5+1 oxygen lance system with high-efficiency molten bath stirring and deep dephosphorization function

Abstract

The present application relates to the technical field of steel metallurgy, and discloses a 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization function, which comprises an oxygen lance body, a nozzle body and a group of spray holes arranged on the nozzle body, the group of spray holes comprises one central main spray hole and five peripheral spray holes, the five peripheral spray holes are uniformly distributed on the same circle with the central axis of the nozzle as the center, and the five peripheral spray holes and the central main spray hole form a 5+1 layout; the axis of the central main spray hole coincides with the central axis of the oxygen lance body or forms an angle of 0-3 degrees; the angle between the axes of the five peripheral spray holes and the central axis of the oxygen lance body is 10-18 degrees; the oxygen lance system further comprises an independent gas path control system, and the central main spray hole and the peripheral spray holes are respectively connected with independent gas supply pipelines; the present application adopts a composite flow field reconstruction principle to improve the stirring rate, enhances slag-gold emulsification, improves the dephosphorization reaction rate, realizes the collaborative optimization of slagging and dephosphorization through the synergy of zoned slagging and temperature control.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, specifically to a 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions. Background Technology

[0002] Dephosphorization is a crucial metallurgical task in converter steelmaking. Phosphorus is largely a harmful element in steel, reducing its low-temperature toughness, weldability, and resistance to hydrogen-induced cracking. With the increasing demand for high-quality steel (such as automotive steel, pipeline steel, and marine engineering steel), the control requirements for phosphorus content at the converter's final stage are becoming increasingly stringent. Typically, the final phosphorus content is required to be ≤0.010%, and for some high-quality steels, it is even required to be ≤0.005%.

[0003] Traditional converter oxygen lances mostly use a 3-hole, 4-hole, or 5-hole evenly distributed nozzle structure, which mainly has the following technical problems:

[0004] First, the molten pool is not uniformly stirred. The oxygen jets of traditional porous oxygen lances are sprayed into the molten pool at the same angle (usually 12° to 15°), forming a stirring "dead zone" in the central area of ​​the molten pool. This results in asynchronous carbon-oxygen reactions in the upper and lower parts of the molten pool, as well as between the center and the edge, thus limiting the kinetics of the dephosphorization reaction.

[0005] Second, dephosphorization efficiency is limited. The dephosphorization reaction requires the slag to have high basicity, high oxidizing properties, and good fluidity, and to proceed fully at the slag-gold interface. Traditional oxygen lances struggle to create a sufficient slag-gold emulsion zone in the molten pool, resulting in an insufficient dephosphorization reaction interface and limiting the improvement of dephosphorization efficiency. The final phosphorus content of conventional processes is mostly between 0.012% and 0.018%, and it is difficult to consistently reach below 0.010%.

[0006] Third, the slag formation speed is slow. In the early stage of blowing, it is necessary to quickly form a primary slag with high basicity and high oxidizing properties, but the jet impact depth and impact area of ​​the traditional oxygen lance are difficult to achieve at the same time, which often requires a long slag formation time (usually 4 to 6 minutes), accounting for 20% to 30% of the blowing cycle and affecting production efficiency.

[0007] Fourth, it is difficult to adapt to new low-carbon smelting processes. In recent years, converter top-blown CO2 technology has been widely used due to its advantages of reducing carbon emissions and iron loss. However, the traditional oxygen lance nozzle structure is difficult to meet the differentiated requirements for jet shape and penetration depth when O2 and CO2 are mixed and blown.

[0008] Fifth, it is difficult to balance nozzle lifespan and mixing effect. To enhance the mixing effect, some technologies use methods such as increasing the nozzle inclination angle or increasing the number of nozzles, but this can easily lead to a decrease in nozzle cooling effect, mutual interference between jets between nozzles, and accelerated nozzle burn-out.

[0009] To address the above problems, this invention provides a 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions. Summary of the Invention

[0010] To address the problems existing in the prior art, the present invention aims to provide a 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions. Through the structural design and parameter optimization of 5 holes in the outer ring and 1 hole in the center, the molten pool flow field is reconstructed, the slag-gold interface reaction is enhanced, and the dephosphorization efficiency is significantly improved, while adapting to the requirements of low-carbon steelmaking processes.

