JP4662338B2 - Waste combined gasification processing system and method - Google Patents

Description

The present invention, flow and gas treatment system having a Doso gasification furnace, wet waste and comprising a methane fermentation processing system having a methane fermentation tank for methane fermentation treatment of waste composite gas processing system and method About.

Conventionally, in order to recover energy from organic solid waste such as municipal waste, sewage sludge, biomass, and industrial waste, the waste is heated and pyrolyzed and reformed, and flammable gas (gasification gas) Gas conversion technology that collects lime is attracting attention from the viewpoints of environmental conservation and resource saving.
In this gasification treatment, a gasification agent such as water vapor, oxygen, air or the like is introduced into a gasification furnace to which waste is supplied, and a gasification reaction is performed to generate a gasification gas. The gasification gas is reformed into a reforming gas rich in CO and H _{2 in} a reforming furnace such as a cracking apparatus after the gasification furnace. The reformed gas thus obtained is introduced into a boiler that sends steam to a steam turbine that drives a generator, and then impurities in the gas are removed by a bag filter, a gas purification device, etc., and used as a fuel gas. It is sent to power generators. That is, the gasified gas is used in an internal combustion engine such as a gas engine or a gas turbine, a heat cycle engine, or a heat source device, and the heat energy of the gasified gas is converted into a heat medium such as steam or an energy form such as electric power and is effective. Used.

Various types of gasification treatment have been proposed and put into practical use, and one of them is a fluidized bed gasification furnace that heats and gasifies directly by partial combustion while flowing waste (patent) Reference 1).
This is a device that introduces a gasifying agent, which is a mixed gas of oxygen and water vapor, from the bottom of the furnace and heats it while flowing the waste to gasify it. it can. At this time, the waste is thermally decomposed to become a gaseous substance while being heated to about 400 to 800 ° C., for example, and comes into contact with oxygen and water vapor of the gasifying agent, and a part thereof is combusted in the furnace. In the reforming furnace, a combustion reaction and a water gasification reaction (reforming reaction) are performed, and a gasification gas containing carbon monoxide, hydrogen, methane, ethane, carbon dioxide, etc., and unburned tar, soot, etc. This produces solids, fly ash, and incombustibles.

The incombustible material is discharged out of the system from the lower part of the gasifier. On the other hand, the gasified gas, unburned solids, and fly ash are fed from the upper part of the gasification furnace to the reforming furnace at the subsequent stage. In the reforming furnace, a gasifying agent which is a mixed gas of oxygen (or air) and water vapor is supplied into the furnace, and the gasification gas undergoes a water gasification reaction by the gasifying agent. That is, unburned solids such as methane, ethane, tar, and soot in the gasification gas are reduced in molecular weight, and a reformed gas containing clean CO and H ₂ rich gas is generated.
In an apparatus using such a fluidized bed gasification furnace, a gasifying agent is supplied to the fluidized bed gasification furnace, but the gasifying agent not only gasifies the waste but also flows the waste in the furnace. In order to maintain the fluidity, an amount more than the amount necessary for gasification was introduced. As a result, there is a problem that the partial combustion rate of the waste is increased and the calorie of the gasification gas is reduced.

On the other hand, wet waste with a high moisture content among organic wastes requires a large amount of heat energy for drying when used for gasification, so methane fermentation is suitable for recovering energy from waste. ing. In methane fermentation treatment, organic matter in waste is decomposed by the action of microorganisms under anaerobic conditions, and methane gas is recovered as fuel gas.
Therefore, when various wastes are treated comprehensively, it is preferable to use a method in which gasification treatment and methane fermentation treatment are combined, as described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2001-276772). In Patent Document 2, methane gas is recovered by methane fermentation of wet organic waste in a methane fermentation tank, gasification gas is recovered by gasifying solid organic waste in a gasification furnace, and these fuel gases are gasified. Electric power is generated by a generator that is introduced into the turbine and connected to the gas turbine. Patent Document 2 also proposes a configuration in which the methane fermentation residue is dried using the heat of the gas turbine exhaust gas, the generated power is used in the system, and the fermenter is heated by exhaust heat from the generator. is doing.

