JPH10185154A - Method for treating industrial waste including sludge by fluidized bed type incinerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating industrial waste including sludge by a fluidized bed type incinerator in which the industrial waste including alkali components such as Na, K can be continuously treated and the operating efficiency of the furnace can be improved. SOLUTION: According to a method for treating industrial waste including sludge by a fluidized bed type incinerator 1 having a fluidized bed in a hearth 10b, the sludge is supplied to a furnace main body from the upper part 10d of the furnace main body and the furnace main body is heated by a burner 16 provided in the lower part thereof. Then, a fluidized bed is formed with solid materials and/or residue thereof included in the sludge in the hearth 10b. Then, air is supplied from a part below the aggregation of the solid materials and/or the residue thereof included in the sludge forming the fludized bed to fluidize the aggregation of the solid materials and/or the residue thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a method for treating industrial waste containing sludge by a fluidized bed incinerator having a fluidized bed in the hearth, and more particularly to a method for forming waste in a furnace hearth. Fluidized bed incinerator in which solids contained in sludge and / or residues thereof are used instead of heated silica sand (quartz sand whose main component is silicon dioxide: SiO2) as a fluidized bed to be heated The present invention relates to a method for treating industrial waste including sludge by the method.

[0002] Industrial waste that can be treated in the present invention includes at least a scrubber cleaning solution generated in a factory,
These include factory wastewater such as plating wastewater, activated sludge such as sewage sludge containing various organic substances, and waste plastic containing various plastics such as polyethylene and acrylic.

[0003]

2. Description of the Related Art Conventionally, fluidized bed incinerators have been used to treat municipal solid waste. There are two types of fluidized bed incinerators, a square type and a cylindrical type. In each case, a fluidized bed is formed at the lower part of the furnace body. Silica sand constituting the fluidized bed is introduced into the furnace body from above the furnace body, and is deposited on the furnace floor. Air is blown from below the hearth to form a fluidized bed made of silica sand. The fluidized bed is maintained at a high temperature of about 650 ° C. by burning heavy oil supplied into the furnace main body from a heavy oil burner arranged at a lower part of the furnace main body.

[0004] Municipal solid waste is introduced into the upper part of the fluidized bed using a rotary feeder or the like and burned. The waste gas in the furnace main body is discharged from the upper part of the furnace main body to a conventionally known exhaust gas treatment facility for processing. Further, incombustibles and ash are continuously taken out from the furnace bottom. A part of the silica sand forming the fluidized bed is also taken out of the furnace bottom together with them, but this silica sand is separated, returned to the furnace body again for the fluidized bed, and reused.

[0005]

As described above, the conventional fluidized bed incinerator is designed as an incinerator for municipal solid waste, and is used to remove industrial waste, especially washing liquid and plating waste liquid generated in factories. Not suitable for treating activated sludge such as industrial effluent, sewage sludge.

That is, when sludge from sewage or the like is introduced into a conventional fluidized bed incinerator instead of municipal waste, the sludge solidifies at the bottom of the furnace, and it is difficult to perform sufficient treatment. Alkaline components such as Na and K in the waste liquid are in a viscous molten state at a low temperature, stay in a low temperature region below the furnace, and are difficult to discharge out of the furnace. In particular, when silica sand is used as the material of the fluidized bed, it has a defect that it is bonded to the silica sand and adheres to the furnace wall, and continuous removal from the furnace bottom is impossible. Therefore, conventionally, it has been necessary to stop the operation of the furnace about once every 10 days and perform an operation of removing these. This operation required about 1 to 2 days, and took more than 3 days including reheating of the furnace, which significantly reduced the operation efficiency of the furnace.

When silica sand is used as the fluidized bed, there is a disadvantage that the flow rate of air blown from below is inevitably increased in order to form a stable fluidized bed. Similarly, the collected and cooled silica sand is continuously returned to the furnace body and reused, but the fuel (regenerated oil or heavy oil) for heating this silica sand has also increased, and improvements in this regard have been required. .

According to the present invention, industrial waste containing alkaline components such as Na and K can be continuously processed, thereby improving the operation efficiency of the furnace. An object of the present invention is to provide a method for treating waste.

Another object of the present invention is to provide a method for treating industrial waste including sludge by a fluidized bed incinerator, which can drastically reduce the energy consumption required for operating the furnace.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is a method for treating industrial waste containing sludge by a fluidized bed incinerator having a fluidized bed in a hearth section. Supplying sludge into the furnace main body from the upper part of the furnace main body, heating the furnace main body by a burner provided at the lower part of the furnace main body, and solid and / or residue contained in the sludge. The step of forming a fluidized bed in the hearth, and the solid content and / or the sludge contained in the sludge forming the fluidized bed.
Or a process of supplying air from below the aggregate of the residue to flow the solid content and / or the aggregate of the residue, the method for treating industrial waste including sludge by a fluidized bed incinerator. I will provide a.

