Description

The current disclosure relates to a refractory impact pot comprising a bottom having an impact surface and comprising a wall having an inner surface, the wall extending from said bottom upwardly to an upper end of the impact pot, the inner surface of the wall and the impact surface defining an inner space, wherein a number of horizontal barriers is provided, the number of horizontal barriers projecting in a protrusion direction from the inner surface of the wall into the inner space.

A refractory (i.e. , fireproof) impact pot, also called impact pad, for a metallurgical vessel, e.g., a tundish, usually has a tub like shape comprising a bottom with an upper impact surface and a wall with an inner surface. The wall extends from said bottom upwardly to an upper end of the impact pot. The inner surface of the wall and the impact surface of the bottom define a central inner space of the impact pot.

Liquid metal is poured into a metallurgical vessel and impact pots are placed inside the metallurgical vessel for reducing turbulences and splashing of the metal melt during and also after pouring. To further improve the turbulence and splashing behavior various constructional amendments have been made to the generic type of an impact pot. In WO 95/13890 A1 an annular portion which extends inwardly and upwardly towards the circumferential upper end of the impact pot is disclosed. In WO 03/082499 A1 one or more portions of the circumferential upper end of the impact pot support so called overhangs which project inwardly into the central space of the impact pot. In WO 2012/012853 A1 the inner surface of the wall is provided with barriers of rectangular shape while the impact surface of the bottom provides corrugations. EP 2 769 785 B1 discloses inverted “V”- or “W’ -shaped barriers at the inner surface of the wall and therefore provides further reduction of turbulences. All known impact pot designs are having problems handling misalignment of a ladle shroud (or a similar nozzle), by which the metal melt is fed into said impact pot. Off-centered and/or angled pouring of metal melt by a misaligned ladle shroud or nozzle might then result in splashing of the metal melt at the beginning of a casting process and unfavorable flow pattern during steady state casting, potentially resulting in reduced product quality.

It is therefore an object to provide an impact pot which further improves flow properties of metal melts poured into said impact pot, in particular for off-centered and/or angled pouring of the melt.

This object has been achieved by providing an impact pot comprising a plurality of vertical barriers, projecting in protrusion direction from the inner surface of the wall into the inner space, wherein the plurality of vertical barriers is arranged below the number of horizontal barriers which is adjacent to the respective vertical barrier. A vertical channel can be defined by side walls of two adjacent vertical barriers and by the corresponding side wall of the impact pot.

The vertical barriers being located below the adjacent horizontal barriers means the center of mass of vertical barriers is located below the center of mass of adjacent horizontal barriers. “Below” can also be considered to be closer to the bottom or farther from the upper end.

“A number of” means “at least one”, whereas “a plurality of” means “at least two”. Also, “adjacent” is considered as neighboring (or in other words consecutive or sequential) but with a distance, i.e. , not abutting. Therefore, vertical barriers are per definition distanced vertically from adjacent horizontal barriers. As vertical barriers are located below adjacent horizontal barriers, vertical barriers which are not adjacent to said horizontal barriers (as they are located on another section of a wall or on the same wall section but are not the next vertical barrier in circumferential direction, i.e., not neighboring) might also be located (partially or in total) above said non-adjacent horizontal barriers. It is preferable when the vertical barriers of one wall section (e.g., on one side of an impact pot having a polygonal, e.g., rectangular, shaped impact surface) are located below all horizontal barriers of said wall section. This leads to symmetrical flow behavior on this wall section. It is even more preferable when the plurality of vertical barriers is located below all horizontal barriers. This leads to symmetrical flow on all sides of the wall.

The impact pot can be used in a metallurgical vessel, e.g., a tundish, for reducing turbulences and splashing of liquid metal melt being poured into said metallurgical vessel during and also after pouring.

A symmetrical flow of liquid metal in the impact pot results in a symmetrical flow downstream in the tundish, which provides several benefits to the process such as: homogeneous temperature and composition among the different strands; higher residence times with consequently improved removal of non-metallic inclusions by flotation; lower tendency of vortex formation in the strands, reducing the risk of slag contamination into the mold and mold level fluctuations; reduced wall shear stresses in the refractory lining with consequently better refractory life; and lower turbulence in the slag interface resulting in a lower risk of reoxidation of the steel bath. It has been shown that by using a number of horizontal barriers and a plurality of vertical barriers as disclosed herein, liquid metal being poured into the impact pot evenly distributes inside a tundish where such an impact pot is placed in. This also is the case if the liquid metal stream is poured at a non- orthogonal angle into the impact pot and onto the impact surface and/or if the liquid metal stream is misaligned from the center of the impact pot. This effect is achieved because the at least one horizontal barrier and the plurality of vertical barriers arranged below the at least one horizontal barrier which is adjacent to the respective vertical barrier act as a diffuser for the metal stream poured into the impact pot and flowing out of the impact pot into the surrounding tundish. When liquid metal is poured misaligned from the center of an impact pot in a misalignment direction, the liquid metal might show a tendency to flow out of the impact pot on the side opposing the misalignment direction, as that is the path of least resistance. This causes an uneven distribution of the flow of liquid metal in the tundish. As the plurality of vertical barriers is located below the number of horizontal barriers, which is adjacent to the respective vertical barrier, the flow of liquid metal is distributed evenly throughout the entire cross-section of the impact pot. The main effects and advantages of the vertical barriers are: (1 ) to break the, possibly asymmetrical, horizontal velocity components of the liquid metal flow and (2) to promote ascending flow throughout the entire horizontal cross-section of the impact pot, avoiding a strong upward flow concentrated only in the opposite side related to an off-centered incoming liquid metal jet. However, the vertical barriers are not able to completely homogenize the flow, as different vertical channels (between adjacent vertical barriers) can have different vertical flow velocities, due to each vertical channel being in a different position related to the liquid metal jet impact area. To achieve proper symmetrical flow, it is desirable that the vertical velocities of the liquid metal flow at a given vertical channel are neither higher nor lower than the average ascending liquid metal flow velocity. The liquid metal upwardly flowing through the vertical channels collides with horizontal barriers located above (being adjacent to the vertical barriers which border the vertical channel), resulting in the following advantages: (1 ) homogenization of the flow velocities between adjacent vertical channels, due to the mixing generated as the flows from adjacent vertical channels are forced against each other after colliding with horizontal barriers located above; (2) dissipation of kinetic energy of the flow caused by the longer path the fluid needs to take to go around the horizontal barriers after colliding with them. Therefore, the vertical barriers significantly enhance the functionality of the horizontal barriers, by channeling the flow directly against them. On the other side horizontal barriers equalize different vertical velocities within different vertical channels in order to avoid flow asymmetry. The collision of the vertical flow of liquid metal with the horizontal barriers located above might also have the effect of promoting minor, localized turbulences which help achieving abovementioned effects. The combination of both vertical and horizontal barriers as disclosed herein provides a homogeneous flow out of the impact pot and into in the tundish, even under unfavorable conditions of severe misalignment of the ladle shroud or nozzle. The number of horizontal barriers combined with the plurality of vertical barriers located below according to this disclosure allow effectively equalizing both the distribution of the incoming steel in the tundish and dissipating its kinetic energy. This effect is even achieved under unfavorable conditions of severe misalignment of the incoming liquid metal jet.

