Effect of roof-mounted burners on boron evaporation in fiber glass furnaces
This internal study was carried out to identify the effect of roof-mounted burners on boron evaporation in an Oxy-Fuel fired fibre glass furnace. Especially the effect on corrosion of the refractory material was of interessed.
Based on furnace and operation data of a former project (the furnace is already shut down), a base case was set up. Based on this base case different arrangements of roof-mounted burners were implemented and simulated.
Specific attention was paid to the simulation of boron evaporation from the batch. The simulation of the Oxy-Fuel combustion and the calculation of the result heat transfer from the combustion space to the glass. Both the combustion space and the glass melt was modeled to be able to simulate the changes melting behaviour, expecially the shape and thickness of the batch blancket.
Because a precise simualtion of the Oxy-Fuel combustion was not important, standard turbulence-chemistry-interation model were used. Potential issues are not a conhsequence of the flame tempeture and species composition but by the resulting transport of evaporations by the flue gas flow. The differences concerning the flow pattern was in this case insignificant.
The comparision of the base case and the variations showed that is difficult to prevent an increased of corrosion using roof-mounted burners. The reason was minor a question of flame velocities, than a question of the resulting strong mixing of flue gases containing high boron evaporations and their contact with the refractory surfaces.
This studied rised strong doubt that roof-mounted burners can be fired at boron containing batches without an increase in refractory corrosion.