JP4103236B2 - Glass manufacturing equipment by vacuum degassing - Google Patents

Glass manufacturing equipment by vacuum degassing Download PDF

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Publication number
JP4103236B2
JP4103236B2 JP10186099A JP10186099A JP4103236B2 JP 4103236 B2 JP4103236 B2 JP 4103236B2 JP 10186099 A JP10186099 A JP 10186099A JP 10186099 A JP10186099 A JP 10186099A JP 4103236 B2 JP4103236 B2 JP 4103236B2
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Japan
Prior art keywords
vacuum degassing
tank
molten glass
liquid level
upstream
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JP10186099A
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JP2000290021A (en
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浩治 大林
祐輔 竹居
年安 河口
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AGC Inc
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Asahi Glass Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
    • C03B5/225—Refining
    • C03B5/2252—Refining under reduced pressure, e.g. with vacuum refiners

Description

【０００１】
【発明の属する技術分野】
本発明は、連続的に供給される溶融ガラスから気泡を除去するための溶融ガラスの減圧脱泡を利用したガラスの製造装置に関する。
【０００２】
【従来の技術】
従来より、成形されたガラス製品の品質を向上させるために、図３に示すように、ガラスの原材料を溶解槽で溶融した溶融ガラスを成形装置で成形する前に溶融ガラス内に発生した気泡を除去する減圧脱泡装置を有するガラスの製造装置が用いられている。このようなガラスの製造装置の一例が図３に示される。
図３に示される減圧脱泡装置１１０は、溶解槽１２０内の溶融ガラスＧを減圧脱泡処理して、次の処理槽に連続的に供給するプロセスに用いられるものであって、減圧脱泡する際には、真空吸引されて内部が減圧される減圧ハウジング１１２内に設けられ、減圧ハウジング１１２と共に減圧される減圧脱泡槽１１４と、その両端部に、下方に向かって垂直に取り付けられた上昇管１１６および下降管１１８が配置されており、上昇管１１６の下端は、溶解槽１２０に連通する上流側ピット１２２の溶融ガラスＧ内に浸漬されており、下降管１１８の下端は、同様に、次の処理槽（図示せず）に連通する下流側ピット１２４の溶融ガラスＧ内に浸漬されている。
【０００３】
そして、減圧脱泡槽１１４は、図示しない真空ポンプによって真空吸引されて内部が減圧される減圧ハウジング１１２内におおむね水平に設けられ、減圧ハウジング１１２と共に減圧脱泡槽１１４の内部が１／３〜１／２０気圧に減圧されているので、上流側ピット１２２内の脱泡処理前の溶融ガラスＧは、上昇管１１６によって吸引上昇されて減圧脱泡槽１１４に導入され、減圧脱泡槽１１４内で減圧脱泡処理した後、すなわち、溶融ガラスＧ内の気泡が溶融ガラスＧの液表面に浮上して破泡し、この破泡した気泡内のガス成分を減圧脱泡槽１１４内の減圧された上部空間１１４ｓに放出した後、下降管１１８によって下降させて下流側ピット１２４に導出される。
このようにして減圧脱泡が行われるが、減圧脱泡槽１１４内の減圧脱泡処理は、溶融ガラスＧを浮上して破泡する気泡内のガス成分を減圧脱泡槽１１４から外部に放出するため、上部空間１１４ｓが設けられる必要があり、減圧脱泡槽１１４内を溶融ガラスＧで溢れるばかりに一杯に充たすことのないように、減圧脱泡槽１１４を上下方向に移動して、減圧脱泡槽１１４の高さ方向の位置を調整することができる。
【０００４】
減圧ハウジング１１２は、金属製、例えばステンレス製または耐熱鋼製のケーシングであり、外部から真空ポンプ（図示せず）等によって真空吸引されて内部が減圧され、内部に設けられた減圧脱泡槽１１４内を所定の圧力、例えば１／２０〜１／３気圧に減圧して維持する。
この減圧ハウジング１１２内の減圧脱泡槽１１４、上昇管１１６および下降管１１８の周囲には、これらを断熱被覆する耐火物製レンガなどの断熱材１３０が配設されている。
また、減圧脱泡装置１１０は、上流側ピット１２２のほか下流側ピット１２４内にも溶融ガラスＧを満たし、サイホンの原理を用いて溶融ガラスＧを流すため、減圧脱泡処理の開始前、上昇管１１６および下降管１１８から溶融ガラスＧを吸引上昇させておく必要がある。そのため、減圧脱泡装置１１０は、上流側案内ピット１２２から下流側案内ピット１２４に溶融ガラスＧを導くバイパス管路１３２およびバイパス管路１３２を遮断する仕切り板１３４を有する。
【０００５】
このような減圧脱泡装置１１０では、溶融ガラスＧ内の気泡を効率よく減圧吸引するために定められる適切な圧力は、例えば、硫酸ナトリウム（Ｎａ2 ＳＯ4 ）等をガラス原料に少量混合添加して減圧脱泡槽内で溶融ガラス内の気泡の成長浮上を促進させる清澄剤の添加量や、溶解槽でガラス原料を溶解する温度や、ガラス原料を大気圧雰囲気下で溶解する際の大気圧の圧力等の溶解条件、あるいは減圧脱泡槽内に流す溶融ガラスの種類によって変化する。そのため、適切な圧力で減圧脱泡する場合、減圧脱泡槽１１４内の溶融ガラスＧの液面レベルが減圧脱泡槽１１４の天井部に達して溶融ガラスＧが溢れ出ることがなく、減圧脱泡槽１１４内で溶融ガラスＧの液面レベルが所定の範囲内に来るように、溶融ガラスの種類等の条件によって定まる適切な圧力に応じて、減圧脱泡槽１１４の高さ方向の位置を調整しなければならない。
【０００６】
このような適切な圧力は、場合によっては、比較的低い圧力、例えば１／２０気圧にしなければならない。この場合、減圧脱泡槽１１４内の圧力が低いため、それに応じて減圧脱泡槽１１４から溶融ガラスＧが溢れることのないように減圧脱泡槽１１４を高く吊り上げなければならず、例えば圧力が１／２０気圧の場合、約４．５ｍも吊り上げる必要がある。そのため、上記例のような約４．５ｍもの高さにまで吊り上げることのできる特別の設備を備えなければならない。しかも、減圧脱泡装置１１０を大型化する場合、減圧脱泡装置の大型化にともなって大型化した減圧脱泡槽を高さ方向に自在に、しかも上記例のように高さ方向に約４．５ｍも吊り上げることのできる巨大な設備を備える必要があるが、このような設備を備えることは困難である。
【０００７】
このような問題に対して、特開平５−２６２５３０号公報は、上昇管を上昇する溶融ガラスＧの流量をスクリューポンプを回転させて抑制するとともに、下降管を下降する溶融ガラスＧの流量をスクリューポンプを回転させて増加し、減圧脱泡槽内の溶融ガラスＧの液面レベルを減圧脱泡処理前の溶解槽等の溶融ガラスＧの自由表面レベルと実質的に同一レベルに維持することで、減圧脱泡槽の高さ方向の位置を低くすることができる減圧脱泡方法およびその装置を開示している。この方法によれば、上昇管を上昇する溶融ガラスＧ、あるいは下降管を下降する溶融ガラスＧの流量を制御することで、減圧脱泡槽内の圧力を低く設定しても、減圧脱泡槽から溶融ガラスＧが溢れ出ることを防ぐことができる。
【０００８】
このような上記技術は、大流量の溶融ガラスを減圧脱泡処理して、気泡を含まない高品質なガラスを大量に得ることが望まれる大型の減圧脱泡装置に対して、特に有効であると考えられた。つまり、溶融ガラスＧの流量を制御して、減圧脱泡槽内の溶融ガラスＧの液面レベルを溶解槽等の溶融ガラスＧの自由表面レベルと実質的に同一レベルに維持し、減圧脱泡槽の吊り上げを不要とする上記溶融ガラスＧの流量制御技術を用いることで、減圧脱泡装置の大型化、さらには減圧脱泡装置の低コスト化が図られると考えられた。
【０００９】
【発明が解決しようとする課題】
しかし、スクリューポンプを備え溶融ガラスの流量の制御を行う上記技術を用いて減圧脱泡装置を大型化する場合、以下の問題が発生することがわかった。
