Biomass Pellet Mill

Biomass is a general term used to describe any organic material which can be used as a fuel. For example wood, wood waste, energy crops and agricultural waste such as straw. A biomass pellet mill has variable features that make it possible to process various biomass materials. For example the pellet mill must have sufficient power to process woody biomass, and also the ability to control features such as die speed. At PelHeat we develop small mobile biomass pellet mills to process a wide range of biomass materials. The uses for these pellets could be as fuel, animal feed, animal bedding and even cooking pellets. A biomass pellet mill is a general term to describe a pellet mill, however some pellet mills have specific features for processing certain materials.

Grass Pellet Mill

Grass pellet mills are used predominantly in the animal feed industry. Grass pellet mills generally have a higher die speed than wood pellet mills for example. Also energy consumption is much lower, due to the reduced resistance of the grass.

Wood Pellet Mill

One of the key differences with wood pellet mills is the difference in die rotation speed. Wood has a much higher density than grass for example, and so is more difficult to process into pellets. More power is required to process wood into pellets, therefore traditionally a lower gearing is required to compress the wood through the die. Also to gelatinise wood into pellets, higher production temperatures are required. Raw material temperature can be increased by processing the raw material through a steam conditioner. However another way to increase pellet quality is to increase resonance time through the die, hence a lower die rotation speed.

Pellet Making

Making pellets is a process that relies on several factors with regards to the raw material and the equipment used. The raw material must have a consistent moisture content, generally within the range of 15%. The material must also be free from contaminates such as stones and metal, as these can cause serious damage to the equipment. Pellet making equipment requires a high energy input, usually requiring a three phase electrical supply. The core piece of equipment is obviously the pellet mill. Correct operation and maintenance of the pellet mill is the key factors in producing quality pellets efficiently.

Pellet Mill Production Guide

As stated there are several variables which need to be controlled to produce quality biomass pellets. Each raw material behaves differently in the pellet mill, and only by understanding the results can the process be adjusted to produce suitable quality pellets. However many people interested in how pellets are made, and possibly building their own set-up are not familiar with the details of the process.