JPH01266366A - Pressure vessel design method and pressure vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a container made of steel plate into which a high-pressure fluid flows, such as a heat exchanger in a steam power plant, and particularly relates to a container made of a steel plate into which a high-temperature and high-pressure fluid flows. This invention relates to a pressure vessel suitable for use as a pressure vessel.

[Conventional technology]

A pressure vessel made of steel plate is generally constructed by welding, and its outer shape is generally cylindrical, 9-spherical, or a combination thereof, and is provided with a flat portion in the form of a part of these shapes being cut away.

FIG. 3 is an external view showing an example of a pressure vessel having a cylindrical body 2, an end plate 3, and a tube plate 1.

When such a pressure vessel is constructed using conventional technology,
Its cross section is as shown in FIG. The body 2 has an arcuate cross section extending over half the circumference, and the tube plate 1 has a linear cross section.

In the present invention, a linear cross section means a straight line (ie, an elongated rectangle) having a thickness. Similarly, a circular arc shape also means a shape having a thickness.

[Problem to be solved by the invention]

As mentioned above, when a pressure vessel is constructed by joining a steel plate member with an arcuate cross-sectional shape and a steel plate member with a straight cross-sectional shape, concentrated stress occurs near the joint. It is necessary to prevent this from occurring.

For this reason, conventionally, a so-called radius, as shown by an arrow r in FIG. 4, is generally provided. The radius of curvature of this radius is generally about the same as the plate thickness, and at most several times the plate thickness.

With such conventional technology, the pressure resistance of the pressure vessel is limited mainly by the strength of the joints, and in order to increase the pressure resistance, the thickness of the body (the part with an arcuate cross-section) must be increased. Either that or the grade of steel used had to be increased.

Increasing the plate thickness not only increases manufacturing costs, but also requires the support structure of the pressure vessel to be strengthened, creates seismic resistance difficulties, and also causes large thermal stress when the temperature changes. bring about

In addition, increasing the grade of steel plate not only directly increases material costs, but also makes welding more difficult.

Welding defects are likely to occur.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a plate for the arc-shaped portion (portion corresponding to the body) of a pressure vessel whose cross-sectional shape is formed by an arc and a straight line. It is possible to reduce stress at a joint (a joint between a member having an arcuate cross section and a member having a straight cross section) without increasing the thickness or the grade of steel. The present invention aims to provide a pressure vessel design method and a pressure vessel with reduced stress.

[Means to solve the problem]

Regarding the basic principle of the present invention created to achieve the above object, FIG. 1 (A) corresponds to an embodiment of the present invention.
The explanation will be as follows with reference to FIG. 4 and in comparison with the conventional example (FIG. 4).

The radius dimension (arrow r) of the connection part in the conventional example (Fig. 4)
) is approximately the same as the plate thickness dimension t, and the radius R = D of the fuselage 2
/2. Point 0 is the center of the body 2.

In the present invention, the arc 4 of the connecting portion is made larger than conventional technical common sense, and R'>D/2. Accordingly, the center point Q of the radius of curvature is located on the right side of the figure (in the direction away from the tube plate 1) than the center point of the body 2.

In this case, if the connecting arc 4 is made into a single circular arc with the radius R' as a constant, the intersection of the connecting arc 4 and the circumferential arc 5 has an angle (
A discontinuous point) is formed, and an angle is formed at the intersection of the connecting arc 4 and the inner straight line 6.

Therefore, in the present invention, the R' dimension is made a variable or the center point Q is made a non-fixed point, the connecting arcs are made into multiple arcs, and the inner circumferential arc 5 and the inner straight line 6 are connected by multiple arcs.

[Effect]

According to the above configuration, the inner circumferential arc 5 of the body 2 and the inner plane 6 of the tube plate 1 are smoothly connected by the joining arc 4 having an extremely large radius of curvature.

An extremely large radius of curvature means that it is much larger than the plate thickness dimension t, and further larger than the radius R of the inner circumferential arc of the body 2.

Therefore, there is no risk of stress concentration occurring in this connection, and the pressure resistance can be increased without requiring an increase in the thickness of the body or the grade of steel plate.

〔Example〕

FIG. 1(A) is a sectional view showing an embodiment of a pressure vessel according to the present invention.

1 is a tube plate made of steel plate, and the inside thereof forms an inner plane 6.

2 is a cylindrical body. Although the description will be omitted with separate drawings, the present invention can also be applied to a spherical body having a similar cross-sectional shape.

5 is an inner circumferential arc in the cross-sectional shape of the fuselage 2.

When viewing FIG. 1(A) three-dimensionally, the inner straight line 6 is an inner plane. Moreover, if FIG. 1(A) is viewed three-dimensionally, the inner circumferential arc 5 is a cylindrical inner circumferential surface.

