An efficient power generation system and control method for an ammonia fuel solid oxide fuel cell

Abstract

The present invention discloses an efficient power generation system for an ammonia fuel solid oxide fuel cell. The efficient power generation system for the ammonia fuel solid oxide fuel cell includes a porous medium combustor, 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, a supplementary combustor, a reformer, a hydrogen separator, a methane gas cylinder, an ammonia gas cylinder, and multiple valves connected in a preset manner. In addition, the present invention also discloses a control method for the efficient power generation system of the ammonia fuel solid oxide fuel cell. The efficient power generation system for the ammonia fuel solid oxide fuel cell disclosed by the present invention is scientifically designed. In order to utilize ammonia efficiently, safely, and reliably, after ammonia is reformed externally to produce hydrogen, it then enters the fuel cell for power generation, and by using the method of methane rich combustion assistance, it plays a good role in the rapid response of the power generation system and the temperature balance of components, having great practical significance.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation equipment, and particularly to an efficient power generation system and control method for an ammonia-fueled solid oxide fuel cell. Background Art

[0002] A fuel cell is a power generation device that directly converts chemical energy into electrical energy through an electrochemical reaction of a fuel. It can not only improve the utilization efficiency of the fuel but also reduce the pollutants generated during fuel utilization. Therefore, it has advantages such as cleanness, high efficiency, safety, and convenience.

[0003] Currently, fuel cells are classified by electrolyte and include proton exchange membrane fuel cells, molten carbonate fuel cells, alkaline fuel cells, phosphoric acid fuel cells, and solid oxide fuel cells (SOFCs). Among them, solid oxide fuel cells belong to high-temperature fuel cells, have strong fuel adaptability, use non-precious metal catalysts, low costs, and high energy efficiency. Especially in occasions such as stationary power generation and combined heat and power supply, solid oxide fuel cells have broad application scenarios.

[0004] Ammonia is a zero-carbon fuel, and its use as a fuel can reduce carbon emissions. Due to advantages such as convenient storage, high energy density, and good safety, ammonia has great utilization prospects as a fuel for solid oxide fuel cell SOFCs.

[0005] Currently, the use of ammonia in a solid oxide fuel cell SOFC system has also encountered some problems, such as low fuel utilization rate, catalyst poisoning, battery performance degradation, and pollutant emissions. At present, the research on ammonia-fueled SOFCs is still insufficient, and scientific researchers are needed to solve the problems that occur.

[0006] Among them, when ammonia fuel is used in a fuel cell and a combined power generation system of a fuel cell - internal combustion engine / gas turbine, during the startup process of the system, the heat required for the decomposition process of ammonia often comes from the heat carried in the exhaust gas generated by combustion. This process not only has problems such as difficult ammonia combustion and slow startup process but also has problems of generating a large amount of nitrogen oxides and forming pollution due to combustion. It should be noted that during the startup process of the system, ammonia burns in the burner to release heat, and the obtained high-temperature flue gas heats the high-temperature components of the system. During this process, the combustion conditions of ammonia are harsh, a large amount of nitrogen oxides will be generated during the combustion process, and the startup process is quite slow.

[0007] In addition, an electric heater is also used to heat the system components. After the temperature reaches the working condition, ammonia is then introduced to carry out the power generation process of the fuel cell. However, an additional battery needs to be configured for power supply, which is not feasible when the power is limited or the cost is high.

[0008] Therefore, there is an urgent need to develop a technology that can solve the above technical problems. Summary of the Invention

[0009] The object of the present invention is to provide an efficient power generation system and control method for an ammonia fuel solid oxide fuel cell in view of the technical defects existing in the prior art.

[0010] To this end, the present invention provides an efficient power generation system for an ammonia fuel solid oxide fuel cell, including a porous medium burner, a mixer, an ammonia heat exchanger, a first air heat exchanger, a second air heat exchanger, a fan, a solid oxide fuel cell (SOFC) stack, a supplementary combustor, a reformer, a methane gas cylinder, and an ammonia gas cylinder, wherein:

[0011] The outlet of the ammonia gas cylinder is connected to one end of the second flow control valve;

[0012] The other end of the second flow control valve is respectively connected to one end of the first valve and the second valve;

[0013] The other end of the first valve is connected to the fuel cold flow inlet of the ammonia heat exchanger;

[0014] The fuel hot flow outlet of the ammonia heat exchanger is connected to the fuel inlet of the reformer through a three-way valve;

[0015] The other end of the second valve is connected to the ammonia gas inlet of the mixer;

[0016] The outlet of the methane gas cylinder is connected to one end of the third flow control valve;

[0017] The other end of the third flow control valve is connected to the gas inlet of the porous medium burner;

[0018] The gas outlet of the porous medium burner is connected to the methane gas inlet of the mixer;

[0019] The mixed gas outlet of the mixer is connected to the fuel inlet of the reformer through a three-way valve;

[0020] The fuel outlet of the reformer is respectively connected to one end of the fourth valve and the third valve;

[0021] The other end of the fourth valve is connected to the anode fuel inlet of the solid oxide fuel cell (SOFC) stack;

[0022] The other end of the third valve is connected to the fuel gas inlet of the supplementary combustor;

[0023] The air inlet of the fan is connected to the external atmospheric environment;

[0024] The air outlet of the fan is connected to the inlet of the first flow control valve;

[0025] The outlet of the first flow control valve is communicated with the air inlet of the first air heat exchanger;

[0026] The air outlet of the first air heat exchanger is communicated with the air inlet of the second air heat exchanger;

[0027] The air outlet of the second air heat exchanger is communicated with the cathode air inlet of the solid oxide fuel cell (SOFC) stack;

[0028] The anode exhaust gas outlet of the solid oxide fuel cell (SOFC) stack is communicated with the fuel gas inlet of the afterburner;

[0029] The cathode exhaust gas outlet of the solid oxide fuel cell (SOFC) stack is respectively communicated with the high-temperature waste gas inlet of the second air heat exchanger and the air inlet of the afterburner;

[0030] The outlet of the afterburner is communicated with the high-temperature waste gas inlet of the reformer;

[0031] The waste gas outlet of the reformer is communicated with the waste gas inlet of the ammonia heat exchanger;

[0032] The waste gas outlet of the ammonia heat exchanger is communicated with the air inlet of a hydrogen separator;

[0033] The hydrogen separator is used to recover the residual hydrogen in the system exhaust gas output by the ammonia heat exchanger.

