EP0812407B1 - Process and system for starting a continuous steam generator - Google Patents

Process and system for starting a continuous steam generator Download PDF

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Publication number
EP0812407B1
EP0812407B1 EP96937994A EP96937994A EP0812407B1 EP 0812407 B1 EP0812407 B1 EP 0812407B1 EP 96937994 A EP96937994 A EP 96937994A EP 96937994 A EP96937994 A EP 96937994A EP 0812407 B1 EP0812407 B1 EP 0812407B1
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EP
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Prior art keywords
evaporator
evaporator tubes
water
steam generator
inlet
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EP96937994A
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German (de)
French (fr)
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EP0812407A1 (en
Inventor
Rudolf Kral
Joachim Franke
Helmuth Huschauer
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BBP Energy GmbH
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BBP Energy GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B29/00—Steam boilers of forced-flow type
    • F22B29/06—Steam boilers of forced-flow type of once-through type, i.e. built-up from tubes receiving water at one end and delivering superheated steam at the other end of the tubes
    • F22B29/12—Steam boilers of forced-flow type of once-through type, i.e. built-up from tubes receiving water at one end and delivering superheated steam at the other end of the tubes operating with superimposed recirculation during starting and low-load periods, e.g. composite boilers

Definitions

  • the invention relates to a method for starting a Continuous steam generator with the features of the preamble of Claim 1 and a start-up system with the features of The preamble of claim 2.
  • the heating leads from the gastight surrounding wall of a tube forming tubes of an evaporator to a complete evaporation of the Flow medium in the evaporator tubes in one pass.
  • a circulation current is superimposed. This is supposed to go through correspondingly high speeds in the pipes ensure this be cooled.
  • US-A-3 356 074 and GB-A-1 003 618 are forced steam generators with such a superimposed one Circulation known. This circulation flow is in one with a Check valve provided circulation line with the help of a Maintain circulation pump.
  • US-A-3 504 655 is a forced flow steam generator described in which in the start-up phase in the evaporator Natural circulation is generated.
  • the evaporator consists of two Evaporator tube groups that are flowed through in succession.
  • the Inlet collectors of the first evaporator tube group are over one Downpipe connected to a water-steam separator in which one connected to the output of an economizer Feed water pipe opens.
  • the exit collectors of the Evaporator tube groups are connected to the Water-steam separator connected. Furthermore, is about each a lockable line for the outlet collectors of the first Evaporator tube group with the inlet header of the second Evaporator tube group and the outlet header of the second Evaporator tube group connected to the secondary heating surfaces.
  • the outlet manifold via the water-steam separation vessel and the downpipe with the inlet collector according to Art be connected by communicating tube, so that in the Start-up phase of the mentioned natural circulation due to the Difference in pressure between the pressure head in the downpipe and the geodetic pressure drop in the evaporator tubes.
  • the disadvantage of the known forced-flow steam generator is that that a number of shut-off valves must be provided to the steam generator from natural circulation in the start-up phase and at Switch low load to forced through and vice versa.
  • the invention is therefore based on the object of a method to start up a once-through steam generator and a little specify complex start-up system in which on the one hand the Start-up losses are as low as possible and on the other hand enough water for the evaporator to safely cool the Evaporator tubes is supplied.
  • FIG. 1 An embodiment of the invention is based on a Drawing explained in more detail.
  • the figure shows schematically a continuous steam generator with vertical throttle cable and with a drain line of a start-up system.
  • the vertical throttle cable of the once-through steam generator 1 is through a Boundary wall 2 formed in at the lower end of the throttle cable a funnel-shaped bottom 3 merges.
