Four-section type high-low gun position operation method for controlling molten pool state in model steelmaking process

Abstract

The invention belongs to the technical field of iron and steel smelting, and particularly discloses a four-section type high-low lance position operation method for controlling the state of a molten pool in the model steelmaking process, which comprises the following steps of: firstly, adopting high lance position ignition at the initial stage of converter smelting; adjusting the lance position of an oxygen lance to 1800mm in a carbon-oxygen reaction stage, and adjusting the lance position to a low lance position in a dephosphorization stage; and finally, when the oxygen supply amount is left to be 1200 m < 3 >, the lance position of the oxygen lance is reduced to 1100 mm, and the oxygen flow and the oxygen supply pressure are adjusted until oxygen injection is finished. Aiming at the problem that oxygen lance position control depends on experience judgment of an operator, non-quantitative subjective judgment logic which is difficult to recognize and process by a computer automatic control system is standardized and quantified, so that a computer model can be directly executed, and the problem that traditional oxygen lance position control depends on experience judgment of the operator, so that the accuracy of oxygen lance position control is improved is solved. The operation methods are different from one person, so that the smelting result of the same steel grade fluctuates, and the consistency of the product quality is seriously influenced.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting technology, specifically to a four-stage high and low gun position operation method for controlling the state of the molten pool during model steelmaking. Background Technology

[0002] In steelmaking, converter steelmaking is a core process. Using molten iron as the main raw material, oxygen or a mixture of oxygen and inert gases is blown into the converter. The process utilizes the physical and chemical heat of the molten iron, such as the carbon-oxygen reaction and the silicon-manganese oxidation reaction, to remove harmful impurities like carbon, silicon, manganese, phosphorus, and sulfur from the molten iron at high temperatures. This process also adjusts the composition and temperature of the molten steel, ultimately producing steel billets that meet the required specifications. The stability of the smelting process, the efficiency of key indicator control, and the degree of operational standardization directly determine the quality of the molten steel, production costs, and production safety. Due to its advantages of fast smelting speed, high production efficiency, and low cost, this process is widely used in the production of various types of steel, including plain carbon steel, low-alloy steel, and medium-to-high alloy steel.

[0003] In the converter steelmaking process, the oxygen lance is the core equipment for blowing oxygen into the molten pool. The position of the oxygen lance is the vertical distance between the oxygen lance nozzle and the surface of the molten metal in the pool. It directly determines the impact depth and stirring effect of the oxygen jet on the molten pool. It is a key process parameter that affects the steelmaking reaction efficiency, the uniformity of molten steel composition, the oxidizing properties of slag, and the service life of the equipment. Its value needs to be dynamically adjusted according to the composition of molten iron, furnace type, etc., so as to optimize the steelmaking reaction efficiency.

[0004] Traditional oxygen lance position control typically relies on operator experience and judgment, manually adjusting the lance height by observing visual phenomena such as the color of the molten pool flame and splashing at the furnace mouth. Some steel mills use semi-automatic control based on preset process curves, setting fixed lance position ranges according to steelmaking stages such as the initial, middle, and final stages of blowing, and making step-by-step adjustments according to time nodes. Because oxygen lance position control depends on operator experience and judgment, different operators have significantly different judgment standards. This subjectivity can easily lead to fluctuations in operation during the initial ignition stage, affecting the uniformity of the smelting rhythm. Secondly, the specific height to which the lance is raised or lowered, and the duration to which the high lance position should be maintained, lack quantifiable control standards. This can lead to judgment errors during operation, causing uncontrolled reactions, resulting in splashing or prolonged smelting cycles, thereby increasing production costs and safety risks.

[0005] In summary, it is necessary to design a four-stage high and low lance position operation method for controlling the state of the molten pool during the model steelmaking process. This method addresses the problem that traditional oxygen lance position control relies on the operator's experience and judgment, leading to variations in operation methods from person to person. This results in fluctuations in the smelting results of the same steel grade, which seriously affects the consistency of product quality. Summary of the Invention

[0006] The purpose of this invention is to provide a four-stage high and low lance position operation method for controlling the state of the molten pool during model steelmaking, in order to solve the problem that traditional oxygen lance position control relies on the operator's experience and judgment, resulting in different operation methods from person to person, which causes fluctuations in the smelting results of the same steel grade and seriously affects the consistency of product quality.

