U.S. patent application number 10/900530 was filed with the patent office on 2006-02-02 for environmentally friendly fire logs.
Invention is credited to William E. Sonnier.
Application Number | 20060021276 10/900530 |
Document ID | / |
Family ID | 35730559 |
Filed Date | 2006-02-02 |
United States Patent
Application |
20060021276 |
Kind Code |
A1 |
Sonnier; William E. |
February 2, 2006 |
Environmentally friendly fire logs
Abstract
A fire log composition is provided that includes a combustible
material(s), a modified plant oil(s) and a wax(es). A continuous
process for the manufacture of a fire log is also provided. A fire
log composition is provided that includes a combustible material, a
plant oil and a wax.
Inventors: |
Sonnier; William E.;
(Pasadena, TX) |
Correspondence
Address: |
BAKER BOTTS L.L.P.;PATENT DEPARTMENT
98 SAN JACINTO BLVD., SUITE 1500
AUSTIN
TX
78701-4039
US
|
Family ID: |
35730559 |
Appl. No.: |
10/900530 |
Filed: |
July 28, 2004 |
Current U.S.
Class: |
44/535 |
Current CPC
Class: |
C10L 5/365 20130101;
C10L 5/44 20130101; Y02E 50/10 20130101; Y02E 50/30 20130101 |
Class at
Publication: |
044/535 |
International
Class: |
C10L 11/00 20060101
C10L011/00 |
Claims
1. A fire log composition comprising: a combustible material; a
modified plant oil; and a wax.
2. The fire log composition of claim 1 wherein the combustible
material comprises wood or vegetable fibers.
3. The fire log composition of claim 1 wherein the plant oil
comprises tall oil pitch residue.
4. The fire log composition of claim 3 wherein the tall oil pitch
residue is saponified, neutralized, distilled, and acidulated.
5. The fire log composition of claim 1 wherein the wax comprises
polyethylene wax.
6. The fire log composition of claim 1 comprising about 50% by
weight combustible material.
7. The fire log composition of claim 1 wherein the ratio of plant
oil to wax is about 19:1.
8. The fire log composition of claim 1 wherein the ratio of plant
oil to wax is about 4:1.
9. The fire log composition of claim 1 wherein the ratio of plant
oil to wax is about 1:1.
10. The fire log composition of claim 1 wherein the ratio of plant
oil to wax comprises about 1:19 to about 19:1.
11. The fire log composition of claim 1 comprising about 35% to
about 65% by weight combustible material.
12. The fire log composition of claim 1 further comprising at least
one compound selected from the group consisting of esters and
olefins.
13. The fire log composition of claim 1 wherein the wax comprises
polypropylene wax.
14. The fire log composition of claim 1 wherein the wax comprises
alpha olefin wax and polyethylene wax.
15. The fire log composition of claim 1 wherein the combustible
material comprises at least one material selected from the group
consisting of sawdust, wood flour, vegetable fibers, vegetable
flour, and/or mixtures thereof.
16. The fire log composition of claim 1 wherein the wax comprises
at least one compound selected from the group consisting of
polyethylene wax, polypropylene wax, vegetable oil esters, olefins,
alpha olefins and/or mixtures thereof.
17. The fire log composition of claim 1 wherein the plant oil
comprises modified tall oil pitch residue and the wax comprises
polyethylene wax.
18. The fire log composition of claim 17 further comprising at
least one other wax.
19. A fire log composition comprising: a combustible material; a
tall oil compound selected from the group consisting of modified
tall oil, modified tall oil pitch, modified tall oil pitch residue,
modified tall oil soap and/or mixtures thereof; and a wax.
20. The fire log composition of claim 19 wherein the wax comprises
polyethylene wax.
21. The fire log composition of claim 19 wherein the compound is
modified tall oil pitch residue, said pitch residue having been
saponified, neutralized, distilled, and acidulated.
22. The fire log composition of claim 19 wherein the log is
comprised of about 50% by weight combustible material.
23. The fire log composition of claim 19 wherein the ratio of tall
oil compound to wax is about 19:1.
24. The fire log composition of claim 19 wherein the ratio of tall
oil compound to wax is about 4:1.
25. The fire log composition of claim 19 wherein the wax comprises
alpha olefin wax and polyethylene wax.
26. The fire log composition of claim 25 wherein the ratio of tall
oil compound to alpha olefin wax to polyethylene wax is about
80:10:10.
27. A fire log composition comprising: at least one material
selected from the group consisting of wood fibers, vegetable
fibers, wood flours, vegetable flours and/or mixtures thereof; at
least one first compound selected from the group consisting of
modified tall oil pitch, modified tall oil, modified tall oil
residue, modified tall oil pitch residue, modified tall oil soap,
and/or mixtures thereof; and at least one second compound selected
from the group consisting of polyethylene wax, polypropylene wax,
vegetable oil esters, olefins, alpha olefins and/or mixtures
thereof.
