Attrition of lime sorbents during fluidization in a circulating fluidized bed absorber

The experimental data of lime sorbent attrition obtained from mechanical and thermal attrition tests in a circulating fluidized bed absorber (CFBA) are represented. The results indicate that the predominant attrition mechanism during lime fluidization is surface abrasion due to collisions of the parent solids in a bed. Attrition of lime at higher temperatures decreased due to its hardened properties with rising temperature, while such solids as limestone become more attritable by the crepitation resulting from the increased internal pressure. With an introduction of the minimum weight of parent solids, the attrition rate of lime in a CFBA has a first-order dependency with respect to time. The attrition rate constant is expressed in an Arrhenius form, using the kinetic model which relates the attrition rate to the gas properties such as temperature and molecular weight and the geometry of the fluidized bed as well as the fluidization velocity. The experimental data obtained from these tests in a CFBA agree well with the attrition model, and the model indicates trends due to increased temperature considering thermal attrition. From the model the attrition activation energy, E[sub a] and k[sub o], can be obtained as E[sub a] = 3.383 [times] 10[sup [minus]3] kJ/kg and k[sub o] = 1.29 [times] 10[sup [minus]4]s[sup [minus]1], Comparisons of the mechanical and thermal attrition data obtained experimentally with the theoretical values computed with the attrition activation energy, E[sub a] and k[sub o], are in good agreement, and thus the results may be applicable to lime attrition in a fluidized bed.