Computational fluid dynamics and tar formation in a low-temperature carbonization furnace for the production of carbon fibers

A three-dimensional computational fluid dynamics (CFD) model with new permeability and off-gas emission equations was developed in a four-zone low-temperature furnace (LTF) for carbon fiber carbonization. Four performance criteria (residence time, dead-volume ratio, tow temperature standard deviation, and tar formation area) were proposed to identify the optimal ratio between the two N-2 flow rates introduced into the front and rear of LTF. A higher N-2 flow rate at the front rather than at the rear was preferred to reduce tar formation. The tar formation area calculated from carbon activity provides useful guideline for determining optimal LTF design and operating conditions. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.