Note: Descriptions are shown in the official language in which they were submitted.
8 5 1
MEYC:002
FUEL COMPOSITION AND METHOD OF MANUFACTURE
This invention relates to a fuel composition and to a
method of manufacturing a fuel composition. The invention
may have specific application in making carbonaceous fuel
supplies, such as coal, which are located in remote areas
available to populous areas. More particularly, this
invention relates to transportable fuel compositions
and to methods of making such compositions.
Over 200 billion tons of economically recoverable coal
exists in the United States o~ America. This represents
enough to lask the United States Eor at least three centu-
ries at the current consumption rate. It has been esti-
mated that coal could provide as much as one-half of the
new energy sources required between now and the year 2000.
Even though coal represents 60% of the domestic fossil
energy resources of the United States, it currently sup-
plies less than 20% of the energy production. A number offactors have combined to create this disparity. Even with
~he abundance of coal energy it has not heretofore been
competitive with, nor as'easily utilized asr hydrocarbon
containing fuels such as oil, natural gas and the like.
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One important use of United States coal resource is
in stationary power conversion facilities such as plants
producing electricity or process heat which do not require
the scarce liquid and gaseous hydrocarbon fuels. Sta-
- 5 tionary power conversion facilities can operate using coal
leaving the liquid and gaseous hydrocarbon fuels to trans-
portation and certain residential/commercial uses. Use of
coal in stationary power facilities requires either trans-
portation of the solid fuel to the power facility or utili-
zation of the solid fuel at the mine site. Utilization atthe mine site to produce electricity is not always effi-
cient due to transmission and/or conversion losses. Pro-
duction of electrical energy at other than the mine site
requires transportation of the coal. Coal is currently
shipped by rail in unit trains. However the required
handling is cumbersome, wasteful and expensive. The
current U.S. rail capacity is inadequate to move the
tonnage required to supplant existing use of more costly
and scarce liquid fuels.
A further attendant problem with the use oE solid
fuels yenerally, and coal specifically, is that not all
solid ~uels contain the same mixture of constituents. For
example weste~n U.S. coal, while being low in sulfur, is
also low in BTU per unit weight and has a high water con-
tent. Eastern U.S. coal on the other hand haa a higher
sulfur and BTU content per unit weight but lower water.
Each requires specific pollution control equipment and a
certain boiler system. Therefore~ coal is not as uniform
a fuel as is, for example, #6 fuel oil or the like.
Additionally, coal from whatever source contains
various pollutants which heretofore have been difEicult
or impossible to remove. The nature and amount of these
depends upon the geographical area from which the coal
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is mined. Ash, sulfur, and nitrogen comprise the most
objectionable of these pollutants.
Recently developed process technology permits the
conversion of coal to synthetic liquid or gaseous fuels
at the mine site. While this "synfuel" is more easily
transported than coal, the conversion process is capital
intensive and requires a great deal of water. Despite the
high processing costs, the resultant synfuel, like crude
oil derived fuels, is valuable as a transportation fuel.
In addition to being useful as transportation ~uels,
hydrocarbon containing fuels, including synfuels, are
likewise valuable as feedstock for the manufacture of
chemical synthetics including all types of plastics,
elastomers, resins, polymers and the like. It would
therefore appear advantageous to ulitize coal for sta-
tionary energy neéds while utilizing the liquid crude
supply and synfuels for transportation as well as feed-
stock purposes.
In order to move coal over long distances, methodshave been proposed for creating so-called "coal slurries"
which comprise a pulverized, comminuted or ground coal
admixed with water, and which may contain var~ous addi-
tives to, for example, increase the wetability of the
coal. This slurry, while capable of being transmitted
by pipeline, requires special pipelines and pumping
e~uipment. ~queous coal slurries have additional draw-
backs. First the water which is necessary to slurry thecoal is in short supply at the geographic region of the
western U.S. coal reserve. Second, water must be removed ~ ;
from the slurry prior to introduction of the fuel into a
f urnace or boiler.
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Non-aqueous or hydrocarbon containing liquid can also
be used as the transmission medium to form a slurry o~
pulverized coal~ These slurries still have attendant
problems. Non-aqueous coal slurries also require special
pipelines and pumping equipment. Since coal is still the
main fuel constituent in such slurries, furnace and stack
modifications are still required to burn coals from
different regions. Non-aqueous fractions, unlike aqueous
solutionsl tend to solubilize constituents as well as
impurities in the coal. This renders the slurrying liquid
substantially unusable as a feedstock for many chemical
syntheses. Additionally, burning of the slurry mixture
results in emission of the pollutants present in the coal.
