A continuous casting long nozzle argon sealing structure, argon blowing control system and control process

Abstract

A continuous casting long nozzle argon sealing structure, argon blowing control system and control process belong to the technical field of steelmaking, the continuous casting long nozzle argon sealing structure, including long nozzle body and the bowl part outer periphery of its covering shell, the shell is provided with argon inlet, the bowl part outer periphery is provided with annular groove, the volume of the annular groove gradually increases from the argon inlet to its opposite side, the beneficial effects of the present application are that the argon sealing structure designed in the application is simple, the manufacturing cost is low, the argon is uniformly and effectively distributed in the long nozzle circumferential direction, the argon blowing control system and process involved automatically adjust the argon flow of corresponding gear according to the net weight of molten steel in the ladle, the argon blowing effect of molten steel casting process is monitored in real time, the failure rate is reduced, and the quality of molten steel is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of steelmaking, and in particular to an argon sealing structure for a continuous casting shroud, an argon blowing control system and a control process. Background Art

[0002] As the service areas of metallurgical products continue to expand and the service conditions become more demanding, the metallurgical quality requirements for the products are also becoming increasingly higher. In recent years, refining technology and processes have continued to advance. Generally, after the secondary refining process, the purity of the molten steel is relatively high, and the inclusion and gas content in the steel can be controlled at very low levels. This places higher demands on the protection of casting during the continuous casting process. Secondary oxidation during the continuous casting process is one of the important factors affecting the purity of high-quality steel and even the quality of metallurgical products. Generally, high-quality steel contains a certain amount of aluminum. During the continuous casting process, the aluminum in the steel easily reacts with oxygen in the air to form clustered Al2O3 inclusions, which directly affect the purity of the molten steel and the quality of the ingot. In severe cases, it may even cause nozzle nodules and interrupted casting, affecting smooth production.

[0003] During the continuous casting process, due to the structural characteristics of the shroud and ladle outlet, a gap exists at the lower end of the shroud bowl. During the pouring process, the high-speed steel flow creates a negative pressure in this area. According to Bernoulli's principle in fluid mechanics, the greater the flow rate, the greater the negative pressure. Consequently, during the pouring process, the negative pressure created by the rapid steel flow can easily draw air in through the contact area between the shroud and the ladle outlet. Metallurgists both domestically and internationally have conducted extensive research on this issue, proposing several control techniques. Because the shroud and ladle outlet are in hard contact at high temperatures, a complete seal cannot be achieved. Therefore, current research focuses on argon sealing, which creates an argon atmosphere between the shroud and the ladle outlet. The gas drawn in under the negative pressure is argon, thus preventing air from coming into contact with the molten steel and improving the continuous casting protection.

[0004] In the argon seal design, the slit-type argon blowing method in the long nozzle bowl area is currently the most widely used, such as Figure 1 As shown, this method has certain problems during use. Due to the characteristics of the long nozzle manufacturing process, the argon gas chamber formed by the outer wall of the shell and the bowl of the long nozzle is relatively small, and the gap between them is only 1 to 2 mm. In addition, there is a certain roughness on the surface of the outer wall of the wrist of the long nozzle. The argon flow entering through the argon inlet will choose a path with less air resistance in the narrow and uneven space, forming a "short-circuit flow". The argon gas tends to flow out quickly from the argon outlet area closer to the argon inlet, and it is difficult to flow into the opposite side through the narrow channel of the argon gas chamber. It is impossible to achieve uniform distribution of argon gas in the argon outlet area. Most of the argon gas will flow out from the area closer to the argon inlet, that is, about 1 / 4 of the circumference of the argon outlet (such as Figure 2The argon gas outlet other circumferential 3 / 4 region is almost no argon gas outflow. In the area without argon gas outflow, air will be sucked in due to negative pressure during casting, which seriously affects the argon sealing protection casting effect, leading to secondary oxidation of molten steel. In the prior art, the patent with publication number CN216966269U discloses an argon sealing long nozzle for continuous casting tundish, which only considers the problem of flow deviation and formation of turbulent flow region in the argon blowing area, and does not consider the problem that most argon gas easily flows out from the local outlet area, so it is difficult to achieve the effect of uniform argon gas outflow in the circumferential direction, and the problem of uniform distribution of argon gas cannot be completely and effectively solved.

[0005] In addition, the existing long nozzle argon blowing adopts manual valve operation, which cannot accurately control the argon flow size, and when abnormal conditions such as gas leakage and gas interruption occur, which affect the argon blowing effect, online real-time alarm and deviation correction cannot be realized, thereby seriously affecting the stability of the long nozzle argon sealing protection casting effect.

