Cryogenic fluid distribution system and method

Abstract

In a system for dispensing a cryogenic fluid, a bulk tank is configured to contain a supply of cryogenic liquid. The reservoir is configured to receive cryogenic liquid from the bulk tank. A first positive displacement pump is positioned within the reservoir and configured to be submerged within the cryogenic liquid stored within the reservoir and to pump the cryogenic liquid stored within the reservoir. A second positive displacement pump is positioned within the sump and is configured to be submerged within the cryogenic liquid stored within the sump and to pump the cryogenic liquid stored within the sump. The evaporation heat exchanger is configured to receive and evaporate the cryogenic liquid pumped from the first pump and / or the second pump.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 345,193, filed May 24, 2022, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention generally relates to systems and methods for dispensing cryogenic fluids and, more particularly, to cryogenic fluid dispensing systems and methods including at least two pumps located within a sump that selectively receives cryogenic liquid for pumping from a bulk storage tank. Background Art

[0004] Liquid hydrogen refueling stations are an emerging technology that is gaining more and more attention due to the advancement of the development and use of hydrogen-fueled fuel cell electric vehicles. The SAE J2601 refueling protocol defines the delivery of gaseous hydrogen to compressed hydrogen storage tanks within the vehicle. Typically, such compressed hydrogen storage tanks within the vehicle supply gaseous hydrogen to the fuel cell to power the vehicle.

[0005] Fueling stations that include liquid hydrogen storage offer advantages over compressor / tube trailer type stations, where the tubes contain the hydrogen. More specifically, liquid hydrogen storage at a fueling station provides the opportunity to mix cold hydrogen with hot hydrogen to achieve a target dispenser temperature of -38°C. In addition, the storage capacity of a liquid hydrogen storage station is much greater than the actual storage capacity of a compressor / tube trailer type station. Tube trailers are typically 4000 psig, so they require an on-site compressor to raise the pressure within the buffer tank to 12000 psig (830 barg). In addition, the small capacity of a tube trailer typically requires that the tube trailer be replaced (full for empty) multiple times per day.

[0006] A compressor may also be used in conjunction with liquid hydrogen storage, where the compressor extracts gaseous hydrogen from the top of the liquid hydrogen tank, heats the hydrogen, compresses it and directs the resulting gas into a high-pressure buffer tank (e.g., a tank rated at approximately 15,000 psig). The compressor in such a system typically does not have the ability to directly refuel the vehicle. To address this issue, a combination of the compressor and buffer tank flow is sent to the vehicle being refueled to achieve the J2601 specified flow rate. The J2601 specified temperature can be achieved by directing the hydrogen gas stream (with the J2601 specified flow rate) through a heat exchanger that also receives a liquid hydrogen stream from a bulk storage tank, thereby cooling the hydrogen gas stream. The heated liquid hydrogen stream returns to the bulk storage tank. This sends heat to the bulk storage tank, but is able to cool the hydrogen gas stream to -40°F. The compressor extracts gas from the tank headspace, reducing the bulk storage tank pressure in order to handle the heating in the system. However, this approach is limited by the high equipment cost of the required compressor. Alternatively, a commercial refrigeration system can be used to cool the hydrogen gas stream (having a J2601 specified flow rate) to the J2601 specified temperature, but this also increases equipment cost.

[0007] The cost of the compressor is much higher than the cost of the pump. This is especially true if the mass flow rate of the compressor matches the mass flow rate of the pump. Therefore, a positive displacement (piston) pump from a liquid hydrogen tank represents an economical answer to hydrogen refueling for fuel cell electric vehicles. The pumped liquid hydrogen is evaporated to a target temperature through an evaporator and mixing and control valves. A hydrogen buffer tank can store the evaporated liquid hydrogen and be used to supplement the flow from the pump during distribution to balance the load of the pump operation to some extent, depending on the instantaneous refrigeration required to achieve the delivery temperature. This allows a slightly smaller pump to be used. The disadvantages of this approach include the additional equipment cost of the hydrogen buffer tank and the additional pumping time to refill the buffer tank. Summary of the invention

[0008] Aspects of the present subject matter may be implemented individually or together in the devices and systems described and claimed below. These aspects may be used alone or in combination with other aspects of the subject matter described herein, and the description of these aspects together is not intended to exclude the individual use of these aspects or the individual claims of these aspects or the different combinations set forth in the appended claims.

