Gasdispergierung in Flüssigkeiten durch Düsen bei hohen Durchsätzen

Siemes, W.; Günther, Kerstin

doi:10.1002/cite.330280603

“…Die Blasenschwarme wurden in verschiedener Hohe iiber der Gasverteilerplatte photographiert und die Filmnegative ausgewertet. Die Aufnahmetechnik entsprach weitgehend der von W. Siemes und K. Gunther in einer fruheren Arbeit[2] verwendeten. Ferner wurde aus den Ruhe-und den Expansionshohen der Blasensaule ihr relativer Fliissigkeitsgehalt bestimmt.…”

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Größenverteilung der Gasblasen in Blasensäulen. Teil I: Einflüsse von Flüssigkeitsviscosität und Säuleninnendruck

Kölbel

¹

,

Borchers

²

,

Langemann

³

1961

Chemie Ingenieur Technik

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Untersucht wurde der Einfluß des Gasdurchsatzes, des Säulendurchmessers, der Porenweite der Gasverteilerplatte, des Abstandes von der Gasverteilerplatte sowie der Viscosität der Blasensäulenflüssigkeit auf die Blasengrößenverteilung und die Blasenaufstiegsgeschwindigkeit an dem System Luft/Zuckerlösung ferner der Einfluß des Gasdurchsatzes, des Säuleninnendruckes und der Aufnahmehöhe an dem System Luft/Wasser. Dabei zeigte sich, daß die spezifische Oberfläche der Gasblasen mit Ansteigen des Gasdurchsatzes, der Viscosität der Flüssigkeit, des Druckes, der Porenweite der Gasverteilerplatte und des Abstandes von dieser sowie mit Abnahme des Säulendurchmessers sinkt.

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“…As can be seen from Eq. [9] the velocity is observed to increase with increasing bubble size and decreasing bubble spacing, as it should if proximity or wake phenomenon significantly affect the bubble velocity. The only slight increase in the amount of data successfully described by the model (i.e., from 87.7 to 88.0 pct) is a reflection of the fact that the bubble spacing alone accounts for only 14.7 pct of the explained data, whereas the bubble diameter alone accounts for 93.6 pct of the data.…”

Section: Gas Bubble Velocities Under Dynamic Conditionsmentioning

confidence: 88%

Characterization of gas bubbles injected into molten metals under laminar flow conditions

Andreini

¹

,

Foster

²

,

Callen

³

1977

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Velocity and volume measurements of gas bubbles injected into liquid metals under laminar flow conditions (at the orifice) have been achieved. A novel experimental approach utilizing noises generated by bubbles was used to collect the necessary data. Argon gas was bubbled through tin, lead, and copper melts, and gas bubble formation frequencies (and hence bubble sizes) were determined. It was found that the bubble size generated for a particular orifice diameter was dependent upon the magnitudes of the orifice Froude and Weber numbers. Maximum formation frequencies increased slightly with decreasing orifice diameter, and the transition point from varying to constant frequency occurred at an orifice Weber number of approximately 0.44. Velocities of gas bubbles rising through the metals were greater than those previously reported for studies in which only one bubble was in the melt at any time. Effective drag coefficients of the rising bubbles were found to agree with data previously generated in aqueous systems.

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“…[9] the velocity is observed to increase with increasing bubble size and decreasing bubble spacing, as it should if proximity or wake phenomenon significantly affect the bubble velocity. The only slight increase in the amount of data successfully described by the model (i.e., from 87.7 to 88.0 pct) is a reflection of the fact that the bubble spacing alone accounts for only 14.7 pct of the explained data, whereas the bubble diameter alone accounts for 93.6 pct of the data.…”

Section: Gas Bubble Velocities Under Dynamic Conditionsmentioning

confidence: 88%

“…For velocity as a function of bubble size only, the expression v b = 29.69(db) TM cm s -~ [8] was found to best describe the data. Considering both bubble size and proximity, the relation v b = 27.88(db) ~176 (Sb) "~176 cm s -1 [9] was determined to be satisfactory. The bubble spacing, Sb, was taken as the center to center distance of the rising bubbles.…”

Section: Gas Bubble Velocities Under Dynamic Conditionsmentioning

confidence: 96%

Characterization of gas bubbles injected into molten metals under laminar flow conditions

Andreini

¹

,

Foster

²

,

Callen

³

1977

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Velocity and volume measurements of gas bubbles injected into liquid metals under laminar flow conditions (at the orifice) have been achieved. A novel experimental approach utilizing noises generated by bubbles was used to collect the necessary data. Argon gas was bubbled through tin, lead, and copper melts, and gas bubble formation frequencies (and hence bubble sizes) were determined. It was found that the bubble size generated for a particular orifice diameter was dependent upon the magnitudes of the orifice Froude and Weber numbers. Maximum formation frequencies increased slightly with decreasing orifice diameter, and the transition point from varying to constant frequency occurred at an orifice Weber number of approximately 0.44. Velocities of gas bubbles rising through the metals were greater than those previously reported for studies in which only one bubble was in the melt at any time. Effective drag coefficients of the rising bubbles were found to agree with data previously generated in aqueous systems.GAS bubble-liquid metal interactions are important in numerous refining processes such as the deoxidation of copper, degassing of aluminum, and decarburization of high alloy and stainless steels. Submerged lets which produce large dispersions of small bubbles are used in the deoxidation of copper and steel decarburization. The basic action of the submerged jet in which large bubbles moving away from the orifice "explode" into many smaller bubbles after traveling a short distance has been qualitatively appreciated for quite some time, and the high specific interracial area of the gas-liquid dispersion is recognized as being responsible for the relatively high efficiencies of these processes. Much less violent conditions are mainrained in aluminum degassing operations where nitrogen or nitrogen-chlorine mixtures are introduced virtually as single bubbles.In both types of systems many of the basic parameters have not yet been well defined. In single bubble processes these parameters include bubble size and residence time in the melt. With respect to jet phenomena, the residence time of the gas and the specific interracial area of the dispersion are very important in determining the efficiency of gas utilization, the extent of splashing, and the rate of refractory erosion.Bubbles generate distinct noises as they break from a submerged orifice and burst the surface of the liquid. The break at the orifice consists of relatively low frequency noise components while the sound generated by bursting through the surface is relatively high frequency. Because of this difference, an acoustic technique has been developed which enables data on gas bubble formation frequency at a submerged orifice together with velocity measurements to be realized in molten metals. Parameters which influence the size of bubbles generated at orifices and bubble velocities under dynamic conditions (where the bubbles are formed continuously at an orifice) were determined. The acoustical technique developed provided a means for making comparis...

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Gasdispergierung in Flüssigkeiten durch Düsen bei hohen Durchsätzen

Abstract: AuswertungsmethodeDie Photographien zeigten Blasen verschiedenster GroRe und Gestalt, oft einander uberdeckend, Bild 2 bis 9.Chemie-1ng.-Tech.28. Jahrg. 1956 / Nr. 6

Cited by 19 publications

References 4 publications

Größenverteilung der Gasblasen in Blasensäulen. Teil I: Einflüsse von Flüssigkeitsviscosität und Säuleninnendruck

Größenverteilung der Gasblasen in Blasensäulen. Teil I: Einflüsse von Flüssigkeitsviscosität und Säuleninnendruck

Characterization of gas bubbles injected into molten metals under laminar flow conditions

Characterization of gas bubbles injected into molten metals under laminar flow conditions

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