JP2002205044A - Waste treatment plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste treatment plant which can dispense with the final disposal site of waste and can protect the environment. SOLUTION: This waste treatment plant is provided with a thermal decomposing drum 12 for decomposing waste thermally to generate gas and a residue, a firing/melting furnace 13 for receiving the gas generated in the drum 12 and a carbon residue sorted from the residue generated in the drum 12 and burning the received gas and residue, an exhaust gas scrubbing unit 22 of a wet type for removing HCl and SOX form an exhaust gas, a dehydrated sludge producing means 27 for producing dehydrated sludge by flocculating/settling heavy metal- containing dust discharged from the unit 22 and a dehydrated sludge supplying means 30 for supplying the dehydrated sludge to at least one of the drum 12 and the furnace 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention provides a pyrolysis drum for pyrolyzing waste into a pyrolysis gas and a pyrolysis residue, and separates the pyrolysis gas from the carbon residue selected from the pyrolysis residue. A combustion melting furnace for receiving and burning is provided, and an exhaust gas cleaning device for removing HCl (hydrogen chloride) and SO _x (sulfur oxide) from exhaust gas is provided. Dust containing heavy metals from the exhaust gas cleaning device is coagulated and settled to be dehydrated. The present invention relates to a waste treatment plant provided with dewatering sludge converting means for converting sludge.

[0002]

2. Description of the Related Art There are two types of exhaust gas cleaning devices in the above-mentioned waste treatment plants: dry exhaust gas cleaning devices and wet exhaust gas cleaning devices.

Of these, in a wet exhaust gas cleaning apparatus, caustic soda (NaOH) is used as a reactant, and as a residue, water-soluble NaCl as a reaction product and a small amount of dust (heavy metals (Pb, Cd, Hg, Cr, etc.)) are removed. Including).

Conventionally, in the above-mentioned waste treatment plant, means for treating dust containing heavy metals from a wet exhaust gas cleaning device include chemical (chelate) treatment means for preventing elution of heavy metals, and aggregation of the dust. -Only a means for dehydrating sludge to settle into dewatered sludge was provided.

[0005]

According to the above-mentioned conventional construction, as means for treating dust containing heavy metals from an exhaust gas cleaning apparatus, there are chemical treatment means for preventing elution of heavy metals, and aggregation of dust containing heavy metals.・ Because only dewatering sludge conversion means to settle and make dewatered sludge was provided,
Dewatered sludge must be landfilled at the final disposal site, which requires a lot of time and labor to secure the final disposal site, and it is not desirable in terms of environmental conservation, leaving room for improvement. It had been.

An object of the present invention is to provide a waste treatment plant which can eliminate the need for a final disposal site for waste and protect the environment.

[0007]

The constitution, operation and effect of the invention according to claim 1 are as follows.

In the waste treatment plant described at the beginning, the exhaust gas cleaning device is configured as a wet exhaust gas cleaning device, and the dewatered sludge is supplied to at least one of the pyrolysis drum and a combustion melting furnace. Dewatered sludge supply means is provided.

[Operation] Dust containing heavy metals from a wet exhaust gas cleaning apparatus is coagulated and precipitated by dewatering sludge forming means to make dewatered sludge.

Then, the dewatered sludge is supplied to at least one of the pyrolysis drum and the combustion melting furnace by the dewatered sludge supply means.

In this type of waste treatment plant, carbon residues and dust dust are blown into a combustion melting furnace, which burns and melts, and slag is discharged from the furnace bottom.

As described above, when the dewatered sludge is supplied to at least one of the pyrolysis drum and the combustion melting furnace, heavy metals in the dewatered sludge are sealed in the slag in the combustion melting furnace and discharged from the furnace bottom. You.

Since the slag is generally used as a road pavement material, according to the first aspect of the present invention, no heavy metal is emitted as waste.

[Effect] Therefore, there is no need to bury dewatered sludge in a final disposal site, and a final disposal site for waste can be made unnecessary, thereby providing a waste treatment plant capable of protecting the environment. Was completed.

The structure, operation and effect of the invention according to claim 2 are as follows.

[Structure] In the structure according to the first aspect of the present invention, a salt recovery apparatus is provided for recovering water-soluble NaCl from the dewatering sludge forming means from water.