Japanese Patent No. 3079051 JP 2001-276772 A

As described above, when using a fluidized bed gasification furnace in gasification treatment, if the gasifying agent is used as the fluidizing gas, the supply amount of the gasifying agent becomes excessive, the fuel gas becomes low in calories, and effective. There is a problem that the recovery of the fuel gas is reduced. Therefore, it is also conceivable to use exhaust gas as a fluidizing gas, the flue gas often impurities, decrease the recovery rate of the fuel gas, Ru惧Regaa deteriorating the quality degradation and the subsequent device.

An object of the present invention is generated in these processing systems when a composite gasification processing system including a gasification processing system including the fluidized bed gasification furnace and a methane fermentation processing system including a methane fermentation tank is constructed. It is an object of the present invention to provide a composite waste gasification processing system and method capable of effectively using products and effectively using resources and reducing emissions from the viewpoint of environmental conservation.

Therefore, in order to solve this problem, the present invention provides:
A gas equipped with a fluidized bed gasification furnace that introduces a fluidizing gas from a fluidizing gas inlet at the bottom of the furnace and heats the organic solid waste while flowing it, and gasifies the waste by introducing a gasifying agent. Methane gas from fermentation gas generated in the methane fermentation tank in a combined waste gasification processing system comprising a methane fermentation treatment system comprising a methane fermentation treatment system and a methane fermentation treatment system comprising a methane fermentation tank for treating methane fermentation of wet waste A gas separation device that separates carbon dioxide from carbon dioxide, and a carbon dioxide feed line that feeds the separated carbon dioxide to the fluidizing gas inlet, from a gasification processing system including the fluidized bed gasification furnace An ash cleaning means for wet-cleaning the generated ash is provided, and the ash cleaning means is configured so that carbon dioxide separated and recovered by the gas separator is introduced and the ash is wet-cleaned in the presence of carbon dioxide. And, further, methane was separated and recovered by the gas separation apparatus, and supplying the methane gas is supplied as a combustion improver for reforming furnace constituting the gasification process system to a gas engine with a fuel gas.

Et al is provided with the gas separation apparatus, a treatment tank for circulating the fermentation gas, a vacuum exhaust means for evacuating said processing vessel, and carbon dioxide adsorbent provided inside the processing tank, and Preferably, carbon dioxide contained in the fermentation gas is selectively adsorbed and separated by the carbon dioxide adsorbent by a vacuum pressure swing adsorption method.

According to the present invention, carbon dioxide is separated and recovered from the fermentation gas generated in the methane fermentation treatment system, and is used as a fluidizing gas in the gasification treatment system, so that carbon dioxide is not supplied from the outside. The carbon dioxide generated in can be used effectively. Thus, according to the present invention, by effectively combining the gasification treatment system and the methane fermentation treatment system to effectively use the product, a resource circulation cycle is formed, and the resource is effectively used and discharged. A reduction in weight can be achieved.
Also, carbon dioxide contained in the fermentation gas can be selectively separated and recovered by a vacuum pressure swing adsorption method, whereby carbon dioxide having a high concentration can be recovered. Of course, methane gas can also be recovered as the fuel gas, and it is possible to always obtain high purity fuel gas.

Furthermore, the gasifying agent introduced into the fluidized bed gasifier is oxygen and water vapor,
The fluidized bed gasification furnace includes CO ₂ introduction amount control means for controlling the introduction amount of carbon dioxide into the furnace, O ₂ introduction amount control means for controlling the oxygen introduction amount into the furnace, and water vapor into the furnace. H ₂ O introduction amount control means for controlling the introduction amount, and each introduction amount control means is independently controlled.
As described above, by independently controlling the amount of carbon dioxide introduced, the amount of oxygen introduced, and the amount of steam introduced into the fluidized bed gasifier, the amount of water vapor and the amount of oxygen can be optimized and fluidized optimally. Thus, highly efficient gasification can be achieved.
The carbon dioxide introduction amount is controlled based on the waste input amount and the fluid medium amount into the fluidized bed, the oxygen introduction amount is controlled based on the waste input amount, and the water vapor introduction amount is It is preferably controlled based on the total carbon content.

