Reversible solid oxide fuel cell-electrolytic cell system and operation method thereof

Abstract

The invention relates to a reversible solid oxide fuel cell-electrolytic cell (rSOC for short) system and an operation method of the reversible solid oxide fuel cell-electrolytic cell (rSOC for short) system, and particularly relates to a reversible solid oxide fuel cell-electrolytic cell (rSOC for short) system and an operation method of the reversible solid oxide fuel cell-electrolytic cell (rSOC for short) system. The system mainly comprises an rSOC stack module, a fuel preheater, a reformer, a desulfurizer, a heat exchange type steam generator, a deionized water pump, an air preheater, a fan, a combustor, a circulating fan, a stop valve, a heat tracing band, a power supply, a control system, a pipeline, a heat insulation material, a sensor and the like. According to the system, an rSOC stack module fuel tail gas circulation process is adopted, free switching of the system between an SOFC mode and an SOEC mode is achieved by adjusting switches of stop valves at different positions on a pipeline, all parts in the system are fully utilized, the process framework of the rSOC system is simplified to the maximum extent, gradient utilization of energy is achieved in the SOFC mode and the SOEC mode, and the system is suitable for large-scale popularization and application. The system energy consumption is reduced; the system is simple in structure, stable, reliable, low in energy consumption and high in operability.

Description

Technical Field

[0001] The present invention relates to the technical field of solid oxide fuel cells, and in particular to a reversible solid oxide fuel cell-electrolyzer system and an operation method thereof. Background Art

[0002] Reversible Solid Oxide Fuel Cell and Electrolysis Cell (rSOC) technology combines the power generation function of a solid oxide fuel cell (SOFC) and the electrolysis hydrogen production function of a solid oxide electrolysis cell (SOEC) in one system.

[0003] As a highly efficient energy conversion device, SOFC can convert fuel into electrical energy. The system power generation efficiency can reach more than 60%. It is the most efficient power generation technology among all power generation equipment, and has low pollutant emissions. It is a clean, low-carbon, safe and efficient power generation method. It is considered to be a new energy power generation technology with the broadest development and application prospects in the future, and many researchers have devoted themselves to it.

[0004] The SOEC electrolysis hydrogen production system, under an applied voltage and high temperature, electrolyzes water vapor to produce high-purity hydrogen and oxygen, realizing the conversion of electrical energy and thermal energy into chemical energy; 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 efficiency and the largest current density. SOEC is currently the most efficient water electrolysis technology; on the other hand, SOEC electrolysis hydrogen production technology has a wide adaptability to raw materials. The feed of the SOEC electrolyzer is water vapor. If carbon dioxide is added, syngas (a mixture of hydrogen and carbon monoxide) can be generated, and then synthetic fuels (e-fuels, such as diesel and aviation fuel) can be further produced; therefore, SOEC technology is expected to be widely used in carbon dioxide recovery, fuel production and chemical synthesis products, with the advantage of carbon neutral cycle.

[0005] The operating modes of SOFC and SOEC technologies are both reversible. If SOEC water electrolysis hydrogen production and SOFC power generation are combined into a system, a highly efficient hydrogen or electricity chemical energy storage device can be formed; when there is excess electricity, the surplus electricity of renewable energy can be used to produce hydrogen, and the electrical energy can be efficiently converted into chemical energy (hydrogen energy). When electricity is tight, the stored hydrogen can be used to generate electricity and obtain electrical energy through electrochemical reactions.

[0006] The SOFC power generation system and the SOEC electrolysis hydrogen production system can use the same high-temperature solid oxide fuel cell stack. The systems also include air preheaters, fuel preheaters, heat exchange steam generators, etc. How to organically combine the two, make full use of each component in different modes, minimize the complexity of the system, and realize the cascade utilization of energy is one of the important directions of the development of rSOC technology.

