干式机械泵真空系统在40t VD炉的应用实践

传统VD炉真空系统使用庞大的蒸汽喷射泵系统,喷射泵使用的蒸汽由蒸汽锅炉产生并发出。蒸汽喷射泵存在能量效率低、使用成本高等缺点。宝钢特钢有限公司40 t炼钢产线精炼工序VD炉采用干式机械泵真空系统替代原有蒸汽喷射真空系统。VD炉干式机械泵真空系统热负荷试车成功以来,已经历3 000余炉钢的生产验证,除尘与气体冷却系统、干式机械泵真空系统运行正常,能够满足VD工艺的要求;干式机械泵真空系统相比蒸汽泵真空系统,在满足真空处理的生产要求下,节能降本优势明显。     

马钢钢水真空净化处理VD炉热试成功

近日 ,马鞍山钢铁集团 2 0 0 2年 11月开工兴建的钢水炉后真空处理 VD炉 ,在其三钢厂已系统全自动抽真空运行处理钢水一次热试成功。经过程测定 ,钢中氧含量由进 VD站前的 98.5× 10 - 6 已降至出 VD炉后的 37× 10 - 6 ,所有的真空处理指标都达到设计的理想值。马钢钢水真空净化处理VD炉热试成功@陈钢     

机械泵真空系统应用于VD炉的工艺实践

主要介绍了机械泵在莱钢120 t VD炉的应用实践,重点阐述了机械真空泵的运行情况和冶金效果。生产实践表明,使用机械真空泵系统的VD炉,其冶金效果达到或优于使用多级蒸气喷射泵真空系统的VD炉,脱[H]率达63.5%,能源介质消耗成本较多级蒸气喷射泵真空系统低3.5元/t钢。机械真空泵以电能为介质,生产组织灵活。     

干式VD炉与蒸汽VD炉工艺与能耗的对比分析

文章阐述了炼钢精炼炉工艺流程,介绍了包钢干式VD炉和蒸汽VD炉的技术工艺参数和特点,对炼钢厂蒸汽VD炉和干式VD炉两个脱真空系统的耗能设备进行实时监测,通过对测试技术数据的分析计算得出了吨钢耗能比、节能率、吨钢费用比等经济技术指标。     

基于干式机械泵的SW718H脱氢工艺技术研究

为给SW718H钢真空脱氢处理提供一定依据,对在干式机械泵真空脱气炉(VD炉)中生产SW718H钢的真空脱氢工艺技术进行了研究.叙述了真空脱氢的动力学控制因素,对VD炉的SW718H钢真空脱氢生产实践进行分析,发现干式机械泵VD炉真空脱氢主要集中在钢液近表面反应区域(渣眼).总结了在干式机械泵VD炉处理中真空度66.7 Pa以下和近表面反应面积控制在0.277 m2以上时,某一终点氢含量的氩气量和脱氢时间的理论计算公式,可为生产提供指导依据.结果表明,采用干式机械泵VD炉精确控制脱氢时间、真空度可以使SW718H钢真空脱气后的氢含量达到1.0×10-4％以下.     

VD炉脱氢率的影响因素及工艺优化

为了充分发挥VD炉的脱氢作用,提高生产效率,以VD炉脱氢热力学和动力学为基础,对影响脱氢率的因素进行对比分析。结果表明:钢水原始氢含量、真空度、高真空保持时间、氩气流量等是影响VD炉脱氢效果的主要因素。通过现场真空脱气工艺参数优化,VD炉的脱氢率得到提高,为生产低氢高质量品种钢创造了条件。     

石钢60t VD炉脱氧工艺实践

介绍了石钢60t VD炉的主要参数、脱氧工艺,分析了氩气流量、真空脱氧时间、弱搅拌处理对VD炉脱氧的影响.     

