JP2006057222A - Flame resisting treatment furnace and method for flame resisting treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flame resisting treatment furnace for a carbon fiber precursor strand, keeping the circulating air flow in the furnace at a constant level and effective for improving the productivity of flame-resistant fiber. <P>SOLUTION: The flame resisting treatment furnace 2 is composed of a heat-treatment chamber 4 to supply hot air perpendicular to a precursor fiber strand 5 horizontally traveling in the furnace to perform the flame resisting treatment of the strand 5, an upper flow channel 8 formed above the heat-treatment chamber 4, a lower flow channel 10 formed under the heat-treatment chamber and a hot air circulation channel 12 connecting the upper channel to the lower channel. The hot air circulation channel contains foreign material removing means 18a, 18b, a hot air circulation means 16 and a hot air velocity sensor 20. The furnace 2 is further provided with a controller 22 receiving the detection signal of the hot air velocity sensor 20, converting to an output control signal of the hot air circulation means 16 and transmitting the converted signal to the hot air circulation means 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flameproofing furnace and a flameproofing method for flameproofing a fiber that is a precursor of carbon fiber, and more specifically, a flameproofing furnace and flameproofing of a precursor fiber suitable for producing carbon fiber having excellent productivity. The present invention relates to a processing method.

  In the carbon fiber manufacturing process, the precursor fiber is made flame resistant, and the obtained flame resistant fiber is carbonized to form carbon fiber. As a method for making the precursor fiber flame resistant, there is a method in which hot air is circulated in an oxidizing atmosphere and the precursor fiber is allowed to pass therethrough (see, for example, Patent Document 1). In this flameproofing method, the precursor fibers are usually fed into a flameproofing furnace as bundled strands.

  FIG. 2 is a schematic front sectional view showing an example of a conventional flameproofing furnace. In FIG. 3, reference numeral 32 denotes a flameproofing furnace, and a plurality of strands 35 are formed in a heat treatment chamber 34 to form a strand group (pass) arranged in a horizontal plane. The strands forming this path are folded back by a predetermined set of folding rollers (not shown) disposed outside the heat treatment chamber 34 and repeatedly supplied to the heat treatment chamber 34 to form a plurality of stages of passes. .

  By passing a high-temperature oxidizing gas through the path, it is possible to promote the oxidation reaction of the strands and remove the reaction heat of the strands to produce flame-resistant fibers.

  Side walls 36a and 36b are provided on both sides of the strand running in the heat treatment chamber 34 in the width direction so as to separate the inside from the outside. A hot air circulation path 42 that communicates the upper flow path 38 and the lower flow path 40 of the heat treatment chamber 34 is provided outside the one side wall 36 a across the space 44.

  Hot air heated by a heater (not shown) provided in the hot air circulation passage 42 is sent from the upper flow path 38 of the heat treatment chamber 34 into the heat treatment chamber 34 by the hot air circulation means 46 such as a fan, and forms the path here. Then, the running strand is flame-resistant. Next, the hot air passes through the lower flow path 40 and enters the hot air circulation path 42, and is repeatedly circulated through the heater to the heater.

  While hot air circulation is repeated in the flameproofing treatment of the strands, foreign matter such as strands and powder derived from the strand accumulates in the hot air, and the flameproof fibers are contaminated. In order to prevent this, it is conceivable to provide a foreign matter removing means such as a wire mesh in the hot air circulation path 42.

  However, when the foreign matter removing means is provided in the hot air circulation path 42, the resistance differential pressure before and after the foreign matter removing means is increased while the foreign matter is repeatedly deposited on the hot air circulation path 42, and the circulating air volume in the furnace is lowered, thereby stabilizing the strand. Flameproofing cannot be performed.

For this reason, the foreign matter removing means is frequently replaced with one that has been regenerated by removing the foreign matter, but during operation, the resistance differential pressure before and after the foreign matter removing means fluctuates violently, so frequent rest Will do. As a result, the productivity of the flameproof fiber is reduced.
JP 2001-288623 A (pages 2 to 3)

  While the present inventor has made various studies in order to solve the above problems, it has been found that a continuous operation can be stably performed by keeping the in-furnace circulation air flow of the flameproofing furnace constant.

  In addition, if this flameproofing furnace is used, the amount of circulating air in the furnace, which has decreased due to an increase in the resistance differential pressure before and after the foreign matter removing means, can be exchanged even during operation of the foreign matter removing means in the hot air circulation path. The present inventor has learned that it is possible to return to the in-furnace circulating air flow, and the present invention has been completed.

  Accordingly, an object of the present invention is to provide a flameproofing furnace that solves the above problems and a method for flameproofing precursor fibers using the furnace.

  The present invention for achieving the above object is described below.

