Chemical Engineering - Mass Transfer

21. 

An alkaline solution is used to reduce the concentration of carbon dioxide in a stream from 10% to 0.1% by absorption with irreversible chemical reaction. The overall number of transfer units based on gas phase is

A. 9.21
B. 4.605
C. 100
D. 0.001

Answer: Option B

Explanation:

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22. 

HETP is numerically equal to HTU, only when the 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: Option C

Explanation:

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23. 

In a distillation operation, what is the effect of the temperature of the reflux stream (given below) on the condenser and reboiler loads ?
Reflux conditions:
(i) Reflux stream is completely liquid and is at its bubble point.
(ii) Reflux stream is below its bubble point.

A. Condenser and reboiler loads are the same in both the cases.
B. Reboiler load is the same in both the cases but condenser load is higher in case (ii).
C. Condenser load is the same in both the cases but reboiler load is higher in case (ii).
D. Both condensor and reboiler loads are higher in case (ii) as compared to case (i).

Answer: Option D

Explanation:

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24. 

Steady state equimolal counter diffusion occurs in case of

A. leaching
B. absorption
C. binary phase distillation
D. liquid-liquid extraction

Answer: Option C

Explanation:

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25. 

JD factor for mass transfer is a function of Reynolds number. Mass transfer by molecular diffusion from a single drop to surrounding still air is given by

A. Nsh = 2
B. Nst = 2
C. Nsc = 2
D. none of these

Answer: Option A

Explanation:

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