PROCESS EQUIPMENT AND PLANT DESIGN Flashcards
1
Q
Power required for agitation depends upon the
A
all
2
Q
Tube height in a calendria type evaporator is normally less than __________ metres.
A
2
3
Q
Pick out the wrong statement.
a. Lug supports are less expensive than other type of supports.
b. A pipe is differentiated from a tube by the fact that a pipe has a
greater wall thickness compared to the tube.
c. A reducer is used to change the direction of a pipe in a straight run.
d. The method of fixing tubes to a tube sheet by expanding is called
‘tube rolling’.
A
A reducer is used to change the direction of a pipe in a straight run.
4
Q
For a 25 mm hole drilled in plates to be rivetted, the shank diameter of the rivet should be __________ mm.
A
23
5
Q
Optimum economic pipe diameter for fluid flow is determined by the
A
total cost considerations (pumping cost plus fixed cost of the pipe).
6
Q
Pressure differential maintained across a continuous rotary vacuum filter is in the range of __________ mm Hg column.
A
250 to 500
7
Q
Vertical storage vessels are never supported by __________ support.
A
saddle
8
Q
In a double pipe (concentric) heat exchanger, the hydraulic radius for heat transfer (for a fluid flowing through the annulus) would be
A
more than that for fluid flow.
9
Q
Elastic failure of a material occurs, when the tensile stress equals yield strength, yield point or the elastic limit. Also, the elastic failure occurs according to maximum strain theory, when the maximum tensile strain equals (where, σ = yield strength and E = modulus of elasticity)
A
σ/E
10
Q
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.
A
two
11
Q
What is the slope of the feed line, if the feed to a distillation column is a saturated liquid?
A
∞
12
Q
Filtration rate is affected by the
A
all
13
Q
Liquid gradient over a tray can be minimised by
A
all
14
Q
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
A
can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less.
15
Q
Le/D for 90° elbow (medium radius) and 90°square elbow would be respectively around
A
25 and 60
16
Q
__________ heat exchanger is also known as ‘hair pin type’ exchanger,
A
Double pipe
17
Q
What is the value of ‘q’ for saturated vapor feed to a distillation column ?(where q = fraction of the feed stream that is liquid.)
A
0
18
Q
In hydrostatic testing of welded pipe (for leakage, strength etc.) the ratio of minimum hydrostatic test pressure to internal design pressure is around
A
1.5
19
Q
Frame thickness in the plate and frame filter press is normally in the range of __________ inches.
A
0.25 to 8
20
Q
Cylinderical shell thickness of rotary drier is generally __________ mm.
A
6-8
21
Q
The ratio of lateral strain to linear strain is termed as the
A
Poisson’s ratio
22
Q
The distance between the centre of a rivet hole to the nearest edge of the plate is called
A
margin
23
Q
Mc Cable Thiele method used for finding theoretical stages in a distillation column assumes that the
A
all
24
Q
A minimum clearance of about __________ mm is maintained between the distillation column wall and the bubble cap.
A
38
25
Pick out the wrong statement. a. If sufficient residence time (around 8 seconds) is not proivided to the downcoming liquid in the downcomer, it may entrain some vapour. b. The liquid head in the downcomer should not be greater than one half the plate spacing to avoid flooding. c. The dischare end of the downcomer must project far enough into the tray liquid so that no gas bubbles can enter the open end and by pass the bubble caps.
d. None of these
none of these.
26
Pick out the wrong statement pertaining to shell and tube heat exchanger.
Bracket supports are used for horizontal shell, while saddle support is used for vertical shell.
27
Wind load consideration in the design of a support can be neglected, when the vessel is
short (< 2 m) and housed indoor.
28
Souders Brown equation is used for the calculation of the __________ in a continuous distillation column.
diameter of the bubble cap column
29
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
30
Steam economy is defined as the amount of evaporation per unit amount of steam used, while the capacity is the total evaporation obtained per hour. Use of multiple effect in evaporation
increases economy, does not affect the capacity
31
Le/D for a Tee (used as elbow, entering run) would be around
60
32
Log mean temperature difference in case of multi-pass shell and tube heat exchanger is always
less than arithmetic mean value.
33
Practical dividing line between a ductile and brittle materials is suggested, when the ultimate elongation is about 5%. Generally, larger the knuckle radius, stronger is the corner torus section of a head. The knuckle radius provided should be less than __________ of the head.
6% of I.D., 3 times the thickness whichever is larger
34
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
35
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
36
Scale up problem in design based on the similarity concept takes into account __________ similarity.
geometrical, kinematic, dynamic
37
__________ closure is the weakest enclosure for cylindrical vessels.
Conical or flat plate
38
Which of the following efficiencies can be greater than 100%?
Murphree plate efficiency.
