Agitation and Aeration problems
- 1. Which of the following impellers will provide radial flow?
Options- A. Paddles
- B. Flat blade turbines
- C. Disk flat blade turbines
- D. All of the above Discuss
Correct Answer: All of the above
- 2. The average concentration of oxygen in the boundary layers surrounding the bubbles (Co*) in a reactor is normally determined by
Options- A. ultra-small dissolved oxygen probes
- B. laser based photographic systems
- C. measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor
- D. measuring the steady state concentration of oxygen in the bulk liquid after inoculation of the reactor Discuss
Correct Answer: measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor
- 3. Which of the following best explains the reasons for using axial flow impellers in crystallization and precipitation reactions?
Options- A. Crystal and precipitates are not too small, so as to ensure easy separation of the solids from the mother liquor
- B. Crystals and precipitates are thoroughly broken down, so as to ensure easy separation of the solids from the mother liquor
- C. Both (a) and (b)
- D. Axial flow impellers provide low shear, energy efficient mixing conditions Discuss
Correct Answer: Crystal and precipitates are not too small, so as to ensure easy separation of the solids from the mother liquor
- 4. What is the ratio of depth of liquid in vessel to the diameter of tank (H:Dt)?
Options- A. 1 : 1
- B. 2 : 1
- C. 4 : 1
- D. none of these Discuss
Correct Answer: 1 : 1
- 5. Power number is ratio of
Options- A. imposed forced to intertial force
- B. bouyant force to inertial force
- C. gravitation force to inertial force
- D. imposed force to gravitational force Discuss
Correct Answer: imposed forced to intertial force
- 6. Power consumption by agitation is
Options- A. a function of physical properties
- B. a function of operating conditions
- C. a function of vessel and impeller geometry
- D. all of the above Discuss
Correct Answer: all of the above
- 7. The reason of using a flat disk in a Turbine is
Options- A. to create high shear conditions
- B. to break up bubbles more efficiently than the impeller blades
- C. to ensure that the bulk of the energy consumption occurs at the blades
- D. all of the above Discuss
Correct Answer: to ensure that the bulk of the energy consumption occurs at the blades
- 8. 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
Correct Answer: All of the above
- 9. 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
Correct Answer: 1/10 to 1/12
- 10. 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
Correct Answer: Both (b) and (c)
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