JPH0635585B2 - Pitch heating device for carbon fiber manufacturing - Google Patents

Description

The present invention relates to a heating device for a carbon fiber manufacturing pitch.

(Prior Art) As is well known, when carbonaceous raw materials such as heavy oil, tar, and pitch are heated to 350 to 500 ° C., they are optically polarized under polarized light having a particle diameter of several microns to several hundreds of microns. Small spheres exhibiting anisotropy are generated. Then, upon further heating, these small spheres grow and coalesce, and finally the whole becomes a state exhibiting optical anisotropy. This anisotropic structure is formed by stacking and orienting high molecular weight aromatic hydrocarbons produced by a thermal polycondensation reaction of a carbonaceous raw material in layers, and is regarded as a precursor of a graphite crystal structure.

Such a heat-treated product is generally referred to as a mesophase-containing pitch, which is melt-spun, infusibilized, carbonized, and optionally graphitized through a spinneret to obtain high strength,
Pitch-based high-performance carbon fibers having characteristics such as high elastic modulus can be obtained, and thus they have been proposed as a raw material.

Carbon fiber is a material with a high specific strength and a high specific elastic modulus, and has been the focus of attention as a filler fiber for high-performance composite materials. Among them, Pitch-based high-performance carbon fiber has a large yield in the carbonization process, It has various advantages over polyacrylonitrile-based carbon fiber such as high rate.

In the case of heating the pitch in order to obtain the above-mentioned mesophase-containing pitch, conventionally, it has been carried out by a method of directly heating by a fire such as a burner or a method of heating by providing an electric heater or the like on the outer peripheral portion of the pitch heating device.

(Problems to be Solved by the Invention) However, in such a heating method, local heating is likely to occur, a difference occurs in the thermal history of the pitches depending on the site, and it is difficult to uniformly heat the pitched caulks. It was

(Means for Solving the Problems) Therefore, as a result of intensive investigations by the present inventors to solve such problems, as a result of heating the pitch in a heating zone having a uniform temperature distribution, the above-mentioned problems are solved. The inventors have found that they have been solved and have reached the present invention.

That is, an object of the present invention is to provide a heating device in which the pitch is heated uniformly without any difference in the thermal history of the pitch depending on the part.

The object is easily achieved by a heating device for a carbon fiber manufacturing pitch, in which a conduit through which the pitch flows is arranged in a heating zone in which the solid powder is flowing.

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

FIG. 1 is a schematic vertical sectional view showing an embodiment of the apparatus of the present invention. 1 is a heating device main body, 2 is a heating conduit, 3 is a pitch inlet, 4 is a pitch outlet, 5 is a heating zone, 6 is solid powder, 7 is a gas inlet, 8 is a gas outlet, 9 is a perforated plate,
Reference numeral 10 is a solid powder outlet, 11 is gold steel, and 12 is a sheath heater.

Here, the solid powder 6 is fluidized by air, nitrogen, waste gas, etc. taken in from the gas introduction port 7, and is further heated by the sheath heater 12 provided on the outer peripheral portion of the heating device main body 1 to open the heating zone 5. Is forming. Solid powder used 6
Is a solid powder having a high specific heat and a low pulverization rate, and specifically sand, alumina, iron oxide, copper powder, aluminum powder, and iron powder are used. Moreover, the particle size of the solid powder 6 may be such that it can flow, and is usually 5 to 100 mesh.
It is preferable to use one having about 10 to 50 mesh.

The solid powder 6 is fluidized by the gas introduced from the lower part of the heating device 1, but a porous plate 9 is provided in the lower part of the heating device 1 so that the solid powder 6 is not discharged into the device. The linear velocity of the gas in the porous plate 9 is an important factor in fluidizing the solid powder 6.

