JP2001124294A - Boil-off gas(bog) cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boil-off gas cooling system whose required whole length is shortened for accelerating complete evaporation of an LNG droplet directly ejected to boil-off gas. SOLUTION: This boil-off gas cooling system for cooling heated boil-off gas in a process to compress boil-off gas(BOG) is equipped with a cooler 30 which comprises a cylindrical body, makes boil-off gas flow into form an inflow opening 10 at its one end and flow out from an outflow opening 11 at its other end, a spray nozzle 12 which is arranged in the cooler and ejects the LNG droplet to the inside of a boil-off gas flow directly and from one end side of the cooler toward the other end side thereof, and a throttle plate 13 which is arranged opposite to the injection surface of the spray nozzle, increases a flow speed by restricting the running boil-off gas flow in the cooler, to change its downstream side into a gas pressure reducing territory where pressure is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boil-off gas cooling device that cools a heated boil-off gas in a process of compressing the boil-off gas (BOG).

[0002]

2. Description of the Related Art Boil-off gas (B) generated from LNG
OG) is compressed, mixed with vaporized LNG, and supplied as, for example, fuel for power generation. Here, a system for cooling a boil-off gas, which is heated by compression, is constructed.

That is, a pre-cooler, a compressor, and an after-cooler are provided along a boil-off gas flow passage, and a pump for supplying cooling water to each of the coolers is provided. The boil-off gas is cooled by a pre-cooler using cooling water, and then pressurized and compressed by a compressor. The boil-off gas that has been heated to a high temperature after being compressed is cooled using cooling water by an aftercooler, and then guided to a gas supply line of LNG. The cooling water whose temperature has risen is re-cooled by heat exchange with seawater or outside air, and is recycled.

[0004] As described above, the conventional boil-off gas cooling system requires water supply equipment and pump power to use cooling water for cooling in the precooler and the aftercooler.
Equipment costs are enormous. Also, when using seawater to recool the cooling water, the heat transfer surface is easily contaminated by marine organisms,
Maintenance is required to maintain the heat transfer performance, which increases running costs. Since the gas is cooled by the cooling water, the cooling target temperature cannot be lower than the cooling water temperature, and there is a restriction in setting the target temperature range.

Accordingly, the present applicant has disclosed in Japanese Patent Application Laid-Open No. H11-828.
No. 93 has developed and filed a compressed gas cooling system. This is shown in FIG. 9 and will be briefly described below.

The boil-off gas is cooled by guiding a part of LNG sent from the high-pressure gas supply pump 5 to the LNG vaporizer 4 into the bure cooler 1 and directly injecting it into the boil-off gas flowing in the cooler.

[0007] Thereafter, the boil-off gas which has been guided to the compressor 2 and is pressurized and compressed to have a high temperature is supplied to the aftercooler 3.
Is cooled by directly injecting a part of LNG sent from the gas sending high pressure pump 5. After LNG is gasified and mixed with the boil-off gas, the LNG is sent to a gas supply line together with the gas vaporized by the LNG vaporizer 4 and is used as fuel for power generation.

By employing such a cooling system, cooling water is not required, and water supply equipment such as a pump and the like can be cooled without requiring maintenance, and various effective conditions such as reduction in power of a compressor can be obtained. It became so.

[0009]

On the other hand, there still remains a problem to be solved. One of the problems is that the LNG droplets injected in each cooler do not completely evaporate depending on the conditions, and remain in a liquid state. There is so-called drainage. For example, the same applies to the case where drainage is generated at the time of start-up or termination of operation, or when emergency stop is performed for some reason.

When the operation is started or continued with the drain or the droplet remaining in the cooler, the drain or the droplet has an extremely low temperature and flows into the downstream side or the upstream side of the cooling equipment. This cooling facility must be constructed with low-temperature materials such as stainless steel,
It is conceivable that equipment used at room temperature may suffer equipment damage.

Therefore, in order to completely evaporate the LNG droplets in the cooler under any change in the situation, the length of the cooler is set to be longer so as to have a margin. Therefore, the required length of the cooling facility in the gas flow direction is extremely long, and the facility must be enlarged.

