IBX - Process Eq. and PD Sec. 1 to 8

Question 1

Fresh water carrying pipelines in chemical industries are coloured with __________ color.

sea green
brown
yellow
red

Answer 1

sea green

Question 2

Which of the following material is seldom used for pressure vessel construction?

Rimmed steel
Mild steel
Killed steel
Semi-killed steel

Answer 2

Rimmed steel

Question 3

The ratio of shear stress to shear strain is called

bulk modulus
shear modulus
modulus of rigidity
modulus of elasticity

Answer 3

shear modulus

Question 4

25 per cent cut segmental baffle means that the baffle

height is 75% of the I.D. of the shell.
height is 25% of the I.D. of the shell.
spacing is 75% of its height.
width is 25% of its height.

Answer 4

height is 75% of the I.D. of the shell.

Question 5

Liquid/petroleum fuel storage tanks are built underground (as in case of petrol pumps), when the storage capacity is less than __________ kilolitres.

20
30
45
85

Answer 5

45

Question 6

Le/D for fully open globe value may be around

10
25
75
300

Answer 6

300

Question 7

Lug support is

the most suitable for thick vertical vessel.
same as bracket support.
provided usually for vessels of much smaller height than skirt supported vessels.
all (a), (b) and (c).

Answer 7

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

Question 8

Pick out the wrong statement pertaining to the use of valve tray, seive tray and bubble cap trays in continuous distillation column.

Bubble cap trays though most expensive are the best in situations, where low vapour rates is to be handled and a positive liquid seal is essential at all flow rates.
Murphree efficiency of all the three trays are nearly equal, however the peak efficiency is generally higher for seive and valve trays than the bubble cap.
Maintenance cost for valve and seive trays are comparatively more than bubble cap tray due to their relatively complicated construction features.
Valve trays have the highest turn down ratio (i.e. the ratio of the highest to the lowest vapour flow rates) and thus provides the maximum flexible operating range.

Answer 8

Maintenance cost for valve and seive trays are comparatively more than bubble cap tray due to their relatively complicated construction features.

Question 9

With increase in the number of shell passes, the value of FT

increases
decreases
remains same
remains same, only if the number of tube passes does not change.

Answer 9

increases

Question 10

Holes of a sieve tray are arranged in triangular pitch of __________ times the hole diameter.

1.5 to 2
2.5 to 5
5 to 10
10 to 15

Answer 10

2.5 to 5

Question 11

In case of a shell and tube heat exchanger, the minimum shell thickness for carbon steel (inclusive of corrosion allowance) depends on shell diameter and is in the range of __________ mm.

3-5
5-11
8-15
12-18

Answer 11

5-11

Question 12

The stress developed in a material without any permanent set is called the

ultimate stress
yield stress
elastic limit
breaking stress

Answer 12

elastic limit

Question 13

In a shell and tube heat exchanger, the ‘tube pitch’ is defined as the

O.D. of the tube for square pitch.
shortest distance between two adj acent tube holes.
shortest centre to centre distance between adjacent tubes.
none of these.

Answer 13

shortest centre to centre distance between adjacent tubes.

Question 14

Which of the following is not a valid assumption in continuous binary distillation for calculating the number of equilibrium stages by Mc-Cabe-Thiele’s method?

Sensible heat changes for vapour & liquid are negligibly small.
Reflux is not a saturated liquid.
Molar latent heat of the two components are equal.
Heat of mixing of normal liquid is assumed to be zer

Answer 14

Reflux is not a saturated liquid.

Question 15

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)

η = 17 - 61.1 log μ
η = 24.6 Δp/μ
η = 1.66 - 0.25 log μ
η = 0.25 log μ - 1.67

Answer 15

η = 17 - 61.1 log μ

Question 16

The value of fouling factor depends upon the

characteristic of process fluid.
velocity of process fluid containing suspended solids.
suspended solids in the fluid.
all (a), (b) and (c).

Answer 16

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

Question 17

In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about __________ cms.

10
20
30
35

Answer 17

10

Question 18

Tube side pressure drop in a 1-2 heat exchanger (for turbulent flow of fluids through the tubes) is about __________ times, that in a 1-1 heat exchanger having the same size & number of tubes and operated at the same liquid flow rate.

2
1/2
4
8

Answer 18

8

Question 19

To keep the power input constant for a stirred vessel operating under fully developed turbulent flow conditions (constant power number), if the impeller diameter is increased by 20%, the impeller speed should be decreased by a factor of

(1.2)^(3/2)
(1.2)^(3/5)
(1.2)^(2/3)
(1.2)^(5/3)

Answer 19

(1.2)^(5/3)

Question 20

In a heat exchanger, shell side fluid velocity can be changed by changing the tube

layout
pitch
both (a) & (b)
neither (a) nor (b)

Answer 20

both (a) & (b)

Question 21

Where does the maximum tensile strength occur in a thick cylindrical vessel subjected to internal pressure?

At the inner surface.
At the mid thickness of the cylindrical wall.
At the outer surface.
None of these.

