JPH0985213A - Ash processing and facilities therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively thermally decompose dioxin contained in ash, and at the same time, prevent ash from being solidified by partial high temperatures, and also prevent a stirring device from becoming damaged by wear, by blowing an inert gas into the ash through the supply of the inert gas of a high temperature into a container, heating the ash in an oxygen-short state and maintaining this state for a specified time. SOLUTION: A fly ash stored in an ash storage container 15 is heated by the passage of a high-temperature inert gas ejected from an aeration part 19, and the temperature of the fly ash is uniformly increased through the concurrent stirring and fluidization of the fly ash. In addition, the dioxin contained in the fly ash is thermally decomposed by maintaining this state for a specified time or longer. Further, if the ash storage container 15 is vibrated by a vibration device 18, the fly ash is vibrated, so that a passage hole for inert gas is collapsed to realize an effective heating. The inert gas after heating is dehydrated by a condenser 24 following the removal of the fly ash by a dust filter 23, and then is introduced into a heat exchanger 26. Finally, the inert gas is again heated by an exhaust gas from a dust incinerator 11 to be recycled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention treats fly ash containing toxic substances such as dioxin collected from exhaust gas discharged from a refuse incinerator, and incineration distribution containing toxic substances such as dioxin. The present invention relates to a method and equipment for treating ash that is rendered harmless.

[0002]

2. Description of the Related Art Conventionally, in a refuse incineration facility, there is, for example, one shown in FIG. 3 as a facility for detoxifying fly ash collected from exhaust gas. This is provided with an ash storage tank 3 for storing fly ash, a dioxin thermal decomposition device 1, and a heavy metal stabilization device 2. The thermal decomposition of dioxin is carried out by heating at a predetermined temperature or higher in an oxygen-deficient state and holding it for a predetermined time. The heating temperature and the reaction time are determined by the oxygen concentration contained in the gas. For example, the amount of oxygen is 1.0 wt. %, The heating temperature may be kept at 300 ° C. or higher for 60 minutes or longer. The dioxin thermal decomposition apparatus 1 is provided with a reactor 1a that heats fly ash by stirring and kneading to thermally decompose dioxin, and a cooler 1b that cools the heat-treated fly ash while stirring. The heavy metal stabilizing device 2 is provided with a kneader 2a for stabilizing the heavy metals by adding a chelating agent to the fly ash after heat treatment and cooling, a carry-out conveyor device 2b, and a storage pit 2c.

[0003]

However, in the reactor 1a, the stirring casing is provided in the cylindrical casing, and the reactor 1a is heated up to the reaction temperature of 350 ° C. at which the dioxin is effectively thermally decomposed up to the center of the casing. To do so, the casing must be heated to 400-450 ° C. By the way, fly ash tends to solidify when heated to 400 ° C. or higher, and therefore, when a solidified layer of fly ash is formed on the inner surface of the casing, there is a problem that the stirring blade is worn or damaged.

An object of the present invention is to solve the above problems and to provide a method and equipment for treating ash which does not cause the problem of wear or damage of the stirring blade.

[0005]

In order to achieve the above object, the method for treating ash according to claim 1 of the present invention is a method in which a high temperature inert gas is supplied into a container in which the ash is charged to form a ash. It is characterized in that an inert gas is blown into the ash, the ash is heated in a state of insufficient oxygen, and the ash is held for a predetermined time to thermally decompose dioxin contained in the ash.

Further, the ash processing facility according to claim 5 is
In an ash treatment facility that detoxifies fly ash collected from the exhaust gas of a refuse incinerator, high-temperature inert gas is blown into the fly ash to heat it under the ash storage container that stores the fly ash collected from the exhaust gas. A gas inlet for discharging the inert gas is provided at the top of the ash storage container, and a dust collector is installed at this gas outlet, and the ash outlet formed at the bottom of the ash storage container is blown. It is characterized by being connected to an ash cooling device.

According to the above-mentioned ash treatment method, a high-temperature inert gas is blown into the ash to heat the ash uniformly so that the dioxin contained in the ash can be thermally decomposed effectively. Since a part of the ash is not heated and solidified, and there is no mechanical stirring element, no problem due to ash solidification occurs.

Further, according to the ash treatment facility, in addition to the effect of the above method, dioxin is thermally decomposed by utilizing a conventional ash storage container, so that the installation space can be greatly reduced.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Here, an embodiment of a fly ash treatment facility in a refuse incinerator according to the present invention will be described with reference to FIGS.

