Chemical Engineering July 2013 - 20

BWA Water Additives
Newsfront
COOLING-TOWER WATER:
A HYBRID PROBLEM
CALLS FOR A
HYBRID SOLUTION
In addition to the usual woes,
new issues are creating a situation
that calls for a hybrid approach to water treatment
S
caling, fouling and corrosion have
long been the enemy of coolingtower
water. While these issues
still present significant watertreatment
hurdles, today's processors
are also dealing with " impaired " water
streams and increasing restrictions
affecting intake and discharge water,
among other challenges. This one-two
punch has necessitated a hybrid approach
- one that includes both advanced
chemistries and modern, automated
equipment - to cooling-tower
water treatment (Figure 1).
Classic treatment objectives
Cooling-tower water treatment is an
integral part of operations for processors
because productivity and product
quality can be adversely affected by
scale, corrosion, fouling and microbiological
contamination. These watertreatment
problems can be very costly
when they lead to the loss of heat
transfer in the cooling tower, equipment
failure, and health and safety
concerns, according to Narasimha Rao,
vice president, R&D and Automation,
with Nalco Co. (Naperville, Ill.; www.
nalco.com).
For this reason, delicately balanced
chemistries are used to prevent scale,
fouling and corrosion in cooling tower
water. " A good water treatment company
will create a tailored program to
help processors tackle the particular
issues that apply to the local stream
of make-up water, " says Tom Falsey,
senior vice president of corporate sales
with C.C.I. Chemical Corp. (Vernon,
Calif.; www.ccichemical.com). " Every
program will differ because make-up
water will differ based on where it
comes from, the region in which the facility
is located, and factors such as the
alkalinity, hardness, and other characteristics
of the water. "
Usually, a robust treatment program
will include a balanced chemistry
containing one or more biocides,
algaecides, biodispersants, corrosion
and scale inhibitors,
anti-scalants,
and cleaners.
Today's treatment objectives
As if finding the proper chemistry balance
were not tricky enough, a recent
set of water-related issues complicate
matters further. The scarcity of water
in many places and the tightening of
discharge permits are among some of
the reasons processors need to optimize
water use. Additional factors include
the anticipated U.S. Environmental
Protection Agency (EPA; Washington,
D.C.) regulation surrounding coolingtower
intake water. Section 316(b)
of the Clean Water Act will require
that the location, design, construction
and capacity of cooling-water intake
structures reflect the best technology
available for minimizing adverse environmental
impact. " These anticipated
regulations will force processors to either
install equipment that will reduce
fish entrainment at the intake or draw
20 CHEMICAL ENGINEERING WWW.CHE.COM JULY 2013
their cooling tower water from elsewhere, "
says Kaveh Someah, global
director, oil-and-gas and refining and
petrochemical industries with Ovivo
USA (Salt Lake City, Utah; www.ovivowater.com).
" For
these and other reasons, it's not
unusual to see a cooling system with
multiple sources of water blended together
in varying ratios being used
as cooling tower makeup water, " says
Eric Thungstrom, global cooling product
manager, water and process technologies,
with GE Power & Water (Trevose,
Pa.; www.ge-energy.com). " This
can lead to variable water quality, and
if a treatment program is designed
around a projected water quality, but
if that water quality is more variable
than what was projected, it may put
additional stress on the treatment
program and cause performance issues,
such as corrosion or scaling. "
FIGURE 1. Processors are faced with
the traditional cooling-tower water-treatment
issues, as well as new problems related
to water scarcity and intake and discharge
restrictions, which require a new
approach to water-treatment programs
BWA Water Additives
FIGURE 2. Here, BWA scientists are
developing biodegradable, high-performance
antiscalants for water treatment
http://www.ccichemical.com http://www.ovi http://www.vowater.com http://www.nalco.com http://www.ge-energy.com http://WWW.CHE.COM
Chemical Engineering July 2013

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