Bamboo-based hard carbon and co-production system and method of shaped particles

Abstract

The application discloses a bamboo-based hard carbon and shaped particle co-production system and method, which comprises a bamboo pretreatment unit, a heat treatment furnace, a transient Joule heat carbonization unit and a residual material treatment unit. The bamboo pretreatment unit separates the raw material main material into bamboo white blocks and bamboo-based residual materials. The heat treatment furnace is sequentially provided with an air pressure baking area, an air pressure pyrolysis area and a cooling area along a first direction. The air pressure baking area is used for dehydration and pre-carbonization treatment of the bamboo white blocks. The air pressure pyrolysis area is used for pyrolysis of the baked bamboo white blocks to obtain carbonized bamboo white blocks. The cooling area is used for cooling by cold air and converting the cold air into hot air. The transient Joule heat carbonization unit is connected with the cooling area. Bamboo-based hard carbon material is obtained by high-temperature and high-pressure through the Joule heat pressure technology. The residual material treatment unit is connected with the bamboo pretreatment unit, the air pressure pyrolysis area and the cooling area. The bamboo-based residual materials are crushed and dried by high-temperature pyrolysis gas and hot air. The shaped particles are obtained by high-pressure preparation. The whole chain preparation from the biomass raw material to the high-performance negative electrode material is realized. The whole component high-value utilization of the bamboo material is realized.

Description

Technical Field

[0001] This invention relates to the field of biomass high-value utilization and electrode material preparation technology, specifically to a system and method for the co-production of bamboo-based hard carbon and molded pellets. Background Technology

[0002] With the booming development of new energy vehicles and grid energy storage industries, the demand for high-performance secondary battery anode materials has increased significantly. Among them, hard carbon, due to its unique interlayer structure, excellent rate performance, and low-cost potential, has become the preferred anode material for next-generation sodium-ion batteries. However, the industrialization of hard carbon currently faces challenges such as limited precursor sources and high production costs, which directly restrict the cost competitiveness of sodium-ion batteries. In the process of continuous technological progress and the advancement of dual-carbon goals, finding green, renewable, and inexpensive biomass sources as hard carbon precursors has become an industry consensus. Bamboo, as a biomass resource with a short growth cycle, huge yield, and rich in cellulose and lignin, is considered an ideal raw material for preparing high-quality hard carbon.

[0003] However, the preparation of bamboo-based hard carbon faces multiple bottlenecks. On the raw material side, bamboo itself has a low thermal conductivity, and the physicochemical properties of different parts (bamboo white, bamboo nodes, and bamboo green) vary greatly, leading to existing preparation technologies consistently facing the dual challenges of poor product consistency and low resource utilization. Regarding system energy efficiency and integration, existing technologies also have significant limitations. The large amount of high-temperature volatiles (pyrolysis gas) generated during pyrolysis and the waste heat from the cooling stage are usually directly emitted, resulting in low system energy efficiency. Summary of the Invention

[0004] The main objective of this invention is to propose a system and method for the co-production of bamboo-based hard carbon and molded granules, aiming to solve the above-mentioned problems.

[0005] To achieve the above objectives, the present invention proposes a system for the co-production of bamboo-based hard carbon and molded pellets, comprising: The bamboo pretreatment unit is used to separate the main raw material into bamboo white blocks and bamboo base residue; A heat treatment furnace extends along a first direction and is provided with a pressure baking zone, a pressure pyrolysis zone, and a cooling zone in sequence along the first direction. The pressure baking zone is used to dehydrate and pre-carbonize the bamboo white blocks to obtain baked bamboo white blocks. The pressure pyrolysis zone is used to generate high-temperature pyrolysis gas to heat the baked bamboo white blocks to obtain carbonized bamboo white blocks. The cooling zone is used to cool the carbonized bamboo white blocks with cold air to obtain bamboo-based hard carbon sheet precursors and to convert the cold air into hot air. A transient Joule thermal carbonization unit, connected to the cooling zone, is used to obtain a bamboo-based hard carbon material with a closed-cell structure by high-temperature and high-pressure pressing of the bamboo-based hard carbon sheet precursor using Joule hot pressing technology; and... The residue processing unit is connected to the bamboo pretreatment unit, the pneumatic pyrolysis zone, and the cooling zone. It is used to crush the bamboo-based residue output from the bamboo pretreatment unit, and use the high-temperature pyrolysis gas input from the pneumatic pyrolysis zone and the hot air input from the cooling zone to dry the crushed bamboo-based residue. The dried bamboo-based residue is then subjected to high pressure to prepare shaped particles. The first direction is perpendicular to the up and down direction.

[0006] Optionally, the heat treatment furnace is provided with a running track, which extends along the first direction; The bamboo-based hard carbon and shaped granule co-production system also includes a pyrolysis reactor, which is slidably installed on the running track so that it can slide relative to the heat treatment furnace along the first direction. It is used to transport the bamboo white blocks through the pressure baking zone, the pressure pyrolysis zone and the cooling zone in sequence to obtain the bamboo-based hard carbon sheet precursor.

[0007] Optionally, the pyrolysis reactor includes: The outer protective vessel body has an opening at the top. A lid is fitted over the upper opening; The reaction assembly, housed within the outer protective vessel and connected to the vessel lid, includes a plurality of spaced-apart tubular reaction chambers. Each tubular reaction chamber comprises a tube body, a fixed heating column, and a plurality of rotating stirring shafts. The tube body is used to contain the bamboo white blocks, and the top wall of the tube body has an exhaust port. The fixed heating column and the plurality of rotating stirring shafts are located within the tube body, with the plurality of rotating stirring shafts positioned around the outer periphery of the fixed heating column. Each rotating stirring shaft is rotatable relative to the tube body around its axis. When the pyrolysis reactor moves to the gas pressure pyrolysis zone, the fixed heating column is in a heating state, and the rotating stirring shafts are in a rotating state to agitate the bamboo white blocks within the tube body; and... The pressure limiting assembly includes multiple pressure limiting valves, which are respectively located at the exhaust ports of multiple pipes. When the pressure inside the pipe is greater than a preset value, the pressure limiting valve is in the open state to allow the gas inside the pipe to be discharged.

