| Description |
An indirect thermal method for recovering bitumen from oil-impregnated rock or tar sand using a two-stage, fluidized-bed reactor is developed. Ground tar sand is fed into a coking bed with a screw conveyor, where the bitumen is cracked, releasing volatile hydrocarbons and coating the sand particles with a carbon residue. The coked particles flow into a combustion bed, located directly below the coking bed, through a solids control valve, where they are combusted with air to provide heat for the process. The oil product passes through a series of high-temperature cyclones and a filter for dust removal and is recovered by condensers, a cyclone separator, and an electrostatic precipitator. When processing Utah tar sand from the Tar Sand Triangle deposit, the bitumen product has an average viscosity of about 400 cp (25°C), an API gravity of between 10.3 to 15.8, and a carbon-to-hydrogen ratio between .63 to .68. This product compares favorably with those obtained by others from Athabasca bitumen, processed in a similar manner. The major advantages of fluidized thermal recovery of bitumen as compared with the Hot Water Extraction Process are (1) low requirements for process water, (2) ease of product and byproduct handling and disposal, and (3) processability of lean tar sands. |
