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Mixing in the right cycles is important when discussing the most suitable Agitator for your Vessel

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There any many options to think about when looking to install, or retrofit, an Agitator into a new or existing application. Stephen Price has shared some key points below which will guide you through the options and reasons behind selecting the right Agitator for your application.

Let’s get started.

  • Do you require agitation in your tank?
  • Does your existing tank Agitator provide the best Agitation for your process?
  • Does your existing Agitator provide an energy-efficient solution?
  • Is your Agitator easily maintainable?

If you complete any of the following processes it may be beneficial to have a Tank Mounted Agitator:

  • Liquid blending.
  • Dissolving powders or crystals.
  • If you are preventing media from separating or looking to maintain a homogenous media.
  • Create or maintain suspension of particles.
  • Fermentation.
  • Heat transfer, heating or cooling.
    Break coagulation.

Why choose an Alfa Laval EnSaFoil Agitator

  • The energy saving impeller requires minimal energy input from the drive unit to provide the required level of agitation.
  • Gentle agitation.
  • Hight flow rate with constant pumping action across the complete diameter of the Impeller at all speeds
  • Modular construction providing a tailormade solution to suit your requirement from proven components.
  • Cleanability of the Impeller.
  • Strength of the Impeller.

Why is the EnSaFoil Impeller so special

The profiled EnSaFoil Impeller provides a constant pumping action across the complete diameter of the Impeller as shown by the blue arrows in the diagram below. 

Other Impeller designs can provide varying pumping capacities across the Impeller diameter creating possible “hot spots” in the media. As shown by the red arrows in the diagram below for a flat blade impeller with increased pumping action at the tip of the blade.

Tank Mixing
Tank Mixing

The benefits of using the Alfa Laval EnSaFoil Impeller are:

  • Ensures gentle agitation.
  • Less shear stress and shear rate in the product.
  • Less friction with the media, so less heat passed into the media.
  • Less temperature increase with agitation.
  • Less power input due to the efficiency of the EnSaFoil Impeller.

Easy Cleaning of the EnSaFoil Impeller

Due to the profiled Impeller Blade providing “splash back effect” from the upper surface to the underside of the Impeller, as shown in the diagram below, cleaning and maintenance of the blade is quick and simple.

What Flow Patterns and Agitation do Side, Top and Bottom Agitators Provide?

Side Mounted Agitator

For standard applications:

  • Agitator is mounted at a 20° downward angle, with a 5° to 7° centre offset
  • Pumping action is downwards
  • Impeller is mounted with a minimum clearance of 100mm from the bottom of the Tank.
  • The agitation / fluid flow is best suited applications to avoid media from separating and maintain a homogenous media (mainly storage tanks)
  • Normally used for low viscosity products up to 100 cP, with 500 cP being possible on special application.
  • Possible to use more that one side mounted Agitator per tank to achieve the required level of agitation.
Tank Mixing

Top and Bottom Agitators

For standard applications:

  • When Baffles are not fitted in the tank, the Agitator is mounted by an off-centre distance to prevent batch rotation of the media.
  • The off-set distance is dependant on the viscosity of the media.
  • At viscosities over 3,000 cP the Agitator can be mounted without off-set.
  • Pumping action is downwards
  • The Agitation for Top and Bottom Mounted Agitators is identical with the Impeller mounted in the same position in the tank.
  • Top Mounted Agitators have the added advantage of being to have more than one Impeller on the shaft which can be beneficial with tall tanks.
  • The Agitation / Fluid Flow is suitable for the majority of applications including:
 
    • Avoid media from separating / Maintain a homogenous media
    • Liquid blending
    • Dissolving powders or crystals
    • Create or maintain suspension of particles
    • Fermentation
    • Heat transfer, heating or cooling
    • When the agitation is to avoid media from separating / maintain a homogenous media, a Side Mounted Agitator may offer a more cost-effective solution.
Tank Mixing

In General:

  • The Impeller will be mounted ½ propeller diameter (radius) from the bottom of the tank.
  • The Impeller diameter will be approx 1/3 of the tank diameter.
  • Tip of the Impeller should have 100mm clearance to the side of the tank.
  • Tanks with a shell height greater than 4m are normally fitted with a bottom support to reduce the shaft diameter and aid shaft stiffness.
  • If media can easily foam, ensure the media covers the Impeller by ½ propeller diameter prior to operating at full speed.
  • With a height to diameter ratio of over 4:1 more than one Impeller may be required.
  • For low level agitation, low level Impellers can be added or tickler blades fitted under the main impeller.
  • Shaft mechanical seals that normally operate under the media should not be operated dry and should first be covered by the media prior to operation. During CIP, the seal should first be wetted with the CIP media prior to rotation to aid cleaning.
  • The Speed of the majority of Agitators can be adjusted with the use of a frequency inverter to obtain the most suitable agitation for the process and run the agitator slowly during the CIP cycle.
  • Normal maximum Agitator temperature for continuous operating 90° C

 

Want to know more, why not give inTank Technologies a call? We would be pleased to discuss your requirements and offer the most suitable Tank Agitator solution.

Tank Mixing

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