JP4350485B2 - Method and apparatus for firing and detoxifying multiple / mixed contaminants - Google Patents

Description

  The present invention is a treatment method for detoxifying incinerated ash and incinerated fly ash containing soil and organic chlorine compounds such as dioxins, PCBs, and harmful heavy metals, and further processing into materials for construction and civil engineering, And a processing system (processing device).

  In recent years, as social concerns about environmental issues have increased, laws related to recycling, waste, and soil contamination have been improved, and incineration ash generated from incineration facilities, incineration fly ash and contaminated soil in factory sites, There is a need for the development of technology that can detoxify hazardous substances in industrial waste and can be recycled as resources.

Detoxification technology for each pollution source and recycling technology for each detoxification product have already been developed alone.
However, there are many compounds that are contaminated by dioxins and contain toxic heavy metals, and incineration ash can be roughly divided into main ash and fly ash, but it contains contamination. There are various kinds of substances.

It is possible to detoxify pollutants using equivalent detoxification technology for complex pollutants, but each consumes energy and exclusive detoxification chemicals. Will increase.
In addition, handling costs such as transportation are increased, and there is a concern about secondary contamination during transportation.

  In the present invention, in view of the above-mentioned problems, incinerated ash, incinerated fly ash, contaminated soil, and a variety of contaminants can be detoxified at the same time without using special chemicals. The purpose is to process even raw materials.

  In addition, the purpose is to minimize the energy used for the processing related to detoxification and recycling, to reduce processing costs related to movement, etc., and to prevent secondary contamination.

In order to achieve the above object, the present invention comprises a step of granulating a plurality of types of pollutants such as incinerated main ash, incinerated fly ash, and soil, and firing the granulated pollutants in a low oxygen atmosphere. And a step of performing.
In addition, organic chlorine compounds such as dioxins and PCBs and harmful heavy metals contained in plural / complex contaminants can be rendered harmless at the same time.
In this case, the exhaust gas generated by burning the pollutants is mixed with combustion air, and the fuel is burned to make it in a low oxygen atmosphere, and the temperature in the firing furnace is maintained below the melting temperature of the fired product. To do.
Further, the present invention is characterized in that heavy metal is reduced at the time of firing by mixing wood waste fuel and / or RPF fuel with granulated pollutants, thereby reducing the fuel for firing.
The processing apparatus includes a pollutant granulating means, a firing furnace for firing the granulated contaminant, and a means for adjusting the inside of the firing furnace to a low oxygen atmosphere.
More specifically, incineration ash / incineration fly ash / contaminated soil is separated by particle size with a comb machine, granulated and used as raw material, and crushed wood waste fuel or RPF fuel or both are mixed into the raw material The process of charging the calcining kiln with a quantitative supply device, the process of rapidly reducing the exhaust gas temperature with a temperature reducer, collecting and discharging dust with a bag filter, and the combustion for adjusting the oxygen concentration in the calcining kiln It consists of an air introduction device.
The RPF fuel may be RDF or waste plastic.
The incinerated fly ash may be alkaline fly ash containing a large amount of slaked lime discharged from the bag filter.

According to the detoxification treatment of incineration ash, incineration fly ash, and contaminated soil, various pollutants can be made safe and harmless at the same time.
In addition, if a raw material storage pit for temporarily storing the granulated material is provided, it is possible to cope with changes in the amount of incoming goods, and it is possible to make harmless and recycle efficiently.

  Crushed wood scraps and RPF fuel are used to save energy of the burner heat source necessary for firing due to the fixed carbon contained in them, and the fixed carbon possessed has a reducing action on heavy metals in the firing kiln and is particularly harmful. Suppresses generation of valent chromium and promotes heavy metal volatilization.

When incinerated ash and incinerated fly ash having a constant particle size are mixed by granulation and a magnetic separator, and granulated, the particle size of the baked product is fixed and it is easy to recycle.
Further, it is known that alkaline fly ash containing slaked lime discharged from bag filters that are frequently used in recent incineration facilities is fixed when fired alone.
However, sticking can be prevented by performing mixed granulation.

