U.S. patent application number 11/066059 was filed with the patent office on 2006-08-31 for process for preparing a synthetic fuel from solid, combustible materials.
Invention is credited to Eric Ferrall, Michael Spradling.
Application Number | 20060191192 11/066059 |
Document ID | / |
Family ID | 36930777 |
Filed Date | 2006-08-31 |
United States Patent
Application |
20060191192 |
Kind Code |
A1 |
Ferrall; Eric ; et
al. |
August 31, 2006 |
Process for preparing a synthetic fuel from solid, combustible
materials
Abstract
The invention is directed to a process for preparing a synthetic
fuel from solid, combustible materials by treating these materials
with a water-redispersible polymer powder composition.
Inventors: |
Ferrall; Eric; (Saline,
MI) ; Spradling; Michael; (Ann Arbor, MI) |
Correspondence
Address: |
BROOKS KUSHMAN P.C.
1000 TOWN CENTER
TWENTY-SECOND FLOOR
SOUTHFIELD
MI
48075
US
|
Family ID: |
36930777 |
Appl. No.: |
11/066059 |
Filed: |
February 25, 2005 |
Current U.S.
Class: |
44/550 |
Current CPC
Class: |
Y02E 50/10 20130101;
C10L 5/44 20130101; C10L 5/46 20130101; C10L 5/04 20130101; Y02E
50/30 20130101; C10L 5/361 20130101 |
Class at
Publication: |
044/550 |
International
Class: |
C10L 5/00 20060101
C10L005/00 |
Claims
1. A process for preparing a synthetic fuel from solid, combustible
materials, comprising treating the combustible materials with a
water-redispersible polymer powder composition.
2. The process of claim 1, wherein the solid, combustible material
is selected from the group consisting of coal, wood, and waste
plastic materials.
3. The process of claim 1, wherein the water-redispersible polymer
powder is based on one or more monomers selected from the group
consisting of vinyl esters, (meth)acrylates, vinyl aromatics,
olefins, 1,3-dienes and vinyl halides and, if required, further
monomers copolymerizable therewith.
4. The process of claim 1, wherein the water-redispersible polymer
powder comprises one or more polymers selected from the group
consisting of homopolymers and copolymers of vinyl ester monomers;
copolymers of vinyl acetate and ethylene; copolymers comprising
vinyl acetate, ethylene and a vinylester of at least one a-branched
monocarboxylic acids having 9 to 11 C atoms, said homopolymers and
copolymers optionally containing one or more auxiliary
monomers.
5. The process of claim 1, wherein the redispersible polymer powder
composition is metered onto the combustible material in dry form,
the mixture of combustible material and redispersible polymer
powder is transported along a conveyor, and is treated with water
or steam before entering a mill, where the combustible material and
polymer are thoroughly mixed.
6. The process of claim 1, wherein the solid, combustible material
is transported along a conveyor, is treated with water or steam,
and subsequently a redispersible polymer powder is metered onto the
coal carrying conveyor just before entering a mill, where the
combustible material and polymer are thoroughly mixed.
7. The process of claim 1, wherein the redispersible polymer powder
composition is metered onto the combustible material, and the
mixture of combustible material and redispersible polymer powder is
transported along a conveyor and a the mill where the combustible
material and polymer powder are thoroughly mixed, and water or
steam is introduced.
8. The process of claim 1, wherein the redispersible polymer powder
composition is metered onto the combustible material, and the
mixture of combustible material and redispersible polymer powder is
transported along a conveyor and into a mill where the combustible
material and polymer powder are thoroughly mixed, and after the
material exits the mill, the mixture is treated with water or
steam.
9. The process of claim 1, wherein the solid, combustible material
proceeds along a conveyor and is sprayed with an aqueous
redispersion of the redispersible polymer before entering a mill,
where the combustible material and redispersible polymer are
thoroughly mixed.
10. The process of claim 1, wherein the solid, combustible material
proceeds along a conveyor and is enters a mill, where an aqueous
redispersion of the redispersible polymer is added, and the mixture
is thoroughly mixed in the mill.
