Ammonia cracking system

Abstract

The invention provides an ammonia cracking system, which relates to the technical field of ammonia cracking, and comprises an ammonia supply device used for providing ammonia gas; the cracking equipment is connected with the ammonia supply equipment and is used for cracking the ammonia gas from the ammonia supply equipment to obtain first mixed gas, and the first mixed gas comprises the ammonia gas, hydrogen and nitrogen; a gas inlet of the absorption equipment is communicated with the cracking equipment, the absorption equipment is used for absorbing ammonia gas in the first mixed gas to obtain second mixed gas, the second mixed gas comprises hydrogen and nitrogen, and a gas outlet of the absorption equipment is used for being communicated with an anode of the fuel cell so as to convey the second mixed gas to the anode of the fuel cell; by means of the ammonia cracking system, the problem that in the prior art, mixed gas generated after ammonia cracking is adopted to be conveyed to the anode of the fuel cell to serve as fuel, and a catalyst and a proton membrane of the fuel cell are poisoned by ammonia gas in the mixed gas is solved.

Description

Technical Field

[0001] This invention relates to the field of ammonia cracking technology, and more specifically, to an ammonia cracking system. Background Technology

[0002] Fuel cells typically use hydrogen as fuel. Hydrogen is usually stored in high-pressure cylinders. Hydrogen is difficult to compress and has a low hydrogen content per unit volume, making storage and transportation relatively difficult. Current technologies generally use ammonia cracking to obtain hydrogen. Ammonia contains about 17% hydrogen, resulting in a high hydrogen content, and ammonia is easily liquefied.

[0003] The prior art discloses a machine thermal management method for an on-board ammonia cracking hydrogen production system for an ammonia engine. This method uses the heat generated by the combustion exhaust gas of the internal combustion engine and the ammonia oxidizer to preheat and crack the ammonia liquid, and sends the mixture of cracked hydrogen and ammonia into the internal combustion engine. In this prior art, since the internal combustion engine is not sensitive to the ammonia content, the internal combustion engine can work normally.

[0004] However, for fuel cells, ammonia can poison the catalyst and proton exchange membrane. Therefore, if a mixture of cracked hydrogen and ammonia is to be delivered to the anode of a fuel cell as fuel, the cracked ammonia must be removed. Otherwise, the ammonia will damage the anode of the fuel cell. Summary of the Invention

[0005] The main objective of this invention is to provide an ammonia cracking system to solve the problem in the prior art where the ammonia in the mixed gas produced after ammonia cracking is transported to the anode of a fuel cell as fuel, and the ammonia in the mixed gas poisons the fuel cell catalyst and proton exchange membrane.

[0006] To achieve the above objectives, according to one aspect of the present invention, an ammonia cracking system is provided, comprising:

[0007] Ammonia supply equipment is used to supply ammonia gas.

[0008] A pyrolysis unit connected to an ammonia supply unit is used to pyrolyze ammonia gas from the ammonia supply unit to obtain a first mixed gas, the first mixed gas including ammonia, hydrogen and nitrogen.

[0009] An absorption device is provided, with its inlet connected to a pyrolysis device, for absorbing ammonia from a first mixed gas to obtain a second mixed gas, which includes hydrogen and nitrogen. The outlet of the absorption device is connected to the anode of a fuel cell to deliver the second mixed gas to the anode of the fuel cell, so that the fuel cell generates electricity.

[0010] Furthermore, the ammonia supply equipment includes: a liquid ammonia storage tank, which stores liquid ammonia;

[0011] An evaporation device is connected to a liquid ammonia storage tank. The evaporation device is used to evaporate liquid ammonia from the liquid ammonia storage tank to form ammonia gas, and then transport the ammonia gas to a cracking device for cracking to obtain a first mixed gas.

[0012] Furthermore, the ammonia cracking system also includes a first heat exchange loop;

[0013] The evaporation device includes a first heat exchanger, which has a first heat exchange channel and a second heat exchange channel that are independent of each other. The first heat exchange channel is connected to a first heat exchange circuit to feed a heated medium into the first heat exchange channel. The second heat exchange channel is connected to a liquid ammonia storage tank so that the liquid ammonia in the second heat exchange channel exchanges heat with the medium in the first heat exchange channel.

[0014] Furthermore, the pyrolysis equipment includes a combustion chamber and a pyrolysis chamber. A second heat exchanger is also connected between the second heat exchange channel and the combustion chamber. The second heat exchanger has a third heat exchange channel and a fourth heat exchange channel that are independent of each other. The two ends of the third heat exchange channel are connected to the second heat exchange channel and the pyrolysis chamber, respectively, so as to pyrolyze the ammonia gas from the third heat exchange channel through the pyrolysis chamber to obtain a mixed gas.

