JP2003193125A - Method and system for controlling vacuum degree in evacuating facility - Google Patents
Method and system for controlling vacuum degree in evacuating facilityInfo
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- JP2003193125A JP2003193125A JP2001391274A JP2001391274A JP2003193125A JP 2003193125 A JP2003193125 A JP 2003193125A JP 2001391274 A JP2001391274 A JP 2001391274A JP 2001391274 A JP2001391274 A JP 2001391274A JP 2003193125 A JP2003193125 A JP 2003193125A
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- Prior art keywords
- vacuum
- degree
- exhaust gas
- valve
- refining furnace
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- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、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
錬する工程において、真空排気設備における真空度制御
方法及びその装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling the degree of vacuum in a vacuum exhaust facility in the step of refining a carbon-containing crude molten metal produced in a blast furnace, a converter, an electric furnace or the like under vacuum.
【０００２】[0002]
【従来の技術】真空精錬炉は、ＶＯＤ，ＡＯＤ，ＲＨ，
ＲＥＤＡ等種々のタイプがあるが、炉内を真空にするた
めの真空排気設備は必須の装備である。こうした真空精
錬炉を工業的に真空にする真空排気設備は、一般に、エ
ジェクターを多段に組合せることにより所定の炉内真空
度を達成している。真空精錬炉における精錬の進行に合
わせて真空度を制御するが、通常は多段のエジェクター
の内、目標とする真空度に見合った能力の単数或いは複
数のエジェクターを稼動させ、所定の真空度を確保して
いる。2. Description of the Related Art Vacuum refining furnaces use VOD, AOD, RH,
There are various types such as REDA, but the vacuum exhaust equipment for evacuating the furnace is an essential equipment. The vacuum exhaust equipment for industrially vacuuming such a vacuum refining furnace generally achieves a predetermined degree of vacuum in the furnace by combining ejectors in multiple stages. The degree of vacuum is controlled according to the progress of refining in the vacuum refining furnace, but normally, among multiple ejectors, one or more ejectors with the capacity corresponding to the target degree of vacuum are operated to secure the prescribed degree of vacuum. is doing.
【０００３】一方、工業的に使用される真空排気装置の
一つに水封式真空ポンプがある。これは単独で使用する
場合、キャビテーションの問題から到達真空度として８
kPa程度であり、それ以上の真空度を得る場合は、前述
のエジェクターを併用する必要がある。エジェクターの
みを使用して真空度制御を行う場合は、エジェクターの
前に窒素或いは空気等を吹込み、その吹込み流量を制御
することにより、炉内或いはダクトの真空度が制御され
る。On the other hand, a water-sealed vacuum pump is one of the vacuum pumps used industrially. When this is used alone, the ultimate vacuum is 8 due to the problem of cavitation.
When the degree of vacuum is higher than kPa, it is necessary to use the aforementioned ejector together. When the degree of vacuum is controlled using only the ejector, nitrogen or air is blown in front of the ejector, and the flow rate of the blow is controlled to control the degree of vacuum in the furnace or the duct.
【０００４】[0004]
【発明が解決しようとする課題】溶鋼を真空下で気体酸
素を使用して精錬する場合、脱炭反応により生成するＣ
Ｏガスにより、溶鋼の湯面から地金・スプラッシュが真
空精錬炉の上部に向かって吹上げてくる。これらは真空
度が高くなると（高真空となると）発生量が激しくな
り、精錬炉の上部の合金添加孔・炉蓋・ダクト等に付着
して閉塞或いは種々の設備・操業トラブルを引き起こし
生産性を阻害する。また真空度を高くして且つ吹酸速度
を大きくすると、急激な脱炭反応が進行して、発生した
ＣＯガスによって溶鋼湯面近傍から大量の地金を一気に
吹上げる現象、即ち突沸を引き起こす。これも大きな設
備トラブルとなり生産性を悪化させる。When refining molten steel by using gaseous oxygen under vacuum, C produced by decarburization reaction
O gas blows metal and splash from the surface of molten steel toward the top of the vacuum refining furnace. The higher the degree of vacuum (higher vacuum), the more the amount generated, and the adhesion to the alloy addition holes, furnace lids, ducts, etc. at the top of the smelting furnace, causing blockage or causing various equipment / operation troubles and increasing productivity. Inhibit. Further, when the degree of vacuum is increased and the blowing acid velocity is increased, a rapid decarburization reaction proceeds, causing a phenomenon in which a large amount of metal is blown from the vicinity of the molten steel surface at once by the generated CO gas, that is, bumping. This also causes a big equipment trouble and deteriorates productivity.
【０００５】この様に、真空下での炭素含有溶鋼を吹酸
脱炭することは、極めて注意を要する操業である。その
ポイントは、溶鋼中の炭素濃度に応じて、真空度・吹酸
速度を制御することである。このうち吹酸速度について
は、酸素ガスの流量調節弁によりある程度制御可能であ
るが、真空度については充分な制御方法が確立されてい
ない。As described above, decarburization of molten steel containing carbon under vacuum is a very sensitive operation. The point is to control the degree of vacuum and the blowing acid velocity according to the carbon concentration in the molten steel. Of these, the blowing acid velocity can be controlled to some extent by an oxygen gas flow rate control valve, but a sufficient control method for the degree of vacuum has not been established.
【０００６】前記の従来技術の内、エジェクターを使用
する場合、多段のエジェクターを順次起動・停止する方
法は、エジェクター単体の能力範囲が広いため真空度を
きめ細かく制御することは不可能である。また、特開平
１０−１７１６号公報に見られる様に、排気装置を稼動
させながら外部からガスをリークさせる（例えば窒素を
使用する）方法は、ある程度の真空度の制御は可能であ
るが、ガスコストが高くなる欠点がある。ガスコスト削
減の方策として窒素の代替として空気を使用する方法が
ある。しかし、真空度制御そのものは可能であるが、吸
引する排ガスは高濃度のＣＯガスを含有しているため、
助燃ガスである酸素を含有する空気を混入した場合、燃
焼・爆発の危険性があり、実機への採用は極めて危険で
ある。更に、外部からガスをリークさせると、排気装置
の負荷が増え、例えば真空ポンプの使用電力は増大する
ため省エネルギーの観点からも好ましくない。また、同
文献で実施されているエジェクターへの蒸気供給量を制
御する方法は、エジェクターの排気特性の最適蒸気流量
は固有のものであるため、これを増減することはエジェ
クターそのものの排気性能を著しく低下せしめることに
なる。と同時に、僅かな蒸気流量変動がエジェクター性
能に敏感に影響し過ぎるため、精錬炉内圧力をきめ細か
に制御することも難しくなる。When the ejector is used among the above-mentioned prior arts, the method of sequentially starting and stopping the multistage ejector cannot control the degree of vacuum finely because the ejector alone has a wide capacity range. Further, as disclosed in Japanese Patent Application Laid-Open No. 10-1716, the method of leaking gas from the outside (using nitrogen, for example) while operating the exhaust device can control the degree of vacuum to some extent. There is a drawback that the cost is high. One way to reduce gas costs is to use air as a substitute for nitrogen. However, although the degree of vacuum control itself is possible, since the exhaust gas to be sucked contains high-concentration CO gas,
If air containing oxygen as a supporting gas is mixed, there is a risk of combustion and explosion, and it is extremely dangerous to use it in actual equipment. Further, if gas is leaked from the outside, the load on the exhaust device increases, and the power consumption of, for example, a vacuum pump increases, which is not preferable from the viewpoint of energy saving. Further, in the method of controlling the steam supply amount to the ejector implemented in the same document, the optimum steam flow rate of the exhaust characteristic of the ejector is peculiar, so increasing or decreasing this significantly increases the exhaust performance of the ejector itself. It will be lowered. At the same time, even a slight change in the flow rate of steam sensitively affects the ejector performance, and it is difficult to finely control the pressure in the refining furnace.
