JP2020192522A - Incinerated ash processing device and incinerated ash processing method - Google Patents

Abstract

To provide an incinerated ash processing device which enables reduction of a moisture percentage of incinerated ash and enables a process for making heavy metals into a poorly-soluble state to be performed efficiently.SOLUTION: An incinerated ash processing device includes: an ash transport device 12 which transports incinerated ash; a water jet nozzle 13 which adds water to the incinerated ash transported by the ash transport device 12; and a suction pipe 15 which adds an incineration exhaust gas including CO2 to the incineration ash to which the water is added by the water jet nozzle 13.SELECTED DRAWING: Figure 1

Description

The present invention relates to an incineration ash treatment apparatus for treating incineration ash so as to suppress elution of heavy metals, and an incineration ash treatment method.

For example, municipal waste and industrial waste are incinerated in incinerators for the purpose of volume reduction, detoxification, and recycling. The incineration ash generated by the incineration process is extinguished and cooled, then taken out of the site and processed by landfill disposal or recycling.

Incineration ash contains harmful substances, especially heavy metals. Therefore, if the amount of heavy metals eluted from the incineration ash exceeds the standard value, it cannot be disposed of in landfill or used as a resource. In order to deal with such a situation, for example, heavy metals must be stabilized before landfill disposal, and a sparing treatment must be performed so that the elution amount becomes equal to or less than the standard value.

Conventionally, there is a method as disclosed in Patent Document 1, for example, as a treatment for making heavy metals sparingly soluble. In this method, the incineration ash discharged from the incinerator is stacked and stored in the treatment yard, water is sprayed on the incineration ash, and CO ₂ such as air and incineration exhaust gas is contained in the incineration ash layer by a gas blowing nozzle. I try to blow in the contained gas. As a result, CO ₂ is reacted with the heavy metals contained in the incineration ash to chlorinate the heavy metals, making the heavy metals sparingly soluble, and by setting the pH of the incineration ash to the sparingly soluble region, the heavy metals from the incineration ash. Elution of carbon dioxide can be suppressed.

In the method according to Patent Document 1 described above, the CO _2- containing gas is aerated through the relatively dense wet incineration ash laminated in the treatment yard. For this reason, there is a problem that the CO _2- containing gas cannot be sufficiently brought into contact with the incineration ash, and the efficiency of the sparing treatment of heavy metals is poor. Further, in the method according to Patent Document 1 described above, it is necessary to provide a processing yard for storing incineration ash, which causes a problem that the scale of the facility becomes large. Further, the method according to Patent Document 1 described above requires a separate wastewater treatment facility for treating an excessive amount of leachate generated by sprinkling water in the treatment yard, which causes a problem that the facility cost increases.

As a device that can solve the above problems, for example, there is an incineration ash detoxification treatment apparatus disclosed in Patent Document 2. This incineration ash detoxification treatment device is provided with a storage water tank for storing incineration ash and water discharged from the incinerator, and is configured to blow exhaust gas containing CO ₂ from the incinerator into the storage water tank.

Japanese Unexamined Patent Publication No. 2004-74100 JP-A-2015-196128

In the incineration ash detoxification treatment apparatus according to Patent Document 2, when the exhaust gas containing CO ₂ from the incinerator is blown into the storage water tank, the incineration ash immersed in the storage water tank is in the form of bubbles in the storage water. It reacts with CO ₂ and CO ₂ dissolved water, and carbon dioxide reaction of, for example, lead contained in incineration ash is carried out. Since this carbonation reaction is carried out in a state where the incineration ash is immersed in the stored water and comes into contact with the stored water with a sufficient area, it is possible to efficiently perform the sparing treatment of heavy metals such as lead.

However, in the incineration ash detoxification treatment apparatus according to Patent Document 2, the incineration ash is completely submerged and then exposed from the water surface to drain the water. Therefore, the water content of the incineration ash is affected by the draining time and the like. Therefore, it is difficult to suppress the water content within a predetermined range. Since the treatment cost of incineration ash is settled by weight, the treatment cost becomes high when the water content of the incineration ash is high.

The present invention has been made in view of the above problems, and is an incineration ash treatment apparatus capable of suppressing the water content of incineration ash and efficiently performing a sparing treatment of heavy metals, and an incineration ash. The purpose is to provide a processing method.

The characteristic configuration of the incineration ash treatment apparatus according to the present invention for solving the above problems is
Incineration ash transport means for transporting incineration ash and
A water addition means for adding water to the incineration ash transported by the incineration ash transport means,
A neutralizing means for adding a neutralizing gas containing CO ₂ to the incineration ash to which water has been added by the water adding means, and a neutralizing means.
To prepare for.

In the incineration ash treatment apparatus of this configuration, water is added by the water addition means to the incineration ash transported by the incineration ash transport means. As a result, the water content of the incinerated ash can be suppressed as compared with that of Patent Document 2 in which the incinerated ash is completely submerged. Further, in the incineration ash treatment apparatus having this configuration, a neutralizing gas containing CO ₂ is added to the incineration ash to which water has been added by a neutralizing means. As a result, the reaction between the hydroxide in the incineration ash and CO ₂ and the reaction between the heavy metals in the incineration ash and CO ₂ proceed efficiently, respectively, and the heavy metals are efficiently made sparingly soluble. be able to.

In the incineration ash treatment apparatus according to the present invention
The neutralizing means is preferably a blow pipe into which the neutralizing gas is blown.

According to the incineration ash treatment device of this configuration, since the neutralizing means is a blowing pipe for blowing the neutralizing gas, the neutralizing gas enters deeper into the incineration ash, and CO ₂ contained in the neutralizing gas. Can be reliably brought into contact with hydroxides and heavy metals in the incineration ash, and the sparing treatment of heavy metals can be performed more efficiently.

