U.S. patent application number 14/119108 was filed with the patent office on 2014-07-24 for method of waste melting treatment.
This patent application is currently assigned to KINKI UNIVERSITY. The applicant listed for this patent is Hajime Akiyama, Tamio Ida, Takashi Nakayama, Takeshi Uchiyama, Tomohiro Yoshida. Invention is credited to Hajime Akiyama, Tamio Ida, Takashi Nakayama, Takeshi Uchiyama, Tomohiro Yoshida.
Application Number | 20140202364 14/119108 |
Document ID | / |
Family ID | 47217279 |
Filed Date | 2014-07-24 |
United States Patent
Application |
20140202364 |
Kind Code |
A1 |
Nakayama; Takashi ; et
al. |
July 24, 2014 |
METHOD OF WASTE MELTING TREATMENT
Abstract
A waste-melting method, in which waste is fed into a
waste-melting furnace (1), and the waste is thermally decomposed
and combusted, and then, thermal decomposition and combustion
residues are melted, is characterized in that coal coke and a
biomass-molded material obtained by press-molding a biomass
starting material while heating the biomass starting material to a
temperature lower than the carbonization temperature thereof are
fed into the melting furnace, a high-temperature grate is formed
with coal coke at the bottom of the melting furnace, and the coal
coke and the biomass-molded material are combusted and used as heat
sources for melting.
Inventors: |
Nakayama; Takashi; (Tokyo,
JP) ; Uchiyama; Takeshi; (Tokyo, JP) ;
Akiyama; Hajime; (Tokyo, JP) ; Yoshida; Tomohiro;
(Tokyo, JP) ; Ida; Tamio; (Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nakayama; Takashi
Uchiyama; Takeshi
Akiyama; Hajime
Yoshida; Tomohiro
Ida; Tamio |
Tokyo
Tokyo
Tokyo
Tokyo
Osaka |
|
JP
JP
JP
JP
JP |
|
|
Assignee: |
KINKI UNIVERSITY
Osaka
JP
JFE ENGINEERING CORPORATION
Tokyo
JP
|
Family ID: |
47217279 |
Appl. No.: |
14/119108 |
Filed: |
May 23, 2012 |
PCT Filed: |
May 23, 2012 |
PCT NO: |
PCT/JP2012/063116 |
371 Date: |
February 17, 2014 |
Current U.S.
Class: |
110/346 |
Current CPC
Class: |
F23G 5/08 20130101; F23G
2202/20 20130101; F23G 5/444 20130101; F23G 5/0276 20130101; F23G
5/165 20130101; F23G 5/24 20130101; F23G 5/027 20130101 |
Class at
Publication: |
110/346 |
International
Class: |
F23G 5/027 20060101
F23G005/027; F23G 5/44 20060101 F23G005/44; F23G 5/08 20060101
F23G005/08 |
Foreign Application Data
Date |
Code |
Application Number |
May 23, 2011 |
JP |
2011-114446 |
Claims
1-5. (canceled)
6. A method of waste melting treatment performed by charging waste
into a waste melting furnace, thermally decomposing and burning the
waste, and melting a pyrolysis combustion residue to produce a
melt, comprising: the biomass molding step of providing a biomass
molded article containing volatile components by 50 weight percent
or more and having a property suppressing pyrolysis and combustion
of the volatile components until the biomass molded article
reaching a lower section of the waste melting furnace after having
been charged into the waste melting furnace, the high temperature
fire grate forming step of forming a high temperature fire grate
with coal coke in the lower section of the melting furnace by
charging the coal coke into the waste melting furnace at a minimum
supply quantity required for forming a high temperature fire grate
securing combustion gas rising and passing through the high
temperature fire grate and the melt falling and passing
therethrough with voids created between lumps of coke, the biomass
molded articles falling step of, after the biomass molded article
provided in the biomass molding step having been charged into the
waste melting furnace, causing the biomass molded article to fall
and reach the high temperature fire grate while suppressing
pyrolysis and combustion of the volatile components of the biomass
molded article, and the pyrolysis combustion residue melting step
of melting the pyrolysis combustion residue, using the heat
generated by burning the coal coke, and the volatile components and
fixed carbon of the biomass molded article with the high
temperature fire grate.