Vertical barriers and adjacent horizontal barriers are not abutting, in the sense that there is some opening where the incoming flow from adjacent vertical channels can mix and be equalized after colliding with the horizontal barriers.

The circumferential direction runs horizontally along the inner surface, clockwise viewed from above. A vertical direction is seen as directing perpendicularly from the impact surface of the bottom to the upper end of the wall. If the inner surface of the wall is perpendicular to the impact surface of the bottom, the vertical direction is parallel to the inner surface of the wall. A protrusion direction is seen as directing perpendicularly from the inner surface of the wall into the inner space of the impact pot. If the inner surface of the wall is perpendicular to the impact surface of the bottom, the protrusion direction is parallel to the impact surface of the bottom. A barrier can be defined by its horizontal dimension, its vertical dimension, and its protrusion dimension. The horizontal dimension is the dimension in circumferential direction, the vertical dimension is the dimension in vertical direction, the protrusion dimension is the dimension in protrusion direction.

In this disclosure, a vertical barrier is defined as a barrier which has at least a portion having a larger vertical dimension than horizontal dimension while a horizontal barrier is defined as a barrier which has at least a portion having a larger horizontal dimension than vertical dimension. A vertical barrier can also be defined as a barrier whose bounding box has a larger vertical dimension than horizontal dimension. A bounding box is the smallest cuboidal box which can fully contain the barrier in its interior. Preferably a vertical barrier in total has a larger vertical dimension than horizontal dimension and/or a horizontal barrier has a larger horizontal dimension than vertical dimension. Preferably a vertical barrier has a vertical dimension that is at least 10 % larger, preferably 25% larger, most preferably 50% larger, than its horizontal dimension. Preferably the horizontal barrier has a horizontal dimension that is at least 10% larger, preferably 25% larger, most preferably 50% larger, than its vertical dimension. The upper end of the impact pot can be closed along the circumference of the wall or might also have gaps and/or slits (as disclosed in EP 2 418 032 B1 or similar) and/or another profile. Also holes through the wall can be provided to push flow towards regions of the tundish where the liquid metal flow might otherwise be having a lower temperature or might be stagnant. This is particularly advantageous in tundish configurations with multiple strands, in which strands located further away from the impact pot might receive steel with a lower temperature compared to the strands located closer to the impact pot. In such situations, holes in the wall of the impact pot might be beneficial to direct some of the incoming flow with a higher temperature to these distant regions.

If exactly one horizontal barrier is used, this horizontal barrier might be provided along the whole circumference or part of the circumference of the inner wall as lip or overhang.

Preferably, a plurality of horizontal barriers is provided, wherein the plurality of vertical barriers is arranged at least partially within horizontal gaps between horizontal barriers which are adjacent to the respective vertical barrier. As “adjacent” is defined as neighbouring and not abutting, vertical barriers are distanced vertically from adjacent horizontal barriers. Providing a plurality of horizontal barriers leads to even better reduction of turbulences of the metal melt. A plurality of horizontal barriers can allow vertical channels (in horizontal gaps between two adjacent vertical barriers) to have its associated horizontal barrier located above it, which increases the synergy effect of vertical and horizontal barriers in order to dissipate kinetic energy and homogenize the flow.

It is advantageous to arrange a plurality of horizontal barriers and a plurality of vertical barriers alternately along the circumference of the inner surface of the wall. By doing so the abovementioned advantages are further increased, since the total kinetic energy of the incoming liquid metal jet is distributed among different vertical barriers and horizontal barriers located along the circumference and each vertical channel has its associated horizontal barrier located above it. The horizontal gap between adjacent horizontal barriers also increases the overall cross-section of the impact pot opening, compared to a situation in which there are no horizontal gaps. A larger horizontal cross-section of the impact pot opening allows for a more diffused flow out of the impact pot into the tundish. If the liquid metal flows through a larger area, its average velocity is consequently lower, which increases the residence time and reduces undesirable turbulences in the tundish. The horizontal gap between adjacent horizontal barriers preferably is at least 5 mm to 10 mm and at most 40 to 60 mm.

The number of horizontal barriers may have an upper surface comprising one or more of the following shapes and orientations: inclined in protrusion direction, declined in protrusion direction, neither inclined nor declined in protrusion direction, curved in horizontal circumferential direction of the inner surface, inclined in circumferential direction of the inner surface, declined in circumferential direction of the inner surface, neither inclined nor declined in circumferential direction of the inner surface. Declined means falling and inclined means rising, so that (under the assumption of having inner surfaces perpendicular to the impact surface of the bottom) an upper surface declining in protrusion direction is approaching the impact surface of the bottom, wherein an upper surface inclining in protrusion is distancing from the upper surface of bottom. If the inner surface of the wall is at an angle non-perpendicular to the impact surface of the bottom the protrusion direction is non-parallel to said impact surface and it is preferable when the upper surface of the number of horizontal barriers is inclined or declined in protrusion direction such that it is parallel to the impact surface of the bottom and/or the horizontal plane (the bottom might be inclined or declined etc. from the horizontal plane).

