander die nachfolgenden Heizflächen angeordnet: Am heißen Ende sind im gleichen Temperaturniveau Zwischenüberhitzer-Heizflächen 40 und Hochdrucküberhitzer-Heizflächen 42 angeordnet, ihnen folgen Hochdruckverdampfer-Heizflächen 44 und diesen wiederum Economiser-Heizflächen 46 und Niederdrucküberhitzer-Heizflächen 48, die beide ebenfalls im gleichen Temperaturniveau angeordnet sind. Diesen wiederum folgen Niederdruckverdampfer-Heizflächen 50 und diesen wiederum Speisewasservorwärm-Heizflächen 52. Die Hochdruck- und Niederdruckverdampfer-Heizflächen sind eingangsseitig und ausgangsseitig an je einem Wasser-Dampf-Trenngefäß - im Ausführungsbeispiel je einer Dampftrommel 54, 56 - angeschlossen. An der unteren Abzugsleitung einer jeden Dampftrommel 54, 56 sorgt je eine Umwälzpumpe 58, 60 dafür, daß das Speisewasser von der jeweiligen Dampftrommel in die zugehörige Verdampfer-Heizfläche und wieder in dieselbe Dampftrommel zurückbefördert wird.In the heat recovery steam generator 18, the following heating surfaces are arranged one after the other from the hot to the cold side: at the hot end, reheater heating surfaces 40 and high-pressure superheater heating surfaces 42 are arranged at the same temperature level, followed by high-pressure evaporator heating surfaces 44 and these in turn economizer heating surfaces 46 and low-pressure superheaters -Heating surfaces 48, both of which are also arranged at the same temperature level. These in turn are followed by low-pressure evaporator heating surfaces 50 and these, in turn, feed water preheating heating surfaces 52. The high-pressure and low-pressure evaporator heating surfaces are connected on the inlet and outlet sides to a water / steam separating vessel - in the exemplary embodiment a steam drum 54, 56 each. On the lower discharge line of each steam drum 54, 56, a circulation pump 58, 60 ensures that the feed water is conveyed from the respective steam drum into the associated evaporator heating surface and back into the same steam drum.

Der Speisewasserbehälter 38 ist über eine Speisewasserumwälzpumpe 62 mit nachgeschaltetem Regelventil 63 mit den Speisewasservorwärm-Heizflächen 52 verbunden, wobei diese Speisewasservorwärm-Heizflächen ausgangsseitig wiederum über ein weiteres Regelventil 65 in den Speisewasserbehälter 38 münden. Außerdem ist der Speisewasserbehälter 38 über eine mit einer Speisewasserpumpe 64 mit nachgeschaltetem Regelventil 67 ausgerüstete Speisewasserleitung 66 an die Economiser-Heizflächen 46 angeschlossen. Diese sind ausgangsseitig über ein Regelventil 68 mit dem Wasser-Dampf-Trenngefäß 54 der Hochdruckverdampfer-Heizflächen 44 verbunden. Darüber hinaus sind die Economiser-Heizflächen 46 ausgangsseitig über ein verstellbares Reduzierventil 70 an einem weiteren Wasser-Dampf-Trenngefäß 72 angeschlossen, welches dampfseitig den Zwischenüberhitzer-Heizflächen 40 vorgeschaltet ist und wasserseitig über ein weiteres verstellbares Reduzierventil 74 an ein zweites Wasser-Dampf-Trenngefäß 76 angeschlossen ist. Letzteres ist dampfseitig an den Eingang der Niederdrucküberhitzer-Heizflächen 48 angeschlossen. Wasserseitig ist das Wasser-Dampf-Trenngefäß 76 über ein weiteres verstellbares Reduzierventil 78 an den Speisewasserbehälter 38 angeschlossen. Auch die Speisewasservorwärm-Heizflächen 52 sind ausgangsseitig über ein Regelventil 80 an das als Dampftrommel 56 ausgebildete Wasser-Dampf-Trenngefäß der Niederdruckverdampfer-Heizflächen 50 angeschlossen. Diese Dampftrommel 56 der Niederdruckverdampfer-Heizflächen 50 ist dampfseitig an die Niederdrucküberhitzer-Heizflächen 48 und diese wiederum sind ausgangsseitig an den Niederdruckteil 26 der Dampfturbine 20 angeschlossen. Das als Dampftrommel 54 ausgebildete Wasser-Dampf-Trenngefäß der Hochdruckverdampfer-Heizflächen 44 ist dampfseitig an die Hochdrucküberhitzer-Heizflächen 42 und diese wiederum ausgangsseitig an den Hochdruckteil 22 der Dampfturbine 20 angeschlossen. Der Hochdruckteil 22 der Dampfturbine 20 ist ausgangsseitig bei A an den Eingang der Zwischenüberhitzer-Heizflächen 40 und diese wiederum sind ausgangsseitig an den Eingang des Mitteldruckteils 24 der Dampfturbine angeschlossen. Ausgangsseitig ist der Mitteldruckteil der Dampfturbine wie schon die Niederdrucküberhitzer-Heizflächen 48 an den Eingang des Niederdruckteils 26 der Dampfturbine angeschlossen.The feed