JP2022021636A - Fly ash treatment device and fly ash treatment method - Google Patents

Abstract

To provide a fly ash treatment device and a method for efficiently inhibiting the elution of heavy metals from the fly ash collected from exhaust in a waste incinerator.SOLUTION: A fly ash treatment device treats the fly ash collected from exhaust in a waste incinerator 1 and includes a reaction device 8 that receives the collected fly ash in a dry state and reacts it with carbon dioxide, and an exhaust cooling supply device for cooling the exhaust that has been collected after discharged from the waste incinerator to a temperature lower than 100°C for supply to the reaction device. The exhaust cooling supply device is a direct cooling device for bringing the collected exhaust into direct contact with a fluid for cooling or an indirect cooling device for indirectly cooling the collected exhaust.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fly ash treatment apparatus and a fly ash treatment method for suppressing the elution of heavy metals in the fly ash discharged from the waste incinerator and collected.

The exhaust gas discharged from the waste incinerator that incinerates the waste contains a large amount of soot dust (fly ash), and the fly ash is collected by a dust collector such as a bag filter, and the exhaust gas is removed. The collected fly ash contains heavy metals such as lead and cadmium, and when disposing of the land, the heavy metals are fixed and stabilized so that the elution amount of the heavy metals is below the regulation value. It is stipulated that heavy metals should be treated to suppress elution. Among the heavy metals contained in fly ash, the heavy metals to be treated are mainly lead because the content of lead is particularly high.

As a general stabilization treatment for heavy metals, a stabilizer is mixed with fly ash to fix and stabilize the heavy metals. However, since the stabilizer is expensive, there is a problem that the cost of stabilizing the fly ash increases.

In addition to the above-mentioned stabilization treatment, various measures for suppressing the elution of heavy metals have been studied. When an alkaline agent is supplied to the exhaust gas on the upstream side of a dust collector such as a bag filter to remove the acidic gas contained in the exhaust gas and the alkaline agent and the acidic gas are neutralized, the dust is collected by the bag filter. Since the flying ash contains an unreacted alkaline agent, it is strongly alkaline and is called "alkaline flying ash". The pH of alkaline fly ash is high, and heavy metals are easily eluted. For example, before or during the stabilization treatment of heavy metals with a stabilizer for the alkaline flying ash, carbon dioxide gas is supplied to carbonize the alkaline component in the flying ash to lower the pH of the alkaline flying ash. It has been studied to suppress the elution of heavy metals, reduce the amount of heavy metal stabilizer used, and reduce the cost of flying ash treatment.

Next, the carbonation treatment of fly ash will be described. The solubility of lead contained in fly ash varies greatly depending on the pH of the eluate, and since the eluate of alkaline fly ash has a high pH, lead is easily eluted. In the carbonation treatment, CaO and Ca (OH) ₂ , which are alkaline components in flying ash, are reacted with carbon dioxide gas to carbonate them into CaCO ₃ , which lowers the pH of the eluent and makes it difficult for lead to show poor solubility. It is a process to suppress the elution of lead as a soluble region. In the case of alkaline fly ash, slaked lime Ca (OH) ₂ which is blown for the purpose of removing acid gas and exists unreacted is the main alkaline component. In addition, lead contained in flying ash reacts with carbon dioxide gas to change the form of lead from easily soluble PbCl ₂ and PbO to poorly soluble PbCO ₃ , and lead carbonation reaction in which lead elution is suppressed is also carried out. Will be.

Patent Document 1 and Patent Document 2 disclose a reaction device and a method for performing carbonation treatment for fly ash stabilization treatment to reduce the cost of the fly ash stabilization treatment.

In Patent Document 1, water is supplied to alkaline fly ash containing heavy metals and kneaded so that water and alkaline fly ash are sufficiently mixed, and carbon dioxide gas is aerated through the alkaline fly ash kneaded with water. At that time, a heavy metal stabilizer is supplied and mixed before, during, or after the reaction between the alkaline fly ash and carbon dioxide gas to fix the heavy metals and perform an elution prevention treatment.

