JP2005066562A

JP2005066562A - Ceramic filter having organic chlorine compound decomposition function and method for purifying exhaust gas using the same

Info

Publication number: JP2005066562A
Application number: JP2003303810A
Authority: JP
Inventors: Shunji Inoue; 俊二井上
Original assignee: NGK Insulators Ltd
Current assignee: NGK Insulators Ltd
Priority date: 2003-08-28
Filing date: 2003-08-28
Publication date: 2005-03-17

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic filter having an organic chlorine compound decomposition function, which can remove also the organic chlorine compound together with a particulate radioactive material, and a method for purifying an exhaust gas using the same. <P>SOLUTION: An organic chlorine compound decomposition catalyst particle 2 is dispersed and carried on an inside of the porous ceramic filter of a cylinder type with a bottom, composed of a particle 1 of a quality of silicon carbide, alumina, or cordierite. The organic chlorine compound decomposition catalyst particle 2 is composed of a catalyst component 4 selected from the group consisting of Pt, Pd, Ru, Mn, Cr, V, W, and Mo, and a catalyst carrier particle 3 consisting of TiO<SB>2</SB>or Al<SB>2</SB>O<SB>3</SB>. An incinerator flue gas produced by an incineration of flammable radioactive waste in an incinerator, or a melting exhaust gas produced by the melting of inflammable radioactive waste in a melting furnace can be purified by a ceramic filter device in which the ceramic filter having the organic chlorine compound decomposition function is set. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、主として放射性廃棄物の焼却炉排ガスや溶融排ガスの処理の分野で用いられる、有機塩素化合物分解機能を有するセラミックフィルタ及びこれを用いた排ガス浄化方法に関するものである。 The present invention relates to a ceramic filter having a function of decomposing organochlorine compounds and a method for purifying exhaust gas using the same, which are mainly used in the field of incinerator exhaust gas and molten exhaust gas for radioactive waste.

従来から、原子力発電所や研究所などの放射性物質取り扱い施設において発生する放射性廃棄物のうち、可燃性放射性廃棄物は焼却炉で焼却され、また不燃性放射性廃棄物は溶融炉において溶融処理されている。その際に発生する焼却排ガスや溶融排ガスは、特許文献、特許文献２に示されるように、セラミックフィルタ装置に導かれて粒子状放射性物質が除去されている。 Conventionally, combustible radioactive waste is incinerated in an incinerator among radioactive waste generated in radioactive material handling facilities such as nuclear power plants and laboratories, and incombustible radioactive waste is melted in a melting furnace. Yes. Incinerated exhaust gas and molten exhaust gas generated at that time are guided to a ceramic filter device to remove particulate radioactive substances, as shown in Patent Documents and Patent Documents 2.

このためのセラミックフィルタには、耐熱性と強度に優れた炭化ケイ素質、アルミナ質、もしくはコージライト質からなる多孔質セラミックフィルタが用いられており、過去長年にわたり安定に使用されてきた運転実績がある。ところが近年、排ガス中のダイオキシンなどの有機塩素化合物に対する規制が強くなっており、放射性廃棄物中に塩化ビニルシートなどの塩素含有物質が混入している場合には、排ガス中に含まれる有機塩素化合物をも確実に除去することが求められている。 For this purpose, porous ceramic filters made of silicon carbide, alumina, or cordierite with excellent heat resistance and strength are used, and have been used stably over the past many years. is there. However, in recent years, regulations on organochlorine compounds such as dioxin in exhaust gas have become stronger, and when chlorine-containing substances such as vinyl chloride sheets are mixed in radioactive waste, organochlorine compounds contained in exhaust gas. Is also required to be reliably removed.

そこで、セラミックフィルタ装置の後段に有機塩素化合物分解触媒を充填した触媒反応塔などを設置することも検討されているが、既設の設備の場合にはその設置スペースを確保することが容易ではなく、また新設設備の場合にも設置コスト及びランニングコストがかかるという問題があった。
特公平５−５８１５８号公報特開２０００−３５４７１７号公報 Therefore, it is also considered to install a catalytic reaction tower packed with an organochlorine compound decomposition catalyst in the subsequent stage of the ceramic filter device, but in the case of existing equipment, it is not easy to secure the installation space, In addition, there is a problem that installation costs and running costs are required in the case of new facilities.
Japanese Patent Publication No. 5-58158 JP 2000-354717 A

本発明は上記した従来の問題点を解決し、有機塩素化合物分解装置を新たに設置することなく、粒子状放射性物質と同時に有機塩素化合物をも除去することができる有機塩素化合物分解機能を有するセラミックフィルタ及びこれを用いた排ガス浄化方法を提供するためになされたものである。 The present invention solves the above-mentioned conventional problems, and has a function of decomposing organochlorine compounds, which can remove organochlorine compounds at the same time as particulate radioactive substances, without newly installing an apparatus for decomposing organochlorine compounds. The present invention has been made to provide a filter and an exhaust gas purification method using the filter.

