Irati Energy Development of the Oil Shale Resources Near Curitiba, Brazil

摘要

When rubblizing oil shale to create a retort bed, the particle size distribution (PSD) will govern the void fraction (VF) in the bed. Void fraction is an important performance and economic variable, and process optimization requires that voids be controlled. Because oil shale particles fracture in shapes not readily described mathematically, an empirical approach has been taken to understand the relationship between PSD and VF. Particle shapes typically exhibit a long axis, a short axis and an intermediate dimension that define aspect ratios. Interestingly, for particles crushed only one or two times, the relationship of these axes dimensions are similar, irrespective of particle size. The consistency in aspect ratios allows for scaling of results from laboratory to field practice. Repeated crushing, however, changes these relationships and should be avoided. Particles of uniform size exhibit void fractions of 50% or greater. Lower void fractions can only be achieved through a proper recipe of a wider range of particle sizes. Particles varying in size by a factor of 100, mixed in ideal proportions yield void fractions as little as 20%. Results describing the PSD required to minimize void fraction have been developed and will be presented. The effect of void fraction on bed settling properties will also be illustrated.