炉底电磁搅拌对电炉冶炼不锈钢工艺的影响

安装在电炉炉底下方的电磁搅拌器(ArcSave~)能使整个熔池的钢液产生有效的混合,从而加速熔炼过程中钢液温度和化学成分的均匀化。研究了电磁搅拌对瑞典Outokumpu不锈钢厂的90t电炉冶炼不锈钢工艺的影响。热测试结果显示,ArcSave能加速废钢和铬铁合金的熔化,精确控制出钢量;熔池的温度也更加均匀,出钢温度能得到准确的控制;稳定的电炉出钢质量和出钢温度的控制有利于后续AOD的顺利操作。通过对钢液的搅拌能减少熔池液面的过热度并提高熔池内的热传导,使得炉壁和炉盖的热损失减少,因此降低了耗电量和电极消耗量,总能耗能降低3%~4%。同时,搅拌也能强化钢-渣间的界面反应,降低渣中Cr_2O_3的含量,提高合金收得率和降低FeSi的消耗量。还能缩短冶炼周期,并且连续稳定的冶炼操作能提高电炉冶炼的产量约6%~8%。电磁搅拌技术是提高电炉冶炼不锈钢工艺水平的一种安全、可靠而有效的解决方案。     

双层半圆管盘式涡轮桨搅拌槽气液分散特性的数值模拟

采用基于气泡聚并和破碎机理的群体平衡(PBM-MUSIG)模型,对双层半圆管盘式涡轮桨搅拌槽内的气液分散特性进行了数值模拟;考察了不同通气量和操作转速下气液搅拌槽内流体流动,局部气含率和气泡尺寸的分布规律.模拟结果表明:通气工况下搅拌槽内的液相流场具有双循环流动形式;采用PBM-MUSIG模型预测的局部气含率分布与文献实验数据吻合较好;搅拌槽内气泡尺寸随转速增加而减小,随气量增加而增大;桨叶排出流区域内气泡尺寸较小,近壁区和循环区内气泡尺寸较大.     

数值模拟氧气底吹熔炼工艺参数优化

采用数值模拟方法，分别研究熔池深度、气体流量、氧枪倾角、氧枪直径等参数变化对熔池气含率、熔体平均速度和平均湍动能的影响.结果表明:当熔池深度为1.3~1.5 m时，熔池内部气液两相搅拌强烈，气含率存在较大值为17.5 %，熔池处于较好的运动状态；气含率、熔体平均速度和平均湍动能随气体流量的增加呈现先减小后增大趋势，选取适宜气体流量为0.6~0.7 kg/s；熔池气含率随氧枪倾角的逐渐增大先增大后减小，而熔体平均运动速度和平均湍动能呈现先减小后增大趋势，选取适宜氧枪倾角为20°~25°；氧枪直径为30~35 mm时，熔池气含率和平均湍动能处于较大值，约为13 %和0.8 m2/s2，熔池处于较好的运动状态.      

喷嘴结构对铁水脱硫气泡微细化的影响

针对铁水预处理镁蒸气脱硫的气泡微细化问题,本文通过水模型实验,研究了喷嘴结构对气泡在熔池中的分散、CO_2吸收速率和利用率以及均混时间的影响规律.结果表明:使用SSB-D桨,搅拌转速200 r/min,通气流量为1.0 m~3/h,偏心度0.4,浸入深度250 mm时,透气砖结构的喷嘴可以使熔池内的气泡分布"死区"减小,同时缩短了均混时间,提高了镁蒸气的容积传质系数和利用率.     

转炉聚合射流氧枪水模实验

以炼钢厂180t转炉为原型,进行顶底复吹转炉聚合射流氧枪吹炼的水力学模拟实验.实验通过降低枪位提高射流到达液面的速度,模拟聚合射流氧枪,在优化顶底复吹参数的基础上,研究聚合射流氧枪对转炉钢液搅拌效果的影响.实验结果表明:聚合射流氧枪可显著降低熔池均匀混合时间,其搅拌效果与顶底复吹相当.     