It is most preferable if the upper surface of horizontal barriers is declined in protrusion direction. This means the upper surface is approaching the impact surface of the bottom if the inner surface of the wall is perpendicular to the upper impact surface of the bottom. If the inner surface of the wall is non-perpendicular to the upper impact surface of the bottom it also is preferable of the upper surface being declined such that it is approaching the impact surface of the bottom. The declination of the upper surface is beneficial in case an off-centered liquid metal jet collides with the upper surface of the horizontal barriers. Compared to an upper surface of a horizontal barrier which is not declined in the protrusion direction, a declined upper surface has the advantage of directing the incoming flow hitting said upper surface towards the inner space of the impact pot, thereby reducing splashing.

It is particularly advantageous for the number of horizontal barriers to have alternating inclining and declining upper surfaces in circumferential direction of the inner surface. Declined again means falling and inclined again means rising, so that an upper surface declining in circumferential direction is approaching the bottom, wherein an upper surface inclining in protrusion is distancing from the bottom.

This can be the case if only one horizontal barrier is provided, but also if a plurality of horizontal barriers is provided, e.g., in the shape one or more inverted “V”s. This shape has the advantage of reducing splashing in case an incoming off-centered liquid metal jet hits the top surface of the horizontal barrier, as this shape guides the incoming jet downward towards the inner space of the impact pot, reducing the effect of molten steel droplets splashing upwards, which would be a safety concern in the steel mill. A plurality of horizontal barriers as disclosed in EP 2 769 785 B1 might be used. Angles between the inclined and declined upper surfaces may vary between > 45 degrees and < 170 degrees with a preferred lower value of > 90 degrees and a preferred upper value of < 140 degrees. Instead of a specific angle between the inclined and declined upper surfaces the transition area between the inclined and declined upper surfaces may be curved. The inclining and declining upper surfaces may have the same or different length. The upper surfaces inclining and declining in circumferential direction can be shaped as straight legs or at least with straight sections but may be curved as well, for example convex or concave. Also, upper surfaces can be inclining and/or declining in circumferential direction while also being inclining and/or declined in protrusion direction. The number of horizontal barriers might have a lower surface perpendicular to the inner wall (i.e., neither inclined nor declined in protrusion direction) and parallel to the circumferential direction (i.e., neither inclined nor declined in circumferential direction), even if the upper surface might be inclined and/or declined in protrusion direction and inclined and/or declined in circumferential direction. The number of horizontal barriers having a lower surface perpendicular to the inner wall is advantageous for the flow properties of the liquid metal and also allows for easier production of the number of horizontal barriers. The number of horizontal barriers might also have a lower surface parallel to the upper surface.

The cross-sectional profile of the number of horizontal barriers along the circumferential direction (i.e., in the plane spanning between the protrusion direction and the vertical direction) may vary. It may be, e.g., polygonal (e.g., rectangular or triangular), semicircular, oval etc. Combinations of those shapes may also be used.

Preferably the plurality of vertical barriers have an upper surface comprising one or more of the following shapes and orientations: inclined in protrusion direction, declined in protrusion direction, neither inclined nor declined from protrusion direction, curved in circumferential direction of the inner surface, inclined in circumferential direction of the inner surface, declined in circumferential direction of the inner surface, neither inclined nor declined in circumferential direction of the inner surface. Declined means falling and inclined means rising, so that (under the assumption of having inner surfaces perpendicular to the impact surface of the bottom) an upper surface declining in protrusion direction is approaching the impact surface of the bottom, wherein an upper surface inclining in protrusion is distancing from the impact surface of the bottom. If the inner surface of the wall is at an angle non-perpendicular to the impact surface of the bottom the protrusion direction is non-parallel to said impact surface and it is preferable when the upper surface of the plurality of horizontal barriers is inclined or declined in protrusion direction such that it is parallel to the inner surface of the bottom and/or the horizontal plane (the bottom might be inclined or declined etc. from the horizontal plane). If a vertical barrier is at least partially located within a horizontal gap between horizontal barriers adjacent to the respective vertical barrier and the upper surface of said vertical barrier is not parallel to the circumferential direction and has a peak, e.g., due to inclined and/or declined portions or rounded portions, the peak may extend above the lower surface or even to some extent above the upper surface of said horizontal barriers adjacent to said vertical barrier. Nonetheless in this case this vertical barrier is still considered as being located below the horizontal barriers adjacent to said vertical barrier. In general, the center of mass of the vertical barrier can be considered to be below the mass center of horizontal barriers adjacent to said vertical barrier.

Preferably side walls of the number of vertical barriers are plane, preferably perpendicular to the impact surface of the bottom. The side walls also might be curved or unregular. The side walls of the number of vertical barriers might meet the inner surface of the wall at a side wall angle of 75-105 degrees, preferably 80- 100 degrees, most preferably 90-95 degrees. This side wall angle describes the “outer angle”, i.e. , viewed from the inner space and not the “inner angle” viewed from within the vertical barriers. Side walls meeting the inner surface of the wall at a side wall angle of 90 degrees are perpendicular to the inner surface of the wall. The side walls of the vertical barriers can meet the impact surface of the bottom at an angle of 75-105 degrees, preferably 80-100 degrees, most preferably 90-95 degrees. A 90-degree angle intensifies the effect of breaking horizontal velocity components of the liquid metal flow along the impact surface of the bottom. Angles of above 90 degrees allow for an easier production of the impact pot, therefore an angle slightly above but close to 90 degrees might be preferable.

Preferably the walls - measured from the impact surface to the upper edge of the wall - of the impact pot have a, e.g., constant, height of 100-400 mm, preferably 105-380 mm. Typical wall height values are 105 mm, 160 mm, 180 mm, 210 mm, 235 mm, 250 mm or 380 mm.

Preferably the distance between the closest points of adjacent vertical and horizontal barriers is at least 5 mm, most preferably at least 10 mm. Preferably the distance between the closest points of adjacent vertical and horizontal barriers is at most 50%, most preferably at most 85%, of the wall height.

