JP2002186933A - Method and system for gasification melting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To utilize dioxins instead of emitting into the environment and reduce a quantity for landfill disposal while decreasing a running cost. SOLUTION: By supplying slaked lime to the exhaust gas from a melting furnace 8, the primary dust collected at a prior stage dust collector is discharged out of a process line which mainly contains reaction products of slaked lime with HCl an SOX in the exhaust gas and ash containing nonaqueous components. As a substitute for high priced activated carbon, a part of carbon-containing fly ash generated in a gasification furnace 2 is supplied to the exhaust gas which has passed through the prior stage dust collector, and the secondary dust collected at a later stage dust collector containing reaction products of dioxins in the exhaust gas with the carbon-containing fly ash is supplied to the melting furnace 8. The secondary dust containing dioxins is used as heat source for the melting furnace 8, and is burnt and decomposed. The secondary dust to be generated much compared with that to be generated through the use of activated carbon is disposed of within the process line instead of being discharged out of the process line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasification and melting method for gasifying and melting combustibles and a gasification and melting system.

[0002]

2. Description of the Related Art Waste gas is gasified in a gasification furnace, and carbon-containing fly ash and flammable gas generated by the gasification are introduced into a melting furnace, and the gas is used to melt the carbon-containing fly ash in the melting furnace. Chemical fusing systems are known. This gasification and melting system is provided with an exhaust gas treatment facility that treats exhaust gas discharged from a melting furnace to release it to the atmosphere.

[0003] This exhaust gas treatment equipment is provided with a dust collector connected to an exhaust gas line of a melting furnace, and by supplying slaked lime and activated carbon to the exhaust gas in the preceding stage of the dust collector, the HCl and SO _X in the exhaust gas react with slaked lime. At the same time, the dioxin in the exhaust gas is reacted with the activated carbon, and dust containing these reaction products is separated from the exhaust gas by a dust collector and collected. Then, the gas collecting dust product was isolated in this dust collector is released dioxins, HCl, into the atmosphere as a substantially harmless gases compatible with harmful substances are removed environmental standards such as SO _X, whereas, catching dust collector The collected dust contains the above-mentioned harmful substances and is disposed of as a specially managed waste by mixing it with cement, chelate, etc. in accordance with laws and regulations.

In such an exhaust gas treatment facility, since the amount of landfill disposal is large, a two-stage dust collector is connected in series to the exhaust gas line of the melting furnace, and the first stage dust collector constitutes a water-insoluble composition (slag composition). SiO ₂ , Al ₂ O ₃ , CaO,
Ash containing ash containing MgO or the like) is collected, and the collected dust is supplied to a melting furnace to improve the slag conversion rate, and the exhaust gas from which the dust is separated by the first-stage dust collector is collected. Slaked lime and activated carbon are supplied at the front stage of the second-stage dust collector, and dust containing the reaction product is collected by the second-stage dust collector, and dioxin collected by the second-stage dust collector is A product that reduces the amount of landfill disposal compared to a single-stage dust collector by mixing landfill containing harmful substances such as HCl and SO _X with cement and chelate for landfill disposal It is becoming.

[0005]

As described above, the two-stage dust collection system in which the dust collector is connected in two stages in series with the exhaust gas line of the melting furnace is different from the one-stage dust collection system in which the dust collector is connected in a single stage. As a result, the amount of dioxin, which tends to be more strictly regulated, is released to the environment as in the case of the single-stage dust collection system.

Further, since an expensive treatment agent called activated carbon is used as a dioxin treatment agent (reactant with dioxin: dioxin adsorbent), there has been a problem that running costs are increased.

Here, Japanese Patent Application Laid-Open No. Hei 9-112855 describes a one-stage dust collection method, in which fly ash (char) generated in an incinerator is supplied to exhaust gas instead of activated carbon, and the fly ash is supplied to the fly ash. A method of reacting dioxin and collecting the reaction product with a dust collector is disclosed.

