A drum dryer consists of one or two horizontally mounted
hollow cylinder(s) made of high-grade cast iron or
stainless steel, a supporting frame, a product feeding
system, a scraper, and auxiliaries. Typical structures of
single and double drum dryers are shown in Fig. 1. The
diameter of typical drums ranges from 0.5 m to 6 m and
the length from 1 m to 6 m.
In operation, steam at temperature up to 2008C heats the
inner surface of the drum. The moist material is uniformly
applied in a thin layer (0.5 mm–2 mm) onto the outer drum
surface. Most of the moisture is removed at water boiling
temperature. The residence time of the product on the
drum ranges from a few seconds to dozens of seconds to
reach final moisture contents of often less than 5% (wet
basis). The energy consumption in a drum dryer may range
between 1.1 kg steam per kg of evaporated water and
1.6 kg steam per kg of evaporated water, corresponding to
energy efficiencies of about 60%–90%.
[2 – 4]
Under ideal
conditions, the maximum evaporation capacity of a drum
A drum dryer consists of one or two horizontally mounted
hollow cylinder(s) made of high-grade cast iron or
stainless steel, a supporting frame, a product feeding
system, a scraper, and auxiliaries. Typical structures of
single and double drum dryers are shown in Fig. 1. The
diameter of typical drums ranges from 0.5 m to 6 m and
the length from 1 m to 6 m.
In operation, steam at temperature up to 2008C heats the
inner surface of the drum. The moist material is uniformly
applied in a thin layer (0.5 mm–2 mm) onto the outer drum
surface. Most of the moisture is removed at water boiling
temperature. The residence time of the product on the
drum ranges from a few seconds to dozens of seconds to
reach final moisture contents of often less than 5% (wet
basis). The energy consumption in a drum dryer may range
between 1.1 kg steam per kg of evaporated water and
1.6 kg steam per kg of evaporated water, corresponding to
energy efficiencies of about 60%–90%.
[2 – 4]
Under ideal
conditions, the maximum evaporation capacity of a drum
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