Fuel cell power generation system and its control method

Abstract

The present invention relates to a fuel cell power generation system and a control method thereof. The system includes an ammonia decomposition device, an ammonia removal device, a fuel cell, a first membrane humidifier, a second membrane humidifier, a first gas-liquid separator, and an air compressor. The first membrane humidifier communicates between the ammonia decomposition device and the anode of the fuel cell. The second membrane humidifier communicates between the air compressor and the cathode of the fuel cell. The air compressor supplies compressed air to the cathode of the fuel cell. The first outlet of the fuel cell communicates with the anode of the fuel cell. The second outlet of the fuel cell communicates with the inlet of the first gas-liquid separator. The first outlet of the first gas-liquid separator communicates with the first membrane humidifier. The second outlet of the first gas-liquid separator communicates with the second membrane humidifier. In the present invention, the water obtained on the cathode side of the fuel cell is sent unidirectionally by the first gas-liquid separator to the first membrane humidifier on the anode side of the fuel cell, which can not only reduce the volume of the system, but also fundamentally solve the problem that the membrane on the anode side of the fuel cell is prone to drying.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and specifically to a fuel cell power generation system and a control method thereof.

Background Art

[0002] A fuel cell is a chemical device that directly converts the chemical energy of a fuel into electrical energy. It mainly performs an electrochemical reaction with oxygen or other oxidants and a fuel. In a fuel cell, fuel and air are sent to the anode and cathode of the fuel cell respectively, and electricity is produced. Hydrogen fuel is the optimal fuel in the current application of fuel cells. It has high efficiency, the fuel product is water, there is no slag and exhaust gas, and it does not pollute the environment. However, the storage of hydrogen is difficult. Currently, alternative fuel ammonia using hydrogen gas has advantages such as a high hydrogen content in ammonia, easy liquefaction, high energy density, no carbon emissions, high safety, and low fuel cost.

[0003] The proton exchange membrane fuel cell PEMFC is the current mainstream technology. There are mainly two problems in the application process. One is that protons in the perfluorosulfonic acid diaphragm in the proton exchange membrane fuel cell react with high-concentration ammonia to generate NH4+ ions, which easily cause irreversible attenuation of the fuel cell performance of the proton exchange membrane. It is necessary to connect a series of component devices such as ammonia decomposition, ammonia removal, and hydrogen fuel cells. The efficient integration of these component devices is related to complex energy management and system control policies, and the operation of the ammonia fuel cell system is likely to become unstable and the energy consumption is high. The other is that in the prior art, generally only the cathode of the fuel cell is humidified. When the proton membrane of the fuel cell stack is thick, drying of the membrane is likely to occur on the anode side of the fuel cell.

[0004] Chinese Patent Document CN 110277578A discloses an ammonia fuel cell system and an electric device including an ammonia decomposition reactor, a heating device, a hydrogen fuel cell, a DC / DC converter connected in sequence, an inverter, a battery pack, and a heat exchanger. The system has the advantages of being able to operate stably for a long time, forming a recycling process, having high flexibility, low energy consumption, and high system utilization rate. This patented technology solves the first problem, but the second problem should be solved.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of the drawbacks of the prior art, the present invention aims to solve the problem that when the proton membrane of a conventional fuel cell stack is thick, the anode side of the fuel cell is prone to membrane drying. Therefore, the present invention provides a fuel cell power generation system and its control method.

Means for Solving the Problems

[0006] The present invention uses the following technical solutions.

[0007] The present invention provides a fuel cell power generation system.

[0008] A fuel cell power generation system comprising an ammonia decomposition device for decomposing ammonia gas into hydrogen and nitrogen gases, a heating device installed inside the ammonia decomposition device for heating the gas and catalyst entering the ammonia decomposition device, an ammonia removal device communicating with the outlet of the ammonia decomposition device for removing undissociated ammonia gas, a fuel cell communicating with the ammonia removal device for oxidizing hydrogen gas as fuel to generate electrical energy, a conversion device connected to the fuel cell for boosting the voltage of the fuel cell, and a battery pack for storing the electrical energy generated by the fuel cell. The system further comprises a first membrane humidifier, a second membrane humidifier, a first gas-liquid separator, and an air compressor. The first membrane humidifier communicates between the ammonia decomposition device and the anode of the fuel cell. The second membrane humidifier communicates between the air compressor and the cathode of the fuel cell. The air compressor feeds compressed air into the cathode of the fuel cell. The first outlet of the fuel cell communicates with the anode of the fuel cell. The second outlet of the fuel cell communicates with the inlet of the first gas-liquid separator. The first outlet of the first gas-liquid separator communicates with the first membrane humidifier. The second outlet of the first gas-liquid separator communicates with the second membrane humidifier.

[0009] Furthermore, the system further includes a membrane separation device and a pressure swing adsorption separation device. The inlet of the pressure swing adsorption separation device communicates with the outlet of the membrane separation device. The outlet of the ammonia removal device communicates with the inlet of the membrane separation device. The outlet of the pressure swing adsorption separation device communicates with the anode of the fuel cell via the first membrane humidifier.

[0010] Furthermore, the system further includes a hydrogen gas booster pump connected between the outlet of the ammonia removal device and the inlet of the membrane separation device.

[0011] Furthermore, the system further includes an ejector. The inlet of the ejector communicates with the first outlet of the fuel cell. The first outlet of the ejector communicates with the outlet of the pressure swing adsorption separation device and the inlet of the ammonia decomposition device respectively. The second outlet of the ejector communicates with the anode of the fuel cell.

[0012] Preferably, the heating device includes an electric heater and an exhaust gas combustion device. Inside the ammonia decomposition device, two heat-conductive decomposition spaces, a first decomposition space and a second decomposition space, are provided. The exhaust gas combustion device is attached to the first decomposition space. The electric heater is attached to the second decomposition space. The first decomposition space communicates with the first inlet of the ammonia decomposition device and the first outlet of the ejector respectively, and the second decomposition space communicates with the second inlet of the ammonia decomposition device. Ammonia gas enters the second decomposition space, and both the first decomposition space and the second decomposition space communicate with the outlet of the ammonia decomposition device.

[0013] Preferably, two catalysts are filled in the second decomposition space along the flow direction of the ammonia gas. The proportion of the first type of catalyst arranged close to the upstream side of the ammonia gas gradually increases, and the proportion of the second type of catalyst arranged close to the downstream side of the ammonia gas gradually increases.

[0014] More preferably, the first type of catalyst adopts a Ru-based catalyst, the second type of catalyst adopts a Ni-based catalyst, and each catalyst is filled in a gradient so as to be distributed along the catalyst bed layer, and the catalyst particle size is 0.5 mm to 3 mm.

[0015] On the other hand, the present invention further provides a fuel cell power generation system.

