A. Application of cooling towers

As a result of various industrial processes, waste heat is produced, which in many cases cannot be exploited economically, so that it has to be emitted to the environment. With heat transfer to rivers or lake water, very low temperatures can be achieved -and this results in high efficiency for thermal processes. At many locations, the limits of ecological capacity have already been achieved or the required quantity of water is not available. In these cases cooling towers may be used advantageously in order to transfer the waste heat to the atmosphere. For this purpose, the type of cooling tower is selected according to its application.

For the cooling of condensers for steam turbine plants, direct cooling with, say, fresh river water is preferable for economical reasons. The enormous quantity of water, which is returned to the river with higher temperature, can have a disturbing effect on the environment. In order not to stretch the heat balance of rivers too much, the cooling water can be cooled in a wet-cooling tower before it is returned into the river again. If the required quantity of fresh water is not available recycle operation of the cooling tower can be chosen. Then, only the water losses due to evaporation and blow down must be replaced. For base load power stations, mainly natural draft cooling towers are applied for the supply of constant load.

Most cooling towers are less noticeable because of their smaller dimension. These smaller units are applied in a wide range of technologies such as in refrigeration, plastic processing, food technology, plant engineering, steel industry, paper technology or petro-chemicals. For each application, specific duties must be considered in order to provide safe operation of the cooling tower. The selection of appropriate components and cooling tower type is based on the experience of both operator and manufacturer. One common feature is the flexible use of mechanical draft cooling towers.

B. Types of cooling towers