JPH0473040B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a support structure for a cryogenic tank in a cryogenic vessel such as a cryogenic liquefied gas carrier, particularly an LNG carrier.

The cold walls of low-temperature tanks such as low-temperature liquefied gas carriers are
In order to maintain cold insulation performance, it is necessary to make airtight areas where air circulation between the inner and outer layers of the cold insulation layer, that is, large convection, is likely to occur, such as the area around the tank support block that penetrates the cold insulation layer. If liquid leaks, it is necessary to direct the leaked liquid to a safe location.

However, in the conventional support structure for a low-temperature tank, as shown in Fig. 1, the through-hole surface d of the cold insulation layer c through which the support block b of the tank a passes is completely bonded to the outer surface of the support block b using an adhesive. Alternatively, in case of leakage, the parts are partially bonded and the low temperature liquid leaked from the bonded part is collected using a leakage liquid receiver (not shown).With the former structure, it is difficult to completely bond the inner bottom plate e. Both structures were unable to satisfactorily meet the requirements mentioned above, such as the use of high-grade low-temperature materials for the second structure, and the latter structure causing large convection in the unbonded areas, resulting in incomplete cold storage performance.

The present invention has been made to solve the above-mentioned problem, and includes a support structure for a low-temperature tank in which a support block penetrates through a cold insulation layer that keeps the tank cool and supports the tank with a support block. The lower open end of the gap between the support block and the support block is hermetically closed by a gutter-like mechanism attached around the support block, and an opening is formed at the bottom of the gutter-like mechanism by cooling and contraction. This relates to a support structure for a low-temperature tank, which is characterized by having a partition with an airtight breaking mechanism configured as shown in FIG. This has the advantage of ensuring that the cooling effect is maintained, and that in the event of a tank leakage, the airtight breaking mechanism operates to guide the leaked liquid to a recovery device, ensuring safety.

Embodiments of the present invention will be described below with reference to the drawings. 2 and 3 show a first embodiment of the present invention, and in the figures, reference numeral 1 is the bottom plate of the LNG tank 2, 3 is the cold insulation layer, 4 is the inner bottom plate, 5 is the support base, and 6 is the bottom plate of the LNG tank 2.
penetrates the cold insulation layer 3 and supports the LNG tank 2 on the support stand 5
It is a support block made of a low temperature resistant material that is supported on top and has a leakage liquid receiver 8 around it, and a small gap 9 between the through-hole surface of the cold insulation layer 3 and the outer surface of the support block 6 is filled with glass wool, and the gap is filled with glass wool. 9 lower opening end 1
0 is hermetically closed by a tub-like mechanism 12 with a square cross section attached around the support block 6.

The side parts 13, 13 of the gutter-like mechanism 12 are made of metal or plywood, and the bottom part is made of a material that self-destructs depending on the temperature. A membrane 14 made of a polyethylene polymer configured to self-destruct by heat shrinkage is stretched in an airtight manner.

Next, the operation of this device will be explained. Normally, the gap 9 in the cold insulation layer is hermetically sealed from the outside air by the thin film 14, so there is no risk of large convection occurring, and the cold insulation effect is reliably maintained. In addition, in the event that a leak occurs from the tank, the leaked liquid (LNG) will be transferred to the support block 6 along the top surface of the cold insulation layer 3.
It flows towards the surrounding gap 9 (arrow g) and is then discharged through this gap 9 into the trough-like mechanism 12 (arrow h) and accumulates on the membrane 14. Here, the thin film 14 is cooled to around minus 160° C., self-destructs, and further falls onto the leakage liquid receiver 8 to be collected. Therefore, the support stand 5 and the inner bottom plate 4 are not exposed to leaked liquid (LNG) and are safe.

A second embodiment of the invention is shown in FIGS. 4 and 5. In this example, a short tube 16 made of metal or plywood is attached to an appropriate position on the bottom 15 of the bucket-like mechanism, and a notch 18 is installed between two bottom plates 17, which are airtightly attached inside the short tube 16. It is made by sandwiching engraved plastic thin plates 19, and holes 20, 20 are provided in the upper and lower bottom plates 17, 17 so that the notches 18 are exposed. In this example as well, the leaked LNG was placed on a thin plastic plate 19.
When the thin plate 19 heat-shrinks, the notch 18
This causes a crack and self-destructs.