11. The process of claim 1, further comprising forming the mixture
of redispersible polymer powder and combustible material into
briquettes.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention concerns a process for preparing a synthetic
fuel from solid, combustible materials by treating these materials
with a water-redispersible polymer powder composition.
[0003] 2. Background Art
[0004] A synthetic fuel is a material which is generated by the
conversion of natural fuel materials, like coal, crude oil, natural
gas or wood. Basically there are two mechanism of
conversion-degradation processes and chemical reactions.
Degradation processes are well-known in the state of art. Typical
examples of synthetic fuel prepared by a degradation process are
synthetic oil or synthetic gas produced from coal, synthetic gas
produced from wood, and synthetic oil produced from crude oil.
Typical examples of synthetic fuel prepared by chemical reactions
are fuel materials obtained by acylation or alkylation of coal with
organic chemicals.
[0005] Usually the synthetic fuel materials are used for heating,
for examples in power plants for district-wide heating, in plants
for electric power generation, and for the production of coke.
[0006] U.S. Pat. No. 6,641,624 B1 claims a process of preparing
synthetic fuel from coal, by preparing a mixture of coal with an
aqueous polymer solution or an aqueous polymer emulsion, and a
glycol or glycerin diluent as the third component. In comparison
with the above mentioned methods this process has the advantage of
improved environmental acceptability. But it has the disadvantage,
that with aqueous solutions or emulsions, a high amount of water is
introduced. Typically an aqueous polymer emulsion has a solids
content of about 50%, the remainder being water. This large amount
of water must then be removed in order not to cause a dramatic
reduction of the BTU value of the synthetic fuel. In the method of
the U.S. Pat. No. 6,641,624 water is used to the extent of 1.5 to
2.5 times higher than the amount of coal by weight. The cost of the
diluent also renders the process less attractive economically.
SUMMARY OF THE INVENTION
[0007] An object of the invention is to provide a method of
preparing a synthetic fuel from solid, combustible materials and
polymer materials, which can be processed in common synthetic fuel
plant equipment, and which does not have the disadvantage of
introducing a high amount of non-combustible materials like water
into the fuel. These and other objects are achieved through the
addition of a water-redispersible polymer powder to solid,
combustible fuel components.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0008] The invention is thus directed to a process for preparing a
synthetic fuel from solid, combustible materials by treating these
materials with a water-redispersible polymer powder
composition.
[0009] Preferred solid, combustible materials are coal, for example
anthracite, bitumen or lignite. Preferred too is wood, for example
in the form of wood chips or saw dust. Waste plastic materials may
also be used in this process as a solid, combustible material. The
solid combustible material may therefore be selected from any
variety of combustible solids, either alone or in a myriad of
mixtures.
[0010] Redispersible polymer powders are characterized in that they
are readily redispersible after stirring with water, largely
breaking down into particles substantially indistinguishable from
those of the initial dispersions from which the powders are
prepared, and which react or associate with certain organic
materials. Redispersible polymer powders are commercially available
from Wacker Polymer Systems under the trademark Vinnapas.RTM.. The
polymers are preferably based on one or more monomers from the
group of vinyl esters, (meth)acrylates, vinyl aromatics, olefins,
1,3-dienes and vinyl halides and, if required, further monomers
copolymerizable therewith.
[0011] Suitable vinyl esters are those of carboxylic acids having 1
to 12 C atoms. Vinyl acetate, vinyl propionate, vinyl butyrate,
vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl
pivalate and vinyl esters of a-branched monocarboxylic acids having
9 to 11 C atoms, for example VeoVa9.sup.R or VeoVa10.sup.R (trade
names of Resolution Products), are preferred. Vinyl acetate is
particularly preferred.
