水电站水轮机调速器的调试与维护

水轮机调速器是负责调节水轮机组转速的重要设备.水电站运行期间,要定期对水轮机组调速器进行调试与维护,使其各项功能维持正常状态,以确保水轮机组的转速正常.本文简单介绍了水轮机调速器及功能,分析了水轮机调速器的调试与维护操作.旨在为水轮机调速器的规范操作提供参考.     

东风4型机车柴油机调速器油封漏油的原因分析与改进

1 问题的提出 目前,我段配属的东风4B型机车使用的是C型联合调节器,为电源驱动的无级调速操纵装置.该型调速器在使用过程中经常发生调速器漏油现象.调速器漏油使调速器内的油位低于正常线,严重时会造成无油,使调速器内部部件损坏而无法工作;或者产生调速器游车、回手柄停机、起机困难等故障现象,使机车发生机破、临修等事故.以我段的机车举例如下. (1)1998年3月5日,东风4型1051号机车在库内F4次修,起机交验合格后,在库外停留4小时后乘务员接班起机时发现,由于调速器油封老化脱落,调速器内已无法存油,使柴油机无法起机工作,造成一起零公里临修.     

广州蓄能水电厂自适应微机调速器控制算法研究

针对抽水蓄能机组调速器控制工况繁多、控制逻辑较常规水火电机组复杂的问题,以广州蓄能水电厂# 4蓄能机组调速器为倒,介绍了发电与抽水工况下蓄能机组调速器的控制逻辑、相关算法及监控系统与调速器配合完成机组的有功控制过程,可供其他抽水蓄能电厂控制调速器参考.     

柴油机飞车的原因及排除

柴油机的飞车是指柴油机转速失去控制,转速越来越高的故障.飞车会造成柴油机杵缸、断轴等重大事故.柴油机一般是在刚启动或工作中负荷突然消失或减轻的时候才会出现飞车故障,而在负荷下工作,不会发生飞车故障.发生飞车的原因有: 1.调速器壳内润滑油加得过多,影响了调速作用;调速器摩擦离合器打滑;调速器高速限制螺钉和安全档松动;飞快脱出或卡滞;调速弹簧拆断、推力轴承或调速器轴承损坏,使调速器失灵,造成飞车.     

西霞院水电站微机调速器自动减增出力原因及改进

介绍了西霞院水电站DFWST-100-6.4-STARS型微机调速器运行中一起自动减增出力的异常过程,分析了调速器自动减增出力的异常与原程序配置缺陷有关,因而修改了调速器原程序,新编的调速器程序投入运行后,水轮发电机组运行稳定、正常.     

青铜峡水电站9号机调速器的改造

针对青铜峡水电站9号机调速器的技术改造,叙述了WBST- 100-40型水轮机调速器的配置、功能和工作原理以及安装调试,为宁夏青铜峡水电站在今后的调速器改造工作提供参考.     

调速器故障诊断

针对调速器故障征兆和原因的复杂性,根据水电站调速器故障事实,结合专家的实际经验构建调速系统故障诊断知识库,建立故障诊断专家系统.实例表明,该系统推理准确性高,满足调速器故障诊断的实用性要求.     

机械调速器改装为电子调速器的应用研究

分析了135系列柴油机喷油泵机械调速器改装电子调速器的原因,介绍了其组成、工作原理、安装、调试,注意事项以及效果比较.     

迅速排除电子调速器故障一例

排除电子调速器的故障,应把已有机械调速器的知识和排除故障的技能,理性的转化到分析和排除电子调速器的故障中,它将是迅速排除其故障的关键所在.     

福建电网水电厂一次调频试验剖析

针对当代电力系统中水轮机调速器已成为水轮机控制系统的控制核心,依据福建电网大量水电站一次调频试验结果,论述了水轮机调速器与电网负荷频率控制间的关系,分析了调速器在电网一次调频中的作用、静态与动态特性,提出了福建电网水电机组并网工况下调速器PID参数整定范围及机组功率控制模式.     

自然通风技术研究方法及工具

目前自然通风主要有三种研究方法:简单的理论分析法、实验法和数值模拟法。本文概括介绍了后两种方法的研究现状,并对它们进行了分析比较,提出各种方法的适用场合。在数值模拟法中还介绍了几种可用于分析自然通风系统的通风特性和热特性的常用工具软件,对各自工作原理和应用特点进行了比较,并对使用方法和应用场合提出了建议。     

Potential method in the theory of thermoviscoelastic mixtures

In this article, the linear theory of binary thermoviscoelastic mixtures is considered and the basic boundary value problems (BVPs) of steady vibrations are investigated. Namely, the fundamental solution of the system of equations of steady vibrations is constructed explicitly and its basic properties are established. Green’s second and third identities are obtained and the uniqueness theorems for classical solutions of the internal and external basic BVPs of steady vibrations are proved. The surface and volume potentials are constructed and their basic properties are given. The determinants of symbolic matrices are calculated explicitly. The BVPs are reduced to the always solvable singular integral equations for which Fredholm’s theorems are valid. Finally, the existence theorems for classical solutions of the internal and external BVPs of steady vibrations are proved by the potential method and the theory of singular integral equations.     

