JP2007196153A - Ash treatment method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ash treatment method and apparatus which inexpensively materialize improvement in the property and state of ash dust so that the amount thereof is reduced to an extent enabling the ash dust to be efficiently treated by, for example, an ash dust recycling process, and which can utilize digestion gas to be generated in a methane fermentation apparatus. <P>SOLUTION: The ash treatment method is provided in which ash is treated by charging carbon dioxide to an ash water-washing unit for water-washing the ash generated at incineration equipment for incinerating waste and contacting the carbon dioxide with the generated ash. The ash treatment method is characterized in that the methane fermentation apparatus for methane-fermenting waste is arranged in juxtaposition with the incineration equipment and at least a part of the digestion gas generated in the methane fermentation apparatus is directly or indirectly charged to the ash water-washing unit as a carbon dioxide supply source to contact the digestion gas with the ash. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to processing of waste such as general waste and industrial waste, and more particularly to processing of ash generated after incineration of waste.

Conventionally, general waste such as municipal waste and sewage sludge or industrial waste discharged from various factories has been treated by incineration for volume reduction and detoxification. In general, ash dust treatment methods such as main ash discharged from the bottom of an incinerator, which is an incinerator, and fly ash collected from exhaust gas include landfill, molten slag, and recycling of building materials. Can be mentioned. In particular, in recent years, it has been demanded that these ashes be processed into products such as artificial aggregates, planting soil, roadbed materials, roadbed materials, fired tiles, and effectively used. The ash dust discharged from the incinerator contains heavy metals, dioxins, SO _x , salts, and the like, and it is necessary to reduce these substances to below the standard value depending on the use of the ash. Since heavy metals and dioxins are harmful to the human body and the environment, they are required to be reduced in any treatment, and SO _x and salts are required to be reduced when ash is reused. The

Various proposals and practical applications for the treatment of ash dust discharged from incinerators have been made.
For example, in Patent Document 1 and Patent Document 2, fly ash generated from an incinerator is washed, heavy metals and salts are transferred to the solution side, and then dehydrated and returned to the incinerator to thermally decompose dioxins. A processing method is disclosed. Since heavy metals and salts in fly ash are easy to elute in water, they are removed by washing with water, and dioxins that are difficult to elute are decomposed and reduced by re-introducing them into the furnace. However, in this method, the content of heavy metals is not sufficiently reduced, and the elution of heavy metals does not reach the soil environmental standards. Although salt can be reduced by washing with water, washing with water alone is not enough to recycle ash. In addition, when a calcium-based compound is used as the exhaust gas neutralizer, CaSO ₄ produced by the neutralization reaction is hardly soluble, and therefore remains in the dehydrated cake after washing with fly ash water. For this reason, SO _x is generated when heated by recharging the furnace, and the amount of exhaust gas neutralizing agent used is increased.

  The reason why it is difficult to reduce the salt to an extent sufficient for the reuse of ash is that the salt is contained in the form of a hardly soluble Friedel salt. Chlorine contained in Friedel's salt does not elute only by washing with water, and remains on the solid side after dehydration. Therefore, there is a method disclosed in Patent Document 3 as a countermeasure against hardly soluble salts that cannot be removed by washing with water. This is because ash dust is washed with a solution having a chlorine ion concentration of 2.0 wt% or more to promote the elution of heavy metals contained in ash dust, and carbon dioxide is introduced into the ash dust washing suspension and washed. Promotes the elution of chloride ions from Friedel's salt contained in However, in this method, standard gas and combustion exhaust gas are assumed as the carbon dioxide supply source. The standard gas is expensive, and the combustion exhaust gas has a low carbon dioxide concentration. Therefore, there is a problem that a large-sized gas supply blower is necessary. Furthermore, since calcium chloride and sodium chloride are used as the supply source of chlorine ions, chemical costs are incurred and the cost is high, and the chlorine ion concentration of the cleaning suspension is as high as 2.0% or more, so after washing However, there is a problem in that soluble chlorine ions cannot be removed by dehydration of the water, and the amount of washing water in washing filtration becomes excessive.

  Moreover, the method of processing a low-calorie waste etc. with a methane fermentation apparatus is mention | raise | lifted as a processing method of the waste conventionally performed different from the said incineration. Digestion gas generated in the methane fermentation apparatus can be effectively used as fuel by using combustion energy of methane. Therefore, conventionally, a method of supplying digestion gas generated from a methane fermentation apparatus as fuel has been performed, and when processing waste including organic waste, supply of external fuel is reduced as much as possible to reduce the processing cost. A method for significantly reducing this is disclosed in Patent Document 4. This is to supply digestion gas generated from a methane fermentation apparatus to a heat treatment apparatus when heat treatment is performed by a heat treatment apparatus that heats all or part of the waste including organic waste. However, this method is not sufficient in terms of effective utilization of carbon dioxide, which is a component that occupies a large proportion of digestion gas, only to supply digestion gas generated from the methane fermentation apparatus to the heat treatment apparatus and external power source. Yes, it cannot be said that digestive gas is fully utilized effectively.

Japanese Patent No. 3492191 JP 2000-227214 A JP-A-10-128304 JP 2003-275722 A

As mentioned above, the main ash and fly ash generated in the incineration facilities contain salts, heavy metals, dioxins, etc., which are used for landfill treatment or ash recycling. It is a problem to reduce at low cost, and it is a problem to effectively utilize digestion gas generated in a methane fermentation apparatus.
Therefore, in view of the above-mentioned problems of the prior art, the present invention is to improve the properties of ash dust efficiently up to the amount that can be recycled or less, and to effectively utilize the digestion gas generated in the methane fermentation apparatus. It is an object of the present invention to provide an ash treatment method and an apparatus for the same.

