KR102610804B1 - Cryogenic fluid storage tank with improved discharge efficiency - Google Patents

Abstract

A cryogenic fluid storage tank with improved discharge efficiency is disclosed. A cryogenic fluid storage tank with improved discharge efficiency according to an embodiment of the present invention includes a storage tank in which cryogenic fluid is stored, and at least one spacer formed at predetermined intervals inside the storage tank to divide the inside of the storage tank into a plurality of areas. A partition wall, one end of which communicates with the lower part of the partition dividing a first region of the plurality of regions and a second region adjacent to the first region, and the other end is formed to be located at an upper part of the second region, At least one transfer pipe formed to allow gas in the first area to be transferred to the second area when the water level in the first area among the plurality of areas falls below the one level, and the storage tank It includes a discharge portion formed at the bottom so that the stored cryogenic fluid can be discharged, wherein the at least one partition has a lower end spaced apart from the inner wall of the storage tank by a predetermined distance so that the plurality of regions communicate with each other, and the cryogenic fluid is stored in the storage tank. When discharged through the discharge unit, the cryogenic fluid may be exhausted sequentially from the starting area located at one side of the storage tank among the plurality of areas.

Description

Cryogenic fluid storage tank with improved discharge efficiency}

The present invention relates to a cryogenic fluid storage tank with improved discharge efficiency, and more specifically, in a storage tank storing cryogenic fluid, a suction end of a pump for discharging the stored cryogenic fluid during the discharge process of the cryogenic fluid, and a cryogenic fluid storage tank storing the cryogenic fluid. It is about a technical idea that suppresses the occurrence of cavitation and enables smooth pumping until the stored cryogenic fluid is exhausted by making the distance at which the surface of the cryogenic fluid stored in the storage tank, which changes due to discharge, become closer as possible.

As the seriousness of energy problems caused by the use of fossil fuels is increasing, research on alternative fuels is actively underway.

Among them, the technological idea of using hydrogen as a fuel is attracting attention as an alternative fuel because it is environmentally friendly and highly efficient. Its application range is wide, not only in hydrogen vehicles that use hydrogen as fuel rather than gasoline or diesel, but also in small devices such as drones. I'm losing.

This hydrogen is supplied and stored in a liquefied state. The liquefied hydrogen is stored in a cryogenic state, and a cryogenic fluid such as liquefied hydrogen is stored in a storage tank, and is supplied to a predetermined supply target (e.g., fuel cell or hydrogen vehicle). etc.) needs to be properly supplied.

In order to supply the cryogenic fluid stored in the storage tank to the supply target, it is necessary to discharge the cryogenic fluid stored in the storage tank.

At this time, the discharge part of the storage tank is equipped with a pump to suck in the stored cryogenic fluid to induce discharge of the cryogenic fluid. For smooth pumping, it is necessary to maintain a pressure higher than the saturated vapor pressure of the cryogenic fluid at the suction end of the pump. . If the required pressure, that is, a pressure higher than the saturated vapor pressure of the cryogenic fluid, is not maintained, the suction head (NPSH) may not be secured, cavitation may occur, and pumping may not be performed.

The higher the suction head, the more subcooling conditions can be obtained for the stored cryogenic fluid. Conventionally, as described above, if the suction head is not secured, the subcooled liquid does not flow into the suction end of the pump, so the liquid is not pumped, and vaporization There is a problem in that the pump idles due to cavitation as the gas flows in.

In a conventional cryogenic fluid storage tank, when the internal pressure of the storage tank is increased in a predetermined manner to secure the suction head, instantaneous supercooling occurs in the cryogenic fluid within the storage tank, but near the surface of the cryogenic fluid, that is, at the gas-liquid interface. In the vicinity, continuous condensation occurs to maintain saturation. Ultimately, there is a problem in that the heat of condensation due to this condensation penetrates into the cryogenic fluid, raising the temperature of the cryogenic fluid, and the possibility of cavitation occurring increases as the cryogenic fluid vaporizes.

