Increasing energy efficiency of pipe extrusion processes through advanced polymer design

Most process improvement efforts in the pipe extrusion industry were traditionally aimed at increasing the throughput and/or enhancing the product quality. In recent years an additional aspect has been steadily gaining relevance : Energy efficiency. This has been driven by rising energy costs as well as by increased environmental awareness. In an era of tight public budgets for investments in infrastructure and intense inter-company competition any gains in production efficiency can be a decisive competitive factor. At the same time public and regulatory attention is turned more and more to aspects related to the eco-profile of plastic products, such as water and carbon footprint, impact on depletion of non-renewable resources etc. So any improvement in energy efficiency of the pipe production process will have a twofold benefit, impacting both the bottom line as well as the eco-balance of the products. From the perspective of the raw material producer, this paper investigates the various possibilities to influence the energy consumption during pipe extrusion. The impact of extrusion parameters and polymer characteristics as key influencing variables will be discussed, as well as limiting factors. Then the performance of various High Density Polyethylene (HDPE) products will be examined in this respect. Results of laboratory investigations as well as practical field tests will be presented to illustrate the achievable improvements as a function of the particular processing situation. Finally an effort will be made to put the efficiency gains in a wider context to show the respective benefits of advanced HDPE materials. Keywords : Pipe extrusion process; energy efficiency, High Density Polyethylene, polymer design.