Process Equipment and Plant Design Flashcards
1
Q
With increase in the reflux ratio for a fixed production from a continuous binary distillation column, the __________ decreases.
A
fixed charges initially
2
Q
Speed of industrial paddle agitator ranges from __________ rpm.
A
20 to 100
3
Q
__________ strain is measured using a ‘strain rosetter’.
A
linear
4
Q
The slope of operating line in the rectifying section of a distillation column is unity, if the reflux ratio is
A
∞
5
Q
Vertical vessels are not supported by
A
saddles
6
Q
With increase in pressure drop (for a given particle size), the dust collection efficiency of a cyclone separator will
A
increase
7
Q
Spherical shaped pressure vessel is considered to be the most ideal, because it can
A
withstand higher pressure for a given metallic shell thickness.
8
Q
An adequate clearance between the tray and the shell wall of a distillation column is provided to
A
allow for thermal expansion and facilitate installation.
9
Q
Overall tray efficiency of a distillation column is the ratio of the number of
A
ideal trays required to the number of real trays required.
10
Q
Pick out the wrong statement about the design of a sieve plate column.
A. An increased weir height improves the tray efficiency at the cost of high plate pressure drop; optimum wear height being 40-90 mm for column pressure above atmospheric and 6-12 mm for vacuum columns.
B. For segmental downcomers, the chord length is 60-80% of the column diameter. An initial value of downcomer area of 12% is taken in the design.
C. Width of the calming section provided at the inlet and outlet sides of the plate is 75 mm for column diameter below 1.5 metres and 100 mm for larger diameter columns.
D. 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.
A
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.
11
Q
Generally, no corrosion allowance in wall thickness of a part is required, if the thickness is more than __________ mm.
A
30
12
Q
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.
A
0.1 to 0.25
13
Q
In a __________ rivetted joint, the rivets in the various rows are opposite to each other.
A
chain
14
Q
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 material 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.
A
The value of crushing load is more than that of buckling load for long colmns.
15
Q
Pick out the wrong statement pertaining to the comparative evaluation of performance of the packed tower and the plate tower.
A. Plate tower is perferred, if interstage cooling is required to remove heats of reaction or solution.
B. Plate tower is preferred over packed tower, if the operation involves liquids containing dispersed solids.
C. The total weight of a dry plate tower is usually much more than that of a dry packed tower designed for the same duty.
D. In operations involving large temperature changes. (e.g. distillation), plate towers are preferred over packed towers as the packing may be crushed due to large temperature changes.
A
The total weight of a dry plate tower is usually much more than that of a dry packed tower designed for the same duty.
16
Q
The circumferential (hoop) stress in a thin walled cylinderical vessel under internal pressure is
A
pd/2t
17
Q
Floating head heat exchangers are used for the
A
cases where temperature difference between the shell and the tubes is more (>50°C).
18
Q
The most common standard size of bubble caps used in industrial operation is
A
6” dia cap with 4” dia riser.
19
Q
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.
A
nozzle or rim
20
Q
In case of a continuous distillation column, increase in reflux ratio may result in the
A. lower fixed charges for the column.
B. greater cost for the reboiler heat supply.
C. greater cost for the condenser coolant.
D. all (a), (b) and (c).
A
all
21
Q
In a distillation column, the minimum residence time for liquid in the downspout is about __________ seconds.
A
8
22
Q
Which of the following factors affect the pressure drop in a co-current gas-liquid absorption packed tower ?
A. Size, shape, orientation and surface of the packing particles.
B. Density and viscosity of fluids.
C. Fluid flow rates.
D. All (a), (b) and (c).
A
all
23
Q
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.
A
1.25 to 3.125
24
Q
Rivets are generally specified by the
A
shank diameter
25
Length to diameter ratio of most rotary driers is in the range of
4-10
26
Needle valves are generally not used for
very large diameter pipes.
27
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 of the above
28
Pick out the wrong statement.
Safety valves are provided in heat exchangers for removal of non-conden-sables.
Liquid metals and dowtherm are used for very high temperature heating.
In a shell and tube heat exchanger, high pressure fluid is generally routed through the tube.
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.
29
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
30
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.
31
Which of the following is used to set the diameter of the distillation column ?
Allowable vapour velocity.
32
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
A. is more accurate in finding the number of equilibrium stages.
B. accounts for the enthalpy changes in the process.
C. facilitates direct calculation of heat load on reboiler & condenser from, the diagram used in this method.
D. all 'a', 'b' & 'c'.
all of the above
33
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.
34
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.
35
Saddle supports are used for supporting __________ vessels.
horizontal cylinderical
36
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.
15-30
37
In packed towers provided with saddle packing, liquid redistributors are positioned at every __________ times column diameter or 6 metres whichever is less.
