JP4262428B2

JP4262428B2 - Water leak detection method in metallurgical furnace

Info

Publication number: JP4262428B2
Application number: JP2001339046A
Authority: JP
Inventors: 幸介山下; 智昭田中; 眞角
Original assignee: Nittetsu Plant Designing Corp; Nippon Steel Corp
Current assignee: Nippon Steel Corp; Nippon Steel Plant Designing Corp
Priority date: 2001-11-05
Filing date: 2001-11-05
Publication date: 2009-05-13
Anticipated expiration: 2021-11-05
Also published as: JP2003139473A

Description

【０００１】
【発明の属する技術分野】
本発明は、冶金炉における水漏れ検知方法、例えば、高炉・転炉・電気炉等で製造された炭素含有の粗溶湯を真空下において精錬する際に発生する排ガスの処理装置、とりわけ水冷ダクト・排ガス冷却装置等の冷却水を使用した装置における水漏れを検知する方法に関する。
【０００２】
【従来の技術】
大気精錬炉には転炉・電気炉・ＡＯＤ等、真空精錬炉にはＶＯＤ，ＡＯＤ，ＲＨ等種々のタイプがあるが、これらの大気・真空精錬炉を含めた冶金炉の排ガス処理において、発生する高温の排ガスを冷却する必要がある。このためダクトの途中に水冷式のガスクーラーを設けたり、また途中のダクトにおいて水冷を行うことがある。この場合高温排ガスと多量の冷却水とで熱交換が行われるが、配管・ダクトの磨耗・減肉、或いは熱応力による割れ等により、冷却水が配管・ダクトから排ガス流路内に漏れることがある。しかし、排ガス処理設備は一般に密閉されているため内部の水漏れの状況が把握できない。そのため内部の水漏れを認識できないまま操業を続行し、水漏れが激しくなって真空度の著しい低下、或いはダストの水濡れによる系外への搬出不能等の設備・操業トラブルの発生に至ることがあった。
【０００３】
そこで、ある頻度で計画的に操業を止め、ダクト内の点検・ガスクーラーの点検を実施していた。また、ガスクーラー下部のダスト溜り部に静電容量式の検知棒を設置し、ダストが漏水により濡れて静電容量が変化することを利用して漏水を検知することが行われていた。
【０００４】
【発明が解決しようとする課題】
しかしながら、計画的に操業を止めて点検する場合、設備の稼動率を低下させ生産性を阻害する。一方、前述の静電容量式の検知棒では、ダストの濡れ状態による検知棒の静電容量の調整が難しい。例えば、少量の漏水では、温度が高かったり或いは真空下では蒸気となり易いため、漏水を検知することが出来ず、大量の漏水が検知の前提とならざるを得ない。従って、漏水を軽微な状態で事前に検知することが極めて難しかった。
【０００５】
本発明は、上述した大気精錬もしくは真空精錬設備の如き冶金炉における排ガス処理装置において、とりわけ水冷ダクト・排ガス冷却装置等の冷却水を使用した装置における水漏れを高精度に検知することを目的とし、処理中に僅かな量の水漏れも検知可能であり、しかも装置の管理維持が容易で耐久性に優れた検知方法を提供するものである。
【０００６】
【課題を解決するための手段】
本発明は、冶金炉の排ガス処理装置において、排ガス流路内の水漏れを間接的に常時監視するため、水漏れした水分が蒸発し排ガス中の湿度を高めることに着目した。実機にて試験を繰り返し、この排ガス中湿度変化を常時監視しておけば、水漏れのかなり初期から検知可能であることが判明し、設備化に成功した。一方、操業上、水分を含有する副材等を冶金炉内に添加すると、炉内反応により排ガス中湿度が上昇することがある。また、冶金炉内で精錬時の熱源とするため、炭化水素を含有した気体燃料或いは固体燃料等を燃焼させる場合、同様に排ガス中湿度が上昇する。本発明者らは、その発生形態、即ち湿度上昇レベル及び上昇継続時間等を詳細に調査し、水冷設備の水漏れによる湿度上昇と操業による湿度上昇と判別することができる水漏れ検知方法を見出した。
