JPH0752870A - Hull protection device in liqueified gas carrier - Google Patents

Abstract

PURPOSE:To provide the hull protection device which can effectively prevent leaking liquid from a storage tank from being reached a hull. CONSTITUTION:The overall surface of a tank main body 4 is covered by a cold insulation panel 5 while being watertight, moreover, drain ports 10 draining leaking liquid out, which leaks in the inside of the cold insulation panel 5 out of the tank main body 4, are provided at four corner sections in the bottom surface of its storage tank 1, and trays 11 for receiving the leaking liquid are disposed below the draining ports. If there exists any recessed section in the bottom surface of the tank, a swelled section covering the recessed section is formed in the cold insulation panel, and a drain port and a tray are provided for the swelled section too. It is desirable that each drain port is provided with a drain valve 12 which is normally closed, but is opened only when leaking fluid is reached the drain port.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a liquefied gas carrier such as an LNG carrier, and in the event that liquid leaks from a liquefied gas storage tank, the leaked liquid is prevented from reaching the hull. The present invention relates to a hull protection device.

[0002]

2. Description of the Related Art As an LNG carrier for transporting liquefied natural gas, as shown in FIGS. 8 and 9, a storage tank 1 for storing liquefied gas is supported by a large number of support bases 2 and inside a hull 3. A structure that is designed to be installed on the ground has been put to practical use. Storage tank 1 in such an LNG ship
Is an aluminum alloy rectangular tank body 4 whose entire surface is covered with a cold insulation panel 5. The bottom surface of the tank body 1 is flat, and the bottom surface of the support body 2 is horizontal.
It is supported by. Then, in the support portion of the tank body 1 by the support base 2, as shown in FIG. 9, the support base 2 and the cold insulation panel 5 are arranged to absorb the thermal expansion and contraction of the tank body 1.
And a small gap is secured between them and the other heat insulating material 6 such as glass wool is filled therein.

By the way, in this type of liquefied gas carrier, even if the cryogenic liquefied gas stored in the tank body 1 leaks, it reaches the hull 3 and the hull 3 becomes cold. It is necessary to surely prevent such a situation that becomes brittle. Therefore, a material having liquid tightness such as polyurethane foam is adopted as the cold insulation panel 5, and even if the liquefied gas leaks from the tank body 1, it is shielded by the cold insulation panel 5 and leaks to the outside. To prevent the leaked liquid from reaching the hull 3 immediately.

[0004]

However, even if the cold insulation panel 5 having liquid tightness is adopted, the support base 2 and the cold insulation panel 5 are supported by the support base 2 as described above.
Since a gap is secured between the heat insulating material 6 and the heat insulating material 6, even if the heat insulating material 6 is filled, the liquid tightness cannot be secured there.
Therefore, there is a concern that the leaked liquid may drip from the gap. Therefore, in order to prevent the leaked liquid from reaching the hull 3 by any chance, as shown in FIG. 9, for example, a gutter 7 for receiving the leaked liquid is provided below the gap over the entire circumference of the support base 2. Although it has been installed in advance, since the number of the support bases 2 is large, installing the above-mentioned gutter 7 on all of them causes an increase in cost and an effective improvement measure. Was wanted.

[0005]

In view of the above circumstances, the present invention provides a storage tank for liquefied gas in which a whole surface of a rectangular tank body having a flat bottom surface is liquid-tightly covered with a cold insulation panel by a support base. It is applied to a liquefied gas carrier that is installed in the hull by supporting the bottom surface horizontally, and is a hull protection device for preventing the liquid leaked from the tank body from reaching the hull, which is a storage tank of the storage tank. At the four corners of the bottom surface, discharge ports for discharging the leaked liquid leaking from the tank body to the inside of the cold insulation panel to the outside of the cold insulation panel are formed, and the leaked liquid is received below the discharge ports. The feature is that a tray is installed.

When a concave portion such as a pump well is formed on the bottom surface of the tank body, a bulging portion that bulges downward is formed on the cold insulation panel that covers the bottom surface of the tank body, corresponding to the concave portion. It is advisable to install the discharge port also in the bulging portion and install the tray below the discharge port. Further, it is preferable to attach a drain valve to each of the discharge ports, which is normally closed and opens when the leaked liquid reaches the position of the discharge port.

