They call it "The Beast"

Bioenergi Lulea (Sweden) hast just been successfully starting operation of a pellet mill of Graf Equipment GmbH.


The pioneer of wood pelleting started 20 years ago with 4 pellet mills. Being meanwhile part of the SCA group, Bioenergi Lulea continues pioneering and even goes further towards innovation and technological progress.


Graf Equipment’s wood pellet mill GEPM 900/138 meets the latest technological standards and hence is the state-of-the-art wood pellet mill on the market. Developing this mill, particular emphasis was laid on sturdy and reliable design and state-of-the-art measurement as well as control technology was used.


Improvements and reinforcements were made on all critical parts. The main shaft has a larger diameter than before which enables to use larger bearings carrying more load. The risk of breakage of the main shaft has been minimized by its design and by adjusting the diameter. The die holder and main pulley were positioned so that the centre of gravity is within the middle of the machine. Thus the power train has a lower bending moment and relieves bearing and shaft. An anti-vibration body absorbs vibrations, compensates impacts arising from product sways and avoids hair-cracking in the frame.


To ensure a better product quality, a stable operation and a higher torque, the circumferential speed of the die has considerably been reduced. The slip control of the rolls allows a view to the ongoing process. The product distribution can be controlled, arising overcharge be recognised in time and status of die and roll be evaluated. This control tool assures operating the mill until its load limit. Intelligent software is prepared for the different scenarios. Hence, production capacities and machine availability are augmented and costs reduced.


Also the use of a conical mould promises a simple and fast maintenance. It has to be biennially replaced and when changing the absolutely round dies there is no need for calibration. If formerly a die change took up to 8 hours, it now can be executed within 2 hours.


Due to innovative approaches of GEPM 900/138, its sturdy and reliable design and the synergy of software and sensors, the GEPM is insensitive to external influences, product sways and requires low maintenance costs.


Bioenergi Lulea and GRAF GmbH have been maintaining intensive contact within the field of spare and wear parts for many years. Hence the experiences and requirements of both parties have been implemented in the machine. Since the GEPM with its weight of approx. 15 tons and its rugged steel construction seems so huge next to the old machines, she affectionately was baptised “THE BEAST”.

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