At the BASF factory in Rudolstadt the granulates are transported in a piping system with a length of 450 m from one production range to another. And also pneumatically from silos to the packing plants. “For these transport tasks we need differential pressures. For transport through the pipings the highest pressure required is 3.3 bar, for transport from the silos to packing plants however only 0.95 bar. Therefore, we work in both ranges with customized production concepts”, says foreman Stefan Ortschig.The 3.3 bar pressure is produced by two oil-free Aerzen Screw Compressors VM 10 with a conveying capacity of 9.2 m³/min. A third compressor is provided as stand-by unit.Between all three compressors a continuous change is effected. However, for the 0.95 bar facility the pressure is produced with an Aerzen Positive Displacement Blower. Therefore, a GM 35S was used with a constant air flow of 30 m³/min. and two smaller units GMa 11.2 with a constant flow of 6.2 m³/min. each.This production concept exists still today in principle – however with a serious difference: In 2007 an additional Aerzen Positive Displacement Compressor of the new series Delta Hybrid (type D 62 S) was installed and immediately taken into operation as the main supplier of conveying air. “Because of the higher capacity of 36 m³/min. it was possible to supply all three conveyor lines with compressed air at the same time”, recalls Production Engineer Jörgfried Heise.Since commissioning in 2007 the new Delta Hybrid-Unit has been running in continuous operation and provides almost the complete needs in 0.9 bar range. Only in exceptional cases is it supported by a small unit of the old system. The largest blowers are now only used as stand-by unit and during maintenance work.In order to prevent a contamination of the hygroscopic products with humidity, the air flows through an adsorption drier at the start of the process before reaching the blowers at the outlet the air is cooled to approx. 25 °C through the use of two reservoirs and only is it used for the conveying system.“As the new Hybrid Units have been more energy-efficient we have been convinced that this is the way forward and since the commissioning it has run continuously and the maintenance work has been limited to the control of the oil level”, says foreman Stefan Ortschig.
