JP2545079B2 - Equipment for vapor grown carbon fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an apparatus for producing a vapor grown carbon fiber capable of efficiently producing carbon fiber.

[Conventional technology]

The vapor-grown carbon fiber produced in the reaction space is a fiber having a diameter of 0.2 to 0.6 μm and a length of several hundreds of μm, and is a normal carbon fiber having strength, electrical conductivity, thermal conductivity and the like. It has the advantage that it can be manufactured inexpensively by mass production.

Conventionally, as shown in FIG. 3, a vapor grown carbon fiber is a gas obtained by passing a carrier gas 2 through a hydrocarbon 1, a transition metal powder serving as a seed, or a transition metal organic material that is thermally decomposed to produce a seed. It is manufactured by a method in which a gas obtained by mixing a compound 3 with a carrier gas 2 is introduced into a tubular reaction furnace (hereinafter referred to as a furnace) 4 heated by a heater 4a and thermally decomposed.

[Problems to be solved by the invention]

By the way, in the conventional manufacturing method, the vapor grown carbon fiber (hereinafter referred to as fiber) 5 which is decomposed and generated in the furnace and passed through the furnace together with the gas is guided to the collector 6 provided with the filter 6a which communicates to the outside, The gas is released through the filter 6a and the fiber 5
Have been collected. However, the generated fibers adhere to the inner wall of the furnace and block the furnace. Therefore, the operation had to be stopped and the carbons adhering to the furnace wall had to be removed, resulting in poor productivity.

In order to solve the above problems, the present inventors first forcedly send the produced fiber 5 in the furnace in the outlet direction of the furnace.
A ring-shaped scraping rod 7 shown by a chain double-dashed line that does not hinder the passage of gas is built in, and this is vertically moved up and down to release the bridging of the fiber 5 to prevent the furnace from being blocked and enable continuous operation. We proposed a device (Japanese Utility Model Sho 60-186434). By this method, it was possible to greatly extend the interval between continuous fiber production without stopping the operation.

However, in the fiber production process, the seeds contained in the raw material gas remain as they are, or the seeds produced by thermal decomposition adhere to the furnace wall or the fibers formed on the furnace wall, and the fibers grow from this. . Further, in the CVD method, a part of hydrocarbons becomes pyrolytic carbon (hereinafter referred to as PC) and adheres to the furnace wall and fibers grown on the furnace wall.

The layer to which the PC adheres is porous because fibers are mixed, but it is relatively hard and difficult to remove with the scraping rod 7. Therefore, as shown in FIG. 4, not only the PC deposition layer 8 is formed around the place where the thermal decomposition of the furnace 4 is severe and the thickness gradually increases and the scraping function is impaired. The passage is hindered, and the external heat is difficult to be transferred to the furnace, so that the fiber production efficiency is lowered. Even if the PC deposition layer 8 is removed, it becomes a lump and is separated from the furnace wall and collected. 6, the quality of the product is degraded.

Therefore, even in the method using a device with a built-in scraping device, although the interval is remarkably long, it is necessary to stop the operation almost regularly, open the furnace, and remove the PC layer adhered and grown on the furnace wall. There wasn't.

As a result of earnest studies to obtain a more efficient fiber production apparatus, the present inventors removed the deposited PC layer while it was thin and sent it to a collector to suppress the deterioration of product quality. It was discovered that it will be done.

The present inventor has been made on the basis of the above findings, and an object of the present invention is to provide an E manufacturing apparatus for fibers, which can efficiently and continuously manufacture fibers, and in which product quality hardly deteriorates.

[Means for solving problems]

The present invention has been made to achieve the above-mentioned object, and its gist is to flow a raw material gas containing a hydrocarbon or the like from one side of a tubular reactor, to thermally decompose it in a heating zone to generate carbon fiber, and to generate carbon fiber from the other side. A device for producing a vapor grown carbon fiber for taking out fibers, wherein the producing device removes pyrolytic carbon deposited on the inner wall of the tubular reactor while maintaining its temperature without opening the tubular reactor. A scraping machine for scraping and removing, the scraping machine can be freely inserted into and withdrawn from the tubular reactor, and also has an extensible rotary shaft that is driven to rotate and a base portion of the extensible rotary shaft at a tip peripheral portion thereof. A gas phase characterized by having a scraping needle for scraping the pyrolytic carbon deposited on the inner wall of the tubular reactor, the tip end of which is radially opened by centrifugal force with the rotation of the telescopic rotary shaft. There is a method of manufacturing carbon fiber.

FIG. 1 is a longitudinal sectional view showing an example of the device of the present invention.
The same parts as those in the figure are designated by the same reference numerals and the description thereof will be omitted.

At the inlet end of the furnace 4, a pocket 11 concentric with the furnace 4 is opened in the furnace 4 and is airtightly attached.
A scraping machine 12 is housed inside.