[0009] In one aspect, a system for dispensing cryogenic fluids includes a bulk tank configured to hold a supply of cryogenic liquid. A storage tank is configured to receive cryogenic liquid from the bulk tank. A first positive displacement pump is positioned within the storage tank and is configured to be immersed in the storage tank and pump the cryogenic liquid stored in the storage tank. A second positive displacement pump is also positioned within the storage tank and is configured to be immersed in the storage tank and pump the cryogenic liquid stored in the storage tank. An evaporative heat exchanger is configured to receive and evaporate the cryogenic liquid pumped from the first pump and / or the second pump.

[0010] In another aspect, a method for distributing a cryogenic fluid includes the steps of storing a cryogenic liquid in a bulk tank, directing the cryogenic liquid from the bulk tank to a storage tank, immersing a first positive displacement pump and a second positive displacement pump in the cryogenic liquid in the storage tank, pumping the cryogenic liquid from the storage tank to an evaporative heat exchanger using the first positive displacement pump and / or the second positive displacement pump, evaporating the cryogenic liquid in the evaporative heat exchanger to form a cryogenic vapor, and distributing the cryogenic vapor. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of a jacketed bulk storage tank and a sump containing a pump in an embodiment of a cryogenic fluid distribution system of the present disclosure.

[0012] Figure 2 is a schematic diagram of an evaporation subsystem in an embodiment of a cryogenic fluid distribution system of the present disclosure.

[0013] Figure 3 is a schematic diagram of a heating fluid subsystem in an embodiment of a cryogenic fluid distribution system of the present disclosure. DETAILED DESCRIPTION

[0014] While embodiments of the present disclosure are presented below as a hydrogen refueling station for fuel cell vehicles, it should be understood that the technology may be used to dispense alternative cryogenic fluids in alternative applications.

[0015] It should be noted herein that lines, conduits, ducts, channels and similar structures and corresponding flows are sometimes indicated by the same element numerals as shown in the figures.

[0016] Reference numerals introduced in the specification in conjunction with the drawings may be repeated in one or more subsequent drawings for shared elements or features without additional description in the specification, in order to provide context for the other features.

[0017] In the claims, letters are used to identify claimed steps (e.g., a, b, and c). These letters are used to aid in referring to method steps and are not intended to indicate the order in which the claimed steps should be performed, unless and only to the extent such an order is specifically recited in the claims.

[0018] In an embodiment of the cryogenic fluid distribution system of the present disclosure, the bulk tank 10 and a pair of storage tanks 12a, 12b are positioned within a jacket 14. Air is at least partially exhausted from the interior of the jacket to provide vacuum insulation for the bulk tank 10 and the storage tanks 12a, 12b. The jacket 14 may be buried underground to preserve space above ground and provide insulation for the jacket.

[0019] The bulk tank 10 contains a supply of liquid hydrogen 16 and is refilled by a filling line system, which is generally indicated at 18 and includes a portion that passes through the interior of the jacket 14. Depending on the arrangement of valves 25, 27, the tank can be filled from the liquid side via the filling line 22 or via the filling line 23 and a spray bar 24 located in the head space of the tank. Liquid entering the bulk tank 14 via the spray bar 24 can collapse the pressure head to reduce the pressure in the tank. In addition, the bulk tank 10 is provided with a vent line 26, which leads to a vent standpipe via a fitting 27. The bulk tank 14 is also provided with emergency vent lines 28, 32, which are provided with emergency vent valves 34, 36, respectively.

[0020] When valves 42a, 42b are opened, respectively, liquid hydrogen 16 from bulk tank 10 is transferred to storage tanks 12a, 12b through lines 38a, 38b.