In the incineration ash treatment apparatus according to the present invention
It is preferable to provide a casing capable of containing the incineration ash to which the neutralizing gas is added.

According to the incineration ash treatment apparatus of this configuration, since the incineration ash to which the neutralizing gas is added is provided with a casing capable of accommodating the incineration ash, the emission of the neutralizing gas added to the incineration ash to the outside can be suppressed by the casing. Therefore, the neutralizing gas can be efficiently brought into contact with the incineration ash.

In the incineration ash treatment apparatus according to the present invention
It is preferable to provide a reflux means for refluxing the unreacted neutralizing gas to the neutralizing means.

According to the incineration ash treatment apparatus having this configuration, since the recirculation means for returning the unreacted neutralizing gas to the neutralizing means is provided, CO ₂ contained in the neutralizing gas can be treated to make heavy metals sparingly soluble. It can be used without waste.

In the incineration ash treatment apparatus according to the present invention
It is preferable to provide a recirculation amount control means for controlling the recirculation amount by the recirculation means based on the CO ₂ concentration in the neutralizing gas.

According to the incineration ash treatment apparatus having this configuration, since the recirculation amount control means for controlling the recirculation amount by the recirculation means based on the CO ₂ concentration in the neutralizing gas is provided, for example, the CO ₂ concentration in the neutralizing gas can be adjusted. When the value is lower than the lower limit of the predetermined range, the amount of recirculation is reduced, and when the CO ₂ concentration in the neutralizing gas is higher than the upper limit of the predetermined range, the amount of recirculation is increased. It will be possible. As a result, the CO ₂ concentration in the neutralizing gas is maintained within a predetermined range, and the CO ₂ contained in the neutralizing gas is hardly soluble in heavy metals while stably performing the sparing treatment of heavy metals. It can be used without waste for the conversion process.

In the incineration ash treatment apparatus according to the present invention
The heavy metal elution prevention agent is directly added to the incineration ash transported by the incineration ash transport means, or the heavy metal elution prevention agent is added by the water addition means. It is preferable that the heavy metal elution preventive agent adheres to the incineration ash by mixing with water.

According to ash processing apparatus of this configuration, in addition to adding to the ash of the CO ₂ containing neutralizing gas, since incineration ash to heavy metals stabilization agent is affixed, heavy metals by CO ₂ containing neutralizing gas Due to the synergistic effect of the poor solubility treatment of the above and the stabilization treatment of heavy metals with a heavy metal stabilizing agent, the elution of heavy metals from the incineration ash can be prevented more reliably.

In the incineration ash treatment apparatus according to the present invention
A heavy metal content measuring means for measuring the content of heavy metals contained in the incineration ash transported by the incineration ash transporting means, and a heavy metal content measuring means.
A chemical addition means for adding a heavy metal elution prevention agent to the incineration ash transported by the incineration ash transport means to prevent the elution of heavy metals.
A drug addition amount control means for controlling the addition amount of the heavy metal elution prevention drug added by the drug addition means is provided.
The chemical addition amount control means includes the content of heavy metals contained in the incineration ash and the heavy metals when water is added to the incineration ash by the water addition means and the neutralizing gas is added by the neutralization means. The elution amount of heavy metals is calculated from the content of heavy metals measured by the heavy metals content measuring means based on the relationship data with the elution amount of the heavy metals, and the calculated elution amount of the heavy metals is the elution reference value. If it exceeds, the amount of the heavy metal elution prevention agent added required to bring the amount of heavy metals elution to the elution reference value or less is calculated, and the amount added by the agent addition means is calculated. It is preferable to control the amount of the heavy metal elution prevention agent added.

In the incineration ash treatment apparatus of this configuration, the content of heavy metals contained in the incineration ash and the heavy metals when water is added to the incineration ash by the water addition means and the neutralizing gas is added by the neutralization means. The elution amount of heavy metals is calculated from the content of heavy metals measured by the heavy metal content measuring means based on the relational data with the elution amount of the kind. When the calculated elution amount of heavy metals exceeds the elution reference value, the amount of heavy metals elution prevention agent added required to bring the elution amount of heavy metals to the elution standard value or less is calculated. Then, the addition amount of the heavy metal elution prevention agent added by the agent addition means is controlled so as to be the calculated addition amount. Therefore, depending on the fluctuation of the content of heavy metals contained in the incineration ash, even if the elution amount of heavy metals may exceed the elution standard value even by the sparing treatment by adding water and neutralizing gas. The elution amount of heavy metals can be suppressed to the elution standard value or less.

Next, the characteristic configuration of the incineration ash treatment method according to the present invention for solving the above problems is as follows.
The incineration ash transport process for transporting incineration ash and
A water addition step of adding water to the incineration ash transported by the incineration ash transfer step, and a water addition step.
A neutralization step of adding a neutralizing gas containing CO ₂ to the incineration ash to which water was added by the water addition step, and a neutralization step.
To include.

In the incineration ash treatment method of this configuration, water is added by the water addition step to the incineration ash transported by the incineration ash transport step. As a result, the water content of the incinerated ash can be suppressed as compared with that of Patent Document 2 in which the incinerated ash is completely submerged. Further, in the incineration ash treatment method having this configuration, a neutralizing gas containing CO ₂ is added to the incineration ash to which water has been added by a neutralization step. As a result, the reaction between the hydroxide in the incineration ash and CO ₂ and the reaction between the heavy metals in the incineration ash and CO ₂ proceed efficiently, respectively, and the heavy metals are efficiently made sparingly soluble. be able to.

