Continuous casting middle first furnace ladle cover argon blowing method capable of achieving automatic control

Abstract

The invention relates to a continuous casting middle first furnace ladle cover argon blowing method capable of achieving automatic control. The method comprises the following steps that firstly, a gas blowing-in embedded part is welded to one side of each ladle cover of a tundish, and secondly, an argon blowing-in system control cabinet is additionally arranged on a tundish vehicle. And 3, before the tundish is preheated on the platform, the control system and the gas embedded part are connected through a metal hose through a pipeline. And 4, automatic argon blowing of the tundish in the first furnace.

Description

Technical Field

[0001] The present invention relates to a method for argon blowing, in particular to an argon blowing method for the cover of the first ladle in continuous casting that can achieve automatic control, belonging to the technical field of continuous casting in iron and steel metallurgy. Background Art

[0002] In current metallurgical enterprises, the requirements for the purity of molten steel supplied for continuous casting are getting higher and higher. A large number of devices and auxiliary materials have been invested in the previous processes of continuous casting, including converters and refining processes, to ensure the purity of the molten steel supplied to continuous casting. However, due to the technological limitations of continuous casting, when a new tundish is used for casting each time, the inclusions formed by the reaction of the air in the new tundish with aluminum in the molten steel will cause the purity of the molten steel in the first ladle of continuous casting to deteriorate. Currently, most domestic continuous casting tundishes adopt sealing means to prevent the molten steel in the tundish from being polluted by air, thereby affecting the purity of the molten steel. Such sealing methods include protective sleeves from the ladle to the tundish with argon blowing protection, tundish cover sealing, increasing argon blowing to displace air and reduce pollution, and adopting the method of adding covering agents or carbonized rice balls to isolate air for protection. However, in the continuous casting process, when a new tundish is used, since the air in the tundish cannot be removed, the molten steel from the ladle will surely come into contact with air after injection, resulting in secondary oxidation and pollution. Therefore, in most domestic steel plants currently, when producing high-quality and high-requirement steel grades, a certain length of slab is cut off for the first slab of the new continuous casting tundish. This is a huge loss for the quality and cost of the steel plant. Since there is inevitably air in the new tundish during the first pouring of the first ladle, the molten steel injected is polluted. Subsequently, through the addition of covering agents, air can be isolated during normal production to prevent air from polluting the molten steel. Therefore, during the entire pouring process of the first ladle of the continuous casting tundish, the residual air pollution in the tundish to the molten steel is the most important pollution link.

[0003] Based on the above situation, a complete and scientific technical solution or device must be available to reduce the pollution of the molten steel in the tundish by the air in the tundish when the molten steel is injected into the first ladle.

[0004] Through the applicant's retrieval, currently, to reduce the pollution of the molten steel in the tundish by the air in the tundish during the first pouring of the tundish in the domestic industry, the tundish cover is sealed, and then an inert gas (argon) is blown into the cover to reduce the pollution of the molten steel. For example, in the "Device and Method for Sealed Argon Blowing Protection of Continuous Casting Tundish" with the application number 201610140768.8, the innovation is mainly concentrated on the argon blowing device of the cover.

[0005] The "Method for Reducing Nitrogen Increase in Molten Steel during Continuous Casting" with the application number 201810178824.6 mainly replaces the atmosphere in the tundish with inert gas and seals the tundish to ensure that the oxygen content in the tundish is <0.1%; before the start of casting for each furnace, the bowl part of the long nozzle is sealed, and during continuous casting, the bowl part of the long nozzle of the ladle is purged with an oxygen lance to ensure that the inside of the bowl is clean; after the start of casting in the ladle, when the weight of the molten steel injected into the tundish reaches 30 - 40 tons, a high-alkalinity covering agent is added, which belongs to the relatively conventional sealed protection casting technology in the industry.

[0006] The "Continuous Casting Tundish Micro-Positive Pressure Argon Sealing Casting Device, Control System and Method" with the application number 202010437198.5 pre-buries an annular argon blowing pipe along the outer peripheral direction of the upper edge of the tundish, and a plurality of argon blowing nozzles are arranged inside the annular argon blowing pipe. By introducing argon into the annular argon blowing pipe and spraying it into the tundish through the argon blowing nozzles, during the molten steel casting process, the flow rate gear of argon is adjusted according to the net weight of the molten steel and the casting process, and the molten steel casting process is monitored in real time, so that the inside of the tundish always forms a micro-positive pressure sealed state during the casting process, which can also effectively prevent the molten steel from contacting with air and causing secondary oxidation, and effectively improve the quality of the molten steel.

