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Home ‣ Biochemical Engineering ‣ Agitation and Aeration Comments
- Question
Which of the following impeller is used in situation where strong vertical currents are desirable for suspending heavily particles?
Options- A. Propeller
- B. Paddle
- C. Turbine
- D. None of these
- Correct Answer
- Propeller
- 1. If the stirring speed increased from 300 to 500 rpm leads to an increase in the reaction rate by two folds. Then it may be concluded that
Options- A. the reaction was mass transfer limited at 300 rpm
- B. the reaction was mass transfer limited at 500 rpm
- C. the reaction did not involve any mass transfer step
- D. the movement of molecules in the reactor at 300 rpm occurred due to diffusion alone Discuss
- 2. Axial flow impellers
Options- A. provide high shear conditions for breaking up bubbles
- B. provide low shear conditions and are suited for use in shear sensitive procesess
- C. provide direct flow towards the walls of the reactor
- D. none of the above Discuss
- 3. Which device is commonly used for measuring the rate of rotation (rpm) of the stirrer shaft?
Options- A. Anemometer
- B. Manometer
- C. Tachometer
- D. Barometer Discuss
- 4. Turbulent flow range of mixing speed is obtained for
Options- A. Rei<10
- B. 10<Rei<104
- C. Rei>104
- D. None of these Discuss
- 5. Bioreactors, where vortex is formed, another dimensionless number, __________ is useful.
Options- A. Stanton
- B. Rayleigh
- C. Bond
- D. Froude Discuss
- 6. Which of the following number is calculated from the diameter and peripheral speed of the impeller?
Options- A. Reynolds number
- B. Froude number
- C. Power number
- D. None of these Discuss
- 7. The main function of the dimples provided in the cooling jacket is to
Options- A. increase the level of turbulence of the cooling water in the jacket
- B. increase the residence time of the cooling water in the jacket
- C. increase the cooling water-jacket wall boundary layer size
- D. all of the above Discuss
- 8. 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
- 9. 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
- 10. 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
Agitation and Aeration problems
Search Results
Correct Answer: the reaction was mass transfer limited at 300 rpm
Correct Answer: provide low shear conditions and are suited for use in shear sensitive procesess
Correct Answer: Tachometer
Correct Answer: Rei>104
Correct Answer: Froude
Correct Answer: Reynolds number
Correct Answer: increase the level of turbulence of the cooling water in the jacket
Correct Answer: higher at the base of the reactor
Correct Answer: highest at the base of the reactor
Correct Answer: all of the above
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