Ammonia fuel SOFC power generation system

Abstract

The invention relates to the technical field of power generation equipment, and particularly discloses an ammonia fuel SOFC power generation system, which comprises a fuel supply and treatment subsystem for providing ammonia fuel and preheating and cracking the ammonia fuel; the air supply subsystem is used for providing air and preheating the air; the combustion heat supply subsystem serves as a fuel combustion place and supplies heat to the fuel supply and treatment subsystem and the air supply subsystem; the SOFC electric pile subsystem is used as a place for generating electrochemical reaction; and the electric energy conversion subsystem is used for performing power supply type conversion and storage on the current generated in the SOFC pile subsystem. The fuel raw material used by the system is ammonia fuel, other methane auxiliary gas is not needed, ammonia water is not needed, the step of ammonia water vaporization is not needed, energy consumption is reduced, and the whole power generation system is simple in structure, high in power generation efficiency and high in raw material utilization rate.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation equipment, and in particular to an ammonia fuel SOFC power generation system. Background Art

[0002] Solid oxide fuel cells (SOFCs) are systems that generate electricity through electrochemical reactions. For example, a natural gas SOFC system reforms the fuel into hydrogen at high temperatures. The hydrogen is then ionized into hydrogen ions within the cell, which then combine with oxygen ions in the air at the cathode to form water, releasing electricity.

[0003] Traditional SOFC power generation systems use hydrogen produced by reforming alkanes or alcohols. However, these fuels are more expensive than ammonia, and their tail gas contains carbon dioxide, which contributes to the greenhouse effect. Ammonia-fueled SOFC power generation systems, on the other hand, emit nitrogen and water vapor, which are carbon dioxide-free and environmentally friendly. Consequently, ammonia-fueled SOFC power generation systems are gaining increasing attention from researchers.

[0004] For example, patent application CN113540541B discloses a SOFC fueled by ammonia, a cascade power generation system, and an operating method. The SOFC, fueled by ammonia, comprises an anode layer, an electrolyte layer, a separator layer, and a cathode layer. Compressed ammonia is fed into the anode. The ammonia concentration is preferably between 0.65 and 0.85, and the utilization rate of hydrogen generated by ammonia decomposition in the SOFC is 75%. However, this system requires a large bottoming cycle system consisting of an ammonia turbine and an ammonia separator, resulting in a complex system.

[0005] Patent application CN116470107A also discloses a high-efficiency ammonia-fueled solid oxide fuel cell power generation system. The system includes a pre-configured, connected porous media burner, a mixer, an ammonia heat exchanger, a first air heat exchanger, a second air heat exchanger, a blower, a solid oxide fuel cell (SOFC) stack, an afterburner, a reformer, a hydrogen separator, methane and ammonia gas cylinders, and multiple valves. However, this system still requires methane gas as an auxiliary, and does not truly implement a fully ammonia-fueled solid oxide fuel cell power generation system.

[0006] Ammonia cracking produces hydrogen (H2) by decomposing ammonia (NH3). This is an endothermic reaction that requires high temperatures and a catalyst, with the reaction temperature ranging from 750°C to 850°C. Heating methods for ammonia cracking include electrical heating or fuel combustion. Electrical heating requires additional electricity, reducing the overall efficiency of the SOFC power generation system. Fuel combustion also reduces the efficiency of the SOFC power generation system because the fuel directly burns and releases heat, rather than entering the stack to participate in the electrochemical reaction and discharge. Summary of the Invention

[0007] The purpose of the present invention is to develop a more energy-saving and efficient ammonia fuel SOFC power generation system to solve the problems in the prior art of being unable to generate electricity using pure ammonia fuel, having a complex power generation system, and having low power generation efficiency.

