Internal source steam in-situ braking expansion device and hard carbon material preparation method

Abstract

The invention discloses an endogenous steam in-situ braking expansion device and a hard carbon material preparation method, and belongs to the technical field of biomass pretreatment, and the endogenous steam in-situ braking expansion device comprises a steam explosion reaction cabin and a water storage cabin which are communicated. An electric heating device is arranged outside the steam explosion reaction cabin, the steam explosion reaction cabin is communicated with the water storage cabin, and an inductance heating device is arranged outside the water storage cabin. The brake expansion device adopts a mode of combining electric heating and inductive heating, water vapor is generated in situ, and energy loss caused by vapor condensation is effectively reduced. Compared with a traditional steam explosion machine, the steam explosion machine has the advantages that energy consumption is effectively reduced, materials can be conveniently fed and discharged, and meanwhile the problem that steam is generated, enters the steam explosion reaction cabin, is condensed and drips on the materials, and consequently treatment is not uniform is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biomass pretreatment, and particularly relates to an endogenous steam in-situ instantaneous expansion device and a hard carbon material preparation method. BACKGROUND

[0002] The steam explosion pretreatment equipment is a steam explosion device capable of uniformly introducing steam to ensure that the temperature of the materials in the equipment is uniform, and plays a key role in the processing of biomass-based materials. After the plant fibers are fully treated by steam and instantaneously depressurized, the dense microstructure thereof can be effectively destroyed, thereby providing good treatment conditions for the biomass-based precursors in multiple scenarios. The horizontal endogenous steam in-situ instantaneous expansion device is a device that can be used to prepare precursors of biomass in multiple scenarios, and can prepare biomass carbon material precursors for different purposes according to different needs. By adding an appropriate amount of water to achieve the required pressure for the reaction, and then completing the pressure maintaining treatment for a certain time, the energy consumption and subsequent wastewater treatment consumption can be effectively saved. The utility model patent CN221523151U discloses a steam explosion device for fiber material processing, a plurality of steam introduction channels are added in the steam explosion device to ensure that the steam uniformly penetrates the materials. The device has obvious advantages in processing large-particle-size biomass-based materials, and can effectively solve the problem that the materials are pressed and stacked with each other, thereby causing the steam to be unable to uniformly penetrate the materials. However, in the process, the consumption of water vapor is not significantly reduced, and the steam is still generated by an external boiler, and the generated steam is used to heat the materials, thereby reducing the processing efficiency. The invention patent CN118105930A discloses an endogenous steam in-situ instantaneous expansion device and method for biomass pretreatment, which significantly reduces the energy consumption compared with the traditional steam explosion device. However, the device is not conducive to the subsequent recovery of the materials, and the biomass raw materials are easily concentrated on the inner wall of the reactor; and the hard carbon negative electrode material precursor for sodium ion batteries prepared by the method needs to be further hydrothermally carbonized before the secondary carbonization step, and the operation process is complicated. The invention patent CN118079847A discloses a biomass endogenous steam instantaneous expansion continuous complete device and intelligent control method, which has the advantages of convenient maintenance and easy operation compared with the traditional steam explosion device. However, the operation unit is too much, the maintenance cost is high, and the materials are easily adhered to the inner wall of the reaction chamber. In summary, the existing steam explosion machines generally have high energy consumption, insufficient treatment, and the materials in the steam explosion chamber are easily contacted with too much condensed water, and many other problems, which seriously affect the processing efficiency of the process and are not conducive to large-scale production and use. SUMMARY

[0003] The application provides an endogenous steam in-situ instantaneous expansion device and a hard carbon material preparation method, which solves the technical problems of high steam energy consumption and the materials in the steam explosion chamber being easily contacted with too much condensed water in the existing steam explosion technology.

[0004] In order to achieve the above object, the present application adopts the following technical solutions: In a first aspect, the present application provides an endogenous steam in-situ instantaneous expansion device, comprising a steam explosion reaction cabin, a buffer tank and a water storage cabin, the steam explosion reaction cabin is provided with a feeding port on one side and a pneumatic pressure relief valve on the other side, an external electric heating device is provided, and a water storage cabin is provided below; the pressure relief port of the pneumatic pressure relief valve is communicated with the buffer tank; the water storage cabin is communicated with the steam explosion reaction cabin, an inductive heating device is provided outside the water storage cabin, and a jacket for accommodating a cooling medium is provided outside the inductive heating device.