【０００７】一方、水封式真空ポンプを使用する方法
は、現在ポンプ単独での真空度の制御に用いられている
が、エジェクターとの併用はなく、単独では高真空にす
るには能力不足であり、真空度をきめ細かく制御するこ
とは不可能である。On the other hand, the method of using a water-sealed vacuum pump is currently used to control the degree of vacuum of the pump alone, but it is not used in combination with an ejector, and is insufficient in capacity to achieve a high vacuum by itself. Yes, it is impossible to finely control the degree of vacuum.
【０００８】[0008]
【課題を解決するための手段】本発明は、真空精錬炉で
溶湯を吹酸脱炭精錬する場合、炉内或いはダクト内の真
空度を制御可能な真空排気設備における真空度制御方法
及びそのための装置を提供するものである。DISCLOSURE OF THE INVENTION The present invention provides a method for controlling the degree of vacuum in a vacuum exhaust facility capable of controlling the degree of vacuum in a furnace or a duct when the molten metal is subjected to blown acid decarburization refining in a vacuum refining furnace. A device is provided.
【０００９】その要旨は以下の通りである。
（１）真空精錬設備のエジェクター式真空排気装置及び
水封式真空ポンプを同時に有する真空精錬炉で、溶湯を
真空精錬するに際し、水封式真空ポンプから排気された
排ガスの一部を真空度制御用圧力調整弁の弁開度を調整
して、水封式真空ポンプの排ガス流路上流側に戻し、真
空精錬炉内を８〜５３kPaの真空度に制御することを特
徴とする真空排気設備における真空度制御方法。
（２）エジェクター式真空排気装置及び水封式真空ポン
プのある真空排気設備側と排ガス冷却機及び集塵機のあ
る真空精錬炉側との間に真空弁を設け、真空精錬の処理
開始前に、真空弁を閉めた状態で、予め真空排気設備側
を８〜２７kPaの真空度にし、処理開始と同時に真空弁
を開き、真空精錬炉側の真空度を向上させることを特徴
とする（１）記載の真空度制御方法。
（３）合金・副材を炉内に添加する際に、真空度制御用
圧力調整弁の弁開度を調整し、排ガス流量の1０％以下
を水封式真空ポンプの上流側に戻すことで、速やかに真
空精錬炉内の真空度を向上せしめることを特徴とする
（１）又は（２）記載の真空度制御方法。
（４）炉内真空引き開始後に真空精錬炉内に不活性ガ
ス、窒素あるいはそれらの混合ガスを吹込み、排ガス中
の酸素濃度を７vol％以下とした後、精錬用酸素含有ガ
スを真空精錬炉内に吹込むことを特徴とする（１）〜
（３）のいずれか１項記載の真空度制御方法。
（５）真空精錬炉、排ガス冷却機、集塵機、真空弁、単
独あるいは複数段のエジェクタ−式真空排気装置、水封
式真空ポンプが順次配列され、かつ水封式真空ポンプか
ら排気された排ガスの一部を水封式真空ポンプの上流側
に戻す真空制御用圧力調節弁を有することを特徴とする
真空排気設備列。The gist is as follows. (1) In a vacuum refining furnace having an ejector-type vacuum exhaust device of a vacuum refining facility and a water-sealing vacuum pump at the same time, when vacuum-refining the molten metal, a part of exhaust gas exhausted from the water-sealing vacuum pump is controlled in vacuum degree. In the vacuum exhaust equipment, which is characterized in that the valve opening of the pressure adjusting valve is adjusted and returned to the upstream side of the exhaust gas passage of the water-sealed vacuum pump to control the vacuum degree in the vacuum refining furnace to a vacuum degree of 8 to 53 kPa. Vacuum control method. (2) A vacuum valve is provided between the vacuum exhaust equipment side having an ejector type vacuum exhaust device and a water-sealed vacuum pump and the vacuum refining furnace side having an exhaust gas cooler and a dust collector, and a vacuum is provided before the start of the vacuum refining process. With the valve closed, the vacuum exhaust equipment side is preliminarily set to a vacuum degree of 8 to 27 kPa, the vacuum valve is opened at the same time as the treatment is started, and the vacuum degree on the vacuum refining furnace side is improved (1). Vacuum control method. (3) By adjusting the valve opening of the pressure control valve for controlling the degree of vacuum when adding alloys and auxiliary materials into the furnace, and returning 10% or less of the exhaust gas flow rate to the upstream side of the water-sealed vacuum pump. The method for controlling the degree of vacuum according to (1) or (2), characterized in that the degree of vacuum in the vacuum refining furnace is promptly improved. (4) After starting the evacuation of the furnace, injecting an inert gas, nitrogen or a mixed gas thereof into the vacuum refining furnace to reduce the oxygen concentration in the exhaust gas to 7 vol% or less, and then refining the oxygen-containing gas for refining in the vacuum refining furnace. It is characterized by blowing in (1) ~
The vacuum control method according to any one of (3). (5) A vacuum refining furnace, an exhaust gas cooler, a dust collector, a vacuum valve, a single or multiple-stage ejector-type vacuum exhaust device, and a water-sealed vacuum pump are sequentially arranged, and exhaust gas exhausted from the water-sealed vacuum pump is A vacuum evacuation equipment row having a pressure control valve for vacuum control, which returns a part of the water-sealed vacuum pump to the upstream side.
【００１０】[0010]
【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。実施例の排ガス処理設備の概念図を図１に示す。
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、それに接続する排ガス冷却機５で冷却される。その
後ダクト３を通り集塵機６にて除塵され、多段エジェク
ター式真空排気装置７を通り、更に水封式真空ポンプ８
にて吸引され、大気放散される。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to the drawings. The conceptual diagram of the exhaust gas treatment equipment of the example is shown in FIG.
The exhaust gas 4 generated in the vacuum refining furnace 1 passes through the water cooling duct 2 and is cooled by the exhaust gas cooler 5 connected thereto. After that, the dust is removed by the dust collector 6 through the duct 3, passes through the multistage ejector type vacuum evacuation device 7, and then the water seal type vacuum pump 8
Is sucked in and released into the atmosphere.
【００１１】ここで、炉内真空度計１０、排ガス冷却機
後の真空度計１１、集塵機後真空度計１２、多段エジェ
クタ−式真空排気装置後の真空度計１３の何れかの真空
度を測定しつつ、圧力信号を制御装置１７に取込み、真
空度制御用圧力調整弁９の弁開度を調整しながら真空ポ
ンプ８の前面に排ガスの一部を戻す。これにより、真空
精錬炉内或いはダクト内を所定の目標真空度に制御する
ことが可能となる。真空度制御にあたり、どの真空度計
の信号を使用するかは精錬のステージによって自由に選
択可能である。Here, any one of the vacuum degree gauge 10 in the furnace, the vacuum gauge 11 after the exhaust gas cooler, the vacuum gauge 12 after the dust collector, and the vacuum gauge 13 after the multistage ejector type vacuum exhaust device is set. While measuring, the pressure signal is taken into the control device 17, and a part of the exhaust gas is returned to the front surface of the vacuum pump 8 while adjusting the valve opening of the vacuum degree control pressure adjusting valve 9. As a result, it is possible to control the inside of the vacuum refining furnace or the inside of the duct to a predetermined target degree of vacuum. Which vacuum gauge signal is used to control the degree of vacuum can be freely selected depending on the stage of refining.
