JP2009243008A - Carbonizing furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbonizing furnace which permits a pyrolysis gas to be smoothly extracted and exhibits a high production yield rate of high-quality carbon fibers, and its operating method. <P>SOLUTION: The carbonizing furnace 2 is made by forming three or more air outlets 10a, 10b, 10c, and 10d in a row in a width direction Lw within the range of 5 to 45% from the furnace with respect to the total length Lt of the furnace. The air outlets 10a, 10b, 10c, and 10d include a flow regulating valve. The ratio of the average flow rate of exhaust air in the air outlets 10b and 10c in a part other than both end sides from among the three or more air outlets 10a, 10b, 10c, and 10d formed in a row in the width direction of the furnace to the average flow rate of exhaust air in the air outlets 10a and 10d on both end sides is preferably 0.90 to 1.10 times. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a carbon fiber firing furnace (carbonization furnace) for carbonizing a flame resistant fiber in the production of carbon fiber.

  In the method of producing pitch-based or polyacrylonitrile (PAN) -based carbon fibers, flame retardant treatment is performed while stretching or shrinking the bundled strand-shaped raw material fibers in an oxidizing atmosphere at 200 to 300 ° C. Obtain flame resistant fibers.

  Next, the flame-resistant fiber is guided to a carbonization furnace at 400 ° C. or higher in an inert gas atmosphere, and is first carbonized at 400 to 800 ° C. as necessary, and then second carbonized at 1000 ° C. or higher. Carbonization is performed by firing.

  In the carbonization furnace, a large amount of gas (pyrolysis gas) is generated along with the carbonization, and 10 to 40% by mass of the flameproof fiber strand supplied to the carbonization furnace is gasified. This gas passes through the exhaust duct together with the inert gas and is discharged out of the furnace.

  In a carbonization furnace, when carbonizing strands that run horizontally in the furnace, the pyrolysis gas spreads along the ceiling (upper wall) of the furnace. This pyrolysis gas is usually extracted from an exhaust port provided in the upper wall of the carbonization furnace, and then exhausted outside the system through an exhaust duct.

  However, a considerable amount of the pyrolysis gas cannot be smoothly extracted from the carbonization furnace, and a part of the pyrolysis gas stays in the carbonization furnace. This staying gas touches a wall surface such as an upper wall in the furnace, and a part thereof adheres to the wall surface as a liquid foreign substance such as condensed tar.

  When the strand is oil-treated with a sizing agent such as silicone oil, solid foreign matters such as silica powder generated by thermal decomposition are generated. A part of the solid foreign matter adheres to the surface of the liquid foreign matter and accumulates on the wall surface in the furnace as a solid-liquid mixed foreign matter.

  The solid-liquid mixed foreign matter deposited on these wall surfaces, particularly the upper wall, becomes a high density as the amount of deposition increases, falls on the strands, and becomes a solid-liquid mixed foreign matter that contaminates the strands. These solid-liquid mixed foreign substances not only lower the quality of the strand but also cause the strand to be cut, resulting in a reduction in the product rate.

  Various proposals have been made so that the pyrolysis gas can be smoothly extracted from the carbonization furnace (see, for example, Patent Documents 1 and 2).

  In Patent Document 1, slit-like exhaust ports that open over the entire width of the furnace (full width orthogonal to the fiber running direction) are formed at a plurality of positions in the furnace length direction, such as a position where the set temperature of the upper wall is the highest. A carbonization furnace is disclosed.

  Patent Document 2 discloses a carbonization furnace having an exhaust port in addition to the upper position. Further, it is disclosed that a pool portion having a cross-sectional area larger than that of the exhaust pipe is provided downstream of a portion where the exhaust port is opened.

Note that Patent Document 1 does not specifically indicate where the installation position of the exhaust port is suitable in the furnace length direction. Patent Document 2 describes that the shape of the exhaust port is not limited but that a slit shape is preferable, and does not specifically indicate what the shape of the exhaust port is suitable. Moreover, in any of the carbonization furnaces disclosed in Patent Documents 1 and 2, it is not sufficient to smoothly extract the pyrolysis gas and improve the product rate.
JP 2002-294521 A (Claims) JP 2007-262602 A (Claims)

  The present inventor has been diligently examining the above problems, and the reason why the pyrolysis gas generated in the conventional carbonization furnace is not smoothly discharged is that the reverse flow of the pyrolysis gas from the high temperature side to the low temperature side or the furnace It was thought that the internal stagnation occurred and the condensed tar adhered to the wall surface in the furnace, which dropped and caused strand contamination, causing a process trouble.

  Therefore, when examining the flow of pyrolysis gas, it was discovered that the linear velocity of the exhaust near the side wall of the carbonization furnace was lower than expected. From this, the installation position of the exhaust port in the furnace length direction of the upper wall of the carbonization furnace is set to one predetermined position, the number of exhaust ports is set to 3 or more in the furnace width direction, and the opening ratio of each exhaust port is set to When equipped with a flow control valve that can be adjusted, the linear velocity distribution of the exhaust at each exhaust port becomes uniform, the pyrolysis gas can be extracted smoothly, and the product rate of carbon fiber of good quality increases. As a result, the present invention has been completed.

