Process Equipment and Plant Design Part 2 Flashcards
__________ tower is the most suitable gas-liquid contacting device involving highly corrosive fluids.
Sieve plate
Packed
Bubble cap plate
None of these
Packed
At equal mass velocities, the values of film co-efficients for gases as compared to that for liquids are generally.
higher
lower
same
unpredictable
lower
The ratio of the largest load in a test to the original cross-sectional area of the test specimen is called the __________ stress.
yield point
breaking
ultimate
none of these
ultimate
A ‘rupture disc’ is provided in chemical equipments as an accessory meant for
relieving excess pressure.
creating turbulence.
enhancing mixing rate.
avoiding vortex formation.
relieving excess pressure.
In a vertical short tube evaporator (Calendria type), the
tube dia of 2.5-7.5 cms, tube length of 75-200 cms and cylinderical drum dia of 1-6 metres are normally used.
area of central downtake is equal to 40 to 100% of total cross-sectional area of the surrounding tube.
liquor is inside the tube while the steam is outside the tube.
all (a), (b) & (c).
all (a), (b) & (c).
In a shell and tube heat exchanger, the shortest centre to centre distance between the adjacent tubes is
called tube pitch.
called tube clearance.
always less than the diameter of the tube.
none of these.
called tube pitch.
Remember:
tube pitch - shortest center to center distance
tube clearance - shortest distance
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.
reduction of discontinuity in shape at the junction.
making the joint leak proof.
none of these.
preventing the local overstressing of the shell around the opening.
any shell opening… preventing loval overstressing…
Minimum tube pitch recommended for shell and tube heat exchangers is about __________ times the outside diameter of the tube.
1.25
1.75
2.5
3.5
1.25
1.25x OD minimum tube pitch
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
5-7.5
10-12.5
15-20
2.5-3.0
Slope of countercurrent flow rotary drier is in the range of __________ meter/metre.
0 to 0.08
0 to 0.8
0 to 1.5
0 to 2.2
0 to 0.08
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/5th
l/15th
l/30th
l/50th
l/15th
The minimum baffle height should be
equal to the impeller diameter.
twice the impeller diameter.
twice the tank diameter.
3/4 of the tank height.
twice the impeller diameter.
For turbulent flow (NRe > 2100) of low viscosity fluid (mu > 20cp) in steel pipes, the optimum inside pipe diameter is given by(where, Q = fluid flow rate, ft^3/sec.rho = fluid density, lb/ft^3 mu = fluid viscosity, centipoise Di = optimum inside pipe diameter, inches)
Di, opt = 3.9 Q^0.45 (rho)^0.13
Di, opt = 3.9 Q^0.45 (mu)^0.95
Di, opt = 4.7 Q^0.36 (mu)^3.2 (rho)^0.13
Di, opt = 3 Q^0.36 (mu)^0.88
Di, opt = 3.9 Q^0.45 (rho)^0.13
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
0.5 d
d
1.5 d
2.5 d
1.5 d
1.5d avoid tearing off
The normal range of velocity of water in pipes is __________ m/sec.
0.1-0.5
1-2
10-50
15-30
1-2
1-2 m/s velocity of water in pipes
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 ?
Segmental baffle
Flat plate extending across the wall
Disk type baffle
Helical type baffle
Flat plate extending across the wall
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
only if the opening is on spherical vessel.
only if the opening is on a vertical cylinderical vessel.
only if the opening is on a horizontal cylinderical vessel.
irrespective of the shape of the vessel.
irrespective of the shape of the vessel.
In a __________ rivetted joint, the number of rivets decreases from the innermost row to the outermost row.
chain
diamond
zig-zag
none of these
diamond
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.
1 to 5
10 to 20
30 to 40
40 to 50
10 to 20
Heat transfer co-efficient for a horizontal condenser as compared to a vertical condenser operating under similar conditions is
same
less
about 3 times
about 0.33 times
about 3 times
Pick out the wrong statement pertaining to the design of the distillation column.
Generally, a skirt clerance of 0.5” to 1.5’ is recommended to prevent plugging of the slots by residue build up.
The purpose of the slot is to disperse the gas into the liquid in the form of small bubbles.
If sufficient slot area is not provided, the gas may pass through the skirt clearance.
none of these.
none of these.
