Hydrogen-cooled turboexpander

Abstract

The hydrogen dispensing system includes a hydrogen storage tank for storing hydrogen gas, a turboexpander generator fluidly connected to the hydrogen storage tank, and a dispenser fluidly connected to the turboexpander generator, wherein the turboexpander generator receives a flow of hydrogen gas from the hydrogen storage tank at an inlet of the turboexpander generator, reduces the pressure and temperature of the hydrogen gas flow, and outputs the hydrogen gas to the dispenser.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 17 / 935,740, filed September 27, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to power generation systems. [Background technology]

[0003] Hydrogen is a rapidly expanding global energy storage market. Hydrogen is used in many manufacturing processes, from oil refining to food processing. Hydrogen is also used as a fuel source for gas turbines and in a wide range of fuel cells for power generation in the industrial and civil transportation sectors. When hydrogen is transferred between containers, the Joule-Thomson effect can cause its temperature to increase and its energy density to decrease. Summary of the Invention

[0004] This disclosure describes cooling hydrogen gas in a dispensing operation.

[0005] In some aspects, the method includes receiving a flow of hydrogen gas from a hydrogen storage tank at an inlet of a turboexpander generator, reducing the pressure and temperature of the hydrogen gas in the turboexpander generator, and outputting the hydrogen gas from the turboexpander generator toward a hydrogen dispenser.

[0006] This and other aspects may include one or more of the following features. Reducing the pressure and temperature of the hydrogen gas with the turboexpander generator may include directing the flow of hydrogen gas to a turbine wheel of the turboexpander generator, driving rotation of the turbine wheel with the flow of hydrogen gas, and generating an electric current by a generator of the turboexpander generator in response to the turbine wheel rotating. The method may further include supplying the generated electric current from the turboexpander generator to an electric chiller fluidly connected to the turboexpander generator, the electric chiller configured to cool the flow of hydrogen gas. The method may further include directing the generated electric current from the turboexpander generator to power electronics. The power electronics may include a variable speed drive connected to the turboexpander generator, and directing the generated electric current to the power electronics may include converting the generated electric current, by the variable speed drive, to alternating current compatible with a power grid. Outputting the hydrogen gas from the turboexpander generator to a hydrogen dispenser may include outputting the hydrogen gas at a desired output temperature. The method may further include cooling the flow of hydrogen gas from the hydrogen storage tank to the inlet of the turboexpander generator using an electric chiller fluidly connected to the turboexpander generator. Cooling the flow of hydrogen gas with the electric chiller may include controlling the electric chiller with a controller of a process control system. The method may further include measuring a temperature of the flow of hydrogen gas from the outlet of the turboexpander generator with a temperature sensor in the process control system, and controlling the electric chiller with the controller of the process control system may include controlling the electric chiller based on the measured temperature of the flow of hydrogen gas from the outlet of the turboexpander generator.The method may further include measuring the pressure of the hydrogen gas flow to the inlet of the turboexpander generator or the hydrogen gas flow from the outlet of the turboexpander generator with a pressure sensor in the process control system, and measuring the temperature of the hydrogen gas flow upstream of the electric chiller with a temperature sensor in the process control system, and controlling the electric chiller with the controller of the process control system may include controlling the electric chiller based on the measured pressure from the pressure sensor and the measured temperature from the temperature sensor.

[0007] In a particular case, a hydrogen dispensing system includes a hydrogen storage tank for storing hydrogen gas, a turboexpander generator fluidly connected to the hydrogen storage tank, and a dispenser fluidly connected to an outlet of the turboexpander generator, the turboexpander generator receiving a flow of hydrogen gas from the hydrogen storage tank at an inlet of the turboexpander generator, the turboexpander generator reducing the pressure and temperature of the hydrogen gas flow, and the dispenser receiving the flow of hydrogen gas from the outlet of the turboexpander generator.

[0008] This and other aspects may include one or more of the following features. The turboexpander generator may include a turbine wheel that receives the hydrogen gas flow and rotates in response to expansion of the hydrogen gas flowing through its inlet and outlet, a rotor connected to the turbine wheel and rotating with the turbine wheel, and a stationary stator that causes the turboexpander generator to generate alternating current through rotation of the rotor within the stator. The hydrogen dispensing system may further include a power electronics system electrically connected to an electrical output of the turboexpander generator, the power electronics system receiving the alternating current from the turboexpander generator. The power electronics system may include a variable speed drive connected to the electrical output of the turboexpander generator, the variable speed drive converting the alternating current received from the turboexpander generator to alternating current compatible with a power grid. The hydrogen dispensing system may further include an electric chiller fluidly connected to the turboexpander generator between the hydrogen storage tank and the turboexpander generator, the electric chiller cooling the hydrogen gas flow. The electric chiller may be electrically connected to the turboexpander generator, and the turboexpander generator supplies generated alternating current to the electric chiller. The hydrogen dispensing system may further include a process control system communicatively connected to the electric chiller and including a controller controlling the electric chiller. The process control system may further include a temperature sensor on an outlet side of the turboexpander generator, the temperature sensor measuring a temperature of the hydrogen gas flow from the outlet of the turboexpander generator, and the process control system controlling the electric chiller based on the measured temperature from the temperature sensor.The process control system may further include a pressure sensor measuring a pressure of the hydrogen flow to the inlet of the turboexpander generator or the hydrogen flow from the outlet of the turboexpander generator, and a temperature sensor measuring a temperature of the hydrogen flow upstream of the electric chiller, wherein the process control system controls the electric chiller based on the measured pressure from the pressure sensor and the measured temperature from the temperature sensor.

[0009] Certain aspects of the present disclosure include a method including cooling a flow of hydrogen gas from a hydrogen storage tank with an electric chiller, receiving the cooled flow of hydrogen gas from the electric chiller at an inlet of a turboexpander generator, reducing the temperature of the cooled hydrogen gas with the turboexpander generator, and outputting the hydrogen gas from the turboexpander generator to a hydrogen dispenser.

