This set of Heat Transfer Operations Multiple Choice Questions & Answers (MCQs) focuses on “Boilers – Types of Reboiler”.
Explanation: The vertical thermosyphon reboiler is a natural convection reboiler because it does not depend on fans or pumps to carry the vapour or coolant rather it is the gravity and natural forces that circulate the fluids.
Explanation: The horizontal reboiler is a forced convection reboiler because it does depends on fans or pumps to carry the vapour or coolant because of its horizontal setups where the gravity and natural forces cannot circulate the fluids.
Explanation: The fired tube reboiler can be recognized from the fact that the heating medium is fire or the burning fuel supplied to it, hence the given reboiler is a fire tube reboiler.
Explanation: The kettle reboiler is necessarily not a shell and tube heat exchanger rather it is an oversized shell with half filled water and the tubes submerged in it. The vapour exit is at the top and the fluid inlet at the bottom.
Explanation: The internal reboiler is special type of reboiler in which the heating tube is placed within the distillation column and there are no external setups or equipment required for its operation.
6. The boiling occurs inside the tubes in ___________ thermosyphon reboiler and inside shell in ____________ thermosyphon reboiler.
a) Vertical, Horizontal
b) Horizontal, vertical
c) Vertical, vertical
d) Horizontal, Horizontal
Explanation: The boiling occurs inside the tubes in vertical thermosyphon reboiler as it has lesser pressure drop in this case and inside shell in Horizontal thermosyphon reboiler because the heating fluid now has larger pressure drops.
7. In vertical thermosyphon natural convection reboiler, the solution is heated in the shell with the hot fluid in the tubes.
Explanation: The boiling occurs inside the tubes in vertical thermosyphon reboiler as it has lesser pressure drop in this case and also increases the flow gradient into the distillation column.
8. In horizontal thermosyphon natural convection reboiler, the solution is heated in the shell with the hot fluid in the tubes.
Explanation: The statement is correct, in horizontal thermosyphon natural convection reboiler, the solution is heated in the shell with the hot fluid in the tubes as this design has the advantage of preserving the natural circulation concept while allowing a lower headroom as compared to vertical thermosyphon type.
9. In a vertical thermosyphon re-boiler, it is due to the __________ difference that the circulation in the liquid occurs, between vapour-liquid mixture from the re-boiler and the liquid through the down-comer to the re-boiler.
Explanation: As the liquid gets heated, its volume increases and hence its density decreases, this in turn cause a driving force for the lighter fluid to move upwards and reach the Distillation column.
10. Which one of the following reboiler is best suited for high vaporization rate up to about 80% of the feed?
a) Vertical thermosyphon reboiler
b) Kettle Reboilers
c) Horizontal thermosyphon reboiler
d) Flash Reboilers
Explanation: The Kettle reboilers give an evaporation rate of 80%, flash types have 90% and thermosyphon types have around 60%.
Sanfoundry Global Education & Learning Series – Heat Transfer Operations.
To practice all areas of Heat Transfer Operations, here is complete set of 1000+ Multiple Choice Questions and Answers.
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