[0008] The present invention is implemented through the following technical solution: an ammonia fuel SOFC power generation system, comprising: A fuel supply and processing subsystem, used for providing ammonia fuel and preheating and cracking the ammonia fuel; An air supply subsystem, used for supplying and preheating air; The combustion and heating subsystem serves as the place where fuel is burned and provides heat to the fuel supply and processing subsystem and the air supply subsystem; The SOFC stack subsystem serves as the site where the electrochemical reaction occurs; and an electric energy conversion subsystem for converting and storing the current generated in the SOFC stack subsystem into a power source type; The gas inlet of the fuel supply and processing subsystem is connected to an ammonia supply pipeline, the gas outlet of the fuel supply and processing subsystem is connected to the anode feed port of the SOFC stack subsystem, the air inlet of the air supply subsystem is connected to an air supply pipeline, the air outlet of the air supply subsystem is connected to the cathode feed port of the SOFC stack subsystem, the inlet of the combustion and heating subsystem is connected to both the anode tail gas outlet and the cathode tail gas outlet of the SOFC stack subsystem, the outlet of the combustion and heating subsystem is connected to both the flue gas inlet of the fuel supply and processing subsystem and the flue gas inlet of the air supply subsystem, the flue gas outlet of the fuel supply and processing subsystem and the flue gas outlet of the fuel supply and processing subsystem are connected to the atmosphere, and the current outlet of the SOFC stack subsystem is connected to the current inlet of the power conversion subsystem.

[0009] Compared with the existing technology, the fuel raw material used in the entire process is ammonia fuel, and no other methane auxiliary gas is required. The ammonia fuel directly uses ammonia gas instead of ammonia water, and there is no need for the ammonia water vaporization step, which saves energy. The entire power generation system has a simple structure, high power generation efficiency, and high utilization rate of raw materials.

[0010] In one possible embodiment, the fuel supply and processing subsystem includes an ammonia heat exchanger and an ammonia cracker, the fuel side inlet of the ammonia heat exchanger is externally connected to an ammonia supply pipeline, the flue gas inlet of the ammonia heat exchanger is connected to the flue gas outlet of the air supply subsystem, the fuel side outlet of the ammonia heat exchanger is connected to the fuel gas inlet of the ammonia cracker, the fuel side outlet of the ammonia cracker is connected to the anode inlet of the SOFC stack subsystem, the flue gas inlet of the ammonia cracker is connected to the flue gas outlet of the combustion heating subsystem, the flue gas outlet of the ammonia cracker is connected to the flue gas inlet of the air supply subsystem, and the flue gas outlet of the ammonia heat exchanger is connected to the atmosphere.

[0011] In this solution, the ammonia heat exchanger preheats incoming ammonia, which is then cracked into hydrogen and nitrogen in the ammonia cracker. The hydrogen is then fed into the anode of the SOFC stack for an electrochemical reaction. The preheated ammonia flue gas is cooled and discharged into the atmosphere.

[0012] In a possible embodiment, the ammonia cracker is filled with an ammonia cracking hydrogen production catalyst.

[0013] In one possible embodiment, the ammonia cracker's gas inlet is also connected to an external hydrogen supply line. This hydrogen supply line serves as a heat source for system startup. Initially, the system requires heat to preheat the ammonia to crack it into hydrogen and nitrogen, thereby initiating the subsequent electrochemical reaction. The initial heat required by the system comes from the high-temperature flue gas generated by the combustion of this external hydrogen in the combustion heating subsystem.

[0014] In one possible embodiment, the air supply subsystem includes an air supply fan and an air preheater, the preheated air outlet of the air preheater is connected to the cathode inlet of the SOFC stack subsystem, the flue gas inlet of the air preheater is connected to the flue gas outlet of the ammonia cracker, the flue gas outlet of the air preheater is connected to the flue gas inlet of the ammonia heat exchanger, and the air supply fan is connected to an external air supply pipe.

[0015] In the above scheme, the air supply fan transmits outside air to the air preheater. The preheated air enters the cathode of the SOFC stack subsystem directly to participate in the electrochemical reaction. The flue gas outlet of the air preheater is connected to the flue gas inlet of the ammonia heat exchanger. This allows the flue gas heat generated by the system to be absorbed by the air preheater and then further absorbed by the ammonia heat exchanger. This allows for more efficient energy recycling in the system, simplifies the system, and improves efficiency.

[0016] In one possible embodiment, the ammonia heat exchanger preheats the ammonia fuel to 750-850° C. This temperature range is the optimal temperature range for cracking ammonia to produce hydrogen.

[0017] In one possible embodiment, the combustion heating subsystem includes a burner, the inlet of the burner is connected to both the anode tail gas outlet and the cathode tail gas outlet of the SOFC stack subsystem, and the outlet of the burner is connected to the flue gas inlet of the ammonia cracker.

[0018] In one possible embodiment, the combustion heating subsystem further includes an oxygen sensor, which is installed in the pipeline connecting the flue gas outlet of the burner and the flue gas inlet of the ammonia cracker. The oxygen sensor can monitor the oxygen content in the flue gas from the burner, and use this parameter to control the air flow rate supplied by the air blower to ensure normal system operation.