すなわち、減圧脱泡装置の大型化に伴って、スクリューポンプも大型化しなければならず、例えば、一日に減圧脱泡可能な溶融ガラスＧの流量を１トン／ｄａｙから４００トン／ｄａｙに規模を拡大する場合、上記スクリューポンプの径を例えば１５０ｍｍから８００ｍｍに、スクリューポンプの長さを１１００ｍｍにしなければならず、その結果スクリューポンプの材質を例えばモリブデンとした場合、スクリューポンプの重量は約５．５トンとなる。このような高重量物のスクリューポンプを支持し、モーター等を介して回転するスクリューポンプの回転を制御することはほとんど不可能に近い。また、スクリューポンプを支持し、回転を制御することができる程度にスクリューポンプを小さくできたとしても、スクリューポンプが配置され溶融ガラスＧを減圧脱泡槽に導く管路等とスクリューポンプとの間のクリアランスを流量制限のために小さくする必要があり、このクリアランスを小さくすると、僅かな変形や歪みによってスクリューポンプのスクリューがスクリューポンプが配置される管路等に接触して擦れ、破損するおそれがあるといった問題が生じる。
【００１０】
一方、減圧脱泡槽の高さ方向の位置を固定して、溶解槽から上昇管、減圧脱泡槽および下降管を経由する溶融ガラスＧの流路を一連の閉管路として形成することで、減圧脱泡槽の高さ方向の位置を調整する吊り上げ設備を不要とすることもできる。
しかし、減圧脱泡を効率よく行なうための減圧脱泡槽内の圧力条件は、上記溶解槽における溶解条件、あるいは減圧脱泡槽内に流す溶融ガラスの種類によって変化する。したがって、溶解槽から上昇管、減圧脱泡槽および下降管を経由する溶融ガラスの流路を一連の閉管路として形成して、減圧脱泡槽の高さ方向の位置を固定すると、減圧脱泡槽内の液面レベルを一定に維持することが困難になる。前記液面レベルが変化すると、これを契機として液面レベル付近の減圧脱泡槽の構成材料、たとえば白金合金や電鋳レンガの侵蝕が急速に進行し、溶融ガラス中に前記構成材料が流出して製品欠陥となり品質を維持することができなくなったり、あるいは減圧脱泡槽の寿命が短くなったりするおそれがある。
【００１１】
そこで、本発明の目的は、前記問題点を解決することにあり、大流量の溶融ガラスの減圧脱泡処理を行う場合でも、大型の吊り上げ設備を備えることなく、溶解槽における溶解条件や溶融ガラスの種類が変化しても減圧脱泡槽内の溶融ガラスの液面レベルを実質的に一定にできる実用的な減圧脱泡によるガラスの製造装置を提供することにある。
【００１２】
【課題を解決するための手段】
上記目的を達成するために、本発明は、溶融ガラスを減圧脱泡して処理槽に導出するガラスの製造装置であって、ガラス原料を溶解した溶融ガラスが大気圧雰囲気下、自由表面を有する溶解槽と、真空吸引されて内部が減圧される減圧ハウジングと、この減圧ハウジング内に設けられ、溶融ガラスの減圧脱泡を行う減圧脱泡槽と、この減圧脱泡槽に連通して設けられ、減圧脱泡前の溶融ガラスを吸引上昇させて前記減圧脱泡槽に導入する上昇管と、前記減圧脱泡槽に連通して設けられ、減圧脱泡後の溶融ガラスを前記減圧脱泡槽から下降させて導出する下降管と、前記溶解槽と前記上昇管とを連通する上流側接続部と、前記下降管と前記処理槽とを連通する下流側接続部と、前記上昇管および前記上流側接続部の少なくとも一つに設けられ、前記減圧脱泡槽内の溶融ガラスの液面レベルを制御する上流側・液面制御手段と、前記下降管および前記下流側接続部の少なくとも一つに設けられ、前記減圧脱泡槽内の溶融ガラスの液面レベルを制御する下流側・液面制御手段とを備え、前記上流側接続部、前記上昇管、前記減圧脱泡槽、前記下降管および前記下流側接続部は、一体化して固定されて前記溶解槽から前記処理槽に導かれる一連の溶融ガラスの管路を形成し、前記上流側・液面制御手段および前記下流側・液面制御手段の少なくともいずれか一方は、前記減圧脱泡槽内の溶融ガラスの液面レベルを、前記溶解槽の溶融ガラスの液面レベルより３．５ｍ以上高い位置に制御する液面制御手段であることを特徴とする減圧脱泡によるガラスの製造装置を提供するものである。
【００１３】
ここで、前記上流側接続部は、溶融ガラスを下降させる上流側下降管を備え、この上流側下降管の上方が前記溶解槽と接続され、下方が前記上昇管の下方と接続され、あるいは、前記下流側接続部は、溶融ガラスを上昇させる下流側上昇管を備え、この下流側上昇管の下方が前記下降管の下方と接続され、上方が前記処理槽と接続されることが好ましい。また、前記上流側・液面制御手段および／または前記下流側・液面制御手段は、回転自在なスクリューポンプであることが好ましい。また、前記スクリューポンプは、回転方向および回転速度を制御して前記減圧脱泡槽内の溶融ガラスの液面レベルを制御するスクリューポンプであることが好ましい。さらに、前記上流側・液面制御手段であるスクリューポンプは、減圧脱泡開始時に、前記上流側接続部の溶融ガラスを前記上昇管から前記減圧脱泡槽内に送り込むスクリューポンプであることが好ましい。
【００１４】
【発明の実施の形態】
以下、本発明の減圧脱泡によるガラスの製造装置について、添付の図面に示される好適実施例を基に詳細に説明する。
【００１５】
図１は、本発明の減圧脱泡によるガラスの製造装置の一実施例を示す概略断面図である。図１に示すガラスの製造装置は、ガラス原料を溶解して溶融ガラスＧを貯溜する溶解槽２０と、溶融ガラスを減圧脱泡処理して溶融ガラスの気泡を減圧吸引する減圧脱泡装置１０とから構成される。
【００１６】
溶解槽２０は、燃料ガスを燃焼して得られる火炎の熱を利用して、また電熱を利用して得られる約１５５０℃以上の高温でガラス原料を溶融した溶融ガラスＧで充たされる槽であり、減圧脱泡装置１０の前に配置される。溶解槽２０では、溶融ガラスＧはその液表面が大気圧Ｐａにさらされて自由表面を形成する。
【００１７】
減圧脱泡装置１０は、図１に示すように、本発明の減圧脱泡によるガラスの製造装置の主要部分を構成し、溶解槽２０内から溶融ガラスＧを減圧脱泡槽１４に吸引上昇させ、減圧された減圧脱泡槽１４において減圧脱泡処理を行い、次の処理槽２６、例えばフロートバスなどの板状の成形処理槽や瓶などの成形作業槽などに連続的に供給するプロセスに用いられるもので、基本的に、減圧ハウジング１２、減圧脱泡槽１４、上昇管１６、下降管１８、上流側接続部２２および下流側接続部２４とからなる。
【００１８】
減圧ハウジング１２は、減圧脱泡槽１４を減圧する際の気密性を確保するためのケーシング（圧力容器）として機能するものであり、本実施例では、ほぼ門型に形成されて、減圧脱泡槽１４、上昇管１６および下降管１８の全体を包み込むように構成される。この減圧ハウジング１２は、減圧脱泡槽１４に必要とされる気密性および強度を有するものであれば、その材質、構造は特に限定されるものではないが、金属製、特にステンレス製または耐熱鋼製とすることが好ましい。減圧ハウジング１２には、右上部に真空吸引して内部を減圧する吸引口１２ｃが設けられており、図示しない真空ポンプによって真空吸引されて減圧ハウジング１２の内部が減圧され、そのほぼ中央部に配置された減圧脱泡槽１４内を所定の圧力、例えば、１／２０〜１／３気圧に減圧して維持するように構成される。
【００１９】
減圧ハウジング１２のほぼ中央部には、減圧脱泡槽１４がおおむね水平に配置される。この減圧脱泡槽１４の流路の断面は、円形でもよいが、大流量の溶融ガラスＧの減圧脱泡処理を行うには長方形が好ましい。
この減圧脱泡槽１４の左端部には上昇管１６の上端部が、減圧脱泡槽１４の右端部には下降管１８の上端部がそれぞれ下方に向かって垂直に連通される。そして、上昇管１６および下降管１８は門型に形成された減圧ハウジング１２の脚部１２ａ，１２ｂをそれぞれ貫通するように配設されており、上昇管１６および下降管１８の下端は、それぞれ溶解槽２０に連通する上流側接続部２２および処理槽２６に連通する下流側接続部２４に接続され、上流側接続部２２、上昇管１６、減圧脱泡槽１４、下降管１８および下流側接続部３４は、一体化して固定され一連の閉管路を構成する。
【００２０】
上流側接続部２２は、溶解槽２０から溶融ガラスＧを下降させる上流側下降管３２を備え、この上流側下降管３２の上方は溶解槽２０と接続され、下方は上昇管１６の下方と接続される。一方、下流側接続部２４は、溶融ガラスＧを上昇させる下流側上昇管３４を備え、この下流側上昇管３４の下方は下降管１８の下方と接続され、上方は処理槽２６と接続される。
また、上流側接続部２２の上流側下降管３２内部に、減圧脱泡槽１４内の溶融ガラスＧの液面レベルを制御する上流側・液面制御手段として正逆に回転可能な上流側スクリューポンプ３６が溶融ガラスＧ内に浸されて設けられる。また、下流側接続部２４の下流側上昇管３４の内部には、減圧脱泡槽１４内の溶融ガラスＧの液面レベルを制御する下流側・液面制御手段として下流側スクリューポンプ３８が溶融ガラスＧ内に浸されて設けられる。
【００２１】
減圧脱泡槽１４の上部には、減圧ハウジング１２を図示しない真空ポンプ等によって真空吸引することによって減圧脱泡槽１４内を所定の圧力（圧力Ｐｂ、１／２０〜１／３気圧）に維持するため、減圧ハウジング１２と連通する吸引孔１４ａ，１４ｂが設けられる。また、減圧脱泡槽１４には、溶融ガラスＧの液面レベルが所定の高さに調整され、その上部に圧力Ｐｂに減圧された上部空間１４ｓが形成される。
減圧ハウジング１２と、減圧脱泡槽１４、上昇管１６および下降管１８との間は、耐火物製レンガなどの断熱材３０で充填されて断熱被覆され、外側から金属製の減圧ハウジング１２、耐火物製レンガからなる断熱材３０および減圧脱泡槽１４ななどの多層断面構造となっている。この断熱材３０は、減圧脱泡槽１４の真空吸引の支障とならないように、通気性を有する断熱材によって構成される。
【００２２】
図１に示す本発明の減圧脱泡装置１０においては、一連の管路を構成する減圧脱泡槽１４、上昇管１６および下降管１８、上流側上昇管３２および下流側上昇管３４、ならびに溶解槽２０および次の処理槽２６がいずれも耐火物製レンガを組んで構成される。
