真空條件下鋼液脫氣過程的模擬研究

張國磊; 成國光; 代衛星; 張旭; 姜新巖

doi:10.13374/j.issn2095-9389.2021.01.01.002

真空條件下鋼液脫氣過程的模擬研究

doi: 10.13374/j.issn2095-9389.2021.01.01.002

1.
北京科技大學鋼鐵冶金新技術國家重點實驗室，北京100083
2.
西寧特殊鋼股份有限公司，西寧810005

基金項目: 國家自然科學基金資助項目（51674024, 51874034）

詳細信息

通訊作者:
E-mail: chengguoguang@metall.ustb.edu.cn

中圖分類號: TF135
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出版歷程
- 收稿日期: 2021-01-01
- 網絡出版日期: 2021-03-02
- 刊出日期: 2022-07-06

Simulation research on the degassing process of molten steel in a vacuum

1.
State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China
2.
Xining Special Steel Group, Co., Ltd., Xining 810005, China

More Information

Corresponding author: E-mail: chengguoguang@metall.ustb.edu.cn

摘要

摘要: 基于相似的動力學機理，利用水溶液中溶解氧的去除過程模擬了鋼液的真空脫氣行為. 在負壓25 kPa條件下發現，容器壁面或測氧探頭表面會析出大量細小氣泡，這一現象與以往脫氣數學模型假設的內部脫氣反應非常類似；為了驗證內部脫氣位點的存在，通過引入機械攪拌，對溶池表面和內部脫氣速率進行了分析計算. 實驗結果表明，在整個脫氣過程中溶池表面脫氣速率很低，內部脫氣位點析出的氣泡會極大地提高溶解氧的去除速率，尤其當真空壓力為25 kPa時，其脫氣速率約為自由表面的脫氣速率的10倍，但內部反應僅局限于脫氣的初始階段，即高溶解氧濃度范圍內. 另外，水溶液中溶解氧的去除為一級反應過程，其體積傳質系數（k · A · V^?1）為常數，因此可以利用溶解氧在水溶液中的去除過程模擬鋼液的真空脫氣行為. 為了描述真空壓力和吹氬流量對k · A · V^?1的影響，引入攪拌動能密度（ε）的概念，通過線性回歸得到了lg (k · A · V^?1)與lg ε之間的函數關系，并與以往的模擬研究進行了對比.
- 真空壓力 /
- 內部脫氣反應 /
- 氬氣流量 /
- 攪拌動能密度 /
- 體積傳質系數
Abstract: The vacuum degassing process plays an important role in the production of high cleanliness steel, so it is extremely urgent to determine the different reaction sites of liquid steel under reduced pressure and how to reflect the overall degassing efficiency through reasonable parameters. Based on a similar kinetic mechanism, this paper experimentally simulated the vacuum degassing process of molten steel using the release process of dissolved oxygen (DO) in water. Under a vacuum pressure condition, a large number of small bubbles were observed to precipitate from the vessel’s internal wall or the surface of the oxygen probe. This phenomenon corresponds well to the internal degassing reaction assumption made in previous degassing mathematical models. To verify the existence of internal degassing sites, mechanical stirring was introduced to analyze and calculate the degassing rate at the bath surface and internal site. Results showed that the degassing rate at the bath surface is very low throughout the whole process and the bubbles that precipitated from internal degassing sites greatly improve the DO removal rate. Especially at a pressure of 25 kPa, the degassing rate is about ten times that at the bath surface. It was also confirmed that the internal degassing reaction mainly occurs in the initial stage of degassing, particularly in the range of high DO concentration. Moreover, the removal of DO is a first-order reaction process, and its volumetric mass transfer coefficient k · A · V^?1 is constant. Therefore, the removal process of DO can be used to simulate the degassing behavior of molten steel. To describe the effect of vacuum pressure and argon flow rate on k · A · V^?1, the correlation between log (k · A · V^?1) and log ε was determined by introducing the concept of stirring power density ε. Finally, the correlation was compared with the results from previous simulation studies.
- vacuum pressure /
- internal degassing reaction /
- argon flow rate /
- stirring power density /
- volumetric mass transfer coefficient

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圖 1 實驗裝置示意圖

Figure 1. Schematic diagram of experimental apparatus

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圖 2 負壓下溶解氧隨時間的變化

Figure 2. Variation of dissolved oxygen concentration with time under vacuum pressure

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圖 3 不同壓力下溶氧儀探頭表面氣泡的析出過程. (a) P_v=101 kPa; (b) P_v=75 kPa; (c) P_v=50 kPa; (d) P_v=25 kPa

Figure 3. Bubble precipitation process from the surface of DO probe with different vacuum pressures: (a) P_v = 101 kPa; (b) P_v = 75 kPa; (c) P_v = 50 kPa; (d) P_v = 25 kPa

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圖 4 相同轉速下真空壓力對溶解氧的影響

Figure 4. Effect of vacuum pressure on dissolved oxygen concentration at a constant rotating speed

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圖 5 真空壓力對溶池表面和內部脫氣平均脫氣速率的影響

Figure 5. Effect of vacuum pressure on the average degassing rate at the bath surface and inner site

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圖 6 真空壓力對溶解氧濃度的影響

Figure 6. Effect of vacuum pressure on dissolved oxygen concentration

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圖 7 真空壓力下相對溶解氧濃度隨時間的變化

Figure 7. Variations of relative dissolved oxygen concentration with time under vacuum pressure

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圖 8 不同負壓下吹氬流量與體積傳質系數的函數關系

Figure 8. Relationship between argon flow rate and volumetric mass transfer coefficient under reduced pressure

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圖 9 攪拌動能密度對體積傳質系數的影響

Figure 9. Effect of stirring power density on the volumetric mass transfer coefficient

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圖 10 真空精煉脫氫過程中數學模型預測的體積傳質系數

Figure 10. Prediction of volumetric mass transfer coefficient using mathematical models in vacuum refining process

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