JPH06173123A - Method for sealing infusibilizing furnace for pitch-based carbon fiber and apparatus therefor - Google Patents

Abstract

PURPOSE:To provide a method for sealing an infusibilizing furnace in which the reaction is prevented from nonuniformizing and fiber flaw is prevented from occurring by a contact method with the fiber. CONSTITUTION:This method for sealing an infusibilizing furnace for pitch-based carbon fiber is to respectively install sealing chambers 4 and 5 in openings 2 and 3 of the infusibilizing furnace 1 for the pitch-based carbon fiber, provide a gas discharge port 6 in at least one place of the respective sealing chambers, carry out the gas suction by a gas discharge device 8, lead a gas in the furnace to the inlet and outlet sealing chambers, simultaneously suck the air from one end of the sealing chamber, form a flow in the direction opposite the direction of the gas in the furnace and thereby prevent the gas in the infusibilizing furnace from leaking into the air. As a result, a product excellent in quality without any yarn flaw can stably be produced and an infusibilization reactional accelerator can safely be utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infusible furnace sealing method and apparatus for heat treating a precursor fiber obtained by melt-spinning a pitch-based carbon fiber-forming substance. In particular, the present invention relates to a gas sealing method for an inlet and an outlet of an infusible furnace and an apparatus for the same, in which precursor fibers are continuously or intermittently introduced into an infusible furnace whose atmosphere is adjusted, treated, and then discharged.

[0002]

2. Description of the Related Art When a precursor fiber obtained by melt-spinning a pitch-based carbon fiber-forming substance is heated to a high temperature (carbonization) in a non-oxidizing atmosphere, most of the atoms other than carbon are removed, and Become a fiber. However, if the precursor fiber is rapidly heated to a high temperature, the fiber will melt. Therefore, before carbonization, a precursor fiber obtained by melt spinning is loaded on a net conveyor that moves in the infusible furnace, and the net conveyor travels from the infusible furnace inlet to the outlet. However, a method of performing heat treatment at a relatively low temperature in an oxidizing atmosphere is used. In such an infusibilizing furnace, it is known that when the precursor fiber is heat-treated at about 200 ° C., the fiber itself generates heat by an exothermic reaction. In the infusibilizing treatment of the precursor fiber, the precursor fiber is heated under an appropriate temperature condition. You have to control it gradually. Therefore, in the carbon fiber manufacturing process, the time required for the infusibilization treatment is significantly longer than the time required for the carbonization process in the subsequent process, and the process is an obstacle to improving the productivity. It was

However, if the infusibilizing treatment temperature is raised, the reaction rate is increased and the treatment time is shortened.
If the infusibilization temperature is too high, the exothermic reaction becomes faster than the heat removal rate, the temperature inside the fiber rises, the heat generation rate becomes even faster, and the temperature inside the fiber becomes faster than the infusibilization temperature. It rises and eventually the fibers burn.

As a method for solving such a problem, an infusibilizing reaction accelerator (for example, NO ₂ , Cl ₂ or SO ₂ etc.) is added to the infusibilizing furnace to increase the reaction rate, thereby shortening the infusibilizing time. Method is used. However, a strong oxidizer such as NO ₂ , Cl ₂ or SO ₂ is used as the infusible reaction accelerator, and any of them corresponds to a dangerous substance. Therefore, gas leakage to the outside of the infusible furnace is preferable. However, there is a considerable difference in gas concentration and pressure between the inside and outside of the furnace, so some of the gas in the furnace leaks out of the infusible furnace through the gap between the net conveyor and the fiber layer. In view of safety and hygiene, there has been a strong demand for a method and a device for completely sealing the inside and outside of the infusible furnace as a measure for preventing gas leakage to the outside of the infusible furnace.

As a method for sealing a pitch-based carbon fiber infusible furnace for solving the above-mentioned problems, Japanese Patent Laid-Open No. 167928/1985 has been proposed.
No. 5, the precursor fiber obtained by melt spinning on a net conveyor moving in the furnace, the infusible furnace inlet and outlet openings are provided with a net conveyor and sealing rolls above and below the fiber layer, and pressure bonded. However, a method of sealing the inside and outside of the furnace (nip roll method) is disclosed.

