MXPA98000657A - Apparatus to limit the gas entry to a container - Google Patents

Abstract

The ingress of a gas such as air through the gasket of a drain pipe and a pipe holder of a continuous strainer or a similar abutting surface of a slide gate valve is prevented or inhibited by passing an inert gas into the gas. a channel around the orifice and on the adjoining surface through which air could enter, the gas is uniformly distributed within the channel over the entire configuration of a porous refractory insert that makes contact with the abutting surface of the channel, the porous refractory insert ensures even distribution of the gas to the desired location on the adjoining surface, thereby providing a positive pressure of inert gas that inhibits ambient gas entry

Description

APPARATUS TO LIMIT THE GAS INCOME ft A CONTINUOUS COLADOR TECHNICAL FIELD This invention relates to valves used in the continuous casting of metal, especially steel. In particular, it relates to inert gas supply systems to the matching surfaces of slide gate valves and plug flow control valves or systems to create a seal by generating a positive gas pressure between the mating surfaces to inhibit the entry of environmental gases, such as air, that could degrade the quality of the metal being cast and to help minimize the entry of molten metal to the surrounding surface. The invention includes the use of a porous refractory insert in a channel around or partially around the valve opening, occupying only part of the channel so that the gas can be evenly distributed in the circumferential void behind (upstream of) the porous refractory insert. . The porous refractory insert evenly distributes the inert gas flow between the contact surfaces which are moved in contact with each other such as the contact surfaces of the slide plate and the tube holder and / or the slide plate and the top plate, the tube holder and the nozzle, and other similar abutting surfaces that slide or move relative to one another. A similar structure is used to prevent the ingress of air and other gases such as sealing gas into contact with molten metal at the top of a pouring tube where it is attached to a pipe holder. The invention is useful in any substantially flat abutting surface, made up of movable or stationary parts, which forms a conduit for the liquid metal near the inlet of a continuous strainer.

BACKGROUND OF THE INVENTION In the continuous casting of metals, and of steel in particular, the molten metal is drained from a cauldron or perol through a valve, commonly a slidable valve, through a refractory nozzle and into the tube that is partially immersed in the continuous incipient ingot to isolate molten steel from air and other gases. The tube is fixed to a tube holder that makes contact with the underside of a slide valve. The present invention relates to the control of the entry of undesirable gases (the aspiration of air) through the joint between the tube and the tube holder, and also through the substantially flat abutting surfaces of the slide valves. Sliding gate valves and shutter bar valves with an in-line dump tube exchange capacity have been quite practical and have been widely used. However, there is still room for an improvement in the control of gas filtration through the coupling surfaces of the valve. Said slide valves and shut-off valve valves operate obviously under difficult conditions; they are put in direct contact with the molten metal that has a tendency to splash and freeze. By having movable components, they are subjected to some wear and tear, and since they comprise two or more joints of wide surface areas, gases, such as air are prone to find cracks and crevices through the surfaces adjoining the flowing metal , where pressures are almost always lower than environmental pressures outside the unit; said gases can cause unwanted reactions in the molten steel. Prior to the present invention, the joint between the tube holder and the tube itself was simply covered with mortar. A shield or steel hoop is often used to cover the gasket, but such a shield is generally more effective in reinforcing the structure than in providing a seal against gas. Cracks in the mortar inevitably develop, and the joint with mortar and shroud often allows negative pressures inside the pipe to cause air to be sucked through the joint. A major problem caused by air is the oxidation of the aluminum present in the steel. The formation of alumina at this stage of steel production is highly undesirable. In the patent of E.U.A No. 3, 887,117, Fehling describes a U-shaped channel that is placed in the sliding part or the complementary stationary part of the valve. The U-shaped channel is placed inside the refractory insert of the unit and the inert gas is fed to it from an external source. The inert gas provides a positive pressure with respect to the atmosphere outside the valve. This type of structure is subject to the possibility that the molten metal reaches the channel and blocks the passage of the gas. Russo, in the patent of E.U.A. No. 5,100,034, it is proposed to overcome Fehling by inserting a porous refractory material into a similar channel. However, Russo's patent feeds the gas only to a portion of the refractory insert, thus requiring the gas to pass through the refractory insert before entering an open space, leading to cracks that will be sealed. This configuration leads to a considerable variation in the gas pressure in different areas of the unit; likewise, the refractory insert can not physically block the molten metal spill into the channel. In the patent of E.U.A. No. 4,576,317, Wenger describes an improvement to the '117 Fehling concept, providing a second U-shaped channel in the complementary sliding surface, dimensioned so that the channels overlap in certain positions. A vacuum is created over the channels. It should be kept in mind when considering the construction of devices to feed inert gas to the contact surfaces in slide gate valves, which is generally more convenient to feed the gas through the stationary portions of the valve than through the sliding mobile; however, the present invention is not so limited.