39
Fresh water carrying pipelines in chemical industries are coloured with __________ color.
sea green
40
Which of the following material is seldom used for pressure vessel construction?
Rimmed steel
41
The ratio of shear stress to shear strain is called
shear modulus
42
25 per cent cut segmental baffle means that the baffle
height is 75% of the I.D. of the shell.
43
Liquid/petroleum fuel storage tanks are built underground (as in case of petrol pumps), when the storage capacity is less than __________ kilolitres.
45
44
Le/D for fully open globe value may be around
300
45
Lug support is
all
46
Pick out the wrong statement pertaining to the use of valve tray, seive tray and bubble cap trays in continuous distillation column.
Maintenance cost for valve and seive trays are comparatively more than bubble cap tray due to their relatively complicated construction features.
47
With increase in the number of shell passes, the value of FT
increases
48
Holes of a sieve tray are arranged in triangular pitch of __________ times the hole diameter.
2.5 to 5
49
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
50
The stress developed in a material without any permanent set is called the
elastic limit
51
In a shell and tube heat exchanger, the 'tube pitch' is defined as the
shortest centre to centre distance between adjacent tubes.
52
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?
Reflux is not a saturated liquid.
53
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)
η = 17 - 61.1 log μ
54
The value of fouling factor depends upon the
all
55
In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about __________ cms.
10
56
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
57
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
58
In a heat exchanger, shell side fluid velocity can be changed by changing the tube
layout, pitch
59
Where does the maximum tensile strength occur in a thick cylindrical vessel subjected to internal pressure?
At the inner surface.
60
It is not desirable to design a heat exchanger for LMTD correction factor, FT, of less than
0.8
61
A rivetted joint does not fail by __________ of rivets.
none of these
62
Triangular pitch tube layout as compared to square pitch in a shell and tube heat exchanger
permits the use of more tubes in a given shell diameter.
63
Bracket supports are the most suitable for supporting __________ vessels.
thick walled vertical
64
In a multipass shell and tube heat exchanger, the shell side cross flow area does not depend upon
none of these
65
Two iron pipes of the same nominal diameter but different schedule numbers will have the same
inside diameter
66
Steam side heat transfer co-efficient for design consideration under ordinary condition can be assumed to be about __________ kcal/hr.m2.°C.
7500
67
Pick out the wrong statement.
a. For all the cylindrical process vessels operating above atmospheric
pressure, formed heads are used for closing the vessel.
b. Fouling factor of river water is less than that of sea water.
c. Risers provided in bubble cap trays in the distillation column
facilitate the flow of both liquid and vapor.
d. both (b) and (c).
Fouling factor of river water is less than that of sea water, Risers provided in bubble cap trays in the distillation column facilitate the flow of both liquid and vapor
68
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
69
In chemical process equipments, the conical bottom heads used, usually has an apex angle of
60°
70
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
71
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
less
72
Correct use of 'factor of safety' is very important in equipment design. It is defined as the ratio of the
ultimate stress to working stress.
73
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
74
__________ tray arrangement is recommended for distillation column having diameter upto 4 ft.
Cross flow
75
What is the value of 'q' for saturated liquid feed to a distillation column?
1
76
In perforated plate towers, the
all
77
The main purpose of providing stepping on the trays is to
facilitate handling of large flow rate of liquid.
78
The operating pressure drop range in a bag filter is about __________ mm water gauge.
50-150
79
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.
Ellipsoidal
80
For laminar flow (NRe < 2100) in steel pipe, the optimum inside pipe diameter is given by
Di, opt = 3 Q0.36 ρ0.18
81
Pick out the correct statement.
a. When highly corrosive fluids are to be handled, the plate towers
prove to be cheaper and easier to construct than packed tower.
b. Packed towers are generally preferred over plate towers, if the
liquids have a foaming tendency.
c. The pressure drop through the packed towers is generally more than
the pressure drop through plate towers designed for same duty.
d. none of these.
Packed towers are generally preferred over plate towers, if the liquids have a foaming tendency.
82
Wall thickness of schedule 40 pipe as compared to that of schedule 80 pipe is
less
83
Pick out the wrong statement pertaining to the design of a basket type evaporator.
It is used for high viscosity liquor having large rate of scaling.
84
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.
none of these.
85
Speed of the drum of the rotary vacuum filter normally ranges from __________ rpm.
0.1 to 2
86
A stuffing box is used for
prevention of fluid leakage around moving parts.
87
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
88
Pick out the wrong statement.
In an agitated vertical cylinderical reaction vessel, the
dished bottom vessel has very high power consumption.
89
Needle valves are generally not used for
very large diameter pipes.
