A double-hearth-rod sintering device with a stable temperature field and flow field

Abstract

The present invention discloses a double furnace core rod sintering device with a stable temperature field and flow field, which includes a sintering furnace, a dehydration furnace, an air inlet and waste exhaust treatment device, and a muffle tube arranged inside the sintering furnace and the dehydration furnace. There is a furnace intermediate heat preservation part and a temperature balance area between the sintering furnace and the dehydration furnace. The inside of the muffle tube is provided with a sintering area and a dehydration area. The top of the muffle tube is provided with a muffle tube cover plate. The air inlet and waste exhaust treatment device includes an exhaust hood, an exhaust pipe, and a waste gas treatment device. The exhaust pipe is provided with a fresh air branch with a fresh air valve, a pressure gauge, and a main air valve. A traction device is arranged through the exhaust hood cover plate and the muffle tube cover plate. The lower end of the traction device is installed with a loose body product and inserted into the muffle tube for dehydration sintering. The exhaust hood, the muffle tube, the exhaust pipe, and the waste gas treatment device are connected and communicated. The present invention has the advantages of stable temperature inside the furnace and temperature and pressure inside the muffle tube, reducing the sintering and dehydration operation time and production cost, improving the overall working efficiency, and making the temperature field and flow field relatively stable, etc.

Description

Technical Field

[0002] The present invention relates to the technical field of mandrel sintering devices, in particular to the technical field of a double-furnace mandrel sintering device with a stable temperature field and flow field.

Background Art

[0004] With the development of the optical fiber market, especially in recent years, the prices of raw materials have been rising continuously, while the optical fiber prices have not increased synchronously. For optical fiber preform manufacturers, reducing the manufacturing cost of preforms, reducing raw material consumption and improving production efficiency have become the trend.

[0005] The sintering of the mandrel loose body needs to go through two steps: dehydration and sintering. Both the dehydration and sintering processes need to be carried out at a certain temperature, and chlorine gas, helium gas and oxygen are used for the reaction during the process. Due to the residual water molecules during the deposition of the loose body, the original Si-O-Si chemical bond may intrude hydroxide radicals to form a new chemical bond Si-OH. The chemical bond Si-OH has an absorption effect on light waves with wavelengths of 945nm, 1240nm, and 1383nm. Therefore, chlorine gas is introduced to replace the chemical bond Si-OH with Si-Cl through the reaction, and the generated Si-Cl bond absorbs wavelengths at 25 microns, far from the working band of the optical fiber, that is, the dehydration effect is achieved; helium gas plays a role in ensuring the positive pressure in the furnace during the dehydration process, effectively transferring heat to promote the dehydration reaction, mainly acting as a catalyst; oxygen is used to prevent germanium dioxide in the loose body from being reacted and ensure the refractive index profile. After the loose body is dehydrated, a high-temperature densification process will be carried out to turn the loose body into a glass state.

[0006] At present, most of the mandrel sintering equipment used by domestic preform manufacturers is of a single-furnace structure. Both the dehydration process and the sintering process are completed in the same heating zone. Due to the short dehydration area in single-furnace operation, local dehydration is required, so the dehydration time is long. There is a need for temperature rise waiting between dehydration and sintering, so the operation time is extended. Taking the operation of a 1200mm-long loose body product as an example, the total operation time of a single furnace is about 780 minutes. Taking a 1200mm-long loose body as an example of the dehydration length, the heating section of the normal designed dehydration furnace is 5 zones with a total height of 2000mm (3 zones in the middle are for operation, and the upper and lower two zones are for auxiliary heating). Helium gas needs to be introduced continuously during the sintering and dehydration operation process. The time is long, so the amount of helium gas is large and the cost is high. There are problems such as low operation efficiency, large consumption of helium gas, and unstable temperature, pressure and flow field in the furnace.

Summary of the Invention

[0008] The purpose of the present invention is to solve the problems in the prior art, and propose a double-furnace mandrel sintering device with a stable temperature field and flow field, which can make the temperature in the furnace and the temperature and pressure in the muffle tube stable, reduce the sintering and dehydration operation time and production cost, improve the overall working efficiency and working stability and safety, and make the temperature field and flow field relatively stable.

