Solid oxide electrolytic cell hydrogen production system and operation method thereof

Abstract

The invention relates to a solid oxide electrolytic cell hydrogen production system and an operation method thereof. The solid oxide electrolytic cell hydrogen production system comprises an SOEC galvanic pile module, a fan, an air electric heater, a steam superheater, a deionized water pump, a first preheater, a second preheater, a steam generator, a condenser, a high-pressure hydrogen cylinder, a high-pressure protective gas cylinder, a compressed air cylinder, a first electromagnetic valve and a second electromagnetic valve. Wherein the air electric heater is sequentially connected with the water vapor superheater and the SOEC stack module and can be used for heating air and water vapor at an inlet of the SOEC stack module. According to the embodiment of the invention, heating of air and water vapor at the inlet of the SOEC galvanic pile module is met by adopting the air electric heater, so that waste heat of mixed gas at the outlet of the SOEC galvanic pile module is utilized in a gradient manner, the electrolytic hydrogen production efficiency is effectively improved, meanwhile, the power consumption is effectively reduced, and the system is simple in design structure, convenient to realize low-cost manufacturing and suitable for popularization and application. And the high-efficiency and energy-saving electrolytic hydrogen production requirement can be met.

Description

Technical Field

[0001] The present application relates to the technical field of fuel cell systems, and in particular to a solid oxide electrolysis cell hydrogen production system and an operation method thereof. Background Art

[0002] Solid Oxide Electrolysis Cell (SOEC) hydrogen production technology is a highly efficient, green hydrogen production technology. Under applied voltage and high temperature, water vapor is electrolyzed to produce high-purity hydrogen and oxygen, converting electrical and thermal energy into chemical energy.

[0003] At present, the mainstream electrolytic hydrogen production technologies include alkaline electrolysis, proton exchange membrane electrolysis and SOEC electrolysis. From the perspective of technical characteristics, alkaline electrolyzers are suitable for stable power supply scenarios. Currently, the hydrogen production scale of a single electrolyzer can reach 9000A / m 2 5000Nm 3 / hour. Although alkaline electrolyzer technology has the highest degree of industrialization, its reliability and stability in long-term operation still need to be further verified. Proton exchange membrane electrolyzers are highly responsive to fluctuating power supplies, have higher electrical density performance under the same hydrogen production capacity, can maximize the release of power, and have a wide load response range. They are suitable for large-scale hydrogen production scenarios coupled with renewable energy power, but there is a problem of dependence on precious metal materials. Compared with the more common alkaline water electrolysis hydrogen production technology and proton exchange membrane electrolysis hydrogen production technology, SOEC electrolysis hydrogen production has the highest working efficiency and is currently the most efficient water electrolysis technology, but its temperature needs to be above 600°C, which is especially suitable for applications with high-temperature water vapor. Comparing the power consumption of electrolyzers, the current density of alkaline electrolyzers is between 4000-8000A / m 2 Within the range, the DC power consumption is about 4.3-4.6 degrees / cubic meter, and the current density is less than 3000A / m 2 4kWh / Nm can be achieved 3 The following power consumption; Proton exchange membrane electrolyzer MW-level products (200 cubic meters / hour) generally consume about 4.3kWh / Nm 3 Whether it is an alkaline electrolyzer or a proton exchange membrane electrolyzer, when integrated into a system to produce hydrogen, the current large-scale and industrial application of water electrolysis system generally consumes about 5kWh / Nm 3 , and as the operating time increases, the power consumption also increases. The power consumption of SOEC kilowatt-class products can achieve a level of 3.6 degrees. The measured data are: the system electrolysis hydrogen production power of the reversible SOC device of the Shanghai Institute of Applied Physics in the Guangzhou Xiaohu Island Southern Power Grid Energy Storage Project has reached 100kW, and the DC energy consumption of the unit H2 stack is about 3.0kWh / Nm 3 .

