Question 68Steam Plants - QMED

The correct answer is B) decrease the vacuum in the main condenser. Air in the main condenser is harmful because it will decrease the vacuum in the main condenser. The main condenser is designed to create a strong vacuum to efficiently condense the steam exiting the turbine. The presence of air in the condenser reduces this vacuum, decreasing the pressure differential across the turbine and reducing the turbine's efficiency. This can adversely impact the overall performance of the steam plant. The other options are incorrect because: A) heat transfer is not the primary issue with air in the condenser, C) warping of the turbine casing is not a direct consequence, and D) the decreased turbine exhaust steam pressure is a symptom of the reduced vacuum, not the root cause.