Raising the liquid level inside a vertical tube evaporator leads to an increase in ____________?
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Answer: D. Neither A. and B.
Explanation
Raising liquid level increases hydrostatic head pressure at the bottom of evaporator tubes. Higher hydrostatic pressure raises the local boiling point temperature of the liquid solution. This suppresses boiling and reduces both circulation velocity and liquor-film coefficients. Vertical tube evaporators rely on natural thermal circulation driven by vapor bubble generation. Hydrostatic head is the pressure exerted by a column of fluid due to gravity. Film coefficients measure convective heat transfer effectiveness along evaporator heating surfaces.
Evaporator operators maintain optimal liquid levels to prevent dryout while avoiding hydrostatic suppression. Poor circulation velocities in vertical tube units lead to accelerated fouling and scale formation. Maximizing film coefficients requires careful control of liquid levels in natural circulation evaporators. Velocity of circulation decreases rather than increases when hydrostatic head suppression occurs. Liquor-film coefficient drops due to suppressed boiling and reduced natural circulation velocities. Option D is incorrect because raising liquid levels definitely impacts circulation and film coefficients.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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