Submerged entry nozzle with rotatable insert
By introducing a rotatable insert into the submerged entry nozzle, the problems of flow instability and asymmetric flow patterns were solved, enabling continuous casting of higher quality molten steel and reducing the generation of inclusions in the steel.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- REFRACTORY INTELLECTUAL PROPERTY GMBH & CO KG
- Filing Date
- 2021-04-21
- Publication Date
- 2026-05-19
AI Technical Summary
Existing submerged entry nozzles exhibit flow instability and asymmetric flow patterns during continuous casting, leading to an increase in inclusions in the steel and affecting its quality.
Introducing rotatable inserts, especially blade or propeller-type rotatable inserts, into submerged nozzles, using the flow of molten metal to drive the insert rotation, improves flow stability and reduces unwanted meniscus swirl.
The use of rotatable inserts significantly improves flow stability, reduces unwanted meniscus curling, and enhances the uniformity of molten steel flow and the quality of the steel.
Smart Images
Figure CN115315325B_ABST
Abstract
Description
[0001] This invention relates to an immersion gate with a rotatable insert, specifically an immersion entry gate (SEN), a single-cylinder gate (MT), or an immersion entry shroud (SES), through which molten steel can be poured from the tundish into the mold. This invention also relates to a method for continuous casting of molten steel using the immersion gate.
[0002] Submerged entry gates, such as submerged entry gates (SEN), monotube gates, or submerged entry long gates (SES), are known, for example, from EP 1 671 721 B1, EP 3 488 949 A1, or EP 2 382 062 B1. These gates typically comprise a generally tubular body extending from a first end to a second end, having a channel (e.g., a hole) extending along a longitudinal axis through the tubular body from the first end to the second end. In their use in continuous casting machines, the gates are typically arranged vertically, with the central longitudinal axis of the channel extending vertically, and with the first end of the tubular body located on the upper side and the second end of the tubular body located on the lower side. At least one inlet port is present at the first end, at which molten metal can enter the channel, and this inlet port leads to the channel. Multiple outlet ports are present at which molten metal can exit the channel (and leave the submerged entry gate in the mold), and these outlet ports lead to the channel in a region adjacent to the second end. In use, the sprue is usually arranged vertically, with the first end above the second end.
[0003] CN 108 436 071 A discloses a swirl-type long nozzle for continuous casting, including a swirl guiding device. EP 0 030 910 A1 discloses a submersible nozzle including blades for use in electrically driven rotary continuous casting of liquid metal. WO 2015 / 018543 A1 discloses a refractory ceramic nozzle, which includes a first groove and a second groove located within the nozzle.
[0004] One of the requirements for continuous steel casting is high flow stability from the submerged entry nozzle to the mold. This means that the flow rate of molten metal in the mold should be stable throughout the entire casting sequence. Additionally, any asymmetrical flow patterns (such as so-called meniscus curls) should be avoided. The surface velocity of the steel in the mold should be as stable as possible. All these prerequisites reduce unwanted inclusions in the steel and thereby enhance its quality.
[0005] Therefore, the object of the present invention is to provide an immersion nozzle and a method for continuous casting, wherein flow stability is improved during the pouring of molten steel from the tundish into the mold.
[0006] This objective is achieved by the submerged entry nozzle according to claim 1 (through which molten steel can be poured from the tundish into the mold), the method for continuous casting of molten steel according to claim 14, and the use of the submerged entry nozzle according to claim 15. The advantages and improvements mentioned in the method also similarly apply to product / physical purposes, and vice versa.
[0007] The core idea of this invention is based on the discovery that improved flow stability is achieved by having a rotatable insert in the submerged nozzle, and that undesirable meniscus curl can be strongly reduced or even completely prevented during casting.
[0008] In a first embodiment of the invention, this objective is achieved by providing an immersion gate through which molten steel can be poured from a tundish into a mold, the gate comprising:
[0009] - Basically a tubular body, extending from the first end to the second end;
[0010] -A channel that extends along the longitudinal axis from the first end toward the second end through the tubular body;
[0011] - At least one inlet port leading to the channel at the first end;
[0012] - Multiple exit ports leading to the passage in the area adjacent to the second end;
[0013] - and at least one rotatable insert;
[0014] - And the submersible nozzle has at least one rotatable insert, the submersible nozzle being configured to allow molten metal entering the submersible nozzle at at least one inlet port to flow through a channel and around the rotatable insert, and to exit the submersible nozzle via a plurality of outlet ports, such that the rotation of the rotatable insert is driven by the flow of molten metal.
