Methods and apparatus for hydrogen pumping and compression
The two-stage pumping and compression device with independently operating stages addresses inefficiencies in hydrogen refueling by optimizing the first and second stage pumps' operations, achieving efficient hydrogen transfer and reducing losses.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- FIRSTELEMENT FUEL INC
- Filing Date
- 2024-03-15
- Publication Date
- 2026-04-10
AI Technical Summary
Existing hydrogen refueling systems face inefficiencies due to the first stage pump operating at a mass flow rate that exceeds the capacity of the second stage pump, resulting in excess exhaust gas, as both stages are mechanically coupled.
A two-stage pumping and compression device with independently operating stages, where the first stage pump operates slowly on demand and the second stage pump operates at a high speed to maximize capacity while minimizing physical size, with optional buffer volumes to manage flow discrepancies.
This configuration allows for efficient transfer of liquid hydrogen to a gaseous state with minimal pressure loss, enabling faster refueling and reducing hydrogen loss during transport, while allowing for a more efficient design of the second pumping stage.
Smart Images
Figure 2026510903000001_ABST
Abstract
Description
Technical Field
[0001]
[0001] The present invention generally relates to the handling of fuels, and more specifically, to an apparatus and method for pumping cryogenic hydrogen.
Background Art
[0002]
[0002] Hydrogen filling stations for vehicles typically store large amounts of hydrogen as a liquid at a pressure of 1 to 6 bar and a temperature of 18 to 25 K (Note: Unless otherwise specified, the pressures described are absolute pressures. When "barg" is used, this refers to gauge pressure in bar units). To be dispensed to vehicles fueled by hydrogen, the hydrogen must transition to a gaseous state at a high pressure of at least 350 barg, for example, 900 to 950 barg and a temperature of -40 to -30 degrees Celsius (233 to 243 K).
[0003]
[0003] To effect this transition, a pumping and heating sequence is required. In the prior art, a two-stage process has been found to be effective, but this process is typically limited by the physical constraints of the liquid hydrogen entering the first stage of the pumping system. Since liquid hydrogen vaporizes with only a small energy input or pressure decrease as occurs when a valve is throttled, a gravity supply to the first pumping stage or subcooling stage is used. Further, due to constraints on minimal heat transfer to the system, the first and second pumping stages are typically connected to the same drive rod.
Summary of the Invention
Problems to be Solved by the Invention
[0004]
[0004] One problem with this type of apparatus is that by mechanically coupling these stages, the first stage pump operates at a mass flow rate that exceeds the capacity of the second stage pump. This results in inefficiencies due to excess exhaust gas.
Means for Solving the Problems
[0005]
[0005] This problem is addressed by a two-stage pumping and compression device having independently operating stages.
[0006]
[0006] The present invention can be best understood by referring to the following description made in conjunction with the accompanying drawings. [Brief explanation of the drawing]
[0007] [Figure 1]
[0007] This is a schematic diagram of a hydrogen refueling station. [Figure 2]
[0008] This is a schematic diagram of the pump and compressor system. [Figure 3]
[0009] This is a schematic diagram of the initial configuration of a pump and compressor system with multiple low-pressure pumps. [Figure 4]
[0010] Figure 3 is a schematic diagram of the subsequent pump and compressor system. [Figure 5]
[0011] Figure 6 is a schematic diagram of the subsequent pump and compressor system. [Figure 6]
[0012] Figure 2 is a schematic diagram of the pump and compressor system configured for liquid hydrogen transfer. [Modes for carrying out the invention]
[0008]
[0013] Referring to the drawings, Figure 1 shows a hydrogen refueling station 10 that works in conjunction with a vehicle 12. The vehicle 12 includes a gaseous fuel storage tank 14 equipped with a refueling port 16.
[0009]
[0014] It should be noted that the use of vehicle 12 is merely an illustrative example, and the apparatus and methods described herein are suitable for application to any cryogenic storage system.
[0010]
[0015] The refueling station 10 includes a large-volume fuel (e.g., hydrogen) storage tank 18. In an exemplary embodiment, the large-volume fuel is stored as a liquid. The fuel is ultimately distributed in gaseous form through a nozzle 20 located at the distal end of a refueling hose 22 and configured to connect to a refueling port 16. To enable faster refueling of vehicles, there is a prepared storage tank 24 in which hydrogen is stored as a high-pressure gas.
