Absorber: In the absorber column the refrigerated feed gas and lean oil are intermingled at a temperature of minus 35 deg F to allow the lean oil to absorb the LPG products of propane and heavier components from the gas and become a rich oil.
Rich oil still column/hot oil system: In the rich oil still, lean oil is separated by distillation from the absorbed LPG products.
The lean oil shale layer, lying under the rich oil shale, has the average thickness of about 30 m.
stripping process, including hole drilling, blasting, quarrying, transporting, and dumping (to the dumping yard with sand, rocks, lean oil shale, etc.
However, leading research institutes are not expecting oil markets to "nose-drive," as in 1998, because of relatively lean oil
The process is suitable for retorting high-calorific oil shales (over 15% of Fischer assay oil) and bituminizing oil shales as well as for lean oil shales.
In experiments of processing lean oil shale by vertical retorts in Kivioli with cross-flow of heat carrier, their average daily throughput remained low (160-180 tpd) compared to concentrated oil shale at Kohtla-Jarve (200 tpd).
A serious problem in using large deposits of lean oil shale is the development of vertical retorts designed for high throughput.