To manufacture biomass pellets in a highly automated process requires more than a few processes in biomass pellet plants. The first procedure is to reduce the raw matter in size. The raw matter may already be sawdust, in this case in point the sawdust can move straight on to drying. In cases where the raw material is biomass chips or logs, size reduction will have to take place before the wood can be placed in the dryer. In the biomass is already in chipped form it can be metered into a hammer mill, if not chipping will be required. In the hammer mill the hammers spin around 4000 rpm. As the hammer hits the biomass chip it shatters into smaller pieces. A screen by holes of a set size then screens the particles, for biomass pellet manufacture a particle size of 5mm is generally required for quality wood pellets.

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Once the particles of a adequate size, they are then ready to be dried down to the necessary moisture content. The two main types of dryers used are flash dryers plus rotary drum dryers. To reduce the carbon footprint of the process ideally wood should be used as the heat source for the dryer. Once the particles have been dried a fan is used to remove the particles from the dryer, as well as then a cyclone separator is used to separate the particles from the air stream. For biomass pellet production the pellet plants often have a steam conditioner. High heat steam is used to condition the sawdust before it enters the pellet mill. The heat treatment of the sawdust starts the melting process of the untreated lignin within the biomass to bind the sawdust into pellet form. The pre-melting of the lignin before the sawdust enters the pellet mill, aids in pellet quality as well as also lowers pellet mill fuel consumption. The two main pellet mill designs are the flat die pellet mill and ring die pellet mill. The flat die design is more common for small scale plants plus the sphere die design is more often used in large scale plants. The design of the pellet mill may involve either the roller shell rotating or the die rotating in both designs of pellet mill. The basic principle of the pellet mill is the raw material enters plus is compressed via a series of rollers through the die. The design of the holes in the die can influence pellet compression as well as productivity. The aim is to achieve the balance between generating pellets of a suitable quality, by way of the highest productivity probable while minimising energy consumption.

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There are unlike grades of biomass pellets produced in pellet plants. The most common wood pellet grade created is premium biomass pellet fuel. This is shaped mainly from softwood and hardwood residues from timber construction. Premium pellets demand the highest prices however the timber producers are now aware of the value of their waste, in addition to charge for the sawdust where originally they paid the pellet producers to remove the sawdust. Owing to this fact pellet producers are looking for other wood resources the can use to make biomass pellet fuel. For example willow grown as short rotation coppice is being developed.

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