28. The fire log composition of claim 27 comprising about 50% by
weight of the at least one material.
29. The fire log composition of claim 27 comprising up to about 95%
first compound.
30. The fire log composition of claim 27 comprising wood fibers or
flour, modified tall oil pitch residue, and polyethylene wax.
31. A continuous process for the production of manufactured fire
logs, said process comprising: heating a wax and an oil, blending
the wax with the oil to form an oil/wax blend; providing a
combustible material; mixing the combustible material and the
oil/wax blend to form a mixture; cooling the mixture; optionally,
further mixing the cooled mixture; extruding the mixture to form an
extrudate for the production of individual fire logs.
32. A process according to claim 31, wherein the oil/wax blend is
at a temperature of about 250 degrees to about 350 degrees F.
33. A process according to claim 31, wherein the temperature is
about 170 degrees F. to about 250 degrees F. during the initial
mixing of the oil/wax blend and the combustible material.
34. A process according to 31, wherein the oil/wax blend and
combustible material mixture is cooled to a temperature of about 70
degrees F. to about 130 degrees F.
35. A process according to claim 31, wherein the temperature of the
extrudate is about 70 degrees F. to about 130 degrees F.
36. A process according to claim 31, wherein the extruding step is
through a die such that the extrudate has a certain shape with
either square or "V" shaped grooves formed thereon.
37. A process according to claim 31, wherein the oil component
comprises saponified, neutralized, distilled, and acidulated tall
oil pitch residue.
38. A process according to claim 31, wherein the wax component
comprises polyethylene wax.
39. A process according to claim 31, wherein the combustible
material comprises wood fiber.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates generally to novel
manufactured fire log technology. More particularly, the present
invention relates to novel manufactured fire log compositions
comprising renewable materials, and novel continuous processes for
manufacturing the same.
BACKGROUND OF THE INVENTION
[0002] Fire logs have been used for many years as a source of heat
in homes, etc. Fire logs are not only desired for the warmth they
provide, but they also create a desirable cozy atmosphere. A
traditional fire wood log consists of a section cut from a tree.
Traditional wood logs have numerous disadvantages including but not
limited to problems in relation to storage, use, emissions and
disposal. For example, traditional wood logs typically are messy.
The logs often leave chips of wood and bark behind. Because the
logs are untidy, the logs are usually stored outside the home.
Storing logs outside the home creates another disadvantage to the
user, namely, the user may need to go outside to get the logs on a
cold and/or inclement day. Bringing outside logs inside may create
the additional disadvantage of introducing insects/pests, e.g.,
ants and termites into the home. Also, tradition firewood is
typically very high in moisture content, particularly when stored
outside or when it has been recently cut, i.e., "green". This adds
to the difficulty in lighting and burning the logs. As a result,
the user is sometimes frustrated. Often, in an attempt to light the
log, dangerous situations may arise, from using flammable
chemicals, gasoline, or using paper products that create a
dangerous situation for the user. Once lit, the traditional fire
wood log needs to be monitored and frequently replaced with fresh
logs to keep the fire stoked. Because traditional fire wood log
fires burn at a relatively low temperature, they generate a
considerable amount of undesirable emissions in the form of smoke,
particulate matter and toxic chemicals such as carbon monoxide and
cresols which can harm the environment and cause damage to the
fireplace and flue. And when the fire is extinguished, traditional
wood logs leave behind a considerable quantity of ash that has to
be removed.
[0003] Heretofore known manufactured logs have solved some of the
historical problems caused by the burning of traditional fire wood.
Manufactured logs are neatly packaged for storage in the home, are
typically easier to ignite, typically burn longer, produce
significantly less emissions as compared to traditional fire logs,
burn for a known duration, and produce much less ash than
traditional fire wood.
[0004] Nearly all commercially available manufactured logs are
composed of various types of fuel bodies formed with combustible
materials that are compressed into a cylindrical or rectangular
shape. For example, Yates (U.S. Pat. No. 4,179,269) discloses a log
that includes ground coal. Schrader (U.S. Pat. No. 4,333,738)
reports a log containing coal liquid and paraffin wax. Tutupalli et
al. (U.S. Pat. No. 6,136,054) disclose a log that includes
cardboard and wax. These manufactured logs have inherent
environmental disadvantages, e.g., they include polluting
components. For example, coal and wax products may burn
incompletely, potentially discharging volatile chemicals into the
atmosphere. This results in the added disadvantage of depositing
volatile combustion products in the fireplace flue. These volatile
build-ups may ignite later with disastrous results. Because of the
seriousness of this problem, insurance companies today recommend
alternating use of manufactured logs with traditional fire wood
logs.
