35-50K carbon fiber, preparation method thereof and pre-oxidation furnace for producing 35-50K carbon fiber

The invention belongs to the technical field of carbon fibers, and discloses a 35-50K carbon fiber, a preparation method thereof and a pre-oxidation furnace for producing the 35-50K carbon fiber, the preparation method comprises a pre-oxidation stage, and the pre-oxidation stage comprises the following steps: after a carbon fiber precursor enters the pre-oxidation furnace, firstly carrying out heat-moisture treatment on the carbon fiber precursor by using damp and hot steam, and carrying out heat treatment on the carbon fiber precursor subjected to heat-moisture treatment by utilizing hot air. After entering the pre-oxidation furnace, the carbon fiber precursor is firstly subjected to heat-moisture treatment by utilizing damp and hot steam, so that the elongation of the fiber is improved, the concentrated release of reaction heat in the production of 35-50K large-tow carbon fiber is relieved, and the carbon fiber precursor is subjected to heat treatment by utilizing hot air after the heat-moisture treatment,