Ultimately, when the level of the cryogenic fluid stored in the storage tank drops to a certain extent, there is a problem that the surface of the cryogenic fluid becomes closer to the suction end of the pump, as described above, and the cryogenic fluid may not be discharged smoothly.

Therefore, in the process of discharging the cryogenic fluid, the distance between the suction end of the pump for discharging the stored cryogenic fluid and the surface of the cryogenic fluid stored in the storage tank, which changes due to the discharge of the cryogenic fluid, is approached as long as possible, thereby increasing the amount of stored cryogenic fluid. A technical idea is required to suppress the occurrence of cavitation until exhaustion and enable smooth pumping.

Patent Document 1. Korean Patent Publication (Publication No. 10-2017-0057393, “Reliquefaction Equipment for Boil-Off Gas”)

The problem to be solved by the present invention is to make the suction end of the pump for discharging the stored cryogenic fluid closer to the surface of the cryogenic fluid stored in the storage tank, which changes due to the discharge of the cryogenic fluid, through the structure in the storage tank where the cryogenic fluid is stored. The goal is to provide technical ideas to make the distance possible as long as possible.

The cryogenic fluid storage tank with improved discharge efficiency according to an embodiment of the present invention for solving the above technical problem includes a storage tank in which cryogenic fluid is stored, and a plurality of areas formed inside the storage tank at predetermined intervals to define the interior of the storage tank. at least one partition dividing the plurality of regions, one end of which communicates with the lower part of the partition dividing a first region of the plurality of regions and a second region adjacent to the first region, and the other end of the second region At least one transfer device formed to be located at the top so that when the water level in the first region among the plurality of regions falls below the one level, the gas in the first region can be transported to the second region. It includes a pipe, and a discharge part formed at the lower part of the storage tank to allow the stored cryogenic fluid to be discharged, wherein the at least one partition has a lower end spaced apart from the inner wall of the storage tank by a predetermined distance to form the plurality of regions. When they are in communication and the cryogenic fluid is discharged through the discharge unit, the cryogenic fluid may be exhausted sequentially from the starting region located at one side of the storage tank among the plurality of regions.

In addition, the discharge part is formed to be located below the area located at the other end of the storage tank, and the cryogenic fluid is exhausted from the area furthest from the discharge part among the plurality of areas. can do.

In addition, the cryogenic fluid storage tank with improved discharge efficiency includes a transfer line whose one end is connected to the lower part of the storage tank and the other end connected to the upper part of the starting area, and a vaporizer provided at a predetermined position of the transfer line. It may further include that the cryogenic fluid transferred through the transfer line is vaporized through the vaporizer and injected into the starting area, thereby increasing the pressure inside the storage tank.

According to one embodiment of the present invention, the structure in the storage tank where the cryogenic fluid is stored allows the suction end of the pump for discharging the stored cryogenic fluid to become closer to the surface of the cryogenic fluid stored in the storage tank, which changes due to the discharge of the cryogenic fluid. By making the distance as long as possible, there is an effect of suppressing the occurrence of cavitation and enabling smooth pumping until the stored cryogenic fluid is exhausted.

In order to more fully understand the drawings cited in the detailed description of the present invention, a brief description of each drawing is provided.
Figure 1 shows a schematic configuration of a cryogenic fluid storage tank with improved discharge efficiency according to an embodiment of the present invention.
Figures 2 and 3 are diagrams for explaining the initial state of a cryogenic fluid storage tank with improved discharge efficiency according to an embodiment of the present invention.
Figures 4 and 5 are diagrams for explaining the process of discharging cryogenic fluid from a cryogenic fluid storage tank with improved discharge efficiency according to an embodiment of the present invention.

Since the present invention can be modified in various ways and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all transformations, equivalents, and substitutes included in the spirit and technical scope of the present invention. In describing the present invention, if it is determined that a detailed description of related known technologies may obscure the gist of the present invention, the detailed description will be omitted.

