JP3827816B2 - Method for recovering active ingredient from desalting residue and waste treatment apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for recovering active ingredients from desalted residues, and in particular, waste (general waste such as municipal waste from homes and offices, waste plastic, car shredder / dust, waste office equipment, electronic equipment) The present invention relates to a method for recovering an active ingredient from a desalted residue, which is suitable for treating a desalted residue of exhaust gas generated by pyrolyzing industrial waste such as chemical products and the like.
[0002]
[Prior art]
As one of the processing equipment for waste containing combustible materials such as municipal waste and other industrial waste such as waste plastic, waste is put in a pyrolysis reactor and heated in a low oxygen atmosphere, Pyrolysis produces a pyrolysis gas and a pyrolysis residue mainly composed of non-volatile components. Further, after cooling the pyrolysis residue, the pyrolysis residue is led to a separation device, and the flammability of fine particles containing ash in the separation device The components are separated into coarse incombustible components such as rubble such as metal, ceramics, gravel, and concrete pieces, and combustible components are pulverized. The slag contained in the combustible component is made into molten slag, and the molten slag is discharged and cooled and solidified. , Waste gas from the combustion melting furnace Waste was to be supplied to the waste heat steam generator for recovering waste heat processing apparatus is known (e.g., see Japanese Patent Kokoku 6-56253).
[0003]
As disclosed in the above publication, the exhaust gas from the combustion melting furnace used in this kind of waste treatment apparatus is recovered by the waste heat steam generator and then the first exhaust gas treatment means (dust collector). ) To remove dust (soot dust), and the second exhaust gas treatment means (gas purification device) removes the reaction product as a desalted residue by desalting and desulfurization treatment, and the atmosphere as clean flue gas Released into.
[0004]
[Problems to be solved by the invention]
However, in the above prior art, although the desalination residue discharged from the gas purification device is small, it contains heavy metals (PbO, PbCl ₂ etc.) removed from the exhaust gas and a small amount of dioxin, so it solidifies with a large amount of cement. It was usually landfilled or discarded. Moreover, in the usual method, calcium chloride (Ca (OH) ₂ ) added for demineralization / desulfurization reacts with hydrogen chloride (HCl) in the exhaust gas to react with calcium chloride (CaCl ₂ ). Since this CaCl ₂ is highly hygroscopic, there is a problem that it is difficult to handle in a dry process. In addition, the method of washing exhaust gas with a wet process and discharging wastewater containing impurities with chemical treatment has environmental problems and the range of discharge is limited.
[0005]
The object of the present invention is to make effective use of the desalting residue discharged by the dry treatment of exhaust gas, and to dispose of the desalting residue in the waste treatment system, rather than unnecessarily disposing of it outside the system. It is to provide a method for recovering an active ingredient from
[0006]
[Means for Solving the Problems]
The above problems are solved as follows. First, exhaust gas generated by combustion of combustibles such as waste is desalted and desulfurized by a dry process to discharge the desalted residue, and after adding water to the desalted residue, the mixture is mixed. The active ingredient is recovered by evaporation to dryness . Thereby , the active ingredient contained in a desalting residue can be collect | recovered easily, and the large amount of cement conventionally used in order to harden a desalting residue can be abbreviate | omitted. Here, according to claim 1 invention, the combustion of combustible materials such as wastes, the exhaust gas from the combustion melting furnace for discharging the molten slag, to remove the dust by the first exhaust gas treatment means, then dust After adding the desalination desulfurization agent to the removed exhaust gas, the desalination residue is discharged by the second exhaust gas treatment means that performs desalination / desulfurization treatment in a dry manner, and water is added to the desalination residue and mixed . In addition to removing heavy metals contained in the desalting residue, the filtered water is evaporated to dryness to recover the active ingredient. Therefore, there is a slightly desalination residue may be contained, but heavy metals removed from the exhaust gas (PbO, PbCl _2, etc.), fixed with agents harmless, or reduced to Yamamoto and cake together with residue, Can be landfilled. Furthermore, by evaporating the filtered water to dryness, an effective substance such as a salt that does not contain harmful substances can be recovered. The invention according to claim 2 is characterized in that cooling water for molten slag generated by burning and melting the combustible material is used as water added to the desalting residue. Therefore, since the water in the system of the waste combustion apparatus is reused without newly using a large amount of water, the cost is reduced. According to a third aspect of the present invention, there is provided a pyrolysis reactor that pyrolyzes waste to produce pyrolysis gas and a pyrolysis residue mainly composed of nonvolatile components, and the pyrolysis residue as a combustible component. after separating into a non combustible components, a combustion melting furnace for discharging molten slag and waste gas are supplied to the combustion of said pyrolysis gas and the combustible components, in the exhaust gas discharged from the combustion melting furnace A first exhaust gas treatment device for removing dust, a demineralization agent addition means for adding a demineralization agent to the exhaust gas discharged from the first exhaust gas treatment device, and the demineralization agent added in dry waste treatment apparatus comprising providing a second exhaust gas treatment device for discharging the exhaust gas desalting and desulfurization process to desalted residue, by the recovery method according to claim 1 or 2, wherein the de-Shiozan渣Desalination residue to recover active ingredients from In which it characterized in that a physical means. Therefore, the desalted residue is not simply discarded out of the system, but can be evaporated and dried by the desalted residue processing means to recover an active ingredient such as salt and reused as a snow melting agent or a moisture absorbent. Also, recycling within the waste treatment system becomes possible.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram for explaining an embodiment of the present invention. In the present embodiment, the desalting residue treatment means 30 treats the desalination residue 31 discharged from the gas purification device (second exhaust gas treatment means) 13 to recover the active components.
