7200kW电机失步保护及带载自动再整步浅议

湘钢１４０００Ｎｍ＾３／ｈ制氧机组的７２００ｋＷ同步电动机采用了ＳＢＺ失步,带载自动再整保护技术。本文分析了该电动机实际运行中失步保护及带载自动再整步存在的问题及处理措施,并提出了今后的改进意见。     

湘钢7200KW同步电动机失步保护及带载自动再整步综合分析

１概述目前,在大、中型同步电机上广泛采用了ＳＢＺ技术其配套的ＤＳＢ型和ＬＢＳ型保护装置,作为断电失步保护和带励,失励失步保护。由于同步电机的失步事故,绝大部分都是由“非电机本身故障”所引起。因此,采用带载自动再整步,实现自动再整步,既可保障设备安全性,又保持运行连续性。１９９４年我厂７２００ｋＷ同步电动机采用了ＳＢＺ技术。在１９９４年和１９９５年两年多的运行中,先后因１０ｋＶ供电系统短路故障和上级变电站（三中央变电站）故障、电压消失等原因造成了６次同步电动机带励失步和断电失步,其中三次失步保护动…     

全生物法生产L-苹果酸的研究进展

综述了国内外利用微生物法生产L-苹果酸的发酵和提取工艺研究,并展望了全生物法生产L-苹果酸的应用前景.     

一步结晶法制取高纯度氰化亚金钾

选择恰当的条件，可以一步结晶制取含量大于６８．３％的高纯度氰化亚金钾。介绍了工艺过程、注意事项、含金量与杂质的分析方法及实际产品的分析结果。     

一步熔融还原炼铁流程的Yong分析

本文对一步熔融还原炼铁流利了Ｙｏｎｇ分析，考察了流程的能量分布情况，为一步熔融还原铁流程的节能和可行性研究提供了依据。     

PLC在铝型材氧化着色生产线上的应用

本文介绍了日本进口铝型材氧化着色生产线中,ＰＬＣ对行车实现全自动控制的系统构成和编程特点     

关于大型同步电机失步停机的故障分析

分析了一起同步电动机失步故障,并结合几种失步情况,对此次故障进行系统排查,确定导致电机励磁调节失控、电机失去动态稳定而失步的原因,提出整改方案和预防措施,并在此基础上做了相应的改进.     

结晶氯化铝两步焙烧制备氧化铝的研究

粉煤灰盐酸法生产氧化铝工艺中的结晶氯化铝经焙烧后转化为氧化铝产品,焙烧方式对氧化铝的理化性质有较大的影响。研究了不同焙烧温度下结晶氯化铝的物相转化,并进行了低温、高温两步焙烧及烟气吸收试验。结果表明,两步焙烧产生的氧化铝内部为多层片状结构,疏松多孔,晶型为γ-Al2O3,未生成α-Al2O3,产品粒度大于一步焙烧产出的氧化铝,有利于氧化铝电解;烟气中氯化氢回收率95.79%,吸收效率较高。     

高炉TRT静叶电液伺服同步系统改造

针对梅钢四号高炉TRT静叶电液伺服油缸不同步的问题,2018年炼铁厂对伺服油缸同步系统进行了技术改造。文章对电液伺服系统不同步的原因进行分析,提出了同步系统的改造技术方案,解决了由于静叶不同步造成机组频繁停机问题。     

一步法熔融还原炼铁流程的模拟

本文对一步熔融还原炼铁流程进行了流程系统计算机模拟研究，建立了相应的通用程度软件，对不同煤种、铁矿石组成、铁浴炉渣碱度、铁浴出口温度及二次燃烧率等参数条件下的各项物料消耗、能量消耗及利用等指标作出了预报，并与二步熔融还原炼铁流程进行了物耗、能耗、成本等的比较，其结果可为该炼铁流程的概念设计提供依据和参考。     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

45号钢钢水洁净度的控制研究

南钢45号钢的主要问题是铸坯和轧材裂纹率高,轧材易在热墩或热墩后的机加工过程中出现不同程度的开裂。究其原因是由于钢中大量的氧化物和硫化物夹杂使得其塑性、韧性及疲劳强度降低、加工性能变坏所致。因此,通过控制转炉终点碳质量分数和出钢过程温度、增加软吹氩时间、在LF炉中提前造白渣以及加强保护浇注等措施,降低了45号钢钢中夹杂物的数量,有效的避免了加工开裂。     

Independent integration of the 300 t BOF of Zhanjiang in heritage of steelmaking technologies of Baosteel

