JP3234189B2 - Method and apparatus for effective use of waste incineration fly ash - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a waste incineration fly ash or a waste combustion fly generated when incinerating or burning waste such as municipal waste, industrial waste, and solid fuel (RDF). The present invention relates to a method and an apparatus for effectively using ash (hereinafter simply referred to as incineration fly ash). In addition, solid waste fuel (RDF: Refuse Derived Fu)
El) refers to a fuel formed by adding a calcium compound to municipal waste, industrial waste, or the like that has been subjected to pretreatment such as drying, sorting, and crushing.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional waste incinerator exhaust gas treatment apparatus. The waste such as the refuse introduced into the waste incinerator 10 is completely burned at a high temperature, and the generated combustion exhaust gas is introduced into a gas cooling unit 12 composed of a gas cooling tower or a boiler, cooled, and further cooled by air. Preheater 1
4, the air is preheated, and a flue gas desalting agent such as lime is supplied to the cooled exhaust gas by a lime etc. feeder 16, and is introduced into the bag filter 18 and mainly discharged on the bag surface of the bag filter 18. Hydrogen chloride (HCl)
While harmful components such as gas are absorbed and removed, unreacted desalting chemicals and calcium chloride (Ca
Incinerated fly ash containing Cl ₂ ) is collected, and bag filter 18 is collected.
The treated exhaust gas from is discharged from the chimney 20.

As described above, the waste put into the waste incinerator 10 is completely burned at a high temperature, and heat is recovered from the generated combustion exhaust gas. At this time, the ash collected by each device such as the gas cooling unit 12 and the air preheater 14 and the dust collected by the dust collector such as the bag filter 18 are supplied to remove harmful components such as HCl contained in the exhaust gas. Used chemicals (unreacted chemicals and reaction products) collected together with incineration fly ash
These are combined as fly ash, which are treated as specially controlled waste by cement solidification, chelation, melting, etc. In addition, in the fly ash melting process, heavy metals and salts in the fly ash volatilize due to high temperature, so that exhaust gas treatment is required. Furthermore, since the high temperature treatment is performed at a temperature of 1000 ° C. or higher, there is also a problem that the furnace is damaged by the salts. appear. To prevent this, for example, JP-A-4-87676 discloses that a dust collector such as a cyclone is provided in a temperature range of 700 ° C. or higher after the waste incinerator outlet to selectively fly ash that does not contain heavy metals or salts. And a method of fusing it.

[0004]

There is a method of effectively using incinerated fly ash which is solidified and used for roadbed materials, etc. In the cement solidification method which is currently used for fly ash treatment, Even if the addition amount of cement is increased to about 30 wt%, the compressive strength of the solidified body is about 10 kgf / cm ² ,
It has not been used effectively. In the case of solidifying incineration fly ash using a hydration reaction, in conventional waste incinerators, fly ash generated in the incinerator is collected by each device after the furnace exit and collected together, so fly ash is collected. Contains a large amount of chemicals such as unreacted slaked lime supplied for the treatment of exhaust gas and used (reacted) chemicals, which is an obstacle to solidification and stabilization by hydration. Furthermore, since the conventional fly ash is collected after passing through a temperature range of 300 to 500 ° C., which is considered to be where dioxins are synthesized, dioxins are present in the fly ash. Further, in the melting treatment method described in JP-A-4-87676, it is necessary to separately treat fly ash containing a large amount of heavy metals and the like collected by an electric dust collector or a bag filter downstream of the inertial dust collector. is there.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a dust collector (cyclone, cyclone, etc.) between an outlet of a waste incinerator and a chemical injection position for exhaust gas treatment such as HCl removal. Bag filter, electric dust collector, etc.)
Fly ash (incinerated fly ash) that does not contain chemicals such as slaked lime and reacted chemicals is separated and collected from fly ash (desalting residue) that contains a large amount of unreacted chemicals and reacted chemicals. Ash to water,
It is an object of the present invention to provide a method and an apparatus for effectively utilizing waste incineration fly ash, in which a suitable additive (alkali agent) is added as required to solidify and stabilize by hydration reaction. Further, an object of the present invention is to provide a fly dust collector with a low content of dioxins by providing an appropriate dust collector between a waste incinerator outlet and a position where the gas temperature is 500 ° C. or higher. It is an object of the present invention to provide a method and an apparatus for effectively utilizing waste incineration fly ash in which ash is solidified and stabilized by a hydration reaction.

