Modular ammonia synthesis reactor and method

Abstract

The application discloses a kind of modular ammonia synthesis reactor and method, it is related to chemical equipment technical field, including shell, the shell top is fixedly arranged with shell large lid, the shell inner wall top is fixedly connected with reactor small lid, the shell inner side is fixedly connected with reactor inner part;Its use method is: step 1, when normal production;Step 2, when coping with short-term power or raw material gas flow fluctuation;Step 3, when coping with night, rainy day long time low power scene;Step 4, when renewable energy power recovery.By reactor internal integrated heat exchanger and cold shock gas channel and multi-bed temperature accurate control, the efficient stable regulation and control of reaction temperature and wide load dynamic adjustment are realized, the technical effects of adapting renewable energy power supply rapid fluctuation, guaranteeing reaction system stable operation are reached, the deficiencies that it is poor in adaptability when coping with renewable energy power generation fluctuation, load regulation range is narrow are solved.

Description

Technical Field

[0001] This invention relates to the field of chemical equipment technology, specifically to a modular ammonia synthesis reactor and method. Background Technology

[0002] Since the Industrial Revolution, global carbon dioxide emissions have continued to rise, and climate change has become increasingly severe. The transition to low-carbon or zero-carbon industrial production has become a global consensus. Ammonia is one of the most important basic chemicals in agriculture, chemicals, and energy. The traditional Habor-Bosch ammonia synthesis process is a typical high-carbon dioxide emission process, accounting for 1% of global carbon dioxide emissions. In recent years, with the rapid development and maturation of renewable energy power generation technologies and water electrolysis hydrogen production technologies, green ammonia synthesis using green hydrogen as a raw material has gradually become an important solution for achieving deep emission reduction. In particular, it requires ammonia synthesis reactors with high load regulation capabilities and high integration, which can more effectively adapt to the fluctuations in renewable energy power and the distributed needs of green ammonia plants under completely off-grid conditions.

[0003] In the ammonia synthesis process, internal reactor temperature control is a core aspect. For multi-bed reactors, strict control of the inlet temperature of each catalyst bed is required to avoid local hot spots in the catalyst, which could lead to risks such as coking, deactivation, or runaway temperatures. With fluctuations in upstream feed gas supply due to renewable energy sources, achieving precise and rapid regulation of the internal temperature field of the reactor has become a key technical challenge, especially under ultra-low load conditions. If the reactor temperature can be maintained at its lower limit under low energy consumption conditions, allowing it to quickly resume high-load operation during the day when there is sufficient sunlight, the need for energy storage system configuration will be significantly reduced, thereby greatly reducing the levelized cost of green ammonia production.

[0004] Existing ammonia synthesis reactors are mostly designed for large-scale centralized production scenarios. In modular, off-grid green ammonia applications, they are not only difficult to adapt to changes in feed gas supply caused by fluctuations in renewable energy power generation, but also cannot achieve precise and rapid temperature field control to avoid catalyst risks. Furthermore, their complex internal structure and large size lead to high manufacturing and transportation costs and poor on-site deployment flexibility. At the same time, traditional miniaturized solutions have limited load adjustment range and need to rely on large-scale energy storage or grid-connected operation to maintain stability, making it difficult to meet the economic and adaptability requirements of green ammonia production in off-grid renewable energy scenarios. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a modular ammonia synthesis reactor and method, which solves the problem that traditional ammonia synthesis reactors in the prior art are mostly designed for large-scale centralized production and lack flexible temperature control mechanisms.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A modular ammonia synthesis reactor includes an outer shell, a large outer shell cover fixedly mounted on the top of the outer shell, a small reactor cover fixedly connected to the top of the inner wall of the outer shell, and reactor internals fixedly connected to the inner side of the outer shell. The reactor internals include an insulation layer and an insulation skin, both cylindrical and tightly attached to the inner side of the outer shell. A first catalytic bed is disposed at a slightly upper position inside the reactor internals, and a second catalytic bed is disposed at a slightly lower position inside the reactor internals. A first wire mesh is fixedly connected to the bottom of the first catalytic bed, and a second wire mesh is fixedly connected to the bottom of the second catalytic bed. An interlayer heat exchanger is fixedly connected to the bottom of the first wire mesh, and a first heat exchange tube and a first twisted iron are disposed inside the interlayer heat exchanger. A bottom heat exchanger is fixedly connected to the bottom of the second wire mesh, and a second heat exchange tube and a second twisted iron are disposed inside the bottom heat exchanger. A central tube is disposed through the axial center of the first and second catalytic beds.

