Lower injection type liquid steel injection flow protection device with jet cone annular air curtain

Abstract

The application discloses a lower injection type molten steel injection flow protection device for spraying a conical annular gas curtain, and is characterized in that: the device comprises a protection cover outer flow guide ring wall, a protection cover inner flow guide ring wall, an air inlet device and an observation unit; the protection cover outer flow guide ring wall and the protection cover inner flow guide ring wall are conical cylinder walls, and the two have the same taper; the protection cover outer flow guide ring wall and the protection cover inner flow guide ring wall are fixedly installed through a concentric shaft to form an annular gap; the annular gap is used for spraying an annular gas curtain, and the spraying direction of the annular gas curtain is directed to a top pouring gate of a central injection pipe; the air inlet device is connected with the annular gap, and after inert gas enters the annular gap, the inert gas is sprayed out of the annular gas curtain from the other end, and the spraying direction is directed to the top pouring gate of the central injection pipe. The application solves the technical problems of poor air / steel liquid stability, high sealing requirement and complex equipment structure of the existing mold casting gas atmosphere protection device.

Description

Technical Field

[0001] This invention belongs to the technical field of mold casting protective pouring equipment, specifically relating to a downward spray type molten steel injection protection device with a spray cone annular air curtain. Background Technology

[0002] Ingot casting plays an irreplaceable role in the production of high-value-added special steel and large steel ingots. High-purity, high-metallurgical-quality molten steel is crucial to the final quality of ingot-cast steel. Currently, the rapid development of secondary refining technologies such as VD and LF treatments has significantly improved the cleanliness of molten steel, controlling the total oxygen content to below 10 ppm. However, when molten steel is poured using the mainstream bottom-pouring method, a section between the bottom outlet of the ladle and the top gate of the pouring pipe is exposed to air. High-purity molten steel undergoes secondary oxidation with air during pouring, leading to aluminum loss and an increase in nitrogen, oxygen, and oxidation products in the molten steel, severely impacting the quality of ingot-cast steel. Therefore, ingot casting protective pouring technology has become a key bottleneck restricting the quality of steel ingots.

[0003] Currently, enterprises mainly employ two methods for protecting molten steel during casting: the sealing hood method and the air curtain method. The sealing hood method involves placing a sealing hood on the ingot mold in the sprue and then introducing inert gas to protect the molten steel. The air curtain method involves placing a ring pipe near the nozzle and then introducing inert gas to form an air curtain around the molten steel to isolate it from the atmosphere. Studies show that the sealing hood method is more effective than the air curtain method in preventing secondary oxidation of molten steel. However, the sealing hood method operates in a harsh environment due to contact with the high-temperature ladle or sprue, and its structure is easily damaged. It often requires vacuum evacuation before use, placing high demands on sealing technology and materials; therefore, it has not yet been widely used in practice. Furthermore, protective devices based on the sealing hood principle often incorporate one or more viewing windows on the sealing hood to overcome obstructed observation, further increasing the complexity of the equipment and manufacturing costs. The air curtain method, on the other hand, has a simple structure, is convenient to use in production, and is widely applied. However, during its use, the argon curtain is easily affected by the environment (air and molten steel flow rate, temperature, humidity, argon flow rate, etc.) and manual operation (accuracy of the direction of the inlet pipe), resulting in poor overall stability.

[0004] In summary, there is an urgent need to design a casting protection device that can effectively isolate the atmosphere and molten steel, has stable performance, and is simple in structure and easy to install and apply. Summary of the Invention

[0005] The purpose of this invention is to provide a downward spraying molten steel injection protection device with a sprayed cone-shaped annular air curtain, which solves the technical problems of poor stability of existing mold casting atmosphere protection devices in isolating the atmosphere / molten steel, high sealing requirements, and complex equipment structure.

[0006] To achieve the above objectives, the technical solution used in this invention is:

[0007] A down-spraying molten steel injection protection device with a conical annular air curtain is characterized by comprising an outer guide ring wall of a protective cover, an inner guide ring wall of the protective cover, an air inlet device, and an observation unit; the outer and inner guide ring walls of the protective cover are tapered cylindrical walls with the same taper; the outer and inner guide ring walls of the protective cover are fixed together along the same central axis to form an annular gap; the annular gap is used to spray an annular air curtain, the spray direction of which points towards the upper gate of the middle injection pipe; the air inlet device is connected to the annular gap and is used to supply inert gas into the annular gap; after the inert gas enters the annular gap, it is sprayed out from the other end of the annular air curtain, the spray direction pointing towards the upper gate of the middle injection pipe; the characteristic size of the air inlet device is more than 40 times that of the annular gap, and the pressure and velocity of the inert gas increase significantly after entering the annular gap through the air inlet device, resulting in a high spray velocity, thus making it easier to resist the impact of various high-temperature airflows during molten steel injection, and enhancing the stability of the air curtain.

[0008] Furthermore, the taper range of the outer and inner guide ring walls of the protective cover is 1-5°; the thickness of the annular gap is consistent, ranging from 0.5-3 mm; the 1-5° taper ensures that the diameter of the annular air curtain gradually expands towards the middle injection pipe, forming a tapered annular air curtain; flow field simulation calculations show that since the tapered annular air curtain has the largest diameter above the middle injection pipe, its stability against high-temperature expanding airflow is better, and it can avoid being drawn into the middle injection pipe too quickly by the molten steel, causing excessive air intake of the molten steel; the specific optimal injection angle of the air curtain is determined by the injection speed, the thickness of the annular gap, the exposed height of the molten steel (injection height), and the diameter of the middle injection pipe.