[0021] A level sensor (not shown) is configured to determine the level of liquid hydrogen in each tank 12a, 12b to provide an indication when the tank needs to be refilled. By way of example only, the level sensor may include commonly owned U.S. Patent Nos. 6,542,848; 6,782,339 and / or 6,944,570 to Neeser et al., the contents of each of which are incorporated herein by reference.

[0022] The first positive displacement pump 44 and the second positive displacement pump 46 are each located in the storage tank 12a and are immersed in liquid hydrogen 48 supplied by the bulk tank 10, as will be described below. The inlet of the pump receives liquid in the storage tank for pumping. By being immersed in liquid hydrogen 48, the pumps 44 and 46 remain cooled between uses. Therefore, the need to recirculate liquid through the pumps for cooling at startup is minimized or eliminated.

[0023] Motors 52 and 54 located outside the storage tank 12a drive pumps 44, 48, respectively, via drive rods or shafts. As described in commonly assigned U.S. Patent Application Publication No. US2021 / 0404604 to Drube et al., the contents of which are incorporated herein by reference, subcooling of the liquid hydrogen 48 in the storage tank 12a can be achieved by heating the vapor in the head space of the storage tank via heat transfer from the motor 52 to the head space via the corresponding drive rods or shafts. The motors 52, 54 are preferably hydraulic motors.

[0024] like Figure 1 As shown, tank 12b similarly includes two pumps 56, 58, which are driven by motors 62, 64. The structure and operation of tank 12b and pumps 56, 58 are the same as tank 12a and pumps 44, 46. Therefore, the following discussion will focus only on tank 12a and pumps 44, 46 to avoid repetition, and also applies to tank 12b and pumps 56, 58.

[0025] Although two reservoirs are shown, each including two pumps, the number of reservoirs may vary, and the number of pumps per reservoir may be greater than two.

[0026] Liquid line 66 receives liquid hydrogen from the outlet of pump 44 and directs it to the evaporation subsystem, as described below with reference to Figure 3 Liquid line 68 similarly receives liquid hydrogen from the outlet of pump 46 and directs it to the evaporation subsystem.

[0027] Motor 52 receives hydraulic fluid from a pressurized source via line 72, as is known in the art, thereby actuating pump 44. The heated hydraulic fluid exits motor 52 via line 74. Motor 54 similarly receives hydraulic fluid from a pressurized source via line 76, thereby actuating pump 46. The heated hydraulic fluid exits motor 54 via line 78.

[0028] When sump 12a is drained for maintenance or repair of the pump, an inert purge fluid, such as nitrogen vapor, is directed through pumps 44, 46 and sump 12a via purge fluid supply line 82 and purge fluid recovery line 84. By way of example only, the nitrogen vapor may be provided from a tank containing a pressurized supply of nitrogen vapor or a tank containing liquid nitrogen, which is directed to a heat exchanger or other heating device prior to line 82.

[0029] Reference Figure 2 , through line 66 (from Figure 1 Pump 44) and / or 68 (from Figure 1 Pumped hydrogen delivered by pump 46) is received by line 87 of the evaporation subsystem, generally indicated at 86. The hydrogen liquid flowing through line 87 can be directed through line 88 to evaporation heat exchanger 92, where it is heated and evaporated by a heating fluid stream that enters the heat exchanger through line 94 and exits the heat exchanger through line 96. The resulting hydrogen vapor stream exits evaporation heat exchanger 92 through line 98. Thus, Figure 2 The evaporative heat exchanger 92 evaporates heat from Figure 1 The hydrogen liquid is pumped to pumps 44, 46. The hydrogen vapor stream flows through line 106 and exits the evaporation subsystem through line 108 to a dispenser for delivery to a fueled vehicle.