[0009] To achieve the above object, the present invention provides a double-hearth-rod sintering device with a stable temperature field and flow field, comprising a sintering furnace, a dehydration furnace, an air inlet and waste discharge treatment device, and a muffle tube disposed inside the sintering furnace and the dehydration furnace. A furnace intermediate heat preservation member and a temperature balance zone are provided between the sintering furnace and the dehydration furnace. The inner regions of the muffle tube corresponding to the inside of the sintering furnace and the dehydration furnace are respectively a sintering zone and a dehydration zone. A muffle tube cover plate is provided on the top of the muffle tube. The air inlet and waste discharge treatment device comprises an exhaust hood with an exhaust hood cover plate and an air inlet, an exhaust pipe, and a waste gas treatment device. A fresh air branch with a fresh air valve, a pressure gauge, and a main air valve are provided on the exhaust pipe. A traction device is inserted through the exhaust hood cover plate and the muffle tube cover plate with a clearance fit. A loose body product is installed at the lower end of the traction device and inserted into the muffle tube for dehydration sintering. The exhaust hood, the muffle tube, the exhaust pipe, and the waste gas treatment device are communicated with each other. Both the sintering furnace and the dehydration furnace comprise heat preservation members and heaters.

[0010] Preferably, the sintering furnace comprises a sintering zone heater, a sintering furnace top heat preservation member, a sintering furnace middle heat preservation member, a sintering furnace bottom heat preservation member, and a muffle tube bottom heat preservation member.

[0011] Preferably, the sintering zone heater is inserted through the sintering furnace top heat preservation member, and the lower end of the sintering zone heater is located inside the sintering furnace middle heat preservation member.

[0012] Preferably, the dehydration furnace comprises a dehydration furnace top heat preservation member, a dehydration furnace middle heat preservation member, a dehydration furnace bottom heat preservation member, and a dehydration zone heater. The dehydration zone heater is installed on the inner wall of the dehydration furnace middle heat preservation member.

[0013] Preferably, the number of the dehydration zone heaters is 4, which are respectively a dehydration zone one heater, a dehydration zone two heater, a dehydration zone three heater, and a dehydration zone four heater from top to bottom.

[0014] Preferably, the dehydration zone two heater, the dehydration zone three heater, and the dehydration zone four heater have the same height. The height of the dehydration zone one heater is 50-80% of the height of the dehydration zone two heater, which can reduce the equipment height and the electrical design power while ensuring the temperature stability of the dehydration zone, and reduce the production cost.

[0015] Preferably, the height of the furnace intermediate heat preservation member is 280-600 mm, the height of the dehydration furnace bottom heat preservation member is 80-300 mm, and the height of the dehydration furnace top heat preservation member is 80-450 mm, which can ensure the temperature stability of the four heaters in the dehydration furnace area and the sintering zone temperature stability, and at the same time reduce the heat dissipation and energy loss.

[0016] Preferably, the gap between the muffle tube cover plate and the traction device is 0.5 - 4 mm, which helps to ensure the stable pressure and temperature inside the muffle tube, timely discharge the exhaust gas from the muffle tube, and ensure safety.

[0017] Preferably, the inside of the exhaust pipe is in a negative pressure state and the pressure is maintained at 10 - 60 Pa, and the inside of the muffle tube is in a positive pressure state and the pressure is maintained at 3 - 50 Pa, which facilitates the timely discharge of the exhaust gas discharged from the muffle tube, ensures safety, and at the same time ensures that the process gas inside the muffle tube can fully participate in the reaction, improves the gas utilization rate, and ensures the normal progress of the process.

[0018] Preferably, the height of the temperature balance zone is 10 - 200 mm. The temperature balance zone is between the bottom of the dehydration furnace and the top of the inter-furnace heat preservation part, so that the high temperature in the sintering zone can be dissipated in time, the temperature in the four-zone heater area of the dehydration furnace is kept stable, the height of the equipment can be effectively reduced, which is beneficial to the four-zone heater area of the dehydration furnace to make full use of the temperature in the sintering zone, reduce energy loss, and reduce production costs.

