Hydrogen energy storage system based on reversible solid oxide cell

Abstract

This application discloses a hydrogen energy storage system based on a reversible solid oxide battery, comprising: a battery stack module including a first inlet, a second inlet, a first outlet, and a second outlet; a hydrogen storage device connected to the first inlet; a high-temperature steam generator connected to the first inlet; an air input device connected to the second inlet; a first cooling device connected to the first outlet; a gas-liquid separation device connected to the first cooling device, the first inlet, and the hydrogen storage device; and a second cooling device connected to the second outlet. This hydrogen energy storage system can be applied to high-temperature electrolysis hydrogen production and directly to hydrogen-oxygen reaction power generation. The piping arrangement under both conditions is highly coupled, enabling rapid online switching between conditions. Furthermore, the system is simple in structure and easy to operate, significantly improving the efficiency of condition switching and achieving efficient, clean, and reversible conversion between chemical and electrical energy, thus contributing to peak shaving and valley filling in the power system.

Description

Technical Field

[0001] This application relates to the field of new energy technology, and in particular to a hydrogen energy storage system based on a reversible solid oxide battery. Background Technology

[0002] With advancements in renewable energy generation technology and the increasing economies of scale, the proportion of renewable energy power is continuously rising. Wind power, solar power, and other renewable energy sources can enhance the efficiency of the power grid system to some extent. However, due to the discontinuous and volatile nature of wind and solar power generation, large-scale grid connection will directly affect the stability and reliability of the power system, impacting the grid and affecting its normal operation. Therefore, they usually need to be used in conjunction with energy storage and regulation systems. Hydrogen is an excellent energy storage medium. It features high energy density, is green and environmentally friendly, and its energy form is not limited by spatial location during storage. Hydrogen energy storage has been explicitly included in new energy storage technologies.

[0003] Solid oxide batteries (SOCs) are green and highly efficient all-solid-state electrochemical energy conversion devices that can achieve efficient conversion between chemical energy and electrical energy. Specifically, they can operate in two different modes: electrolysis and power generation. The combination of these two modes enables the conversion between electrical energy and chemical energy and back to electrical energy, i.e., hydrogen energy storage. Traditional hydrogen energy storage systems based on solid oxide batteries suffer from problems such as low operating mode switching efficiency, low fuel utilization rate, and high system cost. Summary of the Invention

[0004] The purpose of this application is to address at least one of the aforementioned technical defects, particularly the technical defects of low operating condition switching efficiency, low fuel utilization rate, and high system cost in existing hydrogen energy storage systems.

[0005] This application provides a hydrogen energy storage system based on a reversible solid oxide battery, comprising:

[0006] The fuel cell module includes a first inlet, a second inlet, a first outlet, and a second outlet. It is used to produce hydrogen by electrolyzing water under the first operating condition and to generate electricity using oxygen and hydrogen under the second operating condition.

[0007] A hydrogen storage device, connected to the first inlet, is used to supply hydrogen to the first inlet under the second operating condition;

[0008] A high-temperature steam generator is connected to the first inlet and is used to supply steam to the first inlet under the first operating condition.

[0009] An air input device, connected to the second inlet, is used to supply air to the second inlet under both the first and second operating conditions.

[0010] A first cooling device, connected to a first outlet, is used to cool a first mixed gas output from the first outlet; the first mixed gas includes hydrogen and water vapor.

[0011] The gas-liquid separation device is connected to the first cooling device, the first inlet and the hydrogen storage device respectively, and is used to separate the first mixed gas after cooling. The separated hydrogen flows into the first inlet for circulation and into the hydrogen storage device for storage under the first operating condition, and flows into the first inlet for circulation under the second operating condition.

[0012] The second cooling device, connected to the second outlet, is used to cool and discharge the oxygen-rich air generated in the fuel cell module under the first operating condition, and to cool and discharge the oxygen-deficient air generated in the fuel cell module under the second operating condition.