7. The method of waste melting treatment according to claim 6,
wherein the biomass molding step performs heating a biomass raw
material at a temperature of 115 to 230.degree. C. while pressure
molding it.
8. The method of waste melting treatment according to any one of
claims 6 or 7, wherein the biomass molding step provides a biomass
molded article as a prismatic body one side of which has a length
of 50 mm or longer, or a cylindrical body having a diameter of 50
mm or larger and a length of 50 mm or longer.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of waste melting
treatment by thermally decomposing, burning, and melting waste in a
shaft furnace type melting furnace.
BACKGROUND ART
[0002] As the technology for treating waste, such as city garbage
or shredder dust, the method of waste melting treatment that
thermally decomposes and burns the waste, and melts the pyrolysis
residue into slag, discharging it.
[0003] This treating method offers advantages that the waste can be
thermally decomposed to be gasified, thereby allowing the
combustion heat to be recovered, and after melting the pyrolysis
residue and discharging it as slag, the volume of the waste to be
finally disposed can be reduced by making land-filling disposal or
other. Such a melting treatment method is available in several
types, and as one of them, the method is available which uses a
shaft furnace type waste gassification melting furnace, which is of
vertical type.
[0004] This shaft furnace type waste gassification melting furnace
performs such a treatment as that in which the coke deposited in
the lower section of the furnace is burned, and onto such coke at
high temperature, the waste is charged to be thermally decomposed
and partially oxidized for gasification, with the residue being
melted into slag (refer to Patent Document 1).
[0005] With the shaft furnace type waste gassification melting
furnace disclosed in Patent Document 1, the functions of the
furnace body with a vertical and cylindrical shape are basically
divided into three regions along the vertical direction from the
viewpoint of function. In other words, in the lower section of the
furnace, there is formed a high temperature combustion zone having
a coke bed in which the coke is deposited; above this high
temperature combustion zone, a waste layer is formed; and in the
upper section of the furnace body above the waste layer, a
freeboard section having a large space is provided.
[0006] With such a gassification melting furnace, in the respective
three regions mentioned above, oxygen-containing gas is blown into
the furnace. The high temperature combustion zone in the furnace
lower section is provided with a main tuyere, and therethrough
oxygen rich air is blown in order to obtain a melting heat source
for burning the coke charged and deposited in the coke bed to melt
the pyrolysis residue of the waste. In addition, the waste layer is
provided with a sub-tuyere for slowly fluidizing the waste which
has been charged and deposited, and blowing air to thermally
decompose and partially oxidize the waste. Further, the freeboard
section is provided with a third-level tuyere for blowing air to
partially burn the pyrolysis gas (combustible gas) generated with
the waste being thermally decomposed, and thus to maintain the
inside of the furnace at a prescribed temperature.
[0007] Thus, the shaft furnace type waste gassification melting
furnace is a provision which, within a single furnace, can perform
both the pyrolysis gassification treatment and the melting
treatment of the waste as it falls in the furnace. The charged
waste is thermally decomposed, thereby gas and residue being
generated. By blowing oxygen rich air from the main tuyere, the
coke in the coke bed is burned, a high temperature combustion zone
being formed, and the pyrolysis residue of the waste is melted to
be discharged as slag and metal. The high temperature gas generated
by the coke combustion in the high temperature combustion zone
heats the waste in the waste layer formed above the high
temperature combustion zone, the waste being thermally decomposed
with the air being blown from the sub-tuyere, and the gas
containing combustible gas generated by such pyrolysis rises in the
waste layer, passing through the freeboard section, to be
discharged from a discharge flue provided in the upper section of
the furnace into a secondary combustion chamber outside the
furnace. The gas, containing a large quantity of combustible gas,
is burned in the secondary combustion chamber, the heat being
recovered at a boiler to generate steam, which is used for electric
power generation, or the like. The gas discharged from the boiler
is removed of relatively coarse dust particles by means of a
cyclone separator; then is cooled by a temperature lowering
apparatus; is removed of noxious gas through reaction with a
harmful substance removing agent; and is subjected to an exhaust
gas treatment, such as that for dust removal with a dust collector,
being dissipated to the atmosphere from a smoke stack.
