U.S. patent application number 12/907526 was filed with the patent office on 2011-10-27 for engineered plant biomass feedstock particles.
This patent application is currently assigned to FOREST CONCEPTS, LLC. Invention is credited to Thomas F. Broderick, James H. Dooley, David N. Lanning.
Application Number | 20110262687 12/907526 |
Document ID | / |
Family ID | 44729929 |
Filed Date | 2011-10-27 |
United States Patent
Application |
20110262687 |
Kind Code |
A1 |
Dooley; James H. ; et
al. |
October 27, 2011 |
ENGINEERED PLANT BIOMASS FEEDSTOCK PARTICLES
Abstract
A novel class of flowable biomass feedstock particles with
unusually large surface areas that can be manufactured in
remarkably uniform sizes using low-energy comminution techniques.
The feedstock particles are roughly parallelepiped in shape and
characterized by a length dimension (L) aligned substantially with
the grain direction and defining a substantially uniform distance
along the grain, a width dimension (W) normal to L and aligned
cross grain, and a height dimension (H) normal to W and L. The
particles exhibit a disrupted grain structure with prominent end
and surface checks that greatly enhances their skeletal surface
area as compared to their envelope surface area. The L.times.H
dimensions define a pair of substantially parallel side surfaces
characterized by substantially intact longitudinally arrayed
fibers. The W.times.H dimensions define a pair of substantially
parallel end surfaces characterized by crosscut fibers and end
checking between fibers. The L.times.W dimensions define a pair of
substantially parallel top surfaces characterized by some surface
checking between longitudinally arrayed fibers. The feedstock
particles are manufactured from a variety of plant biomass
materials including wood, crop residues, plantation grasses, hemp,
bagasse, and bamboo.
Inventors: |
Dooley; James H.; (Federal
Way, WA) ; Lanning; David N.; (Federal Way, WA)
; Broderick; Thomas F.; (Lake Forest Park, WA) |
Assignee: |
FOREST CONCEPTS, LLC
Auburn
WA
|
Family ID: |
44729929 |
Appl. No.: |
12/907526 |
Filed: |
October 19, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61343005 |
Apr 22, 2010 |
|
|
|
12907526 |
|
|
|
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Current U.S.
Class: |
428/114 |
Current CPC
Class: |
Y10T 428/24132 20150115;
Y10T 428/298 20150115; Y10T 428/2982 20150115; B27L 11/02
20130101 |
Class at
Publication: |
428/114 |
International
Class: |
B32B 5/12 20060101
B32B005/12 |
Goverment Interests
STATEMENT OF GOVERNMENT LICENSE RIGHTS
[0002] This invention was made with government support by the Small
Business Innovation Research program of the U.S. Department of
Energy, Contract SC0002291. The government has certain rights in
the invention.
Claims
1. A bioenergy feedstock material consisting of a multiplicity of
roughly parallelepiped shaped particles of a plant biomass material
having fibers aligned in a grain, wherein the particles are
characterized by consistent piece size uniformity, wherein each
particle has a length dimension (L) aligned substantially with the
grain and defining a substantially uniform distance along the
grain, a width dimension (W) normal to L and aligned cross grain,
and a height dimension (H) normal to W and L, and wherein the
L.times.H dimensions define a pair of substantially parallel side
surfaces characterized by substantially intact longitudinally
arrayed fibers, the W.times.H dimensions define a pair of
substantially parallel end surfaces characterized by crosscut
fibers and end checking between fibers, and the L.times.W
dimensions define a pair of substantially parallel top
surfaces.
2. The bioenergy feedstock material of claim 1, wherein L is
aligned within 30.degree. parallel to the grain.
3. The bioenergy feedstock material of claim 2, wherein L is
aligned within 10.degree. parallel to the grain.
4. The bioenergy feedstock material of claim 1, wherein H does not
exceed a maximum from 1 to 16 mm, W is between 1 mm and 1.5.times.
the maximum H, and L is between 0.5 and 20.times. the maximum
H.
5. The bioenergy feedstock material of claim 1, wherein L is
between 4 and 70 mm, and each of W and H is equal to or less than
L.
6. The bioenergy feedstock material of claim 1, wherein at least
80% of the particles pass through a 1/4 inch screen having a 6.3 mm
nominal sieve opening but are retained by a No. 10 screen having a
2 mm nominal sieve opening.
