JP2003010634A - Method and installation for treating waste treatment exhaust gas and dust - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method for a waste treatment exhaust gas and dust capable of efficiently treating dust collected by a dust precipitator and of reducing the amount of dust to be subjected to the landfill treatment and to provide an installation therefor. SOLUTION: This method comprises steps of blowing a sodium type hydrogen chloride removing agent into the exhaust gas generated at an waste incinerator 10 from a hydrogen chloride removing agent blowing device 12, introducing the exhaust gas, in which the sodium type hydrogen chloride is blown, into the dust precipitator 13 to conduct the dust precipitation treatment and classifying the collected dust by a classifying means 20 to separate into the coarse grain content and the fine grain content. The separated two types of dust are treated by selecting a treatment method suitable for each of them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating waste gas and dust generated from a waste incinerator, a waste gasification and melting furnace, or a waste incineration residue melting furnace, and equipment therefor.

[0002]

2. Description of the Related Art Exhaust gas generated when incinerating wastes such as municipal waste contains harmful hydrogen chloride, so that hydrogen chloride is removed. In this hydrogen chloride removal treatment, generally, slaked lime powder is blown into the exhaust gas discharged from the incinerator to react with hydrogen chloride, and the exhaust gas blown with this slaked lime is introduced into a dust collector for dust collection processing and incineration. It collects the reaction product of slaked lime and hydrogen chloride together with soot and dust scattered from the furnace.

By the way, since the dust collected by the dust collector as described above contains harmful heavy metals such as lead and cadmium, the landfill disposal of the heavy metals is regulated by law. Depending on the method, a process that stabilizes harmful heavy metals in the dust so that they do not elute (hereinafter,
It shall be referred to as dust stabilization treatment). In many cases, a chemical kneading method, which is simple in processing operation, is adopted for the stabilization treatment of dust, but a part of the dust is processed by a melt solidification method.

In the chemical kneading method, a liquid chelating agent is added to the dust and kneaded, and the heavy metal in the dust is reacted with the liquid chelating agent to form a chelate complex insoluble in water.

In the melting and solidification method, dust is charged into a melting furnace maintained at a high temperature and melted, and the molten material is discharged and solidified to obtain a slag in which heavy metals are stabilized. The slag obtained by this melting treatment can be effectively used as a substitute for crushed stone or sand, which is a material for civil engineering.

However, in recent years, as it has become difficult to secure a landfill disposal site, there is a strong demand for reducing the amount of dust that must be disposed of in landfills. In such a situation, in the above-mentioned exhaust gas treatment method for collecting exhaust gas blown with slaked lime, since a large amount of calcium chloride and unreacted slaked lime produced by blowing slaked lime are mixed in the dust, it is harmful. The problem is that the amount of dust containing heavy metals increases.

As one of the methods for coping with this problem, it has been proposed to carry out dust collection treatment of exhaust gas in two stages. In this method, the soot dust scattered from the incinerator is collected and removed by the first-stage dust collector, and then slaked lime is blown into the exhaust gas from which the soot dust has been removed, and then the second-stage dust collector collects calcium chloride and Perform processing to collect unreacted slaked lime,
Discharge separately into dust containing heavy metals and dust not containing heavy metals.

[0008] Further, when disposing of dust, it is necessary to reduce the amount thereof, and further, reduction of environmental load and recycling of resources are being called for, and the method of disposing of dust is landfill disposal. There is a growing focus on methods for recovering valuable materials such as heavy metals from Japan.

In the above-mentioned heavy metal extraction treatment, an acid is added to dust to elute heavy metals such as zinc and lead, and then an alkali is added to the extract to precipitate hydroxide, or further water-soluble sulfurization is performed. The substance is added to precipitate the sulfide.
Then, the precipitate is separated by filtration to obtain a heavy metal concentrate that can be subjected to non-ferrous smelting.

[0010]

However, in the above conventional exhaust gas treatment, in order to sufficiently remove hydrogen chloride, an excessive amount of slaked lime has to be blown into the exhaust gas with respect to the concentration of hydrogen chloride. Unreacted slaked lime is mixed in the dust collected in, and a large amount of dust is discharged.

