| 摘要 |
<p>Process for in situ retorting of oil shale, wherein retorting is carried out through a bed of broken pieces of shale, with pillars of unfragmented raw shale provided between the oil shale retorts. This is accomplished according to the invention by establishing an additional or secondary combustion zone above the primary combustion zone therein and preferably near the top of the oil shale retorts. In one embodiment the secondary combustion zone is maintained by introducing into the top of the retorts shale oil produced from retorting, together with air and combustible off gas from retorting. The supply of shale oil to the top of the retorts is discontinued when the heating value of off gas from the retort is sufficient to provide the minimum combustion temperature of the gas introduced into the top of the retort.</p> |
