JP4493468B2 - Flameproofing furnace - Google Patents

Description

  The present invention relates to a flameproofing furnace for flameproofing a fiber that is a precursor of a carbon fiber, and more particularly to a flameproofing furnace for a precursor fiber suitable for producing a carbon fiber excellent in productivity.

  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. 7 is a schematic front sectional view showing an example of a conventional flameproofing furnace. In FIG. 7, reference numeral 112 denotes a flameproofing furnace, which runs in a heat treatment chamber 114 while forming a strand group (path) in which a large number of strands 116 are horizontally arranged. The strand 116 forming this path is folded back by a predetermined set of folding rollers (not shown) disposed outside the heat treatment chamber 114 and repeatedly supplied to the heat treatment chamber 114.

  By passing a high-temperature oxidizing gas through the path in the vertical direction, the oxidation reaction of the strands 116 can be promoted, and the reaction heat of the strands 116 can be removed to produce flame-resistant fibers.

  The heat treatment chamber 114 has an upper flow path (hot air discharge side flow path) 118 formed above it and a lower flow path (hot air suction side flow path) 120 formed below it. In addition, the heat treatment chamber 114 has a hot air circulation path 122 by providing a partition wall 124 on one side in the width direction of the strand 116 running in the same chamber.

  An outer wall 126 that separates the heat treatment chamber 114 from the outside of the furnace is formed on the side of the heat treatment chamber 114 that faces the hot air circulation path 122.

  A heater 128 is provided in the hot air circulation path 122. The hot air heated by the heater 128 is sent from the upper flow path 118 of the heat treatment chamber 114 into the heat treatment chamber 114 by the hot air circulation means 130 such as a fan, where the strand 116 that forms the path and travels is flameproof. Is processed. Next, the hot air returns to the hot air circulation path 122 through the lower flow path 120 and is repeatedly heated by the heater 128 through the hot air circulation path 122.

  Increasing the amount of the strands 116 that are run to increase the productivity of the flame-resistant fiber and increasing the width thereof will increase the width of the heat treatment chamber 114 accordingly.

  However, as the width of the heat treatment chamber 114 increases, the width of the upper flow path 118 also increases, and the difference between the hot air temperature and the hot air wind speed increases between the partition wall 124 side and the outer wall 126 in the upper flow path 118. Moreover, on the partition 124 side and the outer wall 126 in the heat treatment chamber 114, the ventilation resistance of the path is added, and the difference between the hot air temperature and the hot air wind speed is further increased.

  The hot air also circulates this to heat the strands and simultaneously remove the heat.

Therefore, the temperature distribution of the strands in the heat treatment chamber 114 is non-uniform in the flameproofing treatment furnace 112 having a wide width of the heat treatment chamber 114 of 3 m or more. As a result, there is a problem in that the reaction rate is lowered at a portion where the strand temperature is low, and the productivity is lowered. In the portion where the temperature of the strand is high, the fiber is cut by heat storage, and the cut fiber is entangled with the fiber of the other strand, which causes a problem of increasing trouble.
JP 2001-288623 A (pages 2 to 3)

  While various studies have been made by the present inventor to solve the above problems, a flameproofing treatment in which a lower flow path of the heat treatment chamber is divided by a partition plate from the partition wall side to the outer wall side to form a plurality of divided flow paths. By using a furnace, controlling the flow rate of hot air in the heat treatment chamber and supplying hot air so that the strands running in the heat treatment chamber have a uniform temperature, it is known that stable production of flame resistant fibers can be achieved, The present invention has been completed.

  Therefore, the object of the present invention is to provide a flameproof heat treatment furnace that solves the above-mentioned problems, more specifically, flameproofing treatment of precursor fiber strands can be performed uniformly, without reducing the quality. An object of the present invention is to provide a flameproof heat treatment furnace capable of improving productivity.

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

  [1] A heat treatment chamber in which hot air is sent in the vertical direction of the precursor fiber strand running horizontally in the furnace to make the strand flameproof, an upper flow path formed above the heat treatment chamber, and a lower portion formed below the heat treatment chamber A flameproof furnace having a flow path and a hot air circulation path communicating the upper flow path and the lower flow path, wherein at least one of the lower flow path and the upper flow path is from the hot air circulation path side in the heat treatment chamber A flameproofing treatment furnace comprising a divided flow path divided into a plurality of parts toward an outer wall facing the hot air circulation path, and the heat treatment chamber and the hot air circulation path communicated with each other through the divided flow paths.

