U.S. patent application number 13/437039 was filed with the patent office on 2012-10-11 for coal water slurry and methods for making the coal water slurry.
Invention is credited to Xijing Bi, Wei Chen, Lishun Hu, Shiguang Li, Wenhua Li, Dejia Wang, Mingmin Wang, Junli Xue.
Application Number | 20120255221 13/437039 |
Document ID | / |
Family ID | 45937044 |
Filed Date | 2012-10-11 |
United States Patent
Application |
20120255221 |
Kind Code |
A1 |
Wang; Mingmin ; et
al. |
October 11, 2012 |
COAL WATER SLURRY AND METHODS FOR MAKING THE COAL WATER SLURRY
Abstract
A coal water slurry comprises smaller and larger coal particles.
The smaller coal particles are in a range of from about 20 wt % to
about 90 wt % of the coal in the coal water slurry and comprise a
mean particle size smaller than 25 .mu.m. The larger coal particles
are in a range of from about 10 wt % to about 80 wt % of the coal
in the coal water slurry and comprise a mean particle size in a
range of from 50 .mu.m to 200 .mu.m.
Inventors: |
Wang; Mingmin; (Shanghai,
CN) ; Xue; Junli; (Shanghai, CN) ; Wang;
Dejia; (Shanghai, CN) ; Li; Shiguang;
(Shanghai, CN) ; Hu; Lishun; (Shanghai, CN)
; Bi; Xijing; (Shanghai, CN) ; Li; Wenhua;
(Shanghai, CN) ; Chen; Wei; (Shanghai,
CN) |
Family ID: |
45937044 |
Appl. No.: |
13/437039 |
Filed: |
April 2, 2012 |
Current U.S.
Class: |
44/280 |
Current CPC
Class: |
C10L 1/326 20130101 |
Class at
Publication: |
44/280 |
International
Class: |
C10L 5/00 20060101
C10L005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 7, 2011 |
CN |
201110085720.9 |
Claims
1. A coal water slurry, comprising: smaller coal particles in a
range of from about 20 wt % to about 90 wt % of the coal in the
coal water slurry and having a mean particle size smaller than 26
.mu.m; and larger coal particles in a range of from about 10 wt %
to about 80 wt % of the coal in the coal water slurry and having a
mean particle size in a range of from 50 .mu.m to 200 .mu.m.
2. The coal water slurry of claim 1, wherein the smaller and larger
coal particles comprise low rank coal.
3. The coal water slurry of claim 1, wherein the coal water slurry
comprises the smaller coal particles in a range of from about 40 wt
% to about 90 wt % and the larger coal particles in a range of from
about 10 wt % to about 60 wt % of the coal in the coal water
slurry, respectively.
4. The coal water slurry of claim 1, wherein the coal water slurry
comprises the smaller coal particles in a range of from about 50 wt
% to about 75 wt % and the larger coal particles in a range of from
about 25 wt % to about 50 wt % of the coal in the coal water
slurry, respectively.
5. The coal water slurry of claim 1, wherein the coal water slurry
comprises the smaller coal particles in a range of from about 30 wt
% to about 50 wt % and the larger coal particles in a range of from
about 50 wt % to about 70 wt % of the coal in the coal water
slurry, respectively.
6. The coal water slurry of claim 1, wherein the larger coal
particles have the mean particle size in a range of from about 50
.mu.m to about 140 .mu.m.
7. The coal water slurry of claim 1, wherein the large coal
particles have a mean particle size in a range of from 90 .mu.m to
140 .mu.m.
8. The coal water slurry of claim 1, wherein the large coal
particles have a mean particle size in a range of from 100 .mu.m to
140 .mu.m.
9. The coal water slurry of claim 1, wherein the large coal
particles have a mean particle size in a range of from 140 .mu.m to
200 .mu.m.
10. The coal water slurry of claim 1, wherein the smaller coal
particles have the mean particle size less than about 25 .mu.m.
11. The coal water slurry of claim 1, wherein the smaller coal
particles have the mean particle size less than about 15 .mu.m.
12. The coal water slurry of claim 1, wherein the smaller coal
particles have the mean particle size less than about 10 .mu.m.
13. The coal water slurry of claim 1, wherein the smaller coal
particles have the mean particle size in a range of from about 10
.mu.m to about 15 .mu.m.
14. A method for making a coal water slurry, comprising: milling
smaller coal particles in a range of from about 20 wt % to about 90
wt % of the coal in the coal water slurry and comprising a mean
particle size smaller than 26 .mu.m; milling larger coal particles
in a range of from about 10 wt % to about 80 wt % of the coal in
the coal water slurry and having a mean particle size in a range of
from 50 .mu.m to 200 .mu.m; and mixing the smaller coal particles,
the larger coal particles, and water.
