Liquid hydrogen fuel supply system using bog pressure

Abstract

The present invention relates to a liquefied hydrogen pump apparatus in a cryogenic storage container equipped with a positive displacement pump using boil-off gas (BOG) pressure and, more specifically, to a liquid hydrogen fuel supply system capable of: operating the positive displacement pump using pressure of natural BOG that is naturally evaporated and vaporized from liquid hydrogen in a hydrogen fuel tank due to external heat inflow and pressure increase; pumping the liquid hydrogen from the hydrogen fuel tank to supply the liquid hydrogen to a hydrogen fuel cell; and minimizing storage loss of the liquid hydrogen by reusing, as fuel for the hydrogen fuel cell, the natural BOG having reduced pressure after operating the positive displacement pump.

Description

Liquid hydrogen fuel supply system using BOG pressure

[0001] The present invention relates to a liquid hydrogen pumping device in a cryogenic storage container equipped with a volumetric pump utilizing BOG pressure, and more specifically, to a liquid hydrogen fuel supply system that can pump liquid hydrogen from a hydrogen fuel storage tank and supply it to a hydrogen fuel cell by operating a volumetric pump using the pressure of natural vaporized gas (Boil Off Gas; BOG) that naturally evaporates and vaporizes from liquid hydrogen in a hydrogen fuel tank due to external heat inflow and pressure rise, and furthermore, can minimize storage loss of liquid hydrogen by reusing the natural vaporized gas with a lowered pressure after operating the volumetric pump as fuel for the hydrogen fuel cell.

[0002] Today, hydrogen has the advantage of being a secondary energy source that causes less environmental pollution during energy generation, can be combined with high-efficiency fuel cells, combustion turbines, and engines, and can be utilized in various industrial fields.

[0003] In terms of hydrogen transportation and storage, hydrogen can be classified into high-pressure gaseous hydrogen supply and liquid hydrogen supply. Since there is a difference of about seven times in transportation costs depending on the form of hydrogen storage when transporting the same weight of hydrogen to a hydrogen fusion station or storage facility using a tank truck, liquid hydrogen is gaining attention as a realistic alternative.

[0004] Liquid hydrogen can be stored in a liquid state in a special cryogenic insulated storage tank by cooling gaseous hydrogen to a cryogenic state (-253°C at atmospheric pressure), and it has a volumetric energy density 865 times that of gaseous hydrogen at the same pressure by reducing the volume of gaseous hydrogen to about 1 / 865.

[0005] Liquid hydrogen allows for large-capacity, or high-density, storage at atmospheric pressure, which can reduce storage costs as well as improve the safety of storage tanks; furthermore, due to its low temperature, it has the advantage of a lower risk of explosion compared to high-pressure gaseous hydrogen.

[0006] However, liquid hydrogen in storage tanks naturally evaporates due to external heat input and pressure drop during transportation or storage, resulting in a loss of storage volume and presenting economic limitations.

[0007] In addition, there is a problem in that if Boil-Off Gas (BOG) generated by natural evaporation and vaporization accumulates within the liquid hydrogen storage tank, the internal pressure rises excessively, and in severe cases, there is a significant risk of liquid hydrogen leakage accidents due to damage and breakage of the storage tank.

[0008] Furthermore, if liquid hydrogen storage tanks fail to handle hydrogen that evaporates and vaporizes due to external heat, a Boiling Liquid Expanding Vapor Explosion (BLEVE) phenomenon may occur.

[0009] Meanwhile, since the inside of the liquid hydrogen storage tank maintains a pressure of about 5 to 6 bar and the inlet side of the fuel cell accepts a pressure of about 15 to 16 bar, in order to use liquid hydrogen as fuel for the fuel cell, a supply pump must be installed in the liquid hydrogen tank to increase the supply pressure to about 15 to 16 bar and supply it to the fuel cell through the fuel supply pipe (discharge line).

[0010] It is stated that the background technology or prior art described herein refers to information possessed by the inventor or acquired during the process of deriving and completing the present invention, and is specified merely to aid in understanding the technical significance of the present invention and to be useful for prior art search and examination, and does not mean technology that was generally known and widely used in the technical field to which the invention belongs prior to the filing of the present invention.

[0011] Accordingly, the inventors of the present invention, taking into account the aforementioned matters comprehensively and with the idea of ​​solving the technical limitations and problems of existing liquid hydrogen fuel supply systems, have devised the present invention as a result of continuous research and strenuous efforts to develop a liquid hydrogen fuel supply system with a new structure that minimizes storage loss of liquid hydrogen by utilizing the pressure of Boil Off Gas (BOG), which is naturally evaporated and vaporized from liquid hydrogen in a hydrogen fuel tank due to external heat input and pressure increase, to operate a positive displacement pump, thereby pumping liquid hydrogen from the hydrogen fuel tank and supplying it to a hydrogen fuel cell, and reusing the Boil Off Gas with reduced pressure after operating the positive displacement pump as fuel for the hydrogen fuel cell.

