Low-temperature liquid two-stage supercharging system and low-temperature liquid two-stage supercharging assembly

Abstract

The application provides a low-temperature liquid two-stage supercharging system and a low-temperature liquid two-stage supercharging assembly. The low-temperature liquid two-stage supercharging system comprises a piston cylinder, a piston cavity is arranged in the piston cylinder; a piston is arranged in the piston cavity and movably connected with the piston cavity, so as to divide the piston cavity into a low-pressure cavity and a high-pressure cavity; a first liquid inlet and a first liquid outlet communicating with the low-pressure cavity and a second liquid inlet and a second liquid outlet communicating with the high-pressure cavity are arranged in the side wall of the piston cylinder; the first liquid inlet communicates with a liquid inlet pipe, a first one-way valve is arranged in the liquid inlet pipe; a through pipe is arranged between the first liquid outlet and the second liquid inlet; a second one-way valve is arranged in the through pipe; the second liquid outlet communicates with a liquid outlet pipe; and a third one-way valve is arranged in the liquid outlet pipe. A transmission shaft is movably connected with the piston cylinder at the first end and fixedly connected with the piston in the high-pressure cavity; and a driving assembly is drivingly connected with the second end of the transmission shaft. The application can achieve higher supercharging effect.

Description

Technical Field

[0001] This invention relates to the field of cryogenic supercharging technology, specifically to a cryogenic liquid two-stage supercharging system and a cryogenic liquid two-stage supercharging assembly. Background Technology

[0002] At low temperatures, gases can be stored in liquefied form in storage containers, achieving high storage density. Supplying liquefied gas to a vaporizer at high pressure allows for the direct acquisition of high-pressure gas without compression during the refueling process, making it far more efficient than gas compression.

[0003] To supply liquefied gas fuel at sufficiently high pressure to the vaporizer, a cryogenic booster pump is typically used to pump the liquefied gas. The pump pressure is transmitted via a drive shaft to the piston in the piston cylinder, where the cryogenic liquid is pressurized. During the stroke, the drive shaft and piston compress the liquid and discharge it. During the return stroke, the drive shaft and piston move in the opposite direction, allowing fresh liquid to enter the piston cylinder. In other words, the cryogenic liquid is only compressed and pressurized in one direction during the stroke. To reduce heat transfer between the cryogenic liquid and the drive shaft, a relatively long drive rod is usually used. This limits the ability of the unidirectional compression booster structure to achieve higher pressurization efficiency. Summary of the Invention

[0004] In view of this, the present invention provides a cryogenic liquid two-stage boosting system and a cryogenic liquid two-stage boosting assembly to solve the technical problem that existing cryogenic booster pumps cannot achieve higher boosting effects.

[0005] The cryogenic liquid two-stage pressurization system provided by this invention includes:

[0006] A piston cylinder, wherein a piston chamber is provided inside the piston cylinder;

[0007] A piston is disposed within a piston chamber and is movably connected to the piston chamber, dividing the piston chamber into a low-pressure chamber and a high-pressure chamber. The side wall of the piston cylinder is provided with a first inlet and a first outlet communicating with the low-pressure chamber, and a second inlet and a second outlet communicating with the high-pressure chamber. The first inlet is connected to an inlet pipe, and a first one-way valve is provided inside the inlet pipe. A connecting pipe is provided between the first outlet and the second inlet, and a second one-way valve is provided inside the connecting pipe. The second outlet is connected to an outlet pipe, and a third one-way valve is provided inside the outlet pipe.

[0008] A drive shaft, the first end of which passes through the piston cylinder and is movably connected to the piston cylinder, and is fixedly connected to the piston in the high-pressure chamber;

[0009] A drive assembly is driven to the second end of the drive shaft to drive the drive shaft to reciprocate along the piston cylinder.

[0010] Optionally, the cross-sectional area of ​​the first end of the drive shaft gradually increases in the direction toward the piston.

[0011] Optionally, the volume of the high-pressure chamber is set to 0.8-0.95 times the volume of the low-pressure chamber.

