JP2015054313A - Processing method of incineration ash and incineration apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method of incineration ash capable of further making dioxin harmless while simultaneously and stably making lead and hexavalent chromium harmless in heavy metals contained in the incineration ash and to provide an incineration apparatus capable of performing the processing method.SOLUTION: An exhaust gas being exhausted from a gas engine where a hydrocarbon-mixed gas whose main component is methane is a fuel and containing carbon dioxide of 5-15 vol% and oxygen of 5-15 vol% is brought into direct contact with the incineration ash at 300-400°C in the absence of the exhaust gas of an incineration furnace and aging is performed for 30-60 minutes when the incineration ash from the waste incineration furnace is processed to be harmless. Lead and hexavalent chromium contained in the incineration ash are made harmless and a PCDF component contained as dioxins is reduced.

Description

  The present invention relates to an incineration ash treatment method and incineration equipment for detoxifying incineration ash from a waste incinerator.

Incineration ash is a method for insolubilizing heavy metals such as lead and hexavalent chromium contained in incineration ash in order to make effective use of incineration ash discharged from waste incinerators that incinerate municipal waste. An aging treatment is known in which carbon dioxide is brought into contact with each other to render it harmless (see, for example, Patent Document 1).
When actually carrying out the aging treatment, conventionally, the incineration ash from the waste incinerator is aged by contacting the exhaust gas containing carbon dioxide discharged from the waste incinerator, and thereby included in the incineration ash. A treatment method for incineration ash that renders lead or the like harmless and a treatment apparatus for carrying out the treatment method have been proposed (see, for example, Patent Documents 2 and 3).

JP 2002-18392 A JP 2003-126807 A JP 2006-281150 A

However, in the methods and apparatuses described in Patent Documents 2 and 3, since the exhaust gas discharged from the waste incinerator is used as the exhaust gas containing carbon dioxide, it is impossible to always perform stable aging treatment. was there.
In other words, the waste incinerator is for incinerating city garbage, etc. consisting of various kinds of garbage, such as raw garbage and waste plastic. For example, if there is a large amount of garbage in the city garbage If the moisture content increases, the thermal energy per unit weight decreases, and if a large amount of waste plastic or the like is contained, the thermal energy per unit weight increases. As a result, not only the temperature of the exhaust gas greatly varies, but also the concentrations of carbon dioxide, oxygen, etc. contained in the exhaust gas greatly vary depending on the type of garbage.
Therefore, in the methods and apparatuses described in Patent Documents 2 and 3, the temperature of the exhaust gas used for the aging treatment or the concentration of carbon dioxide contained in the exhaust gas greatly fluctuates, and stable aging treatment cannot be performed. As a result, there was a problem that lead and hexavalent chromium contained in incineration ash could not be stably rendered harmless.

  Further, it is generally known that dioxins are generated when waste is incinerated, and it is desired to make the dioxins harmless. By the way, about the fly ash which generate | occur | produces when a waste is incinerated, the removal method of a dioxin is researched. Various components contained in the incinerated waste are contained as harmful components in the exhaust gas. Especially, the combustion exhaust gas of chlorinated resin waste such as vinyl chloride contains chlorine-containing gas such as hydrogen chloride. It is. The chlorine-containing gas is known to synthesize dioxins at 250 ° C to 400 ° C.

  From the above situation, it is clear that incineration ash also contains dioxin, but when incineration ash is aged using the above exhaust gas, dioxin may be re-synthesized in the incineration ash and incineration It is considered that dioxins in ash cannot be sufficiently detoxified.

  The present invention pays attention to such a conventional problem, and the purpose thereof is to simultaneously detoxify dioxins while stably detoxifying lead and hexavalent chromium among heavy metals contained in incinerated ash. An incineration ash treatment method that can be performed and an incineration facility capable of performing the treatment method are provided.

[Configuration 1]
In order to achieve the above object, the characteristic configuration of the incineration ash treatment method of the present invention is:
In order to detoxify the incineration ash from the waste incinerator,
An exhaust gas containing 5 to 15% by volume of carbon dioxide and 5 to 15% by volume of oxygen, which is an exhaust gas from a gas engine fueled with a hydrocarbon mixed gas mainly composed of methane, with respect to the incineration ash In the absence of incinerator exhaust gas, direct contact at 300 to 400 ° C. and aging for 30 to 60 minutes to detoxify lead and hexavalent chromium contained in the incinerated ash, and PCDF contained as dioxins The point is to reduce the components.

