Downward spraying type molten steel flow injection protection device for spraying taper annular air curtain

Abstract

The invention discloses a downward spraying type molten steel flow injection protection device for spraying a taper annular air curtain. The downward spraying type molten steel flow injection protection device is characterized by comprising a protection cover outer flow guide annular wall, a protection cover inner flow guide annular wall, an air inlet device and an observation unit; the protective cover outer flow guide ring wall and the protective cover inner flow guide ring wall are cylinder walls with conicity, and the conicity of the two cylinder walls is the same. The protection cover outer flow guide ring wall and the protection cover inner flow guide ring wall are installed and fixed through the same center shaft to form an annular gap. The annular gap is used for spraying an annular air curtain, and the spraying direction of the annular air curtain points to an upper sprue of the center injection pipe; the gas inlet device is connected with the annular gap, inert gas enters the annular gap and then is jetted out of the annular gas curtain from the other end, and the jetting direction points to the upper sprue of the center injection pipe. The die casting atmosphere protection device solves the technical problems that an existing die casting atmosphere protection device is poor in atmosphere / molten steel isolation stability, high in sealing requirement and complex in equipment structure.

Description

Technical Field

[0001] The invention belongs to the technical field of die casting protection pouring equipment, and in particular relates to a downward spraying type molten steel injection protection device for spraying a conical annular air curtain. Background Art

[0002] Die casting has irreplaceable importance in the production of high value-added special steel and large ingots. High-purity, high metallurgical quality molten steel is crucial to the final quality of die-cast ingots. Currently, secondary refining technologies such as VD and LF treatment are developing rapidly, which has greatly improved the cleanliness of molten steel, and the total oxygen content of molten steel can be controlled below 10ppm. However, when the molten steel is poured using the mainstream down-pouring method, there is a section between the bottom water inlet of the ladle and the upper pouring port of the center pouring pipe that is exposed to the air. During the pouring process, the high-purity molten steel undergoes secondary oxidation with the air, resulting in aluminum loss, and the nitrogen, oxygen content and oxidation products in the molten steel increase, seriously affecting the quality of the die-cast ingots. Therefore, die casting protective pouring technology has become a key bottleneck restricting the quality of steel ingots.

[0003] At present, enterprises mainly adopt two methods of mold casting protection, namely the sealing cover method and the air curtain method. The sealing cover method sets a sealing cover on the ingot mold of the middle pouring pipe, and then introduces inert gas to protect the injection flow. The air curtain method sets a ring pipe near the water inlet, and then passes inert gas around the injection flow to form an air curtain to isolate the atmosphere. Studies have shown that the sealing cover method is better than the air curtain method in preventing secondary oxidation of molten steel. However, the sealing cover method has a harsh working environment and is easily damaged due to contact with high-temperature ladles or middle pouring pipes. Vacuum extraction is often required before use, and high requirements are placed on sealing processes and materials. Therefore, it has not been used on a large scale in practice. In addition, in order to overcome the problem of obstructed observation line of sight, the protective device based on the principle of the sealing cover method often sets one or more visual observation windows on the sealing cover, which further increases the complexity of the equipment and increases the preparation cost. The air curtain method has a simple structure, is easy to use in production, and is widely used. 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 air inlet pipe), and its overall stability is poor.

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

[0005] The purpose of the present invention is to provide a downward spraying molten steel injection protection device with a spray cone annular air curtain, which solves the technical problems of the existing mold casting atmosphere protection device, such as poor isolation stability of atmosphere / molten steel, high sealing requirements and complex equipment structure.

[0006] To achieve the above purpose, the technical solution used in the present invention is:

[0007] The invention discloses a downward spraying type molten steel injection protection device for spraying a tapered annular air curtain, characterized in that it comprises an outer guide ring wall of a protective cover, an inner guide ring wall of a protective cover, an air intake device and an observation unit; the outer guide ring wall of the protective cover and the inner guide ring wall of the protective cover are tapered cylinder walls, and the tapers of the two are the same; the outer guide ring wall of the protective cover and the inner guide ring wall of the protective cover are fixedly mounted on the same central axis to form an annular gap; the annular gap is used to spray an annular air curtain, and the spraying direction of the annular air curtain points to the upper gate of the middle injection pipe; the air intake device is connected to the annular gap and is used to send inert gas to the annular gap; after the inert gas enters the annular gap, it sprays out an annular air curtain from the other end, and the spraying direction points to the upper gate of the middle injection pipe; the characteristic size of the air intake device is more than 40 times that of the annular gap, and the pressure and speed of the inert gas are significantly increased after entering the annular gap from the air intake device, so that the spraying speed is high, so it is easier to resist the impact of various high-temperature airflows during molten steel injection, and the stability of the air curtain is enhanced.