[0005] Further, the steam explosion reaction cabin is placed horizontally.

[0006] Further, the feeding port is provided with a quick-opening blind plate.

[0007] Further, a rapid pressure relief protection valve is provided above the steam explosion reaction cabin, and an electronic pressure detector for detecting the internal pressure of the steam explosion reaction cabin and a temperature sensor for detecting the internal temperature of the steam explosion reaction cabin are provided in the steam explosion reaction cabin.

[0008] Further, the steam explosion reaction cabin adopts a through-welding structure.

[0009] Further, the jacket is connected with a circulating water pump through a pipeline.

[0010] Further, an air inlet valve is provided above the steam explosion reaction cabin, and the air inlet valve is used for connecting a gas bottle for adjusting the reaction atmosphere.

[0011] In a second aspect, the present application provides a preparation method of hard carbon material based on the above-mentioned endogenous steam in-situ instantaneous expansion device, comprising the following steps: Water required for preparing the hard carbon material is injected into the water storage cabin through the feeding port, biomass is put into the material basket, and a plurality of material baskets are placed in the steam explosion reaction cabin, and the steam explosion reaction cabin is heated to above 100 DEG C by the electric heating device; The water in the water storage cabin is heated to the required temperature by the inductive heating device to generate a required amount of steam, and then pressure is maintained; when the pressure maintaining time reaches the set pressure maintaining time, the pneumatic pressure relief valve is opened to realize instantaneous pressure relief in the steam explosion reaction cabin, and a hard carbon material precursor is obtained; The hard carbon material precursor is dried and crushed to obtain a crushed hard carbon material precursor, and the crushed hard carbon material precursor is subjected to activation treatment in an inert gas atmosphere to obtain a hard carbon material.

[0012] Further, the material baskets are laid in a single layer in the steam explosion reaction cabin.

[0013] Further, the temperature of the activation treatment is 1100-1500 DEG C.

[0014] Compared with the prior art, the present application has at least the following beneficial technical effects: The endogenous steam in-situ instantaneous expansion device provided by the present application sets an electric heating device outside the steam explosion reaction cabin for preheating the steam explosion reaction cabin to avoid steam condensation after entering the steam explosion reaction cabin; the water storage cabin is heated by an electric induction device to accurately control the steam generation amount, and the water storage cabin is wrapped with a jacket structure outside, and a cooling medium circulates in the jacket to absorb the excess heat transferred to the outer wall of the water storage cabin during the operation of the electric induction heating device, thereby avoiding local overheating of the water storage cabin and ensuring uniform heating and vaporization of the water in the water storage cabin. The endogenous steam in-situ instantaneous expansion device provided by the present application only needs to add an appropriate amount of water, directly participates in the reaction in combination with the original water in the biomass, and can be heated by using two independent heating devices, without an external boiler, thereby significantly reducing the energy consumption compared with the traditional steam explosion machine. At the same time, the problem of uneven treatment of raw materials caused by steam generation, entering the steam explosion reaction cabin, condensation and dripping on the materials is effectively avoided. Different hard carbon material precursors required in different scenes can be prepared according to different needs.

[0015] Further, the steam explosion reaction cabin is matched with a clamp type quick-opening feed inlet with a quick-opening blind plate in the side direction, thereby avoiding the problems of traditional vertical equipment, such as inconvenient feeding and discharging, low space utilization rate and difficult recovery of materials adhering to the wall.

[0016] Further, the steam explosion reaction cabin is integrated above with an electronic pressure detector for real-time monitoring of the internal pressure of the steam explosion reaction cabin, a temperature sensor for real-time monitoring of the internal temperature of the steam explosion reaction cabin and a quick pressure relief protection valve for emergency pressure relief in an extreme state, and a matched pneumatic pressure relief valve is used to realize instantaneous pressure relief, thereby forming a monitoring, control and protection closed loop and ensuring the safety and controllability of the reaction process.

[0017] The hard carbon material preparation method provided by the present application first electrically heats the steam explosion reaction cabin to above 100 DEG C to prevent steam condensation, solves the problem of insufficient local treatment caused by steam condensation and dripping after entering the steam explosion reaction cabin, then heats the water storage cabin to generate steam in-situ and maintain a set pressure, and finally realizes biomass wall breaking through instantaneous pressure relief by the pneumatic pressure relief valve. The present application utilizes the water in the biomass and the appropriate amount of water added to the water storage cabin, and makes the water directly vaporize to generate steam by using double heating devices, thereby realizing in-situ steam generation, reducing energy loss and condensation problems in steam transportation of traditional equipment.