[0012] Suitable monomers from among the acrylates and methacrylates
are esters of straight-chain or branched alcohols having 1 to 15
carbon atoms with acrylic acid or methacrylic acid. Preferred
methacrylates and acrylates are methyl acrylate, methyl
methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate,
propyl methacrylate, n-butyl acrylate, n-butyl methacrylate,
tert-butyl acrylate, tert-butyl methacrylate and 2-ethylhexyl
acrylate. Methyl acrylate, methyl methacrylate, n-butyl acrylate,
tert-butyl acrylate and 2-ethylhexyl acrylate are particularly
preferred. Preferred vinyl aromatics are styrene, methylstyrene and
vinyltoluene. A preferred vinyl halide is vinyl chloride. The
preferred olefins are ethylene and propylene, and the preferred
dienes are 1,3-butadiene and isoprene.
[0013] If required, 0.1 to 5% by weight, based on the total weight
of the copolymer, of auxiliary monomers may also be copolymerized,
preferably, 0.5 to 2.5% by weight. Examples of auxiliary monomers
are ethylenically unsaturated mono- and dicarboxylic acids,
preferably acrylic acid, methacrylic acid; ethylenically
unsaturated carboxamides and carbonitriles, preferably acrylamide
and acrylonitrile; and ethylenically unsaturated sulfonic acids and
their salts, preferably vinyl sulfonic acid and
2-acrylamido-2-methylpropane sulfonic acid. Further examples are
precrosslinking co-monomers such as polyethylenically unsaturated
comonomers, for example divinyl adipate or triallyl cyanurate, or
postcrosslinking comonomers, for example N-methylolacrylamide
(NMA), N-methylolmethacrylamide, alkyl ethers, such as the
isobutoxy ether, or esters, of N-methylolacrylamide. Comonomers
having epoxide functional groups, such as glycidyl methacrylate and
glycidyl acrylate, are also suitable. Further examples are
comonomers having silicon-containing functional groups, such as
(meth)acryloyloxypropyltri(alkoxy)silanes, vinyltrialkoxysilanes
and vinylmethyldialkoxysilanes.
[0014] The choice of monomers or the choice of the amounts by
weight of the comonomers is made in such a way that in general a
glass transition temperature (Tg) of -50.degree. C. to +50.degree.
C., preferably -30.degree. C. to +40.degree. C., and most
preferably -5.degree. C. to +15.degree. C., is obtained. The glass
transition temperature Tg of the polymer can be determined in a
known manner by means of differential scanning calorimetry (DSC).
The Tg can also be calculated approximately beforehand using the
Fox equation. According to T. G. Fox, BULL. AM. PHYSICS SOC. 1, 3,
page 123 (1956), the following is applicable:
1/Tg=x.sub.1/Tg.sub.1+x.sub.2/Tg.sub.2+ . . . +x.sub.n/Tg.sub.n,
where x.sub.n is the mass fraction (% by weight/100) of the monomer
n and Tg.sub.n is the glass transition temperature in Kelvin of the
homopolymer of the monomer n. Tg values for homopolymers appear in
POLYMER HANDBOOK, 2nd Edition, J. Wiley & Sons, New York
(1975).
[0015] Particularly preferred are vinyl acetate homopolymers,
copolymers of vinyl acetate with ethylene, copolymers of vinyl
acetate with ethylene and with one or more other vinyl esters,
copolymers of vinyl acetate with ethylene and (meth)acrylic
ester(s), copolymers of vinyl acetate with (meth)acrylates and
other vinyl esters, copolymers of vinyl acetate with ethylene and
vinyl chloride, copolymers of vinyl acetate with acrylates,
styrene-acrylic ester copolymers, and styrene-1,3-butadiene
copolymers, it being possible for these polymers also containing,
if required, one or more of the above-mentioned auxiliary
monomers.
[0016] The polymers are prepared by methods well known to those
skilled in the art, for example by emulsion polymerization or
suspension polymerization. The thus obtained initial polymer
dispersions preferably have a solids content of 30 to 70%. For the
preparation of the water-redispersible polymer powders, the aqueous
dispersions are preferably spray-dried, usually after the addition
of protective colloids as spraying assistants. Common additives
which may also be incorporated in the water-redispersible polymer
powders are anti-blocking agents.
