Liquid metal ammonia decomposition reactor with partitioned sound field regulation and control function and using method of liquid metal ammonia decomposition reactor

Abstract

The invention relates to the technical field of hydrogen production through ammonia decomposition, and particularly provides a liquid metal ammonia decomposition reactor with partitioned sound field regulation and control and a use method of the liquid metal ammonia decomposition reactor. The reactor comprises a reaction container, liquid metal arranged in the reaction container, an air inlet formed in the bottom area of the reaction container and communicated with the liquid metal, and an air outlet formed in the upper portion of the reaction container and communicated with the outside. A first sound field unit is arranged on the outer side of a reaction container bottom plate, and a second sound field unit is arranged on the upper area of the outer wall of the reaction container in the height direction of liquid metal. The first sound field unit is a high-frequency sound vibration unit, and the second sound field unit is a low-frequency sound vibration unit. The bottom high-frequency sound field enables the ammonia gas bubbles to generate interface reconstruction and splitting in the generation stage, and the upper low-frequency sound field enables the ammonia gas bubbles to obtain disturbance and path extension in the floating stage, so that the interface refreshing efficiency of a liquid metal system is improved, and a gas-liquid interface is kept at a consistent activation level in the whole reaction process; the overall reaction rate of the ammonia decomposition reaction is improved.

Description

Technical Field

[0001] This application relates to the field of ammonia decomposition for hydrogen production technology, and more specifically, to a liquid metal ammonia decomposition reactor with zoned acoustic field control and its usage method. Background Technology

[0002] Ammonia decomposition for hydrogen production has become an important research direction in hydrogen energy utilization systems due to its advantages such as safe storage and transportation, zero carbon emissions, and direct coupling with hydrogen energy systems. Traditional solid metal catalysts such as Ru and Ni can achieve high activity under high temperature conditions, but their reaction rates are limited in the medium and low temperature ranges, and they suffer from problems such as sintering deactivation, insufficient thermal stability, and limited interfacial mass transfer efficiency, making it difficult to meet the current demand for efficient and low-energy-consumption ammonia decomposition technology.

[0003] With the increasing application of liquid metals in energy catalysis, their high thermal conductivity, interfacial reconfigurability, and resistance to sintering have made liquid metal-catalyzed ammonia decomposition a new research direction. Studies have shown that the ammonia decomposition reaction mainly occurs at the interface of liquid metals. Ammonia molecules undergo adsorption, gradual breakage of N–H bonds, and the generation of intermediates such as NH2, NH, and N at this interface, followed by desorption to generate hydrogen and nitrogen. By dispersing ammonia gas into bubbles and introducing them into the liquid metal, a larger contact interface can be formed within the liquid metal, allowing the gas to continuously react with the metal interface during its ascent, thereby improving the ammonia decomposition activity to some extent. However, in existing systems, the formation, size, and movement of bubbles mainly rely on natural processes. Larger bubbles have insufficient specific surface area, resulting in limited disturbance to the liquid metal interface during ascent and difficulty in maintaining continuous interface renewal. The rising speed and path of bubbles in liquid metal are difficult to control, leading to insufficient residence time and incomplete reaction. Simultaneously, the natural reconfiguration intensity of the liquid metal interface is limited, lacking active control methods, thus restricting the utilization efficiency of the gas-liquid interface. Therefore, the liquid metal system still faces bottlenecks in improving the overall reaction rate.

[0004] Therefore, an improved technology is needed that can actively regulate bubble morphology and movement behavior and enhance interface refresh efficiency in order to further improve the ammonia decomposition capacity in liquid metal systems. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by providing a liquid metal ammonia decomposition reactor with zoned acoustic field control and its usage method, thereby solving the problems of difficult bubble control and insufficient interface refresh that limit ammonia decomposition efficiency in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This application provides a liquid metal ammonia decomposition reactor with zoned acoustic field control, including a reaction vessel, liquid metal disposed within the reaction vessel, an air inlet disposed at the bottom region of the reaction vessel and communicating with the liquid metal, and an air outlet disposed at the top of the reaction vessel and communicating with the outside; a first acoustic field unit is disposed on the outer side of the bottom plate of the reaction vessel, and a second acoustic field unit is disposed on the upper region of the outer wall of the reaction vessel along the height direction of the liquid metal; the first acoustic field unit is a high-frequency acoustic vibration unit, and the second acoustic field unit is a low-frequency acoustic vibration unit.