[0016] A fuel cell power generation system comprising an ammonia decomposition device for decomposing ammonia gas into hydrogen-nitrogen gas, a heating device for heating the gas and catalyst entering the ammonia decomposition device installed inside the ammonia decomposition device, an ammonia removal device communicating with the outlet of the ammonia decomposition device for removing undecomposed ammonia gas, a fuel cell communicating with the ammonia removal device for oxidizing hydrogen gas as fuel to generate electrical energy, a conversion device connected to the fuel cell for boosting the voltage of the fuel cell, and a battery pack for storing the electrical energy generated by the fuel cell. The system further comprises a booster pump, a hydrogen gas circulation pump, a third membrane humidifier, a second gas-liquid separator, and an air compressor. The inlet of the booster pump is connected to the outlet of the ammonia removal device, the outlet of the booster pump communicates with the anode of the fuel cell, and the air compressor is used to send compressed air into the booster pump. The third membrane humidifier communicates between the pressure boosting pump and the cathode of the fuel cell. The first outlet of the fuel cell communicates with the inlet of the hydrogen gas circulation pump. The first outlet of the hydrogen gas circulation pump communicates with the inlet of the ammonia decomposition device. The second outlet of the hydrogen gas circulation pump communicates with the anode of the fuel cell. The second outlet of the fuel cell communicates with the inlet of the second gas-liquid separator. The outlet of the second gas-liquid separator communicates with the third membrane humidifier.

[0017] Furthermore, the system further includes a hydrogen gas pressure boosting pump and a membrane separation device. The first outlet of the membrane separation device communicates with the first outlet of the hydrogen gas circulation pump. The second outlet of the membrane separation device communicates with the pressure boosting pump. The inlet of the hydrogen gas pressure boosting pump is connected to the outlet of the ammonia removal device. The outlet of the hydrogen gas pressure boosting pump communicates with the inlet of the membrane separation device.

[0018] The present invention further provides a control method for a fuel cell power generation system, including the following steps, that is, Starting a heating device, reaching a predetermined temperature inside the ammonia decomposition device, feeding ammonia gas into the ammonia decomposition device, and decomposing the ammonia gas into hydrogen and nitrogen gas in step S101; The decomposed hydrogen and nitrogen enter the ammonia removal device to remove the undissociated ammonia gas in step S102; The hydrogen and nitrogen gas after deammoniation enters the hydrogen gas pressure boosting pump to boost the hydrogen and nitrogen gas to a predetermined pressure in step S103; The boosted hydrogen and nitrogen gas enters the membrane separation device to separate hydrogen gas for the first time, and the membrane-separated hydrogen and nitrogen gas enters the pressure swing adsorption separation device to separate hydrogen gas for the second time in step S104; The separated hydrogen and nitrogen gas enters the anode of the fuel cell after the humidity is adjusted by the first membrane humidifier, and the compressed air enters the cathode of the fuel cell after the humidity is adjusted by the second membrane humidifier. The gas generated from the anode of the fuel cell is refluxed to the ammonia decomposition device, the pressure swing adsorption separation device, and the anode of the fuel cell by the action of the ejector. The gas generated at the cathode of the fuel cell is separated into air and water by the first gas-water separator. The first gas-water separator includes step S105 of feeding the separated water into the first membrane humidifier and the second membrane humidifier respectively. The conversion device includes step S106 of boosting the fuel cell voltage and storing the generated electrical energy in the battery pack.

[0019] The present invention further provides a control method for a fuel cell power generation system, including the following steps, namely, Start the heating device, wait until the inside of the ammonia decomposition device reaches a predetermined temperature, feed ammonia gas into the ammonia decomposition device, and decompose the ammonia gas into hydrogen-nitrogen gas in step S201. The decomposed hydrogen-nitrogen gas enters the ammonia removal device to remove the undecomposed ammonia gas in step S202. The hydrogen-nitrogen gas after deammoniation enters the hydrogen gas booster pump, and the hydrogen-nitrogen gas is boosted to a preset pressure in step S203. The boosted hydrogen-nitrogen gas is sent into the membrane separation device to separate hydrogen gas by membrane separation. The membrane-separated hydrogen-nitrogen gas is boosted by the booster pump and then sent into the anode of the fuel cell. The compressed air is boosted by the booster pump and then sent into the third membrane humidifier. After the humidity is adjusted by the third membrane humidifier, it enters the cathode of the fuel cell. The gas generated at the anode of the fuel cell is refluxed to the ammonia decomposition device, the membrane separation device, and the anode of the fuel cell by the action of the hydrogen gas circulation pump. The gas generated at the cathode of the fuel cell is separated into air and water by the second gas-water separator. The second gas-water separator includes step S204 of feeding the separated water into the third membrane humidifier. The conversion device includes step S205 of boosting the fuel cell voltage and storing the generated electrical energy in the battery pack.

Effects of the Invention

[0020] The technical solution of the present invention has the following advantages.

[0021] A. The fuel cell power generation system provided by the present invention installs membrane humidifiers on the anode and cathode of the hydrogen fuel cell respectively, which can humidify the anode and cathode of the fuel cell respectively. In the prior art, only the cathode of the fuel cell is humidified. When the proton membrane of the fuel cell stack is thick, the problem that the membrane on the anode side of the fuel cell is likely to dry is solved.

[0022] B. The first membrane humidifier, the second membrane humidifier, and the third membrane humidifier used in the present invention all adopt Nafion membranes. The water obtained by the first gas-liquid separator on the cathode side of the fuel cell is sent unidirectionally to the side of the first membrane humidifier on the anode side of the fuel cell. When one side of the Nafion membrane is water and the other side is hydrogen gas, hydrogen gas will not penetrate. Compared with humidifying the anode of the hydrogen fuel cell with humidified air, this fuel cell power generation system not only reduces the volume of the system, but also fundamentally solves the problem that the membrane on the anode side of the fuel cell is likely to dry.

Brief Description of the Drawings

[0023] In the following, in order to more clearly explain the specific embodiments of the present invention, the attached drawings necessary for use in the specific embodiments will be briefly described. The attached drawings in the following description are part of the embodiments of the present invention. It is obvious to those skilled in the art that other attached drawings can be obtained based on these drawings without creative labor.

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Best Mode for Carrying Out the Invention

[0025] Next, with reference to the drawings, the technical solution of the present invention will be clearly and completely described. The described embodiments are obviously some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] In the description of the present invention, the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the purpose of simplifying the description and explanation of the present invention, and does not indicate or imply that the device or element needs to have a specific orientation and be structured and operated in a specific orientation, so it should not be understood as limiting the present invention. Also, the terms "first", "second", "third" are only for the purpose of explaining the purpose and should not be understood as indicating or implying relative importance.

[0027] In the description of the present invention, unless otherwise clearly defined and limited, the terms "attach", "connect", "couple" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection, a mechanical connection, an electrical connection, a direct connection, or an indirect connection through an intermediate medium, or a communication inside two elements. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific situation.

[0028] [Embodiment 1] As shown in FIG. 1, the present invention provides a fuel cell power generation system including an ammonia decomposition device 1, a heating device 2, an ammonia removal device 4, a fuel cell 13, a conversion device, a battery pack 18, a first membrane humidifier 11, a second membrane humidifier 15, a first gas-liquid separator 14, an air compressor 16, etc.

[0029] The heating device 2 is provided inside the ammonia decomposition device 1 and is for heating the gas and the catalyst. The ammonia decomposition device 1 is used to decompose ammonia gas into hydrogen and nitrogen gas.