By using a solid content and / or a residue thereof contained in sludge instead of conventional silica sand as a material constituting the fluidized bed, a waste liquid containing an alkaline component such as Na or K may be treated. In addition, it does not combine with silica sand and adhere to the furnace wall, and continuous removal from the furnace bottom becomes impossible. The solids content of relatively light sludge and / or
Alternatively, the residue flows well by air from below. Thereby, the aggregate of the solid content and / or the residue contained in the sludge fluidized and deposited on the hearth forms a fluidized bed of a desired thickness.

The solid content and / or the residue contained in the sludge is lighter than silica sand, and the air flow from below is small. Further, the solid content contained in the sludge has a flammable component, so that less heat compensation is required as compared with silica sand.

According to a second aspect of the present invention, in the method for treating industrial waste according to the first aspect, the waste liquid is further injected into the fluidized bed from a waste liquid injection nozzle provided at a lower portion of the furnace body. A step of promoting fluidization of the aggregate of the minute and / or the residue thereof.

[0014] Drying and thermal decomposition of the waste liquid are promoted, and the fluidized bed on the hearth is actively fluidized to promote the combustion of solids contained in the sludge.

[0015] The third aspect of the present invention is the first or second aspect.
The method for treating industrial waste described in (1), further comprising a step of supplying waste plastic from a furnace top and burning it in a furnace body to compensate for heat.

Since waste plastic, which is industrial waste, is introduced into the furnace body from the furnace top, it is pyrolyzed and burned while descending in the high-temperature furnace body, and is used as a heat source.

According to a fourth aspect of the present invention, in the method for treating industrial waste according to any one of the first to third aspects,
The sludge supply step is a step of supplying waste liquid and sludge together from the furnace top into the furnace main body by high-pressure air.

The finely divided waste plastic generated in the pretreatment of the waste plastic is prevented from being scattered by being mixed into the sludge, and is effectively used as a heat source. If the fine waste plastic directly enters the furnace, there is a risk of burning and explosion. By mixing this into sludge, scattering is prevented, and burning and explosion are completely prevented.

According to a fifth aspect of the present invention, in the method for treating industrial waste according to any one of the first to fourth aspects,
Further, the method is characterized in that a step of measuring a temperature in the furnace main body and controlling a supply amount of the waste plastic and / or the liquid fuel in accordance with the combustion temperature is provided.

By controlling the combustion in the furnace body, the components and the flow rate of the exhaust gas toward the exhaust gas treatment facility are controlled.

According to a sixth aspect of the present invention, in the method for treating industrial waste according to any one of the first to fifth aspects,
Further, the method is characterized in that a step is provided in which solids contained in the sludge are completely burned and residues remaining after the solids are continuously burned out from the furnace bottom to keep the height of the fluidized bed almost constant.

The residue remaining after the solid matter contained in the sludge is completely burned is taken in from the furnace bottom even if Na and K in the molten state are taken in and the adhesion to the furnace wall is lost. Can be extracted. Continuous extraction of the residue enables continuous operation of the furnace.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for treating industrial waste containing sludge by a fluidized bed incinerator according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of a fluidized bed incinerator 1 that can be used to carry out the industrial waste treatment method of the present invention. In the illustrated preferred embodiment, the fluidized bed incinerator 1 has a furnace body 10 having a substantially circular cylindrical cross section. Furnace body 10
Has a height of about 10 from the furnace top 10a to the hearth 10b.
m, the diameter D1 of the hearth section 10b is 3 m, and the height H1 is 0.3 mm.
6m. The diameter D2 of the lower part 10c of the furnace body 10 is 4 m
And the height H2 from the hearth 10b to the upper end of the lower part 10c.
Is 4 m. The diameter D3 of the upper part 10d of the furnace body 10 is 6.5 m, and the height H3 from the furnace top 10a to the lower end of the upper part 10d is 6 m.

