Special-shaped high-temperature alkali metal heat pipe for cooling graphitization furnace

Abstract

The invention discloses a special-shaped high-temperature alkali metal heat pipe for cooling a graphitization furnace. The special-shaped high-temperature alkali metal heat pipe comprises a main lifting lug, a liquid filling pipe protection sleeve, an auxiliary lifting lug, a lifting lug connecting column, a liquid filling pipe, an end cover, a heat pipe wall, a liquid suction core, an alkali metal working medium, a spiral fin and a conical end cover. The device is complete in design, simple in structure and complete in function, and the problem that a high-temperature heat pipe is difficult to insert into a graphite heat preservation material is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy batteries, and particularly to a heterogeneous high-temperature alkali metal heat pipe for cooling a graphitization furnace. Background Art

[0002] Graphite materials have become the main materials for the negative electrodes of new energy lithium batteries on the market due to their high electrical conductivity, stability, and relatively low cost. The anisotropy of natural graphite particles may cause large volume expansion during charge and discharge, affecting the cycle life. Currently, this problem is usually solved by high-temperature polarization in an Acheson Graphitization Furnace. At high temperatures, the amorphous carbon or microcrystalline carbon in the carbon material gradually transforms into graphite crystals with a hexagonal crystal system structure. During this process, carbon atoms are rearranged, impurities and defects are eliminated, the lattice order is improved, the interlayer electron migration ability is enhanced, the resistivity is reduced, and the electrical conductivity is increased. However, due to the too low thermal conductivity of the graphite insulating material, the graphite after high-temperature polarization remains at a high temperature for a long time and cannot be cooled, which has become the most important factor restricting the production of graphite negative electrodes. Summary of the Invention

[0003] In order to cool the high-temperature graphite furnace insulating material with a dense texture after high-temperature polarization, accelerate the production of graphite negative electrodes, reduce energy consumption, and increase energy utilization efficiency, the purpose of the present invention is to provide a heterogeneous high-temperature alkali metal heat pipe for cooling a graphitization furnace, which uses the high heat transfer ability of the heat pipe to forcibly cool the graphite insulating material, can effectively complete the forced heat exchange of the graphite furnace, reduces the cooling time of the graphite after polarization, and can successfully avoid the difficulty of inserting the high-temperature heat pipe due to the too dense graphite insulating material. The structure is simple and reliable.

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

[0005] A special-shaped high-temperature alkali metal heat pipe for cooling a graphitization furnace, comprising a main lifting lug 1, a liquid filling pipe protective sleeve 2, a secondary lifting lug 3, a lifting lug connecting column 4, a liquid filling pipe 5, an end cover 6, a heat pipe wall 7, a wick 8, an alkali metal working fluid 9, spiral fins 10 and a conical end cover 11; the liquid filling pipe 5, the end cover 6, the heat pipe wall 7, the wick 8, the alkali metal working fluid 9, and the conical end cover 11 form a complete high-temperature alkali metal heat pipe body; the main lifting lug 1, the liquid filling pipe protective sleeve 2, the secondary lifting lug 3, the lifting lug connecting column 4, and the spiral fins 10 cooperate with the high-temperature alkali metal heat pipe body to achieve a morphological transformation design for facilitating the cooling of the graphitization furnace; the end cover 6 and the conical end cover 11 are respectively connected to the ends of the condensation section and the evaporation section of the heat pipe wall 7; the wick 8 is located inside the heat pipe wall 7 and closely adheres to the heat pipe wall 7; the spiral fins 10 are arranged axially along the evaporation section of the heat pipe wall 7; the liquid filling pipe 5 penetrates through the end cover 6 and is sealed; the liquid filling pipe protective sleeve 2 is welded to the outer surface of the end cover 6 and completely surrounds the liquid filling pipe 5; the main lifting lug 1 is fixedly connected to the liquid filling pipe protective sleeve 2; the lifting lug connecting column 4 is fixedly connected to the end cover 6, and the secondary lifting lug 3 is fixedly connected to the lifting lug connecting column 4.

