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Newsletter 4/2007

Dear Customers,

We would like to take the liberty of presenting you with our third newsletter of the year with which we want to inform you about new developments and products from Lipp Mischtechnik.

Optimization of extrusion processes with the dynamic shear force mixer REFLECTOR®

The REFLECTOR® allows fine powders to be mixed and homogenized with water, oils, lipids, lecithin or other viscous substances continuously in a matter of seconds.

If the REFLECTOR® is arranged ahead of an extruder, the extrusion process can be reduced to the pure shaping or – in the case of boiling extrusion – the pressure build-up.

Apart from the significant qualitative improvements

1. higher throughput can be achieved with available equipment and
2. and more constant / stable operating conditions can be achieved with available equipment;
3. new equipment can manage with less expensive extruder constructions.

This is how the REFLECTOR® works

Metered components pass through the REFLECTOR® in a matter of seconds.

The centrifugal acceleration imparted by the rotor blades causes turbulent particle circulation in the shear zone. Within the area of circulation, large and heavy particles tend to move to the outside where the shear force is greatest. In the shear zones, the rotor blades with their toothed ends intermesh with the toothed rings of the cylindrical stator.

Picture 1: Schematic illustration of an extrusion process with a REFLCTOR® arranged ahead of an extruder

Possible applications of the REFLECTOR® in combination with extrusion devices

The advantages mentioned above can be achieved also in the production of

• crisp bread
• flatbread, and the like
• snacks (potato chips, etc)
• cereals
• instant soups and drinks
• starch
• pet food, etc.

Illustrations 2 and 3 show the dynamic shear force mixer REFLECTOR® with axially parted, folding mixing cylinder. This REFLECTOR® is arranged ahead of a boiling extruder for the production of a special type of crisp bread.

Picture 2: A dosing screw conveyor continuously feeds flour into the supply nozzle at the front plate. The flour is being mixed with small amounts of water and fat that are being fed into the REFLECTOR® via additional nozzles. Via the outlet – bottom, to the side – the wetted flour is conveyed to the extruder inlet.

Picture 3: The REFLECTOR® consists of completely foldable hinged housing. After the machine comes to a full stop, one half of the housing can be comfortably swiveled up with one hand. The mixing chamber can therefore be cleaned dry quickly.

Further areas of application of the REFLECTOR®

The REFLECTOR® is similarly suited to the solution of many difficult mixing tasks where other mixing systems fail or require great effort to achieve satisfactory results. Here are some examples:

Fine mixing and deagglomeration: e.g. fine distribution of colour pigments in the carrier substance

Dispersing at all levels of consistency: solid-liquid mixtures of varying composition up to and including stiff pastes. This is possible even with coarse input materials and high-viscosity liquid constituents.

Kinetic fusing through specific application of high shear forces: continuous transition into a homogenous molten mass – also possible with coarse input material (e.g. lipids, waxes, chocolate, chewing gum, polymers, master batch).

System advantages of the REFLECTOR®

Compared to conventional dynamic inline-mixers the REFLECTOR® offers crucial advantages:

1. The reflecting faces of the active elements change the direction of the motion impulses within small areas, split up the product flow, break up agglomerates and fibrous concentrations, disperse and homogenize the bulk material.
2. The shear blades produce a strong axial feed impulse / momentum and additionally sweep the entire length of the mixing chamber so that only very little or no product will build up.
3. The mixing chamber geometry precludes the risk of blockages during proper / normal operation.
4. The strong pumping action of the mixer benefits the liquid cleaning of the mixing chamber through switching to circulatory operation; due to the very low hold-up only a few liters of the cleaning liquid are sufficient.
5. The throughput can be adjusted over a broad range without negatively affecting the mixing and dispersing effect by varying the rotational speed of the mixing shaft.
6. The mixing system works properly at all levels of consistency – from lo viscous to pasty and high viscous.

Design features of the REFLECTOR®

Due to the extremely short retention time the volume of this shear force mixer can - depending on throughput – be reduced to 5 to 25 liters. The retention time is governed by the metering and conveyor devices connected ahead. The cantilevered mixing shaft requires only one shaft seal. The drive of the standard model consists of a three-phase A.C. motor with V-belt drive.

Despite its high efficiency the REFLECTOR® distinguishes itself through its simple, operationally reliable, clear and accessible design; maintenance work is kept to a minimum. Machine sizes: several models for bulk material throughput from 200 to 400 kg/h. Overall lengths from ca. 1.000 to 2.000 mm. Tests in the trial facilities: In the trial facilities of Lipp Mischtechnik GmbH in Mannheim, a trial unit is available to be put to the test. Lease machine available upon consultation.

Picture 4: Dynamic shear force mixer REFLECTOR® with retractable screw conveyor for the production of vegetable and fruit juice (extraction preparation).

Should we have aroused your interest, we would be happy to answer all the remaining questions you might have.