Therefore, in order to solve this problem, the present invention provides:
In an ash treatment method for treating ash by injecting carbon dioxide into an ash water washing apparatus for washing ash generated in incineration equipment for incineration of waste and bringing it into contact with ash,
A methane fermentation apparatus for treating waste with methane fermentation is installed in the incineration facility, and at least a part of the digestion gas generated in the methane fermentation apparatus is directly or indirectly introduced into the ash water washing apparatus as a carbon dioxide supply source. It is characterized by treating ash by contact.
The contact of ash and carbon dioxide in the ash water washing device can be solid-gas contact where solid ash and gaseous carbon dioxide are contacted, but hydrogen sulfide and odorous substances, which are acidic impurities, are alkaline and ash washing water slurry In order to dissolve well, the digestion gas is dissolved in water and the water in which the digestion gas is dissolved is used as washing water in the ash washing apparatus, and the contact is performed under wet conditions in which the ash and carbon dioxide contained in the digestion gas are contacted. It is preferable that desulfurization and deodorization effects can be expected.
According to the present invention, the amount of elution due to carbonation of heavy metals can be expected by carbon dioxide contained in the digestion gas by blowing the digestion gas into the ash water washing apparatus. In addition, elution of sparingly soluble chlorine compounds such as Friedel's salt can be expected. The eluted slightly soluble chlorine compound is washed away with an ash water washing apparatus. In addition, since the carbon dioxide in the digestion gas is recycled as a carbon dioxide supply source of the ash treatment material, the digestion gas can be used effectively.

In addition, it is characterized in that at least a part of the combustion exhaust gas obtained by burning the digestion gas generated in the methane fermentation apparatus is indirectly introduced into the ash water washing apparatus as a carbon dioxide supply source.
Digestion gas can be effectively utilized by putting the combustion exhaust gas into an ash water washing apparatus, and the combustion exhaust gas contains about 10 vol% carbon dioxide, so that elution of chloride is promoted and the content is reduced. The property of ash dust can be improved.

Further, at least a part of digestion gas generated in the methane fermentation apparatus is directly fed into the ash water washing apparatus as a carbon dioxide supply source.
The digestion gas can be effectively utilized by putting the digestion gas into the ash water washing apparatus, and the digestion gas contains about 30 to 40 vol% carbon dioxide, and has a higher carbon dioxide concentration than the combustion exhaust gas. The effect of reducing the content by promoting the elution of chloride in the water washing apparatus is high.

In addition, at least a part of the carbon dioxide gas obtained by concentrating carbon dioxide in the digestion gas generated in the methane fermentation apparatus is indirectly supplied to the ash water washing apparatus as a carbon dioxide supply source.
Furthermore, carbon dioxide in the digestion gas generated in the methane fermentation apparatus is concentrated by a VPSA method (vacuum regeneration pressure swing method).
For example, in the VPSA method, trace harmful substances are separated and removed from digestion gas, and then separated into methane gas and carbon dioxide gas, which are the main components of digestion gas. The carbon dioxide concentration of the carbon dioxide gas obtained by the VPSA method is usually 90% or more, and the carbon dioxide concentration is higher than that of using the combustion exhaust gas or the digestion gas as it is. The effect of reducing the amount is also increased.

Furthermore, it has a step of performing acid cleaning, alkali cleaning and activated carbon treatment on the odor gas generated in the methane fermentation apparatus, using the water containing carbon dioxide as the acid cleaning liquid, and washing with water in the ash water cleaning apparatus as the alkali cleaning liquid The waste activated carbon after use is burned in an incinerator using activated carbon treatment.
The odor gas generated in the methane fermentation equipment contains alkaline substances such as ammonia and hydrogen sulfide, and acidic substances such as organic acids. Therefore, alkaline substances are usually removed by acid cleaning, and acidic substances are removed by alkaline cleaning. And then released through activated carbon. According to the present invention, by using water in which a digestion gas containing carbon dioxide is directly or indirectly added to the acid cleaning liquid, and using the waste water after being washed in the ash water washing apparatus to the alkaline cleaning liquid, the acid cleaning liquid and There is no need to input an alkali cleaning liquid from the outside, and the cleaning liquid cost can be reduced and the cleaning liquid input process can be reduced. Furthermore, by throwing waste activated carbon, which is usually treated as industrial waste, into an incineration facility and burning it, the treatment cost of the waste activated carbon can be reduced, and an effect as a combustion aid can be expected.

Moreover, at least a part of the odor gas generated in the methane fermentation apparatus is blown as a part of the combustion air of the incineration facility.
Thereby, the treatment equipment for the odor gas can be simplified and stably operated. The more odor gas that is blown into the incineration equipment, the more simplified the odor gas treatment equipment can be, and the total amount makes odor gas treatment equipment unnecessary, so it is optimal in terms of simplification. It is. In addition, when an odor gas treatment facility is used, for example, because there is an existing odor gas treatment facility, a part of the combustion air contains digestion gas that exceeds the amount that can be stably processed by the odor gas treatment facility. As a result, the odor gas treatment facility can be stably operated. In this case, for example, the odor gas may be supplied to the odor gas treatment facility in a fixed amount by using a flow rate control valve or the like, and the rest may be blown into the incineration facility.
In addition, the odor gas can be blown into the combustion air and blown in as part of the combustion air, blown in with the secondary air, or blown in with the odor of the waste pit to be put into the incineration facility. The position is not particularly limited as long as the position can be blown into.

Furthermore, the digested sludge generated in the methane fermentation apparatus is incinerated in an incineration facility.
This can simplify the digested sludge treatment facility.

