Question 158Steam Plants - 1st Asst/Chief

70% to pass

Dirty generating tube surfaces may cause higher than normal superheater outlet temperatures because _______________.

Athe boiler must be over-fired to maintain the required rate of steam generation
Bthe screen tubes absorb excessive heat and transfer the increased temperature to the superheater
Cthe temperature of the gas leaving the generating banks will be lower than normal
Dgas laning will result causing overheating of the superheater
AI Explanation

The correct answer is A) the boiler must be over-fired to maintain the required rate of steam generation. Explanation: Dirty generating tube surfaces reduce the heat transfer efficiency of the boiler, so more heat input is required to maintain the same steam generation rate. To achieve this, the boiler must be over-fired, leading to higher than normal superheater outlet temperatures. The other options are incorrect because they do not accurately describe the effect of dirty generating tubes on superheater temperatures.

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