すなわち、減圧脱泡装置１０において、溶融ガラスの自由表面を持つ溶解槽２０から次の処理槽２６までの間の一連の管路を電鋳耐火物製レンガを組んで構成することにより、高温耐蝕性や高温耐熱性に優れた白金合金製の流路よりもコストを大幅に低減させることができ、減圧脱泡槽１４を自由な形状で、かつ自由な肉厚に設計することが可能となり、大流量の溶融ガラスＧを減圧脱泡処理することのできる大型の減圧脱泡装置１０が実現するとともに、より高温での減圧脱泡処理も行えるようになるからである。
なお、白金合金を用いてもよいのは勿論である。
【００２３】
上流側接続部２２および下流側接続部２４には、それぞれ上流側スクリューポンプ３６および下流側スクリューポンプ３８が配設される。上流側スクリューポンプ３６および下流側スクリューポンプ３８は、回転自在なシャフトおよびこのシャフトにらせん状に巻き付けられた羽根を備え、溶融ガラスＧの高温に耐えることのできる白金合金やモリブデン等の金属で形成される。溶融ガラスＧは、上流側下降管３２内を下降して上昇管１６より減圧脱泡槽１４内に流入する。上流側スクリューポンプ３６のシャフトは正回転することで、溶融ガラスＧが減圧脱泡槽１４内に流入しにくくなるようにし、逆回転することで反対に流入しやすくすることができる。また、溶融ガラスＧは、下流側上昇管３４内を上昇して流出する。下流側スクリューポンプ３８のシャフトは正回転することで、溶融ガラスＧが流出しにくくなるようにし、逆回転することで流出しやすくすることができる。たとえば、溶解槽における溶解条件の変化等によって減圧脱泡槽１４内の圧力をさらに下げる必要が生じた場合は、上流側スクリューポンプ３６を正回転させた上で、回転速度を制御して減圧脱泡槽１４内の溶融ガラスＧの液面レベルを実質的に一定にできる。一方、下流側スクリューポンプ３８のシャフトは、この場合逆回転させたうえで回転速度を制御して溶融ガラスＧの流量を実質的に一定に保ち、前記溶融ガラスＧの液面レベルを実質的に一定にできる。
【００２４】
また、減圧脱泡処理は、サイホンの原理を利用するため、減圧脱泡処理開始時、上昇管１６、減圧脱泡槽１４および下降管１８内に溶融ガラスＧを充たす必要があるが、上流側スクリューポンプ３６のシャフトは逆回転することで、減圧脱泡開始時、溶融ガラスＧを上流側下降管３２の下方に押し下げて、上昇管１６を充たし、さらに上昇管１６より溶融ガラスＧを減圧脱泡槽１４内に流入させて減圧脱泡槽１４の所定の高さまで充たし、さらに下降管１８を充たすことができる。このため、従来の減圧脱泡装置１１０のような、上流側案内ピット１２２から下流側案内ピット１２４に溶融ガラスＧを導くバイパス管路１３２およびバイパス管路１３２を遮断する仕切り板１３４を不要とし、減圧脱泡装置１０の製作コストを低減することができる。
なお、上流側スクリューポンプ３６や下流側スクリューポンプ３８とともに、バイパス管路１３２およびバイパス管路１３２を遮断する仕切り板１３４を設けてもよく、この場合、上流側スクリューポンプ３６を逆回転させることで、減圧脱泡槽１４内を真空ポンプによる吸引とともに、上昇管１６、減圧脱泡槽１４および下降管１８内に溶融ガラスＧを容易かつ短時間に充たすことができる。
上流側スクリューポンプ３６および下流側スクリューポンプ３８による減圧脱泡槽１４内の溶融ガラスＧの液面レベルは、各々のシャフトを回転させるモーター等を電気的に制御することによって行う。
【００２５】
図１に示す本発明の減圧脱泡装置１０において、減圧脱泡槽１４、上昇管１６および下降管１８、上流側下降管３２および下流側上昇管３４は一連の管路を構成することで、従来の減圧脱泡装置１１０のように減圧脱泡槽１１４内の圧力に応じて減圧脱泡槽１１４を吊り上げる必要がなくなる。これによって、従来問題となっていた大型の吊り上げ設備が不要になる。
【００２６】
また、減圧脱泡槽１４は、一連の管路を構成するため、高さ方向の位置が固定されるが、その固定される位置は、減圧脱泡槽１４内の溶融ガラスＧの液面レベルが、溶解槽２０の自由表面レベルに対して実質的に高く、好ましくはその差が３．５メートル以上となるように設けられる。この場合、減圧脱泡槽１４内の圧力Ｐｂは、０．０５気圧（１／２０気圧）〜０．２８気圧とするのが好ましい。大流量の溶融ガラスＧを減圧脱泡処理する大型の減圧脱泡装置の場合、従来、流量調整手段によって溶融ガラスＧの流量を調整して、減圧脱泡槽内の溶融ガラスＧの液面レベルを実質的に溶解槽の液面レベルと同一レベルに維持するため、大気圧Ｐａと減圧脱泡槽１４内の圧力Ｐｂとの差分によって生じる溶融ガラスＧの液面レベルの上昇分全体を、流量調整手段であるスクリューポンプを用いて流量調整しなければならない。そのため上述したようにスクリューポンプは大型化し、その結果、高重量物になってしまい、スクリューポンプの支持が困難になる他、高重量物のスクリューポンプの慣性力も大きくなるため、スクリューポンプの制御自体も困難になる。
【００２７】
しかし、本発明によれば、減圧脱泡槽１４内の液面レベルが、溶解槽２０の液面レベルより実質的に高くなるように設けられるので、上流側スクリューポンプ３６や下流側スクリューポンプ３８の直径を小さくして現実的かつ実用的な大きさにすることができる。また、上流側下降管３２や下流側上昇管３４と上流側スクリューポンプ３６や下流側スクリューポンプ３８との間のクリアランスを従来に比べて広げることができ、僅かな変形が生じても上流側スクリューポンプ３６や下流側スクリューポンプ３８が上流側下降管３２や下流側上昇管３４の壁面と接触し擦れ、破損するおそれはなくなる。
【００２８】
すなわち、減圧脱泡装置１０は、減圧脱泡槽１４の高さ調整のための上下移動はできず固定されているが、減圧脱泡槽１４内の溶融ガラスＧの液面レベルは液面制御手段である上流側スクリューポンプ３６や下流側下流側スクリューポンプ３８で実質的に一定となるように制御される。また、上流側スクリューポンプ３６や下流側下流側スクリューポンプ３８は現実的かつ実用的な大きさにすることができる。
その結果、溶解槽２０での溶解条件や溶融ガラスＧの種類によって変わる効率のよい減圧脱泡条件に合わせることができる。
【００２９】
なお、本実施例では、上流側スクリューポンプ３６および下流側スクリューポンプ３８を上流側接続部２２および下流側接続部２４内に配置しているが、上昇管１６や下降管１８内に配置してもよい。
また、本発明の減圧脱泡によるガラスの製造装置の液面制御手段は、上記スクリューポンプに限られず、流れを制御できるものであればよく、図２に示すように、溶解槽２０から流出する溶融ガラスＧの流れを孔４０で制御するオリフィス４２を用いてもよい。
【００３０】
次に、本発明の減圧脱泡によるガラスの製造装置装置の作用を説明する。
溶解槽２０では、従来から用いられているように、燃料用油や燃焼ガスで燃焼させて得られる火炎の燃焼熱をガラス原料に吹きつけて、あるいは電熱を利用してガラス原料を溶解して溶融ガラスＧを溶解槽２０内に貯溜する。
つぎに減圧脱泡装置１０は、運転を開始するに先立って、上流側下降管３２、上昇管１６、減圧脱泡槽１４、下降管１８、および下流側上昇管３４によって構成される一連の管路を予め加熱する。管路を予め加熱するのは、高温の溶融ガラスＧが比較的低温の管路表面と接触すると、溶融ガラスＧは冷却され粘度が上がり、溶融ガラスＧ内に含まれる気泡の減圧吸引を行うことが困難となるからである。さらに、この冷却された溶融ガラスＧが管路表面に固着し、管路を狭くするからである。
【００３１】
その後、溶解槽２０に貯溜した溶融ガラスＧを図示しない仕切り板を開放して溶融ガラスＧを上流側下降管３２内に流入させ溶融ガラスＧを充たす。
つぎに、上流側スクリューポンプ３６を逆回転して、溶融ガラスＧを上昇管１６の方向に送り出して上昇管１６内を溶融ガラスＧで充たし、減圧脱泡槽１４内に溶融ガラスＧの一定の液面レベルを作り、さらに下降管１８内を溶融ガラスＧで充たし下降管１８内を下降させ、下流側接続部２４を充たす。その後、図示されない真空ポンプで減圧ハウジング１２内を所定の圧力（圧力Ｐｂ）に減圧する。
これによって、サイホンの原理より溶解槽２０から減圧脱泡槽１４を通って次の処理槽２６に溶融ガラスＧを定常的に流下させることができる。
【００３２】
すなわち、図１に示す減圧脱泡装置１０において、減圧脱泡槽１４は、図示しない真空ポンプによって真空吸引されて、所定の圧力（圧力Ｐｂ）、例えば１／２０〜１／３気圧に維持されているので、溶融ガラスＧは、自由液面を有する溶解槽２０に加わる大気圧Ｐａと減圧脱泡槽１４内の圧力Ｐｂとの圧力差によって、溶解槽２０より上流側下降管３２および上昇管１６を通って減圧脱泡槽１４に吸引上昇され、溶融ガラスＧが減圧脱泡槽１４内を流下する間に、溶融ガラスＧ中の気泡は、溶融ガラスＧ中を液面まで浮上し、液面上で破泡し、破泡した気泡内部のガス成分を上部空間１４ｓに放出する。放出されたガス成分は、図示されない真空ポンプによって排出される。こうして、溶融ガラスＧ中から気泡が除去される。
このようにして、脱泡処理された溶融ガラスＧは、減圧脱泡槽１４内から下降管１８に導出され、下降管１８内を下降して下流側上昇管３４を通って次の処理槽２６（例えば成形処理槽）に導出される。
【００３３】
減圧脱泡槽１４は、上流側下降管３２、上昇管１６、減圧脱泡槽１４、下降管１８、および下流側上昇管３４によって構成される一連の管路によって設置高さが固定され、その設置位置は、減圧脱泡槽１４内の溶融ガラスＧの液面レベルが、自由表面を有する溶解槽２０の液面レベルより実質的に高くなるように設けられる。溶解槽２０における溶解条件等が変化し、これにともなって圧力Ｐｂを変化させなければならなくなった場合、上流側スクリューポンプ３６と下流側スクリューポンプ３８のシャフトの回転方向と回転速度を制御して、減圧脱泡槽１４内の溶融ガラスＧの液面を実質的に変化させないようにする。
