Process Equipment and Plant Design

Question 1

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

Answer 1

2

Question 2

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

Answer 2

23

Question 3

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

Answer 3

250-500

Question 4

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 4

two

Question 5

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

Answer 5

25 and 60

Question 6

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

Answer 6

1.5

Question 7

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

Answer 7

0.25 to 8

Question 8

Cylinderical shell thickness of rotary drier is generally __________ mm.

Answer 8

6-8

Question 9

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

Answer 9

margin

Question 10

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

Answer 10

38

Question 11

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

Answer 11

Wrongggg

Question 12

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 12

> 1

Question 13

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

Answer 13

60

Question 14

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 14

equal to

Question 15

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 15

bending

Question 16

__________ closure is the weakest enclosure for cylindrical vessels.

Answer 16

Conical or flat plate

Question 17

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

Answer 17

floating

Question 18

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

Answer 18

Wrongggg

Question 19

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

Answer 19

5

Question 20

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

Answer 20

thrice

Question 21

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

Answer 21

d=1.6√T

Question 22

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

Answer 22

positive

Question 23

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

Answer 23

Horizontal tube evaporator

Question 24

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 24

2^0.8

Question 25

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

Answer 25

creating turbulence

Question 26

For turbine agitator, the impeller diameter is about

Answer 26

0.3 to 0.5d

Question 27

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 27

increase by 2^1.6

Question 28

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

Answer 28

25% cut segmental baffle.

Question 29

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

Answer 29

6.5 mm

Question 30

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

Answer 30

Correctuee

Question 31

Safety valves are provided in chemical equipments to guard against excessive

Answer 31

pressure/pressure fluctuation

Question 32

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

Answer 32

smaller than

Question 33

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 33

80

Question 34

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

Answer 34

d

Question 35

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

Answer 35

0.1-0.12

Question 36

A cylinderical pressure vessel of volume 6 πm3has to be designed to withstand a maximum internal pressure of 10 atm. The allowable design stress of the material is 125N/mm2and corrosion allowance is 2 mm. The thickness of the vessel for a length/diameter ratio of 3 will be close to

Answer 36

10 mm

Question 37

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 37

4 A/P

Question 38

Lug support is meant for supporting __________ vessels.

Answer 38

small

Question 39

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

Answer 39

decreases

Question 40

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

Answer 40

saddle

Question 41

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

Answer 41

0.07-0.12

Question 42

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

Answer 42

0.85

Question 43

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

Answer 43

twice

Question 44

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 44

1

Question 45

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 45

considerably more than 9

Question 46

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 46

2.5 to 4.0

Question 47

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’.

Answer 47

wronggggggg

Question 48

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

Answer 48

100

Question 49

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

Answer 49

increases

Question 50

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

Answer 50

2.5 to 5

Question 51

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 51

5-11

Question 52

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

Answer 52

10

Question 53

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 53

8

Question 54

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 54

(1.2)^5/3

Question 55

It is not desirable to design a heat exchanger forLMTDcorrection factor,FT, of less than

Answer 55

0.80

Question 56

Bracket supports are the most suitable for supporting __________ vessels.

Answer 56

thick walled vertical

Question 57

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

Answer 57

inside diameter

Question 58

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

Answer 58

7500

Question 59

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 59

20

Question 60

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

Answer 60

60°

Question 61

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 61

75

Question 62

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 62

less

Question 63

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 63

20-40

Question 64

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

Answer 64

Cross flow

Question 65

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

Answer 65

50-150

Question 66

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

Answer 66

Correctueer

Question 67

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

Answer 67

less

Question 68

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

Answer 68

Wrong

Question 69

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

Answer 69

0.1 to 2

Question 70

dished bottom vessel has very high power consumption.

Answer 70

Wrongggg

Question 71

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

Answer 71

2.5 - 5 (second lower)

Question 72

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 72

5-11 (second lower)

Question 73

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

Answer 73

10

Question 74

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 74

8

Question 75

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 75

(1.2)^5/3

Question 76

It is not desirable to design a heat exchanger forLMTDcorrection factor,FT, of less than

Answer 76

0.80

Question 77

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

Answer 77

7500

Question 78

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 78

20

Question 79

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

Answer 79

60°

Question 80

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 80

75

Question 81

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 81

less

Question 82

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 82

20-40 (second lowest)

Question 83

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

Answer 83

Cross flow

Question 84

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

Answer 84

50-150 (second lowest)

Question 85

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 85

decreases

Question 86

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 86

15-30

Question 87

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

Answer 87

5-8

Question 88

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

Answer 88

0.2D

Question 89

The maximum liquid gradient over a tray must not exceed

Answer 89

0.5” - 1.25”

Question 90

Speed of industrial paddle agitator ranges from __________ rpm.

