Repeatable carbonization and cleaning integrated novel carbonization furnace

Abstract

The invention relates to the field of carbon fiber carbonization, and discloses a repeatable carbonization and cleaning integrated novel carbonization furnace which comprises a shell, a volute-shaped guide device, a quartz tube, a silicon molybdenum rod, a wire releasing / collecting device, an air exhaust pipeline, an air exhauster and a power supply. The shell is a cylindrical hard cavity, one end of the shell is loaded with a volute-shaped guide device, and a hole is formed in the upper end of the shell to reserve a position for an air exhaust pipeline so that the air exhaust pipeline can be connected with an air exhauster. The volute-shaped guide device rotates inwards from the edge of the shell to be connected with the quartz tube, and a protruding ventilation opening is formed in the edge of the volute-shaped guide device. The tube diameter of the quartz tube is gradually reduced in a smooth curve from the joint, and then the quartz tube extends to the other end of the quartz tube in parallel with the minimum tube diameter. The silicon-molybdenum rod is distributed in a cavity between the shell and the quartz tube, is connected with the shell, is U-shaped, and can be bent in a multi-fold manner to increase the length so as to provide heat for preheating of protective gas and carbonization of fiber tows. The wire releasing / collecting device is a roller rotating collector, and the rotating speed and direction of a roller are controlled through independent motors on the two sides.

Description

[0001] The invention relates to a novel carbonization furnace capable of repeated carbonization and cleaning, and belongs to the field of carbon fiber carbonization. Background Art

[0002] Carbonization is one of the necessary processes for preparing polyacrylonitrile-based carbon fibers. The pre-oxidized fiber bundles need to be carbonized at high and low temperatures in a carbonization furnace. Because carbon fiber has a wide range of applications and a large demand, it is not only used in cutting-edge fields such as aerospace and JS, but also in heating wire components, fishing rods and other daily life fields. The spun bundles are usually long, and the carbonization furnace is also designed to fit this feature. The size is relatively large, which greatly reduces its convenience during use. In addition, during the carbonization process, the fiber bundles will inevitably generate some waste and exhaust gas (mostly non-carbon compounds) due to the high temperature. If there is no guiding or collecting device, the waste will accumulate on the inner wall of the furnace chamber for a long time and continue to thicken, affecting the carbonization of the fiber bundles and shortening the use time of the equipment; the exhaust gas will mix with the protective gas introduced, and it may not be possible to ensure an oxygen-free or oxygen-poor environment inside the furnace body. When the temperature drops, it will condense to form corrosive tar, which adheres to the outer surface of the fiber bundle or the inner wall of the furnace chamber, affecting the quality of the carbon fiber and shortening the use time of the equipment. Based on this, the present invention proposes a new type of carbonization furnace that can be repeatedly carbonized and cleaned in one body based on a tubular furnace. By changing the rotation direction of the wire-releasing / wire-collecting rollers at both ends, the fiber bundles are reversed in direction to repeatedly undergo high and low temperature carbonization, thereby greatly shortening the horizontal length of the equipment. The narrow tube effect and the vacuum fan are used to guide the waste and exhaust gas generated by carbonization until they are discharged from the furnace body.

[0003] Patent CN202321048839.3 discloses the structure of a double-tube vertical furnace body heating system, which heats the tube body by arranging horizontally plugged silicon-molybdenum rods at the four corners of the tube body. However, considering that the flue gas generated by the fiber bundle expands due to heat during the carbonization process and has a tendency to move upward, the present invention provides two silicon-molybdenum rods under the tube body and three silicon-molybdenum rods above the tube body, which generate a temperature difference in the vertical direction to form a slight convection, which helps the upper flue gas to be discharged out of the furnace and prevents the accumulation of waste gas.

