JP4988622B2 - Water heater - Google Patents

Description

  The present invention relates to a feed water heater that preheats condensate condensed in a condenser with extraction from a steam turbine.

  The feed water heater is provided in a thermal power plant or a nuclear power plant, and is used for preheating the condensed water condensed by the condenser with the extraction of the steam turbine before introducing it to the boiler or the nuclear reactor. Thus, if the temperature of feed water is raised in advance by the feed water heater, the plant thermal efficiency can be improved. As a feed water heater, there are generally a low pressure feed water heater provided on the upstream side of a feed water pump and a high pressure feed water heater provided on the downstream side thereof.

  The high-pressure feed water heater has a water chamber header through which feed water that has been pressurized by a feed water pump and heated by extraction of a steam turbine flows. The water chamber header is mainly composed of a tube plate and a hemispherical water chamber end plate, and an internal space (water chamber) is divided into two by a water chamber partition plate joined to the tube plate and the water chamber end plate (base material). It is divided into two. Since the water supply pressurized by the water supply pump and heated by the steam flows through the water chamber during plant operation, the water chamber partition plate receives external force (load) from the water supply or the like. Since this load causes stress at the joint between the water chamber partition plate and the base material, it may cause fatigue cracking of the base material when it acts repeatedly over time.

  As a technique for reducing the stress acting on the base material in this way, a notch is provided in a part of the water chamber partition plate, and the water chamber partition plate and the member attached to the notch (the contact plate) Some have welded a base material (see Patent Document 1).

Japanese Patent Laid-Open No. 5-240406

  However, in the above technique, the part where the water chamber partition plate is joined to the base material via the contact plate is only a part of the water chamber partition plate, and the water chamber partition plate and the base material are directly connected to the other joints. It is joined. For this reason, the stress generated at a place other than the contact plate directly acts on the base material, and therefore, when the stress is concentrated at a place other than the contact plate, it is insufficient as a countermeasure against fatigue cracking of the base material.

  The objective of this invention is providing the feed water heater which can reduce the stress which generate | occur | produces in the junction part of a water chamber partition plate and a base material.

(1) In order to achieve the above object, the present invention provides a tube plate that supports a plurality of heating tubes for heating feed water, and a water chamber that is attached to the tube plate and forms a water chamber together with the tube plate. A mirror plate, a water chamber partition plate fixed in the water chamber, and attached to an outer edge portion of the water chamber partition plate, and joined to either or both of the tube plate and the water chamber mirror plate via a welded portion. And the rigidity of the mounting member is relatively low compared to the rigidity of the base material joined via the welded portion and the rigidity of the welded portion, and the mounting member includes the water chamber. It shall be attached to the whole outer edge part of a partition plate .

  When the water chamber partition plate is attached in this manner, the strength of the welded portion is relatively larger than the strength of the attachment member, and the stress generated in the welded portion during plant operation is relatively low in strength. Since it is distributed to the mounting member, the stress acting on the tube plate and the water chamber end plate can be reduced.

  (2) The attachment member of (1) is preferably formed in a pipe shape.

  (3) The diameter of the mounting member of (2) is preferably set such that the diameter of the mounting member is larger than the thickness of the water chamber partition plate.

  According to the present invention, since the stress generated at the joint between the water chamber partition plate and the base material is reduced, the durability and reliability of the water heater can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an overall structural diagram of a high-pressure feed water heater according to an embodiment of the present invention.
The high-pressure feed water heater shown in this figure includes a water chamber header 1 into which feed water (condensate) from a condenser (not shown) is introduced, and a body portion 2 through which bleed air from a steam turbine flows. .

  The water chamber header 1 includes a tube plate 11, a water chamber end plate 12, a water supply inlet nozzle 13, a water supply outlet nozzle 14, a water chamber manhole portion 15, and a water chamber partition plate 16.

  The tube plate 11 supports a plurality of heating tubes 21 for heating the feed water introduced into the water chamber header 1. The water chamber end plate 12 is a thick hemispherical portion welded to the tube plate 11 so as to be located on the opposite side of the body portion 2, and forms a water chamber 30 in the water chamber header 1 together with the tube plate 11. ing.

