Chart for estimating cooling tower makeup requirements

Retention time is important as it affects the time a slug treatment will remain in the system. Lower bleed-off causes longer retention times. 

The chemical composition of the cooling water makeup supply used in the plant determines the choice of the cycles of concentration. Some of the important constituents that must be controlled in the tower are calcium, magnesium, silica, carbonate, bicarbonate and sulfate ions. Alkalinity levels are regulated by the addition of acid or alkali to achieve the desired pH. When adding H2S04 (sulfuric acid) for pH control, it should be assured that calcium sulfate solubility limits are not exceeded (see Chapter 8). 

The water consumption of a cooling tower depends not only on the heat load but also on the ratio of the amounts of heat carried off by increasing the temperature of the air through evaporation of the water. The amount of 

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Figure 6.14 Chart for estimating cooling tower makeup requirements.

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