Note: Descriptions are shown in the official language in which they were submitted.
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Title: Fuel pellet containing recycled cellulosic material and method of
making
the fuel pellet.
BACKGROUND
(a) Field
[0001] The subject matter disclosed generally relates to fuel pellets
containing cellulosic materials. More specifically, the subject matter
disclosed
generally relates to fuel pellets containing recycled waxed and non-waxed
cellulosic material and a method of manufacturing a fuel pellet.
(b) Related Prior Art
[0002] Fuel pellets of different compositions of materials have been
used for heating since the mid-nineteen eighties. Typically, the fuel pellets
are
burned in a stoker stove, and are associated with residential style heating
systems. Due to increased environmental awareness and a demand for new
sources of energy, an alternative fuel source can be created by recycling
waste products. Since 1984, when the first pellet-burning stove was
introduced by Pyro Industries, there has been an increased interest in
creating a pellet fuel comprised of waste paper, waste cardboard and
agricultural residues.
[0003] Several fuel pellets comprised of cellulosic materials have been
patented. For example, U.S. Pat. No. 4,236,897 to Johnston discloses a fuel
pellet comprised of natural cellulosic material and synthetic polymeric
thermoplastic material. Johnston further discloses using binding agents in the
composition of the fuel pellet in addition to thermoplastic materials, such as
paraffin slack wax and carnauba wax.
[0004] U.S. Pat. No. 5,342,418 to Jesse discloses a method of making
a fuel pellet comprised of cellulosic material. The fuel pellet described
therein
is comprised of 60 to 90 percent by weight of cellulosic material, and 10 to
40
percent by weight of a thermoplastic resin. The fuel pellet disclosed by Jesse
purposefully produces an ash output of at least 1 percent by weight, so as to
protect the equipment which carries the fuel into the furnace.
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[0005] While each of the above described fuel pellet compositions and
methods of making the fuel pellets function adequately, they each have the
drawback of requiring the addition of a binder material to bind the cellulosic
particles together. Fuel pellets have been manufactured without the presence
of binder material, but they require that the cellulosic particles be highly
compressed together in order to increase the temperature of the particles and
activate the natural lignin present therein, which will act as a natural
binder
material. Fuel pellets manufactured with a binder material can be
manufactured at much lower pressures since it is not necessary to melt the
lignin, as the binder material will bind the cellulosic particles together.
Therefore, there is a need for a fuel pellet composition that does not require
the addition of a binder material, and that can be manufactured at lower
pressures.
SUMMARY
[0006] In a first embodiment there is disclosed a fuel pellet which
contains about 25% to about 75% by weight of cellulosic material, and about
14% to about 75% by weight of waxed cellulosic material.
[0007] The fuel pellet may contain about 20% to about 45% by weight
of manure, cereal, or a mixture of both manure and cereal.
[0008] The fuel pellet may contain about 20% to about 45% vegetal oil.
[0009] The cellulosic material of the fuel pellet may be chosen from
cardboard, card stock, carton, corrugated fiberboard, paperboard, paper, and
newspaper.
[0010] The cellulosic material of the fuel pellet may be vegetable fibre
chosen from cotton, bamboo fibre, esparto, papaya, coir, sisal, kapok, jute,
ramie, flax, roselle hemp, hemp, kenaf, abaca, soybean fibre, okra fibre, vine
fibre, babana fibre, rattan and nettles.
[0011] The cellulosic material of the fuel pellet may be a biomass
chosen from sawdust, wood shavings, bagasse, fruit pit, fruit core, vegetable
pit, vegetable core, maize leaf, straw and grass and switchgrass.
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[0012] The waxed cellulosic material of the fuel pellet may be chosen
from wax coated cardboard, wax coated card stock, wax coated carton and
wax coated paper, wax coated corrugated fiberboard, wax coated
paperboard.
[0013] The manure contained in the fuel pellet may have a density of
about 650 g/L to about 700 g/L.
[0014] The cereal contained in the fuel pellet may be chosen from
maize, rice, wheat, barley, sorghum, millets, oats, rye, tricale, buckwheat,
finio, quinoa, and spelt.
[0015] The cereal contained in the fuel pellet may be chosen from a
whole grain, a endocarp of a grain, a germ of a grain, a bran of a grain, a
powder from a whole grain, a powder from a endocarp of a grain, a powder
from a germ of a grain, and a powder from a bran of a grain.
