System and method for producing coal-based hard carbon by a coke oven

Abstract

The application provides a system and method for preparing coal-based hard carbon by a coke oven, and the system comprises a pre-oxidation section, a high-temperature carbonization section and a cooling section. The pre-oxidation section is internally provided with a first oven cavity, and the first oven cavity is provided with a feeding port, a first discharging port, an air inlet and a water vapor inlet. The water vapor inlet is connected with a high-temperature steam generator, and the first oven cavity is provided with a first heating device. The high-temperature carbonization section is internally provided with a second oven cavity, and the second oven cavity is connected with the first oven cavity through the first discharging port. The second oven cavity is provided with a nitrogen inlet, a urea inlet and a second discharging port, and the second oven cavity is provided with a second heating device. The cooling section is internally provided with a third oven cavity, and the third oven cavity is connected with the second oven cavity through the second discharging port. The third oven cavity is provided with a cooling device, and the third oven cavity is provided with a third discharging port. The application can improve the lithium storage capacity or sodium storage capacity of the prepared coal-based hard carbon, so that the prepared coal-based hard carbon can be applied to lithium batteries or sodium batteries as a negative electrode material.

Description

Technical Field

[0001] This invention relates to the field of hard carbon material preparation, and more particularly to a system and method for preparing coal-based hard carbon in a coke oven. Background Technology

[0002] Hard carbon materials are commonly used to prepare anode materials for lithium-ion and sodium-ion batteries. The preparation of hard carbon materials requires the selection of suitable precursors and high-temperature carbonization. Commonly used precursors include resins, biomass, and pitch. Using coal as a precursor is uncommon. While coal is cheap, readily available, and has a high carbon yield, its inherent properties mean that direct carbonization results in soft carbon materials, leading to lower lithium-ion or sodium-ion battery storage capacities. Summary of the Invention

[0003] The present invention aims to at least partially solve one of the technical problems in the related art. To this end, the embodiments of the present invention provide a system for preparing coal-based hard carbon in a coking oven. The coal-based hard carbon finally prepared is used as a negative electrode material in lithium batteries or sodium batteries, which can improve the lithium storage capacity or sodium storage capacity of lithium batteries or sodium batteries.

[0004] This invention also provides a method for preparing coal-based hard carbon in a coking oven.

[0005] This invention also provides a coal-based hard carbon prepared using the above-described method.

[0006] This invention also provides an application of the above-mentioned coal-based hard carbon in the preparation of negative electrode materials for lithium batteries or sodium batteries.

[0007] The system for preparing coal-based hard carbon in a coking oven according to an embodiment of the present invention includes: a pre-oxidation section, a high-temperature carbonization section, and a cooling section. The pre-oxidation section has a first furnace cavity, which has a feed inlet, a first discharge outlet, an air inlet, and a steam inlet. The steam inlet is connected to a high-temperature steam generator. Coal powder is supplied into the first furnace cavity through the feed inlet, and air and steam required for oxidizing the coal powder are supplied into the first furnace cavity through the air inlet and the steam inlet, respectively. The first furnace cavity is equipped with a first heating device to heat and oxidize the coal powder, and the oxidized coal powder is discharged through the first discharge outlet.

[0008] The high-temperature carbonization section has a second furnace chamber, which is connected to the first furnace chamber through a first discharge port. The second furnace chamber has a nitrogen inlet, a urea inlet, and a second discharge port. Nitrogen and urea required for the high-temperature carbonization reaction are introduced into the second furnace chamber through the nitrogen inlet and the urea inlet. The second furnace chamber is equipped with a second heating device to carry out the high-temperature carbonization reaction of the oxidized coal powder and discharge the obtained nitrogen-doped coal-based hard carbon material from the second discharge port.

[0009] The cooling section has a third furnace chamber, which is connected to the second furnace chamber through a second discharge port. The third furnace chamber is equipped with a cooling device to cool the nitrogen-doped coal-based hard carbon material. The third furnace chamber has a third discharge port to discharge the cooled nitrogen-doped coal-based hard carbon material through the third discharge port.