water tank 38 is connected to the feed water preheating heating surfaces 52 via a feed water circulation pump 62 with a downstream control valve 63, these feed water preheating heating surfaces on the output side, in turn, into the feed water tank 38 via a further control valve 65. In addition, the feed water tank 38 is connected to the economizer heating surfaces 46 via a feed water line 66 equipped with a feed water pump 64 with a downstream control valve 67. On the output side, these are connected to the water-steam separation vessel 54 of the high-pressure evaporator heating surfaces 44 via a control valve 68. In addition, the economizer heating surfaces 46 are connected on the output side via an adjustable reducing valve 70 to a further water-steam separating vessel 72, which is connected upstream of the reheater heating surfaces 40 on the steam side, and on the water side via a further adjustable reducing valve 74 to a second water-steam separating vessel 76 is connected. The latter is connected on the steam side to the input of the low-pressure superheater heating surfaces 48. On the water side, the water-steam separation vessel 76 is connected to the feed water tank 38 via a further adjustable reducing valve 78. The feed water preheating heating surfaces 52 are also connected on the output side via a control valve 80 to the water-steam separating vessel of the low-pressure evaporator heating surfaces 50 which is designed as a steam drum 56. This steam drum 56 of the low-pressure evaporator heating surfaces 50 is connected to the low-pressure superheater heating surfaces 48 on the steam side, and these in turn are connected on the output side to the low-pressure part 26 of the steam turbine 20. The water-steam separating vessel of the high-pressure evaporator heating surfaces 44, which is designed as a steam drum 54, is connected on the steam side to the high-pressure superheater heating surfaces 42 and this in turn is connected on the outlet side to the high-pressure part 22 of the steam turbine 20. The high-pressure part 22 of the steam turbine 20 is connected on the output side at A to the input of the reheater heating surfaces 40, and these in turn are connected on the output side to the input of the medium-pressure part 24 of the steam turbine. On the output side, the medium-pressure part of the steam turbine, like the low-pressure superheater heating surfaces 48, is connected to the inlet of the low-pressure part 26 of the steam turbine.

Beim Betrieb des Gas- und Dampfturbinenkraftwerks 1 wird über den von der Gasturbine 6 angetriebenen Luftverdichter 8 Frischluft in die Brennkammer 12 der Gasturbine 6 gedrückt und dort zusammen mit dem über die Brennstoffzuführung 14 zugeführten Brennstoff verbrannt. Die heißen Verbrennungsgase entspannen sich in der Gasturbine 6, treiben diese und den Generator 10 und den Luftverdichter 8 an. Die aus der Gasturbine ausströmenden heißen Abgase durchströmen den Abhitzedampferzeuger 18 in der Darstellung der Figur von unten nach oben. Dort geben sie zunächst ihre Wärme an die Hochdrucküberhitzer- und Zwischenüberhitzer-Heizflächen 40, 42, sodann an die Hochdruckverdampfer-Heizflächen 44, anschließend an die Economiser- und Niederdrucküberhitzer-Heizflächen 46, 48, sodann an die Niederdruckverdampfer-Heizflächen 50 und zuletzt an die Speisewasservorwärm-Heizflächen 52 ab bevor sie in den Abgaskamin 17 entweichen können.During operation of the gas and steam turbine power plant 1, fresh air is pressed into the combustion chamber 12 of the gas turbine 6 via the air compressor 8 driven by the gas turbine 6 and burned there together with the fuel supplied via the fuel feed 14. The hot combustion gases relax in the gas turbine 6, drive it and the generator 10 and the air compressor 8. The hot exhaust gases flowing out of the gas turbine flow through the heat recovery steam generator 18 from the bottom to the top in the illustration of the figure. There they first give their heat to the high pressure superheater and reheater heating surfaces 40, 42, then to the high pressure evaporator heating surfaces 44, then to the economizer and low pressure superheater heating surfaces 46, 48, then to the low pressure evaporator heating surfaces 50 and finally to the Feed water preheating heating surfaces 52 before they can escape into the exhaust stack 17.

