Apparatus and method for hydrogen production by microwave resonance plasma torch cracking of ammonia

Abstract

The present disclosure provides a device for producing hydrogen by cracking ammonia using a microwave resonance plasma torch, which comprises a microwave unit adapted to generate microwaves, and a reaction unit connected to the microwave unit. The reaction unit comprises a resonance torch. The resonance torch comprises a housing having a closed end and an open end, a resonance cavity being formed between the closed end and the open end, an air inlet being provided on an outer wall of the housing and being in communication with the resonance cavity, and a central electrode being arranged in the resonance cavity. Microwaves are fed into the resonance cavity from the closed end to generate microwave resonance, and a plasma region is formed around a tip of the central electrode close to the open end, so that ammonia flowing from the air inlet is cracked when passing through the plasma region to generate a cracked gas containing hydrogen. The present disclosure also provides a method for producing hydrogen by cracking ammonia using a microwave resonance plasma torch.

Description

Technical Field

[0001] This disclosure relates to the field of zero-carbon fuels and fuel reforming, and in particular to a method and apparatus for producing hydrogen from ammonia by microwave resonant plasma torch pyrolysis. Background Technology

[0002] Ammonia (NH3) is an excellent hydrogen carrier, possessing advantages such as high hydrogen carrying density and safe storage and transportation. However, the NH bond in the ammonia molecule has a high binding energy, and the ammonia cracking reaction requires significant energy consumption, resulting in high energy consumption in typical ammonia cracking hydrogen production systems. In recent years, developing efficient and energy-saving ammonia cracking hydrogen production technologies has become an international research hotspot. Currently, ammonia cracking hydrogen production methods can be divided into two main categories: thermal and non-thermal. Thermal decomposition is the most widely used traditional method, typically requiring a high-temperature heat source (above 700℃) combined with a catalyst to achieve a cracking rate of over 90%. However, due to heat loss from the high-temperature heat source, the system's thermal efficiency is often low. Besides its reliance on catalysts and large size, the heating system also suffers from thermal inertia, resulting in a long hydrogen production response time and poor dynamic responsiveness, making it difficult to adapt to the transient operating conditions of mobile power sources such as internal combustion engines and their demands on hydrogen supply. If engine exhaust waste heat is used to crack ammonia, the cracker's operating temperature and the internal combustion engine's operating power are highly coupled. Under cold start and low-load conditions, the engine's exhaust temperature is too low, significantly reducing the cracker's hydrogen production efficiency. In non-thermal decomposition, common methods include electrolysis and photocatalysis. These methods typically require catalysts, and the cracking rate and feed gas flow rate are usually low, making them far from practical application. In summary, whether it is thermal or non-thermal ammonia decomposition for hydrogen production, there are often problems such as long system hydrogen production response time and large volume, making it difficult to apply to mobile power sources such as internal combustion engines. Summary of the Invention

[0003] In view of this, the present disclosure provides an apparatus and method for producing hydrogen from ammonia by cracking with a microwave resonant plasma torch.

[0004] One aspect of this disclosure provides an apparatus for producing hydrogen from ammonia by cracking with a microwave resonant plasma torch, comprising: a microwave unit adapted to generate microwaves; a reaction unit connected to the microwave unit, the reaction unit including a resonant torch, the resonant torch including: a shell having a closed end and an open end, a resonant cavity formed between the closed end and the open end, an air inlet provided on the outer wall of the shell communicating with the resonant cavity, the air inlet being adapted to communicate with an external ammonia gas source; a central electrode disposed within the resonant cavity; microwaves are fed into the resonant cavity from the closed end to generate microwave resonance, and a plasma region is formed around the tip of the central electrode near the open end, so that ammonia gas flowing in from the air inlet undergoes a cracking reaction when passing through the plasma region, generating cracked gas containing hydrogen.

[0005] According to an embodiment of this disclosure, the length of the central electrode is configured to be one-quarter of the wavelength of the microwave.

[0006] According to embodiments of this disclosure, the reaction unit further includes a tubular component, one end of which is connected to the open end of the housing to output the pyrolysis gas from the other end of the tubular component.

[0007] According to an embodiment of this disclosure, the tip of the central electrode extends into a tubular component, and the inner diameter of the tubular component matches the diameter of the plasma region.

