A heated intermediate packaging device

Abstract

This invention discloses a heatable tundish device, belonging to the field of metal powder preparation technology. To address the problem of easy clogging of existing nozzles, the heatable tundish device includes an upper tundish body (4) and a lower tundish body (33) arranged vertically. The upper tundish body (4) contains an upper shell (11), an upper electromagnetic induction layer, an upper graphite sleeve (31), and a riser (3). The upper induction coil (8) within the upper electromagnetic induction layer can electromagnetically heat the upper graphite sleeve (31). The lower tundish body (33) contains a lower shell (21), a lower electromagnetic induction layer, a lower graphite sleeve, and a lower flow channel. The lower induction coil (13) within the lower electromagnetic induction layer can electromagnetically heat the lower graphite sleeve. The heatable tundish device can continuously raise the temperature, with the tundish temperature reaching ≥1500℃, solving the problem of a large temperature difference between the molten steel and the tundish, and avoiding the risk of clogging of the atomization nozzle.

Description

Technical Field

[0001] This invention relates to the field of metal powder preparation technology, specifically a heated intermediate ladle device. Background Technology

[0002] In vacuum tight-coupled gas atomization technology, the atomization process requires melting in a large crucible, then pouring the molten metal into a small tundish. The molten metal then flows through the tundish into a guide nozzle, and is finally atomized into fine powder by high-pressure gas ejected from the spray plate. After the molten metal (such as steel) flows out of the nozzle, it comes into full contact with the high-pressure inert gas. At the moment of contact, the ratio of molten steel to gas must be carefully considered. If the ratio is too high, the molten steel will flow out relatively quickly, meaning a larger amount of molten steel flows out per unit time. This may cause the molten steel temperature to become too high, significantly increasing the material burn-off and leading to product quality abnormalities. It may also produce some black particles. If the ratio is too low, the molten steel is likely to not flow completely out of the nozzle, causing molten steel to clump and blockage at the nozzle, significantly increasing the atomization risk. Once the nozzle becomes blocked, it not only greatly reduces the efficiency of the atomization production process, but more seriously, it leads to the waste of a batch of raw metal, making subsequent processing difficult.

[0003] The root cause of molten steel failing to flow due to nozzle blockage is that the nozzle temperature in the tundish system is too low. The molten metal cools rapidly after entering the tundish system, eventually causing solidification and blockage at the minimum diameter of the nozzle. To solve this problem, experienced operators typically slightly increase the superheat of the molten steel to improve its fluidity and prevent nozzle blockage. Currently, there is limited research on the structural design and insulation capabilities of tundish units, resulting in a persistently low temperature in the tundish while the temperature of the molten steel in the crucible remains high. This significant temperature difference causes a substantial drop in the temperature of the molten steel in the crucible. Ultimately, the only solution is to use small nozzles for high melting temperatures or relatively large nozzles for low temperatures to ensure successful atomization. However, this reduces the yield of fine powder, increases costs significantly and makes them uncontrollable. Furthermore, the stability of the tundish unit is relatively poor, often leading to the risk of steel leakage during heating, increasing material costs. It also cannot effectively filter alloys containing impurities, causing these impurities to enter the nozzles, causing blockage and halting atomization. Summary of the Invention

[0004] To address the problem of easy clogging of the aforementioned leak nozzles, this invention provides a heatable tundish device. The heatable tundish device can continuously raise the temperature, and the temperature of the tundish can be raised to ≥1500℃, solving the problem of large temperature difference between molten steel and tundish and avoiding the risk of clogging of atomized leak nozzles.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A heatable intermediate package device includes an upper package body and a lower package body arranged vertically. The upper package body contains an upper shell, an upper electromagnetic induction layer, an upper graphite sleeve, and a riser, which are sequentially arranged horizontally from the outside to the inside. The upper electromagnetic induction layer contains an upper induction coil, which can electromagnetically heat the upper graphite sleeve. The lower package body contains a lower shell, a lower electromagnetic induction layer, a lower graphite sleeve, and a lower flow channel, which are sequentially arranged horizontally from the outside to the inside. The lower electromagnetic induction layer contains a lower induction coil, which can electromagnetically heat the lower graphite sleeve. The lower flow channel contains an intermediate package and a leak nozzle connected vertically.

