JP3730794B2 - Method and apparatus for decomposing a hardly decomposable substance - Google Patents

Description

として分解処理される。
【００４０】
図４は酸化カルシウムによるフロンＲ−１２分解時の分解率と温度の関係を示すグラフであり、図中に記載したようにフロンの流量は２ｋｇ／ｈ、水は２０ｇ／ｍｉｎ、ＣａＯは２ｋｇとして反応させた例である。図４によれば反応器内の温度が４００℃に達した際に分解率はほぼ１００％となる。図５は同じく分解率と時間（分）との関係を示すグラフであり、温度は４００℃及び３００℃としたところ、４００℃の場合には約２０分で分解率が１００％に達していることが判明した。
【００４１】
フロンＲ−２２の場合には、分解反応の基本式は下記の（８）式又は（９）式で表わされる。

【００４２】
実際には（８）式の反応の方が優先的に生じており、反応後のガス中にメタンＣＨ₄が多く含まれている。上記の反応によって生じたＨＣｌ，ＨＦの中和反応が前記（２）〜（５）式に基づいてほぼ同時に行われる。また、反応器４２の内部温度が４００℃以上になると、以下の（１０）〜（１２）式の反応が起こる。

【００４３】
しかし反応後のガス中にメタンＣＨ₄が多く含まれていることから全体として（８）（１０）式の反応が主体であるものと思慮される。
【００４４】
図６は酸化カルシウムによるフロンＲ−２２分解時の分解率と温度の関係を示すグラフであり、図中に記載したようにフロンの流量は２ｋｇ／ｈ、水は２０ｇ／ｍｉｎ、ＣａＯは２ｋｇとして反応させた例である。図６によればフロンＲ−１２の場合と同様に反応器内の温度が４００℃に達した際に分解率はほぼ１００％となる。図７は同じく分解率と反応時間（分）との関係を示すグラフであり、温度が４００℃の場合には分解率は当初から１００％に達している。また、初期温度が３００℃程度の低温での反応時には、反応時間３０分で電源をオフにしても温度が除々に上昇し、反応時間が１００分で５００℃に達していることが判明した。これは酸化カルシウムとフロンＲ−２２の分解反応が発熱反応であることを示している。
【００４５】
フロンＲ−１３４ａの場合の分解反応の基本式は下記の（１３）〜（１６）式で表わされる。

【００４６】
生成ガスの分析から（１４）（１５）式が多く生じており、次いで（１３）が生じている。（１６）式は稀に生じる程度である。更に反応器内の温度が３００℃以上に高くなると、下記の反応が僅かに生じる。

【００４７】
図８は酸化カルシウムによるフロンＲ−１３４ａ分解時の分解率と温度の関係を示すグラフであり、図中に記載したようにフロンの流量は２ｋｇ／ｈ、水は２０ｇ／ｍｉｎ、ＣａＯは２ｋｇとして反応させた例である。図８によればフロンＲ−１２の場合と同様に反応器内の温度が４００℃に達した際に分解率はほぼ１００％となる。図９は同じく分解率と反応時間（分）との関係を示すグラフであり、温度が４００℃の場合には分解率は当初から１００％に達している。また、初期温度が３００℃程度の低温での反応時には、反応時間６０分で電源をオフにしても温度が除々に上昇し、反応時間が１００分で５００℃に達していることが判明した。これは酸化カルシウムとフロンＲ−１３４ａの分解反応が発熱反応であることを示している。
【００４８】
フロンＳＦ６（六フッ化硫黄）の場合の分解反応の基本式は下記の（２０）（２１）式で表わされる。このフロンＳＦ６は絶縁用ガスであり、通常高圧の電力スイッチの中に封入されている。
３ＣａＯ＋ＳＦ₆＋Ｈ₂Ｏ → ３ＣａＨ₂＋Ｈ₂ＳＯ₄………………… （２０）
ＳＦ₆＋ＣａＯ＋３Ｈ₂Ｏ → ＣａＳＯ₄＋６ＨＦ…………………… （２１）
【００４９】
上記（２０）式が主体となっている。この時に発生するＨ₂ＳＯ₄は
ＣａＯ＋Ｈ₂ＳＯ₄ → ＣａＳＯ₄＋Ｈ₂Ｏ………………………………（２２）
により中和される。
【００５０】
上記の説明はフロンに関しての反応式であるが、その他のハロン、トリクロロエチレン、トリクロロタン等のハロゲン化物、ベンゼン、モノクロロベンゼン等のベンゼン核を持つ有機化合物についても同様な反応式により分解することができる。
【００５１】
分解反応に直接関係ない反応として下記の（２３）式が生じる。
ＣａＯ＋Ｈ₂Ｏ → Ｃａ（ＯＨ）₂………………………………………（２３）
これは酸化カルシウムが水と反応して水酸化カルシウムを生成する発熱反応であり、Ｈ₂Ｏとして水蒸気を用いると高温の蒸気が自然に得られてＣａＯによる分解に熱源を必要としないケースがある。また、反応器３３の放熱機構を工夫することにより、初期加熱以後は自己発熱による加熱が可能となり、自然に分解反応が進行する。
【００５２】
本実施の形態では水タンク３４から反応器３３に水分を加えているが、反応自体には水分は必ずしも必要としないものであって、例えば前記（６）式に記載した反応が進行する。この場合にはＣａＯを細かく砕いてフロンとの接触面積を大きくすることが肝要であり、ＣａＯの内部にまで反応が浸透しないことによって一定時間後は内部のＣａＯを砕いて未反応のＣａＯを表面に出す必要がある。
【００５３】
反応器３３に水分を加えた場合には、ＣａＯとの反応が内部まで浸透して前記（２３）式による発熱反応が進行する。そしてＣａＯがなくなるまで継続することが確認された。この場合には反応器３３の容器外部を空冷するとか水冷する必要が有る。
【００５４】
次に前記反応式（１）〜反応式（２３）についての反応熱バランスシートを表１〜表２３に示す。表はコンピュータのデータベースを用いてシミュレーションして得たものである。
【００５５】
【表１】

