A microwave-hot air hybrid pre-oxidation furnace and its process using a slotted antenna

Abstract

This invention discloses a microwave and hot air hybrid pre-oxidation furnace and process using slotted antennas. The furnace body has an inner cavity divided into a central wire feeding zone and two side air inlet and outlet zones by two sets of flow equalizers. Several guide rollers are installed in both the air inlet and outlet zones to guide the pre-oxidized filaments in a reciprocating zigzag pattern. The pre-oxidized filaments pass around the guide rollers in the wire feeding zone and then fold back towards the wire feeding zone. The furnace also includes several slotted antennas, one and two. Slotted antenna one is installed on the top or bottom surface of the wire feeding zone. The air inlet and outlet zones have opposite end faces, and slotted antenna two is installed on the end faces. This invention uses hot air and microwaves to heat and pre-oxidize polyacrylonitrile precursor fibers. Using hot air as the base, the polyacrylonitrile precursor fibers can be maintained at a certain heating temperature. Microwaves then assist in the pre-oxidation, improving the pre-oxidation efficiency, shortening the pre-oxidation time and hot air temperature, and significantly enhancing the pre-oxidation efficiency.

Description

Technical Field

[0001] This invention relates to carbon fiber pre-oxidation equipment, and more specifically, to a microwave and hot air hybrid pre-oxidation furnace employing a slotted antenna, and also to a process employing microwave and hot air hybrid heating. Background Technology

[0002] The pre-oxidation furnace is a key piece of equipment in carbon fiber production, and its operational efficiency directly affects product quality and production economics. During the pre-oxidation process, the temperature needs to be controlled within the range of 200-300℃. Hot air is used to treat the PAN precursor fibers, promoting chemical reactions such as cyclization, dehydrogenation, and oxidation, thereby forming a heat-resistant intermediate product with a trapezoidal six-membered ring structure to facilitate subsequent carbonization processes. However, pre-oxidizing carbon fibers solely with hot air results in relatively low heating and oxidation efficiency, which is detrimental to improving the efficiency and energy efficiency of carbon fiber production.

[0003] Therefore, a new solution is needed to address this problem. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a microwave and hot air hybrid pre-oxidation furnace and process using a slot antenna.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A microwave and hot air hybrid pre-oxidation furnace with a slot antenna includes a furnace body. The inner cavity of the furnace body is divided into a middle wire feeding zone and two air inlet and air outlet zones by two sets of flow equalizers. Several guide rollers are installed in the air inlet and air outlet zones to make the pre-oxidized wires feed in a reciprocating folding manner. The pre-oxidized wires pass around the guide rollers from the wire feeding zone and then fold back towards the wire feeding zone.

[0007] It also includes several slot antennas, namely, slot antenna one and slot antenna two. Slot antenna one is installed on the top or bottom surface of the wire feeding area and is used to microwave heat the pre-oxidized wire in the wire feeding area. The air inlet area and air outlet area have opposite end faces. Slot antenna two is installed on the end face and is used to microwave heat the pre-oxidized wire that passes through the guide roller.

[0008] The invention is further configured to include a heater for heating the gas and a fan for conveying the gas, wherein the outlet of the fan is connected to the air inlet area for conveying hot air to the air inlet area, and the air inlet of the fan is connected to the air outlet area for forming a hot air circulation between the furnace body and the heater.

[0009] The present invention is further configured such that each slot antenna is uniformly arranged along the width direction of the wire-walking area and the slot antenna is arranged along the length direction of the wire-walking area; the slot antenna faces the leakage hole of the wire-walking area and the leakage hole is arranged along the length direction of the slot antenna.

[0010] The present invention is further configured such that each slot antenna 2 is evenly arranged along the width direction of the wire feeding area, and the slot antenna 2 is arranged along the vertical direction; the slot antenna 2 opens toward the furnace body through the leakage hole 2, and the leakage hole 2 is arranged along the length direction of the slot antenna 2.

[0011] The present invention is further configured such that each guide roller is arranged in parallel vertically, and each row of slot antennas is laterally opposite to each guide roller.

