JPH01192825A - Apparatus for making flame-resistant - Google Patents

Abstract

PURPOSE:To perform uniform heat-treatment of fiber even by using a fluidized layer having low height, by fluidizing heat-medium particles deposited on a dispersion plate with gas blasted through the holes of the dispersion plate, and passing a number of precursor fibers through the fluidized layer in a specific arrangement. CONSTITUTION:Heat-medium particles are deposited on dispersion plates 8, 8' in a flame-resistant treatment furnace 1 and are fluidized by oxidizing gas blasted upward through the holes of the dispersion plates 8, 8'. A group of precursor fibers 101 is continuously passed through the obtained fluidized layer to effect the flame-resistant treatment of the fiber 101. In the above apparatus for the flame-resistant treatment, the precursor fibers are vertically arranged into plural sections and placed at a height of 5-500mm from the dispersion plates 8, 8' by guiding means 41, 42, 43, 44 and, at the same time, heating means 6, 7 are placed in a gas channel before the oxidizing gas enters into the fluidized layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a flame-retardant device for precursor fibers, and particularly to the structure of a flame-retardant device using a fluidized bed.

[Prior art] Flame-resistant binding cords are usually made of polyacrylonitrile (hereinafter referred to as PA).
Precursor fibers made of organic polymers such as N (abbreviated as J) type fibers, recycled cellulose fibers, phenolic fibers, pitch fibers, etc. are heated in a light heavy air or other oxidizing residue atmosphere for 20 minutes.
It is obtained by making it flame resistant at 0 to 300'C (generally called infusibility for pitch fibers, which is further treated at a high temperature of about 450'C). Next, this was heated at 800-2000° in an inert gas atmosphere such as nitrogen or argon.
It can be carbonized with C to make carbon fiber, and it can also be carbonized with
Graphitization is also carried out in an inert gas atmosphere at a temperature of 0.degree. C. or higher to produce graphite fibers with even higher elastic modulus.

The above-mentioned flameproofing process is a reaction involving oxidation and cyclization, and the higher the temperature, the higher the reaction rate and the shorter the treatment time required for flameproofing. However, because the reaction is accompanied by exothermic heat,
If the processing temperature is too high or if a large number of precursor fibers are packed at a high density, reaction heat will accumulate within the fibers, causing fusion between single yarns, ignition, and yarn breakage. Therefore, in order to increase the production efficiency of the flame-retardant process, it is important to use a process that efficiently removes the heat generated by the reaction of the fibers while treating the fibers at as high a temperature as possible.

Conventional flame-retardant methods that meet these objectives include blowing hot air onto the precursor fibers or intermittently contacting them with a heated solid surface.
A well-known method is to perform flameproofing treatment for 0 to 120 minutes, with the latter taking about 20 minutes.

However, in the above-mentioned known method, there is a problem that it is difficult to significantly shorten the processing time because there are limits to the heating efficiency of the precursor fiber and the removal efficiency of reaction heat, which are moderately CJ. , and when the denier of the precursor fiber becomes large, it becomes difficult to effectively heat or remove heat inside the fiber bundle, so there is a problem that it is difficult to increase the denier of the precursor fiber and improve the processing density11. In addition, in the method of blowing hot air described above, the hot air is usually circulated and only a part of the used hot air is exhausted from the viewpoint of energy saving, but it is difficult to achieve the desired amount of heating and heat removal. This requires a large amount of hot air circulation, and there is also the problem that the equipment, the capacity of the heater provided in the circulation system, and the amount of hot air used are considerably large.

To address these problems, we have developed a method to improve the heating and heat removal efficiency of precursor fibers, shorten the processing gap, and significantly reduce the amount of hot air used. There is a way to process it. Japanese Patent Publication No. 44-25375 discloses that filaments 1 to 1 of polyacrylonitrile are heated in an oxidizing atmosphere to a temperature in the range of 200 to 30° C. in a second step (J). In the process of producing filamentary carbon by carbonizing it at a temperature of around 1000'C in an active atmosphere, the -1 process of heating in an oxidizing atmosphere is performed.
For this reason, a method has been proposed that is characterized by being carried out in a fluid bed of a chemically inert solid heat conductor.

