JPH0682035B2 - Low temperature liquefied gas heat storage device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a device for storing cold heat of low temperature liquefied gas such as liquefied natural gas.

2. Description of the Related Art A facility that uses cold heat at a base for storing liquefied natural gas is, for example, a reliquefaction facility that reliquefyes so-called boil-off gas that is constantly generated from the upper part of the tank that stores the liquefied natural gas and returns it to the tank. In addition, there are facilities such as air separation facility, liquefied carbon dioxide production facility and frozen warehouse. In each of these facilities, the amount of cold heat used is almost constant throughout the day. On the other hand, the flow rate of liquefied natural gas used as city gas fluctuates greatly depending on the day and night. Although the amount of liquefied natural gas used is large in the daytime, the amount used at night is small. Therefore, in each of the above-mentioned facilities that utilize the cold heat of liquefied natural gas, there is a problem that the scale and operating rate of these facilities are determined depending on the gas delivery amount at night. In addition, even at satellite bases that store liquefied natural gas in small and medium scales, there is a large fluctuation in the amount of gas delivered during the day and night.Therefore, at such bases, the cold heat of liquefied natural gas is not used effectively, and Has been heat-exchanged with and has been abandoned in vain.

In order to solve such a problem, a configuration for storing cold heat of liquefied natural gas or the like may be simply as shown in FIGS. 6 and 7. FIG. 6 is a longitudinal sectional view of the heat storage device, and FIG. 7 is a section line of FIG.
FIG. 7 is a cross-sectional view seen from VII-VII. Referring to these drawings, a cold storage agent 2 is stored in a container 1, and inside the cold storage agent 2, for example, a finned heat transfer tube 3, made of aluminum,
4 is soaked. Liquefied natural gas (abbreviated as LNG) is vaporized after passing through one heat transfer tube 3 and supplied as city gas. The boil-off gas in the tank that stores the liquefied natural gas passes through the other heat transfer tube 4 as a medium to be cooled,
Thereby, it is cooled, reliquefied, and returned to the tank. Due to the liquefied natural gas flowing in one heat transfer tube 3,
The cold storage agent 2 is cooled to store cold heat, and the cold storage agent 2 cools the boil-off gas that is the medium to be cooled flowing in the other heat transfer tube 4. Therefore, when the flow rate of liquefied natural gas through one heat transfer tube 3 is large,
The cold storage agent 2 is cooled and cold heat is stored. This heat transfer tube 3
When the flow rate of the liquefied natural gas flowing through the heat transfer pipe 4 is zero or small, the heat transfer tube 4 is cooled by the cold heat stored in the cold storage agent 2.
The gas flowing inside will be cooled. Therefore, even if the amount of liquefied natural gas fluctuates greatly, a large amount of continuous cooling of the boil-off gas can always be performed.

Problem to be Solved by the Invention In such a simply conceivable structure shown in FIGS. 6 and 7, the cold storage agent 2 is cooled by the one heat transfer tube 3, and the cooled cold storage agent 2 is used. And the other heat transfer tube 4
Since the boil-off gas flowing inside is cooled, smooth and efficient heat exchange between the liquefied natural gas and the boil-off gas is not performed, and the heat transfer tubes 3 and 4 are particularly spaced apart from each other. At times, the heat exchange efficiency will be significantly reduced.

Further, in such a configuration, the temperature of the boil-off gas, which is the fluid to be cooled, at the outlet of the heat transfer tube 4 is higher than the temperature of the cold storage agent 2. Therefore, it is desirable to cool the fluid to be cooled to a low temperature.

It is an object of the present invention to provide a device that has excellent heat exchange efficiency and that can cool a fluid to be cooled to a sufficiently low temperature to store low temperature liquefied gas.

