A series of experiments have been performed in a pellet mill, to
optimize the moisture content needed for densification of barley
straw at two different particle size reduction rates. The effect of the
pelletizing process on the physicochemical properties of the raw
material, and the effect of pine addition on the quality of blended
pellets have been studied as well. The conclusions obtained in this
work can be summarized as follows:
– No enhancement was found in compaction after pelletizing barley
straw ground to pass mill screens of 4 and 7 mm.
– The highest mechanical durability reached for barley straw pellets
was 95.5%, with final pellet moisture of 6–8%, when ground straw
was first moistened to the rage of 19–23% of water (wt/wt, wet
basis). Pellets with low durability and a lot of fines result when
moistening below this range and, if no water is added, then no
compaction occurs at all.
– Properties related to the degree of agglomeration, such as the
mechanical durability and the pellet length, increase with the
straw moisture content. The pellet density, more related to
compaction, seems to decrease with the moisture content. Longer
pellets exhibit higher durability, but higher density is not a
warranty of higher durability.
– Pelletization of the raw material resulted in a small decrease of the
net heating value of barley straw.
– The mechanical durability of pellets was enhanced over one point
when the barley straw was blended with pine sawdust (2, 7 and
12 wt.%), adjusting the moisture content to 12% in the mixture.
Better mechanical durability is reached and, for its high lignin
content, the calorific value increases with pine addition. However,
the ash content is still very high in the blended pellets (10%),
exceeding the value of 5% allowed for A1 class in the European
norm for non-woody pellets for non-industrial use
A series of experiments have been performed in a pellet mill, tooptimize the moisture content needed for densification of barleystraw at two different particle size reduction rates. The effect of thepelletizing process on the physicochemical properties of the rawmaterial, and the effect of pine addition on the quality of blendedpellets have been studied as well. The conclusions obtained in thiswork can be summarized as follows:– No enhancement was found in compaction after pelletizing barleystraw ground to pass mill screens of 4 and 7 mm.– The highest mechanical durability reached for barley straw pelletswas 95.5%, with final pellet moisture of 6–8%, when ground strawwas first moistened to the rage of 19–23% of water (wt/wt, wetbasis). Pellets with low durability and a lot of fines result whenmoistening below this range and, if no water is added, then nocompaction occurs at all.– Properties related to the degree of agglomeration, such as themechanical durability and the pellet length, increase with thestraw moisture content. The pellet density, more related tocompaction, seems to decrease with the moisture content. Longerpellets exhibit higher durability, but higher density is not awarranty of higher durability.– Pelletization of the raw material resulted in a small decrease of thenet heating value of barley straw.– The mechanical durability of pellets was enhanced over one pointwhen the barley straw was blended with pine sawdust (2, 7 and12 wt.%), adjusting the moisture content to 12% in the mixture.Better mechanical durability is reached and, for its high lignincontent, the calorific value increases with pine addition. However,the ash content is still very high in the blended pellets (10%),exceeding the value of 5% allowed for A1 class in the Europeannorm for non-woody pellets for non-industrial use
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