[0013] In one embodiment, the hydrogen energy storage system further includes a circulating hydrogen pressurization device, which is disposed between the gas-liquid separator and the first inlet, for pressurizing the circulating hydrogen.

[0014] In one embodiment, the high-temperature steam generator produces steam at a temperature of 150°C to 200°C and a pressure of 3 barg.

[0015] In one embodiment, the circulating hydrogen pressurization device is a reciprocating compressor or a liquid ring compressor.

[0016] In one embodiment, the hydrogen energy storage system further includes an ejector. The outlet of the ejector is connected to a first inlet. The primary inlet of the ejector is connected to a high-temperature steam generator and a hydrogen storage device, respectively. The secondary inlet of the ejector is connected to a gas-liquid separator. The ejector is used to, under a first operating condition, mix and pressurize the steam generated by the high-temperature steam generator as the primary stream and the circulating hydrogen separated by the gas-liquid separator as the secondary stream, and then deliver it to the first inlet. It is also used to, under a second operating condition, mix and pressurize the hydrogen delivered by the hydrogen storage device as the primary stream and the circulating hydrogen separated by the gas-liquid separator as the secondary stream, and then deliver it to the first inlet.

[0017] In one embodiment, the high-temperature steam generator produces steam at a temperature of 150°C to 200°C and a pressure of 6 barg.

[0018] In one embodiment, the reaction temperature of the fuel cell module is 600°C to 750°C.

[0019] In one embodiment, the hydrogen storage device includes a hydrogen compressor and a hydrogen storage tank;

[0020] The hydrogen compressor is connected to the gas-liquid separator and the hydrogen storage tank respectively, and is used to pressurize the hydrogen delivered from the gas-liquid separator and then deliver it to the hydrogen storage tank for storage.

[0021] The hydrogen storage tank is connected to the first inlet and is used to supply hydrogen to the first inlet under the second operating condition.

[0022] In one embodiment, the first cooling device cools the first mixed gas to 20°C to 40°C before delivering it to the gas-liquid separator.

[0023] In one embodiment, the second cooling device cools the oxygen-rich air or oxygen-deficient air to 40°C to 60°C before discharging it.

[0024] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0025] This hydrogen energy storage system can be directly applied to both high-temperature electrolysis hydrogen production and hydrogen-oxygen reaction power generation. The piping layouts for both conditions are highly coupled, with essentially identical gas flow paths, enabling rapid online switching between conditions. Its simple structure and convenient operation significantly improve switching efficiency. Furthermore, it maintains hydrogen circulation under different conditions. In the first condition, hydrogen is used as a protective gas, while in the second condition, unconsumed hydrogen is recycled back into the fuel cell module, effectively improving the fuel utilization rate of hydrogen and increasing the overall power generation efficiency of the system. Because hydrogen circulates throughout the system, the traditional SOFC power generation system's step of mixing and burning products from the first and second outlets is eliminated. This also effectively reduces the system's maximum operating temperature, lowers the difficulty and cost of selecting system equipment and piping materials, and improves system stability and economy. This hydrogen energy storage system achieves efficient, clean, and reversible conversion between chemical and electrical energy, and can be applied in the smart grid field to achieve peak shaving and valley filling, as well as large-scale renewable energy conversion and storage, improving the reliability and stability of the power energy system. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a hydrogen energy storage system provided in one embodiment of this application;

[0028] Figure 2 A schematic diagram of the structure of a hydrogen energy storage system provided in another embodiment of this application;

[0029] Figure 3 This is a schematic diagram of the structure of a hydrogen energy storage system provided in another embodiment of this application. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] This application provides a hydrogen energy storage system based on a reversible solid oxide battery. Please refer to [link to relevant documentation]. Figure 1 It includes a high-temperature steam generator 10, an air input device 20, a fuel cell module 30, a first cooling device 40, a second cooling device 50, a gas-liquid separation device 60, and a hydrogen storage device 70.