[0008] Furthermore, the taper range of the outer guide ring wall of the protective cover and the inner guide ring wall of the protective cover is 1-5°; the overall thickness (L1) of the annular gap is consistent, and the thickness range is 0.5-3mm; the taper of 1-5° ensures that the diameter of the annular air curtain gradually expands toward the center injection pipe to form a tapered annular air curtain; flow field simulation calculations show that since the tapered annular air curtain has the largest diameter above the center injection pipe, it has better stability in resisting high-temperature expanding airflow, and can avoid being sucked into the center injection pipe by the molten steel too quickly, causing excessive steel suction; 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 center 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 the extension direction is toward the injection direction of the air curtain; 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, and the short length range is 5-12mm; after flow field calculation, the 5-12mm inner guide ring wall surface can effectively prevent the air curtain from deflecting toward the inner side of the inner protective brick due to "jet attachment to the wall".

[0010] Furthermore, the outer guide ring wall of the protective cover is fixed by an upper supporting brick, a retractable supporting rod and a slot of the inner guide ring wall; the retractable supporting rod is a threaded screw and a nut, and the retractability is achieved by rotating the nut; the threaded screw penetrates the upper supporting brick, and the front end of the screw located on the outer wall side of the upper supporting brick is flush with the end of the outer wall surface of the inner guide ring wall, and the nut is located on the inner wall side of the upper supporting brick; the front end of the screw is flush with the end of the outer wall surface to avoid disturbing the flow field near the annular air curtain outlet; there are 6 to 12 retractable supporting rods, which are evenly distributed on the upper supporting brick; the diameter and number of the screw are preferentially assembled according to the weight of the outer guide ring wall of the protective cover to firmly 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 is the same as the outer diameter of the inner protective brick; the inner wall of the upper protective brick fits tightly with the outer wall of the inner protective brick, and the assembly is completed by tightening the parts; the top of the upper protective brick and the inner protective brick are connected to the bottom plate of the 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, and is used to transport inert gas into the air chamber; the inner surface of the air intake pipe is tangent to the inner wall of the air chamber; the central axis of the air intake pipe is always located on the air intake plane; the central axis of the air intake pipe forms an air intake angle with the central axis, ranging from -80-80°; according to flow field calculation, compared with other air intake methods, such as vertical air intake from the side of the outer wall of the air chamber, and vertical air intake from the upper surface or lower surface of the outer wall of the air chamber, tangential air intake can allow the inert gas to fill the air chamber as quickly as possible, greatly reducing the air intake volume; the tangential air intake method enables the injection gas curtain to have a tangential velocity component, which is significantly beneficial for the gas curtain itself to maintain its integrity during the injection of molten steel and isolate it from the atmosphere; the injection angle a1, air intake flow rate and air intake angle a2 of the atmosphere protection device of the present invention can be adjusted separately, so as to flexibly and accurately control the injection trajectory and injection 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 close to the annular gap; the inner top of the air chamber is connected to the annular gap air inlet, which is used for the air chamber to transport gas to the annular gap; according to flow field calculation, a single annular air chamber (13) with a smooth inner wall and no edges is combined with a tangential air intake method, and under the same air intake flow rate, the inert gas in the air chamber can generate maximum pressure on the annular gap air inlet, thereby promoting the injection of a high-speed, uniform-thickness air curtain.

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

[0015] The technical effects of the present invention include:

[0016] The present invention forms an annular gap structure, connects the gap to an annular air chamber that is several times the size of the gap, and simultaneously uses a method of rapid tangential air intake to the air chamber, so as to spray a high-speed, uniformly thick, and tightly surrounding tapered annular air curtain around the molten steel. The tapered annular air curtain formed is stable and strong when high-temperature molten steel is injected, effectively isolating the molten steel from contacting the atmosphere, and completely avoiding secondary oxidation of the molten steel. The injection protection device of the present invention is simple in structural design, processing, and installation, and has no special sealing requirements. It uses a pressure monitor and an oxygen concentration detector with tempered glass as an observation window, which can detect the argon flow rate and oxygen concentration in real time, and adjust the argon intake flow rate in time to maximize the protection effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1a It is a schematic diagram of the cross-sectional structure of the present invention;

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

[0019] Figure 2 It is a schematic diagram of the three-dimensional structure of the present invention;

[0020] Figure 3 It is a top view of FIG. 1 of the present invention;

[0021] Figure 4 For the present invention Figure 3 The right view of the , and only some units are shown;

[0022] Figure 5 It is a schematic cross-sectional structure diagram of the protective cover outer guide ring wall 1, the protective cover 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 markings in the figure are:

[0024] 1. Outer guide ring wall of protective cover; 2. Inner guide ring wall of protective cover; 3. Annular gap; 4. Annular gap air inlet; 5. Air curtain outlet; 6. Upper support brick; 7. Retractable support rod; 8. Upper protection brick; 9. Inner guide ring wall slot; 10. Inner protection 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 DESCRIPTION

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

[0026] Example 1

[0027] According to the oxygen concentration detection and statistics of the inert atmosphere generated by the early protection device at the molten steel pouring site. It was found that when the molten steel injection diameter is 45-50cm, the injection height is greater than 35cm, and the injection speed is greater than 52kg / s, the inert gas curtain is easily destroyed (the oxygen concentration rises rapidly within a few seconds). When the molten steel injection diameter is below 42cm, the injection height is 20cm-30cm, and the injection speed is below 44kg / s, the inert gas curtain is maintained for a longer time. This embodiment is applicable to the working conditions of molten steel injection diameter of 35cm, injection height of 25cm, and molten steel injection speed of 40kg / s. Under the said working conditions, the injection molten steel has a weak suction effect on the gas curtain, the exposed distance required to protect the sprayed annular gas curtain is short, and the air discharged after the injection molten steel enters the middle injection pipe has a low impact on the annular gas curtain.

[0028] like Figure 1a-Figure 3 As shown, a downward spraying type molten steel injection protection device for spraying a conical annular air curtain of the present invention comprises an outer guide ring wall 1 of a protective cover, an inner guide ring wall 2 of a protective cover and an air intake device 11. The outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover have the same taper, and the two are fixed with the same central axis to form an annular gap 3. The taper range of the outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover is 1 to 5°, and 1° is preferred in this embodiment. The preferred taper is suitable for the working condition of the low injection speed of this embodiment. The injection speed is small, and the entrainment effect on the air curtain is weak, so there is no need to increase the injection angle to resist the serious air intake of the molten steel caused by excessive entrainment. The air intake device 11 is used to supply air to the annular gap 3. The annular gap 3 is used to spray an annular air curtain in the direction of the lower middle injection pipe to enclose the injection molten steel and isolate it from the atmosphere. The thickness L1 of the annular gap is consistent, and the thickness range is 0.5-3mm, and 0.5mm is preferred in this embodiment. In this embodiment, the thickness L1 of the preferred annular gap 3 is sufficient to keep the integrity of the gas curtain when the molten steel is injected to discharge the air in the middle injection pipe, while reducing the intake air flow rate.

[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 length L2 in the range of 5-12mm, and 5mm is preferred in this embodiment. According to the flow field calculation, this section of the 5mm inner guide ring wall surface can effectively prevent the air curtain from deflecting toward the inner side of the inner protection brick due to the "jet wall attachment". The inner guide ring wall 2 of the protective cover is fixed by the upper support brick 6, the retractable support rod 7 and the inner guide ring wall groove 9. The retractable support rod 7 is a threaded screw and nut, and the extension is achieved by rotating the nut. Preferably, there are 8 retractable support rods 7, which are evenly distributed on the upper support brick 6. The inner guide ring wall groove 9 is formed by assembling the upper protection brick 8 and the inner protection brick 10. The inner wall of the upper protection brick 8 fits tightly with the outer wall of the inner protection brick 10, and the assembly is completed by tightening the parts.

[0030] The inner surface of the air intake passage 12 of this embodiment is tangent to the inner wall of the air chamber 13, and there is an air intake angle a2 ( Figure 3 ), a2 ranges from -80 to 80°, and 80° is preferred in this embodiment. Through flow field calculation, it is known that when the air intake angle increases from 0° to 10°, the injection speed of the air curtain ejected from the annular gap 3 gradually decreases. The preferred taper and air intake angle of this embodiment can ensure an annular air curtain with a lower injection speed. This embodiment also includes an observation unit 14, and the observation unit 14 includes 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 the smaller injection height, and is directly placed 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 the smaller injection speed. 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 under 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 suitable for the working condition of molten steel injection diameter of 50cm, injection height of 40cm, and molten steel injection speed of 60kg / s. Under the working condition, the injection molten steel has a strong entrainment effect on the air curtain, and the exposed distance required to protect the sprayed annular air curtain is long. In addition, the air discharged after the injection molten steel enters the middle injection pipe has a strong impact on the annular air curtain.