[0008] According to embodiments of this disclosure, there are multiple air inlets, which are evenly distributed on the outer wall of the housing at the same height.

[0009] According to embodiments of this disclosure, the resonant torch further includes a radio frequency connector, which is detachably connected to the closed end of the housing and connected to the center electrode. The radio frequency connector is suitable for feeding microwaves emitted by the microwave unit into the resonant cavity. A magnetic coupling element is disposed in the resonant cavity, with one end of the magnetic coupling element connected to the center electrode and the other end of the magnetic coupling element connected to the inner wall of the radio frequency connector.

[0010] According to embodiments of this disclosure, the radio frequency connector and the center electrode are configured as an integrated structure.

[0011] According to embodiments of this disclosure, the device further includes a detection unit disposed downstream of the reaction unit, the detection unit being adapted to receive the pyrolysis gas from the reaction unit and to detect the concentration of residual ammonia in the pyrolysis gas.

[0012] According to embodiments of this disclosure, it further includes: a dual directional coupler disposed between the microwave unit and the reaction unit, the dual directional coupler being suitable for detecting the microwave power output from the microwave unit to the reaction unit.

[0013] Another aspect of this disclosure provides a method for producing hydrogen from ammonia by cracking with a microwave resonant plasma torch, comprising: feeding microwaves into a resonant cavity, causing the microwaves to resonate within the cavity and forming a plasma region around the tip of a central electrode; inputting ammonia gas into the resonant cavity, causing a cracking reaction to occur as the ammonia gas flows through the plasma region, generating a cracked gas containing hydrogen; detecting the concentration of residual ammonia gas in the cracked gas; and adjusting the ammonia gas intake rate and / or the microwave power based on the concentration of residual ammonia gas to obtain a cracked gas containing hydrogen of a target concentration.

[0014] According to the microwave resonant plasma torch ammonia-to-hydrogen device provided in this disclosure, microwaves resonate within the resonant cavity and a central electrode, forming a high-energy plasma at the tip of the central electrode. The plasma, containing numerous charged particles, collides and reacts with other particles, providing a highly reactive atmosphere for the chemical reaction. This causes the NH bonds in the ammonia molecules to break, achieving efficient ammonia cracking and producing large quantities of hydrogen and nitrogen, with rapid response capabilities. Furthermore, this hydrogen production device does not require a large high-temperature heat source, is compact, easy to install, and suitable for mobile power sources such as automobiles, ships, and aircraft. Moreover, this hydrogen production device primarily relies on the chemical reactivity of the high-energy plasma, thereby reducing dependence on catalysts. Attached Figure Description

[0015] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0016] Figure 1 This schematic diagram illustrates the overall structure of an apparatus for producing hydrogen from ammonia by cracking a microwave resonant plasma torch according to an embodiment of the present disclosure.

[0017] Figure 2 A schematic diagram of the structure of a reaction unit according to an embodiment of the present disclosure is shown.

[0018] Figure 3 This schematic diagram illustrates the overall structure of an apparatus for producing hydrogen from ammonia by cracking a microwave resonant plasma torch according to another embodiment of the present disclosure.

[0019] Figure 4 A flowchart illustrating a method for producing hydrogen from ammonia by cracking with a microwave resonant plasma torch according to an embodiment of the present disclosure is shown.

[0020] Figure Labels

[0021] 1. Microwave unit;

[0022] 2. Reaction unit;

[0023] 21. Resonant torch;

[0024] 211. Shell;

[0025] 212. Resonant cavity;

[0026] 213. Central electrode;

[0027] 214. Radio frequency connectors;

[0028] 215. Magnetic coupling components;

[0029] 216. Air intake;

[0030] 22. Tubular components;

[0031] 23. Fixed flange;

[0032] 24. Tighten the bolts;

[0033] 3. Dual directional couplers;

[0034] 31. Microwave input port;

[0035] 32. Microwave output port;

[0036] 33. Forward power sampling port;

[0037] 34. Reverse power sampling port;

[0038] 35. Forward microwave power meter;

[0039] 36. Reverse microwave power meter;

[0040] 4. Detection unit. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0042] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0043] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0044] When using expressions such as "at least one of A, B, and C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C. Similarly, when using expressions such as "at least one of A, B, or C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C.

