Note: Descriptions are shown in the official language in which they were submitted.
. . .. . .. i .... .. . .. . .. ..... . . .
CA 02639275 2008-09-03
BIOMASS PRESSURE LIQUID RECOVERY SYSTEM
This invention relates to an apparatus and method for extracting liquid
from a biomass material for removal or recovery by compaction.
BACKGROUND OF THE INVENTION
US Patent Application 2008/0057282 (Bishop) published March 6,
2008 discloses a portable biomass densifier including an auger or screw that
conveys biomass material fed into a cylinder of the auger from a tapered
hopper
above the cylinder. The auger forces the material toward a vented barrel and
compresses the material into the barrel. The vented barrel has a plurality of
elongated openings or slots therein, so that as the material is fed into the
barrel and
is further compressed, the heat and pressure of the extruder releases gasses
from
the biomass material through the slots in the barrel without requiring a
separate heat
source. The compressed material can be used as a combustion product.
UK Patent Application 2,269,131 (Clifton) published February 2, 1994
discloses a very similar arrangement.
SUMMARY OF THE INVENTION
It is one object of the invention to provide an apparatus for extracting
liquid from a biomass material for removal or recovery by compaction.
According to one aspect of the invention there is provided an
apparatus for compacting biomass material comprising:
, ,
CA 02639275 2008-09-03
2
a generally cylindrical compression barrel having a discharge opening
at one end of the compression barrel, a lead end opposite the discharge end
and a
peripheral wall;
a feed inlet opening in the peripheral wall of the compression barrel
through which the biomass material is fed in use;
a feed hopper for feeding the biomass material into the feed inlet
opening;
an auger shaft extending through the lead end of the compression
barrel and extending coaxially along the compression barrel to the discharge
end
such that rotation of the auger shaft within the compression barrel acts to
carry the
biomass materials from the feed inlet opening to the discharge end and to
apply
pressure to the biomass material as it is discharged through the discharge
end;
and a forming barrel mounted at the discharge end of the compression
barrel and arranged to receive the biomass material therefrom, the barrel
having a
series of longitudinally extending slots allowing the escape of liquid content
from the
compressed material.
Preferably the auger shaft carries a plurality of helical flights which is
preferably at least three, each having start and end positions of the flight
longitudinally spaced from the start and end of the other flight or flights
and with the
flights having outer edges at the peripheral wall of the compression barrel.
Preferably the shaft comprises a sleeve carrying the auger flight and
inner shaft with a shear pin connecting the sleeve to the inner shaft.
,
CA 02639275 2008-09-03
3
Preferably the forming barrel has an outer wall which is connected at
the discharge end and has a transverse dimension greater than that of the
compression barrel such that it is spaced outwardly of an imaginary cylinder
defined
by the peripheral wall.
Preferably the auger shaft has an end portion which projects partly into
the forming barrel so that the plurality of helical flights each have an end
portion
which projects into the forming barrel.
Preferably each of the flights has a tip portion thereon which is rotated
around the shaft axis with the flight, where the end tip portion is inclined
so that it
has an angularly leading edge and an angularly trailing edge where the
trailing edge
is located at an axially advanced position so as to pass over the laid down
material
in the forming barrel in a wiping action.
Preferably the forming barrel has a peripheral wall at least a part of
which and preferably substantially all of which is formed from a series of
parallel
longitudinally extending bars defining slots therebetween with the bars being
supported by a series of longitudinally spaced, peripherally extending ribs to
hold
them against outward movement under the pressure from the compressed biomass
material.
Preferably the spacing between the bars is of the order of or less than
0.030 inch. Such material is commercially available and is known as "wedge
wire".
Preferably there is provided a collection container surrounding the
forming barrel for collecting liquid and gases escaping from the forming
barrel. This
CA 02639275 2008-09-03
4
may act to condense any vapor and to collect any liquid to prevent the escape
into
the atmosphere and to collect the material if it has a value.
Preferably the peripheral wall of the forming barrel is defined by a
plurality of planar wall portions so as to be polygonal with each of the
planar wall
portions being formed from the parallel bars defining slots therebetween.
Preferably the forming barrel includes dividing walls extending
longitudinally and transversely of the barrel for dividing the forming barrel
and the
biomass material therein into separate portions.
Preferably the feed hopper is arranged to one side of the compression
barrel so as to feed into the side of the barrel.
Preferably the feed hopper includes an auger along a bottom of the
hopper and a pair of rotating bars each extending along the hopper on a
respective
side of the auger and parallel to the auger and each having a plurality of
outwardly
extending members for breaking bridging of the biomass material in the hopper.
