Low-energy-consumption ammonia cracking hydrogen production device and control method

Abstract

The application discloses a low-energy-consumption ammonia cracking hydrogen production device and a control method. The device comprises an ammonia preheating assembly, an ammonia cracking combustion assembly, an ammonia supply assembly and an air supply assembly. The ammonia preheating assembly is provided with an ammonia heat exchange channel, a cracking gas heat exchange channel and a waste gas heat exchange channel, and the three channels perform cascade heat exchange through an interwall. The ammonia cracking combustion assembly is provided with an ammonia cracking channel and an ammonia combustion chamber, the ammonia combustion chamber surrounds the outer periphery of the ammonia cracking channel and directly transfers heat through an interwall; an ammonia gas outlet is connected with a fuel inlet and an ammonia gas inlet respectively, a cracking gas discharge outlet is connected with a cracking gas inlet, and a waste gas discharge outlet is connected with a waste gas inlet. The ammonia supply assembly supplies ammonia gas, and the air supply assembly supplies combustion air. The application surrounds the ammonia combustion chamber to directly supply heat, avoids external heat source loss, simultaneously utilizes two-stage cascade heat exchange of cracking gas and combustion waste gas, significantly improves heat efficiency, reduces external energy consumption, and realizes long-time continuous and stable hydrogen production.

Description

Technical Field

[0001] This invention relates to the field of ammonia-to-hydrogen technology, and in particular to a low-energy-consumption ammonia cracking hydrogen production device and control method. Background Technology

[0002] In the ammonia thermocatalytic cracking process for hydrogen production, a continuous supply of heat energy is required to maintain catalyst activity and ensure efficient ammonia conversion. Traditionally, this heat energy is mainly supplied directly from an external independent heat source. However, this heating method is energy-intensive and contradicts the development goal of low-carbon hydrogen production. To improve overall energy efficiency, existing research attempts to use waste heat recovery technology to capture waste heat generated within the system and use it for heating the ammonia cracking reaction. However, current waste heat recovery technologies generally suffer from low thermal efficiency in practical applications. For example, due to low heat source grade, poor heat exchange coupling, or excessively long heat transfer paths, the recovered heat energy is often severely lost, making it difficult to efficiently and stably transport the waste heat to the reaction zone. Furthermore, the waste heat supply often fluctuates with the upstream process conditions, easily leading to discontinuous reactor heating and difficulty in temperature control, further restricting the improvement of ammonia cracking hydrogen production performance. In summary, existing waste heat recovery methods still cannot meet the actual requirements of low energy consumption and high efficiency in the ammonia cracking hydrogen production process, and there is an urgent need to develop more efficient waste heat utilization methods. Summary of the Invention

[0003] The purpose of this invention is to provide a low-energy-consumption ammonia cracking hydrogen production device and control method to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions.

[0004] The technical solution adopted to solve the above-mentioned technical problems is as follows: This invention provides a low-energy-consumption ammonia cracking hydrogen production device, comprising: The ammonia preheating assembly includes an ammonia heat exchange channel, a cracked gas heat exchange channel, and a waste gas heat exchange channel. The ammonia heat exchange channel has an ammonia inlet and an ammonia outlet, the cracked gas heat exchange channel has a cracked gas inlet and a cracked gas outlet, and the waste gas heat exchange channel has a waste gas inlet and a waste gas outlet. The ammonia heat exchange channel exchanges heat with the cracked gas heat exchange channel and the waste gas heat exchange channel through partition walls. An ammonia cracking combustion assembly includes an ammonia cracking channel and an ammonia combustion chamber. The ammonia cracking channel contains an ammonia cracking catalyst and has an ammonia inlet and a cracked gas outlet. The ammonia combustion chamber contains an ammonia combustion catalyst and has a fuel inlet and an exhaust gas outlet. The ammonia combustion chamber surrounds the ammonia cracking channel and exchanges heat with it through a partition wall. The ammonia outlet is connected to both the fuel inlet and the ammonia inlet. The cracked gas outlet is connected to the cracked gas inlet. The exhaust gas outlet is connected to the exhaust gas inlet. An ammonia supply assembly, connected to the ammonia inlet, is used to supply ammonia to the ammonia heat exchange channel; An air supply assembly, connected to the fuel inlet, is used to supply the air required for combustion to the ammonia combustion chamber.

[0005] The advantages of the low-energy ammonia cracking hydrogen production device of the present invention are: The ammonia combustion chamber surrounds the ammonia cracking channel and directly exchanges heat through the partition wall, enabling efficient and uniform transfer of combustion heat to the cracking reaction zone. This avoids the heat loss problems of traditional external heating methods. Furthermore, by setting up ammonia heat exchange channels, cracked gas heat exchange channels, and exhaust gas heat exchange channels, a two-stage heat exchange is achieved between the high-temperature gas generated from cracking and the high-temperature exhaust gas generated from combustion. The cracked gas first preheats the feedstock ammonia through the cracked gas heat exchange channel, and the combustion exhaust gas undergoes secondary preheating and insulation through the exhaust gas heat exchange channel. This significantly improves the system's thermal efficiency, reduces external energy consumption, and achieves lower energy consumption and continuous hydrogen supply over long periods.

