A sintering furnace suitable for ceramic tube shell

Abstract

A sintering furnace suitable for ceramic tube shells, comprising a furnace body with an insulation layer inside, a furnace door hinged on the front side wall of the furnace body, a furnace chamber formed in the middle of the insulation layer, the furnace door cover arranged at the front side of the furnace chamber, an air inlet for conveying a reducing atmosphere into the furnace chamber arranged on the inner wall of the insulation layer, and a plurality of heating wires fixed on the inner wall of the insulation layer, the air inlet having a plurality of portions, which are respectively distributed in the upper, lower, left, and right sides of the furnace chamber in a clockwise or counterclockwise direction. By arranging a plurality of air inlets for conveying a reducing atmosphere into the furnace chamber on the inner wall of the insulation layer, and the air inlets being distributed in the clockwise or counterclockwise direction on the four sides of the furnace chamber, the reducing atmosphere forms a clockwise or counterclockwise cyclone in the furnace chamber, so that the product in the furnace body is not oxidized, the heating is more uniform, and the product quality is guaranteed.

Description

Technical Field

[0001] The invention relates to a sintering furnace, in particular to a sintering furnace suitable for a ceramic tube shell. Background Art

[0002] Sintering furnace is a kind of furnace that makes the solid particles of ceramic green body bond to each other at high temperature, the grain grows, the voids (pores) and grain boundaries gradually decrease, and through the transfer of substances, the total volume shrinks, the density increases, and finally becomes a dense polycrystalline sintered body with a certain microstructure. During sintering, it is necessary to accurately control the sintering temperature, protective atmosphere, green body conveying method, heating and cooling speed, etc.

[0003] In the prior art, when the sintering furnace is in use, a mixed atmosphere is delivered into the sintering furnace through an air inlet to cause a reduction reaction. However, the mixed atmosphere will accumulate in the furnace, causing uneven distribution of the mixed atmosphere in the furnace, resulting in insufficient reaction and uneven heating, affecting product quality. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a sintering furnace suitable for a ceramic tube shell.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A sintering furnace suitable for ceramic tube shells, comprising a furnace body with an insulation layer inside, a furnace door hinged on the front side wall of the furnace body, a furnace chamber formed in the middle of the insulation layer, the furnace door cover arranged on the front side of the furnace chamber, an air inlet for conveying a mixed atmosphere into the furnace chamber and a plurality of heating wires fixed on the inner wall of the insulation layer are arranged on the inner wall of the insulation layer, and the air inlet has a plurality of air inlets, which are respectively distributed in the upper, lower, left and right sides of the furnace chamber in a clockwise or counterclockwise direction. By arranging a plurality of air inlets for conveying a mixed atmosphere into the furnace chamber on the inner wall of the insulation layer, and the air inlets are distributed in the clockwise or counterclockwise direction on the four sides of the furnace chamber, the mixed atmosphere forms a clockwise or counterclockwise cyclone in the furnace chamber, so that the product in the furnace body is not oxidized, the heating is more uniform, and the product quality is guaranteed.

[0006] Preferably, the mixed atmosphere comprises hydrogen and nitrogen.

[0007] Preferably, the insulation layer comprises a plurality of air-permeable alumina hollow spherical bricks tightly fixedly connected, and the heating wire is a molybdenum wire. The use of air-permeable alumina hollow spherical bricks makes subsequent cooling smooth, and the alumina content of the air-permeable alumina hollow spherical bricks is 99%, and the density is less than 1.4, so that the temperature in the furnace can be quickly heated (cooled), improving work efficiency.

[0008] Preferably, the sintering furnace suitable for ceramic shells also includes a mixed atmosphere delivery system, which includes a high-temperature humidification system and a low-temperature humidification system that can be switched and connected in the pipeline, the temperature in the high-temperature humidification system is 30°C~80°C, and the temperature in the low-temperature humidification system is 15°C~30°C. By using a mixed atmosphere delivery system including a high-temperature humidification system and a low-temperature humidification system, it is possible to switch between high (low) temperature humidification systems, so that the product can be degreased and sintered smoothly, and the workpiece is prevented from being oxidized due to excessive temperature when it is out of the furnace, which affects the product quality.