Answer 21

At the inner surface.

Question 22

It is not desirable to design a heat exchanger for LMTD correction factor, FT, of less than

0.99
0.95
0.80
0.55

Answer 22

0.80

Question 23

A rivetted joint does not fail by __________ of rivets.

tearing
shearing
tearing of the plate across a row
none of these

Answer 23

none of these

Question 24

Triangular pitch tube layout as compared to square pitch in a shell and tube heat exchanger

permits the use of less tubes in a given shell diameter.
facilitates comparatively easier external cleaning because of large clearance.
permits the use of more tubes in a given shell diameter.
both (b) and (c).

Answer 24

permits the use of more tubes in a given shell diameter.

Question 25

Bracket supports are the most suitable for supporting __________ vessels.

thick walled vertical
horizontal
thin shperical (e.g. Horton sphere)
none of these

Answer 25

thick walled vertical

Question 26

In a multipass shell and tube heat exchanger, the shell side cross flow area does not depend upon

baffle spacing
clearance
pitch
none of these

Answer 26

none of these

Question 27

Two iron pipes of the same nominal diameter but different schedule numbers will have the same

inside diameter
outside diameter
wall thickness
none of these

Answer 27

inside diameter

Question 28

Steam side heat transfer co-efficient for design consideration under ordinary condition can be assumed to be about __________ kcal/hr.m2.°C.

1250
2500
7500
15000

Answer 28

7500

Question 29

Pick out the wrong statement.

For all the cylindrical process vessels operating above atmospheric pressure, formed heads are used for closing the vessel.
Fouling factor of river water is less than that of sea water.
Risers provided in bubble cap trays in the distillation column facilitate the flow of both liquid and vapor.
both (b) and (c).

Answer 29

both (b) and (c).

Question 30

Lessing ring is formed by the addition of a partition across the centre of a raschig ring, which results in an area increase of about __________ percent.

5
20
35
55

Answer 30

20

Question 31

In chemical process equipments, the conical bottom heads used, usually has an apex angle of

20°
40°
60°
80°

Answer 31

60°

Question 32

Smaller sized packings are generally dumped to the packed columns, and the large ones of size greater than __________ mm are stacked individually, which provides better control over bed porosity and offers lower gas pressure drop.

25
50
75
150

Answer 32

75

Question 33

Shell side heat transfer co-efficient in case of square pitch as compared to the triangular pitch under similar condition of fluid flow and tube size is

more
same
less
twice

Answer 33

less

Question 34

Correct use of ‘factor of safety’ is very important in equipment design. It is defined as the ratio of the

ultimate stress to breaking stress.
ultimate stress to working stress.
working stress to ultimate stress.
none of these.

Answer 34

ultimate stress to working stress.

Question 35

The operating velocity in the absorption tower is usually 40-50% of the flooding velocity. Packed absorption towers are normally designed for a pressure drop of about __________ mm of water column per metre height of packing.

1-5
20-40
100-150
1000-1500

Answer 35

20-40

Question 36

__________ tray arrangement is recommended for distillation column having diameter upto 4 ft.

Radial flow
Cross flow
Split flow
Cascade

Answer 36

Cross flow

Question 37

What is the value of ‘q’ for saturated liquid feed to a distillation column?

0
<1
1
>1

Answer 37

1

Question 38

In perforated plate towers, the

hole sizes may be around 1/8” or 3/16”.
total hole area may be around 6 to 15% of tower cross-sectional area.
pressure drop is less compared is similar bubble cap towers.
all (a), (b) and (c).

Answer 38

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

Question 39

The main purpose of providing stepping on the trays is to

increase the residence time.
decrease the pressure drop.
facilitate handling of large flow rate of liquid.
improve the flow condition.

Answer 39

facilitate handling of large flow rate of liquid.

Question 40

The operating pressure drop range in a bag filter is about __________ mm water gauge.

50-150
5-10
500-1500
1500-2500

Answer 40

50-150

Question 41

The ends of a cylinderical vessel can be closed by a head, which can be one of the four shapes. For the same thickness, choose the one which can withstand the highest pressure.

Flat plate
Hemispherical
Torispherical
Ellipsoidal

Answer 41

Ellipsoidal

Question 42

For laminar flow (NRe < 2100) in steel pipe, the optimum inside pipe diameter is given by

Di, opt = 3 Q^0.36 ρ^0.18
Di, opt = 3.9 Q^0.45 . ρ^0.23
Di, opt = 7.6 Q^0.36 . ρ^0.9
Di, opt = 3 Q^0.36 . ρ1.86 μ^0.08

Answer 42

Di, opt = 3 Q^0.36 ρ^0.18

Question 43

Pick out the correct statement.

When highly corrosive fluids are to be handled, the plate towers prove to be cheaper and easier to construct than packed tower.
Packed towers are generally preferred over plate towers, if the liquids have a foaming tendency.
The pressure drop through the packed towers is generally more than the pressure drop through plate towers designed for same duty.
none of these.