Das Speisewasser im Speisewasserbehälter 38 wird durch die Speisewasserumwälzpumpe 62 in die Speisewasservorwärm-Heizflächen 52, wo es aufgeheizt wird, und von dort wieder zurück in den Speisewasserbehälter gepumpt. Über die Speisewasserpumpe 64 wird außerdem Speisewasser in die Economiser-Heizflächen 46 gedrückt, dort aufgeheizt und weiter über die Speisewasserleitung 66 und das Regelventil 68 in das als Hochdrucktrommel 54 ausgebildete Wasser-Dampf-Trenngefäß der Hochdruckverdampfer-Heizflächen 44 befördert. Wasserseitig ist an dieser Hochdrucktrommel 54 eine Umwälzpumpe 58 angeschlossen, die das Speisewasser in die Hochdruckverdampfer-Heizflächen 44 und wieder zurück in die Hochdrucktrommel 54 pumpt. Dabei erhitzt sich das Speisewasser so stark, daß ein Teil des Speisewassers als Dampf in die Hochdrucktrommel 54 gelangt, dort von dem übrigen Speisewasser abgetrennt wird und über die Hochdruckdampfleitung 82 in die Hochdrucküberhitzer-Heizflächen 42 und von diesen in den Hochdruckteil 22 der Dampfturbine strömt. Der Abdampf der Hochdruckdampfturbine 22 strömt bei A in die Zwischenüberhitzer-Heizflächen 40 am heißen Ende des Abhitzedampferzeugers 18, wird in diesen Zwischenüberhitzer-Heizflächen auf annähernd die gleiche Temperatur aufgeheizt wie der Hochdruckdampf in den Hochdrucküberhitzer-Heizflächen 42 und gelangt so getrocknet als Mitteldruckdampf an den Eingang des Mitteldruckteils 24 der Dampfturbine 20 und vom Mitteldruckteil der Dampfturbine in den Niederdruckteil 26 der Dampfturbine und von dort wiederum in den Kondensator 32. Das Kondensat aus dem Kondensator wird über die Kondensatpumpe 36 in den Speisewasserbehälter 38 befördert.The feed water in the feed water tank 38 is pumped by the feed water circulation pump 62 into the feed water preheating heating surfaces 52, where it is heated, and from there back into the feed water tank. Via the feed water pump 64, feed water is also pressed into the economizer heating surfaces 46, heated there and further conveyed via the feed water line 66 and the control valve 68 into the water-steam separating vessel of the high-pressure evaporator heating surfaces 44 designed as a high-pressure drum 54. On the water side, a circulation pump 58 is connected to this high-pressure drum 54, which pumps the feed water into the high-pressure evaporator heating surfaces 44 and back into the high-pressure drum 54. The feed water heats up so strongly that part of the feed water reaches the high pressure drum 54 as steam, is separated there from the rest of the feed water and flows via the high pressure steam line 82 into the high pressure superheater heating surfaces 42 and from there into the high pressure part 22 of the steam turbine. The exhaust steam from the high-pressure steam turbine 22 flows at A into the reheater heating surfaces 40 at the hot end of the waste heat steam generator 18, and is in these The reheater heating surfaces are heated to approximately the same temperature as the high-pressure steam in the high-pressure superheater heating surfaces 42 and are thus dried as medium-pressure steam at the inlet of the medium-pressure part 24 of the steam turbine 20 and from the medium-pressure part of the steam turbine into the low-pressure part 26 of the steam turbine and from there again in the Condenser 32. The condensate from the condenser is conveyed into the feed water tank 38 via the condensate pump 36.