The plurality of vertical barriers might project 5-15% into the inner space regarding to the diameter of the inner space in protrusion direction of the respective vertical barrier. The diameter of the inner space in protrusion direction describes the diameter from the inner surface of the wall at the location of the respective vertical barrier to the opposing inner surface of the wall. If the impact surface of the bottom is rectangular and has dimensions of 520 x 720 mm with vertical barriers projecting 5-15% into the inner space regarding to the diameter of the inner space in protrusion direction of the respective vertical barrier, this would lead to a protrusion into the inner space of 26-78 mm for the wall section having 520 mm inner surface length (i.e. , the vertical barrier is arranged at the wall section having 720 mm inner surface length) and a protrusion into the inner space of 36-108 mm for the wall section having 720 mm inner surface length (i.e., the vertical barrier is arranged at the wall section having 520 mm inner surface length).

Preferably vertical barriers on at least one side wall project at least 26 mm and/or at most 78 mm into the inner space. Preferably vertical barriers on at least one side wall project at least 36 mm and/or at most 108 mm into the inner space.

Preferably the plurality of vertical barriers project at least 10 mm and/or at most 75 mm into the inner space. The plurality of vertical barriers might also project at least 26 mm and/or at most 108 mm into the inner space.

The plurality of vertical barriers may have a height of 25-70%, with regard to the total inner surface height of the abutting wall, preferably 25-60%. The latter is particularly preferable when the inner surface height of the adjacent wall is below 300 mm.

Preferably the plurality of vertical barriers has a height of at least 25 mm, most preferably at least 35. Preferably the plurality of vertical barriers is arranged abutting to the impact surface of the bottom. Vertical barriers located abutting to the impact surface of the bottom (or distanced, but so close to the impact surface of the bottom that it effects the flow as if it was abutting) are beneficial for flow distribution since the (asymmetric) flow typically runs parallel to impact surface of the bottom after the (off-center) liquid metal jet collides with said impact surface, therefore it is preferable to arrange the vertical barriers closely to the impact surface of the bottom, to maximize their ability to intercept the flow streams of the liquid metal and channel them upwards.

The plurality of vertical barriers can also be arranged at a distance, e.g., at least 5 mm and/or at most 40 mm, from the impact surface, wherein preferably the plurality of vertical barriers is arranged at the same distance from the impact surface. It is also possible that adjacent vertical barriers are connected to each other on the lower side or are placed on a ridge running on the impact surface alongside the inner wall. This ridge can also be considered to be part of the bottom of the impact pot wherein the vertical barriers are placed on said bottom. Of course, also one or some vertical barriers can be arranged abutting to the impact surface wherein one or more other vertical barriers are arranged at a distance from the impact surface.

The plurality of vertical barriers preferably is arranged at a distance, preferably at the same distance from the upper end of the impact pot. The different reference (impact surface of the bottom or upper end of the impact pot) may be important in case of profiled impact surfaces and/or an upper end of the impact pot which is (at least in part) not parallel to the horizontal, e.g., having inclined or declined surfaces in circumferential direction.

Preferably the number of horizontal barriers is arranged at a distance, preferably at least 5 mm and/or at most 40 mm, from the upper end of the impact pot. Such an arrangement does not decrease the cross-section of the opening at the upper end of the impact pot. The larger the cross-section of the opening at the upper end of the impact pot, the larger the tolerance for the deviation from the ideal (center) position by the incoming liquid metal jet. If a plurality of horizontal barriers is provided, preferably the plurality of horizontal barriers is arranged at the same distance from the upper end of the impact pot. Of course, some horizontal barriers can also be arranged abutting to the upper end of the impact pot wherein other horizontal barriers are arranged at a distance from the upper end of the impact pot. The number of horizontal barriers is arranged at a distance from the impact surface. If a plurality of horizontal barriers is provided, preferably the plurality of horizontal barriers is arranged at the same distance from the impact surface. Again, the different reference (impact surface of the bottom or upper end of the impact pot) may be important in case of profiled impact surfaces and/or an upper end of the impact pot which is (at least in part) not parallel to the horizontal, e.g., having inclined or declined surfaces in circumferential direction.

It is also possible to provide an additional number of horizontal barriers arranged at another distance from the upper end of the impact pot as the initial number of horizontal barriers. In particular two or more rows of horizontal barriers can be provided to further homogenize the incoming flow from different vertical channels.

Preferably the horizontal barriers project 2.5 to 15% into the inner space regarding to the diameter of the inner space in protrusion direction of the respective horizontal barrier., The diameter of the inner space in protrusion direction describes the diameter from the inner surface of the wall at the location of the respective vertical barrier to the opposing inner surface of the wall.

Preferably the horizontal barriers project at least 5 mm and/or at most 75 mm into the inner space.

It is advantageous when the protrusion length of the vertical barriers exceeds the protrusion length of the horizontal barriers. The protrusion length of the vertical barriers is preferably 20-100% larger compared to the protrusion length of the horizontal barriers. A larger protrusion length of the vertical barriers increases the probability of horizontal streams at the bottom impact surface colliding with said vertical barriers, with no significant drawbacks. Although the horizontal barriers also benefit from protrusion length, a larger protrusion length for the horizontal barriers results in a reduced cross-section in the area of the upper opening of the impact pot, as these are located close to or at the upper end of the impact pot. If the abovementioned cross-section shall not be reduced in excess, it might be preferable to have a smaller protrusion length of the horizontal barriers than that of the vertical barriers.

Preferably the plurality of vertical barriers overlaps with the number of horizontal barriers, which is adjacent to the respective vertical barrier in circumferential direction of the inner surface. This arrangement ensures that any liquid metal jet flowing upwardly within the vertical channels (i.e. , between adjacent vertical barriers) collides with a horizontal barrier located above, enhancing the homogenization effect of the liquid metal flow. If a plurality of horizontal barriers is provided the vertical barriers can overlap with all adjacent horizontal barriers in circumferential direction. If a plurality of horizontal barriers is provided the plurality of vertical barriers can overlap with one or both horizontal barriers, which is/are adjacent to the respective vertical barrier in circumferential direction of the inner surface.

The plurality of vertical barriers can be distanced to the number of horizontal barriers, which is adjacent to the respective vertical barrier in circumferential direction of the inner surface. This is advantageous in situations where it is desired to increase the cross section in the area of the upper opening of the impact pot for higher liquid metal flow rates. If a plurality of horizontal barriers is provided the plurality of vertical barriers can overlap with one or both horizontal barriers, which is/are adjacent to the respective vertical barrier in circumferential direction of the inner surface.