In order to prevent the emission of dust containing harmful heavy metals from increasing, as described above, the exhaust gas dust collection treatment should be performed.
By performing in stages, the dust containing harmful heavy metals and the dust not containing heavy metals generated by blowing in slaked lime can be discharged separately, but this method requires that two dust collectors be installed. Therefore, the exhaust gas treatment process becomes complicated. Further, in the second-stage dust collection treatment performed after the slaked lime is blown, the following problems caused by calcium chloride generated by the blown slaked lime occur, but this problem still remains.

Calcium chloride, which is a reaction product of hydrogen chloride and slaked lime, has a deliquescent property.
Measures must be taken to prevent moisture in the atmosphere from being absorbed by the calcium chloride in the dust adhering to the equipment. For this reason, particularly for dust collectors such as bag filters, it is necessary to heat the inside of the dust collector to keep it at a predetermined temperature or higher.

On the other hand, the chemical kneading method, which is a general method for stabilizing the dust collected by the dust collector, has the following problems. Since the liquid chelating agent is a very expensive drug, the cost of treating dust is very high. Furthermore, in the case of this treatment method, since a liquid chelating agent is added according to the content of harmful heavy metals such as lead, especially when treating dust with a large content of heavy metals, an expensive liquid chelating agent should be used. Since a large amount must be used, the dust disposal cost becomes higher.
Therefore, in terms of cost, this dust treatment method is not always an efficient method.

Further, the dust stabilization treatment by the melting and solidification method is a useful method capable of reliably stabilizing heavy metals, but since a melting furnace capable of holding at a high temperature must be provided, a large amount of equipment is required. Since the investment is required and a large amount of energy is required, the dust disposal cost is high. Therefore, in terms of cost, it cannot be said that the treatment of this dust is efficient.

Further, the dust generated from the municipal solid waste incinerator contains salts having a relatively low boiling point such as sodium chloride and potassium chloride. When the dust containing these salts is melted, the salts are Various troubles such as vaporization and adhesion to the treatment system of exhaust gas discharged from the melting furnace and formation of a molten salt layer on the molten material in the melting furnace occurred, and the operation of the melting furnace was stabilized. Not done

Further, the method of recovering the heavy metal in the dust by acid extraction has the following problems. The content of heavy metals in the dust discharged from the refuse incinerator is zinc is 0.
The amount of lead is about 5 to 2 mass% and the amount of lead is about 0.2 to 1 mass%.

The present invention solves the above problems, can efficiently treat the dust collected by the dust collector, and can reduce the amount of dust that must be disposed of in a landfill. An object of the present invention is to provide a method for treating exhaust gas and dust and a facility therefor.

[0018]

In order to solve the above problems, the method for treating waste gas and waste gas according to the invention of claim 1 is a waste incinerator, a waste gasification and melting furnace or a waste. Hydrogen chloride remover blowing process of blowing sodium hydrogen chloride remover into the exhaust gas generated from the incineration residue melting furnace, dust collecting process of collecting exhaust gas blown with sodium hydrogen chloride remover, and dust collecting dust The method is characterized by including a classification step of classifying and separating into coarse particles and fine particles.

According to a second aspect of the present invention, there is provided a waste treatment exhaust gas and dust treatment method, wherein in the first aspect of the invention, the sodium chloride removing agent blown in the hydrogen chloride removing agent blowing step has a particle size of 10 μm to 30 μm. It is characterized by being a powder of the sodium-based hydrogen chloride removing agent of.

According to a third aspect of the present invention, in the waste treatment exhaust gas and dust treatment method, the sodium chloride removing agent blown in the hydrogen chloride removing agent blowing step is in the form of an aqueous solution. It has a feature.

According to a fourth aspect of the present invention, there is provided a waste treatment exhaust gas and dust treatment method, wherein the coarse particles fractionated in the classification step in the invention according to any one of the first to third aspects are transferred to a stabilization treatment device. It is characterized in that it is sent to carry out stabilization treatment of heavy metals.

According to a fifth aspect of the present invention, there is provided a waste treatment exhaust gas and dust treatment method, wherein the coarse particles fractionated in the classification step are sent to a melting furnace in any one of the first to third aspects. It is characterized by melt processing.

