The present invention provides an exhaust gas treatment method and an exhaust gas treatment device which prevent the generation of NO.sub.X, and treat a first exhaust gas and a second exhaust gas with a small amount of fuel, and the exhaust gas treatment method comprises a first combustion step which treats a first exhaust gas discharged from a carbonization furnace for carbonizing a fibrous substance in an inert atmosphere and a graphitization furnace for graphitizing a fibrous substance in an inert atmosphere and a second combustion step of treating a second exhaust gas discharged from a flameproofing furnace for flameproofing a fibrous substance in air atmosphere, wherein the first exhaust gas is combusted at an oxygen ratio of 0.8 or less in the first combustion step, and the second exhaust gas is combusted in the second combustion step using sensible heat and latent heat of a third exhaust gas discharged in the first combustion step.

A method for manufacturing a carbon fiber bundle includes a stabilization process of subjecting an acrylic fiber bundle to a heat treatment within a range of 200° C. to 300° C. in an oxidizing atmosphere; a pre-carbonization process of performing a heat treatment within a range of 300° C. to 1,000° C. using a heat treatment furnace having at least one inert gas supply port on each of an incoming side and an outgoing side of the fiber bundle and at least one exhaust port between the incoming-side and outgoing-side inert gas supply ports, the heat treatment being performed with a temperature of an inert gas supplied being higher on the outgoing side than on the incoming side; and a carbonization process of performing a heat treatment at a temperature of 1,000° C. to 2,000° C. in an inert gas atmosphere, in which from a position at which an atmospheric temperature in the heat treatment furnace is 300° C., the position being closest to the outgoing side in a machine length direction, up to the inert gas supply port on the incoming side, a flow of an inert atmosphere within the heat treatment furnace in the pre-carbonization process consists only of a flow in a parallel flow direction with respect to a travel direction of the fiber bundle in the machine length direction. Provided is a method for manufacturing a carbon fiber bundle by which manufacturing can be performed continuously for a long time by preventing entry into a temperature zone causing deposition of a gasified decomposition product, such as tar, that is generated at the time of the pre-carbonization treatment in manufacturing of carbon fibers and that stays within the heat treatment furnace.

A method for manufacturing a carbon fiber bundle includes a stabilization process of subjecting an acrylic fiber bundle to a heat treatment within a range of 200° C. to 300° C. in an oxidizing atmosphere; a pre-carbonization process of performing a heat treatment within a range of 300° C. to 1,000° C. using a heat treatment furnace having at least one inert gas supply port on each of an incoming side and an outgoing side of the fiber bundle and at least one exhaust port between the incoming-side and outgoing-side inert gas supply ports, the heat treatment being performed with a temperature of an inert gas supplied being higher on the outgoing side than on the incoming side; and a carbonization process of performing a heat treatment at a temperature of 1,000° C. to 2,000° C. in an inert gas atmosphere, in which from a position at which an atmospheric temperature in the heat treatment furnace is 300° C., the position being closest to the outgoing side in a machine length direction, up to the inert gas supply port on the incoming side, a flow of an inert atmosphere within the heat treatment furnace in the pre-carbonization process consists only of a flow in a parallel flow direction with respect to a travel direction of the fiber bundle in the machine length direction. Provided is a method for manufacturing a carbon fiber bundle by which manufacturing can be performed continuously for a long time by preventing entry into a temperature zone causing deposition of a gasified decomposition product, such as tar, that is generated at the time of the pre-carbonization treatment in manufacturing of carbon fibers and that stays within the heat treatment furnace.

To perform a flame-resistant treatment on a precursor fiber strand by sending hot air to a heat treatment chamber (2) through a hot air blowing nozzle (4) in a direction parallel to a running direction of a precursor fiber strand (10). The hot air blowing from the hot air blowing nozzle (4) passes through a porous plate and a rectifying member that satisfy the following conditions (1) to (4), wherein the conditions are set as follows: (1) A/B≧4.0; (2) 0.15≦α≦0.35; (3) 0≦B−d≦20; and (4) 80% or more of an area of one opening of the porous plate when causing facing surfaces of the porous plate and the rectifying member to overlap each other is included in one opening of the rectifying member, A indicating a hot air passage distance (mm) of the rectifying member, B indicating a horizontal maximum distance (mm) of one opening of the rectifying member, α indicating a rate of hole area of the porous plate, and d indicating an equivalent diameter (mm) of the porous plate. Accordingly, it is possible to provide a parallel stream type flame-resistant heat treatment furnace having exhibiting the uniform heat transfer performance throughout the inside of the heat treatment chamber by preventing the blockage of the nozzle caused by a silicone compound generated inside the heat treatment chamber even in the hot air blowing nozzle having a simple structure.