[0005] Current manufactured logs have focused on incorporating
certain common waste materials into fire logs. For example,
numerous waste materials have been suggested for use in modern
manufactured logs, e.g., but not limited to sawdust, wood fiber,
dried coffee grounds (U.S. Pat. No. 6,113,662), rice hulls or
shredded paper (U.S. Pat. No. 3,297,419), ground bark and peanut
shells (U.S. Pat. No. 4,040,796), grass clippings with chipped and
ground branches and twigs (U.S. Pat. No. 5,393,310), and cardboard
boxes (U.S. Pat. No. 6,136,054). The environmental benefits of
these logs come from using waste materials, and therefore
freeing-up landfill space. However, these solutions do not
necessarily contribute to a cleaner burning log or hotter burning
log that produces fewer emissions.
[0006] Therefore, a need exists for a manufactured log that not
only utilizes common waste but renewable materials that also
produces fewer emissions than traditional firewood and some
manufactured logs as well.
SUMMARY OF THE INVENTION
[0007] The present invention is directed, according to one
embodiment, to compositions comprising a combustible material or
combustible materials and a blend, preferably a high melt point
blend, comprising a modified renewable oil, preferably a plant oil,
and a wax-based material(s) or a polymer(s). The preferred
compositions of the present invention comprise about 50%
combustible material(s) by weight of the total composition. The
combustible material(s), according to one embodiment of the present
invention, comprises a wood-based material, preferably comprising
sawdust and/or wood flour. The blend, according to one embodiment,
preferably comprises a renewable plant oil and preferably,
substantially comprises a modified tall oil component. The modified
tall oil is, according to an embodiment, comprised substantially of
modified tall oil pitch, e.g., but not limited to tall oil pitch
residue that has been saponified, neutralized, distilled, and
acidulated. Note, the applicant has discovered that the sole use of
an oxidized tall oil component like oxidized tall oil pitch
residue, as opposed to the use of a predominantly modified tall oil
component, is not desired in the practice of the present invention.
While, not meant to be limited hereby, applicant believes the
modified tall oil component of the present invention is
advantageous over a previously oxidized tall oil component because
the modified component appears to be lower in viscosity and
molecular weight and thus, more readily absorbed into the
combustible materials, e.g., wood fibers. A log manufactured from a
tall oil component consisting substantially of an oxidized tall oil
component has been found to quite often drip during burning
indicating undesired free oxidized tall oil/wax blend on the
surface of the fibers making it unsatisfactory for consumer use. A
modified tall oil component of the present invention does not
suffer from this undesired burning defect.
[0008] The wax preferably, according to one embodiment, comprises
polyethylene wax. According to one embodiment of the present
invention, the composition preferably comprises a ratio of oil to
wax of 80:20. However, it being understood, that based upon the
particular oil and/or wax combination utilized other ratios may be
used in the practice of the present invention, e.g., ratios of oil
to wax may include 50:50, 60:40, 75:25, 85:15, 90:10 etc.
[0009] According to one embodiment, the present invention comprises
a combustible material, a modified tall oil component and a
wax.
[0010] According to another embodiment of the present invention,
the composition comprises at least one material selected from the
group consisting of vegetable or plant flour, sawdust, wood flour
or mixtures thereof; at least one modified tall oil component
compound selected from the group consisting of tall oil pitch, tall
oil pitch residue, crude tall oil, tall oil soap, and mixtures
thereof; and at least one compound selected from the group
consisting of polyethylene wax, polypropylene wax, vegetable oil
esters, olefins, alpha olefins and/or mixtures thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A more complete understanding of the present embodiments and
advantages of the embodiments of the invention may be acquired by
referring to the following description taken in conjunction with
the accompanying drawings, in which like reference numbers indicate
like features, and wherein:
[0012] FIG. 1A illustrates a log configuration according to one
aspect of the present invention;
[0013] FIG. 1B illustrates a log configuration according to one
aspect of the present invention;
[0014] FIG. 2 illustrates an example of a process of the present
invention; and
[0015] FIGS. 3 and 4 illustrate examples of extrusion dies that may
be used in the practice of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT
INVENTION
[0016] The present invention is directed to fire log compositions
comprising a combustible material or materials and a blend of a
modified plant oil(s) and wax(es), preferably, a high melt point
blend of the same and methods of manufacture.
[0017] The combustible materials may include any flammable
substances. For example, a combustible material could, for example,
be any substance of cellulosic origin such as wood or vegetable
fibers. According to one embodiment of the present invention, the
combustible material is sawdust. Sawdust may include any roughly or
finely ground wood-based particulate matter. If sawdust is finely
ground, it is then commonly referred to as wood flour. Examples of
combustible materials include particulates having size diameters
ranging from about 5 millimeters, for example sawdust, to about
0.15 millimeters, for example wood or vegetable flour. Some
embodiments of the present invention comprise combustible materials
comprising pine and mesquite tree sawdust and/or flour, but other
embodiments may encompass other hard and soft woods as well.
