JP2001272183A - Condenser tube plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a condenser tube plate capable of preventing the generation of a residual stress near a welding line after welding in the condenser tube plate assembled through welding. SOLUTION: The condenser tube plate is prepared by a method wherein one end of a plurality of cooling tubes is attached and fixed to cooling tube holes provided on a tube plate divided into a plurality of pieces in predetermined arrays respectively, and, thereafter, a plurality of divided tube plates are connected to each other through welding to make the integrated tube plate. In such a tube plate, the predetermined array of the cooling tube holes is specified so as to be a square array in the first and second rows from the welding line of the welding connection while the arrays in rows after the second row are specified so as to be either one of an equilateral triangle array, an oblique triangle array or an oblique square array to reduce the stress concentration coefficient of the tube plate around the cooling tube hole of the first row, where the residual stress due to welding connection is concentrated and obtain a structure reduced in an acting actual residual stress whereby the problem of generation of SCC(stress corrosion crack) is resolved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condenser tube sheet in a nuclear power plant, a thermal power plant and the like.
In particular, the present invention relates to a condenser tube sheet having a structure for reducing stress concentration when a plurality of divided tube sheets are welded and joined.

[0002]

2. Description of the Related Art A conventional condenser tube sheet will be described with reference to FIGS. FIG. 7 is a sectional elevation view showing a general structure of a condenser in a nuclear power plant, a thermal power plant, and the like, and FIG. 8A is a tube plate of a water chamber as viewed from arrows XX in FIG. FIG. 8B is a schematic front view of FIG.
It is a middle YY arrow line view.

As shown in FIG. 7, a nuclear power plant,
In a condenser 1 in a thermal power plant or the like, a cooling pipe 5 is attached between respective tube plates 4 of an inlet-side water chamber 2 and an outlet-side water chamber 3, and cooling water such as seawater is supplied to the inlet-side water chamber 2. It is introduced, passes from the inlet side water chamber 2 to the outlet side water chamber 4 through the cooling pipe 5, and is discharged from the outlet side water chamber 4.

On the other hand, a low-pressure turbine 6 is provided above the condenser 1.
The steam sent from the low-pressure turbine 6 to the condenser 1 exchanges heat with the cooling pipe 5 to condense and become condensate.
It is discharged from the outlet pipe 7 at the bottom of the condenser 1.

A plurality of cooling pipes 5 are arranged inside the condenser 1 in parallel, and both ends of the cooling pipes 5 are fixed to the cooling pipe holes 8 of the tube sheets 4 on both sides. In the cooling pipe hole group area 4a indicated by hatching in the schematic front view of the plate 4, a large number of cooling pipes are provided in a predetermined pattern. is there.

[0006] Therefore, the size of the condenser 1 may be as large as 10 meters in the right and left directions and nearly 10 m in the vertical direction in FIG. 6, and it is difficult to carry the entire condenser into the installation site as a whole. There are cases in which the tube sheet 4 and the cooling pipe 5 are divided into a plurality of pieces, assembled, and then assembled after welding to the site after welding.

For example, as shown in FIG. 8 (a), the condenser 1 is divided into upper and lower parts, and the cooling pipes 5 are attached and fixed to the upper tube sheet 41 and the lower tube sheet 42, respectively. When welding to form an integral tube sheet 4, welding is performed from the surface on the side opposite to the side where the cooling pipe 5 is disposed. After welding, the upper tube sheet 41 and the lower tube sheet 42 are deformed by welding. As shown by a broken line in FIG. 8B, the upper and lower portions of the welding line 43 are about to be deformed so as to fall on the welding side.

However, since both the upper tube sheet 41 and the lower tube sheet 42 already have the cooling pipes 5 attached thereto, no deformation occurs in the cooling pipe hole group area 4a, and the upper pipe sheet 41 and the lower tube sheet 42 are located closest to the welding line 43 in the cooling pipe hole group area 4a. A great deal of deformation occurs in the tube sheet 4 near the cooling pipe hole 8-1 in the near row (first row), and a large deformation occurs, and the welding line 43 appears on the cooling pipe 5 side as a welding deformation δ. In addition, 1
A large residual stress F is applied to the tube sheet 4 around the cooling pipe hole 8-1 in the row.
Occurs, and depending on the tube sheet material, SCC (Str
ess Corrosion Crack (stress corrosion cracking) is a concern.

