FI89582B - Glass melting furnace - Google Patents

Description

1 89582

Glass melting furnace. - Glassmältugn.

The present invention relates to a glass melting furnace in which a mixture is melted in a melting section, clarified in a clarifying section associated with the melting section, then homogenized in an associated elevated bath homogenization section and withdrawn therefrom. with burners arranged in the clarifier to supply energy.

Glass melting furnaces generally, although operating on recuperators or regenerators, have a relatively low efficiency. This is not due to the inadequate insulation of the glass tubs, but to the fact that the heat of the exhaust gas is considerably higher than the thermal energy required for preheating the combustion air. Limits are then set for raising the temperature of the combustion air, because as a result the heat exchange becomes very input, however, especially the concentration of toxic NOx increases sharply.

Various attempts have already been made to make meaningful use of the excess heat in the exhaust gas, including preheating the mixture before adding it to the las Insula shower. However, these attempts have been unsuccessful, as preheating of some alloy components may already occur due to heating, as a result of which the heat exchange surfaces stick together and, on the other hand, in addition to pre-melting of certain components, decomposition also occurs. if the dust content of the exhaust gas is increased unauthorized or, if necessary, well-charged dust filters are required.

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The object of the invention is to provide a glass melting furnace in which a mixture with a large proportion of fragments and the rest of a conventional mixture can be used. To achieve this object, the furnace according to the invention is characterized by the things set forth in the characterizing part of claim 1.

The furnace according to the invention is economically manufacturable and safe to use, whereby extensive exchange of fossil and electrical energy is possible if necessary.

Clearly, the glass melting furnace according to the invention is able to solve the problems encountered in a very advantageous manner and uniquely.

In the following, embodiments of the invention will be explained in more detail with reference to the drawings. In the drawings, Fig. 1 shows a longitudinal sectional view of a glass melting furnace according to the invention, Fig. 2 shows a longitudinal sectional view of an actual melting bath according to another embodiment of the invention, Fig. 3 shows a top view of the tub at the height of the surface of the glass bath, and Fig. 6 shows a sectional view of the bath according to Figs. 4 and 5 above the surface of the glass bath.

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In detail, the bath is formed according to the conventional technique described in the applicant's previous applications, so that it does not need to be explained in more detail. This applies in particular to the discharge 19 at the distal end of the mixture of walls, vault, base, burners, electrodes and the homogenization part 2a and the structure of the exhaust gas outlets 22 right next to the mixture supply.

The glass melting furnace according to the invention can be manufactured economically because, due to the lower temperatures, a cheap refractory material can be used in the charging part of the mixture.

For the use of the furnace according to the invention, it is essential to work with a mixture with a large proportion of fragments and the rest with a conventional mixture, so that it is possible to use the furnace with cheap base materials. Due to the ever-increasing amounts of recycled waste glass, which cannot currently be separated according to color, shards with different oxidation potentials enter the melting bath. In the reaction of glasses with different oxidation potentials, a strong foam is formed on the surface of the bath, which reflects the flame radiation and strongly prevents the flow of heat to the glass bath.

This foam can be reduced by strongly reducing combustion control, so that the new tub operates under unfavorable conditions when using large amounts of waste glass more advantageously than conventional tubs.

This relative independence from the quality of the raw materials is realized by the equipment according to Figures 1-6. Here, the clarification and thus the quality of the glass can be determined completely independently of the melting part, since no return flows occur. Also, the use of inhomogeneous raw materials and strong foaming or the use of sodium hydroxide, which contains a lot of volatile water, has no effect on the quality of the glass, whereby homogenization takes place in the melting section with bubbling devices.

The savings obtained by using cheaper raw materials then largely outweigh the costs required for higher energy requirements for foam formation.

The following description is limited to the different structure of the furnace according to the invention compared to the prior art, which is sufficiently known.

According to Figs. The highest temperature of the glass stream is then very low in the area 34 of the clarifying part 2, whereby corresponding heating can take place with both burners 20 and electrodes 36. However, it is particularly advantageous to conduct relatively lower energy relative to electrical energy with burners, whereby a complete bath temperature is guaranteed.

The uniformly heated glass thus arrives from the region 34 to the homogenization section 2a, where it sinks like a "piston flow" without swirling in cooling. Cooling then ensures that the existing layer of glass is not left, so that vortexing certainly does not occur.

The mixture is charged at the front (from a flow point of view) end of the melting section 3, whereby it is conveyed in the direction of the clarification section 2. However, transport to the clarification section is prevented by an arc 38 with a bottom opening 37, whereby the arc 38 can be cooled with air. This air, which is later used as combustion air, can be directed in pipes made of, for example, Inconel, which is resistant to intense heat.

After the bottom opening 37, the glass, which is no longer mixed with the mixture, rises in the piston flow, because the energy supply from above also here adjusts the desired deposition so that the coldest glass occurs at the bottom and the hottest glass at the top. Thanks to this temperature deposition, a "piston flow" is formed here without swirling. This ensures that the already preheated glass does not enter the actual clarification zone or that the glass already heated to a high temperature sinks again into the front of the clarification part 2.

In order to ensure a very strong energy supply, roof burners 24 can be arranged at the rear end of the melting part 1, whereby under each ceiling burner there is an air blowing device 25, which ensures that the colder glass is constantly flowing more and thus overheating is avoided. A corresponding air blowing device 25 can also be located below or in the corresponding area of the mixture supply point, so that a glass flow is continuously produced here and solidification is prevented.

According to Figure 1, the still fed mixture or the newly fed fragments can also be preheated. The flue gases are withdrawn from the clarification and smelting sections 2 and 3 in the mixture feed zone and directed countercurrently past both the mixture and the fragments before being discharged into the environment through the cyclone 27 purified. The solids then return from the cyclone 27 to the mixture tank 31, from where they are removed or fall out against the flue gas stream. In the fragment control channel 2Θ, a flue gas flow flows through the controlled fragments, whereby the fragment control channel 28 consists of individual surfaces (dampers) 29 which are spaced apart and inclined obliquely inwards, so that the flue gas flow can enter the fragments thus formed.

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In order to obtain glass of a special quality, according to Figure 1, the bottom of the homogenization part 2a may be substantially below the level of the bottom of the melting part. The supply of the mixture and the fragments, on the other hand, and the removal of the combustion gases can then take place via the openings 22.

Figures 2 and 3 show a simplified form of an oven according to the invention, in which heating takes place in the melting part 3 via electrodes 6. The mixture then extends to a considerable part of the melting part 3. The molten glass then flows, as in the furnace of Figure 1, through the bottom opening 37 into the clarifying part 2 and is then heated during the rise by the second electrodes 6 and from the surface by one or more burners 20. Here too there is a "piston flow" during the rise , where there is a smaller depth of the glass bath already shown above.

The glass then flows in a second piston flow according to the flow, viewed at the rear of the clarification part 2, to the second bottom opening 30 and from there to the homogenization part 2a, where the losses or the desired temperature layer adjustment by burners 20 can be compensated.

The arches 38 and the bottom of the clarifying part 2 can likewise be cooled by cool combustion air directed in pipes consisting of a high-temperature-resistant material.

According to Figures 4-6, the melting of the mixture in the melting section 3 is carried out by supplying electrical energy through the electrodes 6, and the clarification section 2 flows first upwards and then downwards, as shown in connection with Figures 2 and 3. However, the indirectly heated working bath with burners 20 and indirect heating 26 now preferably acts as the homogenizing part 2a.

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In order to prevent backflow, certainly without removing the glass from the homogenizing part or so, a flow reducing section 41 of refractory material is arranged in the clarifying part 2, which divides the flowing glass flow into two parts and also does not allow horizontal swirling. Because of the energy supplied through the burners 20, the desired temperature layer is maintained in the clarification section without vortexing even during downtimes, the structure is very well suited for furnaces with intermittent intake. Indirect heating then also ensures that the desired temperature deposition is maintained in the homogenization section 2a or equivalent, even in the working bath, without intake. Thus, the temperatures here would also have been adjusted in the desired way without flow-through.

Thus, an essential part of the invention is that in the clarification part the defined temperature deposition is adjusted by avoiding any kind of turbulence, whereby this is also achieved during heating or resistance, during cooling and in the range of the highest temperatures due to the small bath depth.

Claims (6)

8 8 9 5 S 2 A glass melting furnace having a melting section (3), a homogenizing section (2a), and an intervening clarification section (2) having a smaller bath depth relative to adjacent sections, the clarifying section having burners (20) for supplying fossil energy and / or electrodes ( 36) for supplying electrical energy, and the mixture charging section has electrodes (6) for supplying electrical energy to the mixture charging area, a first bottom opening (37) being arranged between the melting section (3) and the clarifying section (2), characterized by a low area ( 34), in which additional energy is supplied by said burners (20) and / or electrodes and in which area the highest temperature of the whole furnace is present; that a second bottom opening (30) is arranged between the clarification and homogenization sections (2 and 2a); and that the glass flows into the shallow region (34) and further from there to the homogenization section as a piston flow, i.e. without vortexing. Glass melting furnace according to Claim 1, characterized in that pipes (39) are arranged in the refractory material of the arc (38) of the discharge opening (37) for the passage of cooling combustion air. Glass melting furnace according to Claim 1 or 2, characterized in that the tubes (39) are also arranged between the clarification and homogenization section (2 and 2a) of the arc of the discharge opening (30). Glass melting furnace according to one of Claims 1 to 3, characterized in that the homogenizing part (2a) is formed as a working bath. Glass melting furnace according to one of Claims 1 to 4, characterized in that the clarification section (2) has a flow reduction section (41) in the low region (4). 9 89582 Glass melting furnace according to one of Claims 1 to 5, characterized in that roof burners (24) and an air blowing device (15) are arranged below each burner in accordance with the flow of the melting section (1). 10 89582