[0012] Optionally, the cryogenic liquid two-stage pressurization system further includes a coaxial positioner, which is sleeved on the drive shaft and fixedly connected to the piston cylinder.

[0013] Optionally, a first flange is installed at the end of the coaxial positioner away from the piston cylinder, and the first flange is fitted onto the drive shaft.

[0014] Optionally, a second flange is installed at the end of the piston cylinder away from the coaxial positioner.

[0015] Optionally, a first seal is provided between the drive shaft and the piston cylinder.

[0016] Optionally, the driving component includes:

[0017] A hydraulic cylinder, wherein a hydraulic chamber is provided inside the hydraulic cylinder;

[0018] A hydraulic piston is disposed within and movably connected to the hydraulic chamber, dividing the hydraulic chamber into a first chamber and a second chamber. A first inlet and a first outlet communicating with the first chamber, and a second inlet and a second outlet communicating with the second chamber are provided through the side wall of the hydraulic cylinder. The first inlet, first outlet, second inlet, and second outlet are respectively connected to a four-way directional valve. The second end of a drive shaft passes through the hydraulic cylinder, is movably connected to the hydraulic cylinder, and is fixedly connected to the hydraulic piston.

[0019] A hydraulic pump, wherein the outlet of the hydraulic pump is connected to the inlet of the four-way directional valve.

[0020] Optionally, a second seal is provided between the drive shaft and the hydraulic cylinder.

[0021] The present invention also provides a cryogenic liquid two-stage pressurization assembly, including a cryogenic liquid storage tank and a cryogenic liquid two-stage pressurization system as described in any of the above claims, wherein the inlet pipe of the cryogenic liquid two-stage pressurization system is immersed in the cryogenic liquid storage tank.

[0022] The technical solutions provided by this invention have at least the following beneficial effects compared with the prior art:

[0023] By using this invention, the piston is driven to reciprocate within the piston chamber by a drive assembly, so that the cryogenic liquid is initially pressurized in the low-pressure chamber and then enters the high-pressure chamber for secondary pressurization, thereby achieving a higher pressurization effect. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a cryogenic liquid two-stage pressurization system according to an embodiment of the present invention;

[0025] Figure 2 for Figure 1 A schematic diagram of the piston cylinder of the cryogenic liquid two-stage pressurization system is shown.

[0026] Figure 3 for Figure 1 The diagram shows the first check valve of the cryogenic liquid two-stage pressurization system.

[0027] Figure label:

[0028] 1: Piston cylinder; 2: Piston; 3: Drive shaft; 4: Drive assembly; 401: Hydraulic cylinder; 402: Hydraulic piston; 403: First chamber; 404: Second chamber; 405: First inlet; 406: First outlet; 407: Second inlet; 408: Second outlet; 5: Low-pressure chamber; 6: High-pressure chamber; 7: Inlet pipe; 8: Conductor pipe; 9: Outlet pipe; 10: Coaxial positioner; 11: First flange; 12: Second flange; 13: First seal; 14: Second seal. Detailed Implementation

[0029] The embodiments of the present invention will be further described below with reference to the accompanying drawings. In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the purpose of simplifying the description of the present invention and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0030] Figure 1 This is a schematic diagram of a cryogenic liquid two-stage pressurization system according to an embodiment of the present invention; Figure 2 for Figure 1 A schematic diagram of the piston cylinder of the cryogenic liquid two-stage pressurization system is shown. Figure 3 for Figure 1 The diagram shows the first check valve of the cryogenic liquid two-stage pressurization system.

[0031] like Figures 1-3 As shown, the cryogenic liquid two-stage pressurization system includes a piston cylinder 1, a piston 2, a drive shaft 3, and a drive assembly 4.

