IFS - Indian Forest Service Chemical Engineering Previous Year Paper (2001)
PAPER - I : SECTION A
1. Answer any four of the following (10 x 4 = 40)
(a) Explain free settling and hindered settling. What is the functional relationship between terminal velocity and particle size?
(b) What are enthalpy-concentration diagrams? How do you construct it?
(c) What do you understand by primary nucleation and secondary nucleation during crystallization?
(d) Explain critical thickness of insulation. How do you find it for cylindrical shapes? Assume the thermal conductivity of the insulation as k. Heat transfer coefficient is h.
(e) Define the following:
(i) Mixing index for granular solids
(iii) Relative volatility
2. Answer the following: (10 × 4 = 40)
(a) Explain briefly about random packings used in packed towers. What are the characteristics considered during their selection?
(b) Differentiate between skin drag and form drag. Where do they exist and under what conditions?
(c) Describe the differential and cumulative screen analyses.
(d) Compare the venturi meter and orifice meter.
3. (a) Derive the Fenske equation to calculate the minimum number of plates in distillation. (20)
(b) Explain a mixer-settler extraction system. (10)
(c) Discuss the experimental measurement of diffusivity in a binary system. (10)
4. (a) Estimate the heat transfer coefficient using available empirical correlation for the following case:
A lubricating oil is flowing through a long smooth tube of 25 mm inside diameter. The inlet and outlet oil temperatures are 21°C and 55°C. The average wall temperature is assumed to be 65°C.
The Reynolds number for the prevailing flow conditions has been found to be 10020.
Data : At the average temperature, oil has Viscosity = 31 cp
Specific heat = 1.88 kJ/kg K
Specific gravity = 0.91
Thermal conductivity = 0.123 W/m K
Viscosity at 65°C = 12 cp
Any missing data may be suitably assumed with justification. (20)
(b) Discuss the method of estimation of the radiant heat duty of an oil fired furnace. (10)
(c) Describe the different methods of feeding a multiple effect evaporator. (10)
5. Answer any four of the following: (10 × 4 = 40)
(a) Explain about ultra filtration.
(b) Write briefly on the dielectric method of level measurement.
(c) Write the stepwise procedure for the design of a 2: 1 elliptical head.
(d) Describe the flapper-nozzle assembly used in process control.
(e) Describe the procedure for the design of sampled data controllers.
6. (a) For membrane processes, explain about (15)
(i) Dependence of permeability on temperature and its prediction
(ii) Membrane selectivity
(b) Explain about the following: (15)
(i) Commercial dialyzers
(ii) Membranes for dialysis
(c) What is Pervaporation? Elaborate. (10)
7. A flat-bottomed vertical cylindrical tank having a conical roof is to be designed for storing a petroleum product having a specific gravity of 0.8. The capacity of the storage tank should be 250 m3. Assume height to diameter ratio as unity. The width of the plate to be used for each course is 1.8 m. The allowable stress value of the material of construction is 14 kg/mm2. Assume a weld joint efficiency factor of 0.85. Determine the thickness required for each course of the cylindrical shell of the storage tank. (40)
8. Answer the following: (10 × 4 = 40)
(a) Describe the electromagnetic flow meter. What are their advantages and limitations?
(b) Find the frequency response (AR and phase angle) of a proportional + integral controller. Give a sketch of the Bode diagram of the same.
(c) Write briefly on Feed forward control.
(d) What axe the elements of a computer control system? Explain briefly
PAPER-II : SECTION A
1. Answer any four of the following
(a) Distinguish between adiabatic flame temperature and actual flame temperature. (10)
(b) What is Joule-Thomson coefficient and what is inversion point? Sketch the isenthalpic curves for a gas and show the inversion curve and explain the significance of Joule-Thomson coefficient. (10)
(c) Define effectiveness factor. On what parameters does the effectiveness parameter of a first order reaction depend? What is meant by the regime of strong pore resistance? (10)
(d) What is an azeotrope? Draw the P-X-Y and T-X-Y diagrams for maximum boiling and for minimum boiling azeotropes. What kind of azeotrope a system is likely to form if it exhibits large positive deviations from Raoults law? (10)
(e) What are performance equations of different reactors? Derive the performance equation for a plug flow reactor operating at steady state conditions? How would you graphically represent these performance equations? (10)
2. A hydrocarbon fuel of unknown composition is burned with air and the volumetric composition of the resulting combustion products on dry basis is CO2 = 7.26% CO = 2.42%, O2 = 7.5% and N2 = 82.82%, Determine the composition of the fuel on mass basis and the per cent excess air used for combustion. (40)
3. Industrial grade methanol is produced according to the reaction CO(g) + 2H2 (g) → 4 H3 OH(g).
Assuming that the reaction mixture attains a state of equilibrium. Estimate the degree of conversion at 500 K and 5 bar pressure. The enthalpy of vaporization of CH3 OH at 298.15 K is 37.988 kJ/mol. The saturation pressure of CH3OH at 298.l5 K is 0.l67l6 bar. The isobaric molar heat capacities of the reactants and products are expressed as Cp= a + bT = cT2 where, C is in kJ/mol K and T is in K. For CH3 OH (1) it is known that ΔH°f298 = -238.648 kJ/mol and ΔG°f296 = -166.215 kJ/mol. (40)
Substance a b × l03 c × 106 ΔH0 f298 (kJ/mol) ΔG°f298 (kJ/mol)
CO(g) 28.07 4.63 — -110.532 -137.327
H2(g) 27.01 3.51 — — —
CH3OH(g) 18.38 101.56 -28.68 — —
4. What is autocatalytic reaction? How do you calculate the conversion X of a reactant at a given time t? Derive the required expression assuming the initial concentration of reaction A to be CA0. Which reactor arrangement would you suggest for obtaining the highest achievable conversion? Explain using a rate-concentration curve. (40)
5. Answer any four of the following :—
(a) What is coking? What are the different coking processes employed in the industry? Discuss in brief, the basic process variables, which contribute to the quality and yields of Delayed Coking products. (10)
(b) What are the major engineering problems faced in fermentation processes? Enumerate the different methods for the production of ethyl alcohol. Describe in brief the process of production of ethyl alcohol by fermentation. (10)
(c) What are the various factors which should be considered while making a feasibility survey of a proposed design project? (10)
(d) What is acid rain and what are the possible causes for it? Elaborate on the adverse effects of acid rain. (10)
(e) What is meant by Ozone depletion? Describe the various Ozone destruction cycles in brief. How is the presence of Ozone in the stratosphere beneficial? (10)
6. How would you define cement? List the various types of port land cement along with their characteristic properties and composition. Describe in detail, with the help of a neat flow sheet, the process of production of Portland cement. (40)
7. A plant designer has to choose between equipment 1 and equipment 2, the details of which are given below:-
Equipment 1 Equipment 2
Cost Rs. 500,000 Rs. 200,000
End of the year
Maintenance cost — Rs. 10,000
Salvage value Rs.50,000 —
Service life 8 Years 4 Years
If the interest rate is 10% compounded annually, calculate the present worth of investment be made for each equipment and choose the equipment which has the lower present worth. (40)
8. (a) Describe the different meteorological variables which influence severity of pollution. Define lapse rate and temperature inversion. (20)
(b) Explain the different techniques employed to use forest biomass solid waste as domestic and industrial fuel supplement. (20)