[0006] Based on the above problems, how to realize the uniform distribution of argon gas in the nozzle bowl argon gas chamber during long nozzle argon blowing, maintain the long nozzle bowl argon outlet area in the argon sealing state during casting, effectively prevent secondary oxidation of molten steel due to contact with air, and at the same time, how to realize convenient operation of the control system and online real-time monitoring of the argon blowing effect and accurate control of the argon blowing flow, to ensure the stability and effectiveness of the long nozzle argon sealing effect, are the problems to be solved in the long nozzle argon sealing protection casting of high-quality steel. SUMMARY

[0007] To solve the above technical problems, the present application provides a continuous casting long nozzle argon sealing structure, which can realize the circumferential uniform distribution of argon gas, and at the same time, a set of argon blowing control system suitable for the device is established, which can accurately control the argon blowing flow and online real-time monitor the argon blowing effect, facilitate timely warning and deviation correction of abnormal conditions, and intelligently operate different argon blowing modes according to the long nozzle condition and casting period, reduce manual operation and argon waste.

[0008] To achieve the above purpose, the technical scheme adopted by the present application to solve its technical problems is: the continuous casting long nozzle argon sealing structure comprises a long nozzle body and an outer shell wrapped around the bowl part of the long nozzle body, an argon gas inlet is arranged on the outer shell, an annular groove is arranged on the outer periphery of the bowl part, and the volume of the annular groove gradually increases from the argon gas inlet to the opposite side.

[0009] The outer shell and the long nozzle body form a slit space therebetween, and the slit space and the annular groove form an argon gas chamber.

[0010] The depth and width of the annular groove gradually increase from the argon gas inlet to the opposite side.

[0011] The depth of the annular groove is 3-8mm, and the width of the annular groove is 3-10mm.

[0012] The long nozzle body is made of aluminum magnesium carbonaceous ingredients, and each raw material ingredient and its weight percentage respectively comprises: 35-45% of fused alumina, 15-25% of fused magnesia, 15-25% of flaky graphite, 10-20% of active alumina, 5-10% of fused spinel and 2-4% of pure calcium aluminate cement.

[0013] An argon blowing control system of a continuous casting long nozzle argon sealing structure, comprising an argon pipeline system and an electrical control system, the argon pipeline system comprises an argon gas source and a normal branch and a standby branch connected thereto, the electrical control system comprises a PLC controller, an upper computer, a continuous casting automation system and a molten steel weighing system;

[0014] The PLC controller communicates with the upper computer through an industrial Ethernet, accepts the upper computer command and transmits the pressure and flow signals in the argon pipeline system to the upper computer;

[0015] The molten steel weighing system collects and sends the weight of the molten steel in the ladle to the continuous casting automation system, the continuous casting automation system communicates with the upper computer through an industrial Ethernet, the PLC controller accepts the upper computer command and adjusts the argon flow in the normal branch or controls the opening of the standby branch.

[0016] The gas inlet ends of the normal branch and the standby branch are connected with the argon gas source through a gas source inlet pipeline, a first manual ball valve and a pressure gauge are connected in the gas source inlet pipeline; the gas outlet ends of the normal branch and the standby branch are connected with the argon inlet through a gas source outlet pipeline, and a pressure transmitter is connected in the gas source outlet pipeline.

[0017] The normal branch comprises a first branch pipeline and a second manual ball valve, a first solenoid valve, a pressure reducing valve, a flow regulating valve and a mass flowmeter connected in sequence along the argon flow direction on the first branch pipeline, the pressure gauge, the pressure transmitter and the mass flowmeter are connected with the input end of the PLC controller, the output end of the PLC controller is connected with the flow regulating valve and the pressure reducing valve, and the output end of the PLC controller is connected with the first solenoid valve to control the conduction and the closing of the first branch pipeline.

[0018] The standby branch comprises a second branch pipeline and a third manual ball valve, a second solenoid valve and a manual regulating valve connected in sequence along the argon flow direction on the second branch pipeline, and the second solenoid valve receives the control signal of the PLC controller to control the conduction and the closing of the second branch pipeline.

[0019] An argon blowing control process of a continuous casting long nozzle argon sealing structure, comprising the following steps:

[0020] 1) In the early stage of molten steel pouring, open the argon gas source, blow argon into the argon inlet, the pressure of argon is controlled at 0.5-1.0 MPa, the argon flow is 150-250 NL / min, and the blowing is continued for 5-10 min;

[0021] 2) In the middle stage of molten steel pouring, the pressure of argon is kept at 0.5-1.0 MPa, the argon flow is adjusted to 50-150 NL / min, and the blowing is continued for 30-40 min;

[0022] 3) In the late stage of molten steel pouring, the pressure of argon is kept at 0.5-1.0 MPa, the argon flow is adjusted to 100-200 NL / min, and the blowing is continued for 1-5 min to promote the floating of steel slag;

[0023] 4) When the ladle stops pouring and the long nozzle is washed, the pressure of argon is kept at 0.5-1.0 MPa, the argon flow is adjusted to 50-100 NL / min, and the blowing is continued for 1-5 min;

[0024] 5) When the long nozzle washing is finished or the long nozzle is replaced, the argon gas source is closed and the argon blowing is stopped.