Also, pre-Sharing, ABS cleaning means, the introduced carbon dioxide was separated and recovered by a gas separation apparatus, characterized in that the ash is configured to wet cleaning in the presence of carbon dioxide.
Conventionally, ash discharged from such waste heat treatment equipment contains heavy metals and chlorine that have a negative effect on quality when reused in cement raw materials, fine aggregates, etc. It was washed away by washing with water. However, with regard to chlorine in the ash, a hardly soluble Friedel's salt is formed at the time of water washing, and it may remain in the ash without being eluted only by water washing.

According to the present invention, as described above, when ash is suspended and washed with a washing solution such as water, by supplying carbon dioxide and washing in the presence of carbon dioxide, Friedel's salt in the ash is obtained. Carbonates and promotes elution of chlorine. In addition, heavy metals that cannot be washed away with the washing solution can be carbonated by introduction of carbon dioxide and can be prevented from elution, so that they can be fixed in ash and rendered harmless.
In this way, by washing in the presence of carbon dioxide when washing the ash with the washing solution, it is possible to reliably suppress elution of heavy metals and remove chlorine, and to make the ash suitable for reuse. can do.

Further, the ash cleaning means is provided in a plurality of stages in series, the ash cleaning means on the front stage side initially removes heavy metals and chlorine by washing the ash with a cleaning solution, and the carbon dioxide in the ash cleaning means on the rear stage side. It is preferable to carry out carbonation of heavy metals and further removal of chlorine by wet cleaning in the presence.
According to the present invention, most heavy metals are eluted and removed by wet cleaning without introducing carbon dioxide in the ash cleaning means on the front stage side, and wet in the presence of carbon dioxide in the ash cleaning means on the rear stage side. Washing stabilizes heavy metals remaining in the ash by carbonation and elutes insoluble chlorine such as Friedel's salt.
This is because heavy metals contained in the ash may be fixed and remain in the ash at a high concentration when the carbonation step is first performed in the ash cleaning. By carrying out the carbonation step after eluting most of the metals in the heavy metal initial removal step, it is possible to reduce the heavy metal content in the ash and the chlorine content.

Moreover, it is invention of a method, Comprising: The organic waste which heats while flowing an organic solid waste with the fluidization gas introduce | transduced in the fluidized-bed gasification furnace, and gasifies this waste by introduction | transduction of a gasifying agent In a composite waste gasification method comprising: a gasification treatment step of methane fermentation of a wet waste, and an ash washing step for washing ash generated in the gasification treatment step In the methane fermentation treatment step, after separating methane gas and carbon dioxide from the fermentation gas generated by the methane fermentation by a vacuum pressure swing adsorption method, the separated carbon dioxide is introduced into the fluidized bed gasification furnace And the ash cleaning step, the ash cleaning step wet-cleans the ash in the presence of the introduced carbon dioxide, and the separated methane gas is the gasification The methane gas is supplied as a combustion improver for reforming furnace constituting the management system and supplying to the gas engine as fuel gas.

Also, in the gas treatment step, introducing oxygen and steam into the fluidized bed gasification furnace as a gasifying agent, and the introduction amount of the oxygen, and the introduction amount of the steam, dioxide as the fluidizing gas It is characterized in that the amount of carbon introduced is independently controlled.

In addition, the pre-Sharing, ABS cleaning process, the methane fermentation step dioxide separated from the fermentation gas is introduced at, the ash, characterized in that wet cleaning in the presence of carbon dioxide.
Furthermore, in the ash cleaning step, ash cleaning is performed in stages, heavy metals and chlorine are initially removed by ash cleaning with a cleaning solution on the front side, and in the presence of carbon dioxide on the rear side. The carbonation and chlorine removal of heavy metals is performed by washing of the metal.

