Abstract: A glass melt production apparatus, which comprises a melting vessel, a vacuum degassing apparatus, a first conducting pipe structure connecting the melting vessel and the vacuum degassing apparatus, and a second conducting pipe structure to introduce a glass melt to a forming means, provided downstream the vacuum degassing apparatus; the vacuum degassing apparatus having an uprising pipe through which the glass melt from the melting vessel ascends, a vacuum degassing vessel, and a downfalling pipe through which the glass melt from the vacuum degassing vessel descends; the flow path of the glass melt in the uprising pipe, the vacuum degassing vessel and the downfalling pipe being made of a refractory material; the first conducting pipe structure having an upstream pit to supply the glass melt to the uprising pipe; and the second conducting pipe structure having a downstream pit containing the glass melt from the downfalling pipe; the glass melt production apparatus further comprising a third conducting pipe st

Abstract: To facilitate a preheating operation in a vacuum degassing apparatus having a flow path of a glass melt in an uprising pipe, a vacuum degassing vessel and a downfalling pipe constituted by a refractory material. Flow of a glass melt G between a melting vessel 100 and an upstream pit 210 of a first conducting pipe structure connected to a vacuum degassing vessel 320 is shut off, and in a state where the flow of the glass melt G in a by-pass 500 for the glass melt G is shut off by a first closing means 220, a combustion gas from preheating burners 530, 540 is introduced to the by-pass 500 to preheat the flow path of the glass melt G in an uprising pipe 330, the vacuum degassing vessel 320 and a downfalling pipe 340.

Abstract: The present invention is to provide a molten glass producing apparatus realizing simultaneously the production of a glass article of high quality and save-energy in producing molten glass, a molten glass producing method employing the molten glass producing apparatus and a method for producing a glass article. In the molten glass producing apparatus having a vacuum degassing apparatus, the melting tank is provided with a separating means for separating the area for circulating the molten glass in the melting tank into an upstream circulation flow and a downstream circulation flow, the distance from the separating means to the downstream end of the molten glass flow path in the melting tank is from 0.1 LE to 0.