Co-current combustion of oil shale – Part 1: Characterization of the solid and gaseous products

Co-current combustion front propagation in a bed of crushed oil shale (OS) leads to the production of liquid oil, of a flue gas and of a solid residue. The objective of this paper was to provide a detailed chemical characterization of Timahdit oil shale and of its smoldering combustion products. The amount of fixed carbon (FC) formed during devolatilization is measured at 4.7% of the initial mass of oil shale whatever the heating rate in the range 50–900 K min−1. The combustion of oil shale was operated using a mix of 75/25 wt. of OS/sand with an air supply of 1460 l min−1 m−2. In these conditions, not all the FC is oxidized at the passage of the front, but 88% only, with a partitioning of 56.5% into CO and the rest into CO2. A calorific gas with a lower calorific value of 54 kJ mol−1 is produced. Approximately 52% of the organic matter from OS is recovered as liquid oil. The front decarbonates 83% of carbonates.