Moreover, it has a dehydration process which dehydrates the digested sludge which generate | occur | produced in the methane fermentation apparatus, It puts into the incineration equipment and incinerates the dehydration separation liquid generate | occur | produced at the said dehydration process, It is characterized by the above-mentioned.
Digested sludge can be reused after dehydration and composting or carbonization. Conventionally, the dehydrated separation liquid after the dehydration treatment needs to be drained by the waste water treatment facility, but the present invention eliminates the need for the waste water treatment facility.

  Here, in the method of incinerating the digested sludge in the incineration facility, the digested sludge cannot be reused, but the digested sludge treatment facility including the dehydration treatment can be simplified, and the dehydrated separation liquid The method of incineration of incinerators requires dehydration equipment, but it has the feature that digested sludge can be reused, so which method is used depending on whether or not the digested sludge is reused. You should decide whether to use it.

  Claim 9 is an invention related to an apparatus configuration embodying the present invention, in which ash is treated by introducing carbon dioxide into an ash washing apparatus for washing ash generated in an incineration facility for incinerating waste and bringing it into contact with the ash. In the ash treatment apparatus configured to perform, methane fermentation apparatus for methane fermentation of waste is provided in the incineration facility, and at least a part of digestion gas generated in the methane fermentation apparatus is washed with ash water using carbon dioxide supply source The present invention is characterized in that the ash is treated by being directly or indirectly introduced into the apparatus and brought into contact with the ash.

As described above, according to the present invention, at least a part of the digestion gas generated in the methane fermentation apparatus is directly or directly to the ash water washing apparatus attached to the incineration facility provided with the methane fermentation apparatus for treating the waste with methane fermentation. By indirect introduction, carbon dioxide comes into contact with the ash, the immobilization of heavy metals, and the elution of poorly soluble chlorine compounds such as Friedel's salt can be effectively achieved and the chloride content can be reduced.
Moreover, since the digestion gas generated in the methane fermentation apparatus is used as a carbon dioxide supply source, the digestion gas can be effectively used.
Further, the carbon dioxide content in the digestion gas is concentrated by, for example, the VPSA method (vacuum regeneration pressure swing method) and the like, and is introduced into the ash water washing apparatus as a carbon dioxide supply source, thereby further reducing the chloride content. .
Moreover, the odor gas and digested sludge which generate | occur | produced in the methane fermentation tank can also be processed efficiently.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is an overall configuration diagram of the ash treatment according to the first embodiment. In this embodiment, low-moisture content high-calorie waste 31a such as plastic and vegetation is classified into low-calorie waste 31b such as raw garbage, manure, sludge, and paper, and these are separated into different processing systems. To process. The high calorie waste 31a is incinerated in the stoker incinerator 10, and the low calorie waste 31b is in methane fermentation in the methane fermentation apparatus 50.

  Waste such as municipal waste, sludge, industrial waste, etc. is separated by high-calorie waste 31a with low water content, such as plastic and vegetation, and low-calorie waste 31b with high water content, such as kitchen waste, manure, sludge, and paper. It is divided into. Examples of the separation method include separation and collection for separating and collecting waste, and specific gravity selection for sorting by specific gravity. Any method may be used as long as the separation can be performed.

  First, the high calorie waste 31a is incinerated in the stoker type incinerator 10. The stoker-type incinerator 10 includes a waste charging hopper 11, a grate 12 that moves the high-calorie waste 31 a charged from the garbage charging hopper 11 through the furnace while stirring, and a combustion grate from below the grate 12. A primary air inlet 13 for introducing air (primary air) 15, a primary combustion chamber 16 formed on a grate, a main ash outlet 14 for discharging main ash 36 after combustion, and the primary combustion chamber 16 , A secondary combustion chamber 18 for completely burning unburned gas in the gas by introducing the secondary air 17, and an ash cooling device 27 for cooling the main ash 36 discharged from the main ash outlet 14. . In the present embodiment, the stoker type incinerator 10 is described as an example, but the present invention is not limited to this, and other incinerators such as a fluidized bed incinerator and a rotary kiln type incinerator may be used.

A boiler 20 is disposed downstream of the stoker-type incinerator 10, and exhaust gas from the incinerator 10 is heat-recovered by the boiler 20 and then introduced into the temperature reducing tower 21. In the temperature reducing tower 21, the exhaust gas is cooled by spraying cooling water. The exhaust gas cooled in the temperature reducing tower 21 is introduced into the dust removing device 22. As the dust removing device 22, a bag filter, a cyclone type dust collector, an electric dust collector or the like is used, and a bag filter is preferably used. At this time, the exhaust gas neutralizing agent 32 is sprayed in the exhaust gas pipe line on the upstream side of the dust removing device 22 or the temperature reducing tower 21. The neutralizing agent 32 is a chemical that removes acidic gases such as HCl and SO _x in the exhaust gas by a neutralization reaction. For example, slaked lime (Ca (OH) ₂ ), caustic soda (NaOH), or sodium bicarbonate (NaHCO ₃ ). Alkali neutralizing agents such as Na-based neutralizing agents are used alone or in combination. The exhaust gas from which the fly ash 33 has been removed by the dust removing device 22 is discharged from the chimney 23 to the outside of the system. In addition, a catalytic reaction tower may be installed after the dust removing device.

