In a packed tower, the value of HETP equals HTUOG, when the equilibrium and the operating lines are (where, HETP = height equivalant to a theoretical plate HTUOG = overall gas phase height of a transfer unit)

H₂S is being absorbed in a gas absorber unit. The height of the transfer unit based on the overall mass transfer coefficient on the gas side is 0.4 m. The equilibrium data is given by, y = 1.5x. The bulk concentration of H₂S has to be reduced from 0.05 to 0.001 mole fraction in the gas side. The height of the tower (in metres) corresponding to an operating line given by, y = 5x + 0.001 is

A

2.0

B

1.56

C

1.0

D

0.56

In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTU_OG __________ the absorption factor.

A

Increases with increase in

B

Is one at unity value of

C

Both A and B

D

Neither A nor B

For the gas absorption, the height of a transfer unit, based on the gas phase is given by (G: superficial molar gas velocity, L: superficial molar liquid velocity, F_G: mass transfer co-efficient, mols/m², a: in-terfacial area per unit volume of tower)

A

$$\frac{{\text{G}}}{{{{\text{F}}_{\text{G}}}.{\text{a}}}}$$

B

$$\frac{{{{\text{F}}_{\text{G}}}}}{{{\text{G}}{\text{.a}}}}$$

C

$$\frac{{{\text{G}}{\text{.a}}}}{{{{\text{F}}_{\text{G}}}}}$$

D

$$\frac{{\text{L}}}{{{{\text{F}}_{\text{G}}}.{\text{G}}}}$$

In a wetted-wall tower, an air-H2S mixture is flowing by a film of water which is flowing as a thin film down a vertical plate. The H2S is being absorbed from the air to the water at a total pressure of 1.50 atm abs and 30oC. The value of kc of 9.567×10-4 m/s has been predicted for the gas-phase mass-transfer coefficient. At a given point the mole fraction of H2S in the liquid at the liquid-gas interface is 2.0×10-5 and pA of H2S in the gas is 0.05 atm. The Henry’s law equilibrium relation is pA(atm) = 609xA (mole fraction in liquid). Calculate the rate of absorption of H2S.

A

1.480×10-3 kmol/m2.s

B

1.486×10-3 kmol/m2.s

Find the absorption tower height if Number of gas phase transfer units 4.09 Height of gas phase transfer units 1.5 meters

A

2.72 meters

B

0.36 meters

C

6.135 meters

D

None of the mentioned

At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid __________ that in dry packed tower.

A

Is greater than

B

Is lower than

C

Is same as

D

Cannot be predicted as data are insufficient

What is the overall height of gas transfer unit if the volume is 1000m 3 and the overall gas phase coefficient is 2.6 and the inside cross sectional area is 20m 2 .

A

12m

B

13.6m

C

18.9m

D

19.2m

What is the overall height of gas transfer unit if the volume is 780m 3 and the overall gas phase coefficient is 4.2 and the inside cross sectional area is 45m 2 .

A

4.1m

B

7.2m

C

10.4m

D

19.2m

What is the overall height of gas transfer unit if the volume is 489m 3 and the overall gas phase coefficient is 1.2 and the inside cross sectional area is 22m 2 .

A

12m

B

13.6m

C

18.5m

D

19.2m

Kelly and Chris packed several boxes with books. If Chris packed 60 percent of the total number of boxes, what was the ratio of the number of boxes Kelly packed to the number of boxes Chris packed?

A

1 to 6

B

1 to 4

C

2 to 5

D

2 to 3

In a packed tower, the value of HETP equals HTU_OG, when the equilibrium and the operating lines are (where, HETP = height equivalant to a theoretical plate HTU_OG = overall gas phase height of a transfer unit)

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