[0004] The SOEC hydrogen production system primarily consists of a high-temperature air supply system, a feed gas supply system, an exhaust gas treatment system, and an electronic control system. The air supply system typically uses a combination of a fan and electric heater. The feed gas for SOEC is a mixture of high-temperature water vapor and hydrogen, with the high-temperature water vapor originating from a steam generator and a high-temperature heat exchanger, while the hydrogen comes from external bottled gas or hydrogen generated by the SOEC hydrogen production system itself. Conventional SOEC hydrogen production systems use electric heaters in conjunction with heat exchangers to heat the required air and water vapor, respectively. A single SOEC system requires two sets of electric heaters and high-temperature heat exchangers, resulting in a complex and relatively expensive system. Furthermore, the outlet air temperature of the high-temperature heat exchanger cannot be directly adjusted.

[0005] Therefore, developing a SOEC hydrogen production system with simple system architecture, high system efficiency, stability and reliability plays an important role in the promotion and application of SOEC hydrogen production systems. Summary of the Invention

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0007] The embodiments of the present application provide a solid oxide electrolysis cell hydrogen production system and an operating method thereof, which can improve the efficiency of electrolytic hydrogen production while effectively reducing power consumption. Its design structure is simple and facilitates low-cost manufacturing, thereby meeting the needs of efficient and energy-saving electrolytic hydrogen production.

[0008] This application provides the following technical solutions:

[0009] In the first aspect, an embodiment of the present application provides a solid oxide electrolysis cell hydrogen production system, including a SOEC stack module, a fan, an air electric heater, a steam superheater, a deionized water pump, a first preheater, a second preheater, a steam generator, a condenser, a high-pressure hydrogen cylinder, a high-pressure protective gas cylinder, a compressed air cylinder, a first solenoid valve and a second solenoid valve; the air electric heater is connected to the steam superheater and the SOEC stack module in sequence, and the air electric heater is used to heat the air and steam at the inlet of the SOEC stack module.

[0010] In combination with the first aspect, in an embodiment of the present application, the outlet air temperature of the electric air heater is increased or decreased according to a preset temperature rise rate.

[0011] In combination with the first aspect, in one embodiment of the present application, the outlet of the high-pressure hydrogen cylinder is connected to the cold side outlet of the steam generator and the cold side inlet of the water vapor superheater in sequence. The H2 at the outlet of the high-pressure hydrogen cylinder is mixed with the water vapor at the cold side outlet of the steam generator after being decompressed, and enters the cold side inlet of the water vapor superheater. The flow ratio of the H2 and the water vapor is greater than 1:20, and the H2 is used to maintain a reducing atmosphere on the water vapor side of the SOEC stack module.

[0012] In combination with the first aspect, in one embodiment of the present application, the steam superheater is provided with a hot side inlet, a hot side outlet, a cold side inlet and a cold side outlet, the hot side inlet is connected to the outlet of the air electric heater, the hot side outlet is connected to the air inlet of the SOEC stack module, the cold side inlet is connected to the cold side outlet of the steam generator, and the cold side outlet of the steam superheater is connected to the steam inlet of the SOEC stack module; the air at the outlet of the air electric heater exchanges heat with the steam and H2 at the outlet of the steam generator in the steam superheater.

[0013] In combination with the first aspect, in one embodiment of the present application, the SOEC stack module is connected to the steam generator and the second preheater in sequence, and the air at the outlet of the SOEC stack module enters the hot side channel of the steam generator and the hot side channel of the second preheater in sequence. The hot side channel of the steam generator is used to vaporize the unsaturated water vapor in the steam generator, and the hot side channel of the second preheater is used to increase the saturation of the unsaturated water vapor in the second preheater.

[0014] In combination with the first aspect, in one embodiment of the present application, the H2 and the water vapor at the outlet of the SOEC stack module are used to heat the deionized water in the cold side channel of the first preheater.

