Claims:1. An apparatus (100) to facilitate flow of molten metal stream, the apparatus (100) comprising:
a conduit (16) comprising an inlet (17) and an outlet (18), the conduit (16) is configured to conceal at least a portion of the molten metal stream; and
at least one shroud (50) mounted on at least one of the inlet (17) and the outlet (18) of the conduit (16), the at least one shroud (50) comprising:
a first channel (51) and a second channel (52) arranged concentric to one another forming an annular gap (45) in between, wherein a first end (45a) of the annular gap (45) is closed and at least a portion of second end (45b) is configured as a passage;
at least one inlet port (20) extending from the first channel (51) to the annular gap (45), the at least one inlet port (20) is connectable to an inert gas (22) source to receive inert gas; and
a plurality of baffles (11) provisioned in the annular gap (45), the plurality of baffles (11) are configured to direct flow of the inert gas towards the second end (45b) of the annular gap (45) to discharge the inert gas around the molten metal stream.

2. The apparatus (100) as claimed in claim 1, wherein the inlet (17) of the conduit (16) is configured to receive molten metal from a vessel, and an outlet (18) of the conduit (16) is configured to discharge the molten metal to a mould in a continuous casting process.

3. The apparatus (100) as claimed in claim 2, wherein the conduit (16) is positioned with a predetermined gap between the outlet of the vessel and the inlet of the mould.

4. The apparatus (100) as claimed in claim 3, wherein the at least one shroud (50) is configured to direct the inert gas from the inert gas source (22) to the predetermined gap between the conduit (16), and at least one of the outlet of the vessel and the inlet of the mould.

5. The apparatus (100) as claimed in claim 1, wherein the plurality of baffles (11) are configured on at least one of outer circumference of the second wall (52) and an inner circumference of the first wall (51).
6. The apparatus (100) as claimed in claim 1, wherein each of the plurality of baffles (11) comprises of a first element (11a) and a second element (11b).

7. The apparatus (100) as claimed in claim 6, wherein the first element (11a) is substantially at obtuse angle to the second element (11b).

8. The apparatus (100) as claimed in claim 7, wherein the angle between the first element (11a) and the second element (11b) ranges from 110 degrees to 150 degrees.

9. The apparatus (100) as claimed in claim 1, wherein the at least one inlet port (20) directs the inert gas tangentially in the annular gap (45).

10. The apparatus (100) as claimed in claim 1, wherein the plurality of baffles (11) divert the flow of inert gas from tangential direction to vertical direction towards the second end (45b) of the annular gap (45).

11. The apparatus (100) as claimed in claim 1, wherein the at least one shroud (50) comprises a tapered portion (14) proximal to the inlet port (20) to direct the flow of inert gas towards the plurality of baffles (11).

12. The apparatus (100) as claimed in claim 1, wherein the first channel (51) and the second channel (52) are flared (12) at the second end (45b) of the annular gap (45) to accelerate the discharge of the inert gas around the molten metal stream.

13. The apparatus (100) as claimed in claim 1 comprises at least one valve (24) in an inert gas flow line for regulating flow rate of the inert gas into the annular gap (45) of the shroud (50).

14. The apparatus (100) as claimed in claim 1, wherein the molten metal is liquid steel.

15. A shroud (50) for discharging inert gas around molten metal stream flowing from a tundish to a mould in a continuous casting process, the shroud (50) comprising:
a first channel (51) and a second channel (52) arranged concentric to one another forming an annular gap (45) in between, wherein a first end (45a) of the annular gap is closed and at least a portion of second end (45b) is configured as a passage;
at least one inlet port (20) extending from the first channel (51) to the annular gap (45), the at least one inlet port (20) is connectable to an inert gas source (22) to receive inert gas; and
a plurality of baffles (11) configured in the annular gap (45), the plurality of baffles (11) are configured to direct flow of inert gas towards the second end (45b) of the annular gap (45) to discharge the inert gas around the molten metal stream.

16. The shroud (50) as claimed in claim 15, wherein the first channel (51) and the second channel (52) are concentric cylinders.

17. The shroud (50) as claimed in claim 16, wherein the first channel (51) and the second channel (52) are joined together at the first end (45a) of the annular gap (45).

18. The shroud (50) as claimed in claim 17, wherein diameter of the concentric cylinders at the first end (45a) of the annular gap (45) is greater than diameter of the concentric cylinders at the second end (45b) of the annular gap (45).

19. The shroud (50) as claimed in claim 15 comprises a tapered portion (14) proximal to the inlet port (20) to direct the flow of inert gas towards the plurality of baffles (11).

20. The shroud (50) as claimed in claim 15, wherein the first channel (51) and the second channel (52) are flared (12) at the second end (45b) of the annular gap (45) to accelerate the discharge of the inert gas around the molten metal stream.
, Description:TECHNICAL FIELD
The present disclosure generally relates to Manufacturing Technology. Particularly, but not exclusively, the present disclosure relates to a casting process. Further, embodiments of the disclosure disclose an apparatus to facilitate flow of molten metal stream and to protect the stream from contact with surroundings during continuous casting process.