[0016] When grain is present in the fuel pellet, the fuel pellet may
contain a liquid, and the liquid may be water or potato juice.
[0017] The vegetal lipid present in the fuel pellet may be chosen from
linseed oil, tung oil, castor oil canola oil, sunflower oil, safflower oil,
peanut oil,
olive oil, almond oil, hydrogenated oil, and shortening.
[0018] The fuel pellet may contain 42.9% by weight of cellulosic
material, 14.3% by weight of waxed cellulosic material, and 42.9% by weight
of manure, cereal, or a mixture of both manure and cereal.
[0019] The fuel pellet may have a humidity content from about 6% to
about 17%, and the fuel pellet may have a heat output from about 6000 BTU
per pound to about 15000 BTU per pound.
[0020] In a second embodiment, there is disclosed a method of
manufacturing a fuel pellet which comprises crushing and mixing the materials
of the fuel pellet having about 25% to about 75% by weight of cellulosic
material, about 14% to about 75% by weight of waxed cellulosic material, and
a liquid, measuring a humidity content of the materials of the fuel pellet,
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adjusting the humidity content of the materials of the fuel pellet; and
forming
the fuel pellet.
[0021] The method of manufacturing the fuel pellet may also comprise
about 20% to about 45% by weight of manure, cereal, or a mixture of both
manure and cereal. It may also comprise about 20% to about 45% vegetal oil.
[0022] The method of manufacturing the fuel pellet may also comprise
humidity content from about 6% to about 17%. When the humidity content is
above about 17%, the method further comprises an addition of cellulosic
material, and further mixing the materials of the fuel pellet. When the
humidity
content is below about 6%, the method further comprises an addition of a
liquid and manure, or both, and further mixing of the materials of the fuel
pellet. The liquid may be chosen from water and potato juice.
[0023] The method of manufacturing the fuel pellet may also comprise
reserving the materials of the fuel pellet after crushing and mixing.
[0024] The fuel pellets manufactured by the method of manufacturing
the fuel pellet may have a heat output from about 6000 BTU per pound to
about 15000 BTU per pound.
[0025] The following terms are defined below.
[0026] The term "cellulosic material" is intended to mean material that
contains lignocellulose, which is composed mainly of cellulose, hemicellulose
and lignin. Lignocellulose is the structural material that comprises much of
the
mass of plants, which is used to make pulp for the fabrication of paper,
cardboard and other products from wood.
[0027] The term "waxed cellulosic material" is intended to mean
material that contains lignocellulose, onto which a coating of wax has been
added.
[0028] The term "manure" is intended to mean organic matter used as
organic fertilizer in agriculture and which contribute to the fertility of the
soil by
adding organic matter and nutrients to the soil.
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[0029] The term "grain" is intended to mean the edible components of
the fruit seeds of cereals grasses, such as wheat, maize and barley. The
grains that can be used in the present invention do not need to be comestible.
[0030] The term "vegetal lipid" is intended to mean lipid materials (fats
and oils) derived from plant material. The vegetal lipid that can be used in
the
present invention do not need to be comestible.
[0031] Features and advantages of the subject matter hereof will
become more apparent in light of the following detailed description of
selected
embodiments, as illustrated in the accompanying figures. As will be realized,
the subject matter disclosed and claimed is capable of modifications in
various respects, all without departing from the scope of the claims.
Accordingly, the drawings and the description are to be regarded as
illustrative in nature, and not as restrictive and the full scope of the
subject
matter is set forth in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Fig. 1 is a block diagram of the process of making the pellet of
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] In embodiments there are disclosed a fuel pellet which contains
about 25% to about 75% by weight of cellulosic material, about 14% to about
75% by weight of waxed cellulosic material.
[0034] In another embodiment there are disclosed a fuel pellet which
contains about 25% to about 75% by weight of cellulosic material, about 14%
to about 75% by weight of waxed cellulosic material; and about 20% to about
45% by weight of manure, grain, or a mixture of both manure and grain.
[0035] In another embodiment there is disclosed a method of
manufacturing a fuel pellet by crushing and mixing the materials of the fuel
pellet having from about 25% to about 75% by weight of cellulosic material,
from about 14% to about 75% by weight of waxed cellulosic material.
