Section 4

Question 1

In common bubble cap distillation column design practice, riser area is approximately equal to (where, Aa = Annular passage area, and Sa = Slot area)

Aa = Sa
1.2 Aa = 1.2 Sa
Sa = 1.5 Aa
Aa = 1.5 Sa

Answer 1

Aa = Sa

Question 2

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

hG = 1.004 G^0.37
1.004 G^0.8
hG = 0.0176 G^0.37
0.0176 G^1.37

Answer 2

hG = 1.004 G^0.37

Question 3

In the agitators, the power required will be changed with the increase of diameter of agitator (D) as

D^2
D^5
D
D^9

Answer 3

D^5

Question 4

Apex angle of conical heads used in the bottom heads of chemical process equipments is usually

30°
45°
60°
75

Answer 4

60°

Question 5

Pressure drop due to pipe fittings can be estimated by the 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 (dimensionless) for 45° elbow and 180° close return bends would be respectively around

5 and 10
45 and 75
180 and 300
300 and 500

Answer 5

45 and 75

Question 6

A pressure vessel is said to be made of ‘thick’ shell, if the ratio of its diameter to wall thickness is

10
10
20
20

Answer 6

10

Question 7

Rate of filtrate delivery is inversely proportional to the

filtering area & the pressure difference driving force.
viscosity of filtrate.
cake & filter medium resistance.
both (a) and (b)

Answer 7

both (a) and (b)

Question 8

Tube side heat transfer co-efficient for turbulent flow of liquid through tubes is proportional to

G^0.2
G^0.5
G^0.8
G^1.5

Answer 8

G^0.8

Question 9

Circumferential (hoop) stress in a thin cylindrical vessel under internal pressure is __________ the longitudinal stress.

half
equal to
twice
eight times

Answer 9

twice

Question 10

The dust collection efficiency of electrostatic precipitator increases with increase in the

gas flow rate.
electrode area.
both (a) & (b).
neither (a) nor (b).

Answer 10

electrode area.

Question 11

For storing hazardous chemicals in large storage tanks, the minimum safe distance between the two tanks should range between __________ times the tank diameter.

1 to 1.5
2.5 to 3.5
4 to 5
6 to 8

Answer 11

1 to 1.5

Question 12

Which of the following factors determine the amount of entrainment in a distillation column ?

Plate spacing.
Depth of liquid above the bubble cap slots.
Vapour velocity in the volume between the plates.
All (a), (b) and (c).

Answer 12

All (a), (b) and (c).

Question 13

The absorption factor is defined as (where, S1 = slope of the equilibrium curve, S2 = slope of the operating line)

S1/S2
S1.S2
S2/S1
1/S1.S2

Answer 13

S1/S2

Question 14

In shell and tube heat exchangers, straight tie rods are used to

hold baffle in space.
fix the tubes in position.
account for thermal strain.
none of these.

Answer 14

hold baffle in space.

Question 15

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 cross-section H = hold up of solid.)

Answer 15

(Z H ρ ) / L

Question 16

In case of design of a shell and tube heat exchanger,

minimum cleaning lane of 6.5 mm is provided, when tubes are on a square pitch.

minimum tube sheet thickness (in which tubes are fixed) is equal to the O.D. of the tube upto 15 mm tube diameter; and for > 15 mm tube diameter, tube sheet thickness is smaller than tube diameter.

O.D. of the tube is 6 to 40 mm while the tube lengths used are 0.5, 2.5, 3.0, 4.0, 5.0, 6 metres.

all (a), (b) & (c).

Answer 16

all (a), (b) & (c).

Question 17

In a cylinderical vessel subjected to internal pressure, the longitudinal stress σL and the circumferential stress, σn are related by

σh = 2 σL

σh = σL

σh = σL/2

no relation exists

Answer 17

σh = 2 σL

Question 18

Nominal size of a pipe is an indication of its __________ diameter.

inner
outer
approximate
none of these

Answer 18

approximate

Question 19

Excessive liquid gradient on a tray may result in the

maldistribution of gas.
back trapping.
gas blowing beneath cap skit.
all (a), (b) and (c).

Answer 19

all (a), (b) and (c).

Question 20

The ratio of tube length to shell diameter in case of liquid shell and tube heat exchanger ranges from

2 to 3
3 to 5
4 to 8
6 to 12

Answer 20

4 to 8

Question 21

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)

Answer 21

(D2)^2 - (D1)^2 / (D1)^2

Question 22

What is the slope of the operating line in the stripping section of a distillation column ?

0
∞
> 1
< 1

Answer 22

> 1

Question 23

__________ shaped roof is most commonly used for cylindrical tanks.

Cone
Dome
Umbrella
Flat

Answer 23

Cone

Question 24

In a thin cylindrical shell, the hoop stress is __________ stress.

radial
circumferential tensile
compressive
longitudinal

Answer 24

circumferential tensile

Question 25

Commercial packed scrubbers are normally designed for a pressure drop range of __________ mm water coloumn per metre of packed height.

