JP3222070B2 - Ash detoxification equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fly ash which is entrained in exhaust gas discharged from, for example, a waste incinerator and collected by a bag filter or the like, contains dioxin, and is thermally decomposed. The present invention relates to a detoxifying apparatus for detoxifying ash.

[0002]

2. Description of the Related Art Dioxin (hereinafter referred to as DX) is a harmful substance.
It is known that ash can be thermally decomposed by heating the ash to 400 ° C. or higher in an oxygen-free state for a predetermined time. Conventionally, in a refuse incineration plant, a ash detoxifying apparatus has been used for a certain period of time at a predetermined temperature (for example, 400 ° C.) while stirring fly ash collected from exhaust gas in an inert gas atmosphere (oxygen-free atmosphere) using nitrogen gas. Some reactors include a reactor 1 for thermally decomposing DXN by holding the same, and a cooler 2 for further cooling the thermally decomposed ash in an inert gas atmosphere.

[0003]

However, since such a device handles extremely toxic DXN, a double safety measure for preventing leakage without being pyrolyzed is desired.

An object of the present invention is to solve the above problems and to provide a safer ash detoxification apparatus.

[0005]

According to the first aspect of the present invention, in order to achieve the above object, the ash is heated to a predetermined temperature in an inert gas atmosphere and held for a predetermined time to thermally decompose dioxin. A heater, a cooler for continuously cooling the ash treated by the heater in an inert gas atmosphere, and an ash inlet from an ash outlet side of the heater via an ash supply pipe, In a ash detoxification apparatus including a condenser for removing moisture in a gas and a vent gas pipe having a gas discharge pipe for adjusting a gas pressure in a heater, an inert gas is provided in a vent gas pipe from the heater to the condenser. A gas heating device for heating dioxin in a gas to a temperature at which it can be decomposed is provided.

According to the above configuration, the gas heating device provides
Since the inert gas extracted from the heater is heated at the inlet, even if dioxin is accompanied by the inert gas, dioxin can be thermally decomposed reliably.
Safety can be further improved. Further, the treatment of the water separated by the condenser can be performed safely only by preventing the dissolution of heavy metals such as mercury by the chemical treatment device. Further, when vent gas is discharged for pressure adjustment, it becomes possible to release an inert gas into the atmosphere. Therefore, there is no need for a conventional pipe for returning refuse to the incinerator.

In the above structure, a detour path is formed in the vent gas pipe in which the gas heating device is disposed, by a detour member for extending a flow distance of the inert gas.

[0008] According to the above configuration, by extending the passage to be heated, the heating time of the inert gas can be extended, and the thermal decomposition of dioxin can be performed more reliably.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ash detoxification apparatus according to the present invention will be described with reference to FIGS.

As shown in FIG. 1, a reactor 11, which is a heater, includes a stirring paddle 11c, which is rotatable around an axis and rotationally driven by a stirring motor 11b, inside a cylindrical casing 11a. A heater (not shown) is provided on the outer periphery of 11a. An ash hopper 12 is connected to an ash inlet 11 d formed on the upstream side of the reactor 11 via an ash supply pipe 13, and a rotary valve 14 is interposed in the ash supply pipe 13. A transfer pipe 16 connected to an ash cooler 15 serving as a cooler is attached to an ash outlet 11 e formed on the downstream side of the reactor 11. Above the ash outlet 11e, a vent gas pipe 17 for circulating an inert gas, for example, nitrogen gas in the reactor 11, is connected via a dust filter 18, and the tip of the vent gas pipe 17 is connected to a rotary valve 1
It is connected to an ash supply pipe 13 between the casing 4 and the casing 11a.

The ash cooler 15 has a stirring paddle 15c which is rotatable around an axis and is rotationally driven by a stirring motor 15b inside a cylindrical casing 15a, and a cooling water pipe ( (Not shown)
Is provided.

The vent gas pipe 17 is provided with a gas heating device 21 according to the present invention, a condenser 22 for sucking nitrogen gas from a heater to remove moisture in the nitrogen gas, and a nitrogen gas. A circulation fan 23 for circulating, a gas discharge pipe 25 provided with a pressure regulating valve 24 for maintaining a constant nitrogen gas pressure in the reactor 11, and a gas cylinder 26
And a gas supply pipe 27 for supplying nitrogen gas as necessary.

Normally, in the reactor 11, DXN in ash is 9
Since it is thermally decomposed by 5 to 99% or more, DXN discharged together with the nitrogen gas from the outlet side is considered to be extremely close to 0. However, considering the case where DXN is discharged due to some accident or a change in operation state, the A heating device 21 is provided. This gas heater 21 is, as shown in FIGS.
The nitrogen gas discharged from the dust filter 18 is converted to DXN
Heater (heating means) 31 for heating the gas to 400 ° C. or higher, which is a temperature at which the gas can be decomposed, and a large number of baffles (circumvention members) which form the flow path of the vent gas pipe 17 in a detour shape to secure the heating time ) 32. The baffle plate 32 is formed in an arc shape, and is attached to the inner surface of the vent gas pipe 17 at a predetermined interval in a relative direction.
3 are formed.

A drain tank 28 for temporarily storing the water discharged from the condenser 22 is disposed, and the drainage tank 28 is connected to the chemical treatment device 3 via a water pipe 29.
0 and is configured to prevent heavy metals such as mercury contained in water from being taken out.