[0019] The beneficial effects of the present invention are as follows: 1. The temperature fluctuations in the sintering furnace and the dehydration furnace are small, making the overall temperature field of the double-furnace core rod sintering device relatively stable, and the sintering effect and dehydration effect of the product are good; 2. The operations of the dehydration furnace and the sintering furnace enable the conversion between dehydration and sintering operations without waiting for heating, effectively reducing the production operation time, effectively improving the production efficiency, reducing the helium consumption and production costs; 3. The pressure fluctuations in the muffle tube are small, facilitating the timely discharge of exhaust gas, ensuring a good and safe operating environment, and enabling the full reaction of industrial gas products; 4. The temperature balance zone is between the inter-furnace heat preservation part and the dehydration furnace, enabling the surface of the muffle tube to be exposed to the air to effectively dissipate the high temperature of sintering, so that the temperature of the four-zone heater of the dehydration furnace is neither affected by the sintering zone nor uses the temperature of the sintering zone to a certain extent for heating, reducing power consumption and production costs; 5. Effectively reducing the height of the dehydration furnace; 6. Through the combined installation design of the main air valve, fresh air valve, the flow field in the exhaust hood, and the gap between the muffle tube cover plate and the traction device, the stability of the pressure, temperature, and gas flow of the overall operation of the device is ensured, and the safe and orderly production is guaranteed.

[0020] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the drawings.

Description of the Drawings

[0022] Figure 1 is the dehydration state schematic diagram of a double-furnace core rod sintering device with a stable temperature field and flow field according to the present invention;

[0023] Figure 2 is the sintering state schematic diagram of a double-furnace core rod sintering device with a stable temperature field and flow field according to the present invention.

[0024] In the figure: 1 - sintering furnace, 2 - dehydration furnace, 3 - muffle tube, 4 - inter - furnace heat - preservation piece, 5 - temperature balance zone, 6 - exhaust hood, 7 - loose - body product, 8 - exhaust pipe, 10 - sintering - zone heater, 11 - top heat - preservation piece of sintering furnace, 12 - middle heat - preservation piece of sintering furnace, 13 - bottom heat - preservation piece of sintering furnace, 14 - bottom heat - preservation piece of muffle tube, 21 - top heat - preservation piece of dehydration furnace, 22 - middle heat - preservation piece of dehydration furnace, 23 - dehydration - zone heater, 24 - bottom heat - preservation piece of dehydration furnace, 31 - sintering zone, 32 - dehydration zone, 33 - muffle - tube cover plate, 61 - exhaust - hood cover plate, 62 - air inlet, 71 - traction device, 81 - pressure gauge, 82 - main air valve, 83 - fresh - air valve, 84 - waste - gas treatment device.

Specific Embodiment

[0026] Refer to Figure 1 、 Figure 2 As shown in

[0027] and

[0028] , a double - furnace - core - rod sintering device with a stable temperature field and flow field according to the present invention includes a sintering furnace 1, a dehydration furnace 2, an air - inlet and waste - gas treatment device, and a muffle tube 3 arranged inside the sintering furnace 1 and the dehydration furnace 2. Process gases such as helium, oxygen, and chlorine enter from the bottom of the muffle tube 3. An inter - furnace heat - preservation piece 4 and a temperature balance zone 5 are arranged between the sintering furnace 1 and the dehydration furnace 2. The internal areas of the muffle tube 3 corresponding to the internal areas of the sintering furnace 1 and the dehydration furnace 2 are a sintering zone 31 and a dehydration zone 32 respectively. A muffle - tube cover plate 33 is arranged on the top of the muffle tube 3. The air - inlet and waste - gas treatment device includes an exhaust hood 6 with an exhaust - hood cover plate 61 and an air inlet 62, an exhaust pipe 8, and a waste - gas treatment device 84. A fresh - air branch with a fresh - air valve 83, a pressure gauge 81, and a main air valve 82 are arranged on the exhaust pipe 8. The exhaust - hood cover plate 61 and the muffle - tube cover plate 33 are provided with a traction device 71 in clearance fit. The lower end of the traction device 71 is installed with a loose - body product 7 and inserted into the muffle tube 3 for dehydration and sintering. The exhaust hood 6, the muffle tube 3, the exhaust pipe 8, and the waste - gas treatment device 84 are connected and communicated. Both the sintering furnace 1 and the dehydration furnace 2 include heat - preservation pieces and heaters;

[0029] The sintering zone heater 10 is inserted through the top heat preservation member 11 of the sintering furnace, and the lower end of the sintering zone heater 10 is located inside the middle heat preservation member 12 of the sintering furnace;

[0030] The dehydration furnace 2 includes a top heat preservation member 21 of the dehydration furnace, a middle heat preservation member 22 of the dehydration furnace, a bottom heat preservation member 24 of the dehydration furnace, and a dehydration zone heater 23. The dehydration zone heater 23 is installed on the inner wall of the middle heat preservation member 22 of the dehydration furnace;