  • the evaporator tubes 4 the surrounding wall 2 are gas-tight on its long sides connected to each other, e.g. B. welded.
  • the bottom 3 includes a discharge opening 3a, not shown, for ashes.
  • the lower area of the surrounding wall 2 forms the one with a number of burners 5 provided combustion chamber 6 of Continuous steam generator 1. The burners 5 is during the Operating a fuel line 7 via a fuel line 7 fed.
  • the medium side, d. H. of feed water or one Water / water-steam mixture, parallel from bottom to top - or in the case of evaporator tube groups in succession - flowed through Evaporator tubes 4 of the surrounding wall 2 are with their Entry ends to an entry collector 8 and with their Outlet ends connected to an outlet header 10.
  • the Entry collector 8 and exit collector 10 are located outside the throttle cable and are e.g. B, each by a annular tube formed.
  • the inlet header 8 is via a line 12 and one Collector 14 with the output of one in the once-through steam generator arranged high-pressure preheater or economizers 16 connected.
  • the heating surface of the economizer 16 is in one lying above the combustion chamber 6 and from the surrounding wall 2 enclosed space arranged.
  • the economizer 16 is on the input side via a collector 18 and a Feed water line 20 with a steam-heated one Heat exchanger 22 connected to the pressure side of a Feed water pump 24 is connected.
  • the suction side of the Feed water pump 24 is in a manner not shown and Way connected via a condenser to a steam turbine and thus switched into their water-steam cycle.
  • the outlet header 10 is connected to a via a line 26 Water-steam separation vessel or separator 28 connected. This in turn is on the steam side via a line 30 with an inlet header 32 of a high-pressure superheater 34, the inside the surrounding wall 2 between the economizer 16 and the combustion chamber 6 is arranged.
  • the high pressure superheater 34 is on the output side via a Collector 36 connected to a high pressure part of the steam turbine. Between the high pressure superheater 34 and the economizer 16 is enclosed within by the surrounding wall 2 Space provided an intermediate superheater 38, the over Collector 40, 42 between the high pressure part and a medium pressure part the steam turbine is switched.
  • the Economizer 16, the high pressure superheater 34 and the reheater 38 are in the so-called convection or bulkhead heating surfaces Convection train of the once-through steam generator 1.
  • the line 26 is part of a drain line 44, which is the outlet header 10 connects to the entry collector 8.
  • a drain line 44 is connected to a collector in the form of a bottle 46, connected to the separator 28 on the water side is.
  • a check valve 48 switched.
  • the preheated feed water S is in the economizer 16 further preheated and via line 12 to the inlet header 8 of the evaporator 4 supplied. Flowing through from there the heated feed water S the oblique, preferably however vertically arranged evaporator tubes 4 from bottom to top.
  • a water level d 1 is set in the discharge line 44, which is higher than a water level d 2 determined by the weight of the water and the water-steam mixture in the evaporator tubes 4.
  • the geodetic pressure drop in the evaporator tubes 4 is lower than the pressure level in the discharge line 44 from the outlet header 10 or from the bottle 46 to the evaporator 4.
  • This pressure difference causes the bottle 46 separated in the separator 28 to flow into the bottle 46 as required led water back to the evaporator inlet, ie to the inlet manifold 8 of the evaporator 4.
  • the water stream emerging from the economizer 16 is fed to the evaporator inlet, ie to the inlet manifold 8.
  • the pressure drop across the evaporator 4 becomes greater than the pressure level from the bottle 46 to the inlet manifold 8 of the evaporator 4. In this case, the water would flow in the opposite direction from the inlet header 8 into the bottle 46. This is prevented by the check valve 48.
  • the direct connection of the outlet collector 10 via the drain line 44 with the inlet header 8 of the evaporator 4 ensures a self-adjusting or regulating Circulating current.
  • the start-up losses are thus partially or completely recycle the excess water directly to the evaporator inlet 8 without a complex circulation pump kept simple and particularly low.