[0006] As a further improvement to the above technical solution, the ammonia preheating assembly includes a first heat exchange shell and a second heat exchange shell; The first heat exchange shell is provided with a first confluence cavity, a first heat exchange cavity, a second heat exchange cavity, and a second confluence cavity arranged sequentially along the axial direction; the first heat exchange cavity is provided with a plurality of first heat exchange tubes, one end of each first heat exchange tube is connected to the second heat exchange cavity, and the other end is connected to the first confluence cavity; the second heat exchange cavity is provided with a plurality of second heat exchange tubes, one end of each second heat exchange tube is connected to the first heat exchange cavity, and the other end is connected to the second confluence cavity; The first heat exchange chamber, a plurality of second heat exchange tubes, and the second confluence chamber are sequentially connected to form the ammonia heat exchange channel. The ammonia inlet is located in the first heat exchange chamber, and the ammonia outlet is located in the second confluence chamber. The second heat exchange chamber, a plurality of first heat exchange tubes, and the first confluence chamber are sequentially connected to form the cracked gas heat exchange channel. The cracked gas inlet is located in the second heat exchange chamber, and the cracked gas outlet is located in the first confluence chamber. The second heat exchange shell is nested around the outer periphery of the first heat exchange shell and corresponds to the position of the first heat exchange cavity. The exhaust gas heat exchange channel is formed between the first heat exchange shell and the second heat exchange shell.

[0007] As a further improvement to the above technical solution, the first heat exchange tube is in the shape of a spiral tube, and the second heat exchange tube is in the shape of a straight tube.

[0008] As a further improvement to the above technical solution, the pyrolysis gas outlet is connected to a gas separator, which is used to purify the pyrolysis gas to obtain hydrogen; the waste gas outlet is connected to a waste gas processor, which is used to purify the waste gas.

[0009] As a further improvement to the above technical solution, a booster pump is provided between the cracked gas outlet and the cracked gas inlet. The booster pump is used to pressurize the cracked gas discharged from the ammonia cracking channel and then deliver it to the cracked gas heat exchange channel.

[0010] As a further improvement to the above technical solution, a distribution regulating valve is provided between the ammonia outlet and the fuel inlet and the ammonia inlet. The distribution regulating valve is used to adjust the ammonia flow rate ratio from the ammonia outlet to the fuel inlet and the ammonia inlet.

[0011] As a further improvement to the above technical solution, the air supply component includes an air compressor, the outlet of which is connected to the fuel inlet, and the air compressor is used to regulate the air flow rate supplied to the ammonia combustion chamber.

[0012] As a further improvement to the above technical solution, a signal acquisition component is also included, the signal acquisition component comprising: Nitrogen oxide concentration detector, used to monitor the NOx concentration in combustion exhaust gas; A temperature sensor array is used to monitor the temperature of the reaction zone within the ammonia cracking channel; An air-fuel ratio sensor is used to monitor the mixing ratio of ammonia and air entering the combustion chamber; An ammonia flow sensor is used to monitor the flow rate of ammonia gas passing through the ammonia inlet. A differential pressure sensor is used to monitor the pressure difference between the ammonia inlet and the cracked gas outlet; A temperature difference sensor is used to monitor the temperature difference between the exhaust gas inlet and the exhaust gas outlet; A catalyst activity monitor is used to monitor the activity of the ammonia cracking catalyst.

[0013] As a further improvement to the above technical solution, it also includes an intelligent control component, which includes a controller module that is connected to the signal acquisition component. The controller module is connected to the booster pump, the distribution regulating valve and the air compressor respectively. The controller module is configured as follows: When the real-time temperature of the reaction zone in the ammonia cracking channel is lower than the preset temperature threshold, the proportion of ammonia gas allocated to the ammonia combustion chamber is increased to enhance catalytic combustion and achieve rapid thermal compensation. When the NOx concentration in the combustion exhaust gas is higher than a preset concentration threshold, the power of the air compressor is adjusted to change the air-fuel ratio and reduce the NOx concentration. When the activity characterization parameters of the ammonia cracking catalyst are lower than a preset threshold, the controller module adjusts the proportion of ammonia gas allocated to the ammonia combustion chamber according to the real-time temperature and ammonia conversion rate of the reaction zone in the ammonia cracking channel, so as to maintain the temperature of the reaction zone within the preset temperature range.

[0014] Furthermore, this invention also proposes a control method for an ammonia cracking hydrogen production device, applicable to the aforementioned low-energy-consumption ammonia cracking hydrogen production device, the control method comprising: According to the preset hydrogen production rate, ammonia gas is continuously input into the ammonia heat exchange channel according to the preset ammonia flow rate. According to the preset mixing ratio, a portion of the preheated ammonia gas is mixed with air and then sent into the ammonia combustion chamber for catalytic combustion, while another portion of the preheated ammonia gas is sent into the ammonia cracking channel for cracking reaction. The heat generated by catalytic combustion is controlled to heat the ammonia cracking channel, and the resulting high-temperature waste gas flows through the waste gas heat exchange channel to preheat and keep the ammonia in the ammonia heat exchange channel warm. The high-temperature pyrolysis gas generated by the pyrolysis reaction is controlled to flow through the pyrolysis gas heat exchange channel to preheat the ammonia gas in the ammonia heat exchange channel; The pyrolysis gas after heat exchange is purified to obtain hydrogen.

[0015] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments; Figure 1 This is a schematic diagram of an embodiment of the low-energy ammonia cracking hydrogen production device provided by the present invention. Figure 2 This is a schematic diagram of an embodiment of the ammonia preheating component provided by the present invention; Figure 3 This is a flowchart of an embodiment of the control method for an ammonia cracking hydrogen production device provided by the present invention; Icon labels: Ammonia preheating assembly 100; ammonia heat exchange channel 110; ammonia inlet 111; ammonia flow sensor 1111; ammonia outlet 112; cracked gas heat exchange channel 120; cracked gas inlet 121; cracked gas outlet 122; waste gas heat exchange channel 130; waste gas inlet 131; waste gas outlet 132; temperature difference sensor 133; first heat exchange shell 140; first merging chamber 141; first heat exchange chamber 142; second heat exchange chamber 143; second merging chamber 144; first heat exchange tube 145; second heat exchange tube 146; second heat exchange shell 150; Ammonia cracking combustion assembly 200; ammonia cracking channel 210; ammonia inlet 211; cracked gas outlet 212; temperature sensor array 213; differential pressure sensor 214; catalyst activity monitor 215; ammonia combustion chamber 220; fuel inlet 221; air-fuel ratio sensor 2211; exhaust gas outlet 222; nitrogen oxide concentration detector 2221; Ammonia supply assembly 300; Ammonia storage tank 310; Air supply unit 400; air compressor 410; Gas separator 500; Exhaust gas processor 600; 700 booster air pump; Distribution regulating valve 800. Detailed Implementation

[0017] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0018] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0019] In the description of this invention, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features or their sequential relationship.

