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ChELE Concept > Process Equipment and Plant Design > Flashcards

Process Equipment and Plant 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

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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7
Q

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

A

increases

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8
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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9
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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10
Q

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

A

elastic limit

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11
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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12
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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13
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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14
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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15
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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16
Q

A rivetted joint does not fail by __________ of rivets.

A

none of these

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17
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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18
Q

Bracket supports are the most suitable for supporting __________ vessels.

A

thick walled vertical

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19
Q

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

A

inside diameter

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20
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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21
Q

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

A

60°

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22
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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23
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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24
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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25
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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26
Q

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

A

Cross flow

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27
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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28
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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29
Q

Pick out the correct statement.

A

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

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30
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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31
Q

A stuffing box is used for

A

prevention of fluid leakage around moving parts.

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32
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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33
Q

Needle valves are generally not used for

A

very large diameter pipes.

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34
Q

Pick out the wrong statement. (for HEx)

A

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

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35
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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36
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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37
Q

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

A

Allowable vapour velocity

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38
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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39
Q

Saddle supports are used for supporting __________ vessels.

A

horizontal cylinderical

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40
Q

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

A

0.2 D

41
Q

The maximum liquid gradient over a tray must not exceed

A

0.5” -1.25”

42
Q

An underdesigned steam trap will

A

back up condensate and cause water hammer in steam line

43
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)

44
Q

__________ strain is measured using a ‘strain rosetter’.

A

Linear

45
Q

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

A

radial

46
Q

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

A

fixed charges initially

47
Q

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

A

∞

48
Q

Vertical vessels are not supported by

A

saddles

49
Q

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

A

increase

50
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

51
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.

52
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.

53
Q

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

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.

54
Q

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

A

30

55
Q

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

A

chain

56
Q

Pick out the wrong statement:

A

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

57
Q

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

A

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

58
Q

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

A

pd/2t

59
Q

LMTD correction factor is used in heat exchanger design for

A

multipass shell and tube heat exchanger

60
Q

Floating head heat exchangers are used for the

A

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

61
Q

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

A

6” dia cap with 4” dia riser.

62
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

63
Q

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

A

8

64
Q

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

A

more

65
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

66
Q

Rivets are generally specified by the

A

shank diameter

67
Q

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

A

4 to 10

68
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

69
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

70
Q

The dust collection efficiency of a cyclone separator

A

none of these.

71
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

72
Q

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

A

A vapor phase reactor.

73
Q

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

A

density of the gas and inversely as viscosity of the gas

74
Q

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

A

all multipass

75
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.

76
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

77
Q

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

A

3 to 12.5

78
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

79
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

80
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.

81
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

82
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

83
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

84
Q

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

A

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

85
Q

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

A

high latent heat.

86
Q

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

A

Conical

87
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 .

88
Q

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

A

1.25-1.50 times

89
Q

Accidents in chemical plants are mostly due to

A

faulty operating procedures

90
Q

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

A

bubble cap

91
Q

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

A

Permissible slot velocity

92
Q

Pick out the wrong statement about distillation operation

A

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

93
Q

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

A

Copper

94
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”.

95
Q

Diameter of the seive tray column is determined by the

A

upper limit of the vapour velocity

96
Q

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

A

decreases.

97
Q

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

A

12.5

98
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.

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