90
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
all
91
Pick out the wrong statement.
a. Safety valves are provided in heat exchangers for removal of nonconden-sables.
b. Liquid metals and dowtherm are used for very high temperature
heating.
c. In a shell and tube heat exchanger, high pressure fluid is generally
routed through the tube.
d. A loop seal or U-seal is provided in a vertical condenser sub-cooler
to prevent quick draining of the condensate.
Safety valves are provided in heat exchangers for removal of non-conden-sables.
92
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
93
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
central dished section and corner torus section.
94
Number of evaporators which can be used in service in a multiple effect evaporation system is limited by the
practical limit reached, due to low heat transfer rate because of inadequate temperature difference, economic limit reached, when the plant cost exceeds the saving of steam
95
Which of the following is used to set the diameter of the distillation column?
Allowable vapour velocity.
96
Ponchon Savarit method is based on the use of enthalpy concentration diagram, which contains the bubble point curve (saturated liquid curve), dew point curve (saturated vapour curve) and equilibrium tie lines. As compared to McCabe-Thiele's method, this method
all
97
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
smaller reactor should come first.
98
In a shell and tube heat exchanger, tube side __________ of the mass velocity.
heat transfer co-efficient is proportional to 0.8th power, pressure drop is proportional to the square
99
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?
Sorel-Lewis method.
100
Saddle supports are used for supporting __________ vessels.
horizontal cylinderical
101
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
102
In packed towers provided with saddle packing, liquid redistributors are positioned at every __________ times column diameter or 6 metres whichever is less.
5-8
103
Optimum reflux ratio in a continuous distillation column is determined by the
total cost consideration (fixed cost of the column plus the cooling water & steam cost).
104
Cooling water fouling factors vary in the range of 0.001 to 0.003
(BTU/hr.ft2 . °F)-1
105
Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter)
0.2 D
106
The maximum liquid gradient over a tray must not exceed
0.5" -1.25".
107
An underdesigned steam trap will
back up condensate and cause water hammer in steam line.
108
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)
109
Speed of industrial paddle agitator ranges from __________ rpm.
20 to 100
110
_________ strain is measured using a 'strain rosetter'.
Linear
111
Thin spherical shells subjected to internal pressure, develop __________ stresses.
radial
112
With increase in the reflux ratio for a fixed production from a continuous binary distillation column, the __________ decreases.
fixed charges initially
113
The slope of operating line in the rectifying section of a distillation column is unity, if the reflux ratio is
∞
114
Vertical vessels are not supported by
saddles
115
With increase in pressure drop (for a given particle size), the dust collection efficiency of a cyclone separator will
increase
116
Spherical shaped pressure vessel is considered to be the most ideal, because it can
withstand higher pressure for a given metallic shell thickness.
117
An adequate clearance between the tray and the shell wall of a distillation column is provided to
allow for thermal expansion and facilitate installation.
118
Overall tray efficiency of a distillation column is the ratio of the number of
ideal trays required to the number of real trays required.
119
Pick out the wrong statement about the design of a sieve plate column.
Minimum recommended downcomer residence time for the disengagement of entrained vapour is the same for both foaming and non-foaming liquids, which is about 20 seconds.
120
Generally, no corrosion allowance in wall thickness of a part is required, if the thickness is more than __________ mm.
30
121
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
122
In a __________ rivetted joint, the rivets in the various rows are opposite to each other.
chain
123
Pick out the wrong statement
a. The tensile strength of a brittle material is less than its compressive
strength.
b. The compressive strength of a ductile materia] is less than its tensile
strength.
c. In a thick cylindrical shell, the hoop stress is maximum at the inner
radius.
d. The value of crushing load is more than that of buckling load for
long colmns.
The value of crushing load is more than that of buckling load for long colmns.
124
Generally, elliptical dished heads
all
125
Pick out the wrong statement pertaining to the comparative evaluation of performance of the packed tower and the plate tower.
The total weight of a dry plate tower is usually much more than that of a dry packed tower designed for the same duty.
126
The circumferential (hoop) stress in a thin walled cylinderical vessel under internal pressure is
pd/2t
127
Le/D for fully open gate valves would be
much less (say 2% than that for fully open globe valves), around 7.
128
LMTD correction factor is used in heat exchanger design for
multipass shell and tube heat exchanger.
129
Floating head heat exchangers are used for the
cases where temperature difference between the shell and the tubes is more (>50°C).
130
The most common standard size of bubble caps used in industrial operation is
6" dia cap with 4" dia riser.
131
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.
nozzle or rim
132
In case of a continuous distillation column, increase in reflux ratio may result in the
all
133
In a distillation column, the minimum residence time for liquid in the downspout is about __________ seconds.