According to the present invention as described above, by effectively utilizing the product was organically combining a gas treatment system and methane fermentation treatment system is circulated cycles resources formation, effective utilization and resources Reduction of emissions can be achieved.
Furthermore, carbon dioxide contained in the fermentation gas generated in the methane fermentation treatment system can be selectively separated and purified by a vacuum pressure swing adsorption method, so that carbon dioxide having a high concentration can be recovered.

Furthermore, by independently controlling the amount of carbon dioxide introduced, the amount of oxygen introduced, and the amount of steam introduced into the fluidized bed gasifier, the amount of water vapor and the amount of oxygen can be optimized and fluidized. Efficient gasification can be achieved.
Moreover, when washing | cleaning ash with a washing | cleaning solution, a heavy metal and chlorine can be removed reliably by wash | cleaning in the presence of a carbon dioxide in a front | former stage and a back | latter stage, and an ash can be detoxified.

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.
The organic waste to be treated in the present invention is a solid waste treated in a gasification treatment system, for example, municipal waste, sewage sludge, solid fuel, biomass, etc., and a wet system treated in a methane fermentation treatment system. Examples of the waste include septic tank sludge, human waste, livestock manure, and garbage.
FIG. 1 is an overall configuration diagram of a composite waste gasification processing system according to an embodiment of the present invention, FIG. 2 is a diagram showing a schematic configuration of a fluidized bed gasification furnace shown in FIG. 1, and FIG. 3 is shown in FIG. It is a figure which shows schematic structure of a VPSA apparatus.

As shown in FIG. 1, the composite waste gasification processing system according to the present embodiment processes a gasification processing system including a fluidized bed gasification furnace 10 for processing solid waste, and wet waste. Therefore, the methane fermentation treatment system including the methane fermentation tank 30 is combined.
The gasification processing system includes a fluidized bed gasification furnace 10 for heating and gasifying solid waste, a PSA (pressure swing adsorption method) apparatus 11 for supplying oxygen to the fluidized bed gasification furnace 10, and the fluidization. A reforming furnace 12 connected to the gas outlet of the bed gasification furnace 10 via a flow path, a boiler 13 connected to the gas outlet of the reforming furnace 12 via a flow path, and a steam feed of the boiler 13 A steam turbine 14 connected to the outlet via a flow path, a generator 15 connected to a drive shaft of the steam turbine 14, and a temperature reducing tower 16 connected to the gas outlet of the boiler 13 via a flow path The bag filter 17 and the gas purification device 18 provided in the subsequent stage of the temperature reducing tower 16 in sequence, the gas engine 19 connected to the gas delivery port of the gas purification device 18 through the flow path, and the gas engine 19 are connected. And the generated generator 20.

Further, the gasification processing system includes a first water wash that removes heavy metals in the ash by wet-cleaning the ash generated and recovered in the reforming furnace 12, the boiler 13, the temperature reducing tower 16, and the bag filter 17. A device 21; a second water-washing device 22 that introduces carbon dioxide into the washed ash to remove and detoxify chlorine and heavy metals in the ash; a dehydrator 23 that dehydrates the washed ash; and a dehydrated ash An ash treatment system comprising a drying device 25 for drying and a wastewater treatment facility 24 for treating water generated by dehydration is provided.
On the other hand, the methane fermentation treatment system separates the carbon dioxide 33 from the methane fermentation tank 30 for methane fermentation of the wet waste, and the fermentation gas generated in the methane fermentation tank 30, and clean methane gas 34 and carbon dioxide 33 VPSA (vacuum pressure swing adsorption method) device 31 and gas engine 32 that generates electricity using methane gas as fuel gas.

