Generally the chamber design depend s on the atomizer
used and on the air–fluid con tact system selected. The
selection of atomizer and air–fluid layout is determined
by the required characteristic s of the dry product and production rate. The product specifications
are almost always determined from small-scale test s
in an experimental spray dryer. Sometimes they are
available from the literature. If heat- sensitive material
is involved, attention must be paid to the temperature
profile of the drying air along the drying chamber.
Another area that requires attention is the droplet
trajectory, mainly the trajectory of the largest drop s
as the size of chamber must be such that the largest
drop in the spray is dry be fore it reaches the chamber
wall. This requirement prevents the formation of partially
dried material buildup on the chamber walls. The
height H of the drying chamber as a function of droplet
diameter d and temperature differences DT between
the drying air and the particle is shown in Figure 10.13.