Study of contact melting inside isothermally heated vertical cylindrical capsules

Close-contact melting processes of phase change material (PCM) inside vertical cylindrical capsule are studied. PCM are heated by the capsule isothermally at the bottom and side. The theoretical formulas of the melting rate and thickness of liquid layer during the heat transfer process are obtained by analysis, which are convenient for engineering predictions. Finally, the factors that affect melting are discussed, and conclusions are drawn.     

US nuclear energy policy Provision of funds for decommissioning

The five recognized methods of decommissioning nuclear power plants are reviewed, and are linked with US nuclear regulatory policy. Although over 60 US nuclear reactors have been decommissioned since 1960, none have been large-scale commercial facilities. Costs of the decommissioning alternatives are estimated, but are acknowledged to be highly tentative and uncertain. Five methods of providing funds for decommissioning and the actual practices of US electric utilities are analysed in terms of the policy issues they present. Revenue bonding and sinking fund approaches are argued to be the soundest means to recover decomissioning uncertainties surrounding decommissioning are considered.     

质子交换膜燃料电池系统控制与应用现状

描述了质子交换膜燃料电池(PEMFC)系统的控制及其在中低功率领域中的应用现状。首先概述了过程模型和电压预测模型，对影响电堆性能的各参数进行分析。其次，从目前运用的简单控制方法、混合动力驱动、效率优化、故障容许等方面对PEMFC系统的分析与控制结构作了说明。然后介绍了PEMFC的几种具体应用。最后结合国内外的相关研究进展，提出了一些有待进一步研究的方向。     

无心感应熔铜、铝炉用耐火材料

介绍了熔炼铜、铝及其各自合金的无心感应炉用新型干式成型耐火材料的研制、性能和使用情况。该材料成本低,成型工艺简便,使用寿命长。     

开放空气环境中的池火灾及其危险性分析

本文涉及开放空气环境中池火灾及其危险性分析，对池火灾的如下物理特征进行了总结；（１）火焰的几何形状及尺寸；（２）火焰表面的热辐射通量；（３）热辐射的传播，文中并归纳了热辐射的各种破坏准则，推导了进行池火灾危险性分析的程序和算法，通过数值模拟计算，讨论了一些重要规律。     

Stochastic approach for daily solar radiation modeling

Mathematical modeling of solar radiation continues to be an important issue in renewable energy applications. In general, existing models are mostly empirical and data dependent. In this paper, a novel approach for solar radiation modeling is proposed and illustrated. The proposed application consists of hidden Markov processes, which are widely used in various signal processing topics including speech modeling with successful results. In the experimental work, mean of hourly measured ambient temperature values are considered as observations of the model, whereas mean of hourly solar radiation values are considered as the hidden events, which constitute the outcomes of the proposed mathematical model. Both solar radiations and temperatures are converted to quantized number of states. Finally, after a training stage that forms the transition probability values of the described states, the hidden Markov model parameters are obtained and tested. The tests are repeated for various numbers of states and observations are presented. Plausible modeling results with distinct properties in terms of accuracy are achieved.     

A review on ports’ readiness to facilitate international hydrogen trade

The existing literature on the hydrogen supply chains has knowledge gaps. Most studies focus on hydrogen production, storage, transport, and utilisation but neglect ports which are nexuses in the supply chains. To fill the gap, this paper focuses on ports' readiness for the upcoming hydrogen international trade. Potential hydrogen exporting and importing ports are screened. Ports' readiness for hydrogen export and import are reviewed from perspectives of infrastructure, risk management, public acceptance, regulations and standards, and education and training. The main findings are: (1) liquid hydrogen, ammonia, methanol, and LOHCs are suitable forms for hydrogen international trade; (2) twenty ports are identified that could be first movers; among them, twelve are exporting ports, and eight are importing ports; (3) ports’ readiness for hydrogen international trade is still in its infancy, and the infrastructure construction or renovation, risk management measures, establishment of regulations and standards, education and training all require further efforts.     

Heat transfer performance of a double-loop separate-type heat pipe: Measurement results

An experimental study is presented for the heat transfer performance of a rectangular double-loop natural circulation system, in which the condensers are made of double tubes with water-steam as the working fluid. Detailed temperature measurements of the core fluid and the wall are made, from which overall heat transfer coefficients for the evaporator, condensers, and entire system are obtained. Parametric studies of the liquid charge level, fluid properties, and heating or cooling conditions on the heat transfer performance are presented and correlation equations are given. The results show that the overall heat transfer coefficients for the evaporator, condensers, and entire loop are all increasing with decreasing liquid charge level. Overhead phenomena at low liquid charge level and thermal oscillation at some situations are also observed and discussed.