JP2015028221A - Carbonization furnace, operation method and cleaning method thereof and method of producing carbon fiber using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbonization furnace which allows removal of solid-liquid mixed foreign matters due to a pyrolysis gas discharged in carbonizing flame-resistant fibers even during operation of the carbonization furnace and allows continuous operation of the carbonization furnace, and to provide a method of removing the solid-liquid mixed foreign matters from the carbonization furnace.SOLUTION: A carbonization furnace includes a furnace body formed with an exhaust port, an exhaust gas passage connected to the exhaust port and a collection vessel which is arranged under the exhaust port and has an opening in the upper part. The collection container is attached freely removably to the furnace body through an opening/closing door which blocks the atmosphere between the inside of the furnace body and the inside of the collection container and connects the atmosphere in the furnace body with that in the collection container, which allows free attachment of the collection container to the carbonization furnace and detachment of the collection container from the carbonization furnace even during operation of the carbonization furnace and discharge of solid-liquid mixed foreign matters collected in the collection container out of the furnace body.

Description

  The present invention relates to a carbonization furnace capable of efficiently removing deposits in the furnace, an operation method of the carbonization furnace, and a cleaning method. Furthermore, it is related with the manufacturing method of the carbon fiber which uses this carbonization furnace.

  Carbon fiber composite materials reinforced with carbon fiber made of thermosetting resin or thermoplastic resin have excellent features such as high tensile strength, high tensile modulus, excellent heat resistance and fatigue properties. Widely used in fields such as aviation and space.

  Carbon fiber is fired at 1000 ° C. or higher in an inert gas atmosphere using a carbonization furnace after making raw fiber such as acrylic fiber into flame resistant fiber by heating to 200 to 300 ° C. in air. Manufactured by. In the furnace of 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 pyrolysis gas passes through the exhaust gas path together with the inert gas and is discharged out of the furnace body.

  The pyrolysis gas touches the wall surface of the exhaust gas passage, and part of the pyrolysis gas adheres to the wall surface as a liquid foreign matter 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 as a solid-liquid mixed foreign matter on the wall surface of the exhaust gas passage. When the solid-liquid mixed foreign matter accumulates in the exhaust gas path and the exhaust gas path is closed, the efficiency of discharging the pyrolysis gas to the outside of the furnace body is lowered. As a result, continuous and stable production of carbon fibers becomes difficult. Moreover, when this solid-liquid mixed foreign material falls into the furnace body, the solid-liquid mixed foreign material may accumulate in the furnace body and damage the furnace body. In order to produce carbon fiber continuously and stably, it is important to efficiently discharge the pyrolysis gas generated in the firing step to the outside of the furnace body.

  There is a method of covering the outside of the exhaust gas passage with a heat insulating material or the like and suppressing the precipitation of the solid-liquid mixed foreign matter in the exhaust gas passage. However, in this method, it is necessary to cover the exhaust gas passage with a large amount of heat insulating material. For this reason, it takes enormous time and cost for the decomposition maintenance of the carbonization furnace. In addition, a large amount of waste is generated, which is inappropriate in terms of environment.

  In Patent Document 1, a first exhaust gas passage connected to the furnace body, a second exhaust gas passage connecting the first exhaust gas passage and the combustion chamber, and the second exhaust gas passage are arranged in the second exhaust gas passage. An exhaust gas treatment apparatus for a carbonization furnace, comprising: an exhaust gas flow rate adjustment valve that adjusts the flow rate of exhaust gas (pyrolysis gas) by adjusting the amount of projection into the combustion chamber by moving forward and backward between the passage and the combustion chamber Is disclosed. In this exhaust gas flow rate adjusting valve, a rod-shaped operating rod is extended outside the apparatus. The flow rate of the exhaust gas is adjusted by moving the operating rod forward and backward. The exhaust gas flow rate adjusting valve also has a function of scraping off residues accumulated in the second exhaust gas passage into the combustion chamber. However, in this processing furnace, the residue accumulated in the first exhaust gas passage cannot be removed.

