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

Le/D for fully open globe value may be around

Answer 6

300

Question 7

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

Answer 7

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

Question 8

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

Answer 8

increases

Question 9

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

Answer 9

2.5 to 5

Question 10

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 10

5-11

Question 11

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

Answer 11

elastic limit

Question 12

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

Answer 12

shortest center to center distance between adjacent tubes.

Question 13

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 13

Reflux is not a saturated liquid.

Question 14

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)

Answer 14

η = 17 - 61.1 log μ

Question 15

In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about __________ cms.

Answer 15

10

Question 16

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.

Answer 16

8

Question 17

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 17

(1.2)^5/3

Question 18

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

Answer 18

At the inner surface.

Question 19

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

Answer 19

0.80

Question 20

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

Answer 20

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

Question 21

Bracket supports are the most suitable for supporting __________ vessels.

Answer 21

thick walled vertical

Question 22

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

Answer 22

inside diameter

Question 23

Steam side heat transfer co-efficient for design consideration under ordinary condition can be assumed to be about __________ kcal/hr.m2.°C.

Answer 23

7500

Question 24

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 24

20

Question 25

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

Answer 25

60°

Question 26

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 26

75

Question 27

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 27

less

Question 28

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 28

20-40

Question 29

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

Answer 29

ultimate stress to working stress.

Question 30

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

Answer 30

1

Question 31

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

Answer 31

Cross flow

Question 32

The main purpose of providing stepping on the trays is to

Answer 32

facilitate handling of large flow rate of liquid.

Question 33

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

Answer 33

50-150

Question 34

The ends of a cylindrical 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 34

Ellipsoidal

Question 35

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

Answer 35

Di, opt = 3 Q^0.36 ρ^0.18

Question 36

Pick out the correct statement.

Answer 36

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

Question 37

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

Answer 37

LESS

Question 38

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

Answer 38

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

Question 39

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

Answer 39

0.1 to 2

Question 40

A stuffing box is used for

Answer 40

prevention of fluid leakage around moving parts.

Question 41

Pressure drop (Δp) and the superficial gas mass velocity (G) in case of packed absorption tower operating in the preloading range are related as

Answer 41

Δp = G2

Question 42

Pick out the wrong statement.

Answer 42

dished bottom vessel has very high power consumption.

Question 43

Pick out the wrong statement.

Answer 43

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

Question 44

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 44

decreases

Question 45

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 45

central dished section and corner torus section.

Question 46

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

Answer 46

Allowable vapor velocity.

Question 47

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 47

smaller reactor should come first.

Question 48

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?

Answer 48

Sorel-Lewis method.

Question 49

Saddle supports are used for supporting __________ vessels.

Answer 49

horizontal cylindrical

Question 50

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.

Answer 50

15 to 30

Question 51

In packed towers provided with saddle packing, liquid redistributors are positioned at every __________ times column diameter or 6 meters whichever is less.

Answer 51

5-8

Question 52

Optimum reflux ratio in a continuous distillation column is determined by the

Answer 52

total cost consideration (fixed cost of the column plus the cooling water & steam cost).

Question 53

Cooling water fouling factors vary in the range of 0.001 to 0.003

Answer 53

(BTU/hr.ft2 . °F)-1

Question 54

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

Answer 54

0.2 D

Question 55

The maximum liquid gradient over a tray must not exceed

Answer 55

0.5” -1.25”.

Question 56

An under designed steam trap will

Answer 56

back up condensate and cause water hammer in steam line.

Question 57

Speed of industrial paddle agitator ranges from __________ rpm.

Answer 57

20-100

Question 58

__________ strain is measured using a ‘strain rosetter’.

Answer 58

Linear

Question 59

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

Answer 59

fixed charges initially

Question 60

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

Answer 60

∞

Question 61

Vertical vessels are not supported by

Answer 61

saddles

Question 62

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

Answer 62

withstand higher pressure for a given metallic shell thickness.

Question 63

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

Answer 63

allow for thermal expansion and facilitate installation.

Question 64

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

Answer 64

Minimum recommended down comer residence time for the disengagement of entrained vapour is the same for both foaming and non-foaming liquids, which is about 20 seconds.