BACKGROUND
In manufacturing technology, most of the components are manufactured using various primary manufacturing processes. Some of the components find applications in different sectors, including but not limiting to automotive industries, consumer products, light and heavy duty machineries. Such components are produced in large volumes by processes including but not limited to gravity casting, pressure die-casting and continuous casting processes. In such mass production techniques involving one or more types of casting processes, metals or metallic alloys are heated to temperatures substantially higher than liquidus temperature (just above the melting point). Thereafter the molten metal is poured into mould with or without cavity. The molten metal accumulated in the mould is allowed to cool down to solidus temperature so that it takes the contour (or shape) of the mould, finally forming the solidified mass of desired shape. An important requirement during the casting process is careful transfer of molten metal from furnace to the mould.

Conventionally, various methods are employed to transfer molten metal from furnace or intermediate vessel to the casting mould. Commonly, there are two modes by which transfer of molten metal takes place during casting viz. an open casting process and a closed casting process. In open casting, molten metal which is stored in a storage unit (alternatively referred to as intermediate vessel) is directly allowed to enter the mould in the form of molten metal stream. Open casting process provides sufficient visibility and allows the operator to monitor the flow of molten metal between the storage unit and the mould. However, in open casting process, air present around the exposed molten metal stream contaminates the molten metal by oxidation and re-oxidation. On the other hand, the lubrication oil which is generally added to the molten metal to prevent sticking of the molten metal with surfaces of mould undergoes combustion at high temperatures, emitting fumes. The fumes so emitted contain hydrocarbon gases causing potential hazards to operators’ health. To expel fumes emanating from burning lubricating oil, streams of air are circulated across the molten metal stream, so that the air streams divert fumes emanating from the burning oil and prevent the fumes from reaching the operators. However, continuous circulation of air stream all around the molten metal stream increases consumption of energy. In addition, the circulation of air stream around molten metal stream results in oxidation of molten metal, thereby reducing its internal cleanliness.

On the other hand, closed casting process is a type of casting where molten metal stream is passed through a conveyor, typically a conduit connected between outlet of the storage unit and inlet of the mould, so that entire length of flow of the molten metal stream is protected by walls or surfaces of the conveyor. The presence of conveyor also ensures that molten metal stream is not subjected to oxidation during its flow. However, this arrangement has one or more limitations, such as limited or lack of visibility of molten metal stream, limited refractory life of the conveyor which rises a need for frequent replacement of conveyor, cracking of walls of the conveyor under thermal stresses which may cause molten metal stream to come in contact with atmospheric air, and entrainment or entrapment of eroded particles within molten metal stream during the flow of molten metal stream at high temperature. The inclusion of eroded particles into the molten metal stream will result in casting defects which reduces quality of the cast products. Also, lack of visibility of molten metal stream in closed casting process does not provide any indication of choking or blocking of molten metal stream in the flow path (particularly at exit side and entry side of nozzles) to the operators. The operator, therefore, cannot monitor flow of molten metal stream through the conveyor, and any potential accumulation at a particular location inside the conduit may result in choking or blockage of the conduit.

In light of foregoing discussion, there is a need to develop an improved apparatus which facilitates smooth transfer of molten metal between the storage unit and mould during casting process, to overcome one or more limitations stated above.

SUMMARY OF THE DISCLOSURE
One or more drawbacks of conventional apparatus and methods used to transfer molten metal during casting processes as described in the prior art are overcome, and additional advantages are provided through the apparatus as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.

In a non-limiting embodiment of the present disclosure, there is provided an apparatus to facilitate flow of molten metal stream, the apparatus comprising a conduit with an inlet and an outlet. The conduit is configured to conceal at least a portion of the molten metal stream. At least one shroud is mounted on at least one of the inlet and the outlet of the conduit. The at least one shroud comprises a first channel and a second channel which are arranged concentric to one another forming an annular gap in between. A first end of the annular gap is closed and at least a portion of second end is configured as a passage. The shroud also comprises at least one inlet port extending from the first channel to the annular gap. The at least one inlet port is connectable to an inert gas source to receive inert gas. A plurality of baffles is provisioned in the annular gap. The plurality of baffles is configured to direct flow of the inert gas towards the second end of the annular gap to discharge the inert gas around the molten metal stream.

In an embodiment of the present disclosure, the inlet of the conduit is configured to receive molten metal from a vessel, and an outlet of the conduit is configured to discharge the molten metal to a mould in a continuous casting process.

In an embodiment of the present disclosure, the conduit is positioned with a predetermined gap between the outlet of the vessel and the inlet of the mould. The at least one shroud is configured to direct the inert gas from the inert gas source to the predetermined gap between the conduit, and at least one of the outlet of the vessel and the inlet of the mould.

