US3774579A - Method and apparatus for restarting boiler feed-water pump system - Google Patents

Method and apparatus for restarting boiler feed-water pump system Download PDF

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Publication number
US3774579A
US3774579A US00225806A US3774579DA US3774579A US 3774579 A US3774579 A US 3774579A US 00225806 A US00225806 A US 00225806A US 3774579D A US3774579D A US 3774579DA US 3774579 A US3774579 A US 3774579A
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United States
Prior art keywords
air separator
water
feed
boiler
plant
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Expired - Lifetime
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US00225806A
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English (en)
Inventor
A Sakai
T Teranishi
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Hitachi Ltd
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Hitachi Ltd
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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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D11/00—Feed-water supply not provided for in other main groups
    • F22D11/02—Arrangements of feed-water pumps

Definitions

  • ABSTRACT For a steam turbine plant including an air separator disposed in a feed-water heating cycle, there are pro- H vided a method and apparatus for restarting the plant so that the stable and reliable operations of the feedwater pump can be ensured.
  • FIG 3 FmuAux/L/ARY /6 smw CIRCUIT FROM TURBINE 8 BA 8* y C C G l4 l4 9 Q METHOD AND APPARATUS FOR RESTARTING BOILER FEED-WATER PUMP SYSTEM BACKGROUND OF THE INVENTION
  • two steamdriven feed-water pumps of 50 percent capacity and one or more than one motor-driven pumps of 20-25 percent capacity.
  • the steam-driven pumps are generally used in normal operation whereas the motor-driven pumps are used as reserve or for starting the plant.
  • the steam-driven pumps are in generally not used when there is not installed a special auxiliary boiler or the like because the sufficient steam cannot be fed to the steam-driven pumps. Therefore, in case of starting-up, the motordriven pumps are generally used.
  • the pressure in the air separator or deaerator remains at a level before the load is removed, and the water in the air separator, its downcomer and the suction pipes of the steam-driven pumps remains at a high temperature level before the load is removed. Therefore, when the feeding water into the boiler is started under these suspended conditions by the motor-driven pumps, the low-temperature water flows into the air separator (in this case, no vapor flows into the air separator) so that the pressure in the airseparator is suddenly dropped. Consequently, the temperature of water from the air separator is also dropped.
  • the high-temperature water still remains in the suction pipes of the steam-driven pumps, and vaporizes by itself as the pressure in the air separator is decreased, thus forming bubbles.
  • the pressure in the air separator is further decreased, the bubbles in the suction pipes of the steam-driven pumps are increased in volume and flow into the downcomer of the air separator.
  • the bubbles in the downcomer are cooled by the low-temperature water flowing from the air separator to the motor-driven pumps, and are collapsed, thus causing the water hammer.
  • the bubbles are entrained into the motor-driven pumps, and cause the cavitation thus causing the malfunction and destruction of the pumps.
  • FIGS. 1, 2 and 3 are diagrams of a first, second and third embodiments of the feed-pump starting apparatus in accordance with the present invention.
  • FIG. 4 is a graph used for explanation of the transient phenomena when a load is removed in the prior art plant.
  • reference numeral 1 designates a condenser; 2, a low-pressure feed-water heater; 3, a condenser tube; 4, an air separator or deaerator; 5, a downcomer; 6 and 7, a steam-driven feed-water pump and a motor-driven feed-water pump respectively; 8, a steam-driven pump suction tube; 9, a motordriven pump suction tube, these two suction tubes being in communication with the downcomer 5; 10, a feed pipe whose one end is connected to the steamdriven and motor-driven pumps 6 and 7 and whose the other end is connected to a boiler 12 through a highpressure feed-water heater 11; 13, a branch pipe branched from the suction tubes 8 and connected to the condenser tube 3; 14, a stop valve inserted in the branch pipe 13; 15, a circulation pump inserted in the branch pipe 13; 16, a bleeder tube interconnecting between the turbine (not
  • the second embodiment is different from the first embodiment illustrated in FIG. 1 in that in place of the circulation pump 15 or the first embodiment, a feed-water booster pump 20 is inserted in the suction tube 8, and the branch pipe 13 is branched from the discharge port of the pump 20 to be connected to the condenser tube 3.
  • the third embodiment of .the present invention is different from the. first and second embodiments thereof in that a branch pipe 13A is used to interconnect between the suction pipes 8 and the condenser 1 without the use of the circulation pump 15 or the feed-water booster pump 20 because the suction is provided by the condenser 1 in case of the restartingup of the steam electric power generation plant.
  • the pressures and temperatures in the air separator 4, the downcomer 5, and the steam-driven pump suction tubes 8 are maintained at the levels before the load was cut off.
  • the water is fed into the boiler 12 by the motordriven pump 7.
  • the heated steam will not be supplied to the air separator 4 but the low-temperature water from the condenser tube 3 is fed into the air separator 4.
  • the pressure in the air separator is gradually decreased as shown in FIG. 4, and consequently the pressure at the suction ports of the pumps 6 and 7 as well as the temperature of the water at the discharge port of the air separator 4 are also gradually decreased.
  • the pressure at the inlet ports of the pumps 6 and 7 are given by:
  • the stop valve 14 is simultaneously opened and the circulation pump 15 is also simultaneously started to flow the water entrapped in the suction pipes 8 through the branch pipe 13 into the condenser pipe 3 so that the water in the suction pipes 8 is replaced by the low-temperature water from the air separator 4.
  • the water hammer as well as the cavitation encountered in the prior art system will not occur.
  • both the steam-driven and motor-driven pumps are disposed, but in case of a small capacity steam electric power generation plant less than 250 MW, no steamdriven pump is in general provided and all pumps are of the motor-driven type.
  • the present invention may be advantageously applied also to such small-capacity plant and that any of the motor-driven pumps may be used for restarting-up. But it should be noted that all of the motor-driven pump suction pipes must be provided with branching pipes and stop valves.
  • the water hammer as well as the cavitation can be positively prevented, and the stable and reliable operation of the feed-water pumps can be ensured.
  • a method for restarting said feed-water pumps wherein, when said plant is restarted, the water entrapped in a circuit connecting said air separator to said feed-water pumps is discharged into said condenser.
  • a plant of the type comprising a condenser, an air separator, a boiler interconnected with one another by a piping system, and feed-water pumps inserted into the circuit interconnecting said air separator and said boiler, an apparatus comprising a branch pipe one end of which is connected to the circuit interconnecting said air separator and said feed-water pumps and the other end of which is connected to said condenser.
  • a method-for restarting said feed-water pumps wherein, when said plant is restarted, the water entrapped in a circuit connecting said air separator to said feed-water pumps is discharged into a circuit connected to said air separator.
  • the plant includes at least one stop valve means disposed in said circuit interconnecting said air separator and said boiler, and a circulation pump disposed in said circuit connected to said air separator, the method including selectively opening and closing said stop valve means to control the discharge of the entrapped water into said circuit connected to said air separator, and operating said circulation pump when said stop valve is opened to aid in discharging the entrapped water from said circuit interconnecting said air separator and said boiler.
  • the plant includes at least one stop valve means and at least one feed water booster pump means disposed in said circuit interconnecting said air separator and said boiler, the method including selectively opening and closing said stop valve means to control the discharge of the entrapped water into said circuit connected to said air separator, and operating said booster pump means when said stop valve is opened to aid in discharging the entrapped water from said circuit interconnecting said air separator and said boiler.
  • an apparatus comprising a branch pipe one end of which is connected to the circuit interconnecting said air separator and said feed-water pumps and the other end of which is connected to the circuit interconnecting said condenser and said air separator.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
US00225806A 1971-02-17 1972-02-14 Method and apparatus for restarting boiler feed-water pump system Expired - Lifetime US3774579A (en)