[0015] Preferably, at least one rotatable insert is located inside the channel.
[0016] More preferably, at least one rotatable insert is located in the region adjacent to the second end inside the channel.
[0017] Preferably, the rotatable insert rotates relative to the substantially tubular tubular body as a fluid (such as molten steel / molten metal) flows through the channel.
[0018] Preferably, the rotatable insert is not connected to the tubular body, allowing the rotatable insert to rotate. Preferably, the outer diameter (such as the maximum outer diameter) of the rotatable insert is smaller than the inner diameter of the channel (especially in the region adjacent to the second end).
[0019] Preferably, the rotation axis of the rotatable insert coincides with the longitudinal axis (A) of the tubular body.
[0020] Preferably, at least one inlet port of the immersion nozzle includes an inlet port.
[0021] Preferably, the height of the rotatable insert is greater than the (maximum) height of the multiple outlet ports.
[0022] Preferably, the submersible inlet according to the present invention is a submersible inlet (SEN), a single-cylinder inlet (MT), or a submersible long inlet (SES).
[0023] Preferably, at least one rotatable insert includes blades. Preferably, the blades are capable of driving the rotation of the insert when fluid flows through the channel.
[0024] Preferably, at least one rotatable insert defines a rotation axis and includes blades, the angle between at least one surface normal of the blade and the rotation axis being in the range of 10° to 85°, more preferably in the range of 20° to 80°. In use, such an insert will rotate about the rotation axis due to the force of the flowing fluid. The angle between at least one surface normal of the blade and the rotation axis should be understood as the smaller angle (i.e., <90°) between a first line (or direction) defined by at least one surface normal of the blade (i.e., the direction of the surface normal of the blade) and a second line (or direction) defined by the rotation axis.
[0025] Preferably, at least one rotatable insert comprises 2 to 15 blades. More preferably, at least one rotatable insert comprises 3 to 15 blades.
[0026] Preferably, at least one rotatable insert includes a shaft.
[0027] At least one rotatable insert can be in the form of a propeller. Preferably, at least one rotatable insert is in the form of a propeller with at least 3 blades. At least one rotatable insert is in the form of a propeller with at most 15 blades.
[0028] Preferably, the thruster may include a shaft. Alternatively, the thruster may be a shaftless thruster.
[0029] Preferably, at least one rotatable insert is in the form of a thruster having a thruster pitch of at least 50 mm, preferably 100 mm, more preferably 200 mm.
[0030] Preferably, at least one rotatable insert is in the form of a thruster having a thruster pitch of less than 2000 mm, preferably less than 1500 mm, more preferably less than 1000 mm.
[0031] At least one rotatable insert may be made of a refractory material. Preferably, at least one rotatable insert is made of a fine-grained refractory material, such as a refractory material with a maximum particle size of less than 2 mm, preferably less than 1 mm, and more preferably less than 0.7 mm. This allows for a smooth surface of the insert, especially for blades. Preferably, at least one rotatable insert is made of boron nitride. This produces a highly stable geometry for the insert.
[0032] Preferably, the substantially tubular tubular body includes a wear-resistant liner section inside the channel. Preferably, the rotatable insert is positioned in a region of the wear-resistant liner section inside the channel. Preferably, the wear-resistant liner section extends to a second end. Preferably, the wear-resistant liner section forms a retainer or sleeve for the rotatable insert. The wear-resistant liner section reduces friction between the channel wall and the rotatable insert.
[0033] In one implementation, the submerged nozzle is produced by isostatic pressing. In this case, the wear-resistant liner section is particularly useful because it allows for simpler manufacturing with high dimensional accuracy.
[0034] In a second embodiment of the invention, this objective is achieved by providing a method for continuous casting of molten steel using a sprue according to the invention. The invention also relates to continuous casting of molten steel using a submerged entry nozzle according to the invention. This method allows for the production of high-quality steel due to a reduction in the amount of inclusions caused by the stability of the metal flow.
[0035] Other features of the invention will be known from the claims, the accompanying drawings, and the following description of the drawings.
[0036] All features of this invention can be combined individually or in combination. Exemplary embodiments of the invention will be explained in more detail below:
[0037] Figure 1 A schematic cross-section of a schematic submersible inlet (SEN) with a rotatable insert is shown.
[0038] Figure 2 A schematic cross-section of a schematic monotube nozzle with a rotatable insert is shown.
