A cooling tower is a construction (apparatus) for cooling water by a free air. Modern cooling towers are used mainly in engineering systems of circulating water service of the industrial enterprises to reduce temperature of the water which is taking away heat from the heat-exchange apparatus, compressors, etc. Cooling occurs mainly due to evaporation of some water which is coming down by gravity on a sprinkler in the form of films or drops. The temperature of the circulating water cooled in cooling towers, essentially influences work of the process equipment.

Water temperature history Effect on performance figures of the equipment
Temperature decrease of the water supplied to the condensers of turbines of TPP, for 1°С. Decrease of consumption by 1.2-2 KW/hr of equivalent fuel for generation of 1 KW-hour of the electric power.
Temperature increase of the water supplied to the condensers of compression refrigerating stations TPP, for 1°С. Decrease of vacuum in condensers by 0.5 % which is equivalent to decrease of turbine capacity by 0.4 % or to the steam waste by 0.5 %.
Temperature decrease of the water supplied to the condensers of compression refrigerating stations, on 1 °С Decrease by 2-4 % of the electric power for the drive of compressors.
Temperature decrease of the water supplied to the condensers of steam-ejection refrigerating stations, for 7°С (from 27 down to 20 °С) Decrease of steam consumption from 3.4 down to 2.1 tons for generation of 4GJ cold energy.
Temperature decrease of the water at calculations of sizes of heat-exchanging equipment for the facilities of petrochemical industry for 5 °С (from 30 down to 25°С) Decrease by 23 % of cooling surface of the heat exchangers and by 20 % of metal for their manufacturing.
Temperature decrease of the water by 2-3 °С used in the oil pyrolysis unit of 340 000 MTPA production rate. Decrease of consumption of fuel and energy resources by USD 518 000.-- a year.
Undercooling of water in summer time compared with design cooling temperature in the chemical plants. Decrease of annual production of development of soda ash approximately by 3-4%, ammonia - by 10, %, methanol - by 8%, sodium sulphide - by 4-5%, acetic acid - by 11%.

Cooling towers are subdivided, by type of sprinklers: into film-type cooling towers, drip-type cooling towers and spray-type cooling towers; by type of air supply: fan cooling tower, chimney-type cooling tower (air draft takes place due to lofty tower) and open type (or atmospheric) cooling tower which use the wind force and, partially, the natural convection for the air flow passing through the sprinklers.

Fan cooled tower are subdivided into sectional and detached cooling towers. Fan cooling towers provide deeper and consistent cooling of water and can withstand greater specific thermal loadings, than chimney-type cooling towers and atmospheric ones, but consume additional electric power. Cooling capacity of cooling towers is characterized by the value of water sprinkling concentration - the specific flow rate of cooled water per 1 m2 of irrigated area. At designing the type and sizes of the cooling tower and its basic elements are defined by technical and economic calculation depending on quantity and temperature of cooled water and parameters of a free air. Cooling towers in integral cooling systems of compressors of refrigerating stations of condensers can be located at the ground level, on the trestle or on the buildings with flat roofing. When installing the cooling tower inside of a production area it is necessary to provide an inflow of fresh air from the outside of the building and exhaust of return air to the outside by means of leak proof air ducts. Productiveness of the process equipment, quality and the cost price of manufactured products, fuel, electric power and raw materials consumption per unit of product, as well as the extent of utilization of advantages of systems of circulating water supply in technical and ecological aspects compared to the direct-flow systems depend on the overall performance of cooling towers.