Plant Design Flashcards
Which of the following seldomly use for pressure vessel construction?
Rimmed steel
Liquid petroleum/fuel storage tanks are built underground when storage capacity is less than ___ kiloliters
45
Le/D of fully opened globe valves
300
Increase in shell passes, the vale of Ft
increases
Holes of a sieve tray are arranged in a triangular pitch of ____ times the hole diameter
2 5 to 5
Stress developed in a material without any permanent set
Elastic limit
In a shell and tube heat exchanger, the tube pitch is defined as
the shortest center to center distance between adjacent tubes
holes of sieve tray are arranged in triangular pitch of ____ times the hole diameter
2.5 to 5
Overall distillation column efficiency for most refinery column can be given by
n = 17 - 61.1 logu
%u = molal average viscosity of feed
In case of bubble cap distillation column of diameter greater than 1.2 m, the cap diameter is about ___ cm
10
tube side pressure drop in a 1-2 heat exchanger is about ___ times that in a 1-1 heat exchanger having same size, number of tubes
8 times
In a heat exchanger, shell side fluid velocity can be changed by changing the tube
layout and pitch
Where does the maximum tensile strength occur in a thick cylindrical vessel subjected to internal pressure?
At the inner surface
It is not desirable to have Ft less than
0.8
A rivetted joint does not fail by ___ of rivets
a. tearing
b. shearing
c. tearing of the plate across
d. none
None of these
Triangular pitch tube layout as compared to square pitch in a shell and tube
permits use of more tubes in a given shell diameter
Bracket supports are the most suitable for supporting ____ vessels
Thick walled vertical vessels
In multipass shell and heat exchanger, the shell side cross flow area does not depend upon
none of these
Steam heat transfer coefficient for design consideration under ordinary conditions
7500 kcal/m² hr °C
True or False. The Fouling factor of river water is less than that of sea water
False
Area increase in raschig ring to form lessing ring
20%
The conical bottom heads used in chemical process equipments has an apex angle of
60°
Smaller sized packings are generally dumped to the packed columns, and the large ones of size greater than ____ mm are individually stacked
75 mm
Shell side heat transfer coefficient of square pitch compared to triangular pitch
less
Factor of safety
Ultimate stress to working stress
Packed towers are normally designed for a pressure drop of about __ mm of water per meter height of packing
20 to 40
Arrangement of distillation column having d=4ft
cross flow
In perforated plate column
a. holes may be 1/18 or 3/16
b. tole hole area if 6-15% of tower cross
c. pressure drop is less compared to bubble cap
d All
All of these
Main purpose of stepping on trays
Facilitate of handling large flows
Pressure drop range in a bag filter
50-150 mm water gauge
Cylindrical vessel shape that can withstand the highest pressure
a. Flat plate
b. Torispherical
c. Ellipsoidal
d. Hemispherical
Ellipsoidal
True ot False. Packed tower is preferred over plate tower if liquids have a foaming tendency
TRUE
True or False. Basket type evaporator is used for high viscosity liquor having large rate of scaling
False
Speed of drum of rotary vacuum filter
0.1 to 2 rpm
Pressure drop to mass velocity in a packed tower at preloading range
∆P = G²
Needle valves are not used in
large diameter pipes
Used to set the diameter of distillation column
Allowable vapor velocity
For reaction orders more than 1, which is the best
a. equal sized reactors
b. small reactor should come first
c. larger reactor should come first
Small reactor should come first
Analytical method for the calculation of theoretical stages in continuous binary distillation
Sorel-Lewis method
Saddle supports are used in supporting
Horizontal cylindrical
Bracket supports are used to support
Thick walled vertical vessels
In distillation columns, the number of bubble caps per tray primarily depends
allowable gas and liquid velocities
Vertical vessels are not supported by
saddles
Column with lowest pressure drop given equal diameters
Packed column
Rivets are specified by
Shank diameter
Diameter of propeller agitator used in agitation tank ranges from ___percent of the tank diameter
15 to 30%
In packed towers provided by saddle packing, liquid distributions are positioned at every ____ times column diameter or 6 m whichever is less
5-8
Optimum reflux ratio is determined by
Total cost consideration
Cooling water fouling factors vary in the range if 0.001 to 0.003
(BTU/hr•ft²•°F)^-1
Maximum liquid gradient over a tray must not exceed
0.5” to 1.25”
Underdesigned steam trap
will cause water hammering in steam line
Speed of industrial paddle agitator
20 to 100 rpm
Strain measured using strain rosetter
Linear strain
No corrosion allowance is required if thickness is
30 mm
In a ______riveted joint, rivets in various rows are opposite of each other
chain
Le/D of a fully open gate valve
7, much less than fully open globe valve
In a distillation column, minimum residence time for liquid at downspout is about
8 seconds
L/D for rotary driers
4 to 10
Bubble cap tray is the most commonly used tray in large distillation column
because of its flexibility and nearly constant efficiency under varying conditions
In shell and tube heat exchanger, straight tie rods are used to
hold baffle in place
Pressure to Inertial forces
Euler
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
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.
