Method and apparatus for hydrogen pumping and compression

Abstract

The hydrogen pumping and compression device includes: a positive displacement first stage pump including a pump element disposed in a pump chamber having an inlet port and an outlet port; a first stage driver coupled to the first pump element; an inlet valve in flow communication with the inlet port of the first stage pump; a positive displacement second stage pump comprising a pump element disposed in a pump chamber having an inlet port and an outlet port; a second stage driver coupled to a pump element of the second stage pump; and a transfer line interconnecting the outlet port of the first stage pump with the inlet port of the second stage pump.

Description

Technical Field

[0001] The present invention relates generally to fuel processing, and more specifically to apparatus and methods for pumping cryogenic hydrogen. Background Technology

[0002] Hydrogen refueling stations for vehicles typically store large quantities of hydrogen as a liquid at pressures of 1–6 bar and temperatures of 18–25 K. (Note: Unless otherwise specified, the claimed pressure is absolute. When used, “barg” refers to gauge pressure in bars.) For hydrogen to be dispensed into hydrogen-fueled vehicles, it must be converted to a gaseous state at a pressure of at least 350 barg (e.g., 900 to 950 barg) and a temperature of -40 to -30°C (233 to 243 K).

[0003] To achieve this transition, a series of pumping and heating processes are required. In the prior art, two-stage processes have proven effective; however, such processes are typically limited by the physical constraints of the liquid hydrogen entering the first stage of the pumping system. Since liquid hydrogen evaporates only with minimal energy input or pressure reduction, such as when passing through a valve throttling process, gravity supply to the first pumping stage or subcooled stage is employed. Furthermore, due to constraints on minimum heat transfer into the system, the first and second pumping stages are typically connected to the same drive rod.

[0004] One problem with this type of device is that the mechanical connection of the stages causes the first-stage pump to operate at a mass flow rate exceeding the capacity of the second-stage pump. This results in low efficiency due to excessive discharge. Summary of the Invention

[0005] This problem is solved by a two-stage pumping and compression device with independently operating stages. Attached Figure Description

[0006] The invention can be best understood by referring to the following description in conjunction with the accompanying drawings, in which:

[0007] Figure 1 This is a schematic diagram of a hydrogen filling station;

[0008] Figure 2 This is a schematic diagram of a pump and compressor unit;

[0009] Figure 3 This is a schematic diagram of a pump and compressor unit with multiple low-pressure pumps at the first moment;

[0010] Figure 4 yes Figure 3 A schematic diagram of the pump and compressor unit in subsequent time.

[0011] Figure 5 yes Figure 6 A schematic diagram of the pump and compressor unit at a later time; and

[0012] Figure 6 It is configured for liquid hydrogen transfer. Figure 2 A schematic diagram of the pump and compressor unit. Detailed Implementation

[0013] Refer to the attached diagram. Figure 1 A hydrogen refueling station 10 integrated with vehicle 12 is shown. Vehicle 12 includes a gaseous fuel storage tank 14 equipped with a filling container 16.

[0014] Please note 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.

[0015] Filling station 10 includes bulk fuel (e.g., hydrogen) storage tanks 18. In the example shown, the bulk fuel is stored as a liquid. The fuel is ultimately dispensed in gaseous form via nozzle 20, which is located at the distal end of filling hose 22 and configured for connection to filling container 16. To allow for faster vehicle refueling, a ready storage tank 24 is provided, in which hydrogen is stored as a high-pressure gas.

[0016] It should 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 controls.

[0017] The filling station 10 includes at least one control device operable to influence some aspect of the gaseous fuel flow. An example of the control device is a controllable valve schematically shown as "26". For example, the controllable valve could be a flow metering valve.

[0018] The filling station 10 includes a pumping and compression device 100 for transferring hydrogen from a liquid state in a bulk storage tank 18 at a pressure of 1-6 bar and a temperature of 18-25 K to a gaseous state in a ready storage tank 24 at a pressure of 350-950 barg and a temperature of -40-30°C (233-243 K) or higher. Figure 2 An exemplary pumping and compression device 100 suitable for this purpose is shown.