[0007] This application constructs a sound field control system arranged in sections along the height of the liquid metal within a reaction vessel. This system subjects the formation and buoyancy of bubbles in the liquid metal to different sound fields, thereby maintaining interfacial disturbance throughout the entire upward path. A first sound field unit, located on the outer side of the reaction vessel's bottom plate, generates high-frequency acoustic vibrations. These vibrations create rapid, alternating interfacial compression and expansion in the bottom region of the liquid metal, introducing a strong sound pressure gradient on the bubble surface. This causes ammonia gas entering the liquid metal through the inlet to undergo periodic interfacial deformation during the initial bubble formation stage, inducing surface reconstruction and even rupture of the bubbles. This results in smaller, more uniformly distributed floating bubbles, increasing the specific surface area and interfacial activation level. A second sound field unit, located on the upper part of the outer wall of the reaction vessel, generates low-frequency acoustic vibrations. These vibrations create a large-scale acoustic flow and periodic pressure field in the upper region of the liquid metal. This causes bubbles rising to this region to experience velocity fluctuations, path deviations, or localized aggregation changes under the influence of acoustic radiation forces, thus maintaining interfacial disturbance as the bubbles approach the liquid surface. By applying high-frequency and low-frequency sound fields at different heights, a multi-scale sound field process is formed inside the liquid metal from bottom to top, causing the bubble to continuously experience dynamic interface vibration and path regulation throughout the entire floating process, thus maintaining a stable level of interface activation.

[0008] Furthermore, the first acoustic field unit is attached to the outer wall of the bottom of the reaction vessel, and an acoustic coupling layer is provided between the first acoustic field unit and the reaction vessel. The acoustic coupling layer reduces the interface gap, improves the energy transfer efficiency of high-frequency acoustic vibrations to the bottom of the reaction vessel, and makes the acoustic field distribution in the bottom region more uniform, which is beneficial for the primary ammonia bubbles to obtain stable high-frequency disturbances in the early stage.

[0009] Furthermore, the second sound field unit is configured with at least one low-frequency acoustic vibration module along the circumferential direction of the outer wall of the reaction vessel. By configuring multiple low-frequency acoustic vibration modules distributed circumferentially along the outer wall, the sound field coverage of the upper region of the liquid metal becomes more uniform, ensuring that bubbles rising in different directions are all subjected to low-frequency disturbances, thus reducing the inhomogeneity of the upper bubble paths.

[0010] Furthermore, the vibration direction of the low-frequency acoustic vibration module is tilted downward relative to the normal direction of the outer wall of the reaction vessel. The downward tilt of the vibration direction of the low-frequency acoustic vibration module creates a disturbance component pointing downward toward the interior of the liquid metal in the direction of the rising bubbles' movement. This makes the rising rhythm of the bubbles slower and the path longer as they approach the liquid, thereby increasing the chances of them experiencing acoustic field disturbances in the upper region.

[0011] Furthermore, the bottom surface of the reaction vessel is provided with multiple upward-protruding structures. These upward-protruding structures on the bottom surface can break the flat, straight surface of the bottom region, causing the initial bubbles to deform or slightly shift after generation, thus allowing them to be more fully affected by high-frequency acoustic vibrations in the bottom region.

[0012] Furthermore, a mesh baffle is installed on the inner wall of the reaction vessel near the lower part of the second sound field unit, extending along the inner wall of the reaction vessel towards the center. The mesh baffle can change the local flow field when the bubbles rise, causing the bubbles to change velocity or slightly disperse when passing through the baffle, forming a certain buffer transition area and providing a more stable target for the upper sound field.

[0013] Furthermore, the mesh baffle is connected to the inner wall of the reaction vessel via a flexible support, which allows the mesh baffle to undergo slight displacement when the second acoustic field unit vibrates. The flexible support enables the mesh baffle to oscillate slightly under low-frequency acoustic vibration. The oscillating baffle structure creates disturbances, causing the bubbles passing through it to continuously undergo new local interface changes, which helps to further enhance the interface refresh effect in the upper region.

[0014] This application also proposes a method for using a liquid metal ammonia decomposition reactor with zoned acoustic field control, the method comprising the following steps: S1. Add liquid metal into the reaction vessel and heat to the predetermined operating temperature; S2. Ammonia gas is introduced into the liquid metal through the air inlet, causing the ammonia gas to form floating bubbles inside the liquid metal. S3. Drive the first sound field unit to generate a high-frequency sound field in the liquid metal and act on the floating bubbles; S4. Drive the second sound field unit to generate a low-frequency sound field in the upper region of the liquid metal, which acts on the bubbles in that region. S5. Discharge the gas obtained from the decomposition from the outlet.

