| 摘要 |
An improved retort process in which oil is recovered from crushed oil shale moved by gravity through a passageway of an elongated housing with an inlet for the crushed oil shale at the top end and an outlet for the spent crushed oil shale at the bottom end of the housing, with the rate of movement of the crushed oil shale through the passageway in the housing being controlled. Heat is transferred in sequence to or from the ground oil shale as it moves from the inlet to the outlet by means of heat exchangers which are spaced to define a drying zone, a preheating zone, a cracking and distillation zone. Waste heat recovered from the waste heat recovery zone is passed to the preheating zone. Sufficient heat is delivered to the cracking and distillation zone to raise the temperature of the crushed oil shale moving through the cracking and distillation zone to the critical temperature for separating hydrocarbons in vapor form therefrom by means of an auxiliary heating assembly. The mixture of hydrocarbon vapors and gases released from the moving and heated crushed oil shale is withdrawn by a separating device, which condenses and removes hydrocarbons from the mixture. Additionally, a predetermined operating pressure is maintained in the respective preheat zone and the waste heat recovery zone, and the pressure in the cracking and distillation zone is controlled in response to the pressures sensed in the other zones and greater than such pressures.
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