If your silo has a 45 degree (or lower) sloping silo floor fines can build up. If fines get into the burner, faults can occur. We recommend that you install a fines cyclone in the pneumatic feed line.
This wood pellet boiler is set up with a cyclone that filters out fines from their silo. Like many other pellet boilers, the Froling P4 fills itself twice a day from its remote silo using a pneumatic blower system. Pellets from the silo ride on a loop of air from the silo to the boiler but fines tend to continue back to the silo–and that is where the cyclone is installed.
A nice shot of a fines cyclone. Fines laden air is blown into the side pipe (shown to the left), it is spun around the cyclone dropping the fines into the bucket and then flows back to the silo.
Pellet fines are more like flour than sawdust from a saw. That is why they tend to pack inside a silo that has low slopes.
A view of fines collected inside a cyclone’s bucket.
If you are planning a new installation, specify an exterior silo with 60 degree bottom cone or build an interior silo with 60 degree walls and a central auger. Yes, this reduces the interior volume of the silo but if the pellets are stuck in place on a 45 degree slope, they are of no use to you unless you manually rake them down.
Thanks to Scott Nichols of Tarm Biomass for the cyclone photos!