BRIEF DESCRIPTION OF THE INVENTION The present invention employs a particular assembly for feeding inert gas into the joint between the mating surfaces of the tube and the tube holder. Inside the mating surface of the tube holder, a circumferential channel is used in which a porous refractory element is placed without occupying the full depth of the channel, thereby providing a circumferential feed passage for the introduction of gas to a more or less equal pressure, which makes contact with the porous refractory insert along the channel. The inert sealing gas is fed from outside the shell, through the wall of the pipe holder, preferably in response to a signal representing the difference in pressure between the circumferential feed passage and the external environmental pressure.

The inert sealing gas is thus able to displace the air that can enter the joint. No mortar is used here on the complete coupling surfaces of the joint, as has commonly been the case in the past. Instead, a preferred gasket is designed to provide a mortar shelf on the inner surface of the tube and a complementary projection on the inner surface of the tube holder; the ledge and the projection are kept approximately one to six millimeters apart when the remaining flat surfaces of the joint are placed together, thus providing space for a circumferentially mortar area. At the inner end of the shelf, the tube is cut circumferentially at an upward angle so that the mortar does not tend to be splashed towards the rest of the joint; to ensure that this does not happen, a relief slot is used at the upper end of the circumferential cut angled upwards. The purpose of the relief groove in the mortar variation of this invention is to minimize the possibility of mortar and / or steel being introduced into the main joint. Furthermore, this preferred assembly requires that the flat portions of the coupling surfaces of the joint be flat, ie with a tolerance of .00125 cm to .03 cm -that is, that the surface preferably does not vary more than about .03 cm to throughout its area. If the circumferential porous refractory insert projects beyond the flat surface of the joint, it must also be fabricated to perform a firm, even contact around the surface of the main portion of the joint. In this way, the invention comprises a circumferential porous refractory insert placed on the surface of the pipe holder gasket, separated from the inner wall of the tube holder and its outer wall and being in contact with a gas supply channel to along its circumference. The gas supply channel is in turn connected to an inert gas source, preferably powered in response to a signal that is a function of the difference between the external ambient pressure and the pressure in the inner wall of the tube and / or the circumferential passage of gas supply. This invention includes an apparatus and method for feeding inert gas to the adjoining surface of a moving member and stationary members of a gate valve such as that used to control the casting of molten steel in a continuous strainer. In the case of the obturator bar valve, the movable member is the submerged tube holder or nozzle, and the stationary member is the nozzle of the cauldron or an intermediate plate, depending on the particular structure. A preferred form of the invention includes the use of one channel, preferably U-shaped, on the surface of the slidable valve, and another channel, also preferably U-shaped generally, on the coupling surface of at least one of the Stationary portions of the valve. Each of the channels is partially filled with a porous refractory insert, such that the outer surface of the refractory insert is flush with the respective engaging surface, leaving an unoccupied area of the deepest channel within the sliding or stationary portion, so that an open area or passage over the entire inner surface is provided. of the porous refractory insert. This open area or passage in the channel is connected to a duct for a source of inert gas, which is then provided at pressures that are equal on the entire inner surface of the porous refractory insert. To transport gas from one element to another, that is, from the stationary portion of the valve to the slide plate, open channels are provided in position so that, when juxtaposed, the gas can pass freely from one to the other.

DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevational view of the upper region of a typical commercial prior art continuous steel strainer, showing the placement of the commonly used sliding gate valve. Figures 2, 3, 4, 5 and 6 are directed to this type of valve. Figures Ib and lc show sealing rod arrangements of the prior art to which this invention is also applicable. Figure 2 is a simplified side sectional view of a slide gate valve showing the top plate, slide plate and tube holder, together with a preferred configuration of the present gas supply system. Figure 3a is a simplified top view of the upper surface of the tube holder, showing only the characteristics of the upper surface. Figure 3b is a simplified view of the underside of the slidable plate, showing only the characteristics of the surface. This lower side of the sliding plate will slide on the surface of the tube holder of figure 3a. Figures 3c, 3d and 3e show the relationship of the characteristics of figures 3a and 3b as the sliding plate is moved to the left towards the "fully closed" or "inlet" position (3c), the "disminuting" position or of work (3d) and the position of "exit" (3e). Figure 4a is a simplified top view of the top plate, showing only the characteristics of the bottom side. Figure 4b is a simplified top view of the upper part of the sliding plate, showing only the relevant features to the upper surface.

Figures 4c, 4d and 4e show the relationship of the characteristics of figures 4a and 4b as the sliding plate is moved to the left towards the "fully closed" or "inlet" position (4c), the "disminuting" position or of work (4d) and the position of "exit" (4e). Figures 5 and 6 show the variation of the slide plate incorporating this invention. Figure 7a is an elongated side sectional view (compared to Figure 1) of a typical prior art gasket between a drain tube and a tube holder. Figure 7b is a much more elongated detail of another variation of the prior art of the joint, showing mortar on the outside of the tube. Figure 8 is a side sectional view of a drainage tube and a tube holder gasket of this invention, showing the circumferential porous refractory insert and the circumferential gas feed passage. Figure 8b illustrates the sealed adaptation of the porous refractory insert in the circumferential channel. Figure 9a is a side sectional view of a different embodiment of this invention, including a mortar shelf and a mortar relief groove. Figure 9b shows the preferred end of the mortar placement in the joint. Figure 10 illustrates that this invention can be used without mortar in the joint.