【００５６】
表１の下記反応式は前記反応式（１）に対応しており、表２〜表２３の反応式もそれぞれ前記反応式（２）〜（２３）に対応している。

【００５７】
表１〜表２３において、（ｇ）はガス状であることを示し、（ｌ）は液体状であることを示し、他は固体状であることを示している。各表中のＴは反応温度（℃）、ｄｅｌｔａＨ（ｋｃａｌ）中の発熱量の符号が（−）の場合には発熱反応であり、（＋）の場合は吸熱反応であることを示している。ｄｅｌｔａＳ（ｃａｌ）はエントロピーを示し、ｄｅｌｔａＧ（ｋｃａｌ）はギブスの自由エネルギーで反応の進む方向を示し、符号の（−）は反応式の左から右へ（→）のように進むことを示している。Ｋは反応式の左の量と右の量の比率であり、表１中の３.２０３Ｅ＋０６７は３.２０３×１０⁶⁷倍右側の物質ができることを示している。以下表２〜表２３についても同様である。
【００５８】
【表２】

【００５９】
【表３】

【００６０】
【表４】

【００６１】
【表５】

【００６２】
【表６】

【００６３】
【表７】

【００６４】
【表８】

【００６５】
【表９】

【００６６】
【表１０】

【００６７】
【表１１】

【００６８】
【表１２】

【００６９】
【表１３】

【００７０】
【表１４】

【００７１】
【表１５】

【００７２】
【表１６】

【００７３】
【表１７】

【００７４】
【表１８】

【００７５】
【表１９】

【００７６】
【表２０】

【００７７】
【表２１】

【００７８】
【表２２】

【００７９】
【表２３】

【００８０】
【発明の効果】
以上詳細に説明したように、本発明によればフロンガスとかベンゼン核を持つ有機化合物，更にトリクロロエチレン，ハロン，ＳＦ６等のその他のハロゲン化物等の難分解物質を酸化カルシウムを利用して分解処理できるとともにＣａＯによる中和反応がほぼ同時に起きることにより、プラズマ法とか燃焼法のような他の分解方法を用いた分解過程で生成する強酸による容器とか配管類の腐食が発生せず、分解処理装置の寿命が長く、又大容量の中和設備や大量の中和剤を必要としないという効果が得られる。特に反応が発熱反応であるため、初期加熱だけ行えば反応開始と同時に加熱源を遮断しても分解反応が継続することになり、電力の節約にも資することができる。
【００８１】
特に水熱反応のように高温高圧条件を維持する必要がなく、機械的な強度に耐えるための設計は不要であり、使用する材料は限定されない。装置は機構的にも簡易であって、被分解物質の種類によって構造を変える必要がなく、操作上のコントロールは容易である。
【００８２】
また、反応器内を高温に維持する必要がないため、エネルギーコストを低廉化することができる。また、酸性物質によって容器とか管路が腐食される惧れがない。また、容器等に含まれている鉄分が酸によって腐食されて耐久性が低下する現象を防止することができる。
【００８３】
従来から知られている触媒法の場合には、触媒の酸化等による劣化が生じる難点があるのに対して、本発明の場合には触媒を使用していないために上記の問題点はなく、しかもフロンのみならず他のハロゲン化物とかベンゼン核を持つ有機物にも適用可能である。
【００８４】
酸化カルシウム自体は安価であり、中和剤としても使用可能であるため、ランニングコストは低廉化されるという利点が得られる。分解反応によって生成される酸性ガスは酸化カルシウムによって生成とほぼ同時に反応器の中で中和されて反応器外に排出されることがないため、従来のように強い酸性物質によって管路が腐食されることがない。そして、反応器から排出されるガスはＣＯ₂，ＣＨ₄，Ｈ₂，ＣＯ等が成分であるため、管路等の分解処理装置を腐食させることがなく、冷却した後に可燃性ガスを燃焼させて排出させることができる。また、反応によって生成される反応後の処理物であるＣａＦ₂，ＣａＣｌ₂，ＣａＳＯ₄等は固体であるため、反応器から取り出して容易に処理することができ、リサイクルも可能となる。更に装置の構成は、従来の装置に較べて比較的簡単であり、装置自体のスケールアップとかスケールダウンを容易に行うことができる。
【００８５】
従って本発明によれば、環境汚染物質であるフロンガスとかベンゼン核を持つ有機化合物，更にトリクロロエチレン，ハロン，ＳＦ６等のその他のハロゲン化物等の難分解物質の分解を行う際に、高温高圧に耐える機械的な強度が要求されることがなく、しかも強酸に起因する配管とか排出弁の腐食を防止し、材料費とかランニングコストが低廉化された難分解物質の分解処理方法及びその装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の基本的実施形態を示すシステム図。
【図２】本実施形態で用いた反応器の側断面図。
【図３】図２の平面図。
【図４】フロンＲ−１２分解時の分解率と温度の関係を示すグラフ。
【図５】フロンＲ−１２分解時の分解率と時間との関係を示すグラフ。
【図６】フロンＲ−２２分解時の分解率と温度の関係を示すグラフ。
【図７】フロンＲ−２２分解時の分解率と時間との関係を示すグラフ。
【図８】フロンＲ−１３４ａ分解時の分解率と温度の関係を示すグラフ。
【図９】フロンＲ−１３４ａ分解時の分解率と時間との関係を示すグラフ。
【図１０】従来の水熱反応処理による環境汚染物質の処理装置を示すシステム図。
【図１１】従来の他の水熱反応処理による環境汚染物質の処理装置を示すシステム図。
【符号の説明】
３１…被分解処理物
３２…流量調整弁
３３…反応器
３４…水タンク
３５…水供給ポンプ
３６…蒸発器
３７…内部ヒータ
３９…（酸化カルシウムの）投入口
４０…酸化カルシウム
４２…冷却器
４３…中和装置
４４…燃焼装置
４５…排出口
整理番号 Ｐ２９０９[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method and apparatus for decomposing a hardly decomposable substance such as an environmental pollutant, and in particular, reacting an organic compound having chlorofluorocarbon or a benzene nucleus, and other halides such as trichlorethylene, halon, and SF6 with calcium oxide. The present invention relates to a treatment method and an apparatus for decomposing and detoxifying the acid gas and neutralizing acid gas produced by the decomposition almost simultaneously.
[0002]
[Prior art]
It has been pointed out that chlorofluorocarbon gas, which has been used as a refrigerant or spray agent, and halon gas, which has been used as a digestive agent, are environmental pollutants. Various countermeasures have been proposed. For example, hydrothermal reaction methods, incineration methods, explosion reaction decomposition methods, microbial decomposition methods, ultrasonic decomposition methods, plasma reaction methods, and the like have been proposed for chlorofluorocarbon gas treatment methods.
[0003]
Among these treatment methods, the hydrothermal reaction method is not limited to chlorofluorocarbons, etc., but is versatile for all degradable substances mainly composed of organic solvents such as trichlene, waste oil, dioxin, PCB, manure, etc. It is attracting attention as a processing method. In this hydrothermal reaction method, for example, Freon gas can be decomposed into safe substances such as sodium chloride and carbon dioxide.
[0004]
Regarding equipment for realizing the hydrothermal reaction method, processing experiments using an autoclave in the laboratory, for example, the mixing ratio of caustic soda solution, ethanol, chlorofluorocarbon solution, temperature setting value, pressure setting value and reaction time setting Experiments have been conducted on values, but the normal hydrothermal reaction is 100 to 250 kg / cm at 300 to 450 ° C. ² The high temperature and high pressure conditions are maintained.
[0005]
The applicant of the present application previously proposed a method and apparatus for treating environmental pollutants by hydrothermal reaction treatment according to Japanese Patent Application No. 6-204519. The contents will be briefly described based on the flow of the chlorofluorocarbon treatment system shown in FIG. 10. A tank 1 contains a mixed solution of chlorofluorocarbon, caustic soda, and ethanol, which is heated from a pipe 4 through a pump 2 and a flow meter 3. It is sent to the exchanger 5, reacted in the hydrothermal reactor 6, then sent again to the cooler 7 through the heat exchanger 5, and sent from the cooler 7 to the separator 9 via the pressure regulating valve 8 for flow rate control. Then, the water is separated into clean water and clean materials by the separator 9. The tank 1a, the pump 2a, and the flow meter 3a shown in the figure are systems used in such a case because they may be gasified at room temperature depending on the type of the fluorocarbon gas.
[0006]
