JP2962783B2 - Dust collection and solidification of fluidized bed municipal solid waste incinerator fly ash - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for collecting and solidifying fly ash entrained in combustion exhaust gas generated when incinerating municipal solid waste in a fluidized bed furnace. .

[Conventional technology]

In a fluidized-bed municipal solid waste incinerator, it looks like boiling water
Garbage is put into the fluidized sand heated to 600-800 ° C, and is completely incinerated while being mixed and agitated.Therefore, most of the incineration residue taken out from the furnace bottom is iron chips, glass chips, and rubble. There is no problem in the processing and disposal of On the other hand, those with a high sedimentation velocity due to the sufficient height at the freeboard part of the fluidized-bed furnace (for example, bottle caps and canned lids) return to the fluidized bed again without reaching the furnace outlet, forming a flue gas stream. Fly ash riding out of the furnace has a particle end velocity lower than that of the flue gas stream, and has a particle diameter of about 200 microns or less, and does not include foreign matters such as iron chips, glass chips, and rubble. When this fly ash is solidified by a melting method or a sintering method for effective use, it has a high melting point and does not contain any iron swarf which may interfere with these operations, and has a particle size of 5 microns or more.
Because it is as fine as 200 microns or less and does not contain foreign matter,
There is an advantage that complicated removal steps are not required.

However, this fly ash has been collectively collected by an electric dust collector or the like as shown in FIG. 2 so that it is likely to be volatilized in the furnace and condensed and solidified in a low-temperature part such as a dust collector at a later stage.
Heavy metals such as Cd, Po, and Cu, and salts such as KCl and NaCl were contained in large amounts.

[Problems to be solved by the invention]

When the fly ash collected by the above-mentioned electric precipitator is heated to a high temperature of about 1200 ° C. in order to solidify the fly ash by a melting method or a sintering method, heavy metals and salts are volatilized again, and exhaust gas treatment of the melting furnace and the sintering furnace is performed. Not only is it necessary, but also the damage of the furnace material due to the volatilized salts and the obstruction due to the adhesion to the flue have become a problem.

Therefore, the present invention solves the above-described problems, and selectively collects fly ash containing no heavy metals or salts and solidifies it into a solid material that can be effectively used. An object of the present invention is to provide a method for collecting and solidifying ash.

[Means for solving the problem]

In order to solve the above problems, in the present invention, the fluidized bed municipal solid waste incinerator fly ash is used after the exit of the fluidized bed municipal solid waste incinerator.
Provide an inertial dust collector in a temperature range of 700 ° C or higher to collect dust, and heat-solidify the collected fly ash from a fluidized bed municipal incinerator at a temperature of at least 1000 ° C by a melting method or a sintering method. This is a method for solidifying fly ash from a fluidized bed municipal solid waste incinerator.

 Next, the present invention will be described with reference to the drawings.

FIG. 1 shows the present invention in the form of a process chart. Municipal solid waste is burned in a fluidized bed incinerator, discharged as a combustion gas containing incinerated ash from the incinerator outlet, collected by an inertial dust collector such as a cyclone provided in a high temperature range of 700 ° C or higher, and fly. Ash is collected and stored in an ash storage tank. On the other hand, the combustion gas containing incinerated ash that is not collected by the inertial dust collector, the gas temperature is reduced in the waste heat boiler or the small injection chamber, and further collected by the electric dust collector or the bag filter,
It is discharged from the chimney by an induction blower.

As described above, in the present invention, an inertial dust collector such as a cyclone is incorporated in the above-mentioned temperature range of the conventional exhaust gas treatment system, and the collected ash is separated and stored from the dust collector collected in the subsequent stage.
Then, the collected ash is subjected to a heat treatment at 1000 ° C. or more to be solidified.

[Action]

According to the present invention, when the fluidized bed municipal solid waste incinerator fly ash is solidified by a heat treatment of at least 1000 ° C. in a melting method or a sintering method, inertia such as a cyclone is applied to a high temperature region of 700 ° C. or more after the incinerator outlet. A dust collector is installed, and heavy metals such as Cd, Pb, Cu, etc.
When salts such as KCl and NaCl are volatilized as chlorides, and since these chlorides have a small particle size even in the solid state and are difficult to be collected by an inertial dust collector such as a cyclone, heavy metals such as Cd, Pb, Cu Fly ash which contains almost no salts such as KCl, NaCl, etc. is selectively collected, and the collected ash is solidified by a melting method or a sintering method without the conventional problems to achieve effective use. It is a low temperature range dust collector, and heavy metals such as Cd, Pb, Cu and KC
Fly ash in which salts such as l and NaCl are concentrated is separately treated by a cement solidification method or the like.

In other words, in view of the recent depletion of landfill sites (reclaimed land), sintering and solidification of incinerated ash by the sintering and melting methods calls for the effective use of raw materials for ceramics and roadbed materials. Fluidized bed fly ash is provided by the dust collection method of a fluidized bed municipal solid waste incinerator.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.

Example 1 In accordance with the process diagram of FIG. 1, a test was conducted in which municipal solid waste was incinerated using a facility in which a single-stage cyclone in which a refractory caster was struck at the outlet of the municipal solid waste fluidized bed incinerator was installed. Table 1 shows the amount of collected ash and the amount of ash collected in the remaining low-temperature part (collected ash collected by the electric dust collector) and the operating conditions.

Table 1 shows that about 5% of the total amount of fly ash per garbage weight is generated, about 80% of which is collected by the cyclone and about 20%
Is the trapped ash in the remaining low-temperature part.

