Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CATALYTIC COAL PRODUCT AND METHOD O~ GASIFICATIOM
BACKGROUND OF THE INVENTION
Stambaugh et al United States Patent 4,092,125 discuss prior art
methods of impregnating coal with a catalyst by (a) physical
admixing of catalyst to coal or (b) soaking the coal in an aqueous
solu-tion of catalyst at room temperature and then drying the
slurry. Stambaugh et al discloses a method of treating fine
particles of solid carbonaceous fuel of a coal or coke type that
comprises mixing the fuel particles with a liquid aqueous solution
comprising essentially (a) sodium, potassium or lithium hydroxide
together with (b) calcium, magnesium or barium hydroxide or
carbonate.
Lancet in U.S. Patent No. 4,248,605 discloses a method
of gasifying the bottoms fraction from a coal liqueEaction process
by mixing the bottoms fraction with at least one finely divided
calcium compound selected from the group consisting of calcium
oxide, calcium carbonate and calcium hydroxide with the calcium
compound being of a size consist no larger than about minus 200
Tyler mesh and present in an amount sufficient to produce agglom-
erate particles upon mixing with the bottoms fraction and there-
after gasifying the resulting agglomerate particles by reacting
the agglomerate particles with steam in a fluidized bed.
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SUMMARY OF THE INVENTION
A ca-talyzed gasification process comprising providing a
mixture of finely divided solid particles of carbonaceous material
of a size smaller than 65 Tyler mesh and finely divided particles
o a calcium compound, of a size smaller than 65 Tyler Mesh and
gasifying the mixture of finely divided solid particles of car-
bonaceous material and finely divided par-ticles of calcium
compound.
A gasification feed product comprising a carbonaceous
suspension of a calcium compound made by heating a mixture of
finely divided carbonaceous particles of a size smaller than 65
Tyler mesh and finely divided particles of calcium compound of a
size smaller than 65 Tyler mesh.
The operable range of ratios of carbonaceous material
to calcium compound is from 98:2 to 30:70. ~ixtures of carbon-
aceous material and calcium compound within this range or ratios
with 10 percent or less than 10 percent calclum compound are
preferred for catalyzed gasiication. Whlle mixture o carbon-
aceous material and calcium compound within this range or ratios
with 10 percent or more than 10 percent calcium compound are
preferred or raising the ash fusion temperature.
Throughout this specification and claims mesh means
Tyler mesh.
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DETAILED DISCUSSION OF T~E INVENTION
In the field of catalytic coal gasification, a problem
of continuing concern has been the chemical and physical incor-
poration of a suitable gasification catalyst in the coal. For
5 example, U.S. Patent No. 4,092,125 discloses a chemical and
physical incorporation of a suitable gasification catalyst in
coal by hydrothermally treating the coal. The coal thus treated
is a feedstock for a gasification.
The present invention is directed to a new feedstock
for gasification as well as a process of gasifying coal.
To carry out the present invention coal is ground and
mixed with grouncl calcium compound. This mixture of ground coal
and ground calcium compound is then gasified. ~ preferred coal
for use in the process of the present invention is bituminous
coal from Eastern United States called Eastern Coal. By the use
of the present invention Eastern coal is formed into an improved
gasification feedstock.
In a preferred embodiment of the invention, the mix-ture
of ground coal and ground calcium compound are pelletized prior
to gasification. For example, the mixtuxe of coal and calcium
compound may be briquetted.
In another preferred embodiment of the invention, the
mixture of ground coal and ground calcium compound is extruded in
an extruder into a gasifier for gasification.
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In coal gasification by the present invention coal may
be contacted with water by the following reaction
C + H20 ~ CO + H2 (I)
Additionally, the CO may react with water as ~ollows
CO + H20 ~ CO2 + H2 ~II)
The calcium compound in the ground coal- ground calcium
compound mixture may be calcium oxide which when heated in the
presence of C02 such as that formed in reaction II above would
react as follows
CaO + CO2 -~ CaC03 (III)
This reaction of calclum oxide with carbon dioxide is
exothermic and produces sufficient heat to maintain the desired
reaction temperature in the reactor wherein gasification is
occurrlng for high ratios of Ca to C.
Reactions I, II and III all occur in the reactor which
receives the pelletized mixture of finely divided carbonaceous
material and finely divided calcium compound.
The present invention relates to a catalyzed gasi-
fication process wherein the mixture of f.inely divided carbonaceous
material and finely divided calcium compound particles is gasified
after heating the mixture to form a carbonaceous suspension of
calcium compound whereby the calcium compound catalyzes the
gasification of the carbonaceous material. Because of the
intimate contact between the small particles of carbonaceous
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material and calcium compound in the mixture of solids, when the
solids mixture is liquified to form a suspension of calcium
compound in carbonaceous material, the distribution of calcium
compound in the suspension of carbonaceous material is sufficient
for catalysis of the gasification of carbonaceous material during
heating.
In a preferred embodiment of the invention, gasifica-tion
is carried out by maintaining the mixture of finely divided
carbonaceous material and finely divided calcium compound at 300
to 550C for from 1 to 30 minutes during which time the mixture
becomes a suspension of liquified carbonaceous material having
calcium compound intimately dispersed therethrough. More preferably,
the mixture of finely divided carbonaceous material and finely
divided calcium compound is maintained within the temperature
range of from 350 to 500C for 1 to 30 minutes. Most preferably,
the mixture of calcium compound and carbonaceous material is
maintained from 400 to 450C for about 20 minutes.
