JP5774869B2 - Incineration ash treatment method and equipment - Google Patents

Description

  The present invention relates to a method for treating incineration ash by reacting incineration ash from a waste incinerator with an apparatus that efficiently reacts incineration ash from waste gas containing carbon dioxide gas (hereinafter referred to as “reaction apparatus”), The present invention relates to incineration ash treatment equipment for carrying out the treatment method.

In order to effectively use incineration ash discharged from waste incinerators that incinerate municipal waste, incineration ash and carbon dioxide gas are used as a method of insolubilizing heavy metals such as lead contained in incineration ash to make them harmless. An aging treatment is known in which the contained exhaust gas is reacted with a reactor to render it harmless.
Conventionally, when carrying out such an aging treatment, the exhaust gas discharged from the waste incinerator is supplied to the reactor, and the carbon dioxide contained in the exhaust gas from the waste incinerator and the incineration ash are reacted in the reactor. Thus, a treatment method for incineration ash that renders heavy metals such as lead contained in the incineration ash harmless and a treatment facility for carrying out the treatment method have been proposed (for example, see Patent Documents 1 and 2).

JP 2003-126807 A JP 2006-281150 A

However, in the method and equipment described in the above-mentioned patent document, since exhaust gas discharged from a waste incinerator is used as exhaust gas containing carbon dioxide, it is difficult to always perform stable aging treatment. It was.
In other words, a waste incinerator is for incinerating municipal waste, for example. If a large amount of raw garbage is contained in the municipal waste, the amount of moisture increases and the heat per unit weight is increased. If the energy decreases and a large amount of waste plastic is contained, the thermal energy per unit weight increases, and as a result, the temperature of the exhaust gas fluctuates greatly and stable aging is performed. It becomes difficult.
Furthermore, in addition to such fluctuations in exhaust gas temperature due to waste quality, the oxygen concentration and carbon dioxide concentration contained in the exhaust gas also vary greatly depending on the waste quality, so the aging treatment is not stable and heavy metals contained in incineration ash There was a problem that could not be stably rendered harmless.

  The present invention pays attention to such conventional problems and also pays attention to the fact that incineration ash discharged from a waste incinerator may contain chromium in addition to lead. An object is to provide a processing method and processing equipment for incineration ash that can stably detoxify, for example, lead and hexavalent chromium among the heavy metals contained in the incineration ash simultaneously with simple equipment.

In order to achieve the above object, the characteristic configuration of the incineration ash treatment method of treating the incineration ash by reacting the incineration ash from the waste incinerator according to the present invention with the exhaust gas containing carbon dioxide gas in a reactor,
Engine exhaust gas in a range of 340 ° C. to 500 ° C. from a gas engine operated using hydrocarbons as fuel is supplied to the reactor, and carbon dioxide in the engine exhaust gas is reacted with the incineration ash for a predetermined processing time. The lead and hexavalent chromium contained in the incinerated ash are made harmless.

That is, as exhaust gas containing carbon dioxide gas, instead of exhaust gas from a conventional waste incinerator, engine exhaust gas from a gas engine using hydrocarbon as fuel is used, so heat and power are supplied to a factory, for example. Engine exhaust gas from a gas engine provided in a cogeneration facility can be used.
The temperature of the engine exhaust gas from the gas engine falls within the range of about 340 ° C. to 500 ° C., as will be apparent from the data to be described later, and is about 8.8 to 11.8% by volume in the engine exhaust gas. In a lean burn state in which 5.2 to 6.7% by volume of carbon dioxide gas is contained, and in a stoichiometric state in which oxygen is not contained and 9.0 to 11.0% by volume of carbon dioxide gas is contained Compared to the exhaust gas from the waste incinerator, the fluctuation range is much smaller in all of the exhaust gas temperature, oxygen concentration, and carbon dioxide concentration.

As a result of various experiments conducted by the present inventors based on the properties of the engine exhaust gas, as will be apparent from the experimental results described later, the gas engine operated from hydrocarbons as a fuel operates at 340 ° C to 500 ° C. Detoxify lead and hexavalent chromium contained in incineration ash by using engine exhaust gas in the range of ℃ and reacting carbon dioxide in the engine exhaust gas with incineration ash for a predetermined treatment time. It came to know that is possible.
Therefore, for example, engine exhaust gas from a gas engine provided in a cogeneration facility can be effectively used to stably detoxify lead and hexavalent chromium contained in incineration ash with simple equipment.