[0011]
[0016] It will be understood that this type of filling station 10 may include conventional auxiliary equipment for handling fuel, such as heat exchangers, pumps, compressors, and / or valves and their associated controllers.
[0012]
[0017] The filling station 10 includes at least one control device that can operate to influence some aspect of the gaseous fuel flow. An example of a control device is a controllable valve schematically shown by reference numeral 26. This may be, for example, a flow measuring valve.
[0013]
[0018] The filling station 10 includes a pumping and compression device 100 for transferring liquid hydrogen at a pressure of 1 to 6 bar and a temperature of 18 to 25 K from a large storage tank 18 to a prepared storage tank 24 in a gaseous state at a high pressure of 350 to 950 barg and a temperature of -40 to -30 degrees Celsius (233 to 243 K) or higher. Figure 2 shows an exemplary pumping and compression device 100 suitable for this purpose.
[0014]
[0019] It will be understood that the operating components of apparatus 100 are interconnected along flow paths defined by piping or tubing suitable for the flow of pressurized liquid and / or gaseous hydrogen. In the drawings, piping connections are depicted by a single solid line, and data and / or control connections are depicted by a single dashed line. As used herein, the term “pipe” may refer to any conduit suitable for the flow of an intended fluid, such as pipes, hoses, tubes, or manifolds, which may have various sizes and cross-sectional shapes and may be made from an assembly of components, such as pipe segments, connectors, and / or fittings.
[0015]
[0020] The apparatus 100 includes a first stage pump 102 and a second stage pump 104 in succession in flow order.
[0016]
[0021] The first stage pump 102 is a positive displacement pump having a chamber 106 with an inlet port 108 and an outlet port 110. A pump element 112 is positioned in the chamber 106 and is movable between first and second positions, i.e., along the suction stroke and discharge stroke. In the illustrated embodiment, the pump element 112 includes a piston 114 coupled to a piston rod 116 and sealed to the wall of the chamber 106 by a suitable sliding contact seal 118. It will be understood that other types of positive displacement chamber and pump element combinations may be used instead of the linear piston-cylinder device shown.
[0017]
[0022] The pump element 112 is coupled to a first stage driver 120. The first stage driver 120 may be any mechanism suitable for moving the pump element 112 at a variable speed. Non-limiting examples of suitable drivers include a hydraulic circuit, an electromagnetic system, or a direct mechanical connection. In the illustrated embodiment, the first stage driver 120 is an electric ball screw. Note that the ball screw driver may be used to drive any type of pump for cryogenic materials.
[0018]
[0023] The inlet valve 122 is positioned at or near the inlet port 108. Various types of valves may be used, but it is preferable to use a valve that does not cause a pressure drop to be held in the open position (such as the situation when using a conventional check valve). An example of such a valve is an actuator-driven valve, where an actuator 123 such as a solenoid operates a physical valve element inside the inlet valve 122.
[0019]
[0024] The transfer pipe 124 interconnects the first and second stage pumps 102, 104. More specifically, the transfer pipe 124 is connected to fluidly communicate with the outlet port 110 of the first stage pump 102 and the inlet port 138 of the second stage pump 104.
[0020]
[0025] Optionally, as will be described in more detail below, the first stage pump 102 may be used to transfer (pump) liquid hydrogen from the dispensing vehicle to the bulk storage tank 18. To enable this function, the transfer pipe 124 interconnecting the first and second stage pumps 102, 104 may be coupled to the outlet port 110 by a T-joint 126 and may include first and second shut-off valves 128, 130 that may be operated manually or remotely, and may include an outlet check valve 132. Optionally, the second shut-off valve 130 may be an actuated valve, such as a solenoid-driven valve. The first and second shut-off valves 128, 130 may be selectively configured to send the flow from the first stage pump 102 to the second stage pump 104 or to the bulk storage tank 18.
[0021]
[0026] A pressure transducer 134 is coupled downstream of the first stage pump 102. The pressure transducer 134 is operable to sense the hydrogen pressure and generate a signal representative thereof.