[0032] The piston cylinder 1 has a piston chamber; the piston 2 is disposed in the piston chamber and movably connected to the piston chamber, dividing the piston chamber into a low-pressure chamber 5 and a high-pressure chamber 6. The side wall of the piston cylinder 1 has a first inlet and a first outlet connecting the low-pressure chamber 5, and a second inlet and a second outlet connecting the high-pressure chamber 6. The first inlet is connected to an inlet pipe 7, and a first one-way valve is disposed in the inlet pipe 7. A connecting pipe 8 is connected between the first outlet and the second inlet, and a second one-way valve is disposed in the connecting pipe 8. The second outlet is connected to an outlet pipe 9, and a third one-way valve is disposed in the outlet pipe 9. The first end of the drive shaft 3 passes through the piston cylinder 1 and is movably connected to the piston cylinder 1, and is fixedly connected to the piston 2 in the high-pressure chamber 6. The drive assembly 4 is drivenly connected to the second end of the drive shaft 3 to drive the drive shaft 3 to reciprocate along the piston cylinder 1.

[0033] like Figure 1As shown, the high-pressure chamber 6 is located above the piston 2, and the low-pressure chamber 5 is located below the piston 2. When the system is working, the inlet pipe 7 is connected to the cryogenic liquid, and the drive assembly 4 is activated. The drive assembly 4 drives the transmission shaft 3 downwards, which in turn drives the piston 2 connected to the transmission shaft 3 towards the low-pressure chamber 5. At this time, the first one-way valve in the inlet pipe 7 is closed, and the cryogenic liquid in the low-pressure chamber 5 is initially compressed and pressurized. When the cryogenic liquid in the low-pressure chamber 5 is compressed to a set pressure, for example, 1-45 MPa, the second one-way valve in the connecting pipe 8 opens, and the initially pressurized cryogenic liquid flows into the high-pressure chamber 6 through the connecting pipe 8. After the high-pressure chamber 6 is filled, the drive assembly 4 is reversed, causing the transmission shaft 3 to move upwards. This, in turn, causes the piston 2 connected to the transmission shaft 3 to move towards the high-pressure chamber 6. At this time, the second one-way valve closes to prevent the cryogenic liquid from flowing back. The cryogenic liquid in the high-pressure chamber 6 is then compressed and pressurized a second time. When the cryogenic liquid in the high-pressure chamber 6 is compressed to a set pressure, for example, 70-90 MPa, the third one-way valve in the outlet pipe 9 opens. The secondary pressurized cryogenic liquid in the high-pressure chamber 6 is then transported to an external system, such as to a vaporizer, through the outlet pipe 9. During the movement of the piston 2 towards the high-pressure chamber 6, the first one-way valve opens, and the cryogenic liquid flows into the low-pressure chamber 5 through the inlet pipe 7. When a certain amount of the secondary pressurized cryogenic liquid in the high-pressure chamber 6 is discharged, the drive assembly 4 is reversed again, causing the transmission shaft 3 to move downwards. This, in turn, causes the piston 2 connected to the transmission shaft 3 to move towards the low-pressure chamber 5, and this cycle repeats continuously.

[0034] The cryogenic liquid two-stage pressurization system of the present invention uses the driving component 4 to drive the piston 2 to reciprocate within the piston chamber, so that the cryogenic liquid is initially pressurized in the low-pressure chamber 5 and then enters the high-pressure chamber 6 for secondary pressurization, thereby achieving a higher pressurization effect.