Answer 43

Packed towers are generally preferred over plate towers, if the liquids have a foaming tendency.

Question 44

Wall thickness of schedule 40 pipe as compared to that of schedule 80 pipe is

more
less
same
cither (a) or (b); depends upon the I.D. of the pipe

Answer 44

less

Question 45

Pick out the wrong statement pertaining to the design of a basket type evaporator.

It is used for high viscosity liquor having large rate of scaling.
The tube bundle is suspended on bracket.
There is no central downtake.
Downtake is formed by the annular space between the bundle and the shell.

Answer 45

It is used for high viscosity liquor having large rate of scaling.

Question 46

Pick out the wrong statement pertaining to the design of the bubble cap tray of a distillation column to give stable operation and even vapour distribution.

The pressure drop due to the caps & slots and the static submergence should be as high as practicable for reasonable operation.
Tendency towards stable operation is increased by increasing the skirt clearance of the caps, lowering the rate of liquid flow per unit plate width or increasing the spacing between the caps.
The dimensionless ratio of liquid gradient to pressure drop head caused by the bubble cap assembly should be less than 0.4.
none of these.

Answer 46

none of these.

Question 47

Speed of the drum of the rotary vacuum filter normally ranges from __________ rpm.

0.1 to 2
5 to 7
3 to 8
8 to 15

Answer 47

0.1 to 2

Question 48

A stuffing box is used for

absorbing the contraction/expansion of pipeline due to temperature changes.
prevention of fluid leakage around moving parts.
facilitating smooth opening and closing of a valve.
reducing the resistance of fluid flow.

Answer 48

prevention of fluid leakage around moving parts.

Question 49

Pressure drop (Δp) and the superficial gas mass velocity (G) in case of packed absorption tower operating in the preloading range are related as

Δp = G
Δp = G^0.5
Δp = G^2
Δp = 1/G^0.6

Answer 49

Δp = G^2

Question 50

Pick out the wrong statement.
In an agitated vertical cylinderical reaction vessel, the

ratio of liquid depth to tank diameter (i.e. the filling ratio) recommended for most purposes is 1.
filling ratio for dispersing gas in a liquid is 2 for sufficiently long contact period.
flat bottom and conical bottom vessels have low agitation efficiency for agitation of heavy solids in liquids.
dished bottom vessel has very high power consumption.

Answer 50

dished bottom vessel has very high power consumption.

Question 51

Needle valves are generally not used for

very large diameter pipes.
high pressure throttling service.
very accurate flow control.
smaller sizes of pipe.

Answer 51

very large diameter pipes.

Question 52

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

flow rates of each fluid.
type and size of packing.
concentration of each fluid.
all a, b & c.

Answer 52

all a, b & c.

Question 53

Pick out the wrong statement.

Safety valves are provided in heat exchangers for removal of non-conden-sables.
Liquid metals and dowtherm are used for very high temperature heating.
In a shell and tube heat exchanger, high pressure fluid is generally routed through the tube.
A loop seal or U-seal is provided in a vertical condenser sub-cooler to prevent quick draining of the condensate.

Answer 53

Safety valves are provided in heat exchangers for removal of non-conden-sables.

Question 54

With increase in gas flow rate to fabric surface area ratio (Nm3/hr/m2 fabric surface area), the size & the cost of a bag filter

increases
decreases
remain unaffected
none of these

Answer 54

decreases

Question 55

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

central dished section and corner torus section.
corner torus section and central dished section.
central dished section and straight flange section.
straight flange section and corner torus section.

Answer 55

central dished section and corner torus section.

Question 56

Number of evaporators which can be used in service in a multiple effect evaporation system is limited by the

practical limit reached, due to low heat transfer rate because of inadequate temperature difference.
economic limit reached, when the plant cost exceeds the saving of steam.
both (a) & (b).
neither (a) nor (b).

Answer 56

both (a) & (b).

Question 57

Which of the following is used to set the diameter of the distillation column?

Number of theorectical plates.
Static submergence.
Allowable vapour velocity.
Length of straight rectangular weir on cross-flow tray.

Answer 57

Allowable vapour velocity.

Question 58

Ponchon Savarit method is based on the use of enthalpy concentration diagram, which contains the bubble point curve (saturated liquid curve), dew point curve (saturated vapour curve) and equilibrium tie lines. As compared to McCabe-Thiele’s method, this method

is more accurate in finding the number of equilibrium stages.
accounts for the enthalpy changes in the process.
facilitates direct calculation of heat load on reboiler & condenser from, the diagram used in this method.
all ‘a’, ‘b’ & ‘c’.

Answer 58

all ‘a’, ‘b’ & ‘c’.

Question 59

The optimum size ratio for two mixed reactors in series depends on the kinetics of the reaction and the conversion level. For reaction orders more than one, the

equal sized reactors are the best.
smaller reactor should come first.
larger reactor should come first.
none of these.

Answer 59

smaller reactor should come first.