7. The bioenergy feedstock material of claim 1, wherein at least
90% of the particles pass through a 1/4 inch screen having a 6.3 mm
nominal sieve opening but are retained by a No. 4 screen having a
4.75 mm nominal sieve opening.
8. The bioenergy feedstock material of claim 1, wherein at least
90% of the particles pass through a No. 4 screen having a 4.75 mm
nominal sieve opening screen but are retained by a No. 8 screen
having a 2.36 mm nominal sieve opening.
9. The bioenergy feedstock material of claim 1, wherein at least
90% of the particles pass through a No. 8 screen having a 2.36 mm
nominal sieve opening but are retained by a No. 10 screen having a
2 mm nominal sieve opening.
10. The bioenergy feedstock material of claim 1, wherein at least
10% of the particles sink in water following stirring at 250 RPM
for 15 minutes at 25.degree. C.
11. The bioenergy feedstock material of claim 1, wherein the plant
biomass material is selected from among wood, crop residues,
plantation grasses, hemp, bagasse, and bamboo.
12. The bioenergy feedstock material of claim 6, wherein the
particles exhibit an experimental temperature compensated
conductivity (CC) of greater than 8 .mu.S as determined by the
following experimental steps: measure an initial CC of 500 ml of
distilled water at 25.degree. C. in a glass vessel, add 10 g of the
particles into the water, stir the particles at 250 RPM in the
water at 25.degree. C. for 30 min, measure the CC of the water at
30 min, and calculate the experimental CC by subtracting the
initial CC from the CC at 30 minutes and thereby determine that the
calculated experimental CC of the particles is greater than 8
.mu.S.
13. The bioenergy feedstock material of claim 12, wherein the
calculated experimental CC of the particles is greater than 10
.mu.S.
14. The bioenergy feedstock material of claim 12 wherein the
calculated experimental CC of the particles is greater than 12
.mu.S.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from provisional
application No. 61/343,005 filed Apr. 22, 2010.
FIELD OF THE INVENTION
[0003] Our invention relates to manufactured particles of plant
biomass useful as bioenergy feedstocks.
BACKGROUND OF THE INVENTION
[0004] Wood particles, flakes, and chips have long been optimized
as feedstocks for various industrial uses (see, e.g., U.S. Pat.
Nos. 2,776,686, 4,610,928, 6,267,164, and 6,543,497), as have
machines for producing such feedstocks.
[0005] Optimum feedstock physical properties vary depending on the
product being produced and/or the manufacturing process being fed.
In the case of cellulosic ethanol production, the feedstock should
be comminuted to a cross section dimension of less than 6 mm for
steam or hot water pretreatment, and to less than 3 mm for
enzymatic pretreatment. Uniformity of particle size is known to
increase the product yield and reduce the time of pretreatment.
Uniformity of particle size also affects the performance of
subsequent fermentation steps. Piece length is also important for
conveying, auguring, and blending. Over-length pieces may tangle or
jam the machinery, or bridge together and interrupt gravity flow.
Fine dust-like particles tend to fully dissolve in pretreatment
processes, and the dissolved material is lost during the washing
step at the end of preprocessing.
[0006] Particle shape can be optimized to enhance surface area,
minimize diffusion distance, and promote the rate of chemical or
enzyme catalyst penetration through the biomass material.
[0007] Gasification processes that convert biomass to syngas
present a different set of constraints and tradeoffs with respect
to optimization of particle shape, size, and uniformity. For such
thermochemical conversions, spherical shapes are generally favored
for homogeneous materials, and enhancement of surface area is less
important. Cellulosic plant derived feedstocks are not homogeneous,
and thus optimal properties involve complex tradeoffs.
[0008] A common concern in producing all bioenergy feedstocks is to
minimize fossil fuel consumption during comminution of plant
biomass to produce the feedstock.