  [2] The flameproofing treatment furnace according to [1], wherein each of the divided flow paths has a damper for adjusting the hot air flow rate.

  [3] The flameproofing treatment furnace according to [1], wherein each of the divided flow paths has a breathable plate material for adjusting the amount of hot air.

  [4] The flameproofing treatment according to [1], including a hot air bypass route that communicates the upper flow path and the lower flow path outside the outer wall of the heat treatment chamber, and the hot air bypass path includes a damper for adjusting the amount of hot air flow. Furnace.

  Since the flameproofing furnace of the present invention is configured as described above, the temperature of the strands running in the heat treatment chamber becomes uniform, and stable production of flameproofing fibers can be achieved.

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

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

  In FIG. 1, reference numeral 2 denotes a flameproofing treatment furnace, and a large number of strands 6 are formed in the heat treatment chamber 4 to form a strand group (pass) arranged in a horizontal plane (a plane perpendicular to the paper surface). . The strands 6 forming this path are folded back by a predetermined set of folding rollers (not shown) disposed outside the heat treatment chamber 4 and repeatedly supplied to the heat treatment chamber 4 to form a plurality of stages. Yes.

  In the heat treatment chamber 4, an upper flow path (hot air discharge side flow path) 8 is formed above, and a lower flow path (hot air suction side flow path) 10 is formed below. In the heat treatment chamber 4, a hot air circulation path 12 is formed on one side in the width direction of the strand 6 running in the same chamber.

  On the hot air circulation path 12 side of the heat treatment chamber 4, a partition wall 14 that separates the heat treatment chamber 4 and the hot air circulation path 12 is formed. An outer wall 16 that separates the heat treatment chamber 4 and the outside of the furnace is formed on the opposite side of the heat treatment chamber 4 from the hot air circulation path 12.

  Hot air heated by the heater 18 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 20 such as a fan, and travels by forming the path here. The strand 6 is flameproofed. Next, the hot air returns to the hot air circulation path 12 through the lower flow path 10 and is repeatedly heated by the heater 18 through this.

  The lower flow path 10 is divided by a partition plate 26 having a vertical member 22 and a horizontal member 24 and having an L-shaped cross section, and a flow path (a) 28 through which hot air from the partition wall 14 of the heat treatment chamber 4 passes and a heat treatment chamber. Two divided flow paths are formed, which are composed of flow paths (b) 30 through which the four outer wall 16 side hot air passes.

  In addition, the strand running direction length of the partition plate 26 is formed to be equal to the strand running direction length of the heat treatment chamber 4.

  Using the flameproofing treatment furnace 2 configured as described above, the flow rate of hot air in the heat treatment chamber 4 is controlled, and the hot air is supplied so that the strands 6 running in the heat treatment chamber 4 have a uniform temperature, thereby making the flame resistant. Stable fiber production is possible.

  It should be noted that the partition plate 26 can adjust the amount of hot air in each flow path by adjusting the flow path length, flow path width, flow resistance, and the like in the divided flow path (a) 28 and the divided flow path (b) 30. It is preferable that the vertical direction member 22 and the horizontal direction member 24 have a movable structure.

  FIG. 2 is a schematic view showing another example of a front cross section in the flameproofing treatment furnace of the present invention.

  In the flameproofing treatment furnace 32 of this example, dampers 34 and 36 for adjusting the hot air flow rate are provided in the divided flow path (a) 28 and the divided flow path (b) 30, respectively. Thereby, ventilation resistance can be adjusted and the amount of hot air in each flow path can be adjusted.

  Since other configurations are the same as those in FIG. 1, the same reference numerals are given to the same portions and the description thereof is omitted.

  FIG. 3 is a schematic view showing still another example of a front cross section in the flameproofing treatment furnace of the present invention.

  In the flameproofing treatment furnace 42 of this example, the divided flow path (a) 28 and the divided flow path (b) 30 are respectively provided with breathable plate materials 44 and 46 for adjusting the hot air flow rate. As the air-permeable plate members 44 and 46, slit plates, nets, punching plates or the like whose opening degree is adjusted can be used. Thereby, ventilation resistance can be adjusted and the amount of hot air in each flow path can be adjusted.

  Since the other configuration is the same as that of FIG.