The firing air supplied during firing mixes the outside air and the final exhaust gas, and adjusts the oxygen concentration and temperature in the firing kiln by adjusting the balance.
The amount of adjustment may be manual or manual using a feedback signal from an oxygen concentration measuring device added to the chimney.
It is a known fact that the combustion temperature increases when the oxygen concentration is lowered.
In order to volatilize heavy metals, low oxygen operation is preferable. Therefore, when the oxygen concentration is lowered, the temperature in the firing furnace rises too much, causing melting.
In the present invention, a method is used in which the temperature inside the furnace is not increased to the low oxygen melting temperature while the inside of the furnace is kept in a low oxygen state by introducing exhaust gas having a lower oxygen concentration than the outside air.
The low oxygen state generally means 7% by volume or less.

  The fuel for the combustion burner may be any of heavy oil, kerosene, and recycled oil.

  The fuel for the combustion burner is preferably regenerated oil when adjusting the running cost and the oxygen concentration in the kiln.

  In order to prevent scattering of processed products and products from the facility, it is preferable to fold the sealed structure so that external scattering does not occur as much as possible.

According to the present invention, wood scrap, RPF, RDF, or waste plastics crushed from incinerated ash, incinerated fly ash, soil, etc. contaminated with harmful organic chlorine compounds and heavy metals including dioxins, at a certain ratio By adding and baking, it can be rendered harmless at the same time.
In particular, it has the excellent effect of being able to treat pollution caused by toxic organochlorine compounds and heavy metals at the same time, and at the same time, it is possible to use solid fuel produced from waste as fuel and waste plastic as waste as thermal energy. It has the feature of being able to treat waste using waste.
In addition, the processed product has an excellent feature that it contributes to a recycling society in which it can be reused as various raw materials.

Hereinafter, a method for simultaneously detoxifying incineration ash, incineration fly ash, and contaminated soil according to an embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a diagram schematically showing an overall flow in the simultaneous detoxification method for incineration, incineration fly ash and contaminated soil according to the present embodiment.
FIGS. 2 and 3 show the test results of the examples of the products detoxified by the simultaneous detoxification method for incineration ash, incineration fly ash and contaminated soil in FIG.

  The simultaneous detoxification method for incineration ash, incineration fly ash, and contaminated soil in FIG. 1 is the vibration comb machine 3, magnetic separator 4, crusher 5, metal storage facility 6, granulator 7, and raw material storage pit 8 to be treated. , Loading cranes 9 and 10, raw material hopper 11, fixed quantity supply device 12, firing furnace 13, secondary combustion burner 14, combustion burner 15, cooling conveyor 16, heavy oil tank 18, combustion fan 19, drive motor 20, temperature reducer 21 , A low temperature water tank 21a, a fly ash collection and storage box 21b, a bag filter 22, a slaked lime supply feeder 22a, a fly ash collection and storage box 21b and 22b, a compressor 22c, a blower 23, a chimney 24, and an oxygen concentration meter 25.

    The process for treating contaminants in the method of simultaneous detoxification of incinerated ash, incinerated fly ash, and contaminated soil in FIG. 1 will be described with reference to FIG.

  Referring to FIG. 1, the pollutants to be treated are pollutants containing incinerated main ash, incinerated fly ash, dioxins such as soil, bottom sediment, pulverized material and sediment, and organic chlorine compounds such as PCB. The raw materials are stored in the storage locations 1 and 2.

Here, relatively large items such as incineration ash are put into the vibrating comb machine 3 from the raw material storage place 1 by the feeding crane 9.
Those having a particle size of 10 mm or more pass through the magnetic separator 4 by the belt conveyor and enter the crusher 5.
The crushed incineration ash is returned to the raw material storage place 1.
Note that the incineration ash in the raw material storage location 1 may be contaminated soil, sediment, crushed material, sediment, or the like.
Metals selected by the magnetic separator 4 are stored in the metal scrap storage facility 6, sent to a recycler, and recycled.