In addition, as a flame-retardant method including at least one step of etching treatment in a fluidized bed, Japanese Patent Publication No. 47/18896
No. Publication or publicly known.

However, the flame-retardant treatment time in the first method is 0.
．． 5 to 1 hour, in the second method, prei+:i
+ For oxidized T culms, d3 is about 7 hours, and for post-oxidation step 10
This method requires ~15 minutes, and cannot be said to be advantageous in terms of flame resistance compared to the above-mentioned method using a heated gas atmosphere or contact heat transfer.

In order to solve this problem, the present applicant previously proposed a method in which precursor fibers are heat-treated in a fluidized bed on a dispersing means to make them flame resistant. Using solid particles as a heating medium, a fluidized bed is formed on the dispersion means by setting the depth H [771] of the heating medium particles at rest from the upper surface level to the dispersion means in the following range, and in the fluidized bed, the precursor is A method for making precursor fibers flame resistant has been proposed, which is characterized by heat-treating the fibers at 200 to 550°C.

20M f /(ρ1/cpA)<tr<500/
ρυHere, Mf: weight of precursor fibers present in the fluidized bed [K3]ρ1
/: Bulk density of heating medium particles [Kg/TrL3] CP: Specific heat of heating medium particles [K c a I'/Ky°C] A: Fluidized area of fluidized bed [m2].

[Problems to be Solved by the Invention] = 5 = However, the above-mentioned flame-retardant device (J) using a fluidized bed still has the following technical problems.

In general, as a heating structure of a fluidized bed of heat transfer particles, the 13th
A device as shown in FIG. 1 or FIG. 14 is known. 1st
Figure 3 shows an external hll heating type device, with air supply hole 9
The heat medium particle fluidized bed 5, which is fluidized by the gas sent through the dispersion plate 8, is heated by a heating means 70 provided on the outside of the device.
It is heated by heat transfer from

FIG. 14 shows an internal heating type device, in which the fluidized bed 5
is heated by directly contacting heating means 71 disposed within the fluidized bed 5.

If such a known fluidized bed heating structure is applied as is to a flameproofing device, the following problems will arise.

In the external heating type shown in FIG. 13, the efficiency of heat transfer to both sides of the fluidized bed 5 and the central part are different, making it difficult to ensure temperature uniformity in the width W direction of the fluidized bed. It is difficult to maintain a predetermined flame-retardant treatment temperature over the entire width. This problem becomes more pronounced as the width W increases, so there is a limit to how wide the fluidized bed can be made. The internal heating type shown in FIG. 14 has similar problems. In other words, there is no problem if the heating means 71 are evenly arranged in the width W direction of the fluidized bed 5, but
In this case, the fluidization of the heating medium particles is significantly inhibited and the effective processing volume is reduced, so that the heating means 71 must be placed on both sides of the fluidized bed as shown in the figure. Temperature non-uniformity occurs between the vicinity of the area where the fiber is present and the area away from it, resulting in the same problem as in the previous example.Especially, when it is desired to increase productivity by making the precursor fiber 101 multi-filamentary,
The above problem is exacerbated because it is necessary to widen the furnace width and the fibers themselves tend to prevent the heat transfer particles from becoming fluidized.

Furthermore, in order to fluidize the fluidized bed 5, the gas sent through the dispersion plate 8 needs to have a pressure and flow rate above a certain level. This pressure needs to be greater as the height of the fluidized bed 5 becomes higher. However, if the pressure becomes too high, the kinetic energy of the heating medium particles becomes too large, and the collision energy of the heating medium particles against the precursor fibers 101 (FIGS. 13 and 14) becomes too high. If the collision energy becomes too high, damage to the fibers may occur. In order to prevent the above fiber damage while achieving fluidization, it is necessary to keep the height of the fluidized bed 5 small and to lower the gas pressure for fluidization. However, in the heating structure shown in FIGS. 13 and 14, in order to uniformly heat the fluidized bed 5 to a predetermined temperature, a heating area of the heating means 70, 71 is required to be larger than a certain level. There is a limit to reducing the height for this purpose, and the gas pressure cannot be lowered sufficiently.