FIG. 6 shows a third embodiment of the present invention. In this example, a metal plate 23 (or plastic sheet) is attached to the inside of the short pipe 16 shown in Fig. 4 using an adhesive 22 that becomes brittle at low temperature when the temperature drops to approximately a predetermined temperature (-160°C). When leaked liquid (LNG) comes into contact with the adhesive 22, the adhesive 22 becomes brittle and heat-shrinks, causing the adhesive to peel off and create a rupture.

FIG. 7 shows a fourth embodiment of the present invention. In this example, a bimetal 24 with a cutter and a plastic thin film 25 are placed inside the short pipe 16 shown in FIG.
6, 26, and when cooled to a predetermined temperature, the cutter-equipped bimetal 24 deforms as shown by the two-dot chain line, breaks the thin film 25, and allows the leaked liquid to pass through.

A fifth embodiment of the invention is shown in FIG. This example is the bimetal 24 with cutter in Figure 7.
A snap-type bimetal 27 is attached in place of the second embodiment, and other than that, there is no difference from the fourth embodiment. In this example as well, the snap-type bimetal 27 is deformed at low temperatures as shown by the two-dot chain line, and the thin film 25 is destroyed.

A sixth embodiment of the invention is shown in FIG. In this example, a short tube 28 made of a material with low heat shrinkage (for example, INVAR) is attached to the bottom of a bucket-like mechanism (not shown), and a lump 29 made of a material with high heat shrinkage (for example, Teflon) is press-fitted inside the short tube 28. When the lump 29 is cooled by the leaked liquid, it shrinks due to heat and falls downward (arrow j), creating a path for the leaked liquid.

Note that the present invention is not limited to the above-described embodiments; for example, the cross section of the bucket-like mechanism may not be rectangular, and various other changes may be made without departing from the gist of the present invention. Of course.

Since the support structure for a low temperature tank of the present invention has the above-described configuration, it exhibits the following excellent effects.

() Normally, the cold insulation wall is kept in an airtight structure to prevent large convection, and in the event of a tank leak, an airtight breaking mechanism is installed to automatically pass the leaked liquid, increasing the cold insulation effect and increasing safety. can be improved.

() As a result of paragraph (), it is no longer necessary to manufacture the inner bottom plate using high-grade low-temperature resistant materials as in the past, and it is also possible to install a leakage liquid recovery device effectively without losing the airtightness of the cold insulation wall. becomes possible.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the support structure of a conventional low-temperature tank, FIGS. 2 and 3 show a first embodiment of the present invention, and FIG. 2 is a cut side view showing the overall arrangement of the device. 3 is an enlarged view of the part in FIG. 2, FIGS. 4 and 5 show the embodiment of the invention shown in FIG. 2, FIG. 4 is a cutaway side view of the airtight breaking mechanism, and FIG. The arrow views from the − direction in FIGS. 6 to 8 are the third to fifth views of the present invention, respectively.
FIG. 9 is a partially cutaway perspective view of the airtight breaking mechanism showing a sixth embodiment of the present invention. In the figure, 2 is an LNG tank, 3 is a cold insulation layer, 6 is a support block, 8 is a leakage liquid receiver, 9 is a gap, 10 is an open end, 12 is a bucket-like mechanism, 14 and 25 are thin films, 19
22 is a thin plate, 22 is an adhesive, 24 is a bimetal with a cutter, 27 is a switch-type bimetal, and 29 is a lump.

Claims (1)

[Claims] 1. In a support structure for a low-temperature tank in which the tank is supported by a support block that penetrates a cold insulation layer that keeps the tank cold, the lower opening end of the gap between the through hole of the cold insulation layer and the support block is It is airtightly closed by a trough-like mechanism attached around the support block, and the bottom of the trough-like mechanism is equipped with a partition having an airtight breaking mechanism configured to create an opening by cooling and contraction. A support structure for a low-temperature tank, characterized by having a tank leakage liquid recovery device provided below.