JPH11201684A - Heat-transfer pie supporting structure body of steam generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent condensing phenomenon of supplied water by suppressing occurrence of a dry-out region at a heat-transfer pipe supporting part, related to an egg-crate type heat-transfer pipe supporting structure body of a heat exchanger type steam generator. SOLUTION: Related to a pipe supporting structure body 10 of a steam generator, a first band-plate group comprising structure band-plates 11 spaced from each other and extending parallel and a second band-plate group comprising structure band-plates 13 extending parallel, to each other, with an interval are provided, the structure band-plates 11 and the structure band-plates 13 cross one another at right angles while inserted among others and form a grid- like structure body, a plurality of heat-transfer pipes 5 are received in a square cross-section grid space of the grid-like structure body for supporting, and the structure band-plates 11 and 13 forming the square cross-section grid space are provided with round holes 18 close to a supporting part of the heat-transfer pipe 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam generator, and more particularly to a structure for supporting a heat transfer tube.

[0002]

2. Description of the Related Art FIG. 4 shows a conceptual structure of a steam generator for a pressurized water reactor which is an example of a heat exchanger type steam generator. In brief, a large number of inverted U-shaped heat transfer tubes 5 are provided in the body 3 of the steam generator 1 to form a heat transfer tube bundle. The heat transfer tube bundle is supported by an egg crate (egg support frame) type support structure 7 which is arranged at intervals in the vertical direction. The high-temperature reactor coolant flows into one end of the heat transfer tube 5 from the lower inlet water chamber, descends after rising, and flows out from the other end to the outlet water chamber. The water supply flows in from the upper water supply ring header 8, descends outside the wrapper tube 9, turns over on the tube sheet, and rises while being heated in the heat transfer tube bundle. The generated steam passes through the steam separator and the moisture separator, becomes dry steam, and flows out from the upper portion.

FIG. 5 shows the structure of an egg crate type support structure 7. The linear portions of the heat transfer tubes 5 are arranged at a square pitch, and the transverse band plate 7a and the vertical band plate 7b are inserted into each other to form a strength support structure. Extending between five. Traversing strip 7a
The longitudinal band plate 7b and the spacer plate 7c maintain the space between the heat transfer tubes 5c, which are easily vibrated, to prevent mutual interference, and the transverse band plate 7a and the longitudinal band plate 7b form a strong frame structure. To support the heat transfer tube bundle against large lateral loads such as during an earthquake. Therefore, the width is relatively wide in order to secure required strength. Such a heat transfer tube 5 and a transverse strip 7
The geometrical relationship with a or the longitudinal strip 7b is shown in FIG. In particular, as shown in the plan view of FIG. 6A, a narrow portion is provided between the outer surface of the heat transfer tube 5 and the traversing strip 7 a or the longitudinal strip 7 b in the vicinity of the contact supporting portion 5 a of the heat transfer pipe 5. A space or clevis space is formed.

[0004]

However, since the amount of water supplied through the clevis space is limited, when it is heated and becomes steam, it flows as shown by an arrow in FIG. 7, and the water flows into the center thereof. Difficult. Therefore, a dry-out area D is formed on the downstream side of the feedwater flow, that is, on the upper portion of the horizontal strip 7a or the vertical strip 7b. Or damage to the support structure. Horizontal band 7a or vertical band 7
If the width of b is reduced, the generation of the dry-out region D is suppressed, but this causes another problem that the strength of the support structure is reduced and a large lateral load cannot be sufficiently supported. Therefore, an object of the present invention is to provide a heat transfer tube support structure of a steam generator that can suppress the occurrence of a dry-out region in a clevis space without reducing the strength and prevent the concentration phenomenon of feedwater.

[0005]

According to the present invention, there is provided, in accordance with the present invention, a first group of strips comprising first strips extending in parallel at a distance from one another and at a distance from each other. A second strip group of second strips extending in parallel to each other, wherein the first strip and the second strip intersect at right angles to each other and are inserted into each other to form a lattice-shaped structure. And an egg crate type heat transfer tube support structure that receives and supports one or a plurality of heat transfer tubes in the rectangular cross-section lattice space of the lattice-shaped structure is a first cross-section defining a rectangular cross-section lattice space.
An opening is formed in the second band plate in the vicinity of the support portion for the heat transfer tube. Preferably, narrow first and second heat transfer tube spacing holding plates are disposed between the first band plates and between the second band plates, respectively, and the opening is The first and second heat transfer tube spacing plates are formed at positions that do not interfere with the first heat transfer tube spacing plate and the second heat transfer tube spacing plate, and are defined in cooperation with the heat transfer tubes. We are facing the clevis space.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, the same parts are denoted by the same reference numerals, including the drawings related to the above-mentioned conventional technology. Referring first to FIG. 1, the straight legs of an inverted U-shaped heat transfer tube 5 are arranged at a so-called square pitch, which is supported by a tube support structure 10 according to the present invention. Since the number of the heat transfer tubes 5 is generally about 45,000 or less, FIG. 1 shows only a small part thereof. However, it should be understood that the number of heat transfer tubes 5 will increase or decrease depending on the required capacity of the steam generator. The tube support structure 10 comprises a transverse structural strip 11
And the longitudinally extending structural strips 13 are mutually inserted and assembled to form an egg crate-shaped structure. The width of the structural strips 11 and 13 is such that the tube support structure 10 can have the required rigidity and strength. Further, a narrow spacer plate 15 is provided between adjacent structural strips 11.
Are provided so as to extend between the respective tube rows, and are supported by being sandwiched between slits of the intersecting structural strips 13. Similarly, a narrow spacer plate 17 is provided between adjacent structural strips 13.
Are provided so as to extend between the respective tube rows, and are supported by being sandwiched between slits of the intersecting structural strips 11. However,
The spacer plates 15 and 17 cross each other, but are not fixed to each other. Furthermore, relatively wide structural strips 11,
13 has a round hole 1 at the center in the width direction of the contact portion with the heat transfer tube 5.
8 are drilled. Further, the structural strips 11 and 13 are formed with semicircular holes 19 at the intersection insertion portions of both.