Further, the applicant of the present application has proposed a method and apparatus for treating environmental pollutants by other hydrothermal reaction treatment in Japanese Patent Application No. 8-340560. The contents will be described based on the flow of the chlorofluorocarbon treatment system in FIG. 11. 11 is a tank to be decomposed such as chlorofluorocarbon, 12 is a pump to be decomposed, 13 is a water tank as a solvent, 14 is a water pump, and 15 is a heater. In this heater 15, an internal heater 16 and an external heater 17 are arranged, and in the heater 15, a plurality of iron plates 18, 18 are arranged as substances that react with superheated steam to generate hydrogen. Yes. Reference numeral 19 denotes a reactor, which has a function of performing a decomposition treatment by reacting a material to be decomposed with superheated steam and hydrogen of a solvent for a predetermined time while maintaining a predetermined temperature. The reactor 19 is provided with internal heaters 20 and 20 and external heaters 21 and 21, and iron plates 18 and 18 are also provided in the reactor 19. In place of the iron plate 18, carbon, carbon steel, or the like can be used as a substance that reacts with superheated steam to generate hydrogen.
[0007]
Unlike the conventional high-pressure hydrothermal reactor, the reactor 19 has an open-type configuration in which no pressure is forcedly applied, and a slight pressure is naturally generated by superheated steam, resulting in a pressure gradient. Transfer the material to be decomposed. A cooler 22 is provided with a pipe 23 communicating with the pipe led out from the reactor 19. Reference numeral 24 is an inlet for cooling water, and 25 is an outlet for cooling water. 26 is a gas-liquid separator, and 27 is a neutralization device. The other end of the pipe 28 led out from the cooler 22 is inserted into the gas-liquid separator 26 and led out from the gas-liquid separator 26. The other end of the pipe 29 is inserted into the neutralizer 27. Reference numeral 30 denotes a treatment liquid discharge port.
[0008]
According to such an apparatus, chlorofluorocarbon is introduced into the decomposition target tank 11 and the decomposition target pump 12 and the water pump 14 are activated, so that chlorofluorocarbon and water as a solvent are sent to the heater 15 through the pipe. Mixed in proportion. Then, the superheated steam is generated by heating the internal heater 16 and the external heater 17 arranged in the heater 15 in advance to 500 ° C. to 750 ° C. When the iron plates 18 and 18 are heated to substantially the same temperature in the heater 15, the superheated steam comes into contact with the iron plate 18 to generate magnetite and hydrogen.
[0009]
The produced hydrogen has a very strong reducing power and binds to many substances to decompose the material to be decomposed. The reactor 19 is also heated and maintained in advance so as to maintain the temperature of the superheated steam by driving the internal heaters 20 and 20 and the external heaters 21 and 21, and the above reaction proceeds due to the presence of the iron plate. Since superheated steam is also present in the reactor 19 in the same atmosphere, hydrolysis also takes place concurrently, and a complex decomposition reaction proceeds. Along with this, the decomposition rate of the object to be decomposed is increased and the decomposition rate is improved.
[0010]
In the cooling device 22, the cooling water is supplied from the cooling water inlet 24 and flows out from the outlet 25, whereby the gas of the decomposition product decomposed in the pipe 23 communicating with the reactor 19 is cooled and liquefied. The temperature in the cooler 22 may be a temperature at which the decomposition product gas can be liquefied. The discharged liquid enters the gas-liquid separator 26 through the pipe 28, the gas-liquid is separated and the liquid material flows into the neutralizing device 27, is subjected to a predetermined neutralization process, and is discharged from the discharge port 30. It is stored in an external drainage tank.
[0011]
This configuration is suitable for the case of decomposing a solid decomposition target other than fluid or gas, such as PE, plastic, rubber, wood, paper, etc. In addition to supplying the product to the reactor 19, the reactor 19 is provided with means for transferring a material to be decomposed such as a feeder.
[0012]
On the other hand, in Japanese Examined Patent Publication No. 58-56396, superheated steam obtained by a superheated steam generator is injected into a cracking furnace, and waste tires are separated into cracked gas, carbon residues and beat wires and reused. A thermal decomposition apparatus is disclosed. Further, JP-A-3-12220 discloses a method for hydrolyzing a chlorofluoroalkane (fluorocarbon) to a harmless compound by contacting it with a catalyst made of activated carbon supporting iron oxide in the presence of water vapor. Yes.
[0013]
[Problems to be solved by the invention]
As described above, the hydrothermal reactor 6 in FIG. 10 must maintain high-temperature and high-pressure conditions. Therefore, the structure of the pressure regulating valve 8 is complicated and expensive, and further, mechanical strength for use at high temperature and high pressure, for example, It is difficult to design to withstand tensile stress and thermal stress, and there is a problem that the material to be used is limited. Further, the mechanism for pumping and discharging the solid-liquid mixture under high temperature and high pressure is complicated, and there is a problem that it is difficult to control the operation because the structure needs to be changed depending on the type of the substance to be decomposed. In addition, the pipe 4 may be damaged during operation due to the high pressure, which leaves difficulties in terms of ensuring safety.
