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Separation Process Flashcards

1
Q

Rose oil is extracted from rose leaves using ________ distillation

A

Steam distillation

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2
Q

When the solvent dissolves very little of solute then
A. large quantity of solvent is required to extract the solute
B. solvent of low latent heat of vaporization should be used
C. solvent of low freezing point should be used
D. very small quantity of solute is required

A

A. large quantity of solvent is required to extract the solute

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3
Q

The triangle whose one corner coincides with the enriching line and the outer corner is on the stripping line is called the

A

Feed plate

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4
Q

Flash distillation is suitable for the separation of components ________
A. having very close boiling points.
B. having very wide boiling points.
C. None of the above

A

B. having very wide boiling points.

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5
Q

Relative volatility varies with the concentration of component for an ideal solution. The relative volatility of a binary mixture may be defined as the ratio of vapor pressure of component ‘A’ to that of component ‘B’, when
A. liquid phase obeys Dalton’s law and vapor phase obeys Raoult’s law.
B. vapor phase obeys Dalton’s law and liquid phase obeys Raoult’s law.
C. only vapor phase follows Raoult’s law.
D. only liquid phase obeys Dalton’s law.

A

B. vapor phase obeys Dalton’s law and liquid phase obeys Raoult’s law.

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6
Q

Leaching of coarse solid lumps is also termed as

A

Percolation

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7
Q

Large scale usage of flash distillation is practiced in
A. petroleum refining
B. Soap manufacturing
C. ammonia synthesis plant
D. polymerization industry

A

A. Petroleum Refining

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8
Q

In an operating distillation column, the
A. driving force for the liquid flow is its specific weight.
B. driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column.
C. vapors and liquids are at their dew point and bubble point respectively
D. highest temperature is encountered at the top of the column.

A

B. driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column.

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9
Q

In case of steam distillation, the steam leaving the liquid is not completely saturated with distillate vapor, because
A. saturated steam is used for steam distillation.
B. temperature is less.
C. mixing of steam with the material being vaporized is not so intimate as to result in equilibrium condition.
D. total pressure is less.

A

C. mixing of steam with the material being vaporized is not so intimate as to result in equilibrium condition.

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10
Q

For a binary mixture distillation process, the degree of freedom is 2. However, if the pressure is fixed in this process, the number of independent variables in this process will be

A

3

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11
Q

Which of the following is the most suitable for extraction in a system having very low density difference?
A. Packed extraction tower
B. Centrifugal extractor
C. Pulsed extractor
D. Mixer-settler extractor

A

B. Centrifugal extractor

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12
Q

Total reflux in a distillation operation requires minimum
A. reboiler load
B. number of plates
C. condenser load
D. all of these

A

B. number of plates

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13
Q

In batch distillation with constant reflux, overhead product composition ________ with time.
A. Increase
B. Does not vary
C. Decrease

A

C. Decrease

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14
Q

Raoult’s law applies to the
A. non-ideal solution only.
B. all liquid solutions
C. solvents.
D. non-volatile solute.

A

C. Solvents

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15
Q

In distillation, overhead product contains
A. any number of components
B. two components
C. only one component
D. only saturated liquid

A

A. any number of components

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16
Q

For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will
A. Increase
B. Remain the same
C. Decrease

A

A. Increase

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17
Q

The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called

A

elutriation or elution

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18
Q

Pick out the wrong statement.
A. Even a forced draft cooling tower can not cool water below the wet bulb temperature.
B. Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column.
C. Different solids have different equilibrium moisture curves.
D. Total condenser or reboiler is considered equivalent to one theoretical plate in McCabe-Thiele method of theoretical plate calculation for distillation column.

A

B. Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column.

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19
Q

An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are being explored; (i) a reboiler is used and (ii) no reboiler is used but steam is fed directly to the bottom of the column. As compared to option (i), in option (ii)
A. more number of trays are required and the residue composition is more dilute in methanol.
B. less number of trays are required.
C. composition of the residue remains unchanged.
D. more number of trays are required but the residue composition remains unchanged.

A

B. less number of trays are required.

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20
Q

Ponchon-Savarit method analyses the fractional equipment based on
A. the assumption of constant molal overflow.
B. enthalpy balance only.
C. material balance only.
D. both enthalpy and material balances.