[0012] Therefore, the technical problem and objective of the present invention is to provide a liquid hydrogen fuel supply system capable of operating a positive displacement pump by utilizing the pressure of natural vaporized gas generated by the evaporation and vaporization of liquid hydrogen within a hydrogen fuel tank.

[0013] Another technical problem and objective of the present invention is to provide a liquid hydrogen fuel supply system capable of minimizing storage loss of liquid hydrogen.

[0014] The technical problems and objectives that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems and objectives will be clearly understood by those skilled in the art from the description below.

[0015] Specific means according to the implementation of the present invention for effectively achieving a specific technical purpose while embodying a new concept for solving the technical problem of the present invention as described above include: a positive displacement pump installed in the middle of a fuel supply line connecting a hydrogen fuel tank and a fuel cell, wherein a plunger reciprocates within a cylinder by means of the pressure of the naturally vaporized gas evaporated and vaporized from the liquid hydrogen in the hydrogen fuel tank and the elastic restoring force of a spring mounted between the cylinder and the plunger, and draws in the liquid hydrogen in the hydrogen fuel tank according to the opening and closing of first and second check valves, and pressurizes and pumps it to the fuel cell through the fuel supply line (discharge line); a pressure regulator installed in the middle of a BOG line discharging the naturally vaporized gas evaporated and vaporized from the liquid hydrogen in the hydrogen fuel tank, which regulates the pressure of the naturally vaporized gas and supplies it to the positive displacement pump; and a device connected to the hydrogen fuel tank and the BOG line, wherein the pressure of the naturally vaporized gas regulated through the pressure regulator is supplied into the cylinder by opening and closing. A liquid hydrogen fuel supply system is presented, characterized by employing: a first valve formed in a valve block for control; a second valve formed in a valve block connected to a fuel cell unreacted hydrogen gas line and controlling the release of naturally vaporized gas within a cylinder through the unreacted hydrogen gas line by opening and closing; a first touch switch that detects when the plunger within the cylinder is at top dead center and opens the passage of naturally vaporized gas within the first valve communicating with the cylinder and closes the passage of naturally vaporized gas within the second valve communicating with the cylinder; and a second touch switch that detects when the plunger within the cylinder is at bottom dead center and closes the passage of naturally vaporized gas within the first valve communicating with the cylinder and opens the passage of naturally vaporized gas within the second valve communicating with the cylinder.

[0016] Thus, the present invention can pump liquid hydrogen from the hydrogen fuel tank and supply it to the hydrogen fuel cell by operating a positive displacement pump using the pressure of the natural vaporization gas (Boil Off Gas; BOG) that is naturally evaporated and vaporized from the liquid hydrogen in the hydrogen fuel tank due to external heat input and pressure drop.

[0017] In addition, the storage loss of liquid hydrogen can be minimized by reusing the naturally vaporized gas with reduced pressure after operating the positive displacement pump as fuel for the hydrogen fuel cell.

[0018] In addition, in a preferred embodiment of the present invention, the first valve is connected to the fuel cell unreacted hydrogen gas line, and when the passage of natural vaporized gas within the first valve communicating with the cylinder is closed, the natural vaporized gas flowing into the BOG line can be discharged into the unreacted hydrogen gas line.

[0019] In addition, a preferred embodiment of the present invention is configured to further include a backflow prevention valve installed in the middle of the unreacted hydrogen gas line to prevent the natural vaporized gas released within the first and second valves from flowing back, thereby allowing the overpressure natural vaporized gas within the first and second valves to flow stably toward the fuel cell through the unreacted hydrogen gas line.

[0020] According to an embodiment implementing a technical concept on which a unique solution means is based to solve the technical problem of the present invention, a positive displacement pump can be operated using the pressure of naturally vaporized gas that has evaporated and vaporized from liquid hydrogen in a hydrogen fuel tank due to external heat inflow and pressure drop.

[0021] Therefore, liquid hydrogen can be pumped from a hydrogen fuel tank and supplied to a hydrogen fuel cell without external input, which reduces energy consumption caused by external power input, enables compactness, and minimizes heat leakage.

[0022] In addition, the naturally vaporized gas with reduced pressure after operating the positive displacement pump can be reused as fuel for the hydrogen fuel cell.

