Code No: R05310804 R05 Set No. 2
III B.Tech I Semester Supplementary Examinations,June 2010
MASS TRANSFER OPERATIONS-I Chemical Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Write short note on ‘Sparged Vessels’.
(b) Classify gas-liquid contact devices. [8+8]
2. (a) Describe the basic differences between Film Theory, Penetration Theory and
Film-surface renewal theory.
(b) Write short notes on analogies between heat and mass transfer. [8+8]
3. A feed mixture composed of 42mole% heptane and 58 mole% ethyl benzene is to be fractionated at 760 mm of Hg to produce a distillate containing 97% mole heptane and a residue containing 99% mole ethyl benzene. Assuming feed to be saturated liquid calculate:
(a) Minimum reflux ratio
(b) The heat load on condenser and reboiler in Kcal/hr for a feed rate of 5000Kg/hr. (c) Number of stages if actual reflux ratio is 1.4 times the minimum.
Vapour- liquid equilibrium and enthalpy data for heptane-ethyl benzene at 760 mm
Hg. [16]
| t 0C | x(%mole) | y(%mole) | Hl Kcal/Kg mole | Hg Kcal/Kg mole |
| 136.2 | 0.0 | 0.0 | 5920 | 14520 |
| 129.5 | 8.0 | 23.3 | 5697 | 14203 |
| 122.9 | 18.5 | 42.8 | 5520 | 13920 |
| 119.7 | 25.1 | 51.4 | 5440 | 13870 |
| 116.0 | 33.5 | 60.8 | 5360 | 13610 |
| 110.8 | 48.7 | 72.9 | 5260 | 13450 |
| 106.2 | 65.1 | 83.4 | 5170 | 13110 |
| 103.0 | 78.8 | 90.4 | 5160 | 12940 |
| 100.2 | 91.4 | 96.3 | 5124 | 12784 |
| 98.5 | 100.0 | 100.0 | 5100 | 12675 |
4. A ten-plate distillation column with re-boiler and total condenser is available for use. An equimolar mixture of A and B at its boiling point is to be separated to get a distillate containing 90% A (mole%). The relative volatility of mixture is 2.6. Calculate:
(a) Minimum reflux ratio.
1
Code No: R05310804 R05 Set No. 2
(b) The yield of distillate and residue for R = 1.2. [16]
5. (a) Explain briefly Absorption and Stripping.
(b) Explain briefly Thermal diffusion and Sweep diffusion with suitable examples. [8+8]
6. (a) How does the binary gas-phase diffusivity depend upon the total pressure and temperature? Explain qualitatively.
(b) In a laboratory 3×10−4 m3 of toluene was accidentally spilled over and has quickly spread over an area of 0.85 m2. If the diffusion is taking place through a stagnant air of 1 mm thick, calculate the time required for the toluene to evaporate completely at 298 K and 1.013×105 N/m2 For toluene, at prevailing conditions, density is 866 kg/m3 ,diffusivity in air is 8.4×10−6 m2 /sec and vapor pressure is 3.99966×103 N/m2. [8+8]
7. (a) Jasmone is a high-value product used in perfumery and cosmetic industries.
A suspension of jasmine flowers in water is contacted with an organic solvent to recover the compound. During extraction, the compound diffuses from the aqueous phase to the dispersed organic phase. The individual mass transfer coefficients are 3.5×10−6 cm/s (organic phase) and 2.7×10−5 cm/s (aqueous phase). The solute is 175 times more soluble in the organic phase (y = 175x; y = mole fraction of the solute in the organic phase). The aqueous solution is dilute and the total molar concentration of the organic phase is 10 kmol/m3. Calculate the overall mass transfer coefficient Ky . Which phase resistance controls?
(b) Explain briefly two film theory with neat sketch. [8+8]
8. (a) A mixture of benzene and p-xylene is batch distilled at atmospheric pressure.
The rate of heat input to the still is 4000 kcal/h. Individual heats of vapor- ization are: benzene = 100 kcal/kg, p-xylene = 85 kcal /kg, and the relative volatility of benzene in the mixture is 5.6. Calculate the instantaneous rate of vaporization of p-xylene when the liquid in the still has 40 mole% benzene in it.
(b) Derive Rayleigh’s equation and mention assumptions made. [6+10]
? ? ? ? ?