The present invention solves the above-mentioned drawbacks of the prior art, makes it possible to easily widen the width of the fluidized bed, and in particular, when flame-proofing multi-filament precursor fibers, it is possible to achieve a uniform temperature distribution even in a wide width.
The purpose of the present invention is to provide a flame-retardant device capable of heating to a predetermined temperature even if the height of the fluidized bed is low, and by suppressing the height of the fluidized bed, the gas flow velocity can be kept low and damage to the fibers can be prevented. 1゜[Means for Solving the Problem] ``The flame-retardant device of the present invention in accordance with this purpose has a dispersion plate-1-
In a flame-retardant device that continuously heat-treats precursor fibers in a fluidized bed in which heating medium particles deposited on A guide means is provided for arranging the precursor fibers in multiple rows in the vertical direction, and for arranging the height 1-1 of the precursor fibers from the dispersion plate in the range of 5 mm≦H≦500 mm. A heating means for heating the oxidizing gas is installed in the gas path leading to the oxidizing gas.

In the present invention, precursor fibers refer to filaments, strands, and tow-like fibers obtained by spinning organic polymers such as polyacrylonitrile (PA, N), regenerated cellulose, phenol, pitch, etc. It refers to continuous or discontinuous bodies of , and their spun yarns, fabrics, textiles, etc., regardless of their particular form.

Further, in the present invention, carbon fiber is a general term including graphite fiber.

The fluidized bed in the present invention is a means for heat-treating solid heat transfer particles in a state in which they are fluidized with gas, and the heat transfer particles are in a state in which they are fluidized in an oxidizing gas and at a predetermined temperature, preferably 200°C. It refers to a state where it is heated to a temperature of 240'C or higher, preferably 240'C or higher, or a state where it coexists in this fluidized bed.

In the present invention, the oxidizing gas includes, in addition to air, gases that cause an oxidation reaction in a broad sense when heated on the precursor fibers, such as sulfur-containing gas.

The heating medium particles according to the present invention refer to solid particles used in a gaseous fluidized state, and have heat resistance that can withstand 7 Jl heat temperature required for flame resistance, that is, 350'C or more, preferably 40
It is possible to use inorganic particles such as ceramic or glass that have heat resistance of 0°C or lower and are composed of carbon, alumina, silicon carbide, zirconia, silica, etc. as the main components, singly or in combination. .

Furthermore, among the heat transfer particles, particles containing carbon as a main component (carbon particles) are preferable.

The carbon particles are typified by carbon black, thermal black, carbon hollow spheres, activated carbon powder, spherical activated carbon, grassy carbon powder, mesofaced bridge beads, artificial graphite powder, granular graphite, natural graphite powder, etc., and their compositions These are carbon particles having a carbon content of 50% or more, preferably 90% or more. These heat transfer particles made of inorganic substances, carbon, etc., are composed of metal components that react with carbon during the carbonization process, such as Fe, Ca, fVIg, Mr), Cu1/"
The less 1, Or, Ni, etc., the better. In the case of heating medium particles whose main component is carbon, even if they are attached to the heating medium particles or fibers and brought into the carbonization process, the metal components contained in the particles will react with the carbon in the particles. Therefore, the physical properties of the carbon fiber are not essentially deteriorated. Further, since the particles can penetrate into the spaces between the single filaments of the fibers during flameproofing, thereby preventing fusion between the single filaments, there is no particular limitation on the finer particle size.

The particle size is determined by the measurement method according to JIS Z 8801 and JISH 8511-1960 for graphite powder, and the particle size is 80% or more of the weight or the particle size is 10 meshes (Tyler method) or less, preferably 28 meshes or less. good. If the particle size is larger than this, a large amount of gas flow is required for fluidization, and the kinetic energy when the particle collides with the precursor fiber becomes large, causing problems with the physics of feathers, etc. Easy to cause damage. On the other hand, if the particle size is small, the gas flow rate required for fluidization is reduced, and damage to the fibers can also be reduced.