上記の課題を解決するためになされた請求項１に記載の本発明の有機塩素化合物分解機能を有するセラミックフィルタは、炭化ケイ素質、アルミナ質、もしくはコージライト質の粒子からなる多孔質で有底円筒状のセラミックフィルタであり、その内部に有機塩素化合物分解触媒粒子を分散担持させたことを特徴とするものである。このセラミックフィルタは、全長１〜２ｍ、外径５５〜６５ｍｍ、肉厚５〜１５ｍｍのサイズを有することが好ましく、その平均気孔径が２０〜５０μｍ、気孔率が２０〜４０％であることが好ましい。また曲げ強度が１０ＭＰａ以上であることが好ましい。 The ceramic filter having an organochlorine compound decomposition function of the present invention according to claim 1, which has been made to solve the above-mentioned problems, is porous and bottomed composed of silicon carbide, alumina, or cordierite particles. A cylindrical ceramic filter is characterized in that organochlorine compound decomposition catalyst particles are dispersed and supported therein. This ceramic filter preferably has a length of 1 to 2 m, an outer diameter of 55 to 65 mm, and a wall thickness of 5 to 15 mm, and preferably has an average pore diameter of 20 to 50 μm and a porosity of 20 to 40%. . The bending strength is preferably 10 MPa or more.

またこのセラミックフィルタは、フィルタ重量の１〜２０重量％の有機塩素化合物分解触媒粒子を担持させたものであることが好ましく、有機塩素化合物分解触媒粒子は、Ｐｔ，Ｐｄ，Ｒｕ，Ｍｎ，Ｃｒ，Ｖ，Ｗ、Ｍｏよりなる群から選択された触媒成分と、ＴｉＯ_２またはＡｌ_２Ｏ_３からなる触媒担体粒子とからなるものとすることが好ましい。またこの触媒担体粒子の５０％平均粒子径が、０.１〜１０μｍであることが好ましい。 The ceramic filter preferably supports 1 to 20% by weight of the organic chlorine compound decomposition catalyst particles based on the weight of the filter, and the organic chlorine compound decomposition catalyst particles include Pt, Pd, Ru, Mn, Cr, It is preferable that the catalyst component is selected from the group consisting of V, W, and Mo and catalyst carrier particles made of TiO ₂ or Al ₂ O ₃ . The 50% average particle diameter of the catalyst carrier particles is preferably 0.1 to 10 μm.

請求項８に記載の本発明の排ガス浄化方法は、可燃性放射性廃棄物を焼却炉で焼却し、その焼却排ガスを一次セラミックフィルタ装置で高温除塵したうえ、上記の有機塩素化合物分解機能を有するセラミックフィルタがセットされた二次セラミックフィルタ装置で浄化することを特徴とするものである。この場合、一次セラミックフィルタ装置の運転温度を７００〜９００℃、二次セラミックフィルタ装置の運転温度を２００〜５００℃とすることが好ましく、二次セラミックフィルタ装置のろ過速度を１〜３ｃｍ／秒とすることが好ましい。 The exhaust gas purification method of the present invention according to claim 8 is a ceramic having the above-mentioned organic chlorine compound decomposition function after incineration of combustible radioactive waste in an incinerator, dusting the incinerated exhaust gas at a high temperature with a primary ceramic filter device. Purification is performed by a secondary ceramic filter device in which a filter is set. In this case, the operating temperature of the primary ceramic filter device is preferably 700 to 900 ° C., the operating temperature of the secondary ceramic filter device is preferably 200 to 500 ° C., and the filtration rate of the secondary ceramic filter device is 1 to 3 cm / sec. It is preferable to do.

請求項１１に記載の本発明の排ガス浄化方法は、可燃性放射性廃棄物を焼却炉で焼却し、その焼却排ガス中の未燃分を二次燃焼室で燃焼したうえ、排ガスを空気混合、水噴霧、熱交換等により冷却し、上記の有機塩素化合物分解機能を有するセラミックフィルタがセットされたセラミックフィルタ装置で浄化することを特徴とするものである。この場合、二次燃焼室の運転温度を８００℃以上、セラミックフィルタ装置の運転温度を２００〜５００℃とすることが好ましく、セラミックフィルタ装置のろ過速度を１〜３ｃｍ／秒とすることが好ましい。 In the exhaust gas purification method of the present invention according to claim 11, combustible radioactive waste is incinerated in an incinerator, the unburned content in the incinerated exhaust gas is burned in the secondary combustion chamber, the exhaust gas is mixed with air, water It is cooled by spraying, heat exchange or the like, and purified by the ceramic filter device in which the ceramic filter having the above-mentioned organochlorine compound decomposition function is set. In this case, the operating temperature of the secondary combustion chamber is preferably 800 ° C. or higher, the operating temperature of the ceramic filter device is preferably 200 to 500 ° C., and the filtration rate of the ceramic filter device is preferably 1 to 3 cm / sec.