[0009] Furthermore, the outer guide ring wall of the protective cover is connected to the outer wall of the air chamber in the air intake device, and its extension direction is towards the direction of air curtain injection; the end of the outer guide ring wall of the protective cover is shorter than the end of the inner guide ring wall of the protective cover, with the shorter length ranging from 5-12 mm; according to flow field calculation, this 5-12 mm inner guide ring wall can effectively prevent the air curtain from deflecting to the inner side of the inner protective brick due to "jet adhesion".

[0010] Furthermore, the outer guide ring wall of the protective cover is fixed by an upper support brick, a telescopic support rod, and an inner guide ring wall groove. The telescopic support rod consists of a threaded screw and a nut, which is rotated to achieve extension and retraction. The threaded screw penetrates the upper support brick, and the front end of the screw located on the outer wall side of the upper support brick is flush with the end of the outer wall surface of the inner guide ring wall. The nut is located on the inner wall side of the upper support brick. The front end of the screw being flush with the end of the outer wall surface avoids disturbing the flow field near the outlet of the annular air curtain. There are a total of 6-12 telescopic support rods, evenly distributed on the upper support brick. The diameter and number of the screws are selected according to the weight of the outer guide ring wall of the protective cover to stably support the outer guide ring wall of the protective cover.

[0011] Furthermore, the inner guide ring wall groove is formed by assembling an upper protective brick and an inner protective brick; the inner diameter of the upper protective brick and the outer diameter of the inner protective brick are the same; the inner wall of the upper protective brick and the outer wall of the inner protective brick are tightly fitted together and assembled by tightening parts; the top of the upper protective brick and the inner protective brick are connected to the bottom plate of the steel ladle.

[0012] Furthermore, it also includes an air intake device, which includes an air intake channel and an air chamber; the air intake channel is a hollow cylindrical tube connected to the air chamber for conveying inert gas into the air chamber; the inner surface of the air intake channel is tangential to the inner wall of the air chamber; the central axis of the air intake channel is always located on the air intake plane; the central axis of the air intake channel forms an air intake angle with the central axis, ranging from -80° to 80°; according to flow field calculations, compared with other air intake methods, such as vertical air intake from the side of the outer wall of the air chamber, or air intake perpendicular to the upper or lower surface of the outer wall of the air chamber, tangential air intake allows the inert gas to fill the air chamber the fastest, significantly reducing the air intake volume; the tangential air intake method gives the sprayed air curtain a tangential velocity component, which is significantly beneficial to maintaining the integrity of the air curtain itself during the injection of molten steel and isolating the atmosphere; the spray angle, air intake flow rate, and air intake angle a2 of the atmosphere protection device of the present invention can be adjusted independently, thereby flexibly and accurately controlling the spray trajectory and spray velocity components of the annular air curtain.

[0013] Furthermore, the air chamber is an annular air cavity with a rounded square cross-section; the air chamber does not have an inner wall on the side near the annular slit; the top of the inner side of the air chamber is connected to the air inlet of the annular slit for conveying gas from the air chamber to the annular slit; according to flow field calculations, the combination of a single annular air chamber with a smooth inner wall and no sharp edges and a tangential air inlet method can, under the same air inlet flow rate, enable the inert gas in the air chamber to generate maximum pressure on the air inlet of the annular slit, promoting the jetting of a high-speed, uniformly thick air curtain.

[0014] Furthermore, it also includes an observation unit, which comprises an observation hood, a pressure monitor, and an oxygen concentration detector. The observation hood is located 5-10 cm below the lower edge of the upper support brick and is placed directly on the upper end face of the middle injection pipe. The inner diameter of the observation hood is 0-30 cm larger than the outer diameter of the upper protective brick. The observation hood is made of high-temperature resistant tempered glass. The pressure monitor and oxygen concentration detector are placed and fixed by drilling holes in the observation hood. The pressure monitor is located below the oxygen concentration detector. The pressure monitor is used to detect the rationality of the argon flow rate so as to adjust the argon inlet flow rate at any time. The oxygen concentration detector detects the protection effect in real time. The drilling height does not exceed half the height of the protective hood. The low drilling height can ensure that the operating temperature of the pressure monitor and oxygen concentration detector is not too high, and at the same time, the pressure monitor detects a relatively undisturbed flow field, resulting in more accurate data. The protective hood, made of tempered glass, is not only heat resistant but also provides a 360° unobstructed observation field. Moreover, its preparation is simpler than that of a sealed hood with an observation window, and there are no sealing requirements.

[0015] The technical effects of this invention include:

[0016] This invention constructs an annular slit structure, connecting the slits to an annular gas chamber several times its size. Simultaneously, it employs a rapid tangential air intake method into the gas chambers to spray a high-speed, uniformly thick, and tightly surrounding conical annular gas curtain around the molten steel. The resulting conical annular gas curtain is highly stable during the high-temperature molten steel injection process, effectively isolating the molten steel from contact with the atmosphere and completely preventing secondary oxidation. The injection protection device of this invention is simple in structure design, processing, and installation, requires no special sealing, and incorporates a pressure monitor and oxygen concentration detector with tempered glass as an observation window. This allows for real-time monitoring of argon flow rate and oxygen concentration, enabling timely adjustment of the argon intake flow rate to maximize the protective effect. Attached Figure Description

[0017] Figure 1a This is a cross-sectional structural diagram of the present invention;

[0018] Figure 1b This is a top view of Figure 1;

[0019] Figure 2 This is a three-dimensional structural diagram of the present invention;

[0020] Figure 3 This is a top view of Figure 1 of the present invention;

[0021] Figure 4 For the present invention Figure 3 The right view, showing only a portion of the cells;

[0022] Figure 5 This is a schematic cross-sectional view of the outer guide ring wall 1, the inner guide ring wall 2, the annular gap 3, the annular gap air inlet 4, and the air curtain outlet 5 of the present invention.

