Fines Concentration mainly occurs in silos with 45 degree or lower slopes due to funnel flow. Silos with bottom slopes of 60 degrees degrees tend to accumulate far fewer fines because pellets go down in a Mass Flow. See the graphic.
The cures for fines build-up? One is to Vacuum fines out of your low slope silo when it becomes “empty”. Do this once a year or so which will prevent heavier concentrations that occur after years of fillings. Vacuuming out a bag silo every year or two is also a good practice, even with a MESys type “Spring-Bag” (see photo). If you have a Froling funnel bag, a vibrator can be added to these that runs when the feed blower turns on, getting fines to exit with the pellets before they become concentrated.
Planning a pellet boiler installation for your home or building? Choose an interior silo like the MESys FleXILO “spring-bag” that looks like a cube when full but the springs pull up the floor into a steep V when it nears empty. Or get a Froling silo with a vibrator. If you are planning on an exterior silo, the 60 degree bottom cone is recommended with pneumatically filled boilers.
Next week we will continue this topic. If you have experience with fines build-up, please comment and send photos if you have them.