【００３４】
これにより、減圧脱泡槽１４の溶融ガラスＧの液面レベルの変動に伴う減圧脱泡槽１４の構成材料の侵蝕が進行して溶融ガラスＧ中に前記構成材料が流出して製品欠点を引き起こすことなく、また従来のような減圧脱泡槽の上下移動による高さ方向の位置調整を行なうことなく、減圧脱泡槽１４内の圧力Ｐｂの調整が可能となる。
また、上流側スクリューポンプ３６や下流側スクリューポンプ３８で減圧脱泡槽１４内の溶融ガラスＧの液面レベルを制御して、溶解槽２０での溶解条件や溶融ガラスＧの種類によって変わる効率のよい減圧脱泡条件に合わせることができ、従来制限されて困難であった減圧脱泡槽１２内の圧力Ｐｂの調整を行なうことができる。特に、溶解槽２０で得られた溶融ガラスＧが溶解槽２０から上昇管１６上昇するまで、約半日以上かかるため、その間に溶解槽２０内の溶融ガラスＧの自由表面と接する大気圧雰囲気の大気圧Ｐａが変化（例えば、台風等の低気圧が通過する）し、効率のよい減圧脱泡条件が変化する場合がある。このような場合、液面制御手段である上流側スクリューポンプ３６や下流側スクリューポンプ３８を用いることで、減圧脱泡槽１２内の圧力Ｐｂを効率のよい減圧脱泡条件に合わせることができる。
【００３５】
以上、本発明の減圧脱泡によるガラスの製造装置について詳細に説明したが、本発明は上記実施例に限定されず、本発明の要旨を逸脱しない範囲において、各種の改良および変更を行ってもよいのはもちろんである。
【００３６】
【発明の効果】
以上、詳細に説明したように、本発明によれば、減圧脱泡槽内の溶融ガラスの液面レベルを制御する液面制御手段を備え、溶解槽から、上流側接続部、上昇管、減圧脱泡槽、下降管および下流側接続部を一体化して固定され、一連の溶融ガラスの管路を形成し、減圧脱泡槽内の溶融ガラスの液面レベルが、自由表面を有する溶解槽等の溶融ガラスの液面レベルより実質的に高くなるように構成されるため、大流量の溶融ガラスの減圧脱泡処理を行う場合でも、従来の減圧脱泡装置のような減圧脱泡槽を減圧脱泡槽内の圧力に応じて高さ方向に昇降する大型の吊り上げ設備を不要とし、また液面制御手段によって減圧脱泡槽内の溶融ガラスの液面レベルを一定に保つので、減圧脱泡槽の構成材料の侵蝕を抑制し減圧脱泡槽の寿命を延ばすことができる。また、減圧脱泡槽内の溶融ガラスの液面レベルが一定に保たれて減圧脱泡槽の構成材料の侵蝕が抑制されるので、構成材料の溶融ガラスへの流出が少なく最終ガラス製品の品質を一定に保つことができる。さらに、大流量の溶融ガラスを減圧脱泡処理する大型の減圧脱泡装置に比して液面制御手段を小型化し、現実的かつ実用的な大きさで構成することができ、液面制御手段を用いて現実的かつ実用的に大流量の溶融ガラスの減圧脱泡処理を行うことができる。
【００３７】
また、上流側スクリューポンプは、減圧脱泡処理開始時、逆回転することで、上流側接続部にある溶融ガラスを上昇管から減圧脱泡槽内に送り込むことができるので、従来の減圧脱泡装置のように、減圧脱泡処理前に用いるバイパス管路を備える必要がなく、装置の製作コストの削減や装置の簡素化を図ることができる。
【図面の簡単な説明】
【図１】 本発明の減圧脱泡によるガラスの製造装置の一実施例の概略断面図を示す。
【図２】 本発明の減圧脱泡によるガラスの製造装置の、図１に示される態様と異なる上流側接続部の概略断面図を示す。
【図３】 従来技術の溶融ガラスの減圧脱泡装置の概略断面図を示す。
【符号の説明】
１０，１１０ 減圧脱泡装置
１２，１１２ 減圧ハウジング
１２ａ，１２ｂ 脚部
１２ｃ 吸引口
１４，１１４ 減圧脱泡槽
１４ａ，１４ｂ 吸引孔
１６，１１６ 上昇管
１８，１１８ 下降管
２０，１２０ 溶解槽
２２ 上流側接続部
２４ 下流側接続部
２６ 処理槽
３０，１３０ 断熱材
３２ 上流側下降管
３４ 下流側上昇管
３６ 上流側スクリューポンプ
３８ 下流側スクリューポンプ
４０ 孔
４２ オリフィス
１２２ 上流側ピット
１２４ 下流側ピット
Ｇ 溶融ガラス
Ｐａ 大気圧
Ｐｂ 圧力[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for producing glass using vacuum degassing of molten glass for removing bubbles from continuously supplied molten glass.
[0002]
[Prior art]
Conventionally, in order to improve the quality of the molded glass product, as shown in FIG. 3, bubbles generated in the molten glass before the molten glass obtained by melting the glass raw material in the melting tank is molded by the molding apparatus. A glass production apparatus having a vacuum degassing apparatus for removal is used. An example of such a glass manufacturing apparatus is shown in FIG.
The vacuum degassing apparatus 110 shown in FIG. 3 is used in a process of vacuum degassing the molten glass G in the melting tank 120 and continuously supplying it to the next processing tank. In this case, a vacuum degassing tank 114 is provided in a vacuum housing 112 that is vacuum-sucked to decompress the inside, and a vacuum degassing tank 114 that is decompressed together with the vacuum housing 112, and vertically attached to both ends thereof. An ascending pipe 116 and a descending pipe 118 are arranged, and the lower end of the ascending pipe 116 is immersed in the molten glass G of the upstream pit 122 communicating with the melting tank 120, and the lower end of the descending pipe 118 is similarly In the molten glass G of the downstream pit 124 communicating with the next processing tank (not shown).
[0003]
The decompression defoaming tank 114 is provided generally horizontally in the decompression housing 112 that is vacuumed by a vacuum pump (not shown) to decompress the inside, and the inside of the decompression defoaming tank 114 together with the decompression housing 112 is 1/3. Since the pressure is reduced to 1/20 atm, the molten glass G before the defoaming treatment in the upstream pit 122 is sucked up by the riser 116 and introduced into the depressurized defoaming tank 114. In other words, the bubbles in the molten glass G float on the liquid surface of the molten glass G and break the bubbles, and the gas components in the broken bubbles are decompressed in the vacuum deaeration tank 114. After being discharged into the upper space 114s, it is lowered by the downcomer 118 and led to the downstream pit 124.