A large number of air holes 10e are formed in the hearth 10b, and fluidized air is introduced into the furnace body 10 through the air holes 10e. The diameter of the air hole 10e is 6
It is preferable that they are formed at a distance of 100 to 150 mm from each other. In this embodiment, the amount of fluidizing air supplied into the furnace main body 10 through the air holes 10e is 110
In Nm ³ / min, that of the case of using silica sand as a fluidized bed since it is 150 Nm ³ / min, can be reduced fluidizing air volume per minute 40 Nm ³ / min. This is because, as described later, lighter solids and / or residues thereof are deposited above the hearth 10b than the silica sand contained in the sludge. Alkaline components such as Na and K are discharged from the furnace as fly ash together with the steam gas and collected by an electric dust collector. Therefore, there is no problem such as corrosion of the bricks in the furnace due to alkali and generation of a molten material. The solid content and / or its residue contained in the relatively lightweight sludge flows better due to the air from below and the waste liquid from the waste liquid injection nozzle. Thereby, the aggregate of the solid content and / or the residue contained in the sludge fluidized and deposited on the hearth forms a fluidized bed of a desired thickness.

In the method of the present invention, since the object to be incinerated is selected, no large solid residue is generated in the hearth, and the fluidized bed is well stirred. The residue is finely divided by abrasion in the fluidized bed, is accompanied by the exhaust gas and becomes fly ash, and the entire amount is collected by an electric dust collector. Therefore, basically, it is not necessary to extract the residue from the fluidized bed, but it is also possible to extract a part of the residue in a batch. This makes it possible to eliminate the shutdown of the furnace for extracting the residue, or
There is an advantage that the number can be greatly reduced.

In the lower part 10c of the furnace main body 10, two to five burners 16 are installed at equal intervals in the circumferential direction as auxiliary combustion means. As fuel for the burner, in addition to heavy oil, recycled oil from waste oil or the like can be used. The on / off of the burner 16 is appropriately controlled while measuring the temperature of the combustion gas in the furnace main body 10 with a sensor (not shown) and the supply amount of another heat compensation source such as waste plastic. An injection nozzle 18 for injecting a waste liquid (waste acid or waste alkali) containing an alkali component such as Na or K into the furnace body 10 is provided at a lower portion 10c of the furnace body 10 at equal intervals in a circumferential direction. The book will be installed. The injection nozzle 18 is provided above the burner 16 so that the waste liquid injected therefrom is efficiently dried and burned by the fuel injected from the burner 16.

On the other hand, the furnace top 10a of the furnace body 10 has an inlet 20 for introducing waste plastic into the furnace body 10.
And an injection nozzle 22 for injecting waste liquid and sludge into the furnace main body 10.

As shown in FIG. 2, the waste plastic is preferably pre-treated before being supplied to the fluidized bed incinerator 1 as a heat compensation source. In the industrial waste treatment system shown in FIG. 2, waste plastic is collected in a waste plastic pit 2. This is pulverized into coarse particles of several mm to 50 mm by a waste plastic pulverizer, and is input into the furnace body 10 from the input port 20 using, for example, a screw conveyor. Those having a large particle size are supplied from a double damper (not shown) separately provided on the furnace top 10a.
You can also put it inside. Fine powder having a size of 1 mm or less is separated using, for example, a cyclone, a bag filter, or the like, and is mixed into the sludge via a path indicated by a dotted line in the figure. As a result, the fine waste plastic is directly transferred to the furnace body 1.
It can be prevented from over-burning, that is, exploding by being introduced into the air.

As shown in FIG. 1, the injection nozzle 22 has a triple tube structure made of SUS304. The same waste liquid as described above is supplied into the central inner pipe 22a, high-pressure air is supplied to the intermediate pipe 22b disposed outside the inner liquid, and further to the outer pipe 22c disposed outside the intermediate pipe 22b. Is supplied with sludge containing combustible solids such as activated sludge. In this embodiment, the outer diameter d1 of the outer tube 22c is about 125 mm, the tip of the nozzle is tapered, and the diameter d2 of the injection port at the tip of the nozzle is 80 mm. With this configuration, for example, when high-pressure air of 3 to 4 kg / cm ² is injected into the furnace main body 10 from the intermediate pipe 22b, 0 to 1 kg
The waste liquid supplied to the inner tube 22a at a pressure of / cm ² is also injected into the furnace body 10 in the same manner as the high-pressure air. As a result, the outlet of the injection nozzle 22 violently collides with the sludge supplied from the outer pipe 22c.

Therefore, the sludge injected into the furnace body 10 is dispersed in the furnace body 10. It is preferable that the sludge is uniformly dispersed in the furnace. For this reason, it is preferable that the injection nozzle 22 be inclined so as to face substantially the center of the upper space 10d of the furnace body 10. This inclination angle θ
Is about 13 ° in the illustrated embodiment, but good results could be obtained. The upper part 10d of the furnace main body 10 can be provided with a waste liquid inlet 24 capable of supplying only the waste liquid into the furnace, if necessary, separately from the injection nozzle 18.

