Question 49Steam Plants - Assistant Engineer

The correct answer is D) condenser vacuum. The reasoning is that scale buildup in the first-stage nozzle of an air ejector system can impede the flow of air and steam, leading to a decrease in the condenser vacuum. This is because the air ejector system is responsible for maintaining the vacuum in the condenser by removing non-condensable gases, and any restriction in the nozzle will reduce the efficiency of this process, resulting in a lower condenser vacuum. The other options are incorrect because they are not directly affected by scale in the air ejector nozzle. The air ejector steam supply pressure (A) and the low-pressure turbine exhaust temperature (B) are not directly related to the condenser vacuum, while the condensing temperature in the condenser (C) is more dependent on the condenser vacuum itself.