[0034] After the waste gas outlets of the hydrogen separator and the second air heat exchanger converge and intersect, they are communicated with the waste gas inlet of the first air heat exchanger;

[0035] The hydrogen outlet of the hydrogen separator is respectively communicated with one ends of a fourth valve and a third valve;

[0036] The waste gas outlet of the first air heat exchanger is communicated with the external atmospheric environment.

[0037] In addition, the present invention also provides a control method for an efficient power generation system of an ammonia fuel solid oxide fuel cell as described above, which includes the following working modes:

[0038] I. In the start-up stage of the solid oxide fuel cell (SOFC) power generation system, first, open the third flow control valve for regulating methane, the sixth valve, the second flow control valve for regulating ammonia, the seventh valve, and the second valve. Methane undergoes rich combustion autothermal reforming with air in the porous medium burner to obtain a methane reforming mixed gas mainly composed of H2 and CO;

[0039] Then, the methane reforming mixed gas output by the porous medium burner and the ammonia passing through the second valve enter the mixer for uniform mixing, and then enter the reformer for catalytic reforming to obtain a high-temperature hydrogen-rich mixed gas. This step can gradually reduce the temperature gradient in the reformer, alleviate carbon deposition of methane during the catalytic reforming process, and increase the hydrogen content in the methane reforming mixed gas;

[0040] Then, the high-temperature hydrogen-rich mixed gas and the air inhaled by the blower respectively enter from the anode fuel inlet and the cathode air inlet of the solid oxide fuel cell (SOFC) stack, thereby increasing the temperature of the SOFC stack;

[0041] Next, after the fuel and air come out of the SOFC stack, a part of the air and fuel enter the afterburner and then burn in the afterburner. The high-temperature exhaust gas at the outlet of the afterburner further heats the equipment and gases in the reformer, the second air heat exchanger, the ammonia heat exchanger, and the first air heat exchanger through convective heat transfer; Another part of the air coming out of the stack is used to heat the second air heat exchanger and converges with other exhaust gases at the inlet of the first air preheater tail gas, and finally heats the SOFC power generation system to the normal operating condition.

[0042] In addition, the present invention also provides another control method for the high-efficiency power generation system of the ammonia fuel solid oxide fuel cell as described above, which includes the following working modes:

[0043] First, during the startup stage of the combined power generation system of the solid oxide fuel cell and the internal combustion engine, the generator set of the internal combustion engine starts to work first. Ammonia burns and does work in the internal combustion engine, and the internal combustion engine drives the generator installed thereon to output electric energy. At this time, the high-temperature exhaust gas output by the internal combustion engine is used to heat the ammonia heat exchanger and the first air heat exchanger.

[0044] Meanwhile, the porous medium burner in the system obtains a high-temperature fuel mixed gas through methane rich combustion autothermal reforming and catalytic reforming. The high-temperature fuel gas is heated after entering the SOFC stack. At this time, since the SOFC stack has not yet operated normally, the air and fuel at the outlet of the SOFC stack enter the afterburner for combustion, and the obtained high-temperature gas heats the reformer, the ammonia heat exchanger, the first air heat exchanger, and the second air heat exchanger.

[0045] As can be seen from the technical solutions provided by the present invention above, compared with the prior art, the present invention provides an efficient power generation system and control method for an ammonia fuel solid oxide fuel cell, which is scientifically designed. In order to efficiently, safely and reliably utilize ammonia, after ammonia is externally reformed to produce hydrogen (that is, methane is used for rich combustion autothermal reforming in a porous medium burner 11, and then mixed with ammonia for catalytic reforming to obtain hydrogen), it enters the fuel cell for power generation, and an optimized control method assisted by methane rich combustion plays a good role in the rapid response and component temperature balance of the power generation system, which has great practical significance.

[0046] The efficient power generation system for an ammonia fuel solid oxide fuel cell provided by the present invention is a power generation system with the characteristics of rapid response, low pollution and high performance, and has a wide market application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 FIG. 9 is a schematic structural diagram of Embodiment 1 of the efficient power generation system for an ammonia fuel solid oxide fuel cell provided by the present invention. At this time, the system is a solid oxide fuel cell power generation system with external ammonia reforming.

[0048] Figure 2 FIG. 13 is a schematic structural diagram of Embodiment 2 of the efficient power generation system for an ammonia fuel solid oxide fuel cell provided by the present invention. At this time, the system is a combined power generation system of a solid oxide fuel cell with external ammonia reforming and an internal combustion engine. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0050] In the description of this patent, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "set" should be understood in a broad sense. For example, it can be fixedly connected and set, or detachably connected and set, or integrally connected and set. For those of ordinary skill in the art, the specific meanings of the above terms in this patent can be understood according to specific situations.

[0051] In addition, the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0052] See Figure 1 , the present invention provides an efficient power generation system for an ammonia fuel solid oxide fuel cell, comprising a porous medium burner 11, a mixer 9, an ammonia heat exchanger 4, a first air heat exchanger 31, a second air heat exchanger 32, a blower 1, a solid oxide fuel cell (SOFC) stack 7, a supplementary combustor 10, a reformer 6, a methane gas cylinder 13 and an ammonia gas cylinder 12, wherein:

[0053] The gas outlet of the ammonia gas cylinder 12 is communicated with one end of a second flow control valve 22;

[0054] The other end of the second flow control valve 22 is respectively communicated with one end of a first valve 51 and a second valve 52;

[0055] The other end of the first valve 51 is communicated with the fuel cold flow inlet of the ammonia heat exchanger 4;

[0056] The fuel hot flow outlet of the ammonia heat exchanger 4 is communicated with the fuel inlet of the reformer 6 through a three-way valve 14;

[0057] The other end of the second valve 52 is communicated with the ammonia gas inlet of the mixer 9;

[0058] The gas outlet of the methane gas cylinder 13 is communicated with one end of a third flow control valve 23;

[0059] The other end of the third flow control valve 23 is communicated with the gas inlet of the porous medium burner 11;

[0060] The gas outlet of the porous medium burner 11 is communicated with the methane gas inlet of the mixer 9;

[0061] The mixed gas outlet of the mixer 9 is communicated with the fuel inlet of the reformer 6 through a three-way valve 14;

[0062] It should be noted that for the present invention, the outlet of the ammonia gas cylinder is divided into two branches by the second flow control valve 22. The first branch is connected to the ammonia gas inlet of the mixer 9 through the second flow control valve 22 and the second valve 52, and the second branch is connected to the fuel cold flow inlet of the ammonia heat exchanger 4 through the second flow control valve 22 and the first valve 51.