8
134
Thickness of the frame of a plate and frame filter as compared to that of plates is
more
135
Which of the following factors affect the pressure drop in a co-current gas-liquid absorption packed tower?
all
136
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
137
Rivets are generally specified by the
shank diameter
138
Length to diameter ratio of most rotary driers is in the range of
4 to 10
139
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
140
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
141
Ratio of tube length to shell diameter for a shell and tube heat exchanger is
4 : 1 to 8 : 1 for liquid-liquid exchanger, < 4 : 1 for gas-gas exchangers
142
The dust collection efficiency of a cyclone separator
none of these.
143
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
144
Which of the following types of reactors is the safest from operation point of view?
A vapor phase reactor.
145
In a bag filter, the pressure drop increases directly as the
density of the gas and inversely as viscosity of the gas.
146
The LMTD correction factor (FT) is applied in __________ heat exchangers.
all multipass
147
Movement of pipeline caused by thermal expansion is taken care by providing
all
148
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.
149
In the design of a paddle agitator, the ratio paddle dia/tank dia is normally taken as
0.8
150
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.
damaging
151
Hole diameter of the seive trays in the distillation column ranges from __________ mm.
3 to 12.5
152
Factor of safety (i.e., overdesign factor) in heat transfer equipments is about __________ percent more than the actual/theoretical design factor.
15-20
153
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
d1/(d1+d2)
154
In actual operation of distillation column, the vapour is not distributed uniformly among the bubble caps, primarily because of the
liquid gradient on the tray.
155
The minimum shell thickness for tank ≤ 15 metres diameter is limited to __________ mm, for reasons of elastic stability.
5
156
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 5D.
157
Brass valves are usually made for pipe sizes __________ inches.
≤2
158
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
remains same
159
In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement
results in higher shell side pressure drop.
160
Pick out the wrong statement about routing of fluids in a shell and tube heat exchanger.
Higher pressure fluid stream should be routed through the shell side.
161
The necessary wall thickness for a metallic storage vessel is a function of the
all
162
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.
(1/n)th
163
Pick out the wrong statement.
a. In a flanged and standard dished head, the crown radius is ≤ shell
outside diameter.
b. In a flanged and shallow dished head, the crown radius is > shell
outside diameter.
c. Flat head covers are most suitable for larger vessels operating at very
high pressure.
d. Flanged only head is a type of flat head in which gradual change in
the shape at the centre results in reduced local stresses.
Flat head covers are most suitable for larger vessels operating at very high pressure.
164
Pick out the wrong statement pertaining to the design of a horizontal tube evaporator.
Liquor flows inside the tube, while the steam is outside submerging the tube.
165
Weep holes provided in the plates of a distillation column
all
166
Steam is preferred to be used as a heating medium in heat exchangers, because of its
high latent heat.
167
__________ shapedroof is the most commonly used roof for cylinderical storage tanks.
Conical
168
Pick out the wrong statement pertaining to 'Horton sphere' used for the storage of liquid ammonia.
Horton sphere is used for the storage of liquid at sub-zero temperature at very high pressure upto 200 kg/cm2 .
169
Value of Peclet number = ∞, is the representative of
plug flow.
170
Le/D for a Tee (used as elbow, entering branch) would be
more than that for Tee (used as elbow, entering run), around 90
171
In most of the shell and tube heat exchangers, the tube pitch is generally __________ the tube diameter.
1.25-1.50 times
172
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
173
1.2 to 3.8 cms is the value of the
all
174
Accidents in chemical plants are mostly due to
faulty operating procedures.
175
For identical operating conditions, the pressure drop over __________ tray is the highest out of the following.
bubble cap
176
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
(ph - dt)/ph
177
__________ is the determining factor for the number of bubble caps to be used per tray.
Permissible slot velocity
178
Pick out the wrong statement about distillation operation
Flash distillation, differential distillation & steam distillation are all continuous distillation processes.
179
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
180
Which of the following is the best tube material from thermal conductivity point of view alone?
Copper
181
Normal screwed fittings are used for pipes upto a diameter of __________ inches.
3
182
In a shell and tube heat exchanger, the clearance of the tube is generally
not less than one-fourth of the tube diameter or 3/16".
183
Diameter of the seive tray column is determined by the
upper limit of the vapour velocity.
184
For a given fluid, as the pipe diameter increases, the pumping cost
decreases.
185
Maximum acceptable total liquid gradient over a tray is about __________ mm.
12.5
186
In case of a 'thin' pressure vessel, the ratio of its diameter to wall thickness is
> 10
187
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.
188
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.
189
In common bubble cap distillation column design practice, riser area is approximately equal to (where, Aa = Annular passage area, and Sa = Slot area)
Aa = Sa
190
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
hG = 1.004G^0.37
191
In the agitators, the power required will be changed with the increase of diameter of agitator (D) as
D^5
192
Apex angle of conical heads used in the bottom heads of chemical process equipments is usually
60°
193
Pressure drop due to pipe fittings can be estimated by the equation where, Le = equivalent length of straight pipeline which will incur the same frictional loss as the fitting and D = diameter of the fitting. The value of Le/D (dimensionless) for 45° elbow and 180° close return bends would be respectively around
45 and 75
194
A pressure vessel is said to be made of 'thick' shell, if the ratio of its diameter to wall thickness is
10
195
Rate of filtrate delivery is inversely proportional to the
filtering area & the pressure difference driving force, viscosity of filtrate.