[0022]
[0027] The second stage pump 104 is a positive displacement pump having a chamber 136 with an inlet port 138 and an outlet port 140. A discharge check valve 142 is located at or near the outlet port 140. A pump element 144 is disposed within the chamber 136 and is movable between a first and second position, i.e., along an intake stroke and a discharge stroke. In the illustrated embodiment, the pump element 144 is a piston 14, sealed by a suitable sliding contact seal 148 to the wall of the chamber 136. The piston 146 includes an internal bore 150 extending from a transfer port 152 located in the sidewall of the piston 146 to an internal check valve 154 located at the lower end 156. It will be appreciated that other combinations of positive displacement chambers and pump elements may be used in place of the illustrated linear piston-cylinder device.
[0023]
[0028] The pump element 144 is coupled to a second stage driver 158. The second stage driver 158 may be any mechanism suitable for moving the pump element 144 at a variable speed. Non-limiting examples of suitable drivers include hydraulic circuits, electromagnetic systems, or direct mechanical couplings. In the embodiment shown, the second stage driver 158 may be an electric motor 160 coupled to the piston 146 by a mechanical coupling 162.
[0024]
[0029] The piping between the first stage pump 102 and the second stage pump 104 may incorporate a buffer volume section 164. This may be selectively vented to the atmosphere or a large steam storage space through a vent valve 166.
[0025]
[0030] The apparatus 100 includes a first stage driver 120 and a second stage driver 158, as well as means for controlling various valves of the system. In the embodiment shown, the control means comprises an electronic controller 168. The controller 168 includes one or more processors capable of executing ladder logic, programmed instructions, or some combination thereof. For example, the controller 168 may be a known type of general-purpose microcomputer, such as a PC-based computer, or a custom processor, or may incorporate one or more programmable logic controllers (PLCs).
[0026]
[0031] The controller 168 receives a hydrogen pressure input from the pressure transducer 134. The controller 168 is operable to control the first stage driver 120, the second stage driver 158, and the inlet valve 122 of the first stage (if an operating valve is used).
[0027]
[0032] The device 100 is operated by a first stage pump 102, driven by its first stage driver 120, to reciprocate, drawing liquid hydrogen from the large fuel storage tank 18 as a liquid at approximately 18-25 K and 1-6 bar, and discharging it as a liquid at approximately 20-30 K and 2-20 bar. If an operating inlet valve is used, during operation, its inlet valve 122 is operated by command to open during the intake stroke and close during the discharge stroke. By utilizing this valve method, the liquid hydrogen experiences virtually no pressure drop at the inlet valve 122.
[0028]
[0033] Simultaneously, the second stage pump 104 is reciprocated by its second stage driver 158 to take in liquid hydrogen from the first stage pump 102, compress the liquid hydrogen into a gas at approximately 45-70K and at least 350 bar, for example, 900 bar, and discharge it to the prepared storage tank 24 of the replenishment station 10.
[0029]
[0034] During this operation, the first and second stage pumps 102 and 104 operate independently. The second stage pump 104 may be operated at a relatively high speed to maximize its capacity while minimizing its physical size.
[0030]
[0035] The first stage pump 102 may be operated slowly and on demand in response to the mass flow rate of the second stage pump 104. By operating on demand, the first stage pump 102 (alternatively called the subcooling stage) does not need to pump more hydrogen than is required. The piston 114 may have its diameter increased as needed to maintain mass flow capacity. For example, the first stage pump 102 may have a stroke volume approximately three to four times that of the second stage pump 104. The resulting utility is the ability to operate the first stage slowly, particularly in the reverse stroke, to facilitate a smooth laminar flow supply.
[0031]
[0036] The control of the first stage pump 102 may be carried out in various ways. In one example, a pressure output target for the first stage is specified. The controller 168 then uses feedback signals from the pressure transducer 134 to operate the driver 120 as needed to maintain the target pressure. For example, the driver speed may be increased to increase the pressure, or decreased to decrease the pressure (or even stopped).
