WO2001083126A1

WO2001083126A1 - Fly ash treating method and device

Info

Publication number: WO2001083126A1
Application number: PCT/JP2001/003435
Authority: WO
Inventors: Toshihiro Tatami; Tsuneo Matsudaira; Yasuo Suzuki; Tomohiro Yoshida; Yuichi Yamakawa
Original assignee: Nkk Corporation
Priority date: 2000-04-28
Filing date: 2001-04-23
Publication date: 2001-11-08
Also published as: JP2001300470A

Abstract

A fly ash treating method and a device therefor, in a waste gasification melting furnace capable of treating large amounts of fly ash without the provision of complicated devices and being simple to operate in treating. Fly ash collected at a dust collector and that collected at a boiler and a desuperheating tower are fed to a fly ash charging apparatus, and, as needed, fly ash produced in other waste treating apparatuses is received, to provide a pre-treating required before charging fly ash into a waste gasification melting furnace. In the fly ash charging apparatus, received fly ash is added with water to be turned into a sludge form, and the sludge-form fly ash is charged into the waste gasification melting furnace.

Description

Specification

Ash treatment method and apparatus

Translation field

The present invention relates to a method for treating fly ash that is scattered and collected from a furnace during heat treatment of waste, such as waste melting treatment, waste incineration treatment, or waste incineration residue melting treatment. And its device. Background

Of the residues from the incineration of waste, fly ash scattered from the incinerator and collected by dust collectors contains harmful metals. Therefore, the landfill must be treated to stabilize harmful metals. Waste incineration residues are mostly landfilled, but as it becomes more difficult to secure final disposal sites, it has become necessary to reduce the volume of incineration residues. For this reason, some incineration residues are melted. In addition, the development of technology for directly melting and combusting combustible waste and converting it to slag is also under way. As described above, the melting treatment of combustible waste or waste incineration residue (hereinafter simply referred to as either or both) means that volume reduction of waste and stabilization of heavy metals are achieved at the same time. Technology is attracting attention.

There are several methods for melting waste. As one of the methods, there is a method in which coke deposited in a furnace is burned to form a high-temperature combustion zone, and waste is charged and melted on the high-temperature coke layer. According to this method, in particular, a shaft furnace is used. The melting treatment of waste by the shaft furnace is performed as follows. That is, auxiliary materials such as coke and limestone are charged into the furnace together with waste, and a coke layer is formed at the bottom of the furnace. Then, air or oxygen-enriched air is blown into the coke layer to burn coke and form a high-temperature combustion zone. Meanwhile, waste is loaded on top of it. If the waste loaded contains flammable waste, the waste is pyrolyzed to produce flammable gas while being preheated on a hot coke bed. This combustible gas is burned by blowing air in the melting furnace or in the secondary combustion furnace, and is sent as a high-temperature gas to the heat recovery unit. Also, even if the charged waste is incineration residue, the high-temperature gas discharged from the melting furnace is sent to the heat recovery unit. The heat-recovered gas is sent to the dust collection process to remove dust (fly ash), and then sent to the harmful gas removal process to be purified and released.

On the other hand, the charged waste incineration residue ゃ the thermal decomposition residue of the waste descends and melts in the high-temperature combustion zone, becomes molten slag, drops through the coke layer, and collects at the furnace bottom and discharges it. Is done.

However, as described above, fly ash collected in dust collectors and the like is also discharged during waste melting treatment, so that treatment must be performed to stabilize harmful metals in the fly ash.

Conventionally, the following technologies have been proposed to solve the above-mentioned problems. Japanese Patent Application Laid-Open No. H11-110014 mentions that fly ash discharged from a waste melting furnace and collected in a gas treatment system is added with a component modifier such as lime powder or quartz powder. A method is disclosed in which after adjusting the basicity to a predetermined range, the fly ash is blown into a furnace from a tuyere provided at the lower part of the furnace to melt fly ash and discharged from the lower part of the furnace as molten slag.