However, in the condenser 1, the cooling pipe 5
Is required to be arranged with a high density, and by reducing the predetermined arrangement or increasing the distance between the welding line 43 and the cooling pipe hole 8-1 in the first row, the effect of the residual stress F is increased. It was also difficult to avoid.

[0010]

According to the present invention, the condenser is divided into a plurality of parts as described above, and the divided pipe sheets and cooling pipes are assembled. In a condenser tube sheet to be assembled, a condenser tube capable of preventing a residual stress from being concentrated and generated on a tube sheet around a first-row cooling pipe hole close to a welding line of the welded tube sheet. It is an object to provide a board.

[0011]

Means for Solving the Problems (1) The present invention has been made to solve such problems, and the first aspect of the present invention has been made.
As a means of, after attaching and fixing one end of a plurality of cooling pipes to cooling pipe holes provided in a predetermined arrangement on a plurality of divided tube sheets, the divided tube sheets are welded to each other. In a condenser tube sheet formed as an integral tube sheet, the predetermined arrangement of the cooling pipe holes is set at a distance of 1 mm from a welding line of the weld joint.
A condensate arrangement wherein the array of the second and third columns is a regular square array, and the array of the second and subsequent columns is any one of a regular triangular array, a diagonal triangular array, and a diagonal square array. It is intended to provide a vessel plate.

According to the first means, the stress concentration coefficients in the tube sheet around the cooling pipe holes in the first row where the residual stress due to welding is concentrated are arranged in a regular square arrangement, so that a regular triangular arrangement and an oblique triangular arrangement are provided. , The effective residual stress acting is smaller than that of any one of the diagonal square arrangements, and all the cooling pipe holes are arranged in the same arrangement, regular triangular arrangement, diagonal triangular arrangement, diagonal square arrangement. The structure is further reduced as compared with one of the arrangements.

(2) As a second means, in the condenser tube sheet of the first means, the arrangement of the first and second rows is as follows:
Instead of the regular square array, a regular triangular array is used, and the second and subsequent columns are arranged in any one of the regular triangular array, the oblique triangular array, and the oblique square array. It is an object of the present invention to provide a condenser tube sheet characterized by being arranged in any one of a square arrangement.

According to the second means, the stress concentration coefficients in the tube sheet around the cooling pipe holes in the first row where the residual stress due to welding is concentrated are arranged in a regular triangular arrangement. The effective residual stress acting is smaller than that of any one of the arrangements, and all cooling pipe holes are arranged in any one of the same arrangement, diagonal triangular arrangement, diagonal square arrangement In addition, since the arrangement of the first and second rows is a regular triangular arrangement, the density of cooling pipe holes is higher than that of a regular square arrangement.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A condenser tube sheet according to a first embodiment of the present invention will be described with reference to FIGS. FIG.
FIG. 8 is an enlarged view of a portion corresponding to a portion near a welding line of an upper tube sheet 41 in the schematic front view of the tube sheet of FIG. In FIG. 1, the same parts as those of the above-described conventional one are denoted by the same reference numerals, to facilitate understanding of the present embodiment, and the description will be omitted, and different points from the conventional one will be mainly described. The upper tube sheet 41 and the lower tube sheet 42 have the same arrangement of the cooling tube holes 8 as the above-described conventional one, but the same reference numerals are used. This is the same in other embodiments described later.

In the above-described conventional device, the upper tube sheet 4
The residual stress F generated near the welding line 43 after welding the first and lower tubesheets 42 is concentrated around the cooling pipe hole 8-1 in the first row which is structurally closest to the welding line 43 and the second row. It has been found that the residual stress in the sample is extremely reduced. Based on it 1
If the effect of the residual stress around the cooling pipe holes in the rows is effectively reduced, the arrangement of the cooling pipes 5 having a high density as before can be achieved without greatly changing the configuration and arrangement of the tube sheet 4 and the cooling pipes 5. It has been found that the problems of the above-mentioned conventional apparatus can be solved while maintaining the same, and the inventors have invented a condenser tube sheet having an optimal arrangement of cooling pipe holes.