[0015] The fourth heat exchange channel is connected to the combustion chamber so that the mixed products generated after combustion in the combustion chamber can be transported to the fourth heat exchange channel to exchange heat with the liquid ammonia in the third heat exchange channel; the mixed products include nitrogen, water, oxygen and nitrogen oxides.

[0016] Furthermore, the ammonia cracking system also includes: a third heat exchanger, which is installed on the pipeline between the first heat exchanger and the second heat exchanger. The third heat exchanger has a fifth heat exchange channel and a sixth heat exchange channel that are independent of each other. The two ends of the fifth heat exchange channel are respectively connected to the second heat exchange channel and the third heat exchange channel. The two ends of the sixth heat exchange channel are respectively connected to the inlet of the cracking chamber and the absorption equipment, so that the inlet of the absorption equipment is connected to the cracking equipment through the third heat exchanger.

[0017] Furthermore, the ammonia cracking system also includes a buffer tank, which is connected to the absorption unit and is used to depressurize the hydrogen and nitrogen from the absorption unit in order to deliver the hydrogen and nitrogen to the anode of the fuel cell.

[0018] Furthermore, the ammonia cracking system also includes: a desorption tank, which is connected to the anode of the fuel cell and is used to heat the anode exhaust gas generated by the anode of the fuel cell to obtain a first product system; the desorption tank is connected to the combustion chamber of the cracking equipment to transport the first product system to the combustion chamber for combustion in the combustion chamber to generate mixed products, the first product system including nitrogen, hydrogen and water;

[0019] The first heat exchange circuit is connected to the desorption tank so as to heat the desorption tank using the medium in the first heat exchange circuit.

[0020] Furthermore, the first heat exchange circuit includes: a first heat exchange tube and a second heat exchange tube, the two ends of the first heat exchange channel are respectively connected to the first heat exchange tube and the second heat exchange tube, the end of the first heat exchange tube away from the first heat exchange channel is connected to the inlet of the desorption tank, and the end of the second heat exchange tube away from the first heat exchange channel is connected to the outlet of the desorption tank.

[0021] The fourth heat exchanger has two independent heat exchange channels, the seventh and the eighth. The two ends of the eighth heat exchange channel are connected to the outlet of the absorption equipment and the inlet of the desorption tank, respectively.

[0022] The fuel cell is also connected to a circulating water tank, which is connected to a first pipe. Water with a first preset temperature generated by the fuel cell is discharged from the first pipe. One end of the seventh heat exchange channel is connected to the first pipe, and the other end of the seventh heat exchange channel is connected to the circulating water tank through a second pipe.

[0023] Furthermore, the ammonia cracking system also includes: a tail gas treatment device, which is connected to the fourth heat exchange channel and is used to treat nitrogen oxides in the product system of the fourth heat exchange channel after heat exchange.

[0024] Furthermore, the ammonia cracking system also includes a heating unit that works in conjunction with the desorption tank. The heating unit is designed to be openable and closed so that the desorption tank can be heated by activating the heating unit.

[0025] By applying the technical solution of this invention, an absorption device is installed in the ammonia cracking system to absorb the ammonia gas obtained after cracking liquid ammonia, resulting in a second mixed gas containing hydrogen and nitrogen. This second mixed gas is then input into the anode of a fuel cell to generate electricity. However, because the anode of a fuel cell typically contains a noble metal catalyst, nitrogen in the ammonia gas may chemically adsorb and react with the active sites on the catalyst surface, occupying these sites and reducing the catalyst's activity. This affects the rate and efficiency of the electrochemical reaction. Under certain conditions, ammonia gas may also undergo a chemical reaction to generate corrosive substances. Ammonia, such as ammonium salts, can corrode the anode material, reducing its service life and mechanical strength. If ammonia is present in the anode of a fuel cell for a long time, byproducts or unreacted ammonia produced during the reaction may accumulate and precipitate in the anode's porous structure, causing blockage of the anode pores, hindering the transport and diffusion of fuel and reactants, and reducing the performance of the fuel cell. Therefore, this application includes an absorption device that can absorb the ammonia produced by the pyrolysis equipment to ensure that it does not damage the anode of the fuel cell, so that the fuel cell can generate electricity normally and output the electricity at the fuel cell cathode. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 A process flow diagram of the ammonia cracking system according to the present invention is shown.

