But even there, the offshore discharge water outlet requires very careful design to avoid environmental problems. Some coal-fired and nuclear power plants located in coastal areas do make use of once-through ocean water. A cooling tower serves to dissipate the heat into the atmosphere instead and wind and air diffusion spreads the heat over a much larger area than hot water can distribute heat in a body of water. Furthermore, discharging large amounts of hot water may raise the temperature of the receiving river or lake to an unacceptable level for the local ecosystem. If that same plant had no cooling tower and used once-through cooling water, it would require about 100,000 cubic metres an hour and that amount of water would have to be continuously returned to the ocean, lake or river from which it was obtained and continuously re-supplied to the plant. The largest users of cooling water in a power plant are the surface condensers that condense the exhaust steam from the large steam turbines that drive the electrical generators.

gallons per minute) and the system requires a supply water make-up rate of perhaps 5 percent (i.e., 3,600 cubic metres an hour). The circulation rate of cooling water in a typical 700 MW conventional coal-fired power plant with a cooling tower amounts to about 71,600 cubic metres an hour (315,000 U.S. The primary use of large, industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in industrial facilities such as petroleum refineries, petrochemical and chemical plants, natural gas processing plants, fossil-fuel power plants and nuclear power plants. Most fill in modern cooling towers is plastic material.

Film fill is composed of thin sheets of material upon which the water flows. Splash fill consists of material placed to interrupt the water flow causing splashing. To achieve better performance (more cooling), a media called fill is used to increase the contact surface area between the air and water flows. The average ambient air wet-bulb temperature chosen as the design basis essentially determines the size of the cooling tower, and the size of a cooling tower is inversely proportional to the design wet-bulb temperature. Such towers can cool water to a temperature that approaches the wet-bulb temperature of the ambient air. The net result is that the air leaving the tower is saturated with water vapor and the unevaporated water leaving the cooling tower has been cooled.Īn evaporative cooling tower is referred to as a wet cooling tower or simply a cooling tower. This process is known as evaporative cooling.

The heat required to evaporate part of the water is derived from the water itself and thus causes the water to cool. That causes part of the warm water to evaporate and the air absorbs that evaporated water. 5 Some commonly used terms in the cooling tower industryīasically, a cooling tower intimately contacts a flow of warm water with a flow of ambient air which is not saturated with water vapor (i.e, air which contains less water vapor than it is capable of containing).

Circulated water drift cooling tower