Fluidization characteristics of oil palm frond particles in agitated bed

Fluidization characteristics of crushed oil palm fronds were studied. The elongated shape of the particles and their fibrous nature created entanglement between the particles and caused the bed to form crack and plug flow when aerated in ordinary fluidized bed. Fluidization of the fibres became feasible with the aid of mechanical agitation. Agitation helped to loosen the entanglement of the fibres which prevents air to pass through the bed of particles, as a result, fluidization state could be attained. Experiments were carried out in a column with height of 72 cm and ID of 14.4 cm. Superficial air velocities used ranged from 0.1 to 1.1 m/s, bed heights ranged from 4 to 8.5 cm, agitation speeds ranged from 300 to 500 rpm and particle initial moisture contents from 0.5 to 2.4 g water/g dry solids. Analysis of the fluidization characteristics showed that minimum fluidization velocity was independent with bed height and agitation speed. However, investigation on the effect of particle initial moisture content showed that minimum fluidization velocity increased with particle moisture content. A new empirical correlation to predict minimum fluidization velocity has been derived which gives good agreement with experimental data in this study and the data from other study in the literature.

► Fluidization of oil palm fibres was possible by assisting with mechanical agitation.
► Minimum fluidization velocity is independent with bed height and agitation speed.
► Minimum fluidization velocity increases with particle moisture content.