[0039] Figure 3 A schematic perspective view of an embodiment of the first rotatable insert is shown.
[0040] Figure 4 A schematic perspective view of an embodiment of the second rotatable insert is shown.
[0041] Figure 5a The flow pattern of the dual rolls is illustrated schematically.
[0042] Figure 5b The flow pattern of a single roll is illustrated schematically.
[0043] Figure 5c The flow pattern of the meniscus roll is schematically illustrated.
[0044] Figure 6 A schematic cross-section of a schematic submersible inlet (SEN) with a rotatable insert and a wear-resistant liner section is shown.
[0045] Figure 1 A cross-section of an immersion inlet (1) in its place of use is shown; the immersion inlet is an immersion inlet (1a). The immersion inlet (1) comprises a generally tubular tubular body (2) extending from a first end (3) (upper end) to a second end (4) (lower end), the generally tubular tubular body (2) being made of carbon-bonded refractory material. The immersion inlet (1) also includes a channel (5) extending along a longitudinal axis (A) through the tubular body (2) from the first end (3) to the second end (4). The channel (5) defines a rotationally symmetrical opening, here in the form of a cylinder, wherein the axis of the opening coincides with the longitudinal axis (A) of the immersion inlet (2). At the first end (3), an inlet port (6) opens into the channel (5). In a region (7) adjacent to the second end (4), two outlet ports (8) open into the channel (5). The outlet ports (8) are circular openings in the wall of the tubular body (2). The submersible inlet (1) also includes a rotatable insert (10). The rotatable insert (10) is located in a region (7) adjacent to the second end (4) inside the channel (5). The submersible inlet (1) having at least one rotatable insert (10) is configured such that molten metal entering the submersible inlet (1) at at least one inlet port (6) flows through the channel (5) and around the rotatable insert (10), and exits the submersible inlet (1) via a plurality of outlet ports (8), such that the rotation of the rotatable insert (10) is driven by the flow of molten metal. When a fluid such as molten metal flows through the channel (5), at least one rotatable insert (10) rotates relative to the substantially tubular tubular body (2).
[0046] Figure 2 A cross-section of an immersion nozzle (1) in its place of use is shown; this immersion nozzle is a monotube nozzle (1b). With Figure 1 The difference between the submersible nozzle (1a) and the monotube nozzle (1b) shown lies in the geometry at its first end (3). Here, the monotube nozzle (1b) is shown with a connection portion for attaching to a sliding gate plate accessory (not shown). Apart from the different attachment geometry at its first end (3), the other parts of the monotube nozzle (1b) are functionally similar to the coupling. Figure 1The corresponding part described in the submersible inlet (1a).
[0047] Figure 3 A schematic perspective view of an embodiment of a first rotatable insert (10) is shown, wherein at least one rotatable insert (10) defines a rotation axis (13). Here, at least one rotatable insert (10) is in the form of a propeller having a shaft (12) and four blades (11), characterized in that the angle between the corresponding surface normal (14) of the blade (11) and the rotation axis (13) is constant on the insert (10). In this example, at least one rotatable insert (10) is in the form of a propeller with a propeller pitch of 400 mm, which is 560 mm in an alternative setting. At least one rotatable insert (10) is made of a fine-grained refractory material, here at least one rotatable insert (10) is made of boron nitride with a maximum particle size of 0.3 mm.
[0048] Figure 4 A schematic perspective view of an embodiment of the second rotatable insert (10) is shown, wherein at least one rotatable insert (10) defines a rotation axis (13). Here, at least one rotatable insert (10) is in the form of a shaftless propeller with 10 blades (11) (this design can be referred to as a Francis turbine). In this example, at least one rotatable insert (10) is in the form of a propeller with a propeller pitch of 450 mm. At least one rotatable insert (10) is made of a fine-particle refractory material, here, at least one rotatable insert (10) is made of boron nitride with a maximum particle size of 0.3 mm. Figure 4 The rotatable insert (10) can be used according to Figure 1 and Figure 2 In the implementation method.
[0049] The mold flow pattern of the submersible nozzle according to the present invention is compared with that of a submersible nozzle having an empty casting channel. By measuring the flow velocity in the water mold, the following basic flow patterns can be observed in the mold (here, the mold is rectangular in shape):
[0050] The first observed flow pattern (see Figure 5a The preferred flow pattern is the so-called double-roll. Here, for each outlet port, the fluid flow leaving the submerged nozzle presents as two swirling patterns: one swirling pattern pointing substantially above the outlet port and the other swirling pattern pointing in the opposite direction and substantially below the outlet port. This flow configuration is preferred because it minimizes non-metallic inclusions in the steel.
