The ignition and combustion behavior of spent shale particles

Abstract

This study examines the ignition and burning of chars left after pyrolysis of 5 cm diameteroil shale samples. The experiments modeled in-situ retorting by minimizing radiation. The effects of shalegrade (from 83 to 183 liter/tonne), retorting temperature (600 to 756 K), and combustion gas composition (5 to 21% O2) were examined. This study confirms the important role of gasification of the char by CO2 released from decomposition of carbonate minerals and explores the transition to that mechanism for the initial direct attach of O2 on char. This transition is normally encountered in combustion of chars produced from rich shales. The role of CO combustion within the rock matrix is also considered. The model is presented which successfully predicts the temperature histories and conversions of the spent shales, as well as the change from the direct oxidation mechanism to the gasification mechanism described above. © 1982 Combustion Institute.