Zero-carbon hydrogen production device and method based on pyrolysis of liquefied natural gas

Abstract

The invention relates to the technical field of zero-carbon hydrogen production, in particular to a zero-carbon hydrogen production device and method based on liquefied natural gas pyrolysis. The zero-carbon hydrogen production device comprises a pyrolytic reaction mechanism which is used for performing pyrolytic reaction on liquefied natural gas introduced into the pyrolytic reaction mechanism to generate hydrogen and fixed carbon under the action of a catalyst; the gas separation mechanism is used for purifying hydrogen generated by the pyrolytic reaction of the pyrolytic reaction mechanism to obtain a hydrogen product; a trapping mechanism for trapping solid carbon deposited on the catalyst filled in the pyrolytic reaction mechanism; and the waste heat recovery mechanism is used for recovering waste heat generated by the pyrolytic reaction in the pyrolytic reaction mechanism and preheating the liquefied natural gas entering the pyrolytic reaction mechanism. The device provided by the invention can avoid the influence on the activity of the catalyst and the inactivation of the active agent, thereby enhancing the catalytic efficiency; and waste heat generated by pyrolysis is recycled, so that energy conservation and environmental protection are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of zero-carbon hydrogen production, in particular to a zero-carbon hydrogen production device and method based on liquefied natural gas pyrolysis. BACKGROUND

[0002] As a clean energy, hydrogen is gradually becoming an important part of energy transformation. In recent years, with the promotion of global energy transformation, the demand for hydrogen as a clean energy is increasing, especially in the fields of transportation, industry, etc.

[0003] In the production of hydrogen, traditional hydrogen production methods mainly include coal gasification, water electrolysis and natural gas reforming, etc. Among them, natural gas reforming is the most widely used method for hydrogen production. By reacting methane in natural gas with water vapor at high temperature, hydrogen and carbon dioxide are generated. However, although natural gas reforming is widely used for hydrogen production, the emission of carbon dioxide has become a bottleneck restricting the technology of natural gas reforming for hydrogen production.

[0004] Liquefied natural gas pyrolysis technology is a new type of hydrogen production technology developed in recent years. Its basic principle is to heat liquefied natural gas to high temperature to promote pyrolysis reaction, thereby generating hydrogen and solid carbon, thereby avoiding the pollution of gaseous carbon dioxide to the environment. However, there are still some problems in liquefied natural gas pyrolysis for hydrogen production. Although liquefied natural gas pyrolysis technology can avoid the pollution of gaseous carbon dioxide to the environment, the treatment and utilization of solid carbon is still an important problem. At the same time, in the process of liquefied natural gas pyrolysis for hydrogen production, a suitable catalyst needs to be added to improve the reaction efficiency. The untreated solid carbon is deposited on the catalyst, which makes the catalyst easily deactivated at high temperature, resulting in reduced reaction efficiency. SUMMARY

[0005] In order to solve the technical problem in the background art that the treatment and utilization of solid carbon in the process of liquefied natural gas pyrolysis for hydrogen production is still an important problem, the untreated solid carbon is deposited on the catalyst, and the pyrolysis temperature is high, which makes the catalyst easily deactivated at high temperature, resulting in reduced reaction efficiency, the present application provides a zero-carbon hydrogen production device and method based on liquefied natural gas pyrolysis.

[0006] The present application sets up pyrolysis reaction mechanism, gas separation mechanism, capture mechanism and waste heat recovery mechanism. The gas separation mechanism separates and collects hydrogen and solid carbon. The capture mechanism captures the solid carbon deposited on the catalyst regularly, avoids affecting the activity of the catalyst, causes the deactivation of the active agent, and improves the catalytic efficiency. In pyrolysis, the waste heat recovery mechanism recycles the waste heat generated by pyrolysis, which is energy-saving and environmentally friendly.

[0007] In order to achieve the above object, the technical scheme adopted by the present application is as follows:

[0008] A zero-carbon hydrogen production device based on liquefied natural gas pyrolysis, comprising:

[0009] A pyrolysis reaction mechanism for pyrolysis of liquefied natural gas entering the pyrolysis reaction mechanism to generate hydrogen and fixed carbon under the action of a catalyst;

[0010] A gas separation mechanism connected to the pyrolysis reaction mechanism for separating and collecting hydrogen and fixed carbon generated by the pyrolysis reaction mechanism and purifying hydrogen to obtain high-purity hydrogen;

[0011] A trapping mechanism connected to the pyrolysis reaction mechanism for trapping solid carbon deposited on the catalyst filled in the pyrolysis reaction mechanism;

[0012] And a waste heat recovery mechanism connected to the pyrolysis reaction mechanism for recovering waste heat generated by the pyrolysis reaction in the pyrolysis reaction mechanism and preheating liquefied natural gas entering the pyrolysis reaction mechanism.

