JP2002116279A - High-temperature vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the strength soundness of a high-temperature vessel by reducing thermal stresses generated to the root of a skirt in the high- temperature vessel. SOLUTION: The high-temperature vessel has a vessel 1a for storing a high temperature fluid, and the fan-shaped cylindrical skirt 1b, having one end connected to an outer periphery of the container 1a and the other end part fixed to a base 2. An acetylene soot radiation coating 9 is formed on an outer peripheral face 10 of the container and an inner peripheral face 11 of the skirt opposite to each other, in the vicinity of the skirt root 12 where the skirt 1b is connected to the container 1a. The radiation coating 9 has emissivity larger than emissivities of these faces 10 and 11. A heat transfer by radiation is increased between the faces 10 and 11, so that the temperature difference between the container 1a and the skirt 1b is reduced quickly. The thermal stresses of the skirt root are thus reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature vessel for storing a high-temperature fluid, and more particularly to a method for reducing a temperature difference at a root portion between a pressure vessel and a skirt attached to an outer periphery of the pressure vessel, such as a reactor pressure vessel. The present invention also relates to a high-temperature container suitable for reducing thermal stress generated therein.

[0002]

2. Description of the Related Art An example of a reactor pressure vessel will be described as a conventional high-temperature vessel. As shown in FIG. 1, a typical reactor pressure vessel 1 has a flared skirt 1b attached to the outer periphery of a body of a vessel 1a for storing a high-temperature fluid, and a skirt flange 1c at the tip of the skirt 1b is used as a base. It is configured to be fixed. Most of the skirt flange is kept warm by the heat retaining material 7 as shown in FIG.
The purpose of this heat retention is to prevent heat radiation from the skirt 1b, reduce the temperature difference between the container 1a and the skirt 1b, and reduce the thermal stress at the root of the skirt.

In the conventional structure, when the pressure vessel is heated,
As for the temperature rise of the skirt 1b due to the temperature rise of the container 1a, heat conduction from the skirt base 12 is dominant. At this time, the outer peripheral surface 10 of the container 1a and the skirt
The temperature of the skirt 1b also rises due to face-to-face radiation with the inner peripheral surface 11 of 1b, but the effect is smaller than the above-mentioned heat conduction,
When the temperature rises, a temperature difference occurs between the container 1a and the skirt 1b. As a result, the skirt root 12 mainly restrains the thermal expansion of the reactor pressure vessel 1 in the radial direction, and when the temperature rises, the skirt 1b causes a large deformation of the skirt root 12 as shown by a broken line in FIG. Large thermal stress occurs.

Another example of a reactor pressure vessel is shown in FIG. This reactor pressure vessel 1 is different from that shown in FIG. 1 only in that the shape of the skirt b is substantially cylindrical and that the mounting position is below the vessel 1a. The same applies to the operation and deformation of the container during temperature rise.

FIG. 9 shows a conventional technique disclosed in
In the technique disclosed in Japanese Patent No. 54595, a metal fiber 26 having high thermal conductivity is provided in a space between a high-temperature container 21 having a nozzle 23 at the top and containing a high-temperature fluid 24 therein and a support skirt 1b. After filling, the heat of the container 1a is to be transferred to the low temperature side skirt 1b by the heat conduction through the metal fibers 26. However, in this method, it is assumed that the metal fibers 26 are used in the form of a mesh, and it is troublesome and costly to perform the construction. However, even if metal fibers having good thermal conductivity are used, there is a problem that the heat transfer effect is reduced.

[0006] FIG.
In the technique disclosed in Japanese Patent Application No. 59-9593, the skirt 1b is thermally expanded by heating and raising the temperature of the skirt 1b using the heater 32. A thermocouple 33 for measuring a heating temperature and a temperature controller 34 are provided. However, this method is not preferable because equipment and its control are complicated.

[0007]

In the above-mentioned prior art nuclear pressure vessel, the temperature rise of the skirt 1b is caused by the rise of the skirt root 12b.
Since heat conduction from the skirt is dominant, when the temperature of the reactor pressure vessel 1 rises, the temperature rise on the skirt 1b side is slow, and there is a problem that a large thermal stress is generated at the root of the skirt. Further, even if an attempt is made to solve the problem of the thermal stress generated at the root of the skirt by using the techniques disclosed in the above publications, there is a point that it is not preferable in terms of workability and reliability.