Question 65

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

Answer 65

30

Question 66

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.

Answer 66

0.1 to 0.25

Question 67

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

Answer 67

chain

Question 68

Pick out the wrong statement:

Answer 68

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

Question 69

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

Answer 69

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 70

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

Answer 70

pd/2t

Question 71

LMTD correction factor is used in heat exchanger design for

Answer 71

multipass shell and tube heat exchanger.

Question 72

Floating head heat exchangers are used for the

Answer 72

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

Question 73

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

Answer 73

6” dia cap with 4” dia riser.

Question 74

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 74

nozzle or rim

Question 75

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

Answer 75

8

Question 76

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 76

1.25 to 3.125

Question 77

Rivets are generally specified by the

Answer 77

shank diameter

Question 78

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

Answer 78

4 to 10

Question 79

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 79

19

Question 80

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 viscosity above __________ poise

Answer 80

600

Question 81

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 81

1

Question 82

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

Answer 82

A vapor phase reactor.

Question 83

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

Answer 83

all multipass

Question 84

For a cylindrical shell, (subject to the thickness of uppermost course being more than the minimum for diameter of the tank in question), the thickness of the courses of shell

Answer 84

decreases upwards.

Question 85

In the design of a paddle agitator, the ratio paddle dia / tank dia is normally taken as

Answer 85

0.8

Question 86

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 86

Damaging

Question 87

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

Answer 87

3 to 12.5

Question 88

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

Answer 88

15-20

Question 89

For annular flow of a fluid, the ratio of the equivalent diameter for pressure drop calculation to the equivalent diameter for heat transfer calculation is

Answer 89

d1 / d1 + d2

Question 89

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

Answer 89

liquid gradient on the tray

Question 90

The minimum shell thickness for tank ≤ 15 metres diameter is limited to __________ mm, for reasons of elastic stability.

Answer 90

5

Question 91

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 91

D/5 or minimum 2” to 5D.

Question 92

Brass valves are usually made for pipe sizes __________ inches.

Answer 92

≤ 2

Question 93

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

Answer 93

results in higher shell side pressure drop.

Question 94

Pick out the wrong statement about routing of fluids in a shell and tube heat exchanger.

Answer 94

Higher pressure fluid stream should be routed through the shell side.

Question 95

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 95

(1/n)th

Question 96

Pick out the wrong statement

Answer 96

Flat head covers are most suitable for larger vessels operating at very high pressure.

Question 97

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

Answer 97

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

Question 98

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

Answer 98

high latent heat.

Question 98

__________ shaped roof is the most commonly used roof for cylindrical storage tanks.

Answer 98

Conical

Question 99

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

Answer 99

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

Question 100

Value of Peclet number = ∞, is the representative of

Answer 100

plug flow.

Question 100

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

Answer 100

1.25-1.50 times

Question 101

In a distillation column, bubble caps are located on trays with a pitch of __________ times the outside diameter of the caps.

Answer 101

1.3 to 2

Question 102

A perforated plate has holes of diameter dn arranged in a pitch ph. Each hole has a tube of I.D. dt passing through it. The ligament efficiency is given by

Answer 102

(ph - dt)/ph

Question 103

Accidents in chemical plants are mostly due to

Answer 103

faulty operating procedures.

Question 104

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

Answer 104

bubble cap

Question 105

Pick out the wrong statement about distillation operation

Answer 105

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

Question 106

Normal screwed fittings are used for pipes upto a diameter of __________ inches.

Answer 106

3

Question 107

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

Answer 107

Copper

Question 107

Low pressure steam (with saturation temperature between 105 to 120°C) is usually used in the vacuum evaporators, which normally employ a vacuum of about __________ mm Hg (referred to a 760 mm mercury barometer).

Answer 107

650

Question 108

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

Answer 108

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

Question 109

High pressure fluid in a shell and tube heat exchanger should preferably be routed through the

Answer 109

tubes to avoid the expansion of high pressure shell construction.

Question 110

In case of a ‘thin’ pressure vessel, the ratio of its diameter to wall thickness is

Answer 110

> 10

Question 111

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

Answer 111

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

Question 112

Diameter of the sieve tray column is determined by the

Answer 112

upper limit of the vapour velocity.

