What is the physical condition of steam inside a boiler drum___________________?
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Answer: B. wet
Explanation
Inside an operating boiler drum, boiling water and generated steam coexist in continuous thermal equilibrium at saturation temperature. The steam leaving the boiling water surface carries entrained moisture droplets, making its thermodynamic state wet and saturated. This wet steam mixture must pass through mechanical moisture separators before it can be considered dry or superheated. Dryness fraction defines the mass proportion of actual dry steam present in a total mixture of wet steam and water. Boiler drums use internal cyclone separators and scrubber baffles to reduce water droplet carryover from the saturated steam space. Operating at saturation pressure, the water and steam share the exact same corresponding saturation temperature.
Dry steam inside the drum is impossible without external superheating or exceptionally efficient internal moisture separation equipment. Saturated without the wet designation is inaccurate because boiling water inside the drum inherently produces a two-phase wet mixture. Superheated and supersaturated conditions occur only after steam leaves the drum and passes through separate heated superheater tubes.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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