Production method for precarbonized fiber bundle, production method for carbon fiber bundle, and precarbonization furnace

Abstract

An object is to provide a production method for a precarbonized fiber bundle and a precarbonization furnace capable of continuously producing the precarbonized fiber bundle for a long period of time by efficiently discharging a decomposition gas containing a tar component generated when performing a precarbonization treatment at the time of carbon fiber production and retained in a heat treatment chamber throughout the heat treatment chamber. The production method for a precarbonized fiber bundle includes allowing an aligned stabilized fiber bundle vertically arranged in one or two or more tiers to travel horizontally in a heat treatment chamber and heat-treating and precarbonizing the stabilized fiber bundle at a maximum temperature of 300 to 1,000° C. using an inert gas supplied from an inlet side and an outlet side of the heat treatment chamber, in which a flow rate ratio Q2/Q1 satisfies Formula (1) below, where Q1 represents a volume flow rate of gas in a first exhaust discharged out of the heat treatment chamber from a position higher than a position of an uppermost tier of the traveling stabilized fiber bundle, and Q2 represents a volume flow rate of gas in a second exhaust discharged out of the heat treatment chamber from a position lower than the position of the uppermost tier of the traveling stabilized fiber bundle: 0.01≤Q2/Q1≤0.5  Formula (1).

Dependencies are inferred from the claim text.