[0007] The beneficial effects of the present invention are: the heating tundish device can continuously raise the temperature, and the temperature of the tundish can be raised to ≥1500℃, which solves the problem of large temperature difference between molten steel and tundish and avoids the risk of atomization leakage and blockage. Attached Figure Description

[0008] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0009] Figure 1 This is a front view schematic diagram of the heating intermediate baggage device described in this invention.

[0010] Figure 2 This is a cross-sectional schematic diagram of the heating intermediate baggage device described in this invention.

[0011] Figure 3 yes Figure 2 A schematic diagram of the right side of the middle section.

[0012] Figure 4 This is a diagram of a riser.

[0013] Figure 5 This is a schematic diagram of the lower graphite sleeve.

[0014] The annotations in the attached figures are explained as follows:

[0015] 1. Middle filter; 2. Upper filter; 3. Riser; 4. Upper casing; 5. Upper cover plate; 6. Upper refractory cotton layer; 7. Inner cover plate; 8. Upper induction coil; 9. Upper coil connector; 10. Magnesia sand; 11. Upper shell; 12. Lower refractory cotton layer; 13. Lower induction coil; 14. Support plate; 15. Spray disc; 16. Exhaust nozzle; 17. Intermediate liner; 18. Inner graphite sleeve; 19. Outer graphite sleeve; 20. Lower insulation cotton layer; 21. Lower shell; 22. Lower copper plate; 23. Heat insulation plate; 24. Upper copper plate; 25. Lower cover plate; 26. Intermediate partition plate; 27. Lower filter; 28. Spiral flow channel; 29. ​​Magnesia sand block layer; 30. Upper insulation cotton layer; 31. Upper graphite sleeve; 32. Side filter; 33. Lower casing; 34. Inner blind hole flow channel; 35. Lower coil connector;

[0016] 301. First inner diameter section; 302. Second inner diameter section; 303. Third inner diameter section; 304. Fourth inner diameter section; 305. First annular transition surface; 306. Second annular transition surface; 307. Third annular transition surface; 308. First outer diameter section; 309. Second outer diameter section; 3010. Third outer diameter section;

[0017] 1801. Upper section of graphite inner sleeve; 1802. Lower section of graphite inner sleeve;

[0018] 1901. Upper section of the graphite jacket; 1902. Lower section of the graphite jacket. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] A heatable intermediate package device includes an upper package body 4 and a lower package body 33 arranged vertically. The upper package body 4 includes an upper shell 11, an upper electromagnetic induction layer, an upper graphite sleeve 31, and a riser 3, arranged sequentially from the outside to the inside in a horizontal direction. The upper electromagnetic induction layer contains an upper induction coil 8, which can electromagnetically heat the upper graphite sleeve 31. The lower package body 33 includes a lower shell 21, a lower electromagnetic induction layer, a lower graphite sleeve, and a lower flow channel, arranged sequentially from the outside to the inside in a horizontal direction. The lower electromagnetic induction layer contains a lower induction coil 13, which can electromagnetically heat the lower graphite sleeve. The lower flow channel includes an intermediate package 17 and a leak nozzle 16 connected vertically. Figures 1 to 3 As shown.

[0021] In this embodiment, the riser 3 has an upright cylindrical structure. The riser 3 contains internal channels and sidewalls arranged inside and outside. The inner surface of the riser 3 contains a first inner diameter section 301, a second inner diameter section 302, a third inner diameter section 303 and a fourth inner diameter section 304 arranged sequentially from top to bottom. The first inner diameter section 301, the second inner diameter section 302 and the third inner diameter section 303 are all frustum-shaped structures with the top end facing down and the bottom end facing up.

[0022] The axes of the first inner diameter segment 301, the second inner diameter segment 302, the third inner diameter segment 303, and the fourth inner diameter segment 304 coincide. The lower inner diameter of the first inner diameter segment 301 is larger than the upper inner diameter of the second inner diameter segment 302, the lower inner diameter of the second inner diameter segment 302 is larger than the upper inner diameter of the third inner diameter segment 303, and the lower inner diameter of the third inner diameter segment 303 is larger than the upper inner diameter of the fourth inner diameter segment 304. The cylindrical structure of the fourth inner diameter segment 304 is as follows: Figures 3 to 4 As shown.