[0008] With such a waste gassification melting furnace, a coke bed
in which coke is deposited is formed in the furnace bottom section,
and the coke is burned to provide a heat source for melting the
pyrolysis residue, however, in recent years, there has been a
demand for reducing the quantity consumed of coal coke originating
from the fossil fuel to cut the carbon dioxide emission amount.
Then, in order to cut the quantity consumed of coke, there have
been proposed a waste melting method which, as an alternative to
coal coke, utilizes lumpy biomass, such as a carbide produced by
heating and pressure molding of sawdust available as a building
waste material for carbonizing it, or charcoal (refer to Patent
Document 2), and another method which charges a biomass solid
substance, such as a briquette produced by pressure molding of
biomass, into a waste gassification melting furnace for converting
it into a carbide within the furnace to form a carbide layer (refer
to Patent Document 3).
CITATION LIST
Patent Literature
[0009] Patent Document 1: Japanese Unexamined Patent Application
Publication No. 09-060830
[0010] Patent Document 2: Japanese Unexamined Patent Application
Publication No. 2005-249310
[0011] Patent Document 3: Japanese Unexamined Patent Application
Publication No. 2005-274122
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0012] Even if, as an alternative to coke, lumpy biomass of a
carbide or a biomass solid substance is utilized as proposed in
Patent Document 2 or 3 for reducing the quantity consumed of coke
in the waste melting furnace to thereby cut the carbon dioxide
emission amount and reduce the cost for operating the waste melting
furnace, there will be presented the following problems. In other
words, in the case where, as is disclosed in Patent Document 2,
lumpy biomass of a carbide is utilized, or as is disclosed in
Patent Document 3, a biomass solid substance is charged into the
waste melting furnace to convert it into a carbide within the
furnace, the combustion heat of the volatile components possessed
by a biomass raw material is consumed in the course of
carbonization, the thermal energy corresponding to the fixed carbon
in the biomass raw material being used as a melting heat source as
an alternative to the melting heat source given by the coke.
Therefore, for the quantity of coal coke that is to be cut, it
becomes necessary to charge a large quantity of lumpy biomass of a
carbide or a biomass solid substance, and since these are
expensive, as compared to the coal coke, the expense required for
cutting the quantity consumed of coal coke is increased, thereby
the cost for operating the waste melting furnace being increased,
which is a problem. Another problem is that the combustion heat of
the volatile components possessed by the biomass raw material could
have not been effectively utilized. Another problem is that the
lumpy biomass of a carbide or the carbide produced by the biomass
solid substance being carbonized within the furnace is poor in
stability as a high temperature fire grate, compared to the coal
coke, thereby a temperature decrease in the lower section of the
melting furnace or a discharge failure of molten slag being caused
and thus the operation becoming unstable.
[0013] In view of the above-mentioned problems, the present
invention has been made, and it is an object thereof to provide a
method of waste melting treatment that can reduce the quantity
consumed of coal coke in a waste melting furnace to cut a carbon
dioxide emission amount, suppressing the cost for operating the
waste melting furnace from being increased, and allowing the
combustion heat of the volatile components possessed by a biomass
raw material to be effectively utilized, and a more stable
operation to be performed.
Means for Solving the Problems
[0014] The method of waste melting treatment in accordance with the
present invention charges waste into a shaft furnace type waste
melting furnace for thermally decomposing, burning, and melting the
waste.
[0015] Specifically, the method of waste melting treatment in
accordance with the present invention charges coal coke, and a
biomass molded article produced by heating a biomass raw material
at a temperature lower than the carbonization temperature thereof
while pressure molding it; forms a high temperature fire grate in a
lower section of the melting furnace with the coal coke; and burns
the coal coke and the biomass molded article to provide a melting
heat source.