However, according to the above method, the convex and concave portions of the pitch-based carbon fiber loading surface are pressure-bonded to increase the bulk density, the flow velocity of the gas passing through the fiber layer is decreased, the reaction becomes non-uniform, and a homogeneous product is obtained. Is difficult to obtain. In particular, when the irregularities are severe, it becomes difficult for the gas to flow, and the heat of oxidation of the fibers of the pressure-bonded portion is accumulated, which may cause a runaway reaction and may lead to combustion.
Also, if the unevenness of loading is large, it is often impossible to completely eliminate the ventilation part with the outside of the furnace due to the effects of conveyor accessories, etc., it is not possible to completely prevent the leakage of gas in the furnace, and further, the pitch fiber Such a fragile fiber is easily scratched when sandwiched by rolls, causing problems such as fluffing, deterioration such as single yarn breakage, and electrostatic charge.

[0007] Similarly, as another method for sealing a pitch-based carbon fiber infusible furnace for solving the above-mentioned problems, there is disclosed in Japanese Patent Laid-Open No.
No. 5-90621 is loaded with precursor fibers obtained by melt spinning on a net conveyor moving in a furnace, and a net conveyor and sealing rolls are provided above and below the fiber layer at the infusible furnace inlet and outlet openings. There is disclosed a sealing method in which the inside and the outside of the furnace are sealed while crimping (nip roll system), and a gas seal (air curtain system) is formed by flowing air or nitrogen inside the furnace at the inlet and the outlet of the furnace. ing. According to this method, compared with a case where a sealing roll is provided and the inside and outside of the furnace are sealed while being pressure bonded (nip roll method), the fiber layers loaded on the net conveyor inside the furnace at the entrance and exit of the furnace By carrying out gas sealing by passing air or nitrogen from the direction perpendicular to the loading surface, most of the gas containing the infusibilizing reaction accelerator can be recovered from the gas outlet in the furnace.

However, the gas is circulated in the furnace so that the gas containing the infusible reaction accelerator uniformly contacts the fiber layer, and the gas seal provides a sealing property in the vicinity of the gas outlet and the suction port. However, in the middle thereof, the gas sealing property is deteriorated when coming into contact with the circulating gas and passing through the loaded fiber layer, and it is impossible to completely seal 100%. Further, as a problem caused by the contact method by the nip roll method as described above, the convex portion of the unevenness of the pitch fiber loading surface is pressure-bonded to increase the bulk density, the flow velocity of the gas passing through the fiber layer is decreased, and the reaction is unsatisfactory. It becomes uniform and it is difficult to obtain a homogeneous product. In particular, when the irregularities are severe, it becomes difficult for the gas to flow, and the heat of oxidation of the fibers of the pressure-bonded portion is accumulated, which may cause a runaway reaction and may lead to combustion. further,
Fragile fibers such as pitch fibers are easily scratched when sandwiched by rolls, and have problems such as fluffing, deterioration such as single yarn breakage, and static electricity.

[0009]

Therefore, an object of the present invention is to provide a method for sealing a pitch-based carbon fiber infusible furnace as a sealing method.
(EN) A method and a device for completely sealing the inside of a furnace by a non-contact sealing method capable of preventing nonuniform reaction due to a method of contacting fibers and generation of fiber flaws.

[0010]

DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly studied a method and apparatus for sealing a pitch-based carbon fiber infusible furnace, and as a result, have been connected to the inlet and outlet of the pitch-based carbon fiber infusible furnace. A non-contact sealing can be performed by providing a gas-intake chamber by providing an exhaust port in the chamber so that the gas pressure in the infusible furnace becomes lower than the atmospheric pressure and the infusible furnace gas inside the chamber, By forming the air flow in the opposite direction and utilizing the air flow as a countercurrent to the in-furnace gas flow, the infusible in-furnace gas is all sucked from the exhaust port without leaking from the chamber to the outside. By
Knowing that the above object can be achieved, the present invention has been completed based on this finding.

Further, in the present invention, in the case of providing a chamber having an exhaust port at the inlet and the outlet of the infusibilizing furnace, the present inventors set the position of the exhaust port, the set amount of gas exhausted from the exhaust port, etc. Depending on the case, on the inlet side of the infusible furnace, the pitch-based carbon fiber is rapidly heated by the high-temperature oxidizing gas sent from the inside of the infusible furnace to easily cause a runaway reaction, and on the outlet side of the infusible furnace. , The infusibilized fiber is easily re-oxidized by being continuously exposed to the high temperature oxidizing gas delivered from the infusible furnace and the high temperature oxidizing gas entrained in the fiber. Since there is a possibility that the fiber may deteriorate due to the abnormal temperature rise, the inventors of the present invention further investigated the abnormal temperature rise measures, and as a result, provided an inert gas supply port in the chamber, Inert gas supply port The inert gas is blown to the fiber Ri,
It has also been found that the abnormal temperature rise can be extremely effectively prevented by purging the fiber-containing oxidizing gas.