  Accordingly, an object of the present invention is to provide a carbonization furnace and an operation method thereof that solve the above-described problems.

  The present invention for achieving the above object is described below.

  [1] Three or more exhaust ports are formed in a row in the furnace width direction in a range of 5 to 45% from the outlet with respect to the entire length of the furnace, and the exhaust port includes a flow rate adjusting valve. Characterized carbonization furnace.

  [2] Three or more exhaust ports formed in a row in the furnace width direction, and the ratio of the average exhaust gas flow velocity at the exhaust ports other than both ends to the average exhaust gas flow velocity at the both exhaust ports is 0.90 to 1. The operation method of the carbonization furnace as described in [1] which is 10 times.

  In the carbonization furnace of the present invention, the installation position of the exhaust port in the furnace length direction of the upper wall of the furnace is only one predetermined position of 5 to 45% from the outlet with respect to the entire length of the furnace, and the number of exhaust ports is the number of the exhaust ports. Three or more in the width direction and each exhaust port is equipped with a flow control valve that allows the opening rate of each exhaust port to be adjusted. The product rate will be higher.

  Hereinafter, the present invention will be described in detail with reference to FIGS.

  FIG. 1 is a schematic view showing an example of a carbonization furnace of the present invention, (A) is a plan view thereof, (B) is a side view thereof, and (C) is a front view thereof. .

  In FIG. 1, 2 is a carbonization furnace. A plurality of (8 in the figure) flame-resistant fiber strands 4 subjected to flame resistance treatment in a flame resistance treatment apparatus (not shown) are placed horizontally in the carbonization furnace 2 heated to 400 ° C. or higher. It runs parallel to the side wall 6 of the furnace 2 and is carbonized into carbon fibers.

  The carbonization furnace 2 is subjected to a first carbonization treatment in a first stage carbonization furnace heated to 400 to 800 ° C. as it goes from the entrance side to the exit side of the strand 4 as necessary, and further in the second stage. You may comprise with the two-stage carbonization furnace which carries out the second carbonization process with a two-carbonization furnace. In the case of a two-stage carbonization furnace, the carbonization furnace 2 is preferably used in the first stage carbonization furnace.

  In the upper wall (ceiling) 8 of the furnace 2, three or more (four in the figure) of three or more are provided in order to discharge the pyrolysis gas generated by the carbonization treatment of the strand 4 from the furnace 2 to the outside. Exhaust ports 10a, 10b, 10c, and 10d are provided. The number of exhaust ports is preferably 3 to 10, more preferably 3 to 5. These exhaust ports 10a, 10b, 10c, and 10d are provided with a row of exhaust ports having substantially the same shape in the furnace width Lw direction in a range of 5 to 45% from the outlet with respect to the entire length Lt of the furnace.

  That is, in the range of 5 to 45%, the length in the furnace length direction from the outlet of the furnace 2 to the exhaust ports 10a, 10b, 10c, and 10d is Lo, and from the inlet of the furnace 2 to the exhaust ports 10a, 10b, 10c, and 10d. When the length in the furnace length direction is Li, the ratio of the length Lo in the furnace length direction from the outlet of the furnace 2 to the exhaust ports 10a, 10b, 10c, and 10d (Lo / Lt) with respect to the furnace total length Lt is there.

  Each of the exhaust ports 10a, 10b, 10c, and 10d is provided with a flow rate adjusting valve that can adjust the opening ratio of each exhaust port. The shape of the exhaust port is not particularly limited, but a rectangular shape is preferable for easy adjustment of the aperture ratio. The exhaust ports do not need to have the same dimensions, and each exhaust port can be formed with various dimensions. However, the length of each exhaust port in the furnace width direction is preferably the same in terms of operation.

  The ratio of the exhaust port opening ratio is 0.90 to 1.10 times, preferably 0.95, as the ratio of the exhaust average flow velocity at the exhaust ports 10b and 10c at both ends to the exhaust average flow velocity at the exhaust ports 10a and 10d at both ends. It is preferable to adjust the aperture ratios of the exhaust ports 10a, 10b, 10c, and 10d so as to be ˜1.05 times. The ratio of the total length of the exhaust ports 10a, 10b, 10c, and 10d in the furnace width direction to the furnace width Lw is preferably 75 to 98%. The exhaust ports on both ends indicate one recent exhaust port on each side wall.

  Connection pipes 11a, 11b, 11c, and 11d are connected to the peripheral edges of the exhaust ports 10a, 10b, 10c, and 10d. Although the cross-sectional shape of the connecting cylinder is not particularly limited, the connecting cylinder preferably has a rectangular cross-sectional shape in order to match the preferable rectangular shape of the exhaust port. That is, the shape of the connecting tube is preferably a square tube.

