JPH08200642A - Method and equipment for disposal of dust containing chloride in refuse-incineration disposal - Google Patents

Abstract

PURPOSE: To obtain a method for disposal of dust containing chloride in refuse incineration disposal which enables attainment of molten slag of excellent quality by removing beforehand the chloride contained in the dust at the time of the refuse incineration disposal. CONSTITUTION: While a chloride-containing gas exhausted from a refuse incinerator is cooled by gas coolers 3 and 5 and others, it is made to react with hydrated lime and then collected as dust by a bag filter and the dust is heated to 900-1100 deg.C in a decomposing furnace 101 so that chloride be expelled from the dust. The chloride-containing gas is introduced into a salt removing unit filled with a filler and, while the gas is cooled down to a prescribed temperature, the chloride in the gas is brought into contact with the filler and collected thereby. Then, the dust wherefrom the chloride is separated and removed is sent from the decomposing furnace to an ash melting furnace 19, melted therein and recovered as slag. On the other hand, the chloride-containing gas is treated with the hydrated lime and collected by a bag filter 28.

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 chloride-containing dust during incineration of garbage, and more particularly to a method and apparatus for treating chloride-containing dust contained in the soot dust of municipal waste incinerators. The present invention relates to a method and an apparatus for treating chloride-containing soot dust during garbage incineration, which is suitable for preventing clogging of flues and bag filters.

[0002]

[Prior Art] With the revision of the law in 1992, dust incinerator soot dust is designated as "specially controlled general waste", and intermediate treatment is required to dispose of soot dust. , Drug treatment and solvent extraction treatment 4
The method was specified. Among them, the melt solidification method can be said to be the most effective means because it can reduce the volume, has a high degree of stabilization, does not require chemicals, additives, etc., and has the possibility of effectively utilizing the molten slag. .

Up to now, the melting furnace has been mainly studied as a treatment of sewage sludge. Also in the field of municipal waste, development of a melting furnace for incineration ash or incineration ash and large-scale waste is being carried out, and it has already been tested in several local governments. Fig. 5 shows an example of a system that combines a refuse incinerator and an incinerator ash melting furnace. In FIG. 5, municipal solid waste is put into the solid waste incinerator 2 from the solid waste chute 1 and incinerated. The incinerator exhaust gas passes through the gas cooler 3, the air preheater 4, and the gas cooler 5, is cooled, and is sent to the flue 6. On the other hand, slaked lime is fed from the slaked lime hopper 7 to the flue 6 by the constant amount feeder 8 in order to remove HCl in the exhaust gas. The slaked lime sent into the flue 6 by the air blowing from the carrier air blowing pipe 9 reacts with HCl in the exhaust gas to become CaCl ₂ . Unreacted and reacted slaked lime are collected by the bag filter 10 together with soot dust. The thus-cleaned exhaust gas is sent to the chimney 12 by the induced air blower 11 and discharged into the atmosphere.

In order to improve the combustion state by stirring the fluid medium of the refuse incinerator 2, air is blown in by the blower 13 and the valve 14
And the amount of primary and secondary air is adjusted by the valve 15 and the incinerator 2
Burn the garbage completely with. The dust collected by the bag filter 10 passes from the relay hopper 17 via the valve 16 to the ash transport pipe 1
It is sent to the melting and solidifying furnace 19 via 8. The soot dust is melted here by the heavy oil burner 20, and the generated molten slag falls from the slag tap 21 to the slag hopper 22 and is collected.
The exhaust gas of the melting and solidifying furnace 19 passes through the gas cooler 23, the air preheater 24, and the gas cooler 25, and then is sent to the flue 26. Slaked lime is blown from the valve 27 for dechlorination and is collected together with soot and dust by the bag filter 28. The clean exhaust gas is discharged from the chimney 30 into the atmosphere by the induction blower 29. Air is sent to the melting and solidifying furnace 19 by the blower 31 to improve the combustion state of the heavy oil burner 20. The soot and dust collected by the bag filter 28 is temporarily stored in the relay hopper 32 and then sent to the ash stabilizer 34 via the valve 33. Here, the medicine is supplied from the medicine supply pipe 35 and stabilized.
The detoxified soot and dust is extracted from the discharge pipe 36 and landfilled. Although FIG. 5 shows the case where the incinerator is of the fluidized bed type, generally, incinerator ash and soot dust are sent to the melting furnace to be melted and solidified. When the incinerator is a fluidized bed type, it is not necessary to treat the incineration ash, and only the soot dust melting treatment is required.