[0019] It should be understood that the operating components of device 100 are interconnected along flow paths defined by conduits or pipes suitable for flowing pressurized liquid and / or gaseous hydrogen. In the accompanying drawings, conduit connections are depicted by a single solid line, while data and / or control connections are depicted by a single dashed line. As used herein, the term "pipe" can refer to any conduit suitable for flowing a desired fluid, such as a fitting, hose, pipe, or manifold; these conduits may have different dimensions and cross-sectional shapes and may consist of assemblies including components such as pipe sections, couplings, and / or fittings.

[0020] The device 100 includes a first-stage pump 102 and a second-stage pump 104 in a series flow sequence.

[0021] The first-stage pump 102 is a positive-displacement pump (positive displacement pump) with a chamber 106 having an inlet port 108 and an outlet port 110. A pump element 112 is disposed within the chamber 106 and is movable between a first position and a second position, i.e., along the suction stroke and the discharge stroke. In the example shown, the pump element 112 includes a piston 114 coupled to a piston rod 116 and sealed to the wall of the chamber 106 using a suitable sliding contact seal 118. It should be understood that other types of positive-displacement chamber and pump element combinations may replace the linear piston-cylinder assembly shown.

[0022] Pump element 112 is coupled to a first-stage driver 120. The first-stage driver 120 can be any mechanism suitable for moving pump element 112 at a variable speed. Non-limiting examples of suitable drivers include hydraulic circuits, electromagnetic systems, or direct mechanical linkages. In the example shown, the first-stage driver 120 is an electric ball screw. Note that a ball screw driver can be used to drive any type of pump for cryogenic materials.

[0023] Inlet valve 122 is located at or near inlet port 108. Although various types of valves can be used, it is preferable to use a valve that does not introduce a pressure drop so that it can be held in the open position (e.g., in the case of a conventional check valve). An example of such a valve is an actuator-operated valve, in which an actuator 123, such as a solenoid, operates a physical valve element located inside inlet valve 122.

[0024] Delivery line 124 interconnects the first-stage pump 102 and the second-stage pump 104. More specifically, delivery line 124 is in flow communication with the outlet port 110 of the first-stage pump 102 and the inlet port 138 of the second-stage pump 104.

[0025] Optionally, the first-stage pump 102 can be used to transfer (pump) liquid hydrogen from the transport vehicle to the bulk storage tank 18, as described in more detail below. To achieve this function, a delivery line 124 interconnecting the first-stage pump 102 and the second-stage pump 104 can be connected to the outlet port 110 via a tee (T-joint) 126, and is respectively equipped with a first shut-off valve 128 and a second shut-off valve 130, as well as an outlet check valve 132, which can be operated manually or remotely. Optionally, the second shut-off valve 130 can be an actuated valve such as a solenoid-operated valve. The first shut-off valve 128 and the second shut-off valve 130 can be selectively configured to direct flow from the first-stage pump 102 to the second-stage pump 104 or to the bulk storage tank 18.

[0026] Pressure sensor (transducer) 134 is connected downstream of the first-stage pump 102. Pressure sensor 134 is operable to sense hydrogen pressure and generate a signal representing the hydrogen pressure.

[0027] The second-stage pump 104 is a positive-displacement pump (positive displacement pump) with a chamber 136 having 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 position and a second position, i.e., along the suction stroke and the discharge stroke. In the example shown, the pump element 144 is a piston 146 sealed to the wall of the chamber 136 by a suitable sliding contact seal 148. The piston 146 includes an inner bore 150 extending from a delivery port 152 located on the side wall of the piston 146 to an internal check valve 154 located at the lower end 156. It should be understood that other types of positive displacement chamber and pump element combinations may replace the linear piston cylinder assembly shown.

