Discussion
Home ‣ Biochemical Engineering ‣ Agitation and Aeration Comments
- Question
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
- Correct Answer
- Both (a) and (b)
- 1. 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
- 2. 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 Discuss
- 3. 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
- 4. 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
- 5. 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
- 6. 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
- 7. 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
- 8. 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
- 9. 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
- 10. 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 Discuss
Agitation and Aeration problems
Search Results
Correct Answer: H = (Zf-Zl)/Zf
Correct Answer: discourages bubble coalescence
Correct Answer: Both (b) and (c)
Correct Answer: 1/10 to 1/12
Correct Answer: All of the above
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
Correct Answer: 10<Rei<104
Correct Answer: bubbles tend to coalesce under the impeller
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