Also, in Japanese Patent Application Laid-Open Nos. 7-2087-119 and 11-1417827, when fly ash is directly charged into a melting furnace, a large amount of fly ash is re-scattered. Therefore, a method to prevent fly ash from re-scattering is shown. In this method, water is added to dust generated in a waste melting furnace, granulated and solidified, then charged again into the above melting furnace, melted, and discharged as molten slag from the lower part of the furnace. Is the way. However, there is room for improvement in any of the above prior arts. In the method disclosed in Japanese Patent Application Laid-Open No. H11-110143, fly ash is blown into the lower part of a melting furnace maintained at a high temperature, so that most of the fly ash is quickly melted, and molten Discharged as lag. However, in this case, if the amount of fly ash blown exceeds a certain limit, the temperature around the tuyere into which the fly ash is blown drops to a level outside the allowable range. Then, the furnace condition at the bottom of the melting furnace becomes abnormal. This is because, compared to the case where fly ash is not blown, extra heat is required to heat the fly ash. Therefore, this method is suitable for treating a small amount of fly ash, and is unsuitable as a method for treating a large amount of fly ash.

Further, in this method, when fly ash is melted, the basicity of the fly ash to be blown must be adjusted so that the melt has an appropriate fluidity. This basicity adjustment is performed in order to make the melt of fly ash flow down smoothly. At this time, according to the fluctuation of the component composition of the fly ash collected and sent by the dust collector, an adjustment operation of adding an appropriate amount of lime powder or adding an appropriate amount of quartz powder must be performed successively. . Therefore, the operation for supplying fly ash to the melting furnace becomes very complicated.

In the method disclosed in Japanese Patent Application Laid-Open Nos. 7-2087-119 and 11-1141827, a device for granulating fly ash to be returned to the melting furnace is provided and its operation is controlled. The problem is that you have to do it. When granulating fly ash, it is necessary to take measures such as adjusting and changing the operating conditions of the granulating device sequentially according to the properties of the fly ash collected and sent by the dust collector. For this reason, in this method, a fly ash granulation device must be provided, and a lot of work such as condition adjustment operation and monitoring work occurs for the operation management, and the amount of work increases. Furthermore, since fly ash is mostly fine powder, measures must be taken to prevent the work environment from deteriorating due to dust generated during the granulation process.

Disclosure of the invention

SUMMARY OF THE INVENTION The present invention solves the above problems, and can treat a large amount of fly ash without having a complicated device, and a method for treating fly ash which is easy to treat and a method thereof. It is intended to provide a device.

That is, the method for treating fly ash according to the present invention comprises the steps of: adding heat to the fly ash scattered from the furnace when the waste is heat-treated to form sludge; and disposing the sludge-like fly ash. It is characterized by being charged into a material melting furnace. The fly ash treatment method is characterized in that the water added to make the fly ash into sludge is water in wastewater or waste with a high water content.

Further, the method for treating fly ash according to the present invention is characterized in that sludge-like fly ash is melted in a waste melting furnace and discharged as molten slag.

Further, the fly ash processing apparatus ′ in the present invention is provided with: a fly ash measuring and supplying means; a moisture measuring and supplying means; a kneading means for converting the supplied fly ash and moisture into a sludge state; It is characterized by having means for charging sludge-like fly ash into a waste melting furnace.

Further, the fly ash treatment apparatus of the present invention is characterized in that sludge fly ash is melted in a waste melting furnace and discharged as molten slag. In the above description, fly ash refers to dust that has been scattered and collected from the furnace during heat treatment of waste, and is generated when the waste is melted. Includes waste generated by incineration or waste generated by incineration residue melting. Therefore, fly ash that can be treated in the present invention is not limited to that generated from a waste melting furnace that treats the fly ash, but may be any other waste incineration equipment or waste melting equipment. It may be generated from In addition, fly ash generated from the waste melting furnace does not refer only to fly ash collected by the collector, but is collected by a poiler or cooling tower located between the melting furnace and the dust collector. This is a generic term that also includes dust that is produced.

When fly ash is charged from the upper part of the waste melting furnace and melted, if the fly ash is directly charged into the melting furnace, a large amount of fly ash will be re-scattered. Pre-processing is required. However, according to the study results of the present inventors, It has been found that the pretreatment does not necessarily have to employ a complicated method for granulating fly ash.

Therefore, in the present invention, when the fly ash is charged into the waste melting furnace, the fly ash is scattered before reaching the high temperature coke layer deposited at the lower part of the melting furnace. Perform pre-processing just to disable As a pre-treatment, the fly ash is made sludge-like by adding moisture to the fly ash, and the sludge-like fly ash is charged into a melting furnace.