[0028] The above figures include the following reference numerals:

[0029] 1. Liquid ammonia storage tank; 2. Pyrolysis equipment; 201. Combustion chamber; 202. Pyrolysis chamber; 3. Absorption equipment; 4. Anode of fuel cell; 5. First heat exchanger; 6. Second heat exchanger; 7. Third heat exchanger; 8. Buffer tank; 9. Desorption tank; 10. Fourth heat exchanger; 11. Circulating water tank; 12. Tail gas treatment equipment; 13. Heating unit; 14. Switch valve; 15. Flow control valve; 16. Fuel cell cathode; 17. Pressure reducing valve. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] Fuel cells typically use hydrogen as fuel. Hydrogen is usually stored in high-pressure cylinders. Hydrogen is difficult to compress and has a low hydrogen content per unit volume, making storage and transportation relatively difficult. Current technologies generally use ammonia cracking to obtain hydrogen. Ammonia contains about 17% hydrogen, resulting in a high hydrogen content, and ammonia is easily liquefied.

[0032] The prior art discloses a machine thermal management method for an on-board ammonia cracking hydrogen production system for an ammonia engine. This method uses the heat generated by the combustion exhaust gas of the internal combustion engine and the ammonia oxidizer to preheat and crack the ammonia liquid, and sends the mixture of cracked hydrogen and ammonia into the internal combustion engine. In this prior art, since the internal combustion engine is not sensitive to the ammonia content, the internal combustion engine can work normally.

[0033] However, for fuel cells, ammonia can poison the catalyst and proton exchange membrane. Therefore, if a mixture of cracked hydrogen and ammonia is to be delivered to the anode of a fuel cell as fuel, the cracked ammonia must be removed. Otherwise, the ammonia will damage the anode of the fuel cell.

[0034] Therefore, the purpose of this application is to provide an ammonia cracking system to address the above problems, thereby solving the problem in the prior art where the mixed gas produced after ammonia cracking is transported to the anode of a fuel cell as fuel, and the ammonia in the mixed gas poisons the fuel cell catalyst and proton exchange membrane.

[0035] This application provides an ammonia cracking system, including: an ammonia supply device for supplying ammonia gas;

[0036] The cracking device 2 is connected to the ammonia supply device and is used to crack the ammonia gas from the ammonia supply device to obtain a first mixed gas, which includes ammonia gas, hydrogen gas and nitrogen gas.

[0037] Absorption device 3, the inlet of absorption device 3 is connected to pyrolysis device 2, and is used to absorb ammonia in the first mixed gas to obtain a second mixed gas, the second mixed gas including hydrogen and nitrogen. The outlet of absorption device 3 is connected to the anode 4 of fuel cell to deliver the second mixed gas to the anode 4 of fuel cell so that the fuel cell generates electricity.

[0038] By providing an absorption device 3, the ammonia gas obtained after the liquid ammonia is cracked by the cracking device 2 can be absorbed to obtain a second mixed gas. The second mixed gas includes hydrogen and nitrogen. The second mixed gas is input into the anode 4 of the fuel cell so that the fuel cell generates electrical energy and outputs it from the cathode 16 of the fuel cell.

[0039] Because the anode of a fuel cell typically contains a precious metal catalyst, nitrogen in ammonia may chemically adsorb and react with the active sites on the catalyst surface, occupying these active sites and reducing the catalyst's activity, thus affecting the rate and efficiency of the electrochemical reaction. Under certain conditions, ammonia may undergo chemical reactions to generate corrosive substances, such as ammonium salts. These corrosive products can corrode the anode material, reducing its service life and mechanical strength. If ammonia is present in the anode of the fuel cell for a long time, byproducts generated during the reaction or unreacted ammonia may accumulate and precipitate in the anode's pore structure, causing blockage of the anode pores, hindering the transport and diffusion of fuel and reactants, and reducing the performance of the fuel cell. Therefore, this application provides an absorption device 3, which can absorb the ammonia generated by the cracking device 2 to ensure that it does not damage the anode 4 of the fuel cell, so that the fuel cell can generate electricity normally.

[0040] Furthermore, the ammonia supply equipment includes: a liquid ammonia storage tank 1, which stores liquid ammonia;

[0041] An evaporation device is connected to a liquid ammonia storage tank 1. The evaporation device is used to evaporate the liquid ammonia from the liquid ammonia storage tank 1 to form ammonia gas, and then transport the ammonia gas to a cracking device 2 for cracking to obtain a first mixed gas.

[0042] This application incorporates an evaporation device to evaporate liquid ammonia in a liquid ammonia storage tank 1 to form ammonia gas. The ammonia gas is then transported to a cracking device 2 for cracking to obtain a first mixed gas. The first mixed gas includes ammonia gas, hydrogen gas, and nitrogen gas. The first mixed gas is then transported to an absorption device 3 to absorb the ammonia gas present in the first mixed gas. As a result, the mixed gas after absorbing the ammonia gas can be transported to the anode 4 of a fuel cell as fuel, so that the anode 4 of the fuel cell can generate electrical energy.