The plurality of vertical barriers can also be arranged in such a way that they are neither distanced from nor overlapping with the number of horizontal barriers, which is adjacent to the respective vertical barrier in circumferential direction of the inner surface. This means that there can be no overlap and no gap between the concerning vertical barrier and horizontal barriers which is adjacent to said vertical barrier in circumferential direction of the inner surface. Still there is a gap in vertical direction. This represents an intermediate configuration between ensuring that every stream flowing upwardly within the vertical channels (i.e., between adjacent vertical barriers) collides with the respective horizontal barriers located above and keeping the cross-section in the area of the upper opening to a maximum. If a plurality of horizontal barriers is provided the plurality of vertical barriers can be arranged in such a way that they are neither distanced from nor overlapping with one or both number of horizontal barriers, which is/are adjacent to the respective vertical barrier in circumferential direction of the inner surface.

If a plurality of horizontal barriers and a plurality of vertical barriers are arranged alternately along the circumference of the inner surface of the wall with no gap in circumferential direction in between (there might be an overlap), this may lead to an overall arrangement wherein a metal melt flowing along the surface of the inner wall of the impact pot will contact at least one of the vertical or horizontal barriers. A plurality of horizontal barriers and a plurality of vertical barriers can also are arranged alternately along the circumference of the inner surface of the wall with a gap in circumferential direction in between.

The impact pot can be manufactured by casting, pressing, injection molding or 3D printing and can comprise basic or non-basic refractory materials. Production of a corresponding impact pot may include use of a so called "lost template", for example a template of a combustible material which will be burnt off after production of the impact pot. The impact pot can be produced as one piece or can be assembled from a separate bottom piece and one continuous wall or several wall sections. The impact surface may have any shape, e.g., trapezoidal, triangular, round, oval etc., wherein a rectangular shape is preferred.

Preferably the vertical barriers and/or horizontal barriers are an integral part of the abutting wall, i.e. , are produced in one piece with said wall - in other words, the wall and the barriers are provided by one ceramic part.

Preferably the wall of the impact pot, and its upper end, has no or at least no substantial protrusion towards the inner space of the impact pot, to provide the inflow area with largest possible cross-section, and to avoid splashing of the metal melt even in the case of misalignment of the liquid metal jet. Figs. 1 to 12 show exemplary, schematic, and non-limiting advantageous embodiments of the invention wherein

Fig. 1 shows an impact pot having one horizontal barrier and a plurality of vertical barriers,

Fig. 2 shows an impact pot having a plurality of horizontal barriers and a plurality of vertical barriers,

Fig. 3 shows the impact pot of Fig. 2, wherein the vertical barriers are placed on a ridge of the bottom of the impact pot,

Fig. 4 shows the impact pot of Fig. 2, wherein side walls of vertical barriers meet the inner surface of the walls of the impact pot at an angle of 95 degrees,

Fig. 5 shows an impact pot having a plurality of horizontal barriers with upper surfaces being inclined and declined in circumferential direction and declined in protrusion direction and a plurality of vertical barriers,

Fig. 6 shows the impact pot from Fig. 5, wherein side walls of vertical barriers meet the inner surface of the walls of the impact pot at a side wall angle of 95 degrees,

Fig. 7 shows the impact pot of Fig. 6 but with vertical barriers having upper surfaces being declined in protrusion direction,

Fig. 8 shows the impact pot of Fig. 6 but with vertical barriers having upper surfaces being inclined and declined in circumferential direction in a roof manner,

Fig. 9 shows the impact pot of Fig. 6 but with vertical barriers having upper surfaces being convexly curved in circumferential direction,

Fig. 10a, b, c shows a portion of an inner surface of a wall of the impact pot displayed in Fig. 5 and two other embodiments, Fig. 11a shows a flow simulation of molten metal inside an impact pot according to the Prior Art,

Fig. 11 b shows a simulation of the flow of molten metal inside the impact pot of Fig. 5,

Fig. 12 shows detailed areas of the flow of molten metal.

Figs. 1 to 9 each show impact pots 1 comprising a bottom 10 with an upper impact surface 10s and a wall 12 having an inner surface 12i, wherein the wall 12 extends from said bottom 10 upwardly to an upper end 14 of the impact pot 1. The inner surface 12i of the wall 12 and the upper impact surface 10s of the bottom 10 define an inner space 16, having an inlet/outlet opening 18 for a melt at the upper end 14. The opening 18 in the Figs, is rectangular by way of example.

Figs. 1 a to 9a respectively show a section cut of an impact pot 1 , wherein the impact pot 1 is cut in half. Figs. 1 b to 9b each show a section cut of the same impact pot 1 as respective Fig. 1a to 9a, wherein a quarter of the impact pot 1 is cut off at a corner such that two sections of the wall 12 are cut in half. These cuts in Figs. 1a to 9a and 1b to 9b of course are only made for easier depiction.

A circumferential direction h is defined horizontally, i.e. , along the circumference of the inner surface 12i of the wall 12 and is directed clockwise from the upper perspective. Also, a protrusion direction p perpendicularly from the inner surface 12i into the inner space 16 is defined, as well as a vertical direction v from the impact surface 10s of the bottom 10 to the upper edge 14 of the wall 12.

The bottom 10 and correspondingly the impact surface 10s shown in Figs. 1 to 9 is of rectangular shape only by way of example, whereas the bottom 10 may have any shape, e.g., trapezoid, triangular, round, oval etc. wherein also the edges can be rectangular, have another angle or can be rounded etc. Also, the impact surface 10s does not necessarily have to have the same shape as the bottom 10, e.g., because the wall 12 might have varying thickness. Exemplary dimensions of a rectangular impact surface 10s might be 520 x 720 mm or 220 x 250 mm or any other size. The wall 12 preferably is vertical, i.e. , meets the impact surface 10s of the bottom 10 with an angle of 90 degrees, but might also be inclined or declined, preferably inclined outwards at an angle of 7 to 10 degrees. The inclination angle of the wall 12 might be chosen to match an inclination angle of a wall of a tundish the impact pot 1 is to be used in. Also, the impact surface 10s might be structured and/or comprise inclined and/or declined sections. The upper end 14 of the impact pot 1 preferably is closed along the circumference of the wall 12, as shown in the Figs., but might also have gaps and/or slits and/or another profile. The upper end 14 of the impact pot 1 might also have sections which are inclined or declined in circumferential direction h.