That is, in the first embodiment,
The arrangement of the cooling pipe holes 8-1 in the first row and the cooling pipe holes 8 in the second row is arranged in an arrangement form having a smaller stress concentration coefficient than the arrangement of the cooling pipe holes 8 in the second and subsequent rows. The tube sheet 4 (upper tube sheet 4) around the cooling pipe hole 8-1 in the first row where the residual stress is converted and concentrated.
1. The structure is such that the effective residual stress F acting on the lower tube sheet 42) is further reduced.

The stress concentration coefficient α acting when the holes are arranged in a predetermined manner in the plate material depends on the type of the arrangement of the holes 8 ′ with respect to the direction of the applied stress σ, and the diameter d and the pitch p of the holes 8 ′. There is a certain tendency.

FIG. 6 is an explanatory view of the type of arrangement corresponding to the direction of the applied stress σ when the holes 8 'having a fixed arrangement are provided in the plate material. As shown in FIG. 6 (a), holes 8 'having a diameter d are arranged at the vertices of a square at a pitch p and one side is oriented at right angles in the direction of the applied stress σ in a “square array” A, FIG. 6 (b) As shown in FIG. 6C, holes 8 'having a diameter d are arranged at the vertices of an equilateral triangle at a pitch p and one side is oriented at right angles in the direction of the applied stress σ as shown in FIG. , Diameter d
Holes 8 'are arranged at the vertices of an equilateral triangle at a pitch p, and one side is parallel to the load stress σ direction.
C, as shown in FIG. 6 (a), holes 8 'having a diameter d are arranged at the vertices of the square at a pitch p, and four sides are set in the direction of the applied stress σ.
The arrangement toward 5 ° is referred to as “diagonal square array” D, and is used in this specification as the name of each array.

In this case, the stress concentration coefficient αa in the regular square array A, the stress concentration coefficient αb in the regular triangular array B, the stress concentration coefficient αc in the diagonal triangular arrangement C, and the stress concentration coefficient αd in the diagonal square arrangement D are respectively represented by holes 8. The ratio becomes larger as the ratio (d / p) of the diameter d to the pitch p becomes larger, and in the same range (d / p) in all the ranges (d / p), there is a relationship of αa <αb <αc <αd. .

On the other hand, in order to increase the cooling efficiency and the density of the arrangement of the cooling pipes, the cooling pipe 5 of the condenser 1 has a small number of steam blow-ups in the vertical direction as shown in FIG. In many cases, a high regular triangular array B, a diagonal triangular array C or a diagonal square array D was used.

The present embodiment pays attention to such a point,
By appropriately arranging the cooling pipe holes 8, it is possible to reduce the stress concentration factor around the cooling pipe holes 8-1 in the first row near the welding line 43 without impairing the function of the conventional condenser 1. , To reduce the effective residual stress.

As shown in FIG. 1, specifically, when the arrangement of the cooling pipe holes 8 after the second row of cooling pipe holes 8 is a regular triangular array B, the cooling pipe holes 8-1 in the first row are arranged. The arrangement of the cooling pipe holes 8 in the second row and the cooling pipe holes 8 in the second row were converted into a regular square array A so that the stress concentration coefficient was smaller than that of the regular triangular array B of the cooling pipe holes 8 in the second row and thereafter. .

On the other hand, in FIG. 1, the pitch and diameter of the cooling pipe holes 8 in the regular triangular arrangement B and the regular square arrangement A are the same, and the ratio of the diameter to the pitch (d / p) is the same.

Therefore, from the above two points, the stress concentration coefficient in the upper tube sheet 41 around the cooling pipe hole 8-1 in the first row where the residual stress F is concentrated is reduced, and the effective residual stress F acting on the upper tube sheet 41 is reduced.
Has a further reduced structure as compared with the case where all the cooling pipe holes 8 and 8-1 have the same arrangement and the regular triangular arrangement B.