In an embodiment of the present disclosure, the plurality of baffles are configured on at least one of outer circumference of the second wall and an inner circumference of the first wall, and each of the plurality of baffles comprises of a first element and a second element. The first element is substantially at obtuse angle to the second element, and the angle between the first element and the second element ranges from 110 degrees to 150 degrees.

In an embodiment of the present disclosure, the at least one inlet port directs the inert gas tangentially in the annular gap, and the plurality of baffles divert the flow of inert gas from tangential direction to vertical direction towards the second end of the annular gap.

In an embodiment of the present disclosure, the at least one shroud comprises a tapered portion proximal to the inlet port to direct the flow of inert gas towards the plurality of baffles.

In an embodiment of the present disclosure, the first channel and the second channel are flared at the second end of the annular gap to accelerate the discharge of the inert gas around the molten metal stream.

In an embodiment of the present disclosure, comprises at least one valve in an inert gas flow line for regulating flow rate of the inert gas into the annular gap of the shroud.

In an embodiment of the present disclosure, the molten metal is liquid steel.

In another non-limiting embodiment of the present disclosure, there is provided a shroud for discharging inert gas around molten metal stream flowing from a tundish to a mould in a continuous casting process. The shroud comprises a first channel and a second channel arranged concentric to one another forming an annular gap in between. A first end of the annular gap is closed and at least a portion of second end is configured as a passage. At least one inlet port extends from the first channel to the annular gap, the at least one inlet port is connectable to an inert gas source to receive inert gas. A plurality of baffles are configured in the annular gap, the plurality of baffles are configured to direct flow of inert gas towards the second end of the annular gap to discharge the inert gas around the molten metal stream.

In an embodiment of the present disclosure, the first channel and the second channel are concentric cylinders, and the first channel and the second channel are joined together at the first end of the annular gap. The diameter of the concentric cylinders at the first end of the annular gap is greater than diameter of the concentric cylinders at the second end of the annular gap.

In an embodiment of the present disclosure, a tapered portion proximal to the inlet port directs the flow of inert gas towards the plurality of baffles.

In an embodiment of the present disclosure, the first channel and the second channel are flared at the second end of the annular gap to accelerate the discharge of the inert gas around the molten metal stream.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristics of the disclosure are set forth in the appended description. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

FIG. 1 illustrates perspective view of an apparatus to facilitate flow of molten metal stream along with shrouds configured at inlet and outlet of conduit, according to an exemplary embodiment of the present disclosure.

FIG. 2 illustrates sectional front view of the apparatus to facilitate flow of molten metal stream of FIG. 1.

FIG. 3A illustrates sectional perspective view of the shroud provided with plurality of baffles, according to an embodiment of the present disclosure.

FIG. 3B illustrates sectional front view of the shroud of FIG. 3A.

FIG. 4 illustrates an exemplary top view of the shroud with the inlet port, according to an embodiment of the present disclosure.

FIG. 5 illustrates sectional view of the shroud provided with the inlet port to admit inert gas and plurality of baffles in the annular gap to direct flow of inert gas, according to an exemplary embodiment of the present disclosure.

FIG. 6 illustrates schematic of a baffle comprising a first element and a second element, according to an exemplary embodiment of the present disclosure.

FIG. 7 illustrates schematic of an inert gas source connected to the apparatus of FIG. 1, according to an exemplary embodiment of the present disclosure.

FIG. 8 illustrates perspective view of the shroud with inert gas curtain formed around molten metal stream, according to an exemplary embodiment of the present disclosure.

FIG. 9 illustrates schematic view of the apparatus of FIG.1 employed between a tundish and a mould to transfer molten steel for continuous casting process, according to an exemplary embodiment of the present disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its system and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

To overcome one or more limitations stated in the background, the present disclosure provides an apparatus to facilitate flow of molten metal during various manufacturing processes, including but not limited to casting. The metal that is being considered throughout the description is selected from at least one of steel and alloys of steel. However, such metal should not be construed as limitation, as the apparatus can be used for transferring any metal or non-metal in molten state during casting. Transfer of molten metal from one place to another is one of the important steps in primary manufacturing processes like casting, where metal in liquid phase (along with traces of solid and gaseous phases) is conveyed to desired location in the process chain for further processing. Since molten metal transfer involves movement of high temperature molten stream, heat transfer rate will be extremely high. The apparatus disclosed in embodiments of the present disclosure facilitates flow of such high temperature molten metal streams between processing equipment, and at the same time maintains quality and internal cleanliness of the molten metal stream during the flow. The term “internal cleanliness” herein above and below pertains to purity of molten metal and indicates the extent to which the metal is free from foreign particles causing the impurity. One of the examples of such process is continuous casting process, where liquidus metal is conveyed from storage unit, such as but not limiting to tundish, to mould where it is cooled and solidified.

