JPH0717467A - Device for evaporating leaked cargo - Google Patents

Abstract

PURPOSE:To completely evaporate the liquefied gas of low temperature of an allowable leakage only with the heat held by the heat accumulating material by forming a drip pan provided to the lower part of a tank in the double-welled structure, and packing the heat accumulating material of large heat capacity into the space partitioned by this double-walled surface. CONSTITUTION:A leaked cargo evaporating device protects the hull even when, e.g. the liquefied gas of low temperature is leaked from a cracked part of a low temperature liquefied gas tank and brought into contact with the hull. A drip pan provided to the lower part of a tank is formed in the square shape, and the bottom part 9 is formed into a double bottom structure by the upper and lower bottom plates 11, 12. Water W as the heat accumulating material is filled into the space partitioned by the bottom plates 11, 12. In addition, the bottom part 9 and the side parts 10 of the drip pan 8 are covered by the heat accumulating material 14. When the liquid low temperature liquefied gas leaked from the tank is dripped in the drip pan 8, the total amount of the low temperature liquefied dripped gas is evaporated by supplementing the heat of evaporation from the water W.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature liquefied gas tank which is cracked and directly leaks from the low-temperature liquefied gas.
The present invention relates to a leaked cargo vaporization device which is supposed to come into contact with a hull, and whose main purpose is to protect the hull even in such a case.

[0002]

2. Description of the Related Art Conventionally, a secondary barrier has been provided between a low temperature liquefied gas tank and a hull in case of an emergency situation in which a crack occurs in the tank. The setting range of the secondary barrier that prevents the low-temperature liquefied gas leaking from the cracked part of the tank from colliding with the hull structure and causing the hull structure to become brittle and break at a low temperature depends on the tank type. However, in the stand-alone type B tank, a storage facility or a discharge facility for the low temperature liquefied gas leaked from the tank is required in addition to the secondary barrier.

Of course, a vaporization system is also possible, but in the case of natural vaporization, it is necessary to secure a large heat transfer area of the vaporizer, and in the case of forced vaporization, auxiliary equipment such as an evaporator and piping is required. Becomes

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to overcome the above-mentioned conventional problems, and its object is to increase the heat transfer area of a vaporizer, and to improve the heat transfer area of an evaporator or piping. It is to provide a leaked cargo vaporizer that does not require auxiliary equipment.

[0005]

In order to achieve the above object, the leaked cargo vaporizer of the present invention has a double-wall structure for a part or all of a drip pan installed below a tank, and the double-wall structure. It is characterized in that the space partitioned by the wall surface is filled with a heat storage material having a large heat capacity.

When the low-temperature liquefied gas in a liquid state leaking from the low-temperature liquefied gas tank flows down into the drip pan, the liquid low-temperature liquefied gas is stored in the double-structured drip pan as a heat storage material having a large heat capacity. The entire amount is vaporized by receiving the heat of vaporization from. Here, as a material for the drip pan, a low temperature resistant material such as stainless steel or aluminum alloy is preferable.

Further, the heat storage material is preferably a material having a large heat capacity such as sand, slag, water containing antifreeze, antifreeze, oil and the like. Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a spherical low temperature liquid gas tank, which is a cylindrical support structure 2
It is supported on the hull structure 3 by.

Reference numeral 4 denotes a heat insulating structure wall for cooling that surrounds the outside of the spherical low temperature liquid gas tank 1, and a space 5 is provided between the low temperature liquid gas tank 1 and the heat insulating structure wall 4 for cooling.
Exists. Space 5 on the northern hemisphere side of the low-temperature liquid gas tank 1
a and the space 5b on the southern hemisphere side are communicated with each other by a plurality of communication holes 6 formed in the support structure 2. At the bottom of the heat insulating structure wall 4, the heat insulating structure wall 4 and the low temperature liquid gas tank 1 are provided.
A communication pipe 7 that reaches the space 5 between the two is attached, and a drip pan 8 that constitutes the vaporizer of the present invention is provided immediately below the communication pipe 7.

The drip pan 8 is in the shape of a box, and the bottom portion 9 has a double bottom as shown in FIG. The space W partitioned by the upper and lower bottom plates 11 and 12 is filled with water W as a heat storage material.
Furthermore, the bottom portion 9 and the side wall portion 10 of the drip pan 8 are
It is covered with the heat insulating material 14. Now, when the low temperature liquefied gas R in a liquid state leaked from the low temperature liquefied gas tank 1 flows down into the drip pan 8, the liquid low temperature liquefied gas R is
The entire amount of the vaporized water is vaporized by receiving the heat of vaporization from the water W having a large heat capacity contained in the drip pan 8 having a double structure. In the above embodiment, only the bottom portion 9 of the drip pan 8 has a double structure, but the entire drip pan 8 may have a double structure.

[0010]

EXAMPLE A 1.5-meter square drip pan (see FIG. 2) filled with water in a double-bottomed space was used to vaporize an allowable amount of liquefied gas (LNG) leaked from a low-temperature liquefied gas tank. However, the whole amount could be completely vaporized only by the retained heat of water filled in the double structure bottom of the drip pan.

Here, the space at the bottom of the drip pan [1500 mm
The heat capacity H of water in (width) × 1500 mm (length) × 250 mm (height)] is as shown in equation (1). That is, H = (1.5 × 1.5 × 0.25) × 1000 × {79.7 + 0.4 × 160
} = 80831 (kcal) (1) The leakage amount M of the low-temperature liquefied gas that can be vaporized with the heat capacity H (kcal) of this water is as shown in equation (2). That is, M = 80831 (kcal) / 122 (kcal / kg) = 662 (kg) = 1558
(Liters) (2) On the other hand, the allowable leak amount m, that is, 1 after the leak is discovered
The leakage amount of the liquefied gas in the liquid state that leaks for 5 days is defined as shown by the equation (3), for example.

That is, m = 5 (liter / h) × 1/2 × 24 (h) × 15
(Days) = 900 (liters) (3) Therefore, comparing the values of equation (2) and equation (3), the water filled in the space at the bottom of the 1.5 m square drip pan is It can be seen that the low-temperature liquefied gas having an allowable leak amount can be completely vaporized.

[0013]

As described above, according to the present invention, a part or the whole of the drip pan installed below the tank has a double wall structure, and the heat capacity is kept in the space partitioned by the double wall surface. Since it is filled with a large amount of heat storage material, the heat transfer area of the vaporizer is made particularly large, and the storage of heat storage material filled in the double structure bottom of the drip pan without the need for auxiliary equipment such as an evaporator or piping The low temperature liquefied gas with an allowable leak amount can be completely vaporized only by the retained heat.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a low temperature liquefied gas tank having a leaked cargo vaporizer according to the present invention.

FIG. 2 is an enlarged vertical sectional view of a leaked cargo vaporizer according to the present invention.

[Explanation of symbols]

 1 Low-temperature liquefied gas tank 8 Drip pan 11, 12 Wall surface 13 Space W Heat storage material with large heat capacity

Claims (1)

[Claims] 1. A leaked cargo in which a part or all of a drip pan installed below a tank has a double wall structure, and a space partitioned by the double wall surface is filled with a heat storage material having a large heat capacity. Vaporizer.