[0014]
On the other hand, in the superheated steam reaction method shown in FIG. 11, the hardly decomposed substance becomes superheated steam together with the solvent, and is further heated in the reactor 19 to become superheated steam whose temperature is increased only at normal pressure. It reacts with iron, carbon, carbon steel, etc. when it passes through the reaction time to generate hydrogen, and it is possible to decompose difficult-to-decompose substances by reduction reaction with hydrogen and hydrolysis reaction with superheated steam. However, it is necessary to maintain the inside of the reactor 19 at a high temperature of 650 ° C. or higher, and there is a problem that the energy cost is slightly high, and a strong acid such as HCl or HF is generated in the reaction gas. The problem remains that the pipes leading to the reactor 19 and the neutralization device 27 are corroded.
[0015]
In addition, steel plates, carbon, carbon steel, etc. are used as reaction aids, but when iron plates are used, FeCl ₂ Or FeF ₂ May precipitate as a solid, which may cause clogging of the pipeline. When carbon is used, clogging of pipes does not occur, but there is a problem that the iron content in the container etc. gradually corrodes and the durability is lowered, and the carbon itself is expensive and consumed. There is a problem that the running cost is adversely affected.
[0016]
In particular, when a strong acid is liquefied, the corrosion rate increases, so it is necessary to use Teflon or PVC for the pipe line. However, since these materials are vulnerable to heat, there is a problem that the device design becomes difficult. Further, there is a problem that a large capacity is required as the neutralizing device 27 and a large amount of the neutralizing agent is used, so that a large cost is required for the equipment and the medicine.
[0017]
In the thermal decomposition apparatus described in the above Japanese Patent Publication No. 58-56396, although waste tires can be separated into residues such as cracked gas and carbon, the efficient decomposition of the hardly decomposed substances such as Freon targeted by the present invention There is no mention of any serious degradation and the degradation of these substances cannot be carried out. Furthermore, in the means for hydrolyzing chlorofluorocarbon by contacting it with a catalyst in the presence of water vapor as described in JP-A-3-12220, decomposition of substances other than chlorofluorocarbon, for example, organic compounds having a benzene nucleus or other industrial waste In addition, depending on the type of fluorocarbon, sufficient effects in terms of decomposition efficiency cannot be obtained, the catalyst used lacks durability, and the mixture of fluorocarbon and oil can be decomposed. There is a difficulty of not.
[0018]
Therefore, the present invention eliminates the above-mentioned problems in a system for decomposing refractory substances such as environmental pollutants such as chlorofluorocarbon, halogenated substances such as trichlorethylene, halon, and SF6, and organic compounds having a benzene nucleus, and provides high temperature and pressure. It is an object of the present invention to provide a method and apparatus for decomposing a hardly decomposable substance, which does not require mechanical strength to withstand, and does not corrode piping or discharge valves due to strong acid, and has reduced material costs and running costs. It is what.
[0019]
[Means for Solving the Problems]
The present invention achieves the above object. , Covered The mixture of the decomposed product and solvent is contacted with calcium oxide in the reactor, and the acidic substance produced by the reaction is neutralized in the reactor almost at the same time as the product is made harmless. Then, the reacted gas and liquid components that have undergone the decomposition treatment are taken out from the reactor and sent to the cooler to cool the gas to be decomposed, and the cooled gas is neutralized by a neutralizer to render it harmless. Degradation treatment method for persistent substances , And means for performing a combustion treatment of combustible components using a combustion device after neutralization treatment using a neutralization device I will provide a.
[0020]
Also, calcium oxide is introduced inside, a reactor equipped with an inlet for the substance to be decomposed, an inlet for the solvent and an internal heater, a cooler for cooling the high-temperature gas of the object to be decomposed, and produced by the reaction It consists of a neutralization device that neutralizes the detoxified material and renders it harmless. After the contacted reaction between the substance to be decomposed and calcium oxide in the presence of a solvent while heating in the reactor, the high-temperature gas of the object to be decomposed Is cooled by a cooler, Neutralizes a small amount of residual acidic substances with a neutralizer to make them harmless. Deployed a decomposition device for difficult-to-decompose substances, and a combustion device that combusts combustible components after neutralization by a neutralizer I will provide a.
[0021]