Preferably the feed hopper includes an auger and at least one rotating
member for breaking bridging of the biomass material in the hopper.
Preferably there is provided an end plate on the end of the forming
chamber with an adjustable orifice which partly closes a discharge end of the
forming barrel to provide a back pressure on the biomass material in the
forming
barrel.
CA 02639275 2008-09-03
According to a second aspect of the invention there is provided a
method for extracting liquid from a biomass material for removal or recovery
by
compaction comprising:
providing a generally cylindrical compression barrel having a discharge
5 opening at one end of the compression barrel, a lead end opposite the
discharge
end and a peripheral wall;
feeding the biomass material into a feed inlet opening in the peripheral
wall of the compression barrel;
rotating an auger shaft within the compression barrel acts to carry the
biomass materials from the feed inlet opening to the discharge end and to
apply
pressure to the biomass material as it is discharged through the discharge
end;
the auger shaft driving the biomass material from the compression
barrel into the forming barrel mounted at the discharge end of the compression
barrel ;
the forming barrel having a peripheral wall at least a part of which is
formed from a series of parallel longitudinally extending bars defining slots
therebetween with the bars being supported to hold them against outward
movement under the pressure from the compressed biomass material;
the biomass material containing a liquid content between 10 % and
50%;
CA 02639275 2008-09-03
6
and generating sufficient heat and pressure in the forming barrel to
cause at least part of the liquid content to be discharged through said at
least a part
of the peripheral wall.
Preferably the pressure generated in the forming chamber is at least
1000 psi and is more preferably of the order of 20,000psi.
Preferably the density of the compressed biomass material discharged
from the forming barrel is of the order of 50lbs/cu ft.
The arrangement therefore provides a biomass compactor using an
auger to compress the biomass material such as straw, sawdust, or flax waste
which
can contain high levels of liquid up to 50%. The compactor has a slotted
section
formed by the bars closing around the materials path through the machine such
that
moisture released from the material under the high temperature and pressure
generated by the auger can be released through the slots. This way, the
machine
uses the same mechanical process to both compact and dry out the biomass
material, thereby reducing or eliminating the need to dry the biomass material
in a
separate prior process.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
Figure 1 is a schematic side elevational view of a biomass compactor
according to the present invention.
Figure 2 is a schematic top plan view of the biomass compactor of
I '
CA 02639275 2008-09-03
7
Figure 1.
Figure 3 is an end elevational view of the forming barrel taken along
the lines 3-3 of the biomass compactor of Figure 1.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
DETAILED DESCRIPTION
In Figures 1 and 2 is shown generally the biomass compactor which
includes a primary cylinder or barrel 10 which acts as a compression barrel
within
which the biomass material is compressed by an auger 11 within the barrel 10.
The
barrel 10 has an inlet 12 in one side. Barrel 12 has a cylindrical peripheral
wall 13, a
first closed end 14 and a second open end 15 through which the compressed
materials are discharged.
The auger 11 comprises a series of independent flights so that each
flight has a start position and an end position where the ends of the flights
are
spaced longitudinally along the auger shaft. This forms a multi-start auger
system in
which the material entering the barrel can engage into the position between
the
individual flights to be carried by the flights during their movement caused
by rotation
of the auger shaft 15. The auger shaft 15 is formed from a sleeve 16 and an
inner
shaft 17 on which the sleeve 16 is mounted. The shaft 17 is carried in
bearings 18
and 19 and is driven by a motor 20 communicating drive to an input pulley 21.
Thus
the shaft extends co-axially with the cylinder 10 and the sleeve 16 is carried
on the
outside surface of the shaft 17 so that the sleeve and the shaft project into
the
i . ... . . . ,. . .. . .. . . . . . i
CA 02639275 2008-09-03
8
interior of the barrel and axially along the barrel 10 to the discharge end
15. The
auger flights are mounted on the outside of the sleeve 16 and extend from the
outside surface of the sleeve 16 to the cylindrical inside surface of the
barrel 10.
This provides a spacing between the outside surface of the sleeve and the
inside
surface of the barrel 10 which is of the order of 2 inches in height.
Typically the
sleeve has an outside diameter of the order of 4 inches so that the inside of
the
barrel has a diameter of the order of 8 inches. These dimensions are of course
only
typical and other dimensions can be used particularly when the structure is
scaled
upwardly to larger dimensions for transporting and compressing larger
quantities of
material.