[0019] In a possible implementation, the electric energy conversion subsystem includes a converter and a battery, the current outlet of the SOFC stack subsystem is connected to the current inlet of the battery, and the current outlet of the battery is connected to the current inlet of the converter.

[0020] In one possible embodiment, the converter is a DC / DC converter or a DC / AC converter. The converter is used to convert direct current generated by the electrochemical reaction in the power conversion subsystem into alternating current suitable for subsequent use.

[0021] The beneficial effects of the present invention are: 1. The fuel used in the present invention is ammonia, which does not require hydrocarbon combustion-supporting gases such as methane. It is economical and efficient. The exhaust gas emitted is nitrogen and water vapor, which does not contain carbon dioxide. It is environmentally friendly and will not increase the greenhouse effect.

[0022] 2. During the reforming process of alkane or alcohol fuels to produce hydrogen, water vapor is required to participate in the reaction, that is, water needs to be added and vaporized; however, the ammonia cracking in the present invention does not require the participation of water vapor, and there is no process of water vaporization absorbing heat, so the system efficiency is higher.

[0023] 3. The anode tail gas in SOFC is discharged to the burner, and after combustion, it provides heat to the fuel supply and processing subsystem and the air supply subsystem. No additional fuel or electrical power is consumed, and the system has high heat utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural diagram of the ammonia fuel SOFC power generation system of the present invention.

[0025] In the figure, 1. Fuel supply and processing subsystem; 11. Ammonia heat exchanger; 12. Ammonia cracker; 2. Air supply subsystem; 21. Air supply fan; 22. Air preheater; 3. Combustion and heating subsystem; 31. Burner; 32. Oxygen sensor; 4. SOFC stack subsystem; 5. Power conversion subsystem; 51. Converter; 52. Battery. DETAILED DESCRIPTION

[0026] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only intended to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter ranges described in the present invention. Reasonable variations derived therefrom are still within the scope of protection of the claims of the present invention.

[0027] In the description of the embodiments of this application, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on the specific circumstances.

[0028] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] See also Figure 1 As shown, the present invention discloses an ammonia fuel SOFC power generation system, including: a fuel supply and processing subsystem 1, used to provide ammonia fuel and preheat and crack the ammonia fuel; an air supply subsystem 2, used to provide air and preheat the air; a combustion and heating subsystem 3, serving as a place for fuel combustion and supplying heat to the fuel supply and processing subsystem 1 and the air supply subsystem 2; a SOFC stack subsystem 4, serving as a place for electrochemical reactions; and an electric energy conversion subsystem 5, used to convert and store the current generated in the SOFC stack subsystem into a power type.

[0030] The fuel supply and processing subsystem 1 includes an ammonia heat exchanger 11 and an ammonia cracker 12. The fuel-side inlet of the ammonia heat exchanger 11 is connected to an external ammonia supply pipeline. The ammonia entering from the outside is preheated to 750-850°C in the ammonia heat exchanger 11 and then enters the ammonia cracker 12 for cracking. The fuel-side outlet of the ammonia heat exchanger 11 is connected to the gas inlet of the ammonia cracker 12. The ammonia cracker 12 is filled with an ammonia cracking hydrogen production catalyst, which can catalytically crack high-temperature ammonia at a temperature of 750-850°C into hydrogen and nitrogen. The ammonia cracking hydrogen production catalyst here can be any catalyst on the market that can catalyze the cracking of ammonia into hydrogen and nitrogen, preferably a solid ammonia cracking hydrogen production catalyst. The fuel-side outlet of the ammonia cracker 12 is connected to the anode inlet of the SOFC stack subsystem 4, that is, the hydrogen obtained by cracking directly enters the anode of the SOFC stack subsystem for electron-loss oxidation electrochemical reaction.

[0031] The gas inlet pipeline of the ammonia cracker 12 is also connected to a hydrogen supply pipeline. This hydrogen supply pipeline is used to supply the starting fuel for the heat source to start the system from scratch. At the beginning of the system operation, the hydrogen directly supplied from the outside is introduced into the combustion and heating subsystem 3 and ignited and burned. The heat generated after combustion is used to preheat the ammonia and air, providing a high-temperature environment for the ammonia cracker 12. Then the ammonia fuel is cracked and the subsequent electrochemical reaction produces tail gas as a recycling process for the next combustion of the combustion and heating subsystem 3.

