Cooling Arrangement Using An Electrochemical Cell

Abstract

An example generator cooling arrangement includes an electrochemical hydrogen pump configured to receive and adjust a fluid containing hydrogen and to provide a refined supply of hydrogen. An electric power generator receives the supply of hydrogen. The refined supply of hydrogen is used to remove thermal energy from the electric power generator.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of U.S. patent application Ser. No. 13/991,789, filed Jun. 5, 2013, which is a 371 National Phase Patent Application based on PCT/US10/62132, filed Dec. 27, 2010, the contents of each of which is incorporated herein by reference, in its entirety.

TECHNICAL FIELD

[0002] This disclosure relates to an electrochemical cell and, more particularly, to using an electrochemical cell to adjust a flow of hydrogen used as a coolant.

BACKGROUND

[0003] Hydrogen is commonly used as a cooling fluid. Some electrical power generators communicate hydrogen through their windings to remove thermal energy from the generator. Hydrogen is particularly useful for this application due to its high heat capacity and relatively low density. Using hydrogen as a cooling fluid is particularly prevalent in large generators, such as generators configured to provide more than 150 megawatts of power.

[0004] Some devices that utilize hydrogen as a cooling fluid receive the hydrogen directly from a stored hydrogen supply, such a storage tank. The stored hydrogen supply must be periodically refilled, which is costly and inefficient. The stored hydrogen onsite is also a safety concern. The flow of hydrogen from the stored hydrogen supply can also carry moisture into the generator, particularly when the hydrogen supply is not optimized to meet the demand for hydrogen. The moisture can crack retaining rings and other components in the generator. Some electrical power generators receive a flow of hydrogen directly from an electrolyzer rather than a hydrogen supply. The electrolyzer produces hydrogen as needed. As known, electrolyzers are costly and require significant capital cost to implement. For all of these reasons, it is desirable to reduce the amount of hydrogen required while still supplying hydrogen having an appropriate pressure, temperature, and purity to efficiently cool the electric power generator.

SUMMARY

[0005] An example generator cooling arrangement includes an electrochemical hydrogen pump configured to receive and adjust a fluid containing hydrogen and to provide a refined supply of hydrogen. An electric power generator receives the supply of hydrogen. The refined supply of hydrogen is used to remove thermal energy from the electric power generator.

[0006] An example electrochemical hydrogen pump is configured to receive a fluid containing hydrogen and to provide a refined supply of hydrogen cooling fluid that is used to remove thermal energy from a device.

[0007] An example electric power generator cooling method includes providing a refined supply of hydrogen using an electrochemical cell and communicating the refined supply of hydrogen to an electric power generator. The method removes thermal energy from the electric power generator using the refined supply of hydrogen.

[0008] These and other features of the disclosed examples can be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE FIGURES

[0009] FIG. 1 shows a highly schematic view of an example cooling arrangement that includes an electrochemical hydrogen pump.

[0010] FIG. 2 shows a schematic view of an example generator cooling arrangement that includes an electrochemical cell.

[0011] FIG. 3 shows a detailed schematic view of the FIG. 2 electrochemical cell.

DETAILED DESCRIPTION

[0012] Referring to FIG. 1, an example cooling arrangement 10 includes an electrochemical hydrogen pump 14 and a hydrogen cooled device 18. A fluid communicates from the hydrogen cooled device 18 along a path 22 to the electrochemical hydrogen pump 14. The electrochemical hydrogen pump 14 provides a refined supply of hydrogen to the hydrogen cooled device 18 along a path 34. The refined supply of hydrogen provided along the path 34 comprises the hydrogen purified within the electrochemical hydrogen pump 14.

[0013] After moving through the path 34, the refined supply of hydrogen moves through the hydrogen cooled device 18. In this example, the refined supply of hydrogen moves thermal energy away from the hydrogen cooled device 18 along a path 26. The thermal energy is exhausted to the surrounding environment at 30. Alternatively, thermal energy moves away from the hydrogen cooled device 18 carried by the fluid moving along the path 22.

