Indirect ammonia fuel solid oxide fuel cell system
By combining electric and self-heating ammonia decomposition reactors, the problems of high parasitic energy consumption, slow preheating start and nitrogen oxide emissions of indirect ammonia fuel solid oxide fuel cell systems are solved, and rapid preheating and high-efficiency utilization are achieved , improves electrical and thermal efficiency.
Patent Information
- Application Number
- CN202411400274.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-09
- Publication Date
- 2025-01-10
AI Technical Summary
Indirect ammonia fuel solid oxide fuel cell systems have problems such as high parasitic energy consumption, slow preheating start and nitrogen oxide emissions.
Combining the electric-thermal ammonia decomposition reactor and the self-thermal ammonia decomposition reactor, after preliminary heating through the electric-thermal reactor, the self-thermal reactor uses the catalytic channel and the combustion channel to achieve rapid preheating, and decompose it through the two reactors. Ammonia fuel reduces dependence on electric heating, uses the high-temperature waste heat of combustion exhaust to exchange heat, and reduces nitrogen oxide emissions.
It realizes rapid preheating and starting, reduces parasitic electrical power consumption, improves electrical efficiency and thermal efficiency, and avoids environmental pollution of nitrogen oxides.
Smart Images
Figure CN119297349A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of power generation equipment, in particular to an indirect ammonia fuel solid oxide fuel cell system. Background Art
[0002] The operating temperature of solid oxide fuel cells (SOFC) is usually between 600 and 1000°C, so it can adapt to a variety of fuels, such as hydrogen, methane, methanol, natural gas, synthesizers, and ammonia. When ammonia is used as a fuel, no carbon emissions are generated and no precious metal catalysis is required. In addition, ammonia fuel itself is easy to store, has high energy density, and good safety. Therefore, ammonia has broad prospects as a fuel for SOFC.
[0003] However, the technology of using ammonia fuel as a fuel for SOFC stacks is not yet mature, which may lead to problems such as poisoning of anode catalysts, degradation of battery performance and pollutant emissions. The general treatment method is to decompose ammonia fuel into 75% hydrogen and 25% nitrogen under the catalysis of nickel or ruthenium-based porous catalysts, and then directly supply it to the SOFC stack for power generation, so it is called indirect ammonia fuel SOFC. The ammonia decomposition reaction is an endothermic reaction. The required heat can come from an electric heating device, but it will lead to higher parasitic energy consumption, and in many application scenarios, there is no external power supply condition; the required heat can also come from the high-temperature exhaust gas generated by combustion, but this process not only has the problem of difficult ammonia combustion and slow startup process, but also the problem of generating a large amount of nitrogen oxides and forming pollution due to combustion. To solve this problem, some people have proposed to use external hydrogen supply to burn and generate heat, but the storage and use costs of external hydrogen supply are high.
[0004] Therefore, the problems of indirect ammonia fuel SOFC, such as high parasitic energy consumption, slow preheating and startup, and nitrogen oxide emissions, need to be urgently solved. Summary of the invention
[0005] In order to solve the deficiencies in the prior art, the present invention provides an indirect ammonia fuel solid oxide fuel cell system, which combines an electric thermal ammonia decomposition reactor with a natural ammonia decomposition reactor, and can effectively solve the problems of high parasitic energy consumption, slow preheating and start-up, and nitrogen oxide emissions during the use of the existing system.
[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:
[0007] An indirect ammonia fuel solid oxide fuel cell system, comprising:
[0008] An ammonia decomposition reaction unit, the ammonia decomposition reaction unit comprises an electric ammonia decomposition reactor and an autothermal ammonia decomposition reactor, a combustion channel and a catalytic channel are arranged inside the autothermal ammonia decomposition reactor; the input end of the electric ammonia decomposition reactor is connected to an ammonia gas cylinder, and the output end of the electric ammonia decomposition reactor is connected to a mixer and the combustion channel of the autothermal ammonia decomposition reactor in sequence; the inlet of the catalytic channel in the autothermal ammonia decomposition reactor is connected to the ammonia gas cylinder, and the outlet of the catalytic channel in the autothermal ammonia decomposition reactor is connected to the anode inlet of the stack;
[0009] The cathode inlet of the stack is connected to the air supply unit, and the anode outlet and cathode outlet of the stack are connected to the mixer and the inlet of the combustion channel in the ammonia decomposition reactor in sequence.
[0010] Furthermore, the output end of the electrothermal ammonia decomposition reactor is equipped with a hydrogen storage tank to store the mixed gas generated by the electrothermal ammonia decomposition reactor.