[0005]

[Problems to be Solved by the Invention] Waste incinerator 80
When heated to 0 to 1000 ℃, chloride (NaC
1, KCl, etc.) evaporate. If this chloride is mixed in the molten slag, there is a problem that the strength of the slag decreases. In order to obtain high quality molten slag, we are studying a method of preheating soot dust to about 1100 ° C in a decomposition furnace, expelling chloride in the dust and melting clean ash. When exhaust gas is passed through a bag filter, chlorides may be attached and cause clogging immediately. In addition, the decomposition furnace exhaust gas is cooled and sent to the bag filter, but the temperature is the melting point of the molten salt (about 800 ~
When the temperature is lower than 900 ° C., chloride is condensed in the flue, and there is a problem that the flue becomes blocked with time. Waste incinerator soot dust has a higher Cl content than coal ash, and the amount of Cl to soot dust is as high as 10%. This Cl volatilizes in the form of HCl and chloride when melted, but NaCl, KC
The rate of volatilization in the chloride form such as 1 is about 50%.
That is, chloride (mainly NaCl, KCl) is produced in a melting furnace of 20 t / day at 1 t / day. Up to now, a large-scale wet desalting apparatus has been used, but there is a problem because a large amount of industrial water is used (Japanese Patent Publication No. 6-22653).

An object of the present invention is to solve the above-mentioned problems of the prior art and to treat chloride contained in soot dust in exhaust gas discharged from a refuse incinerator by a simple dry method. To provide a method and an apparatus for treating chloride-containing dust.

[0007]

In order to achieve the above object, the invention claimed in the present application is as follows. (1) In the method for treating chloride-containing dust during garbage incineration treatment, in which dust (dust) containing chlorine (Cl) components from the refuse incinerator is collected by a bag filter and then solidified by melting, it is collected by the bag filter. Desalination device in which soot dust is decomposed in a decomposition furnace to volatilize and separate chlorides in soot dust, and a filler is filled while the exhaust gas at the decomposition furnace outlet containing the volatilized and separated chlorides is kept at a melting point of chloride or higher. Introduced into, to remove and remove salt by contacting with the filler at a temperature below the temperature at which the chloride is almost completely condensed, and melting and solidifying the soot dust from the decomposition furnace from which chloride has been separated in a melting and solidifying furnace. A characteristic method for treating chloride-containing dust during incineration of refuse.

(2) In (1), the method for treating chloride-containing dust during refuse incineration treatment is characterized in that the exhaust gas inlet temperature of the salt removing device is 800 ° C. or higher and the outlet temperature is 600 ° C. or lower. . (3) A dust collector that collects soot dust containing chlorine (Cl) component in the combustion exhaust gas discharged from the waste incinerator, and a melting and solidifying device that heats and solidifies the collected soot dust In a device for treating chloride-containing dust during refuse incineration, a decomposition furnace that decomposes the chloride in the dust and expels it as gas before treating the collected dust with a melting and solidifying device, and the exhaust gas from the decomposition furnace A treatment device for chloride-containing dust during refuse incineration treatment, comprising a salt removal device for collecting chloride and a melting and solidifying device for melting and solidifying soot dust processed in a decomposition furnace.

(4) In (3), the desalting device is a desalting device filled with a filler that contacts exhaust gas and collects chloride in the exhaust gas. Chloride-containing dust treatment device.

[0010]

The soot and dust were formed into a columnar shape by an extruder having a diameter of 6 mm and dried at 180 ° C. for 2 hours. 50 g of each of the soot dust granules at 900, 1000 and 1100 ° C. respectively.
It was heated and baked for hr. FIG. 2 shows the change in sample composition with respect to the firing temperature. It can be seen from FIG. 2 that the volatile elements are mainly Cl, K, and Na when the soot dust is heated and fired at 900 to 1100 ° C. It was revealed that the S content did not volatilize up to 1100 ° C. The vaporization rate of Cl at 1100 ° C is 85
%, And the volatilization rates of K and Na are 97 and 99%, respectively. From this, it is considered that Cl mainly volatilizes in the form of a molten salt of NaCl and KCl. Since the melting points of NaCl and KCl are 801 and 770 ° C., respectively, they condense and solidify at temperatures lower than this temperature. In order to prevent clogging of the flue, the inlet temperature of the salt remover must be 800 ° C or higher, preferably 900 ° C or higher. In some cases, a method may be considered in which the exhaust port of the cracking furnace is directly connected to the inlet of the salt remover. The outlet temperature of the demineralizer may be a temperature at which the chloride is almost completely condensed,
The temperature is maintained at 600 to 500 ° C or lower. In this way, the soot dust from the refuse incinerator is processed in the decomposition furnace before being melted and solidified, and a small dry desalting device is installed between the exhaust line of the decomposition furnace and the bag filter to preliminarily remove chloride such as KCl and NaCl. By removing the objects, it is possible to prevent clogging of the flue and clogging of the bag filter.