[0010] This application improves the lithium or sodium storage capacity of the prepared coal-based hard carbon by setting a pre-oxidation section and a high-temperature carbonization section in the coking oven. This allows the prepared coal-based hard carbon to be used as a negative electrode material in lithium batteries or sodium batteries, thereby improving the lithium or sodium storage capacity of lithium batteries or sodium batteries.

[0011] This application introduces a water vapor inlet in the pre-oxidation section and introduces water vapor during the oxidation process, which helps coal powder form more abundant pores and improves the lithium or sodium storage capacity of the final hard carbon product.

[0012] This application introduces nitrogen gas into the high-temperature carbonization section, allowing nitrogen to be passed through during the carbonization process. This process effectively increases the lithium or sodium storage capacity of coal-based hard carbon and improves its electrical conductivity. Furthermore, since the high-temperature carbonization reaction requires an air-isolated environment, the introduction of nitrogen provides an oxygen-free environment for the high-temperature carbonization section.

[0013] In some embodiments, the system for preparing coal-based hard carbon in a coke oven further includes a silo and a grinding unit. The silo has a silo outlet, which is connected to a feed inlet via a feed pipe. The grinding unit is connected to a branch pipe, which is connected in parallel with the feed pipe between the silo outlet and the feed inlet.

[0014] The branch pipeline has a branch inlet and a branch outlet. The branch pipeline is connected to the feed pipe through the branch inlet and the branch outlet respectively. The branch inlet is near the silo outlet and the branch outlet is near the feed inlet, so as to transport the lumpy coal in the silo to the grinding unit for grinding, and transport the pulverized coal obtained after grinding to the feed inlet of the pre-oxidation section.

[0015] This application uses a grinding unit to grind coal into coal powder of a certain particle size, so that the oxidation reaction in the pre-oxidation section and the high-temperature carbonization reaction in the high-temperature carbonization section are more complete.

[0016] In some embodiments, the grinding unit includes: a grinding mill, an acid washing tank, a drying chamber, and a coal powder storage silo. The grinding mill is connected to the outlet of the silo to grind lumpy coal into coal powder. The acid washing tank is connected to the grinding mill to acid wash the coal powder. The drying chamber is connected to the acid washing tank to dry the acid-washed coal powder. The coal powder storage silo has an inlet and an outlet. The inlet is connected to the drying chamber to store the dried coal powder, and the outlet is connected to the feed inlet of the pre-oxidation section. The grinding mill, acid washing tank, drying chamber, and coal powder storage silo are connected sequentially along the branch inlet toward the branch outlet.

[0017] In some embodiments, the system for preparing coal-based hard carbon in a coke oven further includes a secondary combustion furnace, wherein the first furnace chamber has a first pyrolysis gas outlet, the second furnace chamber has a second pyrolysis gas outlet, and the first pyrolysis gas outlet and the second pyrolysis gas outlet are connected together to the secondary combustion furnace to return the pyrolysis gas discharged from the first furnace chamber and the second furnace chamber to the furnace for combustion.

[0018] This application utilizes a secondary combustion furnace to burn the pyrolysis gas discharged from the pre-oxidation section and the high-temperature carbonization section, thereby making rational use of the pyrolysis gas.

[0019] In some embodiments, the system for preparing coal-based hard carbon in a coke oven further includes a heat exchanger having a tube-side inlet, a tube-side outlet, and a shell-side inlet. The tube-side inlet is connected to a cooling device, and the tube-side outlet is connected to a high-temperature steam generator. The secondary combustion furnace has a hot gas outlet connected to the shell-side inlet to exchange heat between the warm water discharged from the cooling device and the hot gas in the heat exchanger. The hot water generated after the heat exchange is then fed into the high-temperature steam generator to generate steam.