Ponchon Savarit
Minimum recommended baffle spacing in a shell and tube heat exchanger is about
0.2D
Thin spherical shells subjected to internal pressure, develop __________ stresses.
Radial
With increase in the reflux ratio for a fixed production from a continuous binary distillation column, the __________ decreases.
Fixed charges increases
The slope of operating line in the rectifying section of a distillation column is unity, if the reflux ratio is
Infinity
With increase in pressure drop (for a given particle size), the dust collection efficiency of a cyclone separator will
Increase
An adequate clearance between the tray and the shell wall of a distillation column is provided to
Allow thermal expansion
True or False. The value of crushing load is more than that of buckling load for long colmns.
False
True or False. The total weight of a dry plate tower is usually much more than that of a dry packed tower designed for the same duty
False
Floating head heat exchangers are used for
cases where temperature difference between the shell and the tubes is more (>50°C).
The most common standard size of bubble caps used in industrial operation
6” cap
4” riser
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
Thickness of the frame of a plate and frame filter as compared to that of plates is
more
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
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
B. 19
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.
b. 600
Ratio of tube length to shell diameter for a shell and tube heat exchanger is
D. Both B and C
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
B. 1
Which of the following types of reactors is the safest from operation point of view ?
A. Vapor phase reactor
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
A. Decreased upward
In the design of paddle agitator, the ratio of paddle diameter to tank diameter is
B. 0.8
Hole diameter of the seive trays in the distillation column ranges from __________ mm
3 to 12.5
Factor of safety (i.e., overdesign factor) in heat transfer equipments is about __________ percent more than the actual/theoretical design factor.
15 to 20
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)
In actual operation of distillation column, the vapour is not distributed uniformly among the bubble caps, primarily because of the
A. Liquid gradient on the tray
The minimum shell thickness for tank ≤ 15 metres diameter is limited to __________ mm, for reasons of elastic stability.
5
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 min of 2” to 5D
Brass valves are usually made for pipe sizes __________ inches.
< or = to 2
In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement
A. higher shell side pressure drop
True or False. Higher pressure fluid stream should be routed through the shell side.
False
True or False. Flat head covers are most suitable for larger vessels operating at very high pressure.
False
Pick out the wrong statement pertaining to the design of a horizontal tube evaporator.
D. Liquor flows inside the tube, while the steam is outside submerging the tube.
___ shapedroof is the most commonly used roof for cylinderical storage tanks.
A. Conical
Pick out the wrong statement pertaining to ‘Horton sphere’ used for the storage of liquid ammonia.
D. Horton sphere is used for the storage of liquid at sub-zero temperature at very high pressure upto 200 kg/cm2.
Value of Peclet number = ∞, is the representative of
Plug Flow
In most of the shell and tube heat exchangers, the tube pitch is generally __________ the tube diameter.
B. 1.25 to 1.50
In a distillation column, bubble caps are located on trays with a pitch of __________ times the outside diameter of the caps
A. 1.3 to 2
For identical operating conditions, the pressure drop over __________ tray is the highest out of the following.
Bubble cap
A perforated plate has holes of diameterdnarranged in a pitchph. Each hole has a tube of I.D.dtpassing through it. The ligament efficiency is given by
C. (Ph - Dt)/Ph
__________ is the determining factor for the number of bubble caps to be used per tray.
A. Permissible slot velocity
True or False. Flash distillation, differential distillation & steam distillation are all continuous distillation processes.
False
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).
C. 650 mmHg
Normal screwed fittings are used for pipes upto a diameter of __________ inches.
B. 3 inches
Diameter of the seive tray column is determined by the
B. Upper limit of vapor velocity
For a given fluid, as the pipe diameter increases, the pumping cost
decreases
Maximum acceptable total liquid gradient over a tray is about __________ mm.
B. 12.5 mm
In case of a ‘thin’ pressure vessel, the ratio of its diameter to wall thickness is
B. > 10
High pressure fluid in a shell and tube heat exchanger should preferably be routed through the
A. tubes to avoid expansion of high pressure shell construction
Emf developed by a thermocouple, while measuring a temperature of 600°C is about 5.5 mV. The type of thermocouple used is
Platinum-Platinum/Rhodium
Which of the following relates the absorption & evolution of heat at the junctions of a thermocouple to the current flow in the circuit?
Seedbeck Effect