[0010] The details of one or more embodiments of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, drawings, and claims. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of an exemplary hydrogen dispensing system. [Figure 2] FIG. 2 is a schematic diagram of an exemplary turboexpander generator connected to electrical components that may be used in the exemplary hydrogen dispensing system of FIG. [Figure 3] FIG. 3 is a flow diagram illustrating an exemplary method for cooling hydrogen gas in a hydrogen dispensing system. DETAILED DESCRIPTION OF THE INVENTION

[0012] Like reference symbols in different drawings indicate like elements. The drawings are not to scale.

[0013] The present disclosure describes a system for cooling hydrogen gas during a dispensing operation, such as filling a hydrogen mobility vehicle. The hydrogen dispensing system includes a storage tank for storing hydrogen, a dispenser for dispensing hydrogen, such as to a hydrogen mobility vehicle, and a cooling system for cooling the hydrogen to a desired temperature before dispensing. The cooling system includes a turboexpander generator fluidly connected between the storage tank and the dispenser, which reduces the pressure and temperature of the hydrogen before dispensing it at the dispenser. The operation of reducing the pressure and temperature of the hydrogen gas by the turboexpander generator also generates electricity, which can be used to power other components of the hydrogen dispensing system, supplied to another electrical component, supplied to a power grid, or directed elsewhere. For example, the turboexpander generator extracts enthalpy from the hydrogen before dispensing, thereby reducing the temperature and pressure of the hydrogen gas. In some cases, the cooling system also includes an electric chiller between the storage tank and the dispenser for cooling (i.e., removing heat from) the hydrogen gas. The electric chiller can supplement the turboexpander generator in cooling the hydrogen gas to the desired output temperature. In some cases, the turboexpander generator generates electricity to power the electric chiller, reducing the electric chiller's electrical load. In certain cases, the use of the turboexpander generator completely eliminates the need for the electric chiller; that is, the turboexpander generator reduces the temperature of the hydrogen to the desired output temperature without the assistance of the electric chiller.

[0014] The hydrogen dispensing system includes a process control system that controls the turboexpander generator, the electric chiller, or both, and supplies hydrogen gas to the dispenser at a desired output temperature and / or pressure. For example, the process control system can adjust the amount of pre-cooling performed by the turboexpander, the electric chiller, or both, based on the flow characteristics of the hydrogen passing through the dispensing system. For example, the process control system can include temperature and pressure sensors positioned along the hydrogen flow path between the storage tank and the dispenser to measure the characteristics of the hydrogen flow, and the process control system can control the electric chiller, the turboexpander generator, or both, to provide the desired output temperature at the dispenser.

[0015] Natural gas, hydrogen, and other process gases are pressurized to facilitate efficient transportation through pipelines or storage in storage vessels. The transfer of these gases, such as between a pressure vessel source and a secondary vessel or chamber, is facilitated by a pressure difference between the former, which maintains a higher pressure, and the latter, which maintains a lower pressure. Most process gases have a positive Joule-Thomson coefficient, resulting in a decrease in temperature and an increase in energy density when these gases undergo reduced pressure. However, a limited number of process gases, including hydrogen, may have a negative Joule-Thomson coefficient, resulting in an increase in temperature and a decrease in energy density when these gases undergo reduced pressure. For example, under conventional conditions, filling a hydrogen pressure vessel increases the gas temperature, resulting in a decrease in energy density. To increase the energy density of hydrogen gas within a receiving volume, it is more efficient to fill a given receiving volume with more hydrogen. For example, hydrogen mobility vehicles (e.g., hydrogen fuel cell vehicles, mining tractors, or other vehicles receiving hydrogen gas) can travel longer distances with increased hydrogen storage capacity. Existing industry standards, such as SAE J2601 (Society of Automotive Engineers), specify a minimum temperature that must be achieved before hydrogen can be dispensed into a vehicle, and an electric chiller is utilized to remove heat from the hydrogen. In the present disclosure, a turboexpander generator is positioned between the storage tank and the dispenser to reduce the temperature of the hydrogen gas flow and generate electricity. The turboexpander generator reduces the temperature of the hydrogen gas by extracting enthalpy from the hydrogen prior to the filling operation. For example, the turboexpander generator enables near-isentropic gas expansion, which reduces the temperature of the hydrogen gas, rather than isenthalpic gas expansion, which increases the temperature of the hydrogen gas. The electricity generated from the turboexpander generator can be used to power the electric chiller or to power other components within or outside the hydrogen dispensing system.

[0016] FIG. 1 is a schematic diagram of an exemplary hydrogen dispensing system 100 that can be used in hydrogen fueling applications, such as for hydrogen mobility vehicles. The hydrogen dispensing system 100 of FIG. 1 includes a hydrogen storage container 102, a hydrogen storage tank 104, a compressor 106 between the storage container 102 and the storage tank 104, a cooling system 108 including an electric chiller 110 and a turboexpander generator 112, and a dispenser 114. The hydrogen dispensing system 100 operates to store, cool, and deliver hydrogen gas or other gaseous fuel to a vehicle 115. The exemplary hydrogen dispensing system 100 of FIG. 1 illustrates the vehicle 115 as a hydrogen mobility vehicle, which may include a hydrogen fuel cell vehicle, a mining tractor, or other vehicle that receives hydrogen gas. However, the vehicle 115 may take other forms that can travel to and from the dispenser 114. In some examples, a vehicle 115 (or other equipment) arrives at a dispenser 114, receives cooled hydrogen gas from the dispenser 114, and leaves the dispenser 114. The dispenser 114 can be located at a filling station through which a number of vehicles to be filled circulate, and the dispenser 114 can supply hydrogen gas to one or more vehicles at the filling station. In some cases, the dispenser 114 is a point of sale.