The longitudinal stress induced in a thin walled cylinderical vessel under internal pressure is
pd/2t
pd/4t
pd/t
pd/8t
pd/4t
The buckling tendency of compression members is always in the direction of the
least radius of gyration.
axis of the load.
perpendicular to the axis of the load.
none of these.
least radius of gyration.
In case of plain carbon steel, butt welded joints are used for shell plate thickness =< __________ cms.
1.2
0.5
3.8
6.8
3.8
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.
2
1/2
4
1/4
4
Hoop (circumferential) stress induced in a thin walled ‘Horton Sphere’ used for the storage of liquid ammonia under pressure is
pD/2t
pD/4t
pD/3t
pD/6t
pD/2t
remember: hoop horton pD/2t
When one of the fluids is highly corrosive and has fouling tendency, it should
preferably flow inside the tube for its easier internal cleaning.
perferably flow outside the tube.
flow at a very slow velocity.
flow outside the tube, when the flow is counter-current and inside the tube when the flow is co-current.
preferably flow inside the tube for its easier internal cleaning.
The ratio, propeller agitator dia/tank dia is normally taken as
0.15-030
0.5-0.65
0.75-0.85
0.60-0.90
0.15-030
A/an __________ is used for changing the direction of a pipeline.
elbow
union
flange
disc compensator
elbow
Maximum plate efficiency is achieved in case of __________ flow.
split
cross
cascade
reverse
cross
The LMTD correction factor (FT) is defined as the
ratio of true temperature difference to the LMTD.
ratio of LMTD to the true temperature difference.
differenced of true temperature difference and the LMTD.
geometric mean of the true temperature difference and the LMTD.
ratio of true temperature difference to the LMTD.
remembe: true to LMTD
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.
equal to
half
one fourth
three fourth
one fourth
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
0.50
0.75
1.25
0.25
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
3.5-5.5
7.5-10.0
10-15
1.5-2.5
Value of Peclet number = 0, is the representative of
laminar flow.
complete back mixing.
plug flow.
eddy diffusivity = 0.
complete back mixing.
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
0.01
0.3
0.75
0.95
0.3
Removable connection of tubes to tube sheet is called
ferrule
socket
nipple
saddle
ferrule
Typical static submergence for bubble cap plate column operating at atmospheric pressure may be around
2.5”
0.5”
5”
50% of the plate spacing
0.5”
The length of straight rectangular weir used on cross-flow trays is generally __________ the column diameter.
0.6-0.8 times
equal to
twice
2 ft irrespective of (for column > 3 ft diameter)
0.6-0.8 times
Le/D for couplings and unions would be
60
200
350
negligible
negligible
What is the slope of the operating line in the rectifying section of a distillation coloumn ?
0
infinite
> 1
<1
<1
rectifying <1
stripping >1
Stage efficiency for packed tower varies with the
type & size of packing.
fluid rates and fluid properties.
operating pressure and column diameter.
all (a), (b) and (c).
all (a), (b) and (c).
The minimum plate spacing in most of the pertroleum refinery distillation columns (of dia > 3 ft) is normally __________ inches.
6
12
18
34
18
Joint efficiency (J) for a seamless pipe is
1
0.85
1.2
< 0.5
1
seamless = 1 always
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.
plate spacing.
diameter of the column.
all (a), (b) and (c).
allowable gas velocity through the slots.
The shell side pressure drop in a shell and tube heat exchanger is maximum for __________ baffle.
disk and ring
segmental
orifice
independent of the type of
orifice
The function of manholes provided in the shell of a distillation column is to
keep a check on the liquid gradient over the plate by direct visual observation.
give access to the individual trays for cleaning, maintenance and installation.
guard against foaming & entrainment by dumping antifoaming agent through it.
all (a), (b) and (c).
give access to the individual trays for cleaning, maintenance and installation.
Back-trapping in a distillation column results due to
low gas velocity.
high gas velocity.
excessive liquid gradient over the tray.
low reflux ratio.
excessive liquid gradient over the tray.
excessive liq. grad. back-trapping
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
0.9
1.0
(0.8)^0.5
0.8
The ideal size of round bubble caps to be used in industrial distillation column having a diameter of 3-6 metres is __________ cms.
5
15
7.5
50
15
15-3-6 15 cm 3-6 m round bubble caps
Lap joints are preferred for plates having thickness __________ mm.