To perform a flame-resistant treatment on a precursor fiber strand by sending hot air to a heat treatment chamber (2) through a hot air blowing nozzle (4) in a direction parallel to a running direction of a precursor fiber strand (10). The hot air blowing from the hot air blowing nozzle (4) passes through a porous plate and a rectifying member that satisfy the following conditions (1) to (4), wherein the conditions are set as follows: (1) A/B≧4.0; (2) 0.15≦α≦0.35; (3) 0≦B−d≦20; and (4) 80% or more of an area of one opening of the porous plate when causing facing surfaces of the porous plate and the rectifying member to overlap each other is included in one opening of the rectifying member, A indicating a hot air passage distance (mm) of the rectifying member, B indicating a horizontal maximum distance (mm) of one opening of the rectifying member, α indicating a rate of hole area of the porous plate, and d indicating an equivalent diameter (mm) of the porous plate. Accordingly, it is possible to provide a parallel stream type flame-resistant heat treatment furnace having exhibiting the uniform heat transfer performance throughout the inside of the heat treatment chamber by preventing the blockage of the nozzle caused by a silicone compound generated inside the heat treatment chamber even in the hot air blowing nozzle having a simple structure.

A carbon fiber production method includes a carbon fiber production step including an oxidation step and a carbonization step; and an exhaust gas processing step including a heat exchange step; an external air mixing step; and a mixed external air supplying step in which the mixed external air is supplied to at least one step that uses heated gas in the steps in the carbon fiber production step; and among the exhaust gases, a high heating value exhaust gas having a heating value of 250 kcal/Nm.sup.3 or higher is supplied to an inlet side of an exhaust gas combustion apparatus and a low heating value exhaust gas having a heating value lower than 150 kcal/Nm.sup.3 is supplied to an outlet side of the exhaust gas combustion apparatus, respectively.

A carbon fiber production method includes a carbon fiber production step including an oxidation step and a carbonization step; and an exhaust gas processing step including a heat exchange step; an external air mixing step; and a mixed external air supplying step in which the mixed external air is supplied to at least one step that uses heated gas in the steps in the carbon fiber production step; and among the exhaust gases, a high heating value exhaust gas having a heating value of 250 kcal/Nm.sup.3 or higher is supplied to an inlet side of an exhaust gas combustion apparatus and a low heating value exhaust gas having a heating value lower than 150 kcal/Nm.sup.3 is supplied to an outlet side of the exhaust gas combustion apparatus, respectively.

The invention relates to an apparatus for passing at least one fiber tow multiple times through an oxidation furnace by means of godets, the at least one fiber tow being diverted via at least one godet that is arranged offset. According to the invention, the godet comprises a shaft on which at least two single rollers are arranged to be mounted, each single roller being arranged so as to be rotatable on the shaft.

The invention relates to an apparatus for passing at least one fiber tow multiple times through an oxidation furnace by means of godets, the at least one fiber tow being diverted via at least one godet that is arranged offset. According to the invention, the godet comprises a shaft on which at least two single rollers are arranged to be mounted, each single roller being arranged so as to be rotatable on the shaft.

The problem of the present invention is to provide a carbon fiber manufacturing device in which fiber to be carbonized is irradiated with microwaves and thereby heated, wherein the carbon fiber manufacturing device is compact and capable of performing carbonization at atmospheric pressure without requiring an electromagnetic wave absorber or other additives or preliminary carbonization through external heating. This carbon fiber manufacturing device (200) includes: a cylindrical furnace (27) comprising a cylindrical waveguide in which one end is closed, a fiber outlet (27b) being formed in the one end of the cylindrical waveguide and a fiber inlet (27a) being formed in the other end of the cylindrical waveguide; a microwave oscillator (21) for introducing microwaves into the cylindrical furnace (27); and a connection waveguide (22) having one end connected to the microwave oscillator (21) side and the other end connected to one end of the cylindrical furnace (27).