Integrated ammonia cracking hydrogen production reactor based on energy hierarchical utilization and control method thereof

Abstract

The application discloses an integrated ammonia cracking hydrogen production reactor based on energy hierarchical utilization and a control method thereof, relates to the technical field of ammonia cracking hydrogen production, and comprises a reactor body, a high-efficiency compact ammonia-hydrogen heat exchange unit is arranged in the reactor body and forms a cold-side heat exchange channel for the flow of to-be-cracked ammonia gas and a hot-side heat exchange channel for the flow of cracked gas, which is used for preheating the to-be-cracked ammonia gas by using the residual heat carried by the cracked gas, and a silicon carbide electric heating layer is arranged at the output side of the cold-side heat exchange channel and is used for receiving the ammonia gas after the first-stage preheating. The ammonia-hydrogen heat exchange, the silicon carbide second-stage preheating and the catalytic cracking are integrated in the reactor body, the residual heat of the high-temperature cracked gas can be used for the first-stage preheating of the to-be-cracked ammonia gas, the silicon carbide electric heating layer is used for further heating the ammonia gas after the first-stage preheating, and the ammonia gas can obtain a relatively continuous temperature rising process before entering the reaction tube assembly.

Description

Technical Field

[0001] This invention relates to the field of ammonia cracking hydrogen production technology, and in particular to an integrated ammonia cracking hydrogen production reactor based on energy staged utilization and its control method. Background Technology

[0002] Hydrogen is clean, efficient, and widely applicable, but its storage and transportation typically require high pressure, low temperature, or specialized storage and transportation equipment, which limits its further application in mobile scenarios such as vehicles and ships. Ammonia has a high hydrogen storage density and a relatively mature storage and transportation system. It can be cracked to produce hydrogen and nitrogen under the action of a catalyst. Therefore, using ammonia as a hydrogen carrier and cracking it at the point of use to produce hydrogen has become an important technological direction for hydrogen energy storage, transportation, and on-site hydrogen supply. Since the ammonia cracking reaction is a strongly endothermic reaction and the reaction rate is highly sensitive to temperature changes, the reactor usually needs to simultaneously complete ammonia preheating, cracking reaction heating, and high-temperature cracking gas waste heat recovery.

[0003] For mobile ammonia cracking hydrogen production equipment, both installation space and available energy are relatively limited. While reducing the reactor volume, it is also necessary to ensure that the ammonia gas reaches a suitable temperature before entering the catalytic reaction zone and continuously replenishes the heat absorbed by the reaction during the cracking process. However, the ammonia gas heating, catalytic cracking, and cracked gas cooling occur in different temperature ranges, and the heat dissipation conditions and reaction endothermic intensity vary at different locations in the reactor. This can easily lead to insufficient connection between recovered heat and preheating requirements, insufficient heating in some reaction zones, and heat concentration in some areas, thereby increasing the external energy consumption of the reactor.

[0004] Existing ammonia cracking hydrogen production equipment typically uses a gas-to-gas heat exchanger outside the reactor to preheat the inlet ammonia gas with high-temperature cracked gas, and then provides the heat required for the catalytic reaction zone through an electric heating structure. This approach can recover some of the waste heat from the cracked gas, but the heat exchanger and reactor are usually connected by a high-temperature pipeline, resulting in heat loss during gas transport. Furthermore, the temperature of the ammonia gas after waste heat exchange may not yet reach the high-activity temperature range of the catalyst, causing the catalyst near the reaction inlet to primarily bear the burden of ammonia heating. In addition, existing electric heating structures often employ overall heating or near-uniform heating, which struggles to simultaneously accommodate differences in heat dissipation at different radial locations within the reactor and the endothermic differences resulting from the gradual cracking of ammonia along the flow direction. This easily leads to problems such as locally high temperatures, insufficient heating in some areas, and low overall energy utilization. Therefore, this paper proposes an integrated ammonia cracking hydrogen production reactor and its control method based on energy staged utilization. Summary of the Invention

[0005] The purpose of this invention is to provide an integrated ammonia cracking hydrogen production reactor based on energy staged utilization and its control method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides an integrated ammonia cracking hydrogen production reactor based on energy staged utilization, comprising: Reactor body; A high-efficiency and compact ammonia-hydrogen heat exchange unit is integrated inside the reactor body and forms a cold-side heat exchange channel for the ammonia gas to be cracked and a hot-side heat exchange channel for the cracked gas. It is used to preheat the ammonia gas to be cracked using the waste heat carried by the cracked gas. A silicon carbide electric heating layer is disposed on the output side of the cold-side heat exchange channel to receive ammonia gas that has completed the first-stage preheating and to allow the ammonia gas to pass through the silicon carbide electric heating layer for the second-stage preheating. The reaction tube assembly is disposed on the output side of the silicon carbide electric heating layer. The reaction tube assembly includes multiple reaction tubes for receiving ammonia gas that has completed secondary preheating and performing catalytic cracking. The cracked gas output side of the reaction tube assembly is connected to the heat exchange channel on the hot side. A space heating component is provided, which is correspondingly arranged with the reaction tube assembly and forms a regional heating path that provides heating radially along the reaction tube assembly and a segment heating path that provides heating axially along the reaction tube assembly, for supplementing heating according to the heat absorption requirements of the reaction at different spatial locations of the reaction tube assembly.

[0007] Preferably, one end of the reactor body is provided with: End cap, the end cap covering the end of the reactor body; Fastening screws are connected between the end cap and the reactor body to secure the end cap. An electrode base is disposed on the end cap; An ammonia inlet pipe, which is connected to the cold-side heat exchange channel, is used to introduce ammonia to be cracked into the high-efficiency compact ammonia-hydrogen heat exchange unit. A pyrolysis gas outlet pipe is connected to the heat exchange channel on the hot side and is used to discharge the pyrolysis gas that has completed heat exchange.

[0008] Preferably, the high-efficiency compact ammonia-hydrogen heat exchange unit includes alternately arranged cold runner plates and hot runner plates, the cold runner plates forming the cold-side heat exchange channel, and the hot runner plates forming the hot-side heat exchange channel, wherein the ammonia gas to be cracked and the cracked gas flow counter-currently along the cold-side heat exchange channel and the hot-side heat exchange channel, respectively; the reactor body further includes: A reactor inlet ammonia flow sensor is installed at the ammonia inlet pipe; A reactor inlet ammonia temperature sensor is installed at the ammonia inlet pipe. A heat exchanger heat inlet temperature sensor is provided, which is located between the cracked gas output side of the reaction tube assembly and the hot-side heat exchange channel. An ammonia temperature sensor at the inlet of the electric heater is provided, which is disposed between the cold-side heat exchange channel and the silicon carbide electric heating layer. A reactor outlet temperature sensor is installed at the pyrolysis gas outlet pipe.

[0009] Preferably, the reaction tube assembly includes: A support grid plate is disposed within the reactor body; Multiple reaction tubes are arranged in an array on the support grid plate; A porous ceramic carrier is disposed inside the corresponding reaction tube; A catalyst coating is disposed on the porous ceramic support for catalytic cracking of ammonia gas flowing through the reaction tube.

[0010] Preferably, the space heating component includes: A resistance wire, wherein the resistance wire is configured correspondingly to each of the reaction tubes; The multiple reaction tubes are divided into a central area and an edge area along the radial direction of the reaction tube assembly, and the resistance wires corresponding to the central area and the edge area respectively form an independent heating zone path; Each of the reaction tubes is divided into an inlet section S1, an intermediate section S2, and an outlet section S3 along the ammonia flow direction. The resistance wires corresponding to the inlet section S1, the intermediate section S2, and the outlet section S3 respectively form independent heating sections. The reactor body is also equipped with: A silicon carbide outlet ammonia temperature sensor, wherein the silicon carbide outlet ammonia temperature sensor is disposed on the output side of the silicon carbide electric heating layer; A reaction tube inlet ammonia temperature sensor is disposed between the silicon carbide electric heating layer and the reaction tube assembly; Temperature sensors for the inlet section of the reaction tube in the central region and temperature sensors for the inlet section of the reaction tube in the edge region are respectively provided for the inlet sections S1 of the central region and the edge region. Temperature sensors are provided on the wall surface of the middle section of the reaction tube in the central region and the middle section of the reaction tube in the edge region, respectively, corresponding to the middle section S2 of the central region and the edge region. Temperature sensors at the outlet sections of the reaction tubes in the central and edge regions are respectively provided for the outlet sections S3 of the central and edge regions. The temperature sensor for the pyrolysis gas at the outlet of the reaction tube in the central region and the temperature sensor for the pyrolysis gas at the outlet of the reaction tube in the edge region are respectively installed on the outlet side of the reaction tube in the central region and the edge region.

