The Basics Of Scaling And Fouling In Industrial Cooling Towers

A cooling tower is an integral component of any milk processing plant. Various factors can limit the efficiency of a cooling tower in your facility. Scaling and fouling are among the most common of these factors.

As you set up your first dairy processing plant, it's important to understand the two problems, how they'll affect cooling tower operations and the steps that you can take to prevent the mentioned problems. Below is a discussion on the same.

What They Are

Scaling is a process through which dissolved mineral salts accumulate on various surfaces of a cooling tower. Common mineral deposits responsible for scaling include magnesium silicate, calcium carbonate and calcium phosphate. The solubility of these salts in water decreases as temperatures increases within a cooling tower.

Fouling is the process through which suspended particles (foulants) in the water that runs through the tower are deposited on the tower's surfaces. Foulants that are common for this problem include silt grease and oil and various forms of organic matter.

Scaling and fouling are similar in the sense that they create an insulating barrier on cooling tower surfaces. This barrier limits the ability of the tower to exchange heat effectively, resulting in significant energy losses. Fouling on the tower's fill material also reduces the surface area available for heat exchange within the system.

The Question Of Water Quality

Poor water quality is among the most common factors responsible for scaling and fouling. The water that your cooling tower will use is likely to be surface water, groundwater, or re-used/recycled water.

Surface water is often sourced from streams, rivers and lakes.  The mineral composition of surface water might vary from time to time. Therefore, surface water can have higher concentrations of the compounds responsible for fouling (silt and debris) and scaling (magnesium and calcium salts).

The composition of groundwater is less vulnerable to seasonal variations. Depending on the geographical location of the groundwater source, such water might be inherently rich in the mineral salts responsible for scale formation.

The composition of re-used/recycled water largely depends on the quality of treatment that the supplier subjects the water to.

How Scaling And Fouling Can Be Prevented

To reduce the likelihood of scaling, avoid using hard water for cooling tower operations. If this will not be entirely possible, consider introducing chemical additives in the water. These additives are known as mineral stabilisers, and they react with calcium and magnesium salts to form soluble compounds that won't be deposited within the tower.

Fouling may also occur when silt and debris is introduced into the tower through leakages or through cracks and crevices. Regular inspection of the tower (and timely repairs) for such defects should help to keep foulants at bay.