[0007] The "Continuous Casting Tundish Cover and Its Blowing Protection Casting Method" with the application number 202111122554.5 discloses a continuous casting tundish cover and determines the specific blowing flow rate and time based on the capacity of the tundish, and adopts a combined blowing process of blowing argon gas in the early stage of casting + blowing CO2 in the stable casting stage, which helps to make the injected protective gas fill the tundish more efficiently and uniformly, enhance the protection casting effect, and at the same time adopts the method of blowing CO2 in the stable casting stage.

[0008] As described above, through the inventor's retrieval and query, in the domestic industry, for the argon blowing of the tundish cover in the first furnace, it mainly focuses on the setting of the argon blowing device and the control of the blowing flow rate of the tundish cover. With the continuous popularization of automation and less manpower at the continuous casting site, however, this blowing control method relies on manual experience to control the valves and the flow rate. Manual control not only has poor operation stability, but also the consumption of inert gas cannot be accurately controlled, resulting in unstable cost control of the continuous casting process. This way of relying on manual experience to judge and control the argon blowing of the tundish cover in the first furnace has obviously not met the requirements of modern continuous casting. Summary of the Invention

[0009] The present invention precisely aims at the problems existing in the prior art and provides an automatic control method for argon blowing of the tundish cover in the first furnace of continuous casting, which is mainly realized through the following steps:

[0010] An argon gas pipeline blowing quick-connection device and a gas blowing embedded part are added to the tundish cover. An argon gas blowing control cabinet system is added to the tundish carriage. The control cabinet is connected to the PLC in the tundish carriage through industrial Ethernet to record the argon gas flow rate and monitor the argon gas usage. And its value is directly fed back and saved to the continuous casting level 1 system through a data line, which can achieve precise control of the replacement gas in the tundish, provide historical traceable data for the amount of blown-in argon gas, ensure the precise controllability of the blown-in argon gas amount, and thus achieve the optimal cost of inert gas.

[0011] By collecting information such as the preheating and baking status of the tundish, the position information of the tundish carriage, the opening degree information of the ladle slide plate, and the weight information of the new tundish, the inert gas blowing control system is managed to achieve automatic control.

[0012] Through data transmission and feedback and saving to the continuous casting level 1 system, precise control of the replacement gas in the tundish is achieved, providing historical traceable data for the amount of blown-in gas, ensuring the optimization of the blown-in gas amount, and achieving precise controllability of the inert gas cost.

[0013] In order to achieve the above object, the technical solution of the present invention is as follows. A method for blowing argon into the first furnace cover of a continuous casting tundish that can achieve automatic control mainly adopts the following solutions:

[0014] Step 1. Weld a gas blowing embedded part on one side of each tundish cover. The pipe diameter of the embedded part is designed to be 50%-80% of the gas pipeline; the direction of the blowing hole forms a 30° angle with the tundish wall. A quick-connection device is reserved outside the embedded part to facilitate quick connection with the pipeline on the tundish carriage.

[0015] Step 2. Add an argon gas blowing system control cabinet to the tundish carriage.

[0016] 2.1 A flow meter, a pressure reducing valve, a pressure gauge, a pressure sensor, a quick cut-off valve, a ball valve, and a globe valve are designed and installed in the argon gas blowing control cabinet.

[0017] 2.2 Bypass pipelines are added at the front and rear ends of the argon gas blowing control cabinet, and the bypass pipelines can be used to restore the cover blowing function when the system control is abnormal.

[0018] 2.3 The control cabinet is connected to the PLC in the tundish carriage through industrial Ethernet to record the argon gas flow rate and monitor the argon gas usage. And its value is directly fed back and saved to the continuous casting level 1 system through a data line, which can achieve precise control of the replacement gas in the tundish, provide historical traceable data for the amount of blown-in gas, ensure the optimization of the blown-in gas amount, and thus achieve the controllability of the inert gas cost.

[0019] Step 3. Before the tundish is lifted for preheating, connect the control system and the gas embedded part pipeline through a metal hose.