[0025] The beneficial effects of the present application are:

[0026] 1) On the basis of the existing argon sealing structure, according to the principle of fluid mechanics, an annular groove is designed in the outer peripheral area of the long nozzle bowl, the volume of the annular groove gradually increases from the argon inlet to the opposite side, by gradually expanding the volume of the argon chamber, reducing the air resistance, guiding the argon to uniformly distribute around the nozzle, and designing a suitable argon blowing control system and method, on the one hand, the problem of uneven distribution of argon around the argon outlet area is solved, on the other hand, the online real-time monitoring of argon sealing effect and the precise control of argon blowing flow are effectively realized, the long nozzle protection pouring effect is significantly improved, the molten steel quality is improved, and the manual operation and argon waste are reduced.

[0027] 2) The present application can accurately control the argon blowing flow of continuous casting long nozzle online, easily explore the control standard and operation monitoring, improve the stability of industrial process control and product quality; the instrument can be numerically controlled, the argon consumption and argon sealing time can be accurately inquired, and then through system calculation and analysis, an optimized gas supply curve is generated to optimize the cost reduction; the collected data can be analyzed, stored and backed up, providing reliable data for further research on continuous casting long nozzle argon blowing optimization and automatic control.

[0028] In summary, the argon seal for the continuous casting shroud involved in the present invention has a simple structure and low manufacturing cost, and enables the argon to be evenly and effectively distributed around the shroud. The argon blowing control system and process involved automatically adjust the argon flow rate of the corresponding gear according to the net weight of the molten steel in the ladle, and monitor the argon blowing effect of the molten steel casting process in real time, thereby reducing the failure rate, ensuring that the molten steel shroud is always in an argon-sealed state during the casting process, effectively preventing the molten steel from contacting with the air and causing secondary oxidation, and effectively improving the quality of the molten steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following is a brief description of the contents and symbols in the drawings of the present invention:

[0030] Figure 1 This is a full cross-sectional view of the long shroud argon seal structure in the prior art;

[0031] Figure 2 This is a top view of the long shroud argon seal structure in the prior art;

[0032] Figure 3 This is a full cross-sectional view of the argon seal structure of the continuous casting shroud of the present invention;

[0033] Figure 4 Schematic diagram of the external appearance of the annular groove in the argon seal structure of the continuous casting long nozzle of the present invention;

[0034] Figure 5 This is a control principle diagram of the argon blowing control system of the present invention;

[0035] Figure 6 It is a structural schematic diagram of the argon gas pipeline system of the present invention;

[0036] The marks in the above figures are: 1. Long nozzle body, 1-1. Bowl, 2. Outer shell, 3. Argon inlet, 4. Annular groove, 5. Argon chamber, 6. Gas inlet pipe, 7. First manual ball valve, 8. Pressure gauge, 9. Gas outlet pipe, 10. Pressure transmitter, 11. First branch pipe, 12. Second manual ball valve, 13. First solenoid valve, 14. Pressure reducing valve, 15. Flow regulating valve, 16. Mass flow meter, 17. Second branch pipe, 18. Third manual ball valve, 19. Second solenoid valve, 20. Manual regulating valve. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0038] In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0039] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0040] In the prior art, Figure 1 and Figure 2 As shown, the slit-type argon blowing method used in the shroud bowl 1-1 area is currently the most widely used. However, this method has certain problems during use. Due to the characteristics of the shroud manufacturing process, the argon chamber 5 formed between the shell and the outer wall of the shroud bowl 1-1 is relatively small, with a gap of only 1 to 2 mm. In addition, the outer wall surface of the shroud wrist has a certain degree of roughness. The argon flow entering through the argon inlet will choose a path with less air resistance in the narrow and uneven space, forming a "short-circuit flow". The argon gas tends to flow quickly from the argon outlet area closer to the argon inlet, and it is difficult to flow through the slit channel of the argon chamber 5 to the opposite side. Most of the argon gas will flow out from the area closer to the argon inlet, that is, the area around the argon outlet circumference of approximately 1 / 4 of the argon outlet, while almost no argon will flow out from the other 3 / 4 of the argon outlet circumference, making it impossible to achieve uniform distribution of argon gas in the argon outlet area. In the area without argon flow, air will be inhaled due to the negative pressure during casting, seriously affecting the argon seal protection casting effect and causing secondary oxidation of the molten steel.