[Action] In addition to providing the same action as the action according to the first aspect, the water-soluble NaCl (sodium chloride) from the dewatering sludge forming means is recovered from the water by the salt recovery apparatus. NaCl can be reused as industrial salt.

[Effects] Therefore, in addition to the same effects as the effects of the configuration of the first aspect, it is possible to provide a waste treatment plant that does not generate waste and can further protect the environment. Was.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a pyrolysis gasification and melting plant as a waste treatment plant. This pyrolysis gasification and melting plant includes a pretreatment facility 1, a pyrolysis reaction facility 2, a pyrolysis residue sorting facility 3, a high-temperature combustion and melting facility 4, a boiler power generation facility 5, and an exhaust gas treatment facility 6.

[Pretreatment facility 1] The waste stored in the waste pit 7 is crushed by a crusher 8 to 150 mm square or less, and the crushed waste is sent to the pyrolysis drum facility 2 by a transport device 9.

[Thermal Decomposition Drum Facility 2] The waste from the waste pit 7 is received into the thermal decomposition drum 12 via the screw conveyor 10, and the waste is heated to about 450 ° C. in an oxygen-free or low-oxygen atmosphere. Decomposes into cracked gas and pyrolysis residue.

The pyrolysis gas is sent to a high-temperature combustion melting furnace 13,
The pyrolysis residue is sent to the pyrolysis residue sorting equipment 3.

[Thermal Decomposition Residue Sorting Facility 3] The pyrolysis residue from the pyrolysis reaction facility 2 is conveyed while being cooled by a cooling conveyor 14, and is passed through a screen 15 and a sorter 16 (a magnetic sorter or an aluminum sorter). Valuables such as iron, aluminum, copper, and glass are sorted and collected, and carbon residues other than the valuables are sent to the high-temperature combustion melting furnace 13.

[High-temperature combustion / melting equipment 4] Pyrolysis gas, carbon residue, dust collection dust (dust from boiler and dust collector)
Is blown into the high-temperature combustion melting furnace 13 from the furnace top side, and these are swirled and burned. The incinerated ash and dust particles are melted and continuously discharged from the furnace bottom.

Since the waste is converted into fuel in the pyrolysis drum facility 2, it can be burned at a low air ratio, and the combustion at a low air ratio reduces the amount of exhaust gas. Multi-stage combustion and recirculation of exhaust gas to reduce NOx, and sufficient residence time to reduce dioxin.

[Boiler power generation equipment 5] Exhaust gas is cooled in a boiler radiation zone and brought to a uniform temperature in an evaporating tube group.
It is sent to the superheated steam tube group at 00 ° C and sent to the dust collector 17 at about 200 ° C through an economizer. 40 at boiler 18
ata ・ 400 ° C steam and heat recovery
The electricity is collected by the generator 20.

[Exhaust gas treatment equipment 6] Temperature reducing tower 21, dust collector 17, wet exhaust gas cleaning device 22, activated coke tower 23
It comprises a denitration device 24, a chimney 25, etc.

The exhaust gas cleaning device 22 removes HC from exhaust gas.
1 and SO _X are removed by using caustic soda as a reactant, and as a residue, a reaction product, water-soluble Na
Cl and a small amount of dust (heavy metals (Pb, Cd, Hg, Cr
Etc.) are discharged.

[0030] The activated coke tower 23 removes dioxin, NOx removal apparatus 24 for removing NO _X.

An exhaust gas residue treatment section 31 for treating the residue from the exhaust gas cleaning device 22 is provided. Next, the exhaust gas residue processing section 31 will be described.

As shown in FIGS. 1 and 2, the exhaust gas residue treatment section 31 is a chemical treatment means for preventing heavy metals (Pb, Cd, Hg, Cr, etc.) from being eluted from the residue from the exhaust gas cleaning device 22. 26, a dewatering sludge means 27 for coagulating and sedimenting the dust containing heavy metals from the chemical treatment means 26 into dewatered sludge, and a mercury treatment means 28 from the dewatering sludge means 27 for mercury-treating the aqueous solution of NaCl in water And a salt water evaporator 29 (corresponding to a salt recovery device) for recovering NaCl from the aqueous solution from the mercury treatment means 28, and a dewatered sludge supply means 30 for supplying dewatered sludge to the pyrolysis drum 12. is there.

