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- Question
Power number (Np) is also known as
Options- A. Froude's number
- B. Bond's number
- C. Newton's number
- D. Rayleigh's number
- Correct Answer
- Newton's number
- 1. When the height of an aerated bioreactor is increased, it will increase the oxygen transfer rate by
Options- A. increasing the partial pressure of oxygen at the base of the reactor
- B. decreasing the saturation concentration of oxygen in the reactor
- C. decreasing the gas-holdup
- D. all of the above Discuss
- 2. A cylindrical reactor has a liquid volume of 100,000 litres. It has an aspect ratio the ratio of the channel height to width of 1:1. The height of the liquid in the reactor will be approximately:
Options- A. 1.0 m
- B. 3.0 m
- C. 5.0 m
- D. 7.0 m Discuss
- 3. During aeration, a cylindrical reactor had a height of 10 m. Without aeration, the height was 7.5 m. Under these aeration and mixing conditions, the gas hold up in the reactor is
Options- A. 100%
- B. 75%
- C. 50%
- D. 25% Discuss
- 4. The dynamic technique is based on the
Options- A. oxygen material balance in an aerated batch fermenter during the growth of microorganisms
- B. change of the oxygen concentration
- C. oxidation of the sodium sulfite to sodium sulfate
- D. oxygen material balance in a fermenter Discuss
- 5. The addition of antifoams to an aerated bioreactor will decrease oxygen transfer rates because antifoams
Options- A. increase the tendency of bubbles to coalesce
- B. tend to accumulate in the gas liquid interface
- C. reduce the surface tension of the liquid
- D. All of the above answers Discuss
- 6. Which of the following would be best described as a radial flow impeller?
Options- A. An impeller with blades pitched at 45° to the vertical
- B. A Rushton turbine
- C. Both (a) and (b)
- D. An impeller which directs liquid flow towards the base of the reactor Discuss
- 7. 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
- 8. 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
- 9. 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
- 10. 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
Agitation and Aeration problems
Search Results
Correct Answer: increasing the partial pressure of oxygen at the base of the reactor
Correct Answer: 5.0 m
Correct Answer: 25%
Correct Answer: oxygen material balance in an aerated batch fermenter during the growth of microorganisms
Correct Answer: All of the above answers
Correct Answer: A Rushton turbine
Correct Answer: both (a) and (b)
Correct Answer: 1150 rpm or 1750 rpm
Correct Answer: concentration is less than the critical concentration
Correct Answer: KL = DAB/Zf
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