[Operation effect 1]
Exhaust gas from a gas engine fueled with a hydrocarbon mixed gas containing methane as a main component does not basically contain a chlorine component, contains 5 to 15% by volume of carbon dioxide, and contains 15% by volume or less of oxygen. That is, as will be described later, as a result of investigating a gas engine that is actually operating over a long period of time, the exhaust gas from the gas engine contains 5 to 15% by volume of carbon dioxide and 5 to 15% by volume of oxygen. It has been found that the exhaust gas is contained, and it has been confirmed that the fluctuation range of the carbon dioxide concentration and the oxygen concentration is much smaller than that of the exhaust gas from the waste incinerator. When such an exhaust gas is used and an aging treatment is performed in the absence of the incinerator exhaust gas, there is no chlorine supply from the incinerator exhaust gas, and therefore the aging treatment can be performed without concern about the resynthesis of dioxins from the exhaust gas.

According to the above configuration, as is apparent from the experimental results to be described later, the contents of lead and hexavalent chromium are suppressed, and can be rendered harmless before the standard of Environmental Agency Notification No. 19 is achieved.
Furthermore, instead of the exhaust gas from the conventional waste incinerator, it is provided in a gas engine using a hydrocarbon mixed gas mainly composed of methane as a fuel, for example, a cogeneration facility for supplying heat and electric power to a factory, for example. Since exhaust gas from the gas engine is used, the exhaust gas discharged from the gas engine of the cogeneration facility will be used effectively, and the amount of lead and hexavalent chromium that will be dissolved will reach the standard of Environment Agency Notification No. 46. It can be rendered harmless.
The exhaust gas from the gas engine has a much smaller variation range in all of the exhaust gas temperature, carbon dioxide concentration, and oxygen concentration compared to the exhaust gas from the waste incinerator. Chromium can be made stable and harmless at the same time.

  By the way, as dioxin detoxification technology for incineration fly ash, generally, since dioxin is re-synthesized at 250 ° C. to 400 ° C., it is customary to set the detoxification temperature range to a temperature exceeding 400 ° C. And there was a fixed idea that such a temperature range should be maintained even when incineration ash is rendered harmless. However, in the incineration fly ash and incineration ash treatment environment, the incineration fly ash treatment environment is detoxified in the process of lowering the temperature after being heated to a high temperature in the air stream, whereas incineration ash There is a difference that detoxification treatment is performed in the process of heating while cooling the fine particles that have been cooled. Therefore, the present inventors examined the incineration ash detoxification test in view of whether the above fixed concept should be applied as it is in detoxifying incineration ash.When detoxifying dioxins in incineration ash, Surprisingly, the PCDF component, which is abundant in dioxins, is reduced even in the temperature range of 300 ° C to 400 ° C, which is the temperature range where dioxins are originally synthesized, under the conditions that lead and hexavalent chromium are rendered harmless. I found out that I can make it.

According to the above-mentioned new knowledge, it is clear that it is not necessary to treat incinerated ash with dioxin, so it is not necessary to perform treatment in a high temperature range, which has been considered in the past. I understood.
Dioxins contain components such as PCDD (polychlorinated dibenzodioxin), PCDF (polychlorinated dibenzofuran), and PCB (polychlorinated biphenyl). However, according to this treatment method, a large amount of PCDF is contained. Since the detoxification efficiency of the components is high, and it contributes to the reduction of particularly toxic components, the rate of TEQ reduction is higher than the detoxification efficiency evaluated from the decrease in the total amount of dioxins, and the detoxification efficiency is extremely high It is thought that it can be evaluated as a thing.

[Configuration 2]
In order to achieve the above object, the characteristic configuration of the incineration facility of the present invention is:
An incineration facility comprising a waste incinerator and a gas engine power generator, wherein at least a part of the power required in the waste incinerator is covered by power generated by the gas engine power generator;
An aging process having an incineration ash charging unit for charging the incinerated ash from the waste incinerator and an exhaust gas introducing unit for introducing the exhaust gas from the gas engine power generation apparatus, and an exhaust unit for extracting the aged incineration ash It is in the point provided with the incineration ash processing apparatus which provides a part.

[Operation effect 2]
Conventionally, when making incineration ash harmless, it was necessary to collect the incineration ash once from the incineration facility, and then transport it to the detoxification facility to process it separately. In particular, there are few known equipments that can stably obtain gas engine exhaust gas as described above adjacent to the waste incinerator. There is no known existing treatment facility that can supply both ash and gas engine exhaust.

