共查询到18条相似文献,搜索用时 125 毫秒
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通过水模试验对邯郸钢铁集团有限责任公司邯宝炼钢厂连铸结晶器液面波动原因进行分析。结果表明,随着板坯连铸机拉速提高、吹氩量增加、铸坯断面的增加,结晶器钢液面波动量增大;随着浸入式水口浸入深度增加和水口出口角度增大,结晶器内钢液面波动量减小。选择合适的拉速、恒速浇铸、优化浸入式水口形式和浸入深度、保持适当的吹氩量、执行标准化操作,可以降低结晶器钢液面波动量,提高连铸坯质量。采取优化措施后,结晶器钢液面波动量逐渐恢复到±3 mm以内,热轧卷板边部翘皮和夹杂缺陷比例逐月降低,缺陷率从2010年11月0.41%控制到2011年4月以后0.1%以下。 相似文献
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建立了1∶0.6的结晶器水模型和结晶器原型数学模型,采用高速摄像机及分析软件研究了连铸工艺参数对结晶器水模型内气泡分布行为的影响;采用离散相模型和VOF模型的数学模拟方法,研究了连铸工艺参数对结晶器内气泡分布和钢渣界面波动行为的影响。结果表明,通过数学模拟获得的结晶器内气泡分布和水模型试验结果吻合性较好;增加吹氩量,结晶器内氩气泡尺寸增大,分布更均匀;吹氩可以降低结晶器窄面附近区域钢液的波高,但会导致水口附近波动加剧;增大拉速时,结晶器内氩气泡尺寸减小,分布更均匀,结晶器窄面波高增大,水口附近液面波高显著降低;增大水口倾角和浸入深度,有助于抑制水口附近和窄面附近的波动,气泡在结晶器内的分布相对较为均匀,气泡尺寸变化不显著。拉速为1.2 m/min、水口倾角为15°、水口浸入深度为160 mm,较优的吹氩量为4 L/min。研究结果可以为优化工艺参数、防止钢液卷渣、提高铸坯质量提供理论依据。 相似文献
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针对宝钢一炼钢厂的结晶器吹氩水口进行了1:1水模实验,研究了不同板坯宽度、拉速、水口出水口面积、出水口角度、浸入深度和吹气量等条件下结晶器液面波动和流股在窄面的冲击点的冲击点的变化情况,并提供了水口优化设计及操作参数,为提高连铸生产率及铸坯质量提供了依据。 相似文献
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结晶器保护渣卷入到钢液中后容易被生长的凝固坯壳捕获,最终在冷轧板上形成由卷渣引起的表面缺陷,会严重恶化钢产品的质量。结晶器液面卷渣现象受到钢液成分、温度、流动方式和吹氩流量的影响。结晶器表面钢液流速大小是反映钢渣界面是否发生卷渣的重要参数,但在实际浇铸过程中,不能在线预测不同拉速、吹氩流量和水口浸入深度下结晶器表面钢液的最大速度。提出一种基于板坯连铸结晶器内多相流动数值模拟的结晶器卷渣在线预测方法。首先,建立结晶器内三维多相流动数学模型,模拟不同拉速、吹氩流量和水口浸入深度下的钢液流动行为;其次,对计算得到的表面钢液流速的最大值进行拟合,得到固定浇铸断面下结晶器表面最大流速的预测公式;最后,通过某钢厂的插钉板工业试验验证了所提方法的准确性。研究发现,不同浇铸参数下表面钢液流速沿结晶器宽度方向呈现先增加再减小的变化趋势,在结晶器宽度1/4位置具有最大值。钢液流速在较小和较大拉速下分别在窄面和水口附近具有较大值;在较小和较大吹氩流量下分别在水口和窄面附近具有较大值;随着水口浸入深度增加,钢液流速在水口和窄面附近变化较小。基于拟合的钢液流速公式,通过比较最大钢液流速与钢渣界面发生卷渣的临界流速,实现了结晶器卷渣的在线预报。 相似文献
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以国内某钢厂220 mm×1800 mm板坯连铸结晶器为原型,根据相似性原理建立相似比为0.6的水模型,利用粒子图像测速技术(PIV)对比不同浸入式水口(SEN)的出口角度、浸入深度及水口底部结构条件下的结晶器内流场流速特征,同时使用波高仪对液面波动振幅进行实时监测,并结合F数分析各SEN条件对结晶器内钢液流动特征.研究发现,在各浸入式水口条件下,位于结晶器液面1/4宽面处附近出现矢量流速向下的剪切流,同时在水口附近发现不规则漩涡.试验结果表明:浸入式水口的出口角度、浸入深度的增加能够强化上回旋区缓冲作用,降低结晶器液面表面流速;尽管凹底结构SEN能减弱钢液湍动能,但其对1/4宽面处剪切流速度的影响不大.另外,液面波动幅度和F数变化规律一致,且当浸入式水口出口角度15°、20°,浸入深度135 mm、145 mm条件下波幅与F数最为合理,从而减小或避免液面卷渣,提高连铸坯质量. 相似文献
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高拉速厚板坯连铸结晶器流场影响因素的模拟研究 总被引:1,自引:1,他引:0
运用数值模拟研究方法,研究高拉速厚板坯连铸结晶器流场的影响因素;研究浸入式水口结构、水口控流方式、水口出口角度、水口浸入深度、结晶器宽度、结晶器厚度、吹氩等因素对结晶器流场、液面流速以及初生坯壳的影响.结果表明在高拉速下,结晶器的流场不稳定因素增多,工艺参数对结晶器流场的影响因数增加.在高拉速下结晶器流场流速高,液面波动大,液钢流束冲击深度大,势必造成产品质量的下降趋势,因此高拉速厚板坯连铸过程必须采用电磁制动或流场控制技术,降低高流速带来的不利影响;水口结构与结晶器规格最优化与匹配能得到适宜的结晶器流场;同时发现高拉速钢液流束对结晶器初生坯壳的影响严重,是高拉速漏钢率高的直接原因之一. 相似文献
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Baokuan Li Toshimitsu Okane Takateru Umeda 《Metallurgical and Materials Transactions B》2001,32(6):1053-1066
Biased flow occurs frequently in the slab continuous casting process and leads to downgraded steel quality. A mathematical