[0030] The inlet of the ammonia removal device 4 communicates with the outlet of the ammonia decomposition device 1 to remove the undissociated ammonia gas. The fuel cell 13 communicates with the ammonia removal device 4 to oxidize hydrogen gas as fuel to generate electrical energy. The conversion device is connected to the fuel cell 13 to boost the voltage of the fuel cell 13. The battery pack 18 stores the electrical energy generated by the fuel cell 13. The first membrane humidifier 11 communicates between the ammonia decomposition device 1 and the anode of the fuel cell 13. The second membrane humidifier 15 communicates between the air compressor 16 and the cathode of the fuel cell 13, and the air compressor 16 sends compressed air into the cathode of the fuel cell 13. The first outlet of the fuel cell 13 communicates with the anode of the fuel cell 13, the second outlet of the fuel cell 13 communicates with the inlet of the first gas-liquid separator 14, the first outlet of the first gas-liquid separator 14 communicates with the first membrane humidifier 11, and the second outlet of the first gas-liquid separator 14 communicates with the second membrane humidifier 15.

[0031] The above fuel cell power generation system installs membrane humidifiers on the anode and cathode of the hydrogen fuel cell respectively, adopts a Nafion membrane, and in the prior art, the humidification problem is only solved at the cathode of the fuel cell. When the proton membrane of the fuel cell stack is thick, it solves the problem that the membrane on the anode side of the fuel cell is likely to dry out. One aspect of the present invention is to humidify the anode of the hydrogen fuel cell. It is to send the water obtained by the first gas-liquid separator 14 on the cathode side of the fuel cell 13 in one direction to the side of the first membrane humidifier 11 on the anode side of the fuel cell 13. When the Nafion membrane has water on one side and hydrogen on the other side, hydrogen gas cannot penetrate. The other aspect is to humidify using the anode exhaust gas of the fuel cell 13 and can also guarantee the purity of the hydrogen gas at the anode. However, there is insufficient humidification of the anode exhaust gas of the fuel cell 13. The present invention adopts the former humidification method among the above. Naturally, the combination of the above two is the optimal method proposed in this implementation, which not only reduces the system volume but also fundamentally solves the problem that the membrane on the anode side of the fuel cell 13 is likely to dry out. When the fuel cell 13 is anodically humidified using humid air, hydrogen gas permeates, and due to the hydrogen-nitrogen gas for the system, the hydrogen gas concentration further decreases until it cannot operate. During the operation process, humidification amount adjustment control is performed based on the parameter feedback of the operation inside the stack. The humidity control range is 10~90%RH, and the temperature control range is 10°C~45°C.

[0032] In this embodiment, the system further includes a membrane separation device 7 and a pressure swing adsorption separation device 9. The outlet of the membrane separation device 7 is connected to the inlet of the pressure swing adsorption separation device 9. The inlet of the membrane separation device 7 is connected to the outlet of the ammonia removal device 4. The outlet of the pressure swing adsorption separation device 9 communicates with the inlet of the first membrane humidifier 11. The volume ratio of hydrogen gas to nitrogen gas in the hydrogen-nitrogen gas after ammonia removal is 3:1. The hydrogen-nitrogen gas after ammonia removal is separated and purified by connecting the membrane separation device 7 and the pressure swing adsorption separation device 9. The gas first enters the membrane separation device 7 and then enters the pressure swing adsorption separation device 9. The circulated gas separated by pressure swing adsorption is returned to the membrane separation device 7 for recycling. The order of the membrane separation device 7 and the pressure swing adsorption separation device 9 cannot be interchanged. The upper limit of the hydrogen gas concentration separated by the membrane separation device 7 is 95%. It has a low cost and a good overall operating condition, but the hydrogen gas at this concentration does not meet the requirements for the fuel cell 13 system. The pressure swing adsorption separation device 9 can reach an upper limit of hydrogen gas concentration of 99.97% to 99.999% and can achieve high purity, but it has a high cost, cannot cope with fluctuations in the operating condition, and has a low yield in a low operating condition. According to the inventor's research, after the combination of membrane separation and pressure swing adsorption separation, it can simultaneously cope with low and high operating conditions, and extremely high yields can be obtained in both cases. Therefore, the order of the membrane separation device 7 and the pressure swing adsorption separation device 9 cannot be interchanged, and this design can simultaneously meet multiple hydrogen gas concentrations in order to guarantee the yield from the purification method, guarantee the performance of the fuel cell 13 from the humidification and equivalence ratio.

[0033] Specifically, when implementing, the membrane separation device 7 can adopt polymer membranes such as polysulfone, 2,6-dimethylphenyl ether (PPO), aramid, polyimide, modified polycarbonate, and cellulose acetate. The operating temperature is 20°C to 140°C, and hydrogen-nitrogen gas is separated by hydrogen gas permeation under a differential pressure of 0.1 to 3.2 MPa on both sides. The upper limit of the hydrogen gas concentration after membrane separation can reach 95%, and the upper limit of the yield can reach 95%. The pressure swing adsorption separation device 9 performs adsorption separation so that the purity of the hydrogen gas after separation is 99.97% to 99.999%, and the desorbed gas is returned to the membrane separation location for circulation.

[0034] In addition, all conventional PEMFC stack systems cannot operate stably under a hydrogen-nitrogen mixed gas. By connecting and using the membrane separation device 7 and the pressure swing adsorption separation device 9, stable operation becomes possible.

[0035] In this embodiment, a hydrogen gas booster pump 6 is further provided. The hydrogen gas booster pump 6 is connected between the ammonia removal device 4 and the membrane separation device 7 and is used to boost the hydrogen-nitrogen gas. The ammonia decomposition reaction is a reaction in which the equilibrium shifts in the reverse direction as the pressure increases. At the same time, when the pressure of the hydrogen-nitrogen gas is low, the fuel cell 13 cannot reach the required pressure of 0.15 - 0.2 A (1.5 - 2.0 bar) of the stack of the fuel cell 13. Therefore, the hydrogen-nitrogen gas after deammoniation is boosted using the hydrogen gas booster pump 6 to meet the requirements of the fuel cell 13.

[0036] In this embodiment, an ejector 12 is further installed in the system. The inlet of the ejector 12 communicates with the first outlet of the fuel cell 13. The first outlet of the ejector 12 communicates with the outlet of the pressure swing adsorption separation device 9 and the inlet of the ammonia decomposition device 1 respectively. The second outlet of the ejector 12 communicates with the anode of the fuel cell 13. The ejector 12 can reflux the gas generated corresponding to the anode of the fuel cell 13 to the anode of the fuel cell 13, can circulate and oxidize hydrogen, and can also exert a certain humidifying effect on the hydrogen gas. On the other hand, the gas generated corresponding to the anode of the fuel cell 13 can also be refluxed to the pressure swing adsorption device and enter the anode of the fuel cell 13 after passing through the first membrane humidifier 11. On the other hand, the gas generated corresponding to the anode of the fuel cell 13 can be refluxed to the ammonia decomposition device 1 to maintain the internal temperature of the ammonia decomposition device 1 by using the heat of the exhaust gas, and the hydrogen gas can also be recycled.

[0037] In this embodiment, the heating device 2 includes an electric heater and an exhaust gas combustion device. The inside of the ammonia decomposition device 1 is provided with two decomposition spaces that conduct heat while achieving two isolations. The first decomposition space communicates with the first outlet of the ejector 12 through the first inlet of the ammonia decomposition device 1, and the exhaust gas combustion device is attached to the first decomposition space. Ammonia gas enters the second decomposition space through the second inlet of the ammonia decomposition device 1, and the electric heater is attached to the second decomposition space. Both the first decomposition space and the second decomposition space communicate with the outlet of the ammonia decomposition device 1. Two catalysts are filled in the second decomposition space along the flow direction of the ammonia gas. The proportion of the first type of catalyst arranged on the side closer to the upstream side of the ammonia gas gradually increases, and the proportion of the second type of catalyst arranged on the side closer to the downstream side of the ammonia gas gradually increases.