[0035] like Figure 1 , Figure 2As shown, in this embodiment, the lower end of the drive shaft 3 passes through the piston cylinder 1 and is fixedly connected to the upper end of the piston 2. The piston 2 divides the piston chamber into the upper high-pressure chamber 6 and the lower low-pressure chamber 5. The first liquid inlet passes through the bottom right side wall of the piston cylinder 1, the first liquid outlet passes through the bottom left side wall of the piston cylinder 1, the second liquid inlet passes through the top left side wall of the piston cylinder 1, and the second liquid outlet passes through the top right side wall of the piston cylinder 1. The drive assembly 4 is drivenly connected to the upper end of the drive shaft 3, driving the drive shaft 3 to reciprocate up and down along the extension direction of the piston cylinder 1. Depending on the actual application, the drive assembly 4 can adopt any drive form, as long as it can drive the drive shaft 3 to reciprocate up and down along the extension direction of the piston cylinder 1. The first one-way valve, the second one-way valve, and the third one-way valve can be... Figure 3 The one-way valve structure shown can also be any one-way valve structure. As long as the low-pressure chamber 5 is in a pressurized state, the first one-way valve and the third one-way valve are closed, and the second one-way valve opens when the low-pressure chamber 5 is pressurized to a set pressure, so that the cryogenic liquid after the initial pressurization can smoothly enter the high-pressure chamber 6. When the high-pressure chamber 6 is in a pressurized state, the first one-way valve opens, the second one-way valve closes, and the third one-way valve opens when the high-pressure chamber 6 is pressurized to a set pressure, so that the cryogenic liquid after the secondary pressurization can smoothly be discharged to the external system, and new cryogenic liquid can smoothly replenish the low-pressure chamber 5.

[0036] The cryogenic liquid can be LH2, LNG, LCO2, LN2, etc., and is stored in a liquid storage tank in an insulated cryogenic space, with the inlet pipe 7 immersed in the cryogenic liquid.

[0037] When the piston 2 moves downward, the cryogenic liquid in the low-pressure chamber 5 is initially pressurized. The required diameter of the drive shaft 3 at this time is calculated as follows:

[0038]

[0039] In the formula, d1---the minimum diameter required for the drive shaft 3 when pressed down;

[0040] F1 --- The force acting on drive shaft 3;

[0041] σ1---Allowable tensile force for the material of drive shaft 3;

[0042] Where Rm is the tensile strength of the material, and n is the safety factor.

[0043] When the piston 2 moves upward, the cryogenic liquid in the high-pressure chamber 6 is pressurized a second time. The required diameter of the drive shaft 3 at this time is calculated as follows:

[0044]

[0045] In the formula, d2 is the minimum diameter required for the drive shaft 3 when pulling upwards;

[0046] F2 --- The force acting on drive shaft 3;

[0047] σ2 --- Allowable pressure of the material of drive shaft 3;

[0048] Where, σ bc denoted as σ, where σ is the compressive strength of the material, and n is the safety factor.

[0049] Taking 304 stainless steel as an example, when d1 = d2, F2 > 5F1. This result shows that by using the aforementioned cryogenic liquid two-stage pressurization system to perform secondary compression and pressurization of cryogenic liquid, the pressurization capacity of the existing primary pressurization system can be increased by more than 5 times.

[0050] Optionally, the cross-sectional area of ​​the first end of the drive shaft 3 gradually increases in the direction toward the piston 2. This arrangement can enhance the connection strength between the drive shaft 3 and the piston 2, while reducing the volume of the high-pressure chamber 6 and decreasing the release of liquid pressure.

[0051] Because the compressibility of liquids is almost negligible, when the volume of the high-pressure chamber 6 is greater than or equal to the volume of the low-pressure chamber 5, the liquid pressure will be released. Therefore, the volume of the high-pressure chamber 6 should be appropriately reduced. Figure 1 , Figure 2 As shown, in this embodiment, the high-pressure chamber 6 is located above the piston 2. The lower end of the transmission shaft 3 has a cross-sectional area that gradually increases downwards within a certain length range near the end, forming an overall cone shape. The diameter of the cross-section at the lowest end is the same as the diameter of the cross-section of the piston 2. While increasing the contact area with the piston 2 and improving the connection strength between the two, it occupies the space inside the high-pressure chamber 6, reducing the volume of the high-pressure chamber 6.

[0052] Optionally, the volume of the high-pressure chamber 6 is set to 0.8-0.95 times the volume of the low-pressure chamber 5. This setting ensures that the volume of the high-pressure chamber 6 is large enough to guarantee the efficiency of secondary pressurization of the cryogenic liquid, while also being small enough to facilitate the release of liquid pressure and ensure the smooth progress of the secondary pressurization process. Furthermore, since the volume of the low-pressure chamber 5 is higher than that of the high-pressure chamber 6, a small amount of cryogenic liquid will remain in the low-pressure chamber 5. This avoids hard contact between the piston 2 and the bottom of the piston cylinder 1, thus achieving the function of piston steering and positioning.

