Mass Transfer Operations I — Winter 2020

Discuss the factors affecting choice of separation method.

Differentiate between packed towers/tray towers.

Discuss in detail classification of mass transfer operations with examples.

Explain mass transfer operation between two immiscible phases.

Explain material balance for single stage leaching.

Methane diffuses at steady state through a tube containing helium for the case equimolar counter diffusion. At point 1, the partial pressure of methane is 55 kPa and at point 2, 0.03 m apart is kPa. The total pressure is 101.325 kPa and temperature is 298 k, at this temperature and pressure the value of diffusivity is 6.75 × 10-5 m2/s. Calculate the partial pressure of methane at point 0.02 m apart from point 1 for the above case.

Define selectivity, absorption factor and ideal stage.

Explain mass, heat and momentum transfer analogies.

Explain the following terms with respect to tray towers:

Flooding (ii)Priming (iii) Coning (iv)Weeping (v) Dumping (vi)Tray Spacing (vii)Theoretical Tray

Differentiate between random and regular packing.

Define liquid extraction giving typical example. Explain equilateral–triangular co-ordinate and the mixture rule.

Explain selection criteria for choice of solvent for gas absorption.

With neat diagram discuss Venturi Scrubber.

Discuss local and overall mass transfer coefficients.

Derive equations to calculate rate of steady state diffusion of ‘A’ through non-diffusing ‘B’ and also for steady state equimolal counter diffusion in case of gases.

Explain counter current multiple contact, Shanks system for leaching.

Discuss in detail about Film theory for mass transfer coefficient.

Enlist different industrial liquid extractors and explain any one in detail with neat figure.

Explain preparation of solids for leaching.

Discuss agitated batch crystallizer with neat sketch.1

Ahot solution containing 2000kg of MgSO4 and water at 57OC and with a concentration of 30 weight% MgSO4 is cooled to 30⁰C and MgSO4.7H2O crystals are removed. The solubility at 30⁰C is 35.5 kg MgSO4 per100 kg water. Calculate the yield of crystals and % yield of crystallization. Assume that no water is vaporized. Atomic weight: Mg=24, S=32, O=16, H=1

Explain caking of crystals and methods to prevent it.

Define super saturation and explain Meir’s super saturation theory. Explain stages of crystallization. Explain stages or mechanism of crystallization.

Discuss the system of three liquids- one pair partially soluble and the effect of temperature on ternary equilibria.