Common Misconceptions During the Designing of Cooling Towers
Some owners of manufacturing plants that need cooling towers incur unnecessary costs by asking cooling tower designers to include features that have little bearing on the effective performance of the tower. Such factory owners may be under the influence of common misconceptions about cooling tower designs. This article discusses some of the misconceptions that you should not believe when you are discussing the design of your cooling towers.
Less Drift Results in Less Water Consumption
The need to conserve water has led some people to look for all ways to save on the water consumed by cooling towers. This has led some makers of cooling towers to come up with cooling tower designs that severely limit drift (the loss of water droplets in the stream of air circulating above the cooling tower). Drift usually contains dissolved minerals. Once drift is reduced to a bare minimum, those minerals eventually precipitate and form scale on the walls of the cooling tower. That scale is usually removed by bleeding the cooling tower so that it is not damaged by the accumulated scale. Thus, controlling drift necessitates more frequent bleeding. The water you save by controlling drift is likely to be lost as you remove scale from the bottom of the cooling tower. It may therefore be inaccurate to suggest that controlling drift always results in less water consumption in the cooling tower.
Drift Control Eliminates Fog Formation
Some people also believe that the fog seen rising from a cooling tower during some months of the year is a result of excessive drift. This misconception may lead you to ask the designers of your cooling tower to find measures to limit the volume of drift in order to avoid fog formation. However, a careful observation will reveal that fog usually forms when the ambient temperature is so low that the water vapour rising from a cooling tower quickly condenses to form water droplets. In this case, the cause of the problem is the low temperature around the cooling tower and not the amount of drift emanating from the tower. Water vapour escape is necessary for cooling tower performance, so reducing it drastically would make the cooling tower be less effective because the water inside the tower would not lose heat to the air circulated by the fans inside the tower. Vapour forms when the water inside the cooling tower releases latent heat of vapourisation.
Make sure any design specifications that you insist upon have a practical role that they serve during the operation of the cooling tower. Don't be misled by the misconceptions above, and others like them. Talk to a cooling tower design expert so that he or she can give you accurate information about the best specifications for effective cooling tower performance.