[0012] The present invention is further configured such that the end face is provided with a plurality of feed ports, and the feed ports correspond one-to-one with the leakage apertures of the second slot antenna; in a single second slot antenna, the height of each leakage aperture is directly opposite to the guide roller.

[0013] The present invention is further configured such that a limiting roller is installed on the lower side of the guide roller near the yarn feeding area, the pre-oxidized yarn wraps around the limiting roller and forms a wrap angle α, and the direction in which the pre-oxidized yarn wraps around the guide roller is opposite to the direction in which it wraps around the limiting roller; the wrap angle α is 20° to 45°.

[0014] The present invention is further configured such that the limiting roller is located on the side of the guide roller facing away from the second slot antenna, the outer diameter of the limiting roller is smaller than that of the guide roller, and the guide roller is able to shield the second slot antenna.

[0015] The present invention is further configured such that the outer diameter of the limiting roller is 1 / 3 to 3 / 4 of the outer diameter of the guide roller, and both the guide roller and the limiting roller are stainless steel rollers;

[0016] The present invention is further configured such that the length of the pre-oxidized fiber passing over the guide roller is L1, the length of the pre-oxidized fiber passing over the limiting roller is L2, and L2 is not less than L1 / 8.

[0017] The present invention also provides a microwave and hot air hybrid heating process, using the pre-oxidation furnace as described in the above embodiments, which can pre-oxidize the pre-oxidized filaments using hot air and microwave.

[0018] In summary, the present invention has the following beneficial effects:

[0019] By using hot air and microwave to pre-oxidize polyacrylonitrile precursor fibers, hot air is used to maintain the fibers at a certain heating temperature, and microwave is used for auxiliary pre-oxidation, which can improve the efficiency of pre-oxidation, shorten the pre-oxidation time and hot air temperature, and significantly improve the pre-oxidation efficiency.

[0020] By installing slotted antennas in the air inlet and outlet zones on both sides of the wire feeding zone, the slotted antennas can microwave heat the end position of the pre-oxidized wire when it turns back, and can also heat the guide roller. This allows the pre-oxidized wire to come into contact with the guide roller at a higher temperature when it passes around the guide roller, thereby improving the pre-oxidation efficiency of the pre-oxidized wire.

[0021] By arranging a limiting roller near the guide roller, the pre-oxidized filament is bent in the opposite direction after passing through the limiting roller, which can quickly apply reverse force to the pre-oxidized filament. This allows the force and shrinkage on the inner and outer sides of the fiber to be compensated in the opposite direction, so as to maintain the cortical state on both sides of the pre-oxidized filament and quickly adjust the state on both sides of the pre-oxidized filament to a nearly uniform state. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a microwave-hot air hybrid pre-oxidation furnace using a slotted antenna, as shown in Example 1.

[0023] Figure 2 This is a schematic diagram of the structure of the guide roller and the limiting roller in Example 1;

[0024] Figure 3 This is a schematic diagram of the structure of slot antenna one in Embodiment 1;

[0025] Figure 4 This is a schematic diagram of the structure of slot antenna 2 in Embodiment 1;

[0026] Figure 5 This is a schematic diagram of the furnace body and hot air passage in Example 1;

[0027] Figure 6 This is a schematic diagram of the furnace body and hot air passage in Example 2;

[0028] Figure 7 This is a schematic diagram of the connecting part of the hot air channel in Example 2;

[0029] Figure 8 This is a schematic diagram of a microwave-hot air hybrid pre-oxidation furnace using a slot antenna, as shown in Example 3.

[0030] Figure 9 This is a schematic diagram of one state of the shielding in Embodiment 3;

[0031] Figure 10 This is a schematic diagram of another state of the shielding in Embodiment 3.