The apparatus comprises a conduit placed or positioned in the path of molten metal stream, where the conduit conceals (or covers) at least a portion of the molten metal stream. The conduit includes, but not limited to, a pipe, a duct, a channel, a tube or any other member which serves the purpose. The conduit conceals only a portion of molten stream along the length of flow so that remaining portion of flow remains uncovered. Generally, one end of the conduit receives molten metal from molten metal storage unit (or reservoir), and other end of the conduit delivers molten metal to desired place, for example, a mould used in casting. The conduit is configured with an inlet and an outlet to serve this purpose, where the molten metal stream enters the conduit through the inlet and leaves the conduit from the outlet (or exit) into the mould. The conduit is positioned along the molten stream such that a predetermined gap is maintained between inlet of the conduit and outlet of the storage unit, as well as between outlet of the conduit and inlet of the mould. The predetermined gap is configured such that the conduit does not cover the molten metal stream. This allows visibility of molten stream at the uncovered portion in the flow path.

The conduit concealing the molten stream is provided with at least one shroud either on its inlet or on its outlet, or on both inlet and outlet. The at least one shroud comprises two channels viz. a first channel which is the outermost channel, and a second channel concentric to first channel. The second channel of the shroud has a smaller diameter as compared to the first channel. The first and second channels are spaced apart by a distance to form an annular gap. The annular gap is closed (or sealed) at its first end and is opened at its second end. The second end of annular gap which is opened forms a passage to allow flow of inert gas towards the predetermined gap around the molten metal stream. The inert gas stored in an inert gas source is supplied to the shroud where it enters annular gap of the shroud through at least one inlet port. The inert gas enters tangentially into the annular gap and rises up in the shroud to flow towards inlet and outlet of the conduit. The annular gap of the shroud is provided with a plurality of baffles around the periphery to divert tangential flow of the inert gas into vertical flow so that the inert gas leaves the shroud vertically. The vertical trajectory of inert gas forms an inert gas curtain at the predetermined gap around the uncovered molten metal stream, and thereby prevents atmospheric air coming in contact with the molten metal stream. The formation of inert gas curtain around the molten stream aids in preserving and maintaining quality and internal cleanliness of the liquid metal.

Further, each of the plurality of baffles comprises a first element and a second element interconnected to one another at one of the ends. In one embodiment, the first and second elements are connected such that included angle between them is substantially obtuse angle, ranging between 110 degrees and 150 degrees. The angular orientation of baffle elements effectively diverts tangential flow of inert gas into vertical flow to form inert gas curtain. The second end of the shroud from where inert gas stream exits the shroud is flared to accelerate discharge of inert gas stream in a diverging manner. Also, a portion of shroud below the plurality of baffles is tapered to direct inert gas flow towards the baffles.

In one embodiment of the present disclosure, there is provided a shroud for discharging inert gas around molten metal stream flowing from a storage unit or tundish to a mould in continuous casting process. The shroud comprises a first channel and a second channel arranged concentric to one another forming an annular gap in between them. A first end of the annular gap is closed and a portion of second end is configured as a passage to allow flow of inert gas out of the shroud towards predetermined gap. One or more inlet ports extend from the first channel into the annular gap, where the inlet port is connectable to an inert gas source to receive inert gas. A plurality of baffles is configured in the annular gap either on inner periphery of first channel or outer periphery of second channel. The plurality of baffles are configured to direct flow of inert gas towards the second end of the annular gap to discharge the inert gas around the molten metal stream in the predetermined gap.

Use of terms such as “comprises”, “comprising”, or any other variations thereof in the description, are intended to cover a non-exclusive inclusion, such that an apparatus or a device that comprises a list of components does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or apparatus or device or method. In other words, one or more elements in the apparatus proceeded by “comprising… a” does not, without more constraints, preclude the existence of other elements or additional elements in the apparatus.

Reference will now be made to an apparatus to facilitate flow of molten metal stream, and is explained with the help of figures. The figures are for the purpose of illustration only and should not be construed as limitations on the apparatus or the system. Wherever possible, referral numerals will be used to refer to the same or like parts. One may appreciate that the constructional features of casting mould and the storage unit (or reservoir) which stores the molten metal are considered to be part of the present disclosure.

