Influence of spout lip set-height on flow behavior during the glass float process

Abstract

One of the most widely employed procedures for flat glass manufacture is float process proposed by Pilkington. Nowadays, there is great demand for thinner float glass of high optical quality. The most important stage of float process is the glass forming in tin bath. In this study, the ANSYS Fluent 14.0 software is adopted to develop a multiphase numerical model and simulate the flow phenomena of molten glass when it is spouted over a lip onto the tin bath under protective atmosphere. The influence of spout lip set-height on flow behavior of molten glass and tin at tin bath entrance is investigated. The results of 2D simulation indicate that the velocity at the vertex of spout lip, the depth where glass dips into tin bath as well as wetback flow increase with the set-height. From results of 3D simulation, the expansion of glass ribbon and velocity gradient along lateral direction of tin bath occurs as molten glass floats on molten tin. The velocity components of Vy and Vx of wetback flow are significant at the edge while are extremely low near symmetry plane. The larger velocity components of Vy and Vx of wetback flow are achieved with increase of spout lip set-height, which would facilitate more glass containing impurities to flow towards the edge of glass ribbon and improve the glass forming quality. The simulation results are supposed to guide the optimization design of spout lip.