Patent ID: 8720229

Claim:
A vacuum degassing apparatus comprising: a vacuum degassing vessel providing a molten glass flow path of a molten glass, the molten glass flow path having a first portion, a wide portion and a second portion; an uprising pipe connected with the vacuum degassing vessel in the first portion; and a downfalling pipe connected with the vacuum degassing vessel in the second portion, wherein the vacuum degassing vessel provides the molten glass flow path having a breadth W 1 and a length L 1 in the wide portion, which satisfy that a proportion W 1 /L 1 is at least 0.2, the first portion has a breadth W 2 in a portion connected with the uprising pipe, the second portion has a breadth W 3 in a portion connected with the downfalling pipe, the breadth W 2 and the breadth W 3 are narrower than the breadth W 1 in the wide portion, the vacuum degassing vessel is configured such that a position of a bottom of the molten glass flow path in the portion connected with the uprising pipe and a position of a bottom of the molten glass flow path in the portion connected with the downfalling pipe are lower than a position of a bottom of the molten glass flow path in the wide portion, the breadth W 1 in the wide portion is at least 1,000 mm, and the vacuum degassing apparatus provides a throughput of 200 tons/day or more.