Question 112

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

Answer 112

12.5

Question 113

In common bubble cap distillation column design practice, riser area is approximately equal to (where, Aa = Annular passage area, and Sa = Slot area)

Answer 113

Aa = Sa

Question 114

Heat transfer co-efficient, hG(Kcal/hr.m2 .°C) and mass velocity of air, G (kg/hr.m2 ) for air flow parallel to the surface in case of constant drying rate in batch drying is related as hG = 0.0176G0.8. But when the flow of air perpendicular to the surface is encountered, this equation changes to

Answer 114

hG = 1.004G0.37

Question 115

In the agitators, the power required will be changed with the increase of diameter of agitator (D) as

Answer 115

D^5

Question 116

Apex angle of conical heads used in the bottom heads of chemical process equipment’s is usually

Answer 116

60

Question 117

Circumferential (hoop) stress in a thin cylindrical vessel under internal pressure is __________ the longitudinal stress.

Answer 117

twice

Question 118

For storing hazardous chemicals in large storage tanks, the minimum safe distance between the two tanks should range between __________ times the tank diameter.

Answer 118

1 to 1.5

Question 119

The absorption factor is defined as (where, S1 = slope of the equilibrium curve, S2 = slope of the operating line)

Answer 119

S1/S2

Question 120

In a cylinderical vessel subjected to internal pressure, the longitudinal stress σL and the circumferential stress, σn are related by

Answer 120

σh = 2 σL

Question 121

Nominal size of a pipe is an indication of its __________ diameter.

Answer 121

approximate

Question 122

__________ shaped roof is most commonly used for cylindrical tanks.

Answer 122

cone

Question 123

In a thin cylindrical shell, the hoop stress is __________ stress.

Answer 123

circumferential tensile

Question 124

Commercial packed scrubbers are normally designed for a pressure drop range of __________ mm water coloumn per metre of packed height.

Answer 124

17-34

Question 125

Rotary driers are most economically designed for the number of heat transfer units (HTU) from

Answer 125

1.5 to 2.5

Question 126

The difficulty of liquid distribution in packed towers is accentuated, when the ratio of tower diameter to packing diameter is

Answer 126

< 7

Question 127

With increase in temperature drop (in a shell and tube heat exchanger), the LMTD correction factor, FT

Answer 127

decreases very rapidly

Question 128

The normal range of velocity of steam in pipes is __________ m/sec.

Answer 128

80-100

Question 129

__________ dished head is the strongest of all.

Answer 129

Hemispherical

Question 130

“A claming section” before the liquid flows into the down comer is provided to

Answer 130

permit release of entrained vapour in the liquid

Question 131

The units of Young’s modulus of elasticity and __________ are the same.

Answer 131

stress

Question 132

Vertical condenser is advantageous to the horizontal condenser from operation point of view, when

Answer 132

both the functions of condensation & sub cooling are carried out in a single unit.

Question 133

Hazards associated with the relief valve leakage for extremely hazardous material storage can be taken care of by providing

Answer 133

rupture diaphragm

Question 134

Minimum baffle spacing recommended in a shell and tube heat exchanger is equal to

Answer 134

5 cms

Question 135

__________ liquor is best handled in a long tube vertical evaporator.

Answer 135

Foamy

Question 136

Theoretically calculated diameter of the stripping section of the continuous rectification column is __________ that of the enriching section.

Answer 136

more than

Question 137

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

Answer 137

negative

Question 138

The testing pressure of storage tanks and pressure vessels designed as per Indian standard codes should be about __________ times. the design pressure.

Answer 138

1.5 to 2

Question 139

The ratio of down take area to cross-sectional area of the tube, for calendria type evaporator ranges from

Answer 139

0.5 to 1

Question 140

Shortest distance between two tubes is

Answer 140

called tube clearance.

Question 141

__________ tower is the most suitable gas-liquid contacting device involving highly corrosive fluids.

Answer 141

Packed

Question 142

At equal mass velocities, the values of film co-efficient for gases as compared to that for liquids are generally.

Answer 142

lower

Question 143

The ratio of the largest load in a test to the original cross-sectional area of the test specimen is called the __________ stress.