[0043] Furthermore, the ammonia cracking system also includes a first heat exchange loop;

[0044] The evaporation device includes a first heat exchanger 5, which has a first heat exchange channel and a second heat exchange channel that are independent of each other. The first heat exchange channel is connected to a first heat exchange circuit to feed a heated medium into the first heat exchange channel. The second heat exchange channel is connected to a liquid ammonia storage tank 1 so that the liquid ammonia in the second heat exchange channel exchanges heat with the medium in the first heat exchange channel.

[0045] This application provides a first heat exchange circuit and a first heat exchanger 5, which transports the heated medium in the first heat exchange circuit to the first heat exchange channel, so as to provide the first heat exchange channel to preheat the ammonia gas in the second heat exchange channel, so that the preheated ammonia gas can be directly cracked when it is transported to the cracking equipment 2.

[0046] Furthermore, the pyrolysis device 2 includes a combustion chamber 201 and a pyrolysis chamber 202. A second heat exchanger 6 is also connected between the second heat exchange channel and the combustion chamber 201. The second heat exchanger 6 has a third heat exchange channel and a fourth heat exchange channel that are independent of each other. The two ends of the third heat exchange channel are connected to the second heat exchange channel and the pyrolysis chamber 202 respectively, so as to pyrolyze the ammonia gas from the third heat exchange channel through the pyrolysis chamber 202 to obtain the first mixed gas.

[0047] The fourth heat exchange channel is connected to the combustion chamber 201 so that the mixed products generated after combustion in the combustion chamber 201 are transported to the fourth heat exchange channel to exchange heat with the liquid ammonia in the third heat exchange channel; the mixed products include nitrogen, water, oxygen and nitrogen oxides.

[0048] The pyrolysis device 2 in this application includes a combustion chamber 201 and a pyrolysis chamber 202. A second heat exchanger 6 is also provided between the second heat exchange channel and the combustion chamber 201. During the initial start-up, ammonia gas is first delivered to the combustion chamber 201 for combustion. Since the combustion chamber 201 and the pyrolysis chamber 202 are connected during start-up, the temperature of the pyrolysis chamber 202 will also rise as the ammonia gas burns in the combustion chamber 201. When the temperature of the pyrolysis chamber 202 rises to the temperature at which ammonia gas is pyrolyzed, the ammonia gas can be directly introduced into the pyrolysis chamber 202 for pyrolysis. By providing the second heat exchanger 6, the ammonia gas from the liquid ammonia storage tank 1 can be further heated to increase the temperature of the ammonia gas as much as possible so that it can be pyrolyzed in the pyrolysis chamber 202.

[0049] Meanwhile, by providing a combustion chamber 201, during the cracking of ammonia, there is no need to use an additional heat source to heat the cracking chamber 202. Instead, the temperature of the cracking chamber 202 can be gradually increased by first heating and cracking the ammonia through the combustion chamber 201.

[0050] Furthermore, the ammonia cracking system also includes a third heat exchanger 7, which is installed on the pipeline between the first heat exchanger 5 and the second heat exchanger 6. The third heat exchanger 7 has a fifth heat exchange channel and a sixth heat exchange channel that are independent of each other. The two ends of the fifth heat exchange channel are respectively connected to the second heat exchange channel and the third heat exchange channel. The two ends of the sixth heat exchange channel are respectively connected to the inlet of the cracking chamber 202 and the air inlet of the absorption device 3, so that the air inlet of the absorption device 3 is connected to the cracking device 2 through the third heat exchanger 7.

[0051] This application utilizes a third heat exchanger 7. The two ends of the fifth heat exchange channel of the third heat exchanger 7 are connected to the second and third heat exchange channels, respectively. The two ends of the sixth heat exchange channel are connected to the inlets of the cracking chamber 202 and the absorption device 3, respectively. Ammonia gas from the liquid ammonia storage tank 1 first enters the second heat exchange channel of the first heat exchanger 5, where it undergoes initial heat exchange with the heated medium in the first heat exchange channel. After heat exchange, the ammonia gas enters the fifth heat exchange channel of the third heat exchanger 7 through the second heat exchange channel. The first mixed gas produced by cracking the ammonia gas in the cracking chamber 202 enters the sixth heat exchange channel, where it undergoes a second heat exchange with the ammonia gas in the fifth heat exchange channel, further increasing the temperature of the ammonia gas exiting the fifth heat exchange channel. The first mixed gas, containing ammonia, hydrogen, and nitrogen, enters the absorption device 3 through the inlet of the absorption device 3. The absorption device 3 can absorb the ammonia gas in the first mixed gas. In this embodiment, the absorption device 3 is an absorption tank. The medium in the absorption device 3 is water. Water can absorb ammonia in the first mixed gas to obtain nitrogen, hydrogen and a small amount of water. Because ammonia cracking at high temperature is a reversible reaction, the first mixed gas after cracking contains hydrogen and nitrogen, as well as a portion of ammonia. The first mixed gas coming out of the cracking chamber 202 is under high pressure. After passing through the third heat exchanger 7 and exchanging heat with the ammonia in the fifth heat exchange channel, it enters the absorption device 3 to complete the absorption of ammonia in the first mixed gas. In this embodiment, the medium in the absorption device 3 can be an acid that can react with ammonia, in addition to water. The mixed products generated by the combustion of ammonia in the combustion chamber 201 enter the fourth heat exchange channel through the fourth heat exchange channel. Because the fifth heat exchange channel is connected to the third heat exchange channel, the ammonia can be heat-exchanged again in the second heat exchanger 6 to further increase the temperature of the ammonia entering the cracking chamber 202.