[0007] A method of using a modular ammonia synthesis reactor, applied to the modular ammonia synthesis reactor according to any one of claims 1-9, the method comprising the following steps: Step 1: During normal production, the raw material gas is divided into three streams: zero-meter quench gas, interlayer heat exchanger cold gas, and bottom heat exchanger cold gas. These streams are introduced into the reactor through the zero-meter quench gas inlet, interlayer heat exchanger cold gas inlet, and bottom heat exchanger cold gas inlet on the outer shell, respectively. The zero-meter quench gas enters the quenching region uniformly through the openings in the zero-meter quench distribution pipe within the quenching region on the upper side of the first catalytic bed. The interlayer heat exchanger cold gas is preheated by flowing from bottom to top through the annular flow channel between the reactor internals and the outer shell before entering the interlayer heat exchanger through a gas conduit. The cold gas from the interlayer heat exchanger enters the shell side of the bottom heat exchanger. The three gas streams mix in the cooling zone and then enter the first catalytic bed for ammonia synthesis. The reactant gas from the outlet of the first catalytic bed enters the tube side of the interlayer heat exchanger for cooling. The cooled gas flows into the second catalytic bed to continue the ammonia synthesis reaction. The final reactant gas from the outlet of the second catalytic bed enters the tube side of the bottom heat exchanger for cooling. The cooled gas is collected through the gas collection box at the bottom of the bottom heat exchanger and finally flows out of the reactor from the hot gas outlet at the bottom of the shell. Step 2: When dealing with short-term fluctuations in power or feed gas flow, the temperature control system configured in the reactor obtains the inlet temperature signals of the first and second catalytic beds through thermocouples in the high-pressure thermocouple sheath. Based on the temperature signals, it automatically adjusts the opening degree and corresponding flow ratio of the control valves on the zero-meter quench gas inlet pipe, the interlayer heat exchanger's cold gas inlet pipe, and the bottom heat exchanger's cold gas inlet pipe to adjust the inlet temperature of the first and second catalytic beds. If adjusting the control valves still cannot meet the temperature requirements of the catalytic beds, the temperature control system activates the electric heater containing heating wires and connecting rods nested inside the central tube. It supplies power to the electric heater through electrodes to generate heat and supplement the heat, helping to establish thermal balance inside the reactor. Step 3: When dealing with long-term low power scenarios such as nighttime or rainy days, select either the heat preservation mode or the ultra-low load operation mode. When selecting the heat preservation mode, close the valves on the pipeline connecting the reactor to external equipment to form a closed internal flow zone in the reactor. The temperature control system switches to the heat preservation mode and controls the cycle start / stop and power adjustment of the electric heater based on the bed temperatures of the first and second catalytic beds fed back by thermocouples. When the bed temperature is lower than the lower limit of the suitable range, turn on the electric heater or increase the heating power. When the bed temperature is higher than the upper limit of the suitable range, reduce the power of the electric heater or turn off the electric heater to maintain the catalytic bed temperature within the suitable range. When selecting the ultra-low load operation mode, the temperature control system automatically adjusts the opening of the control valves on the zero-meter cold gas inlet pipeline, the control valves on the interlayer heat exchanger cold gas inlet pipeline, and the control valves on the bottom heat exchanger cold gas inlet pipeline to maintain the reactor operating at low rated capacity. When the temperature control system still cannot maintain the minimum temperature of the first and second catalytic beds after adjusting the control valves, the electric heater is intermittently turned on to supplement heat. Step 4: When renewable energy power is restored, if it is in heat preservation mode, open the valves on the pipeline connecting the reactor and external equipment to restore gas flow in the reactor. Switch the temperature control system to normal temperature control mode, and the electric heater continues to provide auxiliary heating until the temperature balance in the reactor is fully established, so that the reactor can quickly enter normal production. If it is in ultra-low load operation mode, gradually adjust the opening of the control valves on the zero-meter cold quench gas inlet pipeline, the control valves on the cold gas inlet pipeline of the interlayer heat exchanger, and the control valves on the cold gas inlet pipeline of the bottom heat exchanger through the temperature control system to increase the total flow rate of raw material gas and the ratio of each gas stream, so that the reactor can gradually return to high load operation.

[0008] This invention provides a modular ammonia synthesis reactor and method. It offers the following advantages: 1. This invention achieves efficient and stable regulation of reaction temperature and dynamic adjustment of wide load range by adopting an integrated heat exchanger and cold gas channel inside the reactor and precise temperature control of multiple beds. It achieves the technical effect of adapting to rapid fluctuations in renewable energy power supply and ensuring stable operation of the reaction system. Compared with the existing technology, traditional ammonia synthesis reactors are mostly designed for large-scale centralized production and lack flexible temperature control mechanisms. This invention solves the shortcomings of poor adaptability and narrow load adjustment range when dealing with fluctuations in renewable energy power generation.

[0009] 2. This invention adopts a technical solution of switching between a central tube-embedded electric heater and a cold / hot operating mode, which shortens the reactor start-up time and maintains the catalytic bed temperature under low power conditions. This achieves the technical effect of reducing the configuration requirements of the energy storage system and reducing the levelized cost of green ammonia production. Compared with the existing technology, which relies on large-scale energy storage or grid-connected operation to maintain stability and has a long cold start-up process, this invention solves the shortcomings of poor economic efficiency and inability to quickly restore high load operation in off-grid renewable energy scenarios.

[0010] 3. The present invention adopts a modular and compact structure and an integrated insulation layer and annular flow channel for reactor internals, which reduces the reactor's footprint, lowers manufacturing and transportation costs, and optimizes shell material requirements. This achieves the technical effect of improving the flexibility of on-site installation and deployment and saving overall material costs. Compared with the existing technology, the traditional ammonia synthesis reactor has a complex internal structure, large volume, and lacks targeted insulation design, which solves the shortcomings of high construction cost and poor adaptability to transportation and on-site deployment. Attached Figure Description

[0011] Figure 1 This is a schematic cross-sectional view of a modular ammonia synthesis reactor and method according to the present invention. Figure 2 This is a schematic diagram of the process flow of a modular ammonia synthesis reactor and method according to the present invention.

