04/02267 A novel process for stationary hydrogen production: the reformer sponge iron cycle (RESC): Hacker, V. Journal of Power Sources, 2003, 118, (1–2), 311–314

Abstract

Hot-compaction behaviour of semi-anthracite, low-, medium- and high-volatile caking, oxidized medium-volatile, sub-bituminous and lignite coals was studied under a constant load of 3.45 MPa. Generally, total compaction decreased and initial compaction temperatures increased with increasing coal rank. Initial compaction of the caking coals was noted at temperatures below their Ruhr dilatometer softening temperatures. For the high-volatile sample, this softening temperature was low enough, at about 250 °C, to imply possible thermal breakdown of such coals in preheating processes used before coke-making. The visco-elastic behaviour of coals of different rank over a range of temperature was examined. Densification mechanisms are suggested and the rate-controlling steps are discussed. Devolatilization is an important factor in particle-flow and shrinkage/dilatation mechanisms, as inferred from the similarities of the activation energies associated with these mechanisms and the reported values for devolatilization processes. Non-caking coals exhibit visco-elasticity at temperatures where they are expected to be semi-chars, in contrast with the caking coals.