100 t顶底复吹转炉水力学模型研究

利用100t顶底复吹转炉进行水力学模型实验,研究纯底吹条件下不同底吹供气元件布置方案对熔池搅拌效果的影响,在此基础上,设计正交试验,分别研究复吹条件下底吹流量、顶吹流量和枪位对熔池混匀时间、冲击直径及冲击深度的影响.研究结果表明:底吹供气元件布置方案对熔池混匀效果影响很大;在顶底复吹条件下,顶吹流量对熔池混匀效果影响最大,且对于熔池冲击直径和冲击深度,顶吹流量和枪位起主要作用,底吹流量对其影响不大.     

侧吹AOD转炉的流体流动及气力穿透物理模拟研究

用物理模拟的方法研究了侧吹转炉中的主要流体流动模式。实验采用了粘度大致与钢液基本相同的水,在容器中的对称位置,用多普勒激光测速仪测定不同位置的水流速率。将三种不同熔池高度与四种不同气体流量组合进行了实验。结果显示,随着气体流量的加大,气股在风口平而及熔池液面处的穿透深度都增大了。同时,增大气体流量对气股在风口平面及熔池液面处穿透深度的影响比增大熔池高度所产半的影响大。最后,通过改变熔池高度和气体流量建立了系统的总体流动模式。     

贵溪冶炼厂贫化电炉二次扩容改造设计

贵溪冶炼厂二期工程闪速炉炉渣贫化电炉二次扩容改造,在原一期工程贫化电炉基础上,仅采用加长方式扩容的目的,新增设３５００ＫＶＡ变压器１台,改造后的贫化电炉总安装功能８００ＫＶＡ,为双变压器双供电系统６电极共熔池的新型炉渣贫化电炉。近一年来的安全运行实践表明,二次扩容改造设计方案是合理的,各项技术经济指标均达到设计要求,实现了“用最少的投资,最短的施工期限达到二期工程贫化电炉扩容的”目的。     

超高功率电炉炉底透气材料

我国现有电炉数量很大,特别是近年来有数家钢厂从国外引进了装备有底吹系统的超高功率电炉。其特点是:在电炉底部通过供气砖向炉内吹入惰性气体,使熔池内钢液形成循环流动,达到对钢液搅拌、加快冶金动力学反应的目的。采用这种设备可缩短冶炼时间、均匀钢水成分和温度、提...     

超高功率电炉炉底透气材料

我国现有电炉数量很大 ,特别是近年来有数家钢厂从国外引进了装备有底吹系统的超高功率电炉。其特点是 :在电炉底部通过供气砖向炉内吹入惰性气体 ,使熔池内钢液形成循环流动 ,达到对钢液搅拌、加快冶金动力学反应的目的。采用这种设备可缩短冶炼时间、均匀钢水成分和温度、提高钢材质量、降低生产成本。不过 ,该设备所需底吹供气元件一直依赖国外进口。　　为改变这种被动局面 ,钢铁研究总院与南京钢铁公司合作 ,成功地开发出适用于超高功率电炉炉底熔池搅拌用的新型供气元件 (透气砖 )。使用试验表明 :国产透气砖的侵蚀速率小、供气性能稳…     

300 t复吹转炉底吹系统优化模拟

 顶底复合吹炼转炉炼钢法是当下主流的炼钢方法,底部供气元件的种类、支数、排布方式和底吹供气强度直接影响着转炉熔池的混匀效果,合理的流场不仅可以降低生产成本,更能缩短冶炼周期,增加企业效益。基于冷态水模拟以及CFD数值模拟手段各自的研究特点,以某钢厂300 t转炉为原型,将不同底吹条件下熔池的混匀时间、死区以及弱流区体积作为评判依据,对300 t转炉的底枪排布方式、底吹供气模式(非均匀供气和均匀供气)以及底吹供气强度进行了系统研究,研究结果表明,当底枪排布位置由0.3D(D为炉底直径)到0.5D,底吹系统对炉壁处钢液的搅拌能力明显增强,但熔池内死区以及弱流区体积却会明显增加,使得整个熔池混匀时间增长;在对适宜底吹强度研究发现,当熔池底吹强度的临界值为0.28 m3/(t·min),此底吹强度下对熔池的搅拌效果最好;底吹系统对熔池的搅拌效果会随着供气模式的不同而改变,当底吹流量分配为2:1时,底吹系统对熔池的搅拌效果最佳,均匀供气模式(1:1)次之,而当分配比为3:1和4:1时,由于熔池的大流量侧供气强度相对较大,会极大影响底吹系统对熔池的搅拌效果。     

