不同钢包底吹氩模式对钢液精炼效果的影响

以180 t双孔底吹氩钢包为研究对象,对6种钢包底吹氩模式进行数值模拟,并结合现场试验与当前采用的吹氩模式进行对比。研究发现：（1）钢液的混匀时间随吹氩量的增加而减少,吹氩量一定时,差流量吹氩模式对钢液的搅拌强于等流量吹氩模式。（2）不同的钢包底吹氩模式,渣眼形成的位置不同,渣眼面积也不同。总流量一定时,差流量吹氩模式钢液面最大流速大于等流量吹氩模式,易发生钢液卷渣。（3）差流量吹氩模式渣线处渣层厚度的波动大于等流量吹氩模式,且流量差值越大,波动越剧烈。（4）差流量吹氩模式通过“强-弱”流股的配合,进一步强化了钢包底吹氩的钢液精炼效果。工业试验表明,采取等流量吹氩模式（500 L/min—500 L/min）,钢中的较大夹杂物的数目明显多于差流量吹氩模式（400 L/min—600 L/min）。     

100 t底吹氩钢包插入浸渍管对钢液流场影响的数值模拟

以100t单孔底吹氩钢包为原型,应用三维连续性方程、动量N-S方程及湍流κ-ε双方程模拟了底吹氩过程中钢包内的钢液流动状态。利用Mixture多相流模型对单孔吹氩（0~700 L/min）过程进行数值模拟,对比分析插入直径691.05 mm,深650 mmn浸渍管前后钢包内的流动状态和钢液表面的卷渣。结果表明,无浸渍管时,临界卷渣吹气量为102 L/min,插入浸渍管后,临界卷渣吹气量增大到217 L/min。插入浸渍圆筒可以在增加吹氩量的条件下提高钢液搅拌效果,加速钢液混匀。     

氩气流量对100 t 底吹钢包内渣眼形成影响的数值模拟

通过建立的氩气底吹钢包三维非稳态三相流动数学模型以及Fluent软件和Simple算法研究了钢包精炼底吹氩过程保护渣的流动特性,并分析了喷嘴直径0.1 m时200~3500 L/min喷气量对渣眼尺寸、渣层运行的影响。结果表明,随喷气量增大渣眼增大,当氩气流量为400~2000 L/min时渣眼大小和钢包内流场分布较合理,有利于精炼;随渣层厚度增加,渣眼减小,但渣厚超过200 mm时,渣层厚度的增加对渣眼大小影响不显著。     

100t钢包吹氩工艺优化数值模拟研究

通过数值模拟,研究了100 t钢包在LF精炼过程中底吹氩气流量对钢包内钢液流动特性、"渣眼"面积及活跃区比例的影响.结果表明,在一定范围内,增大吹氩量有利于增大"渣眼"面积,强化钢水运动,缩小"死区"体积比例,有利于脱硫反应的进行.但当吹氩量超过临界值时,"死区"体积比例缩小幅度降低.100 t钢包最佳吹氩量为300 L/min.     

120 t钢包底吹氩气物理模拟

为了优化国内某钢厂钢包的底吹位置和气体流量等工艺参数,更好地提高钢水洁净度,对120 t钢包建立1∶3水模型,模拟研究了底吹位置和气体流量对钢液混匀时间和钢渣覆盖情况的影响。结果表明,底吹位置不同时,混匀时间存在明显差异;随着气体流量增大,钢包混匀时间整体呈下降趋势,但减小幅度越来越小,吹气流量有最佳值;底吹位置为0.4R-0.6R,气体流量为500~700 L/min时,混匀时间由大到小的双孔角度为双孔135°＞双孔90°≥双孔120°;相同吹气量条件下单孔透气砖布置比双孔透气砖引起的钢渣卷入深度更大,深度差距基本为20~70 mm,而引起的渣眼面积大小则为双孔大于单孔。综合考虑混匀时间和钢渣覆盖情况,最优的透气砖布置和工况参数为双孔120°-0.4R-0.6R、气体流量500~600 L/min。     

差流量吹氩模式对150 t钢包混匀与顶渣行为的影响

 针对钢包传统的双孔等流量底吹氩模式在流量较大时造成的流股相互碰撞、搅拌能耗散大、钢包卷渣和钢水二次氧化倾向大的问题,提出一种双孔差流量搅拌模式,并以150 t工业钢包为原型,采用1∶3物理模型研究了两个吹氩孔分布、吹氩流量和渣层厚度对新底吹模式下钢水混匀时间与顶部渣眼面积的影响。结果表明,与传统等流量吹氩模式相比,双孔差流量搅拌钢包混匀时间和渣眼面积普遍有所减小。其中,两个底吹透气砖在包底0.6R(钢包底部半径)处、夹角为180°时,可获得较短的混匀时间和较小的渣眼,且两个渣眼出现在钢包液面两侧,避免了常见的渣层偏聚不均匀现象。研究结果为工业实践中采用新型双孔差流量搅拌模式改善钢包冶金效果、更好地抑制钢水二次氧化提供了依据。     