[0014] In this example, the electrochemical hydrogen pump 14 purifies hydrogen from the fluid received from the path 22 to provide the refined supply of hydrogen. When purifying hydrogen from the fluid received from the path 22, the electrochemical hydrogen pump 14 recycles hydrogen that has already moved through the hydrogen cooled device 18. That is, the electrochemical hydrogen pump 14 purifies hydrogen in the fluid and communicates it back to the hydrogen cooled device 18 along the path 34. The impurities present in the fluid from path 22 along with some hydrogen, are vented from the electrochemical hydrogen pump 14 through a vent 36.

[0015] In addition to purifying hydrogen from the fluid, the example electrochemical hydrogen pump 14 is also configured to regulate the pressure of the supply of hydrogen provided to the hydrogen cooled device 18 along the path 34. The example path 34 passes through a pressure regulator device 40, which typically consists of a control valve and a pressure gauge in a single device. The electrochemical hydrogen pump 14 evolves hydrogen at almost any pressure desired. It takes more electric power to generate higher pressures. In one example, a device (not shown) provides the desired back pressure on the electrochemical hydrogen pump 40, which includes cells designed to operate at the desired pressure, to result in the pressure desired.

[0016] Purifying hydrogen from the fluid and regulating the pressure are examples of how the example electrochemical hydrogen pump 14 refines the fluid. In another example, the electrochemical hydrogen pump 14 controls the temperature of the refined fluid.

[0017] The example hydrogen cooled device 18 is also configured to selectively receive hydrogen directly from a hydrogen supply 32. When needed, the hydrogen communicates from the hydrogen supply 32 to the hydrogen cooled device 18 along a path 38. The hydrogen cooled device 18 receives hydrogen from the hydrogen supply 32 if the electrochemical hydrogen pump 14 is not able to provide sufficient hydrogen to the hydrogen cooled device 18 (e.g., during system start-up). The example electrochemical hydrogen pump 14 is only able to provide sufficient hydrogen to the hydrogen cooled device 18 if there is sufficient hydrogen in the fluid moving along the path 22. Due to leaks in the hydrogen-coolant loop and venting from the electrochemical hydrogen pump 14 some make-up hydrogen will be periodically required, which is provided by the hydrogen supply 32.

[0018] Referring to FIG. 2 with continuing reference to FIG. 1, in one example, the electrochemical hydrogen pump 14 of a cooling arrangement 10a includes an electrochemical cell 14a that includes an electrolyte, such as a polymer electrolyte membrane that can selectively transport hydrogen ions, or protons. The electrochemical cell 14a is configured to purify hydrogen from the fluid provided to the electrochemical cell 14a along a path 22a. The electrochemical cell 14a then communicates the refined hydrogen purified from the flow of fluid along a path 34a to an electric power generator 18a, which is a type of hydrogen cooled device 18. Impurities are vented from the electromechanical cell 14a at vent 36a.

[0019] Within the electric power generator 18a, the refined hydrogen absorbs thermal energy, particularly from windings of the electric power generator 18a. A person having skill in this art and the benefit of this disclosure would understand how to utilize a flow of hydrogen to remove thermal energy from the electric power generator 18a.

[0020] Hydrogen that has moved through the electric power generator 18a communicates from the electric power generator 18a back to the electrochemical cell 14a along a path 22a. As can be appreciated, the fluid communicating along the path 22a includes hydrogen as well as impurities and other elements that are picked up from the electric power generator 18a, for example, or components of air that diffuse into the hydrogen system.

[0021] Thermal energy is communicated away from the electric power generator 18a along the path 26a and is exhausted to the surrounding environment at 30a. Thermal energy is also carried away from the electric power generator 18a in the fluid communicating along the path 22a.