[0013] Further limited, the pyrolysis reaction mechanism includes a pyrolysis furnace and a gas inlet pipe communicating with the pyrolysis furnace, and a fluidized bed layer is further installed inside the pyrolysis furnace, and a plurality of separation membranes are arranged in the fluidized bed layer from top to bottom, and solid particles are filled between adjacent two separation membranes; the solid particles are catalysts; the pyrolysis furnace is connected with the gas separation mechanism, the trapping mechanism and the waste heat recovery mechanism.

[0014] Further limited, the gas separation mechanism includes a cyclone separator and a support plate arranged in the pyrolysis furnace from top to bottom; the support plate is connected with the inner wall of the pyrolysis furnace; the top of the cyclone separator is communicated with a gas outlet pipe, and the gas outlet pipe extends to the outside of the pyrolysis furnace; the lower surface of the support plate is provided with a feed pipe communicated with the inside of the cyclone separator, and the lower surface of the support plate is provided with a collection pipe communicated with the lower end of the cyclone separator, and the end of the collection pipe away from the cyclone separator is provided with a carbon discharge pipe; the carbon discharge pipe extends to the outside of the pyrolysis furnace.

[0015] Further limited, the gas separation mechanism further includes a conical cap, a disc-shaped pipe and a condensation bin; the conical cap is arranged on the top of the pyrolysis furnace, the disc-shaped pipe and the condensation bin are located outside the pyrolysis furnace, and the gas outlet pipe is communicated with the disc-shaped pipe in sequence after passing through the conical cap; the disc-shaped pipe is located in the condensation bin.

[0016] Further limited, the trapping mechanism includes a gas source pipe, a gas flow distributor, a circulation pipe, a filter pipe and a heating pipe; the gas flow distributor is located below the fluidized bed layer in the pyrolysis furnace; the gas source pipe, the circulation pipe, the filter pipe and the heating pipe are located outside the pyrolysis furnace, and the circulation pipe is located above the fluidized bed layer; the output end of the gas source pipe is communicated with the input end of the gas source pipe through the gas flow distributor, the circulation pipe, the filter pipe and the heating pipe.

[0017] Further limited, the trapping mechanism further includes a heater and a circulating fan located outside the pyrolysis furnace respectively; the two ends of the heater are communicated with different position points on the heating pipe respectively; the circulating fan is communicated with the input end of the gas source pipe.

[0018] Further limited, the recovery mechanism includes a heat exchanger installed in the pyrolysis furnace, and a waste heat recovery furnace is arranged outside the pyrolysis furnace and is in thermal connection with the heat exchanger through a heat exchange pipe.

[0019] A zero-carbon hydrogen production method formed by using the zero-carbon hydrogen production device based on liquefied natural gas pyrolysis, comprising the following steps:

[0020] S1, the liquefied natural gas is preheated and gasified and then introduced into the pyrolysis reaction mechanism, and under the action of the catalyst, the preheated and gasified liquefied natural gas is pyrolyzed at 700-1000 DEG C to generate hydrogen and solid carbon;

[0021] S2, the hydrogen and the solid carbon enter the gas separation mechanism for separation, the solid carbon is discharged from the pyrolysis reaction mechanism for collection, and the hydrogen is purified to obtain a hydrogen product; meanwhile, the waste heat generated by the pyrolysis reaction is recovered by the recovery mechanism and used for preheating and gasifying the liquefied natural gas;

[0022] S3, the solid carbon deposited on the catalyst in the pyrolysis reaction mechanism is also trapped by the trapping mechanism.

[0023] Further limited, the specific process of the step S3 is: stopping the liquefied natural gas from entering, introducing inert gas into the pyrolysis reaction mechanism through the trapping mechanism, and trapping the solid carbon deposited on the catalyst by using the inert gas.

[0024] Further limited, the flow rate of the inert gas is 0.5-2 m / s, and the temperature of the inert gas is 500-850 DEG C; the inert gas is a mixed gas formed by nitrogen and hydrogen.

[0025] Compared with the prior art, the beneficial effects of the present application are:

[0026] 1. The pyrolysis reaction mechanism, gas separation mechanism, trapping mechanism and waste heat recovery mechanism are set, the gas separation mechanism separates and collects hydrogen and solid carbon, the solid carbon deposited on the catalyst is trapped regularly through the trapping mechanism, the activity of the catalyst is avoided from being affected, the deactivation of the active agent is avoided, the catalytic efficiency is improved, the waste heat generated in the pyrolysis is recycled through the waste heat recovery mechanism in the pyrolysis, and energy saving and environmental protection are achieved.