Further, a fly ash treatment system for treating the fly ash 33 collected by the boiler 20, the temperature reducing tower 21, the dust removing device 22, or the like, and main ash discharged from the bottom of the stoker incinerator 10 And a main ash processing system for processing 36.
The fly ash treatment system includes a fly ash water washing device 24 for washing the collected fly ash 33 and a dehydrator 25 for dehydrating the washed fly ash, and further treating waste water generated by the dehydrator 25. The waste water treatment facility 26 is provided.
The fly ash water washing device 24 is a device for washing the fly ash 33 with the washing water supplied into the water tank. At this time, if necessary, a stirring means may be provided and washed with water while stirring. L / S (liquid / solid weight ratio) at the time of water washing needs to be 1-10, and it is preferable that it is 3-7. The fly ash water washing device 24 can use either a batch type or a continuous type, but in this embodiment, a batch type water washing device is preferable. In the batch type water washing apparatus, more effective washing is possible by performing washing a plurality of times, and the cost is reduced. Desirably, L / S is made small in the first water washing, and L / S is made equal to or more than the first time in the second and subsequent times. This is because approximately 100 wt% of the salt dissolves in water, but remains in the adhering water of the dehydrated cake, so that the adhering water is separated after the second time after being dissolved and dehydrated in the first time. . A plurality of cleanings may be performed with one apparatus, or a plurality of apparatuses may be arranged in series. Moreover, in the case of a batch-type washing apparatus, it is preferable to operate by alternately providing a plurality of washing water tanks.

The fly ash water washing device 24 simultaneously removes heavy metals contained in the fly ash and salts and sulfur components that are easily eluted in water. As a result, heavy metals and salts move to the liquid side, are separated into solid and liquid by the dehydrator 25, are contained in the waste water, and are fed to the waste water treatment facility 26. At this time, according to the experiment, about 90 to 100 wt% of Cl and about 20 to 50 wt% of Pb contained in the fly ash moved to the liquid side. The waste water treatment facility 26 is mainly composed of a device for removing heavy metals. For example, chelate treatment, coagulation sedimentation treatment, and advanced water treatment are performed. Wastewater after wastewater treatment is discharged.
In the dehydrator 25, dioxins in the fly ash are hardly soluble in water, and therefore remain on the solid side.
The solid material separated by solid-liquid separation by the dehydrator 25, that is, the dehydrated cake 35, is guided to the waste pit of the incinerator 10 or the charging hopper 11 at the subsequent stage, and re-entered into the furnace. In the dehydrated cake 35, dioxins are thermally decomposed and removed by recharging into the furnace, and the remaining heavy metals such as Pb and salts are volatilized and move to the exhaust gas side. At this time, the fly ash 33 is returned to the furnace as the dehydrated cake 35 which is a cake-like lump by the dehydrator 25, so that it is difficult for the fly ash 33 to re-scatter even if it is re-entered into the furnace.

On the other hand, the main ash treatment system includes a sorting device 28 that sorts iron and aluminum from the main ash 36 discharged from the incinerator 10, a pulverizer 29 that pulverizes the main ash 36 into fine particles, and the pulverized main ash 36. And a main ash water washing device 30 for washing the ash with water. Unlike the fly ash 33, the main ash 36 has a large particle size and a small specific surface area, so it is preferable to grind the ash to about 2 to 5 mm. The sorting apparatus 28 and the pulverizer 29 are most preferably configured as described in the present embodiment, but these are appropriately installed, and the arrangement configuration is not particularly limited.
The main ash water washing apparatus 30 has a configuration substantially similar to the above-described fly ash water washing apparatus 24. Furthermore, in this embodiment, the waste water 39 supplied to the main ash water washing device 30 and used for washing is introduced into the fly ash water washing device 24 and reused for washing the fly ash 33 with water. At this time, at least a part of the waste water 39 is reused, but preferably the entire amount is reused. The waste water 39 discharged from the main ash water washing device 30 may be processed by the waste water treatment facility 26 and discharged out of the system without being fed to the fly ash water washing device 24.

Thus, by washing the main ash 36 with the main ash water washing apparatus 30, the salt concentration in the main ash is reduced to a very low value, and the property is suitable for the raw material 38 of cement / concrete products. Can do.
Further, the wastewater 39 used for washing the main ash 36 in the main ash water washing apparatus 30 is supplied to the fly ash water washing apparatus 24 and reused, so that the amount of generated wastewater can be greatly reduced.
Generally, the salt content in the main ash 36 is 0.3 to 2.0%, while the salt content in the fly ash 33 is as high as 7 to 15%. Therefore, in the main ash water washing apparatus 30, by washing the main ash 36 with cleaning water that does not contain salts, the salt removal rate of the main ash 36 can be made extremely high, and resources such as cement and concrete raw materials can be recycled. It is possible to obtain a property suitable for. On the other hand, the fly ash water washing device 24 is configured to wash the fly ash 33 using the waste water after washing with the main ash water. However, since the fly ash 33 is re-introduced into the furnace, there is no problem even if some salt remains. First, the fly ash 33 containing high-concentration salts is roughly washed.
In addition, fly ash that is re-injected into the furnace as the dehydrated cake 35 passes through the high-temperature furnace, so that dioxins are thermally decomposed and removed, and heavy metals and salts are volatilized and move to the exhaust gas side. The salt and heavy metal concentrations in the dewatered cake 35 discharged together with the main ash 36 are reduced.

