JP2582772Y2 - Tank cooling system for liquefied gas carrier - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for pre-cooling a liquefied gas storage tank in a liquefied gas carrier.

[0002]

2. Description of the Related Art A liquefied natural gas carrier (hereinafter, referred to as an LNG carrier) carries and transports liquefied natural gas (hereinafter, referred to as LNG) in a tank installed on a hull.
In recent years, an LNG ship of a type in which the tank is of a self-standing square type and is stored in the hull has been developed.

[0003] Since the inside of the tank contains LNG at a low temperature of -162 ° C, the tank is devised for that purpose. As an example, it is necessary to prevent the cool air from the LNG housed inside from being directly transmitted to the hull, so that the outer surface of the tank is covered with a cold insulation panel, and the inside and outside of the tank are insulated.

When LNG at -162 ° C. is allowed to flow into a tank placed at room temperature, thermal stress is generated inside the tank due to rapid cooling of the tank wall, and in the worst case, There is also a concern that the tank wall may be damaged. Therefore, it is necessary to cool (pre-cool) the tank wall to a predetermined temperature before flowing LNG into the tank.

Conventionally, as a cooling device for pre-cooling a liquefied gas storage tank of this type, a liquefied gas having an injection nozzle at an upper part in a tank is particularly used as a tank cooling device for a liquefied petroleum gas carrier (hereinafter referred to as an LPG ship). A circulation pipe is provided, and liquefied petroleum gas (hereinafter, LP)
G) is introduced to spray LPG from the injection nozzle, and the tank wall is indirectly cooled by vapor generated in the tank.

[0006]

However, the temperature of LPG is about -60 ° C., which is higher than that of LNG, and the temperature difference from room temperature is small. Therefore, even if the mist LPG directly contacts the tank wall, However, there is no problem that the tank wall is damaged by thermal stress. However, when this cooling device is applied to LNG, there is a problem that it is difficult to pre-cool particularly in the vicinity of a ceiling plate. On the other hand, for example, the tank may be damaged due to direct contact of LNG with a tank wall. There are disadvantages. Therefore, in the case of LNG, the structure of the cooling device needs to be carefully considered,
A cooling device that can efficiently and reliably pre-cool the tank has not been realized yet.

The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a tank cooling device for a liquefied gas carrier that can efficiently and reliably pre-cool a tank. .

[0008]

In order to achieve the above object, a tank cooling device for a liquefied gas carrier according to the present invention introduces a liquefied gas into a liquefied gas storage tank stored in the hull, and a tank cooling system of the liquefied gas carrier for performing pre-cooling of the tank, the horizontal in the space portion of the tank upper
The liquefied gas is bent in the plane, and sprays the liquefied gas introduced into the pipe without contacting the tank inner wall.
The main liquefied gas flow pipe having a plurality of nozzles adjusted, and the space between the ceiling plate of the tank and the main liquefied gas flow pipe is bent and disposed in a horizontal plane, and introduced into the pipe. The ceiling without contacting the liquefied gas with the tank inner wall
Angle adjusted to spray into space close to plate
A plurality of nozzles, each having a smaller diameter than the main liquefied gas flow pipe
And a sub-liquefied gas distribution pipe.

[0009]

According to the tank cooling device for a liquefied gas carrier of the present invention, the liquefied gas is sprayed from the main liquefied gas distribution pipe disposed in the upper space in the tank, so that the liquefied gas flows downward in the tank. While falling toward the tank, the tank wall below the main liquefied gas flow pipe is mainly cooled through the vapor in the tank. Further, the liquefied gas sprayed from the sub-liquefied gas flow pipe provided in the space between the ceiling plate of the tank and the main liquefied gas flow pipe causes the tank ceiling plate and its The periphery is cooled.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the tank cooling device of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a state in which a spray line (liquefied gas flow pipe) of a tank cooling device is installed in a tank of an LNG ship. The tank 1 is schematically constituted by a wall portion 5 constituted by a side plate 2, a ceiling plate 3, and a bottom plate 4, and a reinforcing rib 6 formed on an inner surface of the wall portion 5.