[0008] Optionally, the pyrolysis reactor further includes multiple magnetic drive components. These components are disposed on the reactor lid and are driven and connected to the multiple rotating stirring shafts one by one. Each magnetic drive component includes an active magnetic rotor, a driven magnetic rotor, and a drive motor. The active magnetic rotor is disposed on the upper side of the reactor lid, and the driven magnetic rotor is disposed on the lower side of the reactor lid, corresponding to the active magnetic rotor, and is sleeved on the outside of the rotating stirring shaft. The drive motor is driven and connected to the active magnetic rotor to drive the active magnetic rotor to rotate the driven magnetic rotor, thereby causing the driven magnetic rotor to drive the rotating stirring shaft to rotate around its axis.

[0009] Optionally, a thermal expansion gap is provided between the bottom end of each tubular reaction chamber and the bottom wall of the outer protective vessel.

[0010] Optionally, the fixed heating column includes a resistance heating element and an insulating thermally conductive ceramic layer, wherein the insulating thermally conductive ceramic layer is wrapped around the resistance heating element.

[0011] Optionally, the transient Joule thermal carbonization unit includes: Vacuum enclosure; A pressure rod is inserted into the upper wall of the vacuum chamber and can move relative to the vacuum chamber in the vertical direction under force. An insulating base is disposed on the bottom wall of the vacuum chamber; A quartz tube is disposed on the insulating base and extends in the vertical direction, and is used to accommodate the bamboo-based hard carbon sheet precursor. A graphite electrode is inserted into the quartz tube along the vertical direction and pressed onto the bamboo-based hard carbon sheet precursor; and, An elastic buffer is provided at the upper end of the graphite electrode and is configured corresponding to the pressure rod; The pressure bar is used to apply a preset pressure to the graphite electrode through the elastic buffer, so that the elastic buffer generates elastic force. When current is passed through the graphite electrode to generate resistance heat and heat the bamboo-based hard carbon sheet precursor at high temperature, the bamboo-based hard carbon sheet precursor shrinks in volume due to heat. Under the elastic force of the elastic buffer, the graphite electrode is pressed onto the bamboo-based hard carbon sheet precursor, so that the bamboo-based hard carbon sheet precursor is formed into the bamboo-based hard carbon material under high temperature and pressure.

[0012] Optionally, the elastic buffer includes an upper plate, a lower plate, and an elastic element. The upper plate and the lower plate are spaced apart in the vertical direction. The lower plate is located at the upper end of the graphite electrode, and the elastic element is located between the upper plate and the lower plate.

[0013] Optionally, the waste processing unit includes: A pulverizer, connected to the bamboo pretreatment unit, is used to pulverize the bamboo-based residue output from the bamboo pretreatment unit; A dryer, connected to the pulverizer, the pneumatic pyrolysis zone, and the cooling zone, is used to dry the pulverized bamboo-based residue input from the pulverizer using high-temperature pyrolysis gas input from the pneumatic pyrolysis zone and hot air input from the cooling zone; and, A molding machine, connected to the dryer, is used to obtain the molded granules from the bamboo-based residue after high-pressure drying.

[0014] This invention also provides a method for co-producing bamboo-based hard carbon and shaped pellets, applicable to a bamboo-based hard carbon and shaped pellet co-production system, the method comprising the following steps: The main raw material is separated using a bamboo pretreatment unit to obtain bamboo white blocks and bamboo base residue; The bamboo white blocks are transported to a heat treatment furnace. First, they are dehydrated and pre-carbonized in the gas pressure baking zone of the heat treatment furnace to obtain baked bamboo white blocks. Then, they are pyrolyzed at high temperature in the gas pressure pyrolysis zone of the heat treatment furnace to obtain carbonized bamboo white blocks. Then, they are cooled by cold air in the cooling zone of the heat treatment furnace to obtain bamboo-based hard carbon sheet precursors. The bamboo-based hard carbon sheet precursors are then transported to a transient Joule thermal carbonization unit and subjected to high temperature and pressure using Joule hot pressing technology to obtain bamboo-based hard carbon material with a closed-cell structure. The bamboo-based residue is transported to the residue processing unit, where it is first crushed, then dried using high-temperature pyrolysis gas from the pneumatic pyrolysis zone and hot air from the cooling zone. Finally, the dried bamboo-based residue is subjected to high pressure to prepare shaped granules.