[0052] Furthermore, the ammonia cracking system also includes a buffer tank 8, which is connected to the absorption device 3 and is used to reduce the pressure of hydrogen and nitrogen from the absorption device 3 so as to deliver hydrogen and nitrogen to the anode 4 of the fuel cell.

[0053] By providing a buffer tank 8 connected to the absorption device 3, the buffer tank 8 can reduce the pressure of hydrogen and nitrogen from the absorption device 3, typically to 140 kPa, before feeding them into the anode 4 of the fuel cell to ensure that the fuel cell can operate continuously.

[0054] Furthermore, the ammonia cracking system also includes: a desorption tank 9, which is connected to the anode 4 of the fuel cell and is used to heat the anode tail gas generated by the anode 4 of the fuel cell to obtain a first product system; the desorption tank 9 is connected to the combustion chamber 201 of the cracking device 2 to transport the first product system to the combustion chamber 201 for combustion in the combustion chamber 201 to generate mixed products, the first product system including nitrogen, hydrogen and water;

[0055] The first heat exchange circuit is connected to the desorption tank 9 so as to heat the desorption tank 9 using the medium in the first heat exchange circuit.

[0056] The anode 4 of the fuel cell is also connected to a desorption tank 9. The medium in the desorption tank 9 is water, and the inside of the desorption tank 9 is always under low pressure and high temperature. Under these conditions, the solubility of ammonia in water is low, which is conducive to the desorption of ammonia. During the operation of the fuel cell, the anode produces anode tail gas, which contains nitrogen, hydrogen and water. The anode tail gas is input into the desorption tank 9 to exchange heat with the liquid in the desorption tank 9, and at the same time, the anode tail gas is desorbed under low pressure to obtain nitrogen, hydrogen, ammonia and water. The desorbed anode tail gas can be directly sent to the combustion chamber 201 to realize the combustion of the first product system through the combustion chamber 201 and generate mixed products, wherein the first product system includes nitrogen, hydrogen and water.

[0057] Furthermore, the first heat exchange circuit includes: a first heat exchange tube and a second heat exchange tube, the two ends of the first heat exchange channel are respectively connected to the first heat exchange tube and the second heat exchange tube, the end of the first heat exchange tube away from the first heat exchange channel is connected to the water inlet of the desorption tank, and the end of the second heat exchange tube away from the first heat exchange channel is connected to the water outlet of the desorption tank 9.

[0058] The fourth heat exchanger 10 has an independent seventh heat exchange channel and an eighth heat exchange channel. The two ends of the eighth heat exchange channel are connected to the outlet of the absorption device 3 and the inlet of the desorption tank 9, respectively.

[0059] The fuel cell is also connected to a circulating water tank 11, which is connected to a first pipe. Water with a first preset temperature generated by the fuel cell is discharged from the first pipe. One end of the seventh heat exchange channel is connected to the first pipe, and the other end of the seventh heat exchange channel is connected to the circulating water tank 11 through a second pipe.

[0060] By providing a fourth heat exchanger 10, the water generated by the anode 4 of the fuel cell at a first preset temperature during operation can exchange heat with the water containing ammonia in the self-absorption device 3. After heat exchange, the water containing ammonia is input into the desorption tank 9, and the water after heat exchange returns to the circulating water tank 11. The absorption device 3 is under high pressure and low temperature, and the ammonia has a high solubility in water, which is conducive to the absorption of ammonia in water. The desorption tank 9 is under low pressure and high temperature, and the ammonia has a low solubility in water, which is conducive to the desorption of ammonia. The desorbed gas includes hydrogen, water, nitrogen and ammonia, and this part of the gas is transported to the combustion chamber 201 for combustion.

