环形炉高温退火的水扩散模拟
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摘要
气氛含水量对取向硅钢高温退火的工艺质量具有显著影响,因此深入研究了环形炉高温退火中钢带层间含水量的变化规律。分析了钢带涂层中Mg(OH)_2分解速率与升温速率之间的关系,并通过试验证实了内罩内水蒸气分布的均匀性,建立了环形炉高温退火水扩散模型。结果表明,由于钢卷在退火过程中内部的升温速率不均,使得不同区域Mg(OH)_2的分解速率也不相同,钢卷的排水过程长达28 h。保护气氛的成分和钢带层间气隙的大小对排水速率影响显著,不同工况下,钢卷平均含水量可相差20%以上。此外,钢卷下端面与底板接触紧密,排水不畅,使用镂空底板可以大幅降低钢卷层间平均含水量。
Since the atmospheric moisture content has a significant influence on the quality control of the oriented silicon steel during the high temperature annealing process,the variation law of the moisture content in the gas entrapped in the gaps between the coil layers in the annular furnace was studied. Relationship between the heating rate and the deposition rate of Mg(OH)_2 in the coating of strip was analyzed,and the uniform distribution law of the vapour in the cover during the annealing process was proved by experiments. The model of the vapour diffusion in the annular furnace was built. The results showed that the deposition rate of Mg(OH)_2 differed at different parts of the coil because of the different heating rates,and it cost about 28 h to drain the water in the coil completely. The water content of the protective atmosphere and the width of gaps between coil layers have a significant impact on the drainage rate,and the difference of the average water content is more than 20% in some specific conditions. The vapour is entrapped at the bottom of coil due to the insufficient distance between coil and the plate. Furthermore,the application of the hollowed out plate can reduce the average water content between the coil layers significantly.
Since the atmospheric moisture content has a significant influence on the quality control of the oriented silicon steel during the high temperature annealing process,the variation law of the moisture content in the gas entrapped in the gaps between the coil layers in the annular furnace was studied. Relationship between the heating rate and the deposition rate of Mg(OH)_2 in the coating of strip was analyzed,and the uniform distribution law of the vapour in the cover during the annealing process was proved by experiments. The model of the vapour diffusion in the annular furnace was built. The results showed that the deposition rate of Mg(OH)_2 differed at different parts of the coil because of the different heating rates,and it cost about 28 h to drain the water in the coil completely. The water content of the protective atmosphere and the width of gaps between coil layers have a significant impact on the drainage rate,and the difference of the average water content is more than 20% in some specific conditions. The vapour is entrapped at the bottom of coil due to the insufficient distance between coil and the plate. Furthermore,the application of the hollowed out plate can reduce the average water content between the coil layers significantly.
引文
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[2] YANG F,HE C,MENG L,et al. Effect of annealing atmosphere on secondary recrystallization in thin-gauge grain-oriented silicon steel:Evolution of inhibitors[J]. Journal of Magnetism and Magnetic Materials,2017,439:403.
[3] Takamiya T,Kurosawa M,Komatsubara M. Effect of hydrogen content in the final annealing atmosphere on secondary recrystallization of grain-oriented Si steel[J]. Journal of Magnetism and Magnetic Materials,2003,254:334.
[4] LIU G,YANG P,MAO W. Effect of final annealing atmosphere on secondary recrystallization behavior in thin gauge medium temperature grain oriented silicon steel[J]. Acta Metallurgica Sinica,2015,52(1):25.
[5]胡志强,张文康,李慧峰,等.高温退火工艺对取向硅钢底层质量的影响[J].电工材料,2016(6):8.(HU Zhi-qiang,ZHANG Wen-kang,LIU Hui-feng,et al. Effects of high temperature annealing process on forsterrite quality in grain-oriented silicon steel[J]. Electrical Engineering Materials,2016(6):8.)
[6]司华青.低温取向硅钢底层质量的研究[D].沈阳:东北大学,2013.(SI Hua-qing. Study on Quality of Coating Layer of Low Temperature Grain-Oriented Silicon Steel[D]. Shenyang:Northeastern University,2013.)
[7] FANG S,HUANG S,JIN S,et al. Numerical simulation of the influence of the velocity angle of the hydrogen on the stream in the inner bell of the full-hydrogen annealing furnace[J]. Industrial Heating,2013,1:14.
[8] QI W D,SONG J C,REN G A. Analysis on gas flow field in bell-type annealing furnace by using FLUENT[J]. Applied Mechanics and Materials,2013,345:581.
[9] YUE L H,JIN D L,LU D Y,et al. The non-isothermal kinetic analysis of thermal decomposition of Mg(OH)2[J]. Acta PhysChim Sin,2005,21(7):752.
[10]谷伟,张虎,李增耀,等.混合气体在典型多孔介质内扩散过程的数值模拟[J].西安交通大学学报,2012,46(3):107.(GU Wei,ZHANG Hu,LI Zeng-yao,et al. Simulation on diffusion processes of multicomponent gas mixture in typical porous media[J]. Journal of Xi'an Jiaotong University,2012,46(3):107.)
[11] Taylor R,Krishna R. Multicomponent Mass Transfer[M]. America:John Wiley and Sons,1993.
[12] Kubaczka A. Prediction of Maxwell-Stefan diffusion coefficients in polymer-multicomponent fluid systems[J]. Journal of Membrane Science,2014,470:389.
[13]夏添,向志东,贺铸,等.环形炉温度场模拟及分析[J].钢铁,2018,53(9):91.(XIA Tian,XIANG Zhi-dong,HE Zhu,et al.Numerical simulation and analysis of temperature field for annular furnace[J]. Iron and Steel,2018,53(9):91.)