According to such decomposition method and apparatus, chlorofluorocarbon, organic compounds having a benzene nucleus and other halogenated substances such as halides react with calcium oxide in the reactor to become acidic substances and harmless inorganic substances. Since it is further neutralized by reacting with calcium oxide, that is, neutralized and detoxified in the reactor almost simultaneously with the production, the pipeline is corroded by a strong acidic substance as before. There is nothing to do. Therefore, the lifetime of the decomposition treatment apparatus is long, and a large-capacity neutralization facility and a large amount of neutralizing agent are not required. Further, the reaction proceeds continuously by using water as a solvent, and the initial decomposition reaction is promoted by arranging an internal heater in the reactor.
[0022]
In addition, by disposing the cooler, after the gas of the decomposition-treated material obtained from the reactor is cooled, a small amount of residual acidic substance is neutralized by the neutralizer as necessary and harmless. It becomes. In addition, since this residual acidic substance is trace amount, it does not corrode a pipe line. Furthermore, after performing the neutralization process with the neutralization apparatus, the combustible component is combusted with the combustion apparatus, whereby the hardly decomposable substance can be safely and reliably decomposed.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of a method for decomposing a hardly decomposable substance and its apparatus according to the present invention will be described below with reference to the drawings. In view of the problems in the hydrothermal reaction treatment described above, the inventor of the present application tried various improvement experiments, and as a result, the substance to be decomposed such as Freon was reacted with calcium oxide (CaO, also called quicklime). The inventor has obtained knowledge that the material to be decomposed can be decomposed without bringing the reactor into a strongly acidic state.
[0024]
The present invention decomposes a hardly decomposable substance including environmental pollutants such as chlorofluorocarbon at normal pressure, and the target hardly decomposable substance is an organic compound having chlorofluorocarbon or benzene nucleus, trichloroethylene, halon, Other halides such as SF6 are targeted, and the state is not particularly limited regardless of whether it is solid, liquid, or gas. In particular, organic halides that are useful but difficult to treat after use and harmful ones such as chlorobenzene, chlorofluorocarbon (halogen carbon compound), dioxins in question, and the like.
[0025]
Further, according to the present invention, not only halides but also benzene rings can be opened. Benzene to be decomposed by the present invention is a basic compound of aromatic hydrocarbon, and C ₆ H ₆ Monochlorobenzene is C ₆ H _Five It is represented by Cl. Examples of organic compounds having a benzene nucleus include phenols. These phenols are a general term for organic compounds in which an OH group is bonded to a benzene nucleus. ₆ H _Five Expressed as OH. In addition, according to the present invention, dioxins having a benzene ring as a skeleton structure, PCB, and the like can be decomposed and rendered harmless.
[0026]
Specific embodiments will be described below. FIG. 1 is a system diagram schematically showing an embodiment of the present invention, in which 31 is a substance to be decomposed such as chlorofluorocarbon, 32 is a flow regulating valve, 33 is a reactor, 34 is a water tank as a solvent, 35 is a water supply pump, and 36 is an evaporator.
[0027]
2 and 3, the reactor 33 is provided with a plurality of internal heaters 37, 37 and a calcium oxide inlet 39. Reference numerals 38 and 38 denote fixing bolts for the lid member 33b of the reactor 33, reference numeral 40 denotes charged calcium oxide, and reference numeral 41 denotes a mounting plate for the calcium oxide. Reference numeral 33c denotes an inflow passage of a mixture of the substance to be decomposed such as CFC and the solvent. In the example of FIG. 2 in which the substance to be decomposed and the solvent are mixed in advance, the water tank 34 and the evaporator 36 in FIG. 1 are omitted. can do.
[0028]
In FIG. 1, reference numeral 42 denotes a cooler, and the cooler 42 is connected to a pipe 33 a led out from the reactor 33. 42a is an inlet for cooling water, and 42b is an outlet for cooling water. 43 is a neutralizing device, 44 is a combustion device, the other end of the pipe 42c led out from the cooler 42 is inserted into the neutralizing device 43, and other than the pipe 43a led out from the neutralizing device 43 The end is inserted into the combustion device 44. Reference numeral 45 denotes a combustion gas discharge port.
[0029]
Calcium oxide (CaO, quicklime) used in the present embodiment is produced by industrially burning limestone, but pure CaO can also be obtained by thermal decomposition of calcium oxalate. Calcium oxide is a colorless crystal with a melting point of 2572 ° C, a boiling point of 2850 ° C, and a density of about 3.3 g / cm. ^Three It reacts by emitting light heat with water to become calcium hydroxide.
[0030]
The operation mode of this embodiment will be described below. Taking the case of using chlorofluorocarbon as an environmental pollutant as an object to be decomposed 31 shown in FIG. 1, for example, calcium oxide 40 is first introduced into the reactor 33 from the inlet 39 of the reactor 33, and then to the subject. The decomposition treatment product 31 is caused to flow into the reactor 33 through the flow rate adjusting valve 32, and at the same time, the water supply pump 35 is activated to allow water as a solvent to enter the reactor 33 from the water tank 34 through the evaporator 36 and piping. It is sent as water vapor and mixed with chlorofluorocarbon at an appropriate ratio. The calcium oxide 40 is stored in the reactor 33 as a predetermined lump or granule.