[0015] In combination with the first aspect, in one embodiment of the present application, the deionized water pump is connected to the first preheater, the second preheater, the steam generator and the steam superheater in sequence; the deionized water of the deionized water pump enters the first preheater, the second preheater, the steam generator and the steam superheater in sequence, the first preheater is used to convert the deionized water into the deionized water in a steam-water mixed state, the second preheater is used to heat the deionized water in the steam-water mixed state to increase the saturation of water vapor, the steam generator is used to evaporate and gasify the heated deionized water, and the steam superheater is used to heat the evaporated and gasified deionized water mixed with H2.

[0016] In combination with the first aspect, in one embodiment of the present application, the high-pressure protective gas cylinder is provided with a first pipeline and a second pipeline, the first pipeline is used to provide protective gas to the hydrogen production system, and the first solenoid valve is installed on the second pipeline. When the hydrogen production system is running, the first solenoid valve is in a closed state, and when the hydrogen production system stops running, the first solenoid valve is in an open state. After the pressure is reduced, the protective gas enters the steam superheater and the SOEC stack module in sequence to protect the electrode material of the SOEC stack module.

[0017] In combination with the first aspect, in one embodiment of the present application, the second solenoid valve is installed on the pipeline between the outlet pressure regulating valve of the compressed air bottle and the inlet of the air electric heater. When the hydrogen production system is running, the second solenoid valve is in a closed state. When the hydrogen production system stops running, the second solenoid valve is in an open state, and the compressed air enters the air electric heater after being depressurized to protect the air electric heater.

[0018] In a second aspect, an embodiment of the present application provides an operating method for a solid oxide electrolysis cell hydrogen production system, which is applied to the above solid oxide electrolysis cell hydrogen production system, and the method comprises the following steps: (1) keeping the first solenoid valve and the second solenoid valve of the system in a closed state, and turning on the blower of the system, introducing protective gas into the system, and adjusting the flow rate of the protective gas to a first target flow rate, adjusting the speed of the blower to a target speed, turning on the air heater of the system, and adjusting the air flow rate and outlet air temperature of the air heater; (2) when the outlet air temperature of the SOEC stack module of the system reaches 500°C, and the temperature of the water vapor superheater, the steam generator, and the pipeline between the water vapor superheater and the steam generator and the SOEC stack module of the system reaches above 200°C, turning on the deionized water pump of the system, and providing deionized water and H2 to the system, and when the flow rate of the deionized water and the H2 reaches the second target flow rate, reducing the flow rate of the protective gas to 0; when the temperature of the SOEC stack module is in an increasing state, increasing the temperature of the SOEC stack module; The flow rate of deionized water is adjusted to maintain the flow rate ratio of H2 to water vapor at the inlet of the SOEC stack module greater than 1:20; (3) turning on the DC power supply connected to the SOEC stack module, and setting the target voltage value and voltage rise rate, adjusting the flow rate of the deionized water and the H2 at the inlet of the system according to the electrolysis current, and adjusting the air flow rate and temperature at the inlet of the SOEC stack module; (4) when the current of the SOEC stack module reaches the first target value, maintaining the flow rate of the deionized water, the flow rate of the H2 and the water vapor at the inlet of the SOEC stack module greater than 1:20; The air flow rate remains unchanged, and the electrolysis ratio of the water vapor is always maintained at a limit value set by the SOEC stack module during the electrolysis process; (5) when the electrolysis current is 0, the flow rate of the deionized water at the system inlet is reduced to a second target value, and the air flow rate and outlet air temperature of the air electric heater are adjusted at the same time; (6) when the outlet temperature of the SOEC stack module is reduced to 500°C, the protective gas is introduced into the system, and when the flow rate of the protective gas reaches a third target value, the deionized water pump is turned off and the supply of H2 is stopped.

