Continuous conveyor dryers are up to 20 m long and 3 m wide. Food is dried on a mesh belt
in beds 5-15 cm deep. Wet material supplied to the spreader device at the left-hand end is
loaded evenly and in a relatively deep layer on the surface of a slowly moving conveyor belt
(Figures 2 and 3). The air is initially directed upwards through the bed of food and then
downwards the last 1 or 2 sections so as to prevent light-weight, nearly dry pieces from
blowing out of the bed, although sometimes the drier is designed to produce up-through and
down-through flow in alternate sections in order to improve the uniformity of drying of a
thick layer of wet material. Sectionalising the drier makes it possible to control air
temperature, humidity, and velocity independently in several stages to give optimum output