[0017] The storage vessel 102 may include a mobile storage vehicle, such as a tube trailer truck, for transporting hydrogen in one or more storage tanks of the tube trailer truck to a stationary storage tank 104. The compressor 106 is used to compress the hydrogen as it is transferred from the storage vessel 102 to the storage tank 104 and is disposed along the flow path of the hydrogen gas between the storage vessel 102 and the storage tank 104. The compressor 106 may be separate from the storage vessel 102 and the storage tank 104 or may be integral with the storage vessel 102 or the storage tank 104.

[0018] The storage tank 104 stores hydrogen gas until prompted to dispense all or a portion of the stored hydrogen along a flow path through the cooling system 108 and to the dispenser 114 via the control valve 116. The storage tank 104 stores hydrogen gas at a high pressure, such as up to 7,250 pounds per square inch gauge (psig) (i.e., 500 bar-g), and a high temperature, such as up to 80 degrees Fahrenheit (F). The control valve 116 controls the flow of hydrogen gas from the storage tank 104 through a fluid path 118 extending from the storage tank 104 to the dispenser 114. The fluid path 118 may include additional valves and / or pressure regulators other than the control valve 116 to control the flow of hydrogen gas from the storage tank 104. The control valve 116 may be a pressure reducing valve that relieves pressure from the hydrogen gas and reduces the pressure of the hydrogen gas to a more controllable pressure level acceptable to the cooling system 108 and / or the dispenser 114. Although only one control valve 116 is shown in the exemplary hydrogen dispensing system 100 of FIG. 1, the fluid path 118 may include multiple valves in parallel or series, or both, to reduce the pressure of the hydrogen gas to a desired pressure level.

[0019] The cooling system 108 is disposed along a fluid path 118 between the storage tank 104 and the dispenser 114 and serves to cool the hydrogen gas from the storage tank 104. For example, the cooling system 108 reduces the temperature of the hydrogen gas from a first temperature received from the storage tank 104 to a second, lower temperature supplied to the dispenser 114. The turboexpander generator 112, the electric chiller 110, or both reduce the temperature and pressure of the hydrogen gas. For example, the storage tank 104 may store hydrogen gas at approximately 2,500 psig and 80°F, and the dispenser 114 may dispense hydrogen at approximately 500 psig. The dispenser 114 dispenses the cooled hydrogen gas, for example, to a hydrogen mobility vehicle 115, filling a receiving vessel of the vehicle 115 until the pressure within the receiving vessel is approximately 2,500 psig. Electric chiller 110 may be electrically powered to remove heat from the flow of hydrogen passing through chiller 110 on its way to dispenser 114. Cooling system 108 may be capable of cooling hydrogen gas to temperatures as low as -123°F, such as when the pressure is 500 psig. In some examples, when a receiving vessel of vehicle 115 is filled with hydrogen gas output by dispenser 114 at approximately 500 psig and -123°F, the pressure within the receiving vessel increases, for example, to 2,000 psig, and the temperature of the hydrogen gas increases to between 25°F and 75°F. Cooling system 108 reduces the temperature of the hydrogen entering dispenser 114 to offset the expected temperature increase of the hydrogen as it is filled into the receiving vessel of vehicle 115.

[0020] 1 includes an electric chiller 110 in series with a turboexpander generator 112 along a fluid path 118 through which hydrogen gas flows between the storage tank 104 and the dispenser 114. The turboexpander generator 112 is shown downstream of the electric chiller 110, with the hydrogen gas flowing through the electric chiller 110 and then through the turboexpander generator 112. In some cases, the turboexpander generator 112 is positioned upstream of the electric chiller 110, with the output of the turboexpander generator 112 flowing to the electric chiller 110. In other examples, the turboexpander generator 112 is positioned in parallel with the electric chiller 110, for example, to split the flow of hydrogen gas so that a first portion of the hydrogen gas is cooled by the turboexpander generator 112 and a second portion of the hydrogen gas is cooled by the electric chiller 110. In certain cases, the turboexpander generator 112 provides sufficient cooling for the hydrogen gas, in which case the electric chiller 110 is eliminated from the cooling system 108 .

[0021] The turboexpander generator 112 is in fluid communication with the electric chiller 110, the storage tank 104, and the dispenser 114 via a fluid path 118. The turboexpander generator 112 receives a flow of hydrogen gas from the storage tank 104, either directly from the storage tank 104 or via the electric chiller 110, and reduces the temperature and pressure of the hydrogen gas flowing through the turboexpander generator 112. For example, the turboexpander generator 112 reduces the pressure and temperature of the hydrogen gas through a pressure-reducing turbine system, which will be described in more detail below. The turboexpander generator 112 includes an integrally connected turbine section and a generator section, such that the flow of hydrogen gas through the turbine section reduces the pressure of the hydrogen gas while operating the generator section to generate an electric current (e.g., a certain amount of power) that can be supplied to other portions of the exemplary hydrogen dispensing system 100, such as the electric chiller 110, the dispenser 114, a battery, and / or other electrical components or a grid (e.g., a power grid, a local grid, a microgrid, or a municipal grid). The turboexpander generator 112 does not require additional power to reduce the pressure, temperature, or both the pressure and temperature of the hydrogen gas, other than a small amount of power (e.g., 1 kW) to operate a magnetic bearing system (e.g., one or more magnetic bearings described below) within the turboexpander generator 112. Instead, the turboexpander generator 112 is passive; it relies on the flow of hydrogen gas entering the turboexpander generator 112 to extract enthalpy from the hydrogen, reducing the temperature and pressure of the hydrogen gas. The minimum amount of power consumed by the turboexpander generator 112 during operation is less than the more substantial amount of power generated by the turboexpander generator 112. In other words, the amount of power required to operate the parasitic loads (e.g., magnetic bearings) of the turboexpander generator 112 is substantially less than the power output from the operation of the turboexpander generator 112, so the net power output of the turboexpander generator 112 is positive during operation.