196
Tube side heat transfer co-efficient for turbulent flow of liquid through tubes is proportional to
G^0.8
197
Circumferential (hoop) stress in a thin cylindrical vessel under internal pressure is __________ the longitudinal stress.
twice
198
The dust collection efficiency of electrostatic precipitator increases with increase in the
electrode area.
199
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
200
Which of the following factors determine the amount of entrainment in a distillation column?
all
201
The absorption factor is defined as (where, S1 = slope of the equilibrium curve, S2 = slope of the operating line)
S1/S2
202
In shell and tube heat exchangers, straight tie rods are used to
hold baffle in space.
203
In a rotary drier, the average retention time of solid is(where Z = length of the drier, metres ρ = apparent solid density, kg/m3 L = flow rate of dry solids, kg/see. m2 drier cross-section H = hold up of solid.)
Z.H.p/L
204
In case of design of a shell and tube heat exchanger,
all
205
In a cylinderical vessel subjected to internal pressure, the longitudinal stress σL and the circumferential stress, σn are related by
σh = 2 σL
206
Nominal size of a pipe is an indication of its __________ diameter.
approximate
207
Excessive liquid gradient on a tray may result in the
all
208
The ratio of tube length to shell diameter in case of liquid shell and tube heat exchanger ranges from
4 to 8
209
What is the slope of the operating line in the stripping section of a distillation column?
> 1
210
__________ shaped roof is most commonly used for cylindrical tanks.
Cone
211
In a thin cylindrical shell, the hoop stress is __________ stress.
circumferential tensile
212
Commercial packed scrubbers are normally designed for a pressure drop range of __________ mm water coloumn per metre of packed height.
17-34
213
The retention time of material in a rotary dryer depends upon its
all
214
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.
all
215
Rotary driers are most economically designed for the number of heat transfer units (HTU) from
1.5 to 2.5
216
The difficulty of liquid distribution in packed towers is accentuated, when the ratio of tower diameter to packing diameter is
< 7
217
A forced circulation long tube vertical evaporator as compared to the natural circulation evaporator
employs high velocity, high heat transfer rate and less heating surface requirement, employs a centrifugal pump placed between external downtake from vapor drum and inlet to tube bundle.
218
An increase in the liquid resistance to interphase mass transfer and a resultant reduction in plate efficiency is caused by
all
219
In the design of a bag filter, the gas temperature is an important consideration, as it affects the
all
220
With increase in temperature drop (in a shell and tube heat exchanger), the LMTD correction factor, FT
decreases very rapidly
221
The normal range of velocity of steam in pipes is __________ m/sec.
80-100
222
__________ dished head is the strongest of all.
Hemispherical
223
Pick out the correct statement.
a. It is preferred to use a vertical condenser for condensation of vapor
from a distillation column without sub-cooling
b. Draining of residual liquid on tray during shut down of distillation
column is facilitated by weep holes.
c. Random packing a packed tower offers the advantage of lower
pressure drop and higher throughput of fluids as compared to
regular/stacked packing.
d. Risers are generally not connected to the plate in a distillation
coloumn by bolts, rivets or welding.
Risers are generally not connected to the plate in a distillation coloumn by bolts, rivets or welding.
224
"A claming section" before the liquid flows into the downcomer is privided to
permit release of entrained vapour in the liquid.
225
The units of Young's modulus of elasticity and __________ are the same.
stress
226
In the design of a shell and tube heat exchanger, the corrosion allowance
all
227
Vertical condenser is advantageous to the horizontal condenser from operation point of view, when
both the functions of condensation & sub cooling are carried out in a single unit.
228
Hazards associated with the relief valve leakage for extremely hazardous material storage can be taken care of by providing
rupture diaphragm
229
Minimum baffle spacing recommended in a shell and tube heat exchanger is equal to
5 cms
230
__________ liquor is best handled in a long tube vertical evaporator.
Foamy
231
Theoretically calculated diameter of the stripping section of the continuous rectification column is __________ that of the enriching section.
more than
232
Hold up of material in a operating rotary drier is in the range of
0.05 to 0.15
233
A binary liquid azeotropic mixture has boiling point higher than either of the components, when it shows __________ deviation from Raoult's Law.
negative
234
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
235
Flanges are connected to pipes by
all
236
The ratio of down take area to cross-sectional area of the tube, for calendria type evaporator ranges from
0.5 to 1
237
Shortest distance between two tubes is
called tube clearance.