In the incineration ash treatment method according to the present invention
A heavy metal content measuring step for measuring the content of heavy metals contained in the incineration ash transported by the incineration ash transport step, and a heavy metal content measuring step.
Relationship data between the content of heavy metals contained in the incineration ash and the elution amount of heavy metals when water is added to the incineration ash by the water addition step and the neutralizing gas is added by the neutralization step. Based on the above, a heavy metal elution amount calculation step of calculating the elution amount of heavy metals from the heavy metal content measured by the heavy metal content measurement step,
When the elution amount of heavy metals calculated in the heavy metal elution amount calculation step exceeds the elution standard value, the amount of the heavy metal elution prevention agent added to keep the elution amount of heavy metals below the elution standard value is calculated. Chemical addition amount calculation process and
A chemical addition amount control step for controlling the addition amount of the heavy metal elution prevention chemical to the incineration ash transported by the incineration ash transport step so that the addition amount is calculated in the chemical addition amount calculation step.
It is preferable to further include.

In the incineration ash treatment method of this configuration, the content of heavy metals contained in the incineration ash and the heavy metals when water is added to the incineration ash by the water addition step and the neutralizing gas is added by the neutralization step. Based on the relationship data with the elution amount of the heavy metals, the heavy metal elution amount calculation step of calculating the elution amount of heavy metals from the content of heavy metals measured by the heavy metal content measurement step is carried out. When the elution amount of heavy metals calculated in the heavy metal elution amount calculation step exceeds the elution standard value, the addition amount of the heavy metal elution prevention agent required to keep the elution amount of heavy metals below the elution standard value is calculated. The chemical addition amount calculation step is carried out. Then, a chemical addition amount control step for controlling the addition amount of the heavy metal elution prevention chemical to the incineration ash transported by the incineration ash transport step is carried out so that the addition amount is calculated in the chemical addition amount calculation step. .. Therefore, depending on the fluctuation of the content of heavy metals contained in the incineration ash, even if the elution amount of heavy metals may exceed the elution standard value even by the sparing treatment by adding water and neutralizing gas. The elution amount of heavy metals can be suppressed to the elution standard value or less.

FIG. 1 is a block diagram showing a schematic system of an incineration ash treatment apparatus according to the first embodiment of the present invention. FIG. 2 is a block diagram showing a schematic system of an incineration ash treatment apparatus according to a second embodiment of the present invention. FIG. 3 is a block diagram showing a schematic system of an incineration ash treatment apparatus according to a third embodiment of the present invention. FIG. 4 is a flowchart showing a procedure for treating incineration ash by the incineration ash treatment apparatus according to the third embodiment of the present invention.

Hereinafter, the present invention will be described with reference to FIGS. 1 to 4. However, the present invention is not intended to be limited to the configurations described in the embodiments and drawings described below.

[First Embodiment]
FIG. 1 shows a block diagram showing a schematic system of an incineration ash treatment apparatus according to a first embodiment of the present invention.

<Overall configuration>
In FIG. 1, the incinerator 1 incinerates, for example, municipal waste, industrial waste, and the like. A boiler 2, an economizer 3, a temperature reducing tower 4, a bug filter 5, an attracting blower 6, and a chimney 7 are arranged in this order on the downstream side of the incineration exhaust gas flow of the incinerator 1. The incinerated exhaust gas generated by the incineration process in the incinerator 1 is sequentially sent to the boiler 2, the economizer 3, the temperature reducing tower 4, and the bug filter 5 by the attracting action of the attracting blower 6.

The boiler 2 uses the heat of the incineration exhaust gas to generate steam, and the economizer 3 uses the residual heat of the incineration exhaust gas to heat the water supplied to the boiler 2. In the temperature reducing tower 4, the incinerated exhaust gas from the economizer 3 is cooled to a predetermined temperature. The bug filter 5 removes dust and the like contained in the incinerated exhaust gas after cooling. Then, the incinerated exhaust gas after the dust and the like are removed is discharged to the outside through the chimney 7 by the attracting blower 6. The incinerated exhaust gas after dust is removed by the bug filter 5 contains 5 to 20% by volume of CO ₂ (temperature: 80 to 160 ° C.).

The incineration ash treatment device 10A shown in FIG. 1 is a device for performing a sparing treatment so as to suppress elution of heavy metals contained in the incineration ash generated by the incineration in the incinerator 1. The incineration ash treatment device 10A mainly includes an ash discharge device 11 as an incineration ash discharge means, an ash transfer device 12 as an incineration ash transfer means, a water injection nozzle 13 as a water addition means, and a moisture meter 14 as a moisture content measuring means. , A blow pipe 15 as a neutralizing means, and a control device 16 as a control means.

<Ash discharge device>
The ash discharge device 11 temporarily stores the incineration ash discharged from the incinerator 1 and discharges it as needed. Examples of the ash discharge device 11 include a pusher type ash discharge device, a double damper type ash discharge device, a screw type ash discharge device, and the like, and can be appropriately selected from these. Although detailed description of these ash discharge devices by illustration is omitted, a brief description is as follows.

The pusher-type ash discharge device includes an incineration ash storage unit that stores incineration ash from an incinerator and an ash extrusion device that extrudes and discharges the incineration ash stored in this incineration ash storage unit in order from the bottom. Is to be done. In addition, the double damper type ash discharge device is provided with upper dampers and lower dampers arranged vertically inside the chute provided at the discharge port of the incinerator, and operates to drop the incineration ash accumulated on the dampers. The upper and lower dampers alternately drop the incineration ash in stages. Further, the screw type ash discharge device includes a trough capable of receiving incineration ash from an incinerator and a screw blade with a shaft arranged in the trough, and by rotating the screw blade with a shaft, the inside of the trough The incineration ash is configured to be continuously discharged to the downstream side by a screw blade with a shaft.