【００１２】制御する真空度のレベルは、真空精錬炉か
らの地金の吹上げ量及び溶鋼中のクロムの酸化量によ
る。一般的に、真空度が良くなると（圧力値が低くなる
と）溶鋼中の炭素が優先的に酸化されてクロムの酸化量
は減少する。しかし、真空精錬炉から吹上げられる地金
・スプラッシュ量は増大する。即ち、クロム酸化ロス低
減からは、真空度を良くした方がよいが、地金・スプラ
ッシュ量低減からは真空度を下げた方が良いため、この
両者を考慮すると制御する真空度には最適な範囲が存在
する。また、この溶鋼中クロムの酸化量及び地金・スプ
ラッシュの吹上げ量は溶鋼中炭素量にも依存する。The level of vacuum to be controlled depends on the amount of the metal blown up from the vacuum refining furnace and the amount of oxidation of chromium in the molten steel. Generally, when the degree of vacuum is improved (the pressure value is lowered), carbon in the molten steel is preferentially oxidized, and the oxidation amount of chromium is reduced. However, the amount of metal and splash blown up from the vacuum refining furnace increases. That is, it is better to improve the degree of vacuum in order to reduce chromium oxidation loss, but it is better to lower the degree of vacuum in order to reduce the amount of metal / splash. Range exists. Further, the oxidation amount of chromium in the molten steel and the blowing amount of the metal / splash also depend on the carbon amount in the molten steel.
【００１３】よって、これらの定量的な例を図２に示し
た。図２は、精錬炉内真空度と真空精錬炉からの地金吹
上げ量（指数）及び溶鋼中クロムの酸化量（指数）との
関係を示す図である。本図より、クロム酸低減及び地金
吹上げ防止の観点から制御すべき真空度は８〜５３kPa
の範囲である。図２より、溶鋼を真空処理する場合、真
空度は８〜５３kPaに制御すること必要がある。本範囲
は、請求項１に記述した真空度制御範囲の根拠となって
いる。Therefore, these quantitative examples are shown in FIG. FIG. 2 is a diagram showing the relationship between the degree of vacuum in the refining furnace, the amount of metal injection (index) from the vacuum refining furnace, and the amount of oxidation of chromium in molten steel (index). From this figure, the degree of vacuum to be controlled is 8 to 53 kPa from the viewpoint of reducing chromic acid and preventing metal blowing up.
Is the range. From FIG. 2, when vacuum processing molten steel, it is necessary to control the degree of vacuum to 8 to 53 kPa. This range is the basis of the vacuum degree control range described in claim 1.
【００１４】次に、本装置の使用方法を図１及び図３の
使用例にもとづいて説明する。真空精錬の処理開始前
に、真空排気装置前面の真空弁１４を閉めておき、エジ
ェクター及び水封式真空ポンプを含む真空排気設備側と
排ガス冷却機或いは集塵機を含む真空精錬炉側とを真空
弁１４により区切る。ここで予め真空排気設備側内を真
空度計１３の信号を基に１３kPaを目標に真空度制御し
ておく。（これは操業上プレバキューム処理と呼ぶ）
真空ポンプは、真空度が６．７〜８kPa程度になると、
水の蒸発が激しくなりキャビテーションを起こすため、
前述の真空度を設定して真空度制御を行う。従来は約８
kPa以下となるとキャビテーション防止弁により、圧力
をリリーフして真空度を調整していたが、該防止弁の開
閉頻度の増加により弁体のリークが問題となっていた。
しかし、本発明により該防止弁の開閉頻度は激減し、弁
体からのリークは無くなった。よって、真空度制御は８
kPa以上の範囲となる。Next, a method of using this apparatus will be described based on the usage examples of FIGS. 1 and 3. Before the start of the vacuum refining process, the vacuum valve 14 on the front of the vacuum exhaust device is closed, and the vacuum exhaust equipment side including the ejector and the water-sealed vacuum pump and the vacuum refining furnace side including the exhaust gas cooler or the dust collector are vacuum valves. Divide by 14. Here, the degree of vacuum is controlled in advance on the side of the vacuum exhaust equipment on the basis of the signal from the vacuum gauge 13 with a target of 13 kPa. (This is called pre-vacuum treatment in operation.) When the vacuum degree of the vacuum pump becomes about 6.7 to 8 kPa,
Because water evaporation is intense and causes cavitation,
The degree of vacuum is set and the degree of vacuum is controlled. Conventionally about 8
When the pressure was lower than kPa, the pressure was relieved by the cavitation prevention valve to adjust the degree of vacuum, but the increase in the frequency of opening and closing the prevention valve caused a problem of valve leakage.
However, according to the present invention, the frequency of opening and closing the prevention valve is drastically reduced, and the leak from the valve body is eliminated. Therefore, the degree of vacuum control is 8
It is in the range of kPa or more.
【００１５】また、この後大気圧の精錬炉側と均圧化し
た際真空度の低下を抑制するために、プレバキュームの
真空度は、できるだけ高真空であることが好ましい。よ
って、プレバキュームの真空度の制御範囲は、真空度制
御用圧力調整弁９の制御性を考慮して８〜２７kPaとし
た。これは請求項２に記述した真空度制御範囲の根拠と
なっている。Further, in order to suppress a decrease in the degree of vacuum when the pressure is thereafter equalized with the refining furnace side at atmospheric pressure, the degree of vacuum of the prevacuum is preferably as high as possible. Therefore, the control range of the vacuum degree of the prevacuum is set to 8 to 27 kPa in consideration of the controllability of the vacuum degree control pressure adjusting valve 9. This is the basis of the vacuum control range described in claim 2.
【００１６】精錬炉側の処理準備完了後、炉内真空度引
きを開始する。処理開始と同時に真空弁１４を開き、真
空排気設備側と真空精錬炉側とを同圧真空とし、引き続
いて真空排気装置により経路全体を速やかに高真空とす
る。真空処理を開始して経路全体を真空とする場合、真
空度制御用圧力制御弁９を閉じて速やかに高真空化した
い。しかし、真空弁１４を開く前は真空度制御により圧
力調整弁９は全開に近い状態となっており、例えば、炉
内真空度計１０の信号によるフィードバック制御に基づ
く真空度制御では圧力制御弁の弁開度を急速に閉じるこ
とは難しい。そこで、真空開始の信号と同時に前記圧力
調整弁の弁開度を強制的に２０％以下好ましくは全閉に
固定して、真空ポンプ後の排ガスの戻りを無くすことに
より、速やかに真空度を向上せしめることが可能とな
る。図３の(ａ)の真空度向上効果が得られる。ここで、
圧力調整弁９の一般的な弁特性から、弁開度が２０％以
下となると殆ど全閉に近くなり流体を遮断する特性をも
つ。After the preparation for the treatment on the refining furnace side is completed, the vacuuming in the furnace is started. Simultaneously with the start of the processing, the vacuum valve 14 is opened, the vacuum exhaust equipment side and the vacuum refining furnace side are brought to the same pressure vacuum, and then the entire path is quickly brought to a high vacuum by the vacuum exhaust device. When the vacuum processing is started and the entire path is evacuated, it is desired to close the pressure control valve 9 for controlling the degree of vacuum to quickly attain a high vacuum. However, before the vacuum valve 14 is opened, the pressure control valve 9 is in a state of being almost fully opened by the vacuum degree control. For example, in the vacuum degree control based on the feedback control by the signal of the furnace vacuum gauge 10, It is difficult to close the valve opening rapidly. Therefore, the degree of vacuum is promptly improved by forcibly fixing the valve opening degree of the pressure control valve to 20% or less, preferably fully closed at the same time as the vacuum start signal to eliminate the return of exhaust gas after the vacuum pump. It is possible to blame. The vacuum degree improving effect of FIG. 3A is obtained. here,
From the general valve characteristics of the pressure regulating valve 9, when the valve opening degree is 20% or less, the pressure adjusting valve 9 has a characteristic of being almost completely closed and shutting off the fluid.
