Mixing belongs to the most important basic operations of process technology.
In nearly all processes of the chemical, mineral processing, biotechnological, food industries as well as feed stock and water treatment, mixing is undertaken with the object to accelerate the natural diffusion.
The task of an impeller consists of on the one hand to generate in the vessel a three dimensional flow field with large momentum flow density and on the other hand to create in the multi-phase system an interfacial area as large as possible. From the fluid mechanics point of view this is an extremely complex procedure. It is also the reason that although mixing is a very old process, it was until recently even with the most modern data processing systems not possible to calculate in advance the exact theoretical conditions in the agitated vessel at any given time. An optimum mixer design like Turbulator is only guaranteed if the latest scientific developments together with the operational experience are applied.
Flow Pattern and Velocity Fields
In principle the processes in agitated reactors can be related to the so-called 5 basic mixing tasks or the combination thereof:
- Suspension of solids in liquids.
- Dispersion of liquids which are not soluble in each other.
- Gassing of liquids.
- Improvement of the heat transfer.
The condition for carrying out these basic operations is that the flow relates to the whole vessel contents.
The resulting flow field depends strongly on the impeller types, their positioning and the configuration of the vessel. The first indication of the expected mixing operation in the vessel is supplied by the figure “8” flow pattern, which can be demonstrated by means of the glass vessel mixer. This figure “8” flow pattern submits initial information about the position of dead zones, internal vortices as well as the areas of strong turbulence. By observing this flow behaviour it is possible to obtain the first estimate for the expected flow field in the full scale.
However, an exact result is only obtained by direct measurements of the velocity field in all three directions (axial/radial/tangential) by means of hot wire anemometer or Laser-Doppler-technique. The analysis of the velocity field gives the distribution of the shear stress in the vessel which decisively influences the mixing process.
Whilst in the laminar area the shear stress is determined by the velocity gradients or shear gradients in the turbulent area this is insignificant because the shear stresses are exclusively caused by the turbulent fluctuating velocities.
The Rotor/Impeller has always two tasks which are:
– Circulation of the vessel volume,
– Generation of turbulence.
The Rotor/Impeller, thus, has to be simultaneously a pumping and mixing element a task which can only be solved by generating a Figure “8” flow pattern.
Turbulator™ mixing Rotor’s/Impellers are the result of continuous research and development over several years. Long operational experience with these Rotor types in nearly all industry branches very often shows clear advantages against conventional impeller configurations, for example an increase of the volume/time yield together with a reduction of mixing time. Due to the multi-stage arrangement a uniform energy dissipation is achieved in the vessel.
With the Rotor’s the fluid mechanical interference effect of the upper and lower vanes taking advantage of an optimization of the angle of attack outer shroud as well as the spacing ensures from the energy point of view the best deflections of flow in axial and radial
History of Company
The Turbulator concept was the brainchild of Ben Jansen Van Vuuren, entrepreneur and a respected businessman in the fertilizer industry. Being the owner of B.J. Fabrications and Van Vuuren Developments, he designed and manufactured blending plants for dry and wet mixing, used by most of the Agricultural Co-operatives in South Africa. He soon realized the opportunity to change the world of mixing.
This dream became a reality and he established Turbulator Mixing Systems in 1998. This unique mixing principle and concept was Patented in 1999 and two other patents followed shortly thereafter. The Turbulator Aerator and the Turbulator Wet Mill Combination was dually patented in 2003.
From the humble beginnings in a double garage in Parys, South Africa, Turbulator grew quickly into a manufacturing facility of 5500m² that currently exports to 18 countries.
Ben and his two sons, Soon and Gerhard, now run the entire operation from marketing to manufacturing, installation and commissioning of equipment and turnkey projects.
Turbulator’s forte in the market is the heavy to mix applications that comprise of many variables such as high specific gravity, high viscosity, high solid contents and temperature. The Turbulator’s unique “figure of 8” concept allows both radial and axial flow all in one mixing design.
The Turbulator reduces batch times by up to 80% without the assistance of other equipment like colloid mills or homogenizers. These above mentioned variables forces our competitors to add other expensive equipment to supplement their mixing ability and speed of production.
Turbulator™ has been engaged in the field of mixing technology for 14 years. Operational experiences are therefore available in a large number of industries solving problems as well as the trend to larger plants have led in the past to reinforce the efforts in the field of mixing technology.