Referring now to FIG. 1, this more or less conventional assembly includes a copper 2 having a refractory liner 1 containing liquid steel 3 to form a continuous jacket. The control of the flow of steel through the refractory nozzle 4 (which is ensured by the flow block 20) is by means of a sliding gate valve comprising an upper plate 5 and the sliding plate 6 as is known in the art. . The upper plate 5 can be secured to the mounting plate 51. Directly below the sliding plate 6 is the tube holder 7 and fixed directly below it is the drain tube 8. During operation, the drain tube 8 passes directly through the slag layer 9 on top of the incipient shawl 11, which is formed of molten steel 10 deposited near the top of the incipient shad 11 and being exposed to the smallest possible atmosphere. The copper mold cooled with water 12 solidifies the steel sufficiently so that by the time it leaves the mold 12 at its bottom, a hard shell 13 has been formed strong enough to contain the still molten steel 10 at its center. The copper mold 12 is reinforced by a steel casing 14 around it. The flow rate of the molten steel 3 through the sliding plate 6 is controlled to simultaneously (1) prevent an overflow of the mold 2 (2) maintain a constant level of molten metal and (3) comply with the solidification and of production of the scabbard 11. FIG. Ib illustrates a variation of the prior art to which the present invention is also applicable. In this variation, the submerged entry nozzle 47 passes through the slag layer 9 as in FIG. 1, but there is no sliding plate 6 (FIG.; instead, the flow of metal is stopped by the insert, by means of the manipulator 45, of the plug 44 in the refractory nozzle 4. The refractory nozzle 4 can be surrounded by mortar 54. The submerged inlet nozzle 47 can then be replaced by moving it horizontally, maintaining contact with the fixed plate 46 on the abutting surface 48, which retains the molten metal in the passage 52. A new submerged inlet nozzle 47 is located horizontally, also maintaining contact with the fixed plate 46 on the surface adjacent 48. As will be seen later, the movement of the submerged entry nozzle 47 through the abutting surface 48 is exactly comparable, for these purposes, with the movement of the upper surface of the slide plate 6 with respect to the underside of the top plate 5 as illustrated in Figures 4a-4e. That is, the gas supply system of Figures 4a-4e can be applied exactly in the variation of Figure Ib. In Figure 1c, another variation is shown in which the refractory nozzle 4 is combined with the shell of the copper 2 to form an integral top plate / nozzle 50 which forms an abutting surface 49 directly with the tube holder 53. The tube holder 53 can be replaced in a manner similar to the replacement of the submerged entry nozzle 47 in Fig. Ib - that is, it is moved horizontally, keeping it in contact with the nozzle / upper plate 50 on the adjoining surface 49 while the shutter 44 stops the metal flow. Again, the upper surface of the tube holder 53 may be comparable with the upper surface of the sliding plate 6 as illustrated in FIGS. 4a-4e, and the lower surface of the nozzle / upper plate 50; both can be equipped with a gas supply system exactly as described in Figures 4a-4e. In figure 2, it is observed that the upper plate 5 has a hole 15 and a gas supply channel 16, whose lower part is filled with a porous refractory insert 17, leaving a passage 18 that connects with a gas pipe 19 that it is in turn connected to a source of inert gas, not shown, under pressure. Sliding plate 6 has a hole 31 and gas supply channels 21 and 22 similar to gas supply channel 26, also partially filled with refractory shapes 23 and 24, forming passages 25 and 26. The upper part of the tube holder 7 also has a gas supply channel 27 partially filled with refractory insert 28 and forming a passage 29. The passage 29 is connected to the gas supply duct 30 in a manner similar to that of passage 18 and duct 19 on the plate 5. Those skilled in the art can recognize that the introduction of gas through the ducts 19 and 30 is contemplated in this embodiment only in the stationary portions, the top plate 5 and the tube holder 7. However, it is not It is necessary in principle that the introduction of gas should only take place through a stationary part; instead, it can be glimpsed, for example, through the use of flexible tubing and the like, that the introduction may be in the sliding plate 6, as illustrated in Figure 6. The porous refractory insert 1 used for the insert The channel can be any porous refractory insert known in the art, such as refractory inserts of porous zirconia or porous refractory inserts with high alumina content. In practice, typically ranging from 6.35 mm in thickness to 19.05 mm in thickness, they should provide a pressure drop preferably not greater than about 0.14 kg / cm2 (and in any case not greater than about 0.84 kg / cm2 pressure drop) when a normal inert gas such as argon is flowing through the insert at approximately 34.75 square meters per hour. The refractory insert can be formed in the channel or prefabricated and placed in the channel with a suitable sealant for pressure, temperature and wear conditions; said sealants are known in the art. The series of figures 3a-3e are specifically described with respect to the configurations of figures la and 2, although, as will be apparent, in principle they are equally appropriate for the configurations of figures Ib and lc. Figure 3a is a simplified top view of the upper surface of the tube holder 7, defining a hole 32 within the refractory insert 34 and showing the gas supply channel 27 and the gas transfer channel 35. It can be seen that the Gas supply channel 27 may have a U-shape generally, as preferred. The refractory insert 28, seen in Figure 2 partially filling the gas supply channel 27, is not illustrated in Figure 3. The duct 30 connects to the gas transfer channel 35 and the gas supply