< 12.5
> 3
> 5
5-10
> 3
In a distillation column, minimum clearance to be maintained betweeen the overflow weir and the last row of the bubble caps is __________ cms.
2.5
7.5
15
20
7.5
7.5 cms overflow weir and last row distance
Which of the following lengths of heat exchanger tubes are normally not used in practice ?
2.5 metres
6 metres
10 metres
0.5 metre
10 metres
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
1000
3000
5000
10000
10000
Equivalent diameter for heat transfer calculation for a duct of square cross-section having each side as ‘d’ will be
d
sqrt(d)
sqrt(2pid)
sqrt(2d)
d
A cylindrical storage tank can have a self supported conical roof,
if its diameter is less than 15-20metres.
if its diameter is more than 50 meters.
if the thickness of the roof is more than that of the cylindrical shell.
irrespective of its diameter.
if its diameter is less than 15-20metres.
For high pressure process equipments/vessels, the connected nozzle should be
welded
screwed
flanged
brazed
flanged
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).
feed is not at its bubble point.
number of equilibrium stages in only stripping section is to be calculated.
number of equilibrium stages required is likely to be very small.
relative volatility is close to one (e.g., separation of close boiling isomers).
Column support for the roof of cylindrical storage tank must be provided for
small diameter tanks.
large diameter tanks.
small diameter tall tanks.
all tanks irrespective of their heights and diameters.
large diameter tanks.
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 ?
hemispherical
ellipsoidal (2 : 1)
conical
flat plate
ellipsoidal (2 : 1)
In inclined long tube vertical evaporators, the tubes are inclined at an angle of
15 degrees
90 degrees
45 degrees
60 degrees
45 degrees
In a continuous distillation column, the optimum reflux ratio ranges from __________ times the minimum reflux ratio.
1.1 to 1.5
1.6 to 2
2.2 to 2.6
2.7 to 3
1.1 to 1.5
The wall thickness for a large high pressure pipeline is determined by the consideration of the
axial tensile stress in the pipe.
forces exerted by static and dynamic action at bends.
circumferential pipewall tension.
temperature stresses.
circumferential pipewall tension.
In the case of a shell and tube heat exchanger, the logarithmic mean temperature difference
is always less than arithmetic average value.
is always more than arithmetic mean value and the geometric mean value.
is always less than arithmetic mean value, but more than geometric mean value.
may be either more or less than geometric mean and arithmetic mean value depending upon whether the flow of stream is co-current or counter-current.
is always less than arithmetic average value.
Skirt support is the most suitable for supporting __________ vessels.
small horizontal
large horizontal
tall vertical
thick walled
tall vertical
Baffles may be eliminated for
low viscosity liquids (< 200 poise).
high viscosity liquids (> 600 poise).
large diameter tanks.
none of these.
high viscosity liquids (> 600 poise).
Generally, as the length of the liquid path on a tray is increased beyond 5 ft, the overall column efficiency
increases
decreases
remains same
may increase or decrease depending upon the plate spacing
increases
In packed absorption tower, onset of flooding usually occurs at a pressure drop of about __________ mm of water column per metre height of packing.
25-50
50-75
200-250
750-1000
50-75
For pipe flows, head is proportional to __________ at constant capacity (where D = pipe diameter ).
1/D
1/D^2
1/D^5
D^2
1/D^5
Friction factor for turbulent flow in a new pipe is given by (N = Reynold’s number)
f = 16/N
f = 0.04/(N^0.16)
f = 0.22 N^0.5
f = 25/N
f = 0.04/(N^0.16)
The minimum tray spacing in distillation column of diameter less than 3 ft is normally __________ inches.
6
18
24
34
6
Oxygen carrying pipelines in chemical industries are coloured with __________ colour.
yellow
black
blue
red
blue
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
0.4-0.6
0.35-0.75
0.1-0.2
0.55-0.85
0.1-0.2
Pick out the wrong statement about the design of seive plate column and the bubble cap column.
The downcomer design and the residence time in the downcomer is almost same for seive plate and bubble cap columns.
Weir length for a bubble cap plate is the same as that for the seive plate.
Weir height for a bubble cap plate column is the same as that for a seive plate column.
Weir height in case of a bubble cap plate ranges from 50 to 150 mm and is higher than the seive plate.