As shown in FIG. 1, a dust collector (first collector) is installed in a combustion melting furnace installed on the front side of the first exhaust gas flow path 10 or a waste heat boiler that recovers heat from the exhaust gas of the combustion melting furnace to generate steam. 1, the exhaust gas from which dust has been removed is demineralized and desulfurized by the gas purification device (second exhaust gas treatment means) 13 through the second exhaust gas flow path 12. . A supply path 17 for slaked lime 15 and auxiliary 16 added for demineralization / desulfurization is connected to the second exhaust gas flow path 12.
[0008]
In the gas purification device 13, the purified exhaust gas and the desalting residue 31 are generated. The desalting residue 31 is mixed by adding water 38 in the mixing tank 32. If heavy metal (PbO, PbCl ₂ or the like) is contained, the chemical is added to fix the heavy metal, and the dehydrator 33 performs dehydration filtration. The filtered water is evaporated to dryness with a dryer 35 and separated into a solid salt compound 36 and evaporated water 37. Thus, the salt compound 36 obtained by evaporating and drying the desalted residue is effectively reused as a snow melting agent, a hygroscopic agent and the like. The evaporated water 37 may be released to the atmosphere or reused in the system. Further, the detoxified cake 34 by dehydration may be reduced to the mountain or solidified for disposal in landfill. The exhaust gas purified by the gas purification device 13 is attracted by the induction blower 18, reheated by the white smoke preventer 19 with the preheated air for preventing white smoke, and discharged from the chimney 21 as clean flue gas. Is done.
[0009]
In the above example, dust is removed by the dust collector, and then hydrogen chloride and acidic gas in the exhaust gas are removed by the gas purification device, but slaked lime is collected in the front stage of the bag filter while collecting dust with the bag filter. The present invention is effective even when (Ca (OH) ₂ ) is added to remove acidic gas such as hydrogen chloride, dioxin or heavy metal. In any case, the desalted residue discharged has a very high salt concentration (almost CaCl ₂ ). Conventionally, since this desalted residue has high hygroscopicity and poor handling, it has been disposed of outside the system by solidifying with cement or the like.
The present inventors pay attention to the fact that the desalted residue has a high salt concentration and hygroscopicity, and devise a method for recovering the active ingredient by making a slurry using its properties rather than simply disposing it outside the system. did. As a result, the range of effective utilization of the desalting residue has been expanded and can be reused as a snow melting agent, a moisture absorbent and the like.
[0010]
Next, an embodiment of a waste treatment apparatus provided with a desalting residue treatment means according to the present invention will be described.
FIG. 2 is a system diagram of the waste treatment apparatus 50 according to the present invention. In the waste treatment apparatus 50, the crusher 52 is a biaxial shearing type crusher, for example, disposed in the receiving yard. Waste a such as municipal waste is supplied to the crusher 52 by the first conveyor 51. Here, for example, it is crushed to 150 mm square or less. The crushed waste a is introduced by the second conveyor 53 and supplied to the pyrolysis reactor 55 through the screw feeder 54. For example, a horizontal rotary drum is used for the thermal decomposition reactor 55, and the inside thereof is maintained in a low oxygen atmosphere by a seal mechanism (not shown), and heat exchange disposed on the downstream side of the combustion melting furnace 63 as a combustor. Heated air heated by the vessel 68 is supplied from the line L ₁ .