[0011] Preferably, it further includes a composite insulation component disposed on the outside of the reaction tube assembly, the composite insulation component comprising: An air insulation layer is disposed on the outside of the reaction tube assembly; An aerogel insulation layer, wherein the aerogel insulation layer covers the outside of the air insulation layer; A polyurethane foam insulation layer, wherein the polyurethane foam insulation layer covers the outside of the aerogel insulation layer; A stainless steel outer layer is provided, which covers the outside of the polyurethane foam insulation layer, for external protection of the composite insulation component.

[0012] Secondly, the present invention provides a control method for an integrated ammonia cracking hydrogen production reactor based on energy staged utilization, which is implemented as described above for an integrated ammonia cracking hydrogen production reactor based on energy staged utilization, including the following steps: Step 1: Obtain the ammonia flow rate at the reactor inlet, the ammonia temperature at the outlet of the silicon carbide electric heating layer, the temperatures of different radial regions and different axial sections of the reaction tube assembly, and the reactor outlet temperature; Step 2: Based on the reactor's startup status and the change in the inlet ammonia flow rate, determine whether the reactor is currently in a cold start condition, a stable condition, or a variable load condition. Step 3: When the reactor is in cold start condition, control the silicon carbide electric heating layer and space heating component to preheat, so that the heating position that reaches the corresponding set temperature first switches to the heat preservation state, and ammonia gas is introduced after each heating position reaches the corresponding set temperature. Step 4: When the reactor is in a stable operating condition, adjust the heating power according to the radial region and axial section of the reaction tube assembly respectively, and when the overheating condition is met in any radial region, prioritize limiting the heating power corresponding to that radial region. Step 5: When the reactor is under variable load conditions, the feedforward power of the silicon carbide electric heating layer is adjusted according to the direction of change of the inlet ammonia flow rate, and the heating power of the space heating component is adjusted according to the outlet ammonia temperature of the silicon carbide electric heating layer, the temperature of different radial regions and different axial sections. Step 6: Determine the operating condition control state based on the reactor outlet temperature and the temperatures of different radial regions and different axial sections, and control the reactor to enter the stable operating condition after the cold start condition or variable load condition meets the stability conditions.

[0013] Preferably, step 3 includes: Step 3.1: Control the silicon carbide electric heating layer and the space heating component to heat up synchronously, and obtain the detection temperatures of the silicon carbide outlet ammonia temperature sensor, the central zone reaction tube outlet cracked gas temperature sensor and the edge zone reaction tube outlet cracked gas temperature sensor respectively. Step 3.2: Compare each detected temperature with the corresponding preheating set temperature, so that the heating position that reaches the corresponding preheating set temperature first is put into the heat preservation state, and the heating position that has not reached the corresponding preheating set temperature continues to rise until all heating positions reach the corresponding preheating set temperature. Step 3.3: Turn on the ammonia input and gradually increase the inlet ammonia flow rate so that the ammonia gas passes sequentially through the high-efficiency compact ammonia-hydrogen heat exchange unit, the silicon carbide electric heating layer, and the reaction tube assembly; Step 3.4: Adjust the heating power of the silicon carbide electric heating layer and the space heating component according to the temperature of the cracked gas detected by the heat exchanger inlet temperature sensor, and end the cold start operation after the temperature of the cracked gas reaches the reaction set temperature and remains stable.

[0014] Preferably, step 4 includes: Step 4.1: When the absolute value of the change in the inlet ammonia flow rate is less than the stability threshold, the reactor is determined to be in a stable operating condition, and the temperatures of the inlet section S1, the middle section S2, and the outlet section S3 corresponding to the central and edge regions are obtained respectively. Step 4.2: Based on the deviations between the temperatures of the inlet section S1, the middle section S2, and the outlet section S3 and the corresponding set temperatures, adjust the heating power of the corresponding heating path sections respectively, and based on the deviations between the pyrolysis gas temperature at the outlet of the reaction tube in the central area and the edge area and the corresponding set outlet temperature, adjust the set temperature corresponding to the outlet section S3. Step 4.3: Compare the temperature of each axial segment in the central area and the edge area with the corresponding overheating set temperature. When the temperature of any axial segment in the central area or the edge area exceeds the corresponding overheating set temperature, limit the power reduction of the regional heating path corresponding to the radial area to which the axial segment belongs. Step 4.4: Control the execution priority of the power reduction limit to be higher than the heating regulation priority of the heating path segment, so as to prioritize the execution of the power reduction limit when there is a conflict between radial overheat protection and axial segmented heating.

[0015] Preferably, step 5 includes: Step 5.1: When the absolute value of the change in the inlet ammonia flow rate is greater than the variable load threshold, it is determined that the reactor is in a variable load condition, and the reactor is in a loading state or a unloading state according to the direction of the change in the inlet ammonia flow rate. Step 5.2: When the inlet ammonia flow rate increases, increase the input power of the silicon carbide electric heating layer; when the inlet ammonia flow rate decreases, decrease the input power of the silicon carbide electric heating layer to perform feedforward temperature regulation on the ammonia that has completed the first stage of preheating. Step 5.3: Compare the outlet ammonia temperature of the silicon carbide electric heating layer with the preheating set temperature, and adjust the input power of the silicon carbide electric heating layer according to the temperature difference between the two. At the same time, adjust the heating power of the regional heating path and the segment heating path according to the temperature difference of different radial regions and different axial sections respectively. Step 5.4: Obtain the reactor outlet temperature, and when the deviation between the reactor outlet temperature and the set outlet temperature is less than the outlet temperature stabilization threshold, end the variable load condition and control the reactor to enter the stable condition.

[0016] The technical effects and advantages of this invention are as follows: 1. This invention integrates ammonia-hydrogen heat exchange, silicon carbide secondary preheating, and catalytic cracking within the reactor body. This allows the waste heat from the high-temperature cracked gas to be used for primary preheating of the ammonia to be cracked, and the silicon carbide electric heating layer further supplements the heat of the ammonia after primary preheating, ensuring a relatively continuous heating process for the ammonia before it enters the reaction tube assembly. Compared to using an external heat exchanger and overall electric heating of the reaction area, this method reduces heat loss of the high-temperature cracked gas during external pipeline transportation and avoids the reaction zone bearing excessive raw material heating load. It also connects waste heat recovery, preheating before reaction, and reaction endothermic compensation, thereby reducing ineffective heat supply and improving the utilization of heat inside the reactor. 2. This invention utilizes a silicon carbide electric heating layer to directly preheat ammonia gas that has undergone waste heat preheating in a secondary stage. This ensures that the ammonia gas approaches the corresponding reaction temperature before entering the porous ceramic support and catalyst coating area, reducing the situation where the inlet area of ​​the reaction tube is mainly used for heating ammonia gas and fails to fully participate in catalytic cracking. This allows the inlet section of the reaction tube to quickly establish an effective reaction state, increases the catalyst participation in the inlet area, improves the problem of uneven catalyst utilization within the reaction tube, and provides conditions for reducing the length of inefficient catalyst beds and controlling the overall size of the reactor. 3. This invention adjusts the heating supply according to the differences in heat dissipation in different radial regions of the reaction tube assembly and the differences in heat absorption in different axial sections. When local overheating conditions are reached, the heating power of the corresponding region is preferentially limited. Simultaneously, when the load changes, the silicon carbide electric heating layer is first adjusted according to the inlet ammonia flow rate, and then the heating power of the reaction zone is corrected. This reduces the temperature deviation between the central and edge regions, and between the inlet and outlet sections, minimizing local overheating, insufficient local heating, and delayed heat replenishment during load changes. This ensures that the reactor maintains a relatively reasonable temperature distribution and heating state during cold start-up, stable operation, and load changes. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the integrated ammonia cracking hydrogen production reactor of the present invention; Figure 2 For the present invention Figure 1 Partial sectional view; Figure 3 This is a schematic diagram of the gas flow direction and reaction segmentation of the present invention; Figure 4 This is a schematic diagram of the high-efficiency and compact ammonia-hydrogen heat exchange unit structure of the present invention; Figure 5 This is a schematic diagram of the cross-sectional structure of the reaction tube of the present invention; Figure 6 This is a schematic diagram of the composite thermal insulation structure of the present invention; Figure 7 This is a schematic diagram of the reactor energy utilization of the present invention; Figure 8 This is a flowchart of the cold start control process of the present invention; Figure 9 This is a flowchart of the stable operating condition control of the present invention; Figure 10 This is a flowchart of the variable load condition control of the present invention.

