KR20230142947A - Cryogenic reciprocating pump for generating high pressure liquid using tension, and operating method thereof - Google Patents

Abstract

It is a cryogenic reciprocating pump, with a space formed inside, an inlet formed at the bottom through which liquid flows in from the outside, and an outlet formed at the top through which liquid pressurized to the target pressure is discharged, of the chamber A piston that divides the interior into the top and bottom of the chamber and moves up and down, a rod connected to the piston and moves the piston up and down according to the tension that pulls upward and the stress that presses down, and a rod that opens and closes according to the pressure difference between both ends and moves at the inlet. It includes a plurality of check valves that form a liquid flow in the outlet direction. While the rod is raised by upward pulling tension, the liquid at the top of the chamber is pressurized by the piston to the target pressure.

Description

Cryogenic reciprocating pump for generating high pressure liquid using tension and operating method thereof {CRYOGENIC RECIPROCATING PUMP FOR GENERATING HIGH PRESSURE LIQUID USING TENSION, AND OPERATING METHOD THEREOF}

The present invention relates to cryogenic reciprocating pumps.

A cryogenic reciprocating pump is a device that increases the pressure of cryogenic liquid. It compresses the cryogenic liquid with a piston or plunger to create high pressure. In the case of a conventional cryogenic reciprocating pump, a rod connected to a piston/plunger moves up and down in a liquefied hydrogen chamber, and when the rod moves down, the liquefied hydrogen is compressed and becomes high pressure. Therefore, in the prior art, in order to create high-pressure liquid, compressive stress is repeatedly applied to a long bar, which causes buckling, which bends sideways compared to the case where tensile stress of the same magnitude is applied. The likelihood of occurrence increases. To prevent this, a thick rod can be used, but the cross-sectional area of the rod increases heat transfer to the chamber, and the heat capacity of the rod increases, increasing the consumption of cryogenic liquid at the beginning of pump operation.

(Patent Document 1) KR20140098824 A

(Patent Document 2) US6722866 B

The present disclosure provides a cryogenic reciprocating pump that generates high pressure liquid using tension and a method of operating the same.

The present disclosure provides a cryogenic reciprocating pump including a backup relief valve and a method of operating the same.

It is a cryogenic reciprocating pump according to an embodiment, in which a space is formed inside, an inlet through which liquid flows in from the outside is formed at the bottom, and an outlet through which liquid pressurized to the target pressure is discharged is formed at the top. A chamber, a piston that divides the inside of the chamber into the upper part of the chamber and the lower part of the chamber and moves up and down, a rod connected to the piston and moves the piston up and down according to the upward tension and downward pressure, and the pressure difference between the two ends. It includes a plurality of check valves that open and close to form a liquid flow from the inlet to the outlet, and while the rod is raised by upward pulling tension, the liquid at the top of the chamber is pressurized by the piston to the target pressure.

While the rod is raised by upward pulling tension, external liquid flows into the bottom of the chamber through a first check valve disposed at the inlet, and liquid pressurized to the target pressure through a second check valve disposed at the outlet. may be emitted.

While the rod is lowered by downward pressure, the supercooled liquid from the bottom of the chamber can move to the top of the chamber through the third check valve.

An internal flow path from the bottom of the chamber to the bottom of the chamber is formed inside the piston, and when the third check valve disposed in the internal flow path is opened, liquid at the bottom of the chamber passes through the piston and flows into the top of the chamber. You can.

The internal flow path formed in the piston may be formed in a structure that protrudes toward the bottom of the chamber.

The cryogenic reciprocating pump further includes a backup relief valve that opens when the pressure at the bottom of the chamber exceeds the reference pressure, and liquid and/or gas at the bottom of the chamber can be discharged to the outside through the opened backup relief valve.

The cracking pressure of the backup relief valve may be set to the reference pressure.

The backup relief valve may be disposed at the bottom dead center of the piston.

The liquid flowing into the inlet may be cryogenic liquefied hydrogen.

The cryogenic reciprocating pump according to one embodiment moves the supercooled liquid from the bottom of the chamber to the top of the chamber while the stress is applied in a situation where downward pressure and upward tension are alternately applied with a rod connected to a piston in the chamber. , while the tension is applied, the liquid at the top of the chamber is pressurized to the target pressure and discharged.

While the stress is applied, if the pressure at the bottom of the chamber exceeds the reference pressure, liquid and/or gas at the bottom of the chamber may be discharged to the outside through a backup relief valve.

While the tension is applied, liquid may flow from the outside into the bottom of the chamber, and the introduced liquid may be supercooled.