[0015] Furthermore, the center operating frequency of the first sound field unit is greater than 20kHz, while the center operating frequency of the second sound field unit is less than 5kHz. Sound vibrations above 20kHz fall into the ultrasonic frequency band, which can produce significant cavitation and interfacial contraction effects, making it more effective in refreshing the gas-liquid interface and breaking up initial large bubbles. Sound vibrations below 5kHz are suitable for forming overall fluid oscillations, making the movement of bubbles in the upper region easier to modulate.

[0016] Furthermore, the first sound field unit is driven in a pulsed manner, while the second sound field unit is driven continuously. The high-frequency sound field is driven in a pulsed manner, releasing acoustic energy in a concentrated manner within a short period of time, enhancing the bubble breaking intensity, and reducing the energy consumption caused by continuous ultrasound. The low-frequency sound field is driven continuously, creating a stable low-frequency disturbance field in the upper region, thereby maintaining a continuous influence on the bubble's movement path.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention constructs a partitioned sound field control system inside the liquid metal, consisting of a high-frequency sound field at the bottom and a low-frequency sound field at the top, so that the bubbles undergo interface reconstruction and splitting during the generation stage and are disturbed and have their paths extended during the floating stage. This improves the interface refresh efficiency of the liquid metal system, increases the specific surface area of ​​the bubbles, keeps the gas-liquid interface at a high level of activation throughout the reaction, and improves the overall reaction rate of the ammonia decomposition reaction.

[0018] (2) The method of using the present invention drives high-frequency and low-frequency sound fields in sequence during the reaction process, so that the entire process of bubble generation, floating and discharge is under the continuous sound field regulation, thereby ensuring that the partitioned sound field effect of the device can be stably and uniformly reproduced, so that the bubble interface state maintains a consistent activation level during the reaction process, which is beneficial to improving mass transfer efficiency and promoting the full progress of ammonia decomposition reaction. Attached Figure Description

[0019] Figure 1 A schematic diagram of a liquid metal ammonia decomposition reactor with zoned acoustic field control provided by the present invention; Figure 2 A top view of the bottom of a liquid metal ammonia decomposition reactor with zoned acoustic field control provided by the present invention; Figure 3 A schematic diagram of another liquid metal ammonia decomposition reactor with zoned acoustic field control provided by the present invention; Figure 4 This is a schematic flowchart illustrating the usage method of a liquid metal ammonia decomposition reactor with zoned acoustic field control provided by the present invention.

[0020] Icons: 1-Reaction vessel; 2-Liquid metal; 3-Air inlet; 4-Air outlet; 5-First sound field unit; 6-Second sound field unit; 7-Protrusion; 8-Mesh baffle. Detailed Implementation

[0021] To make the implementation process of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings.

[0022] Example 1: This invention provides a liquid metal ammonia decomposition reactor with zoned acoustic field control, such as... Figure 1 As shown, it includes a reaction container 1, liquid metal 2 disposed inside the reaction container 1, an air inlet 3 disposed at the bottom region of the reaction container 1 and communicating with the liquid metal 2, and an air outlet 4 disposed at the top of the reaction container 1 and communicating with the outside; a first sound field unit 5 is disposed on the outer side of the bottom plate of the reaction container 1, and a second sound field unit 6 is disposed on the upper region of the outer wall of the reaction container 1 along the height direction of the liquid metal 2; the first sound field unit 5 is a high-frequency sound vibration unit, and the second sound field unit 6 is a low-frequency sound vibration unit.

[0023] The reaction vessel 1 is a vertical, sealed structure. Its sidewalls, bottom, and top cover are all integrally machined or welded from high-temperature and corrosion-resistant stainless steel or nickel-based alloy materials, ensuring excellent sealing and structural stability in the ammonia and liquid metal 2 environment. The reaction vessel 1 is cylindrical with a diameter of 20-30 cm to achieve a uniform internal flow field and predictable bubble rise paths. Liquid metal 2 is filled inside the reaction vessel 1, with its height below 85-95% of the height of the reaction vessel 1. The liquid metal 2 is selected from gallium, gallium-indium alloy, or gallium-tin alloy, and is heated to a molten state by an external heating device, forming a stable and continuous liquid column within the reaction vessel 1. Using liquid metal 2 as a catalyst to decompose ammonia can lower the reaction temperature of the ammonia decomposition reaction. Inlet 3 is the outlet of an inlet pipe extending downwards from the center of the top of reaction vessel 1. This inlet pipe enters the interior of reaction vessel 1 from the center of the top cover plate, with its end located at the bottom of reaction vessel 1 and directly connected to liquid metal 2, allowing ammonia gas to be introduced into liquid metal 2 in the form of fine bubbles. The end of the inlet pipe has a porous structure to improve ammonia gas dispersion. Outlet 4 is located at the upper part of reaction vessel 1 near the side wall. Outlet 4 is situated in the high region above the liquid metal 2 and is connected to an external exhaust pipe or analysis device via a sealed connection, used to discharge the mixed gas generated after the decomposition of ammonia gas in liquid metal 2. Because outlet 4 is located at the upper part near the side wall, it ensures that the gas rising to the gas phase zone is smoothly discharged and does not stagnate at the top of reaction vessel 1.

