CN201603853U - A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs - Google Patents

Abstract

A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs, including a cylindrical tubular nozzle body with a central through hole, and a funnel-shaped molten steel inlet at the upper end of the nozzle body , the bottom of the lower end is sealed, and a pair of molten steel upper spout holes and a pair of molten steel lower spit holes, which are not at the same height and are of rectangular structure with chamfers, are arranged on the lower part of the nozzle body, which are opposite to each other. The center point of the upper spit hole and the center point of the lower spit hole on the same side are in a straight line in the vertical direction. In addition, the four spit holes and the horizontal line all form a certain angle, and the two spit holes on the same side The included angles of the two spit holes are opposite. The four-hole submerged nozzle used for pouring conventional slabs to prevent turbulent flow of molten steel has a simple structure and low cost, and is suitable for pouring conventional slabs in the field of iron and steel metallurgy, reducing the turbulent flow of molten steel inside the slab crystallizer and reducing the cost. The flow field is stabilized and the quality of the continuous casting slab is improved.

Description

A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs

technical field

The utility model relates to the field of supplying or processing molten metal in metal continuous casting, in particular to a four-hole submerged nozzle used for pouring conventional slabs, which can reduce the turbulent flow of molten steel inside the slab crystallizer and stabilize the flow field, and belongs to the metallurgical continuous casting process. casting equipment.

Background technique

At present, various iron and steel manufacturers usually use submerged nozzles in the production process of continuous casting slabs. During the continuous casting process, submerged nozzles play the role of diversion and protection of molten steel, forming a flow field and uniform temperature in the mold. The molten steel is distributed and cooled by water in the crystallizer to form a solidified billet shell with uniform thickness. In order to form a stable initial solidified slab shell in the crystallizer and avoid slag entrainment, metallurgists have designed submerged nozzles of various shapes to obtain good molten steel flow patterns and slab quality.

However, during the use of the submerged nozzle in the prior art, the molten steel moves in a straight line after coming out of the side hole of the nozzle, and expands and flows to the narrow surface of the crystallizer on the one hand, which forms a strong impact on the initial billet shell. When the stream reaches the narrow face of the crystallizer, it is divided into two streams, upward and downward. The upward stream forms a vortex recirculation area near the liquid surface. This recirculation plays a vital role in the floating of inclusions, the fluctuation of the crystallizer liquid level and the entrainment of slag. At the same time, the surface velocity of this reflow affects the melting of mold powder. Also plays an important role, therefore, the upper backflow has an important relationship with the surface quality of the slab. The lower part of the crystallizer forms a large-scale recirculation zone opposite to the upper circulation direction, and its strength weakens with the extension of the downward distance, which has an important impact on the solidified billet shell at the crystallizer outlet. At the same time, the fine air bubbles involved in the downflow will adhere to the inclusions and move together with the molten steel, forming inclusions aggregation at the solidification front of the slab. This phenomenon has a serious impact on the internal quality of the slab and subsequent processes. Therefore, when casting slabs with double-hole nozzles, the four large backflows in the crystallizer will affect the surface and internal quality of the slab. From the perspective of the submerged nozzle, in order to produce high-quality billet and ensure the stability of pouring, the following points must be done:

1. Reduce the fluctuation of crystallizer liquid level;

2. Reduce the inclusion of mold slag and avoid the impact of molten steel on the solidified shell;

3. Avoid bubbles and inclusions that are difficult to float up caused by too deep impact of molten steel;

4. It is also necessary to ensure sufficient steel flow.

The Chinese patent with the publication number CN2108596 is a special-shaped submerged nozzle. The upper end of the nozzle is a conical funnel, the middle end is an elliptical nozzle, and the lower end is a bottom cover. There are two horizontal or downward water outlets and the whole body of the water outlet. The design of the extension section can evenly distribute the molten steel inside the crystallizer.

Although the patent improves the uniform distribution of molten steel, the molten steel in the submerged nozzle still directly impacts the slab shell after flowing out, which affects the quality of the slab.

The Chinese patent of publication number CN2362624-a submerged nozzle for continuous casting of thin slabs, its profile, main channel and outlet shape are all oblate ellipse. The outlets are located on both sides of the nozzle, and there are at least two pairs (four). By dispersing the steel stream into up-dipping streams and down-dipping streams, the kinetic energy and impact force of the streams are weakened, and they collide in the mold to dissipate the momentum of each other, thereby reducing the turbulent flow of the mold liquid surface at the same time , reducing the impact of the steel flow on the solidified shell.

The submerged nozzle of the above-mentioned patent can only be used for pouring thin slabs, because in the production of thin slabs, the casting speed is high, and the mold space is limited, which is different from the working nature of the utility model for pouring conventional slabs.