[0031]
The supply of water may be either liquid or steam. In the configuration of the reactor 33 shown in FIG. 2, the water tank 34 and the evaporator 36 are omitted because the inflow passage 33c for the mixture of the decomposition target substance and the solvent is provided. As shown in FIG. 2, water or water vapor as a solvent may be mixed with the material to be decomposed in advance and supplied to the reactor, or may be supplied individually to the reactor as shown in FIG.
[0032]
When calcium oxide 40 comes into contact with a mixture of chlorofluorocarbon and water as a substance to be decomposed, chlorofluorocarbon is decomposed based on a reaction formula of calcium oxide and chlorofluorocarbon described later, and harmless inorganic substances and acidic substances such as strong acids are generated. These acidic substances are further neutralized and detoxified almost simultaneously with the formation by calcium oxide. Therefore, the pipe line is not corroded by a strong acidic substance as in the prior art. Therefore, the lifetime of the decomposition treatment apparatus is long, and a large-capacity neutralization facility and a large amount of neutralizing agent are not required. The decomposition reaction is promoted by operating the internal heaters 37 during this reaction.
[0033]
Since the reaction in the reactor 33 is accompanied by heat generation, the heating temperature by the internal heaters 37 may be low. In the present embodiment, the upper limit of heating by the internal heaters 37 and 37 is set to 400 ° C., and when the temperature exceeds this temperature, the driving of the internal heaters 37 and 37 is automatically stopped by the action of the thermostat. ing.
[0034]
Theoretically, the reaction between calcium oxide and chlorofluorocarbon proceeds even without water, but it has been experimentally confirmed that the reaction continues due to the presence of water. Water is supplied into the reactor 33 via the evaporator 36.
[0035]
The reacted gas and liquid component stored in the lower part of the reactor 33 are fed into the cooler 42 via the pipe 33a. In the cooler 42, the cooling water is supplied from the inlet 42a of the cooling water and is discharged from the outlet 42b, thereby cooling the high-temperature gas of the decomposed decomposition product and liquefying the water vapor as the solvent. The temperature in the cooler 42 should just be the temperature which can lower | hang the temperature of the gas of a decomposition product to normal temperature. By rapidly cooling in this way, generation of by-products is prevented, so there is no concern about secondary contamination. This cooling is mainly for reducing the temperature to room temperature because the reaction gas generated by the decomposition becomes high temperature (about 400 ° C.). The reaction gas produced by the decomposition is CO. ₂ , CH _Four , H ₂ , CO, and the like are components, so that they are not liquefied even when cooled to room temperature. In addition, the water vapor | steam as a solvent is liquefied by water by cooling. Further, at this time, a small amount of residual acidic substance is dissolved into water, and this is neutralized by a neutralizer described later. Of the reaction gases, CH _Four , H ₂ , CO and the like are combustible combustible gases, and are burned by a combustion apparatus described later.
[0036]
Water as a solvent liquefied by cooling and a reaction gas generated by decomposition flow into the neutralizing device 43 through the pipe 42c, and when there is a residual acidic substance, a predetermined neutralization treatment is performed and further generated. The gas is sent to the combustion device 44, and after combustible components such as methane are combusted, the gas is discharged from the outlet 45. It is also possible to incorporate a heat exchanger into the cooler 42, recover the heat cooled by the heat exchanger, and reuse the recovered heat. CaF produced by the decomposition reaction ₂ , CaCl ₂ , CaSO _Four Since these are solid, they are taken out from the reactor and disposed of.
[0037]
The reaction formula in the case of decomposing chlorofluorocarbon using calcium oxide will be described below. In the case of Freon R-12, the basic formula of the decomposition reaction is represented by the following formulas (1) to (5).
CCl ₂ F ₂ + CaO + 2H ₂ O → 2HCl + 2HF + CaCO _Three ... (1)
CaO + 2HCl → CaCl ₂ + H ₂ O ……………………………… (2)
CaO + 2HF → CaF ₂ + H ₂ O …………………………………… (3)
CaCO _Three + 2HCl → CaCl ₂ + H ₂ O + CO ₂ ………………… (4)
CaCO _Three + 2HF → CaF ₂ + H ₂ O + CO ₂ ……………………… (5)
[0038]
First, chlorofluorocarbon R-12 is decomposed by the reaction shown in the formula (1), and strong acids of HCl and HF are generated, but the reaction of the formula (2) and (3) is caused by CaO in the reactor 33 almost simultaneously. To be summed. Therefore, the pipe line is not corroded by a strong acidic substance as in the prior art. Therefore, the lifetime of the decomposition treatment apparatus is long, and a large-capacity neutralization facility and a large amount of neutralizing agent are not required. In addition, the CaCO of formula (1) _Three Is obtained by the reaction of the equations (4) and (5). ₂ And CaF ₂ To change. All of the formulas (2) to (5) are neutralization reactions, but the reaction according to the formulas (2) and (3) is mainly used.
[0039]
As a result, Freon R-12 is
CCl ₂ F ₂ + 2CaO → CaCl ₂ + CaF ₂ + CO ₂ …………… (6)
Is broken down as a small amount