Preferably the inner surface 12i of the wall 12 has a height from 225 mm to 300 mm. The wall 12 might be closed as shown in the figures or might also comprise through holes.

The impact pots 1 shown in Figs. 1 to 9 comprise a number of horizontal barriers 2, the number of horizontal barriers 2 projecting in protrusion direction p from the inner surface 12i of the wall 12 into the inner space 16 and further comprise a plurality of vertical barriers 3, projecting in protrusion direction p from the inner surface 12i of the wall 12 into the inner space 16, wherein vertical barriers 3 are arranged below the number of horizontal barriers 2 which is adjacent to the respective vertical barrier 3. The number of horizontal barriers 2 has an upper surface 2u, a lower surface 2c and may have a front surface 2f.

A barrier can be defined by its horizontal dimension (in circumferential direction h), its vertical dimension (in vertical direction v), and its protrusion dimension (in protrusion direction p). In this disclosure, a vertical barrier 3 is defined as barrier which has at least a portion having a larger vertical dimension than horizontal dimension while a horizontal barrier 2 is defined as barrier which has at least a portion having a larger horizontal dimension than vertical dimension. Preferably a vertical barrier 3 has in total a larger vertical dimension than horizontal dimension and a horizontal barrier 2 has a larger horizontal dimension than vertical dimension as disclosed in the Figures. Fig. 1 shows an impact pot 1 having one horizontal barrier 2 in the form of a projecting lip, wherein advantageously the horizontal barrier 2 is located at the upper end 14 of the wall 12. The horizontal barrier 2 has an upper surface 2u located in vertical direction v as defined herein, a front surface 2f located towards the inner space 18 (i.e. , in protrusion direction p) and a lower surface 2u located towards the impact surface 12s (i.e., against the vertical direction v as defined herein). The upper surface 2u here is part of the upper end 14 of the wall 12 but might also be distanced vertically from the upper end 14 of the wall 12.

The front surface 2f might also be omitted if the upper surface 2u and the lower surface 2c meet at an angle. The horizontal barrier 2 might also be interrupted and/or placed at a distance from the upper end 14 of the wall 12.

Furthermore, a plurality of vertical barriers 3, by way of example of cuboid shape, is arranged distanced vertically by a vertical gap from the horizontal barrier 2. The vertical gap might also vary along the circumferential direction h depending on the shape and location of the respective vertical barriers 3 and/or the respective horizontal barrier 2. The vertical barriers 3 have an upper surface 3u located in vertical direction v as defined herein, a front surface 3f located towards the inner space 18 (i.e., in protrusion direction p) and side surfaces 3s in and against circumferential direction h, i.e., one side surface 3s in clockwise direction and one side surface 3s in counterclockwise direction. As the vertical barriers 3 are of cuboid shape, the upper surfaces 3u of the vertical barriers 3 are flat, i.e., neither inclined nor declined in circumferential direction h or protrusion direction p and side walls 3s of vertical barriers 3 meet the inner surface 12i of the walls 12 of the impact pot 1 at a side wall angle a of 90 degrees. This side wall angle a describes the “outer angle”, i.e., viewed from within the inner space 16 and not the “inner angle” viewed from within the vertical barriers 3.

As the vertical barriers 3 are cuboid-shaped they have a cuboid-shaped base. The vertical barriers 3 shown here are abutting on the bottom 10. If the vertical barriers 3 would not be abutting on the bottom 10 they could comprise a rectangularshaped lower surface located towards the impact surface 12s (i.e., against the vertical direction v as defined herein). Adjacent vertical barriers 3 are arranged having a horizontal gap G3 in between in circumferential direction h, see Fig. 10 regarding the horizontal gap G3. The horizontal gap G3 of course might vary.

Fig. 2 shows an impact pot 1 , wherein a plurality of horizontal barriers 2 and a plurality of vertical barriers 3 is provided, wherein the plurality of vertical barriers 3 is arranged at least partially within horizontal gaps G2 of adjacent horizontal barriers 2, see Fig. 10. The horizontal barriers 2 (and vertical barriers 3) by way of example have cuboid shape. Therefore, the upper surfaces 2u of horizontal barriers 2 and the upper surfaces 3u of vertical barriers 3 are flat, i.e. , neither inclined nor declined in circumferential direction h or protrusion direction p and side walls 3s of vertical barriers 3 and side walls 2s of horizontal barriers 2 meet the inner surface 12i of the walls 12 of the impact pot 1 at a side wall angle a of 90 degrees.

It is particularly preferable if vertical barriers 3 and/or horizontal barriers 2 have side wall angles a of 75-105 degrees, more preferably 80-100 degrees, most preferably 90-95 degrees are provided.

Fig. 3 shows the impact pot 1 of Fig. 2, wherein the vertical barriers 3 are placed on a ridge running on the impact surface 10s alongside the inner wall 12i of the impact pot 1 . This ridge can be considered to be part of the bottom 10, wherein the vertical barriers 3 are placed on said bottom 10.

Fig. 4 shows the impact pot 1 of Fig. 2, wherein side walls 3s of vertical barriers 3 meet the inner surface 12i of the walls 12 of the impact pot 1 at a side wall angle a of 95 degrees (for easier display reasons the reference sign a is only indicated at one vertical barrier 3).

Fig. 5 shows an impact pot 1 having a plurality of horizontal barriers 2 having an upper surface 2u alternatively inclining and declining in circumferential direction h, which leads to a shape of inverted Vs, in other words the plurality of horizontal barriers 2 are arranged in a roof-like shape. A leg angle [3 of 135 degrees between the inclined and declined segments of the upper surfaces 2u is shown as one embodiment. Leg angles [3 between > 45 degrees and < 170 degrees with a preferred lower value of > 90 degrees and a preferred upper value of < 140 degrees may be chosen. The transition area between the inclined and declined segments of the upper surfaces 2u may also be curved. The declining and declining segments of the upper surfaces 2u have the same length by way of example.

