Introduction:
In thermal power plants, the deaerator is a crucial component used to remove dissolved gases from the feed water. By removing these gases, the deaerator helps to ensure the efficient operation and longevity of the power plant's equipment, including the boiler and steam turbine.

Importance of removing dissolved gases:
The presence of dissolved gases in the feed water can have several detrimental effects on the operation of a thermal power plant. These effects include:

1. Corrosion: Dissolved gases such as oxygen and carbon dioxide can lead to corrosion of the boiler and other equipment. Corrosion can cause damage to the internal surfaces of the equipment, leading to reduced efficiency and increased maintenance costs.

2. Scaling: Dissolved gases can contribute to the formation of scales and deposits on heat transfer surfaces. These scales act as insulators, reducing heat transfer efficiency and potentially causing overheating and equipment failures.

3. Steam quality: Dissolved gases in the feed water can also affect the quality of the steam produced. High levels of dissolved gases can lead to foaming and carryover, which can contaminate the steam and cause damage to downstream equipment, such as the steam turbine.

Role of the deaerator:
The deaerator is specifically designed to remove dissolved gases from the feed water before it enters the boiler. It accomplishes this through a combination of mechanical and thermal processes:

1. Mechanical process: The incoming feed water is sprayed into the deaerator, creating a large surface area for the gases to be released. This process helps to strip the dissolved gases from the water.

2. Thermal process: The deaerator is equipped with a steam heater, which raises the temperature of the feed water. As the temperature increases, the solubility of the dissolved gases decreases, aiding in their removal.

The deaerator typically operates under vacuum conditions to further enhance the removal of dissolved gases. The gases that are released from the feed water are vented out of the deaerator.

Conclusion:
In conclusion, the deaerator in thermal power plants plays a vital role in removing dissolved gases from the feed water. By eliminating these gases, the deaerator helps to prevent corrosion, scaling, and steam quality issues, ensuring the efficient and reliable operation of the power plant's equipment.