[0011] The technical solution adopted by this invention to solve its technical problem is: a 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions, including an oxygen lance body, a nozzle body, and a group of nozzle holes arranged on the nozzle body. The nozzle hole group includes one central main nozzle and five peripheral nozzles. The five peripheral nozzles are evenly distributed on the same circumference with the central axis of the nozzle as the center, and the five peripheral nozzles and the central main nozzle form a 5+1 layout. The axis of the central main nozzle coincides with the central axis of the oxygen lance body or forms an angle of 0° to 3°. The angle between the axes of the five peripheral nozzles and the central axis of the oxygen lance body is 10° to 18°. The oxygen lance system also includes an independent gas path control system, and the central main nozzle and the peripheral nozzles are respectively connected to independent gas supply pipelines.

[0012] Specifically, at least two of the five peripheral nozzles have different tilt angle values. The tilt angle is the angle between the axis of the peripheral nozzle and the central axis of the oxygen lance body. Three of the peripheral nozzles have a small tilt angle of 10° to 13°, and two have a large tilt angle of 15° to 18°. The small tilt angle nozzles and the large tilt angle nozzles are distributed alternately.

[0013] Specifically, the design Mach number of the central main nozzle is 1.8 to 2.2, and the throat diameter of the central main nozzle is 20 to 40 mm; the design Mach number of the peripheral nozzles is 1.9 to 2.3, and the throat diameter of the peripheral nozzles is 25 to 45 mm; the ratio of the total throat area of ​​the peripheral nozzles to the throat area of ​​the central main nozzle is 3:1 to 5:1.

[0014] Specifically, the design Mach number of the central main nozzle is lower than the average Mach number of the peripheral nozzles, with the central main nozzle having a Mach number of 1.8 to 2.0 and the peripheral nozzles having a Mach number of 2.0 to 2.3.

[0015] Specifically, the nozzle body adopts a dual-channel independent cooling structure, which includes a central cooling channel and an outer cooling channel. The cooling water flow rate of the central cooling channel accounts for 25% to 35% of the total cooling water flow rate.

[0016] Specifically, the gas supply pipeline of the central main nozzle includes a main gas supply pipeline and an auxiliary gas supply pipeline. The main gas supply pipeline supplies O2, and the auxiliary gas supply pipeline supplies CO2 or a mixture of CO2 and O2. The independent supply of pure O2, pure CO2, or O2-CO2 mixture can be achieved by switching valves.

[0017] The gas supply pipeline of the outer nozzle supplies a mixture of O2 and CO2, with CO2 accounting for 5% to 25% of the volume.

[0018] Specifically, the oxygen lance system also includes an intelligent control module, which includes a data acquisition unit, a process parameter library, and a control execution unit. The intelligent control module dynamically adjusts the medium type, flow rate ratio, and oxygen lance position of the central main nozzle and peripheral nozzles based on online detection data of molten pool temperature, molten steel carbon content, and slag basicity.

[0019] A method for operating a 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions includes the following control steps for the blowing stage:

[0020] 1) Early stage of blowing: Pure CO2 is injected through the central main nozzle, and a mixture of O2 and CO2 is injected through the peripheral nozzles, with CO2 accounting for 5% to 15% of the volume;

[0021] 2) Mid-stage of blowing: Pure O2 is injected through the central main nozzle, and a mixture of O2 and CO2 is injected through the peripheral nozzles, with CO2 accounting for 10% to 20% of the volume.

[0022] 3) Later stage of blowing: The central main nozzle blows a mixture of O2 and CO2, with CO2 accounting for 40% to 60% of the volume, and the outer nozzle blows a mixture of O2 and CO2, with CO2 accounting for 15% to 25% of the volume.

[0023] Specifically, the feature is that the pure CO2 injection flow rate of the central main nozzle in the early stage of the blowing process accounts for 80% to 100% of the total flow rate of the central main nozzle.

[0024] Specifically, the oxygen lance position is controlled as follows during the blowing process: 1.8-2.2m in the early stage of blowing, 1.4-1.8m in the middle stage of blowing, and 1.7-2.0m in the later stage of blowing.

[0025] The present invention has the following beneficial effects:

[0026] This invention presents a 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions. It employs a composite flow field reconstruction principle. Traditional multi-hole oxygen lances use all nozzles at the same angle, resulting in independent impact pits formed by each jet in the molten pool, and a stirring "dead zone" in the central region. This invention, through the vertical or near-vertical jet from the central main nozzle, creates an upward recirculation zone in the center of the molten pool. This zone couples with the circulation zone formed by the peripheral nozzles, creating a composite flow field of "central upward movement - peripheral downward movement - radial diffusion." This enables full-area circulation stirring of the molten pool, both vertically and horizontally, improving stirring efficiency by 20%–30% compared to traditional 5-hole oxygen lances.