[0033] The basic content of this embodiment is the same as that of the embodiment 1, except that: the guide ring wall 2 in the protective cover forms a spray angle a1 with the central axis Z1, and the spray angle a1 ranges from 1 to 5° ( Figure 1a , Figure 1b ), and 3° is preferred in this embodiment. The preferred injection angle a1 is suitable for the working conditions of the present embodiment with large injection velocity and large injection diameter. As the injection angle a1 increases, the strong entrainment effect of the injected molten steel can be appropriately resisted. The outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover form an annular gap 3, and the annular gap thickness L1 is consistent, and 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 annular gap thickness L1, the stronger the ability to resist exhaust shock. 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, and the difference in length range is 5-12mm, and 5mm is preferred in this embodiment. According to the multiphase flow field calculation, the 5mm inner guide ring wall surface can effectively prevent the air curtain from deflecting to the inner side of the inner protective brick due to the "jet wall attachment". The inner surface of the air intake passage 12 of this embodiment is tangent to the inner wall of the air chamber 13, and there is an air intake angle a2 ( Figure 3), a2 ranges from -80 to 80°, and 0° is preferred in this embodiment. This preferred air inlet angle can ensure that the air chamber is quickly filled with inert gas, the inlet pressure of the annular gap 3 is high, and the annular air curtain injection speed is high enough, which is suitable for the working conditions of large annular gap thickness and high injection height.

[0034] Example 3

[0035] According to the oxygen concentration detection and statistics of the inert atmosphere generated by the early protection device at the molten steel pouring site. It was found that when the molten steel injection diameter is 45-50cm, the injection height is greater than 35cm, and the injection speed is greater than 52kg / s, the inert gas curtain is easily destroyed (the oxygen concentration rises rapidly within a few seconds). When the molten steel injection diameter is below 42cm, the injection height is 20cm-30cm, and the injection speed is below 44kg / s, the inert gas curtain is maintained for a longer time. This embodiment is applicable to the working conditions of molten steel injection diameter of 35cm, injection height of 25cm, and molten steel injection speed of 40kg / s. Under the said working conditions, the injection molten steel has a weak suction effect on the gas curtain, the exposed distance required to protect the sprayed annular gas curtain is short, and the air discharged after the injection molten steel enters the middle injection pipe has a low impact on the annular gas curtain.

[0036] like Figure 1a-Figure 3 As shown, a downward spraying type molten steel injection protection device for spraying a conical annular air curtain of the present invention comprises an outer guide ring wall 1 of a protective cover, an inner guide ring wall 2 of a protective cover and an air intake device 11. The outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover have the same taper, and the two are fixed with the same central axis to form an annular gap 3. The taper range of the outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover is 1 to 5°, and 2° is preferably used in this embodiment. The preferred taper is suitable for the working condition of the low injection speed of this embodiment. The injection speed is small, and the entrainment effect on the air curtain is weak, so there is no need to increase the injection angle to resist the serious air intake of the molten steel caused by excessive entrainment. The air intake device 11 is used to supply air to the annular gap 3. The annular gap 3 is used to spray an annular air curtain in the direction of the lower middle injection pipe to enclose the injection molten steel and isolate it from the atmosphere. The thickness L1 of the annular gap is consistent, and the thickness range is 0.5-3mm, and 0.5mm is preferably used in this embodiment. In this embodiment, the thickness L1 of the preferred annular gap 3 is sufficient to keep the integrity of the gas curtain when the molten steel is injected to discharge the air in the middle injection pipe, while reducing the intake air flow rate.

[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 length L2 in the range of 5-12mm, and 5mm is preferred in this embodiment. According to the flow field calculation, this section of the 5mm inner guide ring wall surface can effectively prevent the air curtain from deflecting toward the inner side of the inner protection brick due to the "jet wall attachment". The inner guide ring wall 2 of the protective cover is fixed by the upper support brick 6, the retractable support rod 7 and the inner guide ring wall groove 9. The retractable support rod 7 is a threaded screw and nut, and the extension is achieved by rotating the nut. Preferably, there are 8 retractable support rods 7, which are evenly distributed on the upper support brick 6. The inner guide ring wall groove 9 is formed by assembling the upper protection brick 8 and the inner protection brick 10. The inner wall of the upper protection brick 8 fits tightly with the outer wall of the inner protection brick 10, and the assembly is completed by tightening the parts.

[0038] The inner surface of the air intake passage 12 of this embodiment is tangent to the inner wall of the air chamber 13, and there is an air intake angle a2 ( Figure 3 ), a2 ranges from -80 to 80°, and 60° is preferred in this embodiment. Through flow field calculation, it is known that when the air intake angle increases from 0° to 10°, the injection speed of the air curtain ejected from the annular gap 3 gradually decreases. The preferred taper and air intake angle of this embodiment can ensure an annular air curtain with a lower injection speed. This embodiment also includes an observation unit 14, and the observation unit 14 includes 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 the smaller injection height, and is directly placed 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 the smaller injection speed. 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 under the oxygen concentration detector 17. The pressure monitor 16 and the oxygen concentration detector 17 use existing high temperature resistant products.

