Main Types of Cooling Towers
Cooling towers are primarily categorized by how they move air:
1. Mechanical Draft Towers
These use large mechanical fans to force or draw air through the tower. They are the most common type.
- Forced Draft: The fan is located at the bottom and forces air into the tower. This design is less common.
- Induced Draft: The fan is located at the top and pulls air through the tower. This is the most efficient and prevalent design for large installations.
2. Natural Draft Towers
These massive, hyperbolic (hourglass-shaped) towers use the natural principle of convection—hot air rises. The warm, moist air inside the tower is less dense than the cooler, drier air outside, causing it to rise naturally and draw in fresh air at the bottom. They are iconic structures often seen at nuclear or large fossil-fuel power plants and require no large fans, saving energy.
Key Components
- Frame and Casing: The external structure, often made of fiberglass or metal for durability.
- Fill: The internal material that increases surface area and contact time between air and water.
- Cold Water Basin: The reservoir at the bottom that collects the cooled water.
- Drift Eliminators: Baffles that capture water droplets in the air stream to prevent water loss.
- Fan(s): The mechanical drivers for air movement (in mechanical draft towers).
- Nozzles: Spray the hot water evenly over the fill.