Answer 143

ultimate

Question 144

A ‘rupture disc’ is provided in chemical equipment as an accessory meant for

Answer 144

relieving excess pressure

Question 145

In a shell and tube heat exchanger, the shortest centre to centre distance between the adjacent tubes is

Answer 145

called tube pitch.

Question 146

Minimum tube pitch recommended for shell and tube heat exchangers is about __________ times the outside diameter of the tube.

Answer 146

1.25

Question 146

Any shell opening greater than 5 cms for a storage tank must be reinforced for reason of

Answer 146

preventing the local overstressing of the shell around the opening.

Question 147

Slope of countercurrent flow rotary drier is in the range of __________ meter/metre.

Answer 147

0 to 0.08

Question 147

Liquid redistribution should be done in a packed tower packed with raschig rings every 6 metres or __________ times the column diameter, whichever is lower.

Answer 147

2.5-3.0

Question 148

In case of saddle packing (e.g., berl and intralox saddles), the maximum size of the packing should not exceed __________ of the column diameter.

Answer 148

l/15th

Question 149

The thermal stress in a metallic bar does not depend upon the

Answer 149

cross-sectional area.

Question 150

For turbulent flow (NRe > 2100) of low viscosity fluid (μ > 20cp) in steel pipes, the optimum inside pipe diameter is given by(where, Q = fluid flow rate, ft3/sec.ρ = fluid density, lb/ft3 μ = fluid viscosity, centipoise Di = optimum inside pipe diameter, inches)

Answer 150

Di, opt = 3.9 Q0.45 ρ0.13

Question 150

To avoid the tearing off the plate of an edge, the margin (i.e., the minimum distance from the centre of the rivet hole to the nearest edge of the plate) should be equal to

Answer 150

1.5 d

Question 151

The normal range of velocity of water in pipes is __________ m/sec.

Answer 151

1-2

Question 152

Baffles are provided in a shell and tube heat exchanger to increase the turbulence and velocity of the shell side fluid. Which of the following shaped baffles does not fall in the category of transverse baffle ?

Answer 152

Flat plate extending across the wall

Question 153

A certain pressure vessel manufacturer avoids doing reinforcements calculations for openings by always providing a reinforcing pad extending upto double the diameter of the opening and of the same material and thickness as that of the shell wall. If area compensation is accepted as a code guideline, his approach leads to safe design

Answer 153

irrespective of the shape of the vessel.

Question 153

In a __________ rivetted joint, the number of rivets decreases from the inner most row to the outer most row.

Answer 153

diamond

Question 153

Large process vessels operating under extreme temperature and pressure conditions are normally clad/ lined with materials like stainless steel, aluminum, nickel & its alloys, copper & its alloys and titanium. The cladding thickness is generally about __________ percent of the total thickness.

Answer 153

10 to 20

Question 154

The buckling tendency of compression members is always in the direction of the

Answer 154

least radius of gyration.

Question 155

In case of plain carbon steel, butt welded joints are used for shell plate thickness ≤ __________ cms.

Answer 155

3.8

Question 156

The average velocity in the tubes of a 1-4 heat exchanger is __________ times that in 1-1 heat exchanger having the same size & number of tubes and operated at same liquid flow rate.

Answer 156

4

Question 156

Hoop (circumferential) stress induced in a thin walled ‘Horton Sphere’ used for the storage of liquid ammonia under pressure is

Answer 156

pD / 2t

Question 157

When one of the fluids is highly corrosive and has fouling tendency, it should

Answer 157

preferably flow inside the tube for its easier internal cleaning.

Question 157

The LMTD correction factor (FT) is defined as the

Answer 157

ratio of true temperature difference to the LMTD.

Question 158

The clearance between two tubes in a shell and tube heat exchanger is known as ‘ligament’, whose minimum value is __________ the outside diameter of the tube, but in no case it should be less than 4.5 mm.

Answer 158

one fourth

Question 158

Value of Peclet number = 0, is the representative of

Answer 158

complete back mixing.