[0006]

Means for Solving the Problems To achieve the above object, a method for effectively using waste incineration fly ash according to the present invention comprises an alkaline earth metal compound contained in combustion exhaust gas discharged from a waste incinerator. Exhaust gas desalting agent of any one of the following and an alkali metal compound, and removing the hydrogen chloride gas in the exhaust gas. A dust collector is installed to collect incineration fly ash that does not contain a desalting agent, and a desalting agent is put into the exhaust gas downstream of the first dust collector, and a hydration reaction takes place in the second dust collector. The desalting residue containing the desalting agent and the reaction product that is unsuitable for solidification by ash is separated and collected from incineration fly ash that is suitable for solidification by hydration without the desalting agent. Only incinerated fly ash that does not contain desalting chemicals collected by a vessel is made by solidification by hydration As the use raw material is configured so as to effectively use (see FIGS. 1 to 3). As the waste incinerator, a fluidized bed furnace, a rotary kiln, a stoker furnace, or the like is used. In the above method, a centrifugal dust collector such as a cyclone, a bag filter, a filter dust collector, an electric dust collector, or the like is used as the first dust collector. Further, as the second dust collector, a bag filter, a filter type dust collector, an electric dust collector, or the like is used.

[0007] In the desalination residue collected by the second dust collector,
Unreacted desalting agent and reacted agent (reaction product)
(For example, 20 to 35% by weight in the case of desalination residue from a bag filter in an exhaust gas line of a fluidized bed incinerator). Therefore, a part of the desalination residue collected by the second dust collector should be configured to be used as an alkali agent for hydrating and solidifying incinerated fly ash that does not contain a necessary amount of the desalting agent. Is preferred. In this case, C as a desalting agent
Preferably, an a-type compound is used.

[0008] In the above method, in the process of cooling the exhaust gas,
Collect incineration fly ash before dioxins are synthesized
For this purpose, a first dust collector was installed between the waste incinerator outlet and the position where the exhaust gas temperature was 500 ° C or higher, and the incineration fly ash with low dioxin content and no desalting agent was used. With a desalting agent and
It is preferable that the desalting residue containing the reaction product is separated and collected (see FIGS. 1 and 2). in this case,
The upper limit of the gas temperature is the temperature at the outlet of the incinerator, for example, about 850 to 900 ° C. in the case of a fluidized bed incinerator. As the first dust collector, a centrifugal dust collector such as a cyclone is used. An example of this method is that the exhaust gas is cooled during the cooling process.
In order to collect incinerated fly ash before xins are synthesized,
A centrifugal dust collector, such as a cyclone, is installed as the first dust collector between the waste incineration outlet and the gas cooling section immediately after the waste incinerator outlet to reduce dioxin content and desalinate. Incinerated fly ash that does not contain chemicals is not resistant to solidification by hydration.
Of desalinating residue containing the suitable desalting agent and reaction product
Separate and collect (see FIG. 1). Also, as another example of this method , dioxins are used in the process of cooling exhaust gas.
In order to collect incineration fly ash before it is synthesized, a cyclone as a first dust collector is installed between the boiler superheater immediately after the waste incinerator outlet and the boiler evaporator immediately after this boiler superheater. Centrifugal dust collector, etc. to remove incinerated fly ash with a low dioxin content and no desalting agent into water.
Desalting agents and reaction products unsuitable for solidification by summation reaction
And separate from the desalting residue containing
reference).

Further, the method for effectively utilizing waste incineration fly ash according to the present invention is a method according to the above-mentioned [0006], wherein a first dust collector is provided immediately before a desalting agent charging position, and Unsuitable for solidification by hydration of incinerated fly ash that does not contain chemicals
Separation from desalination residues containing chemicals and reaction products
It is characterized in that it is collected after being collected (see FIG. 3). In this case, a bag filter, a filter-type dust collector, a centrifugal dust collector such as a cyclone, an electric dust collector, or the like is used as the first dust collector.