Fig. 6 shows the impact pot from Fig. 5, wherein, like in Fig. 4, the side walls 3s of vertical barriers 3 meet the inner surface 12i of the walls 12 of the impact pot 1 at a side wall angle a of 95 degrees and therefore the vertical barriers 3 have a trapezoid base.

Fig. 7 shows the impact pot 1 of Fig. 6 but with upper surfaces 3u being inclined in protrusion direction p.

Fig. 8 shows the impact pot of Fig. 6 but with vertical barriers 3 having upper surfaces 3u being inclined and declined in circumferential direction h in a roof manner, similar to the upper surfaces 2u of the horizontal barriers 2.

Fig. 9 shows the impact pot of Fig. 6 but with vertical barriers 3 having upper surfaces 3u being convexly curved in circumferential direction h.

If a plurality of horizontal barriers 2 is provided the vertical barriers 3 are at least partially positioned within a horizontal gap G2 between adjacent horizontal barriers 2. Adjacent vertical barriers 3 also are arranged having a horizontal gap G3 in between in circumferential direction h. Only by way of example the impact pots 1 shown in Figs. 2 to 9 comprise horizontal barriers 2 and vertical barriers 3 being positioned alternately along the circumference of the inner surface 12i of the wall 12. Also, multiple vertical barriers 3 might be arranged at least partially in a horizontal gap G2 between adjacent horizontal barriers 2 and/or multiple horizontal barriers 3 might be arranged at least partially in a horizontal gap G3 between adjacent vertical barriers 3. The reference signs for horizontal gaps G2 between horizontal barriers 2 and the horizontal gaps G3 between vertical barriers are not shown in Figs. 1 to 9 for tidier depiction but are referred to in Fig. 10. In the embodiments displayed in Figs. 1 to 9 the vertical barriers 3 are arranged abutting to the impact surface 10s. All or some vertical barriers 3 might also be arranged at a distance, preferably at most 40 mm from the impact surface 10s. All or some vertical barriers 3 might also be arranged at the same distance from the impact surface 10s.

Also, in the embodiments displayed in Figs. 1 to 9 the front surfaces 3f of the vertical barriers 3, are by way of example parallel to a plane spanned by the circumferential direction h and the vertical direction v (which in these embodiments means said surfaces 3f are parallel to the inner surfaces 12i of the side walls 12) and therefore meet the impact surface 10s at a side wall angle a of 90 degrees. Furthermore, the front surface(s) 2f of the horizontal barrier(s) 2 is/are by way of example parallel to a plane spanned by the circumferential direction h and the vertical direction v. Of course, the front surfaces 3f of the vertical barriers 3 and/or the front surface(s) 2f of the horizontal bamer(s) 2 may also have another orientation, structure etc.

In the embodiments displayed in Figs. 2 to 9 the horizontal barriers 2 are arranged at the same vertical distance from the upper end 14 of the impact pot 1 . The horizontal barriers 2 might also be arranged at different distances from the upper end 14 of the impact pot 1 . Preferably the horizontal bamer(s) 2 is/are arranged at a distance of at least 5 mm and/or at most 40 mm from the upper end 14.

Figs. 10a, b, c show an inner surface 12i of a wall 12, wherein three different arrangements of a plurality of vertical barriers 3 and a plurality of horizontal barriers 2 are depicted. The circumferential direction h, the vertical direction v and the protrusion direction p are shown, the latter pointing out towards the spectator and the horizontal barriers 2 are only by way of example configured in inverted V- shape. The vertical barriers 3 are only by way of example configured cuboid as depicted in Fig. 5. The plurality of vertical barriers 3 is arranged having a horizontal gap G3 in circumferential direction h and the horizontal vertical barriers 2 are also arranged having a horizontal gap G2 in circumferential direction h. The vertical barriers 3 are arranged at below adjacent horizontal barriers 2. In Fig. 10a the vertical barriers 3 are neither distanced to nor overlapping with all horizontal barriers 2 which are adjacent to the respective vertical barrier in circumferential direction h (indicated by the dashed vertical lines) as depicted in Fig. 5. Fig. 10b shows the same arrangement, wherein the vertical barriers 3 are distanced from horizontal barriers 2 are adjacent to the respective vertical barrier in circumferential direction h, leaving a horizontal gap G1 in between (indicated by the dashed vertical lines), wherein in Fig. 10c the vertical barriers 3 are overlapping with all horizontal barriers 2 which are adjacent to the respective vertical barrier in in circumferential direction h, again indicated by the dashed vertical lines. Of course, it is also possible that only some of the vertical barriers 3 overlap with or are distanced from all or only some adjacent horizontal barriers 2 in circumferential direction h; alternatively, it is also possible that only some vertical barriers 3 are neither distanced from nor overlapping with all or some adjacent horizontal barriers 2 in circumferential direction h. It is also possible that all of the vertical barriers 3 overlap with or are distanced from all or only some adjacent horizontal barriers 2 in circumferential direction h; or that all of the vertical barriers 3 are neither distanced from nor overlapping with only some adjacent horizontal barriers 2 in circumferential direction h.

Despite the exemplary arrangement displayed in Figs. 2 to 9 vertical barriers 3 in each case can be arranged (a) distanced from, or (b) overlapping with or (c) neither distanced to nor overlapping with adjacent horizontal barriers 2.

Vertical barriers 3 and/or horizontal barriers 2 might be an integral part of the abutting wall. The horizontal barriers 2 can have a lower surface 2c that is parallel to the horizontal plane or have a lower surface 2c parallel to the upper surface.

Preferably the vertical barriers 3 protrude 5-15% into the inner space 16 with regard to the inner surface length of the wall 12 in protrusion direction p, preferably at least 10 mm and/or at most 75 mm. The vertical barriers 3 might have a height of 25-60% with regard to the inner surface height of the abutting wall 12. The horizontal barriers 2 may project into the inner space 16 in protrusion direction p at least 10 mm and/or at most 75 mm. The vertical barriers 3 have an upper surface primarily extending in circumferential direction h and in protrusion direction p.