  By the way, in recent years, an increasing number of cases in which various facilities with incidental power generation facilities are employed. There are also several incinerators with power generation facilities all over the country. Although such power generation facilities are for disasters, there is a movement to drive in order to use them effectively during normal times. There is also a movement to add power generation facilities for disasters. As a result, at least a part of the electric power required in the waste incinerator can be covered by the electric power generated by the gas engine power generation device, and the incineration facility can be operated more stably. . In such an incineration facility, the incineration ash generated from the waste incinerator and the exhaust gas from the gas engine fueled with the hydrocarbon mixed gas generated from the power generation device contains 5 to 15% by volume of carbon dioxide, If an incineration ash treatment apparatus having an incineration ash input section and an exhaust gas introduction section for supplying exhaust gas containing 5 to 15% by volume of oxygen to the aging treatment section is provided, a waste incinerator and a gas engine power generation apparatus are provided. The incineration ash can be aged by effectively cooperating, and the aged incineration ash can be obtained from the discharge unit.

  As a result, incineration ash that conventionally had to be separately aged can be efficiently aged on the spot. Therefore, an incineration ash treatment device is additionally provided in the incineration facility, and the existing gas engine power generation device or the like is effectively used, so that the waste treatment cost can be reduced with a small capital investment.

  Also, if it is not aged, it has no utility value, and even if it is aged with a great deal of labor, if the degree of detoxification is low, incineration ash that has a low utility value is combined with exhaust gas that is simply discarded In addition, the incineration ash can be aged to a reusable form, and waste can be effectively used. That is, in such an incineration facility, since the incineration ash treatment method described above can be performed efficiently, incineration ash with reduced toxicity of dioxin and reduced toxicity of lead and hexavalent chromium can be obtained. Can be reused as soil, or depending on the degree of processing, at least landfill processing can be performed, and utility value can be generated.

  In addition, according to the said structure, an incineration equipment can always maintain an operation state by self-power generation not only at the time of a disaster. Moreover, the waste heat from the waste incinerator and the gas power generation device can be used for heating the incineration ash, and the energy can be used effectively. Furthermore, since the operating temperature of the incineration ash treatment apparatus does not need to be raised to 400 ° C. or higher, which has been conventionally considered, there is an effect of suppressing running cost as compared with the conventional case.

  Therefore, among heavy metals contained in incineration ash, lead and hexavalent chromium can be made stable and harmless at the same time, while dioxins can be made harmless, and incineration ash can be processed efficiently and used effectively. It became possible to convert to a different form.

Schematic configuration diagram showing incineration equipment

Embodiments of an incineration ash treatment method and incineration equipment according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, the incineration facility according to the present invention includes a waste incinerator 1 and a gas engine power generation device 5, and includes an incineration ash treatment device 6. The incineration facility covers at least a part of the electric power necessary for the waste incinerator 1 with the electric power generated by the gas engine power generation device 5, the incineration ash generated from the waste incinerator 1, and the gas engine 52. By supplying both the exhaust gas from the incineration ash treatment device 6, the incineration ash is disposed so as to be efficiently detoxified.

  The incineration ash treatment apparatus 6 detoxifies the incineration ash discharged from the waste incinerator 1 for incinerating waste such as municipal waste, that is, incineration ash containing lead and hexavalent chromium and containing dioxin. A rotary kiln device 60 (one form of aging treatment unit), a dryer 2 for drying the incineration ash discharged from the waste incinerator 1, a classification device 3 for removing foreign matter from the dried incineration ash, and classification A hopper 4 (one form of the incineration ash charging unit) that stores the used incineration ash and supplies it to the rotary kiln device 60 is provided. On the other hand, the gas engine power generator 5 uses a hydrocarbon mixed gas mainly composed of methane as a fuel, the gas engine 52 that drives the power generator 51, and the incinerated ash supplied from the hopper 4, which is discharged from the gas engine 52. The rotary kiln device 60 is provided for aging by contacting the exhaust gas.

  The incineration ash treatment device 6 includes a rotary kiln device 60, an exhaust gas temperature maintaining mechanism 7 for maintaining the inside of the rotary kiln device 60 at 300 to 400 ° C. with exhaust gas, and the like. The rotary kiln device 60 takes out the incineration ash input part 61 for introducing the incineration ash from the waste incinerator 1, the exhaust gas introduction part 62 for introducing the exhaust gas discharged from the gas engine 52, and the aged incineration ash. A discharge part 63 is provided.

