Discussion
Home ‣ Biochemical Engineering ‣ Agitation and Aeration Comments
- Question
In the design of a paddle agitator, the ratio of paddle diameter to tank diameter is normally taken as
Options- A. 0.1
- B. 0.8
- C. 0.25
- D. 0.5
- Correct Answer
- 0.8
- 1. Higher temperatures affect oxygen transfer rates by
Options- A. increasing KLa but lowering C*o
- B. lowering KLa but increasing C*o
- C. increasing KLa and increasing Co
- D. lowering KLa and lowering Co Discuss
- 2. Which of the following model holds correct for the two-film theory? (where KL is the mass transfer coefficient, DAB diffusivity and Zf film thickness)
Options- A. KL = DAB/Zf
- B. KL = DAB
- C. KL = Zf/DAB
- D. KL = DAB.Zf Discuss
- 3. A microbial population in a suspension culture will only be limited by oxygen availability if the dissolved oxygen
Options- A. concentration is less than the critical concentration
- B. concentration is greater than the critical concentration
- C. levels are greater than the saturation concentration of oxygen
- D. levels are equal to saturation oxygen level Discuss
- 4. Small propellers turn at the speed of either
Options- A. 20 or 150 rpm
- B. 150 or 300 rpm
- C. 400 or 800 rpm
- D. 1150 rpm or 1750 rpm Discuss
- 5. Main reason for using baffles in stirred tank reactors are
Options- A. baffles permit turbulence conditions to arise at low stirrer speed
- B. baffles will allow axial mixing to occur even with radial flow impellers
- C. both (a) and (b)
- D. baffles prevent turbulent conditions in stirred tank reactors Discuss
- 6. The maximum solubility of the alkane in the medium is 5 ppm. If the actual dissolved concentration of the alkane in the medium is 1 ppm. what conclusion may be drawn?
Options- A. The growth rate is limited by the rate of mass transfer of the alkane into the fermentation medium
- B. The growth rate is limited by the intrinsic kinetic properties of the cells and not by mass transfer
- C. The growth rate is neither mass transfer nor kinetically limited
- D. No conclusion on the growth rate can be withdrawn Discuss
- 7. The power required by an impeller in a gas sparged system compare to the power required by impeller operating at same speed in a gas free liquid is usually
Options- A. lesser
- B. higher
- C. same
- D. may be lesser or higher depending upon the geometry Discuss
- 8. The oxygen absorption rate can be determined by
Options- A. sodium sulfite oxidation method
- B. dynamic gassing out technique
- C. direct measurement
- D. all of these Discuss
- 9. Which of the following is not classified as an axial flow impeller?
Options- A. A propeller
- B. A marine impeller
- C. A Rushton turbine
- D. A hydrofoil impeller Discuss
- 10. The Intermig impeller is
Options- A. an axial flow impeller which can be used for the culture of aerobic organisms
- B. directed upwards rather than towards the base of the reactor
- C. a fork shaped extensions to the impeller facilitate bubble break up
- D. All of the above Discuss
Agitation and Aeration problems
Search Results
Correct Answer: increasing KLa but lowering C*o
Correct Answer: KL = DAB/Zf
Correct Answer: concentration is less than the critical concentration
Correct Answer: 1150 rpm or 1750 rpm
Correct Answer: both (a) and (b)
Correct Answer: No conclusion on the growth rate can be withdrawn
Correct Answer: lesser
Correct Answer: all of these
Correct Answer: A Rushton turbine
Correct Answer: All of the above
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