[0063] The fuel outlet of the reformer 6 is respectively connected to one end of the fourth valve 54 and the third valve 53;

[0064] The other end of the fourth valve 54 is connected to the anode fuel inlet of the solid oxide fuel cell (SOFC) stack 7;

[0065] The other end of the third valve 53 is connected to the fuel gas inlet of the afterburner 10;

[0066] It should be noted that for the present invention, the fuel outlet of the reformer 6 is divided into two branches. The first branch is connected to the anode fuel inlet of the solid oxide fuel cell (SOFC) stack 7 through the fourth valve 54, and the second branch is connected to the fuel gas inlet of the afterburner 10 through the third valve 53.

[0067] The air inlet of the blower 1 is connected to the external atmospheric environment, and the blower 1 is used to suck in external air;

[0068] The air outlet of the blower 1 is connected to the inlet of the first flow control valve 21;

[0069] The outlet of the first flow control valve 21 is connected to the air inlet of the first air heat exchanger 31;

[0070] The air outlet of the first air heat exchanger 31 is connected to the air inlet of the second air heat exchanger 32;

[0071] The air outlet of the second air heat exchanger 32 is connected to the cathode air inlet of the solid oxide fuel cell (SOFC) stack 7;

[0072] The anode exhaust gas outlet of the solid oxide fuel cell (SOFC) stack 7 is connected to the fuel gas inlet of the afterburner 10;

[0073] The cathode exhaust gas outlet of the solid oxide fuel cell (SOFC) stack 7 is respectively connected to the high-temperature exhaust gas inlet of the second air heat exchanger 32 and the air inlet of the afterburner 10;

[0074] The outlet of the afterburner 10 is connected to the high-temperature exhaust gas inlet of the reformer 6;

[0075] The exhaust gas outlet of the reformer 6 is connected to the exhaust gas inlet of the ammonia heat exchanger 4;

[0076] The exhaust gas outlet of the ammonia heat exchanger 4 is connected to the inlet of a hydrogen separator 15;

[0077] The hydrogen separator 15 is used to recover the residual hydrogen in the system exhaust gas output by the ammonia heat exchanger 4.

[0078] The exhaust gas outlet of the hydrogen separator 15 and the exhaust gas outlet of the second air heat exchanger 32 are connected to the exhaust gas inlet of the first air heat exchanger 31 after converging and intersecting;

[0079] The hydrogen outlet of the hydrogen separator 15 is respectively connected to one ends of a fourth valve 54 and a third valve 53;

[0080] The exhaust gas outlet of the first air heat exchanger 31 is connected to the external atmospheric environment.

[0081] In the present invention, specifically, on the connecting pipelines between the ammonia gas cylinder 12 and the second flow control valve 22 and between the methane gas cylinder 13 and the third flow control valve 23, a sixth valve 56 and a seventh valve 57 are respectively arranged.

[0082] In the present invention, specifically, the cathode exhaust gas outlet of the solid oxide fuel cell (SOFC) stack 7 is connected to the air inlet of the afterburner 10 through a fifth valve 55.

[0083] In the present invention, specifically, the current output end of the solid oxide fuel cell (SOFC) stack 7 is connected to the first inverter 8;

[0084] The first inverter 8 is used to receive the low-voltage direct current output by the solid oxide fuel cell (SOFC) stack 7 and then convert and output alternating current.

[0085] It should be noted that for the present invention, the high-temperature exhaust gas at the anode outlet of the solid oxide fuel cell (SOFC) stack 7 is connected to the fuel gas inlet of the afterburner 10, and the high-temperature exhaust gas at the cathode outlet is divided into two branches. The first branch is connected to the air inlet of the afterburner 10 through the fifth valve 55, and the second branch is connected to the high-temperature exhaust gas inlet of the second air heat exchanger 32. The outlet of the afterburner 10 is connected to the high-temperature exhaust gas inlet of the reformer 6, the exhaust gas outlet of the reformer 6 is connected to the exhaust gas inlet of the ammonia heat exchanger 4, the exhaust gas outlet of the second air heat exchanger 32 and the waste heat outlet of the ammonia heat exchanger 4 are connected to the exhaust gas inlet of the first air heat exchanger 31 after converging and intersecting, and finally, the exhaust gas outlet of the first air heat exchanger 31 leads to the atmosphere.

[0086] In the present invention, for the power generation system provided by the present invention, it is a solid oxide fuel cell power generation system with external reforming of ammonia fuel. The porous medium burner 11 therein performs premixed rich combustion of methane and air. The porous medium is divided into two layers, namely a premixed layer and a reaction layer. Between the two layers of porous medium is an ignition combustion layer. In the premixed layer, methane and air are uniformly and fully mixed, ignited in the combustion layer to achieve rich combustion of methane, and then the high-temperature mixed gas further realizes the autothermal reforming reaction of the gas in the reaction layer to obtain more carbon monoxide CO and hydrogen H2.

[0087] In the present invention, for the mixer 9, the methane-rich high-temperature gas mixture and the normal-temperature ammonia gas are uniformly mixed inside the mixer 9, so that the temperature of the ammonia gas is increased to the catalytic reforming temperature, and the methane-rich high-temperature gas mixture is also reduced to a suitable catalytic reforming range. The mixer 9 needs to meet the indexes of the pressure drop, concentration uniformity, and temperature uniformity of the mixed gas.

[0088] In the present invention, the reformer 6 is of a shell-and-tube structure, with the fuel gas mixture flowing inside the tubes and the high-temperature waste gas flowing outside the tubes to heat the catalyst inside the tubes. Among them, the porous medium balls of Ni-Al2O3 are filled inside the tubes.

[0089] In the present invention, the function of the afterburner 10 is to burn the unburned gas output by the solid oxide fuel cell (SOFC) stack 7, release the chemical energy of the fuel and convert it into heat energy, and the generated high-temperature waste gas is used to heat the reformer 6 and the air and fuel in the ammonia heat exchanger 4. Under low load conditions, in order to ensure that the waste gas has sufficient heat to maintain the heating conditions in the reformer 6 and the ammonia heat exchanger 4, a part of hydrogen needs to be introduced through the afterburner fuel branch after the reformer 6 to provide the required gas heat.

[0090] In the present invention, the fan 1 (i.e., the air compressor) is used to supply the outside air to the oxygen electrode in the solid oxide fuel cell (SOFC) stack 7 and maintain it under specific pressure conditions to ensure the pressure balance between the cathode and anode in the stack.

[0091] In the present invention, for the two fuel gas branches after the reformer 6, the opening and closing of the branch valves (including the fourth valve 54 and the third valve 53) can be adjusted according to the operating conditions.