[0032]
[0037] Optionally, driver 120 (or any of the other first stage drivers described herein) may be used to dynamically change the stroke volume of the first stage pump. For example, the first stage pump may have a maximum physical stroke volume much larger than that of the second stage pump, such as a 50:1 ratio. In operation, the driver may be actuated to move the piston over a desired portion of its maximum possible stroke. Thus, the real-time stroke volume of the first stage pump can be anywhere between 1 and 50 times the stroke volume of the second stage pump.
[0033]
[0038] Optionally, (if present) a buffer volume section 164 may be used to absorb any difference in displacement between the first and second stage pumps 102, 104 that may arise from a slight mismatch in volumetric flow rates. This is most likely to occur during operational transients, such as when changing the output pressure of the second stage pump 104. This buffer volume section may be ventilated as needed to maintain the correct pressure. This volume section may also act as a receptacle for any bubbles that may be generated from the first stage pump 102.
[0034]
[0039] Optionally, multiple first stage pumps may be used to supply one or more groups of second stage pumps. In one example, a group of three first stage pumps is used to drive two second stage pumps. The use of multiple first stage pumps ensures an adequate flow capacity for supplying the second stage pumps. In the embodiment illustrated in Figures 3 to 5, the three first stage pumps labeled 102A, 102B, and 102C all discharge into a common piping stroke, as well as the transfer pipe 124, to supply the second stage pump 104. Each of the three first stage pumps 102A, 102B, and 102C is equipped with its own independently controlled driver as described above. These drivers may operate sequentially to provide a smooth flow output while minimizing piston speed, particularly in the suction stroke.
[0035]
[0040] In Figure 3, pump 102A is shown moving downward at baseline speed towards the end of the discharge stroke, as indicated by the arrow. Pump 102B is approaching the end of the suction stroke, as indicated by the arrow. During this suction stroke, pump 102B may operate at a reduced speed, for example, half the baseline speed. Pump 102C is near the middle of the suction stroke, as indicated by the arrow. During this suction stroke, pump 102C may operate at a reduced speed, for example, half the baseline speed.
[0036]
[0041] Figure 4 illustrates the pumps at a later time than those illustrated in Figure 3. Pump 102A is beginning its suction stroke, as indicated by the arrow, and is moving upward at a speed less than the baseline speed. Pump 102B is moving downward at the baseline speed in its discharge stroke, as indicated by the arrow. Pump 102C is near the end of its suction stroke, as indicated by the arrow. During this suction stroke, pump 102C may be operating at a reduced speed, for example, half the baseline speed.
[0037]
[0042] Figure 5 illustrates the pumps at a later time than those illustrated in Figure 4. Pump 102A is partially in its suction stroke, as indicated by the arrow, moving upward at a speed less than the baseline speed. Pump 102B has finished its discharge stroke, as indicated by the arrow, and is moving upward in the suction stroke. During this suction stroke, pump 102B may operate at a reduced speed. Pump 102C has begun its discharge stroke, as indicated by the arrow. During this discharge stroke, pump 102C may operate at the baseline speed.
[0038]
[0043] This cycle may be continued, with each pump alternately discharging at a baseline speed and retracting at a reduced speed. The net effect is to provide an extremely uniform fluid flow rate while minimizing piston speed.
[0039]
[0044] In an alternative configuration, two or more first stage pumps, as illustrated in Figure 3, may be used and controlled independently in a dynamic sequence rather than a static sequence. For example, if two first stage pumps are used, one of them may be operated at a variable speed. This may be useful in situations where one of the first stage pumps is nearing the end of its discharge cycle, but additional flow is needed to meet the requirements of the second stage pump. In such situations, an independent controller may be used to accelerate the discharge stroke of the other first stage pump, so that it "catches up" with the cycle of the other first stage pump, and to ensure that the second stage pump is supplied with adequate flow.
[0040]
[0045] Another possible use for the device 100 is truck unloading. Conventionally, hydrogen is transported to the hydrogen refueling station 10 in a transport container (circularly illustrated by reference numeral 200 in Figure 6). The transport container 200 may be, for example, a tank mounted on a truck or rail vehicle.
