Vehicle-mounted ammonia cracking hydrogen production system of ammonia engine, and thermal management method therefor

Abstract

The present application relates to a vehicle-mounted ammonia cracking hydrogen production system of an ammonia engine, and a thermal management method therefor. The system comprises a liquid ammonia storage tank, a liquid ammonia gasification preheating tank, a hydrogen generation pipeline, a cracking gas storage pipeline, an ammonia-hydrogen inlet channel premixing pipe, an ammonia oxidizer heat production pipeline, an air conveying pipeline and a tail gas conveying pipeline. The heat of the ammonia oxidizer heat production pipeline not only provides heat for ammonia cracking, but also preheats ammonia required by ammonia cracking; the ammonia required by the ammonia oxidizer heat production pipeline is preheated, and heat is jointly supplied to a post-treatment system in cooperation with tail gas heat of an engine; the molar ratio of the supply amount of ammonia to that of air is adjusted according to the use conditions of the engine, so as to change the heat release of the ammonia oxidizer heat production pipeline, and the reaction is performed in the most appropriate reaction equation, thereby avoiding the generation of tail gas pollutants; in addition, the heat with the ammonia oxidizer heat production pipeline as a core is distributed and managed.

Description

Field of the Application The present application relates to the field of energy-saving and new energy vehicle technology, and in particular to a vehicle-mounted ammonia cracking hydrogen production system of an ammonia engine, and a thermal management method therefor. Background of the Application The fuel system of an ammonia-fueled compression ignition internal combustion engine is divided into: a) Mode: Ammonia gas + diesel co-combustion, no hydrogen gas required. b) Mode: Ammonia gas+ hydrogen co-combustion, with ammonia gas sourced from the vehicle-mounted liquid ammonia storage tank. The source of the hydrogen gas is the vehicle-mounted hydrogen storage tank and the vehicle-mounted ammonia cracking hydrogen production system. As the reverse reaction of synthetic ammonia, thermal cracking of ammonia is an endothermic reaction, and the conversion rate of ammonia is subject to thermodynamic limitations under certain conditions. At 450°C, the thermodynamic equilibrium conversion rate of the ammonia cracking reaction is above 99%. However, due to the reaction kinetic limitations under actual conditions, when equipped with a catalyst, the vehicle-mounted cracking can only achieve a 99% conversion through increasing the reaction environment temperature to 600°C. Taking into account the heat loss in the heat exchange process, the temperature of the hot flue gas, which serves as the thermal source for the ammonia cracking reaction, is required to be above 650°C. In the prior art, the hot flue gas comes from: 1) tail gas from the exhaust pipe, which has the disadvantage that the tail gas temperature is relatively low, and under most working conditions, the tail gas temperature cannot reach 650°C; 2) Electric heating, which has the advantage of simple control, but has the disadvantage of low heating power density and high cost; and 3) Heat produced from an ammonia oxidation reactor, which has the advantage of a high heat power density, but the disadvantage is that the heat production is difficult to control, and the reaction produces NOx and N2O, which worsens the overall vehicle exhaust emissions. Therefore, in view of die above disadvantages of hot flue gas sources, a thermal management method for an ammonia internal combustion engine ammonia cracking hydrogen production system is provided, which can solve the thermal management problem centered on the ammonia oxidation reactor. Summary of the Application The embodiment of the present application provides a vehicle-mounted ammonia cracking hydrogen production system of an ammonia engine, and a thermal management method therefor, so as to solve the problem in the related art that the heat production of the ammonia oxidation reactor is difficult to control, and the reaction produces NOx and N2O, which worsens the overall vehicle exhaust emissions. In a first aspect, a vehicle-mounted ammonia cracking hydrogen production system of an ammonia engine is provided, comprising: a liquid ammonia storage tank and a liquid ammonia gasification preheating tank connected successively; a gas outlet end of the liquid ammonia gasification preheating tank is connected to a first ammonia conveying pipe, a second ammonia conveying pipe, a third ammonia conveying pipe and a fourth ammonia conveying pipe; a hydrogen generation pipeline, a gas inlet end of which is connected to the first ammonia conveying pipe, and a gas outlet end of which is connected to an ammonia-hydrogen inlet channel premixing pipe through a cracking gas storage pipeline; the ammonia-hydrogen inlet channel premixing pipe is further connected to the second ammonia conveying pipe; an ammonia oxidizer heat production pipeline, which is connected to the third ammonia conveying pipeline and is configured to supply heat to the hydrogen generation pipeline; the ammonia oxidizer heat production pipeline is connected to a first hydrogen