[0027] 2. The metal film and the transition metal catalyst are designed, the metal film can effectively avoid direct deposition and blockage of particles, thereby reducing the formation of carbon deposition and the accumulation of particles in the fluidized bed, maintaining the activity of the catalyst, prolonging the service life of the catalyst, and the smooth spherical shape of the catalyst surface can reduce the opportunity of impurities and deposits adhering, especially in the case of strong gas flow, which helps to improve the pyrolysis efficiency and ensure smooth gas flow, enhance the reaction rate, and improve the overall efficiency of the system.

[0028] 3. In the application, hydrogen is discharged from the upper end of the cyclone separator and concentrated into the disc-shaped pipe in the conical cap, the specific disc-shaped pipe can prolong the flow time of hydrogen and make it sufficient to be cooled, the hydrogen flowing through the condensing bin is condensed to reduce the temperature to normal temperature, thereby improving the purity of hydrogen.

[0029] 4. In the pyrolysis process, no carbon dioxide emissions are generated, which meets the global emission reduction target, helps to reduce the impact of greenhouse gases on climate change, and the waste heat in the pyrolysis process is recycled through the heat exchanger, which can effectively preheat the natural gas entering the reactor, improve the reaction efficiency, and reduce energy consumption.

[0030] 5. The application sets up a trapping mechanism to trap residual solid carbon and regenerate the catalyst, in the adjustment process, the heated inert gas is filled into the gas distributor through the gas source pipe, so that it flows through the reactor at a suitable flow rate, the deposits on the surface of the catalyst are carried away by the gas flow, and the solid carbon is filtered through the filter pipe and collected at the bottom of the filter pipe, and the unreacted inert gas is circulated to the pyrolysis furnace through the heating pipe to wash the catalyst, thereby avoiding the release of carbon, reducing environmental pollution, maintaining the activity and reaction efficiency of the catalyst, prolonging the service life of the catalyst, and reducing operating costs. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A schematic diagram of a zero-carbon hydrogen production device based on liquefied natural gas pyrolysis is provided for the application;

[0032] Figure 2 A perspective view of the pyrolysis furnace structure of the application;

[0033] Figure 3 A perspective view of a fluidized bed layer structure according to the present application;

[0034] Figure 4 A perspective view of a separation membrane structure according to the present application;

[0035] Figure 5 A perspective view of a carbon discharge pipe structure according to the present application;

[0036] Figure 6 A perspective view of a cyclone separator structure according to the present application;

[0037] Figure 7 A perspective view of a disc-shaped pipe structure according to the present application;

[0038] Figure 8 A first perspective view of a heater structure according to the present application;

[0039] Figure 9 A second perspective view of a heater structure according to the present application;

[0040] Figure 10 A perspective view of a waste heat recovery furnace structure according to the present application;

[0041] In the drawings:

[0042] 1, pyrolysis reaction mechanism; 11, pyrolysis furnace; 12, gas inlet pipe; 13, fluidized bed layer; 14, separation membrane; 15, solid particles; 2, gas separation mechanism; 21, support plate; 22, cyclone separator; 23, feed pipe; 24, gas outlet pipe; 25, collection pipe; 26, carbon discharge pipe; 27, conical cap; 28, disc-shaped pipe; 29, condensation bin; 3, trapping mechanism; 31, air flow distributor; 32, circulation pipe; 33, filter pipe; 34, heating pipe; 35, heater; 36, circulation fan; 37, gas source pipe; 4, recovery mechanism; 41, heat exchanger; 42, waste heat recovery furnace. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application.

[0044] Referring to Figures 1-10 In an embodiment of the present application, a zero-carbon hydrogen production device based on liquefied natural gas pyrolysis includes:

[0045] The pyrolysis reaction mechanism 1 is used for pyrolysis reaction of liquefied natural gas entering the pyrolysis reaction mechanism 1 to generate hydrogen and fixed carbon under the action of a catalyst;

[0046] Gas separation mechanism 2 is connected to pyrolysis reaction mechanism 1 and is used to separate and collect hydrogen and fixed carbon generated by pyrolysis reaction of pyrolysis reaction mechanism 1, and to purify hydrogen to obtain high-purity hydrogen.

[0047] The collection mechanism 3 is connected to the pyrolysis reaction mechanism 1 and is used to collect and collect the solid carbon deposited in the pyrolysis reaction mechanism 1 during the pyrolysis reaction.

[0048] Waste heat recovery unit 4 is connected to pyrolysis reaction unit 1 and is used to recover the waste heat generated by the pyrolysis reaction in pyrolysis reaction unit 1 and to preheat the liquefied natural gas entering pyrolysis reaction unit 1.

