Efficiency of water usage in cooling towers can be measured by the amount of times water can be cycled through the system. This is also known as cycles of concentration. As pure water evaporates from the cooling tower, the dissolved solids in the water remain behind and steadily increase in concentration. The ratio of the concentration of dissolved solids in the cooling tower water to the concentration of dissolved solids in the make-up water is used to measure the cycles of concentration.
Make-up water can be described as the water used to compensate for the loss of water through evaporation and system bleed. The composition of the make-up water determines how many cycles of concentration may be attained in a cooling tower. When the pH and calcium of the make-up water is too high, the number of cycles of concentration is limited by the solubility and possible precipitation of scale.
Water and sewer savings are significantly higher at maximized cycles of concentration. If make-up water is limiting your system to less than 3 cycles, feeding acid may provide a more economical operation for your cooling tower.
What does the acid do to the tower water?
Adding acid to the cooling tower water balances pH and prevents scale from forming.
More specifically, adding acid will neutralize alkalinity. Sulfuric acid reacts with natural carbonate alkalinity in the water forming carbon dioxide (which is dispelled to the atmosphere) and an all-natural compound called sulfate.
How do I calculate how much acid I will need?
The amount of acid required depends on the alkalinity of your make-up water and your desired cycles of concentration. You will need to add enough acid to neutralize the alkalinity to a point where the calcium hardness remains soluble. This will require you to consider what the alkalinity will be once the make-up water has cycled up and after the acid is added.
It is important to understand how alkalinity is “cycled up” in systems and it is dependent on many factors that will vary from water source to water source. To safely calculate the need for an acid supplement, do not hesitate to call a member of the Chardon Technical Support Staff.