oxidation hot gas pipeline and a second hydrogen oxidation hot gas pipeline; and the first hydrogen oxidation hot gas pipeline is configured to preheat ammonia gas in the first ammonia conveying pipe; an air conveying pipeline, which is configured to supply oxygen gas to the ammonia-hydrogen inlet channel premixing pipe and the ammonia oxidizer heat production pipeline, and to control the oxygen conveying amount; a tail gas conveying pipeline, which comprises a first tail gas branch and a second tail gas branch; the second tail gas branch is configured to preheat the ammonia gas in the third ammonia conveying pipeline; and the first tail gas branch is configured to be connected to an gas inlet of a tail gas after-treatment system, and the second hydrogen oxidation hot gas pipeline and the fourth ammonia conveying pipe are also configured to be connected to the gas inlet of the tail gas after-treatment system. In some embodiments, the liquid ammonia gasification preheating tank comprises a primary preheating chamber and a secondary preheating chamber which are communicated with each other; the primary preheating chamber communicates with the second tail gas branch, and is connected to the third ammonia conveying pipe and the second ammonia conveying pipe; and the secondary preheating chamber is connected to the first ammonia conveying pipe and the fourth ammonia conveying pipe, and the first hydrogen oxidation hot gas pipeline communicates with the secondary preheating chamber. In some embodiments, the hydrogen generation pipeline comprises a first stop valve, an ammonia cracker, a cracking gas collection pipe, and a second stop valve which are connected successively; the ammonia oxidizer heat production pipeline comprises a third stop valve, an ammonia oxidizer and a gas outlet pipe which are connected successively; and heat is exchanged between the ammonia oxidizer and the ammonia cracker by means of a heat exchanger. In some embodiments, the cracking gas storage pipeline comprises a mixed gas buffer tank, a hydrogen flow meter and a sixth stop valve which are connected successively. In some embodiments, the air conveying pipeline comprises a first air branch and a second air branch; the first air branch communicates with the ammonia-hydrogen inlet channel premixing pipe, and the second air branch communicates with the third ammonia conveying pipe by means of an air compression pump. In some embodiments, the tail gas conveying pipeline further comprises a third tail gas branch, which is connected to the first air branch by means of a seventh stop valve. In a second aspect, a thermal management method for the vehicle-mounted ammonia cracking hydrogen production system of the ammonia engine is provided, comprising the steps of: obtaining a heating demand type of the vehicle-mounted ammonia cracking hydrogen production system to derive a corresponding control strategy; and in response to the control strategy, controlling supply amounts of ammonia gas and oxygen gas. In some embodiments, when a heating demand is for an engine cold start condition, the control strategy is as follows: the supply amount of the third ammonia conveying pipe and the oxygen supply amount of the air conveying pipe are controlled according to a first gas distribution strategy, so that the heat generated by the ammonia oxidizer heat production pipeline meets the heat required for ammonia cracking in the hydrogen generation pipeline, the heat required to ignite the SCR catalyst during the engine cold start, and the heat required to preheat the ammonia in the first ammonia conveying pipe; the cracking gas storage pipeline is adopted to transport the hydrogen gas generated by the hydrogen generation pipeline to the ammonia-hydrogen inlet channel premixing pipe, in order to ignite the ammonia gas delivered through the second ammonia conveying pipe, thereby completing the engine ignition; and at the same time, tail gas heat from the second tail gas branch preheats the ammonia gas in the third ammonia conveying pipe. In some embodiments, when the heating demand is for an engine steady-state condition, the control strategy is as follows: the supply amount of the third ammonia conveying pipe and the oxygen supply amount of the air conveying pipe are controlled according to a second gas distribution strategy, so that the heat generated by the ammonia oxidizer heat production pipeline and the tail gas heat from the first tail gas branch jointly supply heat to the tail gas after-treatment system; and at the same time, the tail gas heat from the second tail gas branch preheats the ammonia gas in the third ammonia conveying pipe. In some embodiments, when the heating demand is for the engine high-load condition, the control strategy is as follows: the supply amount of the third ammonia conveying pipe and the oxygen supply amount of the air conveying pipe are controlled according to a third gas distribution strategy, so that the heat generated by the ammonia oxidizer heat production pipeline meets the heat required for ammonia cracking in the hydrogen generation pipeline, the heat required for preheating the ammonia gas in the first ammonia conveying pipe, and the heat required by the second hydrogen oxidation hot gas pipeline; the cracking gas storage pipeline is