(Here, 'sludge-like' means that fly ash is a muddy substance containing water to such an extent that it does not easily scatter during transportation or loading.) The only pretreatment of the fly ash that occurs is to simply turn the powder into mud. Therefore, the processing when charging fly ash into the melting furnace is extremely simple and easy.

Fly ash treatment is not performed by blowing into the lower part of the melting furnace, but by charging from the upper part of the melting furnace. Therefore, a desired amount of fly ash can be charged without affecting the high-temperature combustion zone at the lower part of the melting furnace. As a result, a large amount of fly ash can be treated, and fly ash generated in other waste treatment facilities can be accepted and treated. ,

In the present invention, water such as industrial water may be used as a water source for the pretreatment of turning fly ash into sludge. However, wastewater treatment facilities have wastewater (sewage) that must be treated by wastewater treatment equipment, and wastewater treatment equipment discharges waste such as sludge and sludge. Therefore, these wastewaters and wastes having a high moisture content may be added and kneaded. For this reason, according to the present invention, it is possible to perform not only the melting treatment of fly ash but also the treatment of secondary waste such as sewage and sludge.

When the sludge-like fly ash is charged into the melting furnace as described above, most of it falls onto the high-temperature coke layer deposited at the lower part of the melting furnace. Then, it is melted together with the waste residue and mixed into the slag, and is discharged as molten slag. However, in the process of heating the charged fly ash to a high temperature, some fly ash or components in the fly ash may be scattered. However, these materials are collected by a dust collector provided in a later process, re-charged into a melting furnace, and melted. It becomes a melt.

As described above, the present invention is a technology for charging and melting fly ash into a waste melting furnace for heat-treating waste, wherein the fly ash is charged after being pre-processed into sludge. It is characterized by the following. For this reason, the type of furnace into which the fly ash formed into sludge in the pretreatment is charged is not limited as long as the furnace can melt and discharge the fly ash.

In order to achieve the above object, the present invention discloses the following. That is,

• Fly ash treatment methods include:

A step of adding water to the fly ash to generate sludge-like fly ash; a step of charging the sludge-like fly ash into a waste melting furnace.

-Fly ash processing methods are as follows: '

A step of melting the sludge fly ash in a waste melting furnace; and a step of discharging the melted sludge fly ash as molten slag. • Fly ash processing equipment consists of:

Fly ash hopper for storing fly ash;

A fly ash metering / supplying means for measuring and extracting the fly ash from the fly ash hopper; measuring a water content of the measured fly ash; and supplying a water content to the measured fly ash. Supply means;

Kneading means for adding the water supplied from the moisture measuring and supplying means to the fly ash supplied from the fly ash measuring and supplying means to form a sludge; and kneading in the kneading means. A means for charging sludge fly ash into a waste melting furnace.

• Fly ash processing equipment consists of:

Means for melting the sludge fly ash in the waste melting furnace; and means for discharging the melted sludge fly ash as molten slag. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic diagram showing an example of an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of the configuration of the fly ash charging facility in FIG. FIG. 3 is a schematic diagram showing another example of the configuration of the fly ash charging facility in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is an explanatory diagram of an example according to an embodiment of the present invention. In the following description of Fig. 1, the case where the waste to be treated is combustible waste will be described.

Reference numeral 10 denotes a vertical and cylindrical waste melting furnace. Numeral 1 is a waste charging facility, and waste, coke, and limestone as a slag component modifier are charged to the melting furnace by this facility. Reference numeral 20 denotes fly ash charging equipment for receiving fly ash and charging it into the melting furnace 10. This equipment is usually for receiving fly ash collected in the gas treatment process and charging it into the melting furnace 10, but was collected at another waste treatment facility if necessary. Fly ash can also be accepted and processed. The configuration of the fly ash charging equipment 20 is shown in Fig. 2.

The lower part of the melting furnace 10 performs gasification of waste and melting treatment of residues, and the upper part whose diameter has been expanded is a free-pod part. 50 indicates a coke layer deposited on the bottom of the furnace, and 51 indicates a fluidized bed of waste. Reference numeral 12 denotes an outlet for combustion gas, and reference numeral 13 denotes an outlet for molten slag.