[0041] Based on the above technical problems, the present invention provides a continuous casting long nozzle argon seal structure, such as Figure 3 and Figure 4 As shown, the argon sealing structure includes a long nozzle body 1 and a shell 2 covering the outer periphery of its bowl portion 1-1, an argon inlet 3 is provided on the shell 2, and an annular groove 4 is provided on the outer periphery of the bowl portion 1-1. The volume of the annular groove 4 gradually increases from the argon inlet 3 to the opposite side thereof. By gradually expanding the cross-sectional area of ​​the annular groove 4, the gas resistance is reduced, and the argon is guided to be evenly distributed circumferentially around the long nozzle body 1.

[0042] Specifically, the shell 2 and the long nozzle body 1 form a slit space, which forms an argon gas chamber 5 with the annular groove 4, and the argon gas chamber 5 is communicated with the argon inlet 3. The inner wall of the annular groove 4 is smooth, and the cross-sectional shape can be rectangular, trapezoidal or other shapes. The depth and width of the annular groove 4 gradually increase from the argon inlet 3 to the opposite side. The depth of the annular groove 4 is 3-8mm, and the width of the annular groove 4 is 3-10mm. The argon enters the argon gas chamber 5 from the argon inlet 3. Since the volume of the annular groove 4 gradually increases from the argon inlet 3 to the opposite side, the gas resistance gradually decreases in the direction away from the argon inlet 3, so the argon is guided in the direction away from the argon inlet 3, which can make the argon uniformly distributed around the long nozzle body 1.

[0043] Specifically, the long nozzle body 1 is made of aluminum-magnesium-carbon components, and each raw material component and its weight percentage includes: 35-45% of fused alumina, 15-25% of fused magnesia, 15-25% of flaky graphite, 10-20% of active alumina, 5-10% of fused spinel, and 2-4% of pure calcium aluminate cement. The component design is beneficial to improve the thermal shock fracture resistance of the long nozzle to meet the stable and effective operation of the long nozzle at high temperature for a long time under the condition of the groove 4. The above-mentioned annular groove 4 is designed before the long nozzle green body is made of long nozzle castable, and the filler is arranged in the formed area of the annular groove 4, and then the whole is sintered at high temperature after pouring. The filler is formed into the required annular groove 4 after high-temperature ablation. The long nozzle body 1 produced by the above-mentioned process has high structural strength, good thermal shock fracture resistance, simple production process, long service life and other advantages.

[0044] As shown in Figure 5 and Figure 6 , an argon blowing control system of a continuous casting long nozzle argon sealing structure includes an argon pipeline system and an electrical control system. The argon pipeline system includes an argon gas source and normal and standby branches connected thereto. The electrical control system includes a PLC controller, an upper computer, a continuous casting automation system and a molten steel weighing system.

[0045] The PLC controller communicates with the upper computer through industrial Ethernet, accepts the command of the upper computer, and transmits the pressure and flow signals in the argon pipeline system to the upper computer.

[0046] The molten steel weighing system collects and transmits the weight of the molten steel in the tundish to the continuous casting automation system, which communicates with the host computer via Industrial Ethernet. The host computer, through a command converter, converts preset logic signals into gear position signals and transmits them to the PLC controller. Based on the gear position signals, the PLC controller controls the opening of the flow controller to adjust the argon flow in the normal branch to match the flow rate changes during the subsequent casting stages. Alternatively, if the normal branch fails, it closes the normal branch and opens the backup branch. This adaptable system makes operation safer and more reliable, while preserving time for repairs in the event of a normal branch failure without affecting the casting process.

[0047] Specifically, the air inlet ends of the normal branch and the backup branch are connected to the argon gas source via an air inlet pipe 6. A first manual ball valve 7 and a pressure gauge 8 are connected to the air inlet pipe 6. The argon gas input air path can be opened and closed by operating the first manual ball valve 7. The pressure gauge 8 can detect the pressure of the argon gas in the air inlet pipe 6. The air outlet ends of the normal branch and the backup branch are connected to the argon gas inlet 3 via an air outlet pipe 9. A pressure transmitter 10 is connected to the air outlet pipe 9 to detect the pressure of the argon gas in the air outlet pipe 9 and input the pressure signal into the PLC controller for processing. The PLC controller automatically adjusts the valve opening in the normal branch to control the argon gas flow rate.