[0015] In the technical solution of this invention, the main raw material is separated by the bamboo pretreatment unit to obtain bamboo white blocks and bamboo-based residues. The bamboo white blocks are then heat-treated by a heat treatment furnace and a transient Joule thermal carbonization unit to prepare bamboo-based hard carbon material with a closed-cell structure, realizing the whole-chain preparation from biomass raw materials to high-performance anode materials. At the same time, the bamboo-based residues are processed by the residue treatment unit to prepare shaped granules. During the preparation process, the high-temperature pyrolysis gas input from the pressure pyrolysis zone and the hot air input from the cooling zone are used as drying heat sources to achieve self-sufficiency in thermal energy. Thus, the bamboo-based hard carbon and shaped granule co-production system provided by this invention not only solves the problems of poor product consistency and lack of efficient conversion methods from precursors to high-performance final anode materials in the existing bamboo-based hard carbon preparation process, but also realizes the high-value utilization of all components of bamboo materials through the coupling of material flow and energy flow, solving the problems of low resource utilization and high system energy consumption, and greatly improving the overall economic benefits and environmental protection level of the industrial chain. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, 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 the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a partial structural schematic diagram of an embodiment of the bamboo-based hard carbon and molded pellet co-production system provided by the present invention. Figure 2 for Figure 1 Schematic diagram of the structure of the pyrolysis reactor; Figure 3 for Figure 2 Top view of the pyrolysis reactor; Figure 4 for Figure 2 A partial structural diagram of the pyrolysis reactor; Figure 5 This is a partial structural schematic diagram of an embodiment of the bamboo-based hard carbon and molded pellet co-production system provided by the present invention. Figure 6 The flowchart shows the method for co-producing bamboo-based hard carbon and molded granules provided by the present invention.

[0018] Explanation of icon numbers: 100. Co-production system of bamboo-based hard carbon and molded pellets; 1. Bamboo pretreatment unit; 2. Heat treatment furnace; 21. Pressure baking zone; 22. Pressure pyrolysis zone; 23. Cooling zone; 24. Loading zone; 3. Transient Joule thermal carbonization unit; 31. Vacuum hood; 32. Pressure rod; 33. Insulating base; 34. Quartz tube; 35. Graphite electrode; 36. Elastic buffer; 361. Upper plate; 362. Lower plate; 363. Elastic element. 4. Waste material processing unit; 5. Pyrolysis reactor; 51. Outer protective vessel body; 52. Vessel cover; 53. Tubular reaction chamber; 531. Tubular body; 532. Fixed heating column; 5321. Resistance heating element; 5322. Insulating and thermally conductive ceramic layer; 533. Rotary stirring shaft; 54. Pressure limiting valve; 55. Active magnetic rotor; 56. Driven magnetic rotor. 6. Running track.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0022] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0023] With the booming development of new energy vehicles and grid energy storage industries, the demand for high-performance secondary battery anode materials has increased significantly. Among them, hard carbon, due to its unique interlayer structure, excellent rate performance, and low-cost potential, has become the preferred anode material for next-generation sodium-ion batteries. However, the industrialization of hard carbon currently faces challenges such as limited precursor sources and high production costs, which directly restrict the cost competitiveness of sodium-ion batteries. In the process of continuous technological progress and the advancement of dual-carbon goals, finding green, renewable, and inexpensive biomass sources as hard carbon precursors has become an industry consensus. Bamboo, as a biomass resource with a short growth cycle, huge yield, and rich in cellulose and lignin, is considered an ideal raw material for preparing high-quality hard carbon.

[0024] However, the preparation of bamboo-based hard carbon faces multiple bottlenecks. On the raw material side, bamboo itself has a low thermal conductivity, and the physicochemical properties of different parts (bamboo white, bamboo nodes, and bamboo green) vary greatly, leading to existing preparation technologies consistently facing the dual challenges of poor product consistency and low resource utilization. Regarding system energy efficiency and integration, existing technologies also have significant limitations. The large amount of high-temperature volatiles (pyrolysis gas) generated during pyrolysis and the waste heat from the cooling stage are usually directly emitted, resulting in low system energy efficiency.

[0025] In view of this, the present invention provides a bamboo-based hard carbon and shaped granule co-production system 100. Figures 1 to 5 This is an embodiment of the bamboo-based hard carbon and molded granule co-production system 100 provided by the present invention.

[0026] Please see Figure 1 and Figure 5 The bamboo-based hard carbon and shaped pellet co-production system 100 includes a bamboo pretreatment unit 1, a heat treatment furnace 2, a transient Joule heating carbonization unit 3, and a residue processing unit 4. The bamboo pretreatment unit 1 is used to separate the main raw material into bamboo white blocks and bamboo-based residue. The heat treatment furnace 2 extends along a first direction and is sequentially provided with a pressure baking zone 21, a pressure pyrolysis zone 22, and a cooling zone 23 along the first direction. The pressure baking zone 21 is used to dehydrate and pre-carbonize the bamboo white blocks to obtain baked bamboo white blocks. The pressure pyrolysis zone 22 is used to generate high-temperature pyrolysis gas to heat the baked bamboo white blocks to obtain carbonized bamboo white blocks. The cooling zone 23 is used to cool the carbonized bamboo white blocks with cold air to obtain bamboo-based hard carbon. A carbon sheet precursor is formed, and the cold air is converted into hot air; the transient Joule thermal carbonization unit 3 is connected to the cooling zone 23, and is used to pressurize the bamboo-based hard carbon sheet precursor at high temperature using Joule hot pressing technology to obtain bamboo-based hard carbon material with a closed-cell structure; the residue processing unit 4 is connected to the bamboo pretreatment unit 1, the pneumatic pyrolysis zone 22, and the cooling zone 23, and is used to crush the bamboo-based residue output from the bamboo pretreatment unit 1, and use the high-temperature pyrolysis gas input from the pneumatic pyrolysis zone 22 and the hot air input from the cooling zone 23 to dry the crushed bamboo-based residue, and to prepare shaped particles by high pressure on the dried bamboo-based residue; wherein, the first direction is perpendicular to the up and down direction.