The apparatus for effectively utilizing waste incineration fly ash according to the present invention collects a chemical for desalinating either an alkaline earth metal compound or an alkali metal compound into flue gas discharged from a waste incinerator. Just before the dust,
In an exhaust gas treatment device that removes hydrogen chloride gas in exhaust gas and collects incineration fly ash containing a desalting agent and a reaction product, the incineration fly ash that does not contain a desalting agent is hydrated. Desalting chemicals and
To separate and collect from the desalination residue containing the reaction product ,
The first dust collector provided between the waste incinerator outlet and the desalination chemical charging position, and only the incineration fly ash that does not contain the desalination chemical collected by the first dust collector is watered. And a solid production apparatus for producing a solid by the sum reaction. In the method and apparatus of the present invention, the alkaline earth metal compound may be Ca (OH) ₂ , CaO, C
Powders or slurries such as aCO ₃ and dolomite are used. As the alkali metal compound, Na ₂ CO ₃ , Na
A powder such as OH, a slurry or an aqueous solution is used.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described for a case where a waste incinerator is a fluidized bed refuse incinerator with a large amount of fly ash. The present invention is not limited to the case, and can be applied to other incinerators such as a rotary kiln and a stoker furnace. FIG. 1 shows an apparatus for implementing a method for effectively utilizing waste incineration fly ash according to a first embodiment of the present invention.
In the present embodiment, a cyclone 26 is provided as a first dust collector between an outlet of a refuse incinerator 22 and a gas cooling unit 24 including a gas cooling tower or a boiler. Reference numeral 28 denotes a fluidized bed, and the temperature in the bed is, for example, about 600 ° C. A free board 30 has a temperature of, for example, about 850 to 900 ° C.

[0012] The refuse entered into the refuse incinerator 22 is 60
The fuel is burned in the fluidized bed 28 having a high temperature of about 0 ° C., and the unburned components completely burn at about 850 to 900 ° C. in the free board 30. The flue gas is introduced into the cyclone 26 and incinerated fly ash that does not contain a desalting agent is collected. The temperature of the exhaust gas passing through the cyclone 26 becomes approximately 700 ° C. or higher. Therefore, if the combustion state of the refuse incinerator 22 is good, incineration fly ash containing no dioxins can be obtained. Cyclone 2
The exhaust gas from 6 is introduced into a gas cooling unit 24 composed of a gas cooling tower or a boiler, and after being cooled, for example, around 400 ° C., is further introduced into an air preheater 32 to indirectly preheat air, and For example, lime or the like, for example, slaked lime, is introduced into the flue gas cooled to about 180 ° C. by the lime or the like feeder 34 and introduced into the bag filter 36, and HCl in the flue gas mainly on the surface of the bag of the bag filter 36.
And other harmful components are adsorbed and removed, and desalted residues containing unreacted slaked lime and reaction products such as calcium chloride are collected. The amount of this desalting residue is
Is significantly smaller than the amount of incinerated fly ash collected at the site.

The incinerated fly ash, which is low in dioxins and does not contain slaked lime, collected by the cyclone 26, is introduced into a solidified body producing apparatus 38 by a hydration reaction, and is treated with water or water and lime. (For example, slaked lime), kneaded and molded, and then cured, so that ettringite (3CaO.Al ₂ O) is formed by a hydration-solidification reaction.
_{3 · 3CaSO 4 · 32H 2 O} ) or the like to solidify to generate,
Solidified by hydration. Then, crush as necessary. The obtained solidified material is stable and has high strength (for example, compressive strength of about 100 kgf / cm ² ), and is effectively used as a civil engineering material such as a roadbed material and a building material. The apparatus for producing solidified body 38 by the above-mentioned hydration reaction comprises, for example, a kneader, a molding machine and a curing room, or comprises a kneader, a molding machine, a curing room and a crusher. It is preferable to add an alkali agent such as slaked lime at 10% by weight or less during kneading. When a Ca-based compound is used as the desalting agent, it is preferable to use a part of the desalting residue as an alkali agent at the time of kneading.