A condenser tube sheet according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is an enlarged view of a portion corresponding to a portion near a welding line of an upper tube sheet in a schematic front view of the tube sheet of FIG. 8A illustrating a conventional example, similarly to FIG. 1 showing the first embodiment. FIG.

Also in this embodiment, the arrangement of the cooling pipe holes 8-1 in the first row and the cooling pipe holes 8 in the second row is changed to the cooling pipe holes 8 in the second row and after. A structure that converts to an array type having a smaller stress concentration coefficient than the array type, and further reduces the effective residual stress F acting on the upper tube sheet 41 around the cooling pipe hole 8-1 in the first row where the residual stress is concentrated. It is what it was.

As shown in FIG. 2, specifically, in the case where the arrangement of the cooling pipe holes 8 after the second row of cooling pipe holes 8 is an oblique triangular array C, the cooling pipe holes 8-1 in the first row are replaced with the cooling pipe holes 8-1 in the first row. The arrangement with the cooling pipe holes 8 in the second row was defined as a regular square array A, which was converted into an array form having a smaller stress concentration coefficient than the diagonal triangular array C of the cooling pipe holes 8 after the cooling row 8 in the second row.

On the other hand, as clearly shown in FIG. 2, since the pitch in the square array A is larger than the pitch of the cooling tube holes 8 in the oblique triangular array C in FIG. 2, (d / p) is obliquely triangular. The square array A is smaller than C.

Therefore, the stress concentration coefficient in the upper tube sheet 41 around the cooling pipe hole 8-1 in the first row where the residual stress F is concentrated from the above two points is reduced, and the effective residual stress F acting on the upper tube sheet 41 is reduced.
Has a structure that is further reduced as compared with the case where all the cooling pipe holes 8 and 8-1 have the same arrangement and the oblique triangular arrangement C.

A condenser tube sheet according to a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is an enlarged view of a portion corresponding to a portion near a welding line of an upper tube sheet in a schematic front view of the tube sheet of FIG. 8A illustrating a conventional example, similarly to FIG. 1 showing the first embodiment. FIG.

In this embodiment, as shown in FIG. 3, specifically, in the case where the arrangement of the cooling pipe holes 8 after the second row of cooling pipe holes 8 is an oblique square array D, the first row The arrangement of the cooling pipe holes 8-1 and the cooling pipe holes 8 in the second row is a square array A.
Thus, the cooling pipe holes 8 in the second row and subsequent cooling pipe holes 8 were converted into an array form having a smaller stress concentration coefficient than the oblique square array D.

On the other hand, as clearly shown in FIG. 3, since the pitch in the square array A is larger than the pitch of the cooling pipe holes 8 in the oblique square array D in FIG. 3, (d / p) is The square array A is smaller than that.

Accordingly, the stress concentration coefficient in the upper tube sheet 41 around the cooling pipe hole 8-1 in the first row where the residual stress F is concentrated from the above two points is reduced, and the effective residual stress F acting on the upper tube sheet 41 is reduced.
Has a further reduced structure as compared with the case where all the cooling pipe holes 8 and 8-1 are arranged in the same arrangement and the oblique square arrangement D.

A condenser tube sheet according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is an enlarged view of a portion corresponding to a portion near a welding line of an upper tube sheet in a schematic front view of the tube sheet of FIG. 8A illustrating a conventional example, similarly to FIG. 1 showing the first embodiment. FIG.

In this embodiment, as shown in FIG. 4, specifically, in the case where the arrangement of the cooling pipe holes 8 after the second row of cooling pipe holes 8 is an oblique triangular array C, the first row The arrangement of the cooling pipe holes 8-1 and the second row of cooling pipe holes 8 is a regular triangular array B
Thus, the cooling pipe hole 8 was converted into an array form having a smaller stress concentration coefficient than the oblique triangular array C of the cooling pipe holes 8 after the cooling pipe holes 8 in the second row.

On the other hand, as clearly shown in FIG. 4, since the pitch of the regular triangular array B is larger than the pitch of the cooling pipe holes 8 of the oblique triangular array C in FIG. The regular triangular array B is smaller.