This gas linear velocity must be higher than the final settling velocity of the solid powder. The size of the solid powder 6 varies depending on the density and particle size of the solid powder 6, but in the case of alumina having a particle size of about 1 mm, it may be about 0.4 to 10 m / sec. When it is less than 0.4 m / sec, the fluidization of the solid powder 6 is not sufficient, and when it is 10 m / sec or more, the solid powder 6 is discharged from the upper part of the heating device 1, which is not preferable. In order to maintain a proper fluidized state, it is preferably about 1.1 to 2 times the final sedimentation rate of the solid powder. In order to prevent the solid powder 6 from being discharged to the outside of the device, it is preferable to enlarge the diameter of the upper part of the heating device 1 to provide a space, and to prevent entrainment of solid powder particles by providing gold steel at the gas outlet. Good to do.

The diameter of the enlarged portion is not particularly limited,
It is preferable that the linear gas velocity in the expanded portion be equal to or lower than the flow initiation velocity of the solid powder. Further, the pitch targeted by the present invention is a pitch for hydrogenation treatment or a pitch for mesolysis treatment, and the heating temperature of the heating zone 5 is variously selected according to the purpose. For example, a range of 200 to 400 ° C. is selected for hydrogenation treatment, or a range of 350 to 400 ° C. for meso-formation treatment. The heating means of the heating zone 5 is performed by a sheath heater 12 provided on the outer peripheral portion of the device, but it is preferable to introduce air nitrogen, waste heat gas and the like heated to the above temperature from the lower part of the device together with the heating by the sheath heater 12. Good to do. Further, it is desirable that the solid powder 6 is previously heated by an electric heater. When the heating temperature of the heating zone is relatively low at 200 to 300 ° C., the heating by the sheath heater is not always necessary and sensible heat of only the heating gas is sufficient. The method for disposing the heating conduit 2 is not particularly limited as long as it does not adversely affect the heating of the pitch, but it is preferable to dispose the heating conduit 2 in a linear shape to increase the heating area.

The shape of the heating conduit 2 is not particularly limited, either.
The cross-sectional shape may be circular, square, or the like as long as it does not hinder the flow of the pitch. The gas derived from the heating zone can be reheated as needed and reused as a flowing gas. The gas flow needs to be selected from an appropriate range in consideration of the linear velocity for fluidization and the heat balance of the heating zone. This is because if a large amount of low-temperature gas is introduced, a sufficient heating atmosphere cannot be created.

Also, the amount of solid powder is preferably such that the powder in the fluidized state covers the entire heating conduit. If the amount is too small, the heating is not sufficient, and if the amount is too large, it is useless and causes dissipation. Since the height of the fluidized bed is about 1.2 to 3 times the height of the stationary bed, the filling amount of the powder is appropriately selected in consideration of the density, particle size, gas linear velocity, etc. of the solid powder. For sand, alumina, aluminum powder, etc., the filling amount is 200
~1000kg / m ^3, preferably 300~800kg / m ³
In the case of iron powder and copper powder, 800-5000 kg /
m ³ , preferably about 1000 to 3000 kg / m ³ .

(Effect) According to the present invention, the pitch can be heated uniformly,
Further, the heating temperature can be controlled easily and precisely.

It also has the advantage that high temperatures can be easily achieved and maintained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of the fluidized-bed heating apparatus of the present invention. 1: Main body of heating device 2: Heating conduit 3: Pitch inlet port 4: Pitch outlet port 5: Heating zone, 6: Solid powder 7: Gas inlet port, 8: Gas outlet port 9: Perforated plate, 10: Solid powder Withdrawal port 11: Gold steel, 12: Sheath heater 13: Preferable fluidizing surface

Claims (4)

[Claims] 1. A heating device for a carbon fiber manufacturing pitch, wherein a conduit through which the pitch flows is arranged in a heating zone in which the solid powder is flowing. 2. The solid powder is sand, alumina, iron oxide, copper powder,
The device according to claim 1, wherein the device is aluminum powder or iron powder. 3. Device according to claim 1, characterized in that the upper part of the heating zone is enlarged. 4. A device according to claim 1, characterized in that the heating source of the heating zone is an electric heater.