[0011] Furthermore, the outlet of the combustion channel in the ammonia decomposition reactor is connected to a heat exchange unit, and the heat exchange unit includes a first heat exchanger and a second heat exchanger. The first heat exchanger is arranged between the ammonia gas cylinder and the catalytic channel in the autothermal ammonia decomposition reactor; the second heat exchanger is arranged on the air supply unit, and the first heat exchanger and the second heat exchanger are connected to the outlet of the combustion channel in the ammonia decomposition reactor in sequence, and the combustion exhaust gas is sequentially exchanged with the ammonia gas input into the catalytic channel in the autothermal ammonia decomposition reactor and the air input into the cathode of the fuel cell stack.
[0012] Furthermore, the first heat exchanger and the second heat exchanger are both shell-and-tube heat exchangers.
[0013] Furthermore, the air supply unit includes a fan, and the fan is connected to the cathode of the input fuel cell stack through an air supply channel.
[0014] Furthermore, a booster pump is provided between the mixer and the combustion channel of the autothermal ammonia decomposition reactor.
[0015] Furthermore, a catalytic layer is arranged in the catalytic channel of the autothermal ammonia decomposition reactor, and the catalytic layer material is a nickel-based catalyst.
[0016] Furthermore, the anode outlet and cathode outlet of the fuel cell stack are both connected to a buffer gas storage tank, and the buffer gas storage tank is connected to a mixer.
[0017] Furthermore, the inlet of the catalytic channel in the ammonia decomposition reactor and the inlet of the electric thermal ammonia decomposition reactor can be connected to the ammonia cylinder through a three-way valve.
[0018] Furthermore, the current output end of the battery stack is connected to a converter, which is a DC-AC converter.
[0019] Beneficial effects:
[0020] (1) The present invention provides an indirect ammonia fuel solid oxide fuel cell system, which adopts a structure in which an electric thermal ammonia decomposition reactor and a self-heating ammonia decomposition reactor are connected in parallel; compared with the prior art, while achieving rapid preheating and startup of the system, it avoids excessive reliance on electric heating during power generation, reduces parasitic power consumption, and improves electrical efficiency.
[0021] (2) The ammonia fuel is decomposed by two types of ammonia decomposition reactors, so that the mixed gas entering the ammonia decomposition reactor for combustion is mainly hydrogen, thereby avoiding the pollution of the environment by the production of nitrogen oxides.
[0022] (3) The system is also equipped with two heat exchangers, which fully utilize the high-temperature waste heat in the combustion exhaust gas as the heat source for fuel gas, air and the system, thereby improving the overall heat utilization efficiency.
[0023] (4) The system of the present invention is designed with fast preheating start-up, low parasitic energy consumption, high electrical efficiency and high thermal efficiency, and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is a structural schematic diagram of an embodiment of an indirect ammonia fuel solid oxide fuel cell system of the present invention;
[0025] Among them: 1-ammonia gas cylinder; 2-three-way valve; 31-first heat exchanger; 32-second heat exchanger; 4-electric thermal ammonia decomposition reactor; 5-hydrogen storage tank; 6-self-heating ammonia decomposition reactor; 7-boosting pump; 8-mixer; 91-first valve; 92-second valve; 10-cell stack; 11-buffer gas storage tank; 12-blower; 13-DC-AC converter. DETAILED DESCRIPTION
[0026] In the description of this patent, it should be noted that, unless otherwise clearly specified and limited, the terms "connected", "connected", and "set" should be understood in a broad sense, for example, it can be fixedly connected or set, or detachably connected or set, or integrally connected or set. For ordinary technicians in this field, the specific meanings of the above terms in this patent can be understood according to specific circumstances.
[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.
[0028] See attached Figure 1The present invention provides an indirect ammonia fuel solid oxide fuel cell system, including an ammonia decomposition reaction unit, a heat exchange unit, an ammonia gas cylinder 1, a hydrogen storage tank 5, a mixer 8, and a fuel cell stack 10.
[0029] The ammonia gas cylinder 1 is used to store ammonia gas. The ammonia gas cylinder 1 is connected to the ammonia decomposition reaction unit through a pipeline to provide ammonia gas to the ammonia decomposition reaction unit.
[0030] The ammonia decomposition reaction unit includes an electric ammonia decomposition reactor 4 and an autothermal ammonia decomposition reactor 6, and a combustion channel and a catalytic channel are arranged inside the autothermal ammonia decomposition reactor 6; more specifically, the input end of the electric ammonia decomposition reactor 4 is connected to the ammonia gas cylinder 1, and the output end of the electric ammonia decomposition reactor 4 is connected to the hydrogen storage tank 5, the mixer 8, and the combustion channel of the autothermal ammonia decomposition reactor 6 in sequence, that is, the ammonia fuel is first catalytically decomposed by the electric ammonia decomposition reactor 4, and hydrogen fuel is provided to the autothermal ammonia decomposition reactor 6 as a combustion component, so that the autothermal ammonia decomposition reactor 6 is rapidly heated to reach the target temperature.