[0022] The example cooling arrangement 10 includes a hydrogen control system 32a, such as a Proton Energy Stableflow.RTM. system, and a hydrogen storage tank 32b. The hydrogen control system 32a and the hydrogen storage tank 32b are examples of the hydrogen supply 32 in FIG. 1.

[0023] The hydrogen control system 32a and the hydrogen storage tank 32b provide hydrogen directly to the electric power generator 18a along the path 38b. In this example, a valve 54 selectively communicates a supply of hydrogen from the hydrogen storage device 32b when the electric power generator 18a needs additional hydrogen. The hydrogen control system 32a monitors the properties of the hydrogen fluid in the electric power generator 18a; these properties may include: purity, temperature, and pressure. The hydrogen control system 32a controls the valve 54. In this manner, the hydrogen control system 32a and the hydrogen storage tank 32b selectively provide hydrogen to the electric power generator if the electrochemical cell 14a is not able to provide sufficient hydrogen, for example.

[0024] Various devices may be used as the hydrogen storage device 32b. For example, a supply of hydrogen may be stored in high pressure cylinders or a low pressure tank. Both such devices would function as the hydrogen storage device 32b. Alternatively, the hydrogen supply can consist of an electrolyzer that generates hydrogen on site from water or both an electrolyzer and hydrogen tanks.

[0025] In one example, a controller 56 monitors the purity of the hydrogen within the electric power generator 18a, such as the purity of hydrogen within a casing of the electric power generator. The controller 56 also monitors the pressure of the hydrogen within the electric power generator 18a. The controller 56 is in communication with the electrochemical cell 14a and is configured to adjust the hydrogen moving away from the electrochemical cell 14a depending on the purity and the pressure of hydrogen within the electric power generator 18a. The controller 56 can be part of the hydrogen control system 32a. Adjustments may include providing more fluid to the electrochemical cell 14a, increasing the rate and/or pressure of the hydrogen generated by the electrochemical cell 14a, and/or improving the purity of the hydrogen generated by the electrochemical cell 14a. The adjustments enable the electrochemical cell 14a to provide a higher rate of refined hydrogen, a higher hydrogen purity, or refined hydrogen at a different pressure.

[0026] In one example, hydrogen communicating along the path 34a moves through a dryer (not shown), which dries the hydrogen prior to its entry into the electric power generator 18a. Drying the hydrogen ensures that the hydrogen entering the electric power generator 18a has a very low dew point, for example.

[0027] Referring now to FIG. 3 within continuing reference to FIG. 2, the example electrochemical cell 14a includes multiple individual cells 58 arranged in a stack. Each cell 58 includes an anode plate 62 and a cathode plate 66 on opposing sides of a membrane electrode assembly 70. The electrochemical cell 14a receives electrical power from a power supply 68 to the end plates 60 (only one shown) of the electrochemical cell 14a.

[0028] In each of the example cells 58, the anode plate 62 and cathode plate 66 are porous structures that are filled with water and permit water to be transported through the plates, but act as barriers to gas transport through the plates. The membrane electrode assembly 70 includes a polymer electrolyte membrane 74 positioned between catalyst layers 78 and 82.

[0029] The example individual cell 58 has an optional solid separator plate 86 between the anode plate 62 and the cathode plate 66. The solid plate 86 may be a separate element or it may be an integral part of either anode plate 62 or cathode plate 66. The individual cells 58 may also include a cooler plate (not shown).

[0030] A cathode side diffusion layer 90 is arranged between the cathode plate 66 and the membrane electrode assembly 70. An anode side gas diffusion layer 94 is arranged between the anode plate 62 and the membrane electrode assembly 70.

[0031] In this example, a unitized electrode assembly 98 of the cell 58 comprises the cathode side gas diffusion layer 94, the anode side gas diffusion layer 90, and the membrane electrode assembly 70.

[0032] The flow of fluid is provided to the electrochemical cell 14a and moves through anode channels 102. The gas diffusion layer 94 distributes some of the flow of fluid from the anode channels 102 to the catalyst layer 82. In this example, the fluid moving along the path 22a provides the fluid that is distributed to the catalyst layer 82.

