Chemical Engineering June 2010 - 17

Air Products
Newsfront
Cool It!
Figure 1. Cryogenic cooling
is suitable for processes such as
refrigeration and size reduction.
These photos depict equipment
using N2 for food processing and
particle reduction
Whether it's cooling towers or industrial
gases, experts say embracing new
technologies makes it possible to get
more bang for your cooling buck.
Cooling technologies
Currently, the fleet of cooling towers
in the chemical process industries
(CPI) is fairly old and a large number
of them are approaching the end
of their design life, says Paul Lindahl,
director of market development with
SPX Thermal Equipment and Services
(Charlotte, N.C.). " This means
the towers now require more frequent
inspections and more work to keep
them structurally fit, so many owners
are evaluating whether or not to
replace them, " he says.
Though capital is tight, replacing
an aging cooling tower with one that
conserves water, energy or both, just
might make good fiscal sense in resource
cost savings, say the experts.
Hybrid cooling towers are a suitable
replacement for traditional
equipment when the goal is to reduce
water and energy consumption. Most
traditional cooling towers run water
across a fill material and then blow
air across it to provide cooled process
water, which is both water and energy
intensive. Hybrid fluid coolers, on the
other hand, employ a design that can
provide leaving-water temperatures
in ranges similar to temperatures
achieved with conventional evaporative
cooling tower systems, while reducing
energy and water use, cutting
operating costs and providing clean
water for a process.
New process cooling technologies
make water and capital conservation possible
for chemical processors
Ill.) offers
Hybrid Fluid Coolers, featuring an
adiabatic design, which operate as airto-water
heat exchangers and use a
number of variable speed fans as dictated
by process cooling requirements,
says Tom Benson, vice president of
sales and marketing.
During much of the year and in
warm weather climates, hybrid coolers
can provide 85°F exit water temperatures.
In cooler climates, leavingwater
temperatures as cool as 46°F
are possible without using glycol.
And, the units do this while saving
big on energy and water consumption.
On hot weather days, the relative humidity
of ambient air is increased by
spraying an atomized fine mist of city
water into the incoming air stream on
both sides of the unit. The adiabatic
system decreases the air temperature
as it enters the unit and results in
lower exit water temperatures compared
to those achieved by a cooling
tower alone.
Users can run process water temperatures
low enough using only a hybrid
fluid cooler so that it might be possible
to operate equipment without the use
of additional,
bonus, process water is kept clean and
uncontaminated without the need to
treat for water scale or bacteria.
Frigel (East Dundee, Ill.) offers a
similar piece of equipment, called
the Ecodry system, which the company
touts as Intelligent Process
Cooling - a system that uses ambient
air to cool clean process water
and offer flexibility.
What makes the Ecodry systems
smart begins with a close-circuit fluid
cooler, in place of a traditional cooling
tower. The water returning from the
process is pumped into heat exchangers
and cooled with ambient airflow.
This process provides clean water at
the right temperature to process machines
year round.
central-chilling units.
And, since the hybrid fluid coolers are
closed loop, there is no need to replace
evaporated process water, which uses
less water for process cooling than a
conventional evaporative cooling tower
system and conserves water. As a
Ecodry can also be used in conjunction
with the company's Microgel
(chiller/TCU combo) or Turbogel
(TCU) to serve as an alternative to a
central chilling system and provide
temperature control at each machine.
In this case, a single set of uninsulated
pipes supplies the process water, without
heat gain, to a Microgel or Turbogel
on each machine. These units offer
high flow, precise temperature control
and a built-in free cooling valve that
provides automatic free-cooling when
ambient temperatures are lower than
the process set point. By controlling
flow and temperature at the point of
use, energy is conserved.
Another method of reducing coolingChemiCal
engineering www.Che.Com June 2010 17
Thermal Care (Niles,
Just Cool It!
L
ike other aspects of chemical processing,
cooling operations are
being closely examined for ways to
reduce costs and resource usage.
http://www.Che.Com
Chemical Engineering June 2010

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