A method of operating a cryogenic reciprocating pump according to one embodiment, comprising: moving supercooled liquid from the bottom of the chamber to the top of the chamber while a stress is applied to press down a rod connected to a piston in the chamber, and tension pulling the rod upward. While this is being applied, the liquid at the top of the chamber is pressurized to the target pressure and discharged.

The operating method may further include discharging liquid and/or gas at the bottom of the chamber to the outside through a backup relief valve when the pressure at the bottom of the chamber exceeds the reference pressure while the stress is applied. .

The operating method may further include introducing liquid from the outside into the bottom of the chamber while the tension is applied, and supercooling the introduced liquid.

The cryogenic reciprocating pump according to the embodiment generates high-pressure liquid using tension and applies compressive stress to the rod enough to generate flow, so buckling occurs compared to technology that creates high-pressure liquid by applying large compressive stress to the rod. It can lower the possibility.

The cryogenic reciprocating pump according to the embodiment can use a relatively thin rod compared to the prior art, thereby reducing heat intrusion through the rod extending externally.

Since the cryogenic reciprocating pump according to the embodiment has a downward inlet, it can operate even at low water levels in the cryogenic liquid reservoir.

In a cryogenic reciprocating pump in which the top of the chamber with a rod and the bottom of the chamber without the rod are divided by a piston with a rod, unwanted pressure increases due to the difference in cross-sectional area between the top and bottom of the chamber due to the rod. The cryogenic reciprocating pump regulates internal pressure through a backup relief valve, thereby eliminating the unwanted pressure increase that inevitably occurs in cryogenic reciprocating pumps that use tension.

The cryogenic reciprocating pump according to the embodiment can increase safety by preventing the generation of high pressure outside the design range inside the chamber, and can increase convenience of maintenance by easily replacing the backup relief valve.

The cryogenic reciprocating pump according to the embodiment can remove internal gas (bubbles), thereby preventing performance degradation due to evaporation of externally introduced liquid.

1 and 2 are structural diagrams of a cryogenic reciprocating pump according to one embodiment.
Figure 3 is a diagram explaining the difference in cross-sectional area between the top and bottom of the chamber due to the rod in the cryogenic reciprocating pump.
Figure 4 is a diagram explaining unwanted high pressure generated in a cryogenic reciprocating pump.
5 and 6 are structural diagrams of a cryogenic reciprocating pump according to another embodiment.
Figure 7 is a method of operating a cryogenic reciprocating pump according to one embodiment.
Figure 8 is a conceptual diagram of a hydrogen supply system according to one embodiment.

Below, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification, when a part is said to “include” a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary.

First, let's look at the prior art.

The cryogenic reciprocating pump developed by Linde in Germany has a double acting piston and plunger structure. A rod connected to the piston/plunger moves up and down between the upper chamber where the liquid flows and the lower chamber where the liquid is pressurized, producing high pressure. Makes a liquid. Looking at the specific operation, when the rod comes down, external liquid enters the upper part of the upper chamber, and the liquid filled in the lower part of the upper chamber is pressurized and becomes supercooled. When the pressure reaches a certain level, the supercooled liquid enters the lower part of the upper chamber. It is injected into the upper part of the chamber, and the liquid filled in the lower part of the lower chamber is pressurized to the target pressure and then discharged. When the bar rises, the liquid filled in the upper part of the upper chamber flows into the lower part of the upper chamber, and the supercooled liquid in the upper part of the lower chamber flows into the lower part of the lower chamber.

Looking at Patent Document 1 of French Cryostar SAS, the liquid entering the chamber enters the pressurized space and the liquid is pressurized through the plunger.

In this way, in the prior art, in order to create high-pressure liquid, compressive stress, which is a pressing force, is repeatedly applied to a long bar, so that it bends sideways compared to when tensile stress, which is a pulling force of the same magnitude, is applied. The likelihood of buckling increases. To prevent this, a thick rod can be used, but the cross-sectional area of the rod increases heat transfer to the chamber, and the heat capacity of the rod increases, increasing the consumption of cryogenic liquid at the beginning of pump operation.

In the case of Patent Document 2, the tension applied to the rod and the spring restoring force are used to create a flow of liquid inflow, pressure, and movement, but there are limits to pump control using springs due to brittleness at cryogenic temperatures.

In order to solve the problems of the prior art, the cryogenic reciprocating pump of the present disclosure has a structure that generates high-pressure liquid using tension, which will be described in detail below.

In the present disclosure, a cryogenic liquid is pressurized by a cryogenic reciprocating pump, and liquefied hydrogen of about 20K can be used as an example as the cryogenic liquid.