[0039] Example 4

[0040] This embodiment is suitable for the working condition of molten steel injection diameter of 50cm, injection height of 40cm, and molten steel injection speed of 60kg / s. Under the working condition, the injection molten steel has a strong entrainment effect on the air curtain, and the exposed distance required to protect the sprayed annular air curtain is long. In addition, the air discharged after the injection molten steel enters the middle injection pipe has a strong impact on the annular air curtain.

[0041] The basic content of this embodiment is the same as that of the embodiment 1, except that: the guide ring wall 2 in the protective cover forms a spray angle a1 with the central axis Z1, and the spray angle a1 ranges from 1 to 5° ( Figure 1a , Figure 1b), and 4° is preferred in this embodiment. The preferred injection angle a1 is suitable for the working conditions of the present embodiment with large injection velocity and large injection diameter. As the injection angle a1 increases, the strong entrainment effect of the injected molten steel can be appropriately resisted. The outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover form an annular gap 3, and the thickness L1 of the annular gap is consistent, and 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, the stronger the ability to resist exhaust shock. 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, and the difference in length range is 5-12mm, and 5mm is preferred in this embodiment. According to the multiphase flow field calculation, the 5mm inner guide ring wall surface of this section can effectively prevent the air curtain from deflecting to the inner side of the inner protective brick due to the "jet wall attachment". The inner surface of the air intake passage 12 of this embodiment is tangent to the inner wall of the air chamber 13, and there is an air intake angle a2 ( Figure 3 ), a2 ranges from -80 to 80°, and 0° is preferred in this embodiment. This preferred air inlet angle can ensure that the air chamber is quickly filled with inert gas, the inlet pressure of the annular gap 3 is high, and the annular air curtain injection speed is high enough, which is suitable for the working conditions of large annular gap thickness and high injection height.

[0042] Example 5

[0043] According to the oxygen concentration detection and statistics of the inert atmosphere generated by the early protection device at the molten steel pouring site. It was found that when the molten steel injection diameter is 45-50cm, the injection height is greater than 35cm, and the injection speed is greater than 52kg / s, the inert gas curtain is easily destroyed (the oxygen concentration rises rapidly within a few seconds). When the molten steel injection diameter is below 42cm, the injection height is 20cm-30cm, and the injection speed is below 44kg / s, the inert gas curtain is maintained for a longer time. This embodiment is applicable to the working conditions of molten steel injection diameter of 35cm, injection height of 25cm, and molten steel injection speed of 40kg / s. Under the said working conditions, the injection molten steel has a weak suction effect on the gas curtain, the exposed distance required to protect the sprayed annular gas curtain is short, and the air discharged after the injection molten steel enters the middle injection pipe has a low impact on the annular gas curtain.

[0044] like Figure 1a-Figure 3As shown, a downward spraying type molten steel injection protection device for spraying a conical annular air curtain of the present invention comprises an outer guide ring wall 1 of a protective cover, an inner guide ring wall 2 of a protective cover and an air intake device 11. The outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover have the same taper, and the two are fixed with the same central axis to form an annular gap 3. The taper range of the outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover is 1 to 5°, and 5° is preferably used in this embodiment. The preferred taper is suitable for the working condition of the low injection speed of this embodiment. The injection speed is small, and the entrainment effect on the air curtain is weak, so there is no need to increase the injection angle to resist the serious air intake of the molten steel caused by excessive entrainment. The air intake device 11 is used to supply air to the annular gap 3. The annular gap 3 is used to spray an annular air curtain in the direction of the lower middle injection pipe to enclose the injection molten steel and isolate it from the atmosphere. The thickness L1 of the annular gap is consistent, and the thickness range is 0.5-3mm, and 0.5mm is preferably used in this embodiment. In this embodiment, the thickness L1 of the preferred annular gap 3 is sufficient to keep the integrity of the gas curtain when the molten steel is injected to discharge the air in the middle injection pipe, while reducing the intake air flow rate.

[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 length L2 in the range of 5-12mm, and 5mm is preferred in this embodiment. According to the flow field calculation, this section of the 5mm inner guide ring wall surface can effectively prevent the air curtain from deflecting toward the inner side of the inner protection brick due to the "jet wall attachment". The inner guide ring wall 2 of the protective cover is fixed by the upper support brick 6, the retractable support rod 7 and the inner guide ring wall groove 9. The retractable support rod 7 is a threaded screw and nut, and the extension is achieved by rotating the nut. Preferably, there are 8 retractable support rods 7, which are evenly distributed on the upper support brick 6. The inner guide ring wall groove 9 is formed by assembling the upper protection brick 8 and the inner protection brick 10. The inner wall of the upper protection brick 8 fits tightly with the outer wall of the inner protection brick 10, and the assembly is completed by tightening the parts.