channel 27, and receives gas from an external source not shown. The sliding plate 6 in FIG. 3b is viewed from above in a simplified form showing only features directly relevant to its bottom surface that will abut the tube holder 7. The slide plate 6 has a gas transfer channel 36 and a channel of gas supply 22 on its lower surface. The gas transfer channel 36 is connected to the gas supply channel 22 via the pipeline 33. As will be seen in Figures 3c, 3d and 3e, the dimensions of the gas transfer channel 36 are in accordance with the dimensions of the gas channel. transferring gas 35 onto the tube holder 7 (figure 3a) so that a connection can be made in which the gas originating in the pipeline 33 passes (figure 3a) and is passed to the gas transfer channel 35 of the holder of tube 7 to the gas transfer channel 36 of the sliding plate 6. This is illustrated in more detail in figures 3c, 3d and 3e. In Figure 3c, the characteristics of Figure 3b have been juxtaposed over those of Figure 3a to illustrate the relative positions of the gas supply channel 27 and gas transfer channel 35 of the tube holder 7 with respect to the supply channel of gas 22 and the gas transfer channel 36 of the sliding plate 6. Figure 3c is the first of the series 3c, 3d and 3e showing the typical movement of the sliding plate 6 on the tube holder 7. As illustrated , the sliding plate 6 moves from right to left. When they reach the "inlet" or "fully closed" position in Figure C, meaning that there is no longer an overlap of the hole 31 and the hole 32, the gas transfer channels 35 and 36 have begun to overlap, allowing the Inert gas travel from duct 36 through gas transfer channels 35 and 36 to duct 33 and beyond to gas supply channel 22 of slide plate 6, while the gas continues to fill the supply channel of gas 27 in the pipe joint 7. The reader can observe that the passages 26 and 29 and the refractory inserts 24 and 28 in figure 3 are not shown for reasons of simplicity; The gas flow mentioned in the gas supply channel 22 and 27 is limited to passages 26 and 29. It can be seen that the gas transfer channels 35 and 36 are removed in some way from the holes 31 and 32. This is it prefers because the gas transfer channels 35 and 36 do not contain porous refractory inserts as do the channels of their gas inietro 22 and 27; the placement of the molten metal, apart from being practical, is recommended to minimize the incidence of metal deposition. In addition, the gas transfer channels are aligned linearly with the sliding direction of the coupling surfaces. This preferred form of abutting surface further minimizes the possibility of deposition in these channels. Figure 3d shows the sliding plate 6 having been moved further to the left on the tube holder 7 than that shown in figure 3c, eg, towards the "disminuting" position, or towards a position for operation normal or typical in which the holes 31 and 32 are overlapping but not concentric. Here there is more than one overlap of the gas transfer channels 35 and 36 as seen in Figure 3c. Typically, the gas flow will be maintained at a high velocity in this position to overcome the negative gas pressure induced by the metal flow through the holes 31 and 32. Upon completion of operation, the slide plate 6 typically moves further. to the left (as illustrated), at least to the "exit" position of Figure 3e, where it will be seen that the holes 31 and 32 no longer overlap, and the flow of the liquid steel 3 stops. The gas transfer channels 35 and 36 can still overlap as shown, but the gas flow will be suspended at the discretion of the operator. As previously mentioned with respect to Figures 3a-3c, the series 4a-4e is specifically described for the configuration of Figure 1, but the operation principle is applicable to the "quick tube change" structures of Figures 1b. and lc. In Figure 4a, a simplified top view shows the top plate 5 having a gas supply channel 16 generally U-shaped on its bottom surface around the orifice 15. The gas supply channel 16 is connected to the transfer channel of gas 37 through duct 40. Gas supply channel 16 is fed with inert gae that comes from duct 39 from an external source not shown. As with the gas supply channels 27 and 22 of Figures 3a and 3b, the porous refractory inserts (illustrated in Figure 2 - see refractory inserts 17, 23, 24 and 28) are present, but are not illustrated in Figure 4 to give simplicity to the drawing. The gas flows from the duct 39 into the passage 18 of the gas supply channel 16 (which contains the refractory insert 17 -see Figure 2) and thence through the duct 40 to the gas transfer channel 37, which does not contain porous refractory insert. The upper surface of the slide plate 6 is illustrated in Figure 4b, showing a gas supply channel 21 connected to a gas transference channel 38 through the duct 41. In the "fully closed" or "inlet" position. of Figure 4c, the sliding plate 6 has been moved to the left (as illustrated and corresponds to Figure 3c), but the hole 31 still does not overlap the hole 15 of the upper plate 5. However, it has been communication is established between the gas transfer channels 37 and 38 due to their overlapping positions, whereby the gas can flow from the upper plate 5 to the gas supply channel 21 of the sliding plate 6. In Figure 4d, in the "disminuting" position, the metal can flow through the holes 31 and 15; the inert gas flowing into the gas supply channels 16 and 21 and through the porous refractory inserts 17 and 23 (see Figure 2) provides a positive pressure on the abutting surface of the top plate 5 and the slide plate 6, while a similar effect takes place on the adjoining surface of the sliding plate 6 and the tube holder 7, as shown in figure 3d (see also the refractory inserts 24 and 28 in figure 2). The positive inert gas pressure prevents air and other environmental gases from entering the orifice 32 of the tube holder, where they could damage relatively reactive molten steel.