1 and 2 are structural diagrams of a cryogenic reciprocating pump according to one embodiment.

Referring to FIGS. 1 and 2, a cryogenic reciprocating pump (100A, 100B) is a device that increases the pressure of cryogenic liquid. It receives cryogenic liquid (e.g., normal pressure liquid) and pressurizes it. Discharges high pressure (e.g. 900 bar) cryogenic liquid. Cryogenic liquids are generally stored in a saturated liquid state, so they easily evaporate due to small heat intrusion or flow. If liquid evaporates inside the pump during pump operation, the overall specific volume may increase and the volumetric efficiency after compression may decrease. Therefore, the cryogenic reciprocating pumps (100A, 100B) slightly pressurize the saturated liquid introduced from the outside at the bottom of the chamber to make it supercooled, and bring the supercooled liquid to a target high pressure (e.g., 900 bar) at the top of the chamber. Proceed with step 2 pressurization.

Cryogenic reciprocating pumps (100A, 100B) generate and discharge high-pressure liquid when tension is applied to the rod to which the piston is connected. In other words, the cryogenic reciprocating pumps (100A, 100B) apply a pressing force to the rod to move the supercooled liquid from the bottom of the chamber to the top of the chamber, and apply a pulling force (tension) to the rod to target the supercooled liquid at the top of the chamber with tension. Pressurize to pressure and discharge. At this time, a flow path through which the supercooled liquid from the bottom of the chamber flows to the top of the chamber may be formed inside the piston as shown in FIG. 1, or may be formed outside the chamber as shown in FIG. 2.

Referring to Figure 1, the cryogenic reciprocating pump (100A) has a chamber (110A) with a space formed inside, the inside of the chamber (110A) is separated into the upper part of the chamber and the lower part of the chamber, and a piston (120A) that moves up and down is connected to the piston (120A). a rod 130A that moves the piston up and down, and a plurality of check valves 141A, 142A that open and close according to the pressure difference between the top and bottom of the chamber to form a liquid flow from the inlet to the outlet. 143A) may be included. In the case of the cryogenic reciprocating pump (100A), a flow path from the bottom of the chamber to the bottom of the chamber may be formed inside the piston (120A). A check valve (143A) is formed on the piston (120A), and when the check valve (143A) is opened, liquid at the bottom of the chamber can pass through the piston (120A) and flow into the top of the chamber.

Meanwhile, when the piston 120A rises, the external liquid in a saturated state enters the bottom of the chamber due to the pressure difference, and the cryogenic liquid inevitably evaporates at the bottom of the chamber, generating bubbles. Therefore, to prevent gas at the bottom of the chamber from flowing into the internal flow path of the piston 120A, the piston 120A is formed in a structure in which the end of the internal flow path protrudes toward the bottom of the chamber. Through this, it is possible to prevent the evaporated gas from being trapped in the upper part of the bottom of the chamber and flowing into the internal flow path of the piston (120A).

Referring to Figure 2, the cryogenic reciprocating pump (100B) has a chamber (110B) with a space formed inside, the inside of the chamber (110B) is separated into the upper part of the chamber and the lower part of the chamber, and a piston (120B) that moves up and down is connected to the piston (120B). a rod (130B) that moves the piston up and down, a plurality of check valves (141B, 142B, 143B) that open and close according to the pressure difference between the upper and lower chambers to form a liquid flow from the inlet to the outlet, and at the bottom of the chamber It may include an external flow path (150B) connecting the top of the chamber. In the case of the cryogenic reciprocating pump (100B), a check valve (143B) is disposed at the bottom of the chamber, and when the check valve (143B) is opened, liquid at the bottom of the chamber may flow into the top of the chamber through the external flow path (150B).

The chambers 110A and 110B are separated into upper and lower parts by pistons 120A and 120B. The volumes of the upper and lower chambers vary depending on the positions of the pistons 120A and 120B. The lower chamber is a space that stores liquid introduced from the outside and supercools the liquid to prevent evaporation before pressurizing the liquid. The upper chamber is a space where the supercooled liquid introduced from the lower chamber is pressurized to the target pressure and discharged to the outside.

The pistons (120A, 120B) move up and down by the force applied to the rods (130A, 130B). In the case of the piston 120A, a flow path from the bottom of the chamber to the bottom of the chamber may be formed inside.

The rods 130A and 130B extend outside the cryogenic reciprocating pumps 100A and 100B and reciprocate by an external actuator (not shown). When a pulling force (tension) is applied to the rods (130A, 130B), the connected pistons (120A, 120B) rise upward, and when a pressing force is applied to the rods (130A, 130B), the connected pistons (120A, 120B) move downward. Go down to The range of motion of the rods 130A and 130B may be determined depending on chamber capacity and pressure.