[0061] Furthermore, the ammonia cracking system also includes: a tail gas treatment device 12, which is connected to the fourth heat exchange channel and is used to treat nitrogen oxides in the product system of the fourth heat exchange channel after heat exchange.

[0062] Furthermore, the ammonia cracking system also includes a heating unit 13, which cooperates with the desorption tank 9. The heating unit 13 is configured to be openable and closable so that the desorption tank 9 can be heated by activating the heating unit 13.

[0063] The mixture produced after combustion in the combustion chamber 201 is transported to the exhaust gas treatment device 12 after heat exchange between the liquid ammonia in the second heat exchanger 6 and the liquid ammonia in the third heat exchange channel. The exhaust gas treatment device 12 treats the nitrogen oxides in the product system in the fourth heat exchange channel after heat exchange, and then the treated gas is discharged to avoid nitrogen oxides being emitted into the atmosphere and causing environmental pollution. The exhaust gas treatment device 12 can be an exhaust gas treatment tank, and the medium contained in the exhaust gas treatment device 12 can be an alkaline solution, such as sodium hydroxide solution or potassium hydroxide solution. They can all react chemically with nitrogen oxides to convert them into harmless substances, that is, to catalytically reduce nitrogen oxides in high-temperature exhaust gas into nitrogen and oxygen. Alternatively, a three-way catalytic converter can be installed in the exhaust gas treatment device to catalytically reduce nitrogen oxides in high-temperature exhaust gas into nitrogen and oxygen.

[0064] Example 1

[0065] like Figure 1As shown, when the ammonia cracking system of this application is started, the temperature in the cracking chamber 202 is too low to crack the ammonia. All the ammonia to be cracked can be directly fed into the combustion chamber 201 for combustion. During the combustion process, the temperature in the cracking chamber 202 gradually rises. After reaching the cracking temperature of the cracking chamber 202, the proportion of gas directly supplied from the cracking chamber 202 to the combustion chamber 201 is gradually reduced. The anode tail gas generated by the anode 4 of the fuel cell is then used as the combustion gas input into the combustion chamber 201 for combustion. At this time, the liquid ammonia in the liquid ammonia storage tank 1 enters the second heat exchange channel in the first heat exchanger 5. An inlet ammonia pipe is also provided between the liquid ammonia storage tank 1 and the second heat exchange channel. A switch valve 14 and a flow control valve 15 are installed on the inlet ammonia pipe. The switch valve 14 is opened, and the opening degree of the flow control valve 15 is simultaneously controlled, so that the liquid ammonia in the liquid ammonia storage tank 1 enters the second heat exchange channel through the inlet ammonia pipe and exchanges heat with the medium transported from the self-desorption tank 9 to the first heat exchange channel. The medium is the high-temperature liquid in the desorption tank 9. After heat exchange in the first heat exchanger 5, the liquid ammonia is reduced to ammonia gas at room temperature. The medium after heat exchange enters the absorption device 3 through the first heat exchange tube. The ammonia gas at room temperature enters the fifth heat exchange channel in the third heat exchanger 7 as a cold flow. The heat flow is the first mixed gas produced after ammonia cracking. The components of the first mixed gas include ammonia, hydrogen, and nitrogen. After heat exchange, the ammonia gas is initially heated, and the first mixed gas is cooled to room temperature. The initially heated ammonia gas is then transported as a cold flow again. The heat flow enters the second heat exchanger 6. The heat flow is the mixed product generated by the combustion of ammonia in the combustion chamber 201. The mixed product includes nitrogen, water, nitrogen oxides and oxygen. The two exchange heat in the second heat exchanger 6 to obtain the finally heated ammonia, which is then transported to the cracking chamber 202. At the same time, the temperature of the mixed product decreases after the heat exchange and it is transported to the tail gas treatment device 12. The tail gas treatment device 12 treats the nitrogen oxides in the mixed product to obtain nitrogen, water and oxygen, which can then be discharged into the atmosphere.

