JP2752333B2 - Waste incineration method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to sewage sludge, municipal waste,
The present invention relates to a waste incineration method and apparatus for incinerating waste such as industrial waste by a fluidized bed incinerator.

[0002]

2. Description of the Related Art A conventional general fluidized bed incinerator has a fluidized bed formed of silica sand having a particle size of about 0.3 to 0.9 mm as a fluidized medium, and the fluidized medium is maintained at 650 to 800.degree. Waste is charged in this state, and combustion is performed by the heat capacity of the fluid medium and the stirring action.

[0003] However, incineration ash discharged from such a fluidized bed incinerator is liable to generate dust because it is fine particles.
Further, since the bulk density is very small, 0.4 to 0.7 t / m ³ , handling is not easy, and there is a problem that the cost of landfill is increased. In addition, the flow rate in the furnace must be suppressed to about 1.2 m / s or less in order to prevent the fluid medium from being blown off, and there is a problem that the throughput per unit area of the furnace cannot be increased.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and eliminates the generation of incinerated ash which is expensive to dispose of. An object of the present invention is to provide a waste incineration method and apparatus capable of obtaining ash and increasing the throughput per unit area of a furnace.

[0005]

Means for Solving the Problems A waste incineration method according to the present invention, which has been made to solve the above problems, granulates incinerated ash recovered from exhaust gas of a fluidized bed incinerator for incinerating waste. This is thrown into a fluidized bed sintering furnace having a higher temperature than the fluidized bed incinerator installed in the return pipe for returning the blown-off fluid medium collected by the dust collecting device to the fluidized bed incinerator, and sintering. It is characterized by the following.

[0006] Further, a waste incinerator according to the present invention, which has been made to solve the above-mentioned problems, comprises a fluidized bed incinerator for incinerating waste, a primary dust collector for collecting a blow-off fluid medium, and
A secondary dust collector for collecting incinerated ash from exhaust gas, a granulator for granulating the collected incinerated ash, and a fluidized bed sintering sintering at a higher temperature than the fluidized bed incinerator while flowing the granulated ash. Kiln and
The blow-off fluid medium collected by the primary dust collector is returned to the fluidized bed sintering furnace, and the fluidized medium in the fluidized bed sintering furnace and the exhaust gas of the fluidized bed sintering furnace which have become high temperature are returned to the fluidized bed incinerator. And a return pipe.

[0007]

According to the present invention, incineration ash recovered from the exhaust gas of a fluidized bed incinerator is granulated and sintered in a fluidized bed sintering furnace having a higher temperature than the fluidized bed incinerator. As a result, it is possible to obtain a high-strength granulated sintered ash without the generation of incinerated ash in the form of fine particles as described above. Further, the flow rate in the furnace can be significantly increased from 4 to 8 m / s as compared with the conventional method, so that the amount of waste disposal per unit area of the furnace can be increased.

Further, according to the present invention, the fluidized bed incinerator is maintained at 700 to 900 ° C suitable for incineration of waste, and the fluidized bed sintering furnace is maintained at 900 to 1050 ° C suitable for sintering granulated ash. Therefore, there is an advantage that the overall heat energy loss is smaller than when incineration and sintering are performed in the same furnace.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the illustrated embodiments. Reference numeral 1 denotes a fluidized bed incinerator, and waste such as sewage sludge is introduced into the furnace through a waste inlet 2 and contacts with a fluidized medium 3 forming a fluidized bed by fluidized air.
Incinerated at 700-900 ° C. In the present invention, the fluidized bed incinerator 1
The flow rate inside the furnace is significantly higher than that of the conventional fluidized bed incinerator.
Since the flow rate is set to 8 m / s, the fluid medium 3 is blown off from the furnace top together with the exhaust gas and discharged to the outside of the furnace. Is sent to a fluidized bed sintering furnace 16 by a return pipe 15. Exhaust gas containing fine incineration ash passes through the first heat exchanger 4 and the second heat exchanger 5 while the blower 6
After being cooled by performing heat exchange with air supplied from 7, the air is guided to a secondary dust collecting device 8 such as a bag filter.

The incinerated ash of fine particles contained in the exhaust gas is collected by the secondary dust collector 8. The collected incinerated ash is made into granulated ash having a particle size of about 1 to 8 mm by a granulator 9, further dried by a dryer 10 receiving heat from the second heat exchanger 5, and Supplied to 16.

The fluidized bed sintering furnace 16 is a fluidized bed furnace maintained at a temperature of 900 to 1050 ° C., which is higher than that of the fluidized bed incinerator 1.
The granulated ash is sintered at a high temperature to obtain a granulated ash having high strength.
The high temperature fluid medium in the fluidized bed sintering furnace 16 is passed through a return pipe 17 extending from the upper part of the fluidized bed sintering furnace 16 to obtain the fluidized bed incinerator 1.
To the fluidized medium of the fluidized bed incinerator 1 again. For this reason, there is no need to reduce the flow velocity in the furnace in consideration of the blow-off of the fluid medium, and it is about 5 to 4 times the conventional value of 4 to 8 m / m.
s, and the amount of waste disposal per unit area of the furnace can be greatly improved.