On the other hand, the low calorie waste 31b is subjected to methane fermentation treatment in the methane fermentation apparatus 50. The digested gas 51 generated in the methane fermentation apparatus 50 is combusted in the combustion apparatus 54 and a combustion exhaust gas 55 is generated. In general, most of the components of the digestion gas 51 generated in the methane fermentation apparatus 50 are methane gas, and additionally contain about 30 to 40 vol% of carbon dioxide. Therefore, the combustion exhaust gas 55 contains about 10 vol% carbon dioxide.
For example, Table 1 summarizes the volume of each component in the flue gas when methane gas is completely burned with 1 m ³ of digestion gas containing 40 vol% carbon dioxide and 60 vol% methane gas under the condition of an air ratio of 1.3. Digestion gas 1 m ³ contains methane gas (CH ₄ ) 0.6 m ³ and carbon dioxide (CO ₂ ) 0.4 m ³ . Further, since the combustion reaction of methane gas can be expressed by the following reaction formula (1), oxygen (O ₂ ) in the combustion air is 0.6 × 2 × 1 under the condition of an air ratio of 1.3. .3 = 1.56 m ³ .
CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O (1)
Further, since the volume ratio of oxygen (O ₂ ) and nitrogen (N ₂ ) in the air is 0.21: 0.79, the nitrogen (N ₂ ) in the combustion air is 1.56 × 0.79 / 0. .21 = 5.87 m ³ . Therefore, when 1 m ³ of digestion gas is burned under the condition of an air ratio of 1.3, the combustion reaction of (1) occurs, and carbon dioxide (CO ₂ ) 0.6 m ³ and water (H ₂ O) 1. 2m ³ is produced. Therefore, the carbon dioxide (CO ₂ ) in the combustion exhaust gas is (0.4 + 0.6) / (1 + 0.27 + 5.87) = 14 vol%.

  Therefore, by blowing the combustion exhaust gas 55 into the main ash water washing device 30 or the feed water 37 supplied to the main ash supply device 30, the amount of elution due to carbonation of heavy metals is suppressed, and a hardly soluble substance such as Friedel's salt is used. Chlorine compounds can be eluted, and reduction of chloride content can be promoted. The eluted slightly soluble chlorine compound is washed away with an ash water washing apparatus. Further, since the digestion gas is recycled as the carbon dioxide supply source, the digestion gas can be effectively used.

Further, in order to promote the reduction of the chloride content as described above, the ash slurry in the main ash water washing apparatus 30 and the carbon dioxide in the combustion exhaust gas 55 are mixed, and the ash and carbon dioxide are efficiently brought into contact with each other. Although necessary, this mixing can be carried out in a single tank or in multiple tanks.
The configuration shown in FIG. 8 is an example in which mixing is performed in a single tank or a plurality of tanks. FIG. 8A is a configuration diagram in the case of mixing ash slurry and carbon dioxide (combustion exhaust gas) in a single tank, and FIG. 8B is a mixture of ash slurry and carbon dioxide (combustion exhaust gas) in a plurality of (2) tanks. It is a block diagram in the case of doing.
When mixing in a single tank based on the configuration of FIG. 8 (A), the main ash water washing apparatus is configured only from the aeration tank 30b. The fly ash 36 that has been pretreated with water by the sorting device 28 and the pulverizer 29 is put into an aeration tank 30b with a stirrer. The aeration tank 30b is supplied with water 37 for washing. The combustion exhaust gas 55 containing carbon dioxide is blown directly into the aeration tank 30b or into the feed water 37 supplied to the aeration tank 30b, so that water, ash, and carbon dioxide are mixed in the aeration tank 30b. By performing stirring and carbon dioxide aeration in the tank 30b, washing with water and contact between carbon dioxide and ash are realized. The main ash washed with water in the aeration tank 30b is dehydrated by the solid-liquid separator 30c, and the drainage 39 is used by the fly ash washing device 24 as necessary, and a part of the dehydrated ash 30d is converted into a cement / concrete product raw material 38. , A part is again thrown into the aeration tank 30b together with the pretreated main ash.
In addition, when mixing in a plurality of (2) tanks based on the configuration of FIG. 8B, the main ash rinsing apparatus uses a dissolution tank 30e for dissolving carbon dioxide in water, and a solution generated in the dissolution tank as ash. It is composed of two layers of a contact tank 30f to be contacted. The fly ash 36 that has been pretreated with water by the sorting device 28 and the pulverizer 29 is charged into the contact tank 30f. Further, the combustion exhaust gas 55 containing carbon dioxide is introduced into the dissolution tank 30e and mixed with water in the dissolution tank 30e, thereby producing a solution 30g, and unnecessary exhaust gas 30h is discharged. By putting 30 g of the solution into the contact tank 30f, washing with water and contact between carbon dioxide and ash are realized in the contact tank 30f. The main ash washed with water in the contact tank 30f is dehydrated with the solid-liquid separator 30c, and the drainage 39 is used with the fly ash water washing device 24 as necessary. A part is made into a cement / concrete product raw material 38, and a part thereof is again put into the contact tank 30f together with the pretreated main ash.
The single tank is peeled into light ash that is sufficiently mixed by stirring and carbon dioxide aeration, and in the case of such ash, sufficient dissolution and contact with carbon dioxide can be realized even in a single tank. The plurality of tanks are suitable for ash that is heavy and difficult to mix. For example, the efficiency of contact with carbonate ions in which carbon dioxide is dissolved can be increased by circulating wash water through the fixed bed. When gas recovery is necessary, it is advantageous to use a plurality of tanks that can separate the gas flow and the ash slurry flow.

  Moreover, it is suitable to use what combined rough separation and dehydration as a solid-liquid separator shown to 30c. Separation by a sieve or wet cyclone can be used as the rough separation, and a belt-type suction filtration or a drum screen can be used as the dehydration. Since the ash cake after dehydration is originally main ash, there are many gravel-like sharp and hard particles. For this reason, if pressure dehydration, such as a screw press, used for dewatering fly ash and sludge is used, the dehydrator is heavily worn, and filter cloth is easily broken by pressure filtration such as a filter press. Therefore, first, heavy ash is separated from a mixture of light ash and water by rough separation of a sieve or a wet cyclone. The separated heavy ash needs to be dehydrated to remove chlorine and heavy metals in order to obtain a product. For this reason, it is dehydrated by suction filtration or drum screen. Moreover, you may use rinse water for finishing as needed.