[0006] The liquid filling pipe 5, the end cover 6, the heat pipe wall 7, and the conical end cover 11 are made of 316L or 310S stainless steel materials; the end cover 6 and the conical end cover 11 are respectively connected to the heat pipe wall 7 by argon arc welding; the thickness of the heat pipe wall 7 is not less than 5 mm; the end cover 6 is in the form of a double-layer concentric cylinder, the diameter of the lower end is slightly smaller than the inner diameter of the heat pipe wall 7, the diameter of the upper end is greater than or equal to the outer diameter of the heat pipe wall 7, the maximum thickness is not less than 20 mm, and the exposed outer side surface has indentations and protrusions to cooperate with the bayonet of an axial-rotation asynchronous motor; the apex angle of the conical end cover 11 is selected from different specifications such as 45° or 60° according to the actual site, and the inside is a conical cavity to store the high-temperature alkali metal working fluid and prevent the internal heat accumulation and melting of the conical end cover 11; to simultaneously meet the strength requirements and heat transfer requirements, the wall thickness of the conical end cover 11 should be greater than 5 mm and less than 15 mm.

[0007] The wick 8 is made of multiple layers of stainless steel wire mesh rolled up, and should have internal support to prevent collapse during use and the layers are connected by spot welding, and the wick 8 closely adheres to the heat pipe wall 7 through internal support; the alkali metal working fluid 9 usually adopts materials such as sodium, potassium, and lithium with a purity of 99%.

[0008] The liquid filling pipe 5 penetrates through the end cover 6 and is connected by argon arc welding at the interface. After the production of the high-temperature alkali metal heat pipe body is completed, the liquid filling pipe 5 should be compacted and welded off for complete sealing; the liquid filling pipe protective sleeve 2 is a cylindrical stainless steel pipe, welded to the outer surface of the end cover 6 and completely surrounding the liquid filling pipe 5; the inner diameter of the liquid filling pipe protective sleeve 2 should be 2 - 3 times the outer diameter of the liquid filling pipe 5, and the length of the liquid filling pipe protective sleeve 2 should be more than 15 mm longer than the length of the liquid filling pipe 5 exposed outside the end cover 6.

[0009] The main lifting lug 1 is a solid stainless steel ring with a diameter of not less than 8 mm and an inner ring diameter of not less than 40 mm, and is connected to the liquid-filled pipe protective sleeve 2 by welding; there should be indentations or protrusions inside the inner ring of the main lifting lug 1 to facilitate hanging, and the indentations or protrusions shall not affect the strength of the main lifting lug 1; the strength of the main lifting lug 1 itself and the welding strength between the main lifting lug 1 and the liquid-filled pipe protective sleeve 2 shall meet the load-bearing capacity of more than 70 kg.

[0010] The auxiliary lifting lug 3 is a solid stainless steel ring with a diameter of not less than 4 mm and an inner ring diameter of not less than 20 mm; the lug connecting column 4 is a cylindrical solid stainless steel, and part of the upper surface has a circular indentation to cooperate with the auxiliary lifting lug 3 to achieve the largest possible contact area; the auxiliary lifting lug (3) and the lug connecting column 4 are connected by welding, and the strength of the auxiliary lifting lug 3 itself and the welding strength between the auxiliary lifting lug 3 and the lug connecting column 4 shall meet the load-bearing capacity of more than 20 kg; the lug connecting columns 4 are distributed symmetrically or in an equilateral triangle on the end cover 6 and are connected by welding, and the welding strength between the lug connecting column 4 and the end cover 6 shall meet the load-bearing capacity of more than 20 kg and the lateral load-bearing capacity of more than 200 N; there are indentations or protrusions on the side surface of the lug connecting column 4 to facilitate lateral force application.

[0011] The spiral fin 10 is a stainless steel spiral fin with an arc-shaped cross-section, welded at the root on the heat pipe wall 7, with a width of more than 50 mm, occupying more than 30% of the total length of the heat pipe along the axial direction of the heat pipe, and the lowest end reaches the vertex of the conical end cover 11, and the inclination angle is selected between 15° and 30° in combination with the compactness of the specific graphite furnace insulation material and the torque of the rotating motor.

