JP4630976B2 - Glass melting furnace - Google Patents

Glass melting furnace Download PDF

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JP4630976B2
JP4630976B2 JP2007226859A JP2007226859A JP4630976B2 JP 4630976 B2 JP4630976 B2 JP 4630976B2 JP 2007226859 A JP2007226859 A JP 2007226859A JP 2007226859 A JP2007226859 A JP 2007226859A JP 4630976 B2 JP4630976 B2 JP 4630976B2
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local heating
melting tank
melting furnace
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JP2009057253A (en
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孝治 藤原
盛弘 新原
正宏 小林
厚 青嶋
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独立行政法人 日本原子力研究開発機構
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Description

本発明は、放射性廃液をガラス固化処理するためのガラス溶融炉に関し、更に詳しく述べると、堆積箇所検知装置によって堆積物の有無と位置を特定し、特定された堆積箇所の近傍を局所加熱装置によって局所加熱することにより、堆積物を選択的に流下させて抜き出すことができるようにしたガラス溶融炉に関するものである。   The present invention relates to a glass melting furnace for vitrifying radioactive waste liquid. More specifically, the presence and position of deposits are identified by a deposition location detector, and the vicinity of the identified deposition location is identified by a local heating device. The present invention relates to a glass melting furnace in which deposits can be selectively flowed down and extracted by local heating.

再処理工場などの原子力施設から発生する放射性廃液は、濃縮処理した後、ガラス原料と共にガラス溶融炉に供給され、溶融処理しガラス固化処理される。ガラス溶融炉としては、通常、溶融槽の側壁に対向するように主電極を設置し、ガラスに直接通電することにより生じるジュール熱を利用してガラスを加熱溶融する（直接通電方式）。この種のガラス溶融炉は従来公知であり、その詳細な構造については、例えば特許文献１などに記載されている。溶融したガラスは、溶融槽底部に設けられている流下ノズルから重力により抜き出されガラス固化体容器へ注入される。得られたガラス固化体は放射性廃棄物保管施設で保管される。   A radioactive liquid waste generated from a nuclear facility such as a reprocessing plant is concentrated, supplied to a glass melting furnace together with a glass raw material, melted and vitrified. As a glass melting furnace, a main electrode is usually installed so as to face the side wall of the melting tank, and glass is heated and melted by using Joule heat generated by directly energizing the glass (direct energization method). This type of glass melting furnace is conventionally known, and its detailed structure is described in, for example, Patent Document 1. The molten glass is extracted by gravity from a falling nozzle provided at the bottom of the melting tank and injected into a glass solidified container. The obtained vitrified body is stored in a radioactive waste storage facility.

ところで、再処理工場などから発生する高放射性廃液中には、ガラスへの溶解度の低い金属（クロム、ルテニウム、パラジウムなど）が含まれており、それらは溶解度を超えると酸化物等として析出する。ガラスよりも比重が大きいこれらの析出物の一部は、溶融槽底部へ沈降し、流下ノズルから排出されずに底部に徐々に蓄積されていく。析出物濃度が高くなったガラスは、通常の溶融したガラスに比べて電気抵抗が小さく、粘度が大きい。このため、ガラスを溶融する電流がこの堆積物に集中するため電流分布が偏り、ガラスが加熱され難くなる。また、堆積物は流下ノズルを閉塞させたり、流下ノズルに流入するガラスの流路を妨げ、流下ノズルからガラスを抜き出し難くするなどの支障が生じる。   By the way, the highly radioactive waste liquid generated from a reprocessing plant or the like contains metals (chromium, ruthenium, palladium, etc.) having low solubility in glass, and when they exceed the solubility, they precipitate as oxides. Some of these precipitates having a specific gravity greater than that of glass settle to the bottom of the melting tank and are gradually accumulated at the bottom without being discharged from the falling nozzle. Glass with a high precipitate concentration has a lower electrical resistance and a higher viscosity than ordinary molten glass. For this reason, since the current for melting the glass is concentrated on the deposit, the current distribution is biased and the glass is hardly heated. In addition, the deposits obstruct the flow nozzle, obstruct the glass flow path flowing into the flow nozzle, and make it difficult to extract the glass from the flow nozzle.