[0020] Step 4. Automatic argon blowing for the first ladle in the tundish

[0021] 4.1 Collect the baking status signal and baking arm position signal of the tundish carriage

[0022] 4.2 After receiving the command that the baking of the tundish carriage is completed, wait for the baking arm position signal to reach the "high position"

[0023] 4.3 Start the control system cut-off valve and blow in argon gas

[0024] 4.4 Control the argon gas flow rate according to the process setting requirements

[0025] 4.5 Collect the position information of the tundish carriage

[0026] 4.6 After receiving that the tundish carriage reaches the "pouring position", collect the information that the ladle slide gate is opened

[0027] 4.7 After receiving the information that the slide gate is opened, collect the tundish tonnage information and start timing

[0028] 4.8 When the tundish tonnage reaches the process required tonnage or the cumulative timing time reaches the process requirement, close the gas cut-off valve and stop blowing argon gas

[0029] 4.9 The automatic control process ends

[0030] Compared with the prior art, the present invention has the following advantages. Using the method of the present invention for the automatic control of argon blowing for the first ladle cover of the new tundish in continuous casting can realize the automatic argon blowing protection and closed pouring throughout the entire process of continuous casting starting. It not only ensures that the molten steel in the first ladle of starting casting is not polluted, but also avoids manual intervention, reduces the labor intensity of workers and improves the control accuracy of argon blowing. When Meishan Steel's steelmaking plant conducted experiments recently, after adopting this device and method, through actual detection, the oxygen ratio in the new tundish after 3 minutes of argon blowing before starting casting decreased from 18% to 5%. The first ladle nitrogen increase index, which best reflects the purity of molten steel, decreased from the original 5 PPM to less than 3 PPM now (see the following table). At the same time, due to the realization of automatic control, the operation time of workers is reduced, and the downtime for tundish change and starting casting is also reduced by 0.5 min, which well ensures the stable and smooth starting casting of the first ladle in continuous casting.

[0031] Statistics of the first ladle nitrogen increase in Meishan Steel

[0032] Counting times Project name Unit Actual performance 1 Nitrogen increase in the first ladle of continuous casting tundish ppm 2.72 2 Nitrogen increase in the first ladle of continuous casting tundish ppm 4.28 3 Nitrogen increase in the first ladle of continuous casting tundish ppm 2.12 4 Nitrogen increase in the first ladle of continuous casting tundish ppm 2.56 5 Nitrogen increase in the first ladle of continuous casting tundish ppm 3.62 6 Nitrogen increase in the first ladle of continuous casting tundish ppm 2.21 7 Nitrogen increase in the first ladle of continuous casting tundish ppm 2.91 8 Nitrogen increase in the first ladle of continuous casting tundish ppm 3.3 9 Nitrogen increase in the first ladle of continuous casting tundish ppm 2.2 10 Nitrogen increase in the first ladle of continuous casting tundish ppm 2.67 11 Nitrogen increase in the first ladle of continuous casting tundish ppm 3.84 12 Nitrogen increase in the first ladle of continuous casting tundish ppm 2.23 13 Nitrogen increase in the first ladle of continuous casting tundish ppm 2.32 14 Nitrogen increase in the first ladle of continuous casting tundish ppm 3.41 15 Nitrogen increase in the first ladle of continuous casting tundish ppm 2.53 Description of the drawings

[0033] Figure 1 : Automatic argon blowing system for the tundish cover

[0034] Figure 2 Flow chart of automatic argon blowing control for the first ladle cover

[0035] In the figure: 1. Flowmeter, 2. Pressure reducing valve, 3. Pressure gauge, 4. Quick cut-off valve, 5. Hand valve, 6. External argon gas access, 7. Access to the ladle cover. Specific implementation mode

[0036] To deepen the understanding of the present invention, the following detailed description is given in conjunction with the accompanying drawings for this embodiment.

[0037] Embodiment 1: Refer to Figure 1 、 Figure 2 , a continuous casting tundish first furnace ladle cover argon blowing system capable of realizing automatic control. This system is mainly implemented by the following scheme:

[0038] Step 1. Weld the gas blowing embedded parts on one side of each ladle cover of the tundish. The pipe diameter of the embedded parts is designed to be 50%-80% of the gas pipeline; the direction of the blowing hole forms a 30° angle with the tundish wall. A quick connection device is reserved outside the embedded parts to facilitate the quick connection with the pipeline on the tundish car.

