Panels & Furniture Asia March/April 2024

PANEL MANUFACTURING
Dynadryer:
IMAL belt dryer
if needed; the modular drying
unit can be extended to increase
drying capacity in the future. The
Dynadryer is also reportedly simple
to transport, shippable in a standard
container, rapid to install on site;
few structures are required and
no cyclones need to be fabricated
on site. A simple concrete base is
enough.
Two double deck
belt dryers under
construction
Belt drying technology originated
in North America a few decades
ago. Since then, it has undergone
improvements and the IMALPAL
Group, after installing its first belt
dryer in Europe 10 years ago, believes
that the belt dryer is the most
optimal, economical and safest drying
technology available on the market
today, in comparison to drum dryers.
The first IMAL belt dryer, the
Dynadryer, was installed on an
oriented strand board (OSB) panel
production line to dry strands to a
moisture content of approximately
2%. These dryers can also be used in
the panelboard industry as well as in
the production of pallet blocks and
pressed pallets. IMAL currently has
over 30 dryers in operation worldwide.
One of the main features of the
Dynadryer belt dryers is they run at
low temperatures of maximum 95°C:
The air is heated by hot air-water heat
exchangers where the temperature
of the water is around 100°C. This has
the additional advantage of minimising
fire risks, and emissions are so low
that a wet electrostatic precipitator
(WESP) is reportedly not required
either.
According to IMAL, the Dynadryer has
no volatile organic compound (VOC)
emissions, since temperatures are
below 100°C; there is no change in the
wood particle colour too after drying;
particles are not broken in the drying
process; less resin is required since at
a lower temperature, less wood resin
is lost or burned; and dust emission
from the chimneys is kept low, at
maximally 5mg/m 3 , or will not exceed
a “guaranteed” level of 10mg/m 3 ,
hence avoiding the need to install wet
electrostatic filters.
The Dynadryer also comes with a
simple drying automation process
with the possibility of varying belt
speed, m 3 /h for the fans, and water
temperature; it requires minimal
maintenance, with changes to the
perforated belt every five to six years,
The drying capacity of the Dynadryer
belt dryers ranges from a couple
of tonnes per hour of evaporated
water, up to 35 tonnes per hour per
dryer. These dryers may be single
deck or double deck in relation to
the evaporation capacity required.
In either case, since the belt dryers
are modular, they can be extended to
increase the evaporation capacity.
Each belt dryer is divided into
independent areas, each equipped
with its own heat exchanger units —
normally two — and fan.
The IMAL Dynadryer is flexible
and has the following automatic
regulations to achieve high
performance and low consumption:
variation of belt speed to vary the
time the material remains inside
the dryer, and hence the drying
time; variation of fan speed to
vary the amount of drying air; and
variation of water flow to the heat
exchangers, which in turn changes
the temperature of the drying air.
The moisture content of the
material at the outfeed and the
temperature of the exhaust gases
are monitored. Lastly, in the event
of any unexpected problems arising
with the equipment downstream, the
belt dryer can be stopped instantly
with material inside, without running
a fire risk and without having to
empty the material out. In this case,
belt dryer acts as an additional
buffer. In terms of thermal power
requirements, the IMAL belt dryer
is comparable to standard drum
dryers, consuming on average 0.9Mw
per tonne per hour of evaporated
water.
30 PANELS & FURNITURE ASIA | MARCH / APRIL 2024