Pellet maker are known by several names, including pellet mill, wood pellets mill and wood pellet press among others. The basic principle of all pellet makers is the compression of the wood residue between a roller and die. The pressure and heat involved melts the wood residue together and forms it into a pellet shape. Once the pellets cool they hold the pellet shape and quality pellets are durable. However the above comment is to make the process appear much more simple than it actually is, as the characteristics and qualities of the raw material directly impact on how well the material performs in the pellet maker. The key factors which effect the materials performance are particle size, material density, moisture content and lignin percentage.

The general rule for particle size before going into the pellet is to be smaller than the diameter of the pellet to be produced. For example if the pellet mill is using a 6mm die, the raw material particle size should be 6mm or below. However several studies have shown that a smaller particle size of around 3mm performs better in the pellet maker producing a more compressed pellet. One of the reasons for this due to a smaller particle size, the pellet maker has better heat penetration into the raw material to melt the natural lignin to help form the wood pellets fuel. However, reducing the particle size below 3mm can have a negative effect on pellet compression. As a fine dust the rollers of the pellet find it hard to trap the material between the roller and die. Also as the fibre of the raw material has been broken down to such a level, compression results are severely effected. Once the correct particle size has been established the wood is processed in a hammer mill with a suitably sized screen to prepare the wood particles for the pellet maker. However material density also effects the performance of the pellet maker.

For example the pellet maker will have a different productivity with softwood residues compared to hardwood residues. The reason for this is it is easier to compress softwood and heat penetration is easier, therefore a higher productivity can be achieved with softwood residues. Some wood pellet manufactures create a blend of softwood and hardwood residues to improve the performance of the pellet maker.

Some raw materials may also require additional binder and lubricants as the percentage of natural lignin is not sufficient. If this is the case the most common additional binders are based around modified corn starch. The input is below 1%, and can improve pellet quality and also increase pellet mill productivity and can make out better wood pellets fuel.

Technical Guide on Wood & Biomass Pellets Production

At Technical Guide on Wood & Biomass Pellets Production we have many years of experience in pellet production, and we provide a pellet production consultation service. The Technical Guide on Wood & Biomass Pellets Production guide download will show you how to make wood and other fuel pellets. From more information, please visit our website: http://www.pelletmill.info