[0012] The components include: 1. Outer shell cover; 2. Outer shell; 3. Reactor cover; 4. Reactor internals; 5. Thermocouple high-pressure sleeve; 6. Thermocouple sleeve; 7. Packing seal; 8. First catalytic bed; 9. First wire mesh; 10. Interlayer heat exchanger; 11. First heat exchange tube; 12. First twisted iron; 13. Thermocouple conduit; 14. Second catalytic bed; 15. Bottom heat exchanger; 16. Second heat exchange tube; 17. Second twisted iron; 18. Gas collection box; 19. Gas pore; 20. Electrode; 21. Connecting rod; 22. Heating wire; 23. Zero-meter cold quench distribution tube; 24. Gas conduit; 25. Central tube; 26. Mica sheet; 27. Interlayer heat exchanger support platform; 28. Second wire mesh. Detailed Implementation

[0013] The technical solution of the present invention will now be clearly and completely described 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. Example

[0014] Please see the appendix Figure 1 This invention provides a modular ammonia synthesis reactor, comprising an outer shell 2, a large outer shell cover 1 fixedly disposed on the top of the outer shell 2, a small reactor cover 3 fixedly connected to the top of the inner wall of the outer shell 2, and a reactor inner component 4 fixedly connected to the inner side of the outer shell 2. The reactor inner component 4 includes a heat insulation layer and a heat insulation skin, which are cylindrical and tightly attached to the inner side of the outer shell 2. A first catalyst bed 8 is disposed at the upper part of the reactor inner component 4, and a second catalyst bed 14 is disposed at the lower part of the reactor inner component 4. A first wire mesh 9 is fixedly connected to the bottom of the first catalyst bed 8, and a second wire mesh 28 is fixedly connected to the bottom of the second catalyst bed 14. An interlayer heat exchanger 10 is fixedly connected to the bottom of the first wire mesh 9. A first heat exchange tube 11 and a first twisted iron 12 are disposed inside the interlayer heat exchanger 10. A bottom heat exchanger 15 is fixedly connected to the bottom of the second wire mesh 28. A second heat exchange tube 16 and a second twisted iron 17 are disposed inside the bottom heat exchanger 15. A central tube 25 is disposed through the axial center of the first catalyst bed 8 and the second catalyst bed 14.

[0015] The bottom heat exchanger 15 is fixedly connected to a gas collection box 18. The gas collection box 18 has evenly distributed air holes 19 on its side. The center tube 25 is nested inside an electric heater containing an electric heating wire 22 and a connecting rod 21. The electric heater is covered with a mica sheet 26. The outer cover 1 has an electrode port corresponding to the position of the electric heater. An electrode 20 is inserted into the electrode port and electrically connected to the electric heater.

[0016] A thermocouple conduit 13 is connected and fixedly connected to the top of the second catalytic bed 14. A thermocouple sleeve 6 is provided between the first catalytic bed 8 and the thermocouple conduit 13. A high-pressure thermocouple sleeve 5 is installed inside the thermocouple sleeve 6. The high-pressure thermocouple sleeve 5 passes through the interlayer heat exchanger 10, the first wire mesh 9, the first catalytic bed 8, the reactor small cover 3 and the outer shell large cover 1 in sequence from the thermocouple conduit 13, and its top end extends to the top of the outer shell large cover 1. A packing seal 7 is provided at the connection between the thermocouple sleeve 6 and the reactor small cover 3.

[0017] A zero-meter quench distribution pipe 23 is fixedly connected to the quench area on the upper side of the first catalytic bed 8. The pipe wall of the zero-meter quench distribution pipe 23 has evenly distributed openings. A zero-meter quench gas inlet is provided on the side wall of the outer shell 2 at the position corresponding to the zero-meter quench distribution pipe 23. The zero-meter quench gas inlet is connected to the zero-meter quench distribution pipe 23 through a pipeline. A control valve is provided on the zero-meter quench gas inlet pipeline.

[0018] The bottom of the outer shell 2 is provided with a cold air inlet port for the interlayer heat exchanger 10. The cold air inlet port of the interlayer heat exchanger 10 is connected to the lower shell side of the interlayer heat exchanger 10 through a gas conduit 24. The gas conduit 24 is arranged in a circular periodic pattern along the radial section of the reactor central axis. An extension pipe is connected to the upper shell side of the interlayer heat exchanger 10. The top of the extension pipe extends to the quenching region and is connected to the quenching region. A control valve is provided on the cold air inlet pipe of the interlayer heat exchanger 10.

[0019] The bottom of the outer shell 2 is also provided with a cold air inlet pipe for the bottom heat exchanger 15. The cold air inlet pipe for the bottom heat exchanger 15 is connected to the lower shell side of the bottom heat exchanger 15 through a pipe. The upper shell side of the bottom heat exchanger 15 is sealed to the bottom of the central tube 25. The top of the central tube 25 extends to the cold quenching area and is connected to the cold quenching area. A control valve is provided on the cold air inlet pipe of the bottom heat exchanger 15.