[0018] In another embodiment of the present invention, the
combustible material(s) is(are) dried before adding the same to the
mixture or composition. Often, recently produced sawdust is
"green." If it contains high moisture content, it can be dried by
placing in a heated environment such as an oven or a commercial
dryer for a set period of time. Drying the sawdust improves the
combustion nature of the sawdust by increasing the average Btu
value and also improves the sawdust's ability to absorb the blend
of liquid components, e.g., the oil and wax components, of the
compositions, which in turn results in a mechanically stronger
manufactured fire log with superior burn characteristics.
[0019] Other embodiments of the present include combustible
materials that are a mixture of one or more different types of
sawdust and/or wood flour as described above. For example,
combustible materials may comprise a mixture of sawdust and wood
flour.
[0020] According to one embodiment of the present invention, a fire
log composition comprises about 50% by weight combustible material.
The compositions of the present invention may comprise from about
35% to about 65% by weight combustible material(s) of the total
fire log composition.
[0021] Other embodiments of the present invention may comprise a
log with different ranges of combustible material(s). For example,
one inventive log may comprise from about 35% to about 40% by
weight combustible material of the total composition. One
embodiment of the present invention may comprise from about 40% to
about 45% by weight combustible material of the total composition
weight. Another embodiment of the present invention may comprise
from about 45% to about 50% by weight combustible material of the
total weight of the composition. Other embodiments of the present
invention may comprise from about 50% to about 55% by weight
combustible material(s) of the total composition weight. Yet
another embodiment of the present invention may include a log
comprising from about 55% to about 65% by weight combustible
material of the total composition weight.
[0022] An embodiment of the present invention relates to fire log
compositions that include modified plant oil/oils. The plant oil(s)
may be any combustible extract from a plant. The modified plant oil
preferably comprises, e.g., a saponified, neutralized, distilled,
and acidulated plant oil component.
[0023] In one embodiment of the present invention, the modified
plant oil comprises tall oil that is typically derived from tall
oil soap. Tall oil is the resinous material found in trees that
includes fatty acids, rosin acids, sterols and alcohols. During the
digestion phase of the wood pulping process, tall oil soap is
formed on the top layer of the solution. The tall oil soap is
skimmed from the digester. Typically, sulfuric acid is used to
reduce the pH (a process commonly known as acidulation). This
process allows for the separation of the tall oil soap from the
water (tall oil soap is typically about 50% water). In one
embodiment of the present invention, the modified tall oil compound
component may comprise tall oil fatty acids, rosin acids, tall oil
heads, crude tall oil, tall oil residue, tall oil pitch, tall oil
pitch residue, and mixtures thereof. Preferably, in the practice of
one embodiment of the present invention, a modified tall oil pitch
residue derived from tall oil pitch is utilized. Preferably, the
tall oil pitch of this embodiment is modified via saponification,
neutralization, distillation, and acidulation.
[0024] The most preferred oil component, e.g., the modified tall
oil pitch residue of one embodiment of the present invention is
available from Chusei (U.S.A.) Inc., 12500 Bay Area Blvd.,
Pasadena, Tex. 77507. The most preferred modified tall oil pitch
residue useful in the practice of an embodiment of the present
invention comprises a mixture of long chain and tricyclic organic
acids, sterols, and fatty acids (and may include, e.g., about 0-2%
phosphoric acid) and has the following physical characteristics:
boiling point ->280 C; softening point--approximately 40 C;
specific gravity (water=1)--approximately 0.98; solubility
(water)--NIL (@ 25 C); pH about 5.5 to about 7.0; vapor density
(air=1)>1; physical state--liquid above 60 C; appearance &
odor--dark solid, tar-like odor; flash point (COC)>250 F; acid
value <40.
[0025] Using a modified tall oil component, especially a modified
tall oil pitch residue, has, in accordance with one embodiment of
the present invention, numerous environmental benefits. First, tall
oil is a byproduct of the wood pulping process and readily
available. Tall oil is a low value byproduct typically in over
supply and it is often difficult to find appropriate uses for the
material. A second environmental advantage of manufactured fire
logs using a tall oil component, in accordance with the practice of
one embodiment of the present invention, is that fewer emissions
are produced compared to traditional fire wood. Due to the fact
that the oil and fiber components of the present invention are
derived from plants, e.g., trees, the primary components are
renewable resources and thus, preferred over the use of other
manufactured fire logs not employing as significant a proportion of
renewable resources.