[0049] See Figure 1 , Figure 2 , Figure 3 and Figure 4 In another embodiment of the present invention, the pyrolysis reaction mechanism 1 includes a pyrolysis furnace 11 and an inlet pipe 12 communicating with the pyrolysis furnace 11. A fluidized bed 13 is also installed inside the pyrolysis furnace 11. A separation membrane 14 is fixedly connected to the inner surface of the fluidized bed 13. The separation membrane 14 consists of multiple layers arranged vertically, with solid particles 15 filling the space between each adjacent layer of separation membrane 14; the solid particles 15 are the catalyst. The pyrolysis furnace 11 is connected to a gas separation mechanism 2, a collection mechanism 3, and a waste heat recovery mechanism 4, respectively.

[0050] During implementation, preheated and vaporized liquefied natural gas is introduced into the bottom of the pyrolysis furnace 11 through the inlet pipe 12. Inside the pyrolysis furnace 11, the preheated and vaporized liquefied natural gas comes into contact with high-temperature solid particles 15. Under the strong flow of the preheated and vaporized liquefied natural gas, the solid particles 15 will be suspended, which will accelerate the heat transfer and reaction rate. At the high temperature required for the reaction, the vaporized liquefied natural gas undergoes high-temperature pyrolysis to produce solid carbon and hydrogen. The hydrogen produced is then filtered through the separation membrane 14 to prevent impurities from being discharged with the hydrogen.

[0051] Preferably, the separation membrane 14 is made of metal, and the solid particles 15, i.e., the catalyst, are spherical catalysts with smooth surfaces. The metal membrane is used for gas separation, efficiently permeating hydrogen. It has good thermal conductivity, which helps to evenly distribute heat and prevent local overheating. This can enhance the reaction rate and improve system efficiency. In addition, the metal membrane can effectively isolate the solid particles 15 from the gas flow, ensuring smooth gas flow and effectively avoiding direct particle deposition and blockage, thereby reducing the formation of carbon deposits and particle accumulation in the fluidized bed, maintaining catalyst activity, and extending catalyst life. The spherical shape of the solid particles 15 has a large surface area, which helps to improve the reaction rate. At the same time, the smooth surface of the spherical particles can reduce the chance of impurities and deposits adhering, especially under strong gas flow conditions. By setting up the metal membrane and spherical catalyst, the pyrolysis efficiency can be improved, the smooth gas flow can be ensured, the reaction rate can be enhanced, and the overall system efficiency can be improved.

[0052] Preferably, the catalyst is a transition metal compound. Exemplary examples include NiO, Fe2O3, Co3O4, MoS2, WS2, WC, or MoC. To prevent residual solid carbon from accumulating on the catalyst surface and to improve the catalyst's activity, selectivity, and stability, the surface of the solid particles 15 is modified with a noble metal. Noble metals not only promote carbon oxidation and elimination but also help the catalyst maintain high catalytic activity under high-temperature conditions. The noble metals are Pt, Pd, Au, or Rh. Noble metal modification enhances the catalyst's resistance to carbon deposition. In practice, the method of noble metal modification of the catalyst and the amount of noble metal incorporated are existing known technologies.

[0053] See Figure 1 , Figure 5 , Figure 6 and Figure 7 In one embodiment of the present invention, the gas separation mechanism 2 includes a cyclone separator 22 and a support plate 21 arranged from top to bottom inside the pyrolysis furnace 11; the support plate 21 is connected to the inner wall of the pyrolysis furnace 11; the top of the cyclone separator 22 is connected to an outlet pipe 24, which extends to the outside of the pyrolysis furnace 11; a feed pipe 23 communicating with the inside of the cyclone separator 22 is provided on the lower surface of the support plate 21, and a collection pipe 25 communicating with the lower end of the cyclone separator 22 is installed on the lower surface of the support plate 21; a carbon discharge pipe 26 is provided at one end of the collection pipe 25 away from the cyclone separator 22; the carbon discharge pipe 26 extends to the outside of the pyrolysis furnace 11.

[0054] In the pyrolysis reactor, solid carbon is usually discharged together with hydrogen. In order to separate hydrogen from solid carbon, the gas separation mechanism 2 includes a support plate 21 installed inside the pyrolysis furnace 11. A cyclone separator 22 is fixedly connected to the upper surface of the support plate 21 by a bracket. The input end of the cyclone separator 22 is fixedly connected to a feed pipe 23 extending to the lower surface of the support plate 21. The outlet end of the cyclone separator 22 is fixedly connected to an outlet pipe 24. The settling end of the cyclone separator 22 is fixedly connected to a collection pipe 25 through a connecting pipe extending to the lower surface of the support plate 21. The lower surface of the collection pipe 25 is fixedly connected to a carbon discharge pipe 26 with a solenoid valve. After pyrolysis, the gas passes through the feed pipe 23 and the cyclone separator 22, which can separate solid carbon from the gas flow. The gas flow separation relies on the inertial principle of the high-speed gas flow to separate the heavier solid carbon particles from the gas and let them settle into the collection pipe 25 for collection. At this time, the solid carbon can be periodically discharged or periodically collected through the carbon discharge pipe 26.