[0032] Reference numerals: Furnace body 1; Air inlet zone 101; Wire feeding zone 102; Air outlet zone 103; Feed port 104; Wave-transparent plate 105; Flow equalizer 2; Slot antenna one 3; Leakage hole one 31; Slot antenna two 4; Leakage hole two 41; Guide roller 5; Limiting roller 6; Microwave source 7; Wave-transparent plate 8; Hot air channel 9; Heater 91; Fan 92; Connecting part 93; Recessed cavity 931; Shielding cover 932; Through hole 933; Roller 934; Mesh sheet 935; Opening 936; Flow equalization mesh plate 201; Flow equalization cavity 202; Wire feeding through hole 203; Wire feeding tube 204; Wire feeding channel 205; Shielding cover 301; Air outlet side 302; First air outlet 303; Second air outlet 304; Shielding baffle 305. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment discloses a microwave-hot air hybrid pre-oxidation furnace employing a slotted antenna, referring to... Figures 1-5 As shown, the furnace body 1 is divided into three chambers by two sets of flow equalizers 2: the middle wire feeding zone 102 and the air inlet zone 101 and air outlet zone 103 on both sides.

[0036] Reference Figure 5 As shown, the pre-oxidizing furnace in this embodiment also includes a heater 91 and a blower 92. The heater heats the gas, and the blower delivers the heated gas to form hot air. The blower's outlet is connected to the inlet zone 101, delivering hot air to the inlet zone 101. The blower's inlet is connected to the outlet zone 103, forming a hot air circulation between the furnace body 1 and the heater. The flow equalizer 2 is a perforated plate, which can evenly distribute the hot air, ensuring that the hot air is evenly distributed and parallel to the wire feeding direction.

[0037] Hot air enters from the inlet zone 101 and is evenly distributed by the flow equalizer 2. This heats the pre-oxidized yarn in the yarn feeding zone 102 before exiting from the outlet zone 103, where it is reheated by the heater, forming a hot air circulation heating process. During the hot air heating process, the temperature in the inlet zone 101 is maintained at 200-260 degrees Celsius. As the hot air flows from the inlet zone 101 to the outlet zone 103, the temperature decreases slightly. The temperature in the inlet zone 101 is higher than that in the outlet zone 103, with a temperature difference of 20-30 degrees Celsius.

[0038] Reference Figure 1 As shown, several guide rollers 5 are installed in both the air inlet zone 101 and the air outlet zone 103, so that the pre-oxidized wires are fed in a reciprocating folding motion, which can extend the length of the pre-oxidized wires in the wire feeding zone 102, so that the pre-oxidized wires have sufficient hot air heating length in the furnace body 1.

[0039] Several slotted antennas 3 are installed within the wire feeding zone 102 of the furnace body 1, and are mounted on the top surface of the wire feeding zone 102. The slotted antennas 3 are arranged in several rows, with each row distributed along the width of the wire feeding zone 102. Each individual slotted antenna 3 is positioned along the length of the wire feeding zone 102, and each slotted antenna 3 has a downward-facing microwave leakage hole 31. Microwaves can be emitted downwards through the leakage hole 31, forming a microwave heating area within the wire feeding zone 102. This allows for mixed heating using hot air and microwaves within the wire feeding zone 102, improving the heating and pre-oxidation effect on the pre-oxidized wire.

[0040] Correspondingly, several feed ports 104 are provided on the top sidewall of the wire feeding zone 102. The positions of the leakage holes 31 correspond one-to-one with the positions of the feed ports 104, and a wave-transparent plate 8 is installed between the leakage holes 31 and the feed ports 104. The wave-transparent plate 8 is made of fused silica, high-purity alumina, hexagonal boron nitride, or silicon nitride. The wave-transparent plate 8 can form a shield at the feed ports 104, which can prevent hot air from leaking outwards, while allowing microwave irradiation to enter the furnace body 1 normally.

[0041] When the pre-oxidized yarn passes through the guide roller 5, it first passes through the through hole on the flow equalizer 2 from the yarn feeding zone 102, then goes around the guide roller 5, then turns back towards the yarn feeding zone 102, passes through the through hole on the flow equalizer 2, and flows back to the yarn feeding zone 102. The pre-oxidized yarn will form a wrap angle at a certain angle on the surface of the guide roller 5.