[0018] Further, the water in the water storage tank is heated to 200-300 DEG C, the actual operating temperature and pressure of the application are higher, at a higher temperature, the water vapor can take away most of the inorganic salt, through electrochemical test, the biomass precursor obtained by the method provided by the application only needs to be dried, crushed and activated, and then hard carbon material can be obtained, the electrochemical performance of the hard carbon material can be similar to that of the precursor after acid washing treatment, and the hard carbon material can be directly used for coating of sodium ion batteries. The method of the application can directly perform subsequent battery preparation process, shorten production cycle, improve efficiency, save acid washing process, avoid generation and treatment of acid washing wastewater, reduce environmental pollution and save production cost.

[0019] Further, the application does not directly stack raw materials in the steam explosion reaction tank body, but puts the raw materials into a plurality of material baskets with air permeability, and lays the material baskets, so that the materials are laid and heated uniformly, the pretreatment effect is obvious. After the steam explosion reaction is completed, due to the existence of the material basket, the material almost does not exist with the water vapor together. The horizontal layout and the instantaneous pressure relief process reduce the extrusion and accumulation of biomass on the reaction kettle wall, effectively solve the technical problem that the biomass raw material is not uniformly heated and is caked on the reaction kettle wall during the reaction process. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A front view of an endogenous steam in-situ instantaneous expansion device provided by the application.

[0021] In the drawings: 1, steam explosion reaction tank body; 2, buffer tank; 3, feeding port; 4, quick opening blind plate; 5, air inlet valve; 6, quick pressure relief protection valve; 7, electronic pressure detector; 8, temperature sensor; 9, pneumatic pressure relief valve; 10, water storage tank; 11, circulating water pump; 12, pressure relief port. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the application clearer and more apparent, the application will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0023] As shown in the drawings, Figure 1 The endogenous steam in-situ instantaneous expansion device for preparing hard carbon material precursor for sodium ion battery in the embodiment includes a steam explosion reaction tank body 1, a buffer tank 2, a quick opening blind plate 4, an air inlet valve 5, a quick pressure relief protection valve 6, an electronic pressure detector 7, a temperature sensor 8, a pneumatic pressure relief valve 9, a water storage tank 10 and a circulating water pump 11.

[0024] The steam explosion reaction cabin 1 is horizontally placed, one side of the steam explosion reaction cabin 1 is provided with a feeding port 3, and the other side is provided with a pneumatic pressure relief valve 9, the pressure relief port 12 of the pneumatic pressure relief valve 9 is connected with the gas inlet of the buffer tank 2. When the steam explosion reaction cabin 1 needs to be relieved, the pneumatic pressure relief valve 9 is opened, and the excess gas in the steam explosion reaction cabin 1 is introduced into the buffer tank 2 for temporary storage. An electric heating device for auxiliary heating is arranged outside the steam explosion reaction cabin 1, a water storage cabin 10 is arranged below the steam explosion reaction cabin 1, the water storage cabin 10 is communicated with the steam explosion reaction cabin 1, and an air inlet valve 5 is arranged above the steam explosion reaction cabin 1, which is used to connect the gas cylinder for adjusting the reaction atmosphere.

[0025] The water storage cabin 10 below the steam explosion reaction cabin 1 is heated by an inductive heating device, which includes a heating jacket wrapped outside the water storage cabin 10. The core function is to transfer heat to the water storage cabin 10 by inductive heating, so that the water in the water storage cabin 10 is heated and vaporized to generate steam, which is an active heating component.

[0026] A jacket is arranged outside the heating jacket, the jacket is coaxially arranged with the heating jacket, and a cavity is formed between the heating jacket and the jacket. A circulating water pump 11 delivers cooling medium to the cavity through a pipeline, and the cooling medium circulates in the cavity to absorb excess heat transferred to the outer wall of the water storage cabin 10 during the operation of the inductive heating device, so as to avoid local overheating of the water storage cabin 10 and ensure uniform heating and vaporization of the water in the water storage cabin 10. The cooling medium is water.