[0020] The interlayer heat exchanger 10 has a shell-and-tube structure. The interlayer heat exchanger 10 is equipped with annular baffles or double-arch baffles. The first twisted iron 12 is embedded in the first heat exchange tube 11. The bottom of the interlayer heat exchanger 10 is equipped with an interlayer heat exchanger support platform 27, which is fixedly connected to the reactor internals 4. The tube side inlet of the interlayer heat exchanger 10 is connected to the outlet of the first catalytic bed 8, and the tube side outlet is connected to the inlet of the second catalytic bed 14.

[0021] The bottom heat exchanger 15 has a shell-and-tube structure and is equipped with annular baffles or double-arch baffles inside. The second twisted iron 17 is embedded inside the second heat exchange tube 16. The tube side inlet of the bottom heat exchanger 15 is connected to the outlet of the second catalytic bed 14, and the tube side outlet is connected to the gas collection box 18. The bottom of the gas collection box 18 is connected to the hot gas outlet port at the bottom of the outer shell 2.

[0022] The insulation layer of the reactor internals 4 consists of an insulating aluminum sheet, rock wool, and an annular flow channel from the outside to the inside. Aerogel, insulating adhesive, or other insulation materials or forms can also be used. The annular flow channel is located between the reactor internals 4 and the outer shell 2. The cold air introduced into the cold air inlet of the interlayer heat exchanger 10 can flow from bottom to top along the annular flow channel to achieve preheating of the cold air and insulation of the outer shell 2.

[0023] Please see the appendix Figure 2A method of using a modular ammonia synthesis reactor, applied to any of the modular ammonia synthesis reactors of claims 1-9, characterized in that the method includes the following steps: Step 1: During normal production, the raw material gas is divided into three streams: zero-meter quench gas, cold gas from the interlayer heat exchanger 10, and cold gas from the bottom heat exchanger 15. These streams are introduced into the reactor through the zero-meter quench gas inlet, the interlayer heat exchanger 10 inlet, and the bottom heat exchanger 15 inlet on the outer shell 2, respectively. The zero-meter quench gas enters the quenching region uniformly through the openings in the wall of the zero-meter quench distribution pipe 23 in the quenching region on the upper side of the first catalytic bed 8. The cold gas from the interlayer heat exchanger 10 is preheated by flowing from bottom to top through the annular flow channel between the reactor internals 4 and the outer shell 2, and then enters the interlayer heat exchanger through the gas conduit 24. The cold gas from the bottom heat exchanger 15 enters the shell side of the reactor 10. After the three gas streams are mixed in the cooling zone, they enter the first catalytic bed 8 to carry out the ammonia synthesis reaction. The reaction gas from the outlet of the first catalytic bed 8 enters the tube side of the interlayer heat exchanger 10 to cool down. The cooled gas flows into the second catalytic bed 14 to continue the ammonia synthesis reaction. The final reaction gas from the outlet of the second catalytic bed 14 enters the tube side of the bottom heat exchanger 15 to cool down. The cooled gas is collected through the gas holes 19 opened on the side of the gas collection box 18 at the bottom of the bottom heat exchanger 15, and finally flows out of the reactor from the hot gas outlet pipe at the bottom of the outer shell 2. Step 2: When dealing with short-term fluctuations in power or feed gas flow, the temperature control system configured in the reactor obtains the inlet temperature signals of the first catalytic bed 8 and the second catalytic bed 14 through the thermocouples in the high-pressure thermocouple sheath 5. Based on the temperature signals, it automatically adjusts the opening degree of the control valves on the zero-meter cold quench gas inlet pipe, the control valves on the cold gas inlet pipe of the interlayer heat exchanger 10, and the control valves on the cold gas inlet pipe of the bottom heat exchanger 15, as well as the corresponding gas flow ratio, to adjust the inlet temperature of the first catalytic bed 8 and the second catalytic bed 14. If the temperature requirements of the catalytic bed cannot be met after adjusting the control valves, the temperature control system starts the electric heater containing the electric heating wire 22 and the connecting rod 21 nested inside the central tube 25. The electric heater is powered by the electrode 20 to generate heat to supplement the heat and help establish thermal balance inside the reactor. Step 3: When dealing with long-term low power scenarios such as nighttime or rainy days, select either the heat preservation mode or the ultra-low load operation mode. When selecting the heat preservation mode, close the valves on the pipeline connecting the reactor to external equipment to form a closed internal flow zone in the reactor. The temperature control system switches to the heat preservation mode and controls the cycle start / stop and power adjustment of the electric heater based on the bed temperature of the first catalytic bed 8 and the second catalytic bed 14 fed back by the thermocouple. When the bed temperature is lower than the lower limit of the suitable range, turn on the electric heater or increase the heating power. When the bed temperature is higher than the upper limit of the suitable range, reduce the power of the electric heater or turn off the electric heater to maintain the catalytic bed temperature within the suitable range. When selecting the ultra-low load operation mode, the temperature control system automatically adjusts the opening of the control valves on the zero-meter cold gas inlet pipeline, the control valves on the cold gas inlet pipeline of the interlayer heat exchanger 10, and the control valves on the cold gas inlet pipeline of the bottom heat exchanger 15 to maintain the reactor operating at a low rated capacity. When the temperature control system still cannot maintain the minimum temperature of the first catalytic bed 8 and the second catalytic bed 14 after adjusting the control valves, the electric heater is intermittently turned on to supplement heat. Step 4: When renewable energy power is restored, if it is in heat preservation mode, open the valve on the pipeline connecting the reactor and external equipment to restore the flow of gas in the reactor. The temperature control system switches to normal temperature control mode, and the electric heater continues to provide auxiliary heating until the temperature balance in the reactor is fully established, so that the reactor can quickly enter the normal production state. If it is in ultra-low load operation mode, gradually adjust the opening of the control valve on the zero-meter cold quench gas inlet pipeline, the control valve on the cold gas inlet pipeline of the interlayer heat exchanger 10, and the control valve on the cold gas inlet pipeline of the bottom heat exchanger 15 through the temperature control system to increase the total flow rate of raw material gas and the ratio of each gas stream, so that the reactor can gradually resume high load operation.

