Section 1 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. the most suitable for thick vertical vessel.
B. same as bracket support.
C. provided usually for vessels of much smaller height than skirt supported vessels.
D. all (a), (b) and (c).

A

D

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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 F(t)

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

A

B

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

A

D

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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

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.

22
Q

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

A

0.80

23
Q

A rivetted joint does not fail by __________ of rivets.
A. tearing
B. shearing
C. tearing of the plate across a row
D. none of these

A

D

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.

25
Q

Bracket supports are the most suitable for supporting __________ vessels.

A

thick walled vertical

26
Q

In a multipass shell and tube heat exchanger, the shell side cross flow area does not depend upon
A. baffle spacing
B. clearance
C. pitch
D. none of these

A

D

27
Q

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

A

inside diameter

28
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

29
Q

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

A

D

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

31
Q

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

A

60°

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

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

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.

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

36
Q

36.
__________ tray arrangement is recommended for distillation column having diameter upto 4 ft.

A

Cross flow

37
Q

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

A

1

38
Q

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

A

D

39
Q

The main purpose of providing stepping on the trays is to

A

facilitate handling of large flow rate of liquid.

40
Q

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

A

50-150

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

42
Q

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

A

Di, opt = 3 Q0.36 ρ0.18

43
Q

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

A

B

44
Q

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

A

less

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.

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. The pressure drop due to the caps & slots and the static submergence should be as high as practicable for reasonable operation.
B. 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.
C. The dimensionless ratio of liquid gradient to pressure drop head caused by the bubble cap assembly should be less than 0.4.
D. none of these.

A

D

47
Q

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

A

0.1 to 2

48
Q

A stuffing box is used for

A

prevention of fluid leakage around moving parts.

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 = G^2

50
Q

Pick out the wrong statement.
A. 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.
B. filling ratio for dispersing gas in a liquid is 2 for sufficiently long contact period.
C. flat bottom and conical bottom vessels have low agitation efficiency for agitation of heavy solids in liquids.
D. dished bottom vessel has very high power consumption.

A

D