[0027] In the technical solution of this invention, the bamboo pretreatment unit 1 separates the main raw material to obtain bamboo white blocks and bamboo-based residues. Then, the bamboo white blocks are heat-treated using a heat treatment furnace 2 and a transient Joule thermal carbonization unit 3 to prepare bamboo-based hard carbon material with a closed-cell structure, realizing the whole-chain preparation from biomass raw materials to high-performance anode materials. At the same time, the bamboo-based residues are processed by a residue treatment unit 4 to prepare shaped granules. During the preparation process, the high-temperature pyrolysis gas input from the pressure pyrolysis zone 22 and the hot air input from the cooling zone 23 are used as drying heat sources to achieve self-sufficiency in thermal energy. Thus, the bamboo-based hard carbon and shaped granule co-production system 100 provided by this invention not only solves the problems of poor product consistency and lack of efficient conversion methods from precursors to high-performance final anode materials in the existing bamboo-based hard carbon preparation process, but also realizes the high-value utilization of all components of bamboo through the coupling of material flow and energy flow, solving the problems of low resource utilization and high system energy consumption, and greatly improving the overall economic benefits and environmental protection level of the industrial chain.

[0028] It should be noted that, in one embodiment of the present invention, the heat treatment furnace 2, serving as the thermal environment carrier of the system, has a tunnel-like structure with a total length of approximately 50m. Its outer shell is welded from carbon steel, and its inner wall is provided with a 300mm thick aluminum silicate fiber insulation layer. The pressure baking zone 21 is approximately 15m long and has a set temperature of 200℃~300℃; the pressure pyrolysis zone 22 is approximately 20m long and has a set temperature of 450℃~750℃, and is a key area for the formation of hard carbon microcrystalline structures; the cooling zone 23 is approximately 10m long.

[0029] More specifically, the heat treatment furnace 2 has a first heat treatment chamber, a second heat treatment chamber and a third heat treatment chamber distributed sequentially along the first direction. The gas pressure baking zone 21 is formed in the first heat treatment chamber, the gas pressure pyrolysis zone 22 is formed in the second heat treatment chamber, and the cooling zone 23 is formed in the third heat treatment chamber.

[0030] Furthermore, the second heat treatment chamber is provided with a pyrolysis gas outlet and is connected to the waste material processing unit 4 through a pyrolysis gas pipeline, so that the high-temperature pyrolysis gas in the second heat treatment chamber is input into the waste material processing unit 4 through the pyrolysis gas pipeline; the third heat treatment chamber is provided with a cold air inlet and a hot air outlet, the cold air inlet allows cold air from the outside to flow into the third heat treatment chamber, and the hot air outlet is connected to the waste material processing unit 4 through a hot air pipeline, so that the hot air in the third heat treatment chamber is input into the waste material processing unit 4 through the hot air pipeline.

[0031] For details, please refer to Figure 1The heat treatment furnace 2 is equipped with a running track 6, which extends along the first direction. The bamboo-based hard carbon and shaped granule co-production system 100 also includes a pyrolysis reactor 5, which is slidably mounted on the running track 6 so as to slide relative to the heat treatment furnace 2 along the first direction. It is used to transport the bamboo blocks through the pressure baking zone 21, the pressure pyrolysis zone 22, and the cooling zone 23 in sequence to obtain the bamboo-based hard carbon sheet precursor. This method helps to improve efficiency and reduce time costs.

[0032] It should be noted that, in this invention, the sliding of the pyrolysis reactor 5 on the running track 6 can be done manually or automatically.

[0033] For further details, please refer to Figures 2 to 4 The pyrolysis reactor 5 includes an outer protective vessel body 51, a vessel cover 52, a reaction assembly, and a pressure limiting assembly. The outer protective vessel body 51 has an upper opening; the vessel cover 52 is placed over the upper opening; the reaction assembly is located inside the outer protective vessel body 51 and connected to the vessel cover 52, and includes a plurality of tubular reaction chambers 53 spaced apart. Each tubular reaction chamber 53 includes a tube body 531, a fixed heating column 532, and a plurality of rotating stirring shafts 533. The tube body 531 is used to accommodate the bamboo white block, and the top wall of the tube body 531 has an exhaust port. The fixed heating column 532 and the plurality of rotating stirring shafts 533 are located inside the tube body 531. Multiple rotating stirring shafts 533 are disposed on the outer periphery of the fixed heating column 532. Each rotating stirring shaft 533 can rotate relative to the tube body 531 around its axis. When the pyrolysis reactor 5 moves to the gas pressure pyrolysis zone 22, the fixed heating column 532 is in a heating state, and the rotating stirring shaft 533 is in a rotating state to agitate the bamboo blocks inside the tube body 531. The pressure limiting component includes multiple pressure limiting valves 54, which are disposed one-to-one at the exhaust ports of multiple tube bodies 531. When the pressure inside the tube body 531 is greater than a preset value, the pressure limiting valve 54 is in an open state to allow the gas inside the tube body 531 to be discharged.

[0034] Thus, by setting a fixed heating column 532 and a rotating stirring shaft 533 inside the tubular reaction chamber 53, an "internal heating + stirring" structure is formed, which can solve the problem of uneven heat transfer in bamboo and produce a hard carbon precursor with extremely high uniformity. At the same time, the fixed heating column 532 (stator) and the external track furnace form a bidirectional temperature control field, which, together with the strong shear flow field generated by the stirring of multiple rotating stirring shafts 533 (rotors), can completely solve the heat transfer problem of "external charring and internal carbonization" during biomass pyrolysis. Furthermore, by combining the pressure limiting valve 54 with precise control of the pyrolysis gas pressure inside the tubular reaction chamber 53, the bamboo blocks are carbonized under a constant micro-positive pressure and uniform heating environment, further improving the high quality of the hard carbon precursor.