An object of the present invention is to reduce the temperature difference between a container and a skirt in a high-temperature container by improving not only the heat transfer from the container to the skirt but also the heat transfer due to the face-to-face radiation between the two. Another object of the present invention is to reduce the thermal stress generated at the root of the skirt to improve the strength and soundness of the high-temperature container.

[0009]

In order to achieve the above object, a high-temperature container according to the present invention comprises: a container for storing a high-temperature fluid;
In a high-temperature container comprising a cylindrical skirt having one end connected to the outer periphery of the body of the container and the other end fixed to a foundation on which the container is installed, the outer peripheral surface of the container near the root of the skirt to which the skirt is connected to the outer periphery of the container; A coating having a higher emissivity than the outer peripheral surface of the container and the inner peripheral surface of the skirt is formed on the inner peripheral surface of the skirt facing the outer peripheral surface. The coating is preferably made of acetylene soot.

[0010] In the high-temperature container configured as described above, heat transfer from the high-temperature container to the low-temperature skirt is as follows.
Unlike conventional heat conduction, heat conduction is performed by radiation between the coating on the outer peripheral surface of the container and the coating on the inner peripheral surface of the skirt that oppose each other. The heat transfers to a wide area of the skirt. Therefore, when the temperature of the high temperature container is raised, the deformation of the skirt caused by the thermal expansion of the high temperature container is absorbed in a wide range of the skirt, and the thermal stress generated at the root of the skirt is reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A high-temperature container according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a view showing the structure of a reactor pressure vessel as a high-temperature vessel, FIG. 2 is a view showing a skirt connected to the vessel in a detailed view of part A of FIG. 1, and FIG. FIG. As shown in FIG. 1, the reactor pressure vessel 1 generally includes a cylindrical vessel 1a for storing a high-temperature fluid, a skirt 1b attached to the outer periphery of the body of the vessel 1a, and a skirt flange 1c at the tip of the skirt 1b. It is composed of skirt
1b is a conical cylinder having one end connected on the circumference of the body 1a at an intermediate position in the axis (up and down) direction of the body of the container 1a and diverging downward, and an annular skirt flange 1c is attached to the other end. ing. The skirt flange 1c is provided on a base 2 provided on a shield 8 surrounding the reactor pressure vessel 1 through a base plate 3,
It is fixed with nuts 4, bolts 5, and washers 6. Further, both the inner and outer surfaces of the skirt 1b are covered with the heat insulating material 7, thereby reducing heat radiation from the skirt 1b.

As a feature of the present invention, as shown in FIG. 2, near the root of the skirt where the skirt 1b is connected to the body of the container 1a, the outer surface 10 of the body of the container 1a and the inner surface of the skirt 1b are connected.
The radiation coating 9 is formed by performing a surface treatment to adhere acetylene soot to 11.