The granulated sintered ash is taken out from a valve 18 provided at the lower end of the fluidized bed sintering furnace 16 and can be used as high strength aggregate. Numeral 12 is a valve provided at an incombustible discharge port 13 at the lower end of the fluidized bed incinerator 1, and the valve 12 can be opened to discharge incombustibles. The unburned matter discharged from the unburned matter discharge port 13 is put into a fluidized bed sintering furnace 16 and completely burned at a high temperature.

As described above, according to the present invention, incinerated ash in the form of fine particles is collected, granulated, and sintered in a fluidized bed sintering furnace 16 at a higher temperature than the fluidized bed incinerator 1. However, it is conceivable that this sintering is performed simultaneously in the fluidized bed incinerator 1. However, if such a method is adopted, the temperature inside the fluidized bed incinerator 1 must be raised to a temperature suitable for sintering the granulated ash, and the heat energy loss increases as a whole system. Will be done. In particular, in the case of sewage sludge containing a large amount of water, the loss is large, and the present inventor estimates that the method of the present invention can reduce the energy consumption by about 5 to 15% compared to this case. .

Next, the results of incineration of sewage sludge by the method and apparatus of the embodiment will be described. The used sewage sludge was obtained by dehydrating polymer-injected sludge to a water content of 78% with a dehydrator, and the physical properties are shown in Table 1.

[0015]

[Table 1]

In this embodiment, the incinerated ash recovered from the exhaust gas was granulated by a granulator 9 to a particle size of about 3 to 5 mm.
Since the granulated ash contains about 25% of water immediately after granulation, if it is put into the fluidized bed sintering furnace 16 as it is, the particles are destroyed by rapid water evaporation and the recovery rate is reduced. Therefore, in the present embodiment, the hot air heated to 150 ° C. by the second heat exchanger 5 was used, dried by the dryer 10 until the water content became 3% or less, and then put into the fluidized bed sintering furnace 16.

The fluidized bed incinerator 1 used is a small furnace having an inner diameter of 0.3 m and a height of 10 m, and the fluidized bed sintering furnace 16 has an inner diameter of 0.5 m.
m, height 2.5 m. The sludge incineration rate was about 120 kg / hr, and the air ratio was about 1.3. Set the temperature of fluidized bed incinerator 1 to 60
The temperature of the fluidized bed sintering furnace 16 was changed to 800, 900, 1000, 1050, and 1150 ° C. LNG (13A) was used as an auxiliary fuel, and silica sand (JIS No. 6) was used as a fluid medium. Table 2 shows the results and evaluation.
Shown in

[0018]

[Table 2]

The evaluation criteria in Table 2 are as follows. The sludge combustion state is 200 ppm or less of CO concentration in exhaust gas,
◎: If the ignition loss of the incinerated ash collected by the secondary dust collector is 1% or less, ◎, CO: 200 to 300 ppm, or 1 to 1.5% of the incinerated ash: ○, CO concentration 30
A case of 0 ppm or more or a loss on ignition of incinerated ash of 1.5% or more was evaluated as x. The uniaxial crushing strength was evaluated as ◎ for 5 kgf / particle or more, ○ for 3 to 5 kgf / particle, and × for 3 kgf / particle or less. Regarding the particle residual ratio, ◎ indicates 80% or more, ○ indicates 70 to 80%, and X indicates 70% or less. The overall evaluation was evaluated as ◎ when all of 〜 were 、, ○ when there was no X and no に お い て in ○, and × when there was even one X in 〜.

[0020]

As described above, according to the waste incineration method and apparatus of the present invention, it is possible to eliminate the generation of particulate incineration ash which is expensive to dispose of, and to provide a high strength material which can be used as an aggregate. Grain sintered ash can be obtained. The flow velocity in the furnace was 4
Since it can be increased to about 8 m / s, which is much larger than that of the conventional fluidized bed incinerator, the throughput per unit area of the furnace can be increased. Further, according to the present invention, it is possible to obtain high-strength granulated sintered ash that can effectively use incinerated ash as aggregate while preventing energy loss of the entire system.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 fluidized bed incinerator, 2 waste inlets, 3 fluidized media,
4 First heat exchanger, 5 Second heat exchanger, 6 Blower, 7
Blower, 8 secondary dust collector, 9 granulator, 10 dryer, 12
Valve, 13 Noncombustible material outlet, 14 Primary dust collector, 15
Return pipe, 16 fluidized bed sintering furnace, 17 Return pipe, 18 valve

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F23G 5/30 B09B 3/00 C02F 11/00

Claims (2)

(57) [Claims] 1. A return pipe for granulating incinerated ash collected from exhaust gas of a fluidized bed incinerator for incinerating waste and returning the blown fluid medium collected by a dust collector to the fluidized bed incinerator. A waste fluid incineration method, wherein the waste is put into a fluidized bed sintering furnace at a temperature higher than that of the fluidized bed incinerator installed in the middle of the step and sintered. 2. A fluidized bed incinerator for incinerating waste, a primary dust collector for collecting a blown-away fluid medium, a secondary dust collector for collecting incinerated ash from exhaust gas, and granulating the collected incinerated ash. Bed sintering furnace, a fluidized bed sintering furnace that sinters the granulated ash at a higher temperature than the fluidized bed incinerator, and a blow-off fluid medium collected by the primary dust collector into the fluidized bed sintering furnace. A waste incineration apparatus, comprising: a return pipe for returning a fluidized medium in a fluidized bed sintering furnace and a fluidized bed sintering furnace exhaust gas to the fluidized bed incinerator.