Question 632Steam Plants - Assistant Engineer

70% to pass

When turbine rotor shafts extend through the casing, an external source of sealing steam is used in conjunction with labyrinth packing to _______________.

Aseal the casing during periods of low casing pressure
Bmaintain the rotor journal temperature
Cseal the casing during periods of high casing pressure
Dprovide a constant flow to the gland leak off condenser
AI Explanation

The correct answer is A) seal the casing during periods of low casing pressure. When turbine rotor shafts extend through the casing, an external source of sealing steam is used in conjunction with labyrinth packing to prevent air from entering the casing during periods of low casing pressure. This is necessary to maintain the proper pressure differential across the turbine and prevent air from contaminating the steam flow. The other options are incorrect because they do not directly address the purpose of using sealing steam with labyrinth packing in this scenario.

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