The present invention has been made on the basis of the above circumstances, and a first object of the present invention is to make it necessary to promote the complete evaporation of LNG droplets directly injected into a boil-off gas. It is an object of the present invention to provide a boil-off gas cooling device that can reduce equipment costs by shortening the entire length of the device.

[0013] A second object is to use all of the generated drain as fuel without discarding it despite the complete evaporation of LNG droplets directly injected into the boil-off gas. It is an object of the present invention to provide a boil-off gas cooling device.

[0014]

According to the present invention, there is provided a boil-off for cooling a boil-off gas heated in a process of compressing a boil-off gas (BOG). In a gas cooling device, a cooler that is formed of a cylindrical body, flows in boil-off gas whose temperature is increased from an inlet provided at one end thereof, and flows out from an outlet provided at the other end. L in the flow and in the gas flow direction
Injection means for injecting NG droplets, and a flow of boil-off gas provided in opposition to the injection surface of the injection means and being circulated in the cooler is increased to increase the flow velocity, thereby lowering the pressure on the downstream side to reduce L
Throttle means for setting a gas decompression region for promoting the evaporation of NG.

In order to solve the above problems and achieve the second object, the present invention provides a boil-off gas (BO)
G) In a boil-off gas cooling device for cooling a boil-off gas heated in a process of compressing, a heated boil-off gas is made to flow from an inlet provided at one end of a cylindrical body, and an outlet provided at the other end. A cooling device for discharging LNG droplets in the flow of the boil-off gas and in the gas flow direction, and provided inside the cooling device or outside the cooling device. A drain collection part for collecting the drain which is LNG remaining in a liquid state without completely evaporating LNG droplets, and a drain collection part provided in the above-mentioned cooler or at the inlet side pipe, and the flow rate of the boil-off gas is reduced by Means for reducing the pressure on the downstream side to reduce the pressure on the downstream side, and communicating the gas pressure reduction area on the downstream side of the throttle means with the drain collecting section to eject by a differential pressure. And characterized by including a drain processing circuit for re-spraying leads to gas pressure reduction region of the throttle means downstream drain to Atsumaritamari the drain current reservoir by the effect.

In order to solve the above problems and achieve the second object, the present invention provides a boil-off gas (BO)
G) In a boil-off gas cooling device for cooling a boil-off gas heated in a process of compressing, a boil-off gas comprising a cylindrical body, the heated boil-off gas flows through an inlet provided at one end, and an outlet provided at the other end. A cooling device for discharging LNG droplets in the flow of the boil-off gas and in the gas flow direction, and provided inside the cooling device or outside the cooling device. A drain collection unit for collecting a drain, which is LNG remaining in a liquid state without completely evaporating LNG droplets;
A heating means is provided on an outer surface of the drain collecting part, and heats the drain of the drain collecting part to evaporate it into gas.

According to the first aspect of the present invention, there is provided means for solving the above-mentioned problems, and the boil-off gas is efficiently cooled by completely evaporating the LNG droplets directly injected into the flow of the boil-off gas. The required length of the cooler in the gas flow direction can be reduced.

According to the second and third aspects of the present invention,
Although the LNG droplets directly injected into the boil-off gas are completely evaporated, the generated drain is effectively used as fuel without being discarded.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment, in which a compressor 2 and an aftercooler 3 are communicated via a pipe Pa, and the aftercooler 3 described above with reference to FIG. Of the cooler 30.
In addition, there is no problem even when the cooler 30 is applied to the precooler 1 disposed downstream of the compressor 2.

The above-mentioned cooler 30 of the type in which the cylinder is placed horizontally
In the figure, an inflow port 10 is provided at the left end of the figure, and communicates with the compressor 2 via a pipe Pa. An outlet 11 is provided at the right end of the cooler 30 in the drawing, and a pipe P is connected to a gas sending line (not shown here) through which vaporized LNG is sent.
b.

A spray nozzle 12 serving as an injection means is disposed inside the cooler 30. This spray nozzle 12
Is formed, for example, in a full cone shape, and the injection surface a is directed toward the outlet 11 at the right end in the figure, and is injected in the same direction as the flow of the boil-off gas in the cooler 30.

A pipe Pc connected to the spray nozzle 12 is connected to a gas pressure high-pressure pump 5 for LNG described above with reference to FIG.
And the LNG vaporizer 4.

