Issue Date: WHEN - April 2007, Posted On: 3/14/2007
New Trends In Europe For The Treatment Of Woody Biomass
Courtesy of Joachim Hirtenfellner, Komptech GmbH/ Frohnleiten (Austria)
What began on September 27th 2001 with the European Union's Renewable Energy Directive (2001/77/EC) is now being continued with the EU Commission's “Roadmap for Renewable Energy in the 21st Century†of January 10th 2007. In March 2006, the European Parliament called for the percentage of renewable energy, as part of the total energy consumption of the EU, to be increased to 25 per cent by 2020. In order to achieve these objectives, it will be necessary to make massive efforts in all sectors (power generation, heat generation, cooling and biofuels).
These efforts will be associated with widespread investment. In the heat generation sector, the European Union is banking on the enormous cost-efficient potential of biomass as concluded by the EU Commission biomass action plan dated December 7th 2005. This requirement for more renewable energy from biomass has resulted in long-term stimulation of the market for these materials. Spring 2006 in Austria saw for the first time shortfalls in the supply of wooden pellets, resulting in a sustained price increase of up to 50 per cent. The situation has since returned to normality. Supply seems now to be secure but the pricing situation has, admittedly, not improved dramatically. Despite increased production capacities, there is still huge backlog demand in order to sustainably satisfy the continually increasing demand for heating material in the long term.
Besides products already well-established, such as the pellets and wood chippings mentioned, other materials are available that stem from landscape conservation. Composting has previously been the chief method of recycling these material streams (mainly municipal green waste, bush and branch cuttings). The increased demand for heating material brings with it a new business opportunity for operators of compost plants: Using appropriate machine technology, valuable fuel for biomass generation plants can be generated alongside compost. From the source material delivered to the plant, fuel is generated either directly or following a short, intensive rotting process - depending on wood and green fraction.
KOMPTECH has just the right machine technology for all treatment stages in this process.
In the first step, dry branch-wood, root stocks, driftwood, etc. is shredded down to the size required by the generation plant. Slow-running shredding technology is used. The end result of this slow-running, cutting and shredding process is a marked reduction of the fine fraction when compared to “fast-running†systems. Resistance to contraries is also increased significantly. Screen baskets integrated into the shredding area filter out material based on the hole size of the basket. Screen baskets with mesh widths between 100mm and 250mm are deployed here. A quick-change system simplifies greatly the process of adjusting to source material and desired particle size. The CRAMBO shredder is also available as a mobile version on a 3-axle chassis or assembly on an articulated lorry including loading mechanism. These variants make possible usage across different sites as well as treatment of thinning residue at the location of origin, even in mountainous areas.
The use of this material will gain considerably in importance as a result of the huge demand for fuel in the future. The CRAMBO offers a further option - an integrated fine fraction separator for shredding materials made up of a large quantity of earth, such as rootstocks. This earth fraction (up to 50 per cent of weight in extreme cases) can be separated off in one operation.
In order to generate usable fuel fraction from fresh branch and bush cuttings, a biological decomposition process, in the form of windrow composting, is used after the pre-shredding process. Screen baskets with hole size between 180mm and 300mm are used for this pre-shredding process on the CRAMBO. The resulting coarse material structure allows a high air pore volume in the windrow body, accelerating the biological decomposition process. The windrows are turned with a triangular windrow turner from KOMPTECH, guaranteeing the rotting process. This way the majority of the green fraction decomposes and the remainder concentrates increasingly over time in the fine fraction. Biological processes during decomposition result in temperatures of 60 to 70 degrees centigrade inside the windrows. At the same time, water, in the form of steam, is discharged on each turn cycle.
The decomposition process is halted after about ten days and the material screened off.
The star screen technology used separates off fine fraction and overlengths in one operation and produces a fraction with a precise particle size. This way up to 50 per cent usable fuel fraction is generated during screening of pre-composted material. The fine fractions separated off are composted further and used afterwards as fertilisers and soil conditioners. Variations in material moisture present no problems for star screen technology from KOMPTECH. Particle size distribution can be adjusted to the desired product within seconds by changing the rotation speed of the screen stars. Wherever necessary, an integrated wind sifter separates off contaminants such as synthetic material, an iron separator separates off iron fraction using magnets and a “roll separator†separates off stones. The MULTISTAR star screen is available in various sizes either as a stationary version or a mobile version. Models M2/M3 of the mobile variant (for separation into two/three fractions) have a maximum throughput of 100m3/h. The XXL model has a maximum throughput of 400 m3/h.
Using this type of technology from KOMPTECH can not fail to improve the operating efficiency of a plant. The reasons for this are two-fold - firstly the high revenues generated by the fuel and secondly the low operating costs incurred because of the small number of process stages. Furthermore, plant throughput can be increased considerably by significantly reducing processing time.
The use of this technology on a European level can contribute in bringing closer the achievement of the ambitious objectives in regard to renewable energy sources.