【００１７】そこで圧力調整弁を調整し、排ガス流量の
１０％以下の流量を水封式真空ポンプの上流側に戻すこ
とで速やかに真空精練炉内の真空度を向上せしめるのだ
が、戻す排ガス流量が１０％を超えると真空度が速やか
に向上しないので１０％以下とした。これは請求項３に
記述した上流側に戻す排ガス流量１０％の根拠となって
いる。Therefore, by adjusting the pressure adjusting valve and returning the flow rate of 10% or less of the exhaust gas flow rate to the upstream side of the water-sealed vacuum pump, the degree of vacuum in the vacuum refining furnace can be promptly improved. Is more than 10%, the degree of vacuum does not improve promptly, so it was made 10% or less. This is the basis for the exhaust gas flow rate returning to the upstream side of 10% described in claim 3.
【００１８】処理時間を短縮するために、真空開始後出
来るだけ速やかに吹酸脱炭を開始したい。しかし、吹酸
と同時に大量のＣＯガスが発生するが、真空精錬炉内或
いは真空ダクト内に酸素が残留していると、生成したＣ
Ｏガスと反応し燃焼・爆発する危険がある。そこで真空
精錬炉及び真空ダクト内の酸素濃度を爆発限界以下に速
やかに低減させる必要がある。その方法として、真空精
錬炉内に酸素を含有しない大量の不活性ガスや窒素或い
はそれらの混合ガスを吹込み、酸素を稀釈することが有
効である。但し、真空度を向上させた状態で稀釈ガス吹
込みを行わないと稀釈ガスが大量に必要となる。ＣＯの
爆発限界となる排ガス中の酸素濃度は発明者らの試験結
果により７vol％超〜９vol％以下であることが判明し
た。よって、排ガス中の酸素濃度を７vol％以下とす
る。これは請求項４に記述した排ガス中の酸素濃度を速
やかに７vol％以下とすることの根拠となっている。図
３の（ｂ）は、排ガス中ＣＯガス濃度が７vol％以下と
なり、吹酸脱炭を開始したタイミングを示す。In order to reduce the processing time, it is desired to start the decarburization of propellant acid as soon as possible after the start of vacuum. However, although a large amount of CO gas is generated at the same time as the blowing acid, if the oxygen remains in the vacuum refining furnace or the vacuum duct, the generated C
There is a risk of combustion and explosion due to reaction with O gas. Therefore, it is necessary to quickly reduce the oxygen concentration in the vacuum refining furnace and the vacuum duct to below the explosion limit. As a method, it is effective to blow a large amount of oxygen-free inert gas, nitrogen, or a mixed gas thereof into the vacuum refining furnace to dilute the oxygen. However, a large amount of diluting gas is required unless the diluting gas is blown in with the degree of vacuum improved. The oxygen concentration in the exhaust gas, which is the explosion limit of CO, was found to be more than 7 vol% to 9 vol% or less according to the test results of the inventors. Therefore, the oxygen concentration in the exhaust gas is set to 7 vol% or less. This is the basis for promptly reducing the oxygen concentration in the exhaust gas to 7 vol% or less as described in claim 4. FIG. 3B shows the timing at which the concentration of CO gas in the exhaust gas becomes 7 vol% or less and the decarburization of blown acid is started.
【００１９】真空精錬炉で溶湯を吹酸脱炭する場合、前
述した様に生成するＣＯガスにより、溶湯からの地金・
スプラッシュの激しい吹上げ、或いは急激に地金が吹上
げる突沸を引き起こす危険性がある。そこで吹酸開始後
は速やかに真空度を低下させ、操業上前記トラブルを回
避可能な真空度に制御する必要がある。このため、真空
度制御用圧力制御弁９を開けて排ガスを真空ポンプ後面
から前面に戻して真空度を低下させたいが、吹酸開始前
は真空度制御により真空度制御用圧力調整弁９は全閉に
近い状態となっており、自動モードでは真空度制御用圧
力制御弁９の弁開度を急速に開けることは難しい。そこ
で、吹酸開始の信号と同時に真空度制御用圧力調整弁９
の弁開度を強制的に８０％以上に固定して、真空ポンプ
後の排ガスの戻りを調整弁の能力上限まで増やすことに
より、速やかに真空度を低下せしめることが可能とな
る。圧力調整弁の一般的な弁特性から弁開度を８０％以
上にすればほぼ全開に近い流量が流れるため、ここでの
弁開度は８０％以上とした。When the molten metal is decarburized in a vacuum refining furnace, the CO gas generated as described above causes the metal
There is a risk of violent splashing or sudden bumping of the metal. Therefore, it is necessary to reduce the degree of vacuum promptly after the start of blowing acid and control the degree of vacuum so that the above troubles can be avoided in operation. Therefore, it is desired to open the pressure control valve 9 for controlling the degree of vacuum to return the exhaust gas from the rear surface to the front of the vacuum pump to reduce the degree of vacuum. Since the state is close to the fully closed state, it is difficult to open the valve opening degree of the vacuum degree control pressure control valve 9 rapidly in the automatic mode. Therefore, at the same time as the signal to start the blowing acid, the pressure control valve 9 for controlling the degree of vacuum is
By forcibly fixing the valve opening degree to 80% or more and increasing the return of the exhaust gas after the vacuum pump to the upper limit of the capacity of the adjusting valve, the degree of vacuum can be promptly lowered. From the general valve characteristics of the pressure regulating valve, if the valve opening is set to 80% or more, a flow rate close to full opening flows, so the valve opening here is set to 80% or more.
【００２０】図３の実施例では、（ｃ）に示す様に精錬
炉内へ吹酸開始後５０秒間前記圧力調整弁の弁開度を１
００％に固定することにより、一旦２０kPaに向上した
真空度を速やかに４０kPaに戻して制御することが出来
た。この制御する真空度は、溶湯中炭素濃度及び吹酸速
度によって異なり、発明者らの研究では８〜５３kPaの
範囲が適正と判明した。この真空度の根拠は前述した様
に図２に示される。また、吹酸開始後に真空度制御用圧
力調整弁９を８０％以上に固定する時間は、制御する真
空度及び真空精錬炉〜真空排気装置に至る真空とする内
容積等により決まり、発明者らの経験より３０秒〜１２
０秒が最適な範囲と判明した。よって前述した精錬炉内
へ吹酸開始後、この所定の時間内は前記真空度制御用圧
力調整弁の弁開度を８０％以上に固定することにより、
速やかに真空度を８〜５３kPaの真空度に制御すること
ができる。In the embodiment of FIG. 3, as shown in (c), the valve opening of the pressure adjusting valve is set to 1 for 50 seconds after the start of blowing acid into the refining furnace.
By fixing it to 00%, the degree of vacuum once improved to 20 kPa could be quickly returned to 40 kPa and controlled. The degree of vacuum to be controlled depends on the carbon concentration in the molten metal and the velocity of the propellant acid, and the inventors' studies have found that the range of 8 to 53 kPa is appropriate. The basis of this degree of vacuum is shown in FIG. 2 as described above. Further, the time for fixing the pressure control valve 9 for controlling the degree of vacuum after the start of spouting acid to 80% or more is determined by the degree of vacuum to be controlled and the internal volume of the vacuum from the vacuum refining furnace to the vacuum exhaust device. 30 seconds to 12
0 seconds was found to be the optimum range. Therefore, after the start of blowing acid into the refining furnace, by fixing the valve opening degree of the vacuum degree control pressure adjusting valve to 80% or more within this predetermined time,
The degree of vacuum can be quickly controlled to a degree of vacuum of 8 to 53 kPa.
