JPH1130410A - Disposing method for waste utilizing waste plastic gasification/ash melting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for effectively utilizing gas, generated through gasification treatment, for incineration disposal of waste to render solid sub stance, discharged through melt treatment, non-noxious by mixing incinerated ash during gasification/melt treatment of waste plastic. SOLUTION: Incinerated ash generated in an incinerator 10 for waste is fed to a waste plastic gasification/ash melting device 24. Waste plastic is partially burnt at a high temperature higher than an ash melt point to effect gasification treatment and decompose dioxin in incinerated ash. Further, melt-treated molten slug is produced in a manner to prevent elusion of heavy metals and reducing atmosphere gas forming fuel is generated. By feeding the reducing atmosphere gas to an incinerator, the generation of an acid component (especially NOx) contained in combustion gas is reduced, and combustion in the incinerator 10 is stabilized and increased in temperature. By reducing an amount of a generating unburnt carbon material (unburnt hydrocarbon), the generation of dioxin is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of gasifying and melting waste plastics separated from plastic waste and general waste, and mixing the waste plastic with incineration ash of general waste and melting the waste plastic. The present invention relates to a method for detoxifying discharged solids and effectively utilizing gas obtained by gasification for incineration of waste such as general waste.

[0002]

2. Description of the Related Art In recent years, the amount of general waste including plastic waste and plastic has been increasing, and the treatment of waste plastic has become one of the problems of the waste disposal problem. On the other hand, waste plastic is a combustible material having a high calorific value and can be efficiently incinerated. Therefore, a technology has been developed in which the separated waste plastic is incinerated to recover waste heat and effectively use the energy. Further, a technique of gasifying the separated waste plastic and using the obtained gasified gas for power generation is being put to practical use.

As a waste gasification and melting furnace, Japanese Patent Application Laid-Open No.
As described in JP-A--60830, a tuyere for blowing an oxygen-containing gas is provided on a side portion of a furnace main body to maintain a molten state such as ash at a lower portion of the furnace main body in a good state, thereby forming a deposition layer. There is known an apparatus which maintains a good flow of gas and maintains a high gas temperature in a free board portion. Japanese Patent Application Laid-Open No. 9-72 discloses a technology for generating electric power using waste heat of waste combustion gas.
As described in JP-A-204, after natural gas is reformed into a hydrogen-rich gas by a fuel reformer, the hydrogen-rich gas is reburned by a combustor, and the resulting gas is generated from waste combustion gas. 2. Description of the Related Art There is known a system in which superheated steam is heated and a steam turbine is driven by the superheated steam to generate power.

[0004]

On the other hand, incinerated ash (bottom ash and fly ash) generated from equipment for incinerating waste such as general refuse contains heavy metals and dioxins. It is necessary to take measures to prevent the elution of heavy metals and to treat incinerated ash containing dioxins. In addition, in high-calorie plastics mixed in incinerators such as general garbage, local high-temperature parts are generated in the incinerator, which may cause damage to the furnace materials. It is effective if you can do it. In addition, in incinerators for general waste, etc., the combustion state is not stable, the temperature inside the furnace may be uneven and the temperature may be lowered, and in this case, one of the causative substances that generate dioxins, such as A large amount of combustible carbon-based substances (unburned hydrocarbons) are emitted to the flue and the like, which promotes the resynthesis of dioxins. Also,
It is also necessary to reduce acidic components such as NOx contained in combustion gas of incinerators such as general waste.

The present invention has been made in view of the above points, and an object of the present invention is to mix incineration ash and the like of general waste with waste plastic when gasifying and melting the separated waste plastic. At the same time as the decomposition of the dioxins contained in the ash, the exhausted solids are melted so that the heavy metals do not elute, and the fuel gas in the reducing atmosphere obtained by gasification is disposed of as general waste. Acidic components (especially NOx) in the combustion gas supplied to the incinerator
At the same time as reducing combustion, stabilize combustion, make the temperature inside the furnace even and raise the temperature, reduce the amount of unburned carbon-based materials generated, and reduce the generation of dioxins. It is to provide a method.

[0006]

In order to achieve the above object, a method for treating waste using gasification and melting of ash of waste plastic according to the present invention is to reduce incineration ash generated from a waste incinerator. Waste plastic gasification with plastic
The waste plastic is supplied to an ash melting device, and the waste plastic is partially burned at a temperature higher than the ash melting point and gasified to generate a reducing atmosphere gas (reducing gas, high-temperature pyrolysis gas), It is characterized in that a dioxin is decomposed and a molten slag that has been subjected to a melting treatment so that heavy metals are not eluted is obtained (see FIGS. 1 and 2).