2
Code No: R05310804 R05 Set No. 4
III B.Tech I Semester Supplementary Examinations,June 2010
MASS TRANSFER OPERATIONS-I Chemical Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. A feed mixture composed of 42mole% heptane and 58 mole% ethyl benzene is to be fractionated at 760 mm of Hg to produce a distillate containing 97% mole heptane and a residue containing 99% mole ethyl benzene. Assuming feed to be saturated liquid calculate:
(a) Minimum reflux ratio
(b) The heat load on condenser and reboiler in Kcal/hr for a feed rate of 5000Kg/hr. (c) Number of stages if actual reflux ratio is 1.4 times the minimum.
Vapour- liquid equilibrium and enthalpy data for heptane-ethyl benzene at 760 mm
Hg. [16]
| t 0C | x(%mole) | y(%mole) | Hl Kcal/Kg mole | Hg Kcal/Kg mole |
| 136.2 | 0.0 | 0.0 | 5920 | 14520 |
| 129.5 | 8.0 | 23.3 | 5697 | 14203 |
| 122.9 | 18.5 | 42.8 | 5520 | 13920 |
| 119.7 | 25.1 | 51.4 | 5440 | 13870 |
| 116.0 | 33.5 | 60.8 | 5360 | 13610 |
| 110.8 | 48.7 | 72.9 | 5260 | 13450 |
| 106.2 | 65.1 | 83.4 | 5170 | 13110 |
| 103.0 | 78.8 | 90.4 | 5160 | 12940 |
| 100.2 | 91.4 | 96.3 | 5124 | 12784 |
| 98.5 | 100.0 | 100.0 | 5100 | 12675 |
2. (a) A mixture of benzene and p-xylene is batch distilled at atmospheric pressure.
The rate of heat input to the still is 4000 kcal/h. Individual heats of vapor- ization are: benzene = 100 kcal/kg, p-xylene = 85 kcal /kg, and the relative volatility of benzene in the mixture is 5.6. Calculate the instantaneous rate of vaporization of p-xylene when the liquid in the still has 40 mole% benzene in it.
(b) Derive Rayleigh’s equation and mention assumptions made. [6+10]
3. (a) How does the binary gas-phase diffusivity depend upon the total pressure and temperature? Explain qualitatively.
(b) In a laboratory 3×10−4 m3 of toluene was accidentally spilled over and has quickly spread over an area of 0.85 m2. If the diffusion is taking place through a stagnant air of 1 mm thick, calculate the time required for the toluene to
3
Code No: R05310804 R05 Set No. 4
evaporate completely at 298 K and 1.013×105 N/m2 For toluene, at prevailing conditions, density is 866 kg/m3 ,diffusivity in air is 8.4×10−6 m2 /sec and vapor pressure is 3.99966×103 N/m2. [8+8]
4. (a) Describe the basic differences between Film Theory, Penetration Theory and
Film-surface renewal theory.
(b) Write short notes on analogies between heat and mass transfer. [8+8]
5. A ten-plate distillation column with re-boiler and total condenser is available for use. An equimolar mixture of A and B at its boiling point is to be separated to get a distillate containing 90% A (mole%). The relative volatility of mixture is 2.6. Calculate:
(a) Minimum reflux ratio.
(b) The yield of distillate and residue for R = 1.2. [16]
6. (a) Explain briefly Absorption and Stripping.
(b) Explain briefly Thermal diffusion and Sweep diffusion with suitable examples. [8+8]
7. (a) Write short note on ‘Sparged Vessels’.
(b) Classify gas-liquid contact devices. [8+8]
8. (a) Jasmone is a high-value product used in perfumery and cosmetic industries.
A suspension of jasmine flowers in water is contacted with an organic solvent to recover the compound. During extraction, the compound diffuses from the aqueous phase to the dispersed organic phase. The individual mass transfer coefficients are 3.5×10−6 cm/s (organic phase) and 2.7×10−5 cm/s (aqueous phase). The solute is 175 times more soluble in the organic phase (y = 175x; y = mole fraction of the solute in the organic phase). The aqueous solution is dilute and the total molar concentration of the organic phase is 10 kmol/m3. Calculate the overall mass transfer coefficient Ky . Which phase resistance controls?
(b) Explain briefly two film theory with neat sketch. [8+8]
? ? ? ? ?
