JPH1114033A - Adsorption method of dioxide in exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adsorption method of dioxin in an exhaust gas which enables efficiently and safely to remove a poisonous substance in a combustion gas of waste or the like. SOLUTION: A pyrolytic carbon (m) separated by a separator 12 is blended with slaked lime (q) by a mixing tank 30 to be supplied into a combustion exhaust gas G2 flowing through an exhaust gas line L6 as adsorbent (k) of dioxin. The amount of the exhaust gas flowing through the line L6 is detected by a flow rate detector 21, a detection signal V1 obtained is inputted into a controller 22 to generate a control signal V2 , and the travel of a valve 23 provided in a line L10 can be controlled by the control signal V2 . The adsorbent (k) is supplied to a hopper (not illustrated) for storing the adsorbent (k). For example, activated charcoal and the slaked lime may be mixed. The adsorbent having the dioxin adsorbed thereby in the exhaust gas in the line L6 is trapped by a dust collector 18 together with flying ash (ash) and burned and melted by a melting furnace 6, and the dioxins adsorbed are also thermally decomposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adsorbing dioxin in exhaust gas, and more particularly to waste (general waste such as municipal waste from homes and offices, waste plastic, car shredder dust, waste office). machine,
The present invention relates to a method for adsorbing dioxin in exhaust gas, which is suitable for treating dioxin generated by combustion of combustible substances such as industrial waste such as electronic equipment and chemical products.

[0002]

2. Description of the Related Art It is well known that when combustible substances such as wastes are burned, dioxins, which are harmful substances, are generated in combustion gas. As a waste treatment device that suppresses the generation of dioxins, Japanese Patent Publication No. 6-5
There is an example described in 6253 gazette. In this example, waste containing combustibles, such as general waste such as municipal solid waste and industrial waste such as waste plastic, is placed in a pyrolysis reactor and heated in a low oxygen atmosphere. A gas and a pyrolysis residue mainly composed of nonvolatile components are generated.

[0003] Further, after the pyrolysis residue is cooled, it is guided to a separating device, where the combustible component of fine particles containing ash and coarse particles such as rubble such as metal, pottery, gravel, concrete pieces and the like. Separated into non-combustible components, pulverized the combustible components and led to a combustion melting furnace together with the pyrolysis gas, and combusted the combustible components in the combustion melting furnace,
The ash contained in the combustible component is converted into molten slag, and the molten slag is discharged, cooled and solidified.

[0004] Further, a dust collector for supplying waste gas from the combustion melting furnace to a waste heat steam generator to recover waste heat and removing dust (dust) in the heat recovered waste gas, and further, A gas purifier for desalting and desulfurizing the flue gas filtered by the dust collector is provided, and the flue gas is discharged into the atmosphere as a clean gas.

[0005]

Generally, dioxins are contained in combustion gas such as waste. The waste disposal apparatus described in the above publication in which the generation of dioxins is suppressed can be reused because the metal contained in the waste is recovered in an unoxidized state, and the molten combustion ash is recovered as slag In addition to being reused for this purpose, it has been noted that this type of waste treatment device can be operated with low NOx and has extremely small amount of harmful gases such as heavy metals. Are gathering.
Even in such a treatment system, dioxins may be generated in the combustion exhaust gas, albeit slightly. An object of the present invention is to provide a method for adsorbing dioxin in exhaust gas, which can efficiently and safely remove harmful substances contained in combustion gas such as waste.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above problems as follows. According to the first aspect of the present invention, dioxin generated by combustion of combustible materials such as waste is adsorbed on an adsorbent obtained by blending pyrolytic carbon generated by pyrolysis of waste and slaked lime, and this is burned. Dioxin is decomposed by burning in a melting furnace. According to the above configuration, dioxin is decomposed in the combustion melting furnace, and oxidation is prevented by blending slaked lime with pyrolytic carbon, so that safe and effective use of pyrolytic carbon can be achieved. In addition, the invention according to claim 2 adsorbs dioxin generated by the combustion of combustible substances such as waste to an adsorbent blended with activated carbon and slaked lime, and decomposes the dioxin by burning it in a combustion melting furnace. It is characterized by the following. Therefore, similarly to the above, dioxin is decomposed, oxidation is prevented by slaked lime, and safe and effective use of activated carbon can be achieved. A third aspect of the present invention provides a pyrolysis reactor that pyrolyzes waste to generate a pyrolysis gas and a pyrolysis residue mainly composed of a non-volatile component; A combustion and melting furnace that supplies and burns the pyrolysis gas and the combustible component after separating into a non-combustible component, and discharges molten slag and exhaust gas, and collects dust in the exhaust gas. In a waste treatment apparatus provided with a device, a means for adsorbing dioxin in the exhaust gas by the adsorption method according to claim 1 or 2 is provided at a stage preceding the dust collecting device. is there. According to such a configuration, dioxin in exhaust gas is adsorbed to an adsorbent obtained by blending slaked lime with pyrolytic carbon or activated carbon, collected by a dust collector, and supplied to a combustion melting furnace,
Dioxin can be decomposed in a combustion melting furnace.

