Cooling Towers and
A range of packaged systems is available, from small,
manually operated, to larger, 'Spec' built fully automatic systems with
remote control and data logging.
Since ozone is an unstable oxygen molecule that cannot be stored or
shipped, it must be generated on-site at the point of use. Problems
associated with the ordering, shipping, handling, storing, record logging,
and effluent disposal of standard water treatment chemicals are thus
eliminated. The discharge water from an ozonated cooling tower will comply
with current U.S. EPA and South African regulations.
Bacteria present in cooling tower water intensify
scaling by forming a bio-slime layer that acts as a bonding agent for
scale deposits and can harbour and proliferate Legionnaire's disease and
other pathogens. Because ozone is a very strong biocide it destroys the
bacteria, leaving the scale deposits free to be removed by the velocity of
the water through the pipeline.
Years ago, the chromate/zinc inhibitor was one of
the best inhibitors on the market to protect metal surfaces from corrosion
in a cooling tower. Today, ozone is attaining the same recognition by
providing the same or better corrosion protection than the old
chromate/zinc inhibitor. Ozone provides a protective oxide coating on the
metal surfaces within the condenser loop.
Ozone reduces operating costs by
Reducing makeup water to the cooling
towers by permitting more cycles between blowdowns.
Eliminating the cost and problems in
ordering, shipping, handling, storage, and disposal of regular chemicals.
Reducing power consumption by keeping
the chiller heat transfer efficiency high through cleaner condenser tubes.
Ozone systems must be sized
individually. Our application specialists will review and utilize your
existing equipment (such as aeration towers, pumps, filters and buildings)
to be fitted for the new purpose. Manual and fully automatic systems are
available. The reason for selecting either one can be purely economical.
A. MANUAL SYSTEMS
The manual systems require almost the same level of attention as the
systems with chemical feed. In manual systems OZONE simply replaces
biocides, with the following advantages:
Eliminates the use of chemicals except
for pH balancing.
Ends discharge liabilities and
chemical storage record keeping.
Destroys all types of micro-organisms
like Legionnaire's disease etc.
Minimizes condenser fouling.
Decomposes organic waste by oxidation.
Prevents calcium carbonate scaling.
Removes existing calcium carbonate
scale by destroying the biomass glue bonding agent.
Reduces the corrosion rate of metals,
including copper heat exchangers.
Prevents delignification of wood frame
Reduces water consumption by
maintaining higher cycles of concentration in the cooling tower.
Saves on energy costs by increasing
the heat transfer efficiency of the chiller.
The operation is
Start with full ozone production to
achieve the fastest initial cleanup.
When the water and all surfaces are
clean, and all fallen scale has been removed, read the corrosion coupons.
If the corrosion rate is high, use a PDP or ORP test to measure ozone
residual. Record the corrosion, ozone residual, ambient temperature and
pH, into your logbook. Reduce the ozone production by 20%.
Repeat once a week, until you obtain a
pattern that is characteristic for your specific climatic conditions,
cooling tower design, and makeup water characteristics.
Often the cooling towers already have
automatic blow down installed — the new ozone treatment will not
interfere. Elevated ambient temperatures require more ozone. If the tower
was off-duty for a long time, or neglected, about one litre of hydrogen
peroxide will dramatically speed up the initial cleanup without adding any
chemicals to the discharge.
Manual systems are available for smaller
towers where the additional cost for an automation system may not be
justified. Ozone will still provide the great advantages listed above.
B. AUTOMATIC SYSTEMS
In automatic systems the corrosion, dissolved ozone, pH, conductivity, and
AC current are measured in 0.5 second periods, and the ozone dosage is
adjusted automatically. Data logging is also automatic, and easy to access
from any telephone line via proprietary software. By precisely following
the optimal pattern, the corrosion rate is very low in the first year and
almost below detectable level in the years following.
The heat exchangers are usually 10 times more
expensive than an automatic ozone system of matching size.
The automatic system will extend the life span of the heat exchanger, and
of other metal surfaces, by at least a factor of 10.
Usually the initial investment for an ozonation system will return in just
six months! A phone line access can also provide data for
preventive maintenance, and security purposes.
The automatic system also allows for a more accurate blow down. The
discharge water is very clean, and safe for accidental drinking.
C. MAKEUP WATER SYSTEMS
The makeup water should always meet the drinking
water quality standards. In other words, a cooling tower is not a dumpsite
for sewer or otherwise bad water.
Ozonation systems are available to
treat makeup water to drinking water quality standards. Ozone is also very
suitable to treat surface water sources. Surface waters are mostly very
soft, thus ideal for use in cooling towers. We will calculate the proper
makeup system based on your raw water test results.