[0023] In this embodiment, the taper of the first inner diameter segment 301, the taper of the second inner diameter segment 302, and the taper of the third inner diameter segment 303 are basically the same. A first annular transition surface 305 is formed between the first inner diameter segment 301 and the second inner diameter segment 302, a second annular transition surface 306 is formed between the second inner diameter segment 302 and the third inner diameter segment 303, and a third annular transition surface 307 is formed between the third inner diameter segment 303 and the fourth inner diameter segment 304.

[0024] In this embodiment, the riser 3 has an upper filter 2, a middle filter 1, and a lower filter 27 arranged in its internal channel. The upper filter 2 is stacked and connected to the first annular transition surface 305, and the diameter of the upper filter 2 is equal to the outer diameter of the first annular transition surface 305. The middle filter 1 is stacked and connected to the second annular transition surface 306, and the diameter of the middle filter 1 is equal to the outer diameter of the second annular transition surface 306. The lower filter 27 is stacked and connected to the third annular transition surface 307, and the diameter of the lower filter 27 is equal to the outer diameter of the third annular transition surface 307.

[0025] In this embodiment, a spiral flow channel 28 is provided inside the side wall of the riser 3. The spiral flow channel 28 is sleeved outside the internal channel of the riser 3. The upper end of the spiral flow channel 28 is the inlet end, which is located inside the first annular transition surface 305. The lower end of the spiral flow channel 28 is the outlet end, which is located on the lower surface of the riser 3. The lower end of the spiral flow channel 28 and the lower end of the internal channel of the riser 3 are both corresponding to the upper end of the tundish 17. The liquid discharged from the spiral flow channel 28 and the internal channel of the riser 3 can both enter the tundish 17.

[0026] In this embodiment, the riser 3 is further provided with a plurality of (e.g., four to six) internal blind hole channels 34. These internal blind hole channels 34 are evenly spaced along the circumference of the riser 3 and extend along the diameter of the riser 3. The inlet end of each internal blind hole channel 34 is located in the third inner diameter section 303. A side filter 32 is provided at the inlet end of each internal blind hole channel 34. A spiral channel 28 passes through the internal blind hole channels 34 and is connected to them. Liquid in the internal channels of the riser 3 can pass sequentially through the internal blind hole channels 34 and the spiral channel 28 and then be discharged from the lower end of the spiral channel 28. Figure 3 and Figure 4 As shown.

[0027] In this embodiment, the outer surface of the riser 3 contains a first outer diameter section 308, a second outer diameter section 309, and a third outer diameter section 3010 arranged sequentially from top to bottom. The diameter of the first outer diameter section 308 is smaller than the diameter of the second outer diameter section 309, and the diameter of the second outer diameter section 309 is smaller than the diameter of the third outer diameter section 3010. The upper graphite sleeve 31 is fitted over the first outer diameter section 308 and the second outer diameter section 309. The outer diameter of the upper graphite sleeve 31 is equal to the outer diameter of the third outer diameter section 3010. An upper thermal insulation layer 30 is fitted between the upper electromagnetic induction layer and the upper graphite sleeve 31. The upper end of the upper thermal insulation layer 30 is flush with the upper end of the upper graphite sleeve 31, and the lower end of the upper thermal insulation layer 30 is flush with the lower end of the third outer diameter section 3010. The upper electromagnetic induction layer also contains magnesium sand 10, and the upper induction coil 8 is a double-turn water-cooled coil.

[0028] The upper induction coil 8 is a conventional double-turn water-cooled coil. Cooling water can circulate inside the upper induction coil 8, while the outside of the upper induction coil 8 is energized without interference. The upper induction coil 8 is connected to an upper coil connector 9, which is located outside the upper housing 11. The heating power of the upper induction coil 8 can be 50kW-60kW, for example, 55kW.