According to a sixth aspect of the present invention, there is provided a method for treating waste gas and dust, wherein the coarse particle fraction sorted in the classification step is used as an exhaust gas source furnace in the first aspect of the invention. It is characterized by throwing in.

The waste treatment exhaust gas and dust treatment facility according to the invention of claim 7 removes sodium hydrogen chloride from the exhaust gas generated from the waste incinerator, the waste gasification and melting furnace, or the waste incineration residue melting furnace. Hydrogen chloride remover blowing device for blowing agent, dust collector for collecting exhaust gas blown with sodium hydrogen chloride remover, and dust collecting dust collected by this dust collector into coarse and fine particles It is characterized by having a classification means.

The present inventors can efficiently process the dust collected by the dust collector in the process leading up to the invention described above and reduce the amount of dust that must be disposed of in landfill. In order to find out a method of treating exhaust gas and a method of treating dust, various studies as described below were conducted.

First, when the properties of the dust generated from the waste incinerator were examined, it was found that the component composition differed depending on the particle size. This knowledge is based on the result of examining the content of various components by particle size in the dust collected by the bag filter of the municipal waste incineration facility of a certain municipality.
In this investigation, dust collected when the slaked lime powder for removing hydrogen chloride in the exhaust gas was not blown was examined, and the results are shown in FIGS. 4 to 6 and Table 1. It was 4 to 6 show the results of measuring the particle size distribution using a laser diffraction type particle size distribution measuring device and using isopropyl alcohol as a medium. Then, FIG. 4 is a diagram showing the results of measuring the particle size distribution of the dust collected by the bag filter. In addition, in FIGS. 5 and 6, the target particle size is 10 μm.
It is a figure which shows the particle size distribution of the coarse particle and the fine particle obtained at the time of classifying, and FIG. 5 shows the particle size distribution of the coarse particle mainly having a particle size of more than 10 μm. 6 is a particle size of 10 μm
The particle size distribution of the fine particles mainly consisting of the following is shown. In addition,
The particle size distribution in each of the above figures is shown by volume ratio. Table 1 shows the component analysis values of the above dusts.

[0027]

[Table 1]

According to FIGS. 4 to 6 and Table 1, the fine particles mainly having a particle size of 10 μm or less contain a large amount of heavy metals and chlorine (chloride) as compared with the coarse particles. Was 3 to 4 times the value of the coarse particles. On the other hand, Si,
A large amount of ash components such as Ca and Al were contained in coarse particles having a particle size of more than 10 μm, and were small in particles having a particle size of 10 μm or less. As a result, it was found that the fine particles of the dust generated from the waste incinerator by particle size were mainly heavy metals and salts, and the coarse particles were mainly ash components.

From this fact, the relatively coarse particles are Si,
Fly ash containing a large amount of ash components such as Ca and Al, and these were melted and vitrified in the high temperature part of the incinerator, and most of the fine particles vaporized salts and heavy metal compounds in the high temperature part of the incinerator. After that, it is considered to be condensed and solidified. And since the particles of salts and heavy metal compounds are produced by vaporization and are extremely fine particles,
It is considered that in the dust generated from the waste incinerator, the components are biased at a certain particle size.

As described above, since the dust generated from the waste incinerator has a component deviation at a certain particle size,
If the dust collected by the dust collector is classified using a certain particle size as a classification point, dust with a low salt and heavy metal content (coarse particles) and dust with a high salt and heavy metal content (fine particles) Can be sorted into

Therefore, if the dust can be separated into two types of dusts as described above, two types of dusts having different heavy metal contents can be obtained without performing the dust collection process of the exhaust gas in two steps. And since it is possible to select and treat the treatment method suitable for each of the two types of dust,
Dust generated from the waste incinerator can be efficiently treated comprehensively.

Of the two types of dust obtained as described above, for example, coarse-grained dust with a small content of heavy metals is to be landfilled, and fine-grained dust in which heavy metals are concentrated is used. If supplied for non-ferrous smelting, the amount of dust that must be stabilized and landfilled will be greatly reduced. At this time, if the method for stabilizing the coarse-grained dust is the chemical kneading method, the amount of the chemical agent such as the liquid chelating agent to be added can be small, so that the dust to be landfilled can be stabilized at a low cost. it can.