[0046] The inner surface of the air intake passage 12 of this embodiment is tangent to the inner wall of the air chamber 13, and there is an air intake angle a2 ( Figure 3), a2 ranges from -80 to 80°, and 50° is preferred in this embodiment. Through flow field calculation, it is known that when the air intake angle increases from 0° to 10°, the injection speed of the air curtain ejected from the annular gap 3 gradually decreases. The preferred taper and air intake angle of this embodiment can ensure an annular air curtain with a lower injection speed. This embodiment also includes an observation unit 14, and the observation unit 14 includes 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 the smaller injection height, and is directly placed 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 the smaller injection speed. 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 under 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 suitable for the working condition of molten steel injection diameter of 50cm, injection height of 40cm, and molten steel injection speed of 60kg / s. Under the working condition, the injection molten steel has a strong entrainment effect on the air curtain, and the exposed distance required to protect the sprayed annular air curtain is long. In addition, the air discharged after the injection molten steel enters the middle injection pipe has a strong impact on the annular air curtain.

[0049] The basic content of this embodiment is the same as that of the embodiment 1, except that: the guide ring wall 2 in the protective cover forms a spray angle a1 with the central axis Z1, and the spray angle a1 ranges from 1 to 5° ( Figure 1a , Figure 1b ), and 1° is preferred in this embodiment. The preferred injection angle a1 is suitable for the working conditions of the present embodiment with large injection velocity and large injection diameter. As the injection angle a1 increases, the strong entrainment effect of the injected molten steel can be appropriately resisted. The outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover form an annular gap 3, and the annular gap thickness L1 is consistent, and 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 annular gap thickness L1, the stronger the ability to resist exhaust shock. 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, and the difference in length range is 5-12mm, and 5mm is preferred in this embodiment. According to the multiphase flow field calculation, the 5mm inner guide ring wall surface can effectively prevent the air curtain from deflecting to the inner side of the inner protective brick due to the "jet wall attachment". The inner surface of the air intake passage 12 of this embodiment is tangent to the inner wall of the air chamber 13, and there is an air intake angle a2 ( Figure 3), a2 ranges from -80 to 80°, and -10° is preferred in this embodiment. This preferred air inlet angle can ensure that the air chamber is quickly filled with inert gas, the inlet pressure of the annular gap 3 is high, and the annular air curtain injection speed is high enough, which is suitable for the working conditions of large annular gap thickness and high injection height.

[0050] Example 7

[0051] According to the oxygen concentration detection and statistics of the inert atmosphere generated by the early protection device at the molten steel pouring site. It was found that when the molten steel injection diameter is 45-50cm, the injection height is greater than 35cm, and the injection speed is greater than 52kg / s, the inert gas curtain is easily destroyed (the oxygen concentration rises rapidly within a few seconds). When the molten steel injection diameter is below 42cm, the injection height is 20cm-30cm, and the injection speed is below 44kg / s, the inert gas curtain is maintained for a longer time. This embodiment is applicable to the working conditions of molten steel injection diameter of 35cm, injection height of 25cm, and molten steel injection speed of 40kg / s. Under the said working conditions, the injection molten steel has a weak suction effect on the gas curtain, the exposed distance required to protect the sprayed annular gas curtain is short, and the air discharged after the injection molten steel enters the middle injection pipe has a low impact on the annular gas curtain.

[0052] like Figure 1a-Figure 3 As shown, a downward spraying type molten steel injection protection device for spraying a conical annular air curtain of the present invention comprises an outer guide ring wall 1 of a protective cover, an inner guide ring wall 2 of a protective cover and an air intake device 11. The outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover have the same taper, and the two are fixed with the same central axis to form an annular gap 3. The taper range of the outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover is 1 to 5°, and 5° is preferably used in this embodiment. The preferred taper is suitable for the working condition of the low injection speed of this embodiment. The injection speed is small, and the entrainment effect on the air curtain is weak, so there is no need to increase the injection angle to resist the serious air intake of the molten steel caused by excessive entrainment. The air intake device 11 is used to supply air to the annular gap 3. The annular gap 3 is used to spray an annular air curtain in the direction of the lower middle injection pipe to enclose the injection molten steel and isolate it from the atmosphere. The thickness L1 of the annular gap is consistent, and the thickness range is 0.5-3mm, and 0.5mm is preferably used in this embodiment. In this embodiment, the thickness L1 of the preferred annular gap 3 is sufficient to keep the integrity of the gas curtain when the molten steel is injected to discharge the air in the middle injection pipe, while reducing the intake air flow rate.