In this way, vacuum degassing is performed. In the vacuum degassing process in the vacuum degassing tank 114, the gas components in the bubbles that rise and break the molten glass G are released from the vacuum degassing tank 114 to the outside. Therefore, it is necessary to provide the upper space 114s, and the vacuum degassing tank 114 is moved up and down to prevent the vacuum degassing tank 114 from being filled with the molten glass G. The position of the defoaming tank 114 in the height direction can be adjusted.
[0004]
The decompression housing 112 is a casing made of metal, for example, stainless steel or heat-resistant steel. The decompression housing 112 is decompressed by vacuum suction from the outside by a vacuum pump (not shown) or the like, and the decompression defoaming tank 114 provided inside. The inside is reduced to a predetermined pressure, for example 1/20 to 1/3 atm, and maintained.
A heat insulating material 130 such as a refractory brick is provided around the vacuum degassing tank 114, the ascending pipe 116, and the descending pipe 118 in the decompression housing 112 so as to thermally insulate them.
Further, the vacuum degassing apparatus 110 fills the molten glass G not only in the upstream pit 122 but also in the downstream pit 124 and flows the molten glass G using the siphon principle. It is necessary to suck and raise the molten glass G from the pipe 116 and the downcomer pipe 118. Therefore, the vacuum degassing apparatus 110 includes a bypass conduit 132 that guides the molten glass G from the upstream guide pit 122 to the downstream guide pit 124 and a partition plate 134 that blocks the bypass conduit 132.
[0005]
In such a vacuum degassing apparatus 110, an appropriate pressure determined for efficiently vacuuming and sucking bubbles in the molten glass G is, for example, sodium sulfate (Na 2 SO Four ) Etc. are added to the glass raw material in a small amount and the amount of fining agent added to accelerate the growth and floating of bubbles in the molten glass in the vacuum defoaming tank, the temperature at which the glass raw material is melted in the melting tank, and the glass raw material are increased. It varies depending on the melting conditions such as the pressure of atmospheric pressure when melting in an atmospheric pressure atmosphere, or the type of molten glass that flows in the vacuum defoaming tank. Therefore, when vacuum degassing is performed at an appropriate pressure, the liquid level of the molten glass G in the vacuum degassing tank 114 does not reach the ceiling of the vacuum degassing tank 114 and the molten glass G does not overflow. The position of the vacuum degassing tank 114 in the height direction is set according to an appropriate pressure determined by conditions such as the type of the molten glass so that the liquid level of the molten glass G is within a predetermined range in the foam tank 114. Must be adjusted.
[0006]
Such a suitable pressure must in some cases be a relatively low pressure, for example 1/20 atmosphere. In this case, since the pressure in the vacuum degassing tank 114 is low, the vacuum degassing tank 114 must be lifted high so that the molten glass G does not overflow from the vacuum degassing tank 114 accordingly. In the case of 1/20 atmosphere, it is necessary to lift about 4.5 m. Therefore, special equipment that can be lifted to a height of about 4.5 m as in the above example must be provided. Moreover, when the vacuum degassing apparatus 110 is increased in size, the vacuum degassing tank increased in size with the increase in size of the vacuum degassing apparatus can be freely adjusted in the height direction, and about 4 in the height direction as in the above example. Although it is necessary to provide a huge facility capable of lifting as much as 0.5 m, it is difficult to provide such a facility.
[0007]
In order to solve such a problem, Japanese Patent Laid-Open No. 5-262530 discloses that the flow rate of the molten glass G that rises up the riser pipe is controlled by rotating a screw pump, and the flow rate of the molten glass G that descends the downcomer pipe is screwed. By rotating the pump, the liquid level of the molten glass G in the vacuum degassing tank is maintained at substantially the same level as the free surface level of the molten glass G in the melting tank before the vacuum degassing treatment. Discloses a vacuum degassing method and an apparatus for reducing the height position of the vacuum degassing tank. According to this method, even if the pressure in the vacuum degassing tank is set low by controlling the flow rate of the molten glass G that rises up the rising pipe or the molten glass G that moves down the downcomer, the vacuum degassing tank Therefore, it is possible to prevent the molten glass G from overflowing.
[0008]
Such a technique is particularly effective for a large-sized vacuum degassing apparatus that is desired to obtain a large amount of high-quality glass that does not contain bubbles by subjecting a large flow rate of molten glass to vacuum degassing. It was considered. That is, by controlling the flow rate of the molten glass G, the liquid level of the molten glass G in the vacuum degassing tank is maintained at substantially the same level as the free surface level of the molten glass G in the melting tank, etc. It was thought that by using the flow rate control technology for the molten glass G that does not require the lifting of the tank, the vacuum degassing apparatus can be increased in size and the cost of the vacuum degassing apparatus can be reduced.
[0009]
[Problems to be solved by the invention]
However, it has been found that the following problems occur when the vacuum degassing apparatus is enlarged using the above-described technique for controlling the flow rate of the molten glass with a screw pump.
That is, as the vacuum degassing apparatus increases in size, the screw pump must also increase in size. For example, the flow rate of molten glass G that can be degassed under reduced pressure per day is increased from 1 ton / day to 400 ton / day. When the diameter of the screw pump is increased from 150 mm to 800 mm, the length of the screw pump must be set to 1100 mm. As a result, when the screw pump is made of molybdenum, for example, the weight of the screw pump is about 5 mm. .5 tons. It is almost impossible to control the rotation of a screw pump that supports such a heavy-weight screw pump and rotates via a motor or the like. Also, even if the screw pump can be made small enough to support the screw pump and control the rotation, the screw pump is arranged between a pipe line and the like that leads the molten glass G to the vacuum degassing tank and the screw pump. It is necessary to reduce the clearance of the screw pump to limit the flow rate, and if this clearance is reduced, the screw of the screw pump may come into contact with the pipe line where the screw pump is placed and be damaged due to slight deformation or distortion. A problem arises.
[0010]
On the other hand, by fixing the position in the height direction of the vacuum degassing tank, and forming the flow path of the molten glass G from the melting tank via the riser pipe, the vacuum degassing tank and the downfall pipe as a series of closed pipe lines, It is also possible to eliminate the need for lifting equipment that adjusts the position in the height direction of the vacuum degassing tank.
However, the pressure conditions in the vacuum degassing tank for efficiently performing the vacuum degassing vary depending on the melting conditions in the melting tank or the type of molten glass flowing in the vacuum degassing tank. Therefore, if the molten glass flow path from the melting tank to the rising pipe, the vacuum degassing tank, and the descending pipe is formed as a series of closed pipes, and the position in the height direction of the vacuum degassing tank is fixed, the vacuum degassing is performed. It becomes difficult to keep the liquid level in the tank constant. When the liquid level changes, the material of the vacuum degassing tank near the liquid level, for example, platinum alloy or electrocast bricks erodes rapidly, and the constituent material flows into the molten glass. As a result, the product may become defective and the quality cannot be maintained, or the life of the vacuum degassing tank may be shortened.
[0011]
Therefore, an object of the present invention is to solve the above-mentioned problems, and even when performing vacuum degassing treatment of a large flow rate of molten glass, the melting conditions in the melting tank and the molten glass are not provided without a large lifting equipment. An object of the present invention is to provide a practical apparatus for producing glass by reduced pressure defoaming which can make the liquid level of the molten glass in the reduced pressure defoaming tank substantially constant even if the kind of the defoaming is changed.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is a glass manufacturing apparatus for degassing molten glass and deriving it to a treatment tank, wherein the molten glass having a glass raw material dissolved has a free surface in an atmospheric pressure atmosphere. A melting tank, a vacuum housing that is vacuumed to reduce the inside, a vacuum degassing tank that is provided in the vacuum housing and performs vacuum degassing of molten glass, and is provided in communication with the vacuum degassing tank. A riser pipe that sucks and raises the molten glass before vacuum degassing and introduces it into the vacuum degassing tank; and is provided in communication with the vacuum degassing tank; A downcomer pipe that descends and leads out, an upstream connection part that communicates the dissolution tank and the riser pipe, a downstream connection part that communicates the downcomer pipe and the treatment tank, the riser pipe and the upstream Provided in at least one of the side connections, The upstream side / liquid level control means for controlling the liquid level of the molten glass in the vacuum degassing tank, and provided in at least one of the downcomer and the downstream connection portion, the melting in the vacuum degassing tank A downstream side / liquid level control means for controlling the liquid level of the glass, and the upstream side connection part, the riser pipe, the vacuum degassing tank, the downcomer pipe and the downstream side connection part are integrally fixed. A series of molten glass pipes led from the melting tank to the processing tank, and at least one of the upstream side / liquid level control means and the downstream side / liquid level control means Is The liquid level of the molten glass in the vacuum degassing tank is controlled to a position higher by 3.5 m or more than the liquid level of the molten glass in the melting tank. Liquid level control means An apparatus for producing glass by vacuum degassing is provided.
[0013]
Here, the upstream connection portion includes an upstream downcomer that lowers the molten glass, the upper part of the upstream downcomer is connected to the dissolution tank, and the lower part is connected to the lower part of the riser, or It is preferable that the downstream connection portion includes a downstream ascending pipe that raises the molten glass, a lower part of the downstream ascending pipe is connected to a lower part of the descending pipe, and an upper part thereof is connected to the treatment tank. Further, the upstream side / liquid level control means and / or the downstream side / liquid level control means are preferably rotatable screw pumps. The screw pump controls the liquid surface level of the molten glass in the vacuum degassing tank by controlling the rotation direction and the rotation speed. Screw pump It is preferable. Further, the screw pump as the upstream side / liquid level control means feeds the molten glass of the upstream connection portion from the riser pipe into the vacuum degassing tank at the start of vacuum degassing. Screw pump It is preferable.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the apparatus for producing glass by vacuum degassing according to the present invention will be described in detail based on the preferred embodiments shown in the accompanying drawings.