That is, a part of the LNG sent from the gas supply high-pressure pump 5 is diverted to the pipe Pc, the flow rate is controlled by a flow control valve, and the flow is guided to the spray nozzle 12, from which LNG droplets are jetted. It has become.

Therefore, although one spray nozzle 12 is shown in FIG. 1, depending on conditions such as the flow rate of the boil-off gas, the injection amount of the LNG droplet with respect to the pressure and the temperature, and the setting of the droplet particle size, You may need more than one.

An aperture plate 13 serving as aperture means is disposed opposite to the spray surface a of the spray nozzle 12. The peripheral edge of the aperture plate 13 is in close contact with the inner peripheral wall of the cooler 3 so as to partition the inside of the cooler 3 left and right, so that there is no leakage. A throttle hole c having substantially the same diameter as that of the spray nozzle is formed only at a portion facing the spray nozzle ejection surface a.

The high-pressure and high-temperature boil-off gas flowing from the inlet 10 of the cooler 30 collides with the throttle plate 13 and passes through the throttle hole c while flowing out of the outlet 11. At this time, the LNG droplet ejected from the spray nozzle 12 also passes through the throttle hole c.

A boil-off gas cooling device constructed as described above, wherein high-pressure and high-temperature boil-off gas derived from the compressor 2 flows through the inlet 10 of the cooler 30 and is throttled on the way. It collides with the plate 13 and passes through the throttle hole c in a concentrated manner.

The flow rate of the boil-off gas passing through the throttle hole c rises at a stroke, and the pressure decreases when the gas leaves the throttle hole c. In other words, the downstream portion of the throttle plate 13 is in a gas decompression region, and is under an environmental condition in which droplets are apt to evaporate with a decrease in atmospheric pressure.

On the other hand, LNG droplets adjusted to optimal conditions are ejected from the spray nozzle 12 and directed toward the gas pressure reduction region of the boil-off gas formed downstream of the throttle plate 13 via the throttle hole c.

Here, the saturation temperature corresponding to the pressure of the LNG is lowered to promote the evaporation, and the boil-off gas is cooled efficiently. As the LNG droplets evaporate completely, the boil-off gas cools down, flows through the cooler 3 and is drawn out of the outlet 11.

By adopting such a configuration, the cooler 30 of the present invention can shorten the required length in the gas flow direction as compared with the after-cooler 3 of FIG. While preventing the LNG droplets injected into the cooler 30 from being mixed into the gas feed line.

FIG. 2 shows a modification of the first embodiment. The cooler 30A is composed of a vertical cylindrical body, and an inlet 10 is provided on a lower side, and an outlet 1 is provided on an upper side.
1 is provided. Spray nozzle 12 for injecting LNG
Is provided on the upper side near the inflow port 10 and directs the ejection surface a upward. The aperture plate 13 is provided near the upper part of the spray nozzle ejection surface a and vertically partitions the inside of the cooler 30A,
A throttle hole c is opened facing the nozzle ejection surface a.

Even with such a configuration, the flow rate of the boil-off gas passing through the throttle hole c is increased to lower the pressure in the vicinity of the upper portion, which is the downstream portion of the throttle plate 13, to form a gas pressure reduction region, and the spray nozzle 12 Complete evaporation of the LNG droplets ejected from the nozzle. Therefore, the cooling efficiency for the boil-off gas is increased, and the required length of the cooling equipment in the gas flow direction can be reduced.

It is conceivable that some of the LNG droplets blown up from the spray nozzle 12 adhere to the inner peripheral wall of the cooler 30A and flow down without evaporating due to various conditions. The LNG droplets flowing down are blocked by the diaphragm plate 13 and accumulated on the upper surface side.
The boil-off gas passes through the throttle hole c at a high flow rate, so that the LNG droplets are prevented from flowing down and forming a drain.

FIG. 3 shows a second embodiment. LNG
The cooling device 30B for directly injecting the droplets into the boil-off gas for cooling is provided, and the cooling effect of the boil-off gas is improved. Of course, depending on various conditions, the injected LNG droplets are completely evaporated. It is supposed that the droplets will not be able to be reached, remain as smaller-diameter droplets, and will aggregate and enlarge, eventually turning into drain.