Weir height for a bubble cap plate column is the same as that for a seive plate column.
Maximum size of the raschig rings used in a packed tower is about __________ of the coloumn diameter.
1/10th
1/20th
1/30th
1/50th
1/30th
Longitundinal stress induced in a thin walled cylindrical storage vessel is
pD/2t
pD/4t
pD/3t
pD/6t
pD/4t
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.
shear
tensile
compressive
thermal
thermal
The safe distance of habitation from a hazardous chemical plant (TLV of its product < 1000 ppm) should be about __________ kms.
1
5
15
25
25
Pick out the wrong statement pertaining to a shell and tube heat exchanger.
The minimum value of baffle spacing is 50 mm.
The maximum value of baffle spacing is equal to the I.D. of the shell.
The maximum unsupported tube span is generally about 75 times tube diameter, but is reduced to about 60 times for aluminium, copper & alloys of these.
Disk and doughnut baffle is the most commonly used baffle.
Disk and doughnut baffle is the most commonly used baffle.
Maximum allowable vapour velocity in a bubble cap tower is determined by the
entrainment considerations.
vapour density.
diameter of the column.
none of these.
entrainment considerations.
Normally, the plate thickness of the bottoms and roofs of vertically cylindrical storage vessels as compared to that of the cylindrical shell is
more
less
same
more or less depending upon the pressure & temperature inside the vessel and the nature of the fluid contained therein.
less
The practical representative values of HETP for a number of commercial operations lies within a range of __________ metre.
0.1-0.2
0.2-0.5
0.4-0.9
1.2-1.5
0.4-0.9
Of the pressure vessels, with same thickness but different diameters, which one withstands higher pressure ?
Larger dia vessel.
Smaller dia vessel.
Larger dia long vessel.
Strength of the vessel is same irrespective of the diameter.
Smaller dia vessel.
Reflux ratio variation in a distillation column is between
zero and infinity
zero and one
minimum and infinity
none of these
minimum and infinity
Width and depth of grooves in the tube sheet holes normally are __________ inch respectively.
1/8 and 1/64
1/64 and 1/8
1/2 and 8
1/2 and 5
1/8 and 1/64
In condenser, the cooling water is passed in the tube side in a pass arrangement, because
it reduces heat transfer area.
more thinner tubes can be used.
pressure drop is reduced.
it makes condenser compact.
it reduces heat transfer area.
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
1/5-1/10th
1/20-1/30th
1/2 to 1/4th
1/10-1/15th
Height of the flights in the rotary drier is in the range of
0.08 to 0.12 d
0.02 to 0.05 d
0.2 to 0.5 d
0.5 to 0.6 d
0.08 to 0.12 d
Vapor velocity in a distillation column for non-foaming mixture is in the range of __________ times the flooding velocity.
0.1 to 0.3
0.6 to 0.7
0.85 to 0.95
1.5 to 2
0.6 to 0.7
Cylindrical storage tanks used for the storage of volatile liquids (e.g., naphtha) have __________ roofs.
conical
flat
floating
fixed
floating
Pick out the wrong statement.
Plate efficiency increases with increase in superficial vapour velocity till entrainment limit.
Increase in depth of the liquid about the slots increases the plate efficiency, particularly if the liquid depth is < 1”.
Too small a plate spacing can cause a low efficiency, if the vapour velocity is greater than the allowable value.
none of these.
none of these.
Pick out the wrong statement.
In practical operation, distillation towers having diameter 3-6 metres equipped with bubble cap (round) size of 15 cms are used.
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.
In a seive tray, the minimum hole diameter is equal to the tray thickness.
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.
In the downcomer of a distillation column, the minimum recommended residence time is about __________ seconds.
2.5
5
12.5
17.5
5
For identical situation, condensing film coefficient in case of a horizontal condenser is almost __________ the value expected in case of vertical condenser.
half
twice
thrice
five times
thrice
Diameter of rivet hole (d, mm) and the plate thickness (t, mm) are related by Unwin’s formula as
d = 1.1 t
d = 1.6 sqrt(t)
d = 1.5 t
d = 3 sqrt(t)
d = 1.6 sqrt(t)
A binary liquid azeotropic mixture has boiling point lower than either of the components, when it shows __________ deviation from Raoult’s Law.
positive
negative
no
none of these
positive
negative “higher”
positive “lower”
In which of the following evaporators, steam is fed inside the tube while the liquor is outside the tube ?