  The upper ends of the connecting cylinders 11a, 11b, 11c, and 11d are connected to the exhaust gas transfer main duct 14. The cross-sectional shape of the exhaust gas transfer main duct 14 is preferably a rectangle that is long in the furnace width direction and short in the furnace length direction.

  In FIG. 1, Hf is the height of the carbonization furnace 2, and Hs is the height of the connecting cylinders 11a, 11b, 11c, and 11d.

  With the above configuration, the pyrolysis gas generated in the furnace 2 smoothly travels toward the exhaust ports 10a, 10b, 10c, and 10d at the shortest distance and is connected from the exhaust ports 10a, 10b, 10c, and 10d. It enters the cylinders 11a, 11b, 11c, 11d, and further passes through the exhaust gas transfer main duct 14 and is discharged as exhaust gas 16 outside the system.

  In addition, since the pyrolysis gas rarely touches the wall surface, particularly the upper wall, the solid-liquid mixed foreign matter resulting from the pyrolysis gas is reduced from adhering and depositing on the wall surface, particularly the upper wall, and strand contamination, Cutting and deterioration can be prevented, and the product rate of good quality carbon fibers increases.

  Hereinafter, although the carbonization furnace of this invention is demonstrated using an Example and a comparative example, this invention is not limited to these Examples and a comparative example.

  In addition, about the product rate of the carbon fiber of good quality, the carbon fiber with less than 0.5 spots contaminated by solid-liquid mixed foreign matter per 100 m in length of the carbon fiber strands bundled in 10 pieces has good quality. The carbon fiber was evaluated based on the mass ratio of the good quality carbon fiber to the total amount of carbon fiber produced.

Example 1
Carbon fiber was manufactured using the carbonization furnace 2 shown in FIG. In the carbonization furnace 2, the space in the furnace 2 was a width Lw: 4000 mm, a length Lt: 7000 mm, and a height Hf: 200 mm.

  The length of the upper wall of the furnace 2 from the outlet side is 2500 mm, the length Li from the inlet side is 4500 mm, and the length ratio Lo / Lt is 36%. Four rectangular exhaust ports 10a, 10b, 10c, and 10d (width direction length) were provided in one row in the furnace width direction (each 200 mm interval). The ratio of the total length of the exhaust ports 10a, 10b, 10c, and 10d in the furnace width direction to the furnace width Lw was 80%.

  The aperture ratio after adjusting the aperture ratio of each exhaust port is 100% for the exhaust ports 10a and 10d on both ends, and 95% for the exhaust ports 10b and 10c other than both ends. there were. The ratio of the average exhaust flow velocity at the exhaust ports 10b, 10c other than the opposite ends to the average exhaust flow velocity at the exhaust ports 10a, 10d on both ends was 1.02.

  The heights Hs of the connecting cylinders 11a, 11b, 11c, and 11d connected to the peripheral edges of the exhaust ports 10a, 10b, 10c, and 10d were all 150 mm.

  The cross-sectional dimension and shape of the exhaust gas transfer main duct 14 connected to the respective upper ends of the connecting cylinders 11a, 11b, 11c, and 11d were 100 mm (length in the furnace length direction) × 3800 mm (length in the furnace width direction) rectangle. .

  In the carbonization furnace 2 configured as described above, the pyrolysis gas enters the connection cylinders 11a, 11b, 11c, and 11d through the exhaust ports 10a, 10b, 10c, and 10d, and further passes through the exhaust gas transfer main duct 14 to the outside of the system. 16 was discharged.

  After 14 days of operation, there is almost no foreign matter such as tar and silica powder in the furnace 2, the connecting cylinders 11a, 11b, 11c, 11d, and the exhaust gas transfer main duct 14, and the product rate is 96%. there were.

Example 2
In the carbonization furnace 2 shown in FIG. 1, except that the opening ratios at the exhaust ports 10a and 10d on both ends are 100%, and the opening ratios at the exhaust ports 10b and 10c other than both ends are 70%, The carbonization furnace was operated in the same manner as in Example 1 to produce carbon fibers.

  The ratio of the average exhaust flow velocity at the exhaust ports 10b, 10c other than the opposite ends to the average exhaust flow velocity at the exhaust ports 10a, 10d on both ends was 0.95 times.

  After 14 days of operation, there is almost no foreign matter such as tar and silica powder in the furnace 2, the connecting cylinders 11a, 11b, 11c, 11d, and the exhaust gas transfer main duct 14, and the product rate is 95%. there were.

Example 3
Carbon fiber was manufactured using the carbonization furnace 12 shown in FIG. In the carbonization furnace 12, the space in the furnace 12 was a width Lw: 4000 mm, a length Lt: 7000 mm, and a height Hf: 200 mm.