238
__________ tower is the most suitable gas-liquid contacting device involving highly corrosive fluids.
Packed
239
At equal mass velocities, the values of film co-efficients for gases as compared to that for liquids are generally.
lower
240
The ratio of the largest load in a test to the original cross-sectional area of the test specimen is called the __________ stress.
ultimate
241
Baffle spacing is generally __________ the I.D. of the shell.
not greater than, not less than one fifth of
242
The wall thickness of thin cylindrical shell with hemispherical ends is __________ that of the spherical ends.
more than
243
A 'rupture disc' is provided in chemical equipments as an accessory meant for
relieving excess pressure.
244
In a vertical short tube evaporator (Calendria type), the
all
245
In a multipass shell and tube heat exchanger, the problem of differential expansion between the shell and tube passes is taken care of by using a
U-bend or floating head tube sheet
246
In a shell and tube heat exchanger, the shortest centre to centre distance between the adjacent tubes is
called tube pitch.
247
Any shell opening greater than 5 cms for a storage tank must be reinforced for reason of
preventing the local overstressing of the shell around the opening.
248
Minimum tube pitch recommended for shell and tube heat exchangers is about __________ times the outside diameter of the tube.
1.25
249
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
250
Slope of countercurrent flow rotary drier is in the range of __________ meter/metre.
0 to 0.08
251
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
252
Seamless pipe is made
by extrusion & casting into static and centrifugal molds, by forging a solid round, piercing it by simultaneously rotating & forcing it over a piercer point and further reducing it by rolling gas drawing.
253
The thermal stress in a metallic bar does not depend upon the
cross-sectional area.
254
The minimum baffle height should be
twice the impeller diameter.
255
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)
Di, opt = 3.9 Q0.45 ρ0.13
256
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
257
The normal range of velocity of water in pipes is __________ m/sec.
45293
258
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?
Flat plate extending across the wall
259
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
irrespective of the shape of the vessel.
260
In a __________ rivetted joint, the number of rivets decreases from the innermost row to the outermost row.
diamond
261
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
262
Heat transfer co-efficient for a horizontal condenser as compared to a vertical condenser operating under similar conditions is
about 3 times
263
Pick out the wrong statement pertaining to the design of the distillation column.
none of these.
264
The longitudinal stress induced in a thin walled cylinderical vessel under internal pressure is
pd/4t
265
In distillation columns, bubble caps are held in place over trays by
a hold down bar, bolts
266
The buckling tendency of compression members is always in the direction of the
least radius of gyration.
267
In case of plain carbon steel, butt welded joints are used for shell plate thickness ≤ __________ cms.
3.8
268
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
269
Hoop (circumferential) stress induced in a thin walled 'Horton Sphere' used for the storage of liquid ammonia under pressure is
pD/2t
270
When one of the fluids is highly corrosive and has fouling tendency, it should
preferably flow inside the tube for its easier internal cleaning.
271
The raio, propeller agitator dia/tank dia is normally taken as
0.15-030
272
A/an __________ is used for changing the direction of a pipeline.
elbow
273
Maximum plate efficiency is achieved in case of __________ flow.
cross
274
The LMTD correction factor (FT) is defined as the
ratio of true temperature difference to the LMTD.
275
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
276
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
277
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
278
Value of Peclet number = 0, is the representative of
complete back mixing.
279
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
280
Removable connection of tubes to tube sheet is called
ferrule
281
Stress-strain diagram for low carbon steel/mild steel is shown below in the Fig.
https://www.indiabix.com/_files/images/chemical-engineering/process-equipment-and-plant-design/572-178-1.png The point 'A' on the Fig. represents the
elastic limit
282
Typical static submergence for bubble cap plate column operating at atmospheric pressure may be around
2.5"
283
In the allocated cap area, bubble caps are generally arranged on equilateral triangular pitch. Number of caps fixed on a plate is with a
clearance of 25-75 mm. or cap pitch of 1.3-2 times the cap diameter.
284
The length of straight rectangular weir used on cross-flow trays is generally __________ the column diameter.
0.6-0.8 times
285
Le/D for couplings and unions would be
negligible
286
What is the slope of the operating line in the rectifying section of a distillation coloumn?
<1
287
Stage efficiency for packed tower varies with the
all
288
The minimum plate spacing in most of the pertroleum refinery distillation columns (of dia > 3 ft) is normally __________ inches.
18
289
Joint efficiency (J) for a seamless pipe is
1
290
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.
291
The shell side pressure drop in a shell and tube heat exchanger is maximum for __________ baffle.
orifice
292
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.
293
Back-trapping in a distillation column results due to
excessive liquid gradient over the tray.
294
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?