In Patent Document 2, water is added to alkaline fly ash and supplied to the reaction chamber as a wet ash state, and in the presence of water, fly ash and carbon dioxide gas are mixed in a heated atmosphere of 90 ° C. or lower, which can suppress the evaporation of water. React.

JP-A-2002-224640 Japanese Patent Application Laid-Open No. 2003-033748

However, in Patent Document 1 and Patent Document 2, when water is supplied to alkaline fly ash and then carbonation treatment is performed, the alkaline fly ash particles are bonded to each other by water and the contact between the alkaline fly ash particles and the carbon dioxide gas is poor. Therefore, there is a limit to improving the efficiency of the carbonation treatment.

In view of the above circumstances, the present invention can efficiently proceed with the carbonization treatment of fly ash in order to suppress the elution of heavy metals from the fly ash discharged from the waste incinerator and collected. An object of the present invention is to provide a treatment apparatus and a fly ash treatment method.

The above-mentioned problems are solved by the following fly ash treatment apparatus and fly ash treatment method based on the present invention.

[Fly ash processing equipment]
The fly ash treatment apparatus of the present invention is configured as the following first invention or second invention.

<First invention>
In a fly ash treatment device that treats fly ash collected from the exhaust gas of a waste incinerator
A reactor that accepts fly ash after dust collection in a dry state and reacts with carbon dioxide,
A fly ash treatment device including an exhaust gas temperature reducing supply device that cools the exhaust gas discharged from a waste incinerator and removed dust to less than 100 ° C. and supplies it to a reaction device.

In the first invention, the exhaust gas temperature reducing supply device is a direct temperature reducing device that directly contacts the exhaust gas after dust removal with a fluid for cooling, or an indirect temperature reducing device that indirectly reduces the temperature of the exhaust gas after dust removal. be able to. Further, the direct temperature reducing device can bring any one of cooling water, an alkaline aqueous solution, and air into contact as the heating fluid. Further, the indirect temperature reducing device includes a heat exchanger between the exhaust gas and the refrigerant, and cooling water or air can be used as the refrigerant.

<Second invention>
In a fly ash treatment device that treats fly ash collected from the exhaust gas of a waste incinerator
A reactor that accepts fly ash after dust collection in a dry state and reacts with carbon dioxide,
It is equipped with an exhaust gas temperature reduction / acid gas removal device that cools the exhaust gas discharged from the waste incinerator and removes dust to less than 100 ° C, and supplies acid gas to the reactor after removing the acid gas from the exhaust gas.
The exhaust gas heat reducing / acid gas removing device is a deheating cleaning device that sprays water or an alkaline aqueous solution on the dust-removed exhaust gas, an absorption device that brings an absorption liquid having a composition that absorbs acid gas into contact with the dust-removed exhaust gas, and the above. A flying ash treatment device characterized by being one of an acid gas dew condensation removing device that cools the exhaust gas after dust removal to a temperature below the dew point temperature of the acid gas and condenses the acid gas.

[Fly ash treatment method]
The fly ash treatment method of the present invention is configured as the following third invention or fourth invention.

<Third invention>
In the fly ash treatment method that treats the fly ash collected by removing the exhaust gas from the waste incinerator.
A reaction process in which fly ash after dust collection is received in a reaction device in a dry state and reacted with carbon dioxide,
A fly ash treatment method comprising a step of reducing the temperature of the exhaust gas after dust removal to less than 100 ° C. with a temperature reducing device and then supplying the exhaust gas to the reaction device.

In the third aspect of the invention, the exhaust gas temperature lowering step is a direct temperature lowering step in which the fluid for temperature reduction is in direct contact with the exhaust gas after dust removal, or an indirect reduction in temperature in which the exhaust gas after dust removal is indirectly contacted with the refrigerant. It can be a warm process. Further, in the direct temperature reducing step, any one of cooling water, an alkaline aqueous solution, and air can be brought into contact with the temperature reducing liquid. Further, in the indirect temperature reducing step, the exhaust gas can be heat-exchanged with the refrigerant, and cooling water or air can be used as the refrigerant.