As shown in FIG. 1, an exhaust gas path 10 for discharging exhaust gas discharged from a refuse incinerator 11 through a chimney 12.
Include a temperature control tower 13 that cools the exhaust gas by spraying cooling water, chlorides and sulfides that are generated by reacting with the dust contained in the exhaust gas and the chemical agent blown into the exhaust gas,
A bag filter 14 for collecting fly ash containing heavy metals is provided.

Reference numeral 15 is an ash storage container which also serves as a reaction container.
The fly ash collected by the temperature control tower 13 and the bag filter 14 is discharged to the ash recovery pipe 16 by the ash carriers 13a and 14a, and the ash storage container 15 is passed through the inlet rotary valve 17.
Be delivered to. In this ash storage container 15, a funnel portion 15b having an inclination angle α (Fig. 2) set to 70 degrees or more from the repose angle of fly ash is formed in the lower portion of a cylindrical portion 15a, and these container walls are kept warm by a heat insulating material. It is configured as a wall, or as a heating wall provided with a heating gas passage for leading the exhaust gas out of the exhaust gas passage 10. Also, this ash storage container 1
5 is supported by an elastic member, and is provided with a vibrating device 18 for vibrating the fly ash inside.

Further, in the funnel portion 15b of the ash storage container 15,
An aeration section 19 for blowing an inert gas (for example, nitrogen gas or argon gas) at 400 to 500 ° C. for fluidization and heating into the fly ash is provided. As shown in FIG. 2, the aeration portion 19 has a gas injection port 19 formed in the wall of the funnel portion 15b at a regular interval in the circumferential direction.
a and a cover 19b that covers the outer periphery of the gas blowing port 19a,
The baffle plate 19c is attached to the upper part of the gas injection port 19a on the inner surface of the wall of the funnel portion 15b and prevents the inflow of fly ash. An ash extraction pipe 20 is connected to the bottom of the ash storage container 15 and an outlet rotary valve 20a is interposed.

A gas exhaust port 21 for exhausting an inert gas is formed at the top of the ash storage container 15 and a gas exhaust pipe 22 is connected to the ash storage container 15. A dust filter is provided between the gas exhaust port 21 and the gas exhaust pipe 22. 23 is attached. The gas discharge pipe 21 is connected to a condenser 24 that separates water vapor from the inert gas. In the middle of the gas circulation pipes 25A and 25B connected to the discharge side of the condenser 24, for heating gas, the inert gas is heated to 400 to 500 ° C. by the exhaust gas introduced from the exhaust gas passage 13 through the exhaust gas introduction pipe 10a. The heat exchanger 26 is interposed, and the gas circulation pipe 25B
The outlet is connected to the circulation fan 27. Reference numeral 29 is a gas supply pipe for supplying a new inert gas to the gas circulation pipe 25B. Then, the inert gas is introduced into the aeration unit 19 via the gas supply pipe 28 by the circulation fan 27.

The outlet rotary valve 20a is connected via a fly ash conduit 31 to a kneader 32 having a cooling function and a heavy metal stabilizing function, which is an example of a fly ash cooler. That is, in the kneading machine 32, the fly ash after the treatment is stirred by the kneading screw 32 a inside and is cooled by the humidifying water supplied from the cooling water supply pipe 33, and the chemical supply pipe 3 is further supplied.
The heavy metal contained in the fly ash is stabilized by the chelating agent (heavy metal stabilizer) supplied from No. 4, and is discharged to the pit 35. The steam generated in the kneader 32 is sent to the dust filter 23 through the steam discharge pipe 36 and separated by the condenser 24.

In the above structure, the fly ash stored in the ash storage container 15 is heated by passing the high temperature inert gas ejected from the aeration section 19, and the kinetic energy of the inert gas is large. In this case, the fly ash is heated while being stirred and fluidized, and the temperature is uniformly raised. By maintaining this state for a certain time or longer, dioxin contained in the fly ash is effectively thermally decomposed. Further, when the ash storage container 15 is vibrated by the vibrating device 18, the fly ash is vibrated and the passage hole for the inert gas is collapsed,
The blown-in inert gas is prevented from being blown out, and the gas is effectively heated. After the fly ash is removed by the dust filter 23, the heated inert gas is further moisture-removed by the condenser 24 and then introduced into the heat exchanger 26, and 400 to 500 is supplied by the exhaust gas from the refuse incinerator 11. It is reheated to ℃ and recycled. Further, new inert gas is replenished from the gas replenishment pipe 29 as needed. Further, the treated fly ash is sent to the kneading machine 32 to be cooled, and a chelating agent is added to stabilize the heavy metal.