  The length of the upper wall of the furnace 12 from the outlet side is 2500 mm, the length Li from the inlet side is 4500 mm, and the length ratio Lo / Lt is 36% at a position of 100 mm (length in the furnace length direction) × 1200 mm (furnace Three rectangular exhaust ports 13a, 13b, 13c (width direction length) were provided in one row in the furnace width direction (each 100 mm interval). The ratio of the total length of the exhaust ports 13a, 13b, 13c in the furnace width direction to the furnace width Lw was 90%.

  Regarding the opening ratio after adjusting the opening ratio of each exhaust port, the opening ratios at the exhaust ports 13a and 13c on both ends were 100%, and the opening ratios at the exhaust ports 13b other than both ends were 95%. The ratio of the exhaust flow velocity at the exhaust ports 13b other than both ends to the exhaust average flow velocity at the exhaust ports 13a and 13c on both ends was 1.00 times.

  The heights Hs of the connecting cylinders 15a, 15b, 15c connected to the peripheral edges of the exhaust ports 13a, 13b, 13c were all 150 mm.

  The cross-sectional dimension and shape of the exhaust gas transfer main duct 17 connected to the respective upper ends of the connecting cylinders 15a, 15b, and 15c were rectangles of 100 mm (length in the furnace length direction) × 3800 mm (length in the furnace width direction).

  In the carbonization furnace 12 having the above configuration, the pyrolysis gas enters the connection cylinders 15a, 15b, and 15c from the exhaust ports 13a, 13b, and 13c, and further passes through the exhaust gas transfer main duct 17 and is discharged to the outside as the exhaust gas 18. It was.

  In addition, about another structure, the same referential mark as FIG. 1 is attached | subjected to the location similar to FIG. 1, and the description is abbreviate | omitted.

  After 14 days of operation, there was almost no foreign matter such as tar or silica powder in the furnace 12, the connecting cylinders 13a, 13b, 13c, and the exhaust gas transfer main duct 17, and the product rate was 95%. .

Example 4
Carbon fiber was manufactured using the carbonization furnace 21 shown in FIG. This carbonization furnace 21 has the exhaust ports 10a, 10b, 10c, and 10d at positions where the length Lo from the outlet side is 500 mm, the length Li from the inlet side is 6500 mm, and the length ratio Lo / Lt is 7%. Except for the provision, it was the same as the carbonization furnace 2 shown in FIG.

  The aperture ratio after adjusting the aperture ratio of each exhaust port was 100% at the exhaust ports 10a and 10d on both ends, and 95% at the exhaust ports 10b and 10c other than both ends. . The ratio of the average exhaust flow velocity at the exhaust ports 10b, 10c other than the opposite ends to the average exhaust flow velocity at the exhaust ports 10a, 10d on both ends was 1.02.

  In the carbonization furnace 21 configured as described above, the pyrolysis gas enters the connection cylinders 11a, 11b, 11c, and 11d from the exhaust ports 10a, 10b, 10c, and 10d, and further passes through the exhaust gas transfer main duct 14 to the outside of the system. 16 was discharged.

  After 14 days of operation, there is almost no foreign matter such as tar or silica powder in the furnace 21, the connecting cylinders 11a, 11b, 11c, 11d, and the exhaust gas transfer main duct 14, and the product rate is 95%. there were.

Comparative Example 1
Carbon fiber was manufactured using the carbonization furnace 22 shown in FIG. In the carbonization furnace 22, the space in the furnace 22 was a width Lw: 4000 mm, a length Lt: 7000 mm, and a height Hf: 200 mm.

  Rectangular exhaust port of 100 mm (length in the furnace length direction) × 800 mm (length in the furnace width direction) at a position where the length La from the outlet side of the upper wall of the furnace 22 is 2500 mm and the length ratio La / Lt is 36% Four 24a, 24b, 24c, and 24d were provided in one row in the furnace width direction (each 200 mm interval). The ratio of the total length of the exhaust ports 24a, 24b, 24c, 24d in the furnace width direction to the furnace width Lw was 80%.

  A rectangular exhaust port 24e of 100 mm (length in the furnace length direction) × 800 mm (length in the furnace width direction) at a position where the length Lb from the position of this row is 1500 mm and the length ratio (La + Lb) / Lt is 57%, Four 24f, 24g, and 24h were provided in one row in the furnace width direction (each 200 mm interval). The ratio of the total length of the exhaust ports 24e, 24f, 24g, 24h in the furnace width direction to the furnace width Lw was 80%.

  The length Lc from the position of this row is 1500 mm, the length Ld from the inlet side is 1500 mm, and the length ratio (La + Lb + Lc) / Lt is 79% at a position of 100 mm (furnace length direction) × 800 mm (furnace width direction) Four (length) rectangular exhaust ports 24i, 24j, 24k, 24l are provided in one row in the furnace width direction (each 200 mm interval). The ratio of the total length of the exhaust ports 24i, 24j, 24k, 24l in the furnace width direction to the furnace width Lw was 80%.

