Fluidized bed membrane reactor for hydrogen production by methane cracking and method for hydrogen production by methane cracking

Abstract

This invention provides a fluidized bed membrane reactor and method for methane cracking to produce hydrogen, comprising a reactor shell, a hollow fiber membrane bundle, a carbon-carrying medium filled within the lower shell, and a carbon collection mechanism. The reactor shell includes an upper shell and a lower shell separated from each other. The upper shell has a hydrogen outlet at its top, and the lower shell has a reaction tail gas outlet and a methane inlet on its side wall. The lower shell has a material outlet at its bottom. The hollow fiber membrane bundle is disposed within the reactor shell and includes a reaction layer and a separation layer arranged sequentially from the outside to the inside. The outer side of the reaction layer and the internal chamber of the lower shell together form a reaction chamber, and the separation layer and the internal chamber of the upper shell together form a separation chamber. The carbon collection mechanism includes a carbon collection bin, which is connected to the material outlet. Compared with the prior art, this invention solves the technical problem that hydrogen separation and purification and carbon product separation cannot be performed simultaneously in existing methane cracking to produce hydrogen.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen production, and more specifically, relates to a fluidized bed membrane reactor for hydrogen production by methane cracking. This invention also relates to a method for hydrogen production by methane cracking. Background Technology

[0002] Hydrogen energy, due to its cleanliness, renewability, and high energy density, is considered a core component of the future energy system. Currently, large-scale industrial hydrogen production mainly relies on steam reforming or partial oxidation technologies for fossil fuels. These methods not only produce hydrogen with low purity, requiring complex purification steps to meet the demands of high-end applications such as fuel cells, but also generate large amounts of carbon dioxide during production, leading to serious carbon emission problems.

[0003] Methane cracking for hydrogen production is a highly promising alternative technology. Theoretically, this reaction produces only hydrogen and solid carbon, without generating carbon dioxide, thus directly preventing carbon emissions at the source. Simultaneously, the byproduct solid carbon (such as carbon nanotubes and carbon black) has high economic value, effectively reducing the overall cost of hydrogen production.

[0004] However, methane cracking technology faces two major challenges: First, non-catalytic cracking requires extremely high reaction temperatures (typically above 1200°C), resulting in enormous energy consumption. Second, while introducing a catalyst can lower the reaction temperature, the carbon produced in the reaction quickly coats the active sites of the catalyst and the inner wall of the reactor, leading to rapid catalyst deactivation. Furthermore, the carbon deposits are difficult to remove continuously and effectively from the reaction system, making the reaction unstable and unsustainable. In addition, the reaction products are a mixture of hydrogen, unreacted methane, and carbon powder, requiring additional separation and purification equipment to obtain high-purity hydrogen, increasing the system's complexity and cost.

[0005] Therefore, how to solve the problems of carbon buildup leading to catalyst deactivation and the need for additional hydrogen separation and purification in the existing methane cracking hydrogen production process has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a fluidized bed membrane reactor for methane cracking to produce hydrogen, so as to solve the technical problem that hydrogen separation and purification and carbon product separation cannot be carried out simultaneously in existing methane cracking to produce hydrogen, thereby achieving stable and efficient continuous production and reducing hydrogen production costs.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a fluidized bed membrane reactor for methane cracking to produce hydrogen, comprising:

[0008] The reactor shell includes an upper shell and a lower shell that are separated from each other. The top of the upper shell is provided with a hydrogen outlet, the side wall of the lower shell is provided with a reaction tail gas outlet and a methane inlet, and the bottom of the lower shell is provided with a material outlet.

[0009] A hollow fiber membrane bundle is disposed inside the reactor shell and includes a reaction layer and a separation layer arranged sequentially from the outside to the inside. The outer side of the reaction layer and the inner wall of the lower shell together form a reaction cavity, and the inner side of the separation layer and the inner wall of the upper shell together form a separation cavity.

[0010] The lower shell is filled with a carbon-carrying medium;

[0011] The carbon collection mechanism includes a carbon collection bin connected to the material discharge outlet.

[0012] In one possible implementation, the carbon collection mechanism further includes a screen disposed between the material discharge outlet and the carbon collection bin;

[0013] The aperture of the screen is smaller than the diameter of the carbon-carrying medium. As the screen vibrates, the carbon products adsorbed on the surface of the carbon-carrying medium fall off and pass through the screen into the carbon collection bin.

[0014] In one possible implementation, the carbon collection mechanism further includes a screen disposed between the material discharge outlet and the carbon collection bin;

[0015] The aperture of the screen is larger than the diameter of the carbon-carrying medium. As the screen vibrates, the carbon-carrying medium with carbon products adsorbed on its surface passes through the screen and falls into the carbon collection bin.