Accordingly, the stress concentration coefficient in the upper tube sheet 41 around the cooling pipe hole 8-1 in the first row where the residual stress F is concentrated from the above two points is reduced, and the effective residual stress F acting on the upper tube sheet 41 is reduced.
Has a structure that is further reduced as compared with the case where all the cooling pipe holes 8 and 8-1 have the same arrangement and the oblique triangular arrangement C.

Further, in the present embodiment, the arrangement of the first and second rows is changed to a regular triangular arrangement B instead of the regular square arrangement A. The arrangement density can be higher than that of the square array A.

A condenser tube sheet according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 5 is an enlarged view of a portion corresponding to a portion near the welding line of the upper tube sheet in the schematic front view of the tube sheet of FIG. 8A illustrating the conventional example, similarly to FIG. 1 showing the first embodiment. FIG.

In this embodiment, as shown in FIG. 5, specifically, in the case where the arrangement of the cooling pipe holes 8 after the second row of cooling pipe holes 8 is an oblique square array D, the first row The arrangement of the cooling pipe holes 8-1 and the cooling pipe holes 8 in the second row is defined as a regular triangular array B, and the stress concentration coefficient is smaller than that of the diagonal square array D of the cooling pipe holes 8 after the cooling pipe holes 8 in the second row. Was converted to a small array.

On the other hand, as clearly shown in FIG. 5, since the pitch in the regular triangular array B is larger than the pitch of the cooling pipe holes 8 in the oblique square array D in FIG. The regular triangular array B is smaller.

Accordingly, from the above two points, the stress concentration coefficient in the upper tube sheet 41 around the cooling pipe hole 8-1 in the first row where the residual stress F is concentrated is reduced, and the effective residual stress F acting on the upper tube sheet 41 is reduced.
Has a structure that is further reduced as compared with the case where all the cooling pipe holes 8 and 8-1 have the same arrangement and the oblique triangular arrangement C.

Further, in the present embodiment, the arrangement of the first and second rows is replaced by the regular triangular arrangement B instead of the regular square arrangement A. The arrangement density can be higher than that of the square array A.

Therefore, as described above, in any of the above-described embodiments, the stress concentration coefficient at the upper tube sheet around the cooling pipe hole 8-1 in the first row with respect to the welding line 43, which has been a problem in the past, is small. Thus, the effective residual stress that acts can be reduced, and the problem of the occurrence of SCC (stress corrosion cracking) is also solved.

In the above-described embodiment, the fact that the pitch of the cooling pipe holes 8-1 in the first row is larger than the pitch of the cooling pipe holes 8 in the second and subsequent rows means that the cooling pipes in the first row are different. It is said that the installation density of 8-1 decreases and the number of installations per area decreases.
When it is assumed that a total of about 10,000 cooling pipes 8 are provided, about 5000 cooling pipes 8 arranged in the first row in the upper tube sheet are provided.
The number 1 is on the order of about 100, and the increase or decrease in the total is less than 1%, which is a range in which the density and performance of the entire cooling pipe 5 do not substantially matter.

Although the embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to the above-described embodiment, and various changes may be made to the specific structure within the scope of the present invention. .

For example, in the above embodiment, the upper tube sheet 41 has been shown and described, but the same applies to the lower tube sheet 42, and the present invention is directed to a condenser having two parts, an upper part and a lower part. The present invention is not limited to this, and can be similarly applied to a welded portion of a condenser tube sheet divided into two or more.

[0049]

(1) According to the first aspect of the invention, the condenser tube sheet is provided with one end of a plurality of cooling pipes in cooling pipe holes provided in a predetermined arrangement on each of a plurality of divided tube sheets. After mounting and fixing the condenser tube plate, the plurality of divided tube sheets are welded and joined to each other to form an integral tube sheet.In the condenser tube sheet, the predetermined arrangement of the cooling pipe holes is from the welding line of the weld joint. Since the arrangement of the first column and the second column is a regular square array, and the arrangement of the second and subsequent columns is configured as any one of a regular triangular arrangement, a diagonal triangular arrangement, and a diagonal square arrangement, Since the stress concentration coefficient in the tube sheet around the cooling pipe hole in the first row where the residual stress due to welding is concentrated is in a square array, any one of the regular triangular array, the oblique triangular array, and the oblique square array is used. The effective residual stress acting is smaller than that of Column, compared positive triangular array, diagonal triangular arrangement, to those with any one sequence of the oblique squares sequence,
The structure is further reduced, and the problem of occurrence of SCC (stress corrosion cracking) is also solved.