A main tuyere 14 for blowing air or oxygen-enriched air is provided at the lower part of the melting furnace 10 where the coke layer 50 is formed. Combustion zones are formed and waste residues are melted. At the position where the waste fluidized bed 51 is formed, a sub tuyere 15 for blowing air for flowing the waste is provided. 'Furthermore, a three-stage tuyere 16 for blowing air for burning the generated combustible gas is provided in the freeboard portion above the fluidized bed 51. · In the figure, 31 is a boiler that recovers the heat of the combustion gas discharged from the melting furnace. A cooling tower for cooling, 33 is a dust collector such as a bag filter, 34 is a draft fan, and 35 is a chimney. Fly ash collected by the dust collector 33 and fly ash collected by the boiler 31 and the cooling tower 32 are combined and sent to the fly ash charging facility 20.

The exhaust gas outlet, the boiler, the cooling tower and the dust collector are connected by an exhaust gas duct.

FIG. 2 is a diagram showing an example of the configuration of the fly ash charging facility in FIG. 21 is a fly ash hopper that receives fly ash collected in the gas treatment process. Reference numeral 22 denotes fly ash metering and supply means for extracting fly ash from the fly ash 21 while measuring the fly ash. In this embodiment, a rotary feeder is used. Reference numeral 23 denotes a closed powder carrier such as a screw conveyor. Reference numeral 24 denotes a means for measuring and supplying water for measuring water such as sewage generated in a waste treatment facility.In this embodiment, a flow indicator 25 and a valve 26 for setting a flow rate are used. I do. 27 is a kneading means for converting the supplied fly ash and moisture into sludge, and a paddle-type kneader or the like is used. Reference numeral 28 denotes fly ash charging means for charging sludge-like fly ash into the melting furnace 10. In this embodiment, a monopump suitable for transporting mud is used. Compressed air is injected at the inlet of sludge-like fly ash, so that sludge-like fly ash is dispersed and loaded in the lower part of the furnace. In the present invention, the fly ash is sludge-shaped so as to prevent fly ash charged into the melting furnace 10 from scattering before reaching the furnace lower part. The moisture content of the resulting fly ash does not have to be strictly controlled. For this reason, the equipment for measuring fly ash and water only needs to be able to measure almost quantitatively.

In the equipment consisting of Fig. 1 and Fig. 2, the melting treatment of waste is performed as follows. That is,

Waste, coke, and limestone are weighed and charged in predetermined quantities. Main wing Air or oxygen-enriched air is blown from the port 14 to burn the coke in the coke layer 50, forming a high-temperature combustion zone at the bottom of the furnace. Further, the waste stays on the coke layer 50 to form a fluidized bed 51, is preheated on the high-temperature coke layer 50, and is thermally decomposed into a combustible gas. The combustible gas is burned by blowing air from the three-stage tuyere 16 into high-temperature gas, discharged from the outlet 12 and sent to the gas treatment process.

During the operation where gasification and melting of waste is being performed as described above, in the fly ash charging facility 20, the fly ash stored in the fly ash hopper 21 is collected by the rotary feeder 22. It is cut out almost quantitatively and supplied to the kneading means (paddle type kneading machine) 27 by the screw conveyor 23. In addition, water such as sewage, which has been measured almost quantitatively by the water metering / supplying means 25, is co-supplied to the mixing means 27. The fly ash supplied to the kneading means 27 is kneaded into sludge, and is charged into the melting furnace 10 by the fly ash charging means (monopump) 28. Most of the fly ash charged into the melting furnace 10 falls onto the coke layer 50, melts and flows down together with the waste residue, and is discharged as molten slag.

On the other hand, the high-temperature gas discharged from the melting furnace 10 is sent to the boiler 31 for heat recovery. The exhaust gas from the boiler 31 is sprayed with water in a cooling tower 32, cooled rapidly, sent to a dust collector 33 for dust removal, and then emitted through a harmful gas removal device.

Fly ash scattered from the melting furnace 10 is collected by the dust collector 33, and the settled ash is also discharged from the boiler 31 and the cooling tower 32 upstream thereof. These fly ash are sent to the fly ash processing equipment 20 and recharged to the melting furnace 10 where they are melted.