A

D. both enthalpy and material balances.

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21
Q

When the mixture to be distilled has a very high boiling point and the product material is heat sensitive, the separation technique to be used is _______ distillation.

A

Steam

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22
Q

The fixed cost of a distillation column at minimum reflux ratio is

A

Infinite

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23
Q

__________ extractor uses centrifugal force for separating the two phases.

A

A. Schiebel
B. Podbielniak
C. Treybal
D. None of these

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24
Q

In most of the mechanically agitated liquid-liquid extractors, baffles or horizontal compartmental plates are provided, which helps in
A. reducing the axial mixing.
B. maintaining the concentration difference between the two phases.
C. increasing the rate of extraction.
D. All of these

A

D. All of these

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25
Q

Which of the following applies to a feed at dew point?
A. 0 < f < 1
B. f > 1
C. f = 1
D. f = 0

A

C. f = 1

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26
Q

Pick out the wrong statement.
A. Decrease in Murphree plate efficiency is an indication of entrainment in distillation column.
B. The capacity of a distillation column is maximum at total reflux.
C. With increase in pressure, the solubility of gases in solvent increases at a fixed temperature.
D. In solvent extraction, the distribution coefficient should be as large as possible for solvent economy.

A

A. Decrease in Murphree plate efficiency is an indication of entrainment in distillation column.

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27
Q

The relative volatility of a binary mixture at the azeotropic composition is

A

Less than 1

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28
Q

Which of the following is not a continuous leaching equipment?
A. Bollman Extractor
B. Pachuka Tank
C. Kennedy Extractor
D. Hydrocyclones

A

B. Pachuka Tank

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29
Q

High pressure at the bottom of a distillation tower handling heat sensitive materials results in
A. increased relative volatility.
B. erosion of the tower.
C. thermal decomposition of bottoms.
D. very efficient operation.

A

C. thermal decomposition of bottoms.

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30
Q

For a binary mixture with low relative volatility, continuous rectification to get pure products will require
A. low reflux ratio
B. small cross-section column
C. high reflux ratio
D. less number of trays

A

C. high reflux ratio

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31
Q

In steam distillation, the
A. product must be immiscible with water.
B. temperature is 100°C.
C. temperature is higher than the boiling point of either component.
D. temperature is more than 100° C.

A

A. product must be immiscible with water.

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32
Q

A unit operation in which a soluble component is removed from an inert solid by a solvent which preferentially dissolves the soluble matter is known as

A

leaching

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33
Q

The unit operation by which soluble components of a liquid mixture are dissolved in a liquid immiscible with the insoluble component is

A

Solvent Extraction (or LLE)

34
Q

Tea percolation employs

A

leaching

35
Q

In a counter-current extractor, as the axial mixing increases, the extraction efficiency
A. increases
B. decreases
C. remains unchanged

A

B. decreases

36
Q

Bollman extractor
A. is a static bed leaching equipment.
B. is used for extraction of oil from oilseed.
C. is a centrifugal extractor.
D. employs only counter-current extraction.

A

B. is used for extraction of oil from oilseed.

37
Q

Radioactive nuclear waste is treated in
A. mixer-settler extractor
B. rotating-disc contactor
C. pulsed column extractor
D. Bollman extractor

A

C. pulsed column extractor

38
Q

Acetic acid will be most economically separated from a dilute solution of acetic acid in water by

A

Solvent extraction (LLE)

39
Q

Liquid-liquid extraction is based on the differences in

A

Solubility

40
Q

Which method is more efficient, a single large washing or repeated small washing?

A

repeated small washing

41
Q

A solution of solute (A) in diluent (B) is mixed with solvent (S). The component (B) is slightly soluble in (S). The resulting extract will be ____ in S, _____ in B, _____ in A (answer in rich or poor)

A

rich in S, poor in B, rich in A

42
Q

The solvent used in liquid extraction should not have high latent heat of vaporization, because
a. the pressure drop and hence the pumping cost will be very high.
b. it cannot be recovered by distillation.
c. its recovery cost by distillation may be prohibitively high.
d. it will decompose while recovering by distillation.

A

c. its recovery cost by distillation may be prohibitively high.

43
Q

Solvent extraction is the terminology applied to the liquid-liquid extraction, which is preferred for the separation of the components of liquids, when
a. extracting solvent is cheaply & abundantly available.
b. one of the liquid components is heat sensitive.
c. viscosity of liquid components is very high.
d. one of the liquid components has very high affinity towards the solvent.

