DE1596437A1 - Manufacture of flat glass - Google Patents

Description

DR.ANTON KÜHLER l ^ Zlll . " _T

PATENT ADVOCATE

i-1836 German K / B.

Ford-Werke AO ₀ , Cologne-Deuts Manufacture of flat glass

The invention relates to a method * ur production of ron Flat glass according to the so-called "FlieBveTfahren", whereby a Glass strip is formed on the surface of a molten metal bath so that there is a true parallelism of the opposite surfaces and a shiny fire-polished surface appearance is obtained *

The Schraelsbad is contained in a chamber in which one regulated protective atmosphere is maintained above the bath. After the formation, the glass ribbon is over the The surface of the bath is moved and gradually cooled, so that the tape hardens enough for it to be at the end of the Bades on more or less common orphans without a problem its surface can be removed. The tape will then passed through a TemperungskUhlofen and continue processed in the usual W «io <*.

At the temperatures at which the bath is operated (up to about 9QO ⁰ C) , the metals in question are subject to rapid oxidation of the upper parts exposed to the atmosphere.

1098U / 0297 bad or, g, _N al

area. The formation of a surface oxide usually has a detrimental effect on the underside of the glass ribbon and as a result a non-oxidizing school atmosphere is applied over the molten metal bath to prevent this oxidation and to keep the formation of defects on the surface of the glass to a minimum. The clean atmosphere contains a non-oxidizing gas, usually nitrogen, which is not chemically linked to any substantial extent with the molten metal of the Bades reacts. A small portion of the gas can consist of a reducing agent, for example a mixture of hydrogen and carbon monoxide, which may be in the atmosphere reacts due to the oxygen present in the chamber and prevents oxidation of the surface of the molten metal «

Usually a bath is used, which is at least The main thing is that it consists of tin. "Molten tin at high temperatures oxidizes rapidly in the presence of even small amounts of oxygen, and it was" inherent that the an The presence of even a small amount of tin oxide on the surface of the bath causes a change of tin in the glass, because of the disruptive effects on further processing caused rainbow-colored blooms on the surface of the glass that was exposed to the tin.

1098U / 0297 <· »« iq-nai

Furthermore, there is a tendency for particles to drip onto the glass ribbon before it hardens and give rise to defects are usually denoted as "top spots" or "drops". These surface defects appear from the dripping originate from substances on radiators, on the underside of the chamber roof and on other building components to stir above the tape, and possibly the Drips embedded in or deformed the upper surface of the tape. Such connections are likely sulfides and oxides that were formed inside the chamber. The reducing kind of atmosphere can also contribute to this problem by causing tin oxides and sulfides to become molten on components above the Bantfa Tin are reduced, which in turn drips onto the tape and firmly bonded to the surface of the same is · It is believed that the sulfur is introduced into the chamber along with the glass from the furnace and that the oxygen into the chamber from the outside atmosphere or possibly as a result of a small amount of decomposition some of the oxide components of the glass seep in. Also, a certain amount of tin becomes at the operating temperatures the chamber evaporates and can condense on surfaces above the belt «

Attempts have been made to remove the top spots or To reduce drops “by the protective atmosphere only very was kept low reducing. This results in each

1098U / 0297 bad original

but a tendency to form a large amount of tin oxide on the surface of the bath. Day material can also pass through Stop working and blow out with nitrogen from can be removed at high pressure without reducing the temperature inside the chamber. However, this interrupts the production and still does not completely eliminate these errors avoided ρ

According to the present invention, the protective atmosphere becomes returned inside the chamber through a cleaning system to remove metal vapors, for example from tin, and tin and to remove sulfur compounds that reduce the deposition of substances which may later drip onto the surface of the belt.

In the inventive approach, the atmosphere is recycled and washed, and chemically treated _t after which the atmosphere is returned to the chamber so that COo, oxygen "metal vapors and the like are removed. This reduces the oxidation of the metal _v , for example tin, and prevents condensation of metal vapors, eg »tin vapors on parts of the deodorant part of the chamber and their dripping onto the upper side of the tape with the formation of surface stains.

Dae method according to the invention for the production of flat glass according to the flow process consists in that a continuous

109814/0297 ^{ßAD or} 'G'Nal

light band ron glass poured onto a bath of a molten metal inside a closed chamber becomes a non-oxidizing atmosphere within the chamber above the glass and the molten metal is maintained and at least a part of the atmosphere inside the chamber is awakened by a washing and cleaning system Removal of contaminants from the atmosphere is recycled. Particularly advantageous lot a method according to the invention for the production of flat glass naoh the Flow process whereby a continuous ribbon of glass is closed on a bath of molten tin within a A reducing atmosphere within the Kemmer above dos glass and the molten chamber is flowed up Zinna is maintained and at least part of the atmosphere inside the chamber is maintained by an electrical system Removal of contaminants from the atmosphere is recycled.

The inventive device for producing ron flat glass consists of a closed chamber, a bath of molten "metal within the Kamaer, means for forming a continuous Bandeβ-by on the molten metal flowing glass and for continuously withdrawing dme tape from the chamber, means for Aufrechterhultung a non-oxidizing atmosphere within the chamber close to the bonds and the molten metal, in order to remove oxide and sulphide

1 0 9 D U / 0 2 9 7 bad original

purifications from the atmosphere and facilities for cleaning the atmosphere from the chamber through this device and for the return of the cleaned atmosphere into the chamber,

In a beTorsugten embodiment of the invention, the The atmosphere is continuously removed from the zones with a higher temperature of the chamber and passed through a filtering and cleaning system, which consists of activated carbon filters, washers, Compressors, catalyst chambers and dryers can exist in any combination before it is returned to the chamber. Bas filtration and purification system is located separated from the chamber so that the removal of the contaminants can be carried out as a continuous process without affecting the manufacture of the flow glass ribbon.

Objects of the present invention include retarding the formation of surface imperfections on after Hot-process manufactured glass, maintaining a non-contaminated protective atmosphere in the chamber Above the molten metal, facilities for cleaning up and purifying the atmosphere used in the chamber of plied glass treatment equipment and in general improved equipment and procedures for Horn division of glass according to the flow process.

BATH ORIGINAL

109814/0297

Other objects and advantages will emerge according to the invention

calibrate from the following description in conjunction with the drawings, in which

Pig. 1 is a vertical section schematisehen a chamber for the production of float glass, with which the teaching of the invention can be applied, a portion dee released end of the glass melting and refining furnace and part dee TemperungskUhlofens,

Pig. FIG. 2 is a schematic view in the plane of FIG shown chamber and the adjoining parts,

3 is a schematic side view of the chamber and the parts connected therewith and

4 shows a schematic representation of a system for cleaning and filtering the protective atmosphere before it Return to the chamber

demonstrate"

In the production of glass by the flow process, a glass, which usually has a more or less usual composition, for example soda-lime glass, is made in a common type of smelting and refining furnace, and on the surface of a bath of molten metal, preferably molten tin, optionally together with Alloying elements, abandoned «The glass spreads underneath Formation of a layer of uniform thickness that floats on the surface of the tin, and as the tin cools down Glass and by cooling the glass and removing the tape

SAD ORIGINAL

1098U / 0297

At a steady rate, a band of uniform width and thickness is formed. The chamber becomes progressively cooler in the direction of the exit, so that the Belt is sufficiently cooled »so that ee at the exit end of the Chamber can be removed by more or less common orphans without damaging the surface of the glass will. The glass obtained thereby has an excellent fire-polished surface appearance and is of good visual appearance Quality.

In the drawings, Figure 1 represents one more or less usual glass furnace 11, in which the glass 12 is melted and is refined. A constant height of the molten glass 12 is maintained inside the furnace and from here the glass comes through a forehearth 13 into a closed one Chamber 14 ° Sine orifice 15 can be used to regulate the flow rate of the glass from the furnace. the Chamber 14 is set up in such a way that it has a bath 16 from molten metal contains tin, whereupon the glass under Formation of a continuous belt 17 flows

The tin bath 16 is held in the bottom part of the chamber 14 by refractory blocks 18. The chamber 14 is made up of side walls 19 «end walls 21 and 22, which are provided with exit or entry openings, and a roof part 23, which from the surface of the tin bath a 16 is spaced to give a head space or plenum 24, formed * The floor

1098U / 0297 bad or.g.nal

part of the Kaaeer 14 can be requested with one Carbon-formed lining 25 be provided

The chamber 14 is largely melted by the de « Glass, which is introduced into the chamber with a temperature tone about 1010T, heated heat supplied, A number of electric heaters 26 and coolers 27 are carried by the roof part to add or remove heat therewith the necessary drop in heat is obtained so that initially the glass is of uniform thickness across the width of the Tape flows and later the tape is sufficient (to about 590%) is cooled so that it can be removed without damaging the surface of the glass. A local cooling off can also be used to keep the band at a value less than the equilibrium value of the strength to which it tends to return under the influence of gravity and surface tension, and to raise the temperature across the width of the The band to the same value. »

In the room 24 a protective atmosphere is used to protect the molten metal, SB, tin, against oxidation. The atmosphere is introduced into the chamber via the Elnläße 28 in the roof portion 23 is preferably preheated to about 54O ⁰ C and is additionally urhitzt by the heater 26 within the chamber. A small volume of the atmosphere is continuously added to the chamber in order to compensate for losses at the outlet opening of the belt 17 and other losses.

1098 U / 0297 bad original

~ ίο -

The protective atmosphere, which is reducing, consists of an inert gas, preferably nitrogen or argon, at about 83 to 90 ° and a reducing gas which can react with any oxygen present in the atmosphere above the bath . The reducing gas preferably consists of hydrogen monoxide with a small amount of carbon. The reducing gas reacts preferentially with any oxygen present and consequently prevents the oxidation of the metal, especially tin, and the formation of a film of tin oxide on the surface of the glass, which would damage the quality of the glass.

The glass ribbon 17 goes through the chamber 14 and through an exit opening in the end wall 22 of the chamber. The outlet opening is fitted with a seal and the atmosphere Inside the chamber is maintained above atmospheric pressure around the entrance of those outside the chamber To complicate the atmosphere »Immediately after leaving the chamber 14, the belt 17 enters a tempering cooling furnace 29, in which it continues to cool under controlled conditions to remove residual stresses, and the cutting and the next ·? To facilitate processing of the glass. A number of rollers 31 aind in dom cooling furnace 29 attached to support and structure the band

1008U / 0297

1596A37

3) SchutsatBOiphiire within Kuawr 14 significantly reduces the defects in the glass due to the presence of tin oxide The upper surface of the band 8 has defects which are usually referred to as all ⁿ top-side ^{spots x 1} or "drops". These faults appear to be due to the dripping of metallic tin and tin sulfide and oxide into the atmosphere, which form in the atmosphere or are absorbed by it, and which are deposited on the water coolers 27, the heaters 26 and other exposed structural components of the roof 23 of the chamber condense. It is also evident that the atmosphere sometimes reduces these compounds and strips them off so that they fall on the upper surface of the belt 17. Also, by cooling or regulating the coolers or other components, a loss of the accumulated matter can occur enter so that they drip onto the tape.

Ee it has been found that top fleoks or tops * drips can actually be completely avoided if the atmosphere is removed from the Kanaer U by a covering systea 32 and then the gas is heated again and su the Kaajmer is returned. This prevents the accumulation of oxygen and sulfur compounds in the atmosphere and the removal of any tin fumes

BATH ORIGINAL

109814/0297

As on beaten from the Flg. 2 and 3, the stale atmosphere is preferably removed from the hotter zones of the chamber 14 by a series of pipes 33, for example approximately 7.5 cm, which are attached to each side of the chamber ο Preferably the pipes unite in the side walls of the chamber, for example about 45 cm above the surface of the molten bath, control valves 35 are provided in each line so that regulation of the exhaust of the used atmosphere is allowed up to about 760 ⁰ C,

The atmosphere, after being treated by the gas cleaning system 32, is returned to the chamber through a return line 36, preferably in a number of of branches 37 which enter the roof section 23 in the hotter zones of the chamber. Preferably the inlets are for the recirculated atmosphere offset into the chamber in the longitudinal direction of the chamber opposite the outlets, as shown in FIG. 2. The valves 39 are used to regulate the flow through the branches 37 ″. If desired, a flow meter 38 can be inserted in each branch.

1098U / 0297 ^BAD

Ee proved to be particularly advantageous if the polluted atmosphere is sucked off from the two bays of the chamber adjacent to the inlet where the temperature is the hottest (about 1010%) and the renewed atmosphere is returned to those bays where the temperature in the area is wiped out is about 870 and 76O ¹ C; this zone has seems a short distance from the heißesten zone at the end of the chamber .. Ea a great tendency but Auebildung of surface stains and drops in the heißesten zones of the chamber do exist, because the condensation above the belt in these surfaces takes place to a greater extent, In addition, belt 17 is softer and more susceptible to damage in this area. It should be noted, however, that the invention in its broad scope is not limited to circulating the atmosphere within the hotter zone of the chamber, and that the atmosphere can be drawn off or renewed from other zones if so desired. In the following, an analysis in which the possible impurities in the atmosphere of a typical flow glass facility are found is indicated in column A, and the desired amount of impurities in the atmosphere is indicated in column B.

BAD ORIGINAL 1098U / 0297

-H-

A.
Respondents mVstd, (15000 SCPH) B.
product Nitrogen, N ₂ 90 # 90 * Wassere toff, ed 5 * 5 * Carbon monoxide , CO 5 * 5 * Dew point, H ₂ O - 23 ¹ C (-10 ⁰ P) - 51 ¹ C (-60 ° P) Oxygen, O ₂ 1 PPM 1 PPM Carbon dioxide _T CO ₂ 100 PPM 100 PPM H ₂ S + SO ₂ + COS 300 PPM 1 PPM Free sulfur 30 PPM 1 PPM SnO, SnO ₂ 50 PPM 1 PPM SnS 150 PPM 1 PPM Temperature* 538 ⁰ C (1000 ° P) 38 ^ (100 ° P) O pressure, 25-1,7cm (O, 1 - O, 5 ") H ₂ O 0.07-0.7kg / cm ² Flow 425 402 mVstd _e (14

A preferred ÄuefUhrungaform of cleaning systems 32 is schematiflob In Pig 4 _n shown.

The contaminated atmosphere withdrawn through lines 33 is obtained at about 538 ^ and 1 "7 cm of water and taken up in a conventional water heater 41, in which the atmosphere is ^{cooled to about 26 11} C to remove SnO ₂ , SnS and other vapor impurities to condense. The atmosphere then passes through a water separator 42 to remove any liquid from the gas inlet and is led to a pressure chamber 43 which never serves as a pressure vessel for a compressor 44, the pressure chamber 43 also serves as an additional separator and contains a filter. The compressor 44 serves to cool down the "Irr Atmosphilr * *" from the barely 4 and to return

1090U / 0297

SAD ORIGiNAL

~ 15 of the purified gas to the room 24 *

After compression, the atmosphere is passed through a water cooler 45 to ^{cool the gas again to about 26 °} C., whereupon it is passed through a second water separator 46 and an activated carbon filter 47, which is used for chemical absorption of any sulfur not removed by the water washing devices The atmosphere then flows through drying towers 48 which remove moisture from the gas by an activated alumina desiccant, preferably lowering the dew point of the gas to about -56 "A mechanical filter 49 then removes any small particles of the fourth aluminum oxides, which may have been taken up from the drying ^{towers 48. The dried gas can be heated to about 290 0} H in a heater 51 for activation and then / a catalyst chamber 52 to reduce the oxygen content of the gas to about 1 PPM are managed. The purified Gae is then cooled through a cooler 53 to about 26 ⁰ C and passed to the HUckführleitung 36 through which the cleaned atmosphere of the chamber is returned to 14 where ale l> eim erhitzt'wird entry into the space 24th

It is apparent from the above description that practically all impurities that accumulate in the atmosphere by circulating the gases »through the scrubbing and cleaning devices are removed, so that the atmosphere

1098U / 0297

BATH ORIGINAL

Room 24 is free of oxide and suI fid contamination, and therefore the formation of condensates in the chamber avoided which surface damage on the upper surface of the glass ribbon 17 can cause. When the atmosphere is removed from the hottest part of the chamber H and renewed in an adjacent part of the chamber those usually present in vapor form in the atmosphere Impurities removed and not built up within the chamber where they adversely affect the quality of the glass.

109814/0297

Claims (1)

- 17 P a TENT CLAIMS 1. A process for the production of flat glass according to the flow process, characterized in that a continuous bundle of glass is flown onto a bath οίηβε molten metal within a closed chamber, 9 a non-oxidizing atmosphere is maintained in the chamber above the glass and the molten metal and a part of the atmosphere within the chamber ./arjch- by -sin Reinißungßeyötera and is led to the removal of contaminants from the atmosphere in the circuit, 2-. The method of claim 1, characterized in that _v is a Bad _t which consists at least mainly of molten tin, used " 5. The method according to claim 1 or 2, characterized. that dan band in the area of an end portion of the chamber is gebildot at a temperature of about 98 (FC and the ^L: in / of the chamber jfi cooled and Del a temperature of about ^ 90 ⁰ C emerges from the other end portion of the chamber, and the atmosphere to be healed and cleaned in the zones of the chamber in the area of its hotter end part withdrawn and winder eln /; f. leads v / J rü. & AD ORIGINAL 1098U / 0297 4. The method according to claim 3 »characterized in that the Chamber is provided with side walls and a roof section and the atmosphere is removed from the chamber through the side walls and is returned to the top of the chamber through the roof section » 5 ο method of claim 4, "characterized in that the atmosphere removed from the heißesten part of the chamber and in an adjacent zone of the chamber, .the at a temperature lower by at least 100 ^ is operated as the pick-up zone is introduced. 6ο method according to claim 1 to 5, characterized in that that a bath of molten tin is used and a reducing atmosphere within the chamber above Glass and molten tin is maintained- 7. The method according to claim 6, characterized in that the reducing atmosphere mainly made up of nitrogen and a smaller part of a reducing gas, carbon monoxide and / or contains hydrogen "consists and by the Purification system the contaminants picked up by the atmosphere inside the chamber, including Zi in and its oxydo and üuLl'Lde, are removed., 1098U / 0297 8. The method according to Anapruch 7, characterized in that the tape is formed in the area of a Sndteiles of the lamers at a temperature of about 960 ⁰ C and cooled over the length of the chamber and from the other end of the Kaamer at a temperature of about 590 "O step out, and the eu washing and su purifying Ataoaphäre In the zones of the Kaismer in the area of whose hotter end part is withdrawn and reintroduced. 9. The method according to claim 1 to 8, characterized in that the cleaning aayatea also removes moisture by lowering the dew point of the ataoaphare below a value of -18 ⁰ C before the. .noaphäre eur chamber is returned. 10, device for the production of flat glass, consisting of a closed chamber (14), a bath (16) of molten metal within the chamber (14), devices ( _{12, 15 B} 29, 31) for forming a continuous strip (17) of glass flowing on the molten metal and for continuously withdrawing the tape (17) from the chamber (U), means (28) for maintaining a non-oxidizing atmosphere within the chamber (14) above the tape (17) and dee molten metal, a device (41 to 52) for removing oxide and sulfide impurities from the atmosphere and devices (44,54) for guiding the atmosphere out of the chamber through the BATH ORIGINAL 1038U / 0297 Direction and return (36) of the cleaned atmosphere into the quay (H). 11. The device according to claim 10, characterized in that the means for guiding the atmosphere (33 to 39) · withdraw the atmosphere from the hotter zone of the chamber (14) and return it to this hotter zone «. 12. Apparatus according to claim 10, characterized in that the device for removing the impurities a waaserwasher (41), a filter (49) and a dryer (48) contain BATH ORIGINAL 1Ö98U / 029? Blank page