  Patent Document 2 discloses a method for efficiently exhausting pyrolysis gas by arranging a plurality of exhaust ports in a carbonization furnace, further optimizing the speed control of the air volume, the exhaust port diameter, and the like. However, it suppresses the deterioration of exhaust efficiency due to solid-liquid mixed foreign matters such as tar and silica blocking the exhaust gas passage, and damage to the carbonization furnace due to these solid-liquid mixed foreign matters falling and accumulating in the furnace body. It was not possible to achieve stable operation.

JP 2012-67419 A JP 2009-243008 A

  The present invention has been made in view of the above circumstances, and the object of the present invention is to remove solid-liquid mixed foreign matters resulting from pyrolysis gas discharged when carbonizing the flame resistant fiber, from the carbonization furnace. To provide a carbonization furnace that can be removed from a carbonization furnace even during operation, and to enable continuous operation of the carbonization furnace, and to provide a method for removing solid-liquid mixed foreign matters from the carbonization furnace It is.

  The inventor has intensively studied to achieve the above object. As a result, through the open / close door that freely shuts off or connects the atmosphere inside the furnace body of the carbonization furnace and the inside of the collection container, the collection container that collects the solid-liquid mixed foreign matter falling from the exhaust gas path, I came up with the idea of detachably attaching to the furnace body. As a result, it was found that the collection container can be freely attached to and detached from the carbonization furnace even during operation of the carbonization furnace, and the present invention has been completed.

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

[1] a furnace body in which an exhaust port is formed;
An exhaust gas path connected to the exhaust port;
A collection container having an open top installed below the exhaust port;
A carbonization furnace comprising:
A carbonization furnace, wherein the collection container is detachably attached to the furnace body via an open / close door that blocks or connects an atmosphere between the furnace body and the collection container.

  [2] The carbonization furnace according to [1], wherein the exhaust gas passage has a cleaning rod that slides in the exhaust gas passage so as to advance and retreat.

[3] During operation or suspension of the carbonization furnace,
A step of collecting the solid-liquid mixed foreign matter in the exhaust gas passage into a collection container;
A step of blocking the atmosphere inside the furnace body and the inside of the collection container;
Removing the collection container in which the solid-liquid mixed foreign matter has been collected from the carbonization furnace,
The method for cleaning a carbonization furnace according to [1] or [2].

[4] A step of collecting the solid-liquid mixed foreign matter in the exhaust gas passage in a collection container,
A step of blocking the atmosphere inside the furnace body and the inside of the collection container;
Removing the collection container in which the solid-liquid mixed foreign matter has been collected from the carbonization furnace,
A method for operating a carbonization furnace comprising:
The operation method of the carbonization furnace as described in [1] or [2], wherein the solid-liquid mixed foreign matter in the exhaust gas passage is removed during operation of the carbonization furnace.

  [5] A carbon fiber production method using the method for operating a carbonization furnace according to [4].

  In the carbonization furnace of the present invention, since the collection container is installed through an open / close door that shuts off the atmosphere from the inside of the furnace body, the solid-liquid mixed foreign matter dropped into the collection container of the carbonization furnace is removed from the furnace. The inner atmosphere can be removed without substantially changing. Therefore, even during the operation of the carbonization furnace, the solid-liquid mixed foreign matter dropped into the collection container of the carbonization furnace can be removed. Therefore, damage to the carbonization furnace due to accumulation of solid-liquid mixed foreign substances in the furnace for a long period can be suppressed.

  In the carbonization furnace of the present invention, a cleaning rod is provided in the exhaust gas passage. Therefore, it is possible to suppress the exhaust gas passage from being blocked by the accumulation of solid-liquid mixed foreign matter. As a result, the carbonization furnace of the present invention can be operated continuously for a long time.