Terms such as first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

In this specification, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are intended to indicate the presence of one or more other It should be understood that this does not exclude in advance the presence or addition of features, numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, the present invention will be described in detail focusing on embodiments of the present invention with reference to the attached drawings. The same reference numerals in each drawing indicate the same member.

Figure 1 shows a schematic configuration of a cryogenic fluid storage tank with improved discharge efficiency according to an embodiment of the present invention.

Referring to FIG. 1, a cryogenic fluid storage tank 1 with improved discharge efficiency according to an embodiment of the present invention includes a storage tank 100 in which cryogenic fluid is stored, and is formed inside the storage tank 100 to store the storage tank ( 100) At least one partition wall (e.g., 110 to 112) dividing the interior into a plurality of areas (e.g., Z1 to Z4), one end of which is a first area (e.g., Z1 to Z4) of the plurality of areas (e.g., Z1 to Z4) For example, Z1) and the lower part of a partition wall (e.g., 110) that separates the first area (e.g., Z1) and the neighboring second area (e.g., Z2), and the other end is connected to the second area (e.g., Z2), and when the water level of the first area (e.g., Z1) among the plurality of areas (e.g., Z1 to Z4) falls below the first level, the first area (e.g., It may include at least one transfer pipe (eg, 120 to 122) formed so that the gas in Z1) can be transferred to the second area (eg, Z2). In addition, the cryogenic fluid storage tank 1 with improved discharge efficiency may further include a discharge portion 130 formed at the lower portion of the storage tank 100 through which the stored cryogenic fluid can be discharged. In one embodiment, the discharge unit 130 includes a pump, sucks the cryogenic fluid stored in the storage tank 100, and transfers the cryogenic fluid to the outside of the storage tank 100 (e.g., transferring the cryogenic fluid to the outside of the storage tank 100). It can be discharged through a pipe, etc.). Of course, depending on the implementation, the discharge unit 130 may not include a pump and may simply be implemented in the form of an discharge port that induces discharge of the cryogenic fluid using gravity. Hereinafter, a case will be described as an example in which the discharge unit 130 includes a pump as described above and is implemented in a form that suctions the cryogenic fluid stored inside the storage tank 100. However, the present invention is not necessarily limited thereto. no.

Meanwhile, the cryogenic fluid may be a liquefied gas in which a predetermined gas is liquefied. Hereinafter, in this specification, the case where the cryogenic fluid is liquefied hydrogen will be described as an example, but the present invention is not necessarily limited thereto. For example, the cryogenic fluid may be a liquefied gas in which various types of gases are liquefied, such as liquefied nitrogen, liquefied helium, liquefied natural gas, etc., and the technical idea of the present invention, which will be described later, can be applied regardless of the type of the cryogenic fluid. This can be easily inferred by an average expert in the technical field to which the present invention pertains.

In addition, according to one embodiment of the present invention, the storage tank 100 is configured to include an inner tank in which the cryogenic fluid is stored, and an outer tank spaced apart from the inner tank by a predetermined distance and formed to surround the inner tank. It can be. In this case, the storage tank 100 may refer to an internal tank in which the cryogenic fluid is stored.

Depending on the implementation, there may be cases where the storage tank consists of a single tank, or it is difficult to physically distinguish between the inner tank and the outer tank. Even in this case, the technical idea of the present invention can be applied in the same way. .

Figure 1 may represent the initial state before discharge of cryogenic fluid begins. At this time, the temperature inside the storage tank 100 is T1, so that the gas part (empty space) and the liquid part (part with the cryogenic fluid) can have uniform temperatures. Also, in the current state, the pressure can also have a uniform pressure of P1.

As described above, a plurality of partition walls (eg, 110 to 112) may be installed in the storage tank 100.

The partition walls (eg, 110 to 112) may be installed so that their lower ends are spaced apart from the inner wall of the storage tank 100 by a predetermined distance, as shown in the drawing. That is, the partition walls (e.g., 110 to 112), excluding the lower portion, may be installed in a predetermined manner (e.g., welding) so that all upper and side portions are tightly fixed to the inner wall of the storage tank 100. The inside of the tank 100 is divided into a plurality of areas (e.g., Z1 to Z4) by the partitions (e.g., 110 to 112), but the lower ends of each partition (e.g., 110 to 112) are connected. It may be in the form.

