Process Equipment and Plant Design (Set 1) Flashcards
Concepts and heuristics necessary for design of equipment, processes, and process systems.
Fresh water carrying pipelines in chemical industries are coloured with ____ color.
sea green
Which of the following material is seldom used for pressure vessel construction?
Rimmed steel
The ratio of shear stress to shear strain is called
shear modulus
25 per cent cut segmental baffle means that the baffle
height is 75% of the I.D. of the shell.
Liquid/petroleum fuel storage tanks are built underground (as in case of petrol pumps), when the storage capacity is less than ____ kilolitres.
45
Le/D for fully open globe value may be around
300
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.
all (a), (b) and (c).
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.
With increase in the number of shell passes, the value of FT
increases
Holes of a sieve tray are arranged in triangular pitch of ____ times the hole diameter.
2.5 to 5
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
The stress developed in a material without any permanent set is called the
elastic limit
In a shell and tube heat exchanger, the ‘tube pitch’ is defined as the
shortest centre to centre distance between adjacent tubes.
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.
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
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.
all (a), (b) and (c).
In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about ____ cms.
10
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
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
In a heat exchanger, shell side fluid velocity can be changed by changing the tube
a. layout
b. pitch
both (a) & (b)
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 design a heat exchanger for LMTD correction factor, FT, of less than
0.8
A rivetted joint does not fail by ____ of rivets.
a. tearing
b. shearing
c. tearing of the plate across a row
none of these
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.
Bracket supports are the most suitable for supporting ____ vessels.
thick walled vertical
In a multipass shell and tube heat exchanger, the shell side cross flow area does not depend upon
a. baffle spacing
b. clearance
c. pitch
none of these
Two iron pipes of the same nominal diameter but different schedule numbers will have the same
inside diameter
Steam side heat transfer co-efficient for design consideration under ordinary condition can be assumed to be about ____ kcal/hr.m2.°C.
7500
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.
both (b) and (c).
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
In chemical process equipments, the conical bottom heads used, usually 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 stacked individually, which provides better control over bed porosity and offers lower gas pressure drop.
75
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
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.
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
____ tray arrangement is recommended for distillation column having diameter upto 4 ft.
Cross flow
What is the value of ‘q’ for saturated liquid feed to a distillation column?
1
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.
all (a), (b) and (c).
The main purpose of providing stepping on the trays is to
facilitate handling of large flow rate of liquid.
The operating pressure drop range in a bag filter is about ____ mm water gauge.
50-150
