JPH10246418A - Facility for melting incineration residue of waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce equipment cost sharply and to maintain a high rate of operation by a system wherein molten slag collected in the furnace bottom part of a melting furnace of fly ashes and mixed ashes which melts incineration fly ashes by support gas containing oxygen of a specified value or above is made to flow down and solidified and granulated. SOLUTION: Incineration fly ashes are supplied to an oxygen burner 21 by dry air sent with pressure from a compressor 29. The oxygen burner 21 forms a high- temperature flame downward by support gas containing oxygen of 90% or more and the incineration fly ashes are supplied directly into the flame to be melted. Molten slag 30 of the ashes is collected in a furnace bottom part. Both of the molten slag 30 produced in a fly ash melting furnace 3 and molten slag produced in a mixed ash melting furnace are discharged from side walls thereof, pass through flow passages and flow down into a water tank of water granulation and solidification equipment. By melting mixed ashes comprising incineration ashes and the incineration fly ashes mixed in an appropriate ratio, by the mixed ash melting furnace, and by melting surplus incineration ashes by the fly ash melting furnace 3, the incineration fly ashes can be reduced in volume and stabilized without storing them normally almost at all.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incineration ash remaining in an incinerator by incineration of municipal waste, industrial waste, etc. by an incinerator, and an exhaust gas treatment system such as a bag filter which is discharged along with its exhaust gas. The present invention relates to a waste incineration residue melting facility for melting and processing incinerated fly ash trapped in a facility.

[0002]

2. Description of the Related Art When waste such as municipal waste and sewage sludge is incinerated, the incinerated ash is discharged from the bottom of the incinerator, and the fly ash is captured by a bag filter of an exhaust gas treatment system. The incinerated ash and incinerated fly ash thus generated are melted in a melting furnace such as an arc furnace or a resistance furnace in order to reduce and stabilize the volume, and then the molten slag is dropped into a water tank and solidified by rapid cooling. Crushed.

[0003]

[Table 1]

[0004] Table 1 exemplifies the amount and properties of incinerated ash generated when 1 ton of municipal solid waste is incinerated in a stoker type waste incinerator, and the incinerated fly ash captured by the exhaust gas treatment system. During exhaust gas discharged from Naogomi incinerators, and acid gases (HCl, SO _x, etc.) because it does, adding slaked lime to the reaction column is provided in an exhaust gas treatment system to neutralize it . Therefore, in this exhaust gas treatment system, a considerable amount of incinerated fly ash including this slaked lime is generated, and the specific volume of the incinerated fly ash is larger than that of the incinerated ash. In addition, incinerated fly ash has high scattering properties and easily absorbs moisture, causing solidification and deliquescence. Therefore, it must be stored in a closed state so as not to absorb moisture. Fly ash collected by the dust collector contains heavy metals such as lead and harmful substances such as dioxin, so it is designated as specially controlled waste and cannot be landfilled without treatment. In particular, since it is necessary to thermally decompose an organic chlorine compound such as dioxin in the melting process, storage is essential during periodic repair of the melting furnace. For this reason, conventionally, a large and airtight storage tank was required for storing the incinerated fly ash, and the equipment cost was extremely large.

[0005]

[Table 2]

Further, C _a O, as incineration ash are shown in Table 2
Since the ratio of the relative SiO ₂ is low basicity (C _a O / S
While iO ₂ ) is low, incineration fly ash has a significantly higher basicity than incinerated ash due to the addition of slaked lime. For this reason, if the incineration ash generated in the refuse incinerator and the incineration fly ash are mixed at the same generation ratio, the basicity becomes as high as 1.03 as exemplified in Table 2, and therefore, the arc melting furnace It is unavoidable that the refractory of the above will be significantly worn away in a short period of time and shorten its life. Further, as disclosed in Japanese Patent Application Laid-Open No. Hei 8-257533, which was filed and filed by the present applicant, the amount of incinerated fly ash generated is, for example, about 3
When one-half is mixed with incineration ash, its basicity is 0.1.
Since it can be suppressed to about 65, the erosion rate of the refractory becomes slow and the life can be prolonged. However, it was difficult to melt the entire amount of incineration fly ash in an arc melting furnace,
The need for the storage tank was still there.

[0007] For example, in the case of an arc type melting furnace, it takes one to two months to repair the refractory in a portion such as a hearth of the furnace which comes into contact with the molten slag. If it is to be stored, a huge storage tank will be required for that. In addition, two arc-type melting furnaces are installed,
It is conceivable to perform repairs alternately, but this is not preferable because it requires more space and equipment costs.