[0038] The exhaust gas combustion device mainly has a heat supply function, and the electric heater has a temperature control function. The combustion device is such that the microchannel reactor catalytically oxidizes the exhaust gas to generate heat. Among them, the hydrogen gas concentration in the exhaust gas is 20% - 70%. The electric heater plays a role in temperature control to supplement heat. It includes, but is not limited to, enhancing heat exchange in such a way as contacting with the surround fins and embedding the other side of the fins into the inner tube catalyst bed layer. The electric heater can additionally provide thermal power closer to the gas downstream side based on the temperature control command, and can guarantee the performance of catalysts such as Ni-based catalysts at a pressure of 0.4 MPa. The microchannel reactor has a heat exchange function between the low-temperature gas and the high-temperature gas entering the device, realizes a low-temperature gas intake temperature of -5°C to 45°C, the temperature reaching the catalyst bed layer is 450°C to 600°C, and the temperature of the high-temperature gas after decomposition is less than 150°C when leaving the ammonia decomposition reactor.

[0039] Preferably, the first catalyst uses a Ru-based catalyst, and the second catalyst preferably uses a Ni-based catalyst. Along the direction in which ammonia gas flows, the Ru-based and Ni-based catalysts are loaded from top to bottom, filled in a gradient so that the catalysts are distributed along the catalyst bed layer. The catalyst particle size is 0.5 mm to 3 mm, and the shape is not limited to spherical porous particles and long porous particles. Among them, the operating temperature of the upstream part is 480 °C, and the downstream part can be operated at 500 to 650 °C based on a command. The exhaust gas combustion device employs hydrogen gas catalytic oxidation, and the operating concentration range is 20% to 70%.

[0040] Also, the proportion of the Ru multiphase catalyst arranged closer to the gas upstream side increases, and the proportion of the Ni-based catalyst arranged closer to the gas downstream side increases. The compositional ratio of the two types of catalysts being distributed in space includes, but is not limited to, multiple group distribution ratio methods such as free congestion and linear distribution. The ammonia decomposition temperature of the bed layer reaches a decomposition rate of 99.8% below 480 °C, and the method of utilizing the temperature gradient at a pressure of 0.4 MPa and a space velocity of 10000 mL / (gcat·h) results in a decomposition rate of 99.8%. The above decomposition rate means the one-way conversion rate of decomposing ammonia to produce hydrogen. Since the ammonia decomposition reaction is a reaction in which the equilibrium shifts in the reverse direction as the pressure increases, increasing the pressure poses a great challenge to the catalyst. The industrial treatment concept is to raise the temperature. However, due to some reasons, the Ru-based catalyst cannot be operated at too high a temperature. Otherwise, the carrier dissociates and pulverizes mechanically, and kinetically, the system absorbs heat violently at the intake end, the temperature of the heat exchange clamp point cannot be effectively controlled, and the heat exchange efficiency drops sharply. Therefore, an arrangement in which the Ru-based and Ni-based catalysts are distributed in a gradient in the upper and lower layers is adopted, and only in this way can the heat dissipation amount be spread throughout the tube side.

[0041] To further explain the action of the catalyst, the Ru-based catalyst has a low activation temperature and a high conversion rate. However, the carrier is vulnerable to heat. When it is necessary to increase the temperature during high-pressure operation, it rapidly absorbs heat at the front stage of the tube side, significantly reducing the heat exchange efficiency. The temperature at the rear end of the tube side is high, and the catalyst becomes powdered. The Ni-based catalyst has a high activation temperature and requires a high temperature. With only the Ni-based catalyst, the temperature at the front stage of the tube side is low, the heat exchange efficiency is significantly reduced, the system volume increases significantly, and although it is feasible, it becomes a design that is difficult to implement in practice. Therefore, it is necessary to use the two in combination.

[0042] In the above fuel cell power generation system, the ammonia decomposition device 1 is provided with a first inlet, a second inlet, and a second outlet. The first inlet of the ammonia decomposition device 1 communicates with the ejector 12. The second inlet of the ammonia decomposition device 1 communicates with the ammonia tank via a flow meter. The outlet of the ammonia decomposition device 1 communicates with the ammonia removal device 4. When specifically implemented, a first decomposition space and a second decomposition space separated by a heat-conducting metal structure are provided inside the ammonia decomposition device 1. As one embodiment, the heat-conducting metal structure is a single heat-conducting metal plate, and the first decomposition space and the second decomposition space are separated left and right. As another embodiment, the heat-conducting metal structure is a tubular structure. The exhaust gas enters the first decomposition space inside the tube, and the ammonia gas enters the second decomposition space outside the tube. By adopting the tubular structure compared with the heat-conducting metal plate, the heat quantity of the exhaust gas combustion can better heat the second decomposition space, and the heat utilization efficiency of the exhaust gas can be improved.

[0043] The above fuel cell power generation system connects the first membrane humidifier 11 and the ejector 12 to control the humidity of the hydrogen gas entering the anode of the fuel cell 13, and connects the second membrane humidifier 15 and the air compressor 16 to control the humidity of the air entering the cathode of the fuel cell 13. Thus, the first membrane humidifier 11, the second membrane humidifier 15, the ejector 12, and the air compressor 16 are used in combination to control the humidity of the hydrogen gas of the fuel cell 13. The ejector 12 is used to reflux the exhaust gas generated from the anode of the fuel cell 13 to the ammonia decomposition device 1, effectively utilizing the heat of the exhaust gas, providing heat by using an exhaust gas combustion device, and controlling the temperature with an electric heater. Thus, the ejector 12, the exhaust gas combustion device 2, and the electric heater are used in combination to control the temperature of the hydrogen gas of the fuel cell 13. The hydrogen gas pressurized by the hydrogen gas booster pump 6 enters the anode of the fuel cell 13 from the first inlet of the fuel cell 13. The ejector 12 refluxes the exhaust gas of the fuel cell 13 from the first inlet of the fuel cell 13 to the anode of the fuel cell 13. The air enters the cathode of the fuel cell 13 from the second inlet of the fuel cell 13 after being compressed by the air compressor 16, thereby realizing the pressure dynamic balance with the exhaust gas outlet of the anode of the fuel cell 13. Furthermore, the temperature, humidity, and pressure control of the hydrogen gas at the first inlet of the fuel cell 13 are realized, the exhaust of the stack anode at the first inlet of the fuel cell 13 is controlled and combined with the gas equivalent ratio, humidity, and pressure of the gas leaving from the first outlet of the fuel cell 13, the air at the second inlet of the fuel cell 13 is controlled in terms of pressure, humidity, and temperature, and the pressure dynamic balance between the gas at the first outlet of the fuel cell 13 is realized.

[0044] Here, the exhaust gas pressure control at the first outlet of the fuel cell 13 is equipped with a hydrogen gas booster pump 6 that utilizes a compressed air source based on Pascal's principle, and by connecting the compressed air entering from the second inlet of the fuel cell 13, the gas at the first outlet of the fuel cell 13 is pressurized. The pressure control range is 0.1 MPa to 0.4 MPa. The absolute value of the gas pressure increase at the first outlet of the fuel cell 13 is 1 to 4 times the pressure loss value of the compressed air, and pressure coordinated control is realized by a controller, and the numerical difference between the pressure at the first outlet of the fuel cell 13 and the pressure at the second outlet of the fuel cell 13 is controlled to be 0 to 0.08 MPa.