[0004] Patent CN201120224065.6 discloses a tubular furnace gas preheater, including a steam pipe, and a guide device is provided at the inlet of the steam pipe. The guide device is perpendicular to the inlet of the steam pipe and parallel to the steam pipe in length, so as to control the direction of the steam entering the preheater and make the steam evenly dispersed. However, the guide device of this technology is perpendicular to the inlet of the steam pipe, so that the steam accumulates in the guide device first and then diffuses into the pipe, while the volute-shaped guide device designed in the present invention allows the protective gas introduced to rotate into the tubular furnace and realize long-range preheating of the gas during the rotation process.

[0005] In summary, there is still a lack of carbonization furnace technology that allows the gas to rotate into the tubular furnace and complete preheating during the introduction of protective gas, and uses silicon-molybdenum rods to arrange the exhaust gas and smoke to be smoothly discharged from the furnace body during the carbonization process. Summary of the invention

[0006] In view of the deficiencies of the prior art in the above-mentioned background technology, the present invention provides a new type of carbonization furnace which can repeatedly carbonize and clean in one, which can realize long-range preheating of the protective gas and repeatedly carbonize the carbon fiber precursor. The temperature difference and the narrow tube effect are used to strengthen the airflow to guide the waste and exhaust gas generated in the carbonization process to the location of the exhaust fan through the narrow channel. Combined with a low-power exhaust fan, the waste and exhaust gas can be discharged from the furnace body.

[0007] To achieve the above-mentioned purpose, the technical solution of the present invention is as follows: a new type of carbonization furnace capable of repeated carbonization and cleaning is composed of an outer shell, a volute-shaped guide device, a quartz tube, a silicon-molybdenum rod, a wire unwinding / collecting device, an exhaust pipe, an exhaust fan and a power supply.

[0008] The outer shell is a cylindrical hard chamber, with a volute-shaped guide device at one end and a hole at the upper end to reserve a position for the exhaust pipe to connect to the exhaust fan. It is used to accommodate and protect internal components such as the quartz tube.

[0009] The volute-shaped guide device rotates from the edge of the outer shell to gradually shrink inwardly until it is connected to the quartz tube. A raised vent is provided at the edge. The protective gas is blown into the chamber from the vent, rotates around the volute-shaped pipe into the chamber, and in the process, the heat radiated by the silicon-molybdenum rod is used for long-range preheating, thereby reducing the temperature difference between the protective gas and the quartz tube and preventing heat loss. The volute-shaped guide device is connected to the quartz tube and is provided with a plurality of fine air holes with a diameter of 2-3mm around the pipe, so that the preheated protective gas is sprayed into the quartz tube at 360°. The small aperture limits the air flow rate, so that the air flow output is less than the air flow input. The gas is continuously accumulated in the chamber to form a high-pressure environment in the quartz tube. Under the action of pressure, the flow rate of the gas ejected from each air hole is slightly different, so that the protective gas is evenly filled in the quartz tube.

[0010] The diameter of the quartz tube gradually decreases to 5-10mm in a smooth curve from the connection with the volute-shaped guide device, and then extends in parallel to the other end of the quartz tube with the minimum diameter. The minimum diameter shall not be less than the diameter of the fiber bundle. The structure of the gradually decreasing pipeline is constructed to increase the gas flow rate by utilizing the narrow tube effect to transport the waste and exhaust gas generated by carbonization to the other end of the pipeline along the gas flow direction and extract them through the exhaust pipeline. In order to make the smoke and exhaust gas generated by carbonization more smoothly discharged, a hole is opened around the pipeline near one end of the exhaust pipeline, and the hole diameter is 1-5mm.

