A glass rod includes: a glass including a glass composition, wherein the total relative length variation of the semi-major axis tlv.sub.major is determined as an absolute difference between (a) a smallest semi-major axis length I.sub.major(n) and (b) a largest semi-major axis length I.sub.major(n), normalized by the average semi-major axis length l.sub.major(a); wherein the 50 equidistant cross-sections are positioned along the length l.sub.rod of the glass rod, starting at a position of 0.01*l.sub.rod as a first position and employing a plurality of additive increments of 0.02*l.sub.rod for each subsequent position; wherein the relative local area variation lav is determined as an absolute difference between (c) a cross-sectional area that has the largest semi-major axis length I.sub.major(n) and (d) an average value of the cross-sectional areas, normalized by an average value of the cross-sectional areas; wherein the quality index (tlv.sub.major+lav) is 0.090 or less.

A glass manufacturing apparatus comprises at least one nozzle facing a conduit and extending transverse to a travel path defined by the conduit. The at least one nozzle is configured to cool molten material within the interior of the conduit with a stream of cooling fluid forced against an exterior of the conduit along a cooling axis extending transverse to the travel path defined by the conduit. In further examples, methods of processing molten material includes cooling the molten material within an interior of a conduit by forcing a stream of cooling fluid against an exterior of the conduit along a cooling axis extending transverse to a travel path defined by the conduit.

A glass manufacturing apparatus comprises at least one nozzle facing a conduit and extending transverse to a travel path defined by the conduit. The at least one nozzle is configured to cool molten material within the interior of the conduit with a stream of cooling fluid forced against an exterior of the conduit along a cooling axis extending transverse to the travel path defined by the conduit. In further examples, methods of processing molten material includes cooling the molten material within an interior of a conduit by forcing a stream of cooling fluid against an exterior of the conduit along a cooling axis extending transverse to a travel path defined by the conduit.

An apparatus and method of refining molten glass are disclosed. An upstream vessel contains molten glass, a downstream vessel is arranged downstream of the upstream vessel, and vacuum refining vessels are located between the upstream vessel and the downstream vessel and are in separate, alternating fluid communication with the upstream vessel and in separate, alternating fluid communication with the downstream vessel.

A furnace system includes a mixing chamber that receives separate streams of raw material and cullet mix and discharges a combined stream. The mixing chamber tapers from an inlet end to an outlet end. One inlet in the inlet end is configured to receive one of the material and mix and is aligned with an outlet in the outlet end along a vertical axis. Another inlet is configured to receive the other of the material and mix and is offset from the outlet relative to the vertical axis such the material or mix is deposited on a sidewall of the tapered chamber before reaching the outlet. A charger receives the combined stream from the mixing chamber and discharges the mixture into a molten bath in a furnace. A duct system may be used to mix exhaust from the furnace with exhaust from the mixing chamber and charger.

An apparatus and a method for producing glass products from a glass melt, avoiding bubble formation, are disclosed, wherein the apparatus includes a crucible and an internally component for processing the glass melt, and wherein, for heating the glass melt, the apparatus comprises an AC generator which energizes the crucible or stirring crucible via electrical connection elements. The component or stirring system is connected via a current-limiting choke having a variable impedance with the power supply elements. The impedance of the current-limiting choke is adjusted so that a AC density existing in the glass melt lies between a lower limit value and an upper limit value. By means of a choke and by adjusting the impedance it can be achieved that the AC load of the system can be minimized and that simultaneously the water decomposition reaction at the precious metal surfaces can positively be influenced.

A method for manufacturing glass, including the steps of heat-melting a raw material for producing glass by using a melting furnace having a plurality of gas flow paths while the raw material is levitated from the melting furnace by a gas ejected from the gas flow paths, and performing cooling so as to produce glass, wherein the melting furnace includes a recess portion, at least one first gas flow path configured to eject the gas in the vertical direction into the recess portion, a plurality of second gas flow paths configured to eject the gas in the direction toward the center axis of the melting furnace into the recess portion, the raw material is heat-melted while the raw material is levitated by the gas ejected from the first gas flow path and the gas ejected from the second gas flow paths, and the molten raw material is cooled.

One aspect is an oven including a melting crucible with a crucible wall, a solids feed with an outlet, a gas inlet and a gas outlet, wherein in the melting crucible the gas inlet is arranged below the solids feed outlet and the gas outlet is arranged at the same height as or above the solids feed outlet. One aspect further relates to a process for making a quartz glass body, including providing and introducing a bulk material selected from silicon dioxide granulate and quartz glass grain into the oven and providing a gas, making a glass melt from the bulk material, and making a quartz glass body from at least a part of the glass melt. One aspect relates to a quartz glass body obtainable by this process and a light guide, an illuminant and a formed body which are each obtainable by processing the quartz glass body further.

The present invention provides for synthesizing high optical quality multicomponent chalcogenide glasses without refractive index perturbations due to striae, phase separation or crystal formation using a two-zone furnace and multiple fining steps. The top and bottom zones are initially heated to the same temperature, and then a temperature gradient is created between the top zone and the bottom zone. The fining and cooling phase is divided into multiple steps with multiple temperature holds.

Methods of processing molten material comprising the step (I) of flowing molten material through an interior of a conduit from a first station to a second station of a glass manufacturing apparatus and the step (II) of cooling the molten material within the interior of the conduit by passing a cooling fluid along an exterior of the conduit. The method further includes the step (III) of directing a travel path of the cooling fluid toward a vertical plane passing through the conduit. In further examples, a glass manufacturing apparatus comprises a first station, a second station, and a conduit configured to provide a travel path for molten material traveling from the first station to the second station. The glass manufacturing apparatus further comprises at least one baffle configured to direct a travel path of cooling fluid toward a vertical plane passing through the conduit.