Oil shale project run summary, small retort: Run S-7

Run S-7 went smoothly except for loss of nitrogen flow for a short period early in the run. The thermal front developed rapidly and appeared to travel through the bed in a stable and uniform fashion. The exit gas composition stayed relatively constant for most of the last 3/4 of the run. The traveling temperature probe worked well and gave detailed and relatively accurate profiles of retort temperature. Analysis of gas taken from within the retort gave us some insight to the processes taking place within the bed, and indicated that oxygen disappears well before oil is produced and thus is unavailable for burning oil. Since the evidence from gas analysis is that oil is not burned, why is the yield only 78%? Some oil would be lost by coking and cracking, but laboratory studies indicate that this would be small at the retorting rates of S-7. The mass and energy balance results give some indication that we probably lost a portion of the oil up the stack. The mass balance shows that 2.5 kg or 1% of the oil is unaccounted for. This is a small amount; however, the energy balance shows that 66,000 kilojules or almost 10% of the input energy is unaccounted for. The carbon balance shows a similar result (10.5%). If we assume that the oil yield was actually 90% and that 1.3 kg of oil was lost up the stack, the mass balance would show a small improvement, 1.2 kg (approximately 0.5%) unaccounted for; but, the energy balance would now show only 6,800 kilojoules or 1% of the energy unaccounted for. The carbon balance similarly shows a reduction from 10.5% to 1.4%. There are no cold traps on the retort exit stream, and as subsequent results have shown, this has permitted a substantial loss of yield due to disappearance of product up the stack.