底吹氩钢包内渣-金反应及脱硫行为的数值模拟

为了提高底吹氩钢包脱硫效率,建立了CFD-SRM耦合模型描述底吹氩钢包内渣-金反应及脱硫行为,考虑了钢包内底吹引起的湍流流动和渣圈中氧气吸收及氧化反应等因素对渣-金反应动力学的影响规律,通过80 t钢包热态试验验证了数学模型,并揭示了不同吹炼制度对底吹氩钢包脱硫效率的影响规律,得出合理的优化参数。结果表明,气液两相流对组分质量传输速率和脱硫效率有着重要影响,CFD-SRM耦合模型可以准确预测底吹钢包内的渣-金反应和脱硫行为,钢包双孔喷吹的脱硫效果对单孔中心和偏心布置更优。随着渣-金高度比的增加,脱硫效率增加,当渣钢高度比超过0.04时,脱硫效率变化很小;随着底吹流量的增加,脱硫率先增大后减小,但当底吹流量超过300 L/min(标准态)时,钢液脱硫率开始降低。     

底吹氩VD钢包炉流场优化的数值模拟研究

以某钢厂150 t VD钢包炉为研究对象,采用商业软件Ansys-Fluent,建立钢包底吹氩气模型,结合正交设计方法,模拟了不同钢液量,两个吹氩口不同吹氩量工艺条件下钢包内流场和流速变化,同时考虑了静置10 min后钢包炉内钢液流动情况。所有试验均监测钢包下部同一位置的速度大小,通过正交设计方法选择最优的生产方案。研究结果表明:钢包内钢液量和底吹氩气量在小范围内变动对钢包内钢液流场和流速影响不大,且钢液量和氩气口吹氩量对静置10 min后钢液内流场流速的影响可以忽略不计。吹氩量过大会导致渣眼开度较大引起卷渣和吸气现象,吹气量过小钢液流速较低则导致形成稳定循环流场所需时间较长。最终通过对比分析得出在钢液高度选用3 590 mm,1#和2#氩气口流量均采用0.9 m~3/h时钢包炉内综合流动效果较好,减少了钢水受污染程度,提高了生产效率。     

使用圆孔透气塞的钢包内流场及其渣眼行为研究

由于圆孔取代矩形狭缝后,可以有效地缓解透气塞狭缝孔周应力集中和延长其使用寿命,因而研究其精炼过程显得十分必要。文中采用离散相模型与VOF模型对钢包吹氩过程进行了研究,对比分析了不同流量下使用圆孔狭缝式透气塞的钢包内的流场和渣眼面积,并采用水模试验方法验证了数值模拟。结果表明:底吹气体流量对钢包的流场特征影响不大,当流量高于3.76 L/min时,流量的增大对钢液的流速影响不大,当底吹流量低于3.76 L/min时,流量增大,钢液流速增大;而且水模试验中的渣眼面积与数值模拟得到的渣眼面积吻合较好。     

钢包出钢阶段吹氩搅拌去除夹杂物的模拟研究

针对钢包出钢过程建立了钢液-渣相-气相-氩气泡-夹杂物的五相数学模型，探索了钢包出钢过程中吹氩搅拌去除夹杂物的可行性，以及吹氩流量对流场、渣眼、夹杂物去除效率的影响规律。结果表明：吹氩搅拌可强化浇钢过程中钢液的流动行为，显著提升夹杂物的去除率。相较于未采用吹氩搅拌，当吹氩流量为100 L/min、出钢750 s时，夹杂物的去除率由80.74%提升至96.69%，流入中间包夹杂物的数量减少67.4%；随吹氩流量增加，渣眼尺寸增大，夹杂物去除速率增加，但去除效率变化不大，推荐吹氩流量为100 L/min。     

透气砖布置和吹氩流量对钢包内钢液流动行为的影响

针对攀钢200t钢包,采用物理模拟与数值模拟相结合的方式,研究了透气砖布置方式和吹氩流量对钢液流动行为的影响规律。结果表明,当两透气砖呈120°布置在距包底中心0.62R(R为包底半径)处时,钢液的平均流速和平均湍动能大,"死区"范围小,混匀时间短,是合理的透气砖布置方式,其临界吹氩流量为27m3/h;与单透气砖相比,双透气砖喷吹的能量利用率高,"死区"范围小,单透气砖的吹氩流量需控制到45m3/h才能达到与双透气砖吹氩流量为27m3/h时相同的搅拌效果。实践证明,研究得到的透气砖布置方式和吹氩流量能保证熔池的搅拌效果,使转炉钢水经吹氩处理后,钢包不同位置温差小于10℃,Δw[C],Δw[Si],Δw[Mn]小于0.03%;在一定的软吹氩流量条件下,吹氩时间大于等于8min,可以使钢中wT[O]小于25×10-6。研究表明,用离散相模型对钢包底吹氩过程进行数值模拟,可以得到与物理模拟试验和生产实践较为吻合的结果。     

Mathematical Modeling on Erosion Characteristics of Refining Ladle Lining with Application of Purging Plug

