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AQUAFEED PROCESSING
twin screw extruder is 1.5 to 2 times the
cost of a state-of-the-art single screw extruder
with comparable hourly production
capacity.
Because of the increased costs, only those
feed products with strong value added potential
are processed via the twin screw extruder.
Specific product characteristics or processing
requirements where twin screw extrusion
systems have found applications are as
follows:
1. Ultra-high fat feeds (above 17 percent
internal fat)
2. Products which have high levels of fresh
meat or other high moisture slurries (above
35 percent).
3. Uniform shape/size product (portioned
foods)
4. Ultra-small products (0.6 to 2.0 mm diameter
products)
5. Co-extruded products (complex pet food
treats)
In those cases where twin screw extrusion
for aquatic feeds is justified however, the
previously mentioned processing requirements
have led extruder manufacturers to
design twin screw extruders (Figure 1) and
ancillary components capable of covering an
extreme range of processing applications.
One example of this new breed of parallelshaft,
twin screw extruders is the Magnum
ST series, developed by Wenger Manufacturing,
Inc.
With maximum speeds up to 1,200 rpm
and power levels up to 165 kWh/t SME at
volumetric capacity (Table 1), the Magnum
ST Series provides optimum extrusion versatility.
These economical, high capacity extruders
allow processors to utilize a smaller extruder
model without sacrificing capacity.
Alternatively, the higher SME capabilities
can be utilized to meet unique product requirements.
C 2 TX EXTRUDER
Table 1: Technical Data for Wenger Magnum ST Twin Screw Extruders
Screw
Diameter
(mm)
Maximum Volumetric
Capacity
(kg/h)
Installed Power at
Maximum Speed
(kW)
• FEED TECHNOLOGY UPDATE — November 2006 •
• FEED TECHNOLOGY UPDATE — June/July 2007 •
Maximum
Screw Speed
(rpm)
57 1,700 185 1,200
85 4,800 450 1,200
115 12,000 1125 1,200
144 22,700 2250 1,200
Figure 2: Conical Co-rotating Twin
Screw Extruder
The C 2 TX (conical corotating
twin screw extruder)
is the most recent
extrusion system
introduced to the feed
industry (Figure 2).
The C 2 TX’s conical design
allows for positive
compression in the barrel
and reduces possibility
of back feeding.
Positive compression