That is, the object of the present invention is to provide a seal chamber at each of the inlet and the outlet of the pitch-based carbon fiber infusible furnace, and to provide an exhaust port at at least one location of each seal chamber so that a gas generated by an exhaust device is used. Suction is conducted, the gas in the furnace is introduced into the inlet and outlet seal chambers, and at the same time, the atmosphere is sucked from one end of the seal chamber to form a flow in the direction opposite to the flow direction of the gas in the furnace, This can be achieved by a sealing method (1) for a pitch-based carbon fiber infusible furnace, which is characterized in that gas is prevented from leaking to the atmosphere.

Still another object of the present invention is to provide at least one inert gas supply port in the seal chamber at the inlet and / or the outlet of the infusible furnace, and blow the inert gas through the inert gas supply port to the fiber layer. This can be achieved by the method (2) of sealing the pitch-based carbon fiber infusible furnace described in (1) above, in which the oxidizing gas accompanying the fiber layer is purged.

Another object of the present invention is to provide seal chambers connected to the inlet and outlet openings of a pitch-based carbon fiber infusible furnace, respectively, and exhaust gas provided at least at one position of each seal chamber. It can be achieved by a sealing device (3) for a pitch-based carbon fiber infusible furnace, characterized in that it comprises a gas suction exhaust means connected to the mouth.

Another object of the present invention is to provide the pitch-based carbon fiber according to the above (3), wherein at least one inert gas supply port is provided in the seal chamber at the inlet and / or the outlet of the infusibilizing furnace. This can be achieved by the infusible furnace sealing device (4). .

Still another object of the present invention is to provide at least one resistor in the seal chamber in the longitudinal direction of the seal chamber so as to secure a space of a fiber layer which is orthogonal to the gas flow and moves in the seal chamber. It can be achieved by the provided seal device (5) for the pitch-based carbon fiber infusible furnace according to (3) or (4).

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic side sectional view showing an embodiment of an infusible furnace sealing apparatus for carrying out the pitch-based carbon fiber infusible furnace sealing method according to the present invention.

As shown in FIG. 1, in the infusible furnace sealing apparatus of the present invention, the pitch carbon fibers are connected to the inlet opening 2 and the outlet opening 3 of the infusible furnace 1 in such a manner that they are completely sealed from the outside air. An inlet side seal chamber 4 and an outlet side seal chamber 5 are provided, and an exhaust device 8 connected to an exhaust port 6 provided at at least one location of each of the seal chambers 4 and 5 by a connecting pipe 7 is provided. Further, the inlet side seal chamber 4, the infusibilizing furnace 1 and the outlet side seal chamber 5 are connected in this order and a transfer device 9 such as a net conveyor is stretched.

Further, preferably, inside the inlet-side seal chamber 4 and the outlet-side seal chamber 5, there is a space for the fiber layer 10 which is perpendicular to the longitudinal direction of the seal chamber and is substantially orthogonal to the gas flow and moves in the seal chamber. At least one resistor 11a, 11b is provided before and after the exhaust port so as to be secured. Of these resistors, the lower resistor 11b is provided so that its upper end does not come into contact with the transport device 9 and almost reaches the lower part of the transport device, and the upper resistor 11a.
Although it may be a fixed type, it is preferably provided so as to be movable up and down according to the thickness of the fiber layer 10, and it is preferable to operate by lowering it so as not to contact the fiber layer 10.

Further, the inlet side seal chamber 4 of the infusible furnace 1
The outlet side seal chamber 5 and the outlet side seal chamber 5 are provided with at least one inlet side inert gas supply port 13a and at least one outlet side inert gas supply port 13b respectively on the wall surfaces of the both seal chambers, and the exhaust gas is preferably respectively provided. It is desirable that the port 6 and each of the inert gas supply ports 13 are located on the chamber wall surfaces facing each other with respect to the transfer device 9.

