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 finish heat treatment apparatus for an iron powder. Raw iron powder is placed on a continuous moving hearth and continuously charged into the apparatus. In a pretreatment zone, the raw iron powder is subjected to a pretreatment of heating the raw iron powder in an atmosphere of hydrogen gas and/or inert gas at 450 to 1100° C. In decarburization, deoxidation, and denitrification zones, the pretreated iron powder is subsequently subjected to at least two treatments of decarburization, deoxidation, and denitrification. In the pretreatment zone, a hydrogen gas and/or an inert gas serving as a pretreatment ambient gas is introduced separately from an ambient gas used in the at least two treatments is introduced from the upstream side of the pretreatment zone and released from the downstream side so as to flow in the same direction as a moving direction of the moving hearth.

A method for heat-treating a metal strip, where the metal strip is pre-heated continuously in a pre-heating zone with the aid of hot gas and subsequently undergoes further heat treatment in a directly fired furnace in a reducing and/or oxidizing atmosphere. The metal strip is pre-heated in the pre-heating zone with hot inert gas and further heated with an electric heating system before entering the directly fired furnace. A furnace plant for implementing the process and a related heat recovery system are also disclosed.

A conveying system (1) for conveying a material along a conveying path. The system (1) includes a system housing (3) having a conveying chamber (5), in which the conveying path is arranged, and having at least one secondary chamber (6 to 8), which is connected to the conveying chamber (5) by at least one passage opening and has a fluid atmosphere that is physically and/or chemically different from the fluid atmosphere in the conveying chamber (5). The at least one passage opening (9, 10) and the fluid atmospheres in the conveying chamber (5) and the at least one secondary chamber (6 to 8) set a defined fluid flow in the system housing (3).

Provided is a method for continuously producing a silicon nitride sintered compact for enabling a continuous production of silicon nitride sintered compacts by sintering using a silicon nitride powder having a high β-phase rate. A fired compact 1 housed in a firing jig 2 contains a silicon nitride powder having at least 80% of β-transition rate and 7 to 20 m.sup.2/g of specific surface area together with a sintering additive, where the total content of aluminum element is adjusted not to exceed 800 ppm. The firing jig 2 is supplied into a continuous firing furnace equipped with a closed-type firing container 5 having at its end portions a supplying openable door 3 and a discharging openable door 4 for supplying and discharging the firing jig, a heating mechanism 6 provided on the body periphery of the firing container 5, a conveyance mechanism for supplying/discharging the firing jig into/from the firing container, and a gas-supplying mechanism for supplying an inert gas into the firing container, so that the silicon nitride is heated to a temperature in the range of 1200 to 1800° C. in an inert gas atmosphere and at a pressure of not less than 0 MPa.Math.G and less than 0.1 MPa.Math.G so as to be sintered.

A vertical furnace for the continuous heat treatment of a metal strip, in particular for an electrical steel strip, as seen in the conveying direction of the metal strip, includes an inlet zone for the metal strip; a heating/holding zone with an annealing chamber for heating and holding the metal strip at a certain temperature; a first cooling zone for cooling the metal strip; and a deflection device, arranged downstream of the first cooling zone with at least one roller arrangement, for deflecting the metal strip in the direction of an outlet zone for the metal strip. At least one second cooling zone is arranged downstream of the deflection device with respect to the conveying direction.

A conveying system (1) for conveying a material along a conveying path. The system (1) includes a system housing (3) having a conveying chamber (5), in which the conveying path is arranged, and having at least one secondary chamber (6 to 8), which is connected to the conveying chamber (5) by at least one passage opening and has a fluid atmosphere that is physically and/or chemically different from the fluid atmosphere in the conveying chamber (5). The at least one passage opening (9, 10) and the fluid atmospheres in the conveying chamber (5) and the at least one secondary chamber (6 to 8) set a defined fluid flow in the system housing (3).

A roll-transport device including: a roll that comes into contact with the base material; a support shaft that rotatably supports the roll; and a bearing that is disposed on an outer peripheral surface of the support shaft and has an end surface on one side in an axial direction, which faces an inside of a furnace, and an end surface on the other side in the axial direction, which is positioned on a side of an inner portion (space surrounded by the roll). A purge gas is caused to circulate from the end surface on the other side toward the end surface on the one side of the bearing, and the purge gas is discharged into the furnace from the end surface on the one side of the bearing.

A carrier-type heat-treatment apparatus including a furnace main body that includes heaters and a mesh belt that transports an object to be heat-treated into the furnace main body includes a gas pipe arranged inside the furnace main body, the gas pipe being configured to inject a gas into the furnace main body, in which a low-temperature zone and a high-temperature zone are provided inside the furnace main body with the gas, the low-temperature zone being provided on an entrance side of the furnace main body, the high-temperature zone being provided on an exit side of the furnace main body and having a temperature higher than the low-temperature zone.

A method for heat-treating a metal strip, where the metal strip is pre-heated continuously in a pre-heating zone with the aid of hot gas and subsequently undergoes further heat treatment in a directly fired furnace in a reducing and/or oxidizing atmosphere. The metal strip is pre-heated in the pre-heating zone with hot inert gas and further heated with an electric heating system before entering the directly fired furnace. A furnace plant for implementing the process and a related heat recovery system are also disclosed.