[0024] The following is a description with reference to specific embodiments: Example

[0025] The reactor inlet gas has a total flow rate of 350 kmol / h, a temperature of 140℃, and a pressure of 100 bar, suitable for a rated ammonia synthesis capacity of 5000 TPA. The reactor inlet gas is first divided into three streams by a gas splitter: zero-meter quench gas, interlayer heat exchanger 10 inlet quench gas, and bottom heat exchanger 15 inlet quench gas, with flow rates of 0~52.5 kmol / h, 140~157.5 kmol / h, and 157.5~192.5 kmol / h, respectively. The zero-meter quench gas enters the zero-meter quench distribution pipe 23 in the upper quench mixing zone of the reactor through the zero-meter quench gas inlet pipe at the top of the reactor, and is then evenly distributed to the quench zone through the openings arranged in the zero-meter quench distribution pipe 23. A zero-meter quench gas control valve is installed on the zero-meter quench gas inlet pipeline to control the flow rate and adjust the inlet gas temperature of the first catalytic bed 8. After the cold gas from the bottom of the reactor enters the reactor, it flows from bottom to top through the annular channel, between the reactor internals 4 and the outer shell 2, and then through the gas conduit 24 into the lower shell side of the interlayer heat exchanger 10. After countercurrent heat exchange with the outlet gas of the first catalytic bed 8 in the tube side, the temperature rises to 360~380℃, and flows through the sleeve gap into the quench region to mix with the zero-meter quench gas.

[0026] Two symmetrical gas ducts 24 are provided, symmetrically arranged in the radial section with the reactor central axis as the reference, to ensure uniform gas distribution. The annular flow channel is used for the annular gap between the outer shell 2 and the reactor internals 4, ensuring that the temperature of the outer shell 2 of the reactor is below 180℃, reducing heat radiation loss, and also preheating the inlet cold gas of the interlayer heat exchanger 10, reducing the material selection requirements of the outer shell 2. The insulation layer is a composite of insulation aluminum skin and insulation rock wool. The inlet cold gas control valve of the interlayer heat exchanger 10 is installed on the inlet pipe to control the flow rate and adjust the temperature of the inlet gas of the second catalytic bed 14.

[0027] The catalyst loading volume of the first catalyst bed 8 is 0.55 m³. 3 The catalyst loading volume of the second catalyst bed 14 is 1m³. 3 The interlayer heat exchanger 10 is a shell-and-tube heat exchanger with a three-layer double-arched internal baffle. It houses approximately 1000 heat exchange tubes 11 with an inner diameter of 12mm. Twisted iron 12 is inserted into the heat exchange tubes 11 to enhance gas turbulence and improve heat transfer. The total effective heat exchange area is approximately 25m². 2 The cold gas inlet of the bottom heat exchanger 15 enters the reactor through the bottom heat exchanger cold gas inlet pipe on the bottom side of the reactor. It passes through the shell side from bottom to top and exchanges heat with the gas outlet of the second catalytic bed 14 in the tube side, raising the temperature to 360~380℃. Then it flows along the central pipe 25 connected to the shell side to the quench zone and mixes with the zero-meter quench gas and the gas outlet of the extension pipe of the interlayer heat exchanger 10.

[0028] A bottom heat exchanger inlet cold air control valve is installed on the inlet cold air pipe of the bottom heat exchanger 15 for flow regulation. The bottom heat exchanger 15 is a shell-and-tube heat exchanger with a five-layer double-arched internal baffle plate and approximately 1700 heat exchange tubes 16 with an inner diameter of 12mm. Twisted iron 17 is inserted into the wall of the heat exchange tubes 16 to enhance gas turbulence and improve heat transfer. The total effective heat exchange area is 32.3m². 2 The three gases mentioned above mix in the cooling zone. The temperature of the mixed gas is 360°C and the pressure is 99.5 bar. It then enters the first catalytic bed 8 to carry out the ammonia synthesis reaction.