[0015]
FIG. 1 is a schematic cross-sectional view showing an embodiment of an apparatus for producing glass by vacuum degassing according to the present invention. The glass manufacturing apparatus shown in FIG. 1 includes a melting tank 20 that melts a glass raw material and stores molten glass G, and a vacuum defoaming apparatus 10 that vacuum-suctions molten glass bubbles by vacuuming the molten glass. Consists of
[0016]
The melting tank 20 is a tank filled with a molten glass G obtained by melting a glass raw material at a high temperature of about 1550 ° C. or higher obtained by using the heat of a flame obtained by burning fuel gas and using electric heat. It is arranged in front of the vacuum degassing device 10. In the melting tank 20, the liquid glass G is exposed to atmospheric pressure Pa to form a free surface.
[0017]
As shown in FIG. 1, the vacuum degassing apparatus 10 constitutes a main part of a glass manufacturing apparatus by vacuum degassing according to the present invention, and sucks and raises molten glass G from the melting tank 20 to the vacuum degassing tank 14. In the process of performing a vacuum degassing process in the decompressed vacuum degassing tank 14 and continuously supplying it to the next processing tank 26, for example, a plate-shaped molding processing tank such as a float bath or a molding work tank such as a bottle. It is used and basically comprises a decompression housing 12, a decompression deaeration tank 14, an ascending pipe 16, a descending pipe 18, an upstream connection part 22, and a downstream connection part 24.
[0018]
The decompression housing 12 functions as a casing (pressure vessel) for ensuring airtightness when decompressing the decompression defoaming tank 14. In this embodiment, the decompression housing 12 is formed in a substantially gate shape, and decompressed defoaming is performed. The tank 14, the ascending pipe 16, and the descending pipe 18 are configured to wrap around. The material and structure of the decompression housing 12 are not particularly limited as long as the decompression housing 12 has airtightness and strength required for the decompression defoaming tank 14, but is made of metal, particularly stainless steel or heat resistant steel. It is preferable to make it. The decompression housing 12 is provided with a suction port 12c for vacuum suction at the upper right part to decompress the inside, and the inside of the decompression housing 12 is decompressed by a vacuum pump (not shown), and is arranged at the substantially central part thereof. The inside of the reduced pressure degassing tank 14 is configured to be maintained at a predetermined pressure, for example, 1/20 to 1/3 atm.
[0019]
A vacuum defoaming tank 14 is arranged approximately horizontally at a substantially central portion of the vacuum housing 12. The cross section of the flow path of the vacuum degassing tank 14 may be circular, but a rectangular shape is preferable for performing the vacuum defoaming treatment of the high flow rate molten glass G.
The upper end portion of the rising pipe 16 is communicated with the left end portion of the vacuum degassing tank 14 and the upper end portion of the descending pipe 18 is vertically communicated downward with the right end portion of the vacuum degassing tank 14. The ascending pipe 16 and the descending pipe 18 are disposed so as to penetrate the leg portions 12a and 12b of the decompression housing 12 formed in a gate shape, respectively, and the lower ends of the ascending pipe 16 and the descending pipe 18 are dissolved. Connected to the upstream connection portion 22 communicating with the tank 20 and the downstream connection portion 24 communicating with the treatment tank 26, the upstream connection portion 22, the rising pipe 16, the vacuum degassing tank 14, the descending pipe 18, and the downstream connection section. 34 is integrated and fixed to form a series of closed pipes.
[0020]
The upstream connecting portion 22 includes an upstream downcomer pipe 32 that lowers the molten glass G from the melting tank 20, the upper part of the upstream downcomer pipe 32 is connected to the melting tank 20, and the lower part is connected to the lower part of the uprising pipe 16. Is done. On the other hand, the downstream side connection portion 24 includes a downstream side rising pipe 34 that raises the molten glass G. The lower side of the downstream side rising pipe 34 is connected to the lower side of the down pipe 18, and the upper side is connected to the processing tank 26. .
In addition, an upstream screw that can be rotated forward and backward as upstream / liquid level control means for controlling the liquid level of the molten glass G in the vacuum degassing vessel 14 inside the upstream downcomer 32 of the upstream connection portion 22. A pump 36 is provided immersed in the molten glass G. A downstream screw pump 38 is melted in the downstream riser 34 of the downstream connection portion 24 as downstream / liquid level control means for controlling the liquid level of the molten glass G in the vacuum degassing vessel 14. It is provided soaked in the glass G.
[0021]
Above the vacuum degassing tank 14, the vacuum housing 12 is maintained at a predetermined pressure (pressure Pb, 1/20 to 1/3 atm) by vacuum suction of the vacuum housing 12 by a vacuum pump (not shown). Therefore, suction holes 14 a and 14 b communicating with the decompression housing 12 are provided. Further, in the vacuum degassing tank 14, the liquid surface level of the molten glass G is adjusted to a predetermined height, and an upper space 14s reduced to the pressure Pb is formed in the upper part thereof.
The space between the decompression housing 12 and the decompression defoaming tank 14, the rising pipe 16 and the descending pipe 18 is filled with a heat insulating material 30 such as a brick made of refractory, and is covered with heat insulation. It has a multilayer cross-sectional structure such as a heat insulating material 30 made of a product brick and a vacuum degassing tank 14. This heat insulating material 30 is comprised with the heat insulating material which has air permeability so that the vacuum suction of the pressure reduction degassing tank 14 may not be obstructed.
[0022]
In the vacuum degassing apparatus 10 of the present invention shown in FIG. 1, the vacuum degassing tank 14, the rising pipe 16 and the lowering pipe 18, the upstream rising pipe 32 and the downstream rising pipe 34 that constitute a series of pipelines, and dissolution Both the tank 20 and the next treatment tank 26 are configured by assembling refractory bricks.
That is, in the vacuum degassing apparatus 10, a series of pipelines between the melting tank 20 having a free surface of molten glass and the next processing tank 26 is constructed by assembling bricks made of electroformed refractory, thereby providing high temperature corrosion resistance. Cost can be drastically reduced compared to a platinum alloy flow path with excellent heat resistance and high temperature heat resistance, and the vacuum degassing tank 14 can be designed in a free shape and a free thickness, This is because a large-sized vacuum degassing apparatus 10 capable of performing a vacuum degassing process on a large flow rate of molten glass G is realized, and a vacuum degassing process at a higher temperature can be performed.
Of course, a platinum alloy may be used.
[0023]
An upstream screw pump 36 and a downstream screw pump 38 are disposed in the upstream connection portion 22 and the downstream connection portion 24, respectively. The upstream screw pump 36 and the downstream screw pump 38 are each made of a metal such as platinum alloy or molybdenum that can withstand the high temperature of the molten glass G, and has a rotatable shaft and blades spirally wound around the shaft. Is done. The molten glass G descends in the upstream downcomer 32 and flows into the vacuum degassing tank 14 through the ascending tube 16. By rotating the shaft of the upstream screw pump 36 forward, , Molten glass G Inside the vacuum degassing tank 14 Flow It can be made difficult to enter, and can be made easier to flow in reverse by rotating in reverse. Moreover, the molten glass G rises in the downstream ascending pipe 34 and flows out. The shaft of the downstream screw pump 38 rotates forward , Melt The molten glass G can be made difficult to flow out, and can be easily flowed out by rotating in reverse. For example, if it is necessary to further reduce the pressure in the vacuum degassing tank 14 due to changes in the dissolution conditions in the dissolution tank, etc., the upstream screw pump 36 is rotated forward and the rotational speed is controlled to reduce the pressure. The liquid level of the molten glass G in the foam tank 14 can be made substantially constant. On the other hand, the shaft of the downstream screw pump 38 is reversely rotated in this case, and the rotational speed is controlled to keep the flow rate of the molten glass G substantially constant, so that the liquid level of the molten glass G is substantially maintained. Can be constant.
[0024]
In addition, since the vacuum degassing process uses the principle of siphon, it is necessary to fill the rising glass 16, the vacuum degassing tank 14, and the descending pipe 18 with molten glass G at the start of the vacuum degassing process. By rotating the shaft of the screw pump 36 in the reverse direction, when the vacuum degassing starts, the molten glass G is pushed down below the upstream downcomer 32 to fill the riser 16, and the molten glass G is depressurized from the riser 16. It can be made to flow into the bubble tank 14 and be filled up to a predetermined height of the vacuum degassing tank 14, and further the downcomer 18 can be filled. Therefore, unlike the conventional vacuum degassing apparatus 110, the bypass pipe 132 that guides the molten glass G from the upstream guide pit 122 to the downstream guide pit 124 and the partition plate 134 that blocks the bypass pipe 132 are unnecessary. The manufacturing cost of the vacuum degassing apparatus 10 can be reduced.