[0007] Therefore, developing a rSOC system with simple system architecture, stability and reliability, low energy consumption and strong operability plays an important role in the development of the rSOC system. Summary of the invention

[0008] In order to solve the technical problems of the conventional reversible solid oxide fuel cell-electrolyzer system being complex, the mode switching process being complex, the energy consumption being high, and the reliability being low, the present invention provides the following technical solutions:

[0009] The first object of the present invention is to provide a reversible solid oxide fuel cell-electrolyzer system, including an rSOC stack module, a fuel preheater, a reformer, a desulfurizer, a heat exchange steam generator, a deionized water pump, an air preheater, a fan, a burner, a circulating fan, a stop valve, a heating belt, a power supply, a control system, pipelines, insulation materials, sensors, etc.

[0010] Before the system is started, the system can be switched between the SOFC mode and the SOEC mode by adjusting the corresponding stop valve.

[0011] The reformer uses a precious metal catalyst and is used for catalytic reforming reaction of natural gas and water vapor in SOFC mode, and acts as a mixer of water vapor, hydrogen and fuel-side circulating tail gas in SOEC mode.

[0012] In the catalytic burner, in the SOFC mode, part of the fuel exhaust gas at the outlet of the rSOC stack module is mixed with high-temperature air and burned in the burner, and the generated high-temperature flue gas is used to heat the fuel preheater, the air preheater, and the heat exchange steam generator; in the SOEC mode, the burner uses external natural gas as fuel and the high-temperature air at the outlet of the rSOC stack module as a combustion aid, and the generated high-temperature flue gas is used to heat the air preheater.

[0013] In the SOFC mode, a part of the fuel exhaust gas at the outlet of the rSOC stack module is mixed with fresh natural gas under the action of the circulating fan and enters the reformer for catalytic reaction, and then enters the fuel preheater and the rSOC stack module to generate electricity; in the SOEC mode, a part of the high-temperature hydrogen containing water vapor at the outlet of the rSOC stack module is mixed with fresh water vapor under the action of the circulating fan and enters the reformer, fuel preheater and rSOC stack module in sequence.

[0014] The heat exchange steam generator, in the SOFC mode, when the system is not generating electricity, exchanges heat between the high-temperature flue gas generated by the burner and deionized water to generate water vapor. When the system reaches the rated power generation state, the system does not need to supply deionized water from the outside and the heat exchange steam generator does not generate steam. In the SOEC mode, the heat exchange steam generator exchanges heat between the high-temperature exhaust gas at the fuel side outlet of the rSOC stack module and deionized water to generate fresh water vapor, thereby realizing heat recovery of the fuel exhaust gas.