The shape of the heat transfer particles is not particularly limited.
- Particles with a shape close to spherical without edges are preferable because they cause less physical damage to the precursor fibers.

In addition, whether it is the particle size or a certain degree of sensitivity, it is important to note that ('J
Since the amount of Ni is small and removal is easy, the lower limit of the particle size when removal is required is preferably 400 mesh, more preferably 200 mesh.

The dispersion plate in the present invention is made of a porous body or a wire mesh body,
Depending on the particle size of the heating medium particles, a predetermined amount of heating medium particles can be deposited on the dispersion plate.

Oxidizing gas is sent into the fluidized bed through this distribution plate, and the heat medium layer is fluidized by the oxidizing gas dispersed by the distribution plate. The oxidizing gas can be heated to a predetermined temperature by a heating means in the waste path leading to the fluidized bed. There is no problem even if the fluidized bed is fluidized and heated to a predetermined temperature at the same time by heating the oxidizing gas to a predetermined temperature in advance.The oxidizing gas is dispersed by a dispersion plate. The fluidized bed is heated uniformly over the entire area.In addition, the oxidizing gas flows into the fluidized bed from substantially the entire bottom side of the fluidized bed, so it is not occluded in the wide fluidized bed. Even if the area is heated evenly over the entire area, a uniform humidity level can be obtained.

The precursor fibers are continuously passed through a fluidized bed through which an oxidizing gas is passed and which is uniformly heated to a predetermined temperature to provide the desired flameproofing treatment.

In the flame-retardant device constituting this fluidized bed, the guide means for threading and arranging the precursor fibers into the flame-retardant device is arranged such that the height H of the fiber path from the distribution plate is 5 mm≦T1≦50.
It is necessary to set the arrangement V so that it is in the range of 0 rrm. 5
If the height exceeds 00 mm, it will be difficult to prevent heat medium particles from leaking out of the furnace from the inlet/outlet holes, and a large amount of oxidizing gas will be required to fluidize the heat medium layer, which will be higher than this. Pressure is required, which can lead to precursor fiber damage problems as described above.

On the other hand, if the diameter is smaller than 5 mm, the precursor fibers must be completely immersed in the fluidized bed or rotated. Furthermore, since the heat capacity of the fluidized bed as a whole decreases in the height direction, it may be difficult to efficiently remove and cover the heat generated by the reaction. However, it is necessary to keep t1 within the range mentioned above.

In the above configuration, a plurality of precursor fibers are arranged two-dimensionally in a cross-section of the fluidized bed perpendicular to the direction in which they pass by a guiding and arranging means, and made to run in the same direction to make them flame resistant. It is preferable that a rotating body having a groove is used as the arranging means so that rllWl is
It is more preferable to make flame resistance by setting the arrangement interval to l within a certain range. The above-mentioned plurality of precursor fibers refers to a state in which 500 to 50,000 filaments of precursor filaments 1 to 1 of 93 to 5 deniers are bundled to form a plurality of at least 10 fibers.

Here, as a rotating body that rotates the groove to the right, the outer diameter surface = 14
- refers to a roller or rotating kite that has continuous recesses in the circumferential direction, regardless of whether or not it has a driving source.

If the fibers are reciprocated in the fluidized bed using rollers or guides, heat transfer particles may get caught between the contact surfaces of the rollers or guides and the fibers, which is undesirable because the fibers are likely to be damaged by fuzz or the like.

Further, the fiber threads may be flame-resistant treated by running them under tension in the same direction from the inlet to the outlet of the fluidized bed. In this case, it is preferable to move in the same direction within an inclination of approximately ±15° from the horizontal plane.

If the processing tension of the fibers is too low, the fibers tend to open and fuzz is generated due to the movement of the heating medium particles, and the rate at which the heating medium particles adhere to the fibers is high and the removability becomes poor.

On the other hand, if the tension is too high, fuzz and thread breakage are likely to occur, so a denier range of approximately 30 to 2.0009/2 is preferable.