このような事態の発生を防止するため、従来方法では、析出物濃度が高くなり堆積が予測された場合に、ガラス原料及び放射性廃液の供給を停止し、溶融槽内のガラスを全て排出した後、ガラス溶融炉を降温し、残留した堆積物を物理的あるいは化学的な手法で除去する等の処置が必要であった。このように、堆積物を除去した後、ガラス溶融炉の運転を再開する。従って、ガラス溶融炉の運転を中断することになり、運転効率が低くなるばかりでなく、煩瑣な堆積物除去操作が必要になるし、炉メンテナンスに要するコストが多くかかるなどの問題がある。
実公平３−４８１８３号公報 In order to prevent the occurrence of such a situation, in the conventional method, when the deposit concentration is high and deposition is predicted, the supply of the glass raw material and radioactive waste liquid is stopped, and all the glass in the melting tank is discharged. It was necessary to take measures such as lowering the temperature of the glass melting furnace and removing the remaining deposits by physical or chemical methods. Thus, after removing deposits, the operation of the glass melting furnace is resumed. Therefore, the operation of the glass melting furnace is interrupted, and not only the operation efficiency is lowered, but also a troublesome sediment removal operation is required, and the cost required for the furnace maintenance is increased.
Japanese Utility Model Publication No. 3-48183

本発明が解決しようとする課題は、ガラス溶融炉運転中に、その溶融槽の底部近傍での堆積物の有無及び位置を特定し、その堆積箇所近傍を局所的に加熱できるようにして、堆積物の粘度を下げ、選択的に堆積物を抜き出すことができ、ガラス溶融炉を効率よく連続運転できるようにすることである。   The problem to be solved by the present invention is to determine the presence and position of deposits in the vicinity of the bottom of the melting tank during operation of the glass melting furnace so that the vicinity of the deposit can be heated locally. The object is to reduce the viscosity of the product, to selectively extract deposits, and to allow the glass melting furnace to operate efficiently and continuously.

ガラス溶融炉による放射性廃液の溶融固化処理において、運転開始と共に析出するクロム、ルテニウム、パラジウム等の金属酸化物は、比重が大きいため徐々に沈降し、溶融槽の底部に蓄積されていく。これらの堆積物は、電気抵抗が低く、温度が上昇に従って粘度は低下する。本発明は、このような物性に着目し、堆積物の有無及び位置を特定し、その堆積箇所の近傍を局所加熱するすることにより堆積物の粘度を下げ、選択的に抜き出すことができるようにしたものである。   In the melting and solidifying treatment of radioactive liquid waste in a glass melting furnace, metal oxides such as chromium, ruthenium, and palladium that are deposited with the start of operation gradually settle and accumulate at the bottom of the melting tank due to their large specific gravity. These deposits have a low electrical resistance and the viscosity decreases with increasing temperature. The present invention pays attention to such physical properties, specifies the presence and position of the deposit, and locally heats the vicinity of the deposit so that the viscosity of the deposit can be lowered and selectively extracted. It is a thing.

本発明は、底部が流下ノズルに向かって下向きに傾斜する構造の溶融槽と、該溶融槽の側壁に配設された複数の主電極を具備し、前記溶融槽内に投入したガラス原料と放射性廃液に前記主電極により直接通電し発生するジュール熱により加熱溶融し、溶融ガラスを流下ノズルから抜き出すようにしたガラス溶融炉において、前記溶融槽の底部近傍に、堆積物の有無及び位置を特定する堆積箇所検知装置と、該堆積箇所検知装置によって特定された堆積箇所の近傍を加熱する局所加熱装置とを設置し、局所加熱により堆積物の粘度を低下させることで堆積物の選択的な流下による抜き出しを可能にしたことを特徴とするガラス溶融炉である。   The present invention includes a melting tank having a structure in which a bottom portion is inclined downward toward a flow nozzle, and a plurality of main electrodes disposed on a side wall of the melting tank, and the glass raw material charged into the melting tank and radioactive In a glass melting furnace in which waste liquid is heated and melted by Joule heat generated by energizing directly with the main electrode and the molten glass is extracted from the flow nozzle, the presence and position of deposits are specified in the vicinity of the bottom of the melting tank. By installing a deposition location detection device and a local heating device that heats the vicinity of the deposition location identified by the deposition location detection device, and by reducing the viscosity of the deposition by local heating, the selective flow of the deposition It is a glass melting furnace characterized by enabling extraction.

例えば、溶融槽の底部に複数の底部電極が分散埋設されており、堆積箇所検知装置は前記底部電極間での抵抗計測方式で堆積物を検知し、局所加熱装置は前記底部電極間での直接通電方式で局所加熱を行うように構成する。あるいは、溶融槽の底部に複数の底部電極が分散埋設されていると共に溶融槽の底部近傍に達するように棒状電極が挿入可能となっており、堆積箇所検知装置は前記底部電極と棒状電極間での抵抗計測方式で堆積物を検知し、局所加熱装置は前記底部電極と棒状電極間での直接通電方式で局所加熱を行うように構成してもよい。   For example, a plurality of bottom electrodes are dispersedly embedded at the bottom of the melting tank, the deposition point detection device detects deposits by a resistance measurement method between the bottom electrodes, and the local heating device directly connects between the bottom electrodes. It is configured to perform local heating by an energization method. Alternatively, a plurality of bottom electrodes are dispersedly embedded at the bottom of the melting tank, and a rod-shaped electrode can be inserted so as to reach the vicinity of the bottom of the melting tank, and the deposition point detection device is interposed between the bottom electrode and the rod-shaped electrode. The deposit may be detected by the resistance measurement method, and the local heating device may be configured to perform the local heating by the direct current method between the bottom electrode and the rod-shaped electrode.