[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 length L2 in the range of 5-12mm, and 5mm is preferred in this embodiment. According to the flow field calculation, this section of the 5mm inner guide ring wall surface can effectively prevent the air curtain from deflecting toward the inner side of the inner protection brick due to the "jet wall attachment". The inner guide ring wall 2 of the protective cover is fixed by the upper support brick 6, the retractable support rod 7 and the inner guide ring wall groove 9. The retractable support rod 7 is a threaded screw and nut, and the extension is achieved by rotating the nut. Preferably, there are 8 retractable support rods 7, which are evenly distributed on the upper support brick 6. The inner guide ring wall groove 9 is formed by assembling the upper protection brick 8 and the inner protection brick 10. The inner wall of the upper protection brick 8 fits tightly with the outer wall of the inner protection brick 10, and the assembly is completed by tightening the parts.

[0054] The inner surface of the air intake passage 12 of this embodiment is tangent to the inner wall of the air chamber 13, and there is an air intake angle a2 ( Figure 3 ), a2 ranges from -80 to 80°, and -70° is preferred in this embodiment. Through flow field calculation, it is known that when the air intake angle increases from 0° to 10°, the injection speed of the air curtain ejected from the annular gap 3 gradually decreases. The preferred taper and air intake angle of this embodiment can ensure an annular air curtain with a lower injection speed. This embodiment also includes an observation unit 14, and the observation unit 14 includes 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 the smaller injection height, and is directly placed 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 the smaller injection speed. 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 under 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 suitable for the working condition of molten steel injection diameter of 50cm, injection height of 40cm, and molten steel injection speed of 60kg / s. Under the working condition, the injection molten steel has a strong entrainment effect on the air curtain, and the exposed distance required to protect the sprayed annular air curtain is long. In addition, the air discharged after the injection molten steel enters the middle injection pipe has a strong impact on the annular air curtain.

[0057] The basic content of this embodiment is the same as that of the embodiment 1, except that: the guide ring wall 2 in the protective cover forms a spray angle a1 with the central axis Z1, and the spray angle a1 ranges from 1 to 5° ( Figure 1a , Figure 1b), and 3° is preferred in this embodiment. The preferred injection angle a1 is suitable for the working conditions of the present embodiment with large injection velocity and large injection diameter. As the injection angle a1 increases, the strong entrainment effect of the injected molten steel can be appropriately resisted. The outer guide ring wall 1 of the protective cover and the inner guide ring wall 2 of the protective cover form an annular gap 3, and the annular gap thickness L1 is consistent, and 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 annular gap thickness L1, the stronger the ability to resist exhaust shock. 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, and the difference in length range is 5-12mm, and 5mm is preferred in this embodiment. According to the multiphase flow field calculation, the 5mm inner guide ring wall surface can effectively prevent the air curtain from deflecting to the inner side of the inner protective brick due to the "jet wall attachment". The inner surface of the air intake passage 12 of this embodiment is tangent to the inner wall of the air chamber 13, and there is an air intake angle a2 ( Figure 3 ), a2 ranges from -80 to 80°, and -80° is preferred in this embodiment. This preferred air inlet angle can ensure that the air chamber is quickly filled with inert gas, the inlet pressure of the annular gap 3 is high, and the annular air curtain injection speed is high enough, which is suitable for the working conditions of large annular gap thickness and high injection height.

[0058] The steps for pouring protection in place are:

[0059] 1. Before the ladle is filled with molten steel, the inner protection brick 10 and the upper protection brick 8 are screwed and installed around the ladle outlet. Then the upper support brick 6 with the telescopic rod 7 is screwed and installed at the lower end of the upper protection brick 8. After installing the upper support brick 6, adjust the end length of the telescopic rod 7 to the preset value.

[0060] 2. Before the steel package contains molten steel, 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 air chamber 13 and the outer guide ring wall 1 of the protective cover on the lower end of the upper protective brick 8 by tightening. The inner guide ring wall 2 of the protective cover and the outer guide ring wall 1 of the protective cover have the same rotation axis. After the air 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 air chamber 13 with refractory fiber material, and fix the air inlet angle a2.

[0061] 3. After the ladle car arrives at the pouring position, the ladle car is operated to move the ladle downward, and then an observation cover is placed on the upper end surface of the middle pouring pipe. After the placement is completed, argon gas is introduced from the air inlet channel 12 to form an annular air curtain. Then the molten steel begins to be poured, and the data of the oxygen detector 16 and the pressure monitor 17 are observed at the same time, so as to adjust the air inlet flow at any time.