[0020] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are some embodiments of the present invention, not all embodiments.

[0022] Reference Figure 1 and Figure 2 The low-energy-consumption ammonia cracking hydrogen production device of the present invention is illustrated in the following embodiments: like Figure 1 As shown, the low-energy ammonia cracking hydrogen production device of the present invention includes: an ammonia preheating component 100, an ammonia cracking combustion component 200, an ammonia supply component 300, and an air supply component 400.

[0023] The ammonia preheating assembly 100 is used to preheat the ammonia gas to be cracked. The heat source it utilizes comes from the high-temperature cracked gas generated by the ammonia cracking reaction in the ammonia cracking combustion assembly 200 and the high-temperature waste gas generated by the ammonia catalytic combustion. The ammonia preheating assembly 100 is provided with an ammonia heat exchange channel 110, a cracked gas heat exchange channel 120 and a waste gas heat exchange channel 130, wherein the ammonia heat exchange channel 110 exchanges heat with the cracked gas heat exchange channel 120 and the waste gas heat exchange channel 130 through partition walls.

[0024] Specifically, such as Figure 1 and Figure 2 As shown, the ammonia heat exchange channel 110 has an ammonia inlet 111 and an ammonia outlet 112. An ammonia supply assembly 300 is connected to the ammonia inlet 111 and is used to supply ammonia to the ammonia heat exchange channel 110. In this embodiment, the ammonia supply assembly 300 includes an ammonia storage tank 310, and the input amount of ammonia is controlled by the ammonia storage tank 310 and its outlet flow valve. The ammonia outlet 112 is connected to the corresponding inlet of the ammonia cracking combustion assembly 200, as detailed below.

[0025] like Figure 1 and Figure 2 As shown, the cracked gas heat exchange channel 120 has a cracked gas inlet 121 and a cracked gas outlet 122. The cracked gas inlet 121 is used to receive high-temperature cracked gas from the ammonia cracking channel 210, and the cracked gas outlet 122 is connected to the gas separator 500. After heat exchange, the cracked gas enters the gas separator 500 for purification, and finally high-purity hydrogen is obtained.

[0026] like Figure 1 and Figure 2 As shown, the exhaust gas heat exchange channel 130 has an exhaust gas inlet 131 and an exhaust gas outlet 132. The exhaust gas inlet 131 is used to receive high-temperature exhaust gas from the ammonia combustion chamber 220, and the exhaust gas outlet 132 is connected to the exhaust gas processor 600, which is used to purify the exhaust gas to ensure that the emissions meet the standards.

[0027] like Figure 1As shown, the ammonia cracking combustion assembly 200 of this embodiment of the invention is provided with an ammonia cracking channel 210 and an ammonia combustion chamber 220.

[0028] The ammonia cracking channel 210 contains an ammonia cracking catalyst and has an ammonia inlet 211 and a cracked gas outlet 212. The ammonia inlet 211 is connected to the aforementioned ammonia outlet 112, and the cracked gas outlet 212 is connected to the cracked gas inlet 121. In this embodiment, the ammonia cracking catalyst can be a conventional supported metal catalyst for ammonia cracking, such as a ruthenium-based, nickel-based, or iron-based catalyst. As a specific embodiment, the ammonia cracking catalyst is a Ru / Al2O3 catalyst, wherein the Ru loading is 8.5 wt.%. The catalyst can be a commercially available product or prepared by conventional impregnation and calcination methods. The ammonia cracking channel 210 has a microporous structure, and the catalyst can be attached to the inner wall of the microchannel of the cordierite support through a coating layer. The porous structure is beneficial to increasing the contact area between ammonia and the catalyst, thereby improving the efficiency of the ammonia cracking reaction.

[0029] like Figure 1 As shown, the ammonia combustion chamber 220 contains an ammonia combustion catalyst and has a fuel inlet 221 and an exhaust outlet 222. The fuel inlet 221 is connected to the ammonia outlet 112 and also to the air supply assembly 400. The exhaust outlet 222 is connected to the exhaust inlet 131. The air supply assembly 400 supplies the air required for combustion to the ammonia combustion chamber 220. In this embodiment, the air supply assembly 400 includes an air compressor 410, and the air supply is controlled by adjusting the power of the air compressor 410.

[0030] During operation, preheated ammonia gas is mixed with air in a preset ratio to form fuel, which is then introduced into the ammonia combustion chamber 220. With the preheating effect of the ammonia preheating component 100, the temperature of the mixed fuel rises to the ignition temperature of the ammonia combustion catalyst, thus initiating a catalytic combustion reaction. The ammonia combustion chamber 220 has a kiln-like cylindrical structure, completely surrounding the outer periphery of the ammonia cracking channel 210, and exchanges heat with the ammonia cracking channel 210 through a partition wall. The heat generated by combustion is directly, efficiently, and uniformly transferred to the inner ammonia cracking channel 210, providing stable energy for the ammonia cracking reaction.