In this way, the openings of the partitions (e.g., 110 to 112) are located at the lower ends within the storage tank 100, so that the storage tank 100 The occurrence of natural convection circulation internally can be suppressed.

Additionally, transfer pipes (eg, 120 to 122) through which gas can be transferred may be provided at the lower portion of each partition (eg, 110 to 112) as described above.

Hereinafter, for convenience of explanation, it will be assumed that the first area (eg, Z1) among the plurality of areas (eg, Z1 to Z4) is the start area where the cryogenic fluid begins to be exhausted.

The discharge portion 130 may be formed to be located at the lower end of the storage tank 100. In one embodiment, the discharge portion 130 is located from the start area (i.e., the first area (e.g., Z1)). It may be formed to be located at the bottom of the fourth area (eg, Z4), which is the furthest area.

In other words, if the cryogenic fluid starts to run out from one side of the storage tank 100, the discharge part 130 is close to the other side of the storage tank 100 even at the bottom of the storage tank 100. can be located

This is because the cryogenic fluid is sequentially exhausted in the plurality of areas (e.g., Z1 to Z4), and as described above, the condensation heat generated on the surface of the cryogenic fluid does not affect the discharge unit 130. This may be to secure time and distance.

Next, the process of discharging the cryogenic fluid from the storage tank 100 will be described with reference to FIGS. 2 to 5.

2 to 5 are diagrams for explaining the process of discharging cryogenic fluid from a cryogenic fluid storage tank with improved discharge efficiency according to an embodiment of the present invention. Figure 3 and Figure 6, which will be described later, may refer to a graph showing the relationship between pressure and enthalpy for cryogenic fluid.

First, referring to FIGS. 2 and 3, in order to discharge the cryogenic fluid stored in the storage tank 100, it is necessary to increase the pressure inside the storage tank 100.

As a configuration for this, the cryogenic fluid storage tank 1 with improved discharge efficiency is provided from the bottom of the storage tank 100 to the starting area (e.g., first area (e.g., Z1)) of the storage tank 100. It may include a transfer line 200 connected to the top through which cryogenic fluid can be transferred. The transfer line 200 may be provided with a vaporizer 210, and the cryogenic fluid transferred through the transfer line 200 is vaporized while passing through the vaporizer 210 and injected into the upper part of the starting area, The internal pressure of the storage tank 100 can be increased.

At this time, if the initial pressure before the pressure increase is P1 shown in the graph of FIG. 3, the pressure increased through the transfer line 200 and the vaporizer 210 may be P2. As the pressure increases, the cryogenic fluid inside the storage tank 100 changes from the initial A state, that is, a state in which a small amount of gaseous state and the majority of the liquid state are mixed, to B state and becomes supercooled.

At this time, as described above, condensation occurs in the surface of the cryogenic fluid, that is, in a predetermined area near the interface between the gas and liquid portions, and has a relatively high temperature due to the heat of condensation. It may be area ① shown in FIG. 2, and can be represented by point c in the graph of FIG. 3.

The part where the remaining cryogenic fluid is stored, that is, area ②, can maintain the temperature of T1 without any significant change from the initial temperature. Therefore, at the location where the discharge unit 130 is located, the cryogenic fluid is in a liquid state while maintaining supercooling, so pumping for discharge can proceed smoothly.

Thereafter, as shown in FIG. 4, when the cryogenic fluid in the first area (e.g., Z1) is exhausted, the gas in the first area (e.g., Z1) is transferred to the first of the transfer pipes (e.g., 120 to 122). 1 It can be transferred to the upper part of the adjacent second area (eg, Z2) through a transfer pipe (eg, 120). And the cryogenic fluid may be exhausted in the second region (eg, Z2).

