Energy-saving ammonia hydrogen fuel cell system coupled with ammonia decomposition and power generation method

Abstract

The invention discloses an energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition and a power generation method. The energy-saving ammonia-hydrogen fuel cell system comprises a liquid ammonia tank, an ammonia decomposition reactor, a purification device, a buffer tank, a combustion mechanism and a fuel cell. The liquid ammonia tank is sequentially connected with the first ammonia decomposition reactor, the first purification device and the buffer tank, and the buffer tank is connected with the second purification device and the hydrogen using device; the first ammonia decomposition reactor is provided with an electric heating device, and the combustion mechanism is connected with a flue gas flow channel of the second ammonia decomposition reactor. An ammonia gas flow channel of the second ammonia decomposition reactor is connected with a third purification device; and the third purification device is connected with the fuel cell. The purification device is formed by connecting a plurality of adsorption columns in parallel, and control valves are arranged among the adsorption columns to adjust the gas flow direction. Electric heating and high-temperature flue gas heating are combined, ammonia gas is rapidly decomposed, desorption is conducted synchronously through decomposed gas, the desorbed gas is used for combustion heat supply, the starting time is shortened, efficiency is improved, energy self-circulation is achieved, external fuel dependence is reduced, and the hydrogen yield and the power generation efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ammonia-hydrogen fuel cell devices, and in particular to an energy-saving ammonia-hydrogen fuel cell system and power generation method that couple ammonia decomposition and recycle hydrogen-containing tail gas. Background Art

[0002] As a clean, efficient, and renewable energy carrier, hydrogen energy has received wide attention. However, problems such as high storage and transportation costs and poor safety of hydrogen restrict its large-scale application. Ammonia, as a hydrogen-rich compound, has advantages such as convenient storage and transportation, high energy density, and good safety, and is considered an ideal hydrogen energy carrier. In recent years, significant progress has been made in ammonia decomposition for hydrogen production technology, providing a new approach for hydrogen energy utilization. A fuel cell is a device that directly converts chemical energy into electrical energy, with advantages such as high energy conversion efficiency and low environmental pollution. Among them, proton exchange membrane fuel cells (PEMFCs) have broad application prospects in fields such as transportation and portable power sources due to their advantages of fast startup, high power density, and low operating temperature. However, PEMFCs have high requirements for hydrogen purity. Trace amounts of ammonia generated in traditional ammonia decomposition for hydrogen production processes will poison the fuel cell catalyst and reduce the battery performance; in actual application processes, the gas generated by ammonia decomposition needs to be effectively separated and purified before it can enter PEMFC for power generation; there is a large amount of energy consumption in both ammonia decomposition and decomposition and purification; the overall energy utilization rate is low. Summary of the Invention

[0003] Aiming at the defects in the ammonia-hydrogen fuel cell that couples ammonia decomposition reaction in the prior art, such as large energy consumption, low energy utilization rate, and low system hydrogen production and power generation efficiency, an energy-saving ammonia-hydrogen fuel cell system and power generation method that couple ammonia decomposition and can effectively utilize the gas and energy generated during the ammonia decomposition process and improve the fuel cell power generation efficiency are provided.

[0004] The technical solution adopted by the present invention to solve its technical problems is as follows: An energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition, comprising a liquid ammonia tank, a first ammonia decomposition reactor, a first purification device, a buffer tank, a second purification device, a combustion mechanism, a second ammonia decomposition reactor, a third purification device and a fuel cell; The liquid ammonia tank is connected in series with the first ammonia decomposition reactor, the first purification device and the buffer tank in sequence; The buffer tank is connected in series with the second purification device, and the second purification device is then connected with a hydrogen-using device; An electric heating device is arranged on the first ammonia decomposition reactor; The combustion mechanism includes a combustion device, a fuel storage tank and a fan; The outlet of the fuel storage tank and the fan are simultaneously connected to the combustion inlet of the combustion device; The second ammonia decomposition reactor includes a flue gas flow channel and an ammonia gas flow channel; The flue gas flow channel and the ammonia gas flow channel are arranged in a cross-fitting manner; The combustion outlet of the combustion device is connected to the flue gas inlet on the flue gas flow channel of the second ammonia decomposition reactor; The second decomposition gas outlet on the ammonia gas flow channel of the second ammonia decomposition reactor is connected to the third purification device; The third purification device is then connected to the fuel cell; The first purification device, the second purification device and the third purification device are all composed of at least two adsorption columns arranged in parallel, and a plurality of control valves are arranged between the plurality of adsorption columns, and the plurality of control valves are used to adjust the flow direction of the gas inside the purification device between the plurality of adsorption columns; One gas outlet of the first purification device, one gas outlet of the second purification device and one gas outlet of the third purification device are simultaneously connected to the fuel storage tank.

[0005] Further, a water bath heater, an ammonia gas buffer tank and an intermediate tank are sequentially arranged in series between the liquid ammonia tank and the first ammonia decomposition reactor. The liquid ammonia tank is directly connected to the intermediate tank, and a first valve is arranged between the liquid ammonia tank and the intermediate tank; The intermediate tank communicates with the ammonia gas flow channel of the second ammonia decomposition device.

[0006] Further, the purification device is formed by two adsorption columns arranged in parallel. The open ends of the two adsorption columns arranged in parallel are connected together, and control valves are arranged at the inlets of each adsorption column; The decomposition gas outlet ends of the two adsorption columns arranged in parallel are connected, and control valves are also arranged at the decomposition gas outlet ends of each adsorption column. An analysis gas outlet is respectively arranged on each adsorption column; A corresponding control valve is also arranged at each analysis gas outlet; When the control valve at the inlet of one adsorption column is opened, the control valve at the inlet of the other adsorption column remains closed, and the control valves at the decomposition gas outlet ends of the two adsorption columns are opened simultaneously; So that a part of the decomposed gas adsorbed by one adsorption column flows back into the interior of the adsorption column from the decomposition gas outlet end of the other adsorption column arranged in parallel.

[0007] Further, a heat exchanger is further included in the combustion mechanism. The fan is connected to the heat exchanger, and the heat exchanger is then connected to the combustion device; The heat exchanger is also connected to an oil removal and drying device at the same time, and the oil removal and drying device is then connected to the buffer tank.

