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Topic: Will an eccentric (off-center) shaft mixer without baffles work?

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We have a double jacket mixer (height 2.52 m  and diameter 2.25 m) with eccentric shaft and it has no baffles. We need to use it for mixing liquid detergent with viscosity from 1000 to 6000. My questions are: Is it suitable for such process? (I mean with eccentric shaft). What are the suitable blade types? And what is the driving motor power needed?
  • Avatar Dave Dickey Forum Moderator 286 Posts

    Re: Will an eccentric (off-center) shaft mixer without baffles work?

    An eccentric (off-center) shaft mixer without baffles should work because of the moderately high viscosity of the liquid detergent.  Higher viscosities reduce the need for baffles, because the resistance at the tank wall will restrict the amount of swirling (rotational) motion in the tank.
     
    The best impeller design for this situation requires two (2) pitched-blade turbines, each with 4 blades at 45 degree angles.  Each impeller should be 0.6 meters in diameter.  The two impellers should be about 0.6 meters and 1.6 meters off the bottom.  The mixer needs to rotate at 100 rpm and will require a 3.73 KW motor.  Try not to deviate from these recommendations.  Other combinations of impeller diameter and rotational speed will work, but only if changes are made to keep the power and intensity approximately the same as this recommendation.

    The answers by this expert are based on the best available interpretation of the information provided.  The consequences of the application of this information are the responsibility of the user.  If clarification is needed, please submit a further question.

  • Avatar oluwadara olayinka Community Member 1 Post

    Re: Will an eccentric (off-center) shaft mixer without baffles work?

    what is the best mixer design for alum tank 2.7 meters high and diameter is 7meters i will appreciate a better tank dimension suggestion and mixer design for 100,000 litres of alluminium sulphate (dissolved alum)
  • Avatar Dave Dickey Forum Moderator 286 Posts

    Re: Will an eccentric (off-center) shaft mixer without baffles work?

    The alum tank described in this application is a large diameter, sort height tank that is typically mixed with a side-entry mixer.  For a low viscosity, solution of aluminum sulfate, a side-entry mixer should be more than adequate to move and blend the contents.  A 2.2 KW side-entry mixer running at 350 rpm with a 0.45m diameter wide-blade hydrofoil (propeller equivalent) impeller should work.  The liquid level should not drop below about 1.5 meters, otherwise the mixer will draw in air, which will cause damaging vibrations.