[0012] Compared with the prior art, the present invention has the following advantages:

[0013] The present invention uses a high-temperature alkali metal heat pipe as a cooling device, utilizes the characteristic of axial heat conduction of the heat pipe to export the accumulated heat in the graphite furnace insulation material, effectively reduces the heat dissipation difficulty caused by the poor heat conduction ability of the graphite furnace insulation material, greatly improves the production efficiency of the graphite negative electrode material, and at the same time, the directional heat conduction of the high-temperature heat pipe provides a prerequisite for waste heat utilization. The spiral fins of the heat pipe can increase the heat exchange area while assisting the heat pipe to screw into the dense insulation material layer along the axial direction, so as to avoid the increase in the compactness of the insulation material layer due to the insertion of multiple heat pipes, making it difficult to insert new heat pipes continuously, and meeting the simultaneous operation of a large number of heat pipes.

[0014] The present invention provides a relatively perfect design scheme for the special-shaped high-temperature alkali metal heat pipe for cooling the graphitization furnace. The structure of the present invention is compact and reliable, considering the difficulties faced in the actual use of the heat pipe. A feasible solution is provided for the problem of cooling the graphitization furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a front view of the special-shaped high-temperature alkali metal heat pipe for cooling the graphitization furnace. Detailed implementation mode

[0016] The present invention will be further described in conjunction with examples and drawings:

[0017] As shown in Figure 1 the figure, the heterogeneous high-temperature alkali metal heat pipe of the cooling graphitization furnace of the present invention includes a main lifting lug 1, a liquid filling pipe protective sleeve 2, a secondary lifting lug 3, a lifting lug connecting column 4, a liquid filling pipe 5, an end cover 6, a heat pipe wall 7, a wick 8, an alkali metal working medium 9, a spiral fin 10 and a conical end cover 11; the liquid filling pipe 5, the end cover 6, the heat pipe wall 7, the wick 8, the alkali metal working medium 9, and the conical end cover 11 form a complete high-temperature alkali metal heat pipe body; the main lifting lug 1, the liquid filling pipe protective sleeve 2, the secondary lifting lug 3, the lifting lug connecting column 4, and the spiral fin 10 cooperate with the high-temperature alkali metal heat pipe body to realize a morphological transformation design scheme for facilitating the cooling graphitization furnace.

[0018] As a preferred implementation mode of the present invention, the liquid filling pipe 5, the end cover 6, the heat pipe wall 7, and the conical end cover 11 are made of 316L or 310S stainless steel materials, which can reduce costs while meeting the requirements of high temperature resistance and corrosion resistance, and have good strength at high temperatures so that the shape of this heat pipe does not change; the end cover 6 and the conical end cover 11 are respectively connected to the heat pipe wall 7 by argon arc welding; the thickness of the heat pipe wall 7 is not less than 5 mm to ensure that the heat pipe does not break during operation; the shape of the end cover 6 is a double-layer concentric cylinder, the diameter of the lower end is slightly smaller than the inner diameter of the heat pipe wall 7, the diameter of the upper end is greater than or equal to the outer diameter of the heat pipe wall 7, and the maximum thickness is not less than 20 mm to prevent breakage caused by small weaknesses due to welding. At the same time, the larger thickness can provide a firm base for connecting other equipment at the top of the heat pipe, and the exposed side surface has dents and protrusions to cooperate with the bayonet of the axial rotating asynchronous motor; the apex angle of the conical end cover 11 is selected from different specifications such as 45° or 60° according to the actual site, and the inside is a conical cavity to store the high-temperature alkali metal working medium to prevent the internal heat accumulation of the conical end cover 11 from melting; to meet the strength requirements and heat transfer requirements at the same time, the wall thickness of the conical end cover 11 should be greater than 5 mm and less than 15 mm.

