From where does the deaerator get its steam?

• A. Only from low-pressure steam
• B. A combination of extraction steam from turbine and reduced pressure steam off main steam
• C. From electrical heaters only
• D. From recycled steam

Answer: (B)

The deaerator gets its steam primarily from a combination of extraction steam from a turbine and reduced pressure steam off the main steam line. This is important because the purpose of a deaerator is to remove dissolved gases, particularly oxygen and carbon dioxide, from feedwater to prevent corrosion in the boiler system.

The extraction steam from the turbine provides the necessary heat to elevate the temperature of the feedwater, which helps in the removal of these gases. Meanwhile, the reduced pressure steam off the main steam line ensures that there is a consistent supply of steam available for the deaerator operation, even when the turbine is not fully loaded, thus improving the efficiency and reliability of the system.

Using only low-pressure steam would not provide sufficient energy or temperature required for effective deaeration. Electrical heaters are typically used as a supplementary source of heat but are not the primary means of providing steam. Recycled steam might be used in some systems, but it does not define the primary source of steam input for the deaerator in general operation.