180 t转炉聚合射流流场的水力学模型的实验研究

采用几何相似比1∶10水模型对180 t顶底复吹转炉内射流与熔池相互作用进行模拟试验,研究了在最佳枪位(150 mm)时氧气流量(38~42 m³/h)对均混时间的影响以及最佳顶枪流量(39 m³/h)下聚合射流氧枪枪位(40~150 mm)对均混时间的影响。结果表明,聚合射流氧枪对熔池的搅拌效果完全能达到顶底复吹的搅拌效果,如能在转炉冶炼工艺中应用,可取消底吹系统,简化转炉设备,提高转炉炉龄。     

复吹转炉底吹非均匀供气对熔池搅拌混匀的影响

摘要：为了强化转炉熔池的搅拌,在200t复吹转炉1∶12的模型进行物理模拟试验,研究了底吹非均匀供气对转炉复吹和纯底吹熔池的搅拌混匀效果;采用数学模拟的方法计算了纯底吹条件下,转炉采用底吹非均匀供气时的熔池流体流动。研究结果表明,在所研究的不同的底吹非均匀供气方案中,与底吹均匀供气方案相比,线性底吹非均匀供气方案有利于改善转炉熔池搅拌效果,最佳的底吹非均匀供气方案的混匀时间比均匀供气降低了19%～25%。复吹时底吹非均匀供气的混匀时间降低程度要比纯底吹的非均匀供气大,即复吹条件下,底吹采用非均匀供气更有利于熔池搅拌混匀。采用线性底吹非均匀供气方案时,在熔池内形成了明显的大循环非对称流动,有利于整个熔池内的对流传质,从而缩短了混匀时间。     

Physical and mathematical models of gas‐liquid fluid dynamics in LD converters

Fluid dynamics of gas‐liquid interactions in a LD converter to refine steel was physically and mathematically simulated. Using a water model three cases of gas supply were considered, top blowing, bottom injection and combined process top blowing‐bottom injection. Mixing time in top blowing increases with bath height and the distance between the lance of the gaseous jet and the bath surface. The jet penetration was found to be dependent on the modified Froude number. The unstable and unsteady behaviour of the bath topography, as affected by the gaseous jet, was well simulated through a multiphase momentum transfer model. In top blowing, three zones of liquid splashing were found, penetration with low splash, heavy splash and dimpling with low splash intensity. These zones depend on the gas flow rate and the distance from the lance to the bath surface. During bottom injection mixing times decrease with the number of tuyères, increases of bath height and gas flow rate. In a combined process mixing time decreases considerably due to the recirculating flow formed by the action of the top jet and the submerged jets. When a submerged jet is located just below the top jet the mixing time does not decrease as compared with the separated processes either top blowing or bottom stirring.     

Research on molten flow simulation of 30t VOD ladle smelting stainless steel

30tVOD ladle smelting stainless steel was used as the process background, and the numerical and physical simulations were applied to investigate the flow and mixing characteristics of molten steel during the 30tVOD refining process. The cold experiment was employed to investigate the mixing behaviors of molten steel under the bottom and combined blowing systems. The flow features of molten steel were analyzed by numerical simulation with different blowing conditions. The results show that when the plug position of the ladle is located on 1/4R(R is the radius of ladle bottom), whether top- bottom blowing or bottom blowing, the molten steel is mixed well, and mixing time compared to the central position is reduced by 46% and 14% respectively. In addition, the comparison of flow field and turbulent kinetic energy of the molten steel show that when the bottom blowing position is 1/4R, the flow direction of the molten steel caused by the top blowing and the bottom blowing is better near the bath surface, and active volume ratio of molten steel is higher than that of other blowing positions. Current results were validated in industrial VOD furnace, which indicates that 1/4R is regarded as the optimum injection position for combined stirring.     

