Deck 15: Distillation Systems

Question 1

Two basic tower designs include:

A) packed and tray
B) plate and packed
C) bubblecap and sieve
D) valve and packed
E) a & b

Answer 1

plate and packed

Question 2

Overlap can be minimized by:

A) refluxing
B) increasing pressure
C) reboiling
D) a & c

Answer 2

a & c

Question 3

High bottoms temperature in a distillation tower are controlled by :

A) increase over head flow and decrease bottoms flow
B) decrease overhead flow and increase bottoms flow
C) stop feed flow and cut bottom temperature
D) open side-streams

Answer 3

increase over head flow and decrease bottoms flow

Question 4

List and describe the three technology periods of distillation.

Question 5

Feed composition changes have very little impact on the energy balance but significant impact on the material balance.

Question 6

Calculate the total vapor pressure exerted by the mixture: 25% hexane 20.6 psia @ 175F, 25% heptane 8.8 psia @ 175F, and 50% benzene 14.7 psia @ 176 F. Give answer in psia.

A) 14.7 psia
B) 44.1 psia
C) 22.05 psia
D) 34.7 psig

Question 7

Puking is most closely related to:

A) reduced partial pressure
B) excessive vapor pressure
C) low temperature
D) high temperature

Question 8

The process of vaporizing liquids at lower temperatures by reducing pressure:

A) azeotropic distillation
B) fractional distillation
C) vacuum distillation
D) adsorption distillation

Question 9

Tube shaped funnels that allow fluid transfer between plates in a tower:

A) riser
B) bubble-cap
C) downcomer
D) sieve

Question 10

The temperature at which the heaviest component begins to boil:

A) IBP- initial boiling point
B) FBP- final boiling point
C) ABP- average boiling point
D) Dew point

Question 11

Excessive liquid flowing down a tower that blocks vapor flow up the tower:

A) puking
B) flooding
C) surging
D) reflux

Question 12

A binary mixture contains:

A) lighter hydrocarbons
B) is heavier than a ternary mixture
C) two or more components
D) three compounds in a mixture

Question 13

Boil-up rate is defined as:

A) the temperature at which a liquid turns to vapor
B) the vapor-liquid balance returned to tower from the reboiler
C) the vapor-liquid reflux balance returned to tower from overhead accumulator.
D) the total amount of vapor moving up the column.

Question 14

Draw a distillation tower system. Include (3) three control loops, preheater, condenser, kettle reboiler, distillation column.

Question 15

What is the composition of side stream #2z?

Question 16

The sum of the products entering the column equals the sum leaving:

A) energy balance
B) fractional balance
C) material balance
D) total balance

Question 17

Packed towers use specially designed packing materials to reduce surface area during the distillation process:

Question 18

Distillation columns have two major types of separation grids: plate and packing. Plate towers have the following tray types:

Question 19

Packed towers have the following types of packing:

Question 20

Liquid distillate returned to the tower is called:

A) boil-up rate
B) reflux rate
C) total reflux
D) incomplete separation

Question 21

The temperature at which a liquid mixture turns to vapor:

A) boil-up rate
B) IBP
C) FBP
D) boiling point
E) dew point

Question 22

What is the overhead composition?

Question 23

The upper section of the tower is referred to as:

A) feed section
B) rectifying section
C) enriching section
D) stripping section
E) b & c

Question 24

Condensed tower product that is pumped back into a tower to increase product purity and control temperature:

A) overlap
B) reflux
C) side-stream
D) accumulation

Question 25

The condensed gas taken from a distillation tower is called:

A) residuum
B) distillate
C) condensate
D) distillation

Question 26

Distillation is best defined by the following statement:

A) the separation of components in a mixture by tower segregation
B) the fractional separation of a binary mixture by tray filtration
C) the azeotropic process designed to separate hydrocarbons by fractional boiling points.
D) the separation of components in a mixture by boiling point

Question 27

The lower section of the tower is referred to as:

A) feed section
B) rectifying section
C) enriching section
D) stripping section
E) b & c

Question 28

The tray located below the inlet feed line is called the:

A) mid section tray
B) pumping section tray
C) feed tray
D) valve tray

Question 29

Each tray in a distillation column has a different molecular structure.

Question 30

The varying temperatures across the tower:

A) temperature gradient
B) temperature profile
C) temperature overlap
D) temperature delta

Question 31

List three process variables that can be used to break a flood:

Question 32

List the critical steps used to start-up a distillation system. (DEXTER?)

Question 33

-Refer to Bottom VLE graphic above. On a VLE chart the bottom curve is referred to as:_________________ .

Question 34

A ternary mixture:

A) lighter hydrocarbons
B) is heavier than a ternary mixture
C) two or more components
D) three compounds in a mixture

Question 35

When a heat exchanger is used to convert all of the overhead vapors to liquid, it is called:

A) normal overhead condenser
B) total reflux
C) total condenser
D) partial condenser

Question 36

-Refer to Bottom VLE graphic above. On a VLE chart the top curve is referred to as:_________________ .

Question 37

All of the following are principles of distillation except:

A) heat increases vapor pressure
B) pressure increases boiling point
C) vacuum decreases boiling point
D) forms and breaks molecular bonds

Question 38

The larger the difference between partial pressures the harder it is to separate the fractions by boiling point.

Question 39

Using information from question 6, calculate the % component in vapor of hexane:

A) 20%
B) 25%
C) 30%
D) 35%

Question 40

Vapor distillate returned to the tower is called:

A) boil-up rate
B) reflux rate
C) total reflux
D) incomplete separation

Question 41

The vapor medium suspended above a boiling mixture is enriched with the components that have the lowest boiling points.

Question 42

Heat that cannot be sensed or measured:

A) latent
B) sensible
C) kinetic
D) potential energy

Question 43

Incomplete separation of components in a mixture:

A) overlap
B) puking
C) temperature gradient
D) overloading

Question 44

-Refer to Bottom VLE graphic above. The initial bubble point temperature for a butane mole fraction of 40% is:_________________ .

Question 45

The temperature at which a liquid boils and forms vapors is referred to as the:

A) boiling point
B) specific temperature
C) bubble point
D) dew point

Question 46

The Vapor Liquid Equilibrium diagram is primarily used for :

A) a condition or state where the rate of evaporation (liquid changing to vapor) equals the rate of condensation (vapor changing to a liquid).
B) A & C
C) visualizing a condition where a liquid and it's vapor (gas phase) are in equilibrium with each other.
D) components in a binary mixture exert partial pressures that are equal.

Question 47

The Reflux Ratio is best defined as :

A) the amount of overhead product returned to the column as reflux in relation to the amount of overhead taken off to storage.
B) careful control of column top temperature and product purity.
C) reflux rate divided by product rate
D) A & C