[0045] Here, since what is obtained by decomposing hydrogen through ammonia decomposition is a hydrogen-nitrogen mixture, generally, a fuel cell 13 system that uses pure hydrogen cannot accept it. As a result, the ejector 12 directly stops operating, and the circulation pump also causes the accumulation of nitrogen gas. The important issues are the equivalence ratio and humidity. The gas equivalence ratio control at the first outlet of the fuel cell 13 in this embodiment adjusts the gas equivalence ratio entering the fuel cell 13 system according to the set purity parameters of the membrane separation device 7 and the pressure swing adsorption separation device 9, the humidification part policy, and the stack operating conditions. The equivalence ratio is the equivalence ratio calculated based on the hydrogen gas consumed by the stack of the fuel cell 13, and the control range is 1.2 to 1.6. The tip pressure of the ejector 12 is controlled to be 1.35 to 1.5 MPa.

[0046] Here, the exhaust gas utilization control of the stack of the fuel cell 13 pumps the anode exhaust gas to the first inlet of the fuel cell 13 by the pressure of the pump through the ejector 12, and realizes the equivalence ratio and humidity control by controlling the rotation speed of the control ejector 12, and performs gas back pressure adjustment. The first membrane humidifier 11 and the second membrane humidifier 15 reverse osmose the gas water vapor from the cathode of the fuel cell 13 to the second inlet of the fuel cell 13.

[0047] In this embodiment, the fuel cell 13 is a PEMFC stack using a proton exchange membrane, that is, a perfluorosulfonic acid membrane and its modified membrane as the electrolyte, or an HT-PEMFC stack using phosphoric acid-PBI doped or a PBI / SiO2 composite membrane as the electrolyte. The operating temperature is 50 - 90 °C, the applicable gas is hydrogen gas with a purity of 75% - 99.999%, the ammonia gas concentration is less than 0.1 ppm, the use humidity range is 10% - 95% RH, and the use pressure range is 0.1 MPa - 0.4 MPa. For the HT-PEMFC stack, the applicable gas is hydrogen gas with a purity of 75% - 99.999%, the ammonia gas concentration is less than 100 ppm, the use humidity range is 60% - 99.9% RH, and the use pressure range is 0.1 MPa - 0.3 MPa.

[0048] In this embodiment, the air compressor 16 outputs compressed air at 0.1 to 0.4 MPa by a controller, the flow rate matches the stack power of the fuel cell 13, and the adjustment range of the equivalent ratio of the air entering the fuel cell 13 is 1.5 to 2.2. An air cleaner is installed at the air inlet of the air compressor 16 to filter particles in the environment.

[0049] In this embodiment, a plurality of sets of ammonia removal devices are provided. The ammonia removal device adsorbs ammonia in the hydrogen-nitrogen mixed gas coming out of the ammonia decomposition device by a physical adsorption method. The operating pressure range of the adsorbent is 0.1 to 0.4 MPa, the operating temperature is 30°C to 110°C, and the gas after adsorption from the device has an ammonia content of less than 0.1 ppm and a temperature of less than 45°C.

[0050] In this embodiment, the conversion device employs a DC / DC converter 17 to transport the electricity generated by the fuel cell 13 to the output end according to the CC, CV or CP mode and connect it to the battery pack 18 and an external DC load 20 or AC load 21. The capacitor 19 and the battery pack 18 have a BMS system and can change in response to external demand at a discharge rate of 0.1 to 10C, and can achieve adaptation of the DC / DC output terminal voltage and the DC bus load.

[0051] The hydrogen fuel cell power generation system of this embodiment has the advantages of high hydrogen storage density, high energy conversion efficiency, and low power generation cost. As a power generation unit, it has great application potential in mines, construction sites, islands, oilfield explorations, etc. far from the power grid or in data centers, offshore platforms, etc. with large power loads. Compared with the use cost of 2.5 to 2.8 yuan / kWh of a diesel power generation unit, the use cost of the ammonia hydrogen fuel cell 13 is 1.6 yuan / kWh. Moreover, the noise of the system is small, no pollutants are discharged, and it also has great application advantages in some biomedical fields and hospital scenes. Its application scenarios include power generation units, electric vehicles, electric ships, etc.

[0052] The operation process of the above fuel cell power generation system is as follows.

[0053] Ammonia gas passes through a flow meter and enters the ammonia decomposition device 1, where it is heated by a heating device 2 consisting of an electric heater and an exhaust gas combustion device. The heating device 2 heats the ammonia gas and the catalyst, decomposing the ammonia gas into hydrogen and nitrogen gases. Specifically, at startup, the two heating methods are heated together. After startup, the electric heating system only performs a temperature control function. The ammonia gas is decomposed into hydrogen gas and nitrogen gas in the catalyst bed layer, with the decomposition rate reaching 99.8% or more and the decomposition pressure increasing to 0.5 MPa according to the requirements at the rear end. This is achieved in cooperation with the rear-end electric heater and the catalyst bed layer with a high content of Ni-based catalyst. The decomposed hydrogen and nitrogen gases enter the ammonia removal device 4 after passing through the first control valve 3, where the undecomposed ammonia gas is removed, and hydrogen and nitrogen gases with an ammonia content of less than 0.1 ppm are obtained. After ammonia removal, the hydrogen and nitrogen gases enter the hydrogen gas booster pump 6 after passing through the second control valve 5. The pressurized hydrogen and nitrogen gases enter the membrane separation device 7 and then enter the pressure swing adsorption separation device 9 through the third control valve 8. The separated high-purity hydrogen (with a concentration of 99.97% or more) enters the first membrane humidifier 11 through the fourth control valve 10, and the separated desorbed gas is returned to the membrane separation device 7 through the fourth control valve 10. The separated high-purity hydrogen is adjusted in humidity by the first membrane humidifier 11 and then enters the anode side of the fuel cell 13 together with the hydrogen gas refluxed by the ejector 12. The air compressor 16 compresses air and then adjusts the humidity by the second membrane humidifier 15 and sends it to the cathode side of the fuel cell 13. The anode gas of the fuel cell 13 discharges exhaust gas from the first outlet of the fuel cell 13 and refluxes through the ejector 12 after passing through the fuel cell 13. The cathode gas of the fuel cell 13 passes through the first gas-liquid separator 14 from the second outlet of the fuel cell 13 and then discharges clean air and water. The first gas-liquid separator 14 pumps the collected liquid water to the first membrane humidifier 11 and the second membrane humidifier 15 respectively to maintain the water pressure of one of the membranes. The electrical energy output by the fuel cell 13 is connected to the battery pack 18 and the capacitor 19 through the DC / DC converter 17 and is also connected to the DC load 20, the inverter, and the AC load 21.

[0054] As shown in FIG. 3, the control method of the fuel cell power generation system includes the following steps.