4
Code No: R05310804 R05 Set No. 1
III B.Tech I Semester Supplementary Examinations,June 2010
MASS TRANSFER OPERATIONS-I Chemical Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Explain briefly Absorption and Stripping.
(b) Explain briefly Thermal diffusion and Sweep diffusion with suitable examples. [8+8]
2. (a) A mixture of benzene and p-xylene is batch distilled at atmospheric pressure.
The rate of heat input to the still is 4000 kcal/h. Individual heats of vapor- ization are: benzene = 100 kcal/kg, p-xylene = 85 kcal /kg, and the relative volatility of benzene in the mixture is 5.6. Calculate the instantaneous rate of vaporization of p-xylene when the liquid in the still has 40 mole% benzene in it.
(b) Derive Rayleigh’s equation and mention assumptions made. [6+10]
3. A ten-plate distillation column with re-boiler and total condenser is available for use. An equimolar mixture of A and B at its boiling point is to be separated to get a distillate containing 90% A (mole%). The relative volatility of mixture is 2.6. Calculate:
(a) Minimum reflux ratio.
(b) The yield of distillate and residue for R = 1.2. [16]
4. A feed mixture composed of 42mole% heptane and 58 mole% ethyl benzene is to be fractionated at 760 mm of Hg to produce a distillate containing 97% mole heptane and a residue containing 99% mole ethyl benzene. Assuming feed to be saturated liquid calculate:
(a) Minimum reflux ratio
(b) The heat load on condenser and reboiler in Kcal/hr for a feed rate of 5000Kg/hr. (c) Number of stages if actual reflux ratio is 1.4 times the minimum.
Vapour- liquid equilibrium and enthalpy data for heptane-ethyl benzene at 760 mm
Hg. [16]
5
Code No: R05310804 R05 Set No. 1
| t 0C | x(%mole) | y(%mole) | Hl Kcal/Kg mole | Hg Kcal/Kg mole |
| 136.2 | 0.0 | 0.0 | 5920 | 14520 |
| 129.5 | 8.0 | 23.3 | 5697 | 14203 |
| 122.9 | 18.5 | 42.8 | 5520 | 13920 |
| 119.7 | 25.1 | 51.4 | 5440 | 13870 |
| 116.0 | 33.5 | 60.8 | 5360 | 13610 |
| 110.8 | 48.7 | 72.9 | 5260 | 13450 |
| 106.2 | 65.1 | 83.4 | 5170 | 13110 |
| 103.0 | 78.8 | 90.4 | 5160 | 12940 |
| 100.2 | 91.4 | 96.3 | 5124 | 12784 |
| 98.5 | 100.0 | 100.0 | 5100 | 12675 |
5. (a) Jasmone is a high-value product used in perfumery and cosmetic industries.
A suspension of jasmine flowers in water is contacted with an organic solvent to recover the compound. During extraction, the compound diffuses from the aqueous phase to the dispersed organic phase. The individual mass transfer coefficients are 3.5×10−6 cm/s (organic phase) and 2.7×10−5 cm/s (aqueous phase). The solute is 175 times more soluble in the organic phase (y = 175x; y = mole fraction of the solute in the organic phase). The aqueous solution is dilute and the total molar concentration of the organic phase is 10 kmol/m3. Calculate the overall mass transfer coefficient Ky . Which phase resistance controls?
(b) Explain briefly two film theory with neat sketch. [8+8]
6. (a) Write short note on ‘Sparged Vessels’.
(b) Classify gas-liquid contact devices. [8+8]
7. (a) Describe the basic differences between Film Theory, Penetration Theory and
Film-surface renewal theory.
(b) Write short notes on analogies between heat and mass transfer. [8+8]
8. (a) How does the binary gas-phase diffusivity depend upon the total pressure and temperature? Explain qualitatively.
(b) In a laboratory 3×10−4 m3 of toluene was accidentally spilled over and has quickly spread over an area of 0.85 m2. If the diffusion is taking place through a stagnant air of 1 mm thick, calculate the time required for the toluene to evaporate completely at 298 K and 1.013×105 N/m2 For toluene, at prevailing conditions, density is 866 kg/m3 ,diffusivity in air is 8.4×10−6 m2 /sec and vapor pressure is 3.99966×103 N/m2. [8+8]
? ? ? ? ?