Hereinafter, in this section, description will be made using terms when FIG. 1(A) is viewed from above.

Point 0 is the center point of the body 2. The radius R of the inner circumferential arc 5
=D/2. The illustrated curve 4 connects the inner circumferential arc 5 and the straight line of the inner plane 6.

FIG. 1(B) is an explanatory diagram of the connecting arc, in which the inner straight line 6 and the inner circumferential arc 5 shown in FIG. 1(A) are shown by solid lines.

Point O is the center point of the inner circumferential arc 5, and point a is the center point of the inner circumferential arc fi5.
and the inner straight line 6.

Select a point Q that is farther from the inner straight line 6 than point O, and draw an arc Ω with a radius R' such that R'>R=D/2.The point Q is the intersection with the inner straight line 6.

Point C is the intersection with the inner circumferential arc 5.

If we find the above arc bc, we can connect the inner circumferential arc 5 and the inner straight line 6 with an arc with a radius larger than R, but
A corner (discontinuous point) is created near the single point C. To correct this, take the following design steps.

One point S on the inner straight line 6 is taken on the opposite side to point a, and a perpendicular line is drawn on the inner surface 1Ii6.The point S is the intersection of the above perpendicular line and the radius Qq.

A dotted circular arc is drawn with the above point S as the center and radius sh as the radius.This circular arc q is in contact with the inner straight line 6 and smoothly connected.

The discontinuous point at point C is also corrected in the same way as above so that it connects smoothly.

In this way, the inner circumferential arc 5 and the inner straight line 6 are
Connect smoothly with multiple arcs with a radius of curvature larger than /2.

In the present invention, multiple arcs refer to (a) three or more arcs touching each other, and (b) envelopes of three or more arcs. However, the circular arc in the present invention includes a circular arc (that is, a straight line) with an infinite radius.

FIG. 1(A) is a sectional view showing an embodiment of a pressure vessel in which a connecting arc 4 is constructed according to the above-described design procedure.

FIG. 2 is a bar graph showing the peak stress ratio when internal pressure is applied to each of the conventional pressure vessel (FIG. 4) and the pressure vessel of the present example (FIG. 1 (A)). .

When the stress of the conventional example (i) is 1, the stress (3X) of this example is about 0.7.

For comparison, the body 2 of the conventional pressure vessel (Fig. 4)
The stress when the wall thickness dimension t of is increased by 1.4 times is shown in (in). Its value is approximately 0.83.

In this example, by making the arc of the connection part a multiple arc with a large diameter, it was possible to significantly reduce the peak stress compared to an increase in the body thickness.

〔Effect of the invention〕

According to the pressure vessel of the present invention, peak stress can be significantly reduced without increasing the thickness of the body or increasing the grade of steel plate.

Moreover, according to the design method of the present invention, the pressure vessel according to the above-mentioned invention can be reliably and easily configured to exhibit its effects.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the pressure vessel according to the present invention, and shows the first embodiment of the pressure vessel according to the present invention.
FIG. 1(A) is a sectional view, and FIG. 1(B) is an explanatory diagram of the design procedure. FIG. 2 is a chart showing the effects of the above embodiment. 3 and 4 show a conventional pressure vessel, with FIG. 3 being an external perspective view and FIG. 4 being a sectional view. 1... A tube sheet as a member having a linear cross-sectional shape, 2
...A fuselage as a member having an arcuate cross-sectional shape, 3.
... End plate, 4... Connection arc, 5... Inner circumference arc, 6.
・Inner straight line. Representative Patent Attorney Tadashi Akimoto Figure 1 (B”) #72 Figure 3rd 4Z

Claims (1)

[Claims] 1. A method for designing the cross-sectional shape of the inner peripheral surface of a portion where the arc and the secant line intersect in a pressure vessel made of a steel plate, the cross-sectional shape of which has one circular arc and one secant line, The radius of the circular arc is set to D/2, the center of the circular arc is set to a point O, and the center is located at a location farther from the secant line than the above point O, and the above-mentioned multiple circular arc is larger than the radius D/2. A pressure vessel design method characterized by smoothly connecting a circular arc with a radius of D/2 and a secant line. 2. A steel plate member having an arcuate cross-sectional shape of half a circumference or more;
In a pressure vessel in which a steel plate member having a linear cross-sectional shape and a steel plate member are fixed to each other, the inner peripheral surfaces of both members have a radius of curvature larger than the radius of the circular arc and are eccentric with respect to the circular arc. A pressure vessel characterized by smooth connections with multiple arcs. 3. The pressure vessel according to claim 2, wherein the member having an arcuate cross-sectional shape is a cylindrical member. 4. The pressure vessel according to claim 2, wherein the member having an arcuate cross-sectional shape is a spherical member. 5. The pressure vessel according to claim 3 or 4, wherein the member having a linear cross-sectional shape is a tube plate.