A

d. one of the liquid components has very high affinity towards the solvent.

44
Q

In a counter-current liquid extractor
a. both liquids flow at fixed rate.
b. both liquids can have any desired flow rate.
c. only one of the liquids may be pumped at any desired rate.
d. liquid’s flow rate depends upon the temperature and pressure.

A

c. only one of the liquids may be pumped at any desired rate.

45
Q

A coalescer in a mixer-settler liquid-liquid extraction column
A. comprises of thin bed of substances of extended surface having high porosity.
B. helps in increasing the bubble size entering the settler.
C. helps in increasing the settling rate of the bubbles.
D. all of these

A

D. all of these

46
Q

Antibiotics are best handled in a
A. Podbielniak extractor
B. rotating disc contactor
C. sieve tray contractor
D. pulsed column extractor

A

A. Podbielniak extractor

47
Q

Which of the following solutions will follow Raoult’s law most closely?
A. A solution of benzene, toluene and oxylene
B. 35% solution of camphor in water
C. 35% solution of NH3 in water
D. A solution of polar organic compounds (not of homologs of a series).

A

A. A solution of benzene, toluene and oxylene

48
Q

Boiling point diagram is
A. not affected by pressure.
B. affected by pressure.
C. a plot of temperature vs. liquid composition.
D. a plot of temperature vs. vapor composition.

A

B. affected by pressure.

49
Q

The ease of difficulty of separating components by distillation is determined by the

A

relative volatility

50
Q

Strictly speaking, the relative volatility of most ideal binary solution is
A. not affected by temperature
B. greatly affected by temperature
C. slightly affected by temperature
D. greatly affected by pressure

A

B. greatly affected by temperature

51
Q

When the relative volatility of two miscible components is close to 1.00, the components can be separated by

A

extractive distillation

52
Q

The physical separation of components in a miscible mixture by simultaneous evaporation and condensation is

A

distillation

53
Q

In a batch distillation, the boiling point of the distillate product compared to the residue is (higher, lower, or the same)

A

lower

54
Q

Increasing the operating pressure of a distilling column
a. does not make a difference in components separation
b. makes separation difficult
c. sharpens separation
d. requires less heat in the feed heater

A

b. makes separation difficult

55
Q

One mole feed of a binary mixture of a given composition is flash vaporized at a fixed P and T. If Raoult’s law is obeyed, then changing the feed composition would effect
a. the product composition but not the fraction vaporized.
b. the product composition as well as the fraction vaporized.
c. the fraction vaporized but not the product composition.
d. neither the product composition nor the fraction vaporized.

A

c. the fraction vaporized but not the product composition.

56
Q

Steam distillation is used to
a. reduce the number of plates.
b. avoid thermal decomposition of a component.
c. increase the efficiency of separation.
d. increase the total pressure of distillation.

A

b. avoid thermal decomposition of a component.

57
Q

The amount of steam required per unit quantity of distillate in case of steam distillation will be reduced by
a. raising the temperature
b. lowering the total pressure
c. both (a) and (b)
d. neither (a) nor (b)

A

c. both (a) and (b)

58
Q

In distillation, the cooled liquid stream returned to the column to a cool plate or stage is called

A

reflux

59
Q

In a distilling column, the highest pressure will be at

A

the bottom

60
Q

A heat transfer equipment to convert vapor to liquid is a/an

A

condenser

61
Q

A reboiler provides heat to the

A

bottom of the column

62
Q

The temperature in distilling column, from bottom to top

A

decreases

63
Q

The theoretical minimum reflux ratio in distillation column is attained if the column has __________ number of plates

A

infinite number of plates

64
Q

If x co-ordinate of intersection point of feed line and rectifying sections operating line on equilibrium curve is same as the mole fraction of more volatile components in the feed, then the quality of feed is

A

saturated liquid

65
Q

As the reflux ratio decreases, the
a. separation becomes more efficient.
b. number of plates increases.
c. column diameter increases.
d. none of these.

A

b. number of plates increases.

66
Q

In a distillation column, with increase in the reflux ratio, the heat removed in the cooler

A

increases

67
Q

Fenske’s equation for determining the minimum number of theoretical stages in distillation column holds good, when the
a. relative volatility is reasonably constant.
b. mixture (to be separated) shows negative deviation from ideality.
c. mixture (to be separated) shows positive deviation from ideality.
d. multicomponent distillation is involved.

