Cooling towers are used to cool down hot condenser water taken
from chillers of air conditioning systems. The cooling effect
of cooling towers are attributed to the evaporation of the
water when it is blown through by air from the fans.
After some time of circulating through the cooling towers, the
water becomes more and more concentrated with the dissolved
salts in the water. The concentrated water has to be drained
off and fresh new water added into the system to make it less
saline.
However, when fresh water is added, it will not have any
passivation chemicals to protect the piping and the component
condenser parts from corrosion. So chemicals are added to
protect the piping and the machinery.
For cooling tower water, the chemical used serve 2 basic
functions - a corrosion inhibitor and a biocide.
The corrosion inhibitor is for preventing corrosion in the
piping and the related parts. The biocide is to prevent growth
of algae, bacteria and other micro organisms.
Every water treatment chemical company has its own formula and
special concortions. A typical corrosion inhibitor may contain
about 1 - 10% Potassium Hydroxide or similar alkali. This is
then further diluted when mixed with the water in the cooling
tower. Being an alkali, it will neutralize any acids found in
the water that can cause corrosion to occur.
The cooling tower is installed outdoors. With the ample warmth
from the chiller, fresh air and sunlight, the water it contains
is a very ideal medium for the growth of micro organism.
Micro organism growing in cooling tower water causes a lot of
problems. Clumps of algae can cause chokages in the pump
strainers. Long strands of microscopic plants can act like
nets that can cause restrictions to the flow of the water.
Some organisms cause diseases and other health related problems
to people. A typical biocide contains Sodium hypochlorite with
concentrations ranging from 10 - 20%. Again, this is further
diluted when mixed with the cooling water.
Even with the dosing of chemicals, the cooling tower needs to
be cleaned every now and then. Dusts from the air still manage
to settle down inside the sump of the cooling tower. So does
the remains of dead micro organisms. These can stick to the
infills and prevent the proper distribution of the water flow.
Sometimes cooling tower plastic infills get brittle due to the
exposure to ultraviolet rays found in sunlight. They often
break up into small particles that can choke even coarse
filters.
Folks, it's time to clean up!
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