In the drawing of the cooler 30B, an inlet 10 is provided on the lower side, and an outlet 11 is provided on the upper side. In particular, the pipe Pa connected to the inflow port 10 is formed in an L-shape, and a throttle plate 13 having a throttle hole c at this horizontal portion.
Is provided, and the inside of the pipe Pa is divided into right and left.

The pipe Pa connected to the inflow port 10
Is provided with a drain collecting portion 14 formed of a bottomed cylindrical body extending downward. Since the drain collecting portion 14 is located immediately below the cooler 30B, the LNG droplets remaining without being completely evaporated, that is, the drain, are discharged from the cooler 3B.
Flow down from 0B and collect.

A pipe 15 forming a drain processing circuit is connected between the bottom of the drain collecting section 14 and the pipe Pa downstream of the throttle plate 13. That is, one end of the drain treatment pipe 15 is connected to the bottom of the drain collection part 14, and the other end is connected to the vicinity of a downstream side of the throttle plate 13 in the pipe. Note that the other end of the drain processing pipe 15 may be raised up to the lower end position of the throttle hole c opening in the throttle plate 13.

In the boil-off gas cooling device constructed as described above, the high-pressure and high-temperature boil-off gas derived from the compressor 2 collides with the throttle plate 13 while flowing through the pipe Pa, and the throttle hole c Concentrate on passing through. Accordingly, the flow velocity increases through the throttle hole c, and the pressure drops when the gas passes through the throttle hole c, so that the downstream portion of the throttle plate 13 is a gas decompression region.

On the other hand, some of the LNG droplets ejected from the spray nozzle (not shown) may not evaporate in the boil-off gas, but may flow down from the cooler 30B as drain and accumulate in the drain accumulating portion 14.

The drain treatment pipe 15 has one end connected to the drain collection part 14 and the other end opened to the gas decompression region on the downstream side of the throttle plate 13. The drain collected in the reservoir 14 is guided to the gas decompression region, and is injected from the opening end in a re-spray state to be gasified.

Therefore, the drain of the drain collecting part 14 can be promptly removed without any power and no running cost is required, and at the same time, the boil-off gas is efficiently cooled before being guided to the cooler 30B. Gain efficiency gains.

FIG. 4 shows a modification of the second embodiment. The cooler 30C is composed of a vertical cylindrical body, and the spray nozzle 12 is provided inside the cooler 30C.
Is provided with a diaphragm plate 13 in which a diaphragm hole c is opened.

Since the cooler 30C is a vertical cylindrical body, a drain collecting portion 14 is formed at the lower end, and one end of a pipe 15 forming a drain processing circuit is connected to the drain collecting portion 14C.
The other end is open near the upper portion, which is a downstream portion of the diaphragm plate 13, but may extend to the side edge position of the diaphragm hole c opened in the diaphragm plate 13.

The drain in the drain collecting section 14 is sucked up through the drain processing pipe 15 and is re-sprayed into gas in a gas decompression region near the upper portion, which is a downstream portion of the throttle plate 13, by an ejector effect due to a differential pressure, and is gasified. It can be cooled by mixing with boil-off gas.

FIG. 5 shows still another modification. The spray nozzle 12 is provided inside the cooler 30 </ b> D formed of a horizontal cylinder. The aperture plate is not shown, but may be provided.

A throttle plate 13 is provided in the middle of a pipe Pa connected to the inlet 10 of the cooler 30D, and one end of a pipe 15 constituting a drain processing circuit is connected to a downstream portion. A drain collecting portion 14 formed of a concave portion is provided near the outlet 11 of the cooler 30D and on the bottom side, and the other end of the drain treatment pipe 15 is connected. Note that one end of the drain processing pipe 15 may be raised up to the lower end position of the peripheral edge of the throttle hole c opening in the throttle plate 13.

Therefore, the drain of the drain collection part 14 is guided to the drain processing pipe 15 and is re-sprayed in the gas decompression region at the downstream side of the throttle plate 13 by the ejector effect due to the differential pressure in the pipe Pa to be gasified.

