Basic mechanism to achieve clean combustion of oil shale in fluidized beds

Results are presented of a study undertaken to analyze and assess fluidized bed oil shale combustion, particularly from an environmental standpoint. Oil shales are classified and characterized and their properties are described. Attention is focused on mineralogical composition, porosity, specific gravity, specific heat, calorific value, thermal conductivity, trace metal content, and sulfur and nitrogen content. The mechanisms and kinetics of oil shale retorting and combustion are discussed. The clean combustion of oil shale is examined and fluidized bed oil shale combustion is explored. The simulation of oil shale combustion in a fluidized bed, 6 inches in diameter, is described. The advantages of combustion in a fluidized bed are listed, including: (1) fluidized beds can be effectively used to burn oil shale to produce heat or steam at a high combustion frequency and (2) gaseous pollutants can be removed during combustion inside the bed. Disadvantages are noted, including: (1) the spent shale from a 10-ton steam/hour boiler is estimated to be 78 tons per day at the fresh oil shale feed rate of 104 tons per day; and (2) the fluidized bed must be maintained at a relatively low temperature of 810C.