[0019] As a preferred implementation mode of the present invention, the wick 8 is made of multiple layers of stainless steel wire mesh rolled up. To prevent collapse during use, it should have internal support and be connected layer by layer by spot welding. The wick 8 is closely attached to the heat pipe wall 7 through internal support; the alkali metal working medium 9 usually adopts materials such as sodium, potassium, and lithium with a purity of 99%. The evaporation temperature of the alkali metal working medium matches the internal temperature of the graphite furnace. The high-temperature heat pipe filled with alkali metal can work at a high heat transfer efficiency for a long time in the graphite furnace. The compatibility of alkali metal with 316L and 310S is good, which prolongs the service life of the high-temperature heat pipe.

[0020] As a preferred embodiment of the present invention, the liquid filling tube 5 passes through the end cover 6 and is connected at the interface using argon arc welding. After the production of the high-temperature alkali metal heat pipe body is completed, the liquid filling tube 5 should be completely sealed by multiple sections of compaction welding. This operation ensures a high vacuum state inside the heat pipe, increases the starting length of the heat pipe, and improves the heat transfer efficiency; the liquid filling tube protective cover 2 is a cylindrical stainless steel tube, welded to the outer surface of the end cover 6 and completely surrounds the liquid filling tube 5; the inner diameter of the liquid filling tube protective cover 2 should be 2-3 times the outer diameter of the liquid filling tube 5, and the length of the liquid filling tube protective cover 2 should be more than 15 mm greater than the length of the liquid filling tube 5 exposed outside the end cover 6. The presence of the protective cover prevents damage to the liquid filling tube due to irregular operation, and also facilitates the placement of other equipment on the top of the heat pipe.

[0021] As a preferred embodiment of the present invention, the main lifting ear 1 is a solid stainless steel ring with a diameter of not less than 8 mm and an inner diameter of not less than 40 mm, which is connected to the liquid-filling tube protective cover 2 by welding; the inner ring of the main lifting ear 1 should have a dent or protrusion to facilitate hanging, and the dent or protrusion must not affect the strength of the main lifting ear 1; the strength of the main lifting ear 1 itself and the welding strength between the main lifting ear 1 and the liquid-filling tube protective cover 2 must meet the load-bearing capacity of more than 70 kg.

[0022] As a preferred embodiment of the present invention, the auxiliary lifting ear 3 is a solid stainless steel ring with a diameter of not less than 4 mm and an inner diameter of not less than 20 mm; the lifting ear connecting column 4 is a cylindrical solid stainless steel, and the annular indentation on the upper surface cooperates with the auxiliary lifting ear 3 to achieve the largest possible contact area; the auxiliary lifting ear (3) and the lifting ear connecting column 4 are connected by welding, and the strength of the auxiliary lifting ear 3 itself and the welding strength between the auxiliary lifting ear 3 and the lifting ear connecting column 4 must meet the load-bearing capacity of more than 20 kg to prevent the heat pipe from accidentally falling off and causing damage and causing accidents; the lifting ear connecting column 4 is distributed symmetrically or in an equilateral triangle on the end cover 6, so that the heat pipe does not tilt when it is lifted, and at the same time, it is evenly stressed to prevent a single lifting ear 3 from falling off. It is connected by welding, and the welding strength of the lifting ear connecting column 4 and the end cover 6 should meet the load-bearing capacity of more than 20 kg and the lateral load of more than 200 N to withstand the force applied by the motor when the heat pipe is rotated and inserted into the graphite; the side surface of the lifting ear connecting column 4 has indentations or protrusions to facilitate lateral force application.

[0023] As a preferred embodiment of the present invention, the spiral fin 10 is a stainless steel spiral fin with an arc-shaped cross-section, welded to the heat pipe wall 7 at the root, with a width of more than 50 mm, occupying more than 30% of the total length of the heat pipe along the axial direction of the heat pipe. During the process of inserting into the graphite furnace, the dense graphite powder hinders the insertion of the heat pipe. The graphite powder at the center of the furnace body is removed by rotating through the spiral fin 10, thereby reducing the axial reaction force received by the top of the heat pipe, ensuring that the entire evaporation section of the heat pipe is completely in a high-temperature environment, improving the starting length and working temperature of the heat pipe, and enhancing the heat transfer efficiency. The lowest end reaches the vertex of the conical end cap 11. The inclination angle is selected between 15° and 30° in combination with the density of the specific graphite furnace insulation material and the torque of the rotating motor. An excessively low inclination angle will result in too short fin spacing and a large torque required for rotation; while an excessively large inclination angle can carry out less graphite powder and is difficult to insert downward.