堆積箇所検知装置は、溶融槽の底部近傍に達するように挿入可能なプローブとし、接触検出方式で堆積物を検知するような構成も可能である。また局所加熱装置は、溶融槽の底部に分散埋設されている複数の発熱抵抗体からなり、該発熱抵抗体への通電発熱により局所加熱する構成も可能である。   The deposition location detection device may be a probe that can be inserted so as to reach the vicinity of the bottom of the melting tank, and may be configured to detect deposits by a contact detection method. In addition, the local heating device can be configured to include a plurality of heat generating resistors dispersedly embedded in the bottom of the melting tank, and to perform local heating by energization heat generation to the heat generating resistors.

また本発明は、これらのガラス溶融炉を使用し、主電極によるガラス溶融運転を継続しつつ、特定された堆積位置を局所加熱することにより、堆積物を選択的に流下させて抜き出すように運転するガラス溶融炉の運転方法である。   In addition, the present invention uses these glass melting furnaces, and continues the glass melting operation by the main electrode, while locally heating the specified deposition position, so that the deposit is selectively flowed down and extracted. This is a method of operating a glass melting furnace.

本発明に係るガラス溶融炉は、溶融槽の底部近傍に、堆積物の有無及び位置を特定する堆積箇所検知装置と、それによって特定された堆積位置の近傍を加熱する局所加熱装置とを設置する構成したことにより、ガラス溶融炉運転中に、堆積物の有無と位置を特定し、その堆積位置近傍を局所的に加熱することで、堆積物の粘度を下げ、選択的に堆積物を流下させ抜き出すことができる。そのため、ガラス溶融炉の運転を中断することなく効率よく連続的に行うことが可能となり、運転コストの低減を図ることができる。   In the glass melting furnace according to the present invention, a deposition location detection device that identifies the presence and position of deposits and a local heating device that heats the vicinity of the deposition location identified thereby are installed near the bottom of the melting tank. By configuring, during the glass melting furnace operation, the presence and location of deposits are specified, and the vicinity of the deposit position is locally heated, thereby lowering the viscosity of the deposit and selectively flowing down the deposit. Can be extracted. Therefore, it becomes possible to carry out efficiently and continuously without interrupting the operation of the glass melting furnace, and the operation cost can be reduced.

ここで、溶融槽の底部に複数の底部電極を分散埋設し、堆積箇所検知装置は前記底部電極間での抵抗計測方式、局所加熱装置は前記底部電極間での直接通電方式とすると、埋設した底部電極を両方の装置で共用できる。複数の底部電極と棒状電極を使用し、堆積箇所検知装置は前記底部電極と棒状電極間での抵抗計測方式、局所加熱装置は前記底部電極と棒状電極間での直接通電方式としても、両方の装置で電極を共用できる。   Here, a plurality of bottom electrodes are dispersedly embedded at the bottom of the melting tank, the deposition spot detection device is embedded in the resistance measurement method between the bottom electrodes, and the local heating device is directly energized between the bottom electrodes. The bottom electrode can be shared by both devices. A plurality of bottom electrodes and rod-shaped electrodes are used, the deposition point detection device is a resistance measurement method between the bottom electrode and the rod-shaped electrode, and the local heating device is a direct current method between the bottom electrode and the rod-shaped electrode. The electrode can be shared by the device.

図１は、本発明に係るガラス溶融炉の一実施例を示す説明図である。Ａは全体構成を示しており、Ｂは堆積箇所検知装置、Ｃは局所加熱装置を、それぞれ示している。このガラス溶融炉１０は、底部が流下ノズル１２に向かって下向きに傾斜する形状で耐食・耐火構造の溶融槽１４と、該溶融槽１４の側壁に対向配設された複数の主電極１６とを具備している。高放射性廃液はガラス供給系１８に送られ、予めガラス原料２０に染みこませた状態で、溶融槽１４内に供給する。溶融槽１４内に投入したガラス原料と高放射性廃液を、前記主電極１６により直接通電し、発生するジュール熱を利用して加熱溶融し、溶融ガラス２２を流下ノズル１２から流下させて抜き出す。その際に発生するガスはオフガス処理系２４を経て排出される。   FIG. 1 is an explanatory view showing an embodiment of a glass melting furnace according to the present invention. A shows the entire configuration, B shows a deposition site detection device, and C shows a local heating device. The glass melting furnace 10 includes a melting tank 14 having a corrosion-resistant and fire-resistant structure with a bottom inclined downward toward the flow-down nozzle 12, and a plurality of main electrodes 16 arranged to face the side walls of the melting tank 14. It has. The highly radioactive waste liquid is sent to the glass supply system 18 and supplied into the melting tank 14 in a state where the glass raw material 20 is preliminarily soaked. The glass raw material and the highly radioactive liquid waste introduced into the melting tank 14 are directly energized by the main electrode 16 and heated and melted using the generated Joule heat, and the molten glass 22 is flowed down from the flow-down nozzle 12 and extracted. The gas generated at that time is discharged through the off-gas treatment system 24.