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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)
  • Heat Treatment Of Water, Waste Water Or Sewage (AREA)
  • Control Of Turbines (AREA)

Abstract

In a process for starting a continuous steam generator (1), through the evaporator tubes (4) of which water flows on the supply side from bottom to top, in order to prevent starting losses at least some of the water discharged from the evaporator tubes (4) on the outlet side is fed back into the inlet side. To this end there is a starting system with a discharge line (44) connecting the evaporator outlet (10) to the evaporator inlet (8).

Description

Die Erfindung bezieht sich auf ein Verfahren zum Anfahren eines Durchlaufdampferzeugers mit den Merkmalen des Oberbegriffes des Anspruches 1 sowie auf ein Anfahrsystem mit den Merkmalen des Oberbegriffes des Anspruches 2.The invention relates to a method for starting a Continuous steam generator with the features of the preamble of Claim 1 and a start-up system with the features of The preamble of claim 2.

In einem Durchlaufdampferzeuger führt die Beheizung von die gasdichte Umfassungswand einer Brennkanner bildenden Rohren eines Verdampfers zu einer vollständigen Verdampfung des Strömungsmediums in den Verdampferrohren in einem Durchgang. Üblicherweise wird dem Durchlaufstrom des Verdampfers - und häufig auch einem im Durchlaufdampferzeuger angeordneten rauchgas-beheizten Vorwärmer oder Economizer - während des Anfahrens ein Umlaufstrom überlagert. Dadurch sollen durch entsprechend hohe Geschwindigkeiten in den Rohren diese sicher gekühlt werden. Aus der US-A-3 356 074 und der GB-A-1 003 618 sind Zwangdurchdampferzeuger mit einem solchen überlagerten Umlauf bekannt. Dieser Umlaufstrom wird in einer mit einem Rückschlagventil versehenen Umlaufleitung mit Hilfe einer Umwälzpumpe aufrechterhalten.In a continuous steam generator, the heating leads from the gastight surrounding wall of a tube forming tubes of an evaporator to a complete evaporation of the Flow medium in the evaporator tubes in one pass. Usually the flow of the evaporator - and often also arranged in a once-through steam generator flue gas heated preheater or economizer - during the Starting a circulation current is superimposed. This is supposed to go through correspondingly high speeds in the pipes ensure this be cooled. From US-A-3 356 074 and GB-A-1 003 618 are forced steam generators with such a superimposed one Circulation known. This circulation flow is in one with a Check valve provided circulation line with the help of a Maintain circulation pump.

Wie aus der EP-B-0 054 601 bekannt ist, wird zum Anfahren und in einem unter einer bestimmten Grenzlast liegenden Lastbereich die Menge des von einer Speisepumpe zu fördernden Strömungsmediums vorzugsweise konstant gehalten. Dabei ist der Förderstrom der Speisepumpe gleich dem Verdampferdurchsatz. Bei dieser Betriebsweise sind die mit dem Zünden eines ersten Brenners des Durchlaufdampferzeugers beginnenden und mit Erreichen des Durchlaufbetriebs mit seinen hohen Dampftemperaturen endenden Anfahrzeiten sehr lang. Dies hat verhältnismäßig hohe Anfahrverluste zur Folge, da deren Höhe wesentlich von den Anfahrzeiten beeinflußt wird. As is known from EP-B-0 054 601, starting and in a load range below a certain limit load the amount of water to be pumped by a feed pump Flow medium preferably kept constant. Here is the Flow of the feed pump is equal to the evaporator throughput. At this mode of operation are those with the ignition of a first one Continuous steam generator burner starting and with Reaching throughput with its high Start-up times ending in steam temperatures are very long. this has relatively high start-up losses result because of their height is significantly influenced by the start-up times.

Hohe Anfahrverluste ergeben sich auch durch einen Wasserüberschuß. Dieser entsteht einerseits durch einen im Vergleich zur zugeführten Warme hohen Wassermassenstrom und zum anderen durch den sogenannten Wasserausstoß. Dieser wiederum entsteht, wenn die Verdampfung innerhalb der Verdampferheizfläche, beispielsweise in der Mitte des Verdampfers, beginnt und die stromabwärts vorhandene Wassermenge (Wasserpfropfen) ausschiebt. Bei der aus der EP-B-0 054 601 bekannten Durchlaufdampferzeugeranlage wird dieses Wasser in einem Abscheider oder Wasser-Dampf-Trenngefäß abgeschieden und in einen Speisewasserbehälter zurückgeführt. Dieses Konzept der Rückführung des überschüssigen Wassers erfordert allerdings ein aufwendiges Anfahrsystem mit einer Umwälzpumpe und/oder mit einem Ablaufsystem in den Speisewasserbehälter.High start-up losses also result from a Excess water. This is created on the one hand by an im Comparison to the supplied high water mass flow and others through the so-called water emission. This in turn arises when the evaporation inside the Evaporator heating surface, for example in the middle of the Evaporator begins and the downstream one Pushes out the amount of water (water plug). From the EP-B-0 054 601 known continuous steam generator plant this is Water in a separator or water-steam separator separated and returned to a feed water tank. This concept of returning excess water however requires a complex start-up system with a Circulation pump and / or with a drain system in the Feed water tank.