[0032] The fuel cell module 30 serves as the reaction site for the hydrogen energy storage system. It contains a reversible solid oxide battery and is equipped with electric heaters, heat exchangers, and other devices to control the reaction temperature. The fuel cell module 30 can operate under two conditions. In the first condition, the module uses direct current from the external power grid to electrolyze water vapor, producing oxygen and hydrogen at the electrodes of the solid oxide battery. In the second condition, the oxygen and hydrogen undergo an oxidation reaction to generate electricity, which is then fed into the power grid. The switching between the first and second conditions can be initiated by the power grid dispatch center. When the power generation in the grid is excessive, the hydrogen energy storage system can be instructed to operate in the first condition, using the excess electricity to electrolyze water vapor and converting it into hydrogen, which is stored in the hydrogen storage device 70. When the load on the power grid is excessive, the system can be instructed to operate in the second condition, reacting the stored hydrogen with oxygen in the air to generate electricity, which is then fed into the power grid. The hydrogen energy storage system can switch between the first and second operating conditions, which can reduce the load shedding burden on other generator sets and help the power system to shave peak loads and fill valleys.

[0033] The fuel cell module 30 has two external interfaces: a first inlet, a second inlet, a first outlet, and a second outlet. The first inlet is connected to a high-temperature steam generator 10. Under a first operating condition, the high-temperature steam generator 10 generates high-temperature steam, which is then introduced into the fuel cell module 30 through the first inlet. This steam serves as the raw material for the water electrolysis reaction. The high-temperature steam generator 10 and the first inlet can be connected via a first switching valve. Under the first operating condition, the first switching valve is opened; under the second operating condition, it is closed. During the hydrogen electrolysis process, hydrogen and oxygen are generated at two isolated electrodes, thus preventing mixing. Hydrogen flows out through the first outlet, and oxygen flows out through the second outlet. The first inlet and the first outlet are connected, and the hydrogen produced by electrolysis will flow out through the first outlet along with any unconsumed steam. The second inlet and the second outlet are also connected. The second inlet is connected to the air input device 20. Although the elements in the air are not required as raw materials in the first operating condition, air still needs to be supplied to the fuel cell module 30 in the first operating condition. This is because using air as a purging gas can reduce the oxygen partial pressure and promote the electrochemical reaction. Continuously supplying air in the first operating condition can dilute the pure oxygen produced by electrolysis of water vapor and discharge it from the second outlet after becoming oxygen-rich air.

[0034] The first cooling device 40 is connected to the first outlet. Under the first operating condition, the first mixed gas formed by the hydrogen gas generated by water electrolysis and the unconsumed water vapor will be sent to the gas-liquid separator 60 after being cooled by the first cooling device 40.

[0035] The outlet of the gas-liquid separator 60 is connected to the first inlet and the hydrogen storage device 70, respectively, for gas-liquid separation of the cooled first mixed gas. Under the first operating condition, the separated hydrogen flows into the first inlet for circulation and into the hydrogen storage device 70 for storage. That is, the gas-liquid separator 60 can separate hydrogen and liquid droplets in the first mixed gas. Since hydrogen is lighter, it will be located at the top of the gas-liquid separator 60, splitting it into two paths. Under the first operating condition, one path flows back to the first inlet, where the circulating hydrogen plays a protective role in the electrolysis of water vapor. The other path flows into the hydrogen storage device 70 for storage. This is equivalent to converting the electrical energy provided by the external power grid into the chemical energy of the hydrogen and storing it in the hydrogen storage device 70, to be used as a raw material for power generation under the second operating condition. Furthermore, since the gas flow direction of the gas-liquid separator 60 differs between the first and second operating conditions, for ease of control, a second switching valve can be installed on the pipeline between the gas-liquid separator 60 and the first inlet, and a third switching valve can be installed on the pipeline between the gas-liquid separator 60 and the hydrogen storage device 70. In the first operating condition, both the second and third switching valves are opened simultaneously. In the second operating condition, the second switching valve is opened and the third switching valve is closed. The liquid separated by the gas-liquid separator 60 can be recycled back to the high-temperature steam generator after impurity removal and used as a raw material for generating steam.