[0009] Preferably, the mixed atmosphere delivery system includes a nitrogen storage unit, a hydrogen storage unit, and a gas premixing device connected to the nitrogen storage unit and the hydrogen storage unit through pipelines, respectively; the gas premixing device output port is connected to the input port of the high temperature humidification system and the input port of the low temperature humidification system through pipelines, respectively; the gas premixing device is connected to the multiple air inlets of the furnace body through pipelines, and the output port of the high temperature humidification system and the output port of the low temperature humidification system are connected to the multiple air inlets of the furnace body through pipelines. Different purposes can be achieved and different effects can be formed through different lines, not only can the high (low) temperature humidification system be switched, but also dry nitrogen can be directly input before the sintering furnace starts working, and directly enters the furnace after passing through the gas premixing device, thereby exhausting the air and oxygen in the furnace and preventing explosion after hydrogen is input.

[0010] Preferably, the mixed atmosphere delivery system further comprises a hydrogen inlet pipeline connected to the hydrogen storage unit and the gas premixing device, and a nitrogen inlet pipeline connected to the nitrogen storage unit and the gas premixing device.

[0011] Preferably, the gas premixing device comprises a premixing pipeline and two opposing separators arranged in the premixing pipeline, the two separators are arranged at the top and bottom of the premixing pipeline respectively, the two separators are sawtooth-shaped, and the two separators are symmetrically arranged relative to the center line of the premixing pipeline. When the sawtooth-shaped separator is used in the premixing pipeline, the hydrogen and nitrogen inputted will collide with the separator, so that the hydrogen and nitrogen are mixed more fully and evenly.

[0012] Preferably, the top of the insulation layer is arranged as an upwardly arched furnace roof. The upwardly arched furnace roof is provided to strengthen the hardness of the top, and during the combustion process, even if the arched furnace roof is burned with cracks, the furnace roof will not collapse due to the arched design.

[0013] Preferably, the furnace body is provided with an exhaust gas channel for discharging the exhaust gas in the furnace to the outside, and an automatic ignition device is provided at the outlet of the exhaust gas channel. The exhaust gas is some hydrogen that is not fully burned, and the exhaust hydrogen can be fully burned through the automatic ignition device.

[0014] Preferably, there are four air inlets distributed on the four walls of the furnace, close to the corners where the four walls intersect in a clockwise or counterclockwise direction.

[0015] The scope of the present invention is not limited to the technical solutions formed by a specific combination of the above technical features, but also includes other technical solutions formed by any combination of the above technical features or their equivalent features. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in this application.

[0016] Due to the application of the above technical scheme, the present invention has the following advantages compared with the prior art: 1. The present invention provides a plurality of air inlets for conveying a mixed atmosphere into the furnace by arranging on the inner wall of the insulation layer, and the air inlets are distributed on the four sides of the furnace in a clockwise or counterclockwise direction, so that the mixed atmosphere forms a clockwise or counterclockwise cyclone in the furnace, so that the products in the furnace body are not oxidized, and the heating is more uniform, thereby ensuring the product quality; 2. The use of breathable alumina hollow spherical bricks makes the subsequent cooling smooth. The alumina content in the breathable alumina hollow spherical bricks is 99%, and the density is less than 1.4, so that the temperature in the furnace can be quickly heated (cooled), thereby improving the work efficiency; 3. The mixed atmosphere conveying system including a high-temperature humidification system and a low-temperature humidification system is adopted, and the high (low) temperature humidification system can be switched, so that the product can be smoothly degreased and sintered, and prevented from being discharged from the furnace. The workpiece will be oxidized due to excessive temperature, which will affect the product quality; 4. Different purposes can be achieved and different effects can be formed through different lines. Not only can the high (low) temperature humidification system be switched, but also dry nitrogen can be directly input before the sintering furnace starts working. After passing through the gas premixing device, it will directly enter the furnace, thereby exhausting the air and oxygen in the furnace to prevent explosion after hydrogen is input; 5. A serrated separator is used in the premixing pipeline. The hydrogen and nitrogen input will collide with the separator, making the hydrogen and nitrogen mix more fully and evenly; 6. The hardness of the top is strengthened by setting an upward arched furnace roof. During the combustion process, even if the arched furnace roof is burned with cracks, the furnace roof will not collapse due to its arched design; 7. Most of the waste gas is hydrogen that has not been fully burned. The discharged hydrogen can be fully burned through the automatic ignition device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the perspective structure of the furnace body from the front;

[0018] Figure 2 It is a schematic diagram of the perspective structure of the furnace body from the side;

[0019] Figure 3 Schematic diagram of the premixing pipeline structure;

[0020] Figure 4 It is a schematic diagram of the pipeline of the present invention;

[0021] Wherein: 1. furnace body; 11. insulation layer; 12. furnace chamber; 13. heating wire; 14. air inlet; 15. arched furnace top; 2. furnace door; 3. mixed atmosphere delivery system; 31. high temperature humidification system; 32. low temperature humidification system; 33. gas premixing device; 331. premixing pipeline; 332. separator; 34. hydrogen inlet pipeline; 35. nitrogen inlet pipeline.