【０００７】
その要旨は以下の通りである。
（１）溶融金属を精錬する冶金炉から発生する高温の排ガスを冷却した後、或いは冷却後除塵して処理した後に、排ガスの一部から排ガス中の水蒸気濃度もしくは水蒸気分圧の少なくとも１つの測定と同時に、ＣＯ、ＣＯ _２、Ｏ _２、Ｈ _２のうち少なくとも１つのガス濃度或いは分圧の測定を行い、水蒸気濃度又は分圧変化の増減及びその程度を予め認識されたパターンと比較して、濃度又は分圧変化が、排ガス経路からの漏水による濃度又は分圧増加に基づくものか、或いは他の要因に基づく一時的反応による濃度又は分圧の増加であるか、を判断して検知、監視することを特徴とする冶金炉における水漏れ検知方法。
（２）前記（１）の水漏れ検知方法において、排ガスの一部を吸引ポンプで吸引・分離し、更にその一部を第２の吸引ポンプにて水蒸気濃度計或いは水蒸気分圧計に導入して、排ガス中の水蒸気濃度もしくは水蒸気分圧の少なくとも１つを測定して、これを水漏れ検知制御或いは監視のうち少なくともいずれかに用いることを特徴とする冶金炉における水漏れ検知方法。
【０００８】
【発明の実施の形態】
本発明の実施例を図面により説明する。なお、図示する実施例は真空精錬炉の排ガス処理設備の例であるが、本発明はこれに限ることなく金属の溶解・精錬に用いる他の冶金炉（大気精錬炉を含む）においても、その排ガス冷却が間接水冷を含む冷却方式であれば、適用することができる。一般的に、水冷されたダクト・クーラー等から精錬排ガス系内に漏水した場合、漏水が水蒸発となる量は、系内雰囲気が大気より真空の方がより大きい。よって、本発明の漏水検知方法及び装置は、真空精錬装置においてより効果的に漏水が検知され易いと言える。
【０００９】
図１に実施例の設備全体概念図を示す。真空精錬炉１で発生した排ガス４は水冷ダクト２を通り、それに接続するガスクーラー５に送られそこで冷却される。その後ガスクーラー５からダクト３を通り乾式集塵機６に送給されて除塵され、さらにダクト３を経て真空排気装置７に送られてから大気放散される。
【００１０】
ここで、集塵機６の後段におけるダクト３から湿度計及び分析計用排ガス吸引導管８を分岐することで、排ガスの一部を分岐吸引して湿度計９に導入するようにしている。その結果、該湿度計９において排ガスの湿度が測定されるが、この位置には排ガスの分析計も併設されている。実施例では排ガス湿度計は集塵機６の後段に設置した例を示しているが、ガスクーラー５の後段に設置してもよい。また、ここで併設されている分析計は同一場所のケースもあるが、真空排気装置７の後段或いは集塵機６後段に湿度計とは別個に設置するケースもある。
【００１１】
分析計を併設したのは、排ガスの湿度を測定する際に、ＣＯ、ＣＯ₂、Ｏ₂、Ｈ₂等のガス濃度或いは分圧の少なくとも１つを同時に測定するためである。これらの分析値は、冶金炉内の反応の進行状況を把握して、冶金炉へのガス吹込み、副材・冷材投入等のオペレーションガイダンスとしたり、冶金操作完了の判断情報としたりすることに利用される。また、湿度計の測定値も漏水の判断情報とする以外に、これらのガス分析情報とともに前述の炉内反応状況を判断する情報としても利用可能である。
【００１２】
次に本装置の使用方法を説明する。
真空精錬炉１の排ガス処理において、発生する高温の排ガスを冷却するためダクトの途中にガスクーラー５を設け、また途中のダクトは水冷を行う。本対策の方式では、集塵機後段で排ガスの相対的な湿度が常時測定・監視される。例えば真空精錬中、ガスクーラー５の水管に亀裂が入り、冷却水が排ガス中に噴出したとする。この場合漏水は高温の排ガスによって蒸発し、排ガスの水蒸気分圧が上昇するため、後段に設置された湿度計９はその相対的な湿度の上昇を検知することができる。即ち、排ガス流路内が漏水無く正常な状態での排ガスの相対湿度に対して、高い湿度を一定時間継続した場合を漏水発生として判断して・設備・操業上の処置を行う。なお、湿度だけを検知することに限らず、水蒸気分圧を検知してもよい。
【００１３】