[0031] The number of the dehydration zone heaters 23 is 4, and they are respectively the first dehydration zone heater, the second dehydration zone heater, the third dehydration zone heater, and the fourth dehydration zone heater from top to bottom. The first dehydration zone heater is located on the middle heat preservation member 22 of the dehydration furnace near one end of the top heat preservation member 21 of the dehydration furnace;

[0032] The second dehydration zone heater, the third dehydration zone heater, and the fourth dehydration zone heater have the same height, and the height of the first dehydration zone heater is 70% of the height of the second dehydration zone heater, the third dehydration zone heater, and the fourth dehydration zone heater;

[0033] The height of the inter-furnace heat preservation member 4 is 450 mm, the height of the bottom heat preservation member 24 of the dehydration furnace is 180 mm, the height of the top heat preservation member 21 of the dehydration furnace is 250 mm. The inter-furnace heat preservation member 4 is composed of a top inter-furnace heat preservation member and a bottom inter-furnace heat preservation member. The lower end of the bottom inter-furnace heat preservation member abuts against the top heat preservation member 11 of the sintering furnace;

[0034] The gap between the muffle tube cover plate 33 and the traction device 71 is 2 mm;

[0035] The exhaust pipe 8 is in a negative pressure state and the pressure is maintained at 10 - 60 Pa, and the muffle tube 3 is in a positive pressure state and the pressure is maintained at 3 - 50 Pa;

[0036] The height of the temperature balance zone 5 is 50 mm, and the temperature balance zone 5 is located between the bottom of the dehydration furnace 2 and the top of the inter-furnace heat preservation member 4.

[0037] The working process of the present invention:

[0038] During the working process of a double furnace core rod sintering device with a stable temperature field and flow field according to the present invention, the muffle tube 3 is installed at the center of the dehydration furnace 2 and the sintering furnace 1. The loose body product 7 is installed behind the traction device 71 and then loaded into the muffle tube 3 for dehydration and sintering operations. The loose body product 7 can move up and down with the traction device 71;

[0039] When the device is on standby, the temperature in the dehydration furnace 2 is 1250 °C, and the temperature in the sintering furnace 1 is 1250 °C - 1300 °C. When starting the dehydration operation, the loose body product 7 enters the dehydration area in the corresponding dehydration furnace 2 and can immediately start the dehydration operation. The standby temperature of the sintering furnace 1 at 1250 °C can effectively reduce the power consumption of the equipment by more than 20%, reducing the equipment operation cost. In the later stage of dehydration of the loose body product 7, generally 30 minutes before the dehydration is completed, the sintering furnace 1 starts to heat up. When the temperature rises to the sintering temperature of 1450 °C, the loose body product 7 just completes dehydration. Then, the loose body product 7 is pulled down by the traction device 7 and pulled into the sintering area 31 of the corresponding sintering furnace 1, and then the sintering operation can be carried out until the sintering and dehydration operation is completed;

[0040] During the operation process, process gases such as helium, oxygen, and chlorine enter from the bottom of the muffle tube 3, go upward inside the muffle tube 3 and participate in the reaction with the loose body product 7, and then form waste gas. The waste gas is discharged into the exhaust hood 6 through the gap between the muffle tube cover plate 33 and the traction device 71. Finally, the waste gas follows the air field in the exhaust hood 6 and enters the waste gas treatment device 84 through the exhaust pipe 8 for treatment. It only takes 460 minutes to carry out the sintering and dehydration operation on the 1200 mm long loose body product;

[0041] Since the sintering temperature is higher than the dehydration temperature, the sintering area 31 is located below the dehydration area 32. The high temperature in the sintering area 31 will rise upward, affecting the temperature in the dehydration area 32 and causing the temperature in the dehydration area 32 to be too high to carry out dehydration. Therefore, a temperature balance area 5 is designed between the dehydration furnace 2 and the sintering furnace 1. The temperature balance area 5 is not designed with heat preservation parts, so that the surface of the muffle tube 3 is exposed to the air to dissipate heat from the high temperature of sintering, making the area of the dehydration four-zone heater stable. The height of the temperature balance area 5 is designed to be 10 - 200 mm, so that the temperature of the dehydration four-zone heater is neither affected by the sintering area 31 nor can the temperature of the sintering area 31 be used to a certain extent to increase the temperature, reducing power consumption and production cost. The power of the dehydration four-zone heater is 5% - 50% of the power of the dehydration three-zone heater;