It is decomposed as.
[0040]
FIG. 4 is a graph showing the relationship between the decomposition rate and temperature at the time of decomposition of Freon R-12 with calcium oxide. As described in the figure, the flow rate of Freon is 2 kg / h, water is 20 g / min, and CaO is 2 kg. This is an example of reaction. According to FIG. 4, when the temperature in the reactor reaches 400 ° C., the decomposition rate becomes almost 100%. FIG. 5 is also a graph showing the relationship between the decomposition rate and time (minutes). When the temperatures were 400 ° C. and 300 ° C., the decomposition rate reached 100% in about 20 minutes at 400 ° C. It has been found.
[0041]
In the case of Freon R-22, the basic formula of the decomposition reaction is represented by the following formula (8) or (9).

[0042]
Actually, the reaction of the formula (8) occurs preferentially, and methane CH is contained in the gas after the reaction. _Four Many are included. The neutralization reaction of HCl and HF generated by the above reaction is performed almost simultaneously based on the above formulas (2) to (5). Further, when the internal temperature of the reactor 42 is 400 ° C. or higher, the following reactions (10) to (12) occur.

[0043]
However, methane CH in the gas after reaction _Four As a whole, it is considered that the reaction of the formulas (8) and (10) is mainly performed.
[0044]
FIG. 6 is a graph showing the relationship between decomposition rate and temperature at the time of decomposition of Freon R-22 with calcium oxide. As described in the figure, the flow rate of Freon is 2 kg / h, water is 20 g / min, and CaO is 2 kg. This is an example of reaction. According to FIG. 6, as in the case of Freon R-12, when the temperature in the reactor reaches 400 ° C., the decomposition rate becomes almost 100%. FIG. 7 is a graph showing the relationship between the decomposition rate and the reaction time (minutes). When the temperature is 400 ° C., the decomposition rate reaches 100% from the beginning. In addition, it was found that when the reaction was performed at a low temperature of about 300 ° C., the temperature gradually increased even when the power was turned off in the reaction time of 30 minutes, and the reaction time reached 500 ° C. in 100 minutes. This indicates that the decomposition reaction of calcium oxide and Freon R-22 is an exothermic reaction.
[0045]
The basic formula of the decomposition reaction in the case of Freon R-134a is represented by the following formulas (13) to (16).

[0046]
From the analysis of the product gas, many equations (14) and (15) are generated, and then (13) is generated. Equation (16) is rarely generated. Further, when the temperature in the reactor becomes higher than 300 ° C., the following reaction occurs slightly.

[0047]
FIG. 8 is a graph showing the relationship between decomposition rate and temperature at the time of decomposition of Freon R-134a with calcium oxide. As described in the figure, the flow rate of Freon is 2 kg / h, water is 20 g / min, and CaO is 2 kg. This is an example of reaction. According to FIG. 8, the decomposition rate becomes almost 100% when the temperature in the reactor reaches 400 ° C. as in the case of Freon R-12. FIG. 9 is a graph showing the relationship between the decomposition rate and the reaction time (minutes). When the temperature is 400 ° C., the decomposition rate reaches 100% from the beginning. In addition, it was found that when the reaction was performed at a low temperature of about 300 ° C., the temperature gradually increased even when the power was turned off in 60 minutes, and reached 500 ° C. in 100 minutes. This indicates that the decomposition reaction of calcium oxide and Freon R-134a is an exothermic reaction.
[0048]
The basic formula of the decomposition reaction in the case of Freon SF6 (sulfur hexafluoride) is represented by the following formulas (20) and (21). The Freon SF6 is an insulating gas and is usually enclosed in a high voltage power switch.
3CaO + SF ₆ + H ₂ O → 3CaH ₂ + H ₂ SO _Four ………………… (20)
SF ₆ + CaO + 3H ₂ O → CaSO _Four + 6HF …………………… (21)
[0049]
The above equation (20) is mainly used. H generated at this time ₂ SO _Four Is
CaO + H ₂ SO _Four → CaSO _Four + H ₂ O ……………………………… (22)
Neutralized by
[0050]
The above description is a reaction formula for chlorofluorocarbons, but other halides such as halon, trichloroethylene, and trichlorotan, and organic compounds having a benzene nucleus such as benzene and monochlorobenzene can be decomposed by the same reaction formula. .
[0051]
The following equation (23) is generated as a reaction not directly related to the decomposition reaction.
CaO + H ₂ O → Ca (OH) ₂ ……………………………………… (23)
This is an exothermic reaction in which calcium oxide reacts with water to produce calcium hydroxide, ₂ When water vapor is used as O, there is a case where a high temperature vapor is naturally obtained and a heat source is not required for decomposition by CaO. Further, by devising the heat dissipation mechanism of the reactor 33, heating by self-heating is possible after the initial heating, and the decomposition reaction proceeds spontaneously.
[0052]
In the present embodiment, water is added from the water tank 34 to the reactor 33, but water is not necessarily required for the reaction itself, and for example, the reaction described in the equation (6) proceeds. In this case, it is important to crush CaO finely to increase the contact area with chlorofluorocarbon, and since the reaction does not penetrate into the inside of CaO, the internal CaO is crushed after a certain time and unreacted CaO is removed from the surface. It is necessary to put out.
[0053]
When water is added to the reactor 33, the reaction with CaO penetrates to the inside, and the exothermic reaction according to the equation (23) proceeds. And it was confirmed that it continued until CaO disappeared. In this case, it is necessary to cool the outside of the reactor 33 with air or water.
[0054]
Next, reaction heat balance sheets for the reaction formulas (1) to (23) are shown in Tables 1 to 23. The table was obtained by simulation using a computer database.
[0055]
[Table 1]

[0056]
The following reaction formulas in Table 1 correspond to the reaction formula (1), and the reaction formulas in Tables 2 to 23 also correspond to the reaction formulas (2) to (23), respectively.

[0057]
In Tables 1 to 23, (g) indicates a gaseous state, (l) indicates a liquid state, and the others indicate a solid state. T in each table indicates a reaction temperature (° C.), an exothermic reaction when the sign of the calorific value in deltaH (kcal) is (−), and an endothermic reaction when (+). . deltaS (cal) indicates entropy, deltaG (kcal) indicates the direction of reaction with Gibbs free energy, and the sign (-) indicates that the reaction proceeds from left to right (→) as in the reaction equation. Yes. K is a ratio of the left amount and the right amount in the reaction formula, and 3.203E + 067 in Table 1 is 3.203 × 10 ⁶⁷ This indicates that the substance on the right side can be formed. The same applies to Tables 2 to 23 below.
[0058]
[Table 2]

[0059]
[Table 3]

[0060]
[Table 4]

[0061]
[Table 5]

[0062]
[Table 6]

[0063]
[Table 7]

[0064]
[Table 8]

[0065]
[Table 9]

[0066]
[Table 10]

[0067]
[Table 11]

[0068]
[Table 12]

[0069]
[Table 13]

[0070]
[Table 14]

[0071]
[Table 15]

[0072]
[Table 16]

[0073]
[Table 17]

[0074]
[Table 18]

[0075]
[Table 19]

[0076]
[Table 20]

[0077]
[Table 21]