[0031] In this invention, the ammonia preheating component 100 is provided with independent but coupled ammonia heat exchange channel 110, cracked gas heat exchange channel 120, and waste gas heat exchange channel 130. The raw ammonia stream flows through the ammonia heat exchange channel 110, where it undergoes counter-current heat exchange with the high-temperature cracked gas flowing through the cracked gas heat exchange channel 120 and the high-temperature waste gas flowing through the waste gas heat exchange channel 130. The cracked gas first transfers its sensible heat to the ammonia, completing the first-stage preheating; subsequently, the waste gas further transfers its remaining heat to the ammonia, completing the second-stage preheating and providing insulation.

[0032] This enables the cascade utilization of thermal energy, maximizes the recovery of waste heat from high-temperature gases generated within the system, significantly reduces external heating demand, and improves the overall thermal efficiency of the system by more than 20%, meeting the requirements for low-energy hydrogen production.

[0033] The combustion chamber and the ammonia cracking channel 210 are separated by only one partition wall. The heat generated by catalytic combustion is directly conducted to the cracking reaction zone through the partition wall. Since the combustion chamber surrounds the ammonia cracking channel 210, the temperature field is uniformly distributed, eliminating the heat loss caused by the transmission of heat through pipelines in the traditional external heating method. The heat transfer path is the shortest, the thermal response speed is fast, and it can quickly compensate for the heat required for the cracking reaction, maintain the temperature stability of the reaction zone, and improve the dynamic performance of the system.

[0034] Regarding the specific structure of the ammonia preheating assembly 100, the ammonia preheating assembly 100 adopts a composite heat exchange structure, specifically including a first heat exchange shell 140 and a second heat exchange shell 150, as follows: Figure 2 As shown.

[0035] The first heat exchange shell 140 is a shell-and-tube heat exchanger structure, and its interior is provided with a first confluence chamber 141, a first heat exchange chamber 142, a second heat exchange chamber 143, and a second confluence chamber 144 arranged sequentially along the axial direction. The first heat exchange chamber 142 and the second heat exchange chamber 143 are used to realize heat exchange between different heat source media and ammonia gas, and the first confluence chamber 141 and the second confluence chamber 144 are used to collect or distribute the media after heat exchange.

[0036] Specifically, the first heat exchange chamber 142 is provided with a plurality of first heat exchange tubes 145. One end of each first heat exchange tube 145 is connected to the second heat exchange chamber 143, and the other end is connected to the first confluence chamber 141. The second heat exchange chamber 143 is provided with a plurality of second heat exchange tubes 146, one end of each second heat exchange tube 146 is connected to the first heat exchange chamber 142, and the other end is connected to the second confluence chamber 144.

[0037] Furthermore, the second heat exchange shell 150 is nested around the outer periphery of the first heat exchange shell 140 and corresponds to the position of the first heat exchange cavity 142.

[0038] Through the above connection, three independent heat exchange channels are formed: Ammonia heat exchange channel 110: Formed by sequentially connecting a first heat exchange chamber 142, multiple second heat exchange tubes 146, and a second confluence chamber 144. An ammonia inlet 111 is located in the first heat exchange chamber 142, and an ammonia outlet 112 is located in the second confluence chamber 144. Raw ammonia gas enters from the first heat exchange chamber 142, flows through the multiple second heat exchange tubes 146, and then converges in the second confluence chamber 144 before being discharged.

[0039] The cracked gas heat exchange channel 120 is formed by sequentially connecting a second heat exchange chamber 143, multiple first heat exchange tubes 145, and a first confluence chamber 141. The cracked gas inlet 121 is located in the second heat exchange chamber 143, and the cracked gas outlet 122 is located in the first confluence chamber 141. High-temperature cracked gas enters from the second heat exchange chamber 143, flows through the multiple first heat exchange tubes 145, and then converges in the first confluence chamber 141 before being discharged.

[0040] Exhaust gas heat exchange channel 130: The exhaust gas heat exchange channel 130 is formed in the annular gap between the first heat exchange shell 140 and the second heat exchange shell 150. High-temperature exhaust gas enters the annular channel from the exhaust gas inlet 131 and flows out from the exhaust gas outlet 132.

[0041] During operation, the three media flow through their respective channels and exchange heat through the partition walls: the ammonia in the ammonia heat exchange channel 110 exchanges heat countercurrently with the cracked gas in the cracked gas heat exchange channel 120 and the waste gas in the waste gas heat exchange channel 130, thereby achieving cascade preheating.

[0042] Furthermore, such as Figure 2 As shown, the first heat exchange tube 145 is spiral in shape and is used for the high-temperature pyrolysis gas channel. When the gas flows in the spiral tube, a secondary flow is generated due to centrifugal force, which destroys the thermal boundary layer and enhances convective heat transfer. The second heat exchange tube 146 is straight in shape and is used for the ammonia gas channel. Ammonia gas has a lower temperature and a slower flow rate. The straight tube structure has low resistance, is not easy to clog, and is easy to process and clean.

[0043] The spiral tube structure significantly increases the heat exchange area and turbulence without increasing the tube length, making it suitable for rapid heat release from cracked gas; the straight tube structure ensures smooth ammonia flow, reduces pressure drop, and decreases pump energy consumption. The combination of the two achieves an optimized balance between heat exchange intensity and flow resistance.

[0044] This invention, by setting up independent and coupled ammonia heat exchange channel 110, cracked gas heat exchange channel 120, and waste gas heat exchange channel 130, enables the raw material ammonia to successively absorb the sensible heat of high-temperature cracked gas and combustion waste gas, forming a two-stage preheating process. This structure avoids the direct emission of high-grade heat energy, maximizes the recovery of internal waste heat, significantly reduces external heating requirements, and improves overall thermal efficiency by more than 20%.

[0045] The first heat exchange housing 140 has four chambers arranged sequentially along the axial direction (first confluence chamber 141, first heat exchange chamber 142, second heat exchange chamber 143, and second confluence chamber 144). These chambers, along with the nested second heat exchange housing 150, integrate the heat exchange channels for the three media into a single component, eliminating the need for external connecting pipelines. This compact design significantly reduces the size and weight of the device, facilitating installation in space-constrained environments such as vehicle-mounted installations.