Long tube vertical evaporator
Short tube vertical evaporator
Horizontal tube evaporator
None of these
Horizontal tube evaporator
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
2^0.8
2^0.2
none of these
2^0.8
In a multipass shell and tube heat exchanger, the baffles on shell side is primarily provided for
reducing scale deposition.
increasing pressure drop.
fixing the tubes.
creating turbulence.
creating turbulence.
For turbine agitator, the impeller diameter is about
0.3 to 0.5 d
0.1 to 0.2 d
0.65 to 0.85 d
0.95 d
0.3 to 0.5 d
In a shell and tube heat exchanger having triangular pitch, the shell side equivalent diameter is given by
4[0.86(p^2) - pi(d^2)/4]/(pid)
[(p^2) - pi(d^2)/4]/(pid)
4[0.86(p^2) - pi(d^2)]/(pid)
(4(p^2) + pi(d^2)/4]/(pid)
4[0.86(p^2) - pi(d^2)/4]/(pid)
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 1.8
decrease by 2^2
increase by 2^1.6
none of these
increase by 2^1.6
Pick out the wrong statement pertaining to the design of a long tube vertical evaporator.
Tube dia is 3-6 cms, while tube length in 3-6 metres.
Steam is fed to the shell, whereas the liquor is filled inside the tube.
Liquor level is maintained at l/3rd to 1/2 of the height of the tube.
none of these.
none of these.
Which of the following is the most common type of baffle used in industrial shell and tube heat exchanger ?
75% cut segmental baffle.
25% cut segmental baffle.
Orifice baffle.
Disk and doughnut baffle.
25% cut segmental baffle.
What is the minimum recommended ligament for square pitch arrangement in case of heat exchangers ?
6.5 cms
6.5 mm
Equal to tube I.D
Equal to tube O.D
6.5 mm
Pick out the correct statement
Centre to centre distance between two consecutives rivets in a row is called the pitch.
A rivetted joint made in overlapping plates is called butt joint.
Hole size drilled in rivetted plates is less than the actual size of the rivet.
none of these.
Centre to centre distance between two consecutives rivets in a row is called the pitch.
Safety valves are provided in chemical equipments to guard against excessive
temperature
pressure/pressure fluctuation
turbulence
noise
pressure/pressure fluctuation
The equivalent diameter for pressure drop is __________ that for heat transfer.
smaller than
greater than
equal to
not related with
not related with
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
downcomer liquid seal
static submergence
skirt clearance
none of these
static submergence
Liquid gradient over the tray results due to the
resistance offered to flow of liquids by caps & risers and the flow of gas.
low gas velocity.
large plate spacing.
large reflux ratio.
resistance offered to flow of liquids by caps & risers and the flow of gas.
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 residence time of shell side fluid.
To provide support to the tube bundle.
To reduce the induced vibration in the tubes.
To increase the tube side heat transfer co-efficient by inducing turbulence.
To increase the tube side heat transfer co-efficient by inducing turbulence.
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.
45
60
80
95
80
The approximate liquid depth in an agitation tank is equal to (where, d = tank diameter)
0.5 d
0.75 d
d
2 d
d
Baffle width is normally taken as __________ times the tank diameter.
0.1-0.12
0.4-0.5
0.45-0.6
0.2-0.45
0.1-0.12
A cylinderical pressure vessel of volume 6 ?m3 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
5 mm
6 mm
8 mm
10 mm
10 mm
Which of the following packing materials provides for maximum mass transfer ?
Lessig rings.
Raschig rings.
Cross-partition rings.
All give the same value.
Cross-partition rings.
__________ of water makes it a widely used coolant in heat exchangers.
Low corrosiveness
Low dirt factor
High specific heat
Low viscosity
High specific heat
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
A/P
4 P/A
sqrt(A)
4 A/P
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.
containing suspended solids flows at high velocity.
is highly viscous.
is of high specific gravity.
containing suspended solids flows at low velocity.
Lug support is meant for supporting __________ vessels.
large horizontal cylindrical
tall but empty
small
thick walled tall
small
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.
CO2
SO2
NH3
none of these
NH3
Which tube arrangement in a heat exchanger would facilitate highest heat transfer rate ?