FIG. 2 shows an apparatus for carrying out a method for effectively utilizing waste incineration fly ash according to a second embodiment of the present invention. In this embodiment, a cyclone 26a is used as a first dust collector.
Is provided between the superheater 40 of the boiler and the evaporator 42 of the boiler, and the exhaust gas from the boiler evaporator 42 is introduced into the air preheater 32. The boiler superheater 4
The exhaust gas temperature at the outlet 0 is, for example, around 600 ° C., and the exhaust gas temperature at the inlet of the boiler evaporator 42 is, for example, around 500 ° C. Also in this case, since the temperature of the exhaust gas passing through the cyclone 26a is 500 ° C. or more, incinerated fly ash containing no dioxins can be obtained. Other configurations and operations are the same as those in the first embodiment.

FIG. 3 shows an apparatus for implementing a method for effectively utilizing incinerated fly ash according to a third embodiment of the present invention. In the present embodiment, a bag filter 44 is provided as a first dust collector immediately before a position where a chemical such as slaked lime is charged.
The exhaust gas from the refuse incinerator 22 passes through the gas cooling unit 24 and the air preheater 32, is cooled to, for example, about 180 ° C., is introduced into the bag filter 44 as the first dust collector, and has been used (reacted). An incinerated fly ash containing no chemicals and unreacted chemicals (chemicals remaining without reacting) is obtained. After a chemical such as slaked lime is added to the exhaust gas from the bag filter 44, it is introduced into the downstream bag filter 36. In the present embodiment, since fine ash can be collected by the upstream bag filter 44, the amount of incineration fly ash contained in the desalination residue collected by the downstream bag filter 36 is reduced, which is not suitable for solidification.
That is, there is an advantage that the amount of ash that is difficult to use effectively is reduced. Other configurations and operations are the same as those in the first embodiment.

[0016]

As described above, the present invention has the following effects. (1) Fly ash that does not contain slaked lime or other chemicals (incinerated fly ash)
And fly ash containing a large amount of chemicals and reaction products (desalting residue)
Is separated and collected, and the incinerated fly ash is solidified and stabilized as a target of the hydration-solidification reaction, so that the compressive strength is 100 kg.
A solidified body of f / cm ² or more can be obtained and can be effectively used as a roadbed material, a building material, and the like. (2) Since the incinerated fly ash collected by the first dust collector does not contain chemicals and reaction products, it is necessary to pre-treat the fly ash when hydrating and solidifying the incinerated fly ash. No or less pre-processing. (3) When fly ash is collected at a comparatively low temperature (below 300 ° C), most of heavy metals are collected in fly ash, but in the hydration-solidification reaction, heavy metals are volatilized, unlike melting treatment. It is contained in a solidified body without being treated and at the same time is treated safely, and the emission of ash containing a large amount of heavy metals is eliminated. (4) When a dust collector is provided in a temperature range of 500 ° C. or higher, incineration fly ash is collected before dioxins are synthesized in a cooling process, and is not hydrated by being hydrated and solidified. A safe solid can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for implementing a method for effectively utilizing waste incineration fly ash according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an apparatus for implementing a method for effectively utilizing waste incineration fly ash according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of an apparatus that implements a method for effectively using waste incineration fly ash according to a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing an example of a conventional waste incinerator exhaust gas treatment apparatus.

[Explanation of symbols]

 Reference Signs List 10 waste incinerator 12 gas cooling unit consisting of gas cooling tower or boiler 14 air preheater 16 lime etc. feeder 18 bag filter 20 chimney 22 refuse incinerator 24 gas cooling unit consisting of gas cooling tower or boiler 26, 26a Cyclone ( First dust collector) 28 Fluidized bed 30 Free board 32 Air preheater 34 Lime etc. feeder 36 Bag filter (second dust collector) 38 Solidified body manufacturing device 40 Boiler superheater 42 Boiler evaporator 44 Bag filter (First Dust collector)