Also, as mentioned in the previous section, whether the width of the fluidized bed can be made wider in the present invention, the relationship between the width W and the height 1-1 of the precursor fiber path from the distribution plate is W/] It is desirable that ≧1. If W/H is too small, -15
= This is because the number of fibers that can pass through the fluidized bed at the same time decreases, resulting in poor processing efficiency.

When a desirable area of such height H1 width W is covered in the diagram,
The result is as shown in FIG.

Next, preferred embodiments of the flameproofing device of the present invention will be described.

FIG. 1 shows a schematic sectional view of a flameproofing device according to one embodiment of the present invention.

In the figure, 1 indicates a flameproofing furnace, and a dispersion plate 8 is provided in the furnace 1. A waste dispersion box 90 is formed below the dispersion plate 8, and heat medium particles are deposited on the dispersion plate 8 to a predetermined range of thread path height or higher as shown in FIG. It is configured. This heat medium layer 5 is fluidized by the oxidizing gas (arrow) sent from the gas distribution box 90 through the distribution plate 8 to form a fluidized bed. The oxidizing gas is introduced into the waste dispersion box 90 through the waste passage 9. A heater 6 is provided in the gas passage 9, and the heater 6 heats the oxidizing gas to a predetermined temperature.

In such an apparatus, the oxidizing gas that has flowed into the waste dispersion box 90 spreads uniformly within the gas dispersion cylinder 8 before passing through the dispersion plate 8 due to the pressure loss of the dispersion plate 8 . Then, the oxidizing gas dispersed by the dispersion plate 8 is sent to the heat ts layer 5, and the heat medium @5 is fluidized. The height of the heat medium layer 5 must be greater than the range shown in FIG. 7 and must be such that the yarn path is not exposed to the gas phase during fluidization. When fluidized, the top thread) 5~ from the neck
It's good that it's 20mm higher. With such a height of the heat medium layer, the oxidizing gas is fluidized by a small repulsive force, and the oxidizing gas enters the fluidized bed from the entire region of the distribution plate 8, that is, from the entire bottom side of the fluidized bed. The layers are heated evenly. Furthermore, it is easy to prevent the heating medium particles from leaking out of the furnace from the introduction or exit hole because the static pressure due to the weight of the heating medium layer is low. Even when multiple threads of precursor fibers 101 are passed through simultaneously, the targeted flame-retardant treatment for each precursor fiber 1101 is reliably achieved.

FIG. 2 shows another embodiment in which a heater 72 as heating means is arranged in the gas distribution box 90. Other configurations are similar to those shown in FIG. With this configuration, the radiant heat from the heater 72 is transmitted to the heat medium via the dispersion plate 8, making it possible to improve thermal efficiency compared to the embodiment described above.

FIG. 3 and FIG. 4 show still another actual IM aspect,
By embedding the heater 73 in the distribution plate 8, the distribution plate 8
itself or configured as a heating means. In this way, it is also possible to efficiently heat the oxidizing gas immediately before it enters the fluidized bed. In this case, if the wiring of the heater 73 connected to the heater power source 74 is completely insulated, there will be no problem with separate installation, or if complete insulation is not easy, the distribution plate 8 may be supported via an insulator 75.

FIGS. 5 and 6 show yet another embodiment, in which the waste distribution box 75 is divided into a plurality of chambers 75a. A branch pipe 76a of a pipe 76 for sending oxidizing gas is connected to each damper 75a, and a damper 77 is provided in each branch pipe 76a. With this configuration, when the oxidizing gas heated by the heater 78 is sent to each chamber 75a, the supply flow rate can be adjusted independently for each chamber 75a, and more fine distribution can be performed. Therefore, it becomes possible to equalize the humidity of the -laminar fluidized bed.

Next, a further preferred embodiment of the flame resistant device of the present invention will be described in the eighth section.
This will be explained in detail using FIGS. 1 to 10.

8 to 10 show a more desirable flame resistant device according to the first embodiment/II aspect of the present invention as an embodiment of the device for flame resistant a 25-thread precursor fiber, and FIG. Its schematic diagram, FIG. 9 is a partial plan view of FIG. 8 excluding the feeding part and winding part, and FIG. 10 is a schematic diagram showing the section 7-7 in FIG. 8.