Each of these inert gas supply ports 13a, 13
More preferably, b and the exhaust port 6 are provided with an inert gas supply port 13 on the bottom surface of each of the seal chambers 4 and 5 so that the fiber layer 10 loaded on the traveling transport device 9 is less affected.
a and 13b are provided, and the exhaust ports 6 are provided on the upper surfaces of the walls of the seal chambers 4 and 5 at the opposite positions so that the gas flow penetrates the fiber layer 10 from bottom to top in a piston flow manner. ing. That is, if the gas flow makes a vortex with respect to the fiber layer 10, the fibers are entangled with each other and the fiber layer 10 collapses, which is not preferable, and the gas flow from the top to the bottom at the inlet of the infusible furnace 1 is a piston flow. If it is penetrated, the fiber layer 10 is crushed, the bulk density is increased, it is difficult for gas to pass into the inside of the fiber in the infusible furnace, the internal temperature is increased, and a runaway reaction is likely to occur, which is not preferable.

Furthermore, each of these inert gas supply ports 13
It is more preferable that both a and 13b are provided at positions close to the infusibilizing furnace 1. That is, on the inlet side of the infusible furnace 1, it is effective to prevent the fiber layer 10 from being rapidly heated and causing a runaway reaction by the high temperature oxidizing gas delivered from the inside of the infusible furnace 1. On the outlet side of the infusibilizing furnace 1, the infusibilizing layer 1 is infusibilized by being continuously exposed to the high temperature oxidizing gas delivered from the infusibilizing furnace 1 and the oxidizing gas entrained in the fiber layer 10. It is effective in preventing 10 from being reoxidized. In particular, the outlet side inert gas supply port 13 provided in the outlet side seal chamber 5 of the infusible furnace 1
As for b, it is more preferable to provide the inert gas supply ports 13b in a plurality of stages in the fiber advancing direction. As a result, the inert gas is blown through the fibrous layer 10 one after another in a piston flow manner between the exhaust port 6 provided at a position opposed to the inert gas supply port 13b, so that the fiber layer 10 is swift and sufficient. The oxidizing gas accompanying the fiber layer can be purged and discharged to the outside of the system through the exhaust port 6, whereby the ability to remove the oxidizing gas can be improved without being reoxidized.

In the sealing device 1 having such a structure,
Precursor fibers obtained by melt-spinning a pitch-based carbon fiber-forming substance are loaded in a state of a fiber layer 10 on a conveying device 9 so as to form a layer having an appropriate thickness, and continuously fed from an inlet-side seal chamber inlet 4a. Is supplied to.

In this case, first, in the inlet side seal chamber 4, there is always an opening between the outside and the infusibilizing furnace 1 through the space of the fiber layer 10 moving in the seal chamber 4, so that the inlet side seal chamber 4 is always present. 4 is made infusible by adjusting the amount of exhaust gas by the exhaust device 8 so that the pressure at the exhaust port 6 provided at 4 becomes lower than the inert gas supply pressure and the atmospheric pressure in the infusible furnace. While introducing an oxidizing gas containing an infusible reaction accelerator from the furnace 1, the inlet side seal chamber 4
By sucking the atmosphere from the inlet of the, the flow of the oxidizing gas in the opposite direction to the flow direction is formed by the atmosphere,
An inert gas is introduced from the inert gas supply port 13a, and a gas seal layer of the inert gas is formed toward the opposing exhaust port 6.

Further, the oxidizing gas introduced by the pressure difference between the inside of the infusible furnace 1 cannot proceed against the gas seal layer and further against the flow of the atmosphere, and the atmosphere from the inlet side seal chamber 4 is not allowed. Can not be leaked inside. This allows
It is possible to prevent the oxidizing gas containing the infusibilizing reaction accelerator (NO ₂ , Cl ₂ , SO _2, etc.) from leaking to the outside air, and ensure safety in terms of environmental hygiene. Further, by providing the inert gas supply port 13a and the exhaust port 6 close to the infusible furnace 1, the oxidizing gas introduced from the infusible furnace 1 can be immediately replaced and sucked and discharged to the outside of the system. The runaway reaction of the fiber layer 10 due to the oxidizing gas can be prevented.