[0042] The air inlet zone 101 and the air outlet zone 103 have opposing end faces 7, which are the side walls of the front and rear sides of the furnace body 1. A second slotted antenna 4 is installed on the end face 7, allowing microwave heating of the pre-oxidized wire passing through the air inlet zone 101 and the air outlet zone 103. Furthermore, the microwaves emitted by the second slotted antenna 4 can also heat the guide roller 5. The guide roller 5 is made of stainless steel, which has higher microwave absorption efficiency and can reach higher temperatures. When the pre-oxidized wire contacts and wraps around the guide roller 5, it can come into contact with the higher-temperature guide roller 5, thus improving the pre-oxidation efficiency at the wrapping point.

[0043] A limiting roller 6 is installed on the lower side of the guide roller 5 near the yarn feeding area 102, and the limiting roller 6 is set in a one-to-one correspondence with the guide roller 5. The pre-oxidized yarn wraps around the limiting roller 6 and forms a wrap angle α, and the direction in which the pre-oxidized yarn wraps around the guide roller 5 is opposite to the direction in which it wraps around the limiting roller 6.

[0044] When the pre-oxidized fiber passes around the guide roller 5 and the limiting roller 6, it first passes around the guide roller 5 for auxiliary heating. When the pre-oxidized fiber passes around the guide roller 5, the fiber forms a certain angle of bending outside the guide roller 5. Because the fiber is bent, the inner and outer sides of the fiber surface will experience different degrees of stress and contraction. Under heating, the cortex on the surface will undergo different states of pre-oxidation denaturation, which may lead to deviation of internal stress on both sides of the pre-oxidized fiber, affecting the strength performance of the fiber. The pre-oxidized fiber then passes through the limiting roller 6 and bends in the opposite direction, which can quickly apply reverse force to the pre-oxidized fiber, so that the stress and contraction on the inner and outer sides of the fiber can be reversed to compensate for the stress and contraction, so as to maintain the cortex state on both sides of the pre-oxidized fiber and quickly adjust the state on both sides of the pre-oxidized fiber to a near-uniform state.

[0045] As the pre-oxidized fiber passes through each guide roller 5 and limiting roller 6, a certain tension is maintained on the pre-oxidized fiber. This ensures that the pressure between the pre-oxidized fiber and the corresponding roller is maintained as the fiber passes through these rollers, allowing for reverse bending compensation. In this embodiment, the tension of the pre-oxidized fiber is controlled at 6000-7000 cN.

[0046] Reference Figure 4 As shown, several rows of slotted antennas 2 and 4 are arranged along the width of the wire feeding area 102, and each slotted antenna 2 and 4 is oriented vertically. Several leakage holes 2 and 41 are opened on the side of the slotted antenna 2 and 4 facing the furnace body 1, and these leakage holes 2 and 41 are evenly arranged vertically. The structures of slotted antenna 1 and slotted antenna 2 and 4 are roughly the same, both connected to a microwave source 7. The microwave source 7 can emit microwaves towards the corresponding slotted antenna, and the microwaves can be emitted from the corresponding leakage holes. The slotted antennas can emit microwaves towards the pre-oxidized wire and guide roller 5 to perform microwave-assisted pre-oxidation treatment on the pre-oxidized wire, improving the efficiency of the pre-oxidation treatment.

[0047] A feed port 104 is also provided on end face 7. The number and position of the feed ports 104 on end face 7 correspond one-to-one with the number of leakage holes 41. The microwave signal emitted by the slot antenna 4 can be transmitted into the furnace body 1 through the leakage holes 41 and the feed port 104, which can microwave heat the fiber filaments in the air inlet area 101 and the air outlet area 103. Furthermore, a wave-transparent plate 8 is installed between the leakage holes 41 and the feed port 104 of the slot antenna 4. The wave-transparent plate 8 is made of fused silica, high-purity alumina, hexagonal boron nitride, or silicon nitride. The wave-transparent plate 8 can form a shield at the feed port 104, which can prevent hot air from leaking outwards, while allowing microwave irradiation to enter the furnace body 1 normally.

