POWER March 2017 - 28

WATER & WASTEWATER
Cooling Towers: Efficiency
Waiting to Happen
Courtesy: GE Water & Process Technologies
Cooling towers serve the vital role of cooling water for power plant heat exchange
equipment. Sustaining excellent system performance is important because a onedegree
increase in water temperature can cause a 2% increase in energy usage.
Proper maintenance and a few upgrades could improve a cooling tower's efficiency,
while also saving water in the process.
Abby L. Harvey
T
he smallest inefficacy in a power plant
can cost a generator greatly, and many
energy generators need to look no further
than their aging cooling towers to find a
hotbed of potential inefficacies, slowly leaching
their profits. As the efficiency of a cooling
tower stumbles, the temperature in the
tower rises, increasing energy consumption
in the unit by as much as 2% per one-degree
increase. The good news is, from the fans to
the nozzles, to the fill media, and even the
water itself, opportunities to ramp up the efficiency
of a cooling tower abound.
Film Fill for the Win
Of course, nobody intends to build an inefficient
system, but many of today's cooling
towers are relics of the past, and while they
may have once been state-of-the-art, they fall
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far behind today's standards. One of the main
areas that older plants lag behind in is fill
material. Some decades-old cooling towers
still in use continue to use plastic, fiberglass,
or wood splash fill. This system positions
splash bars to break falling water into droplets.
Splash fill is better suited for crossflow
towers, according to SPX Cooling Technologies
Inc., because the air can easily flow
horizontally through the vertical full-height
fill. Newer counter-flow towers can integrate
splash fill or newer film fill systems.
Around the 1980s, cooling tower efficiency
efforts got a boost with the development of
better performing fill media. " A breakthrough
for the counterflow fills of the 1980s was the
introduction of PVC film fill packs, " Terry
Dwyer, director of field erected products for
SPX, said. These new fill types " increase the
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surface area of the fill in a given cubic foot
of the cooling tower, so the PVC-the plastic
fill packs-increase the surface area, which
increases the heat transfer. "
In fact, according to Dwyer, the easiest
way to increase a cooling tower's efficiency
quickly is to change out the fill media. " We
have other, higher performing fills today than
we had many years ago, " Dwyer said. " It's
kind of like with a car, the fuel economy of
a car today is better than it was 20 years ago.
A lot of that is the engine design and technology. "
Today's
high-performance film fills boast
nearly twice the thermal performance of
splash fill. Film fill consists of stacks of labyrinth-like
material through which the water
and air flow in opposite directions. Film fill
increased greatly the exposure of the water
POWER | March 2017
http://www.powermag.com
POWER March 2017

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