In der US-A-3 504 655 ist ein Zwangsdurchlaufdampferzeuger beschrieben, bei dem in der Anfahrphase in dem Verdampfer ein Naturumlauf erzeugt wird. Der Verdampfer besteht aus zwei Verdampferrohrgruppen, die hintereinander durchströmt sind. Die Eintrittssammler der ersten Verdampferrohrgruppe sind über ein Fallrohr mit einem Wasser-Dampf-Trenngefäß verbunden, in das eine an dem Ausgang eines Economizers angeschlossene Speisewasserleitung einmündet. Die Austrittssammler der Verdampferrohrgruppen sind über absperrbare Leitungen mit dem Wasser-Dampf-Trenngefäß verbunden. Weiterhin ist über jeweils eine absperrbare Leitung der Austrittssammler der ersten Verdampferrohrgruppe mit der Eintrittssammler der zweiten Verdampferrohrgruppe und der Austrittssammler der zweiten Verdampferrohrgruppe mit den Nachschaltheizflächen verbunden. Durch eine entsprechende Steuerung der Absperrventile können in der Anfahrphase die Austrittssammler über das Wasser-Dampf-Trenngefäß und das Fallrohr mit den Eintrittssammler nach Art von kommunizierenden Röhre verbunden werden, so daß sich in der Anfahrphase der erwähnte Naturumlauf aufgrund des Druckunterschiedes zwischen der Druckhöhe in dem Fallrohr und dem geodätischen Druckabfall in den Verdampferrohren einstellt. Der Nachteil des bekannten Zwanglaufdampferzeugers liegt darin, daß eine Anzahl von Absperrventilen vorgesehen werden muß, um den Dampferzeuger von Naturumlauf in der Anfahrphase und bei Schwachlast auf Zwangdurchlauf und umgekehrt umzustellen.In US-A-3 504 655 is a forced flow steam generator described in which in the start-up phase in the evaporator Natural circulation is generated. The evaporator consists of two Evaporator tube groups that are flowed through in succession. The Inlet collectors of the first evaporator tube group are over one Downpipe connected to a water-steam separator in which one connected to the output of an economizer Feed water pipe opens. The exit collectors of the Evaporator tube groups are connected to the Water-steam separator connected. Furthermore, is about each a lockable line for the outlet collectors of the first Evaporator tube group with the inlet header of the second Evaporator tube group and the outlet header of the second Evaporator tube group connected to the secondary heating surfaces. By appropriate control of the shut-off valves in the start-up phase, the outlet manifold via the water-steam separation vessel and the downpipe with the inlet collector according to Art be connected by communicating tube, so that in the Start-up phase of the mentioned natural circulation due to the Difference in pressure between the pressure head in the downpipe and the geodetic pressure drop in the evaporator tubes. The disadvantage of the known forced-flow steam generator is that that a number of shut-off valves must be provided to the steam generator from natural circulation in the start-up phase and at Switch low load to forced through and vice versa.

Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren zum Anfahren eines Durchlaufdampferzeugers und ein wenig aufwendiges Anfahrsystem anzugeben, bei dem einerseits die Anfahrverluste möglichst gering sind und bei dem andererseits dem Verdampfer genügend Wasser für eine sichere Kühlung der Verdampferrohre zugeführt wird.The invention is therefore based on the object of a method to start up a once-through steam generator and a little specify complex start-up system in which on the one hand the Start-up losses are as low as possible and on the other hand enough water for the evaporator to safely cool the Evaporator tubes is supplied.

Im Unterschied zu dem aus der US-A-3 504 655 bekannten Zwanglaufdampferzeuger wird gemäß der Erfindung das Speisewasser nach dem Austritt aus dem Economizer, der im Zwangsdurchlaufertenger angeordnet ist, dem Eintrittssammler am unteren Ende der Verdampferrohre über eine eigene Leitung und nicht dem Wasser-Dampf-Trenngefäß zugeführt. Dadurch reicht es aus, in der an das Wasser-Dampf-Trenngefäß angeschlossenen Ablaufleitung eine Rückschlagklappe vorzusehen, die ein Rückströmen vom Verdampfereintritt zum Verdampferaustritt verhindert. Darüber hinaus bestehen die mit der Erfindung erzielten Vorteile darin, daß durch die Rückführung des während des Anfahrens aus dem Verdampfer ausgestoßenen Wassers über eine Ablaufleitung zum Verdampfereintritt ein sich selbst regelnder Umlaufstrom erreicht und eine sichere Kühlung der Verdampferrohre gewährleistet ist.In contrast to that known from US-A-3 504 655 Forced steam generator according to the invention Feed water after the exit from the economizer, which is arranged in the forced flow filter, the Inlet collector at the lower end of the evaporator tubes via a own pipe and not the water-steam separator. This makes it sufficient to attach to the water-steam separation vessel to provide a check valve connected to the drain line, a backflow from the evaporator inlet to the Evaporator leakage prevented. In addition, there are with The invention achieved advantages in that Return of the evaporator during start-up ejected water via a drain line to the Evaporator inlet a self-regulating circulation flow reached and safe cooling of the evaporator tubes is guaranteed.

