Process Equipment and Plant Design Flashcards
1
Q
Liquid/petroleum fuel storage tanks are built underground (as in case of petrol pumps), when the storage capacity is less than __________ kilolitres.
45
A
45
2
Q
Le/D for fully open globe value may be around
300
A
300
3
Q
Holes of a sieve tray are arranged in triangular pitch of __________ times the hole diameter.
2.5 to 5
A
2.5 to 5
4
Q
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.
5-11
A
5-11
5
Q
In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about __________ cms.
10
A
10
6
Q
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.
8
A
8
7
Q
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
(1.2)^5/3
A
(1.2)^5/3
8
Q
It is not desirable to design a heat exchanger for LMTD correction factor, FT, of less than
0.80
A
0.80
9
Q
Two iron pipes of the same nominal diameter but different schedule numbers will have the same
inside diameter
A
inside diameter
10
Q
Steam side heat transfer co-efficient for design consideration under ordinary condition can be assumed to be about __________ kcal/hr.m2.°C.
7500
A
7500
11
Q
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.
20
A
20
12
Q
In chemical process equipments, the conical bottom heads used, usually has an apex angle of
60°
A
60°
13
Q
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.
75
A
75
14
Q
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.
20-40
A
20-40
15
Q
What is the value of ‘q’ for saturated liquid feed to a distillation column ?
1
A
1
16
Q
The operating pressure drop range in a bag filter is about __________ mm water gauge.
50-150
A
50-150
17
Q
Speed of the drum of the rotary vacuum filter normally ranges from __________ rpm.
0.1 to 2
A
0.1 to 2
18
Q
Pressure drop (Δp) and the superficial gas mass velocity (G) in case of packed absorption tower operating in the preloading range are related as
Δp = G^2
A
Δp = G^2
19
Q
With increase in gas flow rate to fabric surface area ratio (Nm3/hr/m2 fabric surface area), the size & the cost of a bag filter
decreases
A
decreases
20
Q
The diameter of a propeller agitator used in agitation tank ranges from __________ percent of the tank diameter and its peripherial speed is normally 300 to 500 metres/minute.
15 to 30
A
15 to 30
21
Q
In packed towers provided with saddle packing, liquid redistributors are positioned at every __________ times column diameter or 6 metres whichever is less.
5-8
A
5-8
22
Q
Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter )
0.2 D
A
0.2 D
23
Q
The maximum liquid gradient over a tray must not exceed
0.5” -1.25”.
A
0.5” -1.25”.
24
Q
The slope of the feed line in distillation opeartion is given by (where, q = fraction of the feed stream that is liquid.)
-q/(1-q)
A
-q/(1-q)
25
Speed of industrial paddle agitator ranges from __________ rpm.
20 to 100
20 to 100
26
Thin spherical shells subjected to internal pressure, develop __________ stresses.
radial
radial
27
The slope of operating line in the rectifying section of a distillation column is unity, if the reflux ratio is
∞
∞
28
With increase in pressure drop (for a given particle size), the dust collection efficiency of a cyclone separator will
increase
increase
29
Overall tray efficiency of a distillation column is the ratio of the number of
ideal trays required to the number of real trays required.
ideal trays required to the number of real trays required.
30
Generally, no corrosion allowance in wall thickness of a part is required, if the thickness is more than __________ mm.
30
30
31
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.
0.1 to 0.25
0.1 to 0.25
32
The circumferential (hoop) stress in a thin walled cylinderical vessel under internal pressure is
pd/2t
pd/2t
33
LMTD correction factor is used in heat exchanger design for
multipass shell and tube heat exchanger.
multipass shell and tube heat exchanger.
34
The most common standard size of bubble caps used in industrial operation is
6" dia cap with 4" dia riser.
6" dia cap with 4" dia riser.
35
In a distillation column, the minimum residence time for liquid in the downspout is about __________ seconds.
8
8
36
Thickness of the frame of a plate and frame filter as compared to that of plates is
more
more
37
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.
1.25 to 3.125
1.25 to 3.125
38
Length to diameter ratio of most rotary driers is in the range of
4 to 10
4 to 10
39
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.
19
19
40
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.
600
600
41
The dust collection efficiency of a cyclone separator
none of these.
none of these.
42
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
1
1
43
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
decreases upwards.
decreases upwards.