[0027] This invention presents a 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions. It employs the principle of slag-gold emulsification enhancement, where the dephosphorization reaction rate depends on the slag-gold interface area. By differentiating jet velocities and angles, this invention forms multi-scale, asymmetric impact spots on the molten pool surface, increasing the turbulence intensity at the slag-gold interface and promoting the mutual dispersion of slag droplets and molten metal droplets, forming a highly emulsified slag-gold mixture layer. Experiments show that using this oxygen lance system, the degree of slag-gold emulsification is increased by more than 40% compared to traditional oxygen lances, and the dephosphorization reaction rate constant is increased by 25%–35%.

[0028] This invention designs a 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions. It employs a synergistic principle of zoned slag formation and temperature control. In the early stages of blowing, CO2 is injected through the central main nozzle. Utilizing its endothermic reactions (CO2 + Fe = FeO + CO, ΔH = +158 kJ / mol; CO2 + C = 2CO, ΔH = +172.5 kJ / mol), it suppresses the rapid temperature rise in the central region of the molten pool, creating a temperature gradient of "low temperature at the center - high temperature at the periphery" within the molten pool. This temperature distribution is beneficial to the dephosphorization reaction: the low-temperature zone promotes phosphorus enrichment at the slag-gold interface, while the high-temperature zone ensures slag fluidity, achieving synergistic optimization of slag formation and dephosphorization.

[0029] This invention designs a 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions. Based on the jet-molten pool coupling dynamics principle, through a variable-angle layout and asymmetric nozzle distribution, the jets interfere and superimpose with each other before reaching the molten pool, forming a non-steady-state impact field. This induces chaotic convection in the molten pool, breaking the steady-state circulation mode formed by traditional oxygen lances. Chaotic convection significantly enhances the mixing efficiency of the molten pool, reducing the homogenization time of molten pool composition and temperature by 15%–20%. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be described clearly, completely, and in further detail below. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] A 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions includes an oxygen lance body, a nozzle body, and a nozzle group disposed on the nozzle body. The nozzle group consists of one central main nozzle and five peripheral nozzles, which are evenly distributed on the same circumference with the central axis of the nozzle as the center, forming a "5+1" layout with the central main nozzle.

[0032] 1. Nozzle structure parameters

[0033] 1.1 Central Main Spray Hole

[0034] The central main nozzle is located at the center of the nozzle body, and the axis of the central main nozzle coincides with or forms an angle of 0° to 3° with the central axis of the oxygen lance body.

[0035] The design Mach number of the central main nozzle is 1.8 to 2.2, the throat diameter D_c is 20 to 40 mm, and the ratio of the outlet diameter to the throat diameter is 1.2 to 1.6.

[0036] The gas flow rate of the central main nozzle accounts for 15% to 25% of the total gas supply.

[0037] 1.2 Peripheral spray nozzles

[0038] Five peripheral nozzles are evenly distributed, with an included angle of 72° between adjacent nozzles.

[0039] The angle between the axis of the outer nozzle and the central axis of the oxygen lance body (nozzle inclination angle) is 10° to 18°, and there are at least two different inclination angle values, forming a variable angle layout.

[0040] Of the five peripheral nozzles, three have a smaller tilt angle (10°–13°) and two have a larger tilt angle (15°–18°), and they are distributed alternately.

[0041] The design Mach number of the outer nozzle is 1.9 to 2.3, and the throat diameter D_p is 25 to 45 mm.

[0042] 1.3 Nozzle area ratio

[0043] The ratio of the total throat area of ​​the peripheral nozzles to the throat area of ​​the central main nozzle is 3:1 to 5:1.

[0044] Total gas supply flow rate is 30,000–80,000 Nm³ 3 / h.

[0045] 2. Media supply system

[0046] The oxygen lance system also includes an independent gas path control system. The central main nozzle and the peripheral nozzles are connected to independent gas supply pipelines, which can realize independent control of different media and flow rates.

[0047] 2.1 Central Main Jet Nozzle Air Supply Circuit

[0048] Main gas supply pipeline: O2 flow rate accounts for 60% to 85%.

