JPS61153098A - Cryogenic double shell tank - Google Patents

Abstract

PURPOSE:To enable a tank to follow thermal expansion and thermal shrinkage, by method wherein a skirt is divided between an inner and an outer tank, a shear plate is located to the upper skirt, and a heat member is increased in pressure resistance and shearing resistant force. CONSTITUTION:Inner and outer tanks 1 and 2 are formed as a spherical tank, and the inner tank 1 is supported to a foundation 3 through a cylindrical skirt 7 extended downward from a portion in the vicinity of its equator through the outer tank 2. The skirt 7 is horizontally divided between the inner and outer tanks 1 and 2, and is formed with upper and lower skirts 8 and 9. Plural heat insulating members 12 are located circumferentially at equal intervals between upper and lower ring flanges 10 and 11, a striplike shear plate is secured to the under surface of the upper ring flange 10 by welding so that upper sides, parallel to each other, of each of of the heat insulating members 12 are slidably nipped.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a cryogenic double-shell tank designed to prevent heat input from the outside as much as possible.

Conventional technology As a container for storing cryogenic liquids such as liquid nitrogen, liquid oxygen, and liquid hydrogen, there is a double-shell pressure vessel type tank that has an inner tank and an outer tank, and the space between them is used as a heat insulating layer. Generally adopted. In this type of tank, the outer tank is in contact with the atmosphere, and the inner tank is cooled by contacting cryogenic liquid when it is a trench tank.When the tank is empty, the temperature rises and the inner tank expands and contracts depending on the temperature, so the inner tank can be removed from the tank. It is necessary to devise a method for supporting the tank.

Conventional cryogenic tanks of this type have a storage capacity of, for example, 1O~
100rr? Because of its relatively small size, the structure of the tank is as shown in Figures 6 and 7, with the inner tank 1 being diagonally installed on the inner surface of the outer tank 42 supported by pillars 4 erected on the foundation 3. A so-called suspension rod system in which the vehicle is supported via a large number of suspension rods 5 has been widely adopted. The space 6 between the inner tank 1 and the outer tank 2 is made of a vacuum or a normal pearlite heat insulating layer. Regarding this method,
The behavior during an earthquake is unknown, and it is extremely difficult to make all suspension rods have the same tension, so earthquake resistance and
Skirt support is lacking in workability and reliability, and as tanks become larger, the inner tank 1 is supported by a cylindrical skirt 7 that penetrates the outer tank 2, as shown in FIGS. 8 and 9. Tanks began to be built gradually.

Problems to be Solved by the Invention Although this system is advantageous in terms of strength as a large-scale pressure vessel type cryogenic tank, since the cross-sectional area of the skirt portion 7゛ is large, heat conduction through the skirt portion causes the inner tank to The biggest drawback is that there is a large amount of heat intrusion into the interior. Therefore, even if the heat insulating performance of the heat insulating layer 6 is improved by, for example, cutting, super insulation, etc., it is difficult to reduce the amount of heat intrusion from the skirt part, and as the heat input in other parts decreases, the skirt The ratio of heat input from the area increases. Therefore, if reliquefaction equipment is required, or if there is no reliquefaction equipment and if more boil-off gas is generated per unit time than the amount used, the excess boil-off gas must be disposed of, so the stored liquid is It is extremely uneconomical to use an expensive product like liquid hydrogen.

, Means for Solving the Problems This invention solves the above-mentioned problems of the conventional skirt-supported double-shell cryogenic tank and provides a cryogenic double-shell tank that can minimize the amount of heat input from the outside. The purpose is to provide.

In order to achieve the above-mentioned purpose, the cryogenic double shell tank according to the present invention consists of an upper skirt whose upper end is fixed to the inner tank and an upper ring flange at the lower end, the lower end is a foundation, and the middle part is attached to the outer tank. and a lower skirt having a lower ring flange opposite to the upper ring flange at the upper end, and a lower skirt on the lower surface of the upper ring flange on both sides of each of a plurality of straight lines extending radially from the vertical center line of the inner tank. Two strip-shaped shear plates are fixed in parallel to this,
Between the upper and lower ring flanges, there is a heat insulating member having a cross-sectional area that can withstand a predetermined shearing force in the circumferential direction and a predetermined compressive force in the circumferential and vertical directions. It is characterized in that it is slidably held between a pair of shear plates, the upper surface is slidable on the lower surface of the upper ring flange, and the lower surface is fixed on the upper surface of the lower flange.