[0023] The diagram is marked as follows:

[0024] 1. Outer guide ring wall of the protective cover; 2. Inner guide ring wall of the protective cover; 3. Annular gap; 4. Air inlet of the annular gap; 5. Air curtain outlet; 6. Upper support brick; 7. Telescopic support rod; 8. Upper protective brick; 9. Inner guide ring wall groove; 10. Inner protective brick; 11. Air intake device; 12. Air intake channel; 13. Air chamber; 14. Observation unit; 15. Observation cover; 16. Pressure monitor; 17. Oxygen concentration detector; Detailed Implementation

[0025] The following description fully illustrates specific embodiments of the invention to enable those skilled in the art to practice and reproduce them.

[0026] Example 1

[0027] Based on the detection and statistical analysis of oxygen concentration in the inert atmosphere generated by the early protection device at the molten steel pouring site, it was found that when the molten steel pouring diameter is 45-50 cm, the pouring height is greater than 35 cm, and the pouring velocity is greater than 52 kg / s, the inert gas curtain is easily destroyed (the oxygen concentration rises rapidly within a few seconds). However, when the molten steel pouring diameter is less than 42 cm, the pouring height is 20-30 cm, and the pouring velocity is less than 44 kg / s, the inert gas curtain is maintained for a longer period. This embodiment is applicable to the working condition of molten steel pouring diameter 35 cm, pouring height 25 cm, and molten steel pouring velocity 40 kg / s. Under these conditions, the entrainment effect of the molten steel on the gas curtain is weak, the exposed distance required for protection by the sprayed annular gas curtain is short, and the impact of the air discharged after the molten steel enters the middle pouring pipe on the annular gas curtain is low.

[0028] like Figures 1a-5 As shown, the present invention discloses a downward-spraying molten steel injection protection device with a sprayed conical annular air curtain, comprising an outer guide ring wall 1, an inner guide ring wall 2, and an air inlet device 11. The outer guide ring wall 1 and the inner guide ring wall 2 have the same taper and are fixed along the central axis Z1 to form an annular gap 3. The taper range of the outer guide ring wall 1 and the inner guide ring wall 2 is 1-5°, preferably 1° in this embodiment, as this preferred taper is suitable for the low injection velocity in this embodiment. The low injection velocity results in a weak entrainment effect on the air curtain, therefore there is no need to increase the spray angle to resist severe air intake of the molten steel caused by excessively fast entrainment. The air inlet device 11 is used to supply air to the annular gap 3. The annular gap 3 is used to spray an annular air curtain downwards towards the central injection pipe to enclose the injected molten steel and isolate it from the atmosphere. The thickness L1 of the annular gap 3 is uniform, ranging from 0.5-3mm, preferably 0.5mm in this embodiment. In this embodiment, the thickness L1 of the preferred annular gap 3 is sufficient to maintain the integrity of the air curtain while reducing the air intake flow rate when the air in the injection pipe is discharged during the molten steel injection.

[0029] The end of the outer guide ring wall 1 of the protective cover is shorter than the end of the inner guide ring wall 2 of the protective cover, with a difference in length L2, ranging from 5-12 mm, and preferably 5 mm in this embodiment. Flow field calculations show that this 5 mm section of the inner guide ring wall effectively prevents the air curtain from deflecting inwards towards the inner protective brick due to "jet adhesion." The inner guide ring wall 2 of the protective cover is fixed by the upper support brick 6, the telescopic support rod 7, and the inner guide ring wall groove 9. The telescopic support rod 7 is a threaded screw and nut, which extends and retracts by rotating the nut. Preferably, there are 8 telescopic support rods 7, evenly distributed on the upper support brick 6. The inner guide ring wall groove 9 is formed by assembling the upper protective brick 8 and the inner protective brick 10. The inner wall of the upper protective brick 8 is tightly fitted to the outer wall of the inner protective brick 10, and assembly is completed by tightening parts.

[0030] In this embodiment, the inner surface of the air intake channel 12 is tangent to the inner wall of the air chamber 13, and there is an air intake angle α2 between the central axis Z2 and the central axis Z1 of the air intake channel. Figure 4 The range of a2 is -80° to 80°, with 80° being preferred in this embodiment. Flow field calculations show that as the inlet angle increases from 0° to 10°, the jet velocity of the annular slit 3 gradually decreases. The preferred taper and inlet angle of this embodiment ensure a low-velocity annular air curtain. This embodiment also includes an observation unit 14, which comprises an observation hood 15, a pressure monitor 16, and an oxygen concentration detector 17. Preferably, the observation hood 15 is located 5 cm below the lower edge of the upper support brick 6, matching a smaller injection height, and is placed directly on the upper end face of the middle injection pipe. The inner diameter of the observation hood is 15 cm larger than the outer diameter of the upper protective brick 8, matching a smaller injection velocity. The pressure monitor 16 and the oxygen concentration detector 17 are placed and fixed by drilling holes in the observation hood 15. The pressure monitor 16 is located below the oxygen concentration detector 17. The pressure monitor 16 and the oxygen concentration detector 17 use existing high-temperature resistant products.