[0024] The working principle of the present invention is as follows: The evaporation section of the high-temperature heat pipe absorbs heat in the graphite furnace insulation material, and through the phase change of the internal alkali metal working fluid 9, the heat is transferred to the top condensation section, and the heat is transferred from the inside of the insulation material layer to the environment through measures such as natural cooling or forced convection. With the assistance of the externally added rotating motor, the spiral fin 10 and the conical end cap 11, the heat pipe body can be smoothly rotated into the dense insulation material. During the rotation process, the insulation material moves to the surface along the spiral fin 10, thus avoiding continuous compaction and making it possible to cool a large number of heat pipes simultaneously. The indentations and protrusions of the end cap 6 and the lug connection column 4 facilitate the cooperation of the device with the gripper of the rotating motor and prevent slipping during rotation. The main lug 1 and the secondary lug 3 cooperate with the hanging cable suspended above the heat pipe to be used for lateral movement or to prevent accidental detachment of the heat pipe.

Claims

1. A heterogeneous high-temperature alkali metal heat pipe for cooling a graphitization furnace, characterized in that: It includes a main lifting lug (1), a liquid filling pipe protective sleeve (2), a secondary lifting lug (3), a lifting lug connecting column (4), a liquid filling pipe (5), an end cover (6), a heat pipe wall (7), a wick (8), an alkali metal working medium (9), spiral fins (10) and a conical end cover (11); the liquid filling pipe (5), the end cover (6), the heat pipe wall (7), the wick (8), the alkali metal working medium (9), and the conical end cover (11) form a complete high-temperature alkali metal heat pipe body; the main lifting lug (1), the liquid filling pipe protective sleeve (2), the secondary lifting lug (3), the lifting lug connecting column (4), and the spiral fins (10) cooperate with the high-temperature alkali metal heat pipe body to realize a morphological transformation design for facilitating the cooling of the graphitization furnace; the end cover (6) and the conical end cover (11) are respectively connected to the ends of the condensation section and the evaporation section of the heat pipe wall (7); the wick (8) is located inside the heat pipe wall (7) and closely adheres to the heat pipe wall (7); the spiral fins (10) are arranged axially along the evaporation section of the heat pipe wall (7); the liquid filling pipe (5) penetrates through the end cover (6) and is sealed; the liquid filling pipe protective sleeve (2) is welded to the outer surface of the end cover (6) and completely surrounds the liquid filling pipe (5); the main lifting lug (1) is fixedly connected to the liquid filling pipe protective sleeve (2); the lifting lug connecting column (4) is fixedly connected to the end cover (6), and the secondary lifting lug (3) is fixedly connected to the lifting lug connecting column (4).

2. The heterogeneous high-temperature alkali metal heat pipe for a cooling graphitization furnace according to claim 1, characterized in that: The liquid filling pipe (5), the end cover (6), the heat pipe wall (7), and the conical end cover (11) are made of 316L or 310S stainless steel materials; the end cover (6) and the conical end cover (11) are respectively connected to the heat pipe wall (7) by argon arc welding; the thickness of the heat pipe wall (7) is not less than 5 mm; the end cover (6) is in the form of a double-layer concentric cylinder, the diameter of the lower end is smaller than the inner diameter of the heat pipe wall (7), the diameter of the upper end is larger than or equal to the outer diameter of the heat pipe wall (7), the maximum thickness is not less than 20 mm, and the exposed outer side surface has indentations and protrusions to cooperate with the bayonet of the axial rotation asynchronous motor; the apex angle of the conical end cover (11) is selected from 45° or 60° of different specifications according to the actual site, and the inside is a conical cavity to store the high-temperature alkali metal working medium to prevent the internal heat accumulation and melting of the conical end cover (11); to simultaneously meet the strength requirements and heat transfer requirements, the wall thickness of the conical end cover (11) should be greater than 5 mm and less than 15 mm.

