JP2000176229A - Treatment of fly ash and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method of fly ash from an ash fusing furnace or the like which is enhanced in peeling property of fly ash stuck to a bag filter, and a device therefore. SOLUTION: An electric charging device 21 is provided in the preceding stage of the bag filter 4, and electric charging is impressed to fly ash and a bag filter retainer 24, when the fly ash contained in exhaust gas 23 is collected with the bag filter 4. When fly ash particles 22 which are charged reach the bag filter 4, and the electric charging at the bag filter retainer 24 is controlled to plus by an electric charge controller (a rectifier) 25, plus-charged particles of the fly ash particles 22 become easy to be peeled off from the bag filter 4 by an electrical impulse force, (Fig. (a)). Thus, peeling performance of the fly ash particles 22 from the bag filter 4 is greatly enhanced compared to the conventional method, (Fig. (c)). Besides, in the case that the charged state of the fly ash particles 22 is controlled only at plus with the charge controller 25 like the case of Fig. (b), the peeling performance of the fly ash particles 22 from the bag filter 4 is further more enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating fly ash in a melting furnace for incinerated ash from municipal waste or industrial waste (hereinafter simply referred to as waste).

[0002]

2. Description of the Related Art Exhaust gas from refuse incinerators and ash melting furnaces contains not only HCl but also low-boiling heavy metals such as NaCl and KCl, low-boiling heavy metals such as lead (Pb) and cadmium (Cd), and dust. Have been. In order to prevent high-temperature corrosion of the material constituting the flue of the refuse incinerator or ash melting furnace by HCl and to collect dioxin,
Slaked lime is blown in at a low temperature of around 00 ° C to remove HCl from CaCl
Generally, a system is used in which the number is set to ₂ and collected by a bag filter.

[0003] Fig. 3 shows an example of a system in which a refuse incinerator and an incineration ash melting furnace currently implemented or planned are combined. In FIG. 3, the refuse is a fluidized bed refuse incinerator 1.
And incinerated in a fluidized bed. The exhaust gas and fly ash are sequentially cooled by the gas cooler 2 and the heat exchanger 3 and then collected by the bag filter 4. Slaked lime is blown into the flue gas from the slaked lime hopper 5 at the outlet of the heat exchanger 3 to remove HCl in the flue gas, and the flue gas that has been cleaned by the reaction of the following formula Ca (OH) ₂ + 2HCl → CaCl ₂ + 2H ₂ O The air is discharged from the chimney 7 by the induction blower 6.

The fly ash collected by the bag filter 4 is sent to a relay hopper 8 to be temporarily stored. When the ash is melted, a melting point depressant such as cullet is sent from the additive hopper 9 to the mixer 11 via the valve 10, where it mixes with the fly ash sent from the relay hopper 8 via the valve 12. Melting furnace 13
Will be introduced. In the melting furnace 13, the fly ash is melted and solidified.
Exhaust gas and fly ash from the melting furnace are supplied to gas cooler 2 and heat exchanger 3
And then collected by the bag filter 4. Slaked lime is blown from the slaked lime hopper 5 to remove HCl in the exhaust gas from the melting furnace, and the clean exhaust gas is discharged from the chimney 7 by the induction blower 6.

[0005] Fig. 3 shows an example in which the refuse incinerator 1 is of a fluidized bed type. In general, incineration ash and fly ash are sent to a melting furnace 13 to be melted and solidified. When the refuse incinerator 1 is of a fluidized bed type, there is no need to treat incineration ash, only melting of fly ash is required.

[0006]

Fly ash generated in a refuse incinerator has a higher chlorine (Cl) content than coal ash and the like, and the amount of Cl with respect to fly ash reaches as much as 10%. This Cl volatilizes in the form of HCl and chloride when molten, but NaCl, K
The rate of volatilization in the form of chloride such as Cl is as high as about 50%. That is, in a melting furnace of 20 t / day, 1 t / day of chloride (mainly NaCl, KCl) is generated. Until now, the treatment of the salt substitute was carried out by a large-sized wet desalination apparatus, but there was a problem that a large amount of industrial water had to be used (Japanese Patent Publication No. 6-22653).

