Biomass Pelletisation Process and Maintain Stability Wood Pellets Production Plant

The characteristics of biomass will determine production processes including die shapes and characteristics of wood pellets product. Woody biomass is the most common and popular biomass of the biomass pelletisation. Die shape can not be common or generic for all types of biomass because it has its own characteristics. The efficient pelleting process will be produced pellets product with the amount of powder or fine which is very little, that is meaning almost all the particles of the material that is fed into the pelletiser converted into pellets. Judging sequence of processes that occur in the pelletiser, the biomass will have the following things before finally formed into pellets.

A number of materials from a particular timber, there is an expanding again when exiting from the pelletiser or in general the compaction equipmnent. This phenomenon is more easily seen in briquettes because it was bigger than pellets. This happens because these materials absorb more air from the atmosphere to add moisture to the pellets or briquettes, whereas when the particle material into the die in the presence of strong pressure and high temperature, the amount of water vapor in the particles of the material will come out and so is lignin serves as the glue will come out at this stage.

On the specifics of wood pellets also there is little difference of quality, logistics and consumer needs between Europe and the United States. The difference between the others, especially that on wood pellets for the European market generally use a die with a size of 6 mm, while for the US market generally use the die to the size of a quarter inch or 6.35 mm or it could be using equipment that is more suitable, for example, to adjust to the European, EN method while the Americans with ASTM method. But the different sectors also allows the use of different pellet sizes. Most retailers in Europe using a 6 mm pellet size, so that when using the US standard with the size of a quarter inch or 6.35 mm and after production also will typically expand to 6.5 mm making the European market less acceptable. In addition the European market also liked the wood pellets with a length of 1.5 to 2 cm, so it is not too short and not too long. Durability is also an important factor for the target market, the European issuing durability requirements limit is 97.5 primarily for industrial bulk market, but for the bulk of residential delivery majority of distributors are looking for products with a durability from 98.5 to 99.0. This is because the residential delivery typically use pneumatic conveyor and the strong desire to reduce fine (powder).

The market target aso will determine how the process of the production of wood pellets. Asian markets with relatively new age do not yet qualify as strict as Europe or America with the target users are also a number of differences. A large number of requests with strict quality also makes the need for reliable equipment or machinery becomes absolutely necessary. A number of manufacturers pelletiser for wood pellets has also been applying heat sensor technology at the pelletiser that they make as an option for the producers of wood pellets. This technology includes installation of high heat sensor directly on a roller to monitor in real time the critical temperature. The intended use of these technologies is to reduce downtime and accidents caused by overheating on the roller and the bearing shaft so that production targets can be achieved more easily.

As for supplies of raw material supply of wood pellets, wood sawmill wastes and wood processing wastes could be used but the energy plantations or forests  will be the best choice, especially for long-term orientation. Good forest management service that will produce a sustainable supply of raw materials. Optimizing the use of land in a number of locations, the selection of appropriate plant species and supported tropical climate conditions that support are some of the things that support the integration of energy plantation or forest with wood pellet business. Because of the availability of raw materials is one of the key success factors in the business of wood pellets, so it needs special attention of its own.

Optimization The Pelletiser Perfomance

Carpet is a thin layer of material that is pressed, which are at the peak of the die surface. When the incoming raw materials into pelletiser it will be driven by the roller and forming carpet. The more materials put into pelletiser it will further add to the carpet. Carpet is then pressed into the die holes and produce pellets. So for material that can form a pellet, initially to be able to form a carpet.

All wood pellet production is a matter of reducing energy requirements and the degree of wear of equipment while simultaneously improving quality and productivity of the pellets. This is why the production of quality pellets require special skills. Setting between roller and die with a certain distance which is called the roller gap that is essential for the above purpose. Characteristics of raw materials such as density and bonding ability are other parameters that need to be considered. Roller gap can be set at a certain distance so that the pelletiser performance will optimal. Generally, gap 1 mm is the optimum condition, but the gap variation can be tried for the specific conditions of certain raw materials.

On hole die if we look deeper , it turns out is also not a form of cylindrical holes from the tip to the hilt . These conditions also deliberately designed so that the densification process can be optimal . If the shape of the tip is widened at the inlet of the die wear and missing then the quality of pellets produced will decline even not formed pellets . Comparison of length ( L ) and diameter ( D ) on the die hole according to the characteristics of raw materials will result in optimal performance . Selection of an appropriate metal material will make the pelleting process can be done economically . The quality of metal and metal working to die makes no domestic manufacturers are making in Indonesia. Another factor in has not many wood pellet producers in Indonesia may also be a factor in the reluctance of domestic manufacturers to make dies for wood / biomass pellets. But as the needs of wood pellet or pellet fuel increasingly skyrocketing then the above is possible.

Die and Roller in Pelletiser

Pelletiser is the heart of the production of wood pellets. The quality and quantity of products of wood pellets is mainly determined by this equipmnent. Quality equipment of pelletiser itself is determined by the ability to produce wood pellets according to specifications or international standards. More and more product of wood pellets are produced or the longer lifespan (life) of pelletiser it indicates good quality. After going through the boundary of the capacity or useful life of the pelletiser to be replaced because it is no longer effective when continuously used. As a benchmark cost for this pelletiser range from Rp 40-75, -/kg wood pellets, including good category.

Pelletiser which is the principle of compression or suppression of material by the roller into the mold (die) to form wood pellets. The high friction on the roller and die on the raw materials and the heat causes the temperature of the metal wear faster. The greater the friction the more dense wood pellet produced  or hard but metal material of pelletiser wear faster. The quality of the metal material in the die and roller of pelletiser and pelletiser design itself contributes greatly to the performance and life of the pelletiser.

Currently there are two kinds pelletiser commonly used in the production process of wood pellet flat die and ring die. The flat die design simpler, commonly used for woodpellet production in small capacity, its history  adopted from animal feed pellet machine. While the type of ring die is a more advanced design, the technique of making it more difficult than further development of the type flat die and commonly used  in production of wood pellets medium-large scale.