15. The method for making the coal water slurry of claim 14,
further comprising filtering the coal water slurry after mixing of
the smaller coal particles and the larger coal particles.
16. The method for making the coal water slurry of claim 14,
wherein milling comprises using a coarse mill for producing the
larger coal particles and a fine mill for producing the smaller
coal particles.
17. The method for making the coal water slurry of claim 16,
wherein using the coarse mill comprises wet milling and using the
fine mill comprises dry milling.
18. The method for making the coal water slurry of claim 17,
wherein mixing comprises introducing the smaller coal particles and
the larger coal particles respectively into a mixing vessel.
19. The method for making the coal water slurry of claim 17,
wherein mixing comprises introducing the smaller coal particles
into the coarse mill for mixing.
20. The method for making the coal water slurry of claim 16,
wherein using the coarse mill comprises wet milling and using the
fine mill comprises wet milling.
21. The method for making the coal water slurry of claim 20,
further comprising introducing a portion of a coarse coal from the
coarse mill into a mixing vessel and another portion of the coarse
coal into the fine mill to produce the smaller coal particles for
introduction into the mixing vessel.
22. The method for making the coal water slurry of claim 14,
wherein the large coal particles have a mean particle size in a
range of from about 100 .mu.m to about 140 .mu.m.
23. The method for making the coal water slurry of claim 14,
wherein the mean particle size of the smaller coal particles is
less than about 25 um.
24. The method for making the coal water slurry of claim 14,
wherein the smaller coal particles are in a range of from about 50
wt % to about 75 wt % and the larger coal particles are in a range
of from about 25 wt % to about 50 wt % of the coal in the coal
water slurry, respectively.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] Embodiments of the invention relate generally to coal water
slurry and methods for making the coal water slurry. More
particularly, embodiments of the invention relate to particle size
distribution of coal in coal water slurry and methods for making
the coal water slurry.
[0003] 2. Description of Related Art
[0004] In coal gasification fields, two types of methods are
usually employed to supply coal to a gasifier for gasification. One
is pneumatically transporting pulverized coal with pressurized
nitrogen and spraying the coal into a gasifier. Another is
preparing a slurry of coal and water, which hereinafter is referred
to as "coal water slurry," and supplying the coal water slurry to a
gasifier. The "coal water slurry" method has been widely used
because it is more reliable, easy transportable and adaptable to a
higher gasification pressure than the method employing coal in a
dry state.
[0005] Generally, higher coal concentration of a coal water slurry
leads to higher gasification efficiency and lower consumption of
coal and oxygen. Thus, during preparation, it is desirable to have
higher concentration of the coal so as to economically gasify the
coal water slurry.
[0006] There have been attempts to increase the coal concentration.
For example, particle size distribution of coal in the coal water
slurry may be modified to increase the coal concentration. However,
in some current applications, the coal concentration may not be as
high as desirable and may cause undesirable viscosity in the coal
water slurry with the increase of the coal concentration in the
water slurry concentration by modification of the coal particle
size distribution.
[0007] Therefore, there is a need for new and improved coal water
slurry and methods for making the coal water slurry to increase the
coal concentration and avoid undesirable viscosity.
BRIEF SUMMARY OF THE INVENTION
[0008] A coal water slurry is provided in accordance with one
embodiment of the invention. The coal water slurry comprises
smaller and larger coal particles. The smaller coal particles are
in a range of from about 20 wt % to about 90 wt % of the coal in
the coal water slurry and comprise a mean particle size smaller
than 26 .mu.m. The larger coal particles are in a range of from
about 10 wt % to about 80 wt % of the coal in the coal water slurry
and comprise a mean particle size in a range of from 50 .mu.m to
200 .mu.m.
[0009] A method for making a coal water slurry is provided in
accordance with another embodiment of the invention. The method
comprises milling smaller coal particles in a range of from about
20 wt % to about 90 wt % of the coal in the coal water slurry and
comprising a mean particle size smaller than 26 .mu.m, milling
larger coal particles in a range of from about 10 wt % to about 80
wt % of the coal in the coal water slurry and comprising a mean
particle size in a range of from 50 .mu.m to 200 .mu.m, and mixing
the smaller coal particles, the larger coal particles, and
water.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0010] The above and other aspects, features, and advantages of the
present disclosure will become more apparent in light of the
following detailed description when taken in conjunction with the
accompanying drawings in which:
[0011] FIG. 1 is a schematic diagram of a coal particle size
distribution in a coal water slurry in accordance with one
embodiment of the invention;
[0012] FIG. 2 is an experimental diagram illustrating comparison of
correlations of coal concentration and viscosity with and without
smaller coal particles in the coal water slurry; and
[0013] FIGS. 3-6 are schematic flow charts illustrating preparation
of the coal water slurry in accordance with various embodiments of
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Preferred embodiments of the present disclosure will be
described hereinbelow with reference to the accompanying drawings.