Answer 90

20-100 (second lowest)

Question 91

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

Answer 91

increase

Question 92

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

Answer 92

30

Question 93

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 93

0.1 to 0.25

Question 94

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

Answer 94

8

Question 95

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 95

1.25 to 3.125 (second lower)

Question 96

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

Answer 96

4 to 10 (second lower)

Question 97

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 97

19 (second lower)

Question 98

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 98

600 (second lower)

Question 99

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 99

1

Question 100

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 100

decreases upwards

Question 101

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

Answer 101

0.8 (second lower)

Question 102

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 102

damaging

Question 103

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

Answer 103

3 to 1.25

Question 104

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

Answer 104

15-20 (second lower)

Question 105

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

Answer 105

5

Question 106

Brass valves are usually made for pipe sizes __________ inches.

Answer 106

≤2 (second lower)

Question 107

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 107

remains same

Question 108

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

Answer 108

1.25-1.50 times

Question 109

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

Answer 109

1.3 to 2

Question 110

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 110

650

Question 111

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

Answer 111

3

Question 112

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

Answer 112

12.5

Question 113

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

Answer 113

> 10

Question 114

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

Answer 114

D^5

Question 115

Apex angle of conical heads used in the bottom heads of chemical process equipments is usually

Answer 115

60°

Question 116

A pressure vessel is said to be made of ‘thick’ shell, if the ratio of its diameter to wall thickness is

Answer 116

10

Question 117

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

Answer 117

G^0.8

Question 118

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

Answer 118

twice

Question 119

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

Answer 119

1 to 1.5

Question 120

The ratio of tube length to shell diameter in case of liquid shell and tube heat exchanger ranges from

Answer 120

4 to 8

Question 121

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

Answer 121

> 1

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

In actual operation of a bubble cap distillation tower, the __________ at the bottom of the tower is more than that at the top of the tower.

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

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

Answer 130

5 cms

Question 131

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

Answer 131

more than

Question 132

Hold up of material in a operating rotary drier is in the range of

Answer 132

0.05 to 0.15

Question 133

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

Answer 133

1.5 to 2

Question 134

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

Answer 134

0.5 to 1

Question 135

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

Answer 135

Packed

Question 136

The wall thickness of thin cylindrical shell with hemispherical ends is __________ that of the spherical ends.

Answer 136

more than

Question 137

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

Answer 137

1.25

Question 138

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 138

2.5-3.0

Question 139

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

Answer 139

0 to 0.8

Question 140

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 140

l/15th

Question 141

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 141

1.5 d

Question 142

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

Answer 142

1-2

Question 143

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

Answer 143

10 to 20 (second lowest)

Question 144

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

Answer 144

about 3 times

Question 145

The longitudinal stress induced in a thin walled cylinderical vessel under internal pressure is

Answer 145

pd/4t

Question 146

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

Answer 146

3.8

Question 147

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 147

4

Question 148

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

Answer 148

pD/2t

Question 149

The ratio, propeller agitator dia/tank dia is normally taken as

Answer 149

0.15-0.30

Question 150

Maximum plate efficiency is achieved in case of __________ flow.

Answer 150

cross

Question 151

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 151

one fourth

Question 152

The ratio for the rate of washing to the final rate of filtration in a washing type of plate and frame filter is

Answer 152

0.25

Question 153

Normally, the length to diameter ratio of rotary dryers varies form 4 to 10 and for its economic operation, the number of transfer units (NTU) for such dryers varies from

Answer 153

1.5-2.5

Question 154

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 154

0.3

Question 155

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

Answer 155

0.5”

Question 156

The length of straight rectangular weir used on cross-flow trays is generally __________ the column diameter.

Answer 156

0.6-0.8 times

Question 157

Le/D for couplings and unions would be

Answer 157

negligible

Question 158

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

Answer 158

<1

Question 159

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

Answer 159

18

Question 160

Joint efficiency (J) for a seamless pipe is

Answer 160

1

Question 161

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

Answer 161

orifice

Question 162

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 162

0.8

Question 163

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

Answer 163

more

Question 164

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

Answer 164

15

Question 165

Lap joints are preferred for plates having thickness __________ mm.

Answer 165

> 3

Question 166

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

Answer 166

7.5 (second lowest)

Question 167

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

Answer 167

10 metres

Question 168

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

Answer 168

10000

Question 169

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

Answer 169

d

Question 170

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

Answer 170

flanged

Question 172

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

Answer 172

45 deg

Question 173

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

Answer 173

1.1 to 1.5

Question 174

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

Answer 174

increases

Question 175

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

Answer 175

50-75

Question 176

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

Answer 176

1/D^5

Question 177

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

Answer 177

6

Question 178

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

Answer 178

0.1-0.2

Question 179

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

Answer 179

1/30th

Question 180

Longitundinal stress induced in a thin walled cylindrical storage vessel is

Answer 180

pD/4t

Question 181

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 181

thermal

Question 182

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

Answer 182

25

Question 183

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

Answer 183

less

Question 184

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

Answer 184

0.4-0.9

Question 185

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

Answer 185

Smaller dia vessel

Question 186

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

Answer 186

1/8 and 1/64

Question 187

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 187

1/10-1/15th

Question 188

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

Answer 188

0.08 to 0.12 d

Question 189

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

Answer 189

0.6 to 0.7 (second lowest)