[0035] In addition, the pressure limiting valve 54 is used to maintain the gas pressure in the tubular reaction chamber 53 within a preset positive pressure range when the gas pressure baking zone 21 and the gas pressure pyrolysis zone 22 are working, and to control the discharge rate of volatile gas.

[0036] Furthermore, in one embodiment of the present invention, the outer protective vessel body 51 is made of 304 stainless steel, and its main function is to provide heat preservation and protection, preventing damage to the internal workpieces and mutual interference.

[0037] Specifically, in this invention, the number of rotating stirring shafts 533 is not limited and can be two, three, four, or more. More specifically, in one embodiment of this invention, four rotating stirring shafts 533 are provided, symmetrically distributed around the fixed heating column 532. Each rotating stirring shaft 533 has multiple stirring blades spaced axially, and the rotation trajectory of the stirring blades covers the annular space between the fixed heating column 532 and the wall of the tube body 531, thereby stirring the material in the annular space.

[0038] Specifically, in this invention, the tube body 531 should possess anti-creep properties for long-term operation at a high temperature of 800℃, and be resistant to corrosion from acidic volatiles (including acetic acid and tar) generated during the pyrolysis of bamboo. More specifically, in one embodiment of this invention, the tube body 531 is made of high-temperature resistant 310S austenitic stainless steel or Inconel 625 nickel-based alloy, capable of withstanding corrosion from acetic acid and tar during pyrolysis and high-temperature creep.

[0039] Specifically, in this invention, the number and location of the multiple tubular reaction chambers 53 inside the outer protective vessel body 51 are not limited. They can be arranged in an array of "1+4" (i.e., five tubular reaction chambers 53 are arranged inside the outer protective vessel body 51, one of which is located at the center of the outer protective vessel body 51 and four tubular reaction chambers 53 surround the outer perimeter) or "1+6" (i.e., seven tubular reaction chambers 53 are arranged inside the outer protective vessel body 51, one of which is located at the center of the outer protective vessel body 51 and six tubular reaction chambers 53 surround the outer perimeter).

[0040] Specifically, in this invention, the opening pressure of the pressure limiting valve 54, i.e., the set value, is set to 0.1-0.5 MPa. When the pressure inside the pipe body 531 is greater than the opening pressure, i.e., the set value, the gas is automatically discharged, ensuring that the bamboo is always carbonized under a slightly positive pressure environment, which is beneficial to improving the residual carbon rate and interlayer uniformity of hard carbon.

[0041] For details, please refer to Figure 2 and Figure 4 In one embodiment of the present invention, the pyrolysis reactor 5 further includes a plurality of magnetic drive components. The plurality of magnetic drive components are disposed on the reactor cover 52 and are drivenly connected to the plurality of rotating stirring shafts 533 one by one. Each magnetic drive component includes an active magnetic rotor 55, a driven magnetic rotor 56 and a drive motor. The active magnetic rotor 55 is disposed on the upper side of the reactor cover 52, and the driven magnetic rotor is disposed on the lower side of the reactor cover 52 corresponding to the active magnetic rotor 55 and is sleeved on the outside of the rotating stirring shaft 533. The drive motor is drivenly connected to the active magnetic rotor 55 to drive the active magnetic rotor 55 to drive the driven magnetic rotor 56 to rotate, so that the driven magnetic rotor 56 drives the rotating stirring shaft 533 to rotate around its axis.

[0042] More specifically, the active magnetic rotor 55 penetrates the sealing cover through magnetic coupling and drives the passive magnetic rotor to rotate, thereby driving the rotating stirring shaft 533 to rotate at a low speed of 5~20 r / min.

[0043] More specifically, both the active magnetic rotor 55 and the passive magnetic rotor are made of high-temperature resistant samarium cobalt permanent magnet material with a Curie temperature higher than 350°C to prevent high-temperature demagnetization.

[0044] Specifically, each of the tubular reaction chambers 53 has a thermal expansion gap between its bottom end and the bottom wall of the outer protective vessel 51 to prevent equipment damage caused by high-temperature deformation.

[0045] Furthermore, the size of the thermal expansion gap is 50mm~100mm.

[0046] For details, please refer to Figure 4The fixed heating column 532 includes a resistance heating element 5321 and an insulating and thermally conductive ceramic layer 5322. The insulating and thermally conductive ceramic layer 5322 is wrapped around the resistance heating element 5321 to ensure that heat can be efficiently radiated and conducted to the material, while ensuring electrical insulation safety.

[0047] More specifically, the material and properties of the insulating and thermally conductive ceramic layer 5322 must meet the following requirements: thermal conductivity under standard operating conditions not less than 150 W / (m·K), and volume resistivity not less than 1.0 × 10⁻⁶. 12 The insulation temperature is measured in Ω·cm to ensure electrical insulation safety between the resistance heating element 5321 and the external stirring assembly under high-temperature conditions. Furthermore, the insulating and thermally conductive ceramic layer 5322 is made of aluminum nitride or silicon carbide material.

[0048] Specifically, the heat treatment furnace 2 is also provided with a loading area 24, which is located on the upstream side of the first heat treatment chamber and is used to load and close the pyrolysis reactor 5.