  A water supply inlet nozzle 13, a water supply outlet nozzle 14, and a water chamber manhole table 15 are welded to the water chamber end plate 12. The water supply inlet nozzle 13 is a part into which water supplied from the condenser is introduced, and the water supply outlet nozzle 14 is a part from which water heated by the steam is led out when passing through the heating pipe 21. The water chamber manhole table 15 is a portion used when an operator accesses the water chamber for inspection or the like.

  The water chamber partition plate 16 partitions the water chamber 30 and is fixed in the water chamber 30 via an attachment member 40 (see FIG. 2 later). The water chamber 30 is partitioned into an inlet water chamber 31 and an outlet water chamber 32 by the water chamber partition plate 16.

  The inlet water chamber 31 communicates with the water supply inlet nozzle 13 and is a portion into which the water supply whose pressure has been increased by a water supply pump (not shown) is introduced. The outlet water chamber 32 is in communication with the water supply outlet nozzle 14 and is a part through which the heated water passing through the heating pipe 21 is led out. The inlet water chamber 31 and the outlet water chamber 32 are connected via a plurality of heating pipes 21 arranged in the body 2.

  The trunk portion 2 is a portion that includes a plurality of heating tubes 21, and includes a steam inlet nozzle 22 and a drain outlet nozzle 23.

  The steam inlet nozzle 22 is a portion into which steam extracted from a steam turbine (not shown) is introduced, and is attached above the trunk portion 2. The drain outlet nozzle 23 is a portion from which water condensed by the water supply in the heating tube 21 is discharged, and is attached below the trunk portion 2. The steam introduced from the steam inlet nozzle 22 is heat-exchanged with the feed water flowing through the heating pipe 21 in the trunk portion 2 to become water, and is discharged to the outside through the drain outlet nozzle 23.

  2 is a structural view of the vicinity of the water chamber header 1 in the high-pressure feed water heater of FIG. 1, and FIG. 3 is an enlarged view of the vicinity of III in FIG. 2 (that is, the vicinity of the attachment member 40). In addition, the same code | symbol is attached | subjected to the same part as the previous figure, and description is abbreviate | omitted.

  The attachment member 40 shown in these drawings is for fixing the water chamber partition plate 16 to the tube plate 11 and the water chamber end plate 12, and is attached to the outer edge portion of the water chamber partition plate 16. The attachment member 40 is joined to the tube plate 11 and the water chamber end plate 12 which are base materials via a welded portion 41 (see FIG. 3).

  The shape of the attachment member 40 is formed such that the rigidity of the attachment member 40 is relatively lower than the rigidity of the base material (tube plate 11 and water chamber end plate 12) and the rigidity of the welded portion 41. The attachment member 40 of the present embodiment is formed of a thin pipe-shaped member that satisfies this rigidity condition, and is attached over the entire outer edge portion of the water chamber partition plate 16.

  The welded portion 41 is provided on both sides of the attachment member 40 with respect to the attachment member 40 in a state of being in contact with the tube plate 11 or the water chamber end plate 12. Since the water chamber partition plate 16 is welded via the attachment member 40 having the rigidity as described above, the strength of the welded portion 41 is relatively larger than the strength of the attachment member 40.

  Further, as shown in FIG. 3, the diameter R of the attachment member 40 of the present embodiment is set to be larger than the thickness T of the water chamber partition plate 16. Therefore, the distance L from the center plane C of the water chamber partition plate 16 to the welded portion 41 is larger than that when the water chamber partition plate 16 is directly welded to the tube plate 11 or the water chamber end plate 12.

  When the plant is operated with the feed water heater configured as described above, stress (for example, the water chamber partition plate 16 is applied to the welded portion 41 that is a joint portion between the tube plate 11 and the water chamber end plate 12 and the water chamber partition plate 16). Stress generated by restraining (fixing) in the water chamber 30, thermal stress generated by temperature change of the water supply, or stress generated by the differential pressure between the inlet water chamber 31 and the outlet water chamber 32 is generated.

  By the way, unlike this embodiment, when the water chamber partition plate 16 is directly welded to the tube plate 11 or the water chamber end plate 12, the stress generated in the welded portion is applied to the tube plate 11 or the water chamber end plate 12. Since it acts directly, there was a relatively high possibility that fatigue cracking would occur in the tube plate 11 and the water chamber end plate 12 when the feed water heater was used over time.