[0016] In one possible implementation, the methane cracking hydrogen production fluidized bed membrane reactor further includes a medium feed section located at the top of the lower shell. The medium feed section includes a feed hopper and a feed pipe, and the feed hopper is connected to the lower shell through the feed pipe.

[0017] In one possible implementation, the methane cracking hydrogen production fluidized bed membrane reactor further includes a vibration motor located on the outer wall of the middle portion of the lower shell to cause the side wall of the lower shell to vibrate.

[0018] In one possible implementation, the methane cracking hydrogen production fluidized bed membrane reactor further includes a combustion channel located in the chamber of the lower shell for burning the reaction tail gas and providing heat for methane cracking. The top of the combustion channel is connected to the reaction tail gas outlet of the lower shell, and the bottom of the combustion channel is provided with an exhaust port.

[0019] Compared with existing technologies, the beneficial effects of the fluidized bed membrane reactor for methane cracking to hydrogen production provided by this invention are as follows:

[0020] After methane enters the lower shell through the methane inlet, it undergoes a cracking reaction on the surface of the hollow fiber membrane bundle to produce hydrogen and carbon. The hydrogen permeates through the separation layer of the hollow fiber membrane bundle into the upper shell and exits through the hydrogen outlet. During the methane cracking process, incompletely cracked methane is simultaneously generated in the lower shell as reaction tail gas and exits through the reaction tail gas outlet. At the same time, carbon products deposited on the surface of the hollow fiber membrane bundle are deposited and adhere to the surface of the carbon-carrying medium and are discharged through the material outlet. This achieves in-situ separation of hydrogen from methane cracking and continuous removal of carbon products, reducing the accumulation of carbon products on the reaction side, promoting reaction equilibrium, and improving the reaction rate, hydrogen yield, and purity. These effects solve the technical problems of low hydrogen separation efficiency and easy clogging of the reactor by carbon products in traditional methane cracking reactions.

[0021] In addition to the above-mentioned solutions, this invention also proposes a method for producing hydrogen from methane through cracking. This method is based on the fluidized bed membrane reactor for producing hydrogen from methane through cracking as described above, and the method includes the following steps:

[0022] S1. Methane is introduced into the lower shell, which is filled with carbon-carrying medium and has a sufficient reaction temperature, to carry out a cracking reaction;

[0023] S2. Apply a vacuum to the inner cavity of the upper shell using a vacuum pumping device to allow the hydrogen gas generated in the reaction to permeate and separate.

[0024] S3. The heat from the combustion of the reaction tail gas is introduced into the lower shell to heat the lower shell;

[0025] S4. Intermittently remove carbon products and replenish carbon-carrying media.

[0026] In one possible implementation, step S1 further includes the following steps:

[0027] S101. Adjust the methane feed flow rate and / or the vibration frequency of the reactor shell to control the movement speed of the carbon-carrying medium within the reactor.

[0028] In one possible implementation, in step S1, the reaction temperature is 700℃-1000℃; the feed volume hourly space velocity of methane is 1000 / h-50000 / h.

[0029] In one possible implementation, in step S2, the vacuum level of the inner cavity of the upper housing is 0.001 MPa-0.01 MPa.

[0030] Compared to existing technologies, the methane cracking hydrogen production method of this invention possesses all the advantages of the aforementioned fluidized bed membrane reactor for methane cracking hydrogen production, which will not be elaborated upon here. Furthermore, through the coordinated operation of the above steps, methane is cracked to produce hydrogen under optimized conditions, the hydrogen is rapidly separated through a membrane under vacuum-driven conditions, the tail gas is combusted to provide self-heating, and carbon products are periodically removed. This integration of functions achieves full-process integration and automated control of methane cracking hydrogen production, resulting in the efficient production of high-purity hydrogen, reduced external energy consumption, and carbon resource recovery. Thus, this invention, through the aforementioned effects, solves the technical problems of low hydrogen yield, high energy consumption, and difficult carbon treatment in traditional methane cracking methods. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0032] Figure 1 A schematic diagram of the overall structure of the fluidized bed membrane reactor for methane cracking to produce hydrogen provided by the present invention;

[0033] Figure 2 A schematic diagram showing the connection relationship between the hollow fiber membrane and the fixture in the fluidized bed membrane reactor for methane cracking to produce hydrogen provided by the present invention.

[0034] Figure 3 This is a schematic diagram showing the positional relationship between the combustion channel and the eccentric turbine in the fluidized bed membrane reactor for methane cracking and hydrogen production of the present invention;

[0035] Figure 4 This is a flowchart illustrating the steps of the methane cracking method for hydrogen production in this invention.