設備・操業上の処置の具体例としては、漏水検知後直ちに漏水補修作業に必要な措置、例えば冶金炉と排気ダクトとの縁切り、或いはバイパス経路を装備している場合はバイパス側への経路変更等を講じてから、漏水箇所の迅速な補修作業を行うことが重要である。漏水の早期の検知は、補修箇所も軽微である場合が多く、補修が容易で短期に終了する。また、場合によっては、警報だけを出し、適宜機器の運転停止などを行うこともできる。
【００１４】
通常、排ガスの一部を分離して排ガス中の湿度測定或いはガス分析測定を行う場合、吸引ポンプによりダクト内排ガスを吸引して直接分析計に分析用排ガスを供給する。よって吸引ポンプは１段で良い。しかし、真空下の排ガスの湿度測定或いはガス分析測定を行う場合、吸引ポンプを２段に構える必要がある。以下その理由を述べる。真空下の排ガスを吸引する場合、分析装置に供給されるガスは大気圧相当の圧力となるため、同一吸引ポンプによって真空中から吸引される排ガスの絶対流量（標準状態換算のガス流量）は、真空度によって大きく変動する。即ち、吸引排ガスの絶対流量は低真空時と比較して高真空時はかなり小さくなる。よって、同一吸引ポンプを使用する場合、湿度計或いはガス分析計側に供給されるガス流量は真空度により大きく変動する。一方、湿度測定器或いはガス分析器の測定精度を高度に維持するためにはこれらの計器に供給されるガス流量の変動は回避されねばならない。この対策として、吸引ポンプを２段に構える。
【００１５】
すなわち、図２に示すように、排気ダクト３中の真空排ガス４を比較的容量の大きいポンプ１１にて吸引し、その吐出側の大気圧相当の排ガスの一部を更に第２の吸引ポンプ１２により吸引して分析装置９に供給する。第２段のポンプ１２に吸引されない排ガスは、排出管１３を介して大気放出ガス１５として放出されるか、同一ダクトの下流部に放出される。この放出ガス流量は、吸引されるダクト内真空度が高い場合は少なく、真空度が低い場合は多くなる。こうして測定された排ガス中の水蒸気濃度もしくは水蒸気分圧は、操作室の監視パネルに表示される。この表示された測定値をオペレーターが常時監視し、通常より高い値となった場合に前述の操業・設備処置を実施する。また、予め制御装置に排ガス中の水蒸気濃度もしくは水蒸気分圧の異常を検知するプログラムを組んでおき、自動的に警報を発生せしめたり、装置を停止する等の操業上の自動シーケンスにつなげる。なお、分析装置９からも排出管１４を通って大気放出ガス１５が放出される。
【００１６】
なお、真空精錬中の排ガスの水蒸気分圧は、機器の漏水以外の要因で上昇するケースもある。真空精錬炉には、操業中合金鉄・冷材・生石灰等の副原料が投入される。これらの副原料は多少の水分を含有しているため、投入後には排ガス中の水蒸気分圧が一時的に上昇する。特に、生石灰等の副材は吸湿し易く水分が多いため投入後の水蒸気発生量は著しく高くなる。よって、相対湿度の上昇を短絡的に漏水と判断することは誤検知となる。そこで、本発明者らが相対湿度の挙動を詳細に調査した結果、漏水による湿度上昇は継続的であり・多少の変動はあるが一度上昇した湿度は処理終了まで継続して高い状態にある。一方、合金・冷材・副材等の精錬炉内添加による湿度上昇は、短期的であり、投入後一定時間経過すると湿度は投入前のレベルに低減することが判明した。よって、この湿度レベルの挙動の差異を利用して、冷却水系統からの漏水か否かを判別することが可能である。
【００１７】
また、漏水以外の排ガス中湿度上昇の他の要因として、冶金炉内で精錬時の熱源を目的に、炭化水素を含有した気体燃料或いは固体燃料等を燃焼させる場合がある。例えば、操業中、ＬＮＧ，ＬＰＧ，灯油等の炭化水素系燃料を冶金炉内で燃焼させると、排ガス中に多量の水蒸気が混入される。しかし、これらは供給タイミング及び供給量が明確となっており、排ガスへの水蒸気の混入量は比較的精度良く推定可能である。よって排ガス中の水蒸気分圧の測定結果からこれらの影響を分離することは充分可能である。
【００１８】
具体的には、漏水と判断するには、湿度変化の増減及びその湿度レベルの事前設定と、その時炉内に添加された合金・冷材・副材等の成分や量から投入後の湿度上昇継続時間を事前に求めて同様に設定し、更に炭化水素含有燃料の供給時間及び供給量から推定される湿度上昇を事前設定しておき、連続的な湿度及び湿度上昇時の時間の測定値が、前記の設定湿度レベル（パターン）と時間レベルを越えたとき、漏水と判断して自動的に警告信号或いは制御信号が出力するようにしておけばよい。