FIG. 1 is an exemplary embodiment of the present disclosure which illustrates perspective view of an apparatus (100) to facilitate flow of molten metal stream (interchangeably referred to as liquid metal stream or liquidus metal throughout the description) during manufacturing processes, such as but not limiting to casting. Casting is a manufacturing process in which metals or metallic alloys are heated just above the melting point and poured into a mould with or without cavity, and allowing the liquidus metal to solidify. In an embodiment of the present disclosure, the metal transferred in its molten (or liquidus) state is liquid steel or liquidus steel alloy having predetermined composition. The liquidus metal assumes the shape of contour of the mould, and upon cooling forms a solidified mass of near net shape and dimensions. The casting process, therefore, involves melting of metals (or metallic alloys) and transferring molten metal to moulds. Conventionally, melting is performed in melting set-up including, but not limited to furnaces. Outlets of such furnaces are connected to molten metal storage units or reservoirs, commonly referred to as tundish. In some cases, molten metal is directly transferred to moulds to carry out casting process. In one embodiment of the present disclosure, molten metal is transferred from a furnace to intermediate storage reservoir [shown in FIG. 9] called “tundish”, and thereafter, the molten metal is transferred from the tundish to the mould [shown in FIG. 9] in open condition or in closed condition. During transfer of molten metal, care has to be taken to maintain temperature of molten metal above melting points to prevent any undesired solidification. In addition to these, during transfer of molten metal between furnace and moulds, optimum care has to be taken to prevent exposure of personnel to hot fumes emanating from molten gas, as well as to prevent contact of atmospheric air with molten metal to preserve its internal cleanliness. Hence, conveying or transferring molten metal within the process chain proves to be one of the crucial steps in casting process.

The apparatus (100) disclosed in the present disclosure serves the purpose of conveying molten metal stream between furnace and casting mould. The apparatus (100) not only facilitates transfer of molten metal by preventing ingress of atmospheric air into vicinity of metal stream, but also minimizes potential hazards to personnel at the time of handling molten stream during manufacturing process. The apparatus (100) is positioned in the flow path of molten metal stream in such a way that it conceals or covers (or encloses) only a portion of molten metal stream, so that the portion of molten metal stream uncovered by the apparatus (100) remains visible from distance. This allows operators to visually inspect the flow of liquid metal stream from time to time, and facilitates the user to monitor flow characteristics of liquid stream. In one embodiment of the present disclosure, the visibility of molten metal stream allows the operators to monitor flow rate of molten metal stream without any chocking or blocking in the flow path.

The apparatus (100) comprises a conduit (16) which conceals the portion of molten stream for a predetermined length along the flow path, as described in previous paragraph. The conduit (16) includes, but is not limited to channels, pipes, ducts, tubes or any other hollow members which serves the purpose. Since conduit (16) encloses molten metal stream (which is inherently at extremely high temperatures), nature of material and design characteristics of the conduit (16) are appropriately chosen at the time of manufacturing. The material selected to manufacture is such that it will not undergo any physical change or chemical change at elevated temperatures. In one embodiment of the present disclosure, material of the conduit (16) is selected from refractory materials. In addition to nature of material, the cross-section of the conduit (16) is selected such that it provides optimum flow characteristics to the molten metal. In an embodiment of the present disclosure, the cross-section of conduit (16) may be of any geometrical shape. In an exemplary embodiment, shape of the conduit (16) is at least one of circular and elliptical cross-sections. Further, as shown in FIG. 1, the conduit (16) is held vertically in flow path of molten metal stream. In this case, the molten metal stream flows in vertical direction from storage unit to the casting mould by virtue of gravity. The conduit (16) is held vertically such that the molten stream passes through the hollow opening. In an embodiment of the present disclosure, the molten metal stream does not come in contact with inner peripheral surface of the conduit (16). The length of the conduit (16) is also such that only a predetermined length of flow path of molten stream is covered by the conduit (16), while remaining portion of flow path remains uncovered. The conduit (16) serves as a barrier between molten metal and atmospheric air, thereby preventing contamination of molten metal under atmospheric contact. In an embodiment of the disclosure, the conduit (16) may be held in molten metal stream by suitable means, such as by a clip or a hook or a clamp which would receive the outer circumference of the conduit (16). The arrangement illustrated in FIG. 1 is for the purpose of illustration only and should not be construed as limitation to features of embodiments of the present disclosure.

FIG. 2 is an exemplary embodiment of the present disclosure which illustrates sectional front view of the apparatus (100) of FIG. 1. The conduit (16) comprises an inlet (17) from where molten metal stream enters, and an outlet (18) from where molten metal stream leaves the conduit (16). Precisely, the inlet (17) of the conduit (16) is proximal to storage unit (or reservoir) which stores the molten metal, and outlet (18) of the conduit (16) is proximal to casting mould. However, the inlet (17) is not directly connected to the storage unit (or reservoir) and a predetermined gap is always maintained between storage reservoir and inlet (17) of the conduit (16). Similarly, at the opposite end, a predetermined gap is maintained between outlet (18) of the conduit (16) and entry side of the casting mould.

