Question 603Steam Plants - Assistant Engineer

The correct answer is C) never exceed 170°F. The reason this is the correct answer is that the maximum allowable lube oil temperature leaving a large, main propulsion steam turbine bearing is typically limited to 170°F by industry standards and regulations. Exceeding this temperature can lead to increased wear and damage to the turbine bearings and other components. The other answer choices are incorrect because: A) maintaining a fixed temperature of 130°F may not be practical or necessary for all steam turbine systems; B) the lube oil outlet temperature from the centrifugal purifier is not directly related to the maximum allowable temperature from the turbine bearing; and D) a temperature rise of more than 70°F above the inlet temperature could potentially exceed the 170°F limit.