【００１９】
【発明の効果】
以上述べたように、排ガスの湿度を測定・監視することにより、排ガス流路内の少量の漏水が検知可能となり、早期に漏水が検出されると同時に、漏水検知の信頼性も飛躍的に向上した。これによって得られる設備・操業上の効果は以下の通りである。
（１）漏水時の排ガス中水蒸気分圧上昇による精錬炉内の真空度悪化を最小限に抑制することができ、精錬上の冶金効果の悪化を回避できた。
（２）漏水が早期に発見できることにより、漏水箇所の補修が初期段階で出来るので、修理整備作業が容易となり、補修時間及びコストの削減が可能となる。
（３）漏水の発見が遅れることによるダスト滞留箇所のダスト固着が防止され、その後のダスト除去に多大な時間と費用を費やすことが回避できた。
（４）対策前は、漏水時ガスクーラーの水管或いは煙管表面に付着したダストが固着して排ガス流路が狭くなり、ガスクーラーの圧力損失が大きくなり精錬炉内の真空度が悪化していた。本発明により、ダストの固着が回避され、良好な真空度が維持可能となった。
（５）対策前は、漏水による水蒸気含有排ガスにより、バグフィルターの濾布表面に付着したダストが固着して、集塵機の圧力損失が増大していた。本発明により、ダスト固着が回避され、精錬炉内の真空度を良好に維持することが可能となった。
（６）ガスクーラー或いは集塵機内のダスト搬出として、ダストの気体圧送方式を採用している場合、漏水が多くなるとダストが固着して、ダストの気体圧送が著しく阻害される。本対策により、漏水が初期に検知されるとダストの固着が無くなり、ダスト圧送トラブルも皆無となった。
（７）漏水箇所が真空精錬炉に近い場合、漏水の発見が遅れ漏水量が多くなると、精錬炉内に漏水が逆流して溶湯内に漏水が流れ込み水蒸気爆発に至る危険性があった。本対策により、漏水の小さい段階での発見・補修が可能となり、水蒸気爆発に至る危険性は極めて小さくなった。
（８）従来の静電容量型検知棒の様な漏水検知方法では・ガスクーラー等のダスト溜り部へ設置するといった限定された箇所での検出であった。本発明では、排ガス中の相対的な水蒸気量を測定するため、排ガス流路全体を監視することができ、検出時は設備全体を調査し早期に設備対策を講じることが可能となった。
【図面の簡単な説明】
【図１】真空精錬設備の排ガス処理装置における本発明による水漏れ検知装置を模式的に示す図である。
【図２】本発明による水漏れ検知装置における湿度計及び分析計用排ガス導入及び排気フローを模式的に示す図である。
【符号の説明】
１真空精錬炉
２排ガス水冷ダクト
３排ガスダクト（非水冷）
４排ガス
５間接水冷式ガスクーラー
６集塵機
７真空排気装置
８湿度計及び分析計用排ガス吸引導管
９湿度計（分析計）
１０湿度計及び分析計での測定値の信号
１１排気ダクトから排ガスを吸引する第１段吸引ポンプ
１２第１段吸引ポンプで供給される排ガスを湿度計及び分析計に供給する第２段吸引ポンプ
１３第１段吸引ポンプで供給される排ガス中余剰となった排ガスの排出管
１４湿度計及び分析計で使用されたガスの排出管
１５大気放出ガス[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for detecting a water leak in a metallurgical furnace, for example, a treatment apparatus for exhaust gas generated when refining a carbon-containing crude molten metal produced in a blast furnace, converter, electric furnace, etc., in particular a water-cooled duct, The present invention relates to a method for detecting water leakage in an apparatus using cooling water such as an exhaust gas cooling apparatus.
