Process and apparatus for eliminating dioxins
First Claim
1. A process for eliminating dioxins, which are generated from a refuse incinerator and have a structure such that two unit substances having a benzene nucleus are bound together via one or two oxygen atoms and at least one chlorine atom is bound to at least one benzene nucleus, from a mixed gas composed of smoke and ash carrying dioxins adhering thereto, which process comprises the steps of:
- passing the above mixed gas through a particulate matter separator and thus passing the mixed gas through a water curtain to thereby cause the dioxin-entraining ash to be taken up in water and discharging only harmless smoke thus separated alone into the atmosphere, separating the resulting mixture of water and dioxin-carrying ash into dioxin-carrying ash and water in a separator, washing the dioxin-carrying ash separated in the above manner with washing water to thereby elute the oleaginous dioxins entrained by the ash to give an emulsion-like oil-water mixture, and separating the resulting mixture, by means of a separator, into ash, which is now dioxin-free, and the emulsion-like oil-water mixture in which dioxins are dissolved, washing the dioxin-free ash first with acidified water, then with alkaline washing water and further with neutral water, to give moist ash and aqueous washings and recovering the ash, combining the water separated from the above-mentioned dioxin-carrying ash, the dioxin-containing emulsion-like oil-water mixture and the above washings and admixing the whole mixture with a pH adjusting solution, to give a liquid mixture, electrolyzing the liquid mixture in a primary electrolyzer equipped with an anode and a cathode to thereby decompose dioxin components into unit benzene nucleus substances and substitute a hydrogen atom(s) for the chlorine atom(s) on the unit benzene nucleus substances, to give a harmless aromatic oil fraction and gaseous chlorine in the upper layer of the electrolyzer, and separating and recovering the aromatic oil fraction and gaseous chlorine, respectively, transferring the dilute liquid mixture remaining after recovery of the aromatic oil fraction and gaseous chlorine and now mainly consisting of water to a secondary electrolyzer equipped with a metal anode and a metal cathode and electrolyzing the mixture therein to generate hydrogen at the cathode as a result of electrolysis of water and a metal hydroxide at the anode, thus decomposing the remaining trace amounts of dioxin components into unit benzene nucleus substances and substituting a hydrogen atom(s) for the chlorine atom(s) on the unit benzene nucleus substances, to give a harmless aromatic oil fraction and a trace amount of gaseous chlorine in the upper layer, and separating and recovering the harmless liquid aromatic oil fraction, allowing the above metal hydroxide to take up those substances that are contained in the dilute liquid mixture as well as the above-mentioned trace amount of gaseous chlorine and thus precipitate in the bottom layer, recovering this precipitate and discharging or draining the middle layer electrolysis liquid.
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Accused Products
Abstract
For eliminating dioxins from soot containing dioxins adhering to incineration ash by decomposing them, in an easy and simple manner and at low cost, into a harmless and useful oil and water and recovering the oil and water, a mixed gas 3 composed of smoke and dioxin-entraining ash is passed through a particulate matter separator 6, where the mixed gas passes through a curtain of water 5 to cause the dioxin-entraining ash to be taken up in water. The ash-water mixture is separated into ash and water on a centrifuge 12. The ash is washed with washing water 22 to elute the oleaginous dioxins entrained by the ash to give an emulsion-like oil-water mixture and the resulting mixture is separated, by means of a centrifuge 23, into ash and the emulsion-like oil-water mixture in which dioxins are dissolved. This ash is washed first with acidified water 26, then with alkaline washing water 28 and further with neutral water 29, followed by separation into moist ash and aqueous washings. The water separated from the ash, the dioxin-containing emulsion-like oil-water mixture and the above washings are combined and admixed with a pH adjusting solution 42, to give a liquid mixture. This liquid mixture is electrolyzed in a primary electrolyzer 43 equipped with an anode (carbon 9) and a cathode (stainless steel 10) to thereby decompose dioxin components into unit benzene nucleus substances and substitute a hydrogen atom(s) for the chlorine atom(s) on the unit benzene nucleus substances, to give a harmless aromatic oil fraction and gaseous chlorine. The resulting dilute liquid mixture mainly consisting of water is transferred to and electrolyzed in a secondary electrolyzer 33 in which aluminum is used as the anode material and stainless steel as the cathode material, to generate hydrogen at the anode by electrolysis of water and metal hydroxides by electrolysis of aluminum. The remaining trace amounts of dioxin components are thus decomposed into unit benzene nucleus substances, and a hydrogen atom(s) is(are) substituted for the chlorine atom(s) on the unit benzene nucleus substances, to give an aromatic oil fraction and a trace amount of gaseous chlorine. The metal hydroxide takes up those trace substances that are contained in the liquid mixture as well as the trace amount of gaseous chlorine and precipitates in the lower layer. This precipitate and the aromatic oil fraction are recovered.