[0041]
[0046] Typically, hydrogen is stored in a transport container 200 as a liquid at 18–25 K and approximately 1.4 bar. In the prior art, a high-temperature process called pressure rise is used to generate a sufficient pressure difference to push the liquid hydrogen from the transport container 200 to the replenishment station 10. During this process, a considerable amount of hydrogen is vented to the atmosphere to relieve the pressure in the transport container following the transfer. Analysis has shown that if device 100 were used for this purpose, the pressure in the transport container would remain low, allowing device 100 to transfer liquid hydrogen with high efficiency, thus achieving enormous savings in the amount of hydrogen lost.
[0042]
[0047] Referring to Figure 6, in order to enable this function, the transport container 200 is coupled to the inlet port 108. The first shut-off valve 128 is closed and the second shut-off valve 130 is opened.
[0043]
[0048] Next, in a manner similar to that described above, the first stage pump 102 is operated by the first stage driver 120 to move liquid hydrogen from the transport container 200 to the large storage tank 18 as liquid at approximately 18-25K and approximately 0.27-2.5 bar. The hydrogen flow path is from the transport container 200, through the inlet valve 122, pump 102, first shut-off valve 128, and outlet check valve 132, finally reaching the large storage tank 18. The second stage pump 104 is not used. Alternatively, in a configuration where both the inlet valve 122 and the second shut-off valve 130 are operating valves, they may be operated cyclically in sync with the operation of the first stage pump element 112. For example, the inlet valve 122 is opened and the second shut-off valve 130 is closed during the intake stroke, and the inlet valve 122 is closed and the second shut-off valve 130 is opened during the discharge stroke. In this configuration, the outlet check valve 132 is eliminated. This configuration can reduce or eliminate pressure loss in the valve during pumping operation.
[0044]
[0049] The pump configuration in Figure 6 may optionally be used to directly transfer liquid hydrogen from a large storage tank 18 to a vehicle (not shown) that uses hydrogen as fuel in liquid form up to a pressure of 16 bar. To achieve this transfer, the large storage tank 18 is coupled to the inlet valve 122 in Figure 6, and the vehicle (e.g., vehicle 12 in Figure 1) is coupled to the outlet check valve 132 in Figure 6.
[0045]
[0050] This device has certain advantages. The first-stage pump, which can operate slowly on demand and subcool the hydrogen supplied from the liquid tank by pressurizing the liquid to a range of 8-10 barg, allows for a more efficient design of the second pumping stage for high pressure. One clear advantage is that it facilitates faster operating speeds for the second stage while removing excess pumping from the first stage. Another clear advantage is the ability to direct the discharge from the first stage to different destinations.
[0046]
[0051] While incorporating an independent driver may reduce the system's thermal efficiency compared to conventional pumps with coupled stages, the properties of the low-pressure subcooling chamber allow for reduced material stiffness, thus enabling highly efficient thermal separation. In particular, the structural load on the pump rod in the first-stage pump is significantly smaller than that of the second-stage pump, allowing for a lighter structure. Similarly, by eliminating the bidirectional load of conventional two-stage pump drives, the load on the second-stage pump 104 can be entirely shifted to a unidirectional load (i.e., compression only or extension only), which allows for structural reconfiguration to improve thermal separation efficiency.
[0047]
[0052] The foregoing describes hydrogen pressurization and compression apparatus and methods. All of the features disclosed herein (including any appended claims, abstract and drawings) and / or all of the steps of any method or process disclosed herein may be combined in any combination, except for any combination in which at least some of such features and / or steps are mutually exclusive.
[0048]
[0053] Each feature disclosed herein (including any attached claims, abstract, and drawings) may be replaced by an alternative feature serving the same, equivalent, or similar purpose, unless otherwise expressly stated. Thus, unless otherwise expressly stated, each disclosed feature is merely an example of a general set of equivalent or similar features.
[0049]
[0054] The present invention is not limited to the details of the embodiments described above. The present invention extends to any novel features or any novel combination of features disclosed herein (including any appended claims, abstract and drawings), or any novel methods or steps of processes disclosed herein.
Claims
1. A hydrogen pumping and compression device, A positive displacement first stage pump, including a pump element positioned in a pump chamber having an inlet port and an outlet port, A first stage driver coupled to the pump element, An inlet valve that communicates with the inlet port of the first stage pump, A positive displacement second stage pump, including a pump element positioned in a pump chamber having an inlet port and an outlet port, A second stage driver coupled to the pump element of the second stage pump, A hydrogen pumping and compression apparatus comprising a transfer pipe that interconnects the outlet port of the first stage pump and the inlet port of the second stage pump.