<Ash transfer device>
The ash transport device 12 transports the incinerated ash discharged by the ash discharge device 11. In the first embodiment, a belt conveyor type ash transfer device is adopted as the ash transfer device 12. The ash transport device 12 includes a square tubular casing 21 extending in the transport direction and a belt conveyor 22 arranged in the casing 21.

The casing 21 has an input port 24 on one side to which the incineration ash discharged from the ash discharge device 11 is charged, and has a discharge port 25 on the other side for discharging the incineration ash conveyed by the belt conveyor 22. doing. The belt conveyor 22 includes drive wheels 26 and trailing wheels 27 that are arranged at predetermined intervals in the transport direction, and endless belts 28 that are wound around the drive wheels 26 and trailing wheels 27 in an endless manner. ing. In the belt conveyor 22, the incineration ash introduced through the inlet 24 of the casing 21 can be conveyed to the discharge port 25 of the casing 21 by the endless belt 28 that orbits by the operation of the drive wheels 26. It has become. The incineration ash discharged from the discharge port 25 is stored in the incineration ash storage facility 29.

In the first embodiment, an example in which a belt conveyor type ash transfer device is adopted as the ash transfer device 12 is shown, but the present invention is not limited to this, and a flight conveyor type ash transfer device may be adopted. The flight conveyor type ash transfer device will not be described in detail by illustration, but will be briefly described as follows.

The flight conveyor type ash transfer device is configured by disposing a flight conveyor in a casing having the same structure as the casing 21 described above. The flight conveyor is close to the drive wheels and the driven wheels that are arranged at predetermined intervals in the transport direction, the endless chains that are wound around the drive wheels and the driven wheels in an endless manner, and the bottom plate of the casing. It is equipped with a plurality of scrapers attached to the endless chain at predetermined intervals so as to be movable. In this flight conveyor, the endless chain orbits due to the operation of the drive wheels, and the scraper attached to the endless chain scrapes the incineration ash accumulated on the bottom plate of the casing and conveys it to the discharge port of the casing. You can do it.

<Water injection nozzle>
The water injection nozzle 13 adds water to the incineration ash conveyed by the belt conveyor 22. A plurality of water injection nozzles 13 are provided on the upper part of the casing 21 so that water can be evenly added (injected) to the incinerated ash in the region on the upstream side in the transport direction of the ash transport device 12 (for convenience of explanation, FIG. Only one is shown in.).

A water supply pipe 31 is connected to the water injection nozzle 13. Water pumped from the water supply source 30 is supplied to the water injection nozzle 13 via the water supply pipe 31. A flow rate adjusting valve 32 is provided in the water supply pipe 31 so that the flow rate of water flowing through the pipe can be adjusted. Further, the water supply pipe 31 is provided with a flow meter 33 so that the flow rate of water flowing through the pipe can be measured.

<Moisture meter>
The moisture meter 14 is provided on the upper part of the casing 21 so as to be located on the downstream side in the transport direction of the ash transport device 12 from the installation position of the water jet nozzle 13, and the moisture content of the incinerated ash in which water is sprayed by the water jet nozzle 13 Measure the rate. As the moisture meter 14, it is preferable that the moisture content contained in the incinerated ash can be continuously measured without contacting the incinerated ash to be conveyed. For example, a microwave moisture meter that measures the moisture content by replacing the amount of electrical change such as attenuation of microwaves irradiated with incineration ash with moisture, and light containing near infrared rays irradiated with incineration ash. A near-infrared moisture meter or the like that measures the moisture content from the reflectance can be preferably used.

<Blow pipe>
The blow pipe 15 is provided in the upper part of the casing 21 so as to be located on the downstream side in the transport direction of the ash transport device 12 from the installation position of the moisture meter 14. The blow pipe 15 is opened toward the inside of the casing 21 so that neutralizing gas (burnt exhaust gas) containing CO ₂ can be blown into the incineration ash conveyed by the belt conveyor 22.

An exhaust gas supply pipe 35 for supplying incinerated exhaust gas after dust and the like are removed by the bug filter 5 is connected to the blow pipe 15. An attracting blower 36 is interposed in the middle of the exhaust gas supply pipe 35, and the incinerated exhaust gas after dust removal is supplied to the blowing pipe 15 by the attracting action of the attracting blower 36. As a result, the incinerated exhaust gas is blown into the incinerated ash conveyed by the belt conveyor 22 by the blowing pipe 15.

<Exhaust section>
The casing 21 is provided with an exhaust portion 37 so as to be located at the most downstream portion in the transport direction of the ash transport device 12. The exhaust portion 37 is composed of a tubular member that opens toward the outside of the casing 21 so that the incinerated exhaust gas blown into the casing 21 through the blow pipe 15 can be discharged to the outside of the casing 21. An exhaust gas exhaust pipe 38 for guiding the incinerated exhaust gas discharged to the outside of the casing 21 to the incinerator 1 is connected to the exhaust unit 37.

<Control device>
The control device 16 is mainly composed of a computer having a CPU, RAM, ROM, an interface circuit, and the like. In the control device 16, a predetermined calculation process is executed based on the measurement signal from the flow meter 33 and the measurement signal from the moisture meter 14, and a predetermined control signal based on the calculation result is transmitted to the flow control valve 32. Then, the amount of water jetted from the water jet nozzle 13 is controlled.

<Operation explanation>
In the incineration ash treatment apparatus 10A configured as described above, the sparingly soluble treatment of heavy metals is performed by carrying out the plurality of steps described below.

<Incineration ash discharge process>
First, the ash discharge device 11 temporarily stores the incineration ash discharged from the incinerator 1 and discharges it as needed (incineration ash discharge step). The incinerated ash discharged from the ash discharge device 11 is charged into the casing 21 via the charging port 24.