[0055] In this embodiment, the gas separation mechanism 2 further includes a conical cap 27, a disc tube 28, and a condensation chamber 29; the conical cap 27 is disposed on the top of the pyrolysis furnace 11, the disc tube 28 and the condensation chamber 29 are located outside the pyrolysis furnace 11, and the gas outlet pipe 24 passes through the conical cap 27 and is connected to the disc tube 28 in sequence; the disc tube 28 is located inside the condensation chamber 29.

[0056] To ensure the purity of hydrogen meets usage requirements, a conical cap 27 is fixedly connected to the upper surface of the pyrolysis furnace 11. A disc-shaped tube 28 with a valve is fixedly connected to the upper surface of the conical cap 27. A condensation chamber 29 is fixedly connected to the outer surface of the disc-shaped tube 28. After separation, the hydrogen gas will be discharged from the upper outlet pipe 24 of the cyclone separator 22 and concentrated in the conical cap 27 before being discharged into the disc-shaped tube 28. The specially designed disc-shaped tube 28 can extend the flow time of the hydrogen gas, allowing it to be cooled sufficiently. The condensation chamber 29 condenses the flowing hydrogen gas, lowering its temperature to room temperature, thereby improving the purity of the hydrogen gas. After cooling, the hydrogen gas is discharged from the disc-shaped tube 28 and collected in a hydrogen collection tank.

[0057] See Figure 1 , Figure 8 and Figure 9 In one embodiment of the present invention, the collection mechanism 3 includes a gas source pipe 37, an airflow distributor 31, a circulation pipe 32, a filter pipe 33, and a heating pipe 34; the airflow distributor 31 is located below the fluidized bed 13 inside the pyrolysis furnace 11; the gas source pipe 37, the circulation pipe 32, the filter pipe 33, and the heating pipe 34 are located outside the pyrolysis furnace 11, and the circulation pipe 32 is located above the fluidized bed 13; the output end of the gas source pipe is connected to the input end of the gas source pipe after passing through the airflow distributor 31, the circulation pipe 32, the filter pipe 33, and the heating pipe 34.

[0058] In this embodiment, the collection mechanism 3 also includes a heater 35 and a circulating fan 36 located outside the pyrolysis furnace 11 respectively; the two ends of the heater 35 are respectively connected to different points on the heating pipe 34; the circulating fan 36 is connected to the input end of the gas source pipe 37.

[0059] Preferably, the airflow distributor 31 is installed below the fluidized bed 13, and the upper end of the pyrolysis furnace 11 is fixedly connected to the circulation pipe 32. The heater 35 is arranged on one side of the heating pipe 34, and the heater 35 is connected in series with the heating pipe 34 through a branch pipe.

[0060] During the reaction, the catalyst accumulates solid carbon deposits, necessitating periodic regeneration to remove these deposits and restore its catalytic activity. In this process, the feed pipe 23 is closed to stop the inflow of liquefied natural gas. Driven by the circulating fan 36, heated inert gas is introduced into the gas distributor 31 through the gas source pipe 37. This gas flows upwards through the fluidized bed 13 at a suitable velocity, rinsing the surface of the solid particles 15 (catalyst). The increased temperature and airflow physically remove the deposits (solid carbon) from the catalyst surface, effectively trapping the solid carbon. The gas distributor 31 ensures uniform distribution of the inert gas, maintaining both uniform and efficient gas flow. To enhance the removal of deposits, a circulation pipe 32, a filter pipe 33, and a heating pipe 34 can be used to circulate the inert gas after rinsing. When the deposits (solid carbon) on the catalyst surface inside the pyrolysis furnace 11 are carried away by the inert gas flow, they enter the filter pipe 33 through the circulation pipe 32 to filter the inert gas flow containing solid carbon. The solid carbon is trapped and collected at the bottom of the filter pipe 33, reducing the re-attachment of deposits. The unfiltered inert gas is then reheated through the heating pipe 34 and re-enters the pyrolysis furnace 11 through the gas source pipe 37 to continuously rinse the catalyst, thereby avoiding carbon release, reducing environmental pollution, maintaining catalyst activity and reaction efficiency, extending catalyst lifespan, and reducing operating costs. The inert gas physically removes deposits through temperature increase and airflow scouring.

