disitllation Flashcards
only 1 wrong
Distillation separates components in a mixture based on:
viscosity
boiling point
answer B
In a simple, continuous distillation column, the less volatile liquid tends to travel ________.
up the column as a vapor
down the tower as a liquid
answer B
What are the liquid materials collected at the bottom of a distillation column sometimes called?
lights
heavies
answer B
When a vapor condenses to a liquid:
sensible heat
latent heat
answer B
What is a measure of a substance’s volatility and its tendency to form a vapor?
vapor pressure
Vapor threshold
answer A
For two liquids C and D, if D has a lower vapor pressure than C, which is true?
D has a higher boiling point than C
D has a lower boiling point than C
answer A
What is another name for the part of a distillation column where the liquid overhead stream gets enriched in the lighter, more volatile components?
the downcomer
the fractionating section
answer B
Where is the stripping section of a distillation column located?
below the feed tray
above the feed tray
answer A
What is an advantage of an atmospheric pressure distillation system?
does not require additional overhead equipment
lower boiling points of liquids
answer A
The operating condition for a distillation tower in which the feed, along with overhead and bottom products, is stopped is called ________.
high pressure distillation
total reflux
answer B
The drop in pressure from bottom to top in a distillation tower is called the ________.
descending pressure
differential pressure
answer B
What happens to inert or noncondensable gases in the feed in a distillation system?
They eventually vent to a flare or other system.
They are pumped out with the condensate.
answer A
Which of the following is the most critical to good distillation control?
Controlling the volatility of components
controlling the column temperature
answer B
Which maintenance operation requires the entire system to be shut down?
repairing damaged trays
adjusting vapor rates
answer A
When does flooding occur in a distillation system?
When the rate of liquid flowing down a column exceeds the capacity of a downcomer
When the velocity or turbulence of the vapor pulls in or carries along liquid droplets or solid particles
answer A
If an upset occurs causing the packing to flood due to an increase in feed flow, what changes would you see in the differential pressure across the packing?
decrease of differential pressure
increase in differential pressure
answer B
What should the process technician monitor for early warning signs of flooding, weeping, fouling, and maldistribution?
unusual sounds
column temperature and pressure profiles
answer B
Process technicians routinely adjust the set point for reflux flow rate and ________ based on sample results.
circulator pressure
reboiler heat duty
answer B
When do process technicians have to prepare many work permits?
during maintenance of a distillation column
during extreme emergencies
answer A
What may be required to remove and replace packing and distributors in tall distillation towers?
Lighter weight materials
tall oversized cranes
answer B
Due to the impracticality of isolating the reflux condenser and reboiler from the distillation column, what is the typical protection against overpressure?
A single overpressure protection device sitting at the top of the distillation column
A single overpressure protection device situated half-way up the distillation column
answer A
What should be done to the reflux flow if the top temperature is too high?
increase the flow
decrease the flow
answer A
If the trays in a distillation column were to become dry due to the feed entering too hot, which of the following changes would you see in the column?
Temperature would gradually decrease from the bottom of the column to the top.
The differential pressure would drop
answer B
If the overhead product was out of specification (too many heavies in overhead product) which of the following might be done to correct it?
increase reflux flow
decrease reflux flow
answer A
If a valve tray corroded to the point that several valves rusted away and came loose from the tray, leaving large holes in the tray, what would you expect the differential pressure across the column to do? (Hint: How would the holes affect the liquid on the tray?)
increase
decrease
answer B
If you have a mixture of gasoline (BP - 200 C) and Diesel (BP - 360 C), which will be the over head product
Gasoline
‘
Diesel
answer A
If you have a mixture of gasoline (BP - 200 C) and Diesel (BP - 360 C), which will have a higher vapor pressure?
Gasoline
Diesel
answer A
After changing a tower process variable, the tower will reflect this change from top to bottom quickly.
true
false
answer B
What part of the tray determines how much liquid is held on the tray?
Weir
Riser
answer A
If the bottoms product has too many light components in it, what adjustment should be made?
increase boil up rate
increase reflux rate
answer A
If the pressure on a distillation tower is increased
The boiling points increase
The boiling points decrease
answer A
The liquid level in a thermosyphon reboiler is mainly determined by the
liquid level inside tower
flow through the reboiler
answer a
If the trays in a distillation column were to become dry due to the feed entering the tower too hot, which of the following changes would you see in the column?
Differential would drop
differential would increase
answer A
