PT317_DAY10_FALLING EVAPORATORS

Which one of the following is not a type of evaporator?

• Forced Circulation

• Natural Circulation

• Nucleate Boiling

• Gasketed evaporators

Which one of the following is not a suitable application of evaporators?

• Refrigeration

• Cooling

• Heating

• Crystallisation

Crystallizers are one of the most important setups in industries nowadays. It is solely used to dry a solution to an extent to obtain the crystals of the solute. Which one of the following is the most suitable operation to carry out this process?

• Forced Circulation

• Natural Circulation

• Nucleate Boiling

• Non - Nucleate Boiling

Why don’t we use Natural convection for evaporating waste streams, crystallizers, and viscous fluids?

• Slow process

• Sedimentation problem

• Prevents fouling at the heating surface

• Causes overheating

Which one of the following is not a subset of Nucleate boiling evaporators?

• Climbing Film Evaporator

• Rising Film Evaporator

• Short-tube Vertical Evaporator

• Falling Film Evaporator

What is the driving force for evaporation to take place?

• Difference in partial pressure

• Difference in pressure

• Difference in Concentration

• Difference in temperature

Which one of the following statement is incorrect about the factors leads to single effect operation of climbing film evaporator?

• When the vapour is contaminated and cannot be recycled

• The feed is highly corrosive, requiring expensive construction materials

• The liquid has low vapour pressure

• The energy cost to produce the steam heating is low

Which one of the following statements is correct about the nucleate boiling phenomenon in climbing tube evaporators?

• There is no nucleate boiling

• There is nucleate boiling throughout

• Nucleate boiling near the entrance but not later

• Nucleate boiling near the exit and nowhere else

In order to maintain conservation of mass as this fluid fall proceeds in a falling film evaporator, the downward vapour velocity ___________

• Decreases

• Increases

• Remains same

• Oscillates

Which one of the following cannot be regarded as a demerit of falling film evaporator?

• High headroom requirement

• Corrosive fluids cannot be used

• Large product holdup

• Recirculation needed