Method for manufacturing glass ingot

A method for manufacturing a glass ingot, the method comprising:

• preparing a supply system comprising:
• a gasifier that gasifies a raw material compound comprising an organic silicon compound supplied from a supply source;
• and
• a burner that combusts the gasified raw material compound to generate SiO2;
• adding an oxygen-containing gas to the raw material compound at a plurality of addition places comprising:
• an upstream addition place located in the gasifier or on an upstream side of the gasifier;
• and
• a downstream addition place located on a downstream side of the gasifier in which locations of the raw material compound in a flow direction are different in the supply system so as to form a raw material mixture;
• and
• adding the oxygen-containing gas at the upstream addition place such that a concentration of oxygen or a concentration of the raw material compound in the raw material mixture is not in a combustible range of the raw material mixture in an outlet of the gasifier,
• wherein, at the downstream addition place, the oxygen-containing gas is added such that a ratio of a flow rate of the raw material mixture to the molar concentration of oxygen in terms of a standard state in an outlet of the burner reaches 3.0 m/s-% or less.