[0018] In the attached diagram: 1. Fastening screw; 2. Reactor inlet ammonia flow sensor; 3. Reactor inlet ammonia temperature sensor; 4. Ammonia inlet pipe; 5. Cracking gas outlet pipe; 6. Reactor outlet temperature sensor; 7. End cap; 8. Electrode base; 9. High-efficiency compact ammonia-hydrogen heat exchange unit; 10. Heat exchanger heat flow inlet temperature sensor; 11. Electric heater inlet ammonia temperature sensor; 12. Air insulation layer; 13. Aerogel insulation layer; 14. Polyurethane foam insulation layer; 15. Stainless steel outer layer; 16. Support grid plate; 17. Reaction tube; 18. Porous ceramic carrier; 19. Silicon carbide electric heating layer; 20. Silicon carbide outlet ammonia temperature sensor; 21. Reaction tube inlet ammonia temperature sensor; 22. Reactor body; 23. Temperature sensor at the inlet section of the central reaction tube; 24. Temperature sensor at the inlet section of the edge reaction tube; 25. Temperature sensor on the wall of the middle section of the central reaction tube; 26. Temperature sensor at the middle section of the edge reaction tube; 27. Temperature sensor at the outlet section of the central reaction tube; 28. Temperature sensor at the outlet section of the edge reaction tube; 29. ​​Temperature sensor for the cracked gas at the outlet of the central reaction tube; 30. Temperature sensor for the cracked gas at the outlet of the edge reaction tube; 31. Resistance wire; 32. Catalyst coating. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides, for example Figures 1-10 The integrated ammonia cracking hydrogen production reactor shown includes a reactor body 22. A high-efficiency and compact ammonia-hydrogen heat exchange unit 9 is integrated inside the reactor body 22, forming a cold-side heat exchange channel for the ammonia to be cracked and a hot-side heat exchange channel for the cracked gas. This channel utilizes the waste heat carried by the cracked gas to perform primary preheating of the ammonia to be cracked. A silicon carbide electric heating layer 19 is disposed on the output side of the cold-side heat exchange channel to receive the ammonia that has completed primary preheating and to allow the ammonia to pass through the silicon carbide electric heating layer 19 for secondary preheating. A reaction tube assembly is disposed on the output side of the silicon carbide electric heating layer 19. The reaction tube assembly includes multiple reaction tubes 17 to receive the ammonia that has completed secondary preheating and to perform catalytic cracking. The cracked gas output side of the reaction tube assembly is connected to the hot-side heat exchange channel. A spatial heating component is disposed corresponding to the reaction tube assembly, forming a regional heating path that provides heating radially along the reaction tube assembly and a segmental heating path that provides heating axially along the reaction tubes 17. This component supplements the heating according to the heat absorption requirements of the reaction at different spatial locations of the reaction tube assembly.

[0021] In one embodiment, after the ammonia gas to be cracked enters the high-efficiency compact ammonia-hydrogen heat exchange unit 9, it undergoes indirect heat exchange with the high-temperature cracked gas output from the reaction tube assembly. Part of the heat carried by the high-temperature cracked gas is transferred to the ammonia gas to be cracked, thus completing the first-stage preheating of the ammonia gas. Since the high-efficiency compact ammonia-hydrogen heat exchange unit 9 is integrated inside the reactor body 22, the high-temperature cracked gas can directly participate in heat exchange after leaving the reaction tube assembly, reducing heat loss along the flow path of the high-temperature cracked gas within the external connecting pipes, and allowing the waste heat generated by the cracking reaction to be preferentially used for heating the ammonia gas subsequently entering the reactor.

[0022] The ammonia gas, after primary preheating, enters the silicon carbide electric heating layer 19. The silicon carbide electric heating layer 19 can employ a porous silicon carbide heating element. Upon energization, heat is generated by the porous silicon carbide heating element. The ammonia gas passes through the pores inside the porous silicon carbide heating element and directly contacts its heating surface for heat exchange, thus completing the secondary preheating. Primary preheating primarily utilizes the waste heat from the cracked gas to achieve the basic temperature rise of the ammonia gas. Secondary preheating utilizes electrical energy to supplement the remaining temperature rise required for the ammonia gas to enter the catalytic reaction, avoiding the direct use of high-grade electrical energy to bear the entire preheating load.

[0023] Ammonia gas, after undergoing secondary preheating, enters multiple reaction tubes 17 and undergoes a cracking reaction under the action of a catalyst, generating cracked gas containing hydrogen and nitrogen. By performing secondary preheating before the ammonia gas enters the reaction tube assembly, the inlet ammonia gas is kept in a higher reaction temperature range, reducing the situation where the catalyst in the reaction tube inlet region mainly serves to raise the temperature of the ammonia gas without fully participating in the cracking reaction, thus enabling the reaction tube inlet region to quickly establish an effective catalytic cracking state.

[0024] Ammonia continuously absorbs heat during its cracking reaction within reaction tube 17. The space heating component replenishes heat according to the heating needs of different spatial locations within the reaction tube assembly. The central location of the reaction tube assembly is affected by both thermal radiation and heat transfer from the surrounding reaction tubes, resulting in a different heat accumulation state compared to the edge locations. Simultaneously, as ammonia flows along reaction tube 17, the degree of reaction and the intensity of heat absorption also change in the inlet, middle, and outlet regions. The space heating component replenishes heat to different radial and axial sections, ensuring that locations with stronger heat absorption receive timely heating and minimizing excessive heating in areas with reduced heat absorption or where heat easily accumulates.

[0025] After leaving the reaction tube assembly, the high-temperature cracked gas returns to the efficient and compact ammonia-hydrogen heat exchange unit 9, transferring its residual heat to the ammonia gas to be cracked that subsequently enters the reactor. The cracked gas then exits the reactor. Thus, a continuous energy utilization process is formed inside the reactor, consisting of primary preheating with residual heat from the cracked gas, secondary preheating with the silicon carbide electric heating layer 19, catalytic cracking of the reaction tube assembly, and supplementary heating by the space heating assembly according to spatial location.

[0026] Through the above structure and working process, the waste heat from the cracked gas, the electrical energy required for the secondary preheating of ammonia, and the supplementary electrical energy required for the catalytic cracking process can be allocated to the corresponding heating and reaction stages, reducing the heat loss caused by the separate setting of the heat exchange unit and the reaction zone; at the same time, it ensures that the ammonia reaches a suitable reaction temperature before entering the reaction tube assembly, reducing the situation where the catalyst in the inlet area bears ineffective heating; and by supplementing heat to different radial regions and different axial sections, the heat supply distribution is matched with the differences in heat dissipation and reaction endothermic differences inside the reactor, thereby reducing local insufficient heating, heat accumulation and ineffective heating, improving the effective utilization of the catalyst and the overall energy utilization efficiency of the reactor.

[0027] Furthermore, an end cap 7 is provided at one end of the reactor body 22, covering the end of the reactor body 22. A fastening screw 1 is connected between the end cap 7 and the reactor body 22 to fix the end cap 7. An electrode base 8 is provided on the end cap 7. An ammonia gas inlet pipe 4 is connected to the cold side heat exchange channel to introduce the ammonia gas to be cracked into the high-efficiency compact ammonia-hydrogen heat exchange unit 9. A cracked gas outlet pipe 5 is connected to the hot side heat exchange channel to discharge the cracked gas that has completed heat exchange.

[0028] In one embodiment, during the aforementioned ammonia preheating, catalytic cracking, and waste heat recovery process of the cracked gas, one end of the reactor body 22 serves as a centralized installation end for gas inlet, gas outlet, and power supply to the heating structure. The end cap 7 seals the end of the reactor body 22 and is fixedly connected to it by fastening screws 1. When it is necessary to inspect or maintain the internal structure of the reactor, the end cap 7 can be removed after removing the fastening screws 1 to expose the corresponding end area.