In FIGS. 8 and 9, 25 packages 30
(Part of the figure is omitted) The precursor fiber yarn 101 fed out passes through the kite roller 37 and then the drive roller 3
A pair of rotary bodies 41 and 42 having grooves as guide and arrangement means are used to arrange the five yarns in a basically vertical direction, and the five sets of rotary bodies are arranged as shown in FIG. The fibers are formed into a two-dimensional array of five parallel rows, and threaded into the fluidized bed 5 of the fluidized bed heating flameproofing furnace 1 for flameproofing treatment. The flame-retardant yarn 102 is led out of the flame-retardant furnace 1, and then, if necessary, the yarn is passed through a removal means 20 for removing the remaining heating medium, and then passed through a removal means 20 for removing the remaining heating medium. A rotary body 43 having an arrangement means configured in the same manner as, that is, a groove portion.
．． 44, the package 31 is wound up via a drive roller 34 and a guide roller 38. The processing tension of the flame-resistant thread 101 is as follows:
are maintained by setting each to a predetermined rotation speed. Of the drive rollers 33 and 34, the rollers 33a and 34a closest to the arrangement means are preferably grooved rollers.

With the above configuration, as shown in FIG. 10, it is possible to thread the precursor fiber threads in a two-dimensional arrangement within the cross section of the fluidized bed 5 perpendicular to the running direction of the threads. Must have. At that time, the arrangement means old, 42, 43, 44, the height ['' from the dispersion plate of the fiber braid threading is 5mm≦H≦500mm.
It is necessary to place it within the range of . In this example, the precursor fiber threads were, for example, 12,000 denier, the pitch between the threads in the vertical direction was 5 mm, and the "HW
Since it is possible to perform flameproofing treatment by setting the inter-row pitch Pl in the direction of 20 to 30 mm, the depth of the ripening medium layer is 30 to 30 mm.
About 40 mm is sufficient. In general, at least rl
It is preferable to set the inter-row pitch P1 in the JW direction to 15 mm or more in order not to impede the fluidity of the heat medium. The upper limit is preferably 100 mm or less, preferably 50 mm or less, since processing density can be increased. Here, the inter-row pitch P1 in the width direction is the center-to-center distance of the widthwise variation r of each row. For example, the arranging means as described in P.
As shown in the figure, it is composed of a free roller having a continuous groove 63 in the circumferential direction.

When such an arrangement means is used, the yarn is flattened in the vertical direction along the groove bottom, so even if the yarn is thick, the thickness can be kept small and heat can be efficiently removed from the outer periphery. Therefore, the amount of heat stored in the fiber bundle due to heat generated by oxidation reaction can be suppressed to a small level. As a result, the processing temperature can be increased and the processing time can be shortened.

In FIG. 8, in the flameproofing furnace 1, a fluidized bed 5 of heat medium particles is formed on the dispersion plate 8'2, and the fluidized beds 5-21- are passed through the dispersion plate 8 through the supply holes 9. It is fluidized by the sent oxidizing gas, and the fluidized gas is passed through the exhaust hole 1.
Ejected from (). In addition, this heat medium fluidized bed 5 has heating means (
Heaters) 6.7 control the heating to predetermined processing temperatures, and the partition plate 12 forms two heating regions 3.4, making it possible to raise the temperature in two stages. of course,
It can be configured with one heating zone or even more heating zones.

If the introduction/exit holes through which the fiber threads are introduced into the fluidized bed 5 of the flameproofing furnace 1 are left open, heat medium and heated air will flow out, so pressurized seal chambers 11 and 11' are provided to prevent the gas from flowing out. is supplied to each from the supply holes 13 and 13-, and the atmospheric pressure in the pressurized sealing chamber is made slightly higher than the atmospheric pressure in the furnace to seal the heating medium and the heated air. Of course, other sealing methods may be used, such as an ejector that generates a gas flow toward the inside of the furnace, or in some cases, the heating medium flowing out to the seal U cover may be automatically transferred to W1'1 and sequentially into the fluidized bed. A system that returns it is also possible.