Therefore, in order to reduce the running cost in the two-stage dust collection system, it is conceivable to use fly ash instead of activated carbon. However, the reaction product of fly ash and dioxin is collected in the second stage dust collector. There is no change in the environmental release of dioxin in the form of dust and landfill.In addition, fly ash requires a larger amount than activated carbon, so there is a problem that the amount of landfill mixed with cement or chelate increases. .

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is possible to reduce the amount of landfill disposal by effectively utilizing dioxin without releasing it to the environment while reducing running costs. It is an object to provide a melting method and a gasification melting system.

[0010]

A gasification and melting method according to the present invention is directed to a gasification and melting method in which combustibles are gasified in a gasification furnace and the carbon-containing fly ash produced by the gasification is melted in a melting furnace. Supplying slaked lime to exhaust gas discharged from a melting furnace, separating and collecting dust containing reaction products with slaked lime from the supplied slaked lime as a first dust collector, While discharging the collected dust out of the system, a part of the carbon-containing fly ash is supplied to the exhaust gas from which the first collected dust is separated, and the carbon-containing fly ash is supplied from the supplied exhaust ash. It is characterized in that dust containing a reaction product with ash is separated and collected as second dust, and the second dust is supplied to a melting furnace.

A gasification and melting system according to the present invention includes a gasification furnace for gasifying combustibles and a melting furnace for melting carbon-containing fly ash produced by gasification of the gasification furnace. In a melting system, a slaked lime supply device that supplies slaked lime to exhaust gas discharged from a melting furnace, and a dust containing a reaction product of slaked lime with the slaked lime supplied is separated and collected as a first dust collection material A first dust collector, a dust discharge line for discharging the first dust outside the system, and a part of the carbon-containing fly ash to the exhaust gas from which the first dust is separated. A carbon-containing fly ash supply device, a second dust collector that separates and collects dust containing a reaction product of the carbon-containing fly ash from the exhaust gas supplied with the carbon-containing fly ash, as a second dust collector, Dust supply for supplying the second dust to the melting furnace Equipped and in.

According to the gasification and melting method and the gasification and melting system, slaked lime is supplied to the exhaust gas from the melting furnace, and the reaction product between HCl and SO _X in the exhaust gas and slaked lime in the exhaust gas in the former stage is collected. While dust mainly composed of ash containing a water-insoluble composition is collected as a first dust collection material and discharged out of the system and is disposed of, for example, in a landfill, the gasification furnace converts the exhaust gas that has passed through the preceding dust collection into a gasification furnace. A part of the carbon-containing fly ash generated in the above is supplied, and the dust containing the reaction product of dioxin and the carbon-containing fly ash in the exhaust gas is collected and melted as a second dust in the subsequent dust collection. Supplied to the furnace. As described above, since the carbon-containing fly ash is used as a dioxin treating agent, it is not necessary to purchase expensive activated carbon, and the second dust containing dioxin is supplied to the melting furnace. The second dust containing dioxin is used as a heat source of the melting furnace and burned and decomposed, and the second dust generated in a larger amount than when activated carbon is supplied is discharged out of the system. Without being processed in the system.

[0013] Here, when a part of the slaked lime is supplied to the exhaust gas from which the first dust is separated, the amount of the first dust is reduced, discharged to the outside of the system and, for example, landfilled. The amount is reduced.

When a part of the slaked lime is supplied to the exhaust gas from which the first dust is separated, slaked lime containing a reaction product with the slaked lime is collected as a second dust and collected in the melting furnace. Supplied to It is preferable that the melting point of the slaked lime be adjusted by supplying a melting point depressant to the second dust collected to be supplied to the melting furnace in order to increase the melting point of the melt.

[0015] Further, when a separation aid is supplied to the exhaust gas from which the first dust is separated, in addition to a part of the carbon-containing fly ash, a reaction product with the carbon-containing fly ash and a carbon-containing fly ash are supplied. After the ash is collected, it is peeled off well and supplied to the melting furnace.

