Process Equipment and Plant Design (Set 3) Flashcards
Concepts and heuristics necessary for design of equipment, processes, and process systems.
____ tower is the most suitable gas-liquid contacting device involving highly corrosive fluids.
Packed
At equal mass velocities, the values of film co-efficients for gases as compared to that for liquids are generally.
lower
The ratio of the largest load in a test to the original cross-sectional area of the test specimen is called the ____ stress.
ultimate
Baffle spacing is generally ____ the I.D. of the shell.
a. more than
b. not greater than
c. not less than one fifth of
d. both (b) and (c)
both (b) and (c)
The wall thickness of thin cylindrical shell with hemispherical ends is ____ that of the spherical ends.
more than
A ‘rupture disc’ is provided in chemical equipments as an accessory meant for
relieving excess pressure.
In a vertical short tube evaporator (Calendria type), the
a. 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.
b. area of central downtake is equal to 40 to 100% of total cross-sectional area of the surrounding tube.
c. liquor is inside the tube while the steam is outside the tube.
d. all (a), (b) & (c).
all (a), (b) & (c).
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
a. U-bend
b. floating head tube sheet
either (a) or (b)
In a shell and tube heat exchanger, the shortest centre to centre distance between the adjacent tubes is
called tube pitch.
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.
Minimum tube pitch recommended for shell and tube heat exchangers is about ____ times the outside diameter of the tube.
1.25
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
Slope of countercurrent flow rotary drier is in the range of ____ meter/metre.
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/15th
Seamless pipe is made
a. from rolled strips formed into cylinders and seam-welded.
b. by extrusion & casting into static and centrifugal molds.
c. by forging a solid round, piercing it by simultaneously rotating & forcing it over a piercer point and further reducing it by rolling gas drawing.
both (b) and (c).
The thermal stress in a metallic bar does not depend upon the
cross-sectional area.
The minimum baffle height should be
twice the impeller diameter.
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
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
The normal range of velocity of water in pipes is ____ m/sec.
1-2
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
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.
In a ____ rivetted joint, the number of rivets decreases from the innermost row to the outermost row.
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.
10 to 20
Heat transfer co-efficient for a horizontal condenser as compared to a vertical condenser operating under similar conditions is
about 3 times
Pick out the wrong statement pertaining to the design of the distillation column.
a. Generally, a skirt clerance of 0.5” to 1.5’ is recommended to prevent plugging of the slots by residue build up.
b. The purpose of the slot is to disperse the gas into the liquid in the form of small bubbles.
c. If sufficient slot area is not provided, the gas may pass through the skirt clearance.
none of these.
The longitudinal stress induced in a thin walled cylinderical vessel under internal pressure is
pd/4t
In distillation columns, bubble caps are held in place over trays by
both (b) and (c)
“a hold down bar” and “bolts”
The buckling tendency of compression members is always in the direction of the
least radius of gyration.
In case of plain carbon steel, butt welded joints are used for shell plate thickness ≤ ____ cms.
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.
4
Hoop (circumferential) stress induced in a thin walled ‘Horton Sphere’ used for the storage of liquid ammonia under pressure is
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.
The raio, propeller agitator dia/tank dia is normally taken as
0.15-030
A/an ____ is used for changing the direction of a pipeline.
elbow
Maximum plate efficiency is achieved in case of ____ flow.
cross
The LMTD correction factor (FT) is defined as the
ratio of true temperature difference to the 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.
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
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