[0048] Specifically, the normal branch includes a first branch pipeline 11 and a second manual ball valve 12, a first solenoid valve 13, a pressure reducing valve 14, a flow regulating valve 15 and a mass flow meter 16 connected in series along the flow direction of argon gas. The second manual ball valve 12 is used to manually control the on-off of the first branch pipeline 11, and the first solenoid valve 13 is used to automatically control the on-off of the first branch pipeline 11, which plays a double-layer protection role. The pressure gauge 8, the pressure transmitter 10 and the mass flow meter 16 are connected to the input end of the PLC controller to detect the pressure signal of the gas source inlet pipeline 6, the pressure signal of the gas source outlet pipeline 9 and the first branch pipeline. The flow signal of pipeline 11 is transmitted to the PLC controller for processing. The output end of the PLC controller is connected to the flow regulating valve 15 and the pressure reducing valve 14. By controlling the flow regulating valve 15 and the pressure reducing valve 14, the argon flow in the first branch pipeline 11 is accurately adjusted. The output end of the PLC controller is also connected to the first solenoid valve 13 to control the conduction and closing of the first branch pipeline 11. According to the flow signal of the first branch pipeline 11, it is judged whether the first branch pipeline 11 has a fault. When a fault occurs, the normal branch is cut off by controlling the first solenoid valve 13 to close, and the backup branch is opened at the same time to achieve smooth switching between the normal branch and the backup branch. In addition, when the normal branch fails, the output end of the PLC controller can be connected to the alarm unit to control the alarm unit to alarm and remind the staff to take timely measures, making the operation safer and more reliable.

[0049] Specifically, the backup branch includes a second branch pipe 17 and a third manual ball valve 18, a second solenoid valve 19 and a manual regulating valve 20 connected in series along the flow direction of argon gas. The third manual ball valve 18 is used to manually adjust the on and off of the second branch pipe 17, and the second solenoid valve 19 is used to automatically control the on and off of the second branch pipe 17, which provides double protection. The second solenoid valve 19 receives the control signal of the PLC controller to control the conduction and closing of the second branch pipe 17. The PLC controller determines whether the first branch pipe 11 is faulty based on the flow signal of the first branch pipe 11. When a fault occurs, the normal branch is cut off by controlling the first solenoid valve 13 to close and the second solenoid valve 19 to open, and the backup branch is opened at the same time to achieve smooth switching between the normal branch and the backup branch.

[0050] An argon blowing control process for a continuous casting long nozzle argon seal structure comprises the following steps:

[0051] 1) In the early stage of molten steel casting, open the argon gas source and blow argon into the argon inlet 3. The argon pressure is controlled at 0.5-1.0 MPa and the argon flow rate is 150-250 NL / min. The argon is continuously blown for 5-10 minutes.

[0052] 2) In the middle of molten steel casting, maintain the argon pressure at 0.5-1.0 MPa, adjust the argon flow rate to 50-150 NL / min, and continue to flow for 30-40 minutes;

[0053] 3) At the end of molten steel casting, maintain the argon pressure at 0.5-1.0 MPa, adjust the argon flow rate to 100-200 NL / min, and continue to flow for 1-5 minutes to promote the floating of slag;

[0054] 4) When the ladle stops pouring and the long nozzle is burned and washed, maintain the argon pressure at 0.5-1.0 MPa, adjust the argon flow rate to 50-100 NL / min, and continue to pass it for 1-5 minutes;

[0055] 5) When the long nozzle is burned and cleaned or the long nozzle is replaced, turn off the argon gas source and stop blowing argon.

[0056] The present invention optimizes the argon blowing control system and process, employing different argon blowing techniques according to the steel casting stage. Specifically, a relatively high flow rate is used in the early and late stages of steel casting (although the argon flow rate is significantly reduced compared to before the argon seal structure was improved), while a relatively low flow rate is used in the middle stages of casting. This effectively implements automatic and precise argon control and online intelligent monitoring, avoiding the potential adverse effects of using only a single maximum flow argon blowing mode. This reduces argon consumption and manual operation, while also preventing the impact of the tundish on the steel surface, causing churning and slag curling, thereby improving steel quality.

[0057] The argon blowing control process of the present application is described below through specific examples.

[0058] Example 1

[0059] The technical solution of the present application was implemented in the production of one group of 10-furnace spring steel in a 5-machine 5-flow continuous casting machine. The argon sealing structure and argon blowing control system designed according to the present application were used, and different argon blowing processes were used according to the casting process of each furnace of steel. The specific argon blowing control process was as follows: (1) in the early stage of steel casting, i.e. when the long nozzle sleeve was put on the ladle nozzle, the argon gas source was opened, argon was blown into the long nozzle argon gas chamber 5, the pressure of argon was controlled at 0.8 MPa and remained unchanged, the flow rate of argon was 180 NL / min, and the argon was continuously introduced for 6 min; (2) in the middle stage of steel casting, i.e. when the steel casting was 13 tons, the pressure of argon was 0.8 MPa, the flow rate of argon was adjusted to 80 NL / min, and the argon was continuously introduced for 38 min; (3) in the late stage of steel casting, i.e. when the remaining steel in the ladle was 10 tons, the pressure of argon was controlled at 0.8 MPa and remained unchanged, the flow rate of argon was adjusted to 110 NL / min, and the argon was continuously introduced for 4 min; (4) when the ladle stopped casting and the long nozzle was burned and washed, the pressure of argon was controlled at 0.8 MPa and remained unchanged, the flow rate of argon was adjusted to 70 NL / min, and the argon was continuously introduced for 2 min; (5) when the long nozzle burning and washing was completed or the long nozzle was replaced, the argon gas source was closed and the argon blowing was stopped.