The fiber layer 10 supplied into the infusible furnace 1
Contains the atmosphere from the inlet of the inlet-side seal chamber 4 to the exhaust port 6, but when the gas seal layer portion by the inert gas and the exhaust port 6 are passed through, the infusible furnace 1 has a pressure difference.
When it is replaced with an oxidizing gas containing an infusible reaction accelerator and is supplied into the infusible furnace 1, the atmosphere is close to the atmosphere in the furnace. It is possible to prevent temperature disturbance.

Subsequently, the fiber layer 10 is conveyed from the inlet side seal chamber 4 to the infusible furnace 1.

In the infusible furnace 1, the infusible furnace gas supply pipe 1
2 is supplied with oxygen and / or air having a predetermined composition containing an infusible reaction accelerator such as NO ₂ , Cl ₂ , SO _{2 and the} like, and the fiber layer 10 is heat-treated at a predetermined temperature in an oxidizing atmosphere. Infusibilized. Heating is usually performed by a heater provided in the furnace.

Subsequently, the preferably infusibilized fiber layer 10
Is carried out from the infusibilizing furnace to the outlet side seal chamber 5.

In the outlet-side seal chamber 5, the seal chamber 5
An inert gas is introduced from the outlet-side inert gas supply ports 13b provided in a plurality of stages (two stages) to the fiber layer 10 so that the gas flow penetrates the fiber layer 10 from the bottom to the top in a piston flow manner. From the exhaust port 6 facing the gas supply port 13b, the exhaust amount is adjusted by the exhaust device 8 so as to be lower than the internal pressure of the infusible furnace 1, the inert gas supply pressure, and the atmospheric pressure, and the gas is sucked. Thus, the high temperature oxidizing gas entrained in the fiber layer 10 and the high temperature oxidizing gas derived by the pressure difference between the inside of the infusible furnace 1 are guided to the outlet side sealing chamber 5, while the outlet side sealing chamber outlet By suctioning the atmosphere from 5a, a flow in the direction opposite to the flow direction of the oxidizing gas is formed by the atmosphere, and at the same time, the inert gas is supplied from the inert gas supply port 13b so that it is directed toward the opposing exhaust port 6. Gas atmosphere with active gas To form a layer.

As a result, the fiber layer 10 carried out from the infusibilizing furnace 1 contains a high-temperature oxidizing gas containing an infusibilizing reaction accelerator from the infusibilizing furnace outlet opening 3 to the exhaust port 6. It is replaced with an inert gas when passing through the gas sealing layer and further through the exhaust port 6, and contains an inert gas (and part of the atmosphere) when continuously taken out from the outlet side seal chamber outlet 5a. Only. Therefore, the oxidizing gas cannot pass through the exhaust port 6 and proceed against the flow of the gas seal layer and the atmosphere, and is exhausted from the exhaust port 6 to the atmosphere from the outlet side seal chamber outlet 5a. The infusible reaction accelerator (NO ₂ , C
It is possible to prevent leakage of an oxidizing gas containing 1 ₂ , SO _2, etc.) to the outside air, and ensure safety in terms of environmental hygiene.

Further, by providing the inert gas supply port 13b and the exhaust port 6 close to the infusible furnace 1, the high temperature oxidizing gas entrained in the fiber layer 10 and the infusible gas introduced from the infusible furnace 1 are introduced. Immediately replaces and sucks high-temperature oxidizing gas containing a liquefaction reaction accelerator, and is completely introduced.High-temperature oxidizing gas containing infusible reaction accelerator is immediately replaced and sucked out completely to completely remove the oxidizing gas. It can be discharged to the outside of the system via 6. As a result, oxidation of the fiber layer 10 due to oxidizing gas in the outlet side seal chamber 5 is prevented, yield loss due to peroxidation is prevented, and runaway caused by exposure to high temperature oxidizing gas for a long time. It is possible to prevent combustion due to the reaction.

Further, as the pressure level of the exhaust port in the seal chamber is lowered, the sealing property is improved as described above, but on the contrary, the suction amount of the infusible furnace gas and the atmosphere is increased, and the furnace gas cost and the exhaust gas are exhausted. Not only is it uneconomical because of the large size of the device, but also because the sucked gas contains dangerous substances, it cannot be discharged into the atmosphere as it is, and it is necessary to purify it by using some kind of exhaust gas treatment device. Therefore, it is preferable to reduce the gas treatment amount as much as possible. Therefore, by providing the resistor 12 inside the seal chamber, which is orthogonal to the gas flow in the longitudinal direction of the seal chamber and can secure the space of the fiber layer 10 that moves in the seal chamber, the resistor 12 can prevent the gas in the furnace from flowing. Since it works as a resistance against the flow of air in the seal chamber, the pressure of the exhaust port 6 can be kept low even with a small suction amount.
Further, the resistor 12 is a fiber layer 10 that moves in the seal chamber.
The height of the resistor is changed according to the height of the fiber layer within a range not in contact with the upper surface of the fiber layer so that the fiber layer space can be secured in a non-contact state without affecting the space of the exhaust port 6
Is appropriately determined so as to reduce the pressure fluctuation.