The incineration ash discharged from the waste incinerator 1 is dried by the dryer 2. The dried incineration ash is removed by the classifier 3 together with foreign matters (dry batteries, etc.) together with difficult-to-treat materials exceeding a diameter of 38 mm, supplied to the rotary kiln device 60, and aged by contact with the exhaust gas from the gas engine 52. Is done.
The gas engine power generation device 5 uses a hydrocarbon mixed gas mainly composed of methane as a fuel, for example, plays a part of cogeneration equipment that can supply heat and power that are separately in demand. By operating with a thin air-fuel mixture (for example, with an air ratio of about 1.6 to 2.1), the engine is operated in a lean burn state with high fuel efficiency.

Regarding the exhaust gas from the gas engine 52, as a result of investigating about four gas engines 52 actually operated over almost one to two years, it contains 5 to 15% by volume of carbon dioxide and 5 to 15% of oxygen. % Content was confirmed. Further, the temperature of the exhaust gas is about 400 to 600 ° C., and the fluctuation range is much smaller than the exhaust gas from the waste incinerator 1 in all of the exhaust gas temperature, carbon dioxide concentration, and oxygen concentration. confirmed.
The exhaust gas temperature maintaining mechanism 7 adjusts the temperature of the exhaust gas and maintains the inside of the rotary kiln device 60 at 300 to 400 ° C. with the exhaust gas. Specifically, the exhaust gas discharged from the gas engine 52 is sent to the rotary kiln device 60. It is composed of exhaust gas supply pipes for supply (that is, the rotary kiln device 60 performs aging treatment in the absence of incinerator exhaust gas), and gas is supplied through the exhaust gas supply pipes functioning as the exhaust gas temperature maintenance mechanism 7. Exhaust gas from the engine 52 is supplied to the rotary kiln device 60.
However, in some cases, the exhaust gas temperature maintenance mechanism 7 is configured by a temperature adjustment mechanism that actively heats or cools the exhaust gas temperature, and the exhaust gas temperature maintenance mechanism 7 is interposed in the exhaust gas supply pipe. You can also.

The rotary kiln device 60 is provided with a large number of stirring blades that are inclined so that the upstream side (left side of the drawing) is high and the downstream side (right side of the drawing) is low, and rotates inside, and is supplied from the hopper 4. The incinerated ash is moved and conveyed from the upstream side toward the downstream side as indicated by the solid line in the figure.
On the other hand, the exhaust gas from the gas engine 52 is supplied from the downstream side, and reversely flows from the downstream side to the upstream side, as shown by the broken line in the figure, and is opposed to the incineration ash, and by the stirring blade. Aging is achieved by direct contact between the exhaust gas and the incinerated ash by a stirring action.
The incinerated ash that has been rendered harmless by aging is stored in the treated hopper 8, and the exhaust gas that has been subjected to aging is cooled by the cooling tower 91 and collected by the dust collector 92, and then outside the apparatus. Is exhausted.

  Next, the operation of the incineration ash treatment apparatus 6 according to the present invention will be described, and a method for treating the incineration ash carried out using the incineration ash treatment apparatus 6 will be mentioned.

(Lead and hexavalent chromium)
The incinerated ash discharged from the waste incinerator 1 is dried by the drier 2, and then a difficult-to-process product exceeding a diameter of 38 mm is removed together with foreign substances by the classifier 3 and stored in the hopper 4. That is, the classification process is performed by the classification device 3.
The classified incineration ash that has passed through the classification process is supplied to the rotary kiln device 60, and in the rotary kiln device 60, the classified incineration ash that moves from the upstream side to the downstream side is circulated from the downstream side to the upstream side. An aging treatment step is performed in which the exhaust gas from the gas engine 52 is abutted at 300 to 400 ° C. and aged for 30 to 60 minutes. As a result, lead and hexavalent chromium contained in the incineration ash are rendered harmless and treated hopper 8 is sent.

  The incineration ash treatment method and treatment apparatus according to the present invention detoxifies lead and hexavalent chromium contained in the incineration ash, and the Environment Agency Notification No. 19 (content test: lead = 150 mg / kg or less, hexavalent chromium = 250 mg). / Kg or less) and Environmental Agency Notification No. 46 (elution amount test: lead = 0.01 mg / L or less, hexavalent chromium = 0.05 mg / L or less) at the same time, Various experiments were conducted to confirm the effect, and a part of the experimental results will be described.