[0028] Pump element 144 is coupled to a second-stage drive 158. The second-stage drive 158 can be any mechanism adapted to move pump element 144 at a variable speed. Non-limiting examples of suitable drives include hydraulic circuits, electromagnetic systems, or direct mechanical linkages. In the example shown, the second-stage drive 158 can be an electric motor 160 coupled to piston 146 via a mechanical link 162.

[0029] The pipeline between the first-stage pump 102 and the second-stage pump 104 can be combined with a buffer volume 164. This can be selectively discharged to the atmosphere or a bulk (large-capacity) vapor storage space via an exhaust valve 166.

[0030] The device 100 includes means for controlling the first-stage driver 120, the second-stage driver 158, and various valves in the system. In the example shown, the control means includes 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, it may be a general-purpose microcomputer of a known type, such as a PC-based computer, or it may be a custom processor, or it may be combined with one or more programmable logic controllers (PLCs).

[0031] The controller 168 receives hydrogen pressure input from the pressure sensor 134. The controller 168 is operable to control the first-stage actuator 120, the second-stage actuator 158, and the first-stage inlet valve 122 (if an actuated valve is used).

[0032] The device 100 is operated by reciprocating a first-stage pump 102 via its first-stage driver 120 to draw liquid hydrogen from the bulk fuel storage tank 18 as a liquid at approximately 18-25 K and 1-6 bar, and to discharge it as a liquid at approximately 20-30 K and 2-20 bar. If an actuated inlet valve is used, its inlet valve 122 will be commanded to open during the suction stroke and close during the discharge stroke during operation. By utilizing this valve configuration, the liquid hydrogen will experience a near-zero pressure drop at the inlet valve 122.

[0033] Meanwhile, the second-stage pump 104 reciprocates via its second-stage driver 158 to obtain liquid hydrogen from the first-stage pump 102, compress it into a gas at approximately 45-70 K and at least 350 bar (e.g., 900 bar), and discharge it to the ready storage tank 24 of the refill station 10.

[0034] During this operation, the first-stage pump 102 and the second-stage pump 104 operate independently. The second-stage pump 104 can be actuated at a relatively high speed to minimize its physical size while maximizing its capacity.

[0035] The first-stage pump 102 can be slowly actuated in response to the mass flow rate of the second-stage pump 104 as needed. By driving as needed, the first-stage pump 102 (optionally referred to as the subcooled stage) does not need to pump more hydrogen than required. The diameter of the piston 114 can be increased as needed to maintain the mass flow capacity. For example, the swept volume of the first-stage pump 102 can be approximately 3 to 4 times the swept volume of the second-stage pump 104. The benefit obtained is the ability to slowly actuate the first stage, especially during the retraction stroke, to promote a smooth laminar feed.

[0036] The first-stage pump 102 can be controlled in various ways. In one example, a target pressure output for the first stage will be specified. Subsequently, the controller 168 will use feedback signals from the pressure sensor 134 to operate the driver 120 as needed to maintain the target pressure. For example, the driver speed can be increased to increase the pressure, or the driver speed can be decreased (or even stopped) to decrease the pressure.

[0037] Optionally, the driver 120 (or any other first-stage driver described herein) can be used to dynamically change the sweep volume of the first-stage pump. For example, the maximum physical sweep volume of the first-stage pump can be much larger than the maximum physical sweep volume of the second-stage pump, such as a ratio of 50 to 1. In operation, the driver can be actuated to move the piston to a desired portion of the maximum possible stroke. In this way, the real-time sweep volume of the first-stage pump can be 1 to 50 times that of the real-time sweep volume of the second-stage pump.

[0038] Optionally, a buffer volume 164 (if present) can be used to absorb any differential displacement between the first-stage pump 102 and the second-stage pump 104, which may be caused by a slight mismatch in volumetric flow rates. This is likely to occur during transient operation, such as when the output pressure of the second-stage pump 104 is changed. The buffer volume can be discharged as needed to maintain the correct pressure. The volume can also be used as a trap for any bubbles that may be generated from the first-stage pump 102.

