Oil shales from Colorado, Israel, Morocco, and the eastern U.S. Devonian and Mississippian were burned in a fluidized-bed combustion unit. The oil shales are devolatilized or retorted in the fluidized bed; the volatiles are burned over-bed for maximum heat recovery and/or the volatile can be condensed downstream for hydrocarbon fuels production.

An oil shale energy recovery process is proposed wherein pseudo, two-state combustion in a high freeboard fluidized-bed combustion unit is used. In this design, the volatiles are driven off with minimum calcination taking place in the spent shale. The volatiles are burned in the freeboard for maximum heat recovery. The burning fluidized bed will be shielded from the radiation heat generated by the freeboard combustion by a cloud of elutriating dust particles.

Experiments and analytical data leading to the conceptual design will be presented. Some of the oil shales have an inordinate amount of inert material with a high concentration of calcium carbonates. The amount of calcium sulfates exceeds the calcium carbonate required for sulfur retention.

When heating up to the temperature where the calcination of carbonates is taking place, considerable amounts of heat of combustion will be consumed by the heat from calcination. The conceptual design will heat the oil shale to a temperature at which the devolatilization or retorting is taking place without appreciable calcination. The control of calcination will reduce the heat consumption and increase the heat recovery.

The spent shale from fluidized-bed combustion can be used for cement manufacturing, the major component of construction materials. The use of oil shales as a source of cementitious material will help to solve the troublesome solid waste disposal problem.

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