SOME EFFECTS OF BED PARTICLE PROPERTIES ON WEAR IN FLUIDIZED-BED COMBUSTORS

Serious wear of in-bed heat exchanger tubes in bubbling fluidized-bed combustors often occurs as the result of periodic energetic impacts by large aggregates of bed particles on the underside of tubes. The resulting ''hammering'' effect is simulated in a specially designed laboratory wear rig by quickly driving a specimen rod downward within a bed of fluidized particles. In this study, some of the ways in which.bed particle properties influence wear in this environment are examined. Bed particles of three different compositions were used in separate wear tests on aluminum rods at room temperature. The wear rates and wastage distribution about the rod circumference were strongly influenced by the type of bed particles used. The dependence of wear on impact energy also differed markedly with the composition of the bed. The differences were primarily attributable to the nature and degree of the fine bed particle debris formed through comminution and how it is incorporated into the surface of the wearing rod.