Further, as shown in FIG. 2, the apparatus (100) comprises at least one shroud (50) configured on at least one of inlet (17) and outlet (18) of the conduit (16). The phrase “at least one” in this context indicates that a shroud (50) may be configured either on inlet side (17) of conduit (16), or on outlet (18) of the conduit (16), or both on inlet (17) and outlet (18) of the conduit (16). If the shroud (50) is configured on the inlet (17), then the outlet (18) may be directly connected to the entry side of mould. Conversely, if the outlet (18) of conduit (16) is configured with a shroud (16), then inlet (17) of the conduit (16) may be directly connected to exit of the storage unit. When the shroud (50) is configured on both inlet (17) and outlet (18) of the conduit (16), then neither the inlet (17) nor the outlet (18) is directly connected to storage unit or the mould, and predetermined gap is maintained between them as described in the previous paragraph.

The at least one shroud (50) is configurable on extremities (inlet and outlet) of the conduit (16). The shroud (50) may be mounted on the conduit (16) by techniques include, but are not limited to shrink fit and press fit, such that the innermost peripheral surface of the shroud (50) is firmly seated on outermost peripheral surface of the conduit (16) with no clearance in between them, to form a compound arrangement. Also, the shroud (50) is an external member and is not integrally formed with the conduit (16), so that it can be removably mounted on conduit (16) extremities. In other words, the shroud (50) is detachable. Hence, cross-sectional shape and dimensions of the shroud (50) are configured in conformity with cross-sectional shape and dimensions of the conduit (16). In an embodiment of the present disclosure, the cross-section of the shroud (50) is at least one of circular and elliptical. In an embodiment of the disclosure, the shroud (50) may be configured as integral element of the conduit (16).

The shroud (50) comprises a first channel (51) and a second channel (52) which are concentric to each other with respect to longitudinal axis of the shroud (50). The first and second channels (51 and 52) are essentially outer boundaries or contours of the shroud (50). The first and second channels (51 and 52) are spaced apart from each other by a distance so as to form an annular gap (45) between them along the periphery. In the present embodiment, the second channel (52) is the inner channel having smaller perimeter, and first channel (51) is the outer channel concentric to second channel (52) having greater perimeter in comparison with second channel (52). The annular gap (45) is a void space between the first and second channels (51 and 52) that allows flow of fluids. The design of first and second channels (51 and 52) is such that the fluid may have swirling movement tangentially to the peripheral surface under an external aid, such as external fluid pressure. In an embodiment of the present disclosure, if both the conduit (16) and the shroud (50) are fabricated as tubes or pipes having circular or elliptical cross-sections, then first and second channels (51 and 52) are configured as lateral wall surfaces with annular gap (45) in between them. The annular gap (45) is closed (or sealed) at its first end (45a) and is opened at its second end (45b). The first end (45a) is essentially an end of the annular gap (45) which blocks the flow of fluids out of the shroud (50), and second end (45b) is an open end which allows flow of fluid out of the annular gap (45) to leave the shroud (50). In an embodiment of the present disclosure, the first and second channels (51 and 52) of the shroud (50) are formed with U-cross section, so that the open end of U-cross section forms second end (45b) to discharge the fluid, and closed end of U-cross section forms the first end (45a) which blocks the fluid.

Further, a plurality of baffles (11) is configured around the periphery of the shroud (50) within the annular gap (45). More precisely, the plurality of baffles (11) are formed either on outer periphery of the second channel (52) (inner channel in present case) or on inner periphery of the first channel (51) (outer channel). The baffles (11) extend into the annular gap (45) either from outer periphery of second channel (52) or from inner periphery of the first channel (51). The baffles (11) are configured such that the flow characteristics and flow direction of the fluid flowing inside the annular gap (45) are altered by the presence of these baffles (11). An inlet port (20) is provisioned in the shroud (50) such that it extends between first channel (51) and the annular gap (45). The inlet port (20) forms a pathway for flow of fluid between outer periphery of the first channel (51) of the shroud (50) and the annular gap (45). The fluid enters into the annular gap (45) through the inlet port (20). The construction and operational characteristics of baffles (11) and inlet port (20) will be explained in detail in forthcoming paragraphs of detailed description.