Means for Solving the Problems The present invention includes a container for storing a cold storage agent, a set of first and second heat exchangers, and a first passage for a low temperature liquefied gas provided at least in an outer peripheral portion, A second passage for the fluid to be cooled provided through the first passage and the heat transfer wall; an inlet portion for the first passage and an outlet portion for the second passage provided at an upper portion of the first heat exchanger; A first connecting pipe that connects the first passages to each other in the lower part of the first heat exchanger and the lower part of the second heat exchanger, and the second passages in the lower part of the first heat exchanger and the lower part of the second heat exchanger A second connecting pipe that connects the first heat exchanger and an outlet portion of the first passage and an inlet portion of the second passage that are provided in an upper portion of the second heat exchanger; It consists of a detachable attachment member that fixes the upper part of each heat exchanger and also functions as a lid of the container, and each heat is stored in the cool storage agent in the container. A heat storage device for low temperature liquefied gas, characterized in that the exchanger is immersed and a lid is attached by a mounting member.

Further, the present invention is characterized in that the regenerator has a freezing point higher than the temperature of the low temperature liquefied gas.

Action According to the present invention, the cool storage agent is stored in the container, and the heat exchanger is immersed in the cool storage agent. A first passage through which a low temperature liquefied gas such as liquefied natural gas is introduced is formed in at least an outer peripheral portion of the heat exchanger. Therefore, the cold storage agent is cooled as the low temperature liquefied gas passes through the first passage.

Since the second passage through which the fluid to be cooled is introduced is formed via the first passage through which the low temperature liquefied gas is introduced and the heat transfer wall, the low temperature liquefied gas is introduced into the first passage as described above. Then, the fluid to be cooled in the second passage is cooled via the heat transfer wall. Therefore, when the low temperature liquefied gas is being guided to the first passage, the fluid to be cooled is cooled to a sufficiently low temperature close to the temperature of the low temperature liquefied gas. Therefore, the heat exchange efficiency can be improved. Also, the upper part of each heat exchanger is fixed to the mounting member that also serves as the lid of the container,
While using this device, it is possible to immerse the heat exchangers in the cold storage agent in the container and cover the lids, and at the time of maintenance work, it is possible to simultaneously remove the heat exchangers together with the mounting member from the container.

Further, in the present invention, the cold storage agent has a freezing point higher than the temperature of the low temperature liquefied gas, and therefore, the cold storage agent receives the cold heat of the low temperature liquefied gas and solidifies to achieve a large heat storage. it can. In addition, the regenerator thus solidified can sufficiently cool the fluid to be cooled with a large heat of fusion.

Embodiment FIG. 1 is a vertical sectional view of a heat storage device 6 according to an embodiment of the present invention. This heat storage device 6 is used to reliquefy the boil-off gas generated from the upper portion of the tank 7 that stores the liquefied natural gas shown in FIG. The boil-off gas is compressed from the upper part of the tank 7 through the pipe 8 by the compressor 9 and guided from the pipe 10 to the heat storage device 6, where the boil-off gas is cooled and liquefied and stored in the liquid drum 12. To be done. The liquefied natural gas in the liquid drum 12 is returned to the tank 7 from the pipe line 13. The liquefied natural gas in the tank 7 is introduced from the pipe 15 to the heat storage device 6 by the pump 14, whereby the boil-off gas is cooled and reliquefied as described above. Liquefied natural gas from the pipe 15 via the heat storage device 6 is guided to the vaporizer 17 from the pipe 16 and vaporized by, for example, seawater. The gas vaporized in the vaporizer 17 is used as city gas from the pipe 18. Therefore, the usage amount is large in the daytime and small at night. Therefore, in the heat storage device 6, the pipes 15, 16
In order to be able to sufficiently liquefy the boil-off gas even if the flow rate of liquefied natural gas fluctuates significantly and decreases, the liquefied natural gas is liquefied at a high flow rate during the daytime. The cold heat of the gas is stored in the heat storage device 6 so that the boil-off gas can be sufficiently cooled and reliquefied even if the flow rate of the liquefied natural gas is small at night.

FIG. 3 is a horizontal sectional view taken along the section line III-III in FIG. A cool storage agent 21 is stored in the right cylindrical container 20. In the cold storage material 21 in this container 20, one set or two sets of heat exchangers 22 (one set or two sets in this embodiment).
The book) is placed in the position of each side of the virtual square in the horizontal plane and immersed.

