JP4657113B2 - Exhaust gas collection box - Google Patents

Description

  The present invention relates to an exhaust gas collection box formed in the upper part of a carbonization furnace. More specifically, the present invention relates to an exhaust gas collection box that efficiently transfers exhaust gas generated in a carbonization furnace to an external exhaust gas treatment device or the like and discharges it outside the system.

  In the method of producing carbon fiber by firing raw material fibers such as polyacrylonitrile (PAN), pitch, phenol, cellulose, rayon, etc. as precursor fibers, the raw material fibers are usually first in the apparatus in an oxidizing atmosphere. Flame-resistant fiber (oxidized fiber) is obtained by applying a flame-proofing treatment with a heat treatment apparatus having a temperature of 300 ° C. or lower. In this flameproofing treatment, the raw fibers are usually bundled and fed into a heat treatment apparatus as a slightly twisted yarn (strand). Next, carbonization is performed by heat treatment in a carbonization furnace at 400 ° C. or higher.

  In the carbonization process, exhaust gas is generated. Usually, 10 to 40% by mass of the running strand is gasified. This gas passes through the discharge port and is discharged out of the carbonization furnace (see, for example, Patent Document 1).

  The carbonization furnace is roughly divided into a horizontal carbonization furnace that supplies the oxidized fibers in the carbonization furnace along the horizontal direction, and an oxidation fiber in the carbonization furnace from the top to the bottom, that is, along the vertical direction. There is a vertical carbonization furnace to supply.

The horizontal carbonization furnace requires a means for supporting the oxidized fibers traveling in the furnace, so that the carbonization furnace becomes larger and the entire furnace becomes more complicated. On the other hand, since the vertical carbonization furnace does not particularly require a means for supporting the oxidized fibers traveling in the core tube, it is possible to avoid complication and enlargement of the entire furnace.
JP-A-62-85029 (Claims)

  The present inventor newly manufactures a vertical carbonization furnace characterized by the structure of the exhaust gas collection box attached to the upper part of the furnace shown in the schematic perspective view of FIG. 5, and manufactures carbon fiber using this carbonization furnace. Tried.

  In FIG. 5, 32 is a carbonization furnace facility including peripheral facilities, and is composed of an upper exhaust gas collection box 34 and a lower carbonization furnace body 36. The exhaust gas collection box 34 is a box for collecting the exhaust gas generated in the carbonization furnace main body 36 so that it does not diffuse around.

  Reference numeral 38 denotes an oxidized fiber strand. The oxidized fiber strands are arranged in parallel with each other and are carried into the exhaust gas collection box 34 from the oxidized fiber strand group carrying slit 40 formed on the upper wall of the exhaust gas collection box 34.

  Next, the oxidized fiber 38 travels from the upper side to the lower side in the exhaust gas collection box 34, and then travels from the upper side to the lower side in the core tube in the carbonization furnace body 36, and is carbonized to produce carbon fibers.

  Three circular openings (not shown) are formed in the back wall 42a of the two walls 42a and 42b of the exhaust gas collection box 34. Connection pipes 44a, 44b, and 44c are connected to the periphery of the opening.

  All of these connection pipes 44 a, 44 b, 44 c are bent downward at a predetermined length, and their lower ends are connected to the exhaust gas transfer main duct 46.

  In the carbonization furnace main body 36 and the exhaust gas collection box 34, the exhaust gas proceeds toward the opening formed in the back wall 42a, enters the connection pipes 44a, 44b, and 44c having a circular cross section through the opening, and further transfers the exhaust gas. It is discharged out of the system through the main duct 46.

  However, since a considerable amount of exhaust gas moves in the exhaust gas collection box 34 through a complicated flow path, there is a problem that it cannot be smoothly extracted from the exhaust gas collection box 34 and stays in the exhaust gas collection box 34.

  When the exhaust gas containing tar stays, the tar tends to adhere to the inner wall of the exhaust gas collection box 34. Therefore, there is a risk that the opening, the connection pipe and the like may be blocked unless the work doors 48a and 48b provided on the front wall 42b are frequently opened to clean the inside. Further, due to the adhesion of the tar on the inner wall, there is a risk that the tar contaminates the oxidized fiber strand and reduces the productivity of the carbon fiber.

  While various studies have been made by the present inventor to solve the above problems, a duct connecting the exhaust gas collection box and the exhaust gas transfer main duct is arranged on the upper part of the exhaust gas collection box toward the back side of the exhaust gas collection box. Thus, it has been found that the exhaust gas can be smoothly extracted from the exhaust gas collection box by forming it wider obliquely upward, and the present invention has been completed.

  Accordingly, an object of the present invention is to provide an exhaust gas collection box that solves the above problems.

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

  [1] An exhaust gas collection box formed on an upper part of a carbonization furnace for producing carbon fibers by firing a group of oxidized fiber strands running in the carbonization furnace from above to below in parallel with each other, The upper wall has an oxidized fiber strand group carry-in slit, the lower wall has an oxidized fiber strand group carry-out slit, and is wide on the upper side of the exhaust gas collection box and in the vicinity of the back wall. Exhaust gas collection box with exhaust gas duct.