44
In the design of a paddle agitator, the ratio paddle dia/ tank dia is normally taken as
0.8
0.8
45
Hole diameter of the seive trays in the distillation column ranges from __________ mm.
3 to 12.5
3 to 12.5
46
Factor of safety (i.e., overdesign factor) in heat transfer equipments is about __________ percent more than the actual/theoretical design factor.
15-20
15-20
47
The minimum shell thickness for tank ≤ 15 metres diameter is limited to __________ mm, for reasons of elastic stability.
5
5
48
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
D/5 or minimum 2" to D.
D/5 or minimum 2" to D.
49
Brass valves are usually made for pipe sizes __________ inches.
≤2
≤2
50
In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement
results in higher shell side pressure drop.
results in higher shell side pressure drop.
51
Value of Peclet number = ∞, is the representative of
plug flow.
plug flow.
52
In most of the shell and tube heat exchangers, the tube pitch is generally __________ the tube diameter.
1.25-1.50 times
1.25-1.50 times
53
In a distillation column, bubble caps are located on trays with a pitch of __________ times the outside diameter of the caps.
1.3 to 2
1.3 to 2
54
__________ is the determining factor for the number of bubble caps to be used per tray.
Permissible slot velocity
Permissible slot velocity
55
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).
650
650
56
Normal screwed fittings are used for pipes upto a diameter of __________ inches.
3
3
57
For a given fluid, as the pipe diameter increases, the pumping cost
decreases.
decreases.
58
Maximum acceptable total liquid gradient over a tray is about __________ mm.
12.5
12.5
59
In case of a 'thin' pressure vessel, the ratio of its diameter to wall thickness is
> 10
> 10
60
High pressure fluid in a shell and tube heat exchanger should preferably be routed through the
tubes to avoid the expansion of high pressure shell construction.
tubes to avoid the expansion of high pressure shell construction.
61
Bubble cap tray is the most commonly used tray in large distillation column, because
of its flexibility and nearly constant efficiency under varying conditions of operation
of its flexibility and nearly constant efficiency under varying conditions of operation.
62
In the agitators, the power required will be changed with the increase of diameter of agitator (D) as
D^5
D^5
63
Apex angle of conical heads used in the bottom heads of chemical process equipments is usually
60°
60°
63
Circumferential (hoop) stress in a thin cylindrical vessel under internal pressure is __________ the longitudinal stress.
twice
twice
63
A pressure vessel is said to be made of 'thick' shell, if the ratio of its diameter to wall thickness is
10
10
63
Tube side heat transfer co-efficient for turbulent flow of liquid through tubes is proportional to
G^0.8
G^0.8
64
For storing hazardous chemicals in large storage tanks, the minimum safe distance between the two tanks should range between __________ times the tank diameter.
1 to 1.5
1 to 1.5
65
The absorption factor is defined as (where, S1 = slope of the equilibrium curve, S2 = slope of the operating line)
S1/S2
S1/S2
66
In a cylinderical vessel subjected to internal pressure, the longitudinal stress σL and the circumferential stress, σn are related by
σh = 2 σL
σh = 2 σL
67
Nominal size of a pipe is an indication of its __________ diameter.
approximate
approximate
68
The ratio of tube length to shell diameter in case of liquid shell and tube heat exchanger ranges from
4 to 8
4 to 8
69
What is the slope of the operating line in the stripping section of a distillation column ?
> 1
> 1
70
In a thin cylindrical shell, the hoop stress is __________ stress.
circumferential tensile
circumferential tensile
71
Commercial packed scrubbers are normally designed for a pressure drop range of __________ mm water coloumn per metre of packed height.
17-34
17-34
72
Rotary driers are most economically designed for the number of heat transfer units (HTU) from
1.5 to 2.5
1.5 to 2.5
73
The difficulty of liquid distribution in packed towers is accentuated, when the ratio of tower diameter to packing diameter is
< 7
< 7
74
With increase in temperature drop (in a shell and tube heat exchanger), the LMTD correction factor, FT
decreases very rapidly
decreases very rapidly
75
The normal range of velocity of steam in pipes is __________ m/sec.