4-8
17-34
52-68
88-105

Answer 25

17-34

Question 26

The retention time of material in a rotary dryer depends upon its

rpm
slope & length
flights arrangement
all (a), (b) and (c)

Answer 26

all (a), (b) and (c)

Question 27

In actual operation of a bubble cap distillation tower, the __________ at the bottom of the tower is more than that at the top of the tower.

molal flow rate of vapour
vapour molecular weight
pressure and temperature
all (a), (b) and (c)

Answer 27

all (a), (b) and (c)

Question 28

Rotary driers are most economically designed for the number of heat transfer units (HTU) from

0.01 to 1
1.5 to 2.5
5 to 10
10 to 20

Answer 28

1.5 to 2.5

Question 29

The difficulty of liquid distribution in packed towers is accentuated, when the ratio of tower diameter to packing diameter is

< 30
< 7
> 7 < 15
> 20 < 50

Answer 29

< 7

Question 30

A forced circulation long tube vertical evaporator as compared to the natural circulation evaporator

is economical in operation.

employs high velocity, high heat transfer rate and less heating surface requirement.

employs a centrifugal pump placed between external downtake from vapor drum and inlet to tube bundle.

both (b) & (c).

Answer 30

both (b) & (c).

Question 31

An increase in the liquid resistance to interphase mass transfer and a resultant reduction in plate efficiency is caused by

an increase in liquid viscosity.

an increase in relatived volatility for rectification columns.

decrease in gas solubility for absorbers.

all (a), (b) and (c).

Answer 31

all (a), (b) and (c).

Question 32

In the design of a bag filter, the gas temperature is an important consideration, as it affects the

gas density
gas viscosity
fibre selection
all (a), (b) & (c)

Answer 32

all (a), (b) & (c)

Question 33

With increase in temperature drop (in a shell and tube heat exchanger), the LMTD correction factor, FT

decreases very rapidly
increases very rapidly
remains constant
increases linearly

Answer 33

decreases very rapidly

Question 34

The normal range of velocity of steam in pipes is __________ m/sec.

0.1-0.5
1-5
10-20
80-100

Answer 34

80-100

Question 35

__________ dished head is the strongest of all.

Hemispherical
Elliptical
Torispherical
none of these

Answer 35

Hemispherical

Question 36

Pick out the correct statement.

It is preferred to use a vertical condenser for condensation of vapor from a distillation column without sub-cooling

Draining of residual liquid on tray during shut down of distillation column is facilitated by weep holes.

Random packing a packed tower offers the advantage of lower pressure drop and higher throughput of fluids as compared to regular/stacked packing.

Risers are generally not connected to the plate in a distillation coloumn by bolts, rivets or welding.

Answer 36

Risers are generally not connected to the plate in a distillation coloumn by bolts, rivets or welding.

Question 37

“A claming section” before the liquid flows into the downcomer is privided to

permit release of entrained vapour in the liquid.
reduce the discharge fluctuation.
ensure better vapour-liquid contact.
cool the liquid before it flows down.

Answer 37

permit release of entrained vapour in the liquid.

Question 38

The units of Young’s modulus of elasticity and __________ are the same.

strain
stress
modular ratio
none of these

Answer 38

stress

Question 39

In the design of a shell and tube heat exchanger, the corrosion allowance

need not be provided for non-pressure parts like tie rods, spacers, baffles, supports etc.

for carbon steel and cast iron pressure parts is 1.5 mm (except for tubes) and for severe conditions it is 3 mm.

for internal cover and tube sheet is provided on both the sides.

all (a), (b) & (c).

Answer 39

all (a), (b) & (c).

Question 40

Vertical condenser is advantageous to the horizontal condenser from operation point of view, when

hydrostatic head is required for refluxing the condensate.

only the function of condensation is to be carried out.

sub cooling of condensate is desired.

both the functions of condensation & sub cooling are carried out in a single unit.

Answer 40

both the functions of condensation & sub cooling are carried out in a single unit.

Question 41

Hazards associated with the relief valve leakage for extremely hazardous material storage can be taken care of by providing

rupture diaphragm
dikes
surge chamber
none of these

Answer 41

rupture diaphragm

Question 42

Minimum baffle spacing recommended in a shell and tube heat exchanger is equal to

5 cms
40% of the I.D. of the shell
25 cms
I.D. of the shell

Answer 42

5 cms

Question 43

__________ liquor is best handled in a long tube vertical evaporator.

Foamy
Scaling
Viscous
Salting

Answer 43

Foamy

Question 44

Theoretically calculated diameter of the stripping section of the continuous rectification column is __________ that of the enriching section.

less than
more than
same as
either more or less (depending upon relative volatility)

Answer 44

more than

Question 45

Hold up of material in a operating rotary drier is in the range of

0.05 to 0.15
0.25 to 0.50
0.5 to 0.8
0.8 to 0.9

Answer 45

0.05 to 0.15

Question 46

A binary liquid azeotropic mixture has boiling point higher than either of the components, when it shows __________ deviation from Raoult’s Law.

positive
negative
no
none of these

Answer 46

negative

Question 47

The testing pressure of storage tanks and pressure vessels designed as per Indian standard codes should be about __________ times.the design pressure.

1.5 to 2
3 to 4
4 to 5
>5

Answer 47

1.5 to 2

Question 48

Flanges are connected to pipes by

screwing
welding
brazing
all (a), (b) and (c)

Answer 48

all (a), (b) and (c)

Question 49

The ratio of down take area to cross-sectional area of the tube, for calendria type evaporator ranges from

0.5 to 1
1 to 1.5
1.5 to 2
2 to 2.5

Answer 49

0.5 to 1

Question 50

Shortest distance between two tubes is

called tube pitch.
called tube clearance.
more in case of triangular pitch as compared to square pitch of tube layout.
none of these.

Answer 50

called tube clearance.