Chinese Patent Publication No. CN2834744 - a continuous casting tundish submerged nozzle, including tapping holes on the opposite sides of the side wall of the nozzle cylinder, which is characterized in that there are four tapping holes, two of which are symmetrical on one side Distribution, two tapping holes on one side are arranged on the side wall of the nozzle end in a vertical arrangement, the upper tapping hole is at a downward inclination angle, the lower tapping hole is at an upward inclination angle, and the bottom of the nozzle cylinder is conical or arc-shaped.

The above-mentioned patent alleviates the flow field disturbance in the mold by reducing the impact of the stream on the slab shell. Although it can slow down the surface velocity of the molten steel in the mold and shorten the floating stroke of the inclusions, this patent can only be used for continuous casting tundish Use is different from the nature of work for pouring conventional slabs where the utility model is located.

In summary, the four-hole single nozzle in the prior art is mainly used in the production of thin slabs and continuous casting tundishes, and combined with the analysis of the flow field and temperature field characteristics inside the mold, a new type of submerged nozzle is now needed , the nozzle needs to be able to reduce the fluctuation of the liquid steel level, and reduce the impact of internal turbulence on the solidified billet shell, and ensure a certain amount of steel passing through.

Utility model content

In order to solve the above problems, the utility model re-optimizes the design by analyzing the flow field and temperature field of the submerged nozzle in the prior art, and provides a four-hole immersion nozzle for preventing turbulent flow of molten steel for pouring conventional slabs. type nozzle.

Concrete structure of the present utility model is as follows:

A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs, including a nozzle body, characterized in that:

The upper end of the nozzle body is provided with a funnel-shaped molten steel inlet;

The main body of the nozzle body is a central through-hole cylindrical tube, and a pair of molten steel upper spout holes and a pair of molten steel lower spout holes that are not at the same height are respectively provided on the tube wall of the lower part of the cylindrical tubular nozzle body. hole;

The nozzle bottom at the lowermost end of the nozzle body is in a closed state.

A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs according to the utility model is characterized in that the inner diameter of the lower end of the funnel-shaped molten steel inflow port and the cylindrical tubular shape of the central through hole The inner diameter of the nozzle body is the same.

When working, molten steel flows in from the upper end of the funnel-shaped molten steel inflow inlet, and enters the inner pipeline of the cylindrical tubular nozzle body connected to it through the lower end of the molten steel inflow inlet.

A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs according to the utility model is characterized in that the pair of molten steel upper spout holes and the pair of molten steel lower spout holes that are not at the same height Holes, specifically, the two molten steel upper spout holes and the two molten steel lower spit holes are respectively distributed in pairs, and the center point of the molten steel upper spit hole on the same side is the same as the center of the molten steel lower spit hole. The positions of the points are in a straight line along the vertical direction.

The design of the penetrating distribution in pairs reduces the static pressure of the molten steel flowing out, reduces the fluctuation of the liquid level of the crystallizer, and the center point of the upper outlet hole of the molten steel and the center point of the lower outlet hole are vertically aligned. A straight line design. , to ensure that the molten steel can meet inside the crystallizer when it flows out, and the kinetic energy is dissipated after the collision, which reduces the flow speed of the molten steel and avoids the bubbles and inclusions that are difficult to float due to the impact of the molten steel too deep.

A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs according to the utility model is characterized in that the angle between the two upper spout holes of the pair of molten steel upper spout holes and the horizontal line is It is set at -15° to -45°, and the angle between the two lower spout holes of a pair of molten steel lower spit holes and the horizontal line is set at 15° to 45°, and the angles of the spit holes on the same side are opposite.

Since the included angles of the two pairs of spit holes are opposite, when the molten steel flows out from the two pairs of spit holes, it will inevitably meet inside the mold on the extension line of the included angle, and the kinetic energy will be dissipated after the collision, reducing the flow of molten steel. The speed directly reduces the impact of molten steel flow on the narrow surface of the crystallizer. In addition, according to the size of the mold and the different working conditions on site, different angles of the utility model for pouring conventional slabs can also be selected. Four-hole submerged nozzle to prevent turbulent flow of molten steel.

A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs according to the utility model is characterized in that the four holes of the pair of molten steel upper spout holes and the pair of molten steel lower spout holes The discharge holes are all rectangular structural designs with chamfers, and the upper discharge hole is slightly larger than the lower discharge hole.