Ein Ausführungsbeispiel der Erfindung wird anhand einer Zeichnung näher erläutert. Darin zeigt die Figur schematisch einen Durchlaufdampferzeuger mit vertikalem Gaszug und mit einer Ablaufleitung eines Anfahrsystems.An embodiment of the invention is based on a Drawing explained in more detail. The figure shows schematically a continuous steam generator with vertical throttle cable and with a drain line of a start-up system.

Der vertikale Gaszug des Durchlaufdampferzeugers 1 gemäß der Erfindung mit rechteckigem Querschnitt ist durch eine Umfassungswand 2 gebildet, die am Unterende des Gaszugs in einen trichterförmigen Boden 3 übergeht. Die Verdampferrohre 4 der Umfassungswand 2 sind an ihren Längsseiten gasdicht miteinander verbunden, z. B. verschweißt. Der Boden 3 umfaßt eine nicht näher dargestellte Austragsöffnung 3a für Asche. Der untere Bereich der Umfassungswand 2 bildet die mit einer Anzahl von Brennern 5 versehene Brennkammer 6 des Durchlaufdampferzeugers 1. Den Brennern 5 wird während des Betriebs über eine Brennstoffleitung 7 ein Brennstoff B zugeführt.The vertical throttle cable of the once-through steam generator 1 according to the Invention with a rectangular cross-section is through a Boundary wall 2 formed in at the lower end of the throttle cable a funnel-shaped bottom 3 merges. The evaporator tubes 4 the surrounding wall 2 are gas-tight on its long sides connected to each other, e.g. B. welded. The bottom 3 includes a discharge opening 3a, not shown, for ashes. The lower area of the surrounding wall 2 forms the one with a number of burners 5 provided combustion chamber 6 of Continuous steam generator 1. The burners 5 is during the Operating a fuel line 7 via a fuel line 7 fed.

Die mediumseitig, d. h. von Speisewasser oder einem Wasser/Wasser-Dampf-Gemisch, von unten nach oben parallel - oder bei Verdampferrohrgruppen hintereinander - durchströmten Verdampferrohre 4 der Umfassungswand 2 sind mit ihren Eintrittsenden an einen Eintrittssammler 8 und mit ihren Austrittsenden an einen Austrittssammler 10 angeschlossen. Der Eintrittssammler 8 und der Austrittssammler 10 befinden sich außerhalb des Gaszugs und sind z. B, jeweils durch ein ringförmiges Rohr gebildet.The medium side, d. H. of feed water or one Water / water-steam mixture, parallel from bottom to top - or in the case of evaporator tube groups in succession - flowed through Evaporator tubes 4 of the surrounding wall 2 are with their Entry ends to an entry collector 8 and with their Outlet ends connected to an outlet header 10. The Entry collector 8 and exit collector 10 are located outside the throttle cable and are e.g. B, each by a annular tube formed.

Der Eintrittssammler 8 ist über eine Leitung 12 und einen Sammler 14 mit dem Ausgang eines in dem Durchlaufdampferzeuger angeordnetem Hochdruck-Vorwärmers oder Economizers 16 verbunden. Die Heizfläche des Economizers 16 ist in einem oberhalb der Brennkammer 6 liegenden und von der Umfassungswand 2 eingeschlossenen Raum angeordnet. Der Economizer 16 ist eingangsseitig über einen Sammler 18 und eine Speisewasserleitung 20 mit einem mittels Dampf D beheizten Wärmetauscher 22 verbunden, der an die Druckseite einer Speisewasserpumpe 24 angeschlossen ist. Die Saugseite der Speisewasserpumpe 24 ist in nicht näher dargestellter Art und Weise über einen Kondensator mit einer Dampfturbine verbunden und somit in deren Wasser-Dampf-Kreislauf geschaltet. The inlet header 8 is via a line 12 and one Collector 14 with the output of one in the once-through steam generator arranged high-pressure preheater or economizers 16 connected. The heating surface of the economizer 16 is in one lying above the combustion chamber 6 and from the surrounding wall 2 enclosed space arranged. The economizer 16 is on the input side via a collector 18 and a Feed water line 20 with a steam-heated one Heat exchanger 22 connected to the pressure side of a Feed water pump 24 is connected. The suction side of the Feed water pump 24 is in a manner not shown and Way connected via a condenser to a steam turbine and thus switched into their water-steam cycle.