[0027] An electronic pressure detector 7 is arranged above the steam explosion reaction cabin 1 for detecting the pressure inside the steam explosion reaction cabin 1.

[0028] A temperature sensor 8 is arranged above the steam explosion reaction cabin 1 for detecting the temperature inside the steam explosion reaction cabin 1.

[0029] A rapid pressure relief protection valve 6 is arranged above the steam explosion reaction cabin 1 for emergency pressure relief in a limit state.

[0030] Optionally, the steam explosion reaction cabin 1 is made of 316 stainless steel, and the structure is a full-welded structure, with a maximum use temperature of 300 DEG C and a maximum use pressure of 7.0 MPa.

[0031] Optionally, the feeding port 3 is a clamp type quick opening type, and a quick opening blind plate 4 is arranged above the feeding port 3, with a maximum use temperature of 300 DEG C and a pressure of 7.0 MPa.

[0032] A method for preparing hard carbon material from biomass includes the following steps: S1, open the quick-opening blind plate 4 at the feed inlet 3, inject water into the water storage tank 10 through the feed inlet 3 to meet the required amount, put the biomass into the material basket, then lay the material basket containing the biomass in a single layer in the steam explosion reaction cabin body 1, close the quick-opening blind plate 4 to ensure the sealing of the steam explosion reaction cabin body 1. If a specific gas atmosphere is required for the reaction, after closing the quick-opening blind plate 4, open the gas inlet valve 5 to introduce gas into the steam explosion reaction cabin body 1 to adjust the atmosphere, and close the gas inlet valve 5 after the adjustment is completed. The steam explosion reaction cabin body 1 is heated to above 100℃ by electric heating to prevent the water vapor rising into the steam explosion reaction cabin body 1 from condensing; when the set temperature is met, the electric heating device of the steam explosion reaction cabin body 1 is used for heat preservation; Wherein, the total water content in the raw material is obtained by the water content of the raw material and the mass of the raw material; after the reaction temperature and pressure are determined, there will be a saturated steam pressure in the closed space, and the total water amount required to generate saturated steam in the closed space can be calculated by the saturated steam pressure, and the calculation formula is: PV = nRT, wherein P is the pressure of water vapor, V is the sum of the volume of the steam explosion reaction cabin body 1 and the water storage tank 10, n is the amount of substance of water vapor, T represents the absolute temperature, and R represents the ideal gas constant. The total water amount required to generate saturated steam is subtracted from the total water content in the raw material to obtain the amount of exogenous water.

[0033] S2, the water in the water storage tank 10 is heated to a set temperature by the electric induction heating device, and a required amount of steam is generated, the steam enters the steam explosion reaction cabin body 1, and the temperature sensor 8 assists in monitoring the steam temperature in the steam explosion reaction cabin body 1 to ensure that it matches the heating temperature of the water storage tank 10; at the same time, the pressure in the steam explosion reaction cabin body 1 is maintained stable during the process; if the electronic pressure detector 7 shows that the pressure exceeds the safety threshold, such as close to 7.0 MPa, the rapid pressure relief protection valve 6 is automatically opened, and the emergency pressure relief is performed to the safety range to protect the safety of the steam explosion reaction cabin body 1; when the pressure returns to normal, the rapid pressure relief protection valve 6 is automatically closed. When the pressure holding reaches the set pressure holding time, the electric induction heating device of the water storage tank 10 is closed, and the pneumatic pressure relief valve 9 is opened to realize the instantaneous pressure relief of the inside of the steam explosion reaction cabin body 1, and the biomass is subjected to steam explosion to obtain a hard carbon material precursor. At this time, the high-pressure gas in the cabin is introduced into the buffer tank 2 through the pressure relief port 12 to avoid the safety hidden danger caused by direct discharge of the high-pressure gas, and the stable release of the pressure is realized. During the whole process of heating the water storage tank 10 by the electric induction heating device, the circulating water pump 11 is continuously operated to inject cooling water into the jacket to maintain the stable temperature of the heating jacket and ensure the uniform heating of the water storage tank 10. The set pressure holding time is 15-60 minutes.

[0034] Wherein, the electronic pressure detector 7 monitors the pressure in the steam explosion reaction cabin body 1 in real time, and when the pressure reaches the set value, the temperature rising of the electric induction heating device is stopped and the pressure holding stage is entered; the pressure is continuously monitored in the pressure holding stage, and if the pressure decreases, the intermittent heating pressure compensation is triggered.