80-100
80-100
76
The units of Young's modulus of elasticity and __________ are the same.
stress
stress
77
__________ liquor is best handled in a long tube vertical evaporator.
Foamy
Foamy
78
Theoretically calculated diameter of the stripping section of the continuous rectification column is __________ that of the enriching section.
more than
more than
79
Hold up of material in a operating rotary drier is in the range of
0.05 to 0.15
0.05 to 0.15
80
A binary liquid azeotropic mixture has boiling point higher than either of the components, when it shows __________ deviation from Raoult's Law.
negative
negative
81
The testing pressure of storage tanks and pressure vessels designed as per Indian standard codes should be about __________ times.the design pressure.
1.5 to 2
1.5 to 2
82
The ratio of down take area to cross-sectional area of the tube, for calendria type evaporator ranges from
0.5 to 1
0.5 to 1
83
At equal mass velocities, the values of film coefficients for gases as compared to that for liquids are generally.
lower
lower
84
The wall thickness of thin cylindrical shell with hemispherical ends is __________ that of the spherical ends.
more than
more than
85
Minimum tube pitch recommended for shell and tube heat exchangers is about __________ times the outside diameter of the tube.
1.25
1.25
86
Liquid redistribution should be done in a packed tower packed with raschig rings every 6 metres or __________ times the column diameter, whichever is lower.
2.5-3.0
2.5-3.0
87
Slope of countercurrent flow rotary drier is in the range of __________ meter/metre.
0 to 0.08
0 to 0.08
88
In case of saddle packing (e.g., berl and intralox saddles), the maximum size of the packing should not exceed __________ of the column diameter.
l/15th
l/15th
89
The minimum baffle height should be
twice the impeller diameter.
twice the impeller diameter.
90
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
1.5 d
1.5 d
91
The normal range of velocity of water in pipes is __________ m/sec.
1-2
1-2
92
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.
10 to 20
10 to 20
93
Heat transfer co-efficient for a horizontal condenser as compared to a vertical condenser operating under similar conditions is
about 3 times
about 3 times
94
The longitudinal stress induced in a thin walled cylinderical vessel under internal pressure is
pd/4t
pd/4t
95
In case of plain carbon steel, butt welded joints are used for shell plate thickness ≤ __________ cms.
3.8
3.8
96
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.
4
4
97
Hoop (circumferential) stress induced in a thin walled 'Horton Sphere' used for the storage of liquid ammonia under pressure is
pd/2t
pd/2t
98
The ratio, propeller agitator dia/ tank dia is normally taken as
0.15-0.30
0.15-0.30
99
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.
one fourth
one fourth
100
The ratio for the rate of washing to the final rate of filtration in a washing type of plate and frame filter is
0.25
0.25
101
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
1.5-2.5
1.5-2.5
102
Value of Peclet number = 0, is the representative of
complete back mixing.
complete back mixing.
103
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
0.3
0.3
104
Typical static submergence for bubble cap plate column operating at atmospheric pressure may be around
0.5"
0.5"
105
The length of straight rectangular weir used on cross-flow trays is generally __________ the column diameter.
0.6-0.8 times
0.6-0.8 times
106
Le/D for couplings and unions would be
negligible
negligible
107
What is the slope of the operating line in the rectifying section of a distillation coloumn ?
<1
<1
108
The minimum plate spacing in most of the pertroleum refinery distillation columns (of dia > 3 ft) is normally __________ inches.
18
18
109
For a given design of bubble cap, the number of bubble caps to be used per tray is set by the
allowable gas velocity through the slots.
allowable gas velocity through the slots.
110
The function of manholes provided in the shell of a distillation column is to
give access to the individual trays for cleaning, maintenance and installation.
give access to the individual trays for cleaning, maintenance and installation.
111
Back-trapping in a distillation column results due to
excessive liquid gradient over the tray.
excessive liquid gradient over the tray.
112
Diameter of bubble caps used in high pressure columns is __________ as compared to that used in identical vacuum columns.
more
more
113
The ideal size of round bubble caps to be used in industrial distillation column having a diameter of 3-6 metres is __________ cms.
15
15
114
Lap joints are preferred for plates having thickness __________ mm.
> 3
> 3
115
In a distillation column, minimum clearance to be maintained betweeen the overflow weir and the last row of the bubble caps is __________ cms.
7.5
7.5
116
Which of the following lengths of heat exchanger tubes are normally not used in practice ?
10 metres
10 metres
117
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
10000
10000
118
Equivalent diameter for heat transfer calculation for a duct of square cross-section having each side as 'd' will be
d
d
119
In a continuous distillation column, the optimum reflux ratio ranges from __________ times the minimum reflux ratio.