[0039] Optionally, multiple first-stage pumps can be used to supply a group of second-stage pumps, including one or more second-stage pumps. In one example, a group of three first-stage pumps would be used to drive two second-stage pumps. Using multiple first-stage pumps ensures sufficient flow capacity to supply the second-stage pumps. Figures 3 to 5 In the example shown, the three first-stage pumps, labeled 102A, 102B, and 102C, all discharge into a common piping run (similar to delivery line 124) to supply the second-stage pump 104. As described above, each of these first-stage pumps 102A, 102B, and 102C is equipped with its own independently controlled driver. These first-stage pumps 102A, 102B, and 102C are capable of operating sequentially to provide a smooth flow output while minimizing piston speed (especially during the suction stroke).

[0040] exist Figure 3In the diagram, pump 102A is shown at the end of the discharge stroke, moving downwards at the baseline speed 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 can operate at a reduced speed (e.g., half the baseline speed). Pump 102C is approaching the middle of the suction stroke as indicated by the arrow. During this suction stroke, pump 102C can operate at a reduced speed (e.g., half the baseline speed).

[0041] Figure 4 It shows that it is in Figure 3 The pumps at the times shown are as follows: Pump 102A begins its suction stroke, moving upwards at a speed less than the baseline speed, as indicated by the arrow. Pump 102B moves downwards at the baseline speed during the discharge stroke, as indicated by the arrow. Pump 102C approaches the end of its suction stroke, as indicated by the arrow. During this suction stroke, pump 102C can operate at a reduced speed (e.g., half the baseline speed).

[0042] Figure 5 It shows that it is in Figure 4 The pumps after the indicated time. Pump 102A partially completes its suction stroke, moving upward at a speed less than the baseline speed, as indicated by the arrow. Pump 102B has completed its discharge stroke and moves upward back during the suction stroke, as indicated by the arrow. During this suction stroke, pump 102B can operate at a reduced speed. Pump 102C begins its discharge stroke, as indicated by the arrow. During this discharge stroke, pump 102C can operate at the baseline speed.

[0043] This cycle can continue, allowing each pump to alternately discharge at a baseline speed and retract at a reduced speed. The net effect is to provide a highly uniform fluid flow rate while minimizing piston speed.

[0044] In the optional configuration, you can use, such as Figure 3 The diagram shows two or more first-stage pumps, independently controlled using a dynamic sequence that is the opposite of a static sequence. For example, if two first-stage pumps are used, one of them can operate at a variable speed. This is useful when one of the first-stage pumps is nearing the end of its discharge cycle but requires additional flow to supply the second-stage pump. In this case, an independent controller can be used to accelerate the discharge stroke of the other first-stage pump, allowing it to "catch up" with the other first-stage pump's cycle and ensuring sufficient flow is supplied to the second-stage pump.

[0045] Another possible use of device 100 is truck unloading. Conventionally, hydrogen is stored in transport containers (in...) Figure 6 The container (illustrated as “200”) is transported to hydrogen filling station 10. The transport container 200 may be, for example, a tank mounted on a truck or railcar.

[0046] Typically, hydrogen is stored as a liquid at 18-25 K and approximately 1.4 bar in transport container 200. In the prior art, a thermally intense process known as pressure build-up is used to generate a pressure differential sufficient to push the liquid hydrogen from transport container 200 to refill station 10. During this process, a large amount of hydrogen is vented to the atmosphere to release the pressure in the transport container after the transfer. If device 100 is to be used for this purpose, analysis has shown that significant savings in hydrogen loss can be achieved because the transport container pressure can be kept low and device 100 will be able to efficiently transfer the liquid hydrogen.

[0047] refer to Figure 6 To achieve this function, transport container 200 will be connected to inlet port 108. First shut-off valve 128 will be closed and second shut-off valve 130 will be opened.

