Q3.
(a)
Explain the factors to be considered for selection of a solvent in absorption.
(b)
Derive an equation for estimation of time of drying when met solid contains both bound and unbound moisture.
(c)
Ammonia is stripped from a dilute aqueous solution by counter-current contact with air in a column containing seven sieve trays. The equilibrium relationship is ye = 0.8 xe and molar flow rate of air is 1.5 times that of the solution. 90% of NH3 is to be removed. How many ideal stages does the column have and what is the stage efficiency?
Q4.
(a)
Give detailed procedure for calculation of Heat load of a furnace.
(b)
Derive an equation for estimation of overall heat transfer coefficient from individual coefficients.
(c)
A solution of organic colloids is to be concentrated from 15 to 50 per cent solids in a vertical-tube evaporator. The solution has a negligible elevation in boiling point, and the specific heat of the feed is 0.93. Saturated steam is available at 0.8 atm abs, and the pressure in the condenser is 100 mm Hg abs. The feed enters at 15°C. The overall coefficient is 1,700 W/m^2.oC. The evaporator must evaporate 25,000 kg of water per hour. How many square metres of surface are required, and what is the steam consumption in kilograms per hour? Enthalpy of super heated water vapour is 575 kcal/kg and that of steam is 4406 kcal/kg. Temperature in evaporator is 50°C. Enthalpy of thick liquor is 122 kcal/kg, enthalpy of feed is 30 kcal/kg.
Section B
Q5.
Answer all parts in this question :
(a)
List out and explain the various static and dynamic characteristics of a Temperature measuring Instrument.
(b)
Define Stability criteria and explain Routh test method for finding the stability of the control system.
(c)
What are the advantages of liquid membrane process over liquid extract.
(d)
Explain the Pervaporation operation.
(e)
What is meant by crossover frequency of a control system?
(f)
Give the transfer function for transportation lag.
(g)
Distinguish between Reverse Osmosis and Ultra Filtration.
Q6.
(a)
What is the principle of Electro-Dialysis? List out applications of this operation.
(b)
What are the commercial applications of dialysis operation?
(c)
A gas containing 70 per cent H2, 24 per cent CH4, and 6 per cent C2H6 is to be separated into a nearly pure H2 stream and a fuel gas using a hollow-fibre permeate with a selectivity of 100 for H2/CH_4. (a) If the upstream and downstream pressures are 40 and 20 atmospheres absolute, what fraction of H2 in the feed is recovered in permeate if the permeate is 96% H2? What is the stage cut? (b) How much more H2 could be recovered by lowering the permeate pressure to 12 atmospheres absolute?
Q7.
(a)
Give the material of construction for Storage Vessels to handle Hydrochloric Acid of various compositions.
(b)
Discuss the design procedure of closures flat and elliptical head.
(c)
Estimate the thickness of the shell of a spherical process vessel of diameter 2 mts. The vessel is to be operated at a pressure of 1.5 MN/m^2 (absolute). Take the design pressure as 10% above the operating pressure. Allowable stress for the material of the vessel is 85 MN/m^2. Weld is fully radiographed. A corrosion allowance of 2 mm may be taken. Joint efficiency can be taken as 95%.
Q8.
(a)
Explain the PID control action of a Pneumatic controller with a neat sketch.
(b)
For the transfer function shown below, sketch carefully the gain versus frequency portion of the asymptotic plot of the Bode diagram. Determine the actual (exact) value of gain and phase angle at omega = 1. Determine the phase angle as omega ightarrow infty G(s) = rac{2(0.1s + 1)}{S2(10s + 1)}
Indicate very clearly the slopes of the asymptotic Bode diagram of G(s).