[0053] Optionally, the cryogenic liquid two-stage pressurization system further includes a coaxial positioner 10, which is sleeved on the drive shaft 3 and fixedly connected to the piston cylinder 1. This arrangement improves the stability of the drive shaft 3 during movement.

[0054] like Figure 1 As shown, in this embodiment, the coaxial positioner 10 is a hollow cylinder, and its inner wall diameter matches the outer wall diameter of the drive shaft 3. The drive shaft 3 is inserted into the coaxial positioner 10 with a clearance fit, allowing the drive shaft 3 to both reciprocate along the coaxial positioner 10 and be limited by the coaxial positioner 10, preventing excessive lateral displacement. The lower end of the coaxial positioner 10 is fixedly connected to the top end of the piston cylinder 1.

[0055] Optionally, a first flange 11 is mounted on the end of the coaxial positioner 10 away from the piston cylinder 1, and the first flange 11 is fitted over the drive shaft 3. This arrangement facilitates fixing the system to other structural components using the first flange 11.

[0056] like Figure 1 As shown, in this embodiment, the upper end of the coaxial positioner 10 is fixed to the first flange 11, and the drive shaft 3 passes through the first flange 11 and the coaxial positioner 10 in sequence, and can move up and down along both. When it is necessary to fix the system to other structural components, such as fixing it inside a cryogenic liquid storage tank, the connection can be achieved by means of the preset first flange 11.

[0057] Optionally, a second flange 12 is mounted on the end of the piston cylinder 1 furthest from the coaxial positioner 10. This arrangement, in conjunction with the first flange 11, allows for a more stable fixation of the system to other structural components.

[0058] like Figure 1 As shown, in this embodiment, the lower end of the piston cylinder 1 is connected to the second flange 12. When it is necessary to fix the system in the cryogenic liquid storage tank, the connection with the cryogenic liquid storage tank can be achieved by using the preset first flange 11 and second flange 12.

[0059] Optionally, a first seal 13 is provided between the drive shaft 3 and the piston cylinder 1. This arrangement seals the connection between the drive shaft 3 and the piston cylinder 1, preventing pressure release and preventing the outflow of cryogenic liquid.

[0060] like Figure 1 As shown, in this embodiment, the first sealing member 13 is sleeved on the circumference of the transmission shaft 3 to seal the gap between the transmission shaft 3 and the piston cylinder 1, but does not affect the reciprocating movement of the transmission shaft 3.

[0061] Optionally, the drive assembly 4 includes a hydraulic cylinder 401, a hydraulic piston 402, and a hydraulic pump (not shown). The hydraulic cylinder 401 has a hydraulic chamber; the hydraulic piston 402 is disposed within the hydraulic chamber and movably connected to it, dividing the hydraulic chamber into a first chamber 403 and a second chamber 404. The side wall of the hydraulic cylinder 401 has a through-hole for connecting the first chamber 403 with a first inlet 405 and a first outlet 406, and a second inlet 407 and a second outlet 408 for connecting the second chamber 404. The first inlet 405, the first outlet 406, the second inlet 407, and the second outlet 408 are respectively connected to a four-way directional valve (not shown); the second end of the drive shaft 3 passes through the hydraulic cylinder 401, is movably connected to it, and is fixedly connected to the hydraulic piston 402; the outlet of the hydraulic pump is connected to the inlet of the four-way directional valve. Hydraulic drive is used, which is simple to operate, operates smoothly, has minimal reversing impact, and facilitates frequent reversing.