Further, when dust of coarse particles having a low heavy metal content is charged into the furnace of the exhaust gas source, the heavy metal compound is vaporized in the high temperature furnace, and further dioxins are decomposed.
If the dust from which heavy metals and dioxins have been removed is discharged together with the newly generated waste incineration ash and slag, it can be disposed of together with the above-mentioned discharge by the usual treatment method. Is simplified.

Further, if the coarse fraction dust having a small content of heavy metals is charged into the melting furnace of the waste incineration residue and subjected to the melting treatment by the separation as described above, the treatment amount decreases.
The equipment of the melting furnace can be downsized. Therefore, the amount of capital investment can be reduced and the energy consumption such as electric power can be reduced. Further, since the coarse-grained dust contains a small amount of salts, no troubles caused by the salts, which have conventionally occurred during the operation of the melting furnace, occur.

As described above, if the collected dust is classified,
Coarse-grained dust with a low content of salts and heavy metals and fine-grained dust with a high content of these can be separated, but when slaked lime is used as a hydrogen chloride remover, it is collected by a dust collector. Since calcium chloride having a deliquescent property is mixed into the collected dust, it is difficult to clarify the component classification as described above even if the dust is classified. That is, since the classification of dust is performed after being discharged from the dust collector, moisture absorption due to calcium chloride occurs in the process of discharging dust and the process of classification, and the particles of dust aggregate and the particle size distribution differs from the original state. , The relationship between the particle size of dust and the components becomes unclear.

Therefore, in the present invention, a sodium-based hydrogen chloride removing agent is blown into the exhaust gas, and the exhaust gas into which the hydrogen chloride removing agent is blown is introduced into a dust collector to perform dust collection treatment, and the dust collection dust is classified. Then, it is separated into a coarse particle containing a small amount of salts and heavy metals and a fine particle containing a large amount of salts and heavy metals.

When the dust generated from an ordinary refuse incinerator is separated into coarse particles and fine particles, as shown in Table 1, heavy metals and chlorine (chloride) are contained in large amounts in fine particles of 10 μm or less. Therefore, if the classification point is set to about 10 μm, most of the heavy metals are contained in the fine particle dust. However, in the waste treatment facility, 10 μm from dust collection dust
It is not preferable to perform a treatment for separating only particles of less than 10%, which is not preferable because the treatment efficiency is lowered. When the classification point is set to a value exceeding 30 μm, as shown in FIG. 4, the ratio of fine particles fractionated exceeds 50%, and the content of heavy metals decreases, which is not preferable.

Therefore, in the present invention, the sodium-based hydrogen chloride removing agent blown into the exhaust gas has a particle size of 1
A fine powder of about 0 μm to 30 μm is used so that the reaction product of the sodium-based hydrogen chloride removing agent and hydrogen chloride can be separated into fine particles of dust. When the sodium-based hydrogen chloride removing agent is sprayed in the form of an aqueous solution, it is necessary to blow the aqueous solution into a fine mist with a two-fluid nozzle or the like.

When a sodium compound is used as a hydrogen chloride removing agent, the reaction product with hydrogen chloride is sodium chloride, so that there is a problem related to moisture absorption of dust such as when calcium chloride is produced when slaked lime is blown. Does not occur. Also, since sodium compounds have good reactivity,
Hydrogen chloride can be sufficiently removed without blowing a large amount as in the case of blowing slaked lime. Therefore, the amount of dust emission is significantly reduced as compared with the case where slaked lime is used. In particular, when a fine powder sodium-based hydrogen chloride removing agent, for example, a sodium-based hydrogen chloride removing agent having a particle size of 10 μm to 30 μm is used, the reactivity is further improved, and the blowing amount of the sodium-based hydrogen chloride removing agent is increased. Is further reduced.