[0035] S3, drying the hard carbon material precursor in an oven and crushing the hard carbon material precursor to obtain a crushed hard carbon material precursor, and activating the crushed hard carbon material precursor in an argon atmosphere to obtain the hard carbon material.

[0036] The activation temperature is 1100-1500°C, and the activation time is 15-60 minutes.

[0037] The hard carbon material can be directly used as a negative electrode material for sodium ion batteries in the coating process of the sodium ion batteries without the need for acid washing and other treatment steps, thereby saving the subsequent purification step, reducing the process complexity and cost of the battery production link, facilitating the large-scale application of sodium ion batteries, and avoiding the treatment cost and energy consumption of sewage after acid washing.

[0038] Example 1 The present embodiment provides a method for preparing a hard carbon material through endogenous steam instantaneous expansion, using bamboo as a raw material, comprising the following steps: First, open the quick-opening blind plate 4, add an appropriate amount of water to the water storage tank 10 through the feeding port 3, place the bamboo into the material frame, place the material frame into the steam explosion reaction cabin 1, and close the quick-opening blind plate 4, the air inlet valve 5, the quick pressure relief protection valve 6, and the pneumatic pressure relief valve 9, heat the steam explosion reaction cabin 1 to 180°C by means of electric heating and keep it at this temperature.

[0039] Heat the water in the water storage tank 10 to 240°C by means of an inductive heating device, and the electronic pressure detector 7 shows that the internal pressure of the steam explosion reaction cabin 1 is 3.5 Mpa. Keep it at this temperature for 45 min, then open the pneumatic pressure relief valve 9 to complete the pressure release to obtain the steam exploded bamboo, i.e. the hard carbon material precursor. Open the quick-opening blind plate 4 to take out all the steam exploded bamboo obtained by the reaction, collect and dry it. Activate the dried steam exploded bamboo at 1300°C in an argon atmosphere to obtain the activated hard carbon material. Coat the activated hard carbon material to obtain the negative electrode of the sodium ion battery, then assemble the sodium ion battery and test its performance. The final electrochemical performance of the sodium ion battery is: the capacity is 400 mAh / g, the first coulombic efficiency is 84%, and the reversible capacity is 336 mAh / g.

[0040] Example 2 The present embodiment provides a method for preparing a hard carbon material through endogenous steam instantaneous expansion, using grapevines as a raw material, comprising the following steps: First, open the quick-opening blind plate 4, add an appropriate amount of water to the water storage tank 10 through the feeding port 3, place the grapevines into the material frame, place the material frame into the steam explosion reaction cabin 1, and close the quick-opening blind plate 4, the air inlet valve 5, the quick pressure relief protection valve 6, and the pneumatic pressure relief valve 9, heat the steam explosion reaction cabin 1 to 180°C by means of electric heating and keep it at this temperature.

[0041] The water in the water storage tank 10 is heated to 220℃ by an inductive heating device, and the electronic pressure detector 7 shows that the internal pressure of the steam explosion reaction cabin 1 is 2.2Mpa. The temperature is maintained for 30min, and then the pneumatic pressure relief valve 9 is opened to complete the pressure release to obtain the steam exploded grapevine, i.e. the hard carbon material precursor. The fast-opening blind plate 4 is opened to take out all the steam exploded grapevines obtained by reaction, which are collected and dried. The dried steam exploded grapevines are activated at 1500℃ in an argon atmosphere to obtain activated hard carbon materials. The activated hard carbon materials are coated to obtain sodium ion battery anodes, and then the sodium ion battery is assembled and the performance is tested. The final electrochemical performance of the sodium ion battery is: the capacity is 346mAh / g, the first coulombic efficiency is 82%, and the reversible capacity is 283mAh / g.

[0042] Example 3 The present embodiment provides a method for preparing hard carbon materials by endogenous steam instantaneous expansion, using furfural residue as raw material, comprising the following steps: First, the fast-opening blind plate 4 is opened, and an appropriate amount of water is added to the water storage tank 10 through the feeding port 3. The furfural residue is placed in the material frame, the material frame is placed in the steam explosion reaction cabin 1, and the fast-opening blind plate 4, the air inlet valve 5, the rapid pressure relief protection valve 6 and the pneumatic pressure relief valve 9 are closed. The steam explosion reaction cabin 1 is heated to 180℃ by electric heating and kept at this temperature.

