World Grain - June 2021 - 78

TECHNICAL PROFILE: TROPICAL GRAIN STORAGE CHALLENGES
number of broken grains and energy consumption need
to be minimized. Bühler GmbH offers a solution for fast
but simultaneously gentle continuous drying of paddy,
consisting of a sequence of drying and tempering steps.
In the drying steps, the paddy is dried at tailored temperatures
depending on the respective moisture levels. In
the tempering steps between the drying steps, the moisture
can distribute homogeneously within the paddy
kernel to minimize the creation of brokens. Compared
to conventional processes, this principle saves around
20% of energy at a given higher yield, as the amount of
brokens is reduced.
Tropical regions also see many types of biomass
A tropical climate
like the
Philippines
needs effective
dryers to
maintain grain
quality.
Drying of wet grain down to storage moisture is necessary,
and this process step has a huge impact on grain
quality.
In tropical countries traditional drying methods,
such as sun-drying on the ground - for example, on
the street - are still common. But while this is a cheap
way to gently dry the crop, it does mean animals can eat
the grain. It is also an unhygienic drying process, due to
contaminations and pests, and heavy rains can interrupt
the drying. The yield is low, the grain is not dried homogeneously,
and the storage stability is questionable.
Compared to this, industrial drying processes are much
more stable and hygienic. Bühler GmbH's industrial
dryer, for example, dries at high capacity, maximizing the
grain's homogeneity and therefore quality, while at the
same time minimizing energy consumption and costs.
To achieve homogeneous drying of the grain and
maximum product quality, an optimal airflow within the
dryer's product column is needed - one way to achieve
this is Bühler's patented diagonal arrangement of conical
ducts.
A product flow separation step in the drying column
also acts as a static mixer, for further improved homogeneity.
A perfectly homogeneous drying process not only
leads to an optimum product quality but is also highly
energy efficient. So, in a controlled way the grain is gently
dried to the required storage moisture level.
Grain drying
The drying of paddy can be challenging. Even when drying
with large capacities, drying speeds are high, and the
78
used to fire heat sources, and Bühler dryers can be flexibly
operated with a huge variety of sources, for example,
with steam heat exchangers or indirect biomass
furnaces. When appropriate, gas or oil heat sources
also may be used.
To protect the environment and to comply with increasingly
strict exhaust air regulations, Bühler's exhaust
air handling system minimizes the dust in the
exhaust air (< 20 mg/m3 for all grains other than paddy
and < 50 mg/m3 for paddy).
Finding skilled operators can be difficult, driving the
desire for excellent drying results that can be achieved
independently of the operator. Bühler's DryMate enables
the plant manager to achieve optimal drying
results and boost the crop's quality and yield while
minimizing energy consumption. DryMate is a digital
service comprising an automatic moisture control allowing
for automatic drying to the target moisture, as
well as dashboards and mobile view for full process
transparency and customized tech reports to support
the plant's continuous improvement.
Grain temperature
When storing the material, it is necessary to avoid the
creation of hot spots that can cause the degradation of
the grain. Keeping the material at lower temperatures
means the storage time can be maximized and infestation
by pests can be avoided. Given high ambient air
temperatures, mere aeration may not be sufficient or
may even be harmful due to the warm and humid air
entering the silo.
In these cases, the use of one or more coolers is necessary.
Here, basically three factors must be managed
- temperature, moisture and storage time. Low temperature
and low moisture content allow for substantially
longer storage times and vice-versa. This is key
to success for grain conservation under tropical ambient
conditions with high moisture and temperature over
most of the day.
Bühler has built up extensive knowledge of the key
factors that need to be considered for proper storage,
June 2021 / World Grain / World-Grain.com
http://www.World-Grain.com
World Grain - June 2021

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