Question 60

In a shell and tube heat exchanger, tube side __________ of the mass velocity.

heat transfer co-efficient is proportional to 0.8th power
pressure drop is proportional to the square
both ‘a’ & ‘b’
neither ‘a’ nor ‘b’

Answer 60

both ‘a’ & ‘b’

Question 61

Which of the following is not a graphical method (but is an analytical method) for the calculation of theoretical number of stages in case of continuous binary distillation?

Sorel-Lewis method.
McCabe-Thiele’s method.
Ponchon-Savarit method.
none of these.

Answer 61

Sorel-Lewis method.

Question 62

Saddle supports are used for supporting __________ vessels.

horizontal cylinderical
tall vertical
thick walled vertical
thick spherical

Answer 62

horizontal cylinderical

Question 63

The diameter of a propeller agitator used in agitation tank ranges from __________ percent of the tank diameter and its peripherial speed is normally 300 to 500 metres/minute.

5 to 10
15 to 30
40 to 50
55 to 75

Answer 63

15 to 30

Question 64

In packed towers provided with saddle packing, liquid redistributors are positioned at every __________ times column diameter or 6 metres whichever is less.

2-3
5-8
10-15
20-25

Answer 64

5-8

Question 65

Optimum reflux ratio in a continuous distillation column is determined by the

maximum permissible vapour velocity.
flooding limit of the column.
total cost consideration (fixed cost of the column plus the cooling water & steam cost).
none of these.

Answer 65

total cost consideration (fixed cost of the column plus the cooling water & steam cost).

Question 66

Cooling water fouling factors vary in the range of 0.001 to 0.003

(BTU/hr.ft2 . °F)-1
(kcal/hr.m2 .°C)-1
(W/m2.°K)-1
(kcal/hr. m. °C)-1

Answer 66

(BTU/hr.ft2 . °F)-1

Question 67

Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter)

0.2 D
0.5 D
0.66 D
0.80 D

Answer 67

0.2 D

Question 68

The maximum liquid gradient over a tray must not exceed

0.5” -1.25”.
2”-3.5”.
5”.
half the tray spacing.

Answer 68

0.5” -1.25”.

Question 69

An underdesigned steam trap will

waste steam.
destroy itself of acceleration wear due to rapid recycling.
back up condensate and cause water hammer in steam line.
none of these.

Answer 69

back up condensate and cause water hammer in steam line.

Question 70

The slope of the feed line in distillation opeartion is given by (where, q = fraction of the feed stream that is liquid.)

-q
-q/(1-q)
-q/(q-1)
none of these

Answer 70

-q/(1-q)

Question 71

Speed of industrial paddle agitator ranges from __________ rpm.

1 to 5
20 to 100
500 to 750
1000 to 2000

Answer 71

20 to 100

Question 72

__________ strain is measured using a ‘strain rosetter’.

Volumetric
Shear
Linear
none of these

Answer 72

Linear

Question 73

Thin spherical shells subjected to internal pressure, develop __________ stresses.

radial
circumferential
both (a) & (b)
neither (a) nor (b)

Answer 73

radial

Question 74

With increase in the reflux ratio for a fixed production from a continuous binary distillation column, the __________ decreases.

fixed charges initially
running cost of cooling water for condenser
vapour & liquid load both
running cost of steam for reboiler

Answer 74

fixed charges initially

Question 75

The slope of operating line in the rectifying section of a distillation column is unity, if the reflux ratio is

0
∞
1
minimum

Answer 75

∞

Question 76

Vertical vessels are not supported by

brackets
skirts
columns
saddles

Answer 76

saddles

Question 77

With increase in pressure drop (for a given particle size), the dust collection efficiency of a cyclone separator will

increase
decrease
remain unaffected
increase or decrease depending on the nature of the dust.

Answer 77

increase

Question 78

Spherical shaped pressure vessel is considered to be the most ideal, because it can

withstand higher pressure for a given metallic shell thickness.
be fabricated very easily.
be designed without wind load considerations.
be supported very easily.

Answer 78

withstand higher pressure for a given metallic shell thickness.

Question 79

An adequate clearance between the tray and the shell wall of a distillation column is provided to

drain the liquid from the tray when the unit is not in operation.
allow for thermal expansion and facilitate installation.
avoid back-trapping.
none of these.

Answer 79

allow for thermal expansion and facilitate installation.

Question 80

Overall tray efficiency of a distillation column is the ratio of the number of

overall gas transfer units to the number of ideal trays required.
ideal trays required to the number of real trays required.
real trays required to the number of ideal trays required.
none of these.

Answer 80

ideal trays required to the number of real trays required.

Question 81

Pick out the wrong statement about the design of a sieve plate column.

An increased weir height improves the tray efficiency at the cost of high plate pressure drop; optimum wear height being 40-90 mm for column pressure above atmospheric and 6-12 mm for vacuum columns.
For segmental downcomers, the chord length is 60-80% of the column diameter. An initial value of downcomer area of 12% is taken in the design.
Width of the calming section provided at the inlet and outlet sides of the plate is 75 mm for column diameter below 1.5 metres and 100 mm for larger diameter columns.
Minimum recommended downcomer residence time for the disengagement of entrained vapour is the same for both foaming and non-foaming liquids, which is about 20 seconds.