[0066] The pyrolysis chamber 202 is a high-temperature pyrolysis chamber with a temperature above 500℃. Ammonia gas enters the pyrolysis chamber 202 for pyrolysis. Because the pyrolysis process of ammonia gas is a reversible reaction, ammonia gas is pyrolyzed in the pyrolysis chamber 202 to produce nitrogen gas, hydrogen gas, and a small amount of residual ammonia gas. The pyrolyzed mixed gas is then heated by the third heat exchanger 7 to obtain room temperature gas, which is then sent to the absorption device 3. The absorption device 3 contains water, which can absorb the ammonia gas in the pyrolyzed mixed gas to obtain nitrogen gas, hydrogen gas, and a small amount of water. That is, the gas at this time has a certain humidity. The nitrogen gas, hydrogen gas, and a small amount of water are sent to the buffer tank 8 for buffering to reduce the gas pressure. Then, the pressure reducing valve 17 located between the buffer tank 8 and the anode 4 of the fuel cell is opened to send the reduced pressure gas to the anode 4 of the PEM fuel cell. The fuel cell consumes some hydrogen gas, and the remaining nitrogen gas, hydrogen gas, and water gas are sent to the desorption tank 9 to remove the gas in the desorption tank 9. A portion of the ammonia gas is converted into nitrogen, hydrogen, and a small amount of ammonia. This mixed gas is then transported to combustion chamber 201 for combustion, providing a heat source for the cracking chamber 202 to crack the ammonia. Cold water containing ammonia in absorption device 3 is used as a cold flow through the fourth heat exchanger 10 to exchange heat with a portion of the circulating water generated by the fuel cell. After heat exchange, the hot water containing ammonia is introduced into desorption tank 9 for desorption. A portion of the circulating water after heat exchange is returned to the fuel cell. Absorption device 3 is under high pressure and low temperature, and the solubility of ammonia in water is high, which is conducive to the absorption of ammonia in water. Desorption tank 9 is under low pressure and high temperature, and the solubility of ammonia in water is low, which is conducive to the desorption of ammonia. In the initial start-up stage, since the fuel cell is not yet working and the temperature of the circulating water in the fuel cell is low, a heating unit 13 is provided. The heating unit 13 can heat the desorption tank 9 to increase the water temperature of the desorption tank 9 so that the liquid ammonia can be evaporated into ammonia gas.

[0067] Through the ammonia cracking system of this application, from the input of liquid ammonia, to the vaporization of liquid ammonia, the heating of low-temperature ammonia, the cracking of ammonia, the provision of the required cracking temperature in the cracking chamber 202, the removal of ammonia remaining in the cracked gas, and the input to the anode 4 of the fuel cell, this application provides a complete energy source and system layout for ammonia cracking. It can realize the evaporation of liquid ammonia to obtain ammonia, the cracking of ammonia, and the gas input to the anode of the fuel cell after cracking does not contain ammonia, thereby protecting the anode 4 of the fuel cell and preventing damage to the fuel cell during use.

[0068] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: The ammonia cracking system of this application, by providing an absorption device 3, can absorb the ammonia gas obtained after the cracking of liquid ammonia by the cracking device 2, obtaining a second mixed gas. The second mixed gas includes hydrogen and nitrogen. This second mixed gas is input into the anode 4 of the fuel cell, so that the fuel cell generates electrical energy, which is output from the cathode 16 of the fuel cell. Because the anode of the fuel cell typically contains a noble metal catalyst, the nitrogen element in the ammonia gas may chemically adsorb and react with the active sites on the catalyst surface, occupying these active sites, leading to a decrease in catalyst activity and affecting the rate and efficiency of the electrochemical reaction. Under certain conditions, ammonia may undergo a chemical reaction to produce corrosive substances, such as ammonium salts. These corrosive products can corrode the anode material, reducing the anode's service life and mechanical strength. If ammonia is present in the anode of a fuel cell for a long time, byproducts or unreacted ammonia produced during the reaction may accumulate and precipitate in the anode's porous structure, causing blockage of the anode pores, hindering the transport and diffusion of fuel and reactants, and reducing the performance of the fuel cell. Therefore, this application provides an absorption device 3, which can absorb the ammonia produced by the cracking device 2 to ensure that it will not damage the anode 4 of the fuel cell, so that the fuel cell can generate electricity normally.

[0069] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0070] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0071] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0072] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0073] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An ammonia cracking system, characterized in that, include: Ammonia supply equipment, wherein the ammonia supply equipment is used to supply ammonia gas; The pyrolysis device (2) is connected to the ammonia supply device and is used to pyrolyze the ammonia gas from the ammonia supply device to obtain a first mixed gas, the first mixed gas including ammonia, hydrogen and nitrogen. An absorption device (3) is provided, the inlet of which is connected to the cracking device (2) for absorbing ammonia in the first mixed gas to obtain a second mixed gas, the second mixed gas including hydrogen and nitrogen. The outlet of the absorption device (3) is connected to the anode (4) of the fuel cell to deliver the second mixed gas to the anode (4) of the fuel cell so that the fuel cell generates electricity.

2. The ammonia cracking system according to claim 1, characterized in that, The ammonia supply equipment includes: A liquid ammonia storage tank (1) contains liquid ammonia; An evaporation device is connected to the liquid ammonia storage tank (1). The evaporation device is used to evaporate the liquid ammonia from the liquid ammonia storage tank (1) to form the ammonia gas, and to transport the ammonia gas to the cracking device (2) for cracking to obtain the first mixed gas.