60吨VD真空装置喷射泵的研究与改造

对60吨VD真空装置喷射泵的改造，对于保证VD炉的正常生产有一定的普及意义。     

首钢京唐VD炉工艺设计特点

介绍了首钢京唐钢轧部真空精炼炉的选择依据及VD炉工艺设计特点。双工位VD炉主要由真空泵及真空度自动调节系统、车载式移动真空罐车及罐盖系统、合金加料系统、底吹氩系统等组成,具备脱气、脱氧、自然脱碳及调整合金成分、去除夹杂和净化钢水的冶金功能。双盖双罐位布置模式,可缩短精炼处理时间约5～10 min,使转炉 精炼 连铸衔接匹配合理、顺畅;在线喂线工艺的实施,可提高芯线吸收率,实现环境友好。     

120t VD真空炉脱氢生产实践

基于氢对钢材质量的影响及脱氢机理,分析真空脱氢的影响因素,总结承钢120 t VD炉在试生产期间进行的真空脱氢生产实践。实践表明,通过控制氢的来源和在VD炉脱氢过程中控制溶渣、真空度、氩气流量和压力,VD脱氢后氢含量(质量分数)被控制在1.2×10~(-6)以下。     

VD真空精炼温度预报模型

开发了较为完善的VD终点温度在线预报系统。采用MINITAB软件确定影响VD过程温降的主要因素为抽真空时间、保压时间、吹氩时间、非真空时间、VD搬入钢水的过热度、LF处理时间以及转炉出钢至VD初始测温之间的钢包运输时间。应用神经网络方法对VD处理终点的钢水温度进行在线预报,系统在线连续预报了95罐,预报温度与实际测量温...     

钢液VD真空处理脱氮数学模型

根据钢液VD真空处理过程氮溶解热力学和脱氮动力学理论,建立了高碳钢VD真空处理过程脱氮的数学模型。采用该模型结合VD处理过程的工艺条件,可实现钢液VD真空处理过程脱氮预测。     

Greater synergism of retinoic acid receptor (RAR) agonists with vitamin D3 than that of retinoid X receptor (RXR) agonists with regard to growth inhibition and differentiation induction in monoblastic leukemia cells

Retinoids and 1alpha,25-dihydroxyvitamin D3 (VD3) cooperatively induce the differentiation of myeloid leukemia cells. We investigated the role of retinoid receptors (RARs and RXRs) in the combined effects of retinoids and VD3 on growth inhibition and differentiation induction in human monoblastic leukemia U937 cells by using RAR- or RXR-selective retinoids. An isobologram analysis showed that both combinations were synergistic with regard to inhibiting the proliferation, and RAR agonists exhibited greater synergism with VD3 than did RXR agonists. RXR agonists alone induced nitroblue tetrazolium (NBT) reduction and expression of CD11b in U937 cells, whereas RAR agonists alone did not. On the other hand, RAR agonists and RXR agonists enhanced the differentiation induced by VD3, but RXR agonists required higher concentrations. An RAR antagonist inhibited the differentiation induced by RAR agonists plus VD3, but not that induced by RXR agonists plus VD3. Thus, RARs and RXRs act differently in their synergism with VD3. RAR agonists are more potent than RXR agonists with regard to synergism with VD3, and their combination may be useful in differentiation therapy against myeloid leukemia.     

The t(5;17) variant of acute promyelocytic leukemia expresses a nucleophosmin-retinoic acid receptor fusion

The classical action of the hormone 1,25-dihydroxyvitamin D3 (VD) is the regulation of calcium metabolism. In contrast, the peptide hormone atrial natriuretic factor (ANF) is one of the few known nonclassical VD responding genes. We screened the promoter of the rat ANF gene and identified a typical VD receptor (VDR) binding site formed by a direct repeat of two hexameric core binding motifs spaced by three nucleotides, between positions -907 and -891. Like most of the DR3-type VD response elements this sequence is bound with high affinity (Kd = 0.53 nM) by a heterodimer formed by VDR and retinoid X receptor. In a heterologous promoter context one copy of this sequence mediated an about fourfold gene activation by VD and a half-maximal activation (EC50) value of 0.48 nM VD. This characterizes the identified sequence as one of the most potent VD response elements.     