[0045] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this disclosure.

[0046] Figure 1 A schematic diagram of the overall structure of a hydrogen production apparatus according to an embodiment of the present disclosure is shown.

[0047] According to the microwave resonant plasma torch pyrolysis apparatus for hydrogen production from ammonia provided in this disclosure, such as... Figure 1 As shown, the hydrogen production device includes a microwave unit 1 and a reaction unit 2. Microwave unit 1 is used to generate microwaves. Reaction unit 2 is connected to microwave unit 1 and includes a resonant torch 21. The resonant torch 21 includes a housing 211 and a central electrode 213. The housing 211 has a closed end and an open end, forming a resonant cavity 212 between the closed end and the open end. An air inlet communicating with the resonant cavity 212 is provided on the outer wall of the housing 211, and the air inlet is suitable for connecting to an external ammonia gas source. The central electrode 213 is disposed within the resonant cavity 212. Microwaves are fed into the resonant cavity 212 from the closed end, causing microwave resonance and forming a plasma region around the tip of the central electrode 213 near the open end. This causes the ammonia gas flowing in from the air inlet to undergo a cracking reaction as it passes through the plasma region, generating cracked gas containing hydrogen.

[0048] Microwave unit 1 may include a microwave source and a transmission device. The microwave source is used to generate microwaves and may employ a magnetron to significantly reduce the cost of the hydrogen production device. The transmission device may be, for example, a waveguide or radio frequency cable, to transmit the generated microwave energy to reaction unit 2. Furthermore, to accommodate the different reaction requirements of reaction unit 2, microwave unit 1 may also be equipped with a power control device to adjust the output power of the microwave source.

[0049] The housing 211 of the resonant torch 21 can be made of a high-temperature resistant and highly conductive material, such as copper. The housing 211 may be, but is not limited to, being tubular or rectangular with a cavity. One end of the housing 211 is closed as a closed end, and the other end has an opening as an open end, forming a semi-closed resonant cavity between the closed end and the open end. The center electrode 213 is positioned on the central axis of the resonant cavity. In this configuration, the housing 211 acts as the outer conductor, and the center electrode acts as the inner conductor, causing the microwaves to resonate within the resonant cavity when microwaves are fed in.

[0050] When microwaves matching the natural frequency of the resonant cavity 212 are fed into the resonant cavity 212, the microwave energy forms a standing wave inside the cavity 212. This standing wave is a wave in which the amplitude of the electromagnetic wave remains constant during propagation, while the phase changes periodically with spatial position. Within the standing wave, the electric and magnetic field strengths reach their maximum at specific locations, forming a high-intensity electric or magnetic field region. Therefore, by inserting the central electrode 213 into the resonant cavity 212, with its tip positioned in the region where the electric field strength is maximum, the tip structure of the central electrode 213 allows for a high concentration of electric field energy around its tip, forming a high-intensity electric field region. This high-intensity electric field ionizes the surrounding gas molecules, generating a plasma composed of numerous charged and neutral particles, thus forming a plasma region around the tip of the central electrode 213.

[0051] Because plasma contains a large number of charged particles with energy, it collides and reacts with other particles, creating a highly active chemical reaction environment. When ammonia is transported to the plasma region, the high-energy electrons in the plasma can effectively bombard ammonia molecules, breaking their internal NH bonds, thereby causing the ammonia molecules to decompose into nitrogen and hydrogen.

[0052] In this embodiment, microwaves resonate within the resonant cavity 212 and the central electrode 213, forming a high-energy plasma at the tip of the central electrode. The highly reactive atmosphere within the plasma enables the effective breaking of the NH bonds in ammonia molecules, achieving efficient ammonia cracking and producing large quantities of hydrogen and nitrogen, exhibiting rapid response capabilities. Furthermore, this hydrogen production device does not require a large, high-temperature heat source, is compact, and easy to install, making it suitable for mobile power sources such as automobiles, ships, and aircraft. Moreover, this hydrogen production device primarily relies on the chemical reactivity of the high-energy plasma, thereby reducing dependence on catalysts.

[0053] According to an embodiment of this disclosure, the length of the central electrode 213 is configured to be one-quarter of the wavelength of the microwave.

