World's first adjustable plug screw feeder

Initial situation

The Classen Group’s Fiberboard MDF plant in Baruth, south of Berlin, had been looking for a solution to dewater fibre with variable moisture content, and it also wanted to
solve a few issues, such as variable compression levels and frequent maintenance needs.

Flexible options

The main part of the solution at Baruth is the ANDRITZ Adjustable Plug Screw Feeder (“Adjustable PSF”), a patented world-first invention, which has a screw that can be moved backwards and forwards on its axis, by up to 10cm. This makes it possible to vary the size of the gap at the feeder exit, to raise or reduce compression, while production continues.

The new geometry and screw design maximise the volume of fibre between the threads, and the upgrade has increased the PSF’s capacity from 52 to 60 (bone dry) tonnes per hour. Although as Florian Grünberger, ANDRITZ’s Senior Sales Manager, points out, this project wasn’t focused on increasing volumes: 

Fast work 

With just half a year from order (December 2020) to installation (June 2021), and only three days available to install the equipment, timing was a huge challenge. The process, explains Dietmar Ulm, was “unusually fluid and fast. It’s a new construction, with so many new parts, a bigger, axially-adjustable screw in a new, hydraulically-adjustable housing, with a new wood-infeed chute, new drives and a new restriction ring. There were a lot of nerves – the plant needed to produce, because they had full order books. But we did it!” Andre Trebuth, Technical Director and Maintenance Manager at Fiberboard, confirms, “The mechanics and installers worked day and night and it all worked.”

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