Process Equipment and Plant Design

Question 1

Fresh water carrying pipelines in chemical industries are coloured with __________ color.

Answer 1

sea green

Question 2

Which of the following material is seldom used for pressure vessel construction ?

Answer 2

Rimmed steel

Question 3

The ratio of shear stress to shear strain is called

Answer 3

shear modulus

Question 4

25 per cent cut segmental baffle means that the baffle

Answer 4

height is 75% of the I.D. of the shell.

Question 5

Liquid/petroleum fuel storage tanks are built underground (as in case of petrol pumps), when the storage capacity is less than __________ kilolitres.

Answer 5

45

Question 6

Le/D for fully open globe value may be around

Answer 6

300

Question 7

Lug support is

the most suitable for thick vertical vessel.

same as bracket support.

provided usually for vessels of much smaller height than skirt supported vessels.

all (a), (b) and (c).

Answer 7

all (a), (b) and (c).

Question 8

Pick out the wrong statement pertaining to the use of valve tray, seive tray and bubble cap trays in continuous distillation column.

Answer 8

Maintenance cost for valve and seive trays are comparatively more than bubble cap tray due to their relatively complicated construction features.

Question 9

With increase in the number of shell passes, the value of Ft

Answer 9

increases

Question 10

Holes of a sieve tray are arranged in triangular pitch of __________ times the hole diameter.

Answer 10

2.5 to 5

Question 11

The stress developed in a material without any permanent set is called the

Answer 11

elastic limit

Question 12

In a shell and tube heat exchanger, the ‘tube pitch’ is defined as the

Answer 12

shortest centre to centre distance between adjacent tubes.

Question 13

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 ?

Sensible heat changes for vapour & liquid are negligibly small.

Reflux is not a saturated liquid.

Molar latent heat of the two components are equal.

Heat of mixing of normal liquid is assumed to be zero.

Answer 13

Reflux is not a saturated liquid

Question 14

.
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)

Answer 14

η = 17 - 61.1 log μ

Question 15

The value of fouling factor depends upon the
characteristic of process fluid.

velocity of process fluid containing suspended solids.

suspended solids in the fluid.
all (a), (b) and (c).

Answer 15

all (a), (b) and (c).

Question 16

In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about __________ cms.

Answer 16

10

Question 17

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.

Answer 17

8

Question 18

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

Answer 18

(1.2)^5/3

Question 19

.
In a heat exchanger, shell side fluid velocity can be changed by changing the tube

layout
pitch
both (a) & (b)

Answer 19

both (a) & (b)

Question 20

Where does the maximum tensile strength occur in a thick cylindrical vessel subjected to internal pressure ?

Answer 20

At the inner surface.

Question 21

It is not desirable to design a heat exchanger for LMTD correction factor, FT, of less than

Answer 21

0.80

Question 22

A rivetted joint does not fail by __________ of rivets.

tearing
shearing
tearing of the plate across a row
none of these

Answer 22

none of these

Question 23

Triangular pitch tube layout as compared to square pitch in a shell and tube heat exchanger

Answer 23

permits the use of more tubes in a given shell diameter.

Question 24

Bracket supports are the most suitable for supporting __________ vessels.

Answer 24

thick walled vertical

Question 25

In a multipass shell and tube heat exchanger, the shell side cross flow area depends upon

baffle spacing
clearance
pitch
all of these

Answer 25

all of these

Question 26

Two iron pipes of the same nominal diameter but different schedule numbers will have the same

Answer 26

inside diameter

Question 27

Steam side heat transfer co-efficient for design consideration under ordinary condition can be assumed to be about __________ kcal/hr.m2.°C.

Answer 27

7500

Question 28

Pick out the wrong statement

For all the cylindrical process vessels operating above atmospheric pressure, formed heads are used for closing the vessel.

Fouling factor of river water is less than that of sea water.

Risers provided in bubble cap trays in the distillation column facilitate the flow of both liquid and vapor.

both (b) and (c)

Answer 28

both (b) and (c)

Question 29

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.

Answer 29

20

Question 30

In chemical process equipments, the conical bottom heads used, usually has an apex angle of

Answer 30

60

Question 31

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.

Answer 31

75

Question 32

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

Answer 32

less

Question 33

Correct use of ‘factor of safety’ is very important in equipment design. It is defined as the ratio of the

Answer 33

ultimate stress to working stress.

Question 34

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.

Answer 34

20-40

Question 35

__________ tray arrangement is recommended for distillation column having diameter upto 4 ft.

Answer 35

Cross flow

Question 36

What is the value of ‘q’ for saturated liquid feed to a distillation column ?

Answer 36

1

Question 37

In perforated plate towers, the

hole sizes may be around 1/8” or 3/16”.

total hole area may be around 6 to 15% of tower cross-sectional area.

pressure drop is less compared is similar bubble cap towers.

all (a), (b) and (c).

Answer 37

all (a), (b) and (c).

Question 38

The main purpose of providing stepping on the trays is to

Answer 38

facilitate handling of large flow rate of liquid.

Question 39

The operating pressure drop range in a bag filter is about __________ mm water gauge.

Answer 39

50-150

Question 40

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.

Answer 40

Ellipsoidal

Question 41

For laminar flow (NRe < 2100) in steel pipe, the optimum inside pipe diameter is given by

Answer 41

Di, opt = 3 Q^0.36 ρ^0.18

Question 42

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.

Answer 42

Packed towers are generally preferred over plate towers, if the liquids have a foaming tendency.

Question 43

Wall thickness of schedule 40 pipe as compared to that of schedule 80 pipe is

Answer 43

less

Question 44

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.

Answer 44

It is used for high viscosity liquor having large rate of scaling.

Question 45

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.

The pressure drop due to the caps & slots and the static submergence should be as high as practicable for reasonable operation.

Tendency towards stable operation is increased by increasing the skirt clearance of the caps, lowering the rate of liquid flow per unit plate width or increasing the spacing between the caps.

The dimensionless ratio of liquid gradient to pressure drop head caused by the bubble cap assembly should be less than 0.4.

none of these.

Answer 45

none of these.

Question 46

Speed of the drum of the rotary vacuum filter normally ranges from __________ rpm.

Answer 46

0.1 to 2

Question 47

A stuffing box is used for

Answer 47

prevention of fluid leakage around moving parts.

Question 48

Pressure drop (Δp) and the superficial gas mass velocity (G) in case of packed absorption tower operating in the preloading range are related as

Answer 48

Δp = G^2

Question 49

Pick out the wrong statement.
In an agitated vertical cylinderical reaction vessel, the

ratio of liquid depth to tank diameter (i.e. the filling ratio) recommended for most purposes is 1.

filling ratio for dispersing gas in a liquid is 2 for sufficiently long contact period.

flat bottom and conical bottom vessels have low agitation efficiency for agitation of heavy solids in liquids.

dished bottom vessel has very high power consumption.

Answer 49

dished bottom vessel has very high power consumption.