Analysis of energy flows in the manufacture of synthetic filaments

An analysis of energy flows showed significant potential for optimisation. Relatively simple measures can reduce energy requirements by around 25%. 



Hahl Filaments GmbH of Munderkingen manufactures filaments for the brush and technical textile industries and for leisure sports.

The company uses 12 million kWh of electricity, 5 million kWh of natural gas and 4,300t of raw materials, mainly PET and PA, each year.


Project objectives

  • To reduce energy costs and lower the waste heat load in the production process
  • To reduce the CO2 impact from the energy required and to improve workplace conditions
  • To improve competitiveness by lowering specific energy costs per tonne of product and reducing environmental pollution

The whole company was assessed, particularly as regards its energy and cooling water needs. To this end two representative production lines were selected and their consumption measured and recorded in detail. For comparison purposes, the energy theoretically needed to manufacture the filaments was estimated and the optimisation potential derived from this. 



Proposed solutions:

An analysis of the energy and material flows showed that the extruder and tunnel kilns used to heat the filaments consume the most energy (extruder 36%, tunnel kiln 37%). The energy required for cooling is also significant, accounting for 9% of electricity consumption.

Simple measures such as insulation can lower the amount of energy required by the extruder. Research has also shown that the latest extruder technology with internal insulation and improved screw geometry can significantly reduce the energy requirements of these units. Better insulation and a smaller sealing gap in the tunnel kilns can also reduce energy requirements considerably. The system is currently cooled with a cooling tower and several chillers. Alternative cooling methods based on spring and river water were developed.


Environmental benefits:

The relatively simple measures described above can reduce energy requirements (electricity and natural gas) by around 25%. This results in the production of 2,500t less carbon emissions each year.


Cost benefits:

Together, the optimisation measures – reduction in energy and steam requirements, implementation of alternative cooling systems – can save around €350,000 per annum.

More Project Informations

Project period: 2005 - 2007

Project region: Germany (Baden-Württemberg)

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Source: Landesanstalt für Umwelt Baden-Württemberg