In the method of the present invention, incineration ash generated from a waste incinerator is supplied to a waste plastic gasification and ash melting device together with waste plastic, and the waste plastic is partially burned at a high temperature above the ash melting point. Gasification treatment to decompose the dioxins in the incineration ash, obtain molten slag that has been melt-processed so that heavy metals do not elute, and generate a reducing atmosphere gas that serves as fuel. Atmosphere gas is supplied to the waste incinerator, and acidic components (particularly, NO
x), stabilize combustion in waste incinerators and increase the temperature, reduce the amount of unburned carbon-based substances (unburned hydrocarbons), and suppress the production of dioxins. It is a feature (see FIG. 1). in this case,
A configuration in which the above-mentioned reducing atmosphere gas is supplied to the combustion section of the above-mentioned waste incinerator without pretreating trace components (HCl, H ₂ S, NH _3, etc.) and dust contained therein. And It is also possible to adopt a configuration in which the reducing atmosphere gas is pretreated to remove trace components and dust, and then supplied to the combustion section of the waste incinerator. It is preferable to treat both bottom ash and fly ash as incineration ash, but it is also possible to treat either bottom ash or fly ash.

In the above-mentioned method of the present invention, it is desirable that the waste plastic gasification and ash melting apparatus is configured to include a swirling flow type spouted bed gasification and ash melting furnace (see FIG. 3). As an example of the swirling type jet bed gasification / ash melting furnace, a horizontal swirling flow gasification / ash melting furnace as shown in FIG. 3 is used. Further, in the method of the present invention, at least any of dust containing sludge and ash components (for example, dust by-produced in the system) is discarded together with incineration ash from a waste incinerator for incinerating general waste and the like. It can be configured to supply to a plastic gasification and ash melting device. In this case, besides incineration ash such as general waste,
For example, construction sludge, water treatment sludge, or the like can be added as an additive and simultaneously melted.

[0009]

Embodiments of the present invention will be described below in detail. FIG. 1 schematically shows an apparatus for implementing a waste treatment method utilizing waste plastic gasification and ash melting according to a first embodiment of the present invention. In this embodiment, a waste plastic gasification and ash melting device is combined with an existing waste incineration power generation facility. As shown in FIG. 1, waste such as general waste is incinerated in an incinerator 10, and combustion gas containing fly ash is introduced into a boiler 12, and the steam generated here is used as a steam turbine 14. Is driven to generate power. 16 is a generator, 1
8 is a condenser. On the other hand, the exhaust gas containing fly ash from the boiler 12 is introduced into the dust collecting device 20, and the exhaust gas from which the fly ash is collected is introduced into the gas treatment device 22 to remove NOx, SOx, etc. Will be released. In addition, as a dust collector 20, a bag filter, an electric dust collector, etc. are mentioned as an example.

The ash (bottom ash) generated from the incinerator 10 and fly ash (fly ash) collected by the dust collecting device 20 are separated into waste plastic gasified and ash together with the separated waste plastic which is the main fuel. The ash is supplied to the melting device 24, where it is partially burned at a high temperature above the ash melting point (for example, about 1300 ° C.) and gasified. At this time, dioxin in the ash is decomposed. As the waste plastic gasification / ash melting device 24, it is desirable to use a device including a swirling flow type spouted bed gasification / ash melting furnace, but the details will be described later. The solid matter discharged from the waste plastic gasification and ash melting device 24 is a molten slag that has been subjected to a melting treatment so that heavy metals are not eluted. Also,
In addition to the above incinerated ash (bottom ash and / or fly ash), waste such as dust and sludge containing ash components may be added to the waste plastic gasification and ash melting device 24. In this case, In addition, these wastes can be simultaneously detoxified by melting. In addition, in addition to incineration ash such as general refuse, for example, construction sludge, water treatment sludge, or the like can be added as an additive. In some cases, the bottom ash is not supplied to the waste plastic gasification / ash melting device 24, but only fly ash is supplied to the waste plastic gasification / ash melting device 24. In this case, a bottom ash supply line connecting the incinerator 10 and the waste plastic gasification and ash melting device 24 is not required.