6
Code No: R05310804 R05 Set No. 3
III B.Tech I Semester Supplementary Examinations,June 2010
MASS TRANSFER OPERATIONS-I Chemical Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. A ten-plate distillation column with re-boiler and total condenser is available for use. An equimolar mixture of A and B at its boiling point is to be separated to get a distillate containing 90% A (mole%). The relative volatility of mixture is 2.6. Calculate:
(a) Minimum reflux ratio.
(b) The yield of distillate and residue for R = 1.2. [16]
2. (a) How does the binary gas-phase diffusivity depend upon the total pressure and temperature? Explain qualitatively.
(b) In a laboratory 3×10−4 m3 of toluene was accidentally spilled over and has quickly spread over an area of 0.85 m2. If the diffusion is taking place through a stagnant air of 1 mm thick, calculate the time required for the toluene to evaporate completely at 298 K and 1.013×105 N/m2 For toluene, at prevailing conditions, density is 866 kg/m3 ,diffusivity in air is 8.4×10−6 m2 /sec and vapor pressure is 3.99966×103 N/m2. [8+8]
3. (a) Describe the basic differences between Film Theory, Penetration Theory and
Film-surface renewal theory.
(b) Write short notes on analogies between heat and mass transfer. [8+8]
4. (a) A mixture of benzene and p-xylene is batch distilled at atmospheric pressure.
The rate of heat input to the still is 4000 kcal/h. Individual heats of vapor- ization are: benzene = 100 kcal/kg, p-xylene = 85 kcal /kg, and the relative volatility of benzene in the mixture is 5.6. Calculate the instantaneous rate of vaporization of p-xylene when the liquid in the still has 40 mole% benzene in it.
(b) Derive Rayleigh’s equation and mention assumptions made. [6+10]
5. (a) Jasmone is a high-value product used in perfumery and cosmetic industries.
A suspension of jasmine flowers in water is contacted with an organic solvent to recover the compound. During extraction, the compound diffuses from the aqueous phase to the dispersed organic phase. The individual mass transfer coefficients are 3.5×10−6 cm/s (organic phase) and 2.7×10−5 cm/s (aqueous phase). The solute is 175 times more soluble in the organic phase (y = 175x; y = mole fraction of the solute in the organic phase). The aqueous solution is dilute and the total molar concentration of the organic phase is 10 kmol/m3. Calculate the overall mass transfer coefficient Ky . Which phase resistance controls?
7
Code No: R05310804 R05 Set No. 3
(b) Explain briefly two film theory with neat sketch. [8+8]
6. (a) Explain briefly Absorption and Stripping.
(b) Explain briefly Thermal diffusion and Sweep diffusion with suitable examples. [8+8]
7. A feed mixture composed of 42mole% heptane and 58 mole% ethyl benzene is to be fractionated at 760 mm of Hg to produce a distillate containing 97% mole heptane and a residue containing 99% mole ethyl benzene. Assuming feed to be saturated liquid calculate:
(a) Minimum reflux ratio
(b) The heat load on condenser and reboiler in Kcal/hr for a feed rate of 5000Kg/hr. (c) Number of stages if actual reflux ratio is 1.4 times the minimum.
Vapour- liquid equilibrium and enthalpy data for heptane-ethyl benzene at 760 mm
Hg. [16]
| t 0C | x(%mole) | y(%mole) | Hl Kcal/Kg mole | Hg Kcal/Kg mole |
| 136.2 | 0.0 | 0.0 | 5920 | 14520 |
| 129.5 | 8.0 | 23.3 | 5697 | 14203 |
| 122.9 | 18.5 | 42.8 | 5520 | 13920 |
| 119.7 | 25.1 | 51.4 | 5440 | 13870 |
| 116.0 | 33.5 | 60.8 | 5360 | 13610 |
| 110.8 | 48.7 | 72.9 | 5260 | 13450 |
| 106.2 | 65.1 | 83.4 | 5170 | 13110 |
| 103.0 | 78.8 | 90.4 | 5160 | 12940 |
| 100.2 | 91.4 | 96.3 | 5124 | 12784 |
| 98.5 | 100.0 | 100.0 | 5100 | 12675 |
8. (a) Write short note on ‘Sparged Vessels’.
(b) Classify gas-liquid contact devices. [8+8]
? ? ? ? ?
8
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