[0022] The turboexpander generator 112 outputs the depressurized hydrogen gas at a second, lower temperature at the outlet of the turboexpander generator 112. The second temperature is lower than the first temperature of the hydrogen gas at the inlet of the turboexpander generator 112. For example, the turboexpander generator 112 may output hydrogen gas at temperatures as low as −40° C. In some cases, the turboexpander generator 112 may output hydrogen gas at temperatures below −40° C., such as −86.1° C. (−123° F.) or lower. In some embodiments, the output temperature of the hydrogen gas from the turboexpander generator 112 is a function, in part, of the inlet characteristics of the hydrogen gas, such as the inlet temperature and inlet pressure to the turboexpander generator 112.

[0023] The outlet temperature can be controlled by the design of the turbine wheel of the turboexpander generator 112, which will be described in more detail below. The turboexpander generator 112, and particularly the turbine wheel of the turbine section, is configured (alone or in combination with additional valves in the exemplary system 100) to reduce the pressure of the hydrogen gas to a range between a maximum specified pressure and a minimum specified pressure at a temperature between a maximum specified temperature and a minimum specified temperature. The maximum and minimum specified temperatures may vary. In some embodiments, the exemplary hydrogen dispensing system 100 operates to dispense hydrogen gas within the SAE J2601 standard for hydrogen fueling, maintaining the safety limits of the storage system of the vehicle being filled (e.g., vehicle 115). The SAE J2601 standard specifies the output characteristics of hydrogen gas from the system (e.g., dispenser 114) as including a minimum temperature of −40° C., a maximum temperature of 85° C., and a maximum dispenser pressure of 87.5 megapascals (MPa) (12,589 psig). During a refueling operation, the temperature and pressure of the hydrogen gas changes as it travels from the dispenser to the destination tank, and SAE J2601 defines safe minimum and maximum temperatures and pressures for hydrogen gas in a vehicle storage container, such as a container in a vehicle 115. The turboexpander generator 112 is designed to output hydrogen gas at a specified output temperature (e.g., −40° C.) and output pressure (e.g., 500 psig), or within an acceptable output temperature (e.g., −40° C. to 85° C.) and output pressure (e.g., less than 87.5 MPa), such as the tolerances within the SAE J2601 standard. The depressurized hydrogen gas from the turboexpander generator 112 can be diverted through a fluid path 118 to a dispenser 114 downstream of the turboexpander generator 112 in preparation for dispensing.

[0024] The exemplary hydrogen dispensing system 100 includes, for example, a process control system 120 for monitoring and controlling the flow of hydrogen gas through the hydrogen dispensing system 100. The process control system 120 controls the electric chiller 110, the turboexpander generator 112, or both, to provide hydrogen gas at a desired output temperature at the dispenser 114. For example, the temperature and / or pressure of the hydrogen gas output at the dispenser 114 may be controlled by the process control system 120 to be between minimum and maximum threshold temperatures and / or minimum and maximum threshold pressures, for example. The process control system 120 includes a controller 122 and one or more sensors disposed along the fluid path 118. In the exemplary hydrogen dispensing system 100, the sensors include a first sensor 124 between the storage tank 104 and the chiller 110, a second sensor 126 between the chiller 110 and the turboexpander generator 112, and a third sensor 128 between the turboexpander generator 112 and the dispenser 114. Each of the first sensor 124, the second sensor 126, and the third sensor 128 may include a pressure sensor, a temperature sensor (e.g., a thermocouple), or both a pressure sensor and a temperature sensor, and measure the pressure and / or temperature of the hydrogen gas at a respective location along the fluid path 118.

[0025] The controller 122 is communicatively coupled to the sensors (124, 126, 128), the electric chiller 110, and / or the turboexpander generator 112, and, in some cases, the control valve 116, and can control the cooling capacity of the electric chiller 110 based on measurements of hydrogen gas from one or more of the sensors 124, 126, 128. The process control system 120 controls the operation of the electric chiller 110 to output hydrogen gas from the dispenser 114, for example, at a particular output temperature or at a temperature below an output temperature threshold. The controller 122 can determine the minimum cooling capacity (if any) of the electric chiller 110 based on the measured parameters of the hydrogen gas from one or more of the sensors 124, 126, 128. For example, the third sensor 128 can measure the temperature of the hydrogen gas exiting the turboexpander generator 112, and in response to the measured temperature, the process control system 120 can adjust the amount of pre-cooling applied to the hydrogen gas by the electric chiller 112. In some examples, a first sensor 124 measures a first pressure of hydrogen gas upstream of the electric chiller 110, a second sensor 126 measures a second pressure of hydrogen gas upstream of the turboexpander generator 112, and a third sensor measures a third pressure of hydrogen gas downstream of the turboexpander generator. In response to the measured first pressure, the measured second pressure, and the measured third pressure, the process control system 120 can adjust the cooling capacity of the electric chiller 110 to control the temperature of the hydrogen gas downstream of the chiller 110. In some cases, the process control system 120 is communicatively connected to a pressure sensing system of a hydrogen mobility vehicle, e.g., vehicle 115, being filled at the dispenser 114, and controls the electric chiller 110 in response to pressure data from the pressure sensing system of the vehicle 115. In one example, the process control system 120 receives inputs such as onboard pressure, hydrogen gas pressure upstream of the turboexpander generator 112, hydrogen gas pressure downstream of the turboexpander generator 112, hydrogen gas temperature upstream of the electric chiller 110, or a combination of these inputs, and adjusts the cooling capacity of the electric chiller 110 to control the temperature of the hydrogen gas at the outlet of the chiller 110 and / or the turboexpander generator 112.For example, the temperature drop of the hydrogen gas exiting the turboexpander generator 112 can be determined from known values ​​of the on-board vessel pressure, the upstream hydrogen pressure, and the hydrogen temperature into the turboexpander 112 .

