Biomedical Engineering Reference
In-Depth Information
Green
bark-
stripped
core
Retted
bark-
stripped
core
Chopped
core
Screened kenaf
core Fines
Pelleted kenaf
core powder
Figure 12.4
Woody core by-product after fiber extraction. (Courtesy of TEMAFA.)
non-woven fabrics that are increasingly employed in filtration, insulation, environmental
clean-up and vehicle interiors. Woody core and short (trash) fiber can be used as biomass
feedstock for biofuel and biochar conversion. Fiber crop seeds can be used for producing
food ingredients, nutraceutical products, cosmetic products, and technical products.
Although the harvesting technologies influence the produced fiber quality, the fiber extract-
ing process is a key step in the bast fiber production. Two important technologies currently
used in bast fiber production are described here.
One technology is a mechanical scutching line for producing line bast fiber, woody
core (shives) and seed. This processing line keeps bast fiber in its stalk length in each
process step, so that the extracted fiber is long staple fiber and can be cut into short staple
fiber, depending on the different cutting lengths required by different end uses, such as
blended textiles, non-woven felts, composites or paper. The automatic scutching line
evolved from a traditional manual operation of scutching flax using wooden blades. The
whole machine system of a scutching line usually consists of the following units: bale
opening, stalk breaking, scutching, and cutting and baling. Figure 12.5 illustrates a typical
flax scutching line.
The bale opening unit is to open delivered bales, remove seed, and make a continuous and
even layer of fiber stalk on the feed belt. These mechanical actions are performed by a bale
opener and a stalk divider. To assure processing efficiency, harvested fiber crop stalks need to
be baled parallel to each other, with stalk top on one side and stalk bottom on the other side.
The stalk breaking unit performs woody core crushing without fiber damage. This enables the
broken woody core chips (large size shives) to be separated from the fiber bundles. The
breaking unit has two modules, one for breaking fiber stalk bottom and the other for breaking
fiber stalk top. The scutching unit is used to remove woody core particles (small size shives)
remaining in the fiber bundles after the stalk breaking. In the flax scutching line as shown in
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