High-temperature heat pipe enhanced cooling and waste heat energy gradient recycling system and method of graphitization furnace

Abstract

The invention discloses a high-temperature heat pipe enhanced cooling and waste heat energy gradient recycling system and method of a graphitization furnace. The system comprises a graphite furnace wall, a graphite heat preservation material, graphite, a high-temperature heat pipe, a fused salt heat exchange sleeve, a fused salt pipeline, a fused salt tank heat preservation layer, a heating wire, a fused salt tank, a high-temperature fused salt pump, a water tank, a water pipeline, a water pump, a power source and a water-fused salt heat exchanger. The fused salt heat exchange sleeve, the fused salt pipeline, the fused salt tank and the high-temperature fused salt pump form a fused salt loop; the water tank, the water pipeline, the water pump, the power supply and the water-molten salt heat exchanger form a water loop. The molten salt loop and the water loop are used for jointly completing the dual functions of cooling the graphite heat preservation material and utilizing waste heat; the device is complete in design, and is used for forcibly cooling the graphite furnace body subjected to high-temperature polarization and recycling and utilizing waste heat in the furnace.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery materials, and particularly relates to a high-temperature heat pipe enhanced cooling and waste heat energy cascade recovery and utilization system and method for a graphitization furnace. Background Art

[0002] The mainstream anode materials mainly include graphite-based, silicon-based and lithium titanate, etc. Among them, graphite-based materials dominate the market due to their high conductivity, stability and low cost. However, the anisotropy of natural graphite may cause volume expansion during charge and discharge, affecting the cycle life. At high temperatures, amorphous carbon or microcrystalline carbon in carbon materials will be transformed into hexagonal graphite crystals. This process eliminates impurities and defects through the rearrangement of carbon atoms, improves the lattice order degree, enhances the interlayer electron migration ability, thereby reducing the resistivity and increasing the conductivity. The Acheson graphitization furnace, as a traditional high-temperature heat treatment equipment, is widely used for the graphitization treatment of lithium battery anode materials. However, due to the low thermal conductivity of the materials and the insulating materials in the furnace, the insulating materials can only dissipate heat effectively on the surface layer, and the inside of the insulating materials is in a high-temperature state for a long time and cannot be cooled in time. The too long cooling cycle has become a bottleneck restricting the production efficiency of polarized graphite. Summary of the Invention

[0003] In order to solve the problems existing in the above-mentioned prior art, the object of the present invention is to propose a high-temperature heat pipe enhanced cooling and waste heat energy cascade recovery and utilization system and method for a graphitization furnace, to accelerate the completion of the insulating materials of the graphite furnace after high-temperature polarization and to effectively utilize the waste heat accumulated in the furnace.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A high-temperature heat pipe enhanced cooling and waste heat energy cascade recovery and utilization system for a graphitization furnace, comprising a graphite furnace wall 1, graphite insulating materials 2, graphite 3, high-temperature heat pipes 4, molten salt heat exchange sleeves 5, molten salt pipelines 6, molten salt tank insulation layers 7, heating wires 8, molten salt tanks 9, high-temperature molten salt pumps 10, water tanks 11, water pipelines 12, water pumps 13, power supplies 14 and water-molten salt heat exchangers 15; the graphite furnace wall 1, graphite insulating materials 2 and graphite 3 together form a complete graphitization furnace, the graphite 3 is placed at the bottom of the graphite furnace wall 1, the graphite insulating materials 2 completely wrap the graphite 3 and are piled up in large quantities above; the evaporation sections of the high-temperature heat pipes 4 are inserted into the graphite insulating materials 2 above the graphite 3, the molten salt heat exchange sleeves 5 are nested on the condensation sections of the high-temperature heat pipes 4, and are connected to the molten salt tanks 9 through the molten salt pipelines 6 to form a molten salt loop, and the high-temperature molten salt pumps 10 are used to maintain the molten salt circulation in the molten salt loop; the molten salt tanks 9 are wrapped with molten salt tank insulation layers 7, and heating wires 8 are arranged between the molten salt tanks 9 and the molten salt tank insulation layers 7; water-molten salt heat exchangers 15 are arranged in the molten salt tanks 9, and a water loop is formed with the external water tanks 11 through the water pipelines 12, and the water pumps 13 are used to maintain the water circulation in the water loop; the heating wires 8, high-temperature molten salt pumps 10 and water pumps 13 are powered by an external power supply 14.