[0015] The second object of the present invention is to provide an operation method of a reversible solid oxide fuel cell-electrolyzer system, characterized in that: ① In SOFC mode, before the system is started, the shut-off valve between the fuel outlet of the rSOC stack module and the burner is opened, the shut-off valve between the burner and the fuel preheater is opened, the shut-off valve between the heat exchange steam generator and the waste heat recovery is opened, the shut-off valve from the heat exchange steam generator to the reformer is opened, the shut-off valve between the fuel outlet of the rSOC stack module and the fuel preheater is closed, the shut-off valve from the outlet of the heat exchange steam generator to the product hydrogen is closed, and the shut-off valve on the inlet natural gas pipeline of the burner is closed, and natural gas, air, and deionized water are supplied to the system, and the circulating fan is The speed gradually reaches the target value, and the system heats up and increases the power generation at a certain rate; when the system enters the rated power generation state in SOFC mode, the shut-off valve from the heat exchange steam generator to the reformer is closed and opened. The system does not need to provide deionized water from the outside to produce fresh water vapor. The system only needs to supply natural gas and air. A part of the fuel exhaust gas at the outlet of the rSOC stack module and the high-temperature air at the outlet of the rSOC stack module enter the burner for mixed combustion. The high-temperature flue gas generated heats the fuel preheater and the air preheater. Another part of the fuel exhaust gas at the outlet of the rSOC stack module is mixed with fresh natural gas under the action of the circulating fan and enters the reformer for catalytic reaction, and finally enters the rSOC stack. Modules participate in power generation; ② In SOEC mode, before the system is started, open the shut-off valve between the fuel outlet of the rSOC stack module and the fuel preheater, open the shut-off valve from the outlet of the heat exchange steam generator to the product hydrogen, open the shut-off valve from the heat exchange steam generator to the reformer, open the shut-off valve on the inlet natural gas pipeline of the burner, close the shut-off valve between the fuel outlet of the rSOC stack module and the burner, close the shut-off valve between the burner and the fuel preheater, close the shut-off valve between the heat exchange steam generator and the waste heat recovery, close the circulating fan, and supply hydrogen, deionized water, air and natural gas for combustion for startup. The system heats up at a certain rate and increases the load of electrolytic hydrogen production; system When the rated electrolysis hydrogen production state is entered in the SOEC mode, the circulating fan is turned on to the target speed, and the system does not need to be supplied with hydrogen from the outside. The system only needs to supply deionized water, air and natural gas for the burner. A part of the fuel exhaust gas at the outlet of the rSOC stack module is mixed with fresh water vapor under the action of the circulating fan and re-enters the rSOC stack module. Another part of the fuel exhaust gas at the outlet of the rSOC stack module successively enters the fuel preheater and the heat exchange steam generator to achieve the cascade utilization of heat, and finally condenses and separates liquid water to obtain product hydrogen; the external natural gas enters the burner and is mixed with the high-temperature air at the outlet of the rSOC stack module to burn, and the high-temperature flue gas generated is used to heat the fresh air.

[0016] Compared with the prior art, the advantages of the present invention are: a reversible solid oxide fuel cell-electrolyzer system, ① different from the conventional rSOC system, the system adopts the rSOC stack module fuel tail gas circulation process and the stop valve set at a special position on the pipeline, realizing the organic combination and free switching of the SOFC power generation mode and the SOEC electrolysis hydrogen production mode; ② the system adopts the rSOC stack module fuel tail gas circulation process, and realizes the free switching of the system between the SOFC mode and the SOEC mode by adjusting the switch of the stop valve at different positions on the pipeline; ③ the various components in the system are fully utilized, and the process architecture of the rSOC system is simplified to the maximum extent; ④ the cascade utilization of energy is realized in both the SOFC mode and the SOEC mode, reducing the energy consumption of the system; ⑤ the system architecture is simple, stable and reliable, low in energy consumption, and strong in operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 is a schematic diagram of this system;

[0019] Among them: 1. rSOC stack module; 2. Fuel preheater; 3. Reformer; 4. Desulfurizer; 5. Heat exchange steam generator; 6. Deionized water pump; 7. Air preheater; 8. Fan; 9. Burner; 10. Circulating fan; 11-17. Stop valve; 18. Heating belt; 19. Power supply; 20. Control system; 21. Pipeline; 22. Insulation material; 23. Sensor, etc. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0021] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings:

[0022] like Figure 1As shown, the first object of the present invention is to provide a reversible solid oxide fuel cell-electrolyzer system, including an rSOC stack module 1, a fuel preheater 2, a reformer 3, a desulfurizer 4, a heat exchange steam generator 5, a deionized water pump 6, an air preheater 7, a fan 8, a burner 9, a circulating fan 10, a stop valve 11-17, a heating belt 18, a power supply 19, a control system 20, a pipeline 21, a thermal insulation material 22, a temperature sensor 23, etc.

[0023] Before the system is started, the system can be switched between the SOFC mode and the SOEC mode by adjusting the corresponding stop valves 11-17.

[0024] The reformer 3 uses a precious metal catalyst and is used for catalytic reforming reaction of natural gas and water vapor in SOFC mode, and acts as a mixer of water vapor, hydrogen, and fuel-side circulating tail gas in SOEC mode.