[0029] The gas exiting the first catalytic bed 8 has a temperature of 490-500°C, a pressure of 99.0 bar, and an ammonia concentration of approximately 10%. This gas enters the tube-side inlet of the interlayer heat exchanger 10 for heat exchange and cooling, and then flows out from the tube-side outlet at a temperature of 380°C. It then enters the second catalytic bed 14 for a two-stage ammonia synthesis reaction. The gas temperature after the reaction is 440°C, the pressure is 98.5 bar, and the ammonia concentration is 14.5%. It then enters the tube-side inlet of the bottom heat exchanger 15 for heat exchange and cooling, reducing the temperature to 320°C and the pressure to 98.4 bar. Afterward, it flows out of the reactor from the hot gas outlet at the bottom of the reactor and enters the subsequent equipment of the ammonia synthesis unit for water cooling and ammonia separation. The parameters of this embodiment correspond to a rated ammonia synthesis capacity of 5000 TPA at full load, with a single-pass conversion rate of 22% and a total pressure drop of 1.6 bar.

[0030] Thermocouples and temperature sensors are installed at the inlet of the first catalytic bed 8 and the inlet of the second catalytic bed 14. The signals are fed back to the zero-meter cold gas control valve and the cold gas control valve of the interlayer heat exchanger 10. When the upstream hydrogen and nitrogen flow rates change with the fluctuation of renewable energy, the reaction system maintains the inlet temperature of the first catalytic bed 8 and the second catalytic bed 14 at 360℃ and 380℃ respectively through the temperature control system to maintain the stability of the reaction. Example

[0031] Example 1 describes the reactor operation under 100% load conditions. If the ammonia synthesis unit is driven by off-grid renewable energy, when the renewable energy generation is in a valley or there is no power generation at all, power is provided only through energy storage devices or independent generators. In the off-grid photovoltaic night state, the front-end electrolyzer, nitrogen generation unit and green ammonia unit are suitable for coordinated ultra-low load operation to avoid the need for large and expensive energy storage devices.

[0032] When the reactor in Example 1 is operating at a low load of 20% of its rated capacity, the total inlet gas flow rate is 70 kmol / h, the pressure is 68 bar, and the temperature is 160°C. The inlet gas is split by a gas splitter into zero-meter quench gas, interlayer heat exchanger 10 inlet cold gas, and bottom heat exchanger 15 inlet cold gas flow rates, which change from 0~52.5 kmol / h, 140~157.5 kmol / h, and 157.5~192.5 kmol / h under rated load to 0~10.5 kmol / h, 28~31.5 kmol / h, and 31.5~38.5 kmol / h under 20% low load, respectively.

[0033] This adjustment is achieved by adjusting the opening of control valves installed on the three gas pipelines. It requires no manual intervention and is automatically completed by the temperature control method. At this time, the inlet temperature of the first catalytic bed 8 is 370℃, the inlet temperature of the second catalytic bed 14 is 390℃, the corresponding outlet temperature of the first catalytic bed 8 is 473℃, the ammonia concentration is 9%, the outlet temperature of the second catalytic bed 14 is 320℃, the ammonia concentration is 13.5%, the single-pass conversion rate of the reactor is 19.5%, and the total pressure drop is 0.8 bar.

[0034] When a special situation occurs in the reaction system, the electric heater is automatically turned on to heat the gas in the central tube 25 to the required temperature. When the temperatures of the first catalytic bed 8 and the second catalytic bed 14 meet the requirements, the circuit can be automatically adjusted according to the actual situation. This process can be manually adjusted or automatically implemented by embedding a temperature control system. Example

[0035] Example 2 describes the reactor operating at low load when there is a lack of power. For green ammonia plants based on off-grid photovoltaics, if the energy storage scale is to be further reduced, green ammonia production can be stopped at night or during rainy weather, while maintaining the temperature of the first catalyst bed 8 and the second catalyst bed 14 in the reactor at 20°C. When renewable power is restored, it can be directly and quickly started up to the rated capacity from the hot state, avoiding the slow cold start process.

[0036] When the reactor in Example 1 is not producing and is only kept warm, under natural conditions, even if the heat insulation layer hinders heat dissipation, the temperature of the first catalytic bed 8 and the second catalytic bed 14 will still drop to about 200~250°C within 16 hours. During continuous rainy weather, the temperature will drop further to below 100°C or even room temperature.

[0037] In a 16-hour nighttime scenario, the valves on the pipelines connecting the reactor to other equipment are closed to form a closed internal flow zone in the reactor. Then, the temperature control system is switched to the heat preservation mode. Temperature sensors installed at the inlets of the first catalytic bed 8 and the second catalytic bed 14 feed back the bed temperature to the temperature control system, which controls the cycle start and stop and power adjustment of the electric heater: when the bed temperature is below 320°C, the heating power is turned on or increased, and vice versa, the power is reduced or turned off.

[0038] As renewable power gradually recovers, the valves connecting the reactor to other equipment are opened to restore gas circulation. At the same time, the temperature control system switches to temperature control mode, and the electric heater continues to provide auxiliary heating until the temperature balance inside the reactor is established, enabling the ammonia synthesis unit to start up quickly and reach full load.