[0023] Therefore, by eliminating or minimizing the input of additional energy sources to pressurize the liquid hydrogen stored in the storage tank to meet the fuel cell input conditions, it is possible to gain an advantage in system operating costs. Furthermore, by minimizing storage losses due to natural vaporization and preventing pressure buildup inside the storage tank, economic feasibility can be secured through the simplification and compactness of equipment required for the safe storage of liquid hydrogen, as well as reductions in energy, maintenance, and equipment costs.

[0024] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims.

[0025] FIG. 1 is a schematic diagram showing a liquid hydrogen fuel supply system according to an embodiment of the present invention.

[0026] FIG. 2 is a schematic diagram showing the suction operation state of a positive displacement pump constituting a liquid hydrogen fuel supply system according to an embodiment of the present invention.

[0027] FIG. 3 is a schematic diagram showing the discharge operation state of a positive displacement pump constituting a liquid hydrogen fuel supply system according to an embodiment of the present invention.

[0028] Figure 4 is a color-coded figure showing the state before spring compression in a positive displacement pump constituting a liquid hydrogen fuel supply system according to an embodiment of the present invention.

[0029] Figure 5 is a color-coded illustration of the operation in a spring compression state of a positive displacement pump constituting a liquid hydrogen fuel supply system according to an embodiment of the present invention.

[0030] Figure 6 is a color-coded figure showing the state before piston movement in a positive displacement pump constituting a liquid hydrogen fuel supply system according to another embodiment of the present invention.

[0031] Figure 7 is a color-coded figure showing the state after piston movement in a positive displacement pump constituting a liquid hydrogen fuel supply system according to another embodiment of the present invention.

[0032] Hereinafter, embodiments according to the present invention will be described in more detail with reference to the attached drawings.

[0033] Prior to this, it is specified that the terms described below are defined in consideration of their functions in the present invention, and should be interpreted in accordance with the concept consistent with the technical spirit of the present invention and the meaning commonly accepted or recognized in the relevant technical field.

[0034] In addition, if it is determined that a detailed description of known functions or configurations related to the present invention could obscure the essence of the present invention, such detailed description is omitted.

[0035] The drawings attached herein are illustrated with exaggerated or simplified portions for the purpose of explaining the configuration and operation of the technology, as well as for ease of understanding and clarity; it should be noted that each component does not exactly correspond to its actual size and shape.

[0036] In addition, the term "and / or" in this specification means a combination of multiple related described items or includes any of the multiple related described items, and when a part is said to include a certain component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0037] In other words, terms such as "comprising" and "having" as set forth in this specification mean that there is a feature, number, step, process, operation, component, part, or combination thereof, and should be understood as not excluding the existence or addition of one or more other features, numbers, steps, processes, operations, components, parts, or combinations thereof.

[0038] Meanwhile, the terms "part" and "unit" used in the present invention refer to a unit or module form that performs a role in processing at least one intended function or a certain operation in a device or system, and this can be implemented through means such as hardware, software, or a combination of hardware and software, or a device or assembly capable of performing independent operations.

[0039] Furthermore, terms such as top, bottom, upper surface, lower surface, or upper, lower, upper side, lower side, front / rear, left / right, etc. used in the present invention are used for convenience to distinguish relative positions or explain directions of movement for each component. For example, the upper part of a drawing may be named or referred to as the upper part and the lower part as the lower part, and the length direction may be named or referred to as the front / rear direction and the width direction as the left / right direction.

[0040] In addition, terms such as "first," "second," etc. used in the present invention may be used to describe various components. That is, terms such as "first," "second," etc. may be used solely for the purpose of distinguishing one component from another.

[0041] [Example 1]

[0042] [Best mode for carrying out the invention]

[0043] A liquid hydrogen fuel supply system according to an embodiment of the present invention is configured to include a positive displacement pump (10), a pressure regulator (20), a valve block (30)(40) forming a first and second valve, and a first and second touch switch (50)(60), as shown in FIGS. 1 to 5.

[0044] A positive displacement pump (10) is installed in the middle of the line of the fuel supply line (DL) connecting the hydrogen fuel tank (T) and the hydrogen fuel cell.

[0045] That is, the positive displacement pump (10) sucks in liquid hydrogen (LH2) from the hydrogen fuel tank (T) through the fuel supply line (DL), increases the pressure by applying pressure, and then supplies it to the hydrogen fuel cell through the fuel supply line (DL) and via the vaporizer.