The inlet of the cryogenic reciprocating pump (100A, 100B) is formed near the bottom surface of the chamber (110A, 110B), and the outlet (outlet) is formed near the top surface of the chamber (110A, 110B). The inlet may be immersed in an atmospheric pressure cryogenic liquid reservoir or connected to an atmospheric pressure cryogenic liquid reservoir. The outlet may be connected to a cryogenic liquid reservoir near the target high pressure. Accordingly, in the cryogenic reciprocating pumps 100A and 100B, the liquid flows from bottom to top and is discharged.

Check valves are valves that allow liquid to flow in only one direction, from the bottom inlet to the top outlet. Check valves open when a pressure difference occurs in one direction, and close otherwise.

The check valves 141A and 141B are disposed at the inlet and create a fluid flow that causes external liquid to flow into the bottom of the chamber. Check valves 142A and 142B are disposed at the outlet and create a fluid flow that discharges the high-pressure liquid at the top of the chamber to the outlet.

The check valve 143A is disposed in the internal flow path of the piston 120A and creates a fluid flow that moves the supercooled liquid at the bottom of the chamber to the top of the chamber. The check valve 143B may be disposed in the external flow path 150B and creates a fluid flow that moves the subcooled liquid at the bottom of the chamber to the top of the chamber.

In addition, an insulator may be added to the cryogenic reciprocating pumps (100A, 100B) to prevent heat intrusion. Dynamic seals may be added to the cryogenic reciprocating pumps 100A and 100B to prevent leakage that may occur at the moving part of the rod. A device for reliquefying the leaked gas or a device for transporting the leaked gas to a separate gas storage may be added to the cryogenic reciprocating pumps 100A and 100B.

When a pulling force (tension) is applied to the rods 130A and 130B, the pistons 120A and 120B connected to the rods 130A and 130B move upward. As the rod rises, the bottom of the chamber expands and the top of the chamber compresses. Accordingly, the check valves 143A and 143B, which create a fluid flow from the bottom of the chamber to the top of the chamber, are closed due to the pressure at the bottom of the chamber being lower than that of the top of the chamber. Instead, the check valves 141A and 141B are opened due to the pressure at the bottom of the chamber being lower than the inlet, so that external liquid and cryogenic fluid at normal pressure flow into the bottom of the chamber. Additionally, while the rod rises, the liquid at the top of the chamber is pressurized, and when the target pressure is reached, a pressure difference with the outlet occurs and the check valves 142A and 142B open. Then, the high-pressure liquid pressurized at the top of the chamber is discharged to the outlet through the check valves 142A and 142B.

When a pressing force (stress) is applied to the rods 130A and 130B, the pistons 120A and 120B move down. As the rod is lowered, the bottom of the chamber is compressed and the top of the chamber expands. Accordingly, the check valves 143A and 143B open due to the pressure at the bottom of the chamber being higher than that at the top of the chamber, and fluid flows from the bottom of the chamber to the top of the chamber. Meanwhile, the check valves 141A and 141B, which create a fluid flow from the inlet to the bottom of the chamber, are closed due to the pressure at the bottom of the chamber being higher than the inlet. Additionally, while the rod is rising, the check valves 142A and 142B, which create a fluid flow from the top of the chamber to the outlet, are closed due to the pressure at the top of the chamber being lower than the outlet.

When the bars 130A, 130B are raised to the designated highest point, the force applied to the bars 130A, 130B switches from an upward pulling tension to a downward pressing stress, and when the bars 130A, 130B are lowered to the designated lowest point, As the force applied to the rods 130A and 130B is switched, the reciprocating motion may be repeated.

In this way, the liquid is pressurized when the rods 130A and 130B go up, and when the rods 130A and 130B go down, the liquid moves from the bottom of the chamber to the top of the chamber. Therefore, the cryogenic reciprocating pumps (100A, 100B) generate high-pressure liquid using tension and apply compressive stress to the rod 130 enough to generate flow, thereby creating high-pressure liquid by applying large compressive stress to the rod. Compared to the prior art, there is less possibility of sideways buckling. Ultimately, the cryogenic reciprocating pumps (100A, 100B) can use relatively thin rods compared to the prior art, thereby reducing heat intrusion through the rod extending to the outside. Additionally, since the cryogenic reciprocating pumps 100A and 100B have downward inlets, they can operate even at low water levels in the cryogenic liquid reservoir. Accordingly, the minimum amount required to be stored in cryogenic liquid storage can be reduced.

