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- Question
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
- Correct Answer
- Crystal and precipitates are not too small, so as to ensure easy separation of the solids from the mother liquor
- 1. 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
- 2. 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
- 3. Power number is expressed as
Options- A. P0 / N2Di3?
- B. P0 / N3Di5?
- C. P0 / N3Di3?
- D. P0 / N2Di2? Discuss
- 4. The oxygen transfer rate in a bioreactor will increase if
Options- A. oil is added
- B. antifoam is added
- C. detergent like molecules are added
- D. increase in the reactor temperature Discuss
- 5. At 25°C, the saturation concentration of oxygen in water is 1.26 mmol/l and the partial pressure of oxygen is 1 atm. The Henry's law constant will be
Options- A. 0.793atml/mmol
- B. 0.207atml/mmol
- C. 1.26 atml/mmol
- D. 8.74 atml/mmol Discuss
- 6. 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
- 7. 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
- 8. 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
- 9. 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
- 10. 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
Agitation and Aeration problems
Search Results
Correct Answer: measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor
Correct Answer: All of the above
Correct Answer: P0 / N3Di5?
Correct Answer: detergent like molecules are added
Correct Answer: 0.793atml/mmol
Correct Answer: 1 : 1
Correct Answer: imposed forced to intertial force
Correct Answer: all of the above
Correct Answer: to ensure that the bulk of the energy consumption occurs at the blades
Correct Answer: All of the above
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