<Fourth invention>
In the fly ash treatment method for treating fly ash collected from the exhaust gas of a waste incinerator
The fly ash after dust collection is received in a reaction device in a dry state and reacted with carbon dioxide.
By spraying water or an alkaline aqueous solution on the exhaust gas after dust removal with a low temperature cleaning device as an exhaust gas temperature reducing / acid gas removing device to reduce the temperature of the exhaust gas, and using an absorption device as an exhaust gas cooling / acid gas removing device. The absorption liquid having a composition that absorbs acid gas is brought into contact with the exhaust gas after dust removal, and the acid gas dew condensation removing device as an acid gas temperature reducing / acid gas removing device keeps the exhaust gas after dust removal below the dew point temperature of the acid gas. The temperature of the exhaust gas discharged from the waste incinerator and removed to be less than 100 ° C. is reduced to less than 100 ° C. and the acid gas is removed from the exhaust gas, and then the reaction device is used. A method for treating acid gas, which is characterized by supplying to.

According to the first invention and the third invention of the present invention described above, the fly ash discharged from the waste incinerator is received in the reaction device in a dry state, and the exhaust gas discharged from the waste incinerator and dedusted is discharged at 100 ° C. Since the temperature is reduced to less than the temperature and supplied, and the fly ash reacts with the carbon dioxide contained in the exhaust gas, it is possible to avoid the binding of the fly ash due to water, which causes a decrease in contact with the carbon dioxide, and the fly ash has high reaction efficiency. The carbonation treatment of ash can proceed.

Further, according to the second invention and the fourth invention, the temperature of the exhaust gas discharged from the waste incinerator and dust-removed is lowered to less than 100 ° C., and the acid gas is removed and supplied to the reactor. By providing a removal device and removing the acid gas contained in the exhaust gas, the acid gas condenses and condenses in the reaction device and the piping that introduces the exhaust gas to the reaction device, and acid liquid is generated, causing corrosion of the device and piping. It can be prevented, and it is also possible to prevent the occurrence of defects due to corrosion damage.

It is a figure which shows an example of the outline structure of the waste incinerator which concerns on 1st Embodiment of this invention. It is a figure which shows the other example of the outline structure of the waste incinerator which concerns on 1st Embodiment of this invention. It is a figure which shows an example of the outline structure of the waste incinerator which concerns on the 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but prior to that, the principles of the invention will be described.

<< Principle of invention >>
<Criteria for the pH of fly ash and the amount of lead elution>

The standard value for the elution amount of lead in fly ash is that the elution amount of lead is 0.3 mg / 1 when it is disposed of in land, and the elution amount of lead is 0.01 mg / 1 when it is effectively used as a resource. For this reason, when fly ash is to be disposed of in landfills or effectively used as a resource, it is necessary to carry out treatment to make the fly ash have properties equal to or less than the above standard value.

Among the heavy metals in fly ash, lead, which has a particularly high content, is an amphoteric metal, and in the region where the pH is lower than 12, the solubility is significantly reduced and it becomes difficult to elute, so the reaction between fly ash and carbonic acid. By lowering the pH of fly ash to 12 or less by the carbonation treatment with the above, the amount of lead elution can be extremely reduced. In addition, the reaction in which heavy metals such as lead are carbonated to become non-eluting substances also proceeds, and the elution of heavy metals is suppressed.

<Procedure for fly ash treatment>
In this embodiment, the exhaust gas discharged from the waste incinerator to the fly ash before the stabilization treatment in which the fly ash is mixed with a stabilizer to fix and stabilize the heavy metal to make the fly ash have properties below the standard value. By reacting the alkaline components such as Ca (OH) ₂ and CaO contained in the fly ash with carbon dioxide in the exhaust gas to form carbonic acid chloride, the pH of the fly ash is lowered and the elution of heavy metals is suppressed. At the same time, the lead in fly ash is reacted with carbon dioxide in the exhaust gas to form a carbonate, which is non-eluting. By performing the treatment of lowering the pH of fly ash to suppress the elution of heavy metals and the treatment of producing lead carbonate to make it non-eluting in this way, a stabilizer for fixing and stabilizing heavy metals It is possible to reduce the amount of carbonic acid used and the cost of fly ash treatment.