[0011]

EXAMPLE An example of the present invention will be described with reference to FIG. The soot and dust generated from the refuse incinerator 2 is collected by the bag filter 10 and temporarily stored in the relay hopper 17. Then, it is sent to the decomposition furnace 101 by the ash carrier pipe 18 via the valve 16. The soot is decomposed here by heating at 900 to 1100 ° C. The decomposed soot dust is sent to the ash melting and solidifying furnace 19 and the heavy oil burner 20
Is melted and solidified. It is also conceivable to granulate the pellets into spherical or cylindrical pellets with a granulator and then decompose them in a decomposition furnace to prevent soot dust.

On the other hand, the exhaust gas generated from the decomposition furnace 101 is guided to the salt remover 102, where chlorides such as NaCl and KCl are collected. At this time, the decomposition furnace 101 and the salt remover 10
In order to prevent chloride from condensing in the flue connecting the two, the inlet temperature of the salt remover 102 is maintained at, for example, 900 ° C. or higher, and air is blown from the cooling air blowing pipe 103 to remove the salt remover 10.
The outlet temperature of 2 is maintained at, for example, 500 ° C. or lower. The exhaust gas from which the chloride has been removed by the salt remover 102 is the flue 26.
And is sent to the bag filter 28. The chloride collected by the salt remover 102 is discharged through the discharge pipe 104. Figure 5 shows the treatment of HCl and soot in exhaust gas from incinerators and melting furnaces.
This is similar to the conventional flow of. In FIG. 1, blowers 13 and 31 for injecting air, induced blowers 11 and 29 and chimneys 12 and 3 for clean exhaust gas purging.
0 is installed separately for each incinerator and melting furnace, but by installing them all together, the cost of equipment can be reduced.

Next, a concrete example of the salt remover 102 is shown in FIG.
FIG. 3 (1) shows a dry type chloride removing device, in which a small cylindrical or rectangular container is filled with (a) ceramic balls 105 or Raschig rings, (b) cylindrical monosys 10
6 or a tube filled with a thin tube, (c) plate-shaped partition plate 107
Or (d) the grid partition plate 108 is attached. The filling is made of refractory ceramic. Cooling air is blown into an effective position of the salt remover 102, and the temperature is controlled so that the temperature of the filling material becomes 500 ° C. or lower. Molten salts (NaCl, KCl) in the exhaust gas are cooled and adhere to the filler such as ceramic balls. If the amount of attached chloride increases, the exhaust gas becomes difficult to flow, and the salt remover 102 eventually closes. Therefore, the salt remover 102
It is necessary to detect the blockage condition of No. 2 with a differential pressure gauge, and when the pressure becomes a constant pressure, vibrate the entire device to separate chlorides and discharge them from the salt removal machine 102. For this reason, both ends of the device have a bellows structure 109 made of ceramic. Thus, the chloride adhering to the packing is separated from the packing by a mechanical shaking and scraping method. In the case of FIG. 3 (a), a structure in which a partition plate 110 in the shape of a plate is attached as shown in FIG. 3 (2), the filler is filled in the upper part, and the attached chloride is scraped off by vibration and collected in the lower part is also considered. To be The chloride thus desalted is discharged from the lower discharge pipe 104. As a salt removal method of the salt remover, a rotation method in which the filling is rotated and rubbed with a brush can be considered in addition to the vibration method shown in FIG.

A fluidized bed desalting system as shown in FIG. 4 is also conceivable. In FIG. 4, the cracking furnace exhaust gas has an inlet temperature of 90.
It is guided to the fluidized bed demineralizer 102 at 0 ° C. or higher. Normally, sand having a particle size of 0.5 to 1.5 mm is used as the fluid medium 111 of the fluidized bed, and limestone is mixed with the sand so that HCl can be removed together. The fluidized medium 111 is cooled by blowing air from the cooling air blowing pipe 103 to control the outlet temperature of the salt remover to 500 ° C. or lower. Since the internal temperature changes in accordance with the height of the fluidized bed and the change in the flow rate of exhaust gas, the outlet temperature is detected by a detector and the cooling air amount is controlled according to that value. The chloride adhering to the fluid medium in the fluidized bed is collected in the separator 113 via the valve 112 and separated into chloride and fluid medium. The fluidized medium is sent to the fluidized bed of the desalting machine and circulated by the fluidized medium circulation line 114. The fluid medium scattered from the fluidized bed is collected by the cyclone 116. Then, the chloride discharge line 11 via the valve 117.
Sent to 5. HCl in the exhaust gas due to limestone in the fluidized bed
Is also removed as CaCl ₂ . That is, in the case of this method, it is necessary to combine HC with chlorides such as NaCl and KCl.
l is also removed. Therefore, the exhaust gas from the cyclone 116 becomes cleaner than that in the case of FIG. 3 and is sent to the exhaust system. Chloride separated in the separator 113 is sent from the chloride discharge line 115 to the ash stabilizer 34 via the valve 33, where it is stabilized by the chemical from the chemical supply pipe 35 and discharged in the exhaust pipe 36. . Dry salt removal by such a method eliminates the need for a large wet wet salt treatment facility and reduces the construction cost.