FIG. 3 is a diagram explaining the difference in cross-sectional area between the top and bottom of the chamber due to the rod in the cryogenic reciprocating pump, and FIG. 4 is a diagram explaining the unwanted high pressure generated in the cryogenic reciprocating pump.

Referring to FIG. 3, the cryogenic reciprocating pumps (100A, 100B) using tension have different cross-sectional areas at the top and bottom of the chamber due to the rods (130A, 130B). Comparing the cross-sectional area (A) of the top of the chamber where the rod (130A/130B) moves and the cross-sectional area (A') of the bottom of the chamber without the rod (130A/130B), the cross-sectional area of the space where the liquid can stay at the top of the chamber is the rod. narrowed by Therefore, when the pistons 120A and 120B go down or up, the chamber effective volume, which is the sum of the volumes of the upper and lower chambers, changes. In particular, cryogenic liquids are incompressible fluids, so unwanted pressure increases may occur due to changes in internal volume.

Since the bottom of the chamber of the cryogenic reciprocating pump (100A, 100B) only needs to supercool the liquid, the pressure outside the pump may be slightly higher (for example, about 3 bar) and is designed to withstand this pressure. However, when the pistons 120A and 120B descend, an unwanted increase in pressure may occur at the bottom of the chamber due to the difference in cross-sectional area between the top and bottom of the chamber. Referring to FIG. 4, it is shown that due to the difference in cross-sectional area between the top and bottom of the chamber, the pressure at the bottom of the chamber may be as large as the top of the chamber. Therefore, it may also affect the essential purpose of the cryogenic reciprocating pumps (100A, 100B), which is to generate high pressure using tension.

In addition, the cryogenic reciprocating pumps 100A and 100B are immersed in a liquefied hydrogen Dewar storing cryogenic liquid, and the cryogenic liquid is generally in a saturated state. Saturated liquids evaporate easily due to small pressure drops or heat influx. When the pistons (120A, 120B) rise, the external liquid in a saturated state enters the bottom of the chamber due to the pressure difference. As shown in Figures 1 and 2, the cryogenic liquid inevitably evaporates at the bottom of the chamber and bubbles are generated. . Since gas has a much larger specific volume than liquid, the gas inside the chamber reduces the mass flow rate that the pump pressurizes in one stroke and can cause a decrease in pump performance.

In the following, an improved pump that prevents unwanted pressure increases in tension-based cryogenic reciprocating pumps (100A, 100B) and removes air bubbles in the chamber will be described.

5 and 6 are structural diagrams of a cryogenic reciprocating pump according to another embodiment.

Referring to FIGS. 5 and 6 , the cryogenic reciprocating pumps 200A and 200B can be improved on the cryogenic reciprocating pumps 100A and 100B through backup relief valves 260A and 260B.

Referring to Figure 5, the cryogenic reciprocating pump (200A), like the cryogenic reciprocating pump (100A), has a chamber (210A) with a space formed inside, the inside of the chamber (210A) is divided into the upper part of the chamber and the lower part of the chamber, and a piston ( 220A), a rod (230A) connected to the piston (220A) to move the piston up and down, and a plurality of bars that open and close according to the pressure difference between the top and bottom of the chamber to form a liquid flow from the inlet to the outlet. It may include check valves (241A, 242A, 243A). The cryogenic reciprocating pump (200A) further includes a backup relief valve (260A).

Referring to Figure 6, the cryogenic reciprocating pump (200B), like the cryogenic reciprocating pump (100B), has a chamber (210B) with a space formed inside, the inside of the chamber (210B) is divided into the upper part of the chamber and the lower part of the chamber, and a piston ( 220B), a rod 230B connected to the piston 220B to move the piston up and down, and a plurality of bars that open and close according to the pressure difference between the top of the chamber and the bottom of the chamber to form a liquid flow from the inlet to the outlet. It may include check valves (241B, 242B, 243B). The cryogenic reciprocating pump (200B) further includes a backup relief valve (260B).

As described in FIGS. 1 and 2, the chambers 210A and 110B are separated into upper and lower parts by pistons 220A and 220B. The volumes of the upper and lower chambers vary depending on the positions of the pistons 220A and 220B. The lower chamber is a space that stores liquid introduced from the outside and supercools the liquid to prevent evaporation before pressurizing the liquid. The upper chamber is a space where the supercooled liquid introduced from the lower chamber is pressurized to the target pressure and discharged to the outside.

The pistons (220A, 220B) move up and down by the force applied to the rods (230A, 130B). In the case of the piston 220A, a flow path from the bottom of the chamber to the bottom of the chamber may be formed inside. The piston 220A is formed in a structure in which the end of the internal flow path protrudes toward the bottom of the chamber to prevent gas at the bottom of the chamber from flowing into the internal flow path.