If activated carbon is supplied to the exhaust gas from which the first dust is separated in addition to part of the carbon-containing fly ash, dioxin in the exhaust gas reacts with activated carbon having excellent reactivity. The reaction products are further collected as a second precipitant, and the dioxin level in the gas is further reduced.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a gasification and melting system to which the gasification and melting method according to the present invention is applied will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram showing a gasification and melting system according to the present invention.

This gasification and melting system is a system for waste such as general waste and industrial waste.
As shown in FIG. 1, a gasification furnace 2 of, for example, a fluidized bed type, for pyrolyzing and gasifying waste supplied through a waste supply line 1 is provided. The gasification furnace 2 pyrolyzes refuse at a temperature of about 900 ° C. under a predetermined pressure to generate flammable pyrolysis gas and carbon-containing fly ash. The gasification furnace 2 is connected to a solid-gas separation device 4 such as a cyclone through a line 3 for discharging a pyrolysis gas and carbon-containing fly ash accompanying the pyrolysis gas.

The solid-gas separator 4 separates the pyrolysis gas and carbon-containing fly ash to be introduced. A fly ash storage tank 6 is connected to the solid-gas separation device 4 via a line 5 for discharging carbon-containing fly ash, and a line 7 for discharging pyrolysis gas.
Is connected to a melting furnace 8 such as a rotary kiln.

The fly ash storage tank 6 stores the introduced fly ash containing carbon. The fly ash storage tank 6 is connected to the melting furnace 8 via a line 18 for discharging the stored carbon-containing fly ash, and a decomposition / activation furnace 12a via a line 19 that branches off in the middle of the line 18. Is connected. Line 18
At the branch position 20, the carbon-containing fly ash is sorted. In the present embodiment, 3/4 of the total amount is assigned to the line 18 and 1/4 of the entire amount is assigned to the line 19.

The melting furnace 8 uses the pyrolysis gas to be introduced as a fuel at a temperature of about 1200 to 1300 ° C. to melt and slag the carbon-containing fly ash which is simultaneously introduced. A line 21 is connected to the melting furnace 8 as an exhaust gas line for discharging exhaust gas containing fly ash generated by combustion and melting. The line 21 is connected to the exhaust gas cooling device 9 and the first The dust collector 10 and the second dust collector 11 are interposed in this order in this order.

The exhaust gas cooling device 9 cools the introduced exhaust gas to a temperature of about 200 ° C. and simultaneously recovers heat. This recovered heat is supplied to another system and used effectively.

First dust collector 10 and second dust collector 11
Separates and collects dust having a predetermined size or more from the exhaust gas to be introduced, and supplies the separated gas to a subsequent stage.

A slaked lime supply device 13 is connected to a line 21a between the exhaust gas cooling device 9 and the first dust collector 10 in the line 21. The slaked lime supply device 13 includes a slaked lime storage tank 13a and a line 13b serving as a slaked lime supply line for supplying slaked lime in the slaked lime storage tank 13a to the exhaust gas of the line 21a by spraying.

The line 21b between the first dust collector 10 and the second dust collector 11 in the line 21 has
The activation furnace 12a is connected. The decomposition / activation furnace 12a is capable of decomposing a part of the carbon-containing fly ash (1/4 of the total amount in the present embodiment) introduced through the line 19 and decomposing and activating surface deposits. After the conversion process,
The treated carbon-containing fly ash is sprayed and supplied to the exhaust gas of the line 21b by a line 12b as a carbon-containing fly ash supply line. Therefore, the line 19, the decomposition / activation furnace 12a that also functions as a carbon-containing fly ash storage tank, and the line 12b supply the carbon-containing fly ash to the exhaust gas from which the first dust is separated by the first dust collector. This corresponds to the carbon-containing fly ash supply device 12.

The stripping aid supplying device 15 is connected to the line 21b. This stripping aid supply device 1
5 is a separation tank for storing a separation aid such as diatomaceous earth, and a separation aid for spraying the separation aid of the separation aid storage tank 15a onto the exhaust gas to which the carbon-containing fly ash of the line 21b has been supplied. And a line 15b as an auxiliary agent supply line. The release aid may be supplied simultaneously with the carbon-containing fly ash at the same position.