[0043] The water in the water storage tank 10 is heated to 200℃ by an inductive heating device, and the electronic pressure detector 7 shows that the internal pressure of the steam explosion reaction cabin 1 is 1.8Mpa. The temperature is maintained for 60min, and then the pneumatic pressure relief valve 9 is opened to complete the pressure release to obtain the steam exploded furfural residue, i.e. the hard carbon material precursor. The fast-opening blind plate 4 is opened to take out all the steam exploded furfural residues obtained by reaction, which are collected and dried. The dried steam exploded furfural residues are activated at 1100℃ in an argon atmosphere to obtain activated hard carbon materials. The activated hard carbon materials are coated to obtain sodium ion battery anodes, and then the sodium ion battery is assembled and the performance is tested. The final electrochemical performance of the sodium ion battery is: the capacity is 334mAh / g, the first coulombic efficiency is 86%, and the reversible capacity is 287mAh / g.

[0044] Example 4 The present embodiment provides a method for preparing hard carbon materials by endogenous steam instantaneous expansion, using xylitol residue as raw material, comprising the following steps: First, the fast-opening blind plate 4 is opened, and an appropriate amount of water is added to the water storage tank 10 through the feeding port 3. The furfural residue is placed in the material frame, the material frame is placed in the steam explosion reaction cabin 1, and the fast-opening blind plate 4, the air inlet valve 5, the rapid pressure relief protection valve 6 and the pneumatic pressure relief valve 9 are closed. The steam explosion reaction cabin 1 is heated to 180℃ by electric heating and kept at this temperature.

[0045] The water in the water storage tank 10 is heated to 300°C by an inductive heating device, and the electronic pressure detector 7 shows that the internal pressure of the steam explosion reaction cabin 1 is 6.8 Mpa. The temperature is maintained for 15 min, and then the pneumatic pressure relief valve 9 is opened to complete the pressure release to obtain the steam-exploded xylitol residue, i.e. the hard carbon material precursor. The steam-exploded xylitol residue obtained by the reaction is taken out through the quick-opening blind plate 4, collected and dried. The dried steam-exploded xylitol residue is activated at 1300°C in an argon atmosphere to obtain activated hard carbon material. The activated hard carbon material is coated to obtain a sodium ion battery negative electrode, and then a sodium ion battery is assembled and the performance is tested. The final electrochemical performance of the sodium ion battery is: the capacity is 418 mAh / g, the first coulombic efficiency is 83%, and the reversible capacity is 346 mAh / g.

[0046] Example 5 The present embodiment provides a method for preparing hard carbon material by endogenous steam instantaneous expansion, using coffee grounds as raw material, comprising the following steps: First, the quick-opening blind plate 4 is opened, and an appropriate amount of water is added to the water storage tank 10 through the feed inlet 3. The coffee grounds are placed in the material frame, the material frame is placed in the steam explosion reaction cabin 1, and the quick-opening blind plate 4, the air inlet valve 5, the quick pressure relief protection valve 6 and the pneumatic pressure relief valve 9 are closed. The steam explosion reaction cabin 1 is heated to 180°C by electric heating and kept at this temperature.

[0047] The water in the water storage tank 10 is heated to 240°C by an inductive heating device, and the electronic pressure detector 7 shows that the internal pressure of the steam explosion reaction cabin 1 is 3.5 Mpa. The temperature is maintained for 15 min, and then the pneumatic pressure relief valve 9 is opened to complete the pressure release to obtain the steam-exploded coffee residue, i.e. the hard carbon material precursor. The steam-exploded coffee residue obtained by the reaction is taken out through the quick-opening blind plate 4, collected and dried. The dried steam-exploded coffee residue is activated at 1300°C in an argon atmosphere to obtain activated hard carbon material. The activated hard carbon material is coated to obtain a sodium ion battery negative electrode, and then a sodium ion battery is assembled and the performance is tested. The final electrochemical performance of the sodium ion battery is: the capacity is 366 mAh / g, the first coulombic efficiency is 80%, and the reversible capacity is 292 mAh / g.