5-8
38
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).
39
Cooling water fouling factors vary in the range of 0.001 to 0.003
(BTU/hr.ft2 . °F)-1
40
Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter )
0.2D
41
The maximum liquid gradient over a tray must not exceed
0.5" -1.25".
42
An underdesigned steam trap will
back up condensate and cause water hammer in steam line.
43
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
44
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
45
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
46
The dust collection efficiency of a cyclone separator
A. decreases with increase in gas flow rate.
B. is inversely proportional to the mass of the dust particle.
C. is directly proportional to the radius of the dust particle path.
D. none of these.
none of these
47
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
48
Which of the following types of reactors is the safest from operation point of view ?
A vapor phase reactor.
49
In a bag filter, the pressure drop increases directly as the
density of the gas and inversely as viscosity of the gas.
50
The LMTD correction factor (FT) is applied in __________ heat exchangers.
all multipass
51
Movement of pipeline caused by thermal expansion is taken care by providing
A. expansion joint.
B. changes in its direction.
C. change in the shape of pipeline.
D. all (a), (b) and (c).
all of the above
52
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.
53
In the design of a paddle agitator, the ratio of paddle dia/tank dia is normally taken as
0.8
54
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
55
Hole diameter of the seive trays in the distillation column ranges from __________ mm.
3 to 12.5
56
Factor of safety (i.e., overdesign factor) in heat transfer equipments is about __________ percent more than the actual/theoretical design factor.
15-20
57
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.
58
The minimum shell thickness for tank ≤ 15 metres diameter is limited to __________ mm, for reasons of elastic stability.
5
59
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.
60
Brass valves are usually made for pipe sizes __________ inches.
≤2
61
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
62
In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement
results in higher shell side pressure drop.
63
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.
64
The necessary wall thickness for a metallic storage vessel is a function of the
A. ultimate tensile strength (or yield point) of the material and operating temperature.
B. operating pressure and welding/joint efficiency.
C. diameter of the vessel.
D. all (a); (b) and (c).
all
65
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
66
Pick out the wrong statement
In a flanged and standard dished head, the crown radius is ≤ shell outside diameter.
In a flanged and shallow dished head, the crown radius is > shell outside diameter.
Flat head covers are most suitable for larger vessels operating at very high pressure.
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.
67
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.
68
Weep holes provided in the plates of a distillation column
A. facilitate draining out liquid from a tray when the unit is not in operation.
B. are normally located near the overflow weir so that any delivery of liquid during operation follows approximately the same path as the overflow fluid.
C. must be large enough (usually 1/4" to 5/8" dia) to prevent plugging but should not deliver excessive amount of fluid during operation.
D. all (a), (b) and (c).
all
69
Steam is preferred to be used as a heating medium in heat exchangers, because of its
high latent heat.
70
__________ shapedroof is the most commonly used roof for cylinderical storage tanks.
conical
71
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 .
72
Value of Peclet number = ∞, is the representative of
plug flow
73
In most of the shell and tube heat exchangers, the tube pitch is generally __________ the tube diameter.
1.25-1.50
74
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
75
1.2 to 3.8 cms is the value of the
A. downcomer liquid seal in case of a balanced tray design.
B. static submergence in case of a bubble cap tray for column operating under pressure (≥ 1 atm.).
C. skirt clearance for bubble caps.
D. all (a), (b) and (c).
all
76
Accidents in chemical plants are mostly due to
faulty operating procedures.
77
For identical operating conditions, the pressure drop over __________ tray is the highest out of the following.
bubble cap
78
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
79
__________ is the determining factor for the number of bubble caps to be used per tray.
Permissible slot velocity
80
Pick out the wrong statement about distillation operation
Distillation under vacuum is a substitute for steam distillation.
In differential (simple) distillation, the vapour is removed as soon as it is formed without appreciable condensation.
In flash (equilibrium) distillation, a definite fraction of liquid is vaporised in such a way that the evolved vapour & residual liquids are in equilibrium with each other.
Flash distillation, differential distillation & steam distillation are all continuous distillation processes.
Flash distillation, differential distillation & steam distillation are all continuous distillation processes.
81
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
82
Which of the following is the best tube material from thermal conductivity point of view alone?
copper
83
Normal screwed fittings are used for pipes upto a diameter of __________ inches.
3
84
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".
85
Diameter of the seive tray column is determined by the
upper limit of the vapour velocity.
86
For a given fluid, as the pipe diameter increases, the pumping cost
decreases
87
Maximum acceptable total liquid gradient over a tray is about __________ mm.
12.5
88
In case of a 'thin' pressure vessel, the ratio of its diameter to wall thickness is
> 10
89
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.