[0046] Specifically, the positive displacement pump (10) reciprocates the plunger (11) inside the cylinder (12) by means of the pressure of the natural vaporized gas (BOG) evaporated and vaporized from the liquid hydrogen (LH2) inside the hydrogen fuel tank (T) and the elastic restoring force of the spring (13) mounted between the plunger (11) and the cylinder (12), and sucks in the liquid hydrogen (LH2) inside the hydrogen fuel tank (T) according to the opening and closing of the first and second check valves (CV1) (CV2) installed in the middle of the fuel supply line (DL), and supplies it to the hydrogen fuel cell through the fuel supply line (DL) and vaporizer by applying pressure.

[0047] And the intake port (11a) and the discharge port (11b) of the cylinder (12) are formed in a straight line, and a fuel supply line (DL) is connected to the intake port (11a) and the discharge port (11b).

[0048] That is, the natural vaporized gas (BOG), which is evaporated and vaporized from the liquid hydrogen (LH2) in the hydrogen fuel tank (T) and whose pressure is regulated by the pressure regulator (20), is introduced into the cylinder by the head of the plunger (11). Due to this pressure, the plunger (11) pushes the spring with a force greater than that of the opposite spring, pressurizing the liquid hydrogen (LH2) sucked in through the intake port (12a) of the cylinder (12), and discharges the pressurized liquid hydrogen through the discharge port (12b) to the fuel supply line (DL).

[0049] And the spring (13) has a lower elastic modulus than the force applied by the plunger (11), so as the plunger (11) moves, it is compressed by the pressing force of its head and comes into contact with a mechanical touch switch (or valve) mounted on the spring side. At this time, the push-button type touch switch is activated, switching the BOG inflow / outflow path of the valve block (40), closing the BOG path flowing into the cylinder, and opening the FL path, so that the pressure inside the cylinder is reduced. When the pressing force of the plunger (11) head is released, it is pushed back to its original position by the restoring force of a strong spring.

[0050] Here, it is preferable to use a compression coil spring (13) that accumulates elastic energy when compression deformation occurs due to the applied load, i.e., the force pressing the head of the plunger (11), and generates a force (restoring force) that attempts to return to its original state in opposition to the compression force. However, it is not limited to this, and any material that resists the force attempting to compress, such as elastic rubber, which has the same effect as a coil spring through elastic restoring force, may be used.

[0051] Meanwhile, the hydrogen fuel tank (T) stores a certain amount of cryogenic liquid hydrogen (LH2) supplied from the outside in a sealed storage space inside.

[0052] And the hydrogen fuel tank (T) is composed of a vacuum multilayer insulation system of a double metal container filled with a vacuum insulation layer between the inner and outer tanks to ensure insulation of liquid hydrogen.

[0053] That is, the inner tank is mainly made of stainless steel such as SUS 316 or higher to store cryogenic liquid hydrogen (LH2), the outer tank protects the inner tank, and MLI (Multi Layer Insulation) is installed between the inner tank and the outer tank to maintain an ultra-vacuum, so that cryogenic liquid hydrogen (LH2) can be safely stored.

[0054] In addition, a BOG line (BL) is connected to the hydrogen fuel tank (T) to discharge natural vaporized gas (BOG) that has been evaporated and vaporized from liquid hydrogen (LH2).

[0055] Here, the hydrogen fuel tank (T) may be equipped with a safety valve (not shown) to automatically regulate the internal pressure by discharging the natural vaporized gas (BOG) to the outside when the internal pressure rises due to the natural vaporized gas (BOG) evaporating and vaporizing from the liquid hydrogen (LH2) and exceeds a set value.

[0056] A pressure regulator (20) is installed in the middle of a BOG line (BL) for discharging natural vaporized gas (BOG) that has been evaporated and vaporized from liquid hydrogen (LH2) in a hydrogen fuel tank (T).

[0057] That is, the pressure regulator (20) plays the role of adjusting the pressure of the natural vaporized gas (BOG) generated by natural evaporation and vaporization in the hydrogen fuel tank (T) to about 3 bar, since the pressure is maintained at about 5 to 6 bar, and supplying it to the positive displacement pump (10) through the first valve (30) formed in the valve block.

[0058] The first valve (30) is connected to the hydrogen fuel tank (T) and the BOG line (BL), and is connected to the cylinder (12) of the positive displacement pump (10).

[0059] That is, the first valve (30) opens and closes according to the operation of the first touch switch, controlling the supply of pressure-regulated natural vaporized gas (BOG) into the cylinder (12) through the pressure regulator (20).

[0060] And the first valve (30) is connected to the unreacted hydrogen gas line (FL).