[0062] like Figure 1As shown, in this embodiment, the hydraulic cylinder 401 is fixed to the upper end of the first flange 11, and the hydraulic cylinder 401, the first flange 11, the coaxial positioner 10, and the piston cylinder 1 are coaxially arranged. Taking the first cavity 403 located above the hydraulic piston 402 and the second cavity 404 located below the hydraulic piston 402 as an example, the upper end of the transmission shaft 3 passes through the hydraulic cylinder 401 and is fixedly connected to the hydraulic piston 402 in the second cavity 404. The first inlet 405 is opened on the top right side wall of the hydraulic cylinder 401, the first outlet 406 is opened on the top left side wall of the hydraulic cylinder 401, the second inlet 407 is opened on the lower right side wall of the hydraulic cylinder 401, and the second outlet 408 is opened on the lower left side wall of the hydraulic cylinder 401. The hydraulic pump is started, allowing hydraulic oil to flow into the first cavity 403 via the pump, the four-way directional valve, and the first inlet 405. This applies pressure to the upper surface of the hydraulic piston 402, causing it to move downwards. Simultaneously, the hydraulic oil in the second cavity 404 below the piston 402 is squeezed and discharged through the second outlet 408 and the four-way directional valve to the external hydraulic oil circulation pipeline. During the downward movement of the piston 402, the drive shaft 3 and piston 2, directly or indirectly connected to it, move downwards toward the low-pressure cavity 5, achieving initial compression and pressurization of the cryogenic liquid in the low-pressure cavity 5, and then outputting the initially pressurized cryogenic liquid to the high-pressure cavity 6. After the pressure chamber 6 is filled, the four-way directional valve reverses, allowing hydraulic oil to flow into the second chamber 404 via the hydraulic pump, the four-way directional valve, and the second inlet 407. This applies pressure to the lower surface of the hydraulic piston 402, causing it to move upwards. Simultaneously, the hydraulic oil in the first chamber 403 above the hydraulic piston 402 is squeezed and discharged through the first outlet 406 and the four-way directional valve to the external hydraulic oil circulation pipeline. During the upward movement of the hydraulic piston 402, it drives the drive shaft 3 and the piston 2, which are directly or indirectly connected to it, to move upwards toward the high-pressure chamber 6. This achieves secondary compression and pressurization of the cryogenic liquid in the high-pressure chamber 6, and outputs the secondary pressurized cryogenic liquid to the external system. Using a four-way directional valve to control the flow of hydraulic oil in the corresponding hydraulic cylinder 401, causing the hydraulic piston 2 to reciprocate along the hydraulic cylinder 401, is a mature existing technology. Its specific structure and principle will not be described in detail here.

[0063] Optionally, a second seal 14 is provided between the drive shaft 3 and the hydraulic cylinder 401. This arrangement seals the connection between the drive shaft 3 and the hydraulic cylinder 401, preventing pressure release and hydraulic oil leakage.

[0064] like Figure 1 As shown, in this embodiment, the coaxial positioner 10 is fitted onto the drive shaft 3, the first flange 11 is fitted onto the drive shaft 3 and fixed above the coaxial positioner 10, the hydraulic cylinder 401 is fixed above the first flange 11, and the second seal 14 is fitted around the drive shaft 3, sealing the gap between the drive shaft 3 and the hydraulic cylinder 401, and extending along the drive shaft 3 towards the first flange 11 and the coaxial positioner 10, simultaneously sealing the gap between the drive shaft 3 and the first flange 11 and the coaxial positioner 10, without affecting the reciprocating movement of the drive shaft 3. The specific shape of the second seal 14 can be adjusted according to the actual application.

[0065] The present invention also provides a cryogenic liquid two-stage pressurization assembly, including a cryogenic liquid storage tank, and a cryogenic liquid two-stage pressurization system as described in any of the above embodiments, wherein the inlet pipe 7 of the cryogenic liquid two-stage pressurization system is immersed in the cryogenic liquid storage tank.

[0066] The cryogenic liquid two-stage pressurization assembly of the present invention uses the drive component 4 to drive the piston 2 to reciprocate within the piston chamber, so that the cryogenic liquid is initially pressurized in the low-pressure chamber 5 and then enters the high-pressure chamber 6 for secondary pressurization, thereby achieving a higher pressurization effect.

