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By David Phillips,
Heyl & Patterson lnc.
ecause an industrial dryer is a
major capital investment lor any
organization,
it
pays
to
select
and test the unit carefully. Dryer life can
be measured in decades, so the selection
of inefficient equipment can have a longterm impact on the economic health of
the facility that houses it. The selection
of drying equipment is predominantly
an exercise in which knowledge, experience and science all play important roles.
of the complexitv of the drying
many
factors need to be considprocess,
Because
ered and weighed.
Before choosing an industrial dryer, con-
duct a preliminary analysis of your drying
needs. Ask questions about your material,
the production and final product quality
requirements, and your plant.
Think about the characteristics of the material to be dried. ls it wet or dry? What is
the particle size distribution? A material's physical or handling characteristics will
eliminate some dryers from consideration.
www.process-heating.com
. June 2013
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27
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When sele Ct ing a new dryer, consider whether existing ancillary items can handle the
pacity.
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dry or become contaminated during drying? How uniform must its final moisrure content be?'lrhat should the final
product temperature and bulk density
be? W'ill the dried material give off dust
or require solvent recovery?
Plant. How much space is available in
the plant? How warm, humid and clean is
the plant air?'$7hat fuel and power sources,
wet feed sources and exhaust gas outlets are
available in the plant? 'What levels of noise,
vibration, dust and heat loss are permis-
in the plant according to local zoning
and environmental regulations?
By answering these questions, vou rvill
rule out many dryers that are not suitable
for your application. For instance. a matesible
rial's physical or handling characteristics
will eliminate some dryers. A sterrm-tube
rotary dryer is not a good choice fbr a s'et,
sticky material such as mica. The dn,er
moves material by rotating and rolline it,
and such passive convevinq cannot move
a
sticky material our of the inlet area befbre
it cakes on the r.essel rvall and steam tubes.
A screw conveyor or indirect multiple
disc dryer is a better choice. Either unit
provides positive displacement that can
quickly move the mica away from the
inlet and toward the outlet.
Next, consider the footprint or
required floor space of the remaining
dryers that meet your requirements. Rule
out any dryer that does not fit the existing space or would require a costly plant
renovation or expansion. Compare the
capital and operating costs and performance of the remaining candidates.
If you are selecting a high-performance dryer ro upgrade your existing
drying process, consider whether existing ancillary items such as storage and
receiving equipment, conveyors and pollution control equipment can handle the
new dryer's increased capacity.
Once the field o[dryer choices has been
narrowed, test the dryers with your material under your operating conditions.
Dryer tests can be conducted in a pilot
plant lab faciliry and should establish:
.
The optimal operating conditions for
your material.
.
.
.
How well each dryer handles the material's physical characreristics.
The materialk qualiry and characteristics
after drying.
The appropriate dryer size.
Based
on these results, a dryer manu-
Facturer can develop detailed recommen-
dations for equipment that will meet
your drying needs. \With recommendations in hand, you can select a dryer
and drying options. Factors to discuss
include the dryer's installation and operating costs, the dryer's operation and
maintenance requirements. Pll
David Phillips is manager, marketing and
communications, at Heyl & Patterson lnc.,
Pittsburgh, a manufacturer of thermal processing systems, including rotary calciners
and dryers. For more information lrom Heyl
& Patterson lnc., call (412) 788-9810 or visit
www.heylpatterson.com.
MultiTherm's
Heat Transfer Fluids
Keep All Systems
Run your system more efficiently,
for longer periods, with less down time.
Make System Maintenance a Priority!
1-800-339-7549
www.process-heatrng.com. June
2013
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