[0031] The inlet of the catalytic channel in the autothermal ammonia decomposition reactor 6 is connected to the ammonia gas cylinder 1, and the outlet is connected to the anode inlet of the fuel cell stack 10 for catalytic decomposition of the ammonia fuel. The catalytic channel in the autothermal ammonia decomposition reactor 6 is used to catalytically decompose the input ammonia fuel and input it into the anode of the fuel cell stack 10.
[0032] The cathode inlet of the fuel cell stack 10 is connected to the air supply unit, and the anode outlet and cathode outlet of the fuel cell stack 10 are both connected to the inlet of the combustion channel in the ammonia decomposition reactor 6 .
[0033] In this embodiment, the outlet of the combustion channel in the ammonia decomposition reactor 6 is connected to a heat exchange unit, and the heat exchange unit includes a first heat exchanger 31 and a second heat exchanger 32. The first heat exchanger 31 is arranged between the ammonia gas cylinder 1 and the catalytic channel in the self-heating ammonia decomposition reactor 6; the second heat exchanger 32 is arranged on the air supply unit, and the first heat exchanger 31 and the second heat exchanger 32 are connected to the outlet of the combustion channel in the ammonia decomposition reactor 6 in sequence, and the combustion exhaust gas is used as a high-temperature medium to exchange heat with the ammonia input into the catalytic channel in the self-heating ammonia decomposition reactor 6 and the air input into the cathode of the fuel cell stack 10 in sequence, thereby making full use of the high-temperature waste heat in the combustion exhaust gas and improving the overall heat utilization efficiency.
[0034] In this embodiment, the air supply unit includes a fan 12, and the fan 12 is connected to the cathode of the input fuel cell stack 10 through an air supply channel.
[0035] In this embodiment, the inlet of the catalytic channel in the ammonia decomposition reactor 6 and the inlet of the electric thermal ammonia decomposition reactor 4 can be connected to the ammonia gas cylinder 1 through the three-way valve 2 to improve the compactness of the gas supply end structure.
[0036] In this embodiment, the indirect ammonia fuel solid oxide fuel cell system also includes a boost pump 7, which is connected between the mixer 8 and the combustion channel of the autothermal ammonia decomposition reactor 6; the boost pump is used to increase the pressure of the combustion gas and promote the combustion reaction.
[0037] In this embodiment, the indirect ammonia fuel solid oxide fuel cell system also includes a first valve 91 and a second valve 92 for controlling the gas flow rate. The first valve 91 connects the hydrogen storage tank 5 and the mixer 8, and the second valve 92 connects the mixer 8 and the buffer gas storage tank 11.
[0038] In this embodiment, the current output end of the battery stack 10 is connected to the converter 13, and the converter 13 is a DC-AC converter that can convert direct current into alternating current that can be used by users.
[0039] In this embodiment, the first heat exchanger 31 and the second heat exchanger 32 are both shell-and-tube heat exchangers, which are used to heat the fuel and air respectively by the high-temperature combustion exhaust gas to realize waste heat recovery and utilization.
[0040] In this embodiment, a catalytic layer is arranged in the catalytic channel of the autothermal ammonia decomposition reactor 6, and the catalytic layer material is a nickel-based catalyst.
[0041] In the present invention, the function of the hydrogen storage tank 5 is to store the mixed gas generated by the electrothermal ammonia decomposition reactor 4 for preheating the autothermal ammonia decomposition reactor 6 during the startup process.
[0042] In the present invention, in this embodiment, the anode outlet and the cathode outlet of the stack 10 are both connected to the buffer gas storage tank 11, and the buffer gas storage tank 11 is connected to the mixer 8. The function of the buffer gas storage tank 11 is to store the tail gas of the stack and provide sufficient fuel for the combustion reaction of the autothermal ammonia decomposition reactor 6 during operation.
[0043] The working process of the above-mentioned indirect ammonia fuel solid oxide fuel cell system is as follows:
[0044] 1. Preheating stage: first heat the electric ammonia decomposition reactor 4 to the target operating temperature of 450°C to 600°C, then switch the three-way valve 2 to provide a small amount of ammonia fuel to the electric ammonia decomposition reactor 4. At this time, an ammonia decomposition reaction occurs in the electric ammonia decomposition reactor 4 until the storage volume of the decomposed gas in the hydrogen storage tank 5 reaches 1 / 3 of the rated capacity. Then, start the fan, open valves 91 and 92, and start the booster pump 7. The mixed gas enters the autothermal ammonia decomposition reactor 6 at a certain pressure to cause a combustion reaction, so that the autothermal ammonia decomposition reactor 6 is rapidly heated to the target temperature of 450°C to 600°C.