By gasifying the drain in the pipe Pa, it can be cooled by mixing it with the boil-off gas flowing into the cooler 30D, while the drain is made effective and rapid processing is performed.

Although the cooler 30D is provided with the drain collecting portion 14 which is a concave portion, the present invention is not limited to this.
The entire bottom of the cooler 30D may be used as a drain collecting part, and the pipe 15 constituting the drain processing circuit may be connected to the bottom of the cooler.

FIG. 6 shows still another modification. A cooler 30 </ b> E, which is a horizontal cylinder, has a spray nozzle 12 and a throttle plate 13 provided therein. A drain collecting portion 14 formed of a concave portion is provided near the outlet 11 of the cooler 30E, and one end of a pipe 15 forming a drain processing circuit is connected. The other end of the drain processing pipe 15 is connected to the downstream side of the throttle plate 13, but may be raised to the lower end position of the peripheral edge of the throttle hole c opened in the throttle plate 13.

Therefore, the drain of the drain collecting part 14 is sucked up through the drain processing pipe 15, and is re-sprayed in the gas decompression region on the downstream side of the throttle plate 13 to be gasified by the ejector effect due to the differential pressure.

By gasifying the drain in the cooler 30E, it is mixed with the boil-off gas flowing in the cooler to promote cooling, while the drain is made effective to perform the rapid processing.

Further, the cooler 30E is provided with the drain collecting portion 14 serving as a concave portion, but the present invention is not limited to this.
The entire bottom of the cooler 30E may be formed as a drain collecting part. At this time, one end of the drain treatment pipe 15 is connected to the bottom of the cooler 30E, and the other end is located on the downstream side of the throttle plate 13 at the periphery of the throttle hole c. It will rise to the lower end position.

FIG. 7 shows a third embodiment. LNG
An L-shaped pipe Pa for injecting and guiding the same boil-off gas as described above with reference to FIG.
Are connected to each other, and a drain collecting portion 14 extending in the vertical direction is provided at the bent portion.

An electric heater 16 which is insulated and protected by a heat insulating material as a heating means is attached to the outer surface of the drain collecting section 14. Then, a liquid level gauge (not shown) is provided in the drain collection unit 14, and an energization control signal is sent to the electric heater 16 in a state where the drain at a predetermined water level or higher is collected, so that the drain is heated and evaporated. Has become.

The evaporated drain is gasified, and is cooled
Mix into the boil-off gas sent to F. Therefore,
Processing that effectively uses the generated drain as a high-pressure gas fuel can be performed.

FIG. 8 shows a modification of the third embodiment. The cooler 30G is formed of a horizontal cylinder, and the spray nozzle 12 is provided inside. The aperture plate is not shown, but may be provided.

A drain collecting portion 14 composed of a concave portion is provided in the vicinity of the outlet 11, and an electric heater 16 protected by a heat insulating material as a heating means is mounted on the outer surface of the drain collecting portion 14.
In a state where the drain having a predetermined water level or more is collected, the electric heater 1
6 is energized to heat and drain the drain. The evaporated drain is gasified and can be effectively used as a high-pressure gas fuel.

In this case, if the entire bottom of the cooler 30G is used as the drain collecting portion, the area for mounting the heating means 16 for heating the drain becomes extremely large. is there.

In each of the above-described embodiments and the modifications thereof, the aperture plate 13 having the aperture hole a has been described as the aperture means. However, the invention is not limited to this.
For example, a venturi tube or the like that reliably restricts the flow of gas may be used.

[0062]

As described above, according to the present invention, the flow of the boil-off gas is increased by reducing the flow of the boil-off gas to form a gas decompression region on the downstream side. The effect of promoting complete evaporation, shortening the gas flow direction of the required device, and reducing the equipment cost is achieved.

Further, according to the present invention, although the LNG droplets directly injected into the boil-off gas are completely evaporated, the generated drain is collected and the gas pressure is reduced by the ejector effect. Since the liquid is guided to the area and re-sprayed, or the drain in the drain collection part is heated and evaporated, the drain composed of LNG droplets can be completely and effectively used as fuel without being disposed of. To play.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a part of a boil-off gas cooling device according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a boil-off gas cooling device showing a modification of the embodiment.

