TECHNICAL FIELD
The present invention relates to a coal for a boiler fuel, which is used for a
fuel for a coal-fired boiler.
BACKGROUND ART
5 For a coal-fired boiler, which uses a coal as a fuel for combustion, because
flue gas generated from the combustion of the coal contains sulfur oxide (SOx), the
flue gas is discharged after sulfur oxide is removed from the flue gas.
For example, Patent Document 1 described below proposes the removal of
sulfur oxide from flue gas as follows: super fine particles (1 to 100 nm) of calcium
10 oxide (CaO) are generated by laser irradiation heating or plasma heating of a
calcium compound such as calcium oxide (CaO), calcium carbonate (CaC03), or
calcium hydroxide (Ca(OH)2); the super fine particles are injected into the inside of
a furnace or the inside of a flue to react with sulfur oxide in the flue gas, thus the
sulfur oxide is removed from the flue gas.
15 CITATION LIST
Patent Literature(s)
Patent Document 1: Japanese Unexamined Patent Application Publication No.
H05-269341A
Patent Document 2: Japanese Unexamined Patent Application Publication No.
20 H0?-00461 OA
25
Patent Document 3: Japanese Unexamined Patent Application Publication No.
H09-126411 A
SUMMARY OF INVENTION
Technical Problem
However, in the method proposed in the Patent Document 1, because it was
necessary to install a laser ablation device, a high-frequency inductively coupled
plasma generating device, an arc-plasma generating device and the like in the boiler
device, the device cost became very high for a large-volume coal-fired boiler, and it
was not practical.
2
Therefore, it is a strong demand to enable simple generation of super fine
particles of calcium oxide at low cost.
Solution to Problem
The first invention to solve the problem described above is a coal for a boiler
5 fuel used as a fuel for a coal-fired boiler. The coal for a boiler fuel comprises a
reformed coal (ion-exchanged coal), the reformed coal comprising a raw coal and
Ca ion-exchanged coal. The raw coal comprises a lignite or a subbituminous coal
and the amount of calcium is not less than an equimolar amount relative to the
molar amount of sulfur in the raw coaL
10 The second invention is the coal for a boiler fuel according to the first
invention, in which the reformed coal further ion-exchanges iron. The amount
ratio of iron is in a range from 0.1 to 5 wt% relative to dry-weight of the raw coal.
The third invention is the coal for a boiler fuel according to the first or the
second invention, in which the reformed coal includes calcium ion exchanged on the
15 raw coal in a range from 4 to 10 wt% relative to dry-weight of the raw coal, and the
coal for a boiler fuel comprises a mixed coal which is a mixture of a basic coal
comprising at least one kind from a bituminous coal, a subbituminous coal and a
lignite and the reformed coal, and the amount ratio of the reformed coal is in a range
from 10 to 50 wt%.
20 The fourth invention is the coal for a boiler fuel according to any of the
inventions from the first to the third invention, in which the coal for a boiler fuel is
subjected to pyrolysis treatment.
The fifth invention is the coal for a boiler fuel according to the fourth
invention, in which the coal for a boiler fuel is further subjected to deactivation
25 treatment.
Advantageous Effects of Invention
A coal for a boiler fuel pertaining to the present invention enables the
presence of calcium oxide (CaO) as super fine particles (particle size: a few to a few
tens of nanometers) from a calcium (Ca) portion ion-exchanged on the coal through
30 combustion at high temperature, when the coal for a boiler fuel is injected and
supplied to a boiler furnace as a fuel and subjected to the combustion at high
3
5
temperature to become flue gas. Thus, the coal for a boiler fuel according to the
present invention facilitates the generation of super fine particles of calcium oxide
at low cost, and reduces the cost for the boiler device greatly.
Brief Description of Drawing(s)
FIG. 1 is a flow chart to illustrate manufacturing steps of the first
embodiment of a coal for a boiler fuel pertaining to the present invention.
FIG. 2 is a schematic view of a treatment device for ion-exchanging
treatment in FIG. 1.
FIG. 3 is a schematic view of a boiler device applied for the coal for a boiler
I 0 fuel obtained from the manufacturing steps in FIG. I.
15
FIG. 4 is a flow chart to illustrate manufacturing steps of the second
embodiment of a coal for a boiler fuel pertaining to the present invention.