Wird nun bei diesem Gas- und Dampfturbinenkraftwerk 1 die Leistung der Gasturbine 6 zurückgenommen, so vermindert sich in erster Linie die Temperatur der in den Abhitzedampferzeuger 18 einströmenden Gasturbinenabgase, so daß die Heizleistung in den Zwischenüberhitzer- und Überhitzer-Heizflächen des Hochdrucksystems gegenüber der Heizleistung in den kühleren Teilen des Abhitzedampferzeugers überproportional zurückgeht. Nunmehr würde die Gefahr bestehen, daß infolge der verringerten Dampferzeugung und folglich geringeren Speisewasserflusses bei kaum verminderter Heizleistung im Niederdruckbereich die Economiser-Heizflächen 46 und auch die Speisewasservorwärm-Heizflächen 52 ausdampfen. Dieses soll aus Gründen der thermischen Überlastung dieser Heizflächen unbedingt vermieden werden. Um dies zu vermeiden, kann nunmehr beim erfindungsgemäßen Abhitzedampferzeuger 18 der Fluß durch die Speisewasservorwärm-Heizflächen 52 durch Öffnen der Regelventile 63 und 80 erhöht werden, so daß vermehrt heißes Speisewasser in die Dampftrommel 56 und in die Niederdruckverdampfer-Heizflächen 50 gedrückt wird. Infolge der so verstärkten Speisewasserströmung durch die Speisewasservorwärm-Heizflächen 52 kann deren Temperatur auf einem Wert gehalten werden, der ein Ausdampfen derselben mit Sicherheit vermeidet. Zugleich wird so auch die restliche Wärme der Abgase der Gasturbine am kalten Ende des Abhitzedampferzeugers 18 weitestgehend ausgenutzt. Außerdem verstärkt sich so auch das Angebot an Speisewasser aus den Speisewasservorwärm-Heizflächen 52.If the power of the gas turbine 6 is now reduced in this gas and steam turbine power plant 1, the temperature of the gas turbine exhaust gases flowing into the heat recovery steam generator 18 is reduced, so that the heating power in the reheater and superheater heating surfaces of the high pressure system compared to the heating power in the cooler parts of the heat recovery steam generator disproportionately. There would now be a risk that the economizer heating surfaces 46 and also the feed water preheating heating surfaces 52 evaporate due to the reduced steam generation and consequently lower feed water flow with hardly any reduction in heating power in the low pressure range. This should be avoided due to the thermal overload of these heating surfaces. In order to avoid this, the flow through the feed water preheating heating surfaces 52 can now be increased in the waste heat steam generator 18 according to the invention by opening the control valves 63 and 80, so that increasingly hot feed water is pressed into the steam drum 56 and into the low pressure evaporator heating surfaces 50. As a result of the feed water flow through the feed water preheating heating surfaces 52 thus increased, their temperature can be kept at a value which will certainly prevent them from evaporating. At the same time, the remaining heat of the exhaust gases of the gas turbine at the cold end of the heat recovery steam generator 18 is used as far as possible. This also increases the supply of feed water from the feed water preheating heating surfaces 52.

In ähnlicher Weise kann ein Ausdampfen der Economiser-Heizflächen 46 vermieden werden, indem das Regelventil 67 hinter der Speisewasserpumpe 64 und das zwischen dem Ausgang der Economiser-Heizflächen 46 und dem Wasser-Dampf-Trenngefäß 72 eingebaute Reduzierventil 70 geöffnet werden. Hierdurch kann weiteres heißes Speisewasser aus den Economiser-Heizflächen über das Reduzierventil 70 in das Wasser-Dampf-Trenngefäß 72 am Eingang der Zwischenüberhitzer-Heizflächen 40 eingespeist werden, so daß auch die Menge des zwischenüberhitzten Dampfes gesteigert werden kann. Das in diesem Wasser-Dampf-Trenngefäß 72 abgesonderte, noch nicht verdampfte Speisewasser gelangt über die Überströmleitung 73 und das Reduzierventil 74 in das Wasser-Dampf-Trenngefäß 76, das den Niederdrucküberhitzer-Heizflächen 48 vorgeschaltet ist. Hier wiederum wird auf dem etwas niederem Druckniveau der verdampfte Teil dieses Speisewassers in den Niederdrucküberhitzer-Heizflächen 48 getrocknet und vermehrt so die Niederdruckdampfmenge. Das sich am Boden des Wasser-Dampf-Trenngefäßes 76 ansammelnde, überschüssige Speisewasser wird über die Ablaufleitung 77 und das weitere verstellbare Reduzierventil 78 in die Kondensatleitung 34 eingespeist und wärmt das Speisewasser vor.Similarly, evaporation of the economizer heating surfaces 46 can be avoided by opening the control valve 67 behind the feed water pump 64 and the reducing valve 70 installed between the outlet of the economizer heating surfaces 46 and the water-steam separation vessel 72. As a result, further hot feed water can be fed from the economiser heating surfaces via the reducing valve 70 into the water-steam separating vessel 72 at the entrance to the reheater heating surfaces 40, so that the amount of reheated steam can also be increased. The feed water which has not yet evaporated and which is separated in this water-steam separation vessel 72 passes via the overflow line 73 and the reducing valve 74 into the water-steam separation vessel 76 which is connected upstream of the low-pressure superheater heating surfaces 48. Here, in turn, the evaporated part of this feed water is dried in the low-pressure superheater heating surfaces 48 at the somewhat low pressure level, thus increasing the amount of low-pressure steam. The excess feed water collecting at the bottom of the water-steam separation vessel 76 is fed into the condensate line 34 via the drain line 77 and the further adjustable reducing valve 78 and preheats the feed water.