Answer 81

Minimum recommended downcomer residence time for the disengagement of entrained vapour is the same for both foaming and non-foaming liquids, which is about 20 seconds.

Question 82

Generally, no corrosion allowance in wall thickness of a part is required, if the thickness is more than __________ mm.

10
20
30
5

Answer 82

30

Question 83

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.

0.1 to 0.25
0.3 to 0.5
0.5 to 0.6
0.65 to 0.80

Answer 83

0.1 to 0.25

Question 84

In a __________ rivetted joint, the rivets in the various rows are opposite to each other.

zig-zag
chain
diamond
none of these

Answer 84

chain

Question 85

Pick out the wrong statement:

The tensile strength of a brittle material is less than its compressive strength.
The compressive strength of a ductile materia] is less than its tensile strength.
In a thick cylindrical shell, the hoop stress is maximum at the inner radius.
The value of crushing load is more than that of buckling load for long columns.

Answer 85

The value of crushing load is more than that of buckling load for long columns.

Question 86

Generally, elliptical dished heads

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 .
resist half the pressure rating compared to hemi spherical head provided on the cylindrical shell of the same thickness and diameter.
are approximately as strong as seamless cylindrical shell having the corresponding I.D and O.D.
all (a), (b) and (c)

Answer 86

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

Question 87

Pick out the wrong statement pertaining to the comparative evaluation of performance of the packed tower and the plate tower.

Plate tower is perferred, if interstage cooling is required to remove heats of reaction or solution.
Plate tower is preferred over packed tower, if the operation involves liquids containing dispersed solids.
The total weight of a dry plate tower is usually much more than that of a dry packed tower designed for the same duty.
In operations involving large temperature changes. (e.g. distillation), plate towers are preferred over packed towers as the packing may be crushed due to large temperature changes.

Answer 87

The total weight of a dry plate tower is usually much more than that of a dry packed tower designed for the same duty.

Question 88

The circumferential (hoop) stress in a thin walled cylinderical vessel under internal pressure is

pd/2t
pd/4t
pd/t
pd/3t

Answer 88

pd/2t

Question 89

Le/D for fully open gate valves would be

much more than that for fully open globe valves.
much less (say 2% than that for fully open globe valves).
around 7.
both (b) and (c).

Answer 89

both (b) and (c).

Question 90

LMTD correction factor is used in heat exchanger design for

double pipe heat exchanger.
multipass shell and tube heat exchanger.
fouling fluids.
counter flow of hot and cold fluids.

Answer 90

multipass shell and tube heat exchanger.

Question 91

Floating head heat exchangers are used for the

heat transfer between corrosive fluids.
cases where temperature difference between the shell and the tubes is more (>50°C).
co-current heat transfer systems.
counter-current heat transfer systems.

Answer 91

cases where temperature difference between the shell and the tubes is more (>50°C).

Question 92

The most common standard size of bubble caps used in industrial operation is

1” dia cap with 0.5” dia riser.
6” dia cap with 4” dia riser.
8” dia cap with 1” dia riser.
4” dia cap with 8” dia riser.

Answer 92

6” dia cap with 4” dia riser.

Question 93

Compensation against openings in process vessels for giving inlet and outlet connections, for providing sight glasses and manholes etc. is provided for strength and rigidity. The most efficient type of compensation is of __________ type.

nozzle or rim
flared out
fluid in
ring plate

Answer 93

nozzle or rim

Question 94

In case of a continuous distillation column, increase in reflux ratio may result in the

lower fixed charges for the column.
greater cost for the reboiler heat supply.
greater cost for the condenser coolant.
all (a), (b) and (c).

Answer 94

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

Question 95

In a distillation column, the minimum residence time for liquid in the downspout is about __________ seconds.

1
8
80
180

Answer 95

8

Question 96

Thickness of the frame of a plate and frame filter as compared to that of plates is

less
same
more
either (a) or (b)

Answer 96

more

Question 97

Which of the following factors affect the pressure drop in a co-current gas-liquid absorption packed tower?

Size, shape, orientation and surface of the packing particles.
Density and viscosity of fluids.
Fluid flow rates.
All (a), (b) and (c).

Answer 97

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

Question 98

The thickness of heat transfer plates used in the plate type heat exchanger ranges from __________ mm, pressed in a single piece provided with grooves & corrugations.

0.3 to 0.8
1.25 to 3.125
3.5 to 7.0
8-12

Answer 98

1.25 to 3.125

Question 99

Rivets are generally specified by the

head diameter
shank diameter
overall length
none of these

Answer 99

shank diameter

Question 100

Length to diameter ratio of most rotary driers is in the range of

1 to 2
4 to 10
10 to 20
20 to 30

Answer 100

4 to 10

Question 101

Tube wall thickness depends on the cor-rosiveness of the fluids and their operating pressure & temperature and is specified by Birmingham wire gauge (B.W.G)-a number which varies from 8 to 18 with the numbers 14 and 16 being more commonly used. Outside diameter of tubes varies from about 15 to 50 mm; however a tube of less than __________ mm outside diameter is generally not recommended for fouling fluids.

