Process Equipment and Plant Design (Set 4)

Question 1

Cylindrical storage tanks used for the storage of volatile liquids (e.g., naphtha) have ____ roofs.

Answer 1

floating

Question 2

Larger depth of liquid on the trays of a distillation column

Answer 2

both (a) & (b).

(leads to high tray efficiency.) & (results in higher pressure drop per tray.)

Question 3

Pick out the wrong statement.
a. Plate efficiency increases with increase in superficial vapour velocity till entrainment limit.
b. Increase in depth of the liquid about the slots increases the plate efficiency, particularly if the liquid depth is < 1”.
c. Too small a plate spacing can cause a low efficiency, if the vapour velocity is greater than the allowable value.
d. none of these.

Answer 3

none of these.

Question 4

Pick out the wrong statement.

a. In practical operation, distillation towers having diameter 3-6 metres equipped with bubble cap (round) size of 15 cms are used.

b. Height of packing in a packed tower is about 3 times the column diameter for raschig rings and about 5 to 10 times the column diameter for saddle packing.

c. In a seive tray, the minimum hole diameter is equal to the tray thickness.

d. In a stainless steel seive tray, the minimum hole diameter is equal to 10 times the plate thickness.

Answer 4

In a stainless steel seive tray, the minimum hole diameter is equal to 10 times the plate thickness.

Question 5

In the downcomer of a distillation column, the minimum recommended residence time is about ____ seconds.

Answer 5

5

Question 6

For identical situation, condensing film coefficient in case of a horizontal condenser is almost ____ the value expected in case of vertical condenser.

Answer 6

thrice

Question 7

Diameter of rivet hole (d, mm) and the plate thickness (t, mm) are related by Unwin’s formula as

Answer 7

d = 1.6 sqrt(t)

Question 8

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

Answer 8

positive

Question 9

In which of the following evaporators, steam is fed inside the tube while the liquor is outside the tube?

Answer 9

Horizontal tube evaporator

Question 10

A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of

Answer 10

2^0.8

Question 11

In a multipass shell and tube heat exchanger, the baffles on shell side is primarily provided for

Answer 11

creating turbulence.

Question 12

For turbine agitator, the impeller diameter is about

Answer 12

0.3 to 0.5 d

Question 13

In a shell and tube heat exchanger having triangular pitch, the shell side equivalent diameter is given by

Answer 13

https://www.indiabix.com/_files/images/chemical-engineering/process-equipment-and-plant-design/570-146-1.png

Question 14

If a single tube pass heat exchanger is converted to two passes; for the same flow rate, the pressure drop per unit length in tube side will ____ times.

Answer 14

increase by 2^1.6

Question 15

Pick out the wrong statement.

Answer 15

A 90° welded elbow is diagrammatically represented by https://www.indiabix.com/_files/images/chemical-engineering/process-equipment-and-plant-design/580-290-3.png

Question 16

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

a. Tube dia is 3-6 cms, while tube length in 3-6 metres.
b. Steam is fed to the shell, whereas the liquor is filled inside the tube.
c. Liquor level is maintained at l/3rd to 1/2 of the height of the tube.

Answer 16

none of these.

Question 17

Which of the following is the most common type of baffle used in industrial shell and tube heat exchanger?

Answer 17

25% cut segmental baffle.

Question 18

What is the minimum recommended ligament for square pitch arrangement in case of heat exchangers?

Answer 18

6.5 mm

Question 19

Pick out the correct statement

a. Centre to centre distance between two consecutives rivets in a row is called the pitch.
b. A rivetted joint made in overlapping plates is called butt joint.
c. Hole size drilled in rivetted plates is less than the actual size of the rivet.

Answer 19

Centre to centre distance between two consecutives rivets in a row is called the pitch.

Question 20

Safety valves are provided in chemical equipments to guard against excessive

Answer 20

pressure/pressure fluctuation

Question 21

The equivalent diameter for pressure drop is ____ that for heat transfer.

Answer 21

smaller than

Question 22

Most of the storage vessels/tanks are made cylindrical, because of the fact that a cylinder

Answer 22

both (a) and (b).

has greater structural strength and is easy to fabricate.