In this embodiment, the furnace body 1
The waste plastics put into the chamber 0 are various plastics such as polyethylene and acrylic, but are pulverized to 1 to 50 mm so as to be easily burned in the furnace as described above. Therefore, in the present invention, the waste plastic charged into the furnace functions as a fuel for heat compensation. Similarly, the fine waste plastics mixed in the sludge also function as fuel when the water is removed and dried. Such fine powder waste plastic is mixed into the sludge and charged into the furnace main body 10, so that it is dried little by little with time, so that rapid combustion and explosion do not occur. Input port 2
The waste plastic from 0 is supplied by a screw conveyor (not shown), and the supply amount is appropriately adjusted according to the required combustion amount. The waste liquid is a scrubber cleaning liquid, a plating waste liquid, or the like generated in a factory, and contains an alkaline component such as Na or K. In addition, usually, COD (Chemical Oxy)
gen Demand) is 2,000 to 100,000 ppm. The sludge was activated sludge containing various organic substances such as sewage sludge.

Next, the operation of the fluidized bed incinerator 1 having the above configuration will be described. Fluidized air is supplied through the air hole 10e at a flow rate of 110 Nm ³ / min as described above.
Introduce into 0. When the burner 16 is ignited and the vicinity of the hearth 10b is heated, moisture in the sludge is removed, and the hearth 10b is heated.
Only solids deposit on top. This set of solids is levitated and fluidized by the fluidizing air passing through the air holes 10e and burns to form a fluidized bed of about 1.5 m. As the fuel used for the burner 16, a mixture of regenerated oil and waste oil can be used.

According to the present invention, the components constituting the fluidized bed are flammable solids and / or residues contained in the sludge, which are lighter in weight than conventional silica sand. This has the advantage that the amount of fluidizing air introduced into the furnace through the furnace can be reduced. Furthermore, there is an advantage that the heat energy required for raising the temperature to the predetermined temperature by the amount of the fluidized air is not required as compared with the conventional system.

As will be described later, the waste plastic introduced into the furnace from the furnace top 10a is thermally decomposed and burned, and further, unburned gas generated by hydrolysis of waste liquid, sludge, etc., is generated. By burning in the furnace, the furnace body 10
The inside is heated. Thus, the furnace body 1 including the fluidized bed
The lower part 10c of 0 is about 800 ° C., and the upper part 10d is 9 ° C.
The temperature is raised to a temperature of 00 to 1000 ° C.

According to the present invention, the sludge which is violently injected with high-pressure air from the injection nozzle 22 and is uniformly dispersed in the furnace is supplied from the waste liquid and injection port 20 which is also violently injected with high-pressure air from the injection nozzle 22. The waste plastic is completely dried in the upper part 10d of the furnace body 10 by the combustion of the waste plastic, and the solid content is further thermally decomposed in the lower part 10c.
As a result, the unburned gas is burned as a heat source in the upper portion 10d, and the unburned gas is discharged from an exhaust gas discharge port 26 formed in the furnace top 10a into an exhaust gas treatment facility, for example, a waste heat boiler 4 as shown in FIG. It is sent to a dust device 5, a wet type harmful gas removal device, and the like.

Further, the waste liquid injected from the waste liquid inlet 24 and the waste liquid injected from the injection nozzle 18 are also in the upper part 10d.
The moisture and the like are completely evaporated by the heating of the combustion gas in the above and the high temperature atmosphere in the lower part 10c, and the remaining solid content is thermally decomposed. The unburned gas generated by this is also burned in the furnace main body 10. Alkaline components such as Na and K in the waste liquid are discharged from the furnace as fly ash together with the steam gas and collected by an electric dust collector. Therefore, there is no problem such as corrosion of the bricks in the furnace due to alkali and generation of a melt. As described above, according to the method of the present invention, unlike the conventional apparatus, it does not bond with the silica sand and adheres to the furnace wall, so that it is not necessary to stop the operation of the furnace and perform the removing operation.

(Embodiment) A treatment system for carrying out the method for treating industrial waste according to the present invention shown in FIG. 2 comprises a waste liquid (waste acid and waste alkali) of 1550 tons / month and sludge (activated sludge).
It was possible to process 355 tons / month and 230 tons / month of waste plastic. In this case, the amount of the residue discharged from the furnace bottom was 30 tons / month, and a volume reduction rate of about 1.5% could be achieved.