[0035]

EXAMPLES Next, examples of the present invention will be described.

Example 1 As the sealing device for the infusible furnace of the present invention shown in FIG. 1, the inlet opening 2 and the outlet opening 3 of the pitch-based carbon fiber infusible furnace 1 were completely sealed from the outside air. An inlet-side seal chamber 4 and an outlet-side seal chamber 5 that are connected in a shape, and an exhaust device 8 that is connected to an exhaust port 6 provided at each one of the two seal chambers via a connecting pipe 7. A net conveyor 9 that connects the inlet-side seal chamber 4, the infusibilizing furnace 1 and the outlet-side seal chamber 5 in this order is stretched, and a gas is introduced inside the inlet-side seal chamber 4 and the outlet-side seal chamber 5 in the longitudinal direction of the seal chamber. Connect the resistor 11 to the exhaust port 6 so that it is orthogonal to the flow.
3 each before and after, and 7 in each longitudinal direction of each sealing chamber.
The one provided so as to be divided into equal parts was used.

In the above apparatus, the fiber layer 10 stacked so as to form a layer having a packing density of 0.03 g / cm ³ and a layer height of 10 to 20 cm on the net conveyor as the conveying device 9 is provided on the inlet side. It is continuously supplied from the seal chamber inlet 4a at a conveyor speed of 2.5 m / h, and the infusible furnace 1 is replenished with the in-furnace gas containing the infusible reaction accelerator (NO ₂ ) to about 1
In an experiment in which heat treatment was performed at 00 to 300 ° C., the mixture was conveyed from the furnace outlet opening 3 to the outlet side seal chamber 5 and taken out from the seal chamber outlet 5a, the pressures of the exhaust ports provided in both seal chambers were infusible at the same time. The exhaust amount is adjusted to 300 m ³ / h by an exhaust device so that the pressure is lower than the internal pressure and atmospheric pressure, and gas suction is performed, and both furnace gas containing the infusible reaction accelerator is sealed from the opening of the infusible furnace. The air was introduced into the chamber and, at the same time, air was sucked from the inlets or outlets of both seal chambers to form a flow in the direction opposite to the flow direction of the gas in the furnace by the air.

At this time, the concentration of the infusibilizing reaction accelerator (NO ₂ ) contained in the internal gas of both seal chambers was measured by sampling each of the compartments divided into seven equal parts by the resistor in the longitudinal direction of the seal chambers. did. The results obtained are shown in Table 1.

[0039]

[Table 1]

From the results shown in Table 1, the infusible reaction accelerator (NO
It was confirmed that the in-furnace gas containing ₂ ) did not exist in the compartments on the inlet 4a side of the inlet side seal chamber and the outlet 5a side of the outlet side seal chamber that passed through the exhaust port.

Embodiment 2 In Embodiment 1, an inert gas supply port 13a is provided at one position on the bottom wall surface of the partition area closest to the infusible furnace, which is partitioned by the inlet-side seal chamber 4, and the opposing position is provided. Exhaust port 6
And an inert gas supply port 1 in each of the two compartments adjacent to the infusible furnace, which are partitioned by the outlet-side seal chamber 5.
3b is provided, and the exhaust port 6 is provided at the opposite position,
The same device as in Example 1 was used.

In the above apparatus, the inert gas supply port 13
Nitrogen gas is supplied at a rate of 10 m ³ / h from a, and at the same time, the pressure of the exhaust port 6 provided at a position facing the inert gas supply port 13a is the internal pressure of the infusible furnace 1, the inert gas supply pressure, and the atmospheric pressure. The exhaust amount is adjusted to 150 m ³ / h by the exhaust device 8 so as to be lower than the above, and the inlet side seal chamber 4 is conveyed while performing gas suction, and then 25 m ³ from the outlet side inert gas supply port 13b. / H supply nitrogen gas,
At the same time, the exhaust device is arranged so that the pressure of the exhaust port 6 provided at a position facing each inert gas supply port 13b of the seal chamber 5 becomes lower than the internal pressure of the infusible furnace 1, the inert gas supply pressure and the atmospheric pressure. The same operation as in Example 1 was carried out except that the exhaust amount was adjusted to 150 m ³ / h by 8 and gas suction was performed.

