Plastics

Development of a concept for the design of energy-optimised plasticising units

As part of the project, the project partners are optimising two single-screw extruders for use in plastics production and comparing these with the two original screw extruders in terms of performance and energy consumption. Depending on the type, design and plastic material used, the optimised screws achieve energy savings of 25-47%. 

 

Summary

In their original form, plastics consist of powder or granulate. When heated beyond their melting point, they form a viscous mass, which is pressed out of a shaping opening at a high pressure / temperature. A single-screw extruder is an example of a suitable processing machine, but such systems can be very energy-intensive depending on the design.

The aim of the project is therefore to optimise various single-screw extruders (three-section screw with rhomboidal mixing element, shearing and mixing element screw, optimised three-section screw, barrier screw) economically and in terms of energy. In each case a distinction is made between grooved barrel and smooth-bore tube extruders. The materials studied were a simple polyethylene (PE) and a linear polyethylene with low density (PE-LLD).

Results:

  • The greatest energy improvement is achieved with the optimised three-section screw. The reduction in energy requirements when processing both materials was around 47% and when using the smooth-bore tube extruder and grooved barrel extruder, it was around 35% (PE-LLD) and 25% (PE).
  • The optimised three-section screw can be used for numerous materials at both low and high speeds. However, at higher speeds better results are achieved in terms of output rate and specific drive power.
  • The three-section screw requires a lower specific drive power than the barrier screw.
  • Comparing the two new screws with the existing designs reveals that under identical operating conditions the former deliver a higher specific output rate than the latter.
  • The two new screws have a lower power consumption than the screws investigated previously.
  • On the two "original screws", there is no evidence of energy optimisation. However, from an energy perspective the shearing and mixing element screw performs worst of all the screws studied.

More Project Informations

Project title:  Entwicklung eines Konzepts zur Auslegung von energetisch optimierten Plastifiziereinheiten TV4

Project number:  01RC0046

Project period:  2001 - 2004

Project region:  Germany (North Rhine-Westphalia)

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Source: German National Library of Science and Technology Hannover (TIB)