[0048] The above-mentioned examples use natural biomass such as bamboo and grapevines, and industrial / life waste such as furfural residue, xylitol residue and coffee grounds as raw materials, covering different types of biomass, which shows that the endogenous steam in-situ instantaneous expansion device has wide substrate adaptability and can process multiple types of biomass raw materials. Moreover, it does not need to make substantial process parameter adjustments due to differences in raw materials, effectively breaking through the limitations of traditional processes on the types of raw materials.

[0049] As can be known from the above examples, the hard carbon material obtained by the application can be directly used for coating of sodium ion batteries, to obtain a sodium ion battery negative electrode, and through adjustment of different biomasses and process parameters, the battery assembled by using the sodium ion battery negative electrode can stably achieve an electrochemical performance of a capacity of 334-418 mAh / g and a first coulomb efficiency of 86%, meeting the basic requirements of sodium ion batteries for negative electrode materials. The hard carbon material prepared by the pre-activation pore-forming and high-temperature carbonization process disclosed in the Chinese patent with the publication number CN112645305A has a reversible capacity of the sodium ion battery of 254.4 mAh / g and a first coulomb efficiency of 80% when used as a negative electrode of a sodium ion battery, and compared with the application, the application has a significant advantage in capacity and first coulomb efficiency.

[0050] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. An in situ, endogenous steam flash expansion device, comprising: It comprises a steam explosion reaction cabin (1), a buffer tank (2) and a water storage cabin (10), the steam explosion reaction cabin (1) is provided with a feeding port (3) on one side and a pneumatic pressure relief valve (9) on the other side, is externally provided with an electric heating device, and is provided below with the water storage cabin (10); the pressure relief port (12) of the pneumatic pressure relief valve (9) is communicated with the buffer tank (2); the water storage cabin (10) is communicated with the steam explosion reaction cabin (1), the water storage cabin (10) is externally provided with an electric induction heating device, and the electric induction heating device is externally provided with a jacket for accommodating a cooling medium.

2. An in-situ endogenous vapor flash expansion device according to claim 1, wherein, The steam explosion reaction cabin (1) is horizontally placed.

3. An in-situ endogenous vapor flash expansion device according to claim 1, wherein, The feeding port (3) is provided with a quick-opening blind plate (4).

4. The in-situ endogenous vapor flash expansion device of claim 1, wherein, The steam explosion reaction cabin (1) is provided above with a quick pressure relief protection valve (6), and is provided therein with an electronic pressure detector (7) for detecting the internal pressure of the steam explosion reaction cabin (1) and a temperature sensor (8) for detecting the internal temperature of the steam explosion reaction cabin (1).

5. An in-situ endogenous vapor flash expansion device according to claim 1, wherein, The steam explosion reaction cabin (1) adopts a through-welding structure.

6. An in situ endogenous vapor flash expansion device according to claim 1, wherein, The jacket is connected with a circulating water pump (11) through a pipeline.

7. An in-situ endogenous vapor flash expansion device according to claim 1, wherein, The steam explosion reaction cabin (1) is provided above with an air inlet valve (5) for connecting a gas bottle for adjusting the reaction atmosphere.

8. A method for preparing a hard carbon material, based on the in-situ instantaneous expansion device of endogenous steam according to any one of claims 1-7, characterized in that, It comprises the following steps: Water required for preparing hard carbon material is injected into the water storage cabin (10) through the feeding port (3), biomass is put into a material basket, and a plurality of the material baskets are placed in the steam explosion reaction cabin (1), and the steam explosion reaction cabin (1) is heated to above 100℃ by the electric heating device; The water in the water storage cabin (10) is heated to a required temperature by the electric induction heating device to generate a required amount of steam, and then pressure is maintained; when the pressure maintaining time reaches a set pressure maintaining time, the pneumatic pressure relief valve (9) is opened to realize instantaneous pressure relief in the steam explosion reaction cabin (1), and a hard carbon material precursor is obtained; The hard carbon material precursor is dried and crushed to obtain a crushed hard carbon material precursor, and the crushed hard carbon material precursor is activated under an inert gas atmosphere to obtain a hard carbon material.

9. The method of claim 8, wherein the hard carbon material is prepared by a process comprising: The water in the water storage cabin (10) is heated to 200-300℃ by the electric induction heating device.

10. The method of claim 8, wherein the hard carbon material is prepared by a process comprising: The material baskets are laid in a single layer in the steam explosion reaction cabin (1). The material baskets are laid in a single layer in the steam explosion reaction cabin (1).

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