[0019] Compared with the existing technology, the advantages of this application are: the high-temperature air at the outlet of the air electric heater of this system first enters the steam superheater and then enters the air side of the SOEC stack module. The use of the air electric heater meets the heating of the high-temperature air and high-temperature steam at the inlet of the SOEC stack module, and the waste heat of the mixed gas of high-temperature air, high-temperature H2 and water vapor at the outlet of the SOEC stack module is utilized in a cascade manner. This system can improve the efficiency of electrolytic hydrogen production while effectively reducing power consumption. Its design structure is simple, which facilitates low-cost manufacturing, thereby meeting the needs of efficient and energy-saving electrolytic hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0021] Figure 1 This is a schematic diagram of the overall structure of a solid oxide electrolysis cell hydrogen production system provided in an embodiment of the present application;

[0022] Figure numerals: SOEC stack module 1; fan 2; electric air heater 3; steam superheater 4; deionized water pump 5; first preheater 6; second preheater 7; steam generator 8; condenser 9; high-pressure hydrogen cylinder 10; high-pressure protective gas cylinder 11; compressed air cylinder 12; first solenoid valve 13; second solenoid valve 14. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without inventive effort are within the scope of protection of this application.

[0024] It should be noted that although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in an order different from that in the flowchart. The terms "first" and "second" in the specification, claims, and the above-mentioned figures are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limitations of the implementation of this application. Therefore, they have no technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed in this application without affecting the efficacy and purpose of this application. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of the implementation of this application. Changes or adjustments in their relative relationships should also be considered as the scope of the implementation of this application without substantially changing the technical content.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing the embodiments of this application only and are not intended to limit this application.

[0026] The specific implementation of this application will be described below with reference to the accompanying drawings:

[0027] like Figure 1 As shown, Figure 1 It is a schematic diagram of the overall structure of the solid oxide electrolysis cell hydrogen production system provided in an embodiment of the present application, which includes a SOEC stack module 1, a blower 2, an electric air heater 3, a steam superheater 4, a deionized water pump 5, a first preheater 6, a second preheater 7, a steam generator 8, a condenser 9, a high-pressure hydrogen cylinder 10, a high-pressure protective gas cylinder 11, a compressed air cylinder 12, a first solenoid valve 13 and a second solenoid valve 14. Among them, the SOEC stack module 1 refers to a modular structure composed of multiple solid oxide electrolysis cell units. Each SOEC unit is an independent basic unit for high-temperature water electrolysis to produce hydrogen, which can convert electrical energy and thermal energy into chemical energy to realize the electrolysis process of water, thereby producing hydrogen and oxygen. During the operation of the system, the high-temperature air at the outlet of the electric air heater 3 can first enter the steam superheater 4 and then enter the air side of the SOEC stack module 1. The electric air heater 3 can meet the heating needs of the high-temperature air and high-temperature steam at the inlet of the SOEC stack module 1, so that the waste heat of the mixed gas of high-temperature air, high-temperature H2 and water steam at the outlet of the SOEC stack module 1 can be utilized in a cascade manner.

[0028] In one embodiment, the outlet air temperature of the electric air heater 3 can reach 900° C., and the temperature can be increased or decreased at a certain temperature rise rate.

[0029] In one embodiment, the room-temperature, high-pressure H2 at the outlet of the empty high-pressure hydrogen cylinder 10 is decompressed and then mixed with the high-temperature water vapor at the cold-side outlet of the steam generator 8 before the cold-side inlet of the water vapor superheater 4. It is worth noting that the flow ratio of H2 to water vapor should be greater than 1:20. The H2 is primarily used to maintain a high-temperature reducing atmosphere on the water vapor side of the SOEC stack module 1, thereby extending the service life of the electrode materials on the water vapor side.