In the incineration ash treatment method having the above characteristic configuration, the exhaust gas from the gas engine is preferably engine exhaust gas in a range of 340 ° C. to 490 ° C. operated in a lean burn state.
By using engine exhaust gas in the range of 340 ° C. to 490 ° C. operated in the lean burn state as described above, the elution concentration of at least hexavalent chromium is determined based on the soil environment standard, as will be apparent from the later experimental results. As a result, while reducing fuel consumption, the engine exhaust gas from the gas engine that is operated in lean burn state, which enables rated operation with high efficiency, is used, and is contained in the incineration ash. Valuable chromium can be rendered harmless.

Further, in the incineration ash treatment method having the above-described characteristic configuration, the exhaust gas from the gas engine is preferably engine exhaust gas in a range of 350 ° C. to 500 ° C. operated in a stoichiometric state.
By using engine exhaust gas in the range of 350 ° C. to 500 ° C. operated in a stoichiometric state as described above, the elution concentration of both lead and hexavalent chromium can be determined for the soil environment, as is apparent from the results of later experiments. It becomes possible to keep it below the reference value.

In the above description, the incineration ash processing method according to the present invention has been described. However, the incineration ash processing facility according to the present invention can achieve the object of the present invention by adopting the following configuration.
That is, in order to configure the incineration ash treatment equipment for treating the incineration ash by reacting the incineration ash from the waste incinerator with the exhaust gas containing carbon dioxide gas in the reactor,
By providing a gas supply path for supplying the engine exhaust gas from the gas engine to the reactor into which the incinerated ash containing lead and hexavalent chromium is introduced, the gas engine that has been described so far is provided. In addition, lead and hexavalent chromium contained in incineration ash can be stably rendered harmless.

Schematic diagram of incineration ash treatment equipment Schematic diagram of the equipment used in the experiment Figure showing composition fluctuation value of exhaust gas from waste incinerator and gas engine Graph showing the amount of lead elution during lean burn operation by experiment Graph showing the elution amount of chromium (hexavalent chromium) during lean burn operation by experiment Graph showing the amount of lead elution during stoichiometric operation Graph showing the elution amount of chromium (hexavalent chromium) during stoichiometric operation by experiment

Embodiments of a method and a treatment facility for incineration ash according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, the incineration ash treatment facility according to the present invention includes a waste incinerator 1 for incinerating waste such as municipal waste, and incineration ash discharged from the waste incinerator 1, that is, lead and six Hydrocarbon for power generation at the time of start-up operation and emergency power generation of the waste incinerator 1 by reacting the incineration ash containing valent chromium with the exhaust gas containing carbon dioxide gas The gas engine 3 is operated in a lean burn state using as a fuel, and is also operated in a stoichiometric state using hydrocarbons as a fuel, and the reactor exhaust gas in the range of 340 ° C. to 500 ° C. discharged from the gas engine 3 2 is provided with a gas supply path 4 to be supplied to 2.

For example, the gas engine 3 serves as a corner of a cogeneration facility that can supply heat and electric power that are separately demanded in parallel, and is a mixture that is thinner than the theoretical air ratio (air ratio 1.6-2. 1), the engine is operated in a lean burn state with high fuel efficiency, and is substantially operated with an air-fuel mixture with a theoretical air ratio (air ratio of about 0.95 to 1.05). As a result, the heat and power generated in the stoichiometric state and generated in the cogeneration facility are used in a factory where the facility is installed.
The incinerated ash discharged from the waste incinerator 1 is introduced into the reactor 2 as indicated by the arrow, and the engine exhaust gas from the gas engine 3 operated in the lean burn state or stoichiometric state is supplied to the gas supply path. The lead and hexavalent chromium contained in the incineration ash are fed to the reactor 2 through 4 and reacted with carbon dioxide contained in the engine exhaust gas for a predetermined treatment time to be detoxified after detoxification. Taken out as ash.

The exhaust gas after the aging treatment in the reactor 2 is released to the atmosphere through the exhaust gas discharge path 5, and when the reactor 2 does not require engine exhaust gas, the engine exhaust gas from the gas engine 3 passes through the engine exhaust gas discharge path 6. Through the atmosphere.
For this reason, a switching damper 7 is provided at a connection point between the gas supply path 4 and the engine exhaust gas discharge path 6, and a control device 8 for controlling the switching damper 7 is provided so that the engine exhaust gas from the gas engine 3 is Switching between a state of being supplied to the reactor 2 via the gas supply path 4 and a state of being released to the atmosphere via the engine exhaust gas discharge path 6 is possible.

