Secondary cooling technology for high-efficiency continuous billet-casting

The mathematical model of high-efficiency continuous billet casting was developed, incorporating the effective spraying water coefficient and the effective specific spraying water flowrate of secondary cooling. To realize uniform cooling in secondary cooling zones, the spraying cooling structure and the arrangement of nozzles were redesigned and optimized, and an additional spraying cooling zone was used. A new secondary cooling model of spraying water was built. It was found that the required spraying water flowrate of a cooling zone was related with the casting speed, the casting temperature, the compositions of liquid steel and the cooling water temperature of secondary cooling. The operation of the reformed caster proved that the spraying cooling structure and the new secondary cooling model were suitable, and the casting speed was greatly enhanced. The highest casting speed was （3.8 to 4.0） m/min for billet with a section of 150× 150 mm^2. The quality And the outout of the billet were imoroved, andthe economical benefit was heightened.

Effect of droplet characteristics on liquid-phase distribution in spray zone of internal mixing air-mist nozzle

In continuous casting production,droplet characteristics are important parameters for evaluating the nozzle atomization quality,and have a significant impact on the secondary cooling effect and the slab quality.In order to study the behavior of atomized droplets after reaching the slab surface and to optimize the spray cooling effect,the influence of droplet diameter and droplet velocity on the migration behavior of droplets in the secondary cooling zone was analyzed by FLUENT software.Results show that the droplets in the spray zone and on the slab surface are mainly concentrated in the center,thus,the liquid volume fraction in the center is higher than that of either side.As the droplet diameter increases,the region of high liquid volume fraction on the slab surface becomes wider,and the liquid phase distribution in the slab width direction becomes uneven.Although increasing the droplet velocity at the nozzle exit has little effect on droplet diffusion in the spray zone,the distribution becomes more uneven due to more liquid reaches the slab surface per unit time.A prediction formula of the maximum water flow rate on the slab surface for specific droplet characteristics was proposed based on dimensionless analysis and validated by simulated data.A nozzle spacing of 210 mm was recommended under the working conditions in this study,which ensures effective coverage of the spray water over the slab surface and enhances the distribution uniformity of water flow rate in the transverse direction.

Calculation of Solidification Process of Continuous Cast Bar

In this paper,it presents the results of calculation of solidification process of copper continuous cast bar by cross section size 120 mm × 70 mm with application of Pro Cast 2010 software. The estimation of mould design effect on solidification process of continuos copper cast bar is completed at various speeds of casting.Profiles of liquid metal cavities and temperature allocations in the cast bar at various casting speeds are defined.The analysis of received liquid metal cavity profiles shows that a new mold construction allows significantly decrease of the length of the liquid metal cavity during continuous copper casting at HAZELETTcasting machine and the increase of maximum casting speed from 10 to 11 m / min. Adequacy of the results of copper continuous cast bar solidification process calculation is confirmed by the experimental data.

某钢厂炼钢连铸循环水处理站工艺设计

炼钢连铸循环水处理站是保障炼钢正常生产的重要公辅设施,该循环水处理站有炼钢除盐水循环水系统、连铸除盐水循环水系统、喷淋除盐水循环水系统、炼钢净循环水系统、连铸净循环水系统、煤气冷却器浊循环水系统、连铸浊循环水系统这七大系统。以某钢厂炼钢连铸循环水处理站为例,对其具体的设计方法及相关技术要点进行探讨。

25MnSiV矩形连铸坯疏松缩孔模拟研究

建立了25MnSiV矩形连铸坯凝固组织数学模型,研究了拉速、过热度、二冷区给水量对连铸坯疏松缩孔的影响规律。结果表明,提高拉速和过热度均会增加铸坯疏松缩孔比例,而增加二冷区给水量能降低铸坯疏松缩孔比例,最佳工艺参数分别为拉速1.0 m/min、过热度20℃、二冷区给水量为最大给水量的60%。

Dynamic Water Modeling and Application of Billet Continuous Casting

The continuous casting process is used for solidifying molten steel into semi-finished steel.The technology of secondary cooling is extremely important for output of the casting machine and billet quality.A dynamic water model was introduced,including solidification model in the secondary cooling,feedforward control strategy based on continuous temperature measurement in tundish,and feedback control strategy based on surface temperature measurement.The mathematical model of solidification process was developed according to the principle of solidification,and the solidification model was validated by measuring billet shell thickness through shooting nail and sulfur print.Primary water distribution was calculated by the solidification model according to procedure parameters,and it was adjusted by the other two control strategies online.The model was applied on some caster and billet quality was obviously improved,indicating that the dynamic water model is better than conventional ones.