[0011] The silicon-molybdenum rods are distributed in the chamber between the shell and the quartz tube and connected to the shell. The silicon-molybdenum rods are U-shaped and can be bent multiple times to increase the length to provide heat for preheating the protective gas and carbonizing the fiber bundles. The flue gas generated by carbonization moves upward due to heat. In order to prevent the flue gas from accumulating above the shell chamber, several silicon-molybdenum rods are arranged on and below the quartz tube. On the premise that the heat released by all the quartz tubes in the furnace reaches the temperature required for this carbonization, the total heat generated by the silicon-molybdenum rods above is guaranteed to be 110% of the total heat generated by the silicon-molybdenum rods below, so as to strengthen the heating of the gas above the chamber and form a slight convection in the vertical direction, which helps the flue gas above to be discharged smoothly out of the furnace. The silicon-molybdenum rod electric heating elements can be used alone. Before the fiber bundle enters the carbonization furnace for the first time, the heating temperature of the silicon-molybdenum rod is controlled to be 1300°C; after the first carbonization, the fiber bundle turns around and enters the carbonization furnace for the second time, and the heating temperature of the silicon-molybdenum rod is adjusted to 1350°C; after the second carbonization, the fiber bundle turns around and enters the carbonization furnace for the third time, and the heating temperature of the silicon-molybdenum rod is adjusted to 1400°C; after the third carbonization, the fiber bundle turns around and enters the carbonization furnace for the fourth time, and the heating temperature of the silicon-molybdenum rod is adjusted to 1450°C; after the fourth carbonization, the fiber bundle turns around and enters the carbonization furnace for the fifth time, and the heating temperature of the silicon-molybdenum rod is adjusted to 1500°C, so that the carbonization temperature in the furnace rises in a step-by-step manner, and high and low temperature carbonization is repeated.

[0012] The wire laying / collecting device is a roller rotating collector, which is located on both sides outside the carbonization furnace and keeps aligned in the horizontal direction. The rotation speed of the roller is controlled by independent motors on both sides. The rotation speed of the front roller in the wire feeding direction needs to be slightly greater than that of the rear roller to increase the tension on the fiber bundle to prevent the fiber bundle from slipping or being rolled away by the rear roller. After the same device completes the wire laying or collecting work, it can take on another work by changing the rotation direction of the motor. When the fiber bundle with a length of 2-3 times the length of the carbonization furnace is wound on the collection shaft, the rotation direction of the roller is changed to prevent the fiber bundle on the collection shaft from being too short to undergo repeated carbonization and the fiber bundle from being too long to undergo repeated carbonization unevenly.

[0013] The beneficial effects of the present invention are that the same device can be used to preheat gas and carbonize fiber precursors, thus saving heat sources; the temperature difference and narrow tube effect are used to enhance the exhaust of smoke and exhaust gas through structural design, so that sewage can be discharged in time, the environment in the carbonization furnace can be improved, and the quality of carbon fiber can be improved; by changing the rotation direction of the roller, the fiber bundle can be reciprocated into the carbonization furnace to achieve the purpose of repeated carbonization and shorten the horizontal length of the existing carbonization furnace; by adjusting the heating power of the silicon-molybdenum rod, the temperature of the fiber bundle entering the carbonization furnace for the nth time can be changed to achieve temperature-step carbonization. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a cross-sectional view of a novel carbonization furnace capable of repeated carbonization and cleaning in one body according to the present invention.

[0015] Figure 2 It is a simplified left view of the present invention.

[0016] Figure 1 Middle: 1. Shell, 2. Silicon molybdenum rod, 3. Quartz tube, 4. Wire release / wire collection device, 5. Volute-shaped guide device, 6. Vent, 7. Exhaust pipe, 8. Air hole, 9. Drain hole.

[0017] Figure 2 Middle: 1. Shell, 2. Silicon molybdenum rod, 3. Quartz tube, 7. Exhaust pipe. DETAILED DESCRIPTION

[0018] The specific implementation method of the present invention is further described below in conjunction with the accompanying drawings:

[0019] To achieve the above-mentioned purpose, the technical solution of the present invention is as follows: a new type of carbonization furnace capable of repeated carbonization and cleaning is composed of a shell (1), a volute-shaped guide device (5), a quartz tube (3), a silicon-molybdenum rod (2), a wire unwinding / collecting device (4), an exhaust pipe (7), an exhaust fan and a power supply.

[0020] The outer shell (1) is a cylindrical hard chamber, one end of which is loaded with a volute-shaped guide device (5), and the upper end is opened to reserve a position for an exhaust pipe (7) to be connected to an exhaust machine.