The rods 230A and 230B extend outside the cryogenic reciprocating pumps 200A and 200B, and reciprocate by an external driving device (not shown). When a pulling force (tension) is applied to the rods (230A, 230B), the connected pistons (220A, 220B) rise upward, and when a pressing force is applied to the rods (230A, 230B), the connected pistons (220A, 220B) move downward. Go down to The range of motion of the rods 230A and 230B may be determined depending on chamber capacity and pressure.

The inlet of the cryogenic reciprocating pump (200A, 200B) is formed near the bottom surface of the chamber (210A, 210B), and the outlet is formed near the upper surface of the chamber (210A, 110B). The inlet may be immersed in an atmospheric pressure cryogenic liquid reservoir or connected to an atmospheric pressure cryogenic liquid reservoir. The outlet may be connected to a cryogenic liquid reservoir near the target high pressure. Accordingly, in the cryogenic reciprocating pumps 200A and 200B, the liquid flows from bottom to top and is discharged.

The check valves 241A and 241B are disposed at the inlet and create a fluid flow that causes external liquid to flow into the bottom of the chamber. Check valves 242A and 242B are disposed at the outlet and create a fluid flow that discharges the high-pressure liquid at the top of the chamber to the outlet. The check valve 243A is disposed in the internal flow path of the piston 220A and creates a fluid flow that moves the supercooled liquid at the bottom of the chamber to the top of the chamber. The check valve 243B may be disposed in the external flow path 250B and creates a fluid flow that moves the subcooled liquid at the bottom of the chamber to the top of the chamber.

The backup relief valves 260A and 260B are valves that control the pressure at the bottom of the chamber so that it does not exceed the reference pressure. Backup relief valves 260A and 260B open when the pressure at the bottom of the chamber exceeds the reference pressure. Through the open backup relief valves 260A and 260B, gas as well as liquid at the bottom of the chamber can be discharged to the outside. The cracking pressure at which the backup relief valves (260A, 260B) discharge liquid/gas is designed to be greater than that of the check valve that generates fluid flow. The cracking pressure of the backup relief valves 260A and 260B may be the reference pressure at the bottom of the chamber.

The backup relief valves 260A and 260B may be disposed at the bottom dead center of the pistons 220A and 220B, where gas is collected, so that the evaporated gas is discharged to the outside.

As described in FIGS. 1 and 2, when a pulling force (tension) is applied to the bars 230A and 230B, the bars 230A and 230B move upward. As the rod rises, the bottom of the chamber expands and the top of the chamber compresses. Accordingly, the check valves 243A and 243B, which create a fluid flow from the bottom of the chamber to the top of the chamber, are closed due to the pressure at the bottom of the chamber being lower than that of the top of the chamber. Instead, the check valves 241A and 241B are opened due to the pressure at the bottom of the chamber being lower than the inlet, so that external liquid and cryogenic fluid at normal pressure flow into the bottom of the chamber. Additionally, while the rod rises, the liquid at the top of the chamber is pressurized, and when the target pressure is reached, a pressure difference with the outlet occurs and the check valves 242A and 242B open. Then, the high-pressure liquid pressurized at the top of the chamber is discharged to the outlet through the check valves 242A and 242B. At this time, since the bottom of the chamber expands and is lower than the reference pressure, the backup relief valves 260A and 260B, which have the reference pressure as the cracking pressure, are closed.

When a pressing force (stress) is applied to the bars 230A and 230B, the bars 230A and 130B move down. As the rod is lowered, the bottom of the chamber is compressed and the top of the chamber expands. Accordingly, the check valves 243A and 243B open due to the pressure at the bottom of the chamber being higher than that at the top of the chamber, and fluid flows from the bottom of the chamber to the top of the chamber. Meanwhile, the check valves 241A and 241B, which create a fluid flow from the inlet to the bottom of the chamber, are closed due to the pressure at the bottom of the chamber being higher than the inlet. Additionally, while the rod is rising, the check valves 242A and 242B, which create a fluid flow from the top of the chamber to the outlet, are closed due to the pressure at the top of the chamber being lower than the outlet. Meanwhile, while a pressing force is applied to the rods 230A and 230B, the pressure at the bottom of the chamber may increase due to the difference in cross-sectional area between the upper and lower chambers and exceed the designed reference pressure. Then, the backup relief valves 260A and 260B, which have the reference pressure as the cracking pressure, are opened and the liquid/gas at the bottom of the chamber is discharged to the outside, thereby preventing the pressure at the bottom of the chamber from rising beyond the reference pressure. In addition, since gas with a specific volume much larger than the liquid is discharged through the open backup relief valves 260A and 260B, gas (bubbles) inside the chamber that causes deterioration of pump performance can be removed.