[0048] The first-stage pump 102 is then operated by the first-stage driver 120 in a similar manner to that described above, moving liquid hydrogen from the transport container 200 to the bulk storage tank 18 as a liquid at approximately 18-25 K and approximately 0.27-2.5 bar. The hydrogen flow path is from the transport container 200, through the inlet valve 122, through the pump 102, the first shut-off valve 128, the outlet check valve 132, and finally into the bulk storage tank 18. The second-stage pump 104 will not be used. Alternatively, in a configuration where both the inlet valve 122 and the second shut-off valve 130 are actuated valves, they can be cyclically actuated in sync with the operation of the first-stage pump element 112. For example, during the suction stroke, the inlet valve 122 will be open and the second shut-off valve 130 will be closed, and during the discharge stroke, the inlet valve 122 will be closed and the second shut-off valve 130 will be open. In this configuration, the outlet check valve 132 is eliminated. This configuration can reduce or eliminate pressure losses across the valves during pump operation.

[0049] Figure 6 The pump configuration in the middle can optionally be used to move liquid hydrogen directly from bulk storage tank 18 as a liquid at pressures up to 16 bar to a vehicle (not shown) using hydrogen as fuel. To achieve this transfer, bulk storage tank 18 will be coupled to... Figure 6 The inlet valve 122 in the vehicle (e.g.) Figure 1 Vehicle 12) will be connected to Figure 6 The outlet check valve 132 in the middle.

[0050] This device offers several advantages. The first-stage pump subcools the hydrogen supplied from the liquid tank by pressurizing the liquid to the range of 8 to 10 barg and can operate slowly and on demand, which allows for a more efficient design of a second pump stage for high pressure. A significant advantage will be the ability to facilitate higher operating speeds for the second stage while eliminating over-pumping from the first stage. Another significant advantage is the ability to send the discharge from the first stage to different destinations.

[0051] Compared to existing pumps with interconnected stages, incorporating independent drivers may reduce the system's thermal conductivity; however, the nature of the low-pressure subcooled chamber allows for reduced material stiffness and thus very effective thermal insulation. Notably, the pump rod structure load in the first-stage pump will be significantly smaller compared to the second-stage pump; therefore, its construction can be lighter. Similarly, by eliminating the bidirectional load of the conventional two-stage pump driver, the load of the second-stage pump 104 can be completely converted to a unidirectional load (i.e., compression only or tension only), which allows for structural reconfiguration to improve thermal insulation efficiency.

[0052] The hydrogen pumping and compression apparatus and method have been described above. All features disclosed in this specification (including any appended claims, abstracts and drawings) and / or all steps of any method or process so disclosed may be combined in any combination, except that at least some of these features and / or steps are mutually exclusive combinations.

[0053] Unless otherwise expressly stated, each feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by an alternative feature for the same, equivalent, or similar purpose. Therefore, unless otherwise expressly stated, each disclosed feature is merely one example of a range of generally equivalent or similar features.

[0054] This invention is not limited to the details of the foregoing(one or more) embodiments. The invention extends to any novel one or any novel combination of features disclosed in this specification (including any appended claims, abstract, and drawings), or to any novel one or any novel combination of steps of any method or process so disclosed.

Claims

1. A hydrogen pumping and compression device, comprising: A positive displacement first-stage pump, the first-stage pump comprising pump elements disposed in a pump chamber having an inlet port and an outlet port; The first-stage driver is connected to the first pump element; An inlet valve that is in flow communication with the inlet port of the first-stage pump; A positive displacement second-stage pump, the second-stage pump comprising pump elements disposed in a pump chamber having an inlet port and an outlet port; The second-stage driver is connected to the pump element of the second-stage pump; as well as A delivery pipeline that interconnects the outlet port of the first-stage pump and the inlet port of the second-stage pump.

