Experimental study on the fluid dynamics of orange bagasse in fluidized bed

Abstract

Orange is widely used worldwide for juice production, and in this process almost half the fruit is discarded as residue. The use of orange bagasse as biomass for energy production requires the reduction of its high moisture content. Aiming to evaluate the potential use of the fluidized bed technology for drying orange bagasse, it is essential to understand the hydrodynamics behavior of the material inside the bed, in order to know both the processing capability and optimum operating conditions of the equipment. Thereby, in this work the hydrodynamics characteristics of the orange bagasse were determined. How the fluidization parameters were affected by particle size and bed load were also evaluated. Experiments were conducted with bed loads of 400, 700 and 1000 g, and average particle diameter of 1,55; 1,85 e 2,58 mm. Increasing the particle diameter from 1,55 to 2,58 mm led to an increase in the minimum fluidization velocity (v_mf) from 1.36 to 1.83 m/s. Although particles having diameter of 2.58 mm require a higher air velocity to start fluidization, they presented the highest value of fluidization index and the lowest value of Froude number, thus being the most adequate for the fluidized bed operation. The pressure drop at the minimum fluidization increased 126% with the increase in the mass of 2.58 mm particles fed into the bed from 0.4 to 1 kg. However, there is no significant change in the minimum fluidization velocity for the different bed loads.