Shale retorting process

A continuous process for retorting oil shale which comprises:

• (a) introducing a solid heat-transfer material at an elevated temperature in the range 1000.degree. to 2000.degree. F and oil shale into a lower portion of a first vertically elongated vessel at a weight ratio of said heat-transfer material to said oil shale of greater than 0.1 and less than 5;
• (b) passing a lift gas containing less than 1 volume percent free oxygen upwardly through said first vessel at a linear velocity of 20 to 200 feet per second and sufficient to entrain and convey said oil shale and said heat-transfer material upwardly through said vessel, whereby said oil shale and said heat-transfer material are intermixed and said oil shale is rapidly heated to an elevated temperature between 700.degree. F and 1200.degree. F, vaporizing a first portion comprising less than 30 weight percent of the hydrocarbons in said oil shale, said oil shale having a residence time in said first vessel of less than 5 seconds;
• (c) separating from said lift gas a solid fraction comprising said heat-transfer material and oil shale;
• (d) introducing said solid fraction into the upper portion of a second vertically elongated vessel forming a downwardly moving bed of solids wherein additional heat is transferred from said heat-transfer material to said oil shale, vaporizing a second portion of the hydrocarbons in said oil shale;
• (e) withdrawing retorted solids and said heat-transfer material from a lower portion of said second vessel;
• (f) passing a stripping gas upwardly through said second vessel which entrains said vaporous second portion of hydrocarbons;
• (g) separating condensable hydrocarbons from said lift gas and said stripping gas;
• and
• (h) introducing retorted solids into a lift pipe combustor and combusting residual carbon in said retorted shale, forming spent shale at an elevated temperature in the range from 1000.degree. F to 1600.degree. F, and introducing said spent shale into said first vessel to provide said heat-exchange material.