What is Elutriation ?

Elutriation: It is a separation method, which depends on the settling velocity of the particles in the fluid.

In this process of separation, the material is placed in a rising fluid having a fixed upward velocity, particles whose normal falling velocity is less than the velocity of the fluid will be carried upward and out of the vessel. If fractions obtained from a series of fluid velocities are collected and weighed, a complete size analysis may be obtained.

What is jigging and where it is used ?

 Jigging:

Jigging is a separation method in which the particle are separated by using the density difference between them. 

Jigging is a method of gravitational preparation of natural resources, based on separation of mineral mixture on density in vertically oscillating water stream.

Usually it is used to separate metal slag form metals.

When reflux ratio to the column is minimum and zero, what are the requirements in column

When reflux ratio is minimum, column requires maximum number of trays and minimum reboiler load for a required separation. To avoid this problem of infinite trays we use optimum reflux ratio.

When reflux ratio is zero, column requires infinite number of trays and minimum reboiler load for a required separation. To avoid this problem of infinite trays we use optimum reflux ratio.

Define Intensive and extensive properties, give examples for them

Intensive and Extensive properties:

Extensive property: Is defined as one which depends on quantity of matter specified in the system.

Examples: Total mass, volume, Energy, enthalpy,

Intensive property:

It is defined as one which doesn't depends on the quantity of matter present in the system.


Examples: Temperature, pressure,Molar enthalpy, molar volume

IFS Chemical Engineering question paper, 2005, Indian Forest Service, test papers

SECTION A

1. Answer any four of the following: 
(a) Find the first-order rate constant for the disappearance of A in the gaseous reaction 2A → R, holding the pressure constant, the volume of the reaction mixture starting with 80 per cent A decreases by 20 per cent in 3 mm. (10)

(b) A solution contains 50 per cent benzene, 30 per cent toluene and 20% xylene by weight at 100° C. The vapours are in contact with the solutions. Calculate total pressure and mole per cent composition of liquid and vapour: (10)

(c) Show that the internal energy of an ideal gas is a function of temperature only. (10)

(d) For adiabatic batch reactor, derive an expression to determine the time required to achieve a desired conversion. (10)

(e) Define Bubble point and Dew point. Explain in detail how to calculate bubble point or dew point of given binary mixture. (10)

2. The elementary reaction. A + B → R + S is effected in a set up consisting of a mixed reactor into which two reactant solutions are introduced followed by a PFR. A large enough of excess of B is used so that the reaction is first order w.r.t. A. It is proposed to reverse the order of two units. How does this change affect the conversion? (40)
 
3. A high purity limestone is burnt in a lime kiln which is fired externally with a coal containing 75.5 per cent C, 5.5 per cent H, 1.6 per cent N, 1.1 per cent S, 7.6 per cent and rest ash. The stack gas analysis is 20.2% CO2, 7.1% O2 and rest N2, Calculate-
(a) kg limestone burnt/kg of coal;
(b) excess air used for combustion. (40)

4. One mole of an ideal gas initially at P1 and T1 is compressed reversibly and adiabatically till the pressure is P2 and then it is cooled at constant volume to the initial pressure, finally the gas is restored to the initial state through an isobaric process. Calculate the work done by the process. (40)

SECTION – B

5. Answer any four of the following:(a) Define depreciation. What are the different methods for determining depriciation? Explain the method, sum of the years digit method. (10)

(b) Explain briefly the factors to be considered for the location of a chemical plant. (10)
(c) Describe the manufacture of caustic soda by either diaphragm or mercury cell process. Discuss the pollution aspects of this industry. (10)

(d) Explain briefly the pollutants emitted from a tanning industry. (10)

(e) Explain the cracking and polymerisation of petroleum fractions. (10)

6. (a) Explain the break-even analysis and its equation. (10)

(b) A Project can produce 12000 units per year at 100 per cent capacity. The variable cost per unit is Rs. 3 at 100 per cent capacity. Fixed costs are Rs. 10,000 per year. Find the break-even point if the selling price is Rs. 5/ unit. Now the manufacturer finds that he can sell only 80% at Rs 5/ unit. How much should he charge for additional units if he brings production upto 100 per cent capacity and increases profits after taxes by an additional amount of Rs. 1,000? Use tax rate for the above problem 52 per cent. . (30)

7. (a) Describe the process with neat flow sheet of the manufacture of ethyl alcohol. (30)(b) Discuss the applications of following products: (10)

(i) Enamel paint (ii) Rancidity.

8. (a) Discuss the methods possible for preventing various industrial hazards. (20)(b) Explain primary treatment method of waste-water treatment. (20)