[0016] Biomass resources have been classified by FAO (Food and
Agriculture Organization of the United nations), and the biomass
resources include woody biomass, such as forest remaining wood,
thinned wood, unutilized tree materials, lumber sawing remaining
materials, and construction scraps; herbaceous biomass, such as
straw, and rice hulls; and further, papermaking biomass;
agricultural residues; and unutilized biomass resources, such as
livestock excreta, and food waste. The present invention uses a
biomass molded article produced by heating such a biomass resource
as a raw material (to be called a biomass raw material) at a
temperature lower than the carbonization temperature thereof while
pressure molding it. In the present specification, the term
"carbonization temperature" refers to a temperature at which the
volatile components of a biomass raw material starts
volatilization, which is also a temperature at which dry
distillation is started.
[0017] The biomass molded article, which is produced by heating a
biomass raw material at a temperature lower than the carbonization
temperature thereof while pressure molding it, contains volatile
components, and therefore, by charging such biomass molded article
into a melting furnace to be burned in the lower section thereof
for use as a melting heat source, the combustion heat of the
volatile components possessed by the biomass raw material can be
effectively utilized.
[0018] In accordance with the present invention having such a
configuration, the coal coke forming a high temperature fire grate
provides a function which assures passing of gas and liquid through
the high temperature fire grate, by creating voids between lumps of
coke, on the basis of its inherent lumpy geometry, and a function
which serves as a heat source for melting. On the other hand, the
biomass molded article can be used regardless of its high
temperature strength, geometry, and dimensions, having a function
as a melting heat source which supplements the heat quantity of the
coal coke for melting. Therefore, as the required quantity of coal
coke, a minimum quantity required for forming a high temperature
fire grate will suffice, and the shortage as the melting heat
source can be supplemented with the above-mentioned biomass molded
article, whereby both can secure a sufficient melting heat source,
while, with a minimum quantity of coal coke, a high temperature
fire grate layer can be formed.
[0019] If only the biomass molded article is to be used to form a
high temperature fire grate, it will be required to provide a
biomass molded article having a high temperature strength and a
size larger than a prescribed one, the cost of which is high. In
addition, the stability thereof as a high temperature fire grate
will be poor as compared to the coal coke. On the other hand, if
the biomass molded article is required to play a role only as a
source for supplying melting heat, in other words, a melting heat
source, it is not required to have a high temperature strength.
Therefore, there is no need for using an expensive biomass carbide,
whereby the cost for operating the waste melting furnace can be
suppressed from being increased.
[0020] Then, if the coal coke is used to form a high temperature
fire grate, the coal coke and the biomass molded article are burned
with the air for combustion being fed from the main tuyere, the
combustion gas well rising and passing through the high temperature
fire grate for heating and thermally decomposing the waste to burn
and melt it, and the melt well falling and flowing through the
above-mentioned high temperature fire grate.
[0021] In the present invention, the biomass molded article is
preferably a molded article containing the volatile components by
50 weight percent or more. By heating the biomass raw material
while pressure molding it so as to provide a molded article
containing the volatile components by 50 weight percent or more,
the combustion heat of the volatile components possessed by the
biomass raw material can be effectively utilized.
[0022] In the present invention, it is preferable that the biomass
molded article be a molded article which is produced by heating the
biomass raw material at a temperature of 115 to 230.degree. C.
while pressure molding it. By heating the biomass raw material at a
temperature of 115 to 230.degree. C. while pressure molding it, a
biomass molded article with which the volatile components possessed
by the biomass raw material are left can be obtained, whereby the
combustion heat of the volatile components possessed by the biomass
raw material can be effectively utilized.
[0023] In the present invention, it is preferable that the biomass
molded article be a prismatic body one side of which has a length
of 50 mm or longer, or a cylindrical body having a diameter of 50
mm or larger and a length of 50 mm or longer. By using a biomass
molded article having such dimensions and a geometry, the biomass
molded article, after having been charged into the melting furnace,
can reach the lower section of the furnace, while the volatile
components being suppressed from being thermally decomposed and
burned in the furnace, whereby the combustion heat of the volatile
components possessed by the biomass raw material can be effectively
utilized as a melting heat source.