請求項１４に記載の本発明の排ガス浄化方法は、不燃性放射性廃棄物を溶融炉で溶融し、その溶融排ガスを上記の有機塩素化合物分解機能を有するセラミックフィルタがセットされたセラミックフィルタ装置で浄化することを特徴とするものである。この場合、セラミックフィルタ装置の運転温度を２００〜５００℃とすることが好ましく、セラミックフィルタ装置のろ過速度を１〜３ｃｍ／秒とすることが好ましい。セラミックフィルタ装置の運転温度は排ガスダストに亜鉛、鉛等の低融点物質が多量含まれている場合には、なかでも２００〜３００℃とすることが好ましい。 According to the exhaust gas purification method of the present invention as set forth in claim 14, the non-combustible radioactive waste is melted in a melting furnace, and the molten exhaust gas is purified by a ceramic filter device in which the ceramic filter having the organochlorine compound decomposition function is set. It is characterized by doing. In this case, the operating temperature of the ceramic filter device is preferably 200 to 500 ° C., and the filtration rate of the ceramic filter device is preferably 1 to 3 cm / second. When the exhaust gas dust contains a large amount of low melting point substances such as zinc and lead, the operating temperature of the ceramic filter device is preferably 200 to 300 ° C.

本発明の有機塩素化合物分解機能を有するセラミックフィルタは、耐熱性と強度に優れた炭化ケイ素質、アルミナ質、もしくはコージライト質の粒子からなる多孔質で有底円筒状のセラミックフィルタの内部に有機塩素化合物分解触媒粒子を分散担持させたものである。このため従来と同様に粒子状放射性物質を確実に除去することができるうえ、セラミックフィルタの内部でダイオキシンなどの有機塩素化合物を分解除去することができる。このため有機塩素化合物分解装置を新たに設置することなく、粒子状放射性物質と同時に有機塩素化合物をも除去することができる。 The ceramic filter having a function of decomposing an organic chlorine compound of the present invention is organic in a porous bottomed cylindrical ceramic filter made of silicon carbide, alumina, or cordierite particles having excellent heat resistance and strength. In this case, chlorine compound decomposition catalyst particles are dispersed and supported. For this reason, the particulate radioactive substance can be reliably removed as in the prior art, and an organic chlorine compound such as dioxin can be decomposed and removed inside the ceramic filter. Therefore, the organic chlorine compound can be removed simultaneously with the particulate radioactive material without installing a new organic chlorine compound decomposition apparatus.

また請求項８記載の本発明の排ガス浄化方法によれば、可燃性放射性廃棄物の焼却排ガスを一次セラミックフィルタ装置で高温除塵したうえ、上記のセラミックフィルタがセットされた二次セラミックフィルタ装置で更に除塵するので、従来と同様に粒子状放射性物質を確実に除去することができるうえ、セラミックフィルタの内部でダイオキシンなどの有機塩素化合物を分解除去することができる。焼却排ガス中には多量のダストが含まれるが、一次セラミックフィルタ装置で高温除塵されるので、二次セラミックフィルタ装置の有機塩素化合物分解機能が損なわれることはない。 According to the exhaust gas purification method of the present invention as set forth in claim 8, the incineration exhaust gas of the combustible radioactive waste is subjected to high temperature dust removal with the primary ceramic filter device, and further, with the secondary ceramic filter device in which the ceramic filter is set. Since dust is removed, the particulate radioactive material can be reliably removed as in the prior art, and organic chlorine compounds such as dioxin can be decomposed and removed inside the ceramic filter. Although a large amount of dust is contained in the incineration exhaust gas, since the high temperature dust is removed by the primary ceramic filter device, the organic chlorine compound decomposition function of the secondary ceramic filter device is not impaired.

また請求項１１記載の本発明の排ガス浄化方法によれば、可燃性放射性廃棄物を焼却炉で焼却し、その焼却排ガス中の未燃分を二次燃焼室で二次燃焼したうえ、上記のセラミックフィルタがセットされたセラミックフィルタ装置で浄化するので、二次燃焼ガス中に含まれる粒子状放射性物質を確実に除去することができるうえ、セラミックフィルタの内部でダイオキシンなどの有機塩素化合物を分解除去することができる。 According to the exhaust gas purification method of the present invention as set forth in claim 11, combustible radioactive waste is incinerated in an incinerator, the unburned content in the incinerated exhaust gas is subjected to secondary combustion in a secondary combustion chamber, and the above-mentioned Since it is purified by the ceramic filter device in which the ceramic filter is set, particulate radioactive materials contained in the secondary combustion gas can be removed reliably, and organic chlorine compounds such as dioxin are decomposed and removed inside the ceramic filter. can do.

更に請求項１４記載の本発明の排ガス浄化方法によれば、不燃性放射性廃棄物の溶融排ガスを上記のセラミックフィルタがセットされたセラミックフィルタ装置で浄化することにより、溶融排ガス中に含まれる粒子状放射性物質を確実に除去することができるうえ、セラミックフィルタの内部でダイオキシンなどの有機塩素化合物を分解除去することができる。溶融排ガス中に含まれるダストは焼却排ガスに比較して微量であるから、このように直接セラミックフィルタに通しても、有機塩素化合物分解機能が損なわれることはない。 Furthermore, according to the exhaust gas purification method of the present invention as set forth in claim 14, particulates contained in the molten exhaust gas are purified by purifying the molten exhaust gas of non-combustible radioactive waste with the ceramic filter device in which the ceramic filter is set. In addition to reliably removing radioactive materials, organic chlorine compounds such as dioxins can be decomposed and removed inside the ceramic filter. Since the dust contained in the molten exhaust gas is very small compared to the incineration exhaust gas, even if it passes through the ceramic filter directly in this way, the organic chlorine compound decomposition function is not impaired.