Further, an activated carbon supply device 14 is connected to a line 12b constituting the carbon-containing fly ash supply device 12. The activated carbon supply device 14 includes an activated carbon storage tank 14a and an activated carbon storage tank 14a.
And a line 14b as an activated carbon supply line for merging with the carbon-containing fly ash 2b.

The first dust collector 10 has the first dust collector.
A second dust collection line for discharging the first dust collected by the dust collector 10 to the outside of the system for landfill disposal
3 are connected.

The second dust collector 11 is connected to a line 24 serving as a dust supply line for supplying the second dust collected by the second dust collector 11 to the melting furnace 8. A line 25 is connected to discharge the gas from which the second dust is separated by the second dust collector 11 to the atmosphere.

Next, the operation of the gasification and melting system configured as described above will be described. The refuse to be charged is pyrolyzed and gasified in the gasification furnace 2, and the pyrolysis gas and carbon-containing fly ash generated at this time are separated by the solid-gas separation device 4. Introduced into the melting furnace 8,
The pyrolysis gas is burned in the melting furnace 8 and the carbon-containing fly ash is melted.

Exhaust gas generated by combustion and melting in the melting furnace 8 is cooled to a predetermined temperature by a gas cooling device 9, and slaked lime is supplied to the exhaust gas by a slaked lime supply device 13. By supplying this slaked lime, HCl and SO _X in the exhaust gas
Reacts with slaked lime to produce a reaction product.

In the first dust collector 10, this slaked lime and HC
1, a dust mainly composed of ash containing a reaction product with SO _X and a water-insoluble composition (composition of SiO ₂ , Al ₂ O ₃ , CaO, MgO, etc. constituting a slag composition) Collected as. Since the collected first dust contains slaked lime having high releasability, it is well separated and discharged to the outside of the system. Since the first dust contains harmful substances such as HCl and SO _X , it is disposed as a specially controlled waste by mixing with cement, chelate or the like in accordance with laws and regulations.

On the other hand, a part of the carbon-containing fly ash is subjected to a decomposition treatment and an activation treatment in a decomposition / activation furnace 12a, and the carbon-containing fly ash subjected to this treatment is converted into a carbon containing the decomposition / activation furnace 12a. The contained fly ash supply device 12 supplies the first dust collected by the first dust collector 10 to the exhaust gas separated. By supplying the carbon-containing fly ash, dioxin in the exhaust gas reacts with the carbon-containing fly ash to generate a reaction product.

At the same time as or after the reaction product of the carbon-containing fly ash and dioxin is produced, the stripping assistant is supplied to the exhaust gas of the line 21b by the stripping assistant supply unit 15.

In the second dust collector 11, dust containing a reaction product of carbon-containing fly ash and dioxin is collected as a second dust collector. Since the collected second dust collected contains a separation aid, even if the dust collection surface is a cloth made of cloth or the like, the collected second dust is satisfactorily separated and supplied to the melting furnace 8.

In the melting furnace 8, the second dust containing dioxin is used as a heat source of the melting furnace 8 without being released to the environment, and the dioxin is burned and decomposed.

On the other hand, the gas from which dioxin has been separated by the second dust collector 11 is released to the atmosphere as a substantially harmless gas that meets environmental standards.

As described above, in the present embodiment, since carbon-containing fly ash is used as a dioxin treatment agent, it is not necessary to purchase expensive activated carbon, and it is possible to reduce running costs. . In addition, since the second dust containing dioxin is supplied to the melting furnace 8, the second dust containing dioxin is used as a heat source of the melting furnace 8, and the dioxin is burned and decomposed to convert the dioxin. Will not release to the environment. In addition, compared to the case where activated carbon is supplied for dioxin adsorption, the second dust generated in a larger amount is treated in the system without being discharged to the outside of the system, so the amount of landfill disposal can be reduced. It has been.

