Apparatus for stirring and methods of stirring

Abstract

A method of stirring and apparatus for stirring using electromagnetic stirrer units is provided. The method and apparatus are particularly useful in relation to molten metal stirring. Each stirrer unit is mounted on a moveable carriage so that it can be moved between a first location, a second location and potentially further locations. The same stirrer unit is used to provide stirring at each location, so allowing multiple locations to be stirred but only requiring a single stirrer unit to do so. The method and apparatus also provide convenient connection of air cooling to the stirrer unit.

Claims

1. An apparatus for stirring, the apparatus including: a) one or more electromagnetic stirrer units; b) a moveable mounting for each of the one or more electromagnetic stirrer units; and c) a support system configured to move each of the one or more electromagnetic stirrer units away from the respective moveable mounting; and wherein, the apparatus has a first state in which one of the electromagnetic stirrer units is at a first location selected from amongst a number of locations and the one or more electromagnetic stirrer units are configured for stirring at that first location; and the apparatus has a second state in which the same one or more electromagnetic stirrer units are at a second location selected from amongst the number of locations and the one or more electromagnetic stirrer units are configured for stirring at that second location, the second location being different to the first location; and wherein the apparatus further includes a coolant source, wherein the coolant source is in fluid communication with a first interface at the first location and the coolant source is in fluid communication with a second interface at the second location, the first interface or second interface provides for fluid communication between the coolant source and the electromagnetic stirrer unit when the electromagnetic stirrer unit is at a location; and wherein the coolant source is provided at a fixed position relative to the first location and the second location.

2. The apparatus according to claim 1 in which the stirrer unit is in fluid communication with the coolant source, the coolant being air, when at the first location.

3. The apparatus according to claim 1 in which the electromagnetic stirrer provides stirring of molten metal, the molten metal being provided in a container, the container being selected from the group consisting of: a furnace, a ladle, a storage vessel, a transport vessel and a holding furnace.

4. The apparatus according to claim 1 in which the electromagnetic stirrer unit is moveably mounted by being provided on a carriage and the carriage provides the capacity to move the electromagnetic stirrer unit from the first location to the second location.

5. The apparatus according to claim 1 in which the electromagnetic stirrer unit has at least two positions, the electromagnetic stirrer unit having a first position, the first position being used during movement of the stirrer from the first location to the second location, and/or the electromagnetic stirrer unit having a second position, the second position being not used during movement of the electromagnetic stirrer from the first location to the second location, the electromagnetic stirrer unit providing stirring when in the second position.

6. The apparatus according to claim 1 further comprising one or more conduits to provide fluid communication for the coolant to the electromagnetic stirrer unit, and one or more further conduits to provide fluid communication for the coolant away from the electromagnetic stirrer unit.

7. The apparatus according to claim 1 in which the number of locations is more than two and/or the number of locations at which stirring is to be provided exceeds the number of electromagnetic stirrer units provided by at least one.

8. The apparatus according to claim 1 in which the electromagnetic stirrer unit is in fluid communication with the coolant source when at the first location and when at each of the locations at which stirring is to be provided, wherein the source of coolant to the first and each location is the same.

9. The apparatus according to claim 1 in which the electromagnetic stirrer unit is in fluid communication with an exit for coolant when at the first location and when at each of the locations at which stirring is to be provided, the exit for the coolant at the first and each location is the same.

10. The apparatus according to claim 1 in which the first interface and/or second interface is provided aligned with the direction of movement of the electromagnetic stirrer unit and/or carriage towards the location where the first interface and/or second interface is provided.

11. The apparatus according to claim 1 in which the first interface and/or second interface is provided in two parts, one interface part is provided on the electromagnetic stirrer unit, and one part of the interface is provided on a conduit in fluid communication with the coolant source.

12. The apparatus according to claim 11 in which the first interface and/or second interface includes a contact surface, the contact surface is provided on only one interface part.

13. The apparatus according to claim 11 in which the two parts of the first and/or second interface provide for fluid communication through the first interface and/or second interface when the two parts abut one another, the two parts of the first interface and/or second interface being brought into abutment by the electromagnetic stirrer unit moving to the location from another location.

14. The apparatus according to claim 11 in which the first interface and/or second interface provides for fluid communication between the coolant source and the electromagnetic stirrer unit at a location, with an exit interface providing the exit for the coolant from the electromagnetic stirrer unit, and at a different location, the exit interface provides for fluid communication between the coolant source and the electromagnetic stirrer unit, with the interface providing the exit for the coolant from the electromagnetic stirrer unit.