  The aperture ratios after adjusting the aperture ratio of each exhaust port are 100% in the exhaust ports 24a, 24d, 24e, 24h, 24i, and 24l on both ends, and the exhaust ports 24b, 24c, The aperture ratios at 24f, 24g, 24j, and 24k were all 95%. The ratio of the exhaust average flow velocity at the exhaust ports 24b, 24c, 24f, 24g, 24j, 24k other than both ends to the exhaust average flow velocity at the exhaust ports 24a, 24d, 24e, 24h, 24i, 24l on both ends is 1.02 times. there were.

  Connecting cylinders 26a, 26b, 26c, 26d, 26e, 26f, 26g, 26h, connected to the peripheral edges of the exhaust ports 24a, 24b, 24c, 24d, 24e, 24f, 24g, 24h, 24i, 24j, 24k, 24l, The heights Hs of 26i, 26j, 26k, and 26l were all 150 mm.

  Cross-sectional dimensions and shapes of the exhaust gas transfer main duct 28a connected to the respective upper ends of the connecting cylinders 25a, 26b, 26c, and 26d, and cross-sectional dimensions and shapes of the exhaust gas transfer main ducts 28b connected to the respective upper ends of 26e, 26f, 26g, and 26h The cross-sectional dimension and shape of the exhaust gas transfer main duct 28c connected to the upper ends of the shapes, 26i, 26j, 26k, and 28l are all 100 mm (length in the furnace length direction) × 3800 mm (length in the furnace width direction) rectangle. there were.

  In the carbonization furnace 2 configured as described above, the pyrolysis gas is supplied from the exhaust ports 24a, 24b, 24c, 24d, 24e, 24f, 24g, 24h, 24i, 24j, 24k, 24l to the connecting cylinders 26a, 26b, 26c, 26d. , 26e, 26f, 26g, 26h, 26i, 26j, 26k, and 26l, and further discharged through the exhaust gas transfer main ducts 28a, 28b, and 28c as exhaust gases 30a, 30b, and 30c.

  In addition, about another structure, the same referential mark as FIG. 1 is attached | subjected to the location similar to FIG. 1, and the description is abbreviate | omitted.

  After 14 days of operation, in the furnace 22, in the connecting tubes 26a, 26b, 26c, 26d, 26e, 26f, 26g, 26h, 26i, 26j, 26k, 26l, and in the exhaust gas transfer main ducts 28a, 28b, 28c, Attachment of foreign matters such as tar and silica powder was observed, and the product rate was 92%.

Comparative Example 2
Carbon fiber was manufactured using the carbonization furnace 32 shown in FIG. In the carbonization furnace 32, the width Lw of the furnace 32 was 4000 mm, the length Lt was 7000 mm, and the height Hf was 200 mm.

  100 mm (length in the furnace length direction) × 3800 mm (furnace length) at the position where the length Lo from the outlet side is 2500 mm, the length Li from the inlet side is 4500 mm, and the length ratio Lo / Lt is 36%. One rectangular exhaust port 34 (length in the width direction) was provided. The ratio of the length of the exhaust port 34 in the furnace width direction to the furnace width Lw was 95%.

  The opening ratio of the exhaust port 34 is 100%, a connection cylinder 36 is connected to the periphery of the exhaust port 34, and an exhaust gas transfer main duct 38 is connected to the upper end of the connection cylinder 36. The dimensions and shape were a rectangle of 100 mm (length in the furnace length direction) × 3800 mm (length in the furnace width direction). Since the connection cylinder 36 and the exhaust gas transfer main duct 38 have the same cross-sectional dimensions and shape, there is substantially no boundary between the connection cylinder 36 and the exhaust gas transfer main duct 38.

  At the exhaust port 34, the exhaust flow velocity at the position of 500 mm from the side walls 6 toward the center in the furnace width direction is the same, and the ratio of the exhaust flow velocity at the center position in the furnace width direction to the exhaust flow velocity at these positions is 1.15 times.

  In the carbonization furnace 32 configured as described above, the pyrolysis gas enters the connection tube 36 from the exhaust port 34, and further passes through the exhaust gas transfer main duct 38 and is discharged as the exhaust gas 40 outside the system.

  In addition, about another structure, the same referential mark as FIG. 1 is attached | subjected to the location similar to FIG. 1, and the description is abbreviate | omitted.

  After operation for 14 days, foreign matter such as tar and silica powder is observed in the furnace 32, the connecting cylinder 36, and the exhaust gas transfer main duct 38 (particularly near both ends in the furnace width direction), and the product rate is 88. %Met.

Comparative Example 3
Carbon fiber was manufactured using the carbonization furnace 42 shown in FIG. In this carbonization furnace 42, the width Lw of the furnace 42 was 4000 mm, the length Lt was 7000 mm, and the height Hf was 200 mm.