[0049] For details, please refer to Figure 5 The transient Joule heating carbonization unit 3 includes a vacuum chamber 31, a pressure rod 32, an insulating base 33, a quartz tube 34, a graphite electrode 35, and an elastic buffer 36. The pressure rod 32 is inserted into the upper wall of the vacuum chamber 31 and can move relative to the vacuum chamber 31 in the vertical direction under force. The insulating base 33 is disposed on the bottom wall of the vacuum chamber 31. The quartz tube 34 is disposed on the insulating base 33 and extends in the vertical direction, and is used to accommodate the bamboo-based hard carbon sheet precursor. The graphite electrode 35 is inserted into the quartz tube 34 in the vertical direction and pressed onto the bamboo-based hard carbon sheet precursor. The elastic buffer 36 is disposed at the upper end of the graphite electrode 35 and is disposed corresponding to the pressure rod 32. The pressure rod 32 is used to apply a preset pressure to the graphite electrode 35 through the elastic buffer 36, so that the elastic buffer 36 generates elastic force. When current is passed through the graphite electrode 35 to generate resistance heat and heat the bamboo-based hard carbon sheet precursor at high temperature, the bamboo-based hard carbon sheet precursor shrinks in volume due to heat. Under the elastic force of the elastic buffer 36, the graphite electrode 35 is pressed onto the bamboo-based hard carbon sheet precursor, so that the bamboo-based hard carbon sheet precursor is formed into the bamboo-based hard carbon material under high temperature and pressure.

[0050] Thus, the elastic buffer 36 is used to compensate for displacement under the continuous pressure of the pressure rod 32 when the bamboo-based hard carbon sheet precursor shrinks in volume due to heat, thereby maintaining close contact between the graphite electrode 35 and the bamboo-based hard carbon sheet precursor.

[0051] It should be noted that the Joule hot pressing technology described above specifically involves: after the vacuum chamber 31 is evacuated or a protective atmosphere is introduced, a preset pressure is applied through the pressure rod 32, and a large current pulse is applied to the graphite electrode 35. Utilizing the resistance heat of the bamboo-based hard carbon sheet precursor itself, the bamboo-based hard carbon sheet precursor can be rapidly heated to approximately 1600°C within about 20 seconds. The thermal shock effect generated by this rapid heating, along with the atomic rearrangement under pressure, can effectively repair carbon microcrystal defects in a very short time and induce the formation of bamboo-based hard carbon material with a good closed-pore structure inside the bamboo-based hard carbon sheet precursor. Compared to traditional long-term high-temperature carbonization, this process not only significantly reduces energy consumption and time costs but also significantly improves the compaction density and sodium ion storage performance of the hard carbon material.

[0052] For further details, please refer to Figure 5 In one embodiment of the present invention, the elastic buffer 36 includes an upper plate 361, a lower plate 362 and an elastic element 363. The upper plate 361 and the lower plate 362 are spaced apart in the vertical direction. The lower plate 362 is disposed at the upper end of the graphite electrode 35, and the elastic element 363 is disposed between the upper plate 361 and the lower plate 362.

[0053] For further details, please refer to Figure 5 In one embodiment of the present invention, the elastic element 363 is a spring. Of course, the elastic element 363 can also be a structure made of elastic material such as a rubber pad.

[0054] Specifically, the residue processing unit 4 includes a crusher, a dryer, and a molding machine. The crusher is connected to the bamboo pretreatment unit 1 and is used to crush the bamboo-based residue output by the bamboo pretreatment unit 1. The dryer is connected to the crusher, the pressure pyrolysis zone 22, and the cooling zone 23 and is used to dry the crushed bamboo-based residue input by the crusher using the high-temperature pyrolysis gas input by the pressure pyrolysis zone 22 and the hot air input by the cooling zone 23. The molding machine is connected to the dryer and is used to obtain the molded particles from the bamboo-based residue dried under high pressure.

[0055] Thus, the specific processing process of the residual material processing unit 4 is as follows: the bamboo-based residual material, composed of low-value by-products such as bamboo joints, bamboo green, and bamboo shavings, is crushed by the crusher and then enters the dryer. The crushed bamboo-based residual material is dried by the heat energy of the combination of high-temperature pyrolysis gas and hot air, reducing the moisture content of the bamboo-based residual material to below 10%. The dried bamboo-based residual material is then pressed into high-density biomass pellets with a diameter of 6-8 mm by the molding machine under high pressure, realizing the full resource utilization of waste.

[0056] Furthermore, the dryer is equipped with a mixing chamber, which is connected to the second heat treatment chamber via the pyrolysis gas pipeline mentioned above, and to the third heat treatment chamber via the hot air pipeline mentioned above. That is, the high-temperature pyrolysis gas (temperature about 300-500℃, containing combustible components such as CO, H2 and methane) in the pneumatic pyrolysis zone 22 and the hot air (temperature about 150-200℃) in the cooling zone 23 are combined in the mixing chamber to form a drying heat source.

[0057] Furthermore, a burner is provided at the front end of the mixing chamber. When there are a large number of combustible components in the high-temperature pyrolysis gas, the burner is ignited to release more chemical energy.

[0058] Specifically, the bamboo pretreatment unit 1 includes a segmenting machine, a node removal machine, and a green leaf removal machine, which mechanically and physically separate the main raw material, namely the original bamboo, into high-value "bamboo white blocks" and low-value "bamboo base residue" (i.e. bamboo nodes, bamboo green leaves, and debris).

[0059] The present invention also provides a method for co-producing bamboo-based hard carbon and molded granules, applicable to the bamboo-based hard carbon and molded granule co-production system 100 described above.

[0060] Please see Figure 6 The method for co-producing bamboo-based hard carbon and molded granules includes the following steps: Step S100: Use bamboo pretreatment unit 1 to separate the main raw material to obtain bamboo white block and bamboo base residue.

[0061] In this step, a segmenting machine, a node removal machine, and a green leaf removal machine are used to mechanically and physically separate the main raw material, namely the original bamboo, into high-value "bamboo white blocks" and low-value "bamboo base residue" (i.e., bamboo nodes, bamboo green leaves, and debris).