The association of shame and guilt with suicidality

1,25-dihydroxyvitamin D3 (VD) is a modulator of growth and differentiation of many cell types, including keratinocytes. We have recently shown in cultured keratinocytes that VD induces tyrosine phosphorylation of proteins involved in signal transduction, such as Shc. In an attempt to identify VD-responsive tyrosine kinases, we studied the effects of VD on the activity of the nonreceptor tyrosine kinase Src. Although VD did not stimulate Src activity in keratinocytes cultured in standard media containing 0.15 mM calcium, preincubation of the cells with 1.8 mM Ca2+ caused a rapid activation of Src in response to VD (10(-8)-10(-7) M). Elevation of calcium concentration alone caused an increase in Src activity as well, but the peak of Src activity was delayed (60 min vs. 15 min) and approximately 2-fold lower in comparison with VD-treated cells. VD treatment also induced tyrosine dephosphorylation of Src and a formation of an Src-Shc-Grb2 complex. Taken together, these findings imply that Src is involved in VD signaling in keratinocytes.     

VD真空精炼技术与装备的发展现状

介绍了VD真空精炼技术的发展现状,指出VD功能多元化应是今后发展的主要趋势,提出重点研究开发氧脱碳（碳脱氧）、深脱硫、深脱气技术是实现VD功能多元化的关键。在此基础上,介绍了高效化生产装备和干式机械泵系统应用于VD真空精炼的情况,指出干式机械泵系统应用于真空精炼是一种可行的选择。     

Verbal-discrimination learning following a free-recall familiarization training procedure.

Investigated the effects of transfer from a modified free-recall task to verbal-discrimination (VD) learning. The free-recall procedure was designed to impact increments in experimental frequency to specific words that appeared in VD. 4 experimental groups, with 30 undergraduates in each, were given prior free-recall exposure to either all right VD items (A-R), all wrong (A-W), both the right and wrong items from same VD pairs (B-S), or both the right and wrong items from different VD pairs (B-D). A 5th group of 30 Ss served as a control and learned a free-recall list which did not contain any VD items (C). In terms of number of correct responses during VD learning, the groups were ordered as follows: A-R, C, A-W, B-S, and B-D. Results are interpreted as being consistent with derivations from the frequency theory of VD learning. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibition of tumor growth and angiogenesis by vitamin D3 agents in murine renal cell carcinoma

PURPOSE: To investigate the effect of active vitamin D3(VD) agents on tumor growth and metastasis. MATERIALS AND METHODS: BALB/c mice were inoculated with murine renal cancer Renca and graded doses of 1,25-dehydrovitamin D3 or 1- hydrovitamin D3 were given intraperitoneally every other day beginning on day 1, 3, or 7 and ending on day 9, 11, or 15. Direct cytocidal activity and angiogenic activity were evaluated by 48-hour MTT assay and by the colorimetric method, respectively. RESULTS: Both VD agents inhibited tumor growth and prolonged the life span of Renca-bearing mice in a dose-dependent manner and both suppressed tumor growth in athymic mice and euthymic mice with eliminated NK activity. Marginal body-weight loss without appreciable hypercalcemia was observed in mice given VD agents. When treatment was delayed on day 7, the VD agents failed to inhibit tumor growth. The MTT assay showed no direct cytotoxicity of VD agents on Renca. Tumor angiogenesis was inhibited to 46 to 30% of the control level by VD agents. Furthermore, VD agents reduced pulmonary and hepatic foci in the metastatic models. CONCLUSIONS: These results suggest that VD agents may be effective as a treatment for renal cell carcinoma, especially when micrometastases are involved.     

顶底复吹转炉蒸汽在100 t VD精炼设备上的应用

转炉生产过程中产生大量的饱和蒸汽,但没有得到有效的利用;而VD精炼需要一定的微过热蒸汽。转炉蒸汽供应VD精炼的结果表明,2座100 t转炉的饱和蒸汽得到有效利用,转炉蓄热器饱和蒸汽完全满足VD使用要求,供给VD的蒸汽压力0.8～1.0 MPa,过热度10～15℃。钢水经VD 15 min精炼后,[H]≤1.5×10^-6,总[O]≤15×10^-6,脱氮率≥25%。文中介绍了转炉余热蒸汽在100 t VD精炼设备上的应用难点及解决方案。