adopted to transport the hydrogen gas generated by the hydrogen generation pipeline to the ammonia-hydrogen inlet channel premixing pipe, in order to ignite the ammonia gas delivered through the second ammonia conveying pipe; at the same time, the tail gas heat from the second tail gas branch preheats the ammonia gas in the third ammonia conveying pipe; and the tail gas heat from the first tail gas branch and the heat from the second hydrogen oxidation hot gas pipeline jointly supply heat to the tail gas after-treatment system. The beneficial effects brought about by the technical solution provided by the present application comprise: The embodiment of the present application provides a vehicle-mounted ammonia cracking hydrogen production system of an ammonia engine, and a thermal management method therefor, a gas outlet end of an ammonia gasification preheating tank is connected to a first ammonia conveying pipe, a second ammonia conveying pipe, a third ammonia conveying pipe and a fourth ammonia conveying pipe; a gas inlet end of a hydrogen generation pipeline is connected to the first ammonia conveying pipe, and a gas outlet end of which is connected to an ammonia-hydrogen inlet channel premixing pipe through a cracking gas storage pipeline; the ammonia-hydrogen inlet channel premixing pipe is further connected to the second ammonia conveying pipe; an ammonia oxidizer heat production pipeline is connected to the third ammonia conveying pipeline and is configured to supply heat to the hydrogen generation pipeline; the ammonia oxidizer heat production pipeline is connected to a first hydrogen oxidation hot gas pipeline and a second hydrogen oxidation hot gas pipeline; the first hydrogen oxidation hot gas pipeline is configured to preheat ammonia gas in the first ammonia conveying pipe; an air conveying pipeline is configured to supply oxygen gas to the ammonia-hydrogen inlet channel premixing pipe and the ammonia oxidizer heat production pipeline, and to control the oxygen conveying amount; a tail gas conveying pipeline comprises a first tail gas branch and a second tail gas branch; the second tail gas branch is configured to preheat the ammonia gas in the third ammonia conveying pipeline; and the first tail gas branch is connected to an gas inlet of a tail gas after-treatment system, and the gas inlet of the tail gas after-treatment system is further connected to the second hydrogen oxidation hot gas pipeline and the fourth ammonia conveying pipe. Through the above pipeline design, the heat of the ammonia oxidizer heat production pipeline not only provides heat for ammonia cracking, but also preheats the ammonia gas required for ammonia cracking, preheats the ammonia gas required for the ammonia oxidizer, and cooperates with the tail gas heat of the engine to jointly supply heat to the after-treatment system. The above heat management methods are selected and operated according to different engine operating conditions; and at the same time, during operation, the molar ratio of the supply amount of ammonia gas to that of air is adjusted through the third ammonia pipe and air conveying pipeline according to the different engine operating conditions, so as to determine the heat release, and ensure that the reaction is in the most appropriate reaction equation, thereby avoiding the generation of tail gas pollutants N2O. Brief Description of the Drawings In order to better illustrate the technical solution in the embodiments of the present application, the following will briefly introduce the drawings needed in the description of the embodiments, and it is obvious that the drawings in the following description are part of embodiments of the present application, for those of ordinary skill in the art, other drawings may also be obtained based on these drawings without any inventive effort. Fig. 1 is a schematic diagram of a vehicle-mounted ammonia cracking hydrogen production system of an ammonia engine in the embodiment of the present application. In the figures: 1-liquid ammonia storage tank; 2-liquid ammonia gasification preheating tank; 3-the first ammonia conveying pipe; 4-cracking gas storage pipeline; 5-the second ammonia conveying pipe; 6-the third ammonia conveying pipe; 7-the fourth ammonia conveying pipe; 8-hydrogen generation pipeline; 9-ammonia oxidizer heat production pipeline; 10-the first hydrogen oxidation hot gas pipeline; 11-the second hydrogen oxidation hot gas pipeline; 12-ammonia-hydrogen inlet channel premixing pipe; 13-the first tail gas branch; 14-the second tail gas branch; 15-the first air branch; 16-the second air branch; 17-the first stop valve; 18-the second stop valve; 19-the third stop valve; 20-the sixth stop valve; 21-the seventh stop valve; 22-the fourth stop valve; 23-ammonia cracker; 24-ammonia oxidizer; 25-the fifth stop valve. Detailed Description of the Embodiments In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without inventive efforts shall fall within the protection scope of the present application. The embodiment of the present application provides a vehicle-mounted ammonia cracking hydrogen production system of an ammonia engine, and a thermal management method therefor, so as to solve the problem in the related art that the heat production of the ammonia oxidation reactor