Note: Descriptions are shown in the official language in which they were submitted.
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FUEL LOG OF RECYCLED MATERIALS AND METHOD FOR MANUFACTURE
This invention relates to fuel logs and other fuel elements made of
organic fibrous materials mixed with a combustible oil. The term "log" is
intended
herein to include both bodies shaped and arranged for burning in a fire place
or
stove and bodies shaped for burning in other locations such as industrial
heating
systems and power station where coal has been a primary heat source.
This application relates to the subject matter disclosed in Canadian
application 2,639,275 filed September 3, 2008, entitled BIOMASS PRESSURE
LIQUID RECOVERY SYSTEM to which reference may be made for further detail.
BACKGROUND OF THE INVENTION
Manufactured fire logs are normally used as substitutes for cordwood
in fireplace and small wood stoves during power outages for example or simply
for
pleasure. Synthetic fire logs can be purchased one at the time and are
generally
wrapped neatly, making them more attractive than natural wood blocks to the
occasional user. Their clean-burning characteristics are advantageous over
natural
wood, and therefore these logs are also preferred by the environment-conscious
people.
Also in a related field, power stations are commonly fueled by coal and
it is highly desirable to replace this fuel source with a renewable energy
source from
recycled materials to avoid depletion of fossil fuels and to avoid the
contaminants
commonly present in coal.
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Fire logs currently available to consumers are dividable in two types.
The first type contains about 40 - 60% wax with the remaining portion being
sawdust, wood chips or wood shavings. The second type contains wood fibers in
various forms impregnated with vegetable, animal or petroleum oil. In both
types, the
wax and the oil are the primary source of heat with the fibrous material being
the
substratum of the product. Typically, fire logs have a heat capacity of almost
twice
as much as cordwood and their moisture contents are much lower, providing a
more
complete combustion.
US Patent 1,484,302 issued to C. Y. Garrett on Feb. 19, 1924,
discloses a combustible block which is used as a fire kindling material. The
block is
made of pieces of wood, or wood pulp impregnated with resin and coated with
wax.
Different compositions are proposed. For example, the wood shavings content is
25% to 75% and the resin content is 25% to 58%.
US Patent 4,120,666 issued to S. R. Lange on October 17, 1978,
discloses an artificial fireplace log made of shredded paper and wax. The
preferred
proportions are 32% to 45% paper and 55% to 68% wax.
US Patent 4,326,854 issued to J. D. Tanner on April 27, 1982
discloses a synthetic fire log made of 35%-40% by weight of cellulosic
material such
as wood or paper, a suitable liquid combustible by-product such as vegetable
or
animal oil, and a gelling agent to solidify the liquid by- product therein.
US Patent 5,244,472 issued to J. J. Simmons on Sept. 14, 1993
discloses a method to manufacture cellulosic fuel from wood chips impregnated
with
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vegetable oil. The wood chips are immersed in hot vegetable oil and heated to
reduce the moisture content in the wood chips to less than 10 %, and until the
oil
content of the wood chips is between 10% to about 30%.
US Patent 6,017,373 issued to G. Frisch on Jan. 25, 2000 discloses an
artificial log which contains coriander seeds to create a crackling sound. The
log is
made of 35% to 55% by weight of a combustible material such as wood chips,
sawdust, cardboard, and 45% to 65% by weight of a flammable wax binder
material
such as paraffin or stearic acids derived from vegetables.
US Patent 6,458,177 issued to M. Cox on October I, 2002, discloses a
synthetic fire logs made of wood waste and wax in a ratio of 40:60.
Emissions from residential wood stoves, furnaces and fireplaces
contribute significantly to particulate matters (PM) and volatile organic
compounds
(VOC) released in the air. The adverse effects of these and other pollutants
on
human health and on the environment is well known.
The type of synthetic fire logs which is of interest herein contains
primarily fibrous organic materials, and vegetable oil as the primary fuel
element. It
is known that vegetable oil is more combustible than wood resins and - wax,
and
therefore the oil burns more efficiently with less pollution than natural wood
or
paraffin wax. Therefore, it is believed that air polluting emissions,
including
particulate matters, carbon oxides, benzene, an formaldehyde, can be reduced
significantly by burning manufactured fire logs containing vegetable oil,
instead of
cordwood or synthetic logs containing petroleum oils or paraffin wax.