FIG. 1 is a plan view schematically showing one configuration example of the carbonization furnace of the present invention. FIG. 2 is an end view schematically showing an end surface along the line A1-A2 of FIG. FIG. 3 is an end view schematically showing a state during cleaning of the carbonization furnace of FIG. 1. FIG. 4 is an explanatory view schematically showing another configuration example of the carbonization furnace of the present invention. FIG. 5 is an explanatory view schematically showing a state during cleaning of the carbonization furnace of FIG. 4. FIG. 6 is a plan view schematically showing another configuration example of the carbonization furnace of the present invention. FIG. 7 is an end view schematically showing an end surface along the line A1-A2 of FIG. FIG. 8 is an explanatory view schematically showing another configuration example of the carbonization furnace of the present invention. FIG. 9 is an explanatory view schematically showing another configuration example of the carbonization furnace of the present invention. FIG. 10 is a plan view schematically showing another configuration example of the carbonization furnace of the present invention. FIG. 11 is an end view schematically showing an end surface along the line A1-A2 of FIG. FIG. 12 is an explanatory view schematically showing another configuration example of the carbonization furnace of the present invention.

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

  FIG. 1 is a plan view schematically showing an embodiment of the carbonization furnace of the present invention. FIG. 2 is an explanatory view schematically showing an end surface along the line A1-A2 of FIG.

  In FIGS. 1 and 2, 100 is a carbonization furnace. Reference numeral 11 denotes a tunnel-shaped furnace body, and an exhaust port 13 is formed in the furnace body 11. One end of the first exhaust gas passage 21 is connected to the exhaust port 13 from the outside of the furnace body 11. The first exhaust gas path 21 is connected to intersect with the second exhaust gas path 51 connected to the exhaust gas treatment furnace 55. A cleaning rod 53 is provided in the second exhaust gas passage 51 so as to be able to advance and retreat in the second exhaust gas passage 51.

  A shut-off box 31 is installed below the exhaust port 13. The blocking box 31 has an opening 32 on the upper side, and the opening 32 is provided with an opening / closing door 41 that opens or closes the opening 32 by an opening / closing operation. A collection container 33 having an upper opening is installed in the blocking box 31.

  The collection container 33 can be taken out from a side door 34 formed on the side surface of the furnace body 11. That is, the collection container 33 is detachably installed from the side surface side of the furnace body 11. FIG. 3 shows a state where the open / close door 41 is closed and the collection container 33 is taken out from the side door 34 in the carbonization furnace of FIG. When the opening / closing door 41 is closed, the opening 32 is closed, and the atmosphere in the furnace body 11 and the atmosphere in the blocking box 31 are blocked. When the opening / closing door 41 is opened, the opening 32 is opened, and the atmosphere in the furnace body 11 and the atmosphere in the blocking box 31 are connected.

  Next, the use mode of the carbonization furnace 100 will be described.

  Inside the tunnel-shaped furnace body 11 of the carbonization furnace, a fiber yarn 70 made of flame-resistant fibers is carbonized while traveling in the direction of the arrow in FIG. 1 in an inert atmosphere. During the carbonization, the pyrolysis gas generated in the furnace body 11 is sent to the exhaust gas treatment furnace 55 side through the first exhaust gas passage 21 connected to the exhaust port 13. Due to the passage of the pyrolysis gas or the like, solid-liquid mixed foreign matter formed by mixing tar, silica, or the like is deposited on the inner wall surface of the first exhaust gas passage 21. When the solid-liquid mixed foreign matter falls off from the first exhaust gas passage 21, the solid-liquid mixed foreign matter falls into the furnace body 11 through the exhaust port 13.

  During normal operation, the opening 32 of the blocking box 31 is opened. Therefore, the solid-liquid mixed foreign matter dropped into the furnace body 11 is collected in the collection container 33 through the opening 32 of the blocking box 31 installed below the exhaust port 13 (FIG. 2).