[0061] That is, the first valve (30) is connected to an unreacted hydrogen gas line (FL) in order to discharge the natural gas (BOG) flowing into the BOG line (BL) into the unreacted hydrogen gas line (FL) when the passage of the natural gas (BOG) inside the first valve (30) communicating with the cylinder (12) is closed.

[0062] Meanwhile, a backflow prevention valve (CV3) is installed in the middle of the unreacted hydrogen gas line (FL) to prevent the natural vaporization gas (BOG) released from the first and second valves (30) (40) from flowing back.

[0063] The second valve (40) is connected to the cylinder (12) of the positive displacement pump (10) and is connected to the unreacted hydrogen gas line (FL).

[0064] That is, the second valve (40) controls the release of natural vaporization gas (BOG) in the cylinder (12) through the unreacted hydrogen gas line (FL) according to the operation of the second touch switch.

[0065] The first touch switch (50) is preferably a touch switch and, when the plunger (11) is positioned at the top dead center within the cylinder (12), it comes into contact with the end of the plunger and serves to change the BOG flow path within the valve block.

[0066] That is, the first touch switch (50) opens the passage of natural vaporized gas (BOG) in the first valve (30) communicating with the cylinder (12) and closes the passage of natural vaporized gas (BOG) in the second valve (40) communicating with the cylinder (12) when the head of the plunger (11) reaches a predetermined position within the cylinder (12).

[0067] Here, the first touch switch (50) may be a touch switch that mechanically detects whether the plunger (11) head is in close contact or in contact, thereby opening and closing the electrical contact.

[0068] The second touch switch (60) is preferably a touch switch and, when the plunger (11) is positioned at the bottom dead center within the cylinder (12), it comes into contact with the end of the plunger (11) and serves to change the BOG flow path within the valve block.

[0069] That is, the second touch switch (60) closes the passage of natural vaporized gas (BOG) in the first valve (30) communicating with the cylinder (12) and opens the passage of natural vaporized gas (BOG) in the second valve (40) communicating with the cylinder (12) when the head of the plunger (11) reaches a predetermined position within the cylinder (12).

[0070] Here, the second touch switch (60) may be a touch switch that mechanically detects whether the plunger (11) head is in close contact or in contact, thereby opening and closing the electrical contact.

[0071] [Operating Principle and Function]

[0072] The main operation, operating principle, and function of the liquid hydrogen fuel supply system according to the embodiment of the present invention configured as described above are as follows.

[0073] First, as shown in FIG. 2, the natural vaporized gas (BOG) evaporated and vaporized from the liquid hydrogen (LH2) in the hydrogen fuel tank (T) is discharged through the BOG line (BL) and supplied to the first valve (30).

[0074] In this process, the pressure of the natural vaporized gas is regulated to about 3 bar by the pressure regulator (20) and supplied into the cylinder (12) of the positive displacement pump (10) through the first valve (30).

[0075] And the first touch switch (50) detects when the plunger (11) is positioned at the top dead center within the cylinder (12) and opens the passage of the natural vaporized gas (BOG) in the first valve (30) communicating with the cylinder (12), and at the same time closes the passage of the natural vaporized gas (BOG) in the second valve (40) communicating with the cylinder (12).

[0076] Subsequently, when the passage of the natural vaporized gas (BOG) in the first valve (30) communicating with the cylinder (12) is opened and the passage of the natural vaporized gas (BOG) in the second valve (40) communicating with the cylinder (12) is closed, the pressure of the natural vaporized gas (BOG), which is evaporated and vaporized from the liquid hydrogen (LH2) in the hydrogen fuel tank (T) and whose pressure is regulated by the pressure regulator (20), acts on the head of the plunger (11). Due to this pressure, the plunger (11) moves in the opposite direction to the direction in which the natural vaporized gas (BOG) flows into the cylinder (12), thereby pressurizing the liquid hydrogen (LH2) sucked in through the intake port (12a) of the cylinder (12).

[0077] At this time, the first check valve (CV1) installed in the middle of the fuel supply line (DL) remains closed to prevent backflow of natural vaporization gas (BOG), and the second check valve (CV2) opens due to the pressure of liquid hydrogen (LH2), so the liquid hydrogen (LH2) inside the cylinder (12) is naturally discharged into the fuel supply line (DL) through the discharge port (12b).

[0078] In this process, the spring (13) has a lower elastic modulus than the force exerted by the plunger (11), so it is compressed by the pressing force of its head as the plunger (11) moves, and an elastic force is exerted.

[0079] In addition, the second touch switch (60) detects when the plunger (11) is positioned at the bottom dead center within the cylinder (12), closes the passage of the natural vaporized gas (BOG) in the first valve (30) communicating with the cylinder (12), and at the same time, automatically opens the passage of the natural vaporized gas (BOG) in the second valve (40) communicating with the cylinder (12).