In addition, the fly ash discharged from the waste incinerator is received in the reactor in a dry state, the exhaust gas discharged from the waste incinerator and dust-removed is supplied to the reactor, and the fly ash is combined with the carbon dioxide contained in the exhaust gas. Since the reaction is carried out, it is possible to avoid the binding of fly ash particles by water, which is a factor of lowering the contact efficiency with carbon dioxide, and it is possible to proceed with the carbonization treatment of fly ash with high reaction efficiency.

<Exhaust gas temperature and reaction efficiency>
The relationship between the exhaust gas temperature and the reaction efficiency when reacting fly ash with carbon dioxide contained in the exhaust gas was investigated.

The reaction device is filled with fly ash discharged from the municipal waste incinerator and collected by the bag filter, and the exhaust gas discharged from the bag filter is cooled (cooled) to various temperatures by the temperature reducing device. A ventilation test was performed. The pH of the fly ash eluate tested was 12.6. The composition of the aerated exhaust gas was 10 to 15 vol% for carbon dioxide and 10 to 20 vol% for water.

Table 1 shows the pH of the fly ash eluate after aeration of exhaust gas at various temperatures. When the exhaust gas temperature is less than 100 ° C, the pH becomes 12.0 or less, when the exhaust gas temperature is 60 ° C or less, the pH becomes 11.0 or less, and the lower the temperature, the lower the pH and the carbonation reaction is promoted. It was found that the reaction efficiency was high. The exhaust gas is cooled (cooled) to less than 100 ° C and supplied, more preferably 60 ° C or lower (cooled) and supplied, and the carbon dioxide contained in the exhaust gas is reacted with fly ash to cause fly ash. Since it is possible to promote the progress of the carbonation reaction of fly ash, it is possible to proceed with the carbonation treatment of fly ash with high reaction efficiency. Further, the lower limit of the exhaust gas temperature is preferably set to room temperature (generally 20 ° C.) or higher in consideration of the temperature of the fluid (water, air, etc.) that reduces the temperature of the exhaust gas.

FIG. 1 shows an example relating to an outline configuration of a waste incinerator having a fly ash treatment apparatus as the first embodiment of the present invention.

The waste incineration facility shown in FIG. 1 is a collection of a waste incinerator 1, a boiler 2 that recovers the waste heat of the exhaust gas from the waste incineration furnace 1, a bag filter that removes the exhaust gas after the waste heat recovery, and the like. The dust device 3, the alkaline agent supply device 4 that supplies the alkaline agent to the combustion exhaust gas flowing through the chimney A on the upstream side of the dust collector 3, and a part of the exhaust gas discharged from the dust collector 3 are cooled and described later. It is provided with a temperature reducing device 5 as an exhaust gas temperature reducing supply device for supplying the exhaust gas, a blower 6 for sending the exhaust gas to the downstream side, a chimney 7, and a reaction device 8 for flying ash.

The boiler 2, the dust collector 3, and the blower 6 are sequentially arranged in the flue A connecting the waste incinerator 1 and the chimney 7 from the upstream side to the downstream side along the flow of exhaust gas. The alkaline agent supply device 4 is connected to the flue A so as to supply the alkaline agent to the combustion exhaust gas in the flue A. Further, the temperature reducing device 5 is connected to a branch pipe B branched from the flue A on the downstream side of the dust collector 3, and receives a part of the exhaust gas in the flue A from the branch pipe B to reduce the temperature. It is designed to warm up. The branch pipe B further connects the outlet side of the temperature reducing device 5 to the reaction device 8, and supplies the reduced temperature exhaust gas to the reaction device 8. The reaction device 8 is also connected to the dust collector 3 and receives fly ash from the dust collector 3. Further, the reaction device 8 is connected to the flue A at a position between the boiler 2 and the dust collector 3, so that the exhaust gas discharged from the reaction device 8 is returned to the flue A.

