宽板坯结晶器浸入式水口结构优化的数值模拟

以某钢厂宽板坯连铸结晶器为研究对象,利用商业软件PHOENICS建立一个三维有限差分模型,模拟宽板坯连铸结晶器内钢液的流动分布.通过分析水口底型、倾角、插入深度等工艺参数对钢液面波动、流股对结晶器窄面的冲击力及涡心高度的影响,得出适用于宽规格结晶器的合理的浸入式水口.通过研究,为优化宽板坯结晶器内钢液的流场及浸入式水口的设计提供了科学依据.     

方坯连铸结晶器浸入式水口结构类型的研究

应用流场计算软件PHOENICS及水力模型,模拟了方坯连铸结晶器内钢液的流场和流动分布。在此基础上模拟计算了几种不同形式的水口对流动形态的影响,并用水力模型试验进行了验证。通过数值模拟,为优化结晶器内钢液的流场以及浸入式水口的设计提供了科学依据。     

连铸

连铸中间包温度的控制；Q235方坯内裂原因分析；电磁搅拌在小方坯连铸机的生产实践；棒材生产用连铸压缩比的影响因素；连铸板坯内部缺陷及结晶器内钢液电磁流动的控制。     

连铸坯凝固过程中传输现象基础知识系列讲座

连铸结晶器中钢液的流动方式对去除钢水中的夹杂物，防止卷渣和铸流冲刷凝固层十分重要，介绍了板坯连铸结晶器中的钢液流动和水口出口倾角，水口浸入深度及浇铸速度等参数对流动行为的影响，同时概括了小方坯弧形结晶器中钢液流动特点。     

连铸坯凝固过程中传输现象基础知识系列讲座 第十四讲 连铸结晶器中的钢液流动

连铸结晶器中钢液的流动方式对去除钢水中的夹杂物、防止卷渣和铸流冲刷凝固层十分重要。介绍了板坯连铸结晶器中的钢液流动和水口出口倾角、水口浸入深度及浇铸速度等参数对流动行为的影响，同时概括了小方坯弧形结晶器中钢液流动特点。     

FTSC薄板坯连铸结晶器流场数值模拟

利用商业软件GAMBIT和FLUENT，针对FTSC薄板坯连铸结晶器，建立三维有限体积模型，用来描述结晶器内钢液流动特征。在此基础上，分析了浸入深度、拉坯速度以及水口倾角等参数对结晶器流场的影响，为FTSC薄板坯连铸结晶器相适应的浸入式水口结构尺寸优化提供参考。     

漏斗型结晶器内钢液的流动及传热研究

摘自冶金部钢铁研究总院研究生王来华的博士学位论文,导师:邵象华 本文结合国家“七·五”重点科技攻关课题——薄板坯连铸,对漏斗型结晶器内钢液流动规律进行了物理模拟和数值计算,并对钢液的温度分布进行了理论分析。采用延时照相和激光测速的方法系统地对漏斗型结晶器内的流动状态进行了实验研究,发现漏斗型结晶器内的流动可以分为三个区域:水口出口的射流区,水口上部的旋滚区和水口下部的旋滚区。三个区域的大小受水口形状、水口插入深度、水     

连铸采用结晶器电磁搅拌法获新成果

在连铸机的结晶器内旋转搅拌钢液,称为结晶器电磁搅拌(MAGNETOGYR)法。采用此法对连铸产品具有多种作用。本文强调的是结晶器搅拌对轧材带来的好处,并列举有关例子。用铝镇静钢140毫米连铸方坯轧成(?)25～40毫米的圆钢。这种钢材经过专门检验,选定深度为钢材直径1%及2%的钢材缺     

薄板坯连铸漏斗形结晶器内卷渣行为物理模拟

针对高拉速下薄板坯连铸结晶器内的液面卷渣问题，建立了1∶1水力学模型，采用水/真空泵油模拟钢/保护渣介质，研究了连铸拉速、水口插入深度、保护渣黏度对漏斗形结晶器内液渣层变化及卷渣行为的影响。结果表明，随着拉速提高，结晶器内液面波高升高，液面高度自窄边向水口方向逐渐降低，液渣层厚度相应由薄变厚，导致结晶器窄边附近钢液裸露；结晶器内窄边至水口之间1/2处波高变化较大、液面流速最大、易发生剪切卷渣。在试验条件下，采用增加水口插入深度、降低最高拉速、适当提高保护渣黏度等方法，使液面速度小于0.486 m/s的临界流速、液面波动指数F数小于5.45,可防止结晶器内产生剪切卷渣。然而，这些手段不能避免结晶器内水口附近的旋涡卷渣，这是因为薄板坯连铸钢通量大以及漏斗形结晶器和鸭嘴形水口容易形成负压旋涡造成的。     

采用超导磁体控制连铸结晶器内钢液流动

为了改善连铸坯质量，用静磁场和移动磁场控制连铸结晶器内钢液流动的技术已经实用化。在比现在更高生产率（即连铸拉坯速度）的连铸中，需要增大磁场强度（以便有效控制钢液流动方向和速度）。因此，有人建议在结晶器上附加超导磁性（超导磁铁）可以获得强磁场；并且，通过水银模型实验确认此举可以大幅度降低结晶器内液体弯月面的表面流速和下降流速度。下面概要介绍在试验型连铸机上用超导磁体进行的控制结晶器内钢液流动试验。实验方法在垂直弯曲型板坯连铸机上的结晶器外侧，设置了可以附加上下两段静磁场的超导磁体，所产生的最大磁场…     