[0026] An embodiment of the present invention relates to a fire log
composition that comprises a wax or waxes. The wax may comprise any
low or high melting organic mixture or compound of high molecular
weight. The wax may be derived from natural or synthetic sources.
Natural sources may comprise waxes from animals, insects,
vegetables, and mineral or petroleum sources. Synthetic sources
may, e.g., comprise waxes created from petrochemical processes. The
wax may comprise any isotactic, syndiotactic or atactic structures
or mixtures thereof.
[0027] In one embodiment of the present invention, the wax
component predominantly comprises a polyethylene wax. The
polyethylene wax may comprise, e.g., high density polyethylene wax,
low density polyethylene wax and/or mixtures thereof. In a
particular embodiment of the present invention, the wax may
comprise an oxidized wax, e.g., an oxidized polyethylene wax.
[0028] In another embodiment of the present invention, the wax
component may predominantly comprises polypropylene wax. The
polypropylene wax may comprise, e.g., high density polypropylene
wax, low density polypropylene wax and/or mixtures thereof. In a
particular embodiment, the wax is predominantly an atactic
polypropylene wax.
[0029] Other embodiments of the present invention may comprise an
ester or an olefin-based wax. In a particular embodiment, the wax
component may comprise an alpha-olefin wax and a polyethylene wax.
In a further embodiment, the ratio of oil, e.g., plant oil, to wax,
e.g., an alpha olefin wax to polyethylene wax is about 90:9.5:0.5.
In a preferred embodiment of the invention, the ratio of oil, e.g.,
plant oil, to wax, e.g., an alpha olefin wax, to polyethylene or
polypropylene wax is about 80:10:10. In another embodiment of the
present inventive composition, the fire log composition may
comprise at least two or more waxes.
[0030] In relation to one embodiment of the present invention, the
plant oil may comprise up to 80% by weight of the oil and wax blend
by weight. Other embodiments of the present invention, may comprise
mixtures of wax and modified plant oil ranging from about 30% to
about 70% by weight of the log by weight.
[0031] According to one embodiment of the present invention, the
wax is mixed with the modified plant oil in various ratios. In one
embodiment, the ratio of plant oil to wax is about 19:1. In another
embodiment, the ratio of modified plant oil to wax is about 4:1.
The ratio of modified plant oil to wax may also be roughly equal to
about 1:1. In other embodiments of the present invention, the ratio
of modified plant oil to wax comprises from about 11:9 to about
19:1, however other ratios may be utilized depending upon the
combustible material(s) (e.g., sawdust, flour, and mixtures) used
and the state of the oil component, i.e., whether it is saponified,
neutralized, distilled, and/or acidulated. Further, other ratios
may be utilized depending on the wax utilized in relation to the
specific modified plant oil component utilized.
[0032] The wax and modified plant oil, according to one embodiment
of the present invention, may be combined to form a molten liquid
blend. In one embodiment, the modified plant oil may comprise up to
about 95% of the total blend by weight. In another embodiment, the
plant oil may comprise up to about 80% of the blend by weight. In
one embodiment, the blend comprises about 65% plant oil by weight.
In another embodiment, the plant oil may comprise up to about 70%
of the blend by weight. However, the amount of modified plant oil
utilized man be varied depending upon the other components utilized
to manufacture the fire log in accordance with various embodiments
of the present invention.
[0033] According to a preferred embodiment of the present
invention, a blend may comprise up to about 80% plant oil by weight
of blend. Other embodiments include blends comprising plant oils by
weight in the following: up to about 55% to about 60%, up to about
60% to about 65%, up to about 65% to about 70%, up to about 70% to
about 75%, up to about 75% to about 80%, up to about 80% to about
85%, up to about 85% to about 90%.
[0034] One embodiment of the present invention comprises fire log
compositions that further comprise an ester (or esters) or an
olefin (or olefins). Esters may include acetates and carbonates
such as vegetable oil esters and tall oil esters. Olefins, also
referred to as alkenes, may include, e.g., any unsaturated,
aliphatic hydrocarbons having one or more double bonds. In one
embodiment of the present invention, the olefin component includes
alpha olefins. Alpha olefins, while not meant to be limited
thereby, generally tend to be considered more reactive than other
olefins because of the location of the double bond.
[0035] Another embodiment of the present invention comprises fire
log compositions comprising at least one compound selected from the
group consisting of polyethylene wax, polypropylene wax, vegetable
oil esters, olefins, alpha olefins and mixtures thereof. In a
further embodiment, the inventive fire log compositions of the
present invention may also comprise at least one modified compound
selected from the group consisting of tall oil, crude tall oil,
tall oil pitch, tall oil pitch residue, tall oil soap, and
mixtures/combinations thereof.