  FIG. 4 is a schematic view showing still another example of a front cross section in the flameproofing furnace of the present invention.

  In the flameproofing treatment furnace 52 of this example, a hot air bypass 54 that communicates the upper flow path 8 and the lower flow path 10 is provided outside the outer wall 16 of the heat treatment chamber 4. The hot air bypass circuit 54 is provided with a damper 56 for adjusting the amount of hot air passing therethrough. This facilitates temperature control of the strand 6 on the outer wall 16 side in the heat treatment chamber 4.

  Since the other configuration is the same as that of FIG.

  In each of the above examples, the lower flow path is divided into two. However, the present invention is not limited to this, and may be divided into any plural number, preferably 2 to 4, and in the above example, the divided flow path width is further increased. Although it is made equal, the divided flow path width of an arbitrary ratio may be used, and other appropriate modifications may be made unless the gist of the present invention is changed.

  Just as the lower flow path is divided into an arbitrary plurality, the upper flow path may be divided into an arbitrary plurality. That is, the flameproofing furnace of the present invention is obtained by dividing at least one of the lower flow path and the upper flow path into an arbitrary plurality.

  FIG. 5 is a schematic front sectional view showing an example of a flameproofing furnace in which not only the lower flow path but also the upper flow path is divided into two in the configuration of the example of FIG.

  In the flameproofing treatment furnace 62 of this example, the upper flow path is divided by a partition plate 68 having a vertical member 64 and a horizontal member 66 and having a Γ-shaped cross section, and hot air is supplied to the partition wall 14 side of the heat treatment chamber 4. Two divided flow paths are formed, which are a flow path (c) 70 and a flow path (d) 72 for supplying hot air to the outer wall 16 side of the heat treatment chamber 4.

  In addition, the strand running direction length of the partition plate 68 is also formed to be equal to the strand running direction length of the heat treatment chamber 4, similarly to the strand running direction length of the partition plate 26.

  The divided flow path (c) 70 and the divided flow path (d) 72 are provided with dampers 74 and 76 for adjusting the hot air flow rate, respectively. Thereby, ventilation resistance can be adjusted and the amount of hot air in each flow path can be adjusted.

  In order to make it easy to adjust the amount of hot air supplied to each of the divided flow paths (c) 70 and 72 (d) 72, the hot air circulation means 78 is installed near the center of the hot air circulation path 12. Is preferred.

  Since other configurations are the same as those in FIGS. 1 and / or 2, the same portions are denoted by the same reference numerals, and the description thereof is omitted.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

Example 1
The flame resistant fiber and precursor fiber of the raw material for producing carbon fiber were subjected to a flame resistant treatment in heated air using a flame resistant furnace shown in FIG. 6 to obtain a flame resistant fiber.

  FIG. 6 is a schematic front sectional view showing an example of a flameproofing furnace in which the lower flow path is divided into three in the configuration of the example of FIG.

  In the flameproofing treatment furnace 82 of this example, the lower flow path 10 includes a partition wall 14 side partition plate 88 having a L-shaped cross section including a vertical member 84 and a horizontal member 86, a vertical member 90, and a horizontal member 92. And a flow path (e) 96 through which the partition wall 14 side hot air of the heat treatment chamber 4 passes, and a flow through which the heat flow of the outer wall 16 side of the heat treatment chamber 4 passes. Three divided flow paths are formed which are composed of the path (g) 100 and the intermediate flow path (f) 98 therebetween.

  The divided flow path (e) 96, the divided flow path (f) 98, and the divided flow path (g) 100 are provided with dampers 102, 104, and 106 for adjusting the hot air flow rate, respectively. The width of each divided flow path is such that the distance X between the partition wall 14 and the vertical member 84 is 1.4 m, the distance Y between the vertical member 84 and the vertical member 90 is 1.4 m, and the vertical member 90 and the outer wall 16 The distance Z is 1.4 m.

  The length, width, and height of the heat treatment chamber 4 are 12 m, 4.2 m, and 1.6 m, respectively. The number of turns by the turn-back roller is 7 passes. This path is composed of 400 strands arranged in a horizontal plane, and this strand is composed of 24,000 precursor fibers bundled together.

  Since the other configuration is the same as that of FIG.

