Discussion
Home ‣ Biochemical Engineering ‣ Agitation and Aeration Comments
- Question
Which of the following impellers generate a flow parallel to the axis of shaft?
Options- A. Axial flow
- B. Radial flow
- C. Both (a)and(b)
- D. None of these
- Correct Answer
- Axial flow
- 1. For laminar flow, Reynolds number is correlated with power number as (where K, a constant which depends on the container geometry and shape of stirrer; Rei is Reynolds number for agitator; Di, stirrer diameter and N, stirrer speed)
Options- A. Np = K(Rei)-1
- B. Np = N2Di(Rei)-1
- C. Np = K(Rei)
- D. Np = KNDi(Rei)-2 Discuss
- 2. An increase in the heat transfer in the stirred tank reactor will be observed at
Options- A. higher cooling water temperature
- B. higher stirrer speed
- C. the removal of baffles from the reactor
- D. slower stirrer speed Discuss
- 3. Oxygen transfer rate is increased with an increase in the stirrer speed in aerated bioreactor because
Options- A. it decrease the bubble size
- B. it decreases the size of the boundary layer surrounding a bubble
- C. it increases the rate of movement of oxygen molecules through the bulk liquid
- D. all of the above Discuss
- 4. In a tall reactor, oxygen transfer rates will be
Options- A. highest at the surface of the reactor
- B. highest at the base of the reactor
- C. highest in the middle of the reactor
- D. the same throughout the reactor Discuss
- 5. A higher liquid height will lead to a higher gas hold up by which the oxygen transfer rate will be
Options- A. higher throughout the reactor
- B. lower throughout the reactor
- C. higher at the base of the reactor
- D. lower at the base of the reactor Discuss
- 6. What is the effect of the concentration of dissolved salts and sugars on the oxygen transfer rate?
Options- A. The saturation concentration of oxygen in the medium decreases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate
- B. The KLa of the medium decreases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate
- C. The KLa of the medium increases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate
- D. None of the above Discuss
- 7. The power required by an agitator operating in a gas-sparged system is
Options- A. lesser than the power required by an impeller in operating at same speed in a gas free system
- B. more than the power required by an impeller in operating at same speed in a gas free system
- C. same as the power required by an impeller in operating at same speed in a gas free system
- D. none of the above Discuss
- 8. Laminar flow range of mixing speed is obtained for
Options- A. Rei<10
- B. 10<Rei<104
- C. Rei>104
- D. None of these Discuss
Agitation and Aeration problems
Search Results
Correct Answer: Np = K(Rei)-1
Correct Answer: higher stirrer speed
Correct Answer: all of the above
Correct Answer: highest at the base of the reactor
Correct Answer: higher at the base of the reactor
Correct Answer: The saturation concentration of oxygen in the medium decreases with the concentration of dissolved salts and sugars, leading to a lower oxygen transfer rate
Correct Answer: lesser than the power required by an impeller in operating at same speed in a gas free system
Correct Answer: Rei<10
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