Know the Type of Fouling Occurred In Your Condenser

Posted by: Powermaster Engineers Pvt. Ltd. on: March 10, 2016

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Fouling in condenser tubes is highly unfavorable as it reduces the efficiency of the firm. We have to choose our cleaning methods based on the type of fouling occurred in the tubes. Here under, the major types of fouling are detailed.

Particulate fouling:

• As the water flows through the tubes, there are good chances that the lighter particles can settle at the bottom of the tube. This debris can be algae, river silt or coal dust.
• Optimizing the flow rates through the condenser tubes can prevent the debris formation to some extent. A flow rate of 7 feet per minute would be ideal.
• The debris formation can lead to under deposit corrosion which is a serious concern. The heat transfer efficiency doesn’t fall significantly as the amount of surface, which stimulates the under deposit corrosion is less.

Scaling:

• In the cooling process of water, if the saturation point of dissolved particles exceed, a direct precipitation on the tube surfaces takes place.
• Phosphates and carbonates of calcium are the popular precipitates. Such precipitates are formed in high temperatures conditions. If the tube surface is hotter, there rate of precipitation raises.
• The scale formation isn’t confined to a small area. It covers a vast tube surface area. Irrespective of the thickness of the scales formed, it has a drastic effect on the heat transfer of the tube.
• Apart from decreasing the output from the firm, it also promotes under scale corrosion. The scales have to be removed mechanically by using tube cleaners.

Microbiological fouling:

• This type of fouling is witnessed in applications, where the water isn’t treated before feeding to the system. The presence of bacteria in the natural water causes this type of fouling.
• Treating the re-circulated water using chlorine, bleach or other biocides can prevent this fouling. It is to be noted that these biocides are of no importance when the bio-film gains a foothold.
• Altering the flow rates is another technique to stop microbiological fouling. Higher the flow rate, lower will be the chances of fouling.
• The bio-films are capable of retarding the heat transfer rates. A small amount of water gets entrapped in the films.
• Certain types of bacteria are capable of developing corrosive byproducts like sulfate reducing bacteria. Such byproducts consume the base metal weakening the tubes.

Macro fouling:

• This type of fouling is caused when the water flow at the tube inlet is obstructed by particles of size close to tube diameter.
• The particles, which result in macro-fouling are aquatic animals, windblown debris, chunks of ash, rocks cooling tower materials, etc.
• Macro fouling decreases the flow rate of water, creating favorable environment for the particles to accumulate and settle.

Numerous techniques are developed over the years to save the condenser tubes from fouling. Using screens, settling ponds and filtration systems can resist the debris inflow through some extent. Scheduling cleaning operations regularly can increase the life of the tubes. Various types of tube cleaners like plastic scrapers, brushes, sponge balls are used in the cleaning process.

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