On the other hand, in Japanese Patent Application Laid-Open No. 8-313938, which was filed and filed by the applicant of the present invention, an oxygen burner using oxygen as a combustion gas is provided downward at the upper part of the furnace, and the high-temperature The flame is blown downward, and the incinerated fly ash is gas-conveyed and melted in the high-temperature flame, and the molten slag is discharged from the outlet at the lower part of the furnace side wall, while the exhaust gas is discharged from the exhaust port at the upper part of the furnace side wall. An ash melting furnace is disclosed, which makes it easier to treat incinerated fly ash.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention comprises a mixed ash melting furnace for melting a mixed ash of incinerated ash and incinerated fly ash, and a fly ash melting furnace. An object of the present invention is to provide a facility for melting waste incineration residues that can maintain an operation rate.

[0010]

For this purpose, the waste incineration residue melting facility of the present invention mixes incineration ash extracted from an incinerator and incineration fly ash extracted from an exhaust gas treatment system of the incinerator at an appropriate ratio. The incineration fly ash taken out of the exhaust gas treatment system of the incinerator and the mixed ash melting furnace that melts the ash is supplied to the oxygen burner by gas transfer, and a high-temperature flame is supplied from the oxygen burner into the furnace by a supporting gas of 90% or more oxygen. A compact fly ash melting furnace that blows downward and melts the incinerated fly ash; It is characterized by consisting of. Further, the present invention is characterized in that the portion of the mixed ash melting furnace which is in contact with the molten slag is formed of a refractory containing silicon carbide as a main component. Further, the present invention is characterized in that the exhaust gas of the mixed ash melting furnace and the exhaust gas of the fly ash melting furnace are each independently cooled, and then both exhaust gases are combined and discharged through a common exhaust gas treatment system. . In addition,
In the present invention, if the incineration fly ash has a relatively low basicity and if all the incineration ash can be treated in a mixing and melting furnace at a normal generation rate, only the incineration fly ash is fly ash during the periodic repair work of the mixing and melting furnace. It can also be applied to the case of processing in a melting furnace.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the overall flow of a waste incineration facility capable of processing 600 tons of general combustible waste per day.
In this facility, the exhaust gas discharged from the incinerator passes through a boiler to make effective use of the waste heat,
Exhaust gas is purified by passing through an exhaust gas treatment system including a bag filter dust collector, a denitration device, and the like, and is discharged into the atmosphere from a chimney. In this reactor, slaked lime is consumed as a neutralizing agent at 9 tons per day. Then, 42 tons / day of incinerated ash is taken out of the incinerator and the boiler, and 18 tons / day of incinerated fly ash is taken out of the reaction tower and the dust collector.

This is carried into the mixing / conveying apparatus 1 shown in FIG.
The incineration fly ash is melted by the arc type mixed ash melting furnace 2 and another incineration fly ash, that is, 12 ton / day incineration fly ash is melted by the oxygen burner type fly ash melting furnace 3 shown in FIG. Melts. As a result, 40.8 tons / day of molten slag is discharged from the bottom of the arc type mixed ash melting furnace 2,
From the hearth of the oxygen burner type fly ash melting furnace 3, 6.6ton /
The molten slag of the day is discharged, and both of these molten slags flow down to the water tank 8 of the common granulating and solidifying apparatus 4 shown in FIG. 2, and are solidified and crushed by rapid cooling.

[0013]

[Table 3]

Table 3 shows the characteristics of the arc type mixed ash melting furnace 2 and the oxygen burner type fly ash melting furnace 3 described above. As shown in FIGS. 2 and 4, the arc type mixed ash melting furnace 2 is supplied with three-phase AC power to three electrodes 6 suspended in the furnace body 5 and mixed by heat generated by arc discharge between the electrodes. The ash is melted to form a molten slag 7 at the furnace bottom. 10 is a charging chute for charging the mixed ash conveyed from the mixing and conveying device 1 into the furnace, 11 is a hopper for temporarily storing the incinerated ash taken out from the incinerator and the boiler, 12 is the reaction tower and the dust collector A hopper that temporarily stores incinerated fly ash extracted from Each of the hoppers 11 and 12 is provided at its discharge port with a fixed-quantity supply device. The incineration ash and the incineration fly ash are mixed at an expected ratio, and are mixed through a mixing and conveying device 1 and a charging chute 10 to form an arc type mixed ash melting furnace. 2 can be put in. In addition, a portion in contact with the molten slag 7 such as a lower side portion of the furnace body 5 is formed of a refractory brick containing silicon carbide (SiC) as a main component.