Next, the alkaline agent supply device 4, the temperature reducing device 5, and the reaction device 8 will be described in more detail.

<Alkaline agent supply device>
The alkaline agent supply device 4 supplies an alkaline agent (for example, slaked lime) to the exhaust gas discharged from the boiler 2 and reacts the acid gas in the exhaust gas with the alkaline agent to generate a reaction product and remove the acidic gas. Then, the reaction product and the unreacted alkaline agent are collected together with the soot by the dust collector 3. Here, the fly ash collected by the dust collector 3 contains an unreacted alkaline agent, and the pH of the eluate is high.

<Temperature reducing device>
The type of the temperature reducing device 5 is not limited, and the exhaust gas is heated to a predetermined temperature of less than 100 ° C. by directly spraying water (cooling water) or an alkaline aqueous solution as a fluid for cooling the exhaust gas, or blowing air into the exhaust gas. , More preferably, it is formed as a direct temperature reducing device that reduces (cools) the temperature to a predetermined temperature of 60 ° C. or lower.

<Reactor>
The reaction device 8 receives the fly ash in a dry state, and introduces a part of the exhaust gas discharged from the dust collector 3 and deheated by the temperature reducing device 5 to combine the fly ash and carbon dioxide in the exhaust gas. It is configured to contact and react. In order to carry out the reaction effectively, for example, a fixed layer or a moving layer of fly ash is formed in the reaction device 8. Thus, the fly ash reacts with carbon dioxide in the exhaust gas in the reaction device 8, is carbonated, and is discharged as the treated fly ash. The treated fly ash is mixed with a heavy metal stabilizer to fix and stabilize the heavy metal so that the fly ash has properties equal to or less than the standard value.

The reaction device 8 is provided with a fly ash receiving means and a fly ash discharging means for accumulating fly ash in the reaction device 8 to form a fixed layer or for forming a moving layer (both are shown in the figure). figure). Further, a means for introducing the exhaust gas and dispersing it in the fly ash for ventilating a part of the exhaust gas of the waste incinerator 1 to the fly ash in the reaction device 8 is also connected via the branch pipe B. (Not shown). Therefore, for example, a gas distribution tube (not shown) is provided in the reaction device 8. The gas distribution pipe is formed in a grid pattern or by arranging a large number of pipes in parallel. Further, a stirring means (not shown) for stirring the fly ash in the reaction device 8 to promote contact with the exhaust gas may be provided.

When a part of the exhaust gas of the waste incinerator is introduced from the temperature reducing device 5 to the reaction device 8 via the branch pipe B, a part of the exhaust gas is introduced from the temperature reducing device 5 to a predetermined temperature of less than 100 ° C. The temperature is preferably reduced (cooled) to a predetermined temperature of 60 ° C. or lower. For this reason, the temperature reducing device 5 uses a direct temperature reducing device that directly contacts the temperature reducing fluid with the exhaust gas, and uses any one of cooling water, an alkaline aqueous solution, and air as the temperature reducing device. The exhaust gas to be brought into contact is introduced into the reactor 8 after being cooled (cooled) to a predetermined temperature. The temperature reducing device includes a heat exchanger and other heat reducing means for indirectly contacting the exhaust gas with the heat exchange refrigerant (fluid for heating) instead of the temperature reducing device 5 of the direct temperature reducing device type. An indirect heat reducing device may be used. When a heat exchanger is used as the indirect heat reducing device, for example, cooling water or air may be used as the heat exchange refrigerant.