  When the collection container 33 is taken out of the carbonization furnace 100, the open / close door 41 is closed, and the opening 32 of the blocking box 31 is closed. Thereby, the atmosphere between the furnace body 11 and the shut-off box 31 is shut off. Thereafter, the collection container 33 in the blocking box 31 is taken out from the side door 34 formed on the side surface of the furnace body 11 (FIG. 3). Thereby, the solid-liquid mixed foreign material dropped into the furnace body 11 is taken out of the furnace body from the furnace body. At this time, since the inert atmosphere in the furnace body 11 is blocked from the shut-off box 31 side by the open / close door 41, the inert atmosphere in the furnace body 11 does not substantially change even when the side door 34 is opened. . Therefore, even during the operation of the carbonization furnace 100, the operation can be continued while removing the residue in the carbonization furnace 100.

  FIG. 4 is an explanatory view schematically showing the structure of a carbonization furnace in which a part of the structure of the carbonization furnace of FIG. 1 is different. About the same structure as FIGS. 1-3, the same referential mark is attached | subjected and the description is abbreviate | omitted. In FIG. 4, an opening 12 is formed in the furnace body 15 below the exhaust port 13. The opening 12 is provided with an opening / closing door 41 that opens or closes the opening 12 by an opening / closing operation. Immediately below the opening 12 of the furnace body 15, a collection container 35 having an open top is detachably and airtightly connected to the furnace body 15 by means (not shown).

  During normal operation, the opening 12 of the furnace body 15 is open. Therefore, the solid-liquid mixed foreign matter falling into the furnace body 15 is collected in the collection container 35 through the opening 12 formed below the exhaust port 13 (FIG. 4).

  When the collection container 35 is taken out of the carbonization furnace, the open / close door 41 is closed and the opening 12 of the furnace body 15 is closed. Thereby, the atmosphere between the furnace body 15 and the collection container 35 is shut off. Then, the collection container 35 is taken out from the furnace body 15 (FIG. 5).

  FIG. 6 is a plan view schematically showing another configuration example of the carbonization furnace of the present invention. FIG. 7 is an explanatory view schematically showing an end surface along the line A1-A2 of FIG. About the same structure as FIGS. 1-3, the same referential mark is attached | subjected and the description is abbreviate | omitted.

  A cleaning rod 23 is provided in the first exhaust gas passage 21 of the carbonization furnace 200 of FIG. 6 so as to be able to advance and retreat in the first exhaust gas passage 21. By moving the cleaning rod 23 forward and backward from the outside in the first exhaust gas passage 21, it is possible to drop the solid-liquid mixed foreign matter deposited and adhered in the first exhaust gas passage 21 into the furnace body 11. . Thereby, the blockage | exhaustion of the exhaust gas path by a solid-liquid mixed foreign material depositing in the 1st exhaust gas path 21 can be suppressed effectively.

  1 to 7, the exhaust port 13 is formed so as to protrude into the furnace body. However, the present invention is not limited thereto, and may be formed without protruding as illustrated in FIG. 8.

  FIG. 9 is an explanatory view schematically showing another configuration example of the carbonization furnace of the present invention. About the same structure as FIGS. 1-8, the same referential mark is attached | subjected and the description is abbreviate | omitted. In the carbonization furnace 300 of FIG. 9, the traveling direction of the fiber yarn 70 in the furnace body 16 is a direction perpendicular to the paper surface.

  The first exhaust gas passage 24 of the carbonization furnace 300 in FIG. 9 is attached to be inclined. Thereby, the solid-liquid mixed foreign matter generated in the first exhaust gas passage 24 is easily dropped into the furnace body 16.

  The second exhaust gas path 63 connected to the first exhaust gas path 24 is connected to the third exhaust gas path 65. A plurality of second exhaust gas passages 63 are connected to the third exhaust gas passage 65 (two in FIG. 9), and the pyrolysis gas sent from these is sent to the exhaust gas treatment furnace 55.

