S3

Question 1

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.

Answer 1

19

Question 2

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.

Answer 2

600

Question 3

The dust collection efficiency of a cyclone separator

Answer 3

none of these.

Question 4

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

Answer 4

1

Question 5

Which of the following types of reactors is the safest from operation point of view?

Answer 5

A vapor phase reactor.

Question 5

In a bag filter, the pressure drop increases directly as the

Answer 5

density of the gas and inversely as viscosity of the gas.

Question 6

The LMTD correction factor (FT) is applied in ________ heat exchangers.

Answer 6

all multipass

Question 7

Movement of pipeline caused by thermal expansion is taken care by providing

Answer 7

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

Question 8

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

Answer 8

decreases upwards.

Question 9

In the design of a paddle agitator, the ratio Paddle Dia / Tank Dia is normally taken as

Answer 9

0.8

Question 10

The design stress, which is more than the damaging stress, is the least unit stress that will render a member unfit for service before the end of its normal life. The design stress factor or factor of safety indicates the margin between design stress and the ________ stress.

Answer 10

damaging

Question 11

Hole diameter of the seive trays in the distillation column ranges from ________ mm.

Answer 11

3 to 12.5

Question 12

Factor of safety (i.e., overdesign factor) in heat transfer equipments is about ________ percent more than the actual/theoretical design factor.

Answer 12

15-20

Question 13

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

Answer 13

d1 / d1 + d2

Question 14

In actual operation of distillation column, the vapour is not distributed uniformly among the bubble caps, primarily because of the

Answer 14

liquid gradient on the tray.

Question 15

The minimum shell thickness for tank ≤ 15 metres diameter is limited to __________ mm, for reasons of elastic stability.

Answer 15

5

Question 16

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

Answer 16

D/5 or minimum 2” to 5D.

Question 17

Brass valves are usually made for pipe sizes __________ inches.

Answer 17

≤1

Question 18

At the following point for a given packing and set of fluids, the pressure drop per metre of packed height, with variation in fluid rates and operating pressure

Answer 18

remains same

Question 19

In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement

Answer 19

results in higher shell side pressure drop.

Question 20

Pick out the wrong statement about routing of fluids in a shell and tube heat exchanger.

Answer 20

Higher pressure fluid stream should be routed through the shell side.

Question 21

The necessary wall thickness for a metallic storage vessel is a function of the

Answer 21

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

Question 22

In a multiple effect evaporator system having ‘n’ effects, the amount of water evaporated per unit surface area in approximately equal to __________ times that in a single effect.

Answer 22

(1/n)th

Question 23

Pick out the wrong statement

Answer 23

Flat head covers are most suitable for larger vessels operating at very high pressure.

Question 24

Pick out the wrong statement pertaining to the design of a horizontal tube evaporator.

Answer 24

Liquor flows inside the tube, while the steam is outside submerging the tube.

Question 24

Weep holes provided in the plates of a distillation column

Answer 24

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

Question 25

Steam is preferred to be used as a heating medium in heat exchangers, because of its

Answer 25

high latent heat.

Question 26

_________ shapedroof is the most commonly used roof for cylinderical storage tanks.

Answer 26

Conical

Question 27

Pick out the wrong statement pertaining to ‘Horton sphere’ used for the storage of liquid ammonia.

Answer 27

Horton sphere is used for the storage of liquid at sub-zero temperature at very high pressure upto 200 kg/cm2 .

Question 28

Value of Peclet number = ∞, is the representative of

Answer 28

plug flow.

Question 29

Le/D for a Tee (used as elbow, entering branch) would be

Answer 29

both (b) and (c).

Question 30

In most of the shell and tube heat exchangers, the tube pitch is generally __________ the tube diameter.

Answer 30

1.25-1.50 times

Question 31

In a distillation column, bubble caps are located on trays with a pitch of __________ times the outside diameter of the caps.

Answer 31

1.3 to 2

Question 32

1.2 to 3.8 cms is the value of the

Answer 32

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

Question 33

Accidents in chemical plants are mostly due to

Answer 33

faulty operating procedures.

Question 34

For identical operating conditions, the pressure drop over __________ tray is the highest out of the following.

Answer 34

bubble cap

Question 35

A perforated plate has holes of diameter dn arranged in a pitch ph. Each hole has a tube of I.D. dt passing through it. The ligament efficiency is given by

Answer 35

(ph - dt) / ph

Question 36

__________ is the determining factor for the number of bubble caps to be used per tray.

Answer 36

Permissible slot velocity

Question 37

Pick out the wrong statement about distillation operation

Answer 37

Flash distillation, differential distillation & steam distillation are all continuous distillation processes.

Question 38

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).

Answer 38

650

Question 39

Which of the following is the best tube material from thermal conductivity point of view alone?

Answer 39

Copper

Question 40

Normal screwed fittings are used for pipes upto a diameter of __________ inches.

Answer 40

3

Question 41

In a shell and tube heat exchanger, the clearance of the tube is generally

Answer 41

not less than one-fourth of the tube diameter or 3/16”.

Question 42

Diameter of the seive tray column is determined by the

Answer 42

upper limit of the vapour velocity.

Question 43

For a given fluid, as the pipe diameter increases, the pumping cost

Answer 43

decreases.

Question 44

Maximum acceptable total liquid gradient over a tray is about __________ mm.

Answer 44

12.5

Question 45

In case of a ‘thin’ pressure vessel, the ratio of its diameter to wall thickness is

Answer 45

> 10

Question 46

High pressure fluid in a shell and tube heat exchanger should preferably be routed through the

Answer 46

tubes to avoid the expansion of high pressure shell construction.

Question 47

Bubble cap tray is the most commonly used tray in large distillation column, because

Answer 47

of its flexibility and nearly constant efficiency under varying conditions of operation.