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

[0063] 5. After completing the pouring at all pouring stations, turn off the argon switch. After the ladle car reaches the disassembly position, remove the injection flow protection device.

[0064] The terms used in the present invention are illustrative and exemplary, rather than restrictive. Since the present invention can be implemented in various 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 aforementioned details, but should be widely interpreted within the spirit and scope defined by the attached claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the attached claims.

Claims

1. A downward spraying type molten steel injection protection device with a conical annular air curtain, characterized in that: include: A protective cover outer guide ring wall (1), a protective cover inner guide ring wall (2), an air intake device (11) and an observation unit (14); the protective cover outer guide ring wall (1) and the protective cover inner guide ring wall (2) are tapered cylindrical walls, and the tapers of the two are the same; the protective cover outer guide ring wall (1) and the protective cover inner guide ring wall (2) are fixedly mounted on the same central axis to form an annular gap (3); the annular gap (3) is used to spray an annular air curtain, and the spraying direction of the annular air curtain points to the upper gate of the center injection pipe; the air intake device (11) is connected to supply inert gas to the annular gap (3).

2. The downward spraying type molten steel injection protection device with a spray cone annular air curtain according to claim 1 is characterized in that: The taper range of the outer guide ring wall (1) of the protective cover and the inner guide ring wall (2) of the protective cover is 1-5 degrees, and the overall thickness (L1) of the annular gap is consistent, and the thickness range is 0.5-3mm.

3. The downward spraying type molten steel injection protection device with a spray cone annular air curtain according to claim 1 is characterized in that: The outer guide ring wall (1) of the protective cover is connected to the air inlet device (11), and the extension direction is toward the air curtain spraying direction; The end of the guide ring wall (1) outside the protective cover is longer than the end of the guide ring wall (2) inside the protective cover, and the end difference distance (L2) ranges from 5 to 12 mm.

4. The downward spraying type molten steel injection protection device with a spray cone annular air curtain according to claim 1 is characterized in that: The inner flow-guiding ring wall (2) of the protective cover is fixed by an upper supporting brick (6), a telescopic supporting rod (7) and an inner flow-guiding ring wall clamping groove (9).

5. The downward spraying type molten steel injection protection device for spraying a conical annular air curtain according to claim 4 is characterized in that: The telescopic support rod (7) is a threaded screw and a nut, and the extension and retraction are achieved by rotating the nut; the threaded screw penetrates the upper support brick (6), 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 6 to 12 telescopic support rods (7) in total, which are evenly distributed on the upper support brick (6).

6. The downward spraying type molten steel injection protection device for spraying a conical annular air curtain according to claim 4 is characterized in that: The thickness (L3) of the inner guide ring wall groove (9) is twice the thickness (L1) of the annular gap; the inner guide ring wall groove (9) is formed by assembling an upper protection brick (8) and an inner protection brick (10); the inner diameter of the upper protection brick (8) is the same as the outer diameter of the inner protection brick (10); the inner wall of the upper protection brick (8) and the outer wall of the inner protection brick (10) are tightly fitted to complete the assembly; the tops of the upper protection brick (8) and the inner protection brick (10) are connected to the bottom plate of the ladle.

7. The downward spraying type molten steel injection protection device with a spray cone annular air curtain according to claim 1 is characterized in that: The air intake device (11) comprises an air intake passage (12) and an air chamber (13).

8. The downward spraying type molten steel injection protection device with a spray cone annular air curtain according to claim 7 is characterized in that: The air intake channel (12) is a hollow cylindrical tube connected to the air chamber (13) and used for conveying 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 is always 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) in the range of -80-80°.

9. The downward spraying type molten steel injection protection device with a spray cone annular air curtain according to claim 7 is 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 close to the annular gap; the inner top of the air chamber (13) is connected to the annular gap air inlet (4) for the air chamber (13) to transport gas to the annular gap.

10. The downward spraying type molten steel injection protection device with a conical annular air curtain according to claim 1 is characterized in that: The device also comprises an observation unit (14), the observation unit (14) comprising an observation cover (15), a pressure monitor (16) and an oxygen concentration detector (17), the observation cover (15) being located 5-10 cm below the lower edge of the upper support brick (6), the inner diameter of the observation cover (15) being larger than the outer diameter of the upper protective brick by 0-30 cm; the material of the observation cover (15) is high temperature resistant tempered glass, the pressure monitor (16) and the oxygen concentration detector (17) are placed and fixed by punching a hole on the observation cover, the height of the hole does not exceed half the height of the protective cover, and the pressure detector (16) is located below the oxygen concentration detector (17).

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