  The carbonization furnace 300 of FIG. 9 has a plurality of (two in FIG. 9) exhaust ports and collection containers installed in the furnace body 16. Therefore, the carbonization furnace 300 has high exhaust gas exhaust efficiency.

  FIG. 10 is a plan view schematically showing another configuration example of the carbonization furnace of the present invention. FIG. 11 is an end view schematically showing an end surface along the line A1-A2 of FIG. About the same structure as FIGS. 1-9, the same referential mark is attached | subjected and the description is abbreviate | omitted.

  In the carbonization furnace 400 of FIG. 11, the exhaust port 13 is formed in the center of the upper wall of the furnace body 18, and the shut-off box 31, the collection container 33, and the open / close door 41 are arranged in the upper part of the furnace body 18. ing. A cleaning rod 23 is provided in the first exhaust gas passage 21 of the carbonization furnace 400 so as to be able to advance and retreat in the first exhaust gas passage 21. By moving the cleaning rod 23 forward and backward from the outside in the first exhaust gas passage 21, it is possible to drop the solid-liquid mixed foreign matter deposited and adhered in the first exhaust gas passage 21 into the furnace body 18. . Thereby, the blockage | exhaustion of the exhaust gas path by a solid-liquid mixed foreign material depositing in the 1st exhaust gas path 21 can be suppressed effectively.

  FIG. 12 is an explanatory view schematically showing another configuration example of the carbonization furnace of the present invention. The carbonization furnace 500 of FIG. 12 has a plurality (two in FIG. 12) of exhaust ports 13 formed on the upper wall of the furnace body 19. Further, below each exhaust port, a shut-off box 31, a collection container 33, and an open / close door 41 are respectively installed in the upper part of the furnace body 19. The carbonization furnace 500 has high exhaust gas exhaust efficiency.

  The number of exhaust ports and collection containers installed is appropriately changed depending on the size of the furnace body, but 2 to 3 are preferable. The exhaust port may be formed at any position on the furnace body. However, considering the exhaust efficiency of pyrolysis gas and the ease of device design, it is preferably formed on the upper wall of the furnace body. It is particularly preferable to form the portion.

  The length of each barrier box in the furnace length direction is preferably 0.1 to 0.2 times the furnace length. Moreover, it is preferable that the length of the collection container 33 in the furnace length direction is 0.06 to 0.18 times the furnace length.

  When the size of the shielding box is larger than 0.2 times the furnace length, the opening becomes too large, and the outside air easily enters the furnace. Therefore, it becomes difficult to remove the collection container while maintaining the temperature in the furnace. On the other hand, when the length is less than 0.1 times the furnace length, the collection container is filled up with the residue, so the collection container must be frequently taken out. For this reason, the operation efficiency is poor, which is not preferable.

  1, 6, 7, and 9-12, the cleaning rod may have any shape as long as it can remove all or part of the solid-liquid mixed foreign matter accumulated in the exhaust gas passage. In order to efficiently remove the solid-liquid mixed foreign matter in the exhaust gas passage, a member having an outer diameter substantially the same as the inner diameter of the exhaust gas passage is provided at the tip of the cleaning rod, and is formed to be slidable with the exhaust gas passage. Preferably it is.

  The carbon fiber produced using the carbonization furnace of the present invention is not particularly limited. It can be used for the production of any carbon fiber such as pitch, rayon, and acrylonitrile (PAN). In view of operability, process passability, mechanical strength, and the like, a PAN-based carbon fiber bundle is preferable.

Example 1
Carbon fiber was manufactured using the carbonization furnace 300 shown in FIG. In this carbonization furnace 300, the space in the furnace body 16 was a furnace width Lw: 4000 mm, a furnace length Lt: 7000 mm, and a height Hf: 250 mm. In the furnace body 16, a circular exhaust port 13 having a diameter of 100 mm centered at a position where the distance Lo from the outlet side is 2500 mm and the distance Li from the inlet side is 4500 mm (length ratio Lo / Lt is 36%) is 2 Provided in the place. A blocking box 31 having a width of 1050 mm and a collecting container 33 having a width of 900 mm were respectively installed below the exhaust port 13. The exhaust gas path 24 connected to each exhaust port 13 had a cylindrical shape with a diameter of 100 mm.