[0092] For example: when the system is started, since the temperature in the solid oxide fuel cell (SOFC) stack 7 is at normal temperature and there is a large gap from the reaction temperature of about 800 °C, when the temperature of the stack has not reached the ideal reaction temperature, the fuel conversion efficiency in the stack is low. At this time, a large amount of combustible gas will flow out of the stack and enter the afterburner 10. Therefore, in this process, it is not necessary to open the third valve 53 of the afterburner branch, and the heat loss of the high-temperature gas can also be reduced, and more can be used for heating the solid oxide fuel cell (SOFC) stack 7.

[0093] In the variable operating condition and power reduction stage, the reduction of the high-temperature waste gas volume in the solid oxide fuel cell (SOFC) stack 7 results in a reduction of the heat for maintaining the reaction temperature of components such as the system heat exchanger and the reformer 6. At this time, it is necessary to open the fuel branch of the afterburner 10 to supplement the insufficient heat in the system and ensure that the system temperature is around the ideal reaction temperature.

[0094] In the present invention, in terms of specific implementation, refer to Figure 2As shown, the high-efficiency power generation system of the ammonia fuel solid oxide fuel cell (SOFC) provided by the present invention, which is a solid oxide fuel cell power generation system for external reforming of ammonia fuel, can also be combined with an internal combustion engine to form a SOFC-ICE combined power generation system, that is, a combined power generation system of a solid oxide fuel cell (SOFC) for external reforming of ammonia fuel and an internal combustion engine (ICE).

[0095] That is, the high-efficiency power generation system of the ammonia fuel solid oxide fuel cell is also connected to the internal combustion engine 16 to form a combined power generation system of a solid oxide fuel cell and an internal combustion engine. The specific structure is as follows:

[0096] The fuel outlet of the reformer 6 is also communicated with the fuel inlet of the internal combustion engine 16.

[0097] The gas outlet of the ammonia gas cylinder 12 is also communicated with the air inlet of the fuel pump of the internal combustion engine 16.

[0098] It should be noted that for the present invention, for the SOFC-ICE combined system using ammonia fuel, a branch will be added after the reformer 6, that is, it will be divided into three branches. The first branch is connected to the anode of the solid oxide fuel cell (SOFC) stack 7, the second branch is connected to the fuel gas inlet of the afterburner 10, and the third branch is connected to the fuel inlet of the generator set of the internal combustion engine 16, and there will be an independent ammonia gas cylinder to directly supply fuel for the internal combustion engine.

[0099] Specifically, the exhaust gas outlet of the internal combustion engine 16 is communicated with the exhaust gas inlet of the ammonia heat exchanger 4.

[0100] In the present invention, specifically, the current output end of the internal combustion engine 16 is connected to the second inverter 17.

[0101] The second inverter 17 is used to receive the direct current output by the internal combustion engine 16 and then convert and output alternating current.

[0102] It should be noted that for the present invention, in the SOFC-ICE combined system, a fuel branch leading to the internal combustion engine is added to the fuel outlet of the reformer 6. The fuel outlet of the reformer 6 (specifically the hydrogen outlet) is connected to the fuel inlet of the internal combustion engine 16 (specifically the fuel inlet of the generator set of the internal combustion engine 16) through the eighth valve 58. The exhaust gas outlet of the internal combustion engine 16 is connected to the exhaust gas inlet of the ammonia heat exchanger 4, and the rest of the pipelines are the same as those of Figure 1 the single SOFC system shown.

[0103] The generator set of the internal combustion engine can use pure ammonia and ammonia-hydrogen mixed combustion. Therefore, it is necessary to control the flow rates of hydrogen and ammonia in the fuel branch after the reformer 6 and the ammonia in the ammonia gas cylinder according to the load size, and then introduce them into the internal combustion engine.

[0104] For the present invention, the original separate SOFC power generation system is coupled with an internal combustion engine generator set. The high-temperature exhaust gas discharged from the exhaust gas outlet of the internal combustion engine 16 is connected to the exhaust gas inlet (i.e., the waste gas inlet) of the ammonia heat exchanger 4, enabling waste heat utilization of the high-temperature exhaust gas of the internal combustion engine. A branch of the hydrogen gas at the outlet of the reformer 6 is connected to the fuel inlet of the internal combustion engine 16, which can provide hydrogen gas for the internal combustion engine 16 and reduce the emission of combustion pollutants.

[0105] For the power generation system of the present invention, it is an ammonia fuel SOFC-ICE combined system assisted by methane rich combustion. In the startup stage, the generator set of the internal combustion engine starts working first to output electric energy. The internal combustion engine burns ammonia gas. When the power generation system operates normally, since hydrogen gas is prepared by the reformer, the reformer can provide hydrogen gas for the internal combustion engine set. At this time, the internal combustion engine burns a mixture of ammonia and hydrogen.

[0106] When the power generation system operates normally, at low loads, the power generation system only requires the solid oxide fuel cell (SOFC) stack 7 to generate electricity alone; while at high loads, the power generation system can make the solid oxide fuel cell (SOFC) stack 7 and the internal combustion engine set generate electricity simultaneously.

[0107] Based on the above technical solutions, for the present invention, methane is subjected to rich combustion autothermal reforming in the porous medium burner 11 to provide heat and hydrogen gas for the startup of the power generation system. At the same time, in the heating modes of the reformer 6 and the solid oxide fuel cell (SOFC) stack 7, active heating with fuel gas (i.e., the methane rich combustion autothermal reforming process) is adopted, which can shorten the startup time of the power generation system.

[0108] For the present invention, in the catalytic reforming process of the methane and ammonia gas mixture in the reformer 6, due to the different endothermic and priority levels of their catalytic reactions, by optimizing the component concentration, the temperature gradient in the reformer 6 can be improved, and the mechanical damage of the reformer caused by different thermal stresses can be alleviated. Moreover, the present invention solves the problems of difficult combustion of ammonia gas in the afterburner 10 and relatively high nitrogen oxide emissions during the startup stage of the power generation system by increasing the method of methane rich combustion assistance. When the working condition suddenly rises, through methane rich combustion, the rapid supply of the fuel reformed gas of the power generation system is improved, avoiding the problem of reduced fuel utilization rate caused by insufficient heat when the waste heat of the solid oxide fuel cell (SOFC) stack 7 heats the reformer, and also alleviating the temperature fluctuations of each component of the system during variable load. During the normal operation stage of the SOFC-ICE combined power generation system, the present invention can achieve clean power supply of the system by introducing the reformed hydrogen gas into the internal combustion engine. The combined system not only improves the rapid startup of the system but also improves the energy efficiency of the system.