Coke is an expensive product which is produced from
metallurgical coal. Methods have been proposed for
producing coke slurry by adding coke which has been formed
by conventional specialized coke production techniques, to
certain hydrocarbon materials. Coke is an agglomerated
material which has poor fluidity. It does, therefore, not
form a readily transportable slurry which can be effec-
tively conveyed in conventional pipeline systems. Coke,
being an agglomerated product, tends to settle out. Coke
particles, because of their surface and yeometric char-
acteristics, and because of their agglomerated structure,do not roll over each other and do not pack effectively.
Thus it would be highly advantageous to have a fuel
mixture easily prepared from coal which would be trans-
portable using existing pipeline systems; which would beburnable in substantially all existing boiler systems
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with little or no modificatioll regardless of the region
from which the solid fuel was obtained; which would be
high in BTU content per unit volumei and which would be
low in ash, sulfur and nitrogen pollutants.
According to one aspect of this invention there is
provided a fuel composition comprising a liquid-solid
admixture including a portion of a particulate coal char
material derived from coal dispersed in an amount of a
liquid organic material effective to produce a fluidic,
combustible/ transportable composition.
The invention further extends to a method of producing
a fuel composition, which comprises admixing a particulate coal
char derived from coal with an amount of a liquid organic material
effective to produce a fluidic, transportable, combustible
composition.
In one embodiment of the invention the coal char may be
produced by the pyrolytic distillation of coal in the absence
of oxygen, and the liquid organic material may be derived entirely
or at least partially from the pyrolytic clestructive distillation~
In an alternative embodiment of the invention, the
liquid organic material may be a ~ower chain alcohol o~ from
1 to about 4 carbon atoms.
The invention also encompasses the novel method of pro-
ducing a combustible fuel composition which comprises the steps
of subjec~ting coal to pyrolytic destructive thermal distillation
in the absence of oxygen to produce a particulate coal char,
and an organic liquid fractioni reducing the char to a sized
particulate to effect bimodal or trimodal packing; beneficiating
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the particulate to produce a substantially pollutant free
beneficiated particulate char; separating the organic liquid
fraction into an upper boiling pyrolysis fraction which
contains sulfur and nitrogen compounds and a lower boiling
pyrolysis fraction which is substantially free from such
sulfur and nitrogen compounds, and admixing the beneficiated
particulate cbar and an organic liquid selected from *he group
consisting of the lower boiling pyrolysis frac~ion, lower
chain alcohols and mixtures thereof in proportions such that
the particulate char is no less than about 45% by weight.
It has been discovered that such an admixture of a
particulate coal char and a liquid organic fraction ~i~lds
a transportable fuel composition which has high BTU per
unit volume, is low in pollutants, and can be a generally
- lS universal fuel for most boilers with little or no modifi-
cation.
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The composition o this invention is formed to create
a composition which has fluidic characteristics such
that it can be transported by certain existing pipeline
facilities.
The liquid organic fraction which acts as a continuous
phase in the admixture does not contain the impurities of
the prior art slurries and thus is capable of being sepa-
rated from the liquid-solid mixture prior to the ignition
o the char. The separated liquid is then available for
use as a feedstock for synthesis of chemical compounds.
Economically, the liquid organic fraction is derived
during the pyrolysis of the coal. Advantageously both the
char and the liquid organic fraction are beneficiated. The
fuel composition of the instant invention can be produced
by subjecting coal to pyrolytic destructive distillation in
the absence of oxygen to produce a particulate char which
is admixed in suitable proportions with a liquid organic
fraction to produce a liquid/solid fluidic mixture.
In accordance with one aspect of the invention the
combustible liquid-solid mixture is produced by firs~ sub-
jecting coal to pyrolytic destructive thermal distillation
in the absence of oxygen to produce a coal char. The char
is then pulverized or otherwise ground to produce a partic-
ulate matter. The particulate matter is then beneficiated
to produce a substantially pollutant-free char material.
The lower boiling organic fraction obtained from the pyroly-
sis of coal is admixed with the particulate beneficiatedchar in proportions so as to form the fluidic, solid-liquid,
combustible fuel mixture. Advantageously, the lower boiling
organic fraction used does not contain sulfur or nitrogen
pollutants.