  When hot air having a temperature of 250 ° C. is circulated at the outlet of the hot air circulation means 20 and the opening degree of the dampers 102, 104, 106 is adjusted to adjust the amount of hot air in each divided flow path, the unit flow rate at the divided flow path inlet section is determined. The flow rate per unit area (wind speed) is 1.2 m / second for the flow path (e) 96, 1.2 m / second for the flow path (f) 98, and 1.2 m / second for the flow path (g) 100. The temperature showed a uniform distribution of 251 ° C. at the point E on the partition wall 14 side, 250 ° C. at the point F near the center, and 250 ° C. at the point G on the outer wall 16 side, and stable production of flame resistant fibers was achieved.

Comparative Example 1
A flameproofing treatment was performed in the same manner as in Example 1 except that the conventional flameproofing furnace shown in FIG.

  In the flameproofing treatment furnace 112 of this example, the divided flow path is not formed in the lower flow path 120, but the divided flow path (e), the divided flow path (f), and the divided flow path (g) in FIG. 7 is 0.8 m / sec, 1.2 m / sec, and 1.6 m / sec, respectively, and the temperature of the strand is 254 ° C. at the point E on the partition wall 124 side. The distribution was uneven at 250 ° C. at the point F and 248 ° C. at the point G on the outer wall 116 side, the fiber was cut near the partition wall 124 side, and the production of the flameproof fiber was unstable.

It is the schematic which shows an example of the front cross section in this invention flameproofing processing furnace. It is the schematic which shows the other example of the front cross section in this invention flameproofing processing furnace. It is the schematic which shows the further another example of the front cross section in this invention flameproofing processing furnace. It is the schematic which shows the further another example of the front cross section in this invention flameproofing processing furnace. It is a schematic front sectional view showing an example of the flameproofing furnace of the present invention in which a lower flow path and an upper flow path are divided into two. It is a schematic front sectional drawing which shows an example of this invention flameproofing processing furnace which divided the downward flow path into three. It is a schematic front sectional view showing an example of a conventional flameproofing treatment furnace.

Explanation of symbols

2, 32, 42, 52, 62, 82, 112 Flameproofing furnace 4, 114 Heat treatment chamber 6, 116 Strand 8, 118 Upper flow path 10, 120 Lower flow path 12, 122 Hot air circulation path 14, 124 Bulkhead 16, 126 Outer wall 18, 128 Heater 20, 78, 130 Hot air circulation means 22, 64, 84, 90 Vertical member 24, 66, 86, 92 Horizontal member 26, 68, 88, 94 Partition plate 28 Split flow path (a)
30 division flow path (b)
34, 36, 56, 74, 76, 102, 104, 106 Damper 44, 46 Breathable plate material 70 Split flow path (c)
72 Divided flow path (d)
96 Divided flow path (e)
98 Divided flow path (f)
100 Divided flow path (g)
E, F, G Strand temperature measurement point X, Y, Z Width of split flow path

Claims (5)

A heat treatment chamber in which hot air is sent in the vertical direction of the precursor fiber strand running horizontally in the furnace to make the strand flameproof, an upper flow path formed above the heat treatment chamber, and a lower flow path formed below the heat treatment chamber; A flameproofing furnace having a hot air circulation path communicating with the upper flow path and the lower flow path, wherein the heat treatment chamber has a width of 3 m or more, and at least one of the lower flow path and the upper flow path is From the hot air circulation path side in the heat treatment chamber to the outer wall side facing the hot air circulation path, it is composed of divided flow paths divided into a plurality of partition plates having a L-shaped cross section consisting of vertical members and horizontal members , these by communicating the heat treatment chamber and the hot air circulation path by dividing flow path, oxidization treatment furnace adjust the hot air volume flowing through the heat treatment chamber in the vertical direction in each divided flow paths. The flameproofing treatment furnace according to claim 1, wherein each of the divided flow paths has a damper for adjusting the amount of hot air. The flameproofing treatment furnace according to claim 1, wherein each of the divided flow paths has a breathable plate material for adjusting the amount of hot air. 2. The flameproofing treatment furnace according to claim 1, further comprising a hot air bypass that communicates the upper flow path and the lower flow path outside the outer wall of the heat treatment chamber, and the hot air bypass has a damper for adjusting the amount of hot air. The flameproofing treatment furnace according to claim 1, which has a structure in which a vertical member and a horizontal member of the partition plate are movably provided and the flow of hot air is adjusted by adjusting the flow channel width.

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