[0024] In this embodiment, a first acoustic field unit 5 is provided on the outer side of the bottom plate of the reaction vessel 1. The first acoustic field unit 5 is a high-frequency acoustic field unit used to apply high-frequency vibration to the bottom region of the liquid metal 2. The first acoustic field unit 5 is preferably a piezoelectric high-frequency acoustic transducer, which is attached to the reaction vessel 1 and arranged in surface contact with the bottom plate of the reaction vessel 1. It is reliably positioned by a fixing plate, metal clamp, or bolt assembly to ensure that the vibration energy is stably transmitted to the bottom of the vessel. Preferably, a load-bearing support structure is provided at the bottom of the reaction vessel 1, so that the area where the first acoustic field unit 5 is located is in a suspended state to avoid the first acoustic field unit 5 being compressed and to ensure stable operation of acoustic coupling. When the first acoustic field unit 5 is working, it generates dense and rapid interfacial micro-vibrations on the bottom plate of the reaction vessel 1. This vibration acts on the interior of the liquid metal 2, causing the bottom gas-liquid interface to be continuously renewed in a short time, forming a significant interface refresh effect. Building upon this, the primary bubbles generated by the air inlet 3 in the liquid metal 2 are subjected to high-frequency vibrations immediately upon formation. Their surfaces undergo periodic contraction and fluctuation, leading to a more stable, small-scale structure and a smaller, more uniform bubble size. This reduction in bubble size further increases their specific surface area, providing a larger contact interface for the gas in the liquid metal 2. This, in turn, provides higher interfacial reactivity and more sufficient mass transfer conditions for the subsequent flotation stage.

[0025] To ensure that the vibrations generated by the first acoustic field unit 5 can be efficiently transmitted to the bottom plate of the reaction vessel 1 and further act on the liquid metal 2, an acoustic coupling layer is provided between the first acoustic field unit 5 and the outer wall of the bottom plate of the reaction vessel 1. The acoustic coupling layer fills any small gaps that may exist between the transducer and the metal bottom plate, eliminates air gaps at the solid contact interface, enhances the transducer's vibration driving capability at the bottom of the reaction vessel 1, and allows acoustic energy to act on the bottom liquid metal 2 region with higher efficiency. This reduces the interface acoustic impedance, improves the acoustic coupling efficiency, and ensures that the primary bubbles obtain stable and sufficient interface disturbance in the early stages of formation. The acoustic coupling layer is preferably made of high-temperature resistant acoustic conductive silicone, solid acoustic conductive pads, or acoustic conductive grease containing metal oxide fillers, etc., whose acoustic impedance matches the metal substrate, reducing acoustic energy reflection at the interface and increasing transmittance. The thickness of the acoustic coupling layer is preferably controlled within the range of 0.1-1 mm to avoid attenuation effects caused by excessive layer thickness while filling the interface. The acoustic coupling layer is kept evenly spread during installation by a clamping structure and maintains a good fit during transducer operation.

