Chemical Engineering Archives

3971. The diameter of a propeller agitator used in agitation tank ranges from __________ percent of the tank diameter and its peripherial speed is normally 300 to 500 metres/minute.

5 to 10

15 to 30

40 to 50

55 to 75

✅ The correct answer is option B.

3972. In a rotary drier, the average retention time of solid is(where Z = length of the drier, metres ρ = apparent solid density, kg/m3 L = flow rate of dry solids, kg/see. m2 drier cross-section H = hold up of solid.)

✅ The correct answer is option A.

3973. __________ shaped roof is most commonly used for cylindrical tanks.

Cone

Dome

Umbrella

Flat

✅ The correct answer is option A.

3974. When one of the fluids is highly corrosive and has fouling tendency, it should

preferably flow inside the tube for its easier internal cleaning.

perferably flow outside the tube.

flow at a very slow velocity.

flow outside the tube, when the flow is counter-current and inside the tube when the flow is co-current.

✅ The correct answer is option A.

3975. 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

only if the opening is on spherical vessel.

only if the opening is on a vertical cylinderical vessel.

only if the opening is on a horizontal cylinderical vessel.

irrespective of the shape of the vessel.

✅ The correct answer is option D.

3976. Weep holes provided in the plates of a distillation column

facilitate draining out liquid from a tray when the unit is not in operation.

are normally located near the overflow weir so that any delivery of liquid during operation follows approximately the same path as the overflow fluid.

must be large enough (usually 1/4″ to 5/8″ dia) to prevent plugging but should not deliver excessive amount of fluid during operation.

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

✅ The correct answer is option D.

3977. In vapour compression refrigeration system, if the evaporator temperature and the condenser temperatures are -13°C and 37°C respetively, the Carnot COP will be

A. 5.2

B. 6.2

C. 0.168

D. Data insufficient, can’t be found out

✅ The correct answer is option A.

3978. The necessary condition for phase equilibrium in a multiphase system of N components is that the

A. Chemical potentials of a given component should be equal in all phases

B. Chemical potentials of all components should be same in a particular phase

C. Sum of the chemical potentials of any given component in all the phases should be the same

D. None of these

✅ The correct answer is option A.

3979. Gases are cooled in Joule-Thomson expansion, when it is __________ inversion temperature.

A. Below

B. At

C. Above

D. Either B or C

✅ The correct answer is option A.

3980. No work is done by the system, when a reaction occurs at constant

A. Volume

B. Temperature

C. Pressure

D. None of these

✅ The correct answer is option A.