A spray line 7 is a main spray line (main liquefied gas flow pipe) provided in the upper part of the tank 1.
8, ceiling spray line (sub-liquefied gas distribution pipe) 9, and recovery spray line 10 extending in the vertical direction in tank 1.
LN flowing through the pipe
G is sprayed from the spray line 7 into the tank 1, the vapor in the tank 1 is cooled by the mist LNG, and the wall 5 of the tank 1 is cooled by the vapor in the cooled tank 1. Has become.

FIG. 2 is a view showing a spray line 7 provided in the tank 1, wherein reference numeral 8 is a main spray line, 9 is a ceiling spray line, and 10 is a recovery spray line.

The main spray line 8 is formed by bending a pipe having an inner diameter of 50 mm, and is installed in a horizontal direction above the inside of the tank 1. FIG.
The lines 8a and 8b shown in FIG. 3 have their extended ends led out of the tank, and have LNG supply mechanisms (not shown) including an LNG supply source and a supply pump, and an LNG supply mechanism (described later).
NG circulation mechanisms are connected, and these mechanisms
NG is introduced into the main spray line 8.

The ceiling spray line 9 is formed by bending a pipe having an inner diameter of 25 mm, which is thinner than the main spray line 8.
It is installed in the space between the main spray line 8 and the main spray line 8 in a horizontal direction. Also in the ceiling spray line 9, as in the case of the main spray line 8, the lines 9a and 9b shown in FIG. 2 have extended ends led out of the tank, and an LNG supply mechanism (not shown) and L
NG circulation mechanisms are connected, and these mechanisms
NG is introduced into the ceiling spray line 9.

Both the main spray line 8 and the ceiling spray line 9 have nozzles 11 at regular intervals.
11, ... are installed. This nozzle 11 is for spraying the LNG introduced into the main spray line 8 and the ceiling spray line 9 into a mist and spraying it into the tank 1, and as shown in FIG. To favorite,
The spray direction is arranged so as to face one side or the other side of the spray line. Furthermore, each nozzle 1
The angle 1 is set slightly upward from the horizontal direction so that the sprayed LNG does not directly hit the wall 5 of the tank 1.

The recovery spray line 10 has an inner diameter of 5 mm.
A bent portion is provided in the middle of a 0 mm pipe, and is installed so as to extend in the vertical direction of the tank 1. A spray pump 12 is connected to a lower end of the tank 1, An LNG circulation mechanism (not shown) is connected to an upper end led out. The spray pump 12 is for collecting LNG remaining at the bottom of the tank 1 into the LNG circulation mechanism.

The procedure for pre-cooling the tank 1 using the tank cooling device 13 having the spray line 7 having the above-described configuration will be described below. First, as a step before loading, when the tank 1 is empty at normal temperature and the tank 1 is empty,
By operating the NG supply mechanism, LNG is introduced into the main spray line 8 and the ceiling spray line 9 and the LNG is supplied to the nozzle 1.
Are sprayed into the tank 1 from 1, 11,. Then, LNG vapor is generated from the mist LNG, and the wall portion 5 of the tank 1 is cooled through the vapor to perform pre-cooling. LNG stored in tank 1 is -16
2 ° C., whereas the wall 5 of the tank 1 is at −110 ° C.
When it is cooled to the extent, the LNG supply mechanism is stopped to complete the pre-cooling, and the LNG loading is started.

Next, when the LNG is transported to the destination and the loaded LNG is taken out of the tank 1, the tank 1 is not left empty at all, and a small amount of LNG remains at the bottom of the tank 1. Let it be. In this state, once again, the tank 1
When LNG is stored in the spray pump 12
Is operated to collect the residual LNG in the LNG circulating mechanism, while activating the LNG circulating mechanism to introduce the residual LNG into the main spray line 8 and the ceiling spray line 9 to cause the nozzle 1
Are sprayed into the tank 1 from 1, 11,. The wall 5 of the tank 1 is cooled and pre-cooled by the same operation as described above, and LNG can be stored in the tank 1.