[0031] Example 2

[0032] This embodiment is applicable to a steel molten injection diameter of 50cm, an injection height of 40cm, and a steel molten injection velocity of 60 kg / s. Under these conditions, the injected steel molten material has a strong entrainment effect on the air curtain, and the exposed distance to be protected by the sprayed annular air curtain is long. Furthermore, the air discharged after the injected steel molten material enters the central injection pipe has a strong impact on the annular air curtain.

[0033] The basic content of this embodiment is the same as that of Embodiment 1, except that: the inner guide ring wall 2 of the protective cover forms a spray angle with the central axis Z1, the spray angle range is 1-5°, and 3° is preferred in this embodiment. The preferred spray angle is suitable for the working conditions of large injection velocity and large injection diameter in this embodiment. Increasing the spray angle can appropriately resist the strong entrainment effect of the injected molten steel. The outer guide ring wall 1 and the inner guide ring wall 2 of the protective cover form an annular gap 3, the thickness L1 of the annular gap 3 is the same, the thickness range is 0.5-3mm, and 3mm is preferred in this embodiment. Through system flow field calculation, it was found that the larger the thickness L1 of the annular gap 3, the stronger the ability to resist exhaust impact. At the same time, the larger the thickness of the annular air curtain, the faster the air curtain is entrained by the molten steel and forms an oxygen-free inert gas environment. The end of the outer guide ring wall 1 of the protective cover is shorter than the end of the inner guide ring wall 2 of the protective cover, the difference in length range is 5-12mm, and 5mm is preferred in this embodiment. Based on multiphase flow field calculations, the 5mm inner guide ring wall can effectively prevent the air curtain from deflecting inwards towards the inner side of the protective brick due to "jet adhesion". In this embodiment, the inner surface of the air intake channel 12 is tangent to the inner wall of the air chamber 13, and there is an air intake angle α2 between the central axis Z2 and the central axis Z1 of the air intake channel. Figure 4The range of a2 is -80° to 80°, and 0° is preferred in this embodiment. This preferred inlet angle ensures that the air chamber is quickly filled with inert gas, the inlet pressure of the annular slit 3 is high, and the injection speed of the annular air curtain is high enough, which is suitable for working conditions with large annular slit thickness and high injection height.

[0034] Example 3

[0035] Based on the detection and statistical analysis of oxygen concentration in the inert atmosphere generated by the early protection device at the molten steel pouring site, it was found that when the molten steel pouring diameter is 45-50 cm, the pouring height is greater than 35 cm, and the pouring velocity is greater than 52 kg / s, the inert gas curtain is easily destroyed (the oxygen concentration rises rapidly within a few seconds). However, when the molten steel pouring diameter is less than 42 cm, the pouring height is 20-30 cm, and the pouring velocity is less than 44 kg / s, the inert gas curtain is maintained for a longer period. This embodiment is applicable to the working condition of molten steel pouring diameter 35 cm, pouring height 25 cm, and molten steel pouring velocity 40 kg / s. Under these conditions, the entrainment effect of the molten steel on the gas curtain is weak, the exposed distance required for protection by the sprayed annular gas curtain is short, and the impact of the air discharged after the molten steel enters the middle pouring pipe on the annular gas curtain is low.

[0036] like Figures 1a-5 As shown, the present invention discloses a downward-spraying molten steel injection protection device with a sprayed conical annular air curtain, comprising an outer guide ring wall 1, an inner guide ring wall 2, and an air inlet device 11. The outer guide ring wall 1 and the inner guide ring wall 2 have the same taper and are fixed along the central axis Z1 to form an annular gap 3. The taper range of the outer guide ring wall 1 and the inner guide ring wall 2 is 1-5°, preferably 2° in this embodiment. This preferred taper is suitable for the low injection velocity in this embodiment. The low injection velocity results in a weak entrainment effect on the air curtain, thus eliminating the need to increase the spray angle to resist severe air intake by the molten steel caused by excessively rapid entrainment. The air inlet device 11 is used to supply air to the annular gap 3. The annular gap 3 is used to spray an annular air curtain downwards towards the central injection pipe to enclose the injected molten steel and isolate it from the atmosphere. The thickness L1 of the annular gap 3 is uniform, ranging from 0.5-3mm, preferably 0.5mm in this embodiment. In this embodiment, the thickness L1 of the preferred annular gap 3 is sufficient to maintain the integrity of the air curtain while reducing the air intake flow rate when the air in the injection pipe is discharged during the molten steel injection.

[0037] The end of the outer guide ring wall 1 of the protective cover is shorter than the end of the inner guide ring wall 2 of the protective cover, with a difference in length L2, ranging from 5-12 mm, and preferably 5 mm in this embodiment. Flow field calculations show that this 5 mm section of the inner guide ring wall effectively prevents the air curtain from deflecting inwards towards the inner protective brick due to "jet adhesion." The inner guide ring wall 2 of the protective cover is fixed by the upper support brick 6, the telescopic support rod 7, and the inner guide ring wall groove 9. The telescopic support rod 7 is a threaded screw and nut, which extends and retracts by rotating the nut. Preferably, there are 8 telescopic support rods 7, evenly distributed on the upper support brick 6. The inner guide ring wall groove 9 is formed by assembling the upper protective brick 8 and the inner protective brick 10. The inner wall of the upper protective brick 8 is tightly fitted to the outer wall of the inner protective brick 10, and assembly is completed by tightening parts.