[0007] To achieve the above objectives, the basic solution provided by this invention is: a four-stage high and low lance position operation method for controlling the state of the molten pool during model steelmaking, comprising the following steps: S1: "High" lance position smelting and ignition stage: First, the desulfurized and slag-removed molten iron is loaded into the converter. Then, the operator remotely adjusts the height of the oxygen lance through the control system so that the oxygen lance is 2200mm away from the surface of the molten iron. Then, oxygen blowing begins and the molten iron in the converter is heated. When the oxygen supply reaches 5% of the total oxygen supply, slag is added into the converter. S2: High-position carbon-oxygen reaction stage: When the oxygen supply from the oxygen lance reaches 12% of the total oxygen supply at a height of 1800mm above the molten iron, the operator adjusts the oxygen supply pressure to 0.85MPa and the oxygen flow rate to 26000m³ / h. 3 / h, and when the oxygen supply reaches 15% of the total oxygen supply, the remaining slag is added into the converter; S3: Low-position dephosphorization control stage: When the oxygen supply reaches 45% of the total oxygen supply, the operator adjusts the oxygen lance position to 1600mm from the liquid surface through the control system and continues blowing oxygen until the remaining oxygen supply is 1200mm. 3 At this time, the operator lowers the oxygen lance position to 1100mm via the control system; S4: "Low" lance position slag drying and splashing stage: when the oxygen supply is 300m³ remaining 3 At that time, lower the oxygen lance position to 1000mm and adjust the oxygen flow rate to 26000m³. 3 / h, while increasing the oxygen supply pressure to 0.9MPa until the oxygen injection ends.

[0008] The beneficial effects of the present invention are as follows: (1) The present invention solves the problem that the traditional oxygen lance position control relies on the experience judgment of the operator, which leads to different operating methods and fluctuations in the smelting results of the same steel grade, seriously affecting the consistency of product quality. This method transforms the traditional smelting opening and ignition stage, carbon-oxygen reaction stage, dephosphorization control stage and slag drying and splashing stage that rely on the worker's visual observation of flame brightness and subjective judgment into a precise quantitative oxygen lance position, oxygen supply pressure, oxygen supply amount and slag amount that does not require a computer model to judge whether the ignition is normal; (2) The present invention adopts a four-stage lance position operation of "high-high-low-low", and in the second stage "high lance" The "high gun position" combined with a lower oxygen supply pressure delays the reaction and accumulates ferrous oxide in the early stage of carbon-oxygen reaction, which not only prevents splashing, but also creates conditions for subsequent dephosphorization, thus achieving a balance between dephosphorization efficiency and process stability; (3) Through the design of "high gun position to ensure sufficient ignition", "early slag formation and delayed heating to avoid the period of intense carbon-oxygen reaction" and "low gun position to ensure sufficient stirring of the molten pool and promote dephosphorization effect", there is no need for computer models to judge whether the ignition is normal in the early stage of converter smelting, when the carbon-oxygen reaction period will arrive, and to judge the dephosphorization effect and slag formation effect. The non-quantitative subjective judgment logic that is difficult for computer automatic control system to identify and process is standardized and programmed, so that the computer model can be directly executed, thereby improving the controllability and stability of the converter smelting process and reducing the risk of human error.

[0009] Option 2, a preferred option of the basic option, in S1, the oxygen lance is a five-hole lance, the throat diameter of the oxygen lance nozzle is 37.5mm, the included angle of the oxygen lance nozzles is 12.5°, the Mach number of the oxygen lance nozzle is 2.04, and the oxygen lance pressure range is 0.8-0.9Mpa; this ensures that the oxygen jet from the oxygen lance has suitable impact force and coverage, providing a stable equipment foundation for subsequent lance position control and ensuring the consistency of the blowing effect.

[0010] Option 3, the preferred option of the basic scheme, involves an oxygen flow rate of 28,000 m³ / s in S1. 3 / h, oxygen supply pressure of 0.9MPa, and impact depth of 1041mm; in the early stage of converter smelting, the combination of high flow rate, high pressure and high gun position can ensure rapid and sufficient ignition, and avoid smelting delay or composition fluctuation caused by poor ignition.

[0011] Option 4, an optimal choice from the basic option, involves lowering the oxygen lance position to 1800mm in S1 and then adding slag material into the converter. The slag material consists of lime and magnesite, with the lime accounting for 80% of the total lime content and the magnesite accounting for 70% of the total magnesite content. Lowering the oxygen lance position and adding most of the slag material enables "early slag formation," creating alkaline slag in advance, laying the foundation for subsequent dephosphorization, while also slowing down the temperature rise and inhibiting the violent carbon-oxygen reaction.