16
19
28
38

Answer 101

19

Question 102

Angled baffles are preferred in the agitation tank to control the swirling action; if the viscosity of the liquid to be mixed is about 200 poise. However, the baffle may be completely eliminated for mixing liquids having viscoisty above __________ poise.

300
600
1000
1500

Answer 102

600

Question 103

Ratio of tube length to shell diameter for a shell and tube heat exchanger is

8 : 1 to 12 : 1 for both liquid-liquid and gas-gas heat exchangers.
4 : 1 to 8 : 1 for liquid-liquid exchanger.
< 4 : 1 for gas-gas exchangers.
both (b) & (c).

Answer 103

both (b) & (c).

Question 104

The dust collection efficiency of a cyclone separator

decreases with increase in gas flow rate.
is inversely proportional to the mass of the dust particle.
is directly proportional to the radius of the dust particle path.
none of these.

Answer 104

none of these.

Question 105

In a shell and tube heat exchanger, the overall heat transfer co-efficient is proportional to the tube side (volumetric flow rate)0.8. This is valid, only when the ratio of the tube side film resistance to the total resistance is almost equal to

∞
1
20.8
2

Answer 105

1

Question 106

Which of the following types of reactors is the safest from operation point of view?

A vapor phase reactor.
Pot type reactor.
A liquid phase reactor.
A liquid phase catalytic reactor.

Answer 106

A vapor phase reactor.

Question 107

In a bag filter, the pressure drop increases directly as the

density of the gas, but is independent of the viscosity of the gas.
density of the gas and inversely as viscosity of the gas.
viscosity of the gas and inversely as density of the gas.
none of these.

Answer 107

density of the gas and inversely as viscosity of the gas.

Question 108

The LMTD correction factor (FT) is applied in __________ heat exchangers.

1-1 cocurrent
double pipe
all multipass
all (involving liquid/liquid heat transfer)

Answer 108

all multipass

Question 109

Movement of pipeline caused by thermal expansion is taken care by providing

expansion joint.
changes in its direction.
change in the shape of pipeline.
all (a), (b) and (c).

Answer 109

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

Question 110

For a cylindrical shell, (subject to the thickness of uppermost course being more than the minimum for diaofthe tank in question), the thickness of the courses of shell.

decreases upwards.
increases upwards.
remains same throughout.
may decrease or increase upwards depending upon whether vacuum or positive pressure would be maintained inside the shell.

Answer 110

decreases upwards.

Question 111

In the design of a paddle agitator, the ratios paddle dia/tank dia normally taken as

0.1
0.8
0.25
0.5

Answer 111

0.8

Question 112

The design stress, which is more than the damaging stress, is the least unit stress that will render a member unfit for service before the end of its normal life. The design stress factor or factor of safety indicates the margin between design stress and the __________ stress.

working
damaging
allowable
none of these

Answer 112

damaging

Question 113

Hole diameter of the seive trays in the distillation column ranges from __________ mm.

1 to 3
4 to 8
3 to 12.5
12.5 to 18.5

Answer 113

3 to 12.5

Question 114

Factor of safety (i.e., overdesign factor) in heat transfer equipments is about __________ percent more than the actual/theoretical design factor.

5-10
15-20
30-35
35-40

Answer 114

15-20

Question 115

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

d1/(d1 + d2)
d2/(d1 + d2)
(d2 + d2)/d1
(d2 + d2)/d2

Answer 115

d1/(d1 + d2)

Question 116

In actual operation of distillation column, the vapour is not distributed uniformly among the bubble caps, primarily because of the

liquid gradient on the tray.
lower skirt clearance.
lower static submergence.
small downcomer liquid seal.

Answer 116

liquid gradient on the tray.

Question 117

The minimum shell thickness for tank ≤ 15 metres diameter is limited to __________ mm, for reasons of elastic stability.

2
5
10
15

Answer 117

5

Question 118

If ‘D’ is the inside diameter of the shell of a shell and tube heat exchanger, then the baffle spacing is usually in the range of

D/2 or minimum 2” to 5D.
D/5 or minimum 2” to 5D.
D/5 or minimum 2” to D.
none of these.

Answer 118

D/5 or minimum 2” to 5D.

Question 119

Brass valves are usually made for pipe sizes __________ inches.

≤1
≤2
>2.5
>3.5

Answer 119

≤2

Question 120

At the following point for a given packing and set of fluids, the pressure drop per metre of packed height, with variation in fluid rates and operating pressure

increases
decreases
remains same
may increase or decrease depending upon the solubility of the gas in the liquid

Answer 120

remains same

Question 121

In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement

results in higher shell side pressure drop.
can accomodate less number of tubes for a given shell diameter.
facilitates easier shell side cleaning; hence is more suitable for handling high dirt factor shell side fluid.
creates relatively lower turbulence on the shell side resulting in lower shell side heat transfer co-efficient.

