A model for foam formation, stability, and breakdown in glass-melting furnaces文档.pdf

Journal of Colloid and Interface Science 295 (2006) 218–229 /locate/jcis A model for foam formation, stability, and breakdown in glass-melting furnaces John van der Schaaf a,∗ , Ruud G.C. Beerkens b a Laboratory of Chemical Reactor Engineering, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands b TNO TPD, Department of Glass Technology, P.O. Box 595, 5600 AN Eindhoven, The Netherlands Received 6 August 2004; accepted 30 July 2005 Available online 2 September 2005 Abstract A dynamic model for describing the build-up and breakdown of a glass-melt foam is presented. The foam height is determined by the gas flux to the glass-melt surface and the drainage rate of the liquid lamellae between the gas bubbles. The drainage rate is determined by the average gas bubble radius and the physical properties of the glass melt: density, viscosity, surface tension, and interfacial mobility. Neither the assumption of a fully mobile nor the assumption of a fully immobile glass-melt interface describe the observed foam formation on glass melts adequately. The glass-melt interface appears partially mobile due to the presence of surface active species, e.g., sodium sulfate and silanol groups. The partial mobility can be represented by a single, glass-melt composition specific parameter ψ . The value of ψ can be estimated from gas bubble lifetime experiments under furnace con