[0006] The molten salt heat exchange jacket 5, the molten salt pipeline 6, the molten salt tank 9 and the high-temperature molten salt pump 10 form a molten salt loop; the water tank 11, the water pipeline 12, the water pump 13, the power supply 14 and the water-molten salt heat exchanger 15 form a water loop; the molten salt tank 9 is mainly made of corrosion-resistant and high-temperature-resistant metal materials such as 316L stainless steel, 310S stainless steel or nickel-based alloy, etc. There are openings at the bottom and top of the tank body for the molten salt in the circulation pipeline to enter and exit the tank body; the molten salt tank insulation layer 7 is mainly composed of an asbestos layer and is attached with an aluminum foil reflective layer on the outside, requiring the molten salt in the molten salt tank 9 to be maintained in a liquid state for a long time; the heating wire 8 is attached to the surface layer of the molten salt tank 9, requiring it to maintain heating at 800°C for a long time.

[0007] The graphite furnace wall 1 is a pool-type frame built with materials such as bricks and concrete. The graphite insulation material 2 is composed of materials such as coke and graphite, wrapping the graphite 3 at the bottom of the graphite furnace wall 1 and mainly piled above the graphite 3; the high-temperature heat pipe 4 is a high-temperature alkali metal heat pipe with sodium and potassium as representative working fluids, the pipe material is 310S stainless steel, and there is a hollow cone head at the bottom of the evaporation section of the heat pipe to smoothly enter the dense graphite insulation material 2.

[0008] The molten salt heat exchange jacket 5 is nested in the condensation section of the high-temperature heat pipe 4, with liquid molten salt flowing inside, absorbing heat at the condensation section and then being driven by the high-temperature and corrosion-resistant high-temperature molten salt pump 10 through the molten salt pipeline 6 to circulate to the molten salt tank 9; the molten salt heat exchange jacket 5 is rigidly sealed with the condensation section of the warm heat pipe 4 to prevent the overflow of high-temperature molten salt. The entire outer side of the molten salt pipeline 6 is wrapped with heat-insulating cotton and an aluminum foil reflective layer to ensure that the molten salt in the pipeline does not condense.

[0009] The water-molten salt heat exchanger 15 is placed in the molten salt tank 9, with circulating water flowing inside, being heated by the high-temperature molten salt in the molten salt tank 9 and then being driven by the water pump 13 through the water pipeline 12 to enter the water tank 11 to form a cycle; the place where the water pipeline 12 passes through the molten salt tank 9 is connected by high-temperature-resistant sealing. Fins are attached to the water-molten salt heat exchanger 15 to increase the heat exchange efficiency, and the water tank 11 is wrapped with heat-insulating cotton and an aluminum foil reflective layer for heat preservation inside the water tank.

[0010] The heating wire 8, the high-temperature molten salt pump 10 and the water pump 13 are powered by an external power supply 14; according to the facilities in the specific processing workshop, the sling is fixed at the top of the high-temperature heat pipe 4, and the vertical movement of the high-temperature heat pipe 4 is realized by using a gantry crane.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] The present invention uses the method of inserting high-temperature heat pipes into the graphite heat-insulating material. Through the forced cooling of the high-temperature heat pipes, the heat dissipation difficulty caused by low thermal conductivity is effectively solved. By utilizing the excellent heat transfer efficiency of the high-temperature heat pipes, the heat dissipation time after the polarization of the graphite furnace is greatly reduced. At the same time, the directional export of waste heat is realized, the waste heat utilization is effectively achieved, the production is accelerated, and the energy utilization rate can be effectively improved.

[0013] The present invention aims at the enhanced cooling of high-temperature heat pipes and the cascaded recovery and utilization of waste heat energy in a graphitization furnace, and proposes a system design scheme for verifying feasibility. The design scheme of the present invention is rigorous and complete. The idea of selecting high-temperature heat pipes reduces excessive external equipment, and at the same time improves production efficiency and energy utilization. Brief Description of the Drawings

[0014] Figure 1 It is a schematic diagram of the enhanced cooling of high-temperature heat pipes and the cascaded recovery and utilization of waste heat energy system for a graphitization furnace. Detailed Embodiments

[0015] The present invention will be further described in combination with examples and drawings:

[0016] As Figure 1 shown, the enhanced cooling of high-temperature heat pipes and the cascaded recovery and utilization of waste heat energy system of the graphitization furnace of the present invention includes a graphite furnace wall 1, a graphite heat-insulating material 2, graphite 3, high-temperature heat pipes 4, a molten salt heat exchange sleeve 5, a molten salt pipeline 6, a molten salt tank heat-insulating layer 7, a heating wire 8, a molten salt tank 9, a high-temperature molten salt pump 10, a water tank 11, a water pipeline 12, a water pump 13, a power supply 14, and a water-molten salt heat exchanger 15. The graphite furnace wall 1, the graphite heat-insulating material 2, and the graphite 3 together form a complete graphitization furnace. The graphite 3 is placed at the bottom of the graphite furnace wall 1. The graphite heat-insulating material 2 completely wraps the graphite 3 and accumulates in large quantities above it. The evaporation section of the high-temperature heat pipe 4 is inserted into the graphite heat-insulating material 2 above the graphite 3. The molten salt heat exchange sleeve 5 is nested on the condensation section of the high-temperature heat pipe 4 and is connected to the molten salt tank 9 through the molten salt pipeline 6 to form a molten salt loop, and the high-temperature molten salt pump 10 is used to maintain the molten salt circulation in the molten salt loop. The molten salt tank 9 is externally wrapped with a molten salt tank heat-insulating layer 7, and a heating wire 8 is arranged between the molten salt tank 9 and the molten salt tank heat-insulating layer 7. A water-molten salt heat exchanger 15 is arranged in the molten salt tank 9 and forms a water loop with an external water tank 11 through the water pipeline 12, and the water pump 13 is used to maintain the water circulation in the water loop. The heating wire 8, the high-temperature molten salt pump 10, and the water pump 13 are powered by an external power supply 14.

[0017] As a preferred embodiment of the present invention, the molten salt heat exchange jacket 5, the molten salt pipeline 6, the molten salt tank 9 and the high-temperature molten salt pump 10 form a molten salt loop; the water tank 11, the water pipeline 12, the water pump 13, the power supply 14 and the water-molten salt heat exchanger 15 form a water loop; the molten salt tank 9 is mainly made of corrosion-resistant and high-temperature-resistant metal materials such as 316L stainless steel, 310S stainless steel or nickel-based alloy, etc., and there are openings at the bottom and top of the tank body for the molten salt in the circulation pipeline to enter and exit the tank body; the molten salt tank insulation layer 7 is mainly composed of an asbestos layer and is attached with an aluminum foil reflective layer on the outside, and it is required to keep the molten salt in the molten salt tank 9 in a liquid state for a long time; the heating wire 8 is attached to the surface layer of the molten salt tank 9, and it is required to maintain heating at 800 °C for a long time. This solution can ensure that the molten salt remains in a liquid state for a long time to prevent blockage of the loop, and at the same time, the relatively high temperature can keep the heat exchange efficiency at a relatively high level.

[0018] As a preferred embodiment of the present invention, the graphite furnace wall 1 is a pool-type frame built with materials such as bricks and concrete. The graphite heat insulation material 2 is composed of materials such as coke and graphite, wraps the graphite 3 at the bottom of the graphite furnace wall 1, and is mainly piled up above the graphite 3; the high-temperature heat pipe 4 is a high-temperature alkali metal heat pipe using sodium and potassium as representative working fluids, the pipe material is 310S stainless steel, and the working temperature of the alkali metal working fluid fits the internal temperature of the graphite furnace. The high-temperature heat pipe filled with alkali metal can maintain long-term and effective heat exchange in the graphite furnace. The 310S stainless steel material has excellent corrosion resistance and high-temperature resistance, ensuring the long-term stable operation of the heat pipe; there is a hollow cone head at the bottom of the evaporation section of the heat pipe to facilitate smooth entry into the dense graphite heat insulation material 2.

[0019] As a preferred embodiment of the present invention, the molten salt heat exchange jacket 5 is nested in the condensation section of the high-temperature heat pipe 4, and liquid molten salt flows inside. After absorbing heat at the condensation section, it is driven by the high-temperature molten salt pump 10 with high temperature and corrosion resistance and circulates through the molten salt pipeline 6 to the molten salt tank 9; the molten salt heat exchange jacket 5 is rigidly sealed with the condensation section of the warm tube 4 to prevent high-temperature molten salt from overflowing. The entire outer side of the molten salt pipeline 6 is wrapped with heat insulation cotton and an aluminum foil reflective layer to ensure that the molten salt in the pipeline does not condense.

[0020] As a preferred embodiment of the present invention, the water-molten salt heat exchanger 15 is placed in the molten salt tank 9, and circulating water flows inside. After being heated by the high-temperature molten salt in the molten salt tank 9, it is driven by the water pump 13 and enters the water tank 11 through the water pipeline 12 to form a cycle; the place where the water pipeline 12 passes through the molten salt tank 9 is connected by high-temperature resistance sealing. Fins are attached to the water-molten salt heat exchanger 15 to increase the heat exchange efficiency, and the water tank 11 is wrapped with heat insulation cotton and an aluminum foil reflective layer for heat preservation inside the water tank.