[0029] Electrode base 8 is mounted on end cap 7 and can be used to install power supply terminals that connect to silicon carbide electric heating layer 19 and space heating components, enabling the heating structure inside the reactor to be electrically connected through the end. Ammonia gas enters the cold side heat exchange channel through ammonia gas inlet pipe 4, and the cracked gas after heat exchange is discharged through cracked gas outlet pipe 5. Ammonia gas inlet pipe 4, cracked gas outlet pipe 5 and electrode base 8 are centrally arranged at the end where end cap 7 is located, facilitating the connection of external gas paths and power supply lines.

[0030] With the above configuration, the end cap 7 can take into account both the sealing of the reactor end and the maintenance of the internal structure. Ammonia gas inlet, cracked gas outlet and power supply for heating structure are all completed in a centralized manner at the reactor end, thereby reducing the assembly inconvenience caused by the dispersed arrangement of external interfaces and facilitating the subsequent disassembly and maintenance of the reactor.

[0031] Furthermore, the efficient and compact ammonia-hydrogen heat exchange unit 9 includes alternately arranged cold runner plates and hot runner plates. The cold runner plates form a cold-side heat exchange channel, and the hot runner plates form a hot-side heat exchange channel. The ammonia gas to be cracked and the cracked gas flow counter-currently along the cold-side heat exchange channel and the hot-side heat exchange channel, respectively. The reactor body 22 also includes: Ammonia flow sensor 2 at reactor inlet is installed at ammonia inlet pipe 4. Ammonia temperature sensor 3 at reactor inlet is installed at ammonia inlet pipe 4. The heat exchanger heat inlet temperature sensor 10 is located between the cracked gas output side and the hot side heat exchange channel of the reaction tube assembly. The ammonia temperature sensor 11 at the inlet of the electric heater is located between the cold-side heat exchange channel and the silicon carbide electric heating layer 19. Reactor outlet temperature sensor 6 is located at the pyrolysis gas outlet pipe 5.

[0032] In one embodiment, based on the aforementioned end-entry / exit gas structure, the ammonia gas to be cracked enters the high-efficiency compact ammonia-hydrogen heat exchange unit 9 through the ammonia gas inlet pipe 4. The ammonia gas to be cracked enters through the inlet of one end plate of the heat exchange unit, and after radial distribution, flows into the cold-side heat exchange channels formed by the cold runner plates, and flows out circumferentially from the other end plate after completing heat exchange; the high-temperature cracked gas output from the reaction tube assembly enters the hot-side heat exchange channels formed by the hot runner plates from the center of the other end plate, and flows out from the center of one end plate. Thus, the ammonia gas to be cracked and the high-temperature cracked gas are kept isolated from each other in adjacent plates and flow in opposite directions.

[0033] Alternating cold and hot runner plates ensure that the high-temperature cracked gas continuously transfers heat to the ammonia gas to be cracked in the adjacent cold-side heat exchange channel during its flow. Countercurrent flow maintains a relatively stable temperature difference between the two gases within the heat exchange path, preventing concentrated heat exchange in localized areas. This extends the effective heat exchange process within the limited reactor space and improves the recovery of waste heat from the high-temperature cracked gas.

[0034] The reactor inlet ammonia flow sensor 2 and reactor inlet ammonia temperature sensor 3 collect the ammonia flow rate and initial temperature entering the reactor, respectively; the electric heater inlet ammonia temperature sensor 11 collects the ammonia temperature after the first-stage preheating, which is used to reflect the cold-side heat exchange status of the efficient and compact ammonia-hydrogen heat exchange unit 9. The heat exchanger heat flow inlet temperature sensor 10 collects the temperature of the cracked gas output from the reaction tube assembly before entering the hot-side heat exchange channel, and the reactor outlet temperature sensor 6 collects the temperature of the cracked gas after heat exchange.

[0035] By comparing the temperatures of the ammonia gas to be cracked before and after heat exchange with those of the cracked gas, the actual heat exchange state of the efficient and compact ammonia-hydrogen heat exchange unit 9 can be determined, providing a temperature basis for subsequent heating regulation of the silicon carbide electric heating layer 19. This structure allows the waste heat of the high-temperature cracked gas to be directly transferred to the ammonia gas to be cracked inside the reactor, improving the primary preheating effect while reducing heat loss caused by external pipeline transportation and lowering the electrical energy required for subsequent secondary preheating.

[0036] Furthermore, the reaction tube assembly includes a support grid plate 16 disposed within the reactor body 22, multiple reaction tubes 17 arranged in an array on the support grid plate 16, a porous ceramic carrier 18 disposed within the corresponding reaction tube 17, and a catalyst coating 32 disposed on the porous ceramic carrier 18 for catalytic cracking of ammonia flowing through the reaction tube 17.

[0037] In one embodiment, after the ammonia gas to be cracked has completed secondary preheating, the ammonia gas enters the reaction tube assembly from the output side of the silicon carbide electric heating layer 19. The support grid plate 16 provides array support for multiple reaction tubes 17, so that each reaction tube 17 maintains a relatively stable arrangement within the reactor body 22, and allows the ammonia gas after secondary preheating to be distributed to different reaction tubes 17 for cracking reaction.

[0038] After ammonia enters the reaction tube 17, it flows along the pores of the porous ceramic support 18 and comes into contact with the catalyst coating 32 disposed on the surface of the porous ceramic support 18. The porous ceramic support 18 provides a stable adhesion base for the catalyst coating 32 on the one hand, and on the other hand, it uses its internal pores to form a gas flow path, increasing the contact range between ammonia and the catalyst coating 32, so that ammonia gradually decomposes into hydrogen and nitrogen as it flows through the reaction tube 17.

[0039] Since the ammonia gas entering the reaction tube assembly has been preheated in two stages by the high-efficiency compact ammonia-hydrogen heat exchange unit 9 and the silicon carbide electric heating layer 19, the porous ceramic carrier 18 and catalyst coating 32 at the inlet of the reaction tube 17 can reach an effective reaction state more quickly, reducing the situation where the catalyst in the inlet area mainly undertakes the heating of ammonia gas and does not fully participate in the cracking reaction.

[0040] With the above structure, multiple reaction tubes 17 can form parallel catalytic cracking channels in a limited space. The support grid plate 16 ensures the installation stability of the reaction tube array. The porous ceramic carrier 18 and the catalyst coating 32 work together to improve the effective contact between ammonia and the catalyst, thereby shortening the inefficient reaction zone, improving the effective utilization rate of the catalyst and the overall cracking capacity of the reaction tube assembly.

[0041] Furthermore, the space heating component includes a resistance wire 31, which is correspondingly arranged with each reaction tube 17; the multiple reaction tubes 17 are divided into a central area and an edge area along the radial direction of the reaction tube assembly, and the resistance wires 31 corresponding to the central area and the edge area respectively form an independent heating zone path; each reaction tube 17 is divided into an inlet section S1, a middle section S2 and an outlet section S3 along the ammonia flow direction, and the resistance wires 31 corresponding to the inlet section S1, the middle section S2 and the outlet section S3 respectively form an independent heating section path. The reactor body 22 is also equipped with a silicon carbide outlet ammonia temperature sensor 20, which is located on the output side of the silicon carbide electric heating layer 19. The reaction tube inlet ammonia temperature sensor 21 is located between the silicon carbide electric heating layer 19 and the reaction tube assembly. The inlet section temperature sensor 23 of the central reaction tube and the inlet section temperature sensor 24 of the edge reaction tube are respectively located at the inlet section S1 of the central and edge zones. The wall temperature sensor 25 of the middle section of the central reaction tube and the middle section temperature sensor 26 of the edge reaction tube are respectively located at the middle section S2 of the central and edge zones. The outlet section temperature sensor 27 of the central reaction tube and the outlet section temperature sensor 28 of the edge reaction tube are respectively located at the outlet section S3 of the central and edge zones. The outlet cracked gas temperature sensor 29 of the central reaction tube and the outlet cracked gas temperature sensor 30 of the edge reaction tube are respectively located at the outlet side of the reaction tube 17 in the central and edge zones.