Through summary and extraction of current steelmaking design,process and equipment technologies and production technologies for 300 t grade converters in Baosteel,the article analyzes and elaborates the significance of independent integration of 300 t grade converters in Zhanjiang,major targets of the independent integration in converter process technologies,equipment packages and controls,the innovated critical technologies and comparison with overseas advanced technologies,major technical difficulties in the integration in Baosteel and their solutions,as well as general mindset and final objectives of the project.The total integration of technology for Shanghai No.1 Steel Making Plant of Baosteel was undertaken by Nippon Steel.And Kawasaki Steel was responsible for the total integration of technology for 4# and 5# converters of Shanghai No.2 Steelmaking Plant of Baosteel.Based on digestion,absorption and innovation of the introduced technologies,Baosteel has firstly achieved the independent integration of 6# converter,5# RH and 3# LF projects in the Shanghai No.2 Steelmaking Plant of Baosteel.Therefore, Baosteel shall take advantages of the favorable conditions and experiences and advanced steel making technologies of Baosteeel to master the imported new steelmaking technologies in the world and then form the advanced complete set steel making technologies and equipment at home and abroad.The achievement of independent integration of Zhanjiang Steel Making Project will make the breakthrough for the construction of large - sized steel making plant in Baosteel.300 t converter technology integration is undertaken by Baosteel independently in instead of by the foreign side in the past.     

The accuracy of parental recall of aspects of child development and of child rearing practices.

Retrospective accounts of child rearing obtained from parents of 3-year-olds were compared with reports they previously gave in the course of a longitudinal study begun with the birth of the child. The parents were quite inaccurate in their memory of details about child rearing practices and early development progress, in spite of the frequent rehearsal of these data due to their participation in the longitudinal study, and in spite of the relatively young age of the children. In-accuracies were greatest for items dealing with the age of weaning and toilet training, the occurrence of thumbsucking, and demand feeding. Inaccuracies tended to be in the direction of the recommendations of experts in child rearing, especially on the part of the mothers. In general, mothers recalled more correctly than fathers. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Train Characteristics on the Rate of Deterioration of Track Roughness

Track roughness describes in part the up and down waves in the longitudinal geometry of a railway track. A train passing over rough track experiences a degree of bouncing that generates oscillations in the forces exerted by the train’s wheels on the top of the rail, which in turn cause this roughness to worsen. The rate at which the track roughness deteriorates depends on the response of the track to the weight of the train and to the dynamic oscillations in wheel/rail forces, which in turn are affected by the properties of the train vehicles’ components and the speed of the train. The paper develops relationships between the severity of track roughness and the dynamic wheel/rail forces generated by a moving train using field data, and between those forces and the specific vehicle characteristics of speed, total mass, unsprung mass, suspension stiffness, and damping, using NUCARS simulations. These two relationships in turn are combined to show how the speed of the train and the design of the train vehicle’s bogie suspension can worsen or improve the rate of deterioration of track roughness. The relationships also provide a firm basis for the owner of track to set more representative charges levied on the train operator for using the track.     

对我国二十种土壤中稀土元素形态分组的研究

本文提出了土壤中稀土元素形态分组的方法,对我国20种土壤中稀土元素形态分组特征进行了评价。结果表明,土壤中稀土元素主要以残渣态存在,其次为氧化铁结合态和松结有机态。在碱性土壤中碳酸盐结合态仅次于氧化铁结合态,中酸性土壤中紧结有机态仅次于松结有机态,而碱性土壤中紧结有机态极低。土壤中交换态和氧化锰结合态稀土元素均比较低。     

Initiation of Motion of Calcareous Sand

This paper examines the initiation of motion of four natural and five sieved calcareous sand samples in unidirectional flow. Flume experiments yield the sediment transport rate as a function of bed shear stress up to bed-form development. Reference-based criteria are supplemented by visual observations to determine the critical shear stress. The results are compared with published data for rounded and irregular particles in terms of the median sieve size and the corresponding nominal and equivalent diameters as functions of particle Reynolds number. The comparison shows that the critical shear stresses of the irregular particles are higher than the Shields curve in the hydraulically smooth flow regime and lower in the rough turbulent flow regime.     

Assessment of Performance of Seismic Isolation System of Bolu Viaduct

The Bolu viaduct is a 2.3-km-long seismically isolated structure that was nearly complete when it was struck by the 1999 Duzce earthquake in Turkey. It suffered complete failure of the seismic isolation system and narrowly avoided total collapse due to excessive superstructure movement. This paper presents an evaluation of the design of the viaduct’s seismic isolation system and an assessment of its performance in the Duzce earthquake. Evaluation of the seismic isolation system’s design has revealed that it did not meet the requirements of the AASHTO Guide Specifications for Seismic Isolation Design. Analysis of the viaduct with motions scaled in accordance with the AASHTO Guide Specifications resulted in a displacement demand of 820 mm, which is far more than the 210 mm displacement capacity of the existing isolation system. Analysis of the viaduct for a simulated near-fault motion with characteristics consistent with the site conditions resulted in an isolation system displacement demand of 1,400 mm. This indicates that, even if the isolation system had been designed in compliance with the AASHTO, it would have still suffered damage in the earthquake.     

关于黄金地质勘探技术装备水平的思考

通过分析国内外地质勘探技术装备水平的现状,针对我国黄金行业地质勘探技术装备水平相对落后而制约了黄金工业发展的局面,提出了提高黄金地质勘探技术装备现代化水平应具备的有利条件。