[0109] The power generation system of the present invention is an ammonia fuel SOFC power generation system based on methane rich combustion assistance, and also a power generation system using ammonia as the SOFC fuel. It adopts the methane rich combustion assistance technology. Through the rich combustion of methane in the porous medium burner, the autothermal reforming of methane is achieved, and high-temperature heat is also released, which can provide high-temperature fuel and heat source for the startup of the power generation system.

[0110] In the present invention, the fuel reforming process in the reformer 6 involves multiple components, such as CH4, NH3, H2 (hydrogen), CO2, CO, and H2O. Due to the different heat absorption amounts and component concentrations in the ammonia reforming and methane reforming processes, the temperature distribution of the reformer 6 will change, and the structure of the reformer needs to be optimized and designed.

[0111] For the power generation system provided by the present invention, the porous medium burner is not always used during the startup stage and the normal operation stage, and it needs to be controlled according to the system operation stage.

[0112] In the present invention, the afterburner 10 can burn the residual fuel gas in the outlet tail gas of the solid oxide fuel cell (SOFC) stack 7, but it is necessary to identify whether the afterburner needs to be started according to the system working conditions and the content of the residual fuel gas in the tail gas.

[0113] Regarding the usage stage of the porous medium burner in the SOFC power generation system, during system startup, the porous medium burner 11 needs to be used for methane rich combustion autothermal reforming. After normal operation, when the high-temperature tail gas at the outlet of the system stack is sufficient to maintain the temperature environment of each heat exchange component of the system and operate stably, the porous medium burner will no longer be used.

[0114] Regarding whether the afterburner is used in the system, when the temperature of the tail gas at the outlet of the system stack is sufficient to maintain the normal operation of the system, there is no need to burn the afterburner to increase the heat of the tail gas. At this time, the hydrogen in the tail gas can be recycled.

[0115] In order to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described below through specific embodiments.

[0116] Embodiment 1.

[0117] In Embodiment 1, the high-efficiency power generation system of the ammonia fuel solid oxide fuel cell provided by the present invention is a separate solid oxide fuel cell (SOFC) power generation system, as Figure 1 shown.

[0118] As Figure 1As shown in the figure, the high-efficiency power generation system of the ammonia fuel solid oxide fuel cell provided by the present invention, when it is a separate solid oxide fuel cell (SOFC) power generation system, includes a porous medium burner 11, a mixer 9, an ammonia heat exchanger 4, a first air heat exchanger 31, a second air heat exchanger 32, a blower 1, a solid oxide fuel cell SOFC stack 7, a supplementary combustor 10, a reformer 6, a methane gas cylinder 13, and an ammonia gas cylinder 12.

[0119] At this time, for the separate solid oxide fuel cell (SOFC) power generation system, its control method specifically includes the following working modes:

[0120] First, in the startup stage of the solid oxide fuel cell SOFC power generation system, first, open the third flow control valve 23 for adjusting methane, the sixth valve 56, the second flow control valve 22 for adjusting ammonia, the seventh valve 57, and the second valve 52. Methane undergoes rich combustion autothermal reforming with air in the porous medium burner 11 to obtain a methane reforming mixed gas mainly composed of H2 and CO.

[0121] Then, the methane reforming mixed gas output from the porous medium burner 11 and the ammonia passing through the second valve 52 enter the mixer 9 for uniform mixing, and then enter the reformer 6 for catalytic reforming to obtain a high-temperature hydrogen-rich mixed gas. This step can gradually reduce the temperature gradient in the reformer 6, alleviate carbon deposition during the catalytic reforming of methane, and increase the hydrogen content in the methane reforming mixed gas.

[0122] Then, after the high-temperature hydrogen-rich mixed gas and the air inhaled by the blower 1 enter from the anode fuel inlet and the cathode air inlet of the solid oxide fuel cell SOFC stack 7 respectively, the temperature of the solid oxide fuel cell SOFC stack 7 is increased.

[0123] Next, after the fuel and air come out of the solid oxide fuel cell SOFC stack 7, a part of the air and fuel enter the supplementary combustor 10 and then burn in the supplementary combustor 10. The high-temperature exhaust gas at the outlet of the supplementary combustor 10 further heats the equipment and gases in the reformer 6, the second air heat exchanger 32, the ammonia heat exchanger 4, and the first air heat exchanger 31 through convective heat transfer; another part of the air coming out of the stack 7 is used to heat the second air heat exchanger 32 and converges with other exhaust gases at the tail gas inlet of the first air preheater 31, and finally heats the solid oxide fuel cell SOFC power generation system to the normal working operation condition, that is, all components in the system reach the normal operation condition (the normal operation condition means the condition when the expected working state and function are achieved). [[ID= sixteen]]

[0124] In the methane rich-burn autothermal reforming process, air and methane are introduced into the porous medium burner 11, where they are first fully mixed. The mixture of fuel and oxidant is then ignited by a spark plug. The uniformity of the gas mixture can improve the efficiency of the methane autothermal reforming. The reaction equation is as follows:

[0125]

[0126] Among them, when the methane reformed gas and ammonia are mixed and a reforming reaction occurs in the reformer 6, the decomposition of ammonia is better than the reforming of methane. Methane reforming is a highly exothermic reaction, while ammonia is a weakly exothermic reaction. Therefore, as the ammonia component increases, the temperature gradient caused by the heat release of methane reforming will gradually decrease, which can improve the temperature uniformity in the reformer 6 and alleviate the structural damage caused by uneven thermal stress. The reaction equation is as follows:

[0127] 2NH3→N2+3H2, ΔH 298 =46kJ / mol;

[0128] CH4+H2O→CO+3H2, ΔH 298 =206kJ / mol;

[0129] ΔH 298 =-41 kJ / mol;

[0130] CH4+CO2→2CO+H2, ΔH 298 =247kJ / mol;

[0131] During the preheating process at the startup stage of the power generation system, due to the complex components in the fuel mixture, the electrochemical reaction process that occurs after the air and fuel enter the cathode and anode of the solid oxide fuel cell (SOFC) stack 7 is as follows:

[0132] Anode: 2H2+2O 2- →4e - +2H2O;

[0133] CO + 2O 2- →4e - +CO2;

[0134] Cathode: O2+4e - →2O 2- ;

[0135] 2. When the solid oxide fuel cell (SOFC) power generation system is operating normally (i.e., all components of the system have reached normal operating conditions), first, close the methane gas cylinder 13, open the ammonia gas cylinder 12, close the second valve 52, and open the first valve 51;

[0136] It should be noted that for the solid oxide fuel cell (SOFC) power generation system to operate normally, specifically: the temperatures of the solid oxide fuel cell (SOFC) stack 7 and the catalyst in the solid oxide fuel cell (SOFC) power generation system reach and stabilize at the temperatures required for the electrochemical reaction and catalytic reaction, such as 800 °C and 600 °C.