[0036] Figure 5 A scanning electron microscope image of a cross-section of a hollow fiber bundle with carbon deposited on its surface;

[0037] Figure 6 This is a scanning electron microscope image of a carbon-supported medium with carbon adhering to its surface.

[0038] In the picture:

[0039] 1. Reactor outer shell; 11. Upper shell; 12. Lower shell;

[0040] 2. Hollow fiber membrane bundle; 21. Reaction layer; 22. Separation layer;

[0041] 3. Carbon-supported medium;

[0042] 4. Combustion passage; 41. Eccentric turbine; 42. Vibration motor;

[0043] 5. Carbon collection mechanism; 51. Carbon collection bin; 52. Screen;

[0044] 6. Fastener; 61. Fixing plate; 62. Nickel alloy solder layer; 63. Sealing sleeve. Detailed Implementation

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0046] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "back" appear, indicating orientation or positional relationship, they are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0047] Furthermore, in the description of this invention, unless otherwise explicitly defined, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0048] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0049] Please refer to the following: Figures 1 to 3 The fluidized bed membrane reactor for methane cracking to hydrogen production provided by the present invention will now be described. This fluidized bed membrane reactor for methane cracking to hydrogen production includes a reactor shell 1, a hollow fiber membrane bundle 2, a carbon-carrying medium 3 and a carbon collection mechanism 5 filled within a lower shell 12. The reactor shell 1 includes an upper shell 11 and a lower shell 12 separated from each other. The upper shell 11 has a hydrogen outlet at its top, and the lower shell 12 has a reaction tail gas outlet and a methane inlet on its side wall. The lower shell 12 has a material outlet at its bottom. The hollow fiber membrane bundle 2 is disposed within the reactor shell 1 and includes a reaction layer 21 and a separation layer 22 arranged sequentially from the outside to the inside. The outer side of the reaction layer 21 and the internal chamber of the lower shell 12 together form a reaction chamber, and the separation layer 22 and the internal chamber of the upper shell 11 together form a separation chamber. The carbon collection mechanism 5 includes a carbon collection bin 51, which is connected to the material outlet.

[0050] In the specific implementation process of the above embodiment, after methane enters the lower shell 12 from the methane inlet, it undergoes a cracking reaction on the surface of the hollow fiber membrane bundle 2 to generate hydrogen and carbon. The hydrogen permeates through the separation layer 22 of the hollow fiber membrane bundle 2 to the upper shell 11 and is discharged from the hydrogen outlet.

[0051] In the above reaction process, the carbon products deposited on the surface of the hollow fiber membrane bundle 2 adhere to the surface of the carbon-supporting medium 3 and are discharged through the material outlet. This achieves in-situ separation of hydrogen from methane cracking and continuous removal of carbon products, reducing the accumulation of carbon products on the reaction side, promoting reaction equilibrium, and improving the reaction rate, hydrogen yield, and purity. Thus, this invention solves the technical problems of low hydrogen separation efficiency and easy reactor clogging by carbon products in traditional methane cracking reactions.

[0052] In addition to the feasible implementation methods described above, the carbon collecting mechanism 5 also includes a screen 52, which is located between the material discharge outlet and the carbon collecting bin 51. When the aperture of the screen 52 is smaller than the diameter of the carbon-carrying medium 3, the carbon product falls off the surface of the carbon-carrying medium 3 through the vibration of the screen 52, passes through the screen 52, and falls into the carbon collecting bin 51. With this configuration, this embodiment can prevent the carbon-carrying medium 3 from passing through, allowing only the carbon product to be produced. The screen 52 can be removed when the carbon-carrying medium 3 needs to be replaced. In specific implementations, the aperture of the screen 52 and the diameter of the carbon-carrying medium 3 (e.g., ...) are... Figure 6 As shown in the figure, the diameter of the carbon-carrying medium 3 is 0.5 mm, and the aperture of the screen 52 is less than 0.5 mm.

[0053] Based on the above embodiments, in another implementation, the aperture of the screen 52 is larger than the diameter of the carbon-carrying medium 3. In specific applications, when no vibration is applied to the reactor shell 1 or the screen 52, the screen 52 can hinder the outflow of the carbon-carrying medium 3 due to the aggregation effect of the carbon-carrying medium 3. When the reactor shell 1 or the screen 52 vibrates, the carbon-carrying medium 3 with attached carbon can more easily pass through the aperture of the screen 52 and be discharged. In other words, in this embodiment, the screen 52 simultaneously serves to hinder the outflow of the carbon-carrying medium 3 and control its outflow rate.