  [2] The exhaust gas collection box according to [1], wherein an opening / closing door is formed on a front wall parallel to the running surface formed by the oxidized fiber strand group.

  Since the exhaust gas collection box of the present invention is configured as described above, exhaust gas can be smoothly extracted from the exhaust gas collection box.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic perspective view showing an example of an exhaust gas collection box and its peripheral equipment according to the present invention. FIG. 2 is a schematic view of the exhaust gas collection box of FIG. 1, (A) is a side view thereof, and (B) is a plan view thereof.

  1 and 2, reference numeral 2 denotes a carbonization furnace equipment including peripheral equipment, which is composed of an upper exhaust gas collection box 4 and a lower carbonization furnace body 6. The exhaust gas collection box 4 collects the exhaust gas generated in the carbonization furnace main body 6 so that it does not diffuse around. Reference numeral 8 denotes oxidized fiber strands, and the strands are arranged in parallel with each other and are carried into the interior through the oxidized fiber strand group loading slit 10 on the upper surface of the exhaust gas collection box 4.

  Next, the oxidized fiber 8 travels from the upper side to the lower side in the exhaust gas collection box 4, and then enters the upper part of the carbonization furnace main body 6 from the oxidized fiber strand group discharge slit (not shown) formed on the lower wall of the exhaust gas collection box 4. The carbon fiber is supplied and travels in a core tube (not shown) in the carbonization furnace main body 6 from the upper side to the lower side. At this time, carbonization is performed to produce carbon fibers.

  An exhaust gas duct 14 protruding obliquely upward toward the back surface direction of the box 4 is formed at the upper part of the exhaust gas collection box 4.

  The exhaust gas duct 14 has a so-called funnel shape with a hollow pyramid shape in which an opening area formed in a rectangle gradually decreases from the bottom to the top. The long side q of the lower opening end of the exhaust gas duct 14 is formed substantially equal to the length Q in the width direction of the exhaust gas collection box 4 as shown in FIG. Here, the width direction of the box 4 is defined by the length direction of the oxidized fiber strand group loading slit 10. The short side s of the lower opening end of the exhaust gas duct 14 is formed to be approximately ½ of the depth length P of the exhaust gas collection box 4 as shown in FIG. p is a horizontal length component of the short side s.

  The upper end side of the exhaust gas duct 14 is connected to a connection duct 16, and the connection duct 16 is further connected to the exhaust gas transfer main duct 12. Thus, the exhaust gas collection box 4 and the exhaust gas transfer main duct 12 are communicated with each other.

  Opening and closing doors 22a and 22b are formed on the front wall 20b of the two walls 20a and 20b parallel to the running surface of the exhaust gas collection box 4 where the oxidized fiber strand groups 8 are arranged in parallel to each other.

  The inclination angle of the exhaust gas duct 14 obliquely upward is preferably 20 to 75 ° on the upper surface of the exhaust gas duct 14 and 30 to 80 ° on the lower surface of the exhaust gas duct 14 with respect to the horizontal plane.

  The attachment position of the exhaust gas duct 14 with respect to the exhaust gas collection box 4 is the upper side of the exhaust gas collection box 4. That is, as shown in FIG. 2A, the exhaust gas duct 14 may be attached across the upper wall 18 and the back wall 20a of the exhaust gas collection box 4.

  Or you may attach to the back wall 20a side of the upper wall 18 of the exhaust gas collection box 4 as shown in FIG. Furthermore, you may attach to the upper part side of the back wall 20a of the exhaust gas collection box 4 as shown in FIG.

  The attachment width p (distance from the back wall 20a) of the exhaust gas duct 14 to the upper wall 18 is preferably 90% or less, more preferably 80% or less of the depth P of the exhaust gas collection box 4.

  The attachment width r (distance from the upper wall 18) of the exhaust gas duct 14 to the back wall 20a is preferably 80% or less, more preferably 60% or less of the height R of the exhaust gas collection box 4.

  As shown in FIGS. 1 and 2, when the exhaust gas duct 14 is mounted across the upper wall 18 and the back wall 20a of the exhaust gas collection box 4, the mounting width is the same.

  Hereinafter, the operation of the exhaust gas duct 14 will be described. Exhaust gas generated from the oxidized fiber 8 in the exhaust gas collection box 4 smoothly proceeds toward the back of the upper surface, enters the exhaust gas duct 14, and is further discharged out of the system through the exhaust gas transfer main duct 12.

  Since the exhaust gas can be smoothly extracted from the exhaust gas collection box 4, the retention of the exhaust gas in the exhaust gas collection box 4 is reduced. Thereby, the adhesion of tar on the inner wall of the exhaust gas collection box 4 is reduced. Therefore, the risk of closing the exhaust gas flow path such as the exhaust gas duct is reduced, the frequency of opening and cleaning the work doors 22a and 22b provided on the front wall 20b is reduced, and the workability is improved. In addition, the reduction of the adhesion of the tar on the inner wall reduces the risk that the tar contaminates the oxidized fiber strand, and increases the productivity of the carbon fiber.

