DE1220091B - Process for melting glass, e.g. B. Quartz glass - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

C03b

German class: 32 a - 5/00

Number: 1220091

File number: N 23185 VI b / 32 a

Filing date: May 17, 1963

Opening day: June 30, 1966

A method for melting glass is known, ζ. Β. Quartz glass, using a furnace with an outflow opening in its bottom part for the melt and burner flames, which are directed approximately horizontally over the melt pool surface, with the raw materials for the melt applied in a thin layer to the melt and fused with it.

In this known method, the raw materials which z. B. from fragments of rock crystal consist in a thin layer just above the discharge opening of the furnace onto the surface of the melt upset. In this way it is achieved that the raw materials fused with this surface are discharged directly to the discharge opening. In the case of the furnace used in this case, it comes in handy cores flow in the glass in a horizontal direction. Since the known method continues to be only a relatively small part of the enamel surface is provided with a thin layer of raw material that those parts of the melt which are close to the refractory furnace walls are practically not get caught in a flow. Wear products of these walls then almost do not become the outflow opening dissipated in the ground. By choosing a preferably simple, thin layer of raw material and in that the heat supply to the melt is directed almost horizontally over the surface of the melt pool When burner flames are removed, gas inclusions will be in the melt as it fuses of raw materials avoided. Such gas inclusions are then practically non-existent in the product, which is produced from the melt leaving the discharge opening.

Since in the known method the raw materials for the melt immediately downwards after it has melted disappear to the outlet opening in the floor, the melted raw materials do not linger in the furnace long, which is less desirable under certain circumstances.

The invention aims to provide measures by which the mean residence time of the molten Raw materials and thus also the lautering time can be increased.

In the glass melting process described above, this is achieved in that the raw materials are applied to the molten bath surface in an essentially ring-shaped zone which leaves the part of the molten bath surface above the discharge opening completely free and whose outer boundary is at a distance from the inner wall of the furnace. Here, under an essentially method for melting glass, ζ. Β.
Quartz glass

Applicant:

N. V. Philips' Gloeilampenfabrieken,

Eindhoven (Netherlands)

Representative: "

Dipl.-Ing. H. Zoepke, patent attorney,

Munich 5, Erhardtstr. 11

Named as inventor:

Willem Van der CoIk,

Johannes Feenstra,

Emmasingel, Eindhoven (Netherlands)

Claimed priority:

Netherlands of May 21, 1962 (278 694)

annular zone z. B. understood a zone which has a circular or square inner or Has outer circumference. As a result of the feed of the raw materials into this ring-shaped zone, that on the one hand the molten raw materials in this zone more or less radially to the center of the zone be discharged, whereby the mean lautering time is increased, and on the other hand, compliance with a Distance from the inner wall of the furnace contributes to the fact that arisen at the point of the inner wall Wear products are at least not discharged radially to the center of the annular zone.

The feed of the raw materials into the ring-shaped zone of the molten bath surface can take place by means of suitable insertion tools.
An expedient embodiment of this method according to the invention consists darm that the combustion gases swirl unidirectionally around a center line running through the outflow opening in the vertical direction up to a gas outlet opening provided in the top of the furnace and the raw materials fed through this outlet opening over at least part of the to to get to the melt surface distance to be covered during the fall so under the influence of the swirling gases that they fall on an annular zone of the surface of the melt. In this embodiment of the method, inserting tools of a special design for ring-shaped dosing are unnecessary, and it is

609 587/92

Claims (1)

i ZiSU USl 3 4 is sufficient that the raw materials, although they are more or less above the drawing cone 15. In contrast to the Known methods that are fed centrally via the outflow opening are therefore the molten ones to find out about part of their case in the desired- raw materials of this zone the opportunity to find out about th way so that they move in an annular a larger way to the drawing cone than Zone of the molten bath surface. 5 it for raw materials applied inside the ring A glass melting furnace with a round cross-section would be the case. The former move z. B, according to sen burner on the circumference of the burner so arranged the line shown in dashed lines (35, 36 or 37), are that the flames are one in the middle of the tub while the latter are immediately in accordance with the touching an imaginary circle is known among other things. from the route to the drawing cone marked, for example, 38 Patent specification 622 234. About the identified io. As a result of the ring-shaped feeding of the raw drawing However, there is no new process there, so that, naturally under the guided. Requirement for regular feeding again The new process is subsequently carried out on the basis of other raw materials that are removed from the side walls of the a glass melting furnace shown in the drawing outside oven explained in more detail. 15 of the annular zone and below it localized lead F i g. 1 is a vertical section through the oven, ben and so it did not get into the drawn product. Fig. 2 is a section along the line H-II of the gene. On the other hand, are in an annular Fig. 1. Zone applied raw materials according to a continuous In this example for vertical drawing of a longer section to the drawing cone or tubes made of quartz glass certain furnace a ° leads, thereby reducing the mean refining time required for the possessed a bottom part 1 in which there is an opening 3 for melted raw materials in the annular zone is still an upright part 5, is available, is larger than would be possible if several openings 7 for gas burners 9 are a simple raw material layer on the melt surface. The material of the surface facing the furnace chamber only essentially just above the drawing furnace is made on the basis of zirconium oxide. 25 cone 15 is fed. Inside the furnace there is a molten For the discharge of the combustion gases is the in Amount of glass 19. this example conical hood 11 des In the opening 3 there is a so-called pulling furnace provided with an opening 13, above which a cone 15, which is arranged in the usual way with a mandrel 17 vibrating chute 35. Is provided by the channel 35. The raw materials can be fed through this cone and then fall into a molten amount of glass to a tube 38 below the furnace. This pipe, which is preferably disposed of the drawing machine 21, is removed. Since it is double-walled and water-cooled, the cone has molybdenum parts and is also made of a heat-resistant material and extends the existing heating coil 23 made of worfram centrally through the opening 13. The pipe is, measures have been taken to avoid that the height direction can still be adjusted, which is indicated in FIG. 1 by the double arrow 39 when exposed to the ambient air of the furnace.
will. For this purpose, a sheath 25 is attached, in which one of the four burners 9 is maintained in the preferably non-oxidizing atmosphere. Cylindrical side wall 5 arranged that the If pipes have to be drawn, a non-oxidizing atmosphere is also maintained within main directions of the exiting flames tandes pipe against a concentric .mit the ring sphere by a non-oxidizing shaped zone 31 running circle 41.
Gas is supplied in the direction of the arrow noted. As a result of this arrangement affect the burner According to a known method, quartz can be used to separate the main directions, and one is created Glass produce that the heat supply to the rotating swirling gas flow 45, the upwards Surface of the melt 19 45 present in the furnace is discharged. Compared to an oven where Burner flames is removed that is almost horizontal. The main direction of the burner flames is not umgezontal are directed above the enamel surface. The bend results from the swirling of the raw materials for the melt, like small fragments of combustion gases, the advantage that the refractory Mavon Rock crystal, are attacked to a lesser extent in a thin layer of material on the side wall juxtaposed just above the cone 15 to 50. The combustion gases practice as it turned out the surface 27 of the melt 19 is applied. There is one on the raw materials leaving the pipe 38 by proceeding in this known manner, expanding effect, so that the raw materials After they have melted, the raw materials are immediately placed in a ring-shaped zone on the Obertelbar Discharged to the mentioned cone, so that the surface of the melt settles. If at the product table no products of wear and tear on the refractory side with this furnace raw materials with another If the walls are to be processed for the outflow opening in the furnace bottom, the In this process, it has been found that the size of the annular zone is also, as it were practically avoided that gas inclusions in the pointed, by adjusting the tube 38 in the Melt occur. Maintain height direction. If the grain size According to the invention, the mean path, which is selected from 60, for example, smaller, the distance A between the melted raw materials to the outflow opening see the tube and the melt surface 27 is laid back in the ground, enlarged, when reduced, the raw materials in a substantially ring-shaped claims zone applied to the melt pool surface. This zone, indicated by 31 in Figure 2, is located at 65 1. Processes for melting glass, e.g. their outer circumference at a distance from the inner wall of quartz glass, using a furnace with 29, and with its inner circumference it completely surrounds one of the outflows located in its bottom part * in Fig. 1 with 33 designated part, which is just opening for the melt and burner flames, which are directed approximately horizontally over the surface of the molten bath, with the raw materials for the melt applied in a thin layer to the melt and fused with it are, characterized in that the raw materials on the molten bath surface in a substantially annular zone (31) are applied, the part located above the discharge opening (drawing cone 15) (33) leaves the molten bath surface completely free and its outer boundary at a distance of the furnace inner wall (29) lies. 2. The method according to claim 1, characterized in that the combustion gases are unidirectional upwards about a center line running through the discharge opening in the vertical direction swirl to a gas outlet opening provided at the top of the furnace and pass through this outlet opening through fed raw materials over at least part of the up to the melt surface distance to be covered during the fall under the influence of the swirling Gases are advised to fall onto an annular zone on the surface of the melt. Considered publications:
German Patent No. 622,234;
U.S. Patent No. 2,958,161. 1 sheet of drawings 609 587/92 6.66 © Bundesdruckerei Berlin