Identifying the reaction mechanism of oil-shale self-heating retorting by thermal analysis techniques

Structural and quantitative evolution of organic matters in oil shale during two different retorting processes

“…Some of the studies are rarely conducted previously even for the traditional AR process. More fascinatingly, based on our previous studies that prove SHR greatly simplifies retorting process, 36‐41 this study further demonstrates that SHR also alleviates the environmental impact of the organic residue like toxic PAHs.…”

“…The raw OS was crushed and screened to 1–3 mm particles before used. The general SHR process has been described elsewhere 37‐39,41 . The retorting apparatus was similar to those used in our former work.…”

“…The topochemical reaction, different from physical heating or complete combustion, is a chemical heat‐enhanced process that not only conserves energy but also decomposes OS more thoroughly. Independently, we developed self‐heating retorting (SHR) that is a low‐energy input route but without marked loss in the oil yield 36‐41 . SHR is realized by using a certain amount of O 2 to exothermically react with OS that is previously preheated under N 2 .…”

“…Because OS can spontaneously increase its temperature to complete its pyrolysis in the absence of external heat provision, the retorting process is significantly simplified. Moreover, the obtained oil still mainly consists of various hydrocarbons, like that obtained from anaerobic retorting (AR), 33,36‐40 indicating that SHR does not cause an obvious oxidation of the produced oil. The further studies show that, in traditional AR process substantial carbon is formed and left in the semicoke byproduct without utilization, and its calorific value is enough for heating OS to above 1000°C 38,39 .…”

“…Semicoke is always abandoned or left underground 19 . This may be a waste of energy, as semicoke has relatively high char contents and still contains a certain calorific value 38‐40 . In other words, it is equivalent that SHR uses semicoke waste to in situ generate heat and replace electrical or other forms of heating, which might also prevent the heat loss owing to heat transfer via high‐temperate heat carrier in other technologies.…”