図１は、本発明の有機塩素化合物分解機能を有するセラミックフィルタの構成を概念的に示した図である。このセラミックフィルタは、前記した特許文献１、２にも示されるように、首部を支持板に支持させて用いられるキャンドル型と呼ばれる有底円筒状のものである。現在、各原子力発電所で使用されている排ガス浄化用のセラミックスフィルタと同じく、全長１〜２ｍ、外径５５〜６５ｍｍ、肉厚５〜１５ｍｍのサイズを有するものとする。特に肉厚を５〜１５ｍｍとすることは排ガス中に含まれる粒子状放射性物質を確実に除去するうえでも強度の点でも必要であり、肉厚が５ｍｍよりも薄いサイズは、粒子状放射性物質の捕捉性能の点でも、強度の点でも不適当である。しかし１５ｍｍを越えると圧損が過大となるので好ましくない。肉厚が５ｍｍよりもはるかに薄いハニカム構造体は、粒子状放射性物質の捕捉性能の点で不適当である。 FIG. 1 is a diagram conceptually showing the structure of a ceramic filter having an organochlorine compound decomposition function of the present invention. As shown in Patent Documents 1 and 2 described above, this ceramic filter has a bottomed cylindrical shape called a candle type that is used with a neck supported by a support plate. It is assumed that it has a length of 1 to 2 m, an outer diameter of 55 to 65 mm, and a wall thickness of 5 to 15 mm, similar to the exhaust gas purification ceramic filter currently used in each nuclear power plant. In particular, the thickness of 5 to 15 mm is necessary for the removal of particulate radioactive materials contained in the exhaust gas both in terms of strength and in terms of strength. Neither capture performance nor strength is appropriate. However, if it exceeds 15 mm, the pressure loss becomes excessive, which is not preferable. A honeycomb structure having a wall thickness much thinner than 5 mm is inappropriate in terms of trapping performance of particulate radioactive materials.

このセラミックフィルタは、炭化ケイ素質、アルミナ質、もしくはコージライト質の粒子１を焼結させた多孔質体である。これらの材質に限定したのは、強度、耐熱性、コストのバランスを考慮すると、これらの材質が実用的であるためである。 This ceramic filter is a porous body obtained by sintering particles 1 of silicon carbide, alumina, or cordierite. The reason for limiting to these materials is that these materials are practical considering the balance of strength, heat resistance, and cost.

本発明では図１に示されるように、これらの粒子１により形成される多孔質体内部に、有機塩素化合物分解触媒粒子２が分散担持されている。有機塩素化合物分解触媒粒子２は、ＴｉＯ_２またはＡｌ_２Ｏ_３からなる触媒担体粒子３の表面に、Ｐｔ，Ｐｄ，Ｒｕ，Ｍｎ，Ｃｒ，Ｖ，Ｗ、Ｍｏよりなる群から選択された触媒成分４を担持させたものである。これらの触媒担体粒子３は大きな表面積を持つので、触媒成分４が排ガスと接触する有効表面積を増加させるうえで効果的である。触媒担体粒子３をなくし、多孔質体内部に触媒成分４を直接分散させただけでは十分な触媒活性が得られない。 In the present invention, as shown in FIG. 1, organochlorine compound decomposition catalyst particles 2 are dispersed and supported inside a porous body formed by these particles 1. Organochlorine compound decomposition catalyst particles 2 are catalyst components selected from the group consisting of Pt, Pd, Ru, Mn, Cr, V, W, and Mo on the surface of catalyst carrier particles 3 made of TiO ₂ or Al ₂ O _3. 4 is carried. Since these catalyst support particles 3 have a large surface area, they are effective in increasing the effective surface area with which the catalyst component 4 comes into contact with the exhaust gas. If the catalyst carrier particles 3 are eliminated and the catalyst component 4 is directly dispersed inside the porous body, sufficient catalytic activity cannot be obtained.

触媒担体粒子３の５０％平均粒子径は、０.１〜１０μｍとすることが好ましい。この範囲よりも大径となると触媒担体粒子３をセラミックフィルタ内部に分散担時させにくく、この範囲よりも小径となると担時後のセラミックフィルタの圧損が大きくなるからである。 The 50% average particle size of the catalyst carrier particles 3 is preferably 0.1 to 10 μm. If the diameter is larger than this range, it is difficult to disperse the catalyst carrier particles 3 inside the ceramic filter. If the diameter is smaller than this range, the pressure loss of the ceramic filter after loading becomes large.

