Discussion
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- Question
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
- Correct Answer
- Tachometer
- 1. 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
- 2. Bioreactors, where vortex is formed, another dimensionless number, __________ is useful.
Options- A. Stanton
- B. Rayleigh
- C. Bond
- D. Froude Discuss
- 3. The effect of increasing the stirrer speed in an unbaffled stirred tank reactor is that
Options- A. a small increase in stirrer speed will cause the liquid to enter the turbulent flow regime
- B. as the stirrer speed increases, the liquid will continue to circulate and then become turbulent
- C. as the stirrer speed increases, the liquid will continue to circulate. Eventually a vortex will form.
- D. A vortex will form at low stirrer speeds. As the stirrer speed increases the liquid will start to circulate Discuss
- 4. Which of the following will have the largest interfacial area per unit volume?
Options- A. A bubble with a diameter of 1 mm
- B. A bubble with a diameter of 5 mm
- C. A bubble with a diameter of 15 mm
- D. A bubble with a diameter of 50 mm Discuss
- 5. For turbulent 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
- D. Can't be correlated Discuss
- 6. 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
- 7. 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
- 8. 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 Discuss
- 9. 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
- 10. 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
Agitation and Aeration problems
Search Results
Correct Answer: Rei>104
Correct Answer: Froude
Correct Answer: as the stirrer speed increases, the liquid will continue to circulate. Eventually a vortex will form.
Correct Answer: A bubble with a diameter of 1 mm
Correct Answer: Np = K
Correct Answer: provide low shear conditions and are suited for use in shear sensitive procesess
Correct Answer: the reaction was mass transfer limited at 300 rpm
Correct Answer: Propeller
Correct Answer: Reynolds number
Correct Answer: increase the level of turbulence of the cooling water in the jacket
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