Indian Institute of Technology Kharagpur (IIT-K) 2008 M.Tech Chemical engineering Engineering aspects of aration and transport processes-2 - Question Paper
INDIAN INSTITUTE OF TECHNOLOGY, KHARAGPUR
Date of Examination:28/04/2008 (AN) Full Marks: 60
Mid spring Semester 2007-2008 Time: 3 hrs.
Subject Name: EASTP - II Subject No.: CH33006
Students: 3rd year BTech & Int. MTech in Chemical Engg. / Biotechnology
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Answer any four questions. Neat diagrams will earn credit. Data : Atomic weights - Mg=24.3; S=32; 0=16: H=1; Vapor pressure of water -______________ | ||||||||
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Property/ Component |
.n-hexane |
n-heptane |
n-octane |
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Liquid density', gm/cc |
0.659 |
0.679 |
0.703 |
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Mol. Wt. |
86.2 |
100.2 |
114.2 |
Ql.(a) Whats the AL law of crystal growth? < 1 mark>
(b) What are the three methods to create super-saturation in industrial crvstallizers? <1 mark>
(c) Why is a control on nucleation rate necessary in industrial crvstallizers? How is this implemented? <1+1=2 marks>
(d) Estimate the pressure in a vacuum crystallizer producing 5000 kg/hr MgSO.u 7H2O crystals from a feed having 31% MgSOj. The magma in the crystallizer is at 86 0 F and has 15% solids by volume. Boiling point elevation of the solution is small (~2F). <1 mark>
(e) Clearly mention (i) all assumptions of ideality in an ideal mixed suspension crystallizer and (ii) show' that the differential number-size distribution relationship has exponential nature. <2+8=10 marks>
1+1+2+1+10=15 marks]
Q2. Preliminary sizing of a packed towers for air drying using alumina balls have d=800 mm O, and h=1400 mm for the alumina packed bed. Two such towers (on? in operation, while the other is regenerated) operate to supply dry air continuously. The feed air is from a 6 6, 40 schedule pipe header.
(i) Draw the (a) schematic diagram of the system, showing all required piping, valves, measurements/instruments that you feel are necessary, (b) Provide 1 brief note explaining the working of the system to generate continuous dry' ai-stream. <4+3=7 marks>
(ii) Provide (a) a neat hand sketch of one tower with all its mechanical feature?. Extent of detailing should be sufficient to prepare a fabrication drawing fror.i the sketch i.e. it should contain appropriate labeling and dimensioning lines with the dimensions mentioned as *x mm etc. (b) Mention sizing basis ftr each mechanical detail. Also (c) show each nozzle location and nozzle orientations for the tower and mention the basis of sizing the nozzle. <4+2+2=8 marks>
[7+8=15 marks]
Q3. A flash drum is to be designed for 1000 kg/hr of liquid feed (30 mole% n-hexane, 45 mol % n-heptane, 25 mol % n-octane) flashing at almost atmospheric pressure and 80C and generating 60 mole % f feed) as vapor. The distribution coefficient (K=y/x) for the components are 2:18, 0.99 and 0.46. The design equation for sizing drum diameter is vmax (ft/sec)=0.35 x ((pi- pv)/pi)05, where pi and pv are the product liquid and vapor density (kg/m3) values, (i) Find the minimum area of the drum, and (ii) minimum factor of safety to be used in calculation of drum cross sectional area, apprehending that at times the drum temperature may go up to 99 C.
[10+5=15 marks]
Q4.(i) A solution of 2mo! % ethanol at its boiling point is to be stripped with live steam in a steam stripper. The stripped product must contain below 0.01 mol % ethanol. Find the number of sieve trays ( Ti0VCra = 65%) required in this column if the equilibrium relationship is expressed by y=9x, in this small zone of concentration change. <6 marks>
(ii) A distillation column has a side draw off. (a) Draw' and label the arrangements you require for this (chimney) draw off tray, (b) Explain the need for each mechanical feature in the drawing.<5+4=9 marks>
* [6+9=15 marks]
Q5 Answer following questions in brief:
(i) In a continuous distillation plant with feed preheating, there is always arrangement to recycle part or whole of the bottom stream (before cooling) to the feed pump suction. What is the use of this facility? <5 marks>
(ii) A 1 m3/hr stream of kerosene contains 10% v/v acetone. Acetone is miscible with water and water can be used as solvent to extract acetone from contaminated kerosene? (a) Suggest a complete process scheme to recover acetone ?i.nd re-use the water - provide a process flow diagram, (b) List all major equipment, (c) What will be considerations for selecting your extraction equipment? <3+t+l"5 marks>
(iu) Air (60 nm3/hr)to be supplied at 22 C to an electronics component plant needs to have 60% relative humidity in spite of variations in ambient temperature (13 - 46 C) and relative humidity (5 - 100%). Draw the flow diagram of a plant to supply this quality of air. Explain each step of the process with justification for including it. <5 marks>
[5+5+5=15 marks]
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Attachment: |
| Earning: Approval pending. |