[0054] Furthermore, to replenish the carbon-carrying medium 3, the methane cracking hydrogen production fluidized bed membrane reactor also includes a medium feed section located at the top of the lower shell 12. The medium feed section includes a feed hopper and a feed pipe, with the feed hopper connected to the lower shell 12 via the feed pipe. In this way, the medium feeder in this embodiment can work in conjunction with the screen 52 to continuously or intermittently replenish the carbon-carrying medium 3 from the feed hopper through the feed pipe into the lower shell 12, mixing it with the reactants and maintaining a sufficient amount of carbon-carrying medium 3 in the reactor. This configuration allows for convenient replenishment of the carbon-carrying medium 3 and continuous reaction. The carbon-carrying medium feeder reduces downtime, improves reactor operation continuity, and ensures stable reaction efficiency.

[0055] Preferably, to prevent gas leakage from the reactor during the replenishment of the carbon-carrying medium 3, the carbon-carrying medium 3 is fed through an automatic feeder, which is connected to the reactor shell 1 located below via a pipeline. Throughout the feeding process, the flow path of the carbon-carrying medium 3 remains sealed from the outside environment to prevent gas leakage.

[0056] Furthermore, compared to existing fiber bundles, the hollow fiber membrane bundle 2 of this invention has an outer reaction layer 21 that is significantly thicker than the separation layer 22, and both are made of metal alloys. In this embodiment, the reaction layer 21 provides stable support for the entire fiber bundle structure, ensuring sufficient structural strength. With guaranteed structural strength, the hollow fiber membrane bundle 2 in this embodiment can prevent structural damage to the fiber bundle during the movement of the carbon-carrying medium 3. Simultaneously, the flow direction of the carbon-carrying medium 3 in this embodiment is parallel to the extension direction of the fiber bundle, reducing lateral shear force and further preventing damage to the structure of the hollow fiber membrane bundle 2 during the flow of the carbon-carrying medium 3.

[0057] In addition to the feasible implementation methods described above, the methane cracking hydrogen production fluidized bed membrane reactor in this embodiment also includes a combustion channel 4. The combustion channel 4 is located in the chamber of the lower shell 12 and is used to burn the reaction tail gas and provide heat for methane cracking. The top of the combustion channel 4 is connected to the reaction tail gas outlet of the lower shell 12, and the bottom of the combustion channel 4 is provided with an exhaust port.

[0058] In this embodiment, through the above-described configuration, during the methane cracking process to produce hydrogen, incompletely cracked methane is simultaneously generated in the lower shell 12 as reaction tail gas. Under the pressure of the conveying system, the reaction tail gas enters the combustion channel 4 from the reaction tail gas outlet of the lower shell 12 for combustion, providing continuous heat energy to the lower shell 12 to maintain the reaction temperature. As configured above, the combustion channel 4 in this embodiment increases the internal temperature of the reactor, which is beneficial for the continuous operation of the reaction within the reactor. The combustion channel 4 also reduces the heat loss of the reactor, making the reactor more energy-efficient and environmentally friendly.

[0059] In practical implementation, the reaction tail gas may also contain unreacted methane and unseparated hydrogen. This gas is introduced into combustion channel 4 to mix and burn with air. The entire combustion path is from top to bottom, with the top temperature lower than the bottom temperature. The heat distribution within the lower shell 12 shows heat accumulation at the top and a relatively lower temperature at the bottom. This configuration allows this embodiment to utilize the heat from the top to provide temperature for the combustion of the reaction tail gas and air. Combustion channel 4 transports heat to the bottom of the lower shell 12 through the gas combustion flow path, counteracting the blowing of methane onto the carbon-carrying medium 3. This provides heat to the reaction chamber within the lower shell 12 while simultaneously making the temperature distribution within the lower shell 12 more rational.

[0060] Furthermore, regarding the issue that all-carbon materials might clog the reaction layer 21 of the hollow fiber membrane bundle 2, it should be noted that although all-carbon materials (grown carbon nanotubes) may adhere to the surface of the fiber bundle (i.e., the hollow fiber membrane bundle 2), Figure 5 As shown in the figure, however, under the action of the flowing carbon-carrying medium 3, the carbon adhering to its surface will be cleaned up in time by the carbon-carrying medium 3. The thickness of the carbon deposition is far from having a visible impact on the catalysis and separation of hydrogen, and will not have a negative effect on the normal operation of the hollow fiber membrane bundle 2.

[0061] Meanwhile, the carbon element accumulated on the surface of the fiber bundle has a loose and porous structure, and even if there is a certain accumulation of the grown carbon nanotubes, since the diameter of the hydrogen element is much smaller than the gap between the accumulated carbon layers, the hydrogen element after decomposition can easily pass through the carbon layer. Therefore, the carbon layer grown and accumulated on the surface of the fiber bundle will not have a visible impact on the separation of hydrogen.

