Engineering Questions with Answers - Multiple Choice Questions

# Distillation Design MCQ’s – Theoretical Stages

1 - Question

An ideal distillation stage is the one that
b) Operates at High temperature
c) Operates at Low pressure
d) Operates at high pressure

Explanation: An ideal distillation stage operates at steady state has liquid product and vapor product, i.e. Liquid rate equals the gas flow rate.

2 - Question

When heat is supplied to bottom of liquid stage to vaporize a portion it is called
a) Condensing
b) Boil up
c) Cooling
d) Desalting

Explanation: Such operations used in stripping section called as Boil up, the boiler is used as a heat exchanger to reheat the condensed liquid.

3 - Question

When Cooling is applied to condense a part of overhead product it is called
a) Reflux
b) Dew point
c) Boil Up
d) Relative BP

Explanation: Such operations is called as Rectifying stages and called Reflux, It is also called the ratio of distillate and liquid flow rate.

4 - Question

When rectifying and stripping both are combined in single stage process this is
a) Differentiation
b) Fractionation
c) Recycle
d) Purging

Explanation: Such is an operation is also called Fractional Distillation, The moles of the components reduce with respect to time in this operation.

5 - Question

Minimum number of trays can be calculated using
a) Bernoulli’s Eon
b) Henry’s Law
c) Fenske’s Equation
d) Homotomy Equation

Explanation: Minimum number of trays can be easily calculated using Fenske’s equation with use of relative volatility.

6 - Question

The external reflux ratio can be defined as
a) L0/D
b) D/L
c) D0/L
d) V/L

Explanation: The reflux ratio is defined as the ratio of liquid flow rate and distilled flow rate, also this is called as the slope of rectifying line.

7 - Question

The boil up ratio can be defined as ratio of
a) V/L
b) D/V
c) V/W
d) L/W

Explanation: Boil up ratio is the ratio of vapor leaving the rebuilder to liquid at bottom product, also it is defined as the slope of stripping line.

8 - Question

Optimum reflux ratio ranges between
a) 2 to 5
b) 2 to 3
c) 1.0 to 1 .5
d) 1.0 to 2.5

Explanation: Best optimum reflux is between ranges. 1.0<R<1.5, as it is very close to unity the optimum conditions are best condition to operate.

9 - Question

If stages are fixed, then Reflux ratio
a) Decreases
b) Increases
c) Equates to 0
d) Approaches infinity.

Explanation: The stages and the reflux ratio are directly proportional, while when it approaches to 0 the distillate is not withdrawn and if infinite all feed is withdrawn.

10 - Question

If reflux increases, then the cost of operation
a) First increases then decreases
b) Goes on increasing
c) Approaches infinity
d) First decreases then increases