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(IB) Process Equipment & Plant Design > Section 2 > Flashcards

Section 2 Flashcards

1
Q

Needle valves are generally not used for

A

very large diameter pipes.

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2
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. flow rates of each fluid.
B. type and size of packing.
C. concentration of each fluid.
D. all a, b & c.

A

D

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3
Q

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

A

A

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4
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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5
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.

CDS, CTS

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6
Q

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

A

Allowable vapour velocity.

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7
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. is more accurate in finding the number of equilibrium stages.
B. accounts for the enthalpy changes in the process.
C. facilitates direct calculation of heat load on reboiler & condenser from, the diagram used in this method.
D. all ‘a’, ‘b’ & ‘c’.

A

D

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8
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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9
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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10
Q

Saddle supports are used for supporting __________ vessels.

A

horizontal cylinderical

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11
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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12
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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13
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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14
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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15
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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16
Q

The maximum liquid gradient over a tray must not exceed

A

0.5” -1.25”

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17
Q

An underdesigned steam trap will

A

back up condensate and cause water hammer in steam line.

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18
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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19
Q

Speed of industrial paddle agitator ranges from __________ rpm.

A

20 to 100

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20
Q

__________ strain is measured using a ‘strain rosetter’.

A

Linear

21
Q

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

A

radial

22
Q

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

A

fixed charges initially

23
Q

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

A

∞

24
Q

Vertical vessels are not supported by

A

saddles

25
Q

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

A

increase

26
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.

27
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.

28
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.

29
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 secon

30
Q

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

A

30

31
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

32
Q

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

A

chain

33
Q

Pick out the wrong statement:
A. The tensile strength of a brittle material is less than its compressive strength.
B. The compressive strength of a ductile materia] is less than its tensile strength.
C. In a thick cylindrical shell, the hoop stress is maximum at the inner radius.
D. The value of crushing load is more than that of buckling load for long colmns.

A

D

34
Q

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

A

D

35
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.

36
Q

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

A

pd/2t

37
Q

Le/D for fully open gate valves would be
A. much more than that for fully open globe valves.
B. much less (say 2% than that for fully open globe valves).
C. around 7.
D. both (b) and (c).

A

D

38
Q

LMTD correction factor is used in heat exchanger design for

A

multipass shell and tube heat exchanger.

39
Q

Floating head heat exchangers are used for the

A

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

40
Q

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

A

6” dia cap with 4” dia riser.

41
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

42
Q

In case of a continuous distillation column, increase in reflux ratio may result in the
A. lower fixed charges for the column.
B. greater cost for the reboiler heat supply.
C. greater cost for the condenser coolant.
D. all (a), (b) and (c).

A

D

43
Q

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

A

8

44
Q

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

A

more

45
Q

Which of the following factors affect the pressure drop in a co-current gas-liquid absorption packed tower ?
A. Size, shape, orientation and surface of the packing particles.
B. Density and viscosity of fluids.
C. Fluid flow rates.
D. All (a), (b) and (c).

A

D

46
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

47
Q

Rivets are generally specified by the

A

shank diameter

48
Q

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

A

4 to 10

(IB) Process Equipment & Plant Design (8 decks)

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