[0021] The volute-shaped guide device (5) rotates from the edge of the outer shell to gradually shrink inwardly until it is connected to the quartz tube (3). A raised vent (6) is provided at the edge. The protective gas is blown into the chamber from the vent, rotates around the volute-shaped pipe into the chamber, and in the process, the heat radiated by the silicon-molybdenum rod (2) is used for long-range preheating, thereby reducing the temperature difference between the protective gas and the quartz tube (3) and preventing heat loss. A plurality of fine air holes (8) with a diameter of 2-3 mm are provided around the pipe at the connection between the volute-shaped guide device (5) and the quartz tube (3), so that the preheated protective gas is sprayed into the quartz tube (3) at 360 degrees. The small aperture limits the air flow rate, so that the air flow output is less than the air flow input. The gas is continuously accumulated in the chamber to form a high-pressure environment in the quartz tube (3). Under the action of pressure, the flow rate of the gas sprayed from each air hole (8) is relatively small, so that the protective gas is evenly filled in the quartz tube (3).

[0022] The diameter of the quartz tube (3) gradually decreases to 5-10 mm in a smooth curve from the connection point with the volute-shaped guide device (5), and then extends in parallel to the other end of the quartz tube (3) with the minimum diameter. The minimum diameter is not less than the diameter of the fiber bundle. The structure of the gradually decreasing pipeline is constructed to increase the gas flow rate by using the narrow tube effect, so that the waste and exhaust gas generated by carbonization are transported to the other end of the pipeline along the gas flow direction and extracted through the exhaust pipeline (7). In order to make the smoke and exhaust gas generated by carbonization more smoothly discharged, a hole (9) is opened around the pipeline at one end of the quartz tube (3) close to the exhaust pipeline (7), and the hole diameter is 1-5 mm.

[0023] The silicon-molybdenum rods (2) are distributed in the chamber between the shell (1) and the quartz tube (3) and connected to the shell. The silicon-molybdenum rods (2) are U-shaped and can be bent multiple times to increase the length to provide heat for preheating the protective gas and carbonizing the fiber bundles. The smoke generated by carbonization moves upward due to heat. In order to prevent the smoke from accumulating above the chamber of the shell (1), a number of silicon-molybdenum rods (2) are respectively arranged above and below the quartz tube (3). Under the premise that the heat released by all the quartz tubes (3) in the furnace reaches the temperature required for this carbonization, the total heat generated by the silicon-molybdenum rods (2) above is guaranteed to be 110% of the total heat generated by the silicon-molybdenum rods (2) below, so as to strengthen the heating of the gas above the chamber and form a slight convection in the vertical direction, which helps the smoke above to be discharged smoothly out of the furnace. The silicon-molybdenum rod (2) electric heating element can be used alone. Before the fiber bundle enters the carbonization furnace for the first time, the heating temperature of the silicon-molybdenum rod (2) is controlled to be 1300°C. After the first carbonization is completed, the fiber bundle turns around and enters the carbonization furnace for the second time, and the heating temperature of the silicon-molybdenum rod (2) is adjusted to 1350°C. After the second carbonization is completed, the fiber bundle turns around and enters the carbonization furnace for the third time, and the heating temperature of the silicon-molybdenum rod (2) is adjusted to 1400°C. After the third carbonization is completed, the fiber bundle turns around and enters the carbonization furnace for the fourth time, and the heating temperature of the silicon-molybdenum rod (2) is adjusted to 1450°C. After the fourth carbonization is completed, the fiber bundle turns around and enters the carbonization furnace for the fifth time, and the heating temperature of the silicon-molybdenum rod (2) is adjusted to 1500°C, so that the carbonization temperature in the furnace rises in a step-by-step manner, and high and low temperature carbonization is repeated.