2. The transfer pipe communicates with the buffer volume section, The hydrogen pumping and compression apparatus according to claim 1, wherein the buffer volume section includes a vent valve that communicates with the atmosphere or a large-capacity steam storage space.
3. The hydrogen pumping and compression apparatus according to claim 1, wherein the inlet valve is operated by an actuator.
4. The hydrogen pumping and compression apparatus according to claim 3, further comprising the first stage driver, the second stage driver, and an electronic controller operably connected to the inlet valve.
5. The hydrogen pumping and compression apparatus according to claim 1, further comprising a pressure transducer located downstream of the first stage pump, the pressure transducer being operable to sense hydrogen pressure and generate a signal representing it, and being operably connected to an electronic controller operably connected to the first stage driver and the second stage driver.
6. The hydrogen pumping and compression apparatus according to claim 1, wherein the first stage pump has a stroke volume that can be varied in a ratio of 1:1 to 50:1 with respect to the stroke volume of the second stage pump.
7. The system includes two or more positive displacement first stage pumps, each of which includes a pump element positioned in a pump chamber having an inlet port and an outlet port. The hydrogen pumping and compression apparatus according to claim 1, wherein the transfer pipe interconnects the outlet ports of the two or more positive displacement first stage pumps to the inlet ports of the second stage pumps.
8. The hydrogen pumping and compression apparatus according to claim 1, wherein the transfer pipe is connected to the outlet port of the first stage pump by a T-joint and comprises first and second shut-off valves, the first and second shut-off valves being selectively configured to deliver the flow from the first stage pump to the second stage pump, or to a storage tank, or to a vehicle that directly receives liquid hydrogen as fuel.
9. A method for hydrogen pressurizing and compressing, To extract hydrogen from a large fuel storage tank as a liquid at a temperature of 18–25K and a pressure of 1–6 bar, and to discharge it as a liquid at a temperature of 20–30K and a pressure of 2–20 bar, a first stage driver is used to operate a positive displacement first stage pump. A hydrogen pumping and compression method comprising simultaneously operating a positive displacement second stage pump using a second stage driver independent of the first stage driver to extract liquid hydrogen from the first stage pump, compress it into a gas at a temperature of 45-70K and a pressure of at least 350 bar, and discharge it into a prepared storage tank.
10. The hydrogen pumping and compression method according to claim 9, wherein the first stage pump has a stroke volume that changes during operation at a ratio of 1:1 to 50:1 with respect to the stroke volume of the second stage pump.
11. The hydrogen pumping and compression method according to claim 9, wherein the liquid hydrogen is transferred from the first stage pump to the second stage pump through a transfer pipe having a buffer volume section.
12. The pressure of the liquid hydrogen in the buffer volume section is monitored, The hydrogen pumping and compression method according to claim 11, further comprising: in response to the pressure exceeding a predetermined value, venting some of the liquid hydrogen through a vent valve to the atmosphere or a large storage vapor space in order to reduce the pressure.
13. The hydrogen pumping and compression method according to claim 9, further comprising using an electronic controller to control the first stage driver and the second stage driver.
14. A pressure transducer located downstream of the first stage pump is used to sense the hydrogen pressure, The hydrogen pumping and compression method according to claim 13, further comprising using a feedback signal from the pressure transducer to operate the first stage driver as necessary to maintain a target pressure.
15. The hydrogen pumping and compression method according to claim 9, wherein two or more of the positive displacement first stage pumps are operated, each having its own first stage driver for drawing hydrogen from the large fuel storage tank as a liquid at a temperature of 18 to 25 K and a pressure of 1 to 6 bar, and discharging it as a liquid at a temperature of 20 to 30 K and a pressure of 2 to 20 bar.
16. The hydrogen pumping and compression method according to claim 15, wherein each of the first stage pumps discharges at a baseline speed and retracts at a reduced speed.
17. The hydrogen pumping and compression method according to claim 9, wherein the hydrogen is introduced into the first stage pump through an inlet valve operated by an actuator.