[0020] This application utilizes a heat exchanger to heat the warm water discharged from the cooling device by using the heat generated by the secondary combustion furnace, thus avoiding heat waste and improving energy efficiency.

[0021] In some embodiments, both the first heating device and the second heating device include a microwave heating device and an external heating device. This can increase the heating rate in the pre-oxidation section and the high-temperature carbonization section, resulting in more uniform heating of the material.

[0022] The method for preparing coal-based hard carbon in a coking oven according to an embodiment of the present invention uses the above-described system for preparing coal-based hard carbon in a coking oven, and includes the following steps: coal powder is introduced into a first furnace chamber for an oxidation reaction; air and steam are introduced into the first furnace chamber and the coal powder is heated to obtain oxidized coal powder; the oxidized coal powder is introduced into a second furnace chamber for a high-temperature carbonization reaction; nitrogen and urea are introduced into the second furnace chamber and the oxidized coal powder is heated to obtain nitrogen-doped coal-based hard carbon material; the nitrogen-doped coal-based hard carbon material is introduced into a third furnace chamber for cooling treatment.

[0023] This application involves pre-oxidizing coal powder followed by high-temperature carbonization to prepare coal-based hard carbon, which can be used as a negative electrode material in lithium batteries or sodium batteries to improve the lithium storage capacity or sodium storage capacity of lithium batteries or sodium batteries.

[0024] This application introduces nitrogen gas into the high-temperature carbonization section to dope coal-based hard carbon with nitrogen during the high-temperature carbonization reaction, which can effectively improve the lithium storage capacity or sodium storage capacity of coal-based hard carbon and enhance its electrical conductivity.

[0025] In some embodiments, the system for preparing coal-based hard carbon in a coke oven further includes a secondary combustion furnace and a heat exchanger. The pyrolysis gas generated in the first and second furnace chambers is fed into the secondary combustion furnace for combustion. The resulting hot gas is fed into the heat exchanger to exchange heat with the warm water discharged from the cooling device. The resulting hot water is fed into a high-temperature steam generator to generate steam. The steam is fed into the first furnace chamber to participate in the oxidation reaction of pulverized coal.

[0026] The present invention also provides a coal-based hard carbon prepared using the above method.

[0027] This invention also provides an application of coal-based hard carbon in the preparation of negative electrode materials for lithium-ion or sodium-ion batteries. Using the prepared coal-based hard carbon as a negative electrode material in lithium-ion or sodium-ion batteries can improve the lithium storage capacity or sodium storage capacity of the batteries. Attached Figure Description

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings.

[0029] in:

[0030] Figure 1 This is a schematic diagram of the system for preparing coal-based hard carbon using a coke oven, as described in this application embodiment.

[0031] Figure label:

[0032] 1-Blouse; 2-Feed pipe; 3-Branch pipe; 4-Grinding mill; 5-Powdered coal storage silo; 6-Acid washing tank; 7-Drying chamber; 8-Pre-oxidation section; 9-High-temperature carbonization section; 10-Cooling device; 11-Cooling section; 12-Storage silo; 13-High-temperature steam generator; 14-Secondary combustion furnace; 15-Heat exchanger. Detailed Implementation

[0033] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0034] The following describes a system for preparing coal-based hard carbon using a coke oven according to an embodiment of the present invention, with reference to the accompanying drawings.

[0035] like Figure 1As shown, one embodiment of this application proposes a system for preparing coal-based hard carbon in a coking oven, comprising: a pre-oxidation section 8, a high-temperature carbonization section 9, and a cooling section 11. The pre-oxidation section 8 has a first furnace cavity, which has a feed inlet, a first discharge outlet, an air inlet, and a steam inlet. The steam inlet is connected to a high-temperature steam generator 13. Coal powder is supplied to the first furnace cavity through the feed inlet, and air and steam required for oxidizing the coal powder are supplied to the first furnace cavity through the air inlet and the steam inlet, respectively. The first furnace cavity is equipped with a first heating device to heat and oxidize the coal powder, and the oxidized coal powder is discharged through the first discharge outlet.