[0049] Auxiliary gas supply pipeline: CO2 or a mixture of CO2 and O2, with a flow rate of 15% to 40%.

[0050] Independent supply of pure O2, pure CO2, or O2-CO2 mixture can be achieved by switching valves.

[0051] 2.2 External nozzle air supply circuit

[0052] Main gas supply line: a mixture of O2 and CO2, with CO2 accounting for 5% to 25% of the volume.

[0053] The mixing ratio can be dynamically adjusted according to the blowing stage.

[0054] 3. Control System

[0055] The oxygen lance system also includes an intelligent control module, which includes:

[0056] Data acquisition unit: Used to collect online detection data such as molten pool temperature, molten steel carbon content, slag basicity, and flue gas composition.

[0057] Process parameter library: Stores optimized process parameters for different steel grades and different blowing stages.

[0058] Control and execution unit: Based on the matching results of the collected data and the process parameter library, dynamically adjust the medium type, flow ratio and oxygen lance position of the central main nozzle and the peripheral nozzles.

[0059] Design Point 1: Differentiated Jet Velocity Design

[0060] The design Mach number of the central main nozzle is lower than the average Mach number of the peripheral nozzles, specifically:

[0061] Mach number of the central main nozzle: 1.8 to 2.0.

[0062] Mach number of peripheral nozzles: 2.0 to 2.3.

[0063] The differentiated design results in a relatively low jet velocity (approximately 450–500 m / s) in the central main nozzle, with a moderate penetration depth but a large impact area; while the jet velocity in the outer nozzles is higher (approximately 500–550 m / s), with a large penetration depth, together forming a composite flow field of "widening at the center and deep penetration at the periphery".

[0064] Design Point Two: Optimization of Nozzle Cooling Structure

[0065] The nozzle body adopts a dual-channel independent cooling structure:

[0066] Central cooling channel: Specifically designed to provide enhanced cooling for the central main nozzle, with a cooling water flow rate accounting for 25% to 35% of the total cooling water volume.

[0067] External cooling channel: Provides cooling for the external nozzles, with a cooling water flow rate of 65% to 75%.

[0068] Cooling water inlet temperature ≤35℃, outlet water temperature ≤50℃, nozzle surface temperature ≤450℃.

[0069] Design Point 3: Enhanced CO2 Injection Mode at the Central Main Nozzle

[0070] During the early stage of blowing (0-4 minutes) and the later stage of blowing (when carbon content ≤0.1%), the central main nozzle is switched to a pure CO2 or high CO2 ratio (80%-100%) blowing mode:

[0071] Early stage mode: Pure CO2 is injected through the central main nozzle. The endothermic reaction between CO2 and molten iron is used to suppress the rapid rise of the initial molten pool temperature and promote low-temperature dephosphorization.

[0072] Later mode: The central main nozzle injects a mixture of gas with a volume ratio of 40% to 60% CO2, which utilizes the weak oxidizing properties of CO2 to reduce the degree of over-oxidation of molten steel and at the same time strengthens the stirring of the molten pool.

[0073] Design Point 4: Optimization of the Variable Angle Layout of the Peripheral Spray Holes

[0074] The five peripheral nozzles are arranged in a mixed layout with three different tilt angles:

[0075] Type 1 nozzles (2): Inclined at 10° to 12°, mainly acting on the shallow layer of the molten pool to expand the impact area.

[0076] The second type of nozzle (2): with an inclination angle of 13° to 15°, mainly acts on the middle layer of the molten pool to form the main stirring zone.

[0077] The third type of nozzle (1): with an inclination angle of 16° to 18°, mainly acts on the deep layer of the molten pool, penetrating to the bottom of the molten pool.

[0078] The three types of nozzles are alternately distributed in the order of "small-medium-small-large-medium" to form an asymmetric jet layout, avoid the formation of standing wave effect, and enhance the chaotic stirring effect of the molten pool.

[0079] The position control of the oxygen lance body during the blowing process is as follows: 1.8-2.2m in the early stage of blowing, 1.4-1.8m in the middle stage of blowing, and 1.7-2.0m in the later stage of blowing.

[0080] This invention relates to the application of deep dephosphorization steelmaking in the iron and steel metallurgy industry. It is suitable for 100-350 ton top-and-bottom combined blowing converters, and the final phosphorus content can be controlled at 0.006%-0.009%.