[0007]

Embodiments of the present invention will be described below. The embodiment of the present invention utilizes pyrolytic carbon or activated carbon as an adsorbent, blends slaked lime to prevent oxidation, adsorbs dioxin contained in general combustion gas, and adsorbs this dioxin adsorbent. It burns and melts in a combustion melting furnace to decompose dioxin.

Referring to FIG. 1, an embodiment in which dioxin is removed by effectively utilizing pyrolytic carbon in a waste treatment system will be described as an example of the present embodiment. In FIG. 1, a waste supply device 1 includes a crane 3 having a bucket 2 and a screw feeder 4, and supplies waste a crushed to a predetermined size by a crusher (not shown) to a pyrolysis reactor 5. Is done. The thermal decomposition reactor 5 is constituted by a horizontal rotary drum, heating the air b which has been heated by air heater 7 disposed on the downstream side of the melting furnace 6 is incinerator is supplied from the line L _1, 30 in the furnace
The heat treatment is performed at a temperature of 0 ° C to 600 ° C, usually 450 ° C. The inside of the pyrolysis reactor 5 is maintained in a low oxygen atmosphere at a pressure lower than the atmospheric pressure by a sealing mechanism (not shown) and an induction blower 8 provided at a subsequent stage of the series of devices. And pyrolyzed to generate a carbonized gas G ₁ and a pyrolysis residue c.

The dry distillation gas G ₁ and the pyrolysis residue c are:
Separated by the discharge device 9 connected to the pyrolysis reactor 5, the carbonized gas G ₁ is supplied to the burner 10 of the melting furnace 6 via the line L ₂ . On the other hand, the pyrolysis residue c is cooled by the cooling device 11 to, for example, 80 ° C.
To separate into a combustible component d, a non-metal component e which is a non-combustible component, and a non-metal component f such as rubble. This metal component e
Is collected in the container 13, and the nonmetallic component f is separately crushed and supplied to the melting furnace 6 to be made into a molten slag h.

The combustible component d separated by the separation device 12 is pulverized by a crusher 14 into fine powder having a size of, for example, 1 mm or less. The pulverized combustible component d ′ is supplied from the line L ₃ to the melting furnace 6. In addition to being supplied to the burner 10, in the present embodiment, the combustible component d is mainly composed of pyrolytic carbon m and ash.
Was mixed and used as an adsorbent k for dioxins.

[0011] That is, the pyrolytic carbon m separated by the separator device 12, after crushing in subsequent crusher 14, the some or all, blending slaked lime in the mixing tank 30, the dust collecting line L ₁₀ It is connected to an exhaust gas line L ₆ connected to the device 18, and is directly supplied as a dioxin adsorbent k to the combustion exhaust gas G ₂ flowing through this line L ₆ .

[0012] In this case, the exhaust amount of the exhaust gas G ₂ flowing through the gas line L ₆ is detected by the flow detector 21, to create a resultant detection signal V ₁ input to the control signal V ₂ to the control device 22,
By this control signal V ₂ , the valve 23 provided on the line L ₁₀
The opening degree is controlled. Further, the adsorbent k supplied to the adsorbent storage hopper (not示図), where, for example, activated carbon and hydrated lime are mixed, then can be supplied to the exhaust gas line L _6. Since the exhaust gas line L ₆ negative pressure, dioxin adsorbent k can be easily supplied into the combustion gas G _2.