In the following description, well-known functions or constructions
are not described in detail to avoid obscuring the disclosure in
unnecessary detail.
[0015] FIG. 1 illustrates a schematic diagram of a particle size
distribution of coal for producing a coal water slurry in
accordance with one embodiment of the invention. As used herein,
the term "coal water slurry" may indicate a mixture of certain
amounts of coal, water and additives for producing energy used in
generating electricity, heating, support processing, and
manufacturing. In recent years, use of coal water slurry has become
an alternative to use of conventional fuel oil and coal.
[0016] Typically, a coal water slurry may comprise from about 55 wt
% to about 70 wt % of coal particles, from about 30 wt % to about
45 wt % of water, and less than about 1 wt % of additives. It
should be noted that embodiments of the invention do not limit to
any particular type of coal or additives for the coal water slurry.
Non-limiting examples of additives include alkylnaphthelene
sulfonate and polyoxyalkylene alkyl ether.
[0017] Generally, it is desirable to increase the coal
concentration in the coal water slurry so as to improve
gasification efficiency and reduce consumption of coal and oxygen.
Higher coal concentration may be produced by pulverizing coal into
a suitable particle size distribution while selecting suitable
additives and appropriately mixing the coal, water and additives to
manufacture the coal water slurry with suitable concentration,
viscosity, stability, and quality. In embodiments of the invention,
the coal particle size distribution in the coal water slurry may be
selected so that smaller coal particles are dispersed into spaces
between larger coal particles so as to increase the coal
concentration in the coal water slurry.
[0018] As illustrated in FIG. 1, the particle size distribution of
the coal 10 for producing the coal water slurry may comprise
smaller coal particles 12 in a range of from about 20 wt % to about
90 wt % of a weight of the coal 10 and having a mean particle size
smaller than about 26 .mu.m, and larger coal particles 11 in a
range of from about 10 wt % to about 80 wt % of the weight of the
coal 10 and having a mean particle size in a range of from about 50
.mu.m to about 200 .mu.m. In some applications, the particle size
distribution of the coal may comprise the small coal particles 12
in a range of from about 30 wt % to about 90 wt % and the larger
coal particles 11 in a range of from about 10 wt % to about 70 wt %
of the weight of the coal 10, respectively. As used herein, wt %
means a weight percentage.
[0019] In other applications, the particle size distribution of the
coal 10 may comprise the small coal particles 12 in a range of from
about 40 wt % to about 90 wt % and the larger coal particles 11 in
a range of from about 10 wt % to about 60 wt % of the weight of the
coal 10, respectively. In certain applications, the particle size
distribution of the coal 10 may comprise the small coal particles
12 in a range of from about 50 wt % to about 75 wt % and the larger
coal particles 11 in a range of from about 25 wt % to about 50 wt %
of the weight of the coal 10, respectively.
[0020] Additionally, in some examples, the smaller coal particles
12 may have a mean particle size smaller than about 25 .mu.m, about
20 .mu.m, or about 15 .mu.m. In other examples, the smaller coal
particles 12 may have a mean particle size smaller than about 10
.mu.m or about 5 .mu.m. In certain examples, the smaller coal
particles 12 may have a mean in a range of from about 5 .mu.m to
about 15 .mu.m. Alternatively, the smaller coal particles 12 may
have a mean in a range of from about 10 .mu.m to about 15 .mu.m, or
from 5 .mu.m to about 10 .mu.m. The larger coal particles 11 may
have a mean particle size in a range of from about 50 .mu.m to
about 70 .mu.m, from about 70 .mu.m to about 140 .mu.m, from about
90 .mu.m to about 140 .mu.m, from about 100 .mu.m to about 140
.mu.m, or from about 140 .mu.m to about 200 .mu.m.
[0021] Accordingly, after mixing, the smaller coal particles may be
dispersed between the larger coal particles so as to increase the
coal concentration of the coal water slurry to be produced. In some
embodiments, the coal may comprise one or more of high rank coal,
such as bituminous and anthracite, and low rank coal, such as
sub-bituminous coal and lignite. In some examples, the coal
particle distribution may comprise a mixture of the smaller low
rank coal particles and the larger high rank coal particles, or the
smaller high rank coal particles and the larger low rank coal
particles. In one non-limiting example, both types of coal
particles comprise low rank coal, such as the sub-bituminous coal
and the lignite. Since the cost of low rank coal is lower, it may
be cost-effective in some examples to produce the coal water slurry
having higher coal concentration using the low rank coal.
