Top Entry Mixers

Fluid mixing applications are primarily divided into 3 main categories:

 

Afromix Agitators clip image006

  • Flow sensitive applications
  • Gas Dispersions
  • Chemical Reactions

Often processes are a combination of all three. However, while flow sensitive applications form 90% of all processing duties, including Leaching, CIP, CIL, Crude oil storage, Pulp Mixing etc, the section of the market involving the largest agitators is generally gas dispersion. Chemical reactions can require either Flow producing, or Gas dispersing, impellers.

 

 

Autoclaves and High Pressure Units

CausticAutoclave new logo resised

The design of Autoclave agitators requires knowledge of the operating condition of the autoclave, the production rate, calculation of the extreme forces acting on the agitator and drive, the limits and tolerances of high pressure mechanical seals, the design of high pressure flanges and the requirements for materials of construction.

This knowledge is most useful when it comes from a working relationship between the client and the agitator supplier.

AFX have design programmes incorporating the experience ,gathered over 35 years in the industry, to ensure reliable, well engineered, agitators for High Pressure applications.

Pedestals and bearing members are often manufactured in Stainless Steel, a very cost effective alternative to Mild Steel.

 

 

 

 

 

Gas Dispersion

BIOX Render 03Gas despersion

Gas dispersion applications include:

  • BIO-oxidation processes (Bacterial Leaching)
  • Fermentation and Hydrogenation
  • Iron Removal
  • Cyanide Detox

In these processes, large volumes of gas are injected into the vessel/reactor – through some type of dispersion unit, be it a sparge ring or pipe.  Impellers for these applications need to be carefully selected to prevent flooding of the impeller, by the air, and to ensure effective dispersion, blending and solids suspension.The mechanical design of these systems is often complex, with the agitators “seeing” large fluid forces and consequential shaft deflection. AFX have extensive experience in the process and mechanical design of these agitators.The impeller of choice is the AFX high solidity P4 impeller, providing efficient operation at high gas induction rates.

 

 Top Entry Mixers          

Top Entry new logoIn applications where bending moment does not dominate the design of the agitators, gearboxes are selected to withstand the Torque, Bending and Thrust requirements of the agitator. In these installations, agitators are provided with robust, machined, mounting bases.  These bases are machined top and bottom to ensure accurate alignment of the gearbox with the base – and the base with the mounting structure. Gearbox cracking and bearing failure can often be attributed to poor gearbox mounting and alignment.

The AFX mounting base design eliminates these problems.

 

 

 

 

Small Top Entry Fixed Mount and Portable Mixers

Portable new logoAFX’s main market is the supply of large agitators for a variety of processing duties, in a wide range of industries. However, there is still strong need for small, fixed and portable mount agitators up to 5.5 kW.  AFX manufacturers a range of these units including:

  • Portable units for clamping to the wall of mixing vessels.
  • Wall mounted units for use with multiple containers.
  • Fixed mounted, angular offset units for use in unbaffled mixing vessels.
  • Centrally mounted units, either flange or beam mounted, for use in baffled vessels.

 

 

 

 

 

Large Top Entry Mixers

AMX7500Mixer large top entry mixerAs the processing demands of industry are increasing, the requirement for large Top entry agitators is becoming the norm, rather than the unusual.  This is particularly true in  the Minerals Processing industry. Recent applications require the  installation of agitators with 18m long overhung, unsupported shafts , impellers in excess of 6,5 m diameter, and drives exceeding 300kW. For these agitators, reliable mechanical design is the driving requirement. Designing agitators of this size requires an accurate prediction of peak and fluctuating forces operating on the impeller system, the design limitations of the gearboxes, and the strength of the in-tank components. AFX make extensive use of Finite Element Analysis (F.E.A) to analyze these loads and forces and their effect on the size and reliability of the designs. AFX use FEA during the design stage, believing that this sophisticated technique should be used to predict problems before they occur – not used to solve problems afterwards.

 

 

 

 

Pedestal Mounted Mixers

108 new logoThe design of large top entry agitators is often driven more by the requirement for the gearboxes to withstand high bending moments as opposed to a requirement for high torque.  As the gearboxes are always limited by torque – and output shaft size selected accordingly, high bending moments often dictate the selection of larger gearboxes. For these applications, AFX uses independent bearing members. This design allows the gearbox to be selected on the torque requirements only, while the independent bearing member accommodates the highloads produced by the agitator, in terms of thrust and bending. These pedestals or bearing members are carefully machined in a single setting to ensure accurate alignment of intermediate shaft, gearbox and lower shaft. Special 5 axis machines are used for this purpose. Pedestals and bearing members are often manufactured in Stainless Steel, a very cost effective alternative to Mild Steel.

 

 

 

 

 

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