is difficult to control, and the reaction produces NOx and N2O, which worsens the overall vehicle exhaust emissions. As shown in Fig. 1, a vehicle-mounted ammonia cracking hydrogen production system of an ammonia engine comprises a liquid ammonia storage tank 1, a liquid ammonia gasification preheating tank 2, a hydrogen generation pipeline 8, a cracking gas storage pipeline 4, an ammonia-hydrogen inlet channel premixing pipe 12, an ammonia oxidizer heat production pipeline 9, an air conveying pipeline and a tail gas conveying pipeline. The gas outlet end of the liquid ammonia gasification preheating tank 2 is connected to a first ammonia conveying pipe 3, a second ammonia conveying pipe 5, a third ammonia conveying pipe 6 and a fourth ammonia conveying pipe 7. The gas inlet end of the hydrogen generation pipeline 8 is connected to the first ammonia conveying pipe 3, and the gas outlet end thereof is connected to the ammonia-hydrogen inlet channel premixing pipe 12 through the cracking gas storage pipeline 4; the ammonia-hydrogen inlet channel premixing pipe 12 is further connected to the second ammonia conveying pipe 5; the second ammonia conveying pipe 5 is connected to the ammonia-hydrogen inlet channel premixing pipe 12 through an ammonia gas flow sensor and an eighth stop valve; and the ammonia-hydrogen inlet channel premixing pipe 12 is further connected to an intake manifold of the engine. The gas inlet end of the ammonia oxidizer heat production pipeline 9 is connected to the third ammonia conveying pipeline 6 and is configured to supply heat to the hydrogen generation pipeline 8; the gas outlet end of the ammonia oxidizer heat production pipeline 9 is connected to a first hydrogen oxidation hot gas pipeline 10 and a second hydrogen oxidation hot gas pipeline 11; and the first hydrogen oxidation hot gas pipeline 10 is configured to preheat ammonia gas in the first ammonia conveying pipe 3; the air conveying pipeline is configured to supply oxygen gas to the gas inlet ends of the ammonia-hydrogen inlet channel premixing pipe 12 and the ammonia oxidizer heat production pipeline 9, and to control the oxygen conveying amount; the tail gas conveying pipeline is the exhaust pipeline of the engine; the tail gas conveying pipeline comprises a first tail gas branch 13 and a second tail gas branch 14; the second tail gas branch 14 is configured to preheat the ammonia gas in the third ammonia conveying pipeline 6 to 550° C, for cracking in the hydrogen generation pipeline 8; and the first tail gas branch 13 is configured to be connected to an air inlet of a tail gas after-treatment system, and the second hydrogen oxidation hot gas pipeline 11 and the fourth ammonia conveying pipe 7 are also configured to be connected to the air inlet of the tail gas after-treatment system. The ammonia reducing agent of the tail gas after-treatment system is provided by gasifying the liquid ammonia outputted from the fourth ammonia conveying pipe 7, and can replace the function of the urea system of the original after-treatment system. Through the above pipeline arrangement, the heat of the ammonia oxidizer heat production pipeline 9 not only provides heat for ammonia cracking, but also preheats the ammonia gas required by ammonia cracking to react quickly; the ammonia gas required by the ammonia oxidizer heat production pipeline 9 is preheated, and heat is jointly supplied to the after-treatment system in cooperation with tail gas heat of the engine to replace the DOC unit function of the original after-treatment system; the above heat management methods are selected and operated according to different engine operating conditions; at the same time, during operation, the molar ratio of the supply amount of ammonia gas to that of air is adjusted through the third ammonia pipe and air conveying pipeline according to the different engine operating conditions, so as to determine the heat release of the ammonia oxidizer heat production pipeline 9 and ensure that the reaction is performed in the most appropriate reaction equation, thereby avoiding the generation of tail gas pollutants i¥2O. It should be understood that the above adjustment of the molar ratio of the supply amount of ammonia gas to that of oxygen gas in air is made to change the chemical reaction equation under different operating reactions so as to avoid the generation of tail gas pollutants Af2O. The reaction equations are as follows: Reaction Equation 1: (1W + 0.750, 0.5 M + = -2.26 X 10s Reaction Equation 2: (2)W3 + O2 ^0.5^0 + 1.5¾¾ Iff = -2.76X Reaction Equation 3: (3)W2 + 1.2 SO2 >0 + 1.5¾ 0; J / f = -317 X Reaction Equation 4: (4)^¾ + 1.75O2 4- 1.5¾¾ Iff = -2.83 x: lQ5j / moteJW3 That is, through controlling the molar ratio of the supply amount of ammonia gas to that of oxygen gas in air, the ammonia reaction equation of the ammonia oxidizer heat production pipeline 9 is prevented from operating in reaction equation 2, thereby avoiding the generation of tail gas pollutants JV2O. In some preferred embodiments, the structure of the liquid ammonia gasification preheating tank 2 is configured as follows: the liquid ammonia gasification preheating tank 2 comprises a primary preheating chamber and a secondary preheating chamber which are communicated with each other; the primary