The four outlet holes are all designed in a rectangular structure with chamfers, which is beneficial to reduce the fluctuation of the crystallizer liquid level and ensure sufficient steel flow. The design of the upper spout hole is slightly larger than the lower spit hole is because the two spit holes have a certain height difference, and the kinetic energy of the molten steel flowing out of the two spit holes is also different. In order to dissipate as much steel flow energy as possible, obtain stable The molten steel flow field, so the area of the upper spit hole is larger than the area of the lower spit hole. In addition, the area ratio of the upper discharge hole and the lower discharge hole should increase with the increase of the insertion depth of the submerged nozzle.

The utility model's four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs solves the entanglement of mold slag in the four large recirculation zones of conventional double-hole nozzles for pouring slab molten steel in the prior art, Inclusions and air bubbles float up, and the impact of molten steel streams on the solidified billet shell, and overcome the problems caused by the large fluctuations in the liquid level of the mold and the impact of the molten steel in the lower part of the mold in the conventional double-hole nozzle casting in the prior art. Various unfavorable factors come, improve the surface and internal quality of the slab.

Using the four-hole submerged nozzle of the utility model for pouring conventional slabs to prevent turbulent flow of molten steel, the following beneficial effects are obtained:

1. Compared with the two-hole nozzle of the conventional slab, the four-hole submerged nozzle used for pouring the conventional slab to prevent the turbulent flow of molten steel of the utility model solves the problem of the kinetic energy of the upward molten steel flow, and the upward molten steel forms The stable crystallizer liquid level avoids the inclusion of mold slag and the growth of the billet shell, and the utility model can dissipate the kinetic energy of the molten steel flowing out from the submerged nozzle, reduce the turbulence of the molten steel, and stabilize the interior of the mold The molten steel forms a more uniform solidified slab shell and reduces the occurrence of slab cracks;

2. Using the four-hole submerged nozzle of the utility model to prevent the turbulent flow of molten steel for pouring conventional slabs, the downward energy of the downward molten steel stream is reduced by the impact of the upward stream, and there is not enough The energy brings the bubbles and inclusions to a deeper place, which is beneficial to the floating of the bubbles and inclusions, avoiding their accumulation at the front of the solidification of the slab, and improving the internal quality of the slab. Therefore, the four-hole nozzle can be used in crystallization. The interior of the device makes the molten steel more stable, thereby reducing a series of slab defects.

Description of drawings

Fig. 1 is the front view of the specific structure of the appearance of the four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs of the present invention;

Fig. 2 is a specific structural cross-sectional view along the AA direction of the four-hole submerged nozzle for pouring conventional slabs to prevent turbulent flow of molten steel according to the present invention;

Fig. 3 is a cross-sectional view of the main body of the four-hole submerged nozzle for pouring conventional slabs to prevent turbulent flow of molten steel according to the present invention;

In the figure: 1-Nozzle body, 2-Molten steel inflow inlet, 3-Molten steel upper outlet hole, 4-Molten steel lower outlet hole, 5-Nozzle bottom, a-The angle between the molten steel upper outlet hole and the horizontal line, b- The angle between the spout hole under the molten steel and the horizontal line.

Detailed ways

A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs of the present invention will be further described below in conjunction with the accompanying drawings and examples.

As shown in Figure 1 and Figure 2, in order to stabilize the molten steel flow field in the crystallizer, form a solidified and uniform slab shell, and reduce the quality defects of the cast slab, the utility model for casting conventional slabs is used in conventional slab casting. Four-hole submerged nozzle to prevent turbulent flow of molten steel. The nozzle main body 1 of the four-hole submerged nozzle is a cylindrical tubular shape with a central through hole, and the nozzle bottom 5 at the lowermost end of the nozzle body is in a closed state. A pair of molten steel upper spout holes 3 and a pair of molten steel lower spit holes 4, specifically, the two molten steel upper spit holes and the two molten steel lower spit holes are distributed in pairs opposite to each other, and the same side The positions of the center point of the upper spitting hole and the lower spitting hole of the molten steel form a straight line along the vertical direction, and the section of each spitting hole is a rectangle with chamfered corners.

The molten steel upper outlet hole 3 and the molten steel lower outlet hole 4 on the same side are designed to have a certain angle with the horizontal line, and the angles between the two outlet holes are opposite. Specifically, the angle a between the upper molten steel outlet hole and the horizontal line is -15° to -45°, the angle b between the discharge hole under the molten steel and the horizontal line is 15° to 45°. There is a certain relationship between the area of the discharge hole, the area of the main channel of the immersion nozzle and the casting speed of the casting machine. When the casting speed is high, in order to prevent the molten steel from rushing out of the discharge hole at a high speed, it will cause violent agitation of the molten steel in the mold. , must increase the area of the spit hole. There is also a certain difference in the area of the two spit holes on the same side. Because there is a certain height difference between the two spout holes, the kinetic energy of the molten steel flowing out of the two spout holes is also different. In order to dissipate the flow energy of the steel as much as possible and obtain a stable flow field of the molten steel, the spout hole on the molten steel The area of the hole is larger than that of the lower outlet hole of molten steel, and the area ratio of the upper outlet hole to the lower outlet hole should increase with the increase of the insertion depth of the submerged nozzle.

