PETpla.net Insider 01+02 / 2013

BOTTLE MAKING 25 PET planet insider Vol. 14 No. 01+02/13 www.petpla.net Topics Series Part 1/2: Energy savings potential with stretch blow mould- ing machines Air Recycling System Plus yields a 30% saving in high pres- sure air * Savings in low and high pressure compressed air *by Gerrit-Mathias Spalteholz, Sales Manager at Technoplan Engineering SA The relentless rise in energy costs over the years means that it is essential for every com- pany to seek out opportunities to reduce its energy consumption wherever possible. One example of a major consumer of energy is the stretch blow moulding machine and the compressors associated with it. It is therefore important to reduce the energy consumption of these machines. This objective can be achieved using the patented dual compressed air recovery system ARS+ (Air Recycling System Plus) by Technoplan Engineering SA which, apart from major cost savings, also generates a sustained improvement in the company’s eco-balance. For 15 years the Air Recycling System (ARS) has been recovering 13% of the high pressure air and 37% of the low pressure air consumed by stretch blow moulding machines. This figure of 37% represents the entire complement of the low pressure air consumed in PET bottle manufacturing, so that no low pressure air needs to be supplied from outside the machine. However, the trend is moving towards even greater savings in expensive high pressure air. The fol- lowing article gives information on the status of the most recent develop- ments. Manufacturing a PET bottle calls for dry compressed air that pre-blows the preform at a pressure of between 8 and 12bar and gives the bottle its final shape at a pressure of between 25 and 40bar. On completion of the blow cycle the discharge valve opens and the compressed air leaves the machine via the silencer.Then the finished bottle exits the form ready for the next bottle blank. Depicting the process in this simple and straightforward manner makes it easy to see what enormous savings in terms of energy and costs can be achieved through compressed air recovery. The ARS+ double recov- ery facility for compressed air works on the following principle: Once the blow moulding cycle has been completed and the bottle has reached its final shape, the discharge valve (original from the stretch blow moulding machine) opens and the compressed air exits the finished bottle. After this it flows through the first ARS+ valve into the high pressure air tank (also a newly installed feature). Once a precisely determined period has elapsed, the first valve closes. The second valve opens and the second tranche) air flows into the low pressure air tank. The second valve closes and the third valve opens to allow the remaining air to escape through the silencer. ARS+ recovery valves by Technoplan Engineering SA in operation