[0036] The first inlet is also connected to a hydrogen storage device 70. In the second operating condition, the hydrogen storage device 70 supplies the high-pressure hydrogen stored within it to the first inlet as a raw material for power generation using a solid oxide battery. The hydrogen storage device 70 and the first inlet can be connected via a fourth switching valve. In the first operating condition, the fourth switching valve is closed; in the second operating condition, it is opened. During the reaction between hydrogen and oxygen in the fuel cell module 30, water vapor is produced. A first mixed gas containing the water vapor produced by the reaction and unreacted hydrogen flows out from the first outlet. The second inlet is connected to an air input device 20. The oxygen contained in the air input through the air input device 20 is consumed as a reaction raw material, and the resulting oxygen-deficient air is discharged from the second outlet.

[0037] The first cooling device 40 is connected to the first outlet. Under the second operating condition, the first mixed gas formed by the water vapor generated by the reaction and the unreacted hydrogen will be sent to the gas-liquid separator 60 after being cooled by the first cooling device 40.

[0038] The gas-liquid separation device 60 is used to separate the first mixed gas after cooling. The separated hydrogen flows into the first inlet for circulation under the second operating condition. At this time, the separated hydrogen is the hydrogen that was not completely consumed in the previous reaction. It is recycled back into the fuel cell module 30 to continue to be used as a reaction raw material, which greatly improves the utilization rate of raw materials.

[0039] The hydrogen energy storage system in this embodiment can be directly applied to both high-temperature electrolysis hydrogen production and hydrogen-oxygen reaction power generation. The piping arrangements under both conditions are highly coupled, with essentially identical gas flow paths, enabling rapid online switching between operating conditions. Furthermore, its simple structure and convenient operation significantly improve switching efficiency. The system maintains hydrogen circulation under different conditions. In the first condition, hydrogen is used as a protective gas, while in the second condition, unconsumed hydrogen is recycled back into the fuel cell module 30 for reaction, effectively improving the fuel utilization rate of hydrogen and increasing the overall power generation efficiency of the system. Because hydrogen circulates throughout the system, the traditional SOFC power generation system's step of mixing and burning the products from the first and second outlets is eliminated. This also effectively reduces the system's maximum operating temperature, lowers the difficulty and cost of selecting system equipment and piping materials, and improves system stability and economy. This hydrogen energy storage system can achieve efficient, clean, and reversible conversion between chemical and electrical energy, and can be applied in the smart grid field to achieve peak shaving and valley filling, as well as large-scale renewable energy conversion and storage, improving the reliability and stability of the power energy system.

[0040] In one embodiment, please refer to Figure 2 The hydrogen energy storage system also includes a circulating hydrogen pressurization device 80, which is located between the gas-liquid separator 60 and the first inlet to pressurize the circulating hydrogen. To ensure better circulation of hydrogen in the pipeline, the circulating hydrogen is pressurized by the circulating hydrogen pressurization device 80 and then delivered to the first inlet. In some embodiments, the circulating hydrogen pressurization device 80 can be a liquid ring compressor or a reciprocating compressor. A reciprocating compressor is a compressor in which a crankshaft drives a piston to generate high-pressure gas in a compression cylinder. When the crankshaft reciprocates, the intake valve opens first and the exhaust valve closes, allowing intake gas to enter the compression cylinder through the intake valve. Then, the intake valve closes, the piston moves, reducing the volume of the compression cylinder and compressing the gas. Afterward, the exhaust valve opens, discharging the high-pressure gas. A liquid ring compressor is a rotary compressor. Its main components are an eccentrically mounted impeller and a cylinder filled with liquid. When the impeller rotates, the liquid is pushed against the cylinder wall by centrifugal force, forming a liquid ring. A series of closed cavities are formed between the liquid ring and the impeller. As the cavities pass through the intake end, they connect to the intake pipe, drawing in gas. The volume of each cavity changes during the rotation of the liquid ring, compressing the internal gas. As the cavities pass through the exhaust end, they connect to the exhaust pipe, discharging gas. The liquid ring compressor has a simple structure and exhibits low exhaust pulsation and noise, making it more suitable for the hydrogen energy storage system in this embodiment.