[0036] The high-temperature carbonization section 9 has a second furnace chamber, which is connected to the first furnace chamber through a first discharge port. The second furnace chamber has a nitrogen inlet, a urea inlet, and a second discharge port. Nitrogen and urea required for the high-temperature carbonization reaction are introduced into the second furnace chamber through the nitrogen inlet and the urea inlet. The second furnace chamber is equipped with a second heating device to carry out the high-temperature carbonization reaction of the oxidized coal powder and discharge the obtained nitrogen-doped coal-based hard carbon material from the second discharge port.

[0037] The cooling section 11 has a third furnace chamber, which is connected to the second furnace chamber through the second discharge port. The third furnace chamber is equipped with a cooling device 10 to cool down the nitrogen-doped coal-based hard carbon material. The third furnace chamber has a third discharge port to discharge the cooled nitrogen-doped coal-based hard carbon material through the third discharge port.

[0038] This application improves the lithium or sodium storage capacity of the prepared coal-based hard carbon by setting a pre-oxidation section 8 and a high-temperature carbonization section 9 in the coking oven, so that the prepared coal-based hard carbon can be used as a negative electrode material in lithium batteries or sodium batteries, thereby improving the lithium or sodium storage capacity of lithium batteries or sodium batteries.

[0039] This application introduces a water vapor inlet in the pre-oxidation section 8 and introduces water vapor during the oxidation process, which is beneficial for the coal powder to form more abundant pores and improves the lithium or sodium storage capacity of the final hard carbon product.

[0040] This application introduces nitrogen into the high-temperature carbonization section 9 by setting a nitrogen inlet and introducing nitrogen during the carbonization process. This process effectively improves the lithium or sodium storage capacity of the coal-based hard carbon and enhances its electrical conductivity. Furthermore, since the high-temperature carbonization reaction requires an air-isolated environment, introducing nitrogen provides an oxygen-free environment for the high-temperature carbonization section 9.

[0041] Furthermore, the cooling device 10 is specifically a cooling water device. The cooling water device includes a cooling water coil located in the third furnace chamber, through which cooling water flows.

[0042] In some embodiments, the system for preparing coal-based hard carbon in a coke oven according to this application further includes a silo 1 and a grinding unit. The silo 1 has a silo 1 outlet, and the silo 1 outlet is connected to the feed inlet through a feed pipe 2. The grinding unit is connected to a branch pipe 3, and the branch pipe 3 and the feed pipe 2 are connected in parallel between the silo 1 outlet and the feed inlet.

[0043] Branch pipe 3 has a branch inlet and a branch outlet. Branch pipe 3 is connected to feed pipe 2 through the branch inlet and the branch outlet respectively. The branch inlet is near the outlet of silo 1 and the branch outlet is near the feed inlet, so as to transport the lumpy coal in silo 1 to the grinding unit for grinding and transport the pulverized coal obtained after grinding to the feed inlet of pre-oxidation section 8.

[0044] This application uses a grinding unit to grind coal into coal powder of a certain particle size, so that the oxidation reaction in the pre-oxidation section 8 and the high-temperature carbonization reaction in the high-temperature carbonization section 9 are more complete.

[0045] In some embodiments, the grinding unit includes: a grinding mill 4, an acid washing tank 6, a drying chamber 7, and a coal powder storage silo 5. The grinding mill 4 is connected to the outlet of the silo 1 to grind lumpy coal into coal powder. The acid washing tank 6 is connected to the grinding mill 4 to acid wash the coal powder. The drying chamber 7 is connected to the acid washing tank 6 to dry the acid-washed coal powder. The coal powder storage silo 5 has an inlet and an outlet. The inlet is connected to the drying chamber 7 to store the dried coal powder, and the outlet is connected to the feed inlet of the pre-oxidation section 8. The grinding mill 4, the acid washing tank 6, the drying chamber 7, and the coal powder storage silo 5 are connected sequentially along the branch inlet toward the branch outlet.

