1.  Overall distillation column efficiency for most of the refinery columns can be given by (for μ = 0.07  1.4 cp and relative volatility < 4) (where η = overall column efficiency, % μ = molal average viscosity of feed at average column temperature and pressure, cp Δp = pressure drop per tray, psi) 
a.  A 
b.  B 
c.  C 
d.  D 
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Answer: (a).A

2.  For laminar flow (Nʀₑ < 2100) in steel pipe, the optimum inside pipe diameter is given by 
a.  A 
b.  B 
c.  C 
d.  D 
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Answer: (a).A

3.  For annular flow of a fluid, the ratio of the equivalent diameter for pressure drop calculation to the equivalent diameter for heat transfer calculation is 
a.  A 
b.  B 
c.  C 
d.  D 
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Answer: (a).A

4.  Pressure drop due to pipe fittings can be estimated by the following equation, where, Lₑ = equivalent length of straight pipeline which will incur the same frictional loss as the fitting and D = diameter of the fitting. The value of Lₑ/D (dimensionless) for 45° elbow and 180° close return bends would be respectively around 
a.  5 and 10 
b.  45 and 75 
c.  180 and 300 
d.  300 and 500 
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Answer: (b).45 and 75

5.  In a rotary drier, the average retention time of solid is (where Z = length of the drier, metres ρ = apparent solid density, kg/m³ L = flow rate of dry solids, kg/see. m² drier crosssection H = hold up of solid.) 
a.  A 
b.  B 
c.  C 
d.  D 
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Answer: (a).A