[0041] In one embodiment, the high-temperature steam generator 10 produces steam at a temperature of 150°C to 200°C and a pressure of 3 barg. It is understood that the high-temperature steam generator may include a heating source, a pressure detection unit, and a temperature detection unit. To ensure the reaction is not affected by impurities, pure water can be input into the high-temperature steam generator under the first operating condition. The heating source evaporates the water into steam. The outputs of the pressure and temperature detection units are then used to determine whether the requirements are met. When the requirements are met, the first switching valve is opened, supplying steam to the first inlet. To ensure the steam pressure meets the requirements, a steam pressurization unit can also be installed in the steam pressurization device.

[0042] In one embodiment, please refer to Figure 3 The hydrogen energy storage system also includes an ejector 90. The outlet of the ejector 90 is connected to the first inlet. The primary inlet of the ejector 90 is connected to both the high-temperature steam generator 10 and the hydrogen storage device 70. The secondary inlet of the ejector 90 is connected to the gas-liquid separator 60. The ejector 90 is used in the first operating condition to mix and pressurize the steam generated by the high-temperature steam generator 10 (primary stream) and the circulating hydrogen separated by the gas-liquid separator 60 (secondary stream) before supplying it to the first inlet. It is also used in the second operating condition to mix and pressurize the hydrogen supplied by the hydrogen storage device 70 (primary stream) and the circulating hydrogen separated by the gas-liquid separator 60 (secondary stream) before supplying it to the first inlet. It can be understood that the ejector 90 is a device that can use a high-speed gas flow to eject a low-speed gas flow, and the gas flow rate is related to the pressure. Because the circulating hydrogen has a low pressure and low flow rate, it cannot effectively enter the fuel cell module 30. The high-temperature steam generator requires a certain pressure to generate steam, resulting in a high-speed gas flow compared to the circulating hydrogen. In the first operating condition, the steam is used to entrain the circulating hydrogen, and the two mix within the ejector 90, improving the hydrogen's protective effect. The hydrogen storage device 70 stores hydrogen at high pressure, also at a high speed compared to the unpressurized circulating hydrogen. In the second operating condition, the high-pressure hydrogen in the hydrogen storage device 70 is used to entrain the circulating hydrogen, and the two mix within the ejector 90, allowing any unconsumed hydrogen to be recycled back into the fuel cell module 30 for further reaction.

[0043] In one embodiment, the high-temperature steam generator 10 produces steam at a temperature of 150°C to 200°C and a pressure of 6 barg. It is understood that since the circulating hydrogen is not pressurized when using the ejector 90, steam is required for ejection in the first operating condition, thus necessitating a higher steam pressure.

[0044] In one embodiment, the hydrogen storage device 70 includes a hydrogen compressor and a hydrogen storage tank. The hydrogen compressor is connected to both the gas-liquid separator 60 and the hydrogen storage tank, and is used to pressurize the hydrogen supplied from the gas-liquid separator 60 before delivering it to the hydrogen storage tank for storage. The hydrogen storage tank is connected to a first inlet for supplying hydrogen to the first inlet under a second operating condition.

[0045] In one embodiment, the air input device 20 includes an air compressor or blower, with its inlet connected to the atmosphere and its outlet connected to a second inlet. Air is drawn from the atmosphere, pressurized by the air compressor or blower, and then delivered into the fuel cell stack module. A blower is preferred over an air compressor.

[0046] In one embodiment, the reaction temperature of the fuel cell module 30 is 600°C to 750°C.

[0047] In one embodiment, the first cooling device 40 cools the first mixed gas to 20°C.