[0039] 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. A modular ammonia synthesis reactor, comprising a shell (2), characterized in that: The outer shell (2) is fixedly provided with a large outer shell cover (1) at the top, and a small reactor cover (3) is fixedly connected to the top of the inner wall of the outer shell (2). The inner side of the outer shell (2) is fixedly connected with a reactor inner part (4). The reactor inner part (4) includes a heat insulation layer and a heat insulation skin and is cylindrical and tightly attached to the inner side of the outer shell (2). A first catalyst bed (8) is provided at the upper part of the reactor inner part (4), and a second catalyst bed (14) is provided at the lower part of the reactor inner part (4). A first wire mesh (9) is fixedly connected to the bottom of the first catalyst bed (8). The bottom of the second catalytic bed (14) is fixedly connected to a second wire mesh (28), the bottom of the first wire mesh (9) is fixedly connected to an interlayer heat exchanger (10), the interlayer heat exchanger (10) is provided with a first heat exchange tube (11) and a first twisted iron (12), the bottom of the second wire mesh (28) is fixedly connected to a bottom heat exchanger (15), the bottom heat exchanger (15) is provided with a second heat exchange tube (16) and a second twisted iron (17), and a central tube (25) is provided through the axial center of the first catalytic bed (8) and the second catalytic bed (14). The bottom heat exchanger (15) is fixedly connected to a gas collection box (18). The gas collection box (18) has evenly distributed air holes (19) on its side. The center tube (25) is nested inside an electric heater containing an electric heating wire (22) and a connecting rod (21). The electric heater is fitted with a mica sheet (26) on its outside. The outer cover (1) has an electrode opening corresponding to the position of the electric heater. An electrode (20) is inserted into the electrode opening and electrically connected to the electric heater. The bottom of the outer shell (2) is also provided with a cold air inlet pipe for a bottom heat exchanger (15). The cold air inlet pipe of the bottom heat exchanger (15) is connected to the lower side of the shell side of the bottom heat exchanger (15) through a pipe. The upper side of the shell side of the bottom heat exchanger (15) is sealed to the bottom of the central tube (25). The top of the central tube (25) extends to the cold quenching area and is connected to the cold quenching area. A control valve is provided on the cold air inlet pipe of the bottom heat exchanger (15).

2. The modular ammonia synthesis reactor according to claim 1, characterized in that: The second catalyst bed (14) is connected to a thermocouple conduit (13) through and fixedly connected to the top. A thermocouple sleeve (6) is provided between the first catalyst bed (8) and the thermocouple conduit (13). A high-pressure thermocouple sleeve (5) is provided inside the thermocouple sleeve (6). The high-pressure thermocouple sleeve (5) passes through the interlayer heat exchanger (10), the first wire mesh (9), the first catalyst bed (8), the reactor small cover (3) and the outer shell large cover (1) in sequence from the thermocouple conduit (13), and the top end extends to the top of the outer shell large cover (1). A packing seal (7) is provided at the connection between the thermocouple sleeve (6) and the reactor small cover (3).

3. The modular ammonia synthesis reactor according to claim 1, characterized in that: A zero-meter quench distribution pipe (23) is fixedly connected in the quench area on the upper side of the first catalyst bed (8). The wall of the zero-meter quench distribution pipe (23) is provided with evenly distributed openings. The side wall of the outer shell (2) is provided with a zero-meter quench gas inlet corresponding to the position of the zero-meter quench distribution pipe (23). The zero-meter quench gas inlet is connected to the zero-meter quench distribution pipe (23) through a pipeline. A control valve is provided on the zero-meter quench gas inlet pipeline.

4. A modular ammonia synthesis reactor according to claim 1, characterized in that: The bottom of the outer shell (2) is provided with a cold air inlet port for the interlayer heat exchanger (10). The cold air inlet port of the interlayer heat exchanger (10) is connected to the lower shell side of the interlayer heat exchanger (10) through a gas conduit (24). The gas conduit (24) is arranged in a circular periodic pattern along the radial section of the reactor central axis. An extension pipe is connected to the upper shell side of the interlayer heat exchanger (10). The top of the extension pipe extends to the quenching region and is connected to the quenching region. A control valve is provided on the cold air inlet pipe of the interlayer heat exchanger (10).

5. A modular ammonia synthesis reactor according to claim 1, characterized in that: The interlayer heat exchanger (10) is a shell-and-tube structure. The interlayer heat exchanger (10) is provided with annular baffles or double-bow baffles. The first twisted iron (12) is embedded in the first heat exchange tube (11). The bottom of the interlayer heat exchanger (10) is provided with an interlayer heat exchanger support platform (27) and is fixedly connected to the reactor internals (4). The tube side inlet of the interlayer heat exchanger (10) is connected to the outlet of the first catalytic bed (8), and the tube side outlet is connected to the inlet of the second catalytic bed (14).

6. A modular ammonia synthesis reactor according to claim 1, characterized in that: The bottom heat exchanger (15) is a shell-and-tube structure, with annular baffles or double-bow baffles inside. The second twisted iron (17) is embedded inside the second heat exchange tube (16). The tube side inlet of the bottom heat exchanger (15) is connected to the outlet of the second catalytic bed (14), and the tube side outlet is connected to the gas collection box (18). The bottom of the gas collection box (18) is connected to the hot gas outlet port at the bottom of the outer shell (2).