[0061] To ensure the temperature of the inert gas remains stable during the circulating flushing process, the circulating fan 36 draws inert gas from the pyrolysis furnace 11. The inert gas is heated as it flows through the heating pipe 34. At the same time, the temperature of the circulating inert gas is controlled by the heater 35, so that the inert gas that meets the set temperature is circulated to the gas source pipe 37 for reuse.

[0062] See Figure 1 and Figure 10In one embodiment of the present invention, the recovery mechanism 4 includes a heat exchanger 41 installed inside the pyrolysis furnace 11, and a waste heat recovery furnace 42 is provided outside the pyrolysis furnace 11. The waste heat recovery furnace 42 is thermally connected to the heat exchanger 41 through heat exchange pipes. The waste gas generated during the pyrolysis process is typically at a high temperature, and a portion of its heat energy can be recovered through the heat exchanger 41 and transferred to the waste heat recovery furnace 42 for preheating the liquefied natural gas entering the reactor. The pyrolysis process does not generate carbon dioxide emissions, complying with global emission reduction targets and helping to reduce the impact of greenhouse gases on climate change. Furthermore, the heat from the waste gas during the pyrolysis process is recovered through the heat exchanger 41, effectively preheating the natural gas entering the reactor, improving reaction efficiency, and reducing energy consumption.

[0063] Example 2

[0064] A zero-carbon hydrogen production method using the zero-carbon hydrogen production device based on liquefied natural gas pyrolysis as described in Example 1.

[0065] The zero-carbon hydrogen production method provided in this embodiment includes the following steps:

[0066] S1. After being preheated and vaporized, liquefied natural gas is fed into pyrolysis reaction unit 1. Under the action of a catalyst, the preheated and vaporized liquefied natural gas undergoes pyrolysis at 700-1000℃ to produce hydrogen and solid carbon.

[0067] The pyrolysis reaction is as follows:

[0068] CH4→C+2H2

[0069] In this context, CH4 represents methane, C represents solid carbon, and H2 represents hydrogen.

[0070] Specifically, after being gasified, liquefied natural gas is introduced into the bottom of the pyrolysis furnace 11 through the gas inlet pipe 12. The natural gas comes into contact with solid particles 15 in the pyrolysis furnace 11. Under the strong flow of gas, these solid particles 15 will be suspended, which will accelerate the heat transfer and reaction rate, so that the liquefied natural gas reaches the high temperature required for the reaction and produces solid carbon and hydrogen through pyrolysis.

[0071] S2, hydrogen and solid carbon enter the gas separation unit 2 for separation. The solid carbon is discharged and collected in the pyrolysis reaction unit 1, while the hydrogen is purified to obtain hydrogen product. Simultaneously, the waste heat generated by the pyrolysis reaction is recovered using the recovery unit 4 and used to preheat and vaporize the liquefied natural gas. The waste heat generated during the pyrolysis process is recovered using the recovery unit 4 and used to preheat the liquefied natural gas entering the pyrolysis reaction unit 1, achieving waste heat recovery and reuse, thus achieving energy conservation.

[0072] Specifically, solid carbon and hydrogen are discharged from the pyrolysis furnace 11 together through the separation membrane 14, and then separated by the separation mechanism 2. Solid carbon and hydrogen enter the cyclone separator 22 together through the feed pipe 23. After cyclone separation, the solid carbon is separated from the hydrogen flow and settles into the collection pipe 25 for collection. At this time, the solid carbon is periodically discharged from the pyrolysis furnace 11 for collection through the carbon discharge pipe 26. The separated hydrogen is discharged from the upper outlet pipe 24 of the cyclone separator 22 and concentrated in the conical cap 27 and discharged into the disc tube 28. The disc tube 28 extends the flow time of the hydrogen so that it can be cooled sufficiently. The flowing hydrogen is condensed through the condensation chamber 29 to reduce its temperature to room temperature, thereby improving the purity of the hydrogen and obtaining hydrogen product. The waste gas generated in the pyrolysis reaction is usually at a high temperature. The heat in the pyrolysis furnace 11 is recovered to the waste heat recovery furnace 42 through the heat exchanger 41 and heat exchange tube. The recovered heat energy is used to preheat the liquefied natural gas entering the pyrolysis furnace 11.

[0073] S3. The solid carbon deposited on the catalyst in the pyrolysis reaction unit 1 is also captured by the trapping mechanism 3.

