Practice Test: Question Set - 13
1. Commercial packed scrubbers are normally designed for a pressure drop range of _________ mm water column per meter of packed height.
- (A) 4-8
- (B) 17-34
- (C) 52-68
- (D) 88-105
2. The distance between the top of the slots and the liquid surface when the static liquid is just ready to flow over the overflow weir is called
- (A) Downcomer liquid seal
- (B) Static submergence
- (C) Skirt clearance
- (D) None of these
3. The slope of operating line in the rectifying section of a distillation column is unity, if the reflux ratio is
- (A) 0
- (B) ∞
- (C) 1
- (D) Minimum
4. With increase in temperature drop (in a shell and tube heat exchanger), the LMTD correction factor, FT
- (A) Decreases very rapidly
- (B) Increases very rapidly
- (C) Remains constant
- (D) Increases linearly
5. Overall mass transfer co-efficient in case of absorption of _________ in water is based on the gas film co-efficient only, as the mass transfer process is gas film (phase) controlling.
- (A) CO2
- (B) SO2
- (C) NH3
- (D) None of these
6. Multiple blade paddle agitator is used for mixing high viscosity liquids/paste in which the paddle diameter is commonly 0.8 times the tank diameter. However, the width of the blade is in the range of _________ times the paddle diameter.
- (A) 0.1 to 0.25
- (B) 0.3 to 0.5
- (C) 0.5 to 0.6
- (D) 0.65 to 0.80
7. Minimum baffle spacing recommended in a shell and tube heat exchanger is equal to
- (A) 5 cms
- (B) 40% of the I.D. of the shell
- (C) 25 cms
- (D) I.D. of the shell
8. Bubble cap plate column is
- (A) A finite stage contactor
- (B) Used only for distillation, not for absorption
- (C) A differential stage contactor
- (D) A continuous contactor
9. The most common standard size of bubble caps used in industrial operation is
- (A) 1" dia cap with 0.5" dia riser
- (B) 6" dia cap with 4" dia riser
- (C) 8" dia cap with 1" dia riser
- (D) 4" dia cap with 8" dia riser
10. Shortest distance between two tubes is
- (A) Called tube pitch
- (B) Called tube clearance
- (C) More in case of triangular pitch as compared to square pitch of tube
layout
- (D) None of these
11. Pick out the wrong statement.
- (A) Plate efficiency increases with increase in superficial vapor
velocity till entrainment limit
- (B) Increase in depth of the liquid about the slots increases the plate
efficiency, particularly if the liquid depth is < 1"
- (C) Too small a plate spacing can cause a low
efficiency, if the vapor velocity is greater than the allowable value
- (D) None of these
12. Rivets are generally specified by the
- (A) Head diameter
- (B) Shank diameter
- (C) Overall length
- (D) None of these
13. Heat transfer co-efficient, hG(Kcal/hr.m2 .°C) and mass velocity of air, G (kg/hr.m2 ) for air flow parallel to the surface in case of constant drying rate in batch drying is related as hG = 0.0176G0.8. But when the flow of air perpendicular to the surface is encountered, this equation changes to
- (A) hG = 1.004G0.37
- (B) 1.004G0.8
- (C) hG = 0.0176G0.37
- (D) 0.0176G1.37
14. If a single tube pass heat exchanger is converted to two passes; for the same flow rate, the pressure drop per unit length in tube side will _________ times.
- (A) Increase by 1.8
- (B) Decrease by 22
- (C) Increase by 21.6
- (D) None of these
15. Height equivalent to a theoretical plate (HETP) is the height of packing that will give the same separation as one theoretical plate in gas-liquid mass transfer operations like distillation, absorption/stripping and humidification/dehumidification. HETP which is experimentally determined, depends upon the
- (A) Flow rates of each fluid
- (B) Type and size of packing
- (C) Concentration of each fluid
- (D) All a, b & c
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