The operation of the reactor pressure vessel 1 will be described.
When the reactor pressure vessel 1 shifts from the stopped state to the operating state, the reactor pressure vessel 1 thermally expands and expands in the radial and axial directions as the temperature of the internal fluid increases. Skirt 1b
Because the other end is fixed to the foundation 2, the reactor pressure vessel 1
Radial expansion causes the skirt 1b to deform, generating a large thermal stress at the root of the skirt. The heat of the fluid inside the reactor pressure vessel 1 is transferred from the body of the vessel 1a to the skirt 1b through the root of the skirt by heat conduction, and the radiation coating 9 on the outer surface of the body of the vessel 1a is radiated from the radiation coating 9 on the inner surface of the skirt 1b facing the same. The film moves to the skirt 1b via the radiation coating 9. By providing the radiation coating 9 made of soot of acetylene in this way, the amount of heat transmitted from the container 1a to the skirt 1b by radiation can be increased as compared with the conventional case, so that the heat diffusion in the skirt 1b becomes faster, The thermal expansion of the pressure vessel 1 is absorbed by a wide range of deformation of the skirt 1b, so that deformation of the root of the skirt and thermal stress are reduced. In FIG. 3, the solid line shows the shape of the reactor pressure vessel with the radiation coating 9 formed at the root of the skirt when the reactor pressure vessel is installed or stopped, and the broken line shows the deformed state when the temperature is raised. The thermal deformation of the reactor pressure vessel 1 according to the present invention shown in FIG. 3 is compared with the thermal deformation of the conventional reactor pressure vessel without a radiation coating (FIG. 7).
In the reactor pressure vessel of the present invention, the skirt is
It can be seen that the area to be deformed in 1b is expanded and the entire area is deformed. Thereby, the thermal stress at the root of the skirt is reduced, and the soundness of the skirt 1b can be improved. In addition,
The material of the radiation coating is not limited to acetylene soot, as long as the material has a higher emissivity than the outer peripheral surface of the container and the inner peripheral surface of the skirt.
You can use it. Next, Embodiment 2 of the present invention
The high-temperature container which will be described below will be described with reference to FIGS. FIG. 4 is a view showing the structure of another reactor pressure vessel as a high temperature vessel, FIG. 5 is a view showing a skirt connected to the vessel in a detailed view of part A in FIG. 4, and FIG. 6 is a view of the vessel and the skirt shown in FIG. FIG. Another reactor vessel 1 is different from the type shown in FIG. 1 only in the shape and mounting position of the skirt 1b.
Others can be said to be the same. That is, this reactor pressure vessel 1
As shown in FIG. 5, generally comprises a cylindrical container 1a for storing a high-temperature fluid, and a cylindrical skirt 1b attached to the outer periphery of the lower part of the body of the container 1a. Skirt 1b
Has one end connected to the circumference of the trunk, and an annular skirt flange 1c is attached to the other end. Skirt flange
1c is fixed to the foundation 2 on which the reactor pressure vessel is installed. The inner and outer surfaces of the skirt 1b are covered with a heat insulating material 7. The radiation coating 9 which is a feature of the present invention is shown in FIG.
As shown in (1), it is formed from the outer peripheral surface of the body of the container 1a to the inner peripheral surface of the skirt 1b near the root of the skirt where the skirt 1b is joined to the body of the container 1a.

The operation of the reactor vessel of the second embodiment is the same as that of the first embodiment, and the modification of the reactor vessel of the second embodiment shown by a chain line in FIG. 6 is different from that of the conventional reactor shown in FIG. From this, it can be seen that the skirt 1b is entirely deformed. Thus, the thermal stress at the root of the skirt is reduced,
The soundness of the skirt can be improved.

Here, the amount of heat transfer Q by radiation will be considered. When the heat transfer amount Q by radiation to a temperature of two surfaces between _{T 1} and _{T 2,} respectively, which are opposite to each other, is a constant × determined by Q = shape ^_(T 1 4 _-T ^{2 4)} × emissivity (1). When T ₁ As is apparent from equation (1) increases, decreases the effect of T ₂ to Q, effect on Q becomes T ₁ is dominant. Since Q at this time is approximately proportional to the fourth power of T ₁ , the effect of the present invention becomes more remarkable as T ₁ (the temperature of the high-temperature vessel) is higher.

[0016] The temperature term (T₁ ⁴-T
₂ ⁴). In the case of light water reactors, the atomic
Furnace pressure vessel temperature T₁Is about 550K, which is
If T₁Is about 770K. At the time of each furnace shutdown
Temperature T at root of supporting skirt ₂To 300K (normal temperature)
And (770⁴−300⁴) / (550⁴−300⁴) Is about 4
Become. That is, considering only the temperature, the fast breeder reactor is a light water reactor.
Transfer radiant heat four times larger than that of the container to the skirt
become.

