Our goal for all Watertech customers is to maintain efficient and reliable
water management programs. These programs create systems that not only use less
water, chemicals, and energy but experience far fewer failures and periods of
downtime, extend equipment life and reduce liability due to human illness
caused by waterborne pathogens.
To achieve this goal,
you need more than just the right feed and control equipment or monitoring
technology. Working side by side with a water treatment partner, you can
develop a custom plan that ensures your system is set up to run in an optimal
way.
Following are the top
three ways facilities can immediately reduce operating costs in cooling
systems.
1. Keep heat exchangers
free of build-up
A well-designed chemical
treatment program that includes antiscalants, corrosion inhibitors, and
disinfectant chemicals — as well as regular cleanings — will keep heat transfer
components free of scale, corrosion, and biofilms. Scaling and biofilms act as
an insulator, requiring more energy for the chiller to cool water to its
desired temperature. The chart below illustrates how quickly costs can escalate
because of scale formation on a chiller evaporator.



Condenser side of a chiller: Clean vs. Scaled.


Cooling tower fill: Clean vs. Scaled
2. Maximize cycles of
concentration
It is a common practice
to bleed cooling tower water before the concentration of dissolved solids
reaches a level where scaling or corrosion could occur. Bleeding the tower
water at the proper rate is critical for cost efficient operation. Too much
bleed will increase costs related to water and chemical use while too little
bleed will result in scale deposition and/or corrosion. Consult your water
treatment partner to determine the most effective ways for your facility to
increase cycles of concentration of recirculating cooling water.
In some industries,
cooling water systems can account for up to 80 percent of a facility’s water
use. There is tremendous potential for water savings that converts directly to
dollars saved to your bottom line.
Some best practices
include:
- Automating chemical feed and tower bleed
- Softening the makeup water
- Feeding acid to control alkalinity and pH
- Looking for a better quality make-up water
- Installing side-stream filtration for solids removal
The following Watertech
customer increased from 3 cycles to 5 cycles of concentration on their 900-ton
cooling tower. The result: they cut their water bill by 62 percent. Total
savings (including reduced chemical and other related costs) was upwards of
$27,000.
3. Use the minimum
effective dosage of chemicals
Proper dosing of
chemicals is critical for cost efficient operation of an open recirculating
cooling water system. Overfeed is an expensive waste of chemical and can in
many instances cause issues with sludge buildup, corrosion, and environmental
discharge problems. On the other hand, an underfeed will result in scale
formation, corrosion, and microbiological growth issues.
Below are three
scenarios where customers commonly overfeed chemicals.
Scenario 1: Soft water
versus hard water makeup
Makeup water quality for
cooling water systems varies tremendously from system to system. Those systems
that have good quality makeup water can use lower doses of the chemical to
maintain clean heat transfer surfaces than those using high hardness, high
dissolved solids levels. It is common for those systems with good quality
makeup water to use half the volume of chemical. Be sure you are feeding the
minimum effective dosage and properly controlling the concentration in the
tower water.
Scenario 2: Summer
versus winter chemical dosage
Cooling tower water is
generally warmer during the summer months than in the winter months, especially
in the northern half of the country. Because of this, bacteria, mold, and
fungus show a higher growth rate in warmer months and may require a higher
dosage of biocide for proper control. Be sure to change your biocide program
during the winter months to reduce costs.
Scenario 3: Use accurate
test methods
Accurate water testing
methods are crucial for determining the effective minimum dosage of chemicals.
This means utilizing high-quality technology you know you can rely on. While
drop count kits and titration based test kits were the method of choice for determining
inhibitor concentrations, new fluorescent tracers allow for much more precise
measurement of inhibitor concentrations in cooling water. Both drop count and
titration test kits are prone to interferences caused by the high mineral
content in tower water. When these interferences occur they commonly show a
false negative, meaning the concentration of the inhibitor in the tower water
is actually higher than what the test shows. The newly traced inhibitors show
very few interferences and very high accuracy even at dosages in the
parts-per-billion range. Watertech customers have experienced 40 to 60 percent
savings in chemical costs using these traced inhibitors when compared to the
older technology.
If you would like more information on having a more streamlined and cost-contained program, reach out to Watertech of America for a free site survey.