Next, the present inventors investigated the property (composition variation value) of engine exhaust gas discharged from a gas engine operated in a lean burn state or stoichiometric state using hydrocarbons as a fuel over a long period of time, and the outlet of the waste incinerator The result is shown in FIG.
The gas engines A, B, and C shown in FIG. 3 are in a lean burn state, and the gas engine D is in a stoichiometric state, each of which is actually operating four gas engines. About these four gas engines, This is the result of investigation over almost one to two years.
Referring to FIG. 3, the exhaust gas from the waste incinerator has relatively large fluctuations in all of its oxygen concentration (volume%), carbon dioxide concentration (volume%), and exhaust gas temperature (° C.). On the other hand, the engine exhaust gas from the gas engine operated in the lean burn state or the stoichiometric state has a relatively small variation in the four engines A, B, C, and D, and is very stable. Also in the gas engine D operated in the state, the fluctuation range of the oxygen concentration, the carbon dioxide concentration, and the exhaust gas temperature is small as compared with the case of the waste incinerator.

Moreover, since the present inventors conducted the experiment for confirming the reaction condition of the incineration ash containing lead and hexavalent chromium and the engine exhaust gas from the gas engine, the experimental result will be described.
As shown in FIG. 2, the apparatus used in the experiment was bubbled in a gas cylinder 10 for supplying engine exhaust gas from a gas engine operated in a lean burn state or stoichiometric state using hydrocarbons as a fuel, a flow meter 11, and hot water. The hot water tank 12 for making the water content equal to that of the actual engine exhaust gas, and the gas heating unit 13 for preheating the engine exhaust gas from the hot water tank 12 are connected as shown in FIG. The engine exhaust gas is configured to be supplied to the reaction device (aging furnace) 2. In the reaction device 2, the incinerated ash and the engine exhaust gas are reacted while being stirred at 30 rpm by a stirrer.

Regarding the elution of lead, 200 g of incinerated ash containing 0.1 mg / L (initial value) of lead is introduced into the reactor 2, and in the lean burn state, engine exhaust gas containing 10% oxygen and 5% carbon dioxide is used. In the stoichiometric state, engine exhaust gas containing 0% oxygen and 10% carbon dioxide gas was supplied from the gas cylinder 10 at a flow rate of 11 L / min for 30 minutes and 60 minutes, respectively.
Then, the aging treatment is performed by changing the temperature of the engine exhaust gas by 50 ° C. by the gas heating unit 13 in the range of 300 ° C. to 500 ° C. in the lean burn state and in the range of 350 ° C. to 500 ° C. in the stoichiometric state. The incinerated ash after treatment was measured for the amount of lead elution based on the Environment Agency Notification No. 46 dissolution test.

The result in the lean burn state is shown in FIG. 4. From this experimental result, the lead elution amount in the lean burn state is obtained when the exhaust gas temperature is 410 when the aging treatment is performed for 30 minutes (indicated by the dotted line in the figure). If it is ℃ or more, it can be suppressed to 0.01 mg / L or less of the soil environment standard value, and when performing the aging treatment for 60 minutes (shown by the solid line in the figure), the soil environment standard value is 340 ° C or more. It can be seen that the following can be suppressed.
In addition, the result in the stoichiometric state is shown in FIG. 6 (the aging process time is almost overlapped between 30 minutes and 60 minutes, and is shown by a single solid line). In the state, regardless of the aging treatment time, that is, for 30 minutes or 60 minutes, if the exhaust gas temperature is in the range of 350 ° C. to 500 ° C., keep it below the soil environment standard value. Is understood to be possible.

  As for the elution of chromium, 200 g of incinerated ash containing 0.04 mg / L (initial value) of lead is introduced into the aging device 2, and in the lean burn state, engine exhaust gas containing 10% oxygen and 5% carbon dioxide is used. In the stoichiometric state, engine exhaust gas containing 0% oxygen and 10% carbon dioxide gas is supplied from the gas cylinder 10 at a flow rate of 11 L / min for 30 minutes and 60 minutes, respectively, and the temperature of the engine exhaust gas is made lean as in the case of lead. Aging is carried out by changing the temperature in the range of 300 ° C to 500 ° C in the burned state and in the range of 350 ° C to 500 ° C in the stoichiometric state by 50 ° C, respectively. Based on the dissolution test, the dissolution amount of hexavalent chromium was measured.