[0038] In this embodiment, the inner surface of the air intake channel 12 is tangent to the inner wall of the air chamber 13, and there is an air intake angle α2 between the central axis Z2 and the central axis Z1 of the air intake channel. Figure 4 The range of a2 is -80° to 80°, with 60° being preferred in this embodiment. Flow field calculations show that as the inlet angle increases from 0° to 10°, the jet velocity of the annular slit 3 gradually decreases. The preferred taper and inlet angle of this embodiment ensure a low-velocity annular air curtain. This embodiment also includes an observation unit 14, which comprises an observation hood 15, a pressure monitor 16, and an oxygen concentration detector 17. Preferably, the observation hood 15 is located 5 cm below the lower edge of the upper support brick 6, matching a smaller injection height, and is placed directly on the upper end face of the middle injection pipe. The inner diameter of the observation hood is 15 cm larger than the outer diameter of the upper protective brick 8, matching a smaller injection velocity. The pressure monitor 16 and oxygen concentration detector 17 are placed and fixed by drilling holes in the observation hood 15. The pressure monitor 16 is located below the oxygen concentration detector 17. The pressure monitor 16 and oxygen concentration detector 17 use existing high-temperature resistant products.

[0039] Example 4

[0040] This embodiment is applicable to a steel molten injection diameter of 50cm, an injection height of 40cm, and a steel molten injection velocity of 60 kg / s. Under these conditions, the injected steel molten material has a strong entrainment effect on the air curtain, and the exposed distance to be protected by the sprayed annular air curtain is long. Furthermore, the air discharged after the injected steel molten material enters the central injection pipe has a strong impact on the annular air curtain.

[0041] The basic content of this embodiment is the same as that of embodiment 1, except that: the inner guide ring wall 2 of the protective cover forms a spray angle with the central axis Z1, the spray angle range is 1-5°, and 4° is preferred in this embodiment. The preferred spray angle is suitable for the working conditions of large injection velocity and large injection diameter in this embodiment. Increasing the spray angle can appropriately resist the strong entrainment effect of the injected molten steel. The outer guide ring wall 1 and the inner guide ring wall 2 of the protective cover form an annular gap 3, the thickness L1 of the annular gap 3 is the same, the thickness range is 0.5-3mm, and 3mm is preferred in this embodiment. According to the system flow field calculation, it is found that the larger the thickness L1 of the annular gap 3, the stronger the ability to resist exhaust impact. At the same time, the larger the thickness of the annular air curtain, the faster the air curtain is entrained by the molten steel around the molten steel and forms an oxygen-free inert gas environment. The end of the outer guide ring wall 1 of the protective cover is shorter than the end of the inner guide ring wall (2) of the protective cover, the difference in length range is 5-12mm, and 5mm is preferred in this embodiment. Based on multiphase flow field calculations, the 5mm inner guide ring wall can effectively prevent the air curtain from deflecting inwards towards the inner side of the protective brick due to "jet adhesion". In this embodiment, the inner surface of the air intake channel 12 is tangent to the inner wall of the air chamber 13, and there is an air intake angle α2 between the central axis Z2 and the central axis Z1 of the air intake channel. Figure 4 The range of a2 is -80° to 80°, and 0° is preferred in this embodiment. This preferred inlet angle ensures that the air chamber is quickly filled with inert gas, the inlet pressure of the annular slit 3 is high, and the injection speed of the annular air curtain is high enough, which is suitable for working conditions with large annular slit thickness and high injection height.

[0042] Example 5

[0043] Based on the detection and statistical analysis of oxygen concentration in the inert atmosphere generated by the early protection device at the molten steel pouring site, it was found that when the molten steel pouring diameter is 45-50 cm, the pouring height is greater than 35 cm, and the pouring velocity is greater than 52 kg / s, the inert gas curtain is easily destroyed (the oxygen concentration rises rapidly within a few seconds). However, when the molten steel pouring diameter is less than 42 cm, the pouring height is 20-30 cm, and the pouring velocity is less than 44 kg / s, the inert gas curtain is maintained for a longer period. This embodiment is applicable to the working condition of molten steel pouring diameter 35 cm, pouring height 25 cm, and molten steel pouring velocity 40 kg / s. Under these conditions, the entrainment effect of the molten steel on the gas curtain is weak, the exposed distance required for protection by the sprayed annular gas curtain is short, and the impact of the air discharged after the molten steel enters the middle pouring pipe on the annular gas curtain is low.

[0044] like Figures 1a-3As shown, the present invention discloses a downward-spraying molten steel injection protection device with a sprayed conical annular air curtain, comprising an outer guide ring wall 1, an inner guide ring wall 2, and an air inlet device 11. The outer guide ring wall 1 and the inner guide ring wall 2 have the same taper and are fixed along the central axis Z1 to form an annular gap 3. The taper range of the outer guide ring wall 1 and the inner guide ring wall 2 is 1-5°, preferably 5° in this embodiment, as this preferred taper is suitable for the low injection velocity in this embodiment. The low injection velocity results in a weak entrainment effect on the air curtain, therefore there is no need to increase the spray angle to resist severe air intake of the molten steel caused by excessively fast entrainment. The air inlet device 11 is used to supply air to the annular gap 3. The annular gap 3 is used to spray an annular air curtain downwards towards the central injection pipe to enclose the injected molten steel and isolate it from the atmosphere. The thickness L1 of the annular gap 3 is uniform, ranging from 0.5-3mm, preferably 0.5mm in this embodiment. In this embodiment, the thickness L1 of the preferred annular gap 3 is sufficient to maintain the integrity of the air curtain while reducing the air intake flow rate when the air in the injection pipe is discharged during the molten steel injection.