[0012] Option 5, an optimal choice from the basic option, involves reducing the oxygen lance position by 50mm for every 10% of the total oxygen supply consumed in S2, until the oxygen lance is 1400mm above the molten iron surface. During the carbon-oxygen reaction, the oxygen lance position is reduced by 50mm for every 10% of the total oxygen supply consumed, until the oxygen lance position is 1400mm. This achieves a smooth transition in the oxygen lance position, avoiding splashing caused by sudden changes in lance position, while gradually enhancing the stirring of the molten pool to promote a balanced reaction.

[0013] Option 6, an optimal choice from the basic option, involves adding lime at 20% of the total lime content and magnesite at 10% of the total magnesite content in S2 when the oxygen supply reaches 15% of the total oxygen supply. When the oxygen supply reaches 24% and 33% of the total oxygen supply, 10% magnesite is added to the converter. This phased replenishment of the remaining slag maintains the slag basicity and fluidity, continuously promotes dephosphorization, and avoids a sudden drop in furnace temperature or deterioration of slag conditions caused by excessive addition of slag at one time.

[0014] Option 7, the preferred option of the basic option, involves adjusting the oxygen lance position in S3, setting the oxygen supply pressure to 0.5 MPa, and the oxygen flow rate to 16000 m³ / h. 3 / h, and when the oxygen supply remains at 600m 3 At that time, adjust the oxygen flow rate to 22000 m³ / h. 3 / h; Reducing the oxygen supply pressure and adjusting the oxygen flow rate during the dephosphorization control stage can promote the dephosphorization reaction while avoiding strong impacts that could cause slag to "dry out" or metal splashing. Detailed Implementation

[0015] The present invention will be further described in detail below through specific embodiments: Example A four-stage high and low lance operation method for controlling the state of the molten pool during model steelmaking includes the following steps: S1: High-Lance Smelting Ignition Stage: First, the desulfurized and slag-removed molten iron is loaded into the converter. Then, the operator remotely adjusts the oxygen lance height via the RSLogix5000 system, ensuring the oxygen lance is 2200mm above the molten iron surface. Oxygen blowing then begins to heat the molten iron in the converter, with an oxygen flow rate of 28000m³ / h. 3The oxygen supply is set at a rate of / h, an oxygen pressure of 0.9MPa, and an impact depth of 1041mm. When the oxygen supply from the oxygen lance reaches 5% of the total oxygen supply at a height of 2200mm from the molten iron, the oxygen lance position is lowered to 1800mm, and lime and magnesite are added to the converter. The amount of lime added is 80% of the total lime content, and the amount of magnesite added is 70% of the total magnesite content. The sum of the lime and magnesite added is 80% of the total slag content. S2: High-position carbon-oxygen reaction stage: When the oxygen supply from the oxygen lance reaches 12% of the total oxygen supply at a height of 1800mm above the molten iron, the operator adjusts the oxygen supply pressure to 0.85MPa and the oxygen flow rate to 26000m³ / h. 3 / h, and for every 10% of the total oxygen supply consumed, the oxygen lance position is lowered by 50mm until the oxygen lance is 1400mm above the molten iron surface; when the oxygen supply reaches 15% of the total oxygen supply, lime and magnesite are added to the converter in sequence, with the amount of lime added being 20% ​​of the total lime supply and the amount of magnesite added being 10% of the total magnesite supply; when the oxygen supply reaches 24% and 33% of the total oxygen supply respectively, 10% of magnesite is added to the converter respectively. S3: Low-position dephosphorization control stage: When the oxygen supply reaches 45% of the total oxygen supply, the operator adjusts the oxygen lance position to 1600mm from the liquid surface through the control system and continues blowing oxygen until the remaining oxygen supply is 1200mm. 3 At that time, the operator lowers the oxygen lance position to 1100mm via the control system, then reduces the oxygen supply pressure to 0.5MPa and the oxygen flow rate to 16000m³. 3 / h, when the remaining oxygen supply is 600m 3 At that time, adjust the oxygen flow rate to 22000 m³ / h. 3 / h; S4: "Low" lance position slag drying and splashing stage: when the oxygen supply is 300m³ remaining 3 At that time, lower the oxygen lance position to 1000mm and adjust the oxygen flow rate to 26000m³. 3 / h, while increasing the oxygen supply pressure to 0.9MPa until the oxygen injection ends.