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In accordance with another embodiment, the benefi-
ciated particulate char is admixed with a lower chain
alcohol which is produced by well known synthetic methods
utilizing coal and water or natural gas.
The utilization of char allows a high packing of
the solid particulate matter for a given fluidity of the
mixture. Thus not only does one obtain the aforementioned
advantages but the energy requirement necessary to pump a
IQ single BTU of fuel energy is significantly reduced,
In a further advantageous embodiment the ground,
beneficiated char is sized to yield a particulate distri-
bution which is bi-modal or tri-modal. The use of a
bi-modal or tri-modal particulate char distribution
greatly enhances the packing of the solid.
A preferred embodiment of the invention is now
described by way of example with re~erence to the accom-
panying drawing. The drawing is a flow diagram of oneembodiment of the process of the instant invention.
The drawing shows a schematic of process step~ for
producing a coal derived f~el composition of the instant
invention wherein raw coal 12 from a coal mine 10 is
conveyed continuously to a crusher means 14. Within
crusher means 14 the raw coal 12 is fragmented to parti-
cles in the range of 1/2" to 1/4" in diameter to produce a
crushed coal product 16. The crushed coal 16 is conveyed
continuously to a pyrolytic destructive distillation means
18 which preferably contains 3 preheating chamber to
remove moisture and entrained gases. The pyrolytic
destructive distillation means 18 provides for thermal
destructive distillation of the coal in the absence of
ox~gen to produce a char portion 20 and a liquid organic
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fraction 34. The char portion 20 is continously conveyed
to a grinding means 22. Within the grinding means 22 the
char is pulverized or otherwise comminuted to produce a
~round char product 24 which is inherently spherical in
- 5 shape. The ground char 24 is conveyed to a beneficiation
means 26. Within the beneficiation means 26 the ground
char 24 is beneficiated by removal of undesirable consti-
tuents and pollutants such as sulfur and ash. The open
pore structure of the char facilitates this process. The
beneficiated char 28 is conveyed to a particulate sizing
means 30. Within the sizing means 30 the particulate is
mechanically separated by particle size to produce a sized
distribution of particulate char. The sized char mixture
32 is continously conveyed to a mixing means 42.
The liquid organic fraction 34 is conveyed from the
pyrolytic destructive distillation means 18 to a separa-
tion means 36 where the higher boiling fraction 38 contain-
ing the bulk of the nitrogen is separated for example by
distillation from the remainder and conveyed to storage
for use directly as a chemical reagent and feedstock.
Within the separation means 36, the lower boiling fraction
40 is rendered substantially free of combined and entrained
materials which on combustion would produce sulfur oxides,
nitrogen oxidesl and like pollutants. The lower boiling
pollutant Eree fraction 40 is continuously conveyed to the
mixing means 42. Within the mixing rneans 42 the char
mixture 32 and the li~uid lower boiling fraction 40 are
combined in appropriate proportions to produce the easily
transportable char containing fuel composition 44 of the
instant invention which is passed to storage 46 for
distribution by pipeline or tanker vehicle in a manner
similar to crude oil.
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The coal that can be employed in accordance with the
instant invention can be generally termed "combustible
carbonaceous material". It is any of the combustible,
carbon containing materials that will undergo pyrolytic
destructive distillation to form char. Such materials
comprise carbon containing shales, anthrasite coal,
bituminous coal, and all of the soft coals, lignites, and
the like.
The rnining and preparation of coal is fully described
in Kirk-Othmer ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, second
edition, Anthony Standin, editor, Interscience Publishers,
New York, 1969, vol. 5, pp. 606-676. The coal is mined
from a coal mine by either strip or underground methods as
appropriate and well known in the art.
The raw coal material 12 is preferably subjected
to preliminary crushing to reduce the particle size.
Particle sizes of from 1/2" to about 1/4" in lateral
dimension (diameter) are found useful, with particles of
about 3/8" being preferred. The need for size reduction
and the siz~ of the reduced material will depend upon the
pyrolykic conditions utilized as well as the composition
of the coal material. The crushiny and/or grinding is
preferably accomplished with impact mills such as counter-
rotating cage mills, hammer mills of the like. This is
done to impart an impact type shock to the coal to sepa-
rate material along natural planes, faulted surfaces,
solution channels and the like. Within the crusher means
14 the coal is sized by, for example, rough screening and
gangue material is removed to assure a more uniform
product for pyrolysis. Advantageously, carbonaceous fines
and the like are readily utilized and can be separated
from the macro coal particles and conveyed directly to the
pyrolytic destructive distillation means 18. The macro
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coal particles are passed continously through a preheater
within pyrolytic destructive distillation means 18 which
is operated at 150 to 220F in order to remove gases and
moisture. This is a well known process and is of value in
- 5 that the BTU content of the resultant coal per unit weight
is increased. This preheating also removes certain en-
trained gases which may have further ~alue as fuel for the
pyrolysis step.
