While the wood pellet industry has seen remarkable expansion, pellet from agricultural residues is growing too, albeit at a different scale. Nonetheless the interest for farm-scale turnkey straw pellet lines is gaining momentum as Lithuanian agricultural machinery and pellet equipment manufacturer JSC Radviliskis Machine Factory reveals.
A medium-sized town, population c. 55 000, Radviliškis is situated in the heart of prime agricultural land in north-central Lithuania. Although known for its peat extraction, wood processing and furniture industries, agriculture emerged post-WWII during the Soviet era as a primary industry. So it is no coincidence that today numerous agricultural equipment dealers, domestic and international, have located premises, workshops and showrooms in the region.
One such major domestic equipment manufacturer established in 1949 bears the name of the town, JSC Radviliskis Machine Factory or simply “Factory.LT” on account of its 12 ha site. In 1976 it started to produce grass flour pellet presses and feeds briquette machines. In 1992 it began production of wood pelleting equipment followed by straw milling and pellet production equipment in 2005. Today it is the only manufacturer of such equipment in the Baltic States.
– Since we sold our first straw-pelleting unit, to Germany in 2007, we’ve noticed an increasing interest, both here in Lithuania, and elsewhere, especially over the last three years, said Jonas Bliudzius, Director of Commerce for Radviliskis Machine Factory during a visit.
He added that recent deliveries are to clients in countries with high grain or oilseed production such as Russia, Canada, Romania, Bulgaria, Ukraine and Kazakhstan. And during the visit, a straw pelleting plant rolled out of the facility loaded onto two trucks, destination Belarus.
Gytis Giedraitis, Director of ZUB Eriskiai, a large arable farming company is perhaps a typical representative of this growing interest. His company farms some 2 700 ha of which 2 220 ha is cereals and rapeseed and the rest is sugar beet.
In 2011 he invested in a 1.5 tonne per hour straw pellet line as a means to add value to 2-3 tonnes of straw per ha per annum. Annual pellet production is around 4 000 tonnes, the capacity sweet spot for full utilisation of straw produced on the farm.
– Straw pellet gets us into local and regional energy markets with an existing resource we’ve already produced, commented Giedraitis, adding that all the production is sold to a pellet dealer.
The set-up is very straightforward, automatic, and requires only two personnel per shift. Straw bales are loaded onto the feed conveyor and manually de-stringed. The shredder breaks the bales and shreds the straw into 10-90 mm pieces.
The shredded material is passed through a stone trap and screw-conveyed to a hammer mill that grinds the material down to a 1-3 mm fraction and blows it into the cyclone battery, separating the particles from dust, the latter of which is captured in an air filtration system. The particles from the cyclones are screw-conveyed to an intermediary storage bunker from which the material is fed through a batcher and mixer to the rotating die type pellet press itself.
On the outer side of the die, a knife cuts the pellets to the required length. On exiting the pelletiser the pellets are cooled from 90-100 °C down to 25 °C in a vertical cooler. After cooling the pellets are screened, removing residual fines that are generally reused in the process. The dust-free pellets are ready for storage, fed into the packaging equipment and packed into big bags (600-1200 kg) as well as 15 kg bags.