  In the carbonization furnace 300 having this configuration, the pyrolysis gas enters the first exhaust gas path 24 from the exhaust port 13, and further passes through the second exhaust gas path 63 and the third exhaust gas furnace 65 and is discharged to the exhaust gas treatment furnace 55. The pyrolysis gas was burned in the gas processing furnace 55 and rendered harmless, and then released to the outside of the system.

  The cleaning rods 23, 61, and 67 were moved forward and backward at a frequency of once / day, and the solid-liquid mixed foreign matter in each exhaust gas furnace was collected in the collection container 33. On the 15th day from the start of operation, the open / close door 41 was closed to shut off the atmosphere in the furnace body 16 and the atmosphere in the shielding box 31, and then the collection container 33 was taken out. After removing the solid-liquid mixed foreign matter in the collection container 33, the repair container 33 and the open / close door 41 were returned to the original in the reverse order. During this time, the operation of the carbonization furnace 300 was continued. This was defined as one cycle and repeated four cycles (that is, continuous operation for 60 days), and then rested. As a result, almost no foreign matter such as tar and silica powder was found in the furnace body 16 and the exhaust gas passages 24, 63 and 65, and the yield was 95%.

(Comparative Example 1)
As a comparative example, carbonization having the same structure as in Example 1 except that the collection container 33 is not installed in the furnace body 16 and the cleaning rods 23 and 61 are not provided in the first and second exhaust gas paths. Carbon fiber was produced using a furnace. As a result, the solid-liquid mixed foreign matter adheres to the carbonization furnace and the exhaust gas passage, in particular, the tube walls in the first and second exhaust gas passages. did. The yield was 90%.

100, 200, 300, 400, 500: Carbonization furnace 11, 15, 16, 17, 18, 19: Furnace body 12: Opening part of furnace body 13: Exhaust port 21, 24: First exhaust gas path 23, 53, 61, 67: Cleaning rod 31: Shut-off box 32: Opening part of the shut-off box 33, 35: Collection container 34: Side door 41: Opening / closing door 51, 63: Second exhaust gas passage 55: Exhaust gas treatment furnace 65: Third exhaust gas Road 70: Textile yarn

Claims (5)

A furnace body in which an exhaust port is formed;
An exhaust gas path connected to the exhaust port;
A collection container having an open top installed below the exhaust port;
A carbonization furnace comprising:
A carbonization furnace, wherein the collection container is detachably attached to the furnace body via an open / close door that blocks or connects an atmosphere between the furnace body and the collection container.   The carbonization furnace of Claim 1 which has the cleaning rod which slides in the said exhaust gas path so that advancing and retreating is possible. During operation or outage of the carbonization furnace,
A step of collecting the solid-liquid mixed foreign matter in the exhaust gas passage into a collection container;
A step of blocking the atmosphere inside the furnace body and the inside of the collection container;
Removing the collection container in which the solid-liquid mixed foreign matter has been collected from the carbonization furnace,
The cleaning method of the carbonization furnace of Claim 1 or 2 which has these. A step of collecting the solid-liquid mixed foreign matter in the exhaust gas passage into a collection container;
A step of blocking the atmosphere inside the furnace body and the inside of the collection container;
Removing the collection container in which the solid-liquid mixed foreign matter has been collected from the carbonization furnace,
A method for operating a carbonization furnace comprising:
The operation method of a carbonization furnace according to claim 1 or 2, wherein solid-liquid mixed foreign matters in the exhaust gas passage are removed during operation of the carbonization furnace.   The manufacturing method of the carbon fiber using the operating method of the carbonization furnace of Claim 4.

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