[0067] The piston cylinder 1 of the cryogenic liquid two-stage pressurization system can be fixedly connected to the inner wall of the cryogenic liquid storage tank, and the whole system can be immersed in the cryogenic liquid storage tank, with only the drive component 4 located on the outside.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cryogenic liquid two-stage pressurization system, characterized in that, include: A piston cylinder, wherein a piston chamber is provided inside the piston cylinder; A piston is disposed within a piston chamber and is movably connected to the piston chamber, dividing the piston chamber into a low-pressure chamber and a high-pressure chamber. The side wall of the piston cylinder is provided with a first inlet and a first outlet communicating with the low-pressure chamber, and a second inlet and a second outlet communicating with the high-pressure chamber. The first inlet is connected to an inlet pipe, and a first one-way valve is provided inside the inlet pipe. A connecting pipe is provided between the first outlet and the second inlet, and a second one-way valve is provided inside the connecting pipe. The second outlet is connected to an outlet pipe, and a third one-way valve is provided inside the outlet pipe. A drive shaft, the first end of which passes through the piston cylinder and is movably connected to the piston cylinder, and is fixedly connected to the piston in the high-pressure chamber. The cross-sectional area of ​​the first end of the drive shaft gradually increases in the direction toward the piston, thereby reducing the volume of the high-pressure chamber and reducing the release of liquid pressure. A drive assembly is connected to the second end of the drive shaft to drive the drive shaft to reciprocate along the piston cylinder; The volume of the high-pressure chamber is set to 0.8-0.95 times the volume of the low-pressure chamber. The volume of the high-pressure chamber is large enough to ensure the efficiency of secondary pressurization of the cryogenic liquid. At the same time, the volume of the high-pressure chamber is also small enough to facilitate the release of liquid pressure and ensure the smooth progress of the secondary pressurization process.

2. The cryogenic liquid two-stage pressurization system according to claim 1, characterized in that, Also includes: A coaxial positioner is fitted onto the drive shaft and fixedly connected to the piston cylinder.

3. The cryogenic liquid two-stage pressurization system according to claim 2, characterized in that: The coaxial positioner is equipped with a first flange at the end away from the piston cylinder, and the first flange is fitted onto the drive shaft.

4. The cryogenic liquid two-stage pressurization system according to claim 3, characterized in that: A second flange is installed at the end of the piston cylinder furthest from the coaxial positioner.

5. The cryogenic liquid two-stage pressurization system according to any one of claims 1-4, characterized in that: A first seal is provided between the drive shaft and the piston cylinder.

6. The cryogenic liquid two-stage pressurization system according to any one of claims 1-4, characterized in that, The driving component includes: A hydraulic cylinder, wherein a hydraulic chamber is provided inside the hydraulic cylinder; A hydraulic piston is disposed within and movably connected to the hydraulic chamber, dividing the hydraulic chamber into a first chamber and a second chamber. A first inlet and a first outlet communicating with the first chamber, and a second inlet and a second outlet communicating with the second chamber are provided through the side wall of the hydraulic cylinder. The first inlet, first outlet, second inlet, and second outlet are respectively connected to a four-way directional valve. The second end of a drive shaft passes through the hydraulic cylinder, is movably connected to the hydraulic cylinder, and is fixedly connected to the hydraulic piston. A hydraulic pump, wherein the outlet of the hydraulic pump is connected to the inlet of the four-way directional valve.

7. The cryogenic liquid two-stage pressurization system according to claim 6, characterized in that: A second seal is provided between the drive shaft and the hydraulic cylinder.

8. A cryogenic liquid two-stage pressurization assembly, comprising a cryogenic liquid storage tank, characterized in that, It also includes the cryogenic liquid two-stage pressurization system according to any one of claims 1-7, wherein the inlet pipe of the cryogenic liquid two-stage pressurization system is immersed in the cryogenic liquid storage tank.

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