[0074] The specific process of step S3 is as follows: The intake of liquefied natural gas is stopped, and inert gas is introduced into the pyrolysis reaction unit 1 through the collection mechanism 3. The inert gas is used to collect the solid carbon deposited on the catalyst. The inert gas is a mixture of nitrogen and hydrogen. Specifically, inert gas at a temperature of 500-850℃ is introduced into the pyrolysis reaction unit 1 at a flow rate of 0.5-2 m / s. The inert gas carries away the solid carbon deposited on the catalyst, simultaneously regenerating the catalyst. The solid carbon is then collected after filtration through the collection mechanism 3. The filtered inert gas is then reheated and recirculated into the pyrolysis reaction unit 1. Using inert gas at 500-850℃ causes the solid carbon on the catalyst surface to expand due to heat. This weakens the adhesion of the solid carbon to the catalyst surface, making it easier to wash off. Simultaneously, the high-temperature inert gas regenerates the catalyst, preventing deactivation at high temperatures, thus stabilizing the catalyst's activity and improving the efficiency of the pyrolysis reaction.

[0075] During implementation, after a period of use, the pyrolysis furnace 11 needs to have the deposits on the catalyst surface in the fluidized bed 13 removed to restore its catalytic activity. Therefore, the supply of natural gas to the pyrolysis furnace 11 is stopped, i.e., the inlet pipe 12 and feed pipe 23 are closed. Inert gas heated to 500-850℃ is introduced through the gas source pipe 37 and evenly distributed to the bottom of the fluidized bed 13 by the airflow distributor 31, allowing it to pass through the reactor at a suitable flow rate to wash the catalyst surface. The high-temperature inert gas penetrates the fluidized bed 13 from bottom to top, suspending and strongly flowing the solid particles 15. When the inert gas passes through the fluidized bed, the gas velocity and temperature work synergistically. The process involves using high temperature to soften the carbon layer on the catalyst surface, and using airflow shear force to scour and peel off the solid carbon deposits adhering to the catalyst surface, reducing the re-adhesion of deposits. After the deposits on the catalyst surface are carried away by the airflow, the inert gas carrying the solid carbon enters the filter pipe 33 through the circulation pipe 32. The filter pipe 33 traps solid carbon particles and accumulates at its bottom. The purified inert gas enters the heating pipe 34, and the heater 35 supplements the heating pipe 34 with heat through the branch pipe, maintaining the gas temperature at 500℃~850℃. The circulating fan 36 pressurizes the heated inert gas and sends it back to the gas source pipe 37, forming a closed loop to achieve the circulating flushing of the catalyst.

[0076] Preferably, the solid carbon on the catalyst is scoured and captured by an inert gas at 500-850℃ in two stages. The first stage involves introducing an inert gas at 800-850℃ at a flow rate of 0.5-2 m / s for 10-15 minutes. The second stage involves introducing a gas at 500-700℃ at a flow rate of 0.5-2 m / s for 30-90 minutes. Preferably, the inert gas is a mixture of nitrogen (90-95 wt%) and hydrogen (5-10 wt%), in which hydrogen atoms penetrate into the interstitial spaces of the catalyst lattice, repairing high-temperature defects. This gradient cooling, combined with the hydrogen mixture repair process, solves the deactivation problems caused by carbon buildup and sintering.

[0077] During this process, high-temperature waste gas is also generated. The heat in the pyrolysis furnace 11 is recovered to the waste heat recovery furnace 42 through the heat exchanger 41 and heat exchange tube, and the recovered heat energy is used to preheat the liquefied natural gas entering the pyrolysis furnace 11.

[0078] It should be noted that in the above embodiments, the high-temperature heat required by the pyrolysis reaction mechanism 1 is provided by external low-carbon / zero-carbon energy. Low-carbon / zero-carbon energy includes electricity generated by renewable energy or nuclear energy, which directly provides heat to the pyrolysis reaction mechanism 1 through resistance heating or electromagnetic induction heating. Renewable energy includes solar photovoltaic and wind energy.

[0079] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A zero-carbon hydrogen production device based on liquefied natural gas pyrolysis, characterized in that, include: The pyrolysis reaction mechanism (1) is used to pyrolyze the liquefied natural gas introduced into the pyrolysis reaction mechanism (1) under the action of a catalyst to generate hydrogen and fix carbon. The gas separation mechanism (2) is connected to the pyrolysis reaction mechanism (1) and is used to separate and collect the hydrogen and fixed carbon generated by the pyrolysis reaction of the pyrolysis reaction mechanism (1) and to purify the hydrogen to obtain high-purity hydrogen. The trapping mechanism (3) is connected to the pyrolysis reaction mechanism (1) and is used to trap solid carbon deposited on the catalyst filled in the pyrolysis reaction mechanism (1); The waste heat recovery unit (4) is connected to the pyrolysis reaction unit (1) to recover the waste heat generated by the pyrolysis reaction in the pyrolysis reaction unit (1) and to preheat the liquefied natural gas entering the pyrolysis reaction unit (1).

