250+ TOP MCQs on Boilers – Types of Reboiler and Answers

Heat Transfer Operations Multiple Choice Questions on “Boilers – Types of Reboiler”.

1. 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

Answer: a
Clarification: 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.

2. In vertical thermosyphon natural convection reboiler, the solution is heated in the shell with the hot fluid in the tubes.
a) True
b) False

Answer: b
Clarification: 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.

3. In horizontal thermosyphon natural convection reboiler, the solution is heated in the shell with the hot fluid in the tubes.
a) True
b) False

Answer: a
Clarification: 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.

4. 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.
a) Density
b) Pressure
c) Temperature
d) Concentration

Answer: a
Clarification: 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.

5. 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

Answer: b
Clarification: The Kettle reboilers give an evaporation rate of 80%, flash types have 90% and thermosyphon types have around 60%.