双水内冷连铸辊道系统故障关联规则诊断技术

双水内冷连铸辊道系统主要由循环水站/水泵、托梁架、辊道等部件组成,其中任意部件产生故障都会影响连铸生产过程,为保障连铸生产效率与质量,研究了双水内冷连铸辊道系统故障关联规则诊断技术。构建基于关联规则的故障诊断模型,采集双水内冷连铸辊道系统运行过程中各部件的运行故障数据,采用优化后的Apriori算法挖掘故障数据内的频繁项集,挖掘故障数据间的关联规则,针对故障类型与故障原因的是否已知,生成关联规则构建相关故障规则库,基于其中的规则诊断双水内冷连铸辊道系统故障,并根据诊断结果对故障进行处理。测试结果显示该技术能够在1s内准确诊断测试对象各类故障。

连铸旋流沉淀池的设计优化

重力旋流沉淀池是连铸直接冷却循环系统的重要组成部分。河钢集团唐钢公司二炼钢新建连铸机水系统设计过程中,因场地有限,需要根据场地对下旋式重力旋流沉淀池进行优化设计。介绍了重力式旋流沉淀池的分类和工作原理,以唐钢二炼钢连铸旋流沉淀池设计为例,重点阐述了依据氧化铁皮的沉降速率-时间曲线,在高水力负荷、SS高去除率条件下,对旋流池各区域尺寸设计的优化。通过采取可调的旋流水力能量、优化加药点、双液位监控、水位与机组变频连锁、高耐磨过流部件智能自吸泵组、强化抓斗行进路线防护等技术措施,实现了渣沟无沉渣、无溅水,系统出水悬浮物长期稳定在SS≤50 mg/L,油脂≤10 mg/L,水泵机组等设备长期稳定运行。

连铸二冷区喷嘴布置方式优化方法

对现有连铸二冷区喷嘴布置进行分析,根据布置优化原则提出采用喷嘴水流密度数值叠加的方法,在拉坯方向和铸坯横断面方向上对喷嘴布置方式进行优化。其中,在铸坯横断面方向上,考虑了横向水流密度分布的不均匀性对铸坯凝固过程的影响,建立二维铸坯传热数学模型,仿真得到不同位置的铸坯断面凝固形貌,并比较了优化前后铸坯温度分布、凝固情况和铸坯质量。结果表明喷嘴布置方式优化后,二冷区铸坯在拉坯方向和断面方向上喷淋水区域内均匀冷却,周期性温度回升变小,表面温度能够均匀下降,保证了较好的铸坯内部质量。

气水雾化喷嘴最佳气水比的确定

从连铸喷雾冷却强度的控制因素入手,建立了冷却强度与水流密度、冲击速度、雾滴尺寸间的关系式。通过测定气水比对上述参数的影响,进而利用该关系式来计算冷却强度。结果表明,气水喷雾冷却过程存在最佳气水比值,但最佳气水比不是固定不变的,它随着水压的增加而减小。最佳气水比的确定对降低连铸二冷能耗具有重要的意义。

ROKOP高效方坯连铸二冷动态控制算法模型

针对连铸过程中拉速等因素变化,铸坯二次冷却实行静态控制而引起表面温度过大波动的问题,发展了一种针对ROKOP高效方坯连铸的二冷喷水动态控制算法及其相应的二冷动态控制模型。通过在计算机上的仿真实验及对静态和动态结果的对比表明,该种算法对连铸过程中拉速的变化具有良好的适应能力,拉速引起的表面温度波动很小。

污水回用于循环冷却水系统腐蚀影响因素的研究

作者利用动态、静态等多种试验手段 ,对城市生活污水回用于循环冷却水系统中有机物、浊度、Cl-、SO2 -4 、含盐量等因素对腐蚀的影响进行了深入的研究 ,为城市生活污水回用于循环冷却水的水质控制标准提供了试验依据。