[0137] Then, the ammonia output from the ammonia gas cylinder 12 is heated in the ammonia heat exchanger 4 and then enters the reformer 6 to be further heated and undergo a catalytic reforming reaction to generate hydrogen H2.

[0138] Then, the hydrogen H2 coming out of the reformer 6 enters the anode fuel inlet of the solid oxide fuel cell (SOFC) stack 7, and the hydrogen and the oxygen in the air inhaled by the blower 1 respectively undergo an electrochemical reaction at the anode and cathode of the solid oxide fuel cell (SOFC) stack 7, thereby outputting electric energy.

[0139] It should be noted that after the power generation system operates normally, the waste heat at the stack outlet can maintain the temperature environment of the ammonia heat exchanger 4 and the reformer 6 of the system.

[0140] In addition, since the solid oxide fuel cell (SOFC) stack 7 cannot completely consume hydrogen, a hydrogen separator 15 can be added in the exhaust gas outlet direction of the solid oxide fuel cell (SOFC) stack 7 of the power generation system (specifically at the exhaust gas outlet of the ammonia heat exchanger 4) to recover the residual hydrogen in the exhaust gas.

[0141] III. After the solid oxide fuel cell (SOFC) power generation system operates normally, if the power supply load of the solid oxide fuel cell (SOFC) power generation system is at a medium - low load (i.e., the power supply load is within a preset low value range), open the third valve 53 to allow part of the hydrogen flowing out of the reformer 6 to enter the afterburner 10 through the third valve 53, thereby increasing the high - temperature exhaust gas flow at the outlet of the afterburner 10.

[0142] It should be noted that due to the medium - low load, the high - temperature exhaust gas flow at the exhaust gas outlet of the solid oxide fuel cell (SOFC) stack 7 decreases and is not sufficient to maintain the heat - exchange devices in the power generation system at an appropriate temperature. Therefore, at medium - low loads, part of the hydrogen needs to be added to obtain more heat by combustion to maintain the temperatures of the system components within a reasonable range.

[0143] IV. After the solid oxide fuel cell (SOFC) power generation system operates normally, when the power supply load of the solid oxide fuel cell (SOFC) power generation system increases from a medium-low load to a high load (i.e., the power supply load is within a preset high value range), open the methane gas cylinder 13 and the second valve 52. Methane undergoes rich combustion autothermal reforming in the porous medium burner 11 and then quickly mixes with ammonia in the mixer 9, enabling a large flow rate of fuel mixture to be reformed in the reformer 6 (specifically, reformed at an appropriate temperature, which is the reaction temperature with the optimal or relatively optimal catalytic reforming efficiency, such as 600 °C), compensating for the insufficient heat of the high-temperature exhaust gas at the outlet of the afterburner 10 under medium-low load, thereby maintaining the heat required for fuel gas reforming at a large flow rate.

[0144] Example 2.

[0145] In Example 2, the high-efficiency power generation system of the ammonia fuel solid oxide fuel cell provided by the present invention is a SOFC-ICE combined power generation system, that is, a combined power generation system of a solid oxide fuel cell with external ammonia reforming and an internal combustion engine, as Figure 2 shown.

[0146] The combined SOFC-ICE system mainly includes a SOFC power generation system and an internal combustion engine generator set. Among them, the exhaust of the internal combustion engine is connected to the exhaust gas inlet of the ammonia heat exchanger 4, and the fuel outlet of the reformer is connected to the fuel inlet of the internal combustion engine generator set through the eighth valve 58. The rest is arranged in the same layout as the separate SOFC power generation system.

[0147] For the combined power generation system of a solid oxide fuel cell and an internal combustion engine, its control method specifically includes the following working modes:

[0148] I. In the startup stage of the combined power generation system of a solid oxide fuel cell and an internal combustion engine (i.e., the SOFC-ICE combined power generation system), the generator set of the internal combustion engine 16 starts to work first. Ammonia burns and does work in the internal combustion engine 16, and the internal combustion engine 16 drives the generator installed thereon to work, thereby outputting electric energy. At this time, the high-temperature exhaust gas output by the internal combustion engine 16 is used to heat the ammonia heat exchanger 4 and the first air heat exchanger 31

[0149] It should be noted that due to the limited temperature of the high-temperature exhaust gas output by the internal combustion engine 16, it is used to heat the ammonia heat exchanger 4 and the first air heat exchanger 31.

[0150] Meanwhile, the porous medium burner 11 in the system obtains a high-temperature fuel mixture through methane-rich combustion autothermal reforming and catalytic reforming after mixing with ammonia. The high-temperature fuel gas is heated after entering the solid oxide fuel cell (SOFC) stack 7. At this time, since the solid oxide fuel cell (SOFC) stack 7 has not started normal operation, the air and fuel at the outlet of the solid oxide fuel cell (SOFC) stack 7 enter the afterburner 10 for combustion, and the resulting high-temperature gas heats the reformer 6, the ammonia heat exchanger 4, the first air heat exchanger 31, and the second air heat exchanger 32. This combined system not only outputs electrical energy during the startup phase but also prepares for heating the high-temperature components of the system.

[0151] II. After the solid oxide fuel cell and internal combustion engine combined power generation system (i.e., the SOFC-ICE combined power generation system) operates normally, if its power supply load is at a low load (i.e., the power supply load is within a preset low numerical range), the generator set of the internal combustion engine 16 is shut down, and only the solid oxide fuel cell (SOFC) stack 7 is retained for power generation. At this time, the control strategy for the fuel gas can refer to the separate SOFC power generation system described in Embodiment 1.

[0152] It should be noted that the normal operation of the solid oxide fuel cell and internal combustion engine combined power generation system (i.e., the SOFC-ICE combined power generation system) specifically means that when the temperature of the solid oxide fuel cell (SOFC) stack 7 stabilizes at the specified electrochemical reaction temperature, such as 800 °C.

[0153] III. After the solid oxide fuel cell and internal combustion engine combined power generation system (i.e., the SOFC-ICE combined power generation system) operates normally, if its power supply load is at a high load (i.e., the power supply load is within a preset high numerical range), not only the eighth valve 58 is opened, but also a branch is led out from the ammonia gas cylinder 12 to additionally supply ammonia to the internal combustion engine 16. At this time, the internal combustion engine 16 is in a state of mixed combustion of ammonia and hydrogen.