[0036] Logs may be produced by the following process. Generally, a
fire log composition is made by mixing the combustible material(s),
plant oil(s) and wax(es), preferably at an elevated temperature,
e.g., the temperature should typically be at least 20 F higher than
the melting point of the highest melting component of the mixture
Preferably, according to one embodiment, about 70 to about 100 F
higher for efficient mixing. Next, the mixture is cooled (referred
to herein as "pasta") and then extruded.
[0037] The pasta is preferably produced using, e.g., a continuous,
high intensity mixer and the continuous mixture is controlled at an
elevated temperature (typically between about 175.degree. F. and
about 230.degree. F.) while the combustible material(s), and the
heated oil(s)/wax(es) blend are fed into the mixer on a continuous
and controlled basis. The combustible material(s) is(are)
preferably relatively dry, e.g., at least 80% dry (which is
believed to assist in the absorption of the oil/wax mixture). In
other embodiments, the combustible material(s) may be 95% dry.
Preferably, the combustible material(s) is(are) below 12% moisture
and most preferably below 8% moisture. Note, in relation to overall
moisture of the composition, if the oil/wax blend component is not
of sufficient weight, i.e., the composition is too dry, a later
formed log may crack or swell upon extrusion and may undesirably
break into several pieces.
[0038] The plant oil(s) need to be pre-treated before mixing with
the wax(es), i.e., the tall oil component is modified. It is has
been found that modifying the tall oil effects certain physical
properties such as melt point and in viscosity. This has proven
advantageous in the ability to continuously process the logs.
Adjusting the melt point and the viscosity help allow for the
production of a log that does not fall apart when being extruded
and packaged or when being handled, stored and burned by the
consumer.
[0039] The plant oil(s) and wax(s) are pre-mixed before added to
the combustible material(s). Maintaining the wax and plant oil
mixture under elevated temperature is necessary to produce a
homogeneous liquid mixture prior to adding to the combustible
material(s). Because it is desirable that the final log be hard at
ambient temperature, it has been found advantageous to use a wax
and tall oil mixture with physical properties that provide for a
hard and durable fire log at ambient temperature. In one
embodiment, the plant oil and wax are mixed together under elevated
temperature to form a liquid mixture that quickly hardens at
ambient temperature.
[0040] The combustible material(s) is(are) then mixed with the
liquid. It may be preferable to mix the combustible material(s)
with the liquid mixture while the liquid mixture is still hot. In
one embodiment, the plant oil(s) and wax(es) are at a temperature
of about 250.degree. to about 350.degree. Fahrenheit when the
combustible material(s) is(are) added. The mixture of combustible
materials, plant oils and waxes is thoroughly mixed to form a
blended fire log composition also referred to as a pasta
mixture.
[0041] In another embodiment, the pasta is made by mixing the plant
oil(s) and about 80% of the wax(es). The combustible material(s)
is(are) then added. After these ingredients have been mixed, the
remaining about 20% of wax(es) is(are) added to the mixture.
[0042] The desired lengths of the log may be about 8 to about 15
inches long. The desired densities of the log may be about 45 to
about 75 lbs/ft3. In a particular embodiment, pasta is extruded and
a log is produced having a length of about 12 inches and a density
of about 66 lbs/ft3. Because the size and density of log depends on
the oil/wax/combustible material ratios in the composition of
pasta, the amount of force exerted during extrusion and the design
of the extrusion die may vary. Other embodiments may include other
ranges of pasta, extrusion forces, and extrusion dies necessary to
produce a log of about 8 to about 15 inches long and density of
about 45 to about 75 lbs/ft3.
[0043] Preferably, according to an embodiment of the present
invention, pasta is extruded using a single screw or twin screw
extruder and an extrusion die to produce logs with grooves, e.g.,
V-shaped or square-shaped grooves, formed therein that is believed
to improve the ease of ignition and burning performance of the log.
First, the grooved log is easier to light. The grooves increase the
surface area of the log allowing for more of the combustible
material(s), plant oil(s) and wax(es) to be exposed. Second, the
groves provide an edge or lip for improved ignition of the fire log
and promote a more pleasing flame appearance while burning. Third,
the longitudinal grooves also provide a path for superior flame
propagation. The increased surface area and the provision of edges
for flame propagation result in a log with improved ignition
properties. Fourth, the grooved log burns more completely with a
more consistent flame size. The increased surface area allows for
better and more complete combustion of the materials of the log
during the burn. This, it is believed, leads to a hotter burn. A
hotter burning log allows more of the combustible material(s),
plant oil(s) and wax(es) to completely burn thus, reducing
emissions and the production of ash. Having the log burn hotter has
the environmental benefit of reducing emissions from the combustion
process.
