Do Closed Cooling Towers Need Frequent Water Replenishment During Operation?

 

 

Water loss in closed cooling towers mainly comes from four sources: evaporative heat loss, wind drift loss, blowdown loss, and minor system leakage. Among them, evaporation loss is the primary and unavoidable part. Closed cooling towers dissipate heat by evaporating external spray water on the coil surface.

 

During evaporation, water continuously turns into vapor and enters the air, and this volume must be compensated by water replenishment. Under normal conditions, evaporation loss accounts for approximately 1% to 2% of the circulating water flow. Higher load, higher ambient temperature, and lower humidity lead to greater evaporation and correspondingly higher water demand.

 

 

The second is wind drift loss. The top of a closed cooling tower is equipped with a fan that generates upward airflow during operation, which carries fine water droplets out of the tower, causing water loss. High-quality closed cooling towers are equipped with water eliminators and baffles to effectively reduce drift loss, which can generally be controlled within 0.1% of the circulating water flow. Aging, damage, or improper installation of water eliminators will significantly increase drift loss and raise the frequency of water replenishment.

 

 

 

 

 

The third part is blowdown loss, also known as blowdown flow. To prevent the concentration of calcium and magnesium ions in circulating water after repeated evaporation, which causes scaling, corrosion, and microbial growth, the system requires regular blowdown to discharge high-concentration wastewater and replenish fresh water. Blowdown volume is determined by the cycles of concentration; higher cycles mean less blowdown and less water replenishment. Proper water treatment and automatic blowdown control can significantly reduce unnecessary water replenishment.

 

 

 

Finally, system leakage loss mainly involves minor seepage from spray pipe joints, water basins, valves, flanges, and other components, which is normally minimal. However, if cracks appear in the water basin, seals age, or pipelines break, leakage will increase noticeably, resulting in frequent water replenishment and requiring timely maintenance.

 

 

 

 

 

In summary, closed cooling towers do need continuous small-volume water replenishment during continuous operation, while intermittent operation only requires one refill at startup. Water consumption is relatively high during high-temperature, full-load summer conditions and decreases significantly under low-load winter conditions. Short-term severe water shortage requiring frequent replenishment is usually abnormal, often caused by damaged water eliminators, improperly closed blowdown valves, leaking water basins, or broken pipelines.

 

 

 

 

 

In daily operation, measures such as increasing cycles of concentration, installing automatic makeup valves, regularly inspecting sealing structures, and promptly repairing leaks can effectively control water consumption. Overall, closed cooling towers have lower water loss and better water-saving performance than open cooling towers. With proper maintenance, they do not require excessive manual water replenishment, and automatic water supply devices can sufficiently support stable operation.