[0030] In one embodiment, the steam superheater 4 is provided with a hot side inlet, a hot side outlet, a cold side inlet, and a cold side outlet. The hot side inlet is connected to the outlet of the electric air heater 3, the hot side outlet is connected to the air inlet of the SOEC stack module 1, the cold side inlet is connected to the cold side steam outlet of the steam generator 8, and the cold side outlet is connected to the steam inlet of the SOEC stack module 1. During system operation, the high-temperature air at the outlet of the electric air heater 3 exchanges heat with the high-temperature steam and H2 at the outlet of the steam generator 8 in the steam superheater 4, and the air, steam, and H2 at the outlet of the steam generator 8 all meet the temperature requirements of the SOEC stack module 1.

[0031] In one embodiment, the SOEC stack module 1 is connected to the steam generator 8 and the second preheater 7 in sequence. During the operation of the system, the high-temperature air at the outlet of the SOEC stack module 1 can enter the hot side channel of the steam generator 8 and the hot side channel of the second preheater 7 in sequence. The hot side channel of the steam generator 8 can be used to completely vaporize the unsaturated water vapor in the steam generator 8, and the hot side channel of the second preheater 7 can increase the saturation of the unsaturated water vapor in the second preheater 7. The high-temperature air is finally reduced to about 100°C and discharged from the system.

[0032] In one embodiment, the high-temperature H2 and water vapor mixture at the outlet of the SOEC stack module 1 can enter the first preheater 6, and the room-temperature deionized water in the cold side channel of the first preheater 6 is heated to 100°C, thereby realizing the waste heat recovery of the high-temperature H2 and water vapor mixture at the outlet of the SOEC stack module 1, and at the same time providing cooling for the condensation of water vapor in the mixture and the purification of H2.

[0033] In one embodiment, the deionized water pump 5 is sequentially connected to the first preheater 6, the second preheater 7, the steam generator 8, and the steam superheater 4. During system operation, the deionized water at the outlet of the deionized water pump 5 can first enter the first preheater 6, where it is heated from liquid water to 100°C to achieve a steam-water mixed state. It then enters the second preheater 7 for heating to increase the saturation of the water vapor. The water then enters the steam generator 8 for complete evaporation and gasification. It is then mixed with a certain flow of room temperature H2 and enters the steam superheater 4. Finally, it is heated to approximately 700°C and enters the SOEC stack module 1 to undergo an electrolysis reaction.

[0034] In one embodiment, the high-pressure protective gas cylinder 11 is provided with a first pipeline and a second pipeline, wherein the first pipeline is used to provide protective gas to the SOEC hydrogen production system during the heating and cooling processes, and a first solenoid valve 13 is installed on the second pipeline. The solenoid valve is a normally open solenoid valve. When the SOEC hydrogen production system is operating normally, the first solenoid valve 13 is in a closed state. Once the system is stopped suddenly, the first solenoid valve 13 can be automatically opened, and the depressurized protective gas enters the steam superheater 4 and the SOEC stack module 1 in turn to protect the electrode material on the steam side of the SOEC stack.

[0035] In one embodiment, the second solenoid valve 14 is installed in the pipeline between the outlet pressure regulating valve of the compressed air bottle 12 and the inlet of the electric air heater 3. The second solenoid valve 14 is a normally open solenoid valve. When the SOEC hydrogen production system is operating normally, the second solenoid valve 14 is in a closed state. Once the system is shut down suddenly, the second solenoid valve 14 can automatically open, and the compressed air with reduced pressure enters the electric air heater 3 in turn, preventing the electric air heater 3 from overheating and burning out due to power failure of the fan 2.