[0032] The air supply subsystem 2 includes an air supply blower 21 and an air preheater 22. The preheated air outlet of the air preheater 21 is connected to the cathode inlet of the SOFC stack subsystem 4. The air supply blower 21 is connected to an external air supply pipeline. The air supply blower 21 compresses and pumps outside air into the system's air preheater 22. The air is heated to the required temperature in the air preheater 22 before entering the cathode of the SOFC stack subsystem 4 to undergo electron reduction. The flue gas inlet of the air preheater 22 is connected to the flue gas outlet of the ammonia cracker 12, which is in turn connected to the flue gas inlet of the ammonia heat exchanger 11. The flue gas outlet of the air preheater 22 is connected to the flue gas inlet of the ammonia heat exchanger 11, which is then connected to the atmosphere. The flue gas heat generated by the system's combustion is absorbed by the air preheater 22 and can be further absorbed by the ammonia heat exchanger, resulting in more efficient energy recycling and system simplification while achieving greater energy utilization. The flue gas produced by combustion is actually nitrogen and water vapor. After heat exchange, it becomes nitrogen and water and can be directly discharged into the atmosphere.

[0033] The combustion and heating subsystem 3 includes a burner 31, the inlet of which is connected to both the anode tail gas outlet and the cathode tail gas outlet of the SOFC stack subsystem 4, and the outlet of the burner 31 is connected to the flue gas inlet of the ammonia cracker 12. The combustion reaction occurring in the system burner 31 is the combustion of a mixed gas consisting of hydrogen from the anode tail gas and oxygen from the cathode tail gas of the SOFC stack subsystem 4. The high-temperature flue gas generated after combustion first enters the ammonia cracker 12 to provide a high-temperature environment for ammonia cracking. The flue gas then enters the air preheater 22 and the ammonia preheater 11 to preheat the air and ammonia. The combustion and heating subsystem 3 also includes an oxygen sensor 32, which is arranged on a pipeline connecting the outlet of the burner 31 and the flue gas inlet of the ammonia cracker 12. The oxygen sensor 32 can monitor the oxygen content in the flue gas from the burner 31, and judge whether the hydrogen in the anode tail gas is completely burned based on this, and further control the flow rate of air to be supplied by the air blower 21 to ensure the normal operation of the system and achieve automatic adaptation to complete combustion.

[0034] In the SOFC stack subsystem 4, the simultaneous electrochemical reactions at the anode and cathode generate direct current (DC). This DC power is directly fed into the power conversion subsystem 5 for conversion or storage. The power conversion subsystem 5 comprises a DC / DC / AC converter 51 and a battery 52. ​​The current outlet of the SOFC stack subsystem 4 is connected to the battery 52, which in turn is connected to the current inlet of the DC / DC / AC converter 51. This converter ultimately converts the DC power into AC power suitable for grid connection.

[0035] In summary, the working principle of the present invention is: by burning the hydrogen and oxygen coming out of the anode tail gas outlet and the cathode tail gas outlet of the SOFC stack subsystem 4 in the combustion and heating subsystem 3, the high-temperature flue gas after combustion enters the fuel supply and treatment subsystem 3 and the air supply subsystem 2, and preheats the ammonia and air brought in from the outside, so that the high-temperature ammonia enters the fuel supply and treatment subsystem 1 and is cracked (the high-temperature flue gas also provides a high-temperature environment in the ammonia cracker 12), the cracked gas enters the SOFC stack subsystem 4 to undergo a chemical reaction to generate direct current, and the tail gas generated by the chemical reaction of the SOFC stack subsystem 4 enters the combustion and heating subsystem 3 again for combustion to realize circulating heating, and finally the cold flue gas after preheating the ammonia and air is directly connected to the atmosphere from the flue gas outlet of the fuel supply and treatment subsystem 1 and discharged, thereby realizing sustainable operation of the entire system.

[0036] In the description of the embodiments of the present application, it should be noted that in the description of the present application, terms such as "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present application.