On the other hand, the combustible component d 'is converted to about 1,300 in the melting furnace 6 by the dry distillation gas G ₁ supplied from the line L ₂ and the combustion air g supplied from the line L ₄ by the forced blower 15. Most of the ash contained in the combustible component d ′ and the combustion ash which are burned in a high temperature range of ° C. flow down as molten slag h, and are cooled and solidified in the water tank 16. The solidified slag is effectively used as a building material such as a pavement material.

The combustion gas G ₂ generated in the melting furnace 6 passes through a line L _{5 and} passes through an air heater 7 and a subsequent waste heat boiler 17.
By the heat recovery reaches the exhaust gas line L ₆ of the upstream side of the dust collecting device 18 (first exhaust gas treatment unit), where, as described above, dioxin in the exhaust gas is adsorbed by the adsorbent k.

The adsorbent having adsorbed dioxins in this manner is collected in the dust collecting device 18 together with fly ash (ash) accompanying the combustion gas G ₂ . And this dust collector 18
Sorbent trapped in and ash, burning or melted is supplied to the melting furnace 6 via line L _7, dioxins adsorbed on the adsorbent is also thermally decomposed.

On the other hand, the combustion gas G ₃ from which the ash and the adsorbent have been collected by the dust collecting device 18 is guided to a gas cleaning device (second exhaust gas treatment means) 24 via a line ₈ , where the gas is cleaned. Te is desalted, most become clean exhaust gas G ₄ are released from the chimney 25 into the atmosphere, some of which is supplied to the cooling device 11 as an inert gas via line L _9. The steam s obtained by heat recovery in the waste heat boiler 17 is recovered as electricity by a power generator 26 including a steam turbine and a power generator.

As described above, according to these embodiments, the pyrolytic carbon generated in the waste treatment system is effectively used, and the oxidation is suppressed by blending slaked lime to reduce the dioxin in the exhaust gas. It is adsorbed and returned to the combustion melting furnace to burn and melt to decompose dioxin. Slaked lime may be blended with activated carbon instead of pyrolytic carbon, or slaked lime may be blended with pyrolytic carbon and activated carbon. Also, slaked lime can be blended with pyrolytic carbon generated in the pyrolysis reactor to form an adsorbent, which can be used for dioxin removal from exhaust gas of other combustion systems.

[0018]

As is apparent from the above description, according to the present invention, dioxin contained in combustion gas such as waste can be efficiently and safely removed.

[Brief description of the drawings]

FIG. 1 is a system diagram of a waste treatment apparatus to which a dioxin adsorption method of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Waste supply apparatus 2 Bucket 3 Crane 4 Screw feeder 5 Pyrolysis reactor 6 Melting furnace 7 Air heater 8 Induction blower 9 Discharge device 10 Burner 11 Cooling device 12 Separation device 13 Container 14 Crusher 15 Push-in blower 16 Water tank 17 Waste Heat boiler 18 Dust collector 19 Hopper 20 Activated carbon supply pipe 21 Flow rate detector 22 Control device 23 Valve 24 Cleaning device 25 Chimney 26 Power generation device 30 Mixing tank

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23G 5/16 ZAB F23J 1/00 B F23J 1/00 B01D 53/34 134E

Claims (3)

[Claims] An adsorbent obtained by blending pyrolytic carbon generated by thermal decomposition of waste and slaked lime adsorbs dioxin generated by combustion of a combustible substance such as waste, and the resulting adsorbent is used in a combustion melting furnace. A method for adsorbing dioxin in exhaust gas, characterized in that dioxin is decomposed by burning in a furnace. 2. An adsorbent blended with activated carbon and slaked lime adsorbs dioxin generated by the combustion of combustibles such as waste, and burns it in a combustion melting furnace to decompose dioxin. Of dioxin in exhaust gas. 3. A pyrolysis reactor which pyrolyzes waste to produce a pyrolysis gas and a pyrolysis residue mainly composed of a non-volatile component, and converts the pyrolysis residue into a combustible component and a non-combustible component. And a combustion-melting furnace for supplying and burning the pyrolysis gas and the combustible component, discharging molten slag and exhaust gas, and a dust-collecting device for discharging dust in the exhaust gas. 3. A waste treatment apparatus comprising: a means for adsorbing dioxin in the exhaust gas by the adsorption method according to claim 1 or 2 in a preceding stage of the dust collection apparatus.