Drying biofuel chips in a container system.
The raw material for forest chips is stored either in stockpiles at roadside landings to await chipping or the wood is transported after storage to terminals or to the end use facility for chipping. The most common method is to chip the wood at roadside landings and transport the forest chips to a power plant by wood chip truck. There are however challenges with forest chip drying if better quality is to be maintained and dry matter losses reduced during storage. The quality of fuel chips varies because the drying of the raw material is dependent on the weather. This may result in interruptions in the operation of heating plants making it necessary to use other energy sources, such as oil. Moisture in fuel chips is detrimental, as it affects heating value and the amount of energy obtained from the chips. Damp forest chips burn imperfectly, which means that emissions increase. The amount of moisture also increases transport costs. This has resulted in the need for new drying technology relating to heat production.
Luke has been involved in a project to develop an artificial dryer for drying forest chips. The project involved a dryer being constructed in a shipping container. Even though artificial dryers already exist in the market, they are often expensive and complicated. The dryer developed as part of this project had the advantages that relative to its size, the equipment is efficient, easily moveable and it is suitable for various materials, including wood chips. The first drying test was carried out using stem wood chips. The full cost-benefit of artificial drying must however still be determined.
The dryer´s energy consumption is the biggest challenge. The waste heat from heating plants could be used to run the dryer. The drying time for forest chips can decrease from months to hours or even minutes. At the same time, quality will improve, as rot no longer has time to affect the wood. Money tied up in stocks is saved when the wood is rapidly deployed and more energy is obtained from the dry fuel chips. The forest chips can be dried during milder periods and stored. Source: https://www.luke.fi/en/drying-forest-chips-using-artificial-dryer/