SUMMARY OF THE INVENTION
[0009] Herein we describe a novel class of flowable biomass
feedstock particles with unusually large surface area to volume
ratios that can be manufactured in remarkably uniform sizes using
low-energy comminution techniques. The feedstock particles are
roughly parallelepiped in shape and characterized by: a length
dimension (L) aligned substantially with the grain and defining a
substantially uniform distance in the grain direction; a width
dimension (W) normal to L and aligned cross grain; and a height
dimension (H) normal to W and L. The particles exhibit a disrupted
grain structure with prominent end and surface checks that greatly
enhance their skeletal surface area as compared to their envelope
surface area. Representative wood feedstock particles of the
invention are shown in FIG. 1B, which indicates how the nominal
parallelepiped shape of the particles is cracked open by pronounced
checking that greatly increases surface area. The L.times.H
dimensions define a pair of substantially parallel side surfaces
characterized by substantially intact fibers arrayed along the
grain. The W.times.H dimensions define a pair of substantially
parallel end surfaces characterized by crosscut fibers and end
checking between fibers. The L.times.W dimensions define a pair of
substantially parallel top surfaces characterized by some surface
checking between longitudinally arrayed fibers. The feedstock
particles can be manufactured from a variety of plant biomass
materials including wood, crop residues, plantation grasses, hemp,
bagasse, and bamboo.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a photograph of similarly sized (A) prior art wood
cubes typical of coarse sawdust or chips, and (B) wood feedstock
particles of the present invention;
[0011] FIG. 2 is a perspective view of a prototype rotary bypass
shear machine suitable to produce plant biomass feedstock particles
of the present invention; and
[0012] FIG. 3 is a graph of ion conductivity leachate data from
cubes and particles like shown in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] We have applied engineering design principles to develop a
new class of plant biomass feedstock particles characterized by
consistent piece size uniformity, high skeletal surface area, and
good flow properties. The feedstock particles can be conveniently
manufactured from a variety of plant biomass materials at
relatively low cost using low-energy comminution processes.
[0014] The term "plant biomass" as used herein refers generally to
encompass all plant materials harvested or collected for use as
industrial feedstocks, including woody biomass, hardwoods and
softwoods, energy crops like switchgrass, Miscanthus, and giant
reed grass, hemp, bagasse, bamboo, and agricultural crop residues,
particularly corn stover.
[0015] The term "grain" as used herein refers generally to the
arrangement and longitudinally arrayed direction of fibers within
plant biomass materials. "Grain direction" is the orientation of
the long axis of the dominant fibers in a piece of plant biomass
material.
[0016] The terms "checks" or "checking" as used herein refer to
lengthwise separation and opening between plant fibers in a biomass
feedstock particle. "Surface checking" may occur on the lengthwise
surfaces a particle (that is, on the L.times.H and L.times.W
surfaces); and "end checking" occurs on the cross-grain ends
(W.times.H) of a particle.
[0017] The term "skeletal surface area" as used herein refers to
the total surface area of a biomass feedstock particle, including
the surface area within open pores formed by checking between plant
fibers. In contrast, "envelope surface area" refers to the surface
area of a virtual envelope encompassing the outer dimensions the
particle, which for discussion purposes can be roughly approximated
to the particle's extent volume. Thus, the envelope surface area is
equal to the skeletal surface area minus the surface area within
checks and other open pores of the particle.
[0018] The terms "temperature calibrated conductivity," "calibrated
conductivity," and "CC" as used herein refer to a measurement of
the conductive material in an aqueous solution adjusted to a
calculated value which would have been read if the sample had been
at 25.degree. C.
[0019] The term "sinking" as opposed to "floating" is used herein
to characterize feedstock particles that sink in distilled water
following stirring at 250 RPM for 15 minutes at 25.degree. C.
[0020] The new class of plant biomass feedstock particles described
herein can be readily optimized for various conversion processes
that produce bioenergy, biofuel, and bioproducts.
[0021] Each particle is intended to have a specified and
substantially uniform length along the grain direction, a width
tangential to the growth rings (in wood) and/or normal to the grain
direction, and a height (thickness in the case of veneer) radial to
the growth rings and/or normal to the width and L dimensions.
[0022] We have found it very convenient to use wood veneer from the
rotary lathe process as a raw material. Peeled veneer from a rotary
lathe naturally has a thickness that is oriented with the growth
rings and can be controlled by lathe adjustments. Moreover, within
the typical range of veneer thicknesses, the veneer contains very
few growth rings, all of which are parallel to or at very shallow
angle to the top and bottom surfaces of the sheet. In our
application, we specify the veneer thickness to match the desired
wood particle height (H) to the specifications for a particular
conversion process.