A

a. relative volatility is reasonably constant.

68
Q

Inside the distillation column, the
a. driving force for the vapor flow is the pressure drop.
b. liquids are not always at their bubble points.
c. pressure increases gradually from bottom to the top of the column.
d. none of these

A

a. driving force for the vapor flow is the pressure drop.

69
Q

On moving the feed line (q-line) from saturated liquid feed (vertical position) to saturated vapor feed (horizontal feed), if the slope of both the operating lines are to be increased, then it will result in
a. greater degree of separation with a fixed number of trays
b. increased reboiler load
c. increased reflux ratio
d. none of these

A

c. increased reflux ratio

70
Q

In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of
a. area between operating line and 45° diagonal x-y diagram
b. condenser and reboiler surfaces
c. tower cross-section
d. none of these

A

a. area between operating line and 45° diagonal x-y diagram

71
Q

Overall efficiency of the distillation column is
a. the ratio of number of ideal plates to actual plates
b. the ratio of number of actual plates to ideal plates
c. same as the Murphree efficiency
d. always more than the point efficiency

A

a. the ratio of number of ideal plates to actual plates

72
Q

Pick out the correct statement.
a. Ponchon-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of non-ideal binary system by distillation.
b. A sharp decrease in pressure drop is an indication of flooding in a distillation column.
c. Solvent used in extractive distillation should be of high volatility.
d. Flash distillation is suitable for separating components which have very close boiling temperature.

A

a. Ponchon-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of non-ideal binary system by distillation.

73
Q

Pick out the correct statement.
a. The slope of the stripping line is always less than unity.
b. For a given separation in a binary distillation column, with increase in reflux ratio (above the minimum reflux ratio), the fixed cost of the distillation column first increases and then decreases.
c. In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux.
d. Kremsor-Brown-Souder’s equation is used to calculate the efficiency of a plate tower.

A

c. In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux.

74
Q

Design calculation for multiple component distillation is done by
a. Ponchon-Savarit method
b. Mccabe-Thiele method
c. enthalpy concentration method
d. tray to tray calculations

A

d. tray to tray calculations

75
Q

Pick out the wrong statement:
a. Reboiler is not used in open steam distillation.
b. The separation of solutes of different molecular sizes in a liquid solution by use of a suitable membrane is called dialysis.
c. Freeze drying is used for the drying of fish.
d. Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition.

A

d. Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition.

76
Q

In extractive distillation, solvent is
a. added to alter the relative volatility of the mixture.
b. of high volatility.
c. present in overhead stream.
d. of high viscosity to give high tray efficiency.

A

a. added to alter the relative volatility of the mixture.

77
Q

Solvent used in extractive distillation
a. is of low volatility.
b. forms a low boiling azeotrope.
c. forms a high boiling azeotrope.
d. does not alter the relative volatility of the original components.

A

b. forms a low boiling azeotrope.

78
Q

Azeotropic distillation is employed to separate
a. constant boiling mixture
b. high boiling mixture
c. mixture with very high relative volatility
d. heat sensitive materials

A

a. constant boiling mixture

79
Q

The equilibrium liquid composition compared to the vapor composition in case of azeotropic mixture is
a. more
b. less
c. same
d. either more or less; depends on the system

A

c. same

80
Q

Pick out the wrong statement.
a. The mole fraction of solute is directly proportional to the molality of a ‘dilute’ solution.
b. For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is nonlinear in the case of steady state unimolal unidirectional diffusion.
c. Azeotropes obey Raoult’s law at all temperature.
d. The relative volatility of a binary mixture at the azeotropic composition is 1.

A

c. Azeotropes obey Raoult’s law at all temperature.

81
Q

Pick out the system with minimum boiling azeotrope at 1 atm.
a. benzene-toluene
b. ethyl alcohol-water
c. hydrochloric acid-water
d. all of these

A

b. ethyl alcohol-water

82
Q

Which of the following binary systems is an example of a maximum boiling azeotrope?
a. water-hydrochloric acid
b. acetone-carbon disulfide
c. water-ethyl alcohol
d. n-heptane-n-octane

A

a. water-hydrochloric acid

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