[0062] To address the issue that long nickel fiber bundles are easily damaged by the flow of the carbon-carrying medium 3 at high temperatures, the hollow fiber membrane bundle 2 in this application can be housed within a small-diameter, high-temperature resistant tubular device. The tubular device itself can provide some fixation and support for the fiber bundle, preventing excessive deformation. Of course, other methods for fixing the hollow fiber membrane bundle 2 to a certain extent are also feasible implementation methods, which will not be elaborated here.

[0063] When the hollow fiber membrane bundle 2 is relatively short, its structural stiffness is sufficient to meet the usage requirements, requiring only fixation at both ends. Furthermore, since the carbon-carrying particles are approximately 0.5 mm in diameter, these particles are extremely unlikely to cause substantial damage to the fiber bundle at normal operating temperatures (generally below 900 degrees Celsius). Moreover, the carbon-carrying particles flow vertically, resulting in minimal radial load on the fiber bundle, allowing it to operate normally at higher temperatures.

[0064] Based on the above embodiments, a feasible implementation method is proposed. The fluidized bed membrane reactor for methane cracking to produce hydrogen further includes a fixing component 6. The fixing component 6 includes a fixing disk 61, a nickel alloy solder layer 62, and a sealing sleeve 63. The fixing disk 61 is provided with an installation hole. The sealing sleeve 63 is sleeved on the outer periphery of the hollow fiber membrane bundle 2 and is located between the hollow fiber membrane bundle 2 and the installation hole. The nickel alloy solder layer 62 is located between the sealing sleeve 63 and the hollow fiber membrane bundle 2.

[0065] In this embodiment, the hollow fiber membrane bundle 2 is inserted into the reactor shell 1 through the mounting hole via the fixing plate 61, the nickel alloy solder layer 62, and the sealing sleeve 63. The sealing sleeve 63 is fitted around the membrane and provides a seal, while the nickel alloy solder layer 62 melts at high temperature to form a strong seal and fixation. This arrangement ensures the airtightness and mechanical stability between the hollow fiber membrane bundle 2 and the reactor shell 1. These functions achieve reliable installation and leak prevention of the hollow fiber membrane bundle 2, improve reactor sealing and durability, reduce hydrogen leakage, prevent material flow between the upper shell 11 and the lower shell 12, and ensure separation efficiency. These technical effects solve the problem of the hollow fiber membrane bundle 2 being prone to loosening, leakage, or damage under high-temperature conditions.

[0066] In addition to the feasible implementation methods described above, to prevent the carbon-carrying medium 3 from becoming stuck in the lower housing 12 after carbon adheres, it is necessary to vibrate the lower housing 12 to enhance the flowability of the carbon-carrying medium 3. Based on this idea, an eccentric turbine 41 driven by the flow of combustion gas is provided in the combustion channel 4. The eccentric turbine 41 is driven to rotate by the combustion gas, and its own center of gravity changes continuously with its rotation, causing the combustion channel 4 to vibrate, which in turn drives the lower housing 12 to vibrate. Combined with the impact of methane, this improves the flow efficiency of the carbon-carrying medium 3 in the lower housing 12.

[0067] In addition to the feasible implementation methods described above, a feasible implementation method is proposed: the methane cracking hydrogen production fluidized bed membrane reactor further includes a vibration motor 42, which is located on the outer wall of the middle part of the lower shell 12. In this embodiment, the vibration motor 42 generates mechanical vibration during operation, which is transmitted to the interior of the lower shell 12, causing the carbon-carrying medium 3 particles to continuously flow and mix, preventing them from agglomerating or depositing. Combined with the screen 52 mentioned above, this allows the carbon-carrying medium 3 or carbon products to be discharged through the vibrating screen 52. Furthermore, the vibrating sidewall also promotes sufficient contact of the carbon-carrying medium 3 and the shedding of carbon products. The vibrating sidewall also helps maintain the dynamic fluidization state of the carbon-carrying medium 3 for a longer period, thereby improving reaction efficiency, enhancing the carbon product removal capacity, and reducing the risk of clogging. These effects solve the technical problems of easy agglomeration of the carbon-carrying medium 3 and poor flow leading to reaction interruption in the fluidized bed reactor.

[0068] Based on the above embodiments, a feasible implementation method is proposed, wherein the carbon-carrying medium 3 is an inert spherical particle or a hollow cylindrical Raschig ring, and the material of the carbon-carrying medium 3 is ceramic, quartz or graphite. The ratio of the diameter of the lower shell 12 to the particle size of the carbon-carrying medium 3 is greater than 100. With this configuration, the carbon-carrying medium 3 serves as a carrier of carbon element in the reactor, and its shape and material ensure high specific surface area, good thermal stability and mechanical strength.