[0030] By opening valve 104, a portion of the hydrogen vapor flow in line 98 can be directed to buffer tank 102 to provide pressurized hydrogen vapor storage in tank 102. When the pressure of the hydrogen vapor stored in tank 102 reaches a desired level, valve 104 is closed. If necessary, pressurized hydrogen vapor from tank 102 can be used to supplement the hydrogen flow through line 88 by opening valve 105 (valve 104 remains closed). For example, valve 105 can be opened when pumps 44, 46 cannot keep up with the demands of the distribution system.

[0031] When the heating bypass valve 114 is opened or partially opened, a portion of the hydrogen liquid flowing through the pipeline 87 can be directed through the heating bypass line 112. The bypass line 112 is connected to the pipeline 106 so that the hydrogen liquid flowing in the bypass line merges with the hydrogen vapor flowing through the pipeline 106. As a result, the temperature of the hydrogen vapor distributed through the pipeline 108 can be adjusted by operating the valve 114.

[0032] As above reference Figure 2 As shown, liquid hydrogen flowing through heat exchanger 92 is heated by a flow of heating fluid that enters the heat exchanger through line 94 and leaves the heat exchanger through line 96 . Figure 3 A subsystem is shown for providing a heating fluid stream 94 to a heat exchanger 92. A heating fluid storage or supply tank 122, preferably jacketed to provide vacuum insulation, contains a heating fluid supply 124, which may contain or include, by way of example only, propylene glycol or other hydrocarbons. The heating fluid storage tank may be provided with a pressure building circuit including a heat exchanger 126, which vaporizes liquid from the bottom of the tank and directs the resulting vapor to the tank headspace.

[0033] Liquid from the heating fluid storage tank may be pumped by pump 128 as stream 94 to heat exchanger 92. As a result, the liquid hydrogen flowing through heat exchanger 92 is vaporized and is discharged as vapor stream 98 (eg, Figure 2 The resulting cooled heated fluid stream 96 exits the heat exchanger 92 and, depending on the settings of valves 132, 134 and 136, may be directed to the hydraulic fluid heat exchanger 142 and / or the auxiliary heat exchanger 144 for heating and / or directed back to the bulk tank 122.

[0034] After the hydraulic fluid has been heated by the articulation of the corresponding pump, Figure 3 The hydraulic fluid heat exchanger 142 is connected via Figure 1 The pipelines 74 and / or 78 receive the Figure 1 The hydraulic fluid of the pump motor 52 and / or 54. Figure 3 When valve 136 is at least partially open, the cooled heated fluid stream 144 entering heat exchanger 142 is replaced by the cooled heated fluid stream 144 from lines 74 and / or 78 ( Figure 1 ) of the hydraulic fluid to provide a heated heating fluid flow 146.

[0035] if Figure 3 If both valves 134 and 136 are at least partially open, a portion of stream 96 flows through lines 152 and 154 and another portion flows to heat exchanger 142. As a result, streams 146 and 154 combine to form stream 148, which flows into auxiliary heat exchanger 144. Alternatively, if valve 134 is closed, all of stream 146 flows into auxiliary heat exchanger 144 as stream 148.

[0036] Auxiliary heat exchanger 144 provides heating of stream 148 and, by way of example only, may be a catalytic heat exchanger, a forced air heat exchanger, an electric heat exchanger, or an ambient heat exchanger. Figure 3 One auxiliary heat exchanger 144 is shown, but two or more auxiliary heat exchangers may be used, or the auxiliary heat exchanger 144 may be eliminated. The further heated heating fluid stream 156 leaves the auxiliary heat exchanger 144 and is directed back to the spray bar 158 located in the heating fluid storage tank 122, so that the heating fluid 124 in the tank is heated.

[0037] If bypass valve 132 is at least partially open, flow 162 will merge with flow 156 before the resulting flow 164 is directed back to nozzle 158 within heating fluid storage tank 122. As a result, the temperature of the heating fluid returning to storage tank 122 can be controlled.

[0038] By providing two (or more) pumps in the storage tank, the above embodiments provide a wider range of pumping rates. More specifically, a single pump within the storage tank may be operated, or both pumps may be operated. In addition, the pumping rates and / or hydraulic coordination of the two pumps may be adjusted, up to and including idling one of the pumps. In addition, the use of two pumps enables faster supercooling of the liquid hydrogen in the storage tank, as the storage tank receives heat from both pump motors when both pumps are operating.

