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ED & PD > S6 > Flashcards

S6 Flashcards

1
Q

The minimum plate spacing in most of the pertroleum refinery distillation columns (of dia > 3 ft) is normally ________ inches.

A

18

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2
Q

Joint efficiency (J) for a seamless pipe is

A

1

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3
Q

For a given design of bubble cap, the number of bubble caps to be used per tray is set by the

A

allowable gas velocity through the slots.

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4
Q

The shell side pressure drop in a shell and tube heat exchanger is maximum for ________ baffle.

A

orifice

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5
Q

The function of manholes provided in the shell of a distillation column is to

A

give access to the individual trays for cleaning, maintenance and installation.

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6
Q

Back-trapping in a distillation column results due to

A

excessive liquid gradient over the tray.

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7
Q

For a cylinderical vessel of moderate height, the weld joint efficiency for joints parallel to the cylinderical axis is given as 1.0, while for joints along the girth (circumference) it is given as 0.8. In calculating the shell wall thickness using code formula for an internally pressurised cylinderical vessel, what value of weld joint efficiency should be used?

A

0.8

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8
Q

Diameter of bubble caps used in high pressure columns is ________ as compared to that used in identical vacuum columns.

A

more

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9
Q

The ideal size of round bubble caps to be used in industrial distillation column having a diameter of 3-6 metres is __________ cms.

A

15

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10
Q

Lap joints are preferred for plates having thickness ________ mm.

A

> 3

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11
Q

In a distillation column, minimum clearance to be maintained betweeen the overflow weir and the last row of the bubble caps is __________ cms.

A

7.5

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12
Q

Which of the following lengths of heat exchanger tubes are normally not used in practice?

A

10 metres

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13
Q

In case of a shell and tube heat exchanger, the effect of L/D on inside film heat transfer co-efficient (hi) vanishes after a Reynold number of

A

10000

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14
Q

Equivalent diameter for heat transfer calculation for a duct of square cross-section having each side as ‘d’ will be

A

d

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15
Q

A cylindrical storage tank can have a self supported conical roof,

A

if its diameter is less than 15-20metres.

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16
Q

For high pressure process equipments/vessels, the connected nozzle should be

A

flanged

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17
Q

Smoker’s equation for the calculation of number of equilibrium stages in a continuous binary distillation column is used, when the

A

relative volatility is close to one (e.g., separation of close boiling isomers).

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18
Q

Column support for the roof of cylindrical storage tank must be provided for

A

large diameter tanks.

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19
Q

For a cylinderical internally pressurised vessel, which of the following closure types would withstand highest pressure, if each closure is of the same material and thickness?

A

ellipsoidal (2 : 1)

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20
Q

In inclined long tube vertical evaporators, the tubes are inclined at an angle of

A

45°

21
Q

In a continuous distillation column, the optimum reflux ratio ranges from __________ times the minimum reflux ratio.

A

1.1 to 1.5

22
Q

The wall thickness for a large high pressure pipeline is determined by the consideration of the

A

circumferential pipewall tension.

23
Q

In the case of a shell and tube heat exchanger, the logarithmic mean temperature difference

A

is always less than arithmetic average value.

24
Q

Skirt support is the most suitable for supporting __________ vessels.

A

tall vertical

25
Q

Baffles may be eliminated for

A

high viscosity liquids (> 600 poise).

26
Q

Generally, as the length of the liquid path on a tray is increased beyond 5 ft, the overall column efficiency

A

increases

27
Q

In packed absorption tower, onset of flooding usually occurs at a pressure drop of about __________ mm of water column per metre height of packing

A

50-75

28
Q

For pipe flows, head is proportional to __________ at constant capacity (where D = pipe diameter).

A

1/D^5

29
Q

Friction factor for turbulent flow in a new pipe is given by

A

f = 0.04 / (NRe)^0.16

30
Q

The minimum tray spacing in distillation column of diameter less than 3 ft is normally __________ inches.

A

6

31
Q

Oxygen carrying pipelines in chemical industries are coloured with __________ colour.

A

blue

32
Q

Normally, the ratio of the total riser area to the tower cross sectional area (for bubble cap towers of diameter more than 3 ft) is around

A

0.1-0.2

33
Q

Pick out the wrong statement about the design of seive plate column and the bubble cap column.

A

Weir height for a bubble cap plate column is the same as that for a seive plate column.

34
Q

Maximum size of the raschig rings used in a packed tower is about __________ of the coloumn diameter.

A

1/30th

35
Q

Longitundinal stress induced in a thin walled cylindrical storage vessel is

A

pD/4t

36
Q

The type of stress developed in a metallic bar on subjecting it to a change in temperature without allowing it to be deformed is __________ stress.

A

thermal

37
Q

The safe distance of habitation from a hazardous chemical plant (TLV of its product < 1000 ppm) should be about __________ kms.

A

25

38
Q

Pick out the wrong statement pertaining to a shell and tube heat exchanger.

A

Disk and doughnut baffle is the most commonly used baffle.

39
Q

Maximum allowable vapour velocity in a bubble cap tower is determined by the

A

entrainment considerations.

40
Q

Normally, the plate thickness of the bottoms and roofs of vertically cylindrical storage vessels as compared to that of the cylindrical shell is

A

less

41
Q

The practical representative values of HETP for a number of commercial operations lies within a range of __________ metre.

A

0.4-0.9

42
Q

Of the pressure vessels, with same thickness but different diameters, which one withstands higher pressure?

A

Smaller dia vessel.

43
Q

Reflux ratio variation in a distillation column is between

A

minimum and infinity

44
Q

Width and depth of grooves in the tube sheet holes normally are __________ inch respectively.

A

1/8 and 1/64

45
Q

In condenser, the cooling water is passed in the tube side in a pass arrangement, because

A

it reduces heat transfer area.

46
Q

In packed towers provided with pall rings liquid redistributors are positioned at heights of every 6 metres or 5-10 times the column diameter, whichever is less. Maximum size of the pall rings should not exceed __________ of the column diameter.

A

1/10-1/15th

47
Q

Height of the flights in the rotary drier is in the range of

A

0.08 to 0.12 d

48
Q

Vapor velocity in a distillation column for non-foaming mixture is in the range of __________ times the flooding velocity.

A

0.6 to 0.7

ED & PD (8 decks)

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