**B.E. (Petrochemical Engg.)**

**NOVEL SEPARATION PROCESSES (Sem. – I)(2008 Pattern) (Elective – I)**

Time :3 Hours] [Max. Marks :100

Instructions to the candidates:-

** 1) **Answer any 03 questions from each section.

** 2) **Answers to the two sections should be written in separate books.

** 3) **Neat diagrams must be drawn wherever necessary.

** 4) **Pigures to the right indicate full marks.

** 5) **Use of logarithmic tables slide rule, Mollier charts, electronic pocket calculator and steam tables is allowed.

** 6) **Assume suitable data if necessary.

SECTION – I

QIA a) Discuss in detail the selection criteria for separation processes by giving suitable examples. [8]

b) Discuss in detail the energy requirements for separation processes by giving suitable examples. [10]

OR

Q2) Attempt Any Three of the following : [18]

a) Explain in brief the basic process principles involved in Reverse Osmosis. State the industrial applications.

b) Compare and contrast on Macroemulsions and Microemulsions with suitable examples.

c) Discuss the process principles involved in Ultrafiltration and Nanofiltration.

d) Draw concentration profiles for membrane processes for following cases:

i) Two liquid films and a solid and,

ii) Two gas films and a solid

Write down the final flux equations for above cases?

Q3) Derive the model equation for Complete mixing model for gas separation by membranes. Discuss the solution strategy for the model equations. [16]

Q4) a) A 9 – micron tubular membrane is used to recover salt A from a dilute solution. The solutions to either side are at 0.025 and 0.0045 kmol/m^{3}, with mass transfer coefficients of 3.75 10 ^{s} and 2.5 x 10 ^{s} m/s respectively. The distribution coefficient is 0.85 and the diffusivity of A in the mambrane is 275 x 10-^{11} m^{2}/s. [10]

i) Calculate the percentage of total resistance to mass transfer contributed by the membrane.

ii) Calculate the membrane area needed to allow recovery at 0.015 kmol/hr.

Flow inside the tube is turbulent and mass transfer follows the Gilliland, Sherwood 8 Linton correlation. If the velocities of both solutions are doubled, what will the membrane resistance now be

b) Reverse osmosis of salt solution at 25^{0}C is tested with a 5. x 10^{3} m^{2} cellulose acetate membrane. On one side of the membrane is 1 mol NaCl/kg H_{p}O solution at 60 atmospheres (abs.) pressure, on the other is 0.01 mol NaCl/kg H_{p}O at atmospheric pressure. The permeation rate is 96.12 ml/hour. Find the solvent permeability and the rejection rate. [6]

Q5) Discuss in detail various membrane modules with neat sketches. State its applications in different types of membrane separation processes. [16]

OR

Q6) A liquid containing dilute solute A at a concentration 3.3 x 10 ^{2} kgmol/m^{3} is flowing rapidly by a membrane of thickness, 3 x 10 ^{s} m. The solute diffuses through the membrane and its concentration on the other side is 0.55 x 10 ^{2} kgmol/m^{3}. The mass transfer coefficient k is large and can be considered as infinite and k „ = 2.22 x 10 ^{s} m/s.

c2

Data : Distribution coefficient = K’ = 1.5 and Diffusivity, D_{AB} = 6 x 10 ^{11} m^{2}/sec in the membrane.

a) Derive the equation to calculate the steady state flux, NA and make a sketch.

b) Calculate the flux and concentration at the membrane interfaces. [16]

SECTION – II

Q7) Discuss in detail the process principles involved in Pressure Swing Adsorption (PSA) and Temperature Swing Adsorption (TSA) with industrial applications. [18]

OR

Q8) Nitrogen gas contaminated with water at 975 mg per kg of N_{2} is continuously fed to a pilot – scale adsorption column that contains a 0.250 m high bed packed with molecular sieve. Outlet data were as follows :

Time (hours) |
0 |
9 |
9.2 |
9.6 |
10.0 |
10.4 |
10.8 |
11.25 |
11.5 |
12.0 |
12.5 |
12.8 |

Water Conc. (mg/kg N_{2}) |
0 |
0.6 |
2.6 |
21 |
91 |
235 |
418 |
630 |
717 |
855 |
906 |
926 |

If break – through is defined here as being when c/c_{Q} reaches 0.02, find the following : [18]

a) Break throughtime.

b) Height of “zone” of unspent (but not unused) bed in column

c) Fraction of total sieve capacity used by breakthrough time.

d) Break through time if an industrial column were to be built of the same cross – section, but with a bed height of 0.6m

Q9) a) From Darcy’s Law, the velocity through a packed bed for a given pressure

^Pd^{2}p

drop (P) is given by : u – ———-

lr|

Where,

9 = Darcy’s constant P = Pressure drop d = Particle diameter

^{p}

l = Length of column n = Viscosity of the mobile phase

Also, from the analysis of the Van Deemter equation, for a well packed column and for a highly retained solute, it is found that :

H . = 2.48d

mm p

and the velocity at H is equal to

^{J} mm

1.62D

Where D_{m} is the diffusivity of the solute in the mobile phase.

From the above informations, derive an analytical expression for the maximum efficiency obtainable for a column in terms of these parameters, if the maximum allowable pressure drop is P. [8]

b) In gas chromatography, a plot of HETP as a function of the mobile phase velocity is described by the Van Deemter equation :

HETP = A + B/u + Cu

Physically, what do the terms A, B and C represent? Calculate the optimum value of the mobile phase velocity and the plate height in terms of these parameters. [8]

OR

Q10) a) The retention ratio in chromatography is defined as :

^{R}=w

Show that R is related to the capacity factor, given by equation :

R = 1/ k + 1 [8]

b) Discuss the process principles involved in elution chromatography and derive the retention equation. [8]

QII) Write short notes on [16]

a) Parametric Pumping.

b) Reactive Separations.

c) Isoelectric Focusing.

d) Bioseparation.

OR

Q12) Define the following terms in connection with chromatographic separations and give appropriate equations : [16]

a) Partition coefficient (K)

b) Retention Volume (V_{R})

c) Retention Ratio (R)

d) Capacity factor (K)

e) Separation factor (a)

f) Resolution (R_{s})

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