Furnaces – Process – Incinerating refuse
Reexamination Certificate
1999-04-07
2001-01-30
Ferensic, Denise L. (Department: 3749)
Furnaces
Process
Incinerating refuse
C110S204000, C110S219000, C110S235000, C110S342000, C110S345000, C110S346000, C110S233000, C060S643000
Reexamination Certificate
active
06178899
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to waste treatment method and waste treatment apparatus capable of effectively obtaining an energy from an industrial waste and municipal or domestic waste particularly by utilizing a technology for improving gasification treatment function and efficiency.
Waste is largely classified into municipal or domestic waste including household waste, so-called urban waste, and industrial waste.
These wastes include various sectors of materials such as paper, fiber, wood, bamboo, rubber, metal, plastic, glass, pottery, soil, sand and the like. A calorific value (heating value) of these wastes is generally calculated to be 4000-5000 kcal on dry basis excluding water content, which corresponds to about ⅔ of the heating value of coal. Therefore, it is considered that the waste is a large energy source.
Recently, various waste treatment (disposal) methods for obtaining energy from the waste have been developed.
For example, Japanese Patent Laid-Open Publication No. HEI 8-24904 and Japanese Patent Laid-Open Publication No.HEI 9-79548 disclose a waste treatment (disposal) method and waste treatment apparatus relating to the waste treatment method.
FIG. 6
is a diagram showing a structure of a conventional waste treatment apparatus.
As shown in
FIG. 6
, the waste treatment apparatus essentially comprises a pyrolysis (thermal decomposition) unit
4
for pyrolysing waste
1
as raw material into pyrolysis gas
2
and solid material
3
, and a mechanical processing unit
5
for crushing the solid material
3
obtained by this pyrolysis unit
4
to fine particles so as to separate metal contained in the solid material
3
, which are processing units on an initial stage. Further, a high temperature gasification unit
10
for converting a pyrolysis char
6
obtained by the mechanical processing unit
5
and pyrolysis gas
2
obtained by the pyrolysis unit
4
to heating gas
9
of low molecular carbide by adding oxidizer
7
and production control char
8
like coke is provided at the post stage.
The pyrolysis unit
4
is provided with a shredder
11
for crushing the waste
1
to fine particles and on the other hand, a secondary side of the high temperature gasification unit
10
is provided with a gas scrubber
12
for removing HCl, HF and dirt. Then, an energy utilization unit
13
for supplying the heating gas
9
and a flue gas desulfurization plant
15
for desulfurizing flue gas
14
are provided on the secondary side of the gas scrubber
12
.
A waste treatment method for treating the waste using the apparatus of the structure mentioned above will be described hereunder.
That is, after the waste
1
essentially consisting of metallic dirt to which organic substance adheres is crushed to fine particles with the shredder
11
, air
16
and energy
17
are supplied to the pyrolysis unit
4
, which is actuated at a temperature of about 550-600° C. so as to separate the pyrolysis gas
2
and solid material
3
. This solid material
3
is crushed by the mechanical processing unit
5
, and metal
18
contained in the solid material
3
is sorted and the metal
18
is removed after washing. On the other hand, after the metal
18
is removed, the pyrolysis char
6
essentially consisting of pyrolysed organic substance and inorganic component is introduced to a high temperature gasification unit
10
together with the pyrolysis gas
2
.
The high temperature gasification unit
10
is operated by supplying an oxidizer
7
and an energy
19
at 1600° C. so as to convert the pyrolysis char
6
and pyrolysis gas
2
to a low molecular heating gas
9
. In this high temperature gasification unit
10
, the inorganic component is converted to part of glass structure
20
through a heating process, and the inorganic component is then removed.
After dirt contained in the heating gas
9
is removed in the gas scrubber
12
, the heating gas
9
is introduced to the energy utilization
13
. Further, the flue gas
14
generated from the energy utilization unit
13
and exhaust gas
21
generated from the pyrolysis unit
4
are introduced into the flue gas desulfurization plant
15
so as to obtain a low temperature clean exhaust gas
22
.
A part of gas
23
purified by removing dirt in the gas scrubber
12
is supplied to the pyrolysis unit
4
. Further, an energy
24
obtained in the high temperature gasification unit
10
and energy utilization unit
13
is used for recycle in other plant.
Although the waste treatment method mentioned above is excellent in such a viewpoint that rough particle incombustible component contained in the waste can be used for recycle, the following problems are contained.
Conventionally, the pyrolysis gas
2
generated by carbonization and the pyrolysis char
6
obtained after the mechanical treatment are introduced to the high temperature gasification unit
10
at the same time and, then, a heating gas
9
is obtained by gas conversions of the pyrolysis gas
2
and pyrolysis char
6
in the high temperature gasification unit
10
. However, it is difficult to satisfy an optimum condition for treating the pyrolysis gas
2
and pyrolysis char
6
at the same time, and as a result, the heating gas
9
cannot be obtained effectively from the pyrolysis gas
6
. That is, there is a problem that gas treatment efficiency is not good.
Further, in the above described conventional waste treatment apparatus, chlorine contained in the waste
1
is combined with oxygen in the pyrolysis unit
4
so that harmful dioxin is generated, which provides a severe problem in viewpoint of environment pollution. Further, because the chlorine and the like are contained in the waste
1
, the pyrolysis apparatus is likely to corroded by these materials, so that the apparatus is likely to be deteriorated.
Although, before the heating gas
9
is supplied to the energy utilization unit
13
, desulfurization or other treatment is desirable in viewpoint of corrosion of the energy supply unit
13
, such a treatment has not been done and therefore, the heating gas
9
obtained from the waste has not been effectively used.
SUMMARY OF THE INVENTION
A primary object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide a waste treatment method for effectively carrying out gas conversion for pyrolysis gas and gasified gas conversion for pyrolysis char separately, in which gas processing efficiency on gas conversion for the pyrolysis gas and gasified gas conversion for the pyrolysis gas is improved.
Another object of the present invention is to provide a waste treatment apparatus for carrying out gas conversion of the pyrolysis gas and pyrolysis char separately to achieve effective waste treatment, the waste treatment apparatus being capable of reducing generation of dioxin and the like which are considered to be harmful by sealing from the air of the atmosphere during the pyrolysis.
A further object of the present invention is to provide a waste treatment method and waste treatment apparatus in which the waste is converted to gas, the gas being subjected to refining (cleaning) treatment and supplied to other equipment or systems to that it is used effectively as electric energy.
These and other objects can be achieved according to the present invention by providing, in one aspect, a waste treatment method comprising:
a pyrolysis step for pyrolysing waste containing organic substance in a condition sealed from an air so as to separate to a pyrolysis gas and a pyrolysis residue;
a gas cracking step for introducing the pyrolysis gas after the pyrolysis step to react an oxide component in the pyrolysis gas through an oxidization reaction and pyrolyse high molecular hydrocarbon in the pyrolysis gas with a heat generated by the oxidization reaction so as to obtain a cracked gas containing low molecular hydrocarbon.
a residue cooling step for cooling the pyrolysis residue generated in the pyrolysis step for solidification;
a mechanical processing step for crushing and sorting the pyrol
Kaneko Masaki
Yoshimori Masashi
Ferensic Denise L.
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Rinehart K. B
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