[0024] In the present invention, it is preferable that the quantity
of coal coke to be charged into the furnace be at least a quantity
required for forming a high temperature fire grate, and the heat
quantity required to provide a melting heat source be supplemented
by the biomass molded article.
Advantages of the Invention
[0025] As described above, the present invention can provide a
method of waste melting treatment with which, upon making a melting
treatment of waste in a shaft furnace type melting furnace, coal
coke and a biomass molded article are charged, and therefore, in
the furnace, a high temperature fire grate is formed by the coal
coke, whereby, in the state in which the combustion gas rising and
passing through the high temperature fire grate and the melt
falling and flowing through the same are well maintained, the
melting heat source can be secured with a minimum quantity of coal
coke required for forming a high temperature fire grate and the
biomass molded article supplementing the coal coke; the quantity
consumed of coal coke can be reduced to cut the carbon dioxide
emission amount with the cost for operating the waste melting
furnace being reduced; in addition, the combustion heat of the
volatile components possessed by the biomass raw material can be
effectively utilized, and a more stable operation can be carried
out.
BRIEF DESCRIPTION OF THE DRAWING
[0026] FIG. 1 is a figure showing a schematic configuration of an
apparatus of one embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0027] Hereinbelow, an embodiment of the present invention will be
explained with reference to the attached drawing, i.e., FIG. 1. In
the present embodiment, coal coke and a biomass molded article are
supplied to a shaft furnace type waste gassification melting
furnace as fuel, however, prior to explaining such a feature, the
schematic configuration of the shaft furnace type waste
gassification melting furnace will be explained.
[0028] With the shaft furnace type waste gassification melting
furnace shown in FIG. 1 in one embodiment of the present invention,
the upper section of the gassification melting furnace 1 is
provided with a charging port 2 for charging waste as an object to
be treated, coal coke and a biomass molded article as fuel, and
lime stone as a material for adjusting the slag composition into
the furnace, and the side of the upper section is provided with a
gas discharge port 3 for discharging the gas in the furnace to the
outside thereof. In addition, the bottom section of the
gassification melting furnace 1 is provided with a residue
discharge port 4 for discharging the molten slag and the molten
metal.
[0029] With the shaft furnace type waste gassification melting
furnace, the internal space of the gassification melting furnace 1
is basically divided into three regions along the vertical
direction; from bottom, the three regions providing a lower shaft
section I, which is formed in the lower section of the furnace, a
middle shaft section II, which is located above the lower shaft
section I, and a freeboard section III, which is formed in the
upper section. These sections I, II, and III are regions having the
following functions, respectively. In other words, the lower
section shaft section I is a region where the coal coke and biomass
molded article deposited are burned to form a high temperature
combustion zone; the middle shaft section II is a region where the
waste in the waste layer, which is formed by the deposition of the
waste charged onto the high temperature combustion zone, is
thermally decomposed; and the freeboard section III is a region
where the combustible gas generated is partially burned.
[0030] Above the waste gassification melting furnace 1, there is
disposed a supply apparatus (not shown) which supplies waste, such
as municipal waste, coal coke, biomass molded article, and lime
stone for use as a material for adjusting the composition of slag
generated, respectively. The waste, the coal coke and biomass
molded article, and the lime stone are conveyed by a carrying
conveyor (not shown), and charged into the furnace from the
above-mentioned charging port 2 in the furnace upper section.
[0031] On the furnace wall, there are provided tuyeres for blowing
oxygen-containing gas into the respective lower shaft section I,
middle shaft section II, and freeboard section III mentioned above,
which are formed in the waste gassification melting furnace. In
other words, in the lower shaft section I, there is provided a main
tuyere 5 through which oxygen rich air is blown to burn the coal
coke and biomass molded article which have been deposited in the
lower shaft section I for forming a high temperature combustion
zone to melt the pyrolysis residue; in the middle shaft section II,
there is provided a sub-tuyere 6 through which air is blown to
partially burn the charged and deposited waste, and slowly
fluidizing the waste while thermally decomposing and burning it;
and in the freeboard section III, there is provided a third-level
tuyere 7 for blowing air to partially burn the combustible gas
generated by thermally decomposing the waste for maintaining the
inside of the furnace at a prescribed temperature.