7. A modular ammonia synthesis reactor according to claim 1, characterized in that: The insulation layer of the reactor internals (4) consists of an insulating aluminum sheet, rock wool and an annular flow channel from the outside to the inside. It can also be made of aerogel, insulating adhesive or other insulating materials. The annular flow channel is located between the reactor internals (4) and the outer shell (2). The cold air introduced into the cold air inlet of the interlayer heat exchanger (10) can flow from bottom to top along the annular flow channel to achieve preheating of the cold air and insulation of the outer shell (2).

8. A method of using a modular ammonia synthesis reactor, applied to the modular ammonia synthesis reactor according to any one of claims 1-7, characterized in that: The method includes the following steps: Step 1: During normal production, the raw material gas is divided into three streams: zero-meter quench gas, cold gas from the interlayer heat exchanger (10), and cold gas from the bottom heat exchanger (15). These streams are introduced into the reactor through the zero-meter quench gas inlet, the interlayer heat exchanger (10), and the bottom heat exchanger (15) inlet on the outer shell (2), respectively. The zero-meter quench gas enters the quenching region uniformly through the opening in the wall of the zero-meter quench distribution pipe (23) in the quenching region on the upper side of the first catalytic bed (8). The cold gas from the interlayer heat exchanger (10) flows from bottom to top through the annular flow channel between the reactor internals (4) and the outer shell (2) for preheating, and then enters the interlayer heat exchanger through the gas conduit (24). The shell side of the bottom heat exchanger (15) is filled with cold gas. The three gas streams are mixed in the cooling zone and then enter the first catalytic bed (8) to carry out the ammonia synthesis reaction. The reaction gas at the outlet of the first catalytic bed (8) enters the tube side of the interlayer heat exchanger (10) to cool down. The cooled gas flows into the second catalytic bed (14) to continue the ammonia synthesis reaction. The final reaction gas at the outlet of the second catalytic bed (14) enters the tube side of the bottom heat exchanger (15) to cool down. The cooled gas is collected through the gas holes (19) opened on the side of the gas collection box (18) at the bottom of the bottom heat exchanger (15) and finally flows out of the reactor from the hot gas outlet pipe at the bottom of the shell (2). Step 2: When dealing with short-term power or raw gas flow fluctuations, the temperature control system configured in the reactor obtains the inlet temperature signals of the first catalytic bed (8) and the second catalytic bed (14) through the thermocouple in the high-pressure thermocouple sleeve (5). Based on the temperature signals, the control valves on the zero-meter cold gas inlet pipe, the interlayer heat exchanger (10), and the bottom heat exchanger (15) automatically adjust the opening degree and the corresponding flow ratio of the control valves on the cold gas inlet pipe and the corresponding gas flow ratio to adjust the inlet temperature of the first catalytic bed (8) and the second catalytic bed (14). If the temperature requirements of the catalytic bed cannot be met after adjusting each control valve, the temperature control system starts the electric heater containing the electric heating wire (22) and the connecting rod (21) nested inside the central tube (25). The electric heater is powered by the electrode (20) to generate heat to supplement the heat and help the reactor establish a thermal balance. Step 3: When dealing with long-term low power scenarios such as nighttime or rainy days, select the heat preservation mode or ultra-low load operation mode. When selecting the heat preservation mode, close the valves on the pipeline connecting the reactor and external equipment to form a closed internal flow zone in the reactor. Switch the temperature control system to the heat preservation mode. Based on the bed temperatures of the first catalytic bed (8) and the second catalytic bed (14) fed back by the thermocouple, control the cycle start / stop and power adjustment of the electric heater. When the bed temperature is lower than the lower limit of the suitable range, turn on the electric heater or increase the heating power. When the bed temperature is higher than the upper limit of the suitable range, reduce the power. When the electric heater power is low or the electric heater is turned off, the temperature of the catalytic bed is maintained in a suitable range. When the ultra-low load operation mode is selected, the control valves on the zero-meter cold gas inlet pipe, the control valves on the cold gas inlet pipe of the interlayer heat exchanger (10), and the control valves on the cold gas inlet pipe of the bottom heat exchanger (15) are automatically adjusted by the temperature control system to maintain the reactor at a low rated capacity. When the temperature control system still cannot maintain the lowest temperature of the first catalytic bed (8) and the second catalytic bed (14) after adjusting each control valve, the electric heater is intermittently turned on to supplement the heat. Step 4: When renewable energy power is restored, if it is in heat preservation mode, open the valve on the pipeline connecting the reactor and external equipment to restore the flow of gas in the reactor. The temperature control system switches to normal temperature control mode, and the electric heater continues to provide auxiliary heat until the temperature balance in the reactor is fully established, so that the reactor can quickly enter the normal production state. If it is in ultra-low load operation mode, gradually adjust the opening of the control valve on the zero-meter cold gas inlet pipeline, the control valve on the cold gas inlet pipeline of the interlayer heat exchanger (10), and the control valve on the cold gas inlet pipeline of the bottom heat exchanger (15) through the temperature control system to increase the total flow rate of raw material gas and the proportion of each gas stream, so that the reactor can gradually resume high load operation.

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