  Since the exhaust gas flow path in the exhaust gas collection box 4 is simple and the structure allows the exhaust gas to escape smoothly, there is no need to expand the exhaust gas collection box 4 in the direction of the back wall 20a and the direction of the front wall 20b. Therefore, the exhaust gas collection box 4 can be kept small, and the complication and enlargement of the equipment can be avoided.

  1 and 2, the upper end long side l of the exhaust gas duct 14 is shorter than the lower end long side m, but may be the same length.

  Further, the connection duct 16 has a rectangular cross-sectional shape, but the cross-sectional shape is arbitrary, for example, a diamond shape or an elliptical shape can be used. Furthermore, the form of the exhaust gas duct of the present invention is not limited to the form of FIGS. 1 to 4 and may be appropriately modified unless the gist of the present invention is changed.

Example 1
Carbon fiber was manufactured using the carbonization furnace which has the exhaust gas duct shown in FIG.

  The exhaust gas collection box 4 has a length (distance between the back wall 20a and the front wall 20b) of 1.0 m, a width (width of the back wall 20a or the front wall 20b) of 2.5 m, and a height of 1.0 m. there were. The length of the connection duct 16 in the exhaust gas flow path direction was 0.7 m. The inclination angle of the exhaust gas duct 14 obliquely upward was 60 ° on the upper surface of the exhaust gas duct 14 and 70 ° on the lower surface of the exhaust gas duct 14 with respect to the horizontal plane. The diameter of the exhaust gas transfer main duct 12 was 0.25 m.

  When carbon fibers were produced by passing oxidized fibers through the carbonization furnace, the exhaust gas was smoothly extracted from the exhaust gas collection box 4 and tar adhesion on the inner wall of the exhaust gas collection box 4 was reduced. Therefore, tar contamination of oxidized fiber strands is reduced, and the product collection rate (yield of products free from yarn breakage due to process trouble and tar adhesion) is 92% of the theoretical value, and heat treatment is performed with high productivity. I was able to.

Comparative Example 1
Carbon fiber was produced using a carbonization furnace having an exhaust gas duct and its peripheral equipment shown in FIG.

  The exhaust gas collection box 34 has a vertical (distance between the back wall 20a and the front wall 20b) of 2.0 m, a horizontal (width of the back wall 42a or the front wall 42b) of 2.5 m, and a height of 1.0 m. there were. The connection pipes 44a, 44b and 44c had diameters of 0.1 m, 0.15 m and 0.1 m, respectively. The diameter of the exhaust gas transfer main duct 46 was 0.25 m.

  When carbon fibers were produced by passing oxidized fibers through the carbonization furnace, the exhaust gas was not smoothly extracted from the exhaust gas collection box 4, and tar adhered to the inner wall of the exhaust gas collection box 34. For this reason, the product collection rate was 80% of the theoretical value due to the influence of contamination of oxidized fiber strands by tar, and the productivity was low.

It is a schematic perspective view which shows an example of the exhaust gas collection box of this invention, and its peripheral equipment. It is the schematic which shows an example of the exhaust gas collection box of this invention, and its peripheral equipment, (A) is the side view, (B) is the top view. It is a schematic side view which shows the other example of the waste gas collection box of this invention, and its peripheral equipment. It is a schematic side view which shows the further another example of the waste gas collection box of this invention, and its peripheral equipment. It is a schematic perspective view which shows the exhaust gas collection box used in the comparative example 1, and its peripheral equipment.

Explanation of symbols

2, 32 Carbonization furnace equipment including peripheral equipment 4, 34 Exhaust gas collection box 6, 36 Carbonization furnace main body 8, 38 Oxidized fiber strand 10, 40 Oxidized fiber strand group loading slit 12, 46 Exhaust gas transfer main duct 14 Exhaust gas duct 16 Connection duct 18 Upper wall of exhaust gas collection box 20a, 42a Back wall of exhaust gas collection box 20b, 42b Front wall of exhaust gas collection box 22a, 22b, 48a, 48b Working door 44a, 44b, 44c Connection pipe

Claims (2)

An exhaust gas collection box formed at the upper part of a carbonization furnace for producing carbon fibers by firing a group of oxidized fiber strands running in the carbonization furnace from the top to the bottom in parallel with each other. A wide exhaust gas duct having an oxidized fiber strand group carrying-in slit, an oxidized fiber strand group carrying-out slit on the lower wall, and protruding toward the upper rear side of the exhaust gas collection box on the upper side of the exhaust gas collection box and in the vicinity of the back wall With exhaust gas collection box. The exhaust gas collection box according to claim 1, wherein an opening / closing door is formed on a front wall parallel to the running surface formed by the oxidized fiber strand group.

Images