Thus, the fly ash collected by the dust collector 3 is supplied to the reaction device 8 in a dry state to form a fixed layer, or a predetermined amount is received and extracted to form a moving layer. Moisture is not separately supplied to the fly ash, and the fly ash is left in a dry state, and carbon dioxide and water vapor contained in the exhaust gas introduced into the reaction device 8 are brought into good contact with the surface of the fly ash particles to carbonize the fly ash. Proceed with the chemical reaction. Since the fly ash particles are not bonded to each other by water, the contact efficiency with carbon dioxide on the surface of the fly ash particles is high, and the carbonation reaction proceeds efficiently.

Next, the operation procedure of the waste incinerator in the present embodiment configured as described above will be described.

<Operation procedure>
First, the waste is supplied to the waste incinerator 1 and burned, and the combustion exhaust gas is introduced into the boiler 2 to recover heat. Next, the exhaust gas was sprayed with water by a temperature reducing tower (not shown) provided between the boiler 2 and the alkaline agent supply device 4 as needed, and rapidly cooled to about 150 ° C to 200 ° C. After that, the alkaline agent is supplied by the alkaline agent supply device 4 and sent to a dust collector 3 such as a bug filter for dust removal treatment. A part of the exhaust gas removed from the dust is cooled by the temperature reducing device 5 through the branch pipe B and then supplied to the reaction device 8, and the rest of the exhaust gas is sent to the chimney 7 by the blower 6 and discharged to the atmosphere.

The fly ash containing the unreacted alkaline agent collected by the dust collector 3 is sent to the reaction device 8 in a dry state, forms a fly ash layer in the reaction device 8, and is discarded in the fly ash layer. The exhaust gas from the incinerator 1 is ventilated. In the present embodiment, as described above, a part of the exhaust gas discharged from the dust collector 3 is taken into the temperature reducing device 5 by the exhaust gas supply blower (not shown), and reaches a predetermined temperature within the range of less than 100 ° C. After the temperature is reduced (cooled) by contacting with the temperature-reducing fluid, the reduced-temperature (cooled) exhaust gas is introduced into the reaction device 8 as exhaust gas to be aerated in the fly ash layer. The exhaust gas that has passed through the fly ash layer is returned to the flue A on the upstream side of the dust collector 3.

The fly ash staying in the reaction apparatus 8 is configured to form a moving layer and is sequentially extracted, so that the residence time of the fly ash in the reaction apparatus 8 is maintained at a predetermined time. , The extraction amount is adjusted as appropriate. Further, a batch processing method may be used in which fly ash is retained in the reaction apparatus 8 for a predetermined time to form a fixed layer and discharged after the reaction is completed. The residence time is set so that the carbon dioxide in the exhaust gas from the waste incinerator 1 comes into contact with the surface of the fly ash particles and the reaction proceeds sufficiently.

By aerating the exhaust gas discharged from the waste incinerator 1 through the fly ash in the reaction device 8, the carbon dioxide in the exhaust gas is reacted with the alkaline components such as Ca (OH) ₂ and CaO contained in the fly ash. It is carbonated and chlorideed to lower the pH of fly ash and suppress the elution of heavy metals. Further, a treatment is performed in which lead in fly ash is reacted with carbon dioxide in the exhaust gas to form a carbonate and non-eluting.

Further, a heavy metal stabilizer is mixed with the treated fly ash discharged from the reaction apparatus 8 after carbonation treatment, and the heavy metal is fixed and stabilized to make the fly ash have properties equal to or less than the reference value. By performing the treatment of lowering the pH of fly ash to suppress the elution of heavy metals and the treatment of producing lead carbonate to make it non-eluting in this way, a stabilizer for fixing and stabilizing heavy metals It is possible to reduce the amount of carbonic acid used and the cost of fly ash treatment.

A control device is provided to control the reaction device 8, and the temperature of the exhaust gas supplied to the reaction device 8, the amount of the exhaust gas supplied, and the reaction device 8 based on the pH measurement value of the fly ash processed by this control device. One or more of the residence time in the reaction device 8 and the extraction rate of the incineration ash from the reaction device 8 may be adjusted.

As the first embodiment, as a modification of the example of FIG. 1, the configuration as shown in FIG. 2 may be used.