[0044] The grooves also control the direction of the flames,
allowing the log to burn more evenly and completely. The grooves
guide the direction of the burning across the entire log and
inward. This results in the entire log burning with little unburned
material remaining. Having the log burn more evenly and completely
has the additional environmental benefit of not having the user
dispose of excessive unburned ash into landfills. And as mentioned,
the grooved log provides a more pleasing appearance to the user
while burning.
[0045] According to one embodiment of the present invention, since
the plant oil(s)/wax(es) mixture or blend is of a significantly
higher melting point than conventional manufactured logs, operating
variables and operating costs of the extrusion process are reduced
because it allows for extrusion at higher temperatures. This
process according to this embodiment of the invention allows for
the production of a harder, more durable log. FIGS. 1A and 1B
illustrate log configurations according to exemplar embodiments of
the present invention.
[0046] According to a preferred embodiment (referring to FIG. 2),
the process of the present invention includes, for example, the
following steps (the order of which may vary or be combined, if
practical and desired):
Raw Material Addition
[0047] Wood fiber(s) (or any other combustible materials employed)
is(are) mechanically conveyed from a storage silo to a weigh belt
or volumetric feeder. The weigh belt feeder measures the weight (in
pounds per minute and pounds per hour) of wood fiber being added
into the high intensity mixer while the volumetric feeder measures
the volume of a known bulk density wood fiber and converts this to
weight being added into the high intensity mixer. A molten liquid
blend of oil(s)/wax(es) flows from a storage tank via a heat-traced
pipe into the mixer. The flow rate may be measured using a mass
flow meter and the rate of addition may be ratio controlled
relative to the wood fiber in order to produce a pasta of the
proper combination of liquid blend and combustible material. The
temperature of the molten liquid blend is controlled at about
200.degree. F. to about 350.degree. F. (preferably, at about
250.degree. F. to about 350.degree. F.), depending on the physical
properties of the liquid blend and the water content of the wood
fiber. If water content is higher than desired, the liquid blend is
added at a higher temperature in order to remove some of the
contained water by heat flashing.
Mixing
[0048] A horizontal paddle mixer may be utilized, but there are
other mixers that would work as well. The wood fiber and the liquid
blend are added at the same end of the continuous mixer (the feed
end) in order to allow maximum residence time in the mixer to
produce a consistent pasta. The mixer may be an adjustable overflow
outlet weir that allows for fine tuning of the residence time in
the mixer. The mixer preferrably has an external heating jacket and
also can be equipped with heating for the mixer shaft and paddles.
Steam is added to the jacket (and the mixing paddles if desired) in
order to control the mixing temperature in a range of approximately
170.degree. F. to approximately 250.degree. F., preferably about
200.degree. F. If the temperature is too high, the pasta will tend
to be "wet", indicating the liquid blend is still in the molten
state, and difficult to convey and cooling of the pasta will be
more difficult resulting in reduced production rates and cracking
of the fire log upon extrusion. If the temperature is too low, the
pasta will tend to over solidify resulting in sticking and coating
of the internal surfaces of the mixer. The mixer speed and level in
the mixer are controlled to provide adequate mixing intensity and
to maintain adequate residence time in order to achieve a uniform
pasta mix.
Cooling
[0049] The hot pasta is discharged from the mixer and via gravity,
mechanical conveying, and/or pneumatic conveying flows to a
continuous cooler. In the cooler, the pasta is cooled to a
temperature of about 70.degree. F. and about 130.degree. F.,
preferably about 100.degree. F., prior to extrusion. Chilled air
flowing countercurrent to the pasta is preferably used for cooling.
Air temperature is controlled at about 30.degree. F. and about
60.degree. F., preferably about 40.degree. F., entering the cooler.
Flow rate of air can be varied in order to achieve the proper pasta
temperature exiting the cooler. However, too much air flow will
fluidize the pasta to the point of carrying material out of the
cooler with the air and overloading or plugging the cyclone. Too
little air flow will result in pasta exiting the cooler at too high
of a temperature and will contribute to plugging in the cooler.
Therefore, air flow and temperature must be balanced to achieve
adequate cooling while minimizing entrained pasta with the
discharging air.
Mixer/Feeder
[0050] The cooled pasta via gravity, mechanical conveying, and/or
pneumatic conveying flows from the cooler to the mixer/feeder. The
function of the mixer/feeder is to provide initial compression of
the pasta and additional mixing for homogeneity prior to
introduction to the extruder as the material is conveyed by this
equipment to the extruder. The mixer/feeder is a variable speed
machine that allows a controlled feed rate to the extruder for
optimum extruder operation. Additional cooling can be provided in
the mixer/feeder by the direct contact of pasta with cool air or a
cold gas such as carbon dioxide.