[0025] In the catalytic burner 9, in the SOFC mode, part of the fuel exhaust gas at the outlet of the rSOC stack module 1 is mixed with high-temperature air and burned in the burner 9, and the generated high-temperature flue gas is used to heat the fuel preheater 2, the air preheater 7, and the heat exchange steam generator 5; in the SOEC mode, the burner 9 uses external natural gas as fuel and the high-temperature air at the outlet of the rSOC stack module 1 as a combustion aid, and the generated high-temperature flue gas is used to heat the air preheater 7.

[0026] In the SOFC mode, a part of the fuel exhaust gas at the outlet of the rSOC stack module 1 is mixed with fresh natural gas under the action of the circulating fan 10 and enters the reformer 3 for catalytic reaction, and then enters the fuel preheater 2 and the rSOC stack module 1 to generate electricity; in the SOEC mode, a part of the high-temperature hydrogen containing water vapor at the outlet of the rSOC stack module 1 is mixed with fresh water vapor under the action of the circulating fan 10 and enters the reformer 3, the fuel preheater 2, and the rSOC stack module 1 in sequence.

[0027] The heat exchange steam generator 5, in the SOFC mode, when the system is not generating electricity, exchanges heat between the high-temperature flue gas generated by the burner 9 and deionized water to generate water vapor. When the system reaches the rated power generation state, the system does not need to supply deionized water from the outside and the heat exchange steam generator 5 does not generate steam. In the SOEC mode, the heat exchange steam generator 5 exchanges heat between the high-temperature exhaust gas at the fuel side outlet of the rSOC stack module 1 and deionized water to generate fresh water vapor, thereby realizing heat recovery of the fuel exhaust gas.

[0028] The second object of the present invention is to provide an operation method of a reversible solid oxide fuel cell-electrolyzer system, characterized in that: ① In SOFC mode, before the system is started, the shut-off valve 11 between the fuel outlet of the rSOC stack module 1 and the burner 9 is opened, the shut-off valve 13 between the burner 9 and the fuel preheater 2 is opened, the shut-off valve 14 between the heat exchange steam generator 5 and the waste heat recovery is opened, the shut-off valve 17 from the heat exchange steam generator 5 to the reformer 3 is opened, the shut-off valve 12 between the fuel outlet of the rSOC stack module 1 and the fuel preheater 2 is closed, the shut-off valve 15 from the outlet of the heat exchange steam generator 5 to the product hydrogen is closed, and the shut-off valve 16 on the inlet natural gas pipeline of the burner 9 is closed, and the system supply Natural gas, air and deionized water are introduced, and the speed of the circulating fan 10 gradually reaches the target value. The system heats up and increases the power generation at a certain rate. When the system enters the rated power generation state in the SOFC mode, the stop valve 17 from the heat exchange steam generator 5 to the reformer 3 is closed. The system does not need to provide deionized water from the outside to generate fresh water vapor. The system only needs to supply natural gas and air. A part of the fuel exhaust gas at the outlet of the rSOC stack module 1 and the high-temperature air at the outlet of the rSOC stack module 1 enter the burner 9 for mixed combustion. The high-temperature flue gas generated heats the fuel preheater 2 and the air preheater 7. Another part of the fuel exhaust gas at the outlet of the rSOC stack module 1 is mixed with the fresh natural gas under the action of the circulating fan 10. ② In SOEC mode, before the system is started, open the stop valve 12 between the fuel outlet of the rSOC stack module 1 and the fuel preheater 2, open the stop valve 15 from the outlet of the heat exchange steam generator 5 to the product hydrogen, open the stop valve 17 from the heat exchange steam generator 5 to the reformer 3, open the stop valve 16 on the inlet natural gas pipeline of the burner 9, close the stop valve 11 between the fuel outlet of the rSOC stack module 1 and the burner 9, close the stop valve 13 between the burner 9 and the fuel preheater 2, close the stop valve 14 between the heat exchange steam generator 5 and the waste heat recovery, close the circulation fan 10, and the system is started. The system is heated and the load of hydrogen production by electrolysis is increased at a certain rate by using hydrogen, deionized water, air and natural gas for combustion; when the system enters the rated hydrogen production state by electrolysis in SOEC mode, the circulating fan 10 is turned on to the target speed, and the system does not need to provide hydrogen from the outside. The system only needs to supply deionized water, air and natural gas for burner 9. A part of the fuel tail gas at the outlet of the rSOC stack module 1 is mixed with fresh water vapor under the action of the circulating fan 10 and re-enters the rSOC stack module 1. Another part of the fuel tail gas at the outlet of the rSOC stack module 1 successively enters the fuel preheater 2 and the heat exchange steam generator 5, so as to realize the step-by-step utilization of heat, and finally condenses and separates the liquid water to obtain the product hydrogen;The external natural gas enters the burner 9 and is mixed with the high-temperature air at the outlet of the rSOC stack module 1 to burn, and the high-temperature flue gas generated is used to heat the fresh air. ;