[0060] The argon blowing control and argon blowing effect in the continuous casting process of this group of spring steel were good, the control system did not have abnormal situation alarm, the argon blowing system was normal, and there was no air leakage or air suction in the pipeline. The continuous casting protection casting effect was remarkable, and during the casting process, it was detected that the nitrogen content in the molten steel was 45-55 ppm, the nitrogen content increase was less than 10 ppm, the Als attenuation was within 0.003%, and the T.O in the steel was stably controlled within 10 ppm.

[0061] Example 2

[0062] The difference from Example 1 is that different argon blowing control processes are used on different steel grades.

[0063] The technical scheme is implemented in the production of one group of eight bearing steels by a 5-machine 5-flow continuous casting machine. The argon sealing structure and argon blowing control system designed according to the technical scheme are adopted, and different argon blowing processes are adopted according to the casting process of each steel. The specific argon blowing control process is as follows: (1) in the early stage of the steel casting, that is, when the long nozzle is sleeved with the ladle down nozzle, the argon gas source is opened, argon is blown into the long nozzle argon sealing channel, the pressure of the argon is controlled at 1.0 MPa and remains unchanged, the argon flow is 200 NL / min, and the blowing lasts for 8 min; (2) in the middle stage of the steel casting, that is, when the steel casting is 15 tons, the pressure of the argon is controlled at 1.0 MPa, the argon flow is adjusted to 100 NL / min, and the blowing lasts for 36 min; (3) in the late stage of the steel casting, that is, when the remaining steel in the ladle is 10 tons, the pressure of the argon is controlled at 1.0 MPa, the argon flow is adjusted to 160 NL / min, and the blowing lasts for 4 min; (4) when the ladle stops casting and the long nozzle is burned and washed, the pressure of the argon is controlled at 1.0 MPa, the argon flow is adjusted to 100 NL / min, and the blowing lasts for 2 min; (5) when the long nozzle burning and washing is completed or the long nozzle is replaced, the argon gas source is closed, and the argon blowing is stopped.

[0064] The argon blowing control and argon blowing effect are good in the continuous casting process of the bearing steels in the group, the control system does not appear abnormal situation alarm, the argon blowing system is normal, and there is no air leakage or air suction in the pipeline. The continuous casting protection casting effect is remarkable, and through detection, the nitrogen content in the molten steel is 35-50 ppm, the nitrogen content increase is less than 6 ppm, the Als attenuation is within 0.002%, and the T.O in the steel is stably controlled within 6 ppm.

[0065] Comparative Example 1

[0066] The difference between Example 1 and Comparative Example 1 is that the argon sealing structure and argon blowing control system and argon blowing process designed according to the technical scheme are not adopted, the argon sealing structure is as shown in Figure 1 and Figure 2 , and the argon blowing control mode adopts manual control in a large flow mode. The specific argon blowing control process is as follows: before the long nozzle is sleeved with the ladle down nozzle, the argon gas source is opened manually, argon is blown into the long nozzle argon sealing channel, the pressure of the argon is controlled at 1.0 MPa and remains unchanged, the argon flow remains unchanged at 300 NL / min, until the production of the ten steels in the group is completed, the argon gas source is closed, and the argon blowing is stopped.

[0067] During the continuous casting process of this spring steel, argon blowing was manually controlled using a single argon pressure and flow rate. The effectiveness of the argon blowing process could not be monitored online. Furthermore, due to the high argon flow rate, the slag surface churned in the tundish impact zone. The continuous casting protective casting effect was relatively poor. During the casting process, sampling revealed that the nitrogen content in the molten steel was between 55 and 65 ppm, with a nitrogen increase of 10 to 20 ppm. Al2O3 attenuation was between 0.003% and 0.005%, and TO in the steel was between 10 and 15 ppm. The resulting molten steel was of poor quality, failing to meet the standards of Example 1.