In addition to the upstream screw pump 36 and the downstream screw pump 38, a bypass pipe 132 and a partition plate 134 that blocks the bypass pipe 132 may be provided. In this case, the upstream screw pump 36 is rotated in the reverse direction. The vacuum degassing tank 14 can be filled with the molten glass G easily and in a short time in the ascending pipe 16, the vacuum degassing tank 14 and the descending pipe 18 together with suction by a vacuum pump.
The liquid level of the molten glass G in the vacuum degassing tank 14 by the upstream screw pump 36 and the downstream screw pump 38 is controlled by electrically controlling a motor or the like that rotates each shaft.
[0025]
In the vacuum degassing apparatus 10 of the present invention shown in FIG. 1, the vacuum degassing tank 14, the rising pipe 16 and the descending pipe 18, the upstream descending pipe 32 and the downstream rising pipe 34 constitute a series of pipelines, Unlike the conventional vacuum degassing apparatus 110, it is not necessary to lift the vacuum degassing tank 114 in accordance with the pressure in the vacuum degassing tank 114. This eliminates the need for large lifting equipment that has been a problem in the past.
[0026]
Moreover, since the vacuum degassing tank 14 constitutes a series of pipelines, the position in the height direction is fixed, but the fixed position is the liquid level of the molten glass G in the vacuum degassing tank 14. Is substantially higher than the free surface level of the dissolution tank 20, and preferably the difference is 3.5 meters or more. In this case, the pressure Pb in the vacuum degassing tank 14 is preferably 0.05 atm (1/20 atm) to 0.28 atm. In the case of a large-sized vacuum degassing apparatus that depressurizes a large flow rate of molten glass G, conventionally, the liquid level of the molten glass G in the vacuum degassing tank is adjusted by adjusting the flow rate of the molten glass G by the flow rate adjusting means. Is maintained at the same level as the liquid level of the melting tank, the entire increase in the liquid level of the molten glass G caused by the difference between the atmospheric pressure Pa and the pressure Pb in the vacuum degassing tank 14 The flow rate must be adjusted using a screw pump as an adjusting means. Therefore, as described above, the screw pump becomes larger, and as a result, becomes a heavy object, which makes it difficult to support the screw pump and also increases the inertial force of the heavy-weight screw pump. Also becomes difficult.
[0027]
However, according to the present invention, the liquid level in the vacuum degassing tank 14 is provided so as to be substantially higher than the liquid level in the dissolution tank 20, so that the upstream screw pump 36 and the downstream screw pump 38 are provided. The diameter can be reduced to a realistic and practical size. Further, the clearance between the upstream downcomer pipe 32 or the downstream ascending pipe 34 and the upstream screw pump 36 or the downstream screw pump 38 can be widened as compared with the prior art, and even if a slight deformation occurs, the upstream screw There is no possibility that the pump 36 or the downstream screw pump 38 contacts and rubs against the wall surfaces of the upstream descending pipe 32 or the downstream ascending pipe 34 and is damaged.
[0028]
That is, the vacuum degassing apparatus 10 is fixed so that it cannot move up and down for height adjustment of the vacuum degassing tank 14, but the liquid level of the molten glass G in the vacuum degassing tank 14 is liquid level controlled. The upstream screw pump 36 and the downstream downstream screw pump 38 which are means are controlled so as to be substantially constant. Further, the upstream screw pump 36 and the downstream downstream screw pump 38 can be made practical and practical in size.
As a result, it is possible to match the efficient depressurization and defoaming conditions that vary depending on the melting conditions in the melting tank 20 and the type of the molten glass G.
[0029]
In this embodiment, the upstream screw pump 36 and the downstream screw pump 38 are disposed in the upstream connection portion 22 and the downstream connection portion 24, but are disposed in the ascending pipe 16 and the descending pipe 18. Also good.
Moreover, the liquid level control means of the apparatus for producing glass by vacuum degassing according to the present invention is not limited to the screw pump as long as it can control the flow, and as shown in FIG. An orifice 42 that controls the flow of the molten glass G with the holes 40 may be used.
[0030]
Next, the operation of the apparatus for producing glass by vacuum degassing according to the present invention will be described.
In the melting tank 20, as conventionally used, the combustion heat of a flame obtained by burning with fuel oil or combustion gas is blown to the glass raw material, or the glass raw material is dissolved using electric heat. Molten glass G is stored in the melting tank 20.
Next, prior to the start of operation, the vacuum degassing apparatus 10 is a series of pipes constituted by an upstream downcomer 32, a riser 16, a vacuum degassing tank 14, a downcomer 18, and a downstream riser 34. Preheat the path. The pipe is preheated when the high-temperature molten glass G comes into contact with the surface of the relatively low-temperature pipe, the molten glass G is cooled to increase the viscosity, and the bubbles contained in the molten glass G are sucked under reduced pressure. This is because it becomes difficult. Further, this is because the cooled molten glass G adheres to the pipe surface and narrows the pipe.
[0031]
Thereafter, the molten glass G stored in the melting tank 20 is opened by a partition plate (not shown), and the molten glass G is caused to flow into the upstream downcomer 32 to fill the molten glass G.
Next, the upstream screw pump 36 is reversely rotated, the molten glass G is sent out in the direction of the riser 16, the inside of the riser 16 is filled with the molten glass G, and the molten glass G is fixed in the vacuum degassing vessel 14. The liquid level is made, and the inside of the downcomer pipe 18 is filled with molten glass G, the inside of the downcomer pipe 18 is lowered, and the downstream connection portion 24 is filled up. Thereafter, the inside of the decompression housing 12 is decompressed to a predetermined pressure (pressure Pb) by a vacuum pump (not shown).
Thereby, the molten glass G can be steadily made to flow down from the melting tank 20 to the next processing tank 26 through the vacuum degassing tank 14 by the principle of siphon.
[0032]
That is, in the vacuum degassing apparatus 10 shown in FIG. 1, the vacuum degassing tank 14 is vacuumed by a vacuum pump (not shown) and maintained at a predetermined pressure (pressure Pb), for example, 1/20 to 1/3 atmospheric pressure. Therefore, the molten glass G has an upstream descending pipe 32 and a rising pipe upstream of the melting tank 20 due to a pressure difference between the atmospheric pressure Pa applied to the melting tank 20 having a free liquid level and the pressure Pb in the vacuum degassing tank 14. 16, while the molten glass G flows down in the vacuum degassing tank 14, bubbles in the molten glass G rise to the liquid surface in the molten glass G, The bubbles break on the surface, and the gas components inside the broken bubbles are released into the upper space 14s. The released gas component is discharged by a vacuum pump (not shown). In this way, bubbles are removed from the molten glass G.
In this way, the defoamed molten glass G is led out from the reduced pressure defoaming tank 14 to the downcomer 18, descends in the downcomer 18 and passes through the downstream ascending pipe 34 to the next processing tank 26. (E.g., a molding tank).
[0033]
The decompression defoaming tank 14 is fixed in installation height by a series of pipes constituted by the upstream downcomer 32, the riser 16, the decompression defoaming tank 14, the downcomer 18 and the downstream riser 34. The installation position is provided such that the liquid level of the molten glass G in the vacuum degassing tank 14 is substantially higher than the liquid level of the dissolution tank 20 having a free surface. When the melting conditions in the melting tank 20 change and the pressure Pb must be changed accordingly, the rotational direction and rotational speed of the shafts of the upstream screw pump 36 and the downstream screw pump 38 are controlled. The liquid level of the molten glass G in the vacuum degassing tank 14 is not changed substantially.
[0034]
Thereby, the erosion of the constituent material of the vacuum degassing tank 14 accompanying the fluctuation of the liquid level of the molten glass G in the vacuum degassing tank 14 progresses, and the constituent material flows into the molten glass G, causing a product defect. Without adjusting the position in the height direction by the vertical movement of the vacuum degassing tank as in the prior art, the pressure Pb in the vacuum degassing tank 14 can be adjusted.
Further, the liquid level of the molten glass G in the vacuum degassing tank 14 is controlled by the upstream screw pump 36 and the downstream screw pump 38, and the efficiency varies depending on the melting conditions in the melting tank 20 and the type of the molten glass G. The pressure Pb in the vacuum degassing tank 12 can be adjusted, which can be adjusted to good vacuum degassing conditions and has been difficult to be limited in the past. In particular, since it takes about half a day or more for the molten glass G obtained in the melting tank 20 to rise from the melting tank 20 to the riser 16, a large atmospheric pressure atmosphere is in contact with the free surface of the molten glass G in the melting tank 20 during that time. The atmospheric pressure Pa changes (for example, a low atmospheric pressure such as a typhoon passes), and the efficient vacuum degassing conditions may change. In such a case, the pressure Pb in the vacuum degassing tank 12 can be adjusted to efficient vacuum degassing conditions by using the upstream screw pump 36 and the downstream screw pump 38 which are liquid level control means.
[0035]
As mentioned above, although the manufacturing apparatus of the glass by the vacuum degassing of this invention was demonstrated in detail, this invention is not limited to the said Example, In the range which does not deviate from the summary of this invention, even if various improvements and changes are performed. Of course it is good.