In the case of the modification shown in FIG. 2, instead of the temperature reducing device 5 of FIG. 1, the exhaust gas is directly reduced to the flue A connecting the dust collector 3 such as a bag filter and the blower 6. A wet smoke washing device 9 that is a heating device and sprays water or an alkaline aqueous solution is provided, and all exhaust gas passing through the flue A is treated by the wet smoke washing device 9. Further, the flue A connecting the wet smoke washing device 9 and the blower 6 is provided with a heating device 10 for reheating the exhaust gas. Other than these points, it is the same as in FIG.

In the modification shown in FIG. 2, the exhaust gas obtained by removing the acidic gas by supplying the alkaline agent by the alkaline agent supply device 4 and collecting the reaction product by the dust collecting device 3 is introduced into the wet smoke washing device 9. , The exhaust gas is brought into contact with water or an alkaline aqueous solution (washing water) to remove the remaining acidic gas.

Further, the wet smoke washing device 9 removes the acid gas remaining in the exhaust gas and lowers the exhaust gas temperature to less than 100 ° C.

A part of the exhaust gas discharged from the wet smoke washing device 9 is supplied to the reaction device 8, and the rest is reheated by the heating device 10 until the temperature reaches the acid dew point or higher, and then discharged from the chimney 7 to the atmosphere.

By lowering the exhaust gas temperature with the wet smoke washing device 9 and removing the acid gas remaining in the exhaust gas, the exhaust gas having a suitable temperature is supplied to the reaction device 8 and the exhaust gas is introduced into the reaction device 8 and the reaction device 8. It is possible to prevent acid gas from condensing and condensing in the branch pipe B to generate an acidic liquid and causing corrosion to the device and the pipe, and it is possible to prevent the occurrence of defects due to corrosion damage.

Next, the second embodiment of the present invention is shown in FIG.

In this second embodiment, the exhaust gas temperature reducing / acid gas removing device 11 is arranged in the branch pipe B instead of the temperature reducing device 5 in the first embodiment of FIG. 1, and the others are shown in FIG. It is the same as the embodiment.

A part of the exhaust gas discharged from the waste incinerator 1 and removed from dust is cooled (cooled) to less than 100 ° C. by the exhaust gas temperature reducing / acid gas removing device 11 via the branch pipe B, and the acid gas is removed. Is supplied to the reactor 8. In this exhaust gas temperature reducing / acid gas removing device 11, carbonation is efficiently promoted by lowering the exhaust gas temperature, so that the amount of stabilizer used for fixing / stabilizing heavy metals can be reduced, and fly ash can be used. Processing costs can be reduced. Further, by removing the acidic gas contained in the exhaust gas, the acidic gas (for example, sulfite gas) is condensed and condensed in the branch pipe B for introducing the exhaust gas into the reaction device 8 and the reaction device 8, and an acidic liquid (for example, sulfuric acid) is generated. It is possible to prevent the equipment and piping from being corroded, and it is possible to prevent the occurrence of defects due to corrosion damage.

As the exhaust gas temperature reducing / acid gas removing device, any of the following devices can be used.
-A low-temperature cleaning device that sprays water or an alkaline aqueous solution onto the exhaust gas to dissolve the acid gas in the exhaust gas in water, or neutralizes and removes the acid gas from the alkaline aqueous solution.
-An absorption device that removes acid gas from the exhaust gas by contacting the absorption liquid with a composition that absorbs the acid gas in the exhaust gas with the exhaust gas and ventilating the exhaust gas into the absorption liquid, or by spraying the absorption liquid on the exhaust gas.
-An acid gas dew point removing device that cools the exhaust gas below the dew point temperature of the acid gas by a heat exchanger or a cooling device and condenses the acid gas.