100 kg中频感应炉底吹氧搅拌的水模拟研究

采用几何相似比1:1的水模型对100 kg中频感应炉底吹氧的工艺参数(底吹流量0.2~0.56 m³/h,熔池高度120~330 mm)和流场进行模拟试验。结果表明,底吹熔池内形成的气相流速度在竖直方向上变化不明显,而在水平方向上存在较大梯度;随熔池高度和底吹流量的增加,气相流速度梯度变大,竖直气-液两相流变为倾斜向上运动;在熔池高度H小于240 mm、气体流量Q小于0.56 m³/h时,混匀时间分别随熔池高度和底吹流量的增加而减小,超过这一范围后混匀时间变化不明显。     

自旋转氧枪对熔池混匀时间影响的冷态模拟

摘要：针对传统氧枪对熔池搅拌能力有限,无法高效冶炼磷含量较高铁水的问题,设计一种新型自旋转氧枪,并建立了相应的冷态模拟系统,对比研究了自旋转氧枪与传统氧枪对熔池混匀时间的影响规律。结果表明,随着顶吹、底吹流量的提高以及枪位的下降,熔池混匀时间均缩短;自旋转氧枪对熔池的搅拌效果明显优于传统氧枪,熔池流场更加均匀;转速分别为0、3.14～5.23、7.33～9.42、11.51～13.61rad/s时,混匀时间分别降低12.0%、23.8%、24.4%、8.1%;能量密度的变化对混匀时间的影响小于传统氧枪。     

底吹喷枪结构对熔池搅拌效果的影响特性研究

针对目前底吹熔池熔炼过程中,如何改变喷枪结构起到强化搅拌目的的难题,采用数值模拟的方法建立了底吹熔池熔炼炉多相流非稳态数学模型,构建了多层栅栏结构的氧枪模型。计算结果表明,氧气底吹过程具有周期性,可分割成大气泡形成、气流柱形成和气流冲破熔池液面三个过程,并对有无栅栏喷枪结构在这三个过程下的相图、面平均湍动能、平均压力进行比对分析,结果表明多层栅栏枪口结构有助于强化熔池内部搅拌。     

Numerical Simulation of Fluid Flow in Bath during Combined Top and Bottom Blowing VOD Refining Process of Stainless Steel

The fluid flow in a bath in combined top and bottom blowing vacuum‐oxygen decarburization (VOD) refining process of stainless steel has numerically been simulated. The three‐dimensional mathematical model used is essentially based on that proposed in our previous work for the flow in combined side and top blowing argon‐oxygen decarburization (AOD) process, but considering the influence of reduced ambient pressure. Applying it to the flow in the bath of a 120 t VOD vessel under the refining conditions, the results present that the model can fairly well simulate and estimate the flow phenomena. The flow pattern of molten steel in the bath with the combined blowing is a composite result under the common action of the jets from a three‐hole Laval top lance and gas bottom blowing streams. The jets have a leading role on it; the molten steel in the whole bath is in vigorous stirring and circulatory motion during the blowing process. The streams do not alter the basic features of the gas agitation and liquid flow, but can evidently change the local flow pattern of the liquid and increase its turbulent kinetic energy to a certain extent. The flow field and turbulent kinetic energy distribution in the combined blowing with three tuyeres are more uniform than those in the blowing with double tuyeres. Increasing properly the tuyere eccentricities is of advantage for improving the velocity and turbulent kinetic energy distributions, the stirring and mixing result in the practical VOD refining process.     

Improvement of Impeller Blade Structure for Gas Injection Refining under Mechanical Sirring

The impeller blade structure for gas injection refining under mechanical stirring has been explored by water model experiments.A sloped swept-back blade impeller is proposed for the purpose.The central part of the impeller is disk-or plate-shaped,and the blades are fitted to the side of the disk or plate.In addition,a disk is put on the top side of the impeller blades.The impeller can strengthen the radial and downward flow between the blades and weaken the swirl flow in the zone above the impeller.These effects on flow phenomena are favorable for disintegration and wide dispersion of bubbles which are injected from a nozzle attached to the center of the underside of the impeller.In addition,the sloped swept-back impeller requires less power consumption.The impeller shaft should be placed away from the vessel center so as to disperse the injected bubbles widely in the bath under mechanical stirring even with unidirectional impeller rotation and without installing baffles.The number of gas holes in the nozzle and the direction of gas injection have a little effect on the bubble disintegration and dispersion in the bath.Highly efficient gas injection refining can be established under the conditions of proper impeller size,larger nozzle immersion depth,larger eccentricity and rotation speed of the impeller.The sloped swept-back blade impeller can decrease the power consumption and yet improve the bubble disintegration and wide dispersion in the bath.