Cooling Towers

"A build-up of solid contaminants in cooling tower systems can increase the “fouling factor” and significantly increase energy consumption."

A build-up of solid contaminants in cooling tower systems can increase the “fouling factor” and significantly increase energy consumption. It has been shown that a 0.025 mm of fouling equates to a 10% reduction in cooling tower efficiencies. 

We have seen that solids accumulation in the basin can achieve growth rates of 50 to 100 g/m2/day, if calculated results in tons of solids captured in your cooling tower system. If this is effectively removed without stopping the process, the benefits outweigh the capital and running cost in the very short term.

It is because of this huge challenge that Nanotech developed the “Janitor” system to remove contaminants and reduce the cost of chemical programmes.

Incorporating an efficient on-line filtration system as in a cooling tower can extend the life of the cooling tower system, including associated pipe work, chiller plants, plate heat exchangers, and will ultimately lower maintenance costs while improving cooling efficiencies, thereby providing a significant return.

Inside clean Cooling Tower

Why keep the cooling tower basin clean?

  • Improves cooling system efficiencies: Solid contaminants can also clog small spray nozzle orifices, causing poor distribution of water throughout the cooling tower water distribution system. Filtration minimizes deposits on heat transfer surfaces, prevents heat exchanger clogging and maintains efficient cooling water distribution.
  • Increases life of the entire cooling tower system. Solid contaminants in the cooling tower system reduces the ability of treatment chemicals such as corrosion inhibitors or oxidizers/biocides to reach the surface of the cooling tower basin, pipe work and heat transfer vessels. Filtered water prevents solid contaminants from building up in the cooling tower system.
  • Reduces maintenance: A layer of solid contaminants will eventually need to be removed from the cold-water basin. Filtering the cooling tower water will minimize the need for manual cleanings (including cleaning of chiller plants and plate heat exchangers) which can result in extended downtime and significant costs.
  • Reduces downtime. In an efficient water filtration system, it can reduce system downtime for cleaning by more than 80 per cent.

To summarise, a well-designed cooling tower maintenance system using the technology concept of an on-line filtration system will lead to:

  • Savings in energy, water and money spent on labour
  • Turbidity reduction from 17 to 2 Ntu in a few days
  • Increased thermal performance of process
  • Solids suspended in basin for effective removal
  • Reduced biofouling and the risk of Legionnaires disease
  • Elimination of manual basin cleaning
  • No toxic sludge build-up in tower
  • Reduced blow down cycles and waste
  • Minimised maintenance and downtime
  • Reduced under-deposit corrosion
  • Increased life cycle of tower chemicals
  • Effective and optimised water treatment programmes
  • Sludge recovery option for minimised effluent
  • Environmentally friendly
  • Maximised lifetime of equipment

Where does the contamination come from?

Three primary sources are responsible for the most common cooling tower contaminants:

  • Ambient air dirt load, including windblown sand, soot and all types of organic debris. Cooling towers make excellent air scrubbers.  Relatively high volumes of air pass through cooling towers and most of the contaminants in the air end up in the cooling tower basin.
  • Circulation water build-up:  Calcium carbonate scale that forms in the cooling tower system will eventually flake off. Treatment chemical residue and algae also can build up in the circulation water.
  • Makeup water: Depending on the source and water quality, the makeup water can significantly contribute to contaminant build-up.

Where cooling towers with on-line filtration systems are installed, the water is cleaned, and its particle load condition stabilizes in a short amount of time (typically two to three days). In areas where debris is more prevalent, the side-stream amount can be increased to handle the higher particulate load. In severe cases, a full-stream system can also be implemented.

Nanotech can custom design a system based on the application and your requirement. Contact us for a consultation on how we can implement these benefits for you.