FIG. 5 is a schematic view of a boiler device applied for the coal for a boiler
fuel obtained from the manufacturing steps in FIG. 4.
FIG. 6 is a flow chart to illustrate manufacturing steps of the third
embodiment of a coal for a boiler fuel pertaining to the present invention.
FIG. 7 is a schematic view of a boiler device applied for the coal for a boiler
fuel obtained from the manufacturing steps in FIG. 6.
FIG. 8 is a flow chart to illustrate a main portion of manufacturing steps of
20 the fourth embodiment of a coal for a boiler fuel pertaining to the present invention.
25
FIG. 9 is a schematic view of a treatment device for ion-exchanging
treatment in the other embodiments of the coal for a boiler fuel pertaining to the
present invention.
Description of Embodiments
Embodiments of the coal for a boiler fuel pertaining to the present invention
will be described based on the drawings, but the present invention is not limited
only to the following embodiments described based on the drawings.
4
First Embodiment
The first embodiment of the coal for a boiler fuel pertaining to the present
invention will be described based on FIGS. 1 to 3.
5 A coal for a boiler fuel pertaining to the present embodiment is a coal for a
boiler fuel used as a fuel for a coal-fired boiler. The coal for a boiler fuel
comprises a reformed coal, which includes a raw coal comprising a lignite or a
subbituminous coal, and calcium (Ca) ion-exchanged on the raw coal. The amount
of calcium is not less than an equimolar amount relative to the molar amount of
10 sulfur (S) in the raw coal.
The coal for a boiler fuel pertammg to the present embodiment can be
obtained easily as illustrated in FIGS. 1 and 2 as follows: water 1, the raw coal 2
(sulfur content 0.4 to 1.2 wt% (when dried)), the particle size (about 50 mm) of
which is adjusted by pulverization (to the maximum particle size about 5 mm), and
15 a calcium compound 3 such as calcium oxide (CaO), calcium carbonate (CaC03) or
calcium hydroxide (Ca(OH)2), are introduced into a treatment tank Ill of a
treatment device 110 and stirred with a stirring blade 112 (pH 8 to 12). Calcium
ion is eluted from the calcium compound 3 into the water 1 and contained in the
water 1. By the contact with the raw coal 2, the calcium ion undergoes ion
20 exchange with hydrogen ion of a hydroxy group ( -OH) or a carboxyl group
(-COOH) present on the raw coal 2. Thus, the calcium is ion-exchanged on the
raw coal 2 at the amount described above (S 11 in FIG. 1 ). This is followed by
separation such as filtration from the interior of the treatment tank 111 to the
exterior (S 12 in FIG. 1 ), and water washing treatment as necessary (S 13 in FIG. 1 ).
25 This is further followed by filtration treatment (S 14 in FIG. 1 ).
The coal for a boiler fuel (reformed coal) 10 manufactured as described
above is subjected to drying and pulverization (particle size: about 0.1 mm),
injected and supplied as a fuel into the inside of a boiler furnace 211 as illustrated in
FIG. 3, and subjected to combustion at high temperature (temperature: 1500 to
30 1700°C) to produce flue gas 6.
At this point, sulfur oxide (SOx) generated by the combustion at high
temperature from sulfur (S) portion contained in the coal for a boiler fuel 10 exists
5
in the flue gas 6. In addition, calcium oxide (CaO) generated from calcium (Ca)
portion ion-exchanged on the coal for a boiler fuel 10 exists as the super fine
particles (particle size: a few to a few tens of nanometers).
Then, sulfur oxide in the flue gas 6 can easily react with calcium oxide,
5 which has a very large specific surface area due to being super fine particles, to
produce calcium sulfate (CaS04).
The flue gas 6, sulfur oxide m which is converted to calcium sulfate, is
cooled by heat exchange at a heat exchanger 212, and a solid content 7 containing
the calcium sulfate and the like is removed by a particle removal device 213,
10 followed by venting from a stack 214 to the exterior.