preheating chamber communicates with the second tail gas branch 14, and is connected to the third ammonia conveying pipe 6 and the second ammonia conveying pipe 5, so as to perform primary preheating on the ammonia gas therein to a temperature of 150°C for the ammonia oxidation ignition point, and to be used by the ammonia oxidizer heat production pipeline 9; the secondary preheating chamber is connected to the first ammonia conveying pipe 3 and the fourth ammonia conveying pipe 7, and the first hydrogen oxidation hot gas pipeline 10 communicates with the secondary preheating chamber, so as to perform preheating on the ammonia gas in the third ammonia delivery pipe 6 to a temperature of 550°C. In some preferred embodiments, the structures of the hydrogen generation pipeline 8 and the ammonia oxidizer heat production pipeline 9 are described in detail: the hydrogen generation pipeline 8 comprises a first stop valve 17, an ammonia cracker 23, a cracking gas collection pipe, and a second stop valve 18 which are connected successively; the ammonia oxidizer heat production pipeline 9 comprises a third stop valve 19, an ammonia oxidizer 24 and a gas outlet pipe which are connected successively; and heat is exchanged between the ammonia oxidizer 24 and the ammonia cracker 23 by means of a heat exchanger. The efficiency calibration of heat exchange is performed between ammonia gas in the inner flow channel of the ammonia cracker 23 and ammonia oxidation hot flue gas in the outer flow channel of the ammonia oxidizer 24. The ammonia supply amount to the ammonia cracker 23 and the hydrogen production amount from the cracking process are matched, that is, after the selection of catalyst and heat exchanger for the ammonia cracker 23 is determined, the corresponding relationship between the two is calibrated through experimentation. Further, the cracking gas storage pipeline 4 comprises a mixed gas buffer tank, a hydrogen flow meter and a sixth stop valve 20 which are connected successively; the air conveying pipeline comprises a first air branch 15 and a second air branch 16; the first air branch 15 communicates with the ammonia-hydrogen inlet channel premixing pipe 12, and the second air branch 16 communicates with the third ammonia conveying pipe 6 by means of an air compression pump; and the tail gas conveying pipeline further comprises a third tail gas branch, which is connected to the first air branch 15 by means of a seventh stop valve 21. The second hydrogen oxidation hot gas pipeline 11 comprises a first pipeline and a fourth stop valve 22; and the second tail gas branch 14 comprises a second pipeline and a fifth stop valve 25. The above-described molar ratio of the supply amount of ammonia gas to that of oxygen gas in air is controlled through an air compression pump to control the supply amount of air, and the supply amount of ammonia gas is controlled through an ammonia injector of the corresponding ammonia conveying pipe; and the first ammonia conveying pipe 3, the second ammonia conveying pipe 5, the third ammonia conveying pipe 6 and the fourth ammonia conveying pipe 7 are each provided with a corresponding ammonia injector. The present application further provides a thermal management method for a vehicle-mounted ammonia cracking hydrogen production system of an ammonia engine, which comprises the following steps: SOI: A heating demand type of the vehicle-mounted ammonia cracking hydrogen production system is obtained to derive a corresponding control strategy; and S02: In response to the control strategy, supply amounts of ammonia gas and oxygen gas are controlled, and the specific description is as follows: S020: When a heating demand is for an engine cold start condition, the control strategy is as follows: the supply amount of the third ammonia conveying pipe 6 and the oxygen supply amount of the air conveying pipe are controlled according to a first gas distribution strategy, so that the heat generated by the ammonia oxidizer heat production pipeline 9 meets the heat required for ammonia cracking in the hydrogen generation pipeline 8, the heat required to ignite the SCR catalyst during the engine cold start, and the heat required to preheat the ammonia gas in the first ammonia conveying pipe 3. The gas distribution strategy 1 is the reaction equation 1. The cracking gas storage pipeline 4 is adopted to transport the hydrogen gas generated by the hydrogen generation pipeline 8 to the ammonia-hydrogen inlet channel premixing pipe 12, in order to ignite the ammonia gas delivered through the second ammonia conveying pipe 5, thereby completing the engine ignition; and at the same time, tail gas heat from the second tail gas branch 14 preheats the ammonia gas in the third ammonia conveying pipe 6. S021: When the heating demand is for an engine steady-state condition, the control strategy is as follows: the supply amount of the third ammonia conveying pipe 6 and the oxygen supply amount of the air conveying pipe are controlled according to a second gas distribution strategy, so that the heat generated by the ammonia oxidizer heat production pipeline 9 and the tail gas heat from the first tail gas branch 13 jointly supply heat to the tail gas after-treatment system; and at the same time, the tail gas heat from the