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Effects of interactions among coals on the caking ability of blends during carbonization

Jiao, Haili, Wang, Meijun, Kong, Jiao, Guo, Jiang, Chang, Liping
Journal of analytical and applied pyrolysis 2019 v.138 pp. 154-160
carbon, carbonization, coal, feedstocks, gasification, oxygen, pyrolysis
The inferior coking coals as feedstocks to produce char for gasification is an effective way of utilizing the excess coking capacity and the low rank coal. Caking ability of coal is important to the characters and structures of char. For coal blends, it is affected by interactions among coal species. In this study, three different rank coals were selected to explore how the interactions among coals affect the caking ability of blends. The caking ability was evaluated by the caking index (GR.I) and the interactions were analyzed by the comparison between the experimental GR.I and theoretical one. The significantly interactions from greater and less GR.I values of the blends than those of the coals acting independently were observed and they relied on the coal types and ratios in blends. The coal species in blends played the positive effect of the interaction when the experimental GR.I value was greater than 45 of the blends. The increase of fat coal and the decrease of sub-bituminous coal and gas coal strengthened the caking ability and the swelling property of the coal blends. Oxygen content, carbon aromaticity and volatiles of single coal in blends are regarded as the factors to control the interactions of coals and the caking ability of blends.