[0051] The observed second flow pattern (see Figure 5b This is acceptable, but not preferred, and is known as single-roll. Here, for each outlet port, the fluid flow leaving the submersible nozzle exhibits a single (single) roll pattern, where the initial flow is upward (towards the meniscus; the meniscus is understood as the surface of the liquid) and then rolls downward. This flow configuration is acceptable, but not preferred, due to the risk of non-metallic inclusions in the steel.
[0052] The observed third flow pattern should be avoided (see Figure 5c This is known as a meniscus roll. Here, for one of the outlet ports, the fluid flow leaving the submerged nozzle exhibits two roll patterns, while for the second outlet port, the fluid flow leaving the submerged nozzle exhibits a single roll pattern, thus creating a mixture of single and double rolls. This flow configuration should be avoided or minimized because it increases the risk of non-metallic inclusions in the steel.
[0053] The results for the flow patterns observed for different geometries are shown in Table 1 below. All experiments were conducted for 30 minutes in a water model (scaled down 1:3) at an equivalent steel yield of 3.16 tons per minute.
[0054] In the first experiment, in (according to) Figure 1 (of) Submersible sprue internal use such as Figure 3 The first rotatable insert is shown. During the experimental measurements, the observed flow pattern was a double-roll case 99.8% of the time (according to...). Figure 5a No single volume was observed at all. Figure 5b And an extremely low percentage (0.2%) of meniscus rolls were observed. Figure 5c )Condition.
[0055] In the second experiment, in (according to) Figure 1 (of) Submersible sprue internal use such as Figure 4 The second rotatable insert is shown. The flow pattern observed 100% of the time during the experimental measurements is shown as a double-roll case (reference). Figure 5a No single volume was observed at all. Figure 5b ) or meniscus roll ( Figure 5c (The situation is as follows.)
[0056] In the third experiment, no insert was used inside the submersible nozzle (comparative example). During the experimental measurements, the observed flow pattern was double-rolled for 83.8% of the time (reference). Figure 5a A single-volume situation exists 0.5% of the time. Figure 5b Furthermore, meniscus-like rolls were observed 15.8% of the time. Figure 5c ).
[0057] In summary, experiments show that using a rotatable insert in an immersion nozzle reduces (undesirable) meniscus curl compared to an empty channel. Figure 5c Therefore, the rotatable insert in the submersible nozzle improves flow stability because it achieves highly stable double-roll flow characteristics.
[0058] Figure 6 It shows the connection with Figure 1 The cross-section of the submersible nozzle (1) is similar to that of the submersible nozzle, except that the substantially tubular body (2) includes a wear-resistant liner section (15) inside the channel (5), and wherein a rotatable insert (10) is positioned within the region (7) of the wear-resistant liner section (15) inside the channel (5). The wear-resistant liner section (15) extends to the second end (4) of the channel (5). The wear-resistant liner section (15) is formed separately prior to the production of the entire submersible nozzle (1), and in this example, it is formed as a cage / sleeve. It is shown that in the case where the submersible nozzle (1) is produced by isostatic pressing, the production process is simplified, and the cage / sleeve forming the wear-resistant liner section (15) enables enhanced dimensional accuracy, and thus demonstrates the improvement and more constant rotation of the rotatable insert (10).
[0059] Table I: Using the first rotatable insert ( Figure 3 ), second rotatable insert / Francis turbine insert ( Figure 4 Comparison of flow patterns (double roll, single roll, or meniscus roll) observed in an empty casting channel or a standard casting channel, as a percentage of total time:
[0060]
[0061] Reference labels and factor list:
[0062] 1 Submersible water inlet
[0063] 1a Submersible Inlet (SEN)
[0064] 1b Single-cylinder sprue
[0065] 1c Submersible Inlet Long Sprue (SES)
[0066] 2 tubular body
[0067] 2a Slag belt
[0068] 3 First end
[0069] 4 Second end
[0070] 5 channels
[0071] 6. Entry Ports
[0072] 7. The area adjacent to the second end (4)
[0073] 8 Export Ports
[0074] 10 Rotatable inserts
[0075] 11 blades
[0076] 12-axis
[0077] 13. Axis of rotation
[0078] 14. Surface normal of blade (11)
[0079] 15 Wear-resistant inner liner sections / cages for rotatable inserts
[0080] A. Longitudinal axis of the tubular body (2)
Claims
1. A submerged entry nozzle (1) through which molten steel can be poured from a tundish into a mold, the nozzle comprising: 1.1 A basically tubular tubular body (2) extending from a first end (3) to a second end (4); 1.2 Channel (5), extending along longitudinal axis (A) from the first end (3) toward the second end (4) through the tubular body (2); 1.3 At least one inlet port (6) leading to the channel (5) at the first end (3); 1.4 Multiple exit ports (8) leading to the channel (5) in a region (7) adjacent to the second end (4); 1.5 and at least one rotatable insert (10); 1.6 Among them, The immersion inlet (1) having at least one rotatable insert (10) is configured such that molten metal entering the immersion inlet (1) at at least one inlet port (6) flows through the channel (5) and around the rotatable insert (10), and exits the immersion inlet (1) via the plurality of outlet ports (8), such that the rotation of the rotatable insert (10) is driven by the flow of the molten metal.