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Application Number Priority Date Filing Date Title
JP680771 1971-02-17

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US3774579A true US3774579A (en) 1973-11-27

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DE (1) DE2207227A1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5390631A (en) * 1994-05-25 1995-02-21 The Babcock & Wilcox Company Use of single-lead and multi-lead ribbed tubing for sliding pressure once-through boilers
US20110002193A1 (en) * 2006-03-21 2011-01-06 Eskild Storteig Active steering systems and methods for marine seismic sources
US20150000276A1 (en) * 2012-01-19 2015-01-01 Siemens Aktiengesellschaft Auxiliary steam generator system for a power plant

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4342003A1 (de) * 1993-12-09 1995-06-14 Abb Patent Gmbh Anordnung für die Speisewassereinspeisung in einem Kombikraftwerk
DE19809165C2 (de) * 1998-02-26 2001-11-22 Ver Energiewerke Ag Verfahren und Anordnung zum sicheren Betrieb einer Kesselspeisepumpe bei mit Gleit- oder Festdruck betriebenen Speisewasserbehälter für ein Dampfturbinen-Kraftwerk
JP7093319B2 (ja) 2019-02-21 2022-06-29 三菱重工業株式会社 汽力プラントの復水給水系統及び汽力プラント復水給水系統の運転方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3130715A (en) * 1962-02-27 1964-04-28 Worthington Corp Anti-flash control system
US3370573A (en) * 1966-12-12 1968-02-27 Combustion Eng Start-up system for combined circulation steam generator

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3130715A (en) * 1962-02-27 1964-04-28 Worthington Corp Anti-flash control system
US3370573A (en) * 1966-12-12 1968-02-27 Combustion Eng Start-up system for combined circulation steam generator

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5390631A (en) * 1994-05-25 1995-02-21 The Babcock & Wilcox Company Use of single-lead and multi-lead ribbed tubing for sliding pressure once-through boilers
US20110002193A1 (en) * 2006-03-21 2011-01-06 Eskild Storteig Active steering systems and methods for marine seismic sources
US20150000276A1 (en) * 2012-01-19 2015-01-01 Siemens Aktiengesellschaft Auxiliary steam generator system for a power plant
US9494054B2 (en) * 2012-01-19 2016-11-15 Siemens Aktiengesellschaft Auxiliary steam generator system for a power plant

Also Published As

Publication number Publication date
DE2207227A1 (de) 1972-08-24

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