  FIG. 2 shows a schematic configuration of the fluidized bed gasification furnace 10 and the reforming furnace 12 in the gasification processing system. The solid waste is stored in the storage hopper 101 and quantitatively supplied to the fluidized bed gasification furnace 10 through the screw feeder 102. In the fluidized bed gasification furnace 10, a solid waste supply port 103 is provided in the wall portion of the furnace body 104, and a fluidized bed 105 in which a fluid medium such as sand is stored is formed below. A fluidizing gas is introduced from a fluidizing gas inlet provided below the furnace, and the fluidized bed 105 is fluidized. As the fluidizing gas, carbon dioxide recovered by the VPSA device 31 is used. Further, in addition to the fluidizing gas, oxygen and water vapor are mixed as a gasifying agent by a mixing valve 107 and introduced as a mixed gas from the furnace bottom. The solid waste supplied into the fluidized bed is thermally decomposed into a gaseous substance in the fluidized bed that floats and flows, and comes into contact with the gasifying agent oxygen and water vapor, and part of it is fluidized bed gasified. Partial combustion occurs in the furnace, and the temperature reaches 400 to 650 ° C. At this time, the inside of the furnace may be heated by the auxiliary burner 106 as necessary.

In this combustion, the fluidized gasification furnace 10 mainly causes a combustion reaction represented by the following formula (1) and a water gasification reaction (reforming reaction) represented by the following formula (2), and carbon monoxide, hydrogen, methane, This produces gasified gas containing ethane, carbon dioxide and the like, unburned solids such as tar and soot, fly ash, and incombustibles. In addition, hydrocarbons such as methane, ethane, and tar and unburned solids such as soot cause a reforming reaction represented by the following formula (3) to generate carbon monoxide and hydrogen.
C + O ₂ → CO ₂ + heat (1)
C + H ₂ O → CO + H ₂ (2)
_{C m H m + mH 2 O} → mCO + (m + n / 2) H 2 ... (3)
Incombustibles are discharged from the lower part of the fluidized bed gasification furnace 10, and the fluid containing the gasification gas, unburned solids and fly ash is sent from the upper part to the reforming furnace 12 through the flow path. It is done.

Further, in this embodiment, carbon dioxide is introduced as a fluidizing gas, and since carbon dioxide is an inert gas, most of it is unreacted and used only for fluidization. When reaction heat is supplied in the reforming furnace 12 at the subsequent stage, a part of carbon dioxide generates carbon monoxide by the reaction of the following formula (4).
C + CO ₂ → 2CO (4)
In this way, by introducing carbon dioxide as a fluidizing gas, it is possible to optimize the amount of gasifying agent used without excessively using a gasifying agent such as water vapor or oxygen, and fuel gas can be extracted from carbon dioxide. It can also be generated.

Further, these introduced gases are controlled as follows.
That is, the amount of carbon dioxide introduced to be used as the fluidizing gas is controlled based on the amount of fluidized medium in the fluidized bed and the amount of waste introduced into the furnace. Further, the amount of water vapor introduced is controlled based on the total amount of carbon in the waste because the carbon content in the waste is converted to carbon monoxide by a water gasification reaction. Furthermore, since the amount of oxygen introduced is required for partial combustion of waste, it is controlled based on the amount of waste input. Therefore, it is preferable to provide control means (not shown) for controlling them independently and to control these control means independently.

The gas outlet at the upper part of the fluidized bed gasification furnace 10 is connected to the lower inlet of the reforming furnace 12 through a flow path. In the reforming furnace 12, the gasification gas undergoes a water gasification reaction similar to the equation (2) with water vapor contained in the fluid fed from the fluidized bed gasification furnace 10 at a temperature of about 1000 ° C. That is, methane in the gasification gas, ethane, optionally non燃固form of stray to entrained tars and soot clean contains no soot is low molecular weight CO, rich reformed gas H ₂ Is generated. In addition, when the amount of steam and oxygen is insufficient in the reforming reaction in the reforming furnace, steam and oxygen may be separately supplied.

The PSA apparatus 11 for supplying oxygen to the fluidized bed gasification furnace 10 is a well-known apparatus for separating oxygen gas from a source gas containing oxygen by PSA (pressure swing adsorption method) using an adsorbent. Air is preferably used as the source gas.
The methane fermentation tank 30 is supplied with wet waste and decomposes organic matter contained in the waste by methane bacteria under anaerobic conditions, and fermented with fermentation residue, methane and carbon dioxide as main components. Generate gas.