Therefore, the present inventor has devised a dry type molten salt removing apparatus (Japanese Patent Application Laid-Open No. Hei 8-200642, Japanese Patent Application No. Hei 7-2006).
No. 167561) has a problem in terms of cost, and has attempted to improve the prior art. When the molten fly ash is collected with the bag filter in the conventional technology, the particle size of the molten fly ash is small and light, so as the melting time becomes longer, the bag filter gradually becomes clogged and recovered even if the bag filter is backwashed Otherwise, the bag filter was closed, and the operation of the melting furnace 13 had to be stopped. Further, when the bag filter is closed, the bag filter is extracted from the bag house, and the dust accumulated on the bag filter is removed and used. Therefore, there is a problem in terms of maintenance and maintenance costs. What is the problem of the present invention? An object of the present invention is to provide a fly ash treatment method and apparatus for an ash melting furnace or the like in which fly ash attached to a bag filter is improved in detachability.

[0008]

According to the present invention, in order to solve the above-mentioned problem, a charging device is provided in front of the bag filter, and when fly ash is collected by the bag filter, the fly ash and the bag filter retainer are provided. The above object can be achieved by providing a means for applying a charge to the ash and controlling the charge of the fly ash charged particles.

That is, according to the present invention, in a method for treating fly ash in exhaust gas discharged from an incinerator for a heatable substance containing solids, a bag filter for collecting fly ash is provided, and Fly ash treatment method for treating fly ash by applying charge to fly ash and controlling charge of fly ash particles, or fly ash in exhaust gas discharged from incinerator of heatable material containing solids In the processing device, a bag filter for collecting fly ash, a bag filter retainer for fixedly supporting the bag filter, and a charging device for applying a charge with fly ash are provided at a stage preceding the bag filter. It is an equipment for processing fly ash.

[0010]

A method of controlling the charge of fly ash charged particles by applying a charge to the fly ash and a bag filter retainer when collecting a fly ash with a bag filter by providing a charging device in an exhaust gas path in front of the bag filter. Are schematically shown in FIGS. 2A and 2B. FIG. 2C schematically shows the case of the conventional method.

In the case of FIG. 2C without the charging device 21, the fly ash particles 22 are sent to the bag filter 4 together with the exhaust gas 23 by the induction blower 6 and collected. Since the melting furnace fly ash has a small particle size and is light, it is laminated on the filter cloth of the bag filter 4. On the other hand, FIG. 2A in which the charging device 21 is provided.
In this case, the fly ash particles 22 reach the bag filter 4 in a charged state. At this time, bag filter retainer 2
When the electric charge of the fly ash particles 4 is controlled to be positive by the charge controller (rectifier) 25, the positively charged particles of the fly ash particles 22 are easily separated from the bag filter 4 by an electric repulsive force. For this reason, compared with the case of the conventional method of FIG.
The peeling performance from the bag filter 4 is greatly improved.

Further, when the charge state of the fly ash particles 22 is controlled to be positive only by the charge controller 25 as in the case of FIG.
The peeling performance from the surface can be improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a system configuration of a fly ash processing apparatus according to an embodiment of the present invention. This fly ash treatment apparatus is applied to a system in which the refuse incinerator 1 and the incineration ash 13 melting furnace shown in FIG.

Several tens of bag filters 4 are stored in the bag house 26. The bag filter 4 is fixed to a bag house 26 by a bag filter retainer (metal frame) 24. Exhaust gas 23 from the melting furnace 13 is sent from the flue to the baghouse 26 by the induction blower 6. At this time, fly ash is charged by the charging device 21 before the bag house 26 and sent to the bag house 26. The charged fly ash particles 22 are collected by the bag filter 4.