FIG. 2 is an overall configuration diagram of the ash treatment according to the second embodiment. The digestion gas 51 generated in the methane fermentation apparatus 50 is blown into the main ash water washing apparatus 30 or the feed water 37 supplied to the main ash water washing apparatus 30. Other configurations were the same as those in Example 1.
In general, most of the components of the digestion gas 51 generated in the methane fermentation apparatus 50 are methane gas, and additionally contain about 30 to 40 vol% of carbon dioxide.

Therefore, by blowing the digestion gas 51 into the main ash water washing apparatus 30 or the feed water 37 supplied to the main ash supply apparatus 30, the amount of elution by carbonation of heavy metals is suppressed and hardly soluble chlorine such as Friedel's salt. The compound can be eluted and the chloride content can be reduced. The eluted slightly soluble chlorine compound is washed away with an ash water washing apparatus. Further, since the carbon dioxide concentration of the digestion gas 51 is higher than that of the combustion exhaust gas 55, a high effect can be expected.
Further, since the digestion gas is recycled as the carbon dioxide supply source, the digestion gas can be effectively used.

Furthermore, after the digestion gas is stored in the gas holder 53, hydrogen sulfide may be removed by a desulfurization device (not shown) and the gas may be used (power generation). In this embodiment, the digestion gas is the main ash washing device 30. Since hydrogen sulfide is removed when it comes into contact with water, desulfurization equipment is not required.
Further, when the gas is used in a combustion apparatus such as a boiler, a gas engine, a gas turbine, etc., a denitration treatment facility is necessary because denitration treatment of thermal NO _x may be required as an exhaust gas treatment after combustion. However, by introducing the exhaust gas into the exhaust gas treatment system of the incinerator and treating it with the exhaust gas of the incinerator, no denitration treatment facility is required.

FIG. 3 is an overall configuration diagram of the ash treatment according to the third embodiment. The digestion gas 51 generated in the methane fermentation apparatus 50, carbon dioxide and concentrated in VPSA apparatus (vacuum regeneration pressure swing device) 56 (CO ₂₎ gas 57 and methane (CH ₄₎ is separated into gas, CO ₂ gas 57 Was blown into the feed water 37 supplied to the main ash water washing apparatus 30 or the main ash supply apparatus 30. Other configurations were the same as those in Example 1.
Generally, the CO ₂ gas obtained by concentrating the digestion gas 51 with the VPSA device 56 has a carbon dioxide concentration of 90% or more.
In this embodiment, a VPSA device (vacuum regeneration pressure swing device) is used to concentrate the digestion gas 51 to obtain carbon dioxide (CO ₂ ) gas. However, the concentration device is not limited to the VPSA device. Any device capable of concentrating digestion gas to obtain carbon dioxide (CO ₂ ) gas may be used.

Therefore, the CO ₂ gas 57 is blown into the main ash water washing device 30 or the feed water 37 supplied to the main ash water washing device 30, thereby suppressing the elution amount by carbonation of heavy metals and hardly soluble such as Friedel's salt. Chlorine compounds can be eluted and the chloride content can be reduced. The eluted slightly soluble chlorine compound is washed away with an ash water washing apparatus. Further, since the carbon dioxide concentration of the CO ₂ gas 57 is higher than that of the combustion exhaust gas 55 and the digestion gas 51, a higher effect can be expected.
Further, since the digestion gas is recycled as the carbon dioxide supply source, the digestion gas can be effectively used.

  FIG. 4 is an overall configuration diagram of the ash treatment according to the fourth embodiment. Usually, since the odor gas 61 generated from the methane fermentation facility 60 including the methane fermentation apparatus 50 contains alkaline substances such as ammonia and hydrogen sulfide, the alkaline substances are removed by acid washing with sulfuric acid or the like in the acid washing tank 62. Further, since acidic substances such as organic acids are further contained, the acidic substances are removed by alkali washing with caustic soda or the like in the alkali washing tank 63, and further activated carbon treatment is performed by the activated carbon treatment device 64 to be released. In this embodiment, the feed water 37 into which the digestion gas 51 has been blown is acidic, so that it can be introduced into the acid cleaning tank 62 as the acid cleaning liquid 65, and the main ash is washed by the main ash water washing apparatus 30. Since it is alkaline, it can be charged into the alkali cleaning tank 63 as an alkaline cleaning liquid 66, and the activated carbon used by the activated carbon treatment device 64 is charged from the waste charging hopper 11 and incinerated in the incinerator 10. did. In addition, in the present embodiment, the other configurations are the same as those of the second embodiment, but at least a part of the digestion gas is blown directly or indirectly into the water supply 37 to the main ash water washing apparatus as a carbon dioxide supply source. Other configurations may be used, for example, the configurations shown in the first and third embodiments, and the configuration is not limited to that of the second embodiment.

In this way, by using the feed water 37 in which the digestion gas 51 is blown into the acid cleaning liquid, and using the waste water after the main ash is washed by the main ash water washing apparatus as the alkaline cleaning liquid, the acid cleaning liquid such as sulfuric acid and the alkaline cleaning liquid such as caustic soda are used. This eliminates the need for external charging and reduces the cost of chemicals. Furthermore, by treating the activated carbon after use with the incinerator 10, the treatment cost of the activated carbon after use can be reduced, and an effect as a combustion aid can be expected.
Therefore, according to this example, it is possible to reduce chloride as in Example 2, and in addition to being able to effectively use digestion gas, it is possible to reduce the cost of the chemical and activated carbon. it can.