[0054] Specifically, a quarter-wavelength center electrode 213 is inserted into the resonant cavity 212 to form a quarter-wavelength resonant cavity. One end of the quarter-wavelength center electrode is connected to the outer shell, and the other end (i.e. the tip) is open. At this time, the electric field intensity at the tip of the center electrode is extremely high, which can concentrate energy to act directly on gas molecules, thereby improving ionization efficiency.

[0055] This disclosure is not limited thereto. In some embodiments, the length of the central electrode 213 can also be configured to be half the wavelength of a microwave. Inserting the half-wavelength central electrode 213 into the resonant cavity constitutes a half-wavelength resonant cavity. In this case, the two ends of the central electrode 213 are located at the antinodes of the standing wave (the region with the strongest electric field), and the electric field intensity at the two ends of the central electrode is the greatest, resulting in a high electric field region at the tip of the central electrode. This effectively accelerates electrons, promotes the ionization of ammonia gas, and thus efficiently generates plasma.

[0056] In some embodiments, the resonant cavity 212 can also be changed to a capacitor-loaded microwave resonant cavity, which can also generate plasma to crack ammonia to produce hydrogen.

[0057] Figure 2 A schematic diagram of the structure of reaction unit 2 according to an embodiment of the present disclosure is shown.

[0058] According to embodiments of this disclosure, such as Figure 2 As shown, the reaction unit 2 also includes a tubular component 22, one end of which is connected to the open end of the housing 211 to output the pyrolysis gas from the other end of the tubular component 22.

[0059] Specifically, the shell 211 has an opening at its open end, and one end of the tubular component 22 can be connected to this opening, so that the resonant cavity 212 and the tubular component 22 are connected. Thus, the pyrolysis gas can be output from the other end of the tubular component 22 using the tubular component 22.

[0060] In some embodiments, such as Figure 2 As shown, a fixing flange 23 can be fitted on the outside of the tubular component 22, and the housing 211 and the fixing flange 23 can be fixed by fastening bolts 24, so that the tubular component 22 and the resonant cavity 212 can be tightly connected.

[0061] Preferably, the tubular component 22 can be a quartz tube with a quartz tubing cavity inside, through which the pyrolysis gas flows out. This disclosure is not limited to this; the tubular component 22 can also be made of high-temperature resistant plastic or glass.

[0062] According to embodiments of this disclosure, such as Figure 2As shown, the tip of the central electrode 213 extends into the tubular component 22, and the inner diameter of the tubular component 22 matches the diameter of the plasma region.

[0063] Specifically, the tip of the center electrode 213 can be approximately flush with the open end of the housing 211, and at least a portion of the tubular component 22 is embedded in the resonant cavity 212, such that the tip of the center electrode 213 extends into the tubular component 22. This disclosure is not limited thereto; the center electrode 213 can also be slightly higher or slightly lower than the open end of the housing 211, as long as the tip of the center electrode 213 extends into the tubular component 22.

[0064] Preferably, the inner diameter of the tubular component 22 is consistent with the maximum outer diameter of the plasma region.

[0065] In this embodiment, when ammonia flows from the inlet to the open end, it flows into the tubular component 22. The ammonia flow is constrained by the inner wall of the tubular component 22. Since the tip of the central electrode 213 is located inside the tubular component 22, and the inner diameter of the tubular component 22 matches the outer diameter of the shell 211, it can be ensured that when ammonia molecules flow through the plasma region, they collide with electrons in the plasma as much as possible and undergo a cracking reaction, thereby improving the cracking efficiency of ammonia.

[0066] According to embodiments of this disclosure, such as Figure 2 As shown, the outer wall of the housing 211 may be provided with multiple air inlets 216, which are evenly distributed on the outer wall of the housing 211 at the same height.

[0067] Specifically, the air inlet 216 can be located on the outer wall of the housing 211 near the closed end, forming an air intake channel with the resonant cavity 212. Each air inlet 216 is connected to an external ammonia gas source to input ammonia gas into the resonant cavity 212. When ammonia gas is input into the resonant cavity 212, each air inlet 216 can input the same gas flow rate into the resonant cavity 212 to form a stable ammonia gas flow in the resonant cavity 212.