[0046] Ammonia and cracked gas flow through different heat exchange tube bundles (ammonia flows through the second heat exchange tube 146, and cracked gas flows through the first heat exchange tube 145), forming a cross-flow counter-current pattern in the axial direction. Compared with co-flow or single heat exchange methods, the counter-flow arrangement can maintain a larger logarithmic mean temperature difference, enhance the driving force of heat transfer, and thus obtain a higher outlet preheating temperature with the same heat exchange area.

[0047] like Figure 2 As shown, the second heat exchange shell 150 is nested around the outer periphery of the first heat exchange shell 140, forming an annular exhaust gas channel. The high-temperature exhaust gas not only provides auxiliary heating to the ammonia gas in the first heat exchange chamber 142, but also serves as insulation, reducing heat loss from the first heat exchange shell 140 to the outside. This design is particularly suitable for operating conditions where the exhaust gas temperature is relatively low but still has utilization value, achieving the recovery of low-temperature heat energy and stabilizing the temperature of the ammonia gas before it enters the pyrolysis unit.

[0048] Furthermore, such as Figure 1 As shown, a booster pump 700 is provided between the cracked gas outlet 212 and the cracked gas inlet 121. The inlet of the booster pump 700 is connected to the cracked gas outlet 212 of the ammonia cracking channel 210, and the outlet is connected to the cracked gas inlet 121 of the ammonia preheating component 100. It is used to pressurize the high-temperature cracked gas discharged from the ammonia cracking channel 210 and then transport it to the cracked gas heat exchange channel 120.

[0049] The cracked gas generated in the ammonia cracking channel 210 is a high-temperature, low-pressure mixture of hydrogen and nitrogen. Due to the flow resistance inside the heat exchange channel, relying solely on the residual pressure at the cracker outlet is insufficient to ensure that the cracked gas flows through the cracked gas heat exchange channel 120 at a sufficient velocity and completes adequate heat exchange. After the booster pump 700 starts, it pressurizes the cracked gas through a pressurization mechanism such as an impeller or diaphragm, giving it sufficient kinetic energy to overcome the flow resistance of the pipeline and heat exchange tube bundle, forcibly sending the high-temperature cracked gas into the multiple first heat exchange tubes 145 of the cracked gas heat exchange channel 120. During the flow, the cracked gas undergoes high-intensity indirect wall convection heat exchange with the cold ammonia gas in the shell side through the tube wall, releasing sensible heat and cooling down before being discharged from the cracked gas outlet 122.

[0050] Furthermore, such as Figure 1 As shown, a distribution regulating valve 800 is provided between the ammonia outlet 112 and the fuel inlet 221 and ammonia inlet 211. Specifically, the ammonia outlet 112 is connected to the inlet end of the distribution regulating valve 800 via a main pipeline. The distribution regulating valve 800 has two outlet ends, wherein the first outlet end is connected to the fuel inlet 221 of the ammonia combustion chamber 220, and the second outlet end is connected to the ammonia inlet 211 of the ammonia cracking channel 210. The distribution regulating valve 800 is used to regulate the flow distribution ratio of preheated ammonia flowing from the ammonia outlet 112 between the fuel inlet 221 and the ammonia inlet 211.

[0051] After being preheated in stages by the ammonia preheating component 100, the temperature of the ammonia gas has risen to near the temperature required for the cracking reaction. The preheated ammonia gas flows out from the ammonia outlet 112 and first enters the distribution regulating valve 800. The distribution regulating valve 800 can employ a three-way proportional regulating valve structure, changing the opening ratio of the two outlets by altering the position of the valve core, thereby controlling the ammonia flow rate to the ammonia combustion chamber 220 and the ammonia cracking channel 210, respectively.

[0052] When it is necessary to increase the cracking reaction temperature or start up quickly, the distribution regulating valve 800 increases the proportion of ammonia gas to the fuel inlet 221, so that more ammonia gas mixes with air and is catalytically burned in the ammonia combustion chamber 220, releasing more heat, which is transferred to the ammonia cracking channel 210 through the partition wall to achieve rapid thermal compensation.

[0053] When the pyrolysis reaction temperature is stable and the residual heat is sufficient, the distribution regulating valve 800 reduces the proportion of ammonia gas supplied to the fuel inlet 221, and sends most of the preheated ammonia gas directly into the ammonia pyrolysis channel 210 for pyrolysis to produce hydrogen, thereby reducing combustion consumption and increasing the hydrogen production rate of the system.

[0054] When catalyst activity decreases or load fluctuates, the distribution regulating valve 800 can dynamically adjust the distribution ratio according to the controller command to maintain the best cracking efficiency.

[0055] Furthermore, the low-energy ammonia cracking hydrogen production unit also includes signal acquisition components and intelligent control components.

[0056] like Figure 1 As shown, the signal acquisition component includes the following sensors and detection units: A nitrogen oxide concentration detector 2221 is installed at the exhaust outlet 222 of the ammonia combustion chamber 220 or the exhaust outlet 132 of the exhaust heat exchange channel 130 to monitor the NOx concentration in the combustion exhaust gas in real time. Temperature sensor array 213 is disposed in the reaction zone of ammonia cracking channel 210 and distributed along the axial or radial direction to monitor the temperature distribution at different locations in the reaction zone. An air-fuel ratio sensor 2211 is installed on the fuel inlet 221 pipeline of the ammonia combustion chamber 220 to monitor the mixing ratio of ammonia and air entering the combustion chamber. Ammonia flow sensor 1111 is installed at ammonia inlet 111 of ammonia preheating component 100 to monitor the total flow rate of raw ammonia flowing through ammonia inlet 111. The differential pressure sensor 214 has two pressure measuring ends respectively set at the ammonia inlet 211 and the cracked gas outlet 212 of the ammonia cracking channel 210. It is used to monitor the pressure difference before and after the cracking reaction to reflect the blockage of the catalyst or the change of flow channel resistance. The temperature difference sensor 133 has two temperature measuring ends respectively set at the waste gas inlet 131 and waste gas outlet 132 of the waste gas heat exchange channel 130, and is used to monitor the temperature difference of the waste gas before and after entering and exiting the heat exchange channel, so as to calculate the waste heat recovery efficiency. Catalyst activity monitor 215 is installed on the inner wall of the ammonia cracking channel 210 to monitor the activity of the ammonia cracking catalyst in real time or periodically, for example by impedance spectroscopy, electrochemistry or temperature response.

