What kind of steam is used in a feedwater heater if extraction steam from a turbine is utilized?

The use of extraction steam from a turbine in a feedwater heater typically involves superheated steam. Superheated steam is steam that has been heated beyond its boiling point at a specific pressure, which allows it to transfer heat efficiently when entering a feedwater heater. This high temperature enhances the heat transfer process, effectively raising the temperature of the feedwater before it enters the boiler, improving overall efficiency and reducing the risk of thermal shock.

In contrast, saturated steam exists at the boiling point for a given pressure and contains a significant amount of moisture when it is at this state. While it can also be used in heat exchange processes, it may not provide the same efficiency level as superheated steam in certain applications. Condensed steam refers to steam that has turned back into liquid water, which lacks the thermal energy needed for effective heating. Mixed phase steam contains both liquid and vapor phases and is less effective for heating applications since the presence of liquid can hinder heat transfer efficiency.

Therefore, using superheated steam allows for enhanced energy transfer in the feedwater heating process, promoting improved performance of the overall steam system.