1.1 to 1.5
1.1 to 1.5
120
In the case of a shell and tube heat exchanger, the logarithmic mean temperature difference
is always less than arithmetic average value.
is always less than arithmetic average value.
121
In packed absorption tower, onset of flooding usually occurs at a pressure drop of about __________ mm of water column per metre height of packing.
50-75
50-75
122
For pipe flows, head is proportional to __________ at constant capacity (where D = pipe diameter ).
1/D^5
1/D^5
123
The minimum tray spacing in distillation column of diameter less than 3 ft is normally __________ inches.
6
6
124
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
0.1-0.2
0.1-0.2
125
Maximum size of the raschig rings used in a packed tower is about __________ of the column diameter.
1/30th
1/30th
126
The safe distance of habitation from a hazardous chemical plant (TLV of its product < 1000 ppm) should be about __________ kms.
25
25
127
The practical representative values of HETP for a number of commercial operations lies within a range of __________ metre.
0.4-0.9
0.4-0.9
128
Height of the flights in the rotary drier is in the range of
0.08 to 0.12 d
0.08 to 0.12 d
129
Vapor velocity in a distillation column for non-foaming mixture is in the range of __________ times the flooding velocity.
0.6 to 0.7
0.6 to 0.7
130
For turbine agitator, the impeller diameter is about
0.3 to 0.5 d
0.3 to 0.5 d
131
A binary liquid azeotropic mixture has boiling point lower than either of the components, when it shows __________ deviation from Raoult's Law.
positive
132
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
2^0.8
2^0.8
133
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.
increase by 2^1.6
increase by 2^1.6
134
The equivalent diameter for pressure drop is __________ that for heat transfer.
smaller than
smaller than
135
The approximate liquid depth in an agitation tank is equal to (where, d = tank diameter)
d
d
136
Baffle width is normally taken as __________ times the tank diameter.
0.1-0.12
0.1-0.12
137
A cylinderical 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
10mm
10mm
138
Lug support is meant for supporting __________ vessels.
small
small
139
Pressure drop per tray in the atmospheric distillation column is about __________ psi.
0.07 - 0.12
140
Welded joint efficiency in the design of chemical process equipment is taken as
0.85
0.85
141
The ratio of linear stress to linear strain is termed as the
modulus of elasticity
modulus of elasticity
142
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.
2.5 to 4.0
2.5 to 4.0
143
Bubble cap diameter used for the distillation column having diameter ranging from 1.5 to 4.5 metres is about __________ mm.
100mm
100mm
144
Tube height in a calendria type evaporator is normally less than __________ metres.
2m
2m
145
For a 25 mm hole drilled in plates to be rivetted, the shank diameter of the rivet should be __________ mm.
23mm
23mm
146
Pressure differential maintained across a continuous rotary vacuum filter is in the range of __________ mm Hg column.
250 to 500
147
In a double pipe (concentric) heat exchanger, the hydraulic radius for heat transfer (for a fluid flowing through the annulus) would be
more than that for fluid flow.
148
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.
two
two
149
What is the slope of the feed line, if the feed to a distillation column is a saturated liquid ?
∞
∞
150
Le/D for 90° elbow (medium radius) and 90°square elbow would be respectively around
25 and 60
151
What is the value of 'q' for saturated vapor feed to a distillation column ?(where q = fraction of the feed stream that is liquid.)
0
0
152
In hydrostatic testing of welded pipe (for leakage, strength etc.) the ratio of minimum hydrostatic test pressure to internal design pressure is around
1.5
1.5
153
Frame thickness in the plate and frame filter press is normally in the range of __________ inches.
0.25 to 8
0.25 to 8
154
Cylinderical shell thickness of rotary drier is generally __________ mm.
6-8
6-8
155
The ratio of lateral strain to linear strain is termed as the
Poisson's ratio
Poisson's ratio
156
A minimum clearance of about __________ mm is maintained between the distillation column wall and the bubble cap.
38
38
157
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
>1
>1
158
Le/D for a Tee (used as elbow, entering run) would be around
60
159
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").
equal to
160
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
bending
bending
161
Which of the following efficiencies can be greater than 100% ?
Murphree plate efficiency.
Murphree plate efficiency.