2. The zero-carbon hydrogen production device based on liquefied natural gas pyrolysis according to claim 1, characterized in that, The pyrolysis reaction mechanism (1) includes a pyrolysis furnace (11) and an inlet pipe (12) connected to the pyrolysis furnace (11). The pyrolysis furnace (11) is also equipped with a fluidized bed (13). Multiple separation membranes (14) are arranged in the fluidized bed (13) from top to bottom. Solid particles (15) are filled between two adjacent separation membranes (14). The solid particles (15) are catalysts. The pyrolysis furnace (11) is connected to a gas separation mechanism (2), a collection mechanism (3), and a waste heat recovery mechanism (4).

3. The zero-carbon hydrogen production device based on liquefied natural gas pyrolysis according to claim 2, characterized in that, The gas separation mechanism (2) includes a cyclone separator (22) and a support plate (21) arranged from top to bottom inside the pyrolysis furnace (11); the support plate (21) is connected to the inner wall of the pyrolysis furnace (11); the top of the cyclone separator (22) is connected to an outlet pipe (24), which extends to the outside of the pyrolysis furnace (11); the lower surface of the support plate (21) is provided with a feed pipe (23) that communicates with the inside of the cyclone separator (22); a collection pipe (25) that communicates with the lower end of the cyclone separator (22) is installed on the lower surface of the support plate (21); a carbon discharge pipe (26) is provided at one end of the collection pipe (25) away from the cyclone separator (22); the carbon discharge pipe (26) extends to the outside of the pyrolysis furnace (11).

4. The zero-carbon hydrogen production device based on liquefied natural gas pyrolysis according to claim 3, characterized in that, The gas separation mechanism (2) further includes a conical cap (27), a disc tube (28), and a condensation chamber (29); the conical cap (27) is set on the top of the pyrolysis furnace (11), the disc tube (28) and the condensation chamber (29) are located outside the pyrolysis furnace (11), and the gas outlet pipe (24) passes through the conical cap (27) and is connected to the disc tube (28) in sequence; the disc tube (28) is located inside the condensation chamber (29).

5. The zero-carbon hydrogen production device based on liquefied natural gas pyrolysis according to claim 4, characterized in that, The collection mechanism (3) includes a gas source pipe (37), an airflow distributor (31), a circulation pipe (32), a filter pipe (33), and a heating pipe (34); the airflow distributor (31) is located below the fluidized bed (13) inside the pyrolysis furnace (11); the gas source pipe (37), the circulation pipe (32), the filter pipe (33), and the heating pipe (34) are located outside the pyrolysis furnace (11), and the circulation pipe (32) is located above the fluidized bed (13); the output end of the gas source pipe (37) is connected to the input end of the gas source pipe (37) after passing through the airflow distributor (31), the circulation pipe (32), the filter pipe (33), and the heating pipe (34).

6. The zero-carbon hydrogen production device based on liquefied natural gas pyrolysis according to claim 5, characterized in that, The collection mechanism (3) also includes a heater (35) and a circulating fan (36) located outside the pyrolysis furnace (11); the two ends of the heater (35) are connected to different points on the heating pipe (34); the circulating fan (36) is connected to the input end of the gas source pipe (37).

7. The zero-carbon hydrogen production device based on liquefied natural gas pyrolysis according to claim 2, characterized in that, The recycling mechanism (4) includes a heat exchanger (41) installed inside the pyrolysis furnace (11), and a waste heat recovery furnace (42) is provided outside the pyrolysis furnace (11), which is connected to the heat exchanger (41).

8. A zero-carbon hydrogen production method using the zero-carbon hydrogen production device based on liquefied natural gas pyrolysis as described in claim 6, characterized in that, Includes the following steps: S1. After preheating and gasification, liquefied natural gas is fed into the pyrolysis reaction mechanism (1). Under the action of the catalyst, the preheated and gasified liquefied natural gas undergoes pyrolysis at 700-1000℃ to generate hydrogen and solid carbon. S2, hydrogen and solid carbon enter the gas separation unit (2) for separation, solid carbon is discharged from the pyrolysis reaction unit (1) for collection, and hydrogen is purified to obtain hydrogen product; at the same time, the waste heat generated by the pyrolysis reaction is recovered by the recovery unit (4) and used for preheating and gasification of liquefied natural gas. S3. The solid carbon deposited on the catalyst in the pyrolysis reaction mechanism (1) is also captured by the trapping mechanism (3).

9. The zero-carbon hydrogen production method according to claim 8, characterized in that, The specific process of step S3 is as follows: stop the entry of liquefied natural gas, introduce inert gas into the pyrolysis reaction unit (1) through the collection mechanism (3), and use the inert gas to collect the solid carbon deposited on the catalyst.

10. The zero-carbon hydrogen production method according to claim 9, characterized in that, The inert gas has a flow rate of 0.5-2 m / s and a temperature of 500-850℃; the inert gas is a mixture of nitrogen and hydrogen.

Images