Cooling Water Treatment

Additional Details

Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperaturee or, in the case of closed circuit dry cooling towers, rely solely on air to cool the working fluid to near the dry bulb air temperature.

Classification by build:

Package type

This type of cooling towers are factory preassembled, and can be simply transported on trucks as they are compact machines. The capacity of package type towers is limited and for that reason, they are usually preferred by facilities with low heat rejection requirements such as food processing plants, textile plants, some chemical processing plants, or buildings like hospitals, hotels, malls, automotive factories etc. Due to their frequent use in or near residential areas, sound level control is a relatively more important issue for package type cooling towers.

Field erected type

Facilities such as power plants, steel processing plants, petroleum refineries, or petrochemical plants usually install field erected type cooling towers due to their greater capacity for heat rejection. Field erected towers are usually much larger in size compared to the package type cooling towers. A typical field erected cooling tower has a pultruded FRP structure, FRP cladding, a mechanical unit for air draft, drift eliminator, and fill.

Heat transfer methods:

With respect to the heat transfer mechanism employed, the main types of towers are:

Dry cooling towers operate by heat transfer through a surface that separates the working fluid from ambient air, such as in a tube to air heat exchanger, utilizing convective heat transfer. They do not use evaporation.

Wet cooling towers or open circuit cooling towers operate on the principle of evaporative cooling. The working fluid and the evaporated fluid (usually water) are one and the same.

Fluid coolers or closed circuit cooling towers are hybrids that pass the working fluid through a tube bundle, upon which clean water is sprayed and a fan-induced draft applied. The resulting heat transfer performance is much closer to that of a wet cooling tower, with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure and contamination.