According to the above embodiment, Since the ash storage container 15 that has been conventionally used and stores fly ash is used as the reaction container, the occupied space can be significantly reduced and the size can be reduced. 2. Since the reaction container and the agitating screw device are unnecessary, the equipment cost can be reduced. 3. Since the heat of the exhaust gas discharged from the refuse incinerator 11 is used as the heating source of the inert gas, the operating cost can be reduced. 4. Usually, the fly ash storage container is configured to store the fly ash amount for 3 days, and by applying it to the ash storage container 15, the fly ash is stored in the ash storage container 15 for a long time. To be done. Therefore, since the heat treatment can be performed in the ash storage container 15 for a sufficient time, the decomposition rate of dioxin can be extremely increased. 5. Since the high temperature inert gas is passed or fluidized to heat the fly ash, the fly ash can be uniformly heated, the temperature of the fly ash is not partially increased, and no problem occurs due to solidification of the fly ash. 6. By vibrating the ash storage container 15 by the vibrating device 18, the fly ash can be appropriately collapsed to prevent blow-through of the inert gas, and the fly ash can be reliably fluidized.

[0017]

As described above, according to the ash processing method of the present invention, the inert gas blown into the ash causes
Since the ash is passed through and heated, the ash can be uniformly heated, and the dioxin contained in the ash can be effectively thermally decomposed. As a result, a part of the ash is not heated and solidified, and since there is no mechanical stirring element, there is no inconvenience due to the solidification of the ash.

Further, according to the ash processing facility, in addition to the effect of the above method, since dioxin is thermally decomposed by utilizing the conventional ash storage container, the installation space can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a fly ash treatment facility in a refuse incinerator according to the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing an aeration section in an ash storage tank of the fly ash processing facility.

FIG. 3 is a configuration diagram showing an embodiment of a conventional fly ash processing facility.

[Explanation of symbols]

 10 Exhaust gas path 11 Waste incinerator 13 Temperature control tower 14 Bag filter 15 Ash storage container 15c Ash extraction port 18 Vibration device 19 Aeration section 19a Gas inlet 22A, 22B Gas circulation pipe 23 Dust filter 24 Condenser 26 Heat exchanger 32 Kneading Machine 33 Cooling water supply pipe 34 Chemical supply pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michio Ishida 5-3-8 Nishi-Kujo, Konohana-ku, Osaka City, Osaka Prefecture Hitachi Shipbuilding Co., Ltd.

Claims (8)

[Claims] 1. A dioxin contained in ash by supplying a high temperature inert gas into a container charged with ash and blowing the inert gas into the ash, heating the ash in a state of oxygen deficiency and holding it for a predetermined time. A method for treating ash, characterized in that the ash is decomposed. 2. The method for treating ash according to claim 1, wherein the container is vibrated to prevent the inert gas from blowing through. 3. The method for treating ash according to claim 1, wherein the ash is fluidized and agitated by the energy of the inert gas. 4. The ash according to claim 1, wherein when the fly ash collected from the exhaust gas of the refuse incinerator is treated, the heat of the exhaust gas heats the inert gas. Processing method. 5. In a ash treatment facility for detoxifying fly ash collected from the exhaust gas of a refuse incinerator, a high-temperature inert gas is blown to the lower part of the ash storage container for storing the fly ash collected from the exhaust gas. A gas inlet for blowing and heating into ash was provided, a gas outlet for discharging inert gas was provided at the top of the ash storage container, a dust collector was provided at this gas outlet, and it was formed at the bottom of the ash storage container. Ash treatment equipment characterized in that the ash outlet is connected to a fly ash cooling device. 6. The ash processing facility according to claim 5, wherein the ash storage container is provided with a vibrating device for vibrating the fly ash to prevent blow-through of the inert gas. 7. The fly ash cooling device is provided with a heavy metal stabilizing function for stabilizing heavy metals contained in the fly ash by adding a heavy metal stabilizer to the fly ash and stirring and kneading the fly ash. Item 5. The ash processing facility according to item 5 or 6. 8. The ash treatment according to claim 5, further comprising a gas heating heat exchanger for heating the inert gas by the heat of the exhaust gas discharged from the refuse incinerator. Facility.