FIG. 5 shows the result in the lean burn state, and the elution amount of hexavalent chromium in the lean burn state is when the aging treatment is performed for 30 minutes (indicated by a dotted line in the figure), the exhaust gas temperature is 300 ° C. to 500 ° C. In the entire range of ℃, it is possible to suppress the soil environment standard value to 0.05 mg / L or less, and when aging treatment is performed for 60 minutes (shown by the solid line in the figure), the soil environment standard value is 490 ℃ or less. It can be seen that the following can be suppressed.
Further, the result in the stoichiometric state is shown in FIG. 7 (the aging processing time is almost overlapped between 30 minutes and 60 minutes, and is shown by a single solid line). In the state, as in the case of lead, even if the aging treatment time is 30 minutes or 60 minutes, if the exhaust gas temperature is in the range of 350 ° C. to 500 ° C., keep it below the soil environment standard value. Is understood to be possible.

From the above results, when using engine exhaust gas in the lean burn state, lead is suppressed to below the soil environmental standard value at an exhaust gas temperature of 340 ° C or higher by performing an aging treatment for 60 minutes. As for hexavalent chromium, it has been found that even when aging treatment is performed for 60 minutes, the exhaust gas temperature is 490 ° C. or less and the amount of elution can be suppressed to a soil environment standard value or less.
Therefore, engine exhaust gas in a range of 340 ° C. to 490 ° C. from a gas engine operated in a lean burn state using hydrocarbons as fuel is supplied to the reactor, and the carbon dioxide in the engine exhaust gas and the incineration ash are reacted for a predetermined time. By making it, it becomes possible to detoxify either or both of lead and hexavalent chromium contained in the incineration ash.

Further, when engine exhaust gas in a stoichiometric state is used, both lead and hexavalent chromium are subjected to aging treatment for 60 minutes or 30 minutes, that is, 350 ° C. to 500 ° C. regardless of the aging treatment time. It has been found that the amount of elution can be suppressed below the soil environmental standard value at an exhaust gas temperature in the range of ° C.
Therefore, engine exhaust gas in a range of 350 ° C. to 490 ° C. from a gas engine operated in a lean burn state or stoichiometric state using hydrocarbons as fuel is supplied to the reactor, and carbon dioxide gas and incineration ash in the engine exhaust gas are supplied. If the reaction is performed for 60 minutes, both lead and hexavalent chromium contained in the incineration ash can be rendered harmless.

[Another embodiment]
(1) The reaction time between carbon dioxide in engine exhaust gas and incineration ash is not limited to 30 minutes or 60 minutes as shown above. For example, incineration ash contains only lead or only hexavalent chromium. In some cases, it can be appropriately set according to the incineration ash to be treated.
(2) Regarding the gas engine, it is not limited to the one used for the power generation at the time of starting up the waste incinerator or the power generation in an emergency, but the gas engine in various commonly used facilities can also be used. .

1 Waste incinerator 2 Reactor 3 Gas engine 4 Gas supply path

Claims (4)

A method of treating incineration ash by treating incineration ash by reacting incineration ash from a waste incinerator with exhaust gas containing carbon dioxide gas in a reactor,
Engine exhaust gas in a range of 340 ° C. to 500 ° C. from a gas engine operated using hydrocarbons as fuel is supplied to the reactor, and carbon dioxide in the engine exhaust gas is reacted with the incineration ash for a predetermined processing time. A method for treating incineration ash that renders lead and hexavalent chromium contained in the incineration ash harmless.   The incineration ash treatment method according to claim 1, wherein the exhaust gas from the gas engine is an engine exhaust gas in a range of 340 ° C to 490 ° C operated in a lean burn state.   The method for treating incinerated ash according to claim 1, wherein the exhaust gas from the gas engine is engine exhaust gas in a range of 350 ° C to 500 ° C operated in a stoichiometric state. An incineration ash treatment facility for carrying out the treatment method according to any one of claims 1 to 3,
Treatment of incineration ash comprising a gas engine operated with hydrocarbons as fuel, and a gas supply path for supplying engine exhaust gas from the gas engine to a reactor into which incineration ash containing lead and hexavalent chromium is introduced Facility.

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