Describe effect of increase in reflux ratio on number of theoretical stages and utility requirement with graph.
[3 marks]Discuss selection criteria between kettle type and thermosyphon reboiler.
[4 marks]Explain use of baffles, tie rods, spacers, tube side pass partition plate, shell side pass partition plate, tube sheet and expansion joints in shell and tube heat exchanger.
[7 marks]Explain merits and demerits of hot oil over saturated steam as a heating medium.
[3 marks]Discuss Tinker’s flow model with neat figure.
[4 marks]Discuss step wise design procedure for shell and tube heat exchanger without phase change.
[7 marks]In vertical thermosyphon reboiler recirculation ratio is fixed by trial and error method. Discuss in detail that, how to find or fix the recirculation ratio in the following conditions: 1. ΔPav > ΔPt 2. ΔPav << ΔPt 3. ΔPav ≈ ΔPt
[7 marks]Discuss steps to prevent flooding and weeping in distillation column.
[3 marks]Discuss importance of gas distributor, liquid distributor, liquid redistributor and structured and random packing in packed column operation.
[4 marks]Discuss merits and demerits of vacuum distillation over atmospheric distillation with appropriate example.
[7 marks]Calculate overall heat transfer coefficient for kettle type reboiler, which vaporizes 7160 kg/hr of n-butane at 5.84 bar. Also check that actual heat flux is less than the critical heat flux or not. n-butane is available at saturated liquid condition at given pressure. Saturated steam available at 1.7 bar pressure and 115.2 °Ctemperature is to be used as a heating medium. Use following data for calculation purpose. Properties of n-butane are given at 5.84 bar pressure. Latent heat of vaporization of n-butane 326 kJ/kg Boiling point of n-butane 56.1 °C Critical pressure of n-butane 38 bar Steam side heat transfer coefficient 8000 W/m2°C Steam side fouling coefficient 5000 W/m2°C n-butane side fouling coefficient 10000 W/m2°C Surface tension 9.7 X 10-3 N/m Density of liquid n-butane 550 kg/m3 Density of vapor n-butane 12.6 kg/m3 Type of tube U-tube Nominal length of tube 4.8 m Outside diameter of tube 30 mm1 Inside diameter of tube 25 mm Tube pitch Square Tube pitch to Outside diameter tube ratio 1.5 Thermal conductivity of tube material 55 W/m°C Constant Kfor square pitch 0.44 b
[14 marks]List factors affecting selection of trays in tray column. Discuss any one of them in detail.
[3 marks]Discuss selection criterion between horizontal and vertical condenser.
[4 marks]Discuss stepwise procedure for determination of minimum reflux ratio in binary distillation system.
[7 marks]List important industrial application of liquid-liquid extraction.
[3 marks]Differentiate between jet flooding and downcomer flooding.
[4 marks]Discuss stepwise design procedure for horizontal and vertical gravity decanter.
[7 marks]Estimate minimum reflux ratio and minimum number of ideal stages needed for the butane-pentane splitter defined by the compositions given in table below. Also investigate effect of reflux ratio on ideal stages. The column is operated at a pressure of 8.3 bar. The feed is at its boiling point. Top and bottom temperatures are 65 ˚Cand 120 ˚Crespectively. Component Feed, kmol/hr Distillate, kmol/hr Bottom, kmol/hr Propane 5 5 ? i-Butane 15 15 ? n-Butane 25 24 ? i-Pentane 20 ? 19 n-Pentane 35 ? 35 Relative volatilities at top and bottom are listed in table below. Component Top Bottom Propane 5.5 4.5 i-Butane 2.7 2.5 n-Butane 2.1 i-Pentane 1 1 n-Pentane 0.84 0.85
[2 marks]State the merits and demerits of falling film absorber.
[3 marks]Explain function of downcomer and discuss the different types of downcomer used in distillation column.
[4 marks]Explain concept of NPSH in pumping system. Distinguish between (NPSH) and A (NPSH) . If (NPSH) is less than (NPSH) , then suggest corrective action to make R A R (NPSH) greater than (NPSH) . A R
[7 marks]