Question 23

The distance between the top of the slots and the liquid surface when the static liquid is just ready to flow over the overflow weir is called

Answer 23

static submergence

Question 24

Liquid gradient over the tray results due to the

Answer 24

resistance offered to flow of liquids by caps & risers and the flow of gas.

Question 25

The centre to centre distance between two consecutive baffles in a shell and tube heat exchanger is called the baffle pitch or baffle spacing, which is more than 1/5th the I.D. of the shell. Which of the following is not a function of the baffles?

Answer 25

To increase the tube side heat transfer co-efficient by inducing turbulence.

Question 26

A high vapour velocity is required for high plate efficiency in a seive plate coloumn. The satisfactory value of operating vapor velocity for design purpose in seive plate column is about ____ percent of the flooding velocity.

Answer 26

80

Question 27

The approximate liquid depth in an agitation tank is equal to (where, d = tank diameter)

Answer 27

d

Question 28

Baffle width is normally taken as ____ times the tank diameter.

Answer 28

0.1-0.12

Question 29

A cylinderical pressure vessel of volume 6 ?m3 has to be designed to withstand a maximum internal pressure of 10 atm. The allowable design stress of the material is 125N/mm2 and corrosion allowance is 2 mm. The thickness of the vessel for a length/diameter ratio of 3 will be close to

Answer 29

10 mm

Question 30

Which of the following packing materials provides for maximum mass transfer?

Answer 30

Cross-partition rings.

Question 31

____ of water makes it a widely used coolant in heat exchangers.

Answer 31

High specific heat

Question 32

The equivalent diameter for fluid flow through a channel of constant non-circular cross section of area 'A' is given by (where, P = perimeter of the channel in contact with the fluid)

Answer 32

4 A/P

Question 33

Fouling factor must be included in the calculation of over all design heat transfer coefficient, when the liquid

Answer 33

containing suspended solids flows at low velocity.

Question 34

Lug support is meant for supporting ____ vessels.

Answer 34

small

Question 35

Overall mass transfer co-efficient in case of absorption of ____ in water is based on the gas film co-efficient only, as the mass transfer process is gas film (phase) controlling.

Answer 35

NH3

Question 36

Which tube arrangement in a heat exchanger would facilitate highest heat transfer rate?

Answer 36

Triangular pitch.

Question 37

In case of 1.5" heat exchanger tubes, the inside flow area ____ with decrease in BWG.

Answer 37

decreases

Question 38

Cylindrical pressure vessels in horizontal condition is generally supported on a ____ support.

Answer 38

saddle

Question 39

Pressure drop per tray in the atmospheric distillation column is about ____ psi.

Answer 39

0.07 - 0.12

Question 40

Welded joint efficiency in the design of chemical process equipment is taken as

Answer 40

0.85

Question 41

The thickness of segmental baffles (25 -35% cut truncated plates usually) is generally ____ the tube wall thickness.

Answer 41

twice

Question 42

The safe height (h) to diameter (d) ratio (i.e., h/d) for liquid/petro fuel storage tank of capacity more than 45 kilolitres is less than

Answer 42

1

Question 43

For given number of passes, pitch & tube diameter, the maximum number of tubes that can be accommodated in a shell of tripled inside diameter will be ____ times.

Answer 43

considerably more than 9

Question 44

The ratio of linear stress to linear strain is termed as the

Answer 44

modulus of elasticity

Question 45

____ head is the most economical for cylindrical vessels designed for operating at high pressure (> 15 atm.).

Answer 45

Ellipsoidal

Question 46

Bubble cap plate column is

Answer 46

a finite stage contactor.

Question 47

In seive plate column, holes are drilled or punched in sizes ranging from 2.5 to 12 mm (5 mm being widely used). The hole pitch is normally ____ times the hole diameter to give the required hole area.

Answer 47

2.5 to 4.0

Question 48

Pick out the wrong statement. a. Rivetting provides a permanent fastening method. b. The joint made by overlapping of one plate over the other, and then rivetting the two plates together with two rows of rivets is called 'double rivetted butt joint'. c. Shank diameter of the rivets should be less than the size of the hole drilled in the plate for rivetting. d. The efficiency of a rivetted joint is the ratio of the strength of the rivetted joint to the strength of the solid plate.