model has been developed to analyze the three-dimensional biased flow phenomena associated with the effects of static magnetic-field
application and argon gas injection in the slab continuous casting process. By moving the submerged entry nozzle (SEN) from
center to off-center, the biased flow and vortexing flow in the mold can be reproduced in the numerical simulation. The existence
of a vortexing flow is shown to result from three-dimensional biased flow in the mold. A vortex is located at the low-velocity
side adjacent to the SEN. The vortex strength depends on the local horizontal velocity of molten steel and decreases gradually
with distance from the free surface. The vortexing-zone size depends on the biased distance of the SEN, and the intensity
of the vortexing flow depends on the casting speed of the continuous caster. Only when the location and strength of the magnetic
field are properly chosen, can the vortexing flow be suppressed by a static magnetic-field application. The effect of argon
gas injection on the vortexing flow is not remarkable. The combination of magnetic-field application and argon gas injection
can correct the biased flow and suppress the vortexing flow by suppressing the surface velocity and removing the downward
velocity near the SEN in the mold. 相似文献
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LIFENG ZHANG SUBO YANG KAIKE CAI JIYING LI XIAOGUANG WAN BRIAN G. THOMAS 《Metallurgical and Materials Transactions B》2007,38(1):63-83
Fluid flow in the mold region of the continuous slab caster at Panzhihua Steel is investigated with 0.6-scale water model
experiments, industrial measurements, and numerical simulations. In the water model, multiphase fluid flow in the submerged
entry nozzle (SEN) and the mold with gas injection is investigated. Top surface level fluctuations, pressure at the jet impingement
point, and the flow pattern in the mold are measured with changing submergence depth, SEN geometry, mold width, water flow
rate, and argon gas flow rate. In the industrial investigation, the top surface shape and slag thickness are measured, and
steel cleanliness including inclusions and the total oxygen (TO) content are quantified and analyzed, comparing the old and
new nozzle designs. Three kinds of fluid flow pattern are observed in the SEN: “bubbly flow,” “annular flow,” and an intermediate
critical flow structure. The annular flow structure induces detrimental asymmetrical flow and worse level fluctuations in
the mold. The SEN flow structure depends on the liquid flow rate, the gas flow rate, and the liquid height in the tundish.