[0042] In one embodiment, ammonia continuously absorbs heat during catalytic cracking within the reaction tube 17, and the space heating component supplements heat according to the radial position of the reaction tube assembly and the direction of ammonia flow. Resistance wires 31 are correspondingly arranged to each reaction tube 17 and can be segmented along the axial direction of the reaction tube 17. Each segment of resistance wire 31 is connected to a corresponding power supply circuit and power regulator, allowing the heating power of different radial and axial sections to be individually adjusted.

[0043] Multiple reaction tubes 17 are radially divided into a central region and an edge region. In this embodiment, the central region may have seven reaction tubes 17, and the edge region may have twelve reaction tubes 17; the specific number can be adjusted according to the reactor size and hydrogen production rate. The reaction tubes 17 in the central region are affected by the combined heat transfer and thermal radiation from the surrounding reaction tubes, making it relatively easy for heat to accumulate; the reaction tubes 17 in the edge region are closer to the outside of the reactor, resulting in relatively more heat loss. Therefore, the resistance wires 31 corresponding to the central region and the edge region form independent regional heating paths, allowing the two regions to use different heating powers, avoiding overheating in the central region or insufficient heating in the edge region due to continuous heating at the same power.

[0044] Each reaction tube 17 is divided into an inlet section S1, an intermediate section S2, and an outlet section S3 along the ammonia flow direction. The inlet section S1 has a higher ammonia concentration, resulting in greater heat absorption in the initial stage of the cracking reaction. As the ammonia flows towards the intermediate section S2 and the outlet section S3, the ammonia gradually cracks, and the degree of reaction and heat absorption requirements change accordingly. The resistance wires 31 corresponding to the inlet section S1, intermediate section S2, and outlet section S3 each form an independent heating path, enabling the inlet section S1 to promptly replenish the heat required for the strongly endothermic reaction, and allowing the intermediate section S2 and outlet section S3 to adjust their heating according to the corresponding temperature conditions, reducing excessive heat supply in the later stages of the reaction.

[0045] A silicon carbide outlet ammonia temperature sensor 20 detects the temperature of ammonia gas leaving the silicon carbide electric heating layer 19. A reaction tube inlet ammonia temperature sensor 21 detects the temperature of ammonia gas before it enters the reaction tube assembly, thereby confirming whether the ammonia gas after secondary preheating meets the temperature requirements for entering the catalytic reaction zone. Temperature sensors 23 and 24 at the inlet of the central and edge zones of the reaction tube detect the temperatures of the inlet sections S1 and S1, respectively. Temperature sensors 25 and 26 at the middle section of the central and edge zones of the reaction tube detect the temperatures of the middle section S2. Temperature sensors 27 and 28 at the outlet of the central and edge zones of the reaction tube detect the temperatures of the outlet section S3. Temperature sensors 29 and 30 at the outlet of the central and edge zones of the reaction tube detect the temperatures of the cracked gas output from the two radial zones, reflecting the reaction state of the ammonia gas after passing through each reaction tube 17.

[0046] During operation, the data collected by each temperature sensor corresponds to the respective regional heating path and section heating path. When the temperature of a certain radial area is too low, the heating power of the corresponding resistance wire 31 in that area can be increased; when the temperature of a certain axial section deviates from the set range, the heating power of the corresponding resistance wire 31 in that section can be adjusted independently without needing to simultaneously change the heating status of other areas or sections.

[0047] Through the above structure, the radial heat dissipation difference and axial reaction heat absorption difference of the reaction tube assembly are respectively mapped to different heating paths and temperature detection positions. This enables the space heating assembly to provide differentiated heating to the central area where heat easily accumulates, the edge area where heat is lost more, and the inlet section S1, the middle section S2, and the outlet section S3 with different heat absorption degrees. This reduces local overheating and local underheating, reduces ineffective power consumption, and allows the catalyst to continuously participate in the ammonia cracking reaction within a more suitable temperature range.

[0048] Furthermore, it also includes a composite insulation component disposed on the outside of the reaction tube assembly. The composite insulation component includes an air insulation layer 12 disposed on the outside of the reaction tube assembly, an aerogel insulation layer 13 covering the outside of the air insulation layer 12, a polyurethane foam insulation layer 14 covering the outside of the aerogel insulation layer 13, and a stainless steel outer layer 15 covering the outside of the polyurethane foam insulation layer 14, for external protection of the composite insulation component.

[0049] In one embodiment, during the process of ammonia catalytic cracking and segmented heating in the reaction tube assembly, a composite insulation component is installed on the outside of the reaction tube assembly to reduce heat transfer from the reaction zone to the outside of the reactor. Since the temperature near the reaction tube assembly is high and gradually decreases radially outward, the composite insulation component uses multiple layers of different materials arranged sequentially to ensure that each insulation material is within its applicable temperature range.

[0050] The air insulation layer 12 is located on the side close to the reaction tube assembly and forms an air insulation area between the reaction tube assembly and the outer insulation material to reduce the heat conduction path formed by the continuous solid structure. The aerogel insulation layer 13 uses its low thermal conductivity to absorb the heat transferred outward by the air insulation layer 12, further increasing the radial thermal resistance.

[0051] The polyurethane foam insulation layer 14 is located in the relatively cooler outer area to further reduce heat transfer to the outside of the reactor. The stainless steel outer layer 15 provides a protective covering for the air insulation layer 12, the aerogel insulation layer 13, and the polyurethane foam insulation layer 14, reducing the impact of collisions, compression, or external environmental factors on the insulation materials during transportation, installation, and use.

[0052] The contact interfaces between each insulation layer can also form corresponding contact thermal resistance, so that when heat is transferred from the reaction tube assembly to the outside, it passes through the air insulation layer 12, the aerogel insulation layer 13 and the polyurethane foam insulation layer 14 in sequence, avoiding a single insulation material from bearing a large temperature range and the entire insulation load at the same time.

[0053] Through the above structure, the air insulation layer 12 can be used to reduce continuous heat conduction in the high-temperature area, the aerogel insulation layer 13 can be used to improve the heat insulation capacity of the middle area, and the polyurethane foam insulation layer 14 can be used to further reduce heat dissipation in the outer layer. This allows different insulation materials to play a continuous role under the condition of gradually decreasing radial temperature, thereby reducing heat loss in the reaction zone, reducing the energy required for the space heating component to maintain the reaction temperature, and ensuring the structural stability of the composite insulation component by the stainless steel outer layer 15.

[0054] A control method for an integrated ammonia cracking hydrogen production reactor based on energy staged utilization, comprising the following steps: Step 1: Obtain the ammonia flow rate at the reactor inlet, the ammonia temperature at the outlet of the silicon carbide electric heating layer 19, the temperatures of different radial regions and different axial sections of the reaction tube assembly, and the reactor outlet temperature. Step 2: Determine whether the reactor is currently in cold start, stable operation, or variable load operation based on the reactor's startup status and the change in inlet ammonia flow rate. Step 3: When the reactor is in cold start condition, control the silicon carbide electric heating layer 19 and the space heating component to preheat, so that the heating position that reaches the corresponding set temperature first switches to the heat preservation state, and ammonia gas is introduced after each heating position reaches the corresponding set temperature. Step 4: When the reactor is in a stable operating condition, adjust the heating power according to the radial and axial sections of the reaction tube assembly, and when the superheating condition is met in any radial region, prioritize limiting the heating power corresponding to that radial region. Step 5: When the reactor is under variable load conditions, the feedforward power of the silicon carbide electric heating layer 19 is adjusted according to the direction of change of the inlet ammonia flow rate, and the heating power of the space heating component is adjusted according to the outlet ammonia temperature of the silicon carbide electric heating layer 19, the temperature of different radial regions and different axial sections. Step 6: Determine the operating condition control state based on the reactor outlet temperature and the temperatures of different radial regions and different axial sections, and control the reactor to enter the stable operating condition after the cold start condition or variable load condition meets the stability conditions.

[0055] In one embodiment, the electronic control module is connected to the reactor inlet ammonia flow sensor 2, the silicon carbide outlet ammonia temperature sensor 20, the temperature sensors corresponding to the central and edge zones, the reactor outlet temperature sensor 6, the silicon carbide electric heating layer 19, and the space heating assembly. During reactor operation, the electronic control module continuously receives the inlet ammonia flow rate, the outlet ammonia temperature of the silicon carbide electric heating layer 19, the temperatures of different radial and axial sections of the reaction tube assembly, and the reactor outlet temperature, and uses this data as the basis for judging operating conditions and adjusting heating.