[0068] Comparative Example 2

[0069] The difference from Example 1 is that the argon sealing structure designed by the present invention is not adopted, but the argon blowing control system designed by the present invention is adopted, and the argon blowing process is appropriately adjusted. The argon sealing structure is as follows: Figure 1 and Figure 2 As shown in FIG, the argon blowing control process is as follows: (1) in the early stage of molten steel casting, that is, when the ladle outlet is covered with the long nozzle, the argon gas source is turned on and argon is blown into the argon gas chamber 5 of the long nozzle. The argon pressure is controlled at 1.0 MPa and the argon flow rate is 300 NL / min, and the argon is continuously blown for 6 minutes; (2) in the middle stage of molten steel casting, that is, when 13 tons of molten steel is cast, the argon pressure is 1.0 MPa, the argon flow rate is adjusted to 150 NL / min, and the argon is continuously blown. (3) At the end of molten steel casting, that is, when there are 10 tons of molten steel remaining in the ladle, the pressure of argon is 1.0 MPa, the argon flow rate is adjusted to 180 NL / min, and it is continuously introduced for 4 minutes; (4) When the ladle stops pouring and the long nozzle is burned and cleaned, the pressure of argon is 1.0 MPa, the argon flow rate is adjusted to 100 NL / min, and it is continuously introduced for 2 minutes; (5) After the burning and cleaning of the long nozzle is completed or the long nozzle is replaced, the argon source is turned off and the argon blowing is stopped.

[0070] During the continuous casting process of this group of spring steel, the original nozzle argon sealing structure and the argon blowing control system of the present invention were used. In order to improve the argon sealing effect, the argon blowing process was appropriately adjusted, and the argon pressure and flow were appropriately increased. During the production process, in the case of a large argon flow in the early stage of casting, occasional churning occurred on the slag surface in the impact zone of the tundish. In other casting stages, after the argon flow was reduced, the slag surface in the impact zone was normal. Compared with Comparative Example 1, not only argon consumption and manual labor were saved, but the protective casting effect was also improved to a certain extent. However, compared with Example 1, the argon sealing effect was not significant, and the continuous casting protective casting was relatively poor. Through sampling and testing, it was found that the nitrogen content in the molten steel was 50-60ppm, the nitrogen content increased by 8-15ppm, the Als attenuation was 0.002%-0.004%, and the TO in the steel was controlled at 8-12ppm. The quality of the obtained molten steel was improved compared with Comparative Example 1, but it did not reach the quality level of the molten steel in Example 1.

[0071] Comparative Example 3

[0072] The difference from Example 1 is that the argon blowing control system and control process designed according to the application is not adopted, but the argon sealing structure designed according to the application is adopted, and the argon sealing structure adopts Figure 3 and Figure 4 The argon blowing control mode is controlled by manual operation in a large flow mode. The specific argon blowing control process is that before the long nozzle sleeve is put on the ladle down nozzle, the argon gas source is opened manually, argon is blown into the long nozzle argon sealing passage, the pressure of the argon is controlled at 1.0 MPa and remains unchanged, the argon flow remains at 300 NL / min, until the group of 10 furnace steel casting production is completed, the argon gas source is closed, and the argon blowing is stopped.

[0073] During the spring steel continuous casting process, the argon sealing structure designed according to the application is adopted, and the argon blowing is controlled by manual operation in a large argon flow. During the production process, although the argon flow is large, there is no slag surface turbulence in the tundish impact area, which shows that under the argon sealing structure designed according to the application, the argon flow is smooth and uniform, and the argon sealing effect and the protection casting effect are good during the casting process. However, compared with Example 1, the argon consumption cost and the manual labor intensity are increased, and the argon blowing effect cannot be monitored online in real time, and when abnormal conditions such as gas leakage and gas interruption occur, online real-time early warning and correction cannot be realized, and there is a certain degree of risk in the stable operation of the system, thereby seriously affecting the quality stability. During the production process, no abnormal conditions such as gas leakage or gas interruption occurred through the arrangement of special process monitoring, the nitrogen content in the molten steel was 45-55 ppm through sampling detection, the nitrogen content increase was less than 10 ppm, the Als attenuation was controlled within 0.003%, the T.O in the steel was controlled within 10 ppm, and the quality of the molten steel obtained was equivalent to that of Example 1.

[0074] In summary, the application utilizes the principle of fluid mechanics, innovatively designs the long nozzle argon sealing structure, i.e. the annular groove passage design, realizes the uniform distribution of argon in the gas chamber, makes the argon in the long nozzle bowl area overflow uniformly in the circumferential direction, and greatly improves the argon sealing effect. Moreover, based on the above improvement, the application also innovatively designs the corresponding optimization of the argon blowing control system and process, adopts different argon blowing processes according to the molten steel casting stage, and effectively realizes the automatic and accurate control and online intelligent monitoring of argon, which on the one hand reduces the argon consumption and manual operation, and on the other hand avoids the occurrence of tundish impact molten steel surface turbulence and slag entrapment, and improves the molten steel quality.

