200401754 玖、發明說明 (發明說明應敘明:發明所屬之技術領域、先前技術、內容、實施方式及圖式簡單說明) (一） 發明所屬之技術領域 本發明涉及浮法玻璃之製造方法，其中一熔融玻璃在金 屬熔液上在金屬池中之熱端及冷端之間游動以形成平面玻 璃且金屬熔液之氧濃度會受到影響。 (二） 先前技術 此種方法已描述在US 6094942中，其中氫氣直接導入已 熔化之錫之池中，以便與已熔化之錫中之氣體形式之氧及 氧化錫起反應而形成水及自然之錫，因此使已熔化之錫中 之氧化錫之數量減少。但氧對玻璃製程及玻璃品質之負作 用儘可能廣泛地被排除是不容易的。 依據浮法製程來製造平面玻璃時，黏度大約104dpa.s之 玻璃熔液在金屬池（特別是已熔化之錫或錫合金）上流動， 在流動之錫上進行造形而成爲一明確之厚度，且在流動之 錫上冷卻以及在黏度大約1012dpa.s時連續地由錫表面拉 出。浮法製程用之氧是一種不期望之干擾性污染。氧會藉 由與錫表面上游動之氧化錫所造成之污染（殘渣，ΊΊn pick up )而直接或間接地影響玻璃品質。爲了使由流動之金屬 錫所形成之氧化錫減少，則浮動池中須藉由導入一種氮及 氫之氣體混合物來調整該還原用之大氣。但實際上不可能 阻止氧完全由氣體大氣經由流動之錫而至玻璃帶，亦不能 防止氧由流動之錫而至玻璃帶。 氧在浮動池中例如成爲污染物而到達氮及氫所形成之氣 體中，經由側面之浮動池密封區中之縫隙，經由出口密封 200401754 區且與流動之玻璃本身相混合。氣體大氣中所含有之氧會 與氫發生交互作用之反應而形成水，與流動之錫作用而使 氧聚集且與玻璃本身發生作用。流動之錫可藉由與氣體大 氣’玻璃及陶瓷浮動池石之交互作用而容納氧氣。 (三）發明內容 本發明之目的是在浮法製程中儘可能廣泛地使氧不會對 玻璃品質產生影響。 此目的以申請專利範圍第丨向之特徵來達成，其中金屬 熔液之氧濃度會受到影響，使氧濃度不會有任何地方超過 冷端所需之溶解度。因此幾乎可完全防止有害性之氧在錫 表面上產生。 本發明之解法是以下述之考慮爲主： 流動之錫在一預定之溫度中由大氣中接收氧氣一段期間 直至達到飽和爲止。 若超過該飽和門限値，則氧由溶液中析出而形成氧化 錫’其聚集在流動之錫之表面上。 氣體大氣中及流動之錫中含有之氧量可當場（in situ ) 測量。以Zr〇2或Th〇2作爲氧離子導引用之固體電解物被測 定時所用之實驗室硏究設備長久以來已爲人知，例如可參 考 Kiokkola ， K.Wagner ， C.:Galvanic cells for the determination of the standard molar free energy of formation of metal halides，oxydes ? and sulfides at elevated temperatures. J.Electrochem.. S o c. 104 ( 1957 )以及 kiins tier，K . A . e t a 1.: Electrochemical determination of the 200401754 oxygen activity in tin melts.... G1 a s t e c h . B e r. 73 ( 2000 )，200401754 (1) Description of the invention (The description of the invention shall state: the technical field to which the invention belongs, the prior art, the content, the embodiments, and the drawings) (1) The technical field to which the invention belongs The present invention relates to a method for manufacturing float glass, in which A molten glass swims on the molten metal between the hot end and the cold end in the metal pool to form a flat glass and the oxygen concentration of the molten metal is affected. (B) the prior art such a method has been described in US 6094942, in which hydrogen is directly introduced into the pool of molten tin in order to react with oxygen and tin oxide in the form of gas in the molten tin to form water and natural Tin therefore reduces the amount of tin oxide in the molten tin. However, it is not easy to exclude the negative effects of oxygen on the glass process and glass quality as widely as possible. When manufacturing flat glass according to the float process, a glass melt with a viscosity of about 104 dpa.s flows on a metal pool (especially molten tin or tin alloy), and is formed on the flowing tin to a clear thickness And cooled on the flowing tin and continuously pulled out from the tin surface at a viscosity of about 1012 dpa.s. Oxygen used in the float process is an undesired interference pollution. Oxygen directly or indirectly affects glass quality through contamination (residue, ΊΊn pick up) caused by tin oxide moving upstream with the tin surface. In order to reduce the tin oxide formed by the flowing metal tin, the atmosphere for reduction must be adjusted in the floating bath by introducing a gas mixture of nitrogen and hydrogen. However, it is practically impossible to prevent oxygen from flowing from the atmosphere of the gas to the glass ribbon through the flowing tin, or to prevent the oxygen from flowing from the tin to