[0002]
[Prior art]
There are various types of atmospheric smelting furnaces such as converters, electric furnaces and AODs, and vacuum smelting furnaces of various types such as VOD, AOD and RH. These are generated in exhaust gas treatment of metallurgical furnaces including these atmospheric and vacuum smelting furnaces. It is necessary to cool the hot exhaust gas. For this reason, a water-cooled gas cooler may be provided in the middle of the duct, or water cooling may be performed in the middle of the duct. In this case, heat exchange is performed between the high-temperature exhaust gas and a large amount of cooling water, but cooling water may leak from the piping / duct into the exhaust gas flow path due to wear / thinning of pipes / ducts or cracking due to thermal stress. is there. However, since the exhaust gas treatment facility is generally sealed, the state of water leakage inside cannot be grasped. Therefore, the operation may continue without recognizing the internal water leakage, and the water leakage may become severe, resulting in a significant drop in vacuum, or equipment / operation troubles such as inability to carry out of the system due to wetness of dust. there were.
[0003]
Therefore, the operation was stopped systematically at a certain frequency, and the inside of the duct and the gas cooler were inspected. In addition, a capacitance type detection rod is installed in a dust reservoir at the lower part of the gas cooler, and the leakage of water is detected by utilizing the fact that the capacitance changes due to the dust getting wet due to the leakage of water.
[0004]
[Problems to be solved by the invention]
However, when the operation is systematically stopped and inspected, the operation rate of the equipment is lowered and productivity is hindered. On the other hand, it is difficult to adjust the capacitance of the detection rod due to the wet state of dust in the above-described capacitance detection rod. For example, when a small amount of water leaks, the temperature is high or it is likely to become steam under vacuum, so that the water leakage cannot be detected, and a large amount of water leakage must be a prerequisite for detection. Therefore, it was extremely difficult to detect water leakage in a slight state in advance.
[0005]
An object of the present invention is to detect water leakage with high accuracy in an exhaust gas treatment apparatus in a metallurgical furnace such as the above-described air refining or vacuum refining equipment, particularly in an apparatus using cooling water such as a water cooling duct and an exhaust gas cooling apparatus. Further, it is possible to detect a slight amount of water leakage during processing, and to provide a detection method that is easy to maintain and maintain the apparatus and has excellent durability.
[0006]
[Means for Solving the Problems]
In the exhaust gas treatment apparatus of a metallurgical furnace, the present invention pays attention to the fact that water leaking in the exhaust gas flow path is indirectly and constantly monitored, so that the leaked water evaporates and the humidity in the exhaust gas is increased. Repeated tests with actual equipment, it was found that if this humidity change in the exhaust gas was constantly monitored, it was found that water leaks could be detected from the very beginning, and the installation was successful. On the other hand, when a secondary material containing water is added to the metallurgical furnace for operation, the humidity in the exhaust gas may increase due to the reaction in the furnace. Moreover, in order to use as a heat source at the time of refining in a metallurgical furnace, when gas fuel containing hydrocarbons or solid fuel is burned, the humidity in exhaust gas similarly increases. The present inventors have investigated in detail the form of occurrence, that is, the level of humidity rise and duration of rise, and found a water leak detection method capable of discriminating between a humidity rise due to a water leak in a water cooling facility and a humidity rise due to operation. It was.
[0007]
The summary is as follows.
(1) After cooling high-temperature exhaust gas generated from a metallurgical furnace for refining molten metal, or after removing dust and processing after cooling, at least one of the water vapor concentration or water vapor partial pressure in the exhaust gas from a part of the exhaust gas Simultaneously with the measurement, the gas concentration or partial pressure of at least one of CO, CO ₂ , O ₂ , and H ₂ is measured, and the increase or decrease in water vapor concentration or partial pressure change and the degree thereof are compared with a previously recognized pattern. Detecting whether the change in concentration or partial pressure is based on an increase in concentration or partial pressure due to water leakage from the exhaust gas path, or an increase in concentration or partial pressure due to a temporary reaction based on other factors, A method for detecting water leakage in a metallurgical furnace, characterized by monitoring.
(2) In the water leakage detection method (1), a part of the exhaust gas was sucked and separated by the suction pump, further introducing a part of the second steam concentration meter or the water vapor partial pressure gauge at the suction pump A method for detecting water leakage in a metallurgical furnace, wherein at least one of water vapor concentration or water vapor partial pressure in exhaust gas is measured and used for at least one of water leakage detection control and monitoring.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. The illustrated embodiment is an example of an exhaust gas treatment facility for a vacuum smelting furnace, but the present invention is not limited to this, and other metallurgical furnaces (including atmospheric smelting furnaces) used for melting and refining metals can also be used. If the exhaust gas cooling is a cooling system including indirect water cooling, it can be applied. In general, when water leaks into a refining exhaust gas system from a water-cooled duct, cooler, or the like, the amount of water that evaporates becomes water evaporation is greater in a system atmosphere than in air. Therefore, it can be said that the water leakage detection method and apparatus of the present invention are more effective in detecting water leakage in a vacuum refining apparatus.
