Wood Pellet Plant

Wood pellet plants are a complete set up to equipment used to produce wood pellets, generally for use as pellet fuel. There are several pieces of equipment used to produce pellets, including wood pellet mills.

Hammer Mills and Particle Size Reduction

One of the first pieces of equipment in the wood pellet plant is the hammer mill or chipper. Before pellet compression can take place the raw material must be reduced to small uniform size. The particle size required does vary on the diameter of pellet to be produced and the mm diameter hole in the pellet mill due. For example, pellet fuel is usually produced to 6mm pellets, as this diameter of pellet can be used by all pellet stoves. Therefore the particle size produced via the hammer mill, chipper or crusher must be smaller than 6mm. Some pellet boilers can use larger diameter pellets, therefore in these circumstances a large pellet could be produced such as 8mm, therefore the hammer mill must produce particles less than 8mm. These are the minimum requirements for particle size reduction, however there is evidence to support that a smaller particle size of around 3-4mm produces a better quality pellet. The reasons for this is a smaller particle size allows for better heat penetration, to produce a stronger more durable wood pellet fuel.

Wood Moisture Content and Dryers

Before the raw material is ready for the wood pellet mill, a dryer is usually included in the wood pellet plant. Most virgin wood resources have a moisture content of around 50%, and for pellet production that figure needs to be closer to 15%. Therefore after the hammer mill, a flash dryer or rotary dryer is included into the pellet plant. A flash dryer is also known as a air current dryer or pipe dryer. The wet particles are carried in a hot gas stream through a pipe network and buffer cylinders. A cyclone separator is then used to separate the dry particles and wet air. A flash dryer is usually used for raw material which require only around 10-20 moisture removed. For large wood pellet plants rotary dryers are used as they can be controlled.

Wood Pellet Mills and Biomass Pellets

The pellet mill or wood pellet mill is the central piece of equipment in the wood pellet plant. As stated, before pellet compression in the wood pellet mill can take place, the raw material must have the correct particle size and the correct moisture content. It must also be free from contaminates such as stone or metal, which could damage the pellet mill rollers and die. Any key feature the raw material should have for consistent and efficient quality pellet production, is material constituency its self.

Wood Pellet Stoves and Pellet Burning

Most wood pellet plants are used to produce wood pellet fuel for pellet stoves and boilers. As stated this usually means producing a pellet of 6mm or perhaps 8mm for pellet boilers. Wood pellet plant owners actually prefer producing large diameter pellets, as the cost to produce the pellets is less. A large diameter pellet consumes less power during particle size reduction and pellet compression in the pellet mill.

The Wood Pellet Production Guide © PelHeat Ltd - Wood Pellet Plant