[0024] The wire laying / collecting device (4) is a roller rotating collector, which is located on both sides outside the carbonization furnace and keeps aligned in the horizontal direction. The rotation speed of the roller is controlled by independent motors on both sides. In the wire feeding direction, the rotation speed of the front roller needs to be slightly greater than that of the rear roller to increase the tension on the fiber bundle to prevent the fiber bundle from slipping or being rolled away by the rear roller. After the same device completes the wire laying or collecting work, it can take on another work by changing the rotation direction of the motor. Changing the rotation direction of the motor depends on the motor model and there are many ways. Now only one reference scheme is provided, which is to use a bipolar excitation power supply to change the direction of the excitation current to change the rotation direction of the DC motor with an excitation winding. When a fiber bundle with a length of 2-3 times the length of the carbonization furnace is wound on the collection shaft, the rotation direction of the roller can be changed to prevent the fiber bundle on the collection shaft from being too short to undergo repeated carbonization and the fiber bundle from being too long to undergo repeated carbonization unevenly.

[0025] When the device is working, the silicon-molybdenum rod electric heating element is first powered on for heating, and nitrogen is blown into the air vent and the vacuum pump is turned on. After 5 minutes, the first carbonization temperature of 1300°C is reached. The nitrogen enters the shell chamber after long-distance preheating through the volute-shaped guide device. Due to the small aperture of the pores, the gas outflow is not smooth. The gas accumulates in the chamber and gradually forms a high-pressure environment. Under the action of pressure, the air flow passes through each pore and is evenly ejected into the quartz tube at 360°, and the quartz tube is evenly filled with nitrogen. During the first carbonization, the fiber raw wire needs to be manually pulled to the wire collection device and wound with a wire 2.5 times the length of the carbonization furnace. The wire collection device roller rotation speed is set to 50r / min, and the wire release device roller rotation speed is 45r / min. The motor works and the fiber bundle begins to enter the carbonization furnace for carbonization; after the first carbonization, the polarity of the bipolar excitation power supply is changed to change the direction of the excitation current so that the DC motor with the excitation winding rotates counterclockwise, and the wire release and wire collection work are interchanged, and the fiber bundle turns the wire running direction. Raise the heating temperature of the silicon-molybdenum rod to 1350℃, and the second carbonization begins; after the second carbonization, the roller rotates clockwise, the wire release and wire collection work are interchanged, and the fiber bundle turns the wire running direction. Raise the heating temperature of the silicon-molybdenum rod to 1400℃, and the third carbonization begins; after the third carbonization, the roller rotates counterclockwise, the wire release and wire collection work are interchanged, and the fiber bundle turns the wire running direction. The heating temperature of the silicon-molybdenum rod is raised to 1450℃, and the fourth carbonization begins; after the fourth carbonization, the roller rotates clockwise, the work of releasing and collecting the wire is exchanged, and the fiber tow changes the direction of wire feeding. The heating temperature of the silicon-molybdenum rod is raised to 1500℃, and the fifth carbonization begins. The carbon fiber tow undergoes five carbonizations and the temperature in the furnace rises in a step-by-step manner. The collecting device rewinds this section of carbonized carbon fiber and rewinds a new section of fiber tow, and the heating temperature of the silicon-molybdenum rod returns to 1350℃. In addition, during the carbonization process, the airflow through the pipeline gradually narrows, forming a narrow tube effect to accelerate the airflow speed and discharge the smoke generated by carbonization through the sewage hole and the exhaust pipe under the action of the exhaust fan. At the same time, in order to prevent the smoke from accumulating above the shell chamber, the three silicon-molybdenum rods strengthen the heat of the smoke and help it move upward and discharge it out of the furnace, realizing repeated carbonization and cleaning in one.