[0007]

In the hull protection device of the present invention, the entire surface of the tank body including the support portion by the support base is liquid-tightly covered with the cold insulation panel so that the liquid leaked from the tank body is shielded by the cold insulation panel. , Leaked liquid is discharged from the discharge ports provided at the four corners of the bottom of the storage tank,
It is received by the tray. In this case, since the bottom surface of the tank body is flat and supported horizontally, the leaked liquid leaking inside the cold insulation panel covering the bottom surface of the tank body is completely stationary on the hull. If it does, it will not flow in either direction, but since the hull is usually oscillating to a large extent, the leaked liquid naturally flows down in either direction, and finally the bottom of the storage tank. Is guided to one of the four corners, reaches the position of the discharge port provided there, and is discharged.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. The LNG carrier to which the hull protection device of the present embodiment is applied is similar to the conventional one shown in FIG. The bottom surface is supported horizontally and installed inside the hull 3. The storage tank 1 is similar to a conventional storage tank in that the entire surface of a tank body 4 made of an aluminum alloy is covered with a cold-insulating panel 5 having liquid tightness such as polyurethane foam. Stand 2
While the liquid-tightness cannot be ensured in the supporting portion of the tank body 4 by the above, in the present embodiment, the liquid-tightness is completely ensured in the supporting portion by the support base 2 due to the structure described later, for example. The leak liquid cannot leak out from the storage tank 1, and the leak liquid leaking inside the cold insulation panel 5 is guided to the four corners of the bottom surface of the storage tank 1 to be discharged.

That is, as shown in FIGS. 1 to 3,
At the four corner positions on the bottom surface of the storage tank 1, there are formed discharge ports 10 for discharging the leaked liquid leaking from the tank body 4 to the inside of the cold insulation panel 5 to the outside of the cold insulation panel 5, and at the same time Below the outlet 10, a tray 11 for receiving the leaked liquid discharged from the discharge port 10 is supported and supported by a support stand 17. A drain valve 12 is attached to each of the discharge ports 10 so as to be normally closed and to automatically open when the leak liquid reaches the position of the discharge port 10 to discharge the leak liquid. Further, in order to promote the natural evaporation of the leaked liquid discharged to the tray 11, the tray 11 is formed of a material having excellent thermal conductivity, and the fins 13 are attached to the inside thereof in a grid pattern.
It is preferable to employ a support base 17 having a cross section as small as possible and excellent heat conduction.

Further, as shown in FIG. 1, a recess 14 such as a pump well is formed on the bottom surface of the tank body 4, and the cold insulation panel 5 covering the bottom surface of the tank body 4 corresponding to the recess 14 is formed. Is formed with a bulging portion 15 bulging downward, and the bulging portion 15 is also formed with a discharge port 10 similar to the above, and a drain valve 12 similar to the above is attached to the bulging portion 15. A tray 11 is installed.

In the hull protection device having the above-described structure, the entire surface of the tank body 4, particularly the entire bottom surface of the tank body 4 including the support portion by the support base 2 is completely liquid-tightly covered by the cold insulation panel 5 as described above. Therefore, even if the liquefied gas leaks from the tank body 4, the leaked liquid immediately leaks to the cold insulation panel 5
The water will not leak to the outside of the tank, and will accumulate inside the cold insulation panel 5 that covers the bottom of the tank body 4.

In this case, since the bottom surface of the tank main body 4 is flat and is supported horizontally, the leaked liquid leaked to the inside of the cold insulation panel 5 covering the bottom surface of the tank main body 4 will not leak. If it is completely stationary, it will not flow in either direction, but normally the hull 3 is always swaying to some extent, so the leaked liquid will naturally flow down in either direction. Eventually, it will be guided to any one of the four corners of the bottom surface of the storage tank 1 or to the bulging portion 15 at the lowest position.

Then, the leaked liquid is guided to the four corners or the bulging portions 15 of the storage tank 1 in this way, and the discharge port 10 is discharged.
When the position is reached, the drain valve 12 is automatically opened as described above, and the leaked liquid is discharged to the tray 11. Tray 11
The leaked liquid that has been discharged into the tank will spontaneously evaporate rapidly, and this will surely prevent the cryogenic leaked liquid from reaching the hull 3.

As described above, according to the hull protection device of the present embodiment, the leaked liquid leaking to the inside of the cold insulation panel 5 is utilized at the four corners of the storage tank 1 or the bulging part 1 by utilizing the swing of the hull 3.
Since it is led to the position of 5, it is possible to prevent a large amount of leaked liquid from accumulating inside the cold insulation panel 5,
The leaked liquid can be efficiently discharged from the discharge ports 10 installed at only 5 places. Since it is sufficient for the hull protection device of this embodiment to install the trays 11 only at the positions of the five outlets 10, it is necessary to install the gutters 7 for all of the large number of support bases 2. Compared with the conventional case, the entire structure can be made much simpler, and a significant cost reduction can be realized.

