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Home ‣ Biochemical Engineering ‣ Agitation and Aeration Comments
- Question
The rate limiting step in the movement of oxygen from the gas phase in a bubble to the cell is the movement of oxygen molecules through
Options- A. gas-liquid interface
- B. bubble boundary layer
- C. bulk liquid
- D. gas phase
- Correct Answer
- bubble boundary layer
- 1. The power consumption in a stirring vessel can be assessed by using a
Options- A. dynamometer
- B. strain gauge attached to agitator shaft
- C. watt meter attached to agitator motor
- D. all of these Discuss
- 2. Turbine impeller consists of flat impeller blades with
Options- A. a vertical pitch welded directly to the shaft
- B. a angled pitch welded directly to the shaft
- C. a vertical pitch welded to a horizontal disk
- D. a angled pitch welded to a horizontal disk Discuss
- 3. A flooded impeller will lead to poor oxygen transfer rates because
Options- A. bubbles tend to coalesce under the impeller
- B. bubbles tend to break down too rapidly under high shear conditions
- C. bubbles tend to move too quickly through the bulk liquid
- D. the cells clog up the surface of the bubble Discuss
- 4. Transient 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. Henry's law relates
Options- A. the partial pressure of oxygen and the saturation concentration of oxygen in the liquid
- B. the oxygen transfer rate and the bubble size
- C. the oxygen transfer rate and the temperature
- D. the oxygen transfer rate to the partial pressure of oxygen in the liquid Discuss
- 6. Swirling and vortex formation can be prevented by
Options- A. using baffles
- B. using diffusion ring with turbines
- C. both (a) and (b)
- D. none of these Discuss
- 7. Gas hold up, characterizing the hydrodynamics in a fermenter, mainly depends on the
Options- A. superficial gas velocity
- B. power consumption
- C. Both (a) and (b)
- D. gas concentration Discuss
- 8. When liquid is pumped through cooling coil in a stirred tank reactor to cool. Which of the following is not correct?
Options- A. If the stirrer speed is increased, the rate will be faster
- B. Baffles in the tank will increase the rate of cooling
- C. Faster cooling rates at a slower rate of pumping
- D. Faster cooling rates at a faster rate of pumping Discuss
- 9. If liquid density and viscosity remains constant, then the Reynolds number in a stirred tank reactor will vary with the
Options- A. impeller diameter
- B. square root of the impeller diameter
- C. square of the impeller diameter
- D. cube of the impeller diameter Discuss
- 10. The oxygen uptake requirements of a microbial population is characterized by the following parameters: ?m = 0.2 h-1, K0 = 0.2 mg O2.l-1, Y0 = 0.5 mg dry weight/mg O2 and C0,crit=0.8 mg.l-1 The required concentration of cells is 1000 mg.l-1 and the saturation oxygen concentration of the medium is 5.8 mg.l-1. The required KLa must be greater than
Options- A. 64 h-1
- B. 32 h-1
- C. 16 h-1
- D. 8h-1 Discuss
Agitation and Aeration problems
Search Results
Correct Answer: all of these
Correct Answer: a vertical pitch welded to a horizontal disk
Correct Answer: bubbles tend to coalesce under the impeller
Correct Answer: 10<Rei<104
Correct Answer: the partial pressure of oxygen and the saturation concentration of oxygen in the liquid
Correct Answer: both (a) and (b)
Correct Answer: Both (a) and (b)
Correct Answer: Faster cooling rates at a slower rate of pumping
Correct Answer: square of the impeller diameter
Correct Answer: 64 h-1
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