[0008] Furthermore, the second ammonia decomposition reactor includes a main body, a second ammonia inlet, a plurality of ammonia connecting pipes, and a second decomposed gas outlet; the two ends of the main body are respectively fixed with a top plate and a bottom plate, and a plurality of flue gas connecting pipes and a plurality of ammonia connecting pipes are fixed on the top plate, and a plurality of flue gas connecting pipes and a plurality of ammonia connecting pipes are also fixed on the bottom plate; the main body includes a first sleeve, a second sleeve, a third sleeve, and a fourth sleeve sleeved from the inside to the outside in sequence; there is a first gap between the first sleeve and the second sleeve, a second gap between the second sleeve and the third sleeve, and a third gap between the third sleeve and the fourth sleeve; a plurality of partition plates are arranged in the first gap, and the plurality of partition plates divide the first gap into a plurality of first spaces with equal length and non-communication with each other; a plurality of partition plates are arranged in the second gap, and the plurality of partition plates divide the second gap into a plurality of second spaces with equal length and non-communication with each other, and a plurality of partition plates are arranged in the third gap, and the plurality of partition plates divide the third gap into a plurality of third spaces with equal length and non-communication with each other; four partition plates are also arranged inside the first sleeve; the four partition plates divide the inside of the first sleeve into fourth spaces with equal length but non-communication with each other; the second ammonia inlet communicates with one of the second spaces in the second gap, and the second decomposed gas outlet communicates with one of the fourth spaces inside the first sleeve; a plurality of ammonia connecting pipes are fixed above the second gap and above the first sleeve; a plurality of ammonia connecting pipes are also fixed below the second gap and below the first sleeve; the plurality of ammonia connecting pipes sequentially connect the plurality of second spaces and the plurality of fourth spaces; the second ammonia inlet, the plurality of ammonia connecting pipes, the plurality of second spaces, the plurality of fourth spaces, and the second decomposed gas outlet together form the ammonia flow path of the second ammonia decomposition reactor.

[0009] Furthermore, it further includes a plurality of flue gas connecting pipes, a flue gas inlet, and a flue gas outlet; the flue gas inlet is located below the main body and communicates with one of the third spaces, and the flue gas outlet is located above the main body and communicates with one of the first spaces; a plurality of flue gas connecting pipes are arranged above the first gap, and a plurality of flue gas connecting pipes are also arranged above the third gap; a plurality of flue gas connecting pipes are arranged below the first gap; a plurality of flue gas connecting pipes are also arranged below the third gap; the plurality of ammonia connecting pipes sequentially connect the plurality of first spaces and the plurality of third spaces; the flue gas inlet, the plurality of flue gas connecting pipes, the plurality of first spaces, the plurality of third spaces, and the flue gas outlet together form the flue gas flow path of the second ammonia decomposition reactor.

[0010] Further, it further includes a water circulation system, which includes a circulation water tank, a first water cooler, a water cooling device, a second water cooler, a third water cooler and a radiator; the circulation water tank is connected to the first water cooler, and the first water cooler is located between the first ammonia decomposition reactor and the first purification device and is respectively connected to the first ammonia decomposition reactor and the first purification device; the first water cooler is further sequentially connected to an intermediate tank and the water cooling device, and the water cooling device is respectively connected to a combustion mechanism and a buffer tank; the water cooling device is also connected to the circulation water tank; one inlet of the second water cooler is connected to the second decomposition gas outlet of the second ammonia decomposition reactor, the other inlet of the second water cooler is connected to the circulation water tank, one outlet of the second water cooler is connected to the third purification device, the other outlet of the second water cooler is connected to the third water cooler, and the flue gas flow path of the second ammonia decomposition reactor is also connected to the third water cooler; the third water cooler is further connected to a water bath heater, and the water bath heater is further communicated with the circulation water tank; a radiator is externally connected to the circulation water tank.

[0011] A power generation method for an energy-saving ammonia-hydrogen fuel cell system applying a coupled ammonia decomposition includes the following steps: Step 1: Introduce ammonia gas into the first ammonia decomposition reactor, and the first ammonia decomposition reactor decomposes part of the ammonia gas into a mixed gas of hydrogen and nitrogen; Step 2: Introduce the decomposed hydrogen and nitrogen from the first ammonia decomposition reactor into the first purification device for purification, and synchronously use part of the purified mixed gas containing hydrogen and nitrogen after passing through the first purification device to purge the first purification device; Introduce the remaining purified mixed gas containing hydrogen and nitrogen into the buffer tank; Step 3: Introduce the mixed gas containing hydrogen and nitrogen after purging the first purification device into the combustion mechanism for combustion; Generate high-temperature flue gas and introduce the generated high-temperature flue gas into the second ammonia decomposition reactor; Step 4: Introduce the mixed gas of hydrogen and nitrogen in the buffer tank into the second purification device for hydrogen purification, and at the same time, also use part of the purified hydrogen to synchronously purge the second purification device, and introduce the remaining purified hydrogen into the hydrogen-using device; Step 5: Introduce the hydrogen after purging the second purification device into the combustion mechanism for combustion and generate high-temperature flue gas, and introduce the generated high-temperature flue gas into the second ammonia decomposition reactor; At the same time, introduce ammonia gas into the second ammonia decomposition reactor; Step 6: The second ammonia decomposition reactor decomposes ammonia gas into a mixed gas of hydrogen and nitrogen; Introduce the generated mixed gas of hydrogen and nitrogen from the second ammonia decomposition reactor into the third purification device for purification; Synchronously use part of the purified mixed gas to purge the third purification device, and introduce the remaining purified mixed gas into the fuel cell to generate electric energy.

[0012] Further, in Step 5, when the hydrogen after purging the second purification device also enters the combustion mechanism for combustion and generates high-temperature flue gas and heats the second ammonia decomposition reactor, part of the ammonia gas discharged from the liquid ammonia tank and vaporized is shunted to the second ammonia decomposition reactor.

[0013] Further, in step six, the hydrogen and nitrogen after purging the third purification device are also introduced into the combustion mechanism for combustion to generate high-temperature flue gas.

[0014] An energy-saving ammonia-hydrogen fuel cell system and power generation method coupled with ammonia decomposition according to the present invention adopt an electrically heated ammonia decomposition reactor and a high-temperature flue gas heated ammonia decomposition reactor, and a purification device with multiple adsorption columns connected in parallel. The decomposition gas is used to synchronously desorb the purification device and the desorbed gas is burned, and the burned gas is used for heating the second ammonia decomposition reactor; during operation, the electrically heated ammonia decomposition reactor is first used to quickly decompose ammonia, so that ammonia is adsorbed in multiple purification devices inside the system and the desorption is carried out synchronously using the decomposition gas; then the decomposed gas discharged after desorption is used for combustion to provide heat for the high-temperature flue gas heated ammonia decomposition reactor; compared with the conventional high-temperature flue gas heated ammonia decomposition hydrogen production system, the system can quickly produce hydrogen and at the same time produce high-temperature flue gas for heating; the overall start-up time of the system is shortened and the operation efficiency of the system is improved; on this basis, combined with the water circulation system and the second ammonia decomposition reactor with a casing structure, it is beneficial to the effective transfer and reuse of heat among various components during the operation of the system; the demand and dependence on external fuel of the system are reduced, the energy self-circulation inside the system is realized and the recovery utilization rate is improved, and at the same time, the hydrogen production of the system and the subsequent fuel cell power generation efficiency are ensured.