second tail gas branch 14 preheats the ammonia gas in the third ammonia conveying pipe 6. The gas distribution strategy 2 is the reaction equation 4. S022: The heating demand is for the engine high-load condition, the control strategy is as follows: the supply amount of the third ammonia conveying pipe 6 and the oxygen supply amount of the air conveying pipe are controlled according to a third gas distribution strategy, so that the heat generated by the ammonia oxidizer heat production pipeline 9 meets the heat required for ammonia cracking in the hydrogen generation pipeline 8, the heat required for preheating the ammonia gas in the first ammonia conveying pipe 3, and the heat required by the second hydrogen oxidation hot gas pipeline 11. The gas distribution strategy 3 is the reaction equation 3. The cracking gas storage pipeline 4 is adopted to transport the hydrogen gas generated by the hydrogen generation pipeline 8 to the ammonia-hydrogen inlet channel premixing pipe 12, in order to ignite the ammonia gas delivered through the second ammonia conveying pipe 5; at the same time, the tail gas heat from the second tail gas branch 14 preheats the ammonia gas in the third ammonia conveying pipe 6; and the tail gas heat from the first tail gas branch 13 and the heat from the second hydrogen oxidation hot gas pipeline 11 jointly supply heat to the tail gas after-treatment system, so as to replace the DOC unit function of the original after-treatment system. Through the above structural setting and thermal management method, the vehicle-mounted ammonia cracking hydrogen production system of the ammonia engine has the following heat distribution parts: Part 1: The liquid ammonia gasification preheating tank 2 absorbs heat, and the absorbed heat comes from the second tail gas branch 14 and the first hydrogen oxidation hot gas pipeline 10. Part 2: Gas distribution and heat release of the ammonia oxidizer heat production pipeline 9; the first ammonia delivery pipe 3 and the second air branch 16 are adopted to provide ammonia gas and oxygen gas, which react with each other to release heat; and the released heat participates in the ammonia cracking of the hydrogen generation pipeline 8, and is transmitted to the tail gas after-treatment system and the liquid ammonia gasification preheating tank 2. Part 3: The hydrogen generation pipeline 8 absorbs heat to crack ammonia gas to form hydrogen gas, and the hydrogen gas and ammonia gas participate in the ignition and high-load movement of the engine. Part 4: The tail gas after-treatment system absorbs the heat from the first tail gas branch 13 and the second hydrogen oxidation hot gas pipeline 11. In summary, the thermal management problem centered on the ammonia oxidizer can be solved, and at the same time, the ammonia reaction equation of the ammonia oxidizer heat production pipeline 9 can be prevented from operating in reaction equation 2, thereby avoiding the generation of tail gas pollutants 1VZO. In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", etc. are based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, instead of indicating or implying that the pointed device or element must have a specific orientation, be configured and operated in a specific orientation, therefore it may not be understood as a limitation of the present invention. Unless otherwise clearly specified and limited, the terms "installation", "connected" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; further can be a mechanical connection, or an electrical connection; further can be directly connected, or indirectly connected through an intermediate medium, or can be the internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above-mentioned terms in the present application may be understood according to specific circumstances. It should be noted that relational terms such as "first" and "second" are only for distinguishing one entity or operation from another entity or operation in the present application, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only comprises those elements, but also comprises those that are not explicitly listed, or further comprises elements inherent to the process, method, article, or device. If there are no more restrictions, the elements defined by the sentence "comprising a.." does not exclude the existence of other same elements in the process, method, article, or device comprising the elements. Those skilled in the art should understand that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application can adopt the fonn of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may be in the form of a computer program product implemented in one or more computer-usable storage media (comprising but not limited to disk memory, CD-ROM, and optical memory, etc.) with computer available program codes. The present application is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products in embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing equipment so as to generate a machine, so that the instructions executed by the computer or other programmable data processing equipment are caused to generate a device for implementing the functions specified in one or more processes in the flowchart and / or one or more blocks in the block