In the tank cooling device 13 having the above configuration, a large amount of LNG is supplied from the main spray line 8 having a large diameter.
Is sprayed, and while the atomized LNG falls from the vicinity of the main spray line 8 to the lower part of the tank 1, the wall 5 of the tank 1 over a wide area below the main spray line 8 is cooled. Further, since the LNG sprayed from the ceiling spray line 9 falls from above the main spray line 8, the upper part of the tank 1, which is hardly cooled by the LNG from the main spray line 8, particularly the ceiling plate 3 and its peripheral part are cooled. Is done. Therefore, this spray line 7
According to the configuration, the entire wall 5 of the tank 1 can be efficiently cooled.

Since the angles of the nozzles 11, 11,... Are set so that the sprayed LNG does not directly contact the wall 5 of the tank 1, the wall 5 of the tank 1 is
The cooling device is indirectly cooled via the vapor in the tank 1, and this cooling device can reliably prevent the wall 5 of the tank 1 from being damaged by thermal stress.

Further, once the transportation of the LNG has been completed, the tank cooling device 13
G, the remaining LNG in the tank 1 is reduced to LN
Since it is configured to perform pre-cooling by circulating by the G circulation mechanism, there is no need to introduce new LNG for pre-cooling except when the inside of the tank 1 is completely empty.
Precooling can be performed promptly.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and the configuration of the main spray line 8, the ceiling spray line 9, the arrangement of the nozzles 11, etc. Various design changes can be made in the specific configuration of each part.

[0023]

As described above in detail, according to the tank cooling device of the liquefied gas carrier of the present invention, the liquefied gas is sprayed from the main liquefied gas flow pipe provided in the space above the tank. The liquefied gas is sprayed from the sub-liquefied gas flow pipe provided in the space between the tank ceiling plate and the main liquefied gas flow pipe. The lower tank wall portion is cooled, and the liquefied gas from the sub-liquefied gas flow pipe cools the tank ceiling plate and its peripheral portion. Therefore, the tank cooling device of the present invention can perform pre-cooling of the tank efficiently and reliably.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a tank cooling device for a liquefied gas carrier according to the present invention.

FIG. 2 is a perspective view showing a spray line in the embodiment.

[Explanation of symbols]

 Reference Signs List 1 tank 3 ceiling plate 8 main spray line (main liquefied gas flow pipe) 9 ceiling spray line (secondary liquefied gas flow pipe) 11 nozzle 13 tank cooling device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akita Shinta 11-1 Kitahama-cho, Chita-shi, Aichi Prefecture Ishikawajima-Hari Ma Heavy Industries Co., Ltd. Aichi Factory (56) References JP-A-57-114096 (JP, A) JP-A-50-20487 (JP, A) JP-B-36-23283 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) B63B 25/16 B65D 88/12

Claims (1)

(57) [Scope of request for utility model registration] 1. A tank cooling device for a liquefied gas carrier for introducing a liquefied gas into a liquefied gas storage tank stored in a hull and pre-cooling the tank, wherein a horizontal surface is formed in a space above the tank. The liquefied gas introduced into the pipe is bent inside the pipe and contacts the tank inner wall.
Nozzles that are angled to spray without spraying
A main liquefied gas flow pipe having a nozzle, bending of in a horizontal plane in the space portion between the ceiling plate of the tank the main liquefied gas flow pipe
Which is arranged, a tank inner wall liquefied gas introduced into the tube
Into the space close to the ceiling plate without contact
With multiple nozzles angled to fog,
A tank cooling device for a liquefied gas carrier, comprising: a sub-liquefied gas flow pipe having a smaller diameter than the main liquefied gas flow pipe .