  Rectangular exhaust port of 100 mm (length in the furnace length direction) × 3800 mm (length in the furnace width direction) at a position where the length La from the outlet side of the upper wall of the furnace 42 is 2500 mm and the length ratio La / Lt is 36% 44a was provided. The ratio of the length of the exhaust port 44a in the furnace width direction to the furnace width Lw was 95%.

  A rectangular exhaust port of 100 mm (length in the furnace length direction) × 3800 mm (length in the furnace width direction) at a position where the length Lb from the position of the exhaust port 44 a is 1500 mm and the length ratio (La + Lb) / Lt is 57% 44b was provided. The ratio of the length of the exhaust port 44b in the furnace width direction to the furnace width Lw was 95%.

  The length Lc from the position of the exhaust port 44b is 1500 mm, the length Ld from the inlet side is 1500 mm, and the length ratio (La + Lb + Lc) / Lt is 79% at a position of 100 mm (length in the furnace length) × 3800 mm (furnace A rectangular exhaust port 44c (length in the width direction) was provided. The ratio of the length of the exhaust port 44c in the furnace width direction to the furnace width Lw was 95%.

  The opening ratios of the exhaust ports 44a, 44b, 44c are all 100%, and the connection cylinders 46a, 46b, 46c are connected to the peripheral edges of the exhaust ports 44a, 44b, 44c, respectively. Exhaust gas transfer main ducts 48a, 48b, 48c are connected to the upper ends, respectively, and the cross-sectional dimensions and shapes of the exhaust gas transfer main ducts 48a, 48b, 48c are all 100 mm (length in the furnace length direction) × 3800 mm (furnace width) (Length in the direction). Since the connection cylinders 46a, 46b, 46c and the exhaust gas transfer main ducts 48a, 48b, 48c have the same cross-sectional dimensions and shapes, the connection cylinders 46a, 46b, 46c and the exhaust gas transfer main ducts 48a, 48b, 48c respectively. There are virtually no boundaries.

  In any of the exhaust ports 44a, 44b, 44c, the exhaust flow velocity at the position of 500 mm from the side walls 6 toward the center in the furnace width direction is the same, and the exhaust flow velocity at the center in the furnace width direction with respect to the exhaust flow velocity at these positions is the same. The ratio of the exhaust flow velocity at the position was 1.15 times.

  In the carbonization furnace 42 configured as described above, the pyrolysis gas enters the connection tubes 46a, 46b, 46c through the exhaust ports 44a, 44b, 44c, and further passes through the exhaust gas transfer main ducts 48a, 48b, 48c to the outside of the system. It was discharged as 50a, 50b, 50c.

  In addition, about another structure, the same referential mark as FIG. 1 is attached | subjected to the location similar to FIG. 1, and the description is abbreviate | omitted.

  After 14 days of operation, foreign substances such as tar and silica powder adhere to the furnace 42, the connecting cylinders 46a, 46b, 46c, and the exhaust gas transfer main ducts 48a, 48b, 48c (particularly near both ends in the furnace width direction). And the product rate was 85%.

Comparative Example 4
In the carbonization furnace 2 shown in FIG. 1, except that the opening ratios at the exhaust ports 10a, 10d on both ends are 100%, and the opening ratios at the exhaust ports 10b, 10c other than both ends are 100%, The carbonization furnace was operated in the same manner as in Example 1 to produce carbon fibers.

  The ratio of the average exhaust flow velocity at the exhaust ports 10b, 10c other than the opposite ends to the average exhaust flow velocity at the exhaust ports 10a, 10d on both ends was 1.12 times.

  After 14 days of operation, foreign matter such as tar and silica powder is observed in the furnace 2, the connecting cylinders 11 a, 11 b, 11 c, 11 d, and the exhaust gas transfer main duct 14 (particularly near both ends in the furnace width direction). The product rate was 90%.

Comparative Example 5
Carbon fiber was manufactured using the carbonization furnace 51 shown in FIG. In the carbonization furnace 51, the exhaust ports 10a, 10b, 10c, and 10d are placed at positions where the length Lo from the outlet side is 3500 mm, the length Li from the inlet side is 3500 mm, and the length ratio Lo / Lt is 50%. Except for the provision, it was the same as the carbonization furnace 2 shown in FIG.

  The aperture ratio after adjusting the aperture ratio of each exhaust port was 100% at the exhaust ports 10a and 10d on both ends, and 95% at the exhaust ports 10b and 10c other than both ends. . The ratio of the average exhaust flow velocity at the exhaust ports 10b, 10c other than the opposite ends to the average exhaust flow velocity at the exhaust ports 10a, 10d on both ends was 1.02.

  In the carbonization furnace 51 having the above configuration, the pyrolysis gas enters the connection cylinders 11a, 11b, 11c, and 11d through the exhaust ports 10a, 10b, 10c, and 10d, and further passes through the exhaust gas transfer main duct 14 to the outside of the system. 16 was discharged.