前述したように、高放射性廃液中には、クロム、ルテニウム、パラジウム等のガラスへの溶解度の低い金属が含まれており、溶解度を超えると酸化物等として析出する。これらの析出物２６の一部は溶融ガラス２２よりも比重が大きい。従って、ガラス溶融炉１０では、運転開始と共に溶融槽１４中にクロム、ルテニウム、パラジウム等の金属酸化物が析出し、時間の経過につれて溶融槽１４の底部へ沈降する。それらは流下ノズル１２から排出されず、徐々に蓄積されていき堆積物２８となる。ところで、溶融ガラス２２は析出物の濃度に応じて電気抵抗が変化することから、運転中、逐次、溶融ガラス２２の電気抵抗を計測することで堆積状況を予測することができ、これにより、溶融炉内の析出物堆積状況を監視することができる。析出物濃度が高くなったガラスは、通常の溶融したガラスに比べ、電気抵抗が小さくなり、粘度が大きくなる。このため、ガラスを溶融する電流は、この堆積物に集中して電流分布が偏り、ガラスが加熱され難くなる。これらの堆積物２８は、温度の上昇に従って粘度が下がる性質を有するので、堆積物の周辺を加熱すると粘度が下がり、堆積物を選択的に流下させることができる。   As described above, the highly radioactive waste liquid contains a metal having low solubility in glass such as chromium, ruthenium, and palladium, and precipitates as an oxide or the like when the solubility is exceeded. Some of these precipitates 26 have a higher specific gravity than the molten glass 22. Therefore, in the glass melting furnace 10, metal oxides such as chromium, ruthenium, and palladium are deposited in the melting tank 14 at the start of operation, and settle to the bottom of the melting tank 14 as time passes. They are not discharged from the flow-down nozzle 12 but gradually accumulate and become deposits 28. By the way, since the electrical resistance of the molten glass 22 changes depending on the concentration of precipitates, the deposition state can be predicted by measuring the electrical resistance of the molten glass 22 sequentially during operation. The deposit accumulation status in the furnace can be monitored. Glass with a high precipitate concentration has a lower electrical resistance and a higher viscosity than ordinary molten glass. For this reason, the current that melts the glass is concentrated on the deposit, the current distribution is biased, and the glass is hardly heated. Since these deposits 28 have a property that the viscosity decreases as the temperature increases, the viscosity decreases when the periphery of the deposits is heated, and the deposits can be selectively flowed down.

そこで本発明では、溶融槽１４の底部近傍に、堆積物の有無と位置を特定する堆積箇所検知装置と、それによって特定された堆積位置の近傍を加熱する局所加熱装置とを設置する。この実施例は、溶融槽１４の底部に分散埋設した複数の底部電極３０を用いるものであり、謂わば「底部固定式」である。堆積箇所検知装置は、図１のＢに示すように、隣接する任意の底部電極３０間の電気抵抗を抵抗計３２で計測する抵抗計測方式であり、局所加熱装置は、図１のＣに示すように、前記底部電極３０間に電源３４から通電し加熱する直接通電方式としている。底部電極３０を変えて隣接する底部電極３０間で電気抵抗を計測することで、抵抗値が低い部位の分布から堆積物２８の有無と位置を特定することができる。従って、その位置に該当する底部電極３０間を選んで通電することにより、発生するジュール熱を利用して堆積物２８を局所加熱し、粘度を低下させて流動性を上げ、流下させることができる。なお、この実施例では、複数の底部電極３０は、堆積箇所検知装置と局所加熱装置とで共用できることになり、構成が簡略化される利点がある。局所加熱装置による局所加熱により、堆積物の粘度が低下し、それによって堆積物２８の選択的な抜き出しが実現できる。その結果、ガラス中の析出物濃度の上昇が抑えられ、ガラスは加熱され易くなる。   Therefore, in the present invention, a deposition location detection device that identifies the presence and position of deposits and a local heating device that heats the vicinity of the deposition location identified thereby are installed near the bottom of the melting tank 14. In this embodiment, a plurality of bottom electrodes 30 dispersedly embedded in the bottom of the melting tank 14 are used, which is a so-called “bottom fixed type”. As shown in FIG. 1B, the deposition location detection device is a resistance measurement method in which the electrical resistance between any adjacent bottom electrodes 30 is measured by an ohmmeter 32, and the local heating device is shown in FIG. 1C. As described above, a direct energization method is employed in which electricity is supplied from the power source 34 between the bottom electrodes 30 and heated. By measuring the electrical resistance between the adjacent bottom electrodes 30 by changing the bottom electrode 30, the presence and position of the deposit 28 can be specified from the distribution of the parts having low resistance values. Therefore, by electrifying between the bottom electrodes 30 corresponding to the position, the deposit 28 can be locally heated using the generated Joule heat, the viscosity can be lowered, the fluidity can be increased, and the flow can be lowered. . In this embodiment, the plurality of bottom electrodes 30 can be shared by the deposition point detection device and the local heating device, and there is an advantage that the configuration is simplified. Due to the local heating by the local heating device, the viscosity of the deposit is lowered, whereby the deposit 28 can be selectively extracted. As a result, an increase in the concentration of precipitates in the glass is suppressed, and the glass is easily heated.