【００２１】前述の様に溶湯を真空吹酸脱炭する場合、
地金・スプラッシュの吹上げ及び急激な突沸を回避する
ため真空度をある程度悪くして（圧力を上げて）吹酸脱
炭する必要がある。しかし、これは溶湯中炭素濃度や吹
酸速度によって適正な真空度があり、炭素濃度が低いほ
ど或いは吹酸速度が低いほど地金の吹上げ・突沸の危険
性は回避される。一方、溶湯中炭素濃度の低下により鉄
及びクロム等の酸化ロスが増えるため、冶金的にも真空
度は出来るだけ高くすることがこれらの酸化ロスの抑制
にとって好ましい。そこで、溶湯の炭素濃度が高い場合
は真空度を低くしておき、炭素濃度が低くなると真空度
を相対的に高くするような真空度制御を行い、地金の吹
き上げ・突沸回避と鉄・クロムの酸化ロス低減を同時に
満足できることができた。When the molten metal is decarburized by vacuum blowing acid as described above,
In order to avoid blowing up of metal and splash and sudden bumping, it is necessary to reduce the degree of vacuum to some degree (increase the pressure) to perform decarburization of fuming acid. However, this has an appropriate degree of vacuum depending on the carbon concentration in the molten metal and the blowing acid velocity, and the lower the carbon concentration or the lower the blowing acid velocity, the more the risk of blowing up and bumping of the metal is avoided. On the other hand, since the oxidation loss of iron, chromium, etc. increases due to the decrease in the carbon concentration in the molten metal, it is preferable to metallurgically increase the degree of vacuum as much as possible in order to suppress these oxidation losses. Therefore, when the molten metal has a high carbon concentration, the degree of vacuum is kept low, and when the carbon concentration is low, the degree of vacuum is controlled to be relatively high to prevent the metal from blowing up and avoiding bumping and iron / chromium. It was possible to satisfy the above-mentioned reduction of oxidation loss at the same time.
【００２２】本発明の実施例としては、溶湯中炭素濃度
が０．６０質量％〜０．４０質量％では、真空度４０kP
a、溶湯中炭素濃度が０．４０質量％〜０．２５質量％
では、真空度２７kPa、溶湯中炭素濃度が０．２５質量
％〜０．２０質量％では、真空度１３kPaで制御を実施
した。これらの真空度レベルは、精錬する鋼種、吹酸速
度及び精錬炉のタイプ・状況等の操業条件により異な
り、ローカルな条件に適合する様に決定する必要があ
る。また吹酸速度は、制御する真空度と同様に、溶鋼中
炭素濃度の減少に合わせて順次低減することも操業上・
冶金的に有効であり、本発明はこれを踏まえた上での真
空度制御を範囲としている。溶湯の炭素濃度の低下によ
って順次真空度を高真空側に制御することの根拠となっ
ている。As an example of the present invention, when the carbon concentration in the molten metal is 0.60% by mass to 0.40% by mass, the degree of vacuum is 40 kP.
a, Carbon concentration in molten metal is 0.40 mass% to 0.25 mass%
Then, when the degree of vacuum was 27 kPa and the carbon concentration in the molten metal was 0.25% by mass to 0.20% by mass, the control was performed at a degree of vacuum of 13 kPa. These vacuum levels differ depending on the operating conditions such as the type of steel to be refined, the blowing acid velocity, and the type and condition of the refining furnace, and it is necessary to decide so as to meet local conditions. In addition, as with the vacuum degree to be controlled, it is also possible to reduce the sprayed acid rate in sequence as the carbon concentration in the molten steel decreases.
It is metallurgically effective, and the scope of the present invention is vacuum degree control based on this. This is the basis for controlling the degree of vacuum to the high vacuum side sequentially by decreasing the carbon concentration of the molten metal.
【００２３】前記真空度制御において、溶鋼中炭素濃度
の低下に伴い制御する真空度を高真空に順次切り替える
方法において、速やかな高真空化への切り替えが望まし
い。しかし、真空度の切り替え直前は、経験的に排ガス
流量の低下により圧力調整弁９は全開に近い状態となっ
ており、自動モードでは高真空化に切り替え直後に圧力
制御弁の弁開度を急速に閉じることは難しい。そこで、
高真空化への切り替え信号と同時に前記圧力調整弁の弁
開度を強制的に０％〜２０％に固定して６０秒間保持し
た。図３（ｄ）にこの結果を示す。これにより、真空ポ
ンプ後の排ガスの戻りが無くなり、速やかに真空度を向
上せしめることが可能となった。但しここで「０％」と
は圧力制御弁を完全に閉めていることを意味する。圧力
調整弁９の一般的な弁特性から、弁開度が２０％以下と
なると殆ど全閉に近くなり流体を遮断する特性をもつた
め、弁開度を２０％以下とした。また、高真空側へ真空
度を切替える場合に真空度制御用圧力調整弁９の弁開度
を２０％以下に固定する時間は、制御する真空度及び真
空精錬炉〜真空排気装置に至る真空とする内容積等によ
り決まり、発明者らの経験より３０秒〜１２０秒が最適
な範囲と判明した。In the above-mentioned vacuum degree control, in the method of sequentially switching the vacuum degree to be controlled to a high vacuum as the carbon concentration in molten steel decreases, it is desirable to quickly switch to a high vacuum. However, empirically, immediately before the switching of the vacuum degree, the pressure adjusting valve 9 is in a state of being almost fully opened due to the decrease of the exhaust gas flow rate, and in the automatic mode, the valve opening of the pressure control valve is rapidly changed immediately after switching to the high vacuum. Difficult to close to. Therefore,
Simultaneously with the signal for switching to high vacuum, the valve opening of the pressure regulating valve was forcibly fixed to 0% to 20% and held for 60 seconds. This result is shown in FIG. As a result, the exhaust gas does not return after the vacuum pump, and the degree of vacuum can be promptly improved. However, "0%" here means that the pressure control valve is completely closed. From the general valve characteristics of the pressure regulating valve 9, the valve opening degree is set to 20% or less because the valve opening degree is almost fully closed when the valve opening degree is 20% or less and shuts off the fluid. Further, when switching the vacuum degree to the high vacuum side, the time for fixing the valve opening degree of the vacuum degree control pressure adjusting valve 9 to 20% or less depends on the vacuum degree to be controlled and the vacuum from the vacuum refining furnace to the vacuum exhaust device. The optimum range is determined by the inventors' experience, and the optimum range is from 30 seconds to 120 seconds.