Flame resistant fiber 102 obtained by the flame resistant method of the present invention
Alternatively, if necessary, 103 can be continuously carbonized using a carbonization furnace 2 as shown in FIG. 12 to form a package 32 of carbon fibers 104, or can be carbonized in batches to form carbon fibers. .

The carbonization furnace 2 is heated using an inert gas such as N2, △r
゛, Can be used in an atmosphere such as He, and has a specified carbonization temperature?
There is no particular limitation, and methods such as resistance heating and induction heating can be used as long as the method is suitable. Note that 35. in FIG.
36 is a drive roller, 50 is an inert gas supply hole, and 51 is an exhaust hole thereof.

In the examples shown in FIGS. 8 to 12, the flame-retardant treatment and the carbonization treatment are performed separately, but after the flame-retardant treatment, the flame-retardant fiber 102 or 103 is further continuously carbonized. The carbon fiber 104 can also be obtained by

[Effects of the Invention] As explained above, when using the flameproofing device of the present invention, the height of the precursor fiber thread path from the distribution plate is set within a predetermined range by the thread arranging means (guiding means), Since the oxidizing gas sent into the fluidized bed through the dispersion plate is heated in the waste path leading to the fluidized bed, it is possible to obtain a uniform temperature distribution even if the width of the fluidized bed is widened. It is necessary to reliably prevent damage to the flame-retardant fibers by suppressing the repulsion of the gas necessary for oxidation, and also to easily prevent leakage of the heat medium from the introduction orifice of the fibers into the heat medium layer. Therefore, production efficiency can be improved and carbon fibers with excellent physical properties can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a flame resistant device according to one embodiment of the present invention, FIG. 2 is a schematic sectional view of a flame resistant device according to another embodiment, and FIG. 3 is a flame resistant device according to yet another embodiment. Fig. 4 is a schematic cross-sectional view of a flame retardant device with the dispersion plate of Fig. 3 attached, =24- Fig. 5 is a schematic plan view of a dispersion plate used in a flame retardant device according to a completely different embodiment. 6 is a schematic plan view of the gas distribution box of the device shown in FIG. 5; FIG. 7 is a graph showing the desirable ranges of the height H of the yarn path and the width W of the heating medium layer; 9 is a partial plan view of the schematic diagram shown in FIG. 8, and FIG. 11 is a schematic sectional view showing an example of a precursor fiber arrangement means; FIG. 12 is a schematic sectional view showing an example of a method for carbonizing the obtained flame-resistant fibers. , FIG. 13 is a schematic sectional view of a conventional flame resistant device, and FIG. 14 is a schematic sectional view of another conventional flame resistant device. 1: Flameproofing furnace 2: Carbonization furnace 3: First stage heating zone 4: Second stage heating zone 5: Heat medium particle layer 6.7: Heater 8.8-: Dispersion plate 9.9-: Air supply hole 10: Exhaust hole, 11-: Calibration seal chamber 12: Partition plate 13.13-: Air supply hole 20: Heat medium removal means 30: Precursor fiber package 31: Flame-resistant fiber package 32: Carbon fiber package 33 .34.35.36: Drive rollers 33a, 34a: Grooved rollers 37.38.39.4(): Kite rollers 41.42.
43.44: Rotating body with groove 50: Inert gas supply hole 51: Inert gas exhaust hole 61: Free roller 62: Shaft 63: Groove 64: Bearing 101: Precursor fiber thread 102.103: Flame resistant 111i fiber 104: carbon fiber

Claims (1)

[Claims] 1. The precursor fibers are continuously heat-treated in a fluidized bed in which the heating medium particles deposited on the dispersion plate are fluidized by the oxidizing gas dispersed by the dispersion plate. In the flameproofing device, the precursor fibers are arranged in multiple rows in the vertical direction, and a guide means is provided for arranging the precursor fibers at a height H from the dispersion plate in the range of 5 mm≦H≦500 mm. A flame-retardant device, characterized in that a heating means for heating the oxidizing gas is provided in the gas path leading the oxidizing gas to the fluidized bed.