[0026] 1 , the turboexpander generator 112 provides power to the electric chiller 110. In some cases, the turboexpander generator 112 provides some or all of the generated power to different components within or outside of the system 100, such as the electrical components of the dispenser 114, a battery, another electrical component, or a power grid. The power grid may be a municipal grid, a microgrid, a local grid, or other grid. In some embodiments, the turboexpander generator 112 may provide power to the dispenser 114, other equipment at the filling station or parts of the filling station itself (e.g., lighting, buildings, or other components), and other equipment in the process between the storage vessel 102 and the dispenser 114. The turboexpander generator 112 may include power electronics that receive, control, and distribute the generated power from the generator portion of the turboexpander generator 112, for example, using a variable speed drive.

[0027] 1, the gas dispensed is hydrogen gas. In some cases, the type of gas in the storage tank 104 is varied. For example, the gas may include hydrogen, oxygen, air, or a combination thereof. In some cases, the example hydrogen dispensing system 100 may include multiple storage tanks 104 for one or more gas types. The example hydrogen dispensing system 100 may include other components for vehicle or other container filling operations.

[0028] 2 is a schematic diagram of an example turboexpander generator system 200 connected to electrical components 240. The example turboexpander generator system 200 may be used in the example turboexpander generator 112 of FIG. 1 to receive a flow of hydrogen gas from the storage tank 104 or the electric chiller 110, reduce the pressure and temperature of the hydrogen gas, and output the hydrogen gas at a lower temperature and pressure.

[0029] The turboexpander generator system 200 includes a turboexpander generator 202 in parallel with a pressure control valve 230. However, the exemplary turboexpander generator system 200 can omit the pressure control valve 230 and the parallel fluid path 270; instead, the turboexpander generator 202 can receive all of the gas flow 220 from the fluid path. The turboexpander generator 202 is axially positioned such that the turboexpander generator 202 can be installed in-line with piping, such as the fluid path 118 of FIG. 1 . The turboexpander generator 202 functions as a generator by converting kinetic energy from gas expansion through a turbine wheel 204 into rotational energy to generate electrical energy. For example, rotation of the turbine wheel 204 can be used to rotate a rotor 208 within a stator 210, thereby generating electrical energy.

[0030] The turboexpander generator 202 includes a high-performance, high-speed permanent magnet generator that integrates a radial-inflow expansion turbine wheel 204 with low-loss active magnetic bearings (AMBs) 216a,b. The rotor assembly includes a permanent magnet section of the turbine wheel 204 mounted directly to a rotor hub of a rotor 208. The rotor 208 is levitated by the magnetic bearing system, for example, at the longitudinal ends (e.g., axial ends) of the rotor 208, creating a frictionless (or nearly frictionless) interface between the dynamic and static components. The AMBs 216a,b facilitate lossless (or nearly lossless) rotation of the rotor 208.

[0031] The turboexpander generator 202 is designed to allow gas to flow through the system, thereby cooling the generator section and eliminating the need for auxiliary cooling equipment. In some embodiments, the power electronics 218 of the turboexpander generator 202 integrates a variable speed drive (VSD) 232 and a magnetic bearing controller (MBC) 234 into a single cabinet. The VSD 232 allows the turboexpander generator 202 to generate and distribute clean, uniform electrical power to the electrical components 240. For example, the VSD 232 adjusts the frequency and / or amplitude of the generated current to match that of the electrical components 240. After expansion, the hydrogen gas exits the turboexpander generator 202 via the same axial path to a downstream process, such as a filling operation at the dispenser 114 of the exemplary hydrogen dispensing system 100 of FIG. 1 .

[0032] The turboexpander generator 202 includes a flow-through configuration. In the flow-through configuration, gas can flow from an inlet side of the turboexpander generator 202 to an outlet side of the turboexpander generator 202. The gas enters the turbine wheel 204 through a radial gas inlet 254 and exits the turbine wheel 204 through an axial gas outlet 256. The gas then flows through the generator and exits through an outlet 252, where it rejoins the fluid path 270. Generally, the high-pressure hydrogen gas 220 is directed to enter the turboexpander generator 202 through a flow control system 226. The flow control system 226 includes a flow or mass control valve and an emergency shut-off valve. In an embodiment, the turboexpander housing 212 is hermetically sealed. For example, the turboexpander housing 212 is hermetically sealed to the piping between the housing 212. The turboexpander housing 212 may be hermetically sealed to an inlet pipe leading to the turboexpander generator 202 and to an outlet pipe leading away from the turboexpander generator 202. In certain cases, the example turboexpander generator system 200 excludes the flow control system 226 and the control valves.

[0033] The high-pressure hydrogen gas 220 is expanded by passing through the turbine wheel 204, resulting in a pressure reduction of the hydrogen gas. Lower-pressure hydrogen gas 228 exits the turboexpander generator 202. The expansion of the high-pressure hydrogen gas 220 through the turbine wheel 204 causes the turbine wheel 204 to rotate, which in turn rotates the rotor 208. The rotation of the rotor 208 within the stator 210 generates electrical energy. The turboexpander generator 202 achieves the desired pressure reduction and extracts energy from the pressure reduction to generate electricity. In some embodiments, a pressure control valve 230, such as a conventional pressure regulator, is installed in parallel with the turboexpander generator 202. The pressure control valve 230 can be used to control the pressure of the hydrogen gas passing through the turboexpander generator 202. Excess high-pressure hydrogen gas not routed to the turboexpander generator 202 can be routed through the pressure control valve 230.

