A study of the behavior of volatiles in the float process

The float process is one of the most widely employed methods for flat glass manufacturing. Tin speck on the top surface of the glass sheet is one of the specific defects for the float process, caused by droplets derived from volatiles from the molten tin surface. That is, the volatilized materials from the tin surface are advected and diffused in the gas flow and finally drop onto the glass ribbon. The gas flow is complex and difficult to understand, because it is driven not only by advection but also buoyancy convection. We have studied the behavior of volatiles by carrying out the computational simulation of the gas flow and the mass transfer for the first time. Remarkably the mechanism and the characteristic of the behavior of volatiles have been revealed. The technique can be used to optimize the operation and to design float baths in order to minimize tin speck.