Process Equipment and Plant Design

Question 1

Fresh water carrying pipelines in chemical industries are coloured with __________ color.

Answer 1

sea green

Question 2

Which of the following material is seldom used for pressure vessel construction ?

Answer 2

Rimmed steel

Question 3

The ratio of shear stress to shear strain is called

Answer 3

shear modulus

Question 4

25 per cent cut segmental baffle means that the baffle

Answer 4

height is 75% of the I.D. of the shell.

Question 5

Liquid/petroleum fuel storage tanks are built underground (as in case of petrol pumps), when the storage capacity is less than __________ kilolitres.

Answer 5

45

Question 6

Pick out the wrong statement pertaining to the use of valve tray, seive tray and bubble cap trays in continuous distillation column.

Answer 6

Maintenance cost for valve and seive trays are comparatively more than bubble cap tray due to their relatively complicated construction features.

Question 7

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

Answer 7

increases

Question 8

Holes of a sieve tray are arranged in triangular pitch of __________ times the hole diameter.

Answer 8

2.5 to 5

Question 9

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.

Answer 9

5-11

Question 10

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

Answer 10

elastic limit

Question 11

In a shell and tube heat exchanger, the ‘tube pitch’ is defined as the

Answer 11

shortest centre to centre distance between adjacent tubes.

Question 12

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 ?

Answer 12

Reflux is not a saturated liquid.

Question 13

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

Answer 13

(1.2)5/3

Question 14

Where does the maximum tensile strength occur in a thick cylindrical vessel subjected to internal pressure ?

Answer 14

At the inner surface

Question 15

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

Answer 15

0.80

Question 16

A rivetted joint does not fail by __________ of rivets.

Answer 16

none of these

Question 17

Triangular pitch tube layout as compared to square pitch in a shell and tube heat exchanger

Answer 17

permits the use of more tubes in a given shell diameter.

Question 18

Bracket supports are the most suitable for supporting __________ vessels.

Answer 18

thick walled vertical

Question 19

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

Answer 19

inside diameter

Question 20

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.

Answer 20

20

Question 21

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

Answer 21

60°

Question 22

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.

Answer 22

75

Question 23

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

Answer 23

less

Question 24

Correct use of ‘factor of safety’ is very important in equipment design. It is defined as the ratio of the

Answer 24

ultimate stress to working stress.

Question 25

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.

Answer 25

20-40

Question 26

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

Answer 26

Cross flow

Question 27

The main purpose of providing stepping on the trays is to

Answer 27

facilitate handling of large flow rate of liquid

Question 28

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.

Answer 28

Ellipsoidal

Question 29

Pick out the correct statement.

Answer 29

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

Question 30

Pick out the wrong statement pertaining to the design of a basket type evaporator.

Answer 30

It is used for high viscosity liquor having large rate of scaling.

Question 31

A stuffing box is used for

Answer 31

prevention of fluid leakage around moving parts.

Question 32

Pick out the wrong statement. In an agitated vertical cylinderical reaction vessel, the

Answer 32

dished bottom vessel has very high power consumption.

Question 33

Needle valves are generally not used for

Answer 33

very large diameter pipes.

Question 34

Pick out the wrong statement. (for HEx)

Answer 34

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

Question 35

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

Answer 35

decreases

Question 36

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

Answer 36

central dished section and corner torus section

Question 37

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

Answer 37

Allowable vapour velocity

Question 38

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

Answer 38

smaller reactor should come first.

Question 39

Saddle supports are used for supporting __________ vessels.

Answer 39

horizontal cylinderical

Question 40

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

Answer 40

0.2 D

Question 41

The maximum liquid gradient over a tray must not exceed

Answer 41

0.5" -1.25"

Question 42

An underdesigned steam trap will

Answer 42

back up condensate and cause water hammer in steam line

Question 43

The slope of the feed line in distillation opeartion is given by (where, q = fraction of the feed stream that is liquid.)

