Note: Descriptions are shown in the official language in which they were submitted.
CA 02898724 2015-07-20
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DESCRIPTION
Title of the Invention
METHOD FOR PRODUCING RESIDUE COAL
Technical Field
[0001]
The present invention relates to a method for producing a by-product coal
which is yielded as a by-product when an ashless coal is obtained through
removal of
ash components from coal.
Background Art
[0002]
A method for producing an ashless coal is disclosed in Patent Document 1. In
such a production method, a raw material coal as a mixture of steam coal and
caking
coal is mixed with a solvent to prepare a slurry, and the slurry thus prepared
is heated,
thereby extracting coal components soluble in the solvent, then the
gravitational settling
method is applied to the slurry in which the coal components has been
extracted,
thereby separating the slurry into a solution which contains the coal
components soluble
in the solvent and a solid-content concentrated liquid containing coal
components
insoluble in the solvent, and further the removal of the solvent from the
separated
solution is carried out, thereby obtaining an ashless coal.
Prior Art Document
Patent Documents
[0003]
Patent Document 1: JP-A-2009-227718
Summary of the Invention
Problem that the Invention is to Solve
[0004]
1
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4
In the process for producing an ashless coal, a by-product coal is yielded as
a
by-product in addition to an ashless coal as the final product.
[0005]
The by-product coal is obtained through the evaporative separation of a
solvent
from a solid-content concentrated liquid. In the process, a by-product coal
mixture
containing the by-product coal in which the solvent remains is obtained first
through the
evaporative separation of the solvent from the solid-content concentrated
liquid, and
then the by-product coal is obtained through the evaporative separation of the
remaining
solvent from the by-product coal mixture.
[0006]
In the case of intending to obtain a by-product coal through the drying of a
large quantity of by-product coal mixture, however, there arises a problem
that there is
no drying means which allows the temperature of the by-product coal mixture to
be
increased to temperatures equal to or higher than the boiling temperature of
the solvent
(about 240 C). The steam temperature of a steam tube dryer as an example of
drying
means is 220 C at the highest, and hence prolongation of a residence time
becomes
necessary, which results in a cost increase.
[0007]
An object of the present invention is therefore to provide a method for
producing a by-product coal, which allows a reduction in cost for drying a by-
product
coal mixture through the simplification of a device for drying the by-product
coal
mixture.
Means for Solving the Problem
[0008]
A method for producing a by-product coal according to the present invention
comprises: an extraction step of heating a slurry prepared by mixing a coal
and a
solvent, thereby extracting a coal component soluble in the solvent; a
separation step of
separating the slurry which has been obtained in the extraction step into a
solution in
which the coal component soluble in the solvent is dissolved and a solid-
content
concentrated liquid in which a coal component insoluble in the solvent is
concentrated;
and a by-product coal acquirement step of evaporating and separating the
solvent from
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the solid-content concentrated liquid which has been separated in the
separation step,
thereby acquiring a by-product coal; wherein the by-product coal acquirement
step
comprises: a by-product coal mixture acquirement step of evaporating and
separating
the solvent from the solid-content concentrated liquid which has been
separated in the
separation step, thereby acquiring a by-product coal mixture containing a by-
product
coal in which the solvent remains; and a by-product coal drying step of
evaporating and
separating the remaining solvent from the by-product coal mixture, thereby
acquiring
the by-product coal, wherein, in the by-product coal drying step, the solvent
remaining
in the by-product coal mixture is evaporated and separated by exploiting heat
that the
by-product coal mixture itself has.
Advantageous Effects of the Invention
[0009]
According to the method for producing a by-product coal in the present
invention, the device for drying a by-product coal mixture is simplified, and
thus, the
cost for drying the by-product coal mixture can be reduced.
Brief Description of the Drawings
[0010]
FIG. 1 is a schematic diagram of an ashless coal production equipment.
FIG. 2 is a graph showing evaluation results based on drying time.
Embodiments for Carrying Out the Invention
[0011]
In the following, an exemplary embodiment for carrying out the present
invention is illustrated in detail by reference to the drawings.
[0012]
(Method for Producing Ashless Coal)
The method of producing a by-product coal in accordance with an exemplary
embodiment in the present invention is carried out in ashless-coal production
equipment
100 to be used for a method of producing an ashless coal. As shown in FIG. 1,
the
ashless-coal production equipment 100 includes, in the order from the upstream
side of
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, .
,
the production process of an ashless coal (HPC), a coal hopper 1, a solvent
tank 2, a
slurry preparation tank 3, a transport pump 4, a preheater 5, an extraction
tank 6, a
gravitational settling tank 7, a filter unit 8, solvent separators 9 and 10,
and a dryer 11.
[0013]
The method of producing an ashless coal includes a slurry preparation step, an
extraction step, a separation step, an ashless coal acquirement step and a by-
product
coal acquirement step. Of these steps, the slurry preparation step, the
extraction step,
the separation step and the by-product coal acquirement step are included in
the method
for producing a by-product coal in accordance with the present embodiment.
Each of
these steps is explained below. Additionally, a coal to be used as a raw
material in the
present production method has no particular restriction, and bituminous coal
high in
extraction rate may be used or a low rank coal low in price (such as
subbituminous coal
or brown coal) may be used. Herein, the term "ashless coal" refers to a coal
having an
ash content of 5 wt% or less, preferably 3 wt% or less.
[0014]
(Slurry Preparation Step)
The slurry preparation step is a step of preparing a slurry by mixing a coal
and
a solvent. This slurry preparation step is performed in the slurry preparation
tank 3 in
FIG. 1. The coal as a raw material is added to the slurry preparation tank 3
from the
coal hopper 1, and simultaneously, a solvent is added to the slurry
preparation tank 3
from the solvent tank 2. The coal and solvent which are added to the slurry
preparation tank 3 are mixed by the stirrer 3a, thereby forming into a slurry
composed
of the coal and the solvent.
[0015]
The mixing proportion of the coals to the solvent is e.g. from 10 to 50 wt%,
preferably from 20 to 35 wt%, on a dried coal basis.
[0016]
(Extraction Step)
The extraction step is a step of extracting coal components soluble in the
solvent (a step of dissolving such components in the solvent) by heating the
slurry
obtained in the slurry preparation step. This extraction step is performed in
the
preheater 5 and the extraction tank 6 in FIG. 1. The slurry which has been
prepared in
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the slurry preparation tank 3 is fed to the preheater 5 by means of the
transport pump 4,
heated up to a predetermined temperature, then fed to the extraction tank 6,
and further
kept at a predetermined temperature while stirring by the stirrer 6a. In this
way, the
extraction is performed.
[0017]
In a case of extracting coal components soluble in the solvent by heating the
slurry prepared by mixing the coal with the solvent, a solvent in which the
coal is highly
soluble, more specifically an aromatic solvent (a hydrogen donative solvent or
a
hydrogen nondonative solvent) in many cases, is mixed with a coal, and by
heating the
resulting mixture, organic components in the coal are extracted.
[0018]
The hydrogen nondonative solvent is a coal-derived solvent obtained mainly by
refining carbonization products of coal and predominantly composed of bicyclic
aromatic compounds. Because such a hydrogen nondonative solvent is stable even
under conditions of heating and has a high affinity for coal, the proportion
of soluble
components (coal components) extracted with the solvent (hereafter referred to
as the
extraction rate, too) is high, and the solvent can be easily recovered by the
methods such
as distillation. Main ingredients in the hydrogen nondonative solvent are
bicyclic
aromatic compounds such as naphthalene, methylnaphthalene, dimethylnaphthalene
or
trimethylnaphthalene. As the other ingredients in the hydrogen nondonative
solvent,
examples thereof include a naphthalene, a anthracene and a fluorine, which
each have
aliphatic side chains, and further include biphenyl and an alkylbenzene having
long-
chain aliphatic side chains.
[0019]
Although the case of using a hydrogen nondonative compound as the solvent
is described in the above explanation, it goes without saying that any of
hydrogen
donative compounds (including the case of coal liquefied oil), typified by
tetralin, can
be used as the solvent. The use of a hydrogen donative solvent brings about
enhancement of ashless coal yield.
[0020]
Additionally, the solvent has no particular restriction as to its boiling
temperature. From the viewpoints of pressure reductions in the extraction step
and
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separation step, an extraction rate in the extraction step, a solvent recovery
rate in the
ashless coal acquirement step and the like, solvents having boiling
temperatures in a
range of 180 C to 300 C, especially 240 C to 280 C, can be used favorably. In
the
present embodiment, the boiling temperature of the solvent is about 240 C.
[0021]
The heating temperature of the slurry in the extraction step has no particular
limitations so long as dissolution of solvent-soluble components can be
achieved.
From the viewpoint of ensuring thorough dissolution of solvent-soluble
components and
improvement in extraction rate, the heating temperature is e.g. from 300 C to
420 C,
preferably 360 C to 400 C. In the present embodiment, the slurry is heated by
the
preheater 5, and thereby, as mentioned later, the temperature of a solid-
content
concentrated liquid to be fed to a solvent separator 10 is adjusted so that a
by-product
coal mixture to be fed to a dryer 11 has a calorific value allowing the
remaining solvent
to be evaporated and separated from the by-product coal mixture.
[0022]
The heating time (extraction time) also has no particular limitations, but
from
the viewpoint of ensuring thorough dissolution and improvement in extraction
rate, the
heating time is e.g. from 10 to 60 minutes. Herein, the term "heating time"
refers to
the sum of the heating time in the preheater 5 in FIG. 1 and the heating time
in the
extraction tank 6 in FIG. 1.
[0023]
The extraction step is carried out in the presence of an inert gas such as
nitrogen. The suitable pressure inside the extraction tank 6 is e.g. from 1.0
to 2.0 MPa,
though it depends on the temperature during the extraction and the vapor
pressure of a
solvent to be used. When the pressure inside the extraction tank 6 is lower
than the
vapor pressure of the solvent, the solvent vaporizes and the solvent cannot be
confined
within the liquid phase, and the extraction ends in failure. In order to
confine the
solvent within the liquid phase, pressure higher than the vapor pressure of
the solvent is
therefore necessary. On the other hand, when the pressure is too high, it
brings about
increases in costs of equipment and operation, and it is therefore
uneconomical.
[0024]
(Separation Step)
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The separation step is a step of separating the slurry which has been obtained
in
the extraction step into a solution in which coal components soluble in the
solvent are
dissolved and a solid-content concentrated liquid (solvent-insoluble component
concentrated liquid) which contains coal components insoluble in the solvent
(solvent-
insoluble components such as ash components) in a concentrated state, by the
gravitational settling method. This separation step is carried out in the
gravitational
settling tank 7 in FIG. 1. In the gravitational settling tank 7, the slurry
which has been
obtained in the extraction step is separated into supernatant liquor as the
solution and
the solid-content concentrated liquid by dint of gravity. The supernatant
liquor in the
upper part of the gravitational settling tank 7 is discharged into the solvent
separator 9,
if necessary, by way of the filter unit 8, and simultaneously, the solid-
content
concentrated liquid settled in the lower part of the gravitational settling
tank 7 is
discharged into the solvent separator 10.
[0025]
The gravitational settling method is a method of holding the slurry in the
tank,
and settling and separating the solvent-insoluble components by exploiting
gravity.
The solvent-insoluble components (e.g. ash components) having a specific
gravity
larger than that of the solution in which coal components soluble in the
solvent are
dissolved, settle in the lower part of the gravitational settling tank 7 by
the force of
gravity. By continuously discharging the supernatant liquor from the upper
part of the
tank and the solid-content concentrated liquid from the lower part of the tank
while
continuously feeding the slurry into the tank, continuous separation treatment
becomes
possible.
[0026]
For prevention of reprecipitation of solvent-soluble components eluted from
the coal, it is appropriate that the inside of the gravitational settling tank
7 be kept warm
(or in a heated state) or be left pressurized. The warming (heating)
temperature is e.g.
from 300 C to 380 C, and the pressure inside the tank is e.g. from 1.0 MPa to
3.0 MPa.
[0027]
In addition to the gravitational settling method, examples of methods for
separating the solution which contains coal components dissolved in the
solvent from
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the slurry which has been obtained in the extraction step include a filtration
method, a
centrifugal separation method and the like.
[0028]
(Ashless Coal Acquirement Step)
The ashless coal acquirement step is a step of acquiring an ashless coal (HPC)
through the evaporative separation of the solvent from the solution
(supernatant liquor)
which has been separated in the separation step. This ashless coal acquirement
step is
carried out in the solvent separator 9 in FIG. 1. After the filtration in the
filter unit 8,
the solution which has been separated in the gravitational settling tank 7 is
fed to the
solvent separator 9, and in the solvent separator 9, the solvent is evaporated
and
separated from the supernatant liquor. The evaporative separation of the
solvent from
the solution is preferably carried out in the presence of an inert gas such as
nitrogen.
In the present embodiment, the solvent is evaporated and separated from the
solution in
an atmosphere of nitrogen gas introduced into the solvent separator 9.
[0029]
As the method for separating the solvent from the solution (supernatant
liquor),
a common distillation or evaporation method or the like can be used. The
solvent
which has been separated in the solvent separator 9 is returned to the solvent
tank 2, and
is used in cycles. Circulating use of the solvent is preferable, but not
essential (which
is also applicable to the by-product coal acquirement step mentioned later).
By
separating the solvent from the supernatant liquor, an ashless coal (HPC)
containing
substantially no ash components can be obtained.
[0030]
The ashless coal contains almost no ash components, is absolutely free of
moisture, and offers a calorific value higher than a raw material coal. In
addition, the
ashless coal has an extensive improvement in coal plastic properties
(flowability) which
are especially important for a raw material of steelmaking coke, and even when
the raw
material coal has no plastic properties, the ashless coal (HPC) obtained from
it has
excellent plastic properties. Accordingly, the ashless coal can be used e.g.
in a coal
blend as a raw material for making coke. Further, the ashless coal almost free
of ash
components has high combustion efficiency and can reduce the amount of ashes
produced. Attention is therefore being given to the use of ashless coal as a
gas turbine
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direct-injection fuel in a high-efficiency, combined-cycle generation system
utilizing
gas turbine combustion.
[0031]
(By-product Coal Acquirement Step)
The by-product coal acquirement step is a step of evaporating and separating
the solvent from the solid-content concentrated liquid which has been
separated in the
separation step, thereby acquiring a by-product coal. This by-product coal
acquirement step includes a by-product coal mixture acquirement step and a by-
product
coal drying step.
[0032]
(By-product Coal Mixture Acquirement Step)
The by-product coal mixture acquirement step is a step of evaporating and
separating the solvent from the solid-content concentrated liquid which has
been
separated in the separation step, thereby acquiring a by-product coal mixture
containing
a by-product coal in which the solvent remains. This by-product coal mixture
acquirement step is carried out in the solvent separator 10 in FIG. 1. The
solid-content
concentrated liquid which has been separated by the gravitational settling
tank 7 is fed
to the solvent separator 10, and the solvent is evaporated and separated from
the solid-
content concentrated liquid in the solvent separator 10. The evaporative
separation of
the solvent from the solid-content concentrated liquid is preferably performed
in the
presence of an inert gas such as nitrogen. In the present embodiment, the
solvent
separator 10 is a flash distillation tank to be used in a flash distillation
method. The
flash distillation method is a method of spraying a solid-content concentrated
liquid into
a tank inside of which has been in an atmosphere of nitrogen gas, thereby
evaporating
and separating the solvent.
[0033]
The method for separating the solvent from the solid-content concentrated
liquid is not limited to the flash distillation method, and a common
distillation or
evaporation method can be applicable thereto as in the case of the ashless
coal
acquirement step. The solvent which has been separated in the solvent
separator 10 is
returned to the solvent tank 2, and is used in cycles. By separating the
solvent from
the solid-content concentrated liquid, a by-product coal mixture containing
the by-
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product coal in which the solvent remains in a proportion of 5 to 10 wt% can
be
obtained.
[0034]
The solid-content concentrated liquid which has been separated by the
gravitational settling tank 7 has been in a high-temperature high-pressure
condition
which does not allow the solvent to be evaporated and separated. By spraying
the
solid-content concentrated liquid which has been in such a condition into the
solvent
separator 10 the inside of which is held at normal pressure, the pressure on
the solid-
content concentrated liquid is released. Thus, the boiling temperature of the
solvent is
lowered, and the solvent is evaporated and separated at a dash from the high-
temperature solid-content concentrated liquid. At this time, the temperature
of the
solid-content concentrated liquid to be fed to the solvent separator 10 has
been adjusted
so that the by-product coal mixture to be fed to the dryer 11 at a later time
has a
calorific value allowing the remaining solvent to be evaporated and separated
from the
by-product coal mixture. This temperature adjustment is carried out, as
mentioned
above, by means of the preheater 5 for heating the slurry which has been
prepared in the
slurry preparation tank 3. This temperature adjustment may be carried out by
heating
the solid-content concentrated liquid which has been separated by the
gravitational
settling tank 7 but before feeding into the solvent separator 10.
Alternatively, this
temperature adjustment may be carried out by heating both the slurry which has
been
prepared in the slurry preparation tank 3 and the solid-content concentrated
liquid which
has been separated by the gravitational settling tank 7.
[0035]
(By-product Coal Drying Step)
The by-product coal drying step is a step of evaporating and separating the
remaining solvent from the by-product coal mixture, thereby acquiring the by-
product
coal. This by-product coal drying step is carried out in the dryer 11 in FIG.
1. The
by-product coal mixture which has been obtained in the solvent separator 10 is
fed to
the dryer 11 and the remaining solvent is evaporated and separated from the by-
product
coal mixture in the dryer 11. The evaporative separation of the solvent from
the by-
product coal mixture is preferably carried out in the presence of an inert gas
such as
nitrogen. In the present embodiment, the dryer 11 is a rotary dryer which
holds therein
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the by-product coal mixture and carries out stirring while circulating therein
a nitrogen
gas as carrier gas. By separating the remaining solvent from the by-product
coal
mixture, it becomes possible to obtain the by-product coal (RC, also referred
to as
residual coal) in which solvent-insoluble components including ash components
have
been concentrated.
[0036]
The by-product coal contains absolutely no moisture though it contains ash
components, and has a sufficient calorific value. The by-product coal shows no
coal
plastic properties, and when used in a coal blend, it does not impair the coal
plastic
properties of other kinds of coals included in the coal blend because it has
been
subjected to elimination of oxygen-containing functional groups. Thus, this by-
product coal can be used as a portion of the coal blend for coke-making
material as in
the case of usual non- or slightly-caking coals, and may also be used for
various kinds
of fuels without being used as a coke-making material.
[0037]
In the present embodiment, the remaining solvent is evaporated and separated
from the by-product coal mixture in the dryer 11 by exploiting the heat that
the by-
product coal mixture itself, which is the mixture including the by-product
coal and
solvent, has. More specifically, in the dryer 11, the by-product coal mixture
is only
retained and stirred, and any heat is not given to the by-product coal
mixture. The
expression that "the heat that the by-product coal mixture itself has" means
the heat
borne (possessed) by the by-product coal mixture obtained through the
separation of the
solvent from the solid-content concentrated liquid, and does not mean the heat
generated from the by-product coal mixture through chemical reaction. Since
the by-
product coal mixture itself has heat, the by-product coal mixture has a given
calorific
value. The calorific value that the by-product coal mixture has is a value
allowing the
remaining solvent to be evaporated and separated from the by-product coal
mixture.
When a main ingredient of the solvent is methylnaphthalene, the calorific
value required
for evaporating and separating the solvent in a unit amount is 330 kJ/kg (the
calorific
value required for evaporation of 1 kg of the solvent). As mentioned above, by
adjusting the temperature of the solid-content concentrated liquid fed to the
solvent
11
. = , CA 02898724 2015-07-20
separator 10, the by-product coal mixture fed to the dryer 11 is adjusted so
as to have
such a calorific value.
[0038]
In order to dry powder, it generally becomes necessary to use a device for
applying heat to the powder. However, the by-product coal mixture itself,
which is
obtained in the by-product coal mixture acquirement step (the solvent
separator 10), has
a considerable amount of heat. Thus, by evaporating and separating the
remaining
solvent from the by-product coal mixture by exploiting the heat that the by-
product coal
mixture itself has, necessity for applying heat to the by-product coal mixture
is
eliminated. With this being the situation, a device for drying the by-product
coal
mixture can be simplified, and costs for drying the by-product coal mixture
can be
reduced.
[0039]
In addition, by adjusting the temperature of the solid-content concentrated
liquid fed to the by-product coal mixture acquirement step (the solvent
separator 10),
the by-product coal mixture fed to the by-product coal drying step (the dryer
11) is
adjusted so as to have a calorific value allowing the remaining solvent to be
evaporated
and separated from the by-product coal mixture. In general the application of
heat to
liquid is greater in efficiency than the case where heat is applied to solid.
The
temperature adjustment of the solid-content concentrated liquid in a liquid
state is
therefore easier than that of the by-product coal mixture in a somewhat
solidified state.
Thus, the temperature adjustment is not given to the by-product coal mixture
fed to the
by-product coal drying step (the dryer 11), but the temperature adjustment is
given to
the solid-content concentrated liquid fed to the by-product coal mixture
acquirement
step (the solvent separator 10). Thereby, it becomes possible to appropriately
provide
the by-product coal mixture with a calorific value allowing the remaining
solvent to be
evaporated and separated from the by-product coal mixture.
[0040]
Further, the temperature of the solid-content concentrated liquid fed to the
by-
product coal mixture acquirement step (the solvent separator 10) is adjusted
by heating
at least one of the slurry prepared in the slurry preparation tank 3 and the
solid-content
concentrated liquid separated by the gravitational settling tank 7. Because
the slurry
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= CA 02898724 2015-07-20
and the solid-content concentrated liquid are liquids, heat can be applied to
them with
efficiency. Thus, by heating the slurry or the solid-content concentrated
liquid, the
temperature of the solid-content concentrated liquid fed to the by-product
coal mixture
acquirement step can be adjusted appropriately.
[0041]
(Drying Time Evaluation)
Next, the time required to dry the by-product coal was evaluated at each of
different drying temperatures. For making such evaluations, a tube furnace was
used.
In a procedure for each evaluation, first of all, the temperature was raised
so that the
temperature inside the furnace reached a predetermined drying temperature
while
circulating a nitrogen gas through the furnace. Then, a by-product coal
mixture
containing 28 wt% of the solvent, as a sample, was put in the furnace in a
condition that
the sample was placed on a porcelain dish fitted with a thermocouple.
Thereafter,
drying time measurement was started at the time when the temperature of the
sample
reached the predetermined drying temperature. The sample was taken out after
the
passage of a predetermined time, and examined on the solvent content therein.
In
accordance with this procedure, the evaluation is performed under each of
different
drying temperatures of 210 C, 250 C and 270 C. Evaluation results obtained
are
shown in FIG. 2.
[0042]
As to the times required to reduce the solvent content in the sample to 2 wt%
under different drying temperatures, they were about 30 minutes under the
drying
temperature of 210 C, about 15 minutes under the drying temperature of 250 C
and
about 10 minutes under the drying temperature of 270 C. These results show
that, as
compared the case of the drying temperature of 210 C corresponding to the
steam
temperature of a steam tube dryer, the time required for drying under the
temperature of
250 C can be cut in about one-half. In addition, it is also shown that the
time required
for drying under the temperature of 270 C can be reduced to about one-third as
compared with the case under the drying temperature of 210 C.
[0043]
(Effects)
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As mentioned above, according to the method of producing a by-product coal
according to the present embodiment, the remaining solvent is evaporated and
separated
from the by-product coal mixture by exploiting heat that the by-product coal
mixture
itself has, in the by-product coal drying step (the dryer 11). In general, a
device for
applying heat to powder becomes necessary for the powder to be dried. However,
the
by-product coal mixture itself, which is obtained in the by-product coal
mixture
acquirement step (the solvent separator 10), has a considerable amount of
heat. Thus,
by evaporating and separating the remaining solvent from the by-product coal
mixture
by exploiting the heat that the by-product coal mixture itself has, necessity
for applying
heat to the by-product coal mixture is eliminated. By doing so, a device for
drying the
by-product coal mixture can be simplified, and costs for drying the by-product
coal
mixture can be reduced.
[0044]
In addition, by adjusting the temperature of the solid-content concentrated
liquid fed to the by-product coal mixture acquirement step (the solvent
separator 10),
the by-product coal mixture fed to the by-product coal drying step (the dryer
11) is
adjusted so as to have a calorific value allowing the remaining solvent to be
evaporated
and separated from the by-product coal mixture. In general, the application of
heat to
liquid is greater in efficiency the case where heat is applied to solid.
Therefore, the
temperature adjustment of the solid-content concentrated liquid in a liquid
state is easier
than that of the by-product coal mixture in a somewhat solidified state. Thus,
the
temperature adjustment is not given to the by-product coal mixture fed to the
by-product
coal drying step, but the temperature adjustment is given to the solid-content
concentrated liquid fed to the by-product coal mixture acquirement step. By
doing so,
it becomes possible to appropriately provide the by-product coal mixture with
a
calorific value allowing the remaining solvent to be evaporated and separated
from the
by-product coal mixture.
[0045]
Further, the temperature of the solid-content concentrated liquid fed to the
by-
product coal mixture acquirement step (the solvent separator 10) is adjusted
by heating
at least one of the slurry and the solid-content concentrated liquid. Because
the slurry
and the solid-content concentrated liquid are liquids, heat can be applied to
them with
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efficiency. Thus, by heating the slurry or the solid-content concentrated
liquid, the
temperature of the solid-content concentrated liquid fed to the by-product
coal mixture
acquirement step can be adjusted appropriately.
[0046]
Furthermore, in the by-product coal mixture acquirement step (the solvent
separator 10), the solid-content concentrated liquid which has been in a high-
temperature
high-pressure condition, which does not allow the solvent to be evaporated and
separated,
is sprayed into a tank the inside of which is kept at normal pressure, and
then, the
pressure on the solid-content concentrated liquid is released. Thus, the
boiling
temperature of the solvent is lowered, and the solvent is evaporated and
separated at a
dash from the high-temperature solid-content concentrated liquid. With this
being the
situation, the solvent can be appropriately evaporated and separated from the
solid-
content concentrated liquid.
[0047]
(Modification Examples of Present Embodiment)
Although an exemplary embodiment in the present invention has been described
in the foregoing, it merely exemplifies the concrete example and should not be
construed
as particularly limiting the present invention. The concrete configuration and
on the like
can be modified as appropriate. Further, the actions and effects described in
the
embodiment in the present invention are merely recited as the most appropriate
actions
and effects produced by the present invention, and actions and effects which
can be
achieved by the present invention should not be construed as being limited to
those
described in the exemplary embodiment in the present invention.
Industrial applicability
[0049]
CA 02898724 2015-07-20
=
The method for producing a by-product coal in the present invention allows
simplification of a device for drying a by-product coal mixture and the
reduction of
costs for drying.
Description of Reference Numbers
[0050]
1: Coal hopper
2: Solvent tank
3: Slurry preparation tank
3a: Stirrer
4: Transport pump
5: Preheater
6: Extraction tank
6a: Stirrer
7: Gravitational settling tank
8: Filter unit
9, 10: Solvent separator
11: Dryer
100: Ashless coal production equipment
16
