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indiabix > Design > Flashcards

Design Flashcards

1
Q

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

A

sea green

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2
Q

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

A

Rimmed steel

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3
Q

The ratio of shear stress to shear strain is called

A

shear modulus

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4
Q

25 per cent cut segmental baffle means that the baffle

A

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

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5
Q

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

A

45

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6
Q

L/D for fully open globe value may be around

A

300

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7
Q

Lug support is

A

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

the most suitable for thick vertical vessel.
same as bracket support.
provided usually for vessels of much smaller height than skirt supported vessels.

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8
Q

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

A

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

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9
Q

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

A

increases

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10
Q

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

A

2.5 to 5

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11
Q

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.

A

5-11

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12
Q

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

A

elastic limit

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13
Q

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

A

shortest centre to centre distance between adjacent tubes.

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14
Q

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 ?

A

Reflux is not a saturated liquid.

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15
Q

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

η = 17 - 61.1 log μ

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16
Q

The value of fouling factor depends upon the

A

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

characteristic of process fluid.
velocity of process fluid containing suspended solids.
suspended solids in the fluid.

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17
Q

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

A

10

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18
Q

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.

A

8

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19
Q

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

A

(1.2)^5/3

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20
Q

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

A

both (a) & (b)

layout
pitch

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21
Q

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

A

At the inner surface.

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22
Q

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

A

0.80

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23
Q

A rivetted joint does not fail by __________ of rivets.

A

none of these

tearing
shearing
tearing of the plate across a row

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24
Q

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

A

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

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25
Q

Bracket supports are the most suitable for supporting __________ vessels.

A

thick walled vertical

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26
Q

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

A

none of these

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27
Q

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

A

inside diameter

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28
Q

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).

A

both (b) and (c).

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29
Q

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

A

7500

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30
Q

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.

A

20

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31
Q

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

A

60°

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32
Q

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.

A

75

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33
Q

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

A

less

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34
Q

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

A

ultimate stress to working stress.

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35
Q

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.

A

20-40

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36
Q

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

A

Cross flow

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37
Q

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

A

1

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38
Q

In perforated plate towers, the

A

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

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.

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39
Q

The main purpose of providing stepping on the trays is to

A

facilitate handling of large flow rate of liquid.

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40
Q

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

A

50-150

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41
Q

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.

A

Ellipsoidal

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42
Q

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

A

Di, opt = 3 Q^0.36 ρ^0.18

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43
Q

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.

A

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

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44
Q

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

A

less

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45
Q

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

A

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

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46
Q

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.

A

none of these.

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47
Q

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

A

0.1 to 2

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48
Q

A stuffing box is used for

A

prevention of fluid leakage around moving parts.

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49
Q

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

A

Δp = G2

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50
Q

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

A

dished bottom vessel has very high power consumption.

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51
Q

Needle valves are generally not used for

A

very large diameter pipes.

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52
Q

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

all a, b & c.

flow rates of each fluid.
type and size of packing.
concentration of each fluid.

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53
Q

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.

A

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

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54
Q

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

A

decreases

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55
Q

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.

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56
Q

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

A

both (a) & (b).

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.

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57
Q

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

A

Allowable vapour velocity.

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58
Q

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

A

all ‘a’, ‘b’ & ‘c’.

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.

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59
Q

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

A

smaller reactor should come first.

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60
Q

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

A

both ‘a’ & ‘b’

heat transfer co-efficient is proportional to 0.8th power
pressure drop is proportional to the square

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61
Q

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?

A

Sorel-Lewis method.

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62
Q

Saddle supports are used for supporting __________ vessels.

A

horizontal cylinderical

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63
Q

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.

A

15 to 30

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64
Q

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

A

5-8

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65
Q

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

A

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

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66
Q

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

A

(BTU/hr.ft2 . °F)-1

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67
Q

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

A

0.2 D

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68
Q

The maximum liquid gradient over a tray must not exceed

A

0.5” -1.25”.

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69
Q

An underdesigned steam trap will

A

back up condensate and cause water hammer in steam line.

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70
Q

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

A

-q/(1-q)

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71
Q

Speed of industrial paddle agitator ranges from __________ rpm.

A

20 to 100

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72
Q

__________ strain is measured using a ‘strain rosetter’.

A

Linear

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73
Q

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

A

radial

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74
Q

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

A

fixed charges initially

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75
Q

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

A

∞

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76
Q

Vertical vessels are not supported by

A

saddles

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77
Q

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

A

increase

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78
Q

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

A

withstand higher pressure for a given metallic shell thickness.
be fabricated very easily.