[0039] Step 2. Add an argon gas blowing system control cabinet on the tundish car.

[0040] 2.1 A flowmeter, a pressure reducing valve, a pressure gauge, a pressure sensor, a quick cut-off valve, a ball valve, and a globe valve are designed and installed in the argon gas blowing control cabinet.

[0041] 2.2 Bypass pipelines are added at the front and rear ends inside the argon gas blowing control cabinet, and the ladle cover blowing function can be restored by using the bypass pipelines when the system control is abnormal.

[0042] 2.3 The control cabinet is connected to the PLC inside the tundish car through the industrial Ethernet to record the argon gas flow and monitor the argon gas usage. And its value is directly fed back and saved to the continuous casting first-level system through the data line, which can realize the precise control of the replacement gas inside the tundish, and provides historical traceable data for the amount of the blown-in gas, ensuring the optimization of the gas blowing amount, and thus realizing the controllability of the inert gas cost.

[0043] Step 3. Before the tundish is preheated on the platform, connect the control system and the gas embedded part pipeline through a metal hose.

[0044] Step 4. Automatic argon blowing for the first furnace of the tundish

[0045] 4.1 Collect the tundish car baking state signal and the baking arm position signal

[0046] 4.2 After receiving the tundish car baking end command, wait for the baking arm position signal to reach "high position"

[0047] 4.3 Start the cut-off valve of the control system and blow in argon gas

[0048] 4.4 Control the argon gas flow according to the process setting requirements

[0049] 4.5 Collect the position information of the tundish car

[0050] 4.6 After receiving the information that the tundish car reaches the "pouring position", collect the information of the ladle slide plate opening

[0051] 4.7 After receiving the information of the slide plate opening, collect the tundish tonnage information and start timing

[0052] 4.8 When the tundish tonnage reaches the process requirement tonnage or the cumulative timing time reaches the process requirement, close the gas cut-off valve and stop the argon gas blowing

[0053] 4.9 The automatic control process ends

[0054] Specific embodiment: For a double-strand slab continuous caster in a certain factory, the tundish cover is divided into 3 combinations. The process requires argon blowing inside the tundish before the tundish tonnage reaches 40 tons for a new tundish, or argon blowing inside the tundish must be implemented within 30 minutes after the tundish stops baking. The diameter of the connecting hose of the tundish cover is 45 mm. According to this automatic argon blowing system, the implementation method is as follows:

[0055] 1. Weld the gas blowing embedded parts on one side of each tundish cover. The designed diameter of the embedded parts is 50%-80% of the gas connection pipeline. In this scheme, 75% is selected, so the embedded parts with a diameter of 34 mm are used; the direction of the blowing hole forms a 30° angle with the tundish wall. A quick connection device is reserved outside the embedded parts for quick connection with the pipeline on the tundish car

[0056] 2. Add an argon blowing system control cabinet on the tundish car

[0057] 2.1 The argon blowing control cabinet is designed and installed with a flow meter, a pressure reducing valve, a pressure gauge, a pressure sensor, a quick cut-off valve, a ball valve, and a globe valve. The on-site argon control box uses a stainless steel box with a thickness of 2 mm and an IP54 protection level. The internal piping of the cabinet Φ45*3.5 is all made of stainless steel seamless steel pipes. The mass flow meter has a diameter of Φ45*3.5, a normal flow rate of 270 m3 / h, a maximum flow rate of 350 m3 / h, and a pressure of 0.8-1.0 MPa; the self-operated pressure reducing valve has a diameter of Φ45*3.5, a pre-valve pressure of 0.8-1.0 MPa, and a post-valve pressure of 0.6-0.8 MPa; the pressure gauge is 0-1.6 MPa; the pressure sensor is 0-1.0 MPa, output: 4-20 mA; the quick cut-off valve has a diameter of Φ45*3.5 and a flow rate of 350 Nm3 / h, a pressure of 0-0.8 MPa; the quick cut-off valve has a diameter of DN15 and a pressure of 0-0.8 MPa

[0058] 2.2 Add bypass pipelines at the front and rear ends inside the argon blowing control cabinet to restore the cover blowing function using the bypass pipeline when the system control is abnormal

[0059] 2.3 The control cabinet is connected to the PLC in the tundish car through industrial Ethernet, records the argon flow rate, and monitors the argon usage. It directly feeds back and saves its value to the continuous casting level 1 system through a data cable, realizes the precise control of the replacement gas inside the tundish, provides historical traceable data for the amount of blown gas, ensures the optimization of the gas blowing amount, and thus realizes the controllability of the argon cost.