  [1] Formed below the heat treatment chamber, a heat treatment chamber in which hot air is sent in the vertical direction of the strands of the precursor fibers running horizontally in the furnace to make the strands flame resistant, an upper channel formed above the heat treatment chamber, and a heat treatment chamber Provided in a hot air circulation path, a hot air circulation path communicating with the lower flow path, the upper and lower flow paths, a foreign matter removing means provided in the hot air circulation path, a hot air circulation means provided in the hot air circulation path, and a hot air circulation path A flameproofing treatment furnace having a hot air wind speed sensor and a control unit, wherein the control unit controls the blowing amount of the hot air circulating means to a predetermined amount based on a detection signal of the hot air wind speed sensor.

  [2] A method for flameproofing a precursor fiber using the flameproofing furnace described in [1], wherein the amount of hot air in the hot air circulation path is detected by a hot air wind speed sensor and controlled based on the value of the detection signal. A flameproofing method for keeping the air flow rate of the hot air circulating means constant by converting the output control signal of the hot air circulating means in the unit and controlling the output of the hot air circulating means with the output control signal.

  [3] A method for flameproofing a precursor fiber using the flameproofing furnace described in [1], wherein the amount of air in the hot air circulation passage passing through the foreign matter removal means is replaced with the foreign matter removal means in the hot air circulation passage. A flameproofing treatment method for controlling the air volume in the hot air circulation path within a predetermined range.

  [4] A flameproofing method for a precursor fiber using the flameproofing furnace according to [1], wherein a pitot tube is used as a hot air wind speed sensor for detecting the amount of air in the hot air circulation path.

  Since the flameproofing furnace of the present invention is configured as described above, the output of the hot air circulating means is controlled in accordance with the fluctuation of the circulating air volume in the furnace, and the circulating air volume in the furnace is kept constant. Further, according to the flameproofing treatment furnace of the present invention, the amount of circulating air in the furnace, which has decreased due to an increase in the resistance differential pressure before and after the foreign matter removing means, can be exchanged even while the foreign matter removing means in the hot air circulation path is in operation. The amount of circulating air in the furnace within the range can be returned, and the productivity of the flameproof fiber can be improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic front sectional view showing an example of the flameproofing furnace of the present invention.

  In FIG. 1, reference numeral 2 denotes a flameproofing furnace, and a large number of strands 5 travel in the heat treatment chamber 4 while forming strand groups (paths) arranged in a horizontal plane (surface perpendicular to the paper surface). . The strands 5 forming this path are folded back by a predetermined set of folding rollers (not shown) arranged outside the heat treatment chamber 4 and repeatedly supplied to the heat treatment chamber 4 to form a plurality of stages. Yes.

  Side walls 6a and 6b are provided on both sides of the heat treatment chamber 4 to separate the inside and the outside. A hot air circulation path 12 that communicates the upper flow path 8 and the lower flow path 10 of the heat treatment chamber 4 is provided across the space 14 outside the one side wall 6a.

  The hot air supply means includes an upper flow path 8, a lower flow path 10, and a hot air circulation path 12. The space portion 14 may be omitted, but the space portion 14 is present when the temperature in the heat treatment chamber 4 is adjusted by heating or cooling not only from the outside of the side wall 6b but also from the outside of the side wall 6a. Is preferred.

  Hot air heated by the heater 15 provided in the hot air circulation path 12 is sent into the heat treatment chamber 4 from the upper flow path 8 of the heat treatment chamber 4 by the hot air circulation means 16 such as a fan, and travels by forming the path here. The strand 5 is subjected to flameproofing treatment. Next, the hot air enters the hot air circulation path 12 through the lower flow path 10, and is repeatedly circulated through the heater 15.

  In the flameproofing furnace 2, a foreign matter removing means 18 a and a hot air wind speed sensor 20 are provided before and after the hot air circulation means 16 in the hot air circulation path 12. Outside the hot air circulation path 12, it receives a wind speed detection signal from the hot air wind speed sensor 20, converts it into an output control signal of the hot air circulation means 16, and sends it to the hot air circulation means 16. A control unit 22 is provided that operates so as to keep the hot air flow rate at a predetermined value. As a result, the air volume in the heat treatment chamber 4 is also maintained at a predetermined value.

  By providing the foreign matter removing means 18a in the hot air circulation path 12, even if hot air circulation is repeated in the flameproofing treatment of the strand 5, accumulation of foreign matters such as fluff and powder in the hot air and contamination of the flameproof fiber are not caused. It is prevented. As the foreign matter removing means, a porous plate such as a wire mesh or a punching plate can be used, and the opening is preferably 10 to 100 mesh.

  In the flameproofing method using the flameproofing furnace of this example, the hot air flow rate in the hot air circulation path 12 is detected by the hot air wind speed sensor 20, and the control unit 22 uses the value of the detection signal as a reference. The output is converted to an output control signal of the hot air circulating means 16 corresponding to the change in the air volume, and the output of the hot air circulating means 16 is controlled. Therefore, even if the resistance differential pressure before and after the foreign matter removing means 18a increases as the hot air circulation is repeated. The air volume in the hot air circulation path is kept constant within a predetermined range, and the flameproof fiber is stably produced.