<Incineration ash transport process>
The belt conveyor 22 conveys the incineration ash charged into the casing 21 through the inlet 24 to the discharge port 25 (incineration ash transport step). The incineration ash conveyed to the discharge port 25 is discharged from the discharge port 25 and stored in the incineration ash storage facility 29.

<Water addition process>
The water injection nozzle 13 injects water onto the incineration ash conveyed by the belt conveyor 22 (water addition step). The amount of water injected from the water injection nozzle 13 is measured by the flow meter 33, and the measurement signal of the amount of injected water is transmitted to the control device 16.

In the incineration ash treatment apparatus 10A, by carrying out the water addition step, the incineration ash can be extinguished and cooled even if the incineration ash contains still burning waste, and the incineration ash is being transported or loaded. , The incineration ash can be humidified to the extent that the incineration ash can be prevented from being scattered during loading and unloading.

<Moisture content measurement process>
The moisture meter 14 measures the moisture content of the incinerated ash sprayed with water by the water injection nozzle 13 (moisture content measuring step). The moisture content measurement signal is transmitted to the control device 16.

Here, the amount of incinerated ash conveyed by the belt conveyor 22 (hereinafter referred to as "conveyed ash amount") is M, and the amount of jet water (L / h) measured by the flow meter 33 is Q, and the moisture content. When the water content (%) measured by the total 14 is W, the amount of conveyed ash M can be calculated by the following formula (1).
M = (100-W) x Q / W ... (1)

The target moisture content of the ash that is set in advance (%) and W _T, water needed actual moisture content of the ash (measured moisture content W of moisture meter 14) becomes the target water content W _T When the jet water amount (hereinafter referred to as "target jet water amount") is Q _T , the target jet water amount Q _T can be calculated by the following formula (2).
_{Q T = W T × M /} (100 - W T) ··· (2)

The control device 16 reads the moisture content W measured by the moisture meter 14 and the jet water amount Q measured by the flow meter 33, and calculates the conveyed ash amount M by the above formula (1). Then, the control unit 16 based on the conveying ash amount M calculated, calculates a target injection water amount Q _T by the equation (2). Then, the control unit 16, a flow control signal corresponding to the calculated target injection water amount Q _T feed to flow control valve 32, the actual injection quantity of water from the water injection nozzle 13 which is measured by the flow meter 33 is the target injection to control the injection amount of water to match the amount of water Q _T. Accordingly, even if the conveyance amount of ash to be conveyed by the belt conveyor 22 is varied, it is possible to reliably close the moisture content of the ash to the target moisture content W _T.

<Neutralization process>
The blow pipe 15 blows the incineration exhaust gas supplied by the attraction action of the attraction blower 36 into the incineration ash conveyed by the belt conveyor 22 (neutralization step). As a result, incineration exhaust gas (neutralizing gas) containing CO ₂ is added to the incineration ash after water is added by the water injection of the water injection nozzle 13. The incineration exhaust gas is supplied to the inside of the casing 21 for about 1 minute to 12 hours (preferably about 5 minutes to 1 hour).

Heavy metals contained in incineration ash react with CO ₂ contained in incineration exhaust gas to form carbon oxide, and the solubility in water decreases. Among the heavy metals contained in incineration ash, the heavy metals to be treated are mainly lead because of the high content of lead. Lead changes from lead oxide (PbO) to lead carbonate (PbCO ₃ ), which reduces its solubility in water and makes it sparingly soluble. In addition, the incinerated ash is basic and the pH of the eluate is high. Regarding the pH of the incinerated ash, the pH of the incinerated ash is obtained by reacting calcium oxide (CaO) or calcium hydroxide (Ca (OH) ₂ ) contained in the incinerated ash with CO ₂ to obtain calcium carbonate (CaCO ₃ ). Is also set as a sparingly soluble region in which heavy metals show poor solubility. Lead is an amphoteric metal, and in incineration ash showing strong basicity, the elution amount of lead can be reduced by lowering the pH of the eluate to make it a poorly soluble region.

In the ash processing apparatus 10A, such that the actual moisture content of the ash (measured moisture content W of moisture meter 14) becomes the target water content W _T, water against ash carried by the ash feeder 12 Water is added by the injection nozzle 13. Therefore, the water content of the incinerated ash can be suppressed as compared with that of Patent Document 2 in which the incinerated ash is completely submerged, and water can be uniformly added to the incinerated ash. Further, in the incineration ash treatment apparatus 10A, the incineration exhaust gas containing CO ₂ is conveyed by the belt conveyor 22 inside the casing 21 to the incineration ash to which water is uniformly added by the blowing pipe 15. It is blown from directly above. As a result, the incinerated exhaust gas is directly blown into the incinerated ash from the blowing pipe 15 in a state where the emission of the incinerated exhaust gas to the outside is suppressed by the casing 21. Therefore, the incineration exhaust gas penetrates deeper into the incineration ash, and the CO ₂ contained in the incineration exhaust gas can be surely brought into contact with the hydroxides and heavy metals in the incineration ash. Therefore, the reaction between the hydroxide in the incineration ash and CO ₂ and the reaction between the heavy metals in the incineration ash and CO ₂ proceed more efficiently, and the treatment for making the heavy metals sparingly soluble is performed more efficiently. be able to.

The incinerated exhaust gas blown into the casing 21 is exhausted to the incinerator 1 via the exhaust unit 37 and the exhaust gas exhaust pipe 38.