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PCT Published Patent Application 2005/010132 published February 3
2005 by Bonnell-Rickard et al discloses an arrangement intended to infuse as
much
vegetable oil as possible in cellulosic material from recycled paper to make
synthetic
fire fogs. Vegetable oils and especially used cooking oils are easily
available from
restaurants and hotels for examples, and therefore this product is a preferred
ingredient for making synthetic fire logs. The composition of the fire log
comprises
recyclable organic fibers from recycled paper over-saturated with vegetable
cooking
oil. The vegetable oil is infused into the organic fibers and is contained and
sealed
therein by an envelope made of the vegetable wax. The proportion of vegetable
oil
is 65% - 75% by weight. The vegetable oil is used vegetable cooking oil. The
organic
fibrous substratum thereof represents about between 20%-30% by weight and
consists of compressed paper-based products such as cardboard, newsprint, and
other recyclable paper. A vegetable wax envelope is provided which represents
about between 1-5% of the weight of the log.
This is obtained by compressing cellulosic pulp by about 1/3 of its
initial volume to expel water to provide a water content of roughly 15%. The
log so
formed is then heated to dry it to a water content of about 1 %. The heating
takes of
course a high energy use so that the economics of the process are highly
questionable.
This arrangement contains a very high proportion of oil which therefore
requires to be contained by a wax coating. The use of paper as a primary
source is
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unsuitable as it contains clay as a binder which leads to a high quantity of
ash and
also contains undesirable toxins.
5 SUMMARY OF THE INVENTION
It is one object of the present invention to provide a combustible solid
which has a high calorific value.
According to the present invention there is provided a fuel source
comprising:
a base formed of a cellulosic or fibrous organic material which is
compressed to a density of at least 50 lbs/cu ft;
a combustible oil absorbed into the base material such that the content
of oil is less than 50% by weight;
the base material being arranged such that the content of ash when
the source has been fully combusted is less than 10% by weight.
Preferably the oil content is less than 35%.
Preferably the density of the base material lies in the range 50 to 85
lbs/cu ft.
Preferably the oil is a vegetable oil.
Preferably the ash content is less than 2%.
Preferably the quantity of oil is arranged such that the amount of oil is
substantially the maximum which can be absorbed while the oil has no tendency
to
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escape from the base material.
Preferably the base material containing the oil is dry to the touch.
Preferably the base material has an exterior surface which is
substantially free from an exterior coating.
Preferably the base material contains a quantity of fibers from recycled
paper which relatively low so as to avoid the presence of toxins generally
present in
paper.
Preferably the base material is compressed to a moisture content of
less than 15%.
Preferably the base material has a calorific value of greater than 4,000
BTU/Ib and preferably greater than or of the order of 5,000 BTU/lb and
generally in
the range 4000 to 10,000.
According to a second aspect of the present invention there is provided
method for forming a combustible solid fuel source comprising:
providing a base formed of a cellulosic or fibrous organic material;
compressing the base material to a density of at least 50 lbs/cu ft;
the compression being arranged to reduce the moisture content of the
base material to less than 15%;
and contacting the base material with a combustible oil so as to cause
the oil to be absorbed into the base material such that the content of oil is
less than
50% by weight.
Preferably the base material after compression is contacted by the oil
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substantially without the addition of heat to the base material.
Preferably the base material has a moisture content prior to
compression of at least 25%.
19. The method according to claim 11 wherein moisture and oil are
expelled from the base material during the compression.
The arrangement therefore described hereinafter provides a fuel
source formed from any cellulose or fibrous organic based product that has
been
mechanically processed or compressed, such as in a press or screw compression
mechanical device, that has been supplemented with a higher BTU organic oil.
The
oil may be processed or not. The resulting BTU content is significantly higher
than
the host material. This can include but is not limited to agricultural and
biomass
waste or surplus products such as flax seed oil, canola oil, or biodiesel or
hydrocarbons or coal oil extracts or any manner or higher BTU content fuels
added.