[0034] The turboexpander generator 202 includes a turbine wheel 204. While the turbine wheel 204 is shown as a radial-inflow turbine wheel, other configurations, such as an axial-flow turbine wheel, are within the scope of this disclosure. In this example, high-pressure hydrogen gas 224 is received from an inlet conduit 250 in the housing 212 and enters a radially oriented inlet 254 of the turbine wheel 204. In certain embodiments, the fluid flows through the inlet conduit 250 and is diverted by a flow diverter 258 to a radial inlet 254 that directs the flow to the radial inlet of the turbine wheel 204. In the example turboexpander generator 202 of FIG. 2 , the flow diverter 258 includes a conical nose that divertes the gas flow radially outward toward the radial inlet 254. The flow divider 258 may be connected to or integrally formed with the bearings 216 a and sensors 217 a on the inlet side of the turboexpander generator 202 and their supports that surround the axial ends of the rotor 208 on the inlet side of the turboexpander generator 202. After expansion, the lower pressure hydrogen gas exits the turbine wheel 204 through an axially oriented outlet 256 to an outlet conduit 252 in the housing 212 at the outlet end of the turboexpander generator 202.

[0035] The turbine wheel 204 may be directly secured to the rotor 208 or an intermediate common shaft, for example, by fasteners, a rigid drive shaft, welding, or other methods. For example, the turbine wheel 204 may be received at one axial end of the rotor 208 and held to the rotor 208 by a shaft. The shaft is threaded into the rotor 208 at one end and captures the turbine wheel 204 at the other end between one end of the rotor 208 and a nut threaded onto the shaft. The turbine wheel 204 and rotor 208 are connected without a gearbox and rotate at the same speed. In other cases, the turbine wheel 204 may be indirectly connected to the rotor 208, for example, by a gear train, a clutch mechanism, or other methods.

[0036] The turbine wheel 204 includes a plurality of turbine wheel blades 206 that extend outward from a hub and react with the expanding process gases to rotate the turbine wheel 204. Figure 2 illustrates an unshrouded turbine wheel in which the turbine blades 206 each have an exposed, generally radially oriented blade tip that extends between a radial inlet 254 and an axial outlet 256. As described in more detail below, the blade tips are substantially sealed against a shroud 214 inside the housing 212. In certain cases, the turbine wheel 204 is a shrouded turbine wheel.

[0037] In a configuration with an unshrouded turbine wheel 204, the housing 212 includes an inwardly facing shroud 214 that is in close proximity to the turbine wheel blades 206 but generally does not contact the turbine wheel blades 206 during operation. The close proximity of the turbine wheel blades 206 and the shroud 214 substantially seals the passage of hydrogen gas between the turbine wheel blades 206 and the shroud 214 as the hydrogen gas flows through the turbine wheel 204. While some amount of gas may leak or pass between the turbine wheel blades 206 and the shroud 214, this leakage is not significant to the operation of the turbine wheel 204. In certain cases, leakage may be comparable to other similar unshrouded turbine / shroud surface interfaces using conventional tolerances between the turbine wheel blades 206 and the shroud 214. The amount of allowable leakage may be predetermined. The operating parameters of the turbine generator may be optimized to reduce leakage. In an embodiment, the housing 212 is hermetically sealed to prevent process gases from leaking out of the radial inlet 254 of the turbine wheel 204 .

[0038] The shroud 214 may be spaced a predetermined distance from the turbine wheel blades 206 and is maintained at that distance from the turbine wheel blades 206 during operation of the turboexpander generator 202 using a magnetic positioning device including active magnetic bearings and position sensors.

[0039] Bearings 216a and 216b are positioned to rotatably support rotor 208 and turbine wheel 204 relative to stator 210 and shroud 214. Turbine wheel 204 is supported in a non-cantilevered manner by bearings 216a and 216b. In embodiments, turbine wheel 204 may be supported in a cantilevered manner, and bearings 216a and 216b may be positioned on the outlet side of turbine wheel 204. In certain cases, one or more of bearings 216a or 216b may include a ball bearing, a needle bearing, a magnetic bearing, a foil bearing, a journal bearing, or other bearing type.

[0040] Bearings 216a and 216b may be a combination radial and thrust bearing that provides radial and axial support for rotor 208. Other configurations may also be used. Bearings 216a and 216b do not have to be the same type of bearing.

[0041] In embodiments where bearings 216a and 216b are magnetic bearings, a magnetic bearing controller (MBC) 234 is used to control magnetic bearings 216a and 216b. Position sensors 217a, 217b may be used to detect the position or change in position of turbine wheel 204 and / or rotor 208 relative to housing 212 or other reference point (e.g., a predetermined value). Position sensors 217a, 217b are directly or indirectly connected to housing 212, and may detect axial and / or radial displacement of rotor 208 and its connected components (e.g., turbine wheel 204) relative to housing 212. Magnetic bearings 216a and / or 216b may respond to information from position sensors 217a, 217b and adjust the detected displacement, if necessary. The MBC 234 may receive information from the position sensors 217a, 217b, process the information, and provide control signals to the magnetic bearings 216a, 216b. The MBC 234 may communicate with various components of the turboexpander generator 202 via a communication channel 262.

[0042] The turboexpander generator 202 can operate without the need for seals (e.g., without the need for dynamic seals) by using the magnetic bearings 216a, 216b and position sensors 217a, 217b to maintain and / or adjust the position of the turbine wheel blades 206 so that they are in close proximity to the shroud 214. The use of active magnetic bearings 216a, b in the turboexpander generator 202 eliminates physical contact between rotating and stationary components and also eliminates the need for lubrication, lubrication systems, and seals.

[0043] Turboexpander generator 202 may include one or more backup bearings. For example, the bearings may be used to rotatably support turbine wheel 204 during startup and shutdown, or during a power outage that affects the operation of magnetic bearings 216a and 216b. Backup bearings may include ball bearings, needle bearings, journal bearings, etc.