[0068] In some embodiments, such as Figure 2 As shown, there can be two air inlets 216, which can be symmetrically arranged on the outer wall of the housing 211. In some embodiments, there can also be three or four air inlets 216, which are evenly distributed on the outer wall of the housing 211 at the same height.

[0069] In this implementation, multiple evenly distributed air inlets 216 ensure uniform gas distribution within the torch tube, forming a stable airflow field. This helps reduce turbulence and vortices within the casing 211, preventing the plasma from being disturbed by unstable ammonia gas flow, thereby improving plasma stability.

[0070] According to embodiments of this disclosure, such as Figure 2 As shown, the resonant torch 21 also includes an RF connector 214, which is detachably connected to the closed end of the housing 211 and connected to the center electrode 213. The RF connector 214 is suitable for feeding microwaves emitted by the microwave unit 1 into the resonant cavity 212.

[0071] In some embodiments, the RF connector 214 is pluggably connected to the closed end of the housing 211. Specifically, the RF connector 214 is provided with an interface or plug, and correspondingly, the closed end of the housing 211 is provided with a matching interface or socket to enable pluggable connection of the RF connector 214.

[0072] The RF connector 214 includes a housing, an inner conductor, and an insulator. The inner conductor is the main channel for transmitting RF signals and can be made of a highly conductive metal material, such as copper or a copper alloy, to ensure low-loss signal transmission. The housing surrounds the inner conductor and serves as shielding against electromagnetic interference and for grounding. The housing can also be made of a metal material with good conductivity and mechanical strength, effectively preventing external electromagnetic interference from affecting the signal. The insulator is located between the inner conductor and the housing, isolating them and preventing signal short circuits and interference. The insulator material is typically selected based on its stable dielectric constant and good temperature resistance to ensure the reliability of the RF connector 214.

[0073] In this implementation, the radio frequency connector 214 serves as a transmission channel between the microwave source and the resonant cavity 212, enabling efficient and stable transmission of microwave signals into the resonant cavity 212.

[0074] According to embodiments of this disclosure, the radio frequency connector 214 and the center electrode 213 are configured as an integrated structure.

[0075] Specifically, the center electrode 213 can be integrated with the inner conductor of the RF connector 214 to reduce contact resistance and signal reflection at the connection point, thereby improving signal transmission efficiency.

[0076] According to an embodiment of the present disclosure, the resonant torch 21 further includes a magnetic coupling element 215 disposed within the resonant cavity 212. One end of the magnetic coupling element 215 is connected to the central electrode 213, and the other end of the magnetic coupling element 215 is connected to the inner wall of the radio frequency connector 214.

[0077] In some embodiments, one end of the magnetic coupling element 215 is soldered to the surface of the center electrode 213 to form a low-impedance path. The other end of the magnetic coupling element 215 is tightly fitted to the metal contacts on the inner wall of the RF connector 214 to ensure efficient magnetic field coupling.

[0078] In some embodiments, the magnetic coupling element 215 may consist of a magnetic core made of a high permeability material (such as ferrite) and an outer copper coil.

[0079] In this implementation, the magnetic coupling element 215 can efficiently couple radio frequency power into the resonant cavity 212 to excite the plasma. Simultaneously, impedance matching can be achieved by adjusting the degree of magnetic coupling, ensuring that radio frequency energy is maximized and transferred to the plasma region while reducing reflection loss.

[0080] Figure 3 The schematic diagram illustrates the overall structure of an apparatus for producing hydrogen from ammonia by cracking a microwave resonant plasma torch according to another embodiment of the present disclosure.

[0081] According to embodiments of this disclosure, such as Figure 3 As shown, in addition to the microwave unit 1 and the reaction unit 2, the hydrogen production device can also be equipped with a detection unit 4. The detection unit 4 can be located downstream of the reaction unit 2. The detection unit 4 is suitable for receiving the cracked gas from the reaction unit 2 and detecting the concentration of residual ammonia in the cracked gas.