[0029] Compared with the prior art, the advantages of the present invention are: a reversible solid oxide fuel cell-electrolyzer system, ① different from the conventional rSOC system, the system adopts the rSOC stack module 1 fuel exhaust gas circulation process and the stop valves 11-17 set at special positions on the pipeline, realizing the organic combination and free switching of the SOFC power generation mode and the SOEC electrolysis hydrogen production mode; ② the system adopts the rSOC stack module 1 fuel exhaust gas circulation process, and realizes the free switching of the system between the SOFC mode and the SOEC mode by adjusting the switches of the stop valves 11-17 at different positions on the pipeline 21; ③ the various components in the system are fully utilized, and the process architecture of the rSOC system is simplified to the maximum extent; ④ the cascade utilization of energy is realized in both the SOFC mode and the SOEC mode, reducing the energy consumption of the system; ⑤ the system architecture is simple, stable and reliable, low in energy consumption, and strong in operability.

[0030] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A reversible solid oxide fuel cell-electrolyzer system, including an rSOC stack module, a fuel preheater, a reformer, a desulfurizer, a heat exchange steam generator, a deionized water pump, an air preheater, a fan, a burner, a circulating fan, a stop valve, a heating belt, a power supply, a control system, pipelines, insulation materials, sensors, etc.

2. The reversible solid oxide fuel cell-electrolyzer system according to claim 1, characterized in that: Before the system is started, the system can be switched between the SOFC mode and the SOEC mode by adjusting the corresponding stop valve.

3. The reversible solid oxide fuel cell-electrolyzer system according to claim 1, characterized in that: The reformer uses a precious metal catalyst and is used for catalytic reforming reaction of natural gas and water vapor in SOFC mode, and acts as a mixer of water vapor, hydrogen and fuel-side circulating tail gas in SOEC mode.

4. The reversible solid oxide fuel cell-electrolyzer system according to claim 1, characterized in that: In the catalytic burner, in the SOFC mode, part of the fuel exhaust gas at the outlet of the rSOC stack module is mixed with high-temperature air and burned in the burner, and the generated high-temperature flue gas is used to heat the fuel preheater, the air preheater, and the heat exchange steam generator; in the SOEC mode, the burner uses external natural gas as fuel and the high-temperature air at the outlet of the rSOC stack module as a combustion aid, and the generated high-temperature flue gas is used to heat the air preheater.