[0032] The gas discharge port 3 is connected to a secondary
combustion chamber 10 for burning the combustible gas generated by
thermally decomposing the waste. For secondary combustion, an air
blowing port 11 through which air is blown is provided. In
addition, adjacent to this secondary combustion chamber 10, a
boiler 12 is provided in order to recover the heat from the
combustion gas produced by burning the combustible gas in the
secondary combustion chamber 10.
[0033] On the other hand, the biomass molded article is produced as
a prismatic body one side of which has a length of 50 mm or longer,
or a cylindrical body having a diameter of 50 mm or larger and a
length of 50 mm or longer, by filling a molding container with a
pulverized biomass raw material, and heating it at a temperature of
115 to 230.degree. C., while pressure molding it. By heating and
pressure molding under such a heating condition, the biomass raw
material can be provided as a biomass molded article without being
carbonized, and containing the volatile components by 50 weight
percent or more. The pressure for pressure molding may be 8 to 25
MPa. As the method for biomass molded article manufacturing, the
manufacturing method disclosed in Domestic Re-publication of PCT
International Application No. WO2006/078023 may be applied.
[0034] By performing molding under the above-mentioned heating and
pressure conditions, the biomass molded article can be provided
with a surface which is extremely dense and free from pores. By
using a biomass molded article produced as a prismatic body one
side of which has a length of 50 mm or longer, or a cylindrical
body having a diameter of 50 mm or larger and a length of 50 mm or
longer, and having a surface which is extremely dense and free from
pores, the biomass molded article, after having been charged into
the melting furnace, can reach the lower section of the furnace,
while the volatile components being suppressed from being thermally
decomposed and burned in the furnace, the combustion heat of the
volatile components possessed by the biomass raw material can be
effectively utilized as a melting heat source.
[0035] With the present embodiment apparatus configured as thus,
gasified melting treatment of the waste is performed in the
following manner.
[0036] The waste, the coal coke and biomass molded article, and the
lime stone from the supply apparatus are charged into the furnace
by a prescribed quantity, respectively, through the charging port 2
provided in the upper section of the gassification melting furnace
1, and from the main tuyere 5, the sub-tuyere 6, and the
third-level tuyere 7, oxygen rich air or air is blown into the
furnace, respectively. The waste which has been charged from the
above-mentioned charging port 2 is deposited in the middle shaft
section II in the furnace to form a waste layer, being dried by the
high temperature gas rising from the high temperature combustion
zone in the lower shaft section I and the air blown from the
sub-tuyere before being thermally decomposed. The combustible gas
generated by the pyrolysis is burned in the freeboard section III
with the air blown from the third-level tuyere, being maintained at
a temperature of 850.degree. C. or higher, and after being
subjected to a treatment for decomposing the harmful gas and the
tar component, is fed to the secondary combustion chamber provided
outside the furnace, the heat of the combustion gas being recovered
by the boiler. The coal coke falls to the lower shaft section I;
the biomass molded article falls to the lower section shaft section
I, while the volatile components being suppressed from being
thermally decomposed and burned on the way of falling, as a result,
a high temperature combustion zone is formed, the coal coke and
biomass molded article being burned, the pyrolysis residue which
has been produced as a result of thermal decomposition of the waste
in the waste layer in the middle shaft section II falls and reaches
the lower section shaft section I, where a high temperature
combustion zone is formed, the coal coke and biomass molded article
being burned; and in the lower section shaft section I, the
volatile components in the biomass molded article, and the fixed
carbon in the coal coke and biomass molded article are burned, the
noncombustibles being melted to be changed into molten slag and
molten metal. The molten slag and the molten metal are discharged
from the residue discharge port 4 to be fed to a water granulating
apparatus provided outside of the furnace, and cooled and
solidified, the cooled and solidified water granulated slag and the
water granulated metal being recovered.