As the cryogenic fluid in the starting area, that is, the first area (e.g., Z1), is exhausted and the cryogenic fluid in the second area (e.g., Z2) progresses, the empty space inside the storage tank 100 increases, and the storage tank ( 100) Internal pressure may drop. This decreasing pressure can maintain the pressure P3 required for discharge to the gas introduced through the transfer line 200 and the vaporizer 210 described above.

At this time, area ①, that is, the surface portion of the cryogenic fluid, can represent point d along the specific volume constant curve on the graph of FIG. 6, and area ② where the cryogenic fluid remains is maintained at temperature T1 and supercooled at pressure P3 on the graph of FIG. 6. can be maintained, so pumping for discharge can still proceed smoothly.

As the discharge of the cryogenic fluid continues, as shown in FIG. 5, the cryogenic fluid in the second region (eg, Z2) may be exhausted, and the cryogenic fluid may begin to be exhausted in the third region (eg, Z3). In FIG. 5 , the process for the third area (eg, Z3) may be the same as the second area (eg, Z2) described in FIG. 4 .

Ultimately, according to the technical idea of the present invention, the internal space of the storage tank 100 is divided into a plurality of areas (e.g., Z1 to Z4) using at least one partition (e.g., 110 to 112), and each area (e.g., For example, by allowing the cryogenic fluid to be discharged sequentially from Z1 to Z4), in the process of discharging the cryogenic fluid, compared to a conventional general storage tank, the surface portion of the cryogenic fluid, that is, the portion where condensation heat is generated, is discharged (130). ), it is possible to secure a long distance and time to affect the pump, preventing idling of the pump due to cavitation, which can have the effect of enabling stable discharge and efficient use of cryogenic fluid.

The description of the present invention described above is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. will be. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. For example, each component described as unitary may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. .

Claims (3)

A storage tank where cryogenic fluid is stored;
At least one partition wall formed at predetermined intervals inside the storage tank to divide the inside of the storage tank into a plurality of areas;
One end is in communication with the lower part of the partition wall that separates the first area and the second area adjacent to the first area among the plurality of areas, and the other end is formed to be located above the second area, at least one transfer pipe formed to allow gas in the first area to be transferred to the second area when the water level in the first area among the areas falls below the first level; and
It includes a discharge portion formed at the bottom of the storage tank to allow the stored cryogenic fluid to be discharged,
The at least one partition wall is,
The lower end is spaced apart from the inner wall of the storage tank by a predetermined distance so that the plurality of areas communicate,
When the cryogenic fluid is discharged through the discharge unit, the cryogenic fluid is sequentially exhausted from the start area located at one side of the storage tank among the plurality of areas to the discharge area corresponding to the discharge unit - the plurality of areas In a specific area among the areas, the interface between the cryogenic fluid and the gas descends, and no interface occurs in the area next to the outlet side of the specific area until the interface of the specific area goes below the end of the corresponding transfer pipe. A process in which the gas in the specific area is transferred to the next area through the corresponding transfer pipe when the boundary surface of the specific area goes below the one end of the corresponding transfer pipe and a boundary surface is generated in the next area. A cryogenic fluid storage tank with improved discharge efficiency, characterized in that it can be done sequentially from the start area to the discharge area.
The method of claim 1, wherein the discharge unit,
It is formed to be located at the lower part of the area located at the other end of the storage tank,
A cryogenic fluid storage tank with improved discharge efficiency, characterized in that the cryogenic fluid is exhausted from the area furthest from the discharge unit among the plurality of areas.
The cryogenic fluid storage tank of claim 1, wherein the cryogenic fluid storage tank has improved discharge efficiency,
a transfer line with one end connected to the lower part of the storage tank and the other end connected to the upper part of the starting area; and
It further includes a vaporizer provided at a predetermined position in the transfer line,
A cryogenic fluid storage tank with improved discharge efficiency, characterized in that the cryogenic fluid transported through the transfer line is vaporized through the vaporizer and injected into the starting area, thereby increasing the internal pressure of the storage tank.