  The amount of hot air in the hot air circulation path 12 is preferably 2 to 10 m / sec, and more preferably 4 to 8 m / sec in terms of the wind speed in the hot air wind speed sensor 20. It is preferable to use a Pitot tube as a hot air wind speed sensor for detecting the air volume in the hot air circulation path.

  In FIG. 1, reference numeral 18b denotes a regenerated foreign matter removing means from which foreign matter has been removed or an unused foreign matter removing means. It is preferable to replace the foreign matter removing means 18a with the foreign matter removing means 18b when the hot air circulation is repeated and the wind speed in the hot air wind speed sensor 20 becomes 2 m / second, preferably 4 m / second.

  By exchanging the foreign matter removing means, the air volume in the hot air circulation path can be returned to the predetermined range. The foreign matter removing means replacement method will be described step by step in FIG. 1. Two stages for setting the foreign matter removing means are provided upstream of the hot air circulating means 16 in the hot air circulation path 12.

  On the upper stage, foreign matter removing means 18a is set. The foreign substance removing means 18b is set at the lower stage. At this time, as the foreign matter accumulates in the foreign matter removing means 18a, the resistance differential pressure before and after the foreign matter removing means 18a gradually increases, and the amount of air in the hot air circulation path decreases momentarily. The decreasing amount of air in the hot air circulation path is detected by the hot air wind speed sensor 20. Based on the value of the detection signal, the control unit 22 converts the output to the output control signal of the hot air circulation means 16 according to the decrease in the air volume in the hot air circulation path, and the output of the hot air circulation means 16 is controlled. When the hot air circulation means 16 is a fan, the number of rotations of the fan is increased, and the air volume in the hot air circulation path is restored within the predetermined range.

  Next, the foreign matter removing means 18b is attached to the lower stage of the set. Next, the foreign matter removing means 18a is removed. At this time, the pressure difference in the foreign matter removing means 18a is reduced to the differential pressure in the foreign matter removing means 18b, and the amount of air in the hot air circulation path increases momentarily. The increased hot air circulation path air volume is detected by the hot air wind speed sensor 20. Based on the value of this detection signal, the control unit 22 converts the output to the output control signal of the hot air circulation means 16 according to the increase in the amount of air in the hot air circulation path, and the output of the hot air circulation means 16 is controlled. When the hot air circulation means 16 is a fan, the rotational speed of the fan decreases, and the air volume in the hot air circulation path is returned to the predetermined range.

It is a schematic front sectional view showing an example of the flameproofing treatment furnace of the present invention. It is a schematic front sectional view showing an example of a conventional flameproofing furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Flame resistance treatment furnace 4 Heat processing chamber 5 Strand 6a, 6b Side wall 8 Upper flow path 10 Lower flow path 12 Hot air circulation path 14 Space part 15 Heater 16 Hot air circulation means 18a, 18b Foreign material removal means 20 Hot air wind speed sensor 22 Control part 32 Flame resistance Chemical treatment furnace 34 Heat treatment chamber 35 Strand 36a, 36b Side wall 38 Upper flow path 40 Lower flow path 42 Hot air circulation path 44 Space portion 46 Hot air circulation means

Claims (4)

A heat treatment chamber that sends hot air in the vertical direction of the strands of precursor fibers that run horizontally in the furnace to make the strands flame resistant, an upper flow path formed above the heat treatment chamber, and a lower flow path formed below the heat treatment chamber A hot air circulation path communicating with the upper and lower flow paths, a foreign matter removing means provided in the hot air circulation path, a hot air circulation means provided in the hot air circulation path, and a hot air wind speed sensor provided in the hot air circulation path And a control unit, and the control unit controls the blowing amount of the hot air circulating means to a predetermined amount based on a detection signal of the hot air wind speed sensor. A method for flameproofing a precursor fiber using the flameproofing furnace according to claim 1, wherein the amount of hot air in the hot air circulation path is detected by a hot air wind speed sensor, and a hot air is detected by a control unit based on the value of the detection signal. A flameproofing method for maintaining a constant air flow rate of the hot air circulating means by converting to an output control signal of the circulating means and controlling the output of the hot air circulating means with the output control signal. A method for flameproofing a precursor fiber using the flameproofing furnace according to claim 1, wherein the amount of air in the hot air circulation path passing through the foreign matter removal means is replaced with the foreign matter removal means in the hot air circulation path. A flameproofing method for controlling the air volume in the hot air circulation path within a predetermined range. A flameproofing method for a precursor fiber using the flameproofing furnace according to claim 1, wherein a pitot tube is used as a hot air velocity sensor for detecting the amount of air in the hot air circulation path.

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