[0009]
FIG. 1 is a conceptual diagram of the entire facility according to the embodiment. The exhaust gas 4 generated in the vacuum smelting furnace 1 passes through the water cooling duct 2 and is sent to the gas cooler 5 connected thereto to be cooled there. After that, the gas cooler 5 passes through the duct 3 and is sent to the dry dust collector 6 for dust removal. Further, the dust is sent to the vacuum exhaust device 7 through the duct 3 and then diffused into the atmosphere.
[0010]
Here, by branching the hygrometer and analyzer exhaust gas suction conduit 8 from the duct 3 in the subsequent stage of the dust collector 6, a part of the exhaust gas is branched and sucked and introduced into the hygrometer 9. As a result, the humidity of the exhaust gas is measured by the hygrometer 9, and an exhaust gas analyzer is also provided at this position. In the embodiment, an example in which the exhaust gas hygrometer is installed at the rear stage of the dust collector 6 is shown, but it may be installed at the rear stage of the gas cooler 5. In addition, there are cases where the analyzers provided in the same place are located in the same place, but there are also cases where the analyzers are installed separately from the hygrometer in the rear stage of the vacuum exhaust device 7 or the rear stage of the dust collector 6.
[0011]
The reason why the analyzer is provided is to simultaneously measure at least one of gas concentrations or partial pressures of CO, CO ₂ , O ₂ , H _2, etc. when measuring the humidity of the exhaust gas. These analysis values should be used to grasp the progress of the reaction in the metallurgical furnace, and to provide operation guidance for gas injection into the metallurgical furnace, charging of secondary materials and cold materials, etc., and judgment information for the completion of metallurgical operations. Used for Further, the measured value of the hygrometer can be used as information for determining the above-described reaction state in the furnace together with the gas analysis information, in addition to the information for determining water leakage.
[0012]
Next, the usage method of this apparatus is demonstrated.
In the exhaust gas treatment of the vacuum refining furnace 1, a gas cooler 5 is provided in the middle of the duct to cool the generated high temperature exhaust gas, and the midway duct is water-cooled. In this measure, the relative humidity of the exhaust gas is constantly measured and monitored after the dust collector. For example, during vacuum refining, it is assumed that the water pipe of the gas cooler 5 is cracked and cooling water is ejected into the exhaust gas. In this case, the leaked water evaporates due to the high-temperature exhaust gas, and the water vapor partial pressure of the exhaust gas rises. Therefore, the hygrometer 9 installed in the subsequent stage can detect an increase in the relative humidity. That is, when a high humidity is maintained for a certain period of time with respect to the relative humidity of the exhaust gas in a normal state with no leakage in the exhaust gas flow path, it is determined that water leakage has occurred, and equipment / operational measures are taken. It should be noted that the water vapor partial pressure may be detected in addition to detecting only the humidity.
[0013]
Specific examples of equipment / operational measures include measures necessary for water leakage repair work immediately after leakage detection, such as cutting the metallurgical furnace and exhaust duct, or changing the bypass route if a bypass route is installed. It is important to carry out quick repair work for leaked parts after taking such measures. Early detection of water leakage often involves minor repairs, and repairs are easy and can be completed in a short time. In some cases, only an alarm can be issued, and the operation of the device can be stopped as appropriate.