It is desirable to use finely pulverized sodium bicarbonate as the powdery sodium chloride removing agent. Since sodium bicarbonate does not have hygroscopicity, it can be easily made into a fine powder of about 10 μm by pulverizing it, and its storage and handling are easy.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in detail with reference to FIGS. In the present invention, when treating and disposing of the separated coarse and fine dust particles, it is possible to select a treatment method suitable for each dust,
FIGS. 1 to 3 show three main combinations of methods for treating coarse particles and fine particles.

FIG. 1 is a diagram showing an example according to the embodiment of the present invention. In FIG. 1, 10 is an incinerator for municipal waste,
11 is a temperature reducing tower that cools the exhaust gas discharged from the refuse incinerator to a temperature suitable for exhaust gas treatment, 12 is a hydrogen chloride remover blowing device that blows sodium bicarbonate powder into the path through which the exhaust gas flows, and 13 is exhaust gas collection. A bag filter for removing dust, 14 is an induced air blower, and 15 is a chimney. Further, 20 is an air-flow type fine powder classifying device for classifying the dust collected by the bag filter 13 into coarse particles having a low content of salts and heavy metals and fine particles having a high content of salts and heavy metals. is there.

In the waste gas treatment in the waste incinerator constructed as described above, after the waste gas generated in the waste incinerator 10 is recovered by the boiler or the like, it is introduced into the temperature reduction tower 11 and sprayed with water to be rapidly cooled. To be done. Powder of sodium bicarbonate is blown into the cooled exhaust gas from the hydrogen chloride remover blowing device 12, and the exhaust gas is introduced into the bag filter 13. The bag filter 13 collects the soot dust scattered from the incinerator 10 and the dust such as sodium chloride generated by the blowing of sodium bicarbonate together. The exhaust gas that has been subjected to the dust collecting process is further subjected to a process for further removing harmful gas, if necessary, and then released.

The sodium bicarbonate powder blown into the exhaust gas is finely pulverized to have a particle size at a classification point in the fine powder classifier 20 (a predetermined value within the range of 10 μm to 30 μm).

The hydrogen chloride removing agent blown into the exhaust gas is not limited to sodium bicarbonate powder, but may be an aqueous solution of sodium carbonate or sodium hydroxide. However, when these aqueous solutions are blown in, it is necessary to blow them into a fine mist with a two-fluid nozzle or the like. When the hydrogen chloride removing agent is blown in as an aqueous solution, it is blown into the temperature reducing tower 11 or the upstream portion of the temperature reducing tower 11 while also cooling the exhaust gas, and the exhaust gas treatment that also functions as part of the gas cooling is performed. Good.

The dust collected by the bag filter 13 is discharged and sent to the fine powder classifier 20. In this fine powder classifying device 20, the collected dust is classified into coarse particles and fine particles. At this time, the flow rate of air blown into the fine powder classifying device 20 and the solid-gas ratio are adjusted so that the classified particle size has a predetermined value. The particles are separated into fine particles each having a particle size of a predetermined value or less. In the classification process of dust discharged from a general waste incinerator, the classification point is set to about 10 μm to 30 μm, and the coarse particles and the fine particles are separated. If the classification point is set within the above range, most of the heavy metals contained in the dust discharged from the bag filter 13 are transferred to the fine particles, and the content of the heavy metals in the coarse particles becomes extremely low.

In the above exhaust gas treatment, the hydrogen chloride removing agent blown into the exhaust gas is sodium bicarbonate, and since moisture absorption of dust does not occur unlike when blowing slaked lime, dust particles are aggregated or heavy metal The fine particles of (1) adhere to the coarse particles and are separated as coarse particles, so that the relationship between the particle diameter and the components is not unclear. For this reason, most of the heavy metals move to fine particles.

The coarse-grained dust separated as described above is sent to the stabilization processing device 21 and then landfilled. In the stabilization processing device 21, a liquid chelating agent is added to the dust of coarse particles and kneaded to perform processing for stabilizing the heavy metal. In this stabilization process, as described above,
The heavy metal content of the coarse particles is very low, and the amount of the coarse particle dust to be further processed is about 70% of the dust collected by the dust collector as shown in Table 1. Therefore, the addition amount of the liquid chelating agent for stabilizing the heavy metal is small, and the dust to be landfilled can be stabilized at a low cost.