[0080] Afterwards, as shown in FIG. 3, when the passage of the natural vaporized gas (BOG) in the first valve (30) communicating with the cylinder (12) is closed and the passage of the natural vaporized gas (BOG) in the second valve (40) communicating with the cylinder (12) is opened, the force pressing the spring (13) of the plunger (11) head is released, and when this happens, the elastic restoring force of the spring (13) acts to push the plunger (11) back to its original position with a strong force.

[0081] In this process, the natural gas vaporization (BOG) in the cylinder (12) and the natural gas vaporization (BOG) in the first valve (30) are discharged toward the hydrogen fuel cell through the unreacted hydrogen gas line (FL).

[0082] In addition, the first check valve (CV1) remains open due to the pressure of the liquid hydrogen (LH2), and the second check valve (CV2) closes as the pressure of the liquid hydrogen (LH2) inside the cylinder (12) decreases. Therefore, the liquid hydrogen (LH2) inside the hydrogen fuel tank (T) is naturally drawn into the cylinder (12) through the intake port (12a) of the cylinder (12) and the fuel supply line (DL).

[0083] In this way, the pressure of the naturally vaporized gas that has been naturally evaporated and vaporized from the liquid hydrogen (LH2) in the hydrogen fuel tank (T) can be used to operate a volumetric pump (10) without power, thereby pumping the liquid hydrogen (LH2) from the hydrogen fuel tank (T) and supplying it to the hydrogen fuel cell.

[0084] In addition, the natural vaporized gas (BOG) with reduced pressure after operating the volumetric pump (10) can be reused as fuel for the hydrogen fuel cell.

[0085]

[0086] [Example 2]

[0087] [Best mode for carrying out the invention]

[0088] A liquid hydrogen fuel supply system according to an embodiment of the present invention is configured to include a positive displacement pump (10), a pressure regulator (20), a valve block (30)(40) forming a first and second valve, and a first and second touch switch (50)(60) installed in a cylinder, as shown in FIGS. 1 to 7.

[0089] That is, a positive displacement pump (10) installed in the middle of a fuel supply line (DL) connecting a hydrogen fuel tank (T) and a fuel cell, wherein a plunger (11) reciprocates within a cylinder (12) by the pressure of natural vaporized gas evaporated and vaporized from the liquid hydrogen (LH2) in the hydrogen fuel tank (T) and sucks in the liquid hydrogen (LH2) in the hydrogen fuel tank (T) according to the opening and closing of first and second check valves (CV1) (CV2) installed in the middle of the fuel supply line (DL), and pressurizes and pumps the liquid hydrogen (LH2) in the hydrogen fuel tank (T) to the fuel cell through the fuel supply line (DL); a pressure regulator (20) installed in the middle of a BOG line (BL) that discharges natural vaporized gas evaporated and vaporized from the liquid hydrogen (LH2) in the hydrogen fuel tank (T), and which regulates the pressure of the natural vaporized gas and supplies it to the positive displacement pump (10); a first valve (30) formed inside; A valve block that controls the supply of natural vaporized gas, whose pressure is regulated through the pressure regulator (20), into the cylinder (12) by opening and closing the flow path through the flow path change of the second valve (40), and controls the release of natural vaporized gas within the cylinder (12) through the unreacted hydrogen gas line (FL); and a first touch switch (50) that detects when the plunger (11) is positioned at the top dead center within the cylinder (12), opens the passage of natural vaporized gas within the first valve (30) communicating with the cylinder (12), and closes the passage of natural vaporized gas within the second valve (40) communicating with the cylinder (12). It can be configured to include a second touch switch (60) that detects when the plunger (12) is positioned at the bottom dead center within the cylinder (12), thereby closing the passage of natural vaporized gas within the first valve (30) communicating with the cylinder (12) and opening the passage of natural vaporized gas within the second valve (40) communicating with the cylinder (12).

[0090] In describing the embodiment 2 through FIGS. 6 and FIGS. 7, parts identical to those in embodiment 1 will be described by applying the same reference numerals with reference to FIGS. 1 to 5.

[0091] However, in order to move the plunger (11) inside the cylinder (12) in both directions rather than by the spring restoring force in Example 1, as shown in FIGS. 6 and 7, the BOG is supplied in both directions through the opening and closing of the first and second valves (30) (40) that form the valve block of the cylinder (12).

[0092] That is, the cylinder (12) and the valve block forming the positive displacement pump (10) are connected, as shown in FIGS. 6 and FIGS. 7.