In other words, conventionally, the super fine particles (1 to 100 nm) of
calcium oxide (CaO) are generated by laser irradiation heating or plasma heating of
a calcium compound such as calcium oxide (CaO), calcium carbonate (CaC03) or
calcium hydroxide (Ca(OH)2), and the super fine particles are injected into the
15 inside of the furnace or the inside of the flue to react with sulfur oxide (SOx) in the
flue gas. Thus, the sulfur oxide in the flue gas is removed. In the present
embodiment, calcium oxide (CaO) of super fine particles (a few to a few tens of
nanometers) are generated in the flue gas 6 by combustion at high temperature using
the coal for a boiler fuel (reformed coal) 10, in which calcium (Ca) is
20 ion-exchanged on the raw coal 2 at the amount described above, as a fuel for the
boiler furnace 211 and the super fine particles are reacted with sulfur oxide (SOx) in
the flue gas 6. Thus, the sulfur oxide in the flue gas 6 is removed.
Therefore, conventionally, it is necessary to install a laser ablation device, a
high-frequency inductively coupled plasma generating device, an arc-plasma
25 generating device and the like in the boiler device. In the present embodiment, not
only there is no need to install devices described above, but also there is no need to
install a desulfurization device in the boiler device.
Therefore, according to the coal for a boiler fuel 10 pertaining to the present
embodiment, it is possible to generate super fine particle (a few to a few tens of
30 nanometers) of calcium oxide (CaO) easily at low cost and to reduce the cost of the
boiler device greatly.
6
Meanwhile, it is necessary that the amount of calcium ion-exchanged on the
raw coal 2 is not less than the equimolar amount relative to the molar amount of
sulfur in the raw coal 2. This is because sulfur oxide generated by the combustion
may not be removed sufficiently if the amount of calcium ion-exchanged on the raw
5 coal 2 is less than the equimolar amount relative to the molar amount of sulfur in
the raw coal 2.
Also, though a lignite or a sub-bituminous coal can be used as the raw coal 2,
it is difficult to use a bituminous coal as the raw coal 2. This is because a lignite
or a sub-bituminous coal has a hydroxy group ( -OH), a carboxyl group ( -COOH)
10 and the like in the amount necessary to ion exchange with calcium ion and to
ion-exchange calcium, but a bituminous coal does not have enough groups
described above to ion-exchange calcium sufficiently.
Second Embodiment
The second embodiment of the coal for a boiler fuel pertaining to the present
15 invention will be described based on FIGS. 4 and 5. Note that, for parts that are
the same as the above embodiment, the same reference numerals as those used in the
description of the above embodiment are used, and therefore duplicate descriptions
of the above embodiment are omitted.
A coal for a boiler fuel pertaining to the present embodiment comprises the
20 reformed coal, in which the raw coal 2 ion-exchanges calcium (Ca) in an amount not
less than the equimolar amount relative to the molar amount of sulfur (S) in the raw
coal 2 and, in addition, further ion-exchanges iron (Fe) in a range from 0.1 to 5 wt%
relative to a dry-weight of the raw coal 2.
The coal for a boiler fuel pertaining to the present embodiment can be
25 obtained easily as illustrated in FIG. 4 as follows: water 1, the raw coal 2, the
calcium compound 3 and an iron compound 4 such as iron sulfate (FeS04) and the
like are introduced into the treatment tank 111 of the treatment device 11 0 and
stirred with the stirring blade 112 (pH 8 to 12), in the same manner as described in
the embodiment above. While calcium ion is eluted from the calcium compound 3
30 into the water 1 and contained in the water 1, iron ion is eluted from the iron
compound 4 into the water 1 and contained in the water 1. By the contact with the
raw coal 2, the calcium ion and the iron ion undergo ion exchange with hydrogen
ion of a hydroxy group ( -OH) or a carboxyl group ( -COOH) present on the raw coal
7
2. Thus, the calcium and the iron are ion-exchanged on the raw coal 2 at the
amount described above, respectively (S 11 in FIG. 4). This is followed by
separation such as filtration from the interior of the treatment tank Ill to the
exterior (Sl2 in FIG. 4), and water washing treatment optionally (Sl3 in FIG. 4).
5 This is further followed by filtration treatment (Sl4 in FIG. 4).
The coal for a boiler fuel (reformed coal) 20 manufactured as described
above is subjected to drying and pulverization (particle size: about 0.1 mm),
injected and supplied as a fuel into the inside of the boiler furnace 211 as illustrated
in FIG. 5, and subjected to combustion at high temperature (temperature: 1500 to
10 1700°C) to produce flue gas 6.