[0029] In this embodiment, an annular upper cover plate 5 is provided at the upper end of the upper package 4. Along the diameter direction of the upper cover plate 5, the outer side of the upper cover plate 5 is connected and fixed to the upper end of the upper shell 11, and the inner side of the upper cover plate 5 is connected and fixed to the upper end of the riser 3. An annular inner cover plate 7 is provided between the upper cover plate 5 and the upper graphite sleeve 31. The inner diameter of the inner cover plate 7 is slightly larger than the inner diameter of the upper end of the upper graphite sleeve 31, and the outer diameter of the inner cover plate 7 is larger than the outer diameter of the upper insulation cotton layer 30. An upper refractory cotton layer 6 is provided between the inner cover plate 7 and the upper graphite sleeve 31. An annular intermediate partition 26 is provided between the upper package 4 and the lower package 33. A lower refractory cotton layer 12 is provided between the riser 3 and the intermediate partition 26.

[0030] In this embodiment, the lower graphite sleeve includes an inner graphite sleeve 18 and an outer graphite sleeve 19. The inner surface of the inner graphite sleeve 18 includes an upper graphite sleeve 1801 and a lower graphite sleeve 1802 arranged vertically. The upper graphite sleeve 1801 is matched and connected to the outer surface of the intermediate liner 17, and the lower graphite sleeve 1802 is matched and connected to the outer surface of the middle and upper parts of the nozzle 16. The inner surface of the outer graphite sleeve 19 includes an upper graphite sleeve 1801 and a lower graphite sleeve 19 arranged vertically. Section 1901 and lower section 1902 of graphite jacket, upper section 1901 of graphite jacket is matched and connected to the outer surface of graphite inner sleeve 18, lower section 1902 of graphite jacket is matched and connected to the lower outer surface of nozzle 16, lower end of lower body 33 is provided with support plate 14, nozzle 16 passes through support plate 14, lower end of nozzle 16 is located below support plate 14, lower end of nozzle 16 is covered with spray plate 15, support plate 14 and spray plate 15 are connected vertically, such as Figure 3 and Figure 5 As shown.

[0031] In this embodiment, the lower electromagnetic induction layer and the lower graphite sleeve contain an inner and outer layer of magnesium abrasive block 29 and a lower insulation cotton layer 20. The lower electromagnetic induction layer also contains magnesium abrasive 10. The lower induction coil 13 is a double-turn water-cooled coil. An annular lower cover plate 25 is provided inside the upper end of the lower casing 33. Along the diameter direction of the lower cover plate 25, the inner side of the lower cover plate 25 is connected to the upper end of the intermediate casing 17. Between the lower cover plate 25 and the lower graphite sleeve, there are a lower copper plate 22, a heat insulation plate 23, and an upper copper plate 24 stacked sequentially from bottom to top. The lower copper plate 22, the heat insulation plate 23, and the upper copper plate 24 are all annular. The outer diameters of the lower copper plate 22, the heat insulation plate 23, and the upper copper plate 24 are all larger than the outer diameter of the lower insulation cotton layer 20. The outer diameters of the lower cover plate 25, the lower copper plate 22, the heat insulation plate 23, and the upper copper plate 24 are the same. Figures 1 to 3 As shown.

[0032] The lower induction coil 13 is a conventional double-turn water-cooled coil. Cooling water can circulate inside the lower induction coil 13, while the outside of the lower induction coil 13 is energized without interference. The lower induction coil 13 is connected to a lower coil connector 35, which is located outside the lower housing 21. The heating power of the lower induction coil 13 can be 60kW-70kW, for example, 65kW.

[0033] In this embodiment, the upper ladle body 4 and the lower ladle body 33 are separated by a middle partition 26. The riser 3, the middle partition 26 and the lower cover plate 25 are stacked sequentially from top to bottom. The upper end of the riser 3 is the inlet end of the heatable intermediate ladle device, and the lower end of the leak 16 is the outlet end of the heatable intermediate ladle device. After entering from the upper end of the riser 3, the liquid can pass through the riser 3, the intermediate ladle 17 and the leak 16 and then be discharged from the lower end of the leak 16. The gap between the intermediate ladle 17 and the leak 16 is bonded with refractory mortar material to achieve a tight bond between the intermediate ladle 17 and the leak 16.

[0034] The working process of the heated intermediate package device is described below.