3. The heterogeneous high-temperature alkali metal heat pipe for cooling a graphitization furnace according to claim 1, characterized in that: The wick (8) is made of multiple layers of stainless steel wire mesh rolled up. To prevent collapse during use, it should have internal support and the layers are connected by spot welding. The wick (8) closely adheres to the heat pipe wall (7) through internal support.

4. The heterogeneous high-temperature alkali metal heat pipe for cooling a graphitization furnace according to claim 1, characterized in that: The alkali metal working medium (9) adopts sodium, potassium, or lithium materials with a purity of 99%.

5. The heterogeneous high-temperature alkali metal heat pipe for cooling a graphitization furnace according to claim 1, characterized in that: The liquid filling pipe (5) penetrates through the end cover (6) and is connected by argon arc welding at the interface. After the production of the high-temperature alkali metal heat pipe body is completed, the liquid filling pipe (5) should be compacted and welded off for complete sealing; the liquid filling pipe protective sleeve (2) is a cylindrical stainless steel pipe, the inner diameter of the liquid filling pipe protective sleeve (2) should be 2 - 3 times the outer diameter of the liquid filling pipe (5), and the length of the liquid filling pipe protective sleeve (2) should be more than 15 mm longer than the length of the liquid filling pipe (5) exposed outside the end cover (6).

6. The heterogeneous high-temperature alkali metal heat pipe for a cooling graphitization furnace according to claim 1, characterized in that: The main lifting lug (1) is a solid stainless steel ring with a diameter of not less than 8 mm and an inner ring diameter of not less than 40 mm, and is connected to the liquid-filled pipe protective sleeve (2) by welding; there should be indentations or protrusions on the inner ring of the main lifting lug (1) to facilitate hanging, and the indentations or protrusions shall not affect the strength of the main lifting lug (1); the strength of the main lifting lug (1) itself and the welding strength between the main lifting lug (1) and the liquid-filled pipe protective sleeve (2) shall meet the load-bearing capacity of more than 70 kg.

7. The heterogeneous high-temperature alkali metal heat pipe for cooling a graphitization furnace according to claim 1, wherein: The auxiliary lifting lug (3) is a solid stainless steel ring with a diameter of not less than 4 mm and an inner ring diameter of not less than 20 mm; the lug connecting column (4) is a cylindrical solid stainless steel, and there are partial annular indentations on the upper surface to cooperate with the auxiliary lifting lug (3) to achieve the largest possible contact area; the auxiliary lifting lug (3) and the lug connecting column (4) are connected by welding, and the strength of the auxiliary lifting lug (3) itself and the welding strength between the auxiliary lifting lug (3) and the lug connecting column (4) shall meet the load-bearing capacity of more than 20 kg; the lug connecting columns (4) are distributed symmetrically or in an equilateral triangle on the end cover (6) and are connected by welding, and the welding strength between the lug connecting column (4) and the end cover (6) shall meet the load-bearing capacity of more than 20 kg and the lateral load-bearing capacity of more than 200 N; there are indentations or protrusions on the side surface of the lug connecting column (4) to facilitate lateral force application.

8. The heterogeneous high-temperature alkali metal heat pipe for cooling a graphitization furnace according to claim 1, wherein: The spiral fin (10) is a stainless steel spiral sheet with an arc-shaped cross-section, the root of which is welded to the heat pipe wall (7), with a width of more than 50 mm, occupying more than 30% of the total length of the heat pipe along the axial direction of the heat pipe, and the lowest end reaches the vertex of the conical end cover (11). The inclination angle is selected between 15° and 30° in combination with the compactness of the specific graphite furnace thermal insulation material and the torque of the rotating motor.

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