On the other hand, the gasification gas generated from the waste plastic gasification and ash melting device 24 is free from the pretreatment of trace components (HCl, H ₂ S, NH _3, etc.) and dust contained therein. Is supplied to the combustion section of the incinerator 10. In addition,
It is also possible to adopt a configuration in which the gasified gas is pre-treated to remove trace components and dust, and then supplied to the incinerator 10. This gasification gas is a fuel gas in a reducing atmosphere (mainly composed of CO and H ₂ ), and is produced by the effect of a reducing atmosphere gas, particularly CH ₄ and C ₂ H ₄ contained in the reducing atmosphere gas. The emission of acidic components (particularly, NOx) contained in the combustion gas of the incinerator 10 can be suppressed. In addition, by the effect of mixing the fuel gas, the combustion in the incinerator 10 is stabilized, the temperature in the furnace is made uniform and the temperature is increased, and the amount of unburned carbon-based substances (unburned hydrocarbons) is reduced. Regeneration of dioxins can be suppressed. In some cases, the residual heat from the waste plastic gasification and ash melting device 24 is used to perform district cooling / heating, hot water production, and the like.

Next, an example of the configuration of a waste plastic gasification and ash melting apparatus will be described with reference to FIG.
In a pretreatment step (not shown), the plastic waste or general waste is magnetically separated, then crushed and dried, and then the waste plastic as a raw material is stored in a storage hopper. Precombustor 2
6. On the other hand, incineration ash generated from equipment for incinerating waste such as general waste is also supplied to the pre-combustor 26, and waste plastic and incineration ash are first pre-combusted in the pre-combustor 26. It is also possible to mix waste plastic and incinerated ash with a raw material supply hopper or the like and then supply the mixed waste ash to the precombustor 26.

The pre-combusted waste plastic and incinerated ash are supplied to a partial combustion gasification and ash melting furnace 28 where they are partially burned at a high temperature above the ash melting point (eg, about 1300 ° C.) to gasify. It is processed. The molten slag discharged from the partial combustion gasification / ash melting furnace 28 is cooled by cooling water, pulverized by a slag crusher 30, and discharged as crushed slag. Even when the slag crusher 30 is not provided, the molten slag can be crushed by thermal shock and rapidly discharged as crushed slag by rapidly cooling the molten slag with cooling water. On the other hand, the gasification gas generated in the partial combustion gasification and ash melting furnace 28 is circulated by the heat recovery device 32 by, for example,
After cooling to about 0 ° C., and solid waste such as char is separated and removed by the cyclone 34, the heat recovery device 3
In step 6, the water is cooled to, for example, about 400 ° C. by circulating water. Then, the gasified gas is supplied to a combustion section of an incinerator such as general waste to which the incinerated ash has been supplied. The solid waste such as char separated by the cyclone 34 is circulated to the pre-combustor 26, and is again returned to the partial combustion gasification / ash melting furnace 2.
At 8, it is gasified and melted. The circulating water from which the heat of the gasified gas has been recovered by the heat recovery device 36 is used as low-pressure steam.

FIG. 3 shows a case where the partial combustion gasification / ash melting furnace in the waste plastic gasification / ash melting apparatus is a swirling flow type spouted bed gasification / ash melting furnace.
Here, as an example, a configuration of a horizontal swirling flow gasification and ash melting furnace is illustrated. As shown in FIG. 3, a pre-combustor 40 is provided at an upper portion on the upstream side of a cylindrical furnace body 38 mounted in a lateral direction. A pre-burner 44 is provided for pre-burning the supplied waste plastic and incinerated ash. Combustion air that generates a swirling flow in the furnace is configured to be supplied from a combustion air supply port 46 at an upper portion on the upstream side of the furnace main body 38 in a substantially tangential direction of the furnace cross section. Furnace body 3
A molten slag discharge port 48 is provided in a lower portion on the downstream side of the furnace 8, and a high temperature partial combustion gas (gasified gas) is discharged from a gasified gas outlet 50 downstream of the furnace body 38. 52 is a baffle for damping the molten slag. In FIG. 3, a high-temperature partial combustion gas (gasification gas) is ejected in the lateral direction, but it may be directed upward as in the partial combustion gasification and ash melting furnace 28 shown in FIG. .

In the gasification and melting treatment of waste plastics, a swirling-flow type spouted bed gasification and ash melting furnace is applied to perform partial combustion at a high temperature above the ash melting point (for example, about 1300 ° C.). Thus, a fuel gas having a reducing atmosphere containing CO and H ₂ as main components can be obtained in a short time. In the swirling flow type spouted bed gasification and ash melting furnace, gasification is performed in a high temperature range, so that the generation of tar components and unburned hydrocarbons is small and the gasification rate is increased. Further, since the residence time in the furnace is short, the shape of the furnace becomes compact. Furthermore, gasification treatment of waste plastics including PVC and the like involves generation of chlorine compounds, but in a high temperature range, synthesis of dioxins does not occur, and the ratio of chlorine that is difficult to remove is reduced. In addition, in the swirling flow type spouted bed gasification and ash melting furnace, dioxin in ash such as incinerated ash is decomposed due to high temperature, and solid matter discharged by melting treatment is detoxified slag. Even when waste plastic is melted together with incineration ash, heavy metals do not elute. Furthermore, even if the composition of the waste plastic is non-uniform or non-flammable substances are mixed, it can be separated from the furnace as detoxified molten slag.