2. The submersible sprue (1) according to claim 1, wherein, The at least one rotatable insert (10) is located inside the channel (5).
3. The submersible sprue (1) according to claim 2, wherein, The at least one rotatable insert (10) is positioned in the region (7) adjacent to the second end (4).
4. The submersible inlet (1) according to any one of claims 1 to 3, wherein, The submersible inlet (1) is a submersible inlet (SEN) (1a).
5. The submersible inlet (1) according to any one of claims 1 to 3, wherein, The rotatable insert (10) defines a rotation axis (13) and includes a plurality of blades (11), wherein the angle between at least one surface normal (14) of the blade and the rotation axis (13) ranges from 10° to 85°.
6. The submersible inlet (1) according to claim 5, wherein, The angle between at least one surface normal (14) of the blade and the axis of rotation (13) ranges from 20° to 80°.
7. The submersible inlet (1) according to any one of claims 1 to 3, wherein, The rotatable insert (10) has at least two blades.
8. The submersible inlet (1) according to claim 7, wherein, The rotatable insert (10) is in the form of a propeller with at least 3 blades.
9. The submersible inlet (1) according to any one of claims 1 to 3, wherein, The rotatable insert (10) is in the form of a propeller with up to 15 blades.
10. The submersible inlet (1) according to any one of claims 1 to 3, wherein, The rotatable insert (10) is in the form of a thruster with a thruster pitch of at least 50 mm.
11. The submersible inlet (1) according to claim 10, wherein, The rotatable insert (10) is in the form of a thruster with a thruster pitch of at least 100 mm.
12. The submersible sprue (1) according to claim 10, wherein, The rotatable insert (10) is in the form of a thruster with a thruster pitch of at least 200 mm.
13. The submersible inlet (1) according to any one of claims 1 to 3, wherein, The rotatable insert (10) is in the form of a thruster with a thruster pitch of less than 2000 mm.
14. The submersible sprue (1) according to claim 13, wherein, The rotatable insert (10) is in the form of a thruster with a thruster pitch of less than 1500 mm.
15. The submersible inlet (1) according to claim 13, wherein, The rotatable insert (10) is in the form of a thruster with a thruster pitch of less than 1000 mm.
16. The submersible inlet (1) according to any one of claims 1 to 3, wherein, The rotatable insert (10) is made of refractory material.
17. The submersible inlet (1) according to claim 16, wherein, The at least one rotatable insert (10) is made of boron nitride.
18. The submersible inlet (1) according to any one of claims 1 to 3, wherein, The rotatable insert (10) is made of fine-particle refractory material with a maximum particle size of less than 2 mm.
19. The submersible inlet (1) according to claim 18, wherein, This refractory material is a refractory material with a maximum particle size of less than 1 mm.
20. The submersible inlet (1) according to claim 18, wherein, This refractory material has a maximum particle size of less than 0.7 mm.
21. The submersible inlet (1) according to any one of claims 1 to 3, wherein, The tubular body (2), which is essentially tubular, includes a wear-resistant liner section (15) inside the channel (5), and wherein the rotatable insert (10) is located inside the channel (5) in the region (7) where the wear-resistant liner section (15) is located.
22. The submersible sprue (1) according to claim 21, wherein, The wear-resistant lining section (15) extends to the second end (4).
23. The submersible inlet (1) according to any one of claims 1 to 3, wherein, The immersion nozzle (1) is produced by isostatic pressing.
24. The purpose of the submerged nozzle (1) according to any one of claims 1 to 23 is for continuous casting of molten steel.