Density of compacted herbaceous stalk materials
2008
Kronbergs, E., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Engineering. Inst. of Mechanics | Smits, M., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Engineering. Inst. of Mechanics
The 2003 reform of the EU Common agricultural policy introduced a special 'energy crop payment' under which a premium of 45 euro per hectare is available for the production of energy crops. There is possibility in Latvia to provide for the use of approximately 0.36 million ha of the unused now agricultural land for energy crop growing. There are others resources of bioenergy in Latvia as agricultural residues and peat. More than 230 million tones of peat are available for solid biofuel production. Peat can be used as additive for manufacturing of briquettes, because it improves density of herbaceous material briquettes. European countries have standards (ONORM 7135, SS 18 71 20 and DIN 51731) concerned with wood pellet and briquette properties. Compacting is necessary operation for solid biofuel production from herbaceous stalk materials because the density of dry herbaceous stalk materials (straw, reeds) is too low (20-60 kg mE-3) for transportation on long distances. For density determination of compacted biomass different methods were approved and evaluated. Compacting experiments have been carried out in closed die by means of hydraulic press equipment. Maximum pressure 2330 bar was in closed die. Different roughness stalk material particle briquettes had been obtained. Compositions of particles from roughness group 2-3 mm and group with size less, than 0.25 mm in different weight proportions let obtain density is greater than 1.0 kg dm-3 in briquetting, if content of finest particles is greater than 30 %. The same density (1.0 kg dmE-3) has been obtained in densification of straw stalk particle fraction 2-3 mm and peat particle is less than 3 mm composition, if content of peat is less than 20 %. It can be concluded, that fine chopping of stalk materials significantly influence briquetting density.
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