15. The apparatus according to claim 1 in which the first interface and/or second interface include a seal promoting element, with the seal promoting element provided on only one interface part.

16. The apparatus according to claim 1 in which the first interface and/or second interface includes an inlet with a contact surface extending around at least a part of the circumference of the inlet, the contact surface having an extent radially about the axis of the inlet, the extent being less than the extent of a seal promoting element.

17. The apparatus according to claim 1 in which the stirrer unit is disconnected from fluid communication with the first interface when moving between the first location and the second location.

18. The apparatus according to claim 1 wherein the support system comprises one or more support arms configured to move each of the one or more electromagnetic stirrer units away from the respective moveable mounting.

19. The apparatus according to claim 18 wherein the support arms are configured for moving the one or more electromagnetic stirrer units in a scissor lift configuration.

Description

(1) Various embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

(2) FIG. 1 is a side view of the stirring system in one position;

(3) FIG. 2 is a perspective view of a stirring system showing the single stirrer at each of three locations for the purposes of illustration;

(4) FIG. 3a shows the cooling gas connection in a first state;

(5) FIG. 3b shows the cooling gas connection of FIG. 3a in second state.

(6) Electromagnetic stirrers are known for stirring the molten metal contents of a variety of vessel types, including furnaces, holding vessels, ladles etc. The electromagnetic stirrers are positioned adjacent the vessel and hence are operating in a hot environment and generate internal heat during operation. For this reason, they are often actively cooled, with air being a preferred coolant.

(7) Electromagnetic stirrers are expensive pieces of equipment and are not in full time operation for any one vessel as they are not needed during parts of the molten metal handling cycle.

(8) The applicant proposes in this document a stirring system and stirring method whose approach allows a single electromagnetic stirrer to be used at a number of different stirring locations, whilst conveniently providing cooling at those stirring locations.

(9) Referring to FIG. 1, a centrifugal pump or fan 1 for the coolant, in this case air, is provided. The pump 1 draws in filtered air from the environment of the pump 1 and supplies it to an outlet 3. The pump 1 is provided at a first floor level 5 and the outlet 3 conveys the air down to a lower level 7. The outlet 3 ends at an interface 9.

(10) As shown, the interface 9 provides fluid communication between the outlet 3 and the stirrer supply conduit 11. The stirrer supply conduit 11 carries the coolant under the stirrer 13 to three stirrer inlets 15. Each stirrer inlet 15 conveys coolant up into the stirrer 13. Suitable baffles or the like (not shown) are provided to ensure consistent coolant delivery to each stirrer inlet 15. The stirrer inlets 15 convey the coolant into the housing 17 of the stirrer 13 where heat transfer to the coolant provides the necessary cooling effect under the control of suitable internal designs, including baffles and the like.

(11) The heated coolant exits the housing 17 and returns down stirrer outlet (directly behind the inlets in the illustration) and hence into the stirrer supply conduit 11 from where the coolant flows away, to the left-hand side as shown and then out to atmosphere.

(12) In this way the necessary cooling is provided.

(13) As shown in FIG. 1, the stirrer 13 is in the retracted, inactive position. Hydraulics 23 and suitable support arms, potential as a scissor lift, provide the motion to lift the stirrer 13 up and away from the carriage 24 it rests upon. In the elevated position, the stirrer 13 is closer to the furnace (not shown) and so is better able to provide the active stirring position. As the stirrer 13 is lifted, flexible sections of the stirrer inlets 15 allow the required motion. Concertina or bellowed sections or the like can be used for this purpose. Mechanical and other forms of mechanism may be used to provide the motion to the stirrer 13.

(14) The support carriage 24 allows the stirrer 13 to be moved from one location to another location where stirring is required. This allows a single stirrer 13 to be used at multiple locations, rather than have the capital cost of a stirrer 13 at leach of those locations.

(15) At each stirring location the stirrer 13 is provided with air cooling. As described above, this is through connection to a pump or fan 1, and the outlet 3 therefrom. That connection could be made when the stirrer 13 is present at the stirring location and then be broken when the stirrer 13 is moved away from that location. Such a situation would occur if the fan 1 in FIG. 1 was fixed in position, but the stirrer 13 on its carriage 24 was moveable relative to the fan 1; a situation described in more detail below in relation to the FIG. 2, FIG. 3a and FIG. 3b embodiments.