[0015] In summary, the system has the following beneficial effects:

[0016] A It combines the processes of industrial hydrogen production systems such as ammonia supply, hydrogen production, and purification, and combines the recovery process to reduce energy consumption.

[0017] B The power consumption of the ammonia decomposition device in the traditional system is relatively large. Although a hydrogen recovery system is set up, the recovery rate of the system is limited, basically about 50-70%. Therefore, a self-heating ammonia decomposition reactor is set up to recover and supply heat for the non-fully recovered desorbed gas, reducing the power consumption of the system.

[0018] C The system also has an emergency power generation system, which plays a certain positive role in the standby power supply of the control system of the industrial system and improves the reliability of the control system. Description of the Drawings

[0019] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for the specific embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1Schematic structural diagram of an energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to the present invention;

[0021] Figure 2 Schematic structural diagram of the second ammonia decomposition reactor of an energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to the present invention;

[0022] Figure 3 Schematic diagram of the internal structure of the second ammonia decomposition reactor of an energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to the present invention;

[0023] Figure 4 Schematic diagram of the internal structure of the second ammonia decomposition reactor of an energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to the present invention from another angle. Detailed implementation manners

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] As Figures 1 to 4 shown, an energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to the present invention includes a liquid ammonia tank 1, a first ammonia decomposition reactor 2, a first purification device 3, a buffer tank 4, a second purification device 5, a combustion mechanism 6, a second ammonia decomposition reactor 7, a third purification device 8, and a fuel cell C;

[0026] The liquid ammonia tank 1 is connected in series with the first ammonia decomposition reactor 2, the first purification device 3, and the buffer tank 4 in sequence; the buffer tank 4 is connected in series with the second purification device 5, and the second purification device 5 is further connected to a hydrogen-using device;

[0027] The combustion mechanism 6 includes a combustion device 60, a fuel storage tank 61, and a blower 63; the outlet of the fuel storage tank 61 and the blower 63 are simultaneously connected to the combustion inlet of the combustion device 60; the second ammonia decomposition reactor 7 includes a flue gas flow channel and an ammonia gas flow channel; the flue gas flow channel and the ammonia gas flow channel are arranged in a cross-fitting manner; the combustion outlet of the combustion device 60 is connected to the flue gas inlet 74 on the flue gas flow channel of the second ammonia decomposition reactor;

[0028] The second decomposition gas outlet 73 on the ammonia gas flow channel of the second ammonia decomposition reactor is connected to the third purification device; the third purification device 8 is further connected to the fuel cell C;

[0029] The first purification device 3, the second purification device 5, and the third purification device 8 are each composed of at least two adsorption columns arranged in parallel. A plurality of control valves are provided between the plurality of adsorption columns, and the plurality of control valves are used to adjust the flow direction of the gas inside the purification device among the plurality of adsorption columns; One gas outlet of the first purification device 3, one gas outlet of the second purification device 5, and one gas outlet of the third purification device 8 are simultaneously connected to the fuel storage tank 61.

[0030] In Figure 1 it, a water bath heater 11, an ammonia buffer tank 12, and an intermediate tank 13 are successively arranged in series between the liquid ammonia tank 1 and the first ammonia decomposition reactor 2. The water bath heater 11 can heat the liquid ammonia introduced from the liquid ammonia tank 1 and cause the liquid ammonia to be initially vaporized to form ammonia gas. The generated ammonia gas first enters the ammonia buffer tank 12 for buffering and pressure adjustment and then enters the intermediate tank 13 for ammonia storage; In order to improve the system operation efficiency and reduce the system energy consumption; Preferably, the liquid ammonia tank 1 is directly connected to the intermediate tank 13 and a first valve is provided between the liquid ammonia tank 1 and the intermediate tank 13; That is, when the external temperature is high, the liquid ammonia in the liquid ammonia tank 1 can directly enter the intermediate tank 13 for evaporation and vaporization, reducing the heat loss caused by the heating of the electric heater 13 and effectively utilizing the ambient temperature for heating and liquefaction; The intermediate tank 13 is then connected to the first ammonia decomposition reactor 2; The first ammonia decomposition reactor 2 decomposes the ammonia gas introduced from the intermediate tank 13 to generate a mixed gas of hydrogen and nitrogen; Specifically, an electric heating device is provided on the first ammonia decomposition reactor 2, and the electric heating device is used to heat the first ammonia decomposition reactor 2 and promote the endothermic decomposition of the ammonia gas therein to generate hydrogen and nitrogen; The decomposed hydrogen and nitrogen then enter the first purification device 3 for adsorption to remove the residual unreacted ammonia gas in the mixed gas.

[0031] The first purification device 3 is formed by two adsorption columns arranged in parallel. The open ends of the two adsorption columns arranged in parallel are connected together, and control valves are provided at the inlets of each adsorption column to control the flow rate and flow direction of the gas entering each adsorption column. The decomposition gas outlet ends of the two adsorption columns arranged in parallel are connected, and control valves are also provided at the decomposition gas outlet ends of each adsorption column to control the flow rate and flow direction of the gas discharged from each adsorption column. Among them, desorbed gas outlets are respectively provided on each adsorption column, and corresponding control valves are also provided on each desorbed gas outlet. During operation, when the control valve at the inlet of one of the adsorption columns is opened, the control valve at the inlet of the other adsorption column remains closed, and the control valves at the decomposition gas outlet ends of the two adsorption columns are opened simultaneously. Part of the decomposed gas adsorbed by one of the adsorption columns flows back into the interior of the adsorption column from the decomposition gas outlet end of the other adsorption column arranged in parallel, realizing the purging effect of part of the decomposed gas on this adsorption column and achieving the desorption effect on this adsorption column. At the same time, the corresponding control valve at the desorbed gas outlet of this adsorption column is opened to discharge the purged decomposed gas from the first purification device 3. By correspondingly changing the opening of the control valves at the inlets of different adsorption columns and opening the control valve at the desorbed gas outlet of the other adsorption column, the two adsorption columns in the first purification device 3 can operate alternately and adsorb ammonia in the decomposed gas introduced from the first ammonia decomposition reactor 2, and at the same time, part of the decomposed gas can synchronously purge and desorb the other adsorption column, improving the operation efficiency of the first purification device 3. Part of the decomposed gas after purging and desorbing is discharged from the first purification device 3.