[0026] Furthermore, the second sound field unit 6 is a low-frequency sound field unit, located in the upper region of the outer wall of the reaction vessel 1. It establishes a wide-range low-frequency oscillation field in the upper region of the liquid metal 2, improving the gas-liquid interface refresh rate and providing a more sufficient reaction interface and higher mass transfer efficiency for the ammonia decomposition reaction. The second sound field unit 6 includes at least one low-frequency acoustic vibration module. When only one low-frequency acoustic vibration module is used, it is preferably arranged in the upper-middle region of the side wall of the reaction vessel 1 so that its vibration surface can cover the main rising path of the bubbles in the upper part of the liquid metal 2, thereby effectively disturbing the rising bubbles. When multiple low-frequency acoustic vibration modules are used, each module is arranged at equal intervals along the circumference of the outer wall of the reaction vessel 1, so that vibration energy is transmitted into the interior of the liquid metal 2 from multiple directions. Multiple modules can be installed at the same height to form a ring vibration band, or they can be arranged in layers according to the liquid level of the liquid metal 2, so that each height region can obtain the effect of low-frequency vibration, enhancing the overall disturbance amplitude and coverage of the upper region. A ceramic reflective baffle is attached to the inner surface of the side wall of the reaction vessel 1 without a low-frequency acoustic vibration module. This baffle is used to reflect the low-frequency sound waves generated by the second sound field unit 6, so as to form a superimposed sound field or standing wave enhancement zone inside the liquid metal 2, thereby enhancing the control effect on the bubbles.

[0027] The low-frequency acoustic vibration module is fixed to the outer wall of the reaction vessel 1 via a bracket, clamp, or screw connection. The vibration surface of the module is in close contact with the side wall of the vessel to achieve good acoustic vibration coupling. To improve the interference direction of the low-frequency vibration on the fluid inside the liquid metal 2, the vibration direction of each low-frequency acoustic vibration module is inclined downward (i.e., towards the bottom) relative to the normal direction of the outer wall of the reaction vessel 1. The wedge gap formed by the inclined installation is compensated by filling the space between the vibration surface and the outer wall of the reaction vessel 1 with a flexible acoustic coupling pad or a wedge-shaped compensation component matching the inclination angle, so that the vibration surface still maintains a large area of ​​contact even when tilted. This inclination forms a vibration vector from the outside to the inside of the liquid metal 2 along the height direction of the reaction vessel 1, giving the disturbance component a downward tilting tendency towards the bottom. The tilt angle is determined based on the module installation space and the disturbance effect, preferably 10°-45°, so that the vibration energy can form an inward and downward periodic disturbance in the upper region of the liquid metal 2, causing the bubbles about to float to the liquid surface to experience velocity fluctuations, local displacement or slight delay in this region, thereby extending their residence path and keeping the bubbles in an interface disturbance state before contacting the liquid.

[0028] A large number of carbon fiber or alumina ceramic fiber filaments with diameters of 0.05-0.3 mm and lengths of 5-30 mm are dispersed in liquid metal, causing them to float. During their ascent, bubbles readily adhere briefly to the surface of the fiber filaments. Under the combined influence of a high-frequency sound field at the bottom and a low-frequency sound field at the top, the fiber filaments vibrate at multiple scales, causing the bubbles to change from a near-spherical shape to a flattened or irregular shape, increasing the contact area at the gas-liquid interface. Simultaneously, the minute frictional heat generated by the fiber vibration and the heat from material loss create a localized temperature rise near the gas-liquid interface, which, in conjunction with the bubble deformation effect, enhances the interface activation capacity, thereby further improving the ammonia decomposition efficiency.

[0029] To enhance the fluid disturbance effect at the bottom region of the liquid metal 2, and to cause deformation and interfacial instability of the primary bubbles at the moment of formation, multiple upward-facing small protrusions 7 are provided on the inner surface of the bottom of the reaction vessel 1, such as... Figure 2 As shown. The protrusion 7 is preferably cylindrical, pyramidal, or conical in shape, with a height of 3-15 mm, a bottom diameter or bottom edge length of 2-6 mm, and a center-to-center distance of 5-25 mm between adjacent protrusions 7, forming several micro-protrusions 7 of similar size and uniform distribution in the bottom region. The protrusions 7 are arranged in an array or ring in the bottom region of the reactor, giving the bottom space near the inlet 3 a moderate geometric change, thereby causing the primary bubbles formed by ammonia in the liquid metal 2 to undergo slight deformation or displacement when they detach from the bottom surface, which is beneficial to the early formation of interface disturbance. The protrusions 7 are preferably formed by machining the same stainless steel or nickel-based alloy as the material of the reaction vessel 1 directly on the inner surface of the vessel bottom plate, such as by local turning, milling, spot welding, or additive manufacturing processes; or prefabricated high-temperature resistant metal protrusions can be used and fixed to the inner surface of the bottom plate by welding or mechanical fastening. The top of protrusion 7 has a rounded transition or a pointed shape. The pointed structure can introduce a local interface contraction effect during the attachment or detachment of bubbles, increasing the initial interface instability at the moment of bubble formation. The rounded top, on the other hand, is conducive to forming a smooth separation point, reducing the risk of bubbles accumulating on the bottom surface. Under the combined action of multiple protrusions 7, the streamline structure of the bottom liquid metal 2 region changes from the original flat flow surface to a multi-point detachment interface with local disturbances. This allows the bubbles generated from the air inlet 3 to undergo shape changes, contact surface fluctuations, and slight directional shifts in the early stages of formation, providing a more favorable initial state for interface reconstruction and size reduction under the high-frequency vibration of the first sound field unit 5.