diagram. These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing devices to work in a particular manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising a command device. The command device implements the functions specified in one or more flows in the flow diagram and / or one or more blocks in the block diagram. These computer program instructions may also be loaded onto a computer or other programmable data processing device, so that a series of steps are executed on the computer or other programmable equipment to produce computer-implemented processing, thus, the instructions executed on the computer or other programmable devices provide steps for implementing the functions specified in one or more flows in the flow diagram and / or one or more blocks in the block diagram. In a typical configuration, a computing device comprises one or more processors (CPU), input / output interfaces, network interfaces, and memory. The memory may comprise non-permanent memory in a computer-readable medium, random-access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium. The computer-readable media comprise both permanent and non-permanent, removable and non-removable media that may be implemented by any method or technology for storage of information. The information may be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media comprise, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk-read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. According to the definition in this article, the computer-readable media does not comprise transitory media, such as modulated data signals and carrier waves. It should also be noted that the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, product or device comprising a series of elements not only comprises those elements, but also comprises those that are not explicitly listed, or further comprises elements inherent to the process, method, product, or device. If there are no more restrictions, the elements defined by the sentence "comprising a..." does not exclude the existence of other same elements in the process, method, product, or device comprising the elements. The above-mentioned are only the embodiments of the present application, so that those skilled in the art can understand or implement the present application. For those skilled in the art, various modifications to these embodiments will be obvious, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown in this document, but will be subject to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A vehicle-mounted ammonia cracking hydrogen production system of an ammonia engine, comprising:a liquid ammonia storage tank (1) and a liquid ammonia gasification preheating tank (2) connected successively; a gas outlet end of the liquid ammonia gasification preheating tank (2) is connected to a first ammonia conveying pipe (3), a second ammonia conveying pipe (5), a third ammonia conveying pipe (6) and a fourth ammonia conveying pipe (7);a hydrogen generation pipeline (8), a gas inlet end of which is connected to the first ammonia conveying pipe (3), and a gas outlet end of which is connected to an ammonia-hydrogen inlet channel premixing pipe (12) through a cracking gas storage pipeline (4); the ammonia-hydrogen inlet channel premixing pipe (12) is further connected to the second ammonia conveying pipe (5);an ammonia oxidizer heat production pipeline (9), which is connected to the third ammonia conveying pipeline (6) and is configured to supply heat to the hydrogen generation pipeline (8); the ammonia oxidizer heat production pipeline (9) is connected to a first hydrogen oxidation hot gas pipeline (10) and a second hydrogen oxidation hot gas pipeline (11); and the first hydrogen oxidation hot gas pipeline (10) is configured to preheat ammonia gas in the first ammonia conveying pipe (3);an air conveying pipeline, which is configured to supply oxygen gas to the ammonia-hydrogen inlet channel premixing pipe (12) and the ammonia oxidizer heat production pipeline (9), and to control the oxygen conveying amount;a tail gas conveying pipeline, which comprises a first tail gas branch (13) and a second tail gas branch (14); the second tail gas branch (14) is configured to preheat the ammonia gas in the third ammonia conveying pipeline (6); and the first tail gas branch (13) is configured to be connected to an gas inlet of a tail gas after-treatment system, and the second hydrogen oxidation hot gas pipeline (11) and the fourth ammonia conveying pipe (7) are also configured to be connected to the gas inlet of the tail gas after-treatment system.

2. The vehicle-mounted ammonia cracking hydrogen production system of the ammonia engine according to claim 1, whereinthe liquid ammonia gasification preheating tank (2) comprises a primary preheating chamber and a secondary preheating chamber whichare communicated with each other;the primary preheating chamber communicates with the second tail gas branch (14), and is connected to the third ammonia conveying pipe (6) and the second ammonia conveying pipe (5); andthe secondary preheating chamber is connected to the first ammonia conveying pipe (3) and the fourth ammonia conveying pipe (7), and the first hydrogen oxidation hot gas pipeline (10) communicates with the secondary preheating chamber.