Claims

1. The new carbonization furnace with integrated repeatable carbonization and cleaning is composed of a shell, a volute-shaped guide device, a quartz tube, a silicon-molybdenum rod, a wire-releasing / receiving device, an exhaust pipe, an exhaust fan and a power supply: The outer shell is a cylindrical hard chamber, one end of which is loaded with a volute-shaped guide device, and the upper end has a hole reserved for the exhaust pipe to connect the exhaust fan; the volute-shaped guide device rotates from the edge of the outer shell to the inner radius and gradually shrinks to connect with the quartz tube, and a raised air vent is provided at the edge. The protective gas is blown into the chamber from the air vent, rotates around the volute-shaped pipe into the chamber, and in the process, the heat radiated by the silicon-molybdenum rod is used for long-range preheating, thereby reducing the temperature difference between the protective gas and the quartz tube and preventing heat loss; the connection between the volute-shaped guide device and the quartz tube is provided with a number of fine air holes around the pipe, so that the preheated protective gas is sprayed into the quartz tube at 360 degrees, and the small aperture limits the air flow rate so that the gas The flow output is less than the input, and the gas is continuously accumulated in the chamber to form a high-pressure environment in the quartz tube. Under the action of pressure, the flow rate of gas ejected from each air hole is slightly different, so that the protective gas is evenly filled in the quartz tube; the diameter of the quartz tube gradually decreases in a smooth curve from the connection with the volute-shaped guide device, and then extends to the other end of the quartz tube in parallel with the minimum diameter. The minimum diameter is not less than the diameter of the fiber bundle. The structure of the gradually decreasing pipeline is constructed to increase the gas flow rate by utilizing the narrow tube effect, and the waste and exhaust gas generated by carbonization are transported to the other end of the pipeline along the gas flow direction and extracted through the exhaust pipeline. In order to discharge the smoke and exhaust gas generated by carbonization more smoothly, a pipe is wound around the end of the quartz tube close to the exhaust pipeline. There are holes around the channel; silicon-molybdenum rods are distributed in the chamber between the shell and the quartz tube and connected to the shell. The silicon-molybdenum rods are U-shaped and can be bent multiple times to increase the length to provide heat for preheating the protective gas and carbonizing the fiber bundles; the flue gas generated by carbonization moves upward due to the heat. In order to prevent the flue gas from accumulating above the shell chamber, a number of silicon-molybdenum rods are respectively arranged on the upper and lower parts of the quartz tube. On the premise that the heat released by all the quartz tubes in the furnace reaches the temperature required for this carbonization, the total heat generated by the silicon-molybdenum rods above is guaranteed to be 110% of the total heat generated by the silicon-molybdenum rods below, so as to strengthen the heating of the gas above the chamber and form a slight convection in the vertical direction, which is conducive to the smooth discharge of the flue gas above the furnace; the silicon-molybdenum rod electric heating elements can be used separately, and the first Before entering the carbonization furnace for the first time, the heating temperature of the silicon-molybdenum rod is controlled to be 1300℃; after the first carbonization is completed, the fiber bundle turns its traveling direction and enters the carbonization furnace for the second time, and the heating temperature of the silicon-molybdenum rod is adjusted to 1350℃; after the second carbonization is completed, the fiber bundle turns its traveling direction and enters the carbonization furnace for the third time, and the heating temperature of the silicon-molybdenum rod is adjusted to 1400℃; after the third carbonization is completed, the fiber bundle turns its traveling direction and enters the carbonization furnace for the fourth time, and the heating temperature of the silicon-molybdenum rod is adjusted to 1450℃; after the fourth carbonization is completed, the fiber bundle turns its traveling direction and enters the carbonization furnace for the fifth time, and the heating temperature of the silicon-molybdenum rod is adjusted to 1500℃, so that the carbonization temperature in the furnace rises step by step, and high and low temperature carbonization is repeated;The wire laying / collecting device is a roller rotating collector, which is located on both sides outside the carbonization furnace and keeps aligned in the horizontal direction. The rotation speed of the roller is controlled by independent motors on both sides. The rotation speed of the front roller in the wire feeding direction needs to be slightly greater than that of the rear roller to increase the tension on the fiber bundle to prevent the fiber bundle from slipping or being rolled away by the rear roller. After the same device completes the wire laying or collecting work, it can take on another work by changing the rotation direction of the motor; when the fiber bundle with a length of 2-3 times the length of the carbonization furnace is wound on the collection shaft, the rotation direction of the roller is changed to prevent the fiber bundle on the collection shaft from being too short to undergo repeated carbonization and the fiber bundle from being too long to undergo repeated carbonization unevenly. ;

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