[0042] The bottom of the dehydration furnace 2 is designed with a dehydration furnace bottom heat preservation part 24, with a height generally of 80 - 300 mm, which can effectively increase the heat dissipation distance, make the temperature of the dehydration four-zone heater area stable, and at the same time reduce the heat dissipation of the dehydration four-zone heater and reduce power consumption;

[0043] A furnace intermediate heat preservation part 4 is designed between the temperature balance area 5 and the sintering furnace 1, with a height of 280 - 600 mm, which can effectively maintain the temperature of the sintering area 31, make the temperature of the sintering area 31 stable, and the temperature balance area 5 has less heat dissipation;

[0044] When the loose body product 7 is dehydrated, the traction device 71 will pull it into the dehydration area 32. The effective section (cylindrical part) of the loose body product 7 is placed in the areas corresponding to the dehydration second-zone heater, the dehydration third-zone heater, and the dehydration fourth-zone heater. The top of the dehydration second-zone heater and the bottom of the dehydration third-zone heater are both heaters, and the temperature can be kept stable. The top of the dehydration fourth-zone heater is a heater, and the bottom can be maintained by means of the sintering temperature, so the temperature is also stable. The temperature stability of the 3 heaters can be maintained within ±3°C, meeting the requirements of the dehydration process;

[0045] The dehydration furnace first-zone heater is located at the top of the dehydration furnace and is relatively close to the exhaust hood 6, so a large amount of heat will be dissipated and the temperature fluctuates greatly. Therefore, it is not suitable for dehydration operations. Its main function is to reduce the heat dissipation of the dehydration furnace second-zone heater and keep the temperature stable at the dehydration furnace second-zone heater. The height of the dehydration furnace first-zone heater is designed to be small, generally 50%-80% of the lower dehydration furnace heater, which can effectively reduce the height of the equipment and the equipment investment cost. Since the dehydration furnace 2 adopts four heating sections, its height is 1500 mm;

[0046] The dehydration furnace first-zone heater is designed with a top heat insulation part 21 for the dehydration furnace top, and the height is generally 80-450 mm, which can effectively reduce the heat dissipation of the dehydration furnace first-zone heater and reduce the equipment power;

[0047] An exhaust hood 6 is designed at the top of the muffle tube 3. An air inlet 62 is designed on one side of the exhaust hood 6. An exhaust pipe 8 is provided on the opposite side of the air inlet 62. An exhaust hood cover plate 61 is designed at the top of the exhaust hood 6. The exhaust pipe 8 is connected to the waste gas treatment device 84. The waste gas treatment device 84 sucks air from the exhaust hood 6, so that in the exhaust hood 6, the air enters from the air inlet 62, passes through the exhaust hood, and is discharged from the exhaust pipe 8, and a stable air field is formed in the exhaust hood 6;

[0048] By adjusting the sizes of the main air valve 82 and the fresh air valve 83, the stability of the pressure in the exhaust pipe 8 can be effectively guaranteed. When the pressure of the waste gas treatment device 84 fluctuates, the pressure in the exhaust pipe 8 will maintain a certain value, making the air field in the exhaust hood 6 stable. During equipment debugging, first fully open the fresh air valve 83, and then open the main air valve 82 until the air volume at the end of the exhaust pipe 8 far from the exhaust hood 6 is 300-700 m 3 / h, then adjust the fresh air valve 83 to make the pressure gauge 81 be 10-60 Pa. After that, during operation, the opening degrees of the main air valve 82 and the fresh air valve 83 remain unchanged. At this time, 70% of the air volume at the main air valve 82 will be diverted to the fresh air valve 83. When the pressure of the waste gas treatment device 84 fluctuates, due to the pressure division effect of the pipeline at the fresh air valve 83, the pressure fluctuation of the air field at the distal exhaust hood 6 will be relatively small, achieving the effect of stabilizing the pressure;

[0049] Process gases helium, chlorine and oxygen are introduced into the bottom of the muffle tube 3. Since the gap between the muffle tube cover plate 33 and the traction device 71 is designed within the range of 0.5 to 4 mm, a slightly positive pressure is formed inside the muffle tube 3. The negative pressure in the exhaust pipe 8 generally remains at 10 to 60 Pa, which can ensure the stability of the internal flow field of the exhaust hood 6. At the same time, it can ensure that the internal flow field of the exhaust hood 6 does not affect the pressure inside the muffle tube 3, and can timely discharge the waste gas discharged from the muffle tube 3, ensuring the safe operation of the equipment.