[0037] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. An ammonia fuel SOFC power generation system, characterized in that: include: A fuel supply and processing subsystem (1), for providing ammonia fuel and preheating and cracking the ammonia fuel; An air supply subsystem (2), used for supplying air and preheating the air; The combustion and heating subsystem (3) serves as a place for fuel combustion and provides heat to the fuel supply and processing subsystem and the air supply subsystem; The SOFC stack subsystem (4) serves as a place where electrochemical reactions occur; and an electric energy conversion subsystem (5), for converting and storing the electric current generated in the SOFC stack subsystem into a power source type; The gas inlet of the fuel supply and treatment subsystem (1) is connected to an ammonia supply pipeline, the gas outlet of the fuel supply and treatment subsystem (1) is connected to the anode feed port of the SOFC stack subsystem (4), the air inlet of the air supply subsystem (2) is connected to the air supply pipeline, the air outlet of the air supply subsystem (2) is connected to the cathode feed port of the SOFC stack subsystem (4), the inlet of the combustion and heating subsystem (3) is connected to both the anode tail gas outlet and the cathode tail gas outlet of the SOFC stack subsystem (4), the outlet of the combustion and heating subsystem (3) is connected to both the flue gas inlet of the fuel supply and treatment subsystem (1) and the flue gas inlet of the air supply subsystem (2), the flue gas outlet of the fuel supply and treatment subsystem (1) and the flue gas outlet of the fuel supply and treatment subsystem (1) are connected to the atmosphere, and the current outlet of the SOFC stack subsystem (4) is connected to the current inlet of the electric energy conversion subsystem (5).

2. The ammonia fuel SOFC power generation system according to claim 1, characterized in that: The fuel supply and processing subsystem (1) comprises an ammonia heat exchanger (11) and an ammonia cracker (12); the fuel side inlet of the ammonia heat exchanger (11) is externally connected to an ammonia supply pipeline; the flue gas inlet of the ammonia heat exchanger (11) is connected to the flue gas outlet of the air supply subsystem (2); the fuel side outlet of the ammonia heat exchanger (11) is connected to the fuel gas inlet of the ammonia cracker (12); the fuel side outlet of the ammonia cracker (12) is connected to the anode inlet of the SOFC stack subsystem (4); the flue gas inlet of the ammonia cracker (12) is connected to the outlet of the combustion heating subsystem (3); the flue gas outlet of the ammonia cracker (12) is connected to the flue gas inlet of the air supply subsystem (2); and the flue gas outlet of the ammonia heat exchanger (11) is connected to the atmosphere.

3. The ammonia fuel SOFC power generation system according to claim 2, characterized in that: The ammonia cracker (12) is filled with an ammonia cracking hydrogen production catalyst.

4. The ammonia fuel SOFC power generation system according to claim 2, characterized in that: The fuel gas inlet pipeline of the ammonia cracker (12) is also externally connected to a hydrogen supply pipeline.

5. The ammonia fuel SOFC power generation system according to claim 2, characterized in that: The air supply subsystem (2) comprises an air supply fan (21) and an air preheater (22); the air outlet of the air preheater (22) is connected to the cathode inlet of the SOFC stack subsystem (4); the flue gas inlet of the air preheater (22) is connected to the flue gas outlet of the ammonia cracker (12); the flue gas outlet of the air preheater (22) is connected to the flue gas inlet of the ammonia heat exchanger (11); and the air supply fan (21) is externally connected to an air supply pipeline.

6. The ammonia fuel SOFC power generation system according to claim 5, characterized in that: The ammonia heat exchanger (11) preheats the ammonia fuel to 750-850°C.

7. The ammonia fuel SOFC power generation system according to claim 1, characterized in that: The combustion heating subsystem (3) comprises a burner (31), the inlet of the burner (31) being connected to both the anode tail gas outlet and the cathode tail gas outlet of the SOFC stack subsystem (4), and the outlet of the burner (31) being connected to the flue gas inlet of the ammonia cracker (12).

8. The ammonia fuel SOFC power generation system according to claim 7, characterized in that: The combustion heating subsystem (3) further comprises an oxygen sensor (32), wherein the oxygen sensor (32) is arranged on a pipeline connecting the outlet of the burner (31) and the flue gas inlet of the ammonia cracker (12).

9. The ammonia fuel SOFC power generation system according to claim 1, characterized in that: The electric energy conversion subsystem (5) comprises a converter (51) and a battery (52); the current outlet of the SOFC stack subsystem (4) is connected to the current inlet of the battery (52); and the current outlet of the battery (52) is connected to the current inlet of the converter (51).

10. The ammonia fuel SOFC power generation system according to claim 9, characterized in that: The converter (51) is a DC / DC converter or a DC / AC converter.

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