Example 2 The ash collected in a municipal solid waste fluidized bed sintering furnace was chemically analyzed. Table 2 shows the results. In Table-2, the ash collected in the cyclone and the ash collected in the remaining low temperature part (the ash collected in the electric dust collector) are the ash collected from the municipal solid waste fluidized bed incinerator facility of Example 1, and Collected ash from an electric dust collector at another municipal solid waste fluidized bed incinerator facility.

From Table 2, comparing the collected ash from the cyclone and the collected ash in the remaining low-temperature part, the elements that become ceramic components such as Ca, Mg, Si, Al, and Fe are contained in the cyclone collected ash, and Cl, S, Cu , Pb, C
Elements that are easily volatilized, such as d and Zn, are contained abundantly in the remaining collected ash in the low-temperature part. The most volatile elements such as Hg, As, etc. are hardly contained in the cyclone trapping ash.

Since the collective ash has a different incineration equipment configuration, it has an intermediate composition between both the cyclone-collected ash and the remaining low-temperature collected ash.

Example 3 Various collected ashes described in Table 2 were subjected to melting and sintering tests using an electric furnace. FIG. 3 shows a schematic sectional view of the experimental apparatus used for this test. In FIG.
1 is an electric furnace, 2 is a magnetic dish, 3 is a cooling air intake, 4 is a bag filter, 5 is a scrubber, and 6 is a pump. The following test was performed using this apparatus. Table 3 shows the results.

Operation-1 Collect 100 g of cyclone collected ash on a magnetic dish,
It was placed in an experimental furnace and heated and melted at 1400 ° C. Volatile salt and heavy metal dust was collected with a bag filter. The generated acid gas was absorbed by a washing scrubber after the bag filter. After melting, the dust collected by the bag filter and the scrubber absorption liquid were subjected to chemical analysis, and the volatility of each element of the cyclone collected ash is shown in Table-3.

Operation-2 100 g of collectively collected ash was collected in a magnetic dish, placed in an experimental furnace, and heated and melted at 1400 ° C. Hereinafter, it carried out similarly to operation-1.

Operation-3 30g of water in 100g of collected ash and 100g of clay
After kneading and drying, collect it on a magnetic dish and place it in a laboratory furnace.
It was heated to 00 ° C and sintered. Volatile salt and heavy metal dust was collected with a bag filter. The generated acid gas and the like were washed with water after the bag filter and absorbed by a scrubber. After melting, the dust collected by the bag filter and the scrubber absorption liquid were subjected to chemical analysis, and the volatility of each element of the cyclone collected ash is shown in Table-3.

Operation-4 The same operation as in Operation-3 was performed on 100 g of the collected ash.

Elements that are more volatile than Table 3 are Na, K, Cl, Cu, Pb, Cd, Zn,
It was found that they were Hg and As. The volatility is higher in the melting method with a higher operating temperature than in the sintering method.

The dust collected by the bag filter, which volatilized at high temperature and solidified again at low temperature, was melted compared to the conventional batch ash in the case of the high-temperature treatment of the cyclone collected ash of this patent.
2.6 ≒ 0.1, 0.8 / 5.9 ≒ 0.14 in the case of sintering, 10-15%, confirming the validity of this patent.

Also, Cl in fly ash, which is an acid gas of HCl, is 0.3% in the case of the present patent from Table 2 and 5.2% in the case of the collective ash from this patent. In case of melting treatment compared to conventional collective ash (0.3 × 0.32)
÷ (5.2 × 0.36) = 0.05 (0.3 × 0.34) ÷ (5.2 × 0.49) = 0.
04 and only 4-5% confirmed the validity of this patent as well.

FIG. 4 shows an example of the particle size distribution of fly ash in a fluidized bed municipal solid waste incinerator. In the embodiment, one cyclone is installed in series at a temperature range of 700 ° C. or more.However, by installing a plurality of cyclones with a small outer cylinder in parallel at a temperature range of 700 ° C. or more, the separation limit particle diameter becomes smaller. The collection efficiency increases. In this case, the ratio of fly ash that is optimal for the heat treatment of the melting method and the sintering method in the entire fly ash increases, and therefore, the fly ash that is effectively used increases and the volume is further reduced. It is obvious.

〔The invention's effect〕

According to the present invention, heavy metals such as Cd, Pb, Cu and KCl, NaCl
Fly ash that contains almost no salts such as can be collected,
When the collected fly ash is solidified at a high temperature, problems due to volatilization of heavy metals and salts can be eliminated.

[Brief description of the drawings]

FIG. 1 is a process diagram showing a dust collecting method of the present invention, and FIG.
FIG. 3 is a process diagram showing a conventional dust collection method, FIG. 3 is a schematic sectional view showing an experimental apparatus of Example 3, and FIG. 4 is a graph showing a particle size distribution of fly ash from a refuse incinerator. 1 ... electric furnace, 2 ... magnetic plate, 3 ... cooling air intake,
4 Bag filter, 5 Scrubber, 6 Pump

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-55316 (JP, A) JP-A-58-95575 (JP, A) JP-A-54-161583 (JP, A) JP-A-59-55158 132931 (JP, A) JP-A-55-102812 (JP, A) JP-A-60-38079 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B09B 3/00 B04C 9 / 00 B01D 50/00 F23J 15/00 F23G 5/44

Claims (1)

(57) [Claims] A fluidized-bed municipal incinerator in which the fly ash from a fluidized-bed municipal incinerator is collected by installing an inertial dust collector in a temperature range of 700 ° C. or higher after the outlet of the fluidized-bed municipal incinerator. A method for solidifying fly ash in a fluidized-bed municipal solid waste incinerator, wherein the fly ash is heated and solidified at a temperature of at least 1000 ° C. by a melting method or a sintering method.