[0017] In the production of synthetic fuel materials based on
solid, combustible materials, the common process steps are in
general as follows: The solid, combustible material is delivered to
a place where the reaction between the combustible material and the
polymer component takes place. Typically the solid, combustible
material is transported on a conveyor belt to the reaction region.
In the reaction section of the plant the polymer is added to the
combustible material in a manner to ensure the reaction between the
solid, combustible material and the polymer component. From the
reaction section the synthetic fuel thus produced is transported to
a place for storage or is directly transported to a combustion
section.
[0018] In general the solid, combustible material is reacted with
0.01 to 10% by weight, preferably 0.1 to 5% by weight of the
redispersible polymer powder, based on the weight of the solid
combustible material. The reaction between the solid, combustible
material and the redispersible polymer powder usually takes place
at a temperature between 5.degree. C. to 70.degree. C., preferably
15.degree. C. to 30.degree. C. Preferably the reaction takes place
under normal atmospheric pressure.
[0019] The present process can be designed as a dry process or a
wet process:
[0020] In a first embodiment of the dry process the redispersible
polymer powder composition is metered onto the combustible
material, preferably by dusting the powder onto the combustible
material on the conveyor belt. The mixture of combustible material
and redispersible polymer powder continues along the conveyor, and
in a preferred embodiment it is treated with water or steam.
Usually 0.1% by weight to 50% by weight, preferably 0.1% to 10%,
and most preferably 0.1% to 2% of water or steam are contacted with
the mixture of combustible material and polymer powder just before
entering a mill, the amounts by weight based on the weight of
combustible material. In each embodiment of the present process the
water is only needed to improve the contact between the combustible
material and the polymer. The amount of water also depends on the
moisture content of the combustible material. Therefore depending
on the glass transition temperature of the polymer and the moisture
of the combustible material, in general only very low amounts of
water need to be added, in contrast to prior art processes, where
the water is primarily needed to transport the polymer to the coal,
and therefore very high amounts are required. In this first
embodiment, the thus treated mixture of combustible material and
redispersible polymer powder continues along the conveyor and into
the mill where they are thoroughly mixed.
[0021] In a second embodiment the solid, combustible material is
also transported along the conveyor, and is treated with water or
steam in the above mentioned amounts. The redispersible polymer
powder is then metered onto the coal carrying conveyor just before
entering the mill, where the combustible material and polymer are
thoroughly mixed.
[0022] In a third embodiment of the dry process the redispersible
polymer powder composition is metered onto the combustible
material, preferably by dusting the powder onto the combustible
material on the conveyor belt. The mixture of combustible material
and redispersible polymer powder continues along the conveyor and
into the mill where mixing begins to take place. Within the mill,
water or steam in an amount as described above is introduced.
[0023] In a fourth embodiment the redispersible polymer powder
composition is metered onto the combustible material, preferably by
dusting the powder onto the combustible material on the conveyor
belt. The mixture of combustible material and redispersible polymer
powder continues along the conveyor and into the mill where they
are thoroughly mixed. When the material exits the mill, the
material passes a unit where it is treated with water or steam in
an amount as described above.
[0024] In a wet process design, the solid, combustible material
proceeds along the conveyor and is sprayed with an aqueous
redispersion of the redispersible polymer before entering the mill,
where the combustible material and polymer are thoroughly mixed.
The redispersion is prepared by admixing redispersible polymer
powder with water. In a further embodiment of the invention, the
solid, combustible material proceeds along the conveyor, and enters
the mill, wherein an aqueous redispersion of the redispersible
polymer is added. The mixture is thoroughly mixed in the mill. In
both these embodiments, organic diluents such as glycols,
glycerine, etc. are preferably absent.
[0025] In general the milling step is followed by a consolidation
step, such as briquetting.
