Burner and method for the manufacture of synthetic quartz glass

A method for the manufacture of a synthetic quartz glass ingot using a burner comprising a main burner comprising a multi-tube assembly of a three or more tube construction including a center tube, a first enclosure tube surrounding the center tube, and a second enclosure tube surrounding the first enclosure tube, a tubular shell surrounding the multi-tube assembly, and a plurality of nozzles disposed within the tubular shell, the main burner defining a forward opening, and a double-tube assembly surrounding at least the forward opening of the main burner;

• said method comprising the steps of:
• placing the burner to face a quartz glass target mounted on a rotating support,
• feeding a silica-forming compound to the center tube, a combustion-supporting gas to the first enclosure tube and the nozzles, a combustible gas to the second enclosure tube and the tubular shell, and a combustion-supporting gas to the double-tube assembly, wherein the combustible gas fed through the tubular shell is channeled to flow about the nozzles,
• forming an oxyhydrogen flame from the combustion-supporting gas and the combustible gas for subjecting the silica-forming compound to vapor phase hydrolysis or oxidative decomposition to form silica fines,
• depositing the silica fines on the target, and simultaneously melting and vitrifying the deposited silica into quartz glass;
• wherein
• the silica-forming compound is fed to the center tube at a flow rate of 0.3 to 0.7 Nm3/hr,
• combustion-supporting gas is additionally fed to the center tube at a flow rate of 2.0 to 4.0 Nm3/hr,
• the flow rate of combustion-supporting gas through the first enclosure tube is 0.3 to 2.5 Nm3/hr
• the flow rate of combustible gas through the second enclosure tube is 12 to 15 Nm3/hr,
• the flow rate of combustible gas through the shell is 20 to 25 Nm3/hr,
• the total flow rate of combustion-supporting gas through the nozzles is 10 to 16 Nm3/hr, and
• the flow rate of combustion-supporting gas through the double-tube assembly is 2 to 5 Nm3/hr.