[0011]
The waste a supplied into the pyrolysis reactor 55 by the heated air is heated to 300 to 600 ° C., usually about 450 ° C. As a result, the waste a is thermally decomposed to generate a pyrolysis gas G ₁ and a mainly non-volatile pyrolysis residue b. The pyrolysis gas G ₁ and the pyrolysis residue b produced in the pyrolysis reactor 55 are separated by the discharge device 56, and the pyrolysis gas G ₁ passes through a line L ₂ that is a pyrolysis gas pipe. Then, it is supplied to the burner 62 of the combustion melting furnace 63.
[0012]
Pyrolysis residue b varies depending on the type of waste a, but in the case of municipal waste in Japan, according to the knowledge of the present inventors,
Most combustibles with relatively fine particles 10-60%
5-40% relatively fine ash
Coarse-grained metal component 7-50%
Coarse-grained rubble, pottery, concrete, etc. 10-60%
It turned out to be composed.
[0013]
Since the pyrolysis residue b having such components is discharged at a relatively high temperature of about 450 ° C., it is cooled to about 80 ° C. by the cooling device 57 and led to the separation device 58, where the combustible component c And incombustible component d. As the separation device 58, for example, a known separator of a magnetic separation type, a centrifugal type, or a wind sorting type is used. The combustible component c from which the non-combustible component d is separated and removed in this way is supplied to the pulverizer 60. The pulverizer 60 is suitably a roll type, a tube mill type, a rod mill type, a ball mill type or the like, and is appropriately selected depending on the properties of the waste to be treated.
[0014]
The combustible component c in this grinder 60 is preferably ground to all 1mm or less, the ground combustible component c is supplied to the burner 62 of the burning melting furnace 63 via line L _3. On the other hand, the combustion air and pyrolysis gas G ₁ and the combustible component c supplied from the line L ₄ by the blower 61 are combusted in a high temperature region of about 1300 ° C. in the combustion melting furnace 63, and the combustible component is generated by this combustion. Combustion ash generated from the relatively fine ash of c is melted to produce molten slag f.
[0015]
The non-combustible component d is stored in the container 59. Unburned waste e is fed towards the possible under the combustion melting furnace 63 through a line L _5. At this time, the non-combustible waste e is preferably made into fine particles of 1 mm or less and heated in order to improve combustion and melting efficiency. Therefore, the line L crusher provided ₅ crushing provided a pulverizer 64 and heater 65, it is being fed to the combustion melting furnace 63 is a processing such as grinding and heating. Therefore, heated air heated by the heat exchanger 68 disposed on the downstream side of the combustion melting furnace 63, and is supplied to the heater 65 via a line L _8.
[0016]
Further, the incombustible waste e is melted in the combustion melting furnace 63 to become slag g and mixed with the molten slag f by the combustion ash, falls from the slag discharge port 66 into the water tank 67 and is made into granulated slag. The The granulated slag is blocked into a predetermined shape by an apparatus (not shown) or formed into a granular shape, and can be reused as a building material or a paving material. In this case, the non-combustible waste e may be mixed into the molten slag f without melting as necessary.
[0017]
The combustion exhaust gas G ₂ generated in the combustion melting furnace 63 of such a waste treatment apparatus is heat recovered by the heat exchanger 68 and further recovered by the waste heat boiler 69 from the line L ₆ . removing the dust 72 by the exhaust gas treatment device 71, in addition to desalting desulfurizing agent 78, it is desalted and desulfurization in the second exhaust gas treatment unit 73, after discharging the Datsushiozan渣74, low-temperature clean exhaust gas G ₃ Then, the air is discharged from the chimney 76 to the atmosphere via the induction fan 75. Further, a part of the exhaust gas G ₃ is supplied to the cooling device 57 through the line L ₇ by the blower 77. Dust 72 collecting in the first exhaust gas treatment device 71 is returned by the line L ₉ to the combustion melting furnace 63, it is mixed melted and into the slag. Incidentally, steam generated in the waste heat boiler 69 is fed to the generator 70 to the steam turbine to work, also, part of it is sent to the heater 65 by the line L _6.
[0018]
In such a waste treatment apparatus, a desalination residue treatment means 80 for recovering an active ingredient from the desalination residue 74 discharged from the second exhaust gas treatment device 73 is provided. The desalting residue treatment means 80 is configured in the same manner as that shown in FIG. 1. In this example, the circulating water in the slag cooling water tank 67 is reused for the water 81 for slurrying the desalting residue 74. The detoxification cake 82 is taken out by the dehydration treatment in the desalting residue treatment means 80, and the filtered water is evaporated to dryness to recover the effective salt compound 83. Further, the evaporated water 84 is condensed here and recycled to the slag cooling water tank 67.
