Wood Pellet Equipment and Pellet Fuels

Producing wood pellets requires a series of processes and a variety of equipment. You can produce a wood pellet on both a small and large scale, however the equipment may change. Various wood resources can be processed into a wood pellet, how the process and equipment may change. The first core step of pellet production is raw material size reduction. The equipment used for size reduction depends on your chosen raw material. For large pieces of wood, for example logs, a chipper or crusher will first be used to produce the wood into small chips. However for the pellet production process, the wood has to be reduced further in size. The chips will then be used in a hammer mill. A hammer mill has a set of hammers spinning around 4,000 rpm, and as they impact with the wood chips, the chips shatter into smaller pieces. Once the chips have been reduce to a small enough particle size a fan remove the wood particles from the base of the hammer mill. and then a cyclone separator is used often with a rotary value to separate the particle from the air stream. Before pellet compression can take place, enough moisture must be removed so compression is possible. Therefore for most wood used in pellet production the wood particles must pass through a dryer before it can enter the pellet mill.

Wood Pellet Mill and Other Pellet Mills

Once the sawdust has been dried down to between 10-15%, it is ready for the pellet mill. The two main designs of pellet mill are the flat die and ring die. The flat die is the first design of pellet mill, invented at the beginning of the 20th century for feed pellet production. The ring die design was invented later, with the improvements being more suitable for large scale pellet production, lower energy consumption and reduce wear on consumables. However this flat die design is much cheaper to produce and are so are the consumables such as the rollers and die. Therefore today because of these features, flat die designs are popular for small scale production, and ring dies are more popular with large scale production. There are several other designs such as hydraulic presses and double die designs. However these are yet to reach mass market appeal, as their benefits are not yet proved in many aspects of pellet production.

To improve wood pellet quality and reduce the load on the pellet mill, steam conditioning is a common piece of wood pellet equipment. However steam conditioning is expensive and dangerous, so generally only used on large scale pellet plants. There are a number of pellet binders and lubricants, for example made from corn starch that can replicate the effects of steam conditioning in the pellet mill. Once the sawdust enters the pellet mill and is compressed through the die by the rollers, a combination of heat and pressure forms the pellet. When the pellets exit the pellet mill they are at around a hundred degrees. The pellets must be cooled before packaging and storage to maintaince their shape and integrating. Before storage the pellets should also be passed over a sieve to remove excessive fines and dust. Excessive dust in the pellets can create issues for some pellet stoves and pellet boilers. Pellets are often packaged and stored in plastic bags, however this is not encourage due to the waste, reusable bags make much more sense.

PelHeat Wood Pellet Production Guide

At PelHeat we have many years of experience in pellet production, and we provide a pellet production consultation service. The PelHeat guide download will show you how to make wood and other fuel pellets.

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