[0056] When the reactor starts operating from a shutdown state, the electronic control module identifies the current state as a cold start condition and controls the silicon carbide electric heating layer 19 and the space heating components to preheat. Due to differences in the materials, heating conditions, and heat dissipation conditions of the silicon carbide electric heating layer 19, the central reaction tube, and the edge reaction tube, the time it takes for each heating location to reach the set temperature may differ. The electronic control module reduces the heating power of the heating location that reaches the corresponding set temperature first and maintains it within the set temperature range. Heating locations that have not yet reached the set temperature continue to heat up until all heating locations are preheated before ammonia gas is introduced. This prevents heat accumulation in the locations that have already heated up while waiting for other locations to heat up.

[0057] After ammonia gas is introduced, the electronic control module gradually increases the inlet ammonia flow rate and adjusts the heating power of the silicon carbide electric heating layer 19 and the space heating component based on the outlet ammonia temperature of the silicon carbide electric heating layer 19, the temperature of each area of ​​the reaction tube assembly, and the reactor outlet temperature. When the inlet ammonia flow rate remains within a relatively stable range and the reactor outlet temperature meets the corresponding operating requirements, the reactor is switched to stable operating conditions.

[0058] Under stable operating conditions, the electronic control module adjusts the heating power of different radial regions and axial sections of the reaction tube assembly, ensuring that the central region, edge region, and each axial section receive the appropriate heat according to their respective temperature conditions. When any radial region reaches overheating conditions, the electronic control module prioritizes limiting the heating power corresponding to that radial region and stops executing normal heating commands that might raise the temperature of that region. Normal zoned and segmented adjustment is resumed only after the overheating condition is resolved.

[0059] When the change in inlet ammonia flow exceeds the load variation judgment range, the electronic control module switches the reactor to a load variation mode. When the inlet ammonia flow increases, the input power of the silicon carbide electric heating layer 19 is increased first, so that the secondary preheating zone can replenish the heat required for the increased ammonia flow in advance. When the inlet ammonia flow decreases, the input power of the silicon carbide electric heating layer 19 is decreased first, to prevent the preheating zone from continuing to accumulate heat after the gas flow decreases. After completing the feedforward power adjustment, the heating power of the space heating component is adjusted according to the outlet ammonia temperature of the silicon carbide electric heating layer 19 and the temperatures of different radial and axial sections.

[0060] The electronic control module determines the operating status after load change based on the reactor outlet temperature and the temperature at various locations in the reaction zone. When the reactor outlet temperature returns to the set range and the temperatures in different radial and axial regions tend to stabilize, the load change condition ends and the system re-enters the stable operating condition, thus forming a continuous state transition between cold start, stable operation, and load change regulation.

[0061] Through the above control process, the heating progress of different heating locations can be coordinated during cold start, radial overheat protection and axial reaction heating can be taken into account during stable operation, and the secondary preheating zone can respond first and the reaction zone can complete the segmented correction when the load changes, thereby reducing local overheating, heating lag and ineffective energy input, so that the energy stage utilization structure of the reactor can maintain stable operation under different operating conditions.

[0062] If the stability threshold is less than or equal to the load variation threshold, and the absolute value of the change in the inlet ammonia flow rate is between the stability threshold and the load variation threshold, or equal to the corresponding threshold, the previous operating condition of the reactor should be kept unchanged to reduce the frequent switching of operating conditions caused by the fluctuation of the inlet ammonia flow rate near the threshold.

[0063] Furthermore, step 3 includes: Step 3.1: Control the silicon carbide electric heating layer 19 and the space heating component to heat up synchronously, and obtain the detection temperatures of the silicon carbide outlet ammonia temperature sensor 20, the central zone reaction tube outlet cracked gas temperature sensor 29 and the edge zone reaction tube outlet cracked gas temperature sensor 30 respectively. Step 3.2: Compare each detected temperature with the corresponding preheating set temperature, so that the heating position that reaches the corresponding preheating set temperature first is put into the heat preservation state, and the heating position that has not reached the corresponding preheating set temperature continues to rise until all heating positions reach the corresponding preheating set temperature. Step 3.3: Turn on the ammonia input and gradually increase the inlet ammonia flow rate so that the ammonia passes through the high-efficiency compact ammonia-hydrogen heat exchange unit 9, the silicon carbide electric heating layer 19 and the reaction tube assembly in sequence. Step 3.4: Adjust the heating power of the silicon carbide electric heating layer 19 and the space heating component according to the temperature of the cracked gas detected by the heat exchanger inlet temperature sensor 10, and end the cold start operation after the temperature of the cracked gas reaches the reaction set temperature and remains stable.

[0064] In one embodiment, when the reactor is in cold start condition, the electronic control module controls the silicon carbide electric heating layer 19 and the space heating component to heat up synchronously, and obtains the detection temperatures of the silicon carbide outlet ammonia temperature sensor 20, the central zone reaction tube outlet cracked gas temperature sensor 29 and the edge zone reaction tube outlet cracked gas temperature sensor 30, respectively, to determine the preheating status of the secondary preheating zone, the central zone and the edge zone.

[0065] The electronic control module compares each detected temperature with its corresponding preheating set temperature. When any heating location reaches its set preheating temperature first, the heating power of that location is reduced to maintain it within the set temperature range; heating locations that have not yet reached their set preheating temperature continue to heat up until all heating locations are preheated. This process avoids localized overheating caused by the earlier-reaching areas continuing to heat up when different areas heat up at different rates.

[0066] After preheating at each heating location, ammonia gas input is initiated and the inlet ammonia gas flow rate is gradually increased. The ammonia gas sequentially passes through the high-efficiency compact ammonia-hydrogen heat exchange unit 9, the silicon carbide electric heating layer 19, and the reaction tube assembly. The electronic control module adjusts the heating power of the silicon carbide electric heating layer 19 and the space heating assembly based on the temperature changes generated after the ammonia gas is introduced.

[0067] When the temperature of the pyrolysis gas detected by the heat exchanger inlet temperature sensor 10 reaches the reaction set temperature and remains stable, the cold start condition ends and the system enters the stable condition. This ensures that each heating point reaches its corresponding operating temperature before ammonia is introduced, reducing the impact of insufficient local temperature or temperature overshoot on the catalytic cracking state during the cold start process.

[0068] In this embodiment, T pre T represents the preheating set temperature of the silicon carbide electric heating layer 19. cra T represents the preheating set temperature of the reaction zone. sic_out The temperature detected by the silicon carbide outlet ammonia temperature sensor 20 is represented by T. cia_out1 and Tcia_out2 T represents the detection temperatures of the pyrolysis gas temperature sensor 29 at the outlet of the central reaction tube and the pyrolysis gas temperature sensor 30 at the outlet of the edge reaction tube, respectively. out The temperature detected by the heat exchanger inlet temperature sensor 10 is represented by T. n The reaction set temperature is indicated by ε1, ε2 and ε3, which represent the allowable temperature deviation for the corresponding temperature judgment. Their specific values ​​can be preset according to the reactor specifications, catalyst working temperature and operating conditions.

[0069] Furthermore, step 4 includes: Step 4.1: When the absolute value of the change in the inlet ammonia flow rate is less than the stability threshold, the reactor is determined to be in a stable operating condition, and the temperatures of the inlet section S1, the middle section S2, and the outlet section S3 corresponding to the central and edge regions are obtained respectively. Step 4.2: Based on the deviations between the temperatures of the inlet section S1, the middle section S2, and the outlet section S3 and the corresponding set temperatures, adjust the heating power of the corresponding heating path sections respectively, and based on the deviations between the temperature of the cracked gas at the outlet of the reaction tube in the central area and the edge area and the corresponding set temperature at the outlet, adjust the set temperature corresponding to the outlet section S3. Step 4.3: Compare the temperature of each axial section in the central area and the edge area with the corresponding overheating set temperature. When the temperature of any axial section in the central area or the edge area exceeds the corresponding overheating set temperature, limit the power reduction of the regional heating path corresponding to the radial area to which the axial section belongs. Step 4.4: The execution priority of limiting power reduction is higher than the heating regulation priority of the section heating path, so that limiting power reduction is executed first when there is a conflict between radial overheat protection and axial segmented heating.