[0044] As previously described, the turboexpander generator 202 is configured to generate electricity in response to the rotation of the rotor 208. In certain cases, the rotor 208 may include one or more permanent magnets connected to the rotor 208, for example, on a radially outer surface of the rotor 208 adjacent the stator 210. The stator 210 may include, for example, multiple conductive coils disposed adjacent to the magnets on the rotor 208. Electric current is generated by the rotation of the magnets within the coils of the stator 210. The rotor 208 and the stator 210 may be configured as a synchronous permanent magnet multi-phase alternating current (AC) generator. The electrical output 260 may be, for example, a three-phase output. In certain cases, the stator 210 may include multiple coils (e.g., three or six coils for a three-phase AC output). As the rotor 208 rotates, a voltage is induced in the stator coils. In either case, the magnitude of the voltage induced in the coil is proportional to the rate at which the magnetic field surrounding the coil changes over time (i.e., the rate at which the magnetic field passes on both sides of the coil). When the rotor 208 is connected to rotate at the same speed as the turbine wheel 204, the turboexpander generator 202 is configured to generate electricity at that speed. Such a turboexpander generator 202 is referred to as a "high speed" turbogenerator. For example, in an embodiment, the turboexpander generator 202 can generate up to 135 kilowatts (kW) at a continuous speed of the rotor 208 of 25,000 revolutions per minute (rpm). In an embodiment, the turboexpander generator 202 can generate in the order of 315 kW at a certain rotational speed (e.g., in the order of 23,000 rpm).

[0045] In some embodiments, the design of the turbine wheel 204, rotor 208, and / or stator 210 may be based on desired parameters of the output gas from the turboexpander generator 202. For example, the design of the rotor 208 and stator 210 may be based on a desired temperature of the gas 228 at the input of the turboexpander generator 202, the output of the turboexpander generator 202, or both. The turboexpander generator 202 outputs reduced pressure hydrogen gas at an output temperature that is lower than the input hydrogen gas temperature. For example, the turboexpander generator 202 can output hydrogen gas at temperatures as low as −185° C. (−238° C.). The outlet temperature may be controlled by the design of the turbine wheel 204. For example, the desired output temperature may be achieved by designing the outer diameter of the stator 210 and / or outlet nozzle 252, the inner diameter of the stator 210 and / or outlet nozzle 252, the outer diameter of the rotor 208, the outer diameter of the exducer eye tip of the turbine wheel blades 206, the outer diameter of the exducer eye root of the turbine wheel blades 206, the exit angle from the stator 210, the entry angle into the rotor 208, the exducer root angle, the exducer tip angle, the depth of the channel at the radial inlet 254 of the rotor 208, other features, or a combination of these features. In some examples, varying and determining these geometries and parameters can alter the isentropic efficiency of the pressure reduction to a desired efficiency, which affects the outlet temperature such that a higher isentropic efficiency results in a lower exit temperature and a lower isentropic efficiency results in a higher exit temperature.

[0046] 2, the turboexpander generator 202 is connected to power electronics 218. The power electronics 218 includes a variable speed drive (VSD) 232 (or variable frequency drive) and a magnetic bearing controller (MBC) 234 (discussed above).

[0047] The electrical output 260 of the turboexpander generator 202 is connected to a VSD 232, which can be programmed for specific power requirements. The VSD 232 can include an insulated-gate bipolar transistor (IGBT) rectifier 236 that converts the variable frequency high voltage output from the turboexpander generator 202 to direct current (DC). The rectifier 208 can be a three-phase rectifier for three-phase AC input current. An inverter 238 converts the DC from the rectifier to AC for supply to electrical components 240, such as an electric chiller, a battery, or a power grid. The inverter 238 can convert the DC to 380 VAC to 480 VAC at 50-60 Hz for supply to the components. The specific output of the VSD 232 depends on the power grid and application. Other conversion values ​​are within the scope of this disclosure. VSD 232 samples the voltage and frequency of electrical component 240 and changes the output voltage and frequency of inverter 238 to match the sampled voltage and frequency, thereby matching its output to electrical component 240 (e.g., a chiller, a power grid, a battery, etc.). The output of VSD 232 may be electrically connected to a load of component 240, such as a power grid, to provide power to the power grid. For example, the power grid may include a microgrid for example of example hydrogen dispensing system 100 of FIG. 1 or a microgrid on the premises of example hydrogen dispensing system 100 to provide power to equipment within or connected to example hydrogen dispensing system 100.

[0048] The turboexpander generator 202 is also connected to the MBC 234 within the power electronics 218. The MBC 234 constantly monitors the position, current, temperature, and other parameters of the turboexpander generator 202 and the active magnetic bearings 216a and 216b to ensure they are operating as desired. For example, the MBC 234 is connected to position sensors 217a and 217b to monitor the radial and / or axial position of the turbine wheel 204 and rotor 208. The MBC 234 can control the magnetic bearings 216a and 216b to selectively vary the stiffness and damping characteristics of the magnetic bearings 216a and 216b as a function of spin speed. The MBC 234 can also control desynchronization, including auto-balancing control, adaptive vibration control, adaptive vibration cancellation, and unbalanced force cancellation control. When the exemplary turboexpander generator system 200 is incorporated into the exemplary hydrogen dispensing system 100 of FIG. 1 , the power electronics 218 including the MBC 234 may be communicatively connected to or integrated with the power control system 120, for example, to control the operation of the turboexpander generator 202.

[0049] 3 is a flow diagram illustrating an example method 300 for cooling hydrogen gas in a hydrogen dispensing system, performed, for example, by the example hydrogen dispensing system 100 of FIG. 1. At 302, a flow of hydrogen gas from a hydrogen storage tank is received at an inlet of a turboexpander generator. At 304, the turboexpander generator reduces the pressure and temperature of the hydrogen gas. At 306, the hydrogen gas is output from the turboexpander generator to a hydrogen dispenser. Before the turboexpander generator receives the hydrogen gas, or after the hydrogen gas is output from the turboexpander generator, an electric chiller further cools the hydrogen gas flow from the hydrogen storage tank or turboexpander generator.