冷凝炉衬传热机理和计算模型

简要阐述了冷凝炉衬的概念及传热机理,利用一维传热模型,对已有数据进行分析,对比冷凝炉衬和传统保温炉衬对电炉能耗的影响,认为冷凝炉衬是一个整体系统;同时介绍了渣壳厚度检测方法及简单的渣壳厚度计算模型,对保护炉壳及指导日常生产有一定的意义。     

三环减速器在冶金领域应用探讨

三环减速器为重庆钢铁设计研究院开发的一种新型传动装置,它突破了传统减速器构思原理,结合了传统的动轴传动减速器与定轴传动减速器的优点,是一种新型高效的传动装置.该项目1995年被联合国世界知识产权组织与中国专利局联合授予"中国专利金奖",国家科委将其列为"国家科技成果重点推广计划"项目.目前该设备已在冶金、水利、建筑等重型传动机构上逐步采用,处于广泛推广的应用时期.     

变结构智能调节器的研制

介绍了一种变结构智能调节器的设计方法。它适用于加热炉这类大惯性、非线性、受外界因素干扰的对象．利用模式识别实现智能切换．增加系统的抗干扰能力．提高系统的快速性．通过试验表明．控制效果明显改善．     

Isolation and partial characterization of (PAF) platelet-activating-factor

Platelet-activating-factor is a new mediator of anaphylaxis released in numerous mammalian species from basophils and mastocytes by antigens, anti-IgE antiserum, ionophore A 23187, C3a, C5a and neutrophil cationic protein. It is probably a lyso-1-phosphatidylcholine, as evidenced by structural studies isomg phospholipases. It may explain the involvement of platelets in immunopathology.     

交流变频调速装置控制皮带张力

详细介绍一种新型皮带输送机张力自动控制装置的原理。该装置采用PLC控制和变频调速电机驱动，有友好的人机界面，全自动控制，具有控制精度高、功能完善、运行可靠、维护简单等优点。     

浅谈硅铁和工业硅精炼用合成渣

分析了硅铁和金属硅炉外精炼用合成渣的特性及组成,指出合成渣各种组成成分的物理化学性质,分析了各成分在各渣系的反应特性,最后,通过实践比较得出较为理想的合成渣配比。     

Permeability of the small intestine after intra-arterial injection of histamine-type mediators and irradiation

Permeability and selectivity of rabbit small intestine were estimated by a perfusion technique after intra-arterial injection of histamine-type mediators and intestinal irradiation. It was shown that the histamine-type mediators caused an increase in capillary permeability which produced an overall moderate increase in transmucosal permeability with a moderate loss of selectivity. Local intestinal irradiation caused a very marked increase in permeability and a profound loss of selectivity. It was felt that this was produced partly by an increase in capillary permeability but largely by damage to the epithelial basement membrane. It is concluded that the intestinal capillary endothelium is both rate-limiting and selective, though not to a major degree in either case. The epithelial basement membrane, however, appears to be both rate-limiting and markedly selective.     

Note: purification and characterization of the bacteriocin PsVP-10 produced by Pseudomonas sp

A bacteriocin (bacteriocin PsVP-10) produced by Pseudomonas sp. R-10 was purified by a simple method that included an extraction of the bacteriocin with chloroform, followed by cation exchange chromatography. The purity of the bacteriocin was verified by RP-HPLC. It is a peptide of 2.4 kDa, very stable to heat, to proteolytic enzymes and to pH. It presents a very broad spectrum of antimicrobial activity against Gram-positive and Gram-negative bacteria.     

350MW西门子汽轮机快速启动中热应力控制特点

宝钢电厂4号发电机组使用的是西门子350 MW SST5-5000型凝汽式汽轮机。该汽轮机运用组级程序自动控制、人为断点辅助判断的方式,实现了各初参数下从盘车到并网全过程的快速自动化启动,在自动化程度和启动效率方面达到了国内领先水平。着重对西门子汽轮机的X准则和汽轮机热应力估算器进行分析,总结出西门子汽轮机自动化启动中热应力控制特点及其具体的实现方法,可为国内发电企业汽轮机实现自动化启动提供参考。     

Detection of alcohol misusing patients in accident and emergency departments: the Paddington alcohol test (PAT)

The list of hepatitis viruses is increasing over the years. Now the viruses range from A to G. Hepatitis A virus is a short incubation RNA virus which is transmitted oro-faecally. It does not cause chronic illness but may be fatal in a few cases especially in pregnancy. It can now be prevented by vaccination. Hepatitis B virus is a long incubation DNA virus which is transmitted mainly through blood and blood products. It causes chronic illness and can lead to liver cancer in some cases. It can be prevented by vaccination and WHO is now recommending global vaccination of all infants irrespective of endemicity of hepatitis B virus. Hepatitis C virus is an RNA virus which used to be known as parenterally transmitted non A non-B virus. It leads to chronic illness and can lead to liver cancer. It is now responsible for most cases of post transfusion hepatitis in Europe, North America and Asia. Hepatitis Delta virus is a defective virus which requires hepatitis B virus for its existence. Thus it affects only those who have hepatitis B virus. Hepatitis E virus used to be known as the enterically transmitted non-A non-B virus. It is transmitted oro-faecally and seems not to lead to chronic illness. It is endemic in some areas like Middle East and parts of Africa. Hepatitis G virus is just being described. More information about it will soon be available.