At what chimney height condition does maximum combustion gas discharge occur_____________________?
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Answer: C. equal to the height of the hot gas column producing draught
Explanation
Chimney draft is produced by the density difference between hot internal gases and cold air. Maximum discharge occurs when the chimney height equals the theoretical hot gas column height. Extending the chimney beyond this specific height increases friction losses without adding draft. Buoyancy forces drive combustion gases upward through chimneys in natural draft systems. Frictional resistance inside the flue increases with taller chimney structures. Optimizing chimney height balances buoyancy driving force against internal pipe friction.
Power plant designers calculate optimum chimney heights to ensure adequate flue gas dispersion. Environmental dispersion requirements often require taller structures than purely thermodynamic optimums. Draft calculations prevent poor boiler combustion caused by insufficient pressure differences. Infinitely long chimneys would experience excessive friction, choking the gas flow entirely. Arbitrary heights like two hundred meters depend entirely on specific boiler plant capacities. Building height comparisons do not dictate thermodynamic draft and gas discharge limits.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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