Triangular pitch.
Square pitch.
Diagonal square pitch.
Heat transfer rate is independent of tube arrangement.
Triangular pitch.
In case of 1.5” heat exchanger tubes, the inside flow area __________ with decrease in BWG.
increases
decreases
remains same
none of these
decreases
Cylindrical pressure vessels in horizontal condition is generally supported on a __________ support.
lug
skirt
saddle
guy wire
saddle
Pressure drop per tray in the atmospheric distillation column is about __________ psi.
0.01 - 0.5
0.07 - 0.12
0.5 - 1.0
1 - 3
0.07 - 0.12
Welded joint efficiency in the design of chemical process equipment is taken as
0.55
0.75
0.85
0.95
0.85
The thickness of segmental baffles (25 -35% cut truncated plates usually) is generally __________ the tube wall thickness.
equal to
twice
four times
half
twice
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
2
3
3.5
1
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.
about 9
considerably more than 9
considerably less than 9
about 3
considerably more than 9
The ratio of linear stress to linear strain is termed as the
modulus of elasticity
modulus of rigidity
bulk modulus
none of these
modulus of elasticity
__________ head is the most economical for cylindrical vessels designed for operating at high pressure (> 15 atm.).
Hemispherical
Dished
Ellipsoidal
Conical
Ellipsoidal
Bubble cap plate column is
a finite stage contactor.
used only for distillation, not for absorption.
a differential stage contactor.
a continuous contactor.
a finite stage contactor.
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.
0.5 to 1.5
2.5 to 4.0
5 to 10
10 to 15
2.5 to 4.0
Pick out the wrong statement.
Rivetting provides a permanent fastening method.
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’.
Shank diameter of the rivets should be less than the size of the hole drilled in the plate for rivetting.
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’.
The force due to wind load acting on a tall vessel depends upon its
shape.
outside diameter.
height.
all (a), (b) & (c).
all (a), (b) & (c).
Bubble cap diameter used for the distillation column having diameter ranging from 1.5 to 4.5 metres is about __________ mm.
10
50
100
150
100
Power required for agitation depends upon the
height & properties of the liquid.
agitator type & speed of agitation.
size of agitator & the tank.
all (a), (b) and (c).
all (a), (b) and (c).
Tube height in a calendria type evaporator is normally less than __________ metres.
1
2
3.5
5.5
2
Pick out the wrong statement.
Lug supports are less expensive than other type of supports.
A pipe is differentiated from a tube by the fact that a pipe has a greater wall thickness compared to the tube.
A reducer is used to change the direction of a pipe in a straight run.
The method of fixing tubes to a tube sheet by expanding is called ‘tube rolling’.
A reducer is used to change the direction of a pipe in a straight run.
For a 25 mm hole drilled in plates to be rivetted, the shank diameter of the rivet should be __________ mm.
25
23
26
27
23
In a shell and tube heat exchanger having square pitch, the shell side equivalent diameter is given by (where, P = pitch, d = outside diameter of the tube)
4[P^2 - (pid^2)/4]/(pid)
[P^2 - (rd^2)/4]/(rd)
(4P^2)/(pid)
(pid)/(4P^2)
4[P^2 - (pid^2)/4]/(pid)
Optimum economic pipe diameter for fluid flow is determined by the
viscosity of the fluid.
density of the fluid.
total cost considerations (pumping cost plus fixed cost of the pipe).
none of these.
total cost considerations (pumping cost plus fixed cost of the pipe).
Pressure differential maintained across a continuous rotary vacuum filter is in the range of __________ mm Hg column.
50 to 100
100 to 150
250 to 500
600 to 700
250 to 500
Vertical storage vessels are never supported by __________ support.
bracket
saddle
skirt
lug
saddle
In a double pipe (concentric) heat exchanger, the hydraulic radius for heat transfer (for a fluid flowing through the annulus) would be
same as that for fluid flow.
less than that for fluid flow.
more than that for fluid flow.
D2 - D1 (D1 and D2 are I.D. of inner and outer pipes respectively).
more than that for fluid flow.
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, sigma = yield strength and E = modulus of elasticity)
E
sigma
sigma/E
E/sigma
sigma/E
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
five
ten
twenty
two
What is the slope of the feed line, if the feed to a distillation column is a saturated liquid ?