図２は、本発明に係るガラス溶融炉の他の実施例を示す説明図である。ここでも、Ａは全体構成を示しており、Ｂは堆積箇所検知装置、Ｃは局所加熱装置を、それぞれ示している。ガラス溶融炉本体の構成は、図１に示すものと基本的に同様であってよいので、対応する部分に同一符号を付し、それらについての説明は省略する。   FIG. 2 is an explanatory view showing another embodiment of the glass melting furnace according to the present invention. Here too, A shows the overall configuration, B shows the deposition site detection device, and C shows the local heating device. Since the structure of the glass melting furnace main body may be basically the same as that shown in FIG. 1, the same reference numerals are given to corresponding parts, and description thereof will be omitted.

この実施例は、溶融槽１４の底部に分散埋設されている複数の底部電極３０と、溶融槽１４の底部近傍に達するように上方から挿入した棒状電極３６を用いるものであり、謂わば「プローブ式」である。堆積箇所検知装置は、図２のＢに示すように、前記底部電極３０と棒状電極３６間の電気抵抗を抵抗計３２で計測する抵抗計測方式であり、局所加熱装置は、図２のＣに示すように、前記底部電極３０と棒状電極３６間に電源３４で通電し加熱する直接通電方式としている。従って、この実施例でも、複数の底部電極３０及び棒状電極３６は、堆積箇所検知装置と局所加熱装置とで共用できることになり、構成は簡略化される。局所加熱装置による局所加熱により、堆積物２８の粘度を低下させて流動化し、それによって堆積物２８の選択的な抜き出しを実現する。   In this embodiment, a plurality of bottom electrodes 30 distributed and embedded at the bottom of the melting tank 14 and a rod-shaped electrode 36 inserted from above so as to reach the vicinity of the bottom of the melting tank 14 are used. Formula ". As shown in FIG. 2B, the deposition location detection device is a resistance measurement method in which the electrical resistance between the bottom electrode 30 and the rod-shaped electrode 36 is measured with an ohmmeter 32, and the local heating device is shown in FIG. As shown in the figure, a direct energization method is employed in which a power source 34 energizes and heats between the bottom electrode 30 and the rod electrode 36. Therefore, also in this embodiment, the plurality of bottom electrodes 30 and the rod-shaped electrodes 36 can be shared by the deposition site detection device and the local heating device, and the configuration is simplified. By the local heating by the local heating device, the viscosity of the deposit 28 is lowered and fluidized, thereby realizing the selective extraction of the deposit 28.

本発明において、堆積箇所検知装置は、上記実施例のような構成のみに限定されるものではない。図３は、接触式のプローブ４０を用いる例を示している。プローブ４０に振動・衝撃センサを取り付けて溶融槽１４の上方から挿入し、プローブ４０の先端が溶融槽１４の傾斜した底面に対して僅かな間隔をおいた状態を保ちつつ底面に沿って動かすことで堆積物の有無と位置を特定することができる。堆積物が存在すれば、プローブの先端が接触し、その時の振動・衝撃で検知できるからである。   In the present invention, the deposition site detection device is not limited to the configuration as in the above embodiment. FIG. 3 shows an example in which a contact probe 40 is used. A vibration / impact sensor is attached to the probe 40 and inserted from above the melting tank 14, and the tip of the probe 40 is moved along the bottom surface while maintaining a slight distance from the inclined bottom surface of the melting tank 14. To identify the presence and location of deposits. This is because if there is a deposit, the tip of the probe contacts and can be detected by vibration / impact at that time.

本発明において、局所加熱装置も、前記実施例のような構成のみに限定されるものではない。図４は底部固定式の例を、図５はプローブ式の例を、それぞれ示している。   In the present invention, the local heating device is not limited to the configuration as in the above embodiment. FIG. 4 shows an example of the bottom fixed type, and FIG. 5 shows an example of the probe type.