Answer 121

results in higher shell side pressure drop.

Question 122

Pick out the wrong statement about routing of fluids in a shell and tube heat exchanger.

The corrosive and fouling fluid should be preferably routed through the tubes.
The viscous fluid should be routed through the shell side.
Lower flow rate fluid should be routed through the shell side.
Higher pressure fluid stream should be routed through the shell side.

Answer 122

Higher pressure fluid stream should be routed through the shell side.

Question 123

The necessary wall thickness for a metallic storage vessel is a function of the

ultimate tensile strength (or yield point) of the material and operating temperature.
operating pressure and welding/joint efficiency.
diameter of the vessel.
all (a); (b) and (c).

Answer 123

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

Question 124

In a multiple effect evaporator system having ‘n’ effects, the amount of water evaporated per unit surface area in approximately equal to __________ times that in a single effect.

‘n’th
(1/n)th
0.5 nth
1.5 nth

Answer 124

(1/n)th

Question 125

Pick out the wrong statement

In a flanged and standard dished head, the crown radius is ≤ shell outside diameter.
In a flanged and shallow dished head, the crown radius is > shell outside diameter.
Flat head covers are most suitable for larger vessels operating at very high pressure.
Flanged only head is a type of flat head in which gradual change in the shape at the centre results in reduced local stresses.

Answer 125

Flat head covers are most suitable for larger vessels operating at very high pressure.

Question 126

Pick out the wrong statement pertaining to the design of a horizontal tube evaporator.

It is unsuitable for concentrating those liquids, which form a scale or deposit salt.
It is suitable for process, in which the final product is a liquor instead of solid.
Its usual dimensions are: tube dia = 2-3 cms; evaporator body dia = 1-4 metres and evaporator height = 2.5-4 metres.
Liquor flows inside the tube, while the steam is outside submerging the tube.

Answer 126

Liquor flows inside the tube, while the steam is outside submerging the tube.

Question 127

Weep holes provided in the plates of a distillation column

facilitate draining out liquid from a tray when the unit is not in operation.
are normally located near the overflow weir so that any delivery of liquid during operation follows approximately the same path as the overflow fluid.
must be large enough (usually 1/4” to 5/8” dia) to prevent plugging but should not deliver excessive amount of fluid during operation.
all (a), (b) and (c).

Answer 127

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

Question 128

Steam is preferred to be used as a heating medium in heat exchangers, because of its

low cost.
high latent heat.
non-corrosive condensate.
high film co-efficient.

Answer 128

high latent heat.

Question 129

__________ shapedroof is the most commonly used roof for cylinderical storage tanks.

Conical
Flat
Dome
Umbrella

Answer 129

Conical

Question 130

Pick out the wrong statement pertaining to ‘Horton sphere’ used for the storage of liquid ammonia.

Diameter of Horton sphere is normally 6 to 25 metres and it is supported by 6 to 12 nos. tubular or rolled section column.
Thickness of spherical shell is half that of the cylinderical vessel under same operating pressure condition. Besides, the ratio of surface area to volume is less for sphere than any other shape ; hence insulation required is less.
Horton sphere is used for the storage of gases and volatile liquid at a moderate pressure of 1 to 10 kg/cm2 .
Horton sphere is used for the storage of liquid at sub-zero temperature at very high pressure upto 200 kg/cm2.

Answer 130

Horton sphere is used for the storage of liquid at sub-zero temperature at very high pressure upto 200 kg/cm2.

Question 131

Value of Peclet number = ∞, is the representative of

laminar flow.
complete back mixing,
plug flow.
eddy diffusivity = 0.

Answer 131

plug flow.

Question 132

Le/D for a Tee (used as elbow, entering branch) would be

less than that for Tee (used as elbow, entering run).
more than that for Tee (used as elbow, entering run).
around 90.
both (b) and (c).

Answer 132

both (b) and (c).

Question 133

In most of the shell and tube heat exchangers, the tube pitch is generally __________ the tube diameter.

less than
1.25 - 1.50 times
2.5 times
one-fourth of

Answer 133

1.25 - 1.50 times

Question 134

In a distillation column, bubble caps are located on trays with a pitch of __________ times the outside diameter of the caps.

1.3 to 2
1.6 to 2
2.5
1.5 to 3

Answer 134

1.3 to 2

Question 135

1.2 to 3.8 cms is the value of the

downcomer liquid seal in case of a balanced tray design.
static submergence in case of a bubble cap tray for column operating under pressure (≥ 1 atm.).
skirt clearance for bubble caps.
all (a), (b) and (c).

Answer 135

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

Question 136

Accidents in chemical plants are mostly due to

inadequate equipment design.
faulty operating procedures.
improper layout of the equipments.
failure of equipments.

Answer 136

faulty operating procedures.