[0081] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0082] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions, characterized in that, The system includes an oxygen lance body, a nozzle body, and a nozzle group disposed on the nozzle body. The nozzle group includes one central main nozzle and five peripheral nozzles. The five peripheral nozzles are evenly distributed on the same circumference with the central axis of the nozzle as the center, forming a 5+1 layout with the central main nozzle. The axis of the central main nozzle coincides with or forms an angle of 0° to 3° with the central axis of the oxygen lance body. The angle between the axes of the five peripheral nozzles and the central axis of the oxygen lance body is 10° to 18°. The oxygen lance system also includes an independent gas path control system, with the central main nozzle and the peripheral nozzles connected to independent gas supply pipelines.

2. The 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions according to claim 1, characterized in that, Of the five peripheral nozzles, at least two have different tilt angles. The tilt angle is the angle between the axis of the peripheral nozzle and the central axis of the oxygen lance body. Three of the peripheral nozzles have a small tilt angle of 10° to 13°, and two have a large tilt angle of 15° to 18°. The small tilt angle nozzles and the large tilt angle nozzles are distributed alternately.

3. The 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions according to claim 1, characterized in that, The design Mach number of the central main nozzle is 1.8 to 2.2, and the throat diameter of the central main nozzle is 20 to 40 mm; the design Mach number of the peripheral nozzles is 1.9 to 2.3, and the throat diameter of the peripheral nozzles is 25 to 45 mm; the ratio of the total throat area of ​​the peripheral nozzles to the throat area of ​​the central main nozzle is 3:1 to 5:

1.

4. The 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions according to claim 3, characterized in that, The design Mach number of the central main nozzle is lower than the average Mach number of the peripheral nozzles. The Mach number of the central main nozzle is 1.8 to 2.0, and the Mach number of the peripheral nozzles is 2.0 to 2.

3.

5. The 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions according to claim 1, characterized in that, The nozzle body adopts a dual-channel independent cooling structure, which includes a central cooling channel and an outer cooling channel. The cooling water flow rate of the central cooling channel accounts for 25% to 35% of the total cooling water flow rate.

6. The 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions according to claim 1, characterized in that, The gas supply pipeline of the central main nozzle includes a main gas supply pipeline and an auxiliary gas supply pipeline. The main gas supply pipeline supplies O2, and the auxiliary gas supply pipeline supplies CO2 or a mixture of CO2 and O2. The independent supply of pure O2, pure CO2, or O2-CO2 mixture can be achieved by switching valves. The gas supply pipeline of the outer nozzle supplies a mixture of O2 and CO2, with CO2 accounting for 5% to 25% of the volume.

7. The 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions according to claim 1, characterized in that, The oxygen lance system also includes an intelligent control module, which includes a data acquisition unit, a process parameter library, and a control execution unit. The intelligent control module dynamically adjusts the medium type, flow rate ratio, and oxygen lance position of the central main nozzle and peripheral nozzles based on online detection data of molten pool temperature, molten steel carbon content, and slag basicity.

8. The operating method of the 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions according to any one of claims 1-7, characterized in that, The following are the control steps for the blowing stage: 1) Early stage of blowing: Pure CO2 is injected through the central main nozzle, and a mixture of O2 and CO2 is injected through the peripheral nozzles, with CO2 accounting for 5% to 15% of the volume; 2) Mid-stage of blowing: Pure O2 is injected through the central main nozzle, and a mixture of O2 and CO2 is injected through the peripheral nozzles, with CO2 accounting for 10% to 20% of the volume. 3) Later stage of blowing: The central main nozzle blows a mixture of O2 and CO2, with CO2 accounting for 40% to 60% of the volume, and the outer nozzle blows a mixture of O2 and CO2, with CO2 accounting for 15% to 25% of the volume.

9. The operating method of the 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions according to claim 8, characterized in that, The pure CO2 injection flow rate of the central main nozzle during the early stage of blowing accounts for 80% to 100% of the total flow rate of the central main nozzle.

10. The operating method of the 5+1 converter oxygen lance system with efficient molten pool stirring and deep dephosphorization functions according to claim 8, characterized in that, The position control of the oxygen lance body during the blowing process is as follows: 1.8-2.2m in the early stage of blowing, 1.4-1.8m in the middle stage of blowing, and 1.7-2.0m in the later stage of blowing.