<Process of adding heavy metals elution prevention chemicals>
In the incineration ash treatment apparatus 10A, a heavy metal elution prevention chemical addition step is carried out as necessary. That is, a heavy metal elution prevention agent (chelating agent) is mixed with water pumped from the water supply source 30, and a mixed solution of water and the chelating agent is sprayed from the water injection nozzle 13, so that the chelating agent is added to the incinerated ash. Adhere to. As a result, in addition to the addition of the incinerated exhaust gas to the incinerated ash, the chelating agent is attached to the incinerated ash, so that the synergistic treatment of the sparingly soluble treatment of heavy metals by the incinerated exhaust gas and the stabilization treatment of heavy metals by the chelating agent Due to the effect, elution of heavy metals from incineration ash can be prevented more reliably. In this way, by combining the addition of the incinerated exhaust gas to the incinerated ash and the addition of the chelating agent, the addition of the chelating agent is compared with the case where only the chelating agent is added to the incinerated ash without adding the incinerated exhaust gas. The amount can be reduced.

[Second Embodiment]
FIG. 2 shows a block diagram showing a schematic system of the incineration ash treatment apparatus according to the second embodiment of the present invention. In the second embodiment, the same or similar parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. In the following, the parts specific to the second embodiment will be described. I will mainly explain it.

The incineration ash treatment device 10B according to the second embodiment is the incineration ash treatment device 10A according to the first embodiment to which an exhaust gas recirculation pipe 41 and a recirculation amount control means 50 are added, and other configurations. Is basically the same as the incineration ash treatment apparatus 10A according to the first embodiment.

<Exhaust gas return pipe>
The exhaust gas recirculation pipe 41 is an incineration exhaust gas (unreacted neutralization) containing CO ₂ that was not used for the reaction between the hydroxide in the incineration ash and CO ₂ and the reaction between the heavy metals in the incineration ash and CO _2. It functions as a recirculation means for recirculating the gas) to the blow pipe 15. The exhaust gas return pipe 41 is arranged so as to connect the upstream side of the induction blower 36 in the exhaust gas supply pipe 35 and the exhaust gas exhaust pipe 38.

The recirculation amount control means 50 controls the recirculation amount of the incinerated exhaust gas by the exhaust gas recirculation pipe 41 based on the CO ₂ concentration contained in the incinerated exhaust gas recirculated to the blow pipe 15. The recirculation amount control means 50 is mainly composed of a CO ₂ concentration meter 51, a damper device 52, and a control device 16.

The CO ₂ concentration meter 51 is connected to the exhaust gas supply pipe 35 so that the concentration of CO ₂ contained in the incinerated exhaust gas flowing from the induction blower 36 to the blow pipe 15 can be measured. The damper device 52 is configured so that the damper opening degree can be changed according to a control signal from the control device 16. The control device 16 executes a predetermined calculation process based on the measurement signal from the CO ₂ concentration meter 51, transmits a predetermined control signal based on the calculation result to the damper device 52, and changes the damper opening degree. .. Thereby, the flow rate of the incinerated exhaust gas flowing through the exhaust gas recirculation pipe 41 can be controlled, and the recirculation amount of the incinerated exhaust gas by the exhaust gas recirculation pipe 41 can be controlled.

In the incineration ash treatment device 10B configured as described above, as in the case of the incineration ash treatment device 10A of the first embodiment, the incineration ash treatment device 10B blows air from the bag filter 5 through the exhaust gas supply pipe 35 by the attraction action of the attraction blower 36. The incineration exhaust gas supplied to the pipe 15 is blown into the casing 21 through the blow pipe 15. The incinerated exhaust gas blown into the inside of the casing 21 is exhausted to the incinerator 1 through the exhaust unit 37 and the exhaust gas exhaust pipe 38. A part of the incinerated exhaust gas flowing through the exhaust gas exhaust pipe 38 flows from the exhaust gas return pipe 41 to the exhaust gas supply pipe 35, merges with the incinerated exhaust gas flowing from the bag filter 5 to the blow pipe 15 through the exhaust gas supply pipe 35, and again. , Is blown into the inside of the casing 21 through the blow pipe 15. In this way, the unreacted incinerated exhaust gas is refluxed, so that CO ₂ contained in the incinerated exhaust gas can be used without waste for the sparing treatment of heavy metals.

In ash processing apparatus 10B, the CO ₂ concentration is predetermined range measured by the CO ₂ concentration meter 51 (e.g., 5-20%) when it becomes lower than the lower limit of (5%), the control unit 16, the recirculation amount A control signal for reducing the damper opening degree is transmitted to the damper device 52 so as to reduce the amount of carbon dioxide. As a result, the amount of incinerated exhaust gas recirculated by the exhaust gas recirculation pipe 41 is reduced. When the amount of recirculation decreases, the flow rate of the incinerated exhaust gas flowing from the bag filter 5 to the blow pipe 15 via the exhaust gas supply pipe 35 is relatively increased, and the incineration blown into the casing 21 through the blow pipe 15 The CO ₂ concentration in the exhaust gas is increased.

In the incineration ash treatment apparatus 10B, the CO ₂ concentration in the incineration exhaust gas blown into the casing 21 through the blow pipe 15 is kept within a predetermined range (for example, 5 to 20%) by the above-mentioned recirculation amount control. As a result, CO ₂ contained in the incinerated exhaust gas can be used without waste for the sparing treatment of heavy metals while stably performing the sparing treatment of heavy metals.

[Third Embodiment]
FIG. 3 shows a block diagram showing a schematic system of the incineration ash treatment apparatus according to the third embodiment of the present invention. In the third embodiment, the same or similar parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted. In the following, the parts specific to the third embodiment will be described. I will mainly explain it.

The incineration ash treatment apparatus 10C according to the third embodiment has a configuration for suppressing the elution amount of heavy metals to the elution reference value or less even if the content of heavy metals contained in the incineration ash fluctuates (increases). It is characterized by. The specific configuration and processing contents will be described below. Among the heavy metals contained in the incineration ash, the heavy metals to be treated are mainly lead because the content of lead is particularly high. Therefore, in the following, lead will be described as an example of treatment, but the treatment described below can be similarly applied to heavy metals other than lead.