FIG. 2 clearly shows the position of the round hole 18. As is readily apparent from the figure, the round hole 18 is located at a position that halves the contact length between the structural strip 11 and the heat transfer tube 5.
Although not shown, the position of the round hole 18 on the structural strip 13 is the same. In the pipe supporting structure 10 having such a structure, the water supply flows upward as in the case of the conventional one, but is particularly illustrated in FIG. Flows like so. That is, as shown in FIG. 3A, a crevis space 21 is defined near the contact portion C between the heat transfer tube 5 and the structural strip 11. Water (single-phase or two-phase) flows into the clevis space 21 as shown by a solid line arrow in FIG. 3B, and the generated steam flows out according to volume expansion as shown by a broken line arrow. There is a shortage of fluid near the contact part C,
Feed water flows through the round hole 18 of the present invention as indicated by the solid arrow, and steam flows out again as indicated by the dashed arrow.

[0008]

As described above, even if the feed water flowing through the clevis space adjacent to the contact portion between the heat transfer tube and the structural strip becomes steam and flows out to the side, the opening formed in the structural strip is formed. Since the feedwater flows into the clevis space anew, the occurrence of a dry-out region is suppressed, and the concentration phenomenon of the feedwater can be suppressed. In addition, since the width of the strip of the support structure is unchanged, the strength and rigidity are not reduced, and the support can be safely supported even if a large lateral load acts on the heat transfer tube bundle.

[Brief description of the drawings]

FIG. 1 is a partial perspective view showing a main part of an embodiment of the present invention.

FIG. 2 is a partial elevation view showing a part of FIG. 1 in an enlarged manner.

FIG. 3 is an operation explanatory diagram for explaining the operation of the embodiment.

FIG. 4 is a schematic vertical sectional view showing an example of a steam generator to which the present invention is applied.

FIG. 5 is a partial perspective view showing a conventional pipe support structure.

FIG. 6 is a three-side view showing an enlarged main part of FIG. 5;

FIG. 7 is an explanatory diagram for explaining a state of a problem of a conventional device.

[Explanation of symbols]

 Reference Signs List 5 heat transfer tube 10 tube support structure 11, 13 structural strip 15, 17 spacer plate 18 round hole 19 semicircular hole 21 clevis space

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[Procedure amendment]

[Submission date] May 12, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Correction contents]

FIG. 5 shows the structure of an egg crate type support structure 7. The linear portions of the heat transfer tubes 5 are arranged at a square pitch, and the transverse band plate 7a and the vertical band plate 7b are inserted into each other to form a strength support structure. Extending between five. Traversing strip 7a
The longitudinal band plate 7b and the spacer plate 7c maintain the space between the heat transfer tubes 5 that are easily vibrated to prevent mutual interference, and the transverse band plate 7a and the longitudinal band plate 7b form a strong frame structure. To support the heat transfer tube bundle against large lateral loads such as during an earthquake. Therefore, the width is relatively wide in order to secure required strength. Such a heat transfer tube 5 and a transverse strip 7
The geometrical relationship with a or the longitudinal strip 7b is shown in FIG. In particular, as shown in the plan view of FIG. 6A, a narrow portion is provided between the outer surface of the heat transfer tube 5 and the traversing strip 7 a or the longitudinal strip 7 b in the vicinity of the contact supporting portion 5 a of the heat transfer pipe 5. A space or clevis space is formed.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

According to the present invention, there is provided, in accordance with the present invention, a first group of strips comprising first strips extending in parallel at a distance from one another and at a distance from each other. And a second group of strips extending in parallel from each other , wherein the first strip and the second strip intersect each other.
Mutually plugged to form a grid-like structure with that, the lattice-shaped structure rectangular cross section, one for lattice space or plurality of heat transfer tubes accepted support to have egg crate type heat transfer tube support structure of the rectangular An opening is formed in the first and second strips that define the cross-sectional lattice space in the vicinity of the support portion with the heat transfer tube. Preferably, narrow first and second heat transfer tube spacing holding plates are disposed between the first band plates and between the second band plates, respectively, and the opening is The first and second heat transfer tube spacing plates are formed at positions that do not interfere with the first heat transfer tube spacing plate and the second heat transfer tube spacing plate, and are defined in cooperation with the heat transfer tubes. We are facing the clevis space.

Claims (3)

[Claims] 1. A first strip group consisting of first strips extending in parallel at intervals and a second strip group consisting of second strips extending in parallel at intervals. The first strip and the second strip intersect at right angles to each other and are inserted into each other to form a lattice-like structure, and one or more of the lattice-like structures have a rectangular cross-section lattice space. In a heat transfer tube support structure that receives and supports a plurality of heat transfer tubes,
A heat transfer tube support structure for a steam generator, characterized in that an opening is formed in the first and second strips defining the rectangular cross section lattice space in the vicinity of a support portion with the heat transfer tube. . 2. A narrow first heat transfer tube spacing plate is provided between the first strips, and a narrow second heat transfer tube gap is provided between the second strips. 2. The steam generator according to claim 1, wherein a holding plate is provided, and the opening is located at a position where the opening does not interfere with the first heat transfer tube spacing holding plate and the second heat transfer tube spacing holding plate. Heat tube support structure. 3. The opening according to claim 1, wherein the opening faces a clevis space defined by the first band plate or the second band plate in cooperation with the heat transfer tube. 3. The heat transfer tube support structure of the steam generator according to 2.