Mass Transfer Operation - 2 - May 2016
MU Chemical Engineering (Semester 6)
Total marks: --
Total time: -- INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary 1(a) Define q factor is distillation and give its significance. 4 marks
1(b) Discuss the selection criteria for solvent liquid-liquid extraction. 4 marks
1(c) Explain the factors affecting leaching operation. 4 marks
1(d) Give the properties of adsorbents. 4 marks
1(e) State and explain the &Delta 4 marks
2 For a binary system of heptane-ethylbenzene the equilibrium data are as follows:
A feed mixture composed of 42 mole% heptane and 58 mole% ethyl benzene is to be fractionated to yield an overhead product of 197 mole% heptane and a residue of 99 mole ethyl benzene.
(i) Using reflux ratio of 1.5 find the number of equilibrium stages needed for saturated liquid feed and a bubble point reflux by the McCabe-Thiele method.
(ii) Find the minimum reflux ratio.
(iii) Find the number of equilibrium stages at total reflux. 4 marks
3(a) Give the procedure to find the height of packed bed for liquid-liquid extraction tower. 4 marks
3(b) Derive Fenske's equation for minimum no. Of stages at total reflux. 4 marks
4(a) Explain the construction and working of Bollmann extractor. 4 marks
4(b) For extraction of dioxane from water, benzene is used as an extraction solvent. At 298K, the equilibrium distribution of dioxane between water and benzene is as given below:
|Weight % dioxane in water||5.1||18.9||25.2|
|Weight % dioxane in benzene||5.2||22.5||32|
At these concentrations, water and benzene are substantially insouluble 1000kg of solution containing 25% dioxane is to be extracted with benzene to remove 95% of the dioxane free benzene is used.
(i) calculate the solvent requirement for single batch operation.
(ii) If the extraction were done: in four stages cross current unit using 750 kg of pure benzene each time, determine the final raffinate concentration and the percentage removal of dioxane from feed solution. 4 marks
5(a) Discuss the adsorption in fixed beds. Explain break through curve and adsorption zone. 4 marks
5(b) A hot solution of 5000kg containing Na2CO3 and water with a concentration of 25% by weight Na2CO3 is cooled to 20° 4 marks
Write short notes on any Four out of following6(a) Minimum and maximum boiling azeotropes. 4 marks
6(b) Ion Exchange 4 marks
6(c) Hollow and spiral wound membranes 4 marks
6(d) Reverse osmosis 4 marks
6(e) Oslo cooling crystallizer 4 marks