As shown in FIGS. 3 and 4, the oxygen burner type fly ash melting furnace 3 has an oxygen burner 21 provided on an upper wall portion of a furnace body 20 in a downward direction. As shown in FIGS. 5 and 6, the oxygen burner 21 includes a fuel supply nozzle 50, a combustion support oxygen supply nozzle 51, an incineration fly ash supply nozzle 52, and a support oxygen supply nozzle 53 in that order. They are arranged concentrically. Reference numeral 25 denotes a protection cylinder in which a flow path 26 for a purge gas is formed. The oxygen burner 21 is supplied with cooling water for protecting itself from overheating.

Reference numeral 27 denotes a hopper for holding dry incinerated fly ash; 28, a fly ash extracting device for quantitatively extracting the incinerated fly ash;
Reference numeral 9 denotes a compressor with a dryer provided to carry the incinerated fly ash to the oxygen burner 21 by gas. The incinerated fly ash is supplied to the oxygen burner 21 by the dry air fed from the compressor 29. In the oxygen burner 21, a high-temperature flame of about 2000 ° C. is formed downward in the furnace by a reaction with oxygen, and incineration fly ash is directly supplied and melted in the flame.
Then, the molten slag 30 is stored in the furnace bottom. The portion that contacts the molten slag 30 at the bottom or the like of the furnace body 20 is formed by magnesia-chromium (MgO, C _r2 O ₃₎ refractory bricks.

The molten slag 30 formed in the fly ash melting furnace 3 and the molten slag 7 formed in the mixed ash melting furnace 2 are both discharged from the side walls thereof and pass through the flow path 37 to form the granulated solidification apparatus shown in FIG. 4 falls into the water tank 8. Reference numeral 31 denotes an auxiliary heating electrode provided to prevent solidification of the molten slag near the outlet. Reference numeral 32 denotes a water spray nozzle provided at a lower portion inside the falling cylinder. In the water crushing and solidifying device 4, a conveyor 33 is disposed in a water tank 8, and crushed glass granular slag settled in the water tank 8 can be scraped out to a transport vehicle 34. In addition, 35 is a cooling water tank for circulating and using the water in the water tank 8, and 36 is a purification device. The granulated slag thus stored in the transport vehicle 34 is mixed into, for example, asphalt and is effectively used as a pavement material for roads.

As shown in FIG. 2, an exhaust gas discharge port 40 is formed in the ceiling of the mixed ash melting furnace 2, and the exhaust gas discharged therefrom is mixed with air supplied from a blower 41 to thereby reduce the exhaust gas. The exhaust gas is cooled to below the heat resistance temperature of the bag filter, and the cooled exhaust gas is sucked by the fan 46 to pass through the duct 42 to pass through the dust settling chamber 43, an exhaust gas collector 44 of a bag filter type, an exhaust gas cleaning device 47 and the like. It is discharged from the chimney 48 through 49.
The dust settling chamber 43 allows exhaust gas to flow into the vertical cylindrical container from above and supports a downward discharge pipe 45 into the container to drop and separate dust in the exhaust gas by its own weight. Further, an exhaust gas cleaning device 47 provided after the exhaust gas dust collector 44 includes a caustic soda (NaOH aqueous solution).
To neutralize HCl, SOx, etc. in the exhaust gas. The molten fly ash collected by the dust settling chamber 43 is returned to the hopper 12. Reference numeral 55 denotes a hopper for temporarily storing the molten fly ash collected by the exhaust gas dust collector 44. The molten fly ash stored in the hopper is kneaded with a chemical, stabilized, and then landfilled.

Further, an exhaust gas outlet 56 is formed in the upper part of the side wall of the oxygen burner type fly ash melting furnace 3, and the exhaust gas discharged therefrom is mixed with air supplied from a blower 57 to rapidly cool the exhaust gas. , Suppresses the re-generation of harmful substances such as dioxins. The exhaust gas is combined with the duct 42 and purified together with the exhaust gas from the arc type mixed ash melting furnace 2 through an exhaust gas treatment system 49 shown in FIG.