[0069] Further adjustments to the particle size ratio optimize the fluid dynamics of the fluidized bed, resulting in uniform fluidization of the medium.

[0070] The above configuration optimizes the selection of the carbon-carrying medium 3 and ensures stable operation of the fluidized bed. It increases the carbon carrying area, enhances heat transfer efficiency, and reduces medium wear, thus solving the technical problems of low reaction efficiency, rapid wear, or unstable fluidization caused by improper selection of the carbon-carrying medium 3.

[0071] In specific implementation, the process for producing hydrogen from methane through cracking according to the present invention is detailed below:

[0072] Methane is introduced into the lower shell 12 at a mass hourly space velocity (MSV) of 10,000 mH for hydrogen production via cracking. A nickel-based alloy hollow fiber membrane bundle 2 uses a vacuum pump connected to the upper shell 11 to separate hydrogen from the mixed products, maintaining a vacuum of 0.01 MPa. The extracted permeate is hydrogen. The lower shell 12 is filled with solid alumina spheres with a diameter of 0.1 mm at a packing ratio of 1. The combustion channel 4 is loaded with a Pt-Fe / alumina catalyst at a packing volume ratio of 0.85. The sieve 52 has a mesh size of... The mesh size is 2000; the one-end sealed metallic nickel hollow fiber membrane bundle 2 includes 30 hollow fiber membranes (i.e., hollow fiber membrane bundle 2); the control valve is opened to introduce unreacted methane and unpermeated hydrogen into the combustion channel 4 to mix and burn with air; the movable sealing plate of the carbon collection chamber 51 is opened, and under the action of the screen 52, the carbon product is screened out from the carbon-carrying medium 3 and falls into the carbon collection chamber 51 from above; then the movable sealing plate can be closed, and the carbon collection chamber 51 can be opened to remove the carbon product. As the temperature increases from 600℃ to 1000℃, the methane conversion rate increases from 43% to 86%, the carbon product production rate increases from 0.8 mg / min to 18 mg / min, the volume percentage of carbon nanotubes in the product is about 5%, the hydrogen flow rate increases from 4.15 mL / min to 86.1 mL / min, and the hydrogen concentration is always higher than 99.9%.

[0073] When methane is fed into the reactor at a mass hourly space velocity of 20,000 mW / h for cracking and hydrogen production, the vacuum degree of the upper shell 11 is maintained at 0.005 MPa. The metallic nickel hollow fiber membrane bundle 2, which is sealed at one end, consists of 40 hollow fiber membranes. The vibration motor is turned on, and the vibration amplitude of the carbon-carrying particles is controlled at 1.5 mm. At a reaction temperature of 1000 degrees Celsius, the methane conversion rate is 79%, the carbon product production rate is 34.6 mg / min, the hydrogen flow rate is 129.15 mL / min, and the hydrogen concentration is always higher than 99.9%.

[0074] When methane is fed into the reactor at a mass hourly space velocity of 50,000 mH for cracking and hydrogen production, the vacuum degree of the upper shell 11 needs to be maintained at 0.002 MPa. At 1000 °C, the conversion rate of methane is 73%, the carbon product yield rate is 137.4 mg / min, the hydrogen flow rate is 513.2 mL / min, and the hydrogen concentration is always higher than 99.9%.

[0075] Alternatively, in addition to nickel-based alloy hollow fiber membranes, using iron-based hollow fiber membranes is also an optional implementation method, which will not be elaborated here.

[0076] Based on the same inventive concept, in addition to the above-mentioned scheme, this invention also proposes a method for producing hydrogen from methane through cracking. This method is based on the fluidized bed membrane reactor for producing hydrogen from methane through cracking as described above. The method for producing hydrogen from methane through cracking includes the following steps:

[0077] S1. Methane is introduced into the lower shell 12, which is filled with carbon-carrying medium 3 and has a sufficient reaction temperature, to carry out a cracking reaction;

[0078] S2. Apply a vacuum to the inner cavity of the upper shell 11 using a vacuum pumping device to allow the hydrogen gas generated in the reaction to permeate and separate.

[0079] S3. The heat from the combustion of the reaction tail gas is introduced into the lower shell 12 to heat the lower shell 12;

[0080] S4, intermittently remove carbon products and replenish carbon-carrying medium 3.

[0081] In the specific implementation process described above, methane is cracked under optimized conditions to produce hydrogen. The hydrogen is then rapidly separated through a membrane under vacuum-driven conditions. The tail gas is combusted to provide self-heating, and carbon products are periodically removed. These functions achieve full-process integration and automated control of methane cracking for hydrogen production, resulting in the efficient production of high-purity hydrogen, reduced external energy consumption, and carbon resource recovery. This helps to solve the technical problems of low hydrogen yield, high energy consumption, and difficult carbon processing in traditional methane cracking methods.

