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Products and Solutions - Natural Draft Cooling Towers



GEA Natural Draft Cooling Towers

GEA Natural draft wet cooling towers have been used to cool water, primarily in energy production, for almost 100 year. The tower operates on the stack effect which causes the hot air in the tower to rise (natural draft). The necessary stack can be designed in various ways. For both technical and cost reasons, reinforced concrete structures have become standard to handle the high cooling water flow rates from increasingly large power generating units. GEA has, in the last 50 years, constructed natural draft cooling towers for a variety of applications with water flow rates of up to 216,000 t/h.


Areas of application

Especially for power plants and industries with unlimited cooling water flow. The largest cooling water flow in a single natural draft-cooling tower built by GEA to date, has a cooling water flow quantity of 216,000 m³/h.


Key features

  • The required air stream volume for cooling is exclusively produced by the stack effect. The unique economic advantage of natural draft cooling towers lies in their very low electric energy requirement. The operating costs are minimal.
  • Economical for high cooling loads and depreciation over a long period.
  • The great distance between the air inlet and the air outlet of the cooling tower dependably avoids any recirculation of warm air that could lead to reduced performance.
  • The almost complete lack of moving parts allows for high operating reliability and minimal maintenance requirements.
  • Because of the height of the warm air outlet point the surrounding area remains untroubled by effects of the cooling system.

Cold-water temperature in comparison to cell cooling towers

The cooling air flow volume from natural draft cooling towers is directly dependant on local conditions like air temperature and barometric pressure. In cell cooling towers the air volume stream is created by fans and constant. Thus , varying local conditions create varying cool tower characteristics. Below the design point, a natural draft cooling tower offers more favorable cold water temperatures than a cell cooling tower and vice versa.


Winter operation of a natural draft cooling tower

In contrast to a mechanical draft-cooling tower, the cooling air stream volume in a natural draft-cooling tower is not directly controllable. For winter operation, dependent on the outside temperature and the thermal load, the following control elements can be deployed: zone control, i.e. disconnecting individual cooling zones and winter control, i.e. creating an air inlet hot water curtain bypass


Winter operation

The water distribution system is constructed for approx. 120% overload. In the case of isolated cool zones, the excess water is diverted through the bypass directly in the cold-water basin. This process uses no fittings and the diversion takes place hydraulically. The start-up in winter poses no problems.


GEA Fan-assisted Natural Draft Cooling Towers

Natural Draft Cooling Towers can also be equipped with fans. The fans are installed at the air inlet for forced-draft air movement or on a deck above the fills to induce airflow. While airflow through a natural draft cooling tower is exclusively controlled by the height of the stack and the density difference between the cold and the hot air, the air is accelerated by the fans of a fan-assisted Natural Draft Cooling Tower to reduce the overall height of the structure. Increased air velocity, caused by the installation of fans, allows a compact design.

Fan-assisted Natural Draft Cooling Towers combine the benefits of natural draft cooling towers and the advantages of cell-type towers. If they are sufficiently high, no near-ground plumes will develop and no hot air will be recirculated to the air inlet where it could affect cooling capacity.

GEA fan-assisted Natural Draft Cooling Tower

Areas of Application

Fan-assisted Natural Draft Cooling Towers are used both for power station and for process cooling applications. They are the right choice for medium or large cooling water flows and are available as a hybrid alternative.

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Mehdi Khodakarami

Mehdi Khodakarami

Electrical Engineer

Phone No: +98 21 8878 5791-3
Fax No: +98 21 8878 6292

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