図４の底部固定式の場合、Ａに示すような発熱抵抗体方式、あるいはＢに示すような誘導加熱方式などがある。発熱抵抗体方式では、溶融槽１４の底部に発熱抵抗体４２を分散配設し、該発熱抵抗体４２に通電することで発熱させ、堆積物２８の粘度を低下させる。誘導加熱方式では、溶融槽１４の底部にコイル４４を分散配設し、該コイル４４に高周波電流を供給することで堆積物２８を局所発熱させる。これらの場合、発熱抵抗体４２やコイル４４の近くに別途電極を配設し、それらの電極を利用して堆積箇所検知装置を構成することができる。勿論、接触式のプローブを用いる方式でもよい。   In the case of the bottom fixed type in FIG. 4, there is a heating resistor type as shown in A, an induction heating type as shown in B, or the like. In the heating resistor system, the heating resistors 42 are dispersedly arranged at the bottom of the melting tank 14, and the heating resistors 42 are energized to generate heat, thereby reducing the viscosity of the deposit 28. In the induction heating method, the coils 44 are dispersedly arranged at the bottom of the melting tank 14, and a high frequency current is supplied to the coils 44 to cause the deposit 28 to generate heat locally. In these cases, a separate electrode can be disposed near the heating resistor 42 and the coil 44, and the deposition site detection device can be configured using these electrodes. Of course, a system using a contact type probe may be used.

図５のプローブ式の場合も、Ａに示すような発熱抵抗体方式、あるいはＢに示すような誘導加熱方式などがある。発熱抵抗体方式では、プローブ４６の先端に発熱抵抗体４８を組み込み、該発熱抵抗体４８に通電することで局所発熱させ、堆積物２８の粘度を低下させる。誘導加熱方式では、プローブ５０の先端にコイル５２を組み込み、該コイル５２に高周波電流を供給することで堆積物２８を局所発熱させる。これらの場合、溶融槽１４の底部に複数の電極３０を分散配設し、それらの電極３０を利用して堆積箇所検知装置を構成することができる。勿論、接触式のプローブを用いる方式でもよい。   Also in the case of the probe type of FIG. 5, there are a heating resistor type as shown in A, an induction heating type as shown in B, and the like. In the heating resistor method, a heating resistor 48 is incorporated at the tip of the probe 46, and the heating resistor 48 is energized to generate local heat, thereby reducing the viscosity of the deposit 28. In the induction heating method, a coil 52 is incorporated at the tip of the probe 50 and a high frequency current is supplied to the coil 52 to cause the deposit 28 to generate heat locally. In these cases, a plurality of electrodes 30 can be dispersedly arranged at the bottom of the melting tank 14, and the deposition site detection device can be configured using these electrodes 30. Of course, a system using a contact type probe may be used.

本発明に係るガラス溶融炉を用いて放射性廃液を処理する溶融炉運転方法の一例を図６に示す。この運転方法の特徴は、堆積物除去のために溶融炉の運転を中断する必要がない点である。運転手順は、例えば次のようになる。
（ａ）溶融槽にガラス原料と放射性廃液を投入する（運転期間を通じて投入し続ける）。
（ｂ）主電極への通電によりガラスを加熱溶融する。
（ｃ）ガラス中の析出物の濃度に応じて電気抵抗が変化するため、抵抗計測により堆積を予測することができる。また、通電加熱に平行して堆積箇所検知装置により堆積物検知を行う。なお、予め溶融炉の運転開始初期に溶融槽内に堆積物がないことを利用して、堆積箇所検知装置を校正しておく。
（ｄ）溶融槽内のガラス保持量が規定値に達するまで、上記（ａ）〜（ｃ）を繰り返す。
（ｅ）溶融槽内のガラス保持量が規定値に達したならば、溶融ガラスの流下のために流下ノズルの加熱を開始する。
（ｆ）前記（ｃ）の工程で堆積物が検知された場合には、流下ノズル加熱と同時に、堆積位置の近傍で局所加熱を行う。堆積物は加熱とともに粘度が低下し、選択的に流下させることができる。局所加熱装置は、堆積物を流下できるように加熱出力の調整を行いながら流下ノズルから堆積物を流下させる。
（ｇ）溶融ガラスの流下量が規定値に達するまで流下ノズルの加熱を続け、溶融ガラスの流下を継続する。
（ｈ）溶融ガラスの流下量が規定値に達したならば、流下ノズルの加熱を停止して冷却を行い、ガラス固化操作を終了する。 An example of a melting furnace operation method for treating radioactive waste liquid using the glass melting furnace according to the present invention is shown in FIG. The feature of this operation method is that it is not necessary to interrupt the operation of the melting furnace in order to remove deposits. The operation procedure is as follows, for example.
(A) The glass raw material and the radioactive liquid waste are charged into the melting tank (continuously charged throughout the operation period).
(B) The glass is heated and melted by energizing the main electrode.
(C) Since electric resistance changes according to the density | concentration of the precipitate in glass, deposition can be estimated by resistance measurement. In addition, the deposit detection is performed by the deposition point detection device in parallel with the electric heating. Note that the deposition location detector is calibrated in advance by utilizing the fact that there is no deposit in the melting tank at the beginning of the operation of the melting furnace.
(D) The above steps (a) to (c) are repeated until the glass holding amount in the melting tank reaches a specified value.
(E) When the glass holding amount in the melting tank reaches a specified value, heating of the falling nozzle is started to flow down the molten glass.
(F) When deposits are detected in the step (c), local heating is performed in the vicinity of the deposition position simultaneously with the falling nozzle heating. The deposit decreases in viscosity with heating and can be selectively flowed down. The local heating device causes the deposit to flow down from the flow nozzle while adjusting the heating output so that the deposit can flow down.
(G) The heating of the flow nozzle is continued until the flow rate of the molten glass reaches a specified value, and the flow of the molten glass is continued.
(H) When the flow-down amount of the molten glass reaches a specified value, the flow-down nozzle is stopped from heating and cooled to finish the glass solidification operation.