[0037] Thus, the coal coke and biomass molded article are charged
into the waste gassification melting furnace; the coal coke forms a
high temperature fire grate in the lower section of the
gassification melting furnace 1; and the coal coke and biomass
molded article are burned to provide a melting heat source for
melting the pyrolysis residue (ash) of the waste, and the
noncombustibles. The quantity of coal coke to be charged into the
furnace is a quantity required for forming a high temperature fire
grate, and the heat quantity necessary as the melting heat source
is supplemented by the biomass molded article, a prescribed
quantity being charged, respectively.
[0038] In such a course of gasified melting treatment of waste, the
coal coke of the coal coke and biomass molded article as fuel has a
lumpy geometry at the beginning of being charged into the furnace,
and in the high temperature combustion zone in the lower shaft
section I, the voids between coal cokes form a high temperature
fire grate. The top face of the layer of the high temperature fire
grate is located above the main tuyere 5; the oxygen rich air or
air from the main tuyere 5 rises and passes through the
above-mentioned voids, the combustion of the coal coke and biomass
molded article being well carried out; and a sufficient quantity of
the combustion gas reaches the waste layer. On the other hand, in
the high temperature combustion zone, the noncombustibles and ash
of the waste are sufficiently melted by the quantity of heat
obtained by the combustion of the coal coke and biomass molded
article, thereby molten slag and molten metal being produced. The
molten slag and the molten metal well fall and pass through the
above-mentioned voids of the high temperature fire grate, reaching
the residue discharge port 4.
[0039] According to such a gasified melting treatment method for
waste, the coal coke forming a high temperature fire grate provides
a function which assures passing of gas and liquid through the high
temperature fire grate, by creating voids between lumps of coke, on
the basis of its inherent lumpy geometry, and a function which
serves as a heat source for melting. On the other hand, the biomass
molded article can be used regardless of its high temperature
strength, geometry, and dimensions, providing a function as a
melting heat source which supplements the heat quantity of the coal
coke for melting. Therefore, as the required quantity of coal coke,
a minimum quantity required for forming a high temperature fire
grate will suffice, and the shortage as the melting heat source can
be supplemented with the above-mentioned biomass molded article,
whereby both can secure a sufficient melting heat source, while,
with a minimum quantity of coal coke, a high temperature fire grate
layer can be formed. If the biomass molded article is required to
play a role only as a source for supplying melting heat, in other
words, a melting heat source, it is not required to have a high
temperature strength. Accordingly, inexpensive biomass molded
article can be used, whereby the cost for operating the waste
melting furnace can be reduced.
[0040] Then, if the coal coke is used to form a high temperature
fire grate, the coal coke in the high temperature fire grate and
the biomass molded article deposited in the high temperature fire
grate are burned with the air for combustion fed from the main
tuyere, the combustion gas well rising and passing through the high
temperature fire grate for heating and thermally decomposing the
waste to burn and melt it, and the melt well falling and flowing
through the above-mentioned high temperature fire grate.
[0041] In this way, with the high temperature fire grate, the
combustion gas rising and passing therethrough and the molten slag
and molten metal falling and flowing therethrough are well
maintained, while the coal coke and the biomass molded article as
fuel being burned. Upon the combustion, as the quantity of coal
coke to be charged, a minimum quantity required for forming a high
temperature fire grate will suffice, and the shortage to the heat
quantity required for gasification melting of the waste is
supplemented with the biomass molded article. Further, the
combustion heat of the volatile components possessed by the biomass
raw material can be effectively utilized as the melting heat
source.
[0042] Thus, the quantity consumed of coal coke can be minimized,
while the biomass molded article can be charged regardless of its
high temperature strength, geometry, and dimensions, and even an
inexpensive biomass molded article can be used as fuel. In this
way, the quantity consumed of coal coke can be reduced to cut the
carbon dioxide emission amount with the cost for operating the
waste melting furnace being reduced, whereby waste treatment
allowing stable operation can be carried out.
[0043] Biomass is preferably molded under the above-mentioned
heating and pressure conditions, and to the above-mentioned
dimensions and geometry, however, heating and pressure molding of
biomass may be performed under other conditions, provided that the
volatile components of the biomass raw material are effectively
left.
DESCRIPTION OF SYMBOLS
[0044] The symbol 1 denotes a gassification melting furnace.
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