5. The reversible solid oxide fuel cell-electrolyzer system according to claim 1, characterized in that: In the SOFC mode, a part of the fuel exhaust gas at the outlet of the rSOC stack module is mixed with fresh natural gas under the action of the circulating fan and enters the reformer for catalytic reaction, and then enters the fuel preheater and the rSOC stack module to generate electricity; in the SOEC mode, a part of the high-temperature hydrogen containing water vapor at the outlet of the rSOC stack module is mixed with fresh water vapor under the action of the circulating fan and enters the reformer, fuel preheater and rSOC stack module in sequence.

6. The reversible solid oxide fuel cell-electrolyzer system according to claim 1, characterized in that: The heat exchange steam generator, in the SOFC mode, when the system is not generating electricity, exchanges heat between the high-temperature flue gas generated by the burner and deionized water to generate water vapor. When the system reaches the rated power generation state, the system does not need to supply deionized water from the outside and the heat exchange steam generator does not generate steam. In the SOEC mode, the heat exchange steam generator exchanges heat between the high-temperature exhaust gas at the fuel side outlet of the rSOC stack module and deionized water to generate fresh water vapor, thereby realizing heat recovery of the fuel exhaust gas.

7. The method for operating a reversible solid oxide fuel cell-electrolyzer system according to any one of claims 1 to 6, characterized in that: ① In SOFC mode, before the system is started, open the stop valve between the fuel outlet of the rSOC stack module and the burner, open the stop valve between the burner and the fuel preheater, open the stop valve between the heat exchange steam generator and the waste heat recovery, open the stop valve from the heat exchange steam generator to the reformer, close the stop valve between the fuel outlet of the rSOC stack module and the fuel preheater, close the stop valve from the outlet of the heat exchange steam generator to the product hydrogen, close the stop valve on the inlet natural gas pipeline of the burner, supply natural gas, air, and deionized water to the system, the speed of the circulating fan gradually reaches the target value, and the system heats up and increases the power generation at a certain rate; When the system enters the rated power generation state in SOFC mode, the shut-off valve from the heat exchange steam generator to the reformer is closed and opened. The system does not need to provide deionized water from the outside to generate fresh steam. The system only needs to supply natural gas and air. A part of the fuel exhaust gas at the outlet of the rSOC stack module and the high-temperature air at the outlet of the rSOC stack module enter the burner for mixed combustion. The high-temperature flue gas generated heats the fuel preheater and the air preheater. Another part of the fuel exhaust gas at the outlet of the rSOC stack module is mixed with fresh natural gas under the action of the circulating fan and enters the reformer for catalytic reaction, and finally enters the rSOC stack module to participate in power generation; ② In SOEC mode, before the system is started, Open the shut-off valve between the fuel outlet of the rSOC stack module and the fuel preheater, open the shut-off valve from the outlet of the heat exchange steam generator to the product hydrogen, open the shut-off valve from the heat exchange steam generator to the reformer, open the shut-off valve on the inlet natural gas pipeline of the burner, close the shut-off valve between the fuel outlet of the rSOC stack module and the burner, close the shut-off valve between the burner and the fuel preheater, close the shut-off valve between the heat exchange steam generator and the waste heat recovery, close the circulating fan, supply hydrogen, deionized water, air and natural gas for combustion for startup, and the system heats up at a certain rate and increases the load of electrolytic hydrogen production; the system enters the SOEC mode When in the rated electrolytic hydrogen production state, the circulating fan is turned on to the target speed, and the system does not need to be supplied with hydrogen from the outside. The system only needs to be supplied with deionized water, air and natural gas for the burner. A part of the fuel exhaust gas at the outlet of the rSOC stack module is mixed with fresh water vapor under the action of the circulating fan and re-enters the rSOC stack module. Another part of the fuel exhaust gas at the outlet of the rSOC stack module successively enters the fuel preheater and the heat exchange steam generator to achieve the cascade utilization of heat, and finally condenses and separates liquid water to obtain product hydrogen; the external natural gas enters the burner and is mixed with the high-temperature air at the outlet of the rSOC stack module for combustion, and the high-temperature flue gas generated is used to heat fresh air.

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