The pyrolytic destructive distillation means 18 can
~e any pyrolysis apparatus which is well known in the art.
Preferably, the pyrolysis is performed in a continuous
process. As the crushed coal 16 is heated in the absence
of oxygen, the entrained materials are vaporized and
collected. Lower boiling organic fractions including
hydrocarbons, cyclics, and aromatics as well as higher
boiling organic fractions are emitted from the coal
leaving a char material of essentially carbon which is of
a porous structure and substantially spherical in shape.
Included in the emitted constituents are the nitrogen
containing polluting compounds such as pyri~ine, pipera-
zine and the like.
The char 20 is continually conveyed to the grindiny
means 22. The grinding means 22 reduces the char to a
suitable fineness to facilitate beneficiation and subse-
quent sizing for use in the fuel admixture. Any conven-
tional crushing and grinding means, wet or dry, may be
employed. This would include ball grinders, roll grind-
ers, rod mills, pebble mills and the like. Advantageously,the particles are sized within the grinding means 22 and
recycled to produce a uniform distribution of particles.
The char particles are of sufficient fineness to pass a
10 mesh screen and the majority of the particles are in
the 100 to 200 mesh size. The mesh sizes refer to the
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Tyler Standard Screens. The char 24 is continuously con-
veyed to the beneficiation means 26.
The beneficiation means 26 can be any device known
in the art utilized to extract pollutants and other unde-
sirable inorganics such as sulfur and ash from a particu-
late char material. This can be done for example, by
washing, jigging, extraction, flotation, chemical reaction,
and/or electrobeam techniques. The exact method employed
will depend largely on the coal constituent utilized in
forming the char, the sizes of the char particles and the
conditions of pyrolysis.
The beneficiated char 28 is sized in particulate
sizing means 30 which can be any apparatus known in the
art for separating particles of a size in the order of 100
microns. Economically, screens or sieves are utilized,
however cyclone separators of the like can also be employed.
In sizing selections made so as to assure combustion, a
second and/or third particle size is chosen to effect so-
called "modal" packing. The spheriod shape of the primary
particle provides spacing or voids between adjacent parti-
cles which can be filled by a distribution of second or
third finer particle sizes to provide bi-modal or tri~modal
packing. Thi~ packing concept allows the compaction oE
substantially more fuel in a given volume of fuel mixture
while still retaining good fluidity.
The resultant char mix 32 is conveyed by means of for
example an air conduit to the mixing means 42 where it is
combined in appropriate proportion with the lower boiling
organic fraction 40.
Simultaneously, with the preparation of the char,
the organic fraction 34 entering the separation means
36 is continuously fractionally distilled or otherwise
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separated to provide the lower boiling pollutant free
organic fraction 40. The exact amount of this fraction
utilized will depend upon the properties of the combusti-
ble char containing admixture which are desired. Nor-
mally, fractions having boiling points up to about 200Fhave been found useful in carrying out the instant inven~
tion~ Any remaining pollutant fraction could be separated
by other means as, for example, steam stripping.
The higher boiling fractions 38 of the liquid organic
fraction 34 advantageously contain certain sulfur and
nitrogen compounds. This fraction is removed and can be
used directly as a feedstock for chemical synthesis.
Within the mixing means 42 the particulate char and
the lower boiling pollutant-free organic fraction 40 are
admixed in the desired proportions and sent to storage 46.
In the mixing means, an admixture is formed of char and
the liquid constituent. The ratio of char to liquid that
can be utilized will depend upon the properties of the
fuel desired. For most applications the char constituent
should comprise not less than about ~5% hy weight of the
composition and preferably from about 45% to about 75~ hy
weight. The mixing means 42 can be any well known mixing
apparatus in which an organic constituent and a coal char
can be mixed together in specific proportions and pumped
continuously to a storage tank such as 46.
Certain well known surfactant stabilizers may be
added depending on the viscosity and non-settling charac-
teristics desired. Within the storage tank 46 it is
generally not required to agitate the fuel admixture of
the instant invention unless such storage is to be for an
extended period. From the storage tank the fuel of the
instant invention is preferably continuously conveyed by
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means of pipelines well known in the art to distant fixed
source heat and electric generators.