Figure 4e shows the "output" relationship of the gas supply channels 16 and 21 and of the gas transport channels 37 and 38 as the slide plate 6 is moved to the left at the conclusion of the operation. The juxtaposition of the upper plate 5 and the sliding plate 6 shown in figures 4c, 4d and 4e can be seen as superimposed on the corresponding juxtaposition of the sliding plate 6 on the tube 7 illustrated in figures 3e, 3d and 3e. This invention includes the slide plate shown in perspective in Figure 5, which shows the gas transfer channels 21 and 22, the refractory insert 23 and the gas transfer channels 36 and 38. This embodiment shows an internal duct 42 in the form of H allowing the gas flow from any of the gas transfer channels 36 or 38 to both gas supply channels 21 and 22. The pipe 42 can be replaced by a simple pipe connecting to the gas transfer channel 38 with the gas supply pipe 21 and / or a simple pipeline connecting the gas transfer channel 36 to the gas supply channel 22. In other words, for any reason, separate gas supply systems may be available on the gas supply channel. the top and bottom of the sliding plate. This invention includes such embodiments, provided that a refractory insert 23 or 24 is present. In Figure 6 a variation of the slide plate 6 is shown which does not have gas transfer channels because it has its own gas supply system represented by the T-shaped duct 43 serving to supply inert gas from an external source not shown to the passages 25 and 26 of the gas supply channels 21 and 22. Figure 7a shows a conventional gasket 60 of a pipe holder 7 and a drain tube 8. These are joined by a layer of mortar 61 and enclosed by a steel shell 62. The mortar tends to develop cracks and otherwise allow the passage of gases into the interior 63 of the tube, and the shell 62 is not typically made to be gas tight; consequently, the gases can easily pass under these and enter the joint 60. In figure 7b there is shown a variation in which the mortar 61 extends only partially towards the joint 60, but it is also used on the exterior of the tube 8. This variation also illustrates the commonly used ring 78 surrounding the entire tube 8 and the welding strip 79 which serves as a seal between the ring 78 and the shell 62. Typically, the close contact between the ring 78 and the The tube 8 is secured by keeping the ring 78 under compression while the solder strip 79 is secured. Figure 8a shows an embodiment of this invention, in which the circumferential channel 64 is made in the tube holder 7 and partially filled to along its circumferential shape with a porous refractory insert 65, leaving a circumferential gas passage 66. The circumferential gas passage 66 is connected through at least one duct 67 to a source 6. 8 of inert gas such as argon or other suitable gas. The gas flow within the gas passage 66 from the source 68 is controlled in a manner known as a function of the difference between the gas pressure in the gas passage 66, measured by the pressure transducer 69, and the ambient pressure Exterior. The pressure difference is generally from about 0.14 kg / cm2 to about 0.35 kg / cm2, and is preferably maintained at at least about 0.21 kg / cm2 to provide a pressure barrier at the joint - that is, between the coupling surfaces 73 and 74-- against environmental gae; the pressure drop in the duct 67 will vary depending on its length and internal diameter, but it can be expected to be less than 0.035 kg / cm2 and more desirably about 0.014 kg / cm2. The mortar 70 fills the space between the circumferential shoulder 71 on the tube of 8 and the complementary circumferential rib 72 over the tube holder 8. The engaging surface 73 of the tube holder 7 and the engaging surface 74 of the pour tube 8 are preferably flattened within a tolerance of 0.000125 cm to 0.03 cm. Figure 8b provides detail of particularly the sealant 77 between the porous refractory insert 65 and the channel 64. The sealant must be a sealant resistant to high temperatures and serves to prevent passage of the gas from the circumferential gas passage 66 to the joint below of the coupling surface 73 without passing through the refractory insert 65. A preferred variation of this invention is shown in Figure 9a. In this version, it is noted that a circumferential shelf 75 is formed on the upper part of the emptying tube 8 and that a complementary projection 75 is formed on the lower end of the tube holder 7. Behind the projection 76 - that is, concentrically external from the same, a mortar relief groove 77 is provided in the