FIG. 4 is a mutual piping system diagram of these heat exchangers 22a to 22d. Liquefied natural gas from line 15 is the first heat exchanger
It enters into the inlet part of 22d, is guided from the lower part of the first heat exchanger 22d to the lower part of the second heat exchanger 22c through the first connecting pipe 23, and further from the outlet part of the upper part of the second heat exchanger 22c. 24 through the first heat exchanger 22b of the next set to the inlet of the upper part, and from the lower part of the first heat exchanger 22b through the first connecting pipe 25 and the second heat exchanger 22a. It is discharged from the outlet to the pipe 16. The boil-off gas, which is the fluid to be cooled, enters through the conduit 10 from the inlet portion of the upper portion of the second heat exchanger 22a, and then from the second portion to the second portion.
It is guided to the lower part of the first heat exchanger 22b via the connecting pipe 26,
From the outlet of the upper part of the heat exchanger 22b, it is led to the inlet of the upper part of the second heat exchanger 22c of the next set through the pipe 27, and then from the second connecting pipe 28 to the first heat exchanger 22d. The liquefied natural gas, which is guided to the lower part of the cooling machine, liquefied and thus reliquefied, is discharged from the upper outlet of the first heat exchanger 22a to the pipe line 11, and thus the liquefied natural gas and the fluid to be cooled are separated. , Countercurrent heat exchange. The first and second connecting pipes 23, 25, 26, 28 and the pipe lines 24, 28 are curved so as to allow thermal deformation.

FIG. 5 is a horizontal sectional view of the first heat exchangers 22b and 22d, for example, 22d. This heat exchanger 22a is a so-called plate heat exchanger, and has a first portion through which liquefied natural gas flows.
Passages 30a and 30b are formed, and fins 33 and 34 are vertically extended and planted in the heat transfer walls 31 and 32 that form the outermost peripheral portion of the heat exchanger 22a. The first passages 30a, 30b are separated from the second passages 35a, 35b through which the boil-off gas, which is the fluid to be cooled, is guided, via the heat transfer walls 36, 37. The second passages 35a and 35b are connected to the heat transfer wall 3
It is separated from another first passage 30c via 8,39. These heat transfer walls 31, 32, 36, 37, 38, 39 are attached to the mounting member 40.
Fixed by.

The liquefied natural gas from the pipe 15 flows through the first passages 30a, 30b, 30c in parallel and flows from the first connecting pipe 23 to the second heat exchanger 22c. The boil-off gas flows from the second heat exchanger 22c through the second connecting pipe 28 in the second passages 35a and 35b in parallel in the same manner, and then the pipeline 1
Emitted from 1.

Therefore, since the liquefied natural gas is supplied from the pipeline 15, the heat storage walls 31 and 32 and the fins 33 and 34 are used to store the cold storage agent.
21 is cooled, and the boil-off gas in the second passages 35a, 35b is cooled by heat transfer via the heat transfer walls 36, 37, 38, 39. The boil-off gas in the second passages 35a, 35b receives the cold heat from the liquefied natural gas by the heat transfer walls 36, 37, 38, 39 as described above, and therefore has an extremely low temperature close to that of the liquefied natural gas. It is possible to sufficiently cool the boil-off gas to reliquefy.

The second heat exchangers 22a and 22c also have the same configuration as the above-mentioned first heat exchangers 22b and 22d, except that the flow directions of the first passage and the second passage are reversed.

As the cold storage agent 21, ethanol or the like is suitable, and its freezing point is higher than the temperature of liquefied natural gas, for example, -160 ° C, for example, -130 ° C to -90 ° C. Therefore, when the cold storage agent is cooled by the liquefied natural gas, the cold storage agent solidifies, and a large amount of cold heat can be stored by the heat of solidification. The cold storage agent 21 has a boiling point of, for example, 40 ° C.
Above, the vaporization at room temperature is prevented. The above-mentioned regenerator such as ethanol is preferable because it has stability against repeated solidification and melting and has no adverse effect on phase change due to the influence of impurities.

The heat exchangers 22a to 22d are made of a material having a good thermal conductivity, such as aluminum. The container 20 is made of a low temperature steel plate.