【００２４】真空度制御中、真空精錬炉に副材・合金鉄
等を添加することがある。この場合、添加される副材・
合金鉄等は予め中間ホッパーに貯留され、この中間ホッ
パーを炉内とほぼ同等の真空度とした後炉内に添加され
る。従って、添加時の排ガス流量への影響は殆ど無い筈
であるが、例えば添加される副材に生石灰が含まれる
と、生石灰中の残留ＣＯ2等のガス成分が発生したり、
その他合金・副材等により炉内での急激なガス発生反応
を引き起こすことがある。これらの発生したガスは排ガ
ス流量を急激に増加させるため、前記圧力調整弁の弁開
度が追従しなくなり、真空度の急な悪化（圧力の上昇）
をもたらす。そこで合金・副材等の炉内添加後４０秒間
は、前記圧力調整弁の弁開度を０％に固定して、積極的
に排ガスを吸引することにより、図３（ｅ）に示す様に
排ガス流量の急激な増加による真空度の悪化を抑制でき
た。但し、ここで「０％」とは圧力制御弁を完全に閉め
ていることを意味する。圧力調整弁９の一般的な弁特性
から、弁開度が２０％以下となると殆ど全閉に近くなり
流体を遮断する特性をもつ。そこで圧力調整弁を調整
し、排ガス流量の１０％以下の流量を水封式真空ポンプ
の上流側に戻すことで速やかに真空精練炉内をの真空度
を向上せしめるのだが、戻す排ガス流量が１０％を超え
ると真空度が速やかに向上しないので１０％以下とし
た。これは請求項３に記述した上流側に戻す排ガス流量
１０％の根拠となっている。During the control of the degree of vacuum, auxiliary materials, ferroalloys, etc. may be added to the vacuum refining furnace. In this case, the additional material
The ferroalloy and the like are stored in the intermediate hopper in advance, and the intermediate hopper is added to the inside of the furnace after the degree of vacuum is almost the same as the inside of the furnace. Therefore, there should be almost no influence on the exhaust gas flow rate at the time of addition, but when, for example, quicklime is contained in the auxiliary material to be added, gas components such as residual CO 2 in quicklime are generated,
Other alloys / auxiliary materials may cause a rapid gas generation reaction in the furnace. Since the generated gas sharply increases the exhaust gas flow rate, the valve opening of the pressure regulating valve does not follow up, and the vacuum degree suddenly deteriorates (pressure rise).
Bring Therefore, for 40 seconds after the addition of alloys and auxiliary materials in the furnace, the valve opening of the pressure regulating valve is fixed at 0% and the exhaust gas is positively sucked, as shown in Fig. 3 (e). It was possible to suppress the deterioration of the degree of vacuum due to the rapid increase in the exhaust gas flow rate. However, "0%" here means that the pressure control valve is completely closed. From the general valve characteristics of the pressure regulating valve 9, when the valve opening degree is 20% or less, the pressure adjusting valve 9 has a characteristic of being almost completely closed and shutting off the fluid. Therefore, by adjusting the pressure control valve and returning a flow rate of 10% or less of the exhaust gas flow rate to the upstream side of the water-sealed vacuum pump, the degree of vacuum in the vacuum scouring furnace can be quickly improved, but the exhaust gas flow rate to be returned is 10%. If it exceeds 10%, the degree of vacuum does not improve promptly, so it was made 10% or less. This is the basis for the exhaust gas flow rate returning to the upstream side of 10% described in claim 3.
【００２５】また、合金・副材等の炉内添加後真空度制
御用圧力調整弁９の弁開度を調整し、排ガス流量１０％
を戻す時間は、制御する真空度、合金添加ホッパー容
量、ホッパー内真空度、及び真空精錬炉〜真空排気装置
に至る真空とする内容積等により決まり、発明者らの経
験より３０秒〜９０秒が最適な範囲と判明した。Further, after the addition of alloys and auxiliary materials in the furnace, the valve opening of the pressure adjusting valve 9 for controlling the degree of vacuum is adjusted so that the exhaust gas flow rate is 10%.
The time for returning is determined by the degree of vacuum to be controlled, the capacity of the alloy-added hopper, the degree of vacuum in the hopper, the internal volume of the vacuum from the vacuum refining furnace to the vacuum exhaust device, etc. Was found to be the optimum range.
【００２６】真空精錬炉に添加される副材・合金鉄等は
通常溶鋼に対して冷却効果をもつため溶鋼温度が低下す
る。また間欠的な添加のため、ある程度まとまった添加
量となり、溶鋼温度は一時的に大きく冷却される。溶鋼
温度が低下すると冶金的に吹酸脱炭の脱炭酸素効率が悪
化し、鉄・クロム等の酸化ロスが大きくなる。これを抑
制するためには、温度が一時的に低下したタイミングで
真空度を向上させて、脱炭酸素効率を上昇させることが
有効である。そこで、真空精錬炉に副材・合金鉄等を添
加後、前述した排ガス流量の一時的な増加が沈静した後
も引き続き１２０秒間、前記圧力調整弁の弁開度を０％
に固定して、真空度をより高真空に保持した。これによ
り、副材・合金添加による溶湯温度の低下による脱炭反
応効率低下を抑制が可能となった。但し、ここで「０
％」とは圧力制御弁を完全に閉めていることを意味す
る。圧力調整弁９の一般的な弁特性から、弁開度が２０
％以下となると殆ど全閉に近くなり流体を遮断する特性
をもつため、真空度制御用圧力調整弁の弁開度を０〜２
０％以下とした。また、合金・副材等の炉内添加後真空
度制御用圧力調整弁９の弁開度を２０％以下に固定する
時間は、制御する真空度、合金添加量、溶鋼中炭素濃
度、溶鋼中［Ｃｒ］，［Ｎｉ］等の合金成分濃度、及び
真空精錬炉〜真空排気装置に至る真空とする内容積等に
より決まり、発明者らの経験より９０秒〜２４０秒が最
適な範囲と判明した。Since the auxiliary materials, ferroalloys, etc. added to the vacuum refining furnace usually have a cooling effect on the molten steel, the molten steel temperature is lowered. In addition, because of the intermittent addition, the addition amount becomes a certain amount, and the molten steel temperature is temporarily greatly cooled. When the temperature of molten steel decreases, the efficiency of decarburizing in decarburization of blown acid is metallurgically deteriorated, and the oxidation loss of iron, chromium, etc. increases. In order to suppress this, it is effective to improve the degree of vacuum and increase the decarbonation efficiency at the timing when the temperature is temporarily lowered. Therefore, after adding auxiliary materials, ferroalloys, etc. to the vacuum refining furnace, the valve opening degree of the pressure regulating valve is set to 0% for 120 seconds after the above-mentioned temporary increase in the exhaust gas flow rate has subsided.
The vacuum degree was maintained at a higher vacuum by fixing to a vacuum. As a result, it became possible to suppress the decrease in decarburization reaction efficiency due to the decrease in molten metal temperature due to the addition of auxiliary materials and alloys. However, here "0
"%" Means that the pressure control valve is completely closed. From the general valve characteristics of the pressure regulating valve 9, the valve opening is 20
%, The valve opening of the pressure control valve for controlling the degree of vacuum is 0 to 2 because it has a characteristic that it closes to full closure and shuts off the fluid.
It was set to 0% or less. Further, the time for fixing the valve opening of the pressure control valve 9 for controlling the degree of vacuum after adding alloys / auxiliary materials etc. in the furnace is controlled by the degree of vacuum, the amount of alloy addition, the carbon concentration in molten steel, and the in molten steel. 90 seconds to 240 seconds has been found to be the optimum range based on the experience of the inventors, which is determined by the concentration of alloy components such as [Cr] and [Ni] and the internal volume of the vacuum refining furnace to the vacuum exhaust device. .
【００２７】図１の実施例では、真空度制御の方法とし
て、真空ポンプから排出された排ガスの一部を真空ポン
プの排ガス入側に戻しているが、戻す場所はエジェクタ
ーの前段に戻しても良い。これは制御の目標とする真空
度のレベル及び各排気装置の特性に依存しており、各々
に応じて最適なプロセス構成とすることが肝要である。In the embodiment of FIG. 1, a part of the exhaust gas discharged from the vacuum pump is returned to the exhaust gas inlet side of the vacuum pump as a method for controlling the degree of vacuum, but the return location may be returned to the front stage of the ejector. good. This depends on the level of the degree of vacuum targeted for control and the characteristics of each exhaust device, and it is essential to set the optimum process configuration according to each.