form of a deeper cavity to allow the splash of mortar 70 during the placement of the tube holder 7 on the tube 8. The circumferential channel 64 containing the porous refractory insert 65 is similar to that of Figures 8a and 8b, and is also connected through the circumferential gas passage 66 and the duct 67 to the gas source 68. As in the embodiment of Figure 8, the flow of inert gas towards the channel 64 can be controlled as a function of the pressure in the gas passage 66 and the external environmental pressures determined by the transducer 69. In any case, the effect of the gas passage open cunferencial 66 is to provide a substantially uniform gas feed pressure around the circumferential channel 64. Preferably, care is taken during the placement of the mortar not to have an excess of mortar that could reach the horizontal portion of the joint (surface coupling 74). This is illustrated in more detail in Figure 9b, in which it will be noted that the mortar 70 has been carefully placed so that it does not extend over the horizontal area of the coupling surface 74 by joining the coupling surfaces 73 and 74 of the pipe holder 7. and the drain tube 8. In Figure 10, the tube holder 7 and the drain tube 8 form a mortarless joint on the mating surfaces 73 and 74 which have been flattened to a tolerance of <0.03 cm. The channel 64 is formed in the tube holder 7 as in the other figures and partially filled with a porous refractory insert 65, leaving a circumferential gas passage 66 available to conduct gas from the duct 67 with an even pressure on the surface upper part of the refractory porous insert 65, thus ensuring its uniform distribution. Also in this configuration, an optional center ring 80 surrounds and reinforces the assembly, and the metal band 81 is also tightly fixed to the circumference of the upper portion of the tube 8. To prevent the ingress of ambient gas such as air from the outside of the assembly through the joint, an inert gas such as argon is fed to the gas passage 66 from the source 68 at such a rate as to maintain a pressure difference between the external ambient pressure and the pressure in the channel 64 of at least 0.21 kg / cm2. Those skilled in the art will find that this invention minimizes the possibility of seal destruction between mating surfaces 73 and 74 caused by the migration of mortar pieces. Of the same. In this manner, this invention tends to ensure that if any gae enters the interior 63 through the joint 60 (between the mating surfaces 73 and 74 and through the mortar 70), it is much more certain that it is the gas coming from the source 68 that the external air that may have leaked to the seal 60 from behind the shell 62. The distribution of the inert gas around the gas passage 66 ensures that an inert gas with sufficient pressure will be available to any point on the circumference of the insert. refractory porous 65. The porous refractory material used for channel inserts can be any of the refractory inserts known in the art, such as porous refractory inserts of porous zirconia or porous refractory inserts with a high alumina content. In practice, typically varying from 6.35 mm in thickness to 19.05 mm in thickness, they should provide a pressure drop preferably not greater than about 0.14 kg / cm2 (and in any case no greater than about 0.84 kg / cm2 pressure drop) when a normal inert gas such as argon is flowing through the ineert at approximately 34.75 square meter per hour. The refractory insert can be formed in the channel or prefabricated and placed in the channel with a sealant as illustrated in Figure 8b. In this manner, the present invention includes a sliding plate adapted to supply inert gas as described, a slide gate valve having gas supply sevens as described, and an apparatus for supplying molten steel to the top of a strainer. continuous including a boiler and a flow direction means beneath it, each of the boiler and the flow direction means having substantially planar surfaces forming an abutting surface in at least one of which a supply channel is constructed of gas that includes a porous refractory insert extending along its length and having a depth extending from said substantially flat surface to partially fill said channel (preferably about half the depth of the channel, or approximately one quarter to approximately three quarters deep); when the gae supply channels are on both surfaces, the surfaces may also have gas transfer channels for supplying gae from a source on, or near a surface to a passage in a channel on the other surface.