The amount of fluidized air blown into the hearth 10b from the air hole 10e and the amount of high-pressure air blown from the intermediate pipe 22b of the spray nozzle 22 are 110 Nm ³ / min and 20 Nm.
^{At a} rate of ³ / min, the waste plastic to be introduced into the furnace from the inlet 20 is several mm to 50 mm, and waste plastic having a size smaller than that is mixed with sludge in advance and then injected into the furnace.
When the temperature in the furnace was measured, it was found to be 900-1000 ° C. in the upper 10d at 800 ° C. in the hearth 10b. The amount of exhaust gas discharged from the exhaust gas discharge port 26 is 180 to 200
At Nm3 / min, the amount of water vaporized and the amount of combustible exhaust gas such as waste plastics were larger than the amount of air supplied into the furnace. Carbon monoxide (CO) and oxygen (O
2) is 0.002-0.003% and 4-1 respectively
The air volume was adjusted to 3%. Carbon monoxide (CO)
Is more than 0.01%, oxygen is insufficient and residues increase.

[0039]

The method for treating industrial waste according to the present invention comprises:
Since silica sand is not used as the fluidized bed, even when a waste liquid containing an alkaline component such as Na or K is treated, it does not become bonded to the silica sand and adhere to the furnace wall, and continuous removal from the furnace bottom becomes impossible. Thereby, the treatment of industrial waste containing alkaline components such as Na and K can be continuously performed, and the operation efficiency of the furnace can be improved.

The solid content and / or its residue contained in the sludge constituting the fluidized bed is lighter than silica sand,
The air flow from below can be reduced, and the solid content contained in the sludge has a flammable component, so that it has the effect of requiring less heat compensation than silica sand.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a fluidized bed incinerator that can be used to carry out the industrial waste treatment method of the present invention.

FIG. 2 is a schematic diagram of an industrial waste treatment system including the fluidized bed incinerator of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fluidized bed incinerator 2 Waste plastic pit 3 Waste plastic crusher 4 Waste heat boiler 5 Electric dust collector 10 Furnace main body 10a Furnace top part 10b Furnace floor part 10c Lower part 10
d Upper part, 10e Air hole 16 Burner 18 Injection nozzle 20 Input port 22 Injection nozzle 22a Inner pipe, 22b Intermediate pipe, 22c Outer pipe 24 Waste liquid input port 26 Exhaust gas discharge port

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23G 7/00 102 F23G 7/00 102B 7/12 ZAB 7/12 ZABZ

Claims (6)

[Claims] 1. A method for treating industrial waste containing sludge by a fluidized bed incinerator having a fluidized bed in a furnace bed, comprising: supplying sludge into the furnace body from an upper part of the furnace body; A step of heating the inside of the furnace body with a burner provided at a lower part of the furnace body, a step of forming a fluidized bed in the furnace bed with the solid content and / or the residue thereof contained in the sludge, and Air is supplied from below the aggregate of the solid content and / or the residue contained in the sludge to be formed, and the solid content and / or
Or a step of flowing an aggregate of the residues, and a method for treating industrial waste containing sludge by a fluidized bed incinerator comprising: 2. The method for treating industrial waste according to claim 1, further comprising: injecting a waste liquid into said fluidized bed from a waste liquid injection nozzle provided at a lower portion of a furnace body to solid matter and / or a residue thereof. A method for treating industrial waste including sludge by a fluidized bed incinerator comprising a step of promoting fluidization of the aggregate of the above. 3. The method for treating industrial waste according to claim 1, further comprising a step of supplying waste plastic from a furnace top and burning it in a furnace body to compensate for heat. A method for treating industrial waste including sludge by a fluidized bed incinerator. 4. The method for treating industrial waste according to claim 1, wherein in the sludge supply step, the waste liquid and the sludge are supplied together from the furnace top into the furnace body by high-pressure air. A method for treating industrial waste containing sludge by a fluidized bed incinerator, wherein 5. The method for treating industrial waste according to claim 1, further comprising measuring a temperature inside the furnace main body, and supplying the amount of waste plastic and / or liquid fuel according to the combustion temperature. A method for treating industrial waste containing sludge by a fluidized bed incinerator, characterized by comprising a step of controlling wastewater. 6. The method for treating industrial waste according to any one of claims 1 to 5, further comprising the step of continuously burning solids contained in the sludge and remaining residues from the furnace bottom. A method for treating industrial waste containing sludge by a fluidized bed incinerator, comprising a step of maintaining the height of the fluidized bed at a substantially constant level.