the glass ribbon. Oxygen becomes a pollutant in the floating pool and reaches the gas formed by nitrogen and hydrogen. It is sealed through the gap in the sealed area of the floating pool on the side, 200401754 area through the outlet, and mixed with the flowing glass itself. The oxygen contained in the gas atmosphere interacts with hydrogen to form water, and interacts with the flowing tin to collect oxygen and interact with the glass itself. Flowing tin can contain oxygen by interacting with gas atmosphere 'glass and ceramic floating pool stones. (3) Summary of the Invention The purpose of the present invention is to make oxygen as wide as possible in the float process without affecting the glass quality. This purpose is achieved by the characteristics of the patent application scope, where the oxygen concentration of the metal melt will be affected, so that the oxygen concentration does not exceed the solubility required for the cold end in any place. Therefore, the generation of harmful oxygen on the tin surface can be almost completely prevented. The solution of the present invention is based on the following considerations: The flowing tin receives oxygen from the atmosphere at a predetermined temperature for a period of time until it reaches saturation. If the saturation threshold 超过 is exceeded, oxygen is precipitated from the solution to form tin oxide, which is collected on the surface of the flowing tin. The amount of oxygen contained in the gas atmosphere and flowing tin can be measured in situ. The laboratory research equipment used when ZrO2 or ThO2 is used as the oxygen ion guide to measure solid electrolytes has been known for a long time. For example, refer to Kiokkola, K. Wagner, C .: Galvanic cells for the determination. of the standard molar free energy of formation of metal halides, oxydes? and sulfides at elevated temperatures. J. Electrochem .. S o c. 104 (1957) and kiins tier, K. A. eta 1 .: Electrochemical determination of the 200401754 oxygen activity in tin melts .... G1 astech. Be r. 73 (2000),
6 .當場測量用之探針已描述在各種不同之專利文件中，例 、 如可參閱 US 3625026，US 377364 卜 EP 0562801B1 以及 DE 20 1 8 8 66A卜亦已發展一種可最佳化地用在浮動池中之特定 之測量感測器，這由 A.Kasper，SAINT-GOBAIN GLASS Deutschland ， Herzogenrath ； W. Kohl ， HERA-EU S ELECTRO-NITE n.V，Houthalen( B)，Theorie und Praxis der Messung der Sauerstoffaktivitat im Zinn eines6. Probes for spot measurement have been described in various patent documents, for example, see US 3625026, US 377364, EP 0562801B1 and DE 20 1 8 8 66A. They have also been developed to be optimized for use in Specific measurement sensors in the floating pool. This is made by A. Kasper, SAINT-GOBAIN GLASS Deutschland, Herzogenrath; W. Kohl, HERA-EU S ELECTRO-NITE nV, Houthalen (B), Theorie und Praxis der Messung der Sauerstoffaktivitat im Zinn eines
Floatbadesmit der CONTINOX-Sonde ， Vortrag im 泰Floatbadesmit der CONTINOX-Sonde, Vortrag im Thai
Fachausschuss IH der DGG am 11. Oktober 2000 inFachausschuss IH der DGG am 11. Oktober 2000 in
