In today’s economy, manufacturers are focusing on methods to decrease the cost of production. As raw material costs continue to increase, methods to reduce waste such as salvaging and reusing off-spec product — for example, waste due to startup, shutdown or operational upsets — becomes more critical.
The first step in reducing waste is to review operational procedures. With each passing day, more of our clients ask for Extru-Tech’s expertise to streamline their processes and maximize equipment efficiencies ultimately to improve their margins. During our review of their operational procedures, all too often we are told that startup and shutdown process steps are “fixed” or “it’s the way we have always done it” or similar comments. Most of the time, these standard methods of startup and shutdown that make the process easier create much more waste than necessary.
A primary example is the removal of non-essential extruder water injection. The use of water injected at the extruder inlet renders a fast-reacting process, meaning that when the injection level is adjusted, a change in the product is seen almost immediately. Conversely, if the water injection level is changed
Figure 3: Typical process diagram for a waste recovery system
WET WASTE
MATERIAL
INTAKE
3
2
4
6
1
5
SLURRY
7
8
COOLING WATER RETURN
CITY WATER
1 Conveyor Hopper
2 Conveying System
3 Metal Detector
4 Weigh Bin
5 Slurry Mix Tank
6 Dual Conditioning Cylinder
7 Cooker/Extruder
8 Makeup Water Tank
EXTRU-TECH, INC.
Through the use of a system such as the Extru-Tech waste recovery system, wet waste material is continuously conveyed, liquefied and injected as slurry directly into the extruder’s preconditioner.
EXTRU-TECH, INSeCpt.ember 2008 Extru-Technician 9
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