Der Austrittssammler 10 ist über eine Leitung 26 mit einem Wasser-Dampf-Trenngefäß oder Abscheider 28 verbunden. Dieser wiederum ist dampfseitig über eine Leitung 30 mit einem Eintrittssammler 32 eines Hochdruck-Überhitzers 34 verbunden, der innerhalb der Umfassungswand 2 zwischen dem Economizer 16 und der Brennkammer 6 angeordnet ist. Der Hochdruck-Überhitzer 34 ist während des Betriebs ausgangsseitig über einen Sammler 36 mit einem Hochdruckteil der Dampfturbine verbunden. Zwischen dem Hochdruck-Überhitzer 34 und dem Economizer 16 ist innerhalb des von der Umfassungswand 2 eingeschlossenen Raumes ein Zwischenüberhitzer 38 vorgesehen, der über Sammler 40, 42 zwischen den Hochdruckteil und einen Mitteldruckteil der Dampfturbine geschaltet ist. Der Economizer 16, der Hochdruck-Überhitzer 34 und der Zwischenüberhitzer 38 liegen als Konvektions- oder Schottheizflächen im sogenannten Konvektionszug des Durchlaufdampferzeugers 1. The outlet header 10 is connected to a via a line 26 Water-steam separation vessel or separator 28 connected. This in turn is on the steam side via a line 30 with an inlet header 32 of a high-pressure superheater 34, the inside the surrounding wall 2 between the economizer 16 and the combustion chamber 6 is arranged. The high pressure superheater 34 is on the output side via a Collector 36 connected to a high pressure part of the steam turbine. Between the high pressure superheater 34 and the economizer 16 is enclosed within by the surrounding wall 2 Space provided an intermediate superheater 38, the over Collector 40, 42 between the high pressure part and a medium pressure part the steam turbine is switched. The Economizer 16, the high pressure superheater 34 and the reheater 38 are in the so-called convection or bulkhead heating surfaces Convection train of the once-through steam generator 1.

Die Leitung 26 ist Teil einer Ablaufleitung 44, die den Austrittssammler 10 mit dem Eintrittssammler 8 verbindet. In die Ablaufleitung 44 ist ein Sammler in Form einer Flasche 46 geschaltet, die mit dem Abscheider 28 wasserseitig verbunden ist. In die Ablaufleitung 44 ist außerdem eine Rückschlagklappe 48 geschaltet.The line 26 is part of a drain line 44, which is the outlet header 10 connects to the entry collector 8. In the Drain line 44 is connected to a collector in the form of a bottle 46, connected to the separator 28 on the water side is. In the drain line 44 is also a check valve 48 switched.

Während des Anfahrens des Durchlaufdampferzeugers 1 wird Speisewasser S über die Speisewasserpumpe 24 durch den Wärmetauscher 22 gefördert und dort zunächst vorgewärmt. Dabei kann die Menge des den Verdampferrohren 4 pro Zeiteinheit zugeführten Speisewassers S, d.h. der Speisewasserstrom, in Abhängigkeit von der Menge des den Brennern 5 pro Zeiteinheit zugeführten Brennstoffs B (Brennstoffstrom) eingestellt werden. Das so vorgewärmte Speisewasser S wird im Economizer 16 weiter vorgewärmt und über die Leitung 12 dem Eintrittssammler 8 des Verdampfers 4 zugeführt. Von dort ausgehend durchströmt das aufgeheizte Speisewasser S die schräg, vorzugsweise jedoch vertikal verlaufend angeordneten Verdampferrohre 4 von unten nach oben. Während des Anfahrvorgangs mit geringem Verdampfermassenstrom kommt es in den Verdampferrohren, d.h. in der Verdampferheizfläche, zur Verdampfung eines Teils des Speisewassers S. Dadurch wird das stromabwärts vorhandene Speisewasser S teilweise aus dem Verdampfer 4 in den Abscheider 28 ausgeschoben und fällt von dort in die Flasche 46 sowie von dort in die Ablaufleitung 44. Im Abscheider 28 abgeschiedener Dampf HD wird über die Leitung 30 dem Hochdruck-überhitzer 34 zugeführt und dort überhitzt.During the start-up of the continuous steam generator 1 Feed water S via the feed water pump 24 through the heat exchanger 22 promoted and preheated there. Here can the amount of the evaporator tubes 4 supplied per unit time Feed water S, i.e. the feed water flow, depending on the amount of burners 5 per unit time supplied fuel B (fuel flow) can be set. The preheated feed water S is in the economizer 16 further preheated and via line 12 to the inlet header 8 of the evaporator 4 supplied. Flowing through from there the heated feed water S the oblique, preferably however vertically arranged evaporator tubes 4 from bottom to top. During the start-up process with little Evaporator mass flow occurs in the evaporator tubes, i.e. in the evaporator heating surface, for evaporating a part of the feed water S. This makes the downstream Feed water S partially from the evaporator 4 in the separator 28 pushed out and falls from there into the bottle 46 as well thence to the drain line 44. Separated in the separator 28 Steam HD becomes the high pressure superheater via line 30 34 fed and overheated there.

