Papers : IFS - Indian Forest Service Chemical Engineering Previous Year Paper (2003)

PAPER - I : SECTION A
1. Answer any four of the following: (10 x 4 = 40)
(a) What is an incompressible fluid? Determine an expression for pressure drop in an incompressible fluid flowing in a pipe under the condition of laminar flow.
(b) Discuss the working of a centrifugal pump along with its operational problems and remedial measures.
(c) Describe the procedure to calculate number of equilibrium stages in the fractionation of a binary system by Ponchon-Savant method.
(d) Explain LMTD correction factor. How is it calculated in the use of multipass shell and tube heat exchangers?
(e) Develop a relation between heat transfer coefficient and friction factor by using colburn analogy.

2. (a) Discuss flow pattern caused by a turbine type impeller in an agitated tank and suggest ways to prevent swirling and vortex formation. (10)
(b) Explain the principle of pilot tube and its application. Also discuss how average velocity can be calculated? (10)
(c) Discuss the construction and operation of a notary drum filter. How is rate of filtration relatedto speed of rotation? (10)
(d) What is fluid energy mill ? Explain its principle. (10)

3. (a) Explain the term critical thickness of insulation. Determine an expression for it for a spherical vessel. (10)
(b) Saturated steam of atmospheric pressure condenses on a cold tube of 25 mm diameter and 1 m long. Determine per cent change in heat transfer rate if the orientation of tube is changed from horizontal to vertical. (10)

(c) Compare forward feed double effect evaporator with backward feed double effect feed evaporator. (10)
(d) Briefly discuss the procedure to calculate radiant heat load of an oil fired furnace. (10)

4. (a) Define diffusivity term, Discuss the method of measurement of diffusivity of a binary system in a laboratory. (10)
(b) Describe the procedure to calculate minimum liquid-gas ratio for absorbers. (20)
(c) Discuss the working principle of a forced draft cooling tower. (10)
(d) What are constant rate and falling rate periods in the drying of solids? Develop an expression for time of drying of a solid under falling rate period. (10)

SECTION B
5. Answer any four of the following: (10 x 4 = 40)
(a) Explain the phenomena of reverse osmosis. Discuss the characteristics of membrane required for this process.
(b) Discuss the failure of vessels based on theory of plasticity.
(c) Name various types of heads commonly used in cylindrical vessels, alongwith their sketches and areas of application.
(d) Determine an expression for frequency response of a transportation lag. Show it graphically also.
(e) Discuss ratio control and its application in process industries. Give two examples.

6. (a) What is ultrafiltration? Discuss the dependence of membrane permeation rate on applied pressure difference, feed solute concentration and cross flow velocity for ultrafiltration. (10)

(b) Discuss low pressure distillation along with its application in industries. (10)
(c) Explain (i) membrane fouling, and (ii) membrane selectivity in separation processes using membrane. (10)
(d) Explain the working principle of dialysis. (10)

7. (a) Explain Coate’s theoretical analysis for bending stress at the head-shell junction of a vessel, (10)
(b) Discuss the design procedure of skirt supports for vertical vessels. (10)

(c) A process requires a shell to be designed to contain a working pressure of 200 MN/m2. The shell temperature is 400°C, Inside diameter and length of the shell have been estimated to be 500 mm and 4000 mm, respectively. If carbon steel having an allowable stress of 10.40 x 102 MN/m2 is used as material of construction of the shell, determine suitable]e thickness of the shell. (20)

8. (a) What are various devices which can be used for absolute pressure measurement ? Discuss any one of them which can be used with continuous recording system. (10)

(b) Discuss two important characteristics of a control valve, (10)
(c) Describe the procedure for the design of sampled data controller in a system. (10)
(d) How do you find the frequency response of a PID controller? Explain it,

PAPER - II : SECTION A
1. Answer any four of the following:
(a) The normal boiling point of benzene (C6H6) is 80.1°C and its latent heat of vaporization is 33.655 kJ/mol. Estimate the vapour pressure of benzene at 45°C. (10)

(b) Prove that two reversible, adiabatic lines cannot intersect. (10)
(c) Prove that (10)
(d) For an ideal batch reactor, derive an expression to determine the time required to achieve a desired conversion. (10)
(e) Compare the size of plug flow and mixed flow reactors for first and second order reactions. (10)

2. Ethane (C2H6) is initially mixed with oxygen to obtain a mixture of 80% ethane by volume. His mixture is burned in an engine with 200% excess air. During combustion 80% of ethane burns to CO2 10% of ethane burns to CO and 10% of ethane remains unburned. Determine the composition of the exhaust gas on dry basis.

3. (a) For a particular binary system the activity coefficients are adequately represented by ln γ = 0.5 X22 and ln γ2 = 0.5 X2
1 . The saturation pressure of the components at 800C are P1 S = 900 toor and P 2 S = 600 torr (1 torr = 1 mm Hg column). Is it possible for the system to exhibit azeotropy at 800C? If so, what is the azotropic composition? (20)

4. Consider the reaction
Equal volumetric flow rates of A and B streams are fed to the reactor and each stream has a oncentration of 20 mol/liter of reactant. or 90% conversion of A,  calculate the concentration of R in the product stream or-
(a) a plug flow reactor;
(b) a mixed flow reactor. (40)


SECTION B
5. Answer any four of the following:
(a) Name the principal varnish resins and describe, in brief, the method of production of varnish. (10)
(b) Describe the production of penicillin by fermentation. (10)
(c) Explain the terms : Deflagration and Detonation, and distinguish between them. (10)
(d) With the help of neat sketches, describe adiabatic lapse rate and its effect on different types of plume behaviour. (10)
(e) Discuss the factors which must be considered in the design of activated sludge system. (10)

6. Present a neat flow diagram and describe the method of production of sucrose from sugarcane. Discuss the major engineering problems associated with the production of sucrose from sugarcane. (40)

7. (a) A proposed manufacturing plant requires an initial fixed capital investment of Rs. 5 crores and a working capital of Rs. 1 crore. It is expected that the annual income will be Rs. 4 crores and the annual expenses including depreciation will be Rs. 1.2 crores, before taxes. A minimum annual return of 25 per cent before income taxes is required. Income tax amount to 40 per cent of all pretax profits. Determine (a) the annual per cent return on the total initial investment after income taxes, and (b) the annual per cent return on the average investment before income taxes, assuming straight line depreciation and zero salvage value. (40)

8. (a) Develop mass balance equations for the food and biomass in a typical activated sludge system. (20)
(b) Define BOD and COD, and explain the methods of controlling BOD and COD in tannery effluents. (20)