[0045] The end of the outer guide ring wall 1 of the protective cover is shorter than the end of the inner guide ring wall 2 of the protective cover, with a difference in length L2, ranging from 5-12 mm, and preferably 5 mm in this embodiment. Flow field calculations show that this 5 mm section of the inner guide ring wall effectively prevents the air curtain from deflecting inwards towards the inner protective brick due to "jet adhesion." The inner guide ring wall 2 of the protective cover is fixed by the upper support brick 6, the telescopic support rod 7, and the inner guide ring wall groove 9. The telescopic support rod 7 is a threaded screw and nut, which extends and retracts by rotating the nut. Preferably, there are 8 telescopic support rods 7, evenly distributed on the upper support brick 6. The inner guide ring wall groove 9 is formed by assembling the upper protective brick 8 and the inner protective brick 10. The inner wall of the upper protective brick 8 is tightly fitted to the outer wall of the inner protective brick 10, and assembly is completed by tightening parts.

[0046] In this embodiment, the inner surface of the air intake channel 12 is tangent to the inner wall of the air chamber 13, and there is an air intake angle α2 between the central axis Z2 and the central axis Z1 of the air intake channel. Figure 4The range of a2 is -80° to 80°, with 50° being preferred in this embodiment. Flow field calculations show that as the inlet angle increases from 0° to 10°, the jet velocity of the annular slit 3 gradually decreases. The preferred taper and inlet angle of this embodiment ensure a low-velocity annular air curtain. This embodiment also includes an observation unit 14, which comprises an observation hood 15, a pressure monitor 16, and an oxygen concentration detector 17. Preferably, the observation hood 15 is located 5 cm below the lower edge of the upper support brick 6, matching a smaller injection height, and is placed directly on the upper end face of the middle injection pipe. The inner diameter of the observation hood is 15 cm larger than the outer diameter of the upper protective brick 8, matching a smaller injection velocity. The pressure monitor 16 and the oxygen concentration detector 17 are placed and fixed by drilling holes in the observation hood 15. The pressure monitor 16 is located below the oxygen concentration detector 17. The pressure monitor 16 and the oxygen concentration detector 17 use existing high-temperature resistant products.

[0047] Example 6

[0048] This embodiment is applicable to a steel molten injection diameter of 50cm, an injection height of 40cm, and a steel molten injection velocity of 60 kg / s. Under these conditions, the injected steel molten material has a strong entrainment effect on the air curtain, and the exposed distance to be protected by the sprayed annular air curtain is long. Furthermore, the air discharged after the injected steel molten material enters the central injection pipe has a strong impact on the annular air curtain.

[0049] The basic content of this embodiment is the same as that of Embodiment 1, except that: the inner guide ring wall 2 of the protective cover forms a spray angle with the central axis Z1, the spray angle range is 1-5°, and 1° is preferred in this embodiment. The preferred spray angle is suitable for the working conditions of large injection velocity and large injection diameter in this embodiment. Increasing the spray angle can appropriately resist the strong entrainment effect of the injected molten steel. The outer guide ring wall 1 and the inner guide ring wall 2 of the protective cover form an annular gap 3, the thickness L1 of the annular gap 3 is the same, the thickness range is 0.5-3mm, and 3mm is preferred in this embodiment. Through system flow field calculation, it was found that the larger the thickness L1 of the annular gap 3, the stronger the ability to resist exhaust impact. At the same time, the larger the thickness of the annular air curtain, the faster the air curtain is entrained by the molten steel and forms an oxygen-free inert gas environment. The end of the outer guide ring wall 1 of the protective cover is shorter than the end of the inner guide ring wall 2 of the protective cover, the difference in length range is 5-12mm, and 5mm is preferred in this embodiment. Based on multiphase flow field calculations, the 5mm inner guide ring wall can effectively prevent the air curtain from deflecting inwards towards the inner side of the protective brick due to "jet adhesion". In this embodiment, the inner surface of the air intake channel 12 is tangent to the inner wall of the air chamber 13, and there is an air intake angle α2 between the central axis Z2 and the central axis Z1 of the air intake channel. Figure 4The range of a2 is -80° to 80°, and in this embodiment, -10° is preferred. This preferred inlet angle ensures that the gas chamber is quickly filled with inert gas, the inlet pressure of the annular slit 3 is high, and the injection speed of the annular air curtain is high enough, which is suitable for working conditions with large annular slit thickness and high injection height.

[0050] Example 7

[0051] Based on the detection and statistical analysis of oxygen concentration in the inert atmosphere generated by the early protection device at the molten steel pouring site, it was found that when the molten steel pouring diameter is 45-50 cm, the pouring height is greater than 35 cm, and the pouring velocity is greater than 52 kg / s, the inert gas curtain is easily destroyed (the oxygen concentration rises rapidly within a few seconds). However, when the molten steel pouring diameter is less than 42 cm, the pouring height is 20-30 cm, and the pouring velocity is less than 44 kg / s, the inert gas curtain is maintained for a longer period. This embodiment is applicable to the working condition of molten steel pouring diameter 35 cm, pouring height 25 cm, and molten steel pouring velocity 40 kg / s. Under these conditions, the entrainment effect of the molten steel on the gas curtain is weak, the exposed distance required for protection by the sprayed annular gas curtain is short, and the impact of the air discharged after the molten steel enters the middle pouring pipe on the annular gas curtain is low.