The fuel material defined by the source can be in the form of a log for
use in a home or similar situation. Such a log may have a diameter or
transverse
dimension roughly in the range 4 to 6 inches and may have a length selected
according to the end use since the logs can be cut to a required length.
Typically a
home use log will be of the order of 12 to 24 inches. Longer lengths can be
used to
assist in transportation for example where the log length is 7.5 feet to allow
the logs
to be stacked lengthwise across a typical transportation container of 8 feet.
Where the intention is to feed an existing furnace such as a coal fired
furnace or a power station, the logs may be ground up to any required shape
and
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size to feed the known systems. The grinding action may generate smaller
pieces
for feeding using the conventional feeding conveyor systems or may reduce the
logs
to a powder for air flow feeding or fluidized bed technology. The formation of
log
shape, that is a continuous body of constant dimension, is particularly
suitable using
available compression systems for example of the type described herein.
However
other compression systems forming other shapes may be used.
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 layout of a system for manufacturing a solid
fuel source according to the present invention.
Figure 2 is a schematic side elevational view of a biomass compactor
for use in the method of Figure 1.
Figure 3 is a schematic top plan view of the biomass compactor of
Figure 2.
Figure 4 is an end elevational view of the forming barrel taken along
the lines 4-4 of the biomass compactor of Figure 1.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
DETAILED DESCRIPTION
In Figure 1 is shown a method for forming a combustible solid fuel
source in the form of logs, briquettes and pellets and the like. The method
includes
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supplying a biomass supply 100 which provides a base material of a fibrous or
cellulosic material.
Any fibrous or vegetable material can be used and examples of such
materials include wood waste and sawdust from the lumber industry, any waste
vegetable material from agriculture such as wheat straw and chaff, corn cobs,
rice
husks, and animal waste such as horse or cow manure, and hog waste. The supply
may form part of a larger processing system which takes the waste and removes
liquid for re-use and compresses the remaining solids to form the compressed
base
materials. Thus the supply can be taken from animal plants such as hog plants
where the manure is currently a problem and is processed to provide fuel.
Horse
manure is particularly suitable as it contains much fibrous material which
remains
undigested and thus is generally of large volume and low water content.
Wood products which are high in oil content can be used such as
cedar and palm in that the oil can be initially extracted by the compression
system
described herein and then oil can be re-absorbed after the compression is
removed.
The same or a different oil can be absorbed. Typically the cedar oil is
unsuitable in
that it contains contaminants which are unsuitable to be burnt in the end
product.
Thus the system can be used to clean up palm waste which is typically
difficult to use because of its high oil content.
The biomass material is taken from the supply and passed through a
compression system 101 for compressing the base material. The compression
system can be of the type described in detail hereinafter. However a simple
press
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system can be used of a conventional nature. The compression however must be
relatively high so that screw type systems are preferred since these can
generate
the high pressures and high temperatures required to expel excess moisture and
to
increase the density to required levels.
5 The screw system described hereinafter allows compression of the
biomass materials described to a density of at least 50 lbs/cu ft and
generally in the
range 50 to 65 lbs/cu ft. Thus for example a fibrous mass containing 25% water
content at a density of the order of 16lbs/cu ft can be compressed to a mass
at a
density of at least 50 lbs/cu ft and as much as 85 lbs/cu ft and a moisture
content of
10 less than 2%. Thus the compression system 101 includes a water expulsion
system
102 as a part of the compression system. Typically no heat is added for a
drying
action as this requires additional energy costs. However some initial
separation of
water and solid material may occur using a mechanical separation system to
reduce
initial moisture content to a lower initial value.
A combustible oil is provided in a supply 104 which may be passed
through a treatment system 105 to remove contaminants or to add additives such
as
scenting materials. Contaminants from cooking oil can be removed where the
supply is a used cooking oil using techniques which are well known.
The compressed solid material from the compression system 101 is
contacted with the oil in a mixer 106. This can be a simple mixing bath where
the
solid compressed bodies are passed through the bath on a conveyor or are
merely
dumped into the bath and removed by a lifting system.