By the way, although various types of drain valves 12 can be arbitrarily adopted, it is preferable to adopt the structure shown in FIGS. 4 and 5, for example.
The drain valve 12 is a cylindrical valve box 22 mounted on a valve box mounting piece 21 fixed around the discharge port 10.
And a bimetal fixing hardware 24 that is screwed onto the upper portion of the valve box 22 and opens a plurality of valve inlets 23, and a stopper 25 attached to the lower end of the bimetal fixing hardware 24 are arranged in parallel so as to face each other. Bimetal fixing hardware 2 with screws at each upper end
4 has a plate bimetal 26, a rod 27 positioned at the center of the valve box 22, and a stopper 25 at the lower end of each plate bimetal 26. So that the rod 2 engages with the stopper 25.
A coil-opening coil retainer 29, which is slidably fitted to the lower end of 7, and a screw opening 30 on the upper portion of the rod 27, which allows the valve-opening coil to move freely in the vertical direction. A spring holder 31, a valve opening coil spring 32 interposed between the valve opening coil spring holder 31 and the bimetal fixing hardware 24, and the valve opening coil spring holder 3
1 and a coil spring holder 29 for sealing, a coil spring 33 for sealing, a valve plate 34 detachably screwed to the lower end of the rod 27, a lower end surface of the valve box 22 and the valve. It has a structure including a packing 35 for sealing the gap with the plate 34. Further, the plate bimetal 26
Has a structure in which the outer surface side is a high expansion metal and the inner surface side is a low expansion metal, and these two kinds of metals are bonded together and then molded by rolling.
Has a larger spring force than the valve opening coil spring 32.

The operation of the drain valve 12 configured as described above will be described. When a part of the tank body 4 is damaged and the liquefied gas inside leaks to the inside of the cold insulation panel 5, the leaked liquid is discharged from the discharge port 10. It enters the inside of the valve box 22 through the valve inlet 23. When the leaked liquid enters the valve box 22 and flows down, the temperature of the plate bimetal 26 also decreases due to the decrease in the temperature inside the valve box 22 due to the leaked liquid. The plate bimetal 26 has a structure in which the outer surface side is bonded with a high expansion metal and the inner surface side is bonded with a low expansion metal.
Bend outward as shown in. When the stopper 25 at the lower end of the plate bimetal 26 bends from the engaging portion 28 of the sealing coil spring holder 29 to a position where it can be disengaged, the engaging portion 28 of the sealing coil spring holder 29 moves from the stopper 25. Leave in an instant. As a result, the sealing coil spring 33 is released and loses its elasticity, and at the same time, the compression amount of the valve opening coil spring 32 is released, and the rod 27 is pushed down, so that the valve plate 3 is released.
4 moves downward and is in a valve open state. At this time, the compression amount of the valve opening coil spring 32 is determined by the valve opening coil spring holder 31.
It can be adjusted by moving up and down. The leaked liquid that has entered the valve box 22 due to the valve open state is
It will be discharged through between the lower end of 2 and the valve plate 34.

By using the drain valve 12 having such a structure, when the leaked liquid reaches the position of the discharge port 10, the leaked liquid can be quickly discharged, and in the normal time, the drain valve 12 is used. Since it is closed, the cold insulation effect by the cold insulation panel 5 is not impaired.
That is, the drain valve 12 is not installed, and the discharge port 1
When 0 is normally open, the outside room temperature air flows into the inside of the cold insulation panel 5 through the outlet 10, so that the inside temperature of the cold insulation panel 5 is lower than the wall surface temperature of the tank body 4. There is a concern that a high-temperature air flow will be generated, which may impair the cold insulation effect, but as described above, the drain valve 12 always closes the discharge port 10 to prevent the inflow of external air from the discharge port 10. By
Such a thing can be prevented in advance.

Further, in the hull protection device of this embodiment, as described above, it is necessary to completely liquid-tightly cover the entire bottom surface of the tank body 4 with the cold insulation panel 5, and therefore the support base 2 supports the tank body 4. Since liquid tightness must be ensured also in the parts, it is preferable to adopt a structure as shown in FIG. 7, for example.