FIGS. 3A and 3B are exemplary embodiments of the present disclosure which illustrate sectional perspective view and sectional front view of shroud (50) by removing the first channel (51). Reference is also made to FIG. 4 which illustrates top view of the shroud (50), in conjunction with FIGS. 3A and 3B. As it can be seen in FIG. 4, the annular gap (45) of the shroud (50) in between the first channel (51) and the second channel (52) is in communication with an inlet port (20) extending from outside the shroud (50). The annular gap (45) receives fluid via the inlet port (20) from an external fluid source. In an embodiment of the present disclosure, the fluid includes, but is not limited to, an inert gas intended to provide inert atmosphere to the molten metal stream. The inert gas entering the annular gap (45) through the inlet port (20) is guided in tangential direction along the periphery of annular gap (45). This is because the inlet port (20) is configured tangentially with respect to the annular gap (45) through the first channel (51). The inert gas is pressurized at the inert gas source so that it flows under pressure in the annular gap (45) between second end (45b) and first end (45a). In an embodiment of the present disclosure, the inert gas includes, but is not limited to argon, neon, krypton and any other noble gas element which provides inert atmosphere to the molten metal stream. The inert gas so entering into the annular gap (45) is guided tangentially through the contour of annular gap (45), as well as by virtue of tangential inlet into the annular gap (45) through inlet port (20). The tangential flow is then guided towards baffles (11) provided on outer periphery of the second channel (52). The baffle (11) arrangement is clearly depicted in FIGS. 3A and 3B. In an embodiment of the present disclosure, the baffles (11) are external elements which are joined either to the outer periphery of second channel (52) or to the inner periphery of first channel (51) by joining techniques, including but not limited to welding and brazing. In an alternate embodiment of the present disclosure, the baffles (11) are formed integral with first and second channels (51, 52) by non-traditional machining processes, such as, but not limited to, laser machining. The shroud (50) is also tapered (14) at a portion proximal to second end (45b) of the annular gap (45) to divert the flow of inert gas towards the plurality of baffles (11).

FIG. 5 is an exemplary embodiment of the present disclosure which illustrates sectional front view of the shroud (50) showing the flow of inert gas through the annular gap (45). As clearly shown in FIG. 5, the shroud (50) is configured with different diameters at first end (45a) of the annular gap (45) and the second end (45b) of the annular gap (45). The diameter of the shroud (50) at first end (45a) of the annular gap (45) is configured to be more when compared to the diameter of the shroud (50) at second end (45b) of the annular gap (45). Also, a tapered portion (14) is configured at a predetermined distance from the first end (45a) of the annular gap (45) to aid inward flow of inert gas towards the plurality of baffles (11). As shown in FIG. 5, the inert gas entering the annular gap (45) tangentially through the inlet port (20) will rise up in the annular gap (45) with a tangential motion. The first end (45a) of the annular gap (45) blocks the flow of inert gas and forces the inert gas to flow towards second end (45b) of the annular gap (45). The inert gas having tangential motion is initially guided by the tapered portion (14) of the shroud (50) towards the baffles (11), as clearly depicted in FIG. 5. Upon reaching the baffles (11), the tangential flow gets transformed into vertical flow. The transformation is effected by design of baffles (11) and positioning of the baffles (11) inside the annular gap (45). The transformation of flow path also results in uniform coverage of the inert gas around the periphery at a portion of annular gap (45) above the baffles (11). In addition, the positioning of baffles (11) inside the annular gap (45) with respect to shroud (50) length is determined based on flow rate requirements at second end (45b) of the annular gap (45). However, a requirement is to have optimum flow rate at the second end (45b).

The inert gas leaving the plurality of baffles (11) vertically enters flared portion (12) at the second end (45b) of annular gap (45) [clearly shown in FIG. 2]. The flared portion (12) is obtained by flaring the first channel (51) and the second channel (52) outwardly at the second end (45b) of the annular gap (45), and is intended to accelerate the flow of inert gas. The inert gas leaving the flared portion (12) of shroud (50) will have a diverging flow in vertical direction. Since flow rate at the exit of flared portion (12) is uniform, the inert gas forms a curtain or a shield around the periphery of molten metal at the predetermined gap between conduit (16) and at least one of storage unit and mould. The flared portion (12) also prevents collapse of inert gas streamline flowing outwardly from the second end (45b). The formation of inert gas curtain around the molten stream prevents air ingress (or contact) with the molten metal stream, thereby preventing contamination of the molten metal. At the same time, the presence of inert gas around the molten metal stream at the predetermined gap will not affect visibility of molten metal stream, thereby allowing the operators to easily inspect and monitor the flow of liquid metal at exit of molten metal storage unit and inlet of casting mould. An exemplary formation of inert gas curtain around the molten metal stream is depicted in FIG. 8, which is an exemplary embodiment of the present disclosure.

FIG. 6 is an exemplary embodiment of the present disclosure which illustrates construction of a baffle (11). The baffle (11) which diverts flow of inert gas inside the annular gap (45) is typically constructed of two elements viz. a first element (11a) and a second element (11b). The first element (11a) is vertical or substantially vertical, and the second element (11b) is inclined at an angle with respect to first element (11a). The baffles (11) are essentially plate like or rod like members made of metals or metal alloys or refractory material. The included angle (A) between the first element (11a) and the second element (11b) is selected to provide optimum flow characteristics across the baffles (11). In an embodiment of the present disclosure, the included angle (A) between first element (11a) and second element (11b) is obtuse, ranging from 110 degrees to 150 degrees. In addition, the dimensions of first and second elements (11a and 11b) are selected to provide uniform flow and to prevent backflow. In an embodiment of the present disclosure, the baffles (11) are fabricated as hockey shaped baffles (11) using a single member, or by joining two distinct member in preferred angular orientation.