【００２８】[0028]
【発明の効果】以上述べたように、溶湯を真空下で吹酸
脱炭精錬する場合、真空精錬炉内或いはダクト内の真空
度を制御可能とする真空排気装置及び制御方法を確立し
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。第１に、全体の真空処理時間の短縮が図
れ、生産性の向上及び真空精錬炉の耐火物寿命を向上さ
せることができた。第２に、真空吹酸精錬中の地金・ス
プラッシュの吹上げ、地金の突沸等を効果的に防止で
き、合金添加孔の閉塞防止・天蓋の地金付着防止・真空
排気ダクトの閉塞防止等が図れた。これにより、設備休
止時間が大幅に短縮され、メンテナンス費用の削減・操
業生産性の向上を達成できた。第３に、真空吹酸脱炭の
開始前における排ガス中酸素濃度制御を迅速に実施でき
たため、吹酸開始時の急激なＣＯ発生に対して排ガスの
爆発・燃焼等のトラブル無く安全に操業することが出来
た。第４に、真空度制御を適切に行うことにより、溶湯
中の鉄・クロムの酸化ロスを最小限に抑制でき、クロム
酸還元用フェロシリコンの原単位の低減、生石灰・ドロ
マイト等の副材原単位の減少、酸素原単位の低減及び真
空精錬炉の寿命延長に大きく貢献できた。第５に、真空
処理開始前の真空排気設備内のプレバキューム処理にお
いて、水封式真空ポンプのキャビテーション防止弁の寿
命を大きく延長させることができた。第６に、ステンレ
ス鋼の真空精錬の処理開始の溶鋼中炭素濃度を高くする
ことが出来、酸素と共に使用していた高価なＡｒを安価
な窒素に代替することが出来、精錬用ガスコストの大幅
な削減が可能となった。As described above, when the molten metal is subjected to blown acid decarburization refining under vacuum, a vacuum evacuation device and a control method capable of controlling the degree of vacuum in the vacuum refining furnace or in the duct have been established. The equipment and operational effects obtained by this are as follows. First, it was possible to shorten the overall vacuum processing time, improve productivity, and improve the refractory life of the vacuum refining furnace. Secondly, it is possible to effectively prevent blowing up of metal / splash and bumping of metal during vacuum blown acid refining, and to prevent clogging of alloy-added holes / prevention of adhesion of metal to canopy / vacuum exhaust duct. And so on. As a result, equipment downtime was significantly shortened, maintenance costs were reduced, and operational productivity was improved. Thirdly, because the oxygen concentration in the exhaust gas can be quickly controlled before the start of decarburization of vacuum blown acid, the system can operate safely without any trouble such as explosion or combustion of exhaust gas against the sudden generation of CO at the start of blown acid. I was able to do it. Fourth, by properly controlling the degree of vacuum, the oxidation loss of iron and chromium in the molten metal can be minimized, the unit consumption of ferrosilicon for reducing chromic acid is reduced, and the secondary materials such as quicklime and dolomite are reduced. It has contributed greatly to the reduction of the unit, the reduction of the oxygen consumption rate, and the extension of the life of the vacuum refining furnace. Fifthly, in the prevacuum treatment in the vacuum exhaust equipment before the start of the vacuum treatment, the life of the cavitation prevention valve of the water-sealed vacuum pump could be greatly extended. Sixth, it is possible to increase the carbon concentration in the molten steel at the start of the vacuum refining process for stainless steel, and to replace expensive Ar used with oxygen with cheap nitrogen, which greatly reduces the cost of refining gas. It has become possible to reduce.
【図１】真空精錬設備の排ガス処理装置を模式的に示す
図である。FIG. 1 is a diagram schematically showing an exhaust gas treatment device of a vacuum refining facility.
【図２】溶鋼中炭素濃度が０．２質量％以上の場合、精
錬炉内真空度と真空精錬炉からの地金吹上げ量（指数）
及び溶鋼中クロムの酸化量（指数）との関係を示す図で
ある。[Fig. 2] When the carbon concentration in molten steel is 0.2 mass% or more, the degree of vacuum in the refining furnace and the amount of metal injection from the vacuum refining furnace (index)
FIG. 3 is a diagram showing a relationship with the oxidation amount (index) of chromium in molten steel.
【図３】真空処理時間の推移と真空精錬炉内及び真空排
気装置内の真空度の変化を示す図である。FIG. 3 is a diagram showing changes in the vacuum processing time and changes in the degree of vacuum in the vacuum refining furnace and the vacuum exhaust device.
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．排ガス冷却機 ６．集塵機 ７．多段エジェクター式真空排気装置 ８．水封式真空ポンプ ９．真空度制御用圧力調整弁 １０．炉内用圧力発信器 １１．ガスクーラー後圧力発信器 １２．集塵器後圧力発信器 １３．真空排気装置内圧力発信器 １４．真空弁 １５．真空度調整時戻り排ガス １６．戻り排ガス用ダクト １７．圧力制御装置 1. Vacuum refining furnace 2. Exhaust gas water cooling duct 3. Exhaust gas duct (non-water cooling) 4. Exhaust gas 5. Exhaust gas cooler 6. Dust collector 7. Multi-stage ejector type vacuum exhaust device 8. Water-sealed vacuum pump 9. Pressure control valve for vacuum control 10. Pressure transmitter for furnace 11. Pressure transmitter after gas cooler 12. Pressure transmitter after dust collector 13. Pressure transmitter in vacuum exhaust device 14. Vacuum valve 15. Exhaust gas returned during vacuum adjustment 16. Return exhaust gas duct 17. Pressure control device
───────────────────────────────────────────────────── フロントページの続き (72)発明者 田中 智昭 山口県光市大字島田3434番地 新日本製鐵 株式会社光製鐵所内 (72)発明者 角 眞 福岡県北九州市戸畑区大字中原46−59 日 鐵プラント設計株式会社内 Ｆターム(参考） 4K013 FA04 FA12 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Tomoaki Tanaka No. 3434 Shimada, Hikari City, Yamaguchi Prefecture Nippon Steel Hikari Steel Works Co., Ltd. (72) Inventor Makoto Kaku 46-59 days Nakahara, Tobata-ku, Kitakyushu, Fukuoka Prefecture Inside the Iron Plant Design Co., Ltd. F-term (reference) 4K013 FA04 FA12
Claims (5)
装置及び水封式真空ポンプを同時に有する真空精錬炉
で、溶湯を真空精錬するに際し、水封式真空ポンプから
排気された排ガスの一部を真空度制御用圧力調整弁の弁
開度を調整して、水封式真空ポンプの排ガス流路上流側
に戻し、真空精錬炉内を８〜５３kPaの真空度に制御す
ることを特徴とする真空排気設備における真空度制御方
法。1. A vacuum refining furnace having an ejector-type vacuum exhaust device of a vacuum refining facility and a water-sealing vacuum pump at the same time, and a part of the exhaust gas exhausted from the water-sealing vacuum pump is vacuumed when the molten metal is vacuum-refined. The degree of pressure control valve opening is adjusted and returned to the upstream side of the exhaust gas flow path of the water-sealed vacuum pump to control the vacuum degree in the vacuum refining furnace to a vacuum degree of 8 to 53 kPa. Vacuum control method for equipment.