[0022] Table-1 illustrates an experimental example of the coal
particle size distribution for producing a coal water slurry in
accordance with one embodiment. In this example, the coal comprises
a low rank coal.
TABLE-US-00001 TABLE 1 Coal particle size distribution Mesh
Particle size (.mu.m) Weight percentage (wt %) >8 >2500 0
8-14 1400-2500 3 14-40 850-1400 12 40-325 45-850 60 325-540 26-45
12.5 <540 <26 50
[0023] As can be seen from Table-1, the coal comprises about 50 wt
% of the smaller coal particles and about 50 wt % of the larger
coal particles. Particle sizes of the smaller coal particles are
less than 26 .mu.m, and particle sizes of the larger coal particles
in the range of from about 26 .mu.m to about 2500 .mu.m. For the
embodiments of the invention, the smaller coal particles have a
mean particle size smaller than 26 .mu.m. The larger coal particles
have a mean particle size in a range of from about 50 .mu.m to
about 200 .mu.m based on distribution of the weight percentages and
the particle sizes thereof, as mentioned above.
[0024] FIG. 2 is an experimental diagram illustrating comparison of
correlations of the coal concentration in the coal water slurry and
viscosity with and without the smaller coal particles in the coal
particle size distribution in accordance with one embodiment. As
illustrated in FIG. 2, lines 13-14 illustrate the correlations of
the coal water slurry concentration and the viscosity without and
with the smaller coal particles, respectively.
[0025] As can be seen from the line 13, at a point 15, in the
initiation of production of the coal water slurry, the coal
concentration in the coal water slurry is less than 46%. With the
amount of the coal increasing, the coal concentration reaches about
50% at a point 16 where the viscosity there of is less than 600 cp.
However, during preparation of the coal water slurry without the
smaller coal particles, the flowability of the coal water slurry
becomes worse at the point 16 such that it becomes disadvantageous
to increase the coal concentration further in the coal water
slurry.
[0026] For the line 14, under the similar operating conditions as
those for the line 13, in the initiation, at a point 17, since the
smaller coal particles are mixed with the larger coal particles,
the coal concentration in the coal water slurry reaches about 54%.
With the amount of the mixed coal increasing, the coal
concentration reaches above 56% at a point 18 where the viscosity
thereof exceeds 1400 cp. Then, a certain amount of the additives
may be added to decrease the viscosity of the coal water slurry to
about 1300 cp at a point 19, which is suitable for the flowability
of the coal water slurry.
[0027] Accordingly, for the comparison of the lines 13-14
illustrated in FIG. 2, the coal water slurry having the mixture of
the smaller coal particles and the larger coal particles may have
the higher coal concentration and higher flowability than the coal
water slurry without mixture of the smaller coal particles.
[0028] FIGS. 3-6 illustrate schematic flow charts illustrating
preparation of the coal water slurry in accordance with various
embodiments of the invention. As illustrated in FIG. 3, during
preparation, according to a determined proportion of the smaller
coal particles and the larger coal particles, certain amounts of
starting coals 20, 21 are introduced into a coarse mill 22 and a
fine mill 23 for milling, respectively.
[0029] It should be noted that in some applications, one or more
coarse mills 22 and one or more fine mills 23 may be employed
although one coarse mill 22 and one fine mill 23 are illustrated in
FIG. 3. The particle sizes of the starting coals 20, 21 may be less
than 3 mm. Although two starting coals 20, 21 are illustrated in
FIG. 3, one or more starting coal supply sources (not shown) may be
employed to provide one or more starting coals 20, 21.
[0030] For the illustrated arrangement in FIG. 3, the coarse mill
22 is for wet milling of the starting coal 20 and the fine mill 23
is for dry milling of the starting coal 21. In non-limiting
examples, the coarse mill 22 and the fine mill 23 may comprise ball
mills, and the particle sizes of the starting coals 20, 21 may be
different and not less than 3 mm. In certain applications, either
or both of the starting coals 20, 21 may comprise one or two of the
low rank coal and the high rank coal, and the starting coals 20, 21
may be the same or different from each other. In one non-limiting
example, the starting coals 20, 21 are the same low rank coal.