[0032] The purified decomposed gas discharged from the first purification device 3 enters the buffer tank 4 for buffering and pressure regulation. A primary compression device 41 is provided between the buffer tank 4 and the second purification device 5. The primary compression device 41 is used to further control the pressure of the gas discharged from the buffer tank 4 and entering the second purification device 5, so as to better improve the adsorption and purification effect of the second purification device 5. Among them, the second purification device 5 is a pressure swing adsorption device (PSA). The second purification device 5 is composed of two pressure swing adsorption columns arranged in parallel. The open ends of the two pressure swing adsorption columns arranged in parallel are connected together, and a control valve is provided at the inlet of each pressure swing adsorption column to control the flow rate and flow direction of the gas entering each pressure swing adsorption column. The decomposed gas outlet ends of the two pressure swing adsorption columns arranged in parallel are connected together, and a control valve is also provided at the outlet of each pressure swing adsorption column to control the flow rate and flow direction of the gas discharged from each adsorption column. Among them, a pressure swing desorbed gas outlet is respectively provided on each pressure swing adsorption column. A corresponding control valve is also provided at each pressure swing desorbed gas outlet. During operation, when the control valve at the inlet of one of the pressure swing adsorption columns is opened, the control valve at the inlet of the other pressure swing adsorption column remains closed, and the control valves at the decomposed gas outlet ends of the two pressure swing adsorption columns are opened simultaneously. So that part of the decomposed gas after adsorption by one of the pressure swing adsorption columns flows back into the interior of the pressure swing adsorption column from the decomposed gas outlet end of the other pressure swing adsorption column arranged in parallel, realizing the purging effect of part of the decomposed gas on this adsorption column and achieving the desorption effect on this pressure swing adsorption column. At the same time, the corresponding control valve at the desorbed gas outlet of this pressure swing adsorption column is opened to discharge the purged decomposed gas from the second purification device 5. By correspondingly changing the opening of the control valves at the inlets of different pressure swing adsorption columns and opening the control valve at the desorbed gas outlet of the other pressure swing adsorption column, the two pressure swing adsorption columns in the first purification device 3 can operate alternately and adsorb ammonia in the decomposed gas introduced from the first ammonia decomposition reactor 2. At the same time, part of the decomposed gas can synchronously purge and desorb the other pressure swing adsorption column. The operation efficiency of the first purification device 3 is improved. Part of the decomposed gas after purging and desorbing is discharged from the second purification device 5.

[0033] In Figure 1In the system, the decomposition gas outlet end of the second purification device 5 is successively connected to a secondary pressurization device A1, a hydrogen buffer tank A2, and the hydrogen-using device. The decomposition gas further purified by the second purification device 5 enters the hydrogen-using device for hydrogen application, such as a hydrogen refueling station, a fuel cell, etc., after the pressure adjustment by the secondary pressurization device A1 and the hydrogen buffer tank A2. Since the gas after being utilized by the hydrogen-using device contains many impurities, such as O2, N2, Ar, COX, oil mist, metal dust, etc., metal powder and part of the oil stain need to be removed by means of water washing, etc. Specifically, the tail gas containing hydrogen discharged after the operation of the hydrogen-using device enters a tail gas recovery buffer tank B1 connected to the tail gas end of the hydrogen-using device. The tail gas recovery buffer tank B1 can collect and separate the tail gas containing hydrogen, discharge the part of the tail gas without hydrogen after separation into the air, and discharge the remaining tail gas containing hydrogen and introduce it into a water washing and impurity removal device B2 connected thereto for water washing to remove various residual solid metal impurities therein. The water washing and impurity removal device B2 is further connected to a steam-water separation device B3. The steam-water separation device B3 cools the tail gas containing hydrogen after water washing, removes the residual liquid therein and discharges it. The steam-water separation device B3 is successively connected to a air supply mechanism B4 and an oxygen removal device B5 to remove the oxygen contained in the tail gas to reduce the risk of explosion during subsequent flow, especially during heat exchange, and improve the safety of the system operation process. Since heat is generated during the process of removing the oxygen contained in the tail gas, in order to utilize the heat generated during the system operation process at the same time, a heat exchanger 62 is further included in the combustion mechanism. The oxygen removal mechanism B5 is connected to the heat exchanger 62, the fan 63 is connected to the heat exchanger 62, and the heat exchanger 62 is further connected to a combustion device 60 in the combustion mechanism. The air discharged by the fan 63 enters the combustion device 60 after passing through the heat exchanger 62. The heat exchanger 62 can exchange heat between the heat of the gas discharged from the oxygen removal mechanism B5 and the air introduced from the fan 63, reducing the temperature of the hydrogen-containing tail gas after oxygen removal and increasing the heat of the air introduced from the fan 63 at the same time. It improves the combustion efficiency of the subsequent combustion device and is also beneficial to the subsequent storage and recycling of the hydrogen-containing tail gas. Preferably, the heat exchanger 62 is further connected to an oil removal and drying device 43, and the oil removal and drying device 43 is connected to the buffer tank 4, so that the hydrogen-containing gas after cooling and drying enters the buffer tank 4 to realize the recycling of the gas. More preferably, the air supply mechanism B4 is also communicated with the fuel storage tank 61, and an air supply valve is provided between the air supply mechanism B4 and the fuel storage tank 61. By adjusting the opening degree of the air supply valve, part of the hydrogen and nitrogen entering the heat exchanger 62 through the air supply mechanism B4 can enter the fuel storage tank 61 for storage to improve the combustion efficiency of the subsequent combustion device 60.

[0034] Among them, in order to improve the energy utilization rate of the system, realize the self-circulation of the fuel supply of the system and reduce the demand of the system for external fuel, the desorbed gas outlet of the first purification device 3 and the desorbed gas outlet of the second purification device 5 are simultaneously connected to the fuel storage tank 61; part of the hydrogen and nitrogen used for purging generated during the online desorption processes of the first purification device 3 and the second purification device 5; and the desorbed ammonia; can simultaneously enter the fuel storage tank 61 to be used as fuel for subsequent combustion; realizing the self-circulation supply of the combustion fuel of the system, improving the energy utilization rate of the system and reducing the energy consumption of the system; the fuel stored in the fuel storage tank 61, that is, the hydrogen and nitrogen after purge desorption and the desorbed ammonia, and the air introduced from the fan 63 and heat-exchanged by the heat exchanger 62, enter the combustion device 60 for mixed combustion to generate high-temperature flue gas; the combustion device 60 is connected to the flue gas inlet 74 of the second ammonia decomposition reactor 7; providing a heat source for the ammonia decomposition in the second ammonia decomposition reactor 7.

[0035] Such as Figures 2 to 4As shown, the second ammonia decomposition reactor 7 includes a main body 70, a second ammonia inlet 71, a plurality of ammonia connecting pipes 72, a second decomposed gas outlet 73, a flue gas inlet 74, a plurality of flue gas connecting pipes 75, and a flue gas outlet 76. The main body 70 is of a cylindrical structure, with a top plate 77 and a bottom plate 78 fixed at both ends of the main body 70 respectively. A plurality of the flue gas connecting pipes 75 and a plurality of the ammonia connecting pipes 72 are fixed on the top plate 77, and a plurality of the flue gas connecting pipes 75 and a plurality of the ammonia connecting pipes 72 are also fixed on the bottom plate 78. The main body 70 includes a first sleeve 704, a second sleeve 703, a third sleeve 702, and a fourth sleeve 701 which are sleeved from the inside to the outside in sequence. There are gaps between adjacent two sleeves and the gaps between any adjacent two sleeves are equal to each other. A plurality of partition plates 705 are evenly fixed between adjacent two sleeves, and the plurality of partition plates 705 divide the gap between adjacent two sleeves into a plurality of spaces with equal lengths and not communicating with each other. There is a first gap between the first sleeve 704 and the second sleeve 703, a second gap between the second sleeve 703 and the third sleeve 702, and a third gap between the third sleeve 702 and the fourth sleeve 701. A plurality of partition plates 705 are arranged in the first gap, and the plurality of partition plates 705 divide the first gap into a plurality of first spaces with equal lengths and not communicating with each other. A plurality of partition plates 705 are arranged in the second gap, and the plurality of partition plates 705 divide the second gap into a plurality of second spaces with equal lengths and not communicating with each other. A plurality of partition plates 705 are arranged in the third gap, and the plurality of partition plates 705 divide the third gap into a plurality of third spaces with equal lengths and not communicating with each other. Four partition plates 705 are also arranged inside the first sleeve 704. The four partition plates 705 divide the inside of the first sleeve 407 into a plurality of fourth spaces with equal lengths but not communicating with each other. The second ammonia inlet 71 and the second decomposed gas outlet 73 are both located at the same end of the main body 70. The second ammonia inlet 71 communicates with one of the second spaces in the second gap, and the second decomposed gas outlet 73 communicates with one of the fourth spaces inside the first sleeve 704. A plurality of ammonia connecting pipes 72 are also fixed on the same end of the main body 70 as the second ammonia inlet 71. Specifically, the ammonia connecting pipes 72 are of a bent structure. A plurality of ammonia connecting pipes 72 are fixed above the second gap and above the first sleeve 704. Each ammonia connecting pipe 72 located above the second gap has two ends communicating with different second spaces respectively, and two ends of one of the ammonia connecting pipes 72 communicate with a second space and a fourth space respectively. Each ammonia connecting pipe 72 located above the first sleeve 704 has two ends communicating with different fourth spaces respectively.

[0036] Similarly, a plurality of ammonia connecting pipes 72 are also fixed below the second gap and below the first sleeve 704. Both ends of each ammonia connecting pipe 72 located below the second gap communicate with different second spaces respectively. Both ends of each ammonia connecting pipe 72 located above the first sleeve 704 communicate with different fourth spaces respectively. One end of one of the ammonia connecting pipes 72 is connected to the second decomposition gas outlet 73 through the fourth space. After ammonia enters the second space in the second gap through the second ammonia inlet 71, it flows along the extension direction of the second space and enters another second space through one of the ammonia connecting pipes 72 below the body 70. Subsequently, it continues to flow in this second space and enters another second space again through another connected ammonia connecting pipe 72 above the body 70. Ammonia thus flows up and down in a plurality of second spaces, flows through a plurality of the second spaces, and finally enters the interior of the first sleeve 704 through the ammonia connecting pipe 72 that is simultaneously connected to the second space and the fourth space. Then, it flows up and down in sequence in a plurality of fourth spaces in the first sleeve 704 and finally is discharged through the second decomposition gas outlet 73 on the same side as the second ammonia inlet 71. The second ammonia inlet 71, the plurality of ammonia connecting pipes 72, the plurality of second spaces, the plurality of fourth spaces, and the second decomposition gas outlet 73 together form the ammonia flow path of the second ammonia decomposition reactor;

[0037] Similarly, the flue gas inlet 74 is located below the body 70, and the flue gas inlet 74 is connected to the interior of the first sleeve 704. Specifically, a plurality of the flue gas connecting pipes 75 are also provided above the body 70, and a plurality of the flue gas connecting pipes 75 are provided above the first gap. Both ends of each flue gas connecting pipe 75 are respectively connected to adjacent and non - communicating first spaces; A plurality of the flue gas connecting pipes 75 are also provided above the third gap. Both ends of each flue gas connecting pipe 75 are respectively connected to adjacent and non - communicating third spaces; Both ends of one of the flue gas connecting pipes 75 are respectively communicated with the interior of the first sleeve 704 and one of the first spaces; Both ends of one of the flue gas connecting pipes are respectively communicated with the first space and the third space; Similarly, a plurality of the flue gas connecting pipes 75 are provided below the first gap. Both ends of each flue gas connecting pipe 75 are respectively connected to adjacent and non - communicating first spaces; A plurality of the flue gas connecting pipes 75 are also provided below the third gap. Both ends of each flue gas connecting pipe 75 are respectively connected to adjacent and non - communicating third spaces; One of the third spaces is communicated with the flue gas outlet 76. The flue gas outlet 76, the second ammonia inlet 71, and the second decomposition gas outlet 73 are located on the same side of the body 70; The flue gas outlet 76 and the flue gas inlet 74 are respectively located on opposite sides of the body 70; When the high - temperature flue gas enters the interior of the first sleeve 704 through the flue gas inlet 74, the high - temperature flue gas flows along the extending direction of the first sleeve 704 and is discharged through the flue gas connecting pipe 75 connected to the first sleeve 704 and enters the first space communicated therewith. Subsequently, it flows up and down in a plurality of adjacent first spaces in sequence, and enters the third space through the flue gas connecting pipe 75 connected to the first space and the third space. Then, it flows up and down in a plurality of adjacent third spaces in sequence and is discharged through the flue gas outlet 76; The flue gas inlet 74, the plurality of flue gas connecting pipes 75, the plurality of first spaces, the plurality of third spaces, and the flue gas outlet 76 together form the flue gas flow path of the second ammonia decomposition reactor 7.

[0038] In summary, the high-temperature flue gas flows spirally outward from the flue gas inlet 74 at the center of the main body 70 and finally discharges through the flue gas outlet 76 located on the outer periphery of the main body 70; while ammonia enters through the second ammonia inlet 71 located in the middle of the main body 70, flows towards the center close to the main body 70 and finally discharges through the second decomposition gas outlet 73 close to the center of the main body 70; due to the interval arrangement of the first sleeve 704, the second sleeve 703, the third sleeve 702 and the fourth sleeve 701, the heat of the high-temperature flue gas can be fully transferred to ammonia through the corresponding pipe walls during the respective flows of the high-temperature flue gas and ammonia, achieving sufficient heating of ammonia and promoting the endothermic decomposition of ammonia; wherein the flow directions of ammonia and the high-temperature flue gas are opposite, which is beneficial to the heat exchange between ammonia and the high-temperature flue gas; through the above-mentioned sleeve structure, combined with the partitions between multiple sleeves, multiple ammonia connecting pipes 72 and multiple flue gas connecting pipes 75; the flow path length is greatly increased within a limited space, the heat exchange area is increased, the flue gas and ammonia exchange heat in a staggered manner, and the heat exchange efficiency is improved; wherein the high-temperature flue gas inlet with a high temperature is arranged in the center, and the lower-temperature flue gas outlet after heat exchange is arranged in the outer circle, thereby improving the overall heat exchange effect of the reactor, reducing the heat dissipation and improving the energy utilization rate.

[0039] Wherein, the second ammonia inlet 71 communicates with the intermediate tank 13, and an ammonia valve is provided between the second ammonia inlet 71 and the intermediate tank 13. By adjusting the ammonia valve, part of the ammonia discharged from the intermediate tank 13 can be shunted into the second ammonia inlet 71 for the ammonia decomposition in the second ammonia decomposition reactor 7.

[0040] In order to further improve the temperature control efficiency of the system, enable the heat during the operation of the system to be quickly transferred between components, and improve the operation efficiency of the system; preferably, the energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition further includes a water circulation system 9, and the water circulation system 9 includes a circulation water tank 90, a first water cooler 91, a water cooling device 92, a second water cooler 93, a third water cooler 94 and a radiator 95. Cooling water is stored in the circulation water tank 91. The circulation water tank 90 is connected to the first water cooler 91. The first water cooler 91 is located between the first ammonia decomposition reactor 2 and the first purification device 3. The first water cooler 91 is used to cool the decomposition gas discharged from the first ammonia decomposition reactor 2. The first water cooler 91 is sequentially connected to the intermediate tank 13 and the water cooling device 92. The liquid water heated due to cooling the decomposition gas in the first water cooler 91 is introduced into the intermediate tank 13 to utilize its remaining heat to continue evaporating and heating the liquid ammonia in the intermediate tank 13, promoting the endothermic evaporation of the liquid ammonia to generate ammonia gas. The liquid water cooled after heating then enters the water cooling device 92. The water cooling device 92 is connected to the heat exchanger 62 and the oil removal and drying device 43. The water cooling device 92 is used to cool the hydrogen-containing tail gas discharged from the heat exchanger 62 after heat exchange with air and deoxidation. The cooled hydrogen-containing tail gas then enters the oil removal and drying device 43 for oil removal and drying, and then enters the buffer tank 4 for gas recycling. The water cooling device 92 is further connected to the circulation water tank 90. The remaining liquid water cooled in the water cooling device 92 can flow back to the circulation water tank 90 as a supplement to the liquid water in the circulation water tank 90. One inlet of the second water cooler 93 is connected to the second decomposition gas outlet 73 of the second ammonia decomposition reactor 7, and the other inlet of the second water cooler 93 is connected to the circulation water tank 90. One outlet of the second water cooler 93 is connected to the third purification device 8, and the other outlet of the second water cooler 93 is connected to the third water cooler 94. The second water cooler 93 is used to cool the decomposition gas discharged from the second ammonia decomposition reactor 7 to better suit the subsequent power generation of the fuel cell C and the adsorption and separation of ammonia gas by the purification device 8.

[0041] The third purification device 8 is formed by two adsorption columns arranged in parallel. The open ends of the two adsorption columns arranged in parallel are connected together, and control valves are provided at the inlets of each adsorption column to control the flow rate and flow direction of the gas entering each adsorption column; the decomposition gas outlet ends of the two adsorption columns arranged in parallel are connected together, and control valves are also provided at the outlets of each adsorption column to control the flow rate and flow direction of the gas discharged from each adsorption column; wherein, desorbed gas outlets are respectively provided on each adsorption column; corresponding control valves are also provided on each desorbed gas outlet; during operation, when the control valve at the inlet of one of the adsorption columns is opened, the control valve at the inlet of the other adsorption column remains closed, and the control valves at the decomposition gas outlet ends of the two adsorption columns are opened simultaneously; so that part of the decomposed gas after being adsorbed by one adsorption column flows back into the interior of the adsorption column from the decomposition gas outlet end of the other adsorption column arranged in parallel, realizing the purging effect of part of the decomposed gas on the adsorption column and achieving the desorption effect on the adsorption column; at the same time, the corresponding control valve at the desorbed gas outlet of this adsorption column is opened to discharge the decomposed gas after purging from the third purification device 8; by correspondingly changing the opening of the control valves at the inlets of different adsorption columns and opening the control valve at the desorbed gas outlet of the other adsorption column, the two adsorption columns in the third purification device 8 can operate alternately and adsorb ammonia in the decomposed gas introduced from the second ammonia decomposition reactor 7, and at the same time, part of the decomposed gas can synchronously purge and desorb the other adsorption column; improving the operating efficiency of the third purification device 8; part of the decomposed gas after purging and desorbing is discharged from the third purification device 8; preferably, the decomposition gas outlet end of the third purification device 8 is also connected to the buffer tank 4, and part of the hydrogen and nitrogen after adsorption and purification enter the buffer tank 4 to provide fuel for the hydrogen-consuming device, the desorbed gas outlet of the third purification device 8 communicates with the fuel storage tank 61, and the remaining hydrogen and nitrogen generated during the purging and desorbing process of the third purification device 8 are stored in the fuel storage tank 61 and can be used for subsequent combustion by the combustion device 60 to provide greater heat for the second ammonia decomposition reactor 7 to heat ammonia; while improving the system operating efficiency, realizing the self-circulation of the gas inside the system, and further reducing the demand and use of external fuel by the system.