[0036] In addition, the present application also provides a method for operating a solid oxide electrolysis cell hydrogen production system. The method is applicable to the aforementioned solid oxide electrolysis cell hydrogen production system. That is, the method can be based on the coordinated operation of various components within the system. The specific content may include the following steps:

[0037] (1) In the first heating phase of the SOEC hydrogen production system, the first solenoid valve 13 and the second solenoid valve 14 are kept closed, the fan 2 is turned on, and the protective gas is introduced into the system for purging. At the same time, the flow rate of the protective gas is adjusted to the first target flow rate, the speed of the fan 2 is adjusted to the target speed, the air heater 3 is turned on, and the air flow rate and outlet air temperature of the air heater 3 are adjusted to ensure that the SOEC stack module 1 is heated at a certain temperature rise rate. It should be noted that the SOEC hydrogen production system manual usually gives a recommended range of the protective gas flow rate. For example, the manual of a certain model of SOEC hydrogen production system clearly states that during the heating phase, the protective gas flow rate (i.e., the first target flow rate) should be controlled at 20-30 cubic meters per hour. The value of the target speed is related to the requirements of meeting the first target flow rate of the protective gas, achieving the requirements of effective purging of the system, and ensuring the speed range for safe and stable operation of the equipment.

[0038] (2) SOEC hydrogen production system heating stage 2: When the outlet air temperature of the SOEC stack module 1 reaches 500°C and the temperature of the steam superheater 4, steam generator 8 and the pipes between the two and the SOEC stack module 1 reaches above 200°C, the deionized water pump 5 is turned on to supply a certain flow of deionized water and H2 to the system. After the flow of deionized water and H2 reaches the second target flow, the flow of the protective gas is reduced to 0. As the temperature of the SOEC stack module 1 continues to rise, the flow of deionized water is gradually increased to ensure that the deionized water is completely evaporated before entering the SOEC stack module 1, and the ratio of the H2 flow rate to the water vapor flow rate at the inlet of the SOEC stack module 1 is always maintained at greater than 1:20. When the outlet air temperature of the SOEC stack module 1 gradually rises to the target temperature, the system enters the hot standby stage. It should be noted that the designed operating flow rates of SOEC stack modules, steam superheaters 4, steam generators 8 and other equipment of different specifications and models are different. For example, for some small SOEC hydrogen production systems, the deionized water flow rate (i.e., the second target flow rate) may range from a few milliliters to tens of milliliters per minute, while for large hydrogen production systems, the second target flow rate may reach several liters per minute or even higher. This step can preliminarily determine the flow rate range based on the equipment's manual and design parameters.

[0039] (3) During the hydrogen production stage when the SOEC hydrogen production system gradually increases the electrolysis current, the DC power supply connected to the SOEC stack module 1 is turned on, and the target voltage value and voltage rise rate are set to start the electrolysis hydrogen production process. The flow rates of deionized water and H2 at the system inlet are adjusted according to the electrolysis current, and the air flow rate and temperature at the SOEC stack module 1 inlet are adjusted to ensure that the water vapor utilization rate of the SOEC stack module 1 does not exceed the limit value and the temperature is maintained within an appropriate range. Among them, the target voltage value refers to the target value of the DC power supply output voltage set according to the characteristics of the SOEC stack module, the hydrogen production process requirements, and safety factors in order to achieve an efficient and stable electrolysis hydrogen production reaction during the hydrogen production stage when the SOEC hydrogen production system gradually increases the electrolysis current. Its value range is usually higher than the stack open circuit voltage and lower than the maximum voltage that the stack can withstand. The voltage rise rate refers to the rate at which the DC power supply output voltage changes with time during the process of increasing the electrolysis current to produce hydrogen in the SOEC hydrogen production system. This rate can be determined based on the physical properties, structural stability and hydrogen production efficiency requirements of the SOEC stack module to ensure that the target voltage value is reached as quickly as possible without damaging the stack, thereby achieving efficient hydrogen production.

[0040] (4) During the stage of hydrogen production at rated load by the SOEC hydrogen production system, after the current of the SOEC stack module 1 reaches the first target value, the deionized water flow rate, H2 flow rate, and air flow rate are kept stable, and the electrolysis ratio of water vapor is always kept within the limit value given by the supplier of the SOEC stack module 1 during the electrolysis process. It should be noted that the SOEC stack module 1 has determined its parameters such as the maximum current it can withstand and the optimal operating current range during the design phase. The first target value is usually set within the optimal operating current range of the stack to ensure that the stack performs at its best and prolongs its service life. For example, when the optimal operating current range of the stack design is 50-80A, the first target value can be selected within this range.