0
infinity
> 1
< 1
infinity
Filtration rate is affected by the
pressure drop across the cake & filter medium.
cake & filter medium resistance.
area of filtering surface & the viscosity of filtrate.
all (a), (b) and (c).
all (a), (b) and (c).
Liquid gradient over a tray can be minimised by
providing a higher skirt clearance or a higher weir.
decreasing the number of rows of caps through which the liquid flows or by decreasing the velocity of liquid flow past the caps or by reducing the distance along the tray through which the liquid must flow.
using split flow, radial flow or cascade flow for column diameter large than 4 ft.
all (a), (b) and (c).
all (a), (b) and (c).
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
are easier to clean.
are less prone to fouling.
can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less.
none of these.
can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less.
Le/D for 90-degree elbow (medium radius) and 90-degree square elbow would be respectively around
25 and 60
3 and 5
100 and 250
250 and 600
25 and 60
__________ heat exchanger is also known as ‘hair pin type’ exchanger,
Double pipe
Finned
Plate type
Regenerative
Double pipe
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
1
<0
> 1
0
In hydrostatic testing of welded pipe (for leakage, strength etc.) the ratio of minimum hydrostatic test pressure to internal design pressure is around
0.5
1.5
2.5
3.5
1.5
Frame thickness in the plate and frame filter press is normally in the range of __________ inches.
0.25 to 4
0.25 to 8
1 to 5
1 to 12
0.25 to 8
Cylinderical shell thickness of rotary drier is generally __________ mm.
2-3
18-22
6-8
12-15
6-8
The ratio of lateral strain to linear strain is termed as the
Poisson’s ratio
bulk modulus
modulus of elasticity
shear modulus
Poisson’s ratio
The distance between the centre of a rivet hole to the nearest edge of the plate is called
pitch
margin
back pitch
none of these
margin
Mc Cable Thiele method used for finding theoretical stages in a distillation column assumes that the
sensible heat differences are small, because the temperature changes from tray to tray is small.
Trouton’s rule is applicable.
liquid/vapor loading across the column remains constant.
all (a), (b) and (c).
all (a), (b) and (c).
A minimum clearance of about __________ mm is maintained between the distillation column wall and the bubble cap.
19
38
76
95
38
Pick out the wrong statement.
If sufficient residence time (around 8 seconds) is not proivided to the downcoming liquid in the downcomer, it may entrain some vapour.
The liquid head in the downcomer should not be greater than one half the plate spacing to avoid flooding.
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.
none of these.
none of these.
Pick out the wrong statement pertaining to shell and tube heat exchanger.
Clearance between shell & baffles and between tube & baffles should be minimum to avoid by-passing of the fluid, but it should be enough to permit the removal of tube bundle.
Baffles are supported independently of the tubes by tie rods and positioned by spacers.
Tie rods are fixed at one end in the tube sheet by making blind holes and the minimum number of tie rods is 4 with at least 10 mm diameter.
Bracket supports are used for horizontal shell, while saddle support is used for vertical shell.
Bracket supports are used for horizontal shell, while saddle support is used for vertical shell.
Wind load consideration in the design of a support can be neglected, when the vessel is
tall (say 30 metres), but is full of liquid.
tall but empty.
short (< 2 m) and housed indoor.
none of these.
short (< 2 m) and housed indoor.
Souders Brown equation is used for the calculation of the __________ in a continuous distillation column.
diameter of the bubble cap column
diameter of the seive plate column
tray pressure drop
residence time in the downcomer for the disengagement of entrained vapour
diameter of the bubble cap column
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
>1
equal to the order of reaction
> 1
Le/D for a Tee (used as elbow, entering run) would be around
5
60
200
350
60
hint: “tee”»_space;> six”tee”
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”).
half
three fourth
equal to
1.5 times
equal to
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
deformation
shear
elongation
bending
Scale up problem in design based on the similarity concept takes into account __________ similarity.
geometrical
kinematic
dynamic
all (a), (b) and (c)
all (a), (b) and (c)
__________ closure is the weakest enclosure for cylindrical vessels.
Hemispherical
Torispherical
Conical or flat plate
Elliptical
Conical or flat plate
Which of the following efficiencies can be greater than 100% ?
Overall plate efficiency.
Murphree plate efficiency.
Point efficiency.
None of these.
Murphree plate efficiency.