Question 137

For identical operating conditions, the pressure drop over __________ tray is the highest out of the following.

sieve
valve
counterflow
bubble cap

Answer 137

bubble cap

Question 138

A perforated plate has holes of diameter dn arranged in a pitch ph. Each hole has a tube of I.D. dt passing through it. The ligament efficiency is given by

(ph - dh)/ph
(ph - dh . dt/2)/ph
(ph - dt)/ph
(ph - dh)/dh

Answer 138

(ph - dt)/ph

Question 139

__________ is the determining factor for the number of bubble caps to be used per tray.

Permissible slot velocity
Tray diameter
Liquid load
Vapor load

Answer 139

Permissible slot velocity

Question 140

Pick out the wrong statement about distillation operation.

Distillation under vacuum is a substitute for steam distillation.
In differential (simple) distillation, the vapour is removed as soon as it is formed without appreciable condensation.
In flash (equilibrium) distillation, a definite fraction of liquid is vaporised in such a way that the evolved vapour & residual liquids are in equilibrium with each other.
Flash distillation, differential distillation & steam distillation are all continuous distillation processes.

Answer 140

Flash distillation, differential distillation & steam distillation are all continuous distillation processes.

Question 141

Low pressure steam (with saturation temperature between 105 to 120°C) is usually used in the vacuum evaporators, which normally employ a vacuum of about __________ mm Hg (referred to a 760 mm mercury barometer).

250
450
650
750

Answer 141

650

Question 142

Which of the following is the best tube material from thermal conductivity point of view alone?

Aluminium
Stainless steel
Copper
Carbon steel

Answer 142

Copper

Question 143

Normal screwed fittings are used for pipes upto a diameter of __________ inches.

1.5
3
5
7

Answer 143

3

Question 144

In a shell and tube heat exchanger, the clearance of the tube is generally

not less than one-fourth of the tube diameter or 3/16”.
more than the tube diameter.
equal to the tube diameter.
more in case of triangular pitch as compared to the square pitch tube layout.

Answer 144

not less than one-fourth of the tube diameter or 3/16”.

Question 145

Diameter of the seive tray column is determined by the

lower limit of vapour velocity.
upper limit of the vapour velocity.
hole diameter of the seive tray.
height of the plate spacing.

Answer 145

upper limit of the vapour velocity.

Question 146

For a given fluid, as the pipe diameter increases, the pumping cost

decreases.
increases.
remains unaffected.
may increase or decreaes depending upon whether the fluid is Newtonian or non-Newtonion.

Answer 146

decreases.

Question 147

Maximum acceptable total liquid gradient over a tray is about __________ mm.

5.5
12.5
30.5
45.5

Answer 147

12.5

Question 148

In case of a ‘thin’ pressure vessel, the ratio of its diameter to wall thickness is

< 10
> 10
> 20
30

Answer 148

> 10

Question 149

High pressure fluid in a shell and tube heat exchanger should preferably be routed through the

tubes to avoid the expansion of high-pressure shell construction.
shell side for smaller total pressure drop.
shell side, if the flow is counter-current and tube side if the flow is co-current.
shell side for large overall heat transfer co-efficient.

Answer 149

tubes to avoid the expansion of high pressure shell construction.

Question 150

Bubble cap tray is the most commonly used tray in large distillation column, because

of its flexibility and nearly constant efficiency under varying conditions of operation.
it incurs less pressure drop as compared to any other try designed for the same duty.
it eliminates the foaming and entrain-ment tendency during operation.
none of these.

Answer 150

of its flexibility and nearly constant efficiency under varying conditions of operation.

Question 151

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 151

Aa = Sa

Question 152

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

Answer 152

hG = 1.004G^0.37

Question 153

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 153

D^5

Question 154

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

30°
45°
60°
75°

Answer 154

60°

Question 155

Pressure drop due to pipe fittings can be estimated by the equation, ΔP/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 (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 155

45 and 75

Question 156

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

10
20
30
40

Answer 156

10

Question 157

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 157

both (a) and (b)

Question 158

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 158

G^0.8

Question 159

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

half
equal to
twice
eight times

Answer 159

twice

Question 160

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 160

electrode area.

Question 161

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 161

1 to 1.5

Question 162

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 162

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

Question 163

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 163

S1/S2

Question 164

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 164

hold baffle in space.

Question 165

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.)

(ZHρ)/L
L/(ZHρ)
(Hρ)/L
(ZH)/(Lρ)

Answer 165

(ZHρ)/L

Question 166

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 166

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

Question 167

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 167

σh = 2 σL

Question 168

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

inner
outer
approximate
none of these

Answer 168

approximate

Question 169

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 169

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

Question 170

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 170

4 to 8

Question 171

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)

(D2^2 - D1^2)/D1^2
D2 - D1
(D2^2 - D1^2)/D2^2
none of these

Answer 171

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

Question 172

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

0
∞
> 1
< 1

Answer 172

> 1

Question 173

__________ shaped roof is most commonly used for cylindrical tanks.

Cone
Dome
Umbrella
Flat

Answer 173

Cone

Question 174

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

radial
circumferential tensile
compressive
longitudinal

Answer 174

circumferential tensile

Question 175

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 175

17-34