World Grain - December 2007 - 38

FEATURE: INCREASE AQUAFEED PRODUCTION THROUGH PLANT OPTIMIZATION

Figure 3: Peripheral die openings

extension in a pattern that is radial to the
extruder centerline (see Figure 3, above).
DOWNTIME AND USABLE PRODUCT
Reduced downtime is often overlooked as a bottleneck to higher plant
capacities. An extrusion line that has a
throughput of 10 tph potentially loses
five tonnes of product for every 30 minutes of downtime. A certain amount of
downtime is unavoidable due to scheduled maintenance, product changeover
and other plant functions such as fumigation and sanitation.
Many feed manufacturers believe they
operate their lines 24 hours a day, seven
days a week and are surprised to look at
end-of-the-year production records that
can indicate up to 20% actual downtime.
Practices that can be implemented to reduce downtime are as follows:
* adjusting production schedules for
minimum product switch-over time;
* installing hardware tools that have
quick-change features;

* designing control systems for compressed startup/shutdown modes;
* training production personnel to
reduce downtime;
* implementing preventive maintenance programs;
* designing system hardware for
maintenance and cleaning accessibility.
In addition to downtime reduction, increasing usable product is a significant
opportunity where off-spec product may
run as high as 8% of total production.
Considerations for increased levels of
usable products include the following:
* automated retention time control in
preconditioners to reduce startup/shutdown wastes;
* screw element and liner designs to
give positive conveyance;
* high extruder speeds and variable
speed drives to shorten process response
times;
* online, automated control of SME
and recipe analysis;
* automated extruder control systems
that compress startup/shutdown modes;
* experienced and trained production
personnel to control process;
* process flows that handle the product gently;
* systems to recycle under-processed
material and off-spec product.
UPSTREAM/DOWNSTREAM
PROCESSING
It is easy to focus on the extrusion
operation and the potential bottlenecks.

However, most bottlenecks occur along
the process flow in areas other than the
extruder.
An audit to increase plant production
levels should include an evaluation of
each unit operation along the entire flow.
Potential bottlenecks could be found in
one or more of the following areas:
* grinding/sifting;
* storage;
* conveying;
* drying/cooling;
* coating;
* packaging.
All unit operations along the process
line must be properly sized to avoid a
flow bottleneck. As each bottleneck is
identified and eliminated, a new, secondary bottleneck will likely appear. A different bottleneck may be identified for
each product that is manufactured in a
given process line.
This auditing process can continue indefinitely, but at each step it is necessary
to do a cost/benefit analysis to determine
WG
if the economics are favorable.
This article is based on a presentation by
Galen Rokey, Wenger International, Inc., at
the Aquafeed.com conference, Aquafeed
Horizons 2007, which took place during Victam
International, Utrecht, Netherlands in May 2007.
Rokey may be contacted at GalenR@Wenger.
com. For more information about Aquafeed.com
Conferences, visit www.aquafeed.info.
We want to hear from you - Send comments and
inquiries to worldgrain@sosland.com. For reprints of
WG articles, e-mail reprints@sosland.com.

Extruder OEE
Flexible shaping
of different products

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AMANDUS KAHL GmbH & Co. KG, Dieselstrasse 5-9, D-21465 Reinbek / Hamburg, Phone: +49 40 727 71 0, Fax: +49 40 727 71 100
info@amandus-kahl-group.de, www.akahl.de

For more information, see Page 54.

December 2007 / World Grain / www.World-Grain.com

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World Grain - December 2007

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