[0016] In summary, this invention establishes a standardized four-stage oxygen lance position control method based on "high-high-low-low," which not only transforms traditional steelmaking operations that rely on workers' subjective experience into quantifiable instructions that can be recognized and executed by computer models, but also achieves precise control over the smelting start-up and ignition stages, carbon-oxygen reaction stages, dephosphorization control stages, and slag anti-drying and splashing later stages of converter smelting by systematically matching oxygen supply mode, lance height, pressure adjustment, and slag feeding timing. Ultimately, this results in a stable, splash-free converter smelting process with optimal dephosphorization efficiency, while also improving the fault tolerance of oxygen lance position operation, reducing operational complexity, and effectively promoting the transformation of steel production from experience-driven to model-driven.

[0017] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A four-stage high and low lance operation method for controlling the state of the molten pool during model steelmaking, characterized in that, Includes the following steps: S1: "High" lance position smelting and ignition stage: First, the molten iron after desulfurization and slag removal is loaded into the converter. Then, the operator remotely adjusts the height of the oxygen lance through the control system so that the oxygen lance is 2200mm away from the surface of the molten iron. Then, oxygen blowing is started to heat the molten iron in the converter. When the oxygen supply reaches 5% of the total oxygen supply, slag is added into the converter. S2: "High" Lance Position Carbon-Oxygen Reaction Stage: When the oxygen supply from the oxygen lance reaches 12% of the total oxygen supply at a height of 1800mm above the molten iron, the operator adjusts the oxygen supply pressure to 0.85MPa and the oxygen flow rate to 26000m³ / h. 3 / h, and when the oxygen supply reaches 15% of the total oxygen supply, the remaining slag is added into the converter; S3: "Low" Oxygen Lance Position Dephosphorization Control Stage: When the oxygen supply reaches 45% of the total oxygen supply, the operator adjusts the oxygen lance position to 1600mm from the liquid surface using the control system and continues blowing oxygen until the remaining oxygen supply is 1200mm. 3 At this time, the operator lowers the oxygen lance position to 1100mm via the control system; S4: "Low" lance position slag drying and splashing stage: when the oxygen supply is 300m³ remaining 3 At that time, lower the oxygen lance position to 1000mm and adjust the oxygen flow rate to 26000m³. 3 / h, while increasing the oxygen supply pressure to 0.9MPa until the oxygen injection ends.

2. The four-stage high and low lance position operation method for controlling the state of the molten pool during model steelmaking as described in claim 1, characterized in that, In S1, the oxygen lance is a five-hole lance, the throat diameter of the oxygen lance nozzle is 37.5 mm, the included angle of the oxygen lance nozzle is 12.5°, the Mach number of the oxygen lance nozzle is 2.04, and the oxygen lance pressure range is 0.8-0.9 MPa.

3. The four-stage high and low lance position operation method for controlling the state of the molten pool during model steelmaking as described in claim 1, characterized in that, In S1, the oxygen flow rate of the oxygen lance is 28000 m³ / h. 3 / h, oxygen supply pressure is 0.9MPa, and impact depth is 1041mm.

4. The four-stage high and low lance position operation method for controlling the state of the molten pool during model steelmaking as described in claim 1, characterized in that, In S1, after lowering the oxygen lance position to 1800mm, slag is added into the converter. The slag consists of lime and magnesite, with the amount of lime added being 80% of the total amount of lime and the amount of magnesite added being 70% of the total amount of magnesite.

5. The four-stage high and low lance position operation method for controlling the state of the molten pool during model steelmaking as described in claim 1, characterized in that, In S2, when the oxygen supply reaches 12% of the total oxygen supply, the oxygen lance position is lowered by 50mm for every 10% of the total oxygen supply consumed, until the oxygen lance is 1400mm above the molten iron surface.

6. The four-stage high and low lance position operation method for controlling the state of the molten pool during model steelmaking as described in claim 1, characterized in that, In S2, when the oxygen supply reaches 15% of the total oxygen supply, the amount of lime added is 20% of the total lime supply and the amount of magnesite added is 10% of the total magnesite supply; when the oxygen supply reaches 24% and 33% of the total oxygen supply respectively, 10% of magnesite is added to the converter respectively.

7. The four-stage high and low lance position operation method for controlling the state of the molten pool during model steelmaking according to claim 1, characterized in that, In S3, after adjusting the oxygen lance position, the oxygen supply pressure is adjusted to 0.5 MPa and the oxygen flow rate is adjusted to 16000 m³ / h. 3 / h, and when the oxygen supply remains at 600m 3 At that time, adjust the oxygen flow rate to 22000 m³ / h. 3 / h.