The inlet 12 of the barrel 10 is supplied by a feed system generally
indicated at 25 which includes a tube 26 which is fed from a hopper 27. The
tube 26
extends horizontally away from one side of the barrel 10 and the hopper 27 is
mounted on an outer end of the tube so as to provide feed material to be fed
into the
tube and along the tube into the inlet 12. The hopper 27 is generally
rectangular
with side walls 28 and 29 and end walls 30 and 31 with the end walls at right
angles
to the tube 26. At the bottom, the hopper converges inwardly to a base 33
centrally
of the side walls 28 and 29 and generally aligned with the tube 26. An auger
34 is
mounted at the base so that the materials failing to the base and converge
inwardly
to the base are carried along the base and into the tube 26 by the auger 34
and the
flights thereon. The auger 34 is driven by a motor 35 through a drive chain 36
at the
end 30 of the hopper. The auger 34 is mounted in bearings 37 and 38 at the end
CA 02639275 2008-09-03
9
walls 30 and 31 and extends up to the entrance into the barrel 10 so as to
compress
the materials from the hopper and feed the materials into the auger flights to
ensure
a smooth continuous flow of the material into the auger flights on the shaft
15.
As many of the materials to be supplied into the barrel 10 for
compression are fibrous, bridging is typically a problem within the hopper so
that
rotating members 40 and 41 are provided within the hopper above the auger 34
and
on opposite sides of the auger 34. The rotating members 40 and 41 comprise
shafts
42 carried in bearings 43 and driven by a motor 44 through a chain drive
system 55.
The rotary members 42 carry fingers or blades 56 projecting outwardly from the
bars
42 for engaging into the material.
Typically the auger 34 rotates at an angular rate which is variable to
control an input speed whereas the rotating members 40 and 41 which are not
intended to carry out any driving action rotate at a slow rate at the order of
5 to 10
RPM.
The auger 11 carried on the shaft 15 carries, as previously explained,
a plurality of auger flights. In the embodiments shown there are four such
auger
flights indicated at 11A, 11 B, 11 C and 11 D. Each of these auger flights
extends to
an end 11 E at the discharge from the barrel 10. Each of these auger flights
has
attached thereto a tip portion 11 F at or adjacent the end 11 E. This tip
portion is
formed of a wear resistant material such as carbide. As shown in Figure 2, the
ends
11 E and the tip portions 11 F project into a forming barrel 45 so that they
project
beyond an end wall 46 of the barrel 10 and thus provide a short portion which
is
CA 02639275 2008-09-03
proud of the end wal146 and projects into the interior of the forming barrel
45.
Each of the tips 11 F has a leading end 11 G and a trailing end 11 H.
The tips are mounted on the auger flights so that the leading ends 11G all lie
substantially in a common plane radial to the axis of the shaft 15. Thus the
leading
5 edges of the tips in the clockwise direction of rotation of the auger 11 as
shown in
Figure 3 lie in a first plane radial to the axis of the shaft and the trailing
edges 11 H all
lie in a second plane at radial of the axis. The second plane radial of the
axis of the
edges 11 H is arranged to be axially advanced further into the forming barrel
than the
leading edges. In this way the tips form wiping blades which wipe over the
material
10 sitting in the barrel 45 so as to push against the rear surface of that
material in a
wiping action to smooth the material and to apply compressive force against
the
material to force the material along the barrel 45.
Thus as the auger 11 rotates, each flight carries material forwardly and
discharges it into the barrel 45. That material as it is discharged is then
wiped and
smoothed by the action of the tips. This arrangement has been found to provide
an
effective action in compressing and squeezing the materials to apply high
compressive forces which also significantly increase the temperature within
the
material at this location.
The effect of the multi-start auger together with the tips can apply a
pressure up to 20,000 psi within the material at the entrance to the forming
barrel 45.
At the same time the temperature is typically elevated to a temperature of the
order
of 400 F. This high compression and high temperature acts to evaporate liquids
and
CA 02639275 2008-09-03
11
moisture within the material so that the gases so formed are driven off from
the
material.
As best shown in Figure 3, the barrel 10 has a circular opening 10A at
the discharge end which emerges into the barrel 45. The barrel 45 is of
increased
transverse dimension so that a space is formed between the imaginary cylinder
defined by the outside edge of the opening 10A and the inside surface 45B of
the
barrel 45. Thus the material which is fed forwardly by the auger 11 on the
shaft 15
emerges through the annular space around the shaft 15 and inside the opening
10A
of the barrel 10 and that material is forced axially as well as outwardly into
the space
inside of the wall of the barrel 45. The area beyond the end of the shaft 15
is filled
by a shaft extension portion 15A which is coaxial with the shaft 15 and of the
same
diameter and extends into the barrel 45 along its full length. The extension
portion
15A is stationary and has an end 15B butting against the end of the shaft 15
at the
end of the auger at the location just inside the barrel 45.