[0033] Within the cell 58, hydrogen (from the path 22a) is electrochemically oxidized to protons at the catalyst layer 82 nearest the anode plate 62 and the electrons flow through the anode plate 62. The protons are transported through the membrane 74 and are then electrochemically recombined with other protons and electrons provided by the cathode plate 66 to generate hydrogen gas at the catalyst layer 78 nearest the cathode plate 66. The electrons from the cathode plate 66 are provided by either the anode plate immediately adjacent or by the power supply 68 (for the cathode end cell, not shown). As can be appreciated, the evolving hydrogen is more concentrated, or refined, than the hydrogen communicated along the path 22a. The evolving hydrogen is communicated away from the electrochemical cell 14a through a plurality of channels 106.

[0034] In the middle of the plates 62 and 66 are coolant channels 108 that communicate water through the cell assemblies. These coolant channels 108 can either be part of the anode plate 62, the cathode plate 66, or both. They can also be established in the optional solid separator plate 86.

[0035] Again, in this example, both the anode plate 62 and the cathode plate 66 operate as water transport plates, which are porous structures that permit water to be transported through the plates but act as a barrier to gas since the plates are kept filled by water flowing in the coolant channels 108. In this example, the water flowing in the coolant channels 108 is maintained at a pressure that is slightly lower than the pressure of the gases in anode channels 102 and cathode channels 106. This ensures that any excess liquid water in the gases in these channels is drawn into the porous plates. At the same time, if these gases are not fully saturated with water vapor then the porous plates provide a means to saturate these gases by transporting water vapor into the gases by diffusion. The saturated gases in the channels 102 and 106 prevent the membrane 74 from drying out and this results in a membrane that has the lowest possible resistance to proton transport, as well as maximizing the membrane lifetime.

[0036] In this example, the water flowing through the channels 108 is provided by a coolant loop 112 external to the cell assembly 14a. This example coolant loop 112 has a pump 116 to provide both the flow and pressure desired and may also include a heat exchanger 120 to help maintain the cell temperature desired since some heat is generated by the cells. Alternatively, this coolant heat exchanger may be larger to also remove thermal energy from the incoming fluid 22a, if desired. (In other words, the electrochemical hydrogen pump may be used to provide hydrogen of the desired purity, pressure, and temperature required by using this coolant loop to as a means to remove both the thermal energy of the cells and the electric power generator.)

[0037] Other examples (not shown) may include only the anode plate 62 or the cathode plate 66 operating as porous water transport plates with the other plate being a solid plate. For example, a preferred configuration may be only the anode plate 62 is porous and the cathode plate 66 is solid. In this case, the coolant channels 108 should be in communication with the anode plate 62, by either being part of the anode plate 62 (as shown) or being on the back of the anode plate 62 or being contained in a solid plate (either 66 or 86) with the channels on the side adjacent to the porous anode plate 62. This configuration will ensure that the gas on the anode side is kept well saturated, which is especially important because the protons generated on the anode 82 will drag water as they are transported through the membrane 74 and will therefore keep the membrane well hydrated. It is not as critical to have a water source on the cathode side of the cell where hydrogen is generated. An additional advantage of this configuration is that there is a solid barrier between the anode channels 102 and the cathode channels 106, which may allow for a larger pressure difference between these two gas streams and enable hydrogen gas to be generated at higher pressures than a cell with all water transport plates.

[0038] Another example (not shown) may include having no separate coolant channels 108 and instead water is circulated through the cathode plate channels 106. In this case, hydrogen will be evolved into the circulating liquid water. In this case, the anode plate 62 and the cathode plate 66 can be either porous water transport plates or solid plates. This cell configuration is simple and should keep the membrane 74 well hydrated; however, a liquid-gas separator is then required downstream of the cell assembly 14a (on path 34a in FIG. 2) in order to separate the pure hydrogen from the liquid water stream. Dryers (not shown) will also be required to ensure that the hydrogen delivered to the electric power generator 18a is sufficiently dry.

