Chemical Engineering Questions on Plant Design - Set 17 - ObjectiveBooks

Chemical Engineering Questions on Plant Design - Set 17

Practice Test: Question Set - 17

1. Pressure drop due to pipe fittings can be estimated by the equation,

P/ρ = 4f, (Le/D) (V2/2gc) 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

2. The thickness of segmental baffles (25 -35% cut truncated plates usually) is generally _________ the tube wall thickness.
    (A) Equal to
    (B) Twice
    (C) Four times
    (D) Half

3. In a distillation column, the minimum residence time for liquid in the downspout is about _________ seconds.
    (A) 1
    (B) 8
    (C) 80
    (D) 180

4. In a double pipe concentric heat exchanger, the equivalent diameter of annulus for heat transfer would be (where, D1 and D2 are I.D. of inner and outer pipes)
    (A) (D22 - D12)/D12
    (B) D2 - D1
    (C) (D22 - D12)/D22
    (D) None of these

5. In a multipass shell and tube heat exchanger, the baffles on shell side is primarily provided for
    (A) Reducing scale deposition
    (B) Increasing pressure drop
    (C) Fixing the tubes
    (D) Creating turbulence

6. A head comprises of straight flange section, corner torus, section and central dished section. Crown radius and knuckle radius in a head is related respectively to the
    (A) Central dished section and corner torus section
    (B) Corner torus section and central dished section
    (C) Central dished section and straight flange section
    (D) Straight flange section and corner torus section

7. _________ dished head is the strongest of all.
    (A) Hemispherical
    (B) Elliptical
    (C) Torispherical
    (D) None of these

8. _________ of water makes it a widely used coolant in heat exchangers.
    (A) Low corrosiveness
    (B) Low dirt factor
    (C) High specific heat
    (D) Low viscosity

9. Speed of industrial paddle agitator ranges from _________ rpm.
    (A) 1 to 5
    (B) 20 to 100
    (C) 500 to 750
    (D) 1000 to 2000

10. Hold up of material in a operating rotary drier is in the range of
    (A) 0.05 to 0.15
    (B) 0.25 to 0.50
    (C) 0.5 to 0.8
    (D) 0.8 to 0.9

11. In a shell and tube heat exchanger having triangular pitch, the shell side equivalent diameter is given by
    (A) 4(0.86P2 - πd2/4)/πd
    (B) (P2 - πd2/4)/πd
    (C) 4(0.86P2 - πd2)/πd
    (D) (4P2 + πd2/4)/πd

12. Generally, elliptical dished heads
    (A) Are manufactured on 2:1 ratio of major to minor axis and is recommended to be used for pressure vessels operating above a pressure of 1.5 MN/m2
    (B) Resist half the pressure rating compared to hemi spherical head provided on the cylindrical shell of the same thickness and diameter
    (C) Are approximately as strong as seamless cylindrical shell having the corresponding I.D and O.D
    (D) All (a), (b) and (c)

13. A pressure vessel is said to be made of 'thick' shell, if the ratio of its diameter to wall thickness is
    (A) < 10
    (B) > 10
    (C) > 20
    (D) < 20

14. For given number of passes, pitch & tube diameter, the maximum number of tubes that can be accommodated in a shell of tripled inside diameter will be _________ times.
    (A) About 9
    (B) Considerably more than 9
    (C) Considerably less than 9
    (D) About 3

15. In case of a continuous distillation column, increase in reflux ratio may result in the
    (A) Lower fixed charges for the column
    (B) Greater cost for the reboiler heat supply
    (C) Greater cost for the condenser coolant
    (D) All (a), (b) and (c)

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