JPH0685192U - Tank cooling system for liquefied gas carriers - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a tank cooling device for a liquefied gas carrier that can efficiently and reliably precool a tank. [Structure] A tank cooling device 13 is arranged in a space above the tank 1 so as to extend horizontally, and a nozzle 11 for diffusing and spraying LNG introduced into a pipe to the outside.
Is installed in the space between the main spray line 8 of the tank 1 and the ceiling plate 3 of the tank 1 so as to extend in the horizontal direction.
And a ceiling spray line 9 provided with a nozzle 11 for diffusing and spraying into a space portion close to.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a cooling device for precooling a liquefied gas storage tank in a liquefied gas carrier.

[0002]

[Prior art]

 A liquefied natural gas carrier (hereinafter referred to as an LNG carrier) stores liquefied natural gas (hereinafter referred to as LNG) in a tank installed on a hull, and in recent years, the tank is of a self-supporting rectangular type. However, a type of LNG ship has been developed which is designed to be stored inside the hull.

Since LNG at a low temperature of −162 ° C. is accommodated inside the tank, 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 the outer surface of the tank is covered with a cold insulation panel, and the inside and outside of the tank are insulated.

Further, when LNG at −162 ° C. is allowed to flow into a tank placed at room temperature as it is, thermal stress is generated inside due to rapid cooling of the tank wall, and in the worst case, There is also concern that the tank wall may be damaged. Therefore, when injecting LNG into the tank, it is always necessary to cool (precool) the wall of the tank to a predetermined temperature in advance.

Conventionally, as a cooling device for precooling a liquefied gas storage tank of this kind, particularly as a tank cooling device for a liquefied petroleum gas carrier (hereinafter referred to as an LPG ship), an injection nozzle is provided in the upper part of the tank. A liquefied gas flow pipe is installed, and liquefied petroleum gas (hereinafter, referred to as LPG) is introduced into the liquefied gas flow pipe to spray LPG from the injection nozzle. Something to cool is provided.

[0006]

[Problems to be solved by the device]

 By the way, the temperature of LPG is around -60 ° C, which is higher than that of LNG, and the temperature difference from room temperature is small. Therefore, even if the atomized LPG directly contacts the tank wall, the thermal stress causes There is no problem of damage. However, when this cooling device is applied to LNG, there is a problem that it is difficult to precool the area around the ceiling plate in particular, while LNG may come into direct contact with the tank wall and damage the tank. There is a disadvantage. Therefore, in the case of LNG, it was necessary to carefully consider the structure of the cooling device, and a cooling device capable of efficiently and reliably precooling the tank was not yet realized.

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

[0008]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, a tank cooling device for a liquefied gas carrier according to the present invention is a liquefied gas carrier for introducing liquefied gas into a liquefied gas storage tank stored in a hull to precool the tank. A tank cooling device of the present invention, which is provided with a nozzle that is disposed so as to extend horizontally in the space above the tank and that spreads the liquefied gas introduced into the pipe to the outside and sprays it. The liquefied gas flow pipe is arranged in a space between the ceiling plate of the tank and the main liquefied gas flow pipe so as to extend horizontally, and the liquefied gas introduced into the pipe is brought close to the ceiling plate. It is characterized by comprising a sub-liquefied gas flow pipe having nozzles for diffusing into the space and spraying.

[0009]

[Action]

 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 arranged in the space above the tank, so that the liquefied gas is directed downward in the tank. While falling, the tank wall below the main liquefied gas flow pipe is cooled mainly via the vapor in the tank. In addition, the liquefied gas sprayed from the auxiliary liquefied gas flow pipe disposed in the space between the ceiling plate of the tank and the main liquefied gas flow pipe causes the tank ceiling plate and The surrounding area is cooled.

[0010]

【Example】

 An embodiment of the tank cooling device of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a state where 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 roughly configured by a wall portion 5 formed by the side plate 2, the ceiling plate 3, and the bottom plate 4, and a reinforcing rib 6 formed on the inner surface of the wall portion 5.

The spray line 7 includes a main spray line (main liquefied gas flow pipe) 8, a ceiling spray line (secondary liquefied gas flow pipe) 9 arranged in an upper part of the tank 1, and a vertical direction in the tank 1. The LNG flowing in the pipe is sprayed from the spray line 7 into the tank 1, and the vapor in the tank 1 is cooled by the atomized LNG. The wall portion 5 of the tank 1 is cooled by the cooled vapor in the tank 1.

FIG. 2 is a view showing the spray line 7 arranged in the tank 1. 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 tubular body having an inner diameter of 50 mm, and is installed horizontally above the inside of the tank 1. Lines 8a and 8b shown in FIG. 2 have their extended ends led out of the tank, and have LNG supply sources (not shown), an LNG supply mechanism including a supply pump, and an LNG circulation mechanism described later at this end. They are connected and LNG is introduced into the main spray line 8 by these mechanisms.

The ceiling spray line 9 is formed by bending a pipe body having an inner diameter of 25 mm, which is thinner than the main spray line 8, and is formed in the upper part of the tank 1, the ceiling plate 2 and the main spray line 8. It is installed horizontally in the space between and. Similarly to the case of the main spray line 8, in the Amai spray line 9 as well, the extended ends of the lines 9a and 9b shown in FIG. 2 are led out of the tank, and an LNG supply mechanism (not shown) is provided at this end. An LNG circulation mechanism is connected, and LNG is introduced into the ceiling spray line 9 by these mechanisms.

