Cooling Towers

COOLING TOWERS

In the power industry, energy in the form of heat is transformed to energy in the form of electricity. Unfortunately, t h i s t r a n s f o r m a t i o n i s n o t a c c o m p l i s h e d o n a o n e -to-one ratio. Although designers continuously seek newer and better ways to improve overall system efficiency, considerably more units of heat must be input that are realized as equivalent units of electric output. System equilibrium requires that this excess heat be dissipated ultimately to the atmosphere.

In an increasing number of cases, because of qualitative and quantitative restrictions regarding the use of natural waterways, plant make use of a closed circuit system typical of that depicted in figure. As shown, the system’sdependence on the river is limited to the requirement for a supply of makeup water and, perhaps, as a point of discharge of blow down. In these cases, the entire heat loads are dissipated by cooling towers, at the variety, application and operation of which are the subject of these article.

Define forced draft and induced draft cooling towers

If the fan is located at the bottom of the tower and air is blown by the fan up through the descending water it is called as forced draft cooling towers. If the fan is located at the top of the tower

and air enters through the louvers located on the tower’s side and drawn up and discharge through the

fan casing, it is called as induced draft.

What is the working principle of Cooling Towers?

The hot water is sprayed from the top of the tower, while the air is made to flow from the bottom of the tower to the top. This air cools the hot water in the cooling tower. Air vaporises a small percentage of water, there by cooling the remaining water. The air absorbs the heat and leaves at the top of the tower and cooled water leaves at the bottom and recirculated to the condenser.

How the atmospheric (or) natural draught cooling towers- are classified?

In atmospheric (or) natural cooling towers, the natural air provides the required Cooling without the use of fans. This is classified into three types.

1. Natural draft spray filled towers

2. Natural draft packed type towers.'

3. Hyperbolic cooling towers

How mechanical draft cooling towers are classified?

Mechanical draft cooling tower is classified into three types

1. Forced draft tower.

2. Induced draft counter flow tower

3. Induced draft cross flow tower.