Question 159

Poisson’s ratio of a material is the ratio of unit lateral strain to the unit axial elongation within its elastic limit. The value of Poisson’s ratio for structural and pressure vessel steel may be taken as

Answer 159

0.3

Question 160

Removable connection of tubes to tube sheet is called

Answer 160

ferrule

Question 160

Typical static submergence for bubble cap plate column operating at atmospheric pressure may be around

Answer 160

0.5”

Question 161

What is the slope of the operating line in the rectifying section of a distillation coloumn ?

Answer 161

<1

Question 161

Back-trapping in a distillation column results due to

Answer 161

excessive liquid gradient over the tray.

Question 162

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

Answer 162

18

Question 163

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 ?

Answer 163

0.8

Question 163

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

Answer 163

15

Question 164

A/an __________ is used for changing the direction of a pipeline.

Answer 164

elbow

Question 164

Maximum plate efficiency is achieved in case of __________ flow.

Answer 164

cross

Question 165

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

Answer 165

if its diameter is less than 15-20metres.

Question 165

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

Answer 165

flanged

Question 166

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

Answer 166

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

Question 167

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

Answer 167

large diameter tanks

Question 167

large diameter tanks

Answer 167

ellipsoidal (2 : 1)

Question 168

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

Answer 168

it reduces heat transfer area.

Question 168

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.

Answer 168

1/10-1/15th

Question 169

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

Answer 169

entrainment considerations.

Question 170

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

Answer 170

less

Question 171

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

Answer 171

0.4-0.9

Question 172

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.

Answer 172

thermal

Question 172

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

Answer 172

Smaller dia vessel.

Question 172

Reflux ratio variation in a distillation column is between

Answer 172

minimum and infinity

Question 173

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

Answer 173

25

Question 173

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

Answer 173

Disk and doughnut baffle is the most commonly used baffle.

Question 174

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

Answer 174

blue

Question 175

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

Answer 175

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

Question 176

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

Answer 176

floating

Question 177

Pick out the wrong statement.

Answer 177

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

Question 177

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

Answer 177

thrice

Question 178

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

Answer 178

positive

Question 179

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 179

increase by 21.

Question 179

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

Answer 179

creating turbulence.

Question 180

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

Answer 180

25% cut segmental baffle.

Question 181

Safety valves are provided in chemical equipment to guard against excessive

Answer 181

pressure/pressure fluctuation

Question 182

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

Answer 182

not related with

Question 183

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 183

static submergence

Question 184

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 184

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

Question 185

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 185

80

Question 185

A cylindrical pressure vessel of volume 6 πm3 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 185

10 mm

Question 186

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

Answer 186

Cross-partition rings.

Question 186

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

Answer 186

High specific heat

Question 187

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

Answer 187

containing suspended solids flows at low velocity.

Question 188

Lug support is meant for supporting __________ vessels.

Answer 188

small

Question 189

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

Answer 189

Triangular pitch.

Question 190

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

Answer 190

saddle

Question 191

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

Answer 191

0.07 - 0.12

Question 192

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

Answer 192

0.85

Question 192

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 192

considerably more than 9

Question 192

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

Answer 192

twice

Question 193

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

Answer 193

modulus of elasticity

Question 194

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

Answer 194

Ellipsoidal

Question 195

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

Answer 195

100

Question 196

Optimum economic pipe diameter for fluid flow is determined by the

Answer 196

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

Question 197

Vertical storage vessels are never supported by __________ support.

Answer 197

saddle

Question 198

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

Answer 198

more than that for fluid flow.

Question 199

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 199

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

Question 200

__________ heat exchanger is also known as ‘hair pin type’ exchanger,

Answer 200

Double pipe

Question 201

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

Answer 201

1.5

Question 202

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

Answer 202

Poisson’s ratio

Question 203

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

Answer 203

margin

Question 204

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

Answer 204

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

Question 205

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

Answer 205

short (< 2 m) and housed indoor.

Question 206

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 206

> 1

Question 207

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 207

equal to

Question 207

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 207

bending

Question 207

__________ closure is the weakest enclosure for cylindrical vessels.

Answer 207

Conical or flat plate

Question 208

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

Answer 208

Murphree plate efficiency.

Question 209

Scale up problem in design based on the similarity concept takes into account __________ similarity.

