Question 36Steam Plants - Assistant Engineer

The correct answer is A) condensing of the exhausting steam. The main condenser's vacuum is primarily caused by the condensation of the exhausting steam. As the steam from the engine exhaust enters the condenser, the cooling water circulating through the condenser coils causes the steam to condense, creating a vacuum that helps draw in more steam and maintain the engine's efficiency. This condensation process is the primary driver of the vacuum within the main condenser, which is a crucial component in the overall operation of the steam plant. The other options are incorrect because they are not the primary causes of the vacuum in the main condenser. The after condenser loop seal, the main air ejector, and the suction drawn by the condensate pump all play secondary roles in maintaining the vacuum, but the condensation of the exhausting steam is the primary and most significant contributor.