[0021] As a preferred embodiment of the present invention, the heating wire 8, the high-temperature molten salt pump 10 and the water pump 13 are powered by an external power supply 14; according to the facilities in the specific processing workshop, the sling is fixed at the top of the high-temperature heat pipe 4, and the high-temperature heat pipe 4 is moved vertically by a gantry crane. The external power supply facilitates rapid power-off in case of an accident, and the layout at the top of the heat pipe can effectively prevent accidental falling. The external power supply 14 and the power supply of the heat pipe driving device need to be coordinated with the actual conditions of the production workshop.

[0022] The working principle of the present invention is as follows: After the graphite 3 is subjected to high-temperature polarization, the high-temperature heat pipe 4 is inserted into the high-temperature graphite insulating material 2. The graphite insulating material 2 heats the evaporation section of the high-temperature heat pipe, and the high-temperature heat pipe 4 starts. Driven by the high-temperature molten salt pump 10, the heated high-temperature molten salt in the molten salt heat exchange sleeve 5 enters the molten salt tank 9, and the low-temperature molten salt in the molten salt tank 9 flows to the molten salt heat exchange sleeve 5 to absorb the heat of the high-temperature heat pipe, thereby realizing the one-loop heat transfer of heat from the graphite insulating material 2 to the molten salt. In the water circuit, the water pump 13 is used to drive the water in the water tank 11 to flow through the water pipeline 12 and the water-molten salt heat exchanger 15 to continuously remove the heat inside the molten salt tank 9. The heating wire 8 is used to maintain the molten salt in the molten salt tank 9 in a liquid state for easy startup of the system. The molten salt tank insulation layer 7 and the water tank 11 with heat insulation effect reduce heat waste. The molten salt circuit and the water circuit together complete the dual functions of cooling the graphite insulating material 2 and utilizing waste heat.

Claims

1. A high-temperature heat pipe enhanced cooling and waste heat energy cascaded recovery and utilization system for a graphitization furnace, characterized in that: It includes a graphite furnace wall (1), graphite insulating material (2), graphite (3), high-temperature heat pipes (4), molten salt heat exchange sleeve (5), molten salt pipeline (6), molten salt tank insulation layer (7), heating wire (8), molten salt tank (9), high-temperature molten salt pump (10), water tank (11), water pipeline (12), water pump (13), power supply (14) and water - molten salt heat exchanger (15); the graphite furnace wall (1), graphite insulating material (2) and graphite (3) together form a complete graphitization furnace, the graphite (3) is placed at the bottom of the graphite furnace wall (1), the graphite insulating material (2) completely wraps the graphite (3) and accumulates in large quantities above it; the evaporation section of the high-temperature heat pipe (4) is inserted into the graphite insulating material (2) above the graphite (3), the molten salt heat exchange sleeve (5) is nested on the condensation section of the high-temperature heat pipe (4), and is connected to the molten salt tank (9) through the molten salt pipeline (6) to form a molten salt loop, and the high-temperature molten salt pump (10) is used to maintain the molten salt circulation in the molten salt loop; the outside of the molten salt tank (9) is wrapped with a molten salt tank insulation layer (7), and heating wires (8) are arranged between the molten salt tank (9) and the molten salt tank insulation layer (7); a water - molten salt heat exchanger (15) is arranged in the molten salt tank (9), and a water loop is formed with an external water tank (11) through the water pipeline (12), and the water pump (13) is used to maintain the water circulation in the water loop; the heating wire (8), high-temperature molten salt pump (10) and water pump (13) are powered by an external power supply (14).

2. The high-temperature heat pipe enhanced cooling and waste heat energy cascade recycling system of a graphitization furnace according to claim 1, wherein: The molten salt heat exchange sleeve (5), molten salt pipeline (6), molten salt tank (9) and high-temperature molten salt pump (10) form a molten salt loop; the water tank (11), water pipeline (12), water pump (13), power supply (14) and water - molten salt heat exchanger (15) form a water loop; the molten salt tank (9) has a main body made of a corrosion-resistant and high-temperature-resistant metal material, and the metal material is selected from 316L stainless steel, 310S stainless steel or nickel-based alloy. There are openings at the bottom and top of the tank body for the molten salt in the circulation pipeline to enter and exit the tank body; the molten salt tank insulation layer (7) is mainly composed of an asbestos layer and is attached with an aluminum foil reflective layer on the outside, and it is required to keep the molten salt in the molten salt tank (9) in a liquid state for a long time; the heating wire (8) is attached to the surface layer of the molten salt tank (9), and it is required to maintain heating at 800 °C for a long time.