(16) Alternatively, and as illustrated in FIG. 1, the fan 1 can itself be mounted on a fan carriage 26 which is also adapted for movement and which is connected to the carriage 24 on which the stirrer 13 is provided by a link 28. The link 28 means that as the carriage 24 and its stirrer 13 are moved then the fan carriage 26 and its fan 1 move too. This maintains the connection between the outlet 3 from the fan 1, via the interface 9 to the stirrer supply conduit 11, and allows the air to pass to the stirrer 13. Of course, the link 28 also means that as the fan carriage 26 and its fan 1 are moved then the carriage 24 and its stirrer 13 move too. In a further alternative, not illustrated, the fan 1 can be mounted on the same carriage 24 as the stirrer 13, so that the two move about together.

(17) In FIG. 2, the general principle outlined in FIG. 1 has been extended to show the use of a single stirrer 13 to provide an active stirring position at a first location 25 and a second location 27. The first location 25 is linked to the second location 27 by means of a channel 29 in the foundations 31 of the plant site. In this case, a linear channel 29 is shown but other channel shapes are possible which accommodate the stirrer 13 and its support carriage 24.

(18) An intermediate position 33 is also provided part way along the channel 29 which allows for easy access to the stirrer 13, hydraulics 19, support arms and carriage 24 for maintenance purposes.

(19) For illustrative purposes the stirrer 13 is shown in FIG. 2 as though it were at all three locations, but in reality only one stirrer 13 is provided in the channel 29.

(20) The single cooling fan 1 at position 35 provides coolant to the outlet 3 as before. In this embodiment, the fan 1 is in a fixed position on the foundations 31. The fan 1 does not move; otherwise the manner of connection is very similar to the FIG. 1 embodiment.

(21) The outlet 3 extends the full length of the channel 29 and goes down into the channel 29 at each end to provide an interface 9a for the first position 25 and an interface 9b for the second location 27.

(22) In use, when stirring is desired at the first location 25, the stirrer 13 is moved on its carriage 24 along the channel 29 until it is at the first location 25. The movement to the first location 25 connects the stirrer supply conduit 11 to the outlet 3 via the interface 9a. This is described in more detail below. With the stirrer 13 at the first location 25, the stirrer 13 can be elevated and the stirring performed for the requisite time. The stirrer 13 can then be taken to the retracted, inactive position, and can then be moved along the channel 29 to the second location 27 to provide stirring there. Again the movement to the second location 27 provides the connection of the outlet 3 via the interface 9b to the stirrer supply conduit 11.

(23) As mentioned above, the number of locations at which stirring can be provided can be increased by stopping the stirrer 13 at other locations and/or by providing other channel or rail configurations.

(24) The same general approach can be provided for side mounted stirrers which act through the side walls of vessels, rather than through the base, on the metal contents.

(25) The operation of the interface 9 is shown in more detail in FIGS. 3a and 3b.

(26) FIG. 3a shows the outlet 3 in the end wall 50 of the channel 29, with that end wall 50 being part of the foundations 31 of the plant. The outlet 3 is surrounded by the interface 9 which is formed of a holding frame 52 provided around a square neoprene section 54. Whilst neoprene is a suitable material, a variety of other materials are also suitable to provide the preferred sealing function.

(27) To either side of the outlet 3 are the rail supports 55 and the rails 56 provided on top so as to provide the running surface for the carriage 24 carrying the stirrer 13. In this illustration the stirrer 13 and the carriage 24 have both been omitted, apart from the carriage interface part 58.

(28) The carriage interface part 58 is formed of a cylindrical section 60, which is connected to the stirrer supply conduit 11, together with a metal flange 62.

(29) As shown in FIG. 3a, the flange 62 and the neoprene section 54 are spaced apart and so the fluid communication between the outlet 3 and the stirrer supply conduit 11 has not been formed.

(30) Advancing the carriage 24 towards the end wall 50 of the channel 29 reduces and then eliminates the space such that the metal flange 62 abuts the neoprene section 54 and a seal is provided. Coolant can now flow due to the fluid communication provided.

(31) The heated coolant exits the other end of the carriage 24 and can either vent to atmosphere or more desirably be connected to an exhaust interface (not shown in FIGS. 3a, 3b). The exhaust interface can be separate from or could be the same as the interface at the other location. A conduit extending between the rails 56 and extending the length of the channel 29 could be used, with suitable concertina sections, bellows or the like to accommodate the conduit in reduced or increased length form as the carriage 24 and stirrer 13 move locations.

(32) Any suitable mechanism can be used to move the carriage 24 etc from location to location.

(33) The channel 29 may be formed at the same time as the plant's construction or could be retro fitted.

(34) Instrumentation is provided to confirm that cooling air is flowing and potentially to measure the flow rate thereof.