Maine Woods Pellet Company Tour
Welcome to the Maine Woods Pellet Company. A lot of people ask us just how we make wood pellets so we've created this brief online tour. Place your mouse over a link to change the picture on the right.
First, we receive wood in the form of chips or sawdust from our suppliers. This wood is then sorted and stored. The wood supply is loaded onto the hoppers. Softwood on the left. Hardwood on the right.
From there it is fed onto what we call the green belt because it contains the green (undried) wood coming in.
This belt drops the wood into the primary hammermill which grinds it up to pieces of less than 1 inch in size. This ground wood drops into the infeed metering bin
which controls the rate of the wood fed onto the infeed belt which drops the wood into the dryer.
The dryer has several sections. The burner section has 3 zones which are all lined with 18 inches of refractory cement. Zone 1 operates around 1500°F. Zone 2 operates around 1300°F. The 3rd zone is the infeed zone where the wood is dropped in. The final and largest part of the dryer is the drum.
The drum has fins inside and constantly rotates to stir the wood around and dry it out.
When the wood becomes dry enough it will come out of the dryer outlet and travel through a cyclone where the air flow continues on and the dried wood drops into the dry material hammermill.
This hammermill grinds the dried wood up even further, into a sawdust-like material. At this point the wood is at about 8% moisture. From the dry hammermill, the wood is pulled by the milled material fan
into another cyclone and airlock. The wood then drops into the distribution screw which fills 4 bins. The fuel feed bin and three pellet machine feed bins.
The pellet machine feed bins meter out the supply of wood that is fed into the conditioner which in turn delivers the wood into the pellet machine. The wood is then compressed and forced through small tapered holes creating wood pellets.
These pellets drop into a transfer screen which shakes the pellets, delivering the pellets into a bucket elevator and the dust into the dust recovery system. The bucket elevator dumps the pellets into the cooling bin where they are cooled and then delivered to one of the two 500-ton storage silos.
When the pellets are removed from the storage silos, they first go through the shaker screen. This is the 2nd screening to remove dust. The dust collected from the transfer screen and shaker screen is sucked up by the dust recovery fan, processed through the baghouse, and then stored in the front section of the fuel bin.
The dried wood in the main section of the fuel bin is at 8% moisture but the dust in the front has been squeezed through the pellet machines and is at only 5% moisture. The wood and dust in this bin are where the dryer gets its fuel. The wood and dust from this bin drops into the fuel hammermill - to ensure that all of it is a fine dust - and is then blown into the burner.
When the pellets pass through the shaker screen, they are either diverted to the North Silo for bulk shipment or to the bagging machine where they are metered out into 40 pound bags, stacked into 1-ton pallets, and wrapped for retail sale.
Does all of this sound difficult to operate? Fortunately, this is a state-of-the-art pellet mill. Everything here is controlled by a complex computer system of programmable logic controllers - or PLCs. This is one of the 5 PLC storage cabinets and this is what it looks like inside. This one is part of the dryer PLC and it is housed inside the dryer power distribution room - one of 3 power rooms on site.
Even our pellet boiler that heats the building and our pellet machine greasers are computer controlled.
The operators control the plant from the touch screens in the control room or from the portable console out near the pellet machines.
We hope you have enjoyed this brief online tour. If you have any more questions, please see our Contacts page for how to reach us.