Effect With the above configuration, when the inner tank expands and contracts due to temperature changes, the upper skirt fixed to the inner tank expands and contracts following the inner tank, and is displaced relative to the lower skirt that is integrally fixed to the outer tank. However, since the shutter plate fixed to the upper skirt can slide in several directions relative to the heat insulating member fixed to the lower skirt, the inner tank remains fixed in position on the vertical center line and can rotate. It can be easily displaced without causing any large thermal stress on the inner and outer tanks or the skirt. Further, since the upper skirt and the lower skirt are connected through a heat insulating material, the amount of heat input from the outside through the skirt 3 is extremely small. In addition, the heat insulating member is designed to withstand not only compressive force but also a predetermined shear force in the circumferential direction, so it is possible to prevent displacement and rotation in the horizontal plane with just a simple shear plate. , the configuration becomes extremely simple.

Embodiment FIG. 1 is a diagram showing an embodiment of the present invention, in which the inner tank lx and the outer tank 2 are constructed as concentric spherical tanks, and the inner tank l extends downward from near its equator and penetrates through the outer tank 2. It is supported on the foundation 3 via a cylindrical skirt 7.

The skirt 7 is horizontally divided between the inner tank 1 and the outer tank 2, and is composed of an upper skirt 8 and a lower skirt 9. The upper skirt 8 has an upper end fixed to the inner tank 7, and an upper ring flange 10 fixed to the lower end.

The lower end of the lower skirt 9 is fixed to the foundation, and the middle part is attached to the outer tank 2.
A lower ring flange 11 facing the upper ring flange 10 is fixed at the upper end.

As shown in FIG. 3, a plurality of heat insulating members 12 are provided at equal intervals in the circumferential direction between the upper and lower ring flanges 10.11. Both circumferential directions of the skirt of the heat insulating member 12 (tl
! Ii is made parallel to a radial straight line passing through the center of the heat insulating member 12 from the center of the circle of the skirt. On the lower surface of the upper ring flange 1o, as shown in FIG.
An IJ knob-shaped shear plate is fixed by welding so as to slidably clamp the upper portions of both mutually parallel sides of the shear plate.

A similar shear plate 13 is fixed to the upper surface of the lower ring flange 11 at the center of the circumferential width of the heat insulating member 120, and a fitting groove 14 is provided in the heat insulating member 12 correspondingly. The lower surface of the upper ring flange 10 of the heat insulating member 12 and the contact surface with the shear plate 13 attached thereto are coated or pasted with a low-friction material to facilitate sliding.

It is. The lower surface of the heat insulating member 12 is the lower ring flange 11
The heat insulating member 12 is fixed to the lower ring flange 11 together with the action of the shear plate 13.

Now, the heat insulating member 12 is made of FR with a large proportion of glass fiber.
Made of P, it has large compressive strength and circumferential shear strength? The horizontal cross-sectional area is such that it can sufficiently withstand the compressive force due to the load of the inner tank and the liquid inside it, and the shearing force acting through the shear plate 13 provided on the upper ring flange 10 due to horizontal force due to earthquakes, etc. 0 set to
Furthermore, 1FPR has low thermal conductivity and excellent heat insulation properties.

Since this device is constructed as described above, the heat input from the outside through the skirt portion 7 during normal operation is limited to the upper and lower skirts 8.9.
The amount of heat input into the inner tank 1 is extremely small because it is blocked by the heat insulating member 12 interposed between the two. Moreover, the compressive strength and horizontal cross-sectional area of the heat insulating member 12 sufficiently support the weight of the inner tank and the liquid stored therein. In addition, against thermal expansion and thermal contraction due to thermal changes in the inner tank l, the center position is maintained and the rotation You can follow it without having to do anything. Furthermore, during an earthquake, for example, the shear plate 13 and the heat insulating member 12 in the direction parallel to the horizontal seismic force QE shown in FIG. is the seismic force Qr depending on the angle with respect to the direction of the seismic force.

resists the component of shear force in the direction perpendicular to , and prevents movement of the inner tank in the horizontal plane.

Falling down (surfacing) during an earthquake? To prevent this, the inside [1] of the connection part 15 between the upper skirt 8 and the lower skirt 9 shown in FIG.
Distance h downward from the center of r: Should be selected so as to satisfy the following formula: h (where t is the diameter of the skirt) The reason for this is explained below.

During an earthquake, the horizontal seismic force QE acting on the center of gravity of the inner tank is QE =
kW Here, W is the overturning moment around the weight point 15 of the inner tank and the liquid inside it) MT is MT = QEX h =
kWh - 10,000, stability moment MS around point 15 due to weight W
is Ms = W This is an example in which the skirt 7 has an upper end fixed to the connection part between the lower end plate of the inner tank 1 and the cylindrical body, and the upper skirt 8 and the lower end are fixed between the inner tank 1 and the outer tank 2. The insulating member 12 between these parts and its support structure are the same as in the previous embodiment. A fall prevention material 16 made of a heat insulating material having pressure resistance is fixed to a part of either the inner tank l or the outer tank 42 at four locations in the circumferential direction of the upper part of the cylindrical body between it and the outer tank 2, There is an appropriate amount of time between you and the other person.
It is constructed by providing a slider and installing it in a slidable manner.