The exhaust gas from the arc type mixed ash melting furnace 2 and the exhaust gas from the oxygen burner type fly ash melting furnace 3 can be cooled independently, so that the exhaust gas from the high temperature melting furnace 3 can be further reduced. A large amount of air is mixed in, so that accurate temperature control can be performed, and thereafter, both exhaust gases are combined and processed by the common exhaust gas processing system 49, thereby reducing equipment costs.

FIG. 7 is a graph showing the relationship between the basicity of the contacting slag and the erosion rate ratio, that is, the erosion rate, for the refractory bricks A, B, C, and D having the compositions shown in Table 4. However, for the silicon carbide refractory bricks having the compositions of C and D used in the arc-type mixing and melting furnace of the present invention shown in Table 3, the erosion rate was reduced by the composition of A and B containing less silicon carbide. Slower than the refractory brick.

[0022]

[Table 4]

The furnace body 2 of the oxygen burner type fly ash melting furnace 3
In the case of 0, the portion that comes into contact with the molten slag 30 is formed of a highly basic refractory brick such as a magnesia-chromium-based refractory brick or a chrome-magnesia-based refractory brick. Improve. The furnace body 5 of the arc-type mixed ash melting furnace 2 is made of a refractory brick containing silicon carbide as a main component, thereby reducing equipment costs and costs required for maintenance such as replacement.

As described above, since the waste incineration residue melting facility of the present invention includes the mixed ash melting furnace 2 and the fly ash melting furnace 3, the mixed ash obtained by mixing the incinerated ash and the incinerated fly ash at an appropriate ratio is used. Melting in the mixed ash melting furnace 2 and melting the remaining incinerated fly ash in the fly ash melting furnace 3 to reduce and stabilize the volume of reduced incineration slag into reduced melting slag without storing any incinerated fly ash. Can be. Therefore, equipment costs can be reduced without requiring a large storage tank. In addition, since the high basicity fly ash is melted in the small fly ash melting furnace 3, the basicity of the molten slag of the mixed ash melting furnace 2 is suppressed, and the furnace body 5 has low to medium basicity and excellent corrosion resistance. It is possible to use a refractory material containing silicon carbide as a main component and to greatly reduce the maintenance cost.

[0025]

As described above, according to the waste incineration residue melting facility of the present invention, there is a beneficial effect that equipment costs and maintenance costs are reduced.

[Brief description of the drawings]

FIG. 1 is an overall flowchart of a waste incineration facility according to the present invention.

FIG. 2 is a system diagram of a waste incineration residue melting facility according to the present invention.

FIG. 3 is a system diagram of a fly ash melting furnace according to the present invention.

FIG. 4 is a plan view of a mixed ash melting furnace and a fly ash melting furnace according to the present invention.

FIG. 5 is a longitudinal sectional view of an oxygen burner according to the present invention.

FIG. 6 is an enlarged front view of the oxygen burner of FIG. 5;

FIG. 7 is a diagram showing the relationship between the melting rate of refractories and the basicity of molten slag.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mixing and conveying device 2 mixed ash melting furnace 3 fly ash melting furnace 4 granulating and solidifying device 5 furnace body 6 electrode 7 molten slag 8 water tank 20 furnace body 21 oxygen burner 30 molten slag 31 electrode 42 duct 43 dust sedimentation chamber 44 exhaust gas dust collector

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23J 15/00 F23J 15/00 K F23M 5/00 Z

Claims (3)

[Claims] 1. A mixed ash melting furnace in which incineration ash taken out of an incinerator and incineration fly ash taken out of an exhaust gas treatment system of the incinerator are mixed and melted at an appropriate ratio, and taken out of an exhaust gas treatment system of the incinerator. A fly ash melting furnace that supplies the burned fly ash to an oxygen burner by gas transfer and blows a high-temperature flame downward into the furnace from the oxygen burner with a supporting gas of 90% or more of oxygen to melt the burned fly ash; A waste incineration residue melting facility, characterized by comprising a water granulation and solidification device for dropping and solidifying and crushing molten slag accumulated at the bottoms of the mixed ash melting furnace and the fly ash melting furnace. 2. A facility for melting incineration residues according to claim 1, wherein the mixed ash melting furnace has a portion in contact with the molten slag formed of a refractory material containing silicon carbide as a main component. 3. An exhaust gas from a mixed ash melting furnace and an exhaust gas from a fly ash melting furnace are cooled independently, and then the two exhaust gases are combined and discharged through a common exhaust gas treatment system. Facility for melting waste residue from incineration described in 1.