In der Ablaufleitung 44 stellt sich ein Wasserstand d1 ein, der gegenüber einem durch das Gewicht des Wassers und des Wasser-Dampf-Gemisches in den Verdampferrohren 4 bestimmten Wasserstand d2 höher liegt. Dadurch ist in der Art kommunizierender Röhren der geodätische Druckabfall in den Verdampferrohren 4 geringer als die Druckhöhe in der Ablaufleitung 44 vom Austrittssammler 10 oder von der Flasche 46 zum Verdampfer 4. Durch diesen Druckunterschied strömt das im Abscheider 28 abgeschiedene und in die bedarfsweise vorgesehene Flasche 46 geführte Wasser zurück zum Verdampfereintritt, d.h. zum Eintrittssammler 8 des Verdampfers 4. Gleichzeitig mit diesem Umlaufstrom wird der aus dem Economizer 16 austretende Wasserstrom dem Verdampfereintritt, d.h. dem Eintrittssammler 8 zugeführt.A water level d 1 is set in the discharge line 44, which is higher than a water level d 2 determined by the weight of the water and the water-steam mixture in the evaporator tubes 4. As a result, in the manner of communicating tubes, the geodetic pressure drop in the evaporator tubes 4 is lower than the pressure level in the discharge line 44 from the outlet header 10 or from the bottle 46 to the evaporator 4. This pressure difference causes the bottle 46 separated in the separator 28 to flow into the bottle 46 as required led water back to the evaporator inlet, ie to the inlet manifold 8 of the evaporator 4. Simultaneously with this circulating stream, the water stream emerging from the economizer 16 is fed to the evaporator inlet, ie to the inlet manifold 8.

Sinkt der Wasserstand d1 in der Ablaufleitung 44 und liegt der Wasserstand d2 in den Verdampferrohren 4 über dem Niveau d1 in der Ablaufleitung 44, so wird der Druckabfall über dem Verdampfer 4 größer als die Druckhöhe von der Flasche 46 zum Eintritssammler 8 des Verdampfers 4. In diesem Fall würde das Wasser in umgekehrter Richtung vom Eintrittssammler 8 in die Flasche 46 strömen. Dies wird durch die Rückschlagklappe 48 verhindert.If the water level d 1 in the outlet line 44 drops and the water level d 2 in the evaporator tubes 4 is above the level d 1 in the outlet line 44, the pressure drop across the evaporator 4 becomes greater than the pressure level from the bottle 46 to the inlet manifold 8 of the evaporator 4. In this case, the water would flow in the opposite direction from the inlet header 8 into the bottle 46. This is prevented by the check valve 48.

Die direkte Verbindung des Austrittssammlers 10 über die Ablaufleitung 44 mit dem Eintrittssammler 8 des Verdampfers 4 gewährleistet einen sich selbst einstellenden oder regelnden Umlaufstrom. Somit werden die Anfahrverluste durch teilweises oder vollständiges Rückführen des überschüssigen Wassers direkt zum Verdampfereintritt 8 ohne aufwendige Umwälzpumpe in einfacher Art und Weise besonders gering gehalten. Gleichzeitig ist sichergestellt, daß dem Verdampfer stets genügend Wasser für die Kühlung der Verdampferrohre 4 zugeführt wird.The direct connection of the outlet collector 10 via the drain line 44 with the inlet header 8 of the evaporator 4 ensures a self-adjusting or regulating Circulating current. The start-up losses are thus partially or completely recycle the excess water directly to the evaporator inlet 8 without a complex circulation pump kept simple and particularly low. At the same time it is ensured that the evaporator is always sufficient Water for cooling the evaporator tubes 4 is supplied.