[0048] Furthermore, the leakage aperture 41 of the slot antenna 2 4 is directly opposite the height of the guide roller 5. The guide rollers 5 are arranged vertically in parallel, and each leakage aperture 41 of the slot antenna 2 4 is laterally opposite to each guide roller 5. Each row of slot antennas 2 4 can heat the guide rollers 5, allowing them to maintain a relatively high temperature. The temperature of the guide rollers 5 is 20-30 degrees Celsius higher than the surrounding hot air. The relatively high temperature of the guide rollers 5 improves the heating and pre-oxidation efficiency at the passing point.

[0049] Normally, when the pre-oxidized fiber passes around the guide roller 5, the angle at which it passes outside the guide roller 5 is about 180°. Due to the reverse limiting action of the limiting roller 6, the limiting roller 6 guides the pre-oxidized fiber in the opposite direction and bends the pre-oxidized fiber in the opposite direction. Therefore, the angle at which it passes outside the guide roller 5 will be slightly greater than 180°.

[0050] Reference Figure 2 As shown, the outer diameter of the limiting roller 6 is 1 / 3 to 3 / 4 of the outer diameter of the guide roller 5, and the wrap angle α of the pre-oxidized wire outside the limiting roller 6 is 20° to 45°. Through a reverse bend of 20° to 45°, a certain reverse bend length is achieved. Specifically, the length of the pre-oxidized wire around the guide roller 5 is L1, and the length of the pre-oxidized wire around the limiting roller 6 is L2. L2 is not less than L1 / 8. Maintaining a certain reverse bend appropriately allows the properties of the two sides of the pre-oxidized wire to be more similar, resulting in more uniform strength properties.

[0051] Furthermore, the limiting roller 6 is located on the side of the guide roller 5 facing away from the second slit antenna 4. The outer diameter of the limiting roller 6 is smaller than that of the guide roller 5, thus creating a shield between the second slit antenna 4 and the limiting roller 6. The guide roller 5 can shield the microwave irradiation from the second slit antenna 4 towards the limiting roller 6, preventing direct microwave irradiation and heating of the limiting roller 6. The limiting roller 6 mainly serves to bend the pre-oxidized filament in the opposite direction, preventing excessively high temperatures at the limiting roller 6 from affecting the cortical state of both sides of the pre-oxidized fiber.

[0052] This embodiment also discloses a microwave and hot air hybrid heating process, which uses the pre-oxidation furnace as described in the above embodiment, and can use hot air and microwave to pre-oxidize the pre-oxidized filaments.

[0053] Example 2

[0054] This embodiment discloses a pre-oxidation furnace using a microwave and hot air hybrid heating method, which is based on Embodiment 1 and further refers to... Figure 5 , Figure 6 Please provide a detailed explanation.

[0055] The two ends of the hot air duct 9 are connected to the air inlet zone 101 and the air outlet zone 103, respectively. Since slotted antennas are installed in the air inlet zone 101 and the air outlet zone 103, microwave wave fields exist within their internal spaces. During equipment operation, microwaves in the air inlet zone 101 and the air outlet zone 103 may leak from the connection points with the hot air duct 9. This leakage causes energy loss and, more seriously, damages other electrical components, affecting the overall lifespan of the equipment.

[0056] Reference Figure 5 , Figure 6 As shown, a connecting portion 93 is formed at the end of the hot air passage 9 and in the side wall of the air inlet area 101 and the wire feeding area 102, which can connect the hot air passage 9 to the chamber of the furnace body 1. A recessed cavity 931 is formed on the inner side of the furnace wall at the connecting portion 93, and the recessed cavity 931 has an opening 936 facing the inner cavity of the furnace body 1.

[0057] A shielding cover 932 is installed on the upper side of the opening 936, which covers the opening 936. The shielding cover 932 has several through holes 933. The through holes 933 allow hot air to pass through and isolate microwaves from passing through.