[0057] The intelligent control component includes a controller module that is connected to the signal acquisition component. The control output terminals of the controller module are electrically connected to the booster pump 700, the distribution regulating valve 800, and the air compressor 410, respectively.

[0058] Temperature compensation control: When the temperature sensor array 213 detects that the real-time temperature of the reaction zone in the ammonia cracking channel 210 is lower than the preset temperature threshold, the controller module controls the distribution regulating valve 800 to increase the proportion of ammonia gas distributed to the ammonia combustion chamber 220, so that more ammonia gas participates in catalytic combustion, quickly releases heat, and transfers it to the ammonia cracking channel 210 through the partition wall to achieve rapid thermal compensation until the temperature of the reaction zone returns to the set range.

[0059] Emission control: When the nitrogen oxide concentration detector 2221 detects that the NOx concentration in the combustion exhaust gas is higher than the preset concentration threshold, the controller module adjusts the power of the air compressor 410 to change the air-fuel ratio (usually by reducing the air-fuel ratio and reducing excess oxygen), thereby suppressing NOx generation and causing the emission concentration to fall back to the acceptable range.

[0060] Activity decay compensation control: When the catalyst activity monitor 215 detects that the activity of the ammonia cracking catalyst is lower than the preset activity threshold, the controller module controls the distribution regulating valve 800 to increase the proportion of ammonia gas distributed to the ammonia combustion chamber 220, thereby increasing the temperature of the cracking reaction zone. The temperature increase is used to compensate for the decrease in cracking efficiency caused by the decrease in catalyst activity and maintain a stable hydrogen yield.

[0061] This invention comprehensively monitors flow rate, temperature, pressure difference, temperature difference, air-fuel ratio, NOx concentration, and catalyst activity using multiple sensors, forming a complete "digital twin" data pool of operating status, providing reliable input for intelligent control. The controller integrates temperature compensation, emission control, and activity compensation within the same framework, avoiding conflicts between control objectives (for example, rising temperatures may worsen NOx emissions, but this can be mitigated by adjusting the air-fuel ratio), achieving system-level synergistic optimization. Facing different stages such as start-up, steady state, sudden load changes, and catalyst aging, the control system can automatically adjust its control strategy without manual intervention, making it particularly suitable for unattended or dynamic load scenarios such as vehicle-mounted systems. Through pressure difference monitoring to warn of blockages, activity monitoring to guide maintenance, and precise temperature control to prevent overheating, it effectively extends the service life of catalysts and key components, reducing unplanned downtime.

[0062] In some other embodiments, the intelligent control component also incorporates a prediction module and a multivariate model predictive control (MPC) module.

[0063] The prediction module constructs a dynamic digital twin model of the ammonia cracking reaction based on historical operating data and real-time acquired data. This model can simulate the thermodynamic behavior and reaction kinetics of the unit under different operating conditions, and predict the optimal cracking temperature, ammonia distribution ratio, and combustion load in the current and short-term future time domains.

[0064] The MPC module is connected to the prediction module. Based on the optimal target value output by the prediction module, it performs rolling time-domain optimization on the following control variables: total ammonia flow rate, pyrolysis reactor reaction zone temperature, ammonia combustion chamber 220 intake air volume, fuel ratio (i.e., the ratio of ammonia allocated to the combustion chamber and pyrolysis unit), and exhaust gas recirculation flow rate. The MPC module aims to minimize total system energy consumption, maximize hydrogen production, and achieve optimal operational stability. Under the premise of satisfying multiple constraints such as temperature, pressure, and emissions, it generates a series of control commands.

[0065] The actuator units (including flow regulating valve / distribution regulating valve 800, booster air pump 700, air compressor 410, etc.) adjust their respective operating states in real time according to the control commands issued by the MPC module, thereby achieving the following control effects in a coordinated manner: the ammonia stage preheating temperature is precisely controllable, the temperature of the cracking reaction zone is stably maintained in the optimal range, and the waste heat recovery efficiency is maximized.

[0066] Furthermore, this invention also proposes a control method for an ammonia cracking hydrogen production device, applicable to the aforementioned low-energy-consumption ammonia cracking hydrogen production device, such as... Figure 3 As shown, the control methods include: Step S100: According to the preset hydrogen production rate, the ammonia gas is continuously fed into the ammonia heat exchange channel 110 according to the preset ammonia flow rate.

[0067] The controller calculates the required total ammonia flow rate based on the target hydrogen production (e.g., the power requirement of the corresponding fuel cell). Through closed-loop feedback from the ammonia supply assembly 300 (such as the ammonia storage tank 310 and the outlet flow valve) and the ammonia flow sensor 1111, the ammonia input flow rate is adjusted to a preset value. Ammonia enters the first heat exchange chamber 142 of the ammonia preheating assembly 100 via the ammonia inlet 111 and begins to flow through the ammonia heat exchange channel 110.

[0068] Step S200: According to the preset mixing ratio, a portion of the preheated ammonia gas is mixed with air and sent into the ammonia combustion chamber 220 for catalytic combustion, while the other portion of the preheated ammonia gas is sent into the ammonia cracking channel 210 for cracking reaction.