[0041] (5) During the phase where the SOEC hydrogen production system gradually reduces the electrolysis current, the voltage of the DC power supply gradually decreases according to the set load reduction rate. After the electrolysis current gradually drops to 0, the flow rate of deionized water at the system inlet is reduced to the second target value. During this period, the air flow rate and outlet air temperature of the air electric heater 3 are adjusted to ensure that the SOEC stack module 1 is within the appropriate temperature range. The second target value is a specific value set for adjusting the flow rate of deionized water at the system inlet after the electrolysis current of the SOEC hydrogen production system drops to 0. In general, its value is related to the minimum flow rate required for safe and stable operation of the system.

[0042] (6) During the cooling phase of the SOEC stack module 1, the air flow rate and outlet air temperature of the air heater 3 are adjusted to ensure that the SOEC stack module 1 is cooled at a certain rate. When the outlet temperature of the SOEC stack module 1 drops to 500°C, a certain flow rate of shielding gas is introduced into the system. When the flow rate of shielding gas reaches a third target value, the deionized water pump 5 is turned off, the H2 supply is stopped, and the system continues to cool down at a certain rate to near room temperature. The third target value is related to the minimum flow rate required for SOEC stack module protection.

[0043] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A solid oxide electrolysis cell hydrogen production system, comprising a SOEC stack module, a blower, an electric air heater, a steam superheater, a deionized water pump, a first preheater, a second preheater, a steam generator, a condenser, a high-pressure hydrogen cylinder, a high-pressure protective gas cylinder, a compressed air cylinder, a first solenoid valve, and a second solenoid valve; the electric air heater is sequentially connected to the steam superheater and the SOEC stack module, and is used to heat the air and steam at the inlet of the SOEC stack module.

2. The solid oxide electrolysis cell hydrogen production system according to claim 1, characterized in that: The outlet air temperature of the electric air heater is increased or decreased according to a preset temperature rise rate.

3. The solid oxide electrolysis cell hydrogen production system according to claim 1, characterized in that: The outlet of the high-pressure hydrogen cylinder is connected to the cold side outlet of the steam generator and the cold side inlet of the water vapor superheater in sequence. The H2 at the outlet of the high-pressure hydrogen cylinder is mixed with the water vapor at the cold side outlet of the steam generator after decompression and enters the cold side inlet of the water vapor superheater. The flow ratio of the H2 and the water vapor is greater than 1:

20. The H2 is used to maintain a reducing atmosphere on the water vapor side of the SOEC stack module.

4. The solid oxide electrolysis cell hydrogen production system according to claim 1, characterized in that: The steam superheater is provided with a hot side inlet, a hot side outlet, a cold side inlet and a cold side outlet. The hot side inlet is connected to the outlet of the air electric heater, the hot side outlet is connected to the air inlet of the SOEC stack module, the cold side inlet is connected to the cold side outlet of the steam generator, and the cold side outlet of the steam superheater is connected to the steam inlet of the SOEC stack module; the air at the outlet of the air electric heater exchanges heat with the steam and H2 at the outlet of the steam generator in the steam superheater.

5. The solid oxide electrolysis cell hydrogen production system according to claim 1, characterized in that: The SOEC stack module is connected to the steam generator and the second preheater in sequence, and the air at the outlet of the SOEC stack module enters the hot side channel of the steam generator and the hot side channel of the second preheater in sequence. The hot side channel of the steam generator is used to vaporize the unsaturated water vapor in the steam generator, and the hot side channel of the second preheater is used to increase the saturation of the unsaturated water vapor in the second preheater.

