Extraction steam from turbines is used to preheat feedwater in a feedwater heater. From where is the extraction steam typically taken?

• A. From the main steam inlet to the boiler.
• B. From turbines.
• C. From the condenser.
• D. From the auxiliary boiler.

Answer: (B)

Extraction steam is taken from the turbine itself. After steam expands to do work in the turbine, a portion is diverted at an intermediate stage to a feedwater heater. This steam, still at a useful temperature and pressure, transfers its heat to the feedwater, raising its temperature before it enters the boiler. This arrangement improves overall efficiency by recovering heat that would otherwise be wasted when the steam exhausts to the condenser. It’s not taken from the main steam inlet (which feeds the turbine), not from the condenser (where steam is already condensed and has little usable heat), and not from an auxiliary boiler. In practice, several stages of turbine extraction can feed multiple feedwater heaters in a cascade to maximize heat recovery.