  After 14 days of operation, foreign matter such as tar and silica powder is observed in the furnace 51, the connecting cylinders 11a, 11b, 11c, 11d, and the exhaust gas transfer main duct 14 (particularly near both ends in the furnace width direction). The product rate was 93%.

Comparative Example 6
Carbon fiber was manufactured using the carbonization furnace 52 shown in FIG. In this carbonization furnace 52, the space Lw in the furnace 52 was 4000 mm, the length Lt was 7000 mm, and the height Hf was 200 mm.

  Rectangular exhaust port of 100 mm (length in the furnace length direction) × 800 mm (length in the furnace width direction) at the position where the length La from the outlet side of the upper wall of the furnace 52 is 500 mm and the length ratio La / Lt is 7% Four 54a, 54b, 54c, and 54d are provided in one row in the furnace width direction (each 200 mm interval). The ratio of the total length of the exhaust ports 54a, 54b, 54c, 54d in the furnace width direction to the furnace width Lw was 80%.

  A rectangular exhaust port 54e of 100 mm (length in the furnace length direction) × 800 mm (length in the furnace width direction) at a position where the length Lb from the position of this row is 2500 mm and the length ratio (La + Lb) / Lt is 36%, Four 54f, 54g, and 54h are provided in one row in the furnace width direction (each 200 mm interval). The ratio of the total length of the exhaust ports 54e, 54f, 54g, 54h in the furnace width direction to the furnace width Lw was 80%.

  The aperture ratio after adjusting the aperture ratio of each exhaust port is 100% at the exhaust ports 54a, 54d, 54e, 54h at both ends, and at the exhaust ports 54b, 54c, 54f, 54g other than both ends. All of the opening ratios were 95%. The ratio of the average exhaust flow velocity at the exhaust ports 54b, 54c, 54f, 54g other than the opposite ends to the average exhaust flow velocity at the exhaust ports 54a, 54d, 54e, 54h on both ends was 1.02 times.

  The connection pipes 56a, 56b, 56c, 56d, 56e, 56f, 56g, and 56h connected to the peripheral edges of the exhaust ports 54a, 54b, 54c, 54d, 54e, 54f, 54g, and 54h each have a height Hs of 150 mm. there were.

  Cross-sectional dimensions and shapes of exhaust gas transfer main ducts 58a connected to the respective upper ends of the connecting cylinders 56a, 56b, 56c, 56d, cross-sectional dimensions and shapes of exhaust gas transfer main ducts 58b connected to the respective upper ends of the 56e, 56f, 56g, and 56h Each of the shapes was a rectangle of 100 mm (length in the furnace length direction) × 3800 mm (length in the furnace width direction).

  In the carbonization furnace 52 having the above-described configuration, the pyrolysis gas flows from the exhaust ports 54a, 54b, 54c, 54d, 54e, 54f, 54g, and 54h to the connecting cylinders 56a, 56b, 56c, 56d, 56e, 56f, 56g, and 56h. And then discharged through the exhaust gas transfer main ducts 58a and 58b to the outside as exhaust gases 60a and 60b.

  In addition, about another structure, the same referential mark as FIG. 1 is attached | subjected to the location similar to FIG. 1, and the description is abbreviate | omitted.

  After 14 days of operation, in the furnace 52, in the connecting cylinders 56a, 56b, 56c, 56d, 56e, 56f, 56g, 56h, and in the exhaust gas transfer main ducts 58a, 58b (particularly near both ends in the furnace width direction) Adhesion of foreign matters such as tar and silica powder was observed, and the product rate was 93%.

Comparative Example 7
Carbon fiber was manufactured using the carbonization furnace 62 shown in FIG. In the carbonization furnace 62, the space in the furnace 62 was a width Lw: 4000 mm, a length Lt: 7000 mm, and a height Hf: 200 mm.

  Rectangular exhaust port of 100 mm (length in the furnace length direction) × 800 mm (length in the furnace width direction) at the position where the length La from the outlet side of the upper wall of the furnace 62 is 500 mm and the length ratio La / Lt is 7% Three 64a, 64b, and 64c were provided in one row in the furnace width direction (each 200 mm interval). The ratio of the total length of the exhaust ports 64a, 64b, 64c in the furnace width direction to the furnace width Lw was 80%.

  A rectangular exhaust port 64d having a length Lb of 2500 mm from the position of this row and a length ratio (La + Lb) / Lt of 36%, which is 100 mm (length in the furnace length direction) × 800 mm (length in the furnace width direction), Three 64e and 64f were provided in one row in the furnace width direction (each 200 mm interval). The ratio of the total length of the exhaust ports 64d, 64e, 64f in the furnace width direction to the furnace width Lw was 80%.