Nozzles 11, 11, ... Are installed at regular intervals on both the main spray line 8 and the ceiling spray line 9. The nozzle 11 is for atomizing LNG introduced into the main spray line 8 and the ceiling spray line 9 and spraying it into the tank 1. As shown in a part of FIG. Every other time, the spray direction is arranged so as to face one side or the other side of the spray line. Furthermore, the angle of each nozzle 11 is set slightly upward from the horizontal direction, and the LNG to be sprayed is not directly applied to the wall portion 5 of the tank 1.

Further, the recovery spray line 10 has a bent portion provided in the middle of a tubular body having an inner diameter of 50 mm and is installed so as to extend in the vertical direction of the tank 1, and has a lower end in the tank 1. A spray pump 12 is connected to the portion, and an LNG circulation mechanism (not shown) is connected to the upper end portion led out of the tank 1. The spray pump 12 is for collecting LNG remaining on the bottom of the tank 1 into the LNG circulation mechanism.

A procedure for precooling the tank 1 using the tank cooling device 13 having the spray line 7 having the above configuration will be described below. First, as a process before loading, when the tank 1 is in an empty state at room temperature, the LNG supply mechanism is operated to introduce LNG into the main spray line 8 and the ceiling spray line 9 to remove LNG. It is made to spray in the tank 1 from the nozzles 11, 11, .... Therefore, LNG vapor is generated from the atomized LNG, and the wall portion 5 of the tank 1 is cooled through this vapor to perform pre-cooling. While the LNG stored in the tank 1 is -162 ° C, when the wall 5 of the tank 1 is cooled to about -110 ° C, the LNG supply mechanism is stopped to complete the pre-cooling, and the LNG Start loading.

Next, when the LNG is transported to the destination and the cargo LNG is discharged from the tank 1, the tank 1 is not completely empty and a small amount of LNG is left at the bottom of the tank 1. Let it stay. In this state, when LNG is stored again in the tank 1, the spray pump 12 is operated to collect the residual LNG in the LNG circulation mechanism, and the LNG circulation mechanism is activated to collect the residual LNG in the main spray line. 8. It is introduced into the ceiling spray line 9 and sprayed into the tank 1 from the nozzles 11, 11, .... Then, the wall portion 5 of the tank 1 is cooled and pre-cooled by the same operation as described above, and LNG can be accommodated in the tank 1.

In the tank cooling device 13 having the above structure, a large amount of LNG is sprayed from the main spray line 8 having a large diameter, and atomized LNG drops 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 in the course of time. Further, since the LNG sprayed from the ceiling spray line 9 falls from above the main spray line 8, it is difficult to cool the LNG from the main spray line 8 at the upper portion of the tank 1, especially at the ceiling plate 3 and its peripheral portion. To be done. Therefore, according to the configuration of the spray line 7, the entire wall portion 5 of the tank 1 can be efficiently cooled.

Further, since the angle of the nozzles 11, 11, ... Is set so that the sprayed LNG does not come into direct contact with the wall portion 5 of the tank 1, the wall portion 5 of the tank 1 depends on the LNG. And is indirectly cooled via the vapor in the tank 1, and this cooling device can reliably avoid damage to the wall 5 of the tank 1 due to thermal stress.

Further, when the LNG is stored in the tank 1 again after the LNG transportation is completed, the tank cooling device 13 circulates the residual LNG in the tank 1 by the LNG circulation mechanism, Since the precooling is performed, it is not necessary to introduce new LNG for precooling except when the tank 1 is completely empty, and the precooling can be performed efficiently and promptly.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned 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 to the specific configuration of each part.

[0023]

[Effect of device]

 As described in detail above, 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 arranged in the space above the tank, and the tank ceiling plate Since the liquefied gas is sprayed from the sub-liquefied gas flow pipe disposed in the space between the main liquefied gas flow pipe and the main liquefied gas flow pipe, the tank below the main liquefied gas flow pipe is liquefied gas from the main liquefied gas flow pipe. The wall part is cooled, and the liquefied gas from the sub-liquefied gas flow pipe cools the ceiling plate of the tank and its peripheral part. Therefore, the tank cooling device of the present invention can efficiently and reliably precool the tank.

[Brief description of 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]

 1 Tank 3 Ceiling Board 8 Main Spray Line (Main Liquefied Gas Distribution Pipe) 9 Ceiling Spray Line (Sub Liquefied Gas Distribution Pipe) 11 Nozzle 13 Tank Cooling Device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akito Shinda 11-1 Kitahamacho, Chita City, Aichi Prefecture Ishikawajima Harima Heavy Industry Co., Ltd. Aichi Factory

Claims (1)

[Scope of utility model registration request] 1. A tank cooling device for a liquefied gas carrier that introduces liquefied gas into a liquefied gas storage tank stored in a hull to precool the tank, which is horizontal in a space above the tank. The main liquefied gas flow pipe provided with a nozzle that is disposed so as to extend in the direction and sprays the liquefied gas introduced into the pipe by diffusing it outward, the ceiling plate of the tank, and the main liquefied gas flow pipe. A sub-liquefied gas flow pipe provided with a nozzle that is disposed so as to extend in the horizontal direction in the space portion between and diffuses and sprays the liquefied gas introduced into the pipe into the space portion adjacent to the ceiling plate. A tank cooling device for a liquefied gas carrier, comprising: