DESCRIPTION
FUEL TREATMENT SYSTEM, METHOD FOR UTILIZING OF EXHAUST
GAS, AND APPARATUS FOR UTILIZING OF EXHAUST GAS
Technical Field
[0001]
The present invention relates to a fuel treatment system,
a method for utilizing of exhaust gas, and an apparatus for
utilizing of exhaust gas.
Background Art
[0002]
Wi th the global increase of energy demand, it is
increasingly necessary to use, as fuel used in a thermal power
15 facility, low-grade fuel such as low-grade coal having a high
moisture content and biomass having high moisture content.
It is expected that such a tendency will further increase.
The low-grade coal, biomass and the like may hereinafter be
collectively referred to as low-grade fuel.
20 [0003]
The use of the low-grade fuel contributes to, however,
lower fuel consumption rate of the thermal power facility.
Particularly, in a coal using facility using pulverized coal,
the coal is dried and crushed for combustion and then
25 introduced into a combustion furnace. Therefore, increase
of the moisture amount in the coal used as fuel directly leads
to deterioration of the fuel consumption rate. In addi tion,
under an influence of a drying/crushing ability of a mill or
the like, it is necessary to limit an amount of such the
30 low-grade fuel used therein.
[0004]
In order to avoid such a situation, a method of drying
coal and a drying facility disclosed in Unexamined Japanese
Patent Application Publication No. JP 10-281443 A (Patent
35 Document 1) listed below are known, for example. The drying
facility in Patent Document 1 dries high-moisture coal as
2
low-grade fuel in an atmosphere of BO°C to 150°C using
combustion exhaust gas after passing through an exhaust gas
temperature reduction device such as an air heater.
[0005]
5 Meanwhile, in a coal-fired thermal power facility,
generation of electricity is performed in a generator by
combusting fuel such as pulver i zed coal or heavy oi 1,
petroleum coke, in a combustion furnace such as a boiler to
drive a steam turbine. Accordingly, when sulfur component
10 is included in these fuels, sulfur dioxide (S02) is included
in exhaust gas after fuel is burned, and a portion of the S02
is oxidized to become sulfur trioxide (S03). Sulfur dioxide
(S02) and sulfur trioxide (S03) may hereinafter be
collectively referred to as "sulfur oxide" or "SOx."
15 [0006]
The exhaust gas from the combustion furnace is normally
treated by an exhaust gas treatment facility provided in a
subsequent stage of the combustion furnace. The exhaust gas
treatment facility comprises a denitrification device, a heat
20 recovery device, an electric dust collector, and a
desulfurization device. In this exhaust gas treatment
facility, when a temperature of the exhaust gas falls to below
the sulfuric acid dew point, S03 in the exhaust gas condenses
into sulfuric acid. Sulfuric acid contributes to the
25 corrosion of a flue and various types of facilities and devices
or the like.
[0007]
For removal of S03 in the exhaust gas, a dry-type
desulfurization process using ultra fine particles (see
30 Unexamined Japanese Patent Application Publication No. JP
5-269341 A (Patent Document 2), for example) and a method of
removing sulfur oxide in the exhaust gas (see Unexamined
Japanese Patent Application Publication No. JP 10-230130 A
(Patent Document 3), for example) are known. In the dry-type
35 desulfurization process disclosed in Patent Document 2,
ultra fine particles of calcium oxide (CaO) are injected into
5
3
an inside of a furnace generating the exhaust gas and/or into
a flue to adsorb sulfur oxide. Moreover, in the removing
method disclosed in Patent Document 3, S03 is treated, for
example, by injecting ammonia between the heat recovery device
and the electric dust collector of the exhaust gas treatment
facility.
[Related Art Document]
[Patent Document]
[0008]
10 Patent document 1: Unexamined Japanese Patent Application
Publication No. JP 10-281443 A
Patent document 2: Unexamined Japanese Patent Application
Publication No. JP 5-269341 A
Patent document 3: Unexamined Japanese Patent Application
15 Publication No. JP 10-230130 A
Summary of the Invention
Problem to be Solved by the Invention
[0009]
In the conventional drying method as disclosed in
20 aforementioned Patent Document 1, the method uses a structure
or a configuration in which it is impossible or difficult,
respectively, to use heat energy from other facilities to
further improve the heat efficiency, and provide effective
use of the heat energy while minimizing factors expected to
25 affect the global warming. This is the problem of the method
disclosed in Patent Document 1.
[0010]
In the conventional dry-type desulfurization process
disclosed in aforementioned Patent Document 2, the ul trafine
30 particles are supplied to the inside of the combustion furnace
from an ultrafine particle injecting inlet provided in the
combustion furnace. However, it is difficult to remove acid
substance wi th high efficiency, depending on where the
injecting position is located. This is the problem of the
35 process disclosed in Patent Document 2. Further, in the
conventional removing method disclosed in aforementioned
4
5
15
10
20
Patent Document 3, since it is required to inject ammonia for
treatment of S03, it is difficult to remove S03 in the exhaust
gas more cheaply and easily. This is the problem of the method
disclosed Patent Document 3. Additionally, there is
increasing demand for more effectively providing the
effective use of the heat energy of the exhaust gas and
achieving efficient operation of the power generation
facility with less problems.
[0011]
A sulfur component (S component) is contained in
high-moisture coal. High-moisture coal containing the S
component combusted in the combustion furnace generates
combustion exhaust gas containing S03. The combustion
exhaust gas is discharged from the combustion furnace. When
the combustion exhaust gas after passing through the air
heater downstream of the combustion furnace is reduced in
temperature below the sulfuric acid dew point, S03 in the
exhaust gas condenses into sulfuric acid. It is thus
concerned that sulfuric acid may contribute to the corrosion
of the flue and various types of facilities and devices or
the like. There is also a problem in that such a sulfuric
acid dew point issue makes it difficult to efficiently recover
the heat of the exhaust gas. Here, the sulfuric acid dew point
refers to a temperature at which S03 and moisture in the gas
start to react and condense into sulfuric acid.
[0012]
In view thereof, it is an obj ect of the present invention
to provide a fuel treatment system, a method for utilizing
of exhaust gas, and an apparatus for utilizing of exhaust gas
30 that may provide the effective use of the heat energy and an
established technology to positively use the low-grade fuel.
It is another object of the present invention to provide a
fuel treatment system, a method for utilizing of exhaust gas,
and an apparatus for utilizing of exhaust gas that may treat
35 S03 in the exhaust gas in a less expensive and easier manner,
effectively provide the effective use of the heat energy of
25
5
5
20
15
10
the exhaust gas, and efficiently operate the power generation
facility with less problems.
Means for Solving the Problem
[0013]
A fuel treatment system according to the present
invention comprises a drying process facili ty for drying fuel
using heat gas, an adjustment device for adjusting a
temperature of the heat gas and supplying the adjusted gas
to the drying process facility, and a control unit for
controlling the adjustment device on the basis of data
relating to a moisture amount and a temperature of a firing
point of the fuel.
[0014]
Further, one embodiment of the present invention may
comprise: a boiler comprising a supply port for supplying
fuel, desulfurizing agent, and oxygen-containing gas and a
discharge port for discharging exhaust gas after the
combustion of the fuel using the oxygen-containing gas; a
first heat-exchange device for exchanging heat between the
exhaust gas discharged from the boiler and heat medium to heat
the heat medium using the exhaust gas; a second heat-exchange
device for exchanging heat between water supplied to the
boiler and heated heat medium after the heat exchange to heat
the water using the heat medium; and a circulation path through
which the heat medium passes, the circulation path circulating
between the first heat-exchange device and the second
heat-exchange device.
[0015]
The adjustment device may also control, for example, the
30 flow rate of the heat gas.
[0016]
25
Further, the adjustment device may comprise, for example,
a heat exchanger.
[0017]
35 The heat exchanger may comprise, for example, a boiler
water supply heater.
5
15
10
6
[0018]
The adjustment device may further comprise, for example,
a distribution device for distributing a heat gas supplied
from the heat gas supply facility to the heat exchanger and
a bypass path, a mixing device for mixing heat gas discharged
from the heat exchanger and heat gas passing through the bypass
path.
[0019]
Preferably, the fuel treatment system further comprises,
a thermal power facility for generating electricity by
combusting the fuel dried using the drying process facility,
wherein thermal power facili ty comprises: a combustion
furnace for combusting the fuel; and a desulfurizing agent
inj ecting device provided to the combustion furnace for
injecting desulfurizing agent into the combustion furnace.
[0020]
In the first heat-exchange device, the circulation path
in contact wi th the exhaust gas may have a surface temperature
higher than a dew point of the exhaust gas. Note that the
20 temperature of the heat medium may be controlled by, for
example, adjusting the flow rate of heat medium bypassing the
second heat-exchange device.
[0021]
The boiler may comprise: a combustion furnace for
25 combusting fuel; a nose section provided in an upper side of
an interior of the combustion furnace for narrowing an
internal space of the combustion furnace, and wherein the
supply port for supplying desulfurizing agent may be located
in the vicinity of the nose section.
30 [0022]
Preferably, the desulfurizing agent is calcium compound,
and the calcium compound includes cement plant dust containing
calcium carbonate (CaC03).
[0023]
35 A method for utilizing of exhaust gas according to the
present invention comprises: supplying coal in a drying
5
10
15
20
7
process facility to dry the coal, the coal containing moisture
and sulfur component, supplying the dried coal in a
combustion furnace to combust the coal, and using heat of
exhaust gas after the combustion, the method further
comprising, supplying desulfurizing agent in the combustion
furnace to desulfurize the exhaust gas in the combustion
furnace, and using heat of the desulfurized exhaust gas as
a heat source for drying the coal.
[0024]
A method for utilizing of exhaust gas according to the
present invention comprises supplying coal in a drying process
facility to dry the coal, the coal containing moisture and
sulfur component, supplying the dried coal in a combustion
furnace to combust the coal, and using heat of exhaust gas
after the combustion, the exhaust gas containing ash content,
the method further comprising the steps of: cooling the
exhaust gas by an exhaust gas temperature reduction device;
mixing the cooled exhaust gas and heat gas having a higher
temperature than the cooled exhaust gas to generate mixed gas;
and supplying the mixed gas in the drying process facility,
wherein the mixed gas is generated at an oxygen concentration
of 10 vol% or less.
[0025]
A method for utilizing of exhaust gas according to the
25 present invention comprises, supplying coal in a drying
process facility to dry the coal, the coal containing moisture,
supplying the dried coal in a combustion furnace to combust
the coal, and us ing heat of exhaust gas after the combust ion,
the method further comprising the steps of: supplying heat
30 gas discharged from a heat-using facility other than the
combustion furnace to the combustion furnace as combustion
air, the heat gas containing oxygen; and supplying the exhaust
gas to the drying process facility, wherein the heat gas has
an oxygen concentration of 15 vol% or more and a temperature
35 of 250°C or more.
[0026]
5
8
The desulfurized exhaust gas may be supplied to the
drying process facility to use heat of the exhaust gas as a
heat source for drying the coal.
[0027]
Heat is exchanged between the desulfurized exhaust gas
and heat medium, and the heat medium heated by the exhaust
gas is supplied to the drying process facility to use the heat
medium as a heat source for drying the coal.
[0028]
10 The desulfurized exhaust gas may be supplied to a dust
collection device to remove ash content contained in the
exhaust gas, and heat of the exhaust gas having the ash content
removed may be used as a heat source for drying the coal.
[0029]
15 The method may further comprise the step of removing the
ash content from the cooled exhaust gas wi th a dust collection
device, wherein the mixed gas may be generated by mixing the
exhaust gas having the ash content removed and the heat gas.
[0030]
20 Preferably, the exhaust gas has an oxygen concentration
of 10 vol% or less.
[0031]
Preferably, the heat gas is heat gas discharged from a
clinker cooler of a cement manufacture facility.
25 [0032]
The method may further comprise the step of supplying
desulfurizing agent in the combustion furnace to desulfurize
exhaust gas in the combustion furnace.
[0033]
30 The combustion furnace may be configured to have, in an
upper side thereof, a nose section for narrowing an internal
space of the combustion furnace, and the desulfurizing agent
may be supplied in the vicinity of the nose section.
[0034]
35 An apparatus for utilizing of exhaust gas according to
the present invention comprises: a drying device for drying
5
9
coal; a combustion device for combusting the dried coal; and
a desulfurizing agent supply device for supplying
desulfurizing agent to the combustion device, an exhaust gas
supply path being provided connecting the drying device and
the combustion device, the exhaust gas supply path supplying
the desulfurized exhaust gas to the drying device, and the
drying device drying the coal using heat of the exhaust gas.
Effects of the Invention
[0035]
10 The present invention may provide the effective use of
the heat energy and an established technology to positively
use the low grade fuel. The present invention may also treat
S03 in the exhaust gas in a less expensive and easier manner,
effectively provide the effective use of the heat energy of
15 the exhaust gas, and efficiently operate the power generation
facility with less problems.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036]
20 FIG. 1 is a functional block diagram of a fuel treatment
system according to all embodiments of the present invention;
FIG. 2 is a block diagram generally illustrating the
entire fuel treatment system according to a first embodiment
of the present invention;
25 FIG. 3 is a block diagram generally illustrating the
entire fuel treatment system according to a second embodiment
of the present invention;
FIG. 4 is a block diagram generally illustrating the
entire fuel treatment system according to a third embodiment
30 of the present invention;
FIG. 5 is a block diagram generally illustrating the
entire fuel treatment system according to a fourth embodiment
of the present invention;
FIG. 6 shows a structure of a combustion furnace of a
35 thermal power facility in a fuel treatment system according
to a fifth embodiment of the present invention;
5
10
15
20
25
30
35
10
FIG. 7 is a flowchart related to control of the fuel
treatment system according to all embodiments of the present
invention;
FIG. 8 shows a structure of a combustion furnace of a
thermal power facility in a fuel treatment system according
to a sixth embodiment of the present invention;
FIG. 9 is a block diagram generally illustrating the
entire fuel treatment system according to the sixth embodiment
of the present invention;
FIG. 10 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a seventh embodiment
of the present invention;
FIG. 11 shows a detailed configuration of FIG. 10;
FIG. 12 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to an eighth embodiment
of the present invention;
FIG. 13 shows a detailed configuration of FIG. 12;
FIG. 14 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a ninth embodiment
of the present invention;
FIG. 15 shows a detailed configuration of FIG. 14;
FIG. 16 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a tenth embodiment
of the present invention;
FIG. 17 shows a detailed configuration of FIG. 16;
FIG. 18 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to an eleventh
embodiment of the present invention.
FIG. 19 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a twelfth embodiment
of the present invention;
FIG. 20 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a thirteenth
embodiment of the present invention;
FIG. 21 shows a detailed configuration of FIG. 20;
FIG. 22 is a block diagram of the entire flow of a method
5
10
15
11
for utilizing of exhaust gas according to a fourteenth
embodiment of the present invention;
FIG. 23 shows a detailed configuration of FIG. 22;
FIG. 24 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a fifteenth
embodiment of the present invention;
FIG. 25 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a sixteenth
embodiment of the present invention;
FIG. 26 shows a detailed configuration of FIG. 25; and
FIG. 27 is a horizontal cross-sectional view of
desulfurizing agent injecting positions of 0.8 M higher and
0.4 L lower in the combustion furnace according to an
embodiment of the present invention.
Best Mode for Carrying Out the Invention
[0037]
With reference to the accompanying drawings,
embodiments of a fuel treatment system, a method for utili zing
20 of exhaust gas, and an apparatus for utilizing of exhaust gas
according to the present invention will be described below
in more detail.
[0038]
[Entire Configuration of a Fuel Treatment System]
25 FIG. 1 is a functional block diagram of a fuel treatment
system according to all embodiments of the present invention.
With reference to FIG. 1, a fuel treatment system 1 comprises
a database (DB) 2, a control unit 3, an adjustment device 4,
and a drying process facility 300. In other words, the
30 treatment system 1 controls a temperature of heat gas supplied
from a not-shown heat gas supply facility using the adjustment
device 4. The adjustment device 4 is controlled by the control
unit 3.
[0039]
35 The control unit 3 may comprise a well-known computer.
Specifically, the control unit 3 controls the adj ustment
5
10
15
12
device 4 on the basis of information from the DB2 to adjust
a temperature of heat gas supplied from a not-shown heat gas
supply facility. The temperature-adjusted heat gas is used
to dry fuel in the drying process facility 300. Specific
examples of the heat gas supply facility and the heat gas
comprise, for example, a hot air production furnace, heating
furnace exhaust gas, boiler exhaust gas, clinker cooler
exhaust gas, or the like. Among qthers, from the point of
view of the effective use of the heat energy, the boiler
exhaust gas and the clinker cooler exhaust gas are preferably
used.
[0040]
The fuel to be dried in the drying process facility 300
is, for example, fuel (coal) that contains moisture and thus
needs to be dried before combustion to improve the combustion
efficiency during the combustion. Typically, the fuel is
so-called low grade fuel, which contains high moisture, such
as high-moisture coal and high-moisture biomass.
[0041]
20 The high-moisture coal comprises sub-bituminous coal
and brown coal. With respect to the moisture amount of the
high-moisture coal, the total moisture content per unit mass
is 20 to 60 mass %, for example. The high-moisture biomass
comprises woody biomass such as wood waste, rice husk, forest
25 land remaining materials, and Palm Kernel Shell, and waste
material biomass such as sludge, a residue, and livestock
excreta, or the like. With respect to the moisture amount
of the high-moisture biomass, the total moisture content is
20 to 70 mass%, for example. Although, in the following,
30 examples are considered where the low grade fuel is used as
the fuel, the present invention is not necessarily limited
thereto. The present invention may also be applied to fuel
that may provide a sufficient combustion efficiency without
the drying process.
35 [0042]
The DB2 stores, for each type of low grade fuel,
13
information on the moisture amount and the temperature of a
firing point IT (oC) of the low grade fuel. As necessary,
the OB2 may store other information than the moisture amount
and the temperature of the firing point IT.
5 [0043]
Note that the information on the moisture amount may
comprise, for example, information on the total moisture
content TM (mass%) and the equilibrium moisture content EM
(mass%) of the low grade fuel. The total moisture content
10 TM is, if the fuel is coal for example, the moisture contained
in the coal before the drying process. Further, the
equilibrium moisture content EM is the moisture content that
reaches the equilibrium state in the atmosphere where the coal
is exposed. The equilibrium moisture content EM depends on
15 the temperature and humidity of the atmosphere.
[0044]
Preferably, the drying process facility 300 dries the
low grade fuel to a predetermined moisture amount.
Specifically, the low grade fuel may be dried such that its
20 moisture content OM (mass% ) after the drying process
(hereinafter referred to as a post-drying moisture content
OM) is a moisture content that is not below the equilibrium
moisture content EM in the atmosphere and is as low as
possible.
25 [0045]
Meanwhile, in the drying process facility 300, it is
required to perform the drying process such that the
temperature GT of the heat gas to be used is a temperature
slightly below the temperature of the firing point IT of the
30 fuel to be dried. A drying process at a temperature above
the temperature of the firing point IT may result in fuel
ignition in the drying process facility 300.
[0046]
Thus, the control portion 3 performs the following
35 operations to control the adjustment means 4 (see FIG. 7
described below) .
5
10
15
20
25
30
35
14
(1) The type of fuel to be dried using the drying process
facility 300 is identified.
(2) The moisture amount and the temperature of the firing
point IT of the fuel identified in the above (1) is acquired
from the database (DB) 2 that stores the information on the
moisture amount and the temperature of the firing point IT.
(3) From the temperature of the firing point IT acquired
in the above (2), the temperature of the heat gas to be used
in the drying process facility 300 is determined.
(4) The moisture amount of the fuel after the drying is
determined.
(5) From the moisture amount of the fuel before the drying
in the above (2) and the moisture amount of the fuel after
the drying in the above (4), the heat amount necessary in the
drying process facility 300 is determined.
(6) From the necessary heat amount in the above (5) and
the temperature of the heat gas in the above (3), the amount
of heat gas to be supplied to the drying process facility 300
is determined.
The control unit 3 and the adjustment device 4 will be
described in more detail below.
[0047]
The control unit 3 identifies the type of fuel to be
combusted in the drying process facility 300 on the basis of
input information input by a user through a not-shown input
device or information automatically recognized by the drying
process facility 300. Further, information on the moisture
amount and the temperature of the firing point IT of the
identified fuel is acquired from the DB2. Then, on the basis
of the moisture amount (for example, the total moisture
content TM and the equilibrium moisture content EM) and the
temperature of the firing point IT of the relevant identified
fuel, the temperature GT(oC) and the post-drying moisture
content OM of the heat gas to be used in the drying process
facility 300 is calculated.
[0048]
5
10
15
20
15
The temperature GT of the heat gas is given by GT = IT
- ex (ex is a predetermined positive constant). The post-drying
moisture content OM is gi ven by OM = EM + ~ (~ is a predetermined
positive constant).
[0049]
Further, information on the fuel mass WC (t/h) to be dried
per unit time is identified on the basis of input information
input by an operator or information automatically recognized
by the drying process facility 300. Then, using the mass WC,
the heat amount QO (MJ/h) necessary per unit time in the drying
process facility 300 and the flow rate VO (m 3 /h) of the heat
gas necessary per unit time are calculated. Using these, the
control unit 3 controls the adjustment device 4.
[0050]
The adjustment device 4 may comprise, for example, a heat
exchanger. In this case, the adjustment device 4 may also
be configured to provide other devices with the difference
(QT-QO) between the heat amount QT of the heat gas supplied
from a not-shown heat gas supply facility and the above heat
amount QO.
[0051]
As described above, the treatment system 1 may determine
the temperature of the heat gas introduced in the drying
process facility 300 or the like on the basis of data held
25 in the OB2 that stores information on the properties of the
fuel to be used. Thus, the adjustment device 4 may provide
a drying process in which the temperature of the heat gas is
below the temperature of the firing point IT of the fuel and
the fuel is dried to an appropriate moisture amount
30 corresponding to the equilibrium moisture content EM.
[0052]
FIG. 7 is a flowchart related to control of the fuel
treatment system according to all embodiments of the present
invention. FIG. 7 illustrates the description in the above
35 (1) to (6). FIG. 7 also illustrates a preferable embodiment
described below. Specifically, an embodiment is shown in
5
10
15
20
25
30
35
16
which excess heat gas (corresponding to QP in FIG. 7) after
the drying process facility 300 takes the necessary heat gas
is used to preheat (heat) the boiler water supply. Thus, the
heat energy may be used much more efficiently. The efficiency
of the boiler may also be improved.
[0053]
The treatment system 1 thus configured may provide the
effective use of the heat energy of the heat gas from a heat
gas supply facility and the positive use of the low grade fuel.
Now, specific examples of the treatment system 1 will be
described below.
[0054]
[First Embodiment]
FIG. 2 is a block diagram generally illustrating the
entire fuel treatment system according to a first embodiment
of the present invention. Note that an example is considered
here where coal is used as the low grade fuel. Wi th reference
to FIG. 2, the treatment system 1 comprises a coal thermal
power station 100, a cement manufacture facility 200 as the
heat gas supply facility, and a coal drying process facility
300.
[0055]
The coal thermal power station 100 is a facility that
uses and combusts coal to generate electricity. The coal
thermal power station 100 may be configured like well-known
coal thermal power facilities. Specifically, the coal
thermal power station 100 first grinds supplied coal to a
predetermined size by a grinding device 101 comprising a
vertical mill or the like. Then, a boiler 102 combusts the
coal at a temperature of, for example, about 1600°C. Coal
of one or more different types of properties may be combined.
[0056]
Then, a heat energy generated by the boiler 102 drives
a steam turbine, thus allowing an electric generator 103 to
generate and supply electricity. Note that a water supply
heater 104 heats a water supply to the fuel combustion boiler
17
using steam from the steam turbine to improve the heat
efficiency of the electric generator 103.
[0057]
Meanwhile, the exhaust gas generated in the boiler 102
5 may have nitrogen oxide removed by a denitrification device
105. The denitrified exhaust gas further has its temperature
reduced by a heat recovery device 106. Heat recovered by the
heat recovery device 106 may be used to increase, for example,
the temperature of combustion air pumped into the boiler 102.
10 After passing through the heat recovery device 106, the
exhaust gas is supplied to an electric dust collector 107.
The electric dust collector 107 collects dust floating in the
exhaust gas.
[0058]
15 After passing through the electric dust collector 107,
the exhaust gas has sulfur oxide removed by a desulfurization
device 108. The exhaust gas is then discharged into the
atmosphere as the exhaust gas. By the above process, the coal
thermal power station 100 of the treatment system 1 according
20 to the first embodiment generates electricity. In the
treatment system 1, before coal is supplied to the grinding
device 101, the coal drying process facility 300 dries the
coal. Here, specific examples of coal to be dried comprises
so-called low grade coal or the like such as sub-bituminous
25 coal and brown coal. The coal is dried by the coal drying
process facility 300 to the post-drying moisture content DM
as described above.
[0059]
Here, the post-drying moisture content DM is a moisture
30 content that is not below the equilibrium moisture content
EM of the coal and is as low as possible. Further, the
equilibrium moisture content EM is here a moisture content
that reaches an equilibrium state in the atmosphere to which
the coal is exposed (such as a drying process facility outlet,
35 a storage silo, or the air atmosphere). The equilibrium
moisture content EM depends on the temperature and humidity
18
5
10
15
20
of the atmosphere. Note that from an operational point of
view, as more moisture content is removed from the coal, a
higher calorific value is achieved, so the dried coal
preferably has as Iowa moisture content as possible. If,
however, the moisture content of the coal discharged from the
coal drying process facility 300 is below the equilibrium
moisture content EM in the atmosphere, the coal will
disadvantageously absorb moisture in the atmosphere.
[0060]
Therefore, to prevent the dried coal from reabsorbing
moisture and ensure the drying efficiency, it is important
that the control unit 3 controls the adjustment device 4 to
control the temperature GT of the heat gas supplied to the
coal drying process facility 300 so that the coal is dried
to a moisture content not below the predetermined equilibrium
moisture content EM. Note that a moisture content not below
the equilibrium moisture content EM is moisture not less than
the equilibrium moisture content EM of the coal, and not more
than 1.3 times of the equilibrium moisture content thereof.
Preferably, it is not less than the equilibrium moisture
content EM of the coal, and not more than 1.2 times of the
equilibrium moisture content.
[0061]
Specifically, when the coal to be dried is, for example,
25 sub-bituminous coal of the total moisture content TM of 25
mass% and the equilibrium moisture content EM of 15 mass%,
the post-drying moisture content OM is as low as possible,
while it should be prevented from being below 15 mass%. For
example, it is from 15 mass% to 19.5 mass%, and preferably
30 from 15 mass% to 18 mass%.
[0062]
Here, if the fuel is coal, for example, the total moisture
content TM refers to the moisture content contained by the
coal before the drying process, i.e., the moisture content
35 contained by the coal sample collected. The total moisture
content TM is measured in conformity to JIS M8820 (method of
5
19
lot-measuring total moisture of various types of coal and
cokes). Further, the equilibrium moisture content EM is
measured using coal after a drying process as a sample, and
according to, for example, JIS A1475 (method of measuring
equilibrium water-content ratio of architectural materials) .
This measurement may provide a curve of equilibrium
water-content ratio of the dried coal.
[0063]
The equilibrium water-content ratio of the coal after
10 a drying process is determined using the curve of equilibrium
water-content ratio provided here and information on the
temperature and relative humidity of above each atmosphere
to which the dried coal is exposed. The determined
equilibrium water-content ratio means a percentage of water
15 mass based on total mass after drying.. Therefore, the
equilibrium moisture content of the coal after a drying
process can be obtained by converting it to the percentage
of the water mass based on the total mass before drying by
the following formula (1).
20 [0064]
[Formula 1]
Equilibrium moisture content (mass%) equilibrium
water-content ratio -;- (100 + equilibrium water-content ratio)
x 100 (1)
25 [0065]
The trea tment system 1 according to the first embodiment
uses, in the coal drying process facility 300, the exhaust
heat energy from the cement manufacture facility 200 to
provide the effective use of the heat energy. In other words,
30 the cement manufacture facility 200 may be configured like
well-known cement manufacture facilities.
[0066]
The cement manufacture facility 200 grinds, for example,
raw materials such as limestone, clay, silica stone, and iron
35 raw materials in a mill 201. The facility 200 then calcinates
the ground raw materials such as limestone, clay, silica stone,
5
10
15
20
25
30
35
20
and iron raw materials in a calcination device 202 using coal
as fuel at a temperature of, for example, about 1450°C. Thus,
cement clinkers are obtained. Then, a clinker cooler 203
cools the calcinated cement clinkers. A mixing mill 204 then
mixes the cooled cement clinkers with gypsum and other
admixtures or the like and grinds the mixture, thus providing
powdery cement.
[0067]
Exhaust gas having heat of about 300°C is discharged from
the clinker cooler 203. However, the exhaust heat of the
exhaust gas has currently been unused and almost just
discharged. The treatment system 1 is configured to use the
unused exhaust heat of the exhaust gas as the heat gas in the
drying process in the coal drying process facility 300 by
little modifying the existing facility.
[0068]
Specifically, the heat gas discharged from the clinker
cooler 203 in the cement manufacture facility 200 is
introduced to a heat exchanger 4A as the adjustment device
4, where the heat exchange is performed under control of the
control uni t 3. Then, the heat gas is adj usted to a
predetermined temperature GT as described above and then
supplied to the coal drying process facility 300.
[0069]
The control uni t 3 acquires from the OB2 information on
the moisture amount (the total moisture content TM and the
equilibrium moisture content EM) and the temperature of the
firing point IT of each type of coal to be dried. According
to the information, the control unit 3 determines the
temperature GT and post-drying moisture content OM of the heat
gas. Further, according to the mass WC (t/h) of the coal to
be supplied to the coal drying process facility 300 per unit
time, the control unit 3 calculates the heat amount QO (MJ/h)
of the coal necessary per unit time and the flow rate VO (m3 /h)
of the heat gas necessary per uni t time in the drying process
facility 300. Then, the control unit 3 controls the heat
21
exchanger 4A to supply the calculated heat amount QD and flow
rate VD.
[0070]
Here, the temperature of the firing point IT is a
5 temperature at which coal ignites. The temperature of the
firing point IT is, for example, a temperature measured
according to JIS K7193 (method of examination of ignition
temperature using a hot-air furnace for plastics)
[0071]
10 Note that a temperature slightly below the temperature
of the firing point IT is, for example, a temperature below
the temperature of the firing point IT by about 80 to 30°C,
and preferably a temperature below the IT by about 50 to 30°C.
Specifically, when sub-bituminous coal having a temperature
15 of a firing point IT of 230°C is to be dried, for example,
the heat gas temperature GT is set to about 150 to 200°C,
preferably about 180 to 200°C.
[0072]
Therefore, the heat exchanger 4A supplies heat gas to
20 the coal drying process facility 300. The heat gas has a
temperature GT and a flow rate VD that may eliminate the risk
of coal ignition in the coal drying process facility 300 while
efficiently drying the coal. As described above, the
treatment system 1 is intended to effectively use the unused
25 exhaust heat in the drying process of the low grade coal in
the coal drying process facility 300. This may thus provide
the effective use of the heat energy and the positive use of
the low grade fuel.
[0073]
30 [Second Embodiment]
FIG. 3 is a block diagram generally illustrating the
entire fuel treatment system according to a second embodiment
of the present invention. Note that in the following, the
portion overlapping the already described portion is provided
35 with the same reference symbol, and its description is omitted.
With reference to FIG. 3, a treatment system 1 according to
5
10
15
20
25
30
35
22
the second embodiment is different from the treatment system
1 according to the first embodiment in that instead of the
heat exchanger 4A in the treatment system 1 according to the
first embodiment, the water supply heater 104 in the coal
thermal power station 100 is used as the adjustment device
4 •
[0074]
Specifically, the heat gas discharged from the clinker
cooler 203 in the cement manufacture facility 200 is
introduced to the water supply heater 104 as the adjustment
device 4. Then, the control uni t 3 controls the water supply
heater 104, as described above, to adjust the temperature GT
and flow rate VD of the heat gas. The adjusted heat gas is
then supplied to the coal drying process facility 300. Such
a configuration may also provide, like the configuration in
the first embodiment, the effective use of the heat energy
and the positive use of the low grade fuel.
[0075]
[Third Embodiment]
FIG. 4 is a block diagram generally illustrating the
entire fuel treatment system according to a third embodiment
of the present invention. With reference to FIG. 4, like the
treatment system 1 according to the second embodiment, a
treatment system 1 according to the third embodiment comprises,
as the adjustment device 4, the water supply heater 104 in
the treatment system 1 according to the second embodiment.
Unli ke the second embodiment, however, the adj ustment device
4 in the third embodiment further comprises a distribution
device 111 and a mixing device 112.
[0076]
Specifically, the heat gas from the clinker cooler 203
in the cement manufacture facility 200 is distributed by the
distribution device 111 comprising a multi-port valve and a
flow path switching valve or the like. Then, some of the heat
gas is supplied to the water supply heater 104 and the rest
is supplied to a bypass path (not shown) provided in parallel
5
10
15
20
25
30
35
23
with the water supply heater 104. Then, the heat gas that
is reduced in temperature by the water supply heater 104 and
the heat gas having passed the bypass path are mixed by the
mixing device 112 such as a mixing val ve. The mixture is then
supplied to the coal drying process facility 300. The
distribution device 111 and the mixing device 112 comprise
a blanch line such as T- or Y-pipe wi th a control valve provided
thereto.
[0077]
In this case, the control unit 3 controls the
distribution device 111 to distribute the flow rate to the
bypass path and the water supply heater 104 such that the mixed
heat gas has a safe temperature. Then, the control unit 3
controls the mixing device 112 to mix the high temperature
gas and the low temperature gas so that the heat gas to be
supplied to the coal drying process facility 300 is controlled
to a predetermined temperature GT and a flow rate VD. In such
a configuration, both of the coal drying process facility 300
and the water supply heater 104 may use the heat, thus
providing the effective use of the heat energy and the positi ve
use of the low grade fuel like the second embodiment.
[0078]
[Fourth Embodiment]
FIG. 5 is a block diagram generally illustrating the
entire fuel treatment system according to a fourth embodiment
of the present invention. With reference to FIG. 5, like the
treatment system according to the first embodiment, a
treatment system 1 according to the fourth embodiment uses
the heat exchanger 4A as the adjustment device 4. Unlike the
treatment system according to the first embodiment, however,
the treatment system 1 according to the fourth embodiment
further comprises the distribution device 111.
[0079]
Specifically, the heat gas from the clinker cooler 203
in the cement manufacture facility 200 is introduced to the
heat exchanger 4A, where the heat exchange is performed under
5
10
15
20
25
30
35
24
control of the control uni t 3 to set the heat gas to a
predetermined temperature GT. Further, the distribution
device 111 is controlled on the basis of the necessary flow
rate VD to the coal drying process facility 300 and the water
supply heater 104. Then, the temperature-controlled heat gas
is distributed to each of the coal drying process facility
300 and the water supply heater 104. Such a configuration
may also provide, like the configuration in the first
embodiment, the effective use of the heat energy and the
positive use of the low grade fuel.
[0080]
Note that although not shown, the coal drying process
facility 300 may be configured to comprise a paddle
agitation-type drier that agitates fuel on a gas distribution
plate with paddles while drying the fuel. The paddle
agitation-type drier has an interior that is divided into an
upper drying chamber and a lower air chamber by a gas
distribution plate, for example. Further, the paddle
agitation-type drier is configured to comprise a large number
of slit openings arranged on the gas distribution plate and
a paddle shaft laterally laid in the drying chamber, the paddle
shaft being rotatable at variable speed.
[0081]
The paddle shaft has a plurality of fuel-agitating
paddles mounted thereto in the axial direction of the paddle
shaft. The paddles are adjacent in the axial direction of
the paddle shaft. The paddles are mounted such that the
mounting angles of the paddles are shifted in phase to each
other as seen in the axial direction. Each paddle is itself
tilted relative to the shaft line of the paddle shaft such
that the fuel is provided wi th an agi tat ion force in the shaft
line direction. The tilt angle is adjustable. Further, a
feeding port and a discharging port for fuel are provided to
one end side and the other end side of the paddle shaft of
the drying chamber, respectively. The heat gas is introduced
to the air chamber, and then the heat gas is sprayed into the
5
10
15
20
25
30
35
25
drying chamber at a high speed through the slit openings on
the gas distribution plate to thereby fluidize the fuel.
[0082]
[Fifth Embodiment]
Further, in the coal thermal power station 100 in the
treatment system 1 according to the above embodiment, the
boiler 102 may have a combustion furnace configured as follows
to effectively treat the exhaust gas from the coal thermal
power station 100. FIG. 6 shows a structure of a combustion
furnace of a thermal power facili ty in a fuel treatment system
according to a fifth embodiment of the present invention.
[0083]
A desulfurizing agent injecting device for injecting
desulfurizing agent is provided in a combustion furnace 20
for combusting fuel. The desulfurizing agent may be supplied
alone and directly in an interior of the combustion furnace
20. Further, the desulfurizing agent may be mixed with
pulverized coal in advance and then be supplied in the interior
of the combustion furnace 20. An injecting inlet for the
desulfurizing agent is provided on the combustion furnace 20
at a position that may provide more suitable and efficient
capture of S03. A preferable form of the inj ecting inlet for
the desulfurizing agent will be described below.
[0084]
With reference to FIG. 6, the desulfurizing agent is
injected into the combustion furnace 20 through a not-shown
desulfurizing agent supply pipe. The desulfurizing agent
supply pipe is connected to a desulfurizing agent injecting
inlet 14 provided in a wall section 20a of the combustion
furnace 20. Preferably, the desulfurizing agent injecting
inlet 14 is provided in the upper portion of the combustion
furnace 20. Additionally, it is particularly preferred that
the desulfurizing agent injecting inlet 14 is formed to enable
injection of the desulfurizing agent 15 into a vicinity
position of a nose section 21 (which may be referred to as
an upper nose section 21) formed upwardly in the combustion
5
26
furnace 20. Thus, the desulfurization (removal of S03) in the
combustion furnace may be efficiently performed. The supply
position of the desulfurizing agent 15 is not limited to the
above position. The supply position may be formed to inject,
for example, the desulfurizing agent 15 into the combustion
furnace 20 as appropriate, even if the nose section 21 is not
formed.
[0085]
The nose is a protruding object provided in a furnace
10 and functioning to divert combustion gas to prevent the
combustion gas from flowing through a short path, but cause
it to pass through a overheater 20b, thereby securing a
retention time of the combustion gas. The nose section 21
redirects the combustion gas flow in the combustion furnace,
15 thus highly mixing the combustion gas. Further, "the
vicinity position of the nose section 21" is a portion shown
by H (or L + M) in FIG. 6.
[0086]
Specifically, "the vicinity position of the nose section
20 21" is included in a range of a height direction defined by
a base of a triangle of the nose section 21. Also, "the
vicinity position of the nose section 21" is a space in the
combustion furnace 20 included in the range of the height
direction, but a space where the overheater 20b is not present.
25 The overheater 20b extends from an upper side of the nose
section 21 to the space of the nose section 21. Then, the
desul furi zing agent 15 is suppl ied to that space. The number
of the desulfurizing agent injecting inlets 14 is 1, or 2 or
more. Among, these numbers in view of appropriately
30 dispersing the desulfurizing agent 15 in the combustion
furnace 20, 2 or more, particularly 4 to 6, is preferable.
If the position of the desulfurizing agent injecting inlet
14 is in the range of "H" of the nose section, a plurality
of the desulfurizing agent inj ecting inlets 14 may be provided
35 in the height direction.
[0087]
5
10
15
20
25
30
35
27
Preferably, the desulfurizing agent 15 comprises
calcium compounds such as calcium hydroxide, calcium oxide,
and calcium carbonate. More preferably, the desulfurizing
agent is cement plant dust comprising calcium carbonate
(CaC03) as a main component. The cement plant dust is
recovered from, for example, exhaust gas of a process for
manufacturing cement raw material. The dust has a mass based
average particle size of about 2]lm, and is available at a very
inexpensive price and in large quantities.
[0088]
The desulfurizing agent 15 is injected into the vicinity
position of the upper nose portion 21 in the combustion furnace
20. The injected desulfurizing agent 15 may thus capture S03
generated by combustion of fuel more sui tably and efficiently.
The cement plant dust comprises dust recovered from the mill
201 in the cement manufacture facility 200 and dust recovered
from exhaust gas from the calcination device 202.
[0089]
Specifically, for example, when calcium carbonate is
used as the desulfurizing agent 15, a decarboxylation reaction
causes the calcium carbonate to become calcium oxide
(CaC03-+CaO), and a desulfurizing reaction causes this calcium
oxide CaO to react with sulfur dioxide S02 to become calcium
sulfate (CaO+S02+0. 502-+CaS04). Further, the calcium oxide
CaO after the decarboxylation reaction captures S03. The
inventors have discovered that the desulfurizing reaction may
be most activated by injecting the desulfurizing agent 15 in
the vicinity position of the upper nose section 21 in the
combustion furnace 20.
[0090]
Regarding amount of supply of desulfurizing agent with
respect to fuel, a molar ratio (Ca/S) of calcium (Ca) to the
sulfur content (S) in the desulfurizing agent provided in the
fuel is preferably between 0.5 and 3, more preferably between
1 and 2.5. If the molar ratio exceeds 3, the amount of dust
increases. Specifically, the inventors have experimentally
5
10
15
20
25
30
35
28
demonstrated that the desulfurizing agent 15 injected into
a position lower than the upper nose section 21 in the
combustion furnace 20 provides a high internal temperature
of the furnace, which causes CaO to be used in modification
of coal ash (cement mineralization reaction) or the like and
causes a reverse reaction of the desulfurization or the like.
The inventors have also demonstrated that the desulfurizing
agent 15 injected into a position higher than the upper nose
section 21 in the combustion furnace 20 provides a low internal
temperature of the furnace, which causes an insufficient
decarboxylation reaction, which may cause insufficient
capt ure 0 f S03.
[0091]
In contrast, the desulfurizing agent 15 injected into
a vicinity position of the upper nose section 21 as described
above may ensure a moderate contact time between CaO and S03.
Further, the highly disturbed gas flow effectively
distributes CaO in gas layers in the combustion furnace 20
and CaO captures S03, thus activating the desulfurization
reaction.
[0092]
This may prevent the phenomenon in which the
concentration of S03 is locally increased in the combustion
furnace 20, thus causing condensation, and the condensation
generates sulfuric acid, which corrodes the portion to which
the sulfuric acid adheres. Note that in inj ecting the
desulfurizing agent 15, the preferable internal temperature
of the combustion furnace 20 is, for example, in the range
of 1050°C to 1150°C. The above configuration may effectively
remove S02 and S03 in the combustion furnace 20, thus
effectively treating the exhaust gas in the coal thermal power
station 100.
[0093]
[Sixth Embodiment]
FIG. 8 shows a structure of a combustion furnace of a
thermal power facility in a fuel treatment system according
5
10
15
20
25
30
35
29
to a sixth embodiment of the present invention. FIG. 9 is
a block diagram generally illustrating the entire fuel
treatment system according to the sixth embodiment of the
present invention. With reference to FIG. 8 and FIG. 9, a
fuel treatment system 1 according to this embodiment is
applicable to a coal thermal power station 100.
[0094]
The coal thermal power station 100 comprises, by way of
example, the grinding device 101 for grinding coal used as
fuel, the boiler 102 for combusting the coal to evaporate
externally supplied water W4 to provide steam, the electric
generator 103 comprising a not-shown steam turbine, and the
water supply heater 104 for heating water W3 supplied to the
boiler 102.
[0095]
The boiler 102 comprises, for example, a supply port for
supplying fuel, desulfurizing agent, and oxygen-containing
gas, and a discharge port for discharging exhaust gas after
combusting the fuel using the oxygen-containing gas. The
fuel is carbonaceous and is combusted wi th oxygen. The
oxygen-containing gas is gas that contains oxygen. Specific
examples of the oxygen-containing gas comprise air, oxygen,
or the like. The supply port for supplying the fuel, the
desulfurizing agent, and the oxygen-containing gas may be
provided as three separate supply ports. Further, a portion
of the oxygen-containing gas and the fuel may be supplied
through the same supply port of the boiler 102.
[0096]
The treatment system 1 comprises a desulfurizing agent
supply device 10 for supplying the desulfurizing agent in the
combustion furnace of the boiler 102, the denitrification
device 105, the heat recovery device 106, an indirect heat
exchange mechanism 110, and the electric dust collector 107.
Note that the denitrification device 105 is an arbitrary
configuration, and may be omi tted in the configuration of the
treatment system 1. Further, the electric dust collector 107
5
10
30
may be replaced with a collection device such as a bag filter.
[0097]
First, the desulfurization process in the combustion
furnace 20 of the boiler 102 (the internal furnace
desulfurization) will be described. With reference to FIG.
8, in the treatment system 1, the desulfurizing agent supply
device 10 comprises, for example, a storage tank 11 for storing
desulfurizing agent 15 transferred by a truck 90 or the like,
and a constant rate discharge mechanism 12 and a blower 13
for supplying the desulfurizing agent 15 stored in the storage
tank 11 to the combustion furnace 20 as appropriate.
[0098]
After being transferred from the storage tank 11 by the
constant rate discharge mechanism 12 and the blower 13, the
15 desulfurizing agent 15 is injected and supplied into the
combustion furnace 20 through, for example, a not-shown
desulfurizing agent supply pipe.
[0099]
Note that in injecting the above desulfurizing agent 15
20 in the vicinity position of the upper nose section 21, the
preferable internal temperature of the combustion furnace 20
is in the range of about 1050°C to 1150°C. Then, after having
its S02 and S03 removed in the combustion furnace 20 as
described above, the exhaust gas is discharged from the
25 combustion furnace 20 through a flue 22, and then deni trif ied
by, for example, the above denitrification device 105.
Further, the exhaust gas is reduced in temperature by the heat
recovery device 106 (the temperature is decreased), and then
supplied to a gas-water heat exchanger 121 provided as a first
30 heat-exchange device in the indirect heat exchange mechanism
110.
[0100]
In the gas-water heat exchanger 121, circulating heat
medium W1 circulating through a circulation condui t 50
35 followed by a conduit 51 exchanges the heat of the exhaust
gas, and then the heat of the circulating heat medium W1 is
31
provided to water W2 by a heat exchanger 122 provided as a
second heat-exchange device.
[0101]
Note that conventionally, exhaust gas discharged from
5 the combustion furnace 20 contains 803 at about 1% of 802, and
a sulfuric acid dew point is about 120°C to 130°C. Thus, the
heat recovery from the exhaust gas is limi ted up to a
temperature of about 150°C of the exhaust gas. In contrast,
in the treatment system 1 according to the sixth embodiment,
10 the desulfurizing agent 15 injected into the vicinity position
of the upper nose section 21 in the combustion furnace 20
removes 803 in exhaust gas in advance. The sulfuric acid dew
point may thus be reduced drastically. The inventors have
demonstrated that specifically, the exhaust gas may thus be
15 cooled to a temperature of, for example, about 100°C by the
gas-water heat exchanger 121, thereby increasing the heat
recovery amount and thus significantly improving the energy
efficiency.
[0102]
20 The recovered heat energy is heat-exchanged by the
gas-water heat exchanger 121 wi th the circulating heat medium
W1 to increase the W1 temperature to about 75°C. The
circulating heat medium W1 is then sent through the
circulation conduit 50 to the heat exchanger 122 where the
25 heat medium W1 is used to preheat the water W2. The energy
efficiency of the boiler 102 may thus be improved. If, for
example, in a power generation boiler at the level of the main
steam amount of 150 t/h, the heat is recovered from the exhaust
gas so that the gas temperature is reduced from 150°C to 100°C,
30 the heat efficiency may be improved by 2 to 3%. Further, the
crude oil reduction is 1970 Kl/year, and the C02 reduction
is 6800 t/h. Note that the surface of the line 51 in the
gas-water heat exchanger 121 is in contact with the exhaust
gas, and thus if the surface temperature is below the dew-point
35 of the exhaust gas, condensation will occur.
[0103]
5
10
15
20
25
30
35
32
In this case, it is concerned that coal ash adheres to
the inside of the gas-water heat exchanger 121 including the
conduit 51 or the like, thus blocking the gas flow channel.
Thus, in the indirect heat exchange mechanism 110, in order
to ensure that the surface temperature of the conduit 51 is
not below the dew-point of the exhaust gas, it is preferred
to appropriately manage the temperature of the circulating
heat medium WI circulating through the circulation conduit
50, appropriately set the heat exchange by the heat exchanger
122, and appropriately manage the surface temperature of the
conduit 51. Therefore, in the heat exchanger 122, it is
preferred to exchange heat between the circulating heat medium
WI circulating through the circulation conduit 50 and the
water W2 such that the temperature of the heat medium WI is
not tob reduced in the heat exchanger 122.
[0104]
For example, in a coal power generation boiler at the
level of the main steam amount of 150 tlh, a bypass line (not
shown) is provided for adjusting the amount of heat medium
passing through the heat exchanger 122 such that the
temperature of the circulating heat medium WI returning to
the gas-water heat exchanger 121 is a temperature (for example
55°C) higher than the dew-point of the exhaust gas (for example,
48°C)
[0105]
Preferably, the bypass amount is adjusted in the range
of 0 to 80% of the circulating heat medium amount. Further,
the bypass amount depends on the temperature of the water W2
externally supplied. If, for example, the water W2 is
supplied at 48°C, the bypass ratio of the circulating heat
medium WI is 0% (the total amount passes through the heat
exchanger 122), and if the water W2 is at 25°C, the bypass
ratio of the circulating heat medium WI is about 60%.
[0106]
In this way, each device such as the gas-water heat
exchanger 121 does not need to be made of expensive corrosion
5
10
15
20
25
30
35
33
resistant materials. For example, the material of portions
in contact with the exhaust gas, such as the conduit 51, may
be made of an inexpensive carbon steel (carbon steel) material,
or the like. Further, the boiler may be operated stably
without the gas flow channel blocked. Note that it has been
found that the reduction of the temperature of the exhaust
gas from the combustion furnace 20 by the indirect heat
exchange mechanism 110 as described above largely affects the
maintenance and improvement of the collection performance of
the electric dust collector 107 provided at the next stage.
[0107]
Specifically, in the treatment system 1 according to the
sixth embodiment, the removal of S03 in the exhaust gas by
the desulfurizing agent 15 in the combustion furnace 20 gives
a certain solution to problems such as corrosion. However,
excess removal of S03 in the exhaust gas may significantly
reduce the collection performance of the electric dust
collector 107.
[0108]
It is generally believed that the collection performance
of the electric dust collector 107 depends on the elements
of (A) exhaust gas temperature, (B) exhaust gas speed (flow
rate), and (C) S03 concentration, and that the higher (C) the
S03 concentration is, the higher the collection performance
is. The treatment system 1 according to the sixth embodiment
removes S03 using the desulfurizing agent 15 injected into
the vicinity position of the upper nose section 21 in the
combustion furnace 20. Therefore, when exhaust gas having
a low concentration of S03 is supplied to the electric dust
collector 107, the expected collection effect may not be
obtained.
[0109]
Therefore, the heat recovery device 106 and the indirect
heat exchange mechanism 110 are provided between the
combustion furnace 20 and the electric dust collector 107 to
reduce the temperature of exhaust gas discharged from the
5
10
15
20
25
30
35
34
combustion furnace 20. This may reduce the volume of the
exhaust gas and the flow rate of the exhaust gas. Thus, the
concentration of S03 in the exhaust gas may not be enough to
affect the collection performance of the electric dust
collector 107, thereby maintaining and improving the
collection performance. Note that the exhaust gas discharged
from the electric dust collector 107 is transferred by a blower
48 and discharged through a stack 49 into the atmosphere.
[0110]
Further, with reference to FIG. 9, it is preferable that
coal used in the coal thermal power station 100 is dried by,
for example, the coal drying process facility 300. Further,
according to the sixth embodiment, the coal thermal power
station 100 comprises the cement manufacture facility 200
provided along with it. The cement manufacture facility 200
discharges heat gas from the clinker cooler 203 described
below. The heat gas is used in the water supply heater 104
to heat the water W3 supplied to the boiler 102. This provides
a configuration that may totally effectively use the heat
energy of the exhaust gas.
[0111]
In addition to being discharged from the cement
manufacture facility 200, the heat gas may be discharged from,
for example, a hot air production furnace. The heat gas may
also be gases such as heating furnace exhaust gas and boiler
exhaust gas. Among others, in terms of the effective use of
the heat energy, it is preferable to use the boiler exhaust
gas and the clinker cooler exhaust gas. Here, coal or low
grade fuel may not need to be dried depending on the contained
moisture amount. If so, then a configuration may be provided
that the coal drying process facility 300 is omitted.
[0112]
In the coal thermal power station 100, the dried coal
supplied from, for example, the coal drying process facility
300 is ground to a predetermined size by the grinding device
101, and the ground coal is combusted in the combustion furnace
35
20 of the boiler 102 (see FIG. 8).
[0113]
Then, the heat energy evaporates the water W4 supplied
from the water supply heater 104 into steam. The steam is
5 used in the electric generator 103 for power generation and
power supply. Note that the water supply heater 104 may be
configured to receive a feedback of the excess steam from the
electric generator 103 and use the steam to heat the water
W3 supplied to the boiler 102. Thus, the heat efficiency of
10 the electric generator 103 may be improved.
[0114]
The water supply heater 104 may also be configured to
use the heat gas from the cement manufacture facility 200 to
heat the water W3.
15 [0115]
Meanwhile, the exhaust gas generated in the boiler 102
has its sulfur oxide (Sax) removed by the desulfurizing agent
supplied in the combustion furnace 20 from the desulfurizing
agent supply device 10. Additionally, the denitrification
20 device 105, for example, removes the nitrogen oxide (NOx).
The desulfurized and denitrified exhaust gas further has its
temperature reduced by the heat recovery device 106.
[0116]
The heat recovered by the heat recovery device 106 may
25 be used to raise, for example, the temperature of the
combustion air pumped into the boiler 102. The heat recovered
by the heat recovery device 106 may also be used to raise the
temperature of drying air for drying the coal in the grinding
device 101. After passing through the heat recovery device
30 106, the exhaust gas is supplied to the gas-water heat
exchanger 121 in the indirect heat exchange mechanism 110.
[0117]
In the gas-water heat exchanger 121, the exhaust gas
supplied from the heat recovery device 106 and the circulating
35 heat medium WI circulating through the circulation conduit
50 are indirectly contacted via the conduit 51 of the
5
10
36
circulation conduit 50 to perform the heat exchange. Thus,
the gas-water heat exchanger 121 is configured to cool the
exhaust gas supplied from the heat recovery device 106. The
heat medium in the present invention is a medium for
transferring heat to other parts. Note that the circulating
heat medium WI may comprise water, silicone oil, mineral oil,
or the like. Among others, in view of the heat transfer, water
is preferable. The indirect heat exchange mechanism 110
comprises the gas-water heat exchanger 121 as well as the heat
exchanger 122, which are connected via the circulation condui t
50.
[0118]
The circulating heat medium WI circulating through the
circulation conduit 50 is heated by the gas-water heat
15 exchanger 121, and introduced in the heat exchanger 122. The
heat exchanger 122 brings the externally supplied water
(preferably deionized water) W2 to be supplied to the boiler
102 into contact with the circulation conduit 50, thus
providing the heat energy of the circulating heat medium WI
20 to the water W2 to heat the water W2. The heated water W3
is supplied to the water supply heater 104.
[0119]
A bypass line (not shown) is provided for adjusting the
amount of heat medium passing through the heat exchanger 122
25 such that the temperature of the circulating heat medium WI
returning to the gas-water heat exchanger 121 is a temperature
(for example 55°C) higher than the dew-point of the exhaust
gas (for example, 48°C). Preferably, the bypass amount is
adjusted in the range of 0 to 80% of the circulating heat medium
30 amount. Further, the bypass amount depends on the
temperature of the water W2 externally supplied.
[0120]
If, for example, the water W2 is supplied at 48°C, the
bypass ratio of the circulating heat medium WI is 0% (the total
35 amount passes through the heat exchanger 122) , and if the water
W2 is at 25°C, the bypass ratio of the circulating heat medium
5
15
10
37
W1 is about 60%. Note that after passing through the gas-water
heat exchanger 121, the exhaust gas is supplied to the electric
dust collector 107.
[0121]
After passing through the electric dust collector 107,
the exhaust gas is discharged into the atmosphere as exhaust
gas. By the above process, the coal thermal power station
100 generates power.
[0122]
Note that the coal thermal power station 100 of the
treatment system 1 according to the sixth embodiment may be
configured to use, in heating the water W3 by the water supply
heater 104, the heat energy of the heat gas supplied from the
cement manufacture facility 200 provided along with the power
station 100, thus providing the effective use of the heat
energy.
[0123]
The cement manufacture facility 200 may be configured
like well-known cement manufacture facilities 200. The
20 clinker cooler 203 discharges heat gas having heat of, for
example, about 300°C. However, the heat energy of the heat
gas has currently been unused and almost just discharged. The
treatment system 1 according to the sixth embodiment is
configured to be able to use the heat gas in the water supply
25 heating process in the coal thermal power station 100 by little
modifying the existing facility.
[0124]
Specifically, the heat gas discharged from the clinker
cooler 203 in the cement manufacture facility 200 is
30 introduced in the water supply heater 104 to perform the heat
exchange. Then, the water W3 heated by the heat exchanger
122 of the indirect heat exchange mechanism 110 is further
heated and supplied to the boiler 102 as the water W4. Thus,
the treatment system 1 may provide the effective use of the
35 heat energy. Note that the exhaust gas discharged from the
water supply heater 104 may further be used in, for example,
5
10
38
the drying process in the coal drying process facility 300.
[0125]
[Seventh Embodiment]
FIG. 10 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a seventh embodiment
of the present invention. FIG. 11 shows a detailed
configuration of FIG. 10. With reference to FIG. 10 and FIG.
11, the method for utilizing of exhaust gas according to the
seventh embodiment is applied to the drying process facility
300 as a drying means mainly for drying coal provided as the
low grade fuel and the coal thermal power station 100 using
the dried coal supplied from the drying process facility 300
for the combustion.
[0126]
15 The coal thermal power station 100 comprises, by way of
example, the grinding device 101, the boiler 102, the electric
generator 103, and the water supply heater 104 for heating
deionized water supplied to the boiler 102. The coal thermal
power station 100 also comprises the desulfurizing agent
20 supply device 10, the distribution device 111 for distributing
exhaust gas from the combustion furnace 20, the
denitrification device 105, an exhaust gas temperature
reduction means 30, the electric dust collector 107, and the
mixing facility 113.
25 [0127]
Note that the denitrification device 105 and the mixing
facility 113 are arbitrary configurations, and may be omitted
in the configuration of the coal thermal power station 100.
The coal used as fuel to be dried by the drying process facility
30 300 is any coal that comprises, for example, moisture and
sulfur component and needs to be dried before combustion.
[0128]
Meanwhile, the exhaust gas generated in the combustion
furnace 20 of the boiler 102 is discharged from the combustion
35 furnace 20 at a temperature of, for example, about 300°C to
400°C after S03 in the combustion gas is removed in the
5
10
15
20
25
30
35
39
combustion furnace 20 (the internal furnace desulfurization)
by the desulfurizing agent 15 supplied in the combustion
furnace 20 from the desulfurizing agent supply device 10.
[0129]
The heat of the discharged exhaust gas is used as a heat
source for drying the coal. There are various embodiments
of using the heat of the exhaust gas. FIG. 10 shows an
embodiment where the desulfurized exhaust gas is supplied to
the drying process facility 300 through an exhaust gas supply
path, the exhaust gas supply path connecting the combustion
furnace used as the combustion means and the drying process
facility used as the drying means. It is an embodiment where
the heat of the exhaust gas is used as the heat source for
drying the coal. The exhaust gas supply path supplies the
desulfurized exhaust gas to the drying process facility 300.
The drying process facility 300 uses the heat of the exhaust
gas to dry the coal. Thus, a configuration is provided that
may provide the effective use of the heat energy of the exhaust
gas.
[0130]
Preferably, the discharged exhaust gas is cooled as
necessary, and then used to dry the coal in the drying process
facility 300. The discharged exhaust gas may also be
introduced in and distributed by the distribution device 111
having, for example, a distribution line and a control valve
or the like. Some of the exhaust gas may thus be used to dry
the coal in the drying process facility 300.
[0131]
Further, the rest of the exhaust gas distributed by the
distribution device 111 is introduced in, for example, the
denitrification device 105 in the subsequent stage, where
nitrogen oxide (NOx) is removed. The desulfurized and
denitrified exhaust gas is further introduced in an exhaust
gas temperature reduction facility 30 disposed in the
subsequent stage of the deni trification device 105. The
temperature of the exhaust gas is thus reduced.
5
10
40
[0132]
The heat recovered by the exhaust gas temperature
reduction facility 30 may be used to, for example, raise the
temperature of the combustion air (oxygen-containing gas)
pumped into the boiler 102. The heat recovered by the exhaust
gas temperature reduction facility 30 may also be used to,
for example, raise the temperature of the drying air for drying
the coal in the grinding device 101. After passing through
the exhaust gas temperature reduction facility 30 and having
its temperature reduced, the exhaust gas is supplied to the
electric dust collector 107 provided as the dust collection
means.
[0133]
The electric dust collector 107 collects dust (ash
15 content) floating in the exhaust gas. After having its dust
(ash content) collected and removed, and passing through the
electric dust collector 107, the exhaust gas is discharged
into the atmosphere as exhaust gas. Note that the dust
collected by the electric dust collector 107 is supplied to,
20 for example, the mixing facility 113. The mixing facility
113 mixes separately transferred dust and a hydrous organic
waste material such as sludge, a residue, or livestock
excreta.
[0134]
25 As described above, dust (ash content) contains a large
amount of calcium oxide (CaO). As dust acts as a desiccant,
dust may be mixed with a hydrous organic waste material to
dry the hydrous organic waste material wi thout using a
separate desiccant or a drying process. By the above process,
30 the coal thermal power station 100 generates power.
[0135]
Note that after having its S02 and S03removed in the
combustion furnace 20, the exhaust gas is di scharged from the
combustion furnace 20 through the flue 22. Some of the
35 discharged exhaust gas is supplied to the drying process
facility 300 via the distribution device III and the rest is
41
5
15
25
20
10
supplied to the exhaust gas temperature reduction facility
30.
[0136]
The exhaust gas temperature reduction facility 30
comprises, for example, a gas air heater (GAH) 31 and the
gas-water heat exchanger 121 or a water spray device 33. Here,
the temperature of the exhaust gas may be reduced in three
ways: (1) by improvement of the ability (performance) of the
gas air heater, (2) by indirect cooling, and (3) by direct
cooling.
[0137]
However, for (3) direct cooling (i. e., for example,
cooling by spraying water in the exhaust gas), dust contained
in the exhaust gas may adhere to the inside of the exhaust
gas temperature reduction facility 30, thus providing
clogging or the like. Therefore, in the seventh embodiment,
al though (3) direct cooling may be used, (2) indirect cooling
may preferably be used.
[0138]
Specifically, in the exhaust gas temperature reduction
facility 30, the circulating heat medium (for example, water)
of the gas-water heat exchanger 121 disposed downstream of
the gas air heater 31 exchanges heat with the exhaust gas,
and the exchanged heat is used to preheat the water supply
to the combustion furnace 20.
[0139]
In the method for utilizing of exhaust gas according to
the seventh embodiment, the desulfurizing agent 15 injected
into the combustion furnace 20 of the boiler 102, preferably
30 the desulfurizing agent 15 injected into the vicinity position
of the upper nose section 21 in the combustion furnace 20
removes S03 in exhaust gas in advance. This may drastically
reduce the sulfuric acid dew point.
[0140]
35 Thus, specifically, the exhaust gas temperature
reduction facility 30 may cool the exhaust gas to a temperature
5
42
of, for example, about 100°C. The inventors have
demonstrated that the heat recovery amount may thus be
increased, thereby significantly improving the energy
efficiency. Further, associated with this, each device or
the like provided in the exhaust gas temperature reduction
facili ty 30 needs not to be made of expensi ve corrosion
resistant materials.
[0141]
For example, the material of a portion in contact with
10 the exhaust gas in the gas-water heat exchanger 121 of the
exhaust gas temperature reduction facili ty 30 may be an
inexpensive carbon steel (carbon steel) material. In the
coal thermal power station 100 according to the seventh
embodiment, the desul fur i zing agent 15 inj ected into the
15 combustion furnace 20 of the boiler 102, preferably the
desulfurizing agent 15 injected into the vicinity position
of the upper nose section 21 removes S03, as described above.
In addition, the exhaust gas temperature reduction facility
30 is provided between the combustion furnace 20 and the
20 electric dust collector 40.
[0142]
The exhaust gas temperature reduction facility 30 may
,
reduce the temperature of the exhaust gas discharged from the
combustion furnace 20 and distributed by the distribution
25 device Ill. The concentration of S03 in the exhaust gas may
thus not be enough to affect the collection performance of
the electric dust collector 107, thereby maintaining and
improving the collection performance. Note that the dust
collected by the electric dust collector 107 from the exhaust
30 gas is supplied to the mixing facility 113, where the dust
is used as a desiccant for the hydrous organic waste material
separately transferred to the mixing facility 113.
[0143]
The coal is dried by the drying process facility in
35 advance before it is combusted in the combustion furnace. In
the drying process facility 300, the exhaust gas is used as
5
43
the drying heat source. Note that the temperature of the
exhaust gas is preferably set to a temperature that is low
enough to suppress the ignition of the coal in the drying
process facility 300 and is as high as possible. As described
above, the drying process facility 300 dries so-called low
grade coal such as sub-bituminous coal, brown coal, or ignite
such that the dried coal has a predetermined moisture.
[0144]
Note that the method for utilizing of exhaust gas
10 according to the seventh embodiment may be configured to use
the hea t energy of the exhaust gas from the combustion furnace
20 of the boiler 102 as the drying air supplied to the drying
process facility 300 for drying coal to be supplied to the
coal thermal power station 100, thus providing the effective
15 use of the heat energy. Into the air chamber of the paddle
agitation-type drier of the drying process facility 300, the
exhaust gas as well as other heat gases, drying air, or the
like may be introduced for drying.
[0145]
20 As described above, according to the method for
utilizing of exhaust gas according to the seventh embodiment,
the exhaust heat from the coal thermal power station 100 may
be effectively used and 803 in the exhaust gas may be removed,
and thus the durability of the facility may be improved and
25 sulfur (8) content in the system may be reduced. This may
provide the effective use of the heat energy and an established
technology to positively use the low grade fuel or the like.
[0146]
[Eighth Embodiment]
30 FIG. 12 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to an eighth embodiment
of the present invention. FIG. 13 shows the detailed
configuration of FIG. 12. With reference to FIG. 12 and FIG.
13, the method for utilizing of exhaust gas according to the
35 eighth embodiment is different from the method according to
the seventh embodiment in that the desulfurized exhaust gas
5
10
15
20
25
30
35
44
to be used as the drying heat source in the drying process
facility 300 is exhaust gas that passes through the exhaust
gas temperature reduction facility 30 and the electric dust
collector 107 by which its temperature is reduced and its dust
(ash content) is removed and that is further distributed by
the distribution device 111 installed in the subsequent stage.
[0147]
Specifically, the exhaust gas from the boiler 102 is
reduced in temperature by the exhaust gas temperature
reduction facility 30, and then supplied to the electric dust
collector 107 where dust in the exhaust gas is removed. Then,
some of the exhaust gas from the electric dust collector 107
is distributed by the distribution device 111 and supplied
to the drying process facility 300. The rest of the exhaust
gas is discharged into the atmosphere. Preferably, the
exhaust gas with its dust removed is used as the heat source
for drying coal, thus preventing dust adhesion in the drying
process facility or the like. This may also provide, like
the seventh embodiment, the effective use of the heat energy
and an established technology to posi ti vely use the low grade
fuel.
[0148]
[Ninth Embodiment]
FIG. 14 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a ninth embodiment
of the present invention. FIG. 15 shows the detailed
configuration of FIG. 14. With reference to FIG. 14 and FIG.
15, the method for utilizing of exhaust gas according to the
ninth embodiment is different from the method according to
the seventh embodiment in that the heat exchange is mainly
performed between the desulfurized exhaust gas and the heat
medium, and the heat medium heated by the heat of the exhaust
gas is used as the drying heat source in the drying process
facility 300. FIG. 14 shows an embodiment where the heat
exchange is performed between the desulfurized exhaust gas
and the heat medium, and the heat medium heated by the exhaust
5
10
15
20
25
30
35
45
gas is supplied to the drying process facility and used as
the heat source for drying the coal.
[0149]
Specifically, the desulfurized exhaust gas is
introduced, after passing through the gas air heater 31 and
having its temperature reduced, into the gas-water heat
exchanger 121. Between the gas-water heat exchanger 121 and
the drying process facility 300, the circulation conduit 50
is provided, and circulating heat medium W1 circulates through
the circulation condui t 50. In the gas-water heat exchanger
121, the circulating heat medium W1 circulating through the
circulation conduit 50 followed by the conduit 51 exchanges
the heat of the exhaust gas.
[0150]
The circulating heat medium W1 is heated by the heat of
the exhaust gas in the gas-water heat exchanger 121, and after
being raised to a predetermined temperature, the heat medium
W1 is supplied to the drying process facility 300 through the
circulation conduit 50. In the drying process facility 300,
instead of the drying heat source (for example, air) or along
with the drying air, the heat of the circulating heat medium
W1, which heat is recovered from the exhaust gas, is used as
the drying heat source to dry the coal as described above.
[0151]
Note that in the ninth embodiment, the coal thermal power
station 100 may be configured to comprise, for example, the
cement manufacture facility 200 provided along with it. The
method for utilizing of exhaust gas according to the ninth
embodiment is configured to be able to use the heat gas in
the water supply heating process in the coal thermal power
station 100 by little modifying the existing facility.
[0152]
Specifically, for example, the heat gas discharged from
the clinker cooler 203 in the cement manufacture facility 200
is introduced in the water supply heater 104 for the heat
exchange, and thus the water introduced to the water supply
5
10
15
20
25
30
35
46
heater 104 is heated and supplied to the boiler 102. Therefore,
the ninth embodiment may provide the effective use of the heat
energy.
[0153]
Note that the exhaust gas discharged from the water
supply heater 104 may further be used in, for example, the
drying process in the drying process facility 300. The use
of the exhaust gas according to the ninth embodiment may also
provide, like the seventh embodiment, the effective use of
the heat energy and an established technology to positively
use the low grade fuel. In the ninth embodiment, the heat
exchange is performed between the desulfurized exhaust gas
and the heat medium, and the heat-exchanged exhaust gas is
discharged into the atmosphere via an electric dust collector
107. After the desulfurized exhaust gas is supplied in the
dust collection means in advance and the ash content contained
in the exhaust gas is removed, the heat exchange may be
performed between the exhaust gas and the heat medium.
[0154]
[Tenth Embodiment]
FIG. 16 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a tenth embodiment
of the present invention. FIG. 17 shows the detailed
configuration of FIG. 16. With reference to FIG. 16 and FIG.
17, the method for utilizing of exhaust gas according to the
tenth embodiment is different from the method according to
the ninth embodiment in that the heat exchange is mainly
performed between the desulfurized exhaust gas and the heat
medium, and some of the heat medium is used to heat the water
to be supplied to the boiler 102.
[0155]
Specifically, the desulfurized exhaust gas is supplied,
after passing through the gas air heater 31 and having its
temperature reduced, in the indirect heat exchange mechanism
110 having the gas-water heat exchanger 121 and the heat
exchanger 122. In the indirect heat exchange mechanism 110,
47
5
10
15
25 I
the gas-water heat exchanger 121 brings the circulating heat
medium WI circulating through the primary circulation condui t
50A into indirect contact with exhaust gas to exchange the
heat of the exhaust gas, and supplies the heat to the drying
process facility 300. Further, a circulating heat medium W1a,
which is a portion of the circulating heat medium WI, is
supplied via a secondary circulation conduit 50B to the heat
exchanger 122 where the heat is given to the water W2.
[0156]
The heat exchanger 122 brings the externally supplied
water (preferably deionized water) W2 to be supplied to the
boiler 102 into contact wi th the secondary circulation condui t
50B, thus providing the heat energy of the circulating heat
medium W1a to the water W2 to heat the water W2. Note that
the heated water W3 is supplied to the water supply heater
104.
[0157]
The primary circulation conduit 50A and the secondary
circulation conduit 50B are connected in the gas-water heat
exchanger 121 by a not-shown valve device or the like such
that each path may be branched. Therefore, under a
predetermined control, the circulating heat media WI and W1a
may circulate through the primary circulation condui t 50A and
the secondary circulation conduit 50B, respectively.
[0158]
The heat energy recovered by the indirect heat exchange
mechanism 110 is used as follows for example: the circulating
heat medium WI is heat exchanged in the gas-water heat
exchanger 121 and raised to a temperature of about 75°C, and
30 then the heat medium W1a, which is a portion of the medium
WI, is passed through the secondary circulation conduit 50B
and used to preheat the water W2 in the heat exchanger 122.
Thus, the energy efficiency of the boiler 102 may be improved.
Note that the dew-point is the temperature at which the
35 moisture in the gas begins to condense.
20
[0159]
5
10
48
In this case, it is concerned that coal ash adheres to
the inside of the gas-water heat exchanger 121 including a
conduit or the like, thus blocking the gas flow channel. Thus,
in the indirect heat exchange mechanism 110, in order to ensure
that the surface temperature of the conduit is not below the
dew-point of the exhaust gas, it is preferred to appropriately
manage the temperature of the circulating heat medium W1
circulating through the primary circulation conduit 50A,
appropriately set the heat exchange by the heat exchanger 122,
and appropriately manage the surface temperature of the
conduit.
[0160]
Therefore, in the indirect heat exchange mechanism 110,
in order that the circulating heat media W1 and W1a circulating
15 through the primary circulation conduit 50A and the secondary
circulation conduit SOB are not too reduced in temperature
in the drying process facility 300 or the heat exchanger 122,
it is preferred to dry the coal or to heat exchange the media
W1 and W1a with the water W2. Note that the water W3 raised
20 in temperature by the heat exchanger 122 as described above
is introduced, for example, to the water supply heater 104
and heated thereby, and then supplied to the boiler 102 as
water W4. Such a use of the exhaust gas may also provide,
like the ninth embodiment, the effective use of the heat energy
25 and an established technology to positively use the low grade
fuel.
30
35
[0161]
In the tenth embodiment, the heat exchange is performed
between the desulfurized exhaust gas and the heat medium, and
the heat-exchanged exhaust gas is discharged into the
atmosphere via the electric dust collector 107. After the
desulfurized exhaust gas is supplied in the dust collection
means in advance and the ash content contained in the exhaust
gas is removed, the heat exchange may be performed between
the exhaust gas and the heat medium.
[0162]
49
5
10
[Eleventh Embodiment]
FIG. 18 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to an eleventh
embodiment of the present invention. With reference to FIG.
18, the method for utilizing of exhaust gas according to the
eleventh embodiment is applied to the drying process facility
300 mainly for drying coal provided as the low grade fuel and
the coal thermal power station 100 using the dried coal
supplied from the drying process facility 300 for the
combustion.
30
15
25
20
[0163]
The coal thermal power station 100 comprises the
denitrification device 105, the heat recovery device 106, the
mixing device 112, the electric dust collector 107, and the
desulfurization device 108. Note that in the eleventh
embodiment, the coal thermal power station 100 is configured
to comprise the cement manufacture facility 200 provided along
with it. Heat gas is mixed with exhaust gas from the boiler
102 by the mixing device 112, and then used to dry coal in
the drying process facility 300. This provides a
configuration that may totally perform the effective use of
the heat energy of the exhaust gas.
[0164]
Meanwhile, the exhaust gas generated in the boiler 102
is discharged at a temperature of, for example, about 500 0 e
to 1000 o e, and then has its nitrogen oxide (NOx) removed by
the denitrification device 105 in the subsequent stage. Then,
the exhaust gas is heat exchanged with the air or the like
and thus reduced in temperature by the heat recovery device
106 such as the gas air heater (GAH) provided as the exhaust
gas temperature reduction means.
[0165]
In the eleventh embodiment, the exhaust gas after
passing through the heat recovery device 106 is supplied to
35 the mixing device 112. The exhaust gas has, for example a
temperature of about 90 °e and an oxygen concentration of about
5
10
15
20
25
30
35
50
5 vol%. The mixing device 112 is also provided with heat gas
discharged from the clinker cooler 203 in the cement
manufacture facility 200.
[0166]
The heat gas has, for example, a temperature of about
300°C and an oxygen concentration of about 21 vol%. The mixing
device 112 has a not-shown configuration comprising a control
valve and a control device for controlling the gas mixing,
a gas line, or the like. Then, the mixing device 112 mixes
the exhaust gas and heat gas to generate mixed gas having a
temperature of 150°C or more, preferably 200°C or more, and
an oxygen concentration of 10 vol% or less. The mixing device
112 then supplies the generated mixed gas to the drying process
facility 300.
[0167]
Specifically, the mixing device 112 mixes, for example,
a 68.7 amount (%) exhaust gas having a temperature of 90°C
and an oxygen concentration of 5 vol% and a 31.3 amount (%)
heat gas having a temperature of 300°C and an oxygen
concentration of 21 vol%. Thus, mixed gas having a
temperature 156°C and an oxygen concentration of 10 vol% is
generated. Note that in the drying process facility 300,
drying air having a too high temperature (i.e., drying air
having a temperature higher than the temperature of the firing
point of coal) or drying air having a too high oxygen
concentration both increases the possibili ty of the ignition
or the like.
[0168]
Thus, the mixing device 112 generates mixed gas having
a temperature and an oxygen concentration appropriate for
drying coal, and supplies the mixed gas to the drying process
facility 300 as the drying air. For example, the mixing device
112 generates mixed gas having a temperature of 156°C and an
oxygen concentration of 10 vol% or less, and then the mixed
gas is sent to the drying process facility 300 and used therein
for drying coal, and after the drying process, the mixed gas
51
has a temperature of about 70°C.
[0169]
5
10
15
20
25
In this way, the heat energies of the above exhaust gas
and heat gas may be effectively used wi thout being uselessly
wasted. In other words, the mixed gas may be used in the drying
process, thus achieving the effective heat use in the drying
process facility 300, which may provide the size reduction
and cost reduction of the drying process facility 300.
[0170]
A portion of the exhaust gas that is not mixed with the
heat gas by the mixing device 112 is supplied to the electric
dust collector 107 such as a low temperature electric dust
collector (EP). Then, after passing through the electric
dust collector 107, the exhaust gas has its sulfur oxide (SOx)
removed by the desulfurization device 108, and then discharged
into the atmosphere as exhaust gas. By the above process,
the coal thermal power station 100 generates electricity.
[0171]
Note that the method for utilizing of exhaust gas
according to the eleventh embodiment may be configured to use,
as the drying air to the drying process facility 300 for drying
coal to be supplied to the coal thermal power station 100,
both of the exhaust gas from the boiler 102 and the heat energy
of the heat gas supplied from the cement manufacture facili ty
200 provided along with the power station 100, thus providing
the effective use of the heat energy.
[0172]
Further, the method for utilizing of exhaust gas
according to the eleventh embodiment is configured to be able
30 to use the heat gas from the clinker cooler 203 and the exhaust
gas from the boiler 102 in the drying process in the drying
process facility 300.
[0173]
Specifically, the heat gas discharged from the clinker
35 cooler 203 in the cement manufacture facility 200 is
introduced to the mixing device 112 in the coal thermal power
5
10
15
20
25
30
35
52
station 100, which mixes the heat gas with the exhaust gas
from the boiler 102. Then, mixed gas having an oxygen
concentration of 10 vol% or less is generated and supplied
to the drying process facility 300. Therefore, the method
for utilizing of exhaust gas according to the eleventh
embodiment may provide the effective use of the heat energy
and an established technology to positively use the low grade
fuel.
[0174]
[Twelfth Embodiment]
FIG. 19 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a twelfth embodiment
of the present invention. With reference to FIG. 19, the
method for utilizing of exhaust gas according to the twelfth
embodiment is different from the method according to the
eleventh embodiment in that the exhaust gas to be mixed with
the heat gas from the clinker cooler 203 by the mixing device
112 is exhaust gas passing through the heat recovery device
106 and the electric dust collector 107 by which the exhaust
gas has its temperature reduced and its ash content (dust)
removed, respectively.
[0175]
Specifically, the exhaust gas from the boiler 102 is
reduced in temperature by the heat recovery device 106, and
then supplied to the electric dust collector 107 that removes
the ash content in the exhaust gas. Then, the exhaust gas
from the electric dust collector 107 and the heat gas from
the clinker cooler 203 are introduced to the mixing device
112 to generate mixed gas having a predetermined temperature
and an oxygen concentration as described above. The mixed
gas is then supplied to the drying process facility 300. This
may also provide, like the eleventh embodiment, the effective
use of the heat energy and an established technology to
positively use the low grade fuel. This may also provide the
optimized operations of each device and each process in the
coal thermal power station 100.
5
10
15
20
25
30
35
53
[0176]
[Thirteenth Embodiment]
FIG. 20 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to thirteenth
embodiment of the present invention. FIG. 21 shows the
detailed configuration of FIG. 20. With reference to FIG.
20 and FIG. 21, the method for utilizing of exhaust gas
according to the thirteenth embodiment is different from the
method according to the eleventh embodiment in that instead
of the desulfurization device 108 of the coal thermal power
station 100, the desulfurizing agent supply device 10 is
provided to desulfurize the exhaust gas in the combustion
furnace 20 of the boiler 102 (internal furnace
desulfurization) . A desulfurization facility may be
provided in the subsequent stage.
[0177]
The desulfurizing agent 15 may be injected into the
vicinity position of the upper nose section 21 as described
above, thus performing the efficient desulfurization in the
combustion furnace 20 and decreasing the usage of the
desulfurizing agent 15. After having its S02 and S03 removed
in the combustion furnace 20 as described above, the exhaust
gas is discharged from the combustion furnace 20 through the
flue 22. Then, after, for example, passing through the above
denitrification device 105 to be denitrified and passing
through the heat recovery device 106 to be reduced in
temperature (the temperature is reduced), the exhaust gas is
introduced in the mixing device 112.
[0178]
In the thirteenth embodiment, it is preferable that the
desulfurizing agent 15 injected into the vicinity of the upper
nose portion 21 in the combustion furnace 20 removes S03 in
exhaust gas in advance. Thus, the sulfuric acid dew point
of the exhaust gas may be drastically reduced. The inventors
have demonstrated that specifically, the exhaust gas may thus
be cooled to a temperature of, for example, about 90°C by the
5
10
15
20
25
30
35
54
heat recovery device 106, thereby increasing the heat recovery
amount and thus significantly improving the energy
efficiency.
[0179]
Further, as described above, each device such as the
mixing device 112 may not be made of expensive corrosion
resistant materials. For example, the material of portions
in contact with the exhaust gas, such as the control valve
and the conduit in the mixing device 112, may be made of an
inexpensive carbon steel (carbon steel) material, or the like.
In the method for utilization of exhaust gas according to the
thirteenth embodiment, the desulfurizing agent 15 injected
into the vicinity position of the upper nose section 21 in
the combustion furnace 20 removes S03.
[0180]
Then, the heat recovery device 106 is provided between
the combustion furnace 20 and the collection device 109 to
reduce the temperature of the exhaust gas discharged from the
combustion furnace 20. The concentration of S03 in the
exhaust gas may thus not be enough to affect the collection
performance of the electric dust collector, thereby
maintaining and improving the collection performance.
[0181]
[Fourteenth Embodiment]
FIG. 22 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a fourteenth
embodiment of the present invention. FIG. 23 shows the
detailed configuration of FIG. 22. With reference to FIG.
22 and FIG. 23, the method for utilizing of exhaust gas
according to the fourteenth embodiment is different from the
method according to the twelfth embodiment in that instead
of the desulfurization device 108 of the coal thermal power
station 100, the desulfurizing agent supply device 10 is
provided to perform the internal furnace desulfurization of
the exhaust gas in the combustion furnace 20 of the boiler
102.
5
10
15
20
25
30
55
[0182]
Note that the desulfurization process of the exhaust gas
in the combustion furnace 20 of the boiler 102 is similar to
that described above, and thus further description is omitted
here. This may also provide, like the twelfth embodiment,
the effective use of the heat energy and an established
technology to positively use the low grade fuel. This may
also provide the optimized operation of each device and each
process in the coal thermal power station 100.
[0183]
[Fifteenth Embodiment]
FIG. 24 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to a fifteenth
embodiment of the present invention. With reference to FIG.
24, the method for utilizing of exhaust gas according to the
fifteenth embodiment is applied to the drying process facili ty
300 mainly for drying coal provided as the low grade fuel and
the coal thermal power station 100 using the dried coal
supplied from the drying process facility 300 for the
combustion.
[0184]
The coal thermal power station 100 comprises the
denitrification device 105, an air preheater 106a, the
electric dust collector 107, and the desulfurization device
108. The denitrification device 105 may be arbitrarily
installed. Note that in the fifteenth embodiment, the coal
thermal power station 100 is configured to comprise the cement
manufacture facility 200 provided along with it. Heat gas
is introduced in the boiler 102 as a portion of the combustion
air and is used for the combustion therein. Preferably, the
ratio of the heat gas as the combustion air introduced in the
boiler 102 is about 10% to 25%.
[0185]
The exhaust gas from the boiler 102 is also distributed
35 by, for example, the distribution device 111, and used to dry
coal in the drying process facility 300. The exhaust gas may
5
10
56
be used for drying grinding coal in the grinding device 101.
This provides a configuration that may totally perform the
effective use of the heat energy of the exhaust gas.
[0186]
Note that a portion of the dried coal may be used in a
heat-using facility (for example, the cement manufacture
facility 200) other than the boiler 102. The ground coal is
combusted along with an oxygen-containing gas and the above
heat gas in the combustion furnace 20 of the boiler 102 (for
example, see FIG. 26). Note that the heat gas introduced in
the boiler 102 has, for example, an oxygen concentration of
15 vol% or more and a temperature of 250°C or more.
[0187]
Meanwhile, the exhaust gas generated in the boiler 102
15 is discharged at a temperature of, for example, about 300°C
to 400°C, and then distributed by the distribution device 111
in the subsequent stage. The distribution device 111
comprises a not-shown control valve and a conduit, and
distributes and supplies some of the exhaust gas to the drying
20 process facility 300 and the grinding device 101. Further,
the rest of the exhaust gas has its nitrogen oxide (NOx)
removed by the denitrification device 105.
[0188]
In the fifteenth embodiment, the exhaust gas distributed
25 by the distribution device 111 and supplied to the drying
process facility 300 has an oxygen concentration of, for
example, 10 vol%. Further, after passing through the
denitrification device 105, the exhaust gas is introduced in
the air preheater 106a, where the exhaust gas is used to heat
30 the air, and is then supplied to the electric dust collector
107. After being heated by the air preheater 106a, the heated
air is introduced to the boiler 102. Note that in the drying
process facility 300, exhaust gas used as the drying air having
too high temperature (i.e., drying air having a temperature
35 higher than the temperature of the firing point of coal) or
exhaust gas having a too high oxygen concentration increases
5
10
15
20
25
30
35
57
the possibility of the ignition or the like.
[0189]
Thus, the heat gas from the clinker cooler 203 that has
a high oxygen concentration and a high temperature is not
directly introduced to the drying process facility 300.
Instead, the heat gas is reduced in oxygen concentration in
the boiler 102 and then discharged as the exhaust gas, and
a portion of the heat gas is supplied to the drying process
facility 300 as the drying air. For example, the exhaust gas
having a temperature of 378°C and an oxygen concentration of
10 vol% or less at the distribution device 111 is sent to the
drying process facility 300, where the exhaust gas is used
for drying coal. The exhaust gas after the drying process
has a temperature of about 70°C.
[0190]
As described above, the heat energy of the above exhaust
gas and heat gas may be effectively used without being
uselessly wasted. In other words, the heat gas may be used
in the combustion in the boiler 102 as a portion of the
combustion air, thus eliminating the necessity of providing
a separate heat recovery device to raise the temperature of
the external air and of using the air as the combustion air,
thereby increasing the energy efficiency and decreasing the
facility cost.
[0191]
Further, the exhaust gas after the combustion in the
boiler 102 may be used in the drying process in the drying
process facility 300 to provide the effective use of the heat
in the drying process facility 300 as well as the size
reduction and cost reduction of the drying process facility
300. Therefore, the fifteenth embodiment may provide the
effective use of the heat energy. Note that the exhaust gas
after passing through the air preheater 106a is supplied to
the electric dust collector 107.
[0192]
Note that the method for utilizing of exhaust gas
5
10
15
20
25
30
35
58
according to the fifteenth embodiment uses, as the drying air
to the drying process facility 300 for drying coal to be
supplied to the coal thermal power station 100, the exhaust
gas from the boiler 102. Further, the method according to
the fifteenth embodiment may also be configured to use, as
the combustion air to the boiler 102, the heat gas supplied
from the cement manufacture facility 200 provided along with
the power station 100 and the heated air from the air preheater
106a, thus providing the effective use of the heat energy.
[0193]
The clinker cooler 203 in the cement manufacture
facility 200 discharges, as described above, heat gas having
a temperature of 250°C or more, for example, about 300°C and
an oxygen concentration of 15 vol% or more. However, the heat
energy of the heat gas has been unused and almost just
discharged, as described above. Thus, the method for
utilizing of exhaust gas according to the fifteenth embodiment
may be configured to use the heat gas in the combustion process
in the boiler 102 and the exhaust gas from the boiler 102 in
the drying process in the drying process facility 300.
[0194]
Specifically, the heat gas discharged from the clinker
cooler 203 in the cement manufacture facility 200 is
introduced in the boiler 102 of the coal thermal power station
100 for the combustion. Then, the exhaust gas from the boiler
102 having an oxygen concentration of 10 vol% or less is
supplied to the drying process facility 300 via the
distribution device 111. Therefore, the method for utilizing
of exhaust gas according to the fifteenth embodiment may
provide the effective use of the heat energy and an established
technology to positively use the low grade fuel.
[0195]
Further, the exhaust gas supplied to the drying process
facility 300 may be distributed and supplied from a desired
location as appropriately such as a location after the
denitrification device 105 in the subsequent stage of the
5
15
10
59
boiler 102, a location after the electric dust collector 107,
or a location after the desulfurization device 108. In this
case, the distribution device 111 may be installed between
each device.
[0196]
[Sixteenth Embodiment]
FIG. 25 is a block diagram of the entire flow of a method
for utilizing of exhaust gas according to the sixteenth
embodiment of the present invention. FIG. 26 shows the
detailed configuration of FIG. 25. With reference to FIG.
25 and FIG. 26, the method for utilizing of exhaust gas
according to the sixteenth embodiment is different from the
method according to the fifteenth embodiment in that the coal
thermal power station 100 comprises the desulfurizing agent
supply device 10 to perform the desulfurization of the exhaust
gas in the combustion furnace 20 of the boiler 102 (internal
furnace desulfurization).
[0197]
The sixteenth embodiment is also different from the
20 fifteenth embodiment in that the distribution device 111 is
provided in the subsequent stage of the air preheater 106a,
and the heat recovery device 106 is provided in the subsequent
stage of the distribution device 111. In this way, the method
according to the sixteenth embodiment may provide a more
25 optimized operation of each device and each process in the
coal thermal power station 100 than the method according to
the fifteenth embodiment. Depending on the amount of the heat
gas, the combustion air may be converted to the heat gas up
to the total amount of the combustion air. The preheat of
30 the exhaust gas at the outlet of the air preheater 106a may
be recovered, after passing through the distribution device
111, by the heat recovery device 106, and then be used by the
water supply heater 104 to heat the water supply up to the
total amount of the heat.
35 [0198]
After having its S02 and S03 removed in the combustion
5
10
15
20
25
30
35
60
furnace 20, the exhaust gas is discharged from the combustion
furnace 20 through the flue 22. Then, after, for example,
the exhaust gas passes through the above denitrification
device 105 and is denitrified therein, some of the exhaust
gas is sent to the drying process facili ty 300 by the
distribution device 111 in the subsequent stage of the air
preheater 106a. Further, the rest of the exhaust gas passes
through the heat recovery device 106 that recovers its heat,
and is then sent to the electric dust collector 107.
[0199]
In the sixteenth embodiment, it is preferable that the
desulfurizing agent 15 injected into the vicinity position
of the upper nose section 21 in the combustion furnace 20
removes S03 in the exhaust gas in advance. The inventors have
demonstrated that the sulfuric acid dew point of the exhaust
gas may thus be drastically reduced, thereby increasing the
heat recovery amount and thus significantly improving the
energy efficiency.
[0200]
Further, as described above, each device in the
subsequent stage of the combustion furnace 20 may not be made
of expensive corrosion resistant materials. For example, the
material of portions in contact with the exhaust gas may be
made of an inexpensive carbon steel (carbon steel) material,
or the like. In the method for utilizing of exhaust gas
according to the sixteenth embodiment, the desulfuri zing
agent 15 injected into the vicinity position of the upper nose
section 21 in the combustion furnace 20 removes S03.
[0201]
Therefore, the reduction of the temperature of the
exhaust gas discharged from the combustion furnace 20, which
is the above (1) element of the collection performance of the
electric dust collector, may reduce the volume of the exhaust
gas and also reduce the flow rate of the exhaust gas. Thus,
the concentration of S03 in the exhaust gas may not be enough
to affect the collection performance of the electric dust
5
10
15
61
collector, thereby maintaining and improving the collection
performance. Note that the exhaust gas discharged from the
electric dust collector 107 is desulfurized again by the
desulfurization device 108 if necessary, and then transferred
by the blower 48 and discharged into the atmosphere through
the stack 49.
[Examples]
[0202]
with reference to some examples, the desulfurization
process of the exhaust gas will be specifically described
below. In the examples, the boiler 102 in the coal thermal
power station 100 shown in FIG. 8 or the like is a boiler having
a vapor generation amount of 80 t/h. Coal (pulverized coal)
used as the fuel is supplied to the boiler 102 along with the
air.
[0203]
The used desulfurizing agent 15 is cement factory dust
recovered from the cyclone exhaust gas of the mill 201 of the
above described cement manufacture facili ty 200. A chemical
20 composi tion of the cement plant dust is measured by the X-ray
Fluorescence Analysis. The measurement resul t shows that CaO
has 60.6 mass%, Si02 has 20.8 mass%, and A1203 has 10.3 mass%
by mass. Further, the used cement plant dust has a mass based
average particle size of about 2pm.
25 [0204]
In the following examples 1 and 2, the inj ecting posi tion
of the desulfurizing agent 15 is at ex inside the furnace. In
the example 3, the injecting position of the desulfurizing
agent 15 is at 13 inside the furnace. The inj ecting posi tions
30 at ex in the furnace comprises 4 positions of A, B, C, and 0
that are at a height 0.8 M above a vertex of the nose section
21 shown in FIG. 27 (a) (a vertex of a triangle of the nose
section 21 in FIG. 8 or the like), and 3 positions of E, F,
and G that are at a height 0.4 L below the vertex of the nose
35 section 21 shown in FIG. 27 (b) (total of 7 positions).
[0205]
62
On the other hand, the injecting positions at ~ in the
furnace comprises 3 positions of E, F, and G that are at a
height 0.4 L below the vertex shown in FIG. 27(b). In FIG.
27 (a), the desulfurizing agent 15 is supplied avoiding
5 positions where the overheater 20b is present. Band C in
FIG. 27 (a) are positioned intermediate between a central point
and end points of a side surface. Moreover, E, F, and G in
FIG. 27 (b) are positioned at respective center-line portions
of each of side surfaces of the combustion furnace 20.
10 [0206]
The table 1 below shows S03 measurement resul ts obtained
in the examples. Note that S03 is measured at an inlet of the
electric dust collector 107.
[0207]
15 [Table 1]
~ Desulfurizing Agent SOx S03
Blowing
Concentration Concentration
Type Position Ca/S (ppm) (ppm)
Example 1
Inside of
0.93 200 Less Than 0.05
Example 2 Cement furnace a
Plant Dust 2.06 180 Less Than 0.05
Example 3
fuInrnsiadceeo{f3 2.92 150 Less Than 0.05
[0208]
(Example 1)
In the example 1, the cement plant dust was inj ected into
20 the furnace with such that an SOx concentration of S02 + S03
within the combustion furnace 20 was 200 ppm, and a Ca/S molar
ratio was 0.93. As a result, the S03 concentration was less
than 0.05 ppm.
[0209]
25 (Example 2)
In the example 2, when an SOx concentration within the
combustion furnace 20 was 180 ppm and a Ca/S molar ratio of
the cement plant dust injected into the furnace was 2.06, an
S03 concentration was less than 0.05 ppm similarly to in the
5
10
15
20
25
30
35
63
example 1.
[0210]
(Example 3)
In the example 3, when an SOx concentration within the
combustion furnace 20 was 150 ppm and a Ca/S molar ratio of
the cement factory dust injected into the furnace was 2.92,
an S03 concentration was less than 0.05 ppm similarly to in
the examples 1 and 2. Note that in each of the examples 1,
2, and 3, when the cement plant dust was not injected into
the combustion furnace 20, the SOx concentrations in the
furnace 20 were the same as respective concentrations before
the desulfurization.
[0211]
Using the above results, estimation of the heat balance
revealed that the fuel treatment system 1 and the method for
utilizing of exhaust gas according to the above embodiments
might reduce the sulfuric acid dew point of the exhaust gas
to be set from about 126°C to less than 88°C. It was then
revealed that the corrosion due to S03 condensation might be
suppressed even if, for example, the gas-water heat exchanger
121 as the first heat-exchange means of the indirect heat
exchange mechanism 110 downstream of the heat recovery device
106 shown in FIG. 9 recovered heat corresponding to 50 °C from
the exhaust gas having a temperature of about 150°C when
passing through the heat recovery device 106, and the heat
exchanger 122 as the second heat-exchange means used the heat
as the preheating source of the water W2 to the boiler 102.
It was also confirmed that the corrosion due to the S03
condensation might be suppressed even if, for example, the
heat of the exhaust gas was used by the drying process facility
300 or used to heat the water supply to the boiler 102. It
was also revealed that the corrosion due to the S03
condensation might be suppressed even if, for example, the
mixed gas was generated by the mixing device 112 downstream
of the heat recovery device 106, and then used by the drying
process facility 300. It was also revealed that the corrosion
5
10
15
64
due to the S03 condensation might be suppressed even if, for
example, a portion of the exhaust gas was used in the drying
process facility 300 downstream of the boiler 102.
[0212]
Therefore, the heat exchange process by the indirect
heat exchange mechanism 110 in FIG. S was performed. As heat
medium, deionized water was used. The heat medium
circulation amount was SO tlh (for a boiler at the level of
the main steam generation amount of SO t/h). Exhaust gas was
reduced in temperature from 150°C to 100°C by the gas-water
heat exchanger 121 as the first heat-exchange means. The
deionized water was raised in temperature from 55°C to 74°C
by the gas-water heat exchanger 121. The deionized water as
the heat medium heated by the gas-water heat exchanger 121
raised the temperature of the boiler water supply W2 from 4SoC
to 62.5 °c in the heat exchanger 122 as the second heat-exchange
means.
[0213]
As described above, the treatment system 1 according to
20 the above embodiment may provide the effective use of the heat
energy and the positive use of the low grade fuel.
[0214]
The treatment system 1 according to the above
embodiments may also treat S03 in exhaust gas in a less
25 expensive and easier manner, effectively provide the
effective use of the heat energy of the exhaust gas, and
efficiently operate the power generation facility with less
problems such as facility corrosion.
30 Description of reference numerals
[0215]
1 treatment system
2 database (DB)
3 control unit
35 4 adjustment device
10 desulfurizing agent supply device
5
10
15
20
25
30
35
65
13, 48 blower
14 desulfurizing agent injecting inlet
15 desulfurizing agent
20 combustion furnace
20a wall section
20b overheater
21 nose section (upper nose section )
22 flue
30 exhaust gas temperature reduction facility
31 gas air heater
33 water spray device
49 stack
50 circulation path
50A primary circulation path
50B secondary circulation path
51 line
100 coal thermal power station
101 grinding device
102 boiler
103 electric generator
104 water supply heater
105 denitrification device
106 heat recovery device
107 electric dust collector
108 desulfurization device
110 indirect heat exchange mechanism
111 distribution device
112 mixing device
113 mixing facility
121 gas-water heat exchanger
122 heat exchanger
200 cement manufacture facility
201 mill
202 calcination device
203 clinker cooler
204 mixing mill
300
66
drying process facility
Ii.· t
III

5
10
15
20
25
30
35
67
What is Claimed is:
1. A fuel treatment system comprising:
a drying process facility for drying fuel using heat gas;
an adjustment device for adjusting a temperature of the
heat gas and supplying the adj usted gas to the drying process
facility; and
a control uni t for controlling the adj ustment device on
the basis of data relating to a moisture amount and a
temperature of a firing point of the fuel.
2. The fuel treatment system according to claim 1,
further comprising:
a boiler comprising a supply port for supplying fuel,
desulfurizing agent, and oxygen-containing gas and a
discharge port for discharging exhaust gas after the
combustion of the fuel using the oxygen-containing gas;
a first heat-exchange device for exchanging heat between
the exhaust gas discharged from the boiler and heat medium
to heat the heat medium using the exhaust gas;
a second heat-exchange device for exchanging heat
between water supplied to the boiler and heated heat medium
after the heat exchange to heat the water using the heated
heat medium; and
a circulation pa th through which the heat medi urn passes,
the circulation path circulating between the first
heat-exchange device and the second heat-exchange device.
3. The fuel treatment system according to claim 1 or
2, wherein
the adjustment device adjusts, in addition to a
temperature of the heat gas, a flow rate of the heat gas.
4. The fuel treatment system according to anyone of
claims 1 to 3, wherein
the adjustment device is a heat exchanger.
5. The fuel treatment system according to claim 4,
wherein
the heat exchanger is a boiler water supply heater.
6. The fuel treatment system according to claim 4 or
5
10
15
68
5, wherein
the adjustment device further comprises a distribution
device for distributing the heat gas to the heat exchanger
and a bypass path, and a mixing device for mixing heat gas
discharged from the heat exchanger and heat gas passing
through the bypass path.
7. The fuel treatment system according to anyone of
claims 1 to 6, further comprising,
a thermal power facility for generating electricity by
combusting the fuel dried us ing the drying process facility,
wherein
the thermal power facility comprises:
a combustion furnace for combusting the fuel; and
a desulfurizing agent injecting device provided to the
combust ion furnace for inj ect ing desul furi zing agent into the
combustion furnace.
8. The fuel treatment system according to claim 2,
wherein
in the first heat-exchange device, the circulation path
20 in contact with the exhaust gas has a surface temperature
higher than a dew-point of the exhaust gas.
9. The fuel treatment system according to claim 2 or
8, wherein
the boiler comprises:
25 a combustion furnace for combusting fuel;
a nose section provided in an upper side of an interior
of the combustion furnace for narrowing an internal space of
the combustion furnace, and wherein
the supply port for supplying desulfurizing agent is
30 located in the vicinity of the nose section.
10. The fuel trea tment system according to anyone of
claims 2, 8, and 9, wherein
the desulfurizing agent is calcium compound, and the
calcium compound includes cement plant dust containing
35 calcium carbonate.
11. A method for utilizing of exhaust -gas, comprising,
5
10
15
20
25
30
35
69
supplying coal in a drying process facility to dry the
coal, the coal containing moisture and sulfur component,
supplying the dried coal in a combustion furnace to
combust the coal, and
using heat of exhaust gas after the combustion,
the method further comprising,
supplying desulfurizing agent in the combustion furnace
to desulfurize the exhaust gas in the combustion furnace, and
using heat of the desulfurized exhaust gas as a heat
source for drying the coal.
12. A method for utilizing of exhaust gas, comprising,
supplying coal in a drying process facility to dry the
coal, the coal containing moisture and sulfur component,
supplying the dried coal in a combustion furnace to
combust the coal, and
using heat of exhaust gas after the combustion, the
exhaust gas containing ash content,
the method further comprising the steps of:
cooling the exhaust gas by an exhaust gas temperature
reduction device;
mixing the cooled exhaust gas and heat gas having a higher
temperature than the cooled exhaust gas to generate mixed gas;
and
supplying the mixed gas in the drying process facility,
wherein
the mixed gas is generated at an oxygen concentration
of 10 vol% or less.
13. A method for utilizing of exhaust gas, comprising,
supplying coal in a drying process facility to dry the
coal, the coal containing moisture,
supplying the dried coal in a combustion furnace to
combust the coal, and
using heat of exhaust gas after the combustion,
the method further comprising the steps of:
supplying heat gas discharged from a heat-using facili ty
other than the combustion furnace to the combustion furnace
5
10
15
20
25
30
35
70
as combustion air, the heat gas containing oxygen; and
supplying the exhaust gas to the drying process facility,
wherein
the heat gas has an oxygen concentration of 15 vol% or
more and a temperature of 250°C or more.
14. The method for utilizing of exhaust gas according
to claim 11, wherein
the desulfurized exhaust gas is supplied to the drying
process facility to use heat of the exhaust gas as a heat source
for drying the coal.
15. The method for utilizing of exhaust gas according
to claim 11, wherein
heat is exchanged between the desulfurized exhaust gas
and heat medium, and the heat medium heated by the exhaust
gas is supplied to the drying process facility to use the heat
medium as a heat source for drying the coal.
16. The method for utilizing of exhaust gas according
to anyone of claims 11, 14, and 15, wherein
the desulfurized exhaust gas is supplied to a dust
collection device to remove ash content contained in the
exhaust gas, and heat of the exhaust gas having the ash content
removed is used as a heat source for drying the coal.
17. The method for utilizing of exhaust gas according
to claim 12, further comprising the step of removing the ash
content from the cooled exhaust gas with a dust collection
device , wherein
the mixed gas is generated by mixing the exhaust gas
having the ash content removed and the heat gas.
18. The method for utilizing of exhaust gas according
to claim 13, wherein
the exhaust gas has an oxygen concentration of 10 vol%
or less.
19. The method for utilizing of exhaust gas according
to anyone of claims 12, 13, 17, or 18, wherein
the heat gas is heat gas discharged from a clinker cooler
of a cement manufacture facility.
5
10
71
20. The method for utilizing of exhaust gas according
to anyone of claims 12, 13, and 17 to 19, further comprising
the step of supplying desulfurizing agent in the combustion
furnace to desulfurize exhaust gas in the combustion furnace.
21. The method for utilizing of exhaust gas according
to anyone of claims 11 to 20, wherein
the combustion furnace has, in an upper side thereof,
a nose section for narrowing an internal space of the
combustion furnace, and the desulfurizing agent is supplied
in the vicinity of the nose section.
22. An apparatus for utilizing of exhaust gas,
comprising:
a drying device for drying coal;
a combustion device for combusting the dried coal; and
a desulfurizing agent supply device for supplying
desulfurizing agent to the combustion device, wherein
an exhaust gas supply path is provided connecting the
drying device and the combustion device,
the exhaust gas supply path supplies the desulfurized
exhaust gas to the drying device, and
the drying device dries the coal using heat of the exhaust
gas.