Pellet Making

Pellet making is a subject that is interesting more and more people, particularly in the area of producing fuel pellets, for example wood pellets. So what is involved in pellet making, and what materials can be processed into pellets.

Wood Pellets

Making wood pellets today is what most people are interested in. Due to the general rising price of oil and gas, and concerns over global warming, wood pellets have seen a rapid growth. With the increase in the purchase of pellet stoves and boilers, more people are interested in how this fuel is made, and is it possible to make the pellets on a small scale. The next few years will see a dramatic rise in large scale pellet production plants, however there is also an opportunity to produce wood pellets on a small scale. To produce wood pellets, the wood must have a low moisture content, or drying equipment will be required. The wood must also be reduced to a small uniform sized dust before it can be compressed into a pellet. Once a dry uniform dust is obtained, the material can then be processed into pellets. Through sufficient heat and pressure the wood is shaped into pellets.

Biomass Pellets

Other raw materials besides wood can also be used in pellet making, see left for examples. This includes purpose grown energy crops such as miscanthus, switchgrass and hemp. It also includes agricultural waste materials left over from food production, for example wheat straw, barely straw and corn stalks. All of these raw biomass materials can be processed for making pellets. Making pellets from these biomass materials is often easier and has a lower power consumption than producing wood pellets. However burning biomass pellets does create more issues. For example many biomass pellets will create a higher ash content than wood pellets, between the 7-10% range. Hemp however is the exception, with an ash content below 3%. Other issues revolve around corrosion and clinker and slag issues. Many biomass materials produce high levels of chloride during combustion, which is a high temperature corrosive, and can damage stoves and boilers. Clinker formations can also occur in the burn pot, and slag can collect around the heat exchanger tubes. For more information on which stoves and boilers can efficiently burn biomass pellets, please visit the:

Wood Pellet Stove and Boiler Guide

Pellet Mill

The pellet mill is obviously the key piece of equipment in pellet making. Once the material has been prepared appropriately, it is feed at controlled rates into the pellet mill. The pellet mill either comprises of a flat die or ring die design, however both designs have a die and two or more rollers rotating against the surface of the die. The speed of the pellet mill die, die hole angels, die depth and roller height play crucial roles on the quality of pellets that are produced. Pellet making is a technically demanding process to achieve quality pellets, an efficient and reliable process with lowest power consumption.

The Wood Pellet Production Guide © PelHeat Ltd - Pellet Making