Delta Hybrid units have passed an urgent problem with brilliance in the mill Saalemühle of Alsleben, Saxony-Anhalt: Flour had to be conveyed into a silo with a height of 65 meters. But this was not possible with conventional blowers.

With its three milling installations Saalemühle counts among the most efficient in Europe. The compressed air required for pneumatic conveying of the milling products had been produced at first with approx. twenty nonsilencing air-cooled Aerzen positive displacement blowers, producing maximum pressures of 0.4 bar, partly even 0.95 bar according to needs.

Delivery height increased

Operation ran smoothly - as long as the products had to be conveyed into a silo with a height of only 45 meters. Some problems only arose when since 2007 the products of mill 1 had to be conveyed into a new flour silo with a considerable altitude of 65 meters - after all 20 meters higher. The present Aerzen blower GM35S had no problems with the old delivery height, but this increase could not be handled anymore by the previous differential pressure of 0.95 bar.

„Nevertheless we have tried to feed the new conveying altitude by former Aerzen blower by exceeding the maximum pressure and therefore, we have consciously ‘overstretched’ the blower. But things could not go on like that,” emphasizes Holger Mattner. He still takes care of the technical units of his former employer as “production
manager Mühlentechnik (milling technology)” and external service provider. Resolution by Delta Hybrid Together with Aerzener Maschinenfabrik a solution should be found. At the beginning of 2009 an additional compressor of the new Delta Hybrid Aerzen rotary lobe compressor-series was installed. “This new unit works with a constant maximum pressure of 1.2 bar and therefore, still well below the maximum pressure possible of 1.5 bar. Since its commissioning the unit works every day around the clock without any problems. We are now able to convey 25 tons of flour per hour from the point of submission to a height of 65 meters. This is thanks to the very effective acoustic hood at a particularly low noise level,” milling expert Mattner is pleased.

Following commissioning of this new Delta Hybrid unit and a short testing phase, Aerzen blower GM35S being responsible for this production section was taken off the grid. From now on it will only be available for emergencies.

Due to the good experiences with the first Delta Hybrid unit, the Saalemühle/Alsleben has procured even a second silenced Delta Hybrid unit, only a bit smaller in conveying capacity. In future, this unit takes over the tasks of Aerzen blower type GM25S. Flour has to be conveyed by the produced conveying air from the second mill unit with an hourly output of approx. 13 t over an altitude difference of 65 meters into the new silo.

At present, there are no problems with the pneumatic conveyance of grinding material of the third mill unit, as the material is conveyed into a silo with an altitude of “only” 45 meters.

Holger Mattner, manager milling technology »With Delta Hybrid we solved the conveying problem optimally without limitation.«