90
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.
91
Fresh water carrying pipelines in chemical industries are coloured with __________ color.
sea green
92
Which of the following material is seldom used for pressure vessel construction ?
Rimmed steel
93
The ratio of shear stress to shear strain is called
shear modulus
94
25 per cent cut segmental baffle means that the baffle
height is 75% of the I.D. of the shell.
95
Liquid/petroleum fuel storage tanks are built underground (as in case of petrol pumps), when the storage capacity is less than __________ kilolitres.
45
96
Le/D for fully open globe value may be around
300
97
Lug support is
A. the most suitable for thick vertical vessel.
B. same as bracket support.
C. provided usually for vessels of much smaller height than skirt supported vessels.
D. all (a), (b) and (c).
all
98
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.
99
With increase in the number of shell passes, the value of FT
increases
100
Holes of a sieve tray are arranged in triangular pitch of __________ times the hole diameter.
2.5-5
101
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
102
The stress developed in a material without any permanent set is called the
elastic limit
103
In a shell and tube heat exchanger, the 'tube pitch' is defined as the
shortest centre to centre distance between adjacent tubes.
104
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.
105
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
106
The value of fouling factor depends upon the
A. characteristic of process fluid.
B. velocity of process fluid containing suspended solids.
C. suspended solids in the fluid.
D. all (a), (b) and (c).
all
107
In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about __________ cms.
10
108
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
109
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
110
Where does the maximum tensile strength occur in a thick cylindrical vessel subjected to internal pressure ?
At the inner surface.
111
It is not desirable to design a heat exchanger for LMTD correction factor, FT, of less than
0.8
112
A rivetted joint does not fail by __________ of rivets.
none
113
Bracket supports are the most suitable for supporting __________ vessels.
thick walled vertical
114
In a multipass shell and tube heat exchanger, the shell side cross flow area does not depend upon
none of these
115
Two iron pipes of the same nominal diameter but different schedule numbers will have the same
inside diameter
116
Steam side heat transfer co-efficient for design consideration under ordinary condition can be assumed to be about __________ kcal/hr.m2.°C.
7500
117
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
118
In chemical process equipments, the conical bottom heads used, usually has an apex angle of
60 degrees
119
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
120
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
121
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.
122
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
123
__________ tray arrangement is recommended for distillation column having diameter upto 4 ft.
cross flow
124
What is the value of 'q' for saturated liquid feed to a distillation column ?
1
125
In perforated plate towers, the
A. hole sizes may be around 1/8" or 3/16".
B. total hole area may be around 6 to 15% of tower cross-sectional area.
C. pressure drop is less compared is similar bubble cap towers.
D. all (a), (b) and (c).
all
126
The main purpose of providing stepping on the trays is to
facilitate handling of large flow rate of liquid.
127
The operating pressure drop range in a bag filter is about __________ mm water gauge.
50-150
128
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
129
For laminar flow (NRe < 2100) in steel pipe, the optimum inside pipe diameter is given by
Di, opt = 3 Q0.36 ρ0.18
130
Pick out the correct statement.
When highly corrosive fluids are to be handled, the plate towers prove to be cheaper and easier to construct than packed tower.
Packed towers are generally preferred over plate towers, if the liquids have a foaming tendency.
The pressure drop through the packed towers is generally more than the pressure drop through plate towers designed for same duty.
none of these.
Packed towers are generally preferred over plate towers, if the liquids have a foaming tendency.
131
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.
The tube bundle is suspended on bracket.
There is no central downtake.
Downtake is formed by the annular space between the bundle and the shell.
It is used for high viscosity liquor having large rate of scaling.
132
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
133
Speed of the drum of the rotary vacuum filter normally ranges from __________ rpm.
0.1-2
134
A stuffing box is used for
prevention of fluid leakage around moving parts.
135
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 = G2
136
Pick out the wrong statement.
In an agitated vertical cylinderical reaction vessel, the
dished bottom vessel has very high power consumption.
137
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
138
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 = 1.004G0.37
139
In the agitators, the power required will be changed with the increase of diameter of agitator (D) as
D^5
140
Apex angle of conical heads used in the bottom heads of chemical process equipments is usually
60°
141
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 (dimensionless) for 45° elbow and 180° close return bends would be respectively around
45 and 75
142
A pressure vessel is said to be made of 'thick' shell, if the ratio of its diameter to wall thickness is
10
143
Tube side heat transfer co-efficient for turbulent flow of liquid through tubes is proportional to
G^0.8
144
Circumferential (hoop) stress in a thin cylindrical vessel under internal pressure is __________ the longitudinal stress.
twice
145
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
146
Which of the following factors determine the amount of entrainment in a distillation column ?