──────────────────────────────────────────────────続 き Continuation of front page (51) Int.Cl. ⁷ Identification symbol FIF23G 5/30 ZAB B01D 53/34 134A (56) References JP-A-1-310722 (JP, A) JP-A-3-179 (JP, A) JP-A-1-155936 (JP, A) JP-A-8-117549 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B09B 3/00 B01D 53 / 68 F23G 5/30

Claims (7)

(57) [Claims] Claims: 1. An agent for desalinating an exhaust gas of one of an alkaline earth metal compound and an alkali metal compound into a flue gas discharged from a waste incinerator to remove hydrogen chloride gas in the flue gas. In the exhaust gas treatment method, a first dust collector is provided between the waste incinerator outlet and the desalting agent charging position to collect incineration fly ash that does not contain the desalting agent, A desalinating agent is introduced into the exhaust gas downstream of the vessel, and a desalinating agent unsuitable for solidification by hydration and a desalinating residue containing a reaction product in a second precipitator are deionized water containing no desalinating agent. It is separated from incinerated fly ash suitable for solidification by the summation reaction and collected separately, and only incinerated fly ash that does not contain a desalting agent collected by the first dust collector is used as a raw material for solidified body production by the hydration reaction and
Effective utilization of waste effectively use the method of incineration fly ash, characterized by Te. 2. The method for effectively utilizing waste incineration fly ash according to claim 1, wherein a part of the desalination residue is used as an alkali agent for hydrating and solidifying the incineration fly ash that does not contain a desalting agent. 3. The process of combining dioxins in the process of cooling exhaust gas.
In order to collect the incineration fly ash before being formed, a first dust collector is provided between the waste incinerator outlet and the position where the exhaust gas temperature is 500 ° C. or higher, and the content of dioxins is low.
And, the incineration fly ash containing no drug for desalination, the hydration reaction
Desalting agents and reaction products not suitable for solidification
3. The method for effectively utilizing waste incineration fly ash according to claim 1 or 2, wherein the ashes are separated and collected. 4. The process of combining dioxins in the process of cooling exhaust gas.
In order to collect incineration fly ash before being formed, a centrifugal dust collector is provided as a first dust collector between a waste incineration outlet and a gas cooling unit immediately after the waste incinerator outlet, Desalting chemicals and reactions unsuitable for solidification by hydration of incinerated fly ash with low content of dioxins and no desalting chemicals
Claim 1 which collects separately from the desalination residue containing a product .
2. Effective use method of waste incineration fly ash according to 2 or 3. 5. A process for cooling dioxins in the process of cooling exhaust gas.
In order to collect incineration fly ash before it is formed, centrifugal force acts as the first dust collector between the boiler superheater immediately after the waste incinerator outlet and the boiler evaporator immediately after this boiler superheater. A dust collector is installed to solidify the incinerated fly ash with low dioxin content and no desalting agent by hydration.
What are undesired desalting chemicals and desalting residues containing reaction products?
4. The method for effectively utilizing waste incineration fly ash according to claim 1, 2 or 3, wherein the ashes are separated and collected. 6. The first collecting dust disposed directly in front of the medicine input position for desalting, the incineration fly ash containing no drug for desalination, the hydration reaction
Contains undesired desalting agents and reaction products
3. The method for effectively utilizing waste incineration fly ash according to claim 1 or 2, wherein the incineration fly ash is separated and collected from the desalination residue . 7. A flue gas desalting agent of one of an alkaline earth metal compound and an alkali metal compound is injected into a flue gas discharged from a waste incinerator immediately before a dust collector, and In an exhaust gas treatment device that removes hydrogen chloride gas and collects incineration fly ash containing a desalting agent and a reaction product, the incineration fly ash that does not contain a desalting agent is solidified by a hydration reaction.
Desalting residue containing undesired chemicals and reaction products
Is the first dust collector provided between the waste incinerator outlet and the desalting agent input position to separate and collect, and the desalination collected by the first dust collector An apparatus for effectively utilizing waste incineration fly ash, comprising: a solidified body manufacturing apparatus for converting only incinerated fly ash containing no chemical into a solidified body by a hydration reaction.