2. The apparatus according to claim 1, characterized in that: The delivery pipeline is connected to the buffer volume; and The buffer volume includes an exhaust valve that communicates with the atmosphere or a bulk storage space for vapor.

3. The apparatus according to claim 1, characterized in that, The inlet valve is operated by an actuator.

4. The apparatus according to claim 3, characterized in that, The device also includes an electronic controller operatively connected to the first-stage driver, the second-stage driver, and the inlet valve.

5. The apparatus according to claim 1, characterized in that, The device also includes a pressure sensor disposed downstream of the first-stage pump, wherein the pressure sensor is operable to sense hydrogen pressure and generate a signal representing hydrogen pressure, and is operably connected to an electronic controller operably connected to the first-stage driver and the second-stage driver.

6. The apparatus according to claim 1, characterized in that, The sweep volume of the first stage pump is variable relative to the sweep volume of the second stage pump at a ratio from 1:1 to 50:

1.

7. The apparatus according to claim 1, characterized in that: It includes two or more positive displacement first-stage pumps, each positive displacement first-stage pump including a pump element disposed in a pump chamber having an inlet port and an outlet port; as well as The delivery pipeline interconnects the outlet ports of the two or more positive displacement first-stage pumps with the inlet ports of the second-stage pumps.

8. The apparatus according to claim 1, characterized in that, The delivery pipeline is connected to the outlet port of the first-stage pump via a tee and is equipped with a first shut-off valve and a second shut-off valve, wherein the first shut-off valve and the second shut-off valve can be selectively configured to direct the flow from the first-stage pump to the second-stage pump or a storage tank or a vehicle that directly receives liquid hydrogen as fuel.

9. A method for pumping and compressing hydrogen, comprising: The first-stage pump with positive displacement is operated using a first-stage driver to extract hydrogen as a liquid at a temperature of 18-25K and a pressure of 1-6 bar from a bulk fuel storage tank, and to discharge the hydrogen as a liquid at a temperature of 20-30K and a pressure of 2-20 bar. as well as Simultaneously, a positive displacement second-stage pump is operated using a second-stage driver independent of the first-stage driver to obtain liquid hydrogen from the first-stage pump, compress the liquid hydrogen into a gas at a temperature of 45-70K and a pressure of at least 350 bar, and discharge the gas into a ready storage tank.

10. The method according to claim 9, characterized in that, The sweep volume of the first stage pump varies relative to the sweep volume of the second stage pump during operation at a ratio ranging from 1:1 to 50:

1.

11. The method according to claim 9, characterized in that: The liquid hydrogen is delivered from the first-stage pump to the second-stage pump through a delivery line with a buffer volume.

12. The method according to claim 11, characterized in that, The method further includes: Monitor the pressure of the liquid hydrogen in the buffer volume; and In response to the pressure exceeding a predetermined value, some of the liquid hydrogen is discharged into the atmosphere or a bulk storage vapor space via an exhaust valve in order to reduce the pressure.

13. The method according to claim 9, characterized in that, The method also includes using an electronic controller to control the first-stage driver and the second-stage driver.

14. The method according to claim 13, characterized in that, The method further includes: Hydrogen pressure is sensed using a pressure sensor located downstream of the first-stage pump; and The first actuator is operated as needed using the feedback signal from the pressure sensor to maintain the target pressure.

15. The method according to claim 9, characterized in that, Two or more of the positive displacement first-stage pumps are operated, each of the positive displacement first-stage pumps having its own first-stage driver, to extract hydrogen as a liquid at a temperature of 18-25K and a pressure of 1-6 bar from the bulk fuel storage tank, and to discharge the hydrogen as a liquid at a temperature of 20-30K and a pressure of 2-20 bar.

16. The method according to claim 16, characterized in that, Each of the first-stage pumps discharges at a baseline speed and retracts at a reduced speed.

17. The method according to claim 9, characterized in that, The hydrogen is allowed to pass through an actuator-operated inlet valve to the first-stage pump.

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