[0058] Furthermore, a roller 934 is rotatably mounted within the recessed cavity 931, and a plurality of perforated sheets 935 are arranged in a row on the outer periphery of the roller 934. The inner cavity of the recessed cavity 931 forms an arc-shaped structure, and the circle of the inner wall of the arc coincides with the rotation center of the roller 934. During the rotation of the perforated sheets 935, a gap is formed between the edge of the perforated sheets 935 and the inner wall of the recessed cavity 931, forming a narrow slit. The perforations on the surface of the perforated sheets 935, and the gap between the perforated sheets 935 and the inner wall of the recessed cavity 931, all prevent microwave leakage.

[0059] Reference Figure 6 As shown, the hot air channel 9 is connected to the lower side of the recessed cavity 931, and the connection port is located at an eccentric position on the roller 934, roughly tangentially. Furthermore, the through-hole 933 on the shielding cover 932 is only opened at certain locations, directly above the connection port of the hot air channel 9. During the flow of hot air through the connecting part 93, the hot air channel 9 can drive the roller 934 and the mesh sheet 935 within the connecting part 93 to rotate. This allows for normal hot air flow while the multiple mesh sheets 935 within the recessed cavity 931 provide shielding, creating a barrier against microwaves and reducing microwave leakage.

[0060] At the connection between the hot air channel 9 and the furnace body 1, a structure with multiple microwave shielding and leakage prevention is formed. This ensures that the hot air can pass through normally while shielding and blocking the microwaves as much as possible, preventing leakage of microwaves from causing loss and avoiding damage to external electrical components.

[0061] Example 3

[0062] This embodiment discloses a pre-oxidation furnace using a microwave and hot air hybrid heating method, which is based on Embodiment 1 and further refers to... Figures 8-10 Please provide a detailed explanation.

[0063] In this embodiment, the flow equalizer 2 includes two layers of flow equalization mesh plates 201, which are arranged in parallel and have mesh openings for the passage of hot air. In each set of flow equalizers 2, a flow equalization cavity 202 is formed between the two layers of flow equalization mesh plates 201, that is, the inner cavity of the furnace body 1 forms five chambers from left to right, namely the air inlet zone 101, the first flow equalization cavity 202, the wire feeding zone 102, the second flow equalization cavity 202, and the air outlet zone 103.

[0064] Two shielding covers 301 are also installed inside the furnace body 1. The shielding covers 301 are located on the lower side of the flow equalizers 2 on both sides. The shielding cover 301 on the left side is located on the lower side of the air inlet zone 101 and the flow equalizer 202, and the shielding cover 301 on the right side is located on the lower side of the air outlet zone 103 and the flow equalizer 202.

[0065] In this embodiment, the air outlet (left end) of the hot air duct 9 is connected to the left-side shield 301, and the air return (right end) of the hot air duct 9 is connected to the right-side shield 301. An air outlet side 302 is formed on the upper side of the shield 301, and a first air outlet 303 and a second air outlet 304 are formed on the upper side of the air outlet side 302. The first air outlet 303 has a plurality of air outlet through holes, and the second air outlet 304 has a plurality of air outlet through holes.

[0066] In this embodiment, both flow equalization mesh plates 201 are metal mesh plates. The flow equalization mesh plates 201 are provided with wire feeding holes 203 for fiber filaments to pass through. In the same flow equalizer 2, the wire feeding holes 203 of the two flow equalization mesh plates 201 are parallel and opposite to each other. A plurality of wire feeding tubes 204 are fixedly connected between the two flow equalization mesh plates 201. The two ends of the wire feeding tubes 204 are respectively fixedly connected to the wire feeding holes 203 of the two flow equalization mesh plates 201, and a wire feeding channel 205 for fiber filaments to pass through is formed in the middle of the wire feeding tubes 204.

[0067] The wire feed tubes 204 are connected to the flow equalization mesh plates 201 at both ends, and both are made of metal. Heat can be conducted relatively efficiently between the wire feed tubes 204 and the flow equalization mesh plates 201, which can maintain the wire feed tubes 204 at a relatively uniform temperature.