The scraping machine 12 penetrates the upper surface of the pocket 11 in an airtight manner, and as shown in FIG. 2, is attached so that it can be inserted into and pulled out from the central axis of the furnace 4, and is rotationally driven at a speed of several hundred rotations / minute. The expansion / contraction rotary shaft 13, the base of which is attached to the distal end peripheral portion of the expansion / contraction rotary shaft 13 so as to be rotatable in the radial opening direction, and has a length of about 3/5 of the inner diameter of the furnace 4 and a scraping needle 14 It is composed by.

To produce fibers using the furnace 4, the furnace is heated to a predetermined temperature and a raw material gas is introduced. The raw material gas is thermally decomposed to generate fibers, and the accumulated material in the furnace is scraped off at regular intervals by the scraping rod 7. Since the PC layer gradually grows during that time, the expansion / contraction rotary shaft 13 is rotationally driven and extended while the layer of the PC precipitation layer is thin. The scraping needle 14 is opened by centrifugal force and gradually descends while scratching the inner peripheral surface of the furnace 1. In the process, the PC deposition layer is a scraping needle.
It is scraped off by the tip of 14 and becomes fine powder,
It is removed, falls down, and enters the collector, but its amount is small, and the quality of the product is hardly deteriorated.

Further, since the scraping machine 12 does not interfere with the passage of the raw material gas, the operation may be continued as it is. But,
If necessary, the supply of hydrocarbons, seeds or seed material gas may be stopped, but it is not necessary to lower the temperature of the furnace 4, and even if the gas supply is temporarily stopped, after scraping is completed. Since the operation can be started immediately, the decrease in efficiency is extremely small. After scraping, the scraping machine 12 is housed in the pocket 11 and stands by until the next scraping.

In this way, at intervals according to the formation state of the PC deposit layer, the scraper 12 is operated to scrape the PC deposit layer, so that the furnace wall is always kept in a state in which there is almost no PC deposit layer, and the efficiency is improved. Fiber is often produced.

〔Example〕

 Next, the present invention will be described with reference to Examples and Comparative Examples.

Example 1 Using the apparatus shown in FIG. 1, the scraping bar 7 is driven at any time, and only the feeding of the raw material gas is stopped every 30 minutes without lowering the temperature of the furnace, and the scraping machine 12 is operated at 300 to 500 rpm. Driven by a PC
The deposited layer was removed. At this time, while the scraping machine 12 is being driven, the scraping bar 7 is pulled up to the top so as not to interfere with the scraping. As a result, steady operation could be performed immediately after the scraping was completed. In this way, continuous operation was carried out for 2 days, but no decrease in fiber yield was observed.

Example 2 A fiber was synthesized in the same manner as in Example 1 except that the supply of the raw material gas was not stopped, and the same results as in Example 1 were obtained in the continuous operation for 2 days.

Comparative Example 1 A fiber was synthesized in the same manner as in Example 1 except that the scraper 12 was not used. As a result, a decrease in yield was observed 12 hours after the start of operation. In order to recover this,
Although the PC deposition layer was removed, it took about 2 hours from the stop of operation to the start of operation, and the operation efficiency dropped significantly.

(Effect of the invention) As described above, the apparatus of the present invention, the PC deposition layer to be formed, while thin, the furnace is opened, or completely removed without lowering the temperature, yield, production efficiency Since it does not deteriorate and fibers are produced at low cost, it is an excellent device that can greatly expand the field of use of carbon fibers.

[Brief description of drawings]

FIGS. 1 and 2 show an example of the apparatus of the present invention. FIG. 1 is a partial longitudinal sectional view, FIG. 2 is an enlarged side view of a scraper, and FIG. 3 is an example of a conventional furnace. 4 is a vertical sectional view showing
The figure is a vertical cross-sectional view showing the deposition state of the PC deposition layer. 1 ... Hydrocarbon, 2 ... Carrier gas, 3 ... Seed or seed raw material, 4 ... Tubular reactor (furnace), 4a ... Heater, 5 ... Vapor grown carbon fiber (fiber), 6 ... Collector, 6a ... filter, 7 ... scraping rod, 8 ... PC deposit layer, 11 ... pocket, 12 ... scraper, 13 ... extendable rotary shaft, 14 ... scraping needle.

Claims (1)

(57) [Claims] 1. Production of a vapor grown carbon fiber in which a raw material gas containing a hydrocarbon or the like is caused to flow from one side of a tubular reaction furnace, pyrolysis is carried out in a heating zone to produce carbon fiber, and the carbon fiber is taken out from the other side. An apparatus, wherein the manufacturing apparatus comprises a scraper for scraping and removing the pyrolytic carbon deposited on the inner wall of the tubular reactor while maintaining the temperature thereof without opening the tubular reactor. The machine can be inserted into and withdrawn from the tubular reactor, and the telescopic rotary shaft that is driven to rotate and its base portion are attached to the distal end peripheral portion of the telescopic rotary shaft. Its tip opens radially due to centrifugal force,
An apparatus for producing a vapor grown carbon fiber, comprising: a scraping needle for scraping pyrolytic carbon deposited on the inner wall of a tubular reactor.