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large woven wire-mesh screen that periodically must be re-
moved and cleaned manually.
• BKG ® Combi Series: new water-filtration options. BKG®
Combi-Line™ systems, also with capacities up to 2,000 kg/hr,
combine all of the features of the BKG® Master-Line™ system
and are available with an optional curved fines removal sieve.
More advanced is the BKG® Combigon™ system, which incor-
porates the BKG® Polygon™ automatic filter as standard equip-
ment and is available with an optional belt filter.
• BKG® Opti Series: top-of-the-line water system. Available in
models with capacities ranging up to 15,000 kg/hr. BKG® Opti-
Line™ systems include noise reduction of the centrifugal dryer,
pre-dewatering to enhance dryer efficiency, dryer window and
lights, and self-cleaning of the centrifuge. Also available as an
option is a curved fines removal sieve. Larger-capacity systems
are available on request.
A more advanced system is the BKG® Optigon™, which comes
with the BKG® Polygon™ automatic filter as standard equip-
ment and is available with an optional belt filter.
BKG® Polygon™ filtration system: key to energy savings
The BKG® Polygon™ water filtration system is an automated,
self-cleaning, tempered water system that minimizes operator
intervention and reduces overall pelletizer energy consumption
by ten to 17 percent.
One key to these benefits is the elimination of the need for a
separate fines-removal sieve, which in standard systems re-
quires a secondary, dedicated water pump. Instead, all filtration
is provided by a Polygon drum filter, which due to the large fil-
tration area can be equipped with 70-µm screens compared to
150-µm screens used in standard systems. Driven by a small
motor, the drum rotates within the water that is circulated
throughout the pelletizing system by the main process water
pump. The filtration system is designed so that dirt and fines
stay confined inside the drum until they are evacuated into a
collecting basin outside the tank. In effect, a small motor plus
gravity facilitates the fine filtration of the process water.
By eliminating the secondary pump, the BKG® Optigon™ water
filtration system uses only 1,440 KW per year (measured at
8,000 hours), as against 44,000 kW for the BKG® Opti-Line™
system with curved sieve. Since water filtration typically ac-
counts for ten to 17 percent of the energy consumption in un-
derwater pelletizing, the energy efficiency of the BKG ® Opti-
gon™ system means that overall consumption is cut by nearly
that much.
Substantial energy cuts in PET production
A patented process developed by Nordson specifically for PET
production dramatically reduces energy costs by producing and
crystallizing pellets in a single integrated process. Called BKG®
CrystallCut®, the process uses the thermal energy of the molten
polymer in PET pelletizing for subsequent crystallization, avoid-
ing the need to cool PET after pelletizing and then reheat it for
crystallization.
As an integrated network that incorporates underwater pelle-
tizing, drying, and crystallizing, the BKG® CrystallCut® process
is designed for precise control of material temperatures
throughout the process, preventing production and quality pro-
blems caused by insufficient crystallization and excess levels of
amorphous material. The energy efficiency of the BKG®
CrystallCut® system can save more than 3,000,000 EUR in an-
nual energy costs for a typical PET resin plant and nearly
200,000 EUR for an extrusion line recycling PET bottle flakes,
according to examples based on actual commercial installa-
tions.
Because the system utilizes residual thermal energy within the
material to crystallize pellets from the inside out, it yields an en-
hanced crystalline structure that results in lower energy costs
for re-melting the mterial. In addition to saving energy costs
and preventing amorphous PET clumping, the BKG ® Crystall-
Cut® process yields an almost dust-free product and increases
bulk density by eight percent in comparison with a conventio-
nal process.
Master-Line System
with Belt Filter
Schematic of CrystallCut Process
Nordson Corporation
,
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