The fine particle dust containing a large amount of heavy metals is
Heavy metals such as lead and zinc are concentrated several times more than ordinary dust, so either supply this dust as a raw material for non-ferrous smelting, or extract this dust with acid to concentrate heavy metals. The product is processed and the concentrate is supplied as a non-ferrous smelting raw material. At this time, the fine dust is
As shown in Table 1, the amount is expected to be about 30% of the dust collected by the dust collector, and the content of heavy metals is increased several times higher than that of the dust. The extraction process is efficiently performed.

In FIG. 1, the method of treating the exhaust gas generated from the waste incinerator and the method of treating the dust have been described. Exhaust gas and dust generated from the waste gasification and melting furnace and the waste incineration residue melting furnace. Can be similarly processed.

FIG. 2 is a diagram showing another example according to the embodiment of the present invention. 2, parts having the same configurations as those in FIG. 1 are designated by the same reference numerals, and description thereof will be omitted. In this embodiment, a melting furnace 22 is provided,
The dust of coarse particles classified by the fine powder classifier 20 is melt-processed. The melting furnace 22 is a furnace for melting the waste incineration residue, and it is desirable to use a melting furnace of a type such as an electric resistance type ash melting furnace, a rotary surface melting furnace, etc. in which the charged dust is less scattered. .

In the waste treatment facility having the above-mentioned structure, the fine particle dust classified by the fine powder classifier 20 is supplied as a raw material for non-ferrous smelting, or is acid-extracted into a heavy metal concentrate. And then supplied as a non-ferrous smelting raw material. Further, the coarse-grained dust is charged into the melting furnace 22, discharged as a molten material, and then cooled and solidified to become slag.

In the melting treatment of the dust of the coarse particles, the treatment amount is expected to be about 70% of the collected dust, so that the equipment of the melting furnace can be downsized. Therefore, the amount of capital investment can be reduced and the energy consumption such as electric power can be reduced.

Further, since the coarse-grained dust contains a small amount of salts such as sodium chloride and potassium chloride having relatively low boiling points, the salts are vaporized and adhered to the molten exhaust gas treatment system or melted. The molten salt layer is not formed in the upper part of the molten material in the furnace, and there is no occurrence of the trouble that the current flows unevenly, and the stable operation of the melting furnace can be continued.

When the above-mentioned fine particle dust is subjected to acid extraction to extract heavy metals, if the residue is mixed with coarse particle dust and melted, the residue is reduced and slag is formed. By doing so, effective use becomes possible.

In FIG. 2, the method of treating the exhaust gas generated from the waste incinerator and the method of treating the dust have been described, but the exhaust gas and dust generated from the waste gasification and melting furnace can be treated in the same manner. . In addition, when treating the exhaust gas generated from the waste incineration residue melting furnace, the dust of coarse particles classified by the fine powder classifying device 20 is returned to the waste incineration residue melting furnace, and together with the waste incineration residue. Melt processing.

FIG. 3 is a diagram showing still another example according to the embodiment of the present invention. In FIG. 3, parts having the same configurations as in FIG. 1 are assigned the same reference numerals and explanations thereof are omitted. In this embodiment, coarse-grained dust classified by the fine-powder classifier 20 is loaded into the refuse incinerator 10. The fine dust is supplied as a raw material for non-ferrous smelting, or is extracted as an concentrate of heavy metals and then supplied as a non-ferrous smelting raw material.

When the heavy metal is extracted by acid-extracting fine particles of dust, the residue is mixed with coarse particles of dust and charged into the refuse incinerator 10. Further, the coarse particle dust and fine particle acid extraction residue charged into the refuse incinerator 10 are made into a muddy or slurry state, or preferably granulated to prevent dust generation outside and inside the furnace. It's better to keep it.