[0039] Furthermore, the above described embodiment provides efficiency because it uses thermal energy from the heated hydraulic fluid returning from the pump motor to recondition the heated fluid after it is used to vaporize the pumped hydrogen liquid.

[0040] While the preferred embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications can be made thereto without departing from the spirit of the invention.

Claims

1. A system for dispensing a cryogenic fluid, comprising: a. A bulk tank configured to contain a cryogenic liquid supply; b. a storage tank configured to receive cryogenic liquid from a bulk tank; c. a first positive displacement pump positioned within the storage tank and configured to be immersed in and pump the cryogenic liquid stored in the storage tank; d. a second positive displacement pump positioned within the storage tank and configured to be immersed in and pump the cryogenic liquid stored in the storage tank; e. An evaporation heat exchanger configured to receive and evaporate the cryogenic liquid pumped from the first pump and / or the second pump.

2. The system according to claim 1, wherein: The bulk tank and the sump are located within a jacket, wherein the interior of the jacket is at least partially evacuated of air.

3. The system according to claim 1, wherein: The cryogenic liquid is liquid hydrogen.

4. The system according to claim 1, wherein: The evaporative heat exchanger receives a heating fluid such that the cryogenic liquid is heated and evaporated by the heating fluid in the evaporative heat exchanger.

5. The system according to claim 4, wherein: The first positive displacement pump and the second positive displacement pump are jointly or independently powered by at least one hydraulic motor and also include a hydraulic fluid heat exchanger configured to receive cooled heating fluid from the evaporative heat exchanger, wherein the hydraulic fluid heat exchanger is also configured to receive heated hydraulic fluid from at least one hydraulic motor so that the cooled heating fluid from the evaporative heat exchanger is heated in the hydraulic fluid heat exchanger.

6. The system of claim 5, further comprising a heating fluid reservoir in fluid communication with the hydraulic fluid heat exchanger for receiving and storing heating fluid, the heating fluid reservoir being configured to provide heating fluid to the evaporative heat exchanger.

7. The system of claim 6, further comprising an auxiliary heat exchanger configured to receive and heat the heating fluid from the hydraulic fluid heat exchanger and direct the heating fluid to a heating fluid supply tank.

8. A method for dispensing a cryogenic fluid, comprising the steps of: a.Store cryogenic liquids in bulk tanks; b. Direct cryogenic liquid from bulk tanks to storage tanks; c. immersing the first positive displacement pump and the second positive displacement pump in the cryogenic liquid in the storage tank; d. using a first positive displacement pump and / or a second positive displacement pump to pump the cryogenic liquid from the storage tank to the evaporative heat exchanger; e. evaporating the cryogenic liquid in an evaporative heat exchanger to form cryogenic vapor; f. Distribute low temperature steam.

9. The method according to claim 8, wherein: The cryogenic liquid is liquid hydrogen.

10. The method according to claim 8, wherein: Step e is performed using a heating fluid which heats and evaporates the cryogenic liquid in the evaporative heat exchanger, thereby cooling the heating fluid.

11. The method according to claim 10, wherein: During step d, the first positive displacement pump is driven by a first hydraulic motor and the second positive displacement pump is driven by a second hydraulic motor, and further comprising the step of heating the cooled heating fluid in a hydraulic fluid heat exchanger using hot hydraulic fluid from the first hydraulic motor and / or the second hydraulic motor.

12. The method according to claim 11, further comprising the steps of: Heating fluid is received from the hydraulic fluid heat exchanger and stored in a heating fluid storage tank.

13. The method according to claim 12, further comprising the steps of: An auxiliary heat exchanger is used to heat the heating fluid.

14. The method according to claim 8, further comprising the steps of: The bulk tank and the sump are isolated using a jacket containing the bulk tank and the sump, wherein the interior of the jacket is at least partially evacuated of air.

Images