The sorted incineration ash is conveyed by a granulator 7 belt conveyor.
Combustion fly ash having a small particle size is conveyed directly from the raw material storage location 2 to the granulator 7 by the input crane 9.

The mixture is granulated by the granulator 7, processed into a granulated product of approximately 1 to 10 mm, and stored in the raw material storage pit 8.
The amount of scattering is very small because of appropriate humidification during granulation.

The granulated material stored in the raw material storage pit 8 is conveyed to the raw material hopper 11 by the input crane 10.
At that time, in order to reduce the heating fuel and reduce heavy metals, it is mixed with crushed wood waste fuel and RPF fuel.
If the raw material contains a large amount of fixed carbon, adjust the auxiliary fuel mixing ratio in a timely manner.

The calcined raw material charged into the raw material hopper 11 is charged by a fixed amount into a rotating cylindrical calcining furnace 13 by a fixed amount.
The fixed amount supply device 12 includes an upper shutter 12c and a lower shutter 12d and adopts a double door system, and separates the outside air and the inside of the baking furnace.
The fixed amount supply device is water-cooled (12e) around the supply port, and is supplied to the heating portion of the baking furnace 13 in a fixed amount by the input pusher 12b.

The rotating cylinder is rotationally controlled by the drive motor 20 (the transmission portion is not shown), and the rotating cylinder has an inclination angle of about 1 ° to 2 °. It moves inside for a certain time and is discharged.
A lifter or paddle blade for scrubbing contaminants may be mounted in the rotating cylinder.

The fuel of the combustion burner 15 may be any of heavy oil, kerosene, and recycled oil.
The flame generated from the burner is converted into high temperature hot air in the hot air generating furnace 15a, and acts as a firing heat source.
The hot air temperature needs to be 600 ° C or higher, but is preferably 800 ° C or higher.
Further, it is preferable to keep the inside of the firing furnace in a low oxygen state.
The low oxygen state means an oxygen concentration of 7% by volume or less.

In order to maintain a low oxygen state, it can be achieved by reducing the amount of air blown from the combustion air blower fan 19.
However, when the amount of blown air is reduced, the gas temperature from the hot air generating furnace rises, and when it exceeds 1200 ° C., most types of fired products are melted.
When the rotating cylindrical firing furnace melts, it impedes the conveyance of the fired product.

Therefore, exhaust gas is introduced from the chimney 24, and combustion air having a low oxygen concentration is supplied in an appropriate ratio to normal outside air, thereby maintaining a low oxygen state and preventing an increase in the gas temperature of the hot air generating furnace.
Automatic control is also possible by a feedback signal from the continuous oxygen concentration analyzer 25.

While the composite pollutant passes through the firing furnace 13, the organic chlorine compounds such as dioxins and PCB are thermally decomposed.
Heavy metals having a low vaporization temperature mainly cause volatilization of chloride and flow into the exhaust gas treatment device together with the exhaust gas separated from the pollutants.

The fired product from which the composite contaminants have been separated is discharged from the rotating cylinder at a product temperature of approximately 800 ° C. and is conveyed to the cooling conveyor 16.
During the conveyance of the cooling conveyor, the fired product is cooled to 100 ° C. or lower and is transported to the fired product storage place 17.
As described above, pollutants containing dioxins, organic chlorine compounds such as PCB, and heavy metals can be rendered harmless and the residue can be carried out to the outside.
In addition, since organic components are burned and separated as a synergistic effect, it is easy to use as a construction / civil engineering material.

  While the exhaust gas is controlled by the secondary combustion burner and the secondary combustion fan 14a in the secondary combustion chamber, it is heated to a high temperature, for example, about 800 ° C., so that the organic chlorine compound contained in the hot air is completely combusted. Disassembled.