[0068] In the left shield 301, the upper side of the first air outlet 303 is connected to the air inlet area 101, and the upper side of the second air outlet 304 is connected to the flow equalization cavity 202. Hot air can be delivered from the first air outlet 303 and the second air outlet 304 to the air inlet area 101 and the flow equalization cavity 202, respectively. The right shield 301 is roughly symmetrical to the left shield 301. In the right shield 301, the upper side of the first air outlet 303 is connected to the air outlet area 103, and the upper side of the second air outlet 304 is connected to the flow equalization cavity 202. Hot air can be delivered from the first air outlet 303 and the second air outlet 304 to the air outlet area 103 and the flow equalization cavity 202, respectively.

[0069] A shielding baffle 305 is also installed inside the shielding cover 301. The shielding baffle 305 can slide in the left and right direction inside the shielding cover 301 and can slide to the lower side of the first air outlet 303 or the second air outlet 304 to shield the air outlet holes of the first air outlet 303 or the second air outlet 304.

[0070] In this embodiment, during the circulation process, the hot air can switch between the first air outlet 303 and the second air outlet 304 by sliding the shielding baffle 305. When the shielding baffle 305 moves to the first air outlet 303, it can block and seal the first air outlet 303. During the flow process, the hot air can enter the left shielding cover 301 from the hot air channel 9, and then flow upward from the second air outlet 304 of the shielding cover 301. The hot air can enter between the flow equalization mesh plates 201 and enter the furnace body 1. It can flow from the left flow equalization cavity 202 to the middle wire feeding area 102, and then to the right flow equalization cavity 202. Finally, it flows out from the second air outlet 304 of the shielding cover 301 below the flow equalization cavity 202, and then enters the hot air channel 9 from the shielding cover 301. A hot air circulation can be formed between the hot air channel 9, the left shielding cover 301, the left flow equalization cavity 202, the wire feeding area 102, the right flow equalization cavity 202, the right shielding cover 301, and the hot air channel 9. During the hot air circulation heating process, the hot air entering the furnace body 1 first enters the flow equalization chamber 202. Since the flow equalization chamber 202 contains a fiber guide tube 204, the fiber filaments can pass through it, creating a separation between the hot air and the limiting wire. This prevents turbulence generated when the hot air first enters from affecting the fiber filaments and avoids uneven heating caused by uneven hot air. During circulation, the hot air avoids turbulent hot air directly blowing on the fiber filaments. Then, the hot air enters the fiber guide zone 102 from the flow equalization chamber 202. In the fiber guide zone 102, the hot air is in a uniform flow state, maintaining uniform heating of the fibers within the zone and preventing excessive turbulence from causing instability in the fiber filaments.

[0071] During the hot air circulation process, the shielding baffle 305 can be slidably adjusted to move to the second air outlet 304, closing the second air outlet 304 and opening the first air outlet 303. During the hot air purging process, the hot air can enter the air inlet area 101 from the first air outlet 303 on the upper side of the shielding cover 301. The hot air first enters the air inlet area 101, which can heat the ambient temperature in the air inlet area 101 to maintain a suitable temperature. Then, the hot air will move towards... The air flows from the right side, passes through the flow equalizer 2, and enters the yarn feeding zone 102, where it continuously and stably heats the fibers. Then, the hot air enters the right-side air outlet zone 103, flows out from the first air outlet 303 of the shield 301 below the air outlet zone 103, enters the shield 301, and then flows back through the hot air channel 9. When the hot air enters the air outlet zone 103, it can also heat the ambient temperature inside the air outlet zone 103 to maintain it at an appropriate heating temperature.

[0072] In addition, during the hot air circulation process, the shielding baffle 305 can be slidably adjusted to be positioned between the first air outlet 303 and the second air outlet 304, keeping both the first and second air outlets partially open and partially blocked. This allows for adjustment of the openness of the first and second air outlets 303 and 304, creating two hot air flow paths and splitting the hot air between them. This maintains the heat supply to the air inlet zone 101 and the air outlet zone 103 while preventing excessive hot air from directly causing instability and disturbance to the fiber filaments in the air inlet zone 101 and the air outlet zone 103. During the hot air circulation process, the shielding baffle 305 can be adjusted and switched to maintain the furnace body 1 within an appropriate overall range.