  On the other hand, the water chamber partition plate 16 in the present embodiment is welded to the tube plate 11 and the water chamber end plate 12 via the attachment member 40, and the rigidity of the attachment member 40 is the tube plate 11 and water. The rigidity of the end panel 12 and the rigidity of the welded portion 41 are set relatively low. When the water chamber partition plate 16 is attached via such an attachment member 40, the strength of the welded portion 41 is relatively greater than the strength of the attachment member 40. Thereby, since the stress which generate | occur | produces in the welding part 41 at the time of plant operation is disperse | distributed to the attachment member 40 with comparatively low intensity | strength, the stress which acts on the tube sheet 11 or the water chamber end plate 12 can be reduced. Thereby, since possibility that a stress crack will arise in the tube plate 11 and the water chamber end plate 12 can be reduced, durability and reliability of a water heater are improved.

  Further, since the diameter R of the mounting member 40 of the present embodiment is set larger than the thickness T of the water chamber partition plate 16, welding is performed from the center plane C of the water chamber partition plate 16 which is a neutral surface of the moment load. The distance to the portion 41 is larger than when the water chamber partition plate 16 is directly welded to the tube plate 11 or the like. When the mounting member 40 is formed in this way, it acts on the contact portion 41, the tube plate 11, and the water chamber end plate 12 (base material) as compared with the case where the molten water partition plate 16 is directly welded to the tube plate 11 or the like. The moment load is relatively relaxed. Thereby, the durability and reliability of the feed water heater are further improved.

  Furthermore, when the attachment member 40 is attached to the entire outer edge portion of the water chamber partition plate 16 as in the present embodiment, the base material during plant operation is compared with the case where the attachment member 40 is provided at a part of the outer edge portion. The stress acting on can be reduced. Unlike the present embodiment, an attachment member 40 is provided on a part of the outer edge of the water chamber partition plate 16, and the attachment member 40 is attached to either or both of the tube plate 11 and the water chamber end plate 12. You may join via. In this case, the stress reduction effect as described above is exhibited at the portion where the attachment member 40 is attached.

  In the above embodiment, the mounting member 40 is formed into a pipe shape, focusing on the ease of manufacturing and assembling the member. However, for example, a polygonal shape may be used. good. Moreover, as a shape of the attachment member 40 other than this, for example, a C-shaped one in which a part of the pipe material is cut out, or a bellows shape that expands and contracts according to a load acting on the water chamber partition plate 16 during plant operation. You may use things. When the attachment member 40 has a bellows shape as in the latter case, it is sufficient to provide one or more mountain folds (valley folds). In these cases, the thickness of the attachment member 40 is the same as the thickness of the water chamber partition plate 16 in order to make the attachment member 40 less rigid than the rigidity of the tube plate 11, the water chamber end plate 12, and the welded portion 41. It is preferable to set it to be less than the thickness of the water chamber partition plate 16.

The whole high-pressure feed water heater which is embodiment of this invention. FIG. 3 is a structural diagram in the vicinity of a water chamber header in the high-pressure feed water heater of FIG. 1. The enlarged view of III vicinity in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water chamber header 2 Body 11 Tube plate 12 Water chamber end plate 16 Water chamber partition plate 21 Heating tube 30 Water chamber 40 Mounting member 41 Welding part C Center plane of water chamber partition plate R Diameter of mounting member

Claims (3)

A tube plate supporting a plurality of heating tubes for heating the feed water;
A water chamber end plate attached to the tube plate and forming a water chamber with the tube plate;
A water chamber partition plate fixed in the water chamber;
It is attached to the outer edge of the water chamber partition plate, and includes an attachment member that is joined to either or both of the tube plate and the water chamber end plate via a welded portion,
The rigid mounting member is relatively rather low compared to the stiffness and rigidity of the welded portion of the base material to be bonded via the weld,
The water supply heater according to claim 1, wherein the attachment member is attached to the entire outer edge portion of the water chamber partition plate . The feed water heater according to claim 1,
The attachment water heater is characterized in that the attachment member is formed in a pipe shape. The feed water heater according to claim 2,
The diameter of the said attachment member is larger than the thickness of the said water chamber partition plate, The feed water heater characterized by the above-mentioned.

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