  Table 1 shows the content and elution amount of lead and hexavalent chromium from the incinerated ash subjected to the aging treatment by the above-mentioned process according to the notification of each environmental agency.

  In addition, both the raw materials 1 and 2 are dry ash obtained by melting and pulverizing the bottom ash of the waste incinerator 1, and the samples are aligned to a diameter of 38 mm or less through the above classification step. No. 2 was used after passing through the above aging process and excluding fine particle components having a diameter of 5 mm or less and having a diameter of 5 to 38 mm.

It can be confirmed that the content of lead in the incinerated ash satisfies the standard of Environmental Agency Notification No. 19 (lead = 150 mg / kg or less).
As a result, it can be confirmed that the standard (lead = 0.01 mg / L or less) of the Environment Agency Notification No. 46 is achieved by aging the incinerated ash with respect to the lead elution amount.
The content of hexavalent chromium is less than 10 mg / kg in all cases, and the standard of the Environment Agency Notification No. 19 (hexavalent chromium = 250 mg / kg or less) is achieved.

  The above is a part of the experimental results. In addition, exhaust gas when the gas engine 52 is operated in a lean burn state by an elution amount experiment using incinerated ash (carbon dioxide = 5% by volume, oxygen = 10% by volume). As a result of adjusting the temperature of the exhaust gas to four stages of 200 ° C., 300 ° C., 400 ° C., and 500 ° C. and performing aging for two stages of 30 minutes and 60 minutes, any temperature was obtained. As a result, the lead elution amount was less than 0.005 mg / L and the hexavalent chromium elution amount was less than 0.01 mg / L.

(Dioxin)
The raw material 1 was used as a sample, the aging process was performed in the same manner, and the dioxin amount was measured in accordance with Ministry of the Environment Notification No. 80. As the dioxin amount, the toxic equivalent amount (TEQ) was determined according to the toxic equivalent coefficient (TEF) shown in WHO / IPCS (2006).

  As a result, as shown in Table 2, when the aging process at 400 ° C. is performed, it is clear that PCDF, which is particularly abundant in dioxins, is greatly reduced, contributing to a decrease in TEQ. It was.

In the above measurement test, the aging process at an aging temperature of 400 ° C. was examined, but it was confirmed that the same tendency was observed even if the aging conditions were slightly low, and if the aging temperature was 300 ° C. or higher, It is clear that a similar effect can be expected. That is, by setting the aging temperature to 300 ° C. to 400 ° C., in the aging atmosphere of the incineration ash, the dioxin reconstituted, which has been conventionally established, is not performed unexpectedly, and the dioxin reduction effect contained in the incineration ash is reduced. I found out that I can demonstrate it. Further, according to this test, TCDF as the main component of the TEQ component contained in the incinerated ash was extremely efficiently reduced, and thus it was found that the test method was particularly useful as a treatment method for the incinerated ash.
In addition, although the aging time is set to 60 minutes, in view of the TEQ reduction effect of the measurement test, it is expected that the dioxin reduction effect is sufficiently exhibited even with the aging time of 30 minutes.

1 Waste incinerator 3 Classification device 5 Gas engine 6 Rotary kiln device 7 Exhaust gas temperature maintenance mechanism

Claims (2)

An incineration ash treatment method for detoxifying incineration ash from a waste incinerator,
An exhaust gas containing 5 to 15% by volume of carbon dioxide and 5 to 15% by volume of oxygen, which is an exhaust gas from a gas engine fueled with a hydrocarbon mixed gas mainly composed of methane, with respect to the incineration ash In the absence of incinerator exhaust gas, direct contact at 300 to 400 ° C. and aging for 30 to 60 minutes to detoxify lead and hexavalent chromium contained in the incinerated ash, and PCDF contained as dioxins Incineration ash treatment method to reduce components. An incineration facility comprising a waste incinerator and a gas engine power generator, wherein at least a part of the power required in the waste incinerator is covered by power generated by the gas engine power generator;
An aging process having an incineration ash charging unit for charging the incinerated ash from the waste incinerator and an exhaust gas introducing unit for introducing the exhaust gas from the gas engine power generation apparatus, and an exhaust unit for extracting the aged incineration ash An incineration facility equipped with an incineration ash treatment device.

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