Boiler heat-recovery devices: location of the air preheater Identify where an air preheater is typically installed in the boiler flue-gas path relative to the economiser and chimney. Choose the correct location.
Mechanical Engineering
Steam Boilers and Engines
Difficulty: Easy
Choose an option
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ABefore the economiser (hotter gas goes first to air preheater)
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BBefore the superheater
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CBetween the economiser and the chimney
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DNone of these
Answer
Correct Answer: Between the economiser and the chimney
Explanation
Typical arrangement
- Superheater → Economiser → Air preheater → Chimney (gas progressively cools).
Reason
Air preheaters recover the lowest grade of heat (lowest gas temperatures) to preheat combustion air before it enters the furnace, so they are usually placed just before the chimney, downstream of the economiser.Final AnswerBetween the economiser and the chimney.