According to parameters of the refining ladle with argon bottom blowing, the mathematical model describing the erosion behavior of ladle lining materials was established, the flow process of molten steel and thermal transmission of ladle lining were coupled, and the erosion of ladle lining in the condition of blowing argon at the bottom was researched. It has been found that either single or double blowing is applied, the larger erosion rates are mainly distributed in the slag line and the area of ladle lining near purging plugs, and the erosion is accelerated with the gas flow rate increasing, so the areas with higher erosion rates of the lining should be enhanced to avoid early partial damage. The erosion rate of ladle lining with double blowing is larger and the distribution of erosion is obviously different as the gas flow rate is increasing; serious erosion areas are in the slag line region and the higher erosion areas are concentrated on the slag lining and extended toroidally. And, as the distance between the purging plug and the lining of ladle is shortened, the partial erosion is easy to deteriorate and the refractories in the area with higher erosion rate need specialized selection and design. Meanwhile, the purging plug should be located away from the lining wall under the condition of good blowing effect in order to avoid increasing of the partial erosion and shortening of the lining service life.     

钢包底吹氩卷渣临界条件的水模型研究

以钢厂70t钢包为原型,建立模型与原型尺寸比为1:2.75的水模型。通过水模型实验对钢包临界卷渣吹氩量进行测量,得到临界卷渣气量是450 L/min。实验测量不同吹气量下钢包液面水平流速,分析水平流速与钢包卷渣的关系,得到钢包临界卷渣的液面流速为0.652m/s、韦伯准数为6.967。讨论了采用临界卷渣韦伯准数计算临界卷渣液面流速,通过测量达到临界卷渣液面流速时的吹氩量,来确定临界卷渣吹氩量的方法。     

110t不锈钢钢包炉底吹氩水模拟

依据相似原理建立钢包的物理模拟体系,采用水模型对110t LF钢包底吹氩过程进行研究,分析了吹气量、吹氩位置、钢包覆盖渣和钢包液面高度对钢包混匀的影响,并进行了相应的试验验证。研究结果表明：水模型试验结果和大工业应用具有较好的一致性,验证了水模型的可行性;钢包液面高度越高,混匀时间越长;吹气量越大,混匀时间越短;相同的液面高度和吹气量下,底吹氩最佳位置为0.33r 附近;钢包覆盖渣较黏时会使钢液流动显著减慢,增大吹气量容易产生卷渣现象。     

Numerical Simulation of Fluid Flow and Interfacial Behavior in Three‐phase Argon‐Stirred Ladles with One Plug and Dual Plugs

A numerical investigation is performed to describe the quasi‐steady fluid flow and interfacial behavior in a three‐phase argon gas‐stirred ladle with off‐centered bottom Ar injection through a plug and two plugs placed in 180° and 90°configurations, respectively. The flow of the fluid phase is solved in an Eulerian frame of reference together with the motion of every individually injected Ar bubble, tracked in its own Lagrangian frame. Volume of fluid (VOF) model is used to track any interface between two or more immiscible phases, which include slag/metal, slag/gas and metal/gas. The characteristics of fluid flow in a gas‐stirred ladle with one plug or two plugs configuration are described when the slag layer and the top gas are presented. The slag layer deformation and slag open‐eye formation at different Ar gas flow rates for three types of plug arrangements are given. The comparison of the mixing time, the deformation of slag layer and the behavior of slag/steel interface between one‐plug and two‐plug system is made. Several implications for ladle operational issues during a gas‐stirred ladle refining cycle are discussed. It is found that the proper selection of Ar gas flow rate and plug arrangements during a ladle refining cycle is required for different refining purposes considering the mixing and metallurgical reaction in a three‐phase ladle system.     

A novel dual plugs gas blowing mode for efficient ladle metallurgy

A novel gas blowing mode with different flowrates for two plugs of metallurgical ladle is explored and studied through a sophisticated water model. The results show that this mode can efficiently decrease the mixing time and the total area of the slag eye for most cases, as compared with the conventional mode with same flowrates for two plugs. Generally, a relatively close angle between the porous plugs and a small radial position are beneficial to a decrease in the mixing time of bath, while a relatively far plug radial position leads to a smaller slag eye. In addition, tracers fed from the middle of the dual plugs are proven to be very beneficial to the mixing of the ladle. The slag layer will prolong the mixing time due to its consumption on the stirring energy compared with the situation without slag.     

150 t钢包底吹氩卷渣行为的物理模拟

针对钢厂150 t双孔底吹氩钢包,根据相似原理建立几何比例为1:5的水力学模型,得出对应实际氩流量260~600 L/min时原型钢包及优化后钢包的液面裸露面积及渣钢卷混情况的变化规律和临界卷渣气量。研究结果表明,原型方案下两透气砖分别位于距钢包中心0.64 R和0.76 R处,两孔成90°(0.64 R+0.76 R,90°),临界卷渣气量为550 L/min;对于两个优化方案,双孔分别位于1/3 R和0.64 R,两孔成180°(1/3 R+0.64 R,180°)以及双孔位于0.5 R圆周上,两孔成135°(0.5 R+0.5 R,135°),临界卷渣气量分别为550 L/min与600 L/min。