  As for the opening ratio after adjusting the opening ratio of each exhaust port, the opening ratios at the exhaust ports 64a, 64c, 64d, and 64f on both ends are all 100%, and the opening ratios at the exhaust ports 64b and 64e other than the both ends are both Was also 95%. The ratio of the average exhaust flow velocity at the exhaust ports 64b, 64e other than the both ends to the average exhaust flow velocity at the exhaust ports 64a, 64c, 64d, 64f on both ends was 1.00 times.

  The connection pipes 66a, 66b, 66c, 66d, 66e, 66f connected to the peripheral edges of the exhaust ports 64a, 64b, 64c, 64d, 64e, 64f all have a height Hs of 150 mm.

  The cross-sectional size and shape of the exhaust gas transfer main duct 68a connected to the respective upper ends of the connecting cylinders 66a, 66b, and 66c, and the cross-sectional size and shape of the exhaust gas transfer main duct 68b connected to the respective upper ends of 66d, 66e, and 66f are all 100 mm (length in the furnace length direction) × 3800 mm (length in the furnace width direction).

  In the carbonization furnace 62 configured as described above, the pyrolysis gas enters the connection cylinders 66a, 66b, 66c, 66d, 66e, 66f from the exhaust ports 64a, 64b, 64c, 64d, 64e, 64f, and further, an exhaust gas transfer main duct. The exhaust gases 70a and 70b were discharged out of the system through 68a and 68b.

  In addition, about another structure, the same referential mark as FIG. 1 is attached | subjected to the location similar to FIG. 1, and the description is abbreviate | omitted.

  After 14 days of operation, tar, silica powder in the furnace 62, in the connecting cylinders 66a, 66b, 66c, 66d, 66e, 66f, and in the exhaust gas transfer main ducts 68a, 68b (particularly near both ends in the furnace width direction) As a result, the product rate was 90%.

It is the schematic which shows an example of the carbonization furnace of this invention, (A) is the top view, (B) is the side view, (C) is the front view. It is the schematic which shows another example of the carbonization furnace of this invention, (A) is the top view, (B) is the side view, (C) is the front view. It is the schematic which shows another example of the carbonization furnace of this invention, (A) is the top view, (B) is the side view, (C) is the front view. It is the schematic which shows an example of the conventional carbonization furnace, (A) is the top view, (B) is the side view, (C) is the front view. It is the schematic which shows another example of the conventional carbonization furnace, (A) is the top view, (B) is the side view, (C) is the front view. It is the schematic which shows another example of the conventional carbonization furnace, (A) is the top view, (B) is the side view, (C) is the front view. It is the schematic which shows another example of the conventional carbonization furnace, (A) is the top view, (B) is the side view, (C) is the front view. It is the schematic which shows another example of the conventional carbonization furnace, (A) is the top view, (B) is the side view, (C) is the front view. It is the schematic which shows another example of the conventional carbonization furnace, (A) is the top view, (B) is the side view, (C) is the front view.

Explanation of symbols

2, 12, 21, 22, 32, 42, 51, 52, 62 Carbonization furnace 4 Precursor fiber strand 6 Side wall of carbonization furnace 8 Upper wall of carbonization furnace 10a, 10b, 10c, 10d, 13a, 13b, 13c, 24a, 24b, 24c, 24d, 24e, 24f, 24g, 24h, 24i, 24j, 24k, 24l, 34, 44a, 44b, 44c, 54a, 54b, 54c, 54d, 54e, 54f, 54g, 54h, 64a, 64b, 64c, 64d, 64e, 64f Exhaust port 11a, 11b, 11c, 11d, 15a, 15b, 15c, 26a, 26b, 26c, 26d, 26e, 26f, 26g, 26h, 26i, 26j, 26k, 26l 36, 46a, 46b, 46c, 56a, 56b, 56c, 56d, 56e, 56f, 56g, 56h, 66 a, 66b, 66c, 66d, 66e, 66f Connecting cylinders 14, 17, 28a, 28b, 28c, 38, 48a, 48b, 48c, 58a, 58b, 68a, 68b Exhaust gas transfer main ducts 16, 18, 30a, 30b, 30c, 40, 50a, 50b, 50c, 60a, 60b, 70a, 70b Exhaust gas Lt Furnace total length Lw Furnace width Lo, La Length in the furnace length from the furnace outlet to the exhaust outlet Li, Ld From the furnace inlet to the exhaust outlet Length in the furnace length direction Lb, Lc Distance between exhaust ports in the furnace length direction Hf Height of the carbonization furnace Hs Height of the connecting tube

Claims (2)

Three or more exhaust ports are formed in a row in the furnace width direction in a range of 5 to 45% from the outlet with respect to the entire length of the furnace, and the exhaust port includes a flow control valve. Carbonization furnace. The ratio of the average exhaust flow velocity at the exhaust ports other than both ends to the exhaust average flow velocity at the exhaust ports formed at three or more rows in one row in the furnace width direction is 0.90 to 1.10 times. The operation method of the carbonization furnace of a certain one.

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