[0023] The veneer may be processed into particles directly from a
veneer lathe, or from stacks of veneer sheets produced by a veneer
lathe. Plant biomass materials too small in diameter or otherwise
not suitable for the rotary veneer process can be sliced to
pre-selected thickness by conventional processes. Our preferred
manufacturing method is to feed the veneer sheet or sliced
materials into a rotary bypass shear with the grain direction
oriented across and preferably at a right angle to the machine's
processing head.
[0024] The rotary bypass shear that we designed for manufacture of
wood feedstock particles is a shown in FIG. 2. This prototype
machine 10 is much like a paper shredder and includes parallel
shafts 12, 14, each of which contains a plurality of cutting disks
16, 18. The disks 16, 18 on each shaft 12, 14 are separated by
smaller diameter spacers (not shown) that are the same width or
greater by 0.1 mm thick than the cutting disks 16, 18. The cutting
disks 16, 18 may be smooth 18, knurled (not shown), and/or toothed
16 to improve the feeding of veneer sheets 20 through the
processing head 22. Each upper cutting disk 16 in our rotary bypass
shear 10 contains five equally spaced teeth 24 that extend 6 mm
above the cutting surface 26. The spacing of the two parallel
shafts 12, 14 is slightly less than the diameter of the cutting
disks 16, 18 to create a shearing interface. In our machine 10, the
cutting disks 16, 18 are approximately 105 mm diameter and the
shearing overlap is approximately 3 mm.
[0025] This rotary bypass shear machine 10 used for demonstration
of the manufacturing process operates at an infeed speed of one
meter per second (200 feet per minute). The feed rate has been
demonstrated to produce similar particles at infeed speeds up to
2.5 meters per second (500 feet per minute).
[0026] The width of the cutting disks 16, 18 establishes the length
of particles produced since the veneer 20 is sheared at each edge
28 of the cutters 16, 18 and the veneer 20 is oriented with the
fiber grain direction across the cutter disks 16, 18 parallel to
the cutter shafts 12, 14. Thus, wood particles from our process are
of much more uniform length than are particles from shredders,
hammer mills and grinders which have a broad range of random
lengths. The desired and predetermined length of particles is set
into the rotary bypass shear machine 10 by either installing
cutters 16, 18 having widths equal to the desired output particle
length or by stacking assorted thinner cutting disks 16, 18 to the
appropriate cumulative cutter width.
[0027] Fixed clearing plates 30 ride on the rotating spacer disks
to ensure that any particles that are trapped between the cutting
disks 16, 18 are dislodged and ejected from the processing head
20.
[0028] We have found that the wood particles leaving the rotary
bypass shear machine 10 are broken (or crumbled) into short widths
due to induced internal tensile stress failures that are typically
aligned with winter- and summer-wood rings. Thus the resulting
particles are of generally uniform length along the wood grain, and
of a uniform thickness (when made from veneer), but vary somewhat
in width principally associated with the microstructure and natural
growth properties of the raw material species. Most importantly,
frictional and Poisson forces that develop as the biomass material
20 is sheared across the grain at the cutter edges 28 tend to
create end checking that greatly increases the skeletal surface
areas of the particles.
[0029] The output of the rotary bypass shear 10 may be used as is
for some conversion processes such as densified briquette
manufacture, gasification, or thermochemical conversion. However,
many end-uses will benefit if the particles are screened into
narrow size fractions that are optimal for the end-use conversion
process. In that case, an appropriate stack of vibratory screens or
a tubular trommel screen with progressive openings can be used to
remove those particles that are larger or smaller than desired.
[0030] In the event that the feedstock particles are to be stored
for an extended period or are to be fed into a conversion process
that requires very dry feedstock, the particles may be dried prior
to storage, packing or delivery to an end user.
[0031] To date we have used this prototype machine 10 to make
feedstock particles in 3/16'' and 3/4'' lengths from a variety of
plant biomass materials, including: peeled softwood and hardwood
veneers ( 1/10'' and 1/6''); sawed softwood and hardwood veneers;
crushed softwood and hardwood branches and limbs; hog fuel; corn
stover; switchgrass; and bamboo. The L.times.W surfaces of peeled
veneer particles appear to retain the tight-side and loose-side
characteristics of the raw material. Crushed wood and fibrous
biomass mats are also suitable starting materials, provided that
all such biomass materials are aligned across the cutters 16, 18
substantially parallel to the grain direction, and preferably
within 10.degree. and at least within 30.degree. parallel to the
grain direction.