真空ポンプのある真空排気設備側と排ガス冷却機及び集
塵機のある真空精錬炉側との間に真空弁を設け、真空精
錬の処理開始前に、真空弁を閉めた状態で、予め真空排
気設備側を８〜２７kPaの真空度にし、処理開始と同時
に真空弁を開き、真空精錬炉側の真空度を向上させるこ
とを特徴とする請求項１記載の真空度制御方法。2. A vacuum valve is provided between a vacuum exhaust equipment side having an ejector type vacuum exhaust device and a water-sealed vacuum pump and a vacuum refining furnace side having an exhaust gas cooler and a dust collector, before starting the process of vacuum refining. A vacuum degree of 8 to 27 kPa is previously set on the vacuum exhaust equipment side with the vacuum valve closed, and the vacuum valve is opened at the same time as the processing is started to improve the vacuum degree on the vacuum refining furnace side. The vacuum control method described.
度制御用圧力調整弁の弁開度を調整し、排ガス流量の1
０％以下を水封式真空ポンプの上流側に戻すことで、速
やかに真空精錬炉内の真空度を向上せしめることを特徴
とする請求項１又は２記載の真空度制御方法。3. When adding an alloy / auxiliary material into the furnace, the valve opening of the vacuum control pressure adjusting valve is adjusted to adjust the exhaust gas flow rate to 1%.
The degree of vacuum control according to claim 1 or 2, wherein the degree of vacuum in the vacuum refining furnace is rapidly improved by returning 0% or less to the upstream side of the water-sealed vacuum pump.
活性ガス、窒素あるいはそれらの混合ガスを吹込み、排
ガス中の酸素濃度を７vol％以下とした後、精錬用酸素
含有ガスを真空精錬炉内に吹込むことを特徴とする請求
項１〜３のいずれか１項記載の真空度制御方法。4. After starting the evacuation of the furnace, an inert gas, nitrogen or a mixed gas thereof is blown into the vacuum refining furnace to reduce the oxygen concentration in the exhaust gas to 7 vol% or less, and then the refining oxygen-containing gas is vacuumed. The method for controlling the degree of vacuum according to any one of claims 1 to 3, wherein the method is blowing into a refining furnace.
空弁、単独あるいは複数段のエジェクタ−式真空排気装
置、水封式真空ポンプが順次配列され、かつ水封式真空
ポンプから排気された排ガスの一部を水封式真空ポンプ
の上流側に戻す真空制御用圧力調節弁を有することを特
徴とする真空排気設備列。5. A vacuum refining furnace, an exhaust gas cooler, a dust collector, a vacuum valve, a single or multiple-stage ejector-type vacuum exhaust device, and a water-sealed vacuum pump are sequentially arranged, and the water-sealed vacuum pump is used for exhausting. A vacuum exhaust equipment line comprising a vacuum control pressure control valve for returning a part of exhaust gas to the upstream side of a water-sealed vacuum pump.
Priority Applications (12)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001391274A JP3922923B2 (en) | 2001-12-25 | 2001-12-25 | Method and apparatus for controlling degree of vacuum in vacuum exhaust equipment |
| CN2009101301344A CN101538639B (en) | 2001-09-20 | 2002-09-20 | Apparatus for refining molten iron containing chromium |
| EP02799368A EP1431404B1 (en) | 2001-09-20 | 2002-09-20 | Method for refining molten iron containing chromium |
| KR1020047004145A KR100662895B1 (en) | 2001-09-20 | 2002-09-20 | Method for refining molten iron containing chromium |
| DE60238776T DE60238776D1 (en) | 2001-09-20 | 2002-09-20 | METHOD FOR REFINING CHROMIUM-CONTAINING MELT-LIQUID IRON |
| US10/490,459 US20040245682A1 (en) | 2001-09-20 | 2002-09-20 | Method for refining molten iron containing chromium |
| BRPI0212732-6B1A BR0212732B1 (en) | 2001-09-20 | 2002-09-20 | gas blow multi-step refining method for the refining of a steel to the molten chrome in a refining vessel |
| TW091121638A TW564262B (en) | 2001-09-20 | 2002-09-20 | A method and apparatus for refining Cr containing melt |
| BRPI0216050A BRPI0216050B1 (en) | 2001-09-20 | 2002-09-20 | refining apparatus for cast chrome steels |
| PCT/JP2002/009701 WO2003027335A1 (en) | 2001-09-20 | 2002-09-20 | Method for refining molten iron containing chromium |
| CNA02818467XA CN1556865A (en) | 2001-09-20 | 2002-09-20 | Method and device for refining molten chromium-containing steel |
| US11/712,778 US7497987B2 (en) | 2001-09-20 | 2007-02-28 | Refining method and refining apparatus for chromium-contained molten steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001391274A JP3922923B2 (en) | 2001-12-25 | 2001-12-25 | Method and apparatus for controlling degree of vacuum in vacuum exhaust equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2003193125A true JP2003193125A (en) | 2003-07-09 |
| JP3922923B2 JP3922923B2 (en) | 2007-05-30 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001391274A Expired - Lifetime JP3922923B2 (en) | 2001-09-20 | 2001-12-25 | Method and apparatus for controlling degree of vacuum in vacuum exhaust equipment |
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| Country | Link |
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| JP (1) | JP3922923B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008115452A (en) * | 2006-11-08 | 2008-05-22 | Nippon Steel Engineering Co Ltd | Evacuation system |
| JP2009074161A (en) * | 2007-08-29 | 2009-04-09 | Nippon Steel Engineering Co Ltd | Vacuum-degassing method |
| JP2009221509A (en) * | 2008-03-14 | 2009-10-01 | Nippon Steel Corp | Method for starting gas-exhaustion in vacuum-degassing apparatus |
| KR101181832B1 (en) * | 2010-12-16 | 2012-09-11 | 주식회사 포스코 | Apparatus for controlling in parallel vacuum equipment |
| KR20190019495A (en) * | 2017-08-18 | 2019-02-27 | 주식회사 포스코 | Vacuum degassing system and method of vacuum degassing using the same |
| CN115466827A (en) * | 2022-08-29 | 2022-12-13 | 武汉钢铁有限公司 | Double-plant three-unit combined heat storage RH vacuum refining steam system |
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2001
- 2001-12-25 JP JP2001391274A patent/JP3922923B2/en not_active Expired - Lifetime
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008115452A (en) * | 2006-11-08 | 2008-05-22 | Nippon Steel Engineering Co Ltd | Evacuation system |
| JP2009074161A (en) * | 2007-08-29 | 2009-04-09 | Nippon Steel Engineering Co Ltd | Vacuum-degassing method |
| JP2009221509A (en) * | 2008-03-14 | 2009-10-01 | Nippon Steel Corp | Method for starting gas-exhaustion in vacuum-degassing apparatus |
| KR101181832B1 (en) * | 2010-12-16 | 2012-09-11 | 주식회사 포스코 | Apparatus for controlling in parallel vacuum equipment |
| KR20190019495A (en) * | 2017-08-18 | 2019-02-27 | 주식회사 포스코 | Vacuum degassing system and method of vacuum degassing using the same |
| KR101998749B1 (en) | 2017-08-18 | 2019-07-10 | 주식회사 포스코 | Vacuum degassing system and method of vacuum degassing using the same |
| CN115466827A (en) * | 2022-08-29 | 2022-12-13 | 武汉钢铁有限公司 | Double-plant three-unit combined heat storage RH vacuum refining steam system |
| CN115466827B (en) * | 2022-08-29 | 2023-08-18 | 武汉钢铁有限公司 | Double-factory three-unit combined heat storage RH vacuum refining steam system |
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Free format text: JAPANESE INTERMEDIATE CODE: R250 |
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| EXPY | Cancellation because of completion of term |