Bubbler systems are installed for a number of reasons:
Improved glass homogeneity
Improved temperature homogeneity
To fix the hot spot
To control batch cover
The main benefit of a bubbler system is to improve homogeneity by reinforcing the natural upward currents at the hot spot which is particularly beneficial when melting coloured glasses.
A single or double row of bubblers installed across the furnace at the hot spot reinforces the vertical currents, and leads to a notable improvement in temperature homogeneity.
The number of bubbler tubes installed and the diameter of the nozzle diameter will be decided according to the furnace design, the glass to be melted and the anticipated bottom temperature.
The air pressure and flow is used to regulate the frequency and size of the bubbles, it should be noted that a reduction of molten glass viscosity (equal to a temperature increase) reduces the size of the bubbles generated and also increases their frequency.