[0030] In practical applications, ammonia gas enters the bottom of reaction vessel 1 through the top-mounted inlet pipe. Upon contact with liquid metal 2, it forms primary bubbles near the bottom protrusions 7. Due to the presence of multiple uniformly sized micro-protrusions 7 at the bottom, the bubbles exhibit slight deformation and interface disturbance upon detachment from the bottom surface, providing initial conditions for subsequent interface activation. The first acoustic field unit 5, located on the outer side of the bottom plate of reaction vessel 1, applies high-frequency vibrations to the interior of liquid metal 2, continuously refreshing the bottom gas-liquid interface. In the early stages of bubble rise, interface contraction, fluctuations, and size reduction occur, resulting in a larger specific surface area. As the bubbles rise, they enter the area of ​​action of the second acoustic field unit 6. The low-frequency acoustic vibration module, inclinedly arranged on the sidewall of reaction vessel 1, introduces slow-amplitude vibrations into the upper region of liquid metal 2, causing the bubbles to deviate from their path or experience local velocity changes before approaching the liquid, while maintaining interface disturbance. After multi-stage interface activation, the generated gas finally reaches the liquid surface and enters the upper gas phase region, subsequently exiting through the outlet 4 located at the top of reaction vessel 1. The overall structural arrangement ensures that the bubbles are at a high level of interfacial activation during formation, rising, and discharging, thereby improving the gas-liquid contact efficiency required for the ammonia decomposition reaction and enhancing the overall reaction rate.

[0031] Example 2: Based on Example 1, this example further optimizes the structure of the upper region of reaction vessel 1, such as... Figure 3 As shown, this is to improve the interface state of the bubbles before they enter the working area of ​​the second sound field unit 6.

[0032] In this embodiment, the second sound field unit 6 consists of two low-frequency acoustic vibration modules at different heights arranged on both sides of the reaction vessel 1 to cover more of the liquid metal 2 area; and the low-frequency acoustic vibration modules are tilted downwards at 15° to facilitate extending the bubble path. In this embodiment, a mesh baffle 8 is also provided on the inner wall of the reaction vessel 1 below the second sound field unit 6. The mesh baffle 8 extends along the inner wall of the reaction vessel 1 towards the center, and its coverage extends to the rest of the cross-section of the reaction vessel 1 except for the area occupied by the air inlet 3 pipe, so that the entire rising channel forms a mesh disturbance interface. The mesh baffle 8 is specifically a stainless steel wire mesh, a perforated metal plate, or a high-temperature resistant metal mesh, which generates moderate local disturbance to the rising flow field without obstructing the bubble rising channel. The thickness of the mesh baffle 8 is 0.2-1mm, and the aperture range is preferably 2-4mm. This causes the bubble to deform, fluctuate in speed, or disperse locally when it passes through this area. This further introduces local interface changes on the basis of the bottom high-frequency sound field control, forming a stable transition disturbance zone before the bubble enters the upper low-frequency sound field area.

[0033] To enable the mesh baffle 8 to adapt to the low-frequency vibrations applied by the second sound field unit 6, in this embodiment, the mesh baffle 8 is connected to the inner wall of the reaction vessel 1 via a flexible support. The flexible support is preferably made of metal spring sheet, high-temperature resistant silicone rubber strip, or heat-resistant composite sheet, and its flexible structure allows the mesh baffle 8 to oscillate slightly under the influence of the low-frequency sound field. The flexible support is fixed to the inner wall of the reaction vessel 1 by welding, screwing, or clamping, allowing for elastic displacement of 0.5-2 mm while maintaining structural stability. The periodic oscillation of the mesh baffle 8 under low-frequency vibrations creates a local disturbance zone around it, causing the rising bubbles to continuously experience new interface changes as they pass through this area, enhancing the degree of interface activation and improving the consistency of bubble control by low-frequency vibrations in the upper region.