[0048] After reaching 40℃, it is transported to the gas-liquid separation device 60.

[0049] In one embodiment, the second cooling device 50 cools the oxygen-enriched or oxygen-deficient air to 40°C to 60°C before discharging it.

[0050] In one embodiment, both the first cooling device 40 and the second cooling device 50 include heat exchangers, which can be plate heat exchangers or shell-and-tube heat exchangers. A plate heat exchanger is a high-efficiency heat exchanger composed of a series of metal plates with a certain corrugated shape stacked together. Thin rectangular channels are formed between the plates, through which heat exchange occurs. A shell-and-tube heat exchanger is a heat exchanger composed of a shell, heat transfer tube bundle, tube sheet, baffles, and tube box. The tube bundle is located inside the shell, and both ends of the tube bundle are fixed to the tube sheet. Cold and hot fluids flow inside and outside the tubes, respectively, and the baffles guide the fluids through the tube bundle multiple times for heat exchange. Plate heat exchangers are more suitable for the hydrogen energy storage system in this embodiment due to their high heat exchange efficiency and more compact structure.

[0051] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0052] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0053] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hydrogen energy storage system based on a reversible solid oxide battery, characterized in that, include: The fuel cell module includes a first inlet, a second inlet, a first outlet, and a second outlet. It is used to produce hydrogen by electrolyzing water under the first operating condition and to generate electricity using oxygen and hydrogen under the second operating condition. Hydrogen storage device; High-temperature steam generator; An air input device, connected to the second inlet, is used to supply air to the second inlet under the first operating condition and the second operating condition; A first cooling device, connected to the first outlet, is used to cool the first mixed gas output from the first outlet; the first mixed gas includes hydrogen and water vapor. A gas-liquid separation device is connected to the first cooling device and the hydrogen storage device respectively, and is used to perform gas-liquid separation on the cooled first mixed gas. The second cooling device is connected to the second outlet and is used to cool and discharge the oxygen-rich air generated in the fuel cell module under the first operating condition, and to cool and discharge the oxygen-deficient air generated in the fuel cell module under the second operating condition. An ejector is provided, with its outlet connected to the first inlet. The primary inlet of the ejector is connected to both the high-temperature steam generator and the hydrogen storage device. The secondary inlet of the ejector is connected to the gas-liquid separator. The ejector is used, under the first operating condition, to mix and pressurize the steam generated by the high-temperature steam generator (primary stream) and the circulating hydrogen separated by the gas-liquid separator (secondary stream) before conveying them to the first inlet. It is also used, under the second operating condition, to mix and pressurize the hydrogen supplied by the hydrogen storage device (primary stream) and the circulating hydrogen separated by the gas-liquid separator (secondary stream) before conveying them to the first inlet.

2. The hydrogen energy storage system based on a reversible solid oxide battery according to claim 1, characterized in that, The high-temperature steam generator produces steam at a temperature of 150℃~200℃ and a pressure of 6 barg.

3. The hydrogen energy storage system based on a reversible solid oxide battery according to any one of claims 1-2, characterized in that, The reaction temperature of the fuel cell module is 600℃~750℃.

4. The hydrogen energy storage system based on a reversible solid oxide battery according to any one of claims 1-2, characterized in that, The hydrogen storage device includes a hydrogen compressor and a hydrogen storage tank; The hydrogen compressor is connected to both the gas-liquid separator and the hydrogen storage tank, and is used to pressurize the hydrogen delivered from the gas-liquid separator and then deliver it to the hydrogen storage tank for storage.

5. The hydrogen energy storage system based on a reversible solid oxide battery according to any one of claims 1-2, characterized in that, The first cooling device cools the first mixed gas to 20°C~40°C and then delivers it to the gas-liquid separation device.

6. The hydrogen energy storage system based on a reversible solid oxide battery according to any one of claims 1-2, characterized in that, The second cooling device cools the oxygen-enriched air or the oxygen-deficient air to 40°C~60°C before discharging it.

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