  As the VPSA device 31, for example, one having the configuration shown in FIG. 3 is used. The fermentation gas generated in the methane fermenter contains sulfur impurities such as hydrogen sulfide, organosilicon impurities such as siloxane, water, and the like in addition to methane gas and carbon dioxide as main components. Therefore, in this embodiment, in addition to separating methane gas and carbon dioxide, these impurities are also removed and the gas is purified.

Specifically, the VPSA device 31 includes a plurality of adsorption towers 301 that are connected in parallel, a blower 303 that circulates fermentation gas from the lower side to the upper side of the adsorption tower 301, and the inside of these adsorptions and the like. An adsorbent that adsorbs target impurities such as siloxane, H ₂ S, H ₂ O, and the like, is arranged in the tower so as to partition the lower side and the upper side of the adsorption tower 301 with a vacuum pump 304 that performs vacuum exhaust. 302, a plurality of adsorption towers 305 that are connected in parallel, and a blower 307 that circulates the fermentation gas circulated from the lower side to the upper side of the adsorption tower 305 from the lower side to the upper side of the adsorption tower 305, A vacuum pump 308 for evacuating the adsorption tower 305, a carbon dioxide adsorbent 306 disposed in the tower so as to partition the lower side and the upper side of the adsorption tower 305, and adsorbing carbon dioxide A surge tank which is an exhaust gas re-feeding means for causing the exhausted gas in the adsorption tower 305 to flow again from one side of the adsorption tower 301 to the other side and to flow again from the other side of the adsorption tower 301 to the one side. 309.

In the treatment of the fermentation gas, first, the fermentation gas is introduced into the adsorption tower 301 by operating the valve and the blower 303, and the adsorbent 302 is passed through the adsorption tower 301 (at a pressure of about 1 ata) so that siloxane, H ₂ S, The target impurities such as H ₂ O are separated and removed. When the adsorption capacity of the adsorbent 302 approaches a saturated state, the inside of the adsorption tower 301 is evacuated by the vacuum pump 304 (about 0.1 ata), and the impurities adsorbed and removed by the adsorbent 302 are removed to adsorb the adsorption tower 301. Then, the adsorbent 302 is regenerated.
Next, the gas sent out from the adsorption tower 301 is introduced into the adsorption tower 305, and the adsorbent 306 is passed through the adsorption tower 305 (at a pressure of about 1 ata) to separate CO _2. Collect in the tank 309. Similarly to the above, when the adsorption capacity of the adsorbent 306 approaches a saturated state, the inside of the adsorption tower 305 is evacuated by the vacuum pump 308 (about 0.1 ata), and the CO ₂ adsorbed and removed by the adsorbent 306 is desorbed. Then, the adsorbent 306 is regenerated from the adsorption tower 305 in a surge tank. The purified gas sent from the upper part of the adsorption tower 305 is recovered as methane gas with high purity.

The operation of this embodiment will be described. First, solid waste is dried to a predetermined moisture content by a dryer or the like and then charged into the fluidized bed gasification furnace 10. In the fluidized bed gasification furnace 10, carbonization as a fluidization gas and water vapor and oxygen as gasification agents are introduced, and gasification mainly composed of carbon monoxide and hydrogen is performed by the above-described gasification reaction, combustion reaction, and the like. Gas is generated. This gasification gas is supplied to the reforming furnace 12 at the subsequent stage, and is reformed by the reforming furnace 12 into a clean carbon monoxide and hydrogen-rich reformed gas that does not contain soot and the like.
The reformed gas is fed from the reforming furnace 12 to the boiler 13 where it is heat recovered. The boiler 13 generates steam by heating water with the heat recovered from the reformed gas. The steam is supplied to the steam turbine 14, and the power is generated by rotating the turbine and driving the generator 15. The steam discharged from the steam turbine 14 is fed to a condenser, where it is returned to water and supplied again to the boiler.