A. Plate spacing.
B. Depth of liquid above the bubble cap slots.
C. Vapour velocity in the volume between the plates.
D. All (a), (b) and (c).
all
147
The absorption factor is defined as (where, S1 = slope of the equilibrium curve, S2 = slope of the operating line)
S1/S2
148
In shell and tube heat exchangers, straight tie rods are used to
hold baffle in space.
149
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.)
ZHp/L
150
In case of design of a shell and tube heat exchanger,
A. minimum cleaning lane of 6.5 mm is provided, when tubes are on a square pitch.
B. minimum tube sheet thickness (in which tubes are fixed) is equal to the O.D. of the tube upto 15 mm tube diameter; and for > 15 mm tube diameter, tube sheet thickness is smaller than tube diameter.
C. O.D. of the tube is 6 to 40 mm while the tube lengths used are 0.5, 2.5, 3.0, 4.0, 5.0, 6 metres.
D. all (a), (b) & (c).
all
151
In a cylinderical vessel subjected to internal pressure, the longitudinal stress σL and the circumferential stress, σn are related by
σh = 2 σL
152
Nominal size of a pipe is an indication of its __________ diameter.
approximate
153
Excessive liquid gradient on a tray may result in the
A. maldistribution of gas.
B. back trapping.
C. gas blowing beneath cap skit.
D. all (a), (b) and (c).
all
154
The ratio of tube length to shell diameter in case of liquid shell and tube heat exchanger ranges from
4 to 8
155
In a double pipe concentric heat exchanger, the equivalent diameter of annulus for heat transfer would be (where, D1 and D2 are I.D. of inner and outer pipes)
D^2 -D1^2/D1^2
156
What is the slope of the operating line in the stripping section of a distillation column ?
>1
157
__________ shaped roof is most commonly used for cylindrical tanks.
Cone
158
In a thin cylindrical shell, the hoop stress is __________ stress.
circumferential tensile
159
Commercial packed scrubbers are normally designed for a pressure drop range of __________ mm water coloumn per metre of packed height.
17-34
160
The retention time of material in a rotary dryer depends upon its
a. rpm
b. slope & length
c. flights arrangement
d. all (a), (b) and (c)
all
161
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.
a. molal flow rate of vapour
b. vapour molecular weight
c. pressure and temperature
d. all (a), (b) and (c)
all
162
Rotary driers are most economically designed for the number of heat transfer units (HTU) from
1.5 to 2.5
163
The difficulty of liquid distribution in packed towers is accentuated, when the ratio of tower diameter to packing diameter is
< 7
164
An increase in the liquid resistance to interphase mass transfer and a resultant reduction in plate efficiency is caused by
A. an increase in liquid viscosity.
B. an increase in relatived volatility for rectification columns.
C. decrease in gas solubility for absorbers.
D. all (a), (b) and (c).
all
165
In the design of a bag filter, the gas temperature is an important consideration, as it affects the
A. gas density
B. gas viscosity
C. fibre selection
D. all (a), (b) & (c)
all
166
With increase in temperature drop (in a shell and tube heat exchanger), the LMTD correction factor, FT
decreases very rapidly
167
The normal range of velocity of steam in pipes is __________ m/sec.
80-100
168
__________ dished head is the strongest of all.
Hemispherical
169
Pick out the correct statement.
It is preferred to use a vertical condenser for condensation of vapor from a distillation column without sub-cooling
Draining of residual liquid on tray during shut down of distillation column is facilitated by weep holes.
Random packing a packed tower offers the advantage of lower pressure drop and higher throughput of fluids as compared to regular/stacked packing.
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.
170
"A claming section" before the liquid flows into the downcomer is privided to
permit release of entrained vapour in the liquid.
171
The units of Young's modulus of elasticity and __________ are the same.
stress
172
In the design of a shell and tube heat exchanger, the corrosion allowance
all
173
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.
174
Hazards associated with the relief valve leakage for extremely hazardous material storage can be taken care of by providing
rupture diaphragm
175
Minimum baffle spacing recommended in a shell and tube heat exchanger is equal to
5 cms
176
__________ liquor is best handled in a long tube vertical evaporator.
Foamy
177
Theoretically calculated diameter of the stripping section of the continuous rectification column is __________ that of the enriching section.
more than
178
Hold up of material in a operating rotary drier is in the range of
0.05 to 0.15
179
A binary liquid azeotropic mixture has boiling point higher than either of the components, when it shows __________ deviation from Raoult's Law.
negative
180
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
181
Flanges are connected to pipes by
all
182
The ratio of down take area to cross-sectional area of the tube, for calendria type evaporator ranges from
0.5 to 1
183
Shortest distance between two tubes is
called tube clearance.