[0052] like Figures 1a-5 As shown, the present invention discloses a downward-spraying molten steel injection protection device with a sprayed conical annular air curtain, comprising an outer guide ring wall 1, an inner guide ring wall 2, and an air inlet device 11. The outer guide ring wall 1 and the inner guide ring wall 2 have the same taper and are fixed along the central axis Z1 to form an annular gap 3. The taper range of the outer guide ring wall 1 and the inner guide ring wall 2 is 1-5°, preferably 5° in this embodiment, as this preferred taper is suitable for the low injection velocity in this embodiment. The low injection velocity results in a weak entrainment effect on the air curtain, therefore there is no need to increase the spray angle to resist severe air intake of the molten steel caused by excessively fast entrainment. The air inlet device 11 is used to supply air to the annular gap 3. The annular gap 3 is used to spray an annular air curtain downwards towards the central injection pipe to enclose the injected molten steel and isolate it from the atmosphere. The thickness L1 of the annular gap 3 is uniform, ranging from 0.5-3mm, preferably 0.5mm in this embodiment. In this embodiment, the thickness L1 of the preferred annular gap 3 is sufficient to maintain the integrity of the air curtain while reducing the air intake flow rate when the air in the injection pipe is discharged during the molten steel injection.

[0053] The end of the outer guide ring wall 1 of the protective cover is shorter than the end of the inner guide ring wall 2 of the protective cover, with a difference in length L2, ranging from 5-12 mm, and preferably 5 mm in this embodiment. Flow field calculations show that this 5 mm section of the inner guide ring wall effectively prevents the air curtain from deflecting inwards towards the inner protective brick due to "jet adhesion." The inner guide ring wall 2 of the protective cover is fixed by the upper support brick 6, the telescopic support rod 7, and the inner guide ring wall groove 9. The telescopic support rod 7 is a threaded screw and nut, which extends and retracts by rotating the nut. Preferably, there are 8 telescopic support rods 7, evenly distributed on the upper support brick 6. The inner guide ring wall groove 9 is formed by assembling the upper protective brick 8 and the inner protective brick 10. The inner wall of the upper protective brick 8 is tightly fitted to the outer wall of the inner protective brick 10, and assembly is completed by tightening parts.

[0054] In this embodiment, the inner surface of the air intake channel 12 is tangent to the inner wall of the air chamber 13, and there is an air intake angle α2 between the central axis Z2 and the central axis Z1 of the air intake channel. Figure 4 The range of a2 is -80° to 80°, with -70° being preferred in this embodiment. Flow field calculations show that as the inlet angle increases from 0° to 10°, the jet velocity of the annular slit 3 gradually decreases. The preferred taper and inlet angle of this embodiment ensure a low-velocity annular air curtain. This embodiment also includes an observation unit 14, which comprises an observation hood 15, a pressure monitor 16, and an oxygen concentration detector 17. Preferably, the observation hood 15 is located 5 cm below the lower edge of the upper support brick 6, matching a smaller injection height, and is placed directly on the upper end face of the middle injection pipe. The inner diameter of the observation hood is 15 cm larger than the outer diameter of the upper protective brick 8, matching a smaller injection velocity. The pressure monitor 16 and the oxygen concentration detector 17 are placed and fixed by drilling holes in the observation hood 15. The pressure monitor 16 is located below the oxygen concentration detector 17. The pressure monitor 16 and the oxygen concentration detector 17 use existing high-temperature resistant products.

[0055] Example 8

[0056] This embodiment is applicable to a steel molten injection diameter of 50cm, an injection height of 40cm, and a steel molten injection velocity of 60 kg / s. Under these conditions, the injected steel molten material has a strong entrainment effect on the air curtain, and the exposed distance to be protected by the sprayed annular air curtain is long. Furthermore, the air discharged after the injected steel molten material enters the central injection pipe has a strong impact on the annular air curtain.

[0057] The basic content of this embodiment is the same as that of Embodiment 1, except that: the inner guide ring wall 2 of the protective cover forms a spray angle with the central axis Z1, the spray angle range is 1-5°, and 3° is preferred in this embodiment. The preferred spray angle is suitable for the working conditions of large injection velocity and large injection diameter in this embodiment. Increasing the spray angle can appropriately resist the strong entrainment effect of the injected molten steel. The outer guide ring wall 1 and the inner guide ring wall 2 of the protective cover form an annular gap 3, the thickness L1 of the annular gap 3 is the same, the thickness range is 0.5-3mm, and 3mm is preferred in this embodiment. Through system flow field calculation, it was found that the larger the thickness L1 of the annular gap 3, the stronger the ability to resist exhaust impact. At the same time, the larger the thickness of the annular air curtain, the faster the air curtain is entrained by the molten steel and forms an oxygen-free inert gas environment. The end of the outer guide ring wall 1 of the protective cover is shorter than the end of the inner guide ring wall 2 of the protective cover, the difference in length range is 5-12mm, and 5mm is preferred in this embodiment. Based on multiphase flow field calculations, the 5mm inner guide ring wall can effectively prevent the air curtain from deflecting inwards towards the inner side of the protective brick due to "jet adhesion". In this embodiment, the inner surface of the air intake channel 12 is tangent to the inner wall of the air chamber 13, and there is an air intake angle α2 between the central axis Z2 and the central axis Z1 of the air intake channel. Figure 4 The range of a2 is -80° to 80°, and -80° is preferred in this embodiment. This preferred inlet angle ensures that the gas chamber is quickly filled with inert gas, the inlet pressure of the annular slit 3 is high, and the injection speed of the annular air curtain is high enough, which is suitable for working conditions with large annular slit thickness and high injection height.

[0058] The on-site pouring protection steps are as follows:

[0059] 1. Before loading molten steel into the ladle, install the inner protective brick 10 and the upper protective brick 8 around the ladle's drain outlet by tightening them. Then, install the upper support brick 6 with the telescopic rod 7 at the lower end of the upper protective brick 8 by tightening it. After installing the upper support brick 6, adjust the length of the end of the telescopic rod 7 to the preset value.