The previously explained wiping action carried out by the tips 11 F acts
to apply pressure onto the material forcing it into a generally cylindrical
area beyond
the annular space and outwardly of the annular space to fill the whole of the
interior
of the barrel 45 outside the extension portion 15A.
This generates a compressed mass which is generally cylindrical with
an inner surface defined by the outer surface of the cylindrical extension
portion
15A.
Thus the mass formed in the compression is cylindrical with a distance
CA 02639275 2008-09-03
12
D from the inside surface to the wall of the barrel 45 which is of the order
of 2.0
inches. In this way the distance of any point in the compressed mass to the
slotted
wall of the barrel is relatively small and generally less than 3.0 inches so
that gases
and vapour and liquid can readily escape under compression.
The barrel 45 is polygonal in shape formed by wall portions 45A. In
the example shown the barrel is octagonal with the wall portions of equal
width.
However other shapes can be used including square barrels and irregular shaped
polygonal barrels.
The wall portions 45A are each defined by a series of parallel
longitudinally extending bars 47 which lie in a common plane of the wall
portion 46.
The bars are supplied with a support system which holds the bars at a pre
determined spacing which is typically of the order of 0.030 inch. The bars are
triangular in shape with a flat face facing inwardly and an apex facing
outwardly to
provide sufficient strength for the bar while allowing a narrow slot at the
face of the
wall which faces inwardly.
Such structures are commonly available and are widely used in the oil
industry under the trade name "Wedge-Wire". Such materials are supplied with
the
ability to withstand significant outward forces while maintaining the narrow
gap
between each bar and the next bar. The bars extend along the full length of
the
chamber 45 from the end wall 46 through to a discharge end 50 of the forming
chamber. The bars are supported by peripheral ribs 51 which are located at
spaced
positions along the length of the bar. Each rib 51 forms a peripheral flange
I
CA 02639275 2008-09-03
13
extending around the full periphery of the barrel 45 so as to provide a fully
surrounding band which prevents the significant forces within the barrel 45
from
bowing the bars 47 outwardly.
The ribs 51 are continuous around the bars 47 so that outward
stresses from the bars are communicated into tension in the ribs. An inside
edge of
the ribs engages the outside tip of the bars 47 to hold the tips against
outward
movement. The ribs can are welded at spaced positions along the bars.
The ribs are formed from sheet metal with the inside edge in contact
with the bars and an outside edge spaced outwardly therefrom. In this way the
ribs
interfere with the exit of gases and liquid to the minimum extent.
Around the forming barrel 45 is provided a collection chamber 57
which is formed from a peripheral wall 58 and end walls 59 which contain the
whole
of the forming barrel such that the gases and liquid escaping are contained
within
the outside container 57 and can drain to a discharge opening 60 for
collection. A
vacuum can be applied at the discharge 60 to draw off the gases so that they
can
discharge safely or can be collected if valuable. In this way oils and other
valuables
excreted from the compressed materials can be collected for processing and
sale.
In this way the environment within the area surrounding the device can be kept
free
from contaminants exiting from the forming barrel.
An end plate 62 is provided on the end of the forming barrel and
provides an orifice 63 through which the materials are discharged. The end
plate 62
can be adjusted so as to change the dimensions of the orifice so that the
plate
. .. . . . . ,. . . . . . . ............ . . i.
CA 02639275 2008-09-03
14
provides a back pressure on the materials being forced through the forming
barrel.
This is particularly desirable at start-up in order to commence the
application of back
pressure through the forming barrel and into the compression barrel. Once the
back
pressure is developed, the friction between the materials and the wall of the
forming
barrel maintain that back pressure at a required level so as to generate the
required
pressures within the material.
Typically the shaft can be driven at a rate in the range 50 to 400 RPM
depending on size. This rate can of course be varied within this range to
control the
pressures within the system. Other parameters can be varied to control the
conditions within the system.
Typically the machine can be controlled so as to generate pressures in
the range 1000 TO 20,000 psi and temperatures in the range 250 to 450 degrees
F.
Control of the system is primarily managed by measuring the temperature by a
suitable sensor at the main compaction area at the tips of the auger and by
measuring pressure within the compaction zone obtained by maintaining a
resultant
density in the range 50 to 65 lbs/cu ft.
In order to provide a sufficient throughput of material, the space
between the extension portion 15A and the wall of forming barrel 45 is
generally of
the order of 2 to 3 inches in transverse dimension. However this total area of
the
cylindrical shape is too great in most cases to form an acceptable product
which can
be used in subsequent combustion processes. In order to manufacture combustion
products of a desired transverse dimension, divider walls 66 are provided
within the
. . .. . .. ... . ... .. . . ... .. . . .. i .. ..... . .. . . _. . . . ..-...