3. The ammonia cracking system according to claim 2, characterized in that, The ammonia cracking system also includes a first heat exchange loop; The evaporation device includes a first heat exchanger (5), which has a first heat exchange channel and a second heat exchange channel that are independent of each other. The first heat exchange channel is connected to the first heat exchange circuit to feed the heated medium into the first heat exchange channel. The second heat exchange channel is connected to the liquid ammonia storage tank (1) so that the liquid ammonia in the second heat exchange channel exchanges heat with the medium in the first heat exchange channel.

4. The ammonia cracking system according to claim 3, characterized in that, The pyrolysis equipment includes a combustion chamber (201) and a pyrolysis chamber (202). A second heat exchanger (6) is also connected between the second heat exchange channel and the combustion chamber. The second heat exchanger has a third heat exchange channel and a fourth heat exchange channel that are independent of each other. The two ends of the third heat exchange channel are respectively connected to the second heat exchange channel and the pyrolysis chamber (202) to pyrolyze the ammonia gas from the third heat exchange channel through the pyrolysis chamber (202) to obtain the first mixed gas. The fourth heat exchange channel is connected to the combustion chamber (201) so that the mixed products generated after combustion in the combustion chamber (201) are transported to the fourth heat exchange channel to exchange heat with the liquid ammonia in the third heat exchange channel; wherein the mixed products include nitrogen, water, oxygen and nitrogen oxides.

5. The ammonia cracking system according to claim 4, characterized in that, The ammonia cracking system also includes: The third heat exchanger (7) is installed on the pipeline between the first heat exchanger (5) and the second heat exchanger (6). The third heat exchanger (7) has a fifth heat exchange channel and a sixth heat exchange channel that are independent of each other. The two ends of the fifth heat exchange channel are respectively connected to the second heat exchange channel and the third heat exchange channel. The two ends of the sixth heat exchange channel are respectively connected to the inlet of the pyrolysis chamber (202) and the absorption device (3), so that the inlet of the absorption device (3) is connected to the pyrolysis device (2) through the third heat exchanger (7).

6. The ammonia cracking system according to claim 1, characterized in that, The ammonia cracking system also includes: A buffer tank (8) is connected to the absorption device (3) for depressurizing hydrogen and nitrogen from the absorption device (3) to deliver the hydrogen and nitrogen to the anode (4) of the fuel cell.

7. The ammonia cracking system according to claim 3, characterized in that, The ammonia cracking system also includes: A desorption tank (9) is connected to the anode (4) of the fuel cell and is used to heat the anode tail gas generated by the anode (4) of the fuel cell to obtain a first product system; the desorption tank (9) is connected to the combustion chamber (201) of the cracking device (2) to transport the first product system to the combustion chamber (201) for combustion in the combustion chamber (201) to generate the mixed product, wherein the first product system includes nitrogen, hydrogen and water; The first heat exchange circuit is connected to the desorption tank (9) so as to heat the desorption tank (9) using the medium in the first heat exchange circuit.

8. The ammonia cracking system according to claim 7, characterized in that, The first heat exchange circuit includes: The first heat exchange tube and the second heat exchange tube, the two ends of the first heat exchange channel are respectively connected to the first heat exchange tube and the second heat exchange tube, the end of the first heat exchange tube away from the first heat exchange channel is connected to the inlet of the desorption tank (9), and the end of the second heat exchange tube away from the first heat exchange channel is connected to the outlet of the desorption tank (9). The fourth heat exchanger (10) has a seventh heat exchange channel and an eighth heat exchange channel that are independent of each other. The two ends of the eighth heat exchange channel are respectively connected to the outlet of the absorption device (3) and the inlet of the desorption tank (9). The fuel cell is also connected to a circulating water tank (11), the circulating water tank (11) is connected to a first pipe, and the water with a first preset temperature generated by the fuel cell is discharged from the first pipe; one end of the seventh heat exchange channel is connected to the first pipe, and the other end of the seventh heat exchange channel is connected to the circulating water tank (11) through a second pipe.

9. The ammonia cracking system according to claim 4, characterized in that, The ammonia cracking system also includes: The exhaust gas treatment device (12) is connected to the fourth heat exchange channel and is used to treat nitrogen oxides in the product system of the fourth heat exchange channel after heat exchange.

10. The ammonia cracking system according to claim 7, characterized in that, The ammonia cracking system also includes: A heating unit (13) is provided, which cooperates with the desorption container (9). The heating unit (13) is configured to be openable and closed, so as to heat the desorption container (9) by activating the heating unit (13).

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