Evaporative cooling tower uses technologies of both water and air to extract the heat from the power plant. By making the fullest use of air and water, the footprint needed for an air cooling system as well the amount of water needed for a power plant can be reduced. It is used in thermal generation technologies such as geothermal, coal, CSP, natural gas and more. It circulates the air above the cooling water to generate the cooling water evaporation and simultaneously liquidize the steam and pushing the turbine back into a liquid state. It circulates the available cooling water, and henceforth extremely reducing the water consumption of the plant. When the water is evaporated, make up water is needed, however the make up water is needed in the magnitude of 2-5% of the total flow.

Operating Principles

The cooling tower operation is all about exchange and evaporative of sensible heat. The air and water is mixed at dissimilar temperature to remove the latent Heat of Vaporization, bringing a cooling effect to the hot water. A portion of water is transferred into the vapor state to get the cooling effect and the latent heat of evaporation is released as a result of it.

The heat rejection solution to the industrial process means the technical addition of the cooling tower.The cooling tower moves heat from one process to another process and eventually release it to the ambiance.

In general operation, continuously recalculating the waste heat captured by the water for a refrigeration compressor or a process heat exchanger and the hot water is driven to the top of the tower and released over the cooling tower. Evaporative action eliminates the heat from the water and adds it to the air. In order to pick up more heat, the fan stack cooled water returned to the process exchanger discharges the warm, moist air.

Cooling Tower Classification

Cooling tower is classified according to the method by which air is introduced to the tower. The cooling tower is classified according to the type of drafts, which are

Natural Draft

Natural draft cooling tower employs the stack effect of the chimney above the packing to generate air flow upwards via the packing in the counter flow to the water. This technology demands low maintenance cost, but capital cost is high due to the extreme height is mandatory to generate the draught.

Mechanical Draft

The complete control over the air supply is achieved when fans are used to move the air via the tower.Technologies are compact, minimum pumping head, close control over water temperature, low capital cost. It is further classified as,

  • Forced Draft Tower – Fans are located at the air intake and blow ambient air into the tower across the packing.
  • Induced Draft Tower – Fans are located in the air outlet from the tower, generally over the top.

It is additionally classified based on the water flow direction and type of air,

Counter Flow

In an induced draught tower, the fan produces vertical airflow upwards the tower across the packing in opposition to the flow of water. Therefore, the coldest water comes in contact with the driest water.

Cross Flow

In an induced draught tower, the fan produces horizontal airflow as the water drops across the airstream.

Co Current Flow

Generally, water and air flows in the same direction parallel to each other.

Also Classified as

  • Factory Assembled Cooling Tower
  • Field Erected Cooling Tower

Important Mechanical Component of Cooling Tower

  • Fans
  • Louvers
  • Speed Reducers / Gear Reducers
  • Drift Eliminators
  • Drive Shaft
  • Water Distribution System
  • Framework/Structure
  • Filling/ packing
  • Casing

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