In Example 2, no abnormal temperature rise was observed due to the supply of the inert gas, the runaway reaction of the fiber layer due to the high temperature oxidizing gas could be prevented in the inlet side seal chamber, and the outlet side seal chamber 5 However, it was confirmed that the yield loss due to the peroxidation of the fiber layer due to the oxidizing gas can be prevented, and the combustion due to the runaway reaction can be prevented.

[0044]

EFFECTS OF THE INVENTION Since the pitch-based carbon fiber infusible furnace sealing method and apparatus used in the present invention is a non-contact sealing system, pressure is not directly applied to the fiber layer by a roller or the like, and the fiber layer is not clogged. Since the reaction is carried out uniformly, the runaway reaction can be avoided, and it is possible to stably produce a product of excellent quality without causing any damage to the fiber.

Since the gas in the infusibilizing furnace can be completely prevented from leaking to the atmosphere, the infusibilizing reaction accelerator can be used safely, and thereby the infusibilizing time can be shortened and the productivity can be improved.

Further, by disposing resistors respectively between the infusible furnace inlet and outlet and the exhaust port, there is no disturbance to the atmosphere components and temperature in the furnace, and the exhaust amount can be suppressed to a small amount. .

In addition, the oxidation reaction in the seal chamber can be stopped immediately near the inlet and outlet of the infusible furnace by supplying the inert gas and effectively utilizing it for purging the oxidizing gas, so that the process yield can be prevented from lowering. Since a runaway reaction can be prevented from occurring, stable production can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic view showing one embodiment of a sealing device for a pitch-based carbon fiber infusible furnace according to the present invention, which carries out a sealing method for the infusible furnace.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pitch-based carbon fiber infusibilizing furnace 2 ... Infusibilizing furnace inlet opening 3 ... Infusibilizing furnace outlet opening 4 ... Inlet side seal chamber 4a ... Inlet side seal chamber inlet 5 ... Outlet side seal chamber 5a ... Outlet side seal Chamber outlet 6 ... Exhaust port 7 ... Connection pipe 8 ... Exhaust device 9 ... Conveying device 10 ... Fiber layer 11 ... Resistor 12 ... Infusible furnace gas supply pipe 13 ... Inert gas supply port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Yoshida 20-1 Shintomi, Futtsu City, Chiba Shin Nippon Steel Co., Ltd.

Claims (5)

[Claims] 1. A seal chamber is provided at each of an inlet and an outlet of a pitch-based carbon fiber infusible furnace, and an exhaust port is provided at at least one location of each seal chamber, and gas is sucked by an exhaust device. The gas is guided to the inlet and outlet seal chambers, and at the same time, the atmosphere is sucked from one end of the seal chamber to form a flow in the direction opposite to the flow direction of the gas in the furnace, so that the gas in the infusible furnace does not leak to the atmosphere. A method for sealing a pitch-based carbon fiber infusible furnace, comprising: 2. At least one inert gas supply port is provided in a seal chamber at an inlet and / or an outlet of the infusible furnace, and an inert gas is blown to the fiber layer from the inert gas supply port to obtain the fiber. The method for sealing a pitch-based carbon fiber infusible furnace according to claim 1, wherein the layer-containing oxidizing gas is purged. 3. A gas which is connected to a seal chamber which is connected to an inlet and an outlet of a pitch-based carbon fiber infusible furnace and an exhaust port which is provided at least at one position of each seal chamber. A sealing device for a pitch-based carbon fiber infusible furnace, comprising a suction exhaust means. 4. The sealing device for a pitch-based carbon fiber infusible furnace according to claim 3, wherein at least one inert gas supply port is provided in an inlet and / or an outlet of the infusible furnace. 5. The seal chamber is provided with at least one resistor in the longitudinal direction of the seal chamber, which is orthogonal to the gas flow and which secures a space for a fiber layer that moves in the seal chamber. 3. A sealing device for a pitch-based carbon fiber infusible furnace according to 3 or 4.