  FIG. 5 is an overall configuration diagram of the ash treatment according to the fifth embodiment. In addition to the configuration of the second embodiment shown in FIG. 2, the entire amount of odor gas 61 generated from the methane fermentation facility 60 including the methane fermentation apparatus 50 is introduced together with the primary air 15 from the primary air inlet 13 as part of the combustion air. It was configured as possible. The odor gas 61 is blown together with the primary air 15, is blown together with the secondary air 17, or is blown with the odor of the waste pit to be put into the incinerator 10. It is also possible to use a plurality of blowing methods in combination. In addition, in the present embodiment, the other configurations are the same as those of the second embodiment, but at least a part of the digestion gas is blown directly or indirectly into the water supply 37 to the main ash water washing apparatus as a carbon dioxide supply source. Other configurations may be used, for example, the configurations shown in the first and third embodiments, and the configuration is not limited to that of the second embodiment.

In this way, by blowing the odor gas 61 generated from the methane fermentation facility 60 into the incinerator 10, the treatment facility for the odor gas 61 which has been conventionally required is not required, and the facility can be simplified and the treatment of the odor gas 61 can be performed. The running cost required for the operation of the equipment can also be reduced.
Therefore, according to the present embodiment, the chloride content can be reduced similarly to the second embodiment, the digestion gas can be effectively used, and the processing equipment for the odor gas 61 is not required. Can be simplified and the running cost can be reduced.

FIG. 6 is an overall configuration diagram of the ash treatment according to the sixth embodiment. In addition to the configuration of the second embodiment shown in FIG. 2, the digested sludge 71 generated from the methane fermentation apparatus 50 is input to the incinerator 10 through the waste input hopper 11 and can be incinerated. The digested sludge can be put into the incinerator 10 directly, or mixed with the high calorie waste 31a and then put into the incinerator 10 together with the high calorie waste 31a. It is also possible to use a plurality of charging methods in combination. In addition, in the present embodiment, the other configurations are the same as those in the second embodiment. However, any configuration that allows the digested sludge 71 to be put into the incinerator 10 may be used. However, the present invention is not limited to the configuration of the second embodiment.
In addition, the digested sludge 71 contains water, the amount of moisture brought into the incinerator 10 increases, and if the digested sludge amount is excessive, the temperature in the incinerator 10 may decrease. When dry fermentation having a solid concentration of about 20 to 40% is used as the methane fermentation tank, it is preferable to use dry fermentation because the digested sludge itself has a calorific value capable of self-combustion.

In this way, by introducing the digested sludge 71 into the incinerator 10 and incineration, the processing equipment for the digested sludge 71 can be simplified and the running cost required for the operation of the digested sludge 71 treatment equipment. Can also be reduced.
Therefore, according to the present embodiment, the chloride content can be reduced in the same manner as in Embodiment 2, and in addition to being able to effectively use the digestion gas, there is no need for a treatment facility for digested sludge 71. Can be simplified and the running cost can be reduced.

FIG. 7 is an overall configuration diagram of the ash treatment according to the seventh embodiment. Usually, the digested sludge 71 generated from the methane fermentation apparatus 50 can be composted, carbonized and reused by dehydration. Therefore, the digested sludge 71 is dehydrated by a dehydrator 72, and the dehydrated sludge 73 is dehydrated. Composted and carbonized and reused, and the dehydrated separation liquid is processed in a wastewater treatment facility. In the present embodiment, the dewatering separation liquid 74 generated by dehydrating the digested sludge 71 with the dehydrator 72 is introduced into the incinerator 10 through the waste introduction hopper 11 and incinerated. The dehydration separation liquid 74 may be directly put into the incinerator 10, or mixed with the high calorie waste 31 a and then put into the incinerator 10 together with the high calorie waste 31 a. It is also possible to use a combination of a plurality of input methods. Further, it is preferable to spray the dehydrated separation liquid 74 to the incinerator 10 in order to efficiently perform the incineration process. Other configurations are the same as those in the second embodiment in the present embodiment, but any configuration that allows the dehydration separation liquid 74 to be put into the incinerator 10 is acceptable. However, the present invention is not limited to the configuration of the second embodiment.
Similarly to the sixth embodiment, the dehydration separation liquid 74 contains water, and the amount of water brought into the incinerator 10 increases. When the dehydration separation liquid 74 is excessive, the temperature in the incinerator 10 is increased. Although there is a possibility of lowering, if dry fermentation with a solid concentration of about 20 to 40% is used as a methane fermenter, it is preferable to use dry fermentation because the digested sludge itself has a calorific value that can be combusted. .

Thus, by putting the dehydration separation liquid 74 into the incinerator 10 and performing the incineration treatment, a waste water treatment facility for treating the dehydration separation liquid 74 is not necessary, the equipment can be simplified and the dehydration separation liquid 74 can be processed. The running cost required for the operation of the wastewater treatment facility to be performed can also be reduced. Moreover, the reuse of the dewatered sludge 73 which dehydrated the digested sludge 71 is also possible as usual.
Therefore, according to the present embodiment, the chloride content can be reduced similarly to the second embodiment, and in addition to being able to effectively use the digestion gas, a processing facility for the dehydrated separation liquid 74 is not necessary, Equipment can be simplified and running costs can be reduced, and dewatered sludge 73 can be reused.

  According to the present invention, it is possible to improve the properties at a low cost to less than or equal to the amount that can be efficiently recycled as ash dust, and to effectively utilize the digestion gas generated in the methane fermentation apparatus, and to recycle ash Is promoted.