[0073] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A microwave-hot air hybrid pre-oxidation furnace employing a slotted antenna, characterized in that, The furnace body (1) is divided into a middle wire feeding zone (102) and two sides of air inlet zone (101) and air outlet zone (103) by two sets of flow equalizers (2). Several guide rollers (5) are installed in the air inlet zone (101) and air outlet zone (103) to make the pre-oxidized wire feed in a reciprocating folding manner. The pre-oxidized wire passes around the guide rollers (5) from the wire feeding zone (102) and then folds back towards the wire feeding zone (102). It also includes several slot antennas (3) and slot antennas (4). The slot antennas (3) are installed on the top or bottom surface of the wire feeding area (102) for microwave heating of the pre-oxidized wire in the wire feeding area (102). The air inlet area (101) and the air outlet area (103) have opposite end faces (7). The slot antennas (4) are installed on the end faces (7) for microwave heating of the pre-oxidized wire that passes through the guide roller (5). Each slot antenna (3) is evenly arranged along the width direction of the wire-walking area (102), and the slot antenna (3) is arranged along the length direction of the wire-walking area (102); the slot antenna (3) opens towards the leakage hole (31) of the wire-walking area (102), and the leakage hole (31) is arranged along the length direction of the slot antenna (3). A limiting roller (6) is installed on the lower side of the guide roller (5) near the wire feeding area (102). The pre-oxidized yarn passes around the limiting roller (6) and forms a wrap angle a. The direction in which the pre-oxidized yarn passes around the guide roller (5) is opposite to the direction in which it passes around the limiting roller (6). The wrap angle a is 20°~45°. It also includes a heater for heating the gas and a fan for conveying the gas. The outlet of the fan is connected to the air inlet area (101) for conveying hot air to the air inlet area (101), and the air inlet of the fan is connected to the air outlet area (103) for forming a hot air circulation between the furnace body (1) and the heater.

2. The microwave / hot air hybrid pre-oxidation furnace using a slotted antenna according to claim 1, characterized in that, Each slot antenna (4) is evenly arranged along the width direction of the wire-feeding area (102), and the slot antenna (4) is set along the vertical direction; the slot antenna (4) opens towards the leakage hole (41) of the furnace body (1), and the leakage hole (41) is arranged along the length direction of the slot antenna (4).

3. The microwave / hot air hybrid pre-oxidation furnace employing a slotted antenna according to claim 2, characterized in that, Each guide roller (5) is arranged in parallel vertically, and each row of slot antennas (4) is laterally opposite to each guide roller (5).

4. The microwave / hot air hybrid pre-oxidation furnace employing a slotted antenna according to claim 3, characterized in that, The end face (7) is provided with a plurality of feed ports (104), and the feed ports (104) correspond one-to-one with the leakage holes (41) of the slot antenna (4); in a single slot antenna (4), the height of each leakage hole (41) is directly opposite to the guide roller (5).

5. The microwave / hot air hybrid pre-oxidation furnace employing a slotted antenna according to claim 1, characterized in that, The limiting roller (6) is located on the side of the guide roller (5) facing away from the second slot antenna (4). The outer diameter of the limiting roller (6) is smaller than that of the guide roller (5). The guide roller (5) can shield the second slot antenna (4).

6. The microwave / hot air hybrid pre-oxidation furnace employing a slotted antenna according to claim 5, characterized in that, The outer diameter of the limiting roller (6) is 1 / 3 to 3 / 4 of the outer diameter of the guide roller (5), and both the guide roller (5) and the limiting roller (6) are stainless steel rollers; The length of the pre-oxidized fiber passing over the guide roller (5) is L1, and the length of the pre-oxidized fiber passing over the limiting roller (6) is L2, where L2 is not less than L1 / 8.

7. A process employing a hybrid microwave and hot air heating method, characterized in that, The microwave-hot air hybrid pre-oxidation furnace with a slotted antenna as described in any one of claims 1-6 is used to pre-oxidize the pre-oxidized filaments using hot air and microwave.

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