Claims (2)

  1. Method of starting up a forced throughflow steam generator with evaporator tubes, which are flowed through on the feedwater side in parallel and upwardly from below, wherein the water ejected from the evaporator tubes at the outlet end is fed back to the evaporator tubes at the inlet end by way of an outflow duct, which is connected to the evaporator tubes, as a self-regulating naturally circulating flow, which is maintained by the pressure difference between the pressure level in the outflow duct and the geodetic pressure decay in the evaporator tubes, characterised in that the feedwater after exit from an economiser is fed to the evaporator tubes at the lower end by way of a connecting duct and that a return flow in the outflow duct from the evaporator inlet to the evaporator outlet is prevented by a non-return valve.
  2. Start-up system for a forced throughflow steam generator (1) with a number of evaporator tubes (4) flowed through in parallel upwardly from below and an economiser (16) arranged in the forced throughflow steam generator (1), wherein an outflow duct (44) is provided, in which a water/steam separation container (28) is arranged, which connects an outlet collector (10) common to the evaporator tubes (4) with an inlet collector (8) common to the evaporator tubes (4) in the manner of communicating pipes, whereby a natural circulating flow is maintained by the pressure difference between the pressure level in the outflow duct (44) and the geodetic pressure decay in the evaporator tubes (4), characterised in that a non-return valve (48) is arranged in the outflow duct (44) and that a connecting duct (12) conducting feedwater is connected with the inlet collector (8) of the evaporator tubes (4) after the exit from the economiser (16).
EP96937994A 1995-09-08 1996-09-05 Process and system for starting a continuous steam generator Expired - Lifetime EP0812407B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19533351 1995-09-08
DE19533351 1995-09-08
PCT/DE1996/001666 WO1997009565A2 (en) 1995-09-08 1996-09-05 Process and system for starting a continuous steam generator

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EP0812407A1 EP0812407A1 (en) 1997-12-17
EP0812407B1 true EP0812407B1 (en) 2000-06-07

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EP96937994A Expired - Lifetime EP0812407B1 (en) 1995-09-08 1996-09-05 Process and system for starting a continuous steam generator

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EP (1) EP0812407B1 (en)
JP (1) JP2001507436A (en)
CN (1) CN1164889A (en)
AT (1) ATE193765T1 (en)
DE (1) DE59605404D1 (en)
DK (1) DK0812407T3 (en)
ES (1) ES2148810T3 (en)
WO (1) WO1997009565A2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102017205382A1 (en) * 2017-03-30 2018-10-04 Siemens Aktiengesellschaft Water return in vertical forced-circulation steam generators

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19800017C2 (en) * 1998-01-04 2001-04-26 Reinhard Leithner Method for operating a once-through steam generator
CN111802919B (en) * 2019-04-12 2022-07-15 华帝股份有限公司 Steam generator residual water discharge control method, steam generator and steam cooking equipment

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Publication number Priority date Publication date Assignee Title
DE944856C (en) * 1951-10-24 1956-06-28 Siemens Ag Procedure for the low-load operation of a once-through boiler
CH416676A (en) * 1962-10-30 1966-07-15 Mitsubishi Shipbuilding & Eng Device for the forced return of water through a once-through boiler
AT258316B (en) * 1964-02-28 1967-11-27 Siemens Ag Forced flow boiler
US3356074A (en) * 1965-07-12 1967-12-05 Combustion Eng Vapor generating organziation and method
US3504655A (en) * 1967-10-11 1970-04-07 Foster Wheeler Corp Natural circulation start-up system for once-through steam generator
US3580223A (en) * 1969-04-24 1971-05-25 Steinmueller Gmbh L & C Method and apparatus for operation of a positively driven steam generator with rolled overlap and gastight welded vaporizer walls
DE2735463C2 (en) * 1977-08-05 1982-03-04 Kraftwerk Union AG, 4330 Mülheim Continuous steam generator

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102017205382A1 (en) * 2017-03-30 2018-10-04 Siemens Aktiengesellschaft Water return in vertical forced-circulation steam generators

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JP2001507436A (en) 2001-06-05
ATE193765T1 (en) 2000-06-15
CN1164889A (en) 1997-11-12
DK0812407T3 (en) 2000-10-23
ES2148810T3 (en) 2000-10-16
EP0812407A1 (en) 1997-12-17
DE59605404D1 (en) 2000-07-13
WO1997009565A2 (en) 1997-03-13
WO1997009565A3 (en) 1997-04-03

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