Answer 209

dynamic, geometrical, kinematic

Question 210

le/D for fully open globe value may be around

Answer 210

300

Question 211

Lug support is

Answer 211

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

Question 212

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

Answer 212

increases

Question 213

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

Answer 213

2.5 to 5.

Question 214

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 214

5-11

Question 215

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

Answer 215

elastic limit

Question 216

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

Answer 216

shortest centre to centre distance between adjacent tubes

Question 217

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 217

Reflux is not a saturated liquid.

Question 218

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)

Answer 218

η = 17 - 61.1 log μ

Question 219

The value of fouling factor depends upon the

Answer 219

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

Question 219

In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about __________ cms.

Answer 219

10

Question 219

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.

Answer 219

8

Question 220

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 220

(1.2)^5/3

Question 221

In a heat exchanger, shell side fluid velocity can be changed by changing the tube

Answer 221

both (a) & (b)

Question 221

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

Answer 221

At the inner surface.

Question 222

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

Answer 222

0.80

Question 223

A rivetted joint does not fail by __________ of rivets.

Answer 223

none of these

Question 223

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

Answer 223

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

Question 223

Bracket supports are the most suitable for supporting __________ vessels.

Answer 223

thick walled vertical

Question 224

In a multipass shell and tube heat exchanger, the shell side cross flow area does not depend upon

Answer 224

none of these

Question 225

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

Answer 225

inside diameter

Question 226

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 226

20

Question 227

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.

Answer 227

none of these.

Question 228

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

Answer 228

dished bottom vessel has very high power consumption.

Question 228

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

Answer 228

0.1 to 2

Question 229

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

Answer 229

all a, b & c.

Question 230

Needle valves are generally not used for

Answer 230

very large diameter pipes.

Question 231

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 231

decreases

Question 232

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 232

central dished section and corner torus section.

Question 233

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

Answer 233

Allowable vapour velocity.

Question 234

In case of a continuous distillation column, increase in reflux ratio may result in the

Answer 234

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

Question 235

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

Answer 235

-q/(1-q)

Question 235

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 235

smaller reactor should come first.

Question 236

Pick out the wrong statement:

Answer 236

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

Question 237

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 237

remains same

Question 238

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

Answer 238

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

Question 238

Pick out the wrong statement

Answer 238

Flat head covers are most suitable for larger vessels operating at very high pressure.

Question 239

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

Answer 239

results in higher shell side pressure drop.

Question 240

Pick out the wrong statement about routing of fluids in a shell and tube heat exchanger.

Answer 240

Higher pressure fluid stream should be routed through the shell side.

Question 240

In shell and tube heat exchangers, straight tie rods are used to

Answer 240

hold baffle in space.

Question 241

Tube side heat transfer co-efficient for turbulent flow of liquid through tubes is proportional to

Answer 241

G0.8

Question 241

An increase in the liquid resistance to interphase mass transfer and a resultant reduction in plate efficiency is caused by

Answer 241

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

Question 242

What is the slope of the operating line in the stripping section of a distillation column ?

Answer 242

> 1

Question 242

For storing hazardous chemicals in large storage tanks, the minimum safe distance between the two tanks should range between __________ times the tank diameter.

Answer 242

1 to 1.5

Question 243

What is the slope of the operating line in the rectifying section of a distillation column ?

Answer 243

<1

Question 244

Joint efficiency (J) for a seamless pipe is

Answer 244

1

Question 244

Heat transfer co-efficient for a horizontal condenser as compared to a vertical condenser operating under similar conditions is

Answer 244

about 3 times

Question 245

Back-trapping in a distillation column results due to

Answer 245

excessive liquid gradient over the tray.

Question 246

Liquid gradient over a tray can be minimized by

Answer 246

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

Question 247

In perforated plate towers, the

Answer 247

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

Question 247

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 247

Ellipsoidal

Question 248

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

Answer 248

Di, opt = 3 Q0.36 ρ0.18

Question 249

Pick out the correct statement.

Answer 249

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

Question 249

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

Answer 249

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

Question 250

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.

Answer 250

none of these.

Question 251

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

Answer 251

0.1 to 2

Question 251

Pressure drop (Δp) and the superficial gas mass velocity (G) in case of packed absorption tower operating in the preloading range are related as

Answer 251

Δp = G2