02/09/2023
Scaling in cooling water systems can be prevented using four basic approaches:
1. Limit the concentration of critical ions by maintaining concentrations that are lower than those required to cause scaling. This can be accomplished by pretreatment of the water or by limiting the tower cycles of concentration.
2. Reduce alkalinity with acid. This removes carbonate and bicarbonate by converting them to CO2. Since the carbonate level is controlled, the potential for calcium carbonate is restricted.
3. Alter system design or operation. Scaling potential can be altered by altering the system’s mechanical operation. Options include:
*** Increasing cooling water velocity, which keeps the water cooler
*** Using compressed air to “air rumble” the heat exchanger inlet water on a periodic basis to dislodge and remove scales and deposits
*** Modifying the exchanger design so that the cooling water is on the tube side, promoting higher velocity
*** Changing the metallurgy of the heat transfer surface. Mild steel heat transfer surfaces will scale under conditions where copper and other alloys will not, due to corrosion and surface roughness
*** Reducing the heat flux, either by reducing the process load or by increasing heat exchanger size and, as a result, reducing metal surface temperature and bulk water temperature.
4. Apply chemical deposit inhibitors. There are several types that act in distinctly different ways to control deposits.
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