Answer 48

The joint made by overlapping of one plate over the other, and then rivetting the two plates together with two rows of rivets is called 'double rivetted butt joint'.

Question 49

The force due to wind load acting on a tall vessel depends upon its a. shape b. outside diameter. c. height.

Answer 49

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

Question 50

Bubble cap diameter used for the distillation column having diameter ranging from 1.5 to 4.5 metres is about ____ mm.

Answer 50

100

Question 51

Power required for agitation depends upon the a. height & properties of the liquid. b. agitator type & speed of agitation. c. size of agitator & the tank.

Answer 51

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

Question 52

Tube height in a calendria type evaporator is normally less than ____ metres.

Answer 52

2

Question 53

Pick out the wrong statement. a. Lug supports are less expensive than other type of supports. b. A pipe is differentiated from a tube by the fact that a pipe has a greater wall thickness compared to the tube. c. A reducer is used to change the direction of a pipe in a straight run. d. The method of fixing tubes to a tube sheet by expanding is called 'tube rolling'.

Answer 53

A reducer is used to change the direction of a pipe in a straight run.

Question 54

For a 25 mm hole drilled in plates to be rivetted, the shank diameter of the rivet should be ____ mm.

Answer 54

23

Question 55

In a shell and tube heat exchanger having square pitch, the shell side equivalent diameter is given by (where, P = pitch, d = outside diameter of the tube)

Answer 55

https://www.indiabix.com/_files/images/chemical-engineering/process-equipment-and-plant-design/570-145-1.png

Question 56

Optimum economic pipe diameter for fluid flow is determined by the

Answer 56

total cost considerations (pumping cost plus fixed cost of the pipe).

Question 57

Pressure differential maintained across a continuous rotary vacuum filter is in the range of ____ mm Hg column.

Answer 57

250 to 500

Question 58

Vertical storage vessels are never supported by ____ support.

Answer 58

saddle

Question 59

In a double pipe (concentric) heat exchanger, the hydraulic radius for heat transfer (for a fluid flowing through the annulus) would be

Answer 59

more than that for fluid flow.

Question 60

Elastic failure of a material occurs, when the tensile stress equals yield strength, yield point or the elastic limit. Also, the elastic failure occurs according to maximum strain theory, when the maximum tensile strain equals (where, σ = yield strength and E = modulus of elasticity)

Answer 60

σ/E

Question 61

In a pressure vessel containing multiple openings of various dimensions at different parts, stress concentration at the edges of the opening is maximum which becomes negligibly small beyond the area covered by ____ times the hole diameter.

Answer 61

two

Question 62

What is the slope of the feed line, if the feed to a distillation column is a saturated liquid?

Answer 62

∞

Question 63

Filtration rate is affected by the a. pressure drop across the cake & filter medium. b. cake & filter medium resistance. c. area of filtering surface & the viscosity of filtrate.

Answer 63

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

Question 64

Liquid gradient over a tray can be minimised by a. providing a higher skirt clearance or a higher weir. b. decreasing the number of rows of caps through which the liquid flows or by decreasing the velocity of liquid flow past the caps or by reducing the distance along the tray through which the liquid must flow. c. using split flow, radial flow or cascade flow for column diameter large than 4 ft.

Answer 64

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

Question 65

In a shell and tube heat exchanger for a given heat transfer surface area, smaller diameter tubes are favoured as compared to larger diameter ones ; because the smaller diameter tubes

Answer 65

can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less.

Question 66

Le/D for 90° elbow (medium radius) and 90°square elbow would be respectively around

Answer 66

25 and 60

Question 67

____ heat exchanger is also known as 'hair pin type' exchanger,

Answer 67

Double pipe

Question 68

What is the value of 'q' for saturated vapor feed to a distillation column ?(where q = fraction of the feed stream that is liquid.)

Answer 68

0

Question 69

In hydrostatic testing of welded pipe (for leakage, strength etc.) the ratio of minimum hydrostatic test pressure to internal design pressure is around

Answer 69

1.5

Question 70

Frame thickness in the plate and frame filter press is normally in the range of ____ inches.