[0154] Compared with the prior art, the high-efficiency power generation system of the ammonia fuel solid oxide fuel cell provided by the present invention has the following beneficial effects:

[0155] 1. When the present invention considers the electrochemical reaction of ammonia in the anode of a fuel cell, first, during the electrochemical reaction of ammonia in the anode of a fuel cell, ammonia will first react with Ni in the catalyst to generate large particles of nickel nitride Ni3N, causing the anode structure to expand, the structure to change, and reducing the electrochemical activation performance of the battery. Second, during the electrochemical reaction process of ammonia, it needs to be decomposed into hydrogen atoms first, which is an endothermic process, causing the temperature at the inlet of the stack to drop, resulting in uneven heat load of the stack. Different thermal stresses will further affect the structure of the battery. All of these will increase the electrochemical performance and attenuation of the battery. In view of the problems existing in the current battery materials, the present invention adopts a method of externally reforming ammonia to produce high-concentration hydrogen, which can avoid the problems of many reaction processes of ammonia on the anode of a solid oxide fuel cell (SOFC) stack.

[0156] 2. The external reforming process of ammonia in the present invention is carried out under medium and high temperature catalytic conditions. By adopting the technologies of methane rich combustion assistance and ammonia premixing, the present invention can not only provide the high temperature environment required for ammonia catalytic reforming, but also methane and rich combustion intermediate products and ammonia have a mutual catalytic promotion effect, thus improving the catalytic reforming process of methane and ammonia. Moreover, since methane catalysis is a weak endothermic reaction and ammonia catalytic reforming is a strong endothermic reaction, optimizing the mixed catalytic process of the two can also reduce the temperature gradient and thermal stress gradient of the material during the reaction process, and increase the service life, durability and other characteristics of the reformer.

[0157] 3. The solid oxide fuel cell power generation system based on methane rich combustion and external reforming of ammonia provided by the present invention also has the characteristic of rapid response. Under start-up or variable operating conditions, the external reforming process of ammonia assisted by methane rich combustion will be regulated from the fuel source according to the system operating load. By changing the amount of methane rich combustion and the amount of ammonia, it can meet the output power of the solid oxide fuel cell (SOFC) stack and the temperature and heat requirements of devices such as ammonia heat exchangers and reformers. This method can optimize the regulation of each device under different loads, achieve faster response, and improve important indicators such as fuel utilization rate, energy efficiency and durability of the power generation system.

[0158] In summary, compared with the prior art, the efficient power generation system and control method of an ammonia fuel solid oxide fuel cell provided by the present invention are scientifically designed. In order to utilize ammonia efficiently, safely and reliably, after ammonia is externally reformed to produce hydrogen (that is, methane is subjected to rich combustion autothermal reforming in the porous medium burner 11 and then mixed with ammonia for catalytic reforming to obtain hydrogen), it then enters the fuel cell for power generation, and by using the optimized regulation method assisted by methane rich combustion, it plays a good role in the rapid response and component temperature balance of the power generation system, and has great practical significance.

[0159] The high-efficiency power generation system of the ammonia fuel solid oxide fuel cell provided by the present invention is a power generation system with the characteristics of fast response, low pollution and high performance, and has broad market application prospects.

[0160] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An efficient power generation system for an ammonia fuel solid oxide fuel cell, characterized in that, It includes a porous medium burner (11), a mixer (9), an ammonia heat exchanger (4), a first air heat exchanger (31), a second air heat exchanger (32), a blower (1), a solid oxide fuel cell SOFC stack (7), a supplementary combustor (10), a reformer (6), a methane gas cylinder (13) and an ammonia gas cylinder (12), where: The gas outlet of the ammonia gas cylinder (12) is communicated with one end of a second flow control valve (22); The other end of the second flow control valve (22) is respectively communicated with one ends of a first valve (51) and a second valve (52); The other end of the first valve (51) is communicated with the fuel cold flow inlet of the ammonia heat exchanger (4); The fuel hot flow outlet of the ammonia heat exchanger (4) is communicated with the fuel inlet of the reformer (6) through a three-way valve (14); The other end of the second valve (52) is communicated with the ammonia gas inlet of the mixer (9); The gas outlet of the methane gas cylinder (13) is communicated with one end of a third flow control valve (23); The other end of the third flow control valve (23) is communicated with the gas inlet of the porous medium burner (11); The gas outlet of the porous medium burner (11) is communicated with the methane gas inlet of the mixer (9); The mixed gas outlet of the mixer (9) is communicated with the fuel inlet of the reformer (6) through a three-way valve (14); The fuel outlet of the reformer (6) is respectively communicated with one ends of a fourth valve (54) and a third valve (53); The other end of the fourth valve (54) is communicated with the anode fuel inlet of the solid oxide fuel cell SOFC stack (7); The other end of the third valve (53) is communicated with the fuel gas inlet of the supplementary combustor (10); The air inlet of the blower (1) is communicated with the external atmospheric environment; The air outlet of the blower (1) is communicated with the inlet of a first flow control valve (21); The outlet of the first flow control valve (21) is communicated with the air inlet of the first air heat exchanger (31); The air outlet of the first air heat exchanger (31) is communicated with the air inlet of the second air heat exchanger (32); The air outlet of the second air heat exchanger (32) is communicated with the cathode air inlet of the solid oxide fuel cell SOFC stack (7); The anode tail gas outlet of the solid oxide fuel cell SOFC stack (7) is communicated with the fuel gas inlet of the supplementary combustor (10); The cathode tail gas outlet of the solid oxide fuel cell SOFC stack (7) is respectively communicated with the high-temperature waste gas inlet of the second air heat exchanger (32) and the air inlet of the supplementary combustor (10); The outlet of the supplementary combustor (10) is communicated with the high-temperature waste gas inlet of the reformer (6); The waste gas outlet of the reformer (6) is communicated with the waste gas inlet of the ammonia heat exchanger (4); The waste gas outlet of the ammonia heat exchanger (4) is communicated with the inlet of a hydrogen separator (15); The hydrogen separator (15) is used to recover the residual hydrogen in the system tail gas output by the ammonia heat exchanger (4); The exhaust gas outlet of the hydrogen separator (15) and the exhaust gas outlet of the second air heat exchanger (32) are connected to the exhaust gas inlet of the first air heat exchanger (31) after converging and intersecting; The hydrogen outlet of the hydrogen separator (15) is respectively connected to one ends of the fourth valve (54) and the third valve (53); The exhaust gas outlet of the first air heat exchanger (31) is connected to the external atmosphere; Sixth valves (56) and seventh valves (57) are respectively arranged on the connecting pipes between the ammonia gas cylinder (12) and the second flow control valve (22) and between the methane gas cylinder (13) and the third flow control valve (23).