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This causes the oil to be absorbed into the base material such that the
content of oil is less than 50% by weight, les than 35% and generally of the
order of
30%. This level of absorption is achieved typically by the bodies sitting in
the bath
partly immersed in the oil. For example the logs may be carried on a screen
type
conveyor into a bath of the oil such that approximately one half of the log is
immersed leaving an upper half exposed. The process can be controlled by
changing the rate of forwarding movement of the conveyor so that the log is
half
immersed for a period of time such that the oil can be observed to wick up to
the top
of the log. When this has occurred, a sufficient quantity of oil has been
absorbed
allowing the conveyor to carry the log out of the bath where it can be blown
dry of
any sitting oil by an air stream and then can be allowed to sit and drain any
excess
from the surface. The oil which has been absorbed by the wicking action of the
fibers remains contained and does not leak no matter how long the log is
allowed to
sit. No covering of wax or other encapsulating material is required. Although
a
wrapping of paper or other material may be provided for presentation to the
public.
It will be appreciated that the compression process described hereinafter
causes
initial compression under high load thus reducing the volume to a maximum
extent
while the compression remains in effect. At this stage substantially no air
spaces
remain. However when the compression is removed the body will slightly expand
allowing the fibers to move slightly apart so that the oil can enter into the
spaces
thus formed between the fibers and is actively drawn into these spaces by the
expansion effect.
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No heating for drying of the compressed base materials is required
although the oil may be warmed to aid absorption. The compression of the
material
to the above stated levels allows the oil to be taken up to a percentage by
weight
typically of the order of 30% without any additional step to increase take up.
Leaving
the material in the bath for a longer time typically does not increase take
up. The oil
is absorbed through the whole body of the material so that it is take up to a
common
level throughout the structure.
The oil is a preferably a vegetable oil as it is a renewable resource but
in some cases other oils such as coal oil or petroleum based oils can be used.
Although these are less suitable in view of the content of contaminants unless
the
contaminants are removed in a preliminary process.
After the oil is absorbed, the material including the oil is removed from
the bath and placed in a location 107 to drain off any surface oil for
collection and
return to the bath. After draining for a period sufficient to allow any
surface oil to fall
off, the quantity of oil is arranged within the material such that the oil has
no
tendency to escape from the base material. That is the oil remains captured
within
the structure for an extended period and such that the base material
containing the
oil is dry to the touch.
The drained base material containing the oil is then moved to a
packaging system 108 where it can be wrapped in a suitable covering such as
wax
paper. The material itself therefore has an exterior surface which is wholly
or at
least substantially free from an exterior coating such as wax since the oil
remains
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encapsulated without such a coating. The wrapping material is used simply for
packaging of logs for home use so that they are suitable presented to the home
user. In a situation where the material in briquette or pellet form is to be
used in
bulk for example in a furnace, no wrapping is required. Bulk transport systems
can
be used as are well known to persons skilled in this art.
One example of a compression system which can achieve the above
conditions for the base material is shown in Figures 2, 3 and 4, where
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 coaxially 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
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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 falling 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
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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
5 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
10 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.
15 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 11 A, 11 B, 1 1C 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 3, 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
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proud of the end wall 46 and projects into the interior of the forming barrel
45.
Each of the tips 11F has a leading end 11G and a trailing end 11H.
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
edges of the tips in the clockwise direction of rotation of the auger 11 as
shown in
Figure 4 lie in a first plane radial to the axis of the shaft and the trailing
edges 11H 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
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
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moisture within the material so that the gases so formed are driven off from
the
material.
As best shown in Figure 4, the barrel 10 has a circular opening 1OA 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 1
OA
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
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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
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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
discharged 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
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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
5 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
10 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
15 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
20 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
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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
allow the compressed materials to slide along the surfaces of the dividing
walls and
along the surfaces of the bars 47.
In Figure 2 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
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
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 co-
operates 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
CA 02675494 2009-08-12
22
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 20,000PSI. 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 15A to the slots
between
the bars where it is released. It will be appreciated that the significant
point of
CA 02675494 2009-08-12
23
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 02675494 2009-08-12
24
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.