(2) According to the invention of claim 2, claim 1
In the condenser tube sheet according to the above, the arrangement of the first row and the second row is a regular triangular arrangement instead of the regular square arrangement, and the arrangement of the second and subsequent rows is the regular triangular arrangement, the oblique Triangular array,
Since any one of the diagonal square arrays is replaced with any one of the diagonal triangular arrangement and the diagonal square arrangement, the first row in which residual stress due to welding is concentrated. The stress concentration coefficient on the tube sheet around the cooling pipe hole is smaller than that of any one of the diagonal triangular arrangement and diagonal square arrangement because of the regular triangular arrangement, and the effective residual stress that acts is all Compared to the case where the cooling pipe holes are arranged in any one of the same arrangement, diagonal triangular arrangement, and diagonal square arrangement, the structure becomes more reduced and the problem of the occurrence of SCC (stress corrosion cracking) is also solved. Also, since the arrangement of the first and second rows is a regular triangular arrangement, the density of the cooling tube holes can be higher than that of a regular square arrangement.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a condenser tube sheet according to a first embodiment of the present invention, showing the vicinity of a welding line of an upper tube sheet in the schematic front view of the tube sheet of FIG. It is an enlarged view of the part corresponding to the part.

FIG. 2 is an explanatory view of a condenser tube sheet according to a second embodiment of the present invention, and is an enlarged view of a portion similar to FIG. 1 in the present embodiment.

FIG. 3 is an explanatory view of a condenser tube sheet according to a third embodiment of the present invention, and is an enlarged view of a portion similar to FIG. 1 in the present embodiment.

FIG. 4 is an explanatory view of a condenser tube sheet according to a fourth embodiment of the present invention, and is an enlarged view of a portion similar to FIG. 1 in the present embodiment.

FIG. 5 is an explanatory view of a condenser tube sheet according to a fifth embodiment of the present invention, and is an enlarged view of a portion similar to FIG. 1 in the present embodiment.

FIG. 6 is an explanatory diagram of an arrangement of holes with respect to directions of applied stress.

FIG. 7 is a sectional elevation view showing a general structure of a conventional condenser.

8 (a) is a schematic front view of a tube plate of a water chamber as viewed in the direction of arrows XX in FIG. 7, and FIG. 8 (b) is a view as viewed in the direction of arrows Y in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Condenser 2 Inlet side water chamber 3 Outlet side water chamber 4 Tube sheet 5 Cooling pipe 6 Low pressure turbine 7 Outlet pipe 8 Cooling pipe hole 8-1 First row cooling pipe hole 41 Upper pipe sheet 42 Lower pipe sheet 43 Welding Line A Regular square array B Regular triangle array C Oblique triangle array D Oblique square array

Claims (2)

[Claims] 1. After a plurality of cooling pipes are fixed at one end to cooling pipe holes provided in a predetermined arrangement on a plurality of divided tubesheets, the plurality of divided tubesheets are welded to each other. In the condenser tube sheet, which is an integral tube sheet, the predetermined arrangement of the cooling pipe holes is 1
A condensate arrangement wherein the array of the second and third columns is a regular square array, and the array of the second and subsequent columns is any one of a regular triangular array, a diagonal triangular array, and a diagonal square array. Instrument panel. 2. The condenser tube sheet according to claim 1,
The arrangement of the first and second columns is a regular triangular arrangement instead of the regular square arrangement, and the arrangement of the second and subsequent columns is any of the regular triangular arrangement, the diagonal triangular arrangement, and the diagonal square arrangement. A condenser tube plate characterized in that, instead of one arrangement, the arrangement is any one of the diagonal triangle arrangement and the diagonal square arrangement.