Sulfur release behavior during pyrolysis of a Bituminous coal fractions: The relationship with sulfur forms, char particle size distribution and morphology, and char conversion.

Investigation of sulfur release from coal during high temperature gasification is crucial to designing control measures for fouling and corrosion-related issues, and for developing hot-gas-cleaning research strategies. The aim of this study is to investigate the release of sulfur as a function of initial coal particle sizes (PS6: 75-106 μm, and PS3: 212-420 μm), density of coal fractions (SG1: <1.3 g/cc, SG2: 1.3-1.6 g/cc, and SG3 (mineral rich fraction):1.6-2.6 g/cc), and temperature (1573 K, 1673 K, 1793 K) under reducing atmosphere (mixture of N₂, H₂O and CO₂) in a laminar flow furnace with an overall objective of arriving at a detailed sulfur release mechanism at high heating rates. The results show that the release of sulfur is strongly influenced by the initial coal particle size (PS6>PS3), char fragmentation, temperature (1793 K>1673K>1573K), and sulfur forms. The strong correlation between char particle size distribution and sulfur release indicates that the mass transfer limitations play an important role in the release of sulfur. Besides mass transfer limitations, the sulfur forms also seem to play an important role with sulfur from pyrite being released at a greater proportion. The other parameter that could affect the sulfur release is minerals in high-density fraction. However, at this point it is not clear to what extent minerals play a role in the release of sulfur. More experiments will be conducted to arrive at a detailed sulfur release mechanism during pyrolysis.