[0050] Accordingly, the specification and drawings should be regarded in an illustrative rather than a restrictive sense. Moreover, the use of the aforementioned embodiment and other exemplary language does not necessarily refer to the same embodiment or identical example, but may refer to different, distinct, and potentially identical embodiments. In the foregoing specification, a detailed description has been given with reference to certain exemplary embodiments. It will be apparent, however, that various modifications and changes can be made thereto without departing from the broad spirit and scope of the present disclosure as set forth in the appended claims.

Claims

1. receiving a flow of hydrogen gas from a hydrogen storage tank at an inlet of a turboexpander generator; reducing the pressure and temperature of the hydrogen gas in the turboexpander generator; and outputting the hydrogen gas from the turboexpander generator toward a hydrogen dispenser; A method comprising:

2. Reducing the pressure and temperature of the hydrogen gas in the turboexpander generator includes: directing said flow of hydrogen gas to a turbine wheel of said turboexpander generator; driving rotation of the turbine wheel with the flow of hydrogen gas; and generating an electric current by a generator of the turboexpander generator in response to rotation of the turbine wheel; The method of claim 1 , comprising:

3. 3. The method of claim 2, further comprising supplying the generated electrical current from the turboexpander generator to an electric chiller fluidly connected to the turboexpander generator, the electric chiller configured to cool the flow of hydrogen gas.

4. The method of claim 2 further comprising directing the generated electrical current from the turboexpander generator to power electronics.

5. the power electronics including a variable speed drive connected to the turboexpander generator; directing the generated current to the power electronics includes converting the generated current by the variable speed drive to an alternating current compatible with a power grid. The method of claim 4.

6. The method of claim 1 , wherein outputting the hydrogen gas from the turboexpander generator to a hydrogen dispenser comprises outputting the hydrogen gas at a desired output temperature.

7. 10. The method of claim 1, further comprising cooling the flow of hydrogen gas from the hydrogen storage tank to the inlet of the turboexpander generator with an electric chiller fluidly connected to the turboexpander generator.

8. 8. The method of claim 7, wherein cooling the flow of hydrogen gas with the electrically powered chiller comprises controlling the electrically powered chiller with a controller of a process control system.

9. measuring the temperature of the hydrogen gas stream from the outlet of the turboexpander generator with a temperature sensor in the process control system; controlling the electric chiller with the controller of the process control system includes controlling the electric chiller based on a measured temperature of the hydrogen gas flow from the outlet of the turboexpander generator. The method of claim 8.

10. measuring the pressure of the hydrogen gas flow to the inlet of the turboexpander generator or the hydrogen gas flow from the outlet of the turboexpander generator with a pressure sensor in the process control system; and measuring the temperature of the hydrogen gas stream upstream of the electrically operated chiller with a temperature sensor in the process control system; further comprising Controlling the electric chiller with the controller of the process control system includes controlling the electric chiller based on the measured pressure from the pressure sensor and the measured temperature from the temperature sensor. The method of claim 8.

11. a hydrogen storage tank for storing hydrogen gas; a turboexpander generator fluidly connected to the hydrogen storage tank, the turboexpander generator receiving the flow of hydrogen gas from the hydrogen storage tank to an inlet of the turboexpander generator, the turboexpander generator configured to reduce the pressure and temperature of the flow of hydrogen gas; a dispenser fluidly connected to an outlet of the turboexpander generator, the dispenser configured to receive the flow of hydrogen gas from the outlet of the turboexpander generator; A hydrogen dispensing system comprising:

12. The turboexpander generator is a turbine wheel configured to receive the flow of hydrogen gas and rotate in response to expansion of the hydrogen gas flowing through its inlet and outlet; a rotor connected to the turbine wheel and configured to rotate with the turbine wheel; a stationary stator in which the turboexpander generator generates alternating current due to rotation of the rotor within the stator; The hydrogen dispensing system of claim 11 , comprising:

13. The hydrogen dispensing system of claim 12 further comprising a power electronics system electrically connected to an electrical output of the turboexpander generator and receiving alternating current from the turboexpander generator.

14. 14. The hydrogen dispensing system of claim 13, wherein the power electronics system includes a variable speed drive connected to the electrical output of the turboexpander generator, the variable speed drive converting the alternating current received from the turboexpander generator into alternating current compatible with a power grid.

15. 12. The hydrogen dispensing system of claim 11, further comprising an electric chiller fluidly connected to the turboexpander generator between the hydrogen storage tank and the turboexpander generator, the electric chiller configured to cool the flow of hydrogen gas.

16. 15. The hydrogen dispensing system of claim 14, wherein an electric chiller is electrically connected to the turboexpander generator, the turboexpander generator configured to supply generated alternating current to the electric chiller.

17. 16. The hydrogen dispensing system of claim 15, further comprising a process control system communicatively coupled to the electric chiller and including a controller for controlling the electric chiller.

18. 20. The hydrogen dispensing system of claim 17, wherein the process control system further includes a temperature sensor on an outlet side of the turboexpander generator, the temperature sensor measuring a temperature of the flow of hydrogen gas from the outlet of the turboexpander generator, and the process control system configured to control the electric chiller based on the measured temperature from the temperature sensor.

19. the process control system a pressure sensor for measuring the pressure of the hydrogen flow to the inlet of the turboexpander generator or the hydrogen flow from the outlet of the turboexpander generator; a temperature sensor measuring the temperature of the hydrogen stream upstream of the electric chiller; further comprising The process control system is configured to control the electric chiller based on the measured pressure from the pressure sensor and the measured temperature from the temperature sensor.

18. The hydrogen dispensing system of claim 17.

20. cooling the flow of hydrogen gas from the hydrogen storage tank with an electric chiller; receiving the cooled hydrogen gas stream from the electric chiller at an inlet of a turboexpander generator; reducing the temperature of the cooled hydrogen gas in the turboexpander generator; and outputting the hydrogen gas from the turboexpander generator toward a hydrogen dispenser; A method comprising:

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