6. The solid oxide electrolysis cell hydrogen production system according to claim 1, characterized in that: The H2 and the water vapor at the outlet of the SOEC stack module are used to heat the deionized water in the cold side channel of the first preheater.

7. The solid oxide electrolysis cell hydrogen production system according to claim 1, characterized in that: The deionized water pump is connected to the first preheater, the second preheater, the steam generator and the steam superheater in sequence; the deionized water from the deionized water pump enters the first preheater, the second preheater, the steam generator and the steam superheater in sequence, the first preheater is used to convert the deionized water into the deionized water in a steam-water mixed state, the second preheater is used to heat the deionized water in the steam-water mixed state to increase the saturation of water vapor, the steam generator is used to evaporate and gasify the heated deionized water, and the steam superheater is used to heat the evaporated and gasified deionized water mixed with H2.

8. The solid oxide electrolysis cell hydrogen production system according to claim 1, characterized in that: The high-pressure protective gas cylinder is provided with a first pipeline and a second pipeline. The first pipeline is used to provide protective gas to the hydrogen production system. The first solenoid valve is installed on the second pipeline. When the hydrogen production system is running, the first solenoid valve is in a closed state. When the hydrogen production system stops running, the first solenoid valve is in an open state. After the pressure is reduced, the protective gas enters the steam superheater and the SOEC stack module in sequence to protect the electrode material of the SOEC stack module.

9. The solid oxide electrolysis cell hydrogen production system according to claim 1, characterized in that: The second solenoid valve is installed on the pipeline between the outlet pressure regulating valve of the compressed air bottle and the inlet of the air electric heater. When the hydrogen production system is running, the second solenoid valve is in a closed state. When the hydrogen production system stops running, the second solenoid valve is in an open state, and the compressed air enters the air electric heater after being depressurized to protect the air electric heater.

10. A method for operating a solid oxide electrolytic cell hydrogen production system, characterized in that: The solid oxide electrolysis cell hydrogen production system according to any one of claims 1 to 9 comprises the following steps: (1) keeping the first solenoid valve and the second solenoid valve of the system in a closed state, turning on the blower of the system, introducing protective gas into the system, adjusting the flow rate of the protective gas to a first target flow rate, adjusting the speed of the blower to a target speed, turning on the electric air heater of the system, and adjusting the air flow rate and outlet air temperature of the electric air heater; (2) when the outlet air temperature of the SOEC stack module of the system reaches 500° C., and the temperature of the water vapor superheater, the steam generator, and the pipe between the water vapor superheater, the steam generator and the SOEC stack module of the system reaches above 200° C., the deionized water pump of the system is turned on to supply deionized water and H2 to the system, and when the flow rates of the deionized water and the H2 reach a second target flow rate, the flow rate of the protective gas is reduced to 0; when the temperature of the SOEC stack module is in an increasing state, the flow rate of the deionized water is increased to maintain the flow rate ratio of H2 to water vapor at the inlet of the SOEC stack module greater than 1:20; (3) turning on the DC power supply connected to the SOEC stack module, setting the target voltage value and voltage rise rate, adjusting the flow rate of the deionized water and the H2 at the system inlet according to the electrolysis current, and adjusting the air flow rate and temperature at the SOEC stack module inlet; (4) When the current of the SOEC stack module reaches a first target value, the flow rate of the deionized water, the flow rate of the H2, and the flow rate of the air are maintained unchanged, and the electrolysis ratio of the water vapor is always maintained within a limit value set by the SOEC stack module during the electrolysis process; (5) when the electrolysis current is 0, reducing the flow rate of the deionized water at the system inlet to a second target value, and adjusting the air flow rate and outlet air temperature of the electric air heater; (6) When the outlet temperature of the SOEC stack module drops to 500° C., the protective gas is introduced into the system. When the flow rate of the protective gas reaches the third target value, the deionized water pump is turned off and the supply of H2 is stopped.

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