[0082] Based on the above embodiments, a feasible implementation method is proposed, in which step S1 further includes the following steps:

[0083] S101. Adjust the methane feed flow rate and / or the vibration frequency of the reactor shell 1 to control the movement speed of the carbon-carrying medium 3 in the reactor.

[0084] This setup, by adjusting the feed flow rate to regulate reactant concentration and residence time, and simultaneously regulating the vibration frequency to optimize the fluidization degree and mixing efficiency of the carbon-carrying medium 3, achieves dynamic and precise control of reaction conditions. Consequently, this embodiment achieves the technical effects of improving methane conversion rate, optimizing hydrogen yield, and preventing medium deposition. These effects solve the technical problems of low reaction efficiency or excessive carbon product accumulation caused by inflexible reaction parameters.

[0085] Based on the above embodiments, a feasible implementation method is proposed. In step S1, the reaction temperature is 700℃-1000℃; the methane feed volume hourly space velocity (VHSV) is 1000 / h-50000 / h. In this step, the methane cracking reaction rate is accelerated at high temperatures, and the VHSV adjustment ensures sufficient residence time for the reactants to achieve high conversion rates, while avoiding over-reaction or byproduct formation. The combination of these functions achieves an optimized balance of reaction conditions, improving hydrogen yield and selectivity, and reducing carbon deposition and side reactions.

[0086] Based on the above embodiments, a feasible implementation method is proposed. In step S2, the vacuum degree of the inner cavity of the upper shell 11 is 0.001 MPa-0.01 MPa. The vacuum pumping device reduces the partial pressure of hydrogen, creating a pressure difference that drives hydrogen to rapidly permeate from the separation layer 22 of the hollow fiber membrane bundle 2 to the upper layer. This configuration enhances the mass transfer efficiency of hydrogen, achieving efficient separation and purification of hydrogen. Thus, this embodiment achieves the technical effects of improving hydrogen recovery rate and product purity, and reducing residual gas.

[0087] In summary, by setting up an integrated structure and supporting methods for a fluidized bed membrane reactor for methane cracking to produce hydrogen, this invention achieves efficient coordination and optimization of the entire process from reaction and separation to carbon removal, ultimately achieving significant technical effects in improving hydrogen yield and purity and ensuring process continuity. It systematically solves many technical problems existing in traditional methane cracking technology.

[0088] Specifically, the upper and lower partition design of the reactor shell 1, combined with the hollow fiber membrane bundle 2 which has both reaction and separation functions, allows the methane in the lower shell 12 to be efficiently cracked on the surface of the carbon-supported medium 3 during operation. The generated hydrogen is selectively extracted in situ from the reaction layer 21 to the separation layer 22 and collected in the upper shell 11 for discharge. This combination not only enhances the mass transfer and separation efficiency but also effectively shifts the cracking reaction equilibrium to the right, thereby solving the problems of low hydrogen separation efficiency and limited reaction conversion rate.

[0089] Combustion channel 4 cleverly introduces and combusts unreacted exhaust gases and other components, releasing heat that directly provides a continuous and stable heat source for the strongly endothermic pyrolysis reaction in the lower shell 12. This forms an efficient internal circulation thermal management system, solving the technical dilemmas of high external heating energy consumption and difficulty in maintaining a uniform and stable reaction temperature. The carbon collection mechanism 5 is linked with the vibration motor 42 and the media feed section. Through mechanical vibration, it maintains the fluidization state of the carbon-carrying medium 3 to prevent caking and allows intermittent removal of the medium with attached carbon products and replenishment with fresh medium, or only allows the discharge of carbon products. Combined with optimized media morphology and particle size control, this ensures that the reactor can operate continuously and stably for a long time, fundamentally solving the problems of reactor blockage and frequent shutdowns caused by carbon buildup.