0.8
295
Diameter of bubble caps used in high pressure columns is __________ as compared to that used in identical vacuum columns.
more
296
The ideal size of round bubble caps to be used in industrial distillation column having a diameter of 3-6 metres is __________ cms.
15
297
Lap joints are preferred for plates having thickness __________ mm.
> 3
298
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
299
Which of the following lengths of heat exchanger tubes are normally not used in practice ?
10 metres
300
A pipe is generally made of circular cross-section, because a circular cross-section has the
higher structural strength, lowest surface area requirement for a given volume.
301
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
302
Equivalent diameter for heat transfer calculation for a duct of square cross-section having each side as 'd' will be
d
303
A cylindrical storage tank can have a self supported conical roof,
if its diameter is less than 15-20metres.
304
For high pressure process equipments/vessels, the connected nozzle should be
flanged
305
Smoker's equation for the calculation of number of equilibrium stages in a continuous binary distillation column is used, when the
relative volatility is close to one (e.g., separation of close boiling isomers).
306
Column support for the roof of cylindrical storage tank must be provided for
large diameter tanks.
307
For a cylinderical internally pressurised vessel, which of the following closure types would withstand highest pressure, if each closure is of the same material and thickness?
ellipsoidal (2 : 1)
308
In inclined long tube vertical evaporators, the tubes are inclined at an angle of
45°
309
In a continuous distillation column, the optimum reflux ratio ranges from __________ times the minimum reflux ratio.
1.1 to 1.5
310
The wall thickness for a large high pressure pipeline is determined by the consideration of the
circumferential pipewall tension.
311
In the case of a shell and tube heat exchanger, the logarithmic mean temperature difference
is always less than arithmetic average value.
312
Skirt support is the most suitable for supporting __________ vessels.
tall vertical
313
Baffles may be eliminated for
high viscosity liquids (> 600 poise).
314
Generally, as the length of the liquid path on a tray is increased beyond 5 ft, the overall column efficiency
increases
315
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
316
For pipe flows, head is proportional to __________ at constant capacity (where D = pipe diameter).
1/D5
317
Friction factor for turbulent flow in a new pipe is given by
f = 0.04/(NRe)^0.16
318
The minimum tray spacing in distillation column of diameter less than 3 ft is normally __________ inches.
6
319
Oxygen carrying pipelines in chemical industries are coloured with __________ colour.
blue
320
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
321
Pick out the wrong statement about the design of seive plate column and the bubble cap column.
Weir height for a bubble cap plate column is the same as that for a seive plate column.
322
Maximum size of the raschig rings used in a packed tower is about __________ of the coloumn diameter.
1/30th
323
Longitundinal stress induced in a thin walled cylindrical storage vessel is
pD/4t
324
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.
thermal
325
The safe distance of habitation from a hazardous chemical plant (TLV of its product < 1000 ppm) should be about __________ kms.
25
326
Pick out the wrong statement pertaining to a shell and tube heat exchanger.
Disk and doughnut baffle is the most commonly used baffle.
327
Corrosion allowance in the design of pressure vessel/chemical equipment is not necessary, if
wall thickness is > 30 mm, material of construction is high alloy steel.
328
Maximum allowable vapour velocity in a bubble cap tower is determined by the
entrainment considerations.
329
Normally, the plate thickness of the bottoms and roofs of vertically cylindrical storage vessels as compared to that of the cylindrical shell is
less
330
The practical representative values of HETP for a number of commercial operations lies within a range of __________ metre.
0.4-0.9
331
Of the pressure vessels, with same thickness but different diameters, which one withstands higher pressure?
Smaller dia vessel.
332
Reflux ratio variation in a distillation column is between
minimum and infinity
333
Width and depth of grooves in the tube sheet holes normally are __________ inch respectively.
1/8 and 1/64
334
In condenser, the cooling water is passed in the tube side in a pass arrangement, because
it reduces heat transfer area.
335
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.
1/10-1/15th
336
Height of the flights in the rotary drier is in the range of
0.08 to 0.12 d
337
Vapor velocity in a distillation column for non-foaming mixture is in the range of __________ times the flooding velocity.
0.6 to 0.7
338
Cylindrical storage tanks used for the storage of volatile liquids (e.g., naphtha) have __________ roofs.
floating
339
Larger depth of liquid on the trays of a distillation column
leads to high tray efficiency, results in higher pressure drop per tray.
340
Pick out the wrong statement.
a. Plate efficiency increases with increase in superficial vapour
velocity till entrainment limit.
b. Increase in depth of the liquid about the slots increases the plate
efficiency, particularly if the liquid depth is < 1".
c. Too small a plate spacing can cause a low efficiency, if the vapour
velocity is greater than the allowable value.
d. none of these.
none of these.