When the bars 230A, 230B are raised to the specified highest point, the force applied to the bars 230A, 230B switches from an upward pulling tension to a downward pressing stress, and when the bars 230A, 230B are lowered to the designated lowest point, As the force applied to the rods 230A and 230B is switched, the reciprocating motion may be repeated.

Figure 7 is a method of operating a cryogenic reciprocating pump according to one embodiment.

Referring to FIG. 7, the cryogenic reciprocating pump of the present disclosure moves the supercooled liquid from the bottom of the chamber to the top of the chamber while a downward stress is applied to the rod connected to the piston in the chamber (S110). Meanwhile, while the stress pressing the rod is applied, if the pressure at the bottom of the chamber exceeds the reference pressure, the liquid and/or gas at the bottom of the chamber is discharged to the outside through the backup relief valves 260A and 260B.

The cryogenic reciprocating pump of the present disclosure pressurizes and discharges the liquid at the top of the chamber to the target pressure while an upward pulling tension is applied to the rod (S120). Meanwhile, while tension is applied to pull the rod, liquid flows into the bottom of the chamber from the outside.

At this time, the stress pressing the rod down and the tension pulling the rod upward are applied alternately, allowing the rod and piston to move up and down.

In this way, the cryogenic reciprocating pump according to the embodiment generates high-pressure liquid using tension and applies compressive stress to the rod enough to generate flow, compared to technology that creates high-pressure liquid by applying large compressive stress to the rod. It can reduce the possibility of buckling occurring.

The cryogenic reciprocating pump according to the embodiment can use a relatively thin rod compared to the prior art, thereby reducing heat intrusion through the rod extending externally.

Since the cryogenic reciprocating pump according to the embodiment has a downward inlet, it can operate even at low water levels in the cryogenic liquid reservoir.

In a cryogenic reciprocating pump in which the top of the chamber with a rod and the bottom of the chamber without the rod are divided by a piston with a rod, unwanted pressure increases due to the difference in cross-sectional area between the top and bottom of the chamber due to the rod. The cryogenic reciprocating pump regulates internal pressure through a backup relief valve, thereby eliminating the unwanted pressure increase that inevitably occurs in cryogenic reciprocating pumps that use tension.

The cryogenic reciprocating pump according to the embodiment can increase safety by preventing the generation of high pressure outside the design range inside the chamber, and can increase convenience of maintenance by easily replacing the backup relief valve.

The cryogenic reciprocating pump according to the embodiment can remove internal gas (bubbles), thereby preventing performance degradation due to evaporation of externally introduced liquid.

Figure 8 is a conceptual diagram of a hydrogen supply system according to one embodiment.

Referring to FIG. 8, it is effective to store hydrogen as cryogenic liquefied hydrogen rather than as gaseous hydrogen at room temperature. Therefore, the hydrogen charging station stores liquefied hydrogen in the liquid hydrogen storage (10) and supplies hydrogen vehicles ( 20) Supply liquefied hydrogen.

Liquefied hydrogen has a higher density than gaseous hydrogen, so its volumetric efficiency is high. Additionally, the hydrogen used in hydrogen vehicles must be of high purity, so when using gaseous hydrogen, it is necessary to remove impurities such as moisture or dust. However, when liquefied hydrogen is vaporized and injected into a hydrogen vehicle, impurities are removed during the hydrogen liquefaction process, so a separate high purification operation required when using gaseous hydrogen is not necessary. Therefore, the hydrogen supply process using liquefied hydrogen is simplified.

Meanwhile, the hydrogen vehicle 20 receives hydrogen at a pressure of 350 bar to 700 bar, and in order to supply hydrogen using the pressure difference at the hydrogen charging station, high-pressure liquefied hydrogen (e.g., 900 bar) higher than 700 bar is used. It must be stored in the liquefied hydrogen storage (10). The liquid hydrogen pump supplies high-pressure liquid hydrogen to the liquid hydrogen storage 10, and the cryogenic reciprocating pumps 100A, 100B, 200A, and 200B of the present disclosure may be used.

The cryogenic reciprocating pumps (100A, 100B, 200A, 200B) receive normal pressure liquefied hydrogen from the liquefied hydrogen Dewar (300) and supply high-pressure liquefied hydrogen of 900 bar to the liquefied hydrogen storage (10). can be discharged. The inlet of the cryogenic reciprocating pump 100 may be immersed in the liquid hydrogen dewar 300 or may receive liquid hydrogen from the liquid hydrogen dewar 300.