[0069] After being preheated in stages by the ammonia preheating component 100, the ammonia gas flows out from the ammonia outlet 112 and enters the distribution regulating valve 800. The controller calculates the ammonia ratio distributed to the ammonia combustion chamber 220 and the ammonia cracking channel 210 based on the current temperature of the cracking reaction zone, catalyst activity, and target hydrogen production. The distribution regulating valve 800 opens accordingly, directing a portion of the ammonia gas to the fuel inlet 221, while the air supply component 400 draws in air at a preset air-fuel ratio. The two gases mix in the mixing pipe and are then sent to the ammonia combustion chamber 220. The remaining ammonia gas is directly sent to the ammonia inlet 211 of the ammonia cracking channel 210.

[0070] This system enables flexible allocation of ammonia between hydrogen production and heating, ensuring a stable supply of feedstock for the cracking reaction while providing a controllable heat source for the system through catalytic combustion. Dynamic proportioning allows for adaptation to different operating conditions, avoiding energy waste or insufficient heat caused by traditional fixed allocation methods.

[0071] Step S300: The heat generated by catalytic combustion is controlled to heat the ammonia cracking channel 210, and the generated high-temperature waste gas flows through the waste gas heat exchange channel 130 to preheat and keep the ammonia in the ammonia heat exchange channel 110 warm.

[0072] The ammonia gas mixed with air fed into the ammonia combustion chamber 220 undergoes flameless catalytic combustion under the action of the ammonia combustion catalyst, releasing a large amount of heat. Since the ammonia combustion chamber 220 is enclosed in a kiln-like manner around the ammonia cracking channel 210, the combustion heat is directly conducted to the ammonia cracking channel 210 through the partition wall, maintaining the temperature of the cracking zone within a preset range. The high-temperature exhaust gas generated by combustion flows out from the exhaust gas outlet 222 and enters the exhaust gas inlet 131 of the exhaust gas heat exchange channel 130 via a pipeline. The exhaust gas heat exchange channel 130 is formed in the annular gap between the first heat exchange shell 140 and the second heat exchange shell 150. Within this channel, the exhaust gas flows counter-currently through the outer wall of the first heat exchange chamber 142, transferring heat to the ammonia gas undergoing initial preheating or insulation. The heat-exchanged exhaust gas is discharged from the exhaust gas outlet 132 and enters the exhaust gas processor 600.

[0073] Step S400: Control the high-temperature pyrolysis gas generated by the pyrolysis reaction to flow through the pyrolysis gas heat exchange channel 120 to preheat the ammonia gas in the ammonia heat exchange channel 110.

[0074] Within the ammonia cracking channel 210, preheated ammonia gas is cracked by a cracking catalyst to produce hydrogen and nitrogen, which are rich in sensible heat. The cracked gas flows out from the cracked gas outlet 212 and enters the booster pump 700 through a pipeline. The booster pump 700 pressurizes the cracked gas to a pressure sufficient to overcome the flow resistance of the heat exchange tube bundle, and then sends it into the cracked gas inlet 121 of the cracked gas heat exchange channel 120. The cracked gas enters the second heat exchange chamber 143, flows into multiple first heat exchange tubes 145, and exchanges heat with the ammonia gas in the shell side in a counter-current manner. After releasing sensible heat, it cools down and is discharged from the cracked gas outlet 122. The heated ammonia gas absorbs heat in the ammonia heat exchange channel 110, and its temperature is further increased.

[0075] Step S500: Purify the pyrolysis gas after heat exchange to obtain hydrogen.

[0076] The cooled pyrolysis gas discharged from the pyrolysis gas outlet 122 of the pyrolysis gas heat exchange channel 120 enters the gas separator 500. The gas separator 500 can employ a membrane separation unit or a pressure swing adsorption (PSA) unit. Taking membrane separation as an example: after pretreatment to remove ammonia and moisture, the pyrolysis gas enters the hollow fiber membrane module. Utilizing the small size of hydrogen molecules, hydrogen preferentially permeates through the membrane under pressure, yielding high-purity hydrogen (≥99.97%). The retained side is nitrogen-rich gas, which can be partially recycled to the combustion chamber as dilution gas or directly emitted. The purified hydrogen is supplied to the fuel cell or compressed for hydrogen storage via a buffer tank. Residual trace amounts of ammonia are treated together by the exhaust gas processor 600.

[0077] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0078] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A low-energy-consumption ammonia cracking hydrogen production device, characterized in that, include: The ammonia preheating component is equipped with an ammonia heat exchange channel, a cracked gas heat exchange channel, and a waste gas heat exchange channel. The ammonia heat exchange channel has an ammonia inlet and an ammonia outlet, the cracked gas heat exchange channel has a cracked gas inlet and a cracked gas outlet, and the waste gas heat exchange channel has a waste gas inlet and a waste gas outlet; the ammonia heat exchange channel exchanges heat with the cracked gas heat exchange channel and the waste gas heat exchange channel respectively through partition walls. An ammonia cracking combustion assembly includes an ammonia cracking channel and an ammonia combustion chamber. The ammonia cracking channel contains an ammonia cracking catalyst and has an ammonia inlet and a cracked gas outlet. The ammonia combustion chamber contains an ammonia combustion catalyst and has a fuel inlet and an exhaust gas outlet. The ammonia combustion chamber surrounds the ammonia cracking channel and exchanges heat with it through a partition wall. The ammonia outlet is connected to both the fuel inlet and the ammonia inlet. The cracked gas outlet is connected to the cracked gas inlet. The exhaust gas outlet is connected to the exhaust gas inlet. An ammonia supply assembly, connected to the ammonia inlet, is used to supply ammonia to the ammonia heat exchange channel; An air supply assembly, connected to the fuel inlet, is used to supply the air required for combustion to the ammonia combustion chamber.

