WHAT IS COOLING TOWER FOULING?

Fouling is the clogging of any surfaces or pipes with debris, dirt, and dust. Fouling is defined as a scale deposit layer such as the formation of calcium carbonate on heat transfer surfaces and occurs more rapidly when the concentrated water is circulated in the cooling towers and heat exchangers.

The economic loss due to the fouling is one of the biggest problems in all industries dealing with heat-transfer equipment. Besides, as the fouling deposited on the heat transfer surfaces reduces the cross-sectional areas of the flow passages, the flow rate of the coolant decreases, and the pressure loss of the system increases.

Impact of Cooling Tower Fouling

In cooling towers, fouling can generally be defined as a buildup of material or deposits on the heat exchange surfaces that can degrade heat exchange performance. When water cannot make it into and pass through the fill as designed, the air is not cooled properly. This means that the system must work longer to achieve the same results. Which means it is using more electricity.

Consider that for each degree that condenser supply temperature is above design specifications, chiller efficiency is reduced by two percent. This, in turn, promotes the deposit and growth which may corrode both tower fill and the tower itself, eventually requiring costly and time-consuming replacement.

Types of Fouling

Fouling can occur in different areas of your cooling tower system. There are several types of fouling that are commonly occurring in cooling towers. Here are some of the common one:

Precipitation Fouling or Scaling – These may typically be mineral-based scales that form due to exceeding the saturation point of the scaling species. The most common forms of scale are usually from calcium-based salts such as calcium sulfate or calcium carbonate. This phenomenon is strictly temperature related and is difficult to be removed by hydro-blasting or typical scrubbing. The compound created from this reaction of the free ions is called scale and the action itself is called scaling

Microbiological Fouling or Biofouling – Microbiological fouling that may occur from poor or inadequate biocide feed and control. Cooling towers by nature are places that are hot and humid. Along with the common and plentiful nutrients that most water sources contain it is an ideal place for the growth of unwanted biological growth, such as bacteria. Even very thin layers can reduce the thermal efficiency dramatically.

Particulate Fouling or Deposition (including corrosion products) – Suspended solids such as dirt or corrosion products that settle out in the cooling system. The chief causes of corrosion of metals by water are dissolved oxygen and dissolved carbon dioxide. The latter lowers the pH, permitting general acid attack but even if the water is alkaline the metal of the system can be affected by oxygen corrosion.

In addition to the reduction in water flow and heat transfer also damages the equipment and corrosion reduces the effectiveness of the work. This can lead to expensive repairs or even replacement of equipment.

SBR Technology: Combating three major ailments of Cooling Tower

Other water treatments require several separate activities and costly chemicals, which lower water quality and raise costs. SBR technology is a multi-purpose solution performs one sophisticated integrated process that is clean, inexpensive and environmentally friendly. Major Problems in cooling towers explained above are biological growth, scaling due to TDS and corrosiveness due to PH of water and under deposit corrosion in the system. These three problems are avoided by SBR in the following manner: –

Anti-Scaling: – Due to electrolysis (Cathode and Anode Reaction) all the TDS (Salts like Calcium, magnesium, Iron) are attracted to the Cathode(-) and are stuck and precipitated to the smooth surface of the Cathode Drum. As the water becomes soft the salts are dissolved and the capability of the water to dissolve the salts increases and some precipitation takes place in the drum which is automatically removed.

Anti-Corrosive:– Since the Chemicals are not added into the system there is no chance of the corrosion to take place as due to electrolysis the water becomes soft and tries to accommodate all the salts in itself and also removes the existing salts deposited in the system. So, the chances of under deposit corrosion due to scale is also avoided.

Biological Growth: – Due to anodic(+) reaction Free chlorine, Hydrogen Peroxide, Carbon Dioxide, Ozone, Oxygen is evolved which kills bacterial growth and also kills the algae in the cooling tower. Since the free chlorine is available in the water it will stop the algae growth in the cooling tower.

As a fully automatic online system, SBR technology continuously cleans the cooling tower water and augments the cooling performance, and treats cooling water without any chemicals. Solutions like SBR are ideally poised to help: In three simple steps, plants can clear fouling and restore system performance.