[0082] In some embodiments, the detection unit 4 may be connected to the other end of the tubular component 22 in the reaction unit 2. An electrochemical sensor probe may be installed within the detection unit 4 to detect the ammonia concentration in the cracked gas. Specifically, when the cracked gas passes through the electrochemical sensor, an electrochemical reaction occurs on the surface of the electrochemical sensing electrode, generating a current signal proportional to the residual ammonia concentration, which is then converted into the residual ammonia concentration value by an amplification circuit.

[0083] In this implementation, by setting up a detection unit 4 in the hydrogen production unit to detect the concentration of residual ammonia in the cracked gas downstream of the reaction unit 2, the hydrogen production process can be adjusted and optimized, such as by adjusting the ammonia intake or adjusting the microwave power, to improve hydrogen production efficiency and product quality.

[0084] According to embodiments of this disclosure, such as Figure 3 As shown, in addition to the microwave unit 1, reaction unit 2, and detection unit 4, the hydrogen production device also includes a dual-directional coupler 3. The dual-directional coupler 3 is located between the microwave unit 1 and the reaction unit 2, and is used to detect the microwave power output from the microwave unit 1 to the reaction unit 2.

[0085] Specifically, the dual directional coupler 3 includes a microwave input port 31, a microwave output port 32, a forward power sampling port 33, a reverse power sampling port 34, a forward microwave power meter 35, and a reverse microwave power meter 36. The microwave unit 1 is connected to the microwave input port 31, and the microwave output port 32 is connected to the RF connector 214. The forward microwave power is collected at the forward power sampling port 33 using the forward microwave power meter 35, and the reverse microwave power is collected at the reverse power sampling port 34 using the reverse microwave power meter 36.

[0086] In some embodiments, microwave components such as RF connectors and dual directional couplers are impedance matched to the microwave source. For example, the characteristic impedance of microwave components such as RF connectors and dual directional couplers is 50Ω to reduce reflection loss.

[0087] In this implementation, the dual directional coupler 3 can monitor the microwave power output from microwave unit 1 to reaction unit 2 in real time and accurately. This helps operators understand the operating status of the microwave unit in a timely manner, ensuring that microwave energy is delivered to reaction unit 2 in the expected way. It also ensures that the microwave power fluctuates within a set range, thereby maintaining the stability of reaction conditions and improving the controllability of the hydrogen production process.

[0088] According to the hydrogen production device provided in this disclosure, the overall device is small in size, easy to carry and install, and mainly relies on the chemical reactivity of high-energy plasma to efficiently crack ammonia, thereby achieving efficient hydrogen production and reducing dependence on catalysts.

[0089] This disclosure also provides a method for producing hydrogen from ammonia by cracking with a microwave resonant plasma torch, the method comprising operations S410 to S440.

[0090] In operation S410, microwaves are fed into the resonant cavity, causing microwave resonance to occur within the resonant cavity 212, and forming a plasma region around the tip of the central electrode 213.

[0091] In operation S420, ammonia gas is introduced into the resonant cavity 212, causing ammonia gas to undergo a cracking reaction as it flows through the plasma region, generating cracked gas containing hydrogen.

[0092] During operation S430, the concentration of residual ammonia in the cracked gas is detected.

[0093] In operation S440, the intake flow rate of ammonia and / or the power of the microwave are adjusted based on the concentration of residual ammonia to obtain cracked gas with a target concentration of hydrogen.

[0094] In some embodiments, microwave unit 1 generates microwaves. Microwave energy is input into dual directional coupler 3 through microwave input port 31. The sampled forward microwave power and reverse microwave power are output through forward power sampling port 33 and reverse power sampling port 34, respectively. The power values ​​are read by forward microwave power meter 35 and reverse microwave power meter 36, respectively. Microwave energy is output through microwave output port 32 of dual directional coupler 3. The microwave energy is fed into microwave resonant cavity 212 through radio frequency connector 214 and magnetic coupling element 215. The microwaves resonate in microwave resonant cavity 212, forming plasma at the tip of central electrode 213. Ammonia gas enters microwave resonant cavity 212 through gas feed interface and is confined near the tip of central electrode 213 by tubular element 22. After passing through the plasma region, ammonia gas undergoes a cracking reaction. The cracked product gas enters detection unit 4 and residual ammonia gas concentration is monitored. The power of microwave unit 1 and ammonia gas flow rate are adjusted according to residual ammonia gas concentration to ensure optimal cracking conditions.