[0034] The above structure allows the bubbles to obtain richer and more uniform interface morphology changes before entering the effective range of the second sound field unit 6, providing a more responsive interface state for the low-frequency vibration of the second sound field unit 6 and improving the interface refresh effect of the upper liquid metal 2 region.

[0035] Example 3: Based on the apparatus of Example 1, this application also proposes a method for using a liquid metal ammonia decomposition reactor with zoned acoustic field control, such as... Figure 4 As shown, the method includes the following steps: S1. Add liquid metal 2 to reaction vessel 1 and heat to the predetermined operating temperature; before the operation begins, add liquid metal 2 to reaction vessel 1 so that the liquid level reaches the height required by the device design. Subsequently, heat reaction vessel 1 through a heating device to make liquid metal 2 reach a stable molten state, so as to form a liquid column environment that runs through the entire height, thereby providing a uniform reaction medium for the decomposition reaction after ammonia enters the interior of liquid metal 2.

[0036] S2. Ammonia gas is introduced into the liquid metal 2 through the air inlet 3, causing the ammonia gas to form floating bubbles inside the liquid metal 2; ammonia gas is also introduced into the bottom region of the liquid metal 2 through the air inlet 3 pipe extending into the reaction vessel 1, causing the ammonia gas to be released in the form of bubbles in the liquid metal 2. The ammonia gas rises from the bottom to the liquid surface, maintaining continuous contact with the interface of the liquid metal 2 during its floating path, thereby supporting the catalytic decomposition process.

[0037] S3. Drive the first sound field unit 5 to generate a high-frequency sound field in the liquid metal 2, which acts on the floating bubbles; activate the first sound field unit 5 arranged on the outside of the bottom plate of the reaction vessel 1, so that its output high-frequency sound vibration is transmitted to the interior of the liquid metal 2. The high-frequency sound field causes the interface of the newly formed bubble to produce rapid micro-scale vibration or deformation, so that the bubble obtains significant interface disturbance in the early stage of floating, thereby increasing the activation degree of the bubble surface and the contact area with the liquid metal 2.

[0038] S4. Drive the second sound field unit 6 to generate a low-frequency sound field in the upper region of the liquid metal 2, which acts on the bubbles in that region. When the bubbles rise to the upper region of the liquid metal 2, activate the second sound field unit 6, which is arranged on the upper part of the outer wall of the reaction vessel 1, to output low-frequency vibrations. The low-frequency sound field can form a slow, periodic flow field change in the upper layer of the liquid metal 2, causing the bubbles to deviate from their paths, undergo local deformation, or experience velocity disturbances, thereby prolonging the residence time of the bubbles in the decomposition region and further enhancing the kinetic activation ability of the bubble interface.

[0039] S5. The decomposed gas is discharged from the outlet 4. After the ammonia gas undergoes a decomposition reaction at the gas-liquid interface, nitrogen and hydrogen are generated, which rise to the upper space above the liquid surface and are finally discharged from the outlet 4 on the upper part of the reaction vessel 1 near the side wall, thus realizing the continuous discharge of the reaction gas.

[0040] In this embodiment, the center operating frequency of the first sound field unit 5 is set to be greater than 20 kHz, while the center operating frequency of the second sound field unit 6 is set to be less than 5 kHz. Sound vibrations above 20 kHz belong to the ultrasonic frequency band and can excite interfacial contraction, local cavitation, or high-speed deformation in the bottom region of the liquid metal 2, causing newly formed large bubbles to break up or activate the interface in the early stages of rising, thereby increasing the specific surface area of ​​the bubbles and enhancing their reactive contact with the liquid metal 2. Sound vibrations below 5 kHz are more suitable for forming overall fluid oscillations in the upper part of the reaction vessel 1, making the bubble's movement path, velocity changes, and interface morphology in this region more easily and continuously modulated, which is beneficial for maintaining the stabilizing effect of the upper region's sound field on the bubbles.