Example

First, select the four-hole submerged nozzle of the utility model with a suitable size according to the channel area of the main body of the submerged nozzle, the pulling speed of the casting machine and the insertion depth of the nozzle, and install it in place. .

As shown in Figure 1 and Figure 2, when carrying out the slab pouring work, molten steel flows from the funnel-shaped molten steel flow at the upper end of the four-hole submerged nozzle for preventing turbulent flow of molten steel used for pouring conventional slabs of the utility model The inlet 2 flows in, and then flows out from the pair of molten steel upper discharge holes 3 and the pair of molten steel lower discharge holes 4 through the pipeline connected to the nozzle body 1. The direction of the arrow in Figure 2 is the flow of molten steel. Direction, because the molten steel flowing out of the two spout holes on the same side rushes to the narrow surface of the crystallizer (not shown in the figure) at a certain speed, because the inclination angles of the two spit holes are opposite, so the two streams of molten steel will be crystallized The kinetic energy is dissipated after the collision, which reduces the speed of the molten steel stream and reduces the impact of the molten steel stream on the narrow surface of the mold. The synthetic molten steel of the two streams reaches the narrow surface of the mold at a lower speed and is divided into two backflows, upward and downward. The fluctuation after the upward reflux reaches the liquid level of the crystallizer is also reduced, which reduces the involvement of mold powder, and the small liquid level fluctuation is also conducive to the uniform formation of the primary solidified shell and reduces the occurrence of cracks. The downward flow stream greatly reduces the scope of the downflow due to the reduction in speed, which is beneficial to the floating of air bubbles and inclusions, and reduces the accumulation of inclusions at the front of the solidification of the slab.

Therefore, adopting the four-hole submerged nozzle of the utility model to prevent the turbulent flow of molten steel for pouring conventional slabs reduces the turbulent flow of molten steel inside the crystallizer from the perspective of energy dissipation and increases the stability of the liquid surface, which is not only beneficial The formation of the primary slab shell of the slab and the reduction of internal quality defects of the slab. At the same time, because the kinetic energy of the molten steel from the spout hole is dissipated, the erosion of the billet shell on the narrow surface is also greatly reduced, reducing the possibility of mold breakout, which is beneficial to the stability of production.

The four-hole submerged nozzle used for pouring conventional slabs to prevent turbulent flow of molten steel has a simple structure and low cost, and is suitable for the pouring field of conventional slabs in various iron and steel metallurgy fields, reducing the amount of steel in the slab crystallizer. The turbulent flow of the liquid stabilizes the flow field and improves the quality of the continuous casting slab.

Claims (5)

1. A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs, comprising a nozzle body (1), characterized in that: The upper end of the nozzle body (1) is provided with a funnel-shaped molten steel inlet (2); The main body of the nozzle body (1) is a cylindrical tubular shape with a central through hole, and a pair of molten steel upper spout holes (3) and A pair of molten steel lower spit holes (4); The nozzle bottom (5) at the lowermost end of the nozzle body (1) is in a closed state. 2. A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs as claimed in claim 1, characterized in that the inner diameter of the lower end of the funnel-shaped molten steel inlet (2) The inner diameter of the cylindrical nozzle body (1) of the central through hole is the same. 3. A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs as claimed in claim 1, characterized in that the outlet holes (3) on the pair of molten steel that are not at the same height and a pair of molten steel lower spout holes (4), specifically, the two molten steel upper spit holes and the two molten steel lower spit holes are distributed in pairs opposite to each other, and the center of the molten steel upper spit holes on the same side Point and the position of the central point of the outlet hole under the molten steel form a straight line along the vertical direction. 4. A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs as claimed in claim 3, characterized in that two of the upper outlet holes (3) of the pair of molten steel are The angle (a) between the discharge hole and the horizontal line is set at -15° to -45°, and the angle (b) between the two lower discharge holes of a pair of molten steel lower discharge holes (4) and the horizontal line is 15° to 45° Set, the angle between the upper spit hole and the lower spit hole on the same side is opposite. 5. A four-hole submerged nozzle for preventing turbulent flow of molten steel for pouring conventional slabs as claimed in claim 3, characterized in that, said pair of molten steel upper spout holes (3) and a pair of steel The four outlet holes of the liquid outlet hole (4) are all rectangular structural designs with chamfers, and the upper outlet hole is slightly larger than the lower outlet hole.

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