このようにして、溶融槽の底部に堆積物が蓄積されても、運転を継続しつつ堆積物を選択的に流下させ、抜き出すことができ、溶融炉を停止する必要がないため、炉の運転効率は格段に向上することになる。   In this way, even if deposits are accumulated at the bottom of the melting tank, the deposits can be selectively flowed down and extracted while continuing operation, and it is not necessary to stop the melting furnace. Efficiency will be greatly improved.

最後に、本発明の物理的根拠となるガラスの特性について説明する。ガラス溶融炉では運転開始とともに溶融炉中にクロム、ルテニウム、パラジウム等の金属酸化物が析出し、時間の経過とともに炉底に堆積する。溶融ガラスは析出物の濃度に応じて図７に示す物性に従い比抵抗が変化することから、運転時に逐次、溶融ガラスの比抵抗を計測することで堆積状況を予測することができる。これにより、溶融炉内の析出物堆積状況を監視する。堆積物は図８に示すとおり温度の上昇に従って粘度が下がる。従って、局所加熱によって堆積物および周辺を加熱することで粘度を下げ、選択的に堆積物を流下させることができる。なお、図８で計測したガラスは、高レベル放射性廃液に含まれているＲｕ、Ｒｈ、Ｐｄの濃度比が一定になるように調製されている。従って図８中のｘ軸にはＲｕＯ2 の濃度が代表として記されているが、実際にはＲｈ、ＰｄもＲｕＯ2 と比例して増減している。 Finally, the characteristics of the glass that is the physical basis of the present invention will be described. In the glass melting furnace, metal oxides such as chromium, ruthenium, and palladium are deposited in the melting furnace as the operation starts, and deposit on the furnace bottom as time passes. Since the specific resistance of molten glass changes in accordance with the physical properties shown in FIG. 7 according to the concentration of precipitates, the deposition status can be predicted by measuring the specific resistance of the molten glass sequentially during operation. Thereby, the deposit accumulation state in the melting furnace is monitored. As shown in FIG. 8, the viscosity of the deposit decreases as the temperature increases. Therefore, by heating the deposit and the surroundings by local heating, the viscosity can be lowered and the deposit can be selectively flowed down. Note that the glass measured in FIG. 8 is prepared so that the concentration ratio of Ru, Rh, and Pd contained in the high-level radioactive liquid waste is constant. Therefore, the concentration of RuO 2 is shown as a representative on the x-axis in FIG. 8, but actually Rh and Pd also increase and decrease in proportion to RuO 2 .

本発明に係るガラス溶融炉の一実施例を示す説明図。Explanatory drawing which shows one Example of the glass melting furnace which concerns on this invention. 本発明に係るガラス溶融炉の他の実施例を示す説明図。Explanatory drawing which shows the other Example of the glass melting furnace which concerns on this invention. 堆積箇所検知装置の他の例を示す説明図。Explanatory drawing which shows the other example of a deposition location detection apparatus. 局所加熱装置の他の例を示す説明図。Explanatory drawing which shows the other example of a local heating apparatus. 局所加熱装置の更に他の例を示す説明図。Explanatory drawing which shows the further another example of a local heating apparatus. ガラス溶融炉の運転方法の一例を示すフロー図。The flowchart which shows an example of the operating method of a glass melting furnace. 溶融ガラスの酸化ルテニウム濃度と温度と比抵抗の関係を示すグラフ。The graph which shows the relationship between a ruthenium oxide density | concentration of molten glass, temperature, and a specific resistance. 溶融ガラスの酸化ルテニウム濃度と温度と粘度の関係を示すグラフ。The graph which shows the relationship between a ruthenium oxide density | concentration of molten glass, temperature, and a viscosity.

