Fluidized Bed Drying

Fluidized bed dryers are used in a wide range of industries due to their large capacity, low construction price, easy operation, and high thermal efficiency. They fit any type of moist solid as long as it can work in regime of fluidization.

A new application for fluidized bed dryers has come along with biodiesel because an increase in methanol is noticed and, as a consequence, sugar cane bagasse production is also increased. This is normally used as fuel in the boilers of their own plants and distilleries. Even so, an approximate 30% surplus is observed. Such surplus can be used to substitute fuel oil in other industries as sugar cane bagasse presents an equivalent power cost lower than the cost of oil.  However, the bagasse is required to be dry and compact for transport purposes.

For the use of fluidized beds in bagasse drying, a few issues must be dealt with for the bagasse presents a highly cohesive behavior. This is so due to moisture and its highly specific area. Therefore, the presence of an agitator or a second solid in the bed may help contain agglomeration of particles and improve fluidization occurring without the formation of preferential channels.

he features of the bed change during the entire drying process due to the decrease of moisture. During particle drying, a decrease in the cohesiveness and elutriation of previously dried particles is noticed. Therefore, a cyclone is installed to separate the elutriated particles from moist air. From 35 to 90% of the solids can be usually elutriated.

Other applications can be found for sugar cane bagasse such as in the pulp and paper, blue boards, fertilizers or plastics production.