JPS6311448B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a carbon fiber manufacturing apparatus for continuously manufacturing carbon fibers with high production efficiency.

[Prior Art] Normally, in order to produce carbon fibers, organic polymers such as polyacrylonitrile fibers, regenerated cellulose fibers, phenolic fibers, and pitch fibers are first heated to 200 to It is produced by making it flameproof at 300°C and then carbonizing it at 800-2000°C in an inert gas atmosphere such as nitrogen or argon. Furthermore, graphitization is performed at 1500 to 3000℃,
Carbon fibers with even higher Young's moduli are also produced.

However, the yarn treatment temperature in the above carbonization and graphitization steps is extremely high, especially at a treatment temperature of 1500
In the high-temperature heating equipment used in the graphitization process, which requires a temperature of ~3000°C, carbon or A cylindrical graphite material is often used, and a thread is passed through the cylindrical material to undergo high-temperature treatment. in this case,
It is well known that the above-mentioned heating elements made of carbon or graphite materials undergo a significant oxidation reaction in an oxidizing atmosphere at high temperatures, and wear out and deteriorate in an extremely short period of time, making them unusable. As a countermeasure, an inert gas such as nitrogen or argon is introduced into the high-temperature heating device to maintain an internal pressure slightly higher than atmospheric pressure, thereby controlling the atmosphere on the inner and outer surfaces of the heating element.

On the other hand, in order to make the heating element made of carbon or graphite exhibit its characteristics efficiently and safely at high temperatures, carbon or graphite particles or The structure is such that it is filled with powder and functions as an intermediate support material and a heat insulating material for the high-temperature heating element. Further, as the heating means of the above-mentioned high-temperature heating device, a Joule heating effect using the electric current of the heating element itself is generally used, such as a Tammann type or a high frequency induction type.

Next, the above-mentioned conventional device will be explained in more detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an example of a Tanmann type furnace conventionally commonly used in a carbonization or graphitization process to produce the above-mentioned carbon fibers. To explain the apparatus shown in FIG. 1 in particular as a graphitization furnace, a carbonized system 1 is continuously introduced into a graphitization furnace 10 from one end by a nip roller 2,
After being graphitized in the graphitization furnace 10, it can be continuously drawn out from the other end by a nip roller 3 as a graphitized fiber 1'. In the main furnace 10, a graphite heating element 4 configured in a cylindrical shape
is thermally supported by graphite powder 5 filled in the furnace as an intermediate support and heat insulating material, and the graphite heating element 4 generates heat by connecting a low-voltage, high-current power source to the water-cooled electrode 6 and directly energizing it. It is now possible to obtain high temperatures of 2500°C to 3000°C. The inside of the graphitization furnace 10 is replaced with nitrogen gas in advance, and even during operation, nitrogen gas is continuously supplied into the graphite heating element 4 from the nitrogen gas inlet 7 provided in the graphitization furnace 10. It has a structure in which the water is ventilated and flows out from the outflow port 8.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional high-temperature heating device, despite the various devices described above, the temperature of the heating element itself made of carbon or graphite is 1500 to 3000°C.
Because of this extremely high temperature, a reaction with the residual oxygen in the heating device or evaporation of carbonaceous material may occur, resulting in wear and tear in an extremely short period of time, making it necessary to frequently replace the heating element. Further, the above-mentioned evaporation phenomenon is thought to rapidly become more intense when the ambient temperature exceeds 2000°C, and the wear on the outer circumferential surface of the heating element is particularly significant. SUMMARY OF THE INVENTION However, it is an object of the present invention to provide a high temperature heating device which makes it possible to largely overcome the above-mentioned problems of the prior art.

[Means for Solving the Problems] The present invention includes a cylindrical heating element made of graphite or carbon, electrodes provided at both ends of the heating element, a heat insulating material provided around the outer periphery of the heating element, A carbon fiber manufacturing apparatus comprising an inert gas inlet provided on one side of the heating element and communicating with the inside of the cylinder, and an inert gas outlet provided on the other side of the heating element and communicating with the inside of the cylinder, between the heat insulating material and the heating element,
A pipe having an inner diameter larger than the outer diameter of the heating element and made of graphite or carbon is provided at a position where the pipe is a sheath and the heating element is the core, and is formed between the pipe and the heating element. Production of carbon fiber characterized in that both sides of the gap are open, one side of the opening communicates with the inert gas inlet, and the other side of the opening communicates with the inert gas outlet. The gist is the device.

Next, the apparatus of the present invention will be explained with reference to the drawings.

FIG. 3 shows the conventional graphitization furnace 10 shown in FIG.
FIG. 4 shows a schematic cross-sectional view of a graphitizing furnace 20 modified according to the present invention, and FIG. 4 shows a schematic vertical cross-sectional view of the central part of the graphitizing furnace 20.

The graphite heating element 4 of the present graphitization furnace 20 includes:
Six outer circumferential grooves 22 forming clearance parts are cut along the axial direction of the outer circumference, and the six protrusions 23 with the grooves left in contact with the pipe 21 made of graphite material or graphite felt. pipe 2
1 is a sheath, a graphite heating element 4 is disposed and supported at a core position, and carbon powder 5 is packed around the outer periphery of the sheath. Note that since the inner diameter of the pipe 21 is larger than the outer diameter of the graphite heating element 4, a clearance 22 is formed. This clearance 22
is open on both sides as shown in the figure, one side is connected to the nitrogen inlet 7 and the other side is connected to the nitrogen outlet 8.
are connected to each other.

As shown, water-cooled electrodes 6 are attached to both ends of the heating element 4, and the heating element 4 is heated by passing current from one electrode to the other electrode.