15
At this point, in addition to sulfur oxide (SOx) and calcium oxide present in
the flue gas 6 in the same manner as in the embodiment described above, iron oxide
(FeO) generated from iron (Fe) portion ion-exchanged on the coal for a boiler fuel
20 exists as super fine particles (particle size: a few to a few tens of nanometers).
Then, sulfur oxide in the flue gas 6 reacts with calcium oxide to produce
calcium sulfate (CaS04), as in the same manner as the embodiment described above.
On the other hand, iron oxide in the flue gas 6, which has a very large specific
surface area due to being super fine particles, contacts with carbon portion of the
coal for a boiler fuel 20 with very high probability to complete combustion
20 (oxidation) of the carbon portion by catalytic function.
The flue gas 6, in which sulfur oxide is converted to calcium sulfate while
carbon portion is com busted (oxidized) thoroughly, is cooled by heat exchange at
the heat exchanger 212. Then, a solid material 8 containing the calcium sulfate
and the like and little unburned carbon portion is removed from flue gas 6 at the
25 particle removal device 213 and the flue gas 6 is discharged from the stack 214 to
the exterior.
In other words, in the present embodiment, iron oxide (FeO) of super fine
particles (a few to a few tens of nanometers) in addition to calcium oxide (CaO) are
generated in the flue gas 6 by combustion at high temperature using the boiler fuel
30 (reformed coal) 20, in which not only calcium (Ca), but also iron (Fe) are
ion-exchanged on the raw coal 2, as a fuel in the boiler furnace 211. Thereby,
sulfur oxide is removed from the flue gas 6 as well as carbon portion is thoroughly
com busted (oxidized).
8
Therefore, the present embodiment can improve the combustion efficiency
inside the boiler furnace 211 compared with that of the embodiment described
above.
Therefore, according to the coal for a boiler fuel 20 of the present
5 embodiment, it is possible not only to gain the same effect as in the embodiment
described above, but also to produce less unburned carbon portion remained in the
solid material 8 that is collected in the particle removal device 213 than that of the
embodiment described above.
Meanwhile, the amount of iron ion-exchanged on the raw coal 2 is preferably
10 in a range from 0.1 to 5 wt% relative to the dry-weight of the raw coal 2. The
reasons are following: If the amount of iron ion-exchanged on the raw coal 2 is less
than 0.1 wt% relative to the dry-weight of the raw coal 2, the effect described above
does not manifest itself sufficiently. If the amount of iron ion-exchanged on the
raw coal 2 is more than 5 wt% relative to the dry-weight of the raw coal 2, it takes
15 too much time to perform the ion-exchanging treatment, as well as the improvement
of the combustion efficiency reaches the threshold.
Third embodiment
The third embodiment of the coal for a boiler fuel pertaining to the present
invention will be described based on FIGS. 6 and 7. Note that, for parts that are
20 the same as the above embodiment, the same reference numerals as those used in the
description of the above embodiment are used, and therefore. duplicate descriptions
of the above embodiment are omitted.
A coal for a boiler fuel pertaining to the present embodiment comprises a
mixed coal of the reformed coal and a basic coal and the amount ratio of the
25 reformed coal is in a range from 10 to 50 wt% in the mixed coal. In the reformed
coal, the raw coal 2 ion-exchanges calcium (Ca) in an amount in a range from 4 to
10 wt% relative to the dry-weight of the raw coal 2 (not less than the equimolar
amount relative to the molar amount of sulfur (S)), and, in addition, further
ion-exchanges iron (Fe) in a range from 0.1 to 5 wt% relative to the dry-weight of
30 the raw coal 2. The basic coal comprises at least one kind from a bituminous coal,
a subbituminous coal and a lignite.
9
The coal for a boiler fuel pertaining to the present embodiment can be
obtained easily as illustrated in FIG. 6 as follows: water 1, the raw coal 2, the
calcium compound 3 and an iron compound 4 such as iron sulfate (FeS04) and the
like are introduced into the treatment tank 111 of the treatment device 11 0 and
5 stirred with the stirring blade 112 (pH 8 to 12), in the same manner as described in
the embodiment above. While calcium ion is eluted from the calcium compound 3
into the water 1 and contained in the water 1, iron ion is eluted from the iron
compound 4 into the water 1 and contained in the water 1. By the contact with the
raw coal 2, the calcium ion and the iron ion undergo ion exchange with hydrogen
10 ion of a hydroxy group ( -OH) or a carboxyl group ( -COOH) present on the raw coal
2. Thus, the calcium and the iron are ion-exchanged on the raw coal 2 at the
amount described above, respectively (S 11 in FIG. 6). This is followed by
separation such as filtration from the interior of the treatment tank 111 to the
exterior (S 12 in FIG. 6), and water washing treatment optionally (S 13 in FIG. 6).
15 This is further followed by filtration treatment (S14 in FIG. 6). Then the reformed
coal 30 is obtained. The coal for a boiler fuel pertaining to the present
embodiment can be obtained easily by mixing treatment (S 15 in FIG. 6) of a basic
coal 5 comprising at least one kind from a bituminous coal, a subbituminous coal
and a lignite, and the reformed coal 30, so that the amount ratio of the reformed coal
20 30 is in a range from 10 to 50 wt%.
The coal for a boiler fuel (mixed coal) 40 manufactured as described above is
subjected to drying and pulverization (particle size: about 0.1 mm), then injected
and supplied as a fuel into the inside of a boiler furnace 211 as illustrated in FIG. 7,
and subjected to combustion at high temperature (temperature: 1500 to 1700°C) to
25 produce flue gas 6.
At this point, sulfur oxide (SOx) produced by the combustion at high
temperature from sulfur (S) portion contained in the coal for a boiler fuel 40 exists
in the flue gas 6. In addition, calcium oxide (CaO) generated from calcium (Ca)
portion and iron oxide (FeO) generated from iron (Fe) portion ion-exchanged on the
30 reformed coal 30 in the coal for a boiler fuel 40 exist as the super fine particles
(particle size: a few to a few tens of nanometers).
Then, calcium oxide in the flue gas 6 reacts with sulfur oxide (SOx)
generated from sulfur (S) portion contained in the reformed coal 30 and the basic
coal 5 to produce calcium sulfate (CaS04). In addition, iron oxide in the flue gas 6
10
contacts with carbon portion in the reformed coal 30 and the basic coal 5 at high
probability to combust (oxidize) the carbon portion thoroughly by the catalytic
function.
The flue gas 6, in which sulfur oxide is converted to calcium sulfate while
5 carbon portion is com busted (oxidized) thoroughly, is cooled by heat exchange at
the heat exchanger 212 in the same manner as in the embodiment described above.
Then, the solid material 8 is removed from flue gas 6 at the particle removal device
213 and the flue gas 6 is discharged from the stack 214 to exterior.
In other words, in the present embodiment, calcium in the molar amount not
10 less than the sum of the molar amount of sulfur portion in the raw coal 2 and the
molar amount of sulfur portion in the basic coal 5 is ion-exchanged on the raw coal
2. Thereby, sulfur oxide generated from the sulfur portion of the basic coal 5,
which does not ion-exchange calcium, can be converted to calcium sulfate and
removed from the flue gas 6.
15 Therefore, in the present embodiment, the basic coal 5, which does not
ion-exchange calcium can be supplied as a fuel in the boiler furnace 211, and it is
possible to reduce the usage amount of the reformed coal 30, which can be obtained
by ion-exchanging treatment of calcium on the raw coal 2.
Therefore, according to the coal for a boiler fuel 40 of the present
20 embodiment, it is possible not only to gain the same effect as in the embodiment
described above, but also to produce the coal for a boiler fuel more efficiently than
the embodiment described above and to reduce the cost of manufacturing.
Meanwhile, the ratio of the reformed coal 30 in the boiler fuel (mixed coal)
40 is preferably in a range from 10 to 50 wt%. In other words, the ratio of the
25 basic coal 5 in the boiler fuel (mixed coal) 40 is preferably in a range from 50 to 90
wt%. The reasons are following: If the ratio of the basic coal 5 in the boiler fuel
(mixed coal) 40 is less than 50 wt%, it is difficult to improve manufacturing
efficiency of the coal for a boiler fuel 40 greatly. If the ratio of the basic coal 5 in
the boiler fuel (mixed coal) 40 is more than 90 wt%, it may not be possible to
30 convert sulfur oxide generated from the sulfur portion of the basic coal 5 to calcium
sulfate sufficiently.
11
Meanwhile, the amount of calcium ion-exchanged on the raw coal 2 is
preferably in a range from 4 to 10 wt% relative to the dry-weight of the raw coal 2.
The reasons are following: If the amount of calcium ion-exchanged on the raw coal
2 is less than 4 wt% relative to the dry-weight of the raw coal 2, it may not be
5 possible to convert sulfur oxide generated from the sulfur portion of the basic coal 5
to calcium sulfate sufficiently, depending on the characteristics of the basic coal 5
or the mix ratio with the basic coal 5. If the amount of calcium ion-exchanged on
the raw coal 2 is more than 10 wt% relative to the dry-weight of the raw coal 2, it
takes too much time to perform the ion-exchanging treatment (S 11) on the raw coal
10 2, which brings about the reduction in manufacturing efficiency, and it may become
difficult to reduce manufacturing cost.
Fourth embodiment
The fourth embodiment of the coal for a boiler fuel pertaining to the present
invention will be described based on FIG. 8. Note that, for parts that are the same
15 as the above embodiment, the same reference numerals as those used in the
description of the above embodiment are used, and therefore duplicate descriptions
of the above embodiment are omitted.
The coal for a boiler fuel pertaining to the present embodiment is the mixed
coal 40 subjected to pyrolysis treatment and, in addition, deactivation treatment.
20 The coal for a boiler fuel pertaining to the present embodiment is easily
obtained as follows: As illustrated in FIG. 8, the mixed coal 40 obtained by the same
manner as in the third embodiment described above is placed in the drying device
then heated and dried (about 100°C) and water component is removed (S21 in FIG.
8). This is followed by transfer to the inside of the pyrolysis device and heating
25 and pyrolysis (about 400°C) in inert gas atmosphere such as nitrogen gas is
performed to remove volatile components including mercury (Hg) and the like (S22
in FIG. 8). This pyrolyzed coal is transferred to the inside of the cooling device to
be cooled (about 50°C) (S23 in FIG.8), then transferred to the inside of the
deactivation treatment device. Then the activated surface is subjected to
30 deactivation treatment in the atmosphere for the deactivation (oxygen
concentration: a few to 21 volume %) (S24 in FIG. 8), followed by shaping to a
particulate shape in the briquetting device (S25 in FIG. 8).
12
In other words, the coal for a boiler fuel 50 pertaining to the present
embodiment is obtained by subjecting the boiler fuel (mixed coal) 40 further to the
pyrolysis treatment and, in addition, to the deactivation treatment.
Therefore, because most part of the volatile components such as mercury is
5 removed beforehand for the coal for a boiler fuel 50 pertaining to the present
embodiment, mercury content in the flue gas 6 can be greatly reduced and
suppressed down to not more than the exhaust regulation concentration when the
coal for a boiler fuel 50 is supplied and combusted as a fuel in the boiler furnace
211.
10 Therefore, not only that the same effects as in the case of the embodiments
described above can be obtained, but also that the mercury content in the flue gas 6
can be greatly reduced for the coal for a boiler fuel 50 pertaining to the present
embodiment. Thereby, there is no need to install a mercury removal device in the
boiler device, and the cost for the boiler device can be further reduced.
15
Meanwhile, as the calcium compound 3, not only particles, particulate bodies
and the like such as calcium oxide (CaO), calcium carbonate (CaC03), or calcium
hydroxide (Ca(OH)2) can be used, but also, waste materials containing calcium such
as, for example, gypsum waste, cement waste, seashells, flyash, and iron and steel
20 slag can be used.
Particularly, it is very preferable that calcium sulfate in the solid materials 7
or 8 collected at the particle removal device 213 is used as the calcium compound 3,
because the source of calcium can be recycled and the generation of the waste can
be greatly suppressed. Similarly, it is very preferable that iron sulfate in the solid
25 materials 8 collected at the particle removal device 213 is used as the iron
compound 4, because the source of iron can be recycled and the generation of the
waste can be greatly suppressed.
When the waste materials described above are used as the calcium compound
3, it is very preferable to perform the following: As illustrated in FIG. 9, for
30 example, while water 1 and the raw coal 2 are introduced into the treatment tank Ill
of a treatment device 210 and stirred by a stirring blade 112, water 1 and the
calcium compound 3 are introduced into the elution tank 213 and stirred by the
13
stirring blade 214. Thereby, calcium ion is eluted from the calcium compound 3
and contained in the water 1 in the elution tank 213. While the water 1 is fed to
the inside of the treatment tank 111 from the elution tank 213 through the filter 213a,
the same amount of water 1 fed into the inside of the treatment tank 111 is returned
5 to the inside of the elution tank 213 from the treatment tank 111 through the filter
111 a. Thereby, calcium can be ion-exchanged on the raw coal 2 without the
calcium compound 3 (waste material) coexisting with the raw coal 2 and the
calcium compound 3 (waster material) and the raw coal 2 can be easily separated.
At this time, if calcium ion is not easily eluted from the calcium compound 3
10 (waste material) and water 1 does not easily exhibit pH 8 to 12, a pH adjusting
agent (e.g. calcium hydroxide, calcium carbonate and the like) 9 can be added to the
inside of the treatment tank 111 to adjust the pH of the water 1 to pH 8 to 12.
In the third and fourth embodiments described above, the mixed coal (the
coal for a boiler fuel) 40 that is a mixture of the reformed coal 30, in which calcium
15 and iron are ion-exchanged on the raw coal 2, and the basic coal 5, is explained.
20
However, as the other embodiment, for example, the mixed coal (the coal for a
boiler fuel) that is a mixture of the reformed coal, in which calcium is
ion-exchanged, but iron is not ion-exchanged, on the raw coal 2, and the basic coal
5, can be used in the same manner as in the embodiments described above.
In the fourth embodiment described above, the coal for a boiler fuel 50 is
manufactured as follows: The mixed coal (the coal for a boiler fuel) 40 is heated
and dried in the drying device, and transferred to the inside of the pyrolysis device
and heated and pyrolyzed; Then, the pyrolyzed coal is transferred to the inside of
the cooling device and cooled, transferred to the inside of the deactivation treatment
25 device and subjected to the deactivation treatment, then shaped to a particulate
shape in the briquetting device. However, as the other embodiment, for example,
the coal for a boiler fuel 50 can be manufactured as follows: The reformed coal 30
and the basic coal 5 are introduced into the drying device while mixing, and heated
and dried, then transferred to the inside of the pyrolysis device and dried and
30 pyrolyzed. Then, the pyrolyzed coal is transferred to the inside of the cooling
device and cooled, transferred to the inside of the deactivation treatment device and
subjected to the deactivation treatment, then shaped to the particulate shape in the
briquetting device.
14
Also, in the fourth embodiment described above, it is described that the coal
for a boiler fuel 50 is manufactured by subjecting the mixed coal (the coal for a
boiler fuel) 40, which is a mixture of the reformed coal 30 and the basic coal 5, to
the pyrolysis treatment and the deactivation treatment. However, as the other
5 embodiment, it is possible to obtain the coal for a boiler fuel by subjecting the
reformed coal 10 or 20, which is obtained in the first or the second embodiment
described above, to the pyrolysis treatment and the deactivation treatment, for
example.
Also, in the fourth embodiment described above, it is described that the coal
10 for a boiler fuel 50 is manufactured by subjecting the coal for a boiler fuel 40 to
pyrolysis treatment and deactivation treatment. However, as the other
embodiment, it is possible to omit the deactivation treatment if the coal for a boiler
fuel is used as a boiler fuel in a relatively short term after the pyrolysis treatment
without long-distance transportation, for example.
15 As described above, the coal for a boiler fuel pertaining to the present
invention can be realized, by combining the optional technical aspects described in
the individual embodiments described above.
EXAMPLES
The following verification tests were performed to verify the effects of the
20 coal for a boiler fuel pertaining to the present invention.
Preparation of test substances
Test substance A
A reformed coal (15 wt% ), in which a raw coal compnsmg a lignite
ion-exchanging calcium (8 wt%), and a basic coal (85 wt%) comprising a lignite
25 were introduced in a dryer to be heated and dried while being mixed, then were
transferred to the inside of a pyrolysis device to be heated and pyrolyzed.
Subsequently, the pyrolyzed coal was transferred into the inside of a cooling device
to be cooled, transferred into the inside of a deactivation treatment device to be
subjected to deactivation treatment and shaped to a particulate shape in a
30 briquetting device. Thus, the coal for a boiler fuel (Test substance A) was
obtained.
15
Test substance B
A reformed coal (15 wt% ), in which a raw coal comprising a lignite
ion-exchanging iron (2 wt%) as well as ion-exchanging calcium (6 wt%), and a
basic coal (85 wt%) comprising a lignite were introduced in a dryer to be heated and.
5 dried while being mixed, then were transferred to the inside of a pyrolysis device to
be heated and pyrolyzed. Subsequently, the pyrolyzed coal was transferred into
the inside of a cooling device to be cooled, transferred into the inside of a
deactivation treatment device to be subjected to deactivation treatment and shaped
in a briquetting device to be a particulate shape. Thus, the coal for a boiler fuel
10 (Test substance B) was obtained.
Comparative substance
A basic coal (1 00 wt%) comprising a lignite was introduced in a dryer to be
heated and dried while being mixed, then was transferred to the inside of a pyrolysis
device to be heated and pyrolyzed. Subsequently, the pyrolyzed coal was
15 transferred into the inside of a cooling device to be cooled, transferred into the
inside of a deactivation treatment device to be subjected to deactivation treatment
and shaped in a briquetting device to be a particulate shape. Thus, the coal for a
boiler fuel (Comparative substance) was obtained.
20
Test method
The test substances A and B described above and the comparative substance
described above were each injected into the inside of a boiler furnace and
combusted at high temperature as a fuel. The concentration of sulfur dioxide in
the flue gas generated and the ratio of unburned carbon in the solid material
collected were obtained separately.
25 Test results
The test results are shown in Table 1 below.
[Table 1]
so2 concentration (ppm) Ratio of unburned carbon (wt%)
Test substance A 90 2.3
16
test substance B 95 0.5
Comparative 980 3.5
substance
As shown in Table 1 above, for the comparative substance (Ca and Fe were
not ion-exchanged), the concentration of sulfur dioxide greatly exceeded the
reference value (1 ,000 ppm) in the exhausted gas, and the ratio of unburned carbon
5 in the solid material collected was relatively large.
In contrast, for the test substance A (ion-exchanging Ca only) and the test
substance B (ion-exchanging both Ca and Fe), it was confirmed that the
concentration of sulfur dioxide in the flue gas can be made less than the reference
value (1 00 ppm). Furthermore, for the test substance B, it was confirmed that the
10 ratio of unburned carbon in the solid material collected can be made very small.
Industrial Applicability
A coal for a boiler fuel according to the present invention facilitates the
generation of super fine particles of calcium oxide at low cost, and reduces the cost
15 for the boiler device greatly. Therefore, it can be utilized very beneficially in the
industry.
Reference Signs List
1 Water
20 2 Raw coal
3 Calcium compound
4 Iron compound
5 Basic coal
6 Waste gas
17
7, 8 Solids
9: pH-adjusting agent
10, 20 Reformed coal (coal for a boiler fuel)
3 0 Reformed coal
5 40 Mixed coal (coal for a boiler fuel)
50 Coal for a boiler fuel
110, 120 Treatment device
111 Treatment tank
lila Filter
10 112 Stirring blade
123 Elution tank
123a Filter
124 Stirring blade
211 Boiler furnace
15 212 Heat exchanger
213 Particle removal device
214 Stack
18

CLAIMS
1. A coal for a boiler fuel used as a fuel for a coal-fired boiler, the coal for a boiler
fuel comprising a reformed coal, the reformed coal comprising a raw coal and
calcium ion-exchanged on the raw coal, the raw coal comprising a lignite or a
sub-bituminous coal, and an amount of the calcium being not less than an
equimolar amount relative to a molar amount of sulfur in the raw coal.
2. The coal for a boiler fuel according to claim 1, wherein the reformed coal further
ion-exchanges iron, and an amount ratio of the iron being in a range from 0.1 to
5 wt% relative to a dry-weight of the raw coal.
3. The coal for a boiler fuel according to claim 1 or 2, wherein the reformed coal
includes ion-exchanged calcium in a range from 4 to 10 wt% relative to a
dry-weight of the raw coal, and the coal for a boiler fuel comprises a mixed coal,
the mixed coal being a mixture of a basic coal and the reformed coal, the basic
coal comprising at least one kind from a bituminous coal, a subbituminous coal
and a lignite, and an amount ratio ofthe reformed coal is in a range from 10 to 50
wt%.
4. The coal for a boiler fuel according to any one of claims 1 to 3, wherein the coal
for a boiler fuel is treated with pyrolysis treatment.
5. The coal for a boiler fuel according to claim 4, wherein the coal for a boiler fuel
is further treated with deactivation treatment.