[0093]

[0094] [Operating Principle and Function]

[0095] The main operation, operating principle, and function of the liquid hydrogen fuel supply system according to the embodiment of the present invention configured as described above are as follows.

[0096] First, as shown in FIG. 6, the natural vaporized gas (BOG) evaporated and vaporized from the liquid hydrogen (LH2) in the hydrogen fuel tank (T) is discharged through the BOG line (BL) and supplied to the first valve (30) located in the cylinder (12) of the positive displacement pump (10).

[0097] In this process, the pressure of the natural vaporized gas is regulated to about 3 bar by the pressure regulator (20) and supplied into the cylinder (12) of the positive displacement pump (10) through the first valve (30).

[0098] And the first touch switch (50) detects when the plunger (11) is positioned at the top dead center within the cylinder (12), opens the passage of the natural vaporized gas (BOG) in the first valve (30) communicating with the cylinder (12), and at the same time automatically closes the passage of the natural vaporized gas (BOG) in the second valve (40) communicating with the cylinder (12).

[0099] Subsequently, when the passage of the natural vaporized gas (BOG) in the first valve (30) communicating with the cylinder (12) is opened and the passage of the natural vaporized gas (BOG) in the second valve (40) communicating with the cylinder (12) is closed, the pressure of the natural vaporized gas (BOG), which is evaporated and vaporized from the liquid hydrogen (LH2) in the hydrogen fuel tank (T) and whose pressure is regulated by the pressure regulator (20), acts on the head of the plunger (11), and due to that pressure, the plunger (11) moves in the opposite direction to the direction in which the natural vaporized gas (BOG) flows into the cylinder (12), thereby pressurizing the liquid hydrogen (LH2) sucked in through the intake port of the cylinder (12).

[0100] At this time, the first check valve (CV1) installed in the middle of the fuel supply line (DL) remains closed to prevent backflow, and the second check valve (CV2) opens due to the pressure of the liquid hydrogen (LH2), so the liquid hydrogen (LH2) inside the cylinder (12) is naturally discharged into the fuel supply line (DL) through the discharge port (12b).

[0101] When the piston forming the plunger (11) moves to the end of one cylinder due to the BOG pressure flowing into the cylinder and touches the first touch switch or the second touch switch (60), the touch switch opens and the BOG that was stagnant in the BOG line flows into the valve block.

[0102] At this time, the first valve (30) and the second valve within the valve block are pushed in opposite directions simultaneously due to the instantaneous inflow of BOG pressure. As a result, the BOG inflow line connected to the other cylinder within the block valve is opened, and a large amount of BOG flows into the other cylinder, causing the plunger (11) to move in the opposite direction again due to the BOG pressure, and the BOG remaining in the opposite cylinder is discharged toward the hydrogen fuel cell through the hydrogen gas line (FL).

[0103] In addition, the first check valve (CV1) remains open due to the pressure of the liquid hydrogen (LH2), and the second check valve (CV2) closes as the pressure of the liquid hydrogen (LH2) inside the cylinder (12) decreases. Therefore, the liquid hydrogen (LH2) inside the hydrogen fuel tank (T) is naturally drawn into the cylinder (12) through the intake port (12a) of the cylinder (12) and the fuel supply line (DL).

[0104] In this way, the pressure of the naturally vaporized gas that has been naturally evaporated and vaporized from the liquid hydrogen (LH2) in the hydrogen fuel tank (T) is used to operate the volumetric pump (10) to pump the liquid hydrogen (LH2) from the hydrogen fuel tank (T) and supply it to the hydrogen fuel cell.

[0105] In addition, the natural vaporized gas (BOG) with reduced pressure after operating the volumetric pump (10) can be reused as fuel for the hydrogen fuel cell.

[0106] Meanwhile, it is obvious to those skilled in the art that the present invention is not limited by the embodiments described above and the attached drawings, and that it can be modified and applied in various ways not exemplified within the scope of the technical concept of the present invention, as well as widely applied by substituting each component and changing to equivalent alternative embodiments.

[0107] Therefore, content related to modifying and applying the technical features of the present invention should be interpreted as being included within the technical concept and scope of the present invention.