2. The low-energy ammonia cracking hydrogen production device according to claim 1, characterized in that: The ammonia preheating assembly includes a first heat exchange shell and a second heat exchange shell; The first heat exchange shell is provided with a first confluence cavity, a first heat exchange cavity, a second heat exchange cavity, and a second confluence cavity arranged sequentially along the axial direction. The first heat exchange chamber is provided with a plurality of first heat exchange tubes, one end of each first heat exchange tube is connected to the second heat exchange chamber, and the other end is connected to the first confluence chamber; the second heat exchange chamber is provided with a plurality of second heat exchange tubes, one end of each second heat exchange tube is connected to the first heat exchange chamber, and the other end is connected to the second confluence chamber. The first heat exchange chamber, a plurality of second heat exchange tubes, and the second confluence chamber are sequentially connected to form the ammonia heat exchange channel. The ammonia inlet is located in the first heat exchange chamber, and the ammonia outlet is located in the second confluence chamber. The second heat exchange chamber, a plurality of first heat exchange tubes, and the first confluence chamber are sequentially connected to form the cracked gas heat exchange channel. The cracked gas inlet is located in the second heat exchange chamber, and the cracked gas outlet is located in the first confluence chamber. The second heat exchange shell is nested around the outer periphery of the first heat exchange shell and corresponds to the position of the first heat exchange cavity. The exhaust gas heat exchange channel is formed between the first heat exchange shell and the second heat exchange shell.

3. The low-energy ammonia cracking hydrogen production device according to claim 2, characterized in that: The first heat exchange tube is spiral-shaped, and the second heat exchange tube is straight-shaped.

4. The low-energy ammonia cracking hydrogen production device according to claim 1, characterized in that: The pyrolysis gas outlet is connected to a gas separator, which is used to purify the pyrolysis gas to obtain hydrogen; the waste gas outlet is connected to a waste gas processor, which is used to purify the waste gas.

5. The low-energy ammonia cracking hydrogen production device according to claim 1, characterized in that: A booster pump is provided between the cracked gas outlet and the cracked gas inlet. The booster pump is used to pressurize the cracked gas discharged from the ammonia cracking channel and then deliver it to the cracked gas heat exchange channel.

6. The low-energy-consumption ammonia cracking hydrogen production device according to claim 5, characterized in that: A distribution regulating valve is provided between the ammonia outlet and the fuel inlet and the ammonia inlet. The distribution regulating valve is used to adjust the ammonia flow rate ratio from the ammonia outlet to the fuel inlet and the ammonia inlet.

7. The low-energy ammonia cracking hydrogen production device according to claim 6, characterized in that: The air supply assembly includes an air compressor, the outlet of which is connected to the fuel inlet, and the air compressor is used to regulate the air flow rate supplied to the ammonia combustion chamber.

8. The low-energy ammonia cracking hydrogen production device according to claim 7, characterized in that: It also includes a signal acquisition component, which includes: Nitrogen oxide concentration detector, used to monitor the NOx concentration in combustion exhaust gas; A temperature sensor array is used to monitor the temperature of the reaction zone within the ammonia cracking channel; An air-fuel ratio sensor is used to monitor the mixing ratio of ammonia and air entering the combustion chamber; An ammonia flow sensor is used to monitor the flow rate of ammonia gas passing through the ammonia inlet. A differential pressure sensor is used to monitor the pressure difference between the ammonia inlet and the cracked gas outlet; A temperature difference sensor is used to monitor the temperature difference between the exhaust gas inlet and the exhaust gas outlet; A catalyst activity monitor is used to monitor the activity of the ammonia cracking catalyst.

9. The low-energy ammonia cracking hydrogen production device according to claim 8, characterized in that: It also includes an intelligent control component, which includes a controller module that is connected to the signal acquisition component. The controller module is connected to the booster pump, the distribution regulating valve, and the air compressor, respectively. The controller module is configured as follows: When the real-time temperature of the reaction zone in the ammonia cracking channel is lower than the preset temperature threshold, the proportion of ammonia gas allocated to the ammonia combustion chamber is increased to enhance catalytic combustion and achieve rapid thermal compensation. When the NOx concentration in the combustion exhaust gas is higher than a preset concentration threshold, the power of the air compressor is adjusted to change the air-fuel ratio and reduce the NOx concentration. When the activity characterization parameters of the ammonia cracking catalyst are lower than a preset threshold, the controller module adjusts the proportion of ammonia gas allocated to the ammonia combustion chamber according to the real-time temperature and ammonia conversion rate of the reaction zone in the ammonia cracking channel, so as to maintain the temperature of the reaction zone within the preset temperature range.

10. A control method for an ammonia cracking hydrogen production unit, characterized in that, The control method, applicable to the low-energy ammonia cracking hydrogen production apparatus as described in any one of claims 1 to 9, comprises: According to the preset hydrogen production rate, ammonia gas is continuously input into the ammonia heat exchange channel according to the preset ammonia flow rate. According to the preset mixing ratio, a portion of the preheated ammonia gas is mixed with air and then sent into the ammonia combustion chamber for catalytic combustion, while another portion of the preheated ammonia gas is sent into the ammonia cracking channel for cracking reaction. The heat generated by catalytic combustion is controlled to heat the ammonia cracking channel, and the resulting high-temperature waste gas flows through the waste gas heat exchange channel to preheat and keep the ammonia in the ammonia heat exchange channel warm. The high-temperature pyrolysis gas generated by the pyrolysis reaction is controlled to flow through the pyrolysis gas heat exchange channel to preheat the ammonia gas in the ammonia heat exchange channel; The pyrolysis gas after heat exchange is purified to obtain hydrogen.

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