  The reformed gas that has passed through the boiler 13 is fed to the temperature-decreasing tower 16, and the temperature is lowered by water spray or the like to a temperature at which it can be fed to the bag filter 17 at the subsequent stage. The temperature-reduced reformed gas is sent to the bag filter 17, where dust and hydrochloric acid are removed, and then impurities are removed by contact with the catalyst in the gas purifier 18 and sent to the gas engine 19. The generator 20 is driven. In addition to the gas engine described above, the generator includes a gas turbine power generator, a fuel cell power generator, a gas engine-steam turbine power generator, a gas turbine-steam turbine power generator, and a fuel cell-steam turbine power generator. It is also possible to use a fuel cell-gas engine-steam turbine power generator or the like.

In this embodiment, a steam supply line for introducing a part of the steam discharged from the steam turbine 14 into the fluidized bed gasification furnace 10 is provided. The supplied water vapor is used as a gasifying agent for the fluidized bed gasification furnace 10.
Further, a power transmission line for transmitting the power generated by the generator 15 (or the generator 20) to the VPSA device 31 is provided. The transmitted power is used in the VPSA device 31. In addition, a power transmission line for transmitting the power generated by the generator 20 (or the generator 15) to the PSA device 11 is provided. The transmitted power is used in the PSA device 11.

The ash collected by the reforming furnace 12, boiler 13, temperature reducing tower 16, and bag filter 17 is washed with the first water washing device 21, and most of heavy metals are washed away, and then with the second water washing device 22. Washed with water in the presence of carbon dioxide, eluting chlorine in ash and immobilizing heavy metals.
In the second water washing device 22, the ash is carbonated by washing the ash in the presence of carbon dioxide, and the carbonate contains the heavy metals contained by the formation of the carbonate, and the hardly soluble Friedel salt. Elute. (See formula (5) below))
3CaO · Al ₂ O ₃ · CaCl ₂ · 10H ₂ O + CO ₂ (g) + H ₂ O (l)
→ CaCO3 + 2HCl (5)
Thus, by wet-cleaning ash in the presence of carbon dioxide, heavy metals and chlorine can be easily and effectively rendered harmless, and ash can be used as a raw material suitable for reuse.

In this way, the heavy metals and ash in the ash that have been eluted, fixed and rendered harmless, the ash dehydrated by the dehydrator 23 and then dried by the drying device 25 using methane gas as fuel, Reused as fine aggregate.
The dewatered waste water is discharged after various harmful components are removed by the waste water treatment device 24 and purified to the discharge standard.

Meanwhile, the wet waste is methane-fermented in the methane fermentation tank 30 and decomposed into fermentation gas and fermentation residue mainly composed of methane gas and carbon dioxide, and the fermentation residue is fluidized bed gas together with the solid waste. Processed in the furnace 10. The fermentation gas is supplied to the VPSA device 31 where sulfur impurities, organosilicon impurities and the like are separated and removed, and separated and purified into high-purity methane gas and carbon dioxide.
The methane gas is used as a combustion aid for the reforming furnace 12, a fuel gas for the gas engine 32, or a fuel gas for the drying device 24.
The carbon dioxide is supplied to the fluidized bed gasification furnace 10 and used as a fluidizing gas. Further, the carbon dioxide is supplied to the second water washing device 22 to be used for detoxifying ash such as chlorine removal from ash and carbonation of heavy metals.
According to the present embodiment, by effectively combining the gasification processing system and the methane fermentation processing system to effectively use the product, a resource circulation cycle is formed, and the resource is effectively used and the emission is reduced. Can be achieved.

1 is an overall configuration diagram of a composite waste gasification processing system according to an embodiment of the present invention. It is a figure which shows schematic structure of the fluidized bed gasification furnace shown in FIG. It is a figure which shows schematic structure of VPSA shown in FIG.