3. The vehicle-mounted ammonia cracking hydrogen production system of the ammonia engine according to claim 1, whereinthe hydrogen generation pipeline (8) comprises a first stop valve (17), an ammonia cracker (23), a cracking gas collection pipe, and a second stop valve (18) which are connected successively;the ammonia oxidizer heat production pipeline (9) comprises a third stop valve (19), an ammonia oxidizer (24) and a gas outlet pipe which are connected successively; and heat is exchanged between the ammonia oxidizer (24) and the ammonia cracker (23) by means of a heat exchanger.

4. The vehicle-mounted ammonia cracking hydrogen production system of the ammonia engine according to claim 1, whereinthe cracking gas storage pipeline (4) comprises a mixed gas buffer tank, a hydrogen flow meter and a sixth stop valve (20) which are connected successively.

5. The vehicle-mounted ammonia cracking hydrogen production system of the ammonia engine according to claim 1, whereinthe air conveying pipeline comprises a first air branch (15) and a second air branch (16); the first air branch (15) communicates with the ammonia-hydrogen inlet channel premixing pipe (12), and the second air branch (16) communicates with the third ammonia conveying pipe (6) by means of an air compression pump.

6. The vehicle-mounted ammonia cracking hydrogen production system of the ammonia engine according to claim 5, whereinthe tail gas conveying pipeline further comprises a third tail gas branch, which is connected to the first air branch (15) by means of a seventh stop valve (21).

7. A thermal management method for the vehicle-mounted ammonia cracking hydrogen production system of the ammonia engine accordingto claim 1, comprising the steps of:obtaining a heating demand type of the vehicle-mounted ammonia cracking hydrogen production system to derive a corresponding control strategy; andin response to the control strategy, controlling supply amounts of ammonia gas and oxygen gas.

8. The thermal management method for the vehicle-mounted ammonia cracking hydrogen production system of the ammonia engine according to claim 7, whereinwhen a heating demand is for an engine cold start condition, the control strategy is as follows:the supply amount of the third ammonia conveying pipe (6) and the oxygen supply amount of the air conveying pipe are controlled according to a first gas distribution strategy, so that the heat generated by the ammonia oxidizer heat production pipeline (9) meets the heat required for ammonia cracking in the hydrogen generation pipeline (8), the heat required to ignite the SCR catalyst during the engine cold start, and the heat required to preheat the ammonia in the first ammonia conveying pipe (3);the cracking gas storage pipeline (4) is adopted to transport the hydrogen gas generated by the hydrogen generation pipeline (8) to the ammonia-hydrogen inlet channel premixing pipe (12), in order to ignite the ammonia gas delivered through the second ammonia conveying pipe (5), thereby completing the engine ignition; and at the same time, tail gas heat from the second tail gas branch (14) preheats the ammonia gas in the third ammonia conveying pipe (6).

9. The thermal management method for the vehicle-mounted ammonia cracking hydrogen production system of the ammonia engine according to claim 7, whereinwhen the heating demand is for an engine steady-state condition, the control strategy is as follows:the supply amount of the third ammonia conveying pipe (6) and the oxygen supply amount of the air conveying pipe are controlled according to a second gas distribution strategy, so that the heat generated by the ammonia oxidizer heat production pipeline (9) and the tail gas heat from the first tail gas branch (13) jointly supply heat to the tail gas after-treatment system; and at the same time, the tail gas heat from the second tail gas branch (14) preheats the ammonia gas in the thirdammonia conveying pipe (6).

10. The thermal management method for the vehicle-mounted ammonia cracking hydrogen production system of the ammonia engine according to claim 7, whereinwhen the heating demand is for the engine high-load condition, the control strategy is as follows:the supply amount of the third ammonia conveying pipe (6) and the oxygen supply amount of the air conveying pipe are controlled according to a third gas distribution strategy, so that the heat generated by the ammonia oxidizer heat production pipeline (9) meets the heat required for ammonia cracking in the hydrogen generation pipeline (8), the heat required for preheating the ammonia gas in the first ammonia conveying pipe (3), and the heat required by the second hydrogen oxidation hot gas pipeline (11);the cracking gas storage pipeline (4) is adopted to transport the hydrogen gas generated by the hydrogen generation pipeline (8) to the ammonia-hydrogen inlet channel premixing pipe (12), in order to ignite the ammonia gas delivered through the second ammonia conveying pipe (5); at the same time, the tail gas heat from the second tail gas branch (14) preheats the ammonia gas in the third ammonia conveying pipe (6); and the tail gas heat from the first tail gas branch (13) and the heat from the second hydrogen oxidation hot gas pipeline (11) jointly supply heat to the tail gas after-treatment system.

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