Thursday 12 February 2015

CHEMICAL ENGINEERING ,PAPER- II – 2002



Time Allowed: Three hours      Maximum marks: 200
Candidates should attempt questions 1 and 5 which are compulsory, and any THREE of the remaining questions, selecting at least ONE question from each section. Assume suitable data if considered necessary, and indicate the same clearly.

SECTION A

1.     Answer any four of the following:
         (A) what is proximate analysis of coal? How do you classify Coals? Give examples.
         (B) Discuss the second law of Thermodynamics and its applications.
        (C) What are the ideal reactors? Emphasize the basic assumptions. Write the performance equations for each of these reactors (no need for derivation).
        (D)Discuss the concepts of Effective Diffusivity, Effective thermal conductivity and Effectiveness actor.
        (E)   Discuss the concepts of fugacity, activity and chemical potential.

2.     A natural gas having a composition of CH₄:80% (byvol), C₂ H₆: 8.0, C₃ H₈: 4.5, C₄H₁₀: 2.0,   C₅ H₁₂: 1.0, CO₂: 2.5 and N₂: 2.0 are burnt with excess air in a burner. The burner gases contain (on dry – basis) CO₂: 10.3, N₂: 85.9 and O₂: 3.8. Calculate the per cent excess air supplied and also the composition of the burner gases on wet basis.

3.     Calculate the equilibrium constant for the vapour –phase dehydration of ethylene at 350⁰C. The reaction :
C₂H₅ OH (g) →C₂ H₄ (g) + H₂ O (g).
Data:
Values of the constants in the heat capacity equation:
Cᵨ / R = A + BT+CT² + DT¯² (Tin deg.K)

Component         A          10³B            10⁶C           10¯⁵D
C₂H₅ OH (g)       3.518     20.001       -6.002        0.000
C₂ H₄ (g)            1.424     14.394        -4.392        0.000
H₂ O (g)              3.47        1.450          0.000         0.121
Component      ∆H ⁰ ∫ (298)        J/ mol        ∆G⁰ ∫ (298)        J/ mol
C₂H₅OH                 -235,100                               -168,490
C₂H₄                       +52,510                                   68,460
H₂O                         -241,818                              -228,572

4.     What is the importance of pore –diffusion in gas-solid) porous catalyst) reactions? Derive an expression for the effectiveness factor I order kinetics and single cylindrical pore.


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