冲击式水轮发电机转轮的铸造工艺设计

结合钢的流动特点和凝固特性,综合考虑充型过程及补缩效果,通过局部锆砂实现铸件的顺序凝固,设计旋转对开式芯盒成形形状比较复杂的水斗砂芯,利用三维建模软件及有限元分析对转轮进行了结构分析及优化,利用计算机模拟软件对铸件工艺参数进行了设计和优化。针对模拟后铸件可能出现的缺陷,提出了相应的改进措施。优化了浇注系统,合理设计冷铁和冒口,并确定了合理的铸造工艺参数范围,实现了转轮砂型铸造的成形方法。     

Inconel690在联氨溶液中的磨损行为(英文)

在控制法向载荷分别为20、50和80 N,位移幅值分别为80、150和200μm的两种不同环境下,以Si3N4陶瓷球/Inconel690平面接触的方式,在PLINT高温微动试验机上进行微动腐蚀试验,循环次数为2×104。结果表明:在滑移区,当载荷、位移幅值一定时,相同温度联氨溶液中的稳态摩擦因数比其在蒸馏水中高;稳态摩擦因数随溶液的温度增加而增加;磨损体积随溶液温度增加而增加。Inconel 690在联氨溶液摩擦过程中,磨损程度除受到位移幅值、荷载影响以外,温度对磨损体积有显著影响。温度的增加即降低溶液的溶解氧又促进联胺与溶解氧的吸收反应,起到降低氧化腐蚀的作用。在蒸馏水中Inconel 690合金材料的磨损机制主要为磨粒磨损和剥层,而在联氨溶液中其磨损机制主要为裂纹伴随磨粒磨损和剥层。     

Constructal design for a steam generator based on entransy dissipation extremum principle

Steam generator is optimized by applying entransy dissipation extremum principle and constructal theory and adopting analyti-cal method.The obtained results show that the optimal spacing between adjacent tubes,the mass flow rate of gas and the maximum entransy dissipation rate all depend on the dimensionless diameter of one tube,the dimensionless pressure difference number and the dimensionless length of flow channel of gas.Besides the three dimensionless groups,the optimal numbers of riser tubes and downco...     

Nano Structured Metal Oxides as Potential Sorbents for 188W/188Re Generator: A Comparative Study

Nanostructured oxides of Ti, Zr, and Al were synthesized to evaluate their efficacy as sorbent matrices for the preparation of ¹⁸⁸W/¹⁸⁸Re generator. These oxides, in many respects, can improve the efficiency of the generator by providing better selectivity and enhanced capacity for ¹⁸⁸W, which arises from a higher surface area, surface energy, and surface charge, compared to the attributes of conventionally used bulk alumina. The performance of these materials, in the context of preparation of ¹⁸⁸W/¹⁸⁸Re generators, were compared with respect to sorption capacity for ¹⁸⁸W, shelf-life of the generator, purity, and quality of ¹⁸⁸Re for radiopharmaceutical applications.     

Studies on the Development of a Two Stage SLM System for the Separation of Carrier‐free 90Y using KSM‐17 and CMPO as Carriers

Abstract

Solvent extraction studies of Y³⁺ and Sr²⁺ with 2‐ethylhexyl 2‐ethylhexyl phosphonic acid (KSM‐17) and octyl(phenyl)‐N,N‐diisobutylcarbamoylmethylphosphine oxide (CMPO) are carried out from aqueous media containing a wide range of nitric acid and other potential reagents to arrive at the operating conditions for the selective transport of ⁹⁰Y using supported liquid membrane (SLM) containing these reagents as carriers. Since the transport data of ⁹⁰Y using single cell SLM with KSM‐17 was available from our earlier experiments, single cell transport studies with CMPO carrier are only carried out to optimize the strippant phase. Transport studies with pure ⁹⁰Y is carried out using a transport cell with two SLMs one with KSM‐17 and the other CMPO carriers to optimize the transport parameters. Based on these data the development of a two stage SLM system for the generation of carrier free ⁹⁰Y from ⁹⁰Sr source is described. The procedure described is amenable for automation and scale up.     

Residual operators of uninorms

 Uninorms are an important generalization of t-norms and t-conorms, having a neutral element lying anywhere in the unit interval. A uninorm shows a typical block structure and is built from a t-norm, a t-conorm and a mean operator. Two important classes of uninorms are characterized, corresponding to the use of the minimum operator (the class U _min) and maximum operator (the class U _max) as mean operator. The characterization of representable uninorms, i.e. uninorms with an additive generator, and of left-continuous and right-continuous idempotent uninorms is recalled. Two residual operators are associated with a uninorm and it is characterized when they yield an implicator and coimplicator. The block structure of the residual implicator of members of the class U _min and of the residual coimplicator of members of the class U _max is investigated. Explicit expressions for the residual implicator and residual coimplicator of representable uninorms and of certain left-continuous or right-continuous idempotent uninorms are given. Additional properties such as contrapositivity are discussed.     

SS1H-70F型海洋钻机柴油发电机组控制系统研究

介绍了SS1H-70F型海洋钻机柴油发电机组控制系统的设计过程，提出了设计选型的原则，并对发电系统母线设计和保护进行了计算，应用自行研究的DYT-3型电压调节器成功地解决了2种不同规格、不同容量、不同转速、不同电子调速器的发电机组并网问题，并网运行指标好，为钻机电传动系统的改造提供了技术经济可行新思路。     

Influence of quadrature‐axis reactance of large turbine generator on operation

Two‐pole large generators are extensively used in power utilities. Growing demand for electric power in recent years has led to substantial increases in the capacity of generators. In line with this trend, our company has manufactured two‐pole turbine generators in the 900,000‐kVA to 1,200,000‐kVA classes. As the capacity of generators becomes larger, equivalent circuits are increasingly expected to improve their precision in estimating operation characteristics. The Park model has been widely used as an equivalent circuit model. The Park model with quadrature axis transient reactance $x_{q}^{\prime}$ is claimed to be useful for accurately estimating the load rejection characteristics of turbine generators. However, it is difficult to measure $x_{q}^{\prime}$, few studies based on measured data have appeared. As one of the few examples, we have conducted a measured data on a 500,000‐kVA‐class generator. Recently, the authors obtained test data on $x_{q}^{\prime}$ of a 900,000‐kVA‐class generator. In this study, based on these data, we studied the effect of $x_{q}^{\prime}$ using the finite element method and a transient analysis program (EMTP‐ATP). © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(3): 17–27, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21099     

机端(静态)励磁方式在发电厂中应用

本文通过对某热电厂全厂停电事故的描述和原因及改进措施的分析,探讨了发电机组机端静态励磁和无刷励磁的特点和应用场合,通过实例阐述了励磁方式的选择对电力系统稳定性的重要性。