During an earthquake, the shear plate 13 of the upper skirt 8 and the insulation member 1
2 and try to float by sliding each other, but the fall prevention material 1
Any of 6! Falling over is prevented by eliminating the gap between the inner and outer tubs and making contact with each other. Under normal conditions, even if the inner tank thermally contracts or expands, it can be easily displaced relative to the outer tank.

Conventionally, as a measure to prevent overturning and floating during earthquakes, many anchor bolt heads were engaged with elongated holes in members fixed to the inner tank. However, in the above two embodiments, there is no risk of restraining the mutual displacement of the upper ring flange and the heat insulating member under normal conditions, and moreover, in the event of an earthquake, the Falls are prevented.

In the above embodiment, the fixation between the heat insulating member 12 and the lower ring flange 11 is achieved by providing one shear plate at the center of the width in the circumferential direction and fitting it into the groove 14 provided on the lower surface of the heat insulating member 1°2. Although this is done by bonding the lower surface and the lower ring flange 11, similar to the shear plate of the upper ring flange 10, shear plates may be provided on both sides of the heat insulating member 12 and sandwiched therebetween.

Effects As described above, in the cryogenic double shell tank of the present invention, the skirt 2 is divided between the inner tank and the outer tank, and the shear plate 2 is provided on the upper skirt, so that the heat insulating member has not only pressure resistance but also shear resistance. By having the same structure, thermal expansion and contraction can be followed with a simple configuration, horizontal movement and floating during an earthquake can be prevented, and the amount of heat input from the outside can be reduced.

[Brief explanation of the drawing]

Is Figure 1 the invention? A cross-sectional view showing the overall configuration of an embodiment applied to a spherical double-shell tank, FIG. 2 is a cross-sectional view showing an enlarged part of the skirt portion, and FIG. 3 is a horizontal cross-sectional view of the upper and lower skirt connection portions. FIG. 4 is a perspective view showing a part of the upper and lower skirt connections in detail, FIG. 5 is a sectional view showing another embodiment of the present invention, and FIGS. 6 to 9 are respectively conventional cryogenic double shells. FIG. 2 is a sectional view showing a schematic configuration of a tank. 1...Inner tank, 2...Outer tank, 3...Foundation, 6...
Heat insulation layer, 7... Skirt, 8... Upper skirt, 9.
...Lower skirt, 10...Upper ring flange, 11.
...Lower ring flange, 12...Insulation member, 13...
・Shear plate, 16... Fall prevention material, Yasukifu No. 61'-! :1 Figure 8 7-I5ζ1 91st Go! 1

Claims (3)

[Claims] (1) It has an inner tank for storing a cryogenic liquid, and an outer tank surrounding it with a predetermined insulating space interval, and the inner tank is connected to the outer tank and the foundation through a cylindrical skirt concentric with the inner tank. In a cryogenic double shell tank supported on the inner tank, the above skirt has an upper end fixed to the inner tank, an upper skirt with an upper ring flange at the lower end, the lower end is fixed to the foundation, the middle part is fixed to the outer tank, and the upper end and a lower skirt having a lower ring flange facing the upper ring flange, and on the lower surface of the upper ring flange, there are two parallel lines on both sides of each of a plurality of straight lines extending radially from the vertical center line of the inner tank. A book strip-shaped shear plate is fixedly installed, and a heat insulating member having a cross-sectional area that can withstand a predetermined shearing force in the circumferential direction and a predetermined compressive force in the vertical and circumferential directions is installed between the upper and lower ring flanges. , its upper both sides are slidably sandwiched between the pair of mutually parallel shear plates, the upper surface is slidable on the lower surface of the upper ring flange, and the lower surface is fixed to the upper surface of the lower flange. A cryogenic double shell tank featuring: (2) The inner tank and the outer tank are each concentric spherical tanks, the skirt supports the inner tank near the equator of the inner tank, and the tank is located at the joint between the upper skirt and the lower skirt. Claim 1, characterized in that the distance h downward from the center is smaller than l/2k, where l is the diameter of the skirt and is the seismic coefficient for the seismic intensity of the earthquake that the tank should withstand. The cryogenic double shell tank described. (3) The above-mentioned inner tank and outer tank are each concentric cylindrical tanks, and the required pressure resistance and heat insulation are installed at appropriate number of locations in the circumferential direction between the upper part of the side surface of the inner tank and the outer tank. The cryogenic temperature chamber according to claim 1, characterized in that the overturn prevention member having the above-mentioned fall prevention member is fixed to only one of the inner tank and the outer tank, and the other is slidably installed with a gap provided. Heavy shell tank.