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79
Q

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

A

allow for thermal expansion and facilitate installation.

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80
Q

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

A

ideal trays required to the number of real trays required.

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81
Q

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.

A

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.

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82
Q

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

A

30

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83
Q

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

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84
Q

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

A

chain

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85
Q

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 colmns.

A

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

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86
Q

Generally, elliptical dished heads

A

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

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87
Q

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

A

pd/2t

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88
Q

L/D for fully open gate valves would be

A

both (b) and (c).

much less (say 2% than that for fully open globe valves).
around 7.

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89
Q

LMTD correction factor is used in heat exchanger design for

A

multipass shell and tube heat exchanger.

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90
Q

Floating head heat exchangers are used for the

A

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

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91
Q

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

A

6” dia cap with 4” dia riser.

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92
Q

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.

A

nozzle or rim

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93
Q

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

A

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

lower fixed charges for the column.
greater cost for the reboiler heat supply.
greater cost for the condenser coolant.

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94
Q

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

A

8

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95
Q

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

A

more

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96
Q

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

A

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

Size, shape, orientation and surface of the packing particles.
Density and viscosity of fluids.
Fluid flow rates.

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97
Q

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.

A

1.25 to 3.125

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98
Q

Rivets are generally specified by the

A

shank diameter

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99
Q

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

A

4 to 10

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100
Q

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.

A

19

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101
Q

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.

A

600

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102
Q

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

A

both(b) & (c).

4 : 1 to 8 : 1 for liquid-liquid exchanger.
< 4 : 1 for gas-gas exchangers.

103
Q

The dust collection efficiency of a cyclone separator

A

none of these.

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.

104
Q

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

A

1

105
Q

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

A

A vapor phase reactor.

106
Q

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

A

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

107
Q

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

A

all multipass

108
Q

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

A

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

expansion joint.
changes in its direction.
change in the shape of pipeline.

109
Q

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

A

decreases upwards.

110
Q

In the design of a paddle agitator, the ratiois normally taken as

A

0.8

111
Q

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.

A

damaging

112
Q

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

A

3 to 12.5

113
Q

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

A

15-20

114
Q

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

d1/d1+d2

115
Q

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

A

liquid gradient on the tray.

116
Q

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

A

5

117
Q

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

A

D/5 or minimum 2” to 5D.

118
Q

Brass valves are usually made for pipe sizes __________ inches.

A

≤2

119
Q

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

A

remains same

120
Q

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

A

results in higher shell side pressure drop.

121
Q

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

A

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

122
Q

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

A

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

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

123
Q

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.

A

(1/n)th

124
Q

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.

A

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

125
Q

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.

A

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

126
Q

Weep holes provided in the plates of a distillation column

A

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

127
Q

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

A

high latent heat.

128
Q

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

A

Conical

129
Q

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

A

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

130
Q

Value of Peclet number = ∞, is the representative of

A

plug flow.

131
Q

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

A

both b and c

more than that for Tee (used as elbow, entering run).
around 90.

132
Q

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

A

1.25-1.50 times

133
Q

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

A

1.3 to 2

134
Q

1.2 to 3.8 cms is the value of the

A

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

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.

135
Q

Accidents in chemical plants are mostly due to

A

faulty operating procedures.

136
Q

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

A

bubble cap

137
Q

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

A

(ph - dt)/ph

138
Q

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

A

Permissible slot velocity

139
Q

Pick out the wrong statement about distillation operation

A

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

140
Q

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).

A

650

141
Q

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

A

Copper

142
Q

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

A

3

143
Q

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

A

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

144
Q

Diameter of the seive tray column is determined by the

A

upper limit of the vapour velocity.

145
Q

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

A

decreases.

146
Q

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

A

12.5

147
Q

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

A

> 10

148
Q

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

A

tubes to avoid the expansion of high pressure shell construction.

149
Q

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

A

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

150
Q

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

A

Aa = Sa

151
Q

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

152
Q

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

A

D5

153
Q

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

A

60°

154
Q

The value of (dimensionless) L/Dfor 45° elbow and 180° close return bends would be respectively around

A

45 and 75

155
Q

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

A

10

156
Q

Rate of filtrate delivery is inversely proportional to the

A

both (a) and (b)

filtering area & the pressure difference driving force.
viscosity of filtrate.