The heat exchangers 22a to 22d are easily fixed to the attachment member 42 (see FIG. 1) that also functions as a lid of the container 20 by providing one set or two or more sets with the two as one set. As a result, the container 20 is covered while the device 6 is in use, and the heat exchangers 22a to 22d are
Dip and hold in the cold storage agent 21 in the container 20, and during maintenance and inspection,
The heat exchangers 22a to 22d are collectively attached to the container 20 by the mounting member 42.
It is possible to take it out from, and workability is improved. Further, the connecting pipe does not pass alone in the longitudinal direction in the regenerator 21, and the fins 33, 34 for promoting heat exchange can be uniformly arranged in the container 20.

In addition, liquefied natural gas and boil-off gas that is a fluid to be cooled are introduced in series to these heat exchangers 22a to 22d, and therefore there is a risk of liquefied natural gas and boil-off gas being lopsided as compared with the case of flowing in parallel. Absent. Further, by flowing the liquefied natural gas and the boil-off gas in series in this manner, the surface temperatures of the heat exchangers 22a to 22d are different, and accordingly, when the regenerator is solidified, A ranking will be created. Therefore, the volume change due to solidification can be absorbed from the unsolidified portion in the vertical direction. Therefore, it is possible to prevent unreasonable force from acting on the container 20.

As another embodiment of the present invention, the fluid to be cooled can be used, for example, to condense the Freon gas that drives the Freon turbine, and the Freon turbine can drive the generator to perform cold power generation. it can. As still another embodiment of the present invention, it can also be used for cooling freon to achieve freezing at, for example, about -80 ° C in a cold processing food processing plant such as a frozen warehouse.

Furthermore, in the present invention, liquid nitrogen, liquid oxygen or the like can be used instead of liquefied natural gas.

EFFECTS OF THE INVENTION As described above, according to the present invention, it becomes possible to cool the fluid to be cooled to a temperature very close to the temperature of the low temperature liquefied gas with good heat exchange efficiency. The heat exchangers and the respective heat exchangers can be taken out from the container all at once to improve the workability, and the communication pipe can be improved without increasing the length of the connecting pipe alone in the container. In addition, the cold storage agent has a freezing point higher than the temperature of the low temperature liquefied gas, which makes it possible to store a large amount of cold heat.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is a piping system diagram of a boil-off gas reliquefaction facility using a heat storage device 6, and FIG. 3 is a section line III-III of FIG. FIG. 4 is a horizontal sectional view as seen from FIG.
~ 22d piping system diagram, Fig. 5 is a horizontal sectional view of the first heat exchanger 22d, Fig. 6 is a longitudinal sectional view of a heat storage device that can be simply considered,
FIG. 7 is a sectional view taken along section line VII-VII in FIG. 6 ... Heat storage device, 20 ... Container, 21 ... Regenerator, 22a, 22c ... Second
Heat exchanger, 22b, 22d ... First heat exchanger, 23, 25 ... First connecting pipe, 26, 28 ... Second connecting pipe, 30a, 30b, 30c ... First passage, 31, 3
2,36,37,38,39 ... Heat transfer wall, 33,34 ... Fin, 35a, 35b ... Second passage

Claims (2)

[Claims] 1. A container for storing a cold storage agent, and a set of first and second heat exchangers, comprising: a first passage of low temperature liquefied gas provided at least at an outer peripheral portion; A second passage for the fluid to be cooled provided through the heat wall, an inlet portion of the first passage and an outlet portion of the second passage provided at an upper portion of the first heat exchanger, and a lower portion of the first heat exchanger. And a lower part of the second heat exchanger, a first connecting pipe for connecting the first passages to each other, and a second connecting pipe for connecting the second passages to each other between the lower part of the first heat exchanger and the lower part of the second heat exchanger A tube, at least one set of first and second heat exchangers including an outlet part of the first passage and an inlet part of the second passage provided in an upper part of the second heat exchanger, and an upper part of each heat exchanger And a detachable and attachable mounting member that also functions as a lid of the container. Each heat exchanger is immersed in the cool storage agent in the container, and the mounting portion In the heat storage device of the low-temperature liquefied gas, characterized by a lid. 2. The heat storage device for low temperature liquefied gas according to claim 1, wherein the regenerator has a freezing point higher than the temperature of the low temperature liquefied gas.