341
Pick out the wrong statement.
a. In practical operation, distillation towers having diameter 3-6 metres
equipped with bubble cap (round) size of 15 cms are used.
b. Height of packing in a packed tower is about 3 times the column
diameter for raschig rings and about 5 to 10 times the column
diameter for saddle packing.
c. In a seive tray, the minimum hole diameter is equal to the tray
thickness.
d. In a stainless steel seive tray, the minimum hole diameter is equal to
10 times the plate thickness.
In a stainless steel seive tray, the minimum hole diameter is equal to 10 times the plate thickness.
342
In the downcomer of a distillation column, the minimum recommended residence time is about __________ seconds.
5
343
For identical situation, condensing film coefficient in case of a horizontal condenser is almost __________ the value expected in case of vertical condenser.
thrice
344
Diameter of rivet hole (d, mm) and the plate thickness (t, mm) are related by Unwin's formula as
d = 1.6 sqrt(t)
345
A binary liquid azeotropic mixture has boiling point lower than either of the components, when it shows __________ deviation from Raoult's Law.
positive
346
In which of the following evaporators, steam is fed inside the tube while the liquor is outside the tube?
Horizontal tube evaporator
347
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
348
In a multipass shell and tube heat exchanger, the baffles on shell side is primarily provided for
creating turbulence.
349
For turbine agitator, the impeller diameter is about
0.3 to 0.5 d
350
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
351
Pick out the wrong statement pertaining to the design of a long tube vertical evaporator.
none of these.
352
Which of the following is the most common type of baffle used in industrial shell and tube heat exchanger?
25% cut segmental baffle.
353
What is the minimum recommended ligament for square pitch arrangement in case of heat exchangers?
6.5 mm
354
Pick out the correct statement
a. Centre to centre distance between two consecutives rivets in a row
is called the pitch.
b. A rivetted joint made in overlapping plates is called butt joint.
c. Hole size drilled in rivetted plates is less than the actual size of the
rivet.
d. none of these
Centre to centre distance between two consecutives rivets in a row is called the pitch.
355
Safety valves are provided in chemical equipments to guard against excessive
pressure/pressure fluctuation
356
The equivalent diameter for pressure drop is __________ that for heat transfer.
smaller than
357
Most of the storage vessels/tanks are made cylindrical, because of the fact that a cylinder
has greater structural strength, is easy to fabricate.
358
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
static submergence
359
Liquid gradient over the tray results due to the
resistance offered to flow of liquids by caps & risers and the flow of gas.
360
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?
To increase the tube side heat transfer co-efficient by inducing turbulence.
361
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.
80
362
The approximate liquid depth in an agitation tank is equal to (where, d = tank diameter)
d
363
Baffle width is normally taken as __________ times the tank diameter.
0.1-0.12
364
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
10 mm
365
Which of the following packing materials provides for maximum mass transfer?
Cross-partition rings.
366
__________ of water makes it a widely used coolant in heat exchangers.
High specific heat
367
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)
4 A/P
368
Fouling factor must be included in the calculation of over all design heat transfer coefficient, when the liquid
containing suspended solids flows at low velocity.
369
Lug support is meant for supporting __________ vessels.
small
370
Overall mass transfer co-efficient in case of absorption of __________ in water is based on the gas film co-efficient only, as the mass transfer process is gas film (phase) controlling.
NH3
371
Which tube arrangement in a heat exchanger would facilitate highest heat transfer rate?
Triangular pitch.
372
In case of 1.5" heat exchanger tubes, the inside flow area __________ with decrease in BWG.
decreases
373
Cylindrical pressure vessels in horizontal condition is generally supported on a __________ support.
saddle
374
Pressure drop per tray in the atmospheric distillation column is about __________ psi.
0.07 - 0.12
375
Welded joint efficiency in the design of chemical process equipment is taken as
0.85
376
The thickness of segmental baffles (25 -35% cut truncated plates usually) is generally __________ the tube wall thickness.
twice
377
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
1
378
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.
considerably more than 9
379
The ratio of linear stress to linear strain is termed as the
modulus of elasticity
380
__________ head is the most economical for cylindrical vessels designed for operating at high pressure (> 15 atm.).
Ellipsoidal
381
Bubble cap plate column is
a finite stage contactor.
382
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
383
Pick out the wrong statement.
a. Rivetting provides a permanent fastening method.
b. The joint made by overlapping of one plate over the other, and then
rivetting the two plates together with two rows of rivets is called
'double rivetted butt joint'.
c. Shank diameter of the rivets should be less than the size of the hole
drilled in the plate for rivetting.
d. The efficiency of a rivetted joint is the ratio of the strength of the
rivetted joint to the strength of the solid plate.
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'.
384
The force due to wind load acting on a tall vessel depends upon its
all
385
Bubble cap diameter used for the distillation column having diameter ranging from 1.5 to 4.5 metres is about __________ mm.
100
386
