Basics Of Grain Drying - Mepu K-SERIES Operating Manual

3 Basics of grain drying

The keeping quality of harvested grain depends on its moisture content and the grain temperature
achieved by the method of storage. Under the conditions in Scandinavia and the northern
hemisphere, the moisture content of grain after harvesting varies typically between 15–45%, which
requires taking measures to improve the keeping quality of grain. The climatic conditions in the
northern hemisphere prevent from achieving sufficiently low moisture content figures if just natural
drying processes are used. During the harvesting season the relative air humidity can reach as high
as 80–90%. Thus drying methods where no auxiliary equipment is used cannot produce low
moisture contents. Therefore grain has to be handled applying various methods in order to improve
its keeping quality. The established handling methods include various drying techniques and – in a
smaller scale – freezing of grain.
The functioning of dryers is based on strong air flows circulating through the grain batch being
dried, and subsequently discharging the air into the atmosphere. Dissipation of moisture can be
facilitated by increasing the temperature of the grain being processed. The homogeneity of drying
quality can be increased by circulating and cooling the grain during the drying process.
However, there are certain basic rules involved in the drying process, which should be observed to
prevent drop of grain properties, such as germinative capacity or baking properties. The most
important aspects that need to be monitored are grain temperature, circulation rate and air flow.
These values vary by individual grain types and the case-by-case temperature settings must be
determined through experience. The values are also affected by some dryer-specific aspects.
Approximate drying air temperatures:
50 ... 60
Seed grain
Bread grain 60 ... 70
... 80
Fodder grain
Recommended grain temperature:
o
C ... germinative capacity drops
Below 45
If drying is carried out in hot weather, make sure that the grain is circulated and dried property in
order to avoid overheating.
5
o
C
o
C
o
C
D00125-2019_EN