[0042] The second water cooler 93 is connected to the third water cooler 94, and the flue gas outlet 76 of the second ammonia decomposition reactor 7 is also connected to the third water cooler 94. The liquid water that is heated by exchanging heat with the hydrogen and nitrogen discharged from the second ammonia decomposition reactor 7 in the second water cooler 93 is discharged from the second water cooler 93 and enters the third water cooler 94, where it further exchanges heat with the high-temperature flue gas discharged from the second ammonia decomposition reactor 7 to reduce the heat of the high-temperature flue gas so that the flue gas can be safely discharged into the air, improving the safety during the operation of the system; more preferably, the third water cooler 94 is further connected to the water bath heater 11. The liquid water that is heated again after exchanging heat with the high-temperature flue gas in the third water cooler 94 can enter the water bath heater 11 and serve as the heat source of the water bath heater 11 to heat the liquid ammonia, promoting the effective evaporation and vaporization of the liquid ammonia; further improving the energy cycle and recycling rate in the system; the water bath heater 11 is further connected to the circulation water tank 90 to introduce the remaining liquid water after heating into the circulation water tank 90, realizing the circulating flow of the liquid water in the entire system.

[0043] In order to better control the temperature of the liquid water flowing in the system and better cool or heat the components or gases; preferably, a radiator 95 is externally connected to the circulation water tank 90. The radiator 95 is used to dissipate heat and cool the liquid water in the circulation water tank 90, making it more suitable for the first water cooler 91 to cool the decomposed gas.

[0044] This application also discloses a power generation method using the energy-saving ammonia-hydrogen fuel cell system with coupled ammonia decomposition, including the following steps:

[0045] Step 1: Introduce ammonia gas into the first ammonia decomposition reactor, and the first ammonia decomposition reactor decomposes part of the ammonia gas into a mixed gas of hydrogen and nitrogen.

[0046] Step 2: Introduce the hydrogen and nitrogen decomposed by the first ammonia decomposition reactor into the first purification device for purification. Part of the mixed gas containing hydrogen and nitrogen after being purified by the first purification device is synchronously used to purge the first purification device; the remaining mixed gas containing hydrogen and nitrogen after being purified by the first purification device is introduced into the buffer tank.

[0047] Step 3: Introduce the mixed gas containing hydrogen and nitrogen after purging the first purification device into the combustion mechanism for combustion; generate high-temperature flue gas and introduce the generated high-temperature flue gas into the second ammonia decomposition reactor.

[0048] Step 4: Introduce the mixed gas of hydrogen and nitrogen in the buffer tank into the second purification device for hydrogen purification. At the same time, part of the purified hydrogen is also synchronously used to purge the second purification device, and the remaining purified hydrogen is introduced into the hydrogen-using device.

[0049] Step Five: Introduce the hydrogen gas after purging the second purification device into the combustion mechanism for combustion to generate high-temperature flue gas, and introduce the generated high-temperature flue gas into the second ammonia decomposition reactor; at the same time, introduce ammonia gas into the second ammonia decomposition reactor.

[0050] Step Six: The second ammonia decomposition reactor decomposes ammonia gas into a mixed gas of hydrogen and nitrogen; introduce the mixed gas of hydrogen and nitrogen generated by the second ammonia decomposition reactor into the third purification device for purification; synchronously use part of the purified mixed gas to purge the third purification device, and introduce the remaining purified mixed gas into the fuel cell to generate electric energy.

[0051] In Step One, in order to increase the adsorption amount of ammonia gas in the subsequent first purification device and second purification device, the usage amounts of hydrogen and nitrogen for purging ammonia gas in the first purification device and second purification device are increased; so that more hydrogen and nitrogen can be used for subsequent combustion, which is beneficial for the rapid and effective combustion of the combustion mechanism to generate high-temperature flue gas, thereby heating the second ammonia decomposition reactor; in Step Five, when the hydrogen gas after purging the second purification device also enters the combustion mechanism for combustion to generate high-temperature flue gas and further heats the second ammonia decomposition reactor, part of the ammonia gas discharged from the liquid ammonia tank and vaporized is diverted to the second ammonia decomposition reactor, reducing the usage amount of ammonia gas entering the first ammonia decomposition reactor; reducing the consumption of external power supply by the system; in Step Six, introduce the hydrogen and nitrogen after purging the third purification device into the combustion mechanism for combustion to generate high-temperature flue gas, further increasing the heating of the second ammonia decomposition reactor to promote the ammonia decomposition efficiency therein.

[0052] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. An energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition, comprising a liquid ammonia tank, a first ammonia decomposition reactor, a first purification device, a buffer tank, a second purification device, a combustion mechanism, a second ammonia decomposition reactor, a third purification device and a fuel cell; The liquid ammonia tank is connected in series with the first ammonia decomposition reactor, the first purification device and the buffer tank in sequence; the buffer tank is connected in series with the second purification device, and the second purification device is further connected with a hydrogen-using device; an electric heating device is arranged on the first ammonia decomposition reactor; The combustion mechanism includes a combustion device, a fuel storage tank and a blower; the outlet of the fuel storage tank and the blower are simultaneously connected to the combustion inlet of the combustion device; the second ammonia decomposition reactor includes a flue gas flow channel and an ammonia gas flow channel; the flue gas flow channel and the ammonia gas flow channel are arranged in cross-fitting; the combustion outlet of the combustion device is connected to the flue gas inlet on the flue gas flow channel of the second ammonia decomposition reactor; The second decomposition gas outlet on the ammonia gas flow channel of the second ammonia decomposition reactor is connected to the third purification device; the third purification device is further connected to the fuel cell; The first purification device, the second purification device and the third purification device are each composed of at least two adsorption columns arranged in parallel, and a plurality of control valves are arranged between the plurality of adsorption columns, and the plurality of control valves are used to adjust the flow direction of the gas inside the purification device between the plurality of adsorption columns; one gas outlet of the first purification device, one gas outlet of the second purification device and one gas outlet of the third purification device are simultaneously connected to the fuel storage tank.

2. An energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to claim 1; characterized in that: A water bath heater, an ammonia gas buffer tank and an intermediate tank are sequentially arranged in series between the liquid ammonia tank and the first ammonia decomposition reactor, the liquid ammonia tank is directly communicated with the intermediate tank and a first valve is arranged between the liquid ammonia tank and the intermediate tank; the intermediate tank communicates with the ammonia gas flow channel of the second ammonia decomposition device.

3. An energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to claim 1, characterized in that: The purification device is formed by two adsorption columns arranged in parallel, the open ends of the two adsorption columns arranged in parallel are connected together and control valves are arranged at the inlets of each adsorption column; the decomposition gas outlet ends of the two adsorption columns arranged in parallel are connected and control valves are also arranged at the decomposition gas outlet ends of each adsorption column, and desorbed gas outlets are respectively arranged on each adsorption column; corresponding control valves are also arranged at each desorbed gas outlet; When the control valve at the inlet of one of the adsorption columns is opened, the control valve at the inlet of the other adsorption column remains closed, and the control valves at the decomposition gas outlet ends of the two adsorption columns are opened simultaneously; so that a part of the decomposed gas adsorbed by one of the adsorption columns flows back into the interior of the adsorption column from the decomposition gas outlet end of the other adsorption column arranged in parallel.

