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Hybrid Wet Dry Cooling Tower

Hybrid Wet Dry Cooling Tower

Hybrid wet dry cooling tower systems, also known as wet/dry or hybrid towers, are often seen in power plants.

These towers are a common choice because they are built to avoid large plumes in areas such as residential neighborhoods or airports where plume visibility is undesirable. Designed to emit no plumes even in cold or humid ambient conditions, the hybrid wet dry cooling tower is a cost-effective, high-performance solution. It works by combining an evaporative cooling tower combined with a dry heat exchanger in the upper part of the structure.  

The hybrid wet dry cooling tower structure is ideal for situations where plume abatement is a priority

Whether it is due to environmental impact or aesthetic reasons, a hybrid wet dry cooling tower can be designed to minimize plumes while providing a solid, high-quality cooling tower in a variety of materials. Plume visibility is minimal when using a hybrid wet dry cooling tower with the correct configurations. They are therefore extremely desirable in residential areas as well as around airports, where visibility is of the utmost importance.  

Hybrid wet dry cooling tower systems are made up of the following components, which need regular maintenance:

  • outer shell (material: FRP, steel, stainless steel, concrete)  
  • supporting structure  
  • water basin  
  • fan stack  
  • cooling fill  
  • drift eliminators  
  • dry cooling exchangers  
  • mixing modules  
  • fan with drive  
  • water distribution system including spraying nozzles 


The materials used to make these elements may vary depending on the wetness/dryness of the area, individual preference, and local building standards. The best practices for tower maintenance will be taken into consideration when constructing plume-abated structures to ensure that proper maintenance can be carried out easily and effectively.  

Designed using the wet cooling principle, hybrid towers also contain a dry cooling module.

This reduces the water temperature and draws in the surrounding air before the water enters the wet section. The hot air from the dry cooling is mixed with saturated (wet) air to get rid of the steam plume, which would otherwise have been visible. 

The first hybrid wet dry cooling tower systems were developed in the 1960s. They are used in geothermal power plants and combine the advantages of wet and dry cooling towers. More recently, the Queensland Geothermal Energy Centre of Excellence has made several advances in the field. The researchers set out to reduce water consumption during geothermal power production, and noted that a beneficial side effect was the lack of plume. This system differs greatly from a standard wet cooling tower or a dry cooling tower. While wet cooling towers are specifically designed to evaporate water into the air that flows through the tower, dry cooling tower systems work differently in that they transfer heat from the power plant directly into the air. 

Combining two systems with an hybrid wet dry cooling tower also offers the advantage of being able to use the wet mode in isolation or choose the hybrid mode. This flexibility is perfect for varied environmental conditions. Contact Hamon if your company is running such a system and requires specialized maintenance. Generally, standard water treatment is the primary step in terms of maintenance. If this is not a viable option for your particular situation, a detailed alternate maintenance program can be planned and implemented. 

As part of regular maintenance, the heat exchange medium will be evaluated for bacterial and algae growth, with sterilization treatments to take care of the evaporative media. Finned tubes will require additional cleaning measures. Next, the fan-assisted units will need to be cleaned to prevent them from sending dirt and humid air through the fins, which can trigger corrosion. Although galvanized steel and other strong alloys are generally used in the manufacture of plume-abated cooling systems, mineral scale and dirt can still cause surfaces to deteriorate faster. This can weaken the very structural integrity of the system. Unprotected finned tubes are especially susceptible to this sort of deterioration. Luckily, regular and comprehensive maintenance programs for plume-abated cooling systems can help keep the increased risk of scale and bacteria under better control.


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