[0055] Start the heating device, and when the inside of the ammonia decomposition device reaches a predetermined temperature (the temperature at the upstream part of the ammonia decomposition device 1 reaches 480°C, and the temperature at the downstream part reaches 500°C to 650°C), send ammonia gas into the ammonia decomposition device 1, and decompose the ammonia gas into hydrogen-nitrogen gas in step S101; In step S102, the decomposed hydrogen-nitrogen gas enters the ammonia removal device 4 to remove the undecomposed ammonia gas; In step S103, the hydrogen-nitrogen gas after deammoniation enters the hydrogen gas booster pump 6, and the hydrogen-nitrogen gas is pressurized to a predetermined pressure (0.1 MPa to 0.4 MPa); In step S104, the pressurized hydrogen-nitrogen gas enters the membrane separation device 7 to separate hydrogen gas for the first time, and the membrane-separated hydrogen-nitrogen gas enters the pressure swing adsorption separation device 9 to separate hydrogen gas for the second time; The separated hydrogen-nitrogen gas enters the anode of the fuel cell 13 after the humidity is adjusted by the first membrane humidifier 11, and the compressed air enters the cathode of the fuel cell 13 after the humidity is adjusted by the second membrane humidifier 15. The gas generated from the anode of the fuel cell 13 is refluxed to the ammonia decomposition device 1, the pressure swing adsorption separation device 9, and the anode of the fuel cell 13 by the action of the ejector 12. The gas generated at the cathode of the fuel cell 13 is separated into air and water by the first gas-liquid separator 14. The first gas-liquid separator 14 sends the separated water into the first membrane humidifier 11 and the second membrane humidifier 15 respectively in step S105; The conversion device includes step S106 of boosting the voltage of the fuel cell 13 and storing the generated electrical energy in the battery pack.

[0056] In addition to the effects described above, the beneficial effects of the fuel cell power generation system of this embodiment further include the following.

[0057] Compared with ammonia combustion and direct ammonia oxidation fuel cells (excluding SOFC), the power generation efficiency of the fuel cell that comes in after producing hydrogen by ammonia decomposition is high, and high-quality electrical energy can be obtained. Compared with other devices or methods for producing hydrogen by ammonia decomposition that rely on other high temperatures (800 - 900 °C), the energy efficiency of the catalyst for producing hydrogen by ammonia decomposition at 500 °C or lower used in the present invention is higher. Even for a single ammonia decomposition catalyst loading device with a similar reaction temperature, the present invention can realize the production of hydrogen by ammonia decomposition at a higher pressure with an equivalent decomposition rate by adjusting the relationship between the catalyst mixing ratio and temperature of the catalyst bed layer.

[0058] This example provides the possibility of adjusting the pressure, humidity, and equivalence ratio of the anode gas, suppresses the adverse effect of the nitrogen component on the fuel cell performance, and after supplying 95% pure hydrogen gas to the membrane separation, realizes the dual advantages of reducing the investment in pressure swing adsorption equipment and the fuel cell performance temperature.

[0059] This example uses the compressed air of the air compressor to pressurize the hydrogen gas and realizes the temperature control of the hydrogen gas and the air differential pressure. At the same time, since the present invention performs heat exchange with sufficient combustion on the exhaust gas of the hydrogen gas, the ammonia fuel cell system does not need to consume other fuels additionally, nor does it need to use a high proportion of electrical energy for heating the device for producing hydrogen by ammonia decomposition.

[0060] [Example 2] As shown in Figure 2, the present invention further provides another fuel cell power generation system, which includes an ammonia decomposition device 1, a heating device 2, an ammonia removal device 4, a fuel cell 13, a conversion device, a battery pack 18, a third membrane humidifier 24, a hydrogen gas circulation pump 23, a pressure boosting pump 22, a second gas-liquid separator 25, and an air compressor 16. The heating device 2 is installed inside the ammonia decomposition device 1, and the heating device 2 is for heating the gas and the catalyst. The ammonia decomposition device 1 is used to decompose ammonia gas into hydrogen and nitrogen gas.

[0061] The ammonia removal device 4 communicates with the outlet of the ammonia decomposition device 1 and is for removing the undecomposed ammonia gas. The fuel cell 13 and the ammonia removal device 4 communicate with each other, and hydrogen gas is oxidized as fuel to generate electrical energy. The conversion device is connected to the fuel cell 13 to step up the voltage of the fuel cell 13. The battery pack 18 stores the electrical energy generated by the hydrogen fuel cell 13. The booster pump 22 communicates between the ammonia decomposition device 1 and the anode of the fuel cell 13. The air compressor 16 is for sending compressed air into the booster pump 22. The third membrane humidifier 24 communicates between the booster pump 22 and the cathode of the fuel cell 13. The first outlet of the fuel cell 13 communicates with the inlet of the hydrogen gas circulation pump 23. The first outlet of the hydrogen gas circulation pump 23 communicates with the inlet of the ammonia decomposition device 1. The second outlet of the hydrogen gas circulation pump 23 communicates with the anode of the fuel cell 13. The second outlet of the fuel cell 13 communicates with the inlet of the third gas-liquid separator. The outlet of the third gas-liquid separator communicates with the third membrane humidifier 24. At the same time, further in the system, a hydrogen gas booster pump 6 and a membrane separation device 7 are installed. The hydrogen gas booster pump 6 and the membrane separation device 7 are sequentially connected between the ammonia removal device 4 and the booster pump 22, and the outlet of the membrane separation device 7 also communicates with the first outlet of the hydrogen gas circulation pump 23.

[0062] Compared with Example 1, in the fuel cell power generation system according to this example, the exhaust gas generated from the anode of the fuel cell 13 is sent back to the anode of the fuel cell 13 by the hydrogen gas circulation pump 23, and the anode exhaust gas of the fuel cell 13 is used for humidification, so as to ensure the purity of the hydrogen gas at the anode. However, there is insufficient humidification of the exhaust gas at the anode of the fuel cell 13. To address the problem of insufficient humidification of the hydrogen gas at the anode of the fuel cell 13, before entering the fuel cell 13, that is, the anode of the fuel cell 13, the hydrogen gas is pressurized to 0.2 - 0.3 MPa through the booster pump 22. The cathode of the fuel cell 13, that is, the pressure reduction side, is connected to the air compressor 16. The outlet of the pressurized side of the booster pump 22 is connected to the return pipeline of the hydrogen gas circulation pump 23. By controlling the specific operating conditions, the hydrogen gas circulation pump 23 recovers moisture and controls the humidity to 10% - 90% RH. The third membrane humidifier 24 realizes humidity exchange between the exhaust gas of the cathode of the fuel cell 13 and the outlet gas of the air compressor 16 of the fuel cell 13. The concentration of the hydrogen gas at the anode of the fuel cell 13 in Example 1 is 99.97% or more, and the concentration range of the hydrogen gas at the anode of the fuel cell 13 in Example 2 is 90 - 95% purity. According to the technical solution of Example 2, when the proton membrane of the stack of the fuel cell 13 is thick, the problem of membrane drying is likely to occur on the anode side of the fuel cell 13.

[0063] Here, there is a hydrogen gas circulation pump 23 on the anode side of the fuel cell 13, and the pressure entering the stack of the fuel cell 13 is controlled to 0.2 - 0.3 MPa. The air compressor 16 supplies air with an excess ratio of 1.6 - 1.8, and after the pressure passes through the pressure reduction side of the booster pump 22, it drops to 0.12 - 0.22 MPa. The second gas-liquid separator 25 separates gas and water on the cathode side of the fuel cell 13 to realize the control of the intake humidity of the cathode.

[0064] The operating process of the above fuel cell power generation system is as follows.