符号の説明Explanation of symbols

１０ ガラス溶融炉
１２ 流下ノズル
１４ 溶融槽
１６ 主電極
１８ ガラス原料供給系
２０ ガラス原料
２２ 溶融ガラス
２４ オフガス処理系
２６ 析出物
２８ 堆積物
３０ 底部電極
３２ 抵抗計
３４ 電源 DESCRIPTION OF SYMBOLS 10 Glass melting furnace 12 Flowing nozzle 14 Melting tank 16 Main electrode 18 Glass raw material supply system 20 Glass raw material 22 Molten glass 24 Off-gas treatment system 26 Precipitate 28 Deposit 30 Bottom electrode 32 Resistance meter 34 Power supply

Claims (3)

底部が流下ノズルに向かって下向きに傾斜する構造の溶融槽と、該溶融槽の側壁に配設された複数の主電極を具備し、前記溶融槽内に投入したガラス原料と放射性廃液に前記主電極により直接通電し発生するジュール熱により加熱溶融し、溶融ガラスを流下ノズルから抜き出すようにしたガラス溶融炉において、
前記溶融槽の底部に複数の底部電極が分散埋設されており、前記底部電極間での抵抗計測方式で堆積物を検知することで堆積物の有無及び位置を特定する堆積箇所検知装置と、該堆積箇所検知装置によって特定された堆積箇所の近傍の前記底部電極間で直接通電方式により局所加熱を行う局所加熱装置とを設置し、局所加熱により堆積物の粘度を低下させることで堆積物の選択的な流下による抜き出しを可能にしたことを特徴とするガラス溶融炉。 A melting tank having a structure in which a bottom portion is inclined downward toward the flow nozzle and a plurality of main electrodes disposed on a side wall of the melting tank, and the main material is added to the glass raw material and radioactive waste liquid charged in the melting tank. In a glass melting furnace that is heated and melted by Joule heat that is generated by energizing the electrode directly, and the molten glass is extracted from the flow nozzle.
A plurality of bottom electrodes are distributed and embedded at the bottom of the melting tank, and a deposition location detection device that identifies the presence and position of deposits by detecting deposits with a resistance measurement method between the bottom electrodes ; and Select a deposit by installing a local heating device that performs local heating by direct energization between the bottom electrodes in the vicinity of the deposition location specified by the deposition location detector, and lowering the viscosity of the deposit by local heating A glass melting furnace characterized in that it can be extracted by a typical flow. 底部が流下ノズルに向かって下向きに傾斜する構造の溶融槽と、該溶融槽の側壁に配設された複数の主電極を具備し、前記溶融槽内に投入したガラス原料と放射性廃液に前記主電極により直接通電し発生するジュール熱により加熱溶融し、溶融ガラスを流下ノズルから抜き出すようにしたガラス溶融炉において、A melting tank having a structure in which a bottom portion is inclined downward toward the flow nozzle and a plurality of main electrodes disposed on a side wall of the melting tank, and the main material is added to the glass raw material and radioactive waste liquid charged in the melting tank. In a glass melting furnace that is heated and melted by Joule heat that is generated by energizing the electrode directly, and the molten glass is extracted from the flow nozzle.
前記溶融槽の底部に複数の底部電極が分散埋設されていると共に溶融槽の底部近傍に達するように棒状電極が挿入可能となっており、前記底部電極と棒状電極間での抵抗計測方式で堆積物を検知することで堆積物の有無及び位置を特定する堆積箇所検知装置と、該堆積箇所検知装置によって特定された堆積箇所の近傍の前記底部電極と棒状電極間で直接通電方式により局所加熱を行う局所加熱装置とを設置し、局所加熱により堆積物の粘度を低下させることで堆積物の選択的な流下による抜き出しを可能にしたことを特徴とするガラス溶融炉。A plurality of bottom electrodes are dispersedly embedded at the bottom of the melting tank, and a rod-shaped electrode can be inserted so as to reach the vicinity of the bottom of the melting tank, and is deposited by a resistance measurement method between the bottom electrode and the rod-shaped electrode. A deposition spot detection device that identifies the presence and position of deposits by detecting an object, and local heating by a direct energization method between the bottom electrode and the rod electrode in the vicinity of the deposition spot identified by the deposition spot detection device A glass melting furnace characterized in that a local heating device is installed and the viscosity of the deposit is reduced by local heating, thereby enabling the sediment to be extracted by selective flow down. 請求項１又は２記載のガラス溶融炉を使用し、主電極によるガラス溶融運転を継続しつつ、堆積箇所検知装置で特定された堆積箇所を、局所加熱装置によって局所加熱することにより、堆積物を選択的に流下させて抜き出すように運転するガラス溶融炉の運転方法。


Using a glass melting furnace according to claim 1 or 2, wherein, while continuing the glass melting operation by the main electrodes, has been deposited location specific in deposition point detecting device, by local heating by the local heating device, deposits A method of operating a glass melting furnace that operates to selectively flow down and extract.


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JPH04332859A (en) * 1991-05-08 1992-11-19 Power Reactor & Nuclear Fuel Dev Corp Device for detecting conductive insoluble constituent within high-temperature melt
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