The gas flow rate should be decreased at low casting speed in order to maintain stable bubbly flow, which produces desirable
symmetrical flow. Two main flow patterns are observed in the mold: single roll and double roll. The single-roll flow pattern
is generated by large gas injection, small SEN submergence depth, and low casting speed. To maintain a stable double-roll
flow pattern, which is often optimal, the argon should be kept safely below a critical level. The chosen optimal nozzle had
45-mm inner bore diameter, downward 15 deg port angle, 2.27 port-to-bore area ratio, and a recessed bottom. The pointed-bottom
SEN generates smaller level fluctuations at the meniscus, larger impingement pressure, deeper impingement, and more inclusion
entrapment in the strand than the recess-bottom SEN. Mass balances of inclusions in the steel slag from slag and slab measurements
show that around 20 pct of the alumina inclusions are removed from the steel into the mold slag. However, entrainment of the
mold slag itself is a critical problem. Inclusions in the steel slabs increase twofold during ladle changes and tenfold during
the start and end of a sequence. All of the findings in the current study are important for controlling slag entrainment. 相似文献
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Interfacial Fluctuation Behavior of Steel/Slag in Medium-Thin Slab Continuous Casting Mold With Argon Gas Injection 总被引:1,自引:0,他引:1
The flow field of molten steel and the interfacial behaviour between molten steel and liquid slag layer in medium-thin slab continuous casting mold with argon gas injection was studied by numerical simulation, in which the effects of nozzle submergence depth and port angle, casting speed, and argon gas flow rate on the flow and the level fluctuation of molten steel were considered. The results show that the molten steel jet from the submerged entry nozzle (SEN) with three ports into the mold and form three re-circulation zones including one upper re-circulation zone and two lower re-circulation zones. Argon gas injection results in a secondary vortex flow in the upper zone near the nozzle. For a given casting speed and argon gas flow rate, increasing the side port angle and submergence depth of nozzle can effectively restrain the steel/slag interfacial fluctuation. Increasing the casting speed would prick up the level fluctuation. For a fixed casting speed, argon gas flow rate has a critical value, the interfacial fluctuation with argon gas injection are stronger than the case without argon gas injection when the argon gas flow rate is less than the critical value, but when the argon gas flow rate exceeds the critical value, the level fluctuation is calmer than that without argon gas injection. 相似文献
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A three-dimensional mathematical model for describing the electromagnetic field and flow field of molten steel in high casting speed slab continuous casting mold with electromagnetic level stabilizer (EMLS) system was developed, in which the effects of current intensity and frequency on the electromagnetic field and flow field were considered. Simulation results indicate that the electromagnetic force (EMF) along the mold width direction presents the centre-symmetric double-peak parabola distribution. The EMLS system leads to the flow velocity of molten steel decreases, especially near the free surface. Both the EMF increases with the current intensity and frequency (in the range of optimum frequency value), so the flow velocity of molten steel in the mold decreases obviously. As the current intensity increases from 800 A to 1000 A, the maximum free surface velocity decreases from 0.515 m/s without magnetic field to 0.155 m/s and 0.12 m/s, respectively. While the current frequency increases from 2 Hz to 6 Hz, the maximum surface velocity decreases from 0.177 m/s to 0.101m/s. The molten steel flow in mold is influenced obviously by the current intensity and frequency. 相似文献