方坯连铸二次冷却配水新模型

在连铸二次冷却喷淋区二冷各段,冷却水量只与拉速的变化相关联的二冷水模型的基础上,通过研究提出了二次冷却区各喷淋段的冷却水量Qi与钢液过热度(ΔT)、拉速(v)、浇注钢种化学成分、二冷水温相关系的二次冷却新配水模型,即Qi=K(a+bv+cv2)+d(ΔT-E)+F。研究了模型中各系数的确定方法。应用已开发的方坯连铸二冷仿真软件和通过研究确立的济钢二冷新模型进行了模拟计算。模拟结果以及新模型的生产实践表明,采用新模型确定的二冷各喷淋段水量进行冷却,铸坯冷却均匀,铸坯质量得到改善。

方坯连铸二次冷却数值仿真商用软件

基于二维方坯连铸凝固传热数学模型,使用VB语言设计开发了方坯连铸计算机数值仿真商用软件,从而为连铸生产提供了一个有效的计算机"实验平台"。运用该软件仿真,可对铸机结构和连铸工艺参数进行设计与优化。通过对多台铸机的实例运算及生产应用表明,文中所开发的方坯连铸二次冷却数值仿真商用软件具有较好的准确性、实用性、通用性和易操作性,其仿真结果已成功应用于国内多台铸机高效化改造的设计和生产。

铸造工艺参数对超高强铝合金低频电磁半连续铸锭微观组织的影响

采用低频电磁铸造技术(电磁场频率为25Hz,安匝数12800AT),按照不同的铸造工艺参数半连续铸造制备了直径为0.1m的超高强度Al12%Zn2.5%Mg2.5%Cu0.15%Zr合金锭坯,考察了铸造温度、铸造速度和冷却水强度对铸锭组织的影响。结果表明,铸造温度为710℃,铸造速度为100mm/min,冷却水强度为0.05m3/min时的低频半连续铸锭组织均匀细小,呈现近球形,边部和中间部位的晶粒大小差别较小,其平均晶粒尺寸分别为28μm和29μm。

连铸和热轧含油浊环水处理研究

连铸、热轧浊环水回水中含有高浓度悬浮物、油污等,容易引起喷淋系统喷嘴堵塞、过滤器滤料板结和偏流,使冷却水供水不足或供水不均,造成铸坯、轧件出现缺陷,以至次品。在已有处理设施不变的情况下,通过配合使用化学助剂,使浊环水供水水质得到很好的改善,解决了系统存在喷嘴堵塞和过滤器滤料板结的问题,满足了生产高质量铸件和精轧产品的需要。

板坯连铸二冷喷嘴性能测试及应用

对某板坯连铸二冷喷嘴冷态性能进行测试,得到喷嘴的流量特性、水流密度和冲击压力分布曲线及喷射角.采用数值叠加方法得到两个喷嘴按一定间距布置时的整体水流密度分布情况,分析表明,气水喷嘴布置间距为400 mm左右时,在断面方向可以保持铸坯均匀冷却.比较新旧喷嘴性能,新水喷嘴在使用5个月后特性总体变化不大,可以继续使用一段时间;新气水喷嘴使用8个月后喷嘴特性已改变,不能适应冷却需要,应及时检修或更换.

汽车用钢大方坯连铸二冷配水数学模型

应用开发的连铸传热数学模型对石家庄钢铁有限责任公司炼钢厂电炉车间所生产的5个钢种及2种规格铸坯的二次冷却配水进行了模拟计算;根据铸坯凝固冷却过程冶金准则的要求,经反复模拟及优化,得出了二次冷却区各段水量与拉速的二次关系式;综合考虑了过热度对铸坯凝固过程的影响,建立了新的二次冷却水控制模型,并应用于实际生产。

铸铁水平连铸用圆结晶器水冷套换热计算方法的研究

建立了铸铁水平连铸用圆结晶器水冷套的换热模型 ,给出了换热边界条件的确定方法。采用该计算方法可以计算不同水道结构参数和不同水流参数下水冷套的换热效果 ,其计算结果与实测结果基本符合。该计算方法可为设计结晶器水冷套时使用 ,并可与已有铸铁水平连铸铸坯凝固过程数值模拟计算程序结合 ,使之更加完善。

高浊度工业循环冷却水中菌藻的控制

由于旁滤失效,循环冷却水系统的浊度居高不下,细菌和腐蚀均难以控制达标,在短期内无法更换旁滤的情况下,对原水处理方案进行了调整。用新的氧化型杀菌剂取代次氯酸钠、有机胍杀菌剂代替原异噻唑啉酮类非氧化性杀菌剂,并加强了对运行的管理。经过半年的连续运行和监测,循环水各项指标均达到国家标准,有效解决了现场高浊度工况下的菌藻和腐蚀问题。