In addition to hydrogen refueling stations, cryogenic reciprocating pumps (100A, 100B, 200A, 200B) can be used to transport cryogenic liquids and transport cryogenic liquids to high altitudes.

There is increasing interest in the liquid air energy storage (LAES) system as a next-generation large-capacity energy storage method. LAES operates an air liquefaction plant with surplus power to liquefy air, pressurizes the liquefied air to high pressure when electrical energy is needed, raises the temperature through heat exchange, and operates a turbine using the expansion force when changing from liquid to gas. to reproduce energy. Currently, the LAES system is in the early stages of research worldwide, so the degree of pressurizing the liquid is not standardized, but the cryogenic reciprocating pumps (100A, 100B, 200A, 200B) of the present disclosure can be used in this field.

The embodiments of the present invention described above are not only implemented through devices and methods, but can also be implemented through programs that implement functions corresponding to the configurations of the embodiments of the present invention or recording media on which the programs are recorded.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims are also possible. It falls within the scope of rights.

Claims (15)

As a cryogenic reciprocating pump,
A chamber with a space formed inside, an inlet formed at the bottom through which liquid flows in from the outside, and an outlet formed at the top through which liquid pressurized to the target pressure is discharged,
A piston that divides the interior of the chamber into the upper chamber and the lower chamber and moves up and down,
A rod connected to the piston and moving the piston up and down depending on the upward tension and downward pressure, and
It includes a plurality of check valves that open and close according to the pressure difference between both ends to form a liquid flow from the inlet to the outlet,
A cryogenic reciprocating pump, wherein the liquid at the top of the chamber is pressurized by the piston to the target pressure while the rod is raised by upward pulling tension. In paragraph 1:
While the rod is raised by upward pulling tension, external liquid flows into the bottom of the chamber through a first check valve disposed at the inlet, and liquid pressurized to the target pressure through a second check valve disposed at the outlet. A cryogenic reciprocating pump that discharges In paragraph 1:
A cryogenic reciprocating pump in which subcooled liquid from the bottom of the chamber moves to the top of the chamber through a third check valve while the rod is lowered by downward pressure. In paragraph 3,
An internal flow path from the bottom of the chamber to the bottom of the chamber is formed inside the piston, and when the third check valve disposed in the internal flow path is opened, liquid at the bottom of the chamber passes through the piston and flows into the top of the chamber. , cryogenic reciprocating pump. In paragraph 4,
The internal flow path formed in the piston is formed in a structure that protrudes toward the bottom of the chamber. In paragraph 1:
Further comprising a backup relief valve that opens when the pressure at the bottom of the chamber exceeds the reference pressure,
A cryogenic reciprocating pump in which liquid and/or gas at the bottom of the chamber is discharged to the outside through the open backup relief valve. In paragraph 6:
The cracking pressure of the backup relief valve is set to the reference pressure. In paragraph 6:
The backup relief valve is
A cryogenic reciprocating pump disposed at the bottom dead center of the piston. In paragraph 1:
A cryogenic reciprocating pump in which the liquid flowing into the inlet is cryogenic liquefied hydrogen. In a situation where a downward pressing stress and an upward pulling tension are alternately applied by a rod connected to a piston in the chamber, the supercooled liquid is moved from the bottom of the chamber to the top of the chamber while the stress is applied, and the top of the chamber is moved while the tension is applied. A cryogenic reciprocating pump that pressurizes and discharges liquid to the target pressure. In paragraph 10:
While the stress is applied, if the pressure at the bottom of the chamber exceeds the reference pressure, the liquid and/or gas at the bottom of the chamber is discharged to the outside through a backup relief valve. In paragraph 10:
A cryogenic reciprocating pump in which liquid flows into the bottom of the chamber from the outside while the tension is applied, and the introduced liquid is supercooled. As a method of operating a cryogenic reciprocating pump,
moving the subcooled liquid from the bottom of the chamber to the top of the chamber while a stress is applied to press down on a rod connected to a piston in the chamber, and
Pressurizing and discharging the liquid at the top of the chamber to a target pressure while tension is applied to pull the rod upward.
An operation method comprising: In paragraph 13:
While the stress is applied, if the pressure at the bottom of the chamber exceeds the reference pressure, discharging the liquid and/or gas at the bottom of the chamber to the outside through a backup relief valve.
An operation method further comprising: In paragraph 13:
While the tension is applied, introducing liquid into the bottom of the chamber from the outside and supercooling the introduced liquid.
An operation method further comprising: