MPSC Chemical Engineering Optional 2007 Main Exam Paper | Chemical Engineering

Q1.

(a) Describe Ergun equation for flow through packed beds and explain the significance of the terms in the equation.

(b) Describe how the concentration - time data obtained from a batch homogeneous reactor can be analysed and employed to design a plug flow reactor and a continuous stirred tank reactor.

(c) A product stream 1000 kg/hr is cooled from 110°C to 40°C by cooling water
(c) available at 30° C. The temperature rise in the cooling water is 6°C. Which flow pattern will you recommend and why ? (co-current or counter-current)

(d) Explain the statement : "Sulfuric acid plants above 1000 MTPD capacity are deemed as power plants".

(e) A certain liquid of specific gravity 0.8, viscosity 0.6 mPa.s is flowing through a smooth pipe of 5.0 cm inner diameter at a linear velocity of 1.8 m/s. The ratio of the wall shear stress to the average kinetic energy per unit volume of the fluid is known to be inversely proportional to the fourth root of the Reynolds number of the flow and the proportionality constant is 0.078. The pipe has two 90° bends in a total length of 50 m and discharges the liquid at a height of 18 m. If a pump of 50% efficiency is used for the purpose, estimate the power required to operate the pump.

Q2.

(a) each type. Gases comprising of mol % SO₂, 11% O₂ and rest nitrogen are supplied to a

(b) catalytic converter at 430° C. Some of the SO₂ is oxidised to SO₃ in the converter. The outlet temperature of the gases is 600^\circ C. Estimate the composition of gases leaving the converter.

(c) Describe in brief, the various methods of separating solids from a mixture of solids and liquids.
3. Two spherical particles of same size are dropped through a column of a fluid. (a) The particles are made from different materials whose specific gravities are 3.0 and 8.0. The fall of the particles is in the Stoke's law regime. Estimate the ratio of their terminal settling velocities if the specific gravity of the fluid is 1.0. (b) In the operation of a synthetic ammonia plant, a nitrogen-hydrogen mixture (1:3 mol ratio) is fed to the reactor resulting in a 23% conversion to ammonia. Fresh feed Reactor Condenser N₂ - H₂ and Argon Liquid Ammonia Recycled gases Purge stream All of the ammonia formed is separated by condensation and the unconverted gases are recycled to the reactor. The fresh feed of N₂ - H₂ mixture contains 0.17 mol Argon per 100 mol N₂ - H₂ mixture. The concentration of Argon in the gases entering the reactor is to be kept below 6 mol Argon per 100 mol N₂ - H₂ mixture. Estimate the minimum fraction of the recycle that must be purged. Describe in brief, the difference between the behaviour of a compressible and a
(c) non-compressible filter cake.

Q3.

(a) Two spherical particles of same size are dropped through a column of a fluid. The particles are made from different materials whose specific gravities are 3.0 and 8.0. The fall of the particles is in the Stoke's law regime. Estimate the ratio of their terminal settling velocities if the specific gravity of the fluid is 1.0.

(b) In the operation of a synthetic ammonia plant, a nitrogen-hydrogen mixture (1:3 mol ratio) is fed to the reactor resulting in a 23% conversion to ammonia. Fresh feed Reactor Condenser N2 - H2 and Argon Liquid Ammonia Recycled gases Purge stream All of the ammonia formed is separated by condensation and the unconverted gases are recycled to the reactor. The fresh feed of N2 - H2 mixture contains 0.17 mol Argon per 100 mol N2 - H2 mixture. The concentration of Argon in the gases entering the reactor is to be kept below 6 mol Argon per 100 mol N2 - H2 mixture. Estimate the minimum fraction of the recycle that must be purged.

(c) Describe in brief, the difference between the behaviour of a compressible and a non-compressible filter cake.