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Citations
10 Claims
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1. A process for eliminating dioxins, which are generated from a refuse incinerator and have a structure such that two unit substances having a benzene nucleus are bound together via one or two oxygen atoms and at least one chlorine atom is bound to at least one benzene nucleus, from a mixed gas composed of smoke and ash carrying dioxins adhering thereto, which process comprises the steps of:
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passing the above mixed gas through a particulate matter separator and thus passing the mixed gas through a water curtain to thereby cause the dioxin-entraining ash to be taken up in water and discharging only harmless smoke thus separated alone into the atmosphere, separating the resulting mixture of water and dioxin-carrying ash into dioxin-carrying ash and water in a separator, washing the dioxin-carrying ash separated in the above manner with washing water to thereby elute the oleaginous dioxins entrained by the ash to give an emulsion-like oil-water mixture, and separating the resulting mixture, by means of a separator, into ash, which is now dioxin-free, and the emulsion-like oil-water mixture in which dioxins are dissolved, washing the dioxin-free ash first with acidified water, then with alkaline washing water and further with neutral water, to give moist ash and aqueous washings and recovering the ash, combining the water separated from the above-mentioned dioxin-carrying ash, the dioxin-containing emulsion-like oil-water mixture and the above washings and admixing the whole mixture with a pH adjusting solution, to give a liquid mixture, electrolyzing the liquid mixture in a primary electrolyzer equipped with an anode and a cathode to thereby decompose dioxin components into unit benzene nucleus substances and substitute a hydrogen atom(s) for the chlorine atom(s) on the unit benzene nucleus substances, to give a harmless aromatic oil fraction and gaseous chlorine in the upper layer of the electrolyzer, and separating and recovering the aromatic oil fraction and gaseous chlorine, respectively, transferring the dilute liquid mixture remaining after recovery of the aromatic oil fraction and gaseous chlorine and now mainly consisting of water to a secondary electrolyzer equipped with a metal anode and a metal cathode and electrolyzing the mixture therein to generate hydrogen at the cathode as a result of electrolysis of water and a metal hydroxide at the anode, thus decomposing the remaining trace amounts of dioxin components into unit benzene nucleus substances and substituting a hydrogen atom(s) for the chlorine atom(s) on the unit benzene nucleus substances, to give a harmless aromatic oil fraction and a trace amount of gaseous chlorine in the upper layer, and separating and recovering the harmless liquid aromatic oil fraction, allowing the above metal hydroxide to take up those substances that are contained in the dilute liquid mixture as well as the above-mentioned trace amount of gaseous chlorine and thus precipitate in the bottom layer, recovering this precipitate and discharging or draining the middle layer electrolysis liquid. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for eliminating dioxins, which are generated from a refuse incinerator and have a structure such that two unit substances having a benzene nucleus are bound together via one or two oxygen atoms and at least one chlorine atom is bound to at least one benzene nucleus, from a mixed gas composed of smoke and ash carrying dioxins adhering thereto, which apparatus comprises:
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a particulate matter separator into which the above mixed gas is introduced to thereby pass the mixed gas through a water curtain for causing the dioxin-entraining ash to be taken up in water and which discharges only the harmless smoke thus separated alone into the atmosphere, a first separator for separating the resulting mixture of water and dioxin-carrying ash into dioxin-carrying ash and water, washing water for washing the dioxin-carrying ash separated to thereby elute the oleaginous dioxins entrained by the ash to give an emulsion-like oil-water mixture, a second separator for separating the dioxin-freed ash and the emulsion-like oil-water mixture containing dioxins dissolved therein from each other, acidified water, alkaline washing water and neutral water, each to be used for washing the dioxin-freed ash in that order and a third separator for separating the mixture resulting from each washing into moist ash and washings for recovering the moist ash, a pH adjusting solution to be admixed with a liquid phase resulting from combining together the water separated from said dioxin-carrying ash, the dioxin-containing emulsion-like oil-water mixture and the respective washings to give a liquid mixture having a predetermined pH, a primary electrolyzer equipped with an anode and a cathode for electrolyzing said mixture to thereby decompose dioxin components into unit benzene nucleus substances and substitute a hydrogen atom(s) for the chlorine atom(s) on the unit benzene nucleus substances for forming a harmless aromatic oil fraction and gaseous chlorine in the upper layer thereof, first recovery means for separating and recovering the gaseous chlorine from the electrolysis mixture formed in said primary electrolyzer and second recovery means for separating and recovering said aromatic oil fraction, a secondary electrolyzer equipped with a metal anode and a metal cathode for electrolyzing the dilute liquid mixture remaining after removal/recovery of the aromatic oil fraction and gaseous chlorine and now mainly consisting of water to thereby generate hydrogen at the cathode as a result of electrolysis of water and a metal hydroxide at the anode and decompose the remaining trace amounts of dioxin components into unit benzene nucleus substances and substitute a hydrogen atom(s) resulting from the hydrolysis of water for the chlorine atom(s) on the unit benzene nucleus substances, to give a harmless aromatic oil fraction and a trace amount of gaseous chlorine in the upper layer, and cause said metal hydroxides to take up the trace amount of substances that are still contained in the dilute liquid mixture and said trace amount of gaseous chlorine and precipitate in the bottom layer, third recovery means for separating and recovering the harmless aromatic oil from the water in the secondary electrolyzer and fourth recovery means for recovering the metal hydroxides. - View Dependent Claims (7, 8, 9, 10)
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Specification
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- Resources
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Current AssigneeYukimasa Satoh
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Original AssigneeYukimasa Satoh
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InventorsSatoh, Yukimasa
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Granted Patent
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Time in Patent OfficeDays
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Field of Search
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US Class Current204/242
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CPC Class CodesA62D 2101/28 containing oxygen, sulfur, ...A62D 2203/10 Apparatus specially adapted...A62D 3/115 Electrolytic degradation or...C02F 1/4672 by electrooxydationC02F 2101/32 Hydrocarbons, e.g. oilC02F 2101/366 Dioxine; FuranC02F 2103/18 from the purification of ga...