3. A high-temperature heat pipe enhanced cooling and waste heat energy cascade recovery and utilization system for a graphitization furnace according to claim 1, characterized in that: The graphite furnace wall (1) is a pool-type frame built with brick and concrete materials, and the graphite insulating material (2) is composed of coke and graphite materials, wraps the graphite (3) at the bottom of the graphite furnace wall (1), and mainly accumulates above the graphite (3).

4. A high-temperature heat pipe enhanced cooling and waste heat energy cascade recovery and utilization system for a graphitization furnace according to claim 1, characterized in that: The high-temperature heat pipe (4) is a high-temperature alkali metal heat pipe using sodium and potassium as representative working fluids, the pipe material is 310S stainless steel, and there is a hollow cone head at the bottom of the evaporation section of the heat pipe to facilitate smooth entry into the dense graphite insulating material (2).

5. A high-temperature heat pipe enhanced cooling and waste heat energy cascade recovery and utilization system for a graphitization furnace according to claim 1, characterized in that: The molten salt heat exchange sleeve (5) is nested on the condensation section of the high-temperature heat pipe (4), with liquid molten salt flowing inside, absorbing heat at the condensation section and then being driven by the high-temperature and corrosion-resistant high-temperature molten salt pump (10) to circulate through the molten salt pipeline (6) to the molten salt tank (9); the molten salt heat exchange sleeve (5) is rigidly sealed with the condensation section of the high-temperature heat pipe (4) to prevent the overflow of high-temperature molten salt, and the entire section of the molten salt pipeline (6) is wrapped with heat-insulating cotton and an aluminum foil reflective layer to ensure that the molten salt in the pipeline does not condense.

6. A high-temperature heat pipe enhanced cooling and waste heat energy cascade recovery and utilization system for a graphitization furnace according to claim 1, characterized in that: The water-salt heat exchanger (15) is placed in the molten salt tank (9), with circulating water flowing inside. After being heated by the high-temperature molten salt in the molten salt tank (9), it is driven by the water pump (13) and enters the water tank (11) through the water pipeline (12) to form a cycle. The part where the water pipeline (12) passes through the molten salt tank (9) is connected by a high-temperature resistant seal. Fins are attached to the water-salt heat exchanger (15) to increase the heat exchange efficiency. The water tank (11) is wrapped with heat insulation cotton and an aluminum foil reflective layer for heat preservation inside the tank.

7. A high-temperature heat pipe enhanced cooling and waste heat energy cascade recovery and utilization system for a graphitization furnace according to claim 1, characterized in that: The heating wire (8), the high-temperature molten salt pump (10) and the water pump (13) are powered by an external power supply (14). According to the facilities in the specific processing workshop, the sling is fixed at the top of the high-temperature heat pipe (4), and the high-temperature heat pipe (4) is moved vertically by using a gantry crane.

8. The working method of the high-temperature heat pipe enhanced cooling and waste heat energy cascade recovery and utilization system of the graphitization furnace according to any one of claims 1 to 7, characterized in that: After the graphite (3) is subjected to high-temperature polarization, the high-temperature heat pipe (4) is inserted into the high-temperature graphite heat preservation material (2). The graphite heat preservation material (2) heats the evaporation section of the high-temperature heat pipe, and the high-temperature heat pipe (4) starts. Driven by the high-temperature molten salt pump (10), the heated high-temperature molten salt in the molten salt heat exchange sleeve (5) enters the molten salt tank (9). The low-temperature molten salt in the molten salt tank (9) flows to the molten salt heat exchange sleeve (5) to absorb the heat of the high-temperature heat pipe, thereby realizing the one-way heat transfer of heat from the graphite heat preservation material (2) to the molten salt. In the water circuit, the water pump (13) is used to drive the water in the water tank (11) to flow through the water pipeline (12) and the water-salt heat exchanger (15), continuously taking away the heat inside the molten salt tank (9). The heating wire (8) is used to keep the molten salt in the molten salt tank (9) in a liquid state for easy startup of the system. The molten salt tank insulation layer (7) and the water tank (11) with heat preservation effect reduce heat waste. The molten salt circuit and the water circuit jointly complete the dual functions of cooling the graphite heat preservation material (2) and utilizing waste heat.

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