[0036]
【The invention's effect】
As described above in detail, according to the present invention, the liquid level control means for controlling the liquid level of the molten glass in the vacuum degassing tank is provided, and the upstream connection portion, the riser pipe, the vacuum pressure is provided from the melting tank. A defoaming tank, a downcomer, and a downstream connection part are integrated and fixed to form a series of molten glass conduits, and the molten glass liquid level in the vacuum degassing tank has a free surface, etc. Because it is configured to be substantially higher than the liquid level of the molten glass, the vacuum degassing tank like the conventional vacuum degassing equipment is decompressed even when vacuum defoaming treatment of a large flow rate of molten glass is performed. Since there is no need for a large lifting equipment that moves up and down in the height direction according to the pressure in the defoaming tank, and the liquid level control means keeps the liquid level of the molten glass in the vacuum defoaming tank constant, vacuum degassing It is possible to extend the life of the vacuum degassing tank by suppressing the erosion of the constituent materials of the tank. Kill. In addition, since the liquid surface level of the molten glass in the vacuum degassing tank is kept constant and the erosion of the constituent materials of the vacuum degassing tank is suppressed, the quality of the final glass product is low because the component materials do not flow into the molten glass. Can be kept constant. Furthermore, the liquid level control means can be made smaller and configured in a practical and practical size compared to a large-sized vacuum degassing apparatus for vacuum degassing treatment of a large flow rate of molten glass. It is possible to carry out a vacuum defoaming treatment of a molten glass having a large flow rate realistically and practically using
[0037]
In addition, the upstream screw pump reversely rotates at the start of the vacuum degassing process, so that the molten glass at the upstream connection portion can be fed into the vacuum degassing tank from the riser pipe. Unlike the apparatus, there is no need to provide a bypass conduit used before the vacuum degassing treatment, and the manufacturing cost of the apparatus can be reduced and the apparatus can be simplified.
[Brief description of the drawings]
FIG. 1 shows a schematic cross-sectional view of one embodiment of a glass production apparatus by vacuum degassing according to the present invention.
FIG. 2 is a schematic cross-sectional view of an upstream connecting portion different from the embodiment shown in FIG. 1 in the apparatus for producing glass by vacuum degassing according to the present invention.
FIG. 3 is a schematic cross-sectional view of a conventional vacuum degassing apparatus for molten glass.
[Explanation of symbols]
10,110 Vacuum degassing equipment
12,112 decompression housing
12a, 12b Leg
12c Suction port
14,114 Vacuum degassing tank
14a, 14b Suction hole
16,116 riser
18, 118 downcomer
20,120 dissolution tank
22 Upstream connection
24 Downstream connection
26 treatment tank
30,130 Thermal insulation
32 Upstream downcomer
34 Downstream riser
36 Upstream screw pump
38 Downstream screw pump
40 holes
42 Orifice
122 Upstream pit
124 Downstream pit
G Molten glass
Pa atmospheric pressure
Pb pressure

Claims (5)

溶融ガラスを減圧脱泡して処理槽に導出するガラスの製造装置であって、
ガラス原料を溶解した溶融ガラスが大気圧雰囲気下、自由表面を有する溶解槽と、
真空吸引されて内部が減圧される減圧ハウジングと、
この減圧ハウジング内に設けられ、溶融ガラスの減圧脱泡を行う減圧脱泡槽と、この減圧脱泡槽に連通して設けられ、減圧脱泡前の溶融ガラスを吸引上昇させて前記減圧脱泡槽に導入する上昇管と、
前記減圧脱泡槽に連通して設けられ、減圧脱泡後の溶融ガラスを前記減圧脱泡槽から下降させて導出する下降管と、
前記溶解槽と前記上昇管とを連通する上流側接続部と、
前記下降管と前記処理槽とを連通する下流側接続部と、
前記上昇管および前記上流側接続部の少なくとも一つに設けられ、前記減圧脱泡槽内の溶融ガラスの液面レベルを制御する上流側・液面制御手段と、
前記下降管および前記下流側接続部の少なくとも一つに設けられ、前記減圧脱泡槽内の溶融ガラスの液面レベルを制御する下流側・液面制御手段とを備え、
前記上流側接続部、前記上昇管、前記減圧脱泡槽、前記下降管および前記下流側接続部は、一体化して固定されて前記溶解槽から前記処理槽に導かれる一連の溶融ガラスの管路を形成し、
前記上流側・液面制御手段および前記下流側・液面制御手段の少なくともいずれか一方は、前記減圧脱泡槽内の溶融ガラスの液面レベルを、前記溶解槽の溶融ガラスの液面レベルより３．５ｍ以上高い位置に制御する液面制御手段であることを特徴とする減圧脱泡によるガラスの製造装置。A glass manufacturing apparatus for degassing molten glass under reduced pressure and leading it to a treatment tank,
A melting tank in which a molten glass in which a glass raw material is melted has a free surface under an atmospheric pressure atmosphere;
A decompression housing that is evacuated and decompressed, and
A vacuum degassing tank that is provided in the vacuum housing and performs vacuum degassing of the molten glass, and is provided in communication with the vacuum degassing tank, and sucks and raises the molten glass before the vacuum degassing, thereby reducing the vacuum degassing. A riser pipe to be introduced into the tank;
A downcomer pipe that is provided in communication with the vacuum degassing tank and that draws the molten glass after the vacuum degassing is lowered from the vacuum degassing tank;
An upstream side connection portion that communicates the dissolution tank and the riser;
A downstream side connection portion that communicates the downcomer and the treatment tank;
An upstream side / liquid level control means for controlling the liquid level of the molten glass in the vacuum degassing tank, provided in at least one of the riser pipe and the upstream side connection part;
Provided in at least one of the downcomer and the downstream side connection part, comprising a downstream side and liquid level control means for controlling the liquid level of the molten glass in the vacuum degassing tank,
The upstream connecting part, the rising pipe, the vacuum degassing tank, the downcomer pipe, and the downstream connecting part are integrally fixed and guided from the melting tank to the processing tank. Form the
At least one of the upstream side / liquid level control means and the downstream side / liquid level control means has a liquid level level of the molten glass in the vacuum degassing tank higher than a liquid level level of the molten glass in the melting tank. An apparatus for producing glass by vacuum degassing, which is liquid level control means for controlling the position to a position higher than 3.5 m. 前記上流側接続部は、溶融ガラスを下降させる上流側下降管を備え、この上流側下降管の上方が前記溶解槽と接続され、下方が前記上昇管の下方と接続され、あるいは、
前記下流側接続部は、溶融ガラスを上昇させる下流側上昇管を備え、この下流側上昇管の下方が前記下降管の下方と接続され、上方が前記処理槽と接続される請求項１に記載の減圧脱泡によるガラスの製造装置。The upstream connection portion includes an upstream downcomer that lowers the molten glass, and an upper part of the upstream downcomer is connected to the melting tank, and a lower part is connected to a lower part of the riser, or
The said downstream connection part is equipped with the downstream riser which raises a molten glass, The lower part of this downstream riser is connected with the downward direction of the said downward pipe, The upper part is connected with the said processing tank. Equipment for producing glass by vacuum degassing. 前記上流側・液面制御手段および／または前記下流側・液面制御手段は、回転自在なスクリューポンプである請求項１または２のいずれかに記載の減圧脱泡によるガラスの製造装置。  The apparatus for producing glass by vacuum degassing according to claim 1, wherein the upstream side / liquid level control means and / or the downstream side / liquid level control means are rotatable screw pumps. 前記スクリューポンプは、回転方向および回転速度を制御して前記減圧脱泡槽内の溶融ガラスの液面レベルを制御するスクリューポンプである請求項３に記載の減圧脱泡によるガラスの製造装置。The screw pump apparatus for manufacturing a glass by the vacuum degassing of claim 3 by controlling the rotation direction and the rotation speed is a screw pump for controlling the liquid level of the molten glass of the vacuum degassing vessel. 前記上流側・液面制御手段であるスクリューポンプは、減圧脱泡開始時に、前記上流側接続部の溶融ガラスを前記上昇管から前記減圧脱泡槽内に送り込むスクリューポンプである請求項３に記載の減圧脱泡によるガラスの製造装置。Screw pump is the upstream-liquid level controlling means, the vacuum at degassing start, wherein the molten glass of the upstream joint to claim 3 is a screw pump which feeds into the vacuum degassing vessel from the riser Equipment for producing glass by vacuum degassing.
JP10186099A 1999-04-08 1999-04-08 Glass manufacturing equipment by vacuum degassing Expired - Fee Related JP4103236B2 (en)

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JP4560826B2 (en) * 2001-07-18 2010-10-13 日本電気硝子株式会社 Stirrer for molten glass
JP2006306662A (en) * 2005-04-28 2006-11-09 Asahi Glass Co Ltd Vacuum defoaming method of molten glass
JP4992712B2 (en) * 2005-05-18 2012-08-08 旭硝子株式会社 Method of energizing and heating a platinum composite tube structure
US8196434B2 (en) * 2007-08-08 2012-06-12 Corning Incorporated Molten glass delivery apparatus for optical quality glass
JP5741154B2 (en) * 2011-04-07 2015-07-01 旭硝子株式会社 Glass melting furnace and molten glass outflow method
CN106698894B (en) * 2016-12-20 2019-02-15 重庆天和玻璃有限公司 A kind of glass metal defoaming device

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* Cited by examiner, † Cited by third party
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CN107709253A (en) * 2015-04-29 2018-02-16 康宁股份有限公司 Glass manufacturing equipment and method

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