[0065] Ammonia gas passes through a flow meter and enters the ammonia decomposition device 1, where it is heated by an electric heater and an exhaust gas combustion device. The ammonia gas and the catalyst are heated, and the ammonia gas is decomposed into hydrogen and nitrogen gases. Specifically, two heating methods during startup are heated together. After startup, the electric heating system only performs a temperature control function. The ammonia gas is decomposed into hydrogen and nitrogen gases in the catalyst bed layer, and the decomposition rate reaches 99.8% or more. The decomposition pressure is increased to 0.5 MPa according to the needs of the rear end, which is achieved in cooperation with the rear end electric heater and the catalyst bed layer with a high content of Ni-based catalyst. The decomposed hydrogen and nitrogen gases enter the ammonia removal device 4 after passing through the first control valve 3, and the undecomposed ammonia gas is removed, and hydrogen gas with an ammonia content of less than 0.1 ppm can be obtained. After the hydrogen and nitrogen gases after ammonia removal pass through the second control valve 5, they enter the hydrogen gas booster pump 6. The pressurized hydrogen and nitrogen gases enter the membrane separation device 7. The obtained hydrogen gas with a purity of 90-95% directly enters the booster pump 22, and the hydrogen gas is pressurized by 1 to 4 times the other decompression value. The gas that did not pass through the membrane in the membrane separation device 7 burns in the electric heater and the combustion device to supply heat. The hydrogen gas enters the anode side of the fuel cell 13 together with the hydrogen gas refluxed by the hydrogen gas circulation pump 23. The hydrogen gas circulation pump 23 controls the humidity returned according to the command and the equivalent ratio entering the stack, and intermittently energizes and burns the exhausted hydrogen gas from the bypass to the electric heater and the combustion device to supply heat. The gas supplied to the cathode side of the fuel cell 13 is obtained by sending it from the air compressor 16 through the third membrane humidifier 24 at pump pressure. The anode gas is refluxed by the hydrogen gas circulation pump 23 after passing through the fuel cell 13, and the cathode gas discharges clean air and water after passing through the second gas-liquid separator 25. The second gas-liquid separator 25 separates the gas-liquid water and ensures the humidity control of the air sent into the stack. The electrical energy output from the fuel cell 13 is connected to the lithium battery pack 18 and the capacitor 19 through the DC / DC converter 17, and is connected to the DC load 20, the inverter, and the AC load 21.

[0066] As shown in FIG. 4, the control method of the fuel cell power generation system includes the following steps.

[0067] Start the heating device. When the inside of the ammonia decomposition device 1 reaches a predetermined temperature (the temperature of the upstream part of the ammonia decomposition device 1 reaches 480°C, and the temperature of the downstream part reaches 500°C to 650°C), send ammonia gas into the ammonia decomposition device 1 and decompose the ammonia gas into hydrogen-nitrogen gas in step S201; In step S202, the decomposed hydrogen-nitrogen gas enters the ammonia removal device 4 to remove the undecomposed ammonia gas; In step S203, the ammonia-removed hydrogen-nitrogen gas enters the hydrogen gas booster pump 6 to boost the pressure of the hydrogen-nitrogen gas to a predetermined pressure (0.1 MPa to 0.4 MPa); The pressurized hydrogen-nitrogen gas is sent into the membrane separation device 7, and hydrogen gas is membrane-separated. The membrane-separated hydrogen-nitrogen gas is pressurized by the booster pump 22 and sent into the anode of the fuel cell 13. After the compressed air is pressurized by the booster pump 22, it is sent into the third membrane humidifier 24, and the humidity is adjusted by the third membrane humidifier 24 and enters the cathode of the fuel cell 13. The gas generated at the anode of the fuel cell 13 is refluxed to the ammonia decomposition device 1, the membrane separation device 7, and the anode of the fuel cell 13 by the hydrogen gas circulation pump 23. The gas generated at the cathode of the fuel cell 13 is separated into air and water through the second gas-liquid separator 25, and the second gas-liquid separator 25 sends the separated water into the third membrane humidifier 24 in step S204; The conversion device includes step S205 of boosting the voltage of the fuel cell 13 and storing the generated electrical energy in the battery pack 18.

[0068] This embodiment has the advantages of high hydrogen storage density, high energy conversion efficiency, low investment cost, and low power generation cost. Since it does not require a pressure swing adsorption separation device, both the initial investment and volume of the system can be significantly reduced. The hydrogen gas with a purity of 90-95% provided by membrane separation combines the temperature, humidity, pressure, and equivalence ratio controlled by a hydrogen gas booster pump and a circulation pump to effectively solve the adverse effect on performance caused by the accumulation of nitrogen gas in the conventional fuel cell system. Moreover, by utilizing the energy recovery of the air compressor, it is used for boosting on the hydrogen gas side, effectively solving the problem of insufficient pressure of hydrogen and nitrogen gases in the system for producing hydrogen gas by ammonia decomposition. In the embodiment without a membrane separation device, this design method plays a more important role. This embodiment has the advantages of not being affected by seasons, having the superiority of long-term energy storage, high power generation efficiency, low electricity cost, small initial investment, low operation and maintenance pressure, and no pollutant emissions in application scenarios such as base station power supplies, power generation units, peak regulation of power plants, mine trucks, heavy trucks, and electric ships.

[0069] Obviously, the above-described embodiments are not intended to limit the implementation, but are only examples for clear explanation. Those skilled in the art can make other different forms of modifications or changes based on the above description. It is not necessary and impossible to list all the embodiments here. However, obvious modifications or changes are still within the protection scope of the present invention.

Description of Reference Numerals

[0070] Ammonia decomposition device 2 Heating device 3 First control valve 4 Ammonia removal device 5 Second control valve 6 Hydrogen gas booster pump 7 Membrane separation device 8 Third control valve 9 Pressure swing adsorption separation device 10 Fourth control valve 11 First membrane humidifier 12 ejector 13 fuel cell 14 first gas-liquid separator 15 second membrane humidifier 16 air compressor 17 DC / DC converter 18 battery pack 19 capacitor 20 DC load 21 AC load 22 booster pump 23 hydrogen gas circulation pump 24 third membrane humidifier 25 second gas-liquid separator

Claims

1. An ammonia decomposition device for decomposing ammonia gas into hydrogen and nitrogen gases, a heating device for heating the gas and catalyst that enter the ammonia decomposition device installed inside the ammonia decomposition device, An ammonia removal device that communicates with the outlet of the ammonia decomposition device and removes undecomposed ammonia gas, A fuel cell that communicates with the ammonia removal device and oxidizes hydrogen gas as fuel to generate electrical energy, A conversion device connected to the fuel cell that boosts the voltage of the fuel cell, A fuel cell power generation system comprising a battery pack for storing the electrical energy generated by the fuel cell, wherein The system further comprises a first membrane humidifier, a second membrane humidifier, a first gas-liquid separator, and an air compressor, The first membrane humidifier communicates between the ammonia decomposition device and the anode of the fuel cell, the second membrane humidifier communicates between the air compressor and the cathode of the fuel cell, and the air compressor feeds compressed air into the cathode of the fuel cell, A fuel cell power generation system characterized in that the first outlet of the fuel cell communicates with the anode of the fuel cell, the second outlet of the fuel cell communicates with the inlet of the first gas-liquid separator, the first outlet of the first gas-liquid separator communicates with the first membrane humidifier, and the second outlet of the first gas-liquid separator communicates with the second membrane humidifier.