That is, a horizontal overhanging portion 40 that overhangs to the outer peripheral side is integrally formed at a middle position in the height direction of the support base 2, and a downward step portion 41 is formed on the outer peripheral lower surface of the overhanging portion 40. I'll do it. Then, the lower surface of the cold insulation panel 5 attached to the bottom surface of the tank body 4 is brought into sliding contact with the upper surface of the overhanging portion 40, and a slight gap is secured between the side end surface of the cold insulation panel 5 and the side surface of the support base 2. A heat insulating material 42 such as glass wool is filled in. Further, a relatively soft cold insulation material 43 such as polyethylene foam is provided on the lower surface of the cold insulation panel 5, and the edge of this cold insulation material 43 is bonded to the side surface of the overhanging portion 40 and the step portion 41 facing downward. Accordingly, a liquid tight tape 44 is attached between the cold insulating material 43 and the overhanging portion 40.

With such a structure, when the tank body 4 expands or contracts due to heat, the hard cold insulation panel 5 has the overhanging portion 40.
The sliding surface is able to follow the thermal deformation by sliding on the upper surface, and the relatively soft cooler 43 can freely expand and contract by heat, so that it is possible to secure the liquid tightness while absorbing the thermal deformation. It is possible to prevent the leaked liquid from leaking.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes may be made without departing from the scope of the present invention. Of course.

[0022]

As described above, in the hull protection device of the present invention, since the leaked liquid discharge ports are provided at the four corners of the storage tank, the leaked liquid leaked from the tank body to the inside of the cold insulation panel will not leak to the hull. The swing naturally guides them to the positions of the discharge ports. Therefore, it is sufficient to install the tray only at the positions of the discharge ports, so it is ensured that the leaked liquid reaches the hull by any chance. In addition to being able to prevent it, the whole structure can be much simpler than the conventional case where it was necessary to install a gutter on all of a large number of support bases, and a significant cost reduction can be realized. Produce an effect. If the cold insulation panel that covers the bottom surface of the tank body is formed with bulges corresponding to the recesses such as pump wells, the bulging parts are also provided with the same outlets and trays. There is an advantage that the leaked liquid led to the outlet can be discharged without any trouble.In addition, a drain valve that is normally closed and opens only when the leaked liquid reaches the position of the discharge port must be attached to the discharge port. Due to
There is an advantage that it is possible to prevent air from externally flowing into the inside of the cold insulation panel from the outlet and impair the cold insulation effect.

[Brief description of drawings]

FIG. 1 is a transverse cross-sectional view showing a storage tank equipped with a hull protection device according to an embodiment of the present invention.

FIG. 2 is a plan sectional view of a bottom portion of the storage tank.

FIG. 3 is an enlarged view showing a main part of the hull protection device.

FIG. 4 is a vertical cross-sectional view showing a structural example of a drain valve in the ship body protection device.

FIG. 5 is a transverse sectional view of the drain valve.

FIG. 6 is a vertical cross-sectional view showing a state of the drain valve when the valve is open.

FIG. 7 is a cross-sectional view showing a structural example of a support portion of a storage tank including the hull protection device.

FIG. 8 is a diagram showing a storage tank installed in a hull of a liquefied gas carrier.

FIG. 9 is an enlarged view of a support portion of the storage tank.

[Explanation of symbols]

 1 Storage tank 2 Support stand 3 Hull 4 Tank body 5 Cooling panel 10 Discharge port 11 Tray 12 Drain valve 14 Recessed portion 15 Swelling portion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuhiko Gyouto 2-1-1 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Ltd. Tokyo No. 1 factory (72) Inventor Yushi Kakuda 2-chome, Toyosu, Koto-ku, Tokyo No. 1 No. 1 Ishikawajima Harima Heavy Industries Ltd. Tokyo No. 1 factory

Claims (3)

[Claims] 1. A storage tank for liquefied gas, in which the whole surface of a rectangular tank body having a flat bottom surface is liquid-tightly covered by a cold insulation panel, is installed in the hull by supporting the bottom surface horizontally by a support base. Applied to liquefied gas carriers
A hull protection device for preventing leaked liquid from the tank body from reaching the hull, and cools the leaked liquid leaked from the tank body to the inside of the cold insulation panel at the four corners of the bottom surface of the storage tank. A hull protection device for a liquefied gas carrier, characterized in that discharge ports for discharging the liquid to the outside of the panel are formed, and trays for receiving leaked liquid are installed below the discharge ports. 2. A cold insulation panel that covers the bottom surface of the tank body,
A bulging portion that bulges downward is formed corresponding to the concave portion formed on the bottom surface of the tank body, and the discharge port is installed in the bulging portion, and the tray is installed below the discharge port. The hull protection device for a liquefied gas carrier according to claim 1, wherein 3. A drain valve, which is normally closed and is opened when the leaked liquid reaches the position of the discharge port, is attached to each of the discharge ports.
A hull protection device for a liquefied gas carrier according to.