An initial analysis on the energy-efficient performance of a natural draft wet cooling tower with CaCl2 solution for power plants

To improve the performance of the natural draft wet cooling tower, the calcium chloride (CaCl2) solution is used as the circulating water to reduce its evaporation loss. Employing a natural draft wet cooling tower of 600 MW generating unit as a reference tower, a simplified mathematical model is utilized to determine its outlet water temperature and water consumption under different working conditions. The latent heat decreases and the sensible heat increases when the heat transfer takes place in the cooling tower and the concentration of CaCl2 rises in the solution, so the evaporation loss of the circulating water decreases. Water consumption decreases with the increase in salt concentration, whereas the cooling performance becomes bad. When the salt concentration is equal to 35%, the water consumption decreases about 28%, however, the outlet water temperature increases about 8 °C. The performance and water consumption are studied under different working conditions of air parameters, water mass flow rates and tower parameters. The results indicate that the cooling performance and water-saving characteristics of the natural draft wet cooling tower can be improved comprehensively if the tower parameters are optimized.

► The CaCl2 solution is used as the circulating water to reduced evaporation loss.
► Calculations show latent heat decreases so that the evaporation loss is decreased.
► Noticeable water is saved when the salt concentration is 30%–35%.
► Increasing of outlet water temperature may be eased by optimizing the tower.