Discussion
Home ‣ Biochemical Engineering ‣ Agitation and Aeration Comments
- Question
An aerated bioreactor will increase oxygen transfer rates with the addition of detergents because it
Options- A. enhances bubble coalescence
- B. causes bubbles to expand
- C. discourages bubble coalescence
- D. increases the surface tension of the liquid
- Correct Answer
- discourages bubble coalescence
- 1. Which of the following(s) is/are non-mechanically agitated reactors?
Options- A. Stirrer tank reactor
- B. Bubble column
- C. Air lift reactor
- D. Both (b) and (c) Discuss
- 2. The range of width for the baffle in the fermenter is __________ times of vessel diameter
Options- A. 1/10 to 1/12
- B. 1/8 to 1/10
- C. 1/5 to 1/8
- D. none of these Discuss
- 3. Why vortexing is undesirable in the agitation of biological systems?
Options- A. The collision between the cells, impeller and air bubbles will lead to cell damage
- B. Poor mixing despite the use of high stirrer speeds
- C. Mixing will not be in the turbulent region
- D. All of the above Discuss
- 4. The reason of using a flat disk in a Turbine is
Options- A. to create high shear conditions
- B. to break up bubbles more efficiently than the impeller blades
- C. to ensure that the bulk of the energy consumption occurs at the blades
- D. all of the above Discuss
- 5. Power consumption by agitation is
Options- A. a function of physical properties
- B. a function of operating conditions
- C. a function of vessel and impeller geometry
- D. all of the above Discuss
- 6. The average fractional gas hold up (H) can be given as (where Zf and Zl are the level of aerated and clear liquid respectively)
Options- A. H = (Zf-Zl)/Zf
- B. H = Zf/Zl
- C. H = Zf/ZfZl
- D. H =(Zf+Zl)/Zf Discuss
- 7. 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
- 8. 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
- 9. 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
- 10. 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
Agitation and Aeration problems
Search Results
Correct Answer: Both (b) and (c)
Correct Answer: 1/10 to 1/12
Correct Answer: All of the above
Correct Answer: to ensure that the bulk of the energy consumption occurs at the blades
Correct Answer: all of the above
Correct Answer: H = (Zf-Zl)/Zf
Correct Answer: Both (a) and (b)
Correct Answer: axial flow impeller
Correct Answer: Calderbank and Moo-Young theory
Correct Answer: the partial pressure of oxygen and the saturation concentration of oxygen in the liquid
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