Influence of Temperature on the Release of Inorganic Species from Victorian Brown Coals and German Lignites under CO2 Gasification Conditions

Abstract

The release of volatile inorganic species containing Na, K, S, and Cl during coal gasification is of interest due to the known associated issues related to corrosion and fouling in coal-to-product processes. Therefore, laboratory-scale experiments using two Victorian brown coals and four German lignites were performed at 1100, 1200, and 1400 °C under an atmosphere of 20% CO2 in He to simulate gasification conditions. The reaction products were analyzed online by the well-established molecular beam mass spectrometry technique, and qualitative and semiquantitative analysis of the results was performed. The primary release occurred during the initial devolatilization phase, with less volatile and secondary products released during the gasification phase. The main inorganic species detected were 34H2S+, 35Cl+, 36HCl+, 39K+/39NaO+, 58NaCl+, 60COS+/60NaCl+, and 64SO2+. The release of sodium and chlorine species was highly dependent on temperature and the inherent Al and Si content of the coals. The release of sulfur-containing species was highly dependent on temperature and the inherent Ca content of the coals. Mechanisms for the initial release and subsequent reaction of intermediate inorganic species are offered herein to explain the observed trends with temperature and coal properties.