The cooling systems use the air to reduce the cooling water
temperature. The air against the water flow "steals" the heat and gets
rid of the solid particles, oily residues and bacteria. The particles retained
by the droplets add to the contaminating elements in water, and the more serious
are due to: deposits, scale and corrosion.
Originated from the suspension solids, from the system corrosion products, or a
result of live organism metabolism. Many times, the corrosion products are
joined to particles originated in the air to form bulky deposits which reduce
the water flow. The deposits of microbial origin grows quickly, distinguished by
bulky volumes and low density. Those are very dangerous as being "habitat"
to bacteria colonies development. After a certain thickness, and depending on
the "Dead Zones" of the tower, they become inaccessible to the
biocides, arising conditions to create resistance in the new bacteria
Originated within the deposits that lose water of hydration. The most common
are of calcium carbonate and emerge mixed to the products of corrosion,
particularly with iron oxide. When the scale shelter microbiological
colonies, they present typical formations known as tubercles or alveolus. Under
these develops corrosion due to acids of the bacterial metabolism. Scaling not only reduces heat transfer as well as
is responsible for
generalized corrosion or for "pitting".
In synthesis, corresponds to the passage of iron to the stage of superior
oxidation and, therefore, its withdrawal from the carbon-alloy. This process not
only reduces the line thickness as well as the wall resistance. The destruction
of the line is spontaneously processed within the alkaline and neutral media
forming ferrous hydroxide, ferric hydroxide and magnetite. The ferrous hydroxide,
is greenish-black and occurs within alkaline media and aired waters. The ferric
Fe (OH)3, is reddish-orange and is formed in neutral media. The Magnetite,
Fe3 O4, is a black and magnetic compound, formed in
the absence of air. The ferrous hydroxide and the ferric hydroxide are
bulky and mixed to residues of biological metabolism and solid particles which agglutinate
forming adherent mud. Therefore the water and contaminants should be strictly
controlled in order to prevent the systems destruction.