Reactions and Transformations of Mineral and Nonmineral Inorganic Species during the Entrained Flow Pyrolysis and CO2 Gasification of Low Rank Coals

Abstract

The reactions and transformations of mineral and nonmineral inorganic species in Victorian (MOR) and Rhenish (HKT) coals were investigated in a two-stage process under high temperature, entrained flow pyrolysis, and gasification conditions. The parent coals were pyrolyzed at a temperature between 1100 and 1400 °C in 100 vol % nitrogen. The resulting char samples were collected and gasified at their corresponding pyrolysis temperatures in 10–80 vol % CO2 in N2. Low temperature (500 °C) ash subsamples from the parent coals, chars, and gasification residues were analyzed for elemental and mineral phase composition. The phase composition analysis was in agreement with the proportions of various inorganic constituents in the elemental analysis. In general, the extent of reaction and phase transformation increased with increasing temperature and carbon conversion, which is related to increasing temperature and CO2 concentration. The char elemental and phase compositions were similar to those of the correspondin...