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[0036] In another embodiment there is disclosed a method of
manufacturing a fuel pellet by crushing and mixing the materials of the fuel
pellet having from about 25% to about 75% by weight of cellulosic material,
from about 14% to about 75% by weight of waxed cellulosic material, and
from about 20% to about 45% by weight of manure, grain, or a mixture of both
manure and grain; measuring a humidity content of the materials of the fuel
pellet, adjusting the humidity content of the materials of the fuel pellet;
and
forming the fuel pellet.
[0037] The fuel pellet
[0038] This invention provides an improved fuel pellet of naturally
occurring combustible material, including at least 50% cellulosic material and
a process of its manufacture. The pellet has excellent combustion
characteristics.
[0039] The fuel pellet of the present invention may be formed in any
shape desired. The fuel pellet of the present invention may also be formed in
any size desired.
[0040] An example of a fuel pellet of the present invention is comprised
of a plurality of layers and partial layers stacked one upon another, and
extending in a direction generally transverse to the longitudinal axis of the
pellet. The layers generally comprise components of the materials from which
the pellets are made, and they are typically rather thin, and packed tightly
together in the pellet. A transverse surface of the pellet (e.g. either ends,
or a
new surface made by breaking the pellet along a transverse direction)
typically comprises a plurality of partial layers folded, mixed, and otherwise
randomly entwined and entangled with each other in both the axial and
transverse directions. The flexible nature of the cellulosic material used
within
the composition of the pellets may also result in some cellulosic material
being packed and extend along the axial length of the pellet. However, the
pellets do contain some layers which comprise a single layer element
extending across the entire transverse dimensional area of the pellet.
Furthermore, some materials used in the fabrication of the pellets will retain
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their granular character (e.g. grains) and will be incorporated within the
layered stacks of the pellets and will extend across the length of several
layers of the cellulosic material used in the pellet.
[0041] The pellet of the present invention is made from a selected
composition of recycled, waste, as well as agricultural residual by-products
as
raw materials. Preferred raw materials are clean or soiled recycled waxed and
non-waxed cellulosic materials which are obtained from post-consumer
recuperation operations. Another preferred source of raw material is waste
waxed and non-waxed cellulosic materials which are obtained from garbage
collection operations. The preferred agricultural residual by-products may be
obtained from farming operations and comprise useful and non-useful by-
products from the harvest, animal by-products, and by-products obtained from
clearing of agricultural fields. The raw material composition comprises a
mixture of recycled, waste and agricultural residual by-products materials, so
long as the required ingredients are present in amounts within the specified
ranges. The raw material suitable for use in this invention may be secured in
the form of sheets, films, bulk fibre, or the like, or is readily converted to
one
or more of those forms. The raw agricultural by-products material may be
secured in the form of comestible and/or non-comestible plant material, and/or
animal manure.
[0042] The composition of raw material suitable for use herein
generally comprises a first fibre component which comprises about 25% to
about 75% by weight, and preferably about 28 to 43% by weight, based on
dry weight. The first component of cellulosic material may be comprised of a
dense cellulosic fibre stock such as cardboard, card stock, carton, corrugated
fiberboard, paperboard, paper, news paper and other heavy duty, as well as
other conventional paper used in writing, printing or packaging activities.
[0043] The first component of cellulosic material may also be vegetable
fibre obtained from fibre crops grown for their fibre for use in fabrication
of
paper, cloth or rope, for example. The fibre may be bast (skin) fibre
collected
from the bast surrounding the stem of plants (or tree) such as jute, roselle
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hemp, hemp, ramie, flax, kenaf, rattan, soybean, okra, vine, and banana. The
vegetable fibre may also be from cotton, bamboo fibre, esparto, papaya, coir,
sisal, kapok, abaca and nettles. Biomass may also be the source of the first
component of the cellulosic material. Typical source of biomass may be
sawdust, wood shavings, and grass, such as any of the panicum species of
grasses (e.g. panicum amarun, panicum anceps, panicum antidotale,
panicum decompositum (native millet), panicum miliare (little millet), panicum
virgatum (switchgrass) or panicum grus-galli) and the like. Residues from
harvest such as maize leaf, and straw, residues from agricultural extraction
processes such as bagasse, fruit or vegetable pits and cores may also be
sources of biomass.
[0044] The balance of the cellulosic element is a second component
which comprises about 25% to about 75% by weight, and preferably about 14
to 43% by weight of a waxed cellulosic fibre, based on dry weight. The second
cellulosic component comprises a waxed cellulosic material of dense
cellulosic fibre stock such as cardboard, card stock, carton, corrugated
fibreboard, paperboard, paper, and other heavy duty, as well as other
conventional paper used in writing, printing or packaging activities.