[0046] Furthermore, a first control valve is connected to the feed pipe 2 between the branch inlet and the branch outlet, and a second control valve is connected to the connecting pipe between the mill 4 and the branch inlet to switch the direction of the raw material coming out of the silo 1. When the coal in the silo 1 is not in powder form, the first control valve needs to be disconnected and the second control valve connected, so that the coal is ground into pulverized coal before being fed into the pre-oxidation section 8. When the coal in the silo 1 is already in powder form, the second control valve needs to be disconnected and the first control valve connected, so that the pulverized coal is directly fed into the pre-oxidation section 8.

[0047] In some embodiments, the system for preparing coal-based hard carbon in a coke oven according to this application further includes a secondary combustion furnace 14, a first furnace chamber having a first pyrolysis gas outlet, a second furnace chamber having a second pyrolysis gas outlet, and the first pyrolysis gas outlet and the second pyrolysis gas outlet being connected together to the secondary combustion furnace 14 to return the pyrolysis gas discharged from the first furnace chamber and the second furnace chamber to the furnace for combustion.

[0048] This application utilizes a secondary combustion furnace 14 to burn the pyrolysis gas discharged from the pre-oxidation section 8 and the high-temperature carbonization section 9, thereby making reasonable use of the pyrolysis gas.

[0049] Furthermore, the secondary combustion furnace 14 also has an air supplement port for supplying the air required for combustion into the secondary combustion furnace 14.

[0050] In some embodiments, the system for preparing coal-based hard carbon in a coke oven according to this application further includes a heat exchanger 15. The heat exchanger 15 has a tube-side inlet, a tube-side outlet, and a shell-side inlet. The tube-side inlet is connected to a cooling device 10, and the tube-side outlet is connected to a high-temperature steam generator 13. The secondary combustion furnace 14 has a hot gas outlet, which is connected to the shell-side inlet to exchange heat between the warm water discharged from the cooling device 10 and the hot gas in the heat exchanger 15. The hot water generated after the heat exchange is introduced into the high-temperature steam generator 13 to generate steam.

[0051] Furthermore, the heat exchanger 15 also has a shell-side outlet, which is connected to the flue to discharge the heat-exchanged exhaust gas to the power plant flue.

[0052] This application uses a heat exchanger 15 to heat the warm water discharged from the cooling device 10 by utilizing the heat generated by the secondary combustion furnace 14, which avoids heat waste and improves energy utilization efficiency.

[0053] In some embodiments, both the first heating device and the second heating device include a microwave heating device and an external heating device. This can increase the heating rate in the pre-oxidation section 8 and the high-temperature carbonization section 9, resulting in more uniform heating of the material.

[0054] In some embodiments, a blower is connected to the air inlet to introduce air into the first furnace chamber, so that the pulverized coal in the furnace is fully pre-oxidized.

[0055] In some embodiments, the first furnace chamber, the second furnace chamber, and the third furnace chamber are all large-capacity furnace chambers, capable of producing large quantities of nitrogen-doped coal-based hard carbon materials at once.

[0056] Another embodiment of this application provides a method for preparing coal-based hard carbon using a coke oven. The system for preparing coal-based hard carbon using the above-mentioned coke oven includes the following steps: pulverized coal is fed into the first furnace chamber of the pre-oxidation section 8 for oxidation reaction; air and steam are introduced into the first furnace chamber to heat the pulverized coal, resulting in oxidized pulverized coal; the oxidized pulverized coal is fed into the second furnace chamber of the high-temperature carbonization section 9 for high-temperature carbonization reaction; nitrogen and urea are introduced into the second furnace chamber to heat the oxidized pulverized coal, resulting in nitrogen-doped coal-based hard carbon material; the nitrogen-doped coal-based hard carbon material is fed into the third furnace chamber of the cooling section 11 for cooling treatment.