FIG. 3 is a schematic configuration diagram of a boil-off gas cooling device and its periphery according to a second embodiment of the present invention.

FIG. 4 is a schematic sectional view of a boil-off gas cooling device, showing a modification of the embodiment.

FIG. 5 is a schematic sectional view of a cooling device for a boil-off gas, showing still another modification of the embodiment.

FIG. 6 is a schematic configuration diagram of a boil-off gas cooling device, showing a further different modification of the embodiment.

FIG. 7 is a schematic configuration diagram of a boil-off gas cooling device and its periphery according to a third embodiment.

FIG. 8 is a schematic sectional view of a cooling device for boil-off gas, showing a modification of the embodiment.

FIG. 9 is a schematic cross-sectional view of a boil-off gas cooling device according to a conventional embodiment of the prior application.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Inlet, 11 ... Outlet, 30-30G ... Cooler, 12 ... Spray nozzle (injection means) a ... Injection surface, 14 ... Drain collection part, 13 ... Throttle plate (throttle means), 15 ... Drain processing Piping (drain processing circuit), 16: Electric heater (heating means).

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Tomotaka Ogawa 25, Shintomi, Futtsu City, Chiba Prefecture Tokyo Electric Power Company Futtsu Thermal Power Plant (72) Inventor Koichi Hokari 25, Shintomi, Futtsu City, Chiba Prefecture Futtsu Corporation Inside the thermal power plant (72) Inventor Hiroyuki Yoshizawa 25 Shintomi, Futtsu-shi, Chiba Tokyo Electric Power Company Futtsu Thermal Power Plant (72) Inventor Hiroshi Une 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Masakazu Okubo 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside Nihon Kokan Co., Ltd. (72) Inventor Sadayuki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo 1-2-1, Nihon Kokan Co., Ltd. Term (reference) 3E073 DC11 DD07

Claims (3)

[Claims] In a boil-off gas cooling apparatus for cooling a heated boil-off gas in a process of compressing the boil-off gas (BOG), the boil-off gas is formed of a cylinder, and the boil-off gas whose temperature is increased from an inflow port provided at one end of the cylinder. A cooler that flows in and flows out of an outlet provided at the other end; and an ejection unit that is disposed in the cooler and ejects LNG droplets in the flow of the boil-off gas and in the gas flow direction. A throttle means provided to face the injection surface of the injection means, reducing the flow of the boil-off gas flowing through the cooler to increase the flow velocity, and setting the downstream side as a gas pressure reduction region in which the pressure is reduced,
A boil-off gas cooling device, comprising: 2. A boil-off gas cooling apparatus for cooling a heated boil-off gas in a process of compressing the boil-off gas (BOG), comprising a cylindrical body, wherein the boil-off gas whose temperature is increased through an inflow port provided at one end thereof. A cooler that flows in and flows out of an outlet provided at the other end; and an ejection unit that is disposed in the cooler and ejects LNG droplets in the flow of the boil-off gas and in the gas flow direction. LNG provided inside or outside the cooler.
And a drain collecting section for collecting the drain which is LNG remaining in a liquid state without completely evaporating the liquid droplets, and provided in the cooler or on the inlet side pipe to reduce the flow rate of the boil-off gas to reduce the flow rate. A throttle means which raises the pressure of the downstream side to reduce the pressure to a gas decompression area; and communicates the gas decompression area downstream of the throttle means with the drain collection section. A drain treatment circuit for guiding the drain collected in the gas to a gas decompression region on the downstream side of the throttling means for re-spraying. 3. A boil-off gas cooling apparatus for cooling a heated boil-off gas in a process of compressing the boil-off gas (BOG), comprising a cylindrical body, the boil-off gas having a heated temperature being supplied from an inlet provided at one end thereof. A cooler that flows in and flows out of an outlet provided at the other end; and an ejection unit that is disposed in the cooler and ejects LNG droplets in the flow of the boil-off gas and in the gas flow direction. LNG provided inside or outside the cooler.
A drain collecting part for collecting the drain, which is LNG remaining in a liquid state without completely evaporating the liquid droplets, and is attached to an outer surface of the drain collecting part. The drain of the drain collecting part is heated and evaporated. A boil-off gas cooling device, comprising: heating means for gasification.