[0039] Features of the disclosed examples include an electric power generator, or another hydrogen cooled device, having improved efficiencies over previous designs due to cooling utilizing hydrogen having an appropriate pressure and purity. The amount of hydrogen required is reduced and emissions from the electric power generator are also reduced as no excess hydrogen is provided.

[0040] The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims.

Claims

1. A generator cooling arrangement, comprising: an electrochemical hydrogen pump comprising a polymer electrolyte membrane through which hydrogen ions are transported, an anode plate having anode channels and a cathode plate having cathode channels, at least one of the anode plate and the cathode plate having coolant channels through which the polymer electrolyte membrane is hydrated, the coolant channels connected to a coolant loop, wherein the electrochemical hydrogen pump is configured such that a pressure of water flowing in the coolant channels is maintained at a lower pressure than a pressure of a gas in either of the anode channels or the cathode channels of the electrochemical hydrogen pump during operation, and wherein the electrochemical hydrogen pump is configured to receive and adjust a fluid stream containing gaseous hydrogen, and to provide a refined supply of hydrogen in a more refined state than the fluid stream received by the electrochemical hydrogen pump; an electric power generator that receives the refined supply of hydrogen, wherein the refined supply of hydrogen is used to remove thermal energy from the electric power generator, and wherein impurities are introduced into the refined supply of hydrogen as the refined supply of hydrogen is used to remove the thermal energy from the electric power generator via direct contact of the refined supply of hydrogen with the electric power generator, wherein the electrochemical hydrogen pump receives the fluid stream containing gaseous hydrogen with impurities entrained therein from the electric power generator; and a vent in fluid communication with the electrochemical hydrogen pump to vent the impurities.

2. The generator cooling arrangement of claim 1, wherein the electrochemical hydrogen pump is configured to adjust the fluid stream including gaseous hydrogen by increasing the hydrogen concentration in the provided, refined supply of hydrogen relative to the received fluid stream containing gaseous hydrogen.

3. The generator cooling arrangement of claim 2, wherein the refined supply of hydrogen comprises hydrogen purified from the fluid stream containing gaseous hydrogen.

4. The generator cooling arrangement of claim 1, wherein the electrochemical hydrogen pump is configured to adjust the fluid stream by changing the pressure of the fluid stream.

5. The generator cooling arrangement of claim 1, wherein the refined supply of hydrogen comprises at least some of the fluid stream.

6. The generator cooling arrangement of claim 1, wherein the electric power generator is configured to generate more than 150 megawatts of electric power.

7. The generator cooling arrangement of claim 1, wherein the electric power generator comprises windings and the refined supply of hydrogen removes thermal energy from the windings.

8. The generator cooling arrangement of claim 1, wherein the electrochemical hydrogen pump is configured to communicate the refined supply of hydrogen to a hydrogen storage device that stores the refined supply of hydrogen, and the electric power generator is configured to receive the refined supply of hydrogen from the hydrogen storage device.

9. A cooling system, comprising: an electrochemical hydrogen pump comprising a polymer electrolyte membrane, an anode plate having anode channels and a cathode plate having cathode channels, at least one of the anode plate and the cathode plate having coolant channels through which the polymer electrolyte membrane is hydrated; a hydrogen cooled device in fluid communication with the electrochemical hydrogen pump via a first path and a second path, wherein the electrochemical hydrogen pump receives a supply of hydrogen with impurities entrained therein from the hydrogen cooled device along the second path, the electrochemical hydrogen pump removing and venting the impurities to provide a refined supply of hydrogen that is communicated to the hydrogen cooled device along the first path, wherein impurities and heat are introduced into the refined supply of hydrogen via contact with the hydrogen cooled device; and an exhaust outlet in fluid communication with the hydrogen cooled device for exhausting a portion of heat entrained in the refined supply of hydrogen after moving through the hydrogen cooled device.