[0014]
Usually, when a part of the exhaust gas is separated and the humidity measurement or gas analysis measurement in the exhaust gas is performed, the exhaust gas in the duct is sucked by the suction pump and the analysis exhaust gas is directly supplied to the analyzer. Therefore, the suction pump may be one stage. However, when performing humidity measurement or gas analysis measurement of exhaust gas under vacuum, it is necessary to provide a suction pump in two stages. The reason is described below. When the exhaust gas under vacuum is sucked, the gas supplied to the analyzer becomes a pressure equivalent to atmospheric pressure, so the absolute flow rate of exhaust gas sucked from the vacuum by the same suction pump (gas flow rate in terms of standard state) is It varies greatly depending on the degree of vacuum. That is, the absolute flow rate of the suction exhaust gas is considerably smaller at high vacuum than at low vacuum. Therefore, when the same suction pump is used, the flow rate of the gas supplied to the hygrometer or gas analyzer side varies greatly depending on the degree of vacuum. On the other hand, in order to maintain the measurement accuracy of the humidity measuring instrument or the gas analyzer at a high level, fluctuations in the gas flow rate supplied to these instruments must be avoided. As a countermeasure, a suction pump is provided in two stages.
[0015]
That is, as shown in FIG. 2, the vacuum exhaust gas 4 in the exhaust duct 3 is sucked by the pump 11 having a relatively large capacity, and a part of the exhaust gas corresponding to the atmospheric pressure on the discharge side is further sucked by the second suction pump 12. The sample is sucked and supplied to the analyzer 9. Exhaust gas that is not sucked into the second-stage pump 12 is discharged as the atmospheric discharge gas 15 through the discharge pipe 13 or is discharged downstream of the same duct. This discharge gas flow rate is small when the degree of vacuum in the duct to be sucked is high and increases when the degree of vacuum is low. The water vapor concentration or water vapor partial pressure in the exhaust gas thus measured is displayed on the monitoring panel in the operation room. The displayed measurement value is constantly monitored by the operator, and when the value becomes higher than usual, the above-mentioned operation / equipment treatment is performed. In addition, a program for detecting abnormalities in water vapor concentration or water vapor partial pressure in the exhaust gas is built in the control device in advance, and this is connected to an automatic operation sequence such as automatically generating an alarm or stopping the device. Note that the atmospheric emission gas 15 is also released from the analyzer 9 through the discharge pipe 14.
[0016]
In some cases, the water vapor partial pressure of the exhaust gas during vacuum refining increases due to factors other than the leakage of equipment. In the vacuum refining furnace, auxiliary raw materials such as alloy iron, cold material and quicklime are put into operation. Since these auxiliary materials contain some moisture, the water vapor partial pressure in the exhaust gas temporarily rises after the introduction. In particular, sub-materials such as quick lime are easy to absorb moisture and have a large amount of moisture, so that the amount of water vapor generated after charging becomes remarkably high. Therefore, it is a false detection to determine that the increase in relative humidity is short-circuit water leakage. Therefore, as a result of detailed investigations on the behavior of the relative humidity by the present inventors, the humidity increase due to water leakage is continuous. Although there is some fluctuation, the humidity once increased continues to be high until the end of the treatment. On the other hand, the increase in humidity due to the addition of alloys, cold materials, secondary materials, etc. in the refining furnace is short-term, and it has been found that the humidity decreases to the level before charging after a certain period of time has elapsed after charging. Therefore, it is possible to determine whether or not there is water leakage from the cooling water system by utilizing the difference in behavior of the humidity level.
[0017]
Further, as another factor of increasing humidity in exhaust gas other than water leakage, gaseous fuel or solid fuel containing hydrocarbon may be burned for the purpose of heat source during refining in a metallurgical furnace. For example, when a hydrocarbon fuel such as LNG, LPG, or kerosene is burned in a metallurgical furnace during operation, a large amount of water vapor is mixed in the exhaust gas. However, the supply timing and supply amount of these components are clear, and the amount of water vapor mixed into the exhaust gas can be estimated with relatively high accuracy. Therefore, it is possible to separate these effects from the measurement result of the water vapor partial pressure in the exhaust gas.
[0018]
Specifically, in order to judge a water leak, increase / decrease in humidity change and prior setting of the humidity level, and the increase in humidity after charging from the components and amounts of alloy, cold material, secondary material, etc. added to the furnace at that time The duration is determined in advance and set in the same manner, and the humidity increase estimated from the supply time and supply amount of the hydrocarbon-containing fuel is set in advance. When the set humidity level (pattern) and time level are exceeded, it is determined that water leaks and a warning signal or control signal is automatically output.
[0019]
【The invention's effect】
As mentioned above, by measuring and monitoring the humidity of the exhaust gas, it is possible to detect a small amount of water leakage in the exhaust gas flow path, and at the same time the water leakage is detected at the same time, the reliability of water leakage detection is dramatically improved. did. The equipment / operational effects obtained from this are as follows.
