Natural Draft Cooling Towers

PRESENTED BY: ABDULLAH MANSOOR

ROLL#0042

SECTION MB

Contents

What is a cooling Tower Types of Cooling Tower Natural Draft Cooling Tower Common terms use in Cooling Towers Construction of natural Cooling Towers Working of Natural Cooling Tower Strategies to improve efficiency

Cooling towers

“A cooling tower is a device that is use transfer heat and cool water for reuse in a process”

Cooling towers are used in process industries to cool off effluent water from various heat transfer equipment e.g., condensate from a condenser.

The cooled water is sent back to the process for reuse, thus emphasizing conservation of water.

Cooling tower in industries

Types of cooling tower

Cross and Counter Flow in Natural Cooling Towers

What is a Natural Draft Cooling Tower What is a

Natural Draft Cooling Tower?

A Few Important Terms

Components

How it Works

Remarks

A natural draft cooling tower is a means to remove waste heat from a system and release it into the atmosphere.

Typically used at oil refineries, chemical plants and power plants to remove heat absorbed from circulating cool water systems.

Two types of Heat loss take place in the cooling tower1. Sensible heat loss 2. Evaporation

Why evaporation causes cooling ?

Evaporation results in vapor escaping from the surface of the liquid.

The vapors require energy to escape.

That energy is heat.

As vapors escape the surface, they carry with them some heat content of the liquid, and thus cause the liquid surface to cool.

Important Terms Wht is a

Natural Draft Cooling Tower?

A Few Important Terms

Components

How it Works

Wet Bulb Air Temperature Adiabatically adiabatic cooling Dry Bulb Air Temperature Natural Draft Stack Effect Humidity

• What is a Natural Draft Cooling Tower?

• A Few Important Terms

• Components

• How it Works

• Remarks

Components

What is a Natural Draft Cooling Tower?

A Few Important Terms

Components

How it Works

Remarks

Supply Basin Tower Pumps Cooling Towers

Vertical Ribs Reinforced Concrete Shell Internal Void Diagonal Columns

Hot Water Inlet Fill

Splash Film

Hot Water Distribution System Cold Water Collection Drift Eliminators - Drift eliminators are used to control this

drift loss from the tower. (Mist)

• What is a Natural Draft Cooling Tower?

• A Few Important Terms

• Components

• How it Works

• Remarks

Detail Components

Basic working principle of a cooling tower

Considering an example of an air-water system, the basic working principle of a cooling tower can be listed as,

1. Hot water and relatively cool ambient air enter the cooling tower.

2. Heat transfer between the air stream and the water stream occurs.

3. Hot water transfers its heat to the ambient air and becomes cool.

4. Cool water is removed from the cooling tower and sent back to the process plant.

5. The resulting hot air rises and is, generally, removed from the top of the tower by virtue of its low density.

How it Works

What is a Natural Draft Cooling Tower?

A Few Important Terms

Components

How it Works

Remarks

Strategies to improve cooling tower performance

When designing a cooling tower, always use the highest wet-bulb temperature as reference.

Monitor the range and approach carefully during the design. High range and low approach leads to good performance. Improve the quality of water to be cooled by the tower resulting in

low utilization of make-up water. Regularly monitor the tower for scale build-up and biological

impurities. Regularly monitor the flow of water and air inside the tower

References Literature:

Dr. N.P. Cheremisinoff, Handbook of Chemical Processing Equipment, 1st edition, Butterworth-Heinemann, USA, 2000.

J. M. Coulson, J.F. Richardson, J.H Harker, J.R. Backhurst, Chemical Engineering Volume 1 – Fluid Flow, Heat Transfer and Mass Transfer, 6th edition, Butterworth-Heinemann, USA, 1999.

San Diego County Water Authority, Technical Information for Cooling Towers Using Recycled Water, San Diego, USA, 2009.

Training Session on Energy Equipment, Cooling Towers, UNEP, 2006.

Websites / URL’s: http://www.cti.org/whatis/coolingtowerdetail.shtml http://www.engineeringtoolbox.com/ http://www.deltacooling.com/resources/principles-of-cooling-

towers/