The coarse-grained dust charged in the waste hopper of the refuse incinerator 10 is thrown into the high temperature furnace together with the waste. In a high-temperature furnace, the heavy metal compounds in the charged coarse particles have the following behaviors depending on their forms, so that the coarse particle dust is stabilized. Heavy metal in the form of easily vaporized chloride and sodium chloride, which is a reaction product of sodium bicarbonate and hydrogen chloride, are vaporized again and scattered into the exhaust gas, and are removed from the injected dust. Further, heavy metals in the form of silicates and the like remain in the coarse particles as they are, but since silicates and the like are sparingly soluble compounds, there is no problem in the subsequent treatment of incinerated ash. Further, dioxins contained in the charged dust are decomposed and disappear in the high temperature furnace. Then, the dust from which heavy metals and dioxins have been removed is mixed with the newly generated incineration ash and discharged, and is disposed of in the same manner as normal incineration ash.

The heavy metal compound and sodium chloride vaporized in the furnace are condensed into fine particles and are collected by the bag filter 13 together with other dust. Then, the heavy metal compound and sodium chloride are classified by the fine powder classifying device 20, and mainly classified into fine particles. Therefore, most of the heavy metals scattered from the incinerator 10 are contained in the fine particles and discharged.

As described above, when the coarse-grained dust is sent to the refuse incinerator 10 and heated, the heavy metal compounds and sodium chloride contained in the coarse-grained portion are vaporized and recovered as the fine-grained portion. Therefore, according to the method shown in FIG. 3, coarse particles of dust can be disposed of in the same manner as ordinary incinerated ash, the heavy metal content of fine particles can be increased, and fine particles of dust can be extracted with an acid. The efficiency in obtaining the heavy metal concentrate is further improved.

Since the hydrogen chloride removing agent blown into the exhaust gas is sodium bicarbonate and the product thereof is sodium chloride, slaked lime is blown into the coarse-grained dust charged into the refuse incinerator 10. As is the case, it does not contain calcium chloride or unreacted slaked lime. Therefore, there is no problem that the incineration ash becomes hygroscopic or becomes alkaline.

In FIG. 3, the exhaust gas generation source is the waste incinerator, and the coarse dust particles classified by the fine powder classifier 20 are put into the waste incinerator and discharged together with the incinerator ash. Although the treatment method has been described, even when the exhaust gas generation source is a waste gasification melting furnace or a waste incineration residue melting furnace, the coarse-grain dust is introduced into the exhaust gas generation source furnace for processing. Also in this case, the charged coarse dust particles are heated in the high temperature furnace and are treated in the same manner as when they are charged into the waste incinerator.

[0064]

According to the present invention, a sodium-based hydrogen chloride removing agent is blown into the exhaust gas generated from a waste incinerator, and the collected dust is classified to obtain coarse particles with a low content of salts and heavy metals. Since it is separated into fine particles with a high content of salts and heavy metals, 2 dust collectors are installed to collect dust.
Even if the dust collection is not performed in stages, the dust collection can be separated into two types, that is, the dust having a high content of salts and heavy metals and the dust having a low content of heavy metals.

Since the hydrogen chloride removing agent is a sodium-based compound, troubles in the dust collecting step and the classification step due to moisture absorption of calcium chloride as in the case of blowing slaked lime do not occur.

Further, since it is possible to treat the separated two kinds of dusts by selecting a treatment method suitable for each, it is possible to reduce the dust that must be disposed of in the land, and at the same time, generate from the waste incinerator. Dust can be treated efficiently.

For example, coarse particles containing a small amount of heavy metals are treated as landfill dust, and fine particles containing a large amount of heavy metals are used as a raw material for non-ferrous metal smelting, or after acid extraction to make heavy metal concentrates. If supplied as a non-ferrous metal smelting raw material, the amount of dust to be landfilled can be reduced, and the stabilizing treatment cost can be significantly reduced.

Furthermore, when dust of coarse particles having a low content of heavy metals is charged into the furnace of a high temperature exhaust gas source, the heavy metal compounds are vaporized and dioxins are also decomposed.
Therefore, the coarse-grained dust can be disposed of as ordinary incinerated ash or slag, and the dust treatment is simplified.

Further, when the coarse-grained dust containing a small amount of heavy metals is melt-processed, the amount of processing is reduced, so that the equipment of the melting furnace can be downsized and the equipment investment can be reduced. At the same time, energy consumption such as electric power can be reduced. Further, since the coarse-grained dust has a low salt content, troubles due to salts that have occurred during the operation of the melting furnace do not occur, and the operation of the melting furnace is performed stably.

