Chemical Engineering Archives

4021. Which of the following is not a graphical method (but is an analytical method) for the calculation of theoretical number of stages in case of continuous binary distillation?

Sorel-Lewis method.

McCabe-Thiele’s method.

Ponchon-Savarit method.

none of these.

✅ The correct answer is option A.

4022. The stress developed in a material without any permanent set is called the

ultimate stress

yield stress

elastic limit

breaking stress

✅ The correct answer is option C.

4023. 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.

1 to 5

10 to 20

30 to 40

40 to 50

✅ The correct answer is option B.

4024. __________ dished head is the strongest of all.

Hemispherical

Elliptical

Torispherical

none of these

✅ The correct answer is option A.

4025. 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.

✅ The correct answer is option B.

4026. Normal screwed fittings are used for pipes upto a diameter of __________ inches.

1.5

✅ The correct answer is option B.

4027. For laminar flow (NRe < 2100) in steel pipe, the optimum inside pipe diameter is given by

Di, opt = 3 Q0.36 ρ0.18

Di, opt = 3.9 Q0.45 . ρ0.23

Di, opt = 7.6 Q0.36 . ρ0.9

Di, opt = 3 Q0.36 . ρ1.86 μ0.08

✅ The correct answer is option A.

4028. In the case of a shell and tube heat exchanger, the logarithmic mean temperature difference

is always less than arithmetic average value.

is always more than arithmetic mean value and the geometric mean value.

is always less than arithmetic mean value, but more than geometric mean value.

may be either more or less than geometric mean and arithmetic mean value depending upon whether the flow of stream is co-current or counter-current.

✅ The correct answer is option A.

4029. Joint efficiency (J) for a seamless pipe is

0.85

1.2

< 0.5

✅ The correct answer is option A.

4030. Number of evaporators which can be used in service in a multiple effect evaporation system is limited by the

practical limit reached, due to low heat transfer rate because of inadequate temperature difference.

economic limit reached, when the plant cost exceeds the saving of steam.

both (a) & (b).

neither (a) nor (b).

✅ The correct answer is option C.