Especially
desirable dense cellulosic fibre stocks are, for example, wax coated single
layer cardboard or three ply corrugated board, and about 90 lb. to about 180
lb. carton stock, coated with wax, polyethylene, or the like. Fuel pellets are
not
manufactured only from the second cellulosic component of waxed cellulosic
fibre because of the high efficiency of combustion of this material. Burning
of
pellets made only from waxed cellulosic residues cause the furnace in which
they are burnt to crack and break because of the very high temperature they
are able to generate.
[0045] The fuel pellet of the present invention does not require the
addition of any thermoplastic resins other than the wax present on the second
cellulosic component. Such waxes are commonly added to other types of fuel
pellets to act as a bonding agent. The waxes present on the waxed cellulosic
material used in the present invention acts as bonding agents to assist in
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bonding the layers together to make the pellets. They allow the use of lower
pressures during the fabrication of the pellets, since it is not necessary to
use
high pressures to melt the natural lignin present in cellulosic materials to
bind
them together. They are preferred for their lubrication properties and their
ability to soften and flow at low temperatures to assist in the bonding
together
of the pellets during pellet fabrication.
[0046] The fuel pellet composition may be completed by the addition
agricultural residues in the form of animal by-products such as manure, the
addition of cereals, in a proportion from about 20% to about 45% by weight, in
combination with a sufficient quantity of liquid, or both manure and cereals.
[0047] The manure is typically in solid (farmyard) or slurry (liquid) form,
and contains feces mixed with urine. Farmyard type manures will contain an
amount of plant material, preferably straw, which was used as bedding for the
animals and has absorbed the feces and urine. Manure may be from different
animal origin including horse, cattle, pig, sheep, chicken, turkey, rabbit,
and
human. Animal manures may also contain other animal products such as wool
shoddy, feathers, blood and bone. The manure used in the present invention
preferably has a density of about 650 to about 700 g/L of manure.
[0048] Cereals may also be added to the composition of the fuel pellet
of the present invention. The cereal may be used alone or in combination with
manure. When used alone, a sufficient quantity of liquid, in the form of water
or potato juice is added to the mixture before mixing of the components.
Cereals that can be used in the present invention include cereal grains from
maize, rice, wheat, barley, sorghum, millets, oats, rye, tricale, buckwheat,
finio, quinoa, and spelt. The cereals used in the fuel pellets of the present
invention may be comestible or non-comestible. The cereals used in the fuel
pellets of the present invention may be from a whole grain, a endocarp of a
grain, a germ of a grain, a bran of a grain, a powder from a whole grain, a
powder from a endocarp of a grain, a powder from a germ of a grain, and a
powder from a bran of a grain.
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[0049] Vegetal lipids may also be added to the composition of the fuel
pellet of the present invention, in a proportion from about 20% to about 45%
by weight. The vegetal lipids may be fats, oils, or a mixture of both fats and
oils. They are composed of triglycerides, and may be edible or inedible.
Examples of inedible vegetable fats and oils include processed linseed oil,
tung oil, and castor oil used in lubricants, paints, cosmetics,
pharmaceuticals,
and other industrial purposes. Examples of edible fats and oils are canola,
sunflower, safflower, peanut and olive, almond oils. Although thought of as
esters of glycerin and a varying blend of fatty acids, fats and oils also
typically
contain free fatty acids, monoglycerides, and diglycerides.
[0050] Fuel pellets having the above compositions produce heat of
combustion in the range of about 6000 to about 15000 BTU/Ib., which is
generally acceptable for having a heat of combustion of about 12500 to about
13000 BTU/Ib. Preferred heat of combustion is about 9000 to about 12000
BTU/Ib., with a target range of about 9500 to about 11500 BTU/Ib. Fuel pellets
having the above composition generally have an ash output of approximately
1% to 5%.
[0051] Method of making the pellets
[0052] Now referring to Figure 1, for manufacture of the fuel pellets of
the present invention, the raw materials, as described and defined above, are
preferably fed into a shredder (crusher, or granulator), which does the
initial
size reduction, and from there into a hammer mill or other size reducing
apparatus (e.g. a pulveriser), where the raw material is further reduced to
the
desired size. The preferred size of the particle is about 0.25 inches. The
hammer mill or pulveriser has a size controlling exit screen which controls
the
size of the exiting milled material. The details of the shredder and
pulveriser
(or hammer mill) structure and operation are not shown as these are well
known in the pelletizing art.