Here, when the concentration of dioxin in the gas discharged to the atmosphere after the second dust collector 11 is higher than a desired level, the first dust collector 10 separates the first dust. Activated carbon may be supplied to the exhaust gas in addition to part of the carbon-containing fly ash by the activated carbon supply device 14 as an auxiliary. By the supplementary supply of the activated carbon, dioxin in the exhaust gas reacts with the activated carbon having excellent reactivity, and the reaction product is further collected by the second dust collector 11 as the second dust, and released to the atmosphere. It is possible to further reduce the dioxin level in the gas to be used.

FIG. 2 is a schematic structural view showing another gasification and melting system according to the present invention. This gasification and melting system is different from the gasification and melting system of FIG. 1 in that a line 13 as a slaked lime supply line constituting the slaked lime supply device 13 is provided.
b, a line 13c is provided as a second slaked lime supply line connected to the line 21b.
Is that a melting point depressant supply device 16 is connected to a line 24 as a dust collection supply line for supplying a second dust collection.

The line 13c is used to transfer a part of slaked lime supplied to the line 21a via the line 13b.
b.

The melting point depressant supply device 16 adds a melting point depressant storage tank 16 a such as silica sand to the second dust collected in the line 24. And a line 16b as a melting point depressant supply line. In addition, as a melting point depressant, for example, a glass material or the like can be used in addition to silica sand.

In such a gasification and melting system, a part of slaked lime is supplied to the line 21b, so that the amount of slaked lime supplied to the line 21a is reduced. For this reason, the amount of the first dust collected by the first dust collector 10 is reduced as compared with the gasification and melting system of FIG. 1, and the amount of landfill disposal is reduced.

On the other hand, since part of the slaked lime is supplied to the line 21b, the supply of the slaked lime causes the first dust collector 1
HCl the first dust collection thereof by 0 remains in the exhaust gas which has been separated, the reaction product reacts with SO _X and slaked lime is generated in the second dust collector 11, the carbon-containing fly ash and dioxins described above In addition to the dust containing the reaction product of lime, the reaction product of slaked lime with HCl and SO _X is collected as the second dust. Since the second collected dust contains slaked lime having a high peeling property, even if the dust collecting surface is a filter cloth made of cloth or the like, the second collected dust is well separated and supplied to the melting furnace 8. For this reason, the release aid supply device 15 of FIG. 1 is not required.

A melting point depressant is supplied by the melting point depressant supply device 16 to the second dust collected in the melting furnace 8. The supply of the melting point depressant prevents the melting point of the molten material from rising due to slaked lime, and stabilizes the melting.

Then, in the melting furnace 8, dioxin, H
The second dust containing Cl and SO _X is used as a heat source of the melting furnace 8 without being released to the environment, and dioxin, HCl and SO _X are burned and decomposed.

In such a gasification and melting system, FIG.
It is possible to obtain the same effect as that of the gasification and melting system of FIG.
There is an effect that the stripping aid supplying device 15 is unnecessary.

As described above, the present invention has been specifically described based on the embodiments. However, the present invention is not limited to the above embodiments. For example, in the above embodiments, the function as a dioxin treating agent is sufficiently improved. Although the carbon-containing fly ash supply device 12 is configured to include the decomposition / activation furnace 12a, the decomposition / activation furnace 12a may be omitted if there is no significant problem in function.

Further, in the gasification and melting system shown in FIG. 2, the peeling aid supplying device 15 shown in FIG. 1 is not required.
In order to promote the separation of the second dust collection material in the dust collector 11 of FIG.

Further, in the above embodiment, the object to be gasified and melted is described as refuse. However, the present invention is not limited to refuse. good.

[0051]

The gasification melting method and gasification melting system according to the present invention use carbon-containing fly ash as a dioxin treatment agent, so that expensive activated carbon does not need to be purchased.
The running cost can be reduced, and the second dust containing dioxin is supplied to the melting furnace, so that the second dust containing dioxin is used as a heat source of the melting furnace and Dioxin is burned and decomposed,
Dioxin can be effectively used without releasing it to the environment. In addition, the second dust collected in a larger amount than when activated carbon is supplied is treated in the system without being discharged to the outside of the system. Therefore, the amount of landfill disposal can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a gasification and melting system according to the present invention.