[0062] Step S200: The bamboo white block is transported to the heat treatment furnace 2. First, it is dehydrated and pre-carbonized in the pressure baking zone 21 of the heat treatment furnace 2 to obtain baked bamboo white block. Then, it is heated at high temperature in the pressure pyrolysis zone 22 of the heat treatment furnace 2 to obtain carbonized bamboo white block. Then, it is cooled by cold air in the cooling zone 23 of the heat treatment furnace 2 to obtain bamboo-based hard carbon sheet precursor. Then, the bamboo-based hard carbon sheet precursor is transported to the transient Joule thermal carbonization unit 3 and subjected to high temperature and pressure through Joule hot pressing technology to obtain bamboo-based hard carbon material with closed-cell structure.

[0063] This step is the main product route. Bamboo white blocks are packaged in a pyrolysis reactor 5 and passed through a pressure baking zone 21, a pressure pyrolysis zone 22 and a cooling zone 23 in sequence via a running track 6 to obtain a bamboo-based hard carbon sheet precursor. The bamboo-based hard carbon sheet precursor is then taken out and sent to a transient Joule thermal carbonization unit 3 for high-temperature and high-pressure Joule hot pressing technology to finally obtain a bamboo-based hard carbon material with a closed-cell structure.

[0064] More specifically, the pyrolysis reactor 5 enters the heat treatment furnace 2 along the running track 6. In the gas pressure baking zone 21, the entire pyrolysis reactor 5 is heated to 300°C using an external electric heating jacket, and the bamboo blocks are sealed in the reactor for high-pressure baking at 300°C. Subsequently, it enters the gas pressure pyrolysis zone 22, where the fixed heating column 532 inside the pyrolysis reactor 5 is energized and heated, forming a bidirectional heat source with the external furnace, raising the temperature to 450-750°C. At this time, the rotating stirring shaft 533 rotates, continuously turning the bamboo blocks to prevent local overheating and coking; simultaneously, the pressure limiting valve 54 controls the pressure inside the tubular reaction chamber 53 to obtain the desired product. It then enters the cooling zone 23, where it is cooled by cold air to obtain bamboo-based hard carbon sheet precursors, which are then sent to the transient Joule thermal carbonization unit 3 and subjected to ultra-high temperature pulse treatment at 1600°C to finally obtain high-performance hard carbon with a closed-pore structure.

[0065] Step S300: The bamboo-based residue is transported to the residue processing unit 4, first crushed, then dried using the high-temperature pyrolysis gas input from the pneumatic pyrolysis zone 22 and the hot air input from the cooling zone 23, and then the dried bamboo-based residue is subjected to high pressure to obtain shaped particles.

[0066] This step is a by-product route. The bamboo-based residue generated during pretreatment is sent to the residue treatment unit 4, where it is first crushed by a pulverizer and then dried by a dryer to dry the bamboo joint / bamboo green powder to a moisture content of less than 10%. The heat source used in the drying process comes directly from the waste heat generated in the main product route, namely the pyrolysis gas generated in the "pressure pyrolysis" process and the hot air generated in the "cooling" process. The dried powder is pressed by a molding machine to obtain shaped particles, thus realizing a dual closed loop of material flow and energy flow.

[0067] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A system for the co-production of bamboo-based hard carbon and molded pellets, characterized in that, The bamboo-based hard carbon and shaped pellet co-production system includes: The bamboo pretreatment unit is used to separate the main raw material into bamboo white blocks and bamboo base residue; A heat treatment furnace extends along a first direction and is provided in sequence along the first direction with a pressure baking zone, a pressure pyrolysis zone, and a cooling zone. The pressure baking zone is used to dehydrate and pre-carbonize the bamboo white blocks to obtain baked bamboo white blocks. The pressure pyrolysis zone is used to pyrolyze the baked bamboo white blocks to obtain carbonized bamboo white blocks and obtain high-temperature pyrolysis gas. The cooling zone is used to cool the carbonized bamboo white blocks with cold air to obtain bamboo-based hard carbon sheet precursors and to convert the cold air into hot air. A transient Joule thermal carbonization unit, connected to the cooling zone, is used to obtain a bamboo-based hard carbon material with a closed-cell structure by high-temperature and high-pressure pressing of the bamboo-based hard carbon sheet precursor using Joule hot pressing technology; and... The residue processing unit is connected to the bamboo pretreatment unit, the pneumatic pyrolysis zone, and the cooling zone. It is used to crush the bamboo-based residue output from the bamboo pretreatment unit, and use the high-temperature pyrolysis gas input from the pneumatic pyrolysis zone and the hot air input from the cooling zone to dry the crushed bamboo-based residue. The dried bamboo-based residue is then subjected to high pressure to prepare shaped particles. The first direction is perpendicular to the up and down direction.

2. The bamboo-based hard carbon and shaped pellet co-production system as described in claim 1, characterized in that, The heat treatment furnace is equipped with a running track, which extends along the first direction. The bamboo-based hard carbon and shaped granule co-production system also includes a pyrolysis reactor, which is slidably installed on the running track so that it can slide relative to the heat treatment furnace along the first direction. It is used to transport the bamboo white blocks through the pressure baking zone, the pressure pyrolysis zone and the cooling zone in sequence to obtain the bamboo-based hard carbon sheet precursor.