[0075] The above is only to illustrate some principles of the application by means of figures, and this specification is not intended to limit the application to the specific structure and application range shown and described, so all possible corresponding modifications and equivalents belong to the patent scope applied for by the application.

Claims

1. A continuous casting shroud argon seal structure, comprising a shroud body and a shell covering the periphery of its bowl, wherein an argon gas inlet is provided on the shell, characterized in that: An annular groove is provided on the outer periphery of the bowl portion, and the volume of the annular groove gradually increases from the argon gas inlet to the opposite side thereof.

2. The argon seal structure for continuous casting shroud according to claim 1, characterized in that: A narrow space is formed between the shell and the shroud body, and an argon gas chamber is formed between the narrow space and the annular groove.

3. The argon seal structure for continuous casting shroud according to claim 1, characterized in that: The depth and width of the annular groove gradually increase from the argon gas inlet to the opposite side thereof.

4. The argon seal structure for continuous casting shroud according to claim 3, characterized in that: The depth of the annular groove is 3-8 mm, and the width of the annular groove is 3-10 mm.

5. The argon seal structure for continuous casting shroud according to claim 1, characterized in that: The long nozzle body is made of aluminum-magnesium-carbon components, and the raw material components and their weight percentages respectively include: 35-45% fused corundum, 15-25% fused magnesia, 15-25% flaky graphite, 10-20% activated alumina, 5-10% fused spinel and 2-4% pure calcium aluminate cement.

6. An argon blowing control system for the argon seal structure of a continuous casting shroud according to any one of claims 1 to 5, characterized in that: It includes an argon gas pipeline system and an electrical control system. The argon gas pipeline system includes an argon gas source and a normal branch and a backup branch connected thereto. The electrical control system includes a PLC controller, a host computer, a continuous casting automation system and a molten steel weighing system. The PLC controller communicates with the host computer via industrial Ethernet, receives commands from the host computer, and transmits pressure and flow signals in the argon gas pipeline system to the host computer; The molten steel weighing system collects and sends the weight of the molten steel in the ladle to the continuous casting automation system. The continuous casting automation system communicates with the host computer via industrial Ethernet. The PLC controller receives commands from the host computer to adjust the argon flow in the normal branch or control the opening of the backup branch.

7. The argon blowing control system according to claim 6, characterized in that: The air inlet ends of the normal branch and the backup branch are connected to the argon gas source through an air source inlet pipe, and a first manual ball valve and a pressure gauge are connected to the air source inlet pipe; the air outlet ends of the normal branch and the backup branch are connected to the argon gas inlet through an air source outlet pipe, and a pressure transmitter is connected to the air source outlet pipe.

8. The argon blowing control system according to claim 7, characterized in that: The normal branch includes a first branch pipeline and a second manual ball valve, a first solenoid valve, a pressure reducing valve, a flow regulating valve and a mass flow meter connected in series along the flow direction of argon gas. The pressure gauge, pressure transmitter and mass flow meter are connected to the input end of the PLC controller, and the output end of the PLC controller is connected to the flow regulating valve and the pressure reducing valve. The output end of the PLC controller is connected to the first solenoid valve to control the conduction and closing of the first branch pipeline.

9. The argon blowing control system according to claim 6, characterized in that: The backup branch includes a second branch pipeline and a third manual ball valve, a second solenoid valve and a manual regulating valve connected in series along the direction of argon flow. The second solenoid valve receives a control signal from the PLC controller to control the conduction and closing of the second branch pipeline.

10. An argon blowing control process for the argon sealing structure of a continuous casting shroud according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) In the early stage of molten steel casting, open the argon gas source and blow argon into the argon inlet. The argon pressure is controlled at 0.5-1.0 MPa and the argon flow rate is 150-250 NL / min. It is continuously blown for 5-10 minutes. 2) In the middle of molten steel casting, maintain the argon pressure at 0.5-1.0 MPa, adjust the argon flow rate to 50-150 NL / min, and continue to flow for 30-40 minutes; 3) At the end of molten steel casting, maintain the argon pressure at 0.5-1.0 MPa, adjust the argon flow rate to 100-200 NL / min, and continue to flow for 1-5 minutes to promote the floating of slag; 4) When the ladle stops pouring and the long nozzle is burned and washed, maintain the argon pressure at 0.5-1.0 MPa, adjust the argon flow rate to 50-100 NL / min, and continue to flow for 1-5 minutes; 5) When the long nozzle is burned and cleaned or the long nozzle is replaced, turn off the argon gas source and stop blowing argon.

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