1 Waste incinerator 5 Heat reduction device (exhaust gas temperature reduction supply device)
8 Reaction device 9 Wet smoke washing device (exhaust gas temperature reduction supply device)
11 Exhaust gas temperature reduction / acid gas removal device

Claims (10)

In a fly ash treatment device that treats fly ash collected from the exhaust gas of a waste incinerator
A reactor that accepts fly ash after dust collection in a dry state and reacts with carbon dioxide,
A fly ash treatment device including an exhaust gas temperature reducing supply device that cools the exhaust gas discharged from a waste incinerator and removed dust to less than 100 ° C. and supplies it to a reaction device. A claim that the exhaust gas temperature reducing supply device is a direct temperature reducing device in which a fluid for heat reducing is directly brought into contact with the exhaust gas after dust removal, or an indirect temperature reducing device for indirectly reducing the temperature of the exhaust gas after dust removal. The fly ash processing apparatus according to 1. The fly ash treatment device according to claim 2, wherein the direct temperature reducing device is brought into contact with any one of cooling water, an alkaline aqueous solution, and air as a fluid for cooling. The flying ash treatment device according to claim 2, wherein the indirect temperature reducing device includes a heat exchanger between the exhaust gas and the refrigerant, and uses cooling water or air as the refrigerant. In a fly ash treatment device that treats fly ash collected from the exhaust gas of a waste incinerator
A reactor that accepts fly ash after dust collection in a dry state and reacts with carbon dioxide,
It is equipped with an exhaust gas temperature reduction / acid gas removal device that cools the exhaust gas discharged from the waste incinerator and removes dust to less than 100 ° C, and supplies acid gas to the reactor after removing the acid gas from the exhaust gas.
The exhaust gas heat reducing / acid gas removing device is a deheating cleaning device that sprays water or an alkaline aqueous solution on the dust-removed exhaust gas, an absorption device that brings an absorption liquid having a composition that absorbs acid gas into contact with the dust-removed exhaust gas, and the above. A flying ash treatment device characterized by being one of an acid gas dew condensation removing device that cools the exhaust gas after dust removal to a temperature below the dew point temperature of the acid gas and condenses the acid gas. In the fly ash treatment method that treats the fly ash collected by removing the exhaust gas from the waste incinerator.
A reaction process in which fly ash after dust collection is received in a reaction device in a dry state and reacted with carbon dioxide,
A fly ash treatment method comprising a step of reducing the temperature of the exhaust gas after dust removal to less than 100 ° C. with a temperature reducing device and then supplying the exhaust gas to the reaction device. The exhaust gas temperature reduction step is a direct temperature reduction step in which the fluid for temperature reduction is in direct contact with the exhaust gas after dust removal, or an indirect temperature reduction step in which the exhaust gas after dust removal is indirectly contacted with the refrigerant to reduce the temperature. The fly ash treatment method according to claim 6. The fly ash treatment method according to claim 7, wherein in the direct temperature reducing step, any one of cooling water, an alkaline aqueous solution, and air is brought into contact with the liquid for cooling. The fly ash treatment method according to claim 7, wherein in the indirect temperature reducing step, the exhaust gas is heat-exchanged with the refrigerant and cooling water or air is used as the refrigerant. In the fly ash treatment method for treating fly ash collected from the exhaust gas of a waste incinerator
The fly ash after dust collection is received in a reaction device in a dry state and reacted with carbon dioxide.
By spraying water or an alkaline aqueous solution on the exhaust gas after dust removal with a low temperature cleaning device as an exhaust gas temperature reducing / acid gas removing device to reduce the temperature of the exhaust gas, and using an absorption device as an exhaust gas cooling / acid gas removing device. The absorption liquid having a composition that absorbs acid gas is brought into contact with the exhaust gas after dust removal, and the acid gas dew condensation removing device as an acid gas temperature reducing / acid gas removing device keeps the exhaust gas after dust removal below the dew point temperature of the acid gas. The temperature of the exhaust gas discharged from the waste incinerator and removed to be less than 100 ° C. is reduced to less than 100 ° C. and the acid gas is removed from the exhaust gas, and then the reaction device is used. A method for treating acid gas, which is characterized by supplying to.

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