Durch die erfindungsgemäße Anordnung der Economiser-Heizflächen 46 im Temperaturbereich der Niederdrucküberhitzer-Heizflächen 48 wird die Temperatur am Ausgang der Economiser-Heizflächen 46 angehoben, so daß bei Nennlastbetrieb wärmeres Wasser in die Hochdruckverdampfer-Heizflächen 44 und deren Wasser-Dampf-Trenngefäß 54 eingespeist wird. Dies vergrößert die Menge des erzeugten Hochdruckdampfes. Dieses Versetzen der Economiser-Heizflächen 46 in einen höheren Temperaturbereich ist aber nur möglich, weil ein Ausdampfen derselben im Teillastbetrieb durch die weiteren erfindungsgemäßen Maßnahmen wirkungsvoll verhindert wird. So wird im Teillastbetrieb die Gefahr, daß die Economiser-Heizflächen in diesem relativ heißen Bereich des Abhitzedampferzeugers ausdampfen dadurch beseitigt, daß durch Öffnen des Reduzierventils 70 zum Wasser-Dampf-Trenngefäß 72 hin der Fluß durch die Economiser-Heizflächen in dem Maße erhöht werden kann wie das Wärmeangebot bzw. die Speisewassertemperatur am Ausgang der Economiser-Heizflächen steigt. Dies wiederum hat zur Folge, daß nunmehr vermehrt Dampf in die Zwischenüberhitzerheizflächen 40 und vermehrt heißes Speisewasser über die Überströmleitung 73 und das Reduzierventil 74 in das zweite Wasser-Dampf-Trenngefäß 76 vor den Niederdrucküberhitzer-Heizflächen 48 strömt. Dadurch gelangt auch mehr Dampf in die Niederdrucküberhitzer-Heizflächen 48. Außerdem wird so auch vermehrt heißes Speisewasser aus dem zweiten Wasser-Dampf-Trenngefäß 76 vor den Niederdrucküberhitzer-Heizflächen 48 über die Ablaufleitung 77 in die Kondensatleitung 34 eingespeist und so die Temperatur im Speisewasserbehälter 38 erhöht. Das wiederum führt zu einem Ansteigen der Temperatur am Eingang der Economiser-Heizflächen 46 mit der Folge einer weiteren Zunahme des Flusses durch die Economiser-Heizflächen und einer weiteren Zunahme der Dampfströmung durch die Zwischenüberhitzer-Heizflächen und Niederdrucküberhitzer-Heizflächen.The inventive arrangement of the economizer heating surfaces 46 in the temperature range of the low-pressure superheater heating surfaces 48 increases the temperature at the outlet of the economizer heating surfaces 46, so that warmer water is fed into the high-pressure evaporator heating surfaces 44 and their water-steam separating vessel 54 during nominal load operation . This increases the amount of high pressure steam generated. This shifting of the economizer heating surfaces 46 into a higher temperature range is only possible, however, because the further measures according to the invention effectively prevent the same from evaporating out in partial load operation. In partial load operation, the risk that the economiser heating surfaces evaporate in this relatively hot area of the heat recovery steam generator is eliminated by opening the reducing valve 70 to the water-steam separating vessel 72 the flow through the economiser heating surfaces can be increased to the extent that the heat supply or the feed water temperature at the exit of the economiser heating surfaces increases. This in turn has the result that more steam now flows into the intermediate superheater heating surfaces 40 and more hot feed water via the overflow line 73 and the reducing valve 74 into the second water-steam separating vessel 76 in front of the low-pressure superheater heating surfaces 48. As a result, more steam also reaches the low-pressure superheater heating surfaces 48. In addition, more hot feed water from the second water-steam separating vessel 76 is fed into the condensate line 34 via the drain line 77 in front of the low-pressure superheater heating surfaces 48, and thus the temperature in the feed water container 38 elevated. This in turn leads to an increase in the temperature at the entrance of economizer heating surfaces 46, with the result of a further increase in the flow through the economizer heating surfaces and a further increase in steam flow through the reheater heating surfaces and low pressure superheater heating surfaces.

