Discussion
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- Question
A flooded impeller will lead to poor oxygen transfer rates because
Options- A. bubbles tend to coalesce under the impeller
- B. bubbles tend to break down too rapidly under high shear conditions
- C. bubbles tend to move too quickly through the bulk liquid
- D. the cells clog up the surface of the bubble
- Correct Answer
- bubbles tend to coalesce under the impeller
- 1. Transient flow range of mixing speed is obtained for
Options- A. Rei<10
- B. 10<Rei<104
- C. Rei>104
- D. None of these Discuss
- 2. Henry's law relates
Options- A. the partial pressure of oxygen and the saturation concentration of oxygen in the liquid
- B. the oxygen transfer rate and the bubble size
- C. the oxygen transfer rate and the temperature
- D. the oxygen transfer rate to the partial pressure of oxygen in the liquid Discuss
- 3. Which of the following is not considered among the three best-known theories of interphase mass transfer?
Options- A. two-film theory
- B. penetration theory
- C. surface renewal theory
- D. Calderbank and Moo-Young theory Discuss
- 4. A typical ceiling fan would be best described as a(n)
Options- A. radial flow impeller
- B. axial flow impeller
- C. intermig impeller
- D. Rushton turbine Discuss
- 5. Vortexing in stirred tank reactors can be prevented by
Options- A. installing baffles in the reactor
- B. shifting the impeller to an off-centre position
- C. Both (a) and (b)
- D. using axial flow impellers Discuss
- 6. Turbine impeller consists of flat impeller blades with
Options- A. a vertical pitch welded directly to the shaft
- B. a angled pitch welded directly to the shaft
- C. a vertical pitch welded to a horizontal disk
- D. a angled pitch welded to a horizontal disk Discuss
- 7. The power consumption in a stirring vessel can be assessed by using a
Options- A. dynamometer
- B. strain gauge attached to agitator shaft
- C. watt meter attached to agitator motor
- D. all of these Discuss
- 8. The rate limiting step in the movement of oxygen from the gas phase in a bubble to the cell is the movement of oxygen molecules through
Options- A. gas-liquid interface
- B. bubble boundary layer
- C. bulk liquid
- D. gas phase Discuss
- 9. Swirling and vortex formation can be prevented by
Options- A. using baffles
- B. using diffusion ring with turbines
- C. both (a) and (b)
- D. none of these Discuss
- 10. Gas hold up, characterizing the hydrodynamics in a fermenter, mainly depends on the
Options- A. superficial gas velocity
- B. power consumption
- C. Both (a) and (b)
- D. gas concentration Discuss
Agitation and Aeration problems
Search Results
Correct Answer: 10<Rei<104
Correct Answer: the partial pressure of oxygen and the saturation concentration of oxygen in the liquid
Correct Answer: Calderbank and Moo-Young theory
Correct Answer: axial flow impeller
Correct Answer: Both (a) and (b)
Correct Answer: a vertical pitch welded to a horizontal disk
Correct Answer: all of these
Correct Answer: bubble boundary layer
Correct Answer: both (a) and (b)
Correct Answer: Both (a) and (b)
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