[0070] In one embodiment, when the absolute value of the change in ammonia flow rate at the reactor inlet is less than a stability threshold, the electronic control module determines that the reactor is in a stable operating condition and acquires the temperatures of the inlet section S1, the middle section S2, and the outlet section S3 corresponding to the central and edge zones, respectively. The electronic control module adjusts the heating power of the corresponding heating path based on the temperature deviation of each axial section. Specifically, the inlet section S1 uses a faster power response, the middle section S2 maintains the reaction temperature, and the outlet section S3 adjusts its set temperature according to the temperature of the cracked gas at the reactor outlet.

[0071] During segmented heating, the electronic control module simultaneously determines whether the central and edge zones have reached overheating conditions. When the temperature of any axial segment exceeds the corresponding overheating set temperature, the regional heating path of the radial area to which that segment belongs is subject to a power reduction limit, and the execution priority of the power reduction limit is higher than the normal heating adjustment of the axial segment. For example, when the inlet segment S1 needs to increase its heating power, but its central zone has already reached the overheating condition, the heating power of the central zone is reduced first, and normal adjustment is resumed after the overheating condition is resolved.

[0072] Through the above control process, the axial heating can be adapted to the endothermic state of different reaction stages, and local heat accumulation can be suppressed first when the axial heating demand conflicts with the radial overheat protection, thereby reducing the situation where the catalyst is at an excessively high temperature for a long time and the ineffective heating.

[0073] Furthermore, step 5 includes: Step 5.1: When the absolute value of the change in inlet ammonia flow rate is greater than the variable load threshold, determine that the reactor is in variable load condition, and judge whether the reactor is in loading or unloading state according to the direction of change in inlet ammonia flow rate. Step 5.2: When the inlet ammonia flow rate increases, increase the input power of the silicon carbide electric heating layer 19; when the inlet ammonia flow rate decreases, decrease the input power of the silicon carbide electric heating layer 19 to perform feedforward temperature regulation on the ammonia that has completed the first stage of preheating. Step 5.3: Compare the outlet ammonia temperature of the silicon carbide electric heating layer 19 with the preheating set temperature, and adjust the input power of the silicon carbide electric heating layer 19 according to the temperature difference between the two. At the same time, adjust the heating power of the regional heating path and the section heating path according to the temperature difference of different radial regions and different axial sections. Step 5.4: Obtain the reactor outlet temperature, and when the deviation between the reactor outlet temperature and the set outlet temperature is less than the outlet temperature stabilization threshold, end the variable load condition and control the reactor to enter the stable condition.

[0074] In one embodiment, when the absolute value of the change in inlet ammonia flow rate is greater than the load change threshold, the electronic control module determines that the reactor is in a load change condition and judges whether the reactor is in a loaded or unloaded state based on the direction of the flow rate change. When the inlet ammonia flow rate increases, the input power of the silicon carbide electric heating layer 19 is increased first to allow the secondary preheating zone to replenish the heat required for the increase in ammonia flow rate in advance; when the inlet ammonia flow rate decreases, the input power of the silicon carbide electric heating layer 19 is decreased first to reduce the heat accumulation caused by the decrease in the processed gas volume.

[0075] After the feedforward adjustment is completed, the electronic control module compares the outlet ammonia temperature of the silicon carbide electric heating layer 19 with the preheating set temperature, and corrects its input power according to the temperature deviation. At the same time, it adjusts the heating power of the regional heating path and the section heating path according to the temperature deviation of the central area, the edge area, the inlet section S1, the middle section S2 and the outlet section S3 respectively.

[0076] When the deviation between the reactor outlet temperature and the set outlet temperature is less than the outlet temperature stabilization threshold, the variable load condition ends and the system re-enters the stable condition. Through the above control process, the secondary preheating zone responds to significant changes in the reactor outlet temperature before the reaction zone makes segmented corrections, thereby reducing the heating lag caused by relying solely on outlet temperature feedback and lowering the possibility of insufficient temperature during loading or localized overheating during unloading.

[0077] exist Figure 9 and Figure 10 In the middle, Q in The ammonia flow rate at the reactor inlet is represented by ΔQ. in T represents the change in inlet ammonia flow rate. pre_out T represents the outlet ammonia temperature of the silicon carbide electric heating layer 19. wall and T wall_set T represents the actual wall temperature and the set wall temperature of the corresponding axial section of the reaction tube, respectively. out and T out_set ε1 and ε2 represent the reactor outlet temperature and the outlet temperature setpoint, respectively; ε2 represents the flow rate change threshold under variable load conditions; and ε4 represents the allowable deviation of the reactor outlet temperature. Figure 10 ε2 and Figure 8 The ε2 used for temperature judgment corresponds to different judgment processes. PID execution means adjusting the corresponding heating power according to the deviation between the actual temperature and the corresponding set temperature. When the deviation between the reactor outlet temperature and the outlet temperature set value is less than ε4, the stable operating condition is maintained or the variable load operating condition is ended and the stable operating condition is entered. If this condition is not met, the set temperature of the outlet section S3 and the corresponding heating power are corrected.

[0078] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An integrated ammonia cracking hydrogen production reactor based on energy staged utilization, characterized in that, include: Reactor body (22); The high-efficiency compact ammonia-hydrogen heat exchange unit (9) is integrated inside the reactor body (22) and forms a cold-side heat exchange channel for the ammonia gas to be cracked and a hot-side heat exchange channel for the cracked gas to be cracked, which is used to preheat the ammonia gas to be cracked by utilizing the residual heat carried by the cracked gas. A silicon carbide electric heating layer (19) is provided on the output side of the cold side heat exchange channel to receive ammonia gas that has completed the first stage of preheating and to allow the ammonia gas to pass through the silicon carbide electric heating layer (19) for the second stage of preheating. The reaction tube assembly is disposed on the output side of the silicon carbide electric heating layer (19). The reaction tube assembly includes multiple reaction tubes (17) for receiving ammonia gas that has completed secondary preheating and performing catalytic cracking. The cracked gas output side of the reaction tube assembly is connected to the heat exchange channel on the hot side. A space heating component is provided in correspondence with the reaction tube component, and forms a regional heating path that provides heating radially along the reaction tube component and a segment heating path that provides heating axially along the reaction tube (17), which is used to supplement the heat supply according to the reaction heat absorption requirements of different spatial positions of the reaction tube component. The high-efficiency compact ammonia-hydrogen heat exchange unit (9) includes alternating cold flow channel plates and hot flow channel plates. The cold flow channel plates form the cold side heat exchange channel, and the hot flow channel plates form the hot side heat exchange channel. The ammonia gas to be cracked and the cracked gas flow in opposite directions along the cold side heat exchange channel and the hot side heat exchange channel, respectively. The space heating component includes: A resistance wire (31) is provided, which is correspondingly arranged with each of the reaction tubes (17); The multiple reaction tubes (17) are divided into a central area and an edge area along the radial direction of the reaction tube assembly, and the resistance wires (31) corresponding to the central area and the edge area respectively form an independent heating zone path; Each of the reaction tubes (17) is divided into an inlet section S1, an intermediate section S2 and an outlet section S3 along the direction of ammonia flow. The resistance wires (31) corresponding to the inlet section S1, the intermediate section S2 and the outlet section S3 respectively form independent heating sections. The reactor body (22) is also equipped with: A silicon carbide outlet ammonia temperature sensor (20) is provided on the output side of the silicon carbide electric heating layer (19); A reaction tube inlet ammonia temperature sensor (21) is disposed between the silicon carbide electric heating layer (19) and the reaction tube assembly; Temperature sensor (23) at the inlet section of the central reaction tube, wherein the temperature sensor (23) at the inlet section of the central reaction tube is provided corresponding to the inlet section S1 of the central zone; The edge zone reaction tube inlet section temperature sensor (24) is provided corresponding to the inlet section S1 of the edge zone; A temperature sensor (25) is provided on the wall of the middle section of the central reaction tube, which is set in the middle section S2 of the central region. Temperature sensor (26) in the middle section of the edge region reaction tube, the temperature sensor (26) in the middle section of the edge region reaction tube is set in the middle section S2 of the edge region; Temperature sensor (27) at the outlet section of the central reaction tube, wherein the temperature sensor (27) at the outlet section of the central reaction tube is provided corresponding to the outlet section S3 of the central zone; Temperature sensor (28) at the outlet section of the reaction tube in the edge region, wherein the temperature sensor (28) at the outlet section of the reaction tube in the edge region is provided corresponding to the outlet section S3 of the edge region; A cracked gas temperature sensor (29) is installed at the outlet of the reaction tube (17) in the central region. A cracked gas temperature sensor (30) is provided at the outlet of the reaction tube (17) in the edge zone.