[0057] This application involves pre-oxidizing coal powder followed by high-temperature carbonization to prepare coal-based hard carbon, which can be used as a negative electrode material in lithium batteries or sodium batteries to improve the lithium storage capacity or sodium storage capacity of lithium batteries or sodium batteries.

[0058] This application introduces nitrogen gas into the high-temperature carbonization section 9 to dope coal-based hard carbon during the high-temperature carbonization reaction, which can effectively improve the lithium storage capacity or sodium storage capacity of coal-based hard carbon and enhance its electrical conductivity.

[0059] In some embodiments, the oxidation temperature in the pre-oxidation section 8 is 2-4 hours, preferably 3 hours.

[0060] In some embodiments, the carbonization temperature in the high-temperature carbonization section 9 is 1200-1600°C.

[0061] In some embodiments, the carbonization time in the high-temperature carbonization section 9 is 2-4 hours, preferably 3 hours.

[0062] In some embodiments, the system for preparing coal-based hard carbon in a coke oven further includes a secondary combustion furnace 14 and a heat exchanger 15. The pyrolysis gas generated in the first furnace chamber and the second furnace chamber is fed into the secondary combustion furnace 14 for combustion. The resulting hot gas is fed into the heat exchanger 15 to exchange heat with the warm water discharged from the cooling device 10. The resulting hot water is fed into the high-temperature steam generator 13 to generate steam. The steam is fed into the first furnace chamber to participate in the oxidation reaction of pulverized coal.

[0063] The present invention also provides a coal-based hard carbon prepared using the above method.

[0064] This invention also provides an application of coal-based hard carbon in the preparation of negative electrode materials for lithium-ion or sodium-ion batteries. Using the prepared coal-based hard carbon as a negative electrode material in lithium-ion or sodium-ion batteries can improve the lithium storage capacity or sodium storage capacity of the batteries.

[0065] The present application will be further illustrated by specific embodiments below.

[0066] Example 1

[0067] like Figure 1 As shown, a method for preparing coal-based hard carbon in a coke oven includes the following steps:

[0068] S1, the coal in the silo 1 is fed into the grinding mill 4 and ground into coal powder of a certain particle size. Then it is sent to the pickling tank 6 for deashing and pickling treatment. After that, it is dried in the drying chamber 7 and the dried coal powder is stored in the coal powder storage silo 5.

[0069] S2, pulverized coal is introduced into the first furnace chamber of the pre-oxidation section 8 for oxidation reaction. Air and water vapor are introduced into the first furnace chamber to heat the pulverized coal. After 3 hours of oxidation, oxidized pulverized coal is obtained. The heating method adopts a combination of microwave heating device and external heating device.

[0070] S3, the oxidized coal powder is fed into the second furnace chamber of the high-temperature carbonization section 9 for high-temperature carbonization reaction. The carbonization temperature is 1500℃ and the carbonization time is 3 hours. Nitrogen and urea are introduced into the second furnace chamber and the oxidized coal powder is heated to obtain nitrogen-doped coal-based hard carbon material. The heating method adopts a combination of microwave heating device and external heating device.

[0071] S4, nitrogen-doped coal-based hard carbon material is introduced into the third furnace chamber of cooling section 11 for cooling treatment, and after cooling, it falls into storage silo 12 for storage.

[0072] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0073] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0074] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0075] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0076] In this invention, the term "some embodiments," etc., refers to specific features, structures, materials, or characteristics described in connection with that embodiment, which are included in at least one embodiment of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiments. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments. Moreover, those skilled in the art can combine and integrate the different embodiments described in this specification and the features of the different embodiments without contradiction.