FIG. 7 is an exemplary embodiment of the present disclosure which illustrates an inert gas source (22) connected to the apparatus (100) to supply inert gas. The inert gas source (22) includes, but is not limited to, an inert gas storage unit, such as a cylinder or a gas pipeline which stores the gas under pressure. The source (22) is equipped with a pressure gauge (23) to control delivery pressure of the inert gas flowing out of it. The control of inert gas pressure is achieved by operating the pressure gauge (23) depending on requirement. The pressurized inert gas is delivered to flow regulators (26) which control flow rate or discharge of inert gas. The flow controlled inert gas is then routed into control valves includes, but is not limited to, directional, pressure and flow control valves to vary any of the flow parameters. The inert gas with desired flow characteristics is then routed into the shroud (50) via gas flow lines (25) through the inlet ports (20). The inert gas is then guided in the annular gap (45) of the shroud (50) to form inert gas curtain around the molten metal stream at the predetermined gap, as explained in above paragraphs.

In an exemplary embodiment of the present disclosure, there is provided a shroud (50) for discharging inert gas around molten steel flowing from a tundish to a mould in a continuous casting process. Referring to FIG. 2 in conjunction with FIG. 9, the shroud (50) comprises a first channel (51) which is the outermost channel, and a second channel (52) (inner channel) arranged concentric to the first channel (51). The concentric arrangement of first and second channels (51 and 52) forms an annular gap (45) in between them, through which an inert gas is allowed to flow. The annular gap (45) comprises a first end (45a) which is closed so as to divert the flow of inert gas towards a second end (45b). A portion of second end (45b) is configured as a passage to discharge inert gas out of the shroud (50) to form an inert gas curtain around the molten metal stream. The inert gas curtain is formed at a predetermined gap between tundish and the shroud (50), as well as between entry side of mould and the shroud (50). An inlet port (20) extends from the first channel (51) to the annular gap (45), the at least one inlet port (20) is connectable to an inert gas source to receive inert gas. The inert gas flowing into the annular gap (45) through the inlet port (20) is guided as a tangential flow in the annular gap (45) until they reach vicinity of a plurality of baffles (11). Upon reaching the baffles (11), the flow gets diverted from swirling motion into uniform-vertical flow. The uniform vertical flow of inert gas diverges along the flared portion (12) at the second end (45b) of the annular gap (45) to form an inert gas curtain around the molten metal stream at the predetermined gap. The inert gas curtain serves as a barrier or a shield between molten steel and atmospheric air, thereby aids in preserving internal cleanliness and quality of molten steel flowing through the conduit (16).

It is to be understood that a person of ordinary skill in the art would design and develop an apparatus to facilitate transfer of molten metal of any configuration without deviating from the scope of the present disclosure. Further, various modifications and variations may be made without departing from the scope of the present invention. Therefore, it is intended that the present disclosure covers such modifications and variations, provided they come within the ambit of the appended claims and their equivalents.

Advantages:
The present disclosure provides an apparatus to facilitate flow of molten metal stream in a continuous casting process. The conduit provided with one or more shrouds to facilitate formation of inert curtain around the molten metal. This prevents contact of molten metal stream with atmospheric air, and thereby aids in preserving quality of the metal stream during its transfer from one place to another.

The present disclosure provides an apparatus to facilitate flow of molten metal stream in a continuous casting process. The inert gas curtain formed around the molten metal stream not only provides inert atmosphere around the molten metal stream, but also provides visibility to inspect and monitor the molten stream flow between molten metal storage unit and mould. The monitoring of molten metal flow eliminates blocking or choking of molten metal in flow path, thereby offering an effective protection (safety) to personnel handling the molten metal.

The present disclosure provides an apparatus to facilitate flow of molten metal stream in a continuous casting process, where formation of inert gas curtain around the molten metal stream eliminates need for auxiliary/separate source of a gas to divert flow of burning fumes, thereby making the instant apparatus economical and energy efficient.

The present disclosure provides an apparatus to facilitate flow of molten metal stream in a continuous casting process, where there is flexibility to the operator for emergency intervention and to interrupt the molten metal transfer process, which helps in minimizing or eliminating potential hazards during certain unanticipated events.

Equivalents
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

TABLE OF REFERRAL NUMERALS

Referral Numerals Description
100 Apparatus to facilitate flow of molten metal stream
11 Baffles
11a and 11b First element and Second element of baffle
12 Flared ends of first and second channels
14 Tapered portion of shroud
16 Conduit
17 Inlet of conduit
18 Outlet of conduit
20 Inlet port of shroud
22 Inert gas source
23 Pressure gauge
24 Valve in inert gas line
25 Inert gas line
26 Flow regulators
45 Annular gap in shroud
45a First end of annular gap
45b Second end of annular gap
50 Shroud
51 First channel
52 Second channel
A Included angle between baffle elements