Next, another example of the configuration of the waste plastic gasification and ash melting apparatus will be described with reference to FIG. In a pretreatment step (not shown), plastic waste or general waste is magnetically separated, then crushed and dried, and then the waste plastic as a raw material is stored in a storage hopper. Precombustor 2
6. On the other hand, incineration ash generated from a facility for incinerating waste such as general waste is also supplied to the pre-combustor 26, and waste plastic and incineration ash are first pre-combusted in the pre-combustor 26. It is also possible to mix waste plastic and incinerated ash with a raw material supply hopper or the like and then supply the mixed waste ash to the precombustor 26.

The pre-combusted waste plastic and incinerated ash are supplied to a partial combustion gasification and ash melting furnace 28, where they are partially burned at a high temperature above the ash melting point (eg, about 1300 ° C.) to gasify. It is processed. The molten slag discharged from the partial combustion gasification / ash melting furnace 28 is cooled by cooling water, pulverized by a slag crusher 30, and discharged as crushed slag. Further, even when the slag crusher 30 is not provided, the molten slag can be crushed by thermal shock and rapidly discharged as crushed slag by rapidly cooling the molten slag with cooling water. On the other hand, the gasification gas generated in the partial combustion gasification and ash melting furnace 28 is circulated by the heat recovery device 32 by, for example,
After cooling to about 0 ° C., and solid waste such as char is separated and removed by the cyclone 34, the heat recovery device 3
In step 6, the water is cooled to, for example, about 400 ° C. by circulating water. The solid waste such as char separated in the cyclone 34 is circulated to the pre-combustor 26 and is gasified and melted again in the partial combustion gasification and ash melting furnace 28. The circulating water from which the heat of the gasified gas has been recovered by the heat recovery device 36 is used as low-pressure steam.

The gasified gas cooled by the heat recovery device 36 is cooled by the cooling water by the gas cooling device 62 to, for example, 180 g.
℃, then the upstream bag filter 6
After the solid waste such as char is separated and removed in 4, a powder desalinating agent, for example, powdered slaked lime is blown from the desalinating agent supply device 66 and introduced into the downstream bag filter 68. The surface of the bag of the bag filter 68 is coated with a powder desalinating agent (slaked lime) layer, and the corrosive component (HCl) in the introduced exhaust gas reacts with the powdered desalinating agent (slaked lime) to form a corrosive component. Is separated and removed from the gasified gas as CaCl ₂ (solid state). The solid waste such as char separated by the bag filter 64 on the upstream side is circulated to the pre-combustor 26 and gasified and melted again in the partial combustion gasification / ash melting furnace 28. It is also possible to adopt a configuration in which 64 is omitted. Then, the gasification purification gas from which the corrosive component (HCl or the like) has been removed is supplied to an incinerator. Note that 70 is a fan.

[0019]

As described above, the present invention has the following effects. (1) The incineration ash (bottom ash and / or fly ash) generated from the waste incinerator is supplied to the waste plastic gasification and ash melting device together with the waste plastic, and partially burned at a high temperature above the ash melting point. By performing the gasification treatment, dioxin in the ash can be decomposed, and a molten slag that has been subjected to a melting treatment so that heavy metals do not elute can be obtained. (2) The incineration ash (bottom ash and / or fly ash) generated from the waste incinerator is supplied to the waste plastic gasification and ash melting device together with the waste plastic, and partially burned at a high temperature above the ash melting point. By performing the gasification process, a fuel gas in a reducing atmosphere is generated.
This reducing atmosphere gas is supplied to the waste incinerator,
The effect of the reducing atmosphere gas can reduce acidic components (especially NOx) contained in the combustion gas of the waste incinerator, and the effect of mixing the fuel gas can reduce the combustion in the waste incinerator. Stabilization and high temperature can be achieved, and the generation of unburned carbon-based substances (unburned hydrocarbons) can be reduced to suppress the generation of dioxins. (3) When the gasification and ash melting device for waste plastics is configured to include a swirling flow type spouted bed gasification and ash melting furnace, the generation of tar and unburned hydrocarbons is small and the gasification rate is high. Become. Further, the shape of the furnace can be made compact. In addition, dioxins are not generated, and the ratio of chlorine that is difficult to remove is reduced. Furthermore, even if the composition of the waste plastic is non-uniform or non-flammable substances are mixed, it can be separated from the furnace as detoxified molten slag. (4) At least one of dust and sludge (construction sludge, water treatment sludge, etc.) containing ash components is supplied to waste plastic gasification and ash melting equipment together with incineration ash from a waste incinerator that incinerates general waste. In the case of a configuration in which these are performed, these can be simultaneously melt-processed. (5) If waste plastics are separated from general waste and gasified with a gasification and ash melting device, and the waste excluding waste plastics is incinerated in an incinerator, Can be suppressed from occurring, and damage to the furnace material can be prevented.

