Abstract: There are provided a conduit structure for molten glass, a vacuum degassing apparatus using the conduit structure, and a process for vacuum-degassing molten glass by use of the vacuum degassing apparatus, wherein without using a cooling system, solid thermal insulating materials constituting a backup for the conduit are prevented from being corroded by molten glass oozing out of a joint between adjacent fused cast refractories constituting the conduit, and wherein production cost is reduced.

Abstract: To provide a vacuum-degassing method and a vacuum degassing apparatus excellent in the effect of vacuum-degassing molten glass, more specifically, a method for vacuum-degassing molten glass and a vacuum degassing apparatus, capable of effectively suppressing formation of reboil bubbles. A method for vacuum-degassing molten glass, which comprises melting glass materials to be silicate glass and passing the resulting molten glass in a flow passage in a vacuum degassing vessel, the interior of which is maintained in a reduced pressure state, to vacuum-degas the molten glass, wherein vacuum-degassing is carried out under conditions satisfying the following formula (1) at a bottom portion of the vacuum degassing vessel: SS=pSO2/Pabs <2.0??(1) wherein SS is the supersaturation degree of SO2 in the molten glass, pSO2 is the partial pressure (Pa) of SO2, and Pabs is the pressure (Pa) at the bottom portion of the glass flow passage of the vacuum degassing vessel.

Abstract: There are provided a conduit structure for molten glass, a vacuum degassing apparatus using the conduit structure, and a process for vacuum-degassing molten glass by use of the vacuum degassing apparatus, wherein without using a cooling system, solid thermal insulating materials constituting a backup for the conduit are prevented from being corroded by molten glass oozing out of a joint between adjacent fused cast refractories constituting the conduit, and wherein production cost is reduced.

Abstract: To provide a vacuum-degassing method and a vacuum degassing apparatus excellent in the effect of vacuum-degassing molten glass, more specifically, a method for vacuum-degassing molten glass and a vacuum degassing apparatus, capable of effectively suppressing formation of reboil bubbles. A method for vacuum-degassing molten glass, which comprises melting glass materials to be silicate glass and passing the resulting molten glass in a flow passage in a vacuum degassing vessel, the interior of which is maintained in a reduced pressure state, to vacuum-degas the molten glass, wherein vacuum-degassing is carried out under conditions satisfying the following formula (1) at a bottom portion of the vacuum degassing vessel: SS=pSO2/Pabs<2.0??(1) wherein SS is the supersaturation degree of SO2 in the molten glass, pSO2 is the partial pressure (Pa) of SO2, and Pabs is the pressure (Pa) at the bottom portion of the glass flow passage of the vacuum degassing vessel.

Abstract: A process for producing a float bath bottom refractory brick which can suppress a reaction with Na2O from glass at the surface of the refractory brick and thereby prevent flaking phenomena, which process comprises adding a potassium compound to a clayey material comprising from 30 to 45 mass % of Al2O3 and from 50 to 65 mass % of SiO2 and having a Na2O content of at most 1 mass %, so that the K2O content in the float bath bottom refractory brick to be produced would be from 2 to 4 mass %; and a refractory brick useful for a float bath bottom for production of plate glass by a float process.

Abstract: It is to provide a process for producing a float bath bottom refractory brick which can suppress a reaction with Na2O from glass at the surface of the refractory brick and thereby prevents flaking phenomena, as a refractory brick to be used for a float bath bottom for production of plate glass by float process. A process for producing a float bath bottom refractory brick using a clayey material comprising from 30 to 45 mass % of Al2O3 and from 50 to 65 mass % of SiO2 and having a Na2O content of at most 1 mass %, wherein a potassium compound is added so that the K2O content in the float bath bottom refractory brick to be produced would be from 2 to 4 mass %.