[0045] 2. Transition stage: When the autothermal ammonia decomposition reactor 6 reaches the target operating temperature, the three-way valve 2 is switched to allow the ammonia fuel to flow into the autothermal ammonia decomposition reactor 6; at this time, the valve 91 is closed to allow the decomposed gas of the electrothermal ammonia decomposition reactor 4 to fill the hydrogen storage tank 5, and then the three-way valve 2 is switched to stop supplying fuel to the electrothermal ammonia decomposition reactor 4 and stop electric heating; at this time, the decomposed gas in the hydrogen storage tank 5 can be used for the next preheating process; then, the ammonia fuel flow rate is gradually increased to maximize the hydrogen production, and the valve 92 is adjusted to control the combustion reaction in the autothermal ammonia decomposition reactor 6 to control the temperature of the entire system at about 600°C.
[0046] 3. Start-up phase: When the temperature of the fuel cell stack 10 is stabilized at 600° C., the fuel cell stack 10 is started, and the hydrogen-oxygen electrochemical reaction is used to output current to achieve stable operation of the system.
[0047] 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 aforementioned embodiments, it should be understood by those skilled in the art that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. An indirect ammonia fuel solid oxide fuel cell system, characterized in that: include: An ammonia decomposition reaction unit, the ammonia decomposition reaction unit comprising an electric ammonia decomposition reactor (4) and an autothermal ammonia decomposition reactor (6), wherein a combustion channel and a catalytic channel are arranged inside the autothermal ammonia decomposition reactor (6); the input end of the electric ammonia decomposition reactor (4) is connected to an ammonia gas cylinder (1), and the output end of the electric ammonia decomposition reactor (4) is connected to a mixer (8) and the combustion channel of the autothermal ammonia decomposition reactor (6) in sequence; the inlet of the catalytic channel in the autothermal ammonia decomposition reactor (6) is connected to the ammonia gas cylinder (1), and the outlet of the catalytic channel in the autothermal ammonia decomposition reactor (6) is connected to the anode inlet of the fuel cell stack (10); The cathode inlet of the fuel cell stack (10) is connected to the air supply unit, and the anode outlet and cathode outlet of the fuel cell stack (10) are connected in sequence to the mixer (8) and the inlet of the combustion channel in the ammonia decomposition reactor (6).
2. The indirect ammonia fuel solid oxide fuel cell system according to claim 1, characterized in that: The output end of the electrothermal ammonia decomposition reactor (4) is equipped with a hydrogen storage tank (5) for storing the mixed gas generated by the electrothermal ammonia decomposition reactor (4).
3. The indirect ammonia fuel solid oxide fuel cell system according to claim 1, characterized in that: The outlet of the combustion channel in the ammonia decomposition reactor (6) is connected to a heat exchange unit, the heat exchange unit comprising a first heat exchanger (31) and a second heat exchanger (32), the first heat exchanger (31) being arranged between the ammonia gas cylinder (1) and the catalytic channel in the autothermal ammonia decomposition reactor (6); the second heat exchanger (32) being arranged on the air supply unit, the first heat exchanger (31) and the second heat exchanger (32) being connected to the outlet of the combustion channel in the ammonia decomposition reactor (6) in sequence, and exchanging heat between the combustion exhaust gas and the ammonia gas input into the catalytic channel in the autothermal ammonia decomposition reactor (6) and the air input into the cathode of the fuel cell stack (10) in sequence.
4. The indirect ammonia fuel solid oxide fuel cell system according to claim 3, characterized in that: The first heat exchanger (31) and the second heat exchanger (32) are both shell-and-tube heat exchangers.
5. The indirect ammonia fuel solid oxide fuel cell system according to claim 1, characterized in that: The air supply unit comprises a fan (12), and the fan (12) is connected to the cathode of the input cell stack (10) through an air supply channel.
6. The indirect ammonia fuel solid oxide fuel cell system according to claim 1, characterized in that: A booster pump (7) is provided between the mixer (8) and the combustion channel of the autothermal ammonia decomposition reactor (6).
7. The indirect ammonia fuel solid oxide fuel cell system according to claim 1, characterized in that: A catalytic layer is arranged in the catalytic channel of the autothermal ammonia decomposition reactor (6), and the catalytic layer material is a nickel-based catalyst.
8. The indirect ammonia fuel solid oxide fuel cell system according to claim 1, characterized in that: The anode outlet and cathode outlet of the battery stack (10) are both connected to a buffer gas storage tank (11), and the buffer gas storage tank (11) is connected to a mixer (8).
9. The indirect ammonia fuel solid oxide fuel cell system according to claim 1, characterized in that: The inlet of the catalytic channel in the ammonia decomposition reactor (6) and the inlet of the electric heating ammonia decomposition reactor (4) can be connected to the ammonia gas cylinder (1) through a three-way valve (2).
10. The indirect ammonia fuel solid oxide fuel cell system according to claim 1, characterized in that: The current output end of the battery stack (10) is connected to a converter (13), and the converter (13) is a DC-AC converter.