3. The bamboo-based hard carbon and shaped pellet co-production system as described in claim 2, characterized in that, The pyrolysis reactor includes: The outer protective vessel body has an opening at the top. A lid is fitted over the upper opening; The reaction assembly, housed within the outer protective vessel and connected to the vessel lid, includes a plurality of spaced-apart tubular reaction chambers. Each tubular reaction chamber comprises a tube body, a fixed heating column, and a plurality of rotating stirring shafts. The tube body is used to contain the bamboo white blocks, and the top wall of the tube body has an exhaust port. The fixed heating column and the plurality of rotating stirring shafts are located within the tube body, with the plurality of rotating stirring shafts positioned around the outer periphery of the fixed heating column. Each rotating stirring shaft is rotatable relative to the tube body around its axis. When the pyrolysis reactor moves to the gas pressure pyrolysis zone, the fixed heating column is in a heating state, and the rotating stirring shafts are in a rotating state to agitate the bamboo white blocks within the tube body; and... The pressure limiting assembly includes multiple pressure limiting valves, which are respectively located at the exhaust ports of multiple pipes. When the pressure inside the pipe is greater than a preset value, the pressure limiting valve is in the open state to allow the gas inside the pipe to be discharged.

4. The bamboo-based hard carbon and shaped pellet co-production system as described in claim 3, characterized in that, The pyrolysis reactor also includes multiple magnetic drive components, which are disposed on the reactor lid and driven by a plurality of rotating stirring shafts. Each magnetic drive component includes an active magnetic rotor, a driven magnetic rotor, and a drive motor. The active magnetic rotor is disposed on the upper side of the reactor lid, and the driven magnetic rotor is disposed on the lower side of the reactor lid, corresponding to the active magnetic rotor, and sleeved on the outside of the rotating stirring shaft. The drive motor is driven by the active magnetic rotor to drive the active magnetic rotor to rotate the driven magnetic rotor, so that the driven magnetic rotor drives the rotating stirring shaft to rotate around its axis.

5. The bamboo-based hard carbon and shaped pellet co-production system as described in claim 3, characterized in that, There is a thermal expansion gap between the bottom end of each tubular reaction chamber and the bottom wall of the outer protective vessel.

6. The bamboo-based hard carbon and shaped pellet co-production system as described in claim 3, characterized in that, The fixed heating column includes a resistance heating element and an insulating thermally conductive ceramic layer, which is wrapped around the resistance heating element.

7. The bamboo-based hard carbon and shaped pellet co-production system as described in claim 1, characterized in that, The transient Joule thermal carbonization unit includes: Vacuum enclosure; A pressure rod is inserted into the upper wall of the vacuum chamber and can move relative to the vacuum chamber in the vertical direction under force. An insulating base is disposed on the bottom wall of the vacuum chamber; A quartz tube is disposed on the insulating base and extends in the vertical direction, and is used to accommodate the bamboo-based hard carbon sheet precursor. A graphite electrode is inserted into the quartz tube along the vertical direction and pressed onto the bamboo-based hard carbon sheet precursor; and, An elastic buffer is provided at the upper end of the graphite electrode and is configured corresponding to the pressure rod; The pressure bar is used to apply a preset pressure to the graphite electrode through the elastic buffer, so that the elastic buffer generates elastic force. When current is passed through the graphite electrode to generate resistance heat and heat the bamboo-based hard carbon sheet precursor at high temperature, the bamboo-based hard carbon sheet precursor shrinks in volume due to heat. Under the elastic force of the elastic buffer, the graphite electrode is pressed onto the bamboo-based hard carbon sheet precursor, so that the bamboo-based hard carbon sheet precursor is formed into the bamboo-based hard carbon material under high temperature and pressure.

8. The bamboo-based hard carbon and shaped pellet co-production system as described in claim 7, characterized in that, The elastic buffer includes an upper plate, a lower plate, and an elastic element. The upper plate and the lower plate are spaced apart in the vertical direction. The lower plate is located at the upper end of the graphite electrode, and the elastic element is located between the upper plate and the lower plate.

9. The bamboo-based hard carbon and shaped pellet co-production system as described in claim 1, characterized in that, The waste processing unit includes: A pulverizer, connected to the bamboo pretreatment unit, is used to pulverize the bamboo-based residue output from the bamboo pretreatment unit; A dryer, connected to the pulverizer, the pressure pyrolysis zone, and the cooling zone, is used to dry the pulverized bamboo-based residue input from the pulverizer using high-temperature pyrolysis gas input from the pressure pyrolysis zone and hot air input from the cooling zone; and, A molding machine, connected to the dryer, is used to obtain the molded granules from the bamboo-based residue after high-pressure drying.

10. A method for co-producing bamboo-based hard carbon and molded pellets, applicable to the bamboo-based hard carbon and molded pellet co-production system as described in any one of claims 1-9, characterized in that, The method for co-producing bamboo-based hard carbon and molded granules includes the following steps: The main raw material is separated using a bamboo pretreatment unit to obtain bamboo white blocks and bamboo base residue; The bamboo white blocks are transported to a heat treatment furnace. First, they are dehydrated and pre-carbonized in the gas pressure baking zone of the heat treatment furnace to obtain baked bamboo white blocks. Then, they are heated at high temperature in the gas pressure pyrolysis zone of the heat treatment furnace to obtain carbonized bamboo white blocks. Then, they are cooled by cold air in the cooling zone of the heat treatment furnace to obtain bamboo-based hard carbon sheet precursors. The bamboo-based hard carbon sheet precursors are then transported to a transient Joule thermal carbonization unit and subjected to high temperature and pressure using Joule hot pressing technology to obtain bamboo-based hard carbon material with a closed-cell structure. The bamboo-based residue is transported to the residue processing unit, where it is first crushed, then dried using high-temperature pyrolysis gas from the pneumatic pyrolysis zone and hot air from the cooling zone. Finally, the dried bamboo-based residue is subjected to high pressure to obtain shaped granules.

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