Gas Absorption

Question 1

For absorbing a sparingly soluble gas in a liquid, the
a.) gas side coefficient should be increased
b.) liquid side coefficient should be increased
c.) gas side coefficient should be decreased
d.) liquid side coefficient should be decreased

Answer 1

B

Question 2

For contacting a highly soluble gas with a liquid
a.) bubble the gas through liquid
b.) spray the liquid on gas stream
c.) either a or b will suffice
d.) none of them

Answer 2

A

Question 3

Wetted wall tower experiment determines
a.) molal diffusivity
b.) volumetric coefficient
c.) mass transfer coefficient
d.) none of these

Answer 3

C

Question 4

Stacked packing compared to dumped packing
a.) provides poorer contact between the fluids
b.) gives lower pressure drop
c.) both (a) and (b)
d.) gives higher drop

Answer 4

C

Question 5

Channeling is most severe
a.) in towers packed with stacked packing
b.) in towers packed randomly with crushed solids
c.) in dumped packing of regular units
d.) at very high liquid flow rate

Answer 5

A

Question 6

Flooding results in
a.) High tray efficiency
b.) Low tray efficiency
c.) High gas velocity
d.) at very high liquid flow rate

Answer 6

B

Question 7

Operating velocity in a packed tower is usually
a.) half the flooding velocity
b.) twice the flooding velocity
c.) equal to flooding velocity
d.) more than the flooding velocity

Answer 7

A

Question 8

At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid
a.) is greater than that in a dry packed
b.) lower than that in drying packing
c.) is same as that in drying packing
d.) cannot be predicted as data are insufficient

Answer 8

A

Question 9

Berl saddle made of carbon cannot be used
a.) for alkalis
b.) for SO2
c.) for H2SO4
d.) in oxidizing atmosphere

Answer 9

D

Carbon is not suitable coz it is itself an element that can be oxidized.

Question 10

Flooding in a column results due to
a.) high pressure drop
b.) low pressure drop
c.) low velocity of the liquid
d.) high temperature

Answer 10

A

Question 11

The operating line for an absorbed is curved when plotted in terms of
a.) mole fractions
b.) mole ratios
c.) partial pressure
d.) mass fraction

Answer 11

C

Question 12

In case of an absorber, the operating
a.) line always lies above the equilibrium curve
b.) line always lies below the equilibrium curve
c.) line can be either above or below the equilibrium curve
d.) velocity is more than the loading velocity

Answer 12

A

Question 13

13. For an absorber, both equilibrium and operating line will be straight for
    a.) concentrated solution and non-isothermal operation
    b.) dilute solution and non-isothermal operation
    c.) dilute solution and isothermal operation
    d.) concentrated solution and isothermal operation

Answer 13

C

Question 14

In case of desorber (stripper)
a.) the operating line always lies above the equilibrium curve
b.) the operating line always lies below the equilibrium line
c.) temperature remains unaffected
d.) temperature always increases

Answer 14

B

Question 15

The minimum liquid rate to be used in an absorber corresponds to an operating line
a.) of slope = 1
b.) of slope = -1
c.) tangential to the equilibrium curve
d.) none of these

Answer 15

C

Question 16

Absorption factor is defined as
a.) slope of the equilibrium curve/slope of the operating line
b.) slope of the operating line/slope of the equilibrium curve
c.) slope of the operating line - slope of the EC
d.) slope of the OL * slope of the EC

Answer 16

B

Question 17

H2S present in naptha reformed gas is removed by absorbing with
a.) ethanolamine
b.) K2CO2
c.) HCL
d.) vacuum gas soil

Answer 17

A

Question 18

If G = insoluble gas in gas stream and L = non-volatile in liquid stream, then the slope of the operating line for the absorber is
a.) L/G
b.) G/L
c.) always < 1
d.) none of these

Answer 18

A

Question 19

Raschig rings made of porcelain cannot be used for treating
a.) concentrated hydrochloric acid
b.) concentrated nitric acid
c.) alkalis
d.) concentrated sulfuric acid

Answer 19

C

Porcelain is susceptible to chemical attack by strong bases.

Question 20

For absorbers, high pressure drop results in
a.) increased efficiency
b.) decreased efficiency
c.) high operating cost
d.) better gas liquid contact

Answer 20

C

Question 21

21. Which of the ff is an undesirable property for an absorbing solvent?
    a.) low vapor pressure
    b.) low velocity
    c.) freezing point
    d.) none of these

Answer 21

D

Question 22

22. Out of the ff properties of a solvent for absorption, which combination of properties provides a good solvent?
    I. high viscosity II. Low viscosity
    III. high vapor pressure IV. Low vapor pressure
    V. high gas solubility VI. High freezing point
    VII. low freezing pointa.) II, IV, V, VII
    b.) I, IV, V, VI
    c.) II, IV, V, VI
    d.) I, IV, V, VII

Answer 22

A

Question 23

23. When both the fluids flow concurrently in an absorber, the slope of the operating line is
    a.) negative
    b.) positive
    c.) I
    d.) -1

Answer 23

A

Question 23

23. When both the fluids flow concurrently in an absorber, the slope of the operating line is
    a.) negative
    b.) positive
    c.) I
    d.) -1

Answer 23

A

Question 24

24. Ammonia present in the coke oven gas is removed by washing with a.) caustic solution b.) dilute ammoniacal liquor c.) dilute HCl d.) ethanolamine

Answer 24

B

Question 25

25. Which of the following is not fixed by process requirements in the design of absorbers? a.) flow rate of the entering gas b.) composition of the entering liquid c.) terminal concentration of gas stream d.) none of these

Answer 25

D

Question 26

26. In an absorber, HETP does not vary with a.) flow rate of liquid b.) flow rate of gas c.) type and size of packing d.) none of these

Answer 26

D

Question 27

27. Which of the ff is an undesirable property in a low-packing a.) large surface per unit volume b.) large free cross section c.) low weight per unit volume d.) large weight of liquid retained

Answer 27

D

Question 28

28. Very tall packed towers are divided into series of beds to a.) reduce the overall pressure drop b.) avoid channeling c.) reduce liquid hold-up d.) avoid flooding

Answer 28

B

Question 29

29. For the same system, if the same liquid used in an absorber is decreased, the tower height will a.) increase b.) decrease c.) remain unaffected d.) decrease or increase depends on the type of liquid

Answer 29

A

Question 30

30. HETP is numerically equal to HTU only when operating line a.) lies below the equilibrium line b.) lies above the equilibrium line c.) and equilibrium lines are parallel d.) is far from the equilibrium line

Answer 30

C

Question 31

31. Desirable value of absorption factor in an absorber is a.) 1 b.) <1 c.) >1 d.) 0.5

Answer 31

C

Question 32

32. Absorption accompanied by heat evolution results in a.) increased capacity of the absorber b.) increase in equilibrium solubility c.) decrease in equilibrium solubility d.) none of these

Answer 32

C

Question 33

33. Co-current absorbers are usually used when the gas to be dissolved in the liquid is a.) sparingly soluble b.) highly soluble c.) a pure substance d.) a mixture

Answer 33

C

Question 34

34. Channeling in a packed tower results from a.) high pressure drop b.) maldistribution of liquid c.) non-uniformity of packing d.) both b and c

Answer 34

D

Question 35

35. Diameter of raschig rings used in packed tower in industry is normally around a.) 2" b.) 8" c.) 12" d.) 18"

Answer 35

A