[0019]
The salt compound recovered in this way can be reused as a snow melting agent, a hygroscopic agent, etc., and can be used effectively industrially. In this example, harmful substances such as heavy metals and dioxins are processed by the exhaust gas treatment up to the second exhaust gas treatment device, and the amount contained in the desalting residue is small. Therefore, it is possible to reduce the drug for fixing heavy metals. In addition, although the cost is reduced by circulating the water added to the desalted residue and the evaporated water generated by evaporation to dryness with the slag cooling water tank, it helps to complete the recycling in the waste treatment system. The invention is not limited to this. Of course, the present invention can be applied not only to exhaust gas from a combustion melting furnace but also to exhaust gas generated by combustion of combustible materials such as waste.
[0020]
【The invention's effect】
As described above, according to the present invention, from the exhaust gas generated by the combustion of waste or the like, the desalted residue discharged by the dry gas purification process can be effectively used, and not disposed of unnecessarily outside the system, Recycling within the waste treatment system becomes possible.
[Brief description of the drawings]
FIG. 1 is a configuration diagram for explaining an embodiment of the present invention;
FIG. 2 is a system diagram showing an embodiment of a waste treatment apparatus to which the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 1st exhaust gas flow path 11 1st exhaust gas processing means 12 2nd exhaust gas flow path 13 2nd exhaust gas processing means 15 Slaked lime 16 Auxiliary agent 17 Supply path 18 Induction fan 19 White smoke prevention device 21 Chimney 30 Desalination residue Treatment means 31 Desalination residue 32 Mixing tank 33 Dehydrator 34 Detoxification cake 35 Dryer 36 Solid salt compound 37 Evaporated moisture 38 Water 50 Waste treatment device 51 First conveyor 52 Crusher 53 Second conveyor 54 Screw feeder 55 Pyrolysis reactor 56 Discharge device 57 Cooling device 58 Separation device 59 Container 60 Pulverizer 61 Blower 62 Burner 63 Combustion melting furnace 64 Crushing and pulverizer 65 Heater 66 Slag outlet 67 Water tank 68 Heat exchanger 69 Waste heat boiler 70 Power generation Machine 71 First exhaust gas treatment device 72 Dust 73 Second exhaust gas treatment device 74 Desalination residue 75 Induction blower 76 Chimney 77 Blower 78 Desalination desulfurization agent 80 Desalination residue treatment means 81 Water 82 Detoxification cake 83 Solid salt compound 84 Evaporated moisture a Waste b Pyrolysis residue c Combustion component d Incombustibility component e Incombustibility waste f Melting Slag g Slag G ₁ Pyrolysis gas G ₂ Combustion exhaust gas G ₃ Exhaust gas L ₁ Heating air line L ₂ Pyrolysis gas line L ₃ Combustion component supply line L ₄ Combustion air supply line L ₅ Non-combustible waste supply line L ₆ exhaust gas line L ₇ exhaust gas recirculation line L ₈ heated air supply line L ₉ dust circulation line L ₁₀ dust supply line

Claims (3)

The dust from the combustion melting furnace that combusts combustible materials such as waste and is discharged as molten slag is removed by the first exhaust gas treatment means, and then the desalted desulfurizing agent is added to the exhaust gas from which the dust has been removed. After adding the above, the desalted residue is discharged by a second exhaust gas treatment means that performs desalting and desulfurization treatment in a dry manner, water is added to the desalted residue, mixed , the chemical is added, and the above is filtered. A method for recovering an active ingredient from a desalting residue, wherein heavy metal contained in the desalting residue is removed, and filtered water is evaporated to dryness to recover the active ingredient. Wherein the water added to the desalination residue, recovery method of the active ingredient according to claim 1 which comprises using cooling water of the molten slag generated the combustible material by burning melted. A pyrolysis reactor that pyrolyzes waste to produce pyrolysis gas and a pyrolysis residue mainly composed of nonvolatile components, and after separating the pyrolysis residue into a combustible component and a non-combustible component A combustion melting furnace for supplying and combusting the pyrolysis gas and the combustible component to discharge molten slag and exhaust gas; and a first exhaust gas treatment for removing dust in the exhaust gas discharged from the combustion melting furnace A demineralization / desulfurization agent adding means for adding a demineralization / desulfurization agent to the exhaust gas discharged from the first exhaust gas treatment device; and the desulfurization / desulfurization treatment of the exhaust gas to which the demineralization / desulfurization agent has been added. A dry waste treatment apparatus comprising a second exhaust gas treatment device that discharges a desalted residue, wherein the desalted residue is used to recover an active ingredient from the desalted residue by the recovery method according to claim 1 or 2. Features of providing processing means Waste processing apparatus that.

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