[0032] We currently consider the following size ranges as
particularly useful biomass feedstocks: (1) H should not exceed a
maximum from 1 to 16 mm, in which case W is between 1 mm and
1.5.times. the maximum H, and L is between 0.5 and 20.times. the
maximum H; or (2) preferably, L is between 4 and 70 mm, and each of
W and L is equal to or less than L. More preferably, for
flowability and high surface area to volume ratios, the L, W, and H
dimensions are selected so that at least 80% of the particles pass
through a 1/4 inch screen having a 6.3 mm nominal sieve opening but
are retained by a No. 10 screen having a 2 mm nominal sieve
opening. Most preferably, for uniformity as reaction substrates, at
least 90% of the particles should pass through either: (1) a 1/4''
screen having a 6.3 mm nominal sieve opening but are retained by a
No. 4 screen having a 4.75 mm nominal sieve opening; or (2) a No. 4
screen having a 4.75 mm nominal sieve opening but are retained by a
No. 8 screen having a 2.36 mm nominal sieve opening; or (3) a No. 8
screen having a 2.36 mm nominal sieve opening but are retained by a
No. 10 screen having a 2 mm nominal sieve opening.
[0033] Surprisingly significant percentages of the above
most-preferably sized wood particles readily sink in water, and
this presents the prospect of selectively sorting lignin-enriched
particles (by gravity and/or density) and more economical
preprocessing.
[0034] The following laboratory experiments demonstrate these and
other unusual and commercially valuable properties of this new
class of biomass feedstock particles.
EXAMPLES
Ion Conductivity Leachate Experiments
[0035] Buckmaster recently evaluated electrolytic ion leakage as a
method to assess activity access for subsequent biological or
chemical processing of forage or biomass. (Buckmaster, D. R.,
Assessing Activity Access of forage or biomass, Transactions of the
ASABE, 51(6):1879-1884, 2008.) He concluded that ion conductivity
of biomass leachate in aqueous solution was directly correlated
with activity access to plant nutrients within the biomass
materials for subsequent biological, chemical, or even combustion
processes.
[0036] In the following experiments, we compared leachate rates
from various types of wood feedstocks.
[0037] Materials
[0038] Wood particles of the present invention were manufactured as
described in above described machine 10 using 3/16'' wide cutters
from a knot-free sheet of Douglas fir 1/6'' thick veneer (10-15%
moisture content). The resulting feedstock was size screened, and a
10 g experimental sample was collected of particles that in all
dimensions passed through a 1/4'' screen (nominal sieve opening 6.3
mm) but were retained by a No. 4 screen (nominal sieve opening 4.75
mm). Representative particles from this experimental sample (FS-1)
are shown in FIG. 1B.
[0039] Similarly sized cubes indicative of the prior art were cut
from the same veneer sheet, using a Vaughn.RTM. Mini Bear Saw.TM.
Model BS 150D handsaw. The sheet was cut cross-grain into
approximately 3/16'' strips. Then each strip was gently flexed by
finger pressure to break off roughly cube-shaped particles of
random widths. The resulting feedstock was size screened, and a 10
g control sample was collected of particles that in all dimensions
passed through the 1/4'' screen but were retained by the No. 4
screen. Representative cubes from this control sample (Cubes-1) are
shown in FIG. 1A.
[0040] The outer (extent) length, width, and height dimensions of
each particle in each sample were individually measured with a
digital caliper and documented in table form. Table 1 summarizes
the resulting data.
TABLE-US-00001 TABLE 1 Samples (10 g) Number of pieces Length (L)
Width (W) Height (H) Control cubes n = 189 Mean 5.5 Mean 5.0 Mean
3.9 (Cubes-1) SD 0.48 SD 1.17 SD 0.55 Experimental n = 292 Mean 5.3
Mean 5.8 Mean 3.3 particles (FS-1) SD 0.74 SD 1.23 SD 0.82
[0041] The Table 1 data indicates that the extent volumes of these
size-screened samples were not substantially different.