The exhaust gas in which the organic chlorine compound has been completely decomposed is rapidly reduced in temperature by the temperature reducer 21 in order to prevent resynthesis.
The exhaust gas is reduced in temperature to approximately 200 ° C. or less by spraying the low temperature water flowing from the low temperature water tank 21a.

In order to neutralize the acid gas released from fuels such as heavy oil and regenerated oil, mainly heavy metals that have been volatilized and chlorinated are mixed with neutralizing chemicals by the slaked lime supply device 22a in order to neutralize acid gases released from fuels such as heavy oil and recycled oil. Collect dust with a dust collector.
Reference numeral 22c denotes a compressor.
Since the collected dust 22b contains a high concentration of heavy metal, it is used as a raw material for metal recovery by a smelting technique or a Yamamoto reduction technique.
Clean exhaust gas that has passed through the dust collector is discharged from the chimney 24 to the atmosphere using the blower 23.

  Next, as an embodiment according to the present invention, the simultaneous detoxification system of FIG. 1 is configured on a small scale (processing capacity 10 kg / hour), and harmless for a sample in which about 100 kg of heavy metal-containing incinerated main ash and 20 kg of incinerated fly ash are mixed The calcination treatment was carried out to obtain a fired product.

Fig. 2 shows the results of elution tests and content tests of raw ash and fired products obtained by detoxification treatment according to the present invention, Fig. 3 shows the results of dioxins analysis of raw ash, and Fig. 4 shows the baked products. The dioxin analysis result of (calcined ash after a process) is shown.
As can be seen from FIG. 2, the contaminated incineration ash / incineration fly ash has a toxic heavy metal concentration lowered to the soil environment standard or less by the detoxification treatment according to the present invention.
Moreover, when the table | surface of FIG. 3 and FIG. 4 is compared, dioxins are falling remarkably clearly.

1 shows a detoxification system for incineration ash and the like according to the present invention. The harmful | toxic heavy metal detoxification test result of the incineration main ash and incineration fly ash which concerns on this invention is shown. The results of analysis of dioxins in raw ash before incineration main ash, incineration fly ash, etc. are shown. The dioxin analysis result of the baking ash (baking goods) detoxified by the method concerning this invention is shown.

Explanation of symbols

1 Raw material storage place for incineration ash (including contaminated soil, sediment, crushed material, sediment, etc.)
2 Raw material storage place such as combustion fly ash 3 Vibrating comb machine 4 Magnetic separator 5 Crusher 6 Metal scrap storage facility 7 Granulator 8 Raw material storage pit 9, 10 Loading crane 11 Raw material hopper 12 Constant supply device 12a Hydraulic unit 12b Input pusher 12c Upper shutter 12d Lower shutter 12e Water cooling device 13 Firing furnace 14 Secondary combustion burner 14a Secondary combustion fan 15 Combustion burner 16 Cooling conveyor 17 Firing product (raw material for construction and civil engineering materials)
18 Heavy oil tank 19 Combustion fan 20 Drive motor 21 Temperature reducing device 21a Temperature-reducing water tank 21b Fly ash collection storage box 22 Bag filter 22a Slaked lime supply feeder 22b Fly ash collection storage box (dust)
22c Compressor 23 Blower 24 Chimney 25 Oxygen meter

Claims (1)

Granulates multiple types of pollutants such as incinerated main ash, incinerated fly ash and soil,
Mixing the granulated pollutant with wood chip fuel and / or RPF fuel,
Put the mixture into a kiln kiln,
The inside of the firing kiln furnace is separated from the outside air,
The gas generated from the inside of the firing kiln furnace is subjected to secondary combustion, and then the temperature is reduced to 200 ° C. or lower. A combustion burner that blows flame into the firing kiln furnace with air mixed with the reduced exhaust gas and outside air. A pollutant detoxifying method characterized in that, by supplying, the inside of the kiln furnace is maintained in a low oxygen state of not more than the melting temperature of the fired product and not more than 7% by volume .

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