[0060] 2. Before packing the molten steel into the steel package, place the inner guide ring wall 2 of the protective cover between the inner guide ring wall slot 9 and the telescopic rod 7 to complete the installation. Then, install the gas chamber 13 and the outer guide ring wall 1 of the protective cover onto the lower end of the upper protective brick 8 by tightening. The inner guide ring wall 2 and the outer guide ring wall 1 of the protective cover have the same axis of rotation. After the gas chamber 13 is installed, connect the air inlet channel 12 tangentially. Fill the gap between the air inlet channel 12 and the air inlet hole of the gas chamber 13 with refractory fiber material and fix the air inlet angle a2.

[0061] 3. After the ladle car arrives at the pouring position, maneuver the ladle car to lower the ladle, and then place an observation hood on the upper end face of the inlet pipe. After placement, argon gas is introduced through the air inlet channel 12 to form an annular gas curtain. Then the molten steel begins to be poured, while observing the data from the oxygen detector 16 and pressure monitor 17 to adjust the air inlet flow rate as needed.

[0062] 4. After completing the pouring at this pouring position, operate the ladle car to the next pouring position and repeat step 3 to complete the pouring at this pouring position. Different pouring heights are compensated by adjusting the air intake flow rate, which is obtained through experiments and flow field simulation.

[0063] 5. After all pouring stations are completed, turn off the argon gas switch. After the ladle car reaches the dismantling position, remove the injection protection device.

[0064] The terminology used in this invention is descriptive and exemplary, not restrictive. Since this invention can be embodied in many forms without departing from the spirit or essence of the technical solution, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A downward-spraying molten steel injection protection device with a sprayed conical annular air curtain, characterized in that, include: The protective cover consists of an outer guide ring wall (1), an inner guide ring wall (2), an air intake device (11), and an observation unit (14). The outer guide ring wall (1) and the inner guide ring wall (2) are tapered cylindrical walls with the same taper. The taper range of the outer guide ring wall (1) and the inner guide ring wall (2) is 1-5°. The outer guide ring wall (1) and the inner guide ring wall (2) are fixed by the central axis (Z1) to form an annular gap (3). The thickness (L1) of the annular gap (3) is the same, ranging from 0.5-3mm. The annular gap (3) is used to spray an annular air curtain, and the spray direction of the annular air curtain is towards the upper gate of the injection pipe. The outer guide ring wall (1) is connected to the air intake device (11). The air intake device (11) is used to supply inert gas into the annular gap (3) and extends in the direction of the air curtain injection. It includes an air intake channel (12) and an air chamber (13). The air intake channel (12) is a hollow cylindrical tube connected to the air chamber (13) and is used to supply inert gas into the air chamber (13). The inner surface of the air intake channel (12) is tangent to the inner wall of the air chamber (13). The central axis (Z2) of the air intake channel (12) is located on the air intake plane (P1). The central axis (Z2) of the air intake channel and the central axis (Z1) form an air intake angle (a2), which ranges from -80° to 80°. The end of the outer guide ring wall (1) of the protective cover is longer than the end of the inner guide ring wall (2) of the protective cover, and the distance (L2) between the ends ranges from 5 to 12. mm; The observation unit (14) includes an observation cover (15), a pressure monitor (16) and an oxygen concentration detector (17). The observation cover (15) is located 5-10 cm below the lower edge of the upper support brick (6). The inner diameter of the observation cover (15) is 0-30 cm larger than the outer diameter of the upper protective brick. The observation cover (15) is made of high-temperature resistant tempered glass. The pressure monitor (16) and the oxygen concentration detector (17) are placed and fixed by drilling holes in the observation cover. The drilling height does not exceed half the height of the protective cover. The pressure monitor (16) is located below the oxygen concentration detector (17).

2. The downward-spraying molten steel injection protection device with a jetting conical annular air curtain according to claim 1, characterized in that, The inner guide ring wall (2) of the protective cover is fixed by the upper support brick (6), the telescopic support rod (7) and the inner guide ring wall groove (9).

3. The downward-spraying molten steel injection protection device with a jetting conical annular air curtain according to claim 2, characterized in that, The telescopic support rod (7) consists of a threaded screw and a nut, which can be extended or retracted by rotating the nut; the threaded screw penetrates the upper support brick (6), and the front end of the screw located on the outer wall side of the upper support brick (6) is flush with the inner side of the annular gap, and the nut is located on the inner wall side of the upper support brick (6); there are a total of 6-12 telescopic support rods (7), which are evenly distributed on the upper support brick (6).

4. The downward-spraying molten steel injection protection device with a jetting conical annular air curtain according to claim 2, characterized in that, The thickness (L3) of the inner guide ring wall groove (9) is twice the thickness (L1) of the annular gap (3); the inner guide ring wall groove (9) is formed by assembling the upper protective brick (8) and the inner protective brick (10); the inner diameter of the upper protective brick (8) and the outer diameter of the inner protective brick (10) are the same; the inner wall of the upper protective brick (8) and the outer wall of the inner protective brick (10) are tightly fitted to complete the assembly; the top of the upper protective brick (8) and the inner protective brick (10) are connected to the bottom plate of the steel ladle.

5. The downward-spraying molten steel injection protection device with a jetting conical annular air curtain according to claim 1, characterized in that, The air chamber (13) is an annular air cavity with a square cross-section and the four corners of the square cross-section are rounded. The air chamber (13) does not have an inner wall on the side near the annular gap. The top of the inner side of the air chamber (13) is connected to the air inlet (4) of the annular gap for conveying gas from the air chamber (13) to the annular gap.

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