During operation, nitrogen is supplied from the nitrogen inlet 7, and the cylindrical heating element 4 is supplied as shown by the arrow in FIG.
It is configured to actively flow not only into the cylinder 9 but also into the clearance 22 and be discharged from the outlet 8.

In the above device of the present invention, a case is shown in which a groove is cut on the outer periphery of the graphite heating element 4, but the fifth
The clearance 22 can also be created by a separate spacer 24, as shown in schematic longitudinal section.

Alternatively, instead of the carbon powder 5 which serves as both a heat insulating material and a supporting material in the device of the present invention, another lightweight heat insulating material, such as a suitable material in the form of felt, may be used for part or all of it. For example, since the weight of the heat insulating material applied to the innermost pipe 21 can be reduced, the number and arrangement of the protrusions 23 on the outer periphery of the graphite heating element 4 or the spacers 24 can be minimized. The convex portion 23 of the graphite heating element shown in FIG.
The spacer 24 shown in the figure is a graphite heating element 4.
It can also be done only at appropriate locations in the axial direction.

Furthermore, in the apparatus of the present invention, the clearance 22 is provided in the axial direction of the outer circumference of the graphite heating element 4, but it is not necessarily limited to the axial direction. For example, the spacer 24 may be formed in a ring shape, and It is also possible to form the clearance portion 22 by supporting the graphite heating element 4. The direction of nitrogen flow around the inner and outer peripheries of the graphite heating element 4 does not necessarily have to be parallel; it is also possible to make them face each other, or to let the nitrogen flow through one of the inner and outer peripheries of the graphite heating element 4 and then circulate it to the other.

[Example] By using the high-temperature heating device according to the present invention described above, surprising effects beyond expectations could be achieved as seen in the following Examples.

Comparative Example 1 In the conventional graphitization furnace 10 shown in FIG.
When 99.999% nitrogen was set at a flow rate of 8/min and continuously operated day and night, the graphite heating element 4 became unusable after 17 days. Fig. 2 shows a schematic cross-sectional view of the graphite heating element 4 after use, and a markedly worn part 4' can be seen on the outer periphery near the highest temperature part, and the amount of wasted amount reaches 2 kg (approximately 15% of the total weight). was.

Example 1 Using the graphitization furnace 20 according to the present invention shown in FIG.
℃, and the flow rate of 99.999% pure nitrogen was set at 15/min, and the life of the graphite heating element 4 was surprisingly extended to 110 days when it was operated continuously day and night.

In the embodiments described above, the case of a Tammann furnace for producing graphitized fibers has been described, but the purpose of the high-temperature heating device is not necessarily limited, and the gist of the present invention can be widely applied. . Moreover, the heating means and apparatus can be widely applied as long as it is a high-temperature heating apparatus using carbon or graphite as a heating element.
Alternatively, the inert gas to be supplied is not limited to nitrogen, and can be appropriately selected depending on the purpose.

[Effects] As explained above, the carbon fiber manufacturing apparatus of the present invention includes a pipe having an inner diameter larger than the outer diameter of the heating element and made of graphite or carbon between the heat insulating material and the heating element. The pipe is provided at a position where the sheath is the heating element and the heating element is the core, and both sides of the gap formed between the pipe and the heating element are opened, and one side of the opening is connected to the inert gas inlet, Since the other side of the opening is configured to communicate with the inert gas discharge port, the atmospheric temperature on the inner and outer surfaces of the heating element can be lowered within an appropriate range, thereby preventing evaporation of the heating element. This significantly extends the life of the heating element, which was conventionally short-lived, and greatly contributes to improving the production efficiency of the heating equipment, which is the objective, and furthermore, to reducing the cost of the production items that are the objective. It's something you get.

Further, when the filling insulation material is carbon or graphite powder, the pipe forming the clearance section supports it, so that the heating element can be replaced without removing the powder.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of a conventionally used Tammann furnace for producing graphitized fibers, and Figure 2 shows the state of the graphite heating element 4 used in the Tammann furnace shown in Figure 1 after use. 3 is a schematic cross-sectional view showing an embodiment of the Tammann furnace shown in FIG. 1 modified according to the present invention; FIG. 4 is a schematic vertical cross-sectional view of the Tammann furnace shown in FIG. 3. side view,
FIG. 5 shows a schematic longitudinal sectional view of a different embodiment of the Tammann furnace shown in FIG. 1: Carbonized thread, 1': Graphitized thread, 2: Nippuro roller, 3: Nippuro roller, 4: Graphite heating element, 4': Graphite heating element wear part, 5: Carbon powder, 6: Water-cooled electrode, 7: Nitrogen inlet,
8: Nitrogen outlet, 9: Inside of graphite heating element,
10: Conventional graphitization furnace, 20: Modified graphitization furnace, 21: Pipe, 22...Clearance part, 2
3: Convex portion of graphite heating element, 24: Spacer.

Claims (1)

[Claims] 1. A cylindrical heating element made of graphite or carbon, electrodes provided at both ends of the heating element, a heat insulating material provided around the outer periphery of the heating element, and a cylindrical heating element provided on one side of the heating element and communicating with the inside of the cylinder. an inert gas inlet;
In a carbon fiber manufacturing apparatus comprising an inert gas discharge port provided on the other side of the heating element and communicating with the inside of the cylinder, the space between the heat insulating material and the heating element has an inner diameter larger than the outer diameter of the heating element. , and a pipe made of graphite or carbon is provided at a position where the pipe is a sheath and the heating element is the core, and both sides of the gap formed between the pipe and the heating element are opened,
A carbon fiber manufacturing apparatus characterized in that one side of the opening communicates with the inert gas inlet and the other side of the opening communicates with the inert gas outlet.