The effect of mass transfer conditions during plastic stage on sulfur removal from high organic-sulfur coal.

A gas coal (B) was used to study the effect of volatiles on sulfur removal from a high organic-sulfur coking coal (A) from the perspective of mass transfer conditions. The mass transfer driving force and resistance of volatiles were analyzed in terms of fluidity development, permeability of coal plastic stage to gas flow, and volatile matter release. Carbonization using vertical and horizontal stacking modes of two coals were designed according to the release directions of volatiles during pyrolysis. Three pyrolysis temperatures (450, 475 and 510 ºC) were used to study mass transfer conditions. The semicokes were cut into pieces at fixed intervals along vertical and horizontal directions to determine the spatial sulfur distribution in semicoke. The gas coal volatiles helped the removal of sulfur within a limited distance that was related to the mass transfer conditions of volatiles, whereas permeability determined the mass transfer resistance of volatiles and their driving force was controlled by the amount and rate of volatile matter release. • Mass transfer conditions of volatiles vary with permeability of A and volatile evolution of B. • Volatiles of B remove sulfur within effective distances in vertical and horizontal directions. • Favorable mass transfer conditions extend release distance but reduce the reaction time. • Low permeability of plastic stage of A makes sulfur removal gentle but continuous. [ABSTRACT FROM AUTHOR]