Preferred calcium compounds :Eor use in the present
invention as the finely divided calcium material include lime,
calcium carbonate or calcium hydroxide. Preferred carbonaceous
material for use as the finely divided carbonaceous material in
the present invention include Eastern U.S. bituminous coal, and
coal generally~ The suspension of catalyzed carbonaceous
material formed by the liquifying of a mixture of finely divided
carbonaceous material and finely divided calcium compound
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form a coke product. This coke product may be gasified by any
process which will accep~ coke or char as the feed. For example,
the coke product may be brlquetted and fed to a fixed bed gasifier
such as those described at pages 1634 to 1639 of Elliott, Chemistry
of Coal Utilization, Second Supplementary Volume, 1981. Alter-
natively, the product of the present invention may be fed by a
screw-type feeding system as the gasifier fuel such screw-type
feeder is shown in Fernandes, U.S. Patent 3,920,417. During
gasification -the mixture of carbonaceous material and calcium
compound may be contacted with molecular oxygen or air or steam
or rnixtures of the aforesaid air, oxygen and water. The water
preferably being in the form of steam. The carbonaceous material
and the calcium compound material in the mixture to be gasified
by the process of the present invention is preferably in a ratio
of 1:1 or greater. Most preferably for catalyzed gasification,
the mixture of carbonaceous material and calcium compound of the
present invention has 3 to 10 percent by weiyht calcium compound
material with the remainder of mixture being carbonaceous material
i.e. 90 to 97 weight percent carbonaceous material.
Within the scope of the invention is a gasi~ication
feed product having a carbonaceous suspension of calcium compound
made by heating a mixture of finely divided carbonaceous particles
of a size smaller than 65 mesh and finely divided calcium compound
particles of a size smaller than 65 mesh. The calcium compound
is preferably a compound of calcium selected from a group
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consisting o~ calcium oxide, calcium carbonate and calcium
hydroxide. More preEerably the particle size of both the finely
divided carbonaceous material and the finely divided calcium
compound is smaller than 100 mesh. Especially preferably
S the particle size of the finely divided calcium compound and the
finely divided carbonaceous material is less than 200 mesh. Most
preferred is finely divided calcium compound of particle size
less than 325 mesh.
The mixture of -65 mesh finely divided 90 to 97 weight
percent carbonaceous material and 3 to 10 weight percent calcium
compound gasifies catalyticly.
Mixtures of -65 mesh about 50% finely divided car-
bonaceous material and about 50% finely divided calcium compound
produce sufficient heat in the top of the gasifier to destroy
tars which would leave the gasifier with the product gas and
require additional processing to separate them.
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EXAMPLE 1
Ninety pounds of Eastern U.S. coal is ground to -65
Tyler mesh. Ten pounds of calcium oxide is ground to -200 Tyler
mesh. The finely divided Eastern U.S. coal and finely divided
calcium oxide are mixed. This mixture is extruded into the top
of a gasifier where the extrudate is melted, forming an intimate
calcium-melted coal suspension which upon coking formed a
catalyzed char. This catalyzed char ls then gasified upon moving
down the bed.
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EXAMPLE 2
Ninety-five pounds of Eastern U.S. coal is ground -to
-100 Tyler mesh. Five pounds of calcium oxide is ground to -200
Tyler mesh. The finely divided Eastern U S. coal and finely
divided calcium oxide are mixed. This mixture is extruded into
the top of a gasifier where the extrudate is melted, forming an
intimate calcium-melted coal suspension which upon coking formed
a catalyzed char. This catalyzed char is then gasified upon
moving down the bed.
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EXAMPLE 3
Ninety-two pounds of Eastern U.S. coal is ground to
~100 Tyler mesh. Elght pounds of calcium oxide is ground to -200
Tyler mesh. The finely divided Eastern U.S. coal and finely
divided calcium oxide are mixed. This mixture is extruded into
the top of a gasifier where the extrudate is melted, forming an
intimate calcium-melted coal suspension which upon coking formed
a catalyzed char. This catalyzed char is then gasified upon
moving down the bed.
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EXAMPLE 4
Ninety pounds of Eastern U.S. coal is ground to -65
Tyler mesh. Ten pounds of calclum oxide is ground to -20Q Tyler
mesh. The finely divided Eastern U.S. coal and finely divided
calcium oxide are mixed. This mixture is briquetted and fed into
the top of a fixed bed gasifier where the briquettes melt, forming
catalyzed char. This catalyzed char is then gasified upon moving
down the bed.
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^ EXAMPLE 5
Ninety~five pounds of Eastern U.S. coal is ground to
-100 Tyler mesh. Five pounds of calcium oxide is ground to -200
Tyler mesh. The finely divided Eastern U.S. coal and finely
divided calcium oxide are mixed. This mixture is briquetted and
fed into the top of a fixed bed gasifier where the briquettes
melt, forming catalyzed char. This catalyzed char is then
gasified upon moving down the bed.
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EXAMPLE 6
Ninety pounds of Eastern U.S. coal is ground to -65
Tyler mesh. Ten pounds of calcium oxide is ground to -200
Tyler mesh. The finely divided Bastern U.S. coal and finely
divided calcium oxide are mixed. This mixture is briquetted and
fed into the top of a moving bed gasifier where the briquettes
melt, forming catalyzed char. This catalyzed char is then gasified
upon moving down the bed.
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The procedure of the invention shows increases of
gasification reaction rates 3 to 6 times those of uncatalyzed
pior methods.
Having thus described the present invention by reference
S to certain of its preferred embodiments, it is respectfully
pointed out that the embodiments set forth are illustrative
rather than limiting in nature and that many variations and
modifications are possible within the scope of the present
invention. It is expected that many such variations and modifi-
cations will appear obvious and desirable to those skilled in theart based upon a review of the foregoing description of preferred
embodiments.
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