[0095] The method for producing hydrogen from ammonia by cracking with a microwave resonant plasma torch disclosed herein utilizes microwave resonance within a resonant cavity 212 to generate high-energy plasma at the tip of the central electrode 213. This plasma enables efficient ammonia cracking, producing large quantities of hydrogen and nitrogen. The method offers advantages such as fast response, high cracking rate, low energy consumption, low cost, and small, portable device size. This method has broad application prospects in hydrogen production, particularly in scenarios requiring rapid, efficient, and low-energy hydrogen production, such as internal combustion engines and fuel cells.

[0096] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A device for producing hydrogen from ammonia by cracking with a microwave resonant plasma torch, characterized in that, include: Microwave unit (1), suitable for generating microwaves; A reaction unit (2) is connected to the microwave unit (1). The reaction unit (2) includes a resonant torch (21), which includes: The housing (211) has a closed end and an open end, and a resonant cavity (212) is formed between the closed end and the open end. The outer wall of the housing (211) is provided with an air inlet (216) that communicates with the resonant cavity (212). The air inlet (216) is suitable for connecting to an external ammonia gas source. The center electrode (213) passes through the resonant cavity (212) and is located on the central axis of the resonant cavity; The shell is made of a conductive material and serves as the outer conductor, while the central electrode serves as the inner conductor. Microwaves, which match the inherent frequency of the resonant cavity, are fed into the resonant cavity (212) from the closed end to generate microwave resonance. A plasma region is formed around the tip of the central electrode (213) near the open end, so that ammonia gas flowing in from the air inlet (216) undergoes a cracking reaction when passing through the plasma region, generating cracked gas containing hydrogen. The reaction unit (2) also includes a tubular component (22), one end of which is connected to the open end of the housing (211) to output the pyrolysis gas from the other end of the tubular component (22); The tip of the central electrode (213) extends into the tubular component (22), and the inner diameter of the tubular component (22) matches the diameter of the plasma region.

2. The apparatus according to claim 1, characterized in that, The length of the central electrode (213) is configured to be one-quarter of the wavelength of the microwave.

3. The apparatus according to claim 1, characterized in that, The air inlets (216) include multiple inlets, which are evenly distributed on the outer wall of the housing (211) at the same height.

4. The apparatus according to claim 1, characterized in that, The resonant torch (21) also includes: Radio frequency connector (214) is detachably connected to the closed end of the housing (211) and connected to the center electrode. The radio frequency connector (214) is adapted to feed microwaves emitted by the microwave unit into the resonant cavity (212). A magnetic coupling element (215) is disposed in the resonant cavity (212). One end of the magnetic coupling element (215) is connected to the center electrode (213), and the other end of the magnetic coupling element (215) is connected to the inner wall of the radio frequency connector (214).

5. The apparatus according to claim 4, characterized in that, The radio frequency connector (214) and the center electrode (213) are constructed as an integrated structure.

6. The apparatus according to any one of claims 1 to 5, characterized in that, Also includes: The detection unit (4) is located downstream of the reaction unit (2). The detection unit (4) is adapted to receive the cracked gas from the reaction unit (2) and detect the concentration of residual ammonia in the cracked gas.

7. The apparatus according to any one of claims 1 to 5, characterized in that, Also includes: A dual directional coupler (3) is disposed between the microwave unit (1) and the reaction unit (2). The dual directional coupler (3) is suitable for detecting the microwave power output by the microwave unit (1) to the reaction unit.

8. A method for producing hydrogen from ammonia by cracking with a microwave resonant plasma torch based on the apparatus of any one of claims 1 to 7, characterized in that, include: Microwaves matching the inherent frequency of the resonant cavity are fed into the resonant cavity (212), causing the microwaves to resonate within the resonant cavity (212) and forming a plasma region around the tip of the central electrode (213). Ammonia gas is introduced into the resonant cavity (212), causing the ammonia gas to undergo a cracking reaction when it flows through the plasma region, generating cracked gas containing hydrogen. The concentration of residual ammonia in the pyrolysis gas was detected; Based on the concentration of the residual ammonia, the intake rate of the ammonia and / or the power of the microwave are adjusted to obtain cracked gas with a target concentration of hydrogen.

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