Duske Triple-Pass Rotary Drying System has a stepped drying cylinder design that provides 7 drying zones (see illustration at left). A smaller inlet diameter results in high air velocities and high evaporation rates, which keep product temperatures relativly cool.

with advanced and proven triple-pass technology in Duske rotary dryer systems.

Triple Pass Drum

The seven drying zones gained through Duske’s stepped cylinder design start with a smaller inlet diameter that provides high air velocities and high drying rates in the high air temperature zone. This keeps product temperatures relatively cool, as known from sound principles of heat transfer.

In contrast, drums with large inlet diameters and low hot air velocities are less efficient because they require 30°- 60° F. higher dryer outlet temperature in order to obtain desired moisture content. Depending upon dryer size, this results in additional fuel cost of $5,000 - $30,000 per year at current fuel prices. This fact has been proven in actual plant operations drying blood and bone meal.