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Home Biochemical Engineering Agitation and Aeration Comments

  • Question
  • Radial flow impellers


  • Options
  • A. provide high shear conditions for breaking up bubbles
  • B. direct flow towards the walls of the reactor
  • C. Both (a) and (b)
  • D. provide low shear conditions and are suited for use in shear sensitive procesess

  • Correct Answer
  • Both (a) and (b) 


  • Agitation and Aeration problems


    Search Results


    • 1. 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
    • 2. 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
    • 3. 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
    • 4. 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
    • 5. 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
    • 6. What is the ratio of diameter of impeller to the diameter of tank (Da:Dt)?

    • Options
    • A. 1 : 3
    • B. 2 : 1
    • C. 4 : 1
    • D. 1 : 5
    • Discuss
    • 7. The volume of liquid (VL) in a cylindrical reactor can be calculated from the liquid height (HL) and tank diameter (Dt) using the following equation

    • Options
    • A. VL = 4/3 x ? x HL x Dt3/8
    • B. VL= HL x ? x Dt2/4
    • C. VL= HL x ? x Dt2
    • D. VL = 4 x ? x Dt2
    • Discuss
    • 8. Which of the following impellers are used for wide range of viscosities?

    • Options
    • A. paddles
    • B. turbines
    • C. propellers
    • D. none of these
    • Discuss
    • 9. The relationship between the del factor, temperature and time is given as

    • Options
    • A. ? = A.t. e-E/RT
    • B. ? = 1/(A.t. e-E/RT)
    • C. ? = A.t. eE/RT
    • D. ? = A.t.T
    • Discuss
    • 10. The specific death rate of an organism can be expressed as

    • Options
    • A. ln 2/D
    • B. D/ln2
    • C. D.ln2
    • D. 2.0.3/ln2
    • Discuss


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