[0050] The above embodiments are illustrative of the present invention and not restrictive thereof. Any solution obtained by simply transforming the present invention falls within the protection scope of the present invention.

Claims

1. A double-hearth rod sintering device with a stable temperature field and flow field, characterized in that: It includes a sintering furnace, a dehydration furnace, an air inlet and waste exhaust treatment device, and a muffle tube passing through the inside of the sintering furnace and the dehydration furnace. There is a furnace intermediate heat preservation part and a temperature balance zone between the sintering furnace and the dehydration furnace. The part of the muffle tube located in the temperature balance zone is exposed to the air for heat dissipation. The temperature balance zone is between the bottom of the dehydration furnace and the top of the furnace intermediate heat preservation part. The inner part of the muffle tube corresponding to the inside areas of the sintering furnace and the dehydration furnace is respectively a sintering zone and a dehydration zone. A muffle tube cover plate is provided on the top of the muffle tube. The air inlet and waste exhaust treatment device includes an exhaust hood with an exhaust hood cover plate and an air inlet, an exhaust pipe, and a waste gas treatment device. The air inlet is flush with the exhaust pipe and is respectively located on both sides of the exhaust hood. A fresh air branch with a fresh air valve, a pressure gauge, and a main air valve are provided on the exhaust pipe. The exhaust hood cover plate and the muffle tube cover plate are provided with a traction device in clearance fit. The lower end of the traction device is installed with a loose body product and inserted into the muffle tube for dehydration and sintering. The exhaust hood, the muffle tube, the exhaust pipe, and the waste gas treatment device are connected and communicated. Both the sintering furnace and the dehydration furnace include a heat preservation part and a heater. The inside of the exhaust pipe is in a negative pressure state and the pressure is maintained at 10 - 60 Pa. The inside of the muffle tube is in a positive pressure state and the pressure is maintained at 3 - 50 Pa.

2. The double-core rod sintering device with a stable temperature field and flow field as described in claim 1, characterized in that: The sintering furnace includes a sintering zone heater, a sintering furnace top heat preservation part, a sintering furnace middle heat preservation part, a sintering furnace bottom heat preservation part, and a muffle tube bottom heat preservation part.

3. The double-hearth rod sintering device with a stable temperature field and flow field as described in claim 2, characterized in that: The sintering zone heater is inserted through the sintering furnace top heat preservation part, and the lower end of the sintering zone heater is located inside the sintering furnace middle heat preservation part.

4. The double-hearth-bar sintering device with a stable temperature field and flow field according to claim 1, characterized in that: The dehydration furnace includes a dehydration furnace top heat preservation part, a dehydration furnace middle heat preservation part, a dehydration furnace bottom heat preservation part, and a dehydration zone heater. The dehydration zone heater is installed on the inner wall of the dehydration furnace middle heat preservation part.

5. The double-hearth rod sintering device with a stable temperature field and flow field according to claim 4, characterized in that: The number of the dehydration zone heaters is 4, and they are respectively a dehydration zone 1 heater, a dehydration zone 2 heater, a dehydration zone 3 heater, and a dehydration zone 4 heater from top to bottom.

6. The double-hearth-rod sintering device with a stable temperature field and flow field according to claim 5, characterized in that: The heights of the dehydration zone 2 heater, the dehydration zone 3 heater, and the dehydration zone 4 heater are the same. The height of the dehydration zone 1 heater is 50 - 80% of the height of the dehydration zone 2 heater.

7. The double-hearth-bar sintering device with a stable temperature field and flow field as described in claim 1, wherein: The height of the furnace intermediate heat preservation part is 280 - 600 mm, the height of the dehydration furnace bottom heat preservation part is 80 - 300 mm, and the height of the dehydration furnace top heat preservation part is 80 - 450 mm.

8. The double-hearth-rod sintering device with a stable temperature field and flow field as described in claim 1, wherein: The gap between the muffle tube cover plate and the traction device is 0.5 - 4 mm.

9. The double-core rod sintering device with a stable temperature field and flow field according to any one of claims 1 to 8, characterized in that: The height of the temperature balance zone is 10 - 200 mm.

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