[0015]

According to the present invention, chloride-containing soot dust in combustion exhaust gas discharged from a refuse incinerator can be efficiently treated while preventing clogging of a flue and clogging of a bag filter. Moreover, since it is a dry type, the device is compact and advantageous in terms of utility.

[Brief description of drawings]

FIG. 1 is a flow chart of an embodiment in which a salt removing device is provided between a cracking furnace exhaust gas line and a bag filter according to the present invention.

FIG. 2 is a view showing a composition change of a sample at a firing temperature.

FIG. 3 is a diagram showing a specific example of a salt remover.

FIG. 4 is a diagram showing a specific example of a salt remover.

FIG. 5 is a flow diagram of a conventional waste incinerator.

[Explanation of symbols]

1 ... refuse input chute, 2 ... refuse incinerator, 3 ... gas cooler, 4 ... air preheater, 5 ... gas cooler, 6 ... flue, 7 ...
Slaked lime hopper, 8 ... fixed quantity feeder, 9 ... carrier air blowing pipe,
10 ... Bug filter, 11 ... Induction blower, 12 ... Chimney,
13 ... Blower, 14 ... Valve, 15 ... Valve, 16 ... Valve, 17 ...
Relay hopper, 18 ... Ash carrier pipe, 19 ... Ash melting and solidifying furnace, 2
0 ... Heavy oil burner, 21 ... Slag tap, 22 ... Slag hopper, 23 ... Gas cooler, 24 ... Air preheater, 25 ... Gas cooler, 26 ... Flue, 27 ... Valve, 28 ... Bag filter, 29 ... Induction blower, 30 ... Chimney , 31 ... Blower, 3
2 ... Relay hopper, 33 ... Valve, 34 ... Ash stabilizer, 35
... chemical supply pipe, 36 ... discharge pipe, 101 ... decomposition furnace, 102
… Salt remover, 103… cooling air blowing pipe, 104… discharging pipe,
105 ... Ceramic ball, 106 ... Cylindrical monosis,
107 ... Plate-shaped partition plate, 108 ... Lattice-shaped partition plate, 109 ...
Ceramic bellows, 110 ... Drain, 111 ... Fluid medium, 112 ... Valve, 113 ... Separator, 114 ... Fluid medium circulation line, 115 ... Chloride discharge line, 116 ... Cyclone, 117 ... Valve.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toru Sente 1-2-10, Isogo-ku, Yokohama-shi, Kanagawa Babcock-Hitachi Kure Factory Yokohama Engineering Center

Claims (4)

[Claims] 1. A method for treating chloride-containing dust in a refuse incineration process, wherein the dust (dust) containing chlorine (Cl) component from a refuse incinerator is collected by a bag filter and then solidified by melting. The collected dust is decomposed in a decomposition furnace to volatilize and separate the chloride in the dust, and the exhaust gas from the decomposition furnace that contains the volatilized and separated chloride is discharged while being filled with the filler while keeping the exhaust gas at the melting point of chloride or higher. It is introduced into a salt device, discharged and desalted by contacting with the filler at a temperature below the temperature at which chloride is almost completely condensed, and the soot dust from the decomposition furnace from which chloride has been separated is melted and solidified in a melting and solidification furnace. A method for treating chloride-containing dust during incineration of refuse, which is characterized by the above. 2. The method for treating chloride-containing dust in a refuse incineration process according to claim 1, wherein the exhaust gas inlet temperature of the salt removing device is 800 ° C. or higher and the outlet temperature is 600 ° C. or lower. 3. A dust collector for collecting soot dust containing chlorine (Cl) component in the combustion exhaust gas discharged from the refuse incinerator, and a melting and solidifying device for heating and solidifying the collected soot dust. In a device for treating chloride-containing soot dust at the time of waste incineration treatment provided, a decomposition furnace for decomposing chloride in the soot dust as a gas before processing the collected soot dust in a melting and solidifying device, and exhaust gas from the decomposition furnace A treatment device for chloride-containing dust during refuse incineration treatment, which is provided with a desalting device for collecting chloride in the inside and a melting and solidifying device for melting and solidifying soot dust treated in a decomposition furnace. 4. The chlorination process for refuse incineration according to claim 3, wherein the demineralization device is a demineralization device filled with a filler that contacts exhaust gas and collects chloride in the exhaust gas. Equipment for processing dust and soot.