Changes in char reactivity due to char-oxygen and char-steam reactions using victorian brown coal in a fixed-bed reactor

This study was to examine the influence of reactions of char-O-2 and char-steam on the char reactivity evolution. A newly-designed fixed-bed reactor was used to conduct gasification experiments using Victorian brown coal at 800 degrees C. The chars prepared from the gasification experiments were then collected and subjected to reactivity characterisation (ex-situ reactivity) using TGA (thermogravimetric analyser) in air. The results indicate that the char reactivity from TGA was generally high when the char experienced intensive gasification reactions in 0.3% O-2 in the fixed-bed reactor. The addition of steam into the gasification not only enhanced the char conversion significantly but also reduced the char reactivity dramatically. The curve shapes of the char reactivity with involvement of steam were very different from that with O-2 gasification, implying the importance of gasifying agents to char properties. (C) 2014 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.