[0022] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] refer to Figure 1 and Figure 2 The sintering furnace suitable for ceramic tube shells in this embodiment mainly includes a furnace door 2 hinged on the front side wall of the furnace body 1.

[0024] The furnace body 1 has an insulating layer 11 inside, which is composed of a plurality of breathable hollow alumina spherical bricks. In this embodiment, the alumina content in the breathable hollow alumina spherical bricks is 99%, and the density is less than 1.4, and can even reach 1.0. Such an insulating layer can quickly heat up (cool down) the temperature in the furnace and improve work efficiency. The top of the insulating layer 11 is set as an upwardly arched furnace roof 15, which strengthens the hardness of the top. During the combustion process, even if the arched furnace roof is burned with cracks, the furnace roof will not collapse due to its arched design.

[0025] A furnace chamber 12 is formed in the middle of the insulation layer 11, and the furnace door 2 is covered on the front side of the furnace chamber 12. An air inlet for conveying a mixed atmosphere into the furnace chamber 12 and a plurality of heating wires 13 fixed on the inner wall of the insulation layer 11 are provided on the inner wall of the insulation layer 11. In this embodiment, the heating wires 13 are molybdenum wires, and the mixed atmosphere includes about 15% hydrogen (used as a reducing atmosphere) and about 85% nitrogen.

[0026] like Figure 1 As shown, there are four air inlets 14, which are distributed in the upper, lower, left and right sides of the furnace 12 in a clockwise or counterclockwise direction, so that the mixed atmosphere forms a clockwise or counterclockwise cyclone in the furnace to prevent the product in the furnace from being oxidized, heat it more evenly, and ensure product quality.

[0027] The sintering furnace for ceramic shells in this embodiment also includes a mixed atmosphere delivery system 3, referring to Figure 4 .

[0028] The mixed atmosphere delivery system 3 includes a nitrogen storage unit (not shown), a hydrogen storage unit (not shown), a gas premixing device 33, a high temperature humidification system 31, a low temperature humidification system 32 and pipelines connecting the above.

[0029] Depend on Figure 4 It can be known that the hydrogen storage unit is connected to an input port of the air inlet end of the gas premixing device 33 through the hydrogen air inlet pipeline 34, and the nitrogen storage unit is connected to another input port of the air inlet end of the gas premixing device 33 through the nitrogen air inlet pipeline 35. The air outlet end of the gas premixing device 33 is divided into three channels: the first channel is a channel in which the gas premixing device 33 is directly connected to the air inlet 14 of the furnace body 1; the second channel is a channel in which the gas premixing device 33 is connected to the high-temperature humidification system 31 and then connected to the air inlet 14 of the furnace body 1; the third channel is a channel in which the gas premixing device 33 is connected to the low-temperature humidification system 32 and then connected to the air inlet 14 of the furnace body 1.

[0030] The high temperature humidification system 31 is provided with a device capable of stabilizing the temperature in the moisture chamber at 30°C to 80°C, and the low temperature humidification system 32 is provided with a device capable of stabilizing the temperature in the moisture chamber at 15°C to 30°C.

[0031] The first channel is used before firing. There is a certain amount of air and oxygen in the furnace, and the oxygen content is relatively high. When the oxygen content reaches 4%, there is a risk of explosion when hydrogen is introduced. Therefore, before firing, a nitrogen storage unit is required to transport dry nitrogen to the nitrogen inlet pipeline 35. The dry nitrogen is directly input into the furnace after passing through the gas premixing device 33, and a large amount of oxygen in the furnace is discharged, so that the oxygen content is less than 2% to prevent explosion.

[0032] In the second channel, both the nitrogen storage unit and the hydrogen storage unit are opened to transport gas to the gas premixing device 33 and mix to form a mixed gas. The mixed gas passes through the high-temperature humidification system 31 and brings a large amount of water vapor into the furnace. At the same time, the product in this embodiment is a metal-ceramic mixed product. There is some oxygen in the furnace, which causes partial oxidation of the metal, so that it can be better sintered with the ceramic. The hydrogen in the transported mixed atmosphere (including hydrogen and nitrogen) undergoes a reduction reaction, so that the ceramic and metal are more firmly combined, and the oxygen can be completely reduced to generate water. At this time, the product in the furnace is in the degreasing stage, the organic matter in the product is discharged and a small amount of sintering occurs, and the water vapor is discharged to the outside.