[0035] The upper coil connector 9 and the lower coil connector 35 are connected to high-frequency electricity. The lower induction coil 13 induction heats the graphite inner sleeve 18 and the graphite outer sleeve 19, while the upper induction coil 8 induction heats the upper graphite sleeve 31. The graphite outer sleeve 19 continuously heats the lower part of the nozzle 16, whose lower inner diameter is φ4mm. The graphite inner sleeve 18 continuously heats the tundish 17. After the molten steel in the melting crucible melts, the temperatures of the tundish 17 and the nozzle 16 are measured using an infrared thermometer. The tundish temperature is 1538℃, and the nozzle temperature is 1480℃. Once the molten steel reaches the required temperature, the blower and atomizing gas are turned on for atomization. The molten steel is poured from the upper end of the riser 3 into the heated tundish device, and sprayed out from the lower end of the nozzle 16. This operation is repeated until the molten steel in the crucible is completely atomized. The power is then turned off, and the powder is allowed to cool.

[0036] In this process, after the molten steel enters the heatable tundish device from the upper end of riser 3, it first enters the internal channel of riser 3. The first portion (most of the molten steel) enters from the upper end of the internal channel and exits from the lower end. The second portion enters from the upper end of spiral flow channel 28 and exits from the lower end. The third portion enters from the inlet end of inner blind hole flow channel 34 and exits from the lower end of spiral flow channel 28. All the molten steel discharged from riser 3 enters tundish 17, and all the molten steel in tundish 17 then enters nozzle 16, and finally, all the molten steel is ejected from the lower end of nozzle 16. Figures 1 to 3 As shown.

[0037] The described heated tundish device features an independent structure, simple installation and disassembly, and easy replacement of parts. It is equipped with upper, middle, lower, and side filters. The molten steel flows through these filters into the nozzle, which is replaceable, thus preventing impurities from clogging the nozzle and ensuring stable atomization. Due to the increased temperature of the heated tundish device, the molten steel temperature can be reduced by 50-100°C, mitigating the impact of high temperatures on element loss and improving product quality.

[0038] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical solutions, and embodiments of the present invention can be freely combined and used together.

Claims

1. A heating intermediate batching device, characterized in that, The heatable intermediate package device includes an upper package body (4) and a lower package body (33) arranged vertically. The upper package body (4) contains an upper shell (11), an upper electromagnetic induction layer, an upper graphite sleeve (31), and a riser (3) arranged sequentially from the outside to the inside in the horizontal direction. The upper electromagnetic induction layer contains an upper induction coil (8), which can electromagnetically heat the upper graphite sleeve (31). The lower package body (33) contains a lower shell (21), a lower electromagnetic induction layer, a lower graphite sleeve, and a lower flow channel arranged sequentially from the outside to the inside in the horizontal direction. The lower electromagnetic induction layer contains a lower induction coil (13), which can electromagnetically heat the lower graphite sleeve. The lower flow channel contains an intermediate package (17) and a leak (16) connected vertically. The riser (3) has an upright cylindrical structure. The riser (3) contains internal channels and sidewalls arranged inside and outside. The inner surface of the riser (3) contains a first inner diameter section (301), a second inner diameter section (302), a third inner diameter section (303) and a fourth inner diameter section (304) arranged from top to bottom. The first inner diameter section (301), the second inner diameter section (302) and the third inner diameter section (303) are all frustum-shaped structures with the top end facing down and the bottom end facing up. The lower inner diameter of the third inner diameter section (303) is larger than the upper inner diameter of the fourth inner diameter section (304). A first annular transition surface (305) is formed between the first inner diameter segment (301) and the second inner diameter segment (302), a second annular transition surface (306) is formed between the second inner diameter segment (302) and the third inner diameter segment (303), and a third annular transition surface (307) is formed between the third inner diameter segment (303) and the fourth inner diameter segment (304). The riser (3) has an upper filter (2), a middle filter (1) and a lower filter (27) in its internal channel. The upper filter (2) is stacked and connected to the first annular transition surface (305), the middle filter (1) is stacked and connected to the second annular transition surface (306), and the lower filter (27) is stacked and connected to the third annular transition surface (307). A spiral flow channel (28) is provided inside the side wall of the riser (3). The spiral flow channel (28) is fitted outside the internal channel of the riser (3). The upper end of the spiral flow channel (28) is located on the first annular transition surface (305), and the lower end of the spiral flow channel (28) is located on the lower surface of the riser (3). The lower end of the spiral flow channel (28) and the lower end of the internal channel of the riser (3) are both corresponding to the upper end of the tundish (17). Multiple internal blind hole channels (34) are also provided in the side wall of the riser (3). The internal blind hole channels (34) extend along the diameter direction of the riser (3). The inlet end of the internal blind hole channel (34) is located in the third inner diameter section (303). A side filter (32) is provided at the inlet end of the internal blind hole channel (34). The spiral channel (28) is connected to the internal blind hole channel (34).