[0031] Accordingly, after the starting coals 20, 21 are introduced
into the coarse mill 22 and the fine mill 23, respectively,
according to determined particle size distribution of the smaller
and larger coal particles, the fine mill 23 mills the starting coal
21 to produce the dry smaller coal particles having a mean particle
size less than about 26 .mu.m. Meanwhile, with introduction of the
starting coal 20 into the coarse mill 22, determined amounts of
water 24 and additives 25 are also introduced into the coarse mill
22 to produce a coarse coal water slurry comprising the large coal
particles having a mean particle size in the range of from about 50
.mu.m to about 200 .mu.m.
[0032] Subsequently, the dry smaller coal particles from the fine
mill 23 and the coarse coal water slurry from the coarse mill 22
are introduced into a mixing vessel 26 for mixing to produce the
coal water slurry with higher concentration for further processing,
for example, for introduction into a gasifier 27 to produce energy.
For some arrangements, during mixing, a mixer (not shown) may be
employed to mix the dry smaller coal particles and the coarse coal
water slurry within the mixing vessel 26, and feed rates of the dry
smaller coal particles may be controlled into the mixing vessel 26
so as to ensure the water in the coarse coal water slurry to
contact with the smaller coal particles and the smaller coal
particles to disperse between the larger coal particles.
[0033] In certain applications, as illustrated in FIG. 3, before
the coal water slurry with higher coal concentration is introduced
into the gasifier 27 for processing, a filter 28 may be employed to
receive and filter the coal water slurry from the mixing vessel 26
to remove impurities, such as rock in the coal water slurry, which
is advantageous for processing of the coal water slurry in a
gasifier. Alternatively, the filter 28 may not be employed.
[0034] FIG. 4 illustrates a schematic flow chart of the preparation
of the coal water slurry in accordance with another embodiment of
the invention. The arrangement in FIG. 4 differs from the
arrangement in FIG. 3 in that the mixing vessel 26 in FIG. 3 is not
employed in the arrangement in FIG. 4. For the arrangement in FIG.
4, the dry smaller coal particles from the fine mill 23 are
introduced into the coarse mill 22 to mix with the larger coal
particles, water and the additives while the starting coal 20 is
milled in the coarse mill 22. In certain applications, a mixing
vessel may also be employed behind the coarse mill 22. Again, a
filter 28 may optionally be used before the coal water slurry is
sent to the gasifier 27.
[0035] FIG. 5 illustrates a schematic flow chart of the preparation
of the coal water slurry in accordance with yet another embodiment
of the invention. In the arrangement in FIG. 5, during preparation
of the smaller coal particles in the fine mill 23, certain amounts
of water 29 and optionally additives 30 are also introduced into
the fine mill 23 while the starting coal 21 is milled in the fine
mill 23 to mix with the smaller coal particles. In some
applications, one or more water supply sources and one or more
additive supply sources may be employed to provide the water 24, 29
and the additives 25, 30 respectively. The water 24, 29 and the
additives 25, 30 may be the same or different from each other. In
some applications, the additives 25 and/or 30 may only be
introduced into one of the mills or may be introduced into the
mixing vessel 26.
[0036] In the arrangement of FIG. 6, all of the starting coal 31 is
introduced into the coarse mill 22 for wet milling. During milling,
a certain amount of a coarse coal 32 from the coarse mill 22 is
introduced into the mixing vessel 26, which acts as the larger coal
particles, and another amount of the coarse coal from the coarse
mill 22 flows into the fine mill 23 for further wet milling to
produce the smaller coal particles. Then, the smaller coal
particles are mixed with the larger coal particles from the coarse
mill 22 in the mixing vessel 26 to produce the coal water slurry
with higher concentration. In certain applications, certain amounts
of water and additives may be added into either of the mills or
into the mixing vessel.
[0037] In embodiments of the invention, from about 20 wt % to about
90 wt % of the smaller coal particles 12 having a mean particle
size smaller than 25 um may be mixed with from about 10 wt % to
about 80 wt % of larger coal particles 11 having a mean particle
size in the range of from about 50 .mu.m to about 140 .mu.m so as
to produce the coal water slurry with higher coal concentration. In
some applications, low rank coal may be used to produce the coal
particle size distribution so as to produce the coal water slurry
with higher coal concentration, which is cost effective. In
addition, during preparation of the coal water slurry, wet milling
and/or dry milling may be employed so as to improve system
flexibility to produce the coal water slurry.
[0038] While the disclosure has been illustrated and described in
typical embodiments, it is not intended to be limited to the
details shown, since various modifications and substitutions can be
made without departing in any way from the spirit of the present
disclosure. As such, further modifications and equivalents of the
disclosure herein disclosed may occur to persons skilled in the art
using no more than routine experimentation, and all such
modifications and equivalents are believed to be within the spirit
and scope of the disclosure as defined by the following claims.
* * * * *