[Brief description of the drawings]

FIG. 1 is a systematic schematic configuration diagram showing an apparatus for implementing a waste treatment method using waste plastic gasification and ash melting according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an example of a waste plastic gasification and ash melting apparatus according to the present invention.

FIG. 3 is a schematic configuration diagram showing an example of a swirling type jet bed gasification and ash melting furnace of the present invention.

FIG. 4 is a schematic configuration diagram showing another example of a waste plastic gasification and ash melting apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Incinerator 12 Boiler 14 Steam turbine 16 Generator 18 Condenser 20 Dust collection device 22 Gas treatment device 24 Waste plastic gasification and ash melting device 26, 40 Precombustor 28 Partial combustion gasification and ash melting furnace 30 Slag crushing Machine 32, 36 Heat recovery device 34 Cyclone 38 Furnace main body 42 Input port for waste plastic etc. 44 Pre-burning burner 46 Air supply port for combustion 48 Melt slag discharge port 50 Gasification gas outlet 52 Baffle 62 Gas cooling device 64, 68 Bag filter 66 Desalting agent supply device 70 fan

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C08J 11/12 ZAB F23G 5/14 ZABF C10J 3/00 ZAB 7/00 ZAB C10L 3/00 ZAB 102B F23G 5/00 115 7 / 12 ZABZ 5/14 ZAB F23J 1/00 B 7/00 ZAB C10G 1/10 102 B01D 53/34 129B 7/12 ZAB 134E F23J 1/00 B09B 3/00 302A // C10G 1/10 303L C10L 3/00 ZABZ (72) Inventor Kenjiro Shindo 1-1, Kawasaki-cho, Akashi-shi, Hyogo Prefecture, inside the Akashi Plant of Kawasaki Heavy Industries, Ltd. (72) Inventor Yasutoshi Shoji 2-4-1 Hamamatsucho, Minato-ku, Tokyo Kawasaki Heavy Industries, Ltd. East Kobe Head Office (72) Inventor Shuichi Morioka 1-3-1 Higashi Kawasaki-cho, Chuo-ku, Kobe Kawasaki Heavy Industries, Ltd.Kobe Head Office (72) Inventor Jun Sodeyama 1780 Kamikono, Yachiyo-shi, Chiba Kawasaki Heavy Industries Ltd. Yachiyo factory

Claims (4)

[Claims] 1. An incineration ash generated from a waste incinerator is supplied to a waste plastic gasification and ash melting device together with waste plastic, and the waste plastic is partially burned at a temperature higher than the ash melting point to be gasified. And gasification and ash melting of waste plastics, characterized by generating reducing atmosphere gas, decomposing dioxins in incinerated ash, and obtaining molten slag that has been melt-processed so that heavy metals do not elute. Waste treatment method used. 2. The incineration ash generated from the waste incinerator is supplied to a waste plastic gasification and ash melting device together with the waste plastic, and the waste plastic is partially burned at a temperature higher than the ash melting point to be gasified. Decomposing the dioxins in the incineration ash, and obtaining a molten slag that has been melt-processed so that heavy metals are not eluted, and generating a reducing atmosphere gas serving as a fuel; Supply to the incinerator to reduce the acidic components contained in the combustion gas of the waste incinerator, stabilize the combustion in the waste incinerator and increase the temperature, and reduce the amount of unburned carbon-based materials generated. A waste treatment method utilizing waste plastic gasification and ash melting, characterized in that the generation of dioxins is suppressed by reducing the amount. 3. A waste plastic gasification and ash melting device,
3. The method for treating waste using waste plastic gasification and ash melting according to claim 1 or 2, further comprising a swirling flow type spouted bed gasification and ash melting furnace. 4. A waste plastic gasification and ash melting device together with incineration ash from a waste incinerator, wherein at least one of sludge and dust containing ash components is supplied.
Or a waste disposal method utilizing waste plastic gasification and ash melting according to 3.