[0041] Furthermore, the first sound field unit 5 is driven in a pulse mode, while the second sound field unit 6 is driven in a continuous mode. When the first sound field unit 5 operates in pulse mode, its acoustic vibration output starts and stops according to a preset pulse period, so that high-frequency acoustic energy is concentrated and input to the bottom region of the liquid metal 2 during the pulse-on phase. The concentrated release of energy can generate strong interface disturbance and local breakage of the nascent bubbles in a very short time, thereby expanding the specific surface area of ​​the bubbles and increasing the activation degree of the gas-liquid interface; at the same time, during the pulse-off phase, the acoustic load is significantly reduced, which helps to reduce the continuous heat accumulation of the transducer and reduce the overall energy consumption. Preferably, the pulse period is 10ms-500ms, the duty cycle is set to 20%-80%, and it is dynamically adjusted according to the bubble generation rate, the flow state of the liquid metal 2, and the reaction load to obtain a more suitable high-frequency acoustic field effect state. The second sound field unit 6 is driven in a continuous mode, maintaining stable low-frequency vibration in the upper region of the liquid metal 2, so that the gas is continuously modulated by the low-frequency acoustic field in the later stage of the rise. Continuous low-frequency vibrations can create a stable and slowly changing disturbance field in the upper region, causing the path, velocity, or interface morphology of the rising bubbles to continuously change as they pass through this region. This helps to prolong the contact time between the bubbles and the liquid metal 2 interface and enhances the interface activation effect in this region. The continuous driving method has high stability under low-frequency sound fields, ensuring that the upper liquid metal 2 region maintains continuous control over the bubble motion state, further improving the overall decomposition efficiency.

[0042] In summary, this embodiment employs different driving methods for the high-frequency and low-frequency sound fields, ensuring that the entire process of bubble generation, rising, and discharging in liquid metal 2 is under continuous and targeted sound field control, thereby achieving higher interface refresh efficiency and a more complete ammonia decomposition reaction effect.

[0043] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A zoned sound field regulated liquid metal ammonia decomposition reactor, comprising a reaction vessel, a liquid metal arranged in the reaction vessel, a gas inlet arranged in a bottom region of the reaction vessel and in communication with the liquid metal, and a gas outlet arranged in an upper region of the reaction vessel and in communication with the outside, characterized in that: A first acoustic field unit is provided on the outer side of the bottom plate of the reaction vessel, and a second acoustic field unit is provided on the upper region of the outer wall of the reaction vessel along the height direction of the liquid metal; the first acoustic field unit is a high-frequency acoustic vibration unit, and the second acoustic field unit is a low-frequency acoustic vibration unit.

2. The zoned sound field regulated liquid metal ammonia decomposition reactor of claim 1, wherein: The first sound field unit is attached to the outer wall of the bottom of the reaction vessel, and an acoustic coupling layer is provided between the first sound field unit and the reaction vessel.

3. The zoned sound field regulated liquid metal ammonia decomposition reactor of claim 1, wherein: The second sound field unit is configured with at least one low-frequency acoustic vibration module along the circumferential direction of the outer wall of the reaction vessel.

4. The zoned sound field regulated liquid metal ammonia decomposition reactor of claim 3, wherein: The vibration direction of the low-frequency acoustic vibration module is inclined downward relative to the normal direction of the outer wall of the reaction vessel.

5. The zoned sound field regulated liquid metal ammonia decomposition reactor of claim 1, wherein: The bottom surface of the reaction vessel is provided with multiple upward-protruding structures.

6. The zoned sound field regulated liquid metal ammonia decomposition reactor of claim 1, wherein: A mesh baffle is provided on the inner wall of the reaction vessel near the lower part of the second sound field unit, and the mesh baffle extends along the inner wall of the reaction vessel towards the center.

7. The liquid metal ammonia decomposition reactor with zoned acoustic field control according to claim 6, characterized in that: The mesh baffle is connected to the inner wall of the reaction vessel via a flexible support member, which allows the mesh baffle to undergo slight displacement when the second sound field unit vibrates.

8. A method of using a liquid metal ammonia decomposition reactor with zoned acoustic field control, implemented by using the reactor according to any one of claims 1-7, characterized in that: Includes the following steps: S1. Add liquid metal into the reaction vessel and heat to the predetermined operating temperature; S2. Ammonia gas is introduced into the liquid metal through the air inlet, causing the ammonia gas to form floating bubbles inside the liquid metal; S3. Drive the first sound field unit to generate a high-frequency sound field in the liquid metal and act on the floating bubble; S4. Drive the second sound field unit to generate a low-frequency sound field in the upper region of the liquid metal, which acts on the bubbles in that region. S5. Discharge the gas obtained from the decomposition from the outlet.

9. The method of using the liquid metal ammonia decomposition reactor with zoned acoustic field control according to claim 8, characterized in that: The center operating frequency of the first sound field unit is greater than 20kHz, and the center operating frequency of the second sound field unit is less than 5kHz.

10. The method of using the liquid metal ammonia decomposition reactor with zoned acoustic field control according to claim 9, characterized in that: The first sound field unit is driven in a pulse mode, and the second sound field unit is driven in a continuous mode.

Images