[0108] [Explanation of the symbol]

[0109] 10: Positive displacement pump 11: Plunger

[0110] 12: Cylinder 13: Spring

[0111] 20: Pressure regulator 30: First valve

[0112] 40: 2nd valve 50: 1st touch switch

[0113] 60: Second touch switch

[0114] T: Hydrogen fuel tank DL: Fuel supply line

[0115] CV1: 1st check valve CV2: 2nd check valve

[0116] CV3: Check valve BL: BOG line

[0117] FL: Unreacted hydrogen gas line

Claims

1. A positive displacement pump (10) installed in the middle of a fuel supply line (DL) connecting a hydrogen fuel tank (T) and a fuel cell, wherein a plunger (11) reciprocates within a cylinder (12) by means of the pressure of naturally vaporized gas evaporated and vaporized from the liquid hydrogen (LH2) in the hydrogen fuel tank (T) and the elastic restoring force of a spring (13) mounted between the plunger (11) and the cylinder (12), sucks in the liquid hydrogen (LH2) in the hydrogen fuel tank (T) according to the opening and closing of first and second check valves (CV1) (CV2) installed in the middle of the fuel supply line (DL), and pressurizes and pumps the liquid hydrogen (LH2) in the hydrogen fuel tank (T) through the fuel supply line (DL); A pressure regulator (20) installed in the middle of a BOG line (BL) that discharges natural vaporized gas evaporated and vaporized from liquid hydrogen (LH2) in the hydrogen fuel tank (T), and which regulates the pressure of the natural vaporized gas and supplies it to the positive displacement pump (10); A valve block having a first valve (30) formed to control the supply of naturally vaporized gas, whose pressure is regulated through the pressure regulator (20), into the cylinder (12) by opening and closing, connected to the hydrogen fuel tank (T) and the BOG line (BL), and a second valve (40) formed to control the release of naturally vaporized gas into the cylinder (12) through the unreacted hydrogen gas line (FL) by opening and closing; A first touch switch (50) that detects when the plunger (11) is positioned at the top dead center within the cylinder (12), opens the passage of natural vaporized gas within the first valve (30) communicating with the cylinder (12), and closes the passage of natural vaporized gas within the second valve (40) communicating with the cylinder (12); and A second touch switch (60) that detects when the plunger (11) is positioned at the bottom dead center within the cylinder (12), closes the passage of natural vaporized gas within the first valve (30) communicating with the cylinder (12), and opens the passage of natural vaporized gas within the second valve (40) communicating with the cylinder (12); A liquid hydrogen fuel supply system utilizing BOG pressure, comprising 2. In Paragraph 1, A liquid hydrogen fuel supply system using BOG pressure, wherein the unreacted hydrogen gas line (FL) is connected to the valve block to discharge the natural gas flowing into the BOG line (BL) when the passage of the natural gas within the first valve (30) communicating with the cylinder (12) is closed.

3. In Paragraph 1 or 2, A backflow prevention valve (CV3) installed in the middle of the above unreacted hydrogen gas line (FL) to prevent natural vaporized gas released within the first and second valves (30)(40) from flowing back; A liquid hydrogen fuel supply system using BOG pressure, further comprising 4. A positive displacement pump (10) installed in the middle of a fuel supply line (DL) connecting a hydrogen fuel tank (T) and a fuel cell, wherein a plunger (11) reciprocates within a cylinder (12) by the pressure of natural vaporized gas evaporated and vaporized from the liquid hydrogen (LH2) in the hydrogen fuel tank (T), sucks in the liquid hydrogen (LH2) in the hydrogen fuel tank (T) according to the opening and closing of first and second check valves (CV1) (CV2) installed in the middle of the fuel supply line (DL), and pressurizes and pumps the liquid hydrogen (LH2) in the hydrogen fuel tank (T) through the fuel supply line (DL); A pressure regulator (20) installed in the middle of a BOG line (BL) that discharges natural vaporized gas evaporated and vaporized from liquid hydrogen (LH2) in the hydrogen fuel tank (T), and which regulates the pressure of the natural vaporized gas and supplies it to the positive displacement pump (10); A valve block that controls the supply of naturally vaporized gas, whose pressure is regulated through the pressure regulator (20), into the cylinder (12) by changing the flow path of the first valve (30) and the second valve (40) formed inside, and controls the release of naturally vaporized gas within the cylinder (12) through the unreacted hydrogen gas line (FL); A first touch switch (50) that detects when the plunger (11) is positioned at the top dead center within the cylinder (12), opens the passage of natural vaporized gas within the first valve (30) communicating with the cylinder (12), and closes the passage of natural vaporized gas within the second valve (40) communicating with the cylinder (12); and A second touch switch (60) that detects when the plunger (12) is positioned at the bottom dead center within the cylinder (12), closes the passage of natural vaporized gas within the first valve (30) communicating with the cylinder (12), and opens the passage of natural vaporized gas within the second valve (40) communicating with the cylinder (12); A liquid hydrogen fuel supply system utilizing BOG pressure, comprising

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