The reloading of fly ash is repeated as described above. During this repetition process, in the process in which the fly ash charged into the melting furnace 10 is heated to a high temperature, some of the heavy metal compounds that are relatively easily vaporized in the components in the fly ash vaporize again. . Then, it is discharged together with newly generated fly ash. As a result, fly ash containing concentrated heavy metals is discharged. For this reason, operations to extract only a small amount of the collected fly ash are performed as appropriate. Since this fly ash contains a large amount of heavy metals such as zinc, it can be supplied for use as a raw material for manufacturing non-ferrous metals. Note that, in the above embodiment, a method is described in which the pretreated fly ash is charged into a shaft furnace type waste melting furnace and melted together with combustible waste. In addition, the present invention is not limited with respect to the type of furnace into which the pretreated fly ash is charged, the type of waste to be treated in the furnace, and the like. FIG. 3 is a diagram showing another example of the configuration of the fly ash charging facility. In FIG. 3, the fly ash measured by the measuring and supplying means 22 and the water measured by the moisture measuring and supplying means 24 are directly sent to the fly ash charging means 28, and the fly ash and the moisture are removed. The fly ash is charged into the melting furnace 10 while being kneaded in the fly ash charging means 28.

At the inlet of sludge-like fly ash, compressed air is injected to separate sludge-like fly ash into the lower part of the furnace so that it can be charged.

When such simplified fly ash charging equipment is used, the state of kneading of fly ash and water is inferior to that using the equipment shown in Fig. 2, and the kneaded material of fly ash is transferred to the melting furnace 10. Fly ash that re-scatters when it is loaded. However, the fly ash that has been re-scattered is re-charged and treated. Therefore, in a facility where the amount of fly ash processed is small, the advantage of simplifying the facility is greater.

According to the present invention, when fly ash is treated by a waste melting furnace, the fly ash can be melt-processed only by providing a simple pretreatment device that merely makes the fly ash sludge-like. In addition, since fly ash is treated by charging from the upper part of the melting furnace, a desired amount of fly ash can be charged without affecting the high-temperature combustion zone in the lower part of the melting furnace. For this reason, a large amount of fly ash can be treated, and fly ash generated in other waste treatment facilities can be accepted and treated. In addition, wastewater such as sewage and sludge can be used as a water source when pre-treating fly ash into sludge. It can also process secondary waste.

Claims

The scope of the claims

1. Fly ash treatment method is as follows:

Adding water to the fly ash to form sludge-like fly ash;

Charging the sludge fly ash into a waste melting furnace.

2. In the method according to claim 1, the water added to make the fly ash into sludge is water in waste having a high water content.

3. The method according to claim 1, wherein the boiler, the temperature reducer, and the dust collector are sequentially installed along the gas flow direction of the combustion exhaust gas discharged from the waste melting furnace and connected by an exhaust gas duct. At least one of the fly ash is collected and charged into the waste melting furnace.

4. In the method according to claim 1, the step of charging the sludge-like fly ash comprises: injecting compressed air from an upper portion to a lower portion of the waste melting furnace, so that the sludge fly ash is injected from an upper portion of the waste melting furnace. Charging the sludge-like fly ash into the lower part.

5. Fly ash treatment method consists of:

A step of melting the sludge fly ash in a waste melting furnace; and a step of discharging the melted sludge fly ash as molten slag.

6. The method according to claim 5, wherein the fly ash is melted together with at least one of the gasified waste residue and the slag component conditioner.

7. The method according to claim 5, wherein the waste melting furnace has a coke layer formed at a lower part in the furnace, and a fluidized bed formed at an upper part of the coke layer.

8. Fly ash processing equipment consists of:

Fly ash hopper for storing fly ash;

Kneading means for adding the water supplied from the moisture measuring and supplying means to the fly ash supplied from the fly ash measuring and supplying means to form sludge;

.. means for charging the sludge fly ash kneaded in the kneading means into a waste melting furnace.

9. The apparatus according to claim 8, wherein said charging means further comprises:

Means for injecting compressed air at the inlet of the sludge-like fly ash to blow the sludge-like fly ash from the upper part to the lower part of the waste melting furnace.

10. Fly ash processing equipment consists of:

Means for melting sludge fly ash in a waste melting furnace; and

Means for discharging the molten sludge fly ash as molten slag.

11. The apparatus according to claim 10, wherein the apparatus for treating fly ash further comprises:

Poilers, cooling towers, dust collectors, which are installed sequentially along the gas flow direction of the combustion exhaust gas discharged from the waste melting furnace;

The waste melting furnace and the poirer, the poirer and the cooling tower, the cooling tower and the dust collector are connected by an exhaust gas duct.