AbstractThis paper presents a study on the burning of oil palm empty fruit bunch and palm kernel shell in a fluidized-bed combustor using alumina sand as the bed material to prevent bed agglomeration. During 60-h combustion testing, the biomasses were burned at similar heat input to the combustor (200 kWth) with excess air of 40%. SEM/EDS analyses were performed to investigate the time-domain changes in the alumina grain morphology and elemental composition of the grain coating. Composition of the used/reused bed material and that of PM emitted from the combustor were determined by a XRF method at different operating times. No features of bed agglomeration were found during the entire tests. However, physical and chemical properties of the bed material underwent substantial changes with time.