Accordingly, the cubes and particles had roughly similar envelope
surface areas. Yet the 10 gram experimental sample contained 54%
(292/189) more pieces than the 10 gram control sample, which
equates to a mean density of 0.34 g/particle (10/292) as compared
to 0.053 g/cube. FIG. 1 indicates that the roughly parallelepiped
extent volumes of typical particles (1B) contain noticeably more
checks and air spaces than typical cubes (1A). These differences
demonstrate that the feedstock particles of the invention had
significantly greater skeletal surface areas than the control cubes
indicative of prior art coarse sawdust and chips. One would thus
expect the particles to exhibit more ion leachate than the cubes in
aqueous solution.
[0042] Individual handling during the caliper measurements tended
to beat up the Table 1 particles (FS-1), and so a second set of 10
g samples of cubes (Cubes-2) and particles (FS-2) were made as
described above from another sheet of veneer for ion conductivity
leachate assessments as described below.
Equipment
[0043] Jenco.RTM. Model 3173/3173R
Conductivity/Salinity/TDS/Temperature Meter
[0044] Corning.RTM. Model PC-420 Laboratory Stirrer/Hot Plate
[0045] Aculab.RTM. Model VI-1200 Balance
Methods
[0046] Ion conductivity of biomass leachate in aqueous solution was
assessed for each of the samples by the following protocol:
[0047] (1) Measure the initial temperature compensated conductivity
(CC, in microSiemens (.mu.S)) of 500 ml of distilled water
maintained at .about.25.degree. C. in a glass vessel.
[0048] (2) Add a 10 g sample of feedstock pieces into the water,
and stir the pieces at 250 RPM in the water at .about.25.degree. C.
for 60 minutes.
[0049] (3) Briefly stop stirring and measure the CC of the water at
15-minute intervals; and note if any of the pieces sink to the
bottom of the vessel during these brief non-stirring intervals.
[0050] (4) Calculate an experimental CC value for comparison
purposes by subtracting the initial CC from the CC at 30
minutes.
Results
[0051] The resulting CC data is shown in Table 2 and blotted FIG.
3.
TABLE-US-00002 TABLE 2 Temperature Calibrated Conductivity (.mu.S)
Sample 0 min 15 min 30 min 45 min 60 min Control cubes 1.9 6.7 8.6
9.8 10.8 (Cubes-2) Experimental 1.9 12.0 15.0 16.5 17.8 particles
(FS-2)
[0052] These results indicate that the particles exhibited nearly
twice the activity index of similarly sized cubes that generally
lacked the cross-grain end checking that characterizes the biomass
feedstocks of the invention.
[0053] In addition, all of the cubes were observed to consistently
float throughout the 60 min soak and swirl period. In contrast, a
noticeable proportion of the experimental particles sank when the
stir bar was turned off during the CC measurements.
[0054] These results are consistent with our other experimental
observations to date, as summarized in the following Table 3.
TABLE-US-00003 TABLE 3 Temperature Calibrated Conductivity (.mu.S)
Sample 0 15 30 45 60 Float Sink Size # min min min min min % % Pass
1/4'' 009/4a 1.9 9.6 11.8 screen & 009/4b 2.0 10.7 13.1
retained 0124h 2.0 7.6 9.1 9.9 84 16 by #4 012/4m 1.8 6.3 7.6 8.5
87.5 12.5 screen 014/4Cr 2.0 8.0 9.7 10.6 71 29 016/4sp 2.3 6.8 8.2
9.0 92 8 Cubes-1 2.3 4.8 5.8 6.4 100 0 Cubes-2 1.9 6.7 8.6 9.8 10.8
100 0 FS-2 1.9 12.0 15.0 16.5 17.8 Pass 009/8a 1.9 10.9 13.2 14.5
15.7 No. 4, 009/8b 2.0 11.5 14.1 15.7 16.6 No. 8 012/8h 1.8 7.1 8.5
9.4 73 27 retain 012/8m 2.0 7.6 9.1 9.9 77 23 014/Cr 2.3 10.3 12.6
13.9 51 49 No. 8/ 012/10h 1.9 9.5 11.2 12.1 52 48 No. 10 012/10m
1.9 9.2 11.0 11.8 52 48
[0055] Referring to Table 3, the #009 samples were made from 1/10''
Douglas fir veneer, and the other particle samples which were made
from 1/6'' Douglas fir veneer, as were the Cubes-1 and Cubes-2
samples.
[0056] While the preferred embodiment of the invention has been
illustrated and described, it will be appreciated that various
changes can be made therein without departing from the spirit and
scope of the invention.
* * * * *