[0078]
[Table 22]

[0079]
[Table 23]

[0080]
【The invention's effect】
As explained in detail above, according to the present invention, it is possible to decompose organic compounds having chlorofluorocarbons or benzene nuclei, and further difficult-to-decompose substances such as trichlorethylene, halon, SF6 and the like using calcium oxide. Since the neutralization reaction with CaO occurs almost simultaneously, corrosion of containers and piping due to strong acid generated in the decomposition process using other decomposition methods such as the plasma method or combustion method does not occur, and the life of the decomposition treatment equipment And a large capacity neutralization facility and a large amount of neutralizing agent are not required. In particular, since the reaction is an exothermic reaction, if only the initial heating is performed, the decomposition reaction will continue even if the heating source is shut off at the same time as the start of the reaction, which can also contribute to power saving.
[0081]
In particular, it is not necessary to maintain high-temperature and high-pressure conditions as in the case of hydrothermal reaction, design for withstanding mechanical strength is unnecessary, and materials to be used are not limited. The apparatus is simple in terms of mechanism, and there is no need to change the structure depending on the type of substance to be decomposed, and operational control is easy.
[0082]
Moreover, since it is not necessary to maintain the inside of a reactor at high temperature, energy cost can be reduced. In addition, there is no possibility that the container or the pipe line is corroded by the acidic substance. Further, it is possible to prevent a phenomenon in which the iron content contained in the container or the like is corroded by an acid and the durability is lowered.
[0083]
In the case of a conventionally known catalyst method, there is a problem that deterioration due to oxidation or the like of the catalyst occurs, whereas in the case of the present invention, since the catalyst is not used, there is no problem described above. Moreover, it can be applied not only to chlorofluorocarbons but also to other halides or organic substances having a benzene nucleus.
[0084]
Since calcium oxide itself is inexpensive and can also be used as a neutralizing agent, there is an advantage that the running cost is reduced. The acidic gas generated by the decomposition reaction is neutralized in the reactor almost simultaneously with the generation by calcium oxide and is not discharged outside the reactor, so that the pipeline is corroded by strong acidic substances as in the past. There is nothing to do. And the gas discharged from the reactor is CO ₂ , CH _Four , H ₂ , CO and the like are components, so that the decomposition treatment apparatus such as a pipe line is not corroded, and the combustible gas can be burned and discharged after cooling. Moreover, CaF which is the processed material after reaction produced | generated by reaction ₂ , CaCl ₂ , CaSO _Four And the like are solid, so that they can be easily taken out from the reactor and can be recycled. Furthermore, the configuration of the apparatus is relatively simple compared to conventional apparatuses, and the apparatus itself can be easily scaled up or down.
[0085]
Therefore, according to the present invention, a machine that can withstand high temperatures and pressures when decomposing refractory substances such as chlorofluorocarbons and organic compounds having benzene nuclei as environmental pollutants, and other halides such as trichlorethylene, halon, and SF6. A method and apparatus for decomposing a difficult-to-decompose substance that does not require high strength, prevents corrosion of pipes and discharge valves due to strong acids, and reduces material costs and running costs Can do.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a basic embodiment of the present invention.
FIG. 2 is a side sectional view of a reactor used in this embodiment.
FIG. 3 is a plan view of FIG. 2;
FIG. 4 is a graph showing the relationship between the decomposition rate and temperature at the time of decomposition of Freon R-12.
FIG. 5 is a graph showing the relationship between decomposition rate and time at the time of decomposition of Freon R-12.
FIG. 6 is a graph showing the relationship between the decomposition rate and temperature during decomposition of Freon R-22.
FIG. 7 is a graph showing the relationship between decomposition rate and time at the time of decomposition of Freon R-22.
FIG. 8 is a graph showing the relationship between decomposition rate and temperature at the time of decomposition of Freon R-134a.
FIG. 9 is a graph showing the relationship between the decomposition rate and time at the time of decomposition of Freon R-134a.
FIG. 10 is a system diagram showing a conventional apparatus for treating environmental pollutants by hydrothermal reaction treatment.
FIG. 11 is a system diagram showing an apparatus for treating environmental pollutants by another conventional hydrothermal reaction treatment.
[Explanation of symbols]
31 ... Decomposed material
32 ... Flow control valve
33 ... Reactor
34 ... Water tank
35 ... Water supply pump
36 ... Evaporator
37 ... Internal heater
39 ... (calcium oxide) inlet
40 ... calcium oxide
42 ... Cooler
43 ... Neutralizer
44 ... Combustion device
45 ... Discharge port
Reference number P2909

Claims (4)

The mixture of the material to be decomposed and the solvent is contacted with calcium oxide in the reactor, and the acidic substance produced by the reaction is neutralized and made harmless in the reactor almost simultaneously with the production, and then decomposed from the reactor. Reacted gas and liquid components that have been processed are taken out and sent to a cooler to cool the gas to be decomposed, and the cooled gas is neutralized by a neutralizer to make it harmless. Method for decomposing substances. 2. The method for decomposing a hardly decomposable substance according to claim 1 , wherein the combustible component is combusted by the combustor after the neutralization by the neutralizer.   A reactor in which calcium oxide is introduced, a reactor equipped with an inlet for the substance to be decomposed, a solvent inlet and an internal heater, a cooler for cooling the high-temperature gas of the substance to be decomposed, and a substance generated by the reaction The neutralization device neutralizes and detoxifies the substance to be decomposed and the calcium oxide in the presence of a solvent in a reactor while heating and reacting, and then the high-temperature gas of the object to be decomposed is cooled. An apparatus for decomposing a hardly decomposable substance, wherein the apparatus is cooled by a vessel and neutralizes a small amount of residual acidic substance by a neutralizing apparatus. The decomposition apparatus for a hardly decomposable substance according to claim 3 , wherein a combustion apparatus for performing a combustion process on combustible components after performing a neutralization process with a neutralizer is provided.

Images