Janardan Rai Nagar Rajasthan Vidyapeeth 2006 B.Tech Chemical Engineering MASS TRANSFER OPERATIONS - I - Question Paper

Model Question Paper

BTCH1 MASS TRANSFER OPERATIONS - I

Time : 3 hrs Maximum marks : 75

 

Instruction:

1. Question paper is divided into Group A, Group B and Group C

2. Each Group is 25 Marks

3. Figure to the right in bracket indicates marks.

4. Good Handwriting is expected

5. Assume suitable data if necessary.

 

Group A (25 Marks)

 

Answer any three questions (Question 1 is compulsory)

	(5)

 

Q.1 Derive the equation for equimolal diffusion in gas.

(10)

Q.2 Discuss in detail about packing and packed tower design.

(10)

Q.3 a) What do you mean by cooling tower?

b) What are the types and explain any one in detail

Q.4 Explain any one equipment for stage contacts in detail?

(10)

Q.5 Writ about simple distillation and derive Rayleigh equation

	(10)

 

Group B (25 Marks)

 

Answer any three questions (Questions 6 is compulsory)

	(5)

 

Q.6 For the diffusion of solute A through a layer of gas to an absorbing liquid, with

Y_A = 0.20 and Y_Ai = 0.10. Calculate the transfer rate for one-way diffusion

(10)

compared to that of equimolal diffusion.

 

Q.7. A gas steam containing 30% A is passed through a packed column to remove 99% of

A by absorption in H₂0. Absorber will operate at 25⁰ C and 1 atmosphere and the gas

and liquid rates are to be 20mol / hft² and 100 mol / hft² respectively. Mass transfer

and equilibrium date are given below:

Y ^* = 3.1x at 25⁰C ; Kx^a = 60 mol/h ft³ unit mol fraction

Kx^a = 15 mol/h ft³ unit mol fraction

a)      Find N_oy, H_oy, Z _T assuming isothermal operation and neglecting changes in

gas and liquid flow rates. What percent of total resistance is in the gas phase?

b)      Calculate Z_T using N_ox and H_ox

 

(10)

Q.8 Flue gas at 320^oF and 1 atmosphere is to be cooled by a water spray. The gas

contains 14% CO₂ , 7% H₂0, 3% O₂ and 76% N_2.

Calculate adiabatic saturation temperature if the water spray enters at 80^oF

Repeat for water entering at T_S.

 

(10)

Q.9 Calculate the number of ideal stages using absorption factor method?

Q.10. Calculate the minimum number of plates Fenske Equation ?

 

 

(10)

 

Group C (25 Marks)

 

All Questions are Compulsory.

 

Q.11 Fill in the blanks ( each question carry 2 marks)

 

1. Molecular diffusion induced by temperature is thermal diffusion and that form an external field is called _______ .
2. Channeling is severe in towers packed with _______ .
3. ______ is the mass of vapor carried by a unit mass of vapor free gas.
4. For mass transfer to take place, streams entering each stage must not be in with one another__________ .
5. Rayleigh Equation is __________ .

 

Q.11 Multiple choice question. (Each question carry 2 marks)

 

1. Batch distillation is otherwise called as ________ .

a) Steam Distillation b) Flash Distillation c) Differntial Distillation

 

2. In a plate column ideal stages are also called________ .

a) Perfect plates b) Ideal Plates c) Real Plates

 

3. Humidity is measured by _______ .

a) Dew point method b) Both a & c c) Psychometric Method

 

4. Absorption factor A is given by __________ .

a) Mv / L b) L / mv c) Lm / v

 

5. Mass transfer caused by eddy motion is called _________ .

a) Molecular diffusion b) Eddy diffusion c) Momentum diffusion

 

Q.11 True or false (each question carry 1 marks).

 

1.                  Distillation is to separate liquid mixture of miscible and volatile substances into individual components by vapourisation.

2.                  In mass transfer operation, laminar flow is desired to increase mass transfer rate.

3.                  Packing provides large area of contact between liquid and gas.

4.                  Saturated gas is gas in which the vapor is in equilibrium with liquid at gas temperature.

5.                  The column above feed plate is called stripping section.

 

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