(1) Deterioration of the degree of vacuum in the refining furnace due to an increase in the partial pressure of water vapor in the exhaust gas at the time of water leakage can be suppressed to a minimum, and deterioration of the metallurgical effect on refining can be avoided.
(2) Since water leakage can be detected at an early stage, repair of the water leakage point can be performed at an early stage, so that repair work can be facilitated, and repair time and cost can be reduced.
(3) It was possible to prevent dust from adhering to the dust staying location due to the delayed discovery of water leakage, and to avoid spending much time and money on the subsequent dust removal.
(4) Before countermeasures, dust adhering to the water pipe or smoke pipe surface of the gas cooler at the time of leakage leaked, narrowing the exhaust gas flow path, increasing the pressure loss of the gas cooler, and worsening the degree of vacuum in the refining furnace . According to the present invention, adhesion of dust is avoided, and a good degree of vacuum can be maintained.
(5) Before the countermeasure, the dust adhering to the filter cloth surface of the bag filter was fixed by the steam-containing exhaust gas due to water leakage, and the pressure loss of the dust collector was increased. According to the present invention, dust sticking is avoided, and the degree of vacuum in the refining furnace can be maintained well.
(6) In the case of adopting a dust gas pressure feeding system as dust discharge in the gas cooler or the dust collector, if the water leakage increases, the dust adheres and the dust gas pressure feeding is significantly hindered. As a result of this measure, when water leakage was detected in the initial stage, the dust was not stuck, and there was no problem with dust pumping.
(7) When the leak location was close to the vacuum smelting furnace, if the leak was delayed and the amount of leak increased, there was a risk that the leak flowed back into the smelting furnace and the leaked water flowed into the molten metal, resulting in a steam explosion. This measure made it possible to detect and repair water leakage at a small stage, and the risk of a steam explosion was extremely small.
(8) In a conventional water leakage detection method such as a capacitance type detection rod, detection was performed at a limited location such as being installed in a dust reservoir such as a gas cooler. In the present invention, since the relative amount of water vapor in the exhaust gas is measured, it is possible to monitor the entire exhaust gas flow path, and at the time of detection, it is possible to investigate the entire facility and take measures for the facility at an early stage.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a water leak detection device according to the present invention in an exhaust gas treatment device of a vacuum refining facility.
FIG. 2 is a diagram schematically showing exhaust gas introduction and exhaust gas flow for a hygrometer and an analyzer in a water leak detection apparatus according to the present invention.
[Explanation of symbols]
1 Vacuum refining furnace 2 Exhaust gas water cooling duct 3 Exhaust gas duct (non-water cooling)
4 Exhaust gas 5 Indirect water-cooled gas cooler 6 Dust collector 7 Vacuum exhaust device 8 Exhaust gas suction conduit 9 for hygrometer and analyzer Hygrometer (analyzer)
10 Signal of measurement value in hygrometer and analyzer 11 First stage suction pump 12 for sucking exhaust gas from exhaust duct Second stage suction pump for supplying exhaust gas supplied by first stage suction pump to hygrometer and analyzer 13 Exhaust gas exhaust pipe 14 surplus in the exhaust gas supplied by the first stage suction pump 14 Exhaust gas exhaust pipe 15 used in hygrometer and analyzer 15

Claims

After cooling high-temperature exhaust gas generated from a metallurgical furnace for refining molten metal, or after removing dust after cooling and processing, at least one measurement of water vapor concentration or water vapor partial pressure in the exhaust gas from a part of the exhaust gas , Measure the concentration or partial pressure of at least one of CO, CO ₂ , O ₂ , and H ₂ , compare the increase or decrease in water vapor concentration or partial pressure change, and its degree with a previously recognized pattern, To detect and monitor whether the partial pressure change is based on an increase in concentration or partial pressure due to leakage from the exhaust gas path, or an increase in concentration or partial pressure due to a temporary reaction based on other factors A method for detecting water leakage in a metallurgical furnace.

In water leak detection method of claim 1 wherein a portion of the exhaust gas was sucked and separated by the suction pump, further by introducing a part of the second steam concentration meter or the water vapor partial pressure gauge at the suction pump, the exhaust gas A method for detecting a water leak in a metallurgical furnace, wherein at least one of a water vapor concentration or a water vapor partial pressure is measured and used for at least one of water leak detection control and monitoring.