Energy efficiency is a key aspect of reducing production costs and enhancing sustainability in plastic pipe extrusion. Modern extrusion technology and optimized processing can significantly reduce energy requirements, especially specific energy (Wh/kg).
Extrusion is an energy-intensive process involving heating and mechanical work (drive energy). For PVC processing, the material requires less heat input (approx. 3x less specific energy in Drive energy) than PO.
The design of extruders and screws plays a critical role in energy use. For double screw extruders used for PVC, relying less on heavy cooling and more on the energy from the motor (shear) to heat the dry blend effectively leads to lower specific energy consumption. A well-balanced screw design that avoids the need for excessive cooling contributes to a "maintenance free" concept and higher reliability, further reducing costs associated with unexpected stops. Air cooling for the cylinder and closed internal screw cooling are mentioned as solutions that can lower maintenance and potentially energy use compared to fluid-based systems.
Modern extruders require approx. 100 Wh/kg (excl. die) for a well-gelled PVC melt for pressure pipe, compared to a theoretical minimum of approx. 80 Wh/kg. The die itself adds 15-25 Wh/kg.
Lower specific energy consumption directly translates to energy cost savings. Furthermore, it can enable higher output for the same extruder size. By reducing the energy previously removed by heavy cooling, this energy can now be used to prepare more melt, potentially increasing torque capacity and further boosting output.
Technological advanced designs go without the need for high pressures and heavy cooling (energy loss). Sound equipment design for a wide processing window, combined with modern controls (e.g., Windows-based), aids in reproducible, energy-efficient production.