Consider the emissivity term in equation (1). In each of the above embodiments, the radiation coating formed by surface-treating the root portion of the skirt is made of acetylene soot. In the case of a light water reactor pressure vessel, the high temperature vessel and supporting skirt are made of low alloy steel, etc.
The steel surface becomes an oxidized surface. In the case of a fast breeder reactor or the like, since the high-temperature vessel and the supporting skirt are made of stainless steel, their surfaces are hardly oxidized (rusted), and are equivalent to a polished surface of steel in terms of emissivity. The emissivity of the acetylene soot coating, the oxidized surface of the steel and the polished surface of the steel are as follows. Emissivity of the acetylene soot coating: 0.99 (260 ° C) Emissivity of the oxidized steel surface: 0.79 (260 E) Emissivity of polished steel surface: 0.10 (260 ° C).

When the reactor is made of low-alloy steel or the like like a reactor pressure vessel of a light water reactor and is oxidized, the emissivity becomes 0.99 / 0.79 times by applying a soot coating of acetylene.
Heat transfer by radiation is expected to improve by about 25%. On the other hand, when the high-temperature vessel and the supporting skirt are made of stainless steel, such as a fast breeder reactor, and are hardly oxidized (rusted) and have low emissivity, the emissivity is reduced by applying an acetylene soot coating.
It becomes 0.99 / 0.10 times, and the heat transfer by radiation improves almost 10 times.

In the case of a metal, the thermal conductivity is greatly affected by purity, and the thermal conductivity of a metal or alloy containing impurities is considerably smaller than that of a pure metal as described below. For this reason, when the high-temperature container is made of stainless steel and the acetylene soot coating is applied, the ratio of heat transfer by radiation and heat conduction by heat is determined by applying the acetylene soot coating with the high-temperature container made of low alloy steel. It is almost four times the case.

Thermal conductivity of low alloy: 69.8 (W / (m / k): 300 ° C.) Thermal conductivity of stainless steel: 17.4 (W / (m / k): 300 ° C.) When the soot coating of acetylene is applied to the furnace, it is approximately 4 times (10 times / 1.25 times) x 4 times = 128 times more effective than when the coating is applied to a light water reactor.

[0021]

According to the present invention, in the high-temperature container, the thermal stress generated at the root portion of the skirt where the skirt is joined to the container is lessened than that of the conventional structure, so that the strength and soundness of the high-temperature container can be improved. .

[Brief description of the drawings]

FIG. 1 is an overall structural diagram illustrating an example of a reactor pressure vessel according to a first embodiment of the present invention.

FIG. 2 is a detailed view of a portion A of FIG. 1, showing a structure of a skirt portion coupled to a container.

FIG. 3 is a view for explaining deformation of the container and the skirt shown in FIG. 2 when the temperature is raised.

FIG. 4 is an overall configuration diagram showing another example of a reactor pressure vessel according to Embodiment 2 of the present invention.

5 is a view showing a structure of a skirt portion coupled to the container in a detailed sectional view of a portion C in FIG. 4;

FIG. 6 is a view for explaining deformation of the container and the skirt shown in FIG. 5 when the temperature is raised.

FIG. 7 is a diagram illustrating thermal deformation of a vessel and a skirt in an example of a conventional reactor pressure vessel.

FIG. 8 is a view for explaining thermal deformation of a vessel and a skirt in another example of a conventional reactor pressure vessel.

FIG. 9 is an overall and detailed view showing a stress reduction method disclosed in Japanese Patent Application Laid-Open No. 58-54595 as a conventional technique.

FIG. 10 is an overall configuration diagram showing a stress reduction method disclosed in Japanese Patent Application Laid-Open No. 59-9593 as a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor pressure vessel 1a Vessel 1b Skirt 1c Skirt flange 2 Foundation 3 Base plate 7 Heat insulator 8 Shield 9 Radiation coating 10 Vessel outer surface 11 Support skirt inner surface 12 Support skirt root

Claims (2)

[Claims] 1. A high-temperature container comprising: a container for storing a high-temperature fluid; and a cylindrical skirt having one end connected to the outer periphery of a body of the container and the other end fixed to a foundation on which the container is installed. Near the root of the skirt where the skirt is connected to the outer periphery of the container, the outer peripheral surface of the container and the inner peripheral surface of the skirt facing the outer peripheral surface have a higher emissivity than the outer peripheral surface and the inner peripheral surface. A high-temperature container having a coating formed thereon. 2. The high-temperature container according to claim 1, wherein the coating is made of acetylene soot.