Natural Draft Cooling Towers are used to cool circulating water in industrial and manufacturing processes, during which heat is produced from different kinds of energy (chemical, mechanical, electrical and others). If the heat is not used in a technological process it converts into waste heat which must be transferred to the atmosphere by the cooling tower. Here water serves as a cooling element.

Natural Draft Cooling Towers are most commonly used in the power industry. They are also responsible for discharging desulphurized flue gases from power units boilers. To achieve this, a pipe of 6m in diameter made of plastic through which flue gases are lead to the center of cooling tower, is injected through tower shell (last picture in the gallery below).

Natural Draft Cooling Tower is quite expensive to build but its exploitation replaces tens of mechanical draft cooling tower cells.

Natural draft cooling towers consist of reinforced concrete chimneys which take the shape of a rotary hyperboloid. When it comes to smaller towers, the chimneys are made of steel and take the shape of many-sided truncated pyramid. Hyperboloid shape of reinforced concrete chimneys results from resistance reasons (shell which has 2 radiuses of curvature is more stiff). Esthetic qualities of this kind of a shape are also important. When cooling towers are build in seismic zones then even big towers (h= over 100 m) are often made of steel.