2. The heatable intermediate baggage device according to claim 1, characterized in that, The outer surface of the riser (3) contains a first outer diameter section (308), a second outer diameter section (309) and a third outer diameter section (3010) arranged sequentially from top to bottom. The upper graphite sleeve (31) is fitted over the first outer diameter section (308) and the second outer diameter section (309). The outer diameter of the upper graphite sleeve (31) is equal to the outer diameter of the third outer diameter section (3010). An upper thermal insulation layer (30) is fitted between the upper electromagnetic induction layer and the upper graphite sleeve (31). The upper end of the upper thermal insulation layer (30) is flush with the upper end of the upper graphite sleeve (31), and the lower end of the upper thermal insulation layer (30) is flush with the lower end of the third outer diameter section (3010). The upper electromagnetic induction layer also contains magnesium sand (10). The upper induction coil (8) is a double-turn water-cooled coil.

3. The heatable intermediate baggage device according to claim 2, characterized in that, An annular upper cover plate (5) is provided at the upper end of the upper package (4). The outer side of the upper cover plate (5) is connected to the upper end of the upper shell (11). The inner side of the upper cover plate (5) is connected to the upper end of the riser (3). An annular inner cover plate (7) is provided between the upper cover plate (5) and the upper graphite sleeve (31). The inner diameter of the inner cover plate (7) is larger than the inner diameter of the upper end of the upper graphite sleeve (31). The outer diameter of the inner cover plate (7) is larger than the outer diameter of the upper insulation cotton layer (30). An upper refractory cotton layer (6) is provided between the inner cover plate (7) and the upper graphite sleeve (31). An annular middle partition plate (26) is provided between the upper package (4) and the lower package (33). A lower refractory cotton layer (12) is provided between the riser (3) and the middle partition plate (26).

4. The heatable intermediate baggage device according to claim 1, characterized in that, The lower graphite sleeve includes an inner graphite sleeve (18) and an outer graphite sleeve (19). The inner surface of the inner graphite sleeve (18) includes an upper graphite sleeve section (1801) and a lower graphite sleeve section (1802) arranged vertically. The upper graphite sleeve section (1801) is matched and connected to the outer surface of the intermediate package (17), and the lower graphite sleeve section (1802) is matched and connected to the outer surface of the middle and upper parts of the nozzle (16). The inner surface of the outer graphite sleeve (19) It includes an upper section (1901) of graphite jacket and a lower section (1902) of graphite jacket arranged vertically. The upper section (1901) of graphite jacket is matched and connected to the outer surface of the inner graphite jacket (18). The lower section (1902) of graphite jacket is matched and connected to the lower outer surface of the nozzle (16). The lower end of the lower package (33) is provided with a support plate (14). The nozzle (16) passes through the support plate (14). The lower end of the nozzle (16) is covered with a spray plate (15).

5. The heatable intermediate bagging device according to claim 4, characterized in that, Between the lower electromagnetic induction layer and the lower graphite sleeve, there is an inner and outer layer of magnesium sand block (29) and a lower insulation cotton layer (20). The lower electromagnetic induction layer also contains magnesium sand (10). The lower induction coil (13) is a double-turn water-cooled coil. The upper end of the lower package (33) is provided with a lower cover plate (25). The inner side of the lower cover plate (25) is connected to the upper end of the intermediate package (17). Between the lower cover plate (25) and the lower graphite sleeve, there is a lower copper plate (22), a heat insulation plate (23), and an upper copper plate (24) that are stacked sequentially from bottom to top. The lower copper plate (22), the heat insulation plate (23), and the upper copper plate (24) are all annular. The outer diameter of the lower copper plate (22), the outer diameter of the heat insulation plate (23), and the outer diameter of the upper copper plate (24) are all larger than the outer diameter of the lower insulation cotton layer (20).

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