Extruder
[0051] The mixer/feeder conveys the pasta into the top of the
extruder (e.g., a single screw extruder). In the extruder, pasta is
compressed and pushed through the die at the exit end of the
extruder (See FIGS. 3 and 4, for example). Extruder speed is
controlled to provide for the desired production rate and
compression. The extruder screw (via a hollow shaft), the extruder
barrel and the die are temperature controlled either by heating
with steam or hot water or cooling with chilled water to control
the extrusion temperature. Typically, heating is used at the
start-up of the extrusion process. As additional heat is generated
by the extrusion process, a switch is made from heating to cooling
in order to control the pasta and log temperature. Without proper
temperature control, the extruder could be overloaded (caused by
feeding at too low of a temperature) or logs that crack and break
may be produced (caused by feeding at too high a temperature).
Temperature is controlled such that the temperature of the
discharging log is between about 70.degree. F. and about
130.degree. F., preferably about 100.degree. F.
EXAMPLES
[0052] Both laboratory and commercial scale tests were performed to
evaluate the burn characteristics of the logs. A description of the
laboratory scale test stand follows: after a particular log recipe
was mixed and a log was extruded according to the processes
described herein, the log was subjected to a burn test. The log was
lit on both bottom ends of the log. Burn characteristics were
observed and noted as they occurred. Noted burn characteristics may
include the ease of ignition, the flame (size and movement), heat
generation, log integrity (drip or breakage), level of smoke
generation, ash produced, and flame propagation. Total burn time
was noted. The logs were also measured or observed in relation to
total weight, log density, log durability upon handling, hardness,
heat exposure, and general appearance (presence of cracks, swelling
and the like).
Comparative Example I
[0053] A 2.5 pound log was produced in a single screw extruder with
about 47.5% pine sawdust and 52.5% molten liquid. The liquid was
composed of about 65% tall oil pitch and about 35% polyethylene
wax. The tall oil pitch was oxidized to an acid value of about 20
mg KOH/g sample. The liquid blend had a heat value of about 18,055
BTU/lb. The log was lit at 8:55 a.m. At 8:58 a.m., the log was
totally engulfed in flames. For the first 10 minutes, there was
some dripping of liquid on the ends of the logs. At 9:21 a.m., the
flames slowed to about 75% of full burn height and there was some
cracking of the log on top. At 9:52 a.m., the flames were at 65% of
full burn height and the log held together despite cracks. At 10:28
a.m., about one half inch of one end fell off and the log was at
approximately 40% full flame. By 10:50 a.m., the flame was at about
25%. The flame was out at 11:39 a.m. The log burned for 2 hours and
44 minutes. The log still had a little unburned material in the
center.
Comparative Example II
[0054] A 2.5 pound fire log was produced containing about 45% dry
sawdust and about 55% molten liquid. The molten liquid was composed
of about 93% oxidized tall oil pitch and about 7% polyethylene wax.
The log was a slightly soft with a density of around 64 lbs/ft3 and
swelled slightly when discharging from the single screw extruder.
At 9:15 a.m., the log was lit, the flame spread slowly. By 9:30
a.m., the back of the log was fully lit, but not the front. Cracks
started to develop on the top of the log. At 10:40 a.m., the log
was out without the front ever igniting. At 10:45 a.m., the log was
re-lit and in five minutes became fully engulfed. By 10:55 a.m.,
the log was dripping and cracking. At 11:15 a.m., the log stopped
dripping and the log was burning well. At 12:00 a.m., the flame was
out and the log was fully burned resulting in a total burn time of
2 hours and 45 minutes.
Exemplary Example I
[0055] A 5 pound fire log wax made of about 48% wood flour and
about 52% molten liquid blend. The liquid blend was composed of
about 80% modified (saponified, neutralized, distilled, and
acidulated) tall oil pitch residue and about 20% polyethylene wax
and had a viscosity of approximately 29 centipoise at 300 degrees
Fahrenheit and a drop melt point of about 223 degrees Fahrenheit.
The log was wrapped in a paper wrapper. The wrapper was lit in
order to ignite the log at 6:45 a.m. The log became totally
engulfed in flames at 6:50 a.m. and the log burned until 10:15
a.m.
Exemplary Example II
[0056] A 6 pound fire log was produced by extrusion and was
composed of about 44% wood flour and about 56% molten liquid blend.
The liquid blend was composed of about 75% modified (saponified,
neutralized, distilled, and acidulated) tall oil pitch residue and
about 25% polyethylene wax. The liquid blend had a viscosity of
approximately 23 centipoise at 300 degrees Fahrenheit and a drop
melt point of about 228 degrees Fahrenheit. The log was wrapped in
a paper wrapper and at 8:30 a.m. lit by lighting the paper wrapper.
The log became totally engulfed in flames by 8:37 a.m. and burned
until 12:25 p.m. Flame height was very good during about 95% of the
burn time.
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