FIG. 2 is a schematic configuration diagram showing another gasification and melting system according to the present invention.

[Explanation of symbols]

2 gasifier, 8 melting furnace, 10 first dust collector, 11
... second dust collector, 12 ... carbon-containing fly ash supply device, 12a
... Decomposition / activation furnace (carbon-containing fly ash storage tank), 12b ... Carbon-containing fly ash supply line, 13 ... Slaked lime supply device, 13a
... Slaked lime storage tank, 13b ... Slaked lime supply line, 13c ...
Second slaked lime supply line, 14 ... activated carbon supply device, 14
a ... activated carbon storage tank, 14b ... activated carbon supply line, 15 ...
Release aid supply device, 15a ... Release aid storage tank, 15b ...
Release aid supply line, 16 ... melting point depressant supply device, 16
a: melting point depressant storage tank, 16b: melting point depressant supply line, 21, 21a, 21b: exhaust gas line, 23: dust collection discharge line, 24: dust collection supply line.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F23G 5/16 ZAB B09B 3/00 303L F23J 1/00 ZAB 15/00 F23J 15/00 Z F term (Reference 3K061 AA11 AA24 AB02 AB03 AC01 BA04 BA10 FA21 NB06 NB20 3K070 DA03 DA05 DA16 DA24 DA27 DA75 3K078 AA04 AA10 BA26 CA02 CA24 4D004 AA37 AB07 CA29 CA47 CB31 CB42 CC11 DA02 DA03 DA06

Claims (6)

[Claims] 1. A gasification and melting method for gasifying combustibles in a gasification furnace and melting a carbon-containing fly ash generated by the gasification in a melting furnace, wherein slaked lime is supplied to exhaust gas discharged from the melting furnace. Then, dust containing the reaction product with the slaked lime is separated and collected as first dust from the exhaust gas to which the slaked lime is supplied, and the first dust is discharged outside the system. A part of the carbon-containing fly ash is supplied to the exhaust gas from which the first dust is separated, and a dust containing a reaction product of the carbon-containing fly ash with the carbon-containing fly ash is supplied from the supplied exhaust gas. Is separated and collected as a second dust collected, and the second dust collected is supplied to the melting furnace. 2. The method according to claim 1, wherein a part of the slaked lime is supplied to the exhaust gas from which the first dust is separated.
The gasification melting method as described in the above. 3. The gasification and melting method according to claim 2, wherein a melting point depressant is supplied to the second dust collected to be supplied to the melting furnace. 4. The flue gas from which the first dust collected has been separated is supplied with a peeling aid in addition to a part of the carbon-containing fly ash. 3. The gasification melting method according to 1. 5. The exhaust gas from which the first dust is separated is supplied with activated carbon as an aid in addition to a part of the carbon-containing fly ash. 3. The gasification melting method according to 1. 6. A gasification and melting system comprising a gasification furnace for gasifying combustibles and a melting furnace for melting carbon-containing fly ash produced by gasification of the gasification furnace, wherein the gas is discharged from the melting furnace. A slaked lime supply device for supplying slaked lime to exhaust gas to be discharged, and a first dust collector for separating and collecting dust containing a reaction product of the slaked lime with the slaked lime from the exhaust gas to which the slaked lime is supplied, as a first dust collector, A dust discharge line for discharging the first dust to the outside of the system; and a carbon-containing fly ash supply device for supplying a part of the carbon-containing fly ash to exhaust gas from which the first dust is separated. A second dust collector that separates and collects dust containing a reaction product of the carbon-containing fly ash from the exhaust gas supplied with the carbon-containing fly ash, as a second dust collector; A dust supply line for supplying dust to the melting furnace. Gasification melting system.