Apparatus and method for producing glass ribbons

An apparatus for producing thin glass ribbons from a molten glass, the apparatus comprising:

• a drawing tank having a manifold pipe, a wall, and a nozzle opening through the wall, the manifold pipe having an upper portion with a cylindrical cross-section that is transverse to a drawing direction of the thin glass ribbons and along a longitudinal extension of the nozzle opening, the nozzle opening being configured to allow the molten glass to exit the drawing tank and produce the thin glass ribbons with a thickness up to 3000 μm;
• a direct heater having a heating circuit and a power source, the heating circuit defining a first heating zone to heat the drawing tank, the power source operatively connected to the heating circuit, the heating circuit having power connections that connect the heating circuit to the manifold pipe so that a current from the power source flows through a current-carrying portion of the manifold pipe to heat the manifold pipe, the power connections comprising a pair of collars fitted to the upper portion of the manifold pipe;
• and
• an indirect heater having a heating element arranged around the drawing tank and defining a second heating zone to heat the drawing tank, wherein the apparatus is configured so that more than 50% of a total heating power output is provided by the indirect heater and is configured so that the indirect heater is positioned to heat at least the drawing tank at the nozzle opening.

An apparatus for producing thin glass ribbons from a molten glass, the apparatus comprising:

• a drawing tank having a manifold pipe, a wall, and a nozzle opening through the wall, the manifold pipe having an upper portion with a cylindrical cross-section that is transverse to a drawing direction of the thin glass ribbons and along a longitudinal extension of the nozzle opening, the nozzle opening being configured to allow the molten glass to exit the drawing tank and produce the thin glass ribbons with a thickness up to 3000 μm;
• a direct heater having a heating circuit and a power source, the heating circuit defining a first heating zone to heat the drawing tank, the power source operatively connected to the heating circuit, the heating circuit having power connections that connect the heating circuit to the manifold pipe so that a current from the power source flows through a current-carrying portion of the manifold pipe to heat the manifold pipe, the power connections comprising a pair of collars fitted to the upper portion of the manifold pipe;
• an indirect heater having a heating element defining a second heating zone to heat the drawing tank;
• and
• a plurality of temperature measurement points connected to the drawing tank, wherein at least two of the plurality of temperature measurement points are positively connected to the drawing tank.