157
Q

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

A

G^0.8

158
Q

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

A

twice

159
Q

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

A

electrode area.

160
Q

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

A

1 to 1.5

161
Q

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

A

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

Plate spacing.
Depth of liquid above the bubble cap slots.
Vapour velocity in the volume between the plates.

162
Q

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

A

S1/S2

163
Q

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

A

hold baffle in space.

164
Q

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.)

A

ZHp/L

165
Q

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

A

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

166
Q

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

A

σh = 2 σL

167
Q
A
167
Q

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

A

approximate

168
Q

Excessive liquid gradient on a tray may result in the

A

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

169
Q

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

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

170
Q

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

A

> 1

171
Q

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

A

circumferential tensile

172
Q

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

A

17-34

173
Q

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

A

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

174
Q

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.

A

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

175
Q

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

A

1.5 to 2.5

176
Q

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

A

< 7

177
Q

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

A

both (b) & (c).

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.

178
Q

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

A

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

179
Q

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

A

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

180
Q

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

A

decreases very rapidly

181
Q

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

A

80-100

182
Q

__________ dished head is the strongest of all.

A

Hemispherical

183
Q

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.

A

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

184
Q

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

A

permit release of entrained vapour in the liquid.

185
Q

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

A

stress

186
Q

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

A

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

187
Q

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

A

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

188
Q

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

A

rupture diaphragm

189
Q

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

A

5 cms

190
Q

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

A

Foamy

191
Q

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

A

more than

192
Q

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

A

0.05 to 0.15

193
Q

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

A

negative

194
Q

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

A

1.5 to 2

195
Q

Flanges are connected to pipes by

A

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

196
Q

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

A

0.5 to 1

197
Q

__________ tower is the most suitable gas-liquid contacting device involving highly corrosive fluids.

A

Packed

198
Q

At equal mass velocities, the values of film co-efficients for gases as compared to that for liquids are generally.

A

lower

199
Q

The ratio of the largest load in a test to the original cross-sectional area of the test specimen is called the __________ stress.

A

ultimate

200
Q

Baffle spacing is generally __________ the I.D. of the shell.

A

both (b) and (c)

not greater than
not less than one fifth of

201
Q

The wall thickness of thin cylindrical shell with hemispherical ends is __________ that of the spherical ends.

A

more than

202
Q

A ‘rupture disc’ is provided in chemical equipments as an accessory meant for

A

relieving excess pressure.

203
Q

In a vertical short tube evaporator (Calendria type), the

A

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

204
Q

In a multipass shell and tube heat exchanger, the problem of differential expansion between the shell and tube passes is taken care of by using a

A

either (a) or (b)

U-bend
floating head tube sheet

205
Q

In a shell and tube heat exchanger, the shortest centre to centre distance between the adjacent tubes is

A

called tube pitch.

206
Q

Any shell opening greater than 5 cms for a storage tank must be reinforced for reason of

A

preventing the local overstressing of the shell around the opening.

207
Q

Minimum tube pitch recommended for shell and tube heat exchangers is about __________ times the outside diameter of the tube.

A

1.25

208
Q

Liquid redistribution should be done in a packed tower packed with raschig rings every 6 metres or __________ times the column diameter, whichever is lower.

A

2.5-3.0

209
Q

Slope of countercurrent flow rotary drier is in the range of __________ meter/metre.

A

0 to 0.08

210
Q

In case of saddle packing (e.g., berl and intralox saddles), the maximum size of the packing should not exceed __________ of the column diameter.

A

l/15th

211
Q

Seamless pipe is made

A

both (b) and (c).

212
Q

The thermal stress in a metallic bar does not depend upon the

A

cross-sectional area.

213
Q

The minimum baffle height should be

A

twice the impeller diameter.

214
Q

For turbulent flow (NRe > 2100) of low viscosity fluid (μ > 20cp) in steel pipes, the optimum inside pipe diameter is given by(where, Q = fluid flow rate, ft3/sec.ρ = fluid density, lb/ft3 μ = fluid viscosity, centipoise Di = optimum inside pipe diameter, inches)

A

Di, opt = 3.9 Q0.45 ρ0.13

215
Q

To avoid the tearing off the plate of an edge, the margin (i.e., the minimum distance from the centre of the rivet hole to the nearest edge of the plate) should be equal to

A

1.5 d

216
Q

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

A

1-2

216
Q

Baffles are provided in a shell and tube heat exchanger to increase the turbulence and velocity of the shell side fluid. Which of the following shaped baffles does not fall in the category of transverse baffle ?