In the above configuration, fly ash collected by a temperature control tower, a bag filter, or the like provided in an exhaust gas path of a refuse incinerator enters the reactor 11 in a nitrogen gas atmosphere from the ash hopper 12 through the ash inlet 11d. When supplied, the DXN in the ash is thermally decomposed by being heated by the heater while being stirred by the stirring paddle 11c and maintained at about 400 ° C. for a predetermined time. Then, it is sent from the transfer pipe 6 to the ash cooler 15, stirred and cooled in nitrogen gas, and discharged from the ash extraction pipe 19.

On the other hand, the nitrogen gas in the reactor 11 is circulated by the circulation fan 23 through the vent gas pipe 17. After dust is removed from the ash outlet 11 e side of the reactor 11 by the dust filter 18, the dust is heated to 400 ° C. or more by the gas heating device 21 in the vent gas pipe 17 between the dust filter 18 and the condenser 22. The nitrogen gas is maintained at a high temperature for a predetermined time while being sent through the bypass path 33 formed by the baffle plate 32, and is reliably thermally decomposed even if DXN is entrained. This DXN is heated at about 400 ° C. in an oxygen-free atmosphere and is thermally decomposed if held for a predetermined time. However, if the ash exceeds 400 ° C., solidification may decrease. However, in the case of this nitrogen gas,
Further heating is possible, and the higher the temperature, the shorter the holding time may be. For example, when heated to 800 ° C., DXN can be decomposed in about 2 seconds.

Further, in the vent gas pipe 17, the pressure adjusting valve 24 and the gas supply valve 27a are adjusted by a measuring instrument such as a pressure gauge (not shown) so that the nitrogen gas pressure in the reactor 11 is maintained within a predetermined range. Conventionally, the gas discharge pipe 25 for discharging the nitrogen gas is configured to be introduced into a refuse incinerator in consideration of safety. In the case of this embodiment, however, DXN is mixed into the vent gas pipe 17. And no heavy metals (especially mercury vapor) are removed by the condenser, so that nitrogen gas can be released to the atmosphere, and the piping connecting the gas discharge pipe 25 to the refuse incinerator is eliminated. Can be.

Further, from the condenser 22 to the drain tank 2
The water discharged to 8 does not contain any DXN, and heavy metals such as mercury contained in the water can be used for landfill without causing environmental pollution due to chemicals (such as chelating materials) supplied in the chemical treatment device 30. It is processed.

According to the above embodiment, the heater 31 of the gas heating device 21 is provided near the inlet of the vent gas pipe 17 for circulating nitrogen gas.
Even if N is entrained, thermal decomposition can be reliably performed, and nitrogen gas containing no DXN can be circulated. Moreover, since the bypass path 33 is formed in the vent gas pipe 17 by a large number of baffles 32, the residence time of the nitrogen gas heated by the gas heating device 21 can be sufficiently long, and the DXN can be thermally decomposed reliably. it can. Thus, the nitrogen gas discharged from the vent gas pipe 17 can be discharged into the atmosphere from the gas discharge pipe 25, and the piping conventionally connected to the waste incinerator can be eliminated. In addition, DX separated into water separated from condenser 22
Since N is not included, the medicine processing device 30
Thereby, wastewater treatment can be performed safely.

[0020]

As described above, according to the first aspect of the present invention, since the inert gas extracted from the heater is heated at the inlet by the gas heating device, dioxin is added to the inert gas. May be accompanied,
Dioxin can be reliably pyrolyzed, and safety can be further improved. Further, the treatment of the water separated by the condenser can be performed safely only by preventing the dissolution of heavy metals such as mercury by the chemical treatment device. When discharging vent gas for pressure adjustment,
Inert gas can be released into the atmosphere. Therefore, there is no need for a conventional pipe for returning to the incinerator.

According to the second aspect of the present invention, the heating time can be extended by extending the passage to be heated, and the thermal decomposition of dioxin can be performed more reliably.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an ash detoxification processing apparatus according to the present invention.

FIG. 2 is a longitudinal sectional view showing the gas heating device.

FIG. 3 is a sectional view taken along the line AA shown in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Reactor (heater) 12 Ash hopper 15 Ash cooler (cooler) 17 Vent gas pipe 18 Dust filter 21 Gas heating device 22 Condenser 23 Circulation fan 24 Pressure control valve 25 Gas exhaust pipe 26 Gas cylinder 27 Gas supply pipe 28 Tren tank 29 Drain Tube 30 Chemical treatment device 31 Heater 32 Baffle (bypass member) 33 Bypass route

Claims (2)

(57) [Claims] 1. A heater that heats ash to a predetermined temperature in an inert gas atmosphere and holds the ash for a predetermined time to thermally decompose dioxin; and continuously heats the ash treated by the heater in an inert gas atmosphere. A cooler for cooling, from the ash outlet side of the heater
In a ash detoxification apparatus, which is connected to an ash inlet via an ash supply pipe and includes a condenser for removing water in an inert gas and a vent gas pipe having a gas discharge pipe for adjusting gas pressure in a heater. An ash detoxification apparatus, wherein a gas heating device for heating dioxin in an inert gas to a decomposable temperature is provided in a vent gas pipe from the heater to the condenser. 2. A detour path is formed by a detour member in a vent gas pipe in which said gas heating device is disposed to extend a flow distance of an inert gas.
The ash detoxifying apparatus according to the above.