Claims (6)

NOVELTY OF THE INVENTION CLAIMS

1. - A molten metal supply apparatus for a continuous strainer, said molten metal supply apparatus having a molten metal upper conducting element comprising a tube holder and a lower molten metal conducting element comprising a tube, said The upper molten metal conducting element and said lower molten metal conducting element each have an opening therethrough to guide the substantially descending flow of molten metal, each said molten metal conducting element having a substantially flat surface which adjoins the other to form an adjoining surface; wherein the flow of metal in said elements tends to create a negative pressure that eats through said abutting surface, further characterized in that said substantially flat surface of at least one of said molten metal conducting elements has a supply channel of gae for supplying inert gas to said adjoining surface, said gas supply channel being partially filled, on the side of said channel closest to said subetanal surface being flat, with a porous refractory insert; said substantially flat surfaces of both conducting elements of molten metal having been polished to a flatness with a tolerance of 0.03 centimeters.

2. An apparatus according to claim 1, wherein both of said molten metal conductive elements contain gas supply channels partially filled with a porous refractory insert.

3. An apparatus according to claim 1, wherein the upper part of said upper molten metal conducting element has a circumferential ledge extending toward the opening to guide the downward flow of molten metal through the molten metal. same, and said lower molten metal conducting member has a complementary projection with a mortise deepening groove in the form of a deeper recess, and the mortar between said circumferential ledge and said complementary projection that does not extend towards the area between the recesses. substantially planar surfaces of the upper and lower conducting elements of molten metal.

4. A sliding gate valve for a continuous strainer, comprising a stationary element and a slidable plate, each of said stationary element and said slidable plate having a hole therethrough for conducting flowing metal and a working surface in contact with each other, each of said work surfaces has gas supply channels therein for conducting inert gas, each of said gas supply channels being partially filled with inerartee porous refractories in a substantially uniform manner with said surfaces of work, defining at the same time a gae passage into said refractory insert, each of said working surfaces includes a gas transfer channel that does not have a porous refractory insert therein to conduct gas from a transfer channel of gas to the other, said gas transmission channels are provided and dimensioned so that when said Holes are aligned, said gas supply channels are connected to said gae traneference channels and the gas can pass from one gas transfer channel to another.

5. An apparatus according to claim 4, wherein said gas transfer channels extend longitudinally in the direction of sliding movement of said slidable plate, and further comprising a duct connected to said gas supply channels. already said gae transfer channel, and a source to supply inert gas to said pipeline, supply and transfer channels. 6.- A tube assembly for use in continuous metal casting, comprising (a) an elongated and generally cylindrical drainage tube having an axial opening therethrough, said draining tube being oriented generally vertically and having a generally flat upper end, (b) a tube holder that it has an axial opening therethrough, said tube holder being fixed on the euperior part of said tube, and has a generally flat lower end adapted to engage said euperior end of said emptying tube, and having a circumferential channel in said flat lower end, (c) gas supply means connecting said circumferential channel with an inert gae source, (d) a porous refractory core partially filling said circumferential channel through the circumference, leaving said circumferential channel partially open along the circumference and connection to said gas supply means, whereby a feed passage is formed of gas for providing a uniformly uniform feed gas pressure around said circumferential channel in contact with said porous refractory insert, and (e) means for feeding inert gas from said source of inert gas to said circumferential channel and for controlling the flow of gas. Inert as a function of the difference between the pressure in said circumferential channel and the environmental pressure outside said pipe assembly, said flow of inert gas being controlled to maintain said pressure difference within a scale of 0.14 to 0.35 kg / cm2.