. . ..... .- ._,.<. ...._.; . .... .. .
CA 02639275 2008-09-03
forming barrel which divides the total area into smaller separate areas with
the
materials being separated at a leading edge 68 of the dividing walls. This
leading
edge is located immediately downstream of the trailing edge 11 H of the tips
of the
auger. The dividing walls are formed of sheet metal so as to reduce friction
and
5 allow the compressed materials to slide along the surfaces of the dividing
walls and
along the surfaces of the bars 47.
In Figure 1 is shown an additional component 70 which is mounted
beyond the exit gate 62 defined by the plate and this component forms a long
tube
through which the materials emerge so as to provide a cooling action. The
structure
10 can be formed of aluminium to ensure the extraction of significant
quantities of heat
so that the emerging compressed materials are sufficiently cooled for
handling.
As an alternative, the forming barrel defined by the bars 47 can be
removed from the end wall of the compression barrel and replaced by a simple
tubular forming member defined by the component 70. The forming barrel 45 can
be
15 removed and replaced by a forming barrel defined by the component 70 in the
event
that the materials are sufficiently dry and free from oil to remove the
necessity for
extraction of such materials through the bars 47. However the forming barrel
used
has basically the same arrangements and characteristics as that previously
described except that it is formed from the same tubular structure. Thus it
cooperates with the tips of the auger as previously described and thus it
includes
dividing walls as previously described. In this case the forming barrel
defined by the
component 70 is longer since it carries out both the functions of forming and
of
. .. .. . .. . .. . .. i .. . . .. . . ... .. .......... . .
CA 02639275 2008-09-03
16
cooling.
The apparatus uses primarily stainless steel components due to the
high acid content of many of the biomass feed stock materials it can be used
to de-
water.
Animal wastes, oil seed plant wastes and other biomass feed stock
with moisture contents up to 50% can be reduced to solids exhibiting very low
moisture content. In order to achieve this, the pressure within the entrance
to the
forming barrel is typically of the order of 20,000PS1. The resulted solids are
appropriate for burning in a down draft gasifier or other conventional
combustion
system and typically such systems require a density of the compressed product
of
the order of 50 lbs. per cubic foot.
As shown the construction uses four auger flights and therefore
includes four tips. However this may be reduced to three or increased as
required.
The use of multiple tips in this manner permits faster throughput while
minimizing
side thrust. As the flights are spaced around the axis, this spreads the side
to side
forces generated by the forwarding of the material around the axis.
The auger produces a hollow cylindrical compacted shape permitting
liquid to leave the biomass compressed product at a very high rate. This
produces a
large volume of dewater material with reduced energy costs. Liquid, air and
steam
in the feedstock will migrate the short distance from the outside edge of the
auger at
the tips 11 F and from the outside of the extension portion 1 5A to the slots
between
the bars where it is released. It will be appreciated that the significant
point of
CA 02639275 2008-09-03
17
compression and heating occurs at the tips of the auger flights where the
material is
pushed into and applied onto existing material within the forming barrel. At
this
location, therefore, the maximum heating action occurs as the compression
effect is
maximized.
Typical materials which can be processed include animal waste
including poultry, cow and hog manure and even including sewage waste from
households. The liquid extracted can be used as fertilizer. The solids
material in the
compacted shapes can be used as a combustion fuel.
The temperature of compression which generally reaches of the order
of 400 degrees F acts to sterilize pathogens.
Other materials can be processed including various plant products.
One process includes growing hemp and similar plants on contaminated land
which
act to draw out the contaminants, following which the plant material is
compressed in
the system described above to extract oil while the contaminants remain in the
compacted solids and can be extracted by combustion while using the heat
generated. Such contaminants can include various metals which can be extracted
and valuable metals collected.
Another process involves waste paper where the compaction can be
used to extract the liquid content including ink, the compacted solids formed
into a
fuel product which is used in a combustion system and remaining clay from the
paper being collected in the ash. Thus all of the components of the waste
paper are
either recovered or used to generate heat as a fuel.
,
CA 02639275 2008-09-03
18
These processes are enabled by the high level of liquid content which
is allowed in the system and by the efficient use of energy to drive the
system to
effect the compaction.
Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments of same made
within the spirit and scope of the claims without department from such spirit
and
scope, it is intended that all matter contained in the accompanying
specification shall
be interpreted as illustrative only and not in a limiting sense.