A

Flat plate extending across the wall

217
Q

A certain pressure vessel manufacturer avoids doing reinforcements calculations for openings by always providing a reinforcing pad extending upto double the diameter of the opening and of the same material and thickness as that of the shell wall. If area compensation is accepted as a code guideline, his approach leads to safe design

A

irrespective of the shape of the vessel.

218
Q

In a __________ rivetted joint, the number of rivets decreases from the innermost row to the outermost row.

A

diamond

219
Q

Large process vessels operating under extreme temperature and pressure conditions are normally clad/ lined with materials like stainless steel, aluminium, nickel & its alloys, copper & its alloys and titanium. The cladding thickness is generally about __________ percent of the total thickness.

A

10 to 20

220
Q

Heat transfer co-efficient for a horizontal condenser as compared to a vertical condenser operating under similar conditions is

A

about 3 times

221
Q

Pick out the wrong statement pertaining to the design of the distillation column.

Generally, a skirt clerance of 0.5” to 1.5’ is recommended to prevent plugging of the slots by residue build up.
The purpose of the slot is to disperse the gas into the liquid in the form of small bubbles.
If sufficient slot area is not provided, the gas may pass through the skirt clearance.
none of these.

A

none of these.

222
Q

The longitudinal stress induced in a thin walled cylinderical vessel under internal pressure is

A

pd/8t

223
Q

In distillation columns, bubble caps are held in place over trays by

A

both (b) and (c)

a hold down bar
bolts

224
Q

The buckling tendency of compression members is always in the direction of the

A

least radius of gyration.

225
Q

In case of plain carbon steel, butt welded joints are used for shell plate thickness ≤ __________ cms.

A

3.8

226
Q

The average velocity in the tubes of a 1-4 heat exchanger is __________ times that in 1-1 heat exchanger having the same size & number of tubes and operated at same liquid flow rate.

A

4

227
Q

Hoop (circumferential) stress induced in a thin walled ‘Horton Sphere’ used for the storage of liquid ammonia under pressure is

A

pD/2t

228
Q

When one of the fluids is highly corrosive and has fouling tendency, it should

A

preferably flow inside the tube for its easier internal cleaning.

228
Q

The raio, propeller dia/tank dia is normally taken as

A

0.15-030

229
Q

A/an __________ is used for changing the direction of a pipeline.

A

elbow

230
Q
A
231
Q

Maximum plate efficiency is achieved in case of __________ flow.

A

cross

231
Q

The LMTD correction factor (FT) is defined as the

A

ratio of true temperature difference to the LMTD.

232
Q

The clearance between two tubes in a shell and tube heat exchanger is known as ‘ligament’, whose minimum value is __________ the outside diameter of the tube, but in no case it should be less than 4.5 mm

A

one fourth

233
Q

Normally, the length to diameter ratio of rotary dryers varies form 4 to 10 and for its economic operation, the number of transfer units (NTU) for such dryers varies from

A

1.5-2.5

233
Q

The ratio for the rate of washing to the final rate of filtration in a washing type of plate and frame filter is

A

0.25

233
Q
A
234
Q
A
234
Q

Value of Peclet number = 0, is the representative of

A

complete back mixing.

235
Q

Poisson’s ratio of a material is the ratio of unit lateral strain to the unit axial elongation within its elastic limit. The value of Poisson’s ratio for structural and pressure vessel steel may be taken as

A

0.3

236
Q

Removable connection of tubes to tube sheet is called

A

ferrule

236
Q

Stress-strain diagram for low carbon steel/mild steel is shown below in the Fig.

The point ‘A’ on the Fig. represents the

A

elastic limit

237
Q

Typical static submergence for bubble cap plate column operating at atmospheric pressure may be around

A

0.5”

237
Q

In the allocated cap area, bubble caps are generally arranged on equilateral triangular pitch. Number of caps fixed on a plate is with a

A

either ‘a’ or ‘b’.

clearance of 25-75 mm.
cap pitch of 1.3-2 times the cap diameter.

238
Q

The length of straight rectangular weir used on cross-flow trays is generally __________ the column diameter.

A

0.6-0.8 times

239
Q

What is the slope of the operating line in the rectifying section of a distillation coloumn ?

A

<1

240
Q

L/D for couplings and unions would be

A

0

241
Q

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

A

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

241
Q
A
241
Q
A
241
Q
A
241
Q
A

indiabix (11 decks)

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