In FIG. 1BF is an abbreviation for a first bag filter which is an example of a dust collector. As is well known, a scrubber is an example of an exhaust gas cleaning device.

With the above structure, the residue from the wet exhaust gas cleaning device 22 is treated with the chemical treatment by the chemical treatment means 26 to prevent heavy metals from being eluted from the residue. In the residue from the exhaust gas cleaning device 22, 5% of heavy metal remains, and 99% of chlorine remains.

Next, the dust containing the heavy metal from the chemical treatment means 26 is aggregated and settled by the dewatering sludge forming means 27 to make dewatered sludge.

Then, the dewatered sludge is supplied to the dewatered sludge supply means 30.
To the thermal decomposition drum 12. Also, the salt water evaporator 29
To recover NaCl from the aqueous solution from the mercury treatment means 28. From the chimney 25, 1% of chlorine is discharged.

In this waste treatment plant, pyrolysis gas, carbon residue, and dust dust are blown into the high-temperature combustion melting furnace 13 from the furnace top and swirled to burn and melt the incinerated ash and dust dust. The slag is discharged from the furnace bottom. When the dewatered sludge is supplied to the pyrolysis drum 12 as described above, heavy metals in the dewatered sludge are contained in the slag in the high-temperature combustion melting furnace 13 and discharged from the furnace bottom. You.

Thus, the slag discharged from the furnace bottom contains all of the heavy metals (100% of heavy metals). Contains no chlorine (0%).

Since the slag is used as a road pavement material, according to the above structure, no heavy metal is emitted as waste.

Further, the mercury treatment means 2 is provided by the salt water evaporator 29.
NaCl is recovered from the aqueous solution from
Can be reused as an industrial salt.

As a result, no waste is generated, and a final disposal site for the waste can be eliminated, thereby protecting the environment.

[Another Embodiment] The dewatered sludge supply means 30
May be configured to supply the dewatered sludge to the high-temperature combustion melting furnace 13.

Further, the dewatered sludge may be supplied to both the thermal decomposition drum 12 and the high-temperature combustion melting furnace 13.

A spray evaporator may be provided instead of the salt water evaporator 29, and these are collectively referred to as a salt recovery device.

The present invention can be applied to a waste treatment plant not provided with the salt recovery device.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a pyrolysis gasification and melting plant.

FIG. 2 is a diagram showing an exhaust gas residue processing unit and the like.

[Description of Signs] 12 Pyrolysis drum 13 Combustion / melting furnace 22 Exhaust gas cleaning device 26 Chemical treatment device 27 Dehydration sludge conversion device 29 Salt recovery device 30 Dehydration sludge supply device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 11/00 F23G 5/16 ZABE 4D059 F23G 5/00 ZAB 7/00 ZAB 115 102B 5/027 ZAB B01D 53 / 34 125C 5/16 ZAB 134B 7/00 ZAB 136Z 102 F23J 15/00 C F23J 15/02 F term (reference) 3K061 AA07 AA16 AB02 AC02 BA05 3K070 DA03 DA05 DA21 DA23 3K078 AA05 AA06 BA26 CA02 4A002 AA02 AA02AA02A19A BA14 BA20 CA01 CA13 DA02 DA12 DA35 EA02 EA05 FA04 4D004 AA01 AA36 AB07 AC05 BA02 BA03 CA04 CA09 CA24 CA26 CA27 CA28 CA32 CA40 CB04 CB13 CB34 CB42 CB43 CB45 CC03 CC12 4D059 AA11 BB03 BB04 CB01 CC04

Claims (2)

[Claims] 1. A pyrolysis drum for pyrolyzing waste into a pyrolysis gas and a pyrolysis residue and receiving and burning the pyrolysis gas and a carbon residue selected from the pyrolysis residue. Furnace is installed, and HC is
a waste gas treatment plant provided with a flue gas cleaning device for removing l and SO _X , and provided with a dewatering sludge forming means for coagulating and sedimenting dust containing heavy metals from the flue gas cleaning device into dewatered sludge. A waste treatment plant comprising a cleaning device configured as a wet exhaust gas cleaning device and a dewatered sludge supply means for supplying the dewatered sludge to at least one of the pyrolysis drum and a combustion melting furnace. 2. The water-soluble Na from the dewatering sludge forming means.
2. A salt recovery device for recovering Cl from water is provided.
Waste treatment plant as described.