2. The integrated ammonia cracking hydrogen production reactor based on energy staged utilization according to claim 1, characterized in that, One end of the reactor body (22) is provided with: End cap (7), the end cap (7) covering the end of the reactor body (22); Fastening screw (1), the fastening screw (1) is connected between the end cap (7) and the reactor body (22) for fixing the end cap (7). Electrode base (8), the electrode base (8) is disposed on the end cap (7); Ammonia gas inlet pipe (4), which is connected to the cold side heat exchange channel, is used to introduce ammonia gas to be cracked into the high-efficiency compact ammonia-hydrogen heat exchange unit (9); The pyrolysis gas outlet pipe (5) is connected to the heat exchange channel on the hot side and is used to discharge the pyrolysis gas that has completed heat exchange.

3. The integrated ammonia cracking hydrogen production reactor based on energy staged utilization according to claim 2, characterized in that, The reactor body (22) also includes: A reactor inlet ammonia flow sensor (2) is installed at the ammonia inlet pipe (4); A reactor inlet ammonia temperature sensor (3) is installed at the ammonia inlet pipe (4); A heat exchanger heat inlet temperature sensor (10) is provided between the cracked gas output side of the reaction tube assembly and the heat exchange channel on the hot side. An ammonia temperature sensor (11) at the inlet of the electric heater is provided between the cold-side heat exchange channel and the silicon carbide electric heating layer (19). The reactor outlet temperature sensor (6) is located at the pyrolysis gas outlet pipe (5).

4. The integrated ammonia cracking hydrogen production reactor based on energy staged utilization according to claim 1, characterized in that, The reaction tube assembly includes: A support grid plate (16) is disposed inside the reactor body (22); Multiple reaction tubes (17) are arranged in an array on the support grid plate (16); A porous ceramic carrier (18) is disposed in the corresponding reaction tube (17); Catalyst coating (32), which is disposed on the porous ceramic support (18), is used to catalytically crack ammonia flowing through the reaction tube (17).

5. The integrated ammonia cracking hydrogen production reactor based on energy staged utilization according to claim 1, characterized in that, It also includes a composite insulation component disposed on the outside of the reaction tube assembly, the composite insulation component comprising: An air insulation layer (12) is disposed on the outside of the reaction tube assembly; Aerogel insulation layer (13), which covers the outside of the air insulation layer (12); A polyurethane foam insulation layer (14) is provided, which covers the outside of the aerogel insulation layer (13). A stainless steel outer layer (15) is wrapped around the outside of the polyurethane foam insulation layer (14) to provide external protection for the composite insulation component.

6. A control method for an integrated ammonia cracking hydrogen production reactor based on energy staged utilization, employing the integrated ammonia cracking hydrogen production reactor based on energy staged utilization as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Obtain the ammonia flow rate at the reactor inlet, the ammonia temperature at the outlet of the silicon carbide electric heating layer (19), the temperatures of different radial regions and different axial sections of the reaction tube assembly, and the reactor outlet temperature; Step 2: Based on the reactor's startup status and the change in the inlet ammonia flow rate, determine whether the reactor is currently in a cold start condition, a stable condition, or a variable load condition. Step 3: When the reactor is in cold start condition, control the silicon carbide electric heating layer (19) and space heating component to preheat, so that the heating position that first reaches the corresponding set temperature is switched to the heat preservation state, and ammonia gas is introduced after each heating position reaches the corresponding set temperature. Step 4: When the reactor is in a stable operating condition, adjust the heating power according to the radial region and axial section of the reaction tube assembly respectively, and when the overheating condition is met in any radial region, prioritize limiting the heating power corresponding to that radial region. Step 5: When the reactor is under variable load conditions, the feedforward power of the silicon carbide electric heating layer (19) is adjusted according to the direction of change of the inlet ammonia flow rate, and the heating power of the space heating component is adjusted according to the outlet ammonia temperature of the silicon carbide electric heating layer (19), the temperature of different radial regions and different axial sections. Step 6: Determine the operating condition control state based on the reactor outlet temperature and the temperatures of different radial regions and different axial sections, and control the reactor to enter the stable operating condition after the cold start condition or variable load condition meets the stability conditions.

7. The control method for an integrated ammonia cracking hydrogen production reactor based on energy staged utilization according to claim 6, characterized in that, Step 3 includes: Step 3.1: Control the silicon carbide electric heating layer (19) and the space heating component to heat up synchronously, and obtain the detection temperatures of the silicon carbide outlet ammonia temperature sensor (20), the central zone reaction tube outlet cracked gas temperature sensor (29), and the edge zone reaction tube outlet cracked gas temperature sensor (30), respectively. Step 3.2: Compare each detected temperature with the corresponding preheating set temperature, so that the heating position that reaches the corresponding preheating set temperature first is put into the heat preservation state, and the heating position that has not reached the corresponding preheating set temperature continues to rise until all heating positions reach the corresponding preheating set temperature. Step 3.3: Turn on the ammonia input and gradually increase the inlet ammonia flow rate so that the ammonia passes through the high-efficiency compact ammonia-hydrogen heat exchange unit (9), the silicon carbide electric heating layer (19) and the reaction tube assembly in sequence; Step 3.4: Adjust the heating power of the silicon carbide electric heating layer (19) and the space heating component according to the temperature of the cracked gas detected by the heat exchanger heat flow inlet temperature sensor (10), and end the cold start operation after the temperature of the cracked gas reaches the reaction set temperature and remains stable.

8. The control method for an integrated ammonia cracking hydrogen production reactor based on energy staged utilization according to claim 6, characterized in that, Step 4 includes: Step 4.1: When the absolute value of the change in the inlet ammonia flow rate is less than the stability threshold, the reactor is determined to be in a stable operating condition, and the temperatures of the inlet section S1, the middle section S2, and the outlet section S3 corresponding to the central and edge regions are obtained respectively. Step 4.2: Based on the deviations between the temperatures of the inlet section S1, the middle section S2, and the outlet section S3 and the corresponding set temperatures, adjust the heating power of the corresponding heating path sections respectively, and based on the deviations between the pyrolysis gas temperature at the outlet of the reaction tube in the central area and the edge area and the corresponding set outlet temperature, adjust the set temperature corresponding to the outlet section S3. Step 4.3: Compare the temperature of each axial segment in the central area and the edge area with the corresponding overheating set temperature. When the temperature of any axial segment in the central area or the edge area exceeds the corresponding overheating set temperature, limit the power reduction of the regional heating path corresponding to the radial area to which the axial segment belongs. Step 4.4: Control the execution priority of the power reduction limit to be higher than the heating regulation priority of the heating path segment, so as to prioritize the execution of the power reduction limit when there is a conflict between radial overheat protection and axial segmented heating.

9. The control method for an integrated ammonia cracking hydrogen production reactor based on energy staged utilization according to claim 6, characterized in that, Step 5 includes: Step 5.1: When the absolute value of the change in the inlet ammonia flow rate is greater than the variable load threshold, it is determined that the reactor is in a variable load condition, and the reactor is in a loading state or a unloading state according to the direction of the change in the inlet ammonia flow rate. Step 5.2: When the inlet ammonia flow rate increases, the input power of the silicon carbide electric heating layer (19) is increased; when the inlet ammonia flow rate decreases, the input power of the silicon carbide electric heating layer (19) is decreased, so as to perform feedforward temperature regulation on the ammonia that has completed the first stage of preheating. Step 5.3: Compare the outlet ammonia temperature of the silicon carbide electric heating layer (19) with the preheating set temperature, and adjust the input power of the silicon carbide electric heating layer (19) according to the temperature difference between the two. At the same time, adjust the heating power of the regional heating path and the segment heating path according to the temperature difference of different radial regions and different axial sections. Step 5.4: Obtain the reactor outlet temperature, and when the deviation between the reactor outlet temperature and the set outlet temperature is less than the outlet temperature stabilization threshold, end the variable load condition and control the reactor to enter the stable condition.

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