The incineration ash treatment device 10C according to the third embodiment includes a lead content measuring device 71, a chemical addition device 72, and a chemical addition amount control means 73.

<Lead content measuring device>
The lead content measuring device 71 measures the lead content contained in the incineration ash conveyed by the belt conveyor 22. The lead content measuring device 71 is provided in the upper part (or lower part) of the casing 21 so as to be located on the upstream side in the transporting direction of the ash transporting device 12 from the installation position of the water injection nozzle 13. The lead content measuring device 71 includes lead contained in incineration ash before water is injected by the water injection nozzle 13 and, as a matter of course, before neutralizing gas (incineration exhaust gas) is blown by the blowing pipe 15. The content of is measured. As the lead content measuring device 71, for example, a fluorescent X-ray analyzer, a voltammetry device, an atomic absorption spectrophotometer, an ICP emission spectrometer, a laser-induced breakdown spectrophotometer, or the like can be preferably used.

<Drug addition device>
The chemical addition device 72 adds a chelating agent (heavy metal elution prevention agent) for preventing the elution of heavy metals to the incineration ash conveyed by the belt conveyor 22. The drug addition device 72 includes a drug storage tank 81 for storing the chelating agent, a drug supply pipe 82 for connecting the drug storage tank 81 and the water supply pipe 31, and a pump 83 arranged in the middle of the drug supply pipe 82. It is configured with. In the drug addition device 72, the chelating agent stored in the drug storage tank 81 is pumped to the water supply pipe 31 through the drug supply pipe 82 by the operation of the pump 83. As a result, the chelating agent is mixed with the water injected from the water injection nozzle 13, and the chelating agent can be added together with the water to the incineration ash on the belt conveyor 22.

<Drug addition amount control means>
The drug addition amount control means 73 controls the addition amount of the chelating agent added by the drug addition device 72. The drug addition amount control means 73 includes the control device 16, a flow rate control valve 85 for adjusting the flow rate of the chelating agent flowing through the drug supply pipe 82, and a flow meter 86 for measuring the flow rate of the chelating agent flowing through the drug supply pipe 82. It is configured with.

The content of lead contained in the incineration ash and water is added to the incineration ash by the water injection nozzle 13 and the neutralizing gas (incineration exhaust gas) is added to the storage unit 18 in the control device 16. The data on the relationship between the lead elution amount and the lead elution amount (hereinafter referred to as "relationship data between the lead content and the lead elution amount") is stored.

FIG. 4 is a flowchart showing a procedure for treating incineration ash by the incineration ash treatment apparatus according to the third embodiment of the present invention. The operation of adding the chelating agent to the incinerated ash will be described with reference to the flowchart of FIG. 4 and the block diagram of FIG. In the flowchart of FIG. 4, the symbol “S” in the figure represents a step.

(Heavy metal content measurement process)
The control device 16 takes in the measured value of the lead content measured by the lead content measuring device 71 (S1).

(Heavy metal elution amount calculation process)
Next, the control device 16 reads out the relationship data between the lead content and the lead elution amount from the storage unit 18, and based on the read relationship data between the lead content and the lead elution amount, the lead content taken in in step S1. The amount of lead elution is calculated from the measured value of (S2).

(Chemical addition amount calculation process)
Next, the control device 16 is required to reduce the lead elution amount to the elution reference value or less when the lead elution amount calculated by the calculation in step S2 exceeds the elution reference value (“YES” in step S3). The amount of the chelating agent added is calculated (S4).

(Chemical addition amount control process)
Then, the control device 16 feeds back the measurement signal of the flow meter 86 and chelate while transmitting a predetermined flow rate control signal to the flow rate control valve 85 so that the addition amount is calculated by the calculation in step S4. The amount of the agent added is controlled (S5).

According to the incineration ash treatment device 10C according to the third embodiment, in addition to the same action and effect as the incineration ash treatment device 10A according to the first embodiment, the following actions and effects can be obtained. That is, in the incineration ash treatment device 10C according to the third embodiment, the lead content measuring device 71 is based on the relationship data between the lead content and the lead elution amount stored in advance in the storage unit 18 of the control device 16. The lead elution amount is calculated from the lead content measured by. When the calculated lead elution amount exceeds the elution reference value, the amount of the chelating agent added to bring the lead elution amount to the elution standard value or less is calculated. Then, the addition amount of the chelating agent added by the drug addition device 72 is controlled so as to be the calculated addition amount. Therefore, depending on the fluctuation of the lead content in the incineration ash, even if the elution amount of lead exceeds the elution standard value even by the sparing treatment by adding water and neutralizing gas, the lead content The amount of elution can be suppressed below the elution standard value.

The incineration ash treatment apparatus and the incineration ash treatment method of the present invention have been described above based on a plurality of embodiments, but the present invention is not limited to the configurations described in the above embodiments, and the gist thereof is described. The configuration can be changed as appropriate within a range that does not deviate. Specific other embodiments are as follows.

<Separate Embodiment 1>
In each of the above embodiments, the neutralization step is carried out by blowing the incinerated exhaust gas into the incineration ash as a neutralizing gas, but the present invention is not limited to this. For example, Dari blown into ash CO ₂ enriched gas from the incineration exhaust gas or biogas was separated and recovered by using a membrane separation unit and the CO ₂ absorbing solution (CO ₂ concentration is more than 99% by volume at room temperature) as the neutralizing gas, The neutralization step may be carried out by blowing liquefied carbon dioxide gas (CO ₂ concentration at room temperature of 99% by volume or more) filled in the bomb into incineration ash as a neutralizing gas.