2. The system further comprises a membrane separation device and a pressure swing adsorption separation device, the inlet of the pressure swing adsorption separation device communicates with the outlet of the membrane separation device, the outlet of the ammonia removal device communicates with the inlet of the membrane separation device, and the outlet of the pressure swing adsorption separation device communicates with the anode of the fuel cell via the first membrane humidifier. The fuel cell power generation system according to claim 1.

3. The system according to claim 2, further comprising a hydrogen gas booster pump connected between the outlet of the ammonia removal device and the inlet of the membrane separation device.

4. The system further comprises an ejector, an inlet of the ejector communicates with a first outlet of the fuel cell, a first outlet of the ejector communicates with an outlet of the pressure swing adsorption separation device and an inlet of the ammonia decomposition device respectively, and a second outlet of the ejector communicates with an anode of the fuel cell. The fuel cell power generation system according to claim 3 is characterized in that.

5. The heating device comprises an electric heater and an exhaust gas combustion device. Inside the ammonia decomposition device, two thermally conductive first decomposition spaces and second decomposition spaces are provided to be separated. The exhaust gas combustion device is attached to the first decomposition space, and the electric heater is attached to the second decomposition space. The first decomposition space communicates with a first inlet of the ammonia decomposition device and a first outlet of the ejector respectively. The second decomposition space communicates with a second inlet of the ammonia decomposition device. Ammonia gas enters the second decomposition space. The fuel cell power generation system according to claim 4 is characterized in that both the first decomposition space and the second decomposition space communicate with an outlet of the ammonia decomposition device.

6. Inside the second decomposition space, two catalysts are filled along the flow direction of the ammonia gas. The proportion of the first type of catalyst arranged close to the upstream side of the ammonia gas gradually increases, and the proportion of the second type of catalyst arranged close to the downstream side of the ammonia gas gradually increases. The fuel cell power generation system according to claim 5 is characterized in that.

7. The first type of catalyst adopts a Ru-based catalyst, the second type of catalyst adopts a Ni-based catalyst, and each of the catalysts is filled in a gradient manner so as to be distributed along the catalyst bed layer. The fuel cell power generation system according to claim 6 is characterized in that the catalyst particle size is 0.5 mm to 3 mm.

8. An ammonia decomposition device for decomposing ammonia gas into hydrogen-nitrogen gas and a heating device for heating the gas and catalyst entering the ammonia decomposition device installed inside the ammonia decomposition device. An ammonia removal device communicating with an outlet of the ammonia decomposition device for removing undecomposed ammonia gas. A fuel cell communicating with the ammonia removal device for oxidizing hydrogen gas as fuel to generate electrical energy. A conversion device connected to the fuel cell for boosting the voltage of the fuel cell. A fuel cell power generation system comprising a battery pack for storing the electrical energy generated by the fuel cell. The system further comprises a booster pump, a hydrogen gas circulation pump, a third membrane humidifier, a second gas-liquid separator, and an air compressor. The inlet of the booster pump is connected to the outlet of the ammonia removal device, and the outlet of the booster pump communicates with the anode of the fuel cell. The air compressor is used to send compressed air into the booster pump. The third membrane humidifier communicates between the booster pump and the cathode of the fuel cell. A first outlet of the fuel cell communicates with an inlet of the hydrogen gas circulation pump. A first outlet of the hydrogen gas circulation pump communicates with an inlet of the ammonia decomposition device. A second outlet of the hydrogen gas circulation pump communicates with the anode of the fuel cell. A second outlet of the fuel cell communicates with an inlet of the second gas-liquid separator. An outlet of the second gas-liquid separator communicates with the third membrane humidifier. A fuel cell power generation system characterized by the above.

9. The system further comprises a hydrogen gas booster pump and a membrane separation device. A first outlet of the membrane separation device communicates with a first outlet of the hydrogen gas circulation pump. A second outlet of the membrane separation device communicates with the booster pump. An inlet of the hydrogen gas booster pump is connected to the outlet of the ammonia removal device. An outlet of the hydrogen gas booster pump communicates with an inlet of the membrane separation device. The fuel cell power generation system according to claim 8, characterized by the above.

10. A control method for a fuel cell power generation system used in the fuel cell power generation system according to claim 6, comprising the following steps, namely: Starting a heating device, reaching a predetermined temperature inside the ammonia decomposition device, sending ammonia gas into the ammonia decomposition device, and decomposing the ammonia gas into hydrogen and nitrogen gas in step S101. The decomposed hydrogen and nitrogen gas enters the ammonia removal device to remove the undissociated ammonia gas in step S102. The hydrogen and nitrogen gas after deammoniation enters the hydrogen gas booster pump to increase the pressure of the hydrogen and nitrogen gas to a predetermined pressure in step S103. The pressurized hydrogen and nitrogen gas enters the membrane separation device to separate hydrogen gas for the first time, and the membrane-separated hydrogen and nitrogen gas enters the pressure swing adsorption separation device to separate hydrogen gas for the second time in step S104. The separated hydrogen-nitrogen gas is adjusted in humidity by the first membrane humidifier and then enters the anode of the fuel cell. Compressed air is adjusted in humidity by the second membrane humidifier and then enters the cathode of the fuel cell. The gas generated from the anode of the fuel cell is refluxed to the ammonia decomposition device, the pressure swing adsorption separation device, and the anode of the fuel cell by the action of the ejector. The gas generated at the cathode of the fuel cell is separated into air and water by the first gas-liquid separator. The first gas-liquid separator includes step S105 of feeding the separated water into the first membrane humidifier and the second membrane humidifier respectively. The conversion device includes step S106 of boosting the voltage of the fuel cell and storing the generated electrical energy in the battery pack. A control method for a fuel cell power generation system, characterized by the above.

11. A control method for a fuel cell power generation system used in the fuel cell power generation system according to claim 9, including the following steps, namely: Starting the heating device until the inside of the ammonia decomposition device reaches a predetermined temperature, feeding ammonia gas into the ammonia decomposition device, and decomposing the ammonia gas into hydrogen-nitrogen gas in step S201. The decomposed hydrogen-nitrogen gas enters the ammonia removal device to remove the undecomposed ammonia gas in step S202. The hydrogen-nitrogen gas after deammoniation enters the hydrogen gas booster pump to boost the hydrogen-nitrogen gas to a preset pressure in step S203. The boosted hydrogen-nitrogen gas is fed into the membrane separation device to separate hydrogen gas by membrane separation. The membrane-separated hydrogen-nitrogen gas is boosted by the booster pump and then fed into the anode of the fuel cell. Compressed air is fed into the third membrane humidifier after being boosted by the booster pump, adjusted in humidity by the third membrane humidifier, and then enters the cathode of the fuel cell. The gas generated at the anode of the fuel cell is refluxed to the ammonia decomposition device, the membrane separation device, and the anode of the fuel cell by the action of the hydrogen gas circulation pump. The gas generated at the cathode of the fuel cell is separated into air and water by the second gas-liquid separator. The second gas-liquid separator includes step S204 of feeding the separated water into the third membrane humidifier. The conversion device includes step S205 of boosting the fuel cell voltage and storing the generated electrical energy in the battery pack. A control method for a fuel cell power generation system, characterized by the above.

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