[0053] Next, the shredded materials are mixed to uniformly distribute
the humidity within the mixture. The humidity content is tested to be about 6%
to about 17%, and preferably 15.5%. Moisture content of the mixture of
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materials is important to produce fuel pellets of a high quality, to prevent
the
mixture of the materials of the composition to be too pasty and, importantly,
to
prevent burning of the materials inside the pelleting apparatus because of the
high heat generated during the pelletizing step. To adjust a humidity content
that is too low, a suitable quantity of liquid co ntaining material or liquid,
preferably water or potato juice is added to the composition. Dry cellulosic
material (waxed and/or unwaxed) is added to the composition to adjust the
humidity content if it is too high. Optionally, the mixed materials may then
be
transferred to a reserve bed before they are introduced into the pelletizing
apparatus.
[0054] The mixed materials from the hammer mill/pulveriser are fed to
a pelletizing apparatus. The pelletizing apparatus is generally conventional
in
design. The details of the pelletizing apparatus structure and operation are
not
shown as these are well known in the pelletizing art. The pelletizing
apparatus
may optionally have a conditioning unit, but its use during the pelletizing
step
of the fuel pellet of the present invention is not necessary.
[0055] The friction created within the pelletizing apparatus generates
heat which softens the wax in the waxed cellulosic material, and causes some
softening and hydrogen bonding of the cellulose fibres in the presence of the
available water. Especially the softened wax serves as a lubricant to
facilitate
movement of the material through the apparatus. Small amounts of moisture
are also present, and will assist in the lubrication function. The frictional
resistance in the pelletizing apparatus, results in the raw material being
tightly
packed in a random arrangement of layers and partial layers extending
generally transverse to the longitudinal axis, and thus transverse to the
length
of the pellet being formed. The tight packing produces the friction which
produces heat. While additional heat may be applied (e.g. resistance heaters
in the apparatus) usually, the heat produced by the friction in the apparatus
is
sufficient for satisfactory operation of the pelletizing apparatus.
[0056] As the formed pellets are extruded from the pelletizing
apparatus, they tend to break off due to weight of the extrudate, the
vibration
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of the mill, or they are cut by a knife adapted to cut them at a predetermined
length, or the like, and fall down onto a conveyor or a receiving bin. The
fuel
pellets are transported to a screen over which the pellets are passed to
remove fines. The pelletized product which does not pass through the screen
is then transported, for example, by conveyor to the finished product
container.
Alternative embodiments
[0057] EXAMPLE I
[0058] An exemplary fuel pellet composition is prepared by mixing the
following components:
Cellulosic material Waxed cellulosic material Manure
Wax coated cardboard
Cardboard (42.86%) (14.28%) Horse manure (42.86%)
[0059] The cellulosic material (cardboard, 300 pounds), waxed
cellulosic material (waxed cardboard, 100 pounds), and manure (horse
manure, 300 pounds, 700 g/L density). The materials were crushed, shredded
and mixed, the humidity content was adjusted to 15.5%, and fuel pellets were
prepared in a pelletizing apparatus.
(0060] EXAMPLE II
[0061] An exemplary fuel pellet composition is prepared by mixing the
following components:
Cellulosic material Waxed cellulosic material Grain
Wax coated cardboard
Cardboard (42.86%) (14.28%) Wheat (42.86%)
[0062] The cellulosic material (cardboard, 300 pounds), waxed
cellulosic material (waxed cardboard, 100 pounds), and grains (wheat, 300
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pounds, in water). The materials were crushed, shredded and mixed, the
humidity content was adjusted to 15.5%, and fuel pellets were prepared in a
pelletizing apparatus.
[0063] The embodiments and examples presented herein are
illustrative of the general nature of the subject matter claimed and are not
limiting. It will be understood by those skilled in the art how these
embodiments can be readily modified and/or, adapted for various applications
and in various ways without departing from the spirit and scope of the subject
matter disclosed claimed. The claims hereof are to be understood to include
without limitation all alternative embodiments and equivalents of the, subject
matter hereof. Phrases, words and terms employed herein are illustrative and
are not limiting. It will be appreciated that any aspects of the different
embodiments disclosed herein may be combined in a range of possible
alternative embodiments, and alternative combinations of features, all of
which varied combinations of features are to be understood to form a part of
the subject matter claimed.