Wiirzburg中即可得知。 只藉由流體金屬中之氧含量-或錫之測定仍不能防止金 屬或錫之氧化。 本文開頭所述之US 6 094942中之方法可使流體錫中已溶 解之氧之數量下降，但缺點是：氫氣泡會造成玻璃缺陷（玻 璃下側上敞開之氣泡），當氫氣泡到達玻璃帶下方時。 利用申請專利範圍第1項中所述之“使氧濃度受適當之 ® 影響“，則可避免上述之缺點。 改良該浮法玻璃之製程所用之其它有利之措施描述在申 請專利範圍第2項之方法中，其中該金屬池之氧含量沿著 溫度斜度由熱端至冷端藉由簡易之氧分壓之測量而可在金 屬熔液中測定或在一種形成氣中測定且在發生一種正的偏 差時分別修正至較熱力學上整體系統所需之溫度相關極限 値還小之値。 200401754 其它有利之措施描述在申請專利範圍第3項至第1 5項 中〇 藉由浮動池之流體錫中氧含量之測定及控制，則在浮動 池中一般之溫度時流體錫中不會超過氧之飽和濃度且因此 不會形成氧化錫。本方法包含一些可輕易側得之控制値， 電化學測量鏈（Chain )，與製程有關之極限値及流體錫之 淨化方式。 (四）實施方式 本發明以下將依據附圖來詳述。 流體錫對氧具有特別高之親和力，使最少量之氧即可形 成氧化錫。只要未超過相對應之極限量，則氧均勻地溶解 於錫中。氧之溶解是與溫度很有關係且明顯地是以第3圖 之log[p〇2] = f(T)形式之相位圖來表示。 由第3圖（曲線20 )可知：在典型之浮動池溫度大於600 °C時含氧之流體錫之存在區域是由氧分壓小於10-24巴 (600°C )或小於10-1 1巴（1 200°C )所限制。氧分壓p〇2 表示流體錫對已溶解之氧之結合力。此種力之變化此處可 超過多個數量級。 依 據 W.A. Faischer, D. Janke Metallurgische Elektr ochemmie，Diisseldorf 19 7 5 log{p〇2(SnlSn〇2)}=(558306-189.6 · T/K)/2.303-RT) 此外，曲線2 1中顯示可溶解之最大之氧量同樣是與錫溫 度成指數關係。在一般之溫度範圍中可辨認氧之含量由最 多三個數量級變化至四個數量級且在1 2 0 0 °c時幾乎到達 200401754 1% : log{C〇2(SnlSn〇2)} = 3.45 -493 7/丁（T in k)。 ， 若在定溫時由極限溶解度移動至較低之氧分壓，則所溶 解之氧之平衡量以指數形式減少。 在製造硼矽酸鹽平面玻璃所用之浮動池中，浮動池（1 〇 ) 之熱端存在局部性之p〇2測定値（請比較第1及第2圖）， 這由第4圖可淸楚看出。形成氣中須測定氧分壓（測量點 25，27 )，流體錫中亦須測定氧分壓（測量點24，26 )。 第4圖中含有二對測量點，其中較低之氧分壓値p〇2典型 春 上是用來正規地設定此過程。 由於形成氣是用來保護及淨化該錫池1 0，則相對應之分 壓分別小於錫之分壓。這對二個測量對（pair)而言都可滿 足。須指出：在氧未異常地經由拱形孔侵入時，則會經由 玻璃（其氧之分壓介於10-3巴及0.1巴之間）持續地帶來 氧，其可以大面積方式在玻璃/錫之界面上替換。藉由形 成氣大氣來進行所需之淨化，其是藉由前後一貫之方式經 由未由玻璃覆蓋之錫池表面來達成。 ® 形成氣之氧分壓値由分子比例（ratio ) Η::!!』所定義（N2 是鈍氣且此處只用來使反應物種稀釋）。 依據前述之文獻（Fisher，Janke )，形成氣之水含量適 合下式： log{PH2〇/pH2}=：log{K(T) + (l/2)log{p〇2} 其中 l〇g{K} = 1 3000/T-2.971(T 以 K 表示） 對上述二個測量點計算相對應之水含量（總氫含量以％ -10- 200401754 成份表示）’以點線表示之曲線22，23在各別之氫/水比 例（rati 〇 )中另外表示氧分壓相對於形成氣中溫度之推導 關係。 由第4圖之資料可知：形成Sn〇2時之極限値未被超過。 但第4圖是一種純熱力學之考慮，由局部性之純測量値開 始且先決條件是：此種局部性之値通常與整體性之平衡値 相同。這正是開放式系統之條件。但此程序現況之特徵是 其它整個邊界條件：流體錫之各別之體積元素（其具有幾 乎是定値之氣體含量）以對流之方式在溫度不同之區域之 肇 間輸送’此處更適合於封閉式系統之條件。特別是含氧之 錫之體積元素由於強力之表面流而快速地由較熱之區域拖 延至較冷之區域中。這特別適用於玻璃帶2下方之類似玻 璃（且氧較多）之錫層。 就目前製程中不平常之結果而言，須另外注意溶解於錫 中之氧之絕對含量。所計算之値在第5圖中以點28，29來 表示。因此須考慮：在等熱條件下在流體錫之存在區中適 合以下之關係：[d log p〇2/d log C〇2]t = 2。 · 就上述二個所硏究之測量點而言，現在會形成很大之不 同。在1 1 00 °C時，該二個値明顯地在小於極限溶解度大約 0 · 8 %之處。現在若使熱體積元素在想法上作爲封閉式系統 而移動至較低之溫度，則在大約7 7 0 °C時達到該處之極限溶 解度’此種情形在第二種情況下直至最低之浮動池溫度6〇〇 C時仍能可靠地排除。在桌一種情況下會在冷區域中造成 不期望之自發性之S η 02析出，在第一種情況中則不會。重 -11- 200401754 要的是採用該封閉式系統，錫藉由玻璃帶2來覆蓋時可防 止該已溶解之氧反應性地與形成氣8互換。 、 上述之想法亦可反向··在較高溫度時流體錫之最大可允 許之氧分壓p〇2値須使600°C在未限制製程條件下不會超 過可容許之氧量之0.006%。 第6圖以所示之p〇2(Snl0.006%〇2)曲線30之形式作爲反 應。P02-T之組合所形成之曲線30之程序視窗可排除氧化 錫在內部析出，其上之各程序點隱藏著相位邊界（玻璃/ 錫）上已增多之玻璃缺陷之危險性。 0 由於氧化錫（Sn〇2 )沈澱物之厚度小於錫者，則內沈澱 物通常是在至玻璃帶2之方向中游動，這會促使粒子形成。 形成氣之氧分壓値較玻璃者還低，第6圖中所示之極限 曲線3 0適用於對形成氣之最小需求量。 錫池1之品質及形成氣8之品質應持續地就氧含量來進 行監視，較佳是在多個位置（但特別是在熱端處）進行監 視，該處亦會有氧氣進入或發生經常性之干擾。 此處所示之想法是在浮動盆=氣相+Sn (錫）相+玻璃相 鲁 中草擬一種至氧平衡之第一入口。這些相位之間之更換是 以輸送方式來控制，在玻璃中主要以擴散方式來控制，錫 中則重疊著薄片式之對流程序，玻璃中主要是穩當之湍流。 利用第6圖中所草擬之程序視窗，則可首次以不平常之 方式顯示對該錫池之品質需求。利用氧分壓p〇2之較容易 到達之値（相對於實際上不可直接測量之氧含量），則吾 人可具有所需之控制値，在熔融度較高之玻璃中，封閉式 -12- 200401754 系統之P〇2極限値至開放式系統之極限曲線所需之距離通 常會大大地增力□。 . 非鹼性玻璃在控制該形成氣時因此需要一較高之耗費， 此乃因所侵入之相同數量之氧會造成錫品質之不相同之危 害’甚至造成局熔融度玻璃之負載。 此處所述之原理適用於所有之金屬池，開放式及封閉式 系統所需之熱力學上之極限溶解度因此並不相同。若缺乏 某些參考値，則可依據先前所述之實施例由實驗測定（EMK 測定，請參閱先前Fischer及Janke所著之文獻）來得到所 肇 需之極限曲線。 錫之淨化或一般金屬池1 0之淨化可藉由金屬熔液1與含 氫之氣體直接相接觸來達成。爲了提高該淨化功率，則須 較大之交換面積。亦可使用氣泡，由於移動之氣泡所造成 之機械式干擾，則只有浮動池外部之氣泡才有意義。由於 池表面在其交換作用中會受限，因此需要另一氫氣源（特 別是在玻璃帶2下方）。氫之無氣泡之純擴散發出現象在 至氫通行之壁材料之邊界面上已爲人所知。除了貴重之防 · 火金屬銥及銶之外，亦可使用薄壁之鎢或鈮（高的氫滲透 性）。 一種相對應之導管系統7在第2圖之金屬池1 〇中亦安裝 在玻璃帶下方。使用一種形成氣或純氫Η 2做爲沖洗氣。須 安裝該導管系統7，以防止一種至接地電位（例如，浮動 池之外殼等等）之電性接觸作用。因此在管/錫池之邊界 面上測量電位是可能的，其作爲製程上之控制用。 -13- 200401754 在已知之溫度時若管/錫壁之電位以成份恆定之氣體廣 泛地藉由導管系統7之穩定地沖洗來調整，則emK測定時 ' 主要之需求是一種參考電極4。與金屬池1〇中所浸入之貴 金屬測量電極3 · 1或3.2 (由Pt或Re或lr所構成）一起時 可局部性地決定金屬池1 0之氧含量且進行控制。使用Z r〇2 參考電極4不是絕對必要。第1，2圖中另顯示一種加熱器 5 ( SiC)，底唇6及玻璃熔液用之入口，其包含一種入口 唇9.1及一種可調之入口元件9.2。 利用上述之實施例，則氧含量之控制及調整用之全部元 肇 件都可設定在金屬池1 0 (特別是錫池）中。特別是最初與 製程有關之極限値，其與可輕易測量之控制値之結合以及 電化學測量鏈，池之淨化方式等都可設定。 圖示簡單說明： 第1圖 浮法玻璃製造用之配置之俯視圖。 第2圖 係第1圖之配置之部份切面之側視圖。 第3圖 先前技藝中已爲人所知之相位圖。 第4至6圖說明本發明所用之其它相位圖。 鲁 主要元件之對照表 1 金 屬 熔 液 2 玻 璃 帶 3.1,3.2 貝 金 屬 測量電極 4 參 考 電 極 5 加 熱 器 6 底 唇 7 導 管 系 統 8 形 成 氣 9.1 入 □ 唇 9.2 入 □ 元 件 10 金 屬 熔 液Find out in Wiirzburg. Oxidation of metals or tin is still not prevented by the determination of the oxygen content of the fluid metal or tin. The method described in US 6 094942 described at the beginning of this article can reduce the amount of dissolved oxygen in the fluid tin, but the disadvantage is that hydrogen bubbles will cause glass defects (open air bubbles on the lower side of the glass). When the hydrogen bubbles reach the glass ribbon Down. The above-mentioned disadvantages can be avoided by using "the oxygen concentration is affected by an appropriate ®" described in the first scope of the patent application. Other advantageous measures for improving the process of the float glass are described in the method of the scope of patent application No. 2 in which the oxygen content of the metal pool is along the temperature gradient from the hot end to the cold end by a simple oxygen partial pressure. The measurement can be measured in the molten metal or in a forming gas, and when a positive deviation occurs, it is respectively corrected to a temperature-dependent limit that is smaller than that required for the entire thermodynamic system. 200401754 Other advantageous measures are described in item 3 to 15 of the scope of the patent application. By measuring and controlling the oxygen content of the fluid tin in the floating pool, the oxygen in the fluid tin will not exceed oxygen at the ordinary temperature in the floating pool. It has a saturated concentration and therefore does not form tin oxide. This method includes some controllable tritium, electrochemical measurement chain (Chain), process-related limit tritium, and the purification method of fluid tin. (IV) Embodiments The present invention will be described in detail below with reference to the drawings. Fluid tin has a particularly high affinity for oxygen, allowing the tiniest amount of oxygen to form tin oxide. As long as the corresponding limit is not exceeded, oxygen is uniformly dissolved in the tin. The dissolution of oxygen is closely related to the temperature and is clearly expressed as a phase diagram in the form of log [p〇2] = f (T) in Fig. 3. From Figure 3 (Curve 20), it can be known that when the temperature of a typical floating bath is greater than 600 ° C, the presence of oxygen-containing fluid tin is determined by the oxygen partial pressure of less than 10-24 bar (600 ° C) or less than 10-1 1 Bar (1 200 ° C). The oxygen partial pressure p02 represents the binding force of the fluid tin to dissolved oxygen. This change in force can be more than an order of magnitude here. According to WA Faischer, D. Janke Metallurgische Elektr ochemmie, Diisseldorf 19 7 5 log {p〇2 (SnlSn〇2)} = (558306-189.6 · T / K) /2.303-RT) In addition, curve 21 shows solubility. The maximum amount of oxygen is also exponentially related to tin temperature. In the general temperature range, the identifiable oxygen content changes from a maximum of three orders of magnitude to four orders of magnitude and almost reaches 200,401,754 at 1 200 ° C 1%: log {C〇2 (SnlSn〇2)} = 3.45- 493 7 / ding (T in k). If the limit solubility moves to a lower oxygen partial pressure at a constant temperature, the equilibrium amount of dissolved oxygen decreases exponentially. In the floating cell used in the manufacture of borosilicate flat glass, there is a local p02 measurement at the hot end of the floating cell (10) (please compare Figures 1 and 2), which can be seen from Figure 4. Chu see. The partial pressure of oxygen must be measured in the forming gas (measurement points 25, 27), and the partial pressure of oxygen must also be measured in the fluid tin (measurement points 24, 26). Figure 4 contains two pairs of measurement points, of which the lower oxygen partial pressure 値 p02 is typically used to set this process normally. Since the formation gas is used to protect and purify the tin pool 10, the corresponding partial pressures are smaller than the partial pressures of tin, respectively. This is sufficient for both measurement pairs. It must be noted that when oxygen does not invade abnormally through the arched hole, it will continuously bring oxygen through glass (its partial pressure of oxygen is between 10-3 bar and 0.1 bar), which can be Replaced on the tin interface. The required purification is carried out by forming a gas atmosphere, which is achieved in a consistent manner through the surface of a tin pool that is not covered by glass. ® The oxygen partial pressure 形成 of the forming gas is defined by the molecular ratio (ratio) Η :: !! ”(N2 is inert gas and is used here only to dilute the reactive species). According to the aforementioned literature (Fisher, Janke), the water content of the formed gas is suitable for the following formula: log {PH2〇 / pH2} =: log {K (T) + (l / 2) log {p〇2} where 10 g {K} = 1 3000 / T-2.971 (T is represented by K) Calculate the corresponding water content (total hydrogen content is expressed as% -10- 200401754 components) for the above two measurement points. 23 In the respective hydrogen / water ratio (rati 0), the deduced relationship of the partial pressure of oxygen with respect to the temperature in the forming gas is additionally indicated. From the data in Figure 4, it can be known that the limit 値 when forming Sn02 is not exceeded. But Figure 4 is a purely thermodynamic consideration. It starts with a pure measurement of locality and the prerequisite is that the locality is usually the same as the balance of globality. This is the condition of an open system. However, the current status of this program is characterized by other overall boundary conditions: the individual volume elements of fluid tin (which have almost a fixed gas content) are transported in a convective manner between regions of different temperatures. 'This is more suitable for closure Conditions of the system. In particular, the volumetric elements of tin containing oxygen rapidly dragged from hotter regions to colder regions due to the strong surface flow. This applies especially to the glass-like (and more oxygen-rich) tin layer under the glass ribbon 2. For unusual results in the current process, additional attention must be paid to the absolute content of oxygen dissolved in tin. The calculated 値 is shown in Figure 5 as points 28 and 29. Therefore, it must be considered that the following relationship is suitable in the existence zone of fluid tin under isothermal conditions: [d log p〇2 / d log C〇2] t = 2. · As far as the two survey points mentioned above are concerned, a great difference is now formed. At 1 100 ° C, the two hydrazones are clearly below the limit solubility of about 0.8%. Now, if the thermal volume element is moved to a lower temperature as a closed system in concept, the limit solubility there is reached at about 7 70 ° C. This situation in the second case reaches the lowest floating level. It can still be reliably removed at a cell temperature of 600 ° C. In the case of the table, undesired spontaneous precipitation of S η 02 is caused in the cold region, but not in the first case. -11-200401754 It is important to adopt this closed system, when tin is covered with glass ribbon 2, it can prevent the dissolved oxygen from reactively interchange with the forming gas 8. The above ideas can also be reversed. · At higher temperatures, the maximum allowable oxygen partial pressure of fluid tin p0 2 must be 600 ° C under the unrestricted process conditions and will not exceed 0.006 of the allowable oxygen amount %. Fig. 6 takes the form of a p02 (Snl0.006% 〇2) curve 30 as a response. The program window of curve 30 formed by the combination of P02-T can exclude the precipitation of tin oxide inside, and each program point on it hides the danger of increased glass defects on the phase boundary (glass / tin). 0 As the thickness of the tin oxide (SnO2) precipitate is smaller than that of the tin, the internal precipitate usually swims in the direction to the glass ribbon 2, which will promote the formation of particles. The oxygen partial pressure 値 of the forming gas is lower than that of the glass. The limit curve 30 shown in Fig. 6 is suitable for the minimum demand for the forming gas. The quality of the tin pool 1 and the quality of the forming gas 8 should be continuously monitored for oxygen content, preferably at multiple locations (but especially at the hot end), where oxygen will also enter or occur frequently Sexual interference. The idea shown here is to draft a first entrance to the oxygen balance in the floating basin = gas phase + Sn (tin) phase + glass phase. The change between these phases is controlled by the conveying method, which is mainly controlled by the diffusion method in the glass, and the laminar convection program is superimposed in the tin. The glass is mainly stable turbulence. Using the program window drafted in Figure 6, the quality requirements for the tin pool can be displayed in an unusual way for the first time. Utilizing the more easily reachable plutonium of oxygen partial pressure p02 (compared to the oxygen content which can not be directly measured actually), we can have the required control plutonium, in the glass with higher melting degree, closed -12- 200401754 The distance from the P02 limit of a system to the limit curve of an open system usually increases the force greatly. Non-alkaline glass requires a relatively high cost in controlling the formation gas. This is because the same amount of oxygen invaded