Es hat sich darüber hinaus gezeigt, daß durch diese Schaltung nicht nur ein Ausdampfen der Economiser-Heizflächen 46 und Speisewasservorwärm-Heizflächen 52 bei Zurücknahme der Kraftwerksleistung vermieden werden kann, sondern daß darüber hinaus auch wegen der erhöhten Austrittstemperatur am Economiserausgang vermehrt Hochdruckdampf und Mitteldruckdampf bei Nennlastbetrieb erzeugt werden kann und insgesamt der Wirkungsgrad des Gas- und Dampfturbinenkraftwerks 1 auch bei Nennlast erhöht wird.It has also been shown that this circuit not only prevents evaporation of the economizer heating surfaces 46 and feedwater preheating heating surfaces 52 when the power plant output is reduced, but also, because of the increased outlet temperature at the economizer outlet, increased high-pressure steam and medium-pressure steam during nominal load operation can be generated and overall the efficiency of the gas and steam turbine power plant 1 is increased even at nominal load.

Claims (7)

  1. Waste-heat steam generator for a gas and steam turbine power plant with high-pressure superheater heating surfaces, intermediate superheater heating surfaces, high-pressure vaporizer heating surfaces, low-pressure superheater heating surfaces, low-pressure vaporizer heating surfaces and economizer heating surfaces, characterized in that the economizer heating surfaces (46) are arranged, in the flow direction of the gas-turbine exhaust gases, in front of the low-pressure vaporizer heating surfaces (50) and on the output side are connected both to the high-pressure vaporizer heating surfaces (44) and by way of an equalizing pipe with a reducing valve (70) to a medium-pressure, water and steam separating vessel (72) connected in series on the steam side with the intermediate superheater heating surfaces (40).
  2. Waste-heat steam generator according to claim 1, characterized in that the economizer heating surfaces (46) and the low-pressure superheater heating surfaces (48) are arranged in the waste-heat steam generator (18) in the region of the same gas temperature.
  3. Waste-heat steam generator according to claim 1, characterized in that the economizer heating surfaces (46) are arranged, in addition, in the flow direction of the gas-turbine exhaust gases, in front of the low-pressure superheater heating surfaces.
  4. Waste-heat steam generator according to one or more of claims 1 to 3, characterized in that the medium-pressure, water and steam separating vessel (72) is attached on the water side by way of a waste pipe (73) with reducing valve (74) to a low-pressure, water and steam separating vessel (76) connected in series on the steam side with the low-pressure superheater heating surfaces (48).
  5. Waste-heat steam generator according to one or more of claims 1 to 4, characterized in that the low-pressure, water and steam separating vessel (76) is attached to the feed-water container (38) on the water side by way of a waste pipe (77) with reducing valve (78).
  6. Waste-heat steam generator according to one or more of claims 1 to 5, characterized in that the economizer heating surfaces (46) are arranged, in the flow direction of the gas-turbine exhaust gases, after the high-pressure vaporizer heating surfaces (44).
  7. Waste-heat steam generator according to one or more of claims 1 to 6, characterized in that the heating surfaces of the waste-heat steam generator (18) which are last in the flow direction of the gas-turbine exhaust gases are condensate preheater heating surfaces (52).
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DD296733A5 (en) 1991-12-12
DE59000787D1 (en) 1993-03-04

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