[0033] The third channel is for the product to be sintered after degreasing. At this time, the organic matter needs to be discharged from the furnace. At this time, the low-temperature humidification system 32 is switched to the furnace. Hydrogen and nitrogen enter the furnace after passing through the low-temperature humidification system 32, so that the organic matter is dissolved into water vapor, and the water vapor takes the organic matter out, completing the removal of organic impurities and preventing the workpiece from being oxidized due to excessive temperature when it is out of the furnace.

[0034] refer to Figure 3The gas premixing device 33 includes a premixing pipeline 331 and two opposing separators 332 arranged in the premixing pipeline 331. The two separators 332 are respectively arranged at the top and bottom of the premixing pipeline 331. The two separators 332 are serrated. The two separators 332 are symmetrically arranged relative to the center line of the premixing pipeline 331. The serrated separators are used in the premixing pipeline. The hydrogen and nitrogen input will collide with the separators, so that the hydrogen and nitrogen are mixed more fully and evenly. In the mixed gas, hydrogen accounts for about 15% and nitrogen accounts for about 85%.

[0035] The furnace body 1 is provided with an exhaust gas channel for discharging the exhaust gas in the furnace 12 to the outside, and an automatic ignition device is provided at the outlet of the exhaust gas channel. The exhaust gas is mostly hydrogen that has not been fully burned. The automatic ignition device can make the discharged hydrogen fully burn.

[0036] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A sintering furnace suitable for ceramic tube shells, comprising a furnace body (1) having an insulation layer (11) therein, a furnace door (2) hinged on the front side wall of the furnace body (1), a furnace chamber (12) formed in the middle of the insulation layer (11), the furnace door (2) covering the front side of the furnace chamber (12), an air inlet for conveying a mixed atmosphere into the furnace chamber (12) and a plurality of heating wires (13) fixed on the inner wall of the insulation layer (11), characterized in that: The air inlets (14) are provided in plurality and are respectively distributed in the upper, lower, left, and right sides of the furnace (12) in a clockwise or counterclockwise direction. The sintering furnace suitable for ceramic tube shells also includes a mixed atmosphere delivery system (3). The mixed atmosphere delivery system (3) includes a switchable high-temperature humidification system (31) and a low-temperature humidification system (32) connected in a pipeline. The temperature in the high-temperature humidification system (31) is 30°C to 80°C, and the temperature in the low-temperature humidification system (32) is 15°C to 30°C. The mixed atmosphere delivery system (3) includes a nitrogen storage unit, a hydrogen storage unit, and a gas premixing device (33) connected to the nitrogen storage unit and the hydrogen storage unit through pipelines. The output port of the gas premixing device (33) is respectively connected to the input port of the high-temperature humidification system (31) and the input port of the low-temperature humidification system (32) through pipelines. The gas premixing device (33) is connected to the plurality of air inlets (14) of the furnace body (1) through pipelines. The output port of the high-temperature humidification system (31) and the output port of the low-temperature humidification system (32) are connected to the plurality of air inlets (14) of the furnace body (1) through pipelines, and the gas premixing device (33) comprises a premixing pipeline (331), and two opposing partitions (332) arranged in the premixing pipeline (331), wherein the two partitions (332) are respectively arranged at the top and bottom of the premixing pipeline (331), and the two partitions (332) are sawtooth. The two partitions (332) are symmetrically arranged relative to the center line of the premixing pipeline (331); the top of the insulation layer (11) is arranged as an upwardly arched furnace top (15); the furnace body (1) is provided with an exhaust gas channel for discharging exhaust gas in the furnace (12) to the outside; an automatic ignition device is arranged at the outlet of the exhaust gas channel; and there are four air inlets (14), which are distributed on the surrounding walls of the furnace (12) and close to the corners where the surrounding walls intersect along the clockwise direction or the counterclockwise direction.

2. The sintering furnace suitable for ceramic tube shell according to claim 1, characterized in that: The mixed atmosphere includes hydrogen and nitrogen.

3. The sintering furnace suitable for ceramic tube shell according to claim 1, characterized in that: The thermal insulation layer (11) comprises a plurality of air-permeable hollow alumina spherical bricks that are tightly and fixedly connected, and the heating wire (13) is a molybdenum wire.

4. The sintering furnace suitable for ceramic tube shell according to claim 1, characterized in that: The mixed atmosphere delivery system (3) further comprises a hydrogen inlet pipeline (34) connected to the hydrogen storage unit and the gas premixing device (33), and a nitrogen inlet pipeline (35) connected to the nitrogen storage unit and the gas premixing device (33).

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