While vertical barriers 3 are located below adjacent horizontal barriers 2, vertical barriers 3 which are not adjacent to said horizontal barriers 2 (as they are located on another section of a wall or on the same wall section but not the next vertical barrier in circumferential direction h, i.e. , not neighboring) might also be located above said non-adjacent barriers. It is preferable when the vertical barriers 3 of one section of the wall 12 (e.g., on one side of an impact pot 1 having a polygonal, e.g., rectangular, shaped impact surface 10s) are located below all horizontal barriers 2 of said wall section and even more preferable when the vertical barriers 3 are located below all horizontal barriers 2 - as shown in Figs. 1 to 9.

It has been shown by computer simulations and water modeling experiments that this impact pot 1 having vertical barriers 3 and horizontal barriers 2 according as disclosed herein reduces the velocity of the metal stream, reduces turbulence within the impact pot 1 , reduces the surface velocity and the surface turbulences within the corresponding metallurgical vessel, compared to all types of prior art devices as mentioned above. This is an indication for a more efficient energy dissipation inside the impact pot 1. Also, a more homogeneous distribution of the metal flow in the tundish is achieved while differences in residence time among the strands are minimized, in particular in the case of a misaligned shroud.

Metal poured into the impact pot 1 hits the impact surface 10s. Any metal stream flowing upwardly within the impact pot 1 (in its inner space 16) in the proximity of a section of the wall 12 is guided by the corresponding vertical barrier 3 and hits a lower surface 2c of the corresponding horizontal barrier 2 barrier, thereby turning inwardly (into the inner space 16) and then upwardly to leave the impact pot via the opening 18. If the metal is poured into the impact pot 1 in an off-center position, to such an extent to cause it to collide with the upper surfaces 2u of the horizontal barriers 2 and/or the upper surfaces 3u of the vertical barriers 3 during pouring, the inclination and/or declination of said upper surfaces 2u and/or 3u will deflect the incoming jet towards the inner space 16 of the impact pot, avoiding splashing of metal droplets upwardly. Fig. 11a shows simulation results for an impact pot having a plurality of horizontal barriers in the shape of inverted “V”s. For depiction reasons a top-front view is chosen, wherein only the impact surface and one wall section are shown, and reference signs are omitted. Flow lines of molten metal are depicted, wherein arrows indicate the flow direction. Although this design works reasonably well for dissipating the incoming kinetic energy and reducing turbulences a misaligned ladle shroud or nozzle still leads to an uneven flow of liquid metal out of the impact pot. Usually, the metal stream drifts to the side opposing the misalignment direction, as that is the path of least resistance. This is shown in Fig. 11 , where liquid metal is poured into the impact pot 1 from a position off-centered to the right, wherein the metal flow drifts to the upper left. This upward flow directed to the side also pulls some flow from the vicinities, which are represented by the incoming flow lines from the upper right corner.

Fig. 11b shows simulation results of the impact pot 1 from Fig. 5 as an example. The same top-front view as in Fig. 11 a is chosen, wherein also like in Fig. 11 a a liquid metal stream is indicated by flow lines with arrows indicating the flow direction. The metal stream is poured into the impact pot 1 the same off-centered way as depicted in Fig. 11a. After impact, the liquid metal stream initially flows parallel to the impact surface 12s towards the opposite side regarding the off- centered jet position. The vertical barriers 3 intercept the metal streams horizontally, break the horizontal velocity components and guide the flow upward against the lower surface 2c of the horizontal barriers 2. The collision between the horizontal metal streams and the vertical barriers might create some swirls at the bottom, between adjacent vertical barriers. This occurs due to the forced change of direction of the flow and are created whenever an obstacle exists in the path of a fluid. Such swirls contribute to ensure the incoming streams are kept within the respective vertical channels and that these streams are forced to flow upward instead of flowing horizontally out of the vertical channel. As the metal streams are guided upwards and collide with the horizontal barriers 2, a local turbulence is generated which causes mixing and homogenization of the velocities from the different vertical streams. These streams then follow the path defined by the gaps G2 between the horizontal barriers 2 and from there are distributed to the tundish with homogeneous velocities and evenly in all directions, without drifting to either side. Similar results have been shown for other embodiments of the impact pot 1 , having a number of vertical barriers 3 and a plurality of horizontal barriers 2 according to this disclosure.

In Fig. 12 the flow at the back side section of the wall 12 is shown in more detail (including more flow lines), wherein different flow areas A, B, C, D, E, F are defined, and other reference signs are omitted for better depiction of the flow lines. Upper opening area A refers to flow out of the upper opening 18; transition area B refers to the transition area between the vertical barriers 3 and the horizontal barriers 2; lower areas C, D, E and F refer to the gap between adjacent vertical barriers 3. The flow is strongest in lower area E, wherein the flow in lower areas C, D and F is weaker in comparison. This is due to the incoming liquid metal stream hitting the impact surface 10s on the right side and therefore in proximity to lower area E. Lower area F is closer to the impact area of the liquid metal stream, but closer to the right wall section, and behind a vertical barrier (not displayed) located at the right wall section of the impact pot, because of which the flow is weaker. The vertical barriers 3 guide the flow towards the horizontal barriers 2. Therefore, the vertical barriers 3 increase the effectiveness of the horizontal barriers 2 as can be seen in transition area B. The horizontal barriers 2 promote mixing between the incoming flow from adjacent vertical channels (built within the gap G3 between two adjacent vertical barriers 3). This results in an equalization of the flow among the different vertical channels: if one vertical channel has a stronger flow than the adjacent channel, caused by the asymmetric flow, the turbulence caused by the collision of the flow with the horizontal barrier 2 will equalize these flows and distribute it evenly afterwards. Therefore, the horizontal barriers 2 increase the effectiveness of the vertical barriers 3 in terms of reducing asymmetries leading to homogeneous flow in upper opening area A, even when the flow varies severely between different lower areas C, D, E, F. Swirls might be generated at the locations where the flow of molten metal collides with an obstacle or with an opposing flow stream. This can be observed in Fig.12 in the regions between the vertical and horizontal barriers, where opposing streams are mixing. The swirls further enhance the equalization effect and are beneficial for reducing velocity differences among adjacent vertical channels.