1 is an overall configuration diagram of ash treatment according to a first embodiment. It is a whole block diagram of the ash process which concerns on the present Example 2. FIG. It is a whole block diagram of the ash processing which concerns on the present Example 3. It is a whole block diagram of the ash processing which concerns on the present Example 4. It is a whole block diagram of the ash processing which concerns on the present Example 5. It is a whole block diagram of the ash process which concerns on the present Example 6. FIG. It is a whole block diagram of the ash processing which concerns on the present Example 7. 8A is a configuration diagram in the case where ash slurry and carbon dioxide (combustion exhaust gas) are mixed in a single tank, and FIG. 8B is a case in which ash slurry and carbon dioxide (combustion exhaust gas) are mixed in a plurality of tanks. It is a block diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Stoker type combustion furnace 11 Waste input hopper 28 Sorting device 29 Pulverizer 30 Main ash water washing device 31a High calorie waste 31b Low calorie waste 33 Fly ash 36 Main ash 37 Water supply 50 Methane fermentation device 51 Digestion gas 54 Combustion device 55 Combustion exhaust gas 56 VPSA equipment 57 CO ₂ gas 60 Methane fermentation equipment 61 Odor gas 65 Acid cleaning liquid 66 Alkaline cleaning liquid 71 Digested sludge 74 Dehydrated separation liquid

Claims (18)

In an ash treatment method for treating ash by injecting carbon dioxide into an ash water washing apparatus for washing ash generated in incineration equipment for incineration of waste and bringing it into contact with ash,
A methane fermentation apparatus for treating waste with methane fermentation is installed in the incineration facility, and at least a part of the digestion gas generated in the methane fermentation apparatus is directly or indirectly introduced into the ash water washing apparatus as a carbon dioxide supply source. An ash treatment method comprising treating ash by contacting the ash.   2. The ash treatment method according to claim 1, wherein at least a part of the combustion exhaust gas combusted with digestion gas generated in the methane fermentation apparatus is indirectly fed into the ash water washing apparatus as a carbon dioxide supply source.   2. The ash treatment method according to claim 1, wherein at least a part of digestion gas generated in the methane fermentation apparatus is directly fed into the ash water washing apparatus as a carbon dioxide supply source.   The ash treatment according to claim 1, wherein at least a part of carbon dioxide gas enriched with carbon dioxide in digestion gas generated in the methane fermentation apparatus is indirectly fed into the ash water washing apparatus as a carbon dioxide supply source. Method.   The ash treatment method according to claim 4, wherein carbon dioxide in the digestion gas generated in the methane fermentation apparatus is concentrated by a VPSA method (vacuum regeneration pressure swing method).   After the odor gas generated in the methane fermentation apparatus has a step of performing acid cleaning, alkali cleaning and activated carbon treatment, using water containing the carbon dioxide as an acid cleaning liquid, and washing with water in the ash water washing apparatus as an alkali cleaning liquid 6. The ash treatment method according to claim 1, wherein the waste activated carbon after use is combusted in an incineration facility using activated carbon treatment.   The ash treatment method according to any one of claims 1 to 5, wherein at least a part of the odor gas generated in the methane fermentation apparatus is blown into an incineration facility for treatment.   The ash treatment method according to any one of claims 1 to 5, wherein the digested sludge generated in the methane fermentation apparatus is incinerated in an incineration facility.   6. A dehydration process for dewatering digested sludge generated in a methane fermentation apparatus, wherein the dewatered separation liquid generated in the dehydration process is put into an incineration facility and incinerated. The ash processing method of crab. In an ash treatment apparatus configured to treat ash by introducing carbon dioxide into an ash water washing apparatus for washing ash generated in incineration equipment for incinerating waste and bringing it into contact with the ash,
A methane fermentation apparatus for treating waste with methane fermentation is installed in the incineration facility, and at least a part of the digestion gas generated in the methane fermentation apparatus is directly or indirectly introduced into the ash water washing apparatus as a carbon dioxide supply source. An ash treatment apparatus configured to treat ash by contacting the ash.   11. The ash treatment apparatus according to claim 10, wherein at least a part of the combustion exhaust gas combusted with the digestion gas generated in the methane fermentation apparatus is indirectly introduced into the ash water washing apparatus as a carbon dioxide supply source. .   The ash treatment apparatus according to claim 10, wherein at least a part of digestion gas generated in the methane fermentation apparatus is directly fed into the ash water washing apparatus as a carbon dioxide supply source.   11. The apparatus according to claim 10, wherein at least a part of carbon dioxide gas enriched with carbon dioxide in digestion gas generated in the methane fermentation apparatus is indirectly introduced into the ash water washing apparatus as a carbon dioxide supply source. The ash treatment apparatus described.   14. The ash treatment apparatus according to claim 13, wherein carbon dioxide in digestion gas generated in the methane fermentation apparatus is configured to be concentrated by a VPSA method (vacuum regeneration pressure swing method).   After having the means to perform acid cleaning, alkali cleaning and activated carbon treatment of the odor gas generated in the methane fermentation apparatus, using the water containing the carbon dioxide as the acid cleaning liquid, after washing in the ash water washing apparatus as the alkaline cleaning liquid The ash treatment apparatus according to any one of claims 10 to 14, wherein the waste activated carbon used in the activated carbon treatment is combusted in an incineration facility using the waste water.   The ash treatment apparatus according to any one of claims 10 to 14, wherein at least a part of the odor gas generated in the methane fermentation apparatus is blown into an incineration facility for treatment.   The ash treatment apparatus according to any one of claims 10 to 14, wherein the digested sludge generated in the methane fermentation apparatus is incinerated in an incineration facility. It has a dehydration means which carries out the dehydration process of the digested sludge generated in the methane fermentation apparatus, and incinerates the dehydration separation liquid generated by the dehydration means in incineration equipment. The ash treatment apparatus described.

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