[0090] Furthermore, the fixture 6 forms a reliable seal at high temperatures through a nickel alloy solder layer 62, ensuring the long lifespan and safety of the membrane module under harsh operating conditions. Based on this reactor structure, the hydrogen production method, through the coordinated control of key parameters such as reaction temperature, feed space velocity, vacuum degree, and fluidization state of the medium, enables the entire system to operate under optimal conditions. This not only maximizes hydrogen yield and purity but also minimizes process energy consumption and achieves orderly management of carbon byproducts, ultimately comprehensively solving a series of core technical bottlenecks in traditional technologies, such as low efficiency, high energy consumption, discontinuous operation, and difficulties in carbon processing. It provides an efficient, economical, and reliable solution for green and low-carbon hydrogen production.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fluidized bed membrane reactor for methane cracking to produce hydrogen, characterized in that, include: The reactor shell (1) includes an upper shell (11) and a lower shell (12) that are separated from each other. The upper shell (11) is provided with a hydrogen outlet at the top, and the lower shell (12) is provided with a reaction tail gas outlet and a methane inlet on the side wall. The lower shell (12) is provided with a material outlet at the bottom. Hollow fiber membrane bundle (2) is disposed inside the reactor shell (1) and includes a reaction layer (21) and a separation layer (22) arranged sequentially from the outside to the inside. The outer side of the reaction layer (21) and the inner wall of the lower shell (12) together form a reaction cavity, and the inner side of the separation layer (22) and the inner wall of the upper shell (11) together form a separation cavity. The lower shell (12) is filled with a carbon-carrying medium (3). The carbon collection mechanism (5) includes a carbon collection bin (51) connected to the material discharge outlet. The methane cracking hydrogen production fluidized bed membrane reactor also includes a combustion channel (4), which is located in the chamber of the lower shell (12) for burning the reaction tail gas and providing heat for methane cracking. The top of the combustion channel (4) is connected to the reaction tail gas outlet of the lower shell (12), and the bottom of the combustion channel (4) is provided with an exhaust port. The combustion channel (4) is equipped with an eccentric turbine (41) driven by the flow of combustion gas. The eccentric turbine (41) is driven to rotate by the combustion gas, and its center of gravity changes continuously with its rotation, causing the combustion channel (4) to vibrate, which in turn drives the lower shell (12) to vibrate.

2. The fluidized bed membrane reactor for methane cracking to hydrogen production as described in claim 1, characterized in that, The carbon collection mechanism (5) also includes a screen (52), which is located between the material discharge port and the carbon collection bin (51); The aperture of the screen (52) is smaller than the diameter of the carbon-carrying medium (3). As the screen (52) vibrates, the carbon products adsorbed on the surface of the carbon-carrying medium (3) fall off and pass through the screen (52) into the carbon collection bin (51).

3. The fluidized bed membrane reactor for methane cracking to hydrogen production as described in claim 1, characterized in that, The carbon collection mechanism (5) also includes a screen (52), which is located between the material discharge port and the carbon collection bin (51); The aperture of the screen (52) is larger than the diameter of the carbon-carrying medium (3). As the screen (52) vibrates, the carbon-carrying medium (3) with carbon products adsorbed on its surface passes through the screen (52) and falls into the carbon collection bin (51).

4. The fluidized bed membrane reactor for methane cracking to hydrogen production as described in claim 3, characterized in that, The methane cracking hydrogen production fluidized bed membrane reactor also includes a medium feed section located at the top of the lower shell (12). The medium feed section includes a feed bin and a feed pipe. The feed bin is connected to the lower shell (12) through the feed pipe.

5. The fluidized bed membrane reactor for methane cracking to hydrogen production as described in claim 2 or 3, characterized in that, The methane cracking hydrogen production fluidized bed membrane reactor also includes a vibration motor (42), which is located on the outer side wall of the middle part of the lower shell (12) to make the side wall of the lower shell (12) vibrate.

6. A method for producing hydrogen from methane through cracking, based on a fluidized bed membrane reactor for producing hydrogen from methane through cracking as described in any one of claims 1-5, characterized in that, The methane cracking method for hydrogen production includes the following steps: S1. Methane is introduced into the lower shell (12) filled with carbon-carrying medium (3) and with sufficient reaction temperature to carry out the cracking reaction; S2. Apply a vacuum to the inner cavity of the upper shell (11) using a vacuum pumping device to allow the hydrogen gas generated in the reaction to permeate and separate. S3. The heat from the combustion of the reaction tail gas is introduced into the lower shell (12) to heat the lower shell (12); S4. Intermittently remove carbon products and replenish carbon-carrying media (3).

7. The method for producing hydrogen from methane through cracking as described in claim 6, characterized in that, Step S1 also includes the following steps: S101. Adjust the methane feed flow rate and / or the vibration frequency of the reactor shell (1) to control the movement speed of the carbon-carrying medium (3) in the reactor.

8. The method for producing hydrogen from methane through cracking as described in claim 6, characterized in that, In step S1, the reaction temperature is 700℃-1000℃; the feed volume hourly space velocity of methane is 1000 / h-50000 / h.

9. The method for producing hydrogen from methane through cracking as described in claim 8, characterized in that, In step S2, the vacuum degree of the inner cavity of the upper shell (11) is 0.001 MPa-0.01 MPa.

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