10. The cooling system of claim 9 further comprising: a hydrogen supply in fluid communication with the hydrogen cooled device via a third path, wherein the hydrogen supply supplies an initial amount of hydrogen to the hydrogen cooled device along the third path, the initial amount of hydrogen moving through the hydrogen cooled device wherein heat and impurities are entrained therein, wherein the initial amount of hydrogen containing the heat and impurities is communicated to the electrochemical hydrogen pump along the second path and the electrochemical hydrogen pump vents the impurities to provide the refined supply of hydrogen.

11. The cooling system of claim 9 wherein the coolant channels are connected to a coolant loop.

12. The cooling system of claim 11 wherein electrochemical hydrogen pump is configured such that a pressure of coolant flowing in the coolant channels is maintained at a lower pressure than a pressure of a gas in either of the anode channels or the cathode channels of the electrochemical hydrogen pump during operation.

13. The cooling system of claim 11 wherein the coolant loop further comprises a heat exchanger in fluid communication with the electrochemical hydrogen pump, the supply of hydrogen with impurities entrained therein including a portion of the thermal energy removed from the hydrogen cooled device, wherein the heat exchanger removes at least some of the portion of thermal energy from the supply of hydrogen with impurities entrained therein, which was removed from the hydrogen cooled device.

14. The cooling system of claim 9 further comprising: a hydrogen control system in communication with the hydrogen cooled device, the hydrogen control system monitoring at least one of purity, temperature, and pressure of the refined stream of hydrogen, the hydrogen control system including a controller in communication with the electrochemical hydrogen pump and the hydrogen cooled device, wherein the controller adjusts, via the electrochemical hydrogen pump, a corresponding at least one of purity, temperature, and pressure of the refined stream of hydrogen in the hydrogen cooled device based at least in part on the monitoring.

15. A generator cooling arrangement, comprising: an electrochemical hydrogen pump comprising a polymer electrolyte membrane, an anode plate having anode channels and a cathode plate having cathode channels, at least one of the anode plate and the cathode plate having coolant channels through which the polymer electrolyte membrane is hydrated, the electrochemical hydrogen pump being configured to receive and adjust a fluid stream containing gaseous hydrogen, and to provide a refined supply of hydrogen; an electric power generator that receives the refined supply of hydrogen, wherein the refined supply of hydrogen is used to remove thermal energy from the electric power generator, wherein impurities are introduced into the refined supply of hydrogen as the refined supply of hydrogen is used to remove the thermal energy from the electric power generator, and wherein the electrochemical hydrogen pump receives the fluid stream containing gaseous hydrogen with impurities entrained therein from the electric power generator and removes the impurities by passing hydrogen ions through a polymer electrolyte membrane to provide the refined supply of hydrogen.

16. The generator cooling arrangement of claim 15 further comprising: a vent in fluid communication with the electrochemical hydrogen pump to vent the impurities.

17. The generator cooling arrangement of claim 15 wherein the coolant channels are connected to a coolant loop, and wherein the electrochemical hydrogen pump is configured such that a pressure of coolant flowing in the coolant channels is maintained at a lower pressure than a pressure of a gas in either of the anode channels or the cathode channels of the electrochemical hydrogen pump during operation.

18. The generator cooling arrangement of claim 15 wherein a first one of the anode and cathode plates is solid and a second one of the anode and cathode plates is porous, the second one of the anode and cathode plates including the coolant channels.

19. The generator cooling arrangement of claim 15 wherein the electrochemical hydrogen pump is configured to regulate a pressure and a temperature of the refined supply of hydrogen.

20. The generator cooling arrangement of claim 15 further comprising: a controller in communication with the electrochemical hydrogen pump and the electric power generator, the controller monitoring at least one of a purity and a pressure of hydrogen within the electric power generator and configured to adjust a corresponding at least one of the purity and the pressure of the refined supply of hydrogen based at least in part on the monitoring.

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