[0026] The reaction between the solid, combustible material and the
polymer takes place substantially in the milling step at the above
defined conditions. The reaction is controlled by analytical
methods well-known for this purpose in the state of art. Preferred
are Fourier-transform infrared spectroscopy (FTIR) and the
thermogravimetric analysis (TGA). The procedures are known to those
skilled in the art, as indicated by U.S. Pat. No. 6,641,624, column
6, line 34 to column 8, line 60, herein incorporated by
reference.
[0027] The inventive process reduces the complexity of raw material
procurement logistics, because of the solid state of the polymer.
Flat-bed transport is more economical to the end user than liquid
bulk transport. At low temperatures, freezing generally destroys
aqueous polymer dispersions, but does not affect redispersible
polymer powders, thus not requiring the addition of diluent. The
dry process allows the customer to utilize less polymer based on
the fact that reaction kinetics are closely linked with proximity
of reactants. Using redispersible polymer powder, the extra step
required on current state of the art, i.e. diluting the aqueous
polymer emulsion, is removed. Above all, the amount of water used
in the process, which is detrimental to the end product, is
minimized in comparison to the state of the art.
EXAMPLES
[0028] In examples 1 to 3 a water-redispersible polymer powder
composition based on a vinyl acetate ethylene copolymer with a
glass transition temperature Tg of -7.degree. C. was used. In
examples 5 to 7 a water-redispersible polymer powder composition
based on a vinyl acetate homopolymer with a glass transition
temperature Tg of +30.degree. C. is used.
Example 1
[0029] 1000 g of coal fines are introduced into a blender and
dry-mixed with 10 g of water-redispersible polymer powder. The mix
is spread out onto a metal plate and uniformly sprayed with 100 ml
of water. Agglomeration of the coal fines occurs.
Example 2
[0030] 1000 g of coal fines are sprayed with steam until a weight
increase of 5% is measured. The wet coal fines are introduced into
a blender and mixed with 10 g of water-redispersible polymer
powder. Agglomeration of the coal fines occurs.
Example 3
[0031] 1000 g of coal fines is sprayed with 100 g of an aqueous
redispersion of the water-redispersible polymer powder with a
solids content of 50%. The wet coal fines are introduced into a
blender and mixed. Agglomeration of the coal fines occurs.
Comparison Example 4
[0032] 1000 g of coal fines are mixed with 10 kg of a polymer
dispersion based on a vinyl acetate ethylene copolymer
(Tg=-7.degree. C.) with a solids content of 50%. A dispersion with
a syrup-like consistency is obtained.
Example 5
[0033] The procedure of Example 1 is followed with the exception
that a water-redispersible polymer powder composition based on a
vinyl acetate homopolymer with a glass transition temperature Tg of
+30.degree. C. is used. Agglomeration of the coal fines occurs in
the same manner.
Example 6
[0034] The process of Example 2 is followed with the exception that
a water-redispersible polymer powder composition based on a vinyl
acetate homopolymer with a glass transition temperature Tg of
+30.degree. C. is used. Agglomeration of the coal fines occurs in
the same manner.
Example 7
[0035] The process of Example 3 is followed, on the exception that
a water-redispersible polymer powder composition based on a vinyl
acetate homopolymer with a glass transition temperature Tg of
+30.degree. C. was used. Agglomeration of the coal fines occurs in
the same manner.
[0036] The comparison between the examples and the comparison
example shows that in contrast to state of the art procedures, with
the inventive process a synthetic fuel in a solid state is
obtained, ready for combustion, without loss in heat energy owing
to the necessity to evaporate a high amounts of water.
[0037] In the context of the invention, and also in the claims,
where water or steam is specified, a mixture of water and steam may
of course be used. By the term "along a conveyor" or "on a
conveyor" is meant transport over a distance irrespective of the
actual construction of the conveying means. In most instances, a
conveying belt, either continuous or of links, etc., may be used.
However, other conveying means such as screw-type conveyors,
bucket-type conveyors, pneumatic tube conveyors, and like or
equivalent conveying means, i.e. any suitable means may be
used.
[0038] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *