HK1148514A - Stirring system and method for homogenizing glass melts - Google Patents

Description

Stirring system and method for homogenizing glass melt

Technical Field

The present invention relates to a stirring system for molten glass, to a corresponding stirring vessel and stirrer, and to a method for assembling these components and for stirring molten glass. The invention relates in particular to the structural design of the stirring system, the stirring element, the stirrer and the stirring vessel for the glass melt, which are made to match one another in their mode of operation (that is to say homogenization of the glass melt).

Background

Structural parts consisting of precious metals and precious metal alloys, such as preferably PGM (PGM equals platinum group metal), are used in the glass industry, in particular in apparatuses for melting and hot forming special glasses. These pieces of equipment used in the fusion technology, also known as PGM products, serve to melt, purify, transport, homogenize and distribute liquid glass.

Such structural components are essentially structures composed of solid PGM materials or of high-temperature-resistant materials (ceramic heat-resistant materials, metallic special materials) with a thin-walled protective PGM coating, for example in the form of a thin-sheet metal or PGM surface coating (applied, for example, by plasma spraying or flame spraying).

The equipment components carrying the glass melt are usually noble metal sheet structures designed as thin-walled tube systems. Molten glass flows through these pipe systems at temperatures between 1000 ℃ and 1700 ℃.

Because of their high melting point, PGM materials are distinguished by high temperature resistance and also by their high mechanical strength and wear resistance and are therefore particularly suitable for producing structural parts in the equipment or equipment parts which are to be brought into contact with the glass melt. Suitable materials are platinum and platinum alloys and/or other platinum group metals, optionally also containing minor amounts of base metals as further alloyed components or as oxidation additives. Typically, the materials are purified platinum, platinum rhodium alloys and platinum iridium alloys containing small amounts of finely distributed refractory metal oxides, such as in particular zirconium dioxide or yttrium oxide, to improve strength and resistance to high temperature creep.

The glass melting process is broken down into the following stages: melting, refining, conditioning, feeding and forming. To increase the degree of glass homogenization, a stirrer was used. Agitation is part of the conditioning and therefore occurs after purification and before feeding. The change in glass viscosity with temperature is critical to all glass technologies. In order to achieve homogeneous melting, it is necessary to obtain a dynamic viscosity at this temperature of eta-10²Temperature of dPa · s. By way of comparison, at 20 ℃ water has a viscosity of 0.01 dPas, olive oilHas a thickness of about 10²dPa.s viscosity and honey has a viscosity of about 10⁴Viscosity of dPa · s. Heat treatment, i.e. the feeding and shaping of the glass, is carried out according to the specific treatment at 10³To 10⁸dPa.s. As a result, the viscosity of the glass during stirring was at 10²To 10⁴dPa · s. The borosilicate glass has a dynamic viscosity of, for example, η 10 at-1450 deg.C³dPa·s。

As the temperature and dynamic viscosity show in the above data, effective glass stirring presents technical challenges.

Agitation is one of the most important basic process engineering operations. In its simple mode, two or more parts are associated with each other and are distributed inside each other by introducing a flow action by means of a stirring tool, in order to obtain a uniform composition in the volume of the smallest possible unit.

The following four mixing tasks can be defined: homogenization, suspension, dispersion and heat transfer.

Heat transfer, i.e. heat exchange between the material being mixed and the surrounding medium, may occur through the walls of the mixer, but heat transfer is of secondary importance in the design of stirring systems for glass.

Since, in the case of glass, the main and additional phases are liquid, the stirring task is only for homogenization. Homogenization is the mixing of solids or liquids that are soluble in each other while equalizing concentration differences and/or temperature differences.

Sequential mixing refers theoretically to the delivery of the components of the materials being mixed. In this case, it is possible to distinguish 5 independent basic operations, which in some circumstances may trigger one another.

Distribution and mixing: distribution, blending, particle interchange on an ordered matrix and random matrix basis. From a physical point of view, gravity and coulomb friction must be overcome.

Dispersing and mixing: breaking up aggregates and agglomerates. In this case, the resistance caused by the adhesive stress must be overcome.

Layer mixing: stretching, squeezing, folding and overcoming newtonian friction.

Disturbance mixing: turbulent flow(s) are established in the liquid and gas.

Diffusion and mixing: concentration equalization by diffusion. For example: a stationary fluid.

In the case of mixing highly viscous glass, this can lead to mixing involving layers and distribution, which is very close to kneading.

Kneading means mixing of a slurry-like substance of high viscosity. The energy input involved is many times higher than when mixing substances of low viscosity. The lack of turbulence can be proposed as a feature of the intensity of the mixing operation if the working process of "kneading" is considered from the viewpoint of the flow behaviour. Mass transfer occurs by shearing, mechanical separation and extrusion.

A difficulty in handling high viscosity liquids is the laminar flow behaviour. For any mixing process, this behavior means that there is a problem with the exchange of the respective stream filaments and components to be mixed. In the case of laminar flow, forces caused by viscosity (shear stress, shear) dominate.

In order to achieve a defined mixing result, it is a prerequisite that laminar flow affects the entire vessel volume.

In the case of high viscosities, which are common for glass, only forced dosing ensures a sufficient quality of homogenization.

In the prior art of the glass industry, the plant components, i.e. the stirrer, are responsible for the homogenization of the glass melt in the crucible or in the stirring section or in the stirring chamber. The mixing vessel will always have a cylindrical or slightly conical shape with "smooth" walls. In a continuous melting process, glass is fed into the stirring vessel from the top or bottom in a lateral direction through an inlet pipe. The glass then leaves laterally at a different height from the inlet, by means of an outlet pipe or through the bottom of the container. The difference in height between the inlet and the outlet makes it possible to distribute the positive feed effect of the stirring element during the continuous glass melting process, since the entire volume of glass has to pass through the stirring vessel. As a result, the stirring task is one of layer mixing and distributive mixing that affects the entire vessel volume.

DE102004034798 a1 relates to a stirring system for glass melts. In this reference, a stirrer is provided having a shaft and at least two sets of paddles, wherein the shaft defines a longitudinal axis. The paddles each include a paddle and at least one opening, the paddles aligned parallel to the longitudinal axis. At least two sets of paddles are positioned on the shaft at a distance from each other. At least one set of baffles is also provided, positioned between the sets of paddles.

Disclosure of Invention

It is an object of the present invention to provide an improved or alternative stirring vessel for molten glass, a corresponding stirring system and methods of assembling these components and for stirring molten glass.

This object is achieved by the subject matter of the claims.

The invention relates in particular to a mixing system with a mixer and a mixing container. The geometry of the stirrer and the vessel are made to match each other and thus in their mode of operation in order to achieve an optimal stirring result. The wall of the cylindrical or slightly conical mixing vessel has a plurality of baffles in the form of attached or integral structures, which are designed as two-dimensional or three-dimensional elements, it being possible for the three-dimensional elements to be designed to form part of the wall of the mixing vessel. This results in the following advantages: the surface area of the container increases, which results in improved shearing of the glass. In addition, the liquid is directed by the baffles towards the middle of the vessel or better fed to the stirrer. This ensures that the stirrer acts on the entire volume of glass.

The stirring vessel for molten glass according to the present invention has a longitudinal axis. In this case, the stirring vessel may have a linear and/or curved shape. The stirring vessel has an inner circumferential surface that may take on different shapes, among other surfaces. The inner surface may be formed from one or more metals. The inner circumferential surface has at least two or more baffles extending away from the inner circumferential surface of the stirred vessel or the wall of the stirred vessel into the deeper interior of the stirred vessel. The baffles are arranged at different positions along the longitudinal axis or at different heights of the stirred vessel or about the longitudinal axis at an angle offset from the longitudinal axis.

The baffles may be offset relative to each other at one and/or adjacent positions of the longitudinal axis by an angle of 60 °, 90 °, 120 ° or 180 ° about the longitudinal axis. Irregular spacing is also possible.

A plurality of baffles may be provided, attached respectively to at least two groups of at least two baffles in each group at respective positions along the longitudinal axis, the baffles of adjacent groups being arranged offset with respect to each other.

Another alternative or additional aspect of the invention relates to a stirring vessel for molten glass having a longitudinal axis and an inner circumferential surface with at least one baffle extending from the inner circumferential surface into the interior of the stirring vessel. In this case, the baffle has a profile (when considered transverse to the longitudinal axis) that narrows or tapers, at least in part, substantially away from the inner circumferential surface of the stirred vessel.

The contour of the baffle may at least substantially or completely narrow from the inner circumferential surface to the interior of the stirred vessel.

In the case of a further aspect of the invention, at least two, and preferably three baffles may be provided at various locations along the longitudinal axis.

The inner circumferential surface is substantially continuous and is circular, elliptical or oval in cross-section.

The inner circumferential surface of the stirring vessel may be formed by at least one surrounding metal sheet and the baffle(s) is/are fixedly arranged on the surrounding metal sheet. They may be machined at least partially from the surrounding sheet metal. The baffle can be formed from at least one further metal sheet which is arranged fixedly on the surrounding metal sheet, preferably by welding or soldering.

The baffles may extend the central portion furthest into the interior of the mixing vessel and at least one, and preferably both, of the side portions somewhat closer together.

The baffles may also be formed from one or more metal sheets, the outer edge(s) of which are at least partially adapted to the inner circumferential surface of the agitation vessel and are at least partially connected thereto, and preferably have at least one transition or join line.

The baffle has at least a first face and a second face, the first face having a first orientation and the second face having a second orientation different from the first orientation.

The first and second faces may also be inclined relative to each other at an angle of about 30 ° to 120 °, preferably about 45 ° to 105 °, more preferably about 60 °.

The stirred vessel according to the invention may be at least partially (preferably completely) made of an oxide dispersion-hardened PGM material, which is particularly suitable for molten glass for optical applications. The material is particularly resistant to corrosion, especially in the region where the stirring vessel contacts the molten glass.

The baffles may have apertures to reduce weight or provide further compression to the molten glass.

Another additional or alternative aspect of the invention relates to a stirrer for molten glass, which may correspond to the stirring vessel described above. The stirrer likewise has a longitudinal axis which, in the assembled state, can coincide with the longitudinal axis of the stirred vessel. A shaft is also provided having at least one stirring element extending radially away from the shaft. Furthermore, the stirring element has a profile or envelope (especially if it rotates) that narrows away from the axis, substantially transverse to the longitudinal axis at least partially or substantially completely or practically completely.

The stirrer has a plurality of stirring elements which, in respective positions along the longitudinal axis, can be arranged in at least two groups of at least two stirring elements, respectively, the stirring elements of adjacent groups being arranged offset with respect to each other.

Yet another additional or alternative aspect of the present invention is directed to a stirring system for molten glass having a stirring vessel or stirrer as described above or claimed below. In this case, at least one stirrer is provided with a shaft and at least one stirring element. In this case, the stirring element is formed such that: the agitator can be introduced into the stirred vessel by at least one axial or translational relative movement of the agitator with respect to the stirred vessel, at least one subsequent or synchronous relative rotation of the agitator with respect to the stirred vessel, and further axial or translational relative movement of the agitator with respect to the stirred vessel. In this case, the agitator in the operating state can be rotated in the agitation vessel.

The stirring element(s) may be formed such that it or they correspond to the contour of the baffles during rotation in the operating state. Further, the stirring element(s) may have a profile or envelope that narrows with distance from the axis.

The stirring system may be at least partially (preferably completely) made of oxidatively dispersion hardening PGM material.

The stirrer or stirring element may have a gap to reduce weight or provide further compression of the molten glass.

In addition, the present invention relates to a method of manufacturing a stirring vessel for molten glass having a longitudinal axis. The method specifically comprises the following steps: forming an inner circumferential surface; the inner circumferential surface is formed with at least two baffles such that the baffles extend from the inner circumferential surface into the interior of the stirred vessel; and arranging the baffles at different positions relative to the longitudinal axis and offset by an angle about the longitudinal axis.

The present invention additionally or alternatively relates to a method of manufacturing a stirring vessel for molten glass having a longitudinal axis, comprising the steps of: forming an inner circumferential surface; the formed inner circumferential surface has at least one baffle extending from the inner circumferential surface into the interior of the stirred vessel; and forming or arranging the baffle plate to have a profile that narrows at least partially from the inner circumferential surface to an interior of the stirred vessel substantially transverse to the longitudinal axis.

The present invention also relates to a method of assembling a stirring system for molten glass according to a corresponding embodiment or at least one of the above aspects, the method comprising the steps of: the stirrer is introduced into the stirred vessel by at least one axial or translational relative movement of the stirrer with respect to the stirred vessel, by a further subsequent or synchronous movement of the stirrer with respect to the stirred vessel by relative rotation and by a further axial or translational relative movement of the stirrer with respect to the stirred vessel.

Furthermore, the present invention relates to a method of stirring molten glass with a stirring system according to a respective embodiment or at least one of the above aspects, the steps of the method being as follows: supplying molten glass through an inlet of the stirring vessel; rotating a stirrer in a stirring vessel and passing molten glass through the interior of the stirring vessel; the molten glass is guided by the stirring element and the baffle plate through the compression formed therebetween, and the molten glass is crushed, kneaded, and/or extruded during rotation of the stirrer and passage of the molten glass through the interior of the stirring vessel, and then the molten glass is discharged through the outlet of the stirring vessel.

Drawings

The drawings are intended to illustrate by way of example preferred embodiments in accordance with the invention. In the drawings:

fig. 1A shows a schematic view of a stirring system according to the invention from above in the direction of the longitudinal axis, with an embodiment of a stirring vessel according to the invention with a stirrer corresponding thereto.

FIG. 1B shows a schematic cross-sectional view along A-A according to FIG. 1A;

FIG. 1C shows a schematic view of a baffle according to the invention (including itself only, without a stirred vessel);

FIG. 1D shows a perspective view of a blender according to the present invention;

FIG. 1E illustrates the interaction between the agitator shown in FIG. 1D and the baffles shown in FIG. 1C;

FIG. 2A shows a schematic view of another mixing system according to the invention in the direction of the longitudinal axis, with another embodiment of a mixing vessel according to the invention with a corresponding mixer;

FIG. 2B shows a schematic cross-sectional view taken along B-B according to FIG. 2A;

FIG. 2C shows a schematic view of another baffle according to the invention (including itself only, without the agitation vessel);

FIG. 2D shows a perspective view of another agitator according to the present invention;

FIG. 2E illustrates the interaction between the agitator shown in FIG. 2D and the baffles shown in FIG. 2C;

FIG. 3A shows a schematic view of yet another mixing system according to the present invention, along the longitudinal axis, with yet another embodiment of a mixing vessel according to the present invention with a corresponding mixer;

FIG. 3B shows a cross-sectional schematic view taken along C-C according to FIG. 3A;

FIG. 3C shows a schematic view of further baffles (including itself only, without the agitation vessel) according to the present invention;

FIG. 3D shows a perspective view of yet another agitator according to the present invention;

FIG. 3E illustrates the interaction between the agitator shown in FIG. 3D and the baffles shown in FIG. 3C;

FIG. 4A shows a schematic view of yet another mixing system according to the present invention in the direction of the longitudinal axis, with yet another embodiment of a mixing vessel according to the present invention with its corresponding mixer attached;

FIG. 4B shows a schematic cross-sectional view taken along D-D according to FIG. 4A;

FIG. 4C shows a schematic view of yet another baffle according to the present invention (including itself only, without the agitation vessel);

FIG. 4D shows a perspective view of yet another agitator according to the present invention;

FIG. 4E illustrates the interaction between the agitator shown in FIG. 4D and the baffles shown in FIG. 4C;

FIG. 5A shows a schematic view of yet another mixing system according to the present invention in the direction of the longitudinal axis, with yet another embodiment of a mixing vessel according to the present invention with its corresponding mixer attached;

FIG. 5B shows a schematic cross-sectional view taken along E-E according to FIG. 5A;

FIG. 5C shows a schematic view of yet another baffle according to the present invention (including itself only, without the agitation vessel);

FIG. 5D shows a perspective view of yet another agitator according to the present invention;

FIG. 5E illustrates the interaction between the agitator shown in FIG. 5D and the baffles shown in FIG. 5C;

FIG. 6A shows a schematic view of yet another mixing system according to the present invention in the direction of the longitudinal axis, with yet another embodiment of a mixing vessel according to the present invention with its corresponding mixer attached;

FIG. 6B shows a cross-sectional schematic view taken along F-F according to FIG. 6A;

FIG. 6C shows a schematic view of yet another baffle according to the present invention (including itself only, without the agitation vessel);

FIG. 6D shows a perspective view of yet another agitator according to the present invention;

FIG. 6E illustrates the interaction between the agitator shown in FIG. 6D and the baffles shown in FIG. 6C.

Detailed Description

Fig. 1A shows a stirrer 3 having a shaft 30, which stirrer 3 is rotatably arranged within the stirred vessel of the purification chamber. In this figure, the stirring elements 4 can be seen in particular offset with respect to each other along the longitudinal axis. In the illustrated embodiment, the stirring elements 4 are offset by 90 ° with respect to one another. The baffle 2 extending inwardly from the inner wall 10 of the mixing vessel can also be seen in this plan view. These baffles may project completely or partially into the interspace left by the stirring element 4.

This function is more clearly shown in fig. 1B. Fig. 1B shows that the baffle 2 can be seen in this figure as tapering or narrowing towards the interior of the stirred vessel 1. The baffle plate 2 is attached to the inner circumferential surface of the stirring vessel 1 in such a manner that the baffle plate occupies and makes smaller the empty space between the individual stirring elements 4 of the stirrer.

In this case, however, only the baffle 2, which extends substantially perpendicular to the plane of the paper in fig. 1B, can be seen. Of the other baffles, only those located at the rear are shown. The stirring element 4 is able to rotate freely during operation and thus take advantage of more of the clearance left by the baffles 2. In fig. 1A and 1B, it can be seen that: how the glass melt is kneaded, sheared and otherwise processed by the stirring element 4 of the stirrer during rotation of the stirrer 3, although the glass melt can travel from the inlet 11 to the outlet 12.

The baffles comprise planar inclined metal sheets attached tangentially at a distance from the side surface of the truncated cone (inner wall of the stirring vessel). In the space of each stirring element, two baffles are mirror-inverted with respect to each other. The baffles are radially offset at an angle along the central axis 30.

Apart from the illustrated concentric arrangement of the stirrer 3 relative to the stirred vessel 1, a non-concentric arrangement can likewise be achieved by means of a suitable configuration of the stirring elements 4 and the baffles 2.

Fig. 1C shows a perspective view of how the baffle 2 can be formed. A first wall 20 and a second wall 21 may be provided and the first wall 20 and the second wall 21 may have a linear transition 22. Towards the inner wall 10 (not shown) of the mixing container, corresponding outer sides 23 are provided, which completely face the inner wall 10 or are connected thereto. Gaps (not shown) between the inner wall and the outer side are also conceivable.

The stirrer 3 is shown in perspective in fig. 1D. On the shaft 30 there are stirring elements 4, said stirring elements 4 being spaced apart along the longitudinal axis (not shown) of the stirrer 3. Each stirring element 4 attached to the stirring axle or axle 30 takes the form of two truncated cones 42, 43, which truncated cones 42, 43 are turned upside down one above the other and have two mutually parallel, planar first and second faces or metal sheets 40, 41. The plane is bounded by hyperbolic edges consisting of axially parallel conical sections. The position of the plane is radially offset in an angular manner from one stirring element to the other. This form may alternatively be described as: in the embodiment shown, the stirring element 4 has a first face 40, substantially planar, and a corresponding second face 41, the second face of said first face each having a rhomboid shape, with relatively flat included angles being rounded. The first face 40 and the second face 41 extend substantially parallel to the longitudinal axis of the stirrer 3, and the first face 40 and the respective second face 41 are in each case opposite one another at the same distance from the longitudinal axis. The stirring element 4 is enclosed by a third face 42 and a fourth face 43, respectively. In the embodiment shown, it is clear how the stirring element narrows outwards over the entire length, while the third face 42 and the fourth face 43 transition into each other in a line. This line may be a straight line or a curved line. In the illustrated embodiment, this line is slightly curved, so that it does not much look like a straight line but rather a circle or substantially a circle during rotation of the agitator. The lowermost stirring element 4 in fig. 1D has a top corner (light point)44 in the downward direction, said top corner being essentially formed by the corresponding shape of the fourth face 43.

Fig. 1E shows the interaction of the stirring element 4 and the baffle 2, the inner wall not being shown for reasons of simplicity. It can be seen how closely the stirring element 4 fits into the contour formed by the baffles during rotation of the stirrer.

Due to the large volume of the stirring elements 4 and baffles 2, the molten glass is frequently guided through compression as it flows through the stirring vessel. The relative motion between the stirring element and the baffle kneads the glass melt. The radially angularly offset arrangement of the stirring elements and baffles has the following effect: the glass flow is doubly crushed by the stirring element at each layer.

The radial angular offset of the stirring elements makes it possible to first lower the stirrer into the stirring vessel, which can also be replaced by lowering the height of the stirring elements and then rotating it by an offset angle.

Fig. 2A shows a modified stirring element 104, which is formed by a substantially horizontally arranged metal sheet and a substantially vertically arranged face. This is a material saving variant that allows greater savings in the materials used, among other reasons. In particular in fig. 2A, it is more clear how the horizontal metal sheets can be angularly offset. The second metal sheet, which is arranged substantially vertically and forms the stirring element together with the substantially horizontal metal sheet, is shaped such that when the shown stirrer is inserted into the stirring vessel, said substantially vertical metal sheet fits between the horizontal faces of the baffles when moving in a translatory manner.

Fig. 2B shows the interaction of the respective baffles 102 and stirring elements 104 in the installed state. During assembly, it is also clear how, due to the offset arrangement of the baffles and the stirring elements, the lowermost stirring element must be moved in translation between the uppermost baffles in order to be subsequently turned, here by 90 °, and between two baffles in translation, etc. The stirring elements arranged further above are correspondingly moved through the baffles.

Fig. 2C illustrates the shape of the baffle 102 and the components that are partially assembled together and/or joined together by various components and that transition from one to the other along line 122, according to the present embodiment. The conical contour formed by the baffle from the outside inwards can be seen here. The baffle plate 102 is attached to an inner circumferential surface (not shown) of the agitation vessel in such a manner as to occupy and make smaller the vacant space between the respective agitation blades of the agitator. The baffles 102 may be constructed in a similar manner to a stirrer from horizontal and through-center intersecting planar vertical metal sheets 120, 121. The horizontal metal sheet has a profile that fills the empty space of the stirring blade. At each stirring blade gap, two baffles are mirror-inverted with respect to each other. Along the central axis, the baffles are radially offset in an angular manner.

Fig. 2D shows the shaft 30 with the respective stirring element 104, which is formed from metal sheets 140 and 141. Each stirring element 104 attached to the stirring shaft comprises a dumbbell-shaped planar horizontal metal sheet 141 and a vertical triangular metal sheet 140. The vertical triangular metal sheets 140 cross the dumbbell-shaped horizontal metal sheets 141 from the center and their bases are against the shaft 30 so that their tips are on the outermost periphery of the stirrer. The positions of the stirring elements 104 are radially offset relative to each other in an angular manner.

Fig. 2E illustrates the interaction of the stirring element 104 and the baffle 102. The triangular vertical metal sheets 140 of the stirring element 104 move the glass melt radially. Compression is regularly formed between the vertical metal sheets 140 of the stirrer and the baffles 102 of the stirring vessel during rotation each time they pass each other. These compressions compress the glass melt. The horizontal metal sheets fitted into the stirrer blades and baffles continuously shut off the glass flow.

According to fig. 3A, the three stirring elements 204 are offset by 120 ° with respect to one another. Baffles 202 are formed accordingly to assemble the agitator and the agitation vessel as described above.

In fig. 3B, the conical shape of the stirring element 204 and the baffle 202 can be seen.

The corresponding configuration of baffles 202 and stirring elements 204 is illustrated in fig. 3C and 3D. These baffles and stirring elements are constructed from metal sheets 220, 221 and 240, 241, respectively, which are arranged substantially transversely with respect to each other. Baffles 202 are attached to the inner circumferential surface (not shown) of the mixing vessel in a manner that occupies and makes smaller the empty space between the individual mixer blades of the mixer. Baffles 202 are constructed from horizontal and substantially intersecting planar vertical metal sheets 220, 221 in a similar manner to that making up the agitator. The horizontal metal sheet 220 has a profile that fills the empty space of the stirring blade. Along the central axis, the baffles are radially offset in an angular manner.

Each stirring element 204 attached to the stirring shaft or shaft 30 comprises a star-shaped, planar horizontal metal sheet 241 and a vertical triangular metal sheet 240. The vertical triangular metal sheets 240 are located on each vertex of the star shape of the horizontal metal sheets 241 and intersect them through the center. The bottom edges of the vertical metal sheets 240 abut the agitator shaft 30 so their apexes are at the outermost periphery of the agitator. The positions of the agitator blades are radially offset in an angular manner relative to each other. It is here clear from the stirring element that the metal sheet 241 may have a substantially rectangular shape.

This function can be seen in fig. 3E and is substantially the same as described above.

More complex structures that may have stiffness advantages are shown in fig. 4A through 4E. According to fig. 4A, the stirring elements 304 can be guided through between the baffles 302 during the assembly process in the manner already described above.

In fig. 4C and 4D, the structure of these elements is shown. A relatively simple baffle 302 configuration is shown in fig. 4C: the two metal sheets 320 and 321 meet at a joining line 322, while fig. 4D shows a stirring element 304 assembled from a relatively large number of metal sheets 340 to 343. The stirring elements are attached to the stirring shaft or shaft 30 and have two pyramidal shapes, one inverted on the other. The stirring elements are radially offset relative to each other in an angular manner. The baffle 302 comprises a planar, inclined metal sheet attached tangentially at a distance from the edge of the pyramidal shape of the stirring element. Along the central axis, the baffles are radially offset in an angular manner.

It is clear that, according to the invention, there may be a large number of different forms of individual elements and methods of joining them to each other. Fig. 4E shows the interaction of the elements. Baffles 302 are attached to the inner circumferential surface (not shown) of the mixing container in such a way as to occupy and make smaller the empty space between the individual mixing elements 304 of the mixer. Because of the large volume of the stirring elements and baffles, the molten glass is frequently directed through compression as it flows through the stirring vessel. The relative motion between the two stirring elements in these compressions kneads the glass melt. The radially angularly offset arrangement of the stirring elements and baffles has the following effect: the glass flow is doubly crushed by the stirring element at each layer.

The radial angular offset of the stirring elements makes it possible to first lower the stirrer into the stirring vessel, which can also be replaced by lowering the height of the stirring elements and then rotating it by an offset angle.

Fig. 5A to 5E show a further embodiment of the invention, in particular an arrangement with baffles 402 arranged offset and associated stirring elements 404. In the case of the baffles 402 shown in this embodiment, it is clear that they can be connected in pairs or all to each other. This increases the stability of the stirred vessel (not shown). Baffles 402 are attached to the inner circumferential surface (not shown) of the mixing container in such a way as to occupy and make smaller the empty space between the individual mixing elements 304 of the mixer. According to fig. 5C, the baffle comprises planar, vertical and horizontal metal sheets 420, 421 attached to the inner circumferential surface of the mixing container in such a way that they leave only openings in the form of triangular prisms 422.

The stirring elements 404 (or stirring blades) have a horizontal cross-sectional area that is similar in shape but smaller than the triangular space 422 left open by the baffles. Each stirring element is formed by two opposite horizontal triangular metal sheets 441 and is closed at their periphery by three vertical jacket sheets 440.

The baffles are radially offset in an angular manner along the central axis of the stirred vessel. Because of the large volume of the stirring elements and baffles, the molten glass is frequently directed through compression as it flows through the stirring vessel. The relative motion between the two stirring elements in these compressions kneads the glass melt. The radially angularly offset arrangement of the stirring elements and baffles has the following effect: the glass flow is doubly crushed by the stirring element at each layer.

The radial angular offset of the stirring elements makes it possible to first lower the stirrer into the stirring vessel, which can also be replaced by lowering the height of the stirring elements and then rotating it by an offset angle.

Fig. 6A to 6E show an embodiment with baffles 502 and stirring elements 504, which are likewise assembled from a plurality of metal sheets 520 and 523 and 540 and 541 and which cooperate as shown in fig. 6E.

Each prismatic stirring element 504 attached to the stirring shaft 30 has a star-shaped base area, compare fig. 6D. The bottom area is orthogonal to the axis of the stirring shaft. The stirring elements are radially offset in an angular manner with respect to each other.

According to fig. 6C and 6E, baffles 502 are attached to the inner circumferential surface (not shown) of the stirring vessel in such a way as to occupy and make smaller the empty space between the individual stirring elements of the stirrer. The baffles comprise planar, vertical and horizontal metal sheets 522, 523 and 520, 521 attached to the inner circumferential surface of the mixing container in such a way that they leave only an opening in the form of a star. Along the central axis, the baffles are radially offset in an angular manner.

Because of the large volume of the stirring elements 504 and baffles 502, the molten glass is frequently directed through compression as it flows through the stirring vessel. The relative motion between the two stirring elements in these compressions kneads the glass melt. The radially angularly offset arrangement of the stirring elements and baffles has the following effect: the glass flow is doubly crushed by the stirring element at each layer. The radial angular offset of the stirring elements makes it possible to first lower the stirrer into the stirring vessel, which can also be replaced by lowering the height of the stirring elements and then rotating it by an offset angle.

The invention also includes the features illustrated in the drawings, even if they are not shown in combination with other features and/or not mentioned above or below.

The invention likewise comprises embodiments having any combination of features which are mentioned or shown above or below with respect to different embodiments.

The invention also includes the precise or precise expression, characteristic, value or range, etc., even if such expression, characteristic, value or range is referred to above or below, for example, in combination with an expression such as "substantially, about, left-right, substantially, generally, at least," etc. (i.e., "substantially 3" is also intended to include the meaning of "3" or "substantially radially" is also intended to include "radially"). Moreover, the expression "respectively" means "and/or".

Claims (18)

1. A stirring system for molten glass having a stirring vessel (1) and a stirrer (3), wherein the stirring system comprises:

a. at least one stirrer (3) having a shaft (30) and at least one stirring element (4),

b. the stirring element (4) is formed such that the stirrer (3) can be introduced into the stirring vessel (1) by at least one axial and/or translational relative movement of the stirrer (3) with respect to the stirring vessel (1), at least one subsequent or synchronous relative rotation of the stirrer (3) with respect to the stirring vessel (1) and a further axial and/or translational relative movement of the stirrer (3) with respect to the stirring vessel (1),

c. wherein the stirrer (3) is rotatable in the stirred vessel (1) in the operational state, and the stirred vessel (1) comprises:

d. a longitudinal axis (49), and

e. an inner circumferential surface (10),

f. the inner circumferential surface (10) has at least two baffles (2), the baffles (2) extending from the inner circumferential surface (10) or a wall of the inner circumferential surface into the interior of the stirred vessel (1),

g. the baffle (2) also has a profile that narrows at least partially substantially transversely to the longitudinal axis (49), away from the inner circumferential surface (10) of the stirring vessel (1).

2. The stirring system as claimed in claim 1, wherein the baffles (2) are offset relative to one another about the longitudinal axis (49) by an angle of 60 °, 90 °, 120 ° or 180 °.

3. Stirring system according to claim 2, wherein a plurality of baffles (2) are provided, at respective positions along the longitudinal axis attached in at least two groups of at least two baffles (2) each, the baffles (2) of adjacent groups being arranged offset with respect to each other.

4. Stirring system according to claim 3, wherein at least two, preferably three baffles (2) are provided at each position along the longitudinal axis (49).

5. Stirring system according to claim 4, wherein the inner circumferential surface (10) is substantially continuous and circular in cross-section.

6. Stirring system according to claim 5, wherein the inner circumferential surface (10) of the stirring vessel (1) is formed by at least one surrounding sheet metal and the baffle (2) is fixedly arranged on the surrounding sheet metal.

7. Stirring system according to claim 6, wherein the baffle (2) is formed by at least one further metal sheet, which is fixedly arranged on the surrounding metal sheet, preferably by welding or soldering.

8. Stirring system according to claim 7, wherein the central part of the baffle (2) extends furthest into the interior of the stirring vessel (1) and at least one, preferably both side parts extend somewhat closer.

9. Stirring system according to claim 8, wherein the baffle (2) is formed by one or more metal sheets (20, 21) whose outer edge (23) fits at least partially into the inner circumferential surface (10) of the stirring vessel and is at least partially connected with the inner circumferential surface (10) of the stirring vessel, and preferably has at least one transition or joining line (22).

10. Stirring system according to claim 9, wherein the baffle (2) has at least one first face (20) having a first orientation and a second face (21) having a second orientation different from the first orientation.

11. Stirring system according to claim 10, wherein the first face (20) and the second face (21) are inclined with respect to each other by an angle of about 30 ° to 120 °, preferably by an angle of about 45 ° to 105 °, more preferably by an angle of about 60 °.

12. The stirring system of claim 11, wherein the stirrer (3) comprises:

a. a longitudinal axis (49), and

b. shaft (30)

c. Wherein the shaft (30) has at least one stirring element (4) extending away from the shaft (30),

d. the stirring element (4) also has a profile or envelope that narrows at least partially away from the shaft (30), substantially transverse to the longitudinal axis (49).

13. Stirring system according to claim 12, wherein the stirrer (3) has a plurality of stirring elements (4), the stirring elements (4) being arranged in at least two groups of at least two stirring elements (4) each at respective positions along the longitudinal axis, the stirring elements (4) of adjacent groups being arranged offset with respect to each other.

14. Stirring system according to claim 13, wherein the stirring element (4) can be formed such that it corresponds to the contour of the baffle (2) during rotation in the operating state.

15. A stirring system according to claim 14, wherein the stirring system is at least partially, preferably completely, composed of an oxide-dispersion-hardened PGM material.

16. Stirring system according to claim 15, wherein the baffles (2) and/or the stirrer (3), preferably the stirring element (4), have voids in order to reduce weight or provide further compression of the molten glass.

17. A method of assembling a stirring system for molten glass as claimed in at least one of the respective preceding claims, the steps of the method being as follows:

a. introducing the stirrer (3) into the stirred vessel (1) by at least one axial or translational relative movement of the stirrer (3) with respect to the stirred vessel (1),

b. further subsequent or synchronous movement is achieved by relative rotation of the stirrer (3) with respect to the stirred vessel (1), and

c. the stirrer (3) is further axially translated relative to the stirred vessel (1).

18. A method of stirring molten glass using a stirring system according to at least one of claims 1 to 16, the method comprising the steps of:

a. feeding molten glass through an inlet (11) of the stirring vessel (1),

b. rotating the stirrer (3) in the stirring vessel (1) and passing molten glass through the interior of the stirring vessel (1),

c. the molten glass is guided through the constriction formed between the stirring element (4) and the baffle (2) and is comminuted, kneaded and/or pressed during the rotation of the stirrer (3) and the passage of the molten glass through the interior of the stirring vessel (1), and

d. discharging molten glass through an outlet (12) of the stirred vessel (1).