[Brief description of drawings]

FIG. 1 is a diagram showing an example according to an embodiment of the present invention.

FIG. 2 is a diagram showing another example according to the embodiment of the present invention.

FIG. 3 is a diagram showing still another example according to the embodiment of the present invention.

FIG. 4 is a diagram showing an example of a particle size distribution of dust collected by a bag filter of a municipal solid waste incineration facility.

FIG. 5 is a diagram showing a particle size distribution of coarse particles mainly having a particle size of more than 10 μm.

FIG. 6 shows a particle size distribution of fine particles mainly having a particle size of 10 μm or less.

[Explanation of symbols]

10 Garbage incinerator 11 Temperature reducing tower 12 Hydrogen chloride remover blowing device 13 Bug filter 20 Air flow type fine powder classifier 21 Stabilizer 22 Melting furnace

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) B07B 7/08 F23J 1/00 B 4D021 B09B 3/00 B01D 53/34 134A 4D054 F23G 5/02 ZAB 4D058 7/00 103 B09B 3/00 304G F23J 1/00 303L 15/00 F23J 15/00 Z B03C 3/01 B (72) Inventor Hiroshi Yamamoto 1-1-2 Marunouchi, Chiyoda-ku, Tokyo F-term in Nihonkokan Co., Ltd. (Reference) 3K061 AA24 AB01 AC03 BA05 BA10 DA01 DA12 DA18 EA01 EB08 EB18 NB01 NB02 NB05 3K065 AA24 AB01 AC03 BA05 BA10 CA01 3K070 DA06 DA16 DA27 DA37 DA45 DA49 4D002 AA19 AB01 FA02 DA01 DA02 DA12 DA16 DA02 DA12 DA12 DA12 DA12 DA16 AA37 AB03 AB07 BA05 BB03 CA15 CA29 CA34 CA40 CA45 CB02 CB09 CB32 CC06 CC12 DA03 DA20 4D021 FA22 GA05 GA08 GA11 HA10 4D054 AA02 EA02 EA10 EA22 EA23 4D058 JA04 RA19 SA20 TA01 UA03

Claims (7)

[Claims] 1. A hydrogen chloride removing agent blowing step of blowing a sodium hydrogen chloride removing agent into exhaust gas generated from a waste incinerator, a waste gasification melting furnace, or a waste incineration residue melting furnace, and a sodium hydrogen chloride removing step. Waste treatment exhaust gas and dust treatment characterized by including a dust collection process for collecting exhaust gas blown with agent and a classification process for classifying the collected dust to separate it into coarse particles and fine particles Method. 2. The particle size of the sodium-based hydrogen chloride removing agent blown in the hydrogen chloride removing agent blowing step is 10 μm to 30 μm.
2. The waste treatment exhaust gas and dust treatment method according to claim 1, which is a powder of a sodium-based hydrogen chloride removing agent having a diameter of .mu.m. 3. The method for treating waste gas and waste gas according to claim 1, wherein the sodium-based hydrogen chloride removing agent blown in the hydrogen chloride removing agent blowing step is in the form of an aqueous solution. 4. The waste treatment according to any one of claims 1 to 3, wherein the coarse particles separated in the classification step are sent to a stabilization treatment device to perform stabilization treatment of heavy metals. Exhaust gas and dust treatment method. 5. The method for treating waste gas and exhaust gas according to claim 1, wherein the coarse particles separated in the classification step are sent to a melting furnace for melting treatment. . 6. The method for treating waste gas and waste gas according to any one of claims 1 to 3, wherein the coarse particles separated in the classifying step are charged into a furnace as an exhaust gas source. . 7. A hydrogen chloride removing agent blowing device for blowing a sodium hydrogen chloride removing agent into exhaust gas generated from a waste incinerator, a waste gasification melting furnace, or a waste incineration residue melting furnace, and a sodium hydrogen chloride removing apparatus. A dust collector that collects the exhaust gas in which the agent has been blown, and a waste treatment exhaust gas and dust characterized by having a classification means that classifies the dust collected by the dust collector into coarse particles and fine particles. Processing equipment.