[0060] 4. Before the tundish is preheated on the platform, connect the control system and the gas embedded part pipeline through a metal hose.

[0061] 4. Automatic argon blowing for the first heat of the tundish

[0062] 4.1 Collect the baking status signal and the baking arm position signal of the tundish car

[0063] 4.2 After receiving the command for the end of the baking of the tundish car, wait for the baking arm position signal to reach the "high position"

[0064] 4.3 Start the cut-off valve of the control system and blow in argon

[0065] 4.4 Control the argon gas flow rate at 270 m3 / h according to the process setting requirements

[0066] 4.5 Collect the position information of the tundish car

[0067] 4.6 After receiving that the tundish car has reached the "casting position", collect the information on the opening of the ladle slide plate

[0068] 4.7 After receiving the information on the opening of the slide plate, collect the tundish tonnage information and start timing

[0069] 4.8 When the tundish tonnage reaches the process requirement of 40 tons or the cumulative timing time reaches 30 minutes, then close the gas cut-off valve and stop blowing argon gas.

[0070] 4.9 The automatic control process ends.

[0071] It should be noted that the above embodiments are not used to limit the protection scope of the present invention. Equivalent transformations or substitutions made on the basis of the above technical solutions all fall within the protection scope of the claims of the present invention.

Claims

1. An argon blowing method for the tundish first furnace cover that can achieve automatic control, Characterized in that, The method includes the following steps: Step 1. Weld the gas injection embedded parts on one side of each tundish cover. Step 2. Add an argon injection system control cabinet on the tundish car. Step 3. Before the tundish is preheated on the stage, connect the control system and the gas embedded part pipeline through a metal hose. Step 4. Automatically blow argon into the first furnace of the tundish.

2. The argon blowing method for the tundish first furnace cover that can achieve automatic control according to claim 1, Characterized in that, In step 1, weld the gas injection embedded parts on one side of each tundish cover. The pipe diameter of the embedded part is designed to be 50%-80% of the gas pipeline; the direction of the injection hole forms a 30° angle with the tundish wall, and a quick connection device is reserved outside the embedded part for quick connection with the pipeline on the tundish car.

3. The argon blowing method for the tundish first furnace cover that can achieve automatic control according to claim 2, Characterized in that, In step 2, add an argon injection system control cabinet on the tundish car, specifically as follows: 2.1 A flow meter, a pressure reducing valve, a pressure gauge, a pressure sensor, a quick cut-off valve, a ball valve, and a globe valve are designed and installed in the argon injection control cabinet. 2.2 Bypass pipelines are added at the front and rear ends of the argon injection control cabinet. When the system control is abnormal, the bypass pipelines can be used to restore the cover blowing function. 2.3 The control cabinet is connected to the PLC in the tundish car through the industrial Ethernet to record the argon flow rate, monitor the argon usage, and directly feedback and save its value to the continuous casting level 1 system through the data line to achieve precise control of the replacement gas in the tundish, provide historical traceable data for the amount of blown-in gas, ensure the optimization of the gas blowing amount, and thus achieve controllable inert gas costs.

4. The argon blowing method for the tundish first furnace cover that can achieve automatic control according to claim 3, Characterized in that, In step 4, automatically blow argon into the first furnace of the tundish, specifically as follows: 4.1 Collect the tundish car baking status signal and the baking arm position signal. 4.2 After receiving the tundish car baking end command, wait for the baking arm position signal to reach "high position". 4.3 Start the control system cut-off valve and blow in argon. 4.4 Control the argon gas flow rate according to the process setting requirements. 4.5 Collect the tundish car position information. 4.6 After receiving that the tundish car reaches the "pouring position", collect the ladle slide gate opening information. 4.7 After receiving the slide gate opening information, collect the tundish tonnage information and start timing. 4.8 When the tundish tonnage reaches the process requirement tonnage or the cumulative timing time reaches the process requirement, close the gas cut-off valve and stop the argon gas blowing. 4.9 The automatic control process ends.

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