RZ Pellets – an Austrian pioneer

That is not all though, RZ Pellets GmbH has wood processing operations and runs ten heat plants in Austria some with power co-generation. The company has four pellet production sites all strategically located around Austria, facilities with a total combined annual capacity in the region of 250 000 to 280 000 tonnes.

Located around 120 km west of Vienna is the medieval town of Ybbs an der Donau. Here RZ Pellets built their first pellet plant in 2004 as part of an innovative three-way integrated bioenergy combine project with interconnected mass and energy flows. Adjacent to the site is one of central Europe’s largest sawmills belonging to forest industry giant Stora Enso. It processes around 1 million m³ of spruce sawlogs per annum producing sawn and planed goods along with speciality construction products.

Interdependencies

The sawmill complex supplies sawdust, planer shavings and woodchips to the pellet plant. Bark and woodchips are supplied to Biomasse Heizkraftwerk Ybbs GmbH, RZ Pellet’s 30 MWth combined heat and power (CHP) plant situated next to the pellet plant. These residues are conveyed directly as they arise from Stora Enso’s production to each recipient.  In return the CHP plant supplies heat to the sawmill including the dry-kilns, and heat to the Ybbs district heating network. The electricity is supplied to the grid.

The incoming wet sawdust from the sawmill is fed into a 2000 m³ silo for intermediate storage. From here it is metered into the 25 m long Swisscombi belt dryer. Exhaust heat from the flue-gas condenser is used to heat the dryer to 95-100 ^oC. The drying process takes about 30 minutes to bring the moisture content down from about 55 percent to 10 percent. The shavings from the planer mill have a moisture content of around 8 percent and are fed into a separate 2000 m³ silo. Sawdust from the dryer and shavings from the silo are then transported past a magnetic separator to one of two Reter hammermills. Corn starch and, if necessary, moisture is added at the hammermill.

– We add corn starch, less than 1 percent, to improve durability as 80 percent of our production is blown-delivered from a bulk truck. We get the best mixing here at the hammermill and since we always have the same spruce feedstock we don’t need to change dosing, explained Michael Pichler, from RZ Pellets.

The 6 mm pellets are produced by one of four Salmatec presses. The production goes to a conditioning silo before being transferred to bulk silo or the Arodo bagging line.

– This is really an online production. If Stora stop production for more than a few days then we would need to bring in external feedstock. So far we have never had to do so. The only stop is planned during Christmas, Pichler said.

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