Answer 70

0.25 to 8

Question 71

Cylinderical shell thickness of rotary drier is generally ____ mm.

Answer 71

6-8

Question 72

The ratio of lateral strain to linear strain is termed as the

Answer 72

Poisson's ratio

Question 73

The distance between the centre of a rivet hole to the nearest edge of the plate is called

Answer 73

margin

Question 74

Mc Cable Thiele method used for finding theoretical stages in a distillation column assumes that the a.sensible heat differences are small, because the temperature changes from tray to tray is small. b. Trouton's rule is applicable. c. liquid/vapor loading across the column remains constant.

Answer 74

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

Question 75

A minimum clearance of about ____ mm is maintained between the distillation column wall and the bubble cap.

Answer 75

38

Question 76

Pick out the wrong statement. a. If sufficient residence time (around 8 seconds) is not proivided to the downcoming liquid in the downcomer, it may entrain some vapour. b. The liquid head in the downcomer should not be greater than one half the plate spacing to avoid flooding. c. The dischare end of the downcomer must project far enough into the tray liquid so that no gas bubbles can enter the open end and by pass the bubble caps.

Answer 76

none of these.

Question 77

Pick out the wrong statement pertaining to shell and tube heat exchanger. a. Clearance between shell & baffles and between tube & baffles should be minimum to avoid by-passing of the fluid, but it should be enough to permit the removal of tube bundle. b. Baffles are supported independently of the tubes by tie rods and positioned by spacers. c. Tie rods are fixed at one end in the tube sheet by making blind holes and the minimum number of tie rods is 4 with at least 10 mm diameter. d. Bracket supports are used for horizontal shell, while saddle support is used for vertical shell.

Answer 77

Bracket supports are used for horizontal shell, while saddle support is used for vertical shell.

Question 78

Wind load consideration in the design of a support can be neglected, when the vessel is

Answer 78

short (< 2 m) and housed indoor.

Question 79

Souders Brown equation given by, https://www.indiabix.com/_files/images/chemical-engineering/process-equipment-and-plant-design/590-379-1.png , is used for the calculation of the ____ in a continuous distillation column.

Answer 79

diameter of the bubble cap column

Question 80

The ratio of volumes of the mixed reactor to the plug flow reactor (for identical feed composition, flow rate, conversion, and for all positive reaction orders) is always

Answer 80

> 1

Question 81

Steam economy is defined as the amount of evaporation per unit amount of steam used, while the capacity is the total evaporation obtained per hour. Use of multiple effect in evaporation a. increases capacity. b. increases economy. c. does not affect the capacity.

Answer 81

both 'b' & 'c'.

Question 82

Le/D for a Tee (used as elbow, entering run) would be around

Answer 82

60

Question 83

Log mean temperature difference in case of multi-pass shell and tube heat exchanger is always

Answer 83

less than arithmetic mean value.

Question 84

Practical dividing line between a ductile and brittle materials is suggested, when the ultimate elongation is about 5%. Generally, larger the knuckle radius, stronger is the corner torus section of a head. The knuckle radius provided should be less than ____ of the head. a. 6% of I.D. b. 3 times the thickness

Answer 84

either (a) or (b), whichever is larger

Question 85

Tubes are fixed to the tube sheet (a thick circular metallic plate) by the method of tube rolling and brazing (non-removable) or ferrule connection (removable). Thickness of the tube, sheet is normally ____ the outside diameter of the tube but in no case it should be less than 22 mm (7/8").

Answer 85

equal to

Question 86

A shell may by termed as thin if its thickness to diameter ratio is less than 0.1. The factor which can be neglected in the calculation of membrane stresses is

Answer 86

bending

Question 87

Scale up problem in design based on the similarity concept takes into account ____ similarity. a. geometrical b. kinematic c. dynamic

Answer 87

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

Question 88

____ closure is the weakest enclosure for cylindrical vessels.

Answer 88

Conical or flat plate

Question 89

Which of the following efficiencies can be greater than 100%?

Answer 89

Murphree plate efficiency.