Natural draft cooling towers consist of large chimneys set on an extremely large base. The size of these towers makes them well suited to utility and power production plants which utilize large volumes of water. These large towers may also be found at nuclear facilities, or any structure that requires large amounts of cooling capacity. Natural draft cooling towers operate without the use of fans or blowers. Instead, they rely on principles of evaporation and water pressure to remove heat energy from process water.
Mechanical cooling towers utilize large fans to remove or collect heat from process water used in the facility. These fans force air through the water to extract the maximum amount of heat energy from the water. This energy can then be used within the facility to provide HVAC heating or industrial process heat. It may also be exhausted outside in order to keep process water at the desired temperature.
Mechanical cooling towers can be divided into two different categories depending on the placement of the fan. In a forced draft tower, the fan sits at the base of the tower to drive air up against the downward flow of the water. These units minimize erosion, condensation and noise issues. Induced draft units feature a fan placed at the top of the tower, which draws air down through the water. Induced draft cooling towers offer a high level of energy efficiency and effective heat exchange.
Hybrid Cooling Towers
Hybrid cooling towers rely on natural evaporation and water pressure during cooling but may also use a fan to assist the process as needed. These towers are specifically designed to minimize mechanical energy and maximize the efficiency of the cooling process. Fans may be used to handle peak loads or to redirect airflow when natural forces are insufficient. Fans may be placed anywhere within or around the tower as needed to maximize function.