Answer 43

-q/(1-q)

Question 44

__________ strain is measured using a 'strain rosetter'.

Answer 44

Linear

Question 45

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

Answer 45

radial

Question 46

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

Answer 46

fixed charges initially

Question 47

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

Answer 47

∞

Question 48

Vertical vessels are not supported by

Answer 48

saddles

Question 49

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

Answer 49

increase

Question 50

Spherical shaped pressure vessel is considered to be the most ideal, because it can

Answer 50

withstand higher pressure for a given metallic shell thickness

Question 51

An adequate clearance between the tray and the shell wall of a distillation column is provided to

Answer 51

allow for thermal expansion and facilitate installation.

Question 52

Overall tray efficiency of a distillation column is the ratio of the number of

Answer 52

ideal trays required to the number of real trays required.

Question 53

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

Answer 53

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.

Question 54

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

Answer 54

30

Question 55

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

Answer 55

chain

Question 56

Pick out the wrong statement:

Answer 56

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

Question 57

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

Answer 57

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

Question 58

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

Answer 58

pd/2t

Question 59

LMTD correction factor is used in heat exchanger design for

Answer 59

multipass shell and tube heat exchanger

Question 60

Floating head heat exchangers are used for the

Answer 60

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

Question 61

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

Answer 61

6" dia cap with 4" dia riser.

Question 62

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.

Answer 62

nozzle or rim

Question 63

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

Answer 63

8

Question 64

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

Answer 64

more

Question 65

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.

Answer 65

1.25 to 3.125

Question 66

Rivets are generally specified by the

Answer 66

shank diameter

Question 67

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

Answer 67

4 to 10

Question 68

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.

Answer 68

19

Question 69

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.

Answer 69

600

Question 70

The dust collection efficiency of a cyclone separator

Answer 70

none of these.

Question 71

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

Answer 71

1

Question 72

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

Answer 72

A vapor phase reactor.

Question 73

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

Answer 73

density of the gas and inversely as viscosity of the gas

Question 74

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

Answer 74

all multipass

Question 75

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

Answer 75

decreases upwards.

Question 76

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.

Answer 76

damaging

Question 77

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

Answer 77

3 to 12.5

Question 78

Factor of safety (i.e., overdesign factor) in heat transfer equipments is about __________ percent more than the actual/theoretical design factor.

Answer 78

15-20

Question 79

In actual operation of distillation column, the vapour is not distributed uniformly among the bubble caps, primarily because of the

Answer 79

liquid gradient on the tray

Question 80

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

Answer 80

D/5 or minimum 2" to 5D.

Question 81

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

Answer 81

remains same

Question 82

In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement

Answer 82

results in higher shell side pressure drop

Question 83

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.

Answer 83

(1/n)th

Question 84

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

Answer 84

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

Question 85

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

Answer 85

high latent heat.

Question 86

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

Answer 86

Conical

Question 87

Pick out the wrong statement pertaining to 'Horton sphere' used for the storage of liquid ammonia.

Answer 87

Horton sphere is used for the storage of liquid at sub-zero temperature at very high pressure upto 200 kg/cm2 .

Question 88

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

Answer 88

1.25-1.50 times

Question 89

Accidents in chemical plants are mostly due to

Answer 89

faulty operating procedures

Question 90

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

Answer 90

bubble cap

Question 91

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

Answer 91

Permissible slot velocity

Question 92

Pick out the wrong statement about distillation operation

Answer 92

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

Question 93

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

Answer 93

Copper

Question 94

In a shell and tube heat exchanger, the clearance of the tube is generally

Answer 94

not less than one-fourth of the tube diameter or 3/16".

Question 95

Diameter of the seive tray column is determined by the

Answer 95

upper limit of the vapour velocity

Question 96

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

Answer 96

decreases.

Question 97

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

Answer 97

12.5

Question 98

Bubble cap tray is the most commonly used tray in large distillation column, because

Answer 98

of its flexibility and nearly constant efficiency under varying conditions of operation.