It will be realized that the liquid organic fraction
; - 534 derived from the pyrolytic destructive distillation of
coal can be utilized directly as a feedsto~k for chemical
synthesis, transportation fuels or the like rather than as
the liquid phase of the instant fuel admixture.
10In accordance with another embodiment of the instant
invention coal and water are utilized to produce first CO
and H2 and then methanol and other lower alcohols which
are utilized as the liquid phase for the combustible fuel
admixture of the instant invention. Water released ~rom
the coal during preheating can be used as part of the
water required in the synthesis, thus further preserving
precious resources.
As used herein the term alcohol is employed to mean
~0 alcohols which contain from 1 to about ~ carbon atoms.
These include for example, methanol, ethanol, propanol,
butanol and the like. The alcohol may range Erom substan-
tially pure methanol to various mixtures of alcohols as
are produced by the catalyzed reaction of synthesis gas or
natural gas. Advantageously, the alcohol constituent can
be produced on site at the mine in conjunction with the
pyrolytic destructive distillation. The process can be
fired by coal, thereby negating the necessity to transport
fuels long distances.
In accordance with the process for making these alco-
hols directly from coal and steam, carbon monoxide and
hydrogen are initially formed in accordance with equation
I:
I. HOH (steam) ~ C(coal~ CO+H2
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A portion of the gas is subjected to the shi~t reaction
with steam to produce hydrogen for hydrogen enrichment
in accordance with equation II:
- 5 II. CO + HOH (steam) CO2+H2.
The CO2 is scrubbed from the gaseous product leaving only
hydrogen. The hydrogen is admixed with gaseous products
of equation I to produce a "syn gas" having desired ratio
of hydrogen to carbon monoxide from which methanol and
similar products are synthesized catalytically.
In the methanol synthesis plant the respective consti-
tuents such as carbon monoxide and hydrogen are combined to
produce methanol. The synthesis of methanol is described
in page 370-39~ of vol. 13 of the above referenced KIRK-
OTHMER ENCYCLOPEDIA. The car~on mono~ide and hydrogen are
controlled in a ratio and temperature pressure combination
to obtain maximum yields of the methanol fuel product.
Other methods for methanol synthesis at low~r temperatures
and pressures are also known, as for e~ample, the ICI low
pressure process as described in "Here's how I~I Synthesizes
Methanol at Low Pressure" Oil and Gas Journal, vol. 66,
pp. 10~-9, February 12, 1968. In accordance with this
aspect of the instant invention, the methanol is used as
the liquid phase to slurry the char 32 in mixing means 42.
It will be realized that in accordance with the instant
invention surfactants, suspenders, organic constituents and
the like may be added depending on the particular applica-
tion. As hereinbefore mentioned, advantageously the admix-
ture of the instant invention demonstrates high fluidity.
Thus high ~TU per unit volume are obtained with lower vis-
cosities and higher fluidities.
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It will be realized that the lower boiling organic
fraction and/or the synt~esized methanol will not dissolve
or otherwise solubilize impurities since the coal has been
charred and the char has been beneficiated. Thus the
liquid phase of the composition can be readily extracted
at the fuel mixture destination for use as a chemical syn-
thesis ~eedstock. Additionally the fuel composition of
the instant invention can be mobilized or transported by
all conventional means used for crude oil transportation,
permitting the efficacious foreign export of coal derived
fuels which has not heretofore been readily and easily
accomplished. For example the existing pipelines to docks
and tanking facilities can readily be utilized. Oil tank-
ers can empty their crude oil load in this country, and be
refilled with the char containing composition of the
instant invention which can be exported to other nations,
thus improving the balance of payments of this country.
The liquid solid admixture, upon reaching its ulti-
mate destination, may be employed directly as a fuel forheating; for utilities such as power plants; or or
process converters such as in the preparation of synthetic
materials. On the other hand it may be separated into its
constituents, char and the lower boiling organic fractions
and/or methanol. The char portion is employed as fuel,
while the organic fraction and/or methanol can be employed
as a feedstock or as a transportation fuel such as a gaso-
line additive or as an extender.
While the invention has been explained in relation to
its preferred embodiment it is understood that various modi-
fications thereof will become apparent to those skilled in
the art upon reading the specification and it is in~ended
to cover such modifications as fall within the scope of the
appended claims.