DESCRIPTION OF SYMBOLS 10 Fluidized bed gasification furnace 11 PSA apparatus 12 Reforming furnace 13 Boiler 14 Steam turbine 16 Temperature reduction tower 17 Bag filter 18 Gas purification apparatus 19 Gas engine 21 1st water washing apparatus 22 2nd water washing apparatus 30 Methane fermentation tank 31 VPSA apparatus 32 Gas engine 33 Carbon dioxide 34 Methane gas

Claims (7)

A gas equipped with a fluidized bed gasification furnace that introduces a fluidizing gas from a fluidizing gas inlet at the bottom of the furnace and heats the organic solid waste while flowing it, and gasifies the waste by introducing a gasifying agent. In a combined waste gasification processing system comprising a methane treatment system and a methane fermentation treatment system comprising a methane fermentation tank for methane fermentation of wet waste,
  A gas separation device for separating methane gas and carbon dioxide from fermentation gas generated in the methane fermentation tank, and a carbon dioxide feed line for feeding the separated carbon dioxide to the fluidizing gas inlet,
Ash cleaning means for wet-cleaning ash generated from a gasification processing system including the fluidized bed gasification furnace is provided, and the ash cleaning means is introduced with carbon dioxide separated and recovered by the gas separation device, Configured to wet-clean in the presence of carbon,
Further, the methane gas separated and recovered by the gas separation device is supplied as a combustion aid for a reforming furnace constituting the gasification processing system and is supplied to a gas engine using methane gas as a fuel gas. Gasification processing system. The gas separation device comprises a processing tank for circulating the fermentation gas, a vacuum exhaust means for exhausting the inside of the processing tank under reduced pressure, and a carbon dioxide adsorbent provided inside the processing tank, and a vacuum pressure swing adsorption The composite waste gasification system according to claim 1, wherein carbon dioxide contained in the fermentation gas is selectively adsorbed and separated by the carbon dioxide adsorbent by a method. The gasifying agent introduced into the fluidized bed gasifier is oxygen and water vapor,
The fluidized bed gasification furnace includes CO ₂ introduction amount control means for controlling the introduction amount of carbon dioxide into the furnace, O ₂ introduction amount control means for controlling the oxygen introduction amount into the furnace, and water vapor into the furnace. The composite waste gasification system according to claim 1, further comprising an H ₂ O introduction amount control means for controlling the introduction amount, wherein each introduction amount control means is independently controlled . The ash cleaning means is provided in a plurality of stages in series, the ash cleaning means on the front stage side initially removes heavy metals and chlorine by cleaning the ash with a cleaning solution, and the ash cleaning means on the rear stage side is in the presence of the carbon dioxide. 2. The composite waste gasification system according to claim 1, wherein carbonation and chlorine removal of heavy metals are carried out by washing . Gasification treatment step of organic waste, in which organic solid waste is heated while fluidizing with fluidized gas introduced into a fluidized bed gasification furnace, and the waste is gasified by introducing a gasifying agent, and wet In a combined waste gasification method comprising: a methane fermentation treatment step for methane fermentation of a system waste,
Including an ash cleaning step for cleaning the ash generated in the gasification step,
In the methane fermentation treatment step, after separating methane gas and carbon dioxide from the fermentation gas generated by the methane fermentation by a vacuum pressure swing adsorption method,
The separated carbon dioxide is introduced into the fluidized bed gasification furnace and introduced into the ash washing step, and the ash washing step performs wet washing in the presence of the introduced carbon dioxide in the ash washing step,
Further, the separated methane gas is supplied as a combustor for a reforming furnace constituting the gasification processing system and is supplied to a gas engine using methane gas as a fuel gas. . In the gasification treatment step, oxygen and water vapor are introduced into the fluidized bed gasification furnace as a gasifying agent, the amount of oxygen introduced, the amount of water vapor introduced, and the introduction of carbon dioxide as the fluidizing gas. 6. The composite waste gasification method according to claim 5, wherein the amount is independently controlled . In the ash washing step, ash washing is performed in stages, heavy metals and chlorine are initially removed by washing the ash with a washing solution on the front side, and washing in the presence of carbon dioxide on the back side. 6. The combined waste gasification method according to claim 5, wherein carbonation and chlorine removal of heavy metals are performed .

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