Superatmospheric pressure shale retorting process

Claim 1

A shale retorting process which comprises: 1. gravitating crushed oil shale downwardly through a feed conduit into a feeder cylinder which alternately receives a charge of shale and then discharges the same upwardly by means of a reciprocating piston into the bottom of a communicating retort; 2. contacting the resulting upflowing shale in said retort with hot, downflowing eduction gases at superatmospheric pressures to educe product oil and gas from said upflowing shale, said oil and gas being discharged from the bottom portion of said retort into an isobaric product collection vessel in which a first liquid level of crude product oil is maintained; 3. maintaining substantially continuous hydraulic communication between the product oil in said collection vessel and the bottom of said feed conduit, whereby a second liquid oil level is maintained in said feed conduit, said second oil level being substantially above said first oil level and forming a hydrostatic seal against retort pressure; 4. transferring hot, retorted shale overflowing the top of said retort through a gas-tight transfer conduit to a water quenching zone in which is maintained a first liquid water level substantially below the top of the retorted shale bed maintained therein; 5. removing retorted shale from the bottom of said quenching zone through an upwardly extending outlet conduit communicating therewith below said first water level, whereby a second water level is maintained in said outlet conduit, said second water level being substantially above said first water level and forming a hydrostatic seal against retort pressure, the rate of removal of said retorted shale being controlled so as to maintain the top of said retorted shale bed substantially above said first liquid water level; 6. recovering a quench gas mixture of superheated steam, a combustible water gas and vaporized heavier hydrocarbons from the top of said quenching zone; and 7. recycling to said feed conduit sufficient of a light product oil recovered from said retorting to maintain said second oil level and to substantially prevent entry into said feed conduit of said crude product oil, said light product oil having a substantially lower pour point than said crude product oil.