Metri2 and Kaks2 – Biomass silo discharger with mechanical scrapers

The biomass silo discharger plays an important role in a biomass heating plant. If the silo discharger is unable to process the solid fuel that is inside, the boiler will rapidly run out of fuel.

From the beginning, Säätötuli has ruled out the use of spring-arm silo dischargers as they have some major flaws:

• They are not able to process fuels with some bigger wood-chunks, as you will get when chipping the wood with a chipper with unsharpened knives.
• Springs are usually made with sheet-metal, meaning that they can easily bend out of form for example if a stone gets into the silo.
• The mechanical parts are in the middle of the silo. In case of a mechanical breakdown, the silo must be emptied by hand in order to repair the silo discharger.
• The spring-arm silo discharger often empties only a disc-shaped area in the middle of the silo, leaving fuel on the sides.

The Metri2 and Kaks2 silo dischargers have been designed originally for farmers. Most of the farms in Northern Europe make their own woodchip fuel with a chipper running on the PTO of their tractor. With the hectic life of a farmer, sharpening the knives of the chipper is usually not considered a priority. This ends often in lowly calibrated woodchips that can be challenging for a silo discharger.

To be able to process the difficult fuel that is available on farms, Säätötuli came out with the design of the Metri2 and Kaks2 biomass silo dischargers. Instead of having a sheet-metal spring-arm, the Metri2 and Kaks2 have sturdy metallic rakes that will move the fuel from the sides to the auger in the middle of the silo.

The Metri2/Kaks2 biomass silo discharger was the first product to feature Säätötuli’s special silo discharge auger design. A silo discharge auger can’t be like the auger that is used between the silo and the boiler as it would move too much fuel at a time, resulting on forces strong enough to wear the bearing of the auger in no time. Säätötuli designed its special silo discharge auger to avoid that problem and ended up with the current design of metal-plated auger. This design has another advantage: if ever there are some sticks from branches that end up in the silo, there is a good chance that the stick will get between the metal plates and be broken in pieces when the auger moves.

The Metri2/Kaks2 biomass silo discharger also features a counter blade where the discharge auger enters the tube. This counter blade will cut any wood chunk that is too big to enter the tube.
The Metri2/Kaks2 silo discharger is equipped with a strong 0.75kW (1HP) electric motor with a gear multiplier. This design ensures that enough power is available for the silo auger to break branches and the counter-blade to cut the oversized wood-chunks. The motor is connected by chains to the flywheel that will run the auger, but also move the scrapers inside the silo. Scraper movement can be modified simply by moving the arm on the flywheel on the desired position.

Maintenance is also easy as all the moving parts are located under the Metri2/Kaks2 silo discharger.

The Metri2/Kaks2 silo discharger can be sold as only the base unit for a biomass silo, or with metallic silo walls and roof. It can be installed below or above ground as long as there is an access under the discharger for maintenance.

Technical specifications of the Metri2/Kaks2 silo discharger

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