What is the purpose of steam ejectors on the surface condenser of a turbine-driven system?

• A. To remove non-condensables passively
• B. To cool the turbine bearings
• C. To increase feedwater temperature
• D. To create a proper operating exhaust vacuum

Answer: (D)

Maintaining a strong vacuum in the surface condenser is essential for efficiently condensing the turbine’s exhaust and minimizing backpressure on the turbine. Steam ejectors achieve this by using high-pressure steam as the motive fluid to create a high-velocity jet that entrains the non-condensables (air and other gases) from the condenser and discharges them away. This active suction keeps the condenser pressure near its operating vacuum, which improves heat transfer and turbine efficiency. They’re not simply passive removal devices, nor are they meant to cool bearings or raise feedwater temperature; their primary role is to establish and maintain the proper exhaust vacuum.