Biomedical Engineering Reference
In-Depth Information
4. mineral based liquid crystal assemblies;
5. layer by layer assemblies of polyelectrolyte coatings.
The forest products industry will also be able to take advantage of the substantial appli-
cation equipment industry that has developed a number of novel machines for making
paper and applying coatings at very high speeds such as:
1. metered size press;
2. spray applicator;
3. multilayer curtain coater;
4. new applications devices yet to be determined.
1.12.6
Reducing Energy Usage and Reducing Capital Costs in Processing Wood
to Products
Priority goals for the application of nanotechnology in the forest products industry are the
reduction of energy consumption as well as reducing capital costs. These are priority
goals because conversion of wood into lignocellulosic products - lumber, engineered
wood, composites, pulp, and paper - uses considerable amounts of energy and is quite
capital intensive. This is because of: (1) the large tonnage of forest product used
annually in the US - over 205 million metric tons; (2) variability of wood as a raw
material; (3) the need for water removal from the final product; (4) many sequential
processing steps, (5) the amounts of water used in processing, (6) the need to deal with
byproduct waste streams, and (7) the fact that many of the conversion technologies have
their origins dating back from many decades to even centuries ago.
Overall energy consumption is between 2.891 EJ (2,740 trillion BTUs) and 3.511
EJ (3,272 trillion BTUs). This level of consumption represents 12-16% of US man-
ufacturing energy demand - depending upon the literature source cited. Energy use is
the second or third largest cost factor for the industry, especially as fuel and electricity
prices continue to rise. Although the industry as a whole self-generates almost 50% of its
energy needs from on-site combustion of biomass and pulping by-products, the industry
still ranks as the country's fourth largest consumer of fossil energy (American Forest
and Paper Association 2006). Paper and paperboard production accounts for the largest
share of energy use (approximately 78%) in the industry, mainly due to the amount of
energy required to evaporate the large quantities of water used to form the pulp slurry
and the paper web. Pulping (7%), engineered wood products/composites (7%), sawn
lumber (5%), and preservative treated and other lumber production (3%) uses compar-
atively less energy. However, because of the large tonnages of materials involved, the
amount of energy used is substantial.
Capital costs are also a major problem for the forest products industry. For example,
the pulp and paper industry ranks as one of the most capital-intensive industries in the
nation. Paper machines are by far the largest and most expensive capital component.
Pulping and bleaching equipment and chemical recovery plants also represent a large
share of installed capital due to their size and complexity. By-product waste stream
abatement and control are also a significant and recurring capital expense industry-wide.
The objectives for applying nanotechnology in reducing energy and capital costs are
to employ nanomaterials in forest products processing in order to reduce manufacturing
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