2. The high-efficiency power generation system of the ammonia fuel solid oxide fuel cell according to claim 1, characterized in that, The cathode exhaust gas outlet of the solid oxide fuel cell SOFC stack (7) is connected to the air inlet of the afterburner (10) through the fifth valve (55).

3. The high-efficiency power generation system of an ammonia fuel solid oxide fuel cell according to claim 1, characterized in that The current output end of the solid oxide fuel cell SOFC stack (7) is connected to the first inverter (8); The first inverter (8) is used to receive the low-voltage direct current output by the solid oxide fuel cell SOFC stack (7) and then convert and output alternating current.

4. The high-efficiency power generation system of an ammonia fuel solid oxide fuel cell according to claim 1, characterized in that, The high-efficiency power generation system of the ammonia fuel solid oxide fuel cell is also connected to an internal combustion engine (16) to form a combined power generation system of the solid oxide fuel cell and the internal combustion engine. The specific structure is as follows: The fuel outlet of the reformer (6) is connected to the fuel inlet of the internal combustion engine (16) through the eighth valve (58); The gas outlet of the ammonia gas cylinder (12) is also connected to the air inlet of the fuel pump of the internal combustion engine (16); The exhaust gas outlet of the internal combustion engine (16) is connected to the exhaust gas inlet of the ammonia heat exchanger (4).

5. A control method for an efficient power generation system of an ammonia fuel solid oxide fuel cell according to any one of claims 1 to 3, characterized in that, It includes the following working modes: I. In the startup stage of the solid oxide fuel cell SOFC power generation system, first, open the third flow control valve (23) for regulating methane, the sixth valve (56), the second flow control valve (22) for regulating ammonia, the seventh valve (57), and the second valve (52). Methane undergoes rich combustion autothermal reforming with air in the porous medium burner (eleven) to obtain a methane reforming mixed gas mainly composed of H2 and CO; Then, the methane reforming mixed gas output by the porous medium burner (11) and the ammonia gas passing through the second valve (52) enter the mixer (9) for uniform mixing, and then enter the reformer (6) for catalytic reforming to obtain a high-temperature hydrogen-rich mixed gas. This step can gradually reduce the temperature gradient in the reformer (6), and can alleviate carbon deposition during the catalytic reforming of methane, and increase the hydrogen content in the methane reforming mixed gas; Then, after the high-temperature hydrogen-rich mixed gas and the air inhaled by the fan (1) enter from the anode fuel inlet and the cathode air inlet of the solid oxide fuel cell SOFC stack (7) respectively, the temperature of the solid oxide fuel cell SOFC stack (7) is increased; Next, after the fuel and air come out of the solid oxide fuel cell (SOFC) stack (7), a part of the air and fuel enter the afterburner (10) and then burn in the afterburner (10). The high-temperature exhaust gas at the outlet of the afterburner (10) further heats the equipment and gases in the reformer (6), the second air heat exchanger (32), the ammonia heat exchanger (4), and the first air heat exchanger (31) through convective heat transfer. Another part of the air coming out of the stack (7) is used to heat the second air heat exchanger (32) and converges with other exhaust gases at the exhaust gas inlet of the first air heat exchanger (31), and finally heats the solid oxide fuel cell (SOFC) power generation system to the normal operating condition.

6. The control method of the high-efficiency power generation system of the ammonia fuel solid oxide fuel cell according to claim 5, characterized in that, It also includes the following operating modes: Second, after the solid oxide fuel cell (SOFC) power generation system operates normally, first, close the methane gas cylinder (13), open the ammonia gas cylinder (12), close the second valve (52), and open the first valve (51). Then, the ammonia output from the ammonia gas cylinder (12) is heated in the ammonia heat exchanger (4) and then enters the reformer (6) to be further heated and undergoes a catalytic reforming reaction to produce hydrogen (H2). Then, the hydrogen (H2) coming out of the reformer (6) enters the anode fuel inlet of the solid oxide fuel cell (SOFC) stack (7). The hydrogen and the oxygen in the air inhaled by the blower (1) undergo an electrochemical reaction at the anode and cathode of the solid oxide fuel cell (SOFC) stack (7) respectively, thereby outputting electric energy.

7. A control method for an efficient power generation system of an ammonia fuel solid oxide fuel cell as claimed in claim 4, characterized in that, It includes the following operating modes: First, during the startup phase of the combined power generation system of the solid oxide fuel cell and the internal combustion engine, the generator set of the internal combustion engine (16) starts working first. Ammonia burns and does work in the internal combustion engine (16), and the internal combustion engine (16) drives the generator installed thereon to work, thereby outputting electric energy. At this time, the high-temperature exhaust gas output by the internal combustion engine (16) is used to heat the ammonia heat exchanger (4) and the first air heat exchanger (31). At the same time, the porous medium burner (11) in the system obtains a high-temperature fuel mixture through methane rich combustion autothermal reforming and catalytic reforming after mixing with ammonia. After the high-temperature fuel gas enters the solid oxide fuel cell (SOFC) stack (7), it is heated. At this time, since the solid oxide fuel cell (SOFC) stack (7) has not operated normally yet, the air and fuel at the outlet of the solid oxide fuel cell (SOFC) stack (7) enter the afterburner (10) for combustion, and the obtained high-temperature gas heats the reformer (6), the ammonia heat exchanger (4), the first air heat exchanger (31), and the second air heat exchanger (32).

8. The control method of the high-efficiency power generation system of the ammonia fuel solid oxide fuel cell according to claim 7, characterized in that, It also includes the following operating modes: Second, after the combined power generation system of the solid oxide fuel cell and the internal combustion engine operates normally, if its power supply load is at a low load, then turn off the generator set of the internal combustion engine (16) and only keep the solid oxide fuel cell (SOFC) stack (7) for power generation.

9. The control method of the high-efficiency power generation system of the ammonia fuel solid oxide fuel cell according to claim 7, characterized in that, It also includes the following operating modes: III. After the combined power generation system of the solid oxide fuel cell and the internal combustion engine operates normally, if its power supply load is at a high level, not only the eighth valve (58) is opened, but also a branch is led out from the ammonia gas cylinder (12) to additionally supply ammonia to the internal combustion engine (16). At this time, the internal combustion engine (16) is in a state of mixed combustion of ammonia and hydrogen.

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