will cause different harms to the tin quality, and even cause the load of the locally molten glass. The principles described here apply to all metal cells. The thermodynamic limit solubility required for open and closed systems is therefore not the same. If some references are lacking, the required limit curve can be obtained by experimental determination (EMK measurement, see previous literature by Fischer and Janke) according to the previously described examples. The purification of tin or the purification of general metal pool 10 can be achieved by direct contact between metal melt 1 and hydrogen-containing gas. In order to increase the purification power, a larger exchange area is required. Bubbles can also be used. Due to the mechanical interference caused by moving bubbles, only the bubbles outside the floating pond are meaningful. Since the surface of the cell is limited in its exchange, another source of hydrogen is required (especially under glass ribbon 2). The phenomenon of pure diffusion of hydrogen without bubbles is known on the boundary surface of the wall material to which hydrogen passes. In addition to the precious anti-fire metals iridium and osmium, thin-walled tungsten or niobium (high hydrogen permeability) can also be used. A corresponding conduit system 7 is also installed under the glass ribbon in the metal pool 10 of FIG. 2. Use a forming gas or pure hydrogen Krypton 2 as the flushing gas. The conduit system 7 must be installed to prevent an electrical contact to ground potential (for example, the housing of a floating cell, etc.). Therefore, it is possible to measure the potential on the boundary surface of the tube / tin pool, which is used as a control in the process. -13- 200401754 If the potential of the tube / tin wall is widely adjusted by a stable flushing of the duct system 7 with a gas of constant composition at a known temperature, the main requirement for emK measurement is a reference electrode 4. With the precious metal measuring electrode 3 · 1 or 3.2 (consisting of Pt or Re or lr) immersed in the metal pool 10, the oxygen content of the metal pool 10 can be locally determined and controlled. It is not absolutely necessary to use the ZrO2 reference electrode 4. Figures 1 and 2 show a heater 5 (SiC), a bottom lip 6 and an inlet for glass melt, which includes an inlet lip 9.1 and an adjustable inlet element 9.2. With the above-mentioned embodiment, all the elements for controlling and adjusting the oxygen content can be set in the metal pool 10 (especially the tin pool). In particular, the limit 値 related to the process at first, its combination with the control 値 that can be easily measured, the electrochemical measurement chain, and the purification method of the cell can be set. Brief description of the figure: Figure 1 Top view of the configuration of float glass manufacturing. Figure 2 is a side view of part of the configuration of Figure 1. Figure 3 Phase diagrams known in the prior art. Figures 4 to 6 illustrate other phase diagrams used in the present invention. Comparison table of the main components of Lu 1 Metal melt 2 Glass ribbon 3.1, 3.2 Metal measuring electrode 4 Reference electrode 5 Heater 6 Bottom lip 7 Guide tube system 8 Forming gas 9.1 into □ Lip 9.2 into □ Element 10 Metal melt