Compact pelletizing

To supply group-owned paper mills with the required the energy, SCA utilizes existing potential. In the Swedish village of Tunadal, SCA is not only operating a sawmill but also a further processing line for wood for outdoor use and other planed goods. The same holds true for SCA Timber Supply's other factories in Sweden, England, and France. 

Where there is work there is potential

SCA Timber Supply employs 35 people in Tunadal producing about 110,000 m³/yr of planed goods. 25,000 m³ are glazed in an in-house facility and 95% of the wood is supplied by company-owned sawmills. The chip volume that accumulates during the processing of Nordic spruce equals an annual output of 11,000 t of pellets.

The management therefore decided to allocate pellets that supply the energy for the heat supply of the company-owned paper mill. The premises proved particularly challenging in terms of space. "A compact pelletizing structure was the only option", Markus Henningson, director of SCA Timber, pointed out during the interview with Timber-Online.

36 m² solution

In cooperation with UNY Konsult, the job for building the pelletizing system was awarded to German enterprise Salmatec, Salzhausen/DE. But not only the available space of 36 m² posed a challenge: "The comparatively long transport distance of 48 m from the chip bin to the production container is a distinctive detail of the new installation", Klaus Meister, service employee of Salmatec, explained. This was exactly the detail that was striking to Timber-Online during the on-site visit.

The new chip bin located behind the planing hall is fed with production residues. To achieve a homogenization of the basic material, SCA invested in an upstream shredder by Untha.

The screw conveyor with a length of 48 m transports the raw material to further processing. This is made possible by means of a spiral feed screw. 

The system's layout

The container layout appears very calculated and sophisticated. The actual pelletizing unit consists of Salmatec's ring-type die press, a heavy particle separator, a mill with filter, a paddle mixer, a high-power screw conveyor, the required gates, a reservoir, cooling screws with sieving, a cyclone, a spark gauging, a Grecon fire extinguishing system and a compressor.

To facilitate maintenance and servicing works, the production container is equipped with large gates.

Next to the low space requirements, Meister also listed the high system availability and the short installation time as advantages of this construction. The components used for this system are of the same high quality as those used in conventional pelletizing systems. Furthermore, the container solution was taken into operation in the factory prior to delivery.

The advantages of this approach become noticeable during installation. In Sundsvall, for instance, it took five days and the system was operational quickly.

Maxima 840

The center piece of the system is a Salmatec press of the type Maxima 840. The system performance is between 3.5 and 4 t/hour. The pressure required within the vertically functioning ring-type die comes from three edge runners. The press is equipped with a low-noise single-step V-belt drive that provides for an energy-efficient and smooth transmission. Center piece of the press is the generously sized spherical roller bearing of the rotor that ensures sufficient capacity even when the machine is operating under high loads. The swing-type press door stretches over the whole room which enables optimal access to all pressing tools.

The press is equipped with extensive standard and safety equipment, like for instance the overload flap, a shear bolts-free overload clutch as well as a temperature monitor.

Free storage, faster logistics

The pellets output is a screw conveyor system in a large storeroom. Since transport must be as efficient as possible, the four drop shafts are surrounded by a wall that facilitates loading with a shovel. First test runs show 6 mm thick pellets of a high quality.