At this time, if the charge of the bag filter retainer 24 is controlled to be positive by the charge controller 25, the fly ash particles 2
The positively charged particles of No. 2 are easily separated from the bag filter 4 by the electric repulsion (see FIG. 2A). For this reason, the fly ash particles 2 are smaller than the conventional method shown in FIG.
The peeling performance of the second bag filter 4 from the bag filter 4 is greatly improved.
Further, when the charge state of the fly ash particles 22 is controlled to be positive only by the charge controller 25 as in the case of FIG. 2B, the performance of further separating the fly ash particles 22 from the bag filter 4 can be improved. Will be. In this way, the Na, Cl, and K components of fly ash in the exhaust gas are converted into N by the charging device.
a ⁺ , Cl ⁻ , and K ⁺ particles are collected by the bag filter 4. The exhaust gas thus cleaned is supplied to the induction blower 6
Purged from the chimney 7.

[0016]

According to the present invention, the bag filter can be prevented from being clogged, so that the cost during continuous operation can be reduced. Further, the maintenance of the bag filter is facilitated, and the maintenance cost is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a fly ash processing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic view of the operation of the fly ash processing apparatus of FIG. 1 and a conventional technique.

FIG. 3 is a diagram showing a flow of a system of a refuse incinerator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Garbage incinerator 2 Gas cooler 3 Heat exchanger 4 Bag filter 5 Slaked lime hopper 6 Induction blower 7 Chimney 8 Relay hopper 9 Additive hopper 10, 12 Valve 11 Mixer 13 Melting furnace 14 Slag hopper 21 Charging device 22 Fly ash particles 23 Exhaust gas 24 Bag filter retainer 25 Charge controller 26 Bag house

Continued on the front page (72) Inventor Naoki Fujiwara 3-36 Takaracho, Kure-shi, Hiroshima Prefecture Babcock Hitachi Kure Laboratory Co., Ltd. (72) Inventor Tsuneo Oku 1-2-10 Isogo Isogo-ku, Yokohama-shi, Kanagawa Babcock F-term in Hitachi Engineering Center Yokohama Co., Ltd. 4D058 JA04 KA08 KB05 MA60 QA01 QA30 SA20

Claims (6)

[Claims] 1. A method for treating fly ash in exhaust gas discharged from an incinerator of a heatable substance containing solids, comprising: a bag filter for collecting fly ash; A method for treating fly ash, comprising applying a charge and controlling the charge of the fly ash particles to treat the fly ash. 2. A bag filter retainer for fixing and supporting a bag filter, a positive and / or a negative charge is applied to fly ash between the bag filter retainer and a preceding stage of the bag filter, and the bag filter retainer is provided to the bag filter retainer. 2. The fly ash processing method according to claim 1, wherein the same charge as that of the fly ash particles is applied. 3. A melting furnace for melting and processing fly ash in the exhaust gas discharged from the incinerator and a bag filter for collecting the fly ash, a charge is applied to the fly ash at a stage preceding the bag filter, and The fly ash treatment method according to claim 1, wherein the fly ash discharged from the melting furnace is treated by controlling the charge of the fly ash particles. 4. A bag filter for collecting fly ash and a bag for fixing and supporting the fly ash in an apparatus for treating fly ash in exhaust gas discharged from an incinerator of a heatable substance containing solids. An apparatus for treating fly ash, comprising: a filter retainer; and a charging device for applying an electric charge with fly ash at a stage preceding the bag filter. 5. The fly ash processing device according to claim 4, further comprising a charge control device for controlling an amount of charge applied by the charging device. 6. A melting furnace for melting fly ash in exhaust gas discharged from an incinerator, a bag filter for collecting fly ash, a bag filter retainer for fixing and supporting the bag filter, and 5. The fly ash processing device according to claim 4, wherein a charging device for applying a charge with fly ash is provided at a stage preceding the bag filter, and the fly ash discharged from the melting furnace is treated.