CZ304703B6 - Glass melting furnace for continuous melting of glass by controlled convection of molten glass - Google Patents

Abstract

In the present invention, there is described a glass melting furnace, wherein power sources are arranged in the melting space in at least one row in the melting space longitudinal axis, or parallel to said longitudinal axis, and namely between a gable wall (2) and a transverse damming (7) in the molten glass (6) optionally with a transverse row of power sources (9) in the molten glass (6) melting section for generating a helical flow of the molten glass (6) with circular motion across the melting section. The power sources can be arranged in one or both lateral walls (4). The power sources are arranged at regular spacing. The power sources are represented by heating electrodes (10) and/or industrial glass burners (11). The melting section is preferably terminated by a transverse row (9) of heating electrodes (10) that are installed in the bottom (1).

Description

(57)

A glass melting furnace is described wherein energy sources are arranged in the melting chamber in at least one row along or parallel to the longitudinal axis of the melting chamber, between the loading wall (2) and the transverse dam wall (7) in the glass (6). or a transverse row (9) of energy sources in the glass melting portion (6) to induce a spiral flow of glass (6) with a circular motion across the melting portion. The power sources may be arranged in one or both side walls (4). The energy sources are arranged at regular intervals. The power sources are heating electrodes (10) and / or industrial glass burners (11). The melting portion is preferably terminated by a transverse row (9) of heating electrodes (10) installed in the bottom (1).

Glass melting furnace for continuous glass melting by controlled glass convection

Technical field

BACKGROUND OF THE INVENTION The present invention relates to a glass melting furnace for the continuous melting of glass by controlled glass convection, in which molten glass containing insoluble particles, in particular glass sand, is disposed in a horizontally oriented and separate through-flow melting space by energy sources acting on the glass in the melting furnace. space. The melting chamber comprises a bottom, a base wall and a rear flow wall, and opposed side walls, a vault, and a transverse dam wall immersed in glass.

BACKGROUND OF THE INVENTION

Continuous melting of glass is a method of preparing traditional material on a mass scale by melting directly associated with the processing of the resulting raw material in many ways. Its foundations date back to the 19th century, when the emerging glass technology was inspired by another melting process, the production of steel. In accordance with this process, the first continuous glass equipment called glass pans was created as covered horizontal spaces lined with refractory materials, into which a glass batch was placed at the inlet, most often a mixture of crystalline raw materials with variable proportion of glass cullet. melt. The devices were heated by means of burners placed above the surface of the melt with the heating medium gas or oil. It was therefore a compact, top-fired single-space device, which was later divided by flow or constriction into the melting section where the glass-homogenization processes were carried out and completed, and into the working section where the melt was primarily heat-homogenized for processing. The melt flow through these devices was essentially horizontal, but due to naturally occurring temperature differences by feeding the cold charge to the melt level, the type and location of the heating and the different levels of heat loss through the interface, the natural circulation flow always stabilized in the melting and working space. with flow flow created a relatively complicated flow pattern in the furnace space.

Later, other types of glass melting chambers have been developed, mainly heated electrically, and characterized by a substantially vertical melt flow through the melting chamber and with a similar composite melt flow. However, spaces with predominantly vertical flow are not covered by this application.

The problem of melting unusable circulating melt volumes allowed to specify the tests of the so-called transition characteristics of melting spaces [1-3]. In these tests an indicator was introduced at the melter inlet, its indicator character did not change during the melting process and identifiable at the outlet . The most common indicator was suitable radioactive isotopes. Monitoring the character of the indicator in the resulting glass over time provided information on the nature of the flow in the melter. It also helped to identify the space in which the melt only circulated. The measured proportion of such spaces, called dead space ratio, was often 0.5 in conventional melting plants, and in some plants it was even larger. Thus, it was clear that the flow pattern plays an important role for the efficiency of the melting process. A little later, Cooper [4] defined, based on flow type and melting process kinetics, a quantity that is the ratio between the rate constant of the controlling melting process and the mass flow rate that provides the degree of termination of the process at a given location or space trajectory. The thesis emphasizes the importance of flow character for melting processes.

The search for an efficient method of melting glass required a very detailed knowledge of the conditions under which the melting process takes place in industrial space. Such knowledge was only provided by mathematical modeling of the melting process in operated glass tanks. Applications of mathematical models provided detailed temperature and velocity fields of the melt in melting spaces

Thus the melting processes were modeled directly when the mixture flows through a specific melting chamber [5-24]. The results confirmed the conclusions obtained by previous experience and measurements. A relatively complicated type of flow consisting of combinations of longitudinally and transversely rotating regions and a flow was established in the melting rooms, which was strongly influenced by the melt circulation. The dissolution process took place under relatively unfavorable temperature conditions [20], the fining process was essentially limited to a small region of the melt temperature maximum [19-24], and the melting compartments indicated a high dead space proportion [12]. critical paths, i.e., melt paths through the melting space, at which the respective homogenization process in time closest to the exit of the space is completed. Often there were short-circuit paths passing through a space with low residence times, moreover, under not very favorable temperature conditions, which considerably limited the melting performance of the space and increased the specific energy consumption for the melting process. Efforts have been made to eliminate such short-circuit path by influencing the flow [25]. The complex natural flow in the melting aggregates was very difficult to influence in the right direction, since the optimum flow pattern in the melting compartments was not investigated in detail. However, Cooper [26] has previously described some of the consequences of a given type of flow for homogenizing the melt (eg accelerating process homogenization and transverse flow temperatures) based on a simple mathematical model of glass melt flow in a simple model space. These results indicate the need to influence the flow in the melting chamber based on a detailed knowledge of the relationship between the individual types of flow and their effect on the respective homogenization process. Recent global challenges to energy, material and environmentally less demanding technologies - including glass technology - have triggered further activities involving both changes in the necessary melt residence times in the melting space and changes in the overall layout of the melting process [27]. However, the need for such changes requires the application of new principles to the melting process, including changes in the spatial arrangement of the process, eg in the form of so-called segmental melters in which the sub-processes take place separately, alternative heating characteristics, etc. it requires a partial distance from commonly modeled existing industrial facilities to simple model spaces operating under precisely defined conditions under which the principles can be sufficiently understood, to find their general patterns for later safe application. Such a process also includes efforts to overcome the disadvantages of naturally established flow in glass melting furnaces.

SUMMARY OF THE INVENTION

These disadvantages are avoided or substantially reduced in a glass melting furnace for continuous glass melting by controlled glass convection in the melting chamber of the present invention. The invention is based on the fact that in the melting chamber, the energy sources are arranged in at least one row along the longitudinal axis of the melting chamber, or parallel to the longitudinal axis of the melting chamber, between the loading wall and the transverse dam wall in the glass. glass melting portions for inducing a spiral flow of glass with a circular motion across the melting portion.

The main advantage of the invention is that the melting part, by its arrangement of energy sources, allows to generate a spiral flow, which significantly reduces dead spaces in the melting space where the process does not take place and where the glass is unnecessarily consuming energy. Thus, a uniform temperature distribution in the molten glass is created in the melting chamber. The flow of the glass has an excellent homogenizing function and thus the process of dissolving hard-melting particles, especially glass sand or corundum particles, is shortened. The defined arrangement of the energy sources ensures effective achievement of the desired spiral glass flow. The melting chamber exhibits lower heat losses and a high melting capacity, which allows a possible reduction of the melting part and, as a result, construction savings.

Preferably, the power sources are arranged in one or both side walls of the melting chamber. When the energy sources are arranged in one side wall of the melting portion, one helical flow occurs across the entire melting portion, which is suitable for narrow melting portions. If there are sources

If the energy is disposed in the two side walls, two substantially symmetrical spiral flows are formed separated by the longitudinal axis of the melting portion, which is suitable for melting areas with difficult operator access to the bottom in case of displacement or replacement of heating electrodes. In larger glass furnaces, ie with a larger melting space and width, it is possible to use bottom heating electrodes in two or more rows in the longitudinal direction of the melting space. In this case, spiral flows occur between each side wall and the row of heating electrodes and between the individual row of electrodes.

It is also preferred that the energy sources are arranged at regular intervals from each other. Regular spacing ensures uniform heating of the melt and thus a favorable even flow of glass.

Energy sources are heating electrodes and / or industrial glass burners. The heating electrodes are the most advantageous for the spiral flow because of the direct supply of energy to the glass and the easy regulation of the heating electrodes. The heating electrodes may be arranged in the bottom as vertical or inclined, or they may act on the glass from above as vertical. Plate electrodes installed in the side walls seem to be suitable. There may be other sources of heating energy, for example microwaves or plasma torches.

It is also preferred that the melting portion terminates in a transverse row of bottom heating electrodes. This transverse row of heating electrodes creates a transverse thermal barrier, which is an alternative to the transverse dam wall, and moreover allows for better regulation of the heat output depending on the melting capacity of the glass furnace.

In the case of very small melting rooms for special glass, other sources can be used as energy sources, eg microwaves, plasma torches or resistive sources in the side walls, or indirect sources of heating energy in the side walls, super-channel loops.

The main advantage of the present invention is the noticeable reduction of the space in the melting portion, the so-called dead space, i.e. the places where the melting process does not take place or only with very low to zero efficiency and the glass is unproductively heated in these places. An important advantage of the present invention is the possibility of adjusting the ratio of the transverse temperature gradient to the longitudinal temperature gradient, which is created by a suitable arrangement of energy sources, and which creates favorable conditions for spiral glass flow through the melting space. . Thus, there is a significant reduction in heat loss and a substantial increase in the melting capacity of the glass furnace, which eventually allows for a proposal to reduce the melting portion and thereby save costs for the construction of the glass melting furnace.

It is preferred that the ratio of the transverse temperature gradient to the longitudinal temperature gradient be in the range of 1 to 30, which represents the real widest limits. Optimally, this ratio is used in the range of 5 to 20. If this ratio is less than 1, the spiral flow of the glass does not occur. If this ratio were higher, a spiral flow would also be advantageous, but the efficiency of adjusting this ratio does not outweigh the technical difficulties in implementation.

Advantageously, the helical flow of the glass passes through a space whose use for dissolving particles, especially glass sand, amounts to 0.6 to 0.8 of the total space defined by the glass height, the length between the transverse dam wall in the glass or the transverse row of energy sources and the base wall; the width between opposite side walls. The spiral flow of the present invention provides the highest previously known defined utilization of the melting space. The utilization of the melting space represents the amount of used part of the melting space to be unused.

-3GB 304703 B6

BRIEF DESCRIPTION OF THE DRAWINGS

1a and 1b, taken from W. Trier, Advances in Glass Technology, Plenum Press, 1962, p. 619, FIG. 1a shows a longitudinal axial section of a constant temperature glass furnace, without circulation, and FIG. 1b shows a longitudinal axial section through a glass furnace in the presence of temperature gradients and hence circulation.

The invention is described in detail in the following description of the invention, which is generally illustrated in the accompanying schematic drawings, in which FIG. 2 is a perspective view of a simplified basic melting chamber model with full inlet and outlet; Figure 4 is a graph of the maximum utilization of the model melting space, the dissolution time of the glass sand particles, and the length of the model channel of the melting space.

Exemplary embodiments 1 to 4 schematically show in Figures 5 to 24 a vertical longitudinal axial section of a proposed glass pan module with a melting portion of a typical shape and arrangement of heat sources, electrodes, in Figures 5 to 22 of the vertical heating electrodes and Figure 23, 24 combinations of vertical heating electrodes with side wall burners. More specifically, an exemplary embodiment 1 for melting flat glass is shown in Figures 5 to 13, wherein schematically shown in Figure 5 is a melting portion of a typical shape and arrangement of vertical electrodes, with a lower inlet and a lower outlet; 5 for the melting of flat glass, with the upper glass inlet and the lower glass outlet; FIG. 7, the resulting velocity distribution, represented by sections of melt trajectories traveled after 30 seconds, in longitudinal axial section through the melting space of FIG. the trajectory of the closest trajectories for dissolving the grains of sand into the longitudinal axial vertical section through the melting chamber of Fig. 6, for the reference case, Fig. 9 the resulting velocity distribution in the longitudinal axial section through the melting chamber; 6, for the optimum case,

Fig. 10 is a projection of a critical trajectory and other slowest trajectories for dissolving sand grains into a longitudinal axial vertical section through the melting space of Fig. 6, for an optimum case; Fig. 11 a melting space for melting flat glass with a lower inlet and a lower outlet.

FIG. 12 shows the resulting velocity distribution in longitudinal axial section through the melting chamber of FIG. 11, shown by sections of melt trajectories traveled in 30 s, for optimal case; FIG. 13 shows critical and other slowest trajectories for melting sand grains into longitudinal axial vertical section. 11, for the optimum case.

An exemplary embodiment 2 for the manufacture of spectacle moldings is shown in Figures 14 to 16, where the resulting velocity distribution in longitudinal axial section through the melting space shown in sections of melt trajectories traveled in 30 s is shown schematically in Figure 14; critical trajectories and other slowest trajectories for dissolving sand grains into longitudinal axial vertical section through space, for reference case, Fig. 15 the resulting velocity distribution in longitudinal axial section through the melting space shown by melt trajectory sections traveled in 30 s, for optimal case; velocity distribution in longitudinal axial section through melting space shown section of melt trajectories traveled in 30 s, fig. 17 projections of critical and other slowest trajectories for melting sand grains into longitudinal axial vertical section through space, for optimum case.

An exemplary embodiment 3 for the production of container glass is shown in Figures 18a to 22, wherein the melting chamber of Figure 18a is schematically shown in longitudinal section, Figure 18b in cross-section below the enamel level, Figure 19 resulting in longitudinal axial section velocity distribution. Figures of critical and other slowest trajectories for melting sand grains into a longitudinal axial vertical section through the space, for reference case, Fig. 21 shows the resulting velocity distribution in longitudinal axial section. depicted by the melting compartments of enamel trajectories traveled in 30 seconds, for the first optimized case, FIG. 22 shows the projections of critical and other slowest trajectories for dissolving sand grains into a longitudinal axial vertical section through the space, for the first optimized case,

An exemplary embodiment 4 for the production of utility glass is shown schematically in Figs. 23-24, wherein the melting chamber is schematically shown in longitudinal axial section, and Fig. 23 with the side wall burners for reference, and Fig. 24 with vertical heating. electrodes and side burners, for the optimum case.

-5GB 304703 B6

DETAILED DESCRIPTION OF THE INVENTION

W. Trier, Advances in Glass Technology, Plenum Press, 1962, p. 619 shows a typical longitudinal axial sectional view of the flow through a horizontal glass melting furnace without constant temperature circulation in the attached Fig. glass furnace in the presence of temperature gradients, including circulation.

The naturally occurring type of glass flow evident from FIG. 1b has had a significant effect, in particular in the melting portions of glass furnaces, on the melting process and hence on the efficiency of the entire melting apparatus in terms of its performance and energy consumption per melting process. For the melting process, the resulting type had some advantages, in particular the fact that the massive glass return from the temperature maximum to the trunk layer in the initial part of the furnace, as shown by the left circulation circuit in Fig. 1b, brought much needed heat to reaction of raw materials. A second advantage of natural flow was the often present glass return from the flow to the melting temperature region, as shown in Fig. 1b, at the bottom of the right circulation circuit. The return flow returned to the melting process of inhomogeneity, especially the bubbles that were due to the imperfect flow of the melting process. A disadvantage of the established type of flow was the resulting continuous flow of glass from the charge layer to the bottom of the melting furnace, where it moved forward at the lowest temperatures up to the maximum temperature range, where it was only circulated to bring it to high temperatures. The result of this flow was slow homogenization of the glass (dissolution of particles and chemical inhomogeneities) and practical absence of the fining process (bubble output) in a substantial part of the active furnace space at the bottom of the furnace. While the dissolution processes could be completed after the molten glass was brought from the bottom to the surface, the process of removing primary bubbles in the high temperature region at the surface was practically only beginning. Thus, both processes took place substantially in the region after the glass batch reactions, with the dissolution being carried out at the bottom of the furnace for most of the time required at low temperatures. The continuity of the processes (instead of their intensive parallel run) and the high proportion of adverse conditions during the dissolution process were reflected in the high heat losses of the melting process and in the small specific melting performance of the aggregates, which required relatively large devices at higher planned outputs. In addition, it has been shown that the established circulation flow at low specific performance of the melting compartments creates significant volumes of long-term circulating glass in the compartments, in which the melting process is essentially not carried out (dead compartments - overprocessing compartments). This glass is therefore maintained at the melting temperature without its own effect and causes unnecessary heat loss.

Recently, the authors of this application have begun to study in detail the effect of flow patterns on the two most important melting processes, ie dissolving unreacted glass batch particles, which in most cases represent glass sand, and removing bubbles (refining), mostly the slowest melting process [28-35 ], Defined the specific energy consumption and specific melting capacity of a given melting space as the quality criteria of the current melting process. They chose a rectangular horizontal flow space with inlet and outlet as the model melting space with all or part of the front walls. Its diagram is shown in Figure 2, the shape of the melting chamber was simple to achieve the most general results, the dimensions of the equipment were small in accordance with the effort to miniaturize the next melting chamber - length lm, width and glass level 0.5 m. apply the results to other dimensions of the real device. The mathematical model of the melting space with the possibility of wide variability of conditions was chosen as a means of investigation.

Figure 2 is a schematic diagram of a simplified model melting chamber with full inlet and outlet. The appropriate flow pattern was set using linear temperature gradients inserted at the enamel level, the bottom and walls of the space were isolated. Because the dissolution process and the bubble removal process are carried out on different principles, the investigation was performed separately for each process, with a compromise between optimal conditions being chosen in applications, or a separate segment of the equipment would be designed for each process.

-6GB 304703 B6

In order for the results of the monitoring to be well understood, it is necessary to provide a theoretical basis for the investigation, for this application relating to the dissolution of glass sand particles, which is usually a major part of most industrial glasses and is the glass raw material that dissolves most difficultly and last in the glass melt.

For a process without energy recycling, the criteria of specific energy consumption and melting chamber volumetric performance are described by the following equations, which include the process duration (its kinetics) and the effect of the flow pattern separately. The influence of flow character is expressed by a newly introduced variable called the use of melting space, Mo [31, 33-35]:

H ^l d _d 1 pV u _D (1) (2),

where H ° _m is the specific energy consumption [Jkg ^-1 ]; H [, is the theoretical heat required for chemical reactions, phase and modification conversions, and heating of the incoming mixture and the resulting glass to the melting temperature [Jkg ¹ ]; If ^L is the total heat flow through the boundary to the environment [Js' ¹ ]; is the mean dissolution time of all glass sand particles under different time-temperature regimes applied [s]; p is the specific gravity of glass [kg / m ³ ]; V is the volume of the melting chamber [m ³ ]; V is the volume flow of glass through the space assuming completion of the melting process [m ³ s'] and _D is the use of the melting space for dissolution. Here, _D expresses the relationship between the mean time for the process itself, and the theoretical residence time of the molten glass in the melting medium, the so-called geometric time

In the delay, which is equal to the ratio of volume and volume flow through space T _G = V:

at

(3) ·

It can be seen from equations (1-2) that the specific energy consumption is inversely proportional and the volumetric power is proportional to the utilization of the melting space.

The term for the use of melting space in the case of sand grain dissolution is composed of two parts of dead space, where m _G includes closed circulation and regions of almost static glass (eg corners). This value was previously determined, for example, by the transient characteristic method, as mentioned above. / w _D indicates the area where all the grains of sand are already dissolved, but the respective glass is still heated in space (overprocessing). The use of the melting space for the dissolution of sand is then given by:

= (1m _G ) (1m _D ); m _G = ^T ° ^T ; m _D = ^T (4), τ _α τ where Γ is the average residence time of the flowing glass through space, the mean dissolution time of the sand grains under isothermal or near isothermal conditions satisfies: _{D D} = T _D = T _Dcrjt , where T _D is the time needed to dissolve all sand grains at a given or average temperature ar _{/) cr (ř} is the residence time of the molten glass on the fastest (critical) trajectory. in the model melting space under time-temperature regimes on the enamel trajectories (thus, a slight buoyancy force acting on sand particles is not considered).

In particular, when investigating the effect of flow patterns on power and specific energy consumption, the sand grain dissolution time is constant, or the temperature dissolution time temperature is constant, the effect of the very slow glass convection there is not considered. The dissolution times of the glass sand particles are determined experimentally. In order to compare individual cases, a reference state is established. When the reference state is reached, the last - critical - particle is dissolved at the exit of the melting chamber. Technologically, such a state corresponds to the state of a “no reserve” process and the real performance would actually be lower. The resulting specific modeling value is the space utilization value of _D , which is proportional to the space performance (equation 2) and inversely proportional to the specific energy consumption (equation 1) under constant dissolution kinetics. For information, the value of Ud for a melting chamber of the melting chamber type assuming a piston flow is 1 and for an isothermal melting chamber with a parabolic distribution of the glass velocities of 0.445. However, a higher value is only achievable with an ideal liquid, the isothermal flow of the glass being difficult to implement in high-temperature melting rooms, where a multi-stage horizontal temperature difference already causes effective circulation flow and a reduction in _D.

Detailed modeling of the influence of elementary and mixed flow types was performed on the given model melting space, where pure longitudinal circulating flow in both clockwise and anticlockwise directions (circulation in vertical planes parallel to the main-working flow direction) and transverse flow were considered as basic flow types. flow where the circulation takes place in planes perpendicular to the main-working flow direction. The mixed streams then included the types of streams whose intensity ratio was set by the ratios between the inserted horizontal temperature gradients. Both types of longitudinal flow have been shown to result in large dead spaces, where the utilization of the melting chamber was only 0.1 to 0.2, while the introduction of a net transverse flow yielded recovery values of 0.4 to 0.5 due to the disappearance of part dead space. However, the best results were obtained with the mixed flow type, where the rapid forward flow component at the molten glass level was hampered by a small temperature gradient with a higher temperature at the exit and where a relatively intense transverse flow gradient was induced, This optimum flow pattern was characterized by the spiral glass trajectories, as shown in Figure 3, and a very low dead space value m _G as well as a partially reduced dead space value m _D (see equation (4)).

Further research has shown how this optimal type of flow and its setting conditions change as the independent variables change, such as the ratio of transverse to longitudinal flow, total circulation flow rate, glass sand particle dissolution time, and melting space length. The influence of the glass properties and the glass layer height can then be included in the influence of the overall flow rate. The width of the space, while maintaining temperature gradients, will not substantially affect the utilization. For each pair of dissolution time of the glass sand particles in a given glass and the length of the melting chamber while maintaining the glass layer height, the maximum value of the melting chamber utilization for the dissolving process can then be found. These maximum values ranged above 0.5 over a wide range of sand dissolution times and melting channel lengths; in most cases even between 0.6 and 0.8, which were significantly better than can even be achieved in the isothermal melting space. The dependence of these maximum utilization values on both mentioned quantities in the model melting space is shown in Figure 4. Figure 4 shows the dependence of the maximum utilization value of the melting space on the melting time of glass sand for different lengths of the melting space. It is apparent from the depicted dependencies that the maximum utilization rates of the melting chamber increase with both the dissolution time of the sand and the length of the melting chamber. At the same time, laws have been found governing the temperature gradient values that need to be set to achieve optimal utilization of the melting space.

-8EN 304703 B6

The obtained results proved that it is possible to find and define the optimal type of spiral flow in terms of the dissolution of glass sand particles and to define the optimal conditions for achieving it. There were also defined patterns of changes in optimum utilization and optimal conditions for changes in input parameters. Thus, the prerequisites for transferring results to real smelting spaces were obtained.

Example 1 (Figures 5 to 13)

However, in order to apply the results, it is necessary to define a specific melting space, specific energy sources, their distribution and heat output to allow the desired type of spiral flow to be set, which is the subject of the present invention.

Achieving the goal is to design a special glass melting space for dissolving glass batch components, especially glass sand, ie to design the shape and suitable dimensions of the melting space, its typical material composition, the way of heating and distribution of heat sources in the melting space, heat so that the melting process takes place at a predetermined average temperature and to achieve a spiral flow type that ensures high utilization of the melting space for the glass melting process. To achieve this state, the prescribed process of mathematical modeling of the melting space is used together with the calculation of its utilization.

In carrying out the process according to the invention, molten glass containing undissolved glass sand particles and located in a horizontal flow-through melting space, an energy source, typically by heating electrodes or industrial glass burners, is treated so that a temperature distribution is created in the molten glass type of flow in the direction of glass flow through the space, thereby achieving high utilization of the given melting space for the dissolution process, thus also high space performance and low specific energy losses.

A cuboid appears to be a special space, the length of which is generally greater than its width and the level of the glass level in the melting space of the glass furnace. The melting chamber is horizontally oriented, flowable and separated and comprises a bottom I, a foundation wall 2 and an opposing rear flow wall 3 and opposed side walls 4, a vault 5 and a transverse dam wall 7 immersed in the glass 6 in the melting chamber. in at least one row along the longitudinal axis of the melting chamber or parallel to this longitudinal axis, between the loading wall 2 and the transverse dam wall 7 in the glass 6 or the transverse row 9 of energy sources in the glass melting section 6 to induce spiral flow of glass 6 with a circular moving across the melting portion. The energy sources are preferably heating electrodes 10 or industrial burners 11.

The mixture of molten glass 6 with inhomogeneities enters the melting chamber through the upper inlet or the lower inlet 12, which may be tapered or occupy the entire width of the melting chamber and may have different heights. However, too narrow an inlet 12 and an outlet 13 affect the set flow pattern in the space and it is therefore recommended that the inlet 12 or the outlet 13 do not occupy less than about 20% of the front loading wall 2 or the rear flow wall 3. The melting space is lined with a refractory lining used in glass melting furnaces. According to modeling results, electrical heating by means of electrodes 10, which are generally molybdenum, has proved to be the best heating. However, heating by gas or oil burners JT is also applicable, especially in combination with electric heating. A schematic diagram of a typical electrically heated melting chamber is shown in Figure 5.

The melting process takes place in the range of temperatures suitable and common for melting industrial glass, the specific temperature depends on the type of glass, but for conventional glass the average melting temperatures of 1300 to 1500 ° C have to be taken into account. Continuous flow is ensured by the inflow of glass enamel mixture with solid and gaseous inhomogeneities from the previous space, where the inlet mixture of glass raw materials is heated and melted and taken to the next space where homogenization is completed, bubbles are removed or only stabilize the temperatures and take out the finished glass. The performance of the melting chamber can be adjusted in addition to adjusting the appropriate type of spiral flow object of the present invention by particle size distribution (sand grains), by adjusting the composition of the resulting glass and by the average temperature in the dissolving chamber. In the melting chamber of the glass furnace, the same amount of glass 6 is maintained by inlet and outlet.

A typical shape and arrangement of heat sources, electrodes 10, in the proposed dissolution module is shown in Figure 5.

The basis of the present invention is to achieve a certain type of spiral flow in the flow space by arranging heat sources, or dimensioning the glass furnace insulation so that a transverse circulation flow occurs in the melting space under both factors simulating the optimal type of spiral flow temperature gradients. This transverse circulation flow has a partially suppressed longitudinal longitudinal component of the glass melt movement at the surface in order to reduce the differences between the residence times of the glass 6 on different trajectories. This can be achieved, for example, by a longitudinal row of electrodes 10 positioned generally from the bottom of the glass furnace so as to form a longitudinal thermal barrier either in the longitudinal axis of the melting chamber, where the electrodes 10 will also be located, or side walls 4 of the melting chamber, where a longitudinal row of electrodes 10 would also be located. More than one longitudinal row of electrodes 10 can be accommodated in melting rooms designed for high throughput, but this arrangement seems less advantageous for slowing the horizontal velocity component at the surface. In order to better achieve the desired type of spiral flow, it is advisable, but not necessary, to place other sources in the space, eg a transverse row 9 of electrodes 10, which better prevents the fast forward of the flow component at the surface or prevents longitudinal circulating flow of glass. burners 11 must also be arranged above the surface of the glass furnace, either by placing the burners 11 in the furnace vault 5 or in the side walls 4 and orienting them so as to form a temperature barrier in the melting chamber along the longitudinal axis of the glass furnace or one of the side walls 4. When using the burners JT as heat sources, it is possible to simultaneously use electrodes 10, predominantly along the longitudinal axis of the melting chamber or at one of the walls that will support the formation of a longitudinal temperature barrier. The distribution of energy into heat sources or the necessary insulation of the melting chamber or its parts, ensuring the optimum character of the spiral flow, must be set by targeted mathematical modeling of the melting chamber. For modeling it is necessary to determine experimentally the dependence of the glass melting time on temperature in the expected melting temperature range. The same temperature dependence can be used for glasses of similar composition and the same grain size of glass sand. The melting capacity and specific energy consumption of the melting space operating in the critical mode, i.e. without reserve, are determined by modeling, i.e. the last dissolving particles are dissolved just at the exit 13 of the melting space. The energy distribution on the sources is gradually adjusted so that the calculated value of the utilization of the melting space reaches the maximum achievable value or is the highest value in a technically achievable arrangement. During modeling it is possible to make corrections also in the arrangement of heat sources, but always in order to create the desired type of spiral flow. Required space utilization values should be at least about 0.4, but rather above 0.5.

It is, of course, very useful to estimate how the spiral flow and the corresponding use of the melting chamber will behave at the extreme setting values, i.e. at very low or very high transverse and longitudinal flow intensities ratios with potential return at glass level 6, low or very high. high intensities of glass circulation 6, with very slow or very fast dissolution or with short or very long melting spaces.

A very low transverse flow ratio when there is a longitudinal flow will always result in a decrease in utilization and will approach zero at increasing longitudinal flow intensities. Conversely, at very high transverse to longitudinal flow intensities, the utilization value will approximate and then remain around 0.5.

In the region of the ratio between the flow intensities of the glass 6, which is expressed by the transverse to longitudinal temperature gradient of 5 to 20, the utilization will reach a maximum value of 0.6 to 0.8. Here, the technologically advantageous area is characterized by the maximum value of space utilization. In another region of the ratio of flow intensities, it does not make sense to operate at virtually any total flow intensities, dissolution rates or melting chamber lengths.

The maximum utilization values of the melting space in this ratio range are 0.445 at zero circulating flow rate, with glass 6 flowing through the isothermal rectangular melting space, and gradually increasing to a total circulating flow rate of 0.6 to 0.8 at commonly obtainable intensity values. circulating, and reach values of 0.5 to 0.6 at high circulating intensities, which, however, are not achieved under normal conditions. The maximum utilization values in the region of the optimum ratio between the transverse and longitudinal flow intensities are little dependent on the dissolution rate and are within a wide range between 0.6 and 0.8. The very short melting chamber channels show low utilization rates because they do not suffice to develop a spiral flow pattern, the values decrease to 0.4 at a melting chamber length of 0.5 m, and will approach 0.4 for even shorter spaces. For very long melting chamber channels, the utilization value will be kept relatively high, around 0.6 and above, but the necessary optimum ratio between transverse and longitudinal flow intensities will increase disproportionately.

The specific aim is to transfer the character of the temperature field created in the model melting space by means of temperature gradients to the proposed specific melting space, differing from the model one in particular by exhibiting temperature losses through interfaces and heated by specific sources, eg electrodes 10 or burners 11 in such an assembly. and the distribution of the supplied energy, a temperature field is created within the space which induces the desired spiral type of glass flow 6, characterized by high utilization of the melting space and corresponding flow pattern in the model device. This object is achieved by designing a first melting chamber arrangement based on the knowledge of the original model apparatus by mathematically modeling the temperature and velocity field of the glass melt and the course of sand grain dissolution on the enamel trajectories generated by the inserted energy into ordered heat sources and losses in the proposed variant. The performance of this arrangement is adjusted after the first calculation so that at the predefined and maintained average temperature in the melting chamber, the last glass sand grain melts just at the outlet 13 of the melting chamber, i.e. that the chamber operates without a melting margin. This state is called critical.

Calculation gives the time of dissolution of sand grains on the most disadvantageous critical path, even _Dc rit, through space (the grain dissolves just at the exit of the space and the given trajectory determines the maximum melting

IN

Tg = - performance based on critical state) and corresponding geometric residence time V, sand dissolution time on other monitored td trajectories (of which there are 10 ⁵ or more) and their mean dissolution time of glass sand particles, and from distribution of glass residence times on monitored trajectories its mean residence time in critical space. Using the equation (4), the corresponding use of the space ud is then obtained, and the specific energy consumption for heat losses is calculated from the power and energy data.

The first arrangement may be, but does not necessarily have to be, reference and simulates an arrangement corresponding to a conventionally heated device that exhibits low space utilization value. The results of the calculations with the expected advantageous type of flow with high utilization of the melting space (hereinafter the space) are then compared with the reference ones and the modified further variants are derived from their comparison. As already mentioned, it is not always necessary to calculate the reference setting, and when searching for the optimum spiral flow, the following calculations can be based only on the space utilization values obtained, where good values start at around 0.4. The aim is then to get the highest Ud value of the utilization of the melting space between about 0.6 to 0.8.

The second arrangement is also based on the results of modeling on the melting chamber with pre-set temperature boundary conditions, however, the location and dimensioning of selected heat sources or the dimensioning of the interface insulation are already set to better achieve the described advantageous type of spiral flow. In the first variant, the use of the melting space in this variant, the capacity of the space and the specific energy consumption are calculated according to the above-mentioned procedure and, if necessary, compared with the reference values of the first arrangement. According to the results, the arrangement of sources, eventually insulation and distribution of supplied energy will be adjusted in the direction in which the utilization is expected to increase. The direction of the adjustment is determined by the general rules already obtained governing the use of the melting space. In the second variant, a second set of recovery, specific energy consumption and power is obtained. Where appropriate, the design of improved variants shall continue until the maximum achievable value of space utilization is achieved.

Thus, the process for designing a high utilization melting chamber is broken down into the following steps:

1. Determination of temperature dependence of sand grain dissolution time in laboratory and determination of temperature dependence of average dissolution rate on temperature.

2. Design of basic dimensions and method of heating of new melting space using common design knowledge and results from original model space based on requirements

3. for performance and with the necessary melting conditions (average temperatures).

4. Calculation of the utilization of the melting space in the reference arrangement corresponding to the conditions in a classically operated plant. This step is not inevitable.

5. Calculation of utilization in the melting chamber with proposed parameters corresponding to the expected desired type of spiral flow.

6. Repeated adjustments of conditions and calculations leading to the arrangement and conditions at which the maximum utilization of the melting chamber and its corresponding melting capacity and specific losses are achieved in terms of theory and practice.

Special melting room for melting of glass sand grains in float glass working at an average temperature of 1400 ° C and with the required output of at least 20t / 24h. In view of the high specific powers obtained in the previous model space with the set temperatures, a relatively small block shape with a length of 2m, a width of 1m and a glass level of 6 0.5m was designed. A detailed diagram of this space is shown in Figure 6. The melting space is preceded by a molten glass space which is not the subject of the present invention. The walls of the melting chamber are composed of layers of refractory material, the vault 5 being low, slightly arched. The inlet 12 is located along the entire width of the melt either at the bottom I or at the molten glass level 6 and occupies 20% of the front loading wall 2. The outlet 13 is then formed by a flow at the molten glass level 6 over the entire width of the melting space. % of the rear flow wall. The melting chamber is heated by a longitudinal row of 6 molybdenum electrodes 10 positioned from the bottom and in the axis of the melting chamber. The electrodes 10 are connected in a manner wherein the row of electrodes is divided into three pairs, each pair comprising one transformer. This makes it possible to divide the power of the electrodes into three zones and thus set the desired power and therefore temperature gradient. The method makes it possible to regulate the energy supply to the molten glass in the individual parts of the furnace and thus to adjust the nature and intensity of the natural flow in the melting chamber.

Figure 6 is a detailed diagram of the proposed space for melting flat glass with the upper inlet 12. In the first phase of modeling, the energy distribution at the electrodes 10 was simulated to simulate the type of flow common in conventional glass furnaces (reference setting). The inlet 12 to the melting chamber was at the molten glass level 6. By concentrating energy on electrode # 5

- 12GB 304703 B6 and 6, a transverse thermal barrier is simulated which causes the usual longitudinal circulation flow. The distribution of energy on electrodes in% is given in Table 1.

Table 1

Energy distribution on the electrodes 10 according to their numbering in Figure 6 at the reference heating setting and with the upper input 12.

Electrodes 1 + 2 3 + 4 5 + 6 Power [kW] 0 0 118.6

The flow pattern was controlled to match that known from conventional glass melting furnaces.

In Figure 7, the resulting velocity distribution in longitudinal axial section through the melting space is shown by sections of glass trajectories traveled in 30 s, representing the reference case.

Critical and other disadvantageous dissolution paths have also been obtained, the projections of which in longitudinal axial vertical section through the melting space are shown in Figure 8, which illustrates a reference case.

The resulting velocity distribution and trajectory shapes correspond to the results obtained on conventional devices, so the reference case is qualitatively set correctly.

For the dissolution of sand, experimental data were obtained by repeated laboratory melting of the glasses and by counting the undissolved grains of sand in the resulting glass samples obtained in time sequence at temperatures of 1300 to 1500 ° C and at intervals of 50 ° C. For an average sand grain dissolution rate of an initial maximum grain diameter of 0.5 mm, an empirical equation [36] was obtained: v _Diss = 1.56x10 ^'18 exp (0.0153T) [ms ¹ ], where T is the temperature in K.

This equation was applied to the dissolution process taking place in the melting chamber with temperatures and flow set to the reference case and later to other cases.

The following values were obtained by modeling of the final variant describing the classical setting, complying with the average temperature of 1400 ° C and processing:

Average temperature: 1400 ° C.

Dimensions of the melting chamber 2x1x0,5 m - length, width, height.

Entry 12: Homes.

Electric heating output Ε: 118,6 kW.

Critical power V: 6.79x10 ' ⁵ m ³ s'' = 13.65 t / 24h = 6.82 t / (24hm ² ).

The average residence time of the glass in the space ΰ ΐ3 888 s.

Average dissolution time of sand grains «d; 2451 s.

Geometric residence time ^T G = V: 14724 s.

Dead space fraction by enamel circulation mg. 0.050.

Dead space fraction after dissolution of sand grains m _D : 0.825.

Share of melting space utilization at _D ·. 0.166.

- 13 GB 304703 B6

Specific loss Vp: 751 kJ / kg.

The measured reference power of the melting module 6.82 t / (24hm ² ) is high compared to that of conventional glass furnaces, but it should be noted that in this case the set average temperature of 1400 ° C is relatively high; the highest possible power - critical - when there is no melting reserve in the space and that the power is only related to the completion of the dissolution of the sand grains. With a 50% margin, the specific power is only 3.41 t / (24hm ² ) and this value is already realistic. The same situation applies to specific losses, which at 50% reserve would be 1502 kJ / kg, which is also a realistic value due to the high average melting temperature of 1400 ° C.

The determined dead-space fraction rriQ is much lower than expected for a given type of flow, and is measured, for example, by measuring the furnace transition characteristics. However, checking the furnace residence time distribution curve in the furnace did not reveal irregularities on the curve, which could reveal recycling of some continuous trajectories due to numerical calculation errors (increasing the «value and decreasing the calculated value / w _G ). The reason for the low dead space values m _G is that the transverse temperature barrier was only adjusted by the power on the axially positioned electrodes 10. This has already produced some transverse flow and has resulted in a decrease in the m _G value. Using a conventional transverse temperature barrier would make the use of the melting space even lower.

Next, the energy was adjusted on the individual electrodes 10 to achieve the desired type of spiral flow.

At the final setting, see Table 2, substantial changes in the glass flow pattern and the typical spiral nature of the critical and near glass trajectories as shown in Figures 9 and 10 are observed. in 30 seconds, and is the optimum case. Figure 10 shows the projections of critical and other slowest trajectories for dissolving sand grains into a longitudinal axial vertical section through space, and is an optimal case.

Table 2

The energy distribution on the electrodes 10 according to their numbering in Figure 6 at the optimal variant of the heating setting and at the upper input 12.

Electrodes 1 + 2 3 + 4 5 + 6 Power [kW] 33.5 39.4 46.6

The final variant with the power distribution shown in Table 2 gave the optimum result: Average temperature: 1400 ° C.

Dimensions of melting chamber 2x1x0,5 m- length, width, height.

Input 12: Upper.

Electric heating output Ε: 119,5 kW.

An average transverse temperature gradient of 45 K / m, an average longitudinal gradient of 8K / m, an average transverse to longitudinal gradient of 5.6.

Critical power y: 2,63x10 ^"4 m ^{3 _1} = 52.86 t / 24h = 26.43 t / (24hm ^2).

The average residence time of the glass in the space ϋ 3760 s.

- 14GB 304703 B6

Average dissolution time of sand grains ^T D: 2498 s.

F

Geometric residence time + G = F: 3807 s.

Dead space fraction by enamel circulation ihq: 0.012.

Podíl dead space after the dissolution of the sand grains _D · m. 0.336.

Melting space utilization ratio for _D : 0.656.

Specific Loss Vp: 196kJ / kg.

This result already shows a substantial improvement due to the setting of a more efficient type of flow in the melting chamber. The utilization of the melting space of _D increased by 3.95x compared to the reference case, the melting capacity of the space increased by 3.87x and the specific losses decreased by 3.83x. Considering 50% of the melting reserve, the space output would be 26.43 t / 24h and the specific dissolution capacity would be 13.22 t / (24hm ² ). The conditions for the required melting chamber capacity were met.

When operating an optimized glass flow device, the problem arises in the occasional leakage of the unsold batch from the level of the previous space through the upper inlet into the dissolution chamber. This problem was solved by placing the inlet 12 in the area at the bottom I of the dissolution chamber, as shown in Figure 11.

In this case, it will be demonstrated to achieve optimum flow settings using two variants, the first and the last variant - optimal. The first setup was based on the results obtained on the original model device with the set temperature field [33-34]. In the first variant, virtually the same power has been set for all electrodes 10 as shown in Table 3.

Table 3

The energy distribution on the electrodes JO according to their numbering in Figure 11 at the first variant of the heating setting and at the upper input 12.

Electrodes 1 + 2 3 + 4 5 + 6 Power [kW] 40.6 40.6 41.8

The results of the calculation of the first variant are as follows:

Average temperature: 1400 ° C.

Melting chamber dimensions 2x1x0,5 m - length, width, height.

Entry 12: Lower.

Electric heating output E: 122.9 kW.

Average transverse temperature gradient 40 K / m, average longitudinal gradient 8K / m, average transverse to longitudinal gradient 5.

Critical power É: 2,49x10 ' ⁴ m ³ s ^_1 = 50,11 t / 24h = 25,05 t / (24hm ² )

Average residence time of glass in the space: 3988 s.

Average time of sand grain dissolution: 2531 s.

F

Geometric residence time ^T G = F: 4011 s.

- 15GB 304703 B6

Dead space fraction by mc 'glass circulation. 0.006.

Dead space fraction after dissolution of sand grains m _D \ 0.365. Share of utilization of melting space at _n \ 0,631.

H ^L = ^ -

The flow pattern with the change in location of the inlet 12 has not changed. Modeling continued until the optimum case was reached.

The optimum case is illustrated by Table 4 and Figures 12 and 13. Figure 12 shows the resulting velocity distribution in longitudinal axial section through the melting space shown by sections of glass trajectories traveled in 30 s as an optimal case. Figure 13 shows the projections of critical and other slowest trajectories for dissolving sand grains into a longitudinal axial vertical section through space, an optimal case.

The energy flow settings in the optimal case are shown in Table 4.

Table 4

The energy distribution on the electrodes 10 according to their numbering in Figure 6 at the optimum heating setting and at the inlet 12 at the bottom 11.

Electrodes 1 + 2 3 + 4 5 + 6 Power [kW] 34.8 41.0 48.4

The results of the last - optimal - variant calculation are as follows:

Average temperature: 1400 ° C.

Melting chamber dimensions 2x1x0,5 m - length, width, height.

Entry 12: Lower.

Electric heating output E \ 124.2 kW.

Average transverse temperature gradient 45 K / m, average longitudinal gradient 7K / m, average transverse to longitudinal gradient 6.4.

Critical power F _: 2.54x10 ⁴ mV = 51.05 t / 24h = 25.53 t / (24hm ² ).

Average residence time of glass in the space prostoru 3915 s.

Average dissolution time of sand grains D): 2545 s.

Geometric residence time ^T G = F: 3943 s.

Dead space fraction by glass circulation m _G : 0.007.

Dead space fraction after dissolution of sand grains m _D : 0.350. Melting space utilization ratio for _D : 0.646.

Specific loss of ap _: 210 kJ / kg.

A comparison of the first and optimal variants shows that the first variant envisaged differs little from the optimal variant. Thus, the results are less sensitive to small changes if there is a well-founded idea of what is to be achieved.

-16GB 304703 B6

For comparison, values from the reference case were used with the inlet located at the surface. According to the calculation, space utilization increased 3.89x, melting capacity increased 3.74x and specific losses decreased 3.58x. Power at 50% melting reserve would reach 25.53 t / 24h and specific power 12.76 t / (24hm ² ). The values are only slightly worse than in the case of a level inflow, the performance of the space exceeds the required 20t / 24h and the last arrangement can be used with both inputs.

Example 2 (Figs. 17 to 17)

Special space for melting grains of glass sand in glass for the production of spectacle moldings operating at an average temperature of 1300 ° C and with the required output of at least 8t / 24h.

The same special 2 m length, 1 m width and 0.5 m layer height is available for melting as in Example 1, the inlet 12 to the melting compartment is located at the bottom 1 (see Figure 11), heating is again electric, heat sources however, they allow an average dissolution temperature of only 1300 ° C. Due to the similar composition of the glass and the same raw materials used, the same temperature dependence of sand grain dissolution time was used as in Example 1. A reference case was also solved, although it was assumed that lowering the average temperature would not have a significant effect on melting space utilization [34] The resulting reference variant yielded the following distribution of electrical power over the electrodes 10.

Table 5

Energy distribution on the electrodes 10 according to their numbering in Figure 6 at the reference heating setting.

Electrodes 1 + 2 3 + 4 5 + 6 Power [kW] 0 0 106.5

The resulting type of flow and the course of critical and similar trajectories did not differ substantially from the flow at 1400 ° C at the reference setting, as shown in Figures 14 and 15. s as a reference case. Figure 15 shows the projections of critical and other slowest trajectories for dissolving sand grains into a longitudinal axial vertical section through space as a reference case.

The results of the solution of this reference case are as follows:

Average temperature: 1300 ° C.

Dimensions of the melting chamber 2x1x0,5 m - length, width, height.

Entry 12: Lower.

Electric heating output £: 106.3 kW.

Critical power F: 3.78x10 ' ⁶ mV ¹ = 0.76 / 24h = 0.38 t / (24hm ² )

Average residence time of glass in the space 63206 s.

Average dissolution time of sand grains «d: 10131 s.

- 17GB 304703 B6

F

Geometric residence time ^T G = F: 264355 s.

The proportion of dead space through the circulation of enamel we. 0,761.

Percentage of dead space after melting grains of miy sand. 0.840.

The utilization rate of the melting space for _D : 0.038.

_H i ₌

Specific Loss Ep _; 12080 kJ / kg.

The case is very disadvantageous, the lower entrance to space plays a big negative role. There has already been a large proportion of dead space w ₍ "also the losses are extremely large, the critical trajectory and others are moving close to the bottom £ at low temperatures, the power is then very small. The case cannot serve as a reference because of its extreme disadvantage). of the flow type to the efficiency of the dissolution process.

In a further procedure, the powers on the electrodes 10 have been adjusted to create the desired type of optimum flow in the melting chamber. The power distribution is shown in Table 6, while the speed distribution and critical trajectory along with similar ones are shown in Figures 16 and 17.

Table 6

Energy distribution on the electrodes 60 according to their numbering in Figure 6 at optimal heating settings.

Electrodes 1 + 2 3 + 4 5 + 6 Power [kW] 29.4 34.7 41.0

Figure 16 shows the resulting velocity distribution in a longitudinal axial section through the melting space shown by sections of glass enamel trajectories traveled in 30 s, which is the optimal case.

Figure 17 shows projections of critical and other slowest trajectories for dissolving sand grains into longitudinal axial vertical section through space, representing an optimal case. The results of the optimal variant solution are as follows:

Average temperature: 1300 ° C.

Dimensions of melting chamber 2x1x0,5 m - length, width, height.

Entry 12: Lower.

Electric heating output E: 105.2 kW.

Average transverse temperature gradient 50 K / m, average longitudinal gradient 7K / m, average transverse to longitudinal gradient 7.1.

Critical power Ý: 5,59x10 ' ⁵ m ³ s ^_1 = 11,23 t / 24h = 5,62 t / (24hm ² )

The average residence time of glass in the space «17025 s.

Average dissolution time of sand grains d d; 10599 s.

F

Geometric residence time = F: 17895 s.

The proportion of dead space through the circulation of enamel we. 0,049 s.

Dead space fraction after sand grain dissolution zw _o : 0.378.

-18GB 304703 B6

Share of melting space utilization for _D : 0.592.

Vp specific losses: 809 kJ / kg.

The resulting values meet the assumption of power, which at the assumed 25% melting reserve reached 8.42 t / 24h for the whole plant, ie 4.21 t / (24hm ² ). The specific losses in kJ / kg are again very low as expected.

Example 3 (Figs. 18-22)

It is necessary to design a special space for dissolving the glass sand in the white container glass, which will achieve a power of at least 3001/24 h at an achievable average melting temperature of 1425 ° C. The required energy was to be supplied as needed by both the gas burners 11 and the electrodes 10, but it was sufficient to use only the electrodes JO to cover the losses. A melting space of 6.57 m long and 2 m wide with a melt layer thickness of 1 m, with a total volume of 146 m ^3, will be designed for dissolution. A diagram of the space with the proposed heating of the electrodes 10 in both reference and optimized cases and with the inlet 12 at the bottom of the inlet face is shown in Figure 18a (vertical section along the longitudinal axis) and 18b (horizontal section below the surface). In more detail, Figs. 18a, 18b show a schematic of a proposed melting chamber with heating of the electrodes 10 and the location of the electrodes 10 in sections XZ (a) and XY (b).

Table 7 shows the energy distribution of the electrodes 10 according to their numbering in the figure over their sources in the reference arrangement even in the first optimized case.

Table 7

The energy distribution on the electrodes according to their numbering in Figure 18 at the reference and first optimized variant of the heating setting.

Electrodes 1-2 3-4 5-6 7-8 9-10 11-12 13-14 15-16 20-21 22-23 23-24 25-26 Power Ref. 0 0 0 0 0 0 0 0 117.7 117.7 117.7 117.7 IRwJ Qpt. 14.8 19.7 24.6 39.4 49.2 49.2 49.2 49.2 49.2 49.2 49.2 49.2

The resulting velocity distribution in the longitudinal axial section through the melting space shown by the 30-second melt trajectory sections in the reference case is shown in Figure 19 and the projections of critical and other slowest trajectories for dissolving sand grains into the longitudinal axial vertical section through the space are also in the reference case.

Figure 19 shows the resulting velocity distribution in longitudinal axial section through the melting space shown by sections of enamel trajectories traveled after 30 s as a reference case.

Figure 20 shows the projections of critical and other slowest trajectories for dissolving sand grains into a longitudinal axial vertical section through space as a reference case.

The results of the reference case are as follows:

Average temperature: 1425 ° C.

Entry 12: Lower.

-19GB 304703 B6

Dimensions of melting chamber 6,57x2x1,0 m - length, width, height.

Heating power: 471.0 kW.

Critical power V: 2,20x10 ' ⁴ mV ¹ = 44,1 t / 24h = 3,35 t / (24hm ³ )

Average residence time of glass in the space prostoru 36 450 s.

Average dissolution time of sand grains «d: 2433 s.

F

Geometric residence time ^r c = F: 59 875 s.

Dead space fraction by glass circulation m _G : 0.391.

Dead space proportion after dissolution of sand grains m _D : 0.933.

Melting space utilization ratio for _D : 0.041 io Specific losses _: kJ / kg.

The resulting values characterize well the classic glass melting furnace. The relatively high specific power is again given by the fact that it is the critical (maximum possible) power of the space and the process only involves the dissolution of sand grains.

In the next procedure, based on past calculations on the model melting space and the experience gained, a new distribution of the energy supplied to the electrodes 10 has been proposed, which is shown in Table 7 for the optimum case. The aim was again to produce the desired spiral glass flow. The resulting velocity distribution in the longitudinal axial section through the melting space shown by the tra20 sections of glass engravings in 30 s in the first optimized case is shown in Figure 21 and the projections of critical and other slowest trajectories for melting sand grains into the longitudinal axial vertical section Figure 22.

The results of the first optimized case are as follows:

Average temperature: 1425 ° C.

Entry 12: Lower.

Dimensions of melting chamber 6,57x2x1,0 m - length, width, height.

Heating power: 492.3 kW.

An average transverse temperature gradient of 55 K / m, an average longitudinal gradient of 10 K / m, an average transverse to longitudinal gradient of 5.5.

Critical power: 2.97x10 ' ³ m ³ s'' = 597 t / 24h = 45.4 t / (24hm ³ ).

Average residence time of glass in space ^τ : 3994 s.

Average dissolution time of sand grains «d; 1795 s.

F

Geometric residence time ^t g = F: 4419 s.

Dead space fraction by glass circulation m _G : 0.096.

Dead space fraction after dissolution of sand grains m _D : 0.551.

The utilization rate of the melting space for _D : 0.406

Specific losses - 71.2 kJ / kg.

The resulting values provide an unexpectedly high dissolution performance of the melting chamber. This is due to an increase in the utilization of the melting space by one order compared to the reference case. Lower values of the average dissolution time of the sand grains show that the dissolution in the optimized case took place under more favorable temperature conditions. The consequence of high performance devices are very

-20GB 304703 B6 Low Loss. If we add about 16% of the melting reserve, the space would provide a dissolution capacity of 500 t / 24h. However, a utilization value of 0.41 shows that the space flow can still be optimized.

In subsequent steps, the melting power distribution on the electrodes 10 has been altered to extend the residence time of the glass that corresponds to the critical trajectory. Two other cases with optimized energy distribution to individual electrode pairs were calculated. The second variant achieved a significant improvement in utilization, the third variant differed very little from the previous one, thus the utilization approached the optimal value. The third option was thus taken for the final. The distribution in the third optimized variant is in Table 8.

Table 8

The energy distribution on the electrodes 10 according to their numbering in Figure 18 at the third optimized variant of the heating setting.

Electrodes 1-2 3-4 5-6 7-8 9-10 11-12 13-14 15-16 20-21 22-23 23-24 25-26 Performance [%] Ref. 0 0 0 0 0 0 0 0 25 25 25 25 Opt. 10.0 9 9 8 8 7 7 6 9 9 9 9

The resulting velocity distribution in the longitudinal axial section through the melting chamber and the projections of the critical and other slowest trajectories for dissolving sand grains into the longitudinal axial vertical section through the space are very similar to the first optimized case.

The results of the third optimized case are as follows:

Average temperature: 1425 ° C.

Entry 12: Lower.

Dimensions of melting chamber 6,57x2x1,0 m - length, width, height.

Heating power: 507 kW.

Average transverse temperature gradient 55 K / m, average longitudinal gradient 8 K / m, average transverse to longitudinal gradient 6.9.

Critical power É: 4.39x1dVs ¹ = 881 t / 24h = 67 t / (24hm ³ )

Average residence time of enamel in the space «; with.

Average time of sand grain dissolution: 1782 s.

IN

Geometric retention time of molten glass ^T ř? = F: 2994 sec.

Dead space fraction by glass circulation m _G : 0.164.

Dead space fraction after melting grains of sand my · 0.288.

Melting space utilization ratio for _D : 0.595 Specific losses: ⁼ 49.7 kJ / kg.

The resulting values show extremely high performance and very low specific losses. The proposed space with optimized spiral flow therefore has a very high ability to dissolve glass sand even after considering a considerable melting margin. The case shows that the dissolution of glass sand in a given space under given conditions cannot very likely become an event limiting the intensity of the entire melting process.

-21 GB 304703 B6

Example 4 (Figures 23 to 24)

There is a melting space heated by three pairs of cross-burners 11 for melting soda-lime glass and processing by pressing into utility glass products. The device has a length of 6 m and a width of 2 m in the melting section. The glass level 6 is 0.6 m. The average melting temperature is around 1400 ° C. A diagram of half of the original apparatus is shown in Figure 21. Figure 21 shows the original glass melting furnace in longitudinal axial section. In the original configuration, the heating energy was distributed to the individual burners 11 according to Table 9. The numbering in the table is from left to right as shown.

Table 9

The energy distribution over the three pairs of burners 11 according to Figure 23 from left to right at the original burner setting JT and the reference case is as follows:

Output of the first pair of burners 11: 637 kW.

Output of the second pair of burners 11: 700 kW.

Output of the third pair of JT burners: 750 kW.

Total burner output: 2087 kW.

Electrode input: 0 kW.

The results of the reference case are as follows:

Average temperature: 1400 ° C.

Input 12: With surface charge.

Dimensions: length 7.2 m in total, length of melting section 5.2 m, width 1.65 m, enamel depth 6 is 0.6 m.

Critical power: 6.47x10 ' ⁵ mV ¹ = 2.52 t / (m ³ 24h) = 13 t / 24h.

at

Geometric residence time ^T G = F: 79598 s.

Share of melting space utilization at _D ·. 0,059.

/ 7 Ul '- ..

Specific energy consumption *: 13866kJ / kg.

The resulting values indicate a small space utilization, which is also reflected in the low melting capacity of the plant. In the present arrangement of the burners 11, however, it was not possible to substantially influence the flow pattern in the desired direction. Therefore, the heating system has been reconstructed by placing 14 vertical electrodes 10 from the bottom I in the longitudinal axis of the melting chamber. Thus, the necessary longitudinal temperature barrier in the glass melt and the desired type of spiral glass flow have been created. Dissolution of sand grains was considered a critical process. The resulting arrangement of the melting process is shown in Figure 24 and the energy distribution between the burners 11 and the electrodes in Table 10. By a new setting, the transverse spiral flow required was achieved in the region of the electrodes 10. Figure 24 shows the arrangement of the burners 11 in the melting chamber in an optimized case.

-22EN 304703 B6

Table 10

Energy distribution to burners according to their numbering in Figure 22 in optimized torch and electrode settings.

Electrode input: 1400 kW (electrodes 1-2 -> 308 kW; electrodes 3-4 -> 266kW; electrodes 5-6 -> 210kW; electrodes 7-8 -> 168kW; electrodes 9-10 -> 12kW; electrodes 11 -12 -> 70 kW; electrodes 13-14 -> 70kW; electrodes 15-18 T> 98kW)

Burner output: 16.8 kW

The results of the optimized layout are as follows:

Average temperature: 1425 ° C

Input J_2: With surface charge.

Dimensions of the melting chamber: length 7.2 m in total, length of the melting section 5.2 m, width 1.65 m, enamel depth 0.6 m.

Heating output: 1400 kW on electrodes 10, 16.8 kW on burners li ·

An average transverse temperature gradient of 55 K / m, an average longitudinal gradient of 12 K / m, an average transverse to longitudinal gradient of 4.6.

Critical power V: 1.81x10 ' ⁴ mV ¹ = 7.05 t / (m ³ 24h) = 36.3 t / 24h F

Geometric residence time = F: 28453 s.

The share of utilization of the melting space at _n \ 0.239.

Π t / - “Γ7—

Specific energy consumption Fp: 3335 kJ / kg.

The melting power of 30t / 24h can be achieved at the given setting in Figure 24 and Table 10 at about 17% reserve. This reserve is not too high, but at steady-state operates sufficient. The specific melting capacity of 3.02 t / (24hm ² ) is 2.8 times higher than the reference setting, but is relatively low compared to the previously mentioned cases. The problem is in the existence of a layer of trunk on the surface that does not allow the desired spiral flow to develop fully. However, the furnace operates in both cases in an uneconomical manner in terms of energy consumption.

In the majority of cases mentioned in the examples, extremely high dissolution rates of the designed space were achieved. However, the results cannot be automatically applied to the entire melting process. It is a realization of only one melting process, the dissolution of sand grains, in a situation where the melting space has no reserve. The performance of such a special melting chamber can then be further reduced, but not substantially [31], considering the refining process as a further process. Most significantly, however, the performance of the melting chamber can be reduced if the batch is also converted into glass in the same chamber, as is evident from the results in Example 4. Indeed, once the melting performance limitations have been removed by optimized glass flow, it becomes a control event. of the entire melting process, precisely the batch conversion and the entire dissolution capacity of the space will not be utilized unless the batch conversion rate is increased. Nevertheless, specific melting capacities higher or significantly higher than 10 t / m ³ 24h can be expected. Major efforts should then be made to increase the conversion capacity of the batch to glass.

-23 GB 304703 B6

Literature

1. Danckwerts, P.V .: Chem. Eng.Sci. 2, 1 (1953).

2. Cooper, A. R., J. Am. Ceram. Soc. 42, 93 (1959).

3. Smrček, J .: Glassmaker and Ker. 23, 270, 304 (1973).

4. Cooper, A. R., J. Am. Ceram. Soc. 43, 97 (1960).

5. Moult, A .: Glass Technol. 23 (2): 106-112 (1982).

6. Mase, H., Oda, K .: J. Non-Cryst. Solids 38, 39, 807-812 (1980).

7. Layens, G .: Glastechn. Ber. 47, (11), 251-270 (1974).

8. Carling, J .: Glastechn. Ber. 49, (12), 269-277 (1976).

9. Patankar, S.V .: Numerical Heat Transfer and Fluid Flow, Hemisphere Publishing Co. McGraw-Hill 1980.

10. Ungan, A., Viskanta, R., Glastechn. Ber. 60, (4), 115-124 (1987).

11. Mumame, R. A., Moreland, N.J .: Ceram. Eng. Sci. Why. 9 (3-4), 192-202 (1988).

12. Simonis F. De Waal, H. and Beerkens, R.C.G., XIV Int. Congr. on Glass - Collected Papers Part III (1986), pp. 118-127.

13. Ungan, A. Viskanta, R.: Glastech. Ber. 60, 71 (1987).

14. Ungan, A., Viskanta, R., Glass Technol. 28 (6): 252-260 (1987).

15. Choudhary, M.K .: J. Non-Cryst. Solids 101, 41-53 (1988)

16. Viskanta, R .; J. Non-Cryst. Solids 177, 347-362 (1994).

17. Goldberg, A.J .: Glastechn. Ber. 46 (4), 67-70 (1973).

18. Simonis F., Proceedings of the 2nd Int. Conf. Advances in Glass Fusion and Processing, Glastech. Ber. 63K, 1 (1990).

19. Ungan, A., Turner, W. H., Viskanta, R., Glastech. Ber. 56K, 125 (1983).

20. Nemec L., Miihlbauer M .: Glastechn. Ber. 56K, 82 (1983).

21. Beerkens, R., Muijsenberg, H., van den Heiden, T .: Glastechn. Ber. Glass Sci. Technol., 67 (1), 179 (1994).

22. Ungan, A: Glastechn. Ber. 63K, 19-28 (1990).

23. Matyas, I, Nemec, L .: Glass Sci. Teechnol. 76 (2), 71-80 (2003).

24. Oda, K, Kaminoyama, M .: J. Cer. Soc. Japan 117 (6), 736-741 (2009).

25. Kasa, S., Lisy, A., Novotny, F .: PV 2011-651 (2011).

26. Cooper, A.R .: Collected Papers of the XIV International Congress on Glass (1986), pp.1-8.

27. Consortium on the development of innovative glass melting BRIG 2020: The International Conference of Glass Experts, Brig, March 26-29 (Switzerland).

28. Nemec, L., Jebava, M .: Eur. J. Glass Sci. Technol. A, 47 (3), 68-77 (2006).

29. Nemec, L., Jebava, M., Cincibus, P .: Ceramics-Silicates, 50 (3), 140-152 (2006).

30. Nemec, L., Cincibus, P .: Ceramics-Silicates, 52 (4), 240-249 (2008).

31. Nemec, L., Cincibus, P .: Ceramics-Silicates, 53 (3), 145-155 (2009).

32. Polak, M., Nemec, L., Ceramics-Silicates, 54 (3), 212-218 (2010).

33. Polak, M., Nemec, L .: Journal of Non-Cry became the line Solids 357 (16-17), 3108-3116 (2011).

34. Polak, M., Nemec, L .: Journal of Non-Crystalline Solids 358 (2012).

35. Cincibus, P., Nemec, L .: Accepted in: Eur. J. Glass Sci. Technol. A, 53 (2012).

36. Polák, M .: Unpublished Results.

-24GB 304703 B6

PATENT CLAIMS

Claims (12)

A glass melting furnace for the continuous melting of glass by controlled glass convection, in which a molten glass comprising insoluble particles, in particular glass sand, is present in a horizontally oriented flow and separate melting space by means of energy sources; the melting chamber comprises a bottom (1), a foundation wall (2) and a rear flow wall (3) and opposed side walls (4), a vault (5), and a transverse dam wall (8) submerged in the glass (6), characterized in that the energy sources are arranged in the melting chamber in at least one row in the longitudinal axis of the melting chamber or parallel to this longitudinal axis, between the loading wall (2) and the transverse dam wall (7) in the glass (6) or transverse a series (9) of energy sources in the melting portion of the glass (6) to induce a spiral flow of the glass (6) with a circular movement across the melting portion. Glass melting furnace according to claim 1, characterized in that the energy sources are arranged in one or both side walls (4). Glass melting furnace according to claim 1 or 2, characterized in that the energy sources are arranged at regular intervals from one another. Glass melting furnace according to claims 1 to 3, characterized in that the energy sources are heating electrodes (10) and / or industrial glass burners (11). Glass melting furnace according to one of the preceding claims 1 to 4, characterized in that the melting portion is terminated by a transverse row (9) of heating electrodes (10) installed in the bottom (1). 11 drawings List of reference marks: 1 bottom 2 foundation wall 3 rear flow wall 4 side walls 5 vault 6 enamel 7 transverse dam wall 9 transverse row 9 power sources 10 heating electrodes Industrial burners 12 input 13 output -25GB 304703 B6 Giant. 1a - State of the art Fig.2 -26GB 304703 B6 Fig.4 -27CL 304703 B6 Giant. 5 -28GB 304703 B6 Lt) -29GB 304703 B6 Giant. 9 -30GB 304703 B6 -31 GB 304703 B6 -32GB 304703 B6 -33GB 304703 B6