[0077] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A system for preparing coal-based hard carbon in a coking oven, characterized in that, include: The pre-oxidation section has a first furnace cavity, which has a feed inlet, a first discharge outlet, an air inlet, and a steam inlet. The steam inlet is connected to a high-temperature steam generator. The first furnace cavity is equipped with a first heating device to heat and oxidize the pulverized coal, and the oxidized pulverized coal is discharged through the first discharge outlet. The high-temperature carbonization section has a second furnace chamber, which is connected to the first furnace chamber through the first discharge port. The second furnace chamber has a nitrogen inlet, a urea inlet and a second discharge port, and is equipped with a second heating device. The cooling section has a third furnace chamber, which is connected to the second furnace chamber through the second discharge port. The third furnace chamber is equipped with a cooling device and has a third discharge port.

2. The system for preparing coal-based hard carbon in a coke oven according to claim 1, characterized in that, It also includes a hopper and a grinding unit. The hopper has a hopper outlet, which is connected to the feed inlet via a feed pipe. The grinding unit is connected to a branch pipe, which is connected in parallel with the feed pipe between the hopper outlet and the feed inlet. The branch pipe has a branch inlet and a branch outlet, which are connected to the feed pipe via the branch inlet and the branch outlet, respectively. The branch inlet is adjacent to the hopper outlet, and the branch outlet is adjacent to the feed inlet.

3. The system for preparing coal-based hard carbon from a coking oven according to claim 2, characterized in that, The grinding unit includes: A grinding mill, wherein the grinding mill is connected to the outlet of the silo; A pickling tank, which is connected to the grinding mill; Drying chamber, the drying chamber being connected to the pickling tank; The pulverized coal storage silo has an inlet and an outlet. The inlet is connected to the drying chamber, and the outlet is connected to the feed inlet of the pre-oxidation section. The grinding mill, the pickling tank, the drying chamber, and the pulverized coal storage silo are connected sequentially along the branch inlet toward the branch outlet.

4. The system for preparing coal-based hard carbon in a coke oven according to claim 1, characterized in that, It also includes a secondary combustion furnace, wherein the first furnace chamber has a first pyrolysis gas outlet, the second furnace chamber has a second pyrolysis gas outlet, and the first pyrolysis gas outlet and the second pyrolysis gas outlet are connected to the secondary combustion furnace.

5. The system for preparing coal-based hard carbon in a coking oven according to claim 4, characterized in that, It also includes a heat exchanger having a tube-side inlet, a tube-side outlet and a shell-side inlet, the tube-side inlet being connected to the cooling device, the tube-side outlet being connected to the high-temperature steam generator, and the secondary combustion furnace having a hot gas outlet connected to the shell-side inlet.

6. The system for preparing coal-based hard carbon in a coke oven according to claim 1, characterized in that, Both the first heating device and the second heating device include a microwave heating device and an external heating device.

7. A method for preparing coal-based hard carbon in a coke oven, characterized in that, The system according to any one of claims 1-6 comprises the following steps: Powdered coal is introduced into the first furnace chamber for an oxidation reaction. Air and steam are introduced into the first furnace chamber and the powdered coal is heated to obtain oxidized powdered coal. The oxidized coal powder is introduced into the second furnace chamber for high-temperature carbonization reaction. Nitrogen and urea are introduced into the second furnace chamber and the oxidized coal powder is heated to obtain nitrogen-doped coal-based hard carbon material. The nitrogen-doped coal-based hard carbon material is introduced into the third furnace cavity for cooling.

8. The method for preparing coal-based hard carbon in a coking oven according to claim 7, characterized in that, The system for preparing coal-based hard carbon in the coke oven also includes a secondary combustion furnace and a heat exchanger. The pyrolysis gas generated in the first furnace chamber and the second furnace chamber is fed into the secondary combustion furnace for combustion. The resulting hot gas is fed into the heat exchanger to exchange heat with the warm water discharged from the cooling device. The resulting hot water is fed into the high-temperature steam generator to generate steam. The steam is fed into the first furnace chamber to participate in the oxidation reaction of pulverized coal.

9. A coal-based hard carbon prepared using the method of claim 7 or 8.

10. The application of the coal-based hard carbon of claim 9 in the preparation of negative electrode materials for lithium batteries or sodium batteries.

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