Experimental study of the autothermic pyrolysis in-situ conversion process (ATS) for oil shale recovery

Abstract

Oil shale has not been applied in large-scale industrialization due to its poor efficiency and high energy extraction cost. The autothermic pyrolysis in situ conversion process (ATS) is an oil shale high-efficiency heating method that uses the residual potential heat after kerogen pyrolysis. In this study, one-dimensional oil shale in situ pyrolysis experimental apparatus is designed to study the feasibility, characteristics, and energy efficiency of ATS. The results show that the ATS of oil shale is successfully triggered at 300 °C. The peak surface of autothermic pyrolysis is steadily advancing, proving the feasibility of the method in laboratory-scale experiments. According to the optical characteristics and chemical composition, ATS can be divided into five typical reaction zones: (a) residue zone, (b) autothermic zone, (c) cracking zone, (d) preheating zone, and (e) virgin zone. Compared with the high-temperature nitrogen in situ conversion process (HNICP), pyrolysis oil obtained from ATS contains more light components. When the oil recovery from ATS reaches 97.1%, the energy efficiency reaches 3.46, which is much higher than that of 0.51 for HNICP. This study shows the advantages and feasibility of ATS experimentally, which can be used for the large-scale commercial development of oil shale.