<Separate Embodiment 2>
In each of the above embodiments, an example is shown in which the blow pipe 15 is provided in the casing 21 capable of accommodating the entire belt conveyor 22 that conveys the incineration ash, but the present invention is not limited thereto. For example, as shown by the alternate long and short dash line with reference numerals 60 in FIGS. 1 and 2, a hood 60 covering a part of the belt conveyor 22 may be provided, and a blow pipe 15 may be provided in the hood 60.

<Separate Embodiment 3>
Further, in the first embodiment described above, in order to reduce power consumption, the incineration ash discharge means (ash discharge device 11) is set to intermittent operation, and the incineration ash transport means (ash transport) is set in accordance with the operation of the incineration ash discharge means. The transport operation of the device 12), the water addition operation of the water addition means (water injection nozzle 13), and the neutralization gas addition operation of the neutralizing means (blow-in pipe 15) may be linked.

<Separate Embodiment 4>
Further, in the second embodiment described above, in order to reduce power consumption, the incineration ash discharge means (ash discharge device 11) is set to intermittent operation, and the incineration ash transport means (ash transport) is set in accordance with the operation of the incineration ash discharge means. The transport operation of the device 12), the water addition operation of the water addition means (water injection nozzle 13), the neutralization gas addition operation of the neutralization means (blow-in pipe 15), and the control of the recirculation amount control means 50 are linked. You may do so.

The incineration ash treatment apparatus and the incineration ash treatment method of the present invention can be used, for example, in an application of suppressing elution of heavy metals contained in incineration ash generated by incineration of municipal waste, industrial waste and the like.

10A, 10B, 10C Incineration ash processing device 12 Ash transfer device (incineration ash transfer means)
13 Water injection nozzle (water addition means)
15 Blowing pipe (neutralizing means)
16 Control device 21 Casing 41 Exhaust gas reflux pipe (reflux means)
50 Circulation control means 71 Lead content measuring device (heavy metal content measuring means)
72 Drug addition device (drug addition means)
73 Drug addition amount control means

Claims (9)

Incineration ash transport means for transporting incineration ash and
A water addition means for adding water to the incineration ash transported by the incineration ash transport means,
A neutralizing means for adding a neutralizing gas containing CO ₂ to the incineration ash to which water has been added by the water adding means, and a neutralizing means.
An incineration ash processing device equipped with. The incineration ash treatment apparatus according to claim 1, wherein the neutralizing means is a blowing pipe for blowing the neutralizing gas. The incineration ash treatment apparatus according to claim 1 or 2, further comprising a casing capable of containing the incineration ash to which the neutralizing gas is added. The incineration ash treatment apparatus according to any one of claims 1 to 3, further comprising a reflux means for refluxing the unreacted neutralizing gas to the neutralizing means. The incineration ash treatment apparatus according to claim 4, further comprising a recirculation amount control means for controlling the recirculation amount by the recirculation means based on the CO ₂ concentration in the neutralizing gas. The heavy metal elution prevention agent for preventing the elution of heavy metals is directly added to the incineration ash transported by the incineration ash transport means, or the heavy metal elution prevention agent is added by the water addition means. The incineration ash treatment apparatus according to any one of claims 1 to 5, wherein the heavy metal elution prevention agent adheres to the incineration ash by mixing with water. A heavy metal content measuring means for measuring the content of heavy metals contained in the incineration ash transported by the incineration ash transporting means, and a heavy metal content measuring means.
A chemical addition means for adding a heavy metal elution prevention agent to the incineration ash transported by the incineration ash transport means to prevent the elution of heavy metals.
A drug addition amount control means for controlling the addition amount of the heavy metal elution prevention drug added by the drug addition means is provided.
The chemical addition amount control means includes the content of heavy metals contained in the incineration ash and the heavy metals when water is added to the incineration ash by the water addition means and the neutralizing gas is added by the neutralization means. The elution amount of heavy metals is calculated from the content of heavy metals measured by the heavy metals content measuring means based on the relationship data with the elution amount of the heavy metals, and the calculated elution amount of the heavy metals is the elution reference value. If it exceeds, the amount of the heavy metal elution prevention agent added required to bring the amount of heavy metals elution to the elution reference value or less is calculated, and the amount added by the agent addition means is calculated. The incineration ash treatment apparatus according to any one of claims 1 to 5, which controls the amount of the heavy metal elution prevention agent added. The incineration ash transport process for transporting incineration ash and
A water addition step of adding water to the incineration ash transported by the incineration ash transfer step, and a water addition step.
A neutralization step of adding a neutralizing gas containing CO ₂ to the incineration ash to which water was added by the water addition step, and a neutralization step.
Incineration ash treatment method including. A heavy metal content measuring step for measuring the content of heavy metals contained in the incineration ash transported by the incineration ash transport step, and a heavy metal content measuring step.
Relationship data between the content of heavy metals contained in the incineration ash and the elution amount of heavy metals when water is added to the incineration ash by the water addition step and the neutralizing gas is added by the neutralization step. Based on the above, a heavy metal elution amount calculation step of calculating the elution amount of heavy metals from the heavy metal content measured by the heavy metal content measurement step,
When the elution amount of heavy metals calculated in the heavy metal elution amount calculation step exceeds the elution standard value, the amount of the heavy metal elution prevention agent added to keep the elution amount of heavy metals below the elution standard value is calculated. Chemical addition amount calculation process and
A chemical addition amount control step for controlling the addition amount of the heavy metal elution prevention chemical to the incineration ash transported by the incineration ash transport step so that the addition amount is calculated in the chemical addition amount calculation step.
The incineration ash treatment method according to claim 8, further comprising.

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