4. An energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to claim 1, characterized in that: The combustion mechanism further includes a heat exchanger, the blower is connected to the heat exchanger, and the heat exchanger is further connected to the combustion device; the heat exchanger is also connected to an oil removal and drying device, and the oil removal and drying device is further connected to the buffer tank.

5. An energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to claim 1, wherein: The second ammonia decomposition reactor includes a main body, a second ammonia inlet, a plurality of ammonia connecting pipes, and a second decomposed gas outlet; the two ends of the main body are respectively fixed with a top plate and a bottom plate, and a plurality of the flue gas connecting pipes and a plurality of the ammonia connecting pipes are fixed on the top plate, and a plurality of the flue gas connecting pipes and a plurality of the ammonia connecting pipes are also fixed on the bottom plate; the main body includes a first sleeve, a second sleeve, a third sleeve, and a fourth sleeve which are sleeved from the inside to the outside in sequence; There is a first gap between the first sleeve and the second sleeve, a second gap between the second sleeve and the third sleeve, and a third gap between the third sleeve and the fourth sleeve; a plurality of partition plates are arranged in the first gap, and the plurality of partition plates divide the first gap into a plurality of first spaces with equal lengths and not communicating with each other; a plurality of partition plates are arranged in the second gap, and the plurality of partition plates divide the second gap into a plurality of second spaces with equal lengths and not communicating with each other, and a plurality of partition plates are arranged in the third gap, and the plurality of partition plates divide the third gap into a plurality of third spaces with equal lengths and not communicating with each other; four partition plates are also arranged inside the first sleeve; the four partition plates divide the inside of the first sleeve into fourth spaces with equal lengths but not communicating with each other; The second ammonia inlet communicates with one of the second spaces in the second gap, and the second decomposed gas outlet communicates with one of the fourth spaces inside the first sleeve; a plurality of ammonia connecting pipes are fixed above the second gap and above the first sleeve; a plurality of ammonia connecting pipes are also fixed below the second gap and below the first sleeve; The plurality of ammonia connecting pipes sequentially connect the plurality of second spaces and the plurality of fourth spaces; the second ammonia inlet, the plurality of ammonia connecting pipes, the plurality of second spaces, the plurality of fourth spaces, and the second decomposed gas outlet together form the ammonia flow path of the second ammonia decomposition reactor.

6. An energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to claim 5, characterized in that: It further includes a plurality of flue gas connecting pipes, a flue gas inlet, and a flue gas outlet; the flue gas inlet is located below the main body and communicates with one of the third spaces, and the flue gas outlet is located above the main body and communicates with one of the first spaces; A plurality of the flue gas connecting pipes are arranged above the first gap, and a plurality of the flue gas connecting pipes are also arranged above the third gap; A plurality of the flue gas connecting pipes are arranged below the first gap; A plurality of the flue gas connecting pipes are also arranged below the third gap; The plurality of ammonia connecting pipes sequentially connect the plurality of first spaces and the plurality of third spaces; the flue gas inlet, the plurality of flue gas connecting pipes, the plurality of first spaces, the plurality of third spaces, and the flue gas outlet together form the flue gas flow path of the second ammonia decomposition reactor.

7. An energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to claim 2, characterized in that: It further includes a water circulation system, which comprises a circulation water tank, a first water cooler, a water cooling device, a second water cooler, a third water cooler and a radiator; the circulation water tank is connected to the first water cooler, and the first water cooler is located between the first ammonia decomposition reactor and the first purification device and is respectively connected to the first ammonia decomposition reactor and the first purification device; the first water cooler is further sequentially connected to the intermediate tank and the water cooling device, and the water cooling device is respectively connected to the combustion mechanism and the buffer tank; the water cooling device is also connected to the circulation water tank; One inlet of the second water cooler is connected to the second decomposition gas outlet of the second ammonia decomposition reactor, another inlet of the second water cooler is connected to the circulation water tank, one outlet of the second water cooler is connected to the third purification device, and another outlet of the second water cooler is connected to the third water cooler, The flue gas flow path of the second ammonia decomposition reactor is also connected to the third water cooler; the third water cooler is further connected to the water bath heater, and the water bath heater is further communicated with the circulation water tank; a radiator is externally connected to the circulation water tank.

8. A power generation method for an energy-saving ammonia-hydrogen fuel cell system coupled with ammonia decomposition according to any one of claims 1 to 7, characterized in that: It includes the following steps: Step 1: Introduce ammonia gas into the first ammonia decomposition reactor, and the first ammonia decomposition reactor decomposes part of the ammonia gas into a mixed gas of hydrogen and nitrogen; Step 2: Introduce the hydrogen and nitrogen decomposed by the first ammonia decomposition reactor into the first purification device for purification, and synchronously use part of the purified mixed gas containing hydrogen and nitrogen to purge the first purification device; introduce the remaining purified mixed gas containing hydrogen and nitrogen into the buffer tank; Step 3: Introduce the mixed gas containing hydrogen and nitrogen after purging the first purification device into the combustion mechanism for combustion; generate high-temperature flue gas and introduce the generated high-temperature flue gas into the second ammonia decomposition reactor; Step 4: Introduce the mixed gas of hydrogen and nitrogen in the buffer tank into the second purification device for hydrogen purification, and also synchronously use part of the purified hydrogen to purge the second purification device, and introduce the remaining purified hydrogen into the hydrogen-using device; Step 5: Also introduce the hydrogen after purging the second purification device into the combustion mechanism for combustion and generate high-temperature flue gas, and introduce the generated high-temperature flue gas into the second ammonia decomposition reactor; at the same time, introduce ammonia gas into the second ammonia decomposition reactor; Step 6: The second ammonia decomposition reactor decomposes ammonia gas into a mixed gas of hydrogen and nitrogen; introduce the mixed gas of hydrogen and nitrogen generated by the second ammonia decomposition reactor into the third purification device for purification; synchronously use part of the purified mixed gas to purge the third purification device, and introduce the remaining purified mixed gas into the fuel cell to generate electric energy.

9. A power generation method according to claim 8, characterized in that: In Step 5, when the hydrogen after purging the second purification device also enters the combustion mechanism for combustion and generates high-temperature flue gas and heats the second ammonia decomposition reactor, part of the ammonia gas discharged from the liquid ammonia tank and vaporized is shunted to the second ammonia decomposition reactor.

10. A power generation method according to claim 8, characterized in that: In step six, the hydrogen and nitrogen after purging the third purification device are also introduced into the combustion mechanism for combustion to generate high-temperature flue gas.

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