なお、触媒担体粒子３をＴｉＯ_２またはＡｌ_２Ｏ_３からなるものとしたのは、これらが排ガス中に含まれるＳＯ_Xに対する耐性に優れるためである。なかでも触媒担体粒子３としてＴｉＯ_２を用いることが特に好ましい。触媒成分４をＰｔ，Ｐｄ，Ｒｕ，Ｍｎ，Ｃｒ，Ｖ，Ｗ、Ｍｏよりなる群から選択したのは、実用的な有機塩素化合物分解機能を有するためである。なかでも触媒成分４として、Ｐｔ，Ｐｄ，Ｖ，Ｗを用いることが特に好ましい。有機塩素化合物分解触媒粒子２は、フィルタ重量の１〜２０重量％を担持させるものとする。１重量％未満では有機塩素化合物分解機能が不十分であり、２０重量％を越えて担持させるとフィルタ圧損が増加するので好ましくない。 The reason why the catalyst carrier particles 3 are made of TiO ₂ or Al ₂ O ₃ is that they have excellent resistance to SO _X contained in the exhaust gas. Among these, it is particularly preferable to use TiO ₂ as the catalyst support particles 3. The catalyst component 4 is selected from the group consisting of Pt, Pd, Ru, Mn, Cr, V, W, and Mo because it has a practical organochlorine compound decomposition function. Among these, it is particularly preferable to use Pt, Pd, V, and W as the catalyst component 4. The organochlorine compound decomposition catalyst particles 2 carry 1 to 20% by weight of the filter weight. If it is less than 1% by weight, the organochlorine compound decomposing function is insufficient, and if it exceeds 20% by weight, the filter pressure loss increases, such being undesirable.

このように有機塩素化合物分解触媒粒子２を分散担持させた本発明のセラミックフィルタは、平均気孔径が２０〜５０μｍ、気孔率が２０〜４０％とすることが好ましい。平均気孔径がこれより小さいと圧損が高くなり、逆にこれより大きいと粒子状放射性物質を確実に除去することができない。また気孔率が２０％未満であると圧損が高くなり、４０％を越えると強度が不十分となる。放射性排ガス除去の用途に用いるためには曲げ強度が１０ＭＰａ以上であることが要求されており、上記の数値範囲を満たすことにより１０ＭＰａ以上の強度を達成できる。 Thus, it is preferable that the ceramic filter of the present invention in which the organic chlorine compound decomposition catalyst particles 2 are dispersed and supported has an average pore diameter of 20 to 50 μm and a porosity of 20 to 40%. If the average pore diameter is smaller than this, the pressure loss becomes higher. Conversely, if the average pore diameter is larger than this, the particulate radioactive material cannot be reliably removed. Further, when the porosity is less than 20%, the pressure loss becomes high, and when it exceeds 40%, the strength becomes insufficient. In order to use it for the purpose of removing radioactive exhaust gas, the bending strength is required to be 10 MPa or more. By satisfying the above numerical range, the strength of 10 MPa or more can be achieved.

セラミックフィルタの内部に有機塩素化合物分解触媒粒子２を分散担持させるには、有機塩素化合物分解触媒粒子２をスラリーとしてその中に多孔質のセラミックフィルタを浸漬して含浸させ、乾燥させる方法を取ることができる。この工程を繰り返すことにより、担持量を変えることができる。後記する実施例に示すように、触媒の担持量を増加させると圧損も増加するので、触媒の担持による初期圧損の増加を担持前の１〜３倍の範囲にとどめることが好ましい。なお、スラリーを含浸させた後に焼成してもよいが、焼成せずにそのまま設置しても運転温度により焼成されるため、焼成は省くことができる。以下にこの有機塩素化合物分解機能を有するセラミックフィルタの具体的な使用方法を示す。 In order to disperse and support the organochlorine compound decomposition catalyst particles 2 in the ceramic filter, a method is adopted in which the organochlorine compound decomposition catalyst particles 2 are slurried and immersed in a porous ceramic filter and dried. Can do. By repeating this step, the loading amount can be changed. As shown in the examples to be described later, since the pressure loss increases when the amount of the catalyst supported is increased, it is preferable to limit the increase in the initial pressure loss due to the catalyst support to a range of 1 to 3 times that before the support. Although it may be fired after impregnating the slurry, firing can be omitted because it is fired at the operating temperature even if it is installed without firing. The concrete usage method of the ceramic filter which has this organochlorine compound decomposition | disassembly function is shown below.

図２は請求項８〜１０の発明の実施形態を示す図であり、１０は可燃性放射性廃棄物を焼却する焼却炉、１１はその焼却排ガスを高温除塵する一次セラミックフィルタ装置、１２はその後段に配置された二次セラミックフィルタ装置である。ここでは二次セラミックフィルタ装置１２には、上記した有機塩素化合物分解機能を有するキャンドル型のセラミックフィルタをセットして用いている。 FIG. 2 is a view showing an embodiment of the invention of claims 8 to 10, wherein 10 is an incinerator for incinerating combustible radioactive waste, 11 is a primary ceramic filter device for removing dust from the incineration exhaust gas at high temperature, and 12 is a subsequent stage. Is a secondary ceramic filter device. Here, in the secondary ceramic filter device 12, the above-mentioned candle type ceramic filter having an organic chlorine compound decomposition function is set and used.

紙、布、樹脂などの可燃性放射性廃棄物は焼却炉１０で焼却され、焼却灰は焼却炉１０の下部から灰ドラムボックス１３に排出される。数百℃の焼却排ガスは一次セラミックフィルタ装置１１に導かれて除塵されたうえ、有機塩素化合物分解機能を有する二次セラミックフィルタ装置１２に導かれる。焼却排ガスに含まれる粒子状放射性物質はこれらの一次、二次のセラミックフィルタにより確実に除去されるとともに、焼却排ガスに含まれるダイオキシン等の有機塩素化合物は二次セラミックフィルタ装置１２にセットされた本発明のセラミックフィルタを通過する際に有機塩素化合物分解触媒粒子２により分解除去される。その後、焼却排ガスは空気混合器１４により冷却されたうえで、ＨＥＰＡフィルタ１５を経て大気中に排出される。予め除塵された焼却排ガスが二次セラミックフィルタ装置１２に導かれるので、目詰まりによる触媒活性の低下が生じにくい。 Combustible radioactive waste such as paper, cloth, and resin is incinerated in the incinerator 10, and the incinerated ash is discharged from the lower part of the incinerator 10 to the ash drum box 13. The incineration exhaust gas at several hundred degrees Celsius is guided to the primary ceramic filter device 11 for dust removal and then guided to the secondary ceramic filter device 12 having an organochlorine compound decomposition function. Particulate radioactive material contained in the incineration exhaust gas is reliably removed by these primary and secondary ceramic filters, and organic chlorine compounds such as dioxin contained in the incineration exhaust gas are set in the secondary ceramic filter device 12 When passing through the ceramic filter of the invention, it is decomposed and removed by the organochlorine compound decomposition catalyst particles 2. Thereafter, the incineration exhaust gas is cooled by the air mixer 14 and then discharged to the atmosphere through the HEPA filter 15. Since the incineration exhaust gas that has been dust-removed in advance is guided to the secondary ceramic filter device 12, it is difficult for the catalyst activity to decrease due to clogging.

なお、一次セラミックフィルタ装置１１の運転温度を７００〜９００℃、二次セラミックフィルタ装置１２の運転温度を２００〜５００℃とすることが好ましい。二次セラミックフィルタ装置１２の運転温度が２００℃未満であると有機塩素化合物分解触媒の活性が低下し、逆に５００℃を超えるとセラミックフィルタにシンタリングが生じてやはり触媒活性が低下するためである。 In addition, it is preferable that the operating temperature of the primary ceramic filter device 11 is 700 to 900 ° C., and the operating temperature of the secondary ceramic filter device 12 is 200 to 500 ° C. If the operating temperature of the secondary ceramic filter device 12 is less than 200 ° C., the activity of the organochlorine compound decomposition catalyst is lowered, and conversely if it exceeds 500 ° C., sintering occurs in the ceramic filter and the catalyst activity is also lowered. is there.

また、二次セラミックフィルタ装置１２のろ過速度を、１〜３ｃｍ／秒とすることが好ましい。ろ過速度がこれより遅いと設備の大型化を招き、これより速いと焼却排ガスと有機塩素化合物分解触媒粒子２との接触反応時間が不足し、十分に有機塩素化合物を分解できなくなるためである。このように本発明によれば、従来から設置されている二次セラミックフィルタ装置１２として、有機塩素化合物分解機能を有するキャンドル型のセラミックフィルタを用いることによって、設備を新設することなく焼却排ガスに含まれるダイオキシン等の有機塩素化合物を分解除去することができる。なお、二次セラミックフィルタ装置１２の直前で燃焼排ガス中にアンモニアガスを注入することにより、有機塩素化合物とともの窒素酸化物を同時に分解除去することもできる。 Moreover, it is preferable that the filtration rate of the secondary ceramic filter apparatus 12 shall be 1-3 cm / sec. If the filtration rate is slower than this, the equipment will be enlarged, and if it is faster than this, the contact reaction time between the incineration exhaust gas and the organochlorine compound decomposition catalyst particles 2 will be insufficient, and the organochlorine compound cannot be sufficiently decomposed. As described above, according to the present invention, the conventionally used secondary ceramic filter device 12 includes a candle-type ceramic filter having an organochlorine compound decomposition function, so that it is included in the incineration exhaust gas without newly installing equipment. Organic chlorine compounds such as dioxins can be decomposed and removed. In addition, by injecting ammonia gas into the combustion exhaust gas immediately before the secondary ceramic filter device 12, the nitrogen oxide together with the organic chlorine compound can be decomposed and removed at the same time.

図３は請求項１１〜１３の発明の実施形態を示す図である。１０は可燃性放射性廃棄物を焼却する焼却炉、１６はその焼却排ガス中の未燃分を二次燃焼する二次燃焼室である。二次燃焼室１６から排出された二次燃焼ガスは本発明のセラミックフィルタがセットされたセラミックフィルタ装置１７で浄化される。図２の場合と同様に、この二次燃焼室１６の運転温度を８００℃以上、セラミックフィルタ装置１７の運転温度を２００〜５００℃とすることが好ましい。またセラミックフィルタ装置１７のろ過速度を、１〜３ｃｍ／秒とすることが好ましい。 FIG. 3 is a view showing an embodiment of the invention of claims 11-13. 10 is an incinerator for incinerating combustible radioactive waste, and 16 is a secondary combustion chamber for secondary combustion of unburned components in the incineration exhaust gas. The secondary combustion gas discharged from the secondary combustion chamber 16 is purified by the ceramic filter device 17 in which the ceramic filter of the present invention is set. As in the case of FIG. 2, the operating temperature of the secondary combustion chamber 16 is preferably 800 ° C. or higher, and the operating temperature of the ceramic filter device 17 is preferably 200 to 500 ° C. Moreover, it is preferable that the filtration rate of the ceramic filter device 17 be 1 to 3 cm / second.

図４は請求項１４〜１６の発明の実施形態を示す図である。２０は不燃性放射性廃棄物を溶融する溶融炉であり、ここではキャニスタ内で誘導加熱を行う高周波溶融炉が用いられている。その溶融排ガスは本発明の有機塩素化合物分解機能を有するセラミックフィルタがセットされたセラミックフィルタ装置１７で浄化される。 FIG. 4 is a view showing an embodiment of the inventions of claims 14-16. Reference numeral 20 denotes a melting furnace for melting incombustible radioactive waste. Here, a high-frequency melting furnace that performs induction heating in a canister is used. The molten exhaust gas is purified by the ceramic filter device 17 in which the ceramic filter having the organochlorine compound decomposition function of the present invention is set.

この場合にも、溶融排ガス中に含まれる粒子状放射性物質は確実に除去されるとともに、溶融排ガス中に含まれるダイオキシン等の有機塩素化合物は本発明のセラミックフィルタを通過する際に分解除去される。溶融排ガスのダスト濃度は焼却排ガスよりも低いので、このように直接除塵しても目詰まりによる触媒活性の低下は生じにくい。 Also in this case, the particulate radioactive material contained in the molten exhaust gas is surely removed, and the organic chlorine compound such as dioxin contained in the molten exhaust gas is decomposed and removed when passing through the ceramic filter of the present invention. . Since the dust concentration of the molten exhaust gas is lower than that of the incineration exhaust gas, even if the dust is directly removed in this way, the catalyst activity is hardly lowered due to clogging.

セラミックフィルタ装置１７の運転温度は、１５０〜３００℃とすることが好ましい。１５０℃未満では触媒活性が低下し、３００℃を超えると後段のＨＥＰＡフィルタ１５に悪影響を与えるためである。また前記したと同じ理由により、セラミックフィルタ装置１７のろ過速度を１〜３ｃｍ／秒とすることが好ましい。 The operating temperature of the ceramic filter device 17 is preferably 150 to 300 ° C. This is because if the temperature is lower than 150 ° C., the catalytic activity is lowered, and if it exceeds 300 ° C., the HEPA filter 15 in the subsequent stage is adversely affected. For the same reason as described above, it is preferable to set the filtration rate of the ceramic filter device 17 to 1 to 3 cm / second.

このように本発明によれば、従来から設置されているセラミックフィルタ装置１７に有機塩素化合物分解機能を有する本発明のセラミックフィルタを用いることによって、設備を新設することなく溶融排ガスに含まれるダイオキシン等の有機塩素化合物を分解除去することができる。 As described above, according to the present invention, by using the ceramic filter of the present invention having the function of decomposing organochlorine compounds in the ceramic filter device 17 that has been conventionally installed, dioxins and the like contained in the molten exhaust gas without newly installing equipment It is possible to decompose and remove organochlorine compounds.

ＴｉＯ_２粒子の表面にＶ_２Ｏ_５粒子を付着させたＶ_２Ｏ_５−ＴｉＯ_２触媒を平均粒径が５μｍになるまで粉砕し、水に分散させて約２ｗｔ％のスラリーとした。このスラリー中に炭化ケイ素質の粒子からなる有底円筒状の多孔質セラミックフィルタ（全長１.５ｍ、外径６０ｍｍ、肉厚１０ｍｍ、平均気孔径４０μｍ、気孔率３０％）を浸漬し、担持量の異なる３種類のセラミックフィルタを得た。 A V ₂ O ₅ —TiO ₂ catalyst having V ₂ O ₅ particles attached to the surface of TiO ₂ particles was pulverized until the average particle size became 5 μm, and dispersed in water to give a slurry of about 2 wt%. A bottomed cylindrical porous ceramic filter (total length 1.5 m, outer diameter 60 mm, wall thickness 10 mm, average pore diameter 40 μm, porosity 30%) made of silicon carbide particles is immersed in this slurry, and the amount supported Three types of ceramic filters with different values were obtained.

触媒担持量と初期圧損との関係は表１に示すとおりであり、触媒担持量が２ｗｔ％のときの圧損が従来品の約１.５倍であった。

The relationship between the catalyst loading and the initial pressure loss is as shown in Table 1. The pressure loss when the catalyst loading was 2 wt% was about 1.5 times that of the conventional product.

実施例１のサンプル２の触媒担持セラミックフィルタを用い、ダイオキシン類の除去性能を測定したところ、表２の結果が得られた。このように、十分なダイオキシン類低減効果が確認された。

When the removal performance of dioxins was measured using the catalyst-supporting ceramic filter of Sample 2 of Example 1, the results shown in Table 2 were obtained. Thus, a sufficient dioxin reduction effect was confirmed.

本発明の有機塩素化合物分解機能を有するセラミックフィルタの概念図である。It is a conceptual diagram of the ceramic filter which has the organochlorine compound decomposition | disassembly function of this invention. 請求項８の発明の排ガス浄化方法の工程説明図である。It is process explanatory drawing of the exhaust gas purification method of invention of Claim 8. 請求項１１の発明の排ガス浄化方法の工程説明図である。It is process explanatory drawing of the exhaust gas purification method of invention of Claim 11. 請求項１４の発明の排ガス浄化方法の工程説明図である。It is process explanatory drawing of the exhaust gas purification method of invention of Claim 14.

Explanation of symbols

１炭化ケイ素質、アルミナ質、もしくはコージライト質の粒子
２有機塩素化合物分解触媒粒子
３触媒担体粒子
４触媒成分
１０焼却炉
１１一次セラミックフィルタ装置
１２二次セラミックフィルタ装置
１３灰ドラムボックス
１４空気混合器
１５ＨＥＰＡフィルタ
１６二次燃焼室
１７セラミックフィルタ装置
２０溶融炉

DESCRIPTION OF SYMBOLS 1 Particles of silicon carbide, alumina or cordierite 2 Organochlorine compound decomposition catalyst particles 3 Catalyst support particles 4 Catalyst component 10 Incinerator 11 Primary ceramic filter device 12 Secondary ceramic filter device 13 Ash drum box 14 Air mixer 15 HEPA filter 16 Secondary combustion chamber 17 Ceramic filter device 20 Melting furnace

Claims

Organochlorine compound characterized in that it is a porous, bottomed cylindrical ceramic filter made of silicon carbide, alumina, or cordierite particles, in which organochlorine compound decomposition catalyst particles are dispersedly supported. Ceramic filter with decomposition function.

2. The ceramic filter having an organic chlorine compound decomposition function according to claim 1, wherein the ceramic filter has a length of 1 to 2 m, an outer diameter of 55 to 65 mm, and a thickness of 5 to 15 mm.

2. The ceramic filter having an organochlorine compound decomposition function according to claim 1, wherein the average pore diameter is 20 to 50 [mu] m and the porosity is 20 to 40%.

2. The ceramic filter having an organochlorine compound decomposition function according to claim 1, wherein the bending strength is 10 MPa or more.

2. The ceramic filter having an organic chlorine compound decomposition function according to claim 1, wherein 1 to 20% by weight of the filter weight of the organic chlorine compound decomposition catalyst particles is supported.

The organochlorine compound decomposition catalyst particles are composed of a catalyst component selected from the group consisting of Pt, Pd, Ru, Mn, Cr, V, W, and Mo, and catalyst carrier particles made of TiO ₂ or Al ₂ O _3. The ceramic filter having an organochlorine compound decomposition function according to claim 1.

The ceramic filter having an organochlorine compound decomposition function according to claim 6, wherein the 50% average particle diameter of the catalyst support particles is 0.1 to 10 µm.

The combustible radioactive waste is incinerated in an incinerator, and the incinerated exhaust gas is subjected to high-temperature dust removal with a primary ceramic filter device, and the ceramic filter having the organochlorine compound decomposition function according to any one of claims 1 to 7 is set. An exhaust gas purification method comprising: purifying with a next ceramic filter device.

The exhaust gas purification method according to claim 8, wherein the operating temperature of the primary ceramic filter device is 700 to 900 ° C, and the operating temperature of the secondary ceramic filter device is 200 to 500 ° C.

The exhaust gas purification method according to claim 8, wherein the filtration rate of the secondary ceramic filter device is 1 to 3 cm / sec.

A ceramic having a function of decomposing organochlorine compounds according to any one of claims 1 to 7, in which combustible radioactive waste is incinerated in an incinerator and unburned components in the incineration exhaust gas are secondarily burned in a secondary combustion chamber. An exhaust gas purification method, wherein purification is performed by a ceramic filter device in which a filter is set.

The exhaust gas purification method according to claim 11, wherein the operation temperature of the secondary combustion chamber is 800 ° C or higher, and the operation temperature of the ceramic filter device is 200 to 500 ° C.

The exhaust gas purification method according to claim 11, wherein the filtration rate of the ceramic filter device is 1 to 3 cm / sec.

A nonflammable radioactive waste is melted in a melting furnace, and the molten exhaust gas is purified by a ceramic filter device in which a ceramic filter having an organochlorine compound decomposition function according to any one of claims 1 to 7 is set. Exhaust gas purification method.

The exhaust gas purification method according to claim 14, wherein the operating temperature of the ceramic filter device is 200 to 500 ° C.

The exhaust gas purification method according to claim 14, wherein the filtration rate of the ceramic filter device is 1 to 3 cm / sec.