Retorting process utilizing a flexible, helical shaped conveyor

A continuous process for retorting shale which comprises:

• a. introducing spent shale at an elevated temperature in the range 1200.degree. to 1700.degree. F and hydrocarbon-containing shale at a temperature in the range 50.degree. to 750.degree. F into a first section of a stationary, substantially horizontal, elongated, cylindrically-shaped vessel;
• b. conveying said spent shale and hydrocarbon-containing shale through said vessel by means of a flexible, generally helical shaped, elongated, hollow longitudinal core rotating element whereby said spent shale and said hydrocarbon-containing shale are intermixed and sufficient heat is transferred from said spent shale to said hydrocarbon-containing shale to raise the temperature of said hydrocarbon-containing shale to a temperature in the range 875.degree. to 975.degree. F in said first section of said vessel;
• c. introducing a stripping gas at an elevated temperature in the range 875.degree. to 975.degree. F into a third section of said vessel downstream from the location where said hydrocarbon-containing solids are introduced, and passing said stripping gas through said third section of said vessel in countercurrent flow relative to the flow of said spent shale and said hydrocarbon-containing shale whereby said hydrocarbon-containing shale is maintained at a temperature of at least 875.degree. F in said third section;
• d. withdrawing at an elevated temperature in the range 875.degree. to 975.degree. F an effluent stream from a second middle section of said vessel, said effluent stream comprising said stripping gas, entrained liquid and gaseous